Sensor Fusion Algorithm for Indoor Navigation Especially on Urban Transit Systems

Technology Overview

Common apps like Google Maps and City Mapper face challenges in determining accurate users' location in environment with limited GPS signals, limited data and WiFi connection. GPS signal is often reduced in railway infrastructure and underground tunnels, rendering smartphones apps unable to respond accurately with relevant and timely information.

Metro API is a software library package that provides accurate location information in both outdoor and indoor environment. The Metro API software application programming interface (API) provides apps with accurate location information especially in underground transport networks. The API enables a vast range of functionalities that are currently challenging to achieve, such as:

  • informing the user of the next station so they can prepare to alight,
  • notifying them about delays or line closures so they can take an alternative route, and
  • informing them of the best places to stand on the platform to avoid congestion and minimise interchange times.

The API can provide accurate position information at every stage of their metro or underground journey. For example, a users will be guided turn-by-turn as he/she walks to the platform and, once on the train, he/she will receive a notification at an appropriate time to inform that he/she would need to alight before their destination systems.

Technology Features & Specifications

Metro API uses a combination of sensors on the smart phones together with a patent pending “sensor fusion” algorithm developed for underground environments. To precisely determine a user’s location, this algorithm does not rely on a single signal type, but instead adaptively uses signals available at a specific location, combining this information with other measurements from smartphone sensors, such as the accelerometer.

This allows accurate position information in places without signals from GPS satellite, such as underground infrastructure. It does not require beacons or Wi-Fi devices to be purposefully deployed across the network. The algorithm does not require Internet connection to function. 

Algorithm has been tested to deliver accuracy of shorter than 10 meters. Software library is available initially for Android OS and iOS smart phones, and support for other platforms will be added later. Software has been tested on a vast majority of smart phones.

Potential Applications

This technology is capable of deducing the underground position of the smartphone even without GPS signals. It also detects if the user is standing on a train. The Metro API will be useful especially in trains underground where standard apps have challenges delivering GPS satellite signals across to users.

The APIs enable apps to drastically improve their positioning accuracy thus enhancing users' experience nagivating their metro journey. The technology is infrastructure-free and works on all the world’s major metro systems such the London Underground, the Paris Metro and Singapore MRT network. The API can be implemented on any mobile app to enable a seamless metro navigation experience by users.

Market Trends and Opportunities

According to Frost & Sullivan, market for indoor positioning technology is estimated to be greater than US$3.5 million by 2018. The growth is driven by denser urban cities of hugh buildings and indoor spaces without GPS reception. Locating valued-assets and individuals, indoor navigation and context-awareness are some applications being explored. Technology is being leveraged in the context of smart cities.

Customer Benefits

  • Easy metro navigation
  • Convenient
  • Navigational signals can be received by users underground with no or minimal disruptions.


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