CASE STUDY: Unattended Ground Sensor system for Digital Barriers plc

Digital Barriers, a UK based provider of advanced surveillance technologies, approached Coalesce in 2011 to develop concepts for a revolutionary Unattended Ground Sensor (UGS) based on their novel RF technology. Such sensors are used to monitor remote sites and assets where communications and power infrastructure are typically limited. Applications include force protection, border security and the monitoring of oil/gas assets.

Conventional UGS systems are typically bulky, difficult and time consuming to deploy, and tend to rely on conventional ‘whip’ antennas that protrude up to a metre from the ground. Digital Barriers’ unique design and technology provided an opportunity to create a compact one-piece unit for rapid deployment.

The main technical challenges were in developing a device made from injection-moulded plastic, rather than cast or machined metal. It would need to be sufficiently robust to survive deployments into harsh terrains, ranging from deserts to frozen tundra, whilst still being lightweight and rapidly deployable. The lead concept to emerge from this phase was based around the idea of an auger with a bespoke deployment tool.

Coalesce carried out the mechanical design work, enabling Digital Barriers to focus on its core strengths around operational product design, RF networking, sensor electronics, and processing software. Although the overall vision for the system was clear from the outset, requirements evolved throughout the process based on input and feedback from various stakeholders, including potential customers.

In order to survive the deployment torque in hard or frozen ground, as well as a huge range of storage and operating temperatures, the main components of the sensor node needed to be tightly toleranced and made from esoteric engineering polymers. Replicating this design in machined prototypes required the utilisation of advanced machining methods. As well as enabling user-testing in the field, this gave Coalesce the opportunity to do some extensive pre-verification mechanical testing in the lab and also in the field.

Coalesce subsequently embarked on the process of commissioning and debugging the injection mould tools. Using British toolmakers and moulders, complex tools were developed quickly so that mouldings were available at the same time that the contract manufacturers were ready to start trial builds. Units from these builds were subjected to formal Mechanical Design Verification Testing (DVT) at Coalesce, in parallel with further System Design Verification Testing by Digital Barriers and additional field trials. Despite the challenging requirements, the first production units were delivered to short timescales.

We are particularly proud of this project, working with a British company to develop a technically challenging, disruptive technology platform in a very short timescale. It is particularly gratifying for engineers used to the long development cycles in the medical device world to see a design progress from initial sketches to marketed product in significantly more compressed timescales.

“Coalesce has played an important role in the mechanical design of Digital Barriers’ innovative RDC product. They provided product design expertise during the initial conceptual design, detailed design and design verification stages, as well as liaison with toolmakers and input to final assembly production. Throughout the development of the RDC product, Coalesce has demonstrated good insight and consideration of the product requirements – along with a significant degree of innovation.”
Paul Bearpark, CTO UGS (Unattended Ground Sensors), Digital Barriers

Digital Barriers was established in 2009 to provide advanced surveillance technologies to the international homeland security and defence markets. Digital Barriers brings innovative new thinking and solutions to the protection of critical national assets, locations and infrastructure. It combines a long heritage in the security and defence sectors, with operational expertise and an understanding of how best to apply and deploy emerging technologies.