Controller for mobile robot

1. A mobile robot, which has a base body, a plurality of movable links extended from the base body, joints respectively provided between a distal end portion of each of the movable links and the base body, and an attitude sensor which detects an attitude of the base body, the mobile robot being configured such that the distal end portion of each of the movable links is moved with respect to the base body by a motion of the respective joint,

the mobile robot further including a controller, the controller comprising a processor and a memory, the memory having a program installed thereon that, when executed by the processor, causes the controller to function as:

a motion target determining unit, which sequentially determines, in the case where the mobile robot climbs up or down a structure to be climbed up or down, a motion target that defines the motion of each joint of the mobile robot so as to include a climbing up and down motion in which distal end portions of upper movable links to be supported, which are one or more movable links extended from an upper portion of the base body among the plurality of movable links, and distal end portions of lower movable links to be supported, which are one or more movable links extended from a lower portion of the base body, are brought into contact with the structure thereby to be supported, and in a state wherein distal end portions of movable links to be moved, which are one or more movable links other than the upper movable links to be supported and the lower movable links to be supported, are positioned away from the structure, the distal end portion of each of the movable links to be moved is moved toward a desired support position and attitude to bring the distal end portion of the movable link to be moved into contact with the structure at the desired support position and attitude thereby to be supported;

a joint control unit that controls the motion of each joint of the mobile robot according to the determined motion target; and

a difference estimation unit which estimates, in the climbing up and down motion of the mobile robot, as actual position and attitude of at least one of the distal end portion of each of the lower movable links to be supported and the distal end portion of each of the movable links to be moved, the position and attitude of at least one of the distal end portion of each of the lower movable links to be supported of the mobile robot and the distal end portion of each of the movable links to be moved thereof which is obtained by virtually rotating the mobile robot of the motion target, using as a center of rotation, an action center point of overall load applied from the structure to the distal end portion of each of the upper movable links to be supported by a difference between a detection value of the attitude of the base body indicated by an output of the attitude sensor and a desired value of the attitude of the base body in the motion target, and the difference estimation unit outputs at least one of a first position and attitude difference and a second position and attitude difference, the first position and attitude difference being a difference between the estimated actual position and attitude of the distal end portion of each of one or more lower movable links to be supported in the climbing up and down motion of the mobile robot and the desired position and attitude of the distal end portion of the lower movable link to be supported in the motion target, the second position and attitude difference being a difference between the estimated actual position and attitude of the distal end portion of each of one or more movable links to be moved in the climbing up and down motion of the mobile robot and the desired position and attitude of the distal end portion of the movable link to be moved in the motion target;

wherein the motion target determining unit determines the motion target such that, at the time of sequentially determining the motion target in the climbing up and down motion of the mobile robot, at least one of desired relative position and attitude of the distal end portion of each of one or more lower movable links to be supported with respect to the base body and desired support position and attitude at which the distal end portion of each of one or more movable links to be moved is to be supported by the structure is adjusted according to at least one of the first position and attitude difference and the second position and attitude difference.

2. The mobile robot according to claim 1 ,

wherein the mobile robot has two or more movable links extended from the lower portion of the base body and two or more movable links extended from the upper portion of the base body, and

the climbing up and down motion is a climbing up and down motion in which some movable links among the movable links extended from the lower portion of the base body are defined as the lower movable links to be supported, the remaining movable links among the movable links extended from the lower portion of the base body are defined as the movable links to be moved, and at least one movable link among the movable links extended from the upper portion of the base body is defined as the upper movable link to be supported, and the distal end portions of the movable links to be moved are moved.

3. The mobile robot according to claim 2 ,

wherein the motion target determining unit is configured such that, in the case where the estimated position and attitude difference is a difference caused by the attitude of the base body inclined to bring the lower portion of the base body close to the structure, the desired relative position/attitude of the distal end portion of the lower movable link to be supported with respect to the base body is adjusted such that a distance between a part of each of one or more lower movable links to be supported among the movable links extended from the lower portion of the base body, which part being connected to the base body, and the distal end portion of the lower movable link to be supported is longer than that in the case where the position and attitude difference is zero, and the desired support position/attitude of the distal end portion of each of the one or more movable links to be moved among the movable links extended from the lower portion of the base body are adjusted such that the desired support position/attitude are brought closer to the base body than in the case where the position and attitude difference is zero.