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A new adaptive law for robust adaptation without persistent excitation. (English) Zbl 0617.93035
Robust adaptive control for plants with unknown parameters has invariably proceeded along two lines. One of them relies on the persistent excitation at certain relevant signals in the adaptive loop. The other one is concerned with the modification of the adaptive law in such a manner that the overall system has bounded solutions in the presence of bounded perturbations. This paper supplies a blend of the above two approaches for improving the robustness of adaptive systems. The proposed scheme modifies the $$\sigma$$-modification used for robustness by replacing $$\sigma$$ by a term proportional to the output error. The performance of the scheme is improved in all respects while retaining the advantage of assuring robustness in the presence of bounded disturbances.
Reviewer: M.de la Sen

##### MSC:
 93C40 Adaptive control/observation systems 93B35 Sensitivity (robustness) 93C10 Nonlinear systems in control theory
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