CN117516803A - Rotational inertia integrated testing device and testing method - Google Patents
Rotational inertia integrated testing device and testing method Download PDFInfo
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- CN117516803A CN117516803A CN202311532260.9A CN202311532260A CN117516803A CN 117516803 A CN117516803 A CN 117516803A CN 202311532260 A CN202311532260 A CN 202311532260A CN 117516803 A CN117516803 A CN 117516803A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M1/00—Testing static or dynamic balance of machines or structures
- G01M1/14—Determining unbalance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
- G01G19/52—Weighing apparatus combined with other objects, e.g. furniture
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M1/00—Testing static or dynamic balance of machines or structures
- G01M1/12—Static balancing; Determining position of centre of gravity
- G01M1/122—Determining position of centre of gravity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M1/00—Testing static or dynamic balance of machines or structures
- G01M1/12—Static balancing; Determining position of centre of gravity
- G01M1/122—Determining position of centre of gravity
- G01M1/125—Determining position of centre of gravity of aircraft
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Abstract
The invention provides a rotational inertia integrated testing device and a testing method. The test device is characterized in that it comprises: the system comprises a carrying platform (1), an air bearing system (2), a supporting mechanism (3), a weighing system (4), a mass center adjusting system (5), a standard torsion bar set (6), a torsion bar testing system (7), an upper computer (9), a clamping mechanism (8), a supporting base (10) and a structural frame (11), wherein the standard torsion bar set (6) comprises a group of standard torsion bars (61) with different specifications, and when in use, one standard torsion bar (61) is selected to be vertically placed; the torsion bar testing system (7) is arranged on the outer side of a standard torsion bar (61) below the carrying platform (1), and is used for loading and releasing torque to the standard torsion bar (61) and transmitting measured data to the upper computer (9). The invention has adjustable measuring range, can realize the measurement of the moment of inertia of the spaceflight part component in multi-measuring range, and simultaneously gives consideration to the synchronous integrated measurement of the mass and the mass center.
Description
Technical Field
The invention relates to an inertia test technology in measurement test, in particular to a rotational inertia integrated test device and a test method.
Background
The quality characteristics are important physical quantities required for researching and controlling the orbit and the attitude of a flying body, and are measurement items required by various weapons such as projectile, rocket projectile, missile, nuclear warhead, torpedo, spacecraft such as carrier rockets, satellites and manned spacecraft and carrying equipment. The method provides important calculation basis for mechanical test, launching lift-off, on-orbit operation, recovery and the like of the spacecraft, and also provides necessary parameters for dynamic simulation, vibration and modal analysis, finite element calculation and the like of the system. The mass characteristic parameter comprises mass M and three-coordinate centroid position X c 、Y c 、Z c Moment of inertia I about three coordinate axes x 、I y 、I z And product of inertia I xy 、I yz 、I zx Etc. Wherein the moment of inertia (Rotational inertia) is a measure of the magnitude of inertia of the rigid body during rotation. It is related to the total mass, shape of the rigid body and the position of the axis of rotation. The accurate measurement of the moment of inertia has direct influence on the running state and the movement posture of the spacecraft in the space orbit, and has important significance on the design and control of the spacecraft; for space vehicles such as missiles, the precise control of the flight attitude, speed and acceleration of the space vehicles is facilitated.
The measuring method of the moment of inertia comprises a torsion pendulum method, a three-wire method, a single-wire pendulum method, a falling body method and the like. According to different supporting modes of the measuring platform, the method can be divided into an air bearing supporting mode and a mechanical bearing supporting mode. The most common means in the torsional pendulum method is to use a cylindrical section torsion bar made of metal or other materials as a torsional pendulum excitation element, and compared with torsional pendulum excitation by using a spring or other components, the torsional pendulum method has the advantages of good rigidity consistency and high accuracy. The single-axis air floating platform is an experimental device for measuring parameters such as rotational inertia, angular speed and the like of a large irregular object and is used for simulating single-axis motion of a spacecraft in a space microgravity environment. The air-float torsion pendulum method has the characteristics of high bearing, high measurement precision, small damping, proper price and the like.
At present, a common torsional pendulum method rotational inertia integrated testing device has the advantages that the measuring range is limited by the size structure of a torsional pendulum excitation element and the like, a wider measuring range cannot be realized, or a large-range measuring range is adopted to measure small-magnitude rotational inertia, and the linear consistency of the rigidity of a torsion bar under different angles cannot be ensured due to different torsional pendulum angles, so that the measuring precision can be greatly reduced. Due to the influence of the measuring range, units needing to perform high-precision rotational inertia tests in the national defense fields such as aerospace and the like often need to purchase a plurality of rotational inertia integrated test devices with different measuring ranges, so that the input cost is high, more use sites are occupied, and the use and maintenance cost is increased. Therefore, a rotary inertia integrated testing device which can be adjusted in measuring range, large in measuring range, high in testing precision and multipurpose needs to be designed.
After searching, 3 relatively close prior art technologies are found:
1) Journal literature: the patent discloses a mass, mass center and rotational inertia integrated test method and a test device, but the rotational inertia test adopts the method for acquiring rotational inertia values based on motor driving, measuring torque and angular acceleration parameters, which is different from the technical scheme of the patent, the angular acceleration parameters are difficult to acquire, and the measurement accuracy is lower.
2) Patent literature: the utility model provides a skin nano satellite mass, barycenter and moment of inertia integration measuring device, 201610606718.4, this document discloses a skin nano satellite mass, barycenter and moment of inertia integration measuring device, adopts motor drive, through measuring no-load and load state rotational speed change value and corresponding time value, obtains the moment of inertia value, has the difference with this patent technical scheme. The angular velocity parameters in each state need to be obtained for many times, and the actual measurement accuracy is low.
3) Patent literature: the patent application No. 201610227419 discloses a device and a method for measuring rotational inertia of an air bearing 2 by a supporting table type torsion pendulum method. The document discloses a device and a method for measuring rotational inertia of an air bearing 2 by a supporting table type torsion pendulum method, wherein a mass substitution method is adopted, a rotational inertia value is obtained through a swinging period measured by a light pipe, and the device and the method have the advantages of low measuring efficiency and narrow measuring range unlike the technical scheme of the patent.
Disclosure of Invention
Aiming at the characteristics of various structural dimensions, large parameter range span such as mass and moment of inertia and the like in the production test of model products in the aerospace field, the invention designs the multipurpose integrated test device and the test method which have the advantages of compact structure, adjustable range, large measurement range and high test precision and can simultaneously carry out the moment of inertia, mass and mass center test.
Specifically, the invention provides a rotational inertia integrated test device, which is characterized by comprising: the device comprises a carrying platform 1, an air bearing system 2, a supporting mechanism 3, a weighing system 4, a mass center adjusting system 5, a standard torsion bar set 6, a torsion bar testing system 7, an upper computer 9, a clamping mechanism 8, a supporting base 10 and a structural frame 11, wherein the carrying platform 1 is used for placing a tested piece; the supporting mechanism 3 is arranged at the upper end of a structural frame 11 arranged on the supporting base 10 and is used for jacking up and falling down the carrying platform 1 on the weighing system 4; the standard torsion bar group 6 comprises a group of standard torsion bars 61 with different specifications, when in use, one standard torsion bar 61 is selected to be vertically placed, one end of the bottom is fixed on the supporting base 10 through the clamping mechanism 8, and the other end is connected with the air bearing system 2; the air bearing system 2 performs air floatation opening and closing control through the upper computer 9, so that the movement limit of the standard torsion bar 61 is realized; the torsion bar testing system 7 is arranged on the outer side of a standard torsion bar 61 below the carrying platform 1, and is used for loading and releasing torque of the standard torsion bar 61 and transmitting measured data to the upper computer 9; the weighing system 4 is arranged on the carrying platform 1, weighs and transmits acquired signals to the upper computer 9; the mass center adjusting system 5 is arranged on the carrying platform 1 and used for balancing the mass center position of the measured piece, so that the mass center position is ensured to be positioned at the center position of the platform in a load state.
Further, each standard torsion bar 61 corresponds to a rotational inertia value in a different range, and each standard torsion bar 61 uses only a small torsion angle range when performing free torsion in the respective measurement range.
Further, the weighing system 4 includes a plurality of high-precision weighing sensors 40, a weighing sensor mounting seat 44, and a first acquisition unit 45, where the weighing sensors 40 are mounted and fixed below the carrying platform 1 through the weighing sensor mounting seat 44, and acquire acquisition signals through the first information acquisition unit 45 and then transmit the acquisition signals to the upper computer 9.
Further, the mass center adjusting system 5 includes a positioning guide rail 51, a standard mass block group 52, a distance measuring unit 53, and a second acquisition unit 54, where the positioning guide rail 51 is distributed on the object carrying platform 1 along the coordinate axis, the standard mass block group 52 includes a group of standard mass blocks with different masses, and the position of the standard mass block on the positioning guide rail 51 is adjusted to change the mass center position of the whole object carrying platform 1, the distance measuring unit 53 adopts a non-contact laser ranging system, the bottom of the distance measuring unit 53 is connected and fixed with the structural frame 11, the light path of the non-contact laser ranging system is consistent with the positioning guide rail 51 and the coordinate axis, the light path irradiates the standard mass block installed on the positioning guide rail 51 to obtain distance information of the distance measuring unit 53 relative to the standard mass block, and the distance information is transmitted to the upper computer 9 through the second acquisition unit 54.
Further, the torsion bar testing system 7 includes a torque measuring unit 71, an angle measuring unit 72, and a wobble frequency measuring unit 73, which measure torque, angle, and wobble frequency, respectively.
Further, the torsion bar testing system 7 further includes a torque loading and releasing mechanism 75, including a control unit 751, a driving loading unit 752, a clamping releasing mechanism 753, and a conditioning acquisition card 754, the standard torque sensor 74 is installed at the end of the driving loading unit 752, the clamping releasing mechanism 753 adopts a pneumatic ejector rod and a snap ring structure, the standard torque sensor 74 is connected with the standard torsion bar 61 through the snap ring during loading, the driving loading unit 752 uses a torque motor 7522 to cooperate with a motor driver 7521 to drive and load the standard torsion bar 61, the standard torsion bar 61 is twisted through driving the standard torque sensor 74, meanwhile, a pulse signal obtained through the circular grating angle encoder 721 is fed back to the motion controller 7511 and the motor driver 7521 to perform closed loop control, the control unit 751 performs feedback control on the rotation speed of the torque motor 7522 based on the motion controller 7511, the standard torque sensor 74 outputs a signal to the conditioning acquisition card and then sends the conditioning acquisition card 9, and the accurate loading of the standard torsion bar 61 is completed through monitoring of real-time torque and angle signals.
The invention also provides a rotational inertia integrated test method, which is characterized by comprising the following steps of:
step 1, selecting a standard torsion bar 61 matched with a measured piece rotational inertia predicted value, fixing the bottom end of the standard torsion bar 61 by using a clamping mechanism 8 of a testing device, and fixing the top end of the standard torsion bar 61 by using an air bearing 2;
step 2, after an initial moment is applied through torque loading of the torsion bar testing system 7, the rigidity coefficient of the standard torsion bar 61 is measured through calibration, then the standard torsion bar 61 is released to carry out micro torsion pendulum, the torsion pendulum frequency is measured through a pendulum frequency measuring unit in the torsion bar testing system 7, and a rotation inertia value of the testing device in an idle state is obtained through the upper computer 9;
step 3, fixing the measured object on the carrying platform 1 to perform mass center balance;
and 4, performing the rotational inertia test again to obtain a rotational inertia value under the load state, and obtaining the rotational inertia value of the measured piece through a corresponding calculation algorithm.
Further, in the step 2: when the torsion bar torsional pendulum system does small-angle free torsional pendulum motion, the vibration equation of the torsion bar torsional pendulum system is that
J 0 The moment of inertia in the idle state is K, the equivalent torsional rigidity of the torsion bar is constant in ideal conditions and elastic limit, theta is the torsional angle, C is the damping coefficient and t is time.
Definition of the definitionIs natural frequency of undamped vibration>For the system damping ratio, equation (1) is written as
In the case of ζ <1, i.e. weak damping, the solution of the differential equation is
Defined by damped vibration frequenciesT d And T 0 Vibration cycles with damping and undamped,f d and f 0 To have the torsional pendulum frequency without damping, respectively T d And T 0 The reciprocal of the moment of inertia is obtained by the calculation formula
f d Taking the average value of the torsional pendulum frequencies of N adjacent periods:
damping ratio xi adopts free attenuation method, takes the amplitude ratio of N adjacent periods to calculate damping ratio, and solves according to the following formula:
wherein: θ 1max And theta (N+1)max For the maximum value of the twist angle for the first and (N + 1) th cycles,
when the torsion bar testing system 7 applies initial torsion and initial torsion angle to the standard torsion bar 61, the torque variation value T is obtained in real time through the acquisition unit 45 and the upper computer 9 testing software i And a torsion angle change value θ i I=1, 2, … m, m is the number of sampling points, defined by the stiffness K of the torsion bar, resulting in a functional relation of the stiffness of the standard torsion bar 61:
thus, equation (4) is converted into:
the torsion bar rigidity, torsion pendulum frequency and damping ratio functional relation is obtained through the processing calculation of the torsion bar testing system 7 real-time torque and torsion angle parameter values and the upper computer 9 testing software, and finally the rotation inertia value in the no-load state is obtained.
Further, the step 3 includes: the carrying platform 1 is jacked up through the supporting mechanism 3, and then the measured piece is placed in the center of the platform. After being placed and fixed, the supporting mechanism 3 is adjusted to enable the carrying platform 1 to fall on the weighing system 4, and the mass m of the carrying platform 1 is obtained through the weighing system 4 1 Then can pass through the mass m in the idle state 0 Calculating the mass m of the measured piece t ＝m 1 -m 0 The method comprises the steps of acquiring the distance L (x, y) of the centroid position of a carrying platform 1 deviating from the origin of the coordinate center through a weighing system 4, selecting a proper standard mass block group 52 from a centroid adjusting system 5, placing the proper standard mass block group 52 on a positioning guide rail 51 with opposite deviation directions, adjusting the centroid by changing the position of the standard mass block group 52 on the guide rail, and monitoring the current position of the centroid in real time by using upper computer 9 testing software until the centroid is adjusted to the origin of the coordinate center, wherein the upper computer 9 testing software backtracks source information and distance through the standard mass block group 52From the relative position measured by the measuring unit 53, an additional moment of inertia of the proof mass set 52 is obtained:
wherein: m is m x And m y The total mass of the set of proof masses 52 attached to the positioning rail 51 on the X-axis and Y-axis of the coordinate system, respectively; l (L) x And L y The distances of the centroids of the additional proof mass sets 52 on the X-axis and Y-axis of the coordinate system, respectively, from the origin of the center of the coordinate system.
Further, the step 4 includes: the supporting mechanism 3 is loosened, the air bearing 2 is opened, the original torque and the torsion angle are applied to the standard torsion bar 61 through the torsion bar loading and releasing mechanism, and the torque change value T 'is obtained in real time through the acquisition unit 45 and the upper computer 9' i And a torsion angle variation value θ' i I=1, 2, … m, m is the sampling point number, and the torsion bar rigidity functional relation K ' (T ', θ ') is obtained through calculation, so as to obtain the rotation inertia value under load:
and finally, deducting the idle inertia and the additional inertia to obtain the rotational inertia of the measured piece:
J m ＝J′-J-ΔJ (11)。
the beneficial effects of the invention are that:
the invention has adjustable measuring range, can realize the measurement of the moment of inertia of the spaceflight part component in a multi-measuring range, and simultaneously takes into account the synchronous and integrated measurement of the mass and the mass center of the spaceflight part component. The standard torsion bar is simple and convenient to install and operate, convenient to assemble and disassemble and good in rigidity consistency, and measurement accuracy is greatly improved. The testing device directly participates in the moment of inertia measurement by utilizing the rigidity of the torsion bar, can replace the step of installing a standard rotor for self calibration before testing by the traditional moment of inertia integrated testing device, and greatly reduces the testing working hour.
In the preferred embodiment, the torsion bar testing system is integrated in the whole device, has a compact structure, acquires torque and torsion angles in real time, further improves the measurement accuracy, and simultaneously has a self-calibration function before testing the testing device.
In the preferred embodiment, the torsion frequency of the invention adopts a fixed angle time measurement method based on a grating encoder, uses a high-precision frequency standard card as a time standard, replaces the traditional time measurement method adopting a photoelectric switch, can eliminate errors introduced by the threshold width of a shading light-dark gate introduced in the measurement adopting the photoelectric switch, and further improves the measurement accuracy
In the preferred embodiment, the barycenter adjusting system can quickly balance the barycenter position of the measured piece, ensure that the barycenter position is positioned at the center position of the platform under the load state, avoid the moment of inertia introduced when the torsion bar performs free torsion, and improve the measurement accuracy.
In the preferred embodiment, the invention also adopts an upper computer measurement analysis system with a modularized bus structure, so that each parameter measurement value can be quickly obtained, meanwhile, the high-speed sampling rate can acquire the swing frequency measurement value and the torsion angle value in real time, and the rigidity value under each torsion frequency can be accurately acquired in real time through rigidity function relation calculation.
Drawings
FIG. 1 is a schematic diagram of a rotational inertia integrated test apparatus according to the present invention;
FIG. 2 is an overall frame of the moment of inertia integrated test apparatus of the present invention;
FIG. 3 is a schematic diagram of a weighing system of the present invention;
FIG. 4 is a schematic diagram of a centroid adjustment system according to the present invention;
FIG. 5 is a schematic diagram of a torsion bar testing system of the present invention;
FIG. 6 is a schematic diagram of a torque loading and release mechanism of the present invention.
Detailed Description
The invention provides a measuring range adjustable high-precision rotational inertia integrated testing device, and the specific embodiment of the invention is further described in detail below with reference to the accompanying drawings.
The national defense and military field, in particular to various product components in the aerospace satellite field, needs to test key parameters such as moment of inertia, mass center and the like on the ground. At present, a common torsional pendulum method rotational inertia integrated testing device cannot give consideration to the measurement range, the measurement precision and the measurement efficiency, so that a set of multi-range high-precision rotational inertia integrated testing device suitable for various measurement ranges, high measurement precision and high measurement efficiency is required to be designed, and meanwhile, mass and mass center integrated testing can be carried out.
1. Test device structure and frame
Fig. 1 is a schematic structural view of a moment of inertia integrated testing apparatus according to the present invention, and fig. 2 is a general frame of the moment of inertia integrated testing apparatus according to the present invention. As shown in fig. 1 and 2, the hardware part of the rotational inertia integrated testing device of the invention is composed of a carrying platform 1, an air bearing system 2, a supporting mechanism 3, a weighing system 4, a mass center adjusting system 5, a standard torsion bar group 6, a torsion bar testing system 7, an upper computer 9, a clamping mechanism 8, a supporting base 10, a structural frame 11 and the like.
The carrying platform 1 is used for placing a tested piece; the supporting mechanism 3 is arranged at the upper end of a structural frame 11 arranged on the supporting base 10 and is used for jacking up and falling down the carrying platform 1 on the weighing system 4; the standard torsion bar group 6 comprises a group of standard torsion bars 61 with different specifications, when in use, one standard torsion bar 61 is selected to be vertically placed, one end of the bottom is fixed on the supporting base 10 through the clamping mechanism 8, and the other end is connected with the air bearing system 2; the air bearing system 2 performs air floatation opening and closing control through the upper computer 9, so that the movement limit of the standard torsion bar 61 is realized; the torsion bar testing system 7 is arranged on the outer side of a standard torsion bar 61 below the carrying platform 1, and is used for loading and releasing torque of the standard torsion bar 61 and transmitting measured data to the upper computer 9; the weighing system 4 is arranged on the carrying platform 1, weighs and transmits acquired signals to the upper computer 9; the mass center adjusting system 5 is arranged on the carrying platform 1 and used for balancing the mass center position of the measured piece, so that the mass center position is ensured to be positioned at the center position of the platform in a load state.
During installation, firstly, a standard torsion bar 61 matched with the estimated value of the moment of inertia of the tested piece is selected, the bottom end of the standard torsion bar 61 is fixed by using a clamping mechanism 8 of the testing device, and the top end of the standard torsion bar 61 is fixed by using an air bearing 2. When the measuring range needs to be changed, the carrying platform 1 and the air bearing 2 can be disassembled, the clamping mechanism 8 is loosened, the original standard torsion bar 61 is taken down, the original standard torsion bar 61 is replaced by the standard torsion bar 61 with different specifications, and then the clamping installation is carried out again.
The standard torsion bar group 6 subdivides the reasonable range, each standard torsion bar 61 corresponds to the rotation inertia value of different measuring ranges, and each standard torsion bar 61 only uses a small torsion angle range when performing free torsion in the respective measuring range, so that the rigidity consistency of the standard torsion bar 61 is good, and the measuring precision is greatly improved. The maximum moment of inertia measurement can be from 10 1 kg·m 2 To 10 4 kg·m 2 。
As described above, the standard torsion bar 61 is clamped by the bottom end fixing, and the top end bearing is fastened by the mounting method, so that the operation is simple and the dismounting is convenient. At each use, a suitable standard torsion bar 61 is selected. By adopting a design scheme of a group of standard torsion bars 61, the standard torsion bars 61 with proper specifications can be selected corresponding to different moment of inertia measurement ranges for different measured objects.
Fig. 3 is a schematic view of a weighing system of the present invention. As shown in fig. 3, the weighing system 4 of the present invention mainly comprises a plurality of high-precision weighing sensors 40, a weighing sensor mounting base 44, a first acquisition unit 45, and corresponding test software installed on the upper computer 9. The weighing sensor 40 is fixedly arranged below the carrying platform 1 through a weighing sensor mounting seat 44, acquires acquisition signals through an information acquisition unit I45 and transmits the acquisition signals to the upper computer 9. In one embodiment, the load cell 40 includes 3 high-precision load cells, namely, a first high-precision load cell 41, a second high-precision load cell 42, and a third high-precision load cell 43. The three sensor positions are shown in fig. 3.
Fig. 4 is a schematic diagram of a centroid adjustment system in accordance with the present invention. As shown in fig. 4, the mass center adjusting system 5 of the present invention is composed of a positioning guide rail 51, a standard mass block group 52, a distance measuring unit 53, a second acquisition unit 54, and corresponding test software installed on the upper computer 9. Proof mass set 52 includes a set of proof masses of different masses. Each standard mass block in the standard mass block group 52 adopts a disc-shaped structure, the mass m and the moment of inertia deltaj of the standard mass block are traced through a metering technical mechanism, and the mass and moment of inertia information of the standard mass block are written into the test software of the upper computer 9 for resolving. When the standard mass block is used each time, a proper standard mass block is selected, and the standard mass block which is not more than 5-10% of the mass of the measured piece is preferably selected. The positioning guide rails 51 are distributed on the carrying platform 1 along the coordinate axis and have the function of locking the standard mass block. The proof mass may slide or lock along the positioning rail 51. By adjusting the position of the proof mass on the positioning rail 51, the centroid position of the entire load platform 1 is changed.
The distance measuring unit 53 is composed of a non-contact laser ranging system, and the bottom is fixedly connected with the structural frame 11 of the rotational inertia integrated testing device through a mounting mechanism. The light path of the non-contact laser ranging system is consistent with the positioning guide rail 51 and the axis of the coordinate system, the light path irradiates the standard mass block arranged on the positioning guide rail 51 to obtain the distance information of the distance measuring unit 53 relative to the standard mass block, and then the distance information is converted into the distance value relative to the origin of the coordinate center through the testing software of the upper computer 9 and the coordinate information of the carrying platform 1.
The barycenter adjusting system 5 can quickly balance the barycenter position of the measured piece, ensure that the barycenter position is positioned at the center position of the platform in a load state, avoid inertia moment introduced when the torsion bar performs free torsion, and improve measurement accuracy. The components such as the standard mass block group 52 and the like participating in balancing acquire additional rotation inertia values in real time through the acquisition unit II 54, data storage is carried out in the upper computer 9, and finally the rotation inertia values measured under the load are corrected through the test software of the upper computer 9, so that accurate measurement values are quickly obtained.
FIG. 5 is a schematic diagram of a torsion bar testing system of the present invention. The torsion bar test system 7 has the functions of torque loading, high-precision measurement of torsion bar rigidity, initial torque loading and releasing before rotational inertia test, torsion pendulum frequency measurement and the like. As shown in fig. 5, the torsion bar testing system 7 of the present invention is composed of a torque measuring unit 71, an angle measuring unit 72, a wobble frequency measuring unit 73, a test sensor mounting seat 74, a torque loading and releasing mechanism 75 and corresponding test software installed on the upper computer 9. The torque measuring unit 71 consists of a standard torque sensor 711 and a conditioning and collecting card 712, and is used for real-time measurement of torsion bar initial torque and closed-loop control of torque loading; the angle measuring unit 72 consists of a circular grating angle encoder 721 and an encoder acquisition card 722 and is used for measuring the initial angle of the torsion bar and performing closed-loop control on torque loading; the wobble frequency measuring unit 73 is composed of a circular grating angle encoder 721 and a digital frequency meter 732, a pulse signal of the circular grating angle encoder 721 in the process of twisting is obtained through the high-precision digital frequency meter 732, and a twist frequency value is obtained through calculation through test software of the upper computer 9.
Thereby, the torsion bar testing system 7 is integrated in the whole device, and the structure is compact.
The torsion bar testing system 7 can acquire a one-to-one correspondence relation between the torsion and the torsion angle in the whole loading process of the standard torsion bar 61 from the initial position until the preset torsion angle is reached, and can calculate a functional relation of the torsion bar rigidity, so that the measurement accuracy is further improved, and meanwhile, the torsion bar testing system has a self-calibration function before testing the testing device.
The torsion bar is subjected to pure torque load as T, and the corresponding rotation angle of the free end of the torsion bar isThe stiffness K of the torsion bar is defined as +.>The stiffness value can be obtained by torque and rotation angle.
The testing device directly participates in the moment of inertia measurement by utilizing the rigidity of the torsion bar, can replace the step of installing a standard rotor for self calibration before testing by the traditional moment of inertia integrated testing device, and greatly reduces the testing working hour.
In addition, the wobble frequency employs a fixed angle timing method based on a grating encoder, a high-precision frequency standard card is used as a time standard, and the wobble frequency measuring unit 73 in fig. 2 is constructed by using the high-precision frequency standard card.
The method replaces the traditional time measurement method adopting a photoelectric switch, can eliminate errors introduced by the width of the threshold of the shading light-dark gate which is introduced in the measurement adopting the photoelectric switch, and further improves the measurement accuracy.
FIG. 6 is a schematic diagram of a torque loading and release mechanism of the present invention. As shown in fig. 6, the torque loading and releasing mechanism 75 of the present invention is composed of a control unit 751 (transmission unit), a drive loading unit 752 (servo loading unit), a clamp releasing mechanism 753, a conditioning acquisition card 754, and the like. A standard torque sensor 74 is mounted at the end of the drive loading unit 752. The control unit 751 includes a motion controller 7511 and an upper computer 9 and associated control software. The drive loading unit 752 includes a torque motor 7522 and a motor driver 7521. The clamping release mechanism 753 adopts a pneumatic ejector rod and snap ring structure, when loading, the standard torque sensor 74 is connected with the standard torsion bar 61 through the snap ring, and after initial torque loading is completed, the snap ring structure is released through controlling the pneumatic ejector rod, so that the function of quick release is achieved.
In the loading process, the driving loading unit 752 is stable in transmission, the torque motor 7522 with large driving loading force is matched with the motor driver 7521 to carry out driving loading, the standard torsion bar 61 is twisted by driving the standard torsion bar sensor 74 arranged at the tail end of the driving loading unit 752, meanwhile, the pulse signal obtained by the circular grating angle encoder 721 is subjected to closed-loop control, and the control unit 751 carries out feedback control on the rotating speed of the torque motor 7522 based on the full-digital closed-loop motion controller 7511 of the DSP to realize accurate control on the loading speed. The standard torque sensor 74 outputs a signal to the conditioning acquisition card 754 and then sends the signal to the host computer 9, and accurate loading of the standard torsion bar 61 is completed by monitoring the real-time torque and angle signals.
The upper computer 9 has the functions of controlling acquisition measurement and data analysis processing, and comprises data analysis test software. The host computer 9 is a core part of the initial device. The device has the following functions:
(1) For air bearing system 2
The air bearing system 2 is controlled to be opened and closed by the upper computer 9, and the air bearing system 2 realizes the movement limit of the standard torsion bar 61.
(2) For the weighing system 4
The upper computer 9 can read the mass value of the high-precision weighing sensor in real time, and calculate the mass and the mass center position. The mass and the mass center of the whole carrying platform 1 in the no-load and load state are obtained through the high-precision weighing sensor 40 and the acquisition unit 45 in the weighing system 4, and the mass center position during mass center adjustment balance can be monitored in real time by the upper computer 9, so that the final adjustment of the mass center adjustment system 5 is facilitated.
(3) For centroid adjustment system 5
The upper computer 9 software has a moment of inertia resolving function, and obtains the additional moment of inertia added by the standard mass block group 52 through the mass center adjusting system 5. The upper computer 9 can read the distance value of the distance measuring unit 53 in real time, and calculate an additional rotational inertia value according to the traceability information of the additional standard mass block group 52.
(4) For standard torsion bar set 6
The upper computer 9 software has the function of fitting the rigidity value function of the standard torsion bar 61, and can calculate the functional relation of the torsion bar rigidity according to the real-time torque and torsion angle value.
(5) For torsion bar testing system 7
The torsion bar test system 7 performs initial torque loading and release control through the upper computer 9. The upper computer 9 can read the torque value of the standard torque sensor 74; the angle value of the high-precision circular grating encoder 721 can be read in real time, and closed-loop control can be performed on the motor according to the grating angle value; the pulse signal of the digital frequency meter 732 can be read in real time, and the torsional frequency value can be calculated from the pulse signal. The torsion bar testing system 7 comprises a torsion bar rigidity measuring unit, an angle measuring unit and a swinging frequency measuring unit, wherein the torsion bar rigidity measuring unit, the angle measuring unit and the swinging frequency measuring unit are respectively used for obtaining a torsion bar rigidity calibration moment, a torsion angle value and a periodic pulse measuring value during torsion swinging, the torsion bar rigidity value and the torsion swinging frequency value are obtained through analysis and processing of test software of the upper computer 9, and finally, a rotation inertia value of a tested piece is obtained through a corresponding algorithm. The upper computer 9 software has a torque protection mode, when the motor moves to a certain position, the torque value reaches a target value (self-determination), the motor stops, and the motor is locked;
(6) Others
Has the functions of emergency stop and alarm under the condition of exceeding the measuring range. The upper computer 9 measurement analysis system adopting the modularized bus structure can rapidly acquire each parameter measurement value. Meanwhile, the high-speed sampling rate can acquire the swing frequency measured value and the torsion angle value in real time, and the rigidity value under each torsion frequency can be accurately acquired in real time through rigidity function relation calculation.
2. Test device principle and test method
2.1 rotational inertia value in no-load condition
The stiffness coefficient of the standard torsion bar 61 is measured by calibration after an initial moment is applied by the torque loading of the torsion bar testing system 7. Then the standard torsion bar 61 is released to make it perform a slight torsion pendulum, the torsion pendulum frequency is measured by a pendulum frequency measuring unit in the torsion bar test system 7, and the rotational inertia value of the test device in the idle state is obtained by the upper computer 9.
Specifically, with the torque loading release mechanism in the torsion bar testing system 7, the initial torque and the initial torsion angle are applied to the standard torsion bar 61 so as to freely oscillate under the restoring force of the torsion bar. When the torsion bar does small-angle free torsion pendulum motion, the restoring force generated by the torsion bar is directly proportional to the deformation of the torsion bar and is converted into the torque M relative to the rotation center 1 -kθ, where K is the torsion bar equivalent torsional stiffness, constant in ideal case and elastic limit, θ is the torsion angle; air resistance being proportional to rotational angular velocity in torsional pendulum movement, i.eWherein C is the damping coefficient. Set J 0 The moment of inertia in the idle state is given by the vibration equation of the torsion pendulum system
Definition of the definitionIs natural frequency of undamped vibration>For the system damping ratio, the original equation can be written as
In the case of ζ <1, i.e. weak damping, the solution of the differential equation is
Defined by damped vibration frequenciesTd and T 0 Vibration cycles with damping and undamped,fd and f 0 To have the torsional pendulum frequency without damping, td and T respectively 0 Is the inverse of (c). The calculation formula for the moment of inertia is thus obtained as
fd takes the mean of the wobble frequency for N adjacent cycles:
damping ratio xi adopts free attenuation method, takes the amplitude ratio of N adjacent periods to calculate damping ratio, and solves according to the following formula:
wherein: θ 1max And theta (N+1)max Is the maximum value of the torsion angle for the first and (n+1) th cycles.
When the torsion bar testing system 7 applies initial torsion and initial torsion angle to the standard torsion bar 61, the torque variation value T is obtained in real time through the acquisition unit 45 and the upper computer 9 testing software i And a torsion angle change value θ i (i=1, 2, … m, m is the number of sampling points). The functional relation of the stiffness of the standard torsion bar 61 is defined by the stiffness K of the torsion bar:
thus, equation (4) can be converted into:
the torsion bar rigidity, torsion pendulum frequency and damping ratio functional relation is obtained through the processing calculation of the torsion bar testing system 7 real-time torque and torsion angle parameter values and the upper computer 9 testing software, and finally the rotation inertia value in the no-load state is obtained.
2.2 method for measuring moment of inertia in load state
Then, the measured object is fixed on the object carrying platform 1, the moment of inertia test is carried out again after the mass center is balanced, the moment of inertia value under the load state is obtained, and the moment of inertia value of the measured object is obtained through a corresponding calculation algorithm.
Specifically, after the no-load test is completed, the carrying platform 1 is jacked up by the supporting mechanism 3, and then the tested piece is placed in the center of the platform. After being placed and fixed, the supporting mechanism 3 is adjusted so that the carrying platform 1 falls on the weighing system 4. Acquiring the mass m of the load platform 1 by means of the weighing system 4 1 Then can pass through the mass m in the idle state 0 Calculating the mass m of the measured piece t ＝m 1 -m 0 。
The distance L (x, y) of the centroid position of the carrying platform 1 from the origin of the coordinate center is obtained through the weighing system 4, a proper standard mass block group 52 is selected in the centroid adjusting system 5 to be placed on a positioning guide rail 51 with opposite deviation directions, and the centroid is adjusted by changing the position of the standard mass block group 52 on the guide rail. The upper computer 9 test software monitors the current position of the centroid in real time until the centroid is adjusted to the origin of the coordinate center. The upper computer 9 test software obtains the additional moment of inertia of the standard mass block group 52 through the tracing information of the standard mass block group 52 and the relative position measured by the distance measuring unit 53:
wherein: m is m x And m y The total mass of the set of proof masses 52 attached to the positioning rail 51 on the X-axis and Y-axis of the coordinate system, respectively; l (L) x And L y The distances of the centroids of the additional proof mass sets 52 on the X-axis and Y-axis of the coordinate system, respectively, from the origin of the center of the coordinate system.
After the centroid adjustment is completed, the supporting mechanism 3 is loosened, the air bearing 2 is opened, the torsion bar loading and releasing mechanism is used for applying initial torque and torsion angle to the standard torsion bar 61, and the torque change value T 'is obtained in real time through the acquisition unit 45 and the upper computer 9' i And a torsion angle variation value θ' i (i=1, 2, … m, m is the number of sampling points), and the torsion bar rigidity functional relation K ' (T ', θ ') is obtained through calculation, so that the rotational inertia value under load can be obtained:
and finally, deducting the idle inertia and the additional inertia to obtain the rotational inertia of the measured piece:
J m ＝J′-J-ΔJ (11)
when the measuring range needs to be changed, the carrying platform 1 and the air bearing 2 can be disassembled, the clamping mechanism 8 is loosened, the original standard torsion bar 61 is taken down to be replaced by the standard torsion bar 61 with different specifications, then clamping and installation are carried out again, and the operation is carried out according to the step 6.2, so that the high-precision measurement of the moment of inertia under different measuring ranges can be realized.
2.3 workflow of weighing System
The supporting mechanism 3 is released so that the carrying platform 1 with the tested piece placed on the carrying platform falls onto the pressing heads of all weighing sensors of the weighing system 4, and the acquisition signals of all weighing sensors are obtained through the acquisition unit 45. And the mass and mass center deviation position of the object carrying platform 1 with the object to be tested is obtained based on a corresponding calculation algorithm by acquiring the signal value and the distance information of the relative coordinate center of the sensor by using corresponding test software in the upper computer 9.
L 1 、L 2 、H 2 、H 3 The vertical distance of the 3 sensors from the coordinate axes, respectively.
The acquisition unit 45 acquires the measured values m of 3 weighing sensors 1 ，m 2 ，m 3 The mass m and the x-direction mass center x of the whole carrying platform 1 can be obtained according to the following formula c Y-direction centroid y c ：
m＝m 1 +m 2 +m 3 (12)
2.4 centroid adjustment workflow
Firstly, according to the deviation position of the mass center of the measured piece obtained by the weighing system 4, the proper standard mass blocks in the standard mass block group 52 are selected to be placed on the corresponding positioning guide rails 51, and then the mass center is balanced to the center of the platform by moving the positions of the standard mass blocks on the guide rails.
When the position is adjusted, the distance measuring unit 53 adopts a laser non-contact measuring method to obtain the position information of the standard mass block in real time and feeds back the position information to the upper computer 9, and the mass center position changed due to the position change of the standard mass block is obtained through real-time calculation by the testing software of the upper computer 9, so that the relative position of the mass center is monitored in real time, and the mass center balance is completed until the mass center position is positioned at the center position of the coordinate system, and the standard mass block is locked and fixed.
The rotational inertia value added to the proof mass set 52 can be obtained according to equation (9) described above.
After the mass center balance is completed, the upper computer 9 obtains the rotational inertia value added to the standard mass block group 52 and the position change of the standard mass block group through test software, and the rotational inertia value is added to the whole carrying platform 1.
In the whole device, all measurement steps are uniformly controlled and displayed by a host computer 9, and parameter input and measured calculation are realized through test software written by the host computer 9.
It should be noted that the foregoing is merely illustrative and explanatory of the invention, and that any modifications and substitutions of the invention will be apparent to those skilled in the art, and are intended to be within the scope of the invention.
Claims (10)
1. A moment of inertia integrated test apparatus, comprising: the device comprises a carrying platform (1), an air bearing system (2), a supporting mechanism (3), a weighing system (4), a mass center adjusting system (5), a standard torsion bar set (6), a torsion bar testing system (7), an upper computer (9), a clamping mechanism (8), a supporting base (10) and a structural frame (11), wherein the carrying platform (1) is used for placing a tested piece; the supporting mechanism (3) is arranged at the upper end of a structural frame (11) arranged on the supporting base (10) and is used for jacking up and falling down the carrying platform (1) on the weighing system (4); the standard torsion bar group (6) comprises a group of standard torsion bars (61) with different specifications, when the standard torsion bar is used, one standard torsion bar (61) is selected to be vertically placed, one end of the bottom is fixed on the supporting base (10) through the clamping mechanism (8), and the other end is connected with the air bearing system (2); the air bearing system (2) performs air floatation opening and closing control through the upper computer (9) to realize movement limit of the standard torsion bar (61); the torsion bar testing system (7) is arranged on the outer side of a standard torsion bar (61) below the carrying platform (1), and is used for loading and releasing torque of the standard torsion bar (61) and transmitting measured data to the upper computer (9); the weighing system (4) is arranged on the carrying platform (1), and is used for weighing and transmitting acquired signals to the upper computer (9); the mass center adjusting system (5) is arranged on the carrying platform (1) and used for balancing the mass center position of the measured piece, so that the mass center position is ensured to be positioned at the center position of the platform under the load state.
2. A moment of inertia integrated testing apparatus according to claim 1, wherein each standard torsion bar (61) corresponds to a respective moment of inertia value of a different range of range, and each standard torsion bar (61) uses only a small range of torsion angles when performing free torsion in the respective measuring range.
3. The integrated moment of inertia testing apparatus of claim 1, wherein the weighing system (4) comprises a plurality of high-precision weighing sensors (40), a weighing sensor mounting seat (44) and a first acquisition unit (45), the weighing sensors (40) are mounted and fixed below the carrying platform (1) through the weighing sensor mounting seat (44), and the first acquisition unit (45) acquires acquisition signals and transmits the acquisition signals to the upper computer (9).
4. The rotational inertia integrated testing device according to claim 1, wherein the mass center adjusting system (5) comprises a positioning guide rail (51), a standard mass block group (52), a distance measuring unit (53) and a second acquisition unit (54), the positioning guide rail (51) is distributed on the carrying platform (1) along a coordinate axis, the standard mass block group (52) comprises a group of standard mass blocks with different masses, the position of the standard mass blocks on the positioning guide rail (51) is adjusted so as to change the mass center position of the whole carrying platform (1), the distance measuring unit (53) adopts a non-contact laser ranging system, the bottom of the distance measuring unit is fixedly connected with the structural frame (11), a light path of the non-contact laser ranging system is consistent with the positioning guide rail (51) and the coordinate system axis, the light path irradiates the standard mass blocks mounted on the positioning guide rail (51) to obtain distance information of the distance measuring unit (53) relative to the standard mass blocks, and the distance information of the distance measuring unit is transmitted to the upper computer (9) through the second acquisition unit (54).
5. The rotational inertia integrated test apparatus according to claim 1, wherein the torsion bar test system (7) includes a torque measurement unit (71), an angle measurement unit (72), a wobble frequency measurement unit (73) that measure torque, angle, and wobble frequency, respectively.
6. The integrated moment of inertia testing device according to claim 1, wherein the torsion bar testing system (7) further comprises a torque loading and releasing mechanism (75), and comprises a control unit (751), a driving loading unit (752), a clamping releasing mechanism (753) and a conditioning acquisition card (754), wherein a standard torque sensor (74) is installed at the tail end of the driving loading unit (752), the clamping releasing mechanism (753) adopts a pneumatic ejector rod and a clamping ring structure, the standard torque sensor (74) is connected with the standard torsion bar (61) through the clamping ring during loading, the driving loading unit (752) adopts a torque motor (7522) to carry out driving loading in cooperation with a motor driver (7521), the standard torsion bar (61) is twisted through driving the standard torque sensor (74), meanwhile, a pulse signal feedback motion controller (7511) obtained through a circular grating angle encoder (721) and the motor driver (7511) are subjected to closed-loop control, the control of the moment motor (751) is realized through feedback control on the rotating speed of the torque motor (7512) based on the motion controller (751), and then the accurate real-time monitoring of the torque acquisition signal (754) is carried out on the accurate real-time monitoring of the torque acquisition signal (61).
7. A moment of inertia integrated test method, characterized in that it uses the moment of inertia integrated test apparatus according to any one of claims 1 to 6, comprising the steps of:
step 1, selecting a standard torsion bar (61) matched with a rotational inertia predicted value of a measured piece, fixing the bottom end of the standard torsion bar by using a clamping mechanism (8) of a testing device, and fixing the top end of the standard torsion bar (61) by using an air bearing (2);
step 2, after an initial moment is applied through torque loading of a torsion bar testing system (7), the rigidity coefficient of a standard torsion bar (61) is measured through calibration, then the standard torsion bar (61) is released to enable the standard torsion bar to perform micro torsion, the torsion frequency is measured through a torsion frequency measuring unit in the torsion bar testing system (7), and a rotation inertia value of a testing device in an idle state is obtained through an upper computer (9);
step 3, fixing the measured object on the carrying platform (1) to perform mass center balance;
and 4, performing the rotational inertia test again to obtain a rotational inertia value under the load state, and obtaining the rotational inertia value of the measured piece through a corresponding calculation algorithm.
8. The method for integrated moment of inertia test as set forth in claim 7, wherein in step 2: when the torsion bar torsional pendulum system does small-angle free torsional pendulum motion, the vibration equation of the torsion bar torsional pendulum system is that
J 0 The moment of inertia under no-load condition, K is the equivalent torsional rigidity of torsion bar, it is constant in ideal condition and elastic limit, θ is torsion angle, C is damping coefficient, t is time,
definition of the definitionIs natural frequency of undamped vibration>For the system damping ratio, equation (1) is written as
In the case of ζ <1, i.e. weak damping, the solution of the differential equation is
Defined by damped vibration frequenciesT d And T 0 Vibration cycles with damping and undamped,f d and f 0 To have the torsional pendulum frequency without damping, respectively T d And T 0 The reciprocal of the moment of inertia is obtained by the calculation formula
f d Taking the average value of the torsional pendulum frequencies of N adjacent periods:
damping ratio xi adopts free attenuation method, takes the amplitude ratio of N adjacent periods to calculate damping ratio, and solves according to the following formula:
wherein: θ 1max And theta (N+1)max For the first and N +1 cycle of the maximum value of the twist angle,
when the torsion bar testing system (7) applies initial torque and initial torsion angle to the standard torsion bar (61), the torque change value T is obtained in real time through the acquisition unit (45) and the upper computer (9) testing software i And a torsion angle change value θ i I=1, 2, … m, m is the number of sampling points, defined by the stiffness K of the torsion bar, resulting in a standard torsion bar (61) stiffnessIs a functional relation of (a):
thus, equation (4) is converted into:
the torsion bar rigidity, torsion pendulum frequency and damping ratio functional relation is obtained through processing calculation of torsion bar testing system (7) torque and torsion angle parameter values obtained in real time through upper computer (9) testing software, and finally the rotation inertia value in the no-load state is obtained.
9. The moment of inertia integrated testing method of claim 8, wherein step 3 comprises: the support mechanism (3) is used for jacking the carrying platform (1), then the measured piece is placed in the center of the platform, after the measured piece is placed and fixed, the support mechanism (3) is adjusted to enable the carrying platform (1) to fall on the weighing system (4), and the mass m of the carrying platform (1) is obtained through the weighing system (4) 1 Then can pass through the mass m in the idle state 0 Calculating the mass m of the measured piece t ＝m 1 -m 0 The method comprises the steps of acquiring a distance L (x, y) of a centroid position of a carrying platform (1) deviating from a coordinate center origin through a weighing system (4), selecting a proper standard mass block group (52) from a centroid adjusting system (5), placing the proper standard mass block group (52) on a positioning guide rail (51) with opposite deviation directions, adjusting the centroid by changing the position of the standard mass block group (52) on the guide rail, monitoring the current position of the centroid in real time by upper computer (9) testing software until the centroid is adjusted to the coordinate center origin, and acquiring the additional rotational inertia of the standard mass block group (52) by the upper computer (9) testing software according to the tracing information of the standard mass block group (52) and the relative position measured by a distance measuring unit (53).
Wherein: m is m x And m y The total mass of the standard mass block group (52) which is respectively added to the positioning guide rail (51) on the X axis and the Y axis of the coordinate system; l (L) x And L y The distances of the centroids of the additional proof mass sets (52) on the X-axis and Y-axis of the coordinate system, respectively, from the origin of the center of the coordinate system.
10. The moment of inertia integrated testing method of claim 9, wherein step 4 comprises: the supporting mechanism (3) is loosened, the air bearing (2) is opened, initial torque and torsion angle are applied to the standard torsion bar (61) through the torsion bar loading and releasing mechanism, and the torque change value T 'is obtained in real time through the acquisition unit (45) and the upper computer (9)' i And a torsion angle variation value θ' i I=1, 2, … m, m is the sampling point number, and the torsion bar rigidity functional relation K ' (T ', θ ') is obtained through calculation, so as to obtain the rotation inertia value under load:
and finally, deducting the idle inertia and the additional inertia to obtain the rotational inertia of the measured piece:
J m ＝J′-J-ΔJ (11)。
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