Control performance simulation and tests for Microgravity Active vibration Isolation System onboard the Tianzhou-1 cargo spacecraft

The Microgravity Active vibration Isolation System (MAIS), which was onboard China’s first cargo-spacecraft Tianzhou-1 launched on April 20, 2017, aims to provide high-level microgravity at an order of 10 -5 –10 -6 g for specific scientific experiments. MAIS is mainly composed of a stator and a floater, and payloads are mounted on the floater. Sensing relative motion with respect to the stator fixed on the spacecraft, the floater is isolated from vibration on the stator via control forces and torques generated by electromagnetic actuators. This isolation results in a high-level microgravity environment. Before MAIS was launched into space, its control performance had been simulated on computers and tested by air-bearing platform levitation and aircraft parabolic flight. This article first presents an overview of the MAIS’s hardware system, particularly system structure, measurement sensors, and control actuators. Its system dynamics, state estimation, and control laws are then discussed, followed by the results of computer simulation and engineering tests, including the test of the six-degree-of-freedom motion by aircraft parabolic flight. Simulation and test results verify the accuracy of the control strategy design, effectiveness of the control algorithms, and performance of the entire control system, paving the way for operation of MAIS in space. This article also presents the steps recommended for the control performance simulation and tests of MAIS-like devices. These devices are expected to be used on China’s Space Station for various scientific experiments that require a high-level microgravity environment.