Yesterday we had our first (and hopefully our last!) small accident with our autonomous vehicles. We were just at the end of a highly successful driving session (165Km): the guys in charge of the autonomous vehicle (the follower) stopped the vehicle just behind the leader, and got off the vehicle. They disengaged the perception system, but unfortunately they forgot to disengage the x-by-wire and planning systems (well, both of them thought it was the other guy who disengaged everything and got off to relax).
Suddenly the vehicle started moving towards the vehicle in front (with no perception, only GPS waypoints were used) and the follower hit the leader. Luckily it was a slow speed hit and everybody was away since the vehicles were parked, but the chassis got some little damages. The frontal sensors were protected by the bull bar, so no damage and no miscalibration occurred, but now the leader has a small dent in the back part. We don’t know whether to fix it or not: after all this is part of history anyway!
Well, in these cases, there’s no e-stop or other mechanism that can avoid this, since everybody thought everything was disengaged and were relaxing away form the vehicles. This showed a design problem: we should have a very visible device (like a light or something like that) which is on whenever the autonomous driver is engaged.