Patent ID: 7643903

Claim:
A method of successively estimating the position of a floor reaction force acting point of each leg of a biped walking mobile body, comprising: a first step for successively grasping the position of the center of gravity of the biped walking mobile body, the position of the ankle joint of each leg, and the position of the metatarsophalangeal joint of the foot of the leg, respectively, and also successively grasping the vertical distance from the ankle joint to a ground contact surface of each leg in contact with the ground while the biped walking mobile body is in motion, a first ground contact sensor and a second ground contact sensor being provided on the sole of the foot of each leg of the biped walking mobile body, and the first and the second ground contact sensors outputting ground contact detection signals based on whether a place directly below an ankle joint of a leg and a place directly below a metatarsophalangeal joint of the foot of the leg, respectively, are in contact with the ground; and a second step wherein, for each leg in contact with the ground while the biped walking mobile body is in motion, the horizontal position of one of the center of gravity, the ankle joint of the leg, and the metatarsophalangeal joint of the leg, the positions thereof having been determined in the first step, is successively estimated selectively as the horizontal position of the floor reaction force acting point of the leg on the basis of at least the combination of contact or no contact with the ground indicated by a ground contact detection signal of the first ground contact sensor and contact or no contact with the ground indicated by a ground contact detection signal of the second ground contact sensor of each leg, and the vertical position of the floor reaction force acting point of the leg is successively estimated as the position apart vertically downward from the ankle joint by the vertical distance from the ankle joint to the ground contact surface of the leg determined in the first step.