An Aerostat Positioning System with Cable Control

The capabilities of a tri-tethered aerostat positioning system are investigated using simulations of a comprehensively validated dynamics model. The physical system studied consists of a payload supported by a helium filled aerostat and attached to three anchored ground tethers actuated using winches. Closed-loop control is achieved by feeding back the position of a payload located at the confluence point of the tethers. The dynamics model of the system is used to simulate the behavior of the closed-loop system. In a comparison of PID and optimal LQG control, a 50% improvement is achieved with the LQG controller. Both the LQG and PID feedback controllers were shown to benefit considerably from the addition of a feedforward control term that exploits measurements of the system’s main disturbance force.