Velocity and Position Control Using NI PID

[Sunnyabc]

Hi

I am using the NI PID Advanced Control Block set to control the position and the velocity of a rotating machinery.  This machine is supposed to operate in cyclic motion between +100 deg and -100 deg with constant velocity.  I am using a triangular wave signal as a setpoint whose peak value is 100 and the frequency corresponds to the desired speed.  The issue is that I find it very hard to achieve both position and velocity control in the same time.  Can someone give me some suggestions?  I would most appreciate it.  Right now, I can only use the PID controller.  Thanks.

[Z'atari]

Are you trying to do a position and velocity control with the same PID parameters?

Also, can you give us more information on the setup?

[Sunnyabc]

Yes.  I am trying to control the position and velocity using the same PID parameters.  The equipment that I am trying to control is very much like a flywheel. I have an encoder to measure the position. The control loop that I am using is basically a position control system.  Since the setpoint is the trianular wave, I thought that it should give me a constant speed. Position control accuracy is acceptable, but it is very difficult to get constant speed. I may try to include an inner velocity control loop. But I do not have a speed sensor. I can estimate the speed from position measurements, but it is very nosiy.