Several steps for servo motor debugging
1 digital pulse
This method is similar to the control method of a stepper motor, where the motion controller sends a "pulse/direction" or "CW/CCW" type pulse command signal to the servo driver; The servo driver works in position control mode, and the position closed-loop is completed by the servo driver.
2 Analog signals
In this way, the motion control system sends+/-10V analog voltage commands to the servo driver and receives position feedback signals from position detection components such as motor encoders or linear gratings; The servo driver operates in speed control mode, and the position closed-loop is completed by the motion controller.
The general debugging steps for the motion controller to control the servo motor with analog signals are as follows:
Before wiring, initialize the parameters first. On the control card: select the control method and reset the PID parameters to zero, so that the default enable signal is turned off when the control card is powered on. Save this state to ensure that it is in this state when the control card is powered on again; On the servo motor: Set the control mode, enable external control, output the gear ratio of the encoder signal, and set the ratio relationship between the control signal and the motor speed. Generally, it is recommended to use a control voltage of 9V corresponding to the larger design speed in servo operation.
2 Wiring
Power off the control card and connect the signal wire between the control card and the servo. The following lines must be connected: the analog output line of the control card, the enable signal line, and the encoder signal line output by the servo motor. After rechecking the wiring and ensuring there are no errors, the servo motor and control card should be powered on. At this time, the motor should not move and can be easily rotated with external force. If this is not the case, check the setting and wiring of the enable signal, rotate the motor with external force, and check whether the control card can correctly detect changes in the position of the motor. Otherwise, check the wiring and setting of the encoder signal.
3 Test directions
For a closed-loop control system, if the direction of the feedback signal is not correct, the consequences will definitely be catastrophic. By turning on the Fuji servo motor enable signal through the control card, the servo should rotate at a lower speed, which is the legendary zero drift. Generally, the control card will have instructions and parameters to suppress zero drift. Use this command or parameter, Check if the speed and direction of the servo motor can be controlled through this command (parameter). If it cannot be controlled, check the parameter settings of the analog wiring and control method; Confirm to give a positive number, servo motor forward rotation, encoder count increase, give a negative number, motor reverse rotation, encoder count decrease. If the motor is under load and has limited travel, do not use this method. Do not give excessive voltage for testing, it is recommended to be below 1V. If the direction is inconsistent, modify the parameters on the control card or servo motor to make them consistent.
4 Suppress zero drift
In the closed-loop servo control process, the presence of zero drift will have a certain impact on the control effect. It is better to suppress it. Use the control card or servo to suppress zero drift parameters, carefully adjust them, and use the motor speed and zero. Due to the randomness of zero drift itself, it is not necessary to require the servo motor speed to be absolutely zero.
5. Establish closed-loop servo control
Once again, release the enable signal of the servo motor through the control card and input a small proportional gain on the control card. As for how large the gain is, it can only be considered small based on feelings. If you are really unsure, enter the smaller value allowed by the control card and turn on the enable signal of the control card and servo motor. At this point, the phone should be able to roughly follow the motion instructions.
6. Adjust closed-loop parameters
Fine tuning of control parameters to ensure that the servo motor moves according to the instructions of the control card is a necessary task, and this part of the work is more about experience.
