In its latest monthly update about its autonomous car project, Google has laid out how it taught its autonomous cars appropriate honking behaviour.
According to the development team, "the human act of honking may be (performance) art, but our self-driving cars aim to be polite, considerate, and only honk when it makes driving safer for everyone".
Firstly, the team had to teach its cars the situations in which its useful and polite to honk, like "when a driver begins swerving into our lane or backing out of a blind driveway".
Then they had to eliminate false positives, and program the vehicle to distinguish between regular situations and dangerous ones, such as the difference between another car performing a u-turn and one that's about to drive onto the wrong side of the road.
During the initial testing phase, development vehicles would only play their horns internally, so engineers could score and fine tune the system without irking other road users.
Since the team allowed the automated honking system to use the car's real horn, it has refined how the electronic driving software uses the horn. For example, while two friendly pips of the horn may be sufficient if someone is reversing towards the autonomous vehicle, in emergency situations the system is configured to continuously honk until the situation has passed.