Abstract
In this paper, a robust output feedback tracking control scheme for motion control of uncertain robot manipulators without joint velocity measurement based on a second-order sliding mode (SOSM) observer is presented. Two second-order sliding mode observers with finite time convergence are developed for velocity estimation and uncertainty identification, respectively. The first SOSM observer is used to estimate the state vector in finite time without filtration. However, for uncertainty identification, the values are constructed from the high switching frequencies, necessitating the application of a filter. To estimate the uncertainties without filtration, a second SOSM-based nonlinear observer is designed. By integrating two SOSM observers, the resulting observer can theoretically obtain exact estimations of both velocity and uncertainty. An output feedback tracking control scheme is then designed based on the observed values of the state variables and the direct compensation of matched modelling uncertainty using their identified values. Finally, results of a simulation for a PUMA560 robot are shown to verify the effectiveness of the proposed strategy.
Highlights
Because sliding‐mode control is robust with respect to system uncertainties and has a fast transient response, it has received a great deal of attention from the research community [1,2,3]
This paper proposes a new output feedback controller scheme for uncertain robot manipulators based on a super‐twist second‐order sliding mode (SOSM) observer
We investigate an output feedback tracking control scheme for the uncertain robot manipulator expressed in Eq (1) based only on position measurement
Summary
Because sliding‐mode control is robust with respect to system uncertainties and has a fast transient response, it has received a great deal of attention from the research community [1,2,3]. Because of the advantages of high order sliding modes in terms of their ability to reconstruct exact, finite time derivatives, the super‐twist algorithm of the SOSM observer has been developed for use with mechanical systems [8,9,10,11,12], stepper motors [22] and helicopter systems [23] This type of observer ensures finite time convergence to the value of observed velocities without filtration but for uncertainty identification, the values are reconstructed from high switching frequency signals, necessitating the application of a filter.
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