Robust stabilization and tracking control of spatial inverted pendulum using super-twisting sliding mode control

Spatial inverted pendulum (SIP) is recently found in the control literature. Its dynamic model shows that it is more generalized form as compared to other existing inverted pendulums. Controlling inverted pendulums is a challenging task as they are unstable, non-linear and under-actuated systems. SIP has five degrees of freedom with three control forces due to which it is a multi-input and multi-output system. Sliding mode control is best suited to achieve robust stability and robust performance for non-linear, stable and unstable processes. In the present work, an enhanced sliding mode control technique is proposed to achieve the trajectory tracking and robust stabilization of spatial inverted pendulum. In the proposed control structure, three different control blocks are involved that are tuned using whale optimization algorithm. Through various simulations, it is found that the proposed method yields significantly improved tracking performance and enhanced robustness toward process parameter perturbations and load disturbances compared to recently reported control strategy.