ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
175  Figure 8.  Dependence of number of strokes  and time of imbed from depth for five power  settings.   EMOLE needed more strokes  on higher power  levels to reach t he next ten centimeters  because the bottom volumes of the regolith  were much more compressed.     Figure 6.  Dependence of time imbedded from  depth in Syar regolith analogue.    Figure 7.  Dependence of number of strokes  from depth in Syar regolith analogue. Numbers  of strokes are presented for 10- cm depth  sections and only first one is for 15 cm.  

Environmental tests   During  the tests conducted in a vacuum chamber, EMOLE was run after degassing (p=0. 075 mbar) for  about 5 strokes each for all 5 power settings. No problem with launch or any  unusual behavior  occurred.  After gassing  the vacuum chamber, the test was repeated again without  any problems.  

Vibration tests   The last and the most crucial test concerned durability in regards to vibrations. Thanks to the fact that  the  propulsion is axially symmetric, t ests were performed along two axis: one parallel to the axial  symmetric  axis and the second one perpendicular  to it. In these tests the counter -mass and the hammer were  locked. One additional test was performed in which the hammer and the counter -mass were held by an  external, permanent magnet. During and after vibration tests with locked counter -mass no problems or  difficulties were observed. Afterwards, the drive  was run without any problems on all power settings what  proves its high resistance against ov erloads. The preliminary vibration tests with unlocked the counter - mass and the hammer that were held only by  magnetic field generated by permanent magnet, showing   that this kind of solution is able to prevent the driving sections against damage during vibrations that are  generated by a starting rocket.
176 Conclusions  

A multi- sectioning, reconfigurable electromagnetic hammering propulsion is the first such type of drive to  be used  in mole penetrator. The main structural novelty, i.e. , use of several electromagnets arranged in  stock as a direct hammer propulsion, gave twofold improvements. First  of all, owing to the fact that  the  electromagnets do not need any drive transmissions and they do not have any rotating parts (e.g., a  DC  motor ), the whole instrument became much simpler and more reliable. Secondly, the drive has the ability  to adjust hit energy during operation, which can contribute to saving energy and to protection of the  scientific instruments from damage. Furthermore, to provide an additional mode in which the typical  operation is superimposed with a high fr equency and low energy mode, a new electronic control was  developed.  The simplicity of the direct  drive solution, its relevance to the  previous flight models of MUPUS (Rosetta), CHOMIK ( Phobos -Grunt) and  mole penetrator “KRET” , along with the  experience of CBK PAN,  give a path for  fast development to a  high TRL i n a short  time.    EMOLE is a low -speed penetrator  capable of mobility within the regolith subsurface and is the first mole- type  penetrator that employs an electromagnetic linear drive system.  Lightweight  and compact EMOLE either as a whole device or only i ts new electromagnetic  direct drive, may become flexible solution for space exploration missions  providing a wide range of the possible applications, e.g.,:  ● carrying sensors (e.g. , thermal,  miniature spectrometers, cameras) underneath the granular matter of a celestial body   ● subsurface ground sampling   ● anchoring of la nder in microgravity  conditions   ● anchoring (better coupling with the  ground) e.g. , seismometers   ● act as a special actuator for generating  high pulse force (1000- 2500 N) 

References  

1  Grygorczuk, J. et al.: 2011. Advanced penetrators and hammering sampling devices for planetary  body exploration.  In proc. of the 11th Symposium on Advanced Space Technologies in Robotics and  Automation, ESA/ESTEC, Noordwijk, the Netherlands.   2 Grygorczuk, J. et al.: MUPUS Insertion device for the Rosetta mission. Journal of  Telecommunications and Information Technology , pp 50 -53, 1/2007   3 Wiśniewski, Ł., et al.: Pre -testing results and EMOLE’s performance.  2015.   4 Krasowski, J., et al.: 1. WP5 Electrical Design Description, ( EMOLE – progress report ), 2014.   5 Kędziora B, et al.: Report on testing the penetration of a mole and testing the operation of the mole  drive in space simulated conditions , (EMOLE – progress report ), 2015.   Table 2.  Summary of the drive  attributes.
179   

Figure 1.  Anisotropic Magneto -resistive Effect [2]  

The structure of an AMR angle sensor is comparatively simple (see Figure 2). This is one of the reasons  that the passive resistive elements are fundamentally reliable. A silicon oxide layer provides the isolation  between a silicon wafer (which only acts as a substrate for the thin- film metallic sensor – it has no  semiconducting function) and the MR layer. The MR layer consists of a nickel -iron alloy (e.g. , Permalloy).  This alloy has a high resistivity and demonstrates very low magneto- striction. The next layer comprises an   aluminium or gold layer providing the conductors within the sensor as well as the bond contacts. A   passivation layer provides protection against the environment in which the sensor chip is applied. Modern  production processes in the wafer production, as well as well -matched material pairings allow the  temperature coefficients for the output signal amplitude, the offset voltage,  and the res istance to be  reduced to a minimum. This allows the MR sensor chips to be used in applications at both low and high  temperature without significant changes in performance.  

To reduce the influences of temperature on the sensor chip even further the sensor structure typically features four resistances connected in a Wheatstone bridge arrangement.  

Figure 2.  Structure of Sensitec’s AMR Angle Sensor [2]   In AMR angle sensors , two bridges  at an angle of 45° to one another  are interlaced in order to generate a  sine and cosine output signal as a function of angle.  This signal type is generally also known from other  angular sensor concepts, e.g. , resolvers or optical encoders.    The advantage of the MR sensors is that an unambiguous angular output can be provided even without any signal condit ioning. A pre- amplified analog output signal possesses  theoretically  infinite resolution  and could be directly fed into the controller of the application.    Howeve r, for the sake of simplicity the sine- cosine output voltage signals are typically pre- processed by  means of front end electronics to deliver digital output signals according to the typical interfaces used in industry. For industrial and terrestrial purposes , commercial amplifiers and interpolation ICs are used. For
180 high performance demands microcontrollers are implemented. However, it is also possible to use passive  discrete devices only to provide a digital output, yet knowing that the resolution  will be limited. Still this  makes the MR sensors ideal candidates for cost efficient position sensors in many space applications where moderate performance is required.  

Sensor Specification    In general,  MR-based sensor s possess the unique advantage that in order to comply with low or medium  performance demands  (i.e., up to 11 bit resolution) , basically no front end signal conditioning  is required  to provide the user w ith a reasonable angular signal  due to the intrinsic sine- cosine output signal. In order  to achieve discrete (hence TTL compatible) sensor output signal , only a reduced signal processing is  required.  This is desired by most potential users  and makes this concept  an ideal candidate for low to  medium performance 360° incremental encoders with a reference pulse . Such sensor can be used to  replace potentiometers in mechanisms in order to improve reliability, performance and to keep the costs at low level, or to enable closed- loop motor control for improved mechanism performance and reduced  microvibrations. Such medium performance encoder could be used for instance for:   • Antenna pointing mechanisms   • Shutter mechanisms   • Calibration mechanisms   • Reaction wheels (e.g. , as wheel speed sensors)   • Robotic exploration (e.g. , wheel position sensors, as already used in case of the Curiosity Rover [1] )   As a baseline for the design of the Magneto- Resistive Angular Sensor for Space Applications ( MRS ), a  dedicated pilot application was selected, and the technical requirements were  derived. The baseline  specification is given in Table 1.    It is worthwhile to highlig ht that the AMR and GMR sensors  developed and produced by Sensitec al low  for various sensor concepts;  hence it is also possible to design and qualify mission -specific or user - specific encoders, allowing for true power on absolute angular measurements, or high resolution and high accuracy angular measurement.  

Table 1.  MRS  Key Requirements  Specification   Requirement  Value   Angular Range  360° (no deadband)   Rotational speed  > 100 RPM   Resolution  > 10 bit  (~0.3°)   Repeatability  < 0.5° (goal: 0.1°, TBC)   Measurement type  Incremental with reference pulse   Output signal  Digital ABZ (TTL)   Power consumption  < 150 mW (TBC)   Lifetime  on ground: > 15 years, in orbit operation: > 15 years   Temperature, operational  -50°C ... +100°C   Temperature, non -operational  -60°C ... +110°C   Radiation hardness  > 250 krad   Mass  < 150 g   Mechanical I/F  End of shaft configuration:   -shaft diameter:5 mm   -outer diameter: 50 mm  -height: 40 mm  Alternative hollow shaft configuration:   - shaft diameter:30 mm  -outer diameter: 75 mm  -height: 25  mm
181 Preliminary Sensor Design  

Based on the baseline specification,  a preliminary MRS  design has been developed. In its baseline  configuration,  the encoder will be attached at one end of the shaft, e.g. , at the secondary shaft of an  actuator, to allow for closed- loop control. In this configuration, the MRS  is most compact and small, yet  provided sufficient performance (> 10 bit resolution). This concept is illustrated in Figure 3.  

The MRS  consists of a magnetic measurement scale (also referred to as pole ring) with a diameter of   45 mm and two parallel magnetic tracks. One magnet ic track has 282 magnetic poles  that are used for  the incremental position measurement. The second magnetic track has one pole pair that is used as a  reference pulse, giving precisely the 0° position. The position is measured by an AMR sensor and a GMR sensor for the reference pulse. The MRS is designed to be fully redundant. The MR sensors provide an  analog sine-cosine signal. In fact , for each pole pair two full sine- cosine periods are provided.                                   

Figure 3.  Preliminary baseline MRS design    The sensors will be housed in a dedicated LTCC package, conforming to ECSS outgassing and quality  standards. The sine cosine signals can directly be delivered to the motor controller. However, often a  discrete signal (e.g. , TTL signal) is required by the controller. In order to provide this interface, a  dedicated front end electronic board is included in the sensor (nominal and redundant), which transforms the sine- cosine signals into a TTL- compatible pulse signal (ABZ, 0 -  5V). This is achieved by a set of  comparators and operation am plifiers, which allow to deduce from the pre- amplified sine -cosine signals, a  pulsed signal (AB , view Figure 4)  with four pulses per pole, resulting in a resolution of about 0.3°. The A  and B pulses are phase shifted, allowing determination of  the rotation direction.    In the baseline configuration the PCB boards are located in parallel to the pole ring, behind the end of the shaft to minimize the envelope.    A higher resolution can be achieved if a larger measurement scale (i.e. , pole ring) is used  with the same  sensors and front end electronics. In order to reduce the costs of the final product, off -the-shelf ferrite  pole rings will be  used. The largest off -the-shelf pole rings currently available have an outer diameter of  72 mm (inner diameter 54  mm), giving roughly 0.2° resolution. This enables a hollow shaft configuration,  where the electronic board s are attached radial ly (view preli minary design in Figure 5 ).   Shaft  interface Pole ring  MR sensors   (nom. +red.)   MR sensors   (nom. +red.)  Front end  electronics   (nom. +red.)   Housing
182   Figure 4.  Signal conditioning approach         Figure 5.  Alternative  hollow sha ft configuration of MRS with 72 -mm pole ring  

Development and Qualification Approach    The ultimate objective of this  development is to develop and qualify an MR -based contactless angular  position sensor in order to achieve swift and efficient entry into  the market.    The technical requirement specification has already been consolidated  and finalized  based on a relevant  reference applicat ion. Currently , the MRS  design is further elaborated, and it is planned to build and to  test the MRS  at breadboard level  soon. Breadboard models and several tests are foreseen to validate the  measurement and signal conditioning concept. These tests include functional and performance tests of  the electronics, as well as full -scale functional and performance tests in reduced and elevated  temperature.    Ultimately , Engineering Qualification Model s of the MRS  will be built and qualifi cation tests shall be  performed in order to achieve TRL 6. The qualification tests to be performed include functional  performance tests at ambient and thermal vacuum, vibration and shock tests, electro- magnetic  compatibility and electro- static discharge tests (EMC, ESD) as well  as outgassing tests and radiation  tests.  A  B
183 Conclusion  

The baseline requirements, pilot applications, and a preliminary flight design of an MR -based contactless  angular position sensor  dedicated to space mechanisms were completed. Breadboard activities will  be  initiated to validate the concept. This will be followed by a dedicated qualification test campaign using  qualification models in late 2016 /  early 2017. It is planned to present the qualified MRS  mid 2017.  

Acknowledgements  

The authors would like to thank ESA for the kind support and technical guidance in this activity as well as  all companies and research institutes who provided valuable inputs and information to our market study  during the user consultation.  

References  

1. M.R. Johnson  et al.: “The Challenges in Applying Magnetoresistive Sensors on the Curiosity Rover”  12th MR Symposium 2013, Wetzlar   2. R. Hahn, B. Olberts: “Feasibility Study Magneto- resisitve Sensors for Space Applications –  Final  Report” MRS -HTS-RP-001, ESA Contract N o. 4000109333
185 Cu-Al-Ni Shape Memory Single Crystal Wires with   High Transformation Temperature  

Alain Hautcoeur*, Florian Fouché* and Jacques  Sicre** 

Abstract  

CN-250X  is a new material with higher performance than Nickel- Titanium S hape Memory Alloy  (SMA) . For  space mechanisms , the main disadvantage of Nickel -Titanium Shape Memory Alloy is the limited  transformation temperature. The new CN -250X Nimesis  alloy is a Cu -Al-Ni single crystal wire available in  large quantity  because of a new industrial process . The triggering of actuators made with this Cu- Al-Ni  single crystal wire can range from ambient temperature to 200°C in cycling and even to 250°C in on e-shot  mode.  Another advantage of CN -250X is a better shape recovery (8 to 10%) than Ni -Ti (6 to 7%).    Nimesis is the first company able to produce this type of material with  its new  special  industrial  process.  A  characterization study is presented in this  work, includ ing the two main solicitation  modes for this material:    tensile and torsion. Different tests measure the shape recovery of Cu- Al-Ni single crystals  wires  during  heating from room temperature to a temperature higher than temperature of end of martensitic transformation.  

Introduction  

Shape memory  alloys  (SMA)  are recognized as reliable and efficient materials particularly to design  actuators. The major drawback of these shape memory actuators is the trigger temperature that is lower  than 100°C with standard Ni -Ti alloys. The new Nimesis Cu -Al-Ni single crystal wire (Figure 1) shows a  transformation temperature higher than 100°C and they are available in round section with a diameter from 0.5 mm to 20 mm. The state of the art and a detailed characterization work made for CNES demonstrated that a Cu-Al-Ni single crystal wire is a very good candidate for space applications that  need trigger  temperatures between 100°C and  200° C. 

Figure 1.  Cu-Al-Ni single  crystal  Ø2.2 -mm wires  made  with special  Nimesis process  

Experimental Approach  

Single  crystals were produced by a Nimesis special industrial process  that is derived from the Bridgman  process (1) (2). Dimensions of wires were 2 mm in diameter, and 70 to 300 mm in length. The advantage in  using  single crystals is that the preferred orientation of these crystals (close to [001]) obtains  a maximum                                                         * Nimesis  Technology , Mecleuves,  France   ** CNES, Toulouse, France   

Proceedings of the 43rd Aerospace Mechanisms Symposium, NASA Ames R esearch Center, May 4-6, 2016
186 reversible strain of about 8 to 10%  (3) (4 ). This preferred orientation is due to the high elastic anisotropy of  the material.  

Figure 2.  Relation between transformation strains and crystal orientation (3) 

Some Cu 82.4wt% -Al 13.5wt% -Ni 4.1wt% single crystal samples were mainly tested in tensile and torsion  mode. The evolution of the deformation during a thermal cycle and w ith imposed force (shape recovery)  was measured. This test was performed for more than 10 thermal cycles. Transformation temperatures  were controlled by DSC (Differential Scannin g Calorimetry) until 25 cycles.  

Thermomechanical tests  

The objective of these tests is to obtain data relati ve to thermomechanical behavior of the Cu- Al-Ni single  crystal wire produced in industrial conditions.  

DSC tests Results  Table 1 shows  the evolution of transformation temperatures (As, Af, Ms, Mf) for polycrystalline (before  monocrystalliz ation  process ) and single crystal (after monocrystallization process ). There is a small  variation of transformation temperatures during the monocrystallization process.  

Table 1.  DSC results on Cu-Al-Ni polycrystal and single crystals.   description  Mf (°C) Ms (°C) As (°C) Af (°C)  Cu-Al-Ni polycrystal  118 152 149 163  Cu-Al-Ni single crystal  134 153 157 163 

Figure 3 show s the evolution of temperatures during thermal cycling between 25 to 25 0°C and between 25  to 200°C . The transformation temperatures are more stable in cycling when the  maximum  temperature  is limited  to 200° C. 

Tensile  Test Results  Wire samples are manufactured and tests are done with a tensile testing machine equipped with special  grippers and extensometer. Heating is achieved with a direct power supply (Joule Effect) of the sample. Temperature is measured at three different locations: in the center of the sample, just above the extensometer and just below the extensometer. This ensures heating the test zone of the sample   homogeneously.
187  

Figure 3.  Evolution  of transformation  temperatures  during thermal cycling  (a) between 25  and 250°C, (b) between 25 and 200°C  

Two preliminary tests allowed to evaluate the behavior of the material at room temperature and at 220°C,  Figure 4  show s results of tensile tests at room temperature and at 220°C.    Other  tests are done  with a preload of 150 MPa before heating. Successive thermal cycling from  25°C to  250°C results in measuring evolution of the strain of the martensitic transformation.  During the cycling,  transformation temperatures were recorded.    Figure 5 present s transformation temperatures and strain  as a function of the number of thermal cycles.   Contrary to other High Temperature Shape Memory Alloys, deformation and transformation points remain constant  until 25 cycles and probably over (t est to be done).  

Figure 4.  Tensile  tests of Cu-Al-Ni single  crystal  samples  at room  temperature  (martensitic state) and at 210°C (austenitic state)
188       (a)                                                                            (b)  

Figure 5.  Evolution of (a) strain and (b) transformation  temperatures for a prestressed  CuAl-Ni single  crystal  (150MPa)  and during thermal  cycling  from  25°C  to 250°C  

Torsion tests   Torsion tests were made with Cu- Al-Ni polycrystalline samples, Cu- Al-Ni single crystal samples and Ni -Ti  samples  for comparison. Length of each sample was 70 mm.  Each sample is fastened between one fixed  end and one end on which a bulk is set in order to induce a torque.  Torque value varies between 0 and   0.5 N -m. Heating is achieved by a heat gun able to reach a temperature up to 200°C.  Torsion angle is  measured initially at room temperature and then after heating at 200°C  after recovery shape. Shear strain  γ and shear stress τ are calculated from these data.  Results of these tests on Ni -Ti are in accordance with  those in the literature (5)(6 ). This establishes  a comparison between Ni -Ti and Cu- Al-Ni in torsion.  Recovery  shape rate is globally the same between Ni -Ti samples and Cu- Al-Ni polycrystalline samples. But ∆γ is  lower for  Cu-Al-Ni single crystals.  

Thermomechanical behavior   Ratio dσ /dT of Ni-Ti (~6 MPa/°C) is higher  than the ratio d σ/dT of Cu- Al-Ni single crystal  (~2.3 MPa/°C) .  That means for the same temperature range, and for the same power rate, activation stress of a N i-Ti  actuator will be approximately twice higher than the activation stress of a Cu- Al-Ni single crystal actuator.  Furthermore, for the same stress, it takes about twice more heating for a Cu- Al-Ni single crystal actuator  than for a Ni -Ti actuator.  

Electr ical behavior   We can heat by Joule Effect Cu-Al-Ni components to change the temperature of the material, as we can  heat by Joule Effect Ni -Ti components.  That involves taking into account the difference of resistivity  between both materials.  

Table 1.  Comparison  between Ni -Ti and Cu -Al-Ni resistivity   Ni-Ti Cu-Al-Ni  Electrical resistivity ρ  (average  between austenite and martensite)   10-6 Ω.m 0.9  0.12
190   Figure 7.  Comparison of Ni -Ti and Cu -Al-Ni σ-T slope and consequences on actuator  activation  (a) for a given temperature, (b) for a given stress . 

�𝑅𝑅𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁 𝑅𝑅𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑁𝑁𝑁𝑁=𝐼𝐼𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑁𝑁𝑁𝑁 𝐼𝐼𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁=𝑈𝑈𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁 𝑈𝑈𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑁𝑁𝑁𝑁~ 2.7 𝑡𝑡𝑡𝑡 3.5 

For the same dissipated power:   𝐼𝐼𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑁𝑁𝑁𝑁 ~ 3×𝐼𝐼𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁                               𝑈𝑈𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝑁𝑁𝑁𝑁~𝑈𝑈𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁 3     Conclusion  

Results  obtained  with the new CN -250X by Nimesis showed a very good stability during the thermal  cycling in terms of shape recovery (8 to 10%) at 150  MPa for trigger temperature below 200°C.  Higher  temperatures (until 250°C)  can be used for one- shot applications or for applications with a small number of  cycles.  Cu-Al-Ni single crystal wire seems to be able to be made into high temperature actuators  (Figure  8), thermal safety devices, locking- unlocking devices , low shock mechanisms, and deployment  mechanisms . Nimesis is now able to manufacture Cu- Al-Ni single crystal wire (diameter between 0.5 to   20 mm) in large quantity with a new pat ented industrial process , controlling the entire process from alloy  casting to wire grinding. This allows supplying High Temperature SMA over  the long term.  

Figure 8. Examples of actuators made with Cu-Al-Ni single  crystal  wire     As  ∆T  ~ 6 MPa/°C   ~ 2.3 MPa/°C   σ  ∼ σ/2  Ni-Ti  Cu-Al-Ni  Cu-Al-Be  As  ∆T’  ~ 6 MPa/°C   ~ 2.3 MPa/°C   σ'  Ni-Ti  Cu-Al-Ni  Cu-Al-Be  T   T