ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
447 Equation 7 is applied to equations 3 , 4 and 8 to calculate uncertainties of the vertex coordinates. For  that,  the coordinate system origin is aligned with the vertex. Coefficient Θ of the equation 6 is assumed equal  to 0.5 which is the worst case estimate. The standard uncertainty of the vertex  coordinates is:  

sxV=2∙��syP1�2 η1+�syP2�2 η2 (k1−k2)2    ;   syV=2∙��syP1�2 η1∙k22+�syP2�2 η2∙k12 (k1−k2)2 (9) 

Where η are coefficients which characterize quantity of points in each line  as:  

η1=ni∙(ni−1) ni+1 2 (10)  Once the positions of vert ices are calculated, the m etrology system software proceeds to the 3rd step  which search es for the corresponding position and attitude  of the Carrier . This is done by solving the  following system of equations . The system is solved using a variation of Nelder –Mead method [11]. 

⎩⎪⎪⎪⎨⎪⎪⎪⎧       

                pvijksi=𝒂𝒂 siI−1 ∙�𝒂𝒂 tI∙pvijkt∙𝒂𝒂 tI−1 +ptI−psiI�∙𝒂𝒂 siI (11) Conversion of vertices coordinates  from Carrier frame to sensor frame.   See Figure 11.  peijsi=pvij0si+�pvij1si−pvij0si�∙pvij0si∙z (pvij0si−pvij1si)∙z (12) Intersection point of the line  (Carrier  edge) and the xy -plane (laser beam  of the sensor). See Figure 10.   �  ��𝐌𝐌eij ∙�peijsi−p�eijsi��2nesi−1 j=0ns−1 i=0=f→0 (13) Sum of weighted distances between  points (measured and assumed ) of  intersection.  

where  ● ─ scalar values     ● ─ 3D vectors    ● ─ 3⨯3 matrixes    ● ─ quaternions    pvijksi ─ assumed position of the Carrier  vertex ijk  in the coordinate system of the sensor i    pvijkt ─ assumed position of the Carrier  vertex ijk  in the coordinate system of the Carrier     𝒂𝒂 siI ─ assumed attitude of the sensor i relative  to the SCM interface    psiI ─ assumed position of the sensor i relative  to the SCM interface    𝒂𝒂 tI ─ assumed attitude of the Carrier relative to the SCM interface    ptI ─ assumed position of the Carrier relative  to the SCM interface    peijsi ─ assumed position of the point of intersection between flat laser beam of the sensor  i  and the Carrier edge  ij which connects vert ices ij0 and ij1 in the sensor  i coordinate
448 system    p�eijsi ─ measured position of the intersection point  ij defined above    z ─ binomial unit vector ( 0;0;1)T of the sensor coordinate system basis    ns ─ number of sensors in the metrology system    nesi ─ number of  the Carrier edges observed by the sensor  i    𝐌𝐌eij  ─ scale matrix  which contains  the uncertainty  of measured  intersection point  ij   𝐌𝐌eij = ⎣⎢⎢⎢⎢⎡  �seijx�−1 0 0 0  �seijy�−1 0

0  0  0 ⎦⎥⎥⎥⎥⎤  seijx ─ uncertainty  of X-coordinate  of the  intersection point ij   seijy ─ uncertainty of Y -coordinate  of the  intersection point ij       f ─ objective function  which  shall be minimized. It characterizes the deviation  of the  assumed intersection points  from the measured intersection points  

Figure 10.  Intersection point of the Carrier  edge and the laser beam of the sensor   

Figure 11.  Coordinate systems (frames) .   Red is a sensor frame.  Blue is a Carrier frame .   Green is a SCM interface frame . 

Self-Calibration  

To reach high accurate measurements, both Carrier 's geometry and positions of the sensors  shall be  known. Carrier 's geometry is measured before test using the coordinate measurement machine. Positions  and attitudes of the sensors are calculated during a so-called self-calibration process.  The sensors  measure a calibration target  (shown in  Figure 12) which has  known geometry  and position in SCM  interface frame. The geometry of the calibration target was optimized to determine the position and
449 attitude of each sensor  using a single cross -section which is captured by the same sensor . Cross - sections observed by the three different  sensors  are shown in Figure 13. 

Figure  12.  Calibration target    

Figure  13.  Calibration target sections observed by sensors  

The calibration target is made out  of Invar  to minimize  thermal expansion effects.  This allow s accurate  measurement  over a specific temperature range.    Position and attitude of each sensor is deduced several times  for different temperature points. This  approach allows minimizing the  errors caused by the thermal deformation of the metrology system  structure. Self-calibration also minimizes  the bias caused by the deflection in the glass windows.  Calibration target sections , as they appear in acquisition softwar e interface written by Al matech,  are  shown in Figure 14 (refer to Figure 13 for sensor positions).  

Figure  14.  Calibration target sections as they appear in the acquisition software interface
450 Results  

Multiple real-life tests and software simulations were performed to determine the final accuracy of the  metrology system  with a high level of confidence.  The tests were the following:  

• Test of self -calibration accuracy (sensors positions self -determination accuracy);   • Test of inaccuracy caused by remounting of test subject and calibration target;   • Test of sensors accuracy with the representative surface optical properties;  • Test of sensors accuracy with the representative geometry.  

The estimated result  accuracy of the system  is shown in Table 1.  

Table 1. Measurement uncertainty of the metrology  system  

Parameter  Translation [μm] Rotation [arcsecond]   X Y Z X Y Z  Repeatability  00.7 00.4 02.3 11 020 014  Absolute coordinate s’ accuracy  14.4 23.3 52.4 68 178 570 

Lessons learned  

For accurate sensor fusion, it is important to take into account that the measurement uncertainty is  different for each measur ement . Measurement uncertainty of the vertex coordinates depends on multiple  parameters, such as size and arrangement of lines in the field of view. The values specified in the sensor datasheet are deduced by the manufacturer for a very particular test case, therefore they cannot be considered as an accurate estimate. For proper evaluation of the vertices  coordinates’  uncertainty,  Almatech derived the equation 9 and performed multiple tests.    It is also important to take into account that the accuracy and reliability of  laser distance sensors depends  strongly on the optical properties of observed surfac e. For better and consistent performance, the surface  shall be mat (i.e. , reflection shall be dif fuse). Several surface treatments of nickel -iron alloy were tested  (see Figure 16). Micro -ball shot -peening was selected because it showed the best combination of high  performance and low impact on specimen’s geometry . 

Figure  15.  Surface treatment samples  From right to left  : 

1. M :  Shot peening + Passivation   2. M+Nc :   Shot pe ening + Chemical nickel plating   3. Nc :  Chemical nickel plating   4. Ngm :  Mat galvanic nickel pla ting  5. no label :  Passivation only
451 Outlook  

The metrology system will be used at each stage of Slit Change Mechanism test sequence to monitor possible changes of its accuracy. The accuracy checks will be performed after the SCM assembly, the  vibration tests, the shock test, the thermal vacuum tests and the life- cycling. All tests which require  actuation of SCM will also be performed in the chamber of the metrology system in order to prevent SCM bearings coating from oxidation.  

Conclusion  

A unique metrology system  (hardware and software)  for simultaneous precise contactless  measurements  of 6 degrees -of-freedom of the Solar Orbiter Slit Change Mechanism Carrier  is implemented. It features  high accuracy, cleanliness, and temperature control.  Tests  and simulations show that the measurement  accuracy of an object absolute position is of 20 micron in in- plane measurement (XY) and about   50 micron out of plane  (Z). The typical absolute attitude is determined wi th an accuracy better than   3 arcmin in rotation around X and Y and better than 10 arcmin in Z. The metrology system is able to determine relative position and movement with an accuracy one order of magnitude lower than the absolute accuracy. Typical relat ive displacement measurement accuracies are better than 1 micron in X  and Y and about 2 micron in Z. Finally, the relative rotation can be measured with accuracy better than   20 arcsec in any direction.  

Acknowledgements  

To Keyence (Switzerland and Belgium) for support in accessing the available sensors compatible to our  surface treatment requirements.
452 References  

1. Paciotti G., Humphries M., Rottmeier F.  and Blecha L. "Development and preliminary testing of a  high precision long stroke Slit Change Mechanism for the SPICE instrument ." Proceedings of the  42nd Aerospace Mechanisms Symposium, NASA Goddard Space Flight Center , (May 2014) ,   pp. 31-44.  2. Technical specification of Keyence 2D distance sensors « LJ-V »  Access :  http://www.keyence.com/products/measure/laser -2d/lj-v/specs/index.jsp   [accessed 2015- 09-27]  3. Technical specifications  of Handyscan 3D handheld 3D Scanner  [Online]   Access :  http://www.creaform3d.com/en/metrology -solutions/products/portable- 3d-scanner/   technical -specifications -handyscan- 3d  [accessed  2015- 08-30]  4. Technical specification of Keyence 3D laser scanning confocal microscope VK -X [Online]   Access :  http://www.keyence.com/products/microscope/laser -microscope/   vk-x100_x200/specs/index.jsp   [accessed 2015- 08-30]  5. Description of Lyncée T ec reflection digital holographic microscope [Online]   Access :  http://www.lynceetec.com/reflection- dhm/#1   [accessed 2015- 09-27]  6. Technical specification of Nikon X-ray inspection system MCT225 [Online]   Access :  http://www.nikonmetrology.com/en_EU/Products/X -ray-and-CT-Inspection/Metrology -CT/  MCT225- for-Metrology -CT-Absolute- accuracy -for-inside -geometry/(specifications)   [accessed 2015- 08-30]  7. Description of Huber temperature control system  « Petite Fleur  » [Online]   Access :  http://www.huber -online.com/en/product_listing.aspx?group=1.01   [accessed 201 6-01-20]  8. Description of Acktar coating « Fractal Black  » [Online]   Access :  http://www.acktar.com/category/FractalBlack   [accessed 201 6-01-20]  9. Kenney J.F. and Keeping E.S. "Linear Regression and Correlation." Ch. 15 in Mathematics of  Statistics, Pt. 1, 3rd edition,  Princeton, New Jersey,  (1962) , pp. 252– 285.  10. Ku H. H. "Notes on the use of propagation of error formulas" . Journal of Research of the National  Bureau of Standards , Vol.  70C, No 4,  (October 1966) , pp. 263-273.  11. Nelder J .A., Mead R. "A simplex method for function minimization. " Computer Journal 7, (1965) ,   pp. 308– 313.
453 Development and Testing of a Bi -Stable Actuator based on a High Transition  Temperature Shape Memory Alloy  

Gabriel Paciott i*, Jacques -Eric Bidaux**, Hervé Girard**, Fabrice Rottmeier * and Luc Blecha* 

Abstract  

Pyrovalves , i.e., valves actuated by a pyrotechnical device,  are very often used in space propulsion systems  for their fast response, high reliability, low mass and low cost. However , they are hazardous and single use  items . Their operation induces shocks and can generate contaminants . If a slower actuation is required or  possible,  shape memory -based actuators avoid the generation of shocks and contaminants while being  fully resettable and non- hazardous devices.  

The goal of this project was to develop a bi -stable S hape Memory Alloy (S MA) actuator for a specific Slow  Acting Latch Valve with long life capability.  The benefits of this actuator makes it interesting not only for  valve actuation but also for any device that has to be actuated in a smooth and reliable way.     This paper presents the development of a bi -stable actuator based on high temperature shape memory  alloys.  

Introduction  

Shape Memory Alloys undergo a phase transformation upon cooling from high temperature austenitic phase to a low temperature martensitic phase. This phase transformation is the basis for the unique properties of these alloys. At room temperature, t he SMA can be readily deformed (l ow yield strength).  When heated above the reverse transformation temperature A f, the alloy reverts to austenite and recovers  its previ ous shape. This property is known as the shape memory  effect . With proper selection of SMA  materials and production processes, the transition temperatures can be tailored to the engineering needs .  

Figure 1.  Shape memory effect  principle    The team designed, manufactured and tested an actuator based on a high- temperature shape memory  alloy. The SMA actuator main features are:   • High reliability   • Smooth- acting   • Resettable   • Light and compact   • High temperature SMA alloy (above 120°C)   • Withstands  launch loads as high as 28.3 g RMS  • Made of space- compliant  materials                                                     * Almatech, EPFL, Lausanne, Switzerland   ** University of Applied Sciences and Arts Western Switzerland, Sion, Switzerland 

Proceedings of the 43nd Aerospace Mechanisms Symposium, NASA Ames Research Center , May 4 -6, 2016
454 The SMA actuator  developed by Almatech is based on the following operating principle:  electric current is  used to heat up multiple  SMA wires (in a parallel configuration) changing their crystalline structure in such   a way  as to shorten them and actuate the integrated latching/de- latching mechanism. Thanks to this bistable custom -designed latching device, no power is needed to maintain the actuator in one or the other  stabl e positions .  

The overall  dimensions of the developed actuator are shown in Figure 2.  

Figure 2.  Overall dimensions of the Actuator  

Main Requirements  

Table 1 presents the main requirement s that drove the design of the actuator . 

Table 1.  Main design requirements   Characteristic  Value   Mass :  < 200g   Overall max dimensions :  100  x 60  x 60 mm3   Lifetime  (with ECSS factors)  : ≥1000  cycles   Power consumption  (DC)  : <50 W (28V)  Output force:  165 N  Latching stroke : < 1.7 mm   Total stroke  > 2.2 mm   Actuation time (slow actuation) : 5s < t <60 s  Max n on-operating temperature  (Qual) : -10°C / 120°C  Max operating temperature (Qual):  -5°C / 100°C  Launch vibration load  : 28.3 gRMS  Other feature  bi-stable (stable in  both open and  closed positions   with no power supply)  

Main Challenges  

Nickel- Titanium (NiTi) alloys are the most commonly used material s for their shape memory effect. They  are off -the-shelf products and relatively low cost  due to their extensive use in the biomedical and general  industrial fields . While their maximum  transition temperatures  (Ms, Mf, As and Af) are well adapted to these  applications, they are all under  100°C , which limits considerably their use in space mechanisms design.  In  order to widen the application range of SMAs in s pace mechanisms,  Almatech has initiated , in collaboration  with the University of Applied Sciences  of Sion, Switzerland , a new development based on another shape  memory alloy, CuAlX. CuAl -based material can feature, with the adequate composition and treatments,
456 On the moving end, an electrical crimp makes the electrical connection (see Figure 4) between the heating  system lead and the SMA  wire, while the opposite end (the fixed end) is directly connected to the electric  power supply. The heating system lead located on the fixed end is connected to the other pole of the  electrical supply . 

Figure 4.  Electrical interface :  (A) Flying leads after heating system installation     (B) Connection from the fixed side  

The thermal interfaces of the SMA wire system plays an important role in the performance of the full system.   Although radiation is not negligible for space conditions, preliminary tests  first focused on the conductive  interface design . The initial SMA per formance tests showed the strong impact of the conductive interfaces  on the overall wire thermal behavior. It was observed that the conductive thermal flux significantly lowers  the end of the wire temperature (see Figure 5). This gradient induced a significant loss of the net stroke of  the sample by limiting the extent  of the shape memory effect .  

Figure 5.  Temperature losses in the mechanical fixation    To enhance the thermal uniformity, the wire ends were  thermally insulated from their supporting elements  in a second setup. This le d to the design shown in Figure 6 applied at  each end of the SMA wire. While on  one hand thermal insulation is desired to maximize the performance of the SMA wire by a uniform heating  over its full length, heat rejection is required after SMA wire heating such that it can come back to its initial state and be actuated again with a new thermal cycle. Therefore, a compromise has to be found on the  thermal insulation design that considers the trade- off between SMA wire heating efficiency and required  actuation cycling times .   Electrical crimpA BFixed end Mechanical Interface Heat lossMoving  EndMechanical Interface TemperatureFixed  End
457   Figure 6.  Thermal insulation at mechanical interface  

   Figure 7.  Wire End crimped to the SMA wire sample  

Stroke Control   

The lifetime performance of a SMA being limited by its exposure to over stroke, overstress and overheating  conditions, the powering of the SMA wires needed to be controlled to meet the required lifetime performance of 1000 cycles . In order to do so, an electrical switch has been integrated in the design to cut - off the powering of the SMA wires as soon as the system is latched and a mechanical end- stop has been  integrated to guaranty a repeatable rest position after cooling down of all SMA wires.    The switch is integrated on the backside of the actuator. A  switch lever is pushed down by a  Spring Blade  as illustrated in Figure 8. The switch is released once the Pusher rod is in latched position .  

Figure 8.  Switch actuating system  

When the SMA Wires are activated, the Pusher rod travels  forward. Once the adjustable nut supported by  the threaded rod touches the Spring Blade, it shuts off the electrical supply and heating of the SMA wires .  Mechanical Interface Thermal Insulation Threaded Rod Adjustable Nut (self-locking) Sealed SwitchSpring BladePusher
458   Figure 9.  Fully assembled SMA Actuator  

SMA Actuator Test Sequence    The test campaign consisted of the following test sequence:   a. Cycling tests at SMA wire assembly level   b. Cycling tests at mechanism level   c. Mechanism v ibration test   The first test aims to verify the correct actuation of a wire alone before integration into the actuator. It allows to ensure  its capability to actuate under the required load and over the required number of cycles. Full  performance test results of the developed Engineering Model were prioritized over the verification of its structural resistance to launch loads, such that these tests were performed at the end of the campaign and  followed by final functional tests.  The corresponding test results are presented hereafter.  

SMA Wire  Cycling Test Results  

The goal of the life  test was to demonstrate the maxim um number of actuation cycles that can be performed  by an equipped SMA wire. The pass/fail criteria considered was the successful achievement of  more than   1000 actuation cycles with 2.7- mm stroke under 70- MPa load.    The schematic drawing of the test jig is shown in  Figure 10. The equipped wire samples were  mounted to  the fixtures of the test jig and a weight was attached to the lower fixture. The t est setup is such that t he  initial position of the weight can be either in contact with the platform ( load relief ) or hanging on the SMA  wire (free load). The SMA wire is actuated using the developed heating system using a constant current .  The wire shrinks  when actuated and lifts the weight  in a loaded configuration. The displacement is  measured using an  LVDT transducer. As soon as the required displacement is achieved , the current is  switched off. The weight the n gradually returns to its initial pos ition as the wire cools down and a new cycle  is initiated . The test finishes when the predefined number of cycles are performed. The SMA wire  temperature is monitored continuously using a type K thermocouple.
459   Figure 10.  Schematic drawing of the equipped SMA wire test jig  

The tests were performed starting from two initial positions: f ree load (weight hanging) and offloaded (weight  in contact with the platform). The position of the upper fixture was adjusted using a microm etric screw.    Two tests were performed with the following load conditions :  • 40 MPa (30. 62 N) , to verify the ability of the SMA to reset  (recover the original position)   • 70 MPa (51. 12 N) , the maximum determined stress for infinite cycling  

Figure 11.  Cycling under  the load of 70 MPa  

Figure 11 shows a uniform cycling dem onstrating the adequate behavior of the wire at 70 MPa. The same  test was performed at 40 MPa demonstrating its ability to reset fully at this stress  level.
460   Figure 12.  Cycles 7646- 7657, load 70 MPa, stroke 2.7 mm, current 1.94 A  

By the end of the test,  7657 cycles were successfully performed as illustrated Figure 12 . During the cycle  7658, a fatigue failure  occurred close to the middle of the wire as shown in Figure 13.  

Figure 13.  Equipped wire after wire failure  

Actuator Cycling Test Results  

In order to study the cycli ng and ti me-dependent properties of the actuator, the following test  was  performed:   • Loading force = 96 N (reduced from the theoretical  175 N to ensure SMA cycling  survival  and  verify the heating system  over the full lifetime requirement )  • Power supply  : 1.79 A, 2 7.8 VDC, 49.8 watts   • Cooling time between cycles = 15 seconds (to ensure that the actuation time at the next cycle will  not be affected by an incomplete cooling at the previous cycle)    • Heating time limit = 15 seconds ( overheating risk )   • Standard ambient temperature and pressure conditions    The actuator survive d the required 1000 cycles and switched  its state (latched or released) automatically  at each cycle.  The cycling test of the actuator was fully  successful as illustrated in Fi gures  14 and 15   showing the four initial cycles and the last four cycles .
463   Figure 18.  Random vibration spectrum in the axial direction  

Figure 19.  Random vibration spectrum in the radial  direction  

The SMA actuator successfully sustained both axial and transvers e random vibrational  loads  with overall  acceleration of 28.3 g RMS and duration of 3 minutes each. No changes  in the resonance search results  were observed before and after the random loads application showing that no structural failures have