The tethered TSAR(tomographic synthetic aperture radar)system is a group of tethered SAR satellites that can be rapidly deployed and provide a stable baseline for 3-dimensional topographic mapping and moving target de...The tethered TSAR(tomographic synthetic aperture radar)system is a group of tethered SAR satellites that can be rapidly deployed and provide a stable baseline for 3-dimensional topographic mapping and moving target detection.Successful deployment is critical for TSAR tethered system.This paper discusses the deployment strategy for a 3-body chain-type tethered satellite system in a low-eccentric elliptical orbit.Two deployment strategies are discussed.Then,the tension on the tether is used to deploy it to the desired length and suppress its sway motion,resulting in an underactuated and input-constrained system.Hierarchical sliding mode control(HSMC)with anti-windup technology is employed to overcome the above challenges.In addition,the proposed approach includes the use of a disturbance observer to estimate the second derivative signal and a robust differentiator to estimate the sliding surfaces of the unacted subsystem.Finally,the effectiveness of the proposed deployment strategy is verified by MATLAB/Simulink.展开更多
To efficiently plan the point-to-point path for a 7-degrees-of-freedom(7-DOF)free-floating space manipulator system,a path planning method based on Legendre pseudospectral convex programming(LPCP)is proposed.First,the...To efficiently plan the point-to-point path for a 7-degrees-of-freedom(7-DOF)free-floating space manipulator system,a path planning method based on Legendre pseudospectral convex programming(LPCP)is proposed.First,the non-convex dynamics are approximated by utilizing the first-order Taylor expansion in the vicinity of the initial guess path,which results in a convex system.Next,the linearized dynamics are discretized at Legendre-Gauss-Lobatto collocation points to transcribe the differential equations to a set of equality constraints.To obtain a reliable initial guess trajectory,the auxiliary path planning problem of the 7-DOF space manipulator with a fixed base is initially resolved.Additionally,the penalty function method is introduced to enhance the convergence performance of the LPCP.Finally,simulation results show that the proposed algorithm in this paper can generate the point-to-point path and has higher computational efficiency than the general sequential convex programming method while ensuring optimality.展开更多
基金sponsored by the National Natural Science Foundation of China(grant number 62173273)the Natural Science Basic Research Plan in Shaanxi Province of China(grant number 2020JC-19).
文摘The tethered TSAR(tomographic synthetic aperture radar)system is a group of tethered SAR satellites that can be rapidly deployed and provide a stable baseline for 3-dimensional topographic mapping and moving target detection.Successful deployment is critical for TSAR tethered system.This paper discusses the deployment strategy for a 3-body chain-type tethered satellite system in a low-eccentric elliptical orbit.Two deployment strategies are discussed.Then,the tension on the tether is used to deploy it to the desired length and suppress its sway motion,resulting in an underactuated and input-constrained system.Hierarchical sliding mode control(HSMC)with anti-windup technology is employed to overcome the above challenges.In addition,the proposed approach includes the use of a disturbance observer to estimate the second derivative signal and a robust differentiator to estimate the sliding surfaces of the unacted subsystem.Finally,the effectiveness of the proposed deployment strategy is verified by MATLAB/Simulink.
基金supported by the National Natural Science Foundation of China(grant no.11972182)the Science and Technology on Space Intelligent Control Laboratory(nos.HTKJ2022KL502014 and 2021-JCJQ-LB-010-08).
文摘To efficiently plan the point-to-point path for a 7-degrees-of-freedom(7-DOF)free-floating space manipulator system,a path planning method based on Legendre pseudospectral convex programming(LPCP)is proposed.First,the non-convex dynamics are approximated by utilizing the first-order Taylor expansion in the vicinity of the initial guess path,which results in a convex system.Next,the linearized dynamics are discretized at Legendre-Gauss-Lobatto collocation points to transcribe the differential equations to a set of equality constraints.To obtain a reliable initial guess trajectory,the auxiliary path planning problem of the 7-DOF space manipulator with a fixed base is initially resolved.Additionally,the penalty function method is introduced to enhance the convergence performance of the LPCP.Finally,simulation results show that the proposed algorithm in this paper can generate the point-to-point path and has higher computational efficiency than the general sequential convex programming method while ensuring optimality.
