We have been studying an omnidirectional driving gear mechanism that can generate thrusting force in an arbitrary direction on one surface, which may be flat or curved. This omnidirectional gear is driven by spur gears that are perpendicular. When one spur gear rotates to drive the omnidirectional gear, the other slides between the teeth of the omnidirectional gear and vice versa. In this paper, we introduce gears with passive rollers to reduce the frictional resistance with a mechanism including smooth rolling motion of conical or flat passive rollers, which can boost the power transmission efficiency of the omnidirectional driving gear system. We also confirmed another useful function of this gear with passive rollers as a worm wheel to transmit power from a worm gear with higher energy efficiency than an ordinary worm wheel.

This video shows multiple omnidirectional driving gears to realize smaller size and weight than the ordinary X-Y stages. The examinations of different materials and sizes of the gear teeth to improve the performances of the omnidirectional driving gears are the main progress of this paper from our previous reports [1].

In this paper, the principles and the actual configurations of the omnidirectional driving gear mechanism that was implemented by the authors were described. The validity of the proposed structure was also confirmed and its basic characteristics understood through experiments using the actual prototypes.

As ordinary dual-axis driving mechanisms in X-Y directions, for example, commercially available X-Y stages with ball screws are familiar. However, such driving mechanisms have two stages, namely both upper and lower linear actuators, the latter of which must generate sufficient thrust to carry large weights, including that of the upper actuator mechanism, which has hampered efforts to achieve suitably fast and smooth driving motion due to the inertial force effect. It is also difficult to achieve a small and slimline driving mechanism with such overlapping two-stage structure. In these ordinary two-stage driving mechanisms, the motion of the X-Y stage can be disturbed by the wires of the upper actuator. In this research, we have considered the abovementioned problems, and propose a new omnidirectional driving gear mechanism that enhances its driving area from the normal X-Y plane to convex and concave curved surfaces respectively, and even various combinations of both. The smoothness of basic omnidirectional motion and effectiveness of the driving method of this proposed omnidirectional driving gear mechanism have been confirmed with several experiments involving our setups.

In this paper, additional manipulating function for limited narrow space with omnidirectional driving gear was described. The validity and advantage of the proposed function was also confirmed through experiments using the actual prototype of the planar omnidirectional driving gear units for the parallel gripper.