Legged mobile robot and control method thereof, leg structure of legged mobile robot, and mobile leg unit for legged mobile robot

A foot structure for a legged mobile robot having at least a plurality of movable legs, the foot structure comprising:

• a foot frame having a generally planar structure,
• a sole cushioning body, disposed on the sole of the foot frame, having non-linear elastic characteristics with an area having a relatively large deformation for an initial period and an area having a relatively small deformation subsequent to the initial period, and
• an ankle connection unit, disposed on the approximate center of the top surface of the foot frame, for linking the foot frame to the movable leg of the legged mobile robot.

A legged mobile robot including at least a pair of left and right movable leg units for performing a bipedalling job, the movable leg unit comprising:

• at least one joint actuator for accomplishing degrees of freedom at a movable leg,
• an inner support body having a first rigidity for supporting the joint actuator on the inside of the legged mobile robot body, and
• an outer support body, having a second rigidity relatively larger than the first rigidity, for supporting the joint actuator on the outside of the legged mobile robot body.

A movable leg unit used in a left and right pair in a legged mobile robot performing a legged job, the movable leg unit comprising:

• at least one joint actuator for accomplishing degrees of freedom at a movable leg,
• an inner support body having a first rigidity for supporting the joint actuator on the inside of the legged mobile robot body, and
• an outer support body, having a second rigidity relatively larger than the first rigidity, for supporting the joint actuator on the outside of the legged mobile robot body.

A method of controlling a legged mobile robot having at least two movable legs, the method comprising a ZMP behavior space control step for controlling a ZMP behavior space defined by a ZMP position at which a pitch axis moment and a roll axis moment of the body of the robot become zero and by a floor reaction force of a floor surface acting on the robot body,

• wherein the ZMP behavior space control step causes beforehand a predetermined distortion or predetermined characteristics to the ZMP behavior space.

A method of controlling a legged mobile robot having at least two movable legs, the method comprising the step of defining a ZMP behavior space by a ZMP position at which a pitch axis moment and a roll axis moment of the body of the robot become zero and by a floor reaction force of a floor surface acting on the robot body,

• the step of determining a stable ZMP position based on the definition of the ZMP behavior space, and
• the step of controlling the operation of the robot body based on the determined stable ZMP position.