Design of an automatic load positioning system for hoist operations

The operation of a helicopter with an externally slung load is highly demanding for the flight crew. Without having a direct view on the load, the pilot needs assistance by a crew member for load handling, e.g., load positioning. During helicopter hoist operations (HHO), the hoist operator gives instructions to the pilot and stabilizes the load motion. An automatic load positioning system for HHO is designed with the aim to reduce the workload of the flight crew and to improve the load handling performance. The control system consists of a multiloop architecture that is designed using multi-objective optimization. The system was designed to achieve best performance in load positioning for the entire cable length range of the rescue hoist. Load positioning performance is a function of the cable length; faster automatic load positioning can be achieved with the shorter cable lengths. This paper describes the overall design process covering the tools, the control law architecture and optimization, and the validation using DLR's simulator