Strategy Design and Experimental Validation of Moving Through Ladders for Hexapod Robot

Climbing ladders is an important capability for robots, enabling their deployment in diverse environments. However, existing research primarily concentrates on locomotion along ladders, neglecting the critical transitions between horizontal and vertical movements. To address this issue, our work proposes a comprehensive strategy for enabling hexapod robots to move through ladders. The process of moving through the ladder is divided into three phases, corresponding control methods are designed, and the boundary conditions of the key phases are discussed. Particularly, the gait and tripod gait are designed and implemented for the movement along the ladder, and a comparative analysis is conducted. For the ladder-to-ground phase, the torque support distribution of each leg is discussed, resulting the derivation of the constraint conditions during movement. As the result, the hexapod robot, RHex-T3, is upgraded by enhancing the torque output capability of its front limbs and reducing weight, and experiments are conducted to demonstrate the feasibility and successful performance of the proposed strategy. The robot can climb ladders with varying spacings, inclinations, and even vertical orientations.