High-precision tilt angle measuring device based on optical principle and measuring method thereof

Abstract

This application discloses a high-precision tilt angle measuring device and method based on optical principles. The high-precision tilt angle measuring device includes a base, a gravity-sensitive element, a reflective component, a laser emitting unit, a photoelectric detection component, and a signal processing unit. The gravity-sensitive element is rotatably mounted on the base via bearings and can freely swing around a horizontal axis under its own weight. The reflective component is rigidly fixed to the gravity-sensitive element. The laser emitting unit is fixed on the base and is used to emit a laser beam to the reflective component. The photoelectric detection component is fixed on the base and is used to receive the optical signal formed by the laser beam reflected by the reflective component, and can convert the optical signal into an electrical signal. The signal processing unit is used to receive the electrical signal output by the photoelectric detection component, process it through an algorithm corresponding to the characteristics of the optical signal, and then calculate and output the tilt angle value. This application improves the tilt angle detection accuracy.

Description

Technical Field

[0001] This application relates to the field of tilt angle measurement technology, and in particular to a high-precision tilt angle measuring device and its measurement method based on optical principles. Background Technology

[0002] In numerous fields such as precision engineering, geological monitoring, building structural health monitoring, industrial equipment leveling, and precision machinery positioning, the demand for high-precision measurement of object tilt angles is increasingly urgent. The accuracy and reliability of tilt angle measurement directly affect engineering quality assessment, equipment operational stability, and the effectiveness of geological disaster early warning. Therefore, developing tilt angle measurement devices that combine high sensitivity, strong anti-interference capabilities, and compact structure has become one of the core directions of technological development in the industry.

[0003] Traditional tilt measurement often employs technologies such as mechanical levels, resistive sensors, capacitive tilt meters, or MEMS accelerometers. While these devices achieve a certain level of measurement accuracy, they generally suffer from insufficient response sensitivity, significant environmental interference, and limited resolution in detecting minute angle changes.

[0004] To overcome the limitations of traditional solutions, optical principles have been gradually applied to tilt measurement in recent years. While some technological advancements have been made in resolution and anti-interference capabilities, challenges remain, including large structural size, poor stability in complex environments, and limited accuracy of spot positioning analysis algorithms. Taking patent application publication number CN116907442A as an example, its proposed optical tilt sensor utilizes a laser, polarizer, resonant modulation module, condenser, and photoelectric converter working collaboratively to improve signal linearity and anti-interference capabilities, while also achieving miniaturization of some components. However, this solution still has room for improvement in areas such as extremely small angle detection accuracy, system structure optimization, and high-stability real-time processing.

[0005] On the other hand, moiré fringe technology, as a classic optical method for amplifying minute displacements, theoretically has the potential to achieve extremely high angular resolution. However, in the field of tilt measurement, existing moiré fringe technology solutions all follow the inherent "imaging-analysis" approach, that is, using linear or area array image sensors (such as CCD / CMOS) to capture moiré fringe images, and then calculating the fringe movement through complex image processing algorithms (such as fringe centerline extraction, phase analysis, etc.). This method introduces another dilemma: the system structure is complex, the data processing load is large, the cost is high, and it is difficult to achieve real-time, high-speed measurement, which greatly limits its practical application in applications requiring miniaturization, low power consumption, and high reliability.

[0006] In summary, existing technologies present a dilemma: optical solutions based on spot displacement are limited by inherent accuracy bottlenecks and environmental sensitivity; while traditional moiré fringe solutions rely on image sensors and complex processing algorithms, resulting in system redundancy and high costs. Therefore, there is an urgent need for a tilt measurement solution that can combine high resolution, high reliability, compact structure, and simple signal processing. Summary of the Invention

[0007] The purpose of this application is to solve the problem of insufficient response sensitivity of existing tilt measurement equipment, and to propose a high-precision tilt measurement device and its measurement method based on optical principles with high detection accuracy.

[0008] The technical solution adopted in this application to solve its technical problem is: a high-precision tilt angle measuring device based on optical principles, comprising:

[0009] Base;

[0010] A gravity-sensitive element is rotatably mounted on the base via a bearing, and when the base tilts with the object being measured, the gravity-sensitive element can swing freely around a horizontal axis under its own weight; wherein, the horizontal axis coincides with the axis of the bearing.

[0011] A reflective component is rigidly fixed to the gravity-sensitive element. The reflective component has a laser beam reflection function, or the reflective component has a laser beam reflection function and an integrated grating structure on its surface for reflecting the laser beam to form a grating image.

[0012] A laser emitting unit, which is fixedly mounted on the base, is used to emit a laser beam to the reflecting component;

[0013] A photoelectric detection component, which is fixedly installed on the base, is used to receive the optical signal formed by the laser beam reflected by the reflective component, and can convert the optical signal into an electrical signal.

[0014] The signal processing unit is used to receive the electrical signal output by the photoelectric detection component, process it through an algorithm corresponding to the characteristics of the optical signal, and then calculate and output the tilt angle value.

[0015] As a further improvement of this application, the reflecting component is a plane mirror, the photoelectric detection component is a photoelectric detection array, the plane mirror is used to receive the laser beam emitted by the laser emitting unit and reflect it directionally to the photoelectric detection array; the photoelectric detection array is used to receive the laser beam reflected by the plane mirror and detect the change in the position of the laser spot formed by the laser beam on the photoelectric detection array.

[0016] As a further improvement of this application, the signal processing unit uses a center positioning algorithm and a Gaussian fitting algorithm to calculate the center of the laser spot to obtain laser spot displacement data, and the laser spot displacement data and the tilt angle satisfy the following relationship:

[0017]

[0018] Wherein, y1 is the position of the laser spot on the photoelectric detection array after reflection of the laser beam when the gravity sensing element is in a vertical state; y2 is the position of the laser spot on the photoelectric detection array when the gravity sensing element is tilted at an angle α; L is the horizontal distance from the horizontal axis to the photoelectric detection array; H is the height from the horizontal axis to the reference line, with the horizontal line where the reflection point of the laser beam on the plane mirror is located when the gravity sensing element is in a vertical state as the reference line; β is the angle between the incident laser beam and the reference line; γ is the angle between the incident laser beam and the plane mirror after the gravity sensing element is tilted.

[0019] As a further improvement of this application, the laser beam emitted by the laser emitting unit is an invisible laser beam or a visible laser beam, and the laser spot size formed on the photodetector array by the laser collimation module is between 100μm and 300μm; the photodetector array is a CMOS array with a pixel size of 10μm.

[0020] As a further improvement of this application, the high-precision tilt measuring device based on optical principles also includes an auxiliary reflector, which is fixedly installed on the base and located on the laser reflection path between the plane reflector and the photoelectric detection array, for reflecting the laser beam reflected by the plane reflector back onto the photoelectric detection array.

[0021] As a further improvement of this application, the laser emitting unit includes a laser and a beam expanding and collimating optical component for generating a uniform collimated surface light source; the reflecting component is an integrated grating reflector with a grating structure integrated on its surface; the photoelectric detection component includes a fixed grating and a photoresistor, the fixed grating is fixedly installed on the base and located on the reflection path of the integrated grating reflector, for interacting with the grating image formed by the integrated grating reflector to generate moiré fringes; the photoresistor is disposed on the plane of the moiré fringes for detecting the light intensity signal when the moiré fringes move.

[0022] As a further improvement of this application, the signal processing unit is electrically connected to the photoresistor and is used to convert the light intensity signal into a periodic electrical signal and count the period N of the electrical signal. The period N and the displacement δ of the grating image when the tilt angle of the integrated grating mirror is α satisfy the following relationship: N=δ / P; where P is the period of the grating structure on the surface of the integrated grating mirror; at the same time, the tilt angle α and the displacement δ of the grating image satisfy the following relationship:

[0023]

[0024] Wherein, L is the horizontal distance from the horizontal axis to the fixed grating; H is the height from the horizontal axis to the reference line when the gravity sensing element is in a vertical state, and the horizontal line where the reflection point of the laser beam on the integrated grating mirror is located; β is the angle between the incident laser beam and the reference line; γ is the angle between the incident laser beam and the integrated grating mirror when the gravity sensing element is tilted.

[0025] As a further improvement of this application, the signal processing unit includes an amplification and filtering circuit, a waveform shaping circuit, and a processor connected in sequence. The amplification and filtering circuit is used to amplify the light intensity signal and filter out noise. The waveform shaping circuit is used to convert the amplified and filtered light intensity signal into a standard square wave. The processor is used to count the periods of the standard square wave and calculate the tilt angle α based on the period N.

[0026] As a further improvement of this application, the gravity sensing element is a pendulum body, and a windproof cover for shielding against wind vibration disturbance is provided on its outer side; a three-dimensional adjustable positioning platform is provided on the base, and the laser emitting unit and the photoelectric detection component are both installed on the three-dimensional adjustable positioning platform.

[0027] This application also provides a high-precision tilt angle measurement method based on optical principles, implemented using the high-precision tilt angle measurement device based on optical principles as described above, including the following steps:

[0028] S1, by adjusting the position of each component in the high-precision tilt measuring device based on optical principles to calibrate the optical path, when the gravity sensing element is in a vertical state, the laser beam emitted by the laser emitting unit is reflected by the reflecting component to the photoelectric detection component, and the reference parameters corresponding to the light signal received by the photoelectric detection component are recorded;

[0029] S2, When the base tilts with the object being measured, the gravity sensing element swings around the horizontal axis under its own weight, and drives the reflective component rigidly fixed to the gravity sensing element to deflect synchronously.

[0030] S3, after the reflective component deflects, the optical signal formed by the reflected laser beam changes accordingly, and the photoelectric detection component receives the changed optical signal and converts it into a corresponding electrical signal;

[0031] S4, the signal processing unit receives the electrical signal, processes the electrical signal according to the algorithm corresponding to the characteristics of the optical signal, calculates and outputs the tilt angle value of the measured object.

[0032] The beneficial effects of this application are:

[0033] 1. This application constructs a core architecture comprising a base, a gravity-sensitive element, a reflective component, a laser emitting unit, a photoelectric detection assembly, and a signal processing unit. Each component has a clear division of labor and works in concert, providing a stable and reliable structural foundation for high-precision tilt measurement. The gravity-sensitive element, through a design of a high-sensitivity, low-friction bearing that allows free oscillation around a horizontal axis, can accurately respond to minute changes in the direction of gravity, providing a sensitive mechanical sensing basis for tilt detection. The follow-up design of the reflective component and the gravity-sensitive element achieves a seamless connection between mechanical sensitivity and optical conversion, ensuring a direct correlation between tilt angle changes and changes in the reflected light path. The interconnected design captures minute tilt angle changes, avoiding signal distortion caused by relative displacement between components, and providing a stable and accurate physical basis for subsequent optical inspection. The collaborative design of the laser emission unit, photoelectric detection component, and signal processing unit realizes a complete detection link from laser emission to optical signal reception to electrical signal processing to tilt angle output. It forms a closed loop from mechanical sensing, optical transmission to signal processing, significantly improving the detection and resolution capability of minute tilt angle changes, achieving high precision and high stability in angle measurement, and possessing a compact structure, making it suitable for various application scenarios such as precision engineering and geological monitoring.

[0034] 2. This application significantly extends the propagation path of the laser beam within the device by incorporating an auxiliary reflector. This makes the displacement of the laser spot on the photoelectric detection array more sensitive to minute changes in the measured tilt angle, thereby effectively improving the device's detection capability and measurement accuracy for subtle tilt angle variations. Simultaneously, the folding optical path structure facilitates miniaturization of the device, achieving higher laser spot displacement sensitivity within a limited space. This design advantage is particularly suitable for engineering and research scenarios requiring extremely high resolution for micro- and nano-angle changes.

[0035] 3. This application innovatively proposes a tilt measurement scheme based on moiré fringes. This scheme integrates grating fringes on the surface of an integrated grating mirror. The interaction between the fixed grating and the grating image formed by the integrated grating mirror generates stable moiré fringes. The change in light intensity signal caused by the movement of the moiré fringes is directly detected by a photoresistor. The complex image recognition problem is simplified to photoelectric signal period counting. High-precision digital measurement can be achieved using only a single photoresistor, which greatly simplifies the system structure, reduces hardware costs and data processing load, and significantly improves the anti-interference capability and operational reliability of the device. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of a first embodiment of the high-precision tilt measuring device based on optical principles of this application;

[0038] Figure 2 This is a schematic diagram illustrating the tilt measurement principle of Embodiment 1 of the high-precision tilt measurement device based on optical principles of this application.

[0039] Figure 3 This is a flowchart illustrating the steps of the high-precision tilt measurement method based on optical principles in this application.

[0040] Figure 4 This is a schematic diagram illustrating the tilt measurement principle of Embodiment 2 of the high-precision tilt measurement device based on optical principles of this application.

[0041] Figure 5 This is a schematic diagram of the structure of Embodiment 3 of the high-precision tilt measuring device based on optical principles of this application;

[0042] Reference numerals: 1. Base; 2. Gravity-sensitive element; 3. Laser emitting unit; 4. Plane reflector; 5. Photoelectric detection array; 6. Auxiliary reflector; 7. Integrated grating reflector; 8. Fixed grating; 9. Photoresistor. Detailed Implementation

[0043] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0045] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0046] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0047] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0048] Example 1: See Figure 1 This embodiment provides a high-precision tilt measurement device based on optical principles, including: a base 1, a gravity sensing element 2, a reflective component, a laser emitting unit 3, a photoelectric detection component, and a signal processing unit.

[0049] Among them, the base 1, which serves as the supporting foundation of the entire tilt measuring device, can be integrally formed using high-strength materials, and the base 1 is equipped with a bearing mounting seat for installing bearings.

[0050] The gravity sensing element 2 is rotatably mounted on the bearing mounting seat of the base 1 via a bearing. When the base 1 tilts with the object being measured, the gravity sensing element 2 can swing freely around a horizontal axis under its own gravity, thereby returning to a vertical distribution state, so as to respond to the change in the tilt angle of the object being measured in real time.

[0051] The horizontal axis described in this application coincides with the axis of the bearing. Preferably, the bearing is a high-sensitivity, low-friction bearing to improve response sensitivity.

[0052] Furthermore, the reflective component is rigidly fixed to the gravity-sensitive element 2, and the reflective component and the incident direction of the laser beam are precisely aligned during initial setup to ensure optical path stability. When the gravity-sensitive element 2 swings freely around the horizontal axis, the gravity-sensitive element 2 will drive the reflective component rigidly fixed to it to deflect synchronously, that is, the reflective component always changes with the attitude of the gravity-sensitive element 2.

[0053] It should be noted that the center of gravity of the overall structure consisting of the gravity sensing element 2, the reflective component and related components connected to the bearing is on the same vertical line as the center of gravity of the gravity sensing element 2, so that in the free state, the gravity sensing element 2 and the reflective component are both distributed in the vertical direction.

[0054] In this application, the reflective component has a laser beam reflection function. The reflective component has two selection modes: one is the plane reflector 4 used in this embodiment, and the other is the integrated grating reflector 7 with a grating structure integrated on the surface used in Embodiment 3 below. When the reflective component selects to use the plane reflector 4 to reflect the laser beam, it can form a laser spot on the photoelectric detection component; when the reflective component selects to use the integrated grating reflector 7 to reflect the laser beam, a grating image can be formed through the surface-integrated grating structure, thereby adapting to different photoelectric detection requirements.

[0055] Furthermore, the laser emitting unit 3 is fixedly mounted on the base 1 and is used to emit a laser beam to the reflecting component.

[0056] The photoelectric detection component is also fixedly installed on the base 1 and is located on the reflection path of the laser beam by the reflector. It is used to receive the optical signal formed after the laser beam is reflected by the reflector and can convert the optical signal into an electrical signal that can be processed by the subsequent unit, i.e., the signal processing unit.

[0057] The signal processing unit receives the electrical signal output by the photoelectric detection component, processes it using an algorithm corresponding to the characteristics of the optical signal, and then calculates the output tilt angle value.

[0058] This application constructs a core architecture comprising a base 1, a gravity-sensitive element 2, a reflective component, a laser emitting unit, a photoelectric detection assembly, and a signal processing unit. Each component has a clearly defined function and works in concert, providing a stable and reliable structural foundation for high-precision tilt measurement. The gravity-sensitive element 2, through its design of a high-sensitivity, low-friction bearing that freely swings around a horizontal axis, can accurately respond to minute changes in the direction of gravity, providing a sensitive mechanical sensing basis for tilt detection. The follow-up design of the reflective component and the gravity-sensitive element 2 achieves a seamless connection between mechanical sensitivity and optical conversion, ensuring direct correlation between tilt angle changes and changes in the reflected light path. The interconnected design can capture extremely small tilt angle changes, avoiding signal distortion caused by relative displacement between components, and providing a stable and accurate physical basis for subsequent optical inspection. The collaborative design of the laser emission unit 3, photoelectric detection component and signal processing unit realizes a complete detection link of laser emission - optical signal reception - electrical signal processing - tilt angle output. It forms a closed loop from mechanical sensing, optical transmission to signal processing, which significantly improves the detection and resolution capability of small tilt angle changes, realizes high precision and high stability of angle measurement, and has the characteristics of compact structure, which is suitable for the use needs of various application scenarios such as precision engineering and geological monitoring.

[0059] Preferably, the gravity sensing element 2 is a high-precision pendulum, and a windproof cover is provided on its outside to shield it from air disturbances and vibrations, so as to avoid the high-precision pendulum from erroneous swinging due to non-tilt factors, thus ensuring the sensitivity and accuracy of the measurement.

[0060] It is worth mentioning that a three-dimensional adjustable positioning platform is set on the base 1, and the laser emitting unit 3 and the photoelectric detection component are all mounted on the three-dimensional adjustable positioning platform. The three-dimensional adjustable positioning platform provides a precise installation and adjustment benchmark for the gravity sensing element 2, the laser emitting unit 3, and the photoelectric detection component, facilitating the optical path calibration of each component. The above-mentioned optimized structural design further improves the measurement consistency and environmental adaptability of the device, enabling the device to stably output high-precision measurement results in different usage scenarios.

[0061] It should be noted that the three-dimensional adjustable positioning platform used in this application is a conventional existing technology component in the field of precision measurement. Its core function is to provide a stable installation reference and multi-dimensional adjustment freedom for the laser emitting unit 3, the photoelectric detection component, and the auxiliary reflector 6 described later, so as to achieve precise alignment and calibration of the optical path. This three-dimensional adjustable positioning platform typically has translation adjustment functions in the X, Y, and Z directions and angle fine-tuning functions around each axis. Its structure and working principle are well known to those skilled in the art. For example, a commonly used manual precision positioning platform in this field can be used without additional modifications to its specific structure to meet the usage requirements of this application.

[0062] In this application, the laser beam emitted by the laser emitting unit 3 is either an invisible laser beam or a visible laser beam, and the laser emitting unit 3 is equipped with a laser collimation module. The laser collimation module ensures that the size of the laser spot formed on the photoelectric detection array 5 is between 100μm and 300μm. The incident angle of the laser beam emitted by the laser emitting unit 3 can be adjusted according to actual needs.

[0063] In this embodiment, the reflecting component is a plane mirror 4, also known as a common mirror. The plane mirror 4 is used to receive the laser beam emitted by the laser emitting unit 3 and directionally reflect it to the photoelectric detection component. Further, in this embodiment, the photoelectric detection component is a photoelectric detection array 5, specifically a CMOS array with a pixel size of 10μm. Through a high-precision signal acquisition circuit, it can achieve μm-level detection of the laser spot displacement, improving angular resolution. The photoelectric detection array 5 is installed at the end of the optical path to receive the laser beam reflected by the plane mirror 4 and detect changes in the position of the laser spot formed on the photoelectric detection array 5.

[0064] It is important to emphasize that the distance between the plane mirror 4 and the photoelectric detection array 5 is adjustable and should be at least greater than 8 cm. The detection accuracy can be changed by adjusting this distance. Similarly, when the high-precision pendulum is in a vertical position, the distance between the horizontal line where the laser beam is reflected on the plane mirror 4 is located and the reference line is also adjustable. The detection accuracy can be changed by adjusting this distance.

[0065] In this embodiment, the signal processing unit uses a center localization algorithm and a Gaussian fitting algorithm to calculate the center of the laser spot, and removes background noise using the algorithm to obtain laser spot displacement data. The laser spot displacement data and the tilt angle satisfy the following formula:

[0066]

[0067] Where y1 is the position of the laser spot on the photoelectric detection array 5 after reflection of the laser beam when the gravity sensing element 2 is in a vertical state; y2 is the position of the laser spot on the photoelectric detection array 5 when the gravity sensing element 2 is tilted at an angle α (which is also the tilt angle of the plane mirror 4); L is the horizontal axis ( Figure 2 The horizontal distance from point O to the photoelectric detection array 5; taking the horizontal line where the laser beam is reflected on the plane mirror 4 when the gravity sensing element 2 is in a vertical state as the reference line, H is the height of the horizontal axis from the reference line; β is the angle between the incident laser beam and the reference line; γ is the angle between the incident laser beam and the plane mirror 4 after the gravity sensing element 2 is tilted.

[0068] In this embodiment, the signal processing unit employs a combination of center positioning and Gaussian fitting algorithms. This approach accurately extracts the center position of the laser spot, effectively filters out spot offset interference caused by noise, and improves the accuracy and stability of spot position detection. Simultaneously, a mathematical relationship between spot displacement data and tilt angle values ​​is established, providing a clear theoretical basis and traceability for the measurement results, ensuring that the device can stably achieve high-precision tilt angle measurements at the level of one-thousandth of a degree.

[0069] It should be noted that the center positioning algorithm and Gaussian fitting algorithm used by the signal processing unit in this embodiment are both conventional signal processing techniques known in the art. They have been widely used in related technical fields such as optical detection and spot positioning. Their core function is to achieve accurate extraction of the target position and noise suppression through mature digital analysis logic. This application does not improve the above algorithms themselves, but rather, based on its own designed overall device architecture of "gravity sensitive element-optical reflection path-photoelectric detection component", it rationally selects such conventional algorithms to process the collected spot position signal. Through the coordinated cooperation of the algorithm and the device structure, it achieves accurate calculation of the spot center, thereby ensuring high accuracy and high stability of tilt angle measurement. The application of the above conventional algorithms does not affect the innovation of this application in terms of device structure and scheme integration.

[0070] See Figure 2 and Figure 3 This application also provides a high-precision tilt angle measurement method based on optical principles, implemented using the high-precision tilt angle measurement device based on optical principles described in Embodiment 1, including the following steps:

[0071] S1, the positions of each component (including but not limited to the laser emitting unit 3 and the photoelectric detection array 5) in the high-precision tilt measuring device based on optical principles are adjusted by a three-dimensional adjustable positioning platform to calibrate the optical path. The angle between the incident laser beam and the reference line is adjusted to β. When the gravity sensitive element 2 is in a vertical state, the laser beam emitted by the laser emitting unit 3 is reflected by the reflective component to the photoelectric detection array 5. The reference parameters corresponding to the light signal received by the photoelectric detection array 5 are recorded, that is, the reference position y1 of the laser spot.

[0072] S2, when the base 1 or the entire device tilts with the object being measured, the gravity sensing element 2 swings slightly around the horizontal axis due to its own gravity, and drives the plane mirror 4, which is rigidly fixed on it, to deflect synchronously.

[0073] S3, after the plane mirror 4 deflects, the optical signal formed by its reflected laser beam changes accordingly. At this time, the position of the laser spot on the photodetector array 5 is displaced, denoted as y2. The photodetector array 5 receives this changed optical signal and converts it into a corresponding electrical signal.

[0074] S4, the signal processing unit receives electrical signals, collects the position information of the laser spot on the photoelectric detection array 5, uses a Gaussian fitting algorithm to locate the center of the laser spot, and removes background noise through the algorithm to extract the most realistic displacement signal.

[0075] Finally, the signal processing unit substitutes the parameters into Formula 1 to calculate and output the tilt angle value α of the measured object.

[0076] Example 2: See Figure 4 The difference between this embodiment and Embodiment 1 is that the high-precision tilt measuring device based on optical principles also includes an auxiliary reflector 6. The auxiliary reflector 6 is fixedly installed on the three-dimensional adjustable positioning platform of the base 1 and is located on the laser reflection path between the plane reflector 4 and the photoelectric detection array 5. The auxiliary reflector 6 is used to reflect the laser beam emitted after being reflected by the plane reflector 4 again, so that the final laser spot formed by the laser beam projected on the photoelectric detection array 5 arrives after multiple reflections.

[0077] Furthermore, by adjusting the relative position between the auxiliary reflector 6 and the plane reflector 4, the laser propagation distance can be flexibly set according to the actual measurement sensitivity requirements and spatial size constraints.

[0078] This embodiment significantly extends the propagation path of the laser beam within the device by incorporating an auxiliary reflector 6. This makes the displacement of the laser spot on the photoelectric detection array 5 more sensitive to minute changes in the measured tilt angle, thereby effectively improving the device's detection capability and measurement accuracy for subtle tilt angle variations. Simultaneously, the folding optical path structure facilitates miniaturization of the device, achieving higher laser spot displacement sensitivity within a limited space. This design advantage is particularly suitable for engineering and research scenarios requiring extremely high resolution for micro- and nano-angle changes.

[0079] After adding auxiliary reflector 6, the relationship between the laser spot displacement data and the tilt angle changes, as detailed below:

[0080]

[0081] Wherein, y3 is the position of the laser beam on the photoelectric detection array 5 after being reflected twice by the plane mirror 4 and the auxiliary mirror 6 when the gravity sensing element 2 is in a vertical state; y4 is the position of the laser spot on the photoelectric detection array 5 when the tilt angle of the gravity sensing element 2 is α (which is also the tilt angle of the plane mirror 4); the other variables are the same as in Example 1.

[0082] This embodiment, through experimental calibration and theoretical derivation, optimizes and matches the six parameters of the auxiliary reflector (such as size, reflection angle, and installation position) with measurement sensitivity and detection accuracy, thereby achieving a comprehensive improvement in the overall performance of the system. It significantly expands the application range of the device in the field of ultra-high resolution tilt angle detection and provides technical support for high-performance tilt angle measurement under complex environments and limited space conditions.

[0083] Example 3: See Figure 5 The difference between this embodiment and Embodiment 1 is that the reflective component is an integrated grating reflector 7, and the photoelectric detection component includes a fixed grating 8 and a photoresistor 9.

[0084] Specifically, the integrated grating reflector 7 employs vacuum deposition and photolithography to fabricate a precision diffraction grating structure with a grating period of p on its optical plane. This allows the integrated grating reflector 7 to simultaneously perform beam reflection and grating imaging functions, reducing assembly errors between the independent grating and the reflector, and simplifying the device structure. The integrated grating reflector 7 is rigidly fixed to the gravity-sensitive element 2, ensuring that its grating lines remain horizontal at all times.

[0085] Furthermore, the fixed grating 8 is manufactured using the same process, and the grating line period of the fixed grating 8 is the same as that of the integrated grating reflector, both set to P. The fixed grating 8 is fixedly installed on the base 1 and located on the reflection path of the integrated grating reflector 7, and the grating lines of the fixed grating 8 and the grating lines of the integrated grating reflector have a small angle, so that the grating image formed by the fixed grating 8 and the integrated grating reflector 7 interacts to produce moiré fringes.

[0086] Furthermore, the photoresistor 9 is disposed on the moiré fringe imaging surface to detect the periodic light intensity signal caused by the movement of the moiré fringes. Preferably, the photosensitive surface size of the photoresistor 9 is precisely matched to a single moiré fringe period to ensure optimal signal contrast.

[0087] In this embodiment, the signal processing unit is electrically connected to the photoresistor 9 and is used to convert the light intensity signal into a periodic electrical signal and count its period N.

[0088] When the gravity-sensitive element 2 is tilted, the reflected grating image is displaced, and the moiré fringes also move accordingly. At this time, the photoresistor 9 detects a period of light intensity change of N. Since one period of movement of the moiré fringes corresponds to one period of movement of the grating image, the period of movement of the grating image is also N.

[0089] When the period N is tilted at an angle α to the integrated grating mirror 7 (or the gravity sensing element 2 is tilted at an angle α), the displacement δ of the grating image satisfies Formula 2: N=δ / P, where P is the period of the grating structure on the surface of the integrated grating mirror 7.

[0090] Similarly to the embodiment, the tilt angle α and the displacement δ of the grating image satisfy the following formula:

[0091]

[0092] Given L=8cm, H=50μm, β=60°, and α=0.001°, the displacement of the grating image can be calculated according to Formula 3 as δ=11.17μm, which is greater than the detectable pixel value of 10μm.

[0093] Where L is the horizontal distance from the horizontal axis to the fixed grating 8; H is the height from the horizontal axis to the reference line when the gravity sensing element 2 is in a vertical state, and the horizontal line where the reflection point of the laser beam on the integrated grating mirror 7 is located; β is the angle between the incident laser beam and the reference line; and γ is the angle between the incident laser beam and the integrated grating mirror 7 after the gravity sensing element 2 is tilted.

[0094] By combining Equations 2 and 3 above, a precise correspondence can be established between the movement of the moiré fringes and the change in the tilt angle of the gravity-sensitive element 2, and the tilt angle α can be obtained.

[0095] The signal processing unit in this embodiment adopts an integrated four-level processing architecture.

[0096] Specifically, the signal processing unit includes an amplification and filtering circuit, a waveform shaping circuit, and a processor, which are connected in sequence to the photoresistor 9.

[0097] The amplification and filtering circuit is used to amplify the light intensity signal and filter out noise. It uses an instrumentation amplifier INA128 to form a differential amplifier circuit with a gain of 60dB and integrates a 0.1Hz-10kHz bandpass filter to effectively suppress low-frequency drift and high-frequency noise.

[0098] The waveform shaping circuit is used to convert the amplified and filtered light intensity signal into a standard square wave. It is based on the LM393 voltage comparator to build a Schmitt trigger. By utilizing the inherent hysteresis characteristics of the Schmitt trigger, the irregular analog signal after pre-amplification can be shaped into a standard square wave signal with steep edges and stable amplitude. The hysteresis voltage of the trigger is designed to be adjustable from 50-200mV. Users can flexibly adjust it according to the actual lighting conditions of the application scenario (such as strong light and weak light environments), ensuring that even in complex environments with large light fluctuations, it can still stably output a square wave signal synchronized with the movement of moiré fringes, significantly improving the environmental adaptability of the system.

[0099] The processor includes a counting unit and a calculation output unit. The counting unit is used to count the cycles of a standard square wave, and the calculation output unit calculates the tilt angle α based on the cycle N.

[0100] In this embodiment, the processor is specifically an STM32F103 microcontroller, and the counting unit is a 16-bit timer / counter built into the processor. By configuring the timer to rise-edge triggered counting mode, it accurately counts the conditioned standard square wave signal to obtain the period N corresponding to the movement of the moiré fringes. The counting resolution of this 16-bit timer / counter can reach ±1 / 2 period, which can sensitively capture the minute movement of the moiré fringes and provide high-precision raw counting data for tilt angle calculation. The calculation output unit is a floating-point unit (FPU) built into the processor. This unit has fast floating-point operation capabilities and can quickly derive and calculate the tilt angle α of the measured object based on the system's inherent parameters such as the grating period p preset in the microcontroller, combined with the period N output by the counting unit, using the formulas two and three mentioned above; finally, the digital result is output through the SPI interface.

[0101] This application innovatively proposes a tilt measurement scheme based on moiré fringes. This scheme integrates grating fringes on the surface of an integrated grating reflector 7. Stable moiré fringes are generated through the interaction between a fixed grating 8 and the grating image formed by the integrated grating reflector 7. A photoresistor 9 directly detects changes in light intensity signal caused by the movement of the moiré fringes, simplifying the complex image recognition problem to photoelectric signal periodic counting. High-precision digital measurement can be achieved using only a single photoresistor 9, replacing the "imaging-analysis" mode of traditional moiré fringe schemes that rely on linear or area array image sensors. This significantly simplifies the system structure and reduces hardware costs and data processing load. This innovative design not only retains the advantages of the original technical solution but also significantly improves the device's anti-interference capability and operational reliability, broadening the application scenarios of moiré fringe technology in the field of tilt measurement.

[0102] The same or similar parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments.

[0103] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-precision tilt measuring device based on optical principles, characterized in that, include: Base (1); A gravity-sensitive element (2) is rotatably mounted on the base (1) via a bearing, and when the base (1) tilts with the object being measured, the gravity-sensitive element (2) can swing freely around a horizontal axis under its own weight; wherein the horizontal axis coincides with the axis of the bearing. The reflective component is rigidly fixed to the gravity-sensitive element (2). The reflective component has a laser beam reflection function, or the reflective component has a laser beam reflection function and a grating structure integrated on its surface to reflect the laser beam to form a grating image. A laser emitting unit (3) is fixedly installed on the base (1) and is used to emit a laser beam to the reflecting component; The photoelectric detection component is fixedly installed on the base (1) and is used to receive the optical signal formed by the laser beam reflected by the reflective component and to convert the optical signal into an electrical signal. The signal processing unit is used to receive the electrical signal output by the photoelectric detection component, process it through an algorithm corresponding to the characteristics of the optical signal, and then calculate and output the tilt angle value. The reflective component is a plane mirror (4), and the photoelectric detection component is a photoelectric detection array (5). The plane mirror (4) is used to receive the laser beam emitted by the laser emitting unit (3) and reflect it in a directional manner to the photoelectric detection array (5). The photoelectric detection array (5) is used to receive the laser beam reflected by the plane mirror (4) and detect the change in the position of the laser spot formed on the photoelectric detection array (5). The signal processing unit uses a center positioning algorithm and a Gaussian fitting algorithm to calculate the center of the laser spot to obtain laser spot displacement data, and the laser spot displacement data and the tilt angle satisfy the following relationship: ； Wherein, y1 is the position of the laser spot on the photoelectric detection array (5) after the laser beam is reflected when the gravity sensing element (2) is in a vertical state; y2 is the position of the laser spot on the photoelectric detection array (5) when the gravity sensing element (2) is tilted at an angle of α; L is the horizontal distance from the horizontal axis to the photoelectric detection array (5); taking the horizontal line where the reflection point of the laser beam on the plane mirror (4) is located when the gravity sensing element (2) is in a vertical state as the reference line, H is the height from the horizontal axis to the reference line; β is the angle between the incident laser beam and the reference line; γ is the angle between the incident laser beam and the plane mirror (4) after the gravity sensing element (2) is tilted.

2. The high-precision tilt measuring device based on optical principles according to claim 1, characterized in that, The laser beam emitted by the laser emitting unit (3) is either an invisible laser beam or a visible laser beam, and the laser beam is collimated by the laser collimation module so that the size of the laser spot formed on the photoelectric detection array (5) is between 100μm and 300μm. The photoelectric detection array (5) is a CMOS array with a pixel size of 10μm.

3. The high-precision tilt measuring device based on optical principles according to claim 1, characterized in that, It also includes an auxiliary reflector (6), which is fixedly installed on the base (1) and located on the laser reflection path between the plane reflector (4) and the photoelectric detection array (5), and is used to reflect the laser beam reflected by the plane reflector (4) back to the photoelectric detection array (5).

4. The high-precision tilt measuring device based on optical principles according to claim 1, characterized in that, The laser emitting unit (3) includes a laser and a beam expanding and collimating optical component for generating a uniform collimated surface light source; The reflective component is an integrated grating reflector (7), whose surface is integrated with a grating structure; The photoelectric detection component includes a fixed grating (8) and a photoresistor (9). The fixed grating (8) is fixedly installed on the base (1) and located on the reflection path of the integrated grating mirror (7), and is used to interact with the grating image formed by the integrated grating mirror (7) to generate moiré fringes. The photoresistor (9) is disposed on the plane where the moiré fringes are located, and is used to detect the light intensity signal when the moiré fringes move.

5. The high-precision tilt measuring device based on optical principles according to claim 4, characterized in that, The signal processing unit is electrically connected to the photoresistor (9) and is used to convert the light intensity signal into a periodic electrical signal and count the period N of the electrical signal. The period N and the displacement δ of the grating image when the tilt angle of the integrated grating mirror (7) is α satisfy the following relationship: N=δ / P; where P is the period of the grating structure on the surface of the integrated grating mirror (7); at the same time, the tilt angle α and the displacement δ of the grating image satisfy the following relationship: ； Wherein, L is the horizontal distance from the horizontal axis to the fixed grating (8); with the horizontal line where the reflection point of the laser beam on the integrated grating reflector (7) is located when the gravity sensing element (2) is in a vertical state as the reference line, H is the height from the horizontal axis to the reference line; β is the angle between the incident laser beam and the reference line; γ is the angle between the incident laser beam and the integrated grating reflector (7) after the gravity sensing element (2) is tilted.

6. The high-precision tilt measuring device based on optical principles according to claim 5, characterized in that, The signal processing unit includes an amplification and filtering circuit, a waveform shaping circuit, and a processor connected in sequence. The amplification and filtering circuit is used to amplify the light intensity signal and filter out noise. The waveform shaping circuit is used to convert the amplified and filtered light intensity signal into a standard square wave. The processor is used to count the periods of the standard square wave and calculate the tilt angle α based on the period N.

7. The high-precision tilt measuring device based on optical principles according to claim 1, characterized in that, The gravity-sensitive element (2) is a pendulum, and a windproof cover for shielding against wind vibration disturbance is provided on the outside of the pendulum; And / or, a three-dimensional adjustable positioning platform is provided on the base (1), and the laser emitting unit (3) and the photoelectric detection component are both installed on the three-dimensional adjustable positioning platform.

8. A high-precision tilt angle measurement method based on optical principles, characterized in that, This is achieved using the high-precision tilt measuring device based on optical principles as described in any one of claims 1 to 7, and includes the following steps: S1, by adjusting the position of each component in the high-precision tilt measuring device based on optical principle to calibrate the optical path, when the gravity sensitive element (2) is in a vertical state, the laser beam emitted by the laser emitting unit (3) is reflected by the reflective component to the photoelectric detection component, and the reference parameters corresponding to the light signal received by the photoelectric detection component are recorded; S2, when the base (1) tilts with the object being measured, the gravity sensing element (2) swings around the horizontal axis under its own gravity, and drives the reflective component rigidly fixed on the gravity sensing element to deflect synchronously. S3, after the reflective component deflects, the optical signal formed by the reflected laser beam changes accordingly, and the photoelectric detection component receives the changed optical signal and converts it into a corresponding electrical signal; S4, the signal processing unit receives the electrical signal, processes the electrical signal according to the algorithm corresponding to the characteristics of the optical signal, calculates and outputs the tilt angle value of the measured object.

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