Non-Contact Extensometer

“We hired the Good Penguin to assist us with a building a new product requiring embedded linux support for a custom carrier board, something we have not done before. Their service has been excellent. They have been extremely attentive and flexible to meeting our requirements for security improvements, assistance with adopting base image build processes and introducing update capabilities. We look forward to working with them more in the future. I would highly recommend their services.”

– Chris Rowe, Director of Projects at Imetrum, Trust Pilot Review

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Vector Extensometer

An extensometer is a high precision device used to measure the change in length (deformation) of a material specimen when under strain. These measurements are used for evaluating material characteristics which is essential in industries such as civil engineering, manufacturing, aerospace and scientific research.

Traditional extensometers rely on mechanical clips or contact sensors attached to the specimen. However, because they are contact-based, they can influence the measurement, damage delicate specimens, or be damaged in the event of dramatic failures. They also require a level of operator skill (and time) to install and calibrate.

Imetrum has developed the Vector range of video-based, non-contact Extensometers which overcome these limirations. Building on decades of expertise in video measurement and the continuous refinement of their Digital Image Correlation (DIC) algorithms, the Vector range delivers sub-micrometer resolution (< 0.5 µm) at 150 Hz, meeting or exceeding ISO 9513 Class 0.5 and ASTM E83 Class B-1 accuracy standards. Designed for ease of setup and use, Vector extensometers provide a comprehensive and efficient alternative to traditional contact-based systems.

Our Work with Imetrum

Imetrum first approached us as they were migrating their platform from a Windows based x86 system to an ARM based platform. Working with our hardware partner Analogue & Micro, they developed a custom carrier board whilst we developed a Yocto-based Linux distribution tailored for the platform. This required support for a variety of peripherals on the carrier along with support for a third party vendor’s camera sensors. Together with Analogue & Micro, we brought up and validated the hardware and software, thus providing a platform for Imetrum’s application software.

Coming from a Windows background, Imetrum relied on our expertise to accelerate their transition to Embedded Linux. We provided guidance and support throughout the project, giving them the flexibility to learn from us and contribute while still being able to rely on us when needed or to solve more difficult problems. This flexible and collaborative approach allowed for rapid progress to be made.

Protecting Imetrum’s intellectual property was of great importance. Their video-processing algorithms represent significant company investment and needed to be safeguarded against theft, cloning and misuse. We addressed this through a number of measures including security hardening (ensuring it can only be used as intended), implementing an encrypted filesystem (tied to Imetrum’s hardware to prevent theft) and by implementing secure boot (ensuring only Imetrum-signed software could run). During our security hardening work we uncovered and mitigated a serious vulnerability in the vendor provided Linux kernel which we responsibly disclosed, leading to an official fix by the vendor.

A crucial part of this project was the integration of the device’s dual camera sensors which are central to the device’s function. This work involved reproducing complex issues found by Imetrum, characterising and debugging them and working with the camera vendor to address these issues in the camera firmware or Linux drivers. These issues included failures in sensor synchronisation or the failure to deliver frames under certain conditions or corner cases.

We also supported Imetrum in reducing the overall latency of the video capture pipeline and improving determinism. This was required in order to meet the requirements of high frequency closed loop strain measurement. This involved understanding where latency and variability arises in the system, from camera through to serial output, and to perform necessary optimisations.

Beyond security, cameras and optimisation, we also implemented a license key scheme for selective software features, a power failure tolerant software update mechanism and developed and modified kernel drivers. As the product evolved, Imetrum asked for us to provide support for a more powerful ARM based System on Module via a slightly updated carrier board.

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A Successful Outcome

Like so many of our customer engagements, we’ve built a strong relationship with Imetrum through repeated and successful projects over many years. We continue to support them today, including work on vulnerability management and compliance with cyber security regulations, such as the Cyber Resilience Act.

Since the founding of The Good Penguin, we’ve worked closely with our hardware partner Analogue & Micro. This trusting relationship enabled us to efficiently deliver a reliable Linux platform for Imetrum with minimal risk and delay. By collaborating at all stages of development and sometimes working alongside Analogue & Micro’s engineers, we were able to resolve hardware/software interactions quickly, avoiding the common pitfalls of issues being ‘thrown over the fence’ between hardware and software teams.

This project has demonstrated the depth and breadth of our expertise, from hardware bring-up and distribution development, to security and software maintenance, as well as low level and kernel development. Our ability to work with camera systems, as well as to collaborate effectively with our customer and their suppliers to resolve technical issues contributed to the successful delivery of this project.

The Vector range of extensometers launched in September 2023 and became a flagship product for Imetrum. We’re proud to have been part of this and look forward to continuing to work with Imetrum.

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