Three-dimensional vector force measuring device and method based on light refractive index

Abstract

The invention belongs to the technical field of industrial measurement, and particularly relates to a three-dimensional vector force measuring device and method based on light refractive index, the device comprises a bottom disc, a top disc and measuring assemblies, the measuring assemblies are circumferentially and uniformly arranged and hinged between the bottom disc and the top disc, and the included angle between the adjacent measuring assemblies is 90 degrees. The measuring assembly comprises a closed type air pressure piston, the upper end and the lower end of the closed type air pressure piston are hinged to the top disc and the bottom disc respectively, the closed type air pressure piston is filled with a gas medium, and light-transmitting windows are formed in the two sides, close to the lower end face, of the closed type air pressure piston. A laser transmitter is arranged at one of the light-transmitting windows, the laser transmitter is connected with a laser generator through an optical fiber, and a measuring unit is arranged at the other light-transmitting window. According to the method, electricity is completely prevented from being used in a measurement area, and compared with a traditional electric bridge method, the risk of generating electric sparks is fundamentally eradicated, so that safety production is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial measurement, and in particular relates to a three-dimensional vector force measurement device and method based on the refractive index of light. Background Art

[0002] Mechanical processing and chemical production cannot be separated from the measurement of the force of the reactor or the corresponding mechanical parts, so as to facilitate the subsequent control of the feeding, mechanical operation and other processes. To meet such needs, the existing technologies for stress measurement mostly use the resistance change caused by metal deformation - the voltage or current change caused by the different resistance is measured by the bridge method to reflect the metal deformation, and then the stress caused by the deformation and stress comparison relationship can be known. This type of technology has three major disadvantages: First, there will inevitably be current, and if there is current, it is possible to generate electric sparks due to poor contact, and the generation of electric sparks can easily lead to extremely dangerous production accidents. However, in some large factories, especially in factories producing dangerous chemical products and in the use and manufacturing of precision instruments, open flames are strictly prohibited in most workshops. In this case, line aging, operating errors, poor contact, etc. are extremely dangerous safety hazards, and such reasons are not easy to troubleshoot. Second, the method of using the bridge method to measure the voltage or current change caused by different resistance to reflect metal deformation has a greater impact on the resistance value due to different temperatures. Measuring at different temperatures will affect the measurement accuracy, resulting in a large error.

[0003] On this basis, a second technology was developed - a stress sensor that optimizes the measurement by measuring the deformation size according to the change in the optical fiber measurement distance. This technology is based on the fact that the application of stress will cause the standard metal shell to deform, and the deformation of the metal shell will be reflected in the change of the optical fiber measurement distance. The disadvantages of this type of technology are: 1. If the measured unit or the mounting base shakes or the displacement of the measuring optical fiber caused by physical factors such as metal fatigue will bring a huge error relative to the metal deformation, and the measured data will be seriously inconsistent at this time. 2. If the optical fiber facing area, that is, the area where the optical path passes, has a high temperature, since most traditional measuring instruments are open media, their media will easily produce uneven medium density under high temperature, which will cause the propagation speed of light in the medium to change unstably and uncontrollably, thereby affecting the transmission time of light in the same path, and even due to the uneven density of the medium or the introduction of other debris, the light will be scattered and reflected, which will directly affect the measurement data and even directly cause the light path to be scattered, so that the light intensity does not meet the standard and there is no measurement data. 3. Since the system in the process of light propagation is not a closed system, in some special environments, other debris may be introduced or the expected medium environment may be changed, causing the light propagation speed to change, or even the light propagation path may change due to reflection. Therefore, in measurement devices, the impact of the environment on the measurement results cannot be ignored. 4. Due to the design defects of the standard metal parts, most of the previous stress sensors are only used to measure one-dimensional vector forces or even only the magnitude of the force but not its direction. Most of them can only measure the magnitude of pressure. When subjected to repeated tension and pressure, the aging and scrapping of the standard metal parts will be greatly accelerated, thereby greatly reducing the service life of the stress measurement device. Summary of the invention

[0004] In view of the above problems, the present invention provides a three-dimensional vector force measurement device and method based on the refractive index of light.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A three-dimensional vector force measuring device based on the refractive index of light comprises a bottom disc, a top disc and a measuring assembly, wherein there are three measuring assemblies which are evenly arranged in a circle and hinged between the bottom disc and the top disc, and the angle between adjacent measuring assemblies is 90°, and the measuring assembly comprises a closed pneumatic piston, wherein the upper end and the lower end of the closed pneumatic piston are respectively hinged to the top disc and the bottom disc, and the interior of the closed pneumatic piston is filled with a gas medium, and light-transmitting windows are provided on both sides of the closed pneumatic piston close to the lower end surface, and a laser emitter is provided at one of the light-transmitting windows, and the laser emitter is connected to a laser generator via an optical fiber, and a measuring unit is provided at another light-transmitting window, and the measuring unit is used to measure the refractive index of the laser, thereby reflecting the magnitude of the force.

[0007] Furthermore, the measuring unit comprises a photosensor fixed on another light-transmitting window, the photosensor is connected to an input end of a signal converter via an optical fiber, and an output end of the signal converter is connected to a computer.

[0008] Furthermore, a limiting platform is provided at the lower part of the inner cavity of the closed pneumatic piston, and the limiting platform is located above the light-transmitting window.

[0009] Furthermore, the laser emitter is installed on an angle adjustment mechanism, which includes an arc-shaped slide rail fixed on one side of a closed pneumatic piston, a slider is slidably arranged on the arc-shaped slide rail, a locking bolt is threadedly connected to one side of the slider, and the laser emitter is installed on the slider, and the laser emitter is always facing the same position of an adjacent light-transmitting window.

[0010] Furthermore, a ball joint is provided in the middle of the upper surface of the top disc, and the hinge center of the ball joint is the intersection point of the three measuring components.

[0011] A three-dimensional vector force measurement method based on the refractive index of light comprises the following steps: installing the three-dimensional vector force measurement device at the force point, and ensuring that the force point is located at the center of the top disk; before applying pressure, emitting laser light through a laser generator, and the laser light is transmitted from the laser transmitter into the interior of a closed air pressure piston through an optical fiber; a photosensitive sensor located on the other side receives the optical fiber passing through the gas medium, and outputs a detection signal to a signal converter; the detection signal is converted into an electrical signal by the signal converter, and input into a computer for conversion to obtain the initial pressure exerted on each closed air pressure piston; then applying pressure to the three-dimensional vector force measurement device, and the pressure is transmitted downward to the closed air pressure piston, The closed pneumatic piston is compressed after being subjected to force, and the concentration of the gas medium in the inner cavity of the closed pneumatic piston changes after being compressed, which in turn changes the refractive index of the light. The laser is emitted by the laser generator for detection again to obtain the actual pressure of each closed pneumatic piston after the force is applied. The difference between the actual pressure and the initial pressure is calculated to obtain the pressure applied to each closed pneumatic piston. The intersection of the extended lines of the axes of the three closed pneumatic pistons is taken as the origin, and the axes of the three closed pneumatic pistons are the x, y, and z axes to establish a spatial rectangular coordinate system. The positive direction is from the vertex along the edge downward, and the component loads are assigned to the x, y, and z coordinates respectively to obtain the three-dimensional vector force in space.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] The present invention is equipped with optical fiber for information transmission, avoiding the dependence of bridge method measurement on power supply. The optical fiber can transmit the changes of the light emission point received by the photosensitive sensor to the computer, and the corresponding stress value is converted by the computer. The use of electricity is completely avoided in the measurement area, and the risk of electric sparks is fundamentally eliminated compared with the traditional bridge method, thereby ensuring safe production;

[0014] Compared with the traditional bridge method, the error of the resistance value is greatly affected by different temperatures, which will cause relatively large errors at different temperatures; at the same time, the open medium of the stress sensor for measuring distance by optical fiber will easily produce the phenomenon of uneven medium density under high temperature, which will lead to unstable and uncontrollable changes in the propagation speed of light in the medium, making the measurement result completely unusable. The present invention adopts a standard measuring gas to reflect its metal deformation value, which improves the disadvantage that the resistance value is greatly affected by different temperatures. At the same time, the present invention sets a photosensitive sensor to measure the change of the optical fiber exit point. The sensitivity of the photosensitive sensor to light changes and the high-precision conduction of the optical fiber will ensure its accuracy;

[0015] The present invention replaces the optical path propagation medium with a closed gas medium. When the temperature changes, the gas medium in the closed gas pressure piston has more uniform and stable physical properties than the open medium gas. This improves the phenomenon that the medium of the traditional measuring instrument produces uneven density of the medium in the optical path under high temperature and the data is invalidated, greatly improving the accuracy and efficiency of the measurement.

[0016] The present invention can be applied to different scenarios through simple mechanical adjustments, such as adapting to different measurement ranges and accuracy requirements, and can also simultaneously meet the two detection methods of electronic computer display and inspector observation.

[0017] The structure of the present invention is simplified, and a single device can be used alone or in combination with multiple devices. The special triangular structure is used for combination. Compared with the shortcomings of most previous stress sensors that can only measure the magnitude of force, it meets the needs of three-dimensional measurement of the magnitude of force and its direction, and combines with a computer to meet the needs of measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention;

[0019] Figure 2 is a cross-sectional view of the closed gas pressure piston of the present invention;

[0020] Figure 3 This is a schematic diagram of the installation of the laser transmitter of the present invention;

[0021] Figure 4 For the present invention Figure 2 A partial enlarged view of the middle circle A;

[0022] Figure 5 It is a simplified structural diagram of the measuring assembly of the present invention;

[0023] Figure 6 is a schematic diagram of laser refraction of the present invention;

[0024] In the figure, there are bottom disc 1, top disc 2, measuring assembly 3, ball joint 4, closed pneumatic piston 301, light-transmitting window 302, laser emitter 303, limit table 304, arc slide rail 305, slider 306, locking bolt 307, photosensor 308, signal converter 309, computer 310, and laser generator 311. DETAILED DESCRIPTION

[0025] In order to further illustrate the technical solution of the present invention, the present invention is further described below through embodiments.

[0026] like Figures 1 to 3 As shown, a three-dimensional vector force measuring device based on the refractive index of light comprises a bottom disc 1, a top disc 2 and a measuring assembly 3, wherein the measuring assembly 3 has three components which are evenly arranged in a circle and hinged between the bottom disc 1 and the top disc 2, and the angle between adjacent measuring assemblies 3 is 90°, and the measuring assembly 3 comprises a closed pneumatic piston 301, wherein the upper end and the lower end of the closed pneumatic piston 301 are hinged to the top disc 2 and the bottom disc 1 respectively, and the closed pneumatic piston 301 is filled with a gas medium, and light-transmitting windows 302 are provided on both sides of the closed pneumatic piston 301 close to the lower end surface, and a laser emitter 303 is provided at one of the light-transmitting windows 302, and the laser emitter 303 is installed on an angle adjustment mechanism, and the angle adjustment mechanism comprises a laser beam fixed to the closed pneumatic piston 301. An arc-shaped slide rail 305 is provided on one side of 301, a slider 306 is slidably provided on the arc-shaped slide rail 305, a locking bolt 307 is threadedly connected to one side of the slider 306, the laser emitter 303 is installed on the slider 306, and the laser emitter 303 always faces the same position of the adjacent light-transmitting window 302, the laser emitter 303 is connected to the laser generator 311 through an optical fiber, a measuring unit is provided at the other light-transmitting window 302, the measuring unit is used to measure the refractive index of the laser, and then reflect the magnitude of the force, the measuring unit includes a photosensor 308 fixed on the other light-transmitting window 302, the photosensor 308 is connected to the input end of the signal converter 309 through an optical fiber, and the output end of the signal converter 309 is connected to the computer 310. A limit platform 304 is arranged at the lower part of the inner cavity of the closed pneumatic piston 301, and the limit platform 304 is located above the light-transmitting window 302. A ball joint 4 is arranged in the middle of the upper surface of the top disk 2, and the hinge center of the ball joint 4 is the intersection point of the three measuring components 3.

[0027] A three-dimensional vector force measurement method based on the refractive index of light comprises the following steps: installing the three-dimensional vector force measurement device at the force point, and ensuring that the force point is located at the center of the top disk 2; before applying pressure, emitting laser light through the laser generator 4; the laser light is transmitted through the optical fiber and then emitted from the laser emitter 303 into the interior of the closed gas pressure piston 301; a photosensitive sensor 308 located on the other side receives the optical fiber passing through the gas medium, and outputs a detection signal to a signal converter 309; the detection signal is converted into an electrical signal by the signal converter 309, and is input into a computer 310 for conversion to obtain the initial pressure exerted on each closed gas pressure piston 301; then applying pressure to the three-dimensional vector force measurement device, and the pressure is transmitted downward to the closed gas pressure piston 301; 01. The closed pneumatic piston 301 is compressed after being subjected to force. The concentration of the gas medium in the inner cavity of the closed pneumatic piston 301 changes after being compressed, which further changes the refractive index of the light. The laser generator 4 emits a laser for detection again to obtain the actual pressure of each closed pneumatic piston 301 after the force is applied. The difference between the actual pressure and the initial pressure is calculated to obtain the pressure applied to each closed pneumatic piston 301. The intersection of the extended lines of the axes of the three closed pneumatic pistons 301 is taken as the origin. The axes of the three closed pneumatic pistons 301 are the x, y, and z axes respectively to establish a spatial rectangular coordinate system. The positive direction is from the vertex along the edge downward, and the component loads are assigned to the x, y, and z coordinates respectively to obtain the three-dimensional vector force in space.

[0028] The present invention uses optical fiber to measure the refractive index instead of traditional optical fiber sensing to measure the deformation degree of the metal block, and then converts the measured value into stress. Because the incident point of the light path is fixed under the condition of fixed range and accuracy, and the light path exit point is measured by photosensitive sensing, the refractive index of the light can be inferred by measuring the light path exit point by photosensitive sensing. The change of stress is reflected in the pressure of the gas in the instrument and the mass fraction of the standard gas in the instrument. The change of mass fraction will affect the change of refractive index. Thus, the stress magnitude and direction at the measurement point can be inferred.

[0029] Specifically, when subjected to compressive stress, the volume of the gas component to be measured in the closed gas pressure piston 301 decreases, and the mass fraction of the gas component to be measured increases. Under normal circumstances, this will lead to an increase in the gas refractive index and an increase in the refractive power, which will cause the laser exit point to move downward; conversely, when subjected to tensile stress, the gas mass fraction decreases. Under normal circumstances, this will lead to a decrease in the gas refractive index and a decrease in the refractive power, which will cause the laser exit point to move upward. After the stress is applied, the refractive index changes, and the exit point changes. The change of the laser exit point is transmitted to the computer 310 by means of the photosensitive sensor 308. Because the incident point is fixed, the refractive index under this force can be easily calculated when the exit point is known. The gas mass fraction under such a situation can be calculated by combining different refractive indices with their corresponding gas mass fractions, and then the different pressures corresponding to different gas mass fractions; the pressure can be appropriately processed according to the specific size of the closed gas pressure piston 301 to obtain the magnitude of this stress. When the calculated pressure is less than the pressure at rest, it is tensile stress; otherwise, it is compressive stress.

[0030] like Figure 6 As shown in the figure, the specific calculation process of calculating the refractive index from the laser incident point is:

[0031]

[0032] In the formula: θ is the angle between the laser in the air and the axis of the closed pneumatic piston, θ1 is the angle between the laser in the light-transmitting window 302 and the axis of the closed pneumatic piston, n0 is the refractive index in the air, n1 is the refractive index of the light-transmitting window 302, d1 is the thickness of the light-transmitting window 302, r is the radius of the inner cavity of the closed pneumatic piston 301, and x is the distance between the projection of the laser incident point on the photosensor 308 and the actual landing point of the laser on the photosensor 308.

[0033] The specific calculation process of calculating pressure from refractive index is:

[0034]

[0035] Where: ρ is the gas density, μ r is the relative magnetic permeability of the gas, A ε =4πN A α / 3 represents the molar polarizability, N A is Avogadro's constant, α is the atomic polarizability, A μ =4πN A χ / 3 represents the molar magnetic susceptibility, χ is the atomic magnetic susceptibility, B ε is the second dielectric virial coefficient.

[0036] Calculate gas pressure from refractive index:

[0037]

[0038] Where P is the gas pressure, k B is the Boltzmann constant, T is the gas temperature, and B(T) is the second virial coefficient.

[0039] The initial pressure on the closed gas pressure piston 301 and the actual pressure after being stressed are calculated respectively by the conversion formula of refractive index and gas pressure, and the difference between the actual pressure and the initial pressure is calculated to obtain the pressure applied to the closed gas pressure piston 301.

[0040] The above shows and describes the main features and advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, 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, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0041] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A three-dimensional vector force measuring device based on the refractive index of light, characterized in that: The invention comprises a bottom disc (1), a top disc (2) and a measuring assembly (3). The measuring assembly (3) has three components which are evenly arranged in a circle and hinged between the bottom disc (1) and the top disc (2). The angle between adjacent measuring assemblies (3) is 90°. The measuring assembly (3) comprises a closed air pressure piston (301). The upper end and the lower end of the closed air pressure piston (301) are hinged to the top disc (2) and the bottom disc (1) respectively. The closed air pressure piston (301) is filled with a gas medium. Both sides of the closed air pressure piston (301) close to the lower end surface are provided with light-transmitting windows (302). A laser emitter (303) is provided at one of the light-transmitting windows (302). The laser emitter (303) is connected to a laser generator (311) via an optical fiber. A measuring unit is provided at another light-transmitting window (302). The measuring unit is used to measure the refractive index of the laser, thereby reflecting the magnitude of the force.

2. A three-dimensional vector force measuring device based on light refractive index according to claim 1, characterized in that: The measuring unit comprises a photosensor (308) fixed on another light-transmitting window (302), wherein the photosensor (308) is connected to an input end of a signal converter (309) via an optical fiber, and an output end of the signal converter (309) is connected to a computer (310).

3. The three-dimensional vector force measuring device based on the refractive index of light according to claim 1, characterized in that: A limiting platform (304) is provided at the lower part of the inner cavity of the closed air pressure piston (301), and the limiting platform (304) is located above the light-transmitting window (302).

4. The three-dimensional vector force measuring device based on the refractive index of light according to claim 1, characterized in that: The laser emitter (303) is mounted on an angle adjustment mechanism, and the angle adjustment mechanism comprises an arc-shaped slide rail (305) fixed on one side of a closed gas pressure piston (301), a slider (306) is slidably arranged on the arc-shaped slide rail (305), a locking bolt (307) is threadedly connected to one side of the slider (306), and the laser emitter (303) is mounted on the slider (306), and the laser emitter (303) always faces the same position of an adjacent light-transmitting window (302).

5. A three-dimensional vector force measuring device based on the refractive index of light, characterized in that: A ball joint (4) is provided in the middle of the upper surface of the top disc (2), and the hinge center of the ball joint (4) is the intersection point of the three measuring components (3).

6. A three-dimensional vector force measurement method based on the light refractive index based on the three-dimensional vector force measurement device of claim 2, characterized in that: The following steps are involved: The three-dimensional vector force measuring device is installed at the force bearing point, and the force bearing point is ensured to be located at the center of the top disk (2). Before applying pressure, a laser is emitted by a laser generator (4). The laser is transmitted through an optical fiber and then emitted from a laser emitter (303) into the interior of a closed air pressure piston (301). A photosensitive sensor (308) located on the other side receives the optical fiber passing through the gas medium and outputs a detection signal to a signal converter (309). The detection signal is converted into an electrical signal by the signal converter (309) and input into a computer (310) for conversion to obtain an initial pressure exerted on each closed air pressure piston (301); Then, pressure is applied to the three-dimensional vector force measuring device, and the pressure is transmitted downward to the closed air pressure piston (301). The closed air pressure piston (301) is compressed after being subjected to force, and the concentration of the gas medium in the inner cavity of the closed air pressure piston (301) changes after being compressed, thereby causing the refractive index of the light to also change. The laser generator (4) emits laser for detection again to obtain the actual pressure of each closed air pressure piston (301) after the force is applied. The difference between the actual pressure and the initial pressure is calculated to obtain the pressure applied to each closed air pressure piston (301). The intersection of the extended lines of the axes of the three closed air pressure pistons (301) is taken as the origin, and the axes of the three closed air pressure pistons (301) are respectively the x, y, and z axes to establish a spatial rectangular coordinate system. The positive direction is from the vertex along the edge downward, and the component loads are assigned to the x, y, and z coordinates respectively to obtain the spatial three-dimensional vector force.

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