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| 1 | Three-line structured light vision system for non-cooperative satellites in proximity operations显示文摘Adapter ring is a commonly used component in non-cooperative satellites,which has high strength and is suitable to be recognized and grasped by the space manipulator.During proximity operations,this circle feature may be occluded by the robot arm or limited field of view.Moreover,the captured images may be underexposed when there is not enough illumination.To address these problems,this paper presents a structured light vision system with three line lasers and a monocular camera.The lasers project lines onto the surface of the satellite,and six break points are formed along both sides of the adapter ring.A closed-form solution for real-time pose estimation is given using these break points.Then,a virtual structured light platform is constructed to simulate synthetic images of the target satellite.Compared with the predefined camera parameters and relative positions,the proposed method is demonstrated to be more effective,especially at a close distance.Besides,a physical space verification system is set up to prove the effectiveness and robustness of our method under different light conditions.Experimental results indicate that it is a practical and effective method for the pose measurement of on-orbit tasks. | Yang LIU Zongwu XIE Hong LIU | 2020 | Chinese Journal of Aeronautics2020，33，5： | 1 |
| 2 | Comparative analyses of the textures of the timbers of Fnkien cypress, China fir and the artificial forest of Masson's pine 显示文摘 | Xiao Xiangxi Yang Zongwu Ye Zhonghua | 2000 | News Report of Forestry Science and Technology2000，，2： | 1 |
| 3 | Rare tree provenance Fukiencypress显示文摘 | Zheng Renhua Hou Boxing | 1988 | News Report of Forestry Science and Technology1988，，7： | 1 |
| 4 | Comparative analyses of the textures of the timbers of Fukiencypress,China fir and the artificial forest of Masson's pine显示文摘 | Yang Zongwu Ye Zhonghua | 2000 | News Report of Forestry Science and Technology2000，，2： | 1 |
| 5 | Preliminary report of the seedling studies for the migrated cultivation of Fukiencypress显示文摘 | Huang Libin Yang Zongwu | 1999 | Jiangsu Forestry Science and Technology1999，27，3： | 1 |
| 6 | Trajectory planning and base attitude restoration of dual-arm free-floating space robot by enhanced bidirectional approach显示文摘When free-floating space robots perform space tasks,the satellite base attitude is disturbed by the dynamic coupling.The disturbance of the base orientation may affect the communication between the space robot and the control center on earth.In this paper,the enhanced bidirectional approach is proposed to plan the manipulator trajectory and eliminate the final base attitude variation.A novel acceleration level state equation for the nonholonomic problem is proposed,and a new intermediate variable-based Lyapunov function is derived and solved for smooth joint trajectory and restorable base trajectories.In the method,the state equation is first proposed for dual-arm robots with and without end constraints,and the system stability is analyzed to obtain the system input.The input modification further increases the system stability and simplifies the calculation complexity.Simulations are carried out in the end,and the proposed method is validated in minimizing final base attitude change and trajectory smoothness.Moreover,the minute internal force during the coordinated operation and the considerable computing efficiency increases the feasibility of the method during space tasks. | Zongwu XIE Xiaoyu ZHAO Zainan JIANG Haitao YANG Chongyang LI | 2022 | Frontiers of Mechanical Engineering2022，17，1： | 0 |
| 7 | A policy iteration method for improving robot assembly trajectory efficiency显示文摘Bolt assembly by robots is a vital and difficult task for replacing astronauts in extravehicular activities(EVA),but the trajectory efficiency still needs to be improved during the wrench insertion into hex hole of bolt.In this paper,a policy iteration method based on reinforcement learning(RL)is proposed,by which the problem of trajectory efficiency improvement is constructed as an issue of RL-based objective optimization.Firstly,the projection relation between raw data and state-action space is established,and then a policy iteration initialization method is designed based on the projection to provide the initialization policy for iteration.Policy iteration based on the protective policy is applied to continuously evaluating and optimizing the action-value function of all state-action pairs till the convergence is obtained.To verify the feasibility and effectiveness of the proposed method,a noncontact demonstration experiment with human supervision is performed.Experimental results show that the initialization policy and the generated policy can be obtained by the policy iteration method in a limited number of demonstrations.A comparison between the experiments with two different assembly tolerances shows that the convergent generated policy possesses higher trajectory efficiency than the conservative one.In addition,this method can ensure safety during the training process and improve utilization efficiency of demonstration data. | Qi ZHANG Zongwu XIE Baoshi CAO Yang LIU | 2023 | Chinese Journal of Aeronautics2023，36，3： | 0 |
| 8 | A noncontact robot demonstration method with human supervision显示文摘The widely used kinesthetic demonstration method of dragging robotic manipulators cannot obtain reliable information for autonomous robot manipulation because an additional external force rather than pure contact force will be reflected on the force sensor in end-constrained manipulation tasks. Therefore, a noncontact robot demonstration method with human supervision is proposed to avoid external influence. A human demonstrator sends motion commands by mouse and observes force data reflected in a monitor to protect the robotic manipulator. Simultaneously, the human demonstrator supervises the positionorientation relationship between the end-effector and the manipulated object. The wrench insertion task is adopted to illustrate the advantage of the proposed method. A contact model is established according to demonstration data acquired from the proposed demonstration method, and an orientation adjustment strategy is verified. The strategy verification experiment illustrates not only the effectiveness of the simplified contact model and corresponding strategy but also the advantage of the proposed demonstration method. | ZHANG Qi XIE ZongWu LIU Yang | 2021 | Science China(Technological Sciences)2021，64，11： | 0 |
| 9 | Gecko-Like Dry Adhesive Surfaces and Their Applications: A Review显示文摘Gecko has the ability to climb flexibly on various natural surfaces because of its fine layered adhesion system of foot,which has motivated researchers to carry out a lot of researches on it.Significant progresses have been made in the gecko-like dry adhesive surfaces in the past 2 decades,such as the mechanical measurement of adhesive characteristics,the theoretical modeling of adhesive mechanism and the production of synthetic dry adhesive surfaces.Relevant application researches have been carried out as well.This paper focuses on the investigations made in recent years on the gecko-like dry adhesive surfaces,so as to lay the foundation for further research breakthroughs.First,the adhesion system of gecko’s foot and its excellent adhesive characteristics are reviewed,and the adhesive models describing the gecko adhesion are summarily reviewed according to the diff erent contact modes.Then,some gecko-like dry adhesive surfaces with outstanding adhesive characteristics are presented.Next,some application researches based on the gecko-like dry adhesive surfaces are introduced.Finally,the full text is summarized and the problems to be solved on the gecko-like dry adhesive surfaces are prospected. | Wei Wang Yang Liu Zongwu Xie | 2021 | Journal of Bionic Engineering2021，18，5： | 0 |
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