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arXiv 2020年

作者： Ajanic, E. Feroskhan, M. Mintchev, S. Noca, F. Floreano, D. Laboratory of Intelligent Systems École Polytechnique Fédérale de Lausanne Switzerland School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore Reconfigurable Robotics Laboratory École Polytechnique Fédérale de Lausanne Switzerland Haute école du Paysage D'ingénierie et D'architecture de Genève Switzerland

The operation of drones in cluttered environments and over extended areas demands adaptive flight capabilities to meet the opposing aerodynamic requirements of agile and fast cruise flight. High agility and maneuverability are required to aggressively navigate around obstacles and to perform instantaneous takeoffs or landings, while high energy efficiency is desired when covering large distances. In nature, these requirements are met by some birds by synergistic adaptation of wings and tail, such as the northern goshawk, which displays high agility and maneuverability when flying through forests and fast steady flight capabilities when ambushing prey in the open field. In this article, we experimentally study the effects of bio-inspired wing and tail morphing on flight performance by means of a novel morphing drone. We show that the combined morphing of wing and tail can improve agility, maneuverability, stability, flight velocity range, and energy efficiency of a winged drone. The drone's flight performance is validated in wind tunnel tests, shape optimization studies and outdoor flight tests. Copyright © 2020, The Authors. All rights reserved.

关键词： Wind tunnels

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Heuristics-based Adaptive Biased Random Walk Algorithm for Chemical Source Localization using AUVs

Heuristics-based Adaptive Biased Random Walk Algorithm for C...

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OCEANS

作者： Shubham Garg Antonio Pascoal Sanjeev Afzulpurkar Laboratory of Robotics and Engineering Systems (LARSyS) ISR/IST University of Lisbon Portugal Marine Instrumentation Division National Institute of Oceanography Goa India

We draw inspiration from the behavior of single-celled organisms to present a chemotaxis-inspired Adaptive Biased Random Walk (ABRW) guidance-control law for an Autonomous Underwater Vehicle (AUV). We build on previous results available in the literature to derive a random-walk based guidance-control law for an AUV to track-in and localize a potential chemical source in a turbulence-dominated environment. The ABRW-Strategy makes use of common plume-tracking and heuristic schemes for real-time path planning of the AUV. We further draw out a more comprehensive study of the guidance-strategy and extend the work for implementation in the Medusa class of vehicles that are developed in-house by Instituto Superior Tecnico (IST). The performance of the system is assessed via Hardware-in-the-loop (HIL) simulations to illustrate the viability of using random-walk for chemical source localization. The results obtained are encouraging for in-water tests with an autonomous vehicle of the Medusa class aiming at the validation of the proposed guidance-strategy in real-time experiments.

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Review of machine-vision-based plant detection technologies for robotic weeding

Review of machine-vision-based plant detection technologies ...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Li, Nan Zhang, Xiaoguang Zhang, Chunlong Ge, Luzhen He, Yong Wu, Xinyu Chinese Academy of Sciences Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Shenzhen518055 China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Shenzhen518055 China Shenzhen University Shenzhen518060 China China Agricultural University College of Engineering Beijing100083 China

ISBN: (纸本)9781728163215

Controlling weeds with reduced reliance on herbicides is one of the main challenges to move toward a more sustainable agriculture. Robotic weeding is a thought to be a viable way to reduce the environmental loading of agrochemicals while keeping the operation efficiency high. One of the key technologies for performing robotic weeding is automatic detection of crops and weeds in fields. This paper presents an overview on various methods for detecting plants based on machine vision, mainly concentrating on two main challenges: dealing with changing light and crop/weed discrimination. To overcome the first challenge, both physical and algorithmic methods have been proposed. Physical methods can result in a more cumbersome machine while algorithmic methods are less robust. For crop/weed discrimination, deep-learning-based methods have shown obvious advantages over traditional methods based on hand-crafted features. However, traditional methods still hold some merits that can be leveraged to deep-learning-based methods. With the fast development of hardware technologies, researchers should take full advantage of advanced hardware to ease the algorithm design. In the future, the identification of crops and weeds can be more accurate and fine-grained with the support of online databases and computing resources based on the advances in artificial intelligence and communication technologies. © 2019 IEEE.

关键词： Crops

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Bi-Modal Hemispherical Sensor: A Unifying Solution for Three Axis Force and Contact Angle Measurement

Bi-Modal Hemispherical Sensor: A Unifying Solution for Three...

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2019 IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Meng Yee Michael Chuah Lindsay Epstein Donghyun Kim Juan Romero Sangbae Kim Robotics and Autonomous Systems (RAS) department Institute for Infocomm Research (I2R) Singapore Biomimetic Robotics Laboratory at the Department of Mechanical Engineering Massachusetts Institute of Technology (MIT) Cambridge MA USA

In robotic tasks that require physical interactions such as manipulation and legged locomotion, it is important to simultaneously measure contact forces and contact angles. This paper presents a unified solution for simultaneously measuring three axis contact forces and contact angles for legged locomotion or manipulation. Unlike most tactile sensors, the presented design utilizes the stress field method by sampling pressures over multiple locations within an elastomer, enabling inherently robust operation against impact and abrasive interactions. The presented sensor is designed for point-feet quadrupedal robots and can be easily scaled down for other applications such as grasping. The sampled stress distribution is mapped to output forces f x , f y , and f z and two contact angles, θ and ψ on the hemispherical sensor surface via Gaussian process regression. The prototype sensor is able track normal and shear forces accurately, achieving a normalized root mean (RMS) squared error of only 1.00% - 1.36% for f z across multiple tests with up to 180N normal force, and a normalized RMS error of 1.71% - 4.67% and 1.82% - 6.68% for f x and f y , respectively, with up to 80N shear force. Additionally, the footpad is able to estimate the contact location coordinates θ and ψ with a normalized RMS error of 2.69% -7.51% over a range of 0-40° and 2.79% - 9.62% over a range of 0-30°, respectively. The footpad can estimate contact location over a maximum range of θ = ±45° and ψ = ±45°, and can withstand over 450N of normal force at location θ = ψ = 0° without reaching saturation. This prototype demonstrates the ability to simultaneously measure force in three axes and contact angles using Gaussian process regression, with the potential to explore other regression methods for embedded computing and miniaturization of the design for finger tip scale sensors.

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Movement Control and Attitude Adjustment of Climbing Robot on Flexible Surfaces

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IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS 2018年第3期65卷 2618-2628页

作者： Wu, Xinyu Liu, Jia Zhou, Yimin Lv, Qin Hu, Chaofang CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems and Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems and Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems and Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems and Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China School of Electrical and Information Engineering Tianjin University Tianjin China

In this paper, a series of control algorithms have been designed for the climbing cloth robot, "Clothbot" to climb vertically. The developed algorithm consists of three parts: a sliding mode control with integral action (SMC with integral action), a linear quadratic regulator, and dead reckoning for semi-autonomous navigation. First, the SMC with integral action is developed for high-precision position tracking and speed tracking of the permanent magnet direct current (PMDC) motor installed on the robot. The error between the expected velocity and the actual velocity of the PMDC motor is adopted to design the sliding surface. In order to compensate the fluctuation of the load torque due to the varied friction during climbing, an observer is formulated to estimate the load torque in real-time. Second, the LQR is employed for attitude adjustment by an active torque so as to prevent the robot from falling or being jammed during the movement. Third, due to the onboard-limited energy, the robot is just equippedwith semi-autonomous navigation named dead reckoning carrying on primary localization and primary path planning. Experiments are performed to verify the efficacy of the proposed control algorithms.

关键词： Climbing robot flexible surface linear quadratic regulator load observer sliding mode control with integral action

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Stairs reconstruction with 3D point cloud for gait generation of lower limb exoskeleton robot

Stairs reconstruction with 3D point cloud for gait generatio...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Feng, Yachun Xia, Linqing He, Yong Wang, Can Yan, Zefeng Wu, Xinyu Chinese Academy of Sciences Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology China CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology China Department of Mechanical and Automation Engineering Chinese University of Hong Kong Hong Kong

ISBN: (纸本)9781728163215

With the aging of the population, a considerable number of elderly persons suffer from walking disability. Lower limb exoskeleton robots have been proved to be effective in rehabilitation training and walking assistance. Though significant advancement has been made in the last decade, lacking the ability of adapting to complex terrain is one of the main challenges that restrict the wide application of exoskeleton robots. Thus we focus on the environmental perception and corresponding gait pattern generation of lower limb assistant exoskeleton. In this paper, we introduce a method to generate gait of exoskeleton walking on a stair, which applies the L-0 minimization-based acquisition and reconstruction of stairs information through 3D Point Cloud. The results of experiments show that our method can precisely measure the physical dimension information of stairs. © 2019 IEEE.

关键词： Stairs

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Development of a 4H-SiC Piezoresistive Pressure Sensor for High Temperature Applications

Development of a 4H-SiC Piezoresistive Pressure Sensor for H...

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IEEE International Conference on Nano/Micro Engineered and Molecular systems

作者： Xudong Fang Libo Zhao Chen Wu Yulong Zhao Xin Guo Zhuangde Jiang State Key Laboratory of Robotics and System (HIT) State Key Laboratory for Manufacturing Systems Engineering International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies Xi’an Jiaotong University 710049 Xi’an China State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong University 710049 Xi’an China

A piezoresistive pressure sensor based on 4H-SiC was developed for working over 500℃. The designed pressure range is 0-7MPa for special aviation applications. As demonstrated with experimental results, in this pressure range, the sensor shows excellent accuracy and repeatability from 30℃ to 500℃. Compared with previous studies, in MEMS processing of the sensor chip, a suitable alloy system was determined to form a stable high-temperature ohmic contact. Besides, the chip was packaged with mechanical structure and ceramic glue of similar thermal expansion coefficient to avoid thermal stress induced when increasing temperature. With the above measures taken, the sensor performance can be significantly improved. The design, fabrication, and package of this sensor provide support for high-temperature use. Additionally, this work can be a reference for future research in this field.

关键词： Pressure sensors Temperature sensors Piezoresistance Micromechanical devices Silicon carbide Conferences Thermal stresses

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Optimal Reaction Control for the Flexible Base Redundant Manipulator System*

Optimal Reaction Control for the Flexible Base Redundant Man...

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IEEE International Conference on robotics and Biomimetics

作者： Yaowen Zhang Yechao Liu Zongwu Xie Mehrdad Moallem State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China School of Mechatronic Systems Engineering Simon Fraser University Vancouver Canada

The null space of the Jacobian for the redundant manipulators can be utilized to reach dual control goals and optimal effects. For the flexible base redundant manipulator system, the reaction force from the motion of the manipulator should be carefully handled while the end effector is tracking a desired trajectory. Different optimal goals are discussed, including the minimization of base deflection force/torque and base energy dissipation path. Considering the base reaction dynamic, the reaction force/torque is treated as the input of the base and the deflection energy is treated as the output, an integrated optimal goal is built and solved based on the LQR control to get an optimal feedback for the closed-loop dynamics. We discuss the different optimal goals and implement trough the redefined acceleration. We test the different control laws on the three- link manipulators which mounted on a three-DoF flexible base. Simulation results demonstrate that optimal goal in LQR form can be advantageous in terms of flexible base manipulator.

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Vector Sensor Beam Steering for Underwater Acoustic Communications

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Proceedings of Meetings on Acoustics 2020年第1期42卷

作者： Fabricio de Abreu Bozzi Sergio M. Jesus 1Laboratory of Robotics and Engineering Systems (LARSys) University of Algarve Faro 8000-218 PORTUGAL fabriciobozzi@*** 2Laboratory of Robotics and Engineering Systems (LARSys) University of Algarve Faro 8005-139 PORTUGAL sjesus@ualg.pt

Acoustic Vector Sensors (VS) have been widely used for direction-of-arrival estimation in the past, while the employment of VS for underwater communications is a recent topic. Due to its compact size, VS may be used as a receiver in applications such as on board of Unmanned Underwater Vehicles (UUV), providing higher maneuverability and operational capabilities. Thus, in this study, the communication performance of a VS beam-steering technique is quantified. The performance analysis is made comparing the VS beam-steering with the VS time-reversal method in a shallow water simulation. The underwater channel is given by the seismo-acoustic propagation model, OASES. A Phase Shift Keying (PSK) modulation is adopted and the receiver includes a Decision Feedback Equalizer. An individual analysis of horizontal and vertical particle velocity is made to show the steering effects in the error performance. Moreover, as the steering angle is range-dependent, a comparison between methods is performed varying the range. The result indicates that the optimum steering angle, which brings less error, may not be related to the source direction. Furthermore, the proposed receiver shows the outperformance comparing to the time-reversal in both SNR and range, demonstrating the spatial filter advantage provided by this co-located sensor.

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Distributed algorithms that solve boolean equations with local and differential privacies

arXiv

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arXiv 2020年

作者： Qi, Hongsheng Li, Bo Jing, Rui-Juan Wang, Lei Proutiere, Alexandre Shi, Guodong Key Laboratory of Systems and Control Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China School of Mathematical Sciences University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China Faculty of Science Jiangsu University Zhenjiang212013 China Australian Center for Field Robotics School of Aerospace Mechanical and Mechatronic Engineering University of Sydney NSW2006 Australia Department of Automatic Control Kth Royal Institute of Technology Stockholm100-44 Sweden

In this paper, we propose distributed algorithms that solve a system of Boolean equations over a network, where each node in the network possesses only one Boolean equation from the system. The Boolean equation assigned at any particular node is a private equation known to this node only, and the nodes aim to compute the exact set of solutions to the system without exchanging their local equations. We show that each private Boolean equation can be locally lifted to a linear algebraic equation under a basis of Boolean vectors, leading to a network linear equation that is distributedly solvable using existing distributed linear equation algorithms as a subroutine. A number of exact or approximate solutions to the induced linear equation are then computed at each node from different initial values. The solutions to the original Boolean equations are eventually computed locally via a Boolean vector search algorithm. We prove that given solvable Boolean equations, when the initial values of the nodes for the distributed linear equation solving step are i.i.d selected according to a uniform distribution in a high-dimensional cube, our algorithms return the exact solution set of the Boolean equations at each node with high probability. Furthermore, we present an algorithm for distributed verification of the satisfiability of Boolean equations, and prove its correctness. Finally, we show that by utilizing linear equation solvers with differential privacy to replace the in-network computing routines, the overall distributed Boolean equation algorithms can be made differentially private. Under the standard Laplace mechanism, we prove an explicit level of noises that can be injected in the linear equation steps for ensuring a prescribed level of differential privacy. Copyright © 2020, The Authors. All rights reserved.

关键词： Linear equations

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