A Novel Automatic Multi-point Multi-channel Shunt Calibration System for Field Calibration of Strain-gauge Based Transducers in Time Critical Applications

摘要

Static testing of aerospace propulsion systems requires extensive instrumentation where a number of strain gauge based transducers are used to measure pressure, thrust and strain for performance evaluation, qualification and acceptance of these systems. Conventional method of field calibration of these transducers by bringing the standards to the test bed is time consuming, cumbersome, error prone and sometimes not at all feasible. As an effective alternative, we have conceptualized a novel automatic multi-point multi-channel shunt calibration system for field calibration. Prototype of a microcontroller based automatic shunt calibration system (ASCS) has been designed, developed and tested to prove the concept. We have carried out 3/5/7/11 point shunt calibration of up to 16 channels. Maximum error in calibration was found to be 0.888% of full scale output. This has enabled us to automate the complete field calibration process and reduce the overall calibration time by more than 90% with respect to the manual process, thereby making it preferable for time critical applications. The system can be modified for further reduction in calibration time, improvement in accuracy and increase in channel count.