CN105423957A - Rotation shaft rotation angle measuring method restraining shafting dip angle rotation error - Google Patents

Abstract

The invention belongs to the field of optical measurement, and relates to a rotation shaft rotation angle measuring method restraining shafting dip angle rotation error. The measuring principle system of the invention is shown in figure 1. A rotation shaft (2) with an optical wedge (5) is placed between an auto-collimator (1) and a mirror (3). Due to refraction of the optical wedge (5), a reflected light beam, which is generated after the light beam emitted by the auto-collimator (1) passes through the mirror (3) and is reflected back, forms a deflection angle Beta with the outgoing light beam, returns to the auto-collimator (1) and converges into a light spot image; when the rotation shaft (2) and the optical wedge (5) rotate as a whole, the reflected light beam rotates about the axis of the rotation shaft (2), and the light spot image in the auto-collimator (1) moves along a circular trajectory; and a computer (4) records the coordinates of the center of mass of the light spot image on the circumference, fits out the coordinates of the center of the trajectory circle, specifies the start point A and the end point B on the circumference, and works out the corresponding center-of-circle opening angle based on the coordinate values of A and B, wherein the angle is the rotation angle of the rotation shaft (2) from A to B needing to be measured. In the invention, the shafting dip angle rotation error has almost no effect on the measurement accuracy of rotation angle.

Description

A method for measuring the rotation angle of the shaft to suppress the inclination angle rotation error of the shaft system

technical field

The invention belongs to the field of optical-mechanical detection, and is a high-precision method for measuring the rotation angle of a rotating shaft. The invention relates to a combination of an autocollimator, an optical wedge and a reflector, specifically a method for measuring the rotational angle of a rotating shaft that suppresses the rotational error of the inclination angle of the shaft system.

Background technique

According to the angle measurement principle of the autocollimator, it is easy to think of using the optical system shown in Figure 1 to measure the rotation angle of the rotating shaft. Among them, 1 is an autocollimator, 2 is a rotating shaft, 3 is a mirror, and 4 is a computer; the mirror 3 is installed on the end face of the rotating shaft 2, and forms an angle θ with the end face of the rotating shaft 2; After the light beam is reflected by the reflector 3, it is deflected at an angle β=2θ relative to the outgoing beam of the autocollimator 1, and enters the autocollimator 1 to form a spot image; the autocollimator 1 is connected with the computer 4, and the autocollimator The position data of the spot image obtained in the instrument 1 is read by the computer 4, and the position coordinates of the spot image can be obtained through processing, and displayed on the display screen of the computer 4; when the rotating shaft 2 and the mirror 3 rotate integrally, The reflected light beam rotates around the axis of the rotating shaft 2, and the light spot image in the autocollimator 1 moves along a circular track on the display screen of the computer 4, as shown in Figure 2, the radius of the track circle depends on the reflected light beam and the outgoing light beam The deflection angle β=2θ, and the relative distance between the autocollimator 1 and the reflector 3; a Cartesian coordinate system is established with any light point image position on the lower left on the trajectory circle as the origin, and a series of values obtained during the rotation of the recording shaft 2 The coordinates of the circle points can be used to fit the coordinates of the center of the trajectory circle C, and then use the coordinate values of the sampling start point A and end point B on the circle to calculate the center opening angle corresponding to the arc between A and B This angle is the rotation angle of the rotating shaft 2 .

The measurement method is simple and convenient, and can realize the measurement of the rotation angle in a large range at the same time, and can be widely used in the measurement of the rotation error of the mechanism. However, due to the machining error of the shaft, the installation error of the bearing, the clearance of the bearing itself, and the transmission force of the shaft during use, the swing occurs during the rotation of the shaft, which is professionally called the shaft system inclination rotation. The error, which causes the reflected light beam on the mirror 3 to swing, causes the light point image in the autocollimator 1 to deviate from the ideal circular track, and the deviation is twice the error of the axis tilt angle rotation, so that the end position changes from B point changes to point B1, as shown in Figure 2, resulting in an error in the measurement of the rotation angle The inclination angle rotation error of the shaft system in different rotating mechanisms is different, generally ranging from a few arc seconds to tens of arc seconds. It can be seen that the inclination angle rotation error of the shaft system seriously affects the measurement accuracy of the rotation angle of the shaft 2.

The content of the present invention is a method for measuring the rotation angle of a rotating shaft that suppresses the inclination angle rotation error of the shaft system.

In order to clearly illustrate the content of the present invention, the working principle of the autocollimator 1 will be described in detail below. The internal optical structure of autocollimator 1 is shown in the dotted line frame among Fig. 3, and wherein 11 is parallel light source, and 12 is beam splitter, and 13 is lens, and 14 is CCD; Beamer 12 is emitted from the center of the light outlet at a bending angle of 90°, reflected by reflector 3 to form an angle β with the outgoing beam, and sequentially passes through beam splitter 12 and lens 13 to converge on the panel of CCD14 to form a spot image; CCD14 and computer 4 directly connected, the position data of the light point image on the CCD14 panel is read by the computer 4, and the position coordinates of the light point image can be obtained through the program processing in the computer 4, and displayed on the display screen of the computer 4.

Contents of the invention

Aiming at the influence of the shaft system inclination angle rotation error on the measurement of the rotation shaft rotation angle, the present invention proposes a method for measuring the rotation shaft rotation angle based on optical wedge refraction.

The schematic diagram of the measurement optical path system of the present invention is shown in Figure 4, wherein 1 is an autocollimator, 2 is a rotating shaft, 3 is a mirror, 4 is a computer, and 5 is an optical wedge; the optical wedge 5 is fixed on the end face of the rotating shaft 2, After the mirror 3 is placed on the shaft 2, it is vertically fixed, and the normal of the mirror 3 is parallel to the axis of the shaft 2; the shaft 2 with the optical wedge 5 is placed between the autocollimator 1 and the mirror 3. The beam emitted by the autocollimator 1 passes through the refraction of the optical wedge 5 and the reflection of the mirror 3 in sequence, and the reflected beam is then refracted by the optical wedge 5, forms a deflection angle β with the outgoing beam of the autocollimator 1, and returns to the autocollimator 1, and converge into a spot image; due to the refraction of the optical wedge 5, when the shaft 2 and the wedge 5 rotate together, the reflected light beam rotates around the axis of the shaft 2, and the spot image in the autocollimator 1 moves along the Circular track motion; the computer 4 records the coordinates of the center of mass of a series of light spots evenly distributed on the circumference obtained after the rotating shaft 2 rotates a circle, and fits out the coordinates of the center of the track circle, and then specifies the starting point A and the end point on the circumference according to the specific measurement requirements B, use the coordinate values of A and B to calculate the center opening angle corresponding to the arc between A and B This angle is the rotation angle of the rotating shaft 2 from A to B to be measured.

There are three programs stored in the computer 4 connected to the autocollimator 1: program I is used to calculate the coordinates of the center of mass of the light point image, and display the position of the light point image and the coordinates of the center of mass of the light point image on the display; program II is used to drive the rotating shaft 2 It rotates in two modes, one is continuous rotation, the other is intermittent rotation with a certain step length, and in addition, it stores a series of coordinates of the center of mass of the light point images obtained after the rotating shaft 2 intermittently rotates for a week; program III obtains the coordinates of the center of mass after rotating the shaft 2 intermittently for a week based on the import The trajectory circle and its center coordinates are fitted by a series of coordinate values, and the center opening angle corresponding to the arc between two points is calculated based on the coordinate values of any two points on the trajectory circle.

In order to ensure the measurement accuracy of the rotation angle of the rotation axis 2, the optical path design of the measurement system needs to make the trajectory circle of the light point image only slightly smaller than the measurement field of view of the autocollimator 1. parallel to the axis of the reflector 3 and parallel to the normal of the reflector 3, so that the center of the trajectory circle is basically the center of the field of view of the autocollimator 1, and the wedge angle of the optical wedge 5 is adjustable so that the autocollimator After the distance between 1 and reflector 3 is determined under the limited space conditions, the diameter of the trajectory circle can be made close to the diameter of the field of view of the autocollimator 1 by adjusting the wedge angle of the optical wedge 5 .

In the method of the present invention, although the inclination angle rotation error of the shaft system will cause the optical wedge 5 to swing when the rotating shaft 2 rotates, due to the transmission characteristics of the optical wedge 5, the light beam incident on the optical wedge 5 and the light emitted from the optical wedge 5 in the reflected light path The light beam hardly moves with it, especially the deflection angle β between the two hardly changes, that is, the inclination angle rotation error of the shaft system will hardly cause the spot image on the CCD panel to move away from the track circle, thereby improving the rotation angle of the shaft 2 measurement accuracy.

The ability of the present invention to suppress the inclination rotation error of the shaft system will be described in detail below. Assume that the rotation error of the inclination angle of the shaft system is α ₁ , the wedge angle of the optical wedge 5 is γ, the refractive index is n, and it is set as a right-angle optical wedge for the convenience of analysis. As shown in Figure 5, under the action of α ₁ , the optical wedge 5 and its normal also swing α ₁ , resulting in a series of refraction angles at each interface passing through the optical wedge 5 in the outgoing light path from the autocollimator 1 to the mirror 3 α ₂ , α ₃ , α ₄ , and a series of refraction angles β ₁ , β ₂ , β ₃ , β ₄ are also generated in the reflected light path from the mirror 3 to the autocollimator 1, and finally the exit wedge 5 in the reflected light path The light beam and the outgoing beam of the autocollimator 1 form an included angle Δβ+β=β ₄ −α ₁ , where Δβ is the error amount of the deflection angle β caused by the rotation error of the inclination angle of the shaft system. The smaller the Δβ, the stronger the ability of the present invention to suppress the inclination angle rotation error of the shaft system.

According to the refraction relationship of light, the following equation is obtained:

Δβ+β=β ₄ -α ₁ (1)

$\frac{{\mathrm{<span\; class="notranslate">\; sin\&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; sin\&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; sin\&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}{{\mathrm{<span\; class="notranslate">\; sin\&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; sin\&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; sin\&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; sin\&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}{{\mathrm{<span\; class="notranslate">\; sin\&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

α ₃ =α ₂ +γ(3)

β ₃ =β ₂ -γ(4)

-β ₁ +γ=α ₄ -γ(5)

Considering the wedge angle γ and the refractive index n as known quantities, Δβ can be expressed as _a function of α1 by using the above equation. When setting γ = 1800 arc seconds, n = 1.5, and α ₁ = 0 arc seconds, the deflection angle β = 1800 arc seconds can be calculated; when the shaft system inclination angle rotation error α ₁ changes in the range of 0 arc seconds to 100 arc seconds, Figure ₆ shows the relationship curve between calculated Δβ and shaft system inclination angle rotation error α1.

It can be seen from Fig. 6 that the error amount Δβ of the deflection angle β is approximately linear with the inclination rotation error α ₁ of the shaft system, and the slope is 4×10 ^-5 , that is, the error of the deflection angle β is less than 1/10000 of the inclination rotation error of the shaft system. It can be seen that the present invention can effectively suppress the influence of the inclination angle rotation error of the shaft system on the running track of the light point image, and improve the measurement accuracy of the rotation angle of the rotating shaft.

Description of drawings

FIG. 1 is an optical system for measuring the rotation angle of a rotating shaft described in the background art. Wherein 1 is an autocollimator, 2 is a rotating shaft, 3 is a mirror, and 4 is a computer.

Figure 2 is the basic principle of measuring the rotation angle of the rotating shaft and the analysis diagram of the measurement error. When the rotating shaft 2 rotates, the light point image moves on the panel of CCD14 in the autocollimator 1 to form a trajectory circle, and the rectangular coordinate system is established with any position of the light point image on the trajectory circle as the origin, and the series of circular point coordinates obtained according to the test You can fit the center coordinate C of the trajectory circle, and then use the coordinate values of the test start point A and end point B on the circle to calculate the center opening angle corresponding to the arc between A and B This angle is the rotation angle of the rotating shaft 2 . Due to the existence of the shaft system inclination angle rotation error, the rotation angle measurement has measurement error.

FIG. 3 is a schematic diagram showing the internal optical structure of the autocollimator 1 . Wherein 11 is a parallel light source, 12 is a beam splitter, 13 is a lens, and 14 is a CCD.

FIG. 4 is an optical system for measuring the rotation angle of a rotating shaft proposed in the present invention. 5 is an optical wedge fixed on the end surface of the rotating shaft 2, and the mirror 3 is fixed vertically after being placed on the optical wedge 5. The function of the optical wedge 5 is to deflect the beam emitted from the autocollimator 1, so that the point image still moves along a circular trajectory when the rotating shaft 2 rotates. Due to the transmission characteristics of the optical wedge 5, the rotation error of the inclination angle of the shaft system will hardly cause the light spot image to move away from the track circle, thereby improving the measurement accuracy of the rotation angle of the rotating shaft 2 .

Fig. 5 is a schematic diagram of the influence of the shaft system inclination angle rotation error on the deflection angle β in the present invention. Among them, α ₁ is the rotation error of the inclination angle of the shaft system, which causes a series of refraction angles α ₂ , α ₃ , and α ₄ to be generated at each interface of the optical wedge 5 in the outgoing light path from the autocollimator 1 to the reflector 3, and from the reflector 3 3 also produces a series of refraction angles β ₁ , β ₂ , β ₃ , β ₄ in the reflected light path of the autocollimator 1, Δβ is the error amount of the deflection angle β caused by α ₁ , and the optical wedge 5 is the wedge angle γ, A right-angled wedge of refractive index n.

Fig. 6 is the relationship curve between the shaft system inclination angle rotation error α ₁ and the deflection angle error Δβ in the present invention.

Fig. 7 is the rotation track circle of the rotating shaft 2 in the worm gear mechanism measured by the two methods of the present invention and the background technology, and the rotating shaft 2 is measured every 4.5 degrees. Wherein "+" is the measured point of the present invention, and "o" is the measured point of the background technology.

Fig. 8 is the measurement error of the angle of rotation of shaft 2 in the worm gear mechanism of the present invention and the background technology obtained by processing the data in Fig. 7, wherein "+" is the data point of the present invention, and "o" is the data point of the background technology. When the rotation step of the rotating shaft 2 is 4.5 degrees, the maximum absolute errors are 0.05 degrees and 1.45 degrees, and the maximum relative errors are 1% and 30%, respectively.

detailed description

1) Autocollimator 1 is CollapexAC300, a product of Xi'an Angke Spot Technology Co., Ltd., with an effective aperture of 32mm, a focal length of 300mm, and an imaging field of view of 50 arc minutes;

2) The rotating shaft 2 is a hollow rotating shaft fixed with the worm wheel in the worm gear mechanism, driven by a servo motor, and the servo motor is connected with the computer 4;

3) the computer 4 that links to each other with autocollimator 1 is the incidental equipment of autocollimator 1, and the program 1 that producer is given is installed on it, and the function of program 1 is: provide main interface on the display screen of computer 4, The position of the spot image is displayed on the main interface as a reticle, the center of the reticle is located at the centroid of the spot image, and the reticle moves synchronously with the position of the spot image; establish a Cartesian coordinate system and move along the display The horizontal direction of the screen is the x-axis, and the vertical direction of the display screen is the y-axis. The units are arc seconds. There is a function box of "Set Origin" on the main interface. The operator selects a position where the cross mark moves to as the "current Position", input "current position" in the function box of "set origin", this position is the origin of the Cartesian coordinate system; follow the position of the cross reticle to calculate and display the coordinates (x, y) of the center of mass of the light spot image, And the coordinates of the test points can be stored in the computer 4 according to the needs of the operator;

4) Optical wedge 5 is a double optical wedge compensator with adjustable wedge angle. The product GCO-030211M of Daheng Optoelectronics Co., Ltd. has a wedge angle adjustment range of 0 to 1 degree, a refractive index of 1.5 at a wavelength of 589nm, and an effective aperture of 25mm. ;

5) The light aperture of the reflector 3 is 25 mm, and the base of the fixed reflector 3 has an adjustment mechanism for adjusting its pitch and azimuth angle;

6) The self-edited program II is input into the computer 4, and the program II controls the rotation of the rotating shaft 2: start, stop, rotation speed, continuous rotation mode, and intermittent rotation mode with a rotation step size of 4.5 degrees;

7) The self-edited program III is input into the computer 4, and the coordinates of a series of test points in which the rotating shaft 2 stored in the program I has been rotated for one week are imported into the program III in order, and the program III fits the trajectory circle, and calculates the coordinates of the center of the circle, And convert the coordinates of the center of the circle as the new origin to convert the coordinates of all test points distributed on the trajectory circle relative to the new origin; calculate the rotation angle between any two test points on the trajectory circle according to the operator's requirements;

8) At first use the method introduced in the background technology to build the measurement system according to Fig. 1; the mirror 3 is fixed on the end face of the rotating shaft 2, and calculates according to the parameters of the autocollimator 1: the inclination angle θ of the mirror 3 relative to the end face of the rotating shaft 2 is 11 arc minutes, the distance between the light outlet of the autocollimator 1 and the reflector 3 is equal to 2.1 meters; build the optical path according to these two calculation parameters; turn on the autocollimator 1, computer 4 and program I to make the light spot The image enters the field of view of the autocollimator 1, that is, the reticle appears on the main display interface of the computer 4; start the program II to drive the rotating shaft 2 to rotate continuously, and observe the movement track of the reticle on the main display interface of the computer 4 circle, and fine-tune the position of the autocollimator 1 until the trajectory circle is located at the central symmetrical position of the display frame of the main interface, so that the optical axis of the light emitted by the autocollimator 1 is parallel to the axis of the rotating shaft 2; then fine-tune the reflector The included angle θ between 3 and the end surface of the rotating shaft 2 is to drive the rotating shaft 2 to rotate again until the trajectory circle of the reticle movement is slightly smaller than the field of view of the autocollimator 1, which is basically the inscribed circle of the display frame of the main interface ; Make the reticle stay at the bottom left of the trajectory circle, and set it as the origin; program II drives the rotating shaft 2 to rotate intermittently with a step length of 4.5 degrees, and at the same time, program I stores the center coordinate value of the reticle at each step. After a week, stop the rotation of the shaft 2; import the measured coordinates of a series of test points into the program III in sequence, and fit the trajectory circle, as shown in Figure 7, where "o" represents the above-mentioned technology that is used Background technology The test point obtained by the method, the coordinates of the center of the track circle are (1177.13″, 875.06″), and the coordinates of the test point in the figure are relative coordinates with the center coordinates of the track circle as the new origin; deviation, and the distribution is not uniform enough; the center angle corresponding to each step can be calculated by using the coordinates of two adjacent test points, and this angle is the angle that the rotating shaft 2 rotates in each step measured by the method of the background technology. Make a difference between this value and the step length of the corner, and the error curve is as shown in the curve connected by "o" in Figure 8. The maximum absolute error relative to the 4.5-degree corner is 1.45 degrees, and the maximum relative error is 30%;

9) Use the method of the present invention to build a measurement system according to Fig. 4; based on the measurement system built in step "8)", remove the reflector 3 from the rotating shaft 2, and fix the optical wedge 5 with adjustable wedge angle to the end face of the rotating shaft 2 Above; according to the parameters of the optical path in Figure 4, the distance between the light outlet of the autocollimator 1 and the reflector 3 is calculated to be 2.1 meters, and the wedge angle of the optical wedge 5 is 25 arc minutes; after the reflector 3 is moved to the rotating shaft 2, it is as compact as possible place, vertically fixed on the optical table, and make the normal line of the mirror 3 parallel to the axis of the rotating shaft 2; move the autocollimator 1 so that the distance between it and the mirror 3 is 2.1 meters, and keep the autocollimation The optical axis of the instrument 1 is parallel to the rotating shaft 2, and the wedge angle of the optical wedge 5 is adjusted to 25 arc minutes; the program II is started to drive the rotating shaft 2 to rotate continuously, and the track circle of the cross reticle movement on the display main interface of the computer 4 is observed, and Finely adjust the position of the autocollimator 1 until the trajectory circle is located at the central symmetrical position of the display frame on the main interface, so that the optical axis of the light emitted by the autocollimator 1 is parallel to the axis of the rotating shaft 2; then fine-tune the wedge angle of the optical wedge 5 , drive the rotating shaft 2 to rotate continuously until the trajectory circle of the reticle movement is slightly smaller than the field of view of the autocollimator 1, which is basically the inscribed circle of the display frame of the main interface; use the value set in step "8)" Origin; program II drives the rotating shaft 2 to rotate intermittently with a step length of 4.5 degrees, and at the same time, program I stores the center coordinate value of the cross reticle at each step. The coordinates of a series of test points are imported in the program III in order, and the trajectory circle is fitted, as shown in Figure 7, wherein "+" represents the test point obtained with the method of the present invention, and its trajectory circle center coordinates are (1152.68 ", 909.12 " ), the trajectory circle basically coincides with the trajectory circle obtained in step "8)", and the coordinates of the test points in the figure are also relative coordinate values with the center coordinates of the trajectory circle as the origin; the test point "+" basically falls on the fitted trajectory circle above, and evenly distributed; the coordinates of the two test points represented by the adjacent "+" can be used to calculate the central angle corresponding to each step, and this angle is the rotation of the rotating shaft 2 per step measured by the method of the present invention. The difference between this value and the step length of the corner is calculated to obtain the error curve as shown in Fig. 8, the curve connected by "+", the maximum absolute error is 0.05 degrees relative to the 4.5 degree corner, and the maximum relative error is 1%.

Comparing the measurement errors of the two methods of the present invention and the background technology, it shows that the present invention can well suppress the influence of the shaft system inclination angle rotation error on the measurement result, and the measurement accuracy of the rotating shaft angle is very high.

Claims (2)

1. A method for measuring the rotating shaft angle of rotation that suppresses the inclination angle of the shaft system is characterized in that it is a method for measuring the rotating shaft angle based on optical wedge refraction, and the optical system for measuring the rotating shaft angle consists of an autocollimator (1), a rotating shaft (2 ), a reflector (3), a computer (4) and an optical wedge (5), the autocollimator (1) is connected to the computer (4); the optical wedge (5) is fixed on the end face of the rotating shaft (2), and the reflector (3) After being placed on the rotating shaft (2), it is vertically fixed, and the normal line of the mirror (3) is parallel to the axis of the rotating shaft (2); the rotating shaft (2) with the optical wedge (5) is placed on the self-collimating Between the instrument (1) and the reflector (3); the light beam emitted by the autocollimator (1) passes through the refraction of the optical wedge (5) and the reflection of the reflector (3) in turn, and the reflected beam passes through the optical wedge (5) The refraction, and the outgoing beam of the autocollimator (1) form a deflection angle β to return to the autocollimator (1), and converge into a light point image; when the rotating shaft (2) and the optical wedge (5) rotate together, the reflection The light beam rotates around the axis of the rotating shaft (2), and the light point image in the autocollimator (1) moves along a circular trajectory; the computer (4) records a series of images evenly distributed on the circumference of the circle obtained after the rotating shaft (2) rotates once. The coordinates of the center of mass of the light spot on the image, the coordinates of the center of the trajectory circle are fitted, and then the coordinates of any starting point A and end point B on the circle are used to calculate the center opening angle φ _i corresponding to the arc between A and B. The angle is is the rotation angle of the rotating shaft (2) from A to B; There are three programs stored in the computer (4): program I is used to calculate the coordinates of the center of mass of the light spot image, and displays the position of the light spot image and the coordinates of the center of mass thereof on the display screen; program II is used to drive the rotating shaft (2) in two modes Rotation, one is continuous rotation, and the other is intermittent rotation with a certain step length. In addition, a series of coordinates of the center of mass of the light point images obtained after the rotating shaft (2) is intermittently rotated for one cycle are stored; program III is obtained after the imported rotating shaft (2) is intermittently rotated for one cycle. A series of coordinate values to fit the trajectory circle and its center coordinates, and calculate the center opening angle corresponding to the arc between the two points based on the coordinate values of any two points on the trajectory circle; In order to ensure the measurement accuracy of the rotation angle of the rotating shaft (2), the optical path design of the measurement system needs to make the trajectory circle of the light point image only slightly smaller than the measurement field of view of the autocollimator (1). Therefore, the output of the autocollimator (1) The optical axis of the emitted light is parallel to the axis of the rotating shaft (2) and parallel to the normal of the reflector (3), so that the center of the trajectory circle is basically the center of the field of view of the autocollimator (1). In addition, the optical wedge The wedge angle of (5) is adjustable, so that after the distance between the autocollimator (1) and the reflector (3) is determined under space-limited conditions, the diameter of the trajectory circle and the autocollimator can be adjusted by adjusting the wedge angle of the optical wedge (5). The field of view diameter of the collimator (1) is close to. 2. a kind of measuring method of the shaft rotation angle that suppresses shafting inclination angle rotation error according to claim 1 is characterized in that: The autocollimator (1) has an effective diameter of 32mm, a focal length of 300mm, and an imaging field of view of 50 arc minutes; The optical wedge (5) is a double optical wedge compensator with an adjustable wedge angle, the adjustment range of the wedge angle is 0-1 degree, the refractive index is 1.5 at a wavelength of 589nm, and the effective aperture is 25mm; The light aperture of the reflector (3) is 25mm, and the base of the fixed reflector (3) has an adjustment mechanism for adjusting its pitch and azimuth angle; Said program II controls the rotation of the rotating shaft (2): start, stop, rotation speed, continuous rotation mode, intermittent rotation mode with a rotation step size of 4.5 degrees; The procedure III uses the coordinates of two adjacent test points to calculate the central angle corresponding to each step, and makes a difference between this value and the corner step to obtain the error curve, and obtains the maximum absolute error relative to the 4.5-degree corner 0.05 degrees, the maximum relative error is 1%.