Impedance control for safety and comfortable navigation of an omni-directional mobile wheelchair

The present paper gives a haptic feedback control of a holonomic omni-directional mobile wheelchair (OMW) with a haptic joystick for the operation of disable people or elderly people considering not only the navigation task but also user's comfort and safety. In the present research a haptic joystick was designed and applied with being maneuverable for users and free of joystick's vibrations. If an obstacle is detected in the direction of movement, 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. Furthermore, for the command input by human joystick operation, velocity control of OMW is executed by means of frequency shaped control to achieve the comfort drive for users. The proposed approach is thought to be reasonable as a man-machine existing control system.