Efficient diverse redundant DNNs for autonomous driving

Automotive applications with safety requirements must adhere to specific regulations such as ISO 26262, which imposes the use of diverse redundancy for the highest integrity levels (i.e., ASIL D). While this has been often achieved by means of Dual-Core LockStep (DCLS) for microcontrollers, it remains an open challenge how to realize diverse redundancy efficiently, i.e., without full duplication and preserving performance, for DNN-based safety-related tasks, such as object detection, needing accelerators for performance reasons.This paper proposes an architecture where the accelerator performing DNN inference is replicated, as in the case of DCLS for cores, but using a cheaper implementation for the replica. In particular, we build on the stochastic nature of DNN-based object detection to realize two redundant accelerators where the secondary accelerator uses smartly chosen lower precision arithmetic (e.g., dropping some bits of the original data) so that it provides diverse redundancy, it can keep the performance of the primary accelerator, does not require as much cost as full- precision replication, and can build on the very same data stream from memory used by the primary accelerator. With a simple heuristic, we show that such a diverse redundancy scheme is able to cope with faults restricting false positives and negatives to a few relatively small objects.
The research leading to these results has received funding from the European Union’s Horizon Europe Programme under the SAFEXPLAIN Project (www.safexplain.eu), grant agreement num. 101069595. This work has also been partially supported by the Spanish Ministry of Science and Innovation under grant PID2019-107255GBC21/AEI/10.13039/501100011033.
Peer Reviewed
Postprint (author's final draft)