Tuning rules for position and velocity controllers in PPI and PIPI electrical servomechanisms are developed using the root locus
design method. PPI controller is equivalent to PID controller with a setpoint filter. PIPI servo provides zero steadystate error for linear
disturbances, which may be important for some tracking tasks. Three design data are needed to calculate the tunings, i.e. drive gain, settling
time and control cycle. The development begins with continuous controllers for better understanding. Closedloop transfer functions involve
real multiple poles, so the responses are smooth, without overshoot. Upper limits on control cycles as fractions of settling times are given.
Some experimental results are presented.
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