國立臺灣師範大學機電工程學系Lu, Yu-ShengHwang, Chi-Sheng2014-10-302014-10-302009-09-010253-3839http://rportal.lib.ntnu.edu.tw/handle/20.500.12235/37054This paper describes the design of a high-order variable-structure disturbance estimator (VSDE) that provides asymptotic estimation of unknown disturbances described by polynomial functions of time with arbitrary degrees. In comparison with conventional VSDEs, the high-order VSDE requires only a small switching gain for ensuring the existence of a sliding mode, thus alleviating the chattering phenomenon. Moreover, the transfer function of a high-order VSDE from an unknown disturbance to its estimate can have a high relative degree to enable the estimation of time derivatives of an unknown disturbance while providing adequate high-frequency attenuation. Two high-order VSDEs were implemented to simultaneously observe the motor-side and the load-side disturbances in a harmonic drive system. Experimental results show that the compensation offered by the high-order VSDEs effectively deals with the disturbances induced by harmonic drive gearing.disturbance estimatorvariable-structure systemssliding modeharmonic drive