Accurate power time-series prediction is an important application for building new industrialized smart cities. The gated recurrent units (GRUs) models have been successfully employed to learn temporal information for power time-series prediction, demonstrating its effectiveness. However, from a statistical perspective, these existing models are geometrically ergodic with short-term memory that causes the learned temporal information to be quickly forgotten. Meanwhile, these existing approaches completely ignore the temporal dependencies between the gradient flow in the optimization algorithm, which greatly limits the prediction accuracy. To resolve these issues, we propose a novel GRU model coupling two new mechanisms of selective state updating and adaptive mixed gradient optimization (GRU-SSU-AMG) to improve the accuracy of prediction. Specifically, a tensor discriminator is used for adaptively determining whether hidden state information needs to be updated at each time step for learning the extremely fluctuating information in the proposed selective GRU (SGRU). In addition, an adaptive mixed gradient (AdaMG) optimization method that mixes the moment estimations is proposed to further improve the capability of learning the temporal dependencies information. The effectiveness of the GRU-SSU-AMG has been extensively evaluated on five different real-world datasets. The experimental results show that the GRU-SSU-AMG achieves significant accuracy improvement compared with the state-of-the-art approaches.

Depth-map estimation reflects the geometry of the visible surface in the environment directly and plays an important role in perception and decision for intelligent robots. However, sparse LiDAR only provides low-resolution depth information, which is a huge challenge for accurate sensing algorithms. To address this problem, this article proposes a novel fusion framework to generate dense depth-map based on event camera and sparse LiDAR. The approach uses the geometric information provided by the point cloud as prior knowledge and clusters point cloud data by an improved density clustering algorithm. Combined with the 3-D surface model of each cluster, the approach can provide 3-D reconstructions of the coordinate points of events and further obtain the dense-depth map by depth expansion and hole filling. Finally, we deploy our approach in MVSEC datasets and real-world applications. Experimental results show that, compared with other approaches, our approach can obtain more accurate depth information.

Depth estimation from stereo images is essential to many applications such as robotics and autonomous vehicles, most of which ask for the real-time response, high energy and storage efficiency. Recent work has shown deep neural networks (DNN) perform extremely well for stereo estimation. However, these state-of-the-art DNN based algorithms are challenging to be deployed into real-world applications due to the high computational complexities of DNNs. Most of them are too slow for real-time inference and require several seconds of GPU computation to process image frames. In this article, we address the problem of fast stereo estimation and propose an efficient and light-weighted stereo matching system, called StereoBit, to produce a disparity map in a real-time manner while achieving close to state-of-the-art accuracy. To achieve this goal, we propose a binary neural network to generate weighted Hamming distance for an efficient similarity join in stereo estimation. In addition, we propose a novel approximation approach to derive StereoBit network directly from the well-trained network with the cosine similarity. Our approximation strategies enable a significant speedup while maintaining almost the same accuracy compared to the network with the cosine similarity. Furthermore, we present an optimization framework for fully exploiting the computing power of StereoBit. The framework provides a significant speedup of stereo estimation routines, and at the same time, reduces the memory usage for storing parameters. The effectiveness of StereoBit is evaluated by comprehensive experiments. StereoBit can achieve 60 frames per second on an NVIDIA TITAN Xp GPU on KITTI 2012 benchmark while achieving 3-pixel non-occluded stereo error 3.56 percent.

Point clouds from 3-D light detection and ranging (LiDAR) are useful for roadside units (RSU) applications in intelligent transportation system (ITS). High-density LiDAR products are restricted by high cost while the low-density and cheap ones are usually insufficient to perceive. Event-based cameras react to the changes in light intensity and output dense event streams consisting of triggered pixels. Unfortunately, there currently lacks depth information for event cameras. In order to address these problems, this article presents an approach to enhance sparse 3-D LiDAR point clouds with event pixels from an event-based camera. In our approach, the depth values of event pixels are estimated based on the distribution models which they belong to. The distribution models of event pixels are determined by the spatial information of the neighboring LiDAR points in a structural manner which we called the physical structure. To verify our approach, we conduct several real-world experiments about RSU applications in ITS. Results demonstrate that our approach can effectively improve 3-D point clouds density. The average accuracy of 3-D and 2-D vehicle detection increase by a factor of 14.6 and 8.8, respectively.

3D object detection is a critical task in the field of robotics and autonomous driving. Although recent LiDAR-based 3D object detection techniques have been well-studied and achieve high detection accuracy, the cost of the LiDAR sensor itself proposes a high premium for its practical implementation. Recently introduced Pseudo-LiDAR based methods that utilize image data to detect 3D information show great prospects for their high cost-effectiveness. However, existing Pseudo-LiDAR methods tend to be intensive computations for the adaption of complex stereo matching algorithms, and therefore can not meet the real-time requirement. To tackle this issue, we propose a lightweight Pseudo-LiDAR 3D detection system that achieves both high accuracy and high responsiveness. Specifically, we adopt a highly efficient depth estimator with Binary Neural Networks (BNNs) to exploit timely depth prediction. To mitigate the accuracy degradation issue caused by the quantization of the BNNs, we introduce several promoting schemes into the depth estimation procedure, including continuous depth approximation, geometric constraints of virtual planes, and training scope restriction, to enhance its performance. Moreover, we further provide an in-depth analysis to the architecture of 3D detector orienting to the Pseudo-LiDAR task and develop effective modules to gain solid accuracy improvement while maintaining low runtime demand. Experiments on the KITTI benchmark and online leaderboard show that our system can conduct the 3D detection within a mere 36 ms, while simultaneously achieving competitive results when compared to the state-of-the-art algorithms.