Jumping Motion Generation for Humanoid Robot Using Arm Swing Effectively and Changing in Foot Contact Status

Abstract

Human jumping involves not only lower limbs but also whole-body coordination. During jumping, the effect of sinking the center of mass for recoil and arm swing are significant, and they can cause changes in the jump height. However, upper body movements during jumping movements of humanoid robots have not been studied adequately. When jumping involves only the lower limbs, the burden on the lower limbs increases and it is difficult to jump as high as humans do. Also, if the sole is in contact with the ground during jumping movements, we cannot make good use of the ankle joint. Humans raise their heels during jumping movements, but there are few cases where humanoid robots achieve these movements. Therefore, we thought that jumping with recoil motion by the sinking, arm swing, and changing in foot contact status could result in a higher jump height higher than that possible with only lower limb movements. Hence, in this study, we generated jumping motion using sinking, arm swing and changing foot posture. First, a center of mass trajectory was generated by planning the entire jumping motion, and at the same time, the angular momentum was determined for stability. Next, the joint trajectory was calculated using these two parameters. At that time, arm trajectory and foot posture were specified in the null space. This generated a jumping motion considering arm swing. During simulations, this method provided a jump height almost four times the jump height that obtained without arm swing.