ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
Figure 9.  Plot of Balancing masses, im balance and balance force and bar graph Post Vibration Spin Balance Verification (without RDA/MR) Following the completion of GMI vibration tests, the instrument was spun again on October 5, 2011 to  compare with the pre-vibe imbalance measurements carried on August 2, 2011. The test is intended to  check for possible shift of cabling and other flexible components. The difference between the two tests  amounts to 0.26% in the radial force and 0.48% in the radial moment. It has to be noted that in addition to  several changes to the stationary GMI hardware which theoretically would not affect the measurements (as long as we do not excite their modes), there have been slight changes in the configuration of rotating GMI that included the replacement of two 36 GHz flex wave guides, 0.0410 lb (0.183 N) each, with two  rigid wave guides, 0.0168 lb (0.0747 N) each, and the re-machining of mounting shims. The wave guides  along with the 36-GHz filter were re-staked, and one balance mass was removed, adjusted to account for  the change, and then reinstalled in the same spot and re-staked. The overall delta is Wt = -0.051 lb (0.227 N). The new radial load is analytically evaluated and compared well with the measured value, placing all shifts at 0.106%, that is a delta of 0.005 lb (0.022 N), significantly less than the derived  requirement of 0.08 lb (0.36 N) (or just 6.7% of the requirement). Therefore, it is safe to state that  /g89/g76/g69/g85/g68/g87/g76/g82/g81/g3/g79/g82/g68/g71/g86/g3/g71/g88/g72/g3/g87/g82/g3/g79/g68/g88/g81/g70/g75/g3/g90/g76/g79/g79/g3/g79/g76/g78/g72/g79/g92/g3/g86/g75/g76/g73/g87/g3/g87/g75/g72/g3/g85/g82/g87/g68/g87/g76/g81/g74/g3/g80/g68/g86/g86/g3/g69/g92/g3/g26/g8/g15/g3/g82/g85/g3/g79/g72/g86/g86/g15/g3/g82/g73/g3/g87/g75/g72/g3/g85/g72/g84/g88/g76/g85/g72/g80/g72/g81/g87/g3/g82/g73/g3/g19/g17/g19/g27/g3/g79/g69/g3 /g11/g19/g17/g22/g25/g3/g49/g12/g15/g3/g82/g81/g16/g82/g85/g69/g76/g87 .  In-Vacuum Final GMI Balancing Several tests were carried out in vacuum and in air on the dynamometer to show that the requirements  were met. It is worth noting that an RDA/MR deployment GSE off-loader structure needed to be removed  from Brutus to perform clean test measurements. Table 2 shows the average of three separate measurements of forces, moments and computation of static and dynamic imbalances first in vacuum and then the averages of three other 32-rpm tests also run in the Brutus but in open air rather than in vacuum. Table 3 shows the computed and actual masses that brought GMI to meet requirements.  315
Table 2. Average of imbalance measurements (three in vacuum and three in air) units  (lb,in) Fx (lb) Fy (lb) Fr (lb) Mx (lb·in) My (lb·in) Mr (lb·in) me (lbm.in) Jrz (lbm.in2) Vacuum 0.0021 0.0402 0.0436 -0.069 2.805 2.8 1.5 73.5 Air -0.0098 0.037 0.0398 -0.86 1.104 1.5 1.4 63.9 Requirement   0.08   10 2.77 187 units  (Kg,m) Fx (N) Fy (N) Fr (N) Mx (N.m) My (N.m) Mr (N.m) me (Kg.m) Jrz (Kg.m2) Vacuum 0.0092 0.1794 0.1946 -0.008 0.318 0.318 0.017 0.022 Air -0.0438 0.1651 0.1775 -0.097 0.125 0.167 0.016 0.019 Requirement 0.36 1.13 0.032 0.055    Figure 10. GMI Integrated on the GPM Spacecraft at NASA Goddard Space Flight Center 316
Table 3. Added masses used to balance GMI Conclusion The Global Microwave Imager instrument (GMI) was successfully spin-balanced using a dynamometer as  a mounting fixture. GMI was balanced to less than 0.017 kg-m (1.47 lbm-in) static imbalance and 0.022 kg-m 2(75.2 lb-in2) dynamic imbalances, meeting the requirements of 0.032 kg-m (2.77 lbm-in) and  0.055 kg-m2(188 lb-in2) respectively, total for the 123-kg (271-lb) spinning portion of the instrument  payload.  The successful final precision spin balancing of the GMI instrument in vacuum demonstrated the  capability of this method to accurately measure the static and dynamic imbalances, and to precisely compute the optimal set of minimal balance masses, accounting for various. The ability to precisely  measure the imbalances before and after environmental testing also enabled us to very accurately predict the magnitude of the change in the GMI instrument imbalance on orbit, following launch.  The forces measured by the dynamometer checked well against two other independent measurement  systems. In addition, the dynamometer is shown to be capable of reproducing the applied loads and moments with adequate accuracy. The natural structural frequencies of the dynamometer were mapped and their effect on the measurements was identified for the frequency spectrum of interest.  Prior to balancing GMI, both moderate and extreme imbalance risk mitigation tests are shown to be  accurately measured using the dynamometer and the necessary balancing forces are accurately computed. The fully balanced state was also recovered from the time traces of the resultant radial loads and radial moments. Since the successful completion of the final spin balance activity, the GMI instrument was delivered to  Goddard Space Flight Center in March 2012, and was successfully integrated onto the GPM spacecraftlater in June 2012, see Figure 10. The GPM spacecraft just recently completed spacecraft level Thermal  317
Vacuum (TVAC) testing in January 2013, vibration testing in July 2013, post-environmental testing in  September 2013, and is scheduled to be launched in February 2014 from Tanegashima, Japan on a JAXA MHI-H11A rocket. A special thanks to Sergey Krimchansky**; GMI instrument COTAR at GSFC for his input over-seeing the  technical work on GMI and for his support in writing these GMI-related technical papers. References 1. Newell, D., Rait, G., Ta, T., Berdanier, B., Draper, D., Kubitschek, M., Krimchansky, S. “GPM  Microwave Imager Design, Predicted Performanc e and Status”, Proceed ings of the 2010 IEEE  International Geoscience and Remote Sensing Symposium (IGARSS) Publication Date: July 25, 2010.  2. Woolaway, S. Kubitschek, M., Berdanier, B., Newell, D., Dayton, C. and Pellicciotti, J. “GMI Spin  Mechanism Assembly Design, Development, and Test Results”, /g51/g85/g82/g70/g72/g72/g71/g76/g81/g74/g86/g3/g82/g73/g3/g23/g20 /g87/g75/g3/g49/g36/g54/g36/g3/g36/g72/g85/g82/g86/g83/g68/g70/g72/g3 /g48/g72/g70/g75/g68/g81/g76/g86/g80/g86/g3/g54/g92/g80/g83/g82/g86/g76/g88/g80 , Langley Research Center, May 2012.  3. Koss, S., Woolaway, S. “Lessons Learned From the WindSat BAPTA Design and On-Orbit Anomalies”, Proceedings of 38th NASA Aerospace Mechanisms Symposium, Langley Research Center, May 2006. 4. Pierre, W. “GMI Spin Mechanism Structural Analysis”, BATC Internal SER Report No. 2307821B, Ball  Aerospace and Technologies Corp., Nov. 2008. 5. Richard P. Wolley, Dynamic Balancing Without Spinning: A New Method for Unwieldy Satellites, SAWE  paper No. 1670, Category 6.0, 44th Conference of the Society of Allied Weight Engineers, 1985.   6. 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. 318
The European Robotic Arm: A High-Performa nce Mechanism  Finally on its way to Space H.J. Cruijssen*, M. Ellenbroek*, M. Henderson*, H. Petersen*, P. Verzijden* and M. Visser*  Abstract This paper describes the design and qualification of the European Robotic Arm (ERA), which is planned to be launched by the end of 2015. After years of changes, a shift of launcher and new loads, launch preparation is underway.  The European Robotic Arm ERA has been designed and manufactured by Dutch Space and its  subcontractors such as Astrium, SABCA and Stork with key roles for the mechanical aspects. The arm was originally designed to be launched by the STS (mounted on a Russian module for the ISS) in 2001.  However, due to delays and the STS disaster, a shift was made to the Russian Proton rocket. ERA will be launched on the Multipurpose Laboratory Module (MLM). This module, which is now planned for launch to the ISS in 2015, will carry the ERA. The symmetrical design of the arm with a complete 3 degree-of-freedom wrist and general-purpose end effector on both sides, allows ERA to relocate on the station by  grappling a new base point and releasing  the old one, and move to different working locations.   ERA Overall Design Description The arm consists of 2 limbs which are  connected by motorized hinges. The arm has an end effector which has the possibility of grabbing Space Station components for transport or tools for support of EVA activity.  This end effector includes other features  such as electrical connection s and a  mechanical drive that can operate like a  wrench tool. The arm is symmetrically  designed, meaning that the arm shoulder  joints and wrist joints are identical. This  allows the arm to “walk” fully autonomously  from base point to base point on part of the ISS. This “walking” arm capability allows it  to reach remote grapple points.  The arm structural capability enables it to  move 8000-kg payloads. The arm is  controlled by an integrated computer and has a camera vision system for close proximity operations and can provide camera images of the working area.           Figure 1.  Overall ERA arm architecture *Dutch Space BV, Leiden, The Netherlands /g51/g85/g82/g70/g72/g72/g71/g76/g81/g74/g86/g3/g82/g73/g3/g87/g75/g72/g3/g23/g21/g81/g71/g3/g36/g72/g85/g82/g86/g83/g68/g70/g72/g3/g48/g72/g70/g75/g68/g81/g76/g86/g80/g86/g3/g54/g92/g80/g83/g82/g86/g76/g88/g80/g15/g3/g49/g36/g54/g36/g3/g42/g82/g71/g71/g68/g85 /g71/g3/g54/g83/g68/g70/g72/g3/g41/g79/g76/g74/g75/g87/g3/g38/g72/g81/g87/g72/g85/g15/g3/g48/g68/g92/g3/g20/g23/g16/g20/g25/g15/g3/g21/g19/g20/g23/g3 wrist elbow  End effector  319
ERA has been designed from the beginning to be serviceable and to allow exchange of big parts via EVA  in case of failure or an emergency situation. Such parts are called ERU (EVA Replaceable Units). During the launch of STS 132 in 2010, one ERU was launched and put into in space. It has been stored on the outside of the ISS on the MRM-1. A special launch interface had to be designed to allow launch in orbit. This ERU is still fixed in this launch configuration and is protected with a special bag of MLI. In case of  failure or specific maintenance, the arm can be activated by EVA. ERA is also designed to perform servicing tasks originally allocated for EVA.

The main technical characteristics are listed in Table 1.

                     Table 1.  ERA Key Characteristics  Total Length Range/span     Degrees of Freedom   Mass      Peak power dissipation    Stand-by heat dissipation   Hibernation heater power  Accuracy open loop    Accuracy closed loop   Maximum moveable mass   Maximum payload dimensions  Maximum speed of movement   Braking distance at max joint speed11.3 m 9.2 m 7 630 kg 800 W 420 W250 W± 40 mm ± 5 mm8000 kg 3x3x8.1 m0.10 m/s 0.15 m

The ERA consists of the following major subsystems:  1. The End Effector Subsystem (EES) consists of two Basic End Effectors (BEE), Base Points (BP)  and Grapple Fixtures (GF). 2. The Manipulator Joint Subsystem (MJS) consists of two wrists and one elbow. Each wrist is made  of 3 joints (roll, yaw and pitch) and one electronic box for their control. The elbow is made of one joint  (pitch) also with its own electronic control box. 3. The Manipulator Limb Subsystem (MLS) consists of two limbs of carbon fiber reinforced plastic  material. 4. The ERA Control Computer subsystem (ECC or On board Computer, OBC), is the brain of the  system that communicates with the Space Station through the external data bus and with each  subsystem through the internal data bus. 5. The Camera and Lighti ng Unit subsystem (CLU) consists of 4 units. One on each End Effector and  one on each side of the elbow mounted on the two limbs. Other key elements are related to the manual control of ERA. These are: 6. The EVA Man-Machine Interface (EMMI) is a control panel that provides the capability to control  ERA during EVA. 7. The IVA Man-Machine Interface (IMMI) control panel is a laptop computer for control of ERA from  the pressurized modules of the station. The EVA-MMI is a dedicated console with switches and LED displays, designed to be operated by a crew  member in EVA suit and able to be exposed to the space environment for extended periods of time. The IVA-MMI is a software application running on an IBM system which is located inside the pressurized module of the Russian Segment of the ISS. The workstation near the IVA-MMI will be able to display ERA camera views. 320
ERA Mechanical Subsystems and Mechanisms The first two above mentioned subsystems represent mechanical subsystems composed of mechanical  assemblies. These main subassemblies are:  1.End Effector Subassembly (EES): a) Grapple mechanism (GM) – incl. Base point (BP) and Grapple Fixture (GF) b) Integrated Service Tool (IST) (incl. receptacle in GF) c) Torque Force Sensor (TFS) incl. the Torque Rigidization Mechanism (TRM) 2.Manipulator Joint Subassembly (MJS) consisting of 3 modular hinges of which all are very similar ,  except the roll. These 3 hinges form together the so called “wrist” joint. See Figure 1 for the  overview. a) Pitch Joint / Yaw Joint / Roll Joint; located at both ends of the arm (3 D.O.F) b) Elbow Joint:  The elbow joint uses the same basic hardware as the wrist pitch joints but  has only one degree of freedom. A further major mechanical subsystem is: 3.Launch Fixation Mechanism :  Its function is to restrain the ERA during launch. The launch fixation mechanism on the Russian Segment-MLM structure consists of: a. Fixation Hooks and support pads, being part of the MLMb. Pins and support pads, being part of the ERA structure These mechanisms will be activated by EVA, when the unfolding of the arm from the launch support  starts. The cosmonauts will release the fixation hooks. Furthermore, special mechanical features are included to allow for EVA. These are implemented to enable repair maintenance, exchange, etc. The design and the size of certain mechanism are driven by the accessibility requirements for EVA tooling.  4.EVA-Compatible Mechanisms :  a. Camera & Lighting Unit (CLU): The connector mate/de-mate mechanism. b. EVA Man-Machine Interface (EMMI); only switches. c. EVA overrides for GM, IST, TRM and joints.d. EVA ERU mate/de-mate mechanisms (Elbow/Wrist, CLU, CLU windows).  e. EVA placeable handrails. N.B. For a., c. and d., special EVA tools are used. The above four mechanical subsystems and mechanisms are described below:

End Effector Subassembly (EES) Mechanism Design Details  During the operations in orbit, one end effector is connected to a base point in order to provide a  sufficiently stiff connection between the Russian Segment of ISS and ERA and to transmit power, data  and video signals for the operation of the ERA system. The second end effector then serves as the gripper, able to grapple an object outfitted with a grapple fixture or a basepoint. Furthermore, the second end effector will support ERA by monitoring force/torque values during the insertion/extraction and during  the transportation of objects. The second end effector provides mechanical and electrical power to the grappled object and allows for data transfer. In order to provide the above mentioned capabilities, the following functions are assigned to the EES: /g120measure torques/forces /g120grapple/guide /g120power, data and video transfer /g120insert the Integrated Servicing Tool (IST) head to provide mechanical power /g120provide sufficient stiffness. /g120rigidization, if no measurement of torque/for ce is needed (by design implementation)  321
movement, the IST receptacle provides a compliance capability. A sensor will detect the proper IST head  insertion. A redundant set of Hall sensors will provide the necessary data for the Electronics Unit to control the IST actuation. Moving platform                             Spindle socket                               Clamp            Connector   Figure 2. Grapple mechanism with mov ing table showing the 3 clamps  and 3 connectors (retracted) /g26/g17/g3/g37/g68/g86/g72/g3/g51/g82/g76/g81/g87/g86/g3/g11/g37/g51/g29 The base points are mechanically identical to the grapple fixtures. They do not  contain the receptacle for the IST but they provide all system harness connections between ERA and the  Russian Segment of ISS. They contain the female parts of the three system harness connectors, through  which the power, signal and video data for ERA operation are routed. The base points also provide the  mechanical interface between the grapple mechanisms on the end effector side and the Russian Segment of ISS on the other side.  /g3

Figure 3. Base point and engage ment hook of end effector 324
Manipulator Joint Subsystem (MJS) Mechanism, Design Details ERA is approximately 10-m long and has to move large payloads. At the same time, the mass of ERA  had to be limited to comply with launch requirements. Its mass is about 620 kg. This makes ERA a much more flexible (elastic) arm than most industrial robots. The first bending mode of the arm is important, as  it contains more than 90% of the total inertia. It is the dominant mode to deal with for control. The  combination of compactness, limited weight, high stiffness, small backlash, long life time, and thermal vacuum circumstances put high constraints on the development of the joints and the hinge unit .  The wrists and elbow joints are composed of three joints. The pitch and yaw joints are very similar in  design. The pitch joint provides a rotation around the Y-axis, the yaw joint around the Z-axis, and the roll  X-joint axis. (See Figure 5 below for axis definition).  The wrist contains an electronic box, which drives all the 3 motors independently. Redundancy is included  as well in the electronic device via 2 PCBs. Hence, the shoulder joint and the wrist contain a separate  electronic box for the drive function, i.e., power and telemetry functions. This is also the case for the  elbow. This box is located as a rectangular box in between the limbs and forms part of the structural load path. Hence, the size and the stiffening of the box have been implemented with plates equipped with ribs.  /g3 /g3  Figure 4. The elbow joint  for pitch motion. Showing the EVA hand rails and the  2 CLU’s. In the middle of  the hinge is the EVA receptacle hole. /g3 Each joint consists of the following mechanical elements:  1. Motor unit: Motor, resolver including the Joint Position Sensor for the feedback of the joint position to joint control electronics and brake. 2. Gearbox assembly: Four-stage planetary gear train for torque capability and speed reduction  including the bearings including lubrication / grease (N=450) 3. Motor housing and yoke. In addition, an EVA access provision is included for manual override. Other non-mechanical elements  include:   /g120Cables and connectors; crossing wires passing the joint for external use and entrance wires  being connected to electrical components within the joint /g120MLI thermal hardware, heaters /g120Cable covers / Connector covers.  325
/g3 Figure 6. Elbow joint without cables cover:  ribbon cables (data & power) separation wall. Figure 5. Elbow joint and brackets  launch interfaces; pins and hard plates . Details of the mechanical elements are described below. /g20/g12/g3/g55/g75/g72/g3/g80/g82/g87/g82/g85/g3/g88/g81/g76/g87 : The motor, resolver and brake are integrated as mechanically self-contained device,  which interfaces with the Mechanical Unit of the hinge. This unit consists of the following items: a)Motor : The motor is based upon a permanent magnet synchronous motor (often called brushless  DC motor) and has a two-phase redundant winding. The electronics are adjusted in such a way that the motor provides a ripple-free torque. For this purpose but also for commutation reasons, a resolver is used, providing the instantaneous position information required by the current-torque controller.  b)Resolver : The resolver is built with a primary winding supplied with a high-frequency voltage,  inducing a high-frequency signal in each of the two secondary windings. Both of these signals  have an amplitude related directly to the rotor position (e.g., varying respectively with the cosine and sine of the angular position). The analysis of these two signals allows detection of the instantaneous rotor position of the electrical motor drive shaft.  c)Joint Position Sensor: The sensor measures the angular rotation of the arm joint at the exit axis  and provides the angle position input to the joint control electronics. Each Joint Position Sensorcontains a redundant set of read stations, light emitting diodes, digital signal processing circuitry, and cable harness. d)Brake: A brake is integrated into the joint, providing the braking torque by the contact of two  smooth friction surfaces. When the brake coil is not energized, the brakes are engaged, provided by an adequate axial force created by eight dedicated springs (which provide on average a total  of approximately 85 N of force). Conversely, the brakes are disengaged by supplying the coil with  a constant current, effecting separation of the two braking surfaces by magnetically attracting the moving armature fixed to the axially-translatable brake disc. A microswitch position sensor  provides the brake status information (i.e., whether the brake discs are in contact with one  326
This compensation is realized by the introduction of flexibility to several components. The pitch  joint has been equipped with several details by which flexibility is introduced. Because the motor is made of AISI 420 (steel) and the housing material is aluminum, a thermal problem may occur. In order to make it possible that the motor can expand freely, for the coupling between motor and housing the same coupling with square teeth has been used as for the housing and ring wheel connection. /g22/g12/g3/g43/g82/g88/g86/g76/g81/g74/g3/g68/g81/g71/g3/g92/g82/g78/g72 : The yoke structure is replaced by a cylinder rotating around the fixed housing. The  hinge construction of the joint consists of two major parts, the housing and the yoke. The housing is the  “fixed part”, being the part in which the driving components (gear train and motor) are connected. The yoke is the part that rotates around the housing (the “moving part”). The housing contains the gear train including the EVA-device, the motor, the Joint Position Sensor and cabling. It also supports the main  bearings. End stops are incorporated. The housing is designed sufficiently stiff by flanges at the end to  reduce radial deflections. Loads shall be transferred with sufficient strength and stiffness of the housing to the main bearings. Care is taken to ensure that loads are equally distributed around the main bearings and excessive loads on the main bearings due to thermal expansion are prevented.  Launch Fixation mechanism /g47/g68/g88/g81/g70/g75/g3/g38/g82/g81/g73/g76/g74/g88/g85/g68/g87/g76/g82/g81 : The ERA arm is located in the launch position on this MLM module. Interfaces to  the end effector are: /g120the Base Points, which are fixed to the Russian Segment of ISS /g120the Grapple Fixture, which are fixed to objects to be handled by ERA. Both base points and grapple fixtures are part of the end effector subsystem. During launch, both end  effectors are grappled to a special base point, each acting as a load suspension system. During the hibernation phases in orbit, both end effectors are also mated to base points. In this configuration all electrical connectors will be mated to the Space Station.

Figure 7 Illustration of ERA in the “Charlie Chaplin”  configuration for launch Figure 8.  Schematic illustration of a Launch  fixation point for the MLM /g3 328