Machine Design

Uncle Sam to mobile robot makers: Don't reinvent the wheel

The concept behind unmanned ground vehicles (UGVs) makes perfect sense: Use a sensor-studded mobile platform instead of a GI when inspecting vehicles or houses that could be booby trapped.

Inside a modern UGV

The Tags-CX (Tactical Amphibious Ground Support System – Common Experimental) vehicle is an example of a JAUS-compliant semiautonomous UGV. It is a joint project of Applied Perception Inc., Cranberry Township, Pa., the U.S. Army's Tank-Automotive Research, Development, and Engineering Center, and Dumur Industries in Canada. Tags-CX is used for integrating and assessing new technologies. It can be outfitted with such options as a 15-ft telescoping mast, 2D laser rangefinder, 24-GHz radars, differential GPS, and FLIR cameras. Possible payloads include weapon modules, manual drive-by-wire, damage control, storage, and fuel. On the Tags-CX, JAUS promotes plug-and-play with a standard interface for controls and payloads.

RE2 Inc. is one of the robotics firms heavily engaged in JAUS work. A spin-off from Carnegie Mellon University, RE2 devised a software-development kit that promotes JAUS messaging. Among other things, it provides a message library of C/C++ functions to pack and unpack JAUS messages.

One project on which RE2 is working is the U.S. Marine Corps' Gladiator Tactical Unmanned Ground Vehicle Program. The Gladiator will be a teleoperated unmanned ground vehicle for combat and reconnaissance.

Unmanned vehicles are proving to be so effective that Congress recently mandated 30% of the U.S. military be unmanned by 2015. So the demand for them is mushrooming. And defense contractors have developed specialized robots for a multitude of tasks.

The downside of this trend is that most robotic platforms have their own unique design, sharing few elements with other similar devices. The same can be said for the controls. This has meant that GIs trained to run one type of robot may need to learn other types almost from scratch.

The Army now wants to make it easier for GIs to come up to speed on UGVs by devising a common set of operator controls. Similarly, the DoD wants robot developers to concentrate on new UGV capabilities rather than on making new gear talk with existing parts of the robot. To this end, it is sponsoring the development of standards for how different subsystems in a UGV communicate with each other.

One of these standards is called JAUS, for Joint Architecture for Unmanned Systems. Among other things, it ensures all UGVs work with each other. It also simplifies the task of adding options to a robot by defining a common communication protocol. Though it was designed for UGVs, JAUS will likely find use in unmanned vehicles for traveling on and under water and in the air.

JAUS is basically a set of messages that can pass between subsystems (such as the base robot platform or the operator terminal) and payloads (such as manipulator arms). Though JAUS promotes interoperability, it only goes so far in its present form. For example, it is still possible that two JAUS-compatible systems will be unable to talk with each other if they use different message transport schemes (say, UDP/IP and TCP/IP).

Companies working with the JAUS committee say a set of best practices should help overcome such difficulties. JAUS also has been adopted as a standard by the Society of Automotive Engineers. SAE committees are working on an improved version of JAUS which gives equipment following the standard more of a plug-and-play quality. Other improvements should expand unmanned uses, mission planning, and support weapons on UGVs.

Applied Perception Inc.,,
JAUS software development kit, go to
JAUS Working Group,
RE2 Inc.

Trekking with a Sherpa
The Sherpa was developed by RE2 Inc., Pittsburgh, for Carnegie Mellon University. Its platform was used by the university's team in Darpa's Perception for Off-Road Robotics program. Now available commercially, Sherpa can be modified with such add-ons as an electric start generator, a retractable sensor mast, dualies, suspension deflection potentiometers and a tactile sensor bumper.

The Sherpa, for example, works via both computer and manual control. In manual mode, it can be driven as a traditional ATV. In computer control mode, it is teleoperated or controlled by an autonomous navigation system (not included). The control interface implements JAUS messages over an Ethernet.

The little 98-in.-long UGV weighs about 1,400 lb and carries a 683-cc gas engine. Front suspension elements are MacPherson struts and the rear is a fully independent suspension. It can hit 40 mph and carry a 700-lb payload.

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