Six Degree Freedom Optical Fiber Accelerometer

Abstract

Linear accelerations measurements are needed in many applications, as industry, military, aircrafts, space navigation, robotics and others. Actually, the most usual solutions to measure linear accelerations are three piezoelectric sensors used in orthogonal mounting, or MEM’s sensors chips. Angular accelerations also are interesting to control and stabilize structures, like satellites and servo motors. It is possible to measure angular accelerations in two ways: direct measurement (using special sensors), or indirect measurements (obtaining acceleration of the angular velocity information) [1]. This work intends to present the structural and optical requirements of a six degree freedom opto-mechanical accelerometer based on fiber Bragg grating (FBG). With this sensor, it will be possible the direct measurement of three axial accelerations, and of three angular accelerations, with unlimited rotation angle, using one single proof mass. The FBG’s are used as strain sensors and sustaining elements of the proof mass in the structure. Simulations have demonstrated that cross influences of 10 parts per million at worst case are possible. This kind of accelerometer may be used in navigation control, structural monitoring, satellite stabilization, guidance control and harsh environments, for example. The project requirements include the wavelength of FBG’s, pre-strain and length of active segment of optical fibers, dimensions, material and structure of inertial proof mass and position of the fibers in the sustaining structure