Mobile charging is feasible to deal with the energy-constrained problem in wireless rechargeable sensor networks (WRSNs). The mobile chargers (MCs) are usually employed to charge the sensors sequentially according to the charging schemes. Existing studies assume that each sensor should be charged to its maximum energy capacity or to a fixed upper threshold before the next one can be charged. However, they neglect to control the charging time adaptively of each sensor according to the charging demand. Hence, in this paper, we assume that the charging time of each sensor can be controlled, and we study the joint optimization of charging sequence and charging time problem (JCSCT). Correspondingly, we propose a novel deep reinforcement learning with hybrid action space approach for JCSCT (DRLH-JCSCT), which utilizes deep q-network (DQN) to generate the charging sequence, and adopts deep deterministic policy gradient (DDPG) to determine the charging time. An attention-based encoder–decoder model is integrated in the actor network of DDPG, and a modified bi-directional gate recurrent unit network (MBGRU) is utilized as the decoder. We also design a novel reward function to evaluate the quality of the charging actions. Simulations demonstrate the improved charging performance of the proposed approach, with a longer network lifetime and fewer failed sensors compared with the existing mobile charging scheduling approaches.

The inverse calculation of burden distribution matrix (BDM) is one of the most important challenges in the blast furnace iron-making processes. Focusing on this practical challenge, this paper proposes a new burden distribution spatial model in burden charging process, and develops a B-spline approximation-based probability density function (PDF) control algorithm to assign the expected thickness distribution of burden layer and perform the required inverse calculation of BDM. First, a novel method for the thickness distribution of burden layer is given using B-spline model. Then, according to the coexistence of continuous and bounded discrete variables in BDM, a novel hybrid optimization control method by combining integer programming and PDF tracking is further established. Finally, the proposed PDF-based iterative inverse calculation of BDM using B-spline models are tested using industrial data. The simulation results show that the proposed method is well-suited to solve the BDM inverse calculation problem in practice.

In this paper, an intelligent data-driven optimization scheme is proposed for finding the proper burden surface distribution, which exerts large influences on keeping blast furnace running smoothly in an energy-efficient state. In the proposed scheme, production indicators prediction models are first developed using a kernel extreme learning machine algorithm. To heel, burden surface decision is presented as a multiobjective optimization problem for the first time and solved by a modified two-stage intelligent optimization strategy to generate the initial setting values of burden surface. Furthermore, considering the existence of the approximation error of the created prediction models, feedback compensation is implemented to enhance the reliability of the results, in which an improved association rule mining method is developed to find the corrected values to compensate the initial setting values. Finally, we apply the proposed optimization scheme to determine the setting values of burden surface using actual data, and experimental results illustrate its effectiveness and feasibility.

Deploying the sensor nodes at the best locations for random field reconstruction via sensor network is a fundamental task. One-dimensional random field is a stochastic process. In this paper, we first propose an optimal sensor deployment strategy for Wiener process estimation. The optimal locations for the deployed sensors are uniformly distributed in the field. In addition, we propose a suboptimal sensor deployment to estimate the Gaussian random field which is described as an Ornstein-Uhlenbeck process. We show that the suboptimal deployment strategy for Gaussian random field is also uniformly distributed. Several simulations show the performance of our proposed deployment strategies.

This paper exploits optimal position of the mobile sensor to improve the target tracking performance of wireless sensor networks and simultaneously localize both of the static sensor nodes and mobile sensor nodes when tracking the human motion. In our approach, mobile sensors collaborate with static sensors and move optimally to achieve the required detection performance. The accuracy of final tracking result is then improved as the measurements of mobile sensors have higher signal-to-noise ratios after the movement. Specifically, we can simultaneously localize the mobile sensor and static sensors position when localizing the human's position based on augmented extended Kaiman filters (EKF). In the algorithm, we develop a sensor movement optimization algorithm that achieves near-optimal system tracking performance. We also presented an sensor nodes management scheme in order to deduce the computation complexity when localizing the static sensor nodes. The effectiveness of our approach is validated by extensive simulations.

Most of the target tracking algorithms proposed for wireless sensor networks (WSNs) so far have been relying on sensors of single modality. To integrate multiple sensing modalities (e.g., by using the proximity sensors and ranging sensors together) to improve the tracking performance, the tracking algorithm shall be capable to deal with non-linear and non-Gaussian nature of the tracking problem. In this paper, we present a particle filter algorithm for multi-modality target tracking in WSNs. Simulation results show that the proposed algorithm can provide a good balance among sensor costs and tracking accuracy.

We propose a novel entropy-based method for feature selection in order to reduce the computational burden for real time simultaneous localization and map building (SLAM) for mobile robot navigation. Our approach is based on information (entropy) theory together with a data association method to initialize new features into the map, match measurements to the map features, and remove out-of-date features. The selected features are optimum in the sense that fusion of measurements from those features with existing information would yield the most entropy reduction in estimating the robot location and the map features' locations. Our method has the advantage of selecting a suitable number of features by considering the computational constraint in real time implementations. Simulation results show that the proposed entropy based feature selection strategy is effective in dealing with the map scaling problem in SLAM.

In this paper a feature detection algorithm based on a new curve gradient model is proposed for simultaneous localization and mapping (SLAM) for complex outdoor environments. The curve gradient model is derived for data segmentation and has the advantage of being suitable for segmentation of data from various types of feature such as point feature and circular feature. The real time implementation of SLAM together with this feature extraction algorithm is realized by using a combination of odometry and laser scanner data. The system was tested on a long walk way at Nanyang Technological University. The experimental results show that the feature detection algorithm performs well during SLAM.

In this paper we present a new approach for natural feature extraction using a laser scanner for the purpose of localization in outdoor environments. In semi-structured outdoor environments, naturally predominant features such as trees and edges are considered. The proposed method applies a batch processing which carries out feature extraction after measurements from a full scan are received. The algorithm consists of data segmentation and parameter acquisition. A modified Gauss-Newton method is proposed for fitting circle parameters iteratively. The natural features extracted through this approach are more robust than those obtained by existing methods. In order to reduce the estimation error caused by the linearization in the extended Kalman filtering (EKF), a particle filter is applied to realize the prediction and validation by integrating data from both the laser range sensor and encoder in outdoor environments. The proposed feature extraction and localization algorithms are verified in a real world experiment.

We present an efficient integer programming (IP) based data association approach to simultaneous localization and mapping (SLAM). In this approach, the feature based SLAM data association problem is formulated as a 0-1 IP problem. The IP problem is approached by first solving a relaxed linear programming (LP) problem. Based on the optimal LP solution, a suboptimal solution to the IP problem is then obtained by applying an iterative heuristic greedy rounding (IHGR) procedure. Unlike the traditional nearest-neighbor (NN) algorithm, the proposed algorithm deals with a global matching between existing features and measurements of each scan and is more robust for an environment of high density features which is usually the case in outdoor environments. We provide a simulation study where the NN algorithm fails whereas our proposed algorithm performs satisfactorily. Experimental results also demonstrate the effectiveness and efficiency of our approach.