General Motors’ driverless subsidiary Cruise has recalled 300 of its vehicles after one of its “robotaxis” bumped into a bus in San Francisco.

In a blog post, Founder and CEO Kyle Vogt has written how there was a minor collision after a city bus slowed and the AV was late to brake behind it. It resulted in minor damage to the front bumper of the AV and caused no injuries.  

“Fender benders like this rarely happen to our AVs, but this incident was unique,” he wrote. “We do not expect our vehicles to run into the back of a city bus under any conditions, so even a single incident like this was worthy of immediate and careful study.”

He explains that, “We quickly determined the bus’s behavior was reasonable and predictable. It pulled out into a lane of traffic from a bus stop and then came to a stop. Although our car did brake in response, it applied the brakes too late and rear-ended the bus at about 10 mph. We identified the root cause, which was a unique error related to predicting the movement of articulated vehicles (i.e. vehicles with two sections connected by a flexible joint, allowing them to bend in the middle) like the bus involved in this incident.”

He says once his team understood the root cause, engineering teams immediately started creating a software update that would significantly improve performance near articulated vehicles. Once that work was completed, tested, and validated, the operations team rolled the change out to the fleet. This work was completed within two days of the incident occurring. “The results from our testing indicated that this specific issue would not recur after the update,” he says.

You can read the full blog post here.

(File picture – Cruise)