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SSC-Natick Press Release

U.S. Army Soldier Systems Center-Natick
Public Affairs Office
Kansas Street
Natick, MA 01760-5012

Contact: Chief, Public Affairs Office
(508) 233-5340
amssb-opa@natick.army.mil

Date: March 16, 2004
No: 04-08

Manikin returns to thermal testing

NATICK, Mass. -- Uncle Wiggly, the 20-year-old articulated thermal manikin at the U.S. Army Research Institute of Environmental Medicine (USARIEM), has new life after a major component upgrade during the past year was completed in February.

The manikin's original copper-plated shell, cast aluminum joints, heaters and sensors remain, but a thermal control system consisting of signal conditioning, heater drivers and computer software, and a computer-controlled sweating system were installed by Measurement Technology Northwest in Seattle, Wash., into the existing body to create a product unlike any other.

"It's really amazing. You don't realize it until you see (other thermal manikins)," said Julio Gonzalez, a research scientist in USARIEM's Biophysics and Biomedical Modeling Division at the U.S. Army Soldier Systems Center in Natick, Mass. "With the unique way it's built and operates, I don't think they'll make another one like this."

Researchers have used thermal manikins to measure thermal and water vapor resistance values of clothing since the 1940s to help improve functional performance and thermal comfort. The values are also incorporated into practical human performance models by the division to predict work/rest cycles, maximum work times and water consumption requirements, according to Gonzalez.

"It all started as a way to predict Soldier performance in the field," he said. "The modeling results then can tell how long personnel can safely operate in certain environmental conditions."

USARIEM started using Uncle Wiggly in 1984 during a push in the 1980s by the Army to completely redesign military clothing systems using a variety of new technologies and materials, such as Gore-Tex and Thinsulate.

The manikin has 19 individual heating zones and swings its arms and legs to simulate walking at speeds up to 3 mph. Testing is conducted in its own chamber controlled for temperature, humidity and wind speed provided by a fan.

Still functional, the original manikin had become increasingly difficult to operate with slow computer processing power and parts that were wearing out. All data was printed out and then entered by hand into a computer to calculate wet and dry insulation values of various prototype military uniform ensembles. If testing wasn't closely monitored, previous measurements could be lost, and results were difficult to repeat.

"Now we're able to collect data in real time on a Windows-based computer, and all the data is saved automatically. I can open the file later to analyze the numbers," Gonzalez said.

Measuring dry insulation values was demanding, but measuring water vapor transfer through the clothing was worse.

Before the upgrades, he had to simulate sweating of the manikin by applying water to an all-cotton layer "artificial skin" without getting the actual test clothing wet.

"You had to undress the manikin, spray the cotton skin with water, then quickly re-dress it and pray that it didn't dry too soon," Gonzalez said.

The upgraded Uncle Wiggly sweats automatically through a series of valves and hoses that pump water through dozens of "weep holes" drilled through the metal. They provide even and adjustable water distribution along the 19 sections, which are still independently heated.

One power supply replaces 19 power supplies. Each zone has its own easily replaceable plug-and-play microcontroller to oversee temperature and fluid control and measurement. Measurement updates are shown every second instead of every 20 seconds.

Measurement Technology Northwest's computer software uses color-coded manikin pictorial displays, selectable for any manikin variable. It provides automatic steady-state detection, helpful in identifying the desired manikin temperature.

The operator can also program a work cycle simulation, and view an instantaneous bar graph and time history line graph for any selected manikin variable.

"I can take just a small portion of the graph, zoom in on a selected time period, and then get a good high and low point to get a good average measurement," he said. "You can tell the (thermal resistance) value in a specific region on the manikin or part of the clothing and even add or subtract a piece of clothing without having to rerun the entire test."

Microclimate cooling vests are easily tested now because the manikin automatically calculates the number of watts of heat removed with the garment.

Gonzalez said the new capabilities will enable him to cut testing time in half. He conducted his first comparative test with the improved manikin wearing a Temperate Battle Dress Uniform. Calibrated and validated against the old system, he and Uncle Wiggly are ready to resume testing for the next generation of uniforms.

For more information about USARIEM or the U.S. Army Soldier Systems Center, please visit websites http://www.usariem.army.mil and http://www.natick.army.mil.


This page last updated on 23 January 2004.