ROBUST CONTROL OF SATELLITE WITH FUEL SLOSH INSTABILITIES

摘要

This paper presents an H_∞ design methodology for fuel slosh control in telecom satellites in Orbit Raising Mode (ORM) (i.e. apogee boost to reach geosynchronous orbit). This study focuses on a spacecraft with flexible Solar Arrays (SAs) and fuel sloshing modes located close to the control cut-off frequency. Because one of the sloshing modes is non positive (the Nichols chart of the open-loop has a left-rotating cycle), phase control is required to ensure robust stability despite high uncertainties on modeling parameters. We present an H_∞ design scheme with explicit phase-lead tuning through a dedicated weighting filter. It uses the passivity property, which ensures that the open-loop transfer is positive-definite when the H_∞ norm of the sensitivity function S - T stays lower than 1. The last section shows the computed controllers, the open-loop charts, stability margins and performance.