Embedded Graph Convolutional Networks for Real-Time Event Data Processing on SoC FPGAs

The utilisation of event cameras represents an important and swiftly evolving trend aimed at addressing the constraints of traditional video systems. Particularly within the automotive domain, these cameras find significant relevance for their integration into embedded real-time systems due to lower latency and energy consumption. One effective approach to ensure the necessary throughput and latency for event processing systems is through the utilisation of graph convolutional networks (GCNs). In this study, we introduce a series of hardware-aware optimisations tailored for PointNet++, a GCN architecture designed for point cloud processing. The proposed techniques result in more than a 100-fold reduction in model size compared to Asynchronous Event-based GNN (AEGNN), one of the most recent works in the field, with a relatively small decrease in accuracy (2.3% for N-Caltech101 classification, 1.7% for N-Cars classification), thus following the TinyML trend. Based on software research, we designed a custom EFGCN (Event-Based FPGA-accelerated Graph Convolutional Network) and we implemented it on ZCU104 SoC FPGA platform, achieving a throughput of 13.3 million events per second (MEPS) and real-time partially asynchronous processing with a latency of 4.47 ms. We also address the scalability of the proposed hardware model to improve the obtained accuracy score. To the best of our knowledge, this study marks the first endeavour in accelerating PointNet++ networks on SoC FPGAs, as well as the first hardware architecture exploration of graph convolutional networks implementation for real-time continuous event data processing. We publish both software and hardware source code in an open repository: https://github.com/vision-agh/*** (will be published upon acceptance).