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arXiv 2021年

作者： Kuang, Zhian Sun, Liting Gao, Huijun Tomizuka, Masayoshi Research Institute of Intelligent Control and Systems Harbin Institute of Technology Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Mechanical Control System Lab Mechanical Engineering Department University of California BerkeleyCA94720 United States

In this paper, a practical fractional-order variable-gain super-twisting algorithm (PFVSTA) is proposed to improve the tracking performance of wafer stages for semiconductor manufacturing. Based on the sliding mode control (SMC), the proposed PFVSTA enhances the tracking performance from three aspects: 1) alleviating the chattering phenomenon via super-twisting algorithm and a novel fractional-order sliding surface (FSS) design, 2) improving the dynamics of states on the sliding surface with fast response and small overshoots via the designed novel FSS and 3) compensating for disturbances via variable-gain control law. Based on practical conditions, this paper analyzes the stability of the controller and illustrates the theoretical principle to compensate for the uncertainties caused by accelerations. Moreover, numerical simulations prove the effectiveness of the proposed sliding surface and control scheme, and they are in agreement with the theoretical analysis. Finally, practice-based comparative experiments are conducted. The results show that the proposed PFVSTA can achieve much better tracking performance than the conventional methods from various perspectives. Copyright © 2021, The Authors. All rights reserved.

关键词： Sliding mode control

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Detection of privacy-sensitive situations for social robots in smart homes

Detection of privacy-sensitive situations for social robots ...

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IEEE International Conference on Automation Science and Engineering (CASE)

作者： Francisco Erivaldo Fernandes Guanci Yang Ha Manh Do Weihua Sheng Oklahoma State University System Stillwater OK US Key Laboratory of Advanced Manufacturing Technology of Ministry of Education Guizhou University Guiyang China School of Electrical and Computer Engineering Shenzhen Academy of Robotics Stillwater Shenzhen OK USA

ISBN: (纸本)9781509024100

The ubiquitous use of cameras in a home environment raises privacy concerns, which is one of the major barriers to the deployment of smart home systems for elderly and disabled care. Social robots are equipped with cameras that can witness embarrassing situations of their owners, such as nakedness during a morning bath. In this paper, our proposed solution is to let the robot detect such privacy-sensitive moments and then turn away to avoid observing the person. We proposed a method based on the Convolutional Neural Networks (CNN) to detect nakedness in a daily living scenario. In this method, two CNNs are used: one detects whether a person is present or not in the current scene, and the other detects privacy-sensitive situations. We implemented the method on the ASCC home service robot developed in our lab. The CNNs were trained with a database composed of more than 2900 pictures collected from the Internet and from our ASCC Smart Home. In our experiments, we considered three human poses: sitting, standing, and lying. If the robot detects a privacy-sensitive situation, it will turn around and verbally announce its intention, which ensures the person that he or she is not being watched. Our experiments validate the proposed privacy preserving method. We also conducted a user study and find that people prefer that the robot takes some actions to avoid directly watching them in privacy-sensitive situations.

关键词： Privacy Cameras Robot vision systems Service robots Smart homes Security

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Theoretical Modeling and Performance Analysis on the Linear Electromagnetic Actuator with High Nonlinear Dynamic Negative Stiffness

SSRN

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SSRN 2024年

作者： Wang, Chuchao Lu, Shizhou Liu, Xiaohan Mo, Wenyin Zhang, Bin Li, Kai Sun, Lining Mechanical Electrical & Information Engineering Shandong University Weihai264209 China School of Mechanical Engineering Dalian University of Technology Dalian116081 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China

Electromagnetic mechanisms are introduced to adjust the stiffness and improve the performance of mechanical systems, which have been widely researched. In this paper, the transient performance of a novel linear solenoid elastic actuator with higher nonlinear negative stiffness and speed by introducing the negative stiffness mechanism is analyzed and predicted. The actuator can achieve an initial theoretical stiffness of -20.96 N/m at 1 A current and a maximum stroke of 9 mm in 0.5 s. The performance indicators including peak time, overshoot, and steady-state displacement are obtained through electromagnetic-mechanical coupled modeling. The influence of system parameters including natural frequency, equivalent stiffness and damping coefficient on performance indicators is also studied. First, the approximate analytical model of the electromagnetic force is derived by constructing an innovative magnetic field distribution model. Second, the nonlinear vibration equation is solved theoretically to obtain the analytical results of the performance indicators and system parameters. Finally, the transient displacements and performance indicators obtained from the analytical model, the numerical model established in Simulink software and the simulation model obtained in Adams software are compared. The maximum errors of the peak time, overshoot and stable displacement through the analytical model and experiment are 2.56 ms, 9.37% and 0.32 mm, respectively. The theoretical and experimental results show the nonlinear effects of input currents on performance indicators and system parameters. The overshoot has a strong positive following feature on the damping coefficient, but the vibration frequency mainly depends on the equivalent stiffness of the system. This research provides a reference for the transient solution of nonlinear electromagnetic-dynamic coupling models and performance improvement of linear electromagnetic actuators. © 2024, The Authors. All rights reserved.

关键词： Stiffness

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Structure of the ball tensegrity robot

Structure of the ball tensegrity robot

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IEEE International Conference on robotics and Biomimetics

作者： Ani Luo R. E. Skelton Heping Liu Rongqiang Liu Hongwei Guo Longkun Wang College of Mechanical and Electrical Engineering Harbin Engineering University Harbin China Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA USA State Key Laboratory of Robotics and System (HIT) Harbin China

ISBN: (纸本)9781479973989

A new kind of ball tensegrity robot is researched. Firstly, build up mathematical model of ball tensegrity robot with its node matrix and member matrices. Based on the relationships between the nodes and members, the connectivity matrices are introduced. Then members can be expressed by connectivity matrix and node matrix. Under given external load, system equilibrium functions are set up, and we solve for the internal force density matrix of the tensegrity structure. Consideration yielding failure and buckling failure constraints, minimal mass of total structure is computed. The internal force density of the members is optimized to get the minimal mass. And minimal radii of members are derived. Simulation and physical structure test mode are made.

关键词： Force Bars Robots Silicon Mathematical model Shape Bismuth

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Model Design and Concept of Operations of Standard Interface for On-orbit Construction

Model Design and Concept of Operations of Standard Interface...

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IEEE International Conference on robotics and Automation (ICRA)

作者： Jingdong Zhao Zirui Wang Ziyi Liu Liangliang Zhao Qifan Duan Hong Liu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Chang Guang Satellite Technology Co. Ltd. Changchun China Beijing Honor Device Co. Ltd. Beijing China

ISBN: (数字)9798350384574

ISBN: (纸本)9798350384581

The construction of large-scale space facilities requires the use of on-orbit construction technology. However, several of its key components, such as standard interface design, compliant control methods, and path planning for multi-branch robots, still need improvement before practical application. This paper presents a comprehensive solution for on-orbit construction tasks, encompassing a novel standard interface, docking control method, and path planning method for space multi-branch robots. Firstly, a novel standard interface is introduced, which features multiple mating modes and a lightweight design. Additionally, a compliant docking method is provided to generate lower contact forces along the Z-direction. Furthermore, for four-armed space robots, a hierarchical planning method is proposed, which innovates in environment map construction and locomotion planning. Specifically, the closed-form Minkowski sum method is employed to solve the robot’s free space, and a concise locomotion method is elucidated based on transition support points. Finally, simulations and experiments are conducted.

关键词： Visualization Machine vision Prototypes Aerospace electronics Path planning Planning Task analysis

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A Novel Variable Stiffness Actuator Based on a Rocker-Linked Epicyclic Gear Train

SSRN

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SSRN 2022年

作者： Li, Zhisen Xu, Peng Huang, Hailin Ning, Yinghao Li, Bing State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China School of Mechanical Engineering and Automation Harbin Institute of Technology Shenzhen518055 China Zhengzhou Electromechanical Engineering Research Institute Zhengzhou450015 China

This paper presents a novel variable stiffness actuator based on a rocker-linked epicyclic gear train (REGT-VSA). The stiffness adjustment principle of the actuator is to change the lever ratio of force by converting the differential motion of the planetary gear train into the linear motion of the elastic element. The unique design of the rocker-linked epicyclic gear train ensures the compactness of structure and the accuracy of transmission. The simultaneous relocations of the pivot and torsion spring permit a wide-range stiffness adjustment. By introducing a linear guide and a cam follower, the internal friction is reduced, and the energy efficiency is improved. A prototype and its trajectory tracking controller are developed to evaluate the performance of REGT-VSA. An exponential function is used to train the neuron proportion coefficient of the conventional single-neuron adaptive PID (proportional-integral-derivative) controller to compensate for the hysteresis of elastic elements, thus creating the dynamic single-neuron adaptive PID controller. The stiffness identification and trajectory tracking experiments under different conditions prove the feasibility of the actuator and the proposed algorithm. © 2022, The Authors. All rights reserved.

关键词： Proportional control systems

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Joint Counting, Detection and Re-Identification for Multi-Object Tracking

arXiv

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arXiv 2022年

作者： Ren, Weihong Wu, Denglu Cao, Hui Chen, Xi'ai Han, Zhi Liu, Honghai The School of Mechanical Engineering and Automation State Key Lab of Robotics and Systems Harbin Institute of Technology Shenzhen518055 China The Shenzhen Duorou Intelligent System Co. Ltd. Shenzhen518055 China The School of Electrical Engineering Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Science Beijing110169 China

The recent trend in 2D multiple object tracking (MOT) is jointly solving detection and tracking, where object detection and appearance feature (or motion) are learned simultaneously. Despite competitive performance, in crowded scenes, joint detection and tracking usually fail to find accurate object associations due to missed or false detections. In this paper, we jointly model counting, detection and re-identification in an end-to-end framework, named CountingMOT, tailored for crowded scenes. By imposing mutual object-count constraints between detection and counting, the CountingMOT tries to find a balance between object detection and crowd density map estimation, which can help it to recover missed detections or reject false detections. Our approach is an attempt to bridge the gap of object detection, counting, and re-Identification. This is in contrast to prior MOT methods that either ignore the crowd density and thus are prone to failure in crowded scenes, or depend on local correlations to build a graphical relationship for matching targets. The proposed MOT tracker can perform online and real-time tracking, and achieves the state-of-the-art results on public benchmarks MOT16 (MOTA of 79.7%), MOT17 (MOTA of 81.3%) and MOT20 (MOTA of 78.9%). Source code is available at https://***/weihong9/CountingMOT. Copyright © 2022, The Authors. All rights reserved.

关键词： Object detection

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The consistent behavior of negative Poisson's ratio with interlayer interactions

arXiv

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arXiv 2022年

作者： Wang, Yancong Yu, Linfeng Zhang, Fa Chen, Qiang Zhan, Yuqi Zheng, Xiong Wang, Huimin Qin, Zhenzhen Qin, Guangzhao State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China Hunan Key Laboratory for Micro-Nano Energy Materials & Device School of Physics and Optoelectronics Xiangtan University Hunan Xiangtan411105 China School of Physics and Microelectronics Zhengzhou University Zhengzhou450001 China

Negative Poisson's ratio (NPR) is of great interest due to the novel applications in lots of fields. Films are the most commonly used form in practical applications, which involves multiple layers. However, the effect of interlayer interactions on the NPR is still unclear. In this study, based on first principles calculations, we systematically investigate the effect of interlayer interactions on the NPR by comparably studying single-layer graphene, few-layer graphene, h-BN, and graphene-BN heterostructure. It is found that they almost have the same geometry-strain response. Consequently, the NPR in bilayer graphene, triple-layer graphene, and graphene-BN heterostructure are consistent with that in single-layer graphene and h-BN. The fundamental mechanism lies in that the response to strain of the orbital coupling are consistent under the effect of interlayer interactions. The deep understanding of the NPR with the effect of interlayer interactions as achieved in this study is beneficial for the future design and development of micro-/nanoscale electromechanical devices with novel functions based on nanostructures. © 2022, CC BY-NC-SA.

关键词： Graphene

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An Acoustic Activated Nozzle for Microdroplet Generation and Dispensing

SSRN

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SSRN 2023年

作者： Yin, Qiu Li, Xiuyuan Ma, Zhichao Zhang, Wenming State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China Institute of Medical Robotics School of Biomedical Engineering Shanghai Jiao Tong University No.800 Dongchuan Road Shanghai200240 China

Droplet-based microfluidic has emerged as a versatile tool for widespread applications such as biochemical analysis and synthesis, for which the generation and manipulation of the microdroplets are the fundamental. Acoustic based droplet control has shown its advantages of good biocompatibility and widescale tunability. Here, we demonstrate an acoustic controlled nozzle that is integrated with both generation and directed dispensing of microdroplets. The system can generate monodisperse microdroplets with tunable sizes (50 μm – 641 μm) at a highest throughput of 2000 droplets per second. Besides, by tuning the acoustic frequency, the droplets can be steered to different directions after their formation, realizing on-demand dispensing of the microdroplets. The controlled microdroplet generation and dispensing are both attributed to the acoustic streaming effect induced by the nozzle vibration. Two basic mechanisms for the droplet control were studied: (1) the correlation between the droplet size and the acoustic actuation time, (2) the dependence of the droplet dispensing direction on the acoustic frequency. This work paves the way towards programmable control over acoustic generation and dispensing of microdroplets, which has great potential in the applications of bio-chemical analysis and synthesis. © 2023, The Authors. All rights reserved.

关键词： Biocompatibility

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Single-trial evoked potential estimation using an adaptive wavelet method

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ICIC Express Letters 2012年第9期6卷 2377-2382页

作者： Wang, Yongxuan Qiu, Tianshuang Liu, Rong Faculty of Electronic Information and Electrical Engineering Dalian University of Technology No. 2 Linggong Road Ganjingzi District Dalian 116024 China State Key Laboratory of Robotics and System Harbin Institute of Technology No. 92 West Dazhi Street Nangang District Harbin 150001 China

To estimate a signal from colored noises is a challenging problem because of the frequency overlap as well as the low signal-to-noise (SNR). In this paper, a novel adaptive wavelet method based on pre-whitening of colored EEG noises for single-trial evoked potential (EP) estimation is proposed. This method does not require prior information about the EPs. In particular, an adaptive weighted thresholding method is formulated using the least-mean-square error (LMSE) scheme to avoid manual selection of wavelet coefficients. For validation purposes, the proposed algorithm is assessed in its ability to extract brain EP corrupted by the colored EEG noises in which SNR values can be as low as -10 dB in real clinical environments. The experimental results show that this algorithm can successfully estimate dynamic changes in EPs, even under poor signal-to-noise ratio (SNR) conditions. © 2012 ICIC International.

关键词： Signal to noise ratio

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