I own the same model of vehicle as Waymo is using (2017 Pacifica PHEV). It's cool to see how little they've had to visibly modify the car (apart from the sensors)—the interior looks 100% stock, other than the row of buttons on the ceiling. Given the level-1 autonomous features in the vehicle (self-parking, etc.), all of the integrations are probably done over CAN-bus, with no additional hardware required (again, apart from the sensors and the computing power).
I think there's more than that. The safety report they released recently indicates the vehicles also have redundant power systems, redundant braking systems, redundant steering systems, etc. I doubt that the stock configurations require as much redundancy.
Ah, that could be. Though could that be talking about redundant processing (i.e. two dependent algorithms making the same decision) rather than duplicate hardware?
For example: The steering system features a redundant drive motor system with independent controllers and separate power supplies. Either one can manage steering in the case that a failure occurs in the other
