In this paper, riding comfort of an omnidirectional wheelchair (OMW) driven by joystick is studied for the case when OMW moves in X direction, Y direction, or in a slanting direction. In order to achieve the comfort driving specific spectrum elements such as natural frequency of OMW and discomfort frequency of human organs are suppressed. In order to evaluate the comfort, a human model which considers human upper body composed of two parts: torso and head, has been developed and used in order to test the effectiveness of the proposed approach. Experimental results of velocity control are shown.

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.

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.