Novel Energy Transfer Mechanism in a Running Quadruped Robot with One Actuator per Leg

In this work we develop a novel method, or mechanism, of energy transfer in a quadruped running robot. The robot possesses only one actuator per leg, for lower weight and greater power autonomy. The developed mechanism ensures correct dispersion of energy to the actuated and the unactuated degrees of freedom of the robot for stable running. In the mechanism design, we address the added problem of running on inclined ground. In conjunction with a pitch control method, the energy transfer mechanism forms a complete control algorithm. Due to the novel dynamics-based design of the mechanism, it allows the arbitrary setting of the motion forward speed and apex height. Further, it may be applied for different robot physical parameters and ground inclines, without extensive controller tuning. This has not been previously possible using only one actuator per leg. Simulations of a detailed three-dimensional model of the robot demonstrate the mechanism on two different robots. The simulations take into account many real-world characteristics, including realistic leg models, energy loss due to feet collisions, foot-ground friction and energy losses in the joints. Results demonstrate that inclines of up to 20 degrees are properly negotiated. (C) Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2010