Unmanned Systems Technology 028 | ecoSUB Robotics AUVs I ECUs focus I Space vehicles insight I AMZ Driverless gotthard I InterDrone 2019 report I ATI WAM 167-BB I Video systems focus I Aerdron HL4 Herculift

7 Platform one KVH has started to roll out a photonic chip that dramatically simplifies the design of a fibre-optic gyroscope (FOG) and reduces its size (writes Nick Flaherty). The chip combines all the photonic elements that are used to control the light used in a coil of fibre. It also detects the changes in the light that come from changes in the gyroscope’s movement, allowing it to be used as an inertial measurement unit (IMU). The chip combines the photonic elements that previously required complex alignment, such as the beam splitter, couplers and an interferometer, in a chip made using a standard CMOS silicon process. These integrated components connect to KVH’s D-shaped fibre that has an elliptical core to get a high accuracy in the FOG and support multiple branches of light. This gives designers extra options for more accurate algorithms, as it avoids the losses incurred when optical components are connected together. This chip is linked to an ASIC for the electrical processing, feedback and control circuits. This combination reduces the size of the FOG by a factor of five with the same power consumption. “This is technology that we expect will transform our FOGs and IMUs,” said Martin Kits van Heyningen, co-founder and chief executive officer of KVH. “We’re now accelerating investment in our core photonic chip technology, which we see as the most significant development in FOGs in decades.” The prototype unit had a higher performance than the existing FOG- based IMUs in angle random walk (ARW) and bias instability, two of the most important performance parameters that contribute to the safety of an autonomous vehicle. The ARW, or noise, of the prototype has been calculated at less than 0.0097 º / √ h. The bias instability, or drift, is 0.02 º /h. Having all the photonic components integrated into one chip also improves the reliability of the FOG as well as allowing it to operate across a wider temperature and humidity range than previous discrete FOG systems. As a result, 30 makers of systems for autonomous vehicles operating at Levels 4 and 5 autonomy are working with the prototype, said Kits van Heyningen, who expects the technology to be qualified in a military aircraft next year. The next step is to combine the light source, photonic chip and electrical chip on a piece of silicon in a package to make the FOG even smaller, as well as reducing the size of the electrical portion of the design. “We’re starting development of a simplified electronics design that can then be reduced to a single custom- integrated chip. That will dramatically reduce the size and cost of the electronics to match the similar gains of the photonic chip,” van Heyningen said. Photonic direction for FOG Navigation Unmanned Systems Technology | October/November 2019 We expect this technology to transform our FOGs and IMUs; we see it as the most significant development in FOGs in decades KVH’s photonic chip reduces the size of a fibre- optic gyro to the one at the front of this display