A balance control strategy of a walking biped robot in an externally applied force

In this paper, we present a balance control strategy for a walking biped robot in an unexpected external applied force. We assume that a sudden lateral and longitudinal force could be applied at the center of the pelvis of the biped robot during walking with a walking trajectory which is predesigned in advance by considering the energy-efficiency. With this situation, an balance control strategy is investigated and suggested. The balance control strategy is divided into four successive actions. Firstly, the robot should be controlled for the ZMP(Zero Moment Point) to move to the center of its sole. Secondly, the robot moves its swing leg to make the height of the sole of its swing leg lower. Thirdly, the swing leg of robot is stretched. Fourthly, the stance leg is contracted to make the robot in the double support phase. To verify the suggested strategy, computer simulation is performed.