THE KEY FACTORS FOR A ONE-LEGGED ROBOT TO KEEP BALANCE WHEN HOPPING IN PLACE

摘要

In order to study the key factors that influence the balance of a hopping one-legged robot, we decompose the hopping balance model into two parts: leg swing control in flight phase and stability control in stance. During flight phase, since the horizontal velocity is not easy to measure by sensors and might cause cumulative error and time delay, we use body attitude and angular velocity as approximate input parameters to replace horizontal velocity in leg swing algorithm. In the experiments of stance phase, we discover the close relation between duty factor and spring rate as well as state transition threshold of pneumatic cylinder on the leg. We combine the two experiments and preliminary implemented the balance of one-legged robot hopping in place. The experiments demonstrated that body attitude and angle velocity in flight phase and duty factor in stance phase are the key factors for balance. Comparing to works made by Raibert[2] in balance controlling under high translation speed, our work provides references to study balance of robot while hopping under low horizontal velocity.