For a control system, How to design a controller using op-amp to eleminate the error for step & ramp inputs?

From experience, it's easier to use lead and lag dynamic compensators than pure differential and integrating amplifiers. You should be able to find the circuits on the web or in a good book on control.





If you do choose to go with a PID circuit, be aware that the classical circuits for one of the amplifiers (think its the differentiator, but it was a few years ago!) isn't very stable. The solution is to put a capacitor (I think) across one of the resistors - this solution came from 'The art of electronics', which has most, if not all, of the circuit diagrams and info in it that you'll need in any case!For a control system, How to design a controller using op-amp to eleminate the error for step %26amp; ramp inputs?
For zero steady state error with a step or ramp input, you can use some type of integration of the error. In a PID controller, this is the ';I'; or Integral gain part. There are many examples on the internet of PID controllers using op-amps. The integral part will involve a capacitor that will continue to charge as long as there is any error, forcing the output stronger and stronger until it matches the desired output. You will want some dampening (the Derivative part of a PID controller) because integral control tends to be oscillatory and can be unstable.