Research on Kinematic Modeling and Gait Planning of a Hexapod Bionic Robot

Abstract

Aiming at unstructured scenarios with high terrain adaptability requirements such as field exploration and mountain operations, this paper proposes a retractable hexapod bionic robot scheme integrating a turtle-shell arched body and bending-type modular legs. The body adopts a three-layer assembled arched shell structure, drawing on the biomechanical characteristics of a turtle shell to disperse impact loads and enhance overall protective capability. The leg adopts a three-segment serial RRR configuration, with the outer leg having a fixed 36° inward bending angle to optimize foot-end force and obstacle-surmounting performance. Based on the D-H parameter method, a four-segment kinematic model of a single leg is established, and analytical solutions for forward and inverse kinematics are derived. The tripod gait timing is planned, the swing-phase foot trajectory is generated using cycloid equations, and a quintic polynomial scaling factor is introduced to achieve smooth start-stop transitions. A dual verification platform combining MATLAB theoretical simulation and Simulink 3D physical simulation is built, and cross-validation is carried out for three motion modes: forward walking, lateral movement, and in-situ rotation. The results show that the robot's steady-state forward speed is 40 mm/s, and the lateral cruising speed is 30 mm/s; the maximum foot-end position deviation between the two platforms is less than 0.5 mm, and the joint angle deviation is less than 0.1°, verifying the rationality of the structural design and the accuracy of the kinematic model.