Rapid Automatic Slung Load Operations with Unmanned Helicopters

Abstract

Slung load operations often involve following conservative flight paths to prevent unwanted swing of the load. However, doing so often limits the maneuvering capability of the system and increases the time to complete trajectories. This work investigates methods to rapidly move a slung load with a helicopter with the intent to deliver it quickly and precisely to a fixed point. Inspired by prior work utilizing differential flatness, which is a property of certain systems that allow for advantageous controllers to be developed for nonlinear systems, the controller developed does not require instrumentation of the load or the ability to estimate the state of the load but does not preclude it. A feedforward and feedback controller was developed that modifies the helicopter commands based on the desired load path. The controller is simplified by neglecting selected higher order terms and modeling the load as a point-mass. An adaptive dynamic inversion controller is used to control the helicopter. A fixed downward-facing camera is used to provide estimates of load position for the feedback controller. Simulation and flight-test results are shown using a Yamaha R-MAX helicopter to validate the proposed method.