ADLINK PCI-8258 - Manual (Page 98)

84 Motion Control Theory
4.2.3 Manual Servo Tuning
Manual fine tuning is still necessary for satisfying different needs.
You may change three controller parameters manually:
Proportional gain, KP, Integral gain, KI and Derivative gain, KD.
You may change velocity or acceleration feedforward gain as
required. The manual fine tuning procedure can be executed in
the PID setup page of signal sampling function in
MotionCreatorPro 2. The manual fine tuning procedure can be
executed in steps described below:
Step 1:
Set up KI to zero and KP and KD with initial values, e.g. set value
of KP to 1 and KD to 100. Start motor motion, adjust KD to greater
value and observe the error position signal, in case of vibration
decrease KD value until vibration situation disappears.
Step 2:
Increase KP value gradually to bring down the position error
signal. Similarly vibration situation may appear when KP value is
getting too high. If this happens, bring down the KP value until
vibration situation disappears. You may encounter the overshoot
phenomenon. Increase KD value until overshoot situation
disappears then you can increase KP value. In general, for
actuator in torque control mode the KP value is one fourth of that
of the KD one.
Step 3:
Before adjusting KI value, please note watch carefully the integral
limit settings as this will affect the effect of integral control.
Increase KI value gradually to being down the ready state error to
zero step by step. When there is vibration encountered, decrease
KI value until there is no vibration any more.
Step 4:
Eventually you may increase velocity /acceleration feedforward
gain step by step to higher up response speed furthermore.
Please note that this may lead to overshoot phenomenon. After
manual final tuning you may use filters to improve high frequency
noise encountered when turning off the motor. For design and use
of filter, please refer to Section 4.2.4.