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Vol: 51(65) No: 2 / June 2006         Smooth Switching Function with Adaptive Gain in Sliding Mode Observer-Controller to Robotic Manipulators Control Adrian Filipescu Department of Automation and Industrial Informatics, "Dunarea de Jos" University of Galati, Faculty of Computer Science, Domneasca no.47, 800008,Galati, Romania, e-mail: Adrian.Filipescu@ugal.ro Andrei Cosor Department of Automation and Industrial Informatics, "Dunarea de Jos" University of Galati, Faculty of Computer Science, Domneasca no.47, 800008,Galati, Romania, e-mail: Andrei2105@yahoo.com Keywords: sliding observer-controller, smooth switching function, robotic manipulator, adaptive gain. Abstract Closed loop estimation scheme for time-varying parameters is proposed in order to obtain useful information despite loads, external disturbances and faults detection. An adaptive gain smooth sliding controller, based on a smooth sliding observer, is developed to control nonlinear systems with uncertain parameters and state functions. In order to alleviate chattering, smooth switching function, instead of pure relay one, is used into the observer and the controller. The gain of the switching functions is adaptively updated, depending on the estimation error and tracking error, respectively. Using adaptive gains, the response is smoother and tracking performances are improved. Simulation results with a SISO robot with flexible joint and a MIMO robotic manipulator with two degree of freedom (2-DOF) are presented to show the interest of the approach. References [1] C. Canudas de Wit, and J. J. Slotine, “Sliding observers for robots manipulators”, Automatica, Vol. 27, No. 5, pp. 859-864, 1991. [2] A. Filipescu, L. Dugard and S. Stamatescu, “Robots control based on parameter identification and adaptive gain smooth sliding observer-controller,” in CD Preprints 16th IFAC World Congress, Prague, 2005. [3] H. K .Khalil, Nonlinear Systems. Prentice-Hall, Englewood Cliffs, NJ, 1996. [4] R. Marino and P. Tomei, Non-linear Control Design, Prentice-Hall, Englewood Cliffs, NJ, 1995. [5] R. Sanchis and H. Nijmeijer, “Sliding Controller-Sliding Observer Design for Non-linear Systems”, European Journal of Control, Vol. 4, pp. 208-234, 1998. [6] J. J. Slotine and S. S. Sastry, “Tracking control of non-linear systems using sliding surfaces, with applications to robot manipulator”, Int. J. Control, Vol. 38, No. 2, pp. 465-492, 1983. [7] V. I. Utkin, Sliding Modes in Control and Optimisation, Springer Verlag, Berlin, 1992. [8] J. X. Xu and H. Hashimoto, “Parameter identification methodology based on variable structure control”, Int. J. Control, Vol. 57, No. 5, pp. 1207-1220, 1993. [9] J. X. Xu and H. Hashimoto, “VSS theory-based parameter identification scheme for MIMO systems”, Automatica, Vol. 32, No. 2, pp. 279-284, 1996. [10] J. X. Xu, Y. J. Pan and T. H. Lee, “A VSS identification scheme for time-varying parameters”, Automatica, Vol. 39, No. 2, 5, 724-734., 2003.