Virtual restraint of hand position and posture for cooperative virtual object manipulation with ungrounded force display device

In cooperative object manipulation in shared virtual environments with ungrounded force display devices, a holding object is involuntarily released when the remote users move apart. That is caused by excessive virtual force generated by an uninhibited increase in distance between the users and virtual coupling. This study proposes an object manipulation assistance method that virtually restrains remote users´ hand positions and postures. Hand positions and postures are adjusted to partially match the virtual hands. To assist the recognition of restraint between users´ hands, a method of enhancing the restraint force is also proposed. The results of the evaluation experiments indicated the feasibility for improving task performance in cooperative object manipulation.