ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
Chip qualification campaign  In parallel of the previous TRP activity, a complete qualification of the chip itself, in accordance with  space standards for the qualification of monolithic chip, is undertaken. Tests foreseen in this chip qualification activity can be divided in three steps:  /g131 The production control tests which occur at the manufacturer level  /g131 The screening tests  /g131 The qualification tests 

Production control tests

The wafer lot acceptance tests occur at the manufacturer level: The manufacturing of the wafers is monitor and PVM data are recorded during the whole process. The final lot is inspected through scanning electron microscope. Then, in-process controls occur at the packaging level: After a pre-encapsulation visual inspection, bond strength and die shear tests are implemented. After the chip encapsulation, a dimension check of each packaged chip is performed.  Screening tests These tests are performed on all the components. Screening tests consist mainly to reject faulty chips though hard electrical and temperature testing. During those tests, the drift parameters of the chip are monitored and compare to failure criteria. The following tests are foreseen:  /g131 The serialized chips are subjected to a high temperature stabilisation bake (24h at 150°C) to  determine the effect of storage at elevated temperatures without electrical stress applied. Drift parameters are monitored and control during the entire test.  /g131 The chips are then be subjected to several burn-in tests at 125°C (reverse bias and power burnin) in order to eliminating marginal devices, those with inherent defects which cause time and stress dependent failures. Drift parameters are monitored and control during the entire test.  /g131 A measure of the drift parameters at ambient temperature is then foreseen and allow for the lot  qualification.  /g131 Before a final visual inspection of each chip, test of the quality of the package sealing are  foreseen as well as evaluation of the ability of the terminations of the package for solderability.   Qualification tests

The parameters of these tests are the same as presented in the technology qualification campaign.  These tests are performed on a minimum of 45 chips. 3 subgroups are constituted and follow  respectively:  /g131 Mechanical tests (15 chips): Vibration, shock, constant acceleration and seal tests followed by a  visual inspection are foreseen in this subgroup. Drift parameters are measured along the tests.   /g131 Environmental tests (15 chips): Thermal shock, moisture resistance and seal tests followed by a  visual inspection are foreseen in this subgroup. Drift parameters are measured along the tests.  /g131 Endurance tests (15 chips): Lifetime and seal tests followed by a visual inspection are foreseen in  this subgroup. Drift parameters are measured along the tests.  183
Conclusion The absolute angular position sensor presented here offers several advantages over common  conventional potentiometer for space applications; based on a contactless technology, it offers a high reliability for long-term lifetime missions. Combining a Hall ring sensitive structure and control electronics with modern CMOS technologies, it gives the possibility to manufacture miniature accurate sensors. With  this technique, the angular position can be obtained by a simple phase detection method, increasing the reliability of the whole system for harsh space environments.  The device has already been tested in ambient condition [8] and the results fulfill the expected  performance of the sensor gathered in Table 4. The technology qualification of the sensor has just started and will be followed by the qualification of the chip itself. The reliability against vibration and shock loads is not considered as an issue for a sensor with such dimensions. Thanks to both radiation tests, one within the TRP activity before the other during the chip qualification campaign. The reliability of the chip against radiations (TID and SEE), allows for a progression margin and to a complete validation of the layout radiation hardness. Last point, but not least, is to verify the stability of the high accuracy of the  sensor along the whole temperature range (define actually to -60°C to +90°C) and, with regards to the  results, to propose an upgraded range of functional temperatures to increase the space applications panel covered by this contactless angular position sensor.  Table 4. Functional performances of the APS sensor Specifications Value Operational lifetime > 10.106 (theoretically /g146)  Orbit lifetime > 15 years  Storage lifetime 5 years  Weight < 100g (magnetic configuration depending)  Mechanical range 360° continuous  Measurement type Absolute  Speed of rotation < 1 RPM  Accuracy /g148 0.05°  Resolution < 0.01 °  Repeatability < 0.01 °  Stability < 1 ppm/°C 

References

1.   “Angular Position Sensor based on MEMS Technology”, ESTEC/Contract No. 20404/06/NL/CP. 2.   http://lmis3.epfl.ch/ 3.  Law L. "Angular Position Sensing with 2-axis Hall ICs”, Sensors  (http://www.sensorsmag.com ), March  2003.  4. Volder J. E. “The CORDIC Trigonometric Computing Technique”, IRE transactions on  ElectronicComputers, vol. EC-8, no. 3, 1959, 330-334.  5.  Popovic R. S. “Hall Sensor and Method of Operating a Hall Sensor”, Patent number EP1679524 A1,  12.07.2006.  6. Popovic R. S. “ Hall Effect Devices ”, Adam Hilger (IOP – Institute of Physics Publishing), 2nd edition,  2004, pp. 261-264.  7. Raich H. “ Design and Construction of a Dipolar Halbach Array with a Homogeneous Field from  Identical Bar Magnets: NMR Mandhalas ”, Concepts in Magnetic Resonance Part B (Magnetic  Resonance Engineering), Vol. 23B, 2004, pp. 16-25.  8. Reymond S., “True 2D CMOS integrated Hall sensor”, IEEE sensors 2007.   184
Electrically Powered Separation Nuts  Barney Little* Abstract  Traditionally, over the past 50 years, space mechanisms have been powered by pyrotechniques (pyro).  Pyro-powered mechanisms provide the greatest power-to-weight ratio of all types of mechanisms. HiShear Technology Corporation, a major supplier of pyro-powered devices, has developed two new  electrically powered separation devices, a separation nut and a cable release device.  Advantages of Electrically Powered Separation Devices Hi-Shear’s electrically powered separation devices have advant ages over pyro-powered devices, some of  which are:  1.) Resettable  Hi-Shear’s electrically powered separation devices are resettable for up 25 times (tested 50  times) with out disassembly or refurbishment.   2.) No Pyro  Hi-Shear’s electrically powered separation devices have no pyro, which provides the following  advantages: - No special explosive handling or storage.  - No stray voltage or bridgewire resistance tests required.  - May be installed at any time on the vehicle assembly line. - No special access covers required for electrical tests.  - No pyro shock.  3.) No Out-gassing  Hi-Shear’s design does not depend on elastromeric seals to prevent liquid or gaseous emissions.  4.) Ultra-Low Shock  Hi-Shear’s electrically powered separation nut produces only 1% of the shock energy of a pyro separation nut. The release of bolt preload, which is the greatest contributor to shock, is slowly  performed through a helix. Pyro shock ha s been eliminated since there is no pyro.  5.) Easy Usable Power Hi-Shear’s electrically powered se paration nut uses only 15 watts at 28 VDC of power and does  not require special firing circuits.  The Hi-Shear electrically powered separation devices provide reliable separation systems using mature  release technology.  Introduction  Hi-Shear has been designing and producing separation nuts since 1964. All of these separation nuts use  the same basic bolt release system. Figure 1 shows the functioning of the basic bolt release system.  Figure 1a shows the bolt release system in the pre-actuation condition. Three or four threaded segments  are held radially together by a load ring or collar. The segments are seated on a base keyseat that  prevents the segments from rotating during bolt torquing. The seating plane between the segments and the base keyseat is at a slight angle to provide outward radial loading during bolt loading and post  * Hi-Shear Technology Corporation, Torrance, CA  Proceedings of the 39th Aerospace Mechanisms Symposium, NASA Marshall Space Flight Center, May 7-9, 2008  185
Lessons Learned  The original separation nut design used a DC brush motor. The DC motor drove the cam ring through a  worm gear drive. The motor drew a lot of power and took a long time to actuate the nut. The cam ring was  modified to be driven by the nut preload and a simple catch is used to release the cam ring.  Conclusion  Non-pyro electrically actuated separation nuts provide the following advantages over pyro-actuated nuts:   -  Resettable   -  No LAT required   -  No out-gassing   -  Ultra low shock  -  No special explosive handling or storage  Figure 1a. Before Actuation Figure 1b. After Actuation  Figure 1. Hi-Shear’s basic bolt release system  187
Rollers in Unlocked  Position Figure 4. Cam Assembly Release Mechanism Rollers in Locked  Position Inner Ramp is held in  Compression from the Bolt/Segment Pre-Load • Roller Bearings (3 ea),  120 Degrees Appose • Rollers Located On  Ramps, Locking the Inner and Outer Ramp From Releasing Lever Arm Not Rotated,  in the Locked PositionOuter Ramp Inner Ramp is held in  Compression from the Bolt/Segment Pre-Load • Roller Bearings (3 ea),  120 Degrees Appose • Rollers Located On  Ramps, Locking the Inner and Outer Ramp From Releasing Lever Arm Not Rotated,  in the Locked PositionOuter Ramp Figure 5. Cam Assembly in the Locked Position  189
Inner Ramp Fully DescendedWave Spring Lifts  Locking Ring Off the  Segments Segments Driven Outward,  Releasing the Bolt From the Nut Bolt is Released From the Nut, Bolt Extractor Required to Separate the Bolt  From the Nut Assembly Inner Ramp Fully DescendedWave Spring Lifts  Locking Ring Off the  Segments Segments Driven Outward,  Releasing the Bolt From the Nut Bolt is Released From the Nut, Bolt Extractor Required to Separate the Bolt  From the Nut Assembly Figure 6. Cross Section SN9700 in the Actuated Position  190
A Radiation-Hardened, High-Resolution Optical Encoder for Use in   Aerospace Applications  Pat Kreckie* Abstract  Advances in aerospace applications have created a demand for the development of higher precision,  higher accuracy, radiation-hardened encoders. Historically, encoder products have proved somewhat deficient due to precision, accura cy, weight, and alignment concerns. MicroE Systems’ Mercury II  aerospace encoder design provides the precision and accuracy required by these applications while also  addressing radiation, weight, and alignment concerns. The encoder is a grating-based, reflective,  interferometric encoder consisting of three major components: a scale, a readhead, and processing  electronics. The system is a kit design that is easily configured and forgiving of misalignments. Its large  tolerance of tilts and translations during setup and operation, make this design ideal for aerospace requirements.  The system is small in footprint and weight and requires minimal power for operation. The  ability to attach multiple readheads to one processing electronics unit, as well as its alignment tolerances,  makes it versatile enough to meet the most demanding applications.  Background  An optical encoder is a device that uses optical sensi ng of some sort to determine the position of a  surface with respect to the system’s sensor head. Typical systems consist of a scale, a sensor head(s),  and processing electronics (Figure 1). Encoder systems may be linear or rotary, reflective or transmissive,  kit or packaged, incremen tal or absolute.   MicroE Systems’ Mercury II encoders are grating-based interfero metric encoders. Light from a source  within the sensor head is incident on the scale. The scale attaches to the surface being monitored. The  scale is a glass substrate containing a periodic grating structure. The incident light reflects and diffracts  from the grating. The diffracted beam re-enters the sensor head and forms interference fringes on a detector array. The processing electronics calculate the interference fringe pattern’s spatial phase from  the detector array signals. Scale movement (surface movement) results in fringe pattern movement  across the detector array. The processing electronics re-analyze the resulting fringe pattern and produce a system output corresponding to the surface’s new position. 

Figure 1. Encoder Components                                                             * MicroE Systems, Natick, MA 

Proceedings of the 39th Aerospace Mechanisms Symposium, NASA Marshall Space Flight Center, May 7-9, 2008  191
Mercury II™ Aerospace Encoder  Optical Design.   The optical system (Figure 2) consists of multiple light sources, a window, a scale, and a  detector. Single-mode vertical cavity surface emitting lasers (VCSEL) are the system’s light sources.  Each VCSEL emits 850nm diverging beams with excellent spatial and spectral coherence. In this design,  four VCSELs are used – primary and redundant VCSELs for the Main signals and primary and redundant VCSELs for the Index signals. Although VCSEL lifetimes are excellent,  the redundant set further  improves the reliability of the system. VCSELs offer many advantages over other laser sources including  excellent mode stability, low current draw, and very long lifetime. The vertical cavity design allows for emissions from the surface of the die, simplifying its mounting, eliminating the need for additional beam  directing optics and facilitating an extremely small system footprint.  Scale Design – Main Track. The Main and Index VCSELs illuminate the Main Track and Index Track  sections of the scale, respectively. Each VCSEL generates a diverging beam that passes through a  window (not shown) and exits the sensor head.  The scale’s Main Track section is an optical chrome-on-glass grating with a 20-μm period. The incident  Main VCSEL beam reflects and diffracts into multiple overlapped beams from this scale region (Figure 3).   

   Figure 2.  Optical System Layout           Figure 3.  Main Track Diffracted Beams  These beams reenter the sensor and illuminate a four-channel Main Track detector array. Since multiple  coherent beams overlap on the detector, interference fringes form on the Main Track array (Figure 2)  according to the well-known Talbot effect. This effect, when illuminating with a point source, governs the  shape, period and contrast of the fringes. [1]  Due to the grating’s square-wave design with a duty cycle of roughly 50-50, the even diffracted orders are  suppressed and the fifth and higher orders are relatively weak leaving the zero, first and third orders as  dominant. The Gaussian distribution of the VCSEL beam further reduces the power of the higher orders  at the detector; so the interference fringes formed at the detector are primarily generated by the interference of orders 0, 1 and 3. The detector is situated in a Talbot plane where  the grating is “self  imaged”; so, given the limited set of orders contributing to the interference, the fringes consist mainly of  the fundamental with the third harmonic.    192
As the scale moves, the diffracted orders shift either up or down by various amounts depending on the  order of each particular diffracted beam. This phase shifting causes the interference fringes to move  across the array resulting in a modulated current from the detector. Given fringes that are well defined by  the physics of the Talbot effect, the resulting signal modulation is predictable and controllable.  Scale Design – Index Track .  The Index Track section of the scale contains three regions: two (2) end  switches and a binary lens (Figure 2). The end switches are highly reflective regions used in the  continuous automatic gain control of the VCSELs’ output energies during operation. The binary lens  region is the index mark for the system. The binary lens creates a focused line of light on the detector as the index VCSEL beam sweeps across this region. This index pulse defines the “home” position of the  system. Because the binary lens is a physical re ference on the scale, it is highly repeatable.  Detector Design – Main Track .  The detector is a silicon photodiode with excellent response at the 850  nm wavelength of operation. The die has two separate arrays: one for sensing the main encoder position  signals (Main Track) and one for detecting the index pulse (Index Track) (Figure 2). The main detector  region is an interleaved array of 120 cells grouped together to generate four output signals T0, T90, T180 and T270. One optical fringe spans four of the cells, with each of those cells feeding one of the four  output channels with a spatially phased modulated current.  There are 30 detector quads and 30 fringes across the length of the main array (Figure 2). The detector  samples the sinusoidal optical fringe pattern every 90°: 0°, 90°, 180°, 270°. By grouping the photodiodes  in an interleaved fashion, each signal is the averaged sum over 30 periods across the entire fringe  pattern. These four signals are amplified and differenced to create the analog sine and cosine signals,  which are subsequently digitized and interpolated. 

Unlike conventional encoders, small sensor-to-grating gap changes do not have a detrimental or  unpredictable impact on the fringe quality. Therefore, the detector and electronics can be designed with  foreknowledge of the fringe cha racteristics, and tuned for the very best response and filtering. In  particular, the main detector array cells have been designed to filter out the third harmonic in the interference fringe  pattern. These active  cells are arranged in a zigzag pattern (Figure 4).  193
Figure 4.  Main track array (dimensions in microns)  The zigzag shape causes the cells to cut across the  fringes over a prescribed distance, washing out the  third harmonic to generate high fidelity sinusoids, thereby ensuring very high encoder accuracy. With  optical harmonic distortion minimized, only electric al offset, electrical gain mismatch, and electrical  distortion remain as the primary sources of error.  Detector Design – Index Track.   The detector’s Index Track is separated into three (3) regions:  two (2)  end switches and one (1) index region (Figure 2).    As the Index VCSEL beam sweeps across the scale’s end switch regions, the beam uniformly reflects  onto the Index region of the detector.  The de tector’s end switch regions sample the beam’s energy and  perform automatic gain adjustments to the detector’s signal amplifiers  and a current adjustment to the  corresponding VCSEL.    As the Index VCSEL beam sweeps across the scale’s binary lens, the resultant line of focused light is  incident on the detector’s index region. The index region consists of 3 cells arranged in a linear array. As  the grating moves, the focused lin e of light sweeps across this three -cell array generating three analog  pulses. Comparator circuitry generates a very robust index window  (IW) digital pulse, roughly one main  track cycle wide. The IW is subsequently gated with the interpolator output to yield a one-LSB wide index  pulse.  Mechanical Design and Alignment Tolerances.   The encoder system accommodates multiple angular and  translational motions. Conventional encoders based on geometric optics typically require the alignment  between the sensor hea d and the scale remain within very tight tolerances. In contra st, the interferometric  approach employed in the aerospace encoder system permits both a large operating gap between sensor and scale and a very generou s operational alignment envelope.  By using a diverging beam from a VCSEL light source, the encoder sensor head can tip and tilt with  respect to the scale, while still directing sufficient energy to the grating that diffracts and reflects back to  the sensing array in the head. The diffracted beams overlap throughout a large distance along the optical  z-axis to form interference fringes that are sensed by the array anywhere within that region. Because the  system does not have an intermediate optic between the scale and the detector, the optical fringes do not distort throughout the alignment tolerance range (Figure 5).  194
Figure 5. Sensed interference fringes  These key features differentiate the Aerospace Encoder from other options. The very forgiving initial  alignment conditions and the large tolerance of tilts and translations along axes other than the measurement axis during encoder operation, make this design ideal for aerospace requirements. Table 1  outlines the alignment tolerances of the Aerospace Encoder. The values reported in the table are based  on reduction in analog signal amplitude only and represent a conservative range.  Table 1. Alignment Tolerances  Axis Mercury II Aerospace  Y /g114 300 /g151m  Z /g114 200 /g151m  Theta Z /g114 2/g113  For ultimate stability through temperature, the sensor mounts with either screws or adhesive along the yaxis in line with the VCSEL and detector, thereby minimizing drifts due to thermal expansion.  Electrical Design .  The electronics design is based upon the second generation of MicroE’s Mercury  incremental encoder. All of the analog signal processing is performed in a mixed mode ASIC, while the digital processing occurs in an FGPA. A/D converters provide the interface between the analog signals  and the digital signal processing. The signal processing is ratiometric, making it insensitive to common  mode changes, and the processing algorithms utilized are either not affected by single event upsets (SEU) or quickly recover from upsets without permanent change. For more information, see the Upset  Effects section.  Analog Signal Processing.   All analog signal processing is performed in a mixed mode ASIC. There are 4  signals generated from the multi-element, interleaved, main track photodetector array (0 /g113, 90/g113, 180/g113, and  270/g113). Transimpedance amplifiers convert these currents to voltages. The 0 /g113 and 180 /g113 signals are  subtracted and amplified to form differential, high-level sine signals while the 90 /g113 and 270 /g113 signals are  subtracted and amplified to form differential, high-level cosine signals. The signals from one  photodetector section comb ine with the corresponding signals in the other. The high signal to noise ratio  obtainable in the design provides high-speed operation and still interpolates to 14 bits (1.22 nm). This  high signal-to-noise ratio also allows for a low noise encoder.   The combined sine and cosine signal s are applied to a dual, high  speed, A/D converter, located in the  sensor head. Three in dex signals generated from the detector  array form the index window used to  identify a home position. The Transimpedance amplifiers convert the index currents to voltages in the  ASIC. These signals are processed to form two complementary, high-level signals, which, in turn are  applied to the inputs of a comparator. The comparator output is the index window. Additional processing occurs during the digital signal processing.   The ASIC also contains the laser drivers. These are controllable current sources, with built-in over-current  protection for the VCSELs and circuitry for selecting either the primary or the redundant VCSELs.   195