Frequency shape control of omni-directional wheelchair to increase user's comfort

An omni-directional wheelchair is highly maneuverable in narrow or crowded areas such as residences, offices and hospitals. However, with the increase in the degrees of freedom accompanying omni-directional wheelchairs, it has become more important than in the past to develop a smooth and vibrationless motion control system. This paper presents a novel motion control method for an omni-directional wheelchair considering the suppression of vibration of both the wheelchair and the user. In the proposed control system, the vibration of the wheelchair is suppressed by notching the frequency characteristics at the natural frequency of both the wheelchair and human's organs. The designed controller satisfies various control specifications such as settling time and stability by using feedback from only the wheelchair's position data. The effectiveness of the proposed system is evaluated by the output signal of a sensor attached to the wheelchair and by a descriptive inspection of several users.