OUTPOST, December 12, 2005 — 1

U.S. Army Yuma Proving Ground, Yuma, Arizona 85365 YPG Website: www.yuma.army.mil Volume 36, No. 107-–– December 12, 2005

Laser-based bore mapping technol-ogy developed at Yuma ProvingGround is keeping gun tube testingand evaluation on the cutting edge ofmeasurement and inspection technol-ogy.

After determining, in late 2000, thatsomething new was needed to improveinspections inside large and small guntubes, David Le, mechanical engineerin Ground Combat System’s Metrol-ogy and Simulation Division, con-tacted a Bellevue, Wash., companythat specializes in advanced laser in-spection technology. Working with Le,and based on YPG’s requirements,Laser Techniques Co. built the Army’sfirst-ever laser-based bore mappingsystem for .50 caliber gun tubes. Lesaid it benefits YPG, the customerand the Soldier by quickly findingdesign issues during the early stagesof research and development.

Today, that system is in use provid-ing high quality data feedback to cus-tomers at the proving ground con-ducting research and development ofmunitions and weapons systems likethe .50 caliber M2 machine gun, the81 mm and 60 mm mortars and 155mm towed and self-propelled cannon.The laser-based inspection system(LBIS) conducts high resolution, 360

Yuma Proving Ground pioneerslaser-based mapping technology

degree inspections of gun tubes at ahigh rate of speed, Le said. It can mapthe interior of an entire M2 .50 calibergun barrel in less than seven min-utes, and is capable of accuratelymapping the nearly 30-foot-long 155

mm gun tube in only 17 minutes. Us-ing the old system took two hours andprovided only primitive data, Lepointed out.

The laser-based scanning systemprovides customers with standard or

high resolution images that can beanalyzed for erosion, wear or pitting.Customers get a true picture of a bore’scondition for the very first time

(See Laser-based mapping on pg. 3)

New technology benefits YPG, customer andthe Soldier in research and development

UP CLOSE AND PERSONAL – The laser-based bore mapping system scope prepares to enter a developmental 81mm tube. The scope will send back three dimensional electronic data. (Photos by Public Affairs Staff)

OUTPOST, December 12, 2005 — 3

through the scope’s three dimen-sional data capturing capabilities, Lesaid.

The system not only shows thewear on a tube, it also gives the length,width and depth of any anomalies.The accurate and quantitative three-dimensional scan results can also beused to create modeling and simula-tion packages, and its uniqueLaserVideo™ images provide a visualindication of the gun tube’s surface.

Gun tube inspection technologyhas steadily evolved over the past 25years and YPG has become a pioneerin this field. High-tech testing andevaluation tools are being developedwithin the industry to meet the de-mands and challenges of finding thecapabilities and limitations of mod-ern weapons systems, which are nowusually a complex system-of-systems.

In the pre-Desert Storm 1980’s,gun tubes were inspected by handusing a mechanical “star” gauge thathad to ride in the barrel’s grooves, Lesaid. It only measures diameters andtakes two people three hours to manu-ally measure a large tube. That in-spection only returns data from twoset points on the tube, zero and 90degrees. It was also possible thatcopper build up could slow the in-spection and the gauge could actu-ally get stuck inside the barrel.

In the early 1990's, electronic stargauges were developed. They weresimilar to earlier gauges, but testersand evaluators could access the datavia computer to enhance speed andaccuracy, Le explained. This inspec-tion took one person between oneand two hours to complete, but still

only yielded data at the zero and 90degree points.

In the mid-1990's came the videobore scope that allowed 360 degreevideo data. This was a high technol-ogy revolution of video inspection, Lesaid. The video was 480 lines of reso-lution and provided video documen-tation for the customer. The mostrecent video bore scope, developedabout 1999, provides 700 lines of reso-lution and has a laser positioning sys-tem to quickly locate specific spots. Indeveloping these scopes, off-the-shelftechnology was modified to fit YPG’stest and evaluation application re-quirements, Le said. The drawbackof this technology, however, was thatthe images could be distorted anddata analysis was still labor intensiveand time consuming. In addition,

video bore scope inspection is sub-ject to operator interpretation.

In early 2000, Le started workingand coordinating with Laser Tech-niques to develop the laser-basedbore mapping system because hesaw the need for a new instrumentthat could perform automated, quan-titative, non-contact measurementsin a short period of time.

The laser spot size is approxi-mately 2/1000th of an inch in diam-eter when it is projected onto thebarrel surface and the sensor is ca-pable of acquiring over 7,000 datapoints per revolution inside the bar-rel, Le said; adding that this level ofresolution is a long way from the twozero and 90 degree data points thatwere attainable just a few years ago.

PERFECTIONIST AT HEART – David Le, mechanical engineer in the Weap-ons and Munitions Division, inspects a sample computer readout of thethree dimensional data captured by the laser-based bore mapping system.

Precision calibration rings are usedbefore every setup to insure uniformaccuracy. In a smooth-bore 42-inchmortar tube, the sensor scans at 270degrees per second and moves aboutan inch down the tube during thattick. It can be set up to scan at differ-ent rates and intervals. If it is set upto scan every 50- thousandth of aninch for 42 inches, Le determines thescope will rotate 840 times in 12.9minutes.

Live data is transmitted to a com-puter that uses specialized softwareto assist in analysis and can be cap-tured for later study and manipula-tion. That software allows users toaccurately locate and measure dam-age or wear within 1/1000th of aninch.

All of this technology has helpedput Yuma Proving Ground in theforefront the testing and evaluationof endurance and performance of con-ventional and experimental muni-tions.

For now, all work is done in the labwith detached gun barrels. Le saidthe next generation will consist ofportable field inspection systems thatcan scan a barrel without disassem-bly. Mostly, the field systems wouldbe providing preliminary results, butthe data could be transmitted througha network back to the lab for in-depthanalysis.

These systems are already in thepreliminary design stage. If funded,Le expects the systems will be builtand tested at YPG.

Laser-based mapping (Continued from page 1)