Under-actuated release control method based on nonlinear space tether system

Abstract

The invention provides an under-actuated release control method based on a nonlinear space tether system. The method comprises the following steps: 1, a dumbbell model is adopted, system dynamics differential equations are built according to a second kind Lagrange equation, and a dimensionless form is introduced in the differential equations; 2, based on a normal form expression for the above dynamics differential equations, expected values for a system in-plane pitching angle and an out-plane rolling angle are set, and the balance position of the system in the release process is obtained; 3, starting from the balance position of the system, a tether length change control law for realizing tether release is deduced and obtained; and 4, the range for the expected in-plane pitching angle is determined to ensure the tether release process to be asymptotically stable under effects of the control law. Numerical simulations show that the space tether can be released asymptotically stably under effects of the release control method provided by the invention, and an attractor capable of covering the balance point and an attraction domain with enough thickness can be found out.

Description

technical field [0001] The invention relates to the field of spacecraft control, in particular to an underactuated release control method for a nonlinear space tether system, and can prove that the method is globally stable. Background technique [0002] Space tether release technology has received extensive attention from scholars. For example, Barkow et al. compared the release control effects of various methods such as brake control, Kissel control, and optimal control on tethered satellites. Tanaka et al. designed a set of open-loop control laws for a type of micro-tethered satellite, which can effectively suppress the in-plane pitch angle of the tether during release. Williams constructed the nonlinear dynamic equation of the six-degree-of-freedom tethered satellite, and achieved the optimal release / recovery control of the tether by adjusting the tension, but it caused a large tether swing during the period. Taking into account the rigid-flexible coupling effect, Yu e...

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Problems solved by technology

[0003] By paying attention to previous research results, it can be found that the optimal release control strategy of the tether represented by the optimal path or time, the control process usually causes a large oscillation of the tether, and consumes a lot of computing time; the optimal release control strategy represented by Kissel control Pull or rope length control strategies are usually only applicable to circular orbits around the earth, and can only suppress the in-plane pitch and swing angle; moreover, the general radial release control does not fully consider the perturbation factors, and lacks global stability analysis

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