The Tesla Model 3 is the newest and most inexpensive model in the Tesla lineup, and while it lacks some of the features found in the more expensive Model S and Model X, it may end up exceeding them on the self-driving technology front. How? One document appears to reveal an intriguing clue: redundant steering motors, which brings it one step closer to a level of automation where the driver is not required to monitor the driving environment.
Tesla has planned for the Model 3 to deploy self-driving technology in the future with an optional $3,000 “Full Self-Driving” package, which can be added on top of the $5,000 Enhanced Autopilot package. But that package received criticism for being offered with the disclaimer that it is “dependent upon extensive software validation and regulatory approval, which may vary by jurisdiction.” Still, the recently released Model 3 Emergency Response Guide, gives us a hint on how they could get closer, from a hardware perspective, to accomplishing that.
The Emergency Response Guide is a standard document made available for most cars on the market to help first responders with things like how they can shut down or cut into a car. In the Model 3's case, though, the guide is seemingly a bit more revealing, showing where the high-voltage components are along with the location of all of the strengthened steel, in addition to what look like redundant steering motors.
Here, we see a drivetrain diagram on the “Drive Unit” page which shows the steering rack in front. This depiction also shows what appears to be Tesla’s first production implementation of redundant steering motors with fully independent electrical circuits. That’s a significant improvement over the Model S and X racks, as each of those use a single motor unit. The single motor unit does not provide any direct redundancy which could limit those models to SAE Level 2 automation, which would always require the driver to monitor the car. (A spokeswoman for Tesla did not immediately respond to a request for comment; we’ll update this post if we hear back.)
The Model 3 implementation, though, could help it get to SAE Level 3 automation or above, and is one of the only parts where the Model 3 is more advanced than its higher-end siblings. Although this is the first production implementation that I have spotted, it is important to note that Volvo has also implemented some redundancy in the S90 steering rack by using dual independent windings according to a report by IEEE Spectrum.
Independent windings work in a similar manner to dual motors but also may be installed on the same shaft, depending on the implementation. Another method of indirect redundancy uses the brake system, in which the system pump can cycle an individual wheel to control the direction of the car in case of steering failure; it’s unclear, though, whether such a system would be enough for Level 3 automation or above.
General Motors has recently stated that they have produced around 130 autonomous Chevy Bolt EVs, which appear to be at Level 4 of automation based on their description. But a check of the parts diagrams shows a column-mounted steering motor that appears to have no direct redundancy. They might be modifying the configuration for the autonomous cars and installing a different motor setup, or relying on the brakes for indirect redundancy which could make the Model 3 superior when it comes to steering safety.
While the redundant rack on the Model 3 is a big step in the right direction, there are many other hardware and software components that still need to be fully developed in order to implement automation at a level where the driver can be fully hands-off—and maybe take a nap.
Bozi was born in the land of the Yugo but grew up flipping Chevys in the Southeast US. His automotive background ranges from running a used car sales and service facility to building junkyard LS engines and fixing endurance cars. You can find him on Twitter and YouTube.