Reducing swing of model helicopter sling load using input shaping

Abstract

Helicopter sling-load operations are extremely useful, but they can also be dangerous. Excessive swinging of the load can degrade control, cause the payload to collide with obstacles, or allow the suspension cable to get tangled with objects. Suppressing load swing could increase safety and productivity. Input shaping is a control technique that has been used to suppress vibration of flexible machines, such as robots, satellites, and cranes. To investigate the use of input shaping on helicopters, a dynamic model is formed to characterize the translational response of a model helicopter and sling load to lateral control inputs. This translational model is used to simulate point-to-point movements with and without input shaping for a range of move distances. The input-shaped movements show greatly-reduced residual swing, with only a minor increase in move time. Data from an experimental trial using a model helicopter is presented.