Collision Avoidance in an Omni-Directional Wheelchair by using Haptic Feedback

The present paper gives a haptic feedback control of a holonomic Omni-directional Mobile Wheelchair (OMW) with a haptic joystick for the operation of disabled people or elderly people considering not only the navigation task but also user’s safety. In the present research a haptic joystick was designed and applied with being maneuverable for users and free of joystick’s vibrations. A way to build the local map around OMW is presented by considering the reliability of sensors data such as ultrasonic and PSD sensor. If an obstacle is detected in the direction of movement based on the local map information, the impedance of the joystick in this direction is changed. Namely, the closer the obstacle is the bigger the impedance value becomes. By this function, users spontaneously understand that they are in risk of obstacle collision and then users can change the direction of movement by their decision in order to avoid it. Two navigation modes are considered: one of them allows the user to approach a desired goal, and the other protects the user from obstacle collision. The proposed approach is thought to be reasonable as a man-machine existing control system.