CN105784237B - A kind of Micro-thrust test system and method - Google Patents

A kind of Micro-thrust test system and method Download PDF

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Publication number
CN105784237B
CN105784237B CN201610318356.9A CN201610318356A CN105784237B CN 105784237 B CN105784237 B CN 105784237B CN 201610318356 A CN201610318356 A CN 201610318356A CN 105784237 B CN105784237 B CN 105784237B
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thrust
measurement
micro
test
personal computer
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CN201610318356.9A
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CN105784237A (en
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李飞
余西龙
郭大华
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中国科学院力学研究所
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L25/00Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency

Abstract

The present invention discloses a kind of Micro-thrust test system, and it is suitable for 1~1000mN, thrust-weight ratios 10‑5~10‑2The test of thrust in range substantially increases measurement accuracy in the case where Measurement bandwidth is enough.It includes rack, displacement sensor, on-line proving component, damping system, computer measurement and control equipment;The computer measurement and control equipment includes connected high-frequency data capture card, industrial personal computer, display device;The displacement data of reflective laser displacement sensor acquisition shows after being handled by industrial personal computer by display device;Industrial personal computer controls the height of lifting platform, and stable state thrust calibration is realized in the pendulum thrust response under the load of measurement standard counterweight;Industrial personal computer controls damping system to keep rack static.Additionally provide the test method using this device.

Description

A kind of Micro-thrust test system and method

Technical field

The invention belongs to the technical fields of physics, are more particularly to a kind of Micro-thrust test system, and using this The test method of system is mainly used for 1~1000mN of thrust, thrust-weight ratio 10-5~10-2The test of thrust in range.

Background technology

The characteristics of microthruster is that thrust is smaller, and for general thrust in hundreds of milli ox magnitudes, accurate measurement is so small Thrust is relatively difficult.For microthruster, it can also be worked with impulse form, and therefore, there is only how to measure small push away The problem of power, it is also necessary to measure impulse.For the influence shortened test time, weaken ambient noise, it is necessary to consider platform Frame damps;To avoid the drift tested for a long time, it is necessary to consider the problems of on-line proving thrust.Therefore, high-precision, high environment are reliable Property thrust measurement technology, be one of the technology that must develop in microthruster research.

Microthrust both domestic and external/impulse measurement technology, measurement method can be summarized as two types:

(1) direct method:When thrust is larger, and has an high regard for bigger, thruster is placed directly on load cell, into The direct measurement of row thrust.When thrust is larger, but have an high regard for smaller, often balances thruster using delicate balance rack is designed Gravity, recycle the force snesors such as piezoelectric ceramics, thrust signal be converted directly into electric signal, is followed by amplifier, then acquire Record." zero deformation " feature of piezoelectric transducer becomes the best measuring cell of dynamic response, and frequency can reach several Ten kHz.Therefore, the intrinsic frequency of measuring system depends primarily on scale rack mechanical parts.To improve intrinsic frequency, it is necessary to harden Mechanical part, this necessarily reduces the sensitivity of thrust measurement.In addition, it is limited by the dynamometry lower limit of small-measuring range force transducer, this Kind of force measuring method can only realize compared with big thrust loading in the case of hundreds of mN or more thrust measurement.If being surveyed for smaller thrust Examination, can not ensure enough measurement accuracy.

(2) indirect method:The thrust rack for designing different structure converts thrust measurement to rack displacement or acceleration is surveyed Amount.Common horse structure type includes single pendulum, double pendulum or rocks, it can by demarcate static thrust and rack displacement/ Relationship between acceleration realizes that average thrust measures.This method is also the measuring micro-thrust method being most widely used, Wherein single pendulum structure generally carries out the thrust measurement of mN magnitudes, rocks and is chiefly used in mN, uN even thrust measurement of nN magnitudes.

The above-mentioned quality for using for reference scheme is analyzed one by one, although it is not difficult to find that the Measurement bandwidth of direct method is enough, is utilized Load cell directly carries out mN grades of thrust tests, and measurement accuracy is difficult to meet the requirements.In commercial load cell, range is minimum About 10N (PCB, 209C01), peak response frequency 100kHz, nonlinearity<1%, estimate its measurement accuracy tens of MN magnitudes, measurement accuracy are unsatisfactory for requiring.Also, the thrust-weight ratio very little of most of thruster, such as 10-5~10-2, it is difficult to it utilizes Direct dynamometry.

In indirect dynamometry, often dynamometry is switched to measure displacement or acceleration.In acceleration scheme, measurement is needed to push away Into the change of the front and back rack velocity variations of device igniting, that is, rack momentum, to test average thrust.This method not only needs to survey The speed of test stand frame, and need to carry out the calibration of rack effective mass, meanwhile, the time of thrust application is also required to accurately measure. Compared to displacement method, this method is using less.In displacement measurement scheme, the thrust rack for designing different structure is needed, it will Thrust measurement is converted into rack displacement measurement.It can be realized flat by demarcating the relationship between static thrust and rack displacement Equal thrust measurement.This be the measuring micro-thrust method being most widely used, it can be achieved that down to sub-and micro-Newton micro-force measurement.But The Measurement bandwidth of existing measuring micro-thrust technology is insufficient, it is difficult to while micro thrust and micro- momentum are measured, while needing reality Existing on-line proving and offer ease-to-operate and ambient adaptability.

Invention content

The technology of the present invention solves the problems, such as:A kind of Micro-thrust test system is overcome the deficiencies of the prior art and provide, is fitted It is 10 for thrust-weight ratio-5~10-2The test of the thrust of 1~1000mN in range.It realizes very high Measurement bandwidth, greatly improves Measurement accuracy.

Technical solution of the invention is:The survey of entire dynamometric system is improved using the displacement sensor of high measurement bandwidth Bandwidth is measured, so as to realize that the time-derivative of displacement measures, extracts micro- momentum information;Online design damping simultaneously and calibration system System, weakening environment influences, and the experiment stand-by period is greatly decreased, and improves pendulous frequency.The Micro-thrust test system includes rack, position Displacement sensor, on-line proving component, damping system, computer measurement and control equipment;

The rack is that level rocks structure, including hold-down support, rotary support, flexible axle, cantilever, counterweight, limit turn It sets, thruster fixing device;

Institute's displacement sensors are reflective laser displacement sensor, and the beam signal sent out passes through the side surface of cantilever Reflection is recorded and is handled by its internal CCD after return, to obtain the absolute distance of itself and cantilever side;

The on-line proving component hangs standard test weight using suspension, it is elastic to control suspension by lifting platform, to produce Raw stable state thrust, demarcates microthruster;

The damping system includes coil and iron core, and coil is fixed on the firm banking of rack, when iron core is relative to line Electromagnetism suction and repulsion is generated when circle movement, is rocked to gradually static;

The computer measurement and control equipment includes connected high-frequency data capture card, industrial personal computer, display device;Reflective laser The displacement data of displacement sensor acquisition shows after being handled by industrial personal computer by display device;Industrial personal computer controls lifting platform Highly, the pendulum thrust response under the load of measurement standard counterweight, realizes stable state thrust calibration;Industrial personal computer controls damping system to make torsion It puts static.

The horizontal positioned wiggly table frame of the present invention can not be affected by gravity, and reflective laser displacement sensor obtains The absolute distance of itself and cantilever, on-line proving component demarcate microthruster, and damping system is static to make to rock, reflective The displacement data of laser displacement sensor acquisition shows after being handled by industrial personal computer by display device, therefore suitable for having an high regard for Than being 10-5~10-2The test of range, the thrust in 1~1000mN substantially increases survey in the case where Measurement bandwidth is enough Accuracy of measurement.

A kind of test method using this Micro-thrust test system is additionally provided, is included the following steps:

(1) cantilever is mounted on by the flexible axle of two vertical direction on rack ontology;

(2) after installed thrust device, the level of cantilever is kept by controlling the weight of counterweight;

(3) before testing, it is static to make to rock that industrial personal computer controls damping system;

(4) displacement data of reflective laser displacement sensor acquisition is opened up after being handled by industrial personal computer by display device It is existing;

(5) height of industrial personal computer control lifting platform, the pendulum thrust response under the load of measurement standard counterweight, realizes that thrust is online Calibration.

Description of the drawings

Fig. 1 is Micro-thrust test system structure diagram according to the present invention.

Fig. 2 is the Technology design block diagram of Micro-thrust test system according to the present invention.

Fig. 3 is the structural schematic diagram of damping system according to the present invention.

Fig. 4 is the operation method and installation site figure of damping system according to the present invention.

Fig. 5 is the structure chart of on-line proving component according to the present invention.

Fig. 6 is the basic function schematic diagram of TT&C system according to the present invention.

Specific implementation mode

Micro-thruster is in-orbit need to execute momenttum wheel unloading and attitude-control operation, to meet satellite attitude stabilization degree and essence Degree, needs to accurately control the momentum under thruster pulse operation.To ensure the Pulse Width Control precision of thruster, accurate tool need to be developed There are high bandwidth and high-precision dynameter, is accurately measured with meeting momentum.Since the thruster working time is short, thrust/momentum Small, existing thruster measuring apparatus cannot be satisfied requirement, and micro thrust, micro impulse test system can be tested by needing to develop.

As shown in Figure 1, this Micro-thrust test system comprising rack, displacement sensor, on-line proving component, damping System, computer measurement and control equipment;

The rack is to rock structure, including rack ontology 1, flexible axle 2, cantilever 3, counterweight 4 and thruster fix dress 5 are set, cantilever level is placed, and middle part installation flexible axle is connect with rack ontology, and one end of cantilever places counterweight and the other end connects Thruster fixing device, microthruster are placed in thruster fixing device;

Institute's displacement sensors 7 are reflective laser displacement sensor, and the beam signal sent out passes through the side table of cantilever Face is reflected, and is recorded and is handled by its internal CCD after return, to obtain the absolute distance of itself and cantilever side;

The on-line proving component 8 hangs standard test weight using suspension, it is elastic to control suspension by lifting platform, to produce Raw stable state thrust, demarcates Micro-thrust test system;

The damping system 6 includes coil and iron core, and coil is fixed on the firm banking of rack, when iron core is relative to line Electromagnetism suction and repulsion is generated when circle movement, is rocked to gradually static;

The computer measurement and control equipment 9 includes the high-frequency data capture card, industrial personal computer, display device being connected;It is reflective to swash The displacement data of Optical displacement sensor acquisition shows after being handled by industrial personal computer by display device;Industrial personal computer controls lifting platform Height, the lower pendulum thrust response of measurement standard counterweight load, realization stable state thrust calibration;Industrial personal computer controls damping system to make It rocks static.

Horizontal positioned rock of the present invention can not be affected by gravity, and reflective laser displacement sensor obtains it With the absolute distance of swing arm, on-line proving component demarcates microthruster, and damping system is static to make to rock, reflective to swash The displacement data of Optical displacement sensor acquisition shows after being handled by industrial personal computer by display device, therefore is suitable for thrust-weight ratio It is 10-5~10-2The test of thrust in range substantially increases measurement accuracy in the case where Measurement bandwidth is enough.

In addition, the rack, which is level, rocks structure, including hold-down support, rotary support, flexible axle, cantilever, counterweight, limit Position transposition, thruster fixing device.

In addition, the flexible axle is the flexible axle of model 6016-400.

In addition, the reflective laser displacement sensor is the displacement sensor of model Panasonic HL-C203BE, measure Centre distance is 30mm, and measurement range is ± 5mm, displacement resolution 0.25um.

In addition, the damping system further includes programmable power supply, it is connect with coil.

In addition, the loop length 175mm, diameter 80mm, coil 400 is pricked, 12~20V of operating voltage, surveys impedance 5 Ω;The core length 170mm, diameter 25mm;The programmable power supply model RIGOL DP811A, maximum working voltage 40V, electric current 5A.

In addition, the on-line proving component drafts a calibration 196mN.

In addition, the lifting platform is vertically-mounted electronic control translation stage, stroke 100mm, and by two right angle fixed blocks To fix translation stage respectively and lift counterweight.

In addition, the industrial personal computer is to grind magnificent industrial personal computer IPC-610MB, the capture card is general magnificent multi-function data acquisition card PCI- 3363。

A kind of test method using this Micro-thrust test system is additionally provided, is included the following steps:

(1) cantilever is mounted on by the flexible axle of two vertical direction on rack ontology;

(2) after installed thrust device, the level of cantilever is kept by controlling the weight of counterweight;

(3) before testing, it is static to make to rock that industrial personal computer controls damping system;

(4) displacement data of reflective laser displacement sensor acquisition is opened up after being handled by industrial personal computer by display device It is existing;

(5) height of industrial personal computer control lifting platform, the pendulum thrust response under the load of measurement standard counterweight, realizes that thrust is online Calibration.

The embodiment of the present invention is described in detail below in conjunction with the accompanying drawings:

Thrust range for 1~1000mN and impulse measurement requirement are published according to low thrust measurement aspect Document.The basic rack thrust measurement structure proposed is to rock+whole thrust measurement the scheme of reflective laser displacement system.Tool The horse structure of body is shown in Fig. 1.

In structure shown in FIG. 1, thruster is fixed on a horizontal positioned cantilever, its advantage is that can not be by weight The influence of power.The rotary shaft rocked is in vertical direction.The rotation rocked is completed by two vertically arranged flexible bearings, should Axis belongs to unlubricated component, can both use in air, can also meet the requirement of vacuum environment.The sensitivity of thrust measurement It is related with swing rotary angle.Therefore, when selecting flexible bearing, it is necessary to consider the torque coefficient of bearing.The constant is smaller, adds The angle rocked caused by load unit torque is bigger, and the sensitivity of thrust rack is higher.But not the torque coefficient of bearing is got over It is small better, and the flexible bearing with appropriate torque coefficient should be reasonably selected according to the dynamic range of measurement.

Thruster is fixed on the cantilever rocked, is equivalent to a cantilever beam.In order to fully ensure that rock it is horizontal positioned, with Eliminating gravity influences, and other than the rigidity in reasonable orientation enhancing pendulum, also increases counterweight by the contralateral side in pendulum, eliminates weight Influence of the power to platform system.

Micro-displacement measurement realizes that the principle of the sensor is the reflection change light of laser by laser displacement sensor The position of point on the detector face.Sensor maximum measurement frequency is about 100kHz, and the resolution ratio of displacement is less than 0.1um.Due to The sensor is the industrial sensor of maturation, and reliability, repeatability and ease for operation can be met the requirements.

Thrust test equipment is other than above-mentioned two key element (torsional pendulum type horse structure, laser displacement sensor), also There is on-line proving component;Damping system;With computer measurement and control three parts.Wherein, on-line proving uses standard test weight into rower Fixed, damping system uses electromagnetic damping system, computer measurement and control part to use the knot of industrial personal computer+data collecting card+Labview Structure realizes the control to the measurement of micro-displacement, damping and calibration system.

Fig. 2 is the Technology design block diagram of the test system development.It proposes whole based on wiggly table frame and laser displacement gauge Body scheme, and carried out entry evaluation, it was demonstrated that the feasibility of scheme.In specific implementation, to each component part of equipment into Row dismantling, implements respectively.Whole system can be divided into (1) wiggly table frame, (2) displacement sensor, (3) damping system, (4) calibration system System, (5) computer measurement and control and (6) vacuum match six parts, as shown in Figure 2.In specific implementation process, per part respectively into Row, and in middle and later periods combined crosswise, debugging and verification, the final default purpose for realizing whole equipment.

Entire research process can be summarized as follows:

The first step, for the linear oil-free flexible axle of core element-of horse structure, displacement sensor, observing and controlling industry control Machine and vacuum matching material requested carry out type selecting, purchase;Damping system and calibration system are designed and determine relevant parameter;

Structure, debugging TT&C system hardware and laser displacement sensor are rocked in second step, design, and that purchases damping system can Program power supply, processing coil, purchase counterweight, the lifting platform of calibration system, according to vacuum matching condition, arrange gas on rack, Circuit arrangement;

Third walk, to wiggly table frame carry out Machine Design, combination debugging flexible axle and damping system to verify damping effect, Calibration system and TT&C system are combined, writes, debug lifting platform control software, part is designed for wiggly table frame in terms of vacuum matching Monitoring temperature;

4th step processes wiggly table frame, combination of dampings device and TT&C system, writes the control software of damper.To processing Oil removal treatment is carried out with procuring equipment, to meet vacuum use demand;

5th step combines wiggly table frame and displacement sensor, carries out undamped debugging;

6th step, combination rack, sensor and damping system have carried out damping debugging;

7th step, combination rack, sensor, damping, calibration system and preliminary TT&C software, carries out having under atmospheric conditions Damp rating test;

8th step, under the cooperation for having damping rating test, all subprograms of joint debugging TT&C system, and write, debug The main program of complete equipment;

9th step carries out equipment debugging under vacuum;

Tenth step arranges a variety of materials, writes the documents such as operation instructions, completes equipment construction.

The beam signal that laser displacement sensor is sent out is recorded after the side of cantilever returns by the CCD of sensor internal And handle the absolute distance for obtaining sensor and the sheet metal.Since the sensor has the measurement frequency of 100kHz, energy Enough obtain the absolute value and its time changing curve of displacement (pivot angle), the maximum displacement that can be put in this way, maximum speed And acceleration course, stable state thrust, impulse bit and the acceleration change that thruster is can get in conjunction with static demarcating are bent Line.

The most crucial element of wiggly table frame is flexible axle, it is installed on the middle part of Fig. 1, it is each up and down there are one.The axis both ends Fixed, middle section is rotatable, and internal similar wraping plate has fixed spring constant, therefore be referred to as under certain angle Linear axes.It is not difficult to assess required spring constant according to thrust and momentum test scope and the weight of thruster.Used in equipment Flexible axle model 6016-400, torque coefficient is about 1.85Nm/rad, and it is about 100 kilograms that can hold axial load.

Displacement measurement uses reflective laser displacement sensor, and after laser illumination to body surface, reflected light returns The reception window of sensor, and detected by line array CCD (charge coupled cell) after being collected by lens and be converted to light intensity signal Electric signal, igh-speed wire-rod production line microchip by can be obtained after the data processing of CCD testee apart from the sensor it is absolute away from It can be exported by voltage or current signal from, this distance signal, by computer acquisition and show, reprocess.

With the progress of photoelectric technology, in recent years, the laser displacement sensor based on laser reflection principle has become into Ripe industrial products.Can be as needed, select suitable sensor parameters, including target range, measurement accuracy, sample frequency Deng.

Using frequency:The maximum measurement frequency about 100kHz of the laser displacement sensor, usually carries out in actual use Multiple averaging is to further increase measurement accuracy.Frequency after average depends on most putting on velocity of displacement, and maximum slew rate depends on In maximum thrust and pendulum weight.By taking pendulum weight 15kg, pulse maximum thrust 300mNs as an example:Maximum slew rate should beIt, should be in the distinguishable displacement of sensor as far as possible to obtain real time acceleration information Raising measure points.The optimum resolution of the laser displacement sensor is 0.25um, therefore the measurement frequency of sensor should be big In 80kHz, it is proposed that use 100kHz.

Target range and measurement accuracy:Go out from measurement dynamic range (such as 1~1000mN) angle for maximizing stable state thrust Hair, sensor should be the bigger the better at a distance from tested cantilever.However measurement accuracy is inversely proportional with target range, smaller survey Accuracy of measurement needs smaller target range.The range of displacement measurement of high precision laser displacement sensor mainly has third gear:± 1mm is right Answer target range 10mm;± 5mm, corresponding target range 30mm;± 15mm, corresponding target range 110mm.

Since the best pivot angle of flexible axle is less than 3 °, if pendulum arm length 250mm, according to flexible axle parameter, correspondence is most put on Dynamic displacement 3.25mm, therefore the sensor of measurement range ± 5mm should be selected, corresponding target range 30mm, the type sensor Displacement resolution is 0.25um, selects model Panasonic HL-C203BE.After having selected sensor probe, suitable biography should be equipped with HL-C2CE may be selected in sensor controller.The controller takes into account the power supply power supply of sensor, Laser Driven and returned data Amplification and shaping feature.Controller is for 24V power supplies, it can be achieved that sampling period and the analog voltage output function of 10us, convenient Secondary development.

Due to the without hindrance characteristic of flexible axle, in experiment caused by environment vibration noise slightly swing be difficult to it is voluntarily static.This The influence that kind interference measures minimum stable state thrust (such as minimum thrust 1mN) and minimum momentum (such as 3mNs) is fatal.Cause This, it is necessary to is to gantry designs, installation damping system, for ground, the stability contorting of the vacuum condition bottom.

The damping system of design is as shown in figure 3, include coil 601, iron core 602 and plastics hold-down bars 603.In the design In, iron core and the plastics hold-down bars of damping system are installed below cantilever, and coil is fixed on rack ontology.The calculation of damping system Method after carrying out calculus of differences and denoising and amplified signal, is adjusted inclined as shown in figure 4, according to the displacement information of displacement sensor It sets and Current Voltage is utilized to convert, change electrical current to coil, to change internal magnetic field environment, when iron core is relative to coil Electromagnetism suction and repulsion is generated when movement, coil damps the movement of iron core, i.e., gradually static to rock.The hardware installation of damping system in In vacuum warehouse, and algorithm part is realized by Measurement &control computer, outside storehouse.

The loop length 175mm that this damping device is designed and machined, diameter 80mm, coil 400 are pricked, operating voltage 12 ~20V, 5 Ω of actual measurement impedance;Core length 170mm, diameter 25mm;Programmable power supply model RIGOL DP811A, maximum work Make voltage 40V, electric current 5A.To debug the effect of electromagnetic damper, combination pilot scale study has been carried out.It designs, machined single pendulum knot Structure.Experiments have shown that under conditions of 12V, 0~3A, damping is good, can stop in a few seconds.

The precision of on-line proving system is the key that weigh a Micro-thrust test stabilization of equipment performance, repeatability.Using outstanding The mode of silk suspension standard test weight generates stable state thrust, is demarcated to thruster.And be to realize on-line proving, it improves operable Property, plan uses electric controlled vacuum lifting platform 801, elastic by the suspension 804 of elevating control counterweight 802, to realize that stable state pushes away Power is demarcated.The schematic diagram of calibration system is as shown in Figure 5.The number that the table surface height of electrical-controlled lifting platform 801 is exported by Measurement &control computer Word signal controls, and the distance of movement and the synchronous acquisition of displacement signal, processing have been built in TT&C software.Experiment In, it is only necessary to on-line proving button is clicked in software, you can realizes that the automatic running of electrical-controlled lifting platform, counterweight are hung, displacement is adopted Collection and the conversion of stable state thrust.

The precision of calibration counterweight directly determines the precision of entire calibration system.The Mass accuracy of counterweight has standard class can Look into, the quality error of high-precision counterweight can < 0.1%, stated accuracy demand can be met.Meanwhile hanging the fixed pulley 803 of counterweight Frictional force also contribute to stated accuracy.For this purpose, the gravity of calibration counterweight is not answered too small, it is typically in the range of the 20-80% of full scale, This equipment drafts a calibration 196mN.Calibration point can obtain the stiffness coefficient of flexible axle, be directly used in the conversion of displacement-force.

Since motion range very little, the speed of lifting platform are slow, and its moving parts is excessively unfavorable for vacuum matching use and (removes Oil, friction heat dissipation), therefore vertically-mounted electronic control translation stage in systems in practice, and by two customization right angle fixed blocks, formed and risen Drop system, instead of lifting platform.Thus, the motion range of the jacking system is big (100mm), speed height (>200mm/s), and It is simple in structure, moving component is few, be suitable for vacuum use.Translation stage and right angle block are installed in vacuum warehouse, and control cabinet is installed on storehouse In outer control rack.

After the completion of the hardware of lifting platform system, joint debugging should be carried out with TT&C system.The main purpose of this part work It is to write the control software of lifting platform and debugged.In actual operation, which includes the switch on and off of translation stage, Speed, stroke and acceleration setting, back to zero control, position feedback, and with rock position measurement comparative analysis.This part journey Sequence will be coupled into main program, therefore timing control in the last of equipment development, especially start to trigger particularly critical, need in son It pays attention to when program debugging.

To simplify the operation of equipment and excluding human interference, equipment institute is functional to be acquired and is controlled by computer measurement and control system System.Its basic hardware is constituted:Multichannel, the acquisition of multifunctional high frequency data, output card;Industrial personal computer;(the plan of virtual instrument program Realized using Labview) and peripheral support circuit.

The basic structure of TT&C system is as shown in fig. 6, the data that the core of its collecting part is laser displacement sensor are adopted Collection, since the measurement frequency of sensor is 100kHz, the sample frequency of the analog data acquisition should be set as 500kHz or more.Acquisition The time history of displacement calculate stable state thrust, momentum and dynamic thrust for data processor.These final results, directly It is shown on software interface, it is easy to operate.

In terms of calibration, measurement and control program starts calibrating procedure, and the digital signal by acquiring vacuum lifting platform judges lifting platform Highly, control signal is exported using preset program, which is converted to ± 24V direct currents, when using the output for controlling signal The altitude location of long control lifting platform (801) restarts pendulum displacement acquisition program, and the pendulum thrust measured under counterweight load is rung It answers, realizes stable state thrust calibration.

In terms of damping system, the on and off of TT&C system control damping.When needing damping, software switch is opened, it is built-in Damping control software start to receive the displacement signal of laser displacement sensor, and do difference, enhanced processing, output control signal To programmable power supply, the changes of magnetic field of the voltage signal control coil (601) of 0~20V is converted to, is finally completed through several periods Put position control.

In hardware aspect, magnificent industrial personal computer IPC-610MB and general magnificent multi-function data acquisition card PCI-3363 are ground in selection.Industrial personal computer IPC-610MB's is configured to:CPU:E5300;Memory:4G;Hard disk:500G;CD-ROM drive:DVD.Capture card 3363 has 16 tunnel difference Input, highest 625ks/s sample rates, a/d resolution 18, input analog signal range -10V~10V;Export 4 tunnels simulation letter Number, maximum turnover rate 2MHz, DAC resolution ratio 16, output current maximum 50mA.

In terms of software interface, measurement and control program is write based on Labview, and generate observing and controlling installation file.Final software Friendly interface, perfect in shape and function, it includes parameter setting (title, the type of storage file), and data are shown, data readback, calibration The parts such as calibration.Wherein in parameter setting, title, the type of storage file, setting simulation, the sampling of digital channel can be set Frequency etc..

(1) micro- momentum feature obtains

Thrust rack system is considered as a black box, be input to system to be the response of thrust and system can lead to The shift in position that internal system does not exist together is crossed to observe.Each point of observation is moved for being input to the accurate of given thrust of system State response is extremely complex.In view of a nonlinear system, then have:

In above formula, x (t) is the data of point of observation.H (t) is unit impulse response, and f (t) is the thrust of input.Upper In formula, h (t) is only known, otherwise solve above formula without any method.Generally, in many cases, thrust rack is considered as There is the spring mass system of damping.If the spark rate of thruster is far longer than the intrinsic frequency of rack, acted in pulse Under, the equation of motion of certain point is on rack:

In above formula, ωn, ξ and meffRespectively effective natural frequency, damping factor and effective mass.

Above formula is reduced to the simple equation of momentum if not considering spring and damping:

For (2), if it is known that the effective mass of system, and obtain displacement and change with time, so that it may to measure simple venation The numerical value measured in a state of excitement.

The system self-correcting of test equipment can obtain effective mass, this can be measured by the counterweight of load known quality Under undamped state, the acceleration responsive (second dervative of displacement) of the pendulum obtains, and after measuring equivalent mass, utilizes (3) formula It can get momentum size.

(2) microthrust feature obtains

As shown in Figure 1 rocks system.Torque M=f (t) L caused by t at any time, active force f (t) (0≤t≤ t1), the damping movement under force equation that has rocked is:

Primary condition is

In above formula, t1For the continuous action time of active force f (t);ξ is to rock damping ratio, and J is torsional pendulum moment of inertia, ωn To rock non-damping vibration frequency.L is the distance between position and vertical rotating shaft.It is above-mentioned to rock parameter, reality can be passed through Standard inspection is fixed.

For the system of rocking, when for measuring constant thrust, the first-order partial derivative and second-order partial differential coefficient in formula (4) are equal It is 0, therefore, it is a simple elastic equation that above-mentioned equation, which is just degenerated,.I.e. after steady state force load, single pendulum is stable at a certain solid The fixed pendulum angle positions θ, power F and the relationship of pivot angle θ are at this time:

F*L=K* θ ≈ K*x/L (5)

Wherein L is effective pendulum arm length (point of force application is apart from axle center distance), and x is the displacement absolute value of point of force application, and K is The spring constant of flexible axle.Therefore, as long as measuring the swing displacement in stable state thrust, so that it may to obtain the accurate of thrust Numerical value.

(3) dynamic thrust measures

Static counterweight calibration can obtain the equivalent mass m of pendulumeff, adding for pendulum can be obtained using the second dervative of displacement Speed, then the two, which is multiplied, obtains the suffered resultant force of pendulum.This is the suffered external force of pendulum and the pendulum restoring force (reply of flexible axle with joint efforts Power) sum, it is known that the spring constant of pendulum and measure pivot angle, the restoring force of pendulum can be calculated, can thus be measured The suffered dynamic external force of pendulum.

Systematic survey sensitivity and accuracy evaluation:The torque coefficient for defining flexible axle is TSR, unit N.m/rad.It is right In stable state thrust measurement, it is assumed that the thrust of thruster is F, and the rotation center of position to flexible axle is L (pendulum arm length).It is then right Torque T at rotation center is:

T=FL (6)

Meanwhile rocking under the action of this moment, the angle of swing is θ.Wiggly table frame working condition is required in flexibility In the elastic range of axis, have:

FL=2TSR* θ (7)

(the reason of being multiplied by 2 is each 1 up and down because of rack two flexible axles of installation)

In the case where rocking swing angle θ~0, then have a θ ≈ sin θs, thrust point along thrust direction displacement S then It is equal to:

(8) can formula is used for assessing the system of rocking measure the important relationship of low thrust.

It is required that the maximum thrust measured is 1000mN, the linearly interval of flexible axle requires the maximum pendulum angle of pendulum to be less than 3 °, then The torque coefficient of flexible axle required for calculating:

It is calculated according to formula (9), we have selected the double-ended flexible axis product, model 6016-400, torque coefficient to be 1.85Nm/rad。

(1) Measurement Resolution is analyzed

At swing arm 250mm, the twin shaft wiggly table frame structure of torque coefficient 1.85N.m/rad, if the resolution ratio of displacement is 0.25um, then corresponding stable state thrust resolution ratio can be calculated by (7) formula:14.8uN.

(2) thrust measurement error analysis

Under these conditions, according to (7) Shi Ke get:If the measurement error of displacement is less than 10um (conservative estimation), thrust Measurement error 0.592mN.

(3) impulse measurement surface analysis

The maximum thrust of index request is 300mNs, load-bearing 15kg, and corresponding maximum slew rate is about 20mm/s.When displacement is differentiated When rate 0.25um, the accurate capture to speed may be implemented in the displacement measurement frequency of 80kHz or more, that is, realizes 300mNs momentums It is accurate to measure.

(4) impulse measurement precision analysis

The error of impulse measurement depends primarily on the measurement error of slew rate, and displacement sampling is depended primarily in practical operation The smooth number of point.When small impulse measurement, the sample frequency of 100kHz can provide the smooth of 1000 data points.The calculating of the 10ms In period, displacement error is mainly derived from vibration noise (damping) and displacement measurement errors when putting static.Rule of thumb, Pendulum displacement uncertainty caused by vibration noise is better than 0.1um;Displacement measurement errors are better than 0.25um, thus it is smooth after speed Measurement error should be 0.35um/10ms=0.035mm/s, and corresponding impulse measurement error is 0.53mNs.

The above is only presently preferred embodiments of the present invention, is not intended to limit the present invention in any form, it is every according to According to the technical spirit of the present invention to any simple modification, equivalent change and modification made by above example, still belong to the present invention The protection domain of technical solution.

Claims (10)

1. a kind of Micro-thrust test system comprising rack, displacement sensor, on-line proving component, damping system, computer are surveyed Control equipment;It is characterized in that:
The rack is to rock structure, including rack ontology, flexible axle, cantilever, counterweight and thruster fixing device, cantilever water Placing flat, middle part installation flexible axle are connect with rack ontology, and one end of cantilever places counterweight and other end connection thruster is fixed Device, microthruster are placed in thruster fixing device;
Institute's displacement sensors are reflective laser displacement sensor, and the beam signal sent out is anti-by the side surface of cantilever It penetrates, is recorded and handled by its internal CCD after return, to obtain the absolute distance of itself and cantilever side;
The on-line proving component hangs standard test weight using suspension, and it is elastic to control suspension by lifting platform, steady to generate State thrust demarcates Micro-thrust test system;
The damping system includes coil and iron core, and coil is fixed on the firm banking of rack, when iron core is transported relative to coil Electromagnetism suction and repulsion is generated when dynamic, is rocked to gradually static;
The computer measurement and control equipment includes connected high-frequency data capture card, industrial personal computer, display device;Reflective laser displacement The displacement data of sensor acquisition shows after being handled by industrial personal computer by display device;Industrial personal computer controls the height of lifting platform Degree, the pendulum thrust response under the load of measurement standard counterweight, realizes stable state thrust calibration;Industrial personal computer controls damping system to make to rock It is static.
2. Micro-thrust test system according to claim 1, it is characterised in that:The rack is that level rocks structure, is wrapped Include hold-down support, rotary support, flexible axle, cantilever, counterweight, limit transposition, thruster fixing device.
3. Micro-thrust test system according to claim 2, it is characterised in that:The flexible axle is model 6016-400 Flexible axle.
4. Micro-thrust test system according to claim 3, it is characterised in that:The reflective laser displacement sensor is The displacement sensor of model Panasonic HL-C203BE, measuring center distance are 30mm, and measurement range is ± 5mm, and displacement is differentiated Rate is 0.25um.
5. Micro-thrust test system according to claim 4, it is characterised in that:The damping system further includes programmable electricity Source is connect with coil.
6. Micro-thrust test system according to claim 5, it is characterised in that:The loop length 175mm, diameter 80mm, coil 400 are pricked, 12 ~ 20V of operating voltage, 5 Ω of actual measurement impedance;The core length 170mm, diameter 25mm;It is described to compile Journey power supply model RIGOL DP811A, maximum working voltage 40V, electric current 5A.
7. Micro-thrust test system according to claim 6, it is characterised in that:The on-line proving component drafts a mark Determine 196mN.
8. Micro-thrust test system according to claim 7, it is characterised in that:The lifting platform is vertically-mounted automatically controlled Translation stage, stroke 100mm, and fix translation stage respectively by two right angle fixed blocks and lift counterweight.
9. Micro-thrust test system according to claim 8, it is characterised in that:The industrial personal computer is to grind magnificent industrial personal computer IPC- 610MB, the capture card are general magnificent multi-function data acquisition card PCI-3363.
10. a kind of test method using Micro-thrust test system according to claim 1, it is characterised in that:Including with Lower step:
(1)Cantilever is mounted on by the flexible axle of two vertical direction on rack ontology;
(2)After installed thrust device, the level of cantilever is kept by controlling the weight of counterweight;
(3)Before test, it is static to make to rock that industrial personal computer controls damping system;
(4)The displacement data of reflective laser displacement sensor acquisition shows after being handled by industrial personal computer by display device;
(5)Industrial personal computer controls the height of lifting platform, and the pendulum thrust response under the load of measurement standard counterweight realizes that thrust is marked online It is fixed.
CN201610318356.9A 2016-05-13 2016-05-13 A kind of Micro-thrust test system and method CN105784237B (en)

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CN107844618B (en) * 2016-11-22 2021-01-01 中国人民解放军战略支援部队航天工程大学 Design method of torsional pendulum system for measuring thrust and impulse
CN107562691B (en) * 2017-08-14 2020-03-17 中国科学院力学研究所 Micro thrust dynamic test method based on least square method
CN107631817B (en) * 2017-08-14 2021-01-15 中国科学院力学研究所 micro-Newton micro-thrust test system and test method
CN108414127A (en) * 2018-02-01 2018-08-17 南京航空航天大学 Compensation Micromass cell culture torsion balance
CN108829946A (en) * 2018-05-29 2018-11-16 中国人民解放军战略支援部队航天工程大学 A kind of thrust calculation method based on dynamic compensation technology
CN108827512B (en) * 2018-06-22 2020-09-25 北京工业大学 Micro-thrust measuring device adopting silicon torsion spring
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CN110146208A (en) * 2019-06-06 2019-08-20 北京航空航天大学 A kind of device for measuring micro-thrust with on-line proving and locking function

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