Robust Control Matlab

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Thread Starter

Anwesha Chatterjee

Hello all,

I am new to this forum, so would like to start with a brief introduction. I am a 4th year Engineering student, and am majoring in Control systems.

Currently i am attempting to control a flexure based feed unit using MATLAB and SIMULINK. A mechanical model has been created on simulink. The method i have employed is forming a linearised model, attempting control of this linear model using LQR and Hinfinity, followed by implementation of this controller on the experimental setup (using DSpace).

Currently i have successfully formed the LQR control and Hinfinity control for the mechanical model on simulink. however there is a problem when i include saturation (an integral part of the loop. since the real system would not be able to go beyond 120 um in displacement). LQR works fine, but Hinfinity , which was initially stabilising to the required end positions, is not stable anymore!!!! what might be causing the problem

here are some more details:

It is a 2 input 2 output system
the command used is <hinfsyn>, uncertainty is modeled accurately
system fully observable and controllable

any info will be helpful, and let me know if there is any additional information i could provide.

Anwesha :)
 
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