Bilateral-wheeled inspection robot with flexible shock-absorbing suspensions for bridge cables

Stay cable inspections are crucial for the maintenance and safety of bridges, as their structural integrity directly impacts the overall stability of bridge systems. However, traditional inspection methods are labor-intensive, time-consuming, and expose workers to significant safety risks. To address these challenges, this paper presents a robotic system for the inspection of stay cables, with a lightweight body and a strong load-carrying capacity. The robot can move on bridge cables, replacing human workers in carrying out risky tasks and reducing inspection time with instruments such as cameras and non-destructive testing tools. The novel elastic suspension mechanisms are proposed in consideration of the surface conditions of the bridge cables. The designed robot is composed of V-shaped wheels driven by two motors on one side, joined by an adjustable frame. The elastic suspension constructed by 4 bar linkages improves the load capacity, stability, and obstacle negotiation performance of the robot. To avoid deviating risk and off-tracking, the anti-deflection mechanism is introduced. Laboratory experiments verified that the robot is capable of stable climbing under heavy load conditions and demonstrates strong obstacle-negotiation performance. It can carry a maximum effective payload of 11.1 kg and surmount obstacles up to 13 mm in height. The experimental results also demonstrate that for the elastic suspension mechanism, a suitable elastic coefficient is beneficial to improving the climbing performance of the robot. For practical applications, the field test results on cable-stayed bridges indicate that such a lightweight and high-performance system can improve the efficiency and stability of inspection operations and replace manual inspection with automated damage identification.