Madam Shweta,

A possible way could be by using sliding mode control or by using compensation techniques that would nullify the effect of the zeros when the axis of operation is shifted~ Srikanth

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http://ieeexplore.ieee.org/document/7085073/

Dear Shweta Balajiwale,

In loop analysis we can describes how stability and robustness can be determined by investigating how sinusoidal signals propagate around the feedback loop. The Nyquist stability theorem is a key result which gives a new way to analyze stability. It also makes it possible to introduce measures degrees of stability. Another important idea, due to Bode, makes it possible to separate linear dynamical systems into two classes, minimum phase systems that are easy to control and non-minimum phase systems that are difficult to control.

I suggest to you attached files in topics, i hope that you can find adapted solution for your problem.

Best regards

It is very hard to require among several zeros every zero be LHP. Therefore most of systems are non-minimum phase, and this proposed question is very important.

From root locus rules, the most obvious harm of RHL zeros is that high gain is prohibited, because high gain can make the closed poles reach these zeros.

This is why the asymptotic LTR of state space theory cannot be applied to non-minimum phase systems, because asymptotic LTR means asymptotic high gains.

However, using a simple state space technique described in my publications, an output feedback compensator (OFC) can be designed for systems either with more outputs than inputs or with at least one LHP zeros (the OFC poles will be assigned to match these LHP zeros).

This OFC is very general because it is equally very hard to have among several zeros every zero be RHP.

This OFC can estimate a number of linear transformations of system state (like a number of additional system outputs), while this number equals the OFC order. Thus a much improved static output feedback control can be designed. This form of control is a constrained state feedback control, which is by far the best form of feedback control.

This OFC has a distinct advantage than normal observers. The exact LTR or full realization of robustness of state feedback control, is achieved by OFC.

This OFC fully utilizes the LHP zeros by matching them with the OFC poles, while avoiding the harms of RHP zeros by not requiring high gains at all.

Thank you so much everyone for the suggestions. If I have further doubts on this topic,  I will post here.

You may try Robust-PID, MPC, or smith predictor control.