A Contact-Maintaining Track Width Regulation Framework for Wheel-Legged Robots

When wheel-legged robots encounter obstacles such as collapsed deep pits or rocks, or need to avoid crushing critical objects, conventional approaches adjust the track width through leg-lifting maneuvers, which may compromise robot balance, reduce load capacity, and affect other performance metrics of robots. To simultaneously address track width regulation under such scenarios and mitigate the negative impacts of conventional approaches, this article proposes a contact-maintaining track width regulation (CTWR) framework. The framework integrates online posture-wheel coupled trajectory optimization with deformation-based whole-body control, enabling lateral track width adjustment without lifting legs. Compared to mainstream leg-lifting methods, the CTWR framework demonstrates well performance in effectively regulating track width while reducing maximum joint torque and peak power output. Experimental validation on real wheel-legged robots confirms not only the framework’s efficacy in crossing obstacles through track width adaptation, but also its contribution to enriching locomotion modes for wheel-legged robots.