Design and analysis of a novel walking vehicle based on leg mechanism with variable topologies

In order to improve the adaptability of one-degree-of-freedom leg mechanism to unknown terrains while maintaining its control simplicity, energy efficiency and integral rigidity, a novel close-chain mechanism with variable topological structures is proposed to act as a single leg to generate different gaits. The design process of the closed kinematic chain is completed by integrating two types of mechanical joints. Besides, the kinematics of the single leg under two modes is analyzed using vector loop method, and the particular structure of the leg mechanism is designed with optimized parameters. The topological states are represented with graphs and a matrix. Moreover, the whole close-chain legged unit and the walking vehicle are developed and constructed. In particular, to evaluate the crossing ability, this paper proposes the obstacle-surmounting probability. A series of dynamic walking simulations is conducted and analyzed to support the obstacle-surmounting capability and mobility comparison. Legged units are fabricated to verify the theoretical analysis, and walking experiments with a multi-legged vehicle are performed to testify the prototype performance.