MAPPING SYSTEM FAILS ACCURACY TEST
Another big issue for the Google car project is whether Google’s own mapping base can be used for autonomous driving. Many in the industry say it can’t, which is why the Here mapping division was bought from Nokia by Daimler, Audi and BMW.
Google maps are, in effect, a kind of electronic two-dimensional A-Z map. A device running the maps application relies on GPS satellites to “dead reckon” its position on the road. This isn’t easy because the civilian GPS network is accurate to only 15m.
Although the system has been honed to work very well as a conventional navigation set-up, it is nowhere near intelligent enough to be used for autonomous driving. It cannot place the car on the road with anything like the required accuracy and it cannot work with forward-facing cameras to read the road ahead, identifying potential immobile obstacles such as roadworks and temporary traffic lights.
That’s why the Google test car was equipped with Lidar — a kind of laser-based radar system — for reading the road ahead in 3D. The Here mapping network is a huge step forward over Google maps. The company has used Lidar to map most of western Europe as a kind of 3D “cave”.
Not only are the roads mapped but also the pavements and building frontages. Once a Here-equipped car is inside this cave, it can be positioned to an accuracy of just 10cm — ideal for autonomy.