ORCHARD: Visual object recognition accelerator based on approximate in-memory processing

Yeseong Kim, Mohsen Imani, Tajana Rosing

Abstract: In recent years, machine learning for visual object recognition has been applied to various domains, e.g., autonomous vehicle, heath diagnose, and home automation. However, the recognition procedures still consume a lot of processing energy and incur a high cost of data movement for memory accesses. In this paper, we propose a novel hardware accelerator design, called ORCHARD, which processes the object recognition tasks inside memory. The proposed design accelerates both the image feature extraction and boosting-based learning algorithm, which are key subtasks of the state-of-the-art image recognition approaches. We optimize the recognition procedures by leveraging approximate computing and emerging non-volatile memory (NVM) technology. The NVM-based in-memory processing allows the proposed design to mitigate the CMOS-based computation overhead, highly improving the system efficiency. In our evaluation conducted on circuit- and device-level simulations, we show that ORCHARD successfully performs practical image recognition tasks, including text, face, pedestrian, and vehicle recognition with 0.3% of accuracy loss made by computation approximation. In addition, our design significantly improves the performance and energy efficiency by up to 376x and 1896x, respectively, compared to the existing processor-based implementation.