A Passive Mechanism Reducing Cable Disturbance Torque on a Tethered Multicopter

Multicopters connected to the ground stations by cables are called tethered multicopters, and they have been widely used in emergency lighting, communications, etc. In a tethered multicopter, the cable inevitably generates tension. However, the acting point of the cable tension is always below the center of gravity of the multicopter, which creates a force arm for the cable tension. In some cases, the cable produces a large tension on the multicopter, which causes a large disturbance torque, even leading to a crash. To alleviate this problem, this article designs a passive ellipse-inspired mechanism to reduce the disturbance torque from the cable tension, which has a simple structure and is easy to install. The dynamics of the designed mechanism are modeled. To analyze the final state of the designed mechanism in any cable tension direction, the equilibrium states are solved, and the stability of these equilibrium states is discussed. Furthermore, the reason for the reduction of the disturbance torque is analyzed when the designed mechanism is stable. Theoretical analysis, simulations, and real-world experiments validate the effectiveness of this mechanism.