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Salient object detection via region contrast and graph regularization

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Science China(Information Sciences) 2016年第3期59卷 46-59页

作者： Xingming WU Mengnan DU weihai chen Jianhua WANG School of Automation Science and Electrical Engineering Beihang University

Detection of salient objects in an image is now gaining increasing research interest in computer vision community. In this study, a novel region-contrast based saliency detection solution involving three phases is proposed. First, a color-based super-pixels segmentation approach is used to decompose the image into regions. Second, three high-level saliency measures which could effectively characterize the salient regions are evaluated and integrated in an effective manner to produce the initial saliency map. Finally, we construct a pairwise graphical model to encourage that adjacent image regions with similar features take continuous saliency values, thus producing the more perceptually consistent saliency map. We extensively evaluate the proposed method on three public benchmark datasets, and show it can produce promising results when compared to 14state-of-the-art salient object detection approaches.

关键词： salient object detection region contrast region compactness global distinctness graph regular ization

Accuracy enhancement of the spherical actuator with a two-level geometric calibration method

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Chinese Journal of Aeronautics 2014年第2期27卷 328-337页

作者： Zhang Liang chen weihai Liu Jingmeng Wu Xingming chen I-Ming School of Automation Science and Electrical Engineering Beihang University School of Mechanical and Aerospace Engineering Nanyang Technological University

This paper presents a two-level geometric calibration method for the permanent magnet （PM） spherical actuator to improve its motion control accuracy. The proposed actuator is com- posed of a stator with circumferential coils and a rotor with multiple PM poles. Due to the assembly and fabrication errors, the real geometric parameters of the actuator will deviate from their design values. Hence, the identification of such errors is critical for the motion control tasks. A two-level geometric calibration approach is proposed to identify such errors. In the first level, the calibration model is formulated based on the differential form of the kinematic equation, which is to identify the geometric errors in the spherical joint. In the second level, the calibration model is formulated based on the differential form of torque formula, which is to calibrate the geometric parameters of the magnetization axes of PM poles and coils axes. To demonstrate the robustness and availability of the calibration algorithm, simulations are conducted. The results have shown that the proposed two-level calibration method can effectively compensate the geometric parameter errors and improve the positioning accuracy of the spherical actuator.

关键词： ACtuators Geometric calibration Parameter identification PositiOning accuracy Spherical actuator

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Application Analysis of Multiple Neurons Connected with Fast Inhibitory Synapses

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Journal of Bionic Engineering 2024年第4期21卷 1905-1918页

作者： Wen Duan weihai chen Jianhua Wang Zhongcai Pei Jingmeng Liu Jianer chen School of Automation Science and Electrical Engineering Beihang UniversityXueyuan RoadBeijing100191China Hangzhou Innovation Institute Beihang UniversityChuanghui StreetHangzhou310051ZhejiangChina School of Electrical Engineering and Automation Anhui UniversityAnhui230601ZhejiangChina Zhejiang Rehabilitation Medical Center Binsheng RoadHangzhou310052ZhejiangChina

Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural *** nonlinear oscillator models have been proposed to elucidate these neural behaviors and subsequently applied to the domain of robot ***,the oscillation patterns generated by these models are often unpredictable and need to be obtained through parameter *** study introduces a mathematical model that can be used to analyze multiple neurons connected through fast inhibitory *** characteristic of this oscillator is that its stationary point is stable,but the location of the stationary point changes with the system *** through reasonable topology and threshold parameter selection can the oscillation be *** study analyzed the conditions for stable oscillation in two-neuron networks and three-neuron networks,and obtained the basic rules of the phase relationship of the oscillator network established by this *** addition,this study also introduces synchronization mechanisms into the model to enable it to be synchronized with the sensing ***,this study used these theories to establish a robot single leg joint angle generation *** experimental results showed that the simulated robot could achieve synchronization with human motion,and had better control effects compared to traditional oscillators.

关键词： Oscillator Phase trajectory Synaptic threshold Synchronization Motion generation

An adaptive locomotion controller for a hexapod robot: CPG, kinematics and force feedback

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Science China(Information Sciences) 2014年第11期57卷 223-240页

作者： chen weihai REN GuanJiao WANG JianHua LIU Dong School of Automation Science and Electrical Engineering Beihang University

Insects can perform versatile locomotion behaviors such as multiple gaits, adapting to different terrains, fast escaping, etc. However, most of the existing bio-inspired legged robots do not possess such walking ability, especially when they walk on irregular terrains. To tackle this challenge, a central pattern generator(CPG)-based locomotion control methodology is proposed, integrated with a contact force feedback function. In this approach, multiple gaits are produced by the CPG module. After passing through a post-processing circuit and a delay-line, the control signal is fed into six trajectory generators to generate predefined feet trajectories for the six legs. Then, force feedback is employed to adjust these trajectories so as to adapt the robot to rough terrains. Finally the regulated trajectories are sent to inverse kinematics modules such that the position control instructions are generated to control the actuators. In both simulations and real robot experiments, we consistently show that the robot can perform sophisticated walking patterns. What is more, the robot can use the force feedback mechanism to deal with the irregularity in rough terrain. With this mechanism, the stability and adaptability of the robot are enhanced. In conclusion, the CPG-base control is an effective approach for legged robots and the force feedback approach is able to improve walking ability of the robots, especially when they walk on irregular terrains.

关键词： hexapod robot locomotion control central pattern generator(CPG) kinematics force feedback

Design,Simulation and Kinematic Validation of a Hip Prosthetic Mechanism with a Multimotor Function

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Journal of Bionic Engineering 2024年第3期21卷 1321-1333页

作者： Majun Song Zhongyi Li Jingjing Jiang weihai chen Sheng Guo Hao Zheng Lianzheng Niu Hangzhou Innovation Institute Beihang UniversityHangzhou310051China Hangzhou Huacheng Software Technology Co.Ltd. Hangzhou310051China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China

We previously developed a powered hip prosthetic mechanism with kinematic functions of hip flexion-extension and abduction-adduction,and its theoretical and simulation-based kinematics were *** internal-external hip rotation has a positive effect on the movements of human lower limbs according to medical research,we developed a novel hip prosthetic mechanism based on a previous hip prosthesis that possesses motion characteristics similar to those of a human bionic hip,and the motion characteristics of multiple Degrees-of-Freedom(DoFs)were analyzed after kinematic ***,a walking model of the human‒machine model was established,and the walking stability of an amputee,which reflects the rehabilitation effect,was explored while the hip prosthetic mechanism considered the internal-external rotation of the ***,a prototype and its verification platform were built,and kinematic validation of the hip prosthetic mechanism was carried *** results showed that the designed Parallel Mechanism(PM)possesses human-like motion characteristics similar to those of a human bionic hip and can be used as a hip ***,the existing motion characteristic of internal-external hip rotation can enhance the walking stability of an amputee via this hip prosthetic mechanism.

关键词： Hip prosthetic mechanism Parallel mechanism Walking stability Kinematic validation

A High Accuracy Signal Processing System for Six-dimensional Force Sensor

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A High Accuracy Signal Processing System for Six-dimensional...

Dimension reduction based SPM for image classification

第25届中国控制与决策会议

作者： Jianhua Wang Guoyu Lang weihai chen School of Automation Science and Electrical Engineering Beihang University

ISBN: (纸本)9781467355339

In order to deal with the small signal of six-dimensional force sensor, a high accuracy signal processing system is designed and implemented. This system mainly consists of instrumentation amplifier circuit, anti-aliasing filter, analog sampling module, master control unit, communication module, and user software based on LABWINDOWS platform. This paper analyzes structure of the sensor and equivalent circuit in detail, then amplifier circuit is designed according to the character of the signal. Meanwhile, anti-aliasing filter is designed to avoid the high frequency component of the original signal alias into the low frequency signal. The test results show that this system can reach to an accuracy of 0.06%, which is a fairly high accuracy. What’s more, the system can be transplanted to other small signal system easily.

关键词： Signal processing Instrumentation amplifier Anti-aliasing filter

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Dimension reduction based SPM for image classification

An indicator-guided photo-controlled drug delivery system based on mesoporous silica/gold nanocomposites

第25届中国控制与决策会议

作者： weihai chen Kai Ding Xingming Wu School of Automation Science and Electrical Engineering Beihang University

ISBN: (纸本)9781467355322

It is difficult to classify images with high accuracy when the dataset is relatively large. We try to improve classification precision in spatial pyramid matching （SPM） framework by dimension reduction. When clustering high dimension data, researchers encounter dimensional curse problem which would weaken statistical significance of the data. This problem degrades the performance of SPM and other related works based on clustering property of the high dimensional "SIFT" features. We propose a global dimensional reduction approach, reducing 128-d SIFT features to 32-d, and follow processes of locality-constrained linear coding to calculate feature histogram. Experimental results show that the proposed method leads to a better clustering property for the local descriptors, and increases image classification precision comparing to other state of the art algorithms on several image ***2007Bosch2007

关键词： data clustering image classification dimension reduction.

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Nano Research 2015年第6期8卷 1893-1905页

作者： Guofeng Luo weihai chen Huizhen Jia Yunxia Sun Han cheng Renxi Zhuo Xianzheng Zhang Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry Wuhan University Wuhan 430072 China

A mesoporous silica/gold （MSN/Au） nanocomposite was designed for photo- controlled drug delivery targeted specifically at tumor cells. The MSN/Au nanocomposite was composed of MSN-based drug carriers and gold nanoparticle （AuNP）-based indicators. While the MSN-based drug carrier was a mesoporous silica nanoparticle immobilized with photo-switchable azobenzene （Azo） moieties, the AuNP-based indicator was a fluorescence-quenched AuNP modified with a matrix metalloproteinase （MMP） substrate and poly（ethylene glycol）. The two kinds of nanoparticles were connected by an α,β cyclodextrin （α,β CD） dimer ＂bridge.＂ In vitro studies demonstrated that the nanocomposite specifically interacted with tumor sites overexpressing MMP-2, which enabled guidance of the subsequent UV light irradiation for releasing entrapped drugs. Through integration of the AuNP-based indicator and the MSN-based drug carrier, the MSN/Au nanocomposite could precisely localize the released drug to tumor sites, thereby significantly improving therapeutic efficacy.

关键词： MSN/Au nanocomposite photo-controlled MMP-2 sensitive drug delivery tumor therapy

Environmentally responsive dual-targeting nanotheranostics for overcoming cancer multidrug resistance

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Science Bulletin 2019年第10期64卷 705-714页

作者： Caixia Yang Xin Pang weihai chen Xiaoyong Wang Gan Lin chengchao Chu Xianzheng Zhang Xianming Deng Xiaoyuan chen Gang Liu State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics and Center for Molecular Imaging and Translational Medicine School of Public Health Xiamen University Xiamen 361102 China Key Laboratory of Biomedical Polymers of Ministry of Education & Department of Chemistry Wuhan University Wuhan 430072 China State Key Laboratory of Cellular Stress Biology Innovation Center for Cell Signaling Network School of Life Sciences Xiamen University Xiamen 361102 China Laboratory of Molecular Imaging and Nanomedicine National Institute of Biomedical Imaging and Bioengineering (NIBIB) National Institutes of Health (NIH) Bethesda MD 20892 USA

The development of multiple drug resistance(MDR) to chemotherapy and subsequent treatment failures are major obstacles in cancer therapy. An attractive option for combating MDR is inhibiting the expression of P-glycoprotein(P-gp) in tumor cells. Here, we report a novel chemosensitizing agent, XMD8-92,which can down-regulate P-gp. To enhance the specificity of MDR chemotherapy, a promising nanotheranostic micelle system based on poly(ethylene glycol)-blocked-poly(L-leucine)(PEG-b-Leu) was developed to simultaneously carry the anticancer drug doxorubicin, chemosensitizing agent XMD8-92, and superparamagnetic iron oxide nanoparticles(SPIOs). Featured with MDR environmentally responsive dual-targeting capability, controllable drug delivery, and efficient magnetic resonance(MR) imaging characteristics, the prepared nanotheranostics(DXS@NPs) showed outstanding in vitro cytotoxicity on MDR cells(SCG 7901/VCR) with only 53% of cells surviving compared to 90% of DOX-treated ***, efficient tumor inhibition and highly reduced systemic toxicity were exhibited by MDR tumor-bearing mice treated with DXS@NPs. Overall, the environmentally responsive dual-targeting nanotheranostics represent a promising approach for overcoming cancer MDR.

关键词： Cancer chemosensitization Multidrug resistance P-glycoprotein pH-responsive Magnetic resonance imaging

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