Control Systems

How many capacitors would be required to build an op-amp based electronic circuit that functioned as a PID compensator?

2. 1 for PI 1 for PD

If you needed to reduce the bandwith of a system what sort of compensator would you use and why?

Phase-lag because it decreases the gain at higher frequencies

What affect will a lead compensator have on the time domain response of a system and why?

fast transient response

What compensator design methodology is best suited when a system has significant time delay and why?

Phase-lag because it is less susceptible to noise due to the decreased bandwidth, since a delay will increase the effects of noise this cancels it out

What is the frequency domain design procedure for a phase-lag compensator?

1. Set compensator gain for steady state specs 2. Create Bode plot 3. Find frequency where phase margin is 5-10 deg above target 4. Place 0 at least 1 dec before (3) 5. Place pole so magnitude reduction at (3) is as needed 6. Calculate controller gain to satisfy steady state error

What is the frequency domain design procedure for a phase-lead compensator?

1. Create Bode plot 2. Set gain so that 0dB point is half desired value 3. Create compensated Bode plot 4. Calculate required gain margin 5. Calculate additional phase margin needed 6. Calculate beta 7. Calculate T

When designing a controller for a high order system which design method would be more accurate and why?

Routh Hurwitz works for all orders to determine stability without needing to factorise (useful at high orders). Higher order systems can have both temporal performance and steady state error improved by a PID controller