Improving Navigation Safety of an Omni-Directional Wall-Climbing Robot via Traction and Friction Control

Climbing on vertical concrete structures like bridge pylons or dams is still a great challenge for autonomous robots. This paper presents the traction- and friction control system of the wheel-driven wall-climbing robot CROMSCI and its impact on navigation safety. This robot applies negative pressure adhesion and driven wheels for propulsion. The main challenge is to produce sufficient high forces for carrying and accelerating the robot contrarily to gravity which is inhibited by different factors. Slippery of the wheels e.g. must be minimized due to abrasion and uncontrollable movements of the robotic system. This is done by measuring upcoming forces and taking them into account for a traction control system. Another problem may occur because of shear forces between the wheels lowering the transferable forces in rolling direction. Furthermore, also the seals influence robot locomotion due to a certain driving resistance. This paper will present these control elements and prove their functionality and impact on driving safety via experimental results.