Design, Simulation and Experimental Validation of a Robust Controller on Different Inverted Pendulum Systems

Abstract

From the last five decades, inverted pendulum systems have been considered as a benchmark problem in the control literature due to their inherit nature of instability, nonlinearity and underactuation. Moreover, inverted pendulum dynamics closely resembles many real-time systems. Due to its applications in teaching and research experiments, a wide variety of inverted pendulum (IP) systems exist. To enhance the wealth of this robotic benchmark, this dissertation focuses on modeling and control of different inverted pendulum systems such as x-y-z, x-y, x-z, x and rotary inverted pendulum system. Dynamic mathematical modeling of different inverted pendulum systems are performed in which each system is linearized about its unstable equilibrium point i.e. vertically upright pendulum position and a state-space representation of each system is formed. Conventional modern controllers such as pole placement and LQR controllers are designed and implemented in real-time on rotary inverted pendulum. Further, to encounter the robustness issue in LQR controller, a novel robust LQR based ANFIS controller is proposed and validated on different inverted pendulum systems. Comparative simulation as well as experimental analysis of proposed controller with conventional controllers is done to validate the robustness of the proposed controller to pendulum mass, in which the proposed controller gives better performance in achieving lesser overshoot and settling time along with better robustness properties. Later, swing up problem of rotary inverted pendulum system is achieved using a nonlinear energy controller.