Complete Motor Guide for Robotics
by:KISSTOY
2021-03-11
A robot is an electro-mechanical device that can react in some way to the environment and make autonomous decisions or actions to achieve specific tasks.
Robot developing human
To make a mechanical device that can be moved by itself, its motion must be modeled, planned, perceived, driven and controlled, and its motion behavior can be affected by \"programming.
This definition means that if the device contains a movable mechanism affected by sensing, planning, driving, and controlling components, it can only be called \"robot \".
The motor and the actuator are the devices that make the robot move.
The motor and the actuator convert electrical energy into physical motion.
The vast majority of actuators produce rotational or linear motion.
In this note, I will explain the more common types of motors and actuators, the fundamentals of them and how to control them.
You already know that an electric motor is used to \"drive\" something in a robot: its wheels, legs, tracks, arms, fingers, sensor turrets, cameras, or weapon systems.
There are dozens of types of electric Madas, but I will discuss the most common types of amateur robots.
The motor is classified as: AC (
AC current)
Motor is rarely used by mobile robots, because most robots are DC-powered (DC)
From the battery.
In addition, since the electronic components use DC, it is also more convenient to provide the same type of power supply for the actuator.
The AC motor is mainly used in industrial environments where very large torque is required, or in industrial environments where the motor is connected to a power/wall socket.
So I won\'t explain the AC motor here.
The motor controller is an electronic device that helps the micro-controller to control the motor.
The motor controller acts as an intermediate device between the micro-controller, power supply or battery and the motor.
Although the micro controller (
Brain of robot)
Determines the speed and direction of the motor, because its power is very limited, so they cannot be driven directly (
Current and voltage)output.
On the other hand, the motor controller can provide current at the required voltage, but cannot decide how the motor should operate.
Therefore, in order for the motor to move properly, the micro-controller and the motor controller must work together.
In general, the micro-controller can guide how the motor controller can power the motor through standard and simple communication methods (such as serial port or PWM.
In addition, some motor controllers can be manually controlled by analog voltage (
Usually created with potentiometer).
The physical size and weight of the motor controller may vary significantly, from the device used to control the mini Sumo robot less than the tip of the hand to the large controller weighing several kilograms.
The size of the motor controller is usually related to the maximum current it can provide.
A larger current means a larger size.
Since there are several types of motors, there are several types of motor controllers (
Different types of motors require different types of controllers)
: Brushed DC motor is a motor that uses two brushes to conduct current from the power supply to the stator.
There are several changes in the brush DC motor, but the permanent magnet DC motor (PMDC)
It is widely used in robot field.
Brushed DC motors are widely used from toys to push
Button adjustable car seat. Brushed DC (BDC)
The motor is cheap and easy to drive and is easy to buy in all sizes and shapes.
The brushed DC motor consists of six different components: the shaft, the stator/rotor, the diverter, the stator, the magnet and the brush.
The brushed DC motor consists of two magnets facing the same direction, which surround the two-ring wires located in the middle of the brushed DC motor and around the rotor.
The coil is placed on the surface of the magnet, causing the current to flow to the magnet.
This creates a magnetic field that eventually pushes the coils away from the magnet they face and causes the rotor to turn.
There are two terminals for Brushed DC motors;
When applying voltage on two terminals, the output proportional speed to the shaft of the brushed DC motor.
The brush DC motor consists of two parts: the stator of the housing, the permanent magnet and the brush and the rotor composed of the input shaft, the winding and the diverter.
The stator of the brush DC motor is stationary, while the rotor rotates relative to the brush DC motor stator.
The stator generates a static magnetic field around the rotor.
A rotor, also known as a rotor, consists of one or more windings.
When these windings are energized, they create a magnetic field.
The poles of this rotor magnetic field will be attracted by the opposite poles generated by the stator, resulting in the rotation of the rotor.
When the motor is turned, the winding is constantly energized in different order so that the Poles generated by the rotor do not exceed the Poles generated in the stator.
This switching of the magnetic field in the rotor winding is called phase change.
Different from other motor types (i. e.
DC, AC induction)
, The BDC motor does not need a controller to switch the current in the motor winding.
On the contrary, the phase change of the winding of the BDC motor is mechanically completed.
The segmented copper sleeve located on the shaft of the BDC motor is called a diverter.
When the motor is turned, the carbon brush slides over the diverter and is in contact with different parts of the diverter.
These segments are connected to different rotor windings, so when the voltage is applied to the brush of the motor, a dynamic magnetic field is generated inside the motor.
It is important to note that the brushes and switches are the most easily worn parts of the BDC motor because they slide each other.
Application: Advantages: limitations: in addition to the sound emitted by the electrical brush of the recharger, these motors produce a lot of electrical noise that goes back into other circuits and causes problems.
Access to the DC motor: What I am talking about is control of direction and speed.
By simply reversing the polarity of the battery connection, the direction of the DC motor can be reversed.
The speed of the motor can be controlled by changing the voltage level, and the DC voltage level can be changed through the PWM signal.
For higher voltage level speed will be higher and for lower voltage level speed will be lower.
In fact, drive circuits are used in applications that use some kind of controller and require speed control.
The purpose of the drive circuit is to give the controller a way to change the winding current of the BDC motor.
The driving circuit discussed in this section allows the controller pulse width modulation to supply the voltage to the BDC motor.
Compared with the traditional simulation control method, changing the speed of the BDC motor is a more effective method.
In some cases, the motor only needs to rotate in one direction, and then a single switch topology with PWM Modulation can be used to change the voltage applied to the motor to control its speed.
The higher the PWM duty cycle, the faster the motor will run.
The figure shows the circuit that drives the BDC motor in one direction using a single FET (
Field effect transistor).
Note that there is a diode on the motor in the circuit.
This diode is designed to prevent electricity on the back-netic Flux (BEMF)
Damage the voltage of the MOSFET.
BEMF is generated when the motor rotates.
When the MOSFET is turned off, the winding in the motor is still charging at this time and reverse current is generated.
The D1 must be properly rated to dissipate the current.
The resistors R1 and R2 in the figure are very important for the operation of the circuit.
R1 protects the microprocessor from current spikes, while R2 ensures that the transistor is off when the input pin is three-on.
When two directions of rotation are needed or need to be located (
Most robots are needed. afull H-
Use the bridge with PWM control. The H-Bridge is a 4-
A transistor circuit that allows you to reverse the current to the motor. With an H-
Bridge and PWM pins, you can control the speed and direction of the motor.
To understand, follow the next step.
The H-bridge is an electronic circuit that enables the voltage to be applied to the load in any direction.
These circuits are commonly used for robots and other applications to allow the DC motor to run forward and backward. An H-
The bridge is a transistor.
Based on the circuit that can drive the motor clockwise and anticlockwiseclockwise.
This is a very popular circuit-the driving force behind countless robots that must be able to move forward and backward.
Basically, an H.
The bridge is a combination of four transistors, two input lines and two outputs :(
Note: more often than not in a welldesigned H-
A bridge that includes an anti-excitation diode, a base resistor, and a Schmidt trigger. )
To understand this, H-
Both sides of the bridge should be broken, or halfbridges.
Half of the first and second quarters
The third and fourth quarters made up for the other half. bridge.
Half of these.
The bridge is able to switch one side of the BDC motor to either a power supply voltage or a potential to ground.
For example, when Q1 is on and Q2 is off, the left side of the motor will be at the potential of the supply voltage.
Turning Q4 on and off Q3 will ground the other side of the motor.
Switching elements (Q1. . Q4)are usually bi-
A transistor or FET transistor, at some height.
Voltage application igbt.
Pay attention to the diodes on each transistor (D1-D4).
When transistors are turned off, these Diodes Protect the transistors from current spikes generated by BEMF. The top-
The end of the bridge is connected to the power supply (
Battery, for example)and the bottom-The end is grounded.
Capacitors can be used in parallel with diodes.
But this is optional.
The values of these capacitors are generally within the range of 10pf.
The purpose of these capacitors is to reduce the RF radiation generated by the bending of the converter.
Basic operation mode of H-
The bridge is fairly simple: If Q1 and Q4 are turned on, the left lead of the motor will be connected to the power supply while the right lead will be connected to the ground.
The current begins to flow through the motor (let’s say)
The forward direction and the motor shaft begin to rotate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If Q2 and Q3 are turned on, the reverse will occur, the motor will be powered on in reverse, and the shaft will start to rotate backwards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
You should never close Q1 and Q2 on the bridge (or Q3 and Q4)
At the same time.
If you do, you just create a very low
Resistance path between power and GND, effectively shortening-
Your power circuit.
This situation is called \"shooting\"
This is a way to almost guarantee a quick destruction of your bridge or something else in the circuit.
H-there are many different models and brands
Bridging IC is available.
Most commonly used are Texas Instruments L293NE or Texas Instruments SN754410 and L298 from Italian semiconductor.
L293d L293NE/SN754410 is a very basic H-bridge.
It has two bridges, one on the left side of the chip and one on the right side, which can control two motors.
It can drive up to 1 amp of current and work between 4 amps. 5Vand 36V.
Small DC motors commonly used in robot robots can operate safely at low voltage
Bridge works very well. The H-
Bridge has the following pins and features: Keep in mind that all motors have different sizes.
Small motors are designed for applications with higher torque values.
Small high though-
Due to the use of rare earth magnets, efficient bearings and other features that increase costs, these connectors tend to be expensive.
Large motors can generate greater torque, but higher current is also required.
High-current motors require more large-capacity batteries and larger control circuits that do not overheat and burn out under load.
Therefore, match the size of the motor with the rest of the robot.
When the large size is not important, do not overload the small robot with a large motor.
When determining the size of the motor, compare the available torque after the gear slows down.
Gear deceleration always increases torque.
The increase in torque is proportional to the gear deceleration: If the deceleration is 3:1, the torque is increased by about three times (
But this is not the case due to friction loss). For H-
Please visit the bridge IC and Module: you already know that the DC motor cannot be connected directly to the arduino pin as it will burn your arduino.
So you have to connect the transistor between the arduino and the motor.
Let\'s first control a small DC motor using a single transistor.
All you know is that speed can be controlled.
PWM is used to control the speed of the DC motor.
Connection circuit as shown in figure-1.
The Arduino PWM pin must be connected to the base pin of the transistor.
Now, connect the motor with H-Bridge IC (
I\'m using L293 here). Follow Fig-3 & Fig-4.
We can now control the speed and direction.
Pin 9 is used as a PWM pin and a switch is added to control the speed.
L293 is a double H bridge IC.
So, you can control the two motors through a single IC.
Connect the two motors to the IC as shown in figure 5 and use the following code.
Make changes as per your requirements. .
The gear DC motor can be defined as an extension of the DC motor, which has previously been clarified for its insight details.
The gear assembly of the slow down DC motor is connected to the motor.
The speed of the motor is calculated according to the rotation of the shaft per minute, and calculated in RPM.
Gear assemblies help increase torque and reduce speed.
Using the correct gear combination in gear Madras, its speed can be reduced to any ideal number.
In this concept, the gear reduces the speed of the vehicle, but increases the torque, which is called Gear deceleration.
This insight will explore all the minor and major details that make the gear head and gear geared motor work.
The working DC motor of the DC deceleration motor works within a considerable voltage range.
The higher the input voltage, RPM (
Rotate per minute)of the motor.
For example, if the motor works at 6-
At 12 V, it will have a minimum RPM at 6 V and a maximum rpm at 12 V.
In terms of voltage, we can set the equation to: RPM = K1 * V where K1 = the induced voltage constant V = voltage applied.
It is very interesting to know the work of gears.
It can be explained by the principle of conservation of momentum.
The gear with a smaller radius is higher than the gear with a larger radius.
However, larger gears bring more torque to smaller gears and vice versa.
Comparison of input gear angular velocity (
The one that transmits energy)
The output gear gives the gear ratio.
When multiple gears are connected together, conservation of energy is also followed.
The direction of the rotation of the other gear is always opposite to the adjacent gear.
In any DC motor, the rotation speed and torque are inversely proportional.
Therefore, the gear with a large torque will provide a smaller rotation speed and speed.
In the gearedDC motor, the concept of pulse width modulation is applied.
For example, the unmounted DC motor can rotate at 12000 rpm and provide 0. 1 kg-cm of torque.
In order to reduce the speed and increase the torque proportionally, a 225:1 deceleration was added: 12000 rpm/225 = 53. 3 rpm and 0. 1 x225 = 22. 5 kg-cm.
Now the motor will be able to move more weight at a more reasonable speed.
In the gear DC motor, the gear connecting the motor and the gear head is very small, so it passes more speed to the larger tooth part of the gear head and makes it rotate.
The larger part of the gear further turns the smaller duplex part.
The small duplex section receives the speed of torquebut not from its predecessors it transfers to the largerpart of other gears and so on.
The duplex part of the third gear has more teeth than the other parts, so it will pass more torque to the gear connected to the shaft.
The control of the gear reduction motor can be exactly the same as that of the DC motor.
Application: Advantages: limitations: This is especially low
Plastic gear train used with low costvoltage motors.
Additional resistance can make these gears
Low speed train.
For controller and motor browsing: www. sparkfun.
DC (BLDC)
There are many kinds of motor names, such as: brushless permanent magnet motor, permanent magnet AC motor, permanent magnet synchronous motor, etc.
This confusion occurs because the DC motor cannot operate directly from the DC voltage source.
However, as we will see, the basic working principle is similar to the DC motor.
The BLDC has a rotor with a permanent magnet and a stator with winding.
It is essentially a DC motor that rotates from the inside out.
The brush and the diverter have been eliminated and the winding is connected to the control electronics.
Control the function of the electronic device to replace the converter and power up the appropriate winding.
As shown in the animation, the winding is powered on in a pattern that rotates around the stator.
The energized stator winding guides the rotor magnet and switches when the rotor is aligned with the stator.
No sparks, this is an advantage of the BLDC motor.
There are several restrictions on the brush of the DC motor;
Brush life, brush residual, maximum speed, electric noise.
The BLDC motor may be cleaner, faster, more efficient, less noisy and more reliable.
However, electronic control is required for the BLDC motor.
Then, the structure of the brushless DC motor is very similar to the AC motor, making it a real synchronous motor, but one drawback is that it is more expensive than the equivalent \"brushed\" motor design.
There are two types of brushless RC motor, brushless RC motor and brushless RC motor.
The permanent magnet of the Inrunner brushless motor is located inside the magnet.
The exterior of the Outrunner brushless motor has a permanent magnet.
The faster the motor speed, the higher the efficiency.
The Inrunner motor rotates very fast and is much more efficient than the outrunner motor.
The Inrunner brushless RC motor needs to install a deceleration gearbox between the motor and the propeller of the RC aircraft.
The disadvantage of Inrunner is the additional parts that can and do fail.
The gear is stripped and the shaft of the gearbox is easily bent.
This can also be an obstacle when you are neatly installing the gearbox motor combination of the RC aircraft, especially under the shield.
Operation theory the mechanical principle of brushless motor is very simple.
The only moving part is the rotor, which contains the magnet.
When things get complicated, the order of the excitation winding is arranged.
The polarity of each winding is controlled by the current direction.
The animation demonstrates the simple mode that the controller will follow.
The alternating current changes the polarity, giving each winding a \"push/pull\" effect.
The trick is to keep this mode in sync with the speed of the rotor. There are two (widely used)
This can be achieved.
Most hobby controllers measure the voltage generated (back EMI)on the un-
Power-on winding.
This method is very reliable when running at high speed.
As the speed of the motor decreases, the resulting voltage becomes more difficult to measure and more errors are generated.
Newer hobby controllers and many industrial controllers use Hall sensors to measure the position of the magnet directly.
This is the main way to control the computer fan.
The control of the brushless DC motor is very different from that of the ordinary brushed DC motor, because this type of motor contains some methods to detect the angle position of the rotor (
Or magnetic poles)
Used to generate feedback signals needed to control semiconductor switching devices.
Hall sensors are the most common position/electrode sensors, but there are also some motors that use optical sensors.
Using the hall sensor, the motor controls the polarity of the drive circuit to switch the magnet.
The motor can then be easily synchronized with the digital clock signal, thus providing precise speed control.
It can be constructed as a brushless DC motor with an external permanent magnet rotor and an internal magnet stator or an internal permanent magnet rotor and an external magnet stator. In figure 4 (A)
, The Green winding marked \"001\" is energized as the Arctic, and the blue winding marked \"010\" is energized as the Antarctic.
Due to this excitation, the Antarctic of the rotor is aligned with the Green winding, and the Arctic is aligned with the red winding marked \"100.
To move the rotor, the \"red\" and \"blue\" windings are energized in the direction shown in Figure 4 (B).
This caused the red winding to become the Arctic, and the blue winding to become the Antarctic.
Due to the development of rejection force, this change in the stator magnetic field produces torque (
North-red windingNorth alignment)
And attraction (
Blue winding northSouth alignment)
Make the rotor move clockwise.
In fact, the DC motor is a three-phase AC motor.
Speed is controlled using electronic speed control or ESC.
The Brushless ESC system basically creates a three
Phase AC power supply with limited voltage input and output from onboard DC power supply, run the brushless motor by sending a series of AC signals generated from the ESC circuit, using a very low rotational impedance.
According to its physical configuration, the brushless motor is called the Super run motor or the inrunners motor, which is very popular in the \"electric flight\" Radio
Compared with the traditional Brush Motor, its efficiency, power, life and weight are very small, so the pneumatic roller brush enthusiasts can be controlled.
However, the brushless AC motor controller is much more complex than the brushed motor controller.
The correct phase changes as the motor rotates, and ESC will take this into account: Normally, the back potential of the motor is used to detect this rotation, but changes in the use of magnetism are present (Hall Effect)
Or optical detectors. Computer-
There are usually users with programmable speed control-
Allow setting the specified option for low voltage cut-
Limit, timing, acceleration, braking and direction of rotation.
By switching any two of the three leads from ESC to the motor, the direction of the motor can also be reversed.
The current rating of the ESCAn ESC will have a power limit.
ESC needs to be larger, heavier, and more expensive to handle more power supplies.
It is important to know the peak current of your motor at full throttle.
This determines the current rating you should look for in ESC.
Always select ESC with a current rating higher than you need.
If the car is about to pull 12A, 25A-
Rated ESC is a better choice than 10Arated one.
Even if you only fly under a half throttle, 10A ESC can overheat and Cook.
The ESCs are relatively light and maintain a high resale value, so this is a project in your power system that is not worth wasting time.
Choosing the right type and identifying the minimum current rating are two steps.
The next choice depends on your preference.
All ESCs have voltage limits.
Some people even have more than one!
What is your battery voltage?
Select ESC designed to work at the same or higher voltage.
Some ESCs are designed for low voltage (below 13V)
Some for medium voltage (below 25V)
, Some for high voltage (above 25V).
You should not connect the high voltage battery to the low voltage ESC, but it is also a waste to use the high voltage ESC with the low voltage battery.
Compared with the \"brush\" motor, the advantages of the DC motor are higher efficiency, high reliability, low electrical noise, good speed control, and more importantly, there is no wear of the brush or the changer that produces a higher speed.
Their downside, however, is that they are more expensive and more complex to control.
Arduino controls the brushless motor designed for automatic and remote control aircraft and vehicles often require separate controllers.
They are typically sensor-free types and speed control using pulse signals of the standard servo type.
It is very simple to control the BLDC motor.
Most ESCs require a frequency of 50 hz I. e.
The cycle and speed of the A20 MS depend on the duty cycle you provide.
1 mswill reduce its speed to a minimum or even stop (
It depends on the ESCmodel)
The 2 ms pulse will run the motor at its maximum speed.
The value between them gives you a change in speed.
Usually ESCs need to be higher than the voltage provided by Arduino from his 5 v pin: Usually they need 2 LiPo cells (around 8V).
In order to achieve this, all circuits must be powered by an external power supply directly connected to ESC instead of via Arduino, which will be powered by ESC\'s BEC circuit.
To do this, it is enough to connect the red and black of the control connector to the 5 v and GDN of the Arduino board.
The rest of the circuit is very easy: the voltage reading of the potentiometer comes in from the Arduino\'s pin 9 to ESC\'s signal, and then to pin 0.
Sometimes ESC needs to be calibrated, and in the case of ESCs, calibration means setting the maximum and minimum speed of the motor based on the maximum and minimum width of the PWM signal sent by Arduino.
The PWM signal read by ESC is the same type as the servo signal, which means that the servo Library from Adruino can be used to calibrate and control the ESCs.
ESC sets the speed of the motor according to the ratio of the high flow signal.
Calibration includes programming ESC to understand the pwm wave corresponding to the motor stop and maximum speed.
The default signal range for most servo motors and ESCs is the high signal width between 1000 and 2000 microseconds in a repeat period of 20 milliseconds (
Assuming a PWM signal of 50 hz).
For the four helicopters, however, we would like the range to be as wide as possible in order to have greater incremental control over the motor.
To do this, we calibrated the ESCs to read the signal width at a stop speed of 700 and a maximum speed of 700 from 2000 to 2000 microseconds.
Some ESC cannot read signals below 700 microseconds.
Calibration of ESCs is very simple.
To enter the programming mode, the maximum servo signal (
2000 microseconds)
Send to ESC, ESC power up and wait for two seconds, then send the minimum servo signal (
700 microseconds).
Once a series of confirmed beeps are issued by ESC (
Send a special waveform signal to the motor to make a beep sound)
, ESC calibration (
See ESC specific data tables for details).
It just needs to read \"throttle\" from 0-1023 to 0-179 (
Analog reading of servo \"degree)
Then send to ESC through the servo Library.
Even if it\'s very simple, this sketch is very useful when you want to calibrate a new ESC to use the Arduino\'s servo Library.
Application: Advantages: limitations: individual controllers are required for certain types of brushless motors to operate.
For a brushless DC motor, a visual servo motor is an electrical device that can push or rotate objects very precisely.
If you want to rotate and object at a specific angle or distance, then you can use a servo motor.
It is just made up of simple motors running through a servo mechanism.
If a DC-driven motor is used, then it is called a DC servo motor, and if it is an AC-driven motor, then it is called an AC servo motor.
We can get a very high torque servo motor in a small and light package.
According to these features, they are used in many applications such as toy cars, remote control helicopters and aircraft, robots, machines, etc.
The position of the servo motor is determined by the pulse, and its circuit is placed next to the motor.
Today\'s servo system has huge industrial applications.
The application of servo motors is also very common in remote control toy cars, used to control the direction of movement, and also very often used in the motor of moving CD or DVD player tray.
In addition, we can see hundreds of other servo motor applications in our daily life.
The main reason for using the servo system is that it provides angle accuracy. e.
It will only spin as we want and then stop and wait for the next signal to take further action.
This is different from the normal motor, which starts to rotate when it is applied to it, and the rotation continues until we turn off the power.
We cannot control the progress of the motor;
But we can only control the speed of the rotation and turn it on and off.
The servo mechanism consists of three parts: it is a closed loop system that uses a positive feedback system to control the movement and final position of the shaft.
Here, by comparing the output signal and the reference input signal, the device is controlled by the feedback signal.
The reference input signal is compared with the reference output signal here, and the third signal is generated by the feedback system.
The third signal is used as the input signal of the control device.
As long as there is a difference between the feedback signal or the reference input signal and the reference output signal, this signal exists.
Therefore, the main task of the servo system is to keep the output of the system at the expected value in the presence of noise.
Working Principle of Servo Motor (DC or AC)
, Potentiometer, gear assembly and control circuit.
First, we use the gear assembly to reduce the speed and increase the torque of the motor.
Assuming the initial position of the servo motor shaft, the position of the potentiometer knob makes the output of the potentiometer not produce an electrical signal.
Now, an electrical signal is emitted to another input of the error detector amplifier.
Now, the difference between the two signals, one from the potentiometer and the other from other sources, will be processed in the feedback mechanism and output will be provided according to the error signal.
This error signal is used as the input for the start rotation of the motor and the motor.
Now, the motor shaft is connected to the potentiometer, which generates a signal when the motor rotates.
Therefore, when the angle position of the potentiometer changes, the output feedback signal will also change.
After that, the position of the potentiometer reaches the position where the potentiometer output is the same as the external signal provided.
In this case, there will be no output signal from the amplifier to the motor input, because there is no difference between the signal applied externally and the signal generated by the potentiometer, in which case the motor stops rotating.
Control Servo Motor: PWM is used for servo motor (
Pulse with modulation
This is provided by the control line.
There are minimum pulses, maximum pulses, and repetition rates.
The servo motor can rotate 90 degrees from either direction of its neutral position.
The servo motor is expected to have a pulse every 20 milliseconds (ms)
The length of the pulse will determine the distance the motor rotates.
For example, a 1.
The 5 MS pulse will turn the motor to 90 ° position, such as the pulse is less than 1.
If the axis is longer than 1, the 5 MS axis moves to 0 °.
5 ms faster than it turns the servo to 180 °.
The servo motor works in PWM (
Pulse width modulation)
Principle, that is, its rotation angle is controlled by the pulse duration applied to its control pin.
Basically, the servo motor is composed of a DC motor, which is controlled by variable resistance (potentiometer)and some gears.
The high-speed force of the DC motor is converted into torque through the gear.
We know that in a DC motor, the power = Force X distance is less than and distance (speed)
High, servo, High Force, small distance.
The potentiometer is connected to the output of the servo to calculate the angle and stop the DC motor at the required angle.
To sum up, there are two important differences between the control pulse of the servo motor and the DC motor.
I. about servo motor, duty cycle (on-time vs. off-time)
No sense-
What is important is the positive duration --
Pulse, corresponding to the command output position of the servo axis.
Second, the servo system has its own power electronics, so there is very little power flow on the control signal.
All power is drawn from its power, it must simply be connected to a high
A current source of 5 volts.
The continuous rotating servo motor is actually a modified version of what the servo system actually does, that is, the position of the control shaft.
The 360 ° rotary servo system is actually achieved by changing certain mechanical connections inside the servo system.
However, manufacturers like parallax also sell these servo systems.
With continuous rotary servo, you can only control the direction and speed of the servo, not the position.
The Arduino servo control servo motor has three lines: power supply, ground and signal.
The power cord is usually red and should be connected to the 5 v pin on the Arduino or Genuino board.
The ground wire is usually black or brown and should be attached to the ground pin on the board.
The signal pin is usually yellow, orange or white and should be connected to pin 9 on the board.
Code application: Advantages: limitations: movement and positioning accuracy of most RC servo systems limited to 180 degrees and /-
1 degree is typical.
You can find different types of servo motors in Sparkfun.
The coma stepping motor is a mechanical and electrical device that converts pulses into discrete mechanical motion.
When the electrical instruction pulse is applied to the stepping motor in the appropriate order, the shaft or spindle of the stepping motor rotates in discrete step increments.
The motor rotation has several direct relationships with these applied input pulses.
The order in which pulses are applied is directly related to the direction in which the motor shaft rotates.
The speed of the motor shaft rotation is directly related to the frequency of the input pulse, and the length of the rotation is directly related to the number of input pulses applied.
The stepping motor is a good motor for position control.
They can be found in desktop printers, draftsmen, 3d printers, CNC milling machines, and any equipment that requires precise position control.
The stepping motor is a special brushless motor.
They are designed for highholding torque. This high-
Keeping the torque allows the user to \"move forward\" to the next position step by step.
This leads to a simple positioning system that does not require an encoder.
This makes the construction and use of the stepping motor controller very simple.
One of the most significant advantages of the stepping motor is its ability to accurately control in the open-loop system.
Open loop control means no feedback about the location is required.
This type of control does not require expensive sensing and feedback devices such as optical encoders.
Just keep track of the input stepping pulse to know where you are.
What are the benefits of stepping motor?
The stepping motor can be a good choice whenever controlled motion is required.
They can play an advantage in applications that need to control the rotation angle, speed, position, and sync.
Positioning-since the stepping motors move in precise repeatable steps, they perform well in applications that require precise positioning, such as 3D printers, CNC, camera platforms and X, Y drafters
Some disk drives also use a stepping motor to locate the reader head.
Speed control-precise movement increments also allow excellent control over process automation and the rotation speed of the robot.
Low speed torque-
The normal DC motor does not have much torque at low speed.
Stepping motors have maximum torque at low speed, so they are a good choice for applications that require low speed and high accuracy.
The stepping motor works exactly the same as the brushless motor, but the step size is much smaller.
The only moving part is the rotor, which contains the magnet.
When things get complicated, the order of the excitation winding is arranged.
The polarity of each winding is controlled by the current direction.
The animation demonstrates the simple mode that the controller will follow.
The alternating current changes the polarity, giving each winding a \"push/pull\" effect.
A significant difference is how the magnet structure of the stepping motor is different.
It\'s hard to get a set of magnets to perform well on a small scale.
Expensive too.
To solve this problem, most step motors use the stacking board method to orient the poles into the \"teeth.
There are two types of stepping motor, single-pole type and double-pole type.
Fundamentally, the two types work exactly the same way;
Open the magnet in order to induce the rotation of the central motor shaft.
The difference between these two types is the voltage level.
The single-polar stepping motor works only under positive voltage, so the high and low voltage applied to the coil is similar to 5 v and 0 v.
The bipolar stepping motor has both positive and negative polarity, so its high and low voltage is like 2. 5V and -2. 5V.
Taking into account these electrical differences, the physical difference between the two approaches is that a single-pole configuration requires an additional wire in the middle of each coil to allow the current to flow through one end or the other of the coil.
These two opposite directions produce two polarity of the magnetic field, effectively simulating the positive and negative voltage capability of the bipolar stepping motor.
Although the voltage range of both motors is 5 v, the bipolar stepping motor will actually have more torque due to the current flowing through the entire coil, resulting in a strong magnetic field, rotate the axis to the right angle.
On the other hand, since there are additional wires in the middle of the coil, the single-pole stepping motor utilizes only half the length of the coil, so it is possible to keep the shaft in place with less torque.
The two-phase bipolar motor has two sets of coils.
There are 4 phase single polarity motors. A 2-
There will be 4 wires for the phase bipolar motor
2 in each stage.
Some motors come with flexible wiring that allows you to run the motor as a bipolar or single pole.
Driving the stepping motor is a little more complicated than driving the ordinary brush DC machine.
The stepping motor needs the stepping controller to give the connected electricity in time to make the motor turn.
There are several different driving modes for the stepping motor, including full step, half step and micro step.
Each drive mode provides different torque and step sizes that the stepping motor can use.
A full step drive always has two \"open\" magnets.
To rotate the center shaft, one of the magnets is closed and the next one is opened, causing the shaft to rotate 1/4 of the tooth (
Suitable for hybrid stepping motors at least).
This way of always opening two magnets has the largest torque in all styles, but the step size is the largest.
The half-step drive alternate between opening two magnets and one magnet.
To rotate the center shaft, the first magnet is powered on as the first step, and then the second is powered on as well, while the first is still powered on for the second step.
The third step is to turn off the first magnet, the fourth step is to turn on the third one, and the second one is still powered on.
The steps used in this mode shown in the above figure are twice the size of the entire step drive, allowing half the step size, however, it also has a smaller total torque, because there are not always two magnets that hold the center shaft in place.
It\'s no surprise that the microstep has the smallest step possible in these styles.
One of the most common methods of micro-stepping is to perform a \"sine-sine micro-stepping \".
This means that the current flowing through each coil is manipulated, resulting in a sine/Yu cosine.
The \"overlap\" of the waves between the two coils results in a large quantum step.
The actual number of substeps depends on how many different current changes you can provide to the coil, but the microstep will still have the smallest step size, so it is the most accurate movement, in all styles.
The torque associated with this approach depends on the current flowing through the coil at a specific time, but always less than the full step drive.
The simplest driver can be built with a small number of transistors.
These are simply turned on and off in sequence to motivate the phase and the stepping motor.
The manufacturing cost of the single-polar drive is relatively low, but only the single-polar motor can be used.
There is a good tutorial on how to build one on the Arduino website.
2 Complete H-is required to drive the bipolar motor-
This way it can reverse the current to phase. H-
Building bridges from scratch can be tricky.
But there\'s a lot of H-
Bridging chips that can be used to simplify tasks.
L293D is one of the most popular and economical chips.
These can be found in most of the first centers.
Generation motor shielding.
The following code segments can be used to control the stepping motor using the arduino board.
Application: Advantages: limitations: More details of the stepping motor: access Sparkfun for high-quality stepping motors and drives.
Choosing the motor that suits your task is one of the most important parts of planning the robot project.
The good news is that there are many types of motors to choose from, and as the joke says, the bad news is that there are many types of motors to choose from.
To choose the motor that suits your project, you should consider some important Motor Specifications: torque is a measure of the motor\'s ability to provide \"steering force.
In a robot, the motor torque is transmitted to the wheel or lever, which then causes the robot to move or raise, push, or pull something with a lever.
The torque is measured by the force multiplied by the vertical distance between the force and the point of rotation, I . E. e.
Shaft of motor.
It is usually given in ounces-inches (oz-inch), gram-centimeters (gm-cm)or foot-pounds (ft-lbs). Ounce-inches (oz-in)
Is the most common.
Estimating the required torque is a daunting task.
To determine the torque selected by the motor, we need to know the quality and friction of the load/Rover.
Obtaining quality estimates (
Even better actual quality)
It is essential to select the motor.
If you are designing based on a quality estimate, you should apply for a good profit for quality inflation.
Friction is a force, not the opposite of the movement between the two surfaces in contact with each other.
To measure torque accurately, you must consider static friction, dynamic friction, and rolling friction.
In order to drive the robot, the motor torque must at least overcome the external torque of the friction force acting on the wheel radius.
The required torque can be found using the following equation: T = 8 x C x W x Dwhere: friction changes from 0. 001 to 0. 03.
For example, for C = 0.
03, the minimum torque of a 5-pound robot with a moving diameter of 4 inch wheels is: T = 8x0.
03 × 5lb × 4in = 4. 8 oz-
Only when the torque is greater than the resultant force opposite the motion of the robot can the inA motor maintain a constant speed.
If the torque of the motor is less than the reverse torque, the motor will stop and may be damaged because the electric energy cannot be converted into torque.
After determining how much force/torque you need, the next step is to determine the speed at which the wheel needs to turn.
Speed requirements are easier to estimate, depending on the speed of the robot.
The DC motor operates at the speed of thousands of RPMs, with low torque, but the speed required by most robots is lower than that.
To move the robot, the output torque is too low.
So, this is not suitable for driving robots.
To use the motor, we added a gearbox to reduce the speed of the motor and increase the output torque.
The same motor may produce different torque and speed ratings, depending on the gear set used between the motor and the gearbox input shaft.
Many DC motors are equipped with a gear box that has been connected, which is simply called a DC gear motor, which is the type of motor.
By reducing the speed, you can also improve the position accuracy of the motor.
The speed, torque and precision of the gear motor are directly affected by the gear ratio as shown in the following equation: output speed = motor speed/gear ratio output accuracy = Motor accuracy/gear ratio although the deceleration ratio plays a big role in determining the output torque of the gearbox, it can also lead to inefficiency by using the gearbox.
Due to the friction between the gears, some torque of the motor is converted into heat and lost.
Another drawback is that the gear motor is not accurate.
That is to say, two motors of the same model, manufactured on the same day, run at the same current and voltage, do not turn at the exact same speed.
So without some way of controlling the speed of a single motor, a robot with two drive motors, the most common configuration, does not move in straight lines.
For the gearbox, torque and speed can be seen as an interchanging feature: If you need more torque and less speed, try to find the same motor with a lower deceleration ratio.
If you need more speed and less torque, try to find the same motor with a lower deceleration ratio.
However, it is not recommended to purchase the gearboxes and motors separately for mixing and matching unless they are specifically designed for each other.
There are a lot of problems with gearbox customization, and for most users, it\'s not that much trouble to simply buy a motor that has already connected the gearbox.
A major drawback is the inaccuracy of the gear head motor.
Some applications require very precise motion and angle, such as the robot arm and the plane control surface of the model.
Stepping motors and servo motors are most suitable for such applications.
The servo motor has internal position adjustment and slows down to achieve very precise position control.
The stepping motor moves step by step, using a magnetic field to move the motor in discrete increments.
According to the step size of the motor and the step mode of the controller stepping motor, extremely accurate position can be achieved.
The step angle of the stepping motor is usually as low as 1.
8 ° and Micro
The step controller can be further 1 out of 16 at a time.
The stepping motor also has the advantage of high holding torque
When the motor stops but is still powered on, it will hold its position firmly.
In general, the servo motor is smaller in size and less in torque than the stepping motor.
The range of motion of most servo systems is also limited.
The typical servo motor has a rotation range of 180 ° or less, although some motors are able to perform multiple rotations or even continuous rotations.
RC servo system is the most common (remote control)
Applications that do not require large torque or wide range of motion.
On the other hand, the stepping motor is used for applications that require extremely high precision or high torque. CNC (
Computer numerical control)
The machine is the main example of a stepping motor.
Some applications require high-speed and lightweight, such as multi-helicopter and drone, using an efficient brushless DC motor in this case.
Another important consideration is the operating voltage.
Before planning what battery pack to use in the project, you have to find the nominal voltage of the motor running, usually the higher the voltage, the higher the motor speed.
You can view the voltage constant from the motor data sheet to determine how fast you are per volt.
The most commonly used motor in robot projects is the DC motor.
The common preferred voltages for DC motors are 3, 6, 12 and 24 volts.
If the voltage applied to the motor is lower than the voltage heard in the data sheet, the torque will not overcome the internal friction-mainly from the brush.
In addition, if a higher voltage is applied to the motor than the support voltage, it may heat up and damage.
Most of the images of this structure are taken from the Internet.
Some topics, images, and text were copied from: 1. www. microchip.
Com/Please Don\'t forget to give me a friendly vote if you like this.
Robot developing human
To make a mechanical device that can be moved by itself, its motion must be modeled, planned, perceived, driven and controlled, and its motion behavior can be affected by \"programming.
This definition means that if the device contains a movable mechanism affected by sensing, planning, driving, and controlling components, it can only be called \"robot \".
The motor and the actuator are the devices that make the robot move.
The motor and the actuator convert electrical energy into physical motion.
The vast majority of actuators produce rotational or linear motion.
In this note, I will explain the more common types of motors and actuators, the fundamentals of them and how to control them.
You already know that an electric motor is used to \"drive\" something in a robot: its wheels, legs, tracks, arms, fingers, sensor turrets, cameras, or weapon systems.
There are dozens of types of electric Madas, but I will discuss the most common types of amateur robots.
The motor is classified as: AC (
AC current)
Motor is rarely used by mobile robots, because most robots are DC-powered (DC)
From the battery.
In addition, since the electronic components use DC, it is also more convenient to provide the same type of power supply for the actuator.
The AC motor is mainly used in industrial environments where very large torque is required, or in industrial environments where the motor is connected to a power/wall socket.
So I won\'t explain the AC motor here.
The motor controller is an electronic device that helps the micro-controller to control the motor.
The motor controller acts as an intermediate device between the micro-controller, power supply or battery and the motor.
Although the micro controller (
Brain of robot)
Determines the speed and direction of the motor, because its power is very limited, so they cannot be driven directly (
Current and voltage)output.
On the other hand, the motor controller can provide current at the required voltage, but cannot decide how the motor should operate.
Therefore, in order for the motor to move properly, the micro-controller and the motor controller must work together.
In general, the micro-controller can guide how the motor controller can power the motor through standard and simple communication methods (such as serial port or PWM.
In addition, some motor controllers can be manually controlled by analog voltage (
Usually created with potentiometer).
The physical size and weight of the motor controller may vary significantly, from the device used to control the mini Sumo robot less than the tip of the hand to the large controller weighing several kilograms.
The size of the motor controller is usually related to the maximum current it can provide.
A larger current means a larger size.
Since there are several types of motors, there are several types of motor controllers (
Different types of motors require different types of controllers)
: Brushed DC motor is a motor that uses two brushes to conduct current from the power supply to the stator.
There are several changes in the brush DC motor, but the permanent magnet DC motor (PMDC)
It is widely used in robot field.
Brushed DC motors are widely used from toys to push
Button adjustable car seat. Brushed DC (BDC)
The motor is cheap and easy to drive and is easy to buy in all sizes and shapes.
The brushed DC motor consists of six different components: the shaft, the stator/rotor, the diverter, the stator, the magnet and the brush.
The brushed DC motor consists of two magnets facing the same direction, which surround the two-ring wires located in the middle of the brushed DC motor and around the rotor.
The coil is placed on the surface of the magnet, causing the current to flow to the magnet.
This creates a magnetic field that eventually pushes the coils away from the magnet they face and causes the rotor to turn.
There are two terminals for Brushed DC motors;
When applying voltage on two terminals, the output proportional speed to the shaft of the brushed DC motor.
The brush DC motor consists of two parts: the stator of the housing, the permanent magnet and the brush and the rotor composed of the input shaft, the winding and the diverter.
The stator of the brush DC motor is stationary, while the rotor rotates relative to the brush DC motor stator.
The stator generates a static magnetic field around the rotor.
A rotor, also known as a rotor, consists of one or more windings.
When these windings are energized, they create a magnetic field.
The poles of this rotor magnetic field will be attracted by the opposite poles generated by the stator, resulting in the rotation of the rotor.
When the motor is turned, the winding is constantly energized in different order so that the Poles generated by the rotor do not exceed the Poles generated in the stator.
This switching of the magnetic field in the rotor winding is called phase change.
Different from other motor types (i. e.
DC, AC induction)
, The BDC motor does not need a controller to switch the current in the motor winding.
On the contrary, the phase change of the winding of the BDC motor is mechanically completed.
The segmented copper sleeve located on the shaft of the BDC motor is called a diverter.
When the motor is turned, the carbon brush slides over the diverter and is in contact with different parts of the diverter.
These segments are connected to different rotor windings, so when the voltage is applied to the brush of the motor, a dynamic magnetic field is generated inside the motor.
It is important to note that the brushes and switches are the most easily worn parts of the BDC motor because they slide each other.
Application: Advantages: limitations: in addition to the sound emitted by the electrical brush of the recharger, these motors produce a lot of electrical noise that goes back into other circuits and causes problems.
Access to the DC motor: What I am talking about is control of direction and speed.
By simply reversing the polarity of the battery connection, the direction of the DC motor can be reversed.
The speed of the motor can be controlled by changing the voltage level, and the DC voltage level can be changed through the PWM signal.
For higher voltage level speed will be higher and for lower voltage level speed will be lower.
In fact, drive circuits are used in applications that use some kind of controller and require speed control.
The purpose of the drive circuit is to give the controller a way to change the winding current of the BDC motor.
The driving circuit discussed in this section allows the controller pulse width modulation to supply the voltage to the BDC motor.
Compared with the traditional simulation control method, changing the speed of the BDC motor is a more effective method.
In some cases, the motor only needs to rotate in one direction, and then a single switch topology with PWM Modulation can be used to change the voltage applied to the motor to control its speed.
The higher the PWM duty cycle, the faster the motor will run.
The figure shows the circuit that drives the BDC motor in one direction using a single FET (
Field effect transistor).
Note that there is a diode on the motor in the circuit.
This diode is designed to prevent electricity on the back-netic Flux (BEMF)
Damage the voltage of the MOSFET.
BEMF is generated when the motor rotates.
When the MOSFET is turned off, the winding in the motor is still charging at this time and reverse current is generated.
The D1 must be properly rated to dissipate the current.
The resistors R1 and R2 in the figure are very important for the operation of the circuit.
R1 protects the microprocessor from current spikes, while R2 ensures that the transistor is off when the input pin is three-on.
When two directions of rotation are needed or need to be located (
Most robots are needed. afull H-
Use the bridge with PWM control. The H-Bridge is a 4-
A transistor circuit that allows you to reverse the current to the motor. With an H-
Bridge and PWM pins, you can control the speed and direction of the motor.
To understand, follow the next step.
The H-bridge is an electronic circuit that enables the voltage to be applied to the load in any direction.
These circuits are commonly used for robots and other applications to allow the DC motor to run forward and backward. An H-
The bridge is a transistor.
Based on the circuit that can drive the motor clockwise and anticlockwiseclockwise.
This is a very popular circuit-the driving force behind countless robots that must be able to move forward and backward.
Basically, an H.
The bridge is a combination of four transistors, two input lines and two outputs :(
Note: more often than not in a welldesigned H-
A bridge that includes an anti-excitation diode, a base resistor, and a Schmidt trigger. )
To understand this, H-
Both sides of the bridge should be broken, or halfbridges.
Half of the first and second quarters
The third and fourth quarters made up for the other half. bridge.
Half of these.
The bridge is able to switch one side of the BDC motor to either a power supply voltage or a potential to ground.
For example, when Q1 is on and Q2 is off, the left side of the motor will be at the potential of the supply voltage.
Turning Q4 on and off Q3 will ground the other side of the motor.
Switching elements (Q1. . Q4)are usually bi-
A transistor or FET transistor, at some height.
Voltage application igbt.
Pay attention to the diodes on each transistor (D1-D4).
When transistors are turned off, these Diodes Protect the transistors from current spikes generated by BEMF. The top-
The end of the bridge is connected to the power supply (
Battery, for example)and the bottom-The end is grounded.
Capacitors can be used in parallel with diodes.
But this is optional.
The values of these capacitors are generally within the range of 10pf.
The purpose of these capacitors is to reduce the RF radiation generated by the bending of the converter.
Basic operation mode of H-
The bridge is fairly simple: If Q1 and Q4 are turned on, the left lead of the motor will be connected to the power supply while the right lead will be connected to the ground.
The current begins to flow through the motor (let’s say)
The forward direction and the motor shaft begin to rotate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If Q2 and Q3 are turned on, the reverse will occur, the motor will be powered on in reverse, and the shaft will start to rotate backwards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
You should never close Q1 and Q2 on the bridge (or Q3 and Q4)
At the same time.
If you do, you just create a very low
Resistance path between power and GND, effectively shortening-
Your power circuit.
This situation is called \"shooting\"
This is a way to almost guarantee a quick destruction of your bridge or something else in the circuit.
H-there are many different models and brands
Bridging IC is available.
Most commonly used are Texas Instruments L293NE or Texas Instruments SN754410 and L298 from Italian semiconductor.
L293d L293NE/SN754410 is a very basic H-bridge.
It has two bridges, one on the left side of the chip and one on the right side, which can control two motors.
It can drive up to 1 amp of current and work between 4 amps. 5Vand 36V.
Small DC motors commonly used in robot robots can operate safely at low voltage
Bridge works very well. The H-
Bridge has the following pins and features: Keep in mind that all motors have different sizes.
Small motors are designed for applications with higher torque values.
Small high though-
Due to the use of rare earth magnets, efficient bearings and other features that increase costs, these connectors tend to be expensive.
Large motors can generate greater torque, but higher current is also required.
High-current motors require more large-capacity batteries and larger control circuits that do not overheat and burn out under load.
Therefore, match the size of the motor with the rest of the robot.
When the large size is not important, do not overload the small robot with a large motor.
When determining the size of the motor, compare the available torque after the gear slows down.
Gear deceleration always increases torque.
The increase in torque is proportional to the gear deceleration: If the deceleration is 3:1, the torque is increased by about three times (
But this is not the case due to friction loss). For H-
Please visit the bridge IC and Module: you already know that the DC motor cannot be connected directly to the arduino pin as it will burn your arduino.
So you have to connect the transistor between the arduino and the motor.
Let\'s first control a small DC motor using a single transistor.
All you know is that speed can be controlled.
PWM is used to control the speed of the DC motor.
Connection circuit as shown in figure-1.
The Arduino PWM pin must be connected to the base pin of the transistor.
Now, connect the motor with H-Bridge IC (
I\'m using L293 here). Follow Fig-3 & Fig-4.
We can now control the speed and direction.
Pin 9 is used as a PWM pin and a switch is added to control the speed.
L293 is a double H bridge IC.
So, you can control the two motors through a single IC.
Connect the two motors to the IC as shown in figure 5 and use the following code.
Make changes as per your requirements. .
The gear DC motor can be defined as an extension of the DC motor, which has previously been clarified for its insight details.
The gear assembly of the slow down DC motor is connected to the motor.
The speed of the motor is calculated according to the rotation of the shaft per minute, and calculated in RPM.
Gear assemblies help increase torque and reduce speed.
Using the correct gear combination in gear Madras, its speed can be reduced to any ideal number.
In this concept, the gear reduces the speed of the vehicle, but increases the torque, which is called Gear deceleration.
This insight will explore all the minor and major details that make the gear head and gear geared motor work.
The working DC motor of the DC deceleration motor works within a considerable voltage range.
The higher the input voltage, RPM (
Rotate per minute)of the motor.
For example, if the motor works at 6-
At 12 V, it will have a minimum RPM at 6 V and a maximum rpm at 12 V.
In terms of voltage, we can set the equation to: RPM = K1 * V where K1 = the induced voltage constant V = voltage applied.
It is very interesting to know the work of gears.
It can be explained by the principle of conservation of momentum.
The gear with a smaller radius is higher than the gear with a larger radius.
However, larger gears bring more torque to smaller gears and vice versa.
Comparison of input gear angular velocity (
The one that transmits energy)
The output gear gives the gear ratio.
When multiple gears are connected together, conservation of energy is also followed.
The direction of the rotation of the other gear is always opposite to the adjacent gear.
In any DC motor, the rotation speed and torque are inversely proportional.
Therefore, the gear with a large torque will provide a smaller rotation speed and speed.
In the gearedDC motor, the concept of pulse width modulation is applied.
For example, the unmounted DC motor can rotate at 12000 rpm and provide 0. 1 kg-cm of torque.
In order to reduce the speed and increase the torque proportionally, a 225:1 deceleration was added: 12000 rpm/225 = 53. 3 rpm and 0. 1 x225 = 22. 5 kg-cm.
Now the motor will be able to move more weight at a more reasonable speed.
In the gear DC motor, the gear connecting the motor and the gear head is very small, so it passes more speed to the larger tooth part of the gear head and makes it rotate.
The larger part of the gear further turns the smaller duplex part.
The small duplex section receives the speed of torquebut not from its predecessors it transfers to the largerpart of other gears and so on.
The duplex part of the third gear has more teeth than the other parts, so it will pass more torque to the gear connected to the shaft.
The control of the gear reduction motor can be exactly the same as that of the DC motor.
Application: Advantages: limitations: This is especially low
Plastic gear train used with low costvoltage motors.
Additional resistance can make these gears
Low speed train.
For controller and motor browsing: www. sparkfun.
DC (BLDC)
There are many kinds of motor names, such as: brushless permanent magnet motor, permanent magnet AC motor, permanent magnet synchronous motor, etc.
This confusion occurs because the DC motor cannot operate directly from the DC voltage source.
However, as we will see, the basic working principle is similar to the DC motor.
The BLDC has a rotor with a permanent magnet and a stator with winding.
It is essentially a DC motor that rotates from the inside out.
The brush and the diverter have been eliminated and the winding is connected to the control electronics.
Control the function of the electronic device to replace the converter and power up the appropriate winding.
As shown in the animation, the winding is powered on in a pattern that rotates around the stator.
The energized stator winding guides the rotor magnet and switches when the rotor is aligned with the stator.
No sparks, this is an advantage of the BLDC motor.
There are several restrictions on the brush of the DC motor;
Brush life, brush residual, maximum speed, electric noise.
The BLDC motor may be cleaner, faster, more efficient, less noisy and more reliable.
However, electronic control is required for the BLDC motor.
Then, the structure of the brushless DC motor is very similar to the AC motor, making it a real synchronous motor, but one drawback is that it is more expensive than the equivalent \"brushed\" motor design.
There are two types of brushless RC motor, brushless RC motor and brushless RC motor.
The permanent magnet of the Inrunner brushless motor is located inside the magnet.
The exterior of the Outrunner brushless motor has a permanent magnet.
The faster the motor speed, the higher the efficiency.
The Inrunner motor rotates very fast and is much more efficient than the outrunner motor.
The Inrunner brushless RC motor needs to install a deceleration gearbox between the motor and the propeller of the RC aircraft.
The disadvantage of Inrunner is the additional parts that can and do fail.
The gear is stripped and the shaft of the gearbox is easily bent.
This can also be an obstacle when you are neatly installing the gearbox motor combination of the RC aircraft, especially under the shield.
Operation theory the mechanical principle of brushless motor is very simple.
The only moving part is the rotor, which contains the magnet.
When things get complicated, the order of the excitation winding is arranged.
The polarity of each winding is controlled by the current direction.
The animation demonstrates the simple mode that the controller will follow.
The alternating current changes the polarity, giving each winding a \"push/pull\" effect.
The trick is to keep this mode in sync with the speed of the rotor. There are two (widely used)
This can be achieved.
Most hobby controllers measure the voltage generated (back EMI)on the un-
Power-on winding.
This method is very reliable when running at high speed.
As the speed of the motor decreases, the resulting voltage becomes more difficult to measure and more errors are generated.
Newer hobby controllers and many industrial controllers use Hall sensors to measure the position of the magnet directly.
This is the main way to control the computer fan.
The control of the brushless DC motor is very different from that of the ordinary brushed DC motor, because this type of motor contains some methods to detect the angle position of the rotor (
Or magnetic poles)
Used to generate feedback signals needed to control semiconductor switching devices.
Hall sensors are the most common position/electrode sensors, but there are also some motors that use optical sensors.
Using the hall sensor, the motor controls the polarity of the drive circuit to switch the magnet.
The motor can then be easily synchronized with the digital clock signal, thus providing precise speed control.
It can be constructed as a brushless DC motor with an external permanent magnet rotor and an internal magnet stator or an internal permanent magnet rotor and an external magnet stator. In figure 4 (A)
, The Green winding marked \"001\" is energized as the Arctic, and the blue winding marked \"010\" is energized as the Antarctic.
Due to this excitation, the Antarctic of the rotor is aligned with the Green winding, and the Arctic is aligned with the red winding marked \"100.
To move the rotor, the \"red\" and \"blue\" windings are energized in the direction shown in Figure 4 (B).
This caused the red winding to become the Arctic, and the blue winding to become the Antarctic.
Due to the development of rejection force, this change in the stator magnetic field produces torque (
North-red windingNorth alignment)
And attraction (
Blue winding northSouth alignment)
Make the rotor move clockwise.
In fact, the DC motor is a three-phase AC motor.
Speed is controlled using electronic speed control or ESC.
The Brushless ESC system basically creates a three
Phase AC power supply with limited voltage input and output from onboard DC power supply, run the brushless motor by sending a series of AC signals generated from the ESC circuit, using a very low rotational impedance.
According to its physical configuration, the brushless motor is called the Super run motor or the inrunners motor, which is very popular in the \"electric flight\" Radio
Compared with the traditional Brush Motor, its efficiency, power, life and weight are very small, so the pneumatic roller brush enthusiasts can be controlled.
However, the brushless AC motor controller is much more complex than the brushed motor controller.
The correct phase changes as the motor rotates, and ESC will take this into account: Normally, the back potential of the motor is used to detect this rotation, but changes in the use of magnetism are present (Hall Effect)
Or optical detectors. Computer-
There are usually users with programmable speed control-
Allow setting the specified option for low voltage cut-
Limit, timing, acceleration, braking and direction of rotation.
By switching any two of the three leads from ESC to the motor, the direction of the motor can also be reversed.
The current rating of the ESCAn ESC will have a power limit.
ESC needs to be larger, heavier, and more expensive to handle more power supplies.
It is important to know the peak current of your motor at full throttle.
This determines the current rating you should look for in ESC.
Always select ESC with a current rating higher than you need.
If the car is about to pull 12A, 25A-
Rated ESC is a better choice than 10Arated one.
Even if you only fly under a half throttle, 10A ESC can overheat and Cook.
The ESCs are relatively light and maintain a high resale value, so this is a project in your power system that is not worth wasting time.
Choosing the right type and identifying the minimum current rating are two steps.
The next choice depends on your preference.
All ESCs have voltage limits.
Some people even have more than one!
What is your battery voltage?
Select ESC designed to work at the same or higher voltage.
Some ESCs are designed for low voltage (below 13V)
Some for medium voltage (below 25V)
, Some for high voltage (above 25V).
You should not connect the high voltage battery to the low voltage ESC, but it is also a waste to use the high voltage ESC with the low voltage battery.
Compared with the \"brush\" motor, the advantages of the DC motor are higher efficiency, high reliability, low electrical noise, good speed control, and more importantly, there is no wear of the brush or the changer that produces a higher speed.
Their downside, however, is that they are more expensive and more complex to control.
Arduino controls the brushless motor designed for automatic and remote control aircraft and vehicles often require separate controllers.
They are typically sensor-free types and speed control using pulse signals of the standard servo type.
It is very simple to control the BLDC motor.
Most ESCs require a frequency of 50 hz I. e.
The cycle and speed of the A20 MS depend on the duty cycle you provide.
1 mswill reduce its speed to a minimum or even stop (
It depends on the ESCmodel)
The 2 ms pulse will run the motor at its maximum speed.
The value between them gives you a change in speed.
Usually ESCs need to be higher than the voltage provided by Arduino from his 5 v pin: Usually they need 2 LiPo cells (around 8V).
In order to achieve this, all circuits must be powered by an external power supply directly connected to ESC instead of via Arduino, which will be powered by ESC\'s BEC circuit.
To do this, it is enough to connect the red and black of the control connector to the 5 v and GDN of the Arduino board.
The rest of the circuit is very easy: the voltage reading of the potentiometer comes in from the Arduino\'s pin 9 to ESC\'s signal, and then to pin 0.
Sometimes ESC needs to be calibrated, and in the case of ESCs, calibration means setting the maximum and minimum speed of the motor based on the maximum and minimum width of the PWM signal sent by Arduino.
The PWM signal read by ESC is the same type as the servo signal, which means that the servo Library from Adruino can be used to calibrate and control the ESCs.
ESC sets the speed of the motor according to the ratio of the high flow signal.
Calibration includes programming ESC to understand the pwm wave corresponding to the motor stop and maximum speed.
The default signal range for most servo motors and ESCs is the high signal width between 1000 and 2000 microseconds in a repeat period of 20 milliseconds (
Assuming a PWM signal of 50 hz).
For the four helicopters, however, we would like the range to be as wide as possible in order to have greater incremental control over the motor.
To do this, we calibrated the ESCs to read the signal width at a stop speed of 700 and a maximum speed of 700 from 2000 to 2000 microseconds.
Some ESC cannot read signals below 700 microseconds.
Calibration of ESCs is very simple.
To enter the programming mode, the maximum servo signal (
2000 microseconds)
Send to ESC, ESC power up and wait for two seconds, then send the minimum servo signal (
700 microseconds).
Once a series of confirmed beeps are issued by ESC (
Send a special waveform signal to the motor to make a beep sound)
, ESC calibration (
See ESC specific data tables for details).
It just needs to read \"throttle\" from 0-1023 to 0-179 (
Analog reading of servo \"degree)
Then send to ESC through the servo Library.
Even if it\'s very simple, this sketch is very useful when you want to calibrate a new ESC to use the Arduino\'s servo Library.
Application: Advantages: limitations: individual controllers are required for certain types of brushless motors to operate.
For a brushless DC motor, a visual servo motor is an electrical device that can push or rotate objects very precisely.
If you want to rotate and object at a specific angle or distance, then you can use a servo motor.
It is just made up of simple motors running through a servo mechanism.
If a DC-driven motor is used, then it is called a DC servo motor, and if it is an AC-driven motor, then it is called an AC servo motor.
We can get a very high torque servo motor in a small and light package.
According to these features, they are used in many applications such as toy cars, remote control helicopters and aircraft, robots, machines, etc.
The position of the servo motor is determined by the pulse, and its circuit is placed next to the motor.
Today\'s servo system has huge industrial applications.
The application of servo motors is also very common in remote control toy cars, used to control the direction of movement, and also very often used in the motor of moving CD or DVD player tray.
In addition, we can see hundreds of other servo motor applications in our daily life.
The main reason for using the servo system is that it provides angle accuracy. e.
It will only spin as we want and then stop and wait for the next signal to take further action.
This is different from the normal motor, which starts to rotate when it is applied to it, and the rotation continues until we turn off the power.
We cannot control the progress of the motor;
But we can only control the speed of the rotation and turn it on and off.
The servo mechanism consists of three parts: it is a closed loop system that uses a positive feedback system to control the movement and final position of the shaft.
Here, by comparing the output signal and the reference input signal, the device is controlled by the feedback signal.
The reference input signal is compared with the reference output signal here, and the third signal is generated by the feedback system.
The third signal is used as the input signal of the control device.
As long as there is a difference between the feedback signal or the reference input signal and the reference output signal, this signal exists.
Therefore, the main task of the servo system is to keep the output of the system at the expected value in the presence of noise.
Working Principle of Servo Motor (DC or AC)
, Potentiometer, gear assembly and control circuit.
First, we use the gear assembly to reduce the speed and increase the torque of the motor.
Assuming the initial position of the servo motor shaft, the position of the potentiometer knob makes the output of the potentiometer not produce an electrical signal.
Now, an electrical signal is emitted to another input of the error detector amplifier.
Now, the difference between the two signals, one from the potentiometer and the other from other sources, will be processed in the feedback mechanism and output will be provided according to the error signal.
This error signal is used as the input for the start rotation of the motor and the motor.
Now, the motor shaft is connected to the potentiometer, which generates a signal when the motor rotates.
Therefore, when the angle position of the potentiometer changes, the output feedback signal will also change.
After that, the position of the potentiometer reaches the position where the potentiometer output is the same as the external signal provided.
In this case, there will be no output signal from the amplifier to the motor input, because there is no difference between the signal applied externally and the signal generated by the potentiometer, in which case the motor stops rotating.
Control Servo Motor: PWM is used for servo motor (
Pulse with modulation
This is provided by the control line.
There are minimum pulses, maximum pulses, and repetition rates.
The servo motor can rotate 90 degrees from either direction of its neutral position.
The servo motor is expected to have a pulse every 20 milliseconds (ms)
The length of the pulse will determine the distance the motor rotates.
For example, a 1.
The 5 MS pulse will turn the motor to 90 ° position, such as the pulse is less than 1.
If the axis is longer than 1, the 5 MS axis moves to 0 °.
5 ms faster than it turns the servo to 180 °.
The servo motor works in PWM (
Pulse width modulation)
Principle, that is, its rotation angle is controlled by the pulse duration applied to its control pin.
Basically, the servo motor is composed of a DC motor, which is controlled by variable resistance (potentiometer)and some gears.
The high-speed force of the DC motor is converted into torque through the gear.
We know that in a DC motor, the power = Force X distance is less than and distance (speed)
High, servo, High Force, small distance.
The potentiometer is connected to the output of the servo to calculate the angle and stop the DC motor at the required angle.
To sum up, there are two important differences between the control pulse of the servo motor and the DC motor.
I. about servo motor, duty cycle (on-time vs. off-time)
No sense-
What is important is the positive duration --
Pulse, corresponding to the command output position of the servo axis.
Second, the servo system has its own power electronics, so there is very little power flow on the control signal.
All power is drawn from its power, it must simply be connected to a high
A current source of 5 volts.
The continuous rotating servo motor is actually a modified version of what the servo system actually does, that is, the position of the control shaft.
The 360 ° rotary servo system is actually achieved by changing certain mechanical connections inside the servo system.
However, manufacturers like parallax also sell these servo systems.
With continuous rotary servo, you can only control the direction and speed of the servo, not the position.
The Arduino servo control servo motor has three lines: power supply, ground and signal.
The power cord is usually red and should be connected to the 5 v pin on the Arduino or Genuino board.
The ground wire is usually black or brown and should be attached to the ground pin on the board.
The signal pin is usually yellow, orange or white and should be connected to pin 9 on the board.
Code application: Advantages: limitations: movement and positioning accuracy of most RC servo systems limited to 180 degrees and /-
1 degree is typical.
You can find different types of servo motors in Sparkfun.
The coma stepping motor is a mechanical and electrical device that converts pulses into discrete mechanical motion.
When the electrical instruction pulse is applied to the stepping motor in the appropriate order, the shaft or spindle of the stepping motor rotates in discrete step increments.
The motor rotation has several direct relationships with these applied input pulses.
The order in which pulses are applied is directly related to the direction in which the motor shaft rotates.
The speed of the motor shaft rotation is directly related to the frequency of the input pulse, and the length of the rotation is directly related to the number of input pulses applied.
The stepping motor is a good motor for position control.
They can be found in desktop printers, draftsmen, 3d printers, CNC milling machines, and any equipment that requires precise position control.
The stepping motor is a special brushless motor.
They are designed for highholding torque. This high-
Keeping the torque allows the user to \"move forward\" to the next position step by step.
This leads to a simple positioning system that does not require an encoder.
This makes the construction and use of the stepping motor controller very simple.
One of the most significant advantages of the stepping motor is its ability to accurately control in the open-loop system.
Open loop control means no feedback about the location is required.
This type of control does not require expensive sensing and feedback devices such as optical encoders.
Just keep track of the input stepping pulse to know where you are.
What are the benefits of stepping motor?
The stepping motor can be a good choice whenever controlled motion is required.
They can play an advantage in applications that need to control the rotation angle, speed, position, and sync.
Positioning-since the stepping motors move in precise repeatable steps, they perform well in applications that require precise positioning, such as 3D printers, CNC, camera platforms and X, Y drafters
Some disk drives also use a stepping motor to locate the reader head.
Speed control-precise movement increments also allow excellent control over process automation and the rotation speed of the robot.
Low speed torque-
The normal DC motor does not have much torque at low speed.
Stepping motors have maximum torque at low speed, so they are a good choice for applications that require low speed and high accuracy.
The stepping motor works exactly the same as the brushless motor, but the step size is much smaller.
The only moving part is the rotor, which contains the magnet.
When things get complicated, the order of the excitation winding is arranged.
The polarity of each winding is controlled by the current direction.
The animation demonstrates the simple mode that the controller will follow.
The alternating current changes the polarity, giving each winding a \"push/pull\" effect.
A significant difference is how the magnet structure of the stepping motor is different.
It\'s hard to get a set of magnets to perform well on a small scale.
Expensive too.
To solve this problem, most step motors use the stacking board method to orient the poles into the \"teeth.
There are two types of stepping motor, single-pole type and double-pole type.
Fundamentally, the two types work exactly the same way;
Open the magnet in order to induce the rotation of the central motor shaft.
The difference between these two types is the voltage level.
The single-polar stepping motor works only under positive voltage, so the high and low voltage applied to the coil is similar to 5 v and 0 v.
The bipolar stepping motor has both positive and negative polarity, so its high and low voltage is like 2. 5V and -2. 5V.
Taking into account these electrical differences, the physical difference between the two approaches is that a single-pole configuration requires an additional wire in the middle of each coil to allow the current to flow through one end or the other of the coil.
These two opposite directions produce two polarity of the magnetic field, effectively simulating the positive and negative voltage capability of the bipolar stepping motor.
Although the voltage range of both motors is 5 v, the bipolar stepping motor will actually have more torque due to the current flowing through the entire coil, resulting in a strong magnetic field, rotate the axis to the right angle.
On the other hand, since there are additional wires in the middle of the coil, the single-pole stepping motor utilizes only half the length of the coil, so it is possible to keep the shaft in place with less torque.
The two-phase bipolar motor has two sets of coils.
There are 4 phase single polarity motors. A 2-
There will be 4 wires for the phase bipolar motor
2 in each stage.
Some motors come with flexible wiring that allows you to run the motor as a bipolar or single pole.
Driving the stepping motor is a little more complicated than driving the ordinary brush DC machine.
The stepping motor needs the stepping controller to give the connected electricity in time to make the motor turn.
There are several different driving modes for the stepping motor, including full step, half step and micro step.
Each drive mode provides different torque and step sizes that the stepping motor can use.
A full step drive always has two \"open\" magnets.
To rotate the center shaft, one of the magnets is closed and the next one is opened, causing the shaft to rotate 1/4 of the tooth (
Suitable for hybrid stepping motors at least).
This way of always opening two magnets has the largest torque in all styles, but the step size is the largest.
The half-step drive alternate between opening two magnets and one magnet.
To rotate the center shaft, the first magnet is powered on as the first step, and then the second is powered on as well, while the first is still powered on for the second step.
The third step is to turn off the first magnet, the fourth step is to turn on the third one, and the second one is still powered on.
The steps used in this mode shown in the above figure are twice the size of the entire step drive, allowing half the step size, however, it also has a smaller total torque, because there are not always two magnets that hold the center shaft in place.
It\'s no surprise that the microstep has the smallest step possible in these styles.
One of the most common methods of micro-stepping is to perform a \"sine-sine micro-stepping \".
This means that the current flowing through each coil is manipulated, resulting in a sine/Yu cosine.
The \"overlap\" of the waves between the two coils results in a large quantum step.
The actual number of substeps depends on how many different current changes you can provide to the coil, but the microstep will still have the smallest step size, so it is the most accurate movement, in all styles.
The torque associated with this approach depends on the current flowing through the coil at a specific time, but always less than the full step drive.
The simplest driver can be built with a small number of transistors.
These are simply turned on and off in sequence to motivate the phase and the stepping motor.
The manufacturing cost of the single-polar drive is relatively low, but only the single-polar motor can be used.
There is a good tutorial on how to build one on the Arduino website.
2 Complete H-is required to drive the bipolar motor-
This way it can reverse the current to phase. H-
Building bridges from scratch can be tricky.
But there\'s a lot of H-
Bridging chips that can be used to simplify tasks.
L293D is one of the most popular and economical chips.
These can be found in most of the first centers.
Generation motor shielding.
The following code segments can be used to control the stepping motor using the arduino board.
Application: Advantages: limitations: More details of the stepping motor: access Sparkfun for high-quality stepping motors and drives.
Choosing the motor that suits your task is one of the most important parts of planning the robot project.
The good news is that there are many types of motors to choose from, and as the joke says, the bad news is that there are many types of motors to choose from.
To choose the motor that suits your project, you should consider some important Motor Specifications: torque is a measure of the motor\'s ability to provide \"steering force.
In a robot, the motor torque is transmitted to the wheel or lever, which then causes the robot to move or raise, push, or pull something with a lever.
The torque is measured by the force multiplied by the vertical distance between the force and the point of rotation, I . E. e.
Shaft of motor.
It is usually given in ounces-inches (oz-inch), gram-centimeters (gm-cm)or foot-pounds (ft-lbs). Ounce-inches (oz-in)
Is the most common.
Estimating the required torque is a daunting task.
To determine the torque selected by the motor, we need to know the quality and friction of the load/Rover.
Obtaining quality estimates (
Even better actual quality)
It is essential to select the motor.
If you are designing based on a quality estimate, you should apply for a good profit for quality inflation.
Friction is a force, not the opposite of the movement between the two surfaces in contact with each other.
To measure torque accurately, you must consider static friction, dynamic friction, and rolling friction.
In order to drive the robot, the motor torque must at least overcome the external torque of the friction force acting on the wheel radius.
The required torque can be found using the following equation: T = 8 x C x W x Dwhere: friction changes from 0. 001 to 0. 03.
For example, for C = 0.
03, the minimum torque of a 5-pound robot with a moving diameter of 4 inch wheels is: T = 8x0.
03 × 5lb × 4in = 4. 8 oz-
Only when the torque is greater than the resultant force opposite the motion of the robot can the inA motor maintain a constant speed.
If the torque of the motor is less than the reverse torque, the motor will stop and may be damaged because the electric energy cannot be converted into torque.
After determining how much force/torque you need, the next step is to determine the speed at which the wheel needs to turn.
Speed requirements are easier to estimate, depending on the speed of the robot.
The DC motor operates at the speed of thousands of RPMs, with low torque, but the speed required by most robots is lower than that.
To move the robot, the output torque is too low.
So, this is not suitable for driving robots.
To use the motor, we added a gearbox to reduce the speed of the motor and increase the output torque.
The same motor may produce different torque and speed ratings, depending on the gear set used between the motor and the gearbox input shaft.
Many DC motors are equipped with a gear box that has been connected, which is simply called a DC gear motor, which is the type of motor.
By reducing the speed, you can also improve the position accuracy of the motor.
The speed, torque and precision of the gear motor are directly affected by the gear ratio as shown in the following equation: output speed = motor speed/gear ratio output accuracy = Motor accuracy/gear ratio although the deceleration ratio plays a big role in determining the output torque of the gearbox, it can also lead to inefficiency by using the gearbox.
Due to the friction between the gears, some torque of the motor is converted into heat and lost.
Another drawback is that the gear motor is not accurate.
That is to say, two motors of the same model, manufactured on the same day, run at the same current and voltage, do not turn at the exact same speed.
So without some way of controlling the speed of a single motor, a robot with two drive motors, the most common configuration, does not move in straight lines.
For the gearbox, torque and speed can be seen as an interchanging feature: If you need more torque and less speed, try to find the same motor with a lower deceleration ratio.
If you need more speed and less torque, try to find the same motor with a lower deceleration ratio.
However, it is not recommended to purchase the gearboxes and motors separately for mixing and matching unless they are specifically designed for each other.
There are a lot of problems with gearbox customization, and for most users, it\'s not that much trouble to simply buy a motor that has already connected the gearbox.
A major drawback is the inaccuracy of the gear head motor.
Some applications require very precise motion and angle, such as the robot arm and the plane control surface of the model.
Stepping motors and servo motors are most suitable for such applications.
The servo motor has internal position adjustment and slows down to achieve very precise position control.
The stepping motor moves step by step, using a magnetic field to move the motor in discrete increments.
According to the step size of the motor and the step mode of the controller stepping motor, extremely accurate position can be achieved.
The step angle of the stepping motor is usually as low as 1.
8 ° and Micro
The step controller can be further 1 out of 16 at a time.
The stepping motor also has the advantage of high holding torque
When the motor stops but is still powered on, it will hold its position firmly.
In general, the servo motor is smaller in size and less in torque than the stepping motor.
The range of motion of most servo systems is also limited.
The typical servo motor has a rotation range of 180 ° or less, although some motors are able to perform multiple rotations or even continuous rotations.
RC servo system is the most common (remote control)
Applications that do not require large torque or wide range of motion.
On the other hand, the stepping motor is used for applications that require extremely high precision or high torque. CNC (
Computer numerical control)
The machine is the main example of a stepping motor.
Some applications require high-speed and lightweight, such as multi-helicopter and drone, using an efficient brushless DC motor in this case.
Another important consideration is the operating voltage.
Before planning what battery pack to use in the project, you have to find the nominal voltage of the motor running, usually the higher the voltage, the higher the motor speed.
You can view the voltage constant from the motor data sheet to determine how fast you are per volt.
The most commonly used motor in robot projects is the DC motor.
The common preferred voltages for DC motors are 3, 6, 12 and 24 volts.
If the voltage applied to the motor is lower than the voltage heard in the data sheet, the torque will not overcome the internal friction-mainly from the brush.
In addition, if a higher voltage is applied to the motor than the support voltage, it may heat up and damage.
Most of the images of this structure are taken from the Internet.
Some topics, images, and text were copied from: 1. www. microchip.
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