Design of a soft sensor for thermal data of test object during thermal cycling test at CATVAC

Comprehensive Assembly and Test Thermo Vacuum Chamber (CATVAC) facility is used for performing thermo vacuum performance test and thermal cycling tests on spacecraft and spacecraft appendages. The thermal system consists of a thermal shroud as an active element and test object as the passive one. Thermal cycling test profiles are temperature profiles of ramp and dwell on the test object with the process value control channel on it. The failure of the control system input thermocouple on the test object can disturb the control process. The designed soft sensor can infer the temperature of the control thermocouple channel from other measurements and provide redundancy to the physical channel. Archived thermal data was used for generating a process model with measurement channels as input and control channel value as output. The model input data was selected by studying their correlation to existing control channel measurements. The selected data was checked for validity using statistical method. The model output was obtained with another set of input data and validated by comparison with actual sensor values. The result shows excellent matching of soft sensor values to that of actual sensor.