In our last post, we explained details of our Driver Out runs, including the advanced driving capabilities of our TuSimple Driver, and the setup we chose to ensure operational safety. Another important element of safety is optimizing the reliability of the autonomous truck.
The world’s most safety-critical technologies and systems like spacecraft, power grids, and medical devices maximize safety and minimize failure risks by designing for reliability.
There are two approaches to increase overall system reliability:
We used these techniques to design our solution for autonomous trucks.
This approach is often referred to as the “Swiss cheese” model of reliability. Like Swiss cheese, a single layer of the system may have“holes”. Nevertheless, when layers are stacked on top of each other, individual gaps are covered by the protections of the other layers. Individually there may be gaps. As a set, you attain improved coverage.
Class 8 trucks, including the Navistar International LT that we use in our autonomous truck solution, have both highly reliable subsystems and an array of redundancies. For example, each load-bearing axle has four wheels, two on each side. If one tire blows, the others are still able to carry the full load. Likewise, over-specifying the steering column makes it very unlikely to fail over the lifetime of the truck.
Traditionally, Class 8 trucks include the driver as one of the layers of redundancy. For example, if the power steering fails, in most cases the driver could still muscle the steering wheel to pull the truck over. With the TuSimple autonomous driver, we’ve added redundancies in hardware, software, and algorithms to ensure we maintain the capability to handle such events safely.
Establishing a highly reliable system was paramount prior to conducting the Driver Out runs. The existing highly reliable and redundant systems in the Navistar International LT, together with the additional redundant systems retrofitted to the trucks, protect against rare but important equipment failures. Implementing these systems was a critical step that enabled the world’s first fully autonomous Driver Out runs on open public roads. For more information about our approach to safety, please refer to our Driver Out Safety Framework.