ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
428 Clutch Spring design was discussed together with actual fatigue problems that led to the resign ation of  implementation of this mechanism’s component. Eventually an assembly problem was described,  connected with the bottle -neck effec t on the Hammer Lock Pins  movement , possible to omit by careful  tensioning of the Wire Helix.  

The Hammering Mechanism achieved successful performance results  with power consumption kept at  relatively low level, below 1 W, which proves the rightness of the implemented design.   

References  

1. Gromov V.V.  et al.: The mobile penetrometer, a “mole” for sub- surface soil investigation. In Proc . of 7th  European Space Mechanisms and Tribology Symposium. 1997.   2. Richter L.  et al.: Development of the “Planetary Underground Tool” subsurface soil sampler for the Mars  Express “Beagle 2” Lander. Advanced Space Research, No. 8, pp. 1225- 1230. 2001.   3. Richter L., Krömer O.: Application of a Remote Controlled Hammering Drill from  Space to Deep Sea.  Oceans 2009 –  Europe, IEEE. doi: 10.1109/OCEANSE.2009.5278132.   4. Spohn T.  et al.: InSight: Measuring the Martian  heat flow using the Heat Flow and Physical Properties  Package (HP3). In Proc . of International Workshop on Instrumentation for Planetary Missions. 2012.   5. Lichtenheldt R., Schäfer B., Krömer O.: Hammering beneath the surface of Mars -Modeling and simulation  of the impact -driven locomotion of the HP3- Mole by coupling enhanced multi -body dynamics and  discrete element method. 58th Ilmenau Scientific Colloquium (IWK), Ilmenau, Germany, 2014 .  6. Grygorczuk J.  et al.: Technological Features in the New Mole Penetrator “Kret” . In Proc. of 13th European  Space Mechanisms and Tribology Symposium  ESMATS, Vienna,  2009.   7. Seweryn K.  et al. : Low velocity penetrators (LVP) driven by hammering action– definition of the principle  of operation based on numerical models and experimental tests. Acta Astr ., vol 99, pp. 303- 317.  8. Stoker  C. R. , Gonzales  A., Zavaleta  J. R.: Moon/Mars Underground Mole. NASA Tech. Conf., 2006.   9. Spohn T. et al.: MUPUS –A thermal and mechanical properties probe for the Rosetta lander Philae. Space  Science Reviews , (2007) 128: pp. 339– 362. DOI: 10.1007/s11214- 006-9081- 2  10. Grygorczuk J.  et al.: Advanced Mechanisms and T ribological Tests of the Hammering Sampling Device  CHOMIK. In Proc. of 14th European Space Mechanisms and Tribology Symposium  ESMATS,  Constance, 2011.   11. Grygorczuk J. et al.: High Energy and Efficiency Penetrator -HEEP. In Proc. of 15th European Space  Mechanisms and Tribology Symposium  ESMATS, Noordwijk, 2013.   12. Grygorczuk J. et al.: Mole Penetrator Driven by an Electromagnetic Direct Drive (EMOLE). In Proc. of  16th European Space Mechanisms and Tribology Symposium  ESMATS, Bilbao , 2015 .  13. Grygorczuk J.  et al.: Specialized Hybrid Rolling Bearings for Space Use –  Project ROLOKOS. In Proc.  of 16th European Space Mechanisms and Tribology Symposium  ESMATS, Bilbao , 201 5.
431 end, the EFT Facility at BATC  acquired dozens of tri-axial sensors  of varying capabilities , high quality inline charge amplifiers, signal conditioners,  and a large number  of input/output multichannel, high  resolution and high dynamic range analog DAQ cards. The hardware for developing FMPs is modular so  that the right equipment is selected to support  single or multiple setups at a time.  The tool kit to allow  quick FMP  implementation and currently allows for measurement magnitudes ranging from 3E -5 N to 200  N, with h igher /lower  ranges possible. Multiple special EFT s tiff tables (Figure 1) provide a low 5- Hz  isolation system with a t op plate providing a standard 2- inch (5.1-cm) grid mounting pattern. Clean tents  with 15°C to 25°C  temperature control provide enclosures when stringent cleanliness or environmental  levels are required for flight hardware.  

Figure 1.  EFT tables with clean tents:  30,000 lb (60” x 60”) (left) and 4,400 lb (36” x 34”)  (right)          133 kN (1.5 m x 1.5 m) (left) & 19.6 kN (.91 m x .86 m) (right)   

The extent of stiffness verification of FMPs is performed first through analysis using a finite element model representing the load cells and encapsulating plates with and without the mechanism under test  and later, once assembled , using frequency response function testing. To ensure that the setup  configuration does not contribute to the measured data at particular frequency ranges, frequency  response functions are expected to have clean frequency responses. That is no gains  (or tolerable gains)   in the frequency range of interest must be shown, as illustrated in Figure 2, when the setup is excited in the three axes and at different locations of the top plate of the FMP .    For example,  the first generation 1 -kHz FMP is shown in Figure 3. The syste m uses three Kistler type  9067 tri -axial load cells , nine Kistler 5010B0 charge amplifiers , National Instruments type PCI -6033E data  acquisition card,  and utilizes  LabVIEW ’s interface software to acquire data at 5000 samples/sec . The  system r esolves the th ree orthogonal forces from each of the three tri-axial load cells to the three  resultant forces  in the X , Y and Z axes  and three moments M X, M Y, and MZ. Jitter forces and moments are  measured from 1  Hz to 1  kHz with a resolution of 0.5 Hz. Upon acquisition,  fast Fourier transforms are  performed on the data to provide frequency domain equivalent data through a  software interface.
433 EFT testing generates large amount of data over short time spans . In addition to data acquisition and  management, the Ball-developed Dynamic Measurement and Analysis  software platform provides  realtime fast Fourier transforms  and power spectral densities , and sliding window analysis . Multiple  dynamometers can be used within a single setup with r eal-time viewing of time -domain and limited  frequency domain. A configuration file allows for quick addition of new dynamometers and sensors such  as encoders and ac celerometers . Finally , both real time and frequency data can be easily imported into  Excel or MATLAB for processing with a suite of scripts,  allowing analysis and automatic data plotting.  

Background Noise Measurement  

When characterizing EFT from mechanis ms, identification of the magnitude and spectral properties of the  noise floor at different times  of day  (and sometimes at different physical locations) is performed.  The  noise floor is lower during the late evening/early morning time, and when testing is performed in  the  massive reinforced concrete t est pit facility  which is part of a large t esting facility  at BATC . The noise floor  magnitude depends on the type of electronics  used in the FMP  design, its  size, and whether an EFT table  is used for support . Typical background noise is less than 1E-4 N as illustrated in Figure 4 . The bulk of  the noise is of environmental  nature. At times, s hutting down equipment in the vicinity of the test may be  required,  and f acilities in upper floors or nearby urban roads ar e usually nois ier.  

Figure 4.  Typical background noise characterization processed by a dynamometer  

When noise gets in the way of measurements at a particular frequenc y range, s pecial filtering is used to  extract the necessary signal of interest . Signal -to-noise ratio measurement s significantly  improved   through a development program  in which a new set of quality electronics are integrated.  Reference [2]  presents an example where filtering using a 10- Hz low bandpass was required to achieve balancing  of a  rotating mechanism . An example of dynamometer noise floor measurement for the Y -axis is shown in  Figure 5. In this case, t he maximum noise of 0.00175 lbf  (7.8 mN) was measured and was less than the  derived 0.004- lbf (17.8- mN) limit needed for accurat e measurements  of the static  and dynamic  imbalances of the GMI instrument.
435 speaker force transducer and the measurement from the setup are the sam e in different orientations. In  particular, this test is important in the calibration of the meas ured three moments.  

Third, the calibration program evaluates data collected from auxiliary tests with rotating payloads  with  known, off-axis masses which are preci sely located on a rotating disk  mounted to the FMP . 

These tests assess the performance of the setup in measuring certain loads that result from simultaneous  measurements from all load cells , over a good range of amplitudes.  Such tests can also be used for  trouble shooting and mitigation prior to handling critical hardware.    When the unit under test  has large moving surface areas , jitter measurements may require testing in near  vacuum environment to ensure that air drag is not affecting the inherent jitter measurements.  BATC has  developed the necessary tooling to ensure that tests are conducted under such condition  in vacuum  chambers. Of course, such environments require a good portion of the setup to be vacuum compatible.      Examples of Jitter Mitigation and Isolation  

Mechanical Cryogenic Refrigeration   Traditionally, high- precision space infrared instruments have been cooled using expendable cryostats   which are inconvenient in the sense that they are not only large and heavy;  they are also short -lived, and  only capable of cooling small detectors . Cryostats are however highly reliab le, because they  are passive  and have no exported jitter to impact sensitive optics and detectors . 

Figure 6.  Early expendable cryostats (left) and cryocoolers (right)   In the past two decades,  mechanical cryogenic refrigerator s (cryocooler s), shown in F igure s 6-7, saw  their reliability improve d dramatically . They can support much larger (10- 100X) detectors and sustain  missions of  much longer dur ations (2- 5X). But, cryocoolers have moving mechanisms that can produce  significant jitter . Until recently, these levels of jitter have been unacceptable for the highest precision  space instruments .
436  

Figure 7.  Bode plots of the BATC cryocooler  (left) and cryocooler with soft mount (right)  

BATC addressed e xported force and t orque ( EFT) mitigation of cryocoolers  on the bas is of simple  passive concept s using mature, flight-proven elements with performance verification using  a high-fidelity  EFT test bed. Effectively, low resonant soft mounts of about 10 Hz are introduced to (a) maximize  attenuation at cooler operating  frequenc ies greater than 67 Hz , and (b) minimize cross talk and moments   (see Figure 2). As a result , the cooler EFT is attenuated by more than a factor of 40, from 400 mN to  about 10 mN.  The soft mount isolators use flight -proven heritage. The cooler itself has good flight  heritage with internal vibration control already <400 mN . The EFT mitigation program improved the  performance of BATC’s line of cryocoolers dramatically as illustrated in Figure 8.  

Figure 8.  Isolation performance  of BATC’s cryocoolers    EFT control is achieved at several levels. First , at the system level BATC transitioned from a single cooler  mechanism to a mechanism pair. This has brought down the imparted loads  by allow ing for the design of  effective actuation control architecture with reaction cancellation over the frequency range of interest.  In  addition,  the design of a soft mount system  has provided additional reduction of the exported loads.  

Isolation in Reaction wheels   Jitter due to reaction wheel vibration is isolated through constrained- layer flexures. The flexures were  developed during a BATC  R&D program in which three competing designs were proposed. The final Bode Diagram Frequency  (Hz)10-110010110210310-410-2100102From: NGcoolerFlexgoodcableslinksISoFEM/C2 (pt. 1)  To: Out(1)Magnitude (abs)    X Y Z
437 design retained for testing was produced in collaboration with CSA Engineering and was built to flight  hardware standards using materials with proven flight herit age.      The jitter isolation mounts  are an assembly of soft flexures that attach between a reaction wheel and the  spacecraft interface,  providing low frequency isolation in the six degrees of freedom, yet they deliver  relatively high second order spring surge modes. Thus, by design, jitter isolation mounts  have their first  six modes below 10 Hz and all subsequent modes above 100 Hz.      The final jitter isolation m ount design , shown in Figure 9, is a hexapod of six struts configured in a Stewart  platform. Each strut is made of two centrally connected rings of 10- mil (.025- mm) thick 3M ISD142R  viscoelastic layer constrained between two 9-mil (.23-mm) thick and 0.5- in (1.3-cm) wide 300- series  stain less steel sheets.  

Figure 9.  BATC Robi Wheel on j itter isolation mount     

Figure 10.  BATC Robi Wheel on j itter isolation mount and zero -g air lift (left) and typical   requirement program verification (right).        

   Figure 2.4: X-axis disturbance torqueswheel speeds in RPM.110100100010000 1 10 100 1000 Disturbance Frequency (Hz)Disturbance Amplitude (mN-cm)60 309.333 558.667 808 1057.333 1306.667 1556 1805.333 2054.667 2304 2553.333 2802.667 Original Reqt Line Contractual Reqt Line Prelim. Contract
438 Conclusion  

Ball Aerospace & Technologies Corporation made substantial capital investment  to develop  good control  of exported forces and torques from space mechanisms . And over the past decade, t here has been a  continuous improvement of  the hardware and analysis tools  used to develop advanced verification  capabilities.  

In order to meet a wide range of jitter requirements  from multiple programs, BATC elected to have the  capability to rapidly design custom FMPs for each application by combining modular hardware . This  choice prompted the development of a facility with tool kits of multiple input channels , sensors  of different   capacity and sensitivity , high -performance filters, shakers of different sizes , and data acquisition systems .  The EFT facility at BATC includes  soft tables for th e elimination of environmental disturbances . In the  pursuit of quietness, testing has been carried in several environments, such as a massive  reinforced  concrete pit and vacuum chamber s. Recently, t he EFT facility has successfully characterized BATC’s line  of cryocoolers, shutter mechanisms and performed static and dynamic balancing of rotating instruments ,  to name a few.    FMPs have the advantage of providing resultant jitter forces and moments imparted by a mechanism either directly at its mounting interface or at a higher assembly interface, depending on what is tested. Other methods of jitter verification, such as those based on the recover y accelerations or motions, from  accelerometers or transducers would have the disadvantage of being indirect methods and are therefore  less reliable. The main disadvantage of FMPs is in the introduction of additional spectral content from the measuring device itself. However, s uch addition is monitored and separation from the frequency band of  interest is one of t he elements of  the design process. FMPs may be considered complex to develop.   However the return on investment is quite important, especially when high performance is required from precision mechanisms and instruments.  

References  

1. Force Limited Vibration Testing, NASA -HDBK -7004C, 2012    2. Ayari, L., Kubitschek, M., Ashton, G., Johnston, S., Debevec, D., Newel, D. and P ellicciotti, J. “ GMI  Instrument Spin Balance Method, Optimization, Calibration, and Test ”, Proceedings of the 42 nd  Aerospace Mechanisms Symposium, NASA Goddard Space Flight Center, May 14- 16.  

3. Marquardt, E.D., Glaister, G., Marquardt, J.S., Raab, J. and Durand, D., “Testing Results for Low   Exported Force and Torque Cryocooler Mounts,” Cryocoolers 17, ICC Press, Boulder, CO (2013),    4. Ayari, L. “ Hybrid Testing & Simulation-  The Next Step in Verification of Mechanical Requirements in the  Aerospace Industry ,” Hybrid Simulation Theory, Implementation and Applications, Victor Saouma,  Mettupalayam Sivaselva Editors, 2008.
440 developed. It combines Keyence sensors [ 2] and Huber thermostat [ 7] with  Almatech software and  hardware.   

Figure  1.  Slit Change Mechanism prototype   

Figure  2.  Metrology system  

Key features    The metrology system has the following key features.    ● 6 degrees- of-freedom    Simultaneous measurement of specimen's  absolute  position and attitude in 3D .  ● Clean environment   The environment around the specimen is clean and hermetically sealed .   It is purged with high purity nitrogen, providing an environment better than ISO 5 (class 100) .   ● Temperature control    Mechanical interface temperature is controlled by external thermostat  [7] within the range from -40°C  to +200°C with stability of 0.01 °C. Change of the temperature does not  affect spatial measurement  accuracy  as the measurement devices are thermally isolated from the observed specimen.   ● Contactless measurement    The measurement is purely optical and will not damage the surface of the test subject . In addition, no  measurement bias is introduced from any contact force.

● System self -calibration     A self -calibration methodology was developed. The s elf-calibration enables the metrology system to  deduce positions and attitudes of its own sensors without using any additional measuring equipment .
441 The self -calibration  allows excluding errors caused by  the assembly inaccuracies and the thermal  deformations of the metrology system structure.   ● Sensor combination  (fusion ) method  :   Thanks to an advanced algorithm combining the information from individual sensors, the final accuracy   of the system is  higher than the accuracy of  its components . 

Object under O bservation  

The specific object tracked by the metrology system is the SCM end effector  which is  called Carrier . It is a  small titanium part  (40⨯11⨯7 mm; 2.4 g)  which carries a cartridge with silicon slits. The Carrier  moves  to  change the slit aligned with the sunlight beam . The Carrier  is shown in Figure  3. The yellow -marked  surfaces are used by the metrology system to track the position and the attitude of the Carrier . Carrier is  coated with a black mat coating.   

Figure  3.  SCM end -effector  

Hardware layout  

The metrology system  hardware is shown in Figure 6, a cut view is shown in Figure  5, and the  corresponding diagram is shown in Figure 4.  As shown in Figure 4, t he whole setup is located in a clean   room  ⑩. The test subject  ⑨ is installed inside of the heat exchanger  ⑧. The h eat exchanger  is a copper  structure with observation openings and a channel for the heat transfer fluid. Fluid circulates between the  heat exchanger and the external thermostat  ⑦. The Heat exchanger is installed inside of the hermetic  aluminium chamber  ② with sealed glass windows. The chamber is purged through the dedicated valve  with high purity nitrogen ⑤ to maintain a low humidity level as well as  a cleanliness level better than  ISO  5. 2D distance sensors ①  are installed on micrometer  positioning stages outside the chamber. They  observe the test subject through glass  windows . Sensor  heads  and the chamber are supported by the  same structure ⑥ which is made of stainless steel and polyvinylidene difluoride (PVDF ). Sensor  heads   are connected to the acquisition devices ③  which , in turn,  are connected to the computer ④. 

For the particular SCM that is sensitive to microvibration, the system was inst alled on the optical table  with air pneumatic bearings  to reduce microvibrations. Mechanical stops  protect the test subject and  sensors from unintentional contact with other parts of the system during the assembly.  

Sensors have a limited operational temperature range, therefore sensor support structures are made of  PVDF with multiple holes for a better thermal decoupling from the heat exchanger. The temperature at the interface of the test subject is monitored by thermocouples.
443   Figure  6.  Metrology system hardware  

Measuring principl e 

Specimen position and attitude in 3D are calculated from  the raw data acquired by three  2D distance sensors [ 2] which are aligned as shown in  Figure 7. Each 2D distance sensor captures a  cross- section of the Carrier as shown in Figure 8.  The combination of the 3 cross -sections is processed  by a software developed by Almatech to provide an accur ate position and attitude.
444  

Figure 7.  Position and attitude of the sensors  

Figure 8.  Test subject sections observed by the sensors  

The algorithm contains the following major  steps :   1. Acquisition of the specimen  cross- sections  (shown in Figure 8) from the 2D laser distance s ensors.  Cross -sections are represented by the arrays  of points;   2. Fitting the polyline s to the acquired points using linear segmented regression. Calculation of p olyline  vertices coordinates  and evaluation and their uncertainties ;  3. Calculation of  specimen position and attitude by minimizing error between measured vortices and  specimen model . 

The 1st step (acquisition of raw measured points) is done using application programming interface   provided by the sensor manufacturer. Raw measured points are shown in Figure 9 as the blue dots.  

In step 2, the software calculates cross -sections vertices coordinates from the measured points  coordinates. Cross -section best -fit profile is shown in Figure 9 as a blue polyline. Initial set of points is
445 split into subsets so that each subset contains points of a single line. The boundaries between subsets  are found by  minimization of the sum of  quadratic  mean errors of best -fit lines.  

Vertices coordinates are not the only output of the 2nd step. Uncertainty is also automatically estimated  for each vertex in order to reach a higher accuracy during sensor fusion. Sensor  fusion is a process of  combining sensor  data such that resulting information has less uncertainty than would be possible when  these sources were used individually.  

Figure 9.  Real and recovered profiles    Uncertainty of each vertex coordinates depends on multiple parameters, such as size and arrangement of lines in the field of view. The equation  to estimat e the vertices  coordinates uncertainty is derived from the  following set of equations:  

yLi(x)=ki∙x+bi (1)  yL1(xV)=yL2(xV)=yV (2)  ki=cov� xPi ,yPi � var� xPi � (3)  bi=mean� yPi �−kL∙mean� xPi � (4)
446 syPi=�1 ni−2∙��yPij−yLi(xPij)�2ni j=1 (5)  xPij=�j−1 2+Θ�∙sign (i)∙∆ (6)  sF(a1 , a2 , …)=�� sa1∙∂F ∂a1 �2 +� sa2∙∂F ∂a2 �2 +⋯ (7) 

where  x ,y – Coordinates in the sensor frame    i – Index of the line. The vertex is formed by t wo lines (1 and 2).    j – Index of the measured point.  Each line may contain deferent number of points.    yLi(x) – Best-fit function for the line i.   ki – Estimator of the slope coefficient for the line i. It is a trigonometric tangent of  the angle between the  best-fit line i and the X axis .   bi – Estimator of the intercept coefficient for the line i. It characterizes the shift of  the best-fit line i along the Y axis .   xV ,yV – Coordinates of the vertex  which is formed by intersection of two lines .   cov(…) – Covariance.    var(…)  – Variance.    mean(…)  – Average.    xP ,yP – Coordinates of measured points.    ni – Quantity of measured points in the line i.   syPi – Estimate of q uadratic mean  distance  (along Y axis)  between  measured points  and the  best-fit line i.   ∆ – Resolution of the sensor  head . This value is  the distance between neighbour  measured points along X axis.    Θ – Coefficient  which characterizes the distance between the vertex and  the nearest  measured points.  Its value  lays in the range  between  -0.5 and +0.5.    sF(a1 , a2 , …) – sample standard uncertainty  of some function F with the arguments a 1, a2, …  

Equations 1, 3, and 4 represent a linear regression as per [ 9]. Regression gives a better result than  orthogonal Deming regression due to the specific internal architecture of the sensors. Equation 7  is a  well-known variance formula for uncertainty propagation from [ 10]. Vertex coordinates are derived from  equations 1 and 2 as: 

 xV=b2−b1 k1−k2     ;    yV=k1b2−k2b1 k1−k2 (8)