A robust parameter adaptive law for model ference adaptive control systems

For the improvement of robustness of Model Reference Adaptive Control Systems(MRACS), this paper presents a new adaptive law which can be related to the consideration of control cost in MRACS. The new law is different from the ??-modification of Ioannou and-Kokotovic[2,3]. But by use of their skill, we have shown that the new adaptive law is with good robustness property with respect to parastics and bounded disturbances. We have also given the attracting set and the residual set. Under some conditions the convergence rate is shown to be exponential.