Minimising tremor in a joystick controller using fuzzy logic.

We have designed and built a fuzzy logic controller which minimizes the effect of Multiple Sclerosis (MS) hand tremors. The aim of our project has been to give people with Multiple Sclerosis better control of an electric wheelchair by removing tremors from the joystick signal. The system intercepts the signal from the joystick and then passes it through the fuzzy logic controller. The fuzzy logic rules identify and reduce erratic or unusual movements, employing a history mechanism to determine what `unusual' is. The fuzzy logic then outputs a signal which most closely represents the intent of the user. This paper reports on the latest experiments conducted with our prototype wheelchair, using test volunteers with MS, as well as on the design of a new fuzzy logic controller.