Assignment:
Consider the block diagram, describing a process under Proportional-Integral-Derivative control.
1) Is the system open loop stable? Justify your answer
2) Let Ki = 10. Use the Routh-Hurwitz criterion to find the range of Kd, and Kp in terms of Kd, so that closed loop stability is achieved.
3) Suppose that Ki = 10, Kd = 1, and Kp = 15. A Bode plot of the open loop transfer function with these parameter values is shown in the attachment. Sketch a Nyquist plot for this system and use this sketch to determine if the system is closed loop stable.
