An adaptable optimal controller for electric wheelchairs.

A microcomputer-based optimal control system for electric wheelchairs is presented. As the weight of a wheelchair is generally small compared to that of a user, the user's actual weight can have a tremendous impact on the dynamics of the wheelchair. The velocity feedback controller presented here was designed to give an optimal response for all users by incorporating a measure of the individual user's weight into the control algorithm. This allows optimal control of the motor velocities while assuring the constant stability of the system. Control of the system is managed by a modified proportional-integral-derivative (PID) controller, and the adaptability is handled by use of variable-structure control. The factors and considerations involved in such a system are identified, as are the advantages and disadvantages of the particular control strategy used. Experimental results are presented.