The Three Control Mode of Servo Motor

　　1. Pulse control mode

　　For small machines, it is common to use a pulse to control the position of the motor. This control method is very simple and easy to understand. The basic control method: the number of the pulse determines the motor pulse, the frequency of pulse determines the motor speed.

　　First, the driver receives two high-speed pulses, by the phase difference of the two pulses, the rotation direction of the motor can be determined. As the picture shows, if B is 90 degrees faster than A, it is positive rotation; if B is 90 degrees lower than A, it is negative rotation. At the process of running, the controlled two-phase pulse is alternating, then this method is differential control. This control method has higher immunity from interference. However, this mode makes the motor shaft use two high-speed pulse port.

　　Second, The driver receives two high-speed pulses, but the two high-speed pulse does not coexist. When one is in the output state, the other must be in an invalid state. In the two high-speed pulses, one output is a positive direction, and the other is in a negative direction. This method makes the motor shaft use two high-speed pulse port.

　　Third, only one pulse signal should be given to the driver, the positive and negative operation of the motor is determined by the IO signal in one direction. This control method is very easy to control, the high-speed pulse port also occupies the least amount of the resources.

　　2. Modulating control mode

　　In the application where a servo motor is needed to realize speed control, we can use analog quantity to realize the speed control. The value of the analog quantity determines the operation speed of the motor. The analog quantity has two methods to choose from, current or voltage. The voltage mode: it is only necessary to add a certain voltage at the control signal end. It is very easy to realize. However, using voltage as a control signal, in the complex scenes, the voltage is easy to interfere with. The current mode: the corresponding current output module is required. But the immunity from interference is very strong can it can be used in complex scenes.

　　3. Communication control mode

　　The common method used by servo motor has CAN、EtherCAT、Modbus、Profibus. It is a preferred control mode in some complicated and big system scenarios. The size of the system and the number of the motor shaft are easy to cut without complex control wiring.

　　The speed control and torque control of the servo motor are controlled by analog quantity. The position control is realized by sending a pulse. If you have no need for the speed, the position of the motor, you can use torque mode.

　　If you have a certain requirement on the position speed, not the torque, you can use speed or position mode. If the upper controller has a better closed-loop control function, the speed control effect will be better.

　　In terms of response speed, torque mode has the least amount of computation, the driver has a fast response to the control signal. The position mode has the largest amount of computation, the driver has a slow response to the control signal.

　　If there is a high demand for dynamic performance in the motion, it is necessary to adjust the motor in time. If the computation speed of the controller is slow, you can use position mode to control. If the computation speed of the controller is relatively fast, you can use speed mode. If there is a better upper controller, you can use torque mode to control.