Environmental simulation platform and its application to geodesic instruments for a performance study

In this study, an environmental simulation platform (ETS-02) was constructed for high-precision geodesic instruments (e.g., absolute/relative gravimeters and inclinometers), to test the disturbances caused by environmental fluctuations. The outer layer of the platform was constructed with two sets of rectangular electromagnetic coils, which generated the required magnetic field when current was applied. The inner layer was a closed cabin in which radiators were distributed such that the temperature of the experimental space inside the cabin could be controlled, by energy exchange between the radiators and a thermal controller through the flowing liquid. A high-precision hexapod was used to simulate the tilt-related effect. The platform was capable of adjusting temperatures within a dynamic range of 0°C–70°C at a resolution of 0.01°C. The noise of the power-spectrum density when the cabin was set to room temperature was measured as 0.03°C/Hz1/2 at 1 mHz. The magnetic field simulation had a dynamic range of ±300 μT and stability of 20 nT. The resolution of the ground-tilt simulation was 1 arc s. The inner space of the platform had a volume of approximately 5 m3, which is sufficient for most types of instruments to be tested for a general environmental coupling effect. To illustrate the application of the platform, a dual-axis inclinometer was built and tested carefully with the platform, and the accuracy of the calibration factors was found to be significantly improved.