A modified PID algorithm for dynamic control of an automatic wheelchair

This paper presents the implementation of dynamic control of an automatic wheelchair. The control objective is to control the velocities of the left and right wheels to follow the desired velocity commands. The equations of motion of the wheelchair are derived. The proportional-integral-derivative (PID) control algorithm is applied by utilizing incremental encoders as the feedback of the velocities of both wheels. The analysis of the closed-loop system shows that the PID algorithm is applicable to control the velocities of the wheelchair. The PID parameters are tuned based upon the open-loop Ziegler-Nichols method. In the implementation, the control algorithm is modified by limiting the input rate to prevent the windup. The experimental results show that the effectiveness of the algorithm.