CN108444706A - Multi-parameter mass property testboard based on spherical surface air-bearing - Google Patents

Abstract

The invention discloses a multi-parameter quality characteristic test bench based on a spherical air bearing. The test bench includes four parts: a ball air bearing assembly, a pendulum assembly, a pendulum assembly and a pendulum return assembly. The present invention has The four parts of the specific structure, as well as various forms of air bearing lubrication methods, effectively control the influence of external damping on the test results, greatly improve the test capability and test accuracy of the test equipment, and at the same time minimize the number of test fixtures, Improve test efficiency and test safety and reliability.

Description

Multi-parameter Quality Characteristic Test Bench Based on Spherical Air Bearing

technical field

The invention relates to a device for testing the quality characteristics of a spacecraft whole star, spacecraft parts and spacecraft sub-systems and a method for using the same, belonging to the technical field of spacecraft assembly testing. In addition, the present invention can also be used in the fields of complete vehicles and parts of vehicles, trains and other transportation tools, aviation, weapons and the like to complete the quality characteristic test of related products.

Background technique

At this stage, the spacecraft mass characteristic test equipment is composed of a center of mass moment of inertia comprehensive test bench and a linear three-coordinate conversion machine. Among them, the center-of-mass moment of inertia comprehensive test bench is installed once, which can measure the mass of the spacecraft, 2 parameters of the lateral center of mass and 1 parameter of the moment of inertia of the plumb axis.

The linear three-coordinate conversion machine is a general-purpose chemical equipment for spacecraft quality characteristic testing, which realizes the function of automatic conversion of the positional relationship between the spacecraft coordinate system and the test coordinate system.

The three-coordinate conversion machine testing technology is to use the center of mass moment of inertia comprehensive test bench and the linear three-coordinate conversion machine in combination, so that the spacecraft only needs to be installed and positioned once, and the coordinate system of the spacecraft and the test coordinate system are automatically transformed by the three-coordinate conversion machine. It can measure all quality characteristic parameters such as mass, center of mass, moment of inertia, product of inertia, etc.

However, the three-coordinate transformation machine testing technology still has big defects. One is: It is necessary to design and manufacture a three-coordinate transformation machine that is equivalent to the weight of the product to be measured. Therefore, the bearing capacity and test accuracy of the test bench will be seriously affected by the test tooling; the second is: with the development of large-scale spacecraft, there are huge technical difficulties in developing a larger three-coordinate conversion machine. The third is: the measurement of the product of inertia is an indirect measurement, and the test accuracy is not high compared with the dynamic balancing machine method;

Contents of the invention

The technical problem solved by the present invention is to provide a testing device that can realize the integration of center of mass, moment of inertia and product of inertia. The spacecraft can be installed and positioned once on the test bench of the present invention through simple horizontal tooling, and all quality characteristic parameters in all directions of the spacecraft can be measured.

The present invention has adopted following technical scheme:

1. Multi-parameter spherical air bearing quality characteristic test bench, including ball air bearing assembly, pendulum rod assembly, pendulum assembly and two sets of pendulum return components respectively installed on the left and right sides of the pendulum assembly, of which:

Ball air bearing assembly includes air float ball head, air float ball socket, base frame; Ball segment structure, the position of the center of the ball is higher than the docking plane, and compressed air is passed between the segment and the air-floating ball socket to generate an air film, and the air-floating ball head performs undamped movement in the air-floating ball socket; the base frame is The cubic frame structure is the installation basis of the entire equipment, and the lower part of the air float ball socket and the upper part of the base frame are rigidly connected by bolts;

The swing rod assembly is composed of a support sleeve, a torsion bar spring, a torsion motion drive mechanism, a torsion grating scale, a torsion drive motor, a flat air bearing lower plate, and a rotating motor. The support sleeve is a hollow tubular structure, and the upper part and the bottom of the air float ball head pass through The bolts are rigidly connected, the lower part is rigidly connected with the plane air bearing lower plate through bolts, the torsion bar spring runs through the inside of the support sleeve, the upper part of the torsion bar spring is rigidly connected with the bottom of the air flotation ball head through the torsion bar key and torsion bar nut; the lower part of the torsion bar spring The torsion grating scale is rigidly connected to the middle of the support sleeve, and the torsion drive mechanism drives the torsion drive motor to move;

The pendulum assembly includes a pendulum, an air bearing sleeve, a oscillating grating ruler, a plane air bearing guide rail, a rotating motor bracket, and a rotating brake cylinder. On the floating lower plate, the inner cavity of the hollow cylinder of the air bearing sleeve and the outer surface of the lower cylinder of the support sleeve adopt clearance fit; the middle part of the pendulum is a hollow cylindrical structure, which is connected with the outer surface of the cylinder of the air bearing sleeve to form a rigid connection with bolts, and the upper part of the pendulum is installed The torsion pendulum drive motor, the middle area of the lower part of the pendulum is a plane structure, the front and rear sides are arc curved surfaces, the oscillating grating scale is installed on the arc surface, and the front and rear sides of the pendulum are matched with the plane of the plane air bearing guide rail. Compressed air is introduced into the gap to form a flat air film, and the pendulum swings along the air-floating guide rail without damping; the bottom of the air-floating guide rail is fixedly installed on the lower plane of the base frame, and the two sides of the rotating motor bracket are rigidly connected To the bottom plane of the pendulum, the lower surface of the middle part is rigidly connected to the stator of the rotating motor through bolts; the cylinder liner of the brake cylinder is connected to the upper surface of the middle part of the rotating motor bracket;

The pendulum return to zero assembly includes a friction wheel, a zero return screw, a pressure sensor, a pendulum return to zero drive motor, and a zero return reducer, wherein the output end of the return to zero reducer is fixed on the base frame, and the output of the return to zero reducer The shaft is rigidly connected to one end of the zero return screw, the input shaft of the zero return reducer is fixedly connected to the output shaft of the pendulum return zero drive motor, the stator of the pendulum return zero drive motor is fixedly connected to the input end of the zero return reducer, and the pressure sensor One end is connected with the zero-return screw, and the other end is connected with the friction wheel. The friction wheel can roll on the planes of the left and right sides of the pendulum, and can be completely separated from the pendulum to ensure the free swing of the pendulum.

Among them, the torsion motion drive mechanism is composed of a driving gear and a follower gear, the follower gear is rigidly installed on the middle of the support sleeve, the drive gear and the torsion drive motor are rigidly connected through the gear key; the torsion drive motor is connected to the pendulum through the torsion drive motor bracket Make a rigid connection.

Among them, the torsion drive motor drives the driving gear to rotate for one revolution, and the main and follower gears mesh and separate once; when the gears are engaged, the driving gear drives the follower gear, torsion bar spring, support sleeve and air floating ball head to rotate together, and the main and follower gears rotate together. After the moving gear is separated, under the action of the torsional restoring moment of the torsion bar spring, the rigidly connected air-floating ball head, the air-floating sleeve, the torsion bar spring, and the follower gear together perform torsion motion around the axis of the torsion bar spring.

Wherein, the rotating motor support is in the shape of an inverted "几".

Wherein, the compressed air is passed into the brake cylinder, and the moving cylinder of the brake cylinder moves toward the central axis, and finally is pressed onto the coupling joint, thereby achieving the effect of locking the spring root of the torsion bar.

Wherein, the support sleeve of the swing bar assembly and the torsion bar spring are rigidly connected through keys and bolts at the air float ball head.

Wherein, the position of the ball center of the air floating ball head is higher than the interface plane.

Among them, a certain pressure of compressed air is passed between the air float ball head and the air float ball socket to form a spherical air film, and a certain pressure of compressed air is passed between the plane air float guide rail and the pendulum to form a double-sided rectangular air film.

Among them, a certain pressure of compressed air is introduced between the air bearing sleeve and the support sleeve, and between the air bearing sleeve and the flat air bearing lower plate to form a columnar air film and a plane annular air film respectively. The bottom of the spring is tightly held, and the torsion drive motor drives the torsion mechanism to rotate, so that the air float ball head and the swing rod assembly form an initial torsion angle; the torsional moment is released, and under the action of the torsion bar spring, the air float ball head and the swing rod assembly are wound around the plumb weight The shaft performs undamped torsional motion.

Among them, the torsion grating ruler has two measurement functions, that is, to measure the rotation angle of the ball head relative to the base frame, to determine the angle parameter between the product under test and the movement direction of the pendulum assembly, and to determine the orientation of the product under test; It is to measure the angle of the torsion pendulum in real time when the ball head and the pendulum rod make undamped torsion pendulum motion around the plumb axis to obtain the torsion pendulum period, and further calculate the parameters of the moment of inertia around the torsion pendulum axis.

Wherein, the driving gear is a single-toothed gear, and the driven gear has multiple teeth. 8. The system composition according to claim 7, characterized in that: the driving gear (24) is connected through the output shaft (25) of the torsion drive motor (20) through the gear key (26). The follower gear (23) is connected with the support sleeve (3) through tight fit.

Wherein, the screw movement of the zero-return screw of the pendulum return-to-zero assembly has only translational motion and no rotary motion.

Wherein, the lower edge of the pendulum is used for installing the bottom edge of the oscillating grating scale, and the center of the circle where it is located coincides with the center of the ball head.

The above-mentioned multi-parameter spherical air bearing quality characteristic test bench performs the method for spacecraft quality characteristic test, comprising the following steps:

1) The spacecraft is installed once on the multi-parameter spherical air bearing quality characteristic test bench;

2) Use the measurement data of the return-to-zero lead screw and the swinging grating ruler to adjust the level of the docking plane of the air-floating ball head, record the measurement value of the pressure sensor, and use the measurement software to measure the first horizontal centroid data of the spacecraft.

3) Use the rotating motor to rotate the spacecraft 90°counterclockwise around the plumb axis.

4) Again, adjust the level of the docking plane of the air float ball head, record the measured value of the pressure sensor, and use the measurement software to measure the center of mass data of the second horizontal direction of the spacecraft.

5) Under the condition that the docking plane of the air float head is horizontal, the rotating brake cylinder holds the torsion bar spring tightly, drives the torsion motion drive mechanism, makes the air float ball head and the spacecraft do torsion motion together, and uses the measurement software to record the torsion grating scale The period, amplitude, phase and other information of the torsional pendulum motion are measured, and the moment of inertia around the plumb axis can be calculated through the period of the torsional pendulum motion.

6) The zero-return screw is pushed out in reverse, so that the docking plane of the air float ball head has an included angle of 2° with the horizontal plane, and the zero-return screw is quickly withdrawn, so that the air float ball head and the spacecraft can freely swing around the center of the ball. The grating ruler measures the swing motion, and the measurement software is used to record the cycle, amplitude, phase and other information of the swing motion. The first moment of inertia around the horizontal axis can be calculated through the swing cycle, and the center of mass data in the height direction of the spacecraft can be calculated through the phase information.

7) Driven by the rotating motor, the spacecraft is rotated 90° clockwise around the plumb axis. Repeat step 6) to calculate the moment of inertia of the second horizontal axis.

8) Driven by the rotating motor, the spacecraft is rotated 45° clockwise around the plumb axis. Repeat step 6) to calculate the moment of inertia of the third horizontal axis. Through the moment of inertia values of the three horizontal axes measured above, one can calculate a parameter of the product of inertia about the two horizontal axes.

9) Driven by the rotating motor, the spacecraft rotates at a constant speed (60rpm), records the measured value of the pressure sensor and the angle value of the torsion grating ruler, and obtains the inertial product parameter of the plumb shaft through the calculation of the above parameters .

Through the above operations, using the multi-parameter spherical air bearing quality characteristic test bench, all the quality characteristic parameters can be measured without using a three-coordinate transformation machine. Realized the final purpose of the present invention.

The invention adopts the technical way of spherical air bearing measurement, does not need to use a three-coordinate conversion machine to participate in the process of quality characteristic measurement, improves the bearing capacity of the test bench, overcomes the technical difficulty of developing a large-scale three-coordinate conversion machine, and thus realizes the center of mass , Moment of inertia, and product of inertia integrated testing, improve the test accuracy of product of inertia through the method of dynamic balance.

Description of drawings

Fig. 1 is the structural schematic diagram of multi-parameter spherical air bearing quality characteristic test bench of the present invention;

Among them, 1 is the air-floating ball head; 2 is the torsion bar spring; 3 is the support sleeve; 4 is the base frame; 5 is the air-floating ball socket; 6 is the torsion movement driving mechanism; 9 is the zero return screw; 10 is the pressure sensor; 11 is the swing grating ruler; 12 is the plane air bearing lower plate; 13 is the rotating motor; 14 is the pendulum return to zero drive motor; Motor bracket; 17 is a rotary brake cylinder; 18 is a pendulum; 19 is a plane air bearing guide rail; 20 is a torsion drive motor; 21 is a torsion grating ruler; 22 is a spherical center.

Fig. 2 is the structural diagram of the pendulum assembly of the multi-parameter spherical air bearing quality characteristic test bench of the present invention

Among them, 1 is the air-floating ball head; 2 is the torsion bar spring; 4 is the base frame; 5 is the air-floating ball socket; 12 is the plane air-floating lower plate; 13 is the rotating motor; 23 is the driving gear; 24 is the follower gear; 25 is the output shaft of the torsion drive motor; 27 is the torsion bar nut; 28 is the torsion bar flange; 29 is the rotary motor coupling; 30 is the torsion drive motor shaft coupling device.

Fig. 3 is a structural diagram of the torsional motion driving mechanism of the multi-parameter spherical air bearing quality characteristic test bench of the present invention.

Wherein, 3 is a supporting sleeve; 20 is a torsion drive motor; 23 is a driving gear; 24 is a follower gear; 25 is an output shaft of a torsion drive motor; 26 is a gear key.

Fig. 4 is the structural diagram of the pendulum assembly of the multi-parameter spherical air bearing quality characteristic test bench of the present invention

Among them, 2 is a torsion bar spring; 3 is a support sleeve; 7 is an air bearing sleeve; 8 is a friction wheel; 9 is a screw for returning to zero; 11 is a swing grating ruler; 16 is a rotating motor support; 17 is a rotating brake cylinder; 18 is a pendulum; 19 is a plane air bearing guide rail; 29 is a rotating motor shaft coupling; 31 is a swing grating ruler support; 32 is a plane air bearing guide rail support.

Fig. 5 is a structural diagram of the pendulum assembly parts of the multi-parameter spherical air bearing quality characteristic test bench of the present invention

Among them, 4 is the base frame; 8 is the friction wheel; 9 is the zero return screw; 10 is the pressure sensor; 11 is the swing grating ruler; 18 is the pendulum; 33 is the follower gear of the zero return reducer; 34 is the zero return wire Female; 35 is the zero return motor; 36 is the zero return motor coupling; 37 is the zero return reducer driving gear; 38 is the zero return motor mounting bracket; 39 is the zero return shaft connection key; 40 is the zero return shaft.

Detailed ways

Specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings. These specific implementations are only exemplary and not intended to limit the protection scope of the present invention.

The structural composition of the multi-parameter spherical air bearing quality characteristic test bench is shown in Figure 1. The multi-parameter spherical air bearing quality characteristic test bench has a system structure consisting of a ball air bearing assembly, a pendulum assembly, a pendulum assembly and a pendulum return to zero The component consists of four parts.

The ball air bearing assembly is composed of an air floating ball head, an air floating ball socket, and a base frame. The structure of the ball air bearing assembly is shown in Figure 2. The air floating ball head is located on the top of the whole equipment, the upper part is the docking table, which provides the mechanical interface of the tested part, and the lower part is the spherical structure, and the center of the spherical segment is higher than the interface plane. The lower part of the air float ball socket is designed with an annular air channel and an annular sealing groove, and a sealing ring is installed in the sealing groove. The lower part of the air flotation ball socket and the upper part of the base frame are rigidly connected together by bolts to form an air supply chamber, which provides pressure-balanced compressed air for the air film between the air flotation ball head and the air flotation ball socket. There are many interception holes designed on the spherical surface of the air flotation ball socket, the compressed air flows out from the interception holes, and forms an air film with a thickness of about 0.1mm together with the spherical surface of the air flotation ball head. The air float ball head can perform three kinds of undamped movements around the center of the ball in the air float ball socket. One is to perform pendulum motion in the vertical plane; Yes, a compound movement of the above two movements. The base frame is the installation basis of the entire equipment, and its main functions are: one is to bear all the loads, and the other is the carrier for the installation of other components. The base frame is a cubic frame structure, and the lower part and the ground are fixed with the concrete foundation through anchor bolts, providing a stable and firm installation foundation for the entire equipment.

The swing rod assembly is composed of a support sleeve, a torsion bar spring, a torsion motion drive mechanism, a torsion grating scale, a torsion drive motor, a flat air bearing lower plate, and a rotating motor. The structure of the pendulum assembly is shown in Figure 2. The swing rod assembly is the actuator and measurement mechanism for the torsional movement of the air float ball head in the horizontal plane. The main function of the support sleeve is to connect the air float ball head and the pendulum assembly to form a pendulum subsystem. The support sleeve of the hollow tubular structure is rigidly connected with the bottom of the air flotation ball head by bolts at the upper part, and rigidly connected with the lower plate of the plane air flotation by bolts at the lower part. The torsion bar spring is one of the main executive parts of the torsional swing movement. The torsion bar spring runs through the inside of the support sleeve, and the upper part of the torsion bar spring is rigidly connected to the bottom of the air float ball head through a flat key structure and a thread structure. The lower part of the torsion bar spring is tightly connected with the rotating motor through a coupling. The torsion scale is rigidly attached to the center of the support sleeve. The torsional motion driving mechanism is mainly composed of a driving gear and a follower gear. The structure of the torsion drive mechanism is shown in Figure 3. The follower gear is rigidly installed on the middle position of the support sleeve through the bolt structure. The driving gear and the torsion driving motor are rigidly connected through the gear key structure, and the torsion driving motor is rigidly connected to the pendulum through the torsion driving motor bracket. Wherein, the driving gear is a single-tooth gear, and the follower gear is a multi-tooth gear. When controlling the torsion motion, the torsion drive motor drives the driving gear to rotate once, and the main and driven gears mesh and separate once. From engagement to separation, the driving gear drives the follower gear, the torsion bar spring, the support sleeve and the air floating ball head to rotate together. After the main and driven gears are separated, under the action of the restoring moment of the torsion bar spring, the rigidly connected air-floating ball head, the air-floating sleeve and the torsion bar spring jointly perform torsion motion. The square of the period of the torsional motion is proportional to the moment of inertia of all objects in the torsional motion. This law is the theoretical basis for the test of the moment of inertia of the vertical axis.

The pendulum assembly consists of a pendulum, an air bearing sleeve, a swing grating scale, a plane air bearing guide rail, a rotating motor bracket, and a rotating brake cylinder. The air flotation sleeve is a hollow cylinder structure, and the air flotation sleeve is set on the lower part of the support sleeve and placed on the air flotation lower plate. The inner cavity of the hollow cylinder and the outer surface of the lower cylinder of the support sleeve adopt clearance fit, and compressed air is introduced into the clearance to form a columnar air film. After compressed air is introduced between the lower surface of the air flotation sleeve and the upper surface of the air flotation lower plate, a circular air film can be formed. The columnar air film and circular air film ensure that the moving parts do not rub against the air bearing sleeve when the torsion bar spring, the support sleeve and the air flotation ball head perform torsion motion, and that the torsion motion is undamped. The middle part of the pendulum is a hollow cylindrical structure, and the outer surface of the cylinder of the air bearing sleeve adopts a composite fixing form of tight fit and bolt connection, so that the pendulum and the air bearing sleeve are rigidly connected. A torsional pendulum drive motor is installed on the upper part of the pendulum. The middle area of the lower part of the pendulum is a plane structure, and the front and rear sides are curved surfaces. The central axis of the curved surface passes through the center of the air-floating ball head. The oscillating grating ruler is installed on the arc surface at the lower part of the pendulum. The friction wheel can roll on the planes of the left and right sides of the pendulum, and can adjust the levelness of the upper surface of the air floating ball head. The planes of the front and rear sides of the pendulum and the plane of the plane air-floating guide rail adopt clearance fit, and compressed air is introduced into the gaps of the front and rear sides of the pendulum to form plane air films respectively. The pendulum can perform undamped simple harmonic swing along the air bearing guide rail. The swing grating scale measures the swing parameters of the pendulum such as: swing amplitude, equilibrium position, swing period. Through the analysis and calculation of these parameters, the transverse axis inertia and longitudinal center of mass parameters of the specimen can be obtained. The bottom of the air-floating guide rail is fixedly installed on the lower plane of the base frame. The installation position of the air-floating guide rail needs to ensure that the docking plane of the air-floating ball head is horizontal along the front and rear directions of the pendulum. The bracket of the rotating motor is in the shape of an inverted "Ji", both sides are rigidly connected to the bottom plane of the pendulum by bolts, and the lower surface of the middle part is rigidly connected to the stator of the rotating drive motor by bolts. The rotary brake cylinder includes two parts, the brake cylinder and the coupling. The cylinder liner of the brake cylinder is connected to the upper surface of the middle part of the rotating motor support by bolts. The compressed air is introduced into the brake cylinder, and the moving cylinder of the brake cylinder moves toward the central axis, and is finally pressed onto the coupling joint to achieve the effect of locking the spring root of the torsion bar.

The pendulum return to zero assembly consists of a friction wheel, a return to zero lead screw, a pressure sensor, a drive motor for the pendulum to return to zero, and a return to zero reducer. The structural composition of the pendulum back to zero assembly is shown in Figure 5. There are 2 sets of pendulum return components, which are respectively installed on the left and right sides of the pendulum component. The zero return reducer is fixedly installed on the base frame at the output end; the follower gear of the zero return reducer and the screw nut are fixedly connected by bolts, the zero return screw and the screw nut cooperate, and through the rotation of the screw nut, the zero return screw The rod can move back and forth to realize the function of returning the pendulum to zero; the input shaft of the zero returning reducer and the input shaft of the pendulum returning to zero driving motor are fixedly connected through the connecting shaft joint of the returning zero motor. The stator of the pendulum return to zero drive motor is fixedly connected to the input end of the zero return reducer. One end of the pressure sensor is connected with the zero return screw, and the other end is connected with the friction wheel. The friction wheel can not only roll on the planes of the left and right sides of the pendulum, but also be completely separated from the pendulum to ensure the free swing of the pendulum.

The implementation steps for testing the center of mass, moment of inertia and product of inertia of a spacecraft using a multi-parameter spherical air bearing mass characteristic test bench are as follows:

(1) Use the spacecraft sling with a hook scale to hoist the spacecraft and fix it on the multi-parameter spherical air bearing quality characteristic test bench, and calculate the mass m of the spacecraft by measuring the quality difference before and after hoisting;

(2) A certain pressure of compressed air is introduced between the air float ball head and the air float ball socket to form a spherical air film.

(3) According to the measurement data of the oscillating grating ruler, use the zero return screw to adjust the docking plane of the air float ball head to a horizontal state, and the levelness is better than 0.02mm/m; record the measured value F of the pressure sensor at this time. Calculate the first horizontal center of mass of the product (denoted as Y _c ) by the following calculation formula.

Y _c =F×L/m;

In the formula: Y _c ——horizontal Y-axis centroid;

F - the measured value of the pressure sensor;

L - the distance from the installation position of the pressure sensor to the center of the ball;

(4) Between the air flotation sleeve and the support sleeve, as well as the air flotation sleeve and the flat air flotation lower plate, a certain pressure of compressed air is introduced to form a columnar air film and a plane annular air film respectively. According to the measurement data of the torsion grating scale, the rotating motor is used to make the spacecraft rotate 90°counterclockwise around the plumb axis. Release the compressed air between the air bearing sleeve and the support sleeve, as well as the air bearing sleeve and the flat air bearing lower plate.

(5) According to the measurement data of the oscillating grating ruler, use the zero-return screw to adjust the docking plane of the air float ball head to a horizontal state, record the measured value of the pressure sensor at this time, and calculate the second transverse centroid of the product ( denoted as Z _c ). The calculation formula is the same as that of the first transverse centroid Y _c .

(6) Between the air flotation sleeve and the support sleeve, as well as the air flotation sleeve and the flat air flotation lower plate, a certain pressure of compressed air is introduced to form a columnar air film and a plane annular air film respectively. Use the zero return screw to adjust the docking plane of the air float ball head to a horizontal state. Pass compressed air into the brake cylinder, and rotate the brake cylinder to hold the torsion bar spring tightly.

(7) Turn on the torsion motion drive mechanism, so that the air float ball head and the spacecraft do torsion motion together, use the measurement software to record the torsion motion cycle T _N , amplitude, phase and other information obtained by the torsion grating ruler, through the cycle of the torsion motion, Calculate the moment of inertia around the plumb axis (denoted as I _x ). Calculated as follows:

I _x = K x T _N ² .

In the formula: I _x ——moment of inertia around the X axis;

K——The torsional stiffness coefficient of the torsion bar spring;

T _N ——torsion period;

(8) Release the compressed air between the air flotation sleeve and the support sleeve, as well as between the air flotation sleeve and the flat air flotation lower plate. Completely retract the zero-return screw with a small pressure value, and reversely push out the zero-return screw with a large pressure value, so that the docking plane of the air float ball head has an included angle of 1° with the horizontal plane.

(9) Quickly withdraw the return-to-zero screw, so that the air-floating ball head and the spacecraft can freely swing around the center of the ball. The oscillating grating scale measures the oscillating motion and records information such as the period T _z , amplitude, and equilibrium phase angle θ of the pendulum oscillating motion. The first moment of inertia around the horizontal axis (denoted as I _y ) is calculated through the swing period of the pendulum, and the center-of-mass data in the height direction of the spacecraft (denoted as X _c ) can be calculated through the phase information.

The calculation formula for calculating around the horizontal axis is:

I _y =(mgL ₀ T _z ² )/(4π ² )

In the formula: I _y ——moment of inertia around the Y axis;

m - the mass of the spacecraft;

g - acceleration of gravity;

T _z ——oscillation period;

L ₀ ——the distance from the center of mass of the spacecraft to the center of the sphere;

The formula for calculating the center of mass in the altitude direction of the spacecraft is:

X _c ＝Y _c ×ctg(θ)

In the formula: X _c —— longitudinal X-axis centroid;

Y _c ——horizontal Y-axis centroid;

θ——equilibrium phase angle;

(10) Between the air flotation sleeve and the support sleeve, as well as the air flotation sleeve and the flat air flotation lower plate, a certain pressure of compressed air is introduced to form a columnar air film and a plane annular air film respectively. According to the measurement data of the torsion grating scale, the rotating motor is used to make the spacecraft rotate 90°counterclockwise around the plumb axis. Release the compressed air between the air bearing sleeve and the support sleeve, as well as the air bearing sleeve and the flat air bearing lower plate.

(11) Repeat step (9) to calculate the moment of inertia of the second horizontal axis (denoted as I _z ). The calculation formula is the same as the first moment of inertia I _y around the horizontal axis.

(12) Between the air flotation sleeve and the support sleeve, as well as the air flotation sleeve and the flat air flotation lower plate, a certain pressure of compressed air is introduced to form a columnar air film and a plane annular air film respectively. According to the measurement data of the torsion grating scale, the rotating motor is used to make the spacecraft rotate 45°counterclockwise around the plumb axis. Release the compressed air between the air bearing sleeve and the support sleeve, as well as the air bearing sleeve and the flat air bearing lower plate.

(13) Repeat step (9) to calculate the moment of inertia of the third horizontal axis (denoted as I ₃ ). Through the moment of inertia values of the three horizontal axes measured above, a product of inertia parameter (denoted as I _yz ) about the two horizontal axes can be calculated. The calculation formula is:

I _yz =(I _y +I _z -2×I ₃ )/2

In the formula: I _yz —— product of inertia about Y axis and Z axis;

I _y —moment of inertia around the Y axis;

I _z —moment of inertia around the Z axis;

I ₃ —moment of inertia around the third axis;

(14) Between the air flotation sleeve and the support sleeve, as well as the air flotation sleeve and the flat air flotation lower plate, a certain pressure of compressed air is introduced to form a columnar air film and a plane annular air film respectively. According to the measurement data of the oscillating grating ruler, use the zero return screw to adjust the docking plane of the air float ball head to a horizontal state,

(15) Control the movement of the rotating motor, the spacecraft rotates at a constant speed at a certain speed ω (for example: 60rpm), and records the measured value of the pressure sensor and the angle value of the torsion grating ruler in real time. The measurement software can calculate two parameters of the product of inertia about the plumb axis (denoted as I _xy and I _zx ) by analyzing the above two measured values.

The formula for calculating the product of inertia parameter about the plumb axis is as follows:

In the formula: I _xy - product of inertia about X axis and Y axis;

I _zx —— product of inertia about X-axis and Z-axis;

e——transverse centroid offset,

ω—rotation speed;

t - time;

ψ ₀ ——sensor azimuth;

ψ ₁ ——the azimuth angle of the center of mass,

ψ ₂ ——the azimuth angle of moment of unbalanced couple;

Note: Other unmarked symbols have the same meaning as those in the above formula.

Claims (14)

1. Multi-parameter spherical air bearing quality characteristic test bench, including ball air bearing assembly, pendulum assembly, pendulum assembly and two sets of pendulum return components respectively installed on the left and right sides of the pendulum assembly, of which: Ball air bearing assembly includes air float ball head, air float ball socket, base frame; Ball segment structure, the position of the center of the ball is higher than the docking plane, and compressed air is passed between the segment and the air-floating ball socket to generate an air film, and the air-floating ball head performs undamped movement in the air-floating ball socket; the base frame is The cubic frame structure is the installation basis of the entire equipment, and the lower part of the air float ball socket and the upper part of the base frame are rigidly connected by bolts; The swing rod assembly is composed of a support sleeve, a torsion bar spring, a torsion motion drive mechanism, a torsion grating scale, a torsion drive motor, a flat air bearing lower plate, and a rotating motor. The support sleeve is a hollow tubular structure, and the upper part and the bottom of the air float ball head pass through The bolts are rigidly connected, the lower part is rigidly connected with the plane air bearing lower plate through bolts, the torsion bar spring runs through the inside of the support sleeve, the upper part of the torsion bar spring is rigidly connected with the bottom of the air flotation ball head through the torsion bar key and torsion bar nut; the lower part of the torsion bar spring The torsion grating scale is rigidly connected to the middle of the support sleeve, and the torsion drive mechanism drives the torsion drive motor to move; The pendulum assembly includes a pendulum, an air bearing sleeve, a oscillating grating ruler, a plane air bearing guide rail, a rotating motor bracket, and a rotating brake cylinder. On the floating lower plate, the inner cavity of the hollow cylinder of the air bearing sleeve and the outer surface of the lower cylinder of the support sleeve adopt clearance fit; the middle part of the pendulum is a hollow cylindrical structure, which is connected with the outer surface of the cylinder of the air bearing sleeve to form a rigid connection with bolts, and the upper part of the pendulum is installed The torsion pendulum drive motor, the middle area of the lower part of the pendulum is a plane structure, the front and rear sides are arc curved surfaces, the oscillating grating scale is installed on the arc surface, and the front and rear sides of the pendulum are matched with the plane of the plane air bearing guide rail. Compressed air is introduced into the gap to form a flat air film, and the pendulum swings along the air-floating guide rail without damping; the bottom of the air-floating guide rail is fixedly installed on the lower plane of the base frame, and the two sides of the rotating motor bracket are rigidly connected To the bottom plane of the pendulum, the lower surface of the middle part is rigidly connected to the stator of the rotating motor through bolts; the cylinder liner of the brake cylinder is connected to the upper surface of the middle part of the rotating motor bracket; The pendulum return to zero assembly includes a friction wheel, a zero return screw, a pressure sensor, a pendulum return to zero drive motor, and a zero return reducer, wherein the output end of the return to zero reducer is fixed on the base frame, and the output of the return to zero reducer The shaft is rigidly connected to one end of the zero return screw, the input shaft of the zero return reducer is fixedly connected to the output shaft of the pendulum return zero drive motor, the stator of the pendulum return zero drive motor is fixedly connected to the input end of the zero return reducer, and the pressure sensor One end is connected with the zero-return screw, and the other end is connected with the friction wheel. The friction wheel can roll on the planes of the left and right sides of the pendulum, and can be completely separated from the pendulum to ensure the free swing of the pendulum. 2. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein the torsional motion drive mechanism is composed of a driving gear and a follower gear, the follower gear is rigidly installed on the middle part of the support sleeve, and the drive gear and The torsion drive motor is rigidly connected through the gear key; the torsion drive motor is rigidly connected to the pendulum through the torsion drive motor bracket. 3. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 2, wherein the torsion drive motor drives the driving gear to rotate for one revolution, and the main and follower gears mesh and separate once; when the gears mesh, the driving gear drives the follower The driving gear, torsion bar spring, support sleeve and air flotation ball head are twisted together. After the main and driven gears are separated, under the action of the torsional recovery torque of the torsion bar spring, the rigidly connected air flotation ball head, air flotation ball The sleeve, the torsion bar spring and the follower gear jointly perform torsion motion around the axis of the torsion bar spring. 4. The multi-parameter spherical air bearing quality characteristic test bench according to claim 1, wherein the rotating motor bracket is in the shape of an inverted "几". 5. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein compressed air is introduced into the brake cylinder, and the moving cylinder of the brake cylinder moves toward the central axis, and is finally pressed onto the coupling , to achieve the effect of locking the root of the torsion bar spring. 6. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein, the support sleeve of the pendulum assembly and the torsion bar spring are rigidly connected by keys and bolts at the air bearing ball head. 7. The multi-parameter spherical air bearing quality characteristic test bench according to claim 1, wherein the position of the center of the air bearing head is higher than the interface plane. 8. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein, a certain pressure of compressed air is introduced between the air bearing head and the air bearing socket to form a spherical air film, A certain pressure of compressed air is passed between the guide rail and the pendulum to form a double-sided rectangular air film. 9. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein, between the air bearing sleeve and the support sleeve, and between the air bearing sleeve and the plane air bearing lower plate, a certain pressure compression The air forms a columnar air film and a flat annular air film respectively, and the rotating brake cylinder holds the bottom of the torsion bar spring tightly, and the torsion drive motor drives the torsion pendulum mechanism to rotate, so that the air float ball head and the pendulum bar assembly form an initial torsion angle; release the torsion moment , under the action of the torsion bar spring, the air float ball head and the pendulum bar make undamped torsion motion around the plumb shaft. 10. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein, the torsion grating ruler has two measuring functions, that is, the first is to measure the rotation angle of the ball head relative to the base frame, so as to determine the relationship between the product under test and the base frame. The angle parameter of the movement direction of the pendulum assembly is used to determine the orientation of the product under test; the second is to measure the angle of the torsion pendulum in real time when the ball head and the pendulum assembly are performing undamped torsion pendulum motion around the plumb axis to obtain the torsion period. Further calculate the moment of inertia parameters around the torsion axis. 11. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 3, wherein the driving gear is a single-toothed gear, the follower gear has a plurality of teeth, and the driving gear is driven by the output shaft of the torsion drive motor through the gear key. Connected, the follower gear is connected with the support sleeve through tight fit. 12. The multi-parameter spherical air bearing quality characteristic test bench as claimed in claim 1, wherein the screw movement of the zero-return screw of the pendulum return-to-zero assembly has only translational motion and no rotary motion. 13. The multi-parameter spherical air bearing quality characteristic test bench according to claim 1, wherein the lower edge of the pendulum is used for installing the bottom edge of the oscillating grating ruler, and the center of the circle where it is located coincides with the center of the ball head. 14. The method for testing the quality characteristics of spacecraft by using the multi-parameter spherical air bearing quality characteristic test bench according to any one of claims 1-13, comprising the following steps: 1) The spacecraft is installed once on the multi-parameter spherical air bearing quality characteristic test bench; 2) Use the measurement data of the return-to-zero lead screw and the swinging grating ruler to adjust the level of the docking plane of the air-floating ball head, record the measurement value of the pressure sensor, and use the measurement software to measure the first horizontal centroid data of the spacecraft; 3) Use the rotating motor to rotate the spacecraft 90°counterclockwise around the plumb axis; 4) Again, adjust the level of the docking plane of the air float ball head, record the measured value of the pressure sensor, and use the measurement software to measure the center of mass data of the second horizontal direction of the spacecraft; 5) Under the condition that the docking plane of the air float head is horizontal, the rotating brake cylinder holds the torsion bar spring tightly, drives the torsion motion drive mechanism, makes the air float ball head and the spacecraft do torsion motion together, and uses the measurement software to record the torsion grating scale Measure the period, amplitude, phase and other information of the torsional motion, and the moment of inertia around the plumb axis can be calculated through the cycle of the torsional motion; 6) The zero-returning screw is pushed out in reverse, so that the docking plane of the air-floating ball head has an angle of 2° with the horizontal plane, and the zero-returning screw is quickly withdrawn, so that the air-floating ball head and the spacecraft can freely swing around the center of the ball. The grating ruler measures the swing motion, and uses the measurement software to record the cycle, amplitude, phase and other information of the swing motion. The first moment of inertia around the horizontal axis can be calculated through the swing cycle, and the center of mass data in the height direction of the spacecraft can be calculated through the phase information; 7) Driven by the rotating motor, rotate the spacecraft 90° clockwise around the plumb axis, and repeat step 6) to calculate the moment of inertia of the second horizontal axis; 8) Under the drive of the rotating motor, make the spacecraft rotate 45° clockwise around the plumb axis, repeat the operation of step 6), and the moment of inertia of the third horizontal axis can be calculated. The three levels obtained through the above measurements The moment of inertia value of the axis can calculate a parameter of the product of inertia about two horizontal axes; 9) Driven by the rotating motor, the spacecraft rotates at a constant speed (60rpm), records the measured value of the pressure sensor and the angle value of the torsion grating ruler, and obtains the inertial product parameter of the plumb axis through the calculation of the above parameters .