HighResolution Standard Proximity Sensor . RogerBlaser Abstract TheHigh-Resolution Standard Proximity Sensor (HRSPS) isatruecontact-less eddycurrent displacement measuring system qualified forhigh-reliability satellite applications. Itisalsoavailable inan 883Bflightversion formicro-gravity andfortheInternational SpaceStation (ISS).Threedifferent sensor sizescovering threemeasuring ranges upto9mm(0.35in)areavailable. TheHRSPS offerseither2 independent singleor1differential output(s) witharesolution of1nanometer. Thetemperature rangeis standard spaceflight(-55°Cto70°C)butthesensors haveprovision foroperation to-150°C (-238°F) for missions toMars.Thereliability figures oftheHRSPS are1.7millionhoursforISSapplications and2.5 millionhoursforthesatellite version. Itisoperating under+28VDC(withfuse)2Wor+15VDC1.5W. Thepowerconsumption inthesensorheadisbelow15mW.Thispaperpresents thetestresultsandthe finalconfirmation oftheperformances oftheHRSPS. TheHRSPS should become thestandard nanomeasuring system qualified forspacemechanisms operating inclosedloopcontrol. Itisdesigned inorder toaccepttheworstlauncher environment. Introduction ESAidentified aworld-wide requirement foraStandard High-Resolution Proximity measuring system with theaimofreplacing themultitude ofcustomized sensors usedsofarinscanning andpointing space mechanisms orrobotics applications. TheHRSPS canbeusedasameasuring system inaclosed-loop controlled mechanism providing thefeedback ontheposition actually realized. Thispaperpresents the finalperformance resultsoftheHighResolution Standard Proximity Sensor developed underaGSTP competitive contract forESAR&DcenterESTEC intheNetherlands. TheHRSPS isageneral-purpose displacement measuring system targeted tobecome thestandard displacement measuring system qualified forspace.TheHRSPS system, defined asDisplacement Measuring System DMS-134, consists ofanelectronic conditioner IQS-134 connected to2sensor headsTQ-47X operating ineithersingleor differential arrangement. TheHRSPS isaninductive sensorworking ontheeddycurrent principle. Itcan perform measurements inasingleordifferential sensorarrangement andcanalsobeusedasaproximity switch. During thedevelopment, emphasis wasplaced onadesign thatcaneasilybeadapted todifferent measurement tasksandranges. Itisabletomeetthehighest resolution requirements, toachieve agood overallaccuracy ortoprovide ahighmeasurement bandwidth. Thelong-term intention istoofferanew HRSPS hardware compatible withcommercial satellites electronics racks. Applications Mechanisms operated inclosed loopcontrol generally require sensors toprovide afeedback onthe position actually realized. Comparison withthedesired position thenallowsthederivation ofanimmediate correction ofanymispositioning leading tothesuperior performance ofsuchmechanisms. TheHRSPS offersdisplacement measurements inasingleordifferential arrangement. Oneoftheapplications ofthe HRSPS willbeinthemeasurement ofrotation, although itismoresuitedforlinearmeasurements. The HRSPS isalsoacandidate fortheactivedamping oftheISSCentrifuge rotor.Themajority ofsensor designs available industrially andinthelauncher fieldarenotreadily suitable forhighreliability space (satellite) applications. Typical ground orlauncher approaches areverydifferent intermsofmaterial selection, electronics qualification andreliability status. TheHRSPS hasbeendeveloped fromthe beginning forspaceapplications, takingintoaccount theexperience ofVibro-Meter inindustrial and spacehigh-pressure cryogenic sensors designforlaunchers. Vibro-Meter SA,Fribourg, Switzerland Proceedings ofthe36thAerospace Mechanisms Symposium, GlennResearch Center,May15-17,2002 NASA/CP--2002-211506 147