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CAD clears the mine field

Article-CAD clears the mine field

CAD clears the mine field

Clearing land mines is one of the dirtiest and most dangerous jobs ground pounders undertake. In an effort to interpose a layer of safety between its troops and the object of such missions, the U.S. Marine Corps issued a request for proposal (RFP) for a remotely-operated mine-clearing system. A small company with origins in its founder's basement responded with the Standardized Teleoperating System (STS), a kit for converting any ground vehicle to remote or semi-autonomous control.

David Parish, president and founder of Omnitech Robotics, seized the USMC contract as his ticket out of the basement. With $750,000 in Phase II award funds, he moved Omnitech into a 16,000 ft2 facility and hired more mechanical, electrical, and software engineers. Parish also invested in a scratch-built CAD installation based on a local-area network of Intel Pentium-class PCs and servers.

Field tests last Summer in Bosnia with U.S. forces serving as part of Operation Joint Endeavor proved the concept of remote-mine detonation using STS. In one case, an STS-equipped M60A3 Panther was damaged by an anti-tank mine that officials say might have inflicted casualties had a crew been on board. Omnitech's approach is modular, scalable, and applicable to other tasks suitable for robotic ground vehicles and water craft.

High standards. Omnitech engineers performed all mechanical, electrical, and software systems development for STS under Microsoft operating systems: DOS, Windows for Workgroups 3.1, Windows 95, Windows NT Workstation, and Windows NT Server.

One seat of Pro/ENGINEER from Parametric Technology Corp., Waltham, MA, running on a 200 MHz Pentium Pro provided for solid modeling of component packaging and interference checking. "The primary benefit here was that fast, accurate modeling allowed us to pack things in nice and tight," Parish says. "Plus, CAM interface modules enabled us to output our designs for manufacturing."

Mechanical engineers perform drafting, assembly drawing, and other MCAD work on five seats of AutoCAD from Autodesk Inc., Sausalito, CA, running on 100 MHz Pentium machines. In all, a network of over 30 Intel-based machines and a wide variety of software packages were used to handle printed circuit board design, sheet metal pressing, software engineering, testing, and administrative functions.

"Not only was our STS product designed using PCs exclusively, its major subsystems--the Operator Control Unit and Vehicle Control Unit--use Intel-based embedded controllers running DOS," Parish relates.

According to Parish, some of the advantages of using "mainstream" computer products is that they integrate quickly and provide print and plotter sharing, automated backups, and Internet access without specialized hardware, system administration, and maintenance.

No one at the wheel. Think of the STS as turning a tank or a bulldozer into a really, really big Radio Shack R/C car. Omnitech delivers the STS product as a strap-on kit, consisting of an Operator Control Unit (OCU), Vehicle Control Unit (VCU), a number of High Integration Actuators (HIA), a System Input/Output (SIO) device, a Video Transmitter Unit (VTU), and a Pan/Tilt Unit (PTU) for orienting the camera that supplies the operator with a robot's eye view of the road.

An important feature of STS conversions is that the vehicle is always man-driveable. Auto to manual control is achieved by just flicking a switch.

The STS architecture is capable of supporting up to 20 actuators, all with the same basic control system. Such scalebility is possible because control is distributed out to individual actuators, so each has its own digital servo control processor and microcontroller. A sealed HIA module also contains a motor, potentiometer feedback element, optical encoder, output load cell, and current and temperature sensors.

A standard HIA weighs 37 lbs and provides 100w continuous power and 600w peak. Output is via a push/pull cable or pull-only cable terminating at the control mechanism for that actuator. Various cables are available allowing up to 1,000 lbs of push/pull control force or 3,000 lbs of pull-only force.

Actuators interface to a Controller Area Network (CAN), for which the SIO serves as an intelligent node. The VCU contains the central control computer and all STS control interfaces. The unit also houses the telemetry radio transceiver. The separate VTU provides audio and video links for teleoperation applications.

Kits for particular vehicles differ only in the number of actuators and the layout of the OCU control panel. Otherwise, components are standard. The conversion kit for the very manual D7G dozer, for example, has 13 actuators; while the M1 tank version has three.

This standardization is by design. "We wanted to keep the automation practical, no weird science," Parish recalls. "There might be better ways to implement teleoperation for specific vehicles, but not without doing component design." The original contract favored so-called "non-developmental items" (NDIs), military jargon for off-the-shelf components. The PC controllers, LCD displays, and actuators Omnitech uses for STS kits are all NDIs.

"We saved a lot of engineering costs with a very capable actuator and PCs," Parish says. The principle at Omnitech is to achieve increments of cleverness on proven concepts. This may not be visionary, Parish admits, but it is a way to get robotics out of the laboratory and into the field. In the case of STS, it's the mine field.

Making tracks. Specialized engineering vehicles for tackling mines date back to WWII. In particular, the Allies' invasion of Normandy occasioned a number of innovative--and some outright bizarre--designs for equipment intended to detonate mines harmlessly, such as rollers, rakes, and flails. Nevertheless, the tanks these attachments were affixed to required crews to operate them.

With Omnitech's STS, the crew is removed from harm's way. In Bosnia, the U.S. Army has fielded seven STS-converted M60 Panther tanks for use in proofing roads suspected of having mines. In this capacity, the tank has its turret removed and an assembly of heavy rollers is added. Nothing subtle here: if there are mines, the rollers will set them off.

The experimental Robotic Countermine Vehicle (ROCV) is an M1 conversion, also turret-less, but possessing an array of mine clearance equipment. It sports a track-width plow for digging up mines; dual mine clearing line charges, which are rocket-deployed ropes of explosives for setting off mines; and the Pathway clear lane marking system for showing follow-on forces where the ROCV has cleared the way. In practice, crews will drive this vehicle until a mine field is encountered. The crew will then dismount and use STS to do the dirty work.

The USMC Joint Amphibious Mine Countermeasures (JAMC) program provided the original impetus for STS. The requirement was for a teleoperated vehicle that could be deployed from a hovercraft in shallow water to clear mines from a landing beach. The Marines selected the D7G dozer for this application, equipped with STS, and carrying a variety of surf and shore detection, clearance, and marking equipment.

Other military vehicles, including the Hummer, have also been converted with STS kits for mine clearance and other applications. In a non-military role, Parish says STS is being considered for automobile endurance testing, ore-mining operations, security, and work in hazardous environments.

With funding from NASA and the JPL, Omnitech is developing the Modular Autonomous Robotic System (MARS), which is a set of software tools for programming robots in a structured environment. MARS would enable a vehicle with STS and a navigation system, such as GPS, to operate without direct supervision.

Omnitech's approach to robotics is, in a word, methodical. This is exactly as Parish intends it, as the industry is something of a technological mine field itself. "Too many robotics people want to publish papers," he believes. "If the technology isn't used, who cares?"

TAGS: Aerospace
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