MBBNet: An Edge IoT Computing-based Traffic Light Detection Solution for Autonomous Bus

Abstract Traffic light detection is a key module in the autonomous driving system to enhance the interactions between drivers and unmanned vehicles. In recent studies, deep neural networks are widely used for traffic light detection and resource/power consumption is a major concern for model deployment in vehicular edge devices. This paper proposes a novel light-weight deep CNN model that integrates the multi-backbone of state-of-the-art architectures for the self-driving traffic light detection. The MBBNet (Multi-BackBone Network) consists of three common convolutional backbones, i.e., the normal, residual and highway (DenseNet) convolutional modules. Simple ensemble of those backbones may incur high computational load. Therefore, channel compression is adopted to control the model parameters, while guaranteeing the accuracy for mobile and embedded hardware. Evaluation of a dataset collected from real road conditions demonstrate the robustness of our detection system, and it achieves higher accuracy (accuracy > 0.94 and A v e r a g e _ I O U > 74.05 % ) for self-driving buses. In terms of resource consumption, the trained model size is 1.35 MB, and can process high-resolution images (1280 × 960) at 14 FPS (frames per second) on low-power edge devices.