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A Novel Estimating Method for Steering Efficiency of the Driver with Electromyography Signals

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Chinese Journal of Mechanical Engineering 2014年第3期27卷 460-467页

作者： liu yahui JI Xuewu HAYAMA Ryouhei MIZUNO Takahiro State Key Laboratory of Automotive Safety and Energy Tsinghua University Research and Development Center jtekt co.ltd.

The existing research of steering efficiency mainly focuses on the mechanism efficiency of steering system, aiming at designing and optimizing the mechanism of steering system. In the development of assist steering system especially the evaluation of its comfort, the steering efficiency of driver physiological output usually are not considered, because this physiological output is difficult to measure or to estimate, and the objective evaluation of steering comfort therefore cannot be conducted with movement efficiency perspective. In order to take a further step to the objective evaluation of steering comfort, an estimating method for the steering efficiency of the driver was developed based on the research of the relationship between the steering force and muscle activity. First, the steering forces in the steering wheel plane and the electromyography （EMG） signals of the primary muscles were measured. These primary muscles are the muscles in shoulder and upper ann which mainly produced the steering torque, and their functions in steering maneuver were identified previously. Next, based on the multiple regressions of the steering force and EMG signals, both the effective steering force and the total force capacity of driver in steering maneuver were calculated. Finally, the steering efficiency of driver was estimated by means of the estimated effective force and the total force capacity, which represented the information of driver physiological output of the primary muscles. This research develops a novel estimating method for driver steering efficiency of driver physiological output, including the estimation of both steering force and the force capacity of primary muscles with EMG signals, and will benefit to evaluate the steering comfort with an objective perspective.

关键词： electromyography muscle activity steering efficiency estimating

Inhomogeneous deformation of {111} grain in cold rolled tantalum

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Journal of Materials Science & Technology 2018年第11期34卷 2178-2182页

作者： yahui liu Shifeng liu Chao Deng Haiyang Fan Xiaoli Yuan Qing liu College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Electron Microscopy Center of Chongqing University Chongqing UniversityChongqing 400044China Department of Mechanical Engineering KU LeuvenLeuvenBelgium School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing 401331China

The microstructures of {111} grain were characterized in detailed and systematically investigated with the aid of electron backscatter diffraction(EBSD) and transmission electron microscope(TEM). The stored energy in different regions in the grain was evaluated by the band contrast values collected from EBSD. The results show that the distribution of energy is inhomogeneous through the grain. Especially,the regions containing the least and the largest energy were extracted from the EBSD data, and then quantitatively analyzed based on the misorientation and Schmid factor. Many peaks with large misorientation appeared in the region containing larger energy, and these peaks represent the existences of micro-bands and micro-shear bands in {111} grain. The results of Schmid factor suggest that the region containing larger energy is prone to deforming ahead of the region with less stored energy, implying the more serious subdivision of the microstructure of region with larger stored energy.

关键词： Tantalum Stored energy Misorientation Schmid factor

Beneficial clock-rolling cycles on the microstructure uniformity of {111} grains in tantalum sheets

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Progress in Natural Science:Materials International 2020年第1期30卷 124-127页

作者： Jialin Zhu Shifeng liu Shuai Yang yahui liu Adrien Chapuis College of Materials Science and Engineering Chongqing University

Controlling the texture of tantalum sheets is of critical importance to fabricate good sputtering *** the present study two tantalum sheets were produced by clock rolling to 70% thickness reduction in 1 or 2 *** results show that the stored energy and grain subdivision within the {111} grains {//normal direction(ND)} after 1 cycle are significantly higher than those after 2 cycles,leading to fast recrystallization kinetics and strong {111} recrystallized texture upon *** with Taylor model indicate that shear strain occurred on more slip systems in the 2-cycle sample,which could explain the formation of cell blocks in {111} grains.

关键词： Clock rolling cycle Texture Stored energy Taylor model Recrystallization kinetics

Objective Evaluation Method of Steering Comfort Based on Movement Quality Evaluation of Driver Steering Maneuver

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 1027-1037页

作者： YANG Yiyong liu yahui WANG Man JI Run JI Xuewu School of Engineering and Technology China University of Geosciences(Beijing) State Key Laboratory of Automotive Safety and Energy Tsinghua University National Research Center for Rehabilitation Technical Aids

The existing research of steering comfort mainly focuses on the subjective evaluation,aiming at designing and optimizing the steering *** the development of steering system,especially the evaluation of steering comfort,the objective evaluation methods considered the kinematic characteristics of driver steering maneuver are not proposed,which means that the objective evaluation of steering cannot be conducted with the evaluation of kinematic characteristics of driver in steering *** order to propose the objective evaluation methods of steering comfort,the evaluation of steering movement quality of driver is developed on the basis of the study of the kinematic characteristics of steering ***,the steering motion trajectories of the driver in both comfortable and certain extreme uncomfortable operation conditions are detected using the Vicon motion capture *** operation conditions are under the restrictions of the vertical height and horizontal distance between steering wheel center and the H-point of driver,and the steering resisting torque ***,the movement quality evaluation of driver steering maneuver is assessed using twelve kinds of evaluation indices based on the kinematic analyses of the steering motion trajectories to propose an objective evaluation ***,an integrated discomfort index of steering maneuver is proposed on the basis of the regression analysis of subjective evaluation rating and the movement quality evaluation indices,including the Jerk,Discomfort and Joint Torque *** test results show that the proposed integrated discomfort index gives a good fitting with the subjective evaluation of discomfort,which means it can be used to evaluate or predict the discomfort level of steering *** paper proposes an objective evaluation method of steering comfort based on the movement quality evaluation of driver steering maneuver.

关键词： steering maneuver movement quality evaluation driver discomfort

Generalized Internal Model Robust Control for Active Front Steering Intervention

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Chinese Journal of Mechanical Engineering 2015年第2期28卷 285-293页

作者： WU Jian ZHAO Youqun JI Xuewu liu yahui ZHANG Lipeng College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics School of Mechanical and Automotive Engineering Liaocheng University State Key Laboratory of Automotive Safety and Energy Tsinghua University

Because of the tire nonlinearity and vehicle＇s parameters＇uncertainties,robust control methods based on the worst cases,such as H_∞,μsynthesis,have been widely used in active front steering control,however,in order to guarantee the stability of active front steering system（AFS）controller,the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS *** this paper,a generalized internal model robust control（GIMC）that can overcome the contradiction between performance and stability is used in the AFS *** GIMC,the Youla parameterization is used in an improved *** GIMC controller includes two sections：a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters＇uncertainties and some external *** of double lane change（DLC）maneuver and that of braking on split-μroad are conducted to compare the performance and stability of the GIMC control,the nominal performance PID controller and the H_∞*** results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle＇s parameters variations,H_∞controller is conservative so that the performance is a little low,and only the GIMC controller overcomes the contradiction between performance and robustness,which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS ***,the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system,that is,can solve the instability of PID or LQP control methods and the low performance of the standard H_∞controller.

关键词： active front steering system generalized internal model robust control H_∞ optimization PID split-μ road

A misdiagnosed abdominal tumor due to rare cause

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Hepatobiliary Surgery and Nutrition 2020年第5期9卷 691-692页

作者： Baoxing Jia yahui liu Department of Hepatobiliary and Pancreatic Surgery the First Hospital of Jilin UniversityChangchunChina

Due to 3-day dull pain in the right upper abdomen,a 41-year-old woman was admitted to the *** had normal diet,bowel movement and no nausea or *** examination and laboratory tests were *** CT scan of the abdomen suggested a huge mass(10 cm diameter)at the pancreatic head that infringed the duodenum and hepatic colon flexure;intratumoral bleeding was noted(Panel A).Three year ago,she had undergone a local chest wall resection for dermatofibrosarcoma protuberans(DFSP).We hypothesized that the clinical diagnosis could be pancreatic or colon cancer.

关键词： colon admitted diagnosis

A modified structure internal model robust control method for the integration of active front steering and direct yaw moment control

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Science China(Technological Sciences) 2015年第1期58卷 75-85页

作者： WU Jian ZHAO YouQun JI XueWu liu yahui YIN ChengQiang Department of Automotive Engineering College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics School of Mechanical and Automotive Engineering Liaocheng University State Key Laboratory of Automotive Safety and Energy Tsinghua University

Taking into account the nonlinearity of vehicle dynamics and the variations of vehicle parameters,the integrated control strategy for active front steering(AFS)and direct yaw control(DYC)that can maintain the performance and robustness is a key issue to be ***,the H∞method is widely applied to the integrated control of chassis dynamics,but it always sacrifices the performance in order to enhance the *** modified structure internal model robust control(MSIMC)obtained by modifying internal model control(IMC)structure is proposed for the integrated control of AFS and DYC to surmount the conflict between performance and *** lane change(DLC)simulation is developed to compare the performance and the stability of the MSIMC strategy,the PID controller based on the reference vehicle model and the H∞*** results show that the PID controller may oscillate and go into instability in severe driving conditions because of large variations of tire parameters,the H∞controller sacrifices the performance in order to enhance the stability,and only the MSIMC controller can both ensure the robustness and the high performance of the integrated control of AFS and DYC.

关键词： modified structure internal model control robust control chassis integrated control double lane change

Point Cloud Classification Using Content-Based Transformer via Clustering in Feature Space

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 231-239页

作者： yahui liu Bin Tian Yisheng Lv Lingxi Li Fei-Yue Wang the State Key Laboratory for Management and Control of Complex Systems Institute of AutomationChinese Academy of SciencesBeijing 100190 the School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100190 IEEE the Transportation and Autonomous Systems Institute(TASI)and the Department of Electrical and Computer Engineering Purdue School of Engineering and TechnologyIndiana University-Purdue University Indianapolis(IUPUI)Indianapolis 46202 USA

Recently, there have been some attempts of Transformer in 3D point cloud classification. In order to reduce computations, most existing methods focus on local spatial attention,but ignore their content and fail to establish relationships between distant but relevant points. To overcome the limitation of local spatial attention, we propose a point content-based Transformer architecture, called PointConT for short. It exploits the locality of points in the feature space(content-based), which clusters the sampled points with similar features into the same class and computes the self-attention within each class, thus enabling an effective trade-off between capturing long-range dependencies and computational complexity. We further introduce an inception feature aggregator for point cloud classification, which uses parallel structures to aggregate high-frequency and low-frequency information in each branch separately. Extensive experiments show that our PointConT model achieves a remarkable performance on point cloud shape classification. Especially, our method exhibits 90.3% Top-1 accuracy on the hardest setting of ScanObjectN N. Source code of this paper is available at https://***/yahuiliu99/PointC onT.

关键词： Content-based Transformer deep learning feature aggregator local attention point cloud classification

Spontaneous regression of solid-pseudopapillary neoplasms with hepatic metastases

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Hepatobiliary Surgery and Nutrition 2022年第1期11卷 169-170页

作者： Xiaocheng Li yahui liu Department of Hepatobiliary and Pancreatic Surgery the First Hospital of Jilin UniversityChangchunChina

A 42-year-old female patient was presented to our hospital due to abdominal distension for 3 *** scan showed a huge mass(16 cm diameter)in the pancreatic tail and irregular low-density shadows(0.4-5.6 cm diameter)in the liver with left outer lobe atrophy(Panel A).These lesions have increased radioactive uptake in PET/CT(Panel B).The patient underwent distal pancreatectomy,splenectomy,left lateral hepatectomy and pathological examination confirmed the diagnosis of solid-pseudopapillary neoplasms(Panel C;staining method HE,magnification×20).

关键词： neoplasms diagnosis PET/CT