Optimal Control Design Using an H2 Method for the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT)

Abstract

The acceleration environment on the Intern ational Space Station (ISS) will likely exceed the requirements of many micro-gravity experiments. The Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) is being built by the NASA Marshall Space Flight Center to attenuate the nominal acceleration environment and provide some isolation for microgravity science experiments. G-LIMIT uses Lorentz (voice-coil) magnetic actuators to isolate a platform for mounting science payloads from the nominal acceleration environment. The system utilizes payload acceleration, relative position, and relative orientation measurements in a feedback controller to accomplish the vibration isolation task. The controller provides current commands to six magnetic actuators, producing the required experiment isolation from the ISS acceleration environment. This paper presents the development of a candidate control law to meet the acceleration attenuation requirements for the g-LIMIT experiment platform. The controller design is developed using linear optimal control techniques for frequency-weighted H 2 norms. Comparison of the performance and robustness to plant uncertainty for this control design approach is included in the discussion.

Finite-time adaptive control for microgravity vibration isolation system with full-state constraints

“…Wu et al [15] proposed a double closed-loop control strategy composed of an absolute movement controller and a relative movement controller, and designed a low-pass filter and a band-pass filter to switch the control objectives. In addition, many studies have also transformed this problem into a multi-objective optimization problem, using H 2 [16,17], and hybrid multiobjective control [18,19] to achieve the control objectives. Furthermore, vibration isolation systems are usually characterized by nonlinearity and uncertainty.…”

Study on mixed H2/H∞output feedback control of maglev actuator for microgravity vibration isolation system

“…On this basis, Whorton 17 discussed the impact of different frequency weighting functions on the current and performance of a one-dimensional vibration isolation system. Calhoun and Hampton 18 applied the H 2 -optimal control to a 6-degree-of-freedom (DOF) microgravity vibration isolation system. Whorton 19 designed a 12-order mixed H 2 /H N mixed controller which displaced a 54-order H 2 controller for the 6-DOF microgravity isolation system.…”

<title>Survey of state-of-the-art vibration isolation research and technology for space applications</title>

“…Risk reduction flights for the technology have been made 71. Other efforts are being made to isolate individual experiments from the ISS 72,73,74,75. …”