Deep-RBF Networks for Anomaly Detection in Automotive Cyber-Physical Systems

TL;DR

This paper introduces deep-RBF networks that unify control and anomaly detection in automotive CPS, effectively identifying adversarial and OOD inputs without extra resources, demonstrated on real-world datasets and hardware testbeds.

Contribution

It extends deep-RBF networks to regression tasks in automotive CPS, enabling simultaneous control and anomaly detection within a single network architecture.

Findings

Deep-RBF networks detect adversarial attacks effectively.

They operate with low resource overhead.

Validated on hardware CPS and real-world datasets.

Abstract

Deep Neural Networks (DNNs) are popularly used for implementing autonomy related tasks in automotive Cyber-Physical Systems (CPSs). However, these networks have been shown to make erroneous predictions to anomalous inputs, which manifests either due to Out-of-Distribution (OOD) data or adversarial attacks. To detect these anomalies, a separate DNN called assurance monitor is often trained and used in parallel to the controller DNN, increasing the resource burden and latency. We hypothesize that a single network that can perform controller predictions and anomaly detection is necessary to reduce the resource requirements. Deep-Radial Basis Function (RBF) networks provide a rejection class alongside the class predictions, which can be utilized for detecting anomalies at runtime. However, the use of RBF activation functions limits the applicability of these networks to only classification tasks. In this paper, we show how the deep-RBF network can be used for detecting anomalies in CPS regression tasks such as continuous steering predictions. Further, we design deep-RBF networks using popular DNNs such as NVIDIA DAVE-II, and ResNet20, and then use the resulting rejection class for detecting adversarial attacks such as a physical attack and data poison attack. Finally, we evaluate these attacks and the trained deep-RBF networks using a hardware CPS testbed called DeepNNCar and a real-world German Traffic Sign Benchmark (GTSB) dataset. Our results show that the deep-RBF networks can robustly detect these attacks in a short time without additional resource requirements.