| 2 | Extended DMPs Framework for Position and Decoupled Quaternion Learning and Generalization显示文摘Dynamic movement primitives(DMPs)as a robust and efcient framework has been studied widely for robot learning from demonstration.Classical DMPs framework mainly focuses on the movement learning in Cartesian or joint space,and can’t properly represent end-efector orientation.In this paper,we present an extended DMPs framework(EDMPs)both in Cartesian space and 2-Dimensional(2D)sphere manifold for Quaternion-based orientation learning and generalization.Gaussian mixture model and Gaussian mixture regression(GMM-GMR)are adopted as the initialization phase of EDMPs to handle multi-demonstrations and obtain their mean and covariance.Additionally,some evaluation indicators including reachability and similarity are defned to characterize the learning and generalization abilities of EDMPs.Finally,a real-world experiment was conducted with human demonstrations,the endpoint poses of human arm were recorded and successfully transferred from human to the robot.The experimental results show that the absolute errors of the Cartesian and Riemannian space skills are less than 3.5 mm and 1.0°,respectively.The Pearson’s correlation coefcients of the Cartesian and Riemannian space skills are mostly greater than 0.9.The developed EDMPs exhibits superior reachability and similarity for the multi-space skills’learning and generalization.This research proposes a fused framework with EDMPs and GMM-GMR which has sufcient capability to handle the multi-space skills in multi-demonstrations. | Zhiwei Liao Fei Zhao Gedong Jiang Xuesong Mei | 2022 | Chinese Journal of Mechanical Engineering2022，35，4： | 0 |
| 3 | VERTICAL NONCONTACT POSITIONING H_∞ ROBUST CONTROL FOR MAGNETICALLY LEVITATED SURFACE MOTOR显示文摘To fulfill the stringent requirement,super-precision positioning and ultra cleanness,a surface motor with the integrated chip fabrication equipment is constructed by using permanent magnets and electromagnet coils as primary actuating components. It consists of stator and mover,and the mover is isolated from the stator by the magnetic bearing. The magnetic bearing in the stator is composed of eight air core electromagnet coils,the propulsion in the stator is composed of iron core and electromagnetic coils,and the mover is composed of NdFeB permanent magnets and levitated stage. Based on Lorentz law,some parameters,including permanent magnets dimensions,currents and levitation height,which may affect the stability,are analyzed and optimized. To improve the positioning accuracy in the vertical direction of the magnetic levitation surface motor,a robust controller is proposed using H∞ mixed sensitivity control theory. The simulation results show that by choosing appropriate weight functions,the controller can ensure the robustness of the closed loop system under the presence of uncertainties,and the H∞ robust controller is excellent for reducing steady error and increasing response speed. | TAO Tao HAO Xiaohong MEI Xuesong JIANG Gedong ZHANG Dongsheng | 2008 | Chinese Journal of Mechanical Engineering2008，21，1： | 0 |
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