On the optimal energy efficiency of the multi-rotor UAVs of an aerial work platform based on an aerial cable towed robot

Aerial Cable Towed Robots (ACTRs) have been proposed by several researchers for aerial manipulation in recent years. However, the low energy efficiency of the multi-rotor Unmanned Aerial Vehicles (UAVs) of ACTRs prevents ACTR-based aerial work platforms for aerial manipulation from a wider range of applications. To provide a guideline for the design of an ACTR-based aerial work platform with an improved energy efficiency of UAVs, this paper investigates the effects of the position of UAVs, the tension distribution of cables driven by UAVs, and the number of UAVs on the energy efficiency of the UAVs of an ACTR-based aerial work platform. A power consumption model is developed for UAVs, assuming that the UAVs are towing cables to stably generate a certain resultant wrench or force on the moving platform. Based on the developed power consumption model, the position of UAVs and the tension distribution of cables to obtain the minimum total power consumption of UAVs are determined. Then, this paper studies whether an additional UAV will inevitably increase the minimum total power consumption of UAVs. The achievements of the energy efficiency of UAVs in theory are explained in case studies.