A 2-DOF drag-free control ground simulation system based on Stewart platform

Area of Science:

• Space physics
• Astrophysics
• Control systems engineering

Background:

• Space-based gravitational wave missions require picometer-level precision displacement measurements between distant test masses.
• Drag-free control is essential for maintaining the ultra-static and ultra-stable experimental platforms needed for these missions.

Purpose of the Study:

• To propose and validate an innovative ground simulation scheme for drag-free control principles using a Stewart platform.
• To design and test a robust drag-free controller for space applications.

Main Methods:

• Kinematics and dynamics modeling of a Stewart platform.
• Design and construction of a drag-free ground simulation experimental setup.
• Development of a two-degree-of-freedom (2-DOF) drag-free controller using H-infinity loop shaping algorithm.
• Semi-physical simulation experiments employing rapid control prototyping technology.

Main Results:

• The H-infinity controller demonstrated superior performance over a PID controller in simulations.
• Experimental results confirmed the drag-free control algorithm's effectiveness, reaching the hardware's limit accuracy.

Conclusions:

• The proposed Stewart platform-based ground simulation scheme is effective for drag-free control.
• The developed H-infinity controller successfully meets the stringent requirements for space-based gravitational wave detection missions.