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I have tried to compare two courses, and there seems to be some overlap, but not as much. Which method is better when controlling a nonlinear system? Also, what is the main difference between the two?

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  • $\begingroup$ In case the nonlinear control course features Lyapunov stability and you haven't been taught that yet, you might consider that one. Lyapunov stability is probably one of the most important concepts of control theory. $\endgroup$ – OpticalResonator Dec 31 '19 at 20:16
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    $\begingroup$ This looks like an academic guidance question. Such questions often involve personal choice and can probably be better answered by an adviser or counselor. We do not believe this site's format is well-suited to such questions, which are therefore considered off-topic. $\endgroup$ – Wasabi Oct 22 '20 at 17:42
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In nonlinear control theory, you will recognize most concepts such as controllability and observability where the linear case is often a special case of the nonlinear case. I would highly recommend digging into linear control theory first if you have not done so. Depending on the course you take, concepts such as Lyapunov stability are discussed here, which is a very important concept.

In contrast, optimal control is rather independent of the underlying system, be it linear or nonlinear and has therefore overlap with both, depending on what type of optimal control problem you look at. I would say that it has a broader scope since you will find optimization problems everywhere in different fields of research. Especially important is model predictive control which solves optimal control problems on a receding horizon and is one of the most-used control schemes in the industry (apart from PID control) because it can handle state and input constraints explicitly (which most other types of control fail to achieve).

All in all, I would recommend going this path:

Linear control theory => Nonlinear control theory => Optimal control theory

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    $\begingroup$ I agree with the answer, although it is worth weighing the options in the context of the intended application of the controls algorithms the OP needs to address, since controls is a mature and therefore vast field. For instance, MIMO, robust control and Kalman filtering are generally taught as a part of the linear control theory, some of which may be beyond the scope of what is required by the applications of interest. $\endgroup$ – kbakshi314 Mar 18 at 13:40
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In control systems, the main focus is the design of a controller for machines or robots, here we mainly deal with linear systems application of linear control theory. While non-linear systems is an advanced topic, where we deal with advance and mathematically more complex systems.

If its ur first course in control systems or automatic control. Go for the linear control system, but if you have a basic background of controls then you can go for non-linear control.

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    $\begingroup$ If it’s a first course, I’d recommend classical control systems then optimal controls. $\endgroup$ – Eric S Dec 31 '19 at 14:52
  • $\begingroup$ ya, I certainly agree on that. What I meant was that it depends on how much knowledge of the basics of controls he has already. Non-linear control can be a harder subject, so until one is confident enough in his/her skill, there wouldn't be much help by taking a harder subject earlier. $\endgroup$ – anshul suri Jan 4 '20 at 11:45

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