Semi-autonomous obstacle avoidance of omnidirectional wheelchair by joystick impedance control

An omnidirectional wheelchair is highly maneuverable in narrow or crowded areas such as residences, offices and hospitals. A semi-autonomous control method for omnidirectional wheelchairs is proposed. In addition to allowing the normal joystick commands of the wheelchair operator, this method provides a collision avoidance function using external sensors. The proposed method does not employ unexpected autonomous movements conflicting with the operator's joystick commands, because this tends to create discomfort for users and can be dangerous for infirm patients. Instead, the proposed method merely alerts the operator to the presence of an obstacle; this is accomplished by changing the impedance of the joystick essentially creating resistance against moving the joystick in the dangerous. direction. The wheelchair's motion remains controlled only by the operator's joystick commands, while a collision is avoided successfully. The effectiveness of the proposed method is shown by experiments with an onmidirectional wheelchair.