Monitoring the Dynamics of a Helicopter Main Rotor With High-Speed Stereophotogrammetry

Stereophotogrammetry in conjunction with three-dimensional point tracking (3DPT) algorithms has proven to be a highly robust dynamic measurement technique on small, rotating bladed systems. This measurement technique can be scaled up to much larger systems and has several desirable features for helicopter and wind turbine structural health monitoring (SHM) applications that include: (1) it is noncontact and does not require the use of roll/slip rings for signal transmission; (2) the applied measurement targets negligibly affect the aerodynamics or structural mass/stiffness; and (3) position data can be collected on many hundreds of points over what is capable using conventional multichannel data acquisition (DAQ) systems. A field test was conducted in which operating data were collected on the main rotor of a helicopter in both grounded and hovering operating conditions. Part 1 of this work describes the experimental setup and DAQ process of the test performed and part 2 of this work presents some of the results including blade dynamics and extracted operating deflection shape information for the helicopter. The promising results presented in this work will serve as the foundation for the development of noncontacting SHM techniques that can be applied to large, rotating bladed structures while in operation.