Load monitoring of a helicopter inceptor through efficient FBG sensors placement

Abstract The implementation of fly-by-wire technologies on rotorcraft requires the knowledge of the loads exerted by the pilot on the command chain during the flight; however, it is not easy to retrieve such information. In this work, a novel composite sensorized helicopter inceptor is developed aimed at monitoring the loads applied by the pilot during the flight for the entire helicopter lifecycle. The inceptor is produced using a soluble mandrel, and the connection elements are produced in polymeric material, allowing the connection of the optical fiber carrying the fiber Bragg grating (FBG) sensors to the interrogation system. Two prototypes of inceptor are manufactured, the first is produced with the aim to calibrate the Finite Element (FE) model of the component. Then the model is exploited to perform a sensor placement optimization based on the minimization of the condition number of the system using a Genetic Algorithm. The second prototype is produced positioning the FBG sensors according to the output of the optimization. Results show that a satisfactory load identification capability is obtained using only two sensors positioned according to the optimization technique. A comparison is also performed using the first prototype equipped with four strain gauges positioned using qualitative criteria: results show that a better load identification quality is obtained with only two sensors positioned according to the placement optimization technique. This work demonstrates the feasibility of a composite sensorized helicopter inceptor, characterized by a complex geometry, capable to provide satisfactory load identification quality with a limited number of sensors.