Design of Fractional-Order PID Controller for Trajectory Tracking Control of Continuum Robots

Continuum robots are the behavioral extension of hyper-redundant robots usually inspired by living biological organs. These robots outperform their rigid counterparts regarding high flexibility, dexterity, and most importantly safe interaction. On the flip side, they are kinematically redundant, highly nonlinear, and multi-input, and consequently, their controlling remains a complex and challenging task. To this end, this paper proposes a Fractional-Order Proportional-Integral-Derivative (FOPID) controller to control the continuum robot's end-tip. The proposed controller is designed to control the inputs of a class of continuum robots, namely the Cable-Driven Continuum Robot (CDCR). To design the controller satisfactorily, the Particle Swarm Optimization (PSO) algorithm extracts the optimal values of the controller's parameters. The proposed FOPID controller's efficiency and control performance are demonstrated through two simulation examples: set-point tracking and point-to-point trajectory tracking. In addition, the obtained simulation results are compared to those provided by classical and Optimized PID controllers and to some available schemes. Given the obtained results, it is clear that the performances of the proposed FOPID controller are superior in tracking accuracy and smoothness in control signals.