The obstacle-negotiation capability of rod-climbing robots and the improved mechanism design

To detect internal steel wire fractures in the cylindrical cable of cable-stayed or suspension bridges automatically in hazardous environments instead of workers, a trilateral clamping-wheeled, rod-climbing robot is designed in this study. In line with this objective, this study also introduces the climbing principle and mechanical structure of this robot (Model-1) and analyzes the static dynamic characteristics of this mechanism. Furthermore, it establishes the mathematical models of the moving wheels during obstacle negotiation. This study also analyzes the relationships of main driving force and resistance with obstacle height to determine the obstacle-negotiation capability of the robot and the two main parameters that influence its obstacle negotiation performance, namely, wheel radius and positive pressure. The Model-1 structure was updated to a new climbing mechanism (Model-2) based on analysis results. Furthermore, the optimal angles of the upper and lower supporting arms were obtained by building the static model of the new mechanism. Finally, Model-2 is superior to Model-1 in terms of obstacle-negotiation capability and satisfies the requirements for suspended cable detection.