Compact High-Range Yaw Joint Design for Articulated Robots in Confined and Unstructured Environments

This paper presents the functional design of Brush.Q, an articulated ground mobile robot for operation in unstructured environments, with a primary focus on the design of its yaw joint. The robot is composed of four driving modules, each equipped with two independently actuated multi-spoke wheel-legs with compliant geometry, connected through three joint units. Each joint provides three degrees of freedom, arranged in a pitch–yaw–pitch configuration, allowing enhanced adaptability to complex and confined spaces. The proposed yaw joint is based on a rolling-contact anti-parallelogram mechanism that achieves a large range of motion and a small turning radius. A first prototype is presented and experimentally evaluated through preliminary tests to assess its functionality.