Frictional drive device and inverted pendulum type vehicle using the same

#The present invention relates to a frictional drive device and an inverted pendulum type vehicle using the same as a drive unit.

#Known is an inverted pendulum type vehicle or an omni-directional vehicle incorporated with a frictional drive device which comprises a pair of drive assemblies individually actuated by electric motors and a main wheel held between the drive assemblies and frictionally driven by the drive assemblies. See WO2008/132779A1 (US20100096905A1) for instance. Each drive assembly comprises a drive disk coaxially opposing the drive disk of the other drive assembly and a plurality of drive rollers obliquely arranged along the circumference of the drive disk at a regular interval so as to be individually rotatable. The main wheel comprises a ring-shaped annular member rotatably supported by a frame around a central axial line thereof and a plurality of driven rollers arranged along the circumference of the annular member so as to be rotatable around the respective tangential lines. As the drive disks are turned by the electric motors, the driven rollers are frictionally driven by the drive rollers. When the drive rollers are turned around the tangential directions of the main wheel, the vehicle is driven in a lateral direction. When the main wheel is turned around the central axial line thereof, the vehicle is driven in a fore and aft direction. The direction of motion of the vehicle can be selected as desired by suitably adjusting the difference between the rotational speeds of the two drive disks.

#In such a frictional drive device, the driven roller or driven rollers engaging the road surface or the object to be actuated are engaged by at least one of the right drive rollers and at least one of the left drive rollers so that the traction force or drive force can be obtained at all times. In this regard, it is highly important that the slippage between the drive rollers and driven rollers to be minimized in achieving a high efficiency of the frictional drive device and increasing the traction or drive force which the frictional drive device is capable of delivering.

#Now the present invention is described in the following with reference to the appended drawings, in which:

#FIG. 1 is a sectional front view of an inverted pendulum type vehicle incorporated with a frictional drive device according to the present invention for a drive unit thereof;

#FIG. 2 is an enlarged sectional front view of the frictional drive device;

#The frictional drive device according to the present invention and the vehicle incorporated with the frictional drive device is in large part symmetric with respect to a central longitudinal plane, and various components are used in pairs, one on the right hand side and the other on the left hand side. Such components are denoted with numerals with a suffix L or R, L indicating the component being on the left hand side and R indicating the component being on the right hand side. Therefore, only one of each of such pairs may be described in the following by denoting the component with a numeral without a suffix, instead of repeating the same description with respect to the other of the pair. These numerals may also be used without the suffix in the following description to denote such components collectively.

#Referring to FIG. 1, an inverted pendulum type vehicle embodying the present invention comprises a columnar frame 10 having a drive unit 40 incorporated in a lower part thereof. A lower part of the frame 10 is provided with a pair of steps 12 extending from either side thereof, and an upper end of the frame 10 is provided with a handle bar 14 extending laterally from either direction. Each lateral end of the handle bar 14 is provided with a grip 16.

#The drive unit 40 is configured as a unicycle drive unit, and is interposed between a pair of side walls 18 of a lower part of the frame 10. A control unit not shown in the drawings controls the operation of the drive unit 40 according to the output signals of a gyro sensor and a load sensor (not shown in the drawings) so that the frame 10 is maintained in an upright posture as an inverted pendulum type vehicle in operation and is enabled to travel in both a fore and aft and lateral direction.