Quadruped free gait generation for straight-line and circular trajectories

A method of free gait generation is proposed utilizing the primary/secondary gait for both straight line and circular body trajectories. The primary gait is a fixed sequence of leg transfers with modified leg-ends kinematic limits according to the presence of obstacles, while the secondary gait is a flexible gait which is generated to adjust the leg-end position. The primary gait is generated considering the following four constraints: stability constraint, kinematic constraint, sequential constraint and neighboring constraints. A generalized reference coordinate (GRC) system is introduced to describe the vehicle motion. Using the GRC system, all constraints and obstacle influences are expressed by only one set of equations despite the difference of motion mode. The efficiency of free gait generation is improved with the proposed method, and the trajectory of the vehicle body can be designed more naturally. Simulation results are given to demonstrate the efficiency of the proposed methodology.