Vibration Tests of a Spacecraft via a Switched Robust Controller-based Virtual Shaker

This paper considers the control of spacecraft's vibration testing system. This test system is used for the qualification of the dynamic behavior of spacecraft under severe launch environment. The vibration testing system shall cover the launcher's vibration frequency band with respect to the spacecraft limitations (notching around the eigen frequencies). Several control strategies were already studied, leading however to inaccurate tracking performance and important oscillations due to the excitation of the vibrational modes of the spacecraft. An additional difficulty results from the large spectral interval tracking problem, generally beginning at 5 Hz, and continuing up to 150 Hz. In this paper, a switching control strategy is developed based on several robust controllers, where the switch between controllers depends on the reference frequency. The performance of this strategy is assessed by means of a model in- the-loop (MIL) architecture introduced for the virtual shaker testing campaign up to 40 Hz, including Monte-Carlo simulations. Moreover, the campaign's security is assured through guaranteed stability margins of the closed-loop system, limiting the testing campaign to a single run vibration testing instead of the current four-stage one, reducing the testing cost.