Abstract: The wheel-legged biped robot is a typical ground-based mobile robot that can combine the high velocity and high efciency pertaining to wheeled motion and the strong, obstacle-crossing performance associated with legged motion. These robots have gradually exhibited satisfactory application potential in various harsh scenarios such as rubble rescue, military operations, and wilderness exploration. Wheel-legged biped robots are divided into four categories according to the open–close chain structure forms and operation task modes, and the latest technology research status is summarized in this paper. The hardware control system, control method, and application are analyzed, and the dynamic balance control for the two-wheel, biomimetic jumping control for the legs and whole-body control for integrating the wheels and legs are analyzed. In summary, it is observed that the current research exhibits problems, such as the insufcient application of novel materials and a rigid–fexible coupling design; the limited application of the advanced, intelligent control methods; the inadequate understanding of the bionic jumping mechanisms in robot legs; and the insufcient coordination ability of the multi-modal motion, which do not exhibit practical application for the wheel-legged biped robots. Finally, this study discusses the key research directions and development trends for the wheel-legged biped robots.

Key words: Wheel-legged biped robot , · Wheeled motion , · Legged motion , · Control strategy