Legged locomotion robot

• US 8,019,145 B2
• Filed: 03/27/2008
• Issued: 09/13/2011
• Est. Priority Date: 03/29/2007
• Status: Expired due to Fees

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company), Tokyo Institute of Technology (National University Corporation Tokyo Institute of Technology)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company), Tokyo Institute of Technology (National University Corporation Tokyo Institute of Technology)
• Inventors: Sugimoto, Shigeki, Okutomi, Masatoshi, Asatani, Minami
• Primary Examiner(s): RAHMJOO, MANUCHEHR
• Application Number:
  US12/056,502
• Publication Number:
  US 20080310705A1
• Time in Patent Office: 1,265 Days
• Field of Search: 382/153, 382/103, 382/106, 382/107, 318/568.11, 318/568.12, 318/568.1, 700/253, 700/245, 700/250, 700/254
• US Class Current: 382/153
• CPC Class Codes: B62D 57/032 with alternately or sequentially lifted supporting base and legs; with alternately or sequentially lifted feet or skid B62D57/024 takes precedence
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: G06V 20/64 Three-dimensional objects

Abstract

A robot capable of performing appropriate movement control while reducing arithmetic processing for recognizing the shape of a floor. The robot sets a predetermined landing position of steps of the legs on a present assumed floor, which is a floor represented by floor shape information used for a current motion control of the robot, during movement of the robot. An image projection area is set, and is projected on each image captured by cameras mounted on the robot for each predetermined landing position in the vicinity of each of the predetermined landing positions. Shape parameters representing the shape of an actual floor partial area are estimated, forming an actual floor whose image is captured in each partial image area, based on the image of the partial image area generated by projecting the set image projection area on the images captured by the cameras for each partial image area.

Claims

1. A legged locomotion robot, which is equipped with a camera for capturing surroundings including a floor ahead in a traveling direction of the robot and which moves while estimating a shape of the floor based on an image captured by the camera, comprising:

a predetermined landing position setting means which sets predetermined landing positions of a plurality of steps of legs of the robot on a present assumed floor which is the floor represented by floor shape information used for a current motion control of the robot during a movement of the robot;

an image projection area setting means which sets a flat image projection area to be projected on the image captured by the camera in a vicinity of each of the set predetermined landing positions therefor; and

a floor shape estimation means which estimates shape parameters representing the shape of an actual floor partial area, which is an actual floor captured within each partial image area, for each partial image area on a basis of the image of the partial image area generated by projecting the each set image projection area on the image captured by the camera.

2. The legged locomotion robot according to claim 1, wherein each of the image projection areas includes a ground surface of the leg of the robot in the set predetermined landing position.

3. The legged locomotion robot according to claim 1, wherein the shape parameters representing the shape of the actual floor partial area captured within the each partial image area include a posture parameter which represents a spatial posture on a plane including at least the actual floor partial area and a position parameter representing a spatial position on the plane.

4. The legged locomotion robot according to claim 3, wherein the camera includes two cameras and the floor shape estimation means estimates the shape parameters of the actual floor partial area corresponding to the image projection area in such a way as to determine a projective transformation matrix capable of transforming the image of the partial image area of one camera corresponding to the image projection area to an image coincident with the image of the partial image area of the other camera for the each set image projection area.

5. The legged locomotion robot according to claim 4, wherein the floor shape estimation means regards the shape parameters of the actual floor partial area corresponding to the partial image area as variable parameters in estimating the shape parameters of the actual floor partial area corresponding to arbitrary one of the set image projection areas, performs a convergence calculation of updating values of the variable parameters from initial values in such a way as to converge a plane defined by the values of the variable parameters into a plane including the actual floor partial area, while comparing an image generated by transforming the image of the partial image area of the one camera by using a temporary projective transformation matrix, which is determined according to values of the variable parameters, with an image of the partial image area of the other camera, and determines convergence values of the variable parameters obtained by the convergence calculation as estimated values of the shape parameters of the actual floor partial area corresponding to the partial image area.

6. The legged locomotion robot according to claim 5, wherein the floor shape estimation means includes a means which sets the initial values to values satisfying a limiting condition that should be satisfied by the initial values, where the limiting condition is that the plane defined by the initial values of the variable parameters is inclined with respect to the plane including the actual floor partial area.

7. The legged locomotion robot according to claim 6, wherein the plane defined by the initial values of the variable parameters has a tilt angle with respect to its horizontal plane equal to a given angle, which has been previously determined so as to deviate from a range of values that can be used as an actual tilt angle with respect to the horizontal plane of the plane including the actual floor partial area.

8. The legged locomotion robot according to claim 3, further comprising an inclined change portion identification means which identifies an inclined change portion where a degree of inclination of an actual floor ahead in the traveling direction of the robot changes, on a basis of the estimated shape parameters of the each actual floor partial area.

9. The legged locomotion robot according to claim 8, wherein the inclined change portion identification means includes:

a means which divides the actual floor partial areas corresponding to respective image projection areas into a first front-side group located nearer to the robot and a first back-side group located farther from the robot than the first front-side group and which performs the division in such a way as to minimize a distribution of the shape parameters of the actual floor partial areas belonging to the first front-side group and the distribution of the shape parameters of the actual floor partial areas belonging to the first back-side group;

a means which determines temporary representative values of the shape parameters of the actual floor partial areas belonging to the first front-side group obtained by the division and temporary representative values of the shape parameters of the actual floor partial areas belonging to the first back-side group and determines a degree of difference between two planes defined by the temporary representative values;

a means which determines a temporary inclined change portion as temporary values of the inclined change portion on a basis of the temporary representative values that define the two planes, respectively, in a case where the degree of difference between the two planes is determined to be high; and

a first inclined change portion identification means which identifies the inclined change portion on a basis of the shape parameters of the actual floor partial areas excluding an actual floor partial area close to the temporary inclined change portion from the actual floor partial areas belonging to the first front-side group and the shape parameters of the actual floor partial areas excluding an actual floor partial areas close to the temporary inclined change portion from the actual floor partial areas belonging to the first back-side group.

10. The legged locomotion robot according to claim 9, wherein the first inclined change portion identification means determines representative values of the shape parameters of the actual floor partial areas excluding the actual floor partial area close to the temporary inclined change portion from the actual floor partial areas belonging to the first front-side group and representative values of the shape parameters of the actual floor partial areas excluding the actual floor partial area close to the temporary inclined change portion from the actual floor partial areas belonging to the first back-side group and identifies an intersection between two planes defined by the representative values as the inclined change portion.

11. The legged locomotion robot according to claim 9, wherein the inclined change portion identification means includes:

a means which divides the actual floor partial areas corresponding to the image projection areas, respectively, into a second front-side group located nearer to the robot than a given position and a second back-side group located farther from the robot than the second front-side group in a case where the degree of difference between the two planes defined by the temporary representative values is determined to be low; and

a second inclined change portion identification means which identifies the inclined change portion on the basis of the shape parameters of the actual floor partial areas belonging to the second back-side group obtained by the division and information on the shape of a floor in the vicinity of a current ground contact point of the robot on the present assumed floor.

12. The legged locomotion robot according to claim 11, wherein the second inclined change portion identification means includes a means which determines representative values of the shape parameters of the actual floor partial areas belonging to the second back-side group and a means which determines the degree of difference between the floor in the vicinity of the current ground contact point of the robot on the present assumed floor and a plane defined by representative values of the shape parameters of the actual floor partial areas belonging to the second back-side group and, in the case where the means determines that the degree of difference between the floor and the plane is high, the second inclined change portion identification means identifies the inclined change portion on the assumption that the inclined change portion exists in the middle position between the predetermined landing position corresponding to the actual floor partial area closest to the second back-side group among the actual floor partial areas belonging to the second front-side group and the predetermined landing position corresponding to the actual floor partial area closest to the second front-side group among the actual floor partial areas belonging to the second back-side group.