Miniaturization and sensor fusion of a measurement unit for a trailing bomb

This paper deals with possibility of increasing accuracy and long term stability of an inertial measurement unit based on MEMS sensors used in a trailing bomb probe. The probe uses an air speed sensor, an altimeter, angle of attack and angle of sideslip sensors, and a complete IMU composed of triads of MEMS gyroscopes, accelerometers and magnetometers appended with pressure and temperature sensors. While the pressure and temperature sensors are crucial for trailing probe application the IMU is used for the probe orientation estimation. Accuracy and long term stability of the aero-metrical sensors can be increased while complemented by positional angles measurement. This article describes a method for sensor error parameters determination by usage of stable values of other sensors in the measurement system. Main aim is to increase sensor´s accuracy and long term stability by data fusion from gyroscope triad sensors and a vector magnetometer. The algorithm will be used to determine positional angles in future. A positional angle computing was tested on data acquired by inertial measurement unit iNemo, a development kit from ST Microelectronics. The measurement system is described in this paper with a brief description of all of its components. The results obtained by the computational algorithm are discussed in this paper. While the present version of the probe measurement system is large the authors propose its miniaturized version where the COTS pressure sensor was replaced by a more precise and custom made pressure sensors. The actual test system and the proposed unit are designed to employ smart sensor functionalities, such as plug & play, self-testing and self-description, based on IEEE1451 group of standards.