A Practical Method for Controlling the Parallel Robot Path Based on the Sliding Mode Method with Fuzzy Adjustable Coefficients

Parallel manipulators are of interest in various industries due to their high precision, rigidity, high speed and low inertia. Controlling these types of systems faces challenges due to their complex and non-linear dynamics. Among the many methods of controlling the path of parallel manipulators, computed torque and sliding mode methods are the famous methods that are proposed. In practical applications, when the speed of the robot increases, adjusting the controller parameters is very difficult and depends on the working conditions of the robot, so the robot cannot work properly with fixed and predetermined coefficients under any condition. The type of path, the speed of the robot along the path, the initial conditions of the end effector of the robot in relation to the path, and even the sampling time are factors that affect the accuracy of the controller, and by changing each of them, it may be necessary to redefine the parameters of the control system and change the control coefficients. In this article, a method is presented which is based on the sliding mode method and the coefficients of the control system are adjusted appropriately by changing the sliding surface and sliding speed using the fuzzy method. The performance of this method has been investigated in two ways: modeling in MATLAB software and real time applying it to a planar parallel robot.