Oversampling in PID tuning

I'm developing a PID controller to control the position of a laser beam. The controller will be implemented in software on a TI micro controller. The sampling time will be 15 us but I need to simulate the system at a higher frequency to check for higher frequency oscillations. What would be the best way to do it?

[Muthu Annamalai]

Hello Wolfy

As Azizz has pointed out, it will be helpful if you specify what you are looking for here.

Do you want guidance on a Simulink model or MATLAB code. Does the MATLAB code have to generate C-code so you may put it one a microcontroller.

Better clarifications will help you get a prompt answer.

Answer 1

[Azzi Abdelmalek]

1. The best way to do what?
2. Your PID is continue or discrete?
3. How about the system you are controlling?

[Wolfy]

1. Tune the PID for the correct sampling rate for the implementation but then simulating it at a higher sampling rate.

2. The PID is going to be implemented in software, so it's discrete.

3. The system is a laser beam pointing to a MEMS mirror controlled via DAC. The position of the beam is tracked by a Position Sensitive Device (PSD), whose signal is sent back to the micro-controller via ADC.

[Azzi Abdelmalek]

Wolfy, Even a continuous PID can be implemented with software, at a high frequency. However, for discrete PID, the frequency can't be chosen as high as you want, because it will cause the instability of your closed loop. The sample time depends on the system you want to control.