Variable Structure Control of Robot Manipulators with Perturbation Estimator

The idea of perturbation compensation is incorporated in variable structure control (VSC) of robot manipulators to cancel the effects of system parametric uncertainties and external disturbances and hence alleviate control chattering. By using the dynamic response of the robot as characterized by the sliding function, a technique is proposed to deduce the system perturbation signal. For practical implementation, a perturbation estimator is introduced to approximate the system uncertainties. Estimates of the bounds on modelling errors and external disturbances are not required while signal measurement uncertainties can be accommodated. The suggested VSC law ensures that the robot control system reaches the sliding mode in finite time and with prescribed transient behaviour. Detailed computer simulation results are presented to demonstrate the effectiveness of this new approach.