Sine Test Preparation & Management Involving a Large Number of Channel Counts

Abstract eng:
Bepi Colombo represents an ESA corner stone mission in collaboration with JAXA in Space science and exploration. The purpose of the mission is to fly two (2) planetary orbiters to Mercury with the aims of magnetospheric and planetary surface mapping. The paper presented here is intended to convey to the wider community considerations and experiences relating to both preparing and conducting a sine test with a large acquisition count. The test specimen comprises of a stack of three Spacecraft modules: a propulsion Spacecraft at the launcher interface and two (2) planetary orbiters stacked one on top of the other. The total test specimen mass was 6400kg comprising 3900kg (structure), 2400kg (test adapter) with the remaining mass allocated to a Force Measurement Device (FMD) and ancillaries. Over 512 channels were instrumented (441 accelerometers, 69 strain gauges, 6 FMD channels) along with a further 49 Virtual Channels combining physical acquisitions to produce angular accelerations, direct force outputs, local bending moment outputs (both from strain gauges) to enable management of sine input levels and monitor integrity of the structure. During pre-test preparation, activity is focused towards preparation of the test technical management plan whose purpose is to define a justification for sine input levels, how the test is to be managed in terms of technical strategy and collation / establishment of the acceptable upper and lower limits which the test must achieve and not exceed to avoid compromising the structural specimen. The paper also discusses preparation of the test support tool and highlights a number of points including factors such as the need to validate data phase acquisition checks. Simulation (dry runs) of on-test activities is seen as critical to a successful test to ensure that the process is robust, tools/software are adequately de-bugged and ensuring the data analysis team responsibilities are well understood. For the Bepi Colombo sine test campaign Astrium deliberately maintained the same acquisitions during each axis of sine test, thus trading complexity of data analysis versus improvement in acquisition management. Typically re-configuration of acquisitions between sine test axes is accompanied by a number of re-patching issues which is discussed further in the paper. Using in-house tools written into DYNAWORKS, Astrium confidently managed the large number of acquisitions and data analysis successfully within the tight timeframes imposed during such campaign. The paper concludes with a discussion of the lessons learnt covering both successes and areas for future improvement for the final flight model sine test campaign.

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