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Incremental Non-Gaussian Inference for SLAM Using Normalizing Flows

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arXiv 2021年

作者： Huang, Qiangqiang Pu, Can Khosoussi, Kasra Rosen, David M. Fourie, Dehann How, Jonathan P. Leonard, John J. MIT Computer Science and Artificial Intelligence Laboratory CambridgeMA02139 United States MIT Department of Nuclear Science and Engineering CambridgeMA02139 United States Robotics and Autonomous Systems Group DATA61 CSIRO BrisbaneQLD4069 Australia Northeastern University Department of Electrical and Computer Engineering BostonMA02115 United States NavAbility BostonMA02110 United States MIT Department of Aeronautical and Astronautical Engineering CambridgeMA02139 United States

This paper presents normalizing flows for incremental smoothing and mapping (NF-iSAM), a novel algorithm for inferring the full posterior distribution in SLAM problems with nonlinear measurement models and non-Gaussian factors. NF-iSAM exploits the expressive power of neural networks, and trains normalizing flows to model and sample the full posterior. By leveraging the Bayes tree, NF-iSAM enables efficient incremental updates similar to iSAM2, albeit in the more challenging non-Gaussian setting. We demonstrate the advantages of NF-iSAM over state-of-the-art point and distribution estimation algorithms using range-only SLAM problems with data association ambiguity. NF-iSAM presents superior accuracy in describing the posterior beliefs of continuous variables (e.g., position) and discrete variables (e.g., data association). Copyright © 2021, The Authors. All rights reserved.

关键词： Gaussian noise (electronic)

Super-resolution multicolor fluorescence microscopy enabled by an apochromatic super-oscillatory lens with extended depth-of-focus

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arXiv 2022年

作者： Li, Wenli He, Pei Fan, Yulong Du, Yangtao Gao, Bo Chu, Zhiqin An, Chengxu Lei, Dangyuan Yuan, Weizheng Yu, Yiting Research & Development Institute of Northwestern Polytechnical University in Shenzhen College of Mechanical Engineering Ningbo Institute of Northwestern Polytechnical University Northwestern Polytechnical University Xi'An710072 China Northwestern Polytechnical University Xi'An710072 China Shaanxi Province Key Laboratory of Micro and Nano Electro-Mechanical Systems Northwestern Polytechnical University Xi'An710072 China Department of Materials Science and Engineering City University of Hong Kong 999077 Hong Kong The Institute of Ai and Robotics Fudan University Shanghai200433 China Key Laboratory of Spectral Imaging Technology of Chinese Academy of Sciences Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xian710119 China Department of Electrical and Electronic Engineering Joint Appointment with School of Biomedical Sciences The University of Hong Kong 999077 Hong Kong

Multicolor super-resolution imaging remains an intractable challenge for both far-field and near-field based super-resolution techniques. Planar super-oscillatory lens (SOL), a far-field subwavelength-focusing diffractive lens device, holds great potential for achieving sub-diffraction-limit imaging at multiple wavelengths. However, conventional SOL devices suffer from a numerical aperture (NA) related intrinsic tradeoff among the depth of focus (DoF), chromatic dispersion and focus spot size, being an essential characteristics of common diffractive optical elements. Typically, the limited DoF and significant chromatism associated with high NA can lead to unfavorable degradation of image quality although increasing NA imporves the resolution. Here, we apply a multi-objective genetic algorithm (GA) optimization approach to design an apochromatic binary-phase SOL that generates axially jointed multifoci concurrently having prolonged DoF, customized working distance (WD) and suppressed side-lobes yet minimized main-lobe size, optimizing the aforementioned NA-dependent tradeoff. Experimental implementation of this GA-optimized SOL demonstrates simultaneous focusing of blue, green and red light beams into an optical needle of ∼0.5λ in diameter and >10λ in length (DoF) at 428 μm WD, resulting in an ultimate resolution better than λ/3 in the lateral dimension. By integrating this apochromatic SOL device with a commercial fluorescence microscope, we employ the optical needle to perform, for the first time, three-dimensional super-resolution multicolor fluorescence imaging of the "unseen" fine structure of neurons at one go. The present study provides not only a practical route to far-field multicolor super-resolution imaging but also a viable approach for constructing imaging systems avoiding complex sample positioning and unfavorable photobleaching. Copyright © 2022, The Authors. All rights reserved.

关键词： Needles

Attitude observers aided by implicit measurements of the Earth angular velocity

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Attitude observers aided by implicit measurements of the Ear...

IEEE Conference on Decision and Control

作者： Joel Reis Carlos Silvestre Pedro Batista Paulo Oliveira Faculty of Science and Technology University of Macau Taipa Macao China Instituto Superior Técnico Universidade de Lisboa Portugal Institute for Systems and Robotics LARSyS Instituto Superior Técnico Universidade de Lisboa Lisboa Portugal LAETA — Associated Laboratory for Energy Transports and Aeronautics IDMEC — Institute of Mechanical Engineering Instituto Superior Técnico Universidade deLisboa Lisboa Portugal

ISBN: (数字)9781728174471

ISBN: (纸本)9781728174488

In this tutorial, a new class of attitude estimation solutions is presented to determine the orientation of a robotic platform resorting only to a set of triaxial gyroscopes and an additional measurement of a constant inertial vector. This approach poses a significant advantage in terms of setup design and reduced mission costs since only one inertial measurement is required, in contrast with existing solutions that require at least two of these. Pertinent examples of viable applications include navigation of submarines or large ships, assisting autonomous robots in precise maneuvers, inertial platform stabilization, etc. The novelty of the solutions proposed herein exploit the well-known inertial information about the Earth's angular velocity by using high-grade gyroscopes that are sensitive to the planet's spin. Experimental results are presented to demonstrate the good performance achieved by the algorithms.

关键词： Observers Extraterrestrial measurements Earth Robot sensing systems Angular velocity Tutorials Gyroscopes

Variable Stiffness Control with Strict Frequency Domain Constraints for Physical Human-Robot Interaction

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arXiv 2020年

作者： Zou, Wulin Duan, Pu Chen, Yawen Yu, Ningbo Shi, Ling Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Hong Kong Hong Kong Xeno Dynamics Co. Ltd Shenzhen China Institute of Robotics and Automatic Information Systems Tianjin Key Laboratory of Intelligent Robotics Nankai University Tianjin China

Variable impedance control is advantageous for physical human-robot interaction to improve safety, adaptability and many other aspects. This paper presents a gain-scheduled variable stiffness control approach under strict frequency-domain constraints. Firstly, to reduce conservativeness, we characterize and constrain the impedance rendering, actuator saturation, disturbance/noise rejection and passivity requirements into their specific frequency bands. This relaxation makes sense because of the restricted frequency properties of the interactive robots. Secondly, a gain-scheduled method is taken to regulate the controller gains with respect to the desired stiffness. Thirdly, the scheduling function is parameterized via a nonsmooth optimization method. Finally, the proposed approach is validated by simulations, experiments and comparisons with a gain-fixed passivity-based PID method. Copyright © 2020, The Authors. All rights reserved.

关键词： Frequency domain analysis

One to many: Adaptive instrument segmentation via meta learning and dynamic online adaptation in robotic surgical video

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arXiv 2021年

作者： Zhao, Zixu Jin, Yueming Lu, Bo Ng, Chi-Fai Dou, Qi Liu, Yun-Hui Heng, Pheng-Ann The Department of Computer Science and Engineering The Chinese University of Hong Kong Hong Kong The T Stone Robotics Institute The Department of Mechanical and Automation Engineering The Chinese University of Hong Kong Hong Kong Guangdong-Hong Kong-Macao Joint Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences China The Department of Surgery The Chinese University of Hong Kong Hong Kong

Surgical instrument segmentation in robot-assisted surgery (RAS) - especially that using learning-based models - relies on the assumption that training and testing videos are sampled from the same domain. However, it is impractical and expensive to collect and annotate sufficient data from every new domain. To greatly increase the label efficiency, we explore a new problem, i.e., adaptive instrument segmentation, which is to effectively adapt one source model to new robotic surgical videos from multiple target domains, only given the annotated instruments in the first frame. We propose MDAL, a meta-learning based dynamic online adaptive learning scheme with a two-stage framework to fast adapt the model parameters on the first frame and partial subsequent frames while predicting the results. MDAL learns the general knowledge of instruments and the fast adaptation ability through the video-specific meta-learning paradigm. The added gradient gate excludes the noisy supervision from pseudo masks for dynamic online adaptation on target videos. We demonstrate empirically that MDAL outperforms other state-of-the-art methods on two datasets (including a real-world RAS dataset). The promising performance on ex-vivo scenes also benefits the downstream tasks such as robot-assisted suturing and camera control. Copyright © 2021, The Authors. All rights reserved.

关键词： Surgical equipment

Graphical Characterizations for Structural Controllability of Drifted Bilinear systems

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Graphical Characterizations for Structural Controllability o...

IEEE Conference on Decision and Control

作者： Xing Wang Bo Li Jr-Shin Li Ian R. Petersen Guodong Shi Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing School of Mathematical Sciences University of Chinese Academy of Sciences Beijing China Washington University St. Louis MO USA Research School of Engineering Australian National University Canberra ACT Australia Australian Center for Field Robotics School of Aerospace Mechanical and Mechatronic Engineering The University of Sydney NSW Australia

ISBN: (纸本)9781665436601

In this paper, we study graphical conditions for structural controllability and accessibility of drifted bilinear systems over Lie groups. We consider a bilinear control system with drift and controlled terms that evolves over the special orthogonal group and the special unitary group. Zero patterns are prescribed for the drift and controlled dynamics with respect to a set of base elements in the corresponding Lie algebra. The drift dynamics must respect a rigid zero- pattern in the sense that the drift takes values as a linear combination of base elements with strictly non-zero coefficients; the controlled dynamics are allowed to follow a free zero pattern with potentially zero coefficients in the configuration of the controlled term by linear combination of the controlled base elements. First of all, for such bilinear systems over the special orthogonal group, the zero patterns are shown to be associated with two undirected graphs whose connectivity and connected components ensure structural controllability. Next, for bilinear systems over the special unitary group, we introduce two edge- colored graphs associated with the drift and controlled zero patterns, and prove structural controllability conditions related to connectivity and the number of edges of a particular color.

关键词： Algebra Conferences Color Controllability Nonlinear systems Computational complexity

Position control of XY precision planar motion table based on input shaping filter

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Position control of XY precision planar motion table based o...

International Conference on Electronics, Communications and Information Technology (CECIT)

作者： HuaLiang Zhang Xu Lu DanPing Jia BingJie Zhao Tao Zhang Yang Liu HongYu Yan Key Laboratory of Networked Control Systems Chinese Academy of Sciences Shenyang China Shenyang Institute of Automation Chinese Academy of Sciences Shenyang China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences Shenyang China School of Artificial Intelligence Shenyang University of Technology Shenyang China School of Information Science and Engineering Shenyang University of Technology Shenyang China

ISBN: (纸本)9781665437585

In order to solve the vibration problem of mining equipment, a Simulink simulation model of current loop, speed loop and position loop of permanent magnet synchronous motor was established to track the input position signal of the motor system.[1] At the same time, the input shaper is introduced into the motor three loop control model to study the vibration suppression effect of the input shaper.[2] The essence of the input shaper is to filter the input signal. Usually, the parameters of the input shaper need to be accurately identified and the detailed parameters of the system need to be identified. However, the problem that the identification accuracy of the system is not enough often makes the parameters of the shaper uncertain. In view of the problem that the system identification is not accurate, a method of adjusting and setting input shaper parameters is designed, which is not very dependent on the system. The results show that the optimal parameters of the shaper can be selected by the method. Compared with the parameters of the shaper selected according to the identification model, the vibration suppression effect is better.

关键词： Vibrations Analytical models Tracking loops Software packages Magnetic separation Transfer functions Position control

Design of a Highly Reliable SRAM Cell with Advanced Self-Recoverability from Soft Errors

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Design of a Highly Reliable SRAM Cell with Advanced Self-Rec...

International Test Conference in Asia (ITC-Asia)

作者： Zhengda Dou Albin Yan Jun Zhou Yuanjie Hu Yan Chen Tianming Ni Jie Cui Patrick Girard Xiaoqing Wen School of Computer Science and Technology Anhui University/Anhui Engineering Laboratory of IoT Security Technologies Hefei China College of Electrical Engineering Anhui Polytechnic University Wuhu China Laboratory of Informatics Robotics and Microelectronics of Montpellier University of Montpellier/CNRS Montpellier France Graduate School of Computer Science and Systems Engineering Kyushu Institute of Technology Fukuoka Japan

ISBN: (数字)9781728189444

ISBN: (纸本)9781728189451

In this paper, a highly reliable SRAM cell, namely SESRS cell, is proposed. Since the cell has a special feedback mechanism among its internal nodes and has more access transistors compared to a standard SRAM cell, the SESRS cell provides the following advantages: (1) it can self-recover from single node upsets (SNUs) and double-node upsets (DNUs); (2) it can reduce power consumption by 49.78% and silicon area by 7.92%, compared with the only existing SRAM cell which can self-recover from all possible DNUs. Simulation results validate the robustness of the proposed SESRS cell. Moreover, compared with the state-of-the-art hardened SRAM cells, the proposed SESRS cell can reduce read access time by 61.93% on average.

关键词： SRAM cells Transistors Integrated circuit reliability Logic gates Standards Robustness Reliability engineering

Position Sensorless Control of Permanent Magnet Synchronous Motor Based on Adaptive Sliding Mode Observer

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Position Sensorless Control of Permanent Magnet Synchronous ...

Chinese Automation Congress (CAC)

作者： Tao Zhang Yingjie Xiong Bolun Wang Hongyu Yan Xiyou Chen School of Electrical Engineering Dalian University of Technology Dalian China Shenyang Institute of Automation Chinese Academy of Sciences Shenyang China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences Shenyang China Key Laboratory of Networked Control Systems Chinese Academy of Sciences Shenyang China College Of Information Science and Engineering Northeastern University Shenyang China School of Artificial Intelligence Shenyang University of Technology Shenyang China

ISBN: (纸本)9781665426480

Permanent magnet synchronous motors(PMSM) are popular in AC motor applications due to their small size, high efficiency. They have appeared widely in various areas of life. Due to the high-frequency chattering problem caused by sliding mode observer sensorless control of PMSM, an SMO with piecewise control function is designed in this paper. At the same time, based on the back EMF output of the SMO, the gain of the SMO is adapted to reduce the system bucket vibration problem caused by the conventional SMO. Finally, a simulation experiment was carried out in MATLAB/SIMULINK and compared with the conventional SMO. The results show that the improved SMO has achieved a better control effect.

关键词： Vibrations Adaptation models AC motors Force Sensorless control Observers Permanent magnet motors