Performance of a Thermal Bipedal Walker on Inclined Surfaces with Different Leg CoMs

This paper investigates the walking performance of a thermal walker on various inclined surfaces. The thermal walker can walk only by ground heat energy using bimetal sheets. The walking performance on slopes is analyzed using a simplified walker model. The analytical result is compared with the two sets of walking experiments, on slopes with either pitch or roll inclinations. The analyses and the experiments are done with different Center-of-Mass (CoM) positions of the legs, which considerably influence the walking performance. It was found that, on up/down slopes, the stride of the thermal walker changes almost linearly with the slope angle. When the CoM was close to the center of the walker body, the walker walked backward on upward slopes. With CoM largely shifted backward, the walker could walk up slopes but did not walk down slopes well. On the other hand, when walking along a contour line of a slope, the stride decreased as the slope angle increased. The smaller leg swing distances would be caused by the change of leg swing time on such slopes.