Developing a Novel Contactless Sensor for Helicopter Rotor State Measurements

The present contribution concerns the development of an innovative measurement system for rotorcraft applications. This system aims at the real-time acquisition of the motion of a rotor blade in flight, for applications in emitted noise prediction and monitoring, and in rotor state feedback control augmentation. A structured approach to the system design, implementation and testing has been pursued starting from a survey of applicable technologies. Contactless solutions were targeted, in view of maximum compatibility with a wide class of vehicles. A first development phase saw the selection of three concepts, all conceived to be mounted on the rotor head and pointing the blade root area, based either on 2-D laser transducers or on vision-based sensors. These were implemented in full scale and laboratory tested to choose the most promising for definitive development. The final solution, a stereoscopic vision-based measurement system, was brought to maturity through further development and laboratory testing, up to fully integration on board a prototype helicopter for ground and flight testing. We detail the various stages in this process, motivating the choices made and illustrating the results in terms of measurement accuracy.