Design, implementation, and testing of an adaptable optimal controller for an electric wheelchair

The authors present the design, implementation, and testing of an adaptable, optimal controller for the electric wheelchair. Optimal control theory and pattern recognition techniques are combined to design a variable-structure controller (VSC) using a modified proportional, integral, and derivative (PID) control method. The controller is adaptable in the sense that multiple sets of control coefficients are used, with each set being optimized for a specific range of wheelchair load parameters. The appropriate set of control coefficients can be automatically selected on the basis of load parameter estimates to provide a self-adaptive controller, or manually selected prior to installation to tailor the chair to a particular user. The manually adaptable controller is implemented in a microprocessor-based system, installed on an electric wheelchair, and its performance is experimentally verified.<>