Krenn, Rainer

Landzettel, Klaus

English

Institute of Transport Research:Publications

Modeling and Simulation of Satellite Docking Using MBS-Compatible Contact Dynamics ToolsRainer Krenn, Klaus Landzettel German Aerospace Center (DLR), Institute of Robotics and Mechatronics Oberpfaffenhofen, D-82234 Wessling, Germany 1st ESA Workshop on Multibody Dynamics for Space Applications, 2 – 3 February 2010, ESA/ESTEC, Noordwijk21st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Contents of PresentationModified Elastic Foundation contact modelapplied for satellite docking simulationswithin MBS based simulatorsContact dynamics modelingContact surface generationContact detectionContact force computationSimulationResults (examples from Smart-OLEV)Verification31st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Satellite Capturing Method for OLEV 41st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Contact Surface Generation - MeshingContact bodies = rotational bodiesSurface shape defined by longitudinal profile: r = f(z)Sampling point distribution is function of Gaussian curvatureMeshing by rotation of profileVertices, triangular facesSurface normals, area size...51st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Contact Detection AlgorithmMapping of surface verticesTransformation of vertices into body reference frame of reference body3D Cartesian (x,y,z) → 2D cylindrical (r,z)Reference body: ProfileContact body: Point cloudContact detection based on comparison of radial co-ordinatesConvex/convex and concave/convex contact problemsMulti-point contactVariable profile61st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Hierarchical Boundary SurfacesFace simplification ratio 4:1 (number of faces = 4n)Speed-up of contact detectionReduction of computational loadconcave contact surface convex contact surface 14166471st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Contact Patch Generation with RefinementContact faces: 3 of 3 vertices per face in contactAmbiguous contact faces: 1 or 2 of 3 vertices per face in contactRefinement of patch border (sub-faces)Re-call of contact detection for sub-face verticesSmooth force signals important for fast MBS solver progress   81st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Contact Kinematics of Contact PatchMapping of contact shape faces onto reference bodyRelative motion states between well-defined polygon pairsFor each contact polygon:Contact surface penetration depth sn → normal contact force (linear spring)Normal penetration velocity vn (compression, decompression) → normal damping force (linear damper)Tangential contact velocity vt → Coulomb friction force (slip) Track of contact location P → Coulomb friction force (stick) 91st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Contact Force Computation Elastic Foundation Model       0;11 1 2,: Specific normal contact force: Normal contact penetration depth: Normal contact penetration velocity: Young's modulus of elastic layer: Poisson ratio n n nn nnnnf Ks DvEKbD D T b s H vfsvE      0of elastic layer: Areal damping coefficient of elastic layer: Elastic surface layer thicknessDbTwo rigid bodiesOne surface covered with thin elastic layerDefinition of contact dynamics properties101st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Friction Force Computation (Stick-Slip): Specific fristickt tstick slipstickswitch switchswitchtswitcht tstick slip nswitch switchtslip ntsticks vstickslips vstatev stickslip vv slips vstick fs vfslip ff                               /ction force: Specific normal contact force: Coulomb friction coefficient for stick/slip: Friction strain (stick): Friction velocity: Max. friction strain (stick): Min. snstick slipttswitchswitchfsvsvlip velocity111st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010Multibody System for Satellite DockingClientHot Bird series, with flexible solar wingsOrbit: GEOAOCS deactivated, momentum wheels loadedAerojet/Marquardt R4D nozzle, tilted1194 mm launch adapterSmart-OLEVOrbit: GEO + 2.178 m (R-bar)AOCS active75 mm lateral misalignment, 2° orientation error in all axesFlexible Capture Tool deployment mechanism0 ... ± 4 mm/s deployment/retraction velocityCapture ToolRadial laser distance sensorContact switchesOperational Locking CrownContact sensitive bodies:Nozzle vs. Capture Tool + Locking CrownLaunch adapter vs. Client Support Brackets Smart-OLEVClient Sup. BracketsFlexible BoomCapture ToolNozzleLaunch AdapterClient Spacecraft121st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010131st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010141st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 20100 50 100 150 200 250 300-200-1000100200300400Simulation Time [s]Applied Force [N]Locking CrownLocking Crown RFW02xyz0 50 100 150 200 250 300-5051015Simulation Time [s]Applied Torque [Nm]Locking CrownLocking Crown RFW02xyz0 50 100 150 200 250 300-0.06-0.05-0.04-0.03-0.02-0.0100.010.020.03Simulation Time [s]Lateral Position Error [m]Client COM - Smart COMSmart GRFW02yz0 50 100 150 200 250 300-0.0100.01Simulation Time [s]Elastic Deformation [-]CDM SegmentsBendingW020 50 100 150 200 250 300-505x 10-3Simulation Time [s]Elastic Deformation [-]CDM SegmentsTorsionW020 50 100 150 200 250 300-50510x 10-3Simulation Time [s]Elastic Deformation [m]CDM SegmentsAxialW020 50 100 150 200 250 300-100-50050Simulation Time [s]Applied Force - CSB 1 [N] W020 50 100 150 200 250 300-100-50050Simulation Time [s]Applied Force - CSB 2 [N] W020 50 100 150 200 250 300-100-50050Simulation Time [s]Applied Force - CSB 3 [N] W02151st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 20100 50 100 150 200 250 3000246x 10-4Simulation Time [s]Contact Penetration - Nozzle [m]W02CT BodyLC WireLC Bolt0 50 100 150 200 250 3000123x 10-3Simulation Time [s]Contact Size - Nozzle [m2]W02CT BodyLC WireLC Bolt0 50 100 150 200 250 300050010001500Simulation Time [s]Number of Contact Polygones - Nozzle [-]W02CT BodyLC WireLC Bolt0 50 100 150 200 250 300024x 10-4Simulation Time [s]Contact Penetration - Adapter [m]W02CSB 1CSB 2CSB 30 50 100 150 200 250 3000246x 10-4Simulation Time [s]Contact Size - Adapter [m2]W02CSB 1CSB 2CSB 30 50 100 150 200 250 300050100150Simulation Time [s]Number of Contact Polygones - Adapter [-]W02CSB 1CSB 2CSB 3Verification of Simulation ResultsElastic Foundation Model valid? → Maximum contact penetration depthContact area resolution sufficient? → Number of contact polygons161st ESA Workshop on Multibody Dynamics for Space Applications, Rainer Krenn, 3 Feb 2010New EPOS @ DLR GSOC

Modeling and Simulation of Satellite Docking Using MBS-Compatible Contact Dynamics Tools

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