SK289077B6 - Optical sensor of the magnitude and operation place of external force - Google Patents

Abstract

Optical sensor of the magnitude and location of external force consists of two or more optical media (2), of the pistons (3) transmitting an external force simultaneously on optical media (2) and from the housing (4) in which the optical media (2) are embedded, wherein the optical parameters of at least one of the optical medias (2) depend on a coordinate measured along the optical media (2). An optical sensor of the magnitude and location of the external force can be used, for example, for weighing cars in motion and makes it possible to determine the place of passage, the speed as well as the distribution of the load.

Description

The field of technology

The invention relates to an optical sensor for the size and location of the force. The invention falls into the field of measurement and sensor technology.

Current state of the art

Optical force sensors are devices that work on different physical principles. These devices make it possible to determine the magnitude of the applied force by using optical media whose optical transmission parameters depend on the magnitude of the applied force. The effect of the acting external force on the absorption coefficient (microbending losses), the change in the polarization of optical radiation, the change in the wavelength of the reflected optical radiation after passing through the Bragg grating and on the optical length of the environment (various types of optical interferometers) is most often used.

Optical sensors based on the use of these physical principles are currently developed and fairly widely used in various applications, which include determining the weight of cars. Usually, only one parameter is determined using optical sensors, namely the magnitude of the applied external force (SK 134-2018 U1 Device for measuring dynamic force using an optical fiber). If it is also necessary to determine the place of action of the external force, then another sensor is used to detect the place of action (CN101666660 (A) Vehicle load action position recognizing method based on fiber bragg grating sensing technology). When using a system consisting of several independent force sensors (KR100383818 (B1) System for weighing by fiber grating sensor), it is possible to determine, in addition to the size, the location of the applied force. In this case, the accuracy of determining the action of the force depends on the distance of the discrete elements used. The greater the number of elements, the more accurate is the determination of the external force, but at the same time, the construction of the system and the evaluation are more complicated. These shortcomings are eliminated by the optical sensor of the size and location of the external force presented in this application. The presented optical sensor of the size and location of the external force is not bound to a specific physical principle, so it can be implemented using optical sensors using the influence of the external force on various transmission parameters of the optical environment.

The essence of the invention

The optical sensor of the magnitude and location of the external force is realized by using two or more optical environments through which optical rays (waves) pass, and the transmission parameters of these environments depend on the magnitude of the external force acting on the optical environments, while at least one of these environments is such that the change of transfer parameters caused by an acting external force depends not only on the size of the acting force, but also on the place in which the force acts. These optical environments are arranged in such a way that an external force acts simultaneously on the used optical environments. Due to the different dependence of the transmission parameters of optical environments on the location of the external force, the optical state at the output of these environments is also different. The optical state is characterized by amplitude, phase and polarization, and all these characteristics can be detected by a suitable detector, so the dependence of any of these parameters on the magnitude of the applied force can be used to determine the magnitude of this force, and with the known dependence of the detected transfer parameter on the magnitude and location of the external forces in individual environments. Detection of the optical state at the output of individual environments enables the location and magnitude of the acting external force to be determined.

Optical environments through which optical rays (waves) propagate can be realized as waveguides (optical fibers), light guides or objects with dimensions many times greater than the wavelength of the light used, in which optical rays propagate as in an unlimited environment (rods) .

The property of optical sensors to simultaneously determine the magnitude of the force and the place of its action is manifested as an advantage, for example, in determining the weight of cars as they move. In addition, when the sensor is placed at a suitable angle against the direction of movement of the vehicle, a single sensor makes it possible to determine not only the weight, but also the speed of the passing car, as well as the distribution of the weight of the load.

Overview of images on drawings

In fig. 1 shows the circuit diagram of the optical sensor of the size and location of the external force, and in fig. 2 is a schematically drawn section of an optical sensor.

Examples of implementation of the invention

The optical sensor of the magnitude and location of the external force presented in this example is based on the dependence of the refractive index of optical waves of different linear polarizations in polymethyl methacrylate on its deformation at a given location.

The schematic assembly of the connection of the sensor of the size and location of the external force is shown in fig. 1. Optical radiation from sources 1 of linearly polarized monochromatic light is coupled into optical environments 2, which in this example are realized by two rods 2a and 2b of rectangular cross-section of polymethyl methacrylate. In this case, the rod 2a has the same cross-section throughout its length, and the rod 2b has the same thickness as the rod 2a, and its width increases uniformly with the distance from the beginning of the rod. After passing through the rods 2a and 2b, the light rays are connected to two detectors 5a and 5b of the polarization plane, consisting of light intensity detectors and polarization filters. The electric signal from the detectors 5a and 5b of the polarization plane is fed by coaxial cables 6 to the electronic evaluation unit 7. The arrangement of rods 2a and 2b in the housing 4 of the optical sensor for determining the magnitude and location of the external force is shown in fig. 2. and is such that the action of the external force on both rods 2a and 2b is equal and simultaneous. As a result of the action of the external force acting on the rods 2a and 2b through the pistons 3, the orientation of the polarization plane of the light passing through the rods 2a and 2b changes depending on the magnitude of their deformation, so it is determined by the magnitude of the applied force and the width of the rods 2a and 2b in place, which is determined by the location of the external force.

With a linear increase in the width of the rod 2b from a width ho = 5 mm to a width ho + Δh = 10 mm at the end of the rod 2b, the deformation of the rod 2b caused by the force acting on its end is half compared to the deformation that the force would cause if it was applied at the beginning of rod 2b, so that the rotation of the polarization plane will be half that of the action of the same force at the beginning of rod 2b.

In general, when the same force is applied at a distance x from the beginning of the rod 2b, the rotation of the polarization plane φ( x) is equal to φ( xo ).(1 + (Δ h.x)/(ho.l)), where l is the length of the rod and φ ( xo) is the rotation of the polarization plane when the force acts on the beginning of rod 2b. The rotation of the polarization plane in rod 2a is independent of the location of the external force and is equal to φ( xo ), because the cross-sections of rods 2a and 2b are the same at the beginning of rods 2a and 2b. This makes it possible to determine the magnitude and location of the external force from the knowledge of the orientation of the polarization plane at the output of both rods 2a and 2b.

Industrial applicability

An optical sensor consisting of several optical environments with different parameters depending on the place of application of the force can be used to determine the size and place of the applied force, which is used in measurement and sensor technology, for example, for weighing moving vehicles.

List of relationship tags

- sources of linearly polarized monochromatic light

- optical environments

2a - rod

2b - rod

- pistons

- housing and - polarization plane detector

5b - polarization plane detector

- coaxial cables

- electronic evaluation unit

Claims (2)

1. An optical sensor of the size and location of the external force, consisting of sources (1) of linearly polarized monochromatic light, from two or more optical environments (2), pistons (3) for the simultaneous application of an external force to the optical environments (2), housings ( 4), in which optical environments (2) are stored, polarization plane detectors (5) connected by coaxial cables (6) to an electronic evaluation unit (7), characterized in that the optical parameters of at least one of the optical environments (2) are dependent from the coordinate measured along the optical media (2). 2. An optical sensor of the magnitude and location of the external force according to claim 1 consisting of two optical environments (2a) and (2b) realized by two bars of rectangular cross-section of piezo-optically active material, characterized in that the width of at least one of the optical environments (2a) or (2b) is dependent on the coordinate measured along the optical environments (2a) and (2b).