FPGA-based object detection processor with HOG feature and SVM classifier

Computer vision is an important sensing technique to translate the information to decisions. In robotic applications, object detection is a critical skill to perform tasks for robots in complex environments. The deep-learning framework, e.g. You Only Look Once (YOLO), attracts much more attention recently. Moreover, it is not an optimal solution for a mobile robot since it requires a large scale of hardware resources, on-chip SRAMs, and power consumption. In this work, we report an object detection processor synchronizing the image sensor in FPGA with a cellbased histogram of oriented gradient (HOG) feature descriptor and support vector machine (SVM) classifier by parallel sliding window mechanism. The HOG feature extraction circuitry with pixel-based pipelined architecture constructs the cell-based feature vectors for parallelizing partial SVM-based classification in multiple sliding windows. The SVM classification produces the final result after accumulating the vector components in one sliding window. This framework can be used to both localize and recognize multiple objects in video footage. The proposed object processor, in which the SVM classifier is trained by INRIA datasets, is implemented and verified on Intel Stratix IV FPGA for the pedestrian.