For bipedal robots walking on uneven terrain, lack of information about a terrain may cause serious reduction of the stability. To solve the problem, the purpose of this paper is to develop a sensor which can be mounted on robot's soles and propose methods which can increase the stability of bipedal walk with the sensor. The sensor should detect information including relative posture and relative distance between the sole of the swing leg and the floor, when the robot execute the walk by ZMP-based control. In this paper, the sensor has been designed based on Net-Structure Proximity Sensor (NSPS) and a prototype has been developed. The developed sensor is with thin structure, light weight, less wirings (four wires only) and fast response (<1[ms]). Experimental results show that the sensor can output necessary relative posture and positon between the sole and the floor for walk control. Besides, the sensor has been mounted to the soles of a hobby robot and its feasibility is shown by controlling robot so that its sole can land on a tilted floor with maximum contacting area to improve the stability.
