Views: 4 Author: Site Editor Publish Time: 2022-08-17 Origin: Site
Control modes of a servo motor
A motion controller usually use two types of commands to control servo motors: digital pulse and analogue signal.
1. Digital pulse
In this method that is similar to the control mode of stepper motor, the motion controller sends “pulse/direction” or “CW/CCW” type pulse command signal to the servo motor driver, which works in the position control mode and completes the position closed loop. This control model is adopted by most of Japanese and domestic servo motor products.
Pros: easy to debug the servo motor system; not easy to produce interference.
Cons: low servo system response.
2. Analog signal
In this control mode, the motion control system sends +/-10V analog voltage commands to the servo driver, and receives position feedback signals from position detection elements such as motor encoders or linear encoders. Most of the servo products in Europe and America adopt this mode of operation.
Pros: fast servo response.
Cons: more sensitive to field interference; slightly complicated debugging.
Since you have known the above two control modes of the servo motor, Leili Motor will next describe six steps to debug the servo motor by analog signal.
6 Debugging steps
1. Parameter initialization
Initialize the parameters before wiring.
On the controller: Choose the control mode, reset the PID parameter, set off the enable signal when the controller is energized as default, store this condition and ensure that when the controller is energized the next time, this condition is as default.
On the servo motor: Set the control mode, set to enable controlling from outside, gear ratio output by encoder signal, set the proportional relation between control signal and motor speed. Generally, it is suggested that the maximum design speed in servo operating should correspond to 9V control voltage.
2. Wire connection
Shut down the controller and connect the signal wire between the controller and servo motor. The following wires must be connected: the analogue output wire of the controller, enabling signal wire, and encoder signal wire output by the servo motor. After the wire connection is rechecked and there is nothing wrong, energize the servo motor and the controller (including PC).
And then the servo motor should have no motion and can rotate easily by external force. If not, check the setting of enabling signal and wire connection. External force should be used to rotate the servo motor to check if the controller can detect the motor position change. If not, check wire connection and setting of encoder signal.
3. Direction testing
For one closed loop control system, if the direction of feedback signal is incorrect, the consequences must be disastrous.
Turn on the enable signal of the servo motor attachments via the controller, and the servo motor should rotate at a lower speed, which is called “zero drift”, whose command or parameter will be displayed on the controller. The command or parameter can help you to confirm whether the speed and direction of the servo motor can be controlled by the command or parameter.
4. Zero drift inhabitation
During the closed loop control, the existence of zero drift will have certain influence on the control effect and you’d better restrain it. Adjust carefully using the parameters of zero drift inhabitation on the controller or the servo motor to make the motor speed close to zero.
5. Closed-loop control building
Turn on the servo enable signal again by the controller and input a smaller ratio gain on the controller. Turn on the enable signal of the controller and servo motor.
6. Closed loop parameter adjustment
Adjust the control parameters finely to ensure that the servo motor moves in accordance with the command from the controller.
