Weidong Chen

Shanghai Jiao Tong University, Shanghai, Shanghai Shi, China

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Publications (146)83.47 Total impact

  • Zhixuan Wei · Weidong Chen · Jingchuan Wang · Huiyu Wang
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    ABSTRACT: This paper presents a new navigation system designed for the smart wheelchair, which interacts with a human user using a low throughput interface. Through the low throughput interface, the user can only give a very limited number of command types with a low frequency, meaning that a low throughput interface requests the user to do more steps, taking a longer time, just to select the desired goal. In order to decrease the number of operations requested to the user, our navigation system is designed to refine the alternative targets by selecting the significant targets and organize them in a binary tree for reducing user’s operation. We also introduce a user-friendly visual feedback to display to the user in order to show the current state and the prompt commands to the user, too. This navigation system is successfully tested in a real environment.
    No preview · Article · Jan 2016
  • Zhe Liu · Weidong Chen · Junguo Lu · Hesheng Wang · Jingchuan Wang

    No preview · Article · Jan 2016 · IEEE Transactions on Control Systems Technology
  • Zhe Liu · Hesheng Wang · Weidong Chen · Junzhi Yu · Jian Chen

    No preview · Article · Jan 2016 · IEEE Transactions on Intelligent Transportation Systems
  • Hesheng Wang · Yinping Lai · Weidong Chen · Qixin Cao
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    ABSTRACT: Robot motion planning is a fundamental problem to ensure the robot executing the task without clashes, fast and accurately in a special environment. In this paper, a motion planning of a 12 DOFs remote handling robot used for inspecting the working state of the ITER-like vessel and maintaining key device components is proposed and implemented. Firstly, the forward and inverse kinematics are given by analytic method. The work space and posture space of this manipulator are both considered. Then the motion planning is divided into three stages: coming out of the cassette mover, moving along the in-vessel center line, and inspecting the D-shape section. Lastly, the result of experiments verified the performance of the motion design method. In addition, the task of unscrewing/screwing the screw demonstrated the feasibility of system in function.
    No preview · Article · Dec 2015 · Fusion Engineering and Design
  • Source
    Xi Chen · Weidong Chen
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    ABSTRACT: In through wall radar sensing, the wall parameters estimation (WPE) problem has been a topic that attracts a lot of attention since the wall parameters, i.e., the permittivity and the thickness, are of crucial importance to locate the targets and to produce a well-focused image, but they are usually unknown in practice. To solve this problem, in this paper, the support vector regression (SVR), a powerful tool for regression analysis, is introduced, and its performance on WPE, provided it is used it in the regular way, is investigated. Unfortunately, it is shown that the regular use of SVR cannot afford satisfactory estimation results since the sample data used in SVR, namely the received echoes from the walls, are seriously interfered with the echoes from the targets which are located near the walls. In view of this limitation, a novel SVR-based WPE approach that consists of three stages is proposed by this paper. In the first stage, three regression functions are trained by SVR, one of which will output the estimate of the permittivity in the second stage, and the others are designed to output two instrumental variables for estimating the thickness. In the third stage, the estimate of thickness will be achieved by minimizing a predefined cost function wherein the estimated permittivity and the outputted instrumental variables are involved. The better robustness and higher estimation accuracy of the proposed approach compared to the regular use of SVR are validated by the numerical experimental results using finite-difference time-domain simulations.
    Preview · Article · Nov 2015 · Journal on Advances in Signal Processing
  • Xinwu Liang · Hesheng Wang · Weidong Chen · Dejun Guo · Tao Liu
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    ABSTRACT: In this paper, the uncalibrated image-based trajectory tracking control problem of wheeled mobile robots will be studied. The motion of the wheeled mobile robot can be observed using an uncalibrated fixed camera on the ceiling. Different from traditional vision-based control strategies of wheeled mobile robots in the fixed camera configuration, the camera image plane is not required to be parallel to the motion plane of the wheeled mobile robots and the camera can be placed at a general position. To guarantee that the wheeled mobile robot can efficiently track its desired trajectory, which is specified by the desired image trajectory of a feature point at the forward axis of the wheeled mobile robot, we will propose a new adaptive image-based trajectory tracking control approach without the exact knowledge of the camera intrinsic and extrinsic parameters and the position parameter of the feature point. To eliminate the nonlinear dependence on the unknown parameters from the closed-loop system, a depth-independent image Jacobian matrix framework for the wheeled mobile robots will be developed such that unknown parameters in the closed-loop system can be linearly parameterized. In this way, adaptive laws can be designed to estimate the unknown parameters online, and the depth information of the feature point can be allowed to be time varying in this case. The Lyapunov stability analysis will also be performed to show asymptotical convergence of image position and velocity tracking errors of the wheeled mobile robot. The simulation results based on a two-wheeled mobile robot will be given in this paper to illustrate the performance of the proposed approach as well. The experimental results based on a real wheeled mobile robot will also be provided to validate the proposed approach.
    No preview · Article · Nov 2015 · IEEE Transactions on Control Systems Technology
  • Xi Chen · Weidong Chen
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    ABSTRACT: In this letter, a double-layer fuzzy fusion method is proposed to produce a higher quality image by combing multiple through-wall radar images of the same scene. The first layer is termed as intraimage fusion, in which the global and local degrees of membership are fused within each input image based on intraimage fuzzy rules. Then, in the second layer, interimage fusion is performed between input images using interimage fuzzy rules, and the output image is obtained. Compared with other fusion methods, the proposed method decreases the possibility of losing a weak target and suppresses the clutter by taking into account the local information while enhancing the target intensity values. The method also introduces a $K$-means clustering technique to automatically select the parameters of the membership functions. The performance of the proposed method is evaluated using both simulated and real experimental data.
    No preview · Article · Oct 2015 · IEEE Geoscience and Remote Sensing Letters
  • Xinwu Liang · Hesheng Wang · Yun-Hui Liu · Weidong Chen · Jie Zhao
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    ABSTRACT: A unified design method is proposed in this paper to handle adaptive visual tracking control problem of robots. In the proposed scheme, the robot dynamic parameters, camera intrinsic and extrinsic parameters and position parameters of feature points are assumed to be uncertain. A unified kinematics model is presented to simultaneously cope with kinematics modeling problem of robots with the eye-in-hand or fixed camera configuration. Based on the unified kinematics, a unified design method is proposed to solve the visual tracking control problem of robots with the eye-in-hand or fixed camera configuration. By using the depth-independent interaction matrix framework, adaptive laws are derived to handle the unknown parameters. Lyapunov stability analysis is provided to show asymptotical convergence of image position and velocity tracking errors. To show the effectiveness of the proposed unified design method, experimental results for both camera configurations are also given.
    No preview · Article · Sep 2015 · Automatica
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    ABSTRACT: In this paper, the task-space cooperative tracking control problem of networked robotic manipulators without task-space velocity measurements is addressed. To overcome the problem without task-space velocity measurements, a novel task-space position observer is designed to update the estimated task-space position and to simultaneously provide the estimated task-space velocity, based on which an adaptive cooperative tracking controller without task-space velocity measurements is presented by introducing new estimated task-space reference velocity and acceleration. Furthermore, adaptive laws are provided to cope with uncertain kinematics and dynamics and rigorous stability analysis is given to show asymptotical convergence of the task-space tracking and synchronization errors in the presence of communication delays under strongly connected directed graphs. Simulation results are given to demonstrate the performance of the proposed approach.
    No preview · Article · Sep 2015 · Cybernetics, IEEE Transactions on
  • Jingchuan Wang · Li Liu · Zhe Liu · Weidong Chen
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    ABSTRACT: In large-scale and spacious environments, keeping a reliable data association and reducing computational complexity are challenges for the implementation of Simultaneous Localization and Mapping (SLAM). Focused on these problems, a multilayer-matching-based incremental SLAM algorithm is proposed in this article. In this algorithm, SLAM is simplified as a problem composed of a least-square-based optimization problem and data association. Then, it is solved in two steps. Firstly, a multilayer matching method is applied to deal with the data-association problem. Both matching between observation and local map and matching between different local maps are carried out. The uncertainty of the results-matching is described by the Fisher information matrix. Secondly, the robot pose is optimized through an incremental QR decomposition method. This algorithm effectively avoids the local minima caused by the limited observation information, and can build a consistent map of the environment. Meanwhile, the characters (hierarchical and incremental) of the proposed algorithm ensure low computational complexity. Experiments on simulation environments and two kinds of real environments with different sparse features verify that the algorithm is applicable for real-time application in large-scale and spacious environments.
    No preview · Article · Sep 2015 · International Journal of Advanced Robotic Systems
  • Source
    Dejun Guo · Hesheng Wang · Weidong Chen · Xinwu Liang
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    ABSTRACT: This paper focuses on the problem of the adaptive image-based leader-follower formation control of mobile robot with on-board omnidirectional camera. A calibrated omnidirectional camera is fixed on the follower in any position, and a feature point representing the leader can be chosen in any position. An adaptive image-based controller without depending on the velocity of the leader is proposed based on a filter technology. In other words, only by relying on the projection of the feature on the image plane, can the follower track the leader and achieve the formation control. Moreover, an observer is introduced to estimate the unknown camera extrinsic parameters and the unknown parameters of plane, where the feature point moves, relative to omnidirectional camera frame. At last, the lyapunov method is applied to prove the uniform semiglobal practical asymptotic stability (USPAS) for the closed-loop system. Simulation results are presented to validate the algorithm.
    Preview · Article · Aug 2015 · Journal of Applied Mathematics
  • Jingchuan Wang · Ming Yang · Weidong Chen
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    ABSTRACT: According to the long length characteristics of transfer cask compared to the environment space between Tokmak Building (TB) and HCB (Hot Cell Building), this paper proposes an autonomous localization and alignment method for the internal components transportation and replacement. A localization method based on the localizability estimation is used to realize the cask's localization and navigation accurately. Once the cask arrives at the front of the TB window, the position and attitude measurement system is used to detect the relative alignment error between the seal door of pallet and the window of TB real-time. The alignment between seal door and TB window could be realized based on this offset. The simulation experiment based on the real model is designed according to the real TB situation. The experiment results show that the proposed localization and alignment method can be used for transfer cask.
    No preview · Article · Aug 2015
  • Hesheng Wang · Weidong Chen · Lifei Xu · Tao He
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    ABSTRACT: The vibration should be suppressed if it happens during the motion of a flexible robot or under the influence of external disturbance caused by its structural features and material properties, because the vibration may affect the positioning accuracy and image quality. In Tokamak environment, we need to get the real-time vibration information on vibration suppression of robotic arm, however, some sensors are not allowed in the extreme Tokamak environment. This paper proposed a vision-based method for online vibration estimation of a flexible manipulator, which is achieved by utilizing the environment image information from the end-effector camera to estimate its vibration. Short-time Fourier Transformation with adaptive window length method is used to estimate vibration parameters of non-stationary vibration signals. Experiments with one-link flexible manipulator equipped with camera are carried out to validate the feasibility of this method in this paper.
    No preview · Article · Jul 2015 · Fusion Engineering and Design
  • Li Ding · Weidong Chen · Wenyi Zhang · H. Vincent Poor
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    ABSTRACT: Multiple-input multiple-output (MIMO) radar imaging suffers from performance degradation under carrier offsets across transmitters and receivers. This paper analyzes the impact of carrier offsets on imaging a sparse target, from the perspective of the MIMO point spread function (PSF). Conditions are established for successful support recovery using orthogonal matching pursuit (OMP), and the performance loss is characterized in terms of l2 distance. A sparse imaging algorithm taking into account the perturbation due to carrier offsets is also proposed, which improves upon the OMP algorithm. Numerical experiments corroborate this analysis.
    No preview · Article · Jul 2015 · IEEE Transactions on Aerospace and Electronic Systems
  • Hesheng Wang · Weidong Chen · Yinping Lai · Tao He
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    ABSTRACT: Tokamak flexible in-vessel inspection robot is mainly designed to carry a camera for close observation of the first wall of the vacuum vessel, which is essential for the maintenance of the future tokamak reactor without breaking the working condition of the vacuum vessel. A tokamak flexible in-vessel inspection robot is designed. In order to improve efficiency of the remote maintenance, it is necessary to design a corresponding trajectory planning algorithm to complete the automatic full coverage scanning of the complex tokamak cavity. Two different trajectory planning methods, RS (rough scanning) and FS (fine scanning), according to different demands of the task, are used to ensure the full coverage of the first wall scanning. To quickly locate the damage position, the first trajectory planning method is targeted for quick and wide-ranging scan of the tokamak D-shaped section, and the second one is for careful observation. Furthermore, both of the two different trajectory planning methods can ensure the full coverage of the first wall scanning with an optimal end posture. The method is tested on a simulated platform of EAST (Experimental Advanced Superconducting Tokamak) with the flexible in-vessel inspection robot, and the results show the effectiveness of the proposed algorithm.
    No preview · Article · Jun 2015 · Fusion Engineering and Design
  • Xinwu Liang · Hesheng Wang · Y.-H. Liu · Weidong Chen
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    ABSTRACT: The adaptive image-based trajectory tracking control problem of rigid-link electrically driven (RLED) robotic manipulators is addressed in this paper. A fixed camera configuration is considered and the camera intrinsic and extrinsic parameters are assumed to be unknown. Furthermore, the manipulator dynamic and motor dynamic parameters are assumed to be uncertain and the depths of feature points can be allowed to be time varying. The depth-independent interaction matrix framework is used such that unknown parameters in the closed-loop dynamics can be parameterized linearly and adaptive laws can be derived to estimate them online. By simultaneously taking into consideration the mechanical and electrical subsystem dynamics of RLED robotic manipulators, the backstepping technique is used to design control voltage inputs to guarantee the tracking of desired image trajectories in the presence of parameter uncertainties and time-varying depth information. Asymptotical convergence of image tracking errors to zeros is proved by using Lyapunov stability theory. Simulation results based on a 3-DOFs anthropomorphic robotic manipulator are given to demonstrate the performance of the proposed adaptive visual tracking scheme.
    No preview · Article · Apr 2015
  • Jianfei Zhang · Jingchuan Wang · Weidong Chen
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    ABSTRACT: Driver assistance is one of the major tasks on smart wheelchair development. However, human following is also necessary in real application. In this paper, a control system of driver assistance and human following for smart wheelchair is presented. Driver assistance can keep the wheelchair from stairs falling and obstacle collision when the user is driving the wheelchair in complex environments with unknown obstacles. Human following can guarantee the wheelchair to follow the user with a suitable distance when the user wants to walk along by himself. The target occlusion problem caused by obstacle avoidance during human following can also be effectively solved by the use of odometry data. Both the driver assistance and human following are based on shared control strategy. And since the sensor used is ultrasound, instead of LRF, the proposed system is low-cost and can be easily implemented in real applications. The system is developed and tested on JiaoLong smart wheelchair. Experiment results show that the proposed system can improve user's driving ability in driver assistance task and it can control the wheelchair to keep a suitable distance with the target human. And it can effectively handle the target occlusion problem when it has to avoid obstacle in human following task.
    No preview · Article · Apr 2015
  • Li Ding · Weidong Chen
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    ABSTRACT: Sparse recovery algorithms with application to multiple-input-multiple-output (MIMO) radar imaging could lose their advantage under a phase mismatch among transmitter-receiver pairs. In this letter, we identify that the impact of a random phase mismatch on the imaging problem can come to a scale-down factor on the amplitude of the MIMO point spread function. We thereby establish the conditions of successful support recovery and the performance measure for the orthogonal matching pursuit (OMP) algorithm for the involved problem, both of which are functions of the scale-down factor. Meanwhile, sparse imaging via expectation-maximization (SIEM) is proposed to alleviate OMP performance loss in the face of a phase mismatch. Numerical results corroborate the analysis and illustrate the effectiveness of the SIEM algorithm.
    No preview · Article · Mar 2015 · IEEE Geoscience and Remote Sensing Letters
  • Yanlong Zhang · Weidong Chen
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    ABSTRACT: Nonparametric time-of-arrival (TOA) estimators for impulse radio ultra-wideband (IR-UWB) signals are proposed. Non-parametric detection is obviously useful in situations where detailed information about the statistics of the noise is unavailable or not accurate. Such TOA estimators are obtained based on conditional statistical tests with only a symmetry distribution assumption on the noise probability density function. The nonparametric estimators are attractive choices for low-resolution IR-UWB digital receivers which can be implemented by fast comparators or high sampling rate low resolution analog-to-digital converters (ADCs), in place of high sampling rate high resolution ADCs which may not be available in practice. Simulation results demonstrate that nonparametric TOA estimators provide more effective and robust performance than typical energy detection (ED) based estimators.
    No preview · Article · Feb 2015 · Journal of Systems Engineering and Electronics
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    ABSTRACT: Our research is focused on the development of an at-home health care biomonitoring mobile robot for the people in demand. Main task of the robot is to detect and track a designated subject while recognizing his/her activity for analysis and to provide warning in an emergency. In order to push forward the system towards its real application, in this study, we tested the robustness of the robot system with several major environment changes, control parameter changes, and subject variation. First, an improved color tracker was analyzed to find out the limitations and constraints of the robot visual tracking considering the suitable illumination values and tracking distance intervals. Then, regarding subject safety and continuous robot based subject tracking, various control parameters were tested on different layouts in a room. Finally, the main objective of the system is to find out walking activities for different patterns for further analysis. Therefore, we proposed a fast, simple, and person specific new activity recognition model by making full use of localization information, which is robust to partial occlusion. The proposed activity recognition algorithm was tested on different walking patterns with different subjects, and the results showed high recognition accuracy.1. IntroductionAt-home biomonitoring systems have become an important solution in the medical field as an assistive technology for the people who have difficulties leaving their houses, such as elderly people or motor-function impaired persons (MIPs) [1–8]. Benefits of these systems include more convenient and comfortable ways of healthcare for patients and reduction in the workload of the therapists [5–8].At-home healthcare applications cover a wide range of topics regarding physiological measurements or biomonitoring applications. Biomonitoring research in at-home health care emerged from the demand on improving the quality of life (QoL) of the people, such as to measure the vital signs, check their health over through the measurements, identify abnormalities from long-term at-home observation, and monitor rehabilitation assistance.In this research, our concern is mostly focused on the observation and analysis of motor function-related daily activities of the people in need such as the elderly and the motor-function impaired people. For this reason, tracking the subject and detection of daily activities are crucial tasks to be performed. The system should record data of continuous walking patterns for further analysis by the experts or computer-aided diagnosis systems. Therefore, in this study, we put our primary concern on tracking of subjects and detection of daily activities at-home with a mobile robot as an assistive technology to support the people with motor-function impairment.There are several approaches for daily observation that provide information about the activities that the subjects are performing [9–16]: (i) wearable sensors that include a wide range of different sensors such as accelerometers and (ii) smart house systems that implement solutions with multiple vision devices attached to certain fixed sites in a house. The main advantages of wearable systems are that they provide cheap and accurate solutions for activity recognition and analysis. The complexity of these systems, regarding the recognition algorithms and maintenance, is lower than other solutions such as smart houses with multiple-camera systems. However, the main disadvantage of wearable sensors is the attention required by the users. Subjects can be bothered by the fact that they have to wear many sensors and they have to be careful to avoid damaging the sensors while doing daily living things: sitting, eating, sleeping, and so forth. Quite often, subjects have to put on and off and charge the batteries of the sensors.On the other hand, smart houses do not have these disadvantages; daily activities can be tracked by systems that include multiple observation devices such as motion tracking systems, cmos/ccd cameras, and color and infrared cameras such as Kinect [8, 10, 11, 17, 18]. For instance, Tamura et al. [7] proposed an at-home biomonitoring system in which automated electrocardiogram (ECG) signals are measured and observed in some of the arranged places at home, such as bed, toilet, or bathroom, without using body surface electrodes. Even if they provide reliable observation capabilities to detect and analyze the daily activities performed by the subjects, they also have some disadvantages. Due to the number of observation devices, these systems are expensive and hard to set up and maintain. Moreover, despite the large number of sensory devices, it is still possible to have blind spots in indoor environments that can prevent the monitoring.As proposed in our previous works [5, 8, 19, 20], our main idea is to use assistive robotics to support elderly or motor-function impaired persons biomonitoring. Although a mobile system brings more complexity to handle daily observation tasks, a mobile robot solution includes several advantages: (i) it is a cheaper smart system than smart houses, (ii) it could make full use of the capability of sensors, since the sensors could be brought to a position and an angle optimal or suboptimal to observation, (iii) it avoids the multiple vision modules by using a mobile monitoring system, and (iv) it prevents the need of the subjects for wearing any sensors [5, 8, 19, 20] compared to wearable sensor applications. These advantages make the mobile robot a good candidate for assistive technologies. In addition, based on the Robocare project, Cesta et al. [21] made a preliminary experiment about the way that people evaluate the use of a robot at home for different purposes such as surveillance, service, or companion tasks [21, 22]. In most cases, the robot and subjects had some interactions considering the tasks for each scenario [21] such as accepting voice commands from subjects and serving. In these experiments, with 40 elderly subjects, activities that are usual to occur during the daily living were investigated [21]. After making a questionnaire to the experiment subjects, they gave a positive response [21] and supported the idea of having mobile robotics applications for at-home assistive tasks.1.1. Background Therefore, in our previous research [5, 8, 19, 20], we presented an at-home biomonitoring mobile robot project to improve the quality of life of motor-function impaired persons (MIPs). The robot observes the subject and recognizes the activity he is performing. It is also able to provide analysis of walking pattern if the lower limb joint trajectories were traceable [5, 8]. To achieve these tasks, there are several modules that have to be developed. Figure 1 presents the scheme of these modules.
    Full-text · Article · Dec 2014

Publication Stats

395 Citations
83.47 Total Impact Points

Institutions

  • 2006-2015
    • Shanghai Jiao Tong University
      • • Department of Automation
      • • School of Electronic, Information and Electrical Engineering
      Shanghai, Shanghai Shi, China
    • University of Science and Technology of China
      • Department of Electronic Engineering and Information Science
      Luchow, Anhui Sheng, China
  • 2010-2013
    • University of Electronic Science and Technology of China
      Hua-yang, Sichuan, China
  • 2011
    • Hefei University of Technology
      Luchow, Anhui Sheng, China
  • 2007-2009
    • Shanghai University
      • Department of Automation
      Shanghai, Shanghai Shi, China