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Nasa HDS
- 1. NASA Launch Vehicle Hydro-Dynamic Suspension System (HDS) Michael Sachs, System Engineer, NASA Marshall Space Flight Center
- 2. Agenda History of the HDS and IVGVT HDS Refurbishment and Design HDS Control Room HMI’s HDS System Architecture IEEE1588 PTP (GPS, UTC, TAI, DST) cRIO SCADA Reference Design
- 3. What is a Hydrodynamic Suspension System (HDS)?Integral part of IVGVT allowing meas. of vehicle modal characteristicsVerification of FEM, improve GN&C stability, identify resonance anomalies 7,200,000 lb Lifting cap. 6 Axis DOF to simulate Free-Free boundary flight conditions. Strategically placed electro-dynamic shakers simulate thrust oscillation and acoustic shock.
- 4. Saturn V in the Test Stand, circa 1966 Two people pushing on the nose cone or the fins on the first stage, could deflect the vehicle as much as two inches. Prior to the HDS, IVGVT was accomplished by suspending the vehicle with cables. Prohibitive due to weight limitations and cable resonance.
- 5. Original HDS testing, circa 1965Martin Marietta Engineers I wonder what a day around hydraulic oil does to a white shirt and tie?
- 6. Refurbished HDS Cylinder and PistonHydrodynamic Suspension System One year to refurbish 4 HDS, replacement cost > $1,000,000
- 7. HDS Piston and CylinderHydraulic Lift with N2 Gas Spring HPU SVU Unique Design: Nearly 100% inefficient but 100% effective! Why? Continuous Hydraulic flow through and across bearing surfaces.
- 8. Hydraulic Pump Unit and Sump Valve StandHydrodynamic Suspension System Interface to wide variety of analog and digital controls and sensors Motor Controls (4), Discrete Valves (24), Proportional Valves (10), Pressure (20), Temp (9), Flow (3), Discrete Inputs (45), RTD (3), Discrete Outputs (14)
- 9. Design Goals: Extensible Architecture supporting Distributed RT control 2. Workbook based Configuration (GXML based) 3. Instrumentation Management Tools a. Tag Properties: Scaling, Filtering, ZOFS, Initial Value, DB% b. Target Imaging c. HMI bindings
- 10. Design Goals: 24/7 Historical Data Logging (up to 20Hz) RT Target sync to GPS, timestamped +/- 1ms 6. Diagnostics a. Multi-Tiered Alarm b. RT process Monitor c. Syslog, DSM 7. Safety/Reliability features (FMEA driven)a. Watchdog based ESTOP->Park b. Pump Dropout detection c. N2 pressure interlocks d. Bearing Contact monitor
- 11. HDS Instrumentation ManagerOne stop shopping for all your HDS configuration needs Overview of HDS networked devices, cRIO, HMI, PXI-6682
- 12. HPU HMI, Primary Operation Screen Pump Startup Sequencing, Tank Heater/Level, HE Temp Reg. +/- .2F, Filter Life Monitor
- 13. HDS HPU, Manual Pump Controls Touchpanel aware data entry, Tag ZOFS, Tag Stats Display
- 14. HDS HPU, Manual Pump Controls Touch Panel Numeric Data Keypad, activated by 2s touch on any control
- 15. HDS HPU, Manual Pump Controls HMI tag stats display, right click on any control or indicator
- 16. SVU HMI, Operate Screen Individual and sync’d HDS control, N2 Autocharge, DPH (Dynamic Piston Height Control) dPH/dt, DPH Mean, HDS state, Bearing Contact Monitor (transient and persistent)
- 17. HDS Software ArchitectureMVC (Model View Controller) Model – SVE/PSP interface supports NSV bindings, events, static/dynamic NSV access
- 19. IOV -> NSV binding preserves timestamp
- 20. +/- 100us RT system time, +/- 1ms data timestampcRIO PC Scan Engine IOV NSV NSV Data Timestamp Module Citadel TimeSync 1588 PTP Slave IEEE 1588 Ethernet GPS 1588 PTP Master TAI (1588) = GPS+19s UTC = TAI-34s PXI-6682
- 21. HDS Instrumentation ManagerWorkbook Configuration, Compile to GXML -> Target
- 22. DSM Historical Trend Capability Manual Shake Test, Natural HDS damping characteristic
- 23. DSM Historical Trend Capability New water chiller cycling disturbances
- 24. cRIO SCADA Reference Design Can be obtained at www.viScience.com Features: XLS/GXML Configuration Manager On-the-fly cRIOconfig. deployment Per channel SR, Filter, Scaling,DB, ZOFS HMI->cRIO Messaging (async and sync) Built-in TP Controls HMI Tag Management a. Creates NSV binding b. Creates embedded HMI Tag Desc. c. ZOFS apply/remove at tag Critical timing verification Syslog (UDP) CVT API
- 25. viScience.com
Editor's Notes
- So, what is an HDS? Well it is one of the underpinning technologies of IVGVT. Critical to establishing flight readiness for all NASA SLS. Provided sufficient confidence to permit humans to be aboard the Maiden flight of the Space Shuttle. So why did I include a picture of the ISS here.Of course it looks cool, But actually ISS mission control is at MSFC and every ISS component and Shuttle payload undergoes structural and environmental testing at MSFC.
- So, what is an HDS? Critical to establishing flight readiness for all NASA SLS. ISS component and Shuttle payload undergoes structural and environmental testing at MSFC.
- Most launch and space vehicles, as well as aircraft, undergo a low-energy vibration test to measure the modal characteristics of the vehicle. This modal testing or ground vibration testing (GVT) usually captures the natural frequencies, mode shapes, and damping of the vehicle’s structure. This data is then used to correlate dynamic finite element models (FEMs) to produce test-verified dynamic FEMs for use by disciplines such as aeroelasticity, structural loads and dynamics, and guidance, navigation and control (GN&C) to analyze, and estimate vehicle responses to expected flight, and ground loads and environments. Analyses employing the test-verified FEMs are used to support the design certification review (DCR) process, ensuring that the vehicle is structurally sound and safe to fly. Current analyses show the fundamental frequencies of a fully fueled, launch-ready Ares I launch vehicle to be in the 1 to 10 Hertz (Hz) range, giving the Ares I the lowest primary bending frequency of any human-rated launch vehicle that NASA has ever flown. Therefore, understanding the flex properties of this vehicle is especially important. By measuring the response to a known excitation at the precise location of the flight control sensors a significant amount of uncertainty can be removed from the sensed data processed by GN&C algorithms allowing improved flight control system performance. Furthermore, the IVGVT data can help fine-tune models used to optimize the performance of thrust oscillation mitigation and POGO suppression devices. Without test-calibrated IVGVT models, the model uncertainty factors (MUF) used in verification loads analysis are not updated and remain the more conservative values employed during earlier phases of the design. This can translate into flight envelope reduction and launch/payload restrictions. If model uncertainties are too large, GN&C stability requirements either cannot be met or make the design of the GN&C system more challenging. Model inaccuracies in the bending dynamics of the vehicle could create an unstable control system design, which in turn could result in loss of the mission. A GVT also supports GN&C analysis by reducing uncertainty in the flex model.
- The suspension system required to simulate free flight was a particular challenge. Suspending the vehicle by cables would not work, as the cables resonate at frequencies similar to that of the vehicle which might have complicated or invalidated test results. NASA developed a state-of-the-art suspension system to simulate the free-free boundary conditions of flight. The hydrodynamic support system or HDS consists of oil bearings and vertical gas springs for lateral and roll stability (Figure 2). Oil under pressure was pumped between flat contacting surfaces to provide a near-frictionless support. This system transmits the heavy vehicle load directly to the ground, enabling the support mass to be relatively small.9 The HDS units were so effective that the entire six- million-pound vehicle could be excited in its low frequency suspension modes by two people pushing the fins on the first stage, deflecting the vehicle as much as two inches.1
- NASA engineers circa 1965.
- Each HDS = 1.5 million lbs of lift capacity upon a ‘tuned’ gas spring with calculated N2 volume ‘stiffness’, natural freq. < 1/10 fundamental mode of vehicle (.6 Hz), Damping ~ 24 lb sec/in. Float Sunk Issues, detection, recovery procedure, Bearing contact sensing transient and static, float height measurement using delta p. Discuss upper and lower ring bearings and pressure monitoring/calibration. Mechanical safety features, Float seal prevent N2 blowby, Oil flow control prevent Estop setdown < 90s
- I remember when I first came to NASA, (What was it like to be there) even with much experience under my belt, the realization of the scale and criticality of the system that I was deisigning was giving me heart palptitations. (Our new National SLS was irreperably damaged due to software flaws in HDS control system). the But being able to work with such experienced and high caliber engineers particularly my good friende BB an expert in hydraulic systems provided great assurance that we had covered all faiolure modes. I had the luxury to be able to study several possible architectures ranging from PXI to cRIO. The utility of the cRIO with rugged design wide range of IO, scan engine / NSV technology, and supporting toools such as the DSC, Citadel DB, DSM were most compeling.
- Heat Exchanger with PID + Heat Load Balance Model (FF) + Adaptive SI (Recursive ARX)+/- .2F over wide range of operating conditions.
- If you have the model or ‘State’ of the system hosted in the SVE then you have created the heart of the MVC architecture. The PSP (Publish Subscribe Protocol) is the underlying technology in the SVE and provides an API to manage SV libraries, SVE transactions, SV bindings, SV events, etc. With the PSP, multiple client app’s or ‘Views’ can subscribe to collections of data tags in the system.
- GPS Publishes GPS time with UTC offset
- PLEASE USE THIS AS YOUR LAST SLIDE IN YOUR NIWeek PRESENTATION