CN106767558A - A kind of decoupled identification method of guide rail basal plane straightness error - Google Patents

Abstract

The invention discloses a decoupling identification method for the straightness error of the base surface of the guide rail, which uses a laser interferometer to measure the straightness error and angle error when the standard gauge block slides and the display error measured by the laser displacement sensor, and based on the rotation Quantitative theory expresses the movement of each part, and finally calculates the straightness error value of the base surface of the guide rail through the data processing method of error decoupling, so as to realize the purpose of measuring the straightness error of the base surface of the precision guide rail, which has the advantages of accuracy and certain feasibility It can be used in the research of CNC machine tool production quality detection analysis or machine tool precision analysis.

Description

A decoupling identification method for straightness error of guide rail base surface

technical field

The invention belongs to the field of geometric error research of numerical control machine tools, and more specifically relates to a decoupling identification method for the straightness error of a base surface of a guide rail.

Background technique

At present, the instruments and tools for measuring the geometric error of machine tools mainly include laser interferometer, measuring ruler, level meter, collimator and dial gauge, etc. Laser interferometer is mainly used to measure the positioning error, straightness, angle error, Verticality, etc., but it is rarely used in the measurement of assembly rails, because its measurement is time-consuming and costly, and the use of traditional measurement tools can meet the requirements. The spirit level and dial indicator can be used to measure the straightness and angle in the guide rail assembly, and use the measurement results as a standard to adjust the assembly or scrape the base surface of the guide rail. The collimator is suitable for quickly measuring the straightness error of the assembled guide rail in the factory, with high efficiency and convenient use.

In 2001, Japanese scholar Eiji Shamoto and others used interferometer measurement to build a measurement experiment platform for hydraulic guide rail pairs, and used finite element analysis to study the influence of oil film thickness and force on the straightness of guide rails in hydraulic guide rails. In 2007, Canadian scholar T.O.Ekinci et al. studied the relationship between the angular error and the straightness error on the guide rail slider. They used a scale and a laser interferometer to build an experimental platform to study the relationship between the distance between the two sliders and the guide rail. Quantitative relationship of the wavelength ratio of the basal profile. In 2016, Jun Zha of Xi'an Jiaotong University further considered the static model to analyze the straightness accuracy of the hydraulic guide rail, and used the laser interferometer to measure the data for verification. Most of the previous studies considered the relationship between the straightness error of the guide rail slider, and a lot of research was done, but the measurement of the straightness error of the base surface of the guide rail itself was not discussed in detail.

For the straightness measurement of the base surface of the guide rail, most of the machine tool factories currently use dial gauges and level gauges, which are not accurate and will introduce other unnecessary errors. In view of the existing problems, in order to study the method of measuring the straightness of the guide rail base surface with high precision, it is necessary to propose a reasonable test method under the current conditions, and give a decoupling identification method for the straightness error measurement of the guide rail base surface.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a method for accurately identifying the straightness error of the base surface of the machine tool guide rail. The technical problem that the straightness error of the base surface is difficult to accurately measure and obtain.

In order to achieve the above object, the present invention proposes a decoupling identification method for the straightness error of the base surface of the guide rail, which includes the following steps:

(1) Build a measurement platform:

Install the laser head of the laser interferometer on the side of the guide rail to be measured, the laser interferometer reflector is installed on the top of the standard gauge block and set towards the laser head, and the laser displacement sensor is installed on the standard gauge block and located on the back side of the standard gauge block; Place the standard gauge block flat on the base surface of the guide rail to be measured;

(2) Measure and obtain initial parameters:

Make the standard gauge block close to the surface to be measured on the guide rail, move the standard gauge block, and record the measurement result of the laser interferometer and the measurement result of the laser displacement sensor y _lx at each position; the measurement result of the laser interferometer includes the movement of the standard gauge block The pitch angle deviation ε _zx , the roll angle deviation ε _xx , and the comprehensive straightness error δ _ysx in the angular deviation at the time; the starting point indication of the laser displacement sensor y _lx0 ;

(3) Error data processing:

Take the initial position _p0 of the measurement point P on the mirror as the zero point of the global coordinate system, the forward direction of the standard gauge block is the X axis, and the vertical upward is the Y axis, and the Z axis is determined by the right-hand rule;

According to the comprehensive straightness error δ _ysx of the mirror measured by the laser interferometer, the straightness deviation δ _yx of a certain point on the standard gauge block is derived; according to the derived δ _yx and the measured ε _zx , ε _xx establishes the motion model of the laser displacement sensor, and then obtains the straightness deviation δ _ylx of the laser displacement sensor;

According to the measurement result y _lx of the laser displacement sensor, the starting point indication y _lx0 of the laser displacement sensor and the straightness deviation δ _ylx of the laser displacement sensor, the straightness error δ _ygx of the base surface of the guide rail is calculated.

Further, the specific data processing process of step (3) is as follows:

The measurement point on the laser interferometer mirror is P, its initial position is p ₀ , and the actual position p _xa when p ₀ moves in the x direction is expressed as follows:

Among them, the expression of the initial position p ₀ is as follows:

p ₀ =[x _p0 ,y _p0 ,z _p0 ,1] ^T (2)

x _p0 , y _p0 , z _p0 are the coordinate values of p ₀ in the X, Y, and Z directions;

is the transformation matrix translated along the X direction expressed by the screw;

is the transformation matrix expressed by the screw along the Y direction translation of the straightness error;

is the transformation matrix that rotates along the X direction expressed by the screw;

is the transformation matrix that rotates along the Z direction expressed by the screw;

Assumptions:

p _xa =[x _xpa ,y _xpa ,z _xpa ,1] ^T (3)

Among them, x _xpa , y _xpa , z _xpa are the coordinate values of p _xa in the X, Y, and Z directions,

Then the comprehensive straightness error δ _ysx :

δ _ysx = y _xpa -y _p0 (4)

in,

y _xpa ＝y _p0 +δ _yx -z _p0 sinε _xx +x _p0 sinε _zx (6)

In this way, according to (4) (6):

δ _ysx = δ _yx -z _p0 sinε _xx +x _p0 sinε _zx (7)

Thus there are:

δ _yx ＝ δ _ysx + z _p0 sinε _xx -x _p0 sinε _zx (8)

Similarly, the laser displacement sensor measures point Q, and its starting position q0 is _:

q ₀ ＝[0,y _q0 ,0,1] ^T (9)

Among them, y _q0 is the coordinate value of q ₀ in the Y direction;

When the point Q moves in the X direction, the actual position q _xa is:

q _xa =[x _xqa ,y _xqa ,z _xqa ,1] ^T (10)

Among them, x _xqa , y _xqa , z _xqa are the coordinate values of q _xa in the three directions of XYZ, and there are

And, the straightness deviation δ _ylx of the laser displacement sensor is:

δ _ylx = y _xqa -y _q0 (12)

Similar to (7), it can be obtained that

δ _ylx = δ _yx -z _q0 sinε _xx +x _q0 sinε _zx (13)

And, the straightness error δ _ygx of the base surface of the guide rail is:

δ _ygx = y _lx - y _lx0 - δ _ylx (14)

Substitute (13) into (14) to get

δ _ygx = y _lx -y _lx0 -δ _yx +z _q0 sinε _xx -x _q0 sinε _zx (15)

Continue substituting (8) into (15) to get

δ _ygx ＝y _lx -y _lx0 -δ _ysx +(x _p0 -x _q0 )sinε _zx +(z _q0 -z _p0 )sinε _xx (17)

Among them, δ _ysx , ε _zx , ε _xx are measured by laser interferometer, y _lx , y _lx0 are read by laser displacement sensor reading, x _p0 , x _q0 , z _q0 , z _p0 are all known parameters, namely The precise value of the straightness error δ _ygx of the base surface of the guide rail can be calculated according to formula (17).

Further, in step (1), the reflector of the laser interferometer is fixed on the gauge block through the magnetic suction seat and the connecting rod, and the angle of the reflector can be fine-tuned; the laser displacement sensor and its installation fixture are fixed together by screws, and then the installation fixture Fastened to the gauge block by strong magnets.

Further, the laser head of the laser interferometer is fixed on the micro-motion platform, and then installed on the side of the guide rail, and the displacement of the laser head in the three directions of X, Y, and Z is adjusted through the micro-motion platform to adjust the optical path of the laser interferometer collimation.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects: The method for identifying the straightness error of the base surface of the precision guide rail of the machine tool proposed by the present invention uses a laser interferometer to measure the standard gauge block The straightness error and angle error during sliding and the indication error measured by the laser displacement sensor, and the movement of each part are expressed based on the screw theory, and the straightness error value of the base surface of the guide rail is finally calculated by the data processing method of error decoupling , in order to achieve the purpose of measuring the straightness error of the base surface of the precision guide rail, which has the advantages of accuracy and certain feasibility, and can be used in the research of the production quality inspection and analysis of CNC machine tools or the analysis of machine tool accuracy.

Description of drawings

Fig. 1 is a specific implementation flow chart of the decoupling identification method of the straightness error of the guide rail base surface of a precision machine tool based on laser measurement according to the present invention;

Figure 2 is a schematic diagram of the installation of the measurement platform based on laser measurement of the straightness error of the base surface of the guide rail of the precision machine tool;

Figure 3a is the Y-direction straightness error result curve measured by the laser interferometer;

Figure 3b is the result curve of the Z-direction angle error measured by the laser interferometer;

Figure 3c is the X-direction angle error result curve measured by the laser interferometer;

Fig. 3d is the display result curve of the laser displacement sensor;

Figure 4a is the result curve of the straightness error in the Y direction of the identified guide rail base surface;

Fig. 4b is the result curve after zeroing the end point of the straightness error of the Y direction of the identified guide rail base surface.

Reference signs:

1-standard gauge block, 2-interferometer mirror, 3-connecting rod, 4-magnetic base, 5-laser displacement sensor, 6-installation fixture, 7-strong magnet.

detailed description

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not constitute a conflict with each other.

What is described below is a specific embodiment of the present invention, a laser measurement-based decoupling identification method for the straightness error of the guide rail base surface of a precision machine tool. The method specifically includes:

(1) Construction of the measurement platform

The measurement platform is mainly composed of two parts, the basic component and the measurement component. As shown in Figure 2, the basic component includes a guide rail and a standard gauge block 1. The standard gauge block 1 is placed flat on the base surface of the guide rail to be measured, and the Reflect the vertical straightness error of the base surface of the guide rail; the measurement component includes a laser interferometer and a laser displacement sensor 5 components, the mirror 2 of the laser interferometer is fixed on the gauge block through the magnetic base 4 and the connecting rod 3, and is measured by the laser interferometer Straightness and angle errors when the gauge block moves on the guide rail surface. Install the laser head of the laser interferometer on the side of the guide rail to be measured through the micro-movement platform, the laser interferometer mirror 2 is installed on the top of the standard gauge block 1 and is set facing the laser head, and the laser displacement sensor 5 is installed on the standard gauge block 1 And it is located on the front side of the standard gauge block 1; the laser displacement sensor 5 and its installation fixture 6 are fixed together by screws, and then the fixture 6 is adsorbed on the strong magnet 7, and the magnet 7 is then magnetically fixed on the gauge block. In this way, when the equivalent block moves on the base surface of the guide rail, the corresponding error term of its movement can be reflected by the laser interferometer and the laser displacement sensor 5 at the same time, and finally the straightness error of the precision guide rail can be identified.

Installation instructions for other components: Put the laser head of the laser interferometer on the micro-motion platform, and then install it on the side of the guide rail. The displacement in three vertical directions can be adjusted through the micro-motion platform to adjust the optical path alignment of the laser interferometer. And the temperature and humidity sensor 5 is installed to compensate the influence of ambient temperature, humidity and material temperature on the measurement result. The laser displacement sensor 5 can adjust the installation position and angle, so that it is within the most suitable measurement range.

(2) Acquisition of measurement data of the base surface of the guide rail:

After the measurement platform is built, turn on the power to preheat the laser interferometer and laser displacement sensor 5, adjust the measurement optical path of the laser interferometer, confirm that the display of the laser displacement sensor 5 is normal, and use the length of the standard gauge block 1 as the step size, and Set the measurement parameters of the laser interferometer according to the stroke. The laser interferometer returns to zero at the starting point and records the value of the displacement sensor 5 at the starting point. Each time the step length of the gauge block is moved, and each step is marked on the guide rail accordingly. The position the secondary gauge moves to. Start to move the gauge block, and trigger the laser interferometer controller after moving to the designated position. The controller will automatically collect data and record the indication of the displacement sensor 5 at this time, and repeat it many times until the end of the stroke measurement is completed. When moving the gauge block, pay attention to sticking to the side of the guide rail and not touching the magnetic suction seat and the strong magnet 7. In this way, the required data is collected.

It should be noted that the laser interferometer used in this measurement platform can measure the geometric errors of 6 moving pairs at a time, so the required data can be collected by moving a whole journey. If a traditional laser interferometer such as Renishaw XL80 is used, it is necessary to install different mirror groups multiple times and repeat the measurement many times to obtain all the required error terms. Since this type of interferometer is not used in the present invention, no further description is given.

(3) Data processing:

The base surface of the guide rail is generally adjusted by scraping and flattening, which has high precision. However, the commonly used measurement data incorporates the influence of various error factors. Ignoring the influence of these factors will lead to the loss of measurement accuracy. The errors introduced in this patent according to the measurement method of this measuring platform mainly include the straightness deviation δ _yx when the standard gauge block 1 moves, and the pitch angle deviation ε _zx and roll angle deviation ε _xx in the angular deviation. These three errors will introduce relatively large Large measurement errors. Therefore, by adding laser interferometer measurement, the angular deviation ε _zx , ε _xx and the comprehensive straightness error δ _ysx can be obtained. According to the properties of rigid body space motion, the motion of any rigid body in space can be converted into the movement of a point on the rigid body and the movement around this point. turn. Accordingly, according to the screw theory in robot kinematics, the movement of the gauge block and the displacement sensor 5 is accurately expressed, and the starting point of measurement is taken as the zero point of the global coordinate system. The direction of the coordinate axes is defined as shown in Figure 2. The displacement of the gauge block motion for x. First express the comprehensive straightness error δ _ysx of the laser interferometer mirror 2 fixed on the gauge block, and derive the straightness deviation δ _yx around a point on the gauge block, and secondly, according to the derived straightness deviation δ _yx and the measured angle The deviations ε _zx and ε _xx establish the motion model of the sensor 5, and then obtain the straightness deviation δ _ylx of the sensor 5, and finally measure the reading result y _lx of the sensor 5, the reading y _lx0 of the starting point of the sensor 5 and the straightness of the sensor 5 The deviation δ _ylx is calculated to obtain the straightness error δ _ygx of the base surface of the guide rail at the position measured by the sensor 5 .

The specific data processing process is as follows:

As shown in the figure, measure the straightness in the y direction, and the straightness obtained is also the straightness in the y direction, and the direction of the coordinate system is shown in the figure.

The measurement point on the mirror of the laser interferometer is P, and its initial position is p ₀ ,

in,

The initial position p ₀ is:

p ₀ =[x _p0 ,y _p0 ,z _p0 ,1] ^T (2)

Among them, x _p0 , y _p0 , z _p0 are the coordinate values of p ₀ in the three directions of X, Y, and Z;

p _xa is the actual position when the initial position p ₀ moves in the X direction;

is the transformation matrix translated along the X direction expressed by the screw;

is the transformation matrix expressed by the screw along the Y direction translation of the straightness error;

is the transformation matrix that rotates along the X direction expressed by the screw;

is the transformation matrix expressed by the screw along the Z direction.

suppose

p _xa =[x _xpa ,y _xpa ,z _xpa ,1] ^T (3)

Among them, x _xpa , y _xpa , z _xpa are the coordinate values of p _xa in the X, Y, and Z directions,

Then the comprehensive straightness error δ _ysx is:

δ _ysx = y _xpa -y _p0 (4)

in,

y _xpa ＝y _p0 cosε _xx cosε _zx +δ _yx cosε _xx cosε _zx -z _p0 cosε _zx sinε _xx +x _p0 sinε _zx (5)

The minimal error term in the above test can be simplified, that is,

y _xpa ＝y _p0 +δ _yx -z _p0 sinε _xx +x _p0 sinε _zx (6)

In this way, according to (4) (6) can be calculated

δ _ysx = δ _yx -z _p0 sinε _xx +x _p0 sinε _zx (7)

thus have

δ _yx ＝ δ _ysx + z _p0 sinε _xx -x _p0 sinε _zx (8)

Similarly, the point on the measuring head of the displacement sensor is Q, and its starting position q ₀ is

q ₀ ＝[0,y _q0 ,0,1] ^T (9)

Among them, y _q0 is the coordinate value of q ₀ in the Y direction;

The actual position of point Q when moving in the x direction is:

q _xa =[x _xqa ,y _xqa ,z _xqa ,1] ^T (10)

Among them, x _xqa , y _xqa , z _xqa are the coordinate values of q _xa in the three directions of XYZ, and there are

and have

δ _ylx = y _xqa -y _q0 (12)

Similar to (7), it can be obtained that

δ _ylx = δ _yx -z _q0 sinε _xx +x _q0 sinε _zx (13)

Straightness error of guide rail base surface

δ _ygx = y _lx - y _lx0 - δ _ylx (14)

Substitute (13) into (14) to get

δ _ygx = y _lx -y _lx0 -δ _yx +z _q0 sinε _xx -x _q0 sinε _zx (15)

Continue substituting (8) into (15) to get

δ _ygx ＝y _lx -y _lx0 -δ _ysx -z _p0 sinε _xx +x _p0 sinε _zx +z _q0 sinε _xx -x _q0 sinε _zx (16)

Simplified to

δ _ygx ＝y _lx -y _lx0 -δ _ysx +(x _p0 -x _q0 )sinε _zx +(z _q0 -z _p0 )sinε _xx (17)

Accordingly, the corresponding straightness error δ _ysx , pitch angle deviation ε _zx , roll angle deviation ε _xx , and displacement sensor readings y _lx , y _lx0 , plus fixed known parameters x _p0 , x _q0 are obtained through interferometer measurement , z _q0 , z _p0 , that is, the exact value of the straightness error δ _ygx of the base surface of the machine tool guide rail can be calculated.

The above steps are shown in Figure 1.

As an application example, the above method is used for measurement, and the obtained data result curve is shown in Figure 3. The result curve obtained by the above data processing method is shown in Fig. 4 .

According to previous research results, the straightness of the base surface of the guide rail often presents a certain sinusoidal waveform with a certain wavelength. From the result curve in Fig. 4, it is consistent with the above-mentioned research results, indicating that the method of the present invention is feasible, but the present invention is not limited to this example.

The method of the invention can identify the straightness error of the base surface of the guide rail of the precision machine tool, and is suitable for the research on the detection and analysis of the production quality of the numerical control machine tool or the precision analysis of the machine tool.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (4)

1. A decoupling identification method for guide rail base plane straightness errors is characterized by comprising the following steps:

(1) building a measuring platform:

installing a laser head of a laser interferometer on one side of a guide rail to be measured, installing a reflecting mirror of the laser interferometer on the top of the standard gauge block and arranging the reflecting mirror towards the laser head, and installing a laser displacement sensor on the standard gauge block and positioned on the front side of the standard gauge block; horizontally placing the standard gauge block on a guide rail base surface to be measured;

(2) measuring and obtaining initial parameters:

the standard gauge block is made to abut against the surface to be measured of the guide rail, the standard gauge block is moved, and when the standard gauge block moves to a position, the measurement result of the laser interferometer and the measurement result y of the laser displacement sensor at the position are recorded_lx(ii) a The measurement result of the laser interferometer comprises a pitch angle deviation in angle deviations when the standard gauge block moves_zxDeviation of roll angle_xxAnd combined straightness error_ysx(ii) a Initial point index y of laser displacement sensor_lx0；

(3) And (3) error data processing:

with a starting position P of a measuring point P on the mirror₀As a zero point of a global coordinate system, the advancing direction of the standard gauge block is an X axis, the vertical direction is an upward Y axis, and a Z axis is determined by a right-hand rule;

according to the comprehensive straightness error of the reflecting mirror measured by the laser interferometer_ysxDeriving the straightness deviation of a certain point on the standard gauge block_yx(ii) a Derived from_yxAnd measured in step (2)_zx、_xxEstablishing a motion model of the laser displacement sensor to further obtain the straightness deviation of the laser displacement sensor_ylx；

According to the measurement result y of the laser displacement sensor_lxInitial point indication y of laser displacement sensor_lx0Deviation from straightness of laser displacement sensor_ylxAnd calculating to obtain the straightness error of the base surface of the guide rail_ygx。

2. The decoupling identification method for the straightness error of the guide rail base surface according to claim 1, wherein the specific data processing process in the step (3) is as follows:

the measuring point on the reflecting mirror of the laser interferometer is P, and the initial position is P₀，p₀Actual position p when moving in the x-direction_xaThe expression is as follows:

$p_{xa}=e^{{\widehat{\mathrm{\ξ}}}_{{\mathrm{\ϵ}}_{zx}}\·{\mathrm{\ϵ}}_{zx}}\·e^{{\widehat{\mathrm{\ξ}}}_{{\mathrm{\ϵ}}_{xx}}\·{\mathrm{\ϵ}}_{xx}}\·e^{{\widehat{\mathrm{\ξ}}}_{{\mathrm{\δ}}_{yx}}\·{\mathrm{\δ}}_{yx}}\·e^{{\widehat{\mathrm{\ξ}}}_X\·x}\·p_0---\left(1\right)$

wherein the initial position p₀The expression is as follows:

p₀＝[x_p0,y_p0,z_p0,1]^T(2)

x_p0,y_p0,z_p0is p₀Coordinate values in X, Y, Z three directions;

a transformation matrix translated in the X direction expressed as a quantum;

a transformation matrix for translation along the straightness error Y direction expressed in terms of a vector;

a transformation matrix rotated in the X direction expressed as a rotation;

a transformation matrix for rotation in the Z direction expressed in terms of a rotation;

suppose that:

p_xa＝[x_xpa,y_xpa,z_xpa,1]^T(3)

wherein x is_xpa,y_xpa,z_xpaIs p_xaThe coordinate values in the three directions of X, Y, Z,

then the resultant straightness error_ysx：

_ysx＝y_xpa-y_p0(4)

Wherein,

y_xpa＝y_p0+_yx-z_p0sin_xx+x_p0sin_zx(6)

thus, according to (4) (6), there are obtained:

_ysx＝_yx-z_p0sin_xx+x_p0sin_zx(7)

thus, there are:

_yx＝_ysx+z_p0sin_xx-x_p0sin_zx(8)

similarly, the laser displacement sensor measures the point Q, its starting position Q₀Comprises the following steps:

q₀＝[0,y_q0,0,1]^T(9)

wherein, y_q0Is q₀Coordinate values in the Y direction;

actual position Q when point Q moves in the X direction_xaComprises the following steps:

q_xa＝[x_xqa,y_xqa,z_xqa,1]^T(10)

wherein x_xqa,y_xqa,z_xqaIs q_xaAt X, Y, Z, there are coordinate values

$q_{xa}=e^{{\widehat{\mathrm{\ξ}}}_{{\mathrm{\ϵ}}_{zx}}\·{\mathrm{\ϵ}}_{zx}}\·e^{{\widehat{\mathrm{\ξ}}}_{{\mathrm{\ϵ}}_{xx}}\·{\mathrm{\ϵ}}_{xx}}\·e^{{\widehat{\mathrm{\ξ}}}_{{\mathrm{\δ}}_{yx}}\·{\mathrm{\δ}}_{yx}}\·e^{{\widehat{\mathrm{\ξ}}}_X\·x}\·q_0---\left(11\right)$

And, the straightness deviation of the laser displacement sensor_ylxComprises the following steps:

_ylx＝y_xqa-y_q0(12)

the same principle as that of (7) can be obtained,

_ylx＝_yx-z_q0sin_xx+x_q0sin_zx(13)

and, straightness error of the guide rail base surface_ygxComprises the following steps:

_ygx＝y_lx-y_lx0-_ylx(14)

substituting (13) into (14) to obtain

_ygx＝y_lx-y_lx0-_yx+z_q0sin_xx-x_q0sin_zx(15)

Continuing to substitute (8) into (15) to obtain

_ygx＝y_lx-y_lx0-_ysx+(x_p0-x_q0)sin_zx+(z_q0-z_p0)sin_xx(17)

Wherein,_ysx、_zx、_xxmeasured by a laser interferometer to obtain y_lx、y_lx0Obtained by reading the readings of a laser displacement sensor, x_p0、x_q0、z_q0、z_p0All the parameters are known, namely the straightness error of the guide rail base surface can be obtained by calculation according to the formula (17)_ygxThe exact numerical value of (c).

3. The decoupling identification method for the straightness error of the base surface of the guide rail as claimed in claim 1 or 2, wherein in the step (1), the reflecting mirror of the laser interferometer is fixed on the gauge block through a magnetic suction seat and a connecting rod, and the angle of the reflecting mirror can be finely adjusted; the laser displacement sensor and the mounting clamp thereof are fixed together through screws, and then the mounting clamp is fixed on the gauge block through a strong magnet.

4. The decoupling identification method for the straightness error of the guide rail base surface according to claim 1 or 2, wherein: a laser head of the laser interferometer is fixed on the micro-motion platform and then is arranged on one side of the guide rail, and the micro-motion platform is used for adjusting the displacement of the laser head in X, Y, Z three directions so as to adjust the light path collimation of the laser interferometer.