Noise Cancellation of Helicopter Blade Deformations Measurement by Fiber Bragg Gratings

Abstract

The work presents data treatment methods aimed at eliminating the noise in the strain sensor data induced by vibrations of the helicopter blade in flight conditions. The methods can be applied in order to enhance the metrological performance of the helicopter weight estimation system based on the deformation measurement of the main rotor blades. The experimental setup included a composite plate fixed to the vibrating stand on the one end, with six fiber-optic strain sensors attached to its surface. In this work, the procedure of the optimal linear smoothing (POLS) and 3D-invariant methods were used to obtain monotone calibration curves for each detector, thereby making it possible to distinguish the increase of load applied to the free end of the plate with an increment of 10 g. The second method associated with 3D invariants took into account 13 quantitative parameters defined as the combination of different moments and their intercorrelations up to the fourth-order inclusive. These 13 parameters allowed the calculation of the 3D surface that can serve as a specific fingerprint, differentiating one set of initial data from another one. The combination of the two data treatment methods used in this work can be applied successfully in a wide variety of applications.

Dynamic Strain Measurement of Rotor Blades in Helicopter Flight Using Fiber Bragg Grating Sensor

“…A fiber Bragg grating (FBG) sensor, as an optical signal sensor, is essentially different from a resistance strain gauge, and it has a lot of advantages such as a long-term stability, a strong corrosion resistance, a small volume, a light weight, a high sensitivity, a strong resistance to electromagnetic interference, a broad transmission band, a large communication capacity, a low transmission loss, insulation, no electric spark, small leaks, and a strong confidentiality; it has been widely used in many fields, such as: a bridge motion system for measuring the vehicle parameters based on strain measurement using FBG sensors [ 1 ], an FBG sensing application in an arch dam model test [ 2 ], and the monitoring of a coal mine roadway roof based on FBG displacement sensors [ 3 ] in the field of civil engineering; fault detection of an FBG sensing system on airplanes [ 4 ], landing-gear load measurement using a wide-range FBG strain sensor [ 5 ], border detection application via temperature, strain, and pressure using FBG [ 6 ], and FBG sensors for aircraft wing-shape measurement [ 7 ] in the field of airplane engineering; FBG data treatment aimed at eliminating the noise in the strain sensor data induced by vibrations of the helicopter blade in flight conditions [ 8 ], helicopter bearing detection technology using FBG acoustic emission technology [ 9 ], and blade vibration load characteristic measurement using FBG by the authors [ 10 ] in the field of helicopter engineering; and FBG-based acoustic emission measurement [ 11 ] and a laser self-mixing FBG sensor for acoustic emission measurement [ 12 ] for structural health monitoring.…”