I've got a system where the PID controller tries to control the torque of a motor to match the setpoint value. The output of this system is show below.
As you can see the Torque is being controlled very rough to maintain speed (that's because the input varies very rough). The thing what I want to do is to let the controller control the system tot the setpoint value +- an error, so that the torque will be a lot smoother controlled. I was thinking about a filter after the PID controller to filter the high frequency component of the controller, but than the controller still would try to reach the only setpoint value that is set without the error that is permisseble.
The ultimate solution is using a interval as a setpoint for the PID controller