ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
0123456789 20 40 60 80 100 120 percentage of full voltagestep size (micron)step siz e Figure 11 – Demonstration Of Partial Stepping On An Early SRM Prototype   In another demonstration to test the capability for producing micro-stepping in an IMPULSE PiezoMotor™  device, DSM ran an early “light duty” SRM with a variable voltage on the extender. Figure 11 shows the resulting step size as this motor was driven a few steps to characterize the step size. The partial step size  follows the voltage applied to the extender in a lin ear and proportional man ner indicating that overall  resolution of the motor might be made smaller using proportionally smaller extender steps.  Measurements of Electrical Power Input to the IMPULSE PiezoMotor /g149 Using an accurate data acquisition setup, DSM engineers measured the electrical power going into each  channel of the IMPULSE 30 prototype as a function of drive voltage, step rate and static load (weight)  applied to the output of the motor. Two different drive voltages, multiple drive step frequencies and  multiple static load values were tested. The outcome of the testing is captured in Figure 11. DSM used linear amplifier electronics in this study to make the measurements; current and voltage signals are better  captured with linear amplifiers instead of motor electronics. With the linear amplifiers, the step rate was  limited to 500 steps per second.   To make a measurement of output power efficiency, DSM measured the output mechanical power of the  motor while pulling a range of static loads (weights). DSM found that the efficiency was very low since the extender stack has much more mechanical force capacity than can be manifested by the clamping  elements. In other words, the main pushing stack of the motor can produce 130 N (30 lbf) of drive force  but is only called upon to produce up to 30 N (7 lbf) of drive force because of clamp limitations. Since DSM’s motors are friction limited, the excess capacity of the extender simply goes to waste.   Figure 12 shows the electrical power used to drive the motor as a function of static load (weight) that the  motor is lifting. The electrical power measurements were made for each channel (extender and clampers)  along with the motor displacement for 25 steps at 200 steps per second while lifting the indicated mass. The mechanical power is the product of lifting force and motor velocity. At 200 Hz, the velocity is  approximately 4.5 mm/s under zero weight. Velocity decreases with increased lifting mass as indicated by  the green displacement line. The peak mechanical power correlates with lifting around 1800 grams (3.5 lbm). 12
00.20.40.60.811.21.41.61.82 0 5 10 15 20 25 Static Force (N)Power (W)  00.40.81.21.622.42.83.23.64 Efficiency (%)Power Extender Power Clamper Mechanical Power Efficiency Figure 12 – Electrical Power Used In DSM’s IMPULSE 30 At 200 Hz Step Rate  From this data, DSM gains information regarding how the electrical power is used in the motor actuator.  First, the clamp stack electrical power does not vary as a function of the mass that the motor is lifting.   The extender channel electrical power shows only a small correlation with the increased mass and even  with no lifting mass, the extender uses over 1.6 Watts of power. The small increase in extender power correlates with the increase in mechanical power indicating that any work that the extender is required to  produce while lifting mass requires proportionally more electrical power.   The mechanical power increases with the lifting force until the motor drive force becomes friction limited.  Once the lifting force exceeds the available friction force, the motor begins to slip during its forward  motion and the mechanical power decreases. The efficiency is the measure of the output mechanical power divided by the total electrical power applied to the motor. Peak efficiency numbers are  approximately 2.5%. DSM estimates that there are two reasons for the low efficiency numbers. The first  involves the oversized nature of the extender stack used in the motor. The second reason involves the  electrical properties of the particular piezoceramic material that this motor uses.   Using a smaller extender stack can cause the motor efficiency to increase since the motor drive force is  friction limited not limited by the extender stack size. Another method for increasing the efficiency of the  motor would be to use piezoelectric ceramic materials that are by composition more efficient than the soft  PZT materials used in the current motor prototype. The current motor prototype uses piezoelectric  ceramics with a loss factor of over 5% and a relatively high amount of capacitance. DSM is considering  the use of piezoceramics with less than 40% of the loss factor and approximately 50% of the capacitance of the soft piezoelectric ceramics. DSM estimates that this might lead to a doubling of the current  efficiency numbers.   Piezoceramic motors have a significant advantage in duty cycle over electromagnetic motors. In actuator  duty cycles where holding maneuvers are required, DSM ’s motors use only the quiescent power that is  required to maintain the drive electronics in a ready state. The piezoelectric motors do not require any power to hold position. Therefore, even 18 Watts of powe r for the 10 to 20 ms us ed to make a move does  not require significant battery energy. With the same setup, DSM measured the power as a function of  step rate for the IMPULSE 30 SRM. The power was measured for step rates up to 500 steps per second and then extrapolated for higher frequencies. DSM found a direct linear correlation between electrical  power going into the motor and step rate.   13
Conclusions   In the IMPULSE PiezoMotor™ technology, DSM has developed a new class of high force piezoelectric  SRM mechanisms. The operation of the motor and the drive force, step-size, and characteristic step impulse profile are presented. Compared to conventional step and repeat motors, DSM has produced a  family of devices with substantially greater drive force. Re sults from a study of various potential friction  interface materials yields a set of materials with suitable wear performance and with coefficients of friction that are in the range of 0.15 to 0.18. Modulating the voltage on the SRM extender to obtain smaller steps  is demonstrated as a means to in crease the step resolution of the output. To demonstrate the electrical to  mechanical conversion potential in the SRM mechanisms, DSM performed an experimental study that involved lifting various weights and measuring resultant speed. For the current family of actuators, drive  efficiency is around 2.5%. A means of obtaining higher levels of drive efficiency is discussed.  Measurements also indicate that the electrical power increases proportionally to the motor step rate.   The proposed actuators offer the following significant advantages over conventional electromagnetic  actuator technologies.   /g120 the ability to withstand higher (200 /g113C) and lower (-150 /g113C) temperatures,   /g120 zero power draw during hold maneuvers,  /g120 the ability to carry a significant side load,  /g120 greater impact resistance due to the solid-state nature of their construction,  /g120 fewer number of components that leads to a more reliable system,   /g120 lack of required lubricants for improved storage characteristics, and,  /g120 a much smaller form factor for the same level of force.   References   Spanner, Karl, 2006, “Survey of Various Operating Principles of Ultrasonic Piezomotors, Proceedings of  Actuator 2006, June 9, 2008, Bremen, Germany.  Carman, Dunn, Friedmann, Hahn, Ho, Kim 2001, “Developing Innovative Actuator Devices for Use on  Rotocraft Systems” U.S. Ar my Research Office.  Burleigh, 2005, “Prototype Actuators”, The Power of Precision, Burleigh, An EXFO Company.  Kinetic Ceramics, 2004, “High Pressure Piezoelectric Pump”, Kinetic Ceramics website:  http://www.kineticceramics.com/pdf _files/turnkey_pzt_systems.PDF  EXFO, 2007, Inchworm Motors W-800/810, Web page specification sheet at http://www.exfolifesciences.com/nano/app_note s/IW-800.pdf  May, William, 1975, “Piezoelectric Electromechanical Translation Apparatus, U.S. Patent 3902084, Aug.  26, 1975.  Mudhivarthi, S., D. P. Hess, 2006, “Wear data from friction pairs for microscale piezoelectric actuators”, in  Tribotest, Volume 11, Issue 1 , Pages 1 – 10, Published online 9 Mar 2006.  14
Figure 1.  High Resolution Rotary Actuator The linear drive unit is composed of:  - a redundant two-phase permanent magnet stepper motor  - a redundant rotational potentiometer (fine)  - two linear potentiometers (nominal and redundant) (coarse)  - a roller screw  - ball bearings  - metallic bellows  - ring metallic joints  - oil  - hard stop  The reducing unit is composed of:  - metallic strap  - free flex bearing  - ball bearings  - hard stop  - two outputs Three patents are filed for this product.   /g2 1st innovative idea: the reducer : (Patent: Folio 652805)  /g2 2nd innovative idea: combined guiding: (Patent: Folio 652667)  /g2 3rd innovative idea: The specific crossing guiding with flexible blades (also called free flex pivot)  (Patent: FR0753521 27/02/2007): 

The system requires deployment and then pointing around two axes. To fulfil this function, two HR/g1A are  mounted together in a gimballed configuration to form the MADPM; the layout is shown in Figures 2 – 4. 

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Deployment Once the reflector is released, the stepper motor of the linear drive unit is powered on. The stepper motor  drives the bolt of the roller screw in rotation. As the screw is stopped in rotation by the bellows, the screw  moves in translation. The linear drive unit output step is equal to 2.2 10-3 mm/step. The rotational  potentiometer is linked to the stepper motor rotor to provide fine position. The linear potentiometer is  linked to the screw to provide coarse position.  - The strap support bracket, linked to the linear drive unit output moves in translation.  - Straps unwind and wind at the same time around the first pulley.  - The first pulley radius is 20 mm.  - The sector with a higher radius (63 mm) turns in the same movement. Its straps unwind and wind in the  same time around the output pulley.  - As a consequence, the output step is equal to: step radmmmm mmmm output /02.0 00035.0200022.0 2063° = = /g2 = /g1   End of deployment:  At 1.25° before the operational deployment position, a pointing hard stop on the output pulley comes in  contact with the rod. As the rod supports the first pulley and sector, the rotational movement of both is  stopped with respect to the rod. There is no more movement of the first pulley ball bearing and output  pulley ball bearings. As the linear drive unit continues to push the strap support bracket, the rod unsticks  from the preload rod bracket and moves the free flex pivot. The output rotational movement is obtained by  bending of the three blades of the free flex pivot. The end of deployment is when the potentiometers give  the right value. This position corresponds to a rotation of the free flex pivot of 1.25°.  In pointing phase In this phase, the linear drive unit can move in two ways. The free flex pivot is always bending. The  operational range is ±1° (specification) but might be increased up to ±1.25° (design margins). The output step value is given by the distance between the output rotation axis and the axis of the linear drive unit   (63 mm). The range of HR/g1A movement is limited thanks to the hard stop inside the drive unit. stepmmmm mmloutput linear output / 00202.0630022.0arctan63arctan_° =/g7 /g8/g6/g4 /g5/g3=/g7/g7 /g8/g6 /g4/g4 /g5/g3/g1= /g2   Linear Actuator Description and Maturity  The linear drive actuator is a sealed linear actuator with a complete oil bath. This technology enables a  high number of micro-cycles in a harsh thermal environment. The movement is performed due to the  screw of a spindle. The nut of the spindle is linked to the rotor of a stepper motor. A redundant rotational  potentiometer gives the position of the stepper motor (fine potentiometer). A redundant linear potentiometer gives the position of the screw (coarse potentiometer). The combination of both  potentiometers’ information gives the position of the screw with accuracy inferior to the step. Power and  measurements are sent by two hermetic connectors, one nominal, and one redundant. The dynamic  sealing is performed by metallic bellows (which stop the spindle screw in rotation) and static sealing due  to metallic joints.  18
Figure 5.  Potentiometer assembly The stepper motor, the spindle, the potentiometers, the oil, the ball bearings, the bellows, the joints and  the hermetic connectors are procured elements and represent 90% of linear the drive unit.   Both bellows at the front and back of the linear drive actuator are the same in order to have no variation of volume inside the mechanism. However, it is still necessary to have a volume balancer due to the  thermal expansion of the oil. Actually, the inside volume of the mechanism is constant but the mechanism  is not fully filled of oil. The volume not used by the oil if filled with a neutral gas. The oil / gas ratio is  calculated such that the maximum pressure is not exceeded at temperature.  Figure 6.  Metallic bellow                       Figure 7.  Hermetic connector The oil is the same as the one used on the heritage Scan Drive Unit mechanism. It has the main  characteristic to not have emulsions even in a moving bath. It can survive the radiation environment  without degradation.  The screw of the spindle has a diameter of 12 mm. The spindle is composed of 7 rollers with a solid  preload. The solid preload allows a reversibility limit higher than the elastic preload. The lubrication  environment of the spindle has no effect on the reversibility limit. The main requirements to the supplier  were the reversibility and the resistive torque. 

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Figure 8.  Stepper motor and roller screw assembly The ball bearings are super duplex back-to-back mounted with a solid preload.  The main characteristics measured for this unit are:  /g2 sealing: <1.10-9atm-cm3/s under helium at 50000 Pa  /g2 linear resolution of 0.0022 mm/step  /g2 linear range: 24 mm  /g2 Torque margin >3  /g2 Maximum load capability = Reversibility load. (This is due to the duty cycle voltage command of  the stepper motor)  /g2 Qualification Temperature: [-50°C; +100°C], the drive unit temperature is maintained up to 10°C  with its own thermal control.  /g2 Vibration: 25g mounted in HR/g1A configuration  /g2 Velocity: nominal 2.1 mm/mn, tested successfully up to 26 mm/mn   /g2 Mass <2 kg  The linear drive unit has been fully qualified and six flight units are on one spacecraft. 

Figure 9.  Stepper motor and roller screw assembly  Reducer unit  20
The reducing unit is a mechanism that transforms the linear movement of the drive unit to a rotational  movement with accuracy and high stiffness, with an output range of 180° for deployment and ±1° for  pointing. The output step resolution is 0.02° for the deployment and 0.002° for the pointing. In the range  of pointing, the design of the mechanism is free of any tribological link to ensure a high cycle life time.  There is no movement of ball bearings. The transformation of the translation in rotation is performed by  metallic straps winding and unwinding on a pulley.  

Figure 10.  Reducer unit assembly  21
Design development and qualification plan  At linear drive unit level This product was based on the heritage of the Scan Drive Unit mechanism. All the suppliers have been  kept to reduce the risks with regard to the chemical environment of the oil and gas. But due to the repackaging of the mechanism, all the supply units have been reduced in size. The main concern was the  internal wiring of the mechanism. Indeed, the number of cables was more important than heritage number  because there was no coarse potentiometer on the Scan Drive Unit. These cables had to be routed in a  far more compact design compared to heritage. That is why a mock up of the linear drive unit in Plexiglas  was built to verify the internal cable routing. This mock up allowed validation of the internal design of the  drive unit.  Figure 11.  Mock up of the drive unit internal cabling Once the QM was assembled and tested, six flight linear drive units were assembled in parallel and  submitted to a complete acceptance test including functional and mechanical characterization tests  (sealing, motorization margin, reversibility, motion range, max output load, power consumption…).  At reducer unit level  Due to very stringent planning constraints, the delivery schedule imposed from the start of the project  forced production of the flight hardware in parallel of the QM model. It was therefore decided to verify the  capability of the metallic straps and the free flex pivot new design to perform the number of cycles  required at the earliest stage. Mock-ups were built to validate the design.  Metallic strap mock up Strap design:  One of the issues with the strap design wais the resistance of the interface under strap load. Either the interface is held by friction, or is held by opposition. In the first case, we need to know the friction  coefficient and the tension in the screw to guarantee the link. In the second case, we need only to verify  the capability of the strap under peening and solicitation under clevis but we are limited by the thickness  of the strap.   The first mock up test was to verify the threshold tension load for which the stiffness behavior of the  metallic strap winding on a pulley is linear.  22
Figure 12.  Stepper motor and roller screw assembly 0.0E+005.0E+051.0E+061.5E+062.0E+062.5E+063.0E+063.5E+06 0 50 100 150 200 250 300 350 400 450 500 Load (N)Stiffness (N/m)

Figure 10.  Metallic strap stiffness behavior This test showed that the strap must be tightened to a minimum of 300 N to have linear behavior. This is  due to the local bending around the output of the strap with the pulley.  The second mock up objective was to verify the capability of the strap in life time. During the life time, the  straps wind and unwind locally on a pulley. So the strap sees constant stress due to tension and an  oscillation stress due to the wind and unwind on the pulley.  Before and after life test, a dye penetrant test was performed on the strap to verify the non presence of  crack.  Free flex pivot mock up  Due to the design, the behavior of the free flex under an imposed rotation is non linear. So we needed to  verify by test the predicted behavior with regard to stiffness, the back torque and the buckling.  The first mock up consisted of three sample blades fully identical to the flight one to verify if the non linear  model was good.   Released  metallic   strap  pulley  Loading  device   Loading sensor  23
0123456 0.0 0.5 1.0 1.5 2.0 2.5 Rotation (°)Actuation torque (Nm)Analytic prediction

Figure 13.  Free Flex mock up 1                   Figure 14.  Free flex stiffness behavior correlation The second mock up consisted of a free flex fully representative of the flight one. The objective of this test  was to verify the limit of buckling of this design when it was submitted to a bending moment. For this, the  free flex was equipped with a strain gauge all along both sides of the three blades. The test is performed  in imposed displacement and the buckling is detected when the strain gauge signal becomes non linear.  /g1  /g1 Detection of the buckling /g1 Signal of strain gauges  Strain gauges Strain gauges  Figure 15.  Detection of the free flex buckling       Figure 16.  Free flex equipped with strain gauges  The results obtained confirm the prediction.  At HR/g1A level  The objective of the development was to qualify the MADPM with only one HR/g1A. That is why the  following test plan has been performed with some particularity for the vibration and shock test.  24
Assembly of QM  Physical measurements  Functional performance Tests  at ambient  Stiffness and Quasi Static test  Functional verification Tests  at ambient  Vibration test   Functional verification Tests  at ambient  Shock Test  Functional verification Tests  at ambient  Thermal vacuum test   Life time under Thermal  vacuum   Functional verification Tests  at ambient  Final Functional verification  Tests  at ambient  Damping Test  Final Inspection  Disassembly and Expertise  Figure 17.  HR/g1A Assembly  Vibration and shock test  The HR/g1A was tested in vibration in three configurations. The first configuration corresponded to the  HR/g1A in position 1 on the MADPM and loaded by the HR/g1A in position 2. The HR/g1A in position 2 was  simulated by a dummy mass representative in mass, Cdg position and inertia. This dummy mass was  connected to the test support thanks to a tool representing the reflector arm stiffness.  25
The second configuration corresponded to the HR/g1A in position 2 on the MADPM. In this configuration,  the HR/g1A QM was submitted to the envelope level of the configuration one and the level seen by the  interface of the dummy mass of the first configuration.  Figure 18.  First vibration configuration test     Figure 19.  Second vibration configuration test 

The third configuration corresponds to the HR/g1A vibration configuration of the complete flight model. In  this configuration, the HR/g1A QM only saw low level sine. This allowed a comparison of the flight model  behavior with the qualification model. This configuration is close to the first one with no spacecraft  bracket.  Figure 20.  Third vibration configuration test  At MADPM level In order to deploy and then point around two axes, two HR/g1A are mounted together in a gimbal  configuration to form the MADPM; the layout is the presented in Figure 21. Figure 22 shows the MADPM  (Multimedia Antenna Deployment and Pointing Mechanism) assembly and on the spacecraft (3 flight unit  on the same spacecraft)  26
Lessons Learned  One of the main challenges was to develop a new mechanism and deliver flight hardware in 24 months.  The design of the HR2A is far from the heritage design. The first lesson learned was that the schedule  challenge was made possible only because technologies involved in the design concept were well  assessed before the development (blades, straps, oil bath, sealing).   The second lesson learned concerns the suppliers. Major design evolutions compared to the heritage  were analyzed deeply and led to no surprise for this development. Due to the size reduction needed,  some components were slightly modified. Suppliers were kept unchanged compared to the heritage for all  components. New requirements ended up being not well taken into account due to lack of close  communication and reviews with the suppliers.  The third lesson learned concerns the way to manage FM hardware integration in parallel to QM  assembly and testing. A QM is a first model and always needs some adjustments. It was decided to  tackle the FM deadline with two rules:  - allow assembly or test step on FMs only when the QM operation step had been performed and  return of experience well taken into account  - the engineering manager is part of the production tiger team and work in the clean room on both  QM and FM models  The bet was that even though the QM planning was drifting due to first adjustment needed, the FM  delivery date would be kept by having clear production file and learning experience of the operators. It  was challenging not to delay some QM testing in order to deliver the flight models more quickly.  The fourth lesson learned concerns the difficulty of comprehension of the design (detailed kinematics,  consequences of failure modes …). To help the understanding, we built a Plexiglas mock up. Thanks to  this mock up, most of the points raised were more easily addressed. This mock up helped to understand  and solve the difficulties met during integration. It also eased the communication with the final customer  during design reviews.  28