Attitude Control for Astronaut Assisted Robot in the Space Station

Yangmin Li,Jinguo Liu,Qing Gao,Zhiwei Liu 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.4

Because of the limited working hours of astronauts in the space station, the in-cabin robot has high valuein the technological validation and scientific research. Based on this requirement, we proposed and designed an AstronautAssisted Robot(AAR) working in the space station. It can float in the space station cabin, fly autonomously,and hold a fixed position and/or posture. In addition, it also possesses environmental awareness capabilities andintelligence. Thus the AAR can assist astronauts to complete some special scientific experiments or technical tests. In this paper, the system architecture and experimental equipment of the AAR are designed firstly depending on thecharacteristics of space microgravity environment and the requirements of assisting astronauts missions. And then,the motion principles of the AAR are analyzed and the robot’s dynamic model is established by using the Newton- Euler algorithm. Since the attitude control of the robot is the basis for its free movement, the PID Neural Network(PIDNN) algorithm, which is a kind of intelligent control algorithm, is used to design the attitude controller ofthe AAR. Finally, the reasonability of the robot’s structural design and the availability of its attitude controllers areverified through the simulation experiments.

Distance Measurement of Zooming Image for a Mobile Robot

Hongwei Gao,Jinguo Liu,Yang Yu,Yangmin Li 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.4

Aiming at the application of zooming image distance measurement to mobile robot, the related key technologies are investigated in detail in this paper. Firstly, camera parameter calibration is conducted. The camera focus, optical center displacement between two foci, principal point and aberration coefficients are calculated accurately. Then, robust feature matching based on SIFT is realized by the geometrical constraint of a zooming image. Finally, the 3D reconstruction model of zooming image is established. The experimental results based on real sample images validate the practicability of the related algorithms.

On the role of surface diffusion in determining the shape or morphology of noble-metal nanocrystals

Xia, Xiaohu,Xie, Shuifen,Liu, Maochang,Peng, Hsin-Chieh,Lu, Ning,Wang, Jinguo,Kim, Moon J.,Xia, Younan National Academy of Sciences 2013 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.110 No.17

<P>Controlling the shape or morphology of metal nanocrystals is central to the realization of their many applications in catalysis, plasmonics, and electronics. In one of the approaches, the metal nanocrystals are grown from seeds of certain crystallinity through the addition of atomic species. In this case, manipulating the rates at which the atomic species are added onto different crystallographic planes of a seed has been actively explored to control the growth pattern of a seed and thereby the shape or morphology taken by the final product. Upon deposition, however, the adsorbed atoms (adatoms) may not stay at the same sites where the depositions occur. Instead, they can migrate to other sites on the seed owing to the involvement of surface diffusion, and this could lead to unexpected deviations from a desired growth pathway. Herein, we demonstrated that the growth pathway of a seed is indeed determined by the ratio between the rates for atom deposition and surface diffusion. Our result suggests that surface diffusion needs to be taken into account when controlling the shape or morphology of metal nanocrystals.</P>

Dual-layer Fuzzy Control Architecture for the CAS Rover Arm

Hongwei Gao,Yangmin Li,Jinguo Liu,Kun Hong,Yang Zhang 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5

Since the conventional impedance control method for a rover arm is not suitable for unconstructed environment with uncertainties, a fuzzy inference method which improves the impedance model dynamically is introduced to realize high-precision control. The fuzzy PD control algorithm which applies to the joint control of a rover arm is analyzed in this paper. With the two level control algorithms, a novel dual-layer fuzzy control framework is proposed, which can enhance the control performance significantly. In order to verify the validity and reliability of the designed algorithms, the robotic arm of the CAS rover is considered as an experimental platform. Kinematics and dynamics models of robotic arm are derived at first. Moreover, the fuzzy inference mechanism and implementation process of impedance model parameters are illustrated. Extensive simulations and experimental results show that the control accuracy and the force control of the system have been significantly improved with the proposed dual-layer fuzzy control architecture.

Mobile Robot Obstacle Avoidance Algorithms Based on Information Fusion of Vision and Sonar

Hongwei Gao,Qiuyang Wei,Yang Yu,Jinguo Liu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.8

In view of the problem of AS-R autonomous wheeled mobile robot obstacle avoidance, a rapid convergence of sonar and binocular stereovision sensor distance information in order to detect and avoid obstacle algorithm is proposed in this paper. The algorithm first uses binocular camera (CCD) to get three-dimensional image of the real environment, through the stereo matching and V-disparity method which is used to calculate disparity map, then obstacles is extracted by Hough lines detection algorithm, finally we will get information about obstacles and sonar return information with T-S fuzzy neural network fusion, then it will output walking controlled decisions. Experimental results proved that the algorithm is effective and practical.

Effect of Sulfur on Microstructures and Solidification Characteristics of a Nickel-Base Single Crystal Superalloy

Shaofeng Chen,Naicheng Sheng,Shigang Fan,Shijie Sun,Guichen Hou,Jinguo Li,Lirong Liu,Yizhou Zhou,Xiaofeng Sun 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

The effects of sulfur on the microstructures and solidification characteristics of a second-generation single crystal superalloywere clarified through optical microscope (OM), scanning electron microscope (SEM), differential scanning calorimetry(DSC) and electron probe microanalysis (EPMA). When sulfur was added to the alloy, the area fraction of theeutectic and microporosity decreased with the area fraction of MC carbides increasing. The γ / γ’ eutectic morphologychanged from mosaic + fan + coarse γ’ to mosaic + fan as the sulfur content increased, and very few γ / γ’ eutectic wasfound in the alloy with the highest sulfur content. Moreover, sulfur tended to segregate at the interdendritic regions andform Hf / Cr- rich sulfides, which were adjacent to the carbides or eutectic. This work not only uncovers some sulfideswrapped by eutectic or carbides, but also presents the solidification sequence of the interdendritic regions in high sulfurcontent alloy was discussed.

Design of ATA Interface Hard Disk Memory Card Used in Video Image Data

Li Jie,Sun Xiangyang,Li Mingjing,Yu Da,Liu Jinguo 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.9

In order to realize the current requirements of video image data memory card such as low power consumption, high storage density, high reading/writing speed, and enhancing the storage medium compatibility with improving the storage capacity and stability at the same time, we suggested a design of Video image data memory card using ATA interface hard-disk, and we use modularized design in this program, consists four parts: the image data buffer module, ATA logic module, ATA interface module, host communication module. Wherein the image data buffer module selects the CPLD plus external FIFO to complete makes the system only need to modify the CPLD program while working together with different external devices, which can improve the reliability and maintainability of the memory card that we designed. The functions of ATA logic module and ATA interface module are realized based on FPGA. The host communication module is completed by the AVR chips with TUSB6250 chip, ensuring the memory card has the advantages of low power consumption, internal short circuit protection and so on. In this paper, the proposed memory card scheme has the superiority such as lower cost, better compatibility, easy to expand, especially suitable for huge amounts of data in video store.

Accuracy modeling, analysis and radical error distribution of 3-RPR planar parallel mechanism

Jian Ding,Changlong Ye,Suyang Yu,Jianguang Li,Jinguo Liu,Guangbo Hao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11

Output accuracy performance is directly determined by geometric errors and working poses of a mechanism. Accuracy sensitivity as geometric error transmission coefficient, closely relates to pose configuration and geometric parameters. This research focuses on accuracy of a 3-RPR planar parallel mechanism: firstly, established 3 models in an analytic form, to describe relationship between output errors and geometric ones, then they are mutually verified statistically. Secondly, the anisotropy and periodic fluctuation of position errors, independently contributed by each category of geometric errors, are illustrated; and mirror symmetric trajectories and poses generating output errors with mirror symmetry, are also revealed by numerical simulation. Finally, the radical accuracy model in an analytic form, was established through variance and covariance analysis on output errors. We concluded that the radical error of the movable platform in central symmetric poses, follows Rayleigh distribution pattern. Through statistical comparison with Monte Carlo simulation, the radical error model was demonstrated, that provided a reference for accuracy design for other planar parallel mechanism.

Numerical study of rock-breaking performance of cutters in heterogeneous sand cobble ground

Jin Guo,Xiangwei Kong,Liu Cheng,Xueyi Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

Further research into tunneling performance in heterogeneous sand cobble ground demands an accurate numerical model of actual formation. In this paper, the ground model composed of spherical sand and ellipsoidal cobble was constructed to study the rockbreaking performance by using the discrete element method. The shape and physical parameters of sand and cobble were obtained on the basis of field test data. Then, the ground model was constructed to simulate the rock-breaking process of the cutterhead. The results show that the center cutter has a high flat wear percentage. With the decrease in cobble content (CC), the cracks between cutters are not connected effectively, thereby resulting in lower rock-breaking quantity. Finally, the influences of CC on the optimal parameters and crack propagation were analyzed. The results indicate that the rock-breaking performance in the ground with a low CC can be improved by increasing penetration and reducing cutter spacing.