Ending Disconnect Between Subsystems in Unmanned Ground Vehicles
Interoperability standards are being defined and tested to break the data exchange impasse presented by proprietary architectures in unmanned ground vehicles.
Unmanned ground vehicles (UGVs) can be counted among the unsung heroes of modern warfare. They are the robotic equivalent of the hard-working people one might see on a cable television profile. They possess unique skills that make them truly modern marvels, and they perform dangerous or dirty jobs that most people would turn down without exceptional compensation. They can perform search and recovery in dangerous, remote places; conduct reconnaissance in dense, urban locations; detect and defuse explosives; and handle hazardous materials, as well as other tasks to mitigate risks to personnel or to reach places that are inaccessible to soldiers.
Cooperation is a Moving Target
UGVs are typically comprised of cameras, manipulator arms, sensors, controllers, and other subsystems that exchange data with each other as well as manned systems to support their overall missions. Many of those subsystems are commercial off-the-shelf (COTS) systems with proprietary architectures that present inefficiencies to the Department of Defense (DoD) because of the costs and the challenges of customizing them for end users. Additionally, the burgeoning use of UGVs among allies creates an obvious need to ensure that the robots cooperate and seamlessly interact with each other to achieve the goals of a particular mission. One recent event where UGVs could potentially have been effective was the Fukushima nuclear disaster in 2011. If, at the time, unique sensors were interoperable with standardized modular interfaces, UGVs might have been deployed to detect radiation.
To spur better modularity in UGVs, the United States Army’s Project Manager, Force Projection (PM FP) has developed initial interoperability standards for its Unmanned Ground Vehicle (UGV) Interoperability Profile (IOP), which started with IOP V0 in 2011. The goal is to produce a “standardized library of physical, electrical, and logical (messaging) interfaces…that they can use to define a common interoperability profile…specific to a certain robotic vehicle or platform. The instantiation specifies which interfaces and interoperability attributes, from among those defined in the overarching IOP, are to be implemented on a particular robotics and autonomous system (RAS).”* The Army’s Tank Automotive Research, Development and Engineering Center (TARDEC) provides tools to test UGV IOP compliance.
Addressing Changing Payloads and Capabilities
One of the critical issues facing end users is that the “mission” modules specific to a payload (e.g. cameras or chemical sensors for surveillance missions) be hot-swappable in the field. That means they must function the same across UGV manufacturers and have a common interface that can be re-configured into a different UGV deployed for a different mission.
Mark Mazzara, interoperability manager, RS JPO, noted that UGV IOPs aim to address connectivity challenges between subsystems to ensure that each uses the same radio frequency and waveform, and that they are “compatible in terms of information assurance technologies.” He added that IOPs must also account for significant increases in a robot’s capabilities. Therefore, to maintain controllability, the software update that accompanies the upgrade must also be standardized. The message set, known as Joint Architecture for Unmanned Systems (JAUS) specifies common data formats and protocols that vendors must follow to improve modularity and interoperability in UGVs.
IOPs: Connecting Payloads, HMI, and Communications to the System
The initial IOP standards are broken into four sub-IOPs. For the most part, the connectors specified in the IOPs are fairly common, and they are intended to account for all the system requirements rather than adversely affect the vehicles’ performance. The rest of this section summarizes the different IOPs and some of their expectations for connectors with information provided by Mazzara.
- Payload IOP: Payloads (cameras, manipulator arms, sensors, etc.) should connect with robots via either MIL-DTL-38999L series II 13-pin, 10-35 insert, with nominal rotational keyway; or the larger MIL-DTL-38999L series II 22-pin, 12-35 insert, with nominal rotational keyway. For electrical power interfaces, 12VDC, 24VDC, and 48VDC are allowed.
- Control IOP: Specifies the Operator Control Unit (OCU) logical architecture standards, and Human Machine Interface (HMI) requirements. “For controllers, USB 2.0 connectors are allowable for general applications. Several variants of the 2.5mm and 3.5mm TRS/TS (tip, ring, sleeve/mono) are allowable for audio interfaces. Serial interfaces defined by EIA/TIA-232-F/RS-232 are allowable in most cases. Video interfaces should be at least one of the following: CEA-861-E, mini HDMI, DVI, VGA. Ethernet RJ45 connectors are applicable.”
- Communications IOP: The radios should connect with the robots using the same MIL-DTL connectors and keyways as in the Payload IOP. In addition, “the external antenna connector of the radio system should use any of the following: SMA-female; TNC-female; or N type-female. The antenna port of the radio system should be weatherproof, low loss with 50-Ohm impedance supporting frequency range of 200MHz to 6,000MHz. And the input power should be auto-ranging supporting a minimum voltage range of 10 to 28VDC.”
Mazzara stressed that any connector types adopted in the future will be non-proprietary interfaces.
As more robotics systems vendors serving the military strive to conform to IOP interoperability standards, designers should work with connector vendors to select solutions that not only ensure modularity but also address the unique needs of the system itself, such as the harsh operating environments and the overall performance and functionality of the system. The result will be systems that are cost-effective and flexible enough to be deployed and controlled by personnel without the hurdles associated with using disparate models and vendors of UGVs or even among robots across several allied forces.
* This information is taken from the paper A Modular Open System Architecture Strategy for Robotics and Autonomous Systems, by M.S. Moore, B. Thomasmeyer, D. Kent, M. Mazzara, F. Lentine, and D. Martin, presented at the autonomous ground systems (AGS) technical session conducted at the 2015 NDIA Ground Vehicle Systems Engineering and Technology Symposium, in Novi, Mich., in August 2015.
Author Chris Warner is a freelance technology writer who comes from an old Western Electric family. He has more than 15 years experience in covering the electronic components industry.