Source: http://www.societyofrobots.com/Reproduced from inkel.roboticfan.com drive, as the name suggests from the driver. It is a device that automatically operates other objects. It includes the following types: AC motor: AC. DC motor: use DC for ease of use. Brushless motor: DC motor without brush, better than ordinary DC motor, but the price is much more expensive. Used as a waterproof servo motor linear motor: can be used as a X-Y Plane Motion of the brushless motor. Servo Motor: A Basic DC motor with feedback control, which can be used easily. Adjustable servo motor: The servo motor can be adjusted for 360 degrees of rotation. SMA filaments (shape memory alloy, shape memory alloy,) are made of special materials. The shape of a sma filament changes when it is loaded, such as temperature or power-on. Solenoid: High-torque switch type for high-speed push/pull action drive, that is, relays. Stepper motor: a motor that operates in the form of incremental rotation. 1. Unlike the DC motor, the AC motor only uses a single constant current power supply. The AC motor works under three-phase electric currents. To allow the robot to work at three-phase currents, you may need a large-capacity, expensive converter that converts DC to AC power, or a wall outlet with a limited working range. You may not plan to use an AC motor unless your robot is fixed, just like a robot or a robot platform. If you are not planning to move the robot platform around like a puppy or something else... Voltage:
Polarity (current will not change)
It is mainly from 120-240v AC, which is generally matched with the host power.
Higher Voltage, larger torque, but larger power
Because the power supply equipment is less required for Mobile Robots
Note: The AC/DC motor has a brush like a DC motor, but it can be AC or DC
Current
When purchasing a motor, consider the shutdown and operating current (maximum and minimum)
Stop current-current required when the motor is controlled and cannot be rotated
Running current: Current when the motor is at zero torque
It is best to measure the current curve related to the voltage, current and required torque for optimization.
When the load torque of the motor changes, such as the motor reversal, it is expected to withstand short-term peak current
The current peak can reach twice the hold current. If there is no protection device, the control circuit will be damaged.
Use diodes to prevent reverse current from damaging your circuit
Check the rated power of your circuit and use a heat sink if needed
Power (that is, voltage multiplied by current)
Motor Running is often close to the stop current, or the reverse current under high torque, may cause the motor to burn out
If not, use a motor with a heat sink.Torque
When purchasing a motor, consider the stall and working torque (maximum and minimum)
Hold torque-torque when the power is insufficient to maintain motor Rotation
Working torque-motor torque when the motor's Yin torque is zero
Speed
Maximum speed effective during motor operation
The drive can make the motor turn faster. The lower the output speed, the larger the torque.
Remember that the torque determines the acceleration. Therefore, a high-speed robot with poor acceleration is actually a low-speed robot.
If you are not sure, You 'd better consider the torque over speed.
Efficiency
Higher efficiency than DC Motor
Generally, the rated voltage and frequency have the highest aging rate.
Use gear (optional, purchase a motor with built-in gear or gear outside)
Control Method
Adjusting the AC frequency can change the speed and torque.
An Encoder, used to count the number of turns on a wheel or motor shaft and determine the speed to control the feedback ring.
A device used to measure the maximum current of a motor to control the output torque.This circuit allows you to control the speed of the AC motor. The bridge rectifier generates DC voltage from the 120v AC line. A portion of this current is passed through a 10 k ohm potentiometer. The circuit consists of a 10 k potentiometer with a rated power of 3 W +, two 100 ohm resistors, and 50 micro capacitors, and is transferred to the control pole to trigger the thyristor. Diode D1 protection circuit from reverse peak voltage. The rated value of the bridge-type rectifier and thyristor is 25 amps and the peak reverse voltage (PIV) is 600 volts. The diode D1 rated value is 2 amps, while the peak reverse voltage is 600 volts. The circuit can handle up to 10 amps of load. The Thyristor should have a good heat sink. Source: http://www.societyofrobots.com/from the very beginning, DC motor is very simple. When the two ends are added with voltage, it turns. If you want to control the direction of motor rotation? The correct method is to change the direction of the wire. If you want the motor to rotate at half the speed? You should reduce its voltage. But how do you enable robots to automatically do this? And how do you know how much voltage the motor should receive? Why is it 12 V instead of 50 V? How can a motor be overheated? It is much more complicated to make the motor run than you think. You may know that the voltage of a DC motor is not two poles, that is, the voltage you can switch will not have any adverse situation. General DC motor is rated voltage from 6 V ~ 12 V. The larger value is 24 V or larger. But for robots, you may only use 6 V ~ 12 V range. In this case, why does the motor work at different voltages? As far as we know (or should be), the voltage is directly related to the motor torque. The higher the voltage, the higher the torque. But it won't be good if you don't want your motor to work v. The DC motor has the highest efficiency under rated voltage. If you use a low voltage value, it will not work. If you use a high voltage, it will overheat and the coil will melt. Therefore, the general rule is to try to use voltage close to the rated motor. In addition, although the 24 V motor will be more powerful, do you really want your robot to carry the 24 V battery with you (that is heavy and big )? My advice is not to exceed 24 V motor, unless you really need that torque too much. The current must be noticed for all circuits. Too small to work. If it is too large, it will be completely destroyed. When buying a motor, you must pay attention to two current ratings. The first is the operating current, which is the average current when the motor is working in the expected general torque. Multiply this value by the rated voltage to get the average power of the motor. Another noteworthy current rating is the stop current. This is where you start the motor but the torque is insufficient so that it stops rotating. This is the maximum current of the motor, and thus the maximum power. So you have designed all the circuits to handle such a stopped current. In addition, if you plan to run the motor for a long time, or when the voltage is higher than the rated voltage, it is best to add a heat sink to the motor to avoid coil melting. How high is the rated voltage added to the motor? Generally, all motors are limited by (or at least) a certain Watt. Watt is the energy unit. The loss in energy conversion directly changes to heat output. Too much heat will melt the motor coil (insulation part. So (high quality) motor manufacturers know how much voltage will make the motor failure, and give instructions in the motor performance table. Perform an experiment and test to see how much current your motor is working at the right voltage. Equation: Power (w) = Voltage * The current continuously increases the voltage and the test current until the power is about 90% of the given rated power.
. Peak power
Special circumstances when the direction of the DC motor is changed. To reverse the motor, you must also reverse the voltage. However, the motor has established an induction force to resist this voltage change. Therefore, changing the motor steering in a short period of time will have a large peak power. When the voltage is twice the operating voltage, the current is also switched to the stopped current. It is necessary to consider designing an appropriate robot power adjustment circuit to handle arbitrary voltage peaks. When purchasing a DC motor, pay attention to the two torque ratings. The first is the working torque, which is determined during the design of the motor, generally the nominal value. Another rated value is the stop torque, which is the torque from the motor to the stop. Generally, only the working torque is considered, but in some cases, you may want to know the working capacity range of the motor. If you design a wheeled robot, good torque means good acceleration performance. My personal standard is that if your robot has 2 motors, make sure that the torque of each motor is enough to exceed the weight of your robot multiplied by the wheel radius. Generally, torque is preferred over speed. Remember, as described above, the torque can be changed with the added voltage. If you need to press a cute kitten with a higher torque, it is safe to increase the voltage by 20% (for you, not the kitten ). But remember, this will reduce efficiency and you should prepare a heat sink for the motor. When it comes to a DC motor, the speed is complicated. The general rule is that when the motor runs at the maximum possible speed, the maximum aging rate is reached. However, this is obviously impossible. In many cases, we want our robots to run slowly. Therefore, the first thing we need to do is speed control, so that the motor can be quickly converted and can also get additional torque. Unfortunately, the transmission device automatically reduces the efficiency and will not exceed 90%. Therefore, when considering the transmission device, A pair of gear meshing should include a speed and torque reduction of 90%. For example, if there are three gears, so two meshing times together, the efficiency will be: 90% x 90% = 81%. The voltage and working Resistance Torque also significantly affect the speed. The main control method of DC motor is H Bridge. When you connect the H-bridge to the motor, you need to use a decoder to test the speed and position of the wheel. Next, you should take a good look at the content of the DC motor braking method (the original article here is a link ). In other cases, a small Micromethod capacitor is used to connect the two ends of the motor to prolong the service life of the motor. This is really good for motors with noise and low prices. It is almost twice the life of the motor. However, the use of this technology has little improvement on expensive high-end motors.
Differences between a brush motor and a brushless motor
Brushless motors have higher efficiency.
Brushless motors have low electrical noise.
Brushless motor continues to work longer
Brushless motor is expensive
Brushless motors require dedicated Controllers
Voltage
Generally, it ranges from 5 to 12 V, but the motor can reach a very large range for specific purposes.
Higher Voltage means greater torque, but greater power is needed
Motor can be used at or below rated voltage (other design requirements shall be met)
Maximum rated voltage Aging RateCurrent
When purchasing a motor, consider the stop current and running current (maximum and minimum)
Stop current: Current when the motor is powered by resistance and cannot run
Running current: Current when the motor is at zero torque
It is best to measure the current curve related to the voltage, current and required torque for optimization.
When the load torque of the motor changes, such as the motor reversal, it is expected to withstand short-term peak current
The current peak can reach twice the hold current. If there is no protection device, the control circuit will be damaged.
Use diodes to prevent reverse current from damaging your circuit
Check the rated power of your circuit and use a heat sink if neededPower (that is, voltage multiplied by current)
Motor Running is often close to the stop current, or the reverse current under high torque, may cause the motor to burn out
If it cannot be avoided, the motor torque with heat dissipation device can be used.
When purchasing a motor, consider the stall and working torque (maximum and minimum)
Hold torque-torque when the power is insufficient to maintain motor Rotation
Working torque-motor torque when the motor's Yin torque is zero
Changing the voltage will change the torque.Speed
The motor runs at the maximum possible speed with the highest Aging Rate
Adjusting the motor can make the motor turn faster, and it can get a slower output speed and a larger torque.
Remember that the torque determines the acceleration, So robots with poor acceleration are actually low-speed robots.
If you are not sure, you can consider that the torque takes precedence over the speed.Efficiency
Maximum rated voltage Aging Rate
The motor runs at the highest possible speed with the highest Aging Rate
Use gear (optional, purchase a motor with built-in gear or gear outside)Control Method
The brushless motor works through induction and must use a dedicated controller.
There are many different types of brushless DC motors that can operate at 2 or 4 pole
Decoder-a device that can count the rotation speed of a wheel or an electrical rack and measure the rotation speed of a feedback loop
Tachometer-device for measuring motor current changes to control output torque-linear motor Source: http://www.societyofrobots.com/(This part of content will be further modified) Bit by bit records of Linear Motors * linear motors like X-Y planar Asynchronous Motors
* The magnetic field at the end of the motor plane is difficult to predict but must be solved
* There are many types of Linear Motors: Sound ring motors, Brushless AC servo motors, stepper motors and their variants
* The slot force of the brushless Iron Core Linear Motor must be smaller than 2% or more.
* The Three-Phase Motor requires little fluctuation in force
* The thrust-movement mass ratio determines the bearing capacity of the linear motor.
The smaller the mobile quality, the larger the load capacity. In addition, due to the force generated by moving the mass at a large acceleration and reduction speed, the machine will produce great vibration. For some reason, a good linear motor should keep the moving quality as small as possible during operation.
* Consider moving the two axes simultaneously or independently.
* The operation cycle must be kept low to avoid overheating.
* When a good linear motor works, the length of the mobile cable must be as short as possible and the service life must be long.
* Other Factors to consider: effective travel, resolution, plus payload, moving quality, accuracy, repetition precision, straightness/flatness, maximum speed, minimum acceleration, Coil Inductance, and Other voltages* Depends on the linear motor type
* The higher the voltage, the larger the torque, but more power is needed.
* The motor can work above or below the rated voltage (suitable for other design requirements)
* Maximum operating efficiency current at rated voltage
* When buying a motor, you must consider the stop and current (maximum and minimum)
* Stop turn current-current that fails to run when the power supply is connected
* Working current-current when the Resistance Torque of the motor is zero
* It is best to determine the relationship curve with voltage, current and required torque for optimization.
* A transient peak current is expected when the motor torque changes (such as the motor reversal ).
* Current peak-up to 2 times of stop current, if not protected, the control circuit will be damaged. * use a diode to protect your circuit against reverse current damage. * Check the rated power of your circuit. If necessary, use a heat sink.
Power (voltage x current) * often enables the motor to work when the current is close to the current, or often reverse under a large torque, will melt the motor * If unavoidable, use the torque of the motor cooling slot * When purchasing the motor, consider the stop torque and working torque (maximum and minimum)
* Stop torque-when the power is switched on, the motor does not generate enough torque to rotate.
* Working torque-the torque of the motor when the Resistance Torque is zero
* Voltage changes will change the torque speed * the motor operates at the highest speed with maximum efficiency
* The drive on the motor can make the motor turn faster, but the lower the output speed, the larger the torque
* Remember that the torque determines the acceleration. Therefore, a high-speed robot with poor acceleration performance is actually a low-speed robot.
* If you are not sure, the torque rather than the speed efficiency will be given priority * the most effective rate at the rated voltage
* The motor has the highest efficiency when working at the maximum speed
* Friction is related to low speed motion.
* The method for controlling the use of the drive device (optional, a motor with built-in gears or gears outside) * depends on the motor type
* Most Linear Motors provide dedicated controllers at the same time. What is a servo motor?
A servo motor is also called an executive motor. In an automatic control system, it is used as an execution component to convert the received electrical signal into an angle displacement or angular velocity output on the motor shaft. It is divided into two categories: DC and AC servo motors. Its main feature is that when the signal voltage is zero and there is no rotation, the rotation speed decreases at a constant speed with the increase of torque.
Servo motor current
In addition to the feedback control system that is hard to predict and solve now, the servo motor current works like a DC motor. If your DC motor is not at the specified angle, it will soon generate a large amount of current to reach this angle. In addition, there are other performances. If an experiment is performed with an angle unchanged from the swing arm of the servo motor and precise loads are mounted, the measured current will not be what you expect. You will think that the current will increase linearly as the weight increases. However, what you will get is unpredictable curves and rate.
All in all, the current of the servo motor is particularly unpredictable.Stop torque, stop current, loss current
Because the servo motor contains a DC motor, please refer to my DC motor guide to learn about the stop-to-Stop characteristics of the servo motor
