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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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Understanding the friction behavior and surface characteristic in multiple ball-end milling passes of soft-brittle KH2PO4 optics

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Tribology International 2025年 211卷

作者： Lei, Hongqin Zhao, Qiang Cheng, Jian Zhao, Linjie Chen, Mingjun Liu, Qi Yang, Dinghuai Chen, Guang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150001 China School of Mechatronics Engineering Harbin Institute of Technology Harbin150001 China Zhengzhou Research Institute Harbin Institute of Technology Zhengzhou450000 China Department of Mechanical Engineering University of Bath BathBA2 7AY United Kingdom

The utilization of a ball-end cutter to fabricate multi-layer microstructures is the preferred technique for eliminating surface defects in soft-brittle KH2PO4 (KDP) optics. However, the previous milling pass would inevitably affect the tool-workpiece friction behavior and surface characteristics in the next milling process, which poses a great challenge to obtaining a defect-free microstructure surface. In this study, the effect of the multiple ball-end milling (MBEM) passes on material removal mode is explored according to tensile stress, residual stress and cutting force, which is verified from the perspectives of surface characteristics and roughness. The spindle speed, feed rate and milling depth of each-pass machining process are 50,000 r/min, 3 mm/s and 2 μm. The evaluation models of tool-workpiece friction behavior during the MBEM passes are developed, and the influence of soft-brittle materials on tool wear is analyzed. The results show that with when the number of milling passes (i) rises, the normalized plowing friction coefficient, tool-chip contact length and area increase, indicating that the tool-workpiece friction becomes severe. Meanwhile, with the rise in the i, the stress concentration area and surface roughness increase, which is attributed to the intensified tool-workpiece friction leading to an increase in cutting forces, thereby elevating the tensile stress exerted on the brittle KDP materials. When the i reaches 4, the brittle-plastic transition behavior occurs and edge chippings appear on the down-cut side. Furthermore, after the MBEM passes (the length of the milling path reaches 330 mm), there is no crack at the grain boundary, single grain spalling or even tool fracture on the CBN tool surface. Nevertheless, the low hardness of the KDP materials (2.18 GPa), coupled with the thermal softening effect, results in many chips adhering to the tool surface. The chemical composition of the built-up edge (BUE) consists of K, P and O. In particular

关键词： Surface defects

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Design of A Close-range Radiotherapy Particle Implantation Device*

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

引用

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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Real-time Dynamic Grasping Force Optimization of Multi-fingered Dextrous Hand *

Real-time Dynamic Grasping Force Optimization of Multi-finge...

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IEEE International Conference on robotics and Biomimetics

作者： Ziqi Liu Li Jiang Bin Yang State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

A technique for real-time dynamic grasping force optimization is presented in this article. The force optimization is divided into online and offline two parts. The improved linear constrained gradient flow algorithm reduces the dimension of the description matrix based on the traditional gradient flow, and the non-negative linear combination method is introduced to optimize the initial force of the algorithm. Relatively optimal initial grasping force and dimensionality reduction gradient flow algorithm improve the calculating efficiency online. The corresponding illustrative examples are made to verify that the proposed method to obtain both optimal grasping force and faster convergence rate in the dynamic grasp process is feasible.

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Closed-Form Analytical Model of Binding Force for Wheeled Mobile Robots with Skid-Steering Mechanism Running on Sandy Terrains

Closed-Form Analytical Model of Binding Force for Wheeled Mo...

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IEEE International Conference on Cyber Technology in Automation, Control, and Intelligent systems

作者： Junlong Guo Xin Meng Liang Ding Haibo Gao Huang Bo Weihua Li Zongquan Deng State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

ISBN: (数字)9781728107707

ISBN: (纸本)9781728107714

Wheeled mobile robot (WMR) with skid-steering mechanism is popular due to its simplicity and robust performance. Dynamic models of skid-steering systems are very important to their control, and binding force is one essential component of the dynamic models. Integrating the bulldozing resistance force determined using Hegedus's theory along the wheel side face to estimate the binding force is a common way. However, due to the complexity of Hegedus's equations, it is hard to use the binding force model online. To solve this problem, the equivalent wheel sinkage is utilized to compute the bulldozing resistance force, which can then be used to develop a closed-form analytical expression of binding force. The analytical model is used to compute the binding force based on the experimental results obtained using a six-wheeled mobile robot running on a sandy terrain UM-LSS1 and the measured terrain mechanical parameters. Under the specific experimental conditions described in this paper, the binding force exerted on the wheel side face can be neglected for the cases with light vehicle and low forward velocity.

关键词： Conferences Robots Automation Control systems Intelligent systems Wheels Force

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A Vector Control Method of PMSM Using Single Phase Current Sensor

A Vector Control Method of PMSM Using Single Phase Current S...

引用

IEEE International Conference on robotics and Biomimetics

作者： Chuangqiang Guo Chunya Wu Fenglei Ni Hong Liu State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin China

This paper presents a new method of realizing vector control for the surface mounted permanent magnet synchronous machine (PMSM) using single phase current sensor. A simplified estimating method of phase current, which only requires the information from single phase current sensor and motor position sensor, has been proposed in this paper. Compared with the classical approaches, based on the reference current in synchronous rotor frame, the proposed method can get better accuracy, especially when there is a sudden change of the reference current. Furthermore, the method not relays on the model and parameters of PMSM and the control performance of current close-loop and also not sensitive to working conditions. The extensively experimental results under different work conditions, based on MATLAB/SIMULINK, have validated the feasibility and robustness of the proposed vector control method.

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An Adaptable Robotic system for Assembling Irregular Earphone Parts on Factory Automation

An Adaptable Robotic System for Assembling Irregular Earphon...

引用

IEEE International Conference on robotics and Biomimetics

作者： Guiwei Zhang Changle Li Xuehe Zhang Gangfeng Liu Yubin Liu Jie Zhao Shuo Xu. State Key Laboratory of Robotics and System Harbin Institue of Technology Harbin China

The assembly of earphone parts in electro acoustic factory automation is a challenging problem for industrial robots. The main difficulties come from the fact that conventional industrial robots perform poorly on rapid-updated earphone parts, which are characterized by small size, variety and irregular shapes. What's worse, the robot cannot adapt to the earphone parts with different poses effectively. In order to tackle above problems, an adaptable robotic system guided by the 3D laser triangulation sensor and six-axis F/T sensor is built in this paper. In addition, to reduce position errors caused by the 3D sensor accidently, an assembly strategy which is implemented by the admittance controller learned from human teaching, is proposed for assembling earphone parts. Specifically, AdaBoost-based GPR method is applied to derive the admittance gain, so that the controller perform effectively. A series of comparative experiments prove that the established system could demonstrate superior performance on the earphone parts with small size, variety and irregular shapes. Furthermore, it is also validated that the assembly strategy could be executed effectively on the earphone parts with different poses.

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