Research Progress and Challenges of Multi-lift Rotorcraft Systems

Multi-lift rotorcraft systems consist of multiple rotorcrafts, cables, and a single suspended load, which are a new kind of mechatronic systems with the ability of aerial manipulation. The systems are excellent because of their good flexibility, the ability of reaching remote places, convenience transportation ability and excellent loadability. Multi-lift rotorcraft systems are wildly applied to engineering practice, but there are many problems in terms of their modelling and control. Rotorcraft systems are complex, underactuated and nonlinear. Because of the existence of cables and the load, multi-lift rotorcraft systems become more and more coupling, underactuated and nonlinear. To give a review of the research progress and challenges of multi-lift rotorcraft systems, firstly, we introduce the common configurations, and analyze their advantages and disadvantages. Secondly, we outline the hot issues such as dynamic modeling, coordinated control, and experiments of multi-lift rotorcraft systems. Finally, we analyse the key scientific problems, as well as potential application fields of multi-lift rotorcraft systems, and point out the future work.