A Low Cost Solution to Provide Accurate Inertial Sensing for Flight Test Requirements

摘要

This paper describes the development of a modern, portable inertial instrumentation suite for flight test, from which a complete set of accurate aircraft inertial state parameters can be computed. The goal is to develop a strapdown inertial navigation system of relatively low cost and size compared to a medium accuracy ring laser gyro system such as the Litton LTN-90-100 IRS. The proposed system is based on an LN-200 IMU integrated with a NovAtel DGPS receiver. It will employ in-house developed strapdown navigation software, along with an INS/DGPS Kalman filter that corrects strapdown inertial errors in real time. Only the six primary IMU parameters (i.e., three linear accelerations and three angular rates) and barometric height are needed, together with DGPS-based position and (optionally) velocity data. From these digitized quantities, high quality inertial state parameters (i.e., position, velocity, Euler angles, angular rates and linear accelerations) can be reconstructed at a high data rate (e.g., 64 Hz or higher) for the entire flight. In many cases, having an optimal real-time strapdown inertial sensing capability is not essential; and the raw IMU/DGPS data can be optimally integrated postflight. using a so-called Kalman filter-smoother, in order to reconstruct an accurate aircraft inertial state time history 'after the fact'.