PhySense: Defending Physically Realizable Attacks for Autonomous Systems via Consistency Reasoning

Autonomous vehicles (AVs) empowered by deep neural networks (DNNs) are bringing transformative changes to our society. However, they are generally susceptible to adversarial attacks, especially physically realizable perturbations that can mislead perception and cause catastrophic outcomes. While existing defenses have shown success, there remains a pressing need for improved robustness while maintaining efficiency to meet real-time system operations.

To tackle these challenges, we introduce PhySense, a complementary solution that leverages multi-faceted reasoning for misclassification detection and correction. This defense is built on physical characteristics, including static and dynamic object attributes and their interrelations. To effectively integrate these diverse sources, we develop a system based on the conditional random field that models objects and relationships as a spatial-temporal graph for holistic reasoning on the perceived scene. To ensure the defense does not violate the timing requirement of the real-time cyber-physical control loop, we profile the run-time characteristics of the workloads to parallelize and pipeline the execution of the defense implementation. The efficacy of PhySense is experimentally validated through simulations of datasets and real-world driving tests. It also demonstrates resiliency against adaptive attacks, and the potential of applying underlying principles to other modalities beyond vision.