A method for achieving vertical rotation of the rotation axis under limited rotation angle conditions

Abstract

The present invention provides a method for realizing the vertical position of the rotary axis under limited rotation angle conditions, belonging to the field of rotary axis assembly measurement technology. When the inner frame of the inertial platform swings within the acute angle range due to the limit, the sensitive direction of the level meter and the inner frame are pointed to the +X axis direction; the inner frame is rotated, the level meter points to the +X axis +N° and -N° directions respectively, and the readings are x1 and x2 respectively, and the support of the outer frame axis system in the Y direction is repeatedly adjusted so that the value of the level meter in the +X axis ±N° direction is close to the average value #imgabs0#; then the inner frame is rotated so that the level meter points back to the +X axis direction, and the level meter rotates 90° so that the sensitive direction of the level meter points to the +Y axis direction; the support of the outer frame axis system in the X direction is repeatedly adjusted so that the value of the level meter in the +Y axis ±N° direction is close to the average value #imgabs1#; the rotary axis system reaches a vertical state with an accuracy of m arc seconds. The method of the present invention is simple and convenient, and is not limited by external structures and conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of rotary shaft system assembly measurement, and in particular relates to a method for realizing a rotary axis line being vertical to the earth under a limited rotation angle condition. Background Art

[0002] An inertial platform is a device that uses a gyroscope to keep the platform unchanged in inertial space, also known as a gyroscope stabilized platform. It is an important component in an inertial navigation system.

[0003] The inertial platform is generally a five-axis gimbal structure. The main structural parts are the base frame, outer frame, middle frame, inner frame, platform frame and redundant frame from outside to inside. The frames are connected by bearing bushings, bearings and shafts. From outside to inside, the axis systems are named outer frame axis system, middle frame axis system, inner frame axis system, platform axis system and redundant axis system. The frames rotate relative to each other through the axis system.

[0004] During the assembly and debugging of the inertial platform axis system, in order to measure the axis system inclination rotation accuracy of the frame structure, it is necessary to use a level to adjust the axis of rotation to the plumb ground. The usual adjustment method is to place the level above the axis of rotation, and the axis rotates one circle, and the level also rotates one circle. By fine-tuning the support of the outer frame axis system, the value change range of the level in each direction within one circle is less than a certain requirement. At this time, the inclination angle of the axis and the plumb state is less than the expected value.

[0005] However, in the actual assembly test of the inertial platform, some of the shaft system rotating parts have protruding parts, or due to the influence of the outer frame limit device, the inner frame will interfere with the outer frame during rotation, and the rotating axis can only swing within a certain small angle. At this time, the level cannot rotate with the axis to the required position to read the value, and it is impossible to know whether the rotation axis is plumb. For example, if it can only rotate ±15°, the above method of adjusting the plumb by rotating a full circle cannot be used.

[0006] In order to solve the above problem, a precision-machined surface on the outside of the rotating axis that is precisely perpendicular to the rotating axis can be set as the installation surface. A level is placed on this surface. By fine-tuning the support of the shaft system, the level value of this surface is monitored using the level until this surface reaches the ideal horizontal state. At this time, the rotation axis can be considered to be plumb. However, this method will introduce a verticality error between the machined installation surface and the axis.

[0007] If the rotation axis is to be accurately adjusted to plumb, the above method of adjusting the plumb with the help of the mounting surface has several specific problems: (1) the vertical error between the mounting surface and the rotation axis cannot be directly measured and eliminated; (2) some structures may not have a suitable area to process the mounting surface; (3) after the inertial platform is assembled, other components have been installed on the mounting surface outside the axis, and a spirit level cannot be placed; (4) when placing the spirit level, the center of gravity will be offset, causing the frame structure to tilt and deform, and introducing new measurement errors.

[0008] In summary, the solution of setting a mounting surface on the outside of the rotating shaft is not universally applicable and is limited by factors such as structure, precision and assembly process. Summary of the invention

[0009] The problem to be solved by the present invention is to provide a method for realizing a rotation axis being vertical to the earth under the condition of limited rotation angle.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for realizing the vertical position of the rotation axis to the ground under the condition of limited rotation angle, comprising the following steps:

[0011] S1. Set the outer frame rotation axis of the inertial platform rotation axis system as the Z axis of the rectangular coordinate system;

[0012] S2. When the inner frame swings within the acute angle range due to the limit, place the level at the top of the outer frame's rotation axis so that the level's sensitive direction points to the +X axis direction; at this time, the inner frame's position also points to the +X axis direction; when the rotation axis is perpendicular to the earth with an accuracy of m arc seconds, according to the limit deviation angle of the level's swing The relationship with the precision m arc seconds gives the deviation angle of the level from the extreme position of the X-axis or Y-axis. = ±N°, where N°<45°;

[0013] S3. Rotate the inner frame, and the level meter points to the +X axis +N° and -N° directions respectively, and the readings are x1 and x2 respectively. At this time, half of the difference between x1 and x2 is the pitch tilt angle of the rotation axis in the Y direction. Repeatedly adjust the Y-direction support of the outer frame axis system to make the level meter values ​​in the +X axis +N° and -N° directions close to the average value of x1 and x2. ;

[0014] S4. Rotate the inner frame to make the level point back to the +X axis direction, lift the level and rotate it 90° so that the sensitive direction of the level points to the +Y axis direction;

[0015] S5. Rotate the inner frame so that the level meter points to the +Y axis +N° and -N° directions respectively, and read y1 and y2; at this time, half of the difference between y1 and y2 is the roll tilt angle of the rotation axis in the X direction. Repeatedly adjust the X-direction support of the outer frame axis system to make the level meter values ​​in the +Y axis +N° and -N° directions close to the average value of y1 and y2. ;

[0016] S6. Repeat steps S1 to S5, and adjust the X and Y supports of the outer frame axis system repeatedly to make the level gauge close to +N° and -N° directions of the +X axis. , close to +N° and -N° directions on the +Y axis , at this time the rotating axis system reaches a plumb state with an accuracy of m arc seconds.

[0017] Furthermore, the level is a single-axis high-precision level.

[0018] When the accuracy of the rotary axis being perpendicular to the earth is required to be m arc seconds, the deviation angle of the level instrument is The maximum allowable error between the two extreme positions must be less than The rotation axis is perpendicular to the earth's surface, and the required accuracy is m arc seconds. The deviation angle from the swing limit position is The relationship is:

[0019]

[0020] Among them, the current measurement value is the real-time display value of the level; the minimum digital display position is the resolution value of the gear selected when the level is measured; θ is the deviation angle between the level and the extreme position of the X-axis or Y-axis; (1%×current measurement value+minimum digital display position) is the error value caused by the processing deviation of the level mounting seat to the level, and the arc second value corresponding to (1%×current measurement value+minimum digital display position)×minimum digital display position is the unit converted into arc seconds.

[0021] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0022] The present invention is different from the traditional method of using a spirit level to align the center of rotation axis to the earth in a full circle, and does not require the use of a reference plane perpendicular to the axis. Instead, it uses a high-precision spirit level to point to a non-sensitive direction. When the pointing angle changes slightly, a sinusoidal component change will occur in the sensitive direction, and the plumb angle of the axis is adjusted by using this tiny change value.

[0023] At the same time, the present invention can be used according to the limit deviation angle of the level instrument swing The relationship with the precision m arc seconds gives the deviation angle of the level from the extreme position of the X-axis or Y-axis. .

[0024] The method of the present invention is simple and convenient, is not limited by external structures and conditions, and has good application prospects in scientific research, production, installation and debugging of inertial systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation methods of the present invention will become more obvious. The contents shown in the accompanying drawings are only used to explain the present invention and do not constitute any limitation to the present invention in any sense. In the accompanying drawings:

[0026] Figure 1 It is a schematic diagram of placing the level of the present invention.

[0027] Figure 2 It is a schematic diagram of the measuring direction of the level meter of the present invention.

[0028] In the figure:

[0029] 1. Outer frame; 2. Inner frame; 3. Level mounting base; 4. Level. DETAILED DESCRIPTION

[0030] like Figure 1 and Figure 2 As shown, the present invention provides a method for realizing a rotation axis vertical to the earth under limited rotation angle conditions, comprising the following steps:

[0031] S1, setting the rotation axis of the outer frame 1 of the inertial platform rotation axis system to the Z axis of the rectangular coordinate system;

[0032] S2. When the inner frame 2 can only swing within a range of 30° due to the limit, the level 4 is placed at the top of the rotation axis of the outer frame 1, connected to the inner frame 2 through the level mounting seat 3, and can rotate with the inner frame 2, so that the sensitive direction of the level 4 points to the +X axis direction; at this time, the position of the inner frame 2 is also pointing to the +X axis direction;

[0033] When the accuracy of the rotation axis being perpendicular to the earth is required to be 2 arc seconds, the deviation angle of the swing of the level 4 is The maximum allowable error between the two extreme positions must be less than Arc seconds, the accuracy of the vertical axis of rotation is 2 arc seconds, and the deviation angle from the swing limit position The relationship is:

[0034]

[0035] Among them, the current measurement value is the real-time display value of the level 4. When the "0" position of the level 4 is accurate, its display value depends on the plumb state of the axis and the processing and installation accuracy of the level mounting seat 3; the component caused by the plumb state of the axis will decrease until it is ignored as the axis deviates from the plumb angle. The processing, installation accuracy, and shape and position accuracy of the level mounting seat 3 can be controlled within 0.002mm. Calculated based on the base length of the level 4 of 100mm, it is equivalent to a measurement value of 20 after conversion. The minimum digital display position is the resolution value of the gear selected when the level 4 is measured. When the level 4 selects the 1μm / m gear, the minimum digital display position is 1, that is, the minimum resolution is 1, and the corresponding number of arc seconds is 0.2 arc seconds.

[0036] When the accuracy of the rotation axis being perpendicular to the earth is required to be 2 arc seconds, then:

[0037]

[0038] The solution is: =9.77°

[0039] Among them, (1%×20+1) is the error value caused by the processing deviation of the level mounting base 3 to the level 4, and the purpose of multiplying it by 0.2 is to convert the unit into arc seconds.

[0040] From the above calculation, we can know that when When the angle is greater than 9.77°, the accuracy of the rotation axis being perpendicular to the earth can be within 2 arc seconds.

[0041] S3, rotate the inner frame 2, the deviation angle of the swing =±9.77°, the level 4 points to the +X axis +9.77° and -9.77° directions respectively, and the readings are x1 and x2 respectively. At this time, half of the difference between x1 and x2 is the pitch tilt angle of the rotation axis in the Y direction. Repeatedly adjust the support of the outer frame axis system in the Y direction to make the values ​​of the level 4 in the +X axis +9.77° and -9.77° directions close to the average value of x1 and x2 ;

[0042] S4, rotate the inner frame 2 so that the level 4 points back to the +X axis direction, lift the level 4 and rotate it 90° so that the sensitive direction of the level 4 points to the +Y axis direction;

[0043] S5. Rotate the inner frame 2 to make the level 4 point to the +Y axis +9.77° and -9.77° directions respectively, and read y1 and y2; at this time, half of the difference between y1 and y2 is the roll tilt angle of the rotation axis in the X direction. Repeatedly adjust the support of the outer frame axis system in the X direction to make the values ​​of the level 4 in the +Y axis +9.77° and -9.77° directions close to the average value of y1 and y2. ;

[0044] S6, repeat steps S2 to S5, repeatedly adjust the X and Y supports of the outer frame axis system, so that the level 4 is close to +9.77° and -9.77° directions of the +X axis. , close to +9.77° and -9.77° on the +Y axis , at this time the rotating axis system reaches a plumb state with an accuracy of m arc seconds.

[0045] Wherein, the level 4 is a single-axis high-precision level.

[0046] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for achieving a rotation axis vertical to the earth under limited rotation angle conditions, characterized in that: The steps include: S1. Set the outer frame rotation axis of the inertial platform rotation axis system as the Z axis of the rectangular coordinate system; S2. When the inner frame swings within the acute angle range due to the limit, place the level at the top of the outer frame's rotation axis so that the level's sensitive direction points to the +X axis direction; at this time, the inner frame's position also points to the +X axis direction; when the rotation axis is perpendicular to the earth with an accuracy of m arc seconds, according to the limit deviation angle of the level's swing The relationship with the precision m arc seconds gives the deviation angle of the level from the extreme position of the X-axis or Y-axis. = ±N°, where N°<45°; S3. Rotate the inner frame, and the level meter points to the +X axis +N° and -N° directions respectively, and the readings are x1 and x2 respectively. At this time, half of the difference between x1 and x2 is the pitch tilt angle of the rotation axis in the Y direction. Repeatedly adjust the Y-direction support of the outer frame axis system to make the level meter values ​​in the +X axis +N° and -N° directions close to the average value of x1 and x2. ; S4. Rotate the inner frame to make the level point back to the +X axis direction, lift the level and rotate it 90° so that the sensitive direction of the level points to the +Y axis direction; S5. Rotate the inner frame so that the level meter points to the +Y axis +N° and -N° directions respectively, and the readings are y1 and y2 respectively; at this time, half of the difference between y1 and y2 is the roll tilt angle of the rotation axis in the X direction. Repeatedly adjust the X-direction support of the outer frame axis system to make the level meter's values ​​in the +Y axis +N° and -N° directions close to the average value of y1 and y2. ; S6. Repeat steps S1 to S5, and adjust the X and Y supports of the outer frame axis system repeatedly to make the level gauge close to +N° and -N° directions of the +X axis. , close to +N° and -N° directions on the +Y axis , at this time, the rotating axis system reaches a plumb state with an accuracy of m arc seconds; The resolution value of the gear selected when the level meter is measuring is the minimum digital display position; When the accuracy of the rotary axis being perpendicular to the earth is required to be m arc seconds, the deviation angle of the level instrument is The maximum allowable error between the two extreme positions is arc seconds; When the accuracy of the rotary axis being perpendicular to the earth is required to be m arc seconds, the limit deviation angle of the level instrument is The relationship with the precision m arc seconds is: Among them, the current measurement value is the real-time display value of the level; (1%×current measurement value+minimum digital display position) is the error value caused by the processing deviation of the level mounting seat to the level; (1%×current measurement value+minimum digital display position)×the arc second value corresponding to the minimum digital display position is the unit converted into arc seconds.

2. The method for achieving a rotation axis vertical to the earth under limited rotation angle conditions according to claim 1, characterized in that: The level is a single-axis high-precision level.

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