CN102636137B - REVO (Resident Encrypted Variable Output) measuring head position posture calibrating method in joint arm type coordinate measuring machine - Google Patents

Abstract

The invention belongs to the field of testing technology and instruments. In order to provide a calibration method for an articulated arm type coordinate measuring machine that can improve measurement accuracy, the technical solution adopted in the present invention is that the position and attitude calibration method of the REVO probe in an articulated arm type coordinate measuring machine is performed on the measuring machine device: The method includes the following steps: establish a coordinate system, the x-axis is parallel to the x-axis of the REVO probe, the z-axis is parallel to the z-axis of the REVO probe, and the y-axis is perpendicular to the x-axis and the z-axis; calibrate the B-axis of the REVO probe Parallelism with the z-axis motion axis: In order to determine the parallelism error of the A-axis of the Revo probe relative to the x-axis motion axis on the xoy coordinate plane, it is necessary to place another plane vertically on an existing standard plane for measurement . The invention is mainly applied to measurement.

Description

Calibration method of position and attitude of REVO probe in articulated arm coordinate measuring machine

technical field

The invention belongs to the field of testing technology and instruments, and specifically relates to a method for calibrating the position and attitude of a REVO measuring head in an articulated arm type coordinate measuring machine.

Background technique

The development of the national economy and national defense has higher and higher requirements for the precision of products, and the proportion of various parts with complex shapes is increasing. These high-precision and complex parts have long processing time and high processing costs, and the losses caused by unqualified products are large. It is of great significance to use appropriate detection devices during the processing process to timely detect various size, shape, and position parameters of the processed parts for improving processing accuracy, ensuring product quality, and preventing or reducing waste products.

Due to the influence of processing and installation errors and other factors, there are many systematic errors in the coordinate measuring machine, such as the parallelism of each motion axis, the length of the connecting plate, the zero point, etc. Their actual size is very different from the theoretical value of the design, and must be calibrated The method is used to obtain the specific value of each system error, and then the measurement model is corrected and compensated to make the measuring machine have a higher accuracy.

The articulated arm coordinate measuring machine shown in Figure 1 is an instrument dedicated to online and in-situ measurement of the overall blisk of the engine, large gears, and large boxes. The measuring machine has a total of 5 axes of motion, that is, horizontal motion in the x direction , the rotational movement of the articulated arm, the vertical movement in the z direction, and the rotational movement of the rotating body of the REVO probe around its A-axis and B-axis, the object to be measured is measured through the movement of these five degrees of freedom. Among them, the rotation axis of the rotating body of the REVO probe in the horizontal plane is the A axis, and the rotation axis in the vertical plane is the B axis, as shown in Figure 2. Due to the existence of processing and installation errors, there are parallelism errors between the A axis and the x-axis, and the B-axis and the z-axis. Therefore, it is necessary to calibrate the two parallelism errors to establish a measurement mathematical model. There is no relevant record in the prior art, so the precision of the measurement result is not high.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a calibration method for an articulated arm coordinate measuring machine that can improve measurement accuracy. To achieve the above purpose, the technical solution adopted by the present invention is that REVO The calibration method of the position and attitude of the probe is carried out on the following devices:

The device is composed of articulated arm, REVO measuring head, z-direction moving parts, x-direction moving parts, error compensation system, data processing and control computer, and electric motor;

The articulated arm is made of carbon fiber with small specific gravity and large elastic modulus; the front end of the articulated arm is equipped with a REVO probe, and the articulated arm is set on a precision shaft system with small radial and axial motion errors and small angular pendulum motion errors. A motor is installed at the end of the precision shaft system, and the motor drives the precision shaft system and the joint arm to rotate, and the rotated angle is measured by the precision angle measuring system on the shaft system.

The z-direction moving parts are composed of a z-direction slide plate and a guide rail seat. The seat of the precision shaft system is fixed on the z-direction slide plate. The two sliders on the z-direction slide plate and the precision guide rail on the z guide rail seat form a linear motion guide rail pair. z The grating ruler and the reading head are respectively installed on the sliding plate and the z-guiding rail seat, and the moving amount of the z-directing sliding plate relative to the z-guiding rail seat is read by the grating ruler and the reading head. Under the control of the computer, the motor passes through its reduction box and wire The bar drives the z-direction slide to move to the desired position;

The x-direction moving part is composed of an x-direction slide plate, and the z-direction guide rail seat is fixed on the x-direction slide plate. Equipped with a grating ruler and a reading head, use the grating ruler and the reading head to read the movement of the x-direction slide relative to the base; under the control of the computer, the third motor drives the x-direction slide to move through its reduction box and lead screw to the desired location;

The method comprises the steps of:

Establish a coordinate system, the x-axis is parallel to the x-axis of the REVO probe, the z-axis is parallel to the z-axis of the REVO probe, and the y-axis is perpendicular to the x-axis and z-axis;

Follow the steps below to calibrate the parallelism between the B-axis of the REVO probe and the z-axis of motion:

First, let the REVO probe rotate around the B axis, and the probe measures a circular arc on a horizontally placed standard plane to obtain the inclination information of the plane relative to the axis of the B axis: take representative 3 points A on the circular arc , B, C, the corresponding coordinates of REVO probe indication are (x _A , y _A , z _A ), (x _B , y _B , z _B ), (x _C , y _C , z _C ), point D is The midpoint of the line segment BC, the coordinates of point D (x _D , y _D , z _D ), if the plane is ideal, there is no error, or its error has been compensated, then the inclination of the plane relative to the B-axis around the x-axis _θ1 can be expressed as:

θ ₁ =(z _B -z _C )/(y _B -y _C ) (1)

The inclination θ ₂ of the plane around the y-axis relative to the B-axis axis can be expressed as:

θ ₂ =(z _A -z _D )/(x _A -x _D )=[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/2] (2 )

Then, move the x-direction slide, and the REVO probe measures a straight line EF on the standard plane, and set the coordinates of E and F as (x _E , y _E , z _E ), (x _F , y _F , z _F ) , then the inclination θ ₃ of the plane relative to the x-axis motion axis can be expressed as:

θ ₃ =(z _E -z _F )/(x _E -x _F ) (3)

Equations (2) and (3) are the inclinations of the plane relative to the B-axis axis and the x-axis motion axis respectively, then the perpendicularity error _ε1 of the B-axis axis relative to the x-axis motion axis can be expressed as:

ε ₁ ＝θ ₃ -θ ₂ ＝(z _E -z _F )/(x _E -x _F )-[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/twenty four)

The perpendicularity error of the z-direction motion axis relative to the x-direction motion axis can be considered ideal, or it has been calibrated in advance, and its perpendicularity error is ε ₂ , so that the axis of the B-axis relative to the z-direction motion can be obtained in the xoz coordinate plane Parallelism error μ ₁ on :

μ ₁ =ε ₁ -ε ₂ =(z _E -z _F )/(x _E -x _F )-[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/2]-ε ₂ (5)

Place a standard plane vertically on the standard plane that has been placed horizontally, and measure the movement in the z direction. According to the change of the indication value of the REVO probe in the y direction when the z direction passes through the unit distance, it can be determined that the plane is relative to the z direction. The inclination θ ₄ to the motion axis, so as to calculate the parallelism error μ ₂ of the B-axis axis relative to the z-axis motion axis on the yoz coordinate plane:

μ ₂ =θ ₄ -θ ₁ =θ ₄ -(z _B -z _C )/(y _B -y _C ) (6)

Calibration of the parallelism between the A axis of the REVO probe and the x-axis motion axis: Let the probe rotate around the A axis, measure an arc line on a standard plane vertically, and take three points A' and B' on the arc line , C', the coordinates are (x _A' , y _A' , z _A' ), (x _B' , y _B' , z _B' ), (x _C' , y _C' , z _C' ), Point D' is the midpoint of the line segment B'C', and the coordinates of point D' are (x _D' , y _D' , z _D' ), then the inclination of the plane relative to the A-axis of the REVO probe around the z-axis is expressed by η ₁ for:

η ₁ =(x _B' -x _C' )/(y _B' -y _C' ) (7)

The inclination η ₂ of the plane relative to the A-axis of the REVO probe around the y-axis is expressed as:

η ₂ =(x _A' -x _D' )/(z _A' -z _D' )=[x _A' -(x _B' +x _C' )/2]/[z _A' -(z _B' +z _C' )/2] (8)

Then, move the z-direction slide plate, a straight line E'F' on the measuring plane of the REVO probe, and the coordinates of two points E' and F' are (x _E' , y _E' , z _E' ), (x _F' , y _F' , z _F' ), then the inclination η ₃ of the plane relative to the z-direction motion axis is expressed as:

η ₃ =(x _E' -x _F' )/(z _E' -z _F' ) (9)

Then the verticality error ε ₃ of the A-axis of the REVO probe relative to the z-direction movement is expressed as:

ε ₃ =η ₃ -η ₂ =(x _E' -x _F' )/(z _E' -z _F' )-[x _A' -(x _B' +x _C' )/2]/[z _{A '} -(z _B' +z _C' )/2] (10)

Thereby, the parallelism error μ ₃ of the A-axis axis relative to the x-direction motion axis on the xoz coordinate plane can be expressed as:

μ ₃ =ε ₃ -ε ₂ =(x _E' -x _F' )/(z _E' -z _F' )-[x _A' -(x _B' +x _C' )/2]/[z _{A '} -(z _B' +z _C' )/2]-ε ₂ (11)

In order to determine the parallelism error of the A-axis of the Revo probe relative to the x-direction motion axis on the xoy coordinate plane, it is necessary to place another plane vertically on the existing standard plane, move the x-direction slide, and measure the REVO probe The deviation of the other plane in the y direction, according to the change of the indication value of the REVO probe when the x direction walks through the unit distance, determine the inclination η ₄ of a standard plane placed vertically relative to the x direction motion axis, so as to calculate the REVO measurement Parallelism error of the A-axis of the head relative to the x-direction movement on the xoy coordinate plane μ ₄

μ ₄ =η ₄ -η ₁ =η ₄ -(x _B' -x _C' )/(y _B' -y _C' ) (12)

The standard plane is a marble plane.

Technical characteristics and effects of the present invention:

The present invention respectively calibrates the parallelism calibration of the B-axis and the z-direction motion axis of the REVO probe, and the parallelism calibration between the A-axis and the x-direction motion axis of the REVO probe. The calibration of the head position and attitude improves the overall measurement accuracy.

Description of drawings

Figure 1 is a schematic diagram of the structure of an articulated arm coordinate measuring machine.

Figure 2 is a schematic diagram of the structure of the REVO probe.

Figure 3 is a schematic diagram of the REVO measuring head rotating around the B-axis to measure the arc on the standard plane.

Fig. 4 is a schematic diagram of circular arc lines placed horizontally on a standard plane. In the figure (x _A , y _A , z _A ), (x _B , y _B , z _B ), (x _C , y _C , z _C ), (x _D , y _D , z _D ) are REVO probe display The values correspond to the coordinates of points A, B, C, and D, respectively.

Figure 5 is a schematic diagram of a straight line on the standard plane measured by the REVO probe when the sliding plate of the measuring machine is moved along the x direction.

Fig. 6 is a schematic diagram of the inclination between the measuring standard plane and the movement in the z direction when the sliding plate of the measuring machine is moved along the z direction.

Figure 7 is a schematic diagram of the REVO measuring head probe rotating around the A-axis to measure the arc on the standard plane.

Fig. 8 is a schematic diagram of arc lines placed vertically on a standard plane. In the figure (x _A' , y _A' , z _A' ), (x _B' , y _B' , z _B' ), (x _C' , y _C' , z _C' ), (x _D' , y _D' , z _D' ) are the coordinates of points A', B', C' and D' respectively corresponding to the indicated value of REVO probe.

Figure 9 is a schematic diagram of the inclination between the standard plane and the x-direction movement of the REVO probe when the sliding plate of the measuring machine is moved along the x-direction.

Detailed ways

The invention provides a method for calibrating the position and attitude of the REVO probe. The calibration includes two aspects: one is the calibration of the parallelism between the B-axis and the z-direction motion axis of the REVO probe, and the other is the calibration of the A-axis and the x-direction of the REVO probe. Calibration of the parallelism of the axes of motion.

For the convenience of illustration, a coordinate system as shown in Fig. 1 is established, the x-axis is parallel to the x-axis, the z-axis is parallel to the z-axis, and the y-axis is perpendicular to the x-axis and z-axis. The parallelism calibration of the B-axis and the z-axis of the REVO probe can be divided into two aspects, one is the parallelism calibration of the B-axis and the z-axis in the xoz coordinate plane, and the other is the calibration of the B-axis and the z-axis Parallelism calibration in the yoz coordinate plane. Similarly, the calibration of the parallelism between the A-axis and the x-axis of the REVO probe also needs to be calibrated on the xoz coordinate plane and the xoy coordinate plane respectively.

The principle for calibrating the parallelism between the B-axis and the z-axis of the REVO probe is as follows:

First, let the REVO probe rotate around the B axis, and the probe measures a circular arc on a horizontally placed standard plane, as shown in Figure 3. Through data processing, the inclination information of the plane relative to the B-axis axis is obtained. For the convenience of explanation, three representative points A, B, and C are taken on the arc line, as shown in Figure 4, and their coordinate values are (x _A , y _A , z _A ), (x _B , y _B , z _B ), (x _C , y _C , z _C ), point D is the midpoint of line segment BC, and the coordinates of point D are (x _D , y _D , z _D ). Here the plane is considered to be ideal, without error, or its error has been compensated. Then the inclination θ ₁ of the plane relative to the B-axis around the x-axis can be expressed as

θ ₁ =(z _B -z _C )/(y _B -y _C ) (1)

The inclination θ ₂ of the plane around the y-axis relative to the B-axis axis can be expressed as:

θ ₂ =(z _A -z _D )/(x _A -x _D )=[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/2] (2 )

Then, move the sliding seat of the measuring machine along the x direction, and the REVO probe measures a straight line EF on the standard plane, as shown in Figure 5. Assuming that the coordinates of points E and F are (x _E , y _E , z _E ), (x _F , y _F , z _F ) respectively, then the inclination θ ₃ of the plane relative to the x-direction motion axis can be expressed as

θ ₃ =(z _E -z _F )/(x _E -x _F ) (3)

Formulas (2) and (3) are the inclinations of the plane relative to the B-axis axis and the x-axis motion axis, so that the B-axis axis and the x-axis motion axis are linked together by introducing a standard plane. Then the verticality error ε ₁ of the B-axis axis relative to the x-axis motion axis can be expressed as:

ε ₁ ＝θ ₃ -θ ₂ ＝(z _E -z _F )/(x _E -x _F )-[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/twenty four)

The perpendicularity error of the z-direction motion axis relative to the x-direction motion axis can be considered ideal, or it has been calibrated in advance, and its perpendicularity error is ε ₂ , so that the axis of the B-axis relative to the z-direction motion can be obtained in the xoz coordinate plane Parallelism error μ ₁ on :

μ ₁ =ε ₁ -ε ₂ =(z _E -z _F )/(x _E -x _F )-[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/2]-ε ₂ (5)

Finally, since the measuring machine has no y-direction movement, it is impossible to use the y-direction movement to directly measure the parallelism error of the B-axis axis relative to the z-direction movement axis on the yoz coordinate plane. In order to determine the parallelism error of the B-axis axis relative to the z-direction motion axis on the yoz coordinate plane, it is necessary to place a standard plane vertically on the existing standard plane to measure the z-direction motion, as shown in Figure 6. Move the slide plate of the coordinate machine in the z direction, and according to the indication value change of the REVO probe in the y direction when the z direction passes through the unit distance, the inclination θ ₄ of the plane relative to the z direction motion axis can be determined, so as to calculate the B axis axis relative to Parallelism error μ ₂ of the z-direction motion axis on the yoz coordinate plane:

μ ₂ =θ ₄ -θ ₁ =θ ₄ -(z _B -z _C )/(y _B -y _C ) (6)

The above is the principle of parallelism calibration between the B-axis and the z-axis of the REVO probe. The calibration principle of the parallelism between the A-axis and the x-axis of the REVO probe is basically the same as above, except that the standard plane is placed vertically. , let the probe rotate around the A axis, and measure an arc on the plane, as shown in Figure 7. Take three points A', B' and C' on the arc line, as shown in Figure 8, the indicated values in the x direction are (x _A' , y _A' , z _A' ), (x _B' , y _B' , z _B' ), (x _C' , y _C' , z _C' ), point D' is the midpoint of line segment B'C', and the coordinates of point D' are (x _D' , y _D' , z _D' ). Then the inclination η ₁ of the plane relative to the A-axis of the REVO probe around the z-axis can be expressed as

η ₁ =(x _B' -x _C' )/(y _B' -y _C' ) (7)

The inclination η ₂ of the plane relative to the A-axis of the REVO probe around the y-axis can be expressed as:

η ₂ =(x _A' -x _D' )/(z _A' -z _D' )=[x _A' -(x _B' +x _C' )/2]/[z _A' -(z _B' +z _C' )/2] (8)

Then, move the carriage of the measuring machine along the z direction, a straight line E'F' on the measuring plane of the REVO probe, and the indicated values of the two points E' and F' are (x _E' , y _E' , z _E' ), (x _F' , y _F' , z _F' ), then the inclination η ₃ of the plane relative to the z-direction motion axis can be expressed as

η ₃ =(x _E' -x _F' )/(z _E' -z _F' ) (9)

Then the verticality error ε ₃ of the A-axis of the REVO probe relative to the z-direction movement can be expressed as

ε ₃ =η ₃ -η ₂ =(x _E' -x _F' )/(z _E' -z _F' )-[x _A' -(x _B' +x _C' )/2]/[z _{A '} -(z _B' +z _C' )/2] (10)

The perpendicularity error of the z-direction motion axis relative to the x-direction motion axis can be considered ideal, or has been calibrated in advance, and its perpendicularity error is ε ₂ , so that the xoz coordinates of the A-axis axis relative to the x-direction motion axis can be obtained The parallelism error μ ₃ on the plane can be expressed as

μ ₃ =ε ₃ -ε ₂ =(x _E' -x _F' )/(z _E' -z _F' )-[x _A' -(x _B' +x _C' )/2]/[z _{A '} -(z _B' +z _C' )/2]-ε ₂ (11)

Finally, since the measuring machine has no y-direction movement, it is impossible to use the y-direction movement to directly measure the parallelism error of the A-axis axis relative to the x-direction movement axis on the xoy coordinate plane. In order to determine the parallelism error of the A-axis of the Revo probe relative to the x-axis on the xoy coordinate plane, another plane needs to be placed vertically on the existing standard plane, as shown in Figure 9. Let the measuring machine carriage move in the x-direction, and the REVO probe measures the deviation of the second plane in the y-direction. According to the indication value change of the REVO probe when the x-direction walks through the unit distance, the inclination η ₄ of the first plane relative to the x-direction motion axis can be determined, and thus the A-axis of the REVO probe relative to the x-direction motion is calculated at xoy Parallelism error on the coordinate plane μ ₄

μ ₄ =η ₄ -η ₁ =η ₄ -(x _B' -x _C' )/(y _B' -y _C' ) (12)

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Calibration is performed on the following devices:

The device is composed of articulated arm, REVO measuring head, z-direction moving parts, x-direction moving parts, error compensation system, data processing and control computer, and electric motor;

The articulated arm is made of carbon fiber with small specific gravity and large elastic modulus; the front end of the articulated arm is equipped with a REVO probe, and the articulated arm is set on a precision shaft system with small radial and axial motion errors and small angular pendulum motion errors. Instead, a motor is installed at the end of the shaft system, and the motor drives the precision shaft system and the joint arm to rotate, and the rotated angle is measured by the precision angle measuring system on the shaft system.

The z-direction moving parts are composed of a z-direction slide plate and a guide rail seat. The seat of the precision shaft system is fixed on the z-direction slide plate. The two sliders on the z-direction slide plate and the precision guide rail on the z guide rail seat form a linear motion guide rail pair. z The grating ruler and the reading head are respectively installed on the sliding plate and the z-guiding rail seat, and the moving amount of the z-directing sliding plate relative to the z-guiding rail seat is read by the grating ruler and the reading head. Under the control of the computer, the motor passes through its reduction box and wire The bar drives the z-direction slide to move to the desired position;

The x-direction moving part is composed of an x-direction slide plate, and the z-direction guide rail seat is fixed on the x-direction slide plate. Equipped with a grating ruler and a reading head, use the grating ruler and the reading head to read the movement of the x-direction slide relative to the base; under the control of the computer, the third motor drives the x-direction slide to move through its reduction box and lead screw to the desired location.

The purpose of the present invention is to propose a method for calibrating the position and attitude of the REVO measuring head, so as to improve the accuracy of subsequent measurement. Specific steps are as follows:

1. Calibrate the parallelism between the B-axis of the REVO probe and the z-axis of motion

1) Place a marble slab horizontally, let the REVO probe rotate around its B axis, and measure an arc on the plane, as shown in Figure 3. Select three points A, B, and C, as shown in Figure 4, and record the coordinates of the three points (x _A , y _B , z _A ), (x _B , y _B , z _B ), (x _C , y _C , z _C ). Then the inclination θ ₁ of the plate relative to the B-axis of the REVO probe around the x-axis can be expressed by formula (1), and the inclination θ ₂ of the plate relative to the B-axis of the REVO probe around the y-axis can be expressed by formula (2).

2) Move the sliding seat of the measuring machine along the x direction, and the REVO probe measures a straight line EF on the flat plate, as shown in Figure 5. Record the coordinate values (x _E , y _E , z _E ) and (x _F , y _F , z _F ) of points E and F. Then the inclination θ ₃ of the plate relative to the x-direction movement can be expressed by (3) formula, and the perpendicularity error ε ₁ of the axis of the REVO probe B axis relative to the x-direction movement axis can be expressed by (4) formula, since the z-direction movement is relatively The perpendicularity error ε ₂ of the x-direction movement has been measured, so the parallelism error μ ₁ of the B-axis axis relative to the z-direction movement axis on the xoz coordinate plane can be expressed by (5) formula.

3) Place a standard square box on the flat plate, and move the sliding seat of the measuring machine along the z direction, as shown in Figure 6. Record the indication value change θ ₄ of the REVO probe in the y direction when the z direction walks through the unit distance, the inclination of the plate relative to the z direction movement is θ ₄ , then the axis of the B axis is at the yoz coordinate relative to the movement axis of the z direction The parallelism error μ ₂ on the plane can be expressed by formula (6).

2. Calibrate the parallelism between the A axis of the REVO probe and the x axis of motion

1) Place a marble slab vertically, let the REVO probe rotate around its A-axis, and measure an arc on the slab, as shown in Figure 7. Select three points A', B', and C', as shown in Figure 8, and record the coordinates of the three points (x _A' , y _A' , z _A' ), (x _B' , y _B' , z _{B '} ), (x _C' , y _C' , z _C' ). Then the inclination η ₁ of the plate relative to the A-axis axis around the z-axis can be represented by formula (7), and the inclination η ₂ of the plate around the y-axis relative to the A-axis axis of the REVO measuring head can be represented by formula (8).

2) Move the carriage of the measuring machine along the z direction, measure the straight line E'F' with the REVO probe, and record the coordinate values of the two points E' and F' (x _E' , y _E' , z _E' ), (x _F' , y _F' , z _F' ), then the inclination η ₃ of the plate relative to the z-direction motion axis can be expressed by formula (9). The perpendicularity error ε ₃ of the A axis of the REVO probe relative to the z-direction motion axis can be expressed by formula (10), so the parallelism μ ₃ of the A-axis axis of the REVO probe relative to the x-direction motion axis on the xoz coordinate plane can be expressed as ( 11) expression.

3) Place a standard square box on the flat plate, as shown in Figure 9. Let the measuring machine carriage move along the x direction, and the REVO probe measures the deviation of the square box in the y direction. Record the indication value change η ₄ of the REVO probe when walking the unit distance in the x direction, then the inclination of the plate relative to the x direction movement is η ₄ , so the A axis of the REVO probe relative to the x direction movement is at the xoy coordinate The parallelism error μ ₄ on the plane can be expressed by (12) formula.

Claims (2)

1. A method for calibrating the position and posture of REVO measuring head in an articulated arm type coordinate measuring machine, characterized in that the calibration is carried out on the following device: The device is composed of articulated arm, REVO measuring head, z-direction moving parts, x-direction moving parts, error compensation system, data processing and control computer, and electric motor; The articulated arm is made of carbon fiber with small specific gravity and large elastic modulus; the front end of the articulated arm is equipped with a REVO probe, and the articulated arm is set on a precision shaft system with small radial and axial motion errors and small angular pendulum motion errors. A motor is installed at the end of the precision shaft system, and the motor drives the precision shaft system and the joint arm to rotate, and the rotated angle is measured by the precision angle measuring system on the shaft system; The z-direction moving parts are composed of a z-direction slide plate and a guide rail seat. The seat of the precision shaft system is fixed on the z-direction slide plate. The two sliders on the z-direction slide plate and the precision guide rail on the z guide rail seat form a linear motion guide rail pair. z The grating ruler and the reading head are respectively installed on the sliding plate and the z-guiding rail seat, and the moving amount of the z-directing sliding plate relative to the z-guiding rail seat is read by the grating ruler and the reading head. Under the control of the computer, the motor passes through its reduction box and wire The bar drives the z-direction slide to move to the desired position; The x-direction moving part is composed of an x-direction slide plate, and the z-direction guide rail seat is fixed on the x-direction slide plate. Equipped with a grating ruler and a reading head, use the grating ruler and the reading head to read the movement of the x-direction slide relative to the base; under the control of the computer, the third motor drives the x-direction slide to move through its reduction box and lead screw to the desired location; The method comprises the steps of: Establish a coordinate system, the x-axis is parallel to the x-axis of the REVO probe, the z-axis is parallel to the z-axis of the REVO probe, and the y-axis is perpendicular to the x-axis and z-axis; Follow the steps below to calibrate the parallelism between the B-axis of the REVO probe and the z-axis of motion: First, let the REVO probe rotate around the B axis, and the probe measures a circular arc on a horizontally placed standard plane to obtain the inclination information of the plane relative to the axis of the B axis: take representative 3 points A on the circular arc , B, C, the corresponding coordinates of REVO probe indication are (x _A , y _A , z _A ), (x _B , y _B , z _B ), (x _C , y _C , z _C ), point D is The midpoint of the line segment BC, the coordinates of point D (x _D , y _D , z _D ), if the plane is ideal, there is no error, or its error has been compensated, then the inclination of the plane relative to the B-axis around the x-axis _θ1 can be expressed as: θ ₁ =(z _B -z _C )/(y _B -y _C ) (1) The inclination θ ₂ of the plane around the y-axis relative to the B-axis axis can be expressed as: θ ₂ =(z _A -z _D )/(x _A -x _D )=[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/2] (2 ) Then, move the x-direction slide, and the REVO probe measures a straight line EF on the standard plane, and set the coordinates of E and F as (x _E , y _E , z _E ), (x _F , y _F , z _F ) , then the inclination θ ₃ of the plane relative to the x-axis motion axis can be expressed as: θ ₃ =(z _E -z _F )/(x _E -x _F ) (3) Equations (2) and (3) are the inclinations of the plane relative to the B-axis axis and the x-axis motion axis respectively, then the perpendicularity error _ε1 of the B-axis axis relative to the x-axis motion axis can be expressed as: ε ₁ ＝θ ₃ -θ ₂ ＝(z _E -z _F )/(x _E -x _F )-[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/twenty four) The perpendicularity error of the z-direction motion axis relative to the x-direction motion axis can be considered ideal, or it has been calibrated in advance, and its perpendicularity error is ε ₂ , so that the axis of the B-axis relative to the z-direction motion can be obtained in the xoz coordinate plane Parallelism error μ ₁ on : μ ₁ =ε ₁ -ε ₂ =(z _E -z _F )/(x _E -x _F )-[z _A -(z _B +z _C )/2]/[x _A -(x _B +x _C )/2]-ε ₂ (5) Place a standard plane vertically on the standard plane that has been placed horizontally, and measure the movement in the z direction. According to the change of the indication value of the REVO probe in the y direction when the z direction passes through the unit distance, it can be determined that the plane is relative to the z direction. The inclination θ ₄ to the motion axis, so as to calculate the parallelism error μ ₂ of the B-axis axis relative to the z-axis motion axis on the yoz coordinate plane: μ ₂ =θ ₄ -θ ₁ =θ ₄ -(z _B -z _C )/(y _B -y _C ) (6) Calibration of the parallelism between the A axis of the REVO probe and the x-axis motion axis: Let the probe rotate around the A axis, measure an arc line on a standard plane vertically, and take representative three points A on the arc line ', B', C', and their coordinates are (x _A' , y _A' , z _A' ), (x _B' , y _B' , z _B' ), (x _C' , y _C' , z _C' ), D' point is the midpoint of line segment B'C', D' point coordinates (x _D' , y _D' , z _D' ), then the inclination of the plane relative to the A-axis axis of the REVO probe around the z-axis The degree η ₁ is expressed as: η ₁ =(x _B' -x _C' )/(y _B' -y _C' ) (7) The inclination η ₂ of the plane relative to the A-axis of the REVO probe around the y-axis is expressed as: η ₂ =(x _A' -x _D' )/(z _A' -z _D' )=[x _A' -(x _B' +x _C' )/2]/[z _A' -(z _B' +z _C' )/2] (8) Then, move the z-direction slide plate, a straight line E'F' on the measuring plane of the REVO probe, and the coordinates of two points E' and F' are (x _B' , y _E' , z _E' ), (x _F' , y _F' , z _F' ), then the inclination η ₃ of the plane relative to the z-direction motion axis is expressed as: η ₃ =(x _E' -x _F' )/(z _E' -z _F' ) (9) Then the verticality error ε ₃ of the A-axis of the REVO probe relative to the z-direction movement is expressed as: ε ₃ =η ₃ -η ₂ =(x _E' -x _F' )/(z _E' -z _F' )-[x _A' -(x _B' +x _C' )/2]/[z _{A '} -(z _B' +z _C' )/2] (10) Thereby, the parallelism error μ ₃ of the A-axis axis relative to the x-direction motion axis on the xoz coordinate plane can be expressed as: μ ₃ =ε ₃ -ε ₂ =(x _E' -x _F' )/(z _E' -z _F' )-[x _A' -(x _B' +x _C' )/2]/[z _{A '} -(z _B' +z _C' )/2]-ε ₂ (11) In order to determine the parallelism error of the A-axis of the Revo probe relative to the x-direction motion axis on the xoy coordinate plane, it is necessary to place another plane vertically on the existing standard plane, move the x-direction slide, and measure the REVO probe The deviation of the other plane in the y direction, according to the change of the indication value of the REVO probe when the x direction walks through the unit distance, determine the inclination η ₄ of a standard plane placed vertically relative to the x direction motion axis, so as to calculate the REVO measurement Parallelism error of the A-axis of the head relative to the x-direction movement on the xoy coordinate plane μ ₄ μ ₄ =η ₄ -η ₁ =η ₄ -(x _B' -x _C' )/(y _B' -y _C' ) (12). 2. The method according to claim 1, characterized in that, said standard plane is a marble plane.

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