Robust Adaptive Control of Uncertain Nonlinear Systems With Time-Varying Input Delay

Author(s):  
W. X. Deng ◽  
J. Y. Yao

In this paper, a robust adaptive controller is proposed for a class of uncertain nonlinear systems subject to time-varying input delay, parametric uncertainties and additive bounded disturbances. The desired trajectory based adaptive feedforward technique and a predictor-like robust delay compensating term are integrated via backstepping in the controller design. The proposed controller theoretically ensures semi-global uniformly ultimately bounded tracking performance based on Lyapunov stability analysis by employing Lyapunov-Krasovskii (LK) functionals. Simulation results are obtained to illustrate the effectiveness of the proposed control strategy.

Author(s):  
James P. Nelson ◽  
Mark J. Balas ◽  
Richard S. Erwin

Many systems must operate in the presence of delays both internal to the system and in its inputs and outputs. In this paper we present a robustness result for mildly nonlinear systems. We use this result to show that, for small unknown time varying input delays, a simple adaptive controller can produce output regulation to a neighborhood with radius dependent upon the size of an upper bound on the delay. This regulation occurs in the presence of persistent disturbances and the convergence is exponential. We conclude with an example to illustrate the behavior of this adaptive control law.


Automatica ◽  
2017 ◽  
Vol 76 ◽  
pp. 222-229 ◽  
Author(s):  
Serhat Obuz ◽  
Justin R. Klotz ◽  
Rushikesh Kamalapurkar ◽  
Warren Dixon

2014 ◽  
Vol 568-570 ◽  
pp. 1108-1112
Author(s):  
Ning Liu ◽  
Yu Sheng Liu ◽  
Qiang Yang

This paper proposes a robust adaptive robust controller for nonlinear systems represented by input-output models with unmodeled dynamics. Under the circumstances that the output of the system is bounded, the proposed controller can guarantee that all the variables of the system are bounded in the presence of unmodeled dynamics and time-varying disturbances. The scheme does not need to generate an additional dynamic signal to dominate the effects of the unmodeled dynamics. It is shown that the mean-square tracking error can be made arbitrarily small by choosing some design parameters appropriately.


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