New Sliding Mode Controller for Robotic Manipulator Subjected to Disturbance and Uncertainty

Abstract

This article presents a new sliding mode controller (SMC) for the position control of a robotic manipulator subjected to perturbations, such as parameter uncertainties and extraneous disturbances. The SMC is designed so that the sliding mode condition is satisfied and integrated with the perturbation estimator. The estimator is formulated by adopting a concept of the integrated average value of the imposed perturbation over a certain sampling period and realized using the Taylor series. In the formulation of the estimator, the relationship between control performance and sensor performance is established by adjusting the sampling ratio. Subsequently, in order to improve control performance, the actuating condition for the estimator is introduced: on-off switching condition (OSC). This condition is decided on the basis of the estimation error between actual and predicted values. By imposing the OSC, control accuracy can be enhanced when high frequency perturbations exist in the system. The benefits of the proposed methodology are demonstrated on a two-link planar manipulator. The position control performances of the manipulator are evaluated and compared between the proposed methodology and conventional control schemes.