PI vs PD for position, speed, force, current control
PI vs PD for position, speed, force, current control
(OP)
Dear all,
I have a question regarding using PI or PD control based on the control variable. Is there a relation? As I found a lot of people use PI controller for speed or current control for servo systems. However, PD is used a lot for position or force control. I am wondering if there are reasons for that or recommendations for the type of the control based on the control variable and the application.
I have a question regarding using PI or PD control based on the control variable. Is there a relation? As I found a lot of people use PI controller for speed or current control for servo systems. However, PD is used a lot for position or force control. I am wondering if there are reasons for that or recommendations for the type of the control based on the control variable and the application.
RE: PI vs PD for position, speed, force, current control
If there is only a single integration in the plant under control -- for instance torque/force to velocity, or voltage command to current thru an inductive load -- you do not need derivative action. The system is much more inherently stable.
Curt Wilson
Omron Delta Tau
RE: PI vs PD for position, speed, force, current control
Regards,
RE: PI vs PD for position, speed, force, current control
RE: PI vs PD for position, speed, force, current control
If there is a double integration in the plant under control -- for instance, from a torque/force command thru velocity to position -- you need derivative action to get the damping required for stability. Proportional gain here is just a spring (no shock absorber -- the car suspension analogy is a good one here).
If there is only a single integration in the plant under control -- for instance torque/force to velocity, or voltage command to current thru an inductive load -- you do not need derivative action. The system is much more inherently stable.
I am wondering about guidance for when each type is used
RE: PI vs PD for position, speed, force, current control