Journal of Intelligent and Robotic Systems 17: 371-386, 1996. 371 @ 1996 Kluwer Academic Publishers. Printed in the Netherlands. A Robust Adaptive Sliding-Mode Control for Rigid Robotic Manipulators with Arbitrary Bounded Input Disturbances MAN ZHIHONG and D. HABIBI Department of Computer and Communication Engineering, Edith Cowan University, W.A. 6027, Australia (Received: 8 November 1994; in final form: 5 March 1996) Abstract. In this paper, a robust adaptive sliding-modecontrol scheme for rigid robotic manipu- lators with arbitrary bounded input disturbances is proposed. It is shown that the prior knowledge on the upper bound of the norm of the input disturbance vector is not required in the sliding-mode controller design. An adaptivemechanismis introducedto estimatethe upper bound of the norm of the input disturbance vector. The estimate is then used as a controllergain parameter to guarantee that the output tracking error asymptotically converges to zero and strong robustness with respect to bounded input disturbances can be obtained. A simulationexample is given in support of the proposed control scheme. Key words: sliding-modecontrol, adaptive mechanism,rigid robotic manipulator. 1. Introduction In robot control engineering, the issue of designing robust adaptive controllers to eliminate effects of uncertain dynamics and arbitrary bounded input disturbances is one of the challenging topics. Most of robust adaptive control schemes in [ 13- 17] and [23] consider rigid robotic manipulators with only uncertain dynamics, and asymptotic stability has not been proven to be uniform in these schemes [ 17] and small changes in dynamics may result in loss of stability. Further, if the controlled robotic systems have both large system uncertainties and arbitrary bounded input disturbances, these adaptive control schemes are inadequate to achieve satisfactory performance. In recent years, sliding-mode technique has provided an efficient method for the control of robotic manipulators with large uncertainties and bounded input disturbances. The work in [5, 8-11 ] have shown that robustness and convergence can be established for robotic manipulators with large system uncertainties and bounded input disturbances by using the sliding-control theory based on the upper and the lower bounds of unknown system parameters and the upper bounds of the input disturbances. The problem of using the above method to design the sliding- mode controllers is that, although the upper and the lower bounds of unknown parameters can be obtained by experiments according to structural properties