Fractional Order PID Controller for a 2DoF Rotary Torsion Plant

In this work, a Fractional Order Proportional-Integral-Derivative (FOPID) controller is proposed to control the rotational load's angular position in a 2 degree of freedom (2DoF) rotary torsion plant. The 2DoF torsion system which is used here consists of torsion modules that have flexible coupling connected to the shaft of a DC servo motor. Here the linear dynamics of a 2DoF torsional plant is obtained. Then a FOPID controller is developed for position control, in which method of Particle swarm optimization (PSO) technique is used to tune the parameters of this controller. FOPID controllers have been shown to be more robust to parameter variations, external disturbances, and modeling errors than traditional PID controllers. The effectiveness of the proposed FOPID control system is compared to that of the traditional PID and 2DoF PID control systems. Robustness analysis is also done with the developed controller. As per the results obtained in simulation, controlled output of proposed FOPID controller presents no overshoot, less settling time, and zero steady-state error in comparison to the the conventional PID, and 2DoF PID control systems.