I am trying to add a PID controller to the elec_motor_dc_pwm.slx DC motor Simscape example:
However, Simscape complains about an algebraic loop in the feedback path.
This answer says models shouldn't contain both "physical signal to simulink" and "simulink to physical signal" converter blocks. (My picture does.) But then how do you design a feedback controller? This Simscape help page suggests replacing the "PS-to-S" blocks with blocks like "PS Subtract" and "PS Gain". However, there is not a "PS Derivative" block, which would be needed for a PID controller.
Thanks for your help.