Because of their elastic links and joints,high-speed parallel robots for pick-and-place operations inevitably suffer from residual vibrations that significantly degrade their positioning accuracy.An effective approach...Because of their elastic links and joints,high-speed parallel robots for pick-and-place operations inevitably suffer from residual vibrations that significantly degrade their positioning accuracy.An effective approach based on the input shaping technique is presented in this paper for suppressing the residual vibration in these parallel robots.After addressing the design principle of an input shaper for a parallel robot with flexible actuated joints,a robust optimal input shaper is developed by considering the configuration-dependent flexible modes and minimizing the maximum percentage of residual vibration at the end-effector.The input shaper allows a good overall performance to be achieved throughout the entire workspace.Experimental results on a 4-DOF SCARA-type parallel robot show that the residual vibration of the end-effector is dramatically reduced and the dynamic positioning accuracy of the robot significantly improved.展开更多
This paper deals with the conceptual design, kinematic analysis and workspace identification of a novel four degrees-of-freedom （DOFs） high-speed spatial parallel robot for pick-and-place operations. The proposed sp...This paper deals with the conceptual design, kinematic analysis and workspace identification of a novel four degrees-of-freedom （DOFs） high-speed spatial parallel robot for pick-and-place operations. The proposed spatial parallel robot consists of a base, four arms and a 11/2 mobile platform. The mobile platform is a major innova- tion that avoids output singularity and offers the advantages of both single and double platforms. To investigate the characteristics of the robot＇s DOFs, a line graph method based on Grassmann line geometry is adopted in mobility analysis. In addition, the inverse kinematics is derived, and the constraint conditions to identify the correct solution are also provided. On the basis of the proposed concept, the workspace of the robot is identified using a set of presupposed parameters by taking input and output transmission index as the performance evaluation criteria.展开更多
Micro-light emitting diode(micro-LED)is an emerging display technology with excellent performance of high contrast,low power consumption,long lifetime,and fast response time compared with the current display(e.g.,liqu...Micro-light emitting diode(micro-LED)is an emerging display technology with excellent performance of high contrast,low power consumption,long lifetime,and fast response time compared with the current display(e.g.,liquid crystal and organic LED(OLED)).With technological advantages,micro-LED holds promise to be widely applied in augmented reality(AR),flexible screens,etc.and is thus regarded as the next generation of display technology.In the process flow of micro-LED,the step known as mass transfer that requires transferring millions of micro-LEDs from a growth substrate to a display plane,is one of the key challenges limiting the commercialization of micro-LED from laboratory.Worldwide academic and industrial efforts have been devoted to developing mass transfer strategies with purposes of improving yield and reducing cost.Herein we review three main categories of mass transfer technologies for micro-LED display(pick-and-place,fluid self-assembly and laser-enabled advanced placement)and the coupled detection and repair technologies after transfer.Discussions and comparisons have been provided about the underlying general principle,history,and representative parties,advantages,and disadvantages(yield/efficiency/cost)of these technologies.We further envision the application prospect of these transfer technologies and the promise of the future display of micro-LED.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51721003)State Key Laboratory of Robotics and System(HIT)(Grant No.SKLRS–2018–KF-09)。
文摘Because of their elastic links and joints,high-speed parallel robots for pick-and-place operations inevitably suffer from residual vibrations that significantly degrade their positioning accuracy.An effective approach based on the input shaping technique is presented in this paper for suppressing the residual vibration in these parallel robots.After addressing the design principle of an input shaper for a parallel robot with flexible actuated joints,a robust optimal input shaper is developed by considering the configuration-dependent flexible modes and minimizing the maximum percentage of residual vibration at the end-effector.The input shaper allows a good overall performance to be achieved throughout the entire workspace.Experimental results on a 4-DOF SCARA-type parallel robot show that the residual vibration of the end-effector is dramatically reduced and the dynamic positioning accuracy of the robot significantly improved.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 51425501）, and by the Beijing Municipal Science ＆ Technology Commission （Grant No. ZI7110000 0817007）. The second author wishes to acknowledge the support provided by the Alexander yon Humboldt （AvH） Foundation.
文摘This paper deals with the conceptual design, kinematic analysis and workspace identification of a novel four degrees-of-freedom （DOFs） high-speed spatial parallel robot for pick-and-place operations. The proposed spatial parallel robot consists of a base, four arms and a 11/2 mobile platform. The mobile platform is a major innova- tion that avoids output singularity and offers the advantages of both single and double platforms. To investigate the characteristics of the robot＇s DOFs, a line graph method based on Grassmann line geometry is adopted in mobility analysis. In addition, the inverse kinematics is derived, and the constraint conditions to identify the correct solution are also provided. On the basis of the proposed concept, the workspace of the robot is identified using a set of presupposed parameters by taking input and output transmission index as the performance evaluation criteria.
基金supported by the National ScienceFoundation for Distinguished Young Scholars(51925301)the National Natural Science Foundation of China(52122315 and 21972008)+3 种基金Beijing Nova Program(Z201100006820021)the Fundamental Research Funds for the Central Universities(XK1902)the Wanren Plan(wrjh201903)the Open Project of State Key Laboratory(sklssm2022)。
文摘Micro-light emitting diode(micro-LED)is an emerging display technology with excellent performance of high contrast,low power consumption,long lifetime,and fast response time compared with the current display(e.g.,liquid crystal and organic LED(OLED)).With technological advantages,micro-LED holds promise to be widely applied in augmented reality(AR),flexible screens,etc.and is thus regarded as the next generation of display technology.In the process flow of micro-LED,the step known as mass transfer that requires transferring millions of micro-LEDs from a growth substrate to a display plane,is one of the key challenges limiting the commercialization of micro-LED from laboratory.Worldwide academic and industrial efforts have been devoted to developing mass transfer strategies with purposes of improving yield and reducing cost.Herein we review three main categories of mass transfer technologies for micro-LED display(pick-and-place,fluid self-assembly and laser-enabled advanced placement)and the coupled detection and repair technologies after transfer.Discussions and comparisons have been provided about the underlying general principle,history,and representative parties,advantages,and disadvantages(yield/efficiency/cost)of these technologies.We further envision the application prospect of these transfer technologies and the promise of the future display of micro-LED.
