Applying high precision positioning technology to the cars on our roads
Vehicles on our roads today are nearly all fully driver-controlled, but an ever-increasing proportion have some form of assistance system. As we shift towards completely autonomous driving, we’ll need to see the level of automation growing step-by-step in specific scenarios, such as parking or highway driving. In today’s assisted-driving vehicles, the human driver is still responsible for remaining in-lane or maneuvering between lanes (this is Level 1 in the diagram below). There are already vehicles that sit in the second level, with partially automated systems capable of holding or changing lanes in certain situations. As you move up the scale to Level 3, drivers will even be able to let go of the steering wheel in some scenarios, though they need to be ready to take back control if required. Step up to Level 4, and in some cases, you won’t even need a driver any more. Only once all this has been achieved, does the possibility of delivering fully driverless vehicles become the next feasible target (Level 5).
For autonomous driving to be safe, a range of technologies will need to work in harmony. It’s already possible to bring together camera images, radar and lidar information and high-definition maps to enable a vehicle to pinpoint its location down to 10 cm accuracy, and sense obstacles in a variety of situations. But on their own, these systems can’t fully replace a human driver. For example, as we move towards fully automated driving, a vehicle’s systems will need to rely on a precise position reading to decide whether it’s safe to switch from human to autonomous control. However, if surrounding conditions are poor or there are no distinguishing landmarks, the optical systems may not determine correctly whether autonomous mode can safely be activated. This is a particular issue in Level-4 systems, because it’s here that the driver can hand full control over to the autonomous systems in certain scenarios – deciding when this can be done safely is key.
In situations like this, high precision GNSS can be used with automotive dead reckoning. This brings together satellite navigation information with data from in-vehicle sensors, such as an accelerometer, gyroscope and wheel-speed detectors. This provides accurate and independent positional information, even when GNSS isn’t available. This precise position reading can help pinpoint which segment of a high definition map the vehicle is in, which, combined with geofencing of key areas, can be used to reduce speed for safety reasons, for example. The reading can also be used to calibrate the in-vehicle sensors.