A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of...A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of the paraboloidal primary mirror,the mirror is discretized into equal thickness shell elements by considering shell curvature.And the material nonlinear constitutive relation of flexible mirror is acquired using Absolute Nodal Coordinate Formulation(ANCF).Furthermore,the primary mirror of F-DST can be regarded as a clustered multi-body system,and its dynamic equations of elastic deformation and deployment motion are established by virtual work principle.Finally,the deployment motion of primary mirror by different driving conditions are simulated,the results show that the vibrations of mirrors that driven by elastic hinge device are more than that driven by servo motor.In addition,single sub-mirror deployment process will perturb the pointing accuracy of primary mirror,and the multiple sub-mirrors simultaneously deploying will seriously affect all the sub-mirrors surface accuracy because of the coupling effect.Thus,there are theoretical value and practical significance for the controlling surface accuracy and attitude accuracy of space telescope.展开更多
In this study,we investigate the automatic docking of an electric tractor with a semi-trailer in narrow and longdistance scenarios.We propose an automatic docking method based on a multi-sensor fusion high-precision p...In this study,we investigate the automatic docking of an electric tractor with a semi-trailer in narrow and longdistance scenarios.We propose an automatic docking method based on a multi-sensor fusion high-precision positioning algorithm and a multi-strategy docking control algorithm.To solve the heading-angle error of the involved camera due to mechanical errors,a compensation value in the form of angle deviation is introduced.To alleviate the increase in the camera detection error with longitudinal distance,a piecewise coordinate compensation function is proposed.Repositioning is performed using light detection and ranging(Lidar)to improve the pose-perception accuracy to the millimeter level.To avoid the interference of point clouds on the relocation accuracy of Lidar,a search-and-location method that combines both small and large neighborhoods is proposed.To achieve the desired docking success rate,a multi-strategy-adjustment control algorithm is used to enable comprehensive adjustment,including approximate control of the maximum angle based on lateral deviation and fine proportional-integral-differential(PID)control based on lateral deviation and longitudinal distance,security check cycle and premature warning mechanism,and risk avoidance control.Finally,the reliability and stability of the design scheme are verified by conducting multiple experiments involving actual vehicles.展开更多
基金based on Project 51575126 the National Natural Science Foundation of ChinaProjects 2013M541358 and 2015T80358 the China Postdoctoral Science Foundation。
文摘A nonlinear dynamic modeling method for primary mirror of Flower-like Deployable Space Telescope(F-DST)undergoing large deployment motion is proposed in this paper.To ensure pointing accuracy and attitude stability of the paraboloidal primary mirror,the mirror is discretized into equal thickness shell elements by considering shell curvature.And the material nonlinear constitutive relation of flexible mirror is acquired using Absolute Nodal Coordinate Formulation(ANCF).Furthermore,the primary mirror of F-DST can be regarded as a clustered multi-body system,and its dynamic equations of elastic deformation and deployment motion are established by virtual work principle.Finally,the deployment motion of primary mirror by different driving conditions are simulated,the results show that the vibrations of mirrors that driven by elastic hinge device are more than that driven by servo motor.In addition,single sub-mirror deployment process will perturb the pointing accuracy of primary mirror,and the multiple sub-mirrors simultaneously deploying will seriously affect all the sub-mirrors surface accuracy because of the coupling effect.Thus,there are theoretical value and practical significance for the controlling surface accuracy and attitude accuracy of space telescope.
基金supported by the National Natural Science Foundation of China(52175007/52175012)the Yangtze River Delta HIT robot technology research institute(HIT-CXY-CMP2-ADTIL-21-01)+1 种基金the China Postdoctoral Science Foundation(2018M630348)the Self-Planned Task(SKLRS202005B)of State Key Laboratory of Robotics and System(HIT).
文摘In this study,we investigate the automatic docking of an electric tractor with a semi-trailer in narrow and longdistance scenarios.We propose an automatic docking method based on a multi-sensor fusion high-precision positioning algorithm and a multi-strategy docking control algorithm.To solve the heading-angle error of the involved camera due to mechanical errors,a compensation value in the form of angle deviation is introduced.To alleviate the increase in the camera detection error with longitudinal distance,a piecewise coordinate compensation function is proposed.Repositioning is performed using light detection and ranging(Lidar)to improve the pose-perception accuracy to the millimeter level.To avoid the interference of point clouds on the relocation accuracy of Lidar,a search-and-location method that combines both small and large neighborhoods is proposed.To achieve the desired docking success rate,a multi-strategy-adjustment control algorithm is used to enable comprehensive adjustment,including approximate control of the maximum angle based on lateral deviation and fine proportional-integral-differential(PID)control based on lateral deviation and longitudinal distance,security check cycle and premature warning mechanism,and risk avoidance control.Finally,the reliability and stability of the design scheme are verified by conducting multiple experiments involving actual vehicles.
