Precision-guided weapons have made a significant impact in recent armed conflicts. These weapons offer increased accuracy resulting in a greater percentage of enemy targets destroyed with less chance of collateral damage. Extending this precision-guidance capability to munitions fired from Navy ships, such as the Extended Range Guided Munition (ERGM - Figure 1-1), would allow precision strikes on enemy targets from a position over the horizon.

Inertial measurement units (IMUs) provide needed inertial guidance to the munition, complementing the Global Positioning System (GPS). Traditional inertial measurement unit approaches are too large, costly, and may not survive the high-g environment for certain classes of munitions. Microelectro-mechanical System (MEMS) based IMUs can provide the required accuracy and small size at an affordable cost while surviving the high-g environment of gun launches. In addition, MEMS IMUs offer a better lifetime performance profile compared with traditional mechanical approaches.

The EMPF has initiated a Navy ManTech program to provide the U.S. Navy with a cost-effective, gun-hardened IMU for precision-guided munitions (PGMs). The overall goals of this program are the following:

1) Demonstrate the viability of an alternative, low-cost ($150-$200) IMU accelerometer.

• Integration compatibility with SiIMU02 electronic
• Meet ERGM accelerometer functional requirements
• Survive high-gs required by near-term PGMs (>15,500gs)

2) Perform risk mitigation testing of the SiIMU02 in terms of:

• 20-year storage life capability of IMUs and MEMS
• Meeting ERGM environmental requirements

3) Identify risks and establish mitigation plans regarding the ERGM insertion readiness of the BAE SiIMU02 at a $2,500 IMU price.

4) Establish a Navy capability to assist DOD manufacturers with the evaluation of electronics packaging approaches and/or materials to be used in high-g hardware.

Previous U.S. Navy ManTech efforts have focused on lowering the manufacturing costs of the IMU. The main accomplishments of these efforts include the following:

• Detailed cost model generation showing path to $2,500/IMU at high-volume production
• Cost-reduction improvements to analog and digital circuit cards
• Establishment of a multiple-IMU capable rate table

One key enabler to achieving the desired $2,500/IMU for PGMs is to create a high-volume production demand. The highest volume, near-term, guided munition program is the U.S. Army’s XM-982 Excalibur. After a thorough quality evaluation, including numerous high-g tests, the U.S. Army has indicated that BAE Systems is a viable candidate supplier for near-term program needs.

In recent years, BAE Systems has provided the ERGM prime contractor, Raytheon, with MEMS IMU capability for ERGM baseline testing in the form of a custom-configured SiIMU01. The BAE unit has shown the ability to meet the ERGM form/fit/function requirements. This has included several successful high-g tests, which exposed the IMU to >10,000 gs.

BAE Systems has also supplied IMUs to the U.S. Army Excalibur program for evaluation. The BAE units have survived high-g tests and are considered finalists for Excalibur Low Rate Initial Production (LRIP). It is the desire of both the ERGM and Excalibur programs to have a minimum of two viable MEMS IMU suppliers in order to ensure price competition and reduce delivery risk. It is also advantageous to have the same IMU suppliers for multiple PGM programs in order to attain higher overall volumes and thus reduced IMU pricing.

It is currently expected that the SiIMU02 under development at BAE Systems (Figure 1-2) will be the product produced to satisfy lifetime demand of DOD PGM programs. Initial test reports indicate the SiIMU02 has shown the desired high-g survivability. The SiIMU02 is expected to exhibit a higher performance and a more versatile form/fit than the current SiIMU01, while retaining all the key advantages offered by the SiIMU01 model. This will make it available to a wider range of insertion opportunities, enabling mass production at a lower cost.

The High-G MEMS IMU Navy ManTech program will assist in producing a high-volume production SiIMU02 that is cost-effective and evaluate insertion-readiness per the ERGM program requirements. Savings obtained in this program can also impact other Navy programs such as the future Advanced Gun System (AGS). In addition, the SiIMU02 can be used for other DOD programs such as the Army’s XM-982 Excalibur and the Advanced Precision Kill Weapons System (APKWS). The efforts in high-g packaging along with a low-cost accelerometer at BAE would provide an option for the Extended Range Munition’s (ERM) Autonomous Naval Support Round (ANSR).