Abstract
This paper describes a method for adapting to rough terrain for biped robots. The robots obtain information of reaction force from the ground by sensors located at each corner of rectangular soles. From the sensor information, environmental modes are extracted. The environmental modes consist of four modes: heaving, rolling, pitching, and twisting, which represent contact states between the ground and the soles. On the basis of the twisting mode, the robot detects the unevenness of the ground, makes contact with the uneven ground stably with three corners of the sole, and modifies the trajectory to continue stable walking. The validity of the proposed method is confirmed by experimental results.