Static Workspace Optimization of Aerial Cable Towed Robots With Land-Fixed Winches

This article focuses on the static workspace (SW) of aerial cable towed robots (ACTRs) with land-fixed winches and provides an optimization approach to maximize the size of such a workspace. In the structure of the studied robots, land-fixed winches beside the ACTRs, actuated by unmanned aerial vehicles (UAVs), are used to manipulate a platform to reach high-altitude poses and balance platform's interaction force/moment in such poses. Capability of UAVs in choosing and holding different positions and orientations enables the studied robots to adapt their available net wrench set (AW) to various required net wrench sets. In order to find the SW of ACTRs with land-fixed winches, at first, AW of a generic robot for a given arrangement of UAVs is developed analytically. Then, a geometrical approach is provided to find all collision-free arrangements of the UAVs. Based on that, a performance index is derived and optimized to find an optimal collision-free arrangement of the UAVs, which maximizes the magnitude of the force that can be balanced by the platform in any arbitrary direction. Finally, the application of the proposed optimization approach in size maximization of the SW is shown in an example.