ABERDEEN PROVING GROUND, Md. -- For the past decade members of the Army's research community have worked to develop models of an active protection system with multiple configurations. The goal is to eventually field APS variants on Army vehicles.

Greg Bradley, a member of the U. S. Army Research Laboratory's Survivability/Lethality Analysis Directorate's Advanced Systems and Lethality Branch, explained, "The number one reason [APS is important] is because these threats are everywhere and they are ubiquitous and pretty powerful. It has become very difficult to put enough armor on the vehicles without making the weight incredible."

Regardless of how much safer a Soldier or platform would be with additional armor, there is a physical limit to the weight that can be added to vehicles and Soldiers. With every additional pound the vehicle or Soldier is sacrificing key attributes such as agility and speed. It is important to find a design that optimizes survivability without impeding the Soldier's or platform's performance.

Teams at SLAD are working with Aviation and Missile Research, Development and Engineering Center, Gleason Research Associates, Inc., and ARL's Weapons and Materials Research Directorate to build models to incorporate into AMRDEC simulations. These models allow analysts to run various target-threat scenarios in an effort to determine the most effective configurations and potential uses of an APS.

Bradley explains, "The real value is running the models in the system simulation--the idea is to be able to try different components in the system." Because the system runs in a sequence, there are variables that become evident only when all of the modeled elements are combined in the simulation.

Accurately modeling an APS requires capturing a sequence of complex events from end to end. The sidebar below explains the sequence.

In a generalized scenario, these six steps would have to occur in less than a few seconds. The sequence must be accurately replicated in the model, allowing variables to be manipulated.

1. An enemy fires at the vehicle from some distance away.
2. The APS cueing sensor detects that a shot may have been fired.
3. The cueing sensor cues the radar to scan the detected area to read what is happening.
4. The radar slews around and collects data, determines the threat, and sends continuous data through tracking filters.
5. The radar uses the tracking filters to develop a fire-control solution (essentially instructions for when and where to fire an interceptor).
6. An interceptor is fired, flies out, and detonates at a prescribed location to defeat the threat.

The interceptor's interaction with the incoming threat often results in residual threats; these have been the focus of modeling efforts for Bradley and members of SLAD's Ballistics and NBC Division. Lon Anderson, a member of SLAD's Information and Electronic Protection Division, has focused his efforts on the front end of the scenario: building detailed models of specific elements of the cueing sensors, radars, and the fire-control solution.

Anderson explained the depth of this endeavor, "SLAD recognized ten years ago, when we jumped into this with both feet, that we can't do it on our own. So, this diverse group of technical experts within RDECOM [U.S. Army Research, Development and Engineering Command] has worked to develop a family of simulations, which have required contributions from just about every RDECOM element."

Today SLAD employees are partnering across the RDECOM to integrate an APS into a vehicle's design. SLAD's role has been to develop models for the two ends of the APS sequence. According to Anderson, "With some rare exceptions we [SLAD] don't build the components or the systems. Other areas of the government are focused on building the system."

Yet another aspect of this large program involves system-level demonstrations of various APSs, foreign and domestic. "These [demonstrations] help to develop generic models to improve existing models," explained Janet Shindell, a member of the Advanced Systems and Lethality Branch who has been heavily involved in the live-fire tests.

Bradley, Anderson, and Shindell each focus on distinct aspects of this project. Because of the complexity of today's battlefield, they have partnered throughout this process to ensure that the models SLAD develops are effective and sound.

All three SLAD analysts agree that the biggest goal of this project is to help the Army successfully field an APS by working within the community of developers. To achieve this goal those involved must continue to work through the systems' complexities and further develop the APS to make it fully adaptable. When this is accomplished the APS will be a worthwhile, life-saving system.

[From the December 2012 edition of the SLAD Bulletin]