Moving in the right direction
Drivers and pedestrians often need help getting from point A to point B. Paper maps have gone the way of the dinosaur, being replaced by GPS navigation. But relying on GPS systems to find your way is fraught with problems.
How often have you walked or driven in the wrong direction because your system can’t tell where you are or what direction you are facing?
A more reliable navigation system does not rely on external signals like GPS. Inertial navigation systems (INS) are self-contained, electronic systems that calculate an object’s position, velocity and orientation. An essential component of INS devices are 3-axis gyroscopes that measure rotation and angular velocity in 3 axes: x, y and z.
Micro-electromechanical systems (MEMS) are tiny devices that fit on a circuit board and have a myriad of uses. MEMS-based gyroscope sensors use high-speed, vibrating structures to measure rotation. When the gyro rotates, these structures shift and create small electrical signals that can be amplified and read by a control device. Found in phones, tablets and game controllers, MEMS gyroscopes are small, light and inexpensive. Unfortunately, they lack accuracy, as anyone using a map app can attest.
Precise navigation systems need very sensitive gyroscope sensors, like fibre optic gyroscopes (FOGs). FOGs use light wave interference to measure tiny distances and changes with high accuracy. In these gyroscopes, a laser beam is split into 2: one for reference and one for measurement. When these beams are combined, they create an interference pattern that a digital sensor captures. Gyroscopic rotation changes this pattern, and computer algorithms analyse it to make precise measurements. However, FOGs are usually large and costly, so they are mainly used in space or defence applications.
A gap exists where applications such as self-driving automotives or medical-grade exoskeletons require inertial movement sensors that are more precise than MEMS-based gyroscopes but producible at a fraction of the cost of a FOG.
RMIT’s Integrated Photonics and Applications Centre (InPAC) has partnered with the Australian-based company Advanced Navigation to design and manufacture the world’s most precise, compact and cost-effective gyroscope.
Advanced Navigation is an Australian innovator in AI-based robotics and navigation, developing transformative technologies from inertial and sonar navigation to photonic and quantum sensing. Advanced Navigation is already a leading INS manufacturer, with a range of MEMS- and FOG-based systems to provide position, velocity, acceleration and orientation under the most demanding conditions.
By integrating the controlling optical components of a FOG onto a single chip, the footprint and weight of the sensor can be reduced significantly, while still having a better performance than MEMS-based sensors.
The core principle of the photonic gyroscope is to have active (lasers, modulators and detectors) and passive (resonators or waveguide loops) components integrated onto a single chip.
To date, researchers have successfully fabricated silicon nitride (SiN) optical waveguides on a lithium-niobate-on-insulator (LNOI) platform with integrated electro-optic modulators on the same chip.
The photonic chips will be developed by the InPAC team, with leading-edge facilities for designing and printing these photonic microchips provided by ANFF-VIC and ANFF-QLD, including RMIT’s Micro Nano Research Facility, the Melbourne Centre for Nanofabrication and ANFF-QLD’s facilities at the University of Queensland.
Their photonic gyroscope will squeeze space and military tech into navigation systems for daily life, with accurate sensing for self-driving cars, equipment control for autonomous farming and precision robotics such as exoskeletons for paraplegic patients. And with photonic devices integrated into our phones, we can finally trust our map apps to guide us accurately, ensuring we always head in the right direction.
Published 15 October 2024 in ANFF’s 2024 Casebook ‘ANFF NEXT‘
Posted 11 March 2025
