A nonlinear fractional order PID controller applied to redundant robot manipulator

The Redundant robotic systems are multi-input multi-output (MIMO), highly nonlinear and coupled systems. In presence of un-modeled dynamics such as parameter variation and external disturbance, the performance of the system is badly affected. Consequently, robust controller design for these systems is an intriguing task for control researcher to handle such complexities present in the system. This research study presents the nonlinear fractional order PID (NL-FOPID) controller for 5-DOF redundant robot manipulator for joint trajectory tracking task. The optimal controller parameters are achieved using recent artificial bees colony (ABC) optimization technique. For examining the effectiveness of the NL-FOPID controller, the robustness testing is also investigated for parameters variation and external disturbance. After many numerical simulations, the simulation results clearly show that the performances of proposed NL-FOPID controller are superior to nonlinear PID (NL-PID) controller, and traditional linear PID.