Application of Fuzzy Sliding Mode Control with Moving Sliding Surface to Rotary Inverted Pendulum

Abstract

In this study, considering the dynamic equations of the rotary inverted pendulum system and the motor dynamics, the pendulum angle is controlled with fuzzy logic sliding mode control method which has moving sliding surface by using state variables in the Matlab program. The sliding surface of the sliding mode control method is selected as moving. A fuzzy logic structure is used to calculate the slope of the slip surface. The boundary values of the membership functions in the fuzzy logic structure have been optimized using the genetic algorithm codes in the Matlab program. The sum of the squares of the errors is preferred as the objective function. The inputs of the fuzzy logic structure are the error of the pendulum angle and the derivative of the pendulum angle error. In the fuzzy logic structure, the slope of the sliding surface of the sliding mode control structure is obtained as an output. From the results, it was seen that the pendulum angle reached the desired reference value around the first second and the error was approximately zero. In addition, it has been observed that the motor torque value is at the levels of 20 Nm and the motor current value is at the levels of 3 ampers. It has been obtained from the results that the motor values are at reasonable levels close to the values in practical applications. When the motor is selected according to these obtained values, there won't be a problem with the implementation of this control method in real-time applications of the rotary inverted pendulum system.