A Practical Application of an On-orbit Instrumentation System for Model Verification of a Large Flexible Spacecraft

The model verification of large flexible spacecraft is a new field of experimentation that expands the envelope of instrumentation systems wilh heretofore unseen performance and environmental demands. This paper will describe the hardware and software implementation of an on-orbit instrumentation system to be flown on the International Space Station (ISS) for the purpose of gathering structural response data on-orbit for usa in model verification of the fully integrated space station structure. The Structural Dynamic Measurement System (SDMS) is comprised of 33 accelerometers, 38 strain gage bridges, and two signal conditioning units externally mounted and distributed along the main truss of the ISS. The output from the sensors is processed through the ISS Command and Data Handling (CBDH) system and telemetered to the ground for data reduction using the Eigensystem Realization Algorithm (ERA). The implementation of SDMS on the ISS has required new sensor construction and installation techniques never before used in order to provide an instrumentation system that will survive the hostile environment of space for a prolonged period of time. Many discussions have been provided on the analytical reduction of data for n-ode1 verification of the ISS. but little work has been published addressing the physical implementation of such an instrumentat ion system.