A joystick type car drive interface for wheelchair users

This paper presents a joystick car drive system for a handicapped person using a wheelchair. The joystick drive system enables handicapped person to drive a car with his/her single hand. The joystick operation in back and force direction controls acceleration or deceleration of a car while that in left and right direction turns a steering wheel. Therefore a person, who has disabilities in legs together with some disabilities such as not enough force nor move their arms in wide area, can drive a car by oneself. Additionally, a wheelchair driver does not have to change seat from a wheelchair to a car seat. The developed van equips with a lift on the back and wheelchair user can access to the drivers position with propelling a wheelchair inside of a van. For maintaining driving safety of a van in case of system fault, battery fault, etc., gas and brake pedals are physically moved by mechanical linkage which is connected to a joystick lever. Therefore a van can be stopped by manual operation in any case. A steering wheel is driven by an electric motor which is controlled by a micro-computer system. A steering angle is controlled by PID feedback to track the reference angle given by a joystick. To realize the joystick drive system, we design a steering drive mechanism which includes a DC motor, a magnetic clutch, and a potentiometer for steering angle detection, and transmission gears. Most of cars manufactured in these days equip with power steering systems which reduce steering operation power of a human driver. Therefore the developed system can utilize the power steering system for realizing the joystick car drive system with minimum capacity of a motor. The prototype mechanism is mounted on a actual van type car and tested a realizability of the proposed joystick car drive system.