MEMS Sensor Fusion—The Key to Ubiquitous Positioning?

By Rahul Gupta On August 27, 2012
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The ability to find out exactly where we are, wherever we are, is something many of us are already starting to take for granted.

As governments, businesses and individuals increasingly rely on technologies founded on GNSS positioning, the race is on to provide accurate, reliable positioning in environments where GNSS has traditionally been weak or denied.

Ubiquitous positioning promises multiple applications—from extending and completing the fabric of augmented reality, to facilitating targeted advertising, stock tracking, airport navigation and museum tours. And so far, the drive to realise it has yielded a multitude of possible solutions.

Many take advantage of local wireless networks to augment GNSS positioning, from the specially created to the pre-existing, such as local networks of Wi-Fi hotspots. Potential peer-to-peer (P2P) solutions, meanwhile, aim to enhance positioning reliability for whole groups of GNSS users by enabling the sharing of key positioning information between their individual devices.

Is MEMS Sensor Fusion the Key?

One of the most promising, and best-established, technologies in the race to deliver ubiquitous positioning is the fusion of GNSS signals with data output by MEMS inertial sensors.

MEMS inertial sensors are included as standard in many commercial location-aware devices (such as smartphones). These sensors often include:

  • Gyroscopes
  • Accelerometers
  • Barometers
  • Magnetometers

Information from such sensors can be used to bridge gaps in GNSS reception, providing data concerning the device’s motion until a new GNSS fix is established.

Unlike solutions which support GNSS positioning with signals from local Wi-Fi or augmentation networks, enhancing positioning accuracy with MEMS sensors requires no external infrastructure—and unlike potential P2P solutions, it doesn’t need anyone to be standing nearby.

In terms of truly ubiquitous positioning, it therefore has the distinct advantage of being a solution that will perform as well in a deep mountain ravine as down in the depths of the Louvre.

Testing MEMs Sensor Fusion

Fusing the data from multiple MEMS inertial sensors with the data from a GNSS receiver requires the creation of sensor fusion algorithms. Since perfecting these algorithms during device R&D can be difficult, slow and costly, Spirent has developed a dedicated tool called SimSENSOR.

Put simply, SimSENSOR augments the capabilities of our Multi-GNSS simulators by simulating the output of a device’s MEMS inertial sensors. This enables algorithm performance testing to take place within controlled, repeatable lab conditions—for higher-quality sensor fusion, and faster, lower cost device R&D.

A Crucial Technology

While tomorrow’s positioning solutions will almost certainly draw on a combination of technologies and techniques, the relative strengths of a sensor fusion approach—and the relative ubiquity of MEMS inertial sensors—seem set to guarantee its inclusion as key component in many ubiquitous positioning systems.

If you’re working in this field and you would like to find out more about SimSENSOR, read about it here.

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