In this paper, a slip-limiting controller for redundant line-suspended robots is presented. This kind of robot is usually equipped with v-shaped wheels, which brings uncertainty about the effective wheel radius, particularly when crossing obstacles. The proposed algorithm is able to estimate and limit wheel slippage in the presence of such uncertainty, relying only on wheel angular velocity measurements. Slip limitation occurs in the control allocation algorithm and hence is decoupled from the high-level velocity controller, allowing a broad applicability in centralized control approaches. Experimental results on Line Ranger show that it effectively reduces wheel slippage compared to traditional centralized control while being more energy efficient than traditional decentralized control approaches.

Robotic platforms dedicated to powerline inspection are often complex to operate, take several minutes to cross any obstacle, and must be operated by highly trained specialists. To further its goal of massive inspection of its power grid, Hydro-Québec developed an innovative robot that is simple to operate and can be used directly by line maintenance technicians. LineRanger was developed following the field deployment of LineROVer and LineScout but aims at surpassing them in terms of inspection efficiency. With an ingenious and passive obstacle-crossing system, this new robot allows large-scale inspection of bundled-type powerlines, since the obstacle crossing time is considerably reduced. In this paper, details on the robot's key features are presented along with its mathematical analysis, which guarantees its stability on flexible bundles and directly influenced the design. Finally, the LineRanger prototype is presented, with insights about its first field deployments.