Development of an intelligent power assisted wheelchair using fuzzy control systems

Powered wheelchairs are popular mobility aids for most disabled patients and elders. Most of powered wheelchairs are manipulated via a conventional joystick. The powered wheelchair user has to control the direction and velocity of a powered wheelchair in a very narrow joystick operation range. Therefore, the user's joystick command may be very sensitive to the wheelchair motions. In addition, such an operation is not analog to conventional manual wheelchairs. In this paper, a power assisted wheelchair control system is developed to perform similar operations of manual wheelchairs, while the efforts of pushing wheel rings are significantly reduced for the flat and barrier free ramp terrains. For the proposed power assisted control system, electric motors are driven according to the tactile forces between user's hands and wheel rings. The tactile forces are further combined with slopes of ramps and resistances of operations to generate wheel velocities in terms of an intelligent fuzzy control system. Therefore, the proposed power assisted wheelchair not only maintains user's motor function of upper limbs but also performs easy driving for a long distance. The performance is evaluated practically using an electromyogram (EMG) instrument that is used to measure the muscle activities of volunteers on their upper limbs. Experiment results show that the power assisted function significantly reduces the pushing or pulling forces under flat and barrier free ramp terrains.