A Bipedal Locomotion Planning Based on Virtual Linear Inverted Pendulum Mode

In this paper, a bipedal locomotion planning based on virtual linear inverted pendulum mode (VLIPM) is proposed. In conventional methods, the desired center of gravity (COG) position and velocity are achieved by modifying the foot placement. In this research, the desired COG position and velocity are achieved while the desired foot placement is also realized. In the proposed method, the virtual modified foot placement and trajectory planning are calculated separately. VLIPM is applied to the calculation of the virtual modified foot placement. By using virtual supporting point (VSP), the difference between the virtual modified and desired foot placements is compensated. In the result, the desired foot placement is achieved as if the foot placement is in the virtual modified foot placement. Trajectory planning is applied to LIPM with VSP and 5-D polynomial. The boundary conditions of the polynomial are set to the desired COG position and velocity. In the result, the desired COG position and velocity are also obtained. Differences of the motion by different models are compensated by matching the boundary conditions of different models. By applying different models in the calculations of the foot placement and trajectory planning, the desired robot motion is realized. The walking stability of the proposed method is equivalent to that of the conventional method. The effectiveness of the proposed method is confirmed by a simulation and an experiment.