Mobile robot

• US 7,658,245 B2
• Filed: 11/20/2007
• Issued: 02/09/2010
• Est. Priority Date: 11/20/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Amino, Azusa, Nakamura, Ryosuke
• Primary Examiner(s): Morris; Lesley D
• Assistant Examiner(s): ADAMS, TASHIANA R
• Application Number:
  US11/942,994
• Publication Number:
  US 20080135312A1
• Time in Patent Office: 812 Days
• Field of Search: 180 81- 86, 744/90, 744/903, 901/1
• US Class Current: 180/8.3
• CPC Class Codes: B62D 57/028 having wheels and mechanical legs B62D57/024 takes precedence; ground-engaging vehicle fittings for supporting, lifting or manoeuvring the vehicle, wholly or in part B60S9/00

Abstract

There is provided a high-speed and stable robot apparatus realizing stable walking by surely grounding legs having wheels even on an irregular ground surface. The mobile robot includes a body having a control device and an inclination angle detecting device which detects an inclination angle and an angular velocity, and the plurality of legs each having a thigh part and a lower limb part. The thigh part is rotatable around an X-axis, which is a front direction with respect to the body, and around a Y-axis which is a side surface direction with respect to the body. The robot comprises wheels rotatable around the Y-axis and movable supporting parts rotatable around the Y-axis and capable of being grounded on a road surface, which are provided on lower portions of the lower limb parts. The robot switches its operation according to irregularities of the road surface between coaxial two-wheeled inverted pendulum control operation of moving with the wheels without grounding the movable supporting parts while maintaining the inversion and bipedal walking control operation of walking by controlling the grounding of the wheels and the movable supporting parts on the road surface.

Claims

1. A mobile robot comprising:

a body having a control device and an inclination angle detecting device which detects an inclination angle and an angular velocity of the body with respect to a gravity direction;

a plurality of legs each having a thigh part and a lower limb part, the thigh part being rotatable around an X-axis, which is a front direction with respect to the body, and around a Y-axis which is a side surface direction with respect to the body;

a wheel provided on a lower portion of the lower limb part and rotatable around the Y-axis;

a movable supporting part provided on the lower portion of the lower limb part separately from the wheel and rotatable around the Y-axis to be grounded on a road surface; and

said robot switching its operation according to irregularities of the road surface between coaxial two-wheeled inverted pendulum control operation of moving with the wheels without grounding the movable supporting parts while maintaining inversion, and bipedal walking control operation of walking by controlling the grounding of the wheels and the movable supporting parts on the road surface, said bipedal walking control operation moving said legs while effecting a complete grounding state that the wheels are grounded while being prevented from rotating and the movable supporting parts are also grounded on the road surface, and a wheel grounding state that the wheels are grounded while being permitted to rotate and the movable supporting parts are floated from the road surface.

2. The mobile robot according to claim 1, wherein, when the road surface has few irregularities, the robot folds the movable supporting parts on a side of the wheels without grounding and performs wheel traveling under the coaxial two-wheeled inverted pendulum control operation.

3. The mobile robot according to claim 1, wherein said legs are controlled in a manner that, when the leg is lowered to be grounded during the bipedal walking control operation, the leg is brought into the wheel grounding state that the wheel is grounded while being permitted to rotate and the movable supporting part is floated from the road surface, and the wheel is stopped rotating when a rotation speed of the wheel is a fixed value or less, or when an amount of rotation by the wheel is a fixed value or more.

4. The mobile robot according to claim 1, wherein right and left legs are provided as said legs, and movement of the legs is controlled by the steps of:

(1) raising the right leg and bringing the left leg into a complete grounding state that the wheel of the left leg is grounded on the road surface while being prevented from rotating and the movable supporting part is also grounded on the road surface, to support the whole body of the robot;

(2) lowering the right leg, bringing the right leg into a wheel grounding state that the wheel of the right leg is grounded on the road surface while being permitted to rotate and the movable supporting part of the right leg is floated from the road surface, and searching a point where the right leg is to be grounded, in a manner that when a rotation speed of the wheel is a fixed value or less, or when an amount of rotation performed by the wheel is a fixed value or more, the wheel is stopped rotating;

(3) completely lowering the right leg and bringing both the legs in the complete grounding state to support the whole body of the robot;

(4) raising the left leg and bringing the right leg in the complete grounding state to support the whole body of the robot;

(5) lowering the left leg, bringing the left leg into the wheel grounding state that the wheel of the left leg is grounded on the road surface while being permitted to rotate and the movable supporting part of the left leg is floated from the road surface, and searching a point where the left leg is to be grounded, in a manner that when a rotation speed of the wheel is the fixed value or less, or when an amount of rotation performed by the wheel is the fixed value or more, the wheel is stopped rotating; and

(6) completely lowering the left leg and bringing both the legs in the complete grounding state to support the whole body of the robot.

5. The mobile robot according to claim 1, wherein right and left legs are provided as said legs, and the wheels are driven by motors having an angle detecting function.

6. A mobile robot comprising:

a body having a control device and an inclination angle detecting device which detects an inclination angle and an angular velocity of the body with respect to a gravity direction; and

a plurality of legs each having a thigh part and a lower limp part, the thigh part rotatable around an X-axis which is a front direction with respect to the body, and around a Y-axis which is a side surface direction with respect to the body, a wheel provided on a lower portion of the lower limb part for rotation around the Y-axis, and a movable supporting part provided separately from the wheel on the lower portion of the lower limb part and movable separately from the wheel for rotation around the Y-axis,

wherein;

when a road surface has few irregularities, a coaxial two-wheeled inverted pendulum control operation is performed to fold the movable supporting parts on a side of the wheels of the legs and travel with the wheels without grounding the movable supporting parts on the road surface, and

when the road surface has large irregularities, a bipedal walking control operation is performed to walk with the legs in one of a complete grounding state and a wheel grounding state, the complete grounding state indicating that the wheels are grounded on the road surface while being prevented from rotating and the movable supporting parts are grounded on the road surface, and the wheel grounding state indicating that the wheels are grounded while being permitted to rotate and the movable supporting parts are floated from the road surface.

7. The mobile robot according to claim 6, wherein right and left legs are provided as the legs, and the wheels are driven by motors having an angle detecting function.

8. The mobile robot according to claim 7, wherein the bipedal walking control operation is performed by shifting the following states:

(1) raising the right leg and bringing the left leg into the complete grounding state that the wheel of the left leg is grounded on the road surface while being prevented from rotating and the movable supporting part is also grounded on the road surface, to support the whole body of the robot;

(2) lowering the right leg, bringing the right leg into the wheel grounding state that the wheel of the right leg is grounded on the road surface while being permitted to rotate and the movable supporting part of the right leg is floated from the road surface, and searching a point where the right leg is to be grounded;

(3) completely lowering the right leg and bringing both legs in the complete grounding state to support the whole body of the robot;

(4) raising the left leg and bringing the right leg in the complete grounding state to support the whole body of the robot;

(5) lowering the left leg, bringing the left leg into the wheel grounding state that the wheel of the left leg is grounded on the road surface while being permitted to rotate and the movable supporting part of the left leg is floated from the road surface, and searching a point where the left leg is to be grounded; and

(6) completely lowering the left leg and bringing both legs in the complete grounding state to support the whole body of the robot.