CN109470200B - Device and method for measuring large-angle attitude angle of three-axis air bearing table - Google Patents

Abstract

The invention provides a device and a method for measuring a large-angle attitude angle of a three-axis air bearing table, and belongs to the technical field of high-precision attitude control and measurement. The invention installs a three-axis mechanical electric tracking rotary table outside a three-axis air bearing table system, and respectively installs an eddy current displacement sensor on the three-axis mechanical electric tracking rotary table and a metal block on the inner side of an instrument platform of the three-axis air bearing table, controls the three-axis mechanical electric tracking rotary table to track in real time after the three-axis air bearing table moves so that a measurement value l of the eddy current displacement sensor is unchanged, obtains the attitude angle of the three-axis air bearing table by reading the angle value of the movement of the three-axis mechanical electric tracking rotary table, and analyzes the numerical relation between the attitude angle error of the three-axis air bearing table and related parameters. The device has the advantages of high measurement precision, no occupation of the space of an instrument platform, capability of realizing real-time measurement, quick tracking, 360-degree full-rotation measurement and the like.

Description

Device and method for measuring large-angle attitude angle of three-axis air bearing table

Technical Field

The invention relates to a device and a method for measuring a large-angle attitude angle of a three-axis air bearing table, and belongs to the technical field of high-precision attitude control and measurement.

Background

With the increasing requirements of satellite model loads on platform functions, the attitude and orbit control subsystem is used as an important subsystem of a satellite to bear the key task of whole satellite success and failure, and various models require full physical tests to be carried out to verify corresponding functional models. The triaxial air bearing table is used as core equipment of a ground aircraft full-physical simulation test, the friction torque is small during air bearing, and a special mechanical environment of a satellite in orbit can be simulated. The three-axis air bearing table attitude measurement device is key equipment of a three-axis air bearing table and is used for realizing real-time measurement and calculation of an attitude angle of the three-axis air bearing table.

The traditional large-angle attitude angle measuring device of the triaxial air bearing table adopts a scheme of a fiber-optic gyroscope combination or a laser tracker. The optical fiber gyro combination is characterized in that angular position information is obtained by measuring the speed of the triaxial air bearing table and then integrating, the measuring precision can not meet the technical index requirement due to the drift problem of long-time work of the gyro, and the gyro occupies large space of an instrument platform; the method for measuring the attitude angle of the three-axis air bearing table by using the laser tracker is characterized in that an optical target ball is placed on the three-axis air bearing table, the laser tracker under the table tracks the optical target ball to obtain different position coordinates to calculate the attitude angle information of the three-axis air bearing table, if the full-rotation tracking needs two or three laser trackers, the project cost is increased, and the method also has the problems of low tracking speed, small tracking angle and the like. The device for measuring the wide-angle attitude angle of the three-axis air bearing table has the advantages of high measurement precision, no occupation of instrument platform space, capability of realizing real-time measurement, quick tracking, 360-degree full-rotation measurement and the like.

Disclosure of Invention

The invention aims to solve the problems in the prior art, and further provides a device and a method for measuring a large-angle attitude angle of a three-axis air bearing table.

The purpose of the invention is realized by the following technical scheme:

a triaxial air bearing table large angle attitude angle measuring device comprises: the device comprises a three-axis air floating table, a three-axis mechanical and electric tracking rotary table, an eddy current displacement sensor and a metal block;

the three-axis mechanical electric tracking rotary table is arranged on the outer side of the three-axis air bearing table, an eddy current displacement sensor is arranged on the three-axis mechanical electric tracking rotary table, a metal block is arranged on the inner side of an instrument platform of the three-axis air bearing table, the rotating center of the three-axis mechanical electric tracking rotary table and the rotating center of the eddy current displacement sensor are arranged on a straight line, and the three-axis mechanical electric tracking rotary table is parallel to each corresponding rotating shaft of the three-axis air bearing table;

the three-axis air bearing table consists of a three-axis air bearing table base, a three-axis air bearing table upright post, a three-axis air bearing table air bearing ball and an instrument platform; the device comprises a three-axis air bearing table base, an adjusting sizing block, a three-axis air bearing table upright post, a three-axis air bearing table air floating ball bearing, an instrument platform, a three-axis air floating table air floating ball and a three-axis air floating table air floating ball, wherein the three-axis air floating table base is fixed on the adjusting sizing block; a metal block is arranged at the position, corresponding to the eddy current displacement sensor, of the inner side of the instrument platform of the triaxial air bearing table;

the three-axis mechanical electric tracking rotary table consists of an outer ring part, an outer ring support column, a middle ring part and an inner ring part; the outer ring component adopts an outer rotor motor, an outer ring shaft static part motor stator and an outer ring fixed shaft are arranged on a three-shaft air bearing table upright post, the outer ring fixed shaft is connected with a three-shaft air bearing table air bearing ball bearing, an outer ring shaft rotating part motor rotor is assembled on a motor shell, the rotation axis of the outer ring shaft is superposed with the axis of the three-shaft air bearing table in the movement z-axis direction, two outer ring support columns extend out of the outer ring motor shell and are used as supports of a middle ring shaft of the middle ring component and an inner ring shaft of the inner ring component, the middle ring shaft adopts an O-shaped structure, and the middle of the middle ring component is provided with the inner ring motor; and the three shafts of the inner ring, the middle ring and the outer ring of the three-shaft mechanical electric tracking rotary table are respectively provided with an eddy current displacement sensor, and the installation direction of the eddy current displacement sensors is vertical to the axis of the corresponding shaft.

The axes of the inner ring, the middle ring and the outer ring of the three-axis mechanical electric tracking rotary table are mutually vertical, and the rotation center of the three-axis mechanical electric tracking rotary table is superposed with the rotation center of the three-axis air bearing table.

The angle measuring device of the three-axis mechanical and electric tracking rotary table is characterized in that a high-precision absolute 26-bit circular grating is arranged on a rotary shaft, the grating is connected with the rotary shaft through a grating seat, and the grating seat is designed with a precise conical surface for positioning the grating, so that the angle measuring precision can be within 2 ″.

A tetrahedral prism can be installed on the inner ring part 6 of the three-axis mechanical electric tracking turntable, and two orthogonal photoelectric autocollimators are installed on an instrument platform of the air bearing table to replace the structural scheme of the eddy current displacement sensor 9 and the metal block 10 to measure the large-angle attitude angle of the three-axis air bearing table.

The measuring method based on the three-axis air bearing table large-angle attitude angle measuring device is carried out according to the following steps:

step (ii) ofFirstly, the method comprises the following steps: setting the rotation center O of the three-axis air bearing table₁Three-axis mechanical electric tracking rotary table rotation center O₂Mounting position R of eddy current displacement sensor₂Metal block mounting position R₁D is the installation error of the three-axis air bearing table and the rotation center of the three-axis mechanical electric tracking rotary table, the distance between a displacement sensor and a metal block on the three-axis air bearing table measured by an eddy current displacement sensor on the three-axis mechanical electric tracking rotary table in the initial state is l, and the position of the metal block after the movement of the three-axis air bearing table is determined by a₁Move to a₂Controlling a three-axis mechanical electric tracking turntable to enable the position of the eddy current displacement sensor to be b to be unchanged in order to ensure that the measured value l of the eddy current displacement sensor is unchanged₁Move to position b₂Setting a three-axis air bearing table motion angle a and a three-axis mechanical and electric tracking rotary table motion angle b;

step two: when d is 0, namely the rotation error is 0, the motion angle value of the three-axis air bearing table, namely a is b, can be determined by reading the motion angle b of the three-axis electric tracking rotary table, so that the attitude angle of the three-axis air bearing table is obtained, and the measurement accuracy of the angular position of the three-axis air bearing table only depends on the angular position accuracy of the three-axis mechanical electric tracking rotary table and the accuracy of the eddy current displacement sensor;

step three: when d is not 0, the intermediate variable x is set to a for derivation convenience by using the established geometric model₁To O₂Deducing the motion angle value a of the three-axis air bearing table and the motion angle values b and R of the three-axis mechanical electric turntable₁、R₂D, l and the intermediate variable x are as follows:

step four: knowing that the motion angle of the three-axis mechanical and electric tracking rotary table is b, solving an intermediate variable x of a nonlinear equation by using MATLAB according to an equation (1), substituting the value of x into an equation (2) to solve the motion angle a of the three-axis air bearing table, and calculating the magnitude of the attitude and angular position error (b-a) of the three-axis air bearing table;

step five: obtaining the influence of each relevant parameter on the angular position precision of the triaxial air bearing table:

(1) maintenance of R₁、R₂The error l is unchanged, the error of the attitude angular position of the three-axis air bearing table linearly increases along with the increase of the rotation error d, and the error (b-a) of the angular position increases along with the increase of the motion angle b of the three-axis mechanical and electric tracking rotary table;

(2) maintenance of R₁、R₂D is unchanged, and along with the increase of the distance l between the eddy current displacement sensor and the metal block, the error (b-a) of the attitude angle position of the three-axis air bearing table is reduced;

(3) keeping l and d unchanged, and following the installation radius R of the eddy current displacement sensor and the metal block₁、R₂The increasing angular position error (b-a) decreases therewith;

by utilizing the conclusion, the angular position error of the three-axis air bearing table can be reduced by increasing the installation radius of the eddy current displacement sensor and the metal block and increasing the installation distance between the eddy current displacement sensor and the metal block.

The invention has the beneficial effects that:

the outer ring of the three-axis mechanical electric tracking rotary table adopts the outer rotor motor, so that the structural complexity is reduced; the rotation center of the three-axis air bearing table, the rotation center of the three-axis mechanical and electric tracking rotary table and the installation positions of the eddy current displacement sensors are on the same straight line, so that the complexity of the model is simplified; and the angular position measuring device of the triaxial mechanical and electric tracking rotary table adopts 26-bit high-precision circular grating, so that high-precision angular position control can be realized, and the advantages of high-precision real-time measurement of the attitude angle of the triaxial air bearing table, fast tracking, 360-degree full-rotation measurement and the like are realized.

According to the invention, a tetrahedral prism can be mounted on the inner ring component of the three-axis mechanical electric tracking rotary table, and two orthogonal photoelectric autocollimators are mounted on the instrument platform of the air bearing table to replace the eddy current displacement sensor and the metal block structure scheme to measure the large-angle attitude angle of the three-axis air bearing table, so that a new idea for measuring the large-angle attitude angle of the three-axis air bearing table is provided.

The method can analyze the numerical relationship between the attitude angle error of the three-axis air bearing table and related parameters, and summarize the rule that the angular position error of the three-axis air bearing table can be reduced by increasing the installation radius of the eddy current displacement sensor and the metal block and increasing the installation distance of the eddy current displacement sensor and the metal block.

Drawings

Fig. 1 is a schematic structural diagram of a large-angle attitude angle measuring device of a triaxial air bearing table.

FIG. 2 is a schematic diagram of a geometric model of a large-angle attitude angle measuring device of a triaxial air bearing table.

In the figure, reference numerals, 1 denotes a three-axis air bearing table base, 2 denotes a three-axis air bearing table column, 3 denotes an outer ring member, 4 denotes an outer ring support column, 5 denotes a middle ring member, 6 denotes an inner ring member, 7 denotes a three-axis air bearing table air bearing ball, 8 denotes a three-axis air bearing table air bearing ball, 9 denotes an eddy current displacement sensor, and 10 denotes a metal block.

Detailed Description

The invention will be described in further detail below with reference to the accompanying drawings: the present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation is given, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1 and fig. 2, a device and a method for measuring a large-angle attitude angle of a three-axis air bearing table according to the present embodiment includes:

a high-precision three-axis mechanical and electric tracking rotary table is mounted on the outer side of an air bearing of a three-axis air floating table, a high-precision absolute 26-bit circular grating is mounted on a rotating shaft of the three-axis mechanical and electric tracking rotary table, the grating is connected with the rotating shaft through a grating seat, and the grating seat is designed with a precision conical surface for grating positioning, so that high-precision angle position control of angle measurement precision within 2' can be realized. The rotating shaft of the three-axis mechanical and electric tracking rotary table can move at the same position as the rotating center angle of the three-axis mechanical and electric tracking rotary table, and can be any one of the outer ring shaft, the middle ring shaft and the inner ring shaft. During installation, the rotation centers of an inner shaft, a middle shaft and an outer shaft of a three-shaft mechanical electric tracking rotary table are ensured to be coincided with the rotation center of a three-shaft air bearing table, an eddy current displacement sensor 9 is respectively installed on each shaft of the three-shaft mechanical electric tracking rotary table, a corresponding metal block 10 is installed on the inner side of an instrument platform of the air bearing table, the corresponding position relation of the three-shaft air bearing table and the three-shaft mechanical electric tracking rotary table can be measured through the eddy current displacement sensor 9, the initial position of the three-shaft air bearing table and the three-shaft mechanical tracking rotary table is determined, the distance l between each eddy current displacement sensor and the metal block is recorded, the value read by the eddy current displacement sensor 9 starts to change after the three-shaft air bearing table moves, the three-shaft mechanical electric tracking rotary table is controlled to track the movement of the three-shaft air bearing table in real time in order to keep the value l of the eddy current, and locking the three-axis mechanical and electric tracking rotary table at the position, so that the three-axis air bearing table and the three-axis mechanical and electric tracking rotary table move by the same angular position increment, and calculating the moving attitude angle of the three-axis air bearing table by reading the corresponding angular value of the three-axis mechanical and electric tracking rotary table. The three-axis air bearing table large-angle attitude angle measuring device has the advantages of high-precision real-time measurement of the attitude angle of the three-axis air bearing table, fast tracking, 360-degree full-rotation measurement and the like.

An outer ring component 3 of a three-axis mechanical electric tracking rotary table in the three-axis air bearing table large-angle attitude angle measuring device adopts an outer rotor motor, so that the complexity of a mechanical structure can be reduced. The three-axis air bearing table structure is a three-axis air bearing table base 1 with the lowest end pressed on an adjusting sizing block, the adjusting sizing block is fixed on the ground, a three-axis air bearing table upright post 2 is arranged on the three-axis air bearing table base 1 and used for connecting the three-axis air bearing table base 1 and a three-axis air bearing table large-angle attitude angle measuring device, the three-axis air bearing table upright post 2 is provided with the large-angle attitude angle measuring device, a three-axis mechanical and electric tracking turntable outer ring shaft static part motor stator and an outer ring fixed shaft of the large-angle attitude angle measuring device are arranged on the three-axis air bearing table upright post 2, a three-axis air bearing table air bearing ball bearing 7 part is arranged on the outer ring fixed shaft, a three-axis air bearing table air bearing ball 8 is arranged on the three-axis air bearing table air bearing ball 8, and an instrument platform is. The rotor of the outer ring shaft rotating part of the three-shaft mechanical electric tracking rotary table is assembled on a motor shell, the rotation axis of the outer ring shaft of the three-shaft mechanical electric tracking rotary table is superposed with the axis of the three-shaft air bearing table in the moving z-axis direction, two outer ring supporting columns 4 extend out of the outer ring motor shell of the three-shaft mechanical electric tracking rotary table and are used as supports of a middle ring shaft of a middle ring part 5 and an inner ring shaft of an inner ring part 6, the middle ring shaft adopts an O-shaped structure to ensure the strength and stability of a mechanical structure, and the inner ring motor and a load platform of the inner ring part 6 are further installed in the middle of the middle ring part 5 of the. An eddy current displacement sensor 9 is respectively arranged on an inner shaft, a middle shaft and an outer shaft of a three-shaft mechanical electric tracking rotary table, the installation direction of the eddy current displacement sensor is required to be vertical to the axis of the corresponding shaft, a metal block 10 is arranged at a position corresponding to the eddy current displacement sensor 9 on the inner side of an instrument platform of the three-shaft air bearing table, and the assembly is as shown in figure 1. When the three-axis mechanical and electric tracking rotary table is installed, the inner ring axis, the middle ring axis and the outer ring axis of the three-axis mechanical and electric tracking rotary table are required to be vertical to each other, and the rotation center of the three-axis mechanical and electric tracking rotary table is coincident with the rotation center of the three-axis air bearing table.

When the rotation center of the three-axis air bearing table is not coincident with the rotation center of the three-axis mechanical and electric tracking rotary table, the measured value of the attitude and angular position of the three-axis air bearing table is influenced by the misalignment error. And then, analyzing the influence of the misalignment error of the rotation center on the measurement of the attitude angle of the three-axis air bearing table by establishing a geometric model.

In order to simplify the complexity of the model, it is assumed that the rotation center of the three-axis air bearing table, the rotation center of the three-axis mechanical and electric tracking turntable and the installation positions of the eddy current displacement sensor are on the same straight line, as shown in fig. 2;

setting the rotation center O of the three-axis air bearing table₁Three-axis mechanical electric tracking rotary table rotation center O₂D is the installation error of the three-axis air bearing table and the rotation center of the three-axis mechanical electric tracking rotary table, the distance between a displacement sensor and a metal block on the three-axis air bearing table measured by an eddy current displacement sensor on the three-axis mechanical electric tracking rotary table in the initial state is l, and the position of the metal block after the movement of the three-axis air bearing table is determined by a₁Move to a₂Controlling a three-axis mechanical electric tracking turntable to enable the position of the eddy current displacement sensor to be b to be unchanged in order to ensure that the measured value l of the eddy current displacement sensor is unchanged₁Move to position b₂. When d is 0, namely the rotation error is 0, the three-axis electric tracking rotation is readThe motion angle value b of the platform can determine the motion angle value of the three-axis air bearing platform, namely a is b, the attitude angle of the three-axis air bearing platform is obtained, and the angular position measurement accuracy of the three-axis air bearing platform only depends on the angular position accuracy of the three-axis mechanical and electric tracking rotary table and the accuracy of the eddy current displacement sensor. When d is not 0, the intermediate variable x is set to a for derivation convenience by using the established geometric model₁To O₂Deducing the motion angle value a of the three-axis air bearing table and the motion angle values b and R of the three-axis mechanical electric turntable₁、R₂D, l and the intermediate variable x.

Knowing that the motion angle of the three-axis mechanical and electric tracking rotary table is b, solving an intermediate variable x of a nonlinear equation by using MATLAB according to an equation (1), substituting the value of x into an equation (2) to solve the motion angle a of the three-axis air bearing table, calculating the magnitude of the attitude and angular position error (b-a) of the three-axis air bearing table, and further solving the influence of each relevant parameter on the angular position precision of the three-axis air bearing table.

In order to analyze R more intuitively₁、R₂D, l and the influence of the motion angle b of the three-axis mechanical and electric tracking rotary table on the size of the attitude angle of the three-axis air bearing table are illustrated by a table.

(1) Set R₁＝505mm，R₂500mm, 15mm, and 0.5-5 mm for d, corresponding to b being the error in the angular position of the three-axis air bearing table (in ″) at different values:

the above data show that the three-axis air-bearing table attitude angular position error (b-a) increases linearly with increasing slewing error d, and the angular position error (b-a) also increases with increasing movement angle b.

(2) Set R₁＝505mm，R₂500mm, d 0.5mm, and l 10-15 mm variation corresponds to b being the error in the angular position of the three-axis air bearing table (in ″) at different values:

(b-a)″	b＝0.1°	1°	2°	5°	10°	15°	30°
								l＝10	0.36	3.61	7.25	18.35	37.32	56.8	116.77
l＝12	0.36	3.605	7.23	18.26	37.01	56.09	113.94
								l＝15	0.36	3.6	7.22	18.19	36.72	55.43	111.36

the above data illustrates that the angular position error (b-a) decreases as the eddy current displacement sensor measures distance l from the slug.

Setting d 0.5mm, l 15mm, R₁＝505mm，R₂＝500mm；R₁＝405mm，R₂＝400mm；R₁＝305mm，R₂The 300mm variation corresponds to the error in the angular position (in ") of the three-axis air bearing table at different values of b:

the above data illustrate the radius R as the eddy current sensor is mounted to the slug₁、R₂The angular position error (b-a) decreases accordingly.

Example 1

An outer ring component 3 of a three-axis mechanical electric tracking rotary table in the three-axis air bearing table large-angle attitude angle measuring device adopts an outer rotor motor, so that the complexity of a mechanical structure can be reduced. The three-axis air bearing table structure is a three-axis air bearing table base 1 with the lowest end pressed on an adjusting sizing block, the adjusting sizing block is fixed on the ground, a three-axis air bearing table upright post 2 is arranged on the three-axis air bearing table base 1 and used for connecting the three-axis air bearing table base 1 and a three-axis air bearing table large-angle attitude angle measuring device, the three-axis air bearing table upright post 2 is provided with the large-angle attitude angle measuring device, a three-axis mechanical and electric tracking turntable outer ring shaft static part motor stator and an outer ring fixed shaft of the large-angle attitude angle measuring device are arranged on the three-axis air bearing table upright post 2, a three-axis air bearing table air bearing ball bearing 7 part is arranged on the outer ring fixed shaft, a three-axis air bearing table air bearing ball 8 is arranged on the three-axis air bearing table air bearing ball 8, and an instrument platform is. The rotor of the outer ring shaft rotating part of the three-shaft mechanical electric tracking rotary table is assembled on a motor shell, the rotation axis of the outer ring shaft of the three-shaft mechanical electric tracking rotary table is superposed with the axis of the three-shaft air bearing table in the moving z-axis direction, two outer ring supporting columns 4 extend out of the outer ring motor shell of the three-shaft mechanical electric tracking rotary table and are used as supports of a middle ring shaft of a middle ring part 5 and an inner ring shaft of an inner ring part 6, the middle ring shaft adopts an O-shaped structure to ensure the strength and stability of a mechanical structure, and the inner ring motor and a load platform of the inner ring part 6 are further installed in the middle of the middle ring part 5 of the. An eddy current displacement sensor 9 is respectively arranged on an inner shaft, a middle shaft and an outer shaft of a three-shaft mechanical electric tracking rotary table, the installation direction of the eddy current displacement sensor is required to be vertical to the axis of the corresponding shaft, a metal block 10 is arranged at a position corresponding to the eddy current displacement sensor 9 on the inner side of an instrument platform of the three-shaft air bearing table, and the assembly is as shown in figure 1. When the three-axis mechanical and electric tracking rotary table is installed, the inner ring axis, the middle ring axis and the outer ring axis of the three-axis mechanical and electric tracking rotary table are required to be vertical to each other, and the rotation center of the three-axis mechanical and electric tracking rotary table is coincident with the rotation center of the three-axis air bearing table.

Example 2

The three-axis mechanical electric tracking rotary table can be used for measuring the large-angle attitude angle of the three-axis air bearing table by mounting the eddy current displacement sensor 9, and the device can also be used for mounting a tetrahedral prism on the inner ring part 6 of the three-axis mechanical electric tracking rotary table, and two orthogonal photoelectric autocollimators are mounted on an instrument platform of the air bearing table to replace the structural scheme of the eddy current displacement sensor 9 and the metal block 10 to measure the large-angle attitude angle of the three-axis air bearing table.

Example 3

When the rotation center of the three-axis air bearing table is not coincident with the rotation center of the three-axis mechanical electric tracking rotary table, if the rotation center of the three-axis air bearing table, the rotation center of the three-axis mechanical electric tracking rotary table and the installation position of the eddy current displacement sensor are on the same straight line, the motion angle a of the three-axis air bearing table, the motion angle b of the three-axis mechanical electric tracking rotary table and the installation position R of the eddy current displacement sensor are deduced₂Metal block mounting position R₁The relationship between the measured value l of the eddy current displacement sensor and the misalignment error d of the rotation center:

and (3) solving the numerical relation between the attitude angle measurement error of the three-axis air bearing table and other parameters by utilizing Matlab:

(1) keeping R1, R2 and l unchanged, increasing the error of the attitude angular position of the three-axis air bearing table linearly along with the increase of the revolution error d, and increasing the error of the angular position (b-a) along with the increase of the motion angle b of the three-axis mechanical and electric tracking rotary table;

(2) keeping R1, R2 and d unchanged, and reducing the error (b-a) of the attitude and angular position of the three-axis air bearing table along with the increase of the distance l between the eddy current displacement sensor and the metal block;

(3) keeping l and d unchanged, and reducing the angular position error (b-a) along with the increase of the installation radiuses R1 and R2 of the eddy current displacement sensor and the metal block;

by utilizing the conclusion, the angular position error of the three-axis air bearing table can be reduced by increasing the installation radius of the eddy current displacement sensor and the metal block and increasing the installation distance between the eddy current displacement sensor and the metal block.

Example 4

The procedure for calculating the error in the angular position of the three-axis air bearing table based on MATLAB is as follows:

format long g

R1＝305；

R2＝300；

d＝0.5；

l＝15；

b＝0.1；

x＝fsolve(@(x)180/pi*acos((R1^2-d^2-x^2)/(2*x*d))-180/pi*acos((x^2-l^2+R2^2)/(2*x*R2))-b,304.512235981194)

a＝180/pi*(acos((R1^2-x^2+d^2)/(2*R1*d))-acos((R1^2-l^2+(R2+d)^2)/(2*R1*(R2+d))))

jiaoerror＝(b-a)*3600

calculating the error of the angular position of the triaxial air bearing table:

displaying the data as a long integer scientific count; setting R1 ═ 305; r2 ═ 300; d is 0.5; l is 15; b is 0.1; setting x to 304.512235981194 as an initial value, and solving the solution of x in the nonlinear equation (1); substituting the value of x into the equation (2) to solve the value of a; and (b-a) calculating the value of (b-a) and converting the value into angular seconds (unit "), and finally obtaining the attitude and angular position error of the three-axis air bearing table.

The above description is only a preferred embodiment of the present invention, and these embodiments are based on different implementations of the present invention, and the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (5)

1. The utility model provides a big angle attitude angle measuring device of triaxial air supporting platform which characterized in that includes: the device comprises a three-axis air floating table, a three-axis mechanical and electric tracking rotary table, an eddy current displacement sensor (9) and a metal block (10);

the three-axis mechanical electric tracking rotary table is arranged on the outer side of the three-axis air bearing table, an eddy current displacement sensor (9) is arranged on the three-axis mechanical electric tracking rotary table, a metal block (10) is arranged on the inner side of an instrument platform of the three-axis air bearing table, the rotating center of the three-axis mechanical electric tracking rotary table and the eddy current displacement sensor (9) are arranged on the same straight line, and the three-axis mechanical electric tracking rotary table is parallel to each corresponding rotating shaft of the three-axis air bearing table;

the three-axis air bearing table consists of a three-axis air bearing table base (1), a three-axis air bearing table upright post (2), a three-axis air bearing table air bearing ball bearing (7), a three-axis air bearing table air bearing ball (8) and an instrument platform; the device comprises a three-axis air bearing table base (1), an adjusting sizing block, a three-axis air bearing table upright post (2), a three-axis air bearing table air bearing ball bearing (7), a three-axis air bearing table air floating ball (8) and an instrument platform, wherein the three-axis air bearing table base (1) is fixed on the adjusting sizing block, the adjusting sizing block is fixed on the ground, the three-axis air bearing table upright post (2) is fixedly connected with the three-axis air bearing table base (1), the upper end of the three-axis air bearing table upright post (2) is provided with the three-axis air bearing; a metal block (10) is arranged at the position, corresponding to the eddy current displacement sensor (9), of the inner side of the instrument platform of the triaxial air bearing table;

the three-axis mechanical electric tracking turntable consists of an outer ring component (3), an outer ring support column (4), a middle ring component (5) and an inner ring component (6); the outer ring component (3) adopts an outer rotor motor, an outer ring shaft static part motor stator and an outer ring fixed shaft are arranged on a three-shaft air bearing table upright post (2), the outer ring fixed shaft is connected with a three-shaft air bearing table air bearing (7), an outer ring shaft rotating part motor rotor is assembled on a motor shell, the rotation axis of the outer ring shaft is superposed with the axis of the three-shaft air bearing table in the moving z-axis direction, two outer ring support columns (4) extend out of the outer ring motor shell and are used as supports of a middle ring shaft of the middle ring component (5) and an inner ring shaft of the inner ring component (6), the middle ring shaft adopts an O-shaped structure, and the middle part of the middle ring component (5) is provided with the inner ring motor and a load platform of the; and the three shafts of the inner ring, the middle ring and the outer ring of the three-shaft mechanical electric tracking rotary table are respectively provided with an eddy current displacement sensor (9), and the installation direction of the eddy current displacement sensors is vertical to the axis of the corresponding shaft.

2. The device for measuring the large-angle attitude angle of the three-axis air bearing table according to claim 1, wherein the axes of the inner ring, the middle ring and the outer ring of the three-axis mechanical and electrical tracking rotary table are perpendicular to each other, and the rotation center of the three-axis mechanical and electrical tracking rotary table coincides with the rotation center of the three-axis air bearing table.

3. The device for measuring the large-angle attitude angle of the three-axis air bearing table according to claim 1, wherein the angle measuring device of the three-axis mechanical and electrical tracking rotary table is a high-precision absolute 26-bit circular grating mounted on the rotary shaft, the grating is connected with the rotary shaft through a grating seat, and the grating seat is designed with a precise conical surface for positioning the grating, so that the angle measuring precision can be within 2 ″.

4. The device for measuring the large-angle attitude angle of the three-axis air bearing table according to claim 1, wherein a tetrahedral prism is mounted on the inner ring component (6) of the three-axis mechanical and electrical tracking turntable, and two orthogonal photoelectric autocollimators are mounted on the instrument platform of the air bearing table to replace the structural scheme of the eddy current displacement sensor (9) and the metal block (10) to measure the large-angle attitude angle of the three-axis air bearing table.

5. The measurement method of the triaxial air bearing table large-angle attitude angle measurement device based on the claims 1, 2 or 3 is characterized by comprising the following steps:

the method comprises the following steps: setting the rotation center O of the three-axis air bearing table₁Three-axis mechanical electric tracking rotary table rotation center O₂Mounting position R of eddy current displacement sensor₂Metal block mounting position R₁D is the installation error of the three-axis air bearing table and the rotation center of the three-axis mechanical electric tracking rotary table, the distance between a displacement sensor and a metal block on the three-axis air bearing table measured by an eddy current displacement sensor on the three-axis mechanical electric tracking rotary table in the initial state is l, and the position of the metal block after the movement of the three-axis air bearing table is determined by a₁Move to a₂Controlling a three-axis mechanical electric tracking turntable to enable the position of the eddy current displacement sensor to be b to be unchanged in order to ensure that the measured value l of the eddy current displacement sensor is unchanged₁Move to position b₂Setting a three-axis air bearing table motion angle a and a three-axis mechanical and electric tracking rotary table motion angle b;

step two: when d is 0, namely the rotation error is 0, the motion angle value of the three-axis air bearing table, namely a is b, can be determined by reading the motion angle b of the three-axis electric tracking rotary table, so that the attitude angle of the three-axis air bearing table is obtained, and the measurement accuracy of the angular position of the three-axis air bearing table only depends on the angular position accuracy of the three-axis mechanical electric tracking rotary table and the accuracy of the eddy current displacement sensor;

step three: when d is not 0, the intermediate variable x is set to a for derivation convenience by using the established geometric model₁To O₂Deducing the motion angle value a of the three-axis air bearing table and the motion angle values b and R of the three-axis mechanical electric turntable₁、R₂D, l and the intermediate variable x are as follows:

step four: knowing that the motion angle of the three-axis mechanical and electric tracking rotary table is b, solving an intermediate variable x of a nonlinear equation by using MATLAB according to an equation (1), substituting the value of x into an equation (2) to solve the motion angle a of the three-axis air bearing table, and calculating the magnitude of the attitude and angular position error (b-a) of the three-axis air bearing table;

step five: obtaining the influence of each relevant parameter on the angular position precision of the triaxial air bearing table:

(1) maintenance of R₁、R₂The error l is unchanged, the error of the attitude angular position of the three-axis air bearing table linearly increases along with the increase of the rotation error d, and the error (b-a) of the angular position increases along with the increase of the motion angle b of the three-axis mechanical and electric tracking rotary table;

(2) maintenance of R₁、R₂D is unchanged, and along with the increase of the distance l between the eddy current displacement sensor and the metal block, the error (b-a) of the attitude angle position of the three-axis air bearing table is reduced;

(3) keeping l and d unchanged, and following the installation radius R of the eddy current displacement sensor and the metal block₁、R₂The increasing angular position error (b-a) decreases therewith;

by utilizing the conclusion, the angular position error of the three-axis air bearing table can be reduced by increasing the installation radius of the eddy current displacement sensor and the metal block and increasing the installation distance between the eddy current displacement sensor and the metal block.

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