John Weston

Fundamental principles and historical developments of inertial navigation

This chapter presents the historical development of inertial navigation and the basic concept of inertial navigation are outlined here with the aid of some simple examples.

Testing, calibration and compensation

This chapter outlined the evaluation testing, calibration of inertial sensors. The evaluation testing of inertial sensors is required to establish their suitability for a given application, that is, to ensure that they satisfy all the performance requirements of that application. The testing and calibration methods need to reflect the type of application and also, but very importantly, the environment in which the sensors and systems are to operate. It is crucial to establish that the sensors not only survive and operate reliably whilst being subjected to the vibrations, shocks and accelerations induced by the host vehicle, but also have sufficient endurance and resistance to survive the testing and calibration procedures.

Appendix D: Comparison of GPS and GLONASS satellite navigation systems

There are currently two satellite-based navigation systems deployed, the American controlled system known as GPS or Navstar and the Russian system GLONASS. There are a number of similarities between the two systems, such as the constellations consist of up to 24 satellites, although the configuration within each constellation is somewhat different. There are several other similarities between the two systems, but the characteristics of the two systems are sufficiently different to affect their operation and world coverage. The similarities and complementary nature of the differences in coverage lead to the possibility of using the systems together in an integrated system to enhance navigation performance. In this appendix, these satellite navigation systems were compared.

Alternative applications of IN sensors and systems

The range of applications which make use of inertial sensor technology is extremely broad, and is expanding rapidly, as illustrated by the examples given in this chapter. In designing systems for these varied roles, it is essential to consider the full context of the application, taking careful account of issues such as dynamic measurement range and the full range of environmental factors that may have a major impact on the design. In many of these new or novel applications the catalyst for their development has been the availability of low-cost miniature inertial sensors that offer high reliability and require little or no maintenance. In general, these devices are rugged so that they can be used in relatively hostile environments although, quite often, the measurement accuracy is mediocre. However, the quality of the sensor performance has proved to be well matched to the fundamental requirement, that is, only an indication of angular rate was required to fulfil the task. The development of integrated navigation techniques, particularly with IN sensors and satellite-based navigation systems, has led to devices that provide accurate navigational aids at a low price. This approach has seen the integrated navigation systems and devices displace high-performance IN systems from some traditional applications, a trend that is likely to continue.