This study introduces a novel climbing strategy, reconfigurable parallel-type cable-driven climbing designed for long-span, large-scale bridge stay cable robotic applications, which has the potential to revolutionize the stay cable inspection and maintenance practice. The proposed methodology features the development of a Collaborative Climbing Robot Squad (CCRobot-S), which builds upon the design principles of the previous CCRobot series. In this study, CCRobot-S implements a parallel-type cable-driven manipulation design, allowing for reconfigurable kinematic morphology by its movable anchor bases and realizing the capacity of crossing over the stay cables for its flying platform. The collaborative robot squad design liberates the dimensions and scales of the robot's reachable workspace and moves the part of the robotic system that indeed needs to be moved, enhancing the working efficiency and climbing agility. This strategy also utilizes controllable adhesion instead of friction to interact with the bridge cable surface for the flying platform, realizing force multiplication for forceful manipulation. Toward bringing high efficiency and heavy-duty capacity, we propose the applicable climbing frameworks (zero-downtime climbing gait for cable inspection and spider-like climbing gait for cable maintenance) and the optimization frameworks (optimal anchor configuration for the movable anchor bases and optimal grasp arrangement for the flying gripper). This article includes the exploration of the design and climbing gaits of CCRobotS, the formulation of the CCRobot-S model, a comprehensive analysis of its workspace, and its climbing strategy and optimization. Extensive experiments have assessed the proposed climbing strategy's effectiveness and showcased CCRobot-S' capabilities.

This paper presents CCRobot-V, the fifth version of CCRobot, a cooperative serial multi-robot system for bridge cable inspection and maintenance that uses silkworm-like locomotion to climb the entire length of super-long stay cable at high speeds while carrying heavy inspection/maintenance equipment. CCRobot-V consists of one climbing precursor robot, one inspection/maintenance robot, several cable-carrying robots, and a power-tethered cable guiding system. The pre-cursor robot is the “head,” which leads the affiliated sub-robots along the bridge cable. Every sub-robot possesses a pair of self-locking palms. When a sub-robot grips on the bridge cable with its palms, it becomes a fixed anchor point that allows the adjacent sub-robots in front and back to use winches and steel wires to pull themselves upward. With this cooperative multi-robot system, cable inspection/maintenance tasks can be divided into several functional units, with each inspection/maintenance equipment installed separately on a customized sub-robot. Thus, CCRobot-V provides a complete mobile inspection/maintenance work line for a bridge cable. The experimental and field tests demonstrate CCRobot-V's high climbing speed, high payload capacity, and full-length cable moving capability. It has the potential application value for the actual bridge cable inspection/maintenance.

A Flying-type cable climbing robot, CCRobot-IV-F, is presented in this paper. It is a climbing precursor of the fourth version of CCRobot, designed to surpass the abilities of previous robots with high climbing speed and obstacle-crossing capability. CCRobot-IV-F weighs less than 10 kg and a no-load speed of up to 4.5 m/s, which significantly exceeds that of other climbing robots. A dynamic model integrated with a cable-fixed coordinate system is developed, and a cascaded controller designed for stabilizing hover and climb with grippers, when a Global Positioning System and magnetometer are unavailable, is shown to work reliably in practice. Experimental results show that CCRobot-IV-F significantly improves the locomotive performance of CCRobot-IV, exhibiting fast speed, good payload capacity, and excellent obstacle-crossing capability. Moreover, CCRobot-IV-F is applied to a cable-stayed bridge in the field.

This paper presents a novel Cable Climbing Robot CCRobot-III, which is the third version designed for bridge cable inspection tasks, aiming at surpassing previous versions in terms of climbing speed and payload capacity. Benefiting from Split-type Wire-driven design, CCRobot-III can climb along a 90-110mm diameter bridge cable in inchworm-like gait at a speed of up to 12m/min, and carrying more than 40kg payload at the same time. CCRobot-III consists of a climbing precursor and a main-body frame. The two parts are connected and driven by steel wires. The climbing precursor, acting as a mobile anchor, moves quickly on a bridge cable. The mainbody frame, acting as a mobile winch, carries payload and pulls itself to a certain position with steel wires. Both parts have one or two pairs of palm-based gripper, which is the key component for providing strong adhesion to support the robot climbing. Experimental results have shown that CCRobotIII possesses outstanding climbing performance, high payload capacity, and good adaptability to complex conditions of cable surface. Moreover, it has potential engineering applications on the cable-stayed bridge for fieldwork.

This project aims at developing a bio-inspired climbing robotic technology for cable inspection on the cable-stayed bridge. The design and implementation of a palm-based cable climbing robot: CCRobot-II with mass 25 kg, maximal payload 30kg and maximal length 1.1 m are described. CCRobot-II consists of several novel design features, including the palm-based gripping module, the alternating-sliding frame specialized for high-speed climbing, and the following wheels. With its carefully designed mechanism, climbing gait and trajectory algorithm, CCRobot-II is able to crawl along a bridge cable with a maximal speed 5.2 m/min. This speed has been hardly achieved by a existing climbing robot with such a large scale, and it is nearly the twice as the climbing speed of CCRobot-I which is designed previously. CCRobot-II also works effectively even if the bridge cable surface is attached with small obstacles. Experiments have been conducted, the results show that CCRobot-II has potential engineering applications on the cable-stayed bridge for fieldwork.