Sensor-Based Control of a Nine-Link Biped

TLDR

The study aims to achieve smooth 3‑D biped walking in a robot using sensor‑based control. The control strategy divides walking into sagittal and lateral motions, applies low‑gain optimal‑regulator feedback, and uses foot‑pressure and ankle‑torque sensors for force/torque feedback to regulate ankle torque and maintain smooth speed. Simulations and experiments on the BLR‑G2 robot confirm that the sensor‑based control produces smooth walking with firm foot contact.

Abstract

We aimed to realize smooth 3D biped walking in a robot through control based on information obtained from various sensors. We employed a method to control walking by divid ing it into motions in the sagittal plane and in the lateral plane. We treated motion in the lateral plane as a regulator prob lem with two equilibrium states. We also used relatively low gain feedback coefficients obtained from the optimal regula tor theory. For motion in the sagittal plane, we put the body speed close to the smooth speed function given in advance by controlling the ankle torque. The effectiveness of the proposed control method was ex amined by computer simulation and proved by experiments with our BLR-G2 walking robot. The BLR-G2 is equipped with foot pressure and ankle torque sensors to provide infor mation about the condition of contact with the floor. The sole and ankle driving actuators undergo force/torgue feedback control based on the sensor information. These contributed toward realizing smooth walking with the sole firmly gripping the floor.