“…The main drawback of these open-loop techniques is that they cannot cope with various external disturbances that exist in the actual operational environment. Hence, closed-loop control techniques such as proportional integral derivative (PID) and its invariants, 14–16 model predictive control (MPC), 17–19 sliding mode control (SMC), 20–22 adaptive control, 23–25 intelligent control 14,26,27 and instantaneous optimal control, 28 are more practical. Input saturation, as well as constraints on trolley velocity and sway angles for safety consideration, 9,19,29 are well-considered in the above controllers.…”