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Tesla Electric Steering Redundancy

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As I understand it, there is one brushless electric motor driving the steering with a toothed belt. There are two independently powered controllers that feed the motor. Brushless motors can last a long time and perhaps the controllers can sense degradation in the motor before it fails but there is still only one belt and it seems like it will always be operating at the same places on the belt unlike a timing belt which rotates continuously. Level 4 and 5 autonomous driving should require "fail-operational" capability which means safe operation will continue in the presence of any component failure. Perhaps motor degradation will be dealt with properly but I worry about the belt. Maybe they will require mandatory replacement after certain time in service before autonomous driving will continue to be enabled. Thoughts?
 
Level 4 and 5 autonomous driving should require "fail-operational" capability which means safe operation will continue in the presence of any component failure.

Why do you say that? Why does it need any more redundancy than a human driving a vehicle?

How far are you going to take it? Do you need a second battery? Duplicate wheel bearings? Duplicate cameras at each spot? Duplicate brake master cylinders? etc.
 
The 3 and Y were designed from the get-go to be autonomous. That center landscape screen is for en-route entertainment. Brakes have had redundancy for decades and you don't have complete failures suddenly. There are three front cameras which are the most important and two self checking driving computers. There are two sources of 12 vdc for the electronics, the 12 vdc battery and a DC to DC converter. Wheel bearing failures do not suddenly disable a car. We need more redundancy than humans because humans are not safe enough. There should be enough redundancy so that the car can stop safely off the road when a significant failure occurs. It already can stop safely in the road and turn on the emergency flashers if it thinks you've died when on autopilot. Hundreds if not thousands of parameters are monitored continuously in these cars. I was an airline pilot who flew aircraft that were "fail-operational" during autopilot landings. An engine, electrical bus, generator, autopilot, computer or a hydraulic system could fail during a landing and the landing completed or successfully aborted. They have been doing auto-landings for over 50 years. Autonomous driving is harder but aborting to the side of a road perhaps easier. The steering drive belt seems to be a mechanical component that might be a weak link.