Modeling and input shaping control of a micro coaxial radio-controlled helicopter carrying a suspended load

Helicopters are often used to transport supplies and equipment to hard-to-reach areas. When a load is carried via suspension cables below a helicopter, the load oscillates in response to helicopter motion and external disturbances, such as wind. This oscillation is dangerous and adversely affects control of the helicopter, especially when carrying heavy loads. To provide better control over the helicopter, one approach is to suppress the load swing dynamics using a command-filtering method called input shaping. This approach does not require real-time measurement or estimation of the load states. A simple model of a helicopter carrying a suspended load is developed and experimentally verified on a micro coaxial radio-controlled helicopter. In addition, the effectiveness of input shaping at eliminating suspended load oscillation is demonstrated on the helicopter. The proposed model may assist with the design of input-shaping controllers for a wide array of helicopters carrying suspended loads.