Design of a Real Time Path of Motion Using a Sliding Mode Control with a Switching Surface

Abstract

Due to an increasing variety of tasks in production systems, the programming of robots becomes more complex. The aim of this work is, therefore, to simplify the work involved in programming of different contours as much as possible. Instead of specifying individual points of a contour in code, only one start and one end position are given. The movement between the two points is changed in real time by a robust control scheme, thus simplifying the programming effort for different contours. In this work, the robot is considered as a black box system and the approach to control consists only of considering the error of position and velocity without model. In the presented case, the development of the controller has shown that an Integral Sliding Mode Control (ISMC) strategy does not provide the desired control quality because of the presence of unavoidable saturating actuators in robots. Furthermore, a better result could be achieved with a Sliding Mode Control (SMC) approach that switches between two predefined surfaces. With this approach, good dynamic performances are obtained, in particular, in terms of overshoot which proves to be drastically reduced. Validations of the proposed method are obtained using real measurements realized on an industrial robot.