Trends in INS Development — A Mini-Panel Presentation and Discussion

Abstract

Many advances have been made in the past 15–20 years on the application of inertial navigation systems (INSs) to the fields of geodesy, surveying, and remote sensing. This paper addresses those applications and experiences gained where the INS was used in a direct measurement role. However, INSs have also been used to stabilize or provide motion compensation data for other primary sensors, such as radars, lasers, and other electro-optical devices. This aspect is also touched upon.

The gains made during this period were particularly impressive in the performance area. Also included was the flexibility with which the same basic equipment could be adapted, with mostly software and procedural changes, to a wide variety of uses. After summarizing the initial experiences, which used mostly gimballed inertial systems, the paper moves into the era of strapdown INSs, during the mid-to-late 1980’s. An example of one of these systems, the U.S. Army’s Modular Azimuth Position System (MAPS) is described, along with summaries of very extensive, open loop survey and positioning tests.

Honeywell started development of its H-726 Modular Azimuth Position System (MAPS) in September 1984. This system represented a major advancement in the field of inertial pointing and positioning systems for combat vehicles, with the introduction of the rugged, highly accurate, and extremely reliable laser gyro.

The Dynamic Reference Unit (DRU), the heart of the MAPS, is an all-axis strap-down, inertial navigation system, which has been adapted for land navigation, positioning and pointing. Over the last five years, the H-726 has been thoroughly evaluated and field tested over a wide variety of conditions in the US, UK, FRG, Sweden, Norway, Switzerland, France and Japan. Applications ranged from positioning and pointing of self-propelled howitzers to steering coal mining machines, and artillery battery surveying. At this writing, Production contracts are underway to supply the H-726 MAPS to the US, UK and Swedish Armies.

But what does the future hold? In the very near term, there is the potential for applying RLG strapdown INS technology to closed loop surveying and positioning for improved accuracies. Several levels of performance capability are available with different grades of existing gyros and accelerometers, as well as various system mechanization and software improvements. The combination of INS and GPS systems, in either stand alone or fully integrated and embedded (packaged together) ways, is also achievable.

Later in the 1990’s, it will be possible to reduce the size, weight, and power of strapdown RLG INSs without sacrificing performance, compared to MAPS systems capabilities. Other inertial sensor and electronics technologies may also become available. All of these possibilities are discussed in the paper.