COM Express: The Architecture to Support the Future of Robotics & Unmanned Systems

April 1, 2024

Embedded computing systems to support robotic applications – particularly in aerospace and defense environments – demand special considerations including robust I/O, enhanced processing capabilities, vibration tolerance, and reduced footprint. Capitalizing on proven COM Express architecture allows for integration with existing systems as well as expansion using the most advanced peripherals available for reliable performance.

COM Express is a family of modular, small-form-factor computer-on-module (COM) specifications. The COM Express specification is one of many developed by PCI Industrial Computer Manufacturers Group (PICMG), whose goal is to translate desktop PCI standards to industrial applications. PICMG is a nonprofit consortium of companies and organizations, that collaboratively develop open standards for high-performance telecommunications, military, industrial, and general-purpose embedded computing applications.

The goal of all the different COM Express specifications is to fill the computing gap between high-cost, high-performance devices like VPX and COM-HPC, and lower-cost, Raspberry Pi-like devices. This modular system allows mid-range processing and networking capabilities that can be applied to aerospace, defense, robotics, autonomous systems, transportation, and other technology-driven markets.

COM Express is inherently flexible, allowing designers and engineers to select and combine individual modules to create custom hardware configurations. This can help meet specific application requirements and optimize system performance and any SWaP-C2 requirements. When using COM Express architecture, the computer-on-module has connectors that are soldered directly to the carrier board, and the enclosure is then built around the board.

A primary feature that separates COM Express boards from traditional single-board computers is the flexibility to mix and match various off-the-shelf modules. The COM module provides the high-speed computing functions that are common to most applications including the CPU, memory, graphics, Ethernet and USB communications, SSD interface, and expansion buses. The carrier board is then designed to meet the application’s I/O or subsystem requirements.

Faster, Better Design and Deployment with COM

By utilizing a two-board system – the carrier board with dedicated I/O and required subsystems and the COM Express processor module containing the CPU and other processing components – engineers can develop, design, prototype, and test rapidly for faster time to market. Estimates suggest that the time to design a custom carrier board is approximately half that of a traditional, full-custom OEM board.

The modularity of the platform allows designers and engineers to focus on developing the core functionality of the system, namely those housed in the carrier board. Perhaps the most beneficial element of COM Express architecture is the ability to optimize the carrier board to include the specific I/O for the application. The signals necessary to interface the I/O are brought down from the COM Express board via mating connectors, and the carrier board’s functionality and mechanical footprint can be tailored to the application.

COM Express architecture allows manufacturers and integrators to rapidly respond to market fluctuations, competitive forces, and new technologies. They can quickly and efficiently modify existing designs, inexpensively broadening their product portfolios through the plug-and-play nature of COM modules and carrier boards.

Meeting Environmental and SWaP-C2 Requirements

Another advantage of COM Express/custom carrier board architecture is the absence of cabling from the system. Utilizing COM Express allows a custom carrier board to be designed to the exact mechanical dimensions to allow I/O connectors to be soldered directly to the PCB in such a way as to allow external access without internal cables. The mounting of all connectors directly to the carrier board eliminates internal cable connections – removing a common point of failure. This makes COM solutions ideal for use in high shock and vibe environments, specifically those found in autonomous drone deployments for sea, air, and ground.

COM Express specifications are also intentionally architected to support rugged computing in diverse, potentially harsh, environments, where temperature poses a barrier. In these environments, computers must be able to withstand extreme operating temperatures. Further, since external thermal conditions cannot be controlled, engineers must design devices with minimal heat production. A wide variety of COM modules have a -40 °C to +85 °C operating temperature – and up to a 15-year lifecycle guarantee. Pairing these COM modules with a carrier board specifically designed to meet the same diverse environmental conditions allows for fanless, solid-state operation in many applications.

Specifically, as UAVs become more complex, they require more processing power and often include data communications networking hardware. The range and capability of these platforms are, ultimately, limited by size and weight; fuel costs increase as the size and weight of the UAV increase. COM Express solutions expand or reduce on a horizontal plane to meet the available footprint and achieve the necessary SWaP-C2 optimization.

Specific Unmanned & Robotics Use Cases

Hyperspectral Imaging for UAVs

A leading manufacturer of hyperspectral imaging systems deploys solutions for use in military applications including remote surveillance, target tracking, and missile and mine detection. Among these solutions is a system for unmanned aerial vehicles (UAVs). This system is particularly susceptible to SWaP-C2 constraints as well as extreme vibration and shock tolerance.

After performing a detailed analysis of the mechanical and environmental requirements, the company’s partner engineering firm specified a COM Express Mini Type 10 carrier board. However, due to the unique enclosure of the end product and expansive I/O, they ultimately proceeded with a two-carrier board solution.

Driving factors for the use of COM Express in this design included the need to meet a constricted timeline, a unique available footprint, and the ability to tailor the product to meet very specific I/O requirements. The project was completed in 11 weeks from initial prototyping to full production. With the capability to integrate two boards, connected at a right angle, the design team was able to maximize the processing capabilities while including the application-specific I/O.

AR Mapping and Geospatial Recording

As their business grew, one solutions provider saw an increasing number of their AR mapping and geospatial recording systems being deployed in military UAVs for the display of live video of ground-based targets, overlaid with realtime data. For the next generation of their systems, they sought a computing platform that would strategically move them from low-volume, hobbyist production to a full-scale, industrial, widely available product.

This application necessitated high-performance processing onboard the deployed system. Combined with size restraints and dense I/O requirements – and the aforementioned desire for an industrial, high-volume solution – COM Express quickly emerged as the preferred architecture for the redesign. By utilizing a Compact Type 6 carrier and daughter board, the product met all of the SWaP-C2 requirements and facilitated the integration of the robust I/O mix including Gigabit Ethernet, USB 3.0, composite and component video, DisplayPort, HDMI, SDI, CAN, ARINC, RS-232, RS-284, PS/2, differential audio, GPIO, A/D inputs, and D/A outputs.

Robotic Exoskeleton Control

A not-for-profit research institute developed a powered exoskeleton to provide increased mobility and independence to people with lower limb paralysis. The exoskeleton allows users to stand up and walk through a variety of environments, including up and down stairs and ramps, and across both flat and bumpy terrain. The exoskeleton utilizes powered actuators located in the hip, knee, and ankle to provide users with a smooth and natural walking motion.

After a thorough prototyping process with a Raspberry Pi-based computer, the institute partnered with an engineering and manufacturing firm to develop a custom solution for control of the exoskeleton.

The extremely reduced available space led the engineering partner to specify COM Express. The engineering team ultimately designed the smallest available, full-feature Compact Type 6 Carrier Board at 95 millimeters square – identical in size to a Compact Type 6 COM Express module. The engineering team was able to incorporate the required I/O into the small footprint, including Gigabit Ethernet, USB 3.0, USB 2.0, GPIO, RS-232, and Mini DisplayPort.

By using COM architecture, engineers can provide application-specific solutions without the design, time, cost, and lifecycle management issues inherent to a more traditional design. Utilizing a COM Express architecture allows engineers and manufacturers to dedicate the bulk of development and design time to the carrier board, tailoring the I/O to meet the exact specifications for robotics and unmanned systems. Finally, the flexibility of the architecture allows the carrier board to be designed to the available mechanical dimensions – often reduced in unmanned systems – while eliminating failure points associated with high shock and vibe environments.

This article was written by Drew Thompson, Technical Writer, Sealevel Systems, Inc., (Liberty, SC). For more information visit here  .

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