Multi-degree-of-freedom detection device and detection method based on physical decoupling

Abstract

The invention discloses a physical decoupling-based multi-degree-of-freedom detection device and a detection method. The device comprises a detection device and a combined target lens device, the detection device comprises a light source device, a first flat spectroscope, a second flat spectroscope, a straightness error sensing device and an angle error sensing device. The combined target lens device comprises a double-sided reflection right-angle prism device; the first flat spectroscope is located on a laser beam path emitted by the light source device; the double-sided reflection rectangular prism device is located on a turning laser beam path of the first flat spectroscope; the second flat spectroscope is positioned on a reflected light beam path of the double-sided reflection right-angle prism device; the straightness error sensing device and the angle error sensing device are located on paths of turning light beams of the second flat spectroscope respectively, the problems of crosstalk errors and range limitation caused by mutual angle coupling are ingeniously avoided, and therefore the measuring precision and the measuring range of the device are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of precision measurement technology, and in particular to a multi-degree-of-freedom detection device and a detection method based on physical decoupling. Background Art

[0002] With the development of precision machining and intelligent manufacturing industries, the requirements for equipment processing and assembly in the field of precision measurement technology and high-end precision equipment manufacturing are constantly increasing. Due to the non-ideal state of CNC machine tools, coordinate measuring machines and other equipment during the design, processing and structural assembly process, geometric errors will occur in the equipment during use, limiting its processing and measurement accuracy. Therefore, geometric error detection and compensation of these devices is an important measure to ensure their accuracy.

[0003] The motion axis will be affected by six degrees of freedom errors during the motion process: positioning error along the motion direction, two-dimensional straightness error perpendicular to the motion axis direction: horizontal and vertical directions, and three angular errors: pitch angle, yaw angle and roll angle. These errors will affect the accuracy and stability of the motion axis. Traditional measurement methods include laser interferometry to measure positioning errors, micrometer to measure straightness errors, and autocollimation to measure angle errors. However, these methods can usually only measure a single element, and multi-degree-of-freedom measurement requires a combination of multiple devices, which is inefficient. In the context of pursuing high precision and high reliability, how to achieve simultaneous measurement of multiple degrees of freedom has become a key concern of the domestic and foreign inspection industry.

[0004] The angle measurement in the existing multi-degree-of-freedom measurement system is mainly based on the principle of autocollimation. How to improve the angle measurement accuracy and measurement range is one of the technical difficulties of the system. However, the existing system has the following problems in the angle measurement process:

[0005] 1. In the process of angle error measurement, due to the placement relationship between the equipment and the movement and deflection of the measured object, the angle information will be coupled with each other, affecting the measurement accuracy. Although error calibration and compensation can be performed through experimental methods, this offline compensation often has limitations in actual measurement;

[0006] 2. During the synchronous measurement process, due to the influence of the sensor's own characteristics, the measurement ranges of different degrees of freedom will be mutually restricted. When the measurement value of the degree of freedom in one direction is too large, the measurement in the other direction will be affected and will not work properly. For example, when performing two-dimensional measurement, because two-dimensional information can be sensed at the same time, if the light spot exceeds the measurement range in the Y-axis direction, the X-axis direction cannot be measured, and the measurement ranges will be mutually restricted.

[0007] In the prior art, a utility model patent with a patent publication number of CN215264115U discloses a reflective optical circulator, in which when a first light beam is incident on a polarization beam splitter prism 2, it is decomposed into two linear polarized lights with polarization directions perpendicular to each other, namely, P polarized light and S polarized light. However, the polarization beam splitter prism in the prior art can only achieve beam splitting, but cannot achieve angle decoupling. Summary of the invention

[0008] The technical problem to be solved by the present invention is to solve the limitation problem of off-line compensation angle error measurement.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] A multi-degree-of-freedom detection device based on physical decoupling includes: a detection device 100 and a combined target mirror device 200;

[0011] The detection device 100 includes a light source device 110, a first flat beam splitter 120, a second flat beam splitter 130, a straightness error sensing device 140, and an angle error sensing device 150; the combined target mirror device 200 includes a double-sided reflective right-angle prism device 210;

[0012] The first flat beam splitter 120 is located on the path of the laser beam emitted by the light source device 110, and the double-sided reflecting right-angle prism device 210 is located on the path of the laser beam emitted by the light source device 110 from the first flat beam splitter 120;

[0013] The second flat beam splitter 130 is located on the path of the light beam reflected by the double-sided reflecting right-angle prism device 210; wherein the double-sided reflecting right-angle prism device 210 reflects two beams of light, one beam of light carries vertical straightness information and yaw angle information, and the other beam of light carries horizontal straightness information and pitch angle information;

[0014] The straightness error sensing device 140 and the angle error sensing device 150 are respectively located on the path of the deflected light beam of the second flat beam splitter 130 , and receive the two light beams reflected by the double-sided reflection right-angle prism device 210 for detection.

[0015] Advantages: Compared with the traditional single plane mirror, the integrated target mirror device 200 can make the measuring beam carry the straightness displacement information and realize the physical decoupling of the angle information, thereby completing the high-precision measurement of four degrees of freedom. The multi-degree-of-freedom detection device has the advantages of simple optical path, high system integration, and easy adjustment. It can perform online measurement, and in the measurement process, it cleverly avoids the crosstalk error and range limitation caused by the mutual coupling of angles, thereby significantly improving the measurement accuracy and measurement range of the device.

[0016] Through the cooperation of the detection device and the combined target mirror device, the angles are decoupled and separated by physical means, and four degrees of freedom measurement including two straightness degrees are achieved at the same time.

[0017] In one embodiment of the present invention, the double-sided reflection right-angle prism device 210 includes a first polarization beam splitter prism 211, a first double-sided reflection right-angle prism 212 and a second double-sided reflection right-angle prism 213; the first double-sided reflection right-angle prism 212 and the second double-sided reflection right-angle prism 213 are arranged at 90°, and the inclined surfaces of the first double-sided reflection right-angle prism 212 and the second double-sided reflection right-angle prism 213 are glued and fixed to the first polarization beam splitter prism 211.

[0018] In one embodiment of the present invention, two right-angle surfaces of the first double-sided reflective right-angle prism 212 are coated with a reflective film, and two right-angle surfaces of the second double-sided reflective right-angle prism 213 are coated with a reflective film.

[0019] In one embodiment of the present invention, the straightness error sensing device 140 and the angle error sensing device 150 are orthogonally arranged in space.

[0020] In one embodiment of the present invention, the straightness error sensing device 140 includes a second polarization beam splitter prism 141, a first planar array position sensitive detector 142 and a second planar array position sensitive detector 143; the second polarization beam splitter prism 141 splits the light beam deflected by the second flat beam splitter 130, the first planar array position sensitive detector 142 and the second planar array position sensitive detector 143 are located on the splitting path of the second polarization beam splitter prism 141, and the first planar array position sensitive detector 142 and the second planar array position sensitive detector 143 are orthogonally arranged; and the first planar array position sensitive detector 142 senses vertical straightness information, and the second planar array position sensitive detector 143 senses horizontal straightness information.

[0021] In one embodiment of the present invention, the angle error sensing device 150 includes a third polarization beam splitter prism 151, a first linear array position sensitive detector 152 and a second linear array position sensitive detector 153; the third polarization beam splitter prism 151 splits the light beam deflected by the second flat beam splitter 130, the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153 are located on the splitting path of the third polarization beam splitter prism 151, and the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153 are orthogonally arranged; and the first linear array position sensitive detector 152 senses pitch angle information, and the second linear array position sensitive detector 153 senses yaw angle information.

[0022] In one embodiment of the present invention, the detection device 100 includes a focusing lens 160 ; the focusing lens 160 is located on the optical path between the second flat beam splitter 130 and the angle error sensing device 150 , and focuses the reflected light passing through the second flat beam splitter 130 into the angle error sensing device 150 .

[0023] The present invention also provides a detection method based on a physically decoupled multi-degree-of-freedom detection device, comprising:

[0024] The combined target mirror device 200 is installed on the object to be measured, and the detection device 100 is installed at the front end of the object to be measured. The placement angle and height of the combined target mirror device 200 are adjusted so that the incident surface and the exit surface of the detection device 100 are on the same horizontal plane and parallel to each other, and the rough adjustment is completed;

[0025] Turn on the light source device 110 to emit a laser beam, adjust the combined target mirror device 200 and the detection device 100 for the second time, so that the light spot is at the geometric center of the detectors in the straightness error sensing device 140 and the angle error sensing device 150, and fix the detection device 100 and the combined target mirror device 200;

[0026] The combined target mirror device 200 moves with the measured object; the straightness error sensing device 140 outputs the displacement values ​​of the laser spot reflected from the double-sided reflection right angle prism device 210, which are respectively in the horizontal direction Δy1 and the vertical direction Δz2. The angle error sensing device 150 outputs the displacement values ​​of the reflected laser spot, which are respectively in the horizontal direction Δy4 and the vertical direction Δz3;

[0027] According to the self-collimation principle and the measurement value of the angle error sensing device 150, the pitch angle error and yaw angle error generated by the combined target mirror device 200 are obtained; and the horizontal straightness error and vertical straightness error generated by the combined target mirror device 200 are obtained by using the measurement value of the pitch angle error, yaw angle error and straightness error sensing device 140.

[0028] In one embodiment of the present invention, the pitch angle error and the yaw angle error are obtained by the following formula:

[0029]

[0030] Wherein, Δβ is the pitch angle error, Δγ is the yaw angle error, f is the focal length of the focusing objective lens, Δz3 is the displacement value of the light spot on the first linear array position sensitive detector along the Z axis, and Δy4 is the displacement value of the light spot on the second linear array position sensitive detector along the Y axis.

[0031] In one embodiment of the present invention, the horizontal straightness error and the vertical straightness error are obtained by the following formula:

[0032]

[0033] Wherein, ΔY is the horizontal straightness error, ΔZ is the vertical straightness error, F is a function of Δy1, Δγ and α, G is a function of Δz2, Δβ and α, α is the roll angle generated by the object under test, Δy1 is the displacement value of the light spot on the second array position sensitive detector along the Y axis, and Δz2 is the displacement value of the light spot on the first array position sensitive detector along the Z axis.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention combines two double-sided reflecting right-angle prisms and a polarizing beam splitter prism as a detection unit of a multi-degree-of-freedom detection device. Taking advantage of the double-sided reflecting right-angle prism's insensitivity to angular changes in a single direction, the angle of the object being measured is separated at the source, and the straightness error detection capability is achieved.

[0036] The present invention uses a polarization beam splitting prism inside a multi-degree-of-freedom detection device to split the beam. The P light is used to sense vertical straightness and yaw angle, and the S light is used to sense horizontal straightness and pitch angle. On the detector plane, the light spot displacement direction is inconsistent due to different straightness and angle, thereby clearly separating the four degrees of freedom information.

[0037] The present invention adopts the principle of self-collimation to measure angles. The laser returned from the combined target mirror device will carry both straightness information and angle information. Since the translation of the laser on the focusing objective lens does not affect the angle measurement relationship of the self-collimation module, combined with the physical decoupling advantage of the combined target mirror device, the light spot only undergoes one-dimensional linear displacement on the angle error sensing device.

[0038] The present invention physically decouples the angle of the measured object, realizes independent measurement of the pitch angle error and the yaw angle error, eliminates the crosstalk between the angle errors, improves the angle measurement accuracy, and avoids the influence of mutual restriction of the measurement range during the simultaneous measurement of the angles.

[0039] The invention is an integrated transceiver device. The combined target mirror device is small in size and light in weight. Compared with the traditional split multi-degree-of-freedom measurement system, it has a wider range of applications, is simpler and more convenient to operate, and is easy to install on various motion rails, reducing the error caused by its own weight to the measurement.

[0040] The present invention can detect the straightness error and the angle error of the moving axis quickly and in real time, has a large measuring range, high precision, good stability, compact structure, and low cost, and is conducive to popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of a multi-degree-of-freedom detection device based on physical decoupling according to an embodiment of the present invention.

[0042] Figure 2Schematic diagram of a double-sided reflecting right-angle prism device according to an embodiment of the present invention.

[0043] Figure 3 and Figure 4 Schematic diagram of the decoupling principle of a double-sided reflecting right-angle prism device according to an embodiment of the present invention.

[0044] Figure 5 The figure is a schematic diagram of the placement positions of four position sensitive detectors and the movement relationship of light spots according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with the accompanying drawings of the specification.

[0046] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0047] See also Figure 1 As shown, the present invention discloses a multi-degree-of-freedom detection device based on physical decoupling, including a detection device 100 and a combined target mirror device 200. The detection device 100 is located at the front end of the object to be detected, and the combined target mirror device 200 is installed on the object to be detected.

[0048] In one embodiment of the present invention, the detection device 100 includes a light source device 110, a first flat beam splitter 120, a second flat beam splitter 130, a straightness error sensing device 140, an angle error sensing device 150, a focusing lens 160, and a two-dimensional displacement adjustment base 170. The light source device 110, the first flat beam splitter 120, the second flat beam splitter 130, the straightness error sensing device 140, the angle error sensing device 150, and the focusing lens 160 are all arranged on the two-dimensional displacement adjustment base 170. The combined target lens device 200 includes a double-sided reflection right-angle prism device 210 and a two-dimensional angle adjustment base 220, and the double-sided reflection right-angle prism device 210 is arranged on the two-dimensional angle adjustment base 220.

[0049] In this embodiment, the first flat beam splitter 120 is located on the path of the laser beam emitted by the light source device 110, and the double-sided reflection right angle prism device 210 is located on the path of the laser beam emitted by the first flat beam splitter 120 and the light source device 110. The second flat beam splitter 130 is located on the path of the reflected beam of the double-sided reflection right angle prism device 210. The double-sided reflection right angle prism device 210 reflects two beams of light, one beam of light carries vertical straightness information and yaw angle information, and the other beam of light carries horizontal straightness information and pitch angle information. The straightness error sensing device 140 and the angle error sensing device 150 are respectively located on the path of the deflected light beam of the second flat beam splitter 130, and receive the two beams of light reflected by the double-sided reflection right angle prism device 210 for detection. The focusing objective lens 160 is located on the optical path between the second flat beam splitter 130 and the angle error sensing device 150, and focuses the reflected light passing through the second flat beam splitter 130 to enter the angle error sensing device 150.

[0050] In this embodiment, the light source device 110 includes a semiconductor laser light source 111, an aperture 112, and a convex lens 113. The aperture 112 and the convex lens 113 are sequentially arranged on the optical path of the laser light emitted by the semiconductor laser light source 111.

[0051] In this embodiment, the straightness error sensing device 140 includes a second polarization beam splitter prism 141, a first area array position sensitive detector 142, and a second area array position sensitive detector 143. The second polarization beam splitter prism 141 splits the light beam deflected by the second flat beam splitter 130, and the first area array position sensitive detector 142 and the second area array position sensitive detector 143 are located on the splitting path of the second polarization beam splitter prism 141, and the first area array position sensitive detector 142 and the second area array position sensitive detector 143 are orthogonally arranged.

[0052] In this embodiment, the angle error sensing device 150 includes a third polarization beam splitter prism 151, a first linear position sensitive detector 152, and a second linear position sensitive detector 153. The third polarization beam splitter prism 151 splits the light beam deflected by the second flat beam splitter 130, and the first linear position sensitive detector 152 and the second linear position sensitive detector 153 are located on the splitting path of the third polarization beam splitter prism 151, and the first linear position sensitive detector 152 and the second linear position sensitive detector 153 are orthogonally arranged. It is ensured that the photosensitive surfaces of the first linear position sensitive detector 152 and the second linear position sensitive detector 153 are both located on the focal plane of the focusing objective lens 160.

[0053] In this embodiment, the laser beam is emitted by a semiconductor laser light source 111 , is collimated by an aperture 112 and a convex lens 113 , is turned by a first flat-plate beam splitter 120 , leaves the detection device 100 , and enters the combined target lens device 200 .

[0054] In this embodiment, the double-sided reflection right angle prism device 210 includes a first polarization beam splitter prism 211, a first double-sided reflection right angle prism 212, and a second double-sided reflection right angle prism 213. The first double-sided reflection right angle prism 212 and the second double-sided reflection right angle prism 213 are arranged at 90 degrees, and the hypotenuses of the first double-sided reflection right angle prism 212 and the second double-sided reflection right angle prism 213 are glued and fixed to the first polarization beam splitter prism 211. Specifically, the fixing glue is glue for optical devices.

[0055] The light beam enters the combined target mirror device 200 and is split into P light and S light by the first polarization beam splitter prism 211. The P light is transmitted into the first double-sided reflection right-angle prism 212, and after two reflections, it leaves the prism with vertical straightness and yaw angle information. The S light is reflected into the second double-sided reflection right-angle prism 213, and after two reflections, it leaves the prism with horizontal straightness and pitch angle information. After carrying the measurement information, the P light and the S light leave the combined target mirror device 200 through the first polarization beam splitter prism 211 and enter the detection device 100 again to receive and process the light information.

[0056] In this embodiment, the two beams of light are split in equal proportion by the second flat beam splitter 130. The reflected light enters the second polarization beam splitter prism 141 for polarization beam splitting. The S light is reflected to the second planar array position sensitive detector 143 to sense the horizontal straightness information. The P light is transmitted to the first planar array position sensitive detector 142 to sense the vertical straightness information. The transmitted light is converged by the focusing objective lens 160 and enters the third polarization beam splitter prism 151. Finally, it is converged on the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153, wherein the first linear array position sensitive detector 152 receives the S light reflected by the third polarization beam splitter prism 151 to sense the pitch angle, and the second linear array position sensitive detector 153 receives the P light transmitted by the third polarization beam splitter prism 151 to sense the yaw angle.

[0057] See also Figures 1 to 4As shown, in one embodiment of the present invention, the double-sided reflection right-angle prism device 210 includes three optical devices: a first polarization beam splitter prism 211, a first double-sided reflection right-angle prism 212, and a second double-sided reflection right-angle prism 213. The laser beam is incident on the double-sided reflection right-angle prism device 210, and after being split by the first polarization beam splitter prism 211, it enters the first double-sided reflection right-angle prism 212 and the second double-sided reflection right-angle prism 213 respectively. The first double-sided reflection right-angle prism 212 and the second double-sided reflection right-angle prism 213 are placed at 90 degrees to each other, so that the P light and the S light respectively sense different geometric error information. When installing the optical devices, the inclined surfaces of the first double-sided reflection right-angle prism 212 and the second double-sided reflection right-angle prism 213 need to be close to the first polarization beam splitter prism 201 to reduce assembly errors. Before the combined target mirror device 200 is fixed to the object to be measured, the positions of the incident light and the outgoing light need to be adjusted so that the laser appears near the geometric center of the combined target mirror device 200, thereby further increasing the measurement range of the device. Compared with the traditional single-bevel coated right-angle prism, the double-sided reflecting right-angle prism is coated with a reflective film on the two right-angle surfaces, so that the incident laser is reflected twice inside to ensure that the incident light is parallel to the outgoing light.

[0058] In this example, see Figure 3 (a) and (b) in the figure indicate that when the first double-sided reflecting right-angle prism 212 is displaced in the vertical direction (generating a vertical straightness error), the outgoing light will undergo a vertical translation change, and when it is displaced in the horizontal direction, the outgoing light remains unchanged. When affected by a change in the pitch angle, the outgoing light will not undergo an angle change, but only a displacement change, and this displacement change can be calculated from the size of the pitch angle, indicating that the vertically placed first double-sided reflecting right-angle prism 212 has the ability to sense vertical straightness and is insensitive to the pitch angle.

[0059] In this example, see Figure 4 (c) and (d) in the figure indicate that when the second double-sided reflecting right-angle prism 213 is displaced in the horizontal direction (generating a horizontal straightness error), the emitted light will undergo a horizontal translation change, and when it is displaced in the vertical direction, the emitted light remains unchanged. When affected by the change in the deflection angle, the emitted light will not undergo an angle change, but only a displacement change, and this displacement change can be calculated from the size of the deflection angle, indicating that the horizontally placed second double-sided reflecting right-angle prism 213 has the ability to sense horizontal straightness and is insensitive to the deflection angle.

[0060] See also Figures 1 to 4As shown, in one embodiment of the present invention, the first polarization beam splitter prism 211 and the two double-sided reflecting right-angle prisms arranged at 90° have the function of physical angle separation and decoupling, which can separate the angle information during the measurement process, reduce the influence of angle coupling on the measurement accuracy and the limitation on the measurement range.

[0061] See also Figure 1 , Figure 5 As shown, in one embodiment of the present invention, the placement directions of all position sensitive detectors are established in Figure 1 The sensing planes of the second area array position sensitive detector 143 and the second linear array position sensitive detector 153 are located on the OYZ plane. The sensing planes of the first area array position sensitive detector 142 and the first linear array position sensitive detector 152 are located on the OXZ plane. The two planes are orthogonal to each other and receive different types of straightness and angle information respectively. It can also be understood that the straightness error sensing device 140 and the angle error sensing device 150 are orthogonally arranged in space. More specifically, the first area array position sensitive detector 142 and the second area array position sensitive detector 143 are orthogonally arranged, and the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153 are orthogonally arranged.

[0062] In this embodiment, during assembly and adjustment, it is necessary to ensure that each laser beam hits the optimal measurement area of ​​each position sensitive detector, so as to ensure that the sensitive detector has a good working range when working. At the same time, since the angle measurement part adopts the self-collimation method to measure the angle, when installing the focusing lens 160, the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153, it is necessary to adjust the front and rear positions of the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153 to ensure that the photosensitive surfaces of the two linear array position sensitive detectors are located on the focal plane of the focusing lens 160, so as to reduce the influence of the defocus error.

[0063] See also Figures 1 to 5 As shown, the present invention also provides a detection method based on a physically decoupled multi-degree-of-freedom detection device, comprising:

[0064] Step a: install the combined target mirror device 200 on the object to be measured, install the detection device 100 at the front end of the object to be measured, adjust the placement angle and height of the combined target mirror device 200 so that its incident surface and the exit surface of the detection device 100 are on the same horizontal plane and parallel to each other, and complete the coarse adjustment.

[0065] Step b, turn on the light source device 110 to emit a laser beam, and adjust the combined target mirror device 200 and the detection device 100 for a second time so that the light spot is at the geometric center of the detectors in the straightness error sensing device 140 and the angle error sensing device 150, and fix the detection device 100 and the combined target mirror device 200.

[0066] In this embodiment, the semiconductor laser light source 111 is turned on, and the two-dimensional displacement adjustment base 170 and the two-dimensional angle adjustment base 220 are adjusted so that the light spots on the first planar array position sensitive detector 142, the second planar array position sensitive detector 143, the first linear array position sensitive detector 152, and the second linear array position sensitive detector 153 are at the center position of the detector, and the detection device 100 and the combined target mirror device 200 are fixed.

[0067] Step c, the combined target mirror device 200 moves with the measured object; the straightness error sensing device 140 outputs the displacement values ​​of the laser spot reflected from the double-sided reflection right angle prism device 210, which are respectively in the horizontal direction Δy1 and the vertical direction Δz2. The angle error sensing device 150 outputs the displacement values ​​of the reflected laser spot, which are respectively in the horizontal direction Δy4 and the vertical direction Δz3.

[0068] In this embodiment, the second planar array position sensitive detector 143 and the first planar array position sensitive detector 142 respectively output displacement values ​​of the light spots reflected from the second double-sided reflection right angle prism 213 and the first double-sided reflection right angle prism 212, which are respectively in the horizontal direction Δy1 and the vertical direction Δz2. The first linear array position sensitive detector 152 and the second linear array position sensitive detector 153 respectively output displacement values ​​of the reflected laser light spots, which are respectively in the horizontal direction Δy4 and the vertical direction Δz3.

[0069] Step d: According to the self-collimation principle and the measurement value of the angle error sensing device 150, the pitch angle error and the yaw angle error generated by the combined target mirror device 200 are obtained; and the horizontal straightness error and the vertical straightness error generated by the combined target mirror device 200 are obtained by using the measurement value of the pitch angle error, the yaw angle error and the straightness error sensing device 140.

[0070] In this embodiment, the pitch and yaw angle errors of the combined target mirror device 200 after physical decoupling are calculated according to the self-collimation principle and the measurement values ​​of the first linear array position sensitive detector 152 and the second linear array position sensitive detector 153. The horizontal straightness error and the vertical straightness error generated by the combined target mirror device 200 are obtained by differential calculation using the measured angle error information and the measurement values ​​of the second planar array position sensitive detector 143 and the first planar array position sensitive detector 142.

[0071] In this embodiment, an O-XYZ coordinate system is established with the device measuring the object, and the optical axis direction of the detection device 100, i.e., the moving direction of the object being measured, is taken as the positive direction of the X axis, the Y axis is perpendicular to the X axis and along the horizontal direction, and the Z axis is along the vertical direction. Among them, the rotation around the X axis generates a roll angle error, the rotation around the Y axis generates a pitch angle error, and the rotation around the Z axis generates a yaw angle error.

[0072] In straightness measurement, due to the influence of angle, the straightness error needs to be solved based on the angle information that has been measured. By performing differential operation based on formula (1), combined with the measurement results of formulas (2) and (3), the horizontal straightness error ΔY and the vertical straightness error ΔZ can be obtained:

[0073]

[0074] Wherein, ΔY is the horizontal straightness error, ΔZ is the vertical straightness error, F is a function of Δy1, Δγ and α, G is a function of Δz2, Δβ and α, α is the roll angle generated by the object under test, Δy1 is the displacement value of the light spot on the second array position sensitive detector along the Y axis, and Δz2 is the displacement value of the light spot on the first array position sensitive detector along the Z axis.

[0075] Due to the characteristics of the combined target mirror device 200, the pitch angle and the yaw angle are decoupled from each other when measuring the angle error. The pitch angle error Δβ and the yaw angle error Δγ can be calculated by formulas (2) and (3):

[0076]

[0077] Wherein, Δβ is the pitch angle error, Δγ is the yaw angle error, f is the focal length of the focusing objective lens, Δz3 is the displacement value of the light spot on the first linear array position sensitive detector along the Z axis, and Δy4 is the displacement value of the light spot on the second linear array position sensitive detector along the Y axis.

[0078] See also Figures 1 to 5 As shown, in one embodiment of the present invention, the measurement principle is: Figure 1 Based on the O-XYZ coordinate system in the figure, it is analyzed that the combined target mirror device 200 has the function of physically decoupling the angles. When the laser is reflected by the combined target mirror device 200, the P light will carry the yaw angle information, the S light will carry the pitch angle information, and the angle of the reflected light beam is not affected by the roll angle.

[0079] Taking the beam propagation direction as the positive direction of the X-axis, the beam expression emitted by the laser light source under ideal conditions is formula (4):

[0080] I d =

[100] T , (4);

[0081] In the formula, I d It is expressed as the beam expression of the incident light, and T represents the transpose.

[0082] When the combined target mirror device 200 undergoes angular deflection of the roll angle α, the pitch angle β and the yaw angle γ, since the values ​​of α, β and γ are small, the quadratic terms in the formula calculation can be ignored, and the reflection matrix expressions (5)-(7) of the first polarization beam splitter prism 211, the first double-sided reflection right-angle prism 212 and the second double-sided reflection right-angle prism 213 are as follows:

[0083]

[0084]

[0085] In the formula, M' PBS It is expressed as the reflection matrix expression when the first polarization beam splitter prism undergoes three-degree-of-freedom angle deflection; M' m202 It is expressed as the reflection matrix expression when the first double-sided reflecting right-angle prism undergoes three-degree-of-freedom angle deflection; M' m203 It is expressed as the reflection matrix expression when the second double-sided reflecting right-angle prism undergoes three-degree-of-freedom angle deflection;

[0086] Since the laser beam will cross the glass plane (prism boundary) twice when entering and exiting the first double-sided reflecting right-angle prism 212 and the second double-sided reflecting right-angle prism 213, this process can be equivalent to a parallel flat plate and the effect of refraction caused by the glass medium can be ignored. dp and I' ds It can be solved according to formula (8) and (9):

[0087] I' dp =M' m202 I d =[-1-2γ0] T , (8);

[0088] I' ds =M' PBS M' m203 M' PBS I d =[-102β] T , (9);

[0089] In the formula, I' dp Expressed as the beam expression of the emitted P light, I' ds Represents the beam expression of the emitted S light.

[0090] It can be seen from formulas (8) and (9) that when the laser passes through the combined target mirror device 200 that undergoes three-degree-of-freedom angle deflection, the reflected P light will only carry the yaw angle information, and the S light will only carry the pitch angle information, and both will not be affected by the roll angle.

[0091] In this embodiment, the angle of the object to be measured can be separated from the source of measurement by combining the target mirror device 200, so that the measured P light and S light carry different angle information respectively, so that the pitch angle error and the yaw angle error can be measured independently in the detection device 100 without interfering with each other, eliminating the influence of crosstalk between different angles and solving the problem of mutual constraints between multiple angle measurement ranges during simultaneous measurement. And while achieving angle decoupling, the device of the present invention can measure the straightness error and realize the simultaneous measurement of the errors of the four degrees of freedom of the moving axis during the movement. The device of the present invention has the characteristics of high measurement accuracy, large range and high stability, and has broad application prospects in precision machining and measuring equipment such as CNC machine tools and coordinate measuring machines.

[0092] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0093] The above-described embodiments merely represent implementation methods of the invention. The protection scope of the present invention is not limited to the above-described embodiments. For those skilled in the art, several modifications and improvements may be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A multi-degree-of-freedom detection device based on physical decoupling, characterized in that: include: A detection device (100) and a combined target mirror device (200); The detection device (100) comprises a light source device (110), a first flat beam splitter (120), a second flat beam splitter (130), a straightness error sensing device (140), and an angle error sensing device (150); the combined target mirror device (200) comprises a double-sided reflection right-angle prism device (210); The first flat beam splitter (120) is located on the path of the laser beam emitted by the light source device (110), and the double-sided reflection right-angle prism device (210) is located on the path of the laser beam emitted by the light source device (110) from the first flat beam splitter (120); The second flat beam splitter (130) is located on the path of the light beam reflected by the double-sided reflecting right-angle prism device (210); wherein the double-sided reflecting right-angle prism device (210) reflects two beams of light, one beam of light carries vertical straightness information and yaw angle information, and the other beam of light carries horizontal straightness information and pitch angle information; The straightness error sensing device (140) and the angle error sensing device (150) are respectively located on the path of the deflected light beam of the second flat beam splitter (130), and receive two beams of light reflected by the double-sided reflection right-angle prism device (210) for detection.

2. The multi-degree-of-freedom detection device based on physical decoupling according to claim 1 is characterized in that: The double-sided reflection right-angle prism device (210) comprises a first polarization beam splitter prism (211), a first double-sided reflection right-angle prism (212) and a second double-sided reflection right-angle prism (213); the first double-sided reflection right-angle prism (212) and the second double-sided reflection right-angle prism (213) are arranged at 90 degrees, and the inclined surfaces of the first double-sided reflection right-angle prism (212) and the second double-sided reflection right-angle prism (213) are glued and fixed to the first polarization beam splitter prism (211).

3. The multi-degree-of-freedom detection device based on physical decoupling according to claim 2 is characterized in that: The two right-angle surfaces of the first double-sided reflecting right-angle prism (212) are coated with a reflecting film, and the two right-angle surfaces of the second double-sided reflecting right-angle prism (213) are coated with a reflecting film.

4. The multi-degree-of-freedom detection device based on physical decoupling according to claim 1 is characterized in that: The straightness error sensing device (140) and the angle error sensing device (150) are arranged orthogonally in space.

5. The multi-degree-of-freedom detection device based on physical decoupling according to claim 1, characterized in that: The straightness error sensing device (140) comprises a second polarization beam splitter prism (141), a first planar array position sensitive detector (142) and a second planar array position sensitive detector (143); the second polarization beam splitter prism (141) splits the light beam deflected by the second flat beam splitter (130); the first planar array position sensitive detector (142) and the second planar array position sensitive detector (143) are located on the splitting path of the second polarization beam splitter prism (141), and the first planar array position sensitive detector (142) and the second planar array position sensitive detector (143) are orthogonally arranged; and the first planar array position sensitive detector (142) senses vertical straightness information, and the second planar array position sensitive detector (143) senses horizontal straightness information.

6. The multi-degree-of-freedom detection device based on physical decoupling according to claim 1 is characterized in that: The angle error sensing device (150) comprises a third polarization beam splitter prism (151), a first linear array position sensitive detector (152) and a second linear array position sensitive detector (153); the third polarization beam splitter prism (151) splits the light beam deflected by the second flat beam splitter (130); the first linear array position sensitive detector (152) and the second linear array position sensitive detector (153) are located on the beam splitting path of the third polarization beam splitter prism (151), and the first linear array position sensitive detector (152) and the second linear array position sensitive detector (153) are orthogonally arranged; and the first linear array position sensitive detector (152) senses pitch angle information, and the second linear array position sensitive detector (153) senses yaw angle information.

7. The multi-degree-of-freedom detection device based on physical decoupling according to claim 1 is characterized in that: The detection device (100) comprises a focusing lens (160); the focusing lens (160) is located on the optical path between the second flat beam splitter (130) and the angle error sensing device (150), and focuses the reflected light passing through the second flat beam splitter (130) to enter the angle error sensing device (150).

8. A detection method based on a physically decoupled multi-degree-of-freedom detection device according to any one of claims 1 to 7, characterized in that: include: The combined target mirror device (200) is mounted on the object to be measured, the detection device (100) is mounted on the front end of the object to be measured, and the placement angle and height of the combined target mirror device (200) are adjusted so that the incident surface and the exit surface of the detection device (100) are on the same horizontal plane and parallel to each other, thereby completing the rough adjustment; Turning on the light source device (110) to emit a laser beam, secondarily adjusting the combined target mirror device (200) and the detection device (100) so that the light spot is located at the geometric center of the detectors in the straightness error sensing device (140) and the angle error sensing device (150), and fixing the detection device (100) and the combined target mirror device (200); The combined target mirror device (200) moves with the measured object; the straightness error sensing device (140) outputs the displacement values ​​of the laser spot reflected from the double-sided reflection right-angle prism device (210), which are respectively in the horizontal direction Δy1 and the vertical direction Δz2. The angle error sensing device (150) outputs the displacement values ​​of the reflected laser spot, which are respectively in the horizontal direction Δy4 and the vertical direction Δz3; According to the self-collimation principle and the measurement value of the angle error sensing device (150), the pitch angle error and the yaw angle error generated by the combined target mirror device (200) are obtained; and using the measurement value of the pitch angle error, the yaw angle error and the straightness error sensing device (140), the horizontal straightness error and the vertical straightness error generated by the combined target mirror device (200) are obtained.

9. The detection method based on the physically decoupled multi-degree-of-freedom detection device according to claim 8, characterized in that: The pitch angle error and yaw angle error are obtained by the following formula: Wherein, Δβ is the pitch angle error, Δγ is the yaw angle error, f is the focal length of the focusing objective lens, Δz3 is the displacement value of the light spot on the first linear array position sensitive detector along the Z axis, and Δy4 is the displacement value of the light spot on the second linear array position sensitive detector along the Y axis.

10. The detection method based on the physically decoupled multi-degree-of-freedom detection device according to claim 9, characterized in that: The horizontal straightness error and vertical straightness error are obtained by the following formula: Wherein, ΔY is the horizontal straightness error, ΔZ is the vertical straightness error, F is a function of Δy1, Δγ and α, G is a function of Δz2, Δβ and α, α is the roll angle generated by the object under test, Δy1 is the displacement value of the light spot on the second array position sensitive detector along the Y axis, and Δz2 is the displacement value of the light spot on the first array position sensitive detector along the Z axis.

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