Motion decoupling design and kinematics analysis of a variable topology mechanical leg
CHENG Yuelin
LI Ruiqin
GUO Wenxiao
LI Hang
PAN Wuxing
Abstract：[Objective]To improve the terrain adaptability of wheel-legged mobile robots and simplify the control of driving and wheel-leg mode switching,a parallel variable topology mechanical leg with zero coupling and partial motion decoupling was proposed.[Methods]Firstly,a variable topology kinematic joint was designed based on the structure composition principles of variable topology mechanism.Secondly,a variable topology mechanical leg was designed and analyzed based on the position and orientation characteristics(POC)sets.Then,using the topological characteristic kinematics method,the symbolic position forward and inverse solutions of the mechanical leg were solved,and its workspace and singularity were analyzed.Finally,a quadruped robot was constructed using the variable topology mechanical legs,and the gait planning was carried out on the steep slope and gully terrain to test its obstacle-crossing capability.[Results]The variable topology mechanical leg has two motion modes of wheel and leg.The POC set in the leg mode is 2R1T,and the POC set in the wheel mode is 3T1R.The switching of the two motion modes based on the variable topology kinematic joint reduces the time required for mode switching and is simple to control.Obstacle-crossing tests have shown that the variable topology mechanical leg has strong passing capability for the com-plex terrain such as steep slope and gully.
Keywords：Mechanical legPOC setVariable topologyMotion decouplingSingular configuration
Publication Date：2025-11-15
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：10( 70-79 )