Tõnu Laas – How does a Self-Driving Car Know Where it is?


An autonomous vehicle is one that can function like a regular vehicle, monitor its surroundings and navigate without the help of a driver. A self-driving, or robotic vehicle can react to any situation faster than a human being, and be more precise and careful, says Tõnu Laas, Professor of applied physics at the Tallinn University School of Natural Sciences and Health.

As humans and animals, self-driving cars also need information received from their surroundings to calculate the odds of upcoming obstacles. Living creatures tend to receive passive signals via sight and hearing. Bats actively emit ultrasonic signals, and use the reflections to decide on the distance, size and location of objects.

Similarly, self-driving cars have various ways to ‘feel’ their surroundings. A small robotic car can decide whether it is on the right path merely by analysing the hue of the surface under it. By emitting and receiving ultrasonic signals, it can determine the distance to various objects.

Of course, self-driving cars need more than changes in brightness and ultrasonic waves to function. Self-driving cars operate according to pre-programmed reactions to upcoming situations. To drive along the right path, the car needs to use GPS. The GPS system can roughly point the car’s location, but it is not accurate enough to follow lanes.

One of the ways cars can see objects is robotic sight, which should recognize familiar objects – traffic signs, traffic lights, and pedestrians. In addition, to have a better grasp on their surroundings, the car must actively emit signals. The signals are no longer ultrasonic, but electromagnetic. By emitting and receiving radar signals, the car can not only recognize objects – cars, people, animals, etc. – but also calculate their moving speeds.

Additional laser scanning with the help of a LIDAR system helps the car form a 3D image of its surroundings. Combining such signals, received from various systems, helps the car ‘know’ what is around it and quickly react in order to take decisive actions while driving along.

In the future, self-driving cars will enhance road safety, as they eliminate human error. Naturally, there will be software errors, but these are more easily fixed than the human nature.

After receiving a critical mass of information, the car should be able to make decisions and function within the parameters is has been previously given. However, not even self-driving cars are safe from the unexpected.