DESIGN OF A LOW-COST ORIENTATION MEASUREMENT UNIT FOR MILITARY VEHICLES

The OMU (orientation measurement unit), a combination of inertial (accelerometer, gyroscope), magnetometer and GPS/GNSS sensors, can play a significant role in the stabilization, orientation, navigation and munitions guidance applications performed in ground-based military vehicles. The raw data measured by the OMU’s sensor array includes angular rate, acceleration, magnetic field strength as well as position. By blending these sensor measurements with the use of software algorithms (a.k.a. sensor fusion), the data can be transformed into orientation data (pitch, roll & yaw), commonly referred to as Euler Angles. OMUs have a wide range of price that depends on the quality of its individual device sensors, environmental packaging, standards met and the sophistication of the device firmware used to filter, correct and smooth the inertial inputs used in the computation of application output data. In the ground-based military vehicle industry, applications supported by the OMU could range from a simple rollover warning/prevention system to a sophisticated slew-to-cue director. The success of these applications depends greatly on the OMU’s individual sensor quality/grade, which are tightly coupled with the sensor’s technology type, cost and size. This paper focuses on how the OMU can be designed to achieve/approach the operational performance of the more costly and well-known Strategic/Navigation –grade military navigation sensor product offerings, for a fraction of the price. The OMU’s expected applications, operational objectives and the resulting performance requirements, which lead to component selection, will be explained. The paper will also highlight the results of the effort to develop an OMU and provide a discussion of recent work related to device testing and integration.