Abstract
Artificial Intelligence (AI) is increasingly being integrated into modern Safety-Critical systems running AI algorithms, such as lightweight Convolutional Neural Networks (CNNs), which enable a wide range of autonomous functionalities, including object recognition, scene understanding, trajectory prediction, and decision making.
Recent advances in semiconductor technologies have further accelerated this trend by enabling the integration of dedicated AI accelerators directly within autonomous control platforms (i.e., at the edge), which reduces the CNN response latency. Nevertheless, the scaling of technology nodes toward 7 nm and below makes edge devices increasingly vulnerable to hardware reliability issues (caused for example by manufacturing defects and premature device degradation), which may ultimately manifest as Soft Errors at the application level, silently corrupting intermediate computations. Such faults can alter internal activations, and modify the final CNN output during inference, resulting in incorrect control decisions, or even catastrophic accidents involving human lives. Therefore, effective application-level monitoring mechanisms are required to promptly identify anomalous NN behavior, meeting the resource constraints while enabling the activation of recovery strategies before the fault causes severe consequences.
Although existing solutions demonstrated promising results in detecting faults, they generally analyze each inference independently, treating each NN inference as an isolated event, which, in real-world deployments, neglects the sequential nature of the sensory observations processed by the autonomous system.
Indeed, in real deployments, CNN process sequential input observations (i.e., images), often producing repeated outcomes over time. This work introduces a fault detection mechanism that, at each inference, evaluates both current and recent outcomes within a time window to determine the presence of faults.
Specifically, the proposed detection mechanism relies on an auxiliary lightweight Multi-Layer Perceptron (MLP) trained to replicate the same behavior of the reference CNN model by processing statistical measurements computed on the output of the first convolutional layer. During the operational phase, both neural networks (the original one and the MLP operate in parallel) produce inference results that are later used to compute the level of agreement. Such an agreement is calculated by comparing the inference outcomes across the time window of observations. In the end, a fault is detected when the level of agreement between the MLP and the main CNN drops under a predefined threshold.
It is worth noting that the proposed method requires no hardware changes and can be deployed on pre-trained models, and it can be trained through knowledge distillation. Moreover, the experimental results gathered on a set of representative CNNs and datasets show that the detection system maintains a false positive rate of no more than 7.33%, and additionally, it can correctly identify faulty cases up to 97.79%.