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IEEE International Conference on robotics and Automation (ICRA)

作者： Sheng Xiang Haibo Gao Zhen Liu Clément Gosselin State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China Département de génie mécanique Université Laval Québec City Canada

ISBN: (数字)9781728173955

ISBN: (纸本)9781728173962

This paper presents a trajectory optimization formulation for planning dynamic trajectories of a six-degree-of-freedom (six-DOF) cable-suspended parallel robot (CSPR) that extend beyond the static workspace. The optimization is guided by low-dimensional dynamic models to overcome the local minima and accelerate the exploration of the narrow feasible state space. The dynamic similarity between the six-DOF CSPR and the three-DOF point-mass CSPR is discussed with the analyses of their feasible force polyhedra. Finally, the transition trajectories of a three-DOF CSPR are used as the initial guess of the translational part of the six-DOF motion. With the proposed approach, highly dynamic motions for a six-DOF CSPR are efficiently generated with multiple oscillations. The feasibility is demonstrated by point-to-point and periodic trajectories in the physics simulation.

关键词： Dynamics Planning Robots Trajectory optimization Chebyshev approximation

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Experiments on the relationship between the structural parameters of contraposition transducers and the acoustic levitation transportation trajectory

Experiments on the relationship between the structural param...

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2019 International Congress on Ultrasonics, ICU 2019

作者： Dong, Huijuan Sui, Mingyang Mao, Chuncheng Mu, Guanyu Zhao, Jie School of Mechatronics Engineering Harbin Institute of Technology Hei Longjiang Harbin150001 China State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Harbin150001 China

ISBN: (纸本)9781665407090

Standing wave acoustic levitation transportation technique has been widely used in many research areas. In this work, two Langevin-type piezoelectric transducers' central lines are mounted at a certain angle which is named a contraposition transducer array. The levitator developed in this work is constructed using the array and a reflector. Accordingly, a standing wave acoustic field is formed to levitate and transport particles by optimizing the angle between central lines of the two transducers, the distance between the two transducers' output and their reflectors, the exciting phase differential on the two transducers. In this standing wave acoustic field, the trapped objects can be levitated and transported by modulating the exciting phase difference of the two transducers. In this work, the locations of the levitated particles are acquired by a high speed video camera and are clarified using the Hough Circle algorithm. The experiments carried out by the authors have demonstrated the effects of the levitator's structure parameters (including the angle between central lines of the two transducers, the distance between the two transducers' output and the reflector) on the transportation trajectory. © 2020 Acoustical Society of America.

关键词： Video cameras

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Dual-durometer combination of vacuum cup for aerial grasping

Dual-durometer combination of vacuum cup for aerial grasping

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IEEE International Conference on Real-time Computing and robotics (RCAR)

作者： Sensen Liu Wei Dong Zhao Ma Dongxiao Sun Xinjun Sheng State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University and Robotics Institute Shanghai China School of Mechanical Engineering Shanghai Jiao Tong University Shanghai China

ISBN: (数字)9781728172934

ISBN: (纸本)9781728172941

In the application of a conventional vacuum cup, a large compression force is required to eliminate the gap between the end of the cup and the object surface. However, the large interaction force will be a challenge for micro flying robots to grasp the object in the air using the suction cup as a gripper. To address the problem, a dual-durometer combined vacuum cup for aerial grasping is proposed. The combined cup is composed of one outer hard cup and one inner soft cup. The soft cup is longer than the hard one so the initial contact phase is implemented by the soft cup. The required compression force to engage the soft cup is dramatically decreased. The hard cup will be guided and pressed by the adhesion force induced by the soft one. Therefore, a larger adhesion force can be provided by the outer hard cup. The comparative experiments of static error-tolerance and aerial grasping have been conducted. The results demonstrate that the required contact pressure is significantly reduced and the object can be grasped robustly.

关键词： Force Grasping Adhesives Payloads Lips Bellows Adsorption

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Design of a series elastic actuator with double-layer parallel spring for lower limb exoskeletons

Design of a series elastic actuator with double-layer parall...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Chen, Chaofeng Wu, Dongmei Dong, Wei Du, Zhijiang He, Long Huang, Linxiang Wang, Jiaqi Shi, Yongjun Xu, Guoqiang Si, Fang Xiao, Tiantian Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin Heilongjiang Province China China South Industries Group Corporation Weapon Equipment Research Institute Beijing China

ISBN: (纸本)9781728163215

This paper presents a novel Series Elastic Actuator (SEA) with double-layer parallel spring for lower limb exoskeletons (LLE). The SEA can improve the human-robot interaction comfort and have the ability to absorb shock and vibration. In order to make the assembly process simple and convenient, the series elastic unit adopt split structure, which includes an inner ring structure, an outer ring structure and rectangular springs as elastic element. At the same time, in order to meet the requirements of the stiffness and dimensions of the SEA, a double-layer parallel spring arrangement is adopted. The stiffness of SEA is 312Nm/rad, which is obtained by the stiffness calibration experiment. In the experiments, the SEA is used in the knee joint of LLE and an impedance controller is designed to achieve knee joint tracking motion. Finally, the experiments results show the position tracking performance of the LLE, which illustrates the effectiveness of the SEA. © 2019 IEEE.

关键词： Human robot interaction

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Design of dielectric-elastomer actuated XY stages with millimeter range and submicrometer resolution

Design of dielectric-elastomer actuated XY stages with milli...

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International Conference on Manipulation, Automation and robotics at Small Scales (MARSS)

作者： Ningyuan Ding Jiang Zou Guoying Gu Robotics Institute School of Mechanical Engineering Shanghai Jiao Tong University Shanghai China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai China

ISBN: (数字)9781728193496

ISBN: (纸本)9781728193502

In this paper, we present the development and performance evaluation of dielectric-elastomer actuated XY (DEA-XY) stages with a millimeter range and submicrometer resolution. The design of the DEA-XY stage is based on a circular dielectric-elastomer actuator with two vertically distributed electrodes that can generate a two degree-of-freedom motion. To optimize their performances, various DEAXY stages with different dimensions and pre-stretches are firstly fabricated. Then, both static and dynamic performances of the DEA-XY stages are investigated by experiments, which demonstrate that: i) the workspace of the DEA-XY stage can reach 2.5 mm × 2.5 mm; ii) the cross-coupling effect is less than 6.5%; iii) the dynamic responses of the DEA-XY stage show both viscoelastic creep and hysteresis nonlinearities. To demonstrate the resolution of the DEA-XY stage, we implement a feedback controller to remove the creep effect. By tracking step trajectories, the results show that the DEA-XY stage can achieve the positioning resolution of 100 nm. This work demonstrates the potential application of the DEA-XY stage in the field of microscale manipulators.

关键词： Electrodes Creep Actuators Micromanipulators High-voltage techniques Hysteresis Fabrication

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Using rgb image as visual input for mapless robot navigation

arXiv

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arXiv 2019年

作者： Ma, Liulong Liu, Yanjie Chen, Jiao State Key Laboratory of Robotics and System Harbin Institute of Technology China

Robot navigation in mapless environment is one of the essential problems and challenges in mobile robots. Deep reinforcement learning is a promising technique to tackle the task of mapless navigation. Since reinforcement learning requires a lot of explorations, it is usually necessary to train the agent in the simulator and then migrate to the real environment. The big reality gap makes RGB image, the most common visual format, rarely used. In this paper we present a learning-based mapless motion planner taking RGB image as visual input. In the end-to-end navigation network many of the parameters are used to extract visual features. The proposed motion palnner decoupled visual features extracted module from the reinforcement learning network to improve the sample efficiency. Variational Autoencoder (VAE) is used to encode the image, and the obtained latent vector is input as low-dimensional visual features into the network together with the target and motion information. We built and released a set of simulation environments for algorithm comparison. In the test environment, the proposed method was compared with the end-to-end network, which proved its effectiveness and efficiency. The source code is available: Https://***/marooncn/navbot. Copyright © 2019, The Authors. All rights reserved.

关键词： Deep learning

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Diffusive nonreciprocity and thermal diode

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Physical Review B 2021年第1期103卷 014307-014307页

作者： Ying Li Jiaxin Li Minghong Qi Cheng-Wei Qiu Hongsheng Chen Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Hangzhou 310027 China International Joint Innovation Center ZJU-UIUC Institute The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin 150001 China

Wave propagation and diffusion in linear materials preserve local reciprocity in terms of a symmetric Green's function. For wave propagations, the relation between the fields entering and leaving a system is more relevant than the detailed information about the fields inside it. In such cases, the global reciprocity of the scattering off a system through several ports is more important, which is defined as the symmetric transmission between the scattering channels. When a two-port system supports nonreciprocal (electromagnetic, acoustic) wave propagation, it is a (optical, phonon) diode directly following the definition. However, to date no concrete definition or discussion has been made on the global reciprocity of diffusive processes through a multiple-port system. It thus remains unclear what are the differences and relations between the three concepts, namely, local nonreciprocity, global nonreciprocity, and diode effect in diffusion. Here, we provide theoretical analysis on the frequency-domain Green's function and define the global reciprocity of heat diffusion through a two-port system, which has a different setup from that of a thermal diode. We further prove the equivalence between a heat transfer system with broken steady-state global reciprocity and a thermal diode, assuming no temperature-dependent heat generation. The validities of some typical mechanisms in breaking the diffusive reciprocity and making a thermal diode have been discussed. Our results set a general background for future studies on symmetric and asymmetric diffusive processes.

关键词： Diffusion Heat transfer Metamaterials Diodes Green's function methods

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Using spanwise flexibility of caudal fin to improve swimming performance for small fishlike robots

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Journal of Hydrodynamics 2018年第5期30卷 859-871页

作者： Dan Xia Wei-shan Chen Jun-kao Liu Xiang Luo School of Mechanical Engineering Southeast UniversityNanjing 211189China State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

This paper examines the beneficial effects of the spanwise flexibility of the caudal fin for the improvement of the swimming performance for small fishlike robots. A virtual swimmer is adopted for controlled numerical experiments by varying the spanwise flexible trajectories and the spanwise flexible size of the caudal fin while keeping the body kinematics fixed. 3-D Navier-Stokes equations are used to compute the viscous flow over the robot. Elliptical, parabolic and hyperbola trajectories are chosen to describe the spanwise flexible profile of the caudal fin. According to the sign（positive or negative） of the phase difference of the swinging motion, the spanwise flexibility can be divided into the fin surface of ＂bow＂ and the fin surface of ＂scoop＂. It is observed that for both the fin surface of ＂bow＂ and the fin surface of ＂scoop＂, the spanwise elliptical trajectory has the optimal swimming velocity, thrust, lateral force, and efficiency. With comparisons, using the flexible caudal fin with the fin surface of ＂bow＂, the lateral force and the power consumption can be reduced effectively and the swimming stability can be increased while reducing little the swimming velocity and thrust. Meanwhile, using the flexible caudal fin with the fin surface of ＂scoop＂ can greatly improve the swimming velocity, thrust, and efficiency while increasing part of the lateral force and the power consumption. Three-dimensional flow structures clearly indicate the evolution process around the swimming robot. It is suggested that the fish, the dolphin, and other aquatic animals may benefit their hydrodynamic performance by the spanwise flexibility of the caudal fin.

关键词： Spanwise flexibility caudal fin fishlike robot swimming performance flow structures

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A Novel Method of Combining Computer Vision, Eye-Tracking, EMG, and IMU to Control Dexterous Prosthetic Hand

A Novel Method of Combining Computer Vision, Eye-Tracking, E...

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IEEE International Conference on robotics and Biomimetics

作者： Chunyuan Shi Le Qi Dapeng Yang Jingdong Zhao Hong Liu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

Due to poor robustness, instability, and the heavy burden of use, the traditional myoelectric control method is still powerless in the face of the control of the dexterous prosthetic hand. To solve this problem, a new method (CVEEI), that combines computer vision, eye tracking, electromyogram (EMG) and IMU was proposed in this paper. Firstly, through gazing (eye-tracking) in front of the screen, the grasping pattern of the objects can be fed back to the prosthetic hand controller; Then, the prosthetic hand can be controlled to transport the object to the position expected, on collaboration of both EMG and IMU. In this process, the grasping pattern of all objects can be recognized by computer vision in real-time. Importantly, through comparing the traditional EMG control method (co-contraction to switch) in the transport experiment of the objects, the superiority of this new method in operating the dexterous prosthetic hand was further verified (fast > 1s/single object) in this paper.

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Design of A Close-range Radiotherapy Particle Implantation Device*

Design of A Close-range Radiotherapy Particle Implantation D...

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IEEE International Conference on robotics and Biomimetics

作者： Guang Ban Changle Li Xuehe Zhang Gangfeng Liu Yubin Liu Jie Zhao Leifeng Zhang Yilun Fan State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

The validity of brachytherapy has been proved in clinical tumor treatment, and robotic surgery system has been used in recent years to ensure surgical consistency. In our work, a new automatic radioactive particle implantation device with two degrees of freedom was proposed to apply in the brachytherapy robotic surgery system as an end effector. Furthermore, physical assembling and simple function verifying experiments were accomplished. This device can help simplify the operating steps during surgery, and improve the stability of the surgical system, and enhances the surgical efficiency.

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