Autonomous cars rely heavily on a GPS signal to get around, but as many streets become densely populated by tall buildings on both sides, the signal at ground level can be lost or degraded. This is because satellite signals are obscured, or because radio waves bounce off surroundings and form multiple signal paths.
According to the Council on Tall Buildings and Urban Habitat (CTBUH), the number of tall buildings (above 200 metres) has risen by 650% in the last five years. This is set to increase again by up to 20% in 2020.
These tall buildings are not the only issue with GPS dependency. Sunspots formed during the sun’s 11-year magnetic field cycle cause marked changes in the solar wind. This subsequently impacts the upper atmosphere which can in turn interfere with GPS satellites.
The interruption of GPS signals can have safety and operational implications for autonomous systems that rely heavily on satellite-based navigation.
This is why Paul Newman, CTO and founder of British autonomous vehicle start-up Oxbotica, has worked on an alternative using a mix of radars, cameras and lasers.
He claims that other companies have attempted to do the same using inertial navigation units, combining GPS, gyroscopes and accelerometers. This would reduce the reliance on GPS. However, he claims that Oxbotica is the only company doing this with computer vision, laser or radar.
“Our localization system using radar – even when you have clear skies, beats anything you get from a GPS signal, it sees through dust or rain. The independence from GPS, whether you’re in a canyon or underground means you can use your own sensors to see what’s going on, and it all remains consistent,” he says.
The technology therefore can be used in mines, shuttles, warehouses and in ports. It means that if a vehicle is going through a forest where the sky can’t be seen or through a quarry, the line of code doesn’t need to change. The Universal Autonomy software platform is already in use in mines, quarries, warehouses and in cities across Europe, Asia and America which Newman suggests are ‘urban canyons’ – where tall buildings create GPS blind spots.
“If GPS is there, you use it, but don’t rely on it. If you go underground there is no GPS. We’re seeing clients who have been dependent on GPS for years – we are now showing them that their vehicles have not been where they think they are, they’re metres out and they didn’t know,” says Newman.