Deployment control method for space tether system based on nonlinear model predictive control

Abstract

The invention provides a stable control method for the deployment of a three-dimensional space tether system operating in a near-Earth elliptical orbit at the initial stage. Only by adjusting the limited tension of the tether, without relying on other propellers, the tether is released to the desired length and restrained. The swing of the tether. The method includes the following steps: S1. Establishing a two-body space tether system dynamics model considering the quality of the tether; S2. Under the conditions of considering uncertainties such as disturbance, underactuation, tether swing angle and tether tension , based on the nonlinear model predictive control (NMPC) algorithm, the original nonlinear model is discretized by using the pseudo-spectral algorithm, and the open-loop optimal problem in predictive control is transformed into a nonlinear programming problem for solution. S3. Determine the control quantity of the next control cycle according to the solution of the nonlinear programming problem to form a closed-loop control. Finally, the three-dimensional space tether system that operates in the near-Earth elliptical orbit is stably released and deployed in the initial stage.

Description

technical field [0001] The invention relates to a method for controlling deployment of a space tether system, and belongs to the technical field of space tether system applications. Background technique [0002] The space tether system refers to a combination of man-made space objects that are connected together by tethers to complete in-orbit flight. The tether is connected to another aircraft with a larger mass (the main star), forming a space combination of the main star-tether-sub-star. The main star can be a variety of space vehicles such as satellites, spaceships, space shuttles, and space stations, or even abandoned final-stage launch vehicles; the sub-stars can be small satellites, return capsules, and micro-probes. [0003] The complex space tether system is composed of multiple space objects, and they are connected into closed loops, trees or polyhedrons with tethers. The space tether system is a new type of structure built by people in space, which can complete ...

AI Technical Summary

Problems solved by technology

[0004] Because the space tether deployment control system is affected by space perturbation, it is very easy to generate complex tether vibration problems. At the same time, the system is not only a nonlinear, typical underactuated system, but also subject to some physical constraints, such as the pulling force is always positive and has an upper limit. , these bring difficulties to the design of the controller

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