CN109932112A - Two-dimensional surface array force tactile sensing method based on optical fiber distributed sensing - Google Patents

Abstract

The two-dimensional surface array power tactilely-perceptible method based on distributed fiber-optic sensor that the present invention relates to a kind of, used sensor is chirped fiber grating two dimension power tactile sensing face battle array, this face battle array is formed by connecting by the chirped fiber grating at more distributions in one plane different location with single mode optical fiber, the reflected spectrum wavelengths range of different chirped fiber gratings is all different, any position on the axial dimension of each chirped fiber grating is corresponding with the actual wavelength size in its reflection spectrum bandwidth, and the wavelength of corresponding points changes when by ambient pressure, to realize the point distributed awareness of power tactile.Utilize the laser signal of the adjustable swept light source output of wavelength linear, each chirped fiber grating and Faraday mirror of chirped fiber grating two dimension power tactile sensing face battle array are successively incident on through coupler, the reflected light of chirp grating and the reflected light of Faraday mirror are input to photoelectric conversion module again through photo-coupler.

Description

Two-dimensional surface array force tactile sensing method based on optical fiber distributed sensing

technical field

The invention belongs to the technical field of tactile sensing, and is mainly applied to the force tactile sensing technology of robots or intelligent manufacturing. The invention relates to a sensing method for realizing the force-tactile sensation of a two-dimensional space plane array by using an optical fiber chirped grating as a pressure sensitive element.

Background technique

Tactile sensing is to simulate human skin perception and quantitatively realize the sense of surface force between the sensing unit (such as: manipulator, bionic tentacles) and the object. At present, with the rapid development of my country's artificial intelligence robot technology, the accuracy and stability of many domestic robot parts can already replace imports. However, there is still one technology that still relies on imports, that is, tactile sensor technology.

The difficulty of tactile sensing technology lies in the high-density spatial resolution of force touch: traditional electronic tactile sensing technology integrates high-density array sensing elements in a small space. The coupling disturbance makes it more difficult to output accurately.

Domestic patent applications and authorizations for tactile sensing are basically concentrated in the field of flexible electronic devices, such as: a bionic flexible tactile sensing array based on a combination of piezoresistive and capacitive types (CN102589759A), a high-sensitivity tactile sensor (CN108185997A), a positive Tetrahedral three-dimensional force flexible tactile sensor array (CN206281590U), a new type of electronic tactile skin (CN109029800A) and so on.

However, in comparison, the research results and industrialization of Japan, Europe and the United States in the field of electronic tactile sensing are in a leading position in the world. The technical parameters of articles and patent designs are higher than those of my country, such as South Korea's patent on medical tactile sensing (KR1914979). -B1), Japanese patents on flexible tactile panels and tactile fingers (JP2018180621-A, JP2018175459-A) and so on. It can be seen that in the pursuit of original technology, latecomers must bypass the relevant patent protection of the forerunners. Unless a significantly better solution is found, it is likely that the threshold for technology achievement will be raised by bypassing patents. Therefore, how to bypass the layout of foreign countries in the field of tactile sensing and break through the limitations of the current measurement parameters from the optical fiber distributed sensing technology is the purpose of the patent of the present invention.

SUMMARY OF THE INVENTION

In view of the above problems, the purpose of the present invention is to bypass the technical means of tactile sensing of electronic device arrays, overcome the problems of the size of traditional piezoelectric device sensor arrays, mutual signal coupling interference, etc., and utilize the high-density space of chirped fiber grating pressure sensitive devices. The characteristics of distributed strain resolution enable the perception of pressure directionality in two-dimensional surface arrays. The technical solution is as follows:

A two-dimensional surface array force tactile sensing method based on optical fiber distributed sensing. The sensor used is a chirped fiber grating two-dimensional force tactile sensing surface array. The chirped fiber gratings are connected by single-mode fibers. The wavelength range of the reflection spectrum of different chirped fiber gratings is different. Any position on the axial dimension of each chirped fiber grating is the actual wavelength within the reflection spectrum bandwidth. The size corresponds to, and the wavelength of the corresponding point changes when subjected to external pressure, so as to realize the point distribution perception of force touch. The laser signal output by the swept light source with linearly adjustable wavelength is incident on each chirped fiber grating and the Faraday rotator of the chirped fiber grating two-dimensional force tactile sensing area array in turn through the coupler, and the reflected light of the chirped grating The reflected light from the Faraday rotator and the Faraday rotator is then input to the photoelectric conversion module through the optical coupler. The reflected wavelength of the spatial point position of the chirped grating and the reflected wavelength of the Faraday rotator undergo heterodyne interference in the photoelectric conversion module. The frequency signal is collected by the data acquisition module, and the beat frequency signal of different frequencies scanned and sampled synchronously with the frequency sweep light source locates the corresponding spatial point of the chirped grating.

The present invention has the following advantages due to taking the above technical solutions:

(1) Compared with the existing electronic tactile sensing scheme, the present invention realizes the spatial force tactile resolution by means of optical wavelength resolution, and the spatial resolution reaches the sub-millimeter level, which is higher than the parameters of the currently known electronic tactile sensing scheme. An order of magnitude higher than the human tactile resolution parameter.

(2) From the perspective of optical fiber distributed sensing, the present invention utilizes the one-to-one correspondence between the wavelength value in the reflection spectrum bandwidth of the chirped fiber grating and the spatial size and position, and realizes the optical measurement of high-density spatial force tactile perception.

(3) The present invention utilizes the force tactile measurement capability of high-density spatial points, and combines the numerical analysis of the distribution of pressure signals in two-dimensional space to realize the measurement of two-dimensional force distribution in space from the perspective of optical measurement.

(4) The present invention senses in the optical band and measures in the electrical band, taking into account the sensitivity of optical sensing and the convenience of electrical measurement.

Description of drawings

Figure 1 Chirped fiber grating one-dimensional force tactile sensing unit (X direction)

Fig. 2 Two-dimensional force-tactile sensing area array (XY direction) of chirped fiber grating encapsulated by flexible resin material.

Fig.3 Simulation diagram of tactile two-dimensional force distribution of chirped fiber grating

Figure 4. Structure diagram of chirped fiber grating tactile sensor signal demodulation system

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

The chirped fiber grating linear one-dimensional sensing unit with 10cm axial size and 0.25mm radial size is designed and manufactured in Figure 1. The reflection spectrum of the chirped fiber grating is centered at 1550nm wavelength and the bandwidth is 2nm (that is, the reflection spectrum wavelength range from 1549nm to 1551nm) broadband optical signal. Any position on the 10cm axial dimension of the chirped fiber grating corresponds to the actual wavelength within the 2nm bandwidth of the reflection spectrum, and the wavelength of the corresponding point changes when subjected to external pressure, which can realize the point distribution perception of force touch. Therefore, the measurement resolution of the reflection wavelength of the chirped fiber grating determines the spatial point resolution of the chirped fiber grating as a force tactile sensor within the range of 10 cm of fiber length, and a one-dimensional spatial point resolution of 0.5 mm can theoretically be achieved.

In Figure 2, the three chirped fiber gratings shown in Figure 1 are connected with ordinary single-mode fibers. The axial size of the three chirped fiber gratings is 10 cm (X direction), the radial size is 0.25 mm, and the wavelength range of the reflection spectrum is 1549nm-1551nm, 1551nm-1553nm, 1553nm-1555nm. The arrangement spacing of chirped fiber grating is 0.5mm (Y direction), forming a 10cm*2.25mm chirped fiber grating tactile sensing surface array. The chirped fiber grating tactile sensing area array was encapsulated into a two-dimensional planar tactile sensing device with epoxy resin (mixed by Araldite DBF and ARADUR HY 951 in a ratio of 5:1, Young's modulus 2.9 GPa) (see Figure 2). ). When subjected to external pressure, the wavelength of the corresponding point of the chirped fiber grating tactile sensing surface array changes, which can realize the surface distribution perception of force touch.

Figure 3 is the simulation of the two-dimensional force distribution of the chirped fiber grating tactile sensor under the action of external force.

Figure 4 shows the structure of the chirped fiber grating tactile sensing signal measurement system. The laser signal output by the swept frequency light source with linearly adjustable wavelength is incident on the chirped fiber grating tactile sensing surface array and the Faraday rotator respectively through the coupler. The reflected light of the grating and the reflected light of the Faraday rotator are then input to the photoelectric conversion module through the optical coupler. For each chirped grating, the reflected wavelength of the chirped grating’s one-dimensional space point position and the reflected wavelength of the Faraday rotator mirror undergo heterodyne interference in the photoelectric conversion module. The different frequency beat signals sampled by the time-synchronized scanning of the light source locate the one-dimensional space points of the chirped grating. When the chirped grating is stressed at a spatial point, the fiber grating at that point produces an instant dispersion time delay, which makes the beat frequency signal of the corresponding point change instantaneously, and the force information of this point is obtained through time-frequency analysis.

Claims (1)

1. A two-dimensional surface array force tactile sensing method based on optical fiber distributed sensing, the sensor used is a chirped fiber grating two-dimensional force tactile sensing surface array, and this surface array is composed of multiple roots distributed on a plane. The chirped fiber grating at the position is connected by a single-mode fiber. The reflection spectrum wavelength range of different chirped fiber gratings is different. Any position on the axial dimension of each chirped fiber grating and its reflection spectrum bandwidth are different. The actual wavelength corresponds to the size, and the wavelength of the corresponding point changes when subjected to external pressure, so as to realize the point distribution perception of force touch. The laser signal output by the swept light source with linearly adjustable wavelength is incident on each chirped fiber grating and the Faraday rotator of the chirped fiber grating two-dimensional force tactile sensing area array in turn through the coupler, and the reflected light of the chirped grating The reflected light from the Faraday rotator and the Faraday rotator is then input to the photoelectric conversion module through the optical coupler. The reflected wavelength of the spatial point position of the chirped grating and the reflected wavelength of the Faraday rotator undergo heterodyne interference in the photoelectric conversion module. The frequency signal is collected by the data acquisition module, and the beat frequency signal of different frequencies scanned and sampled synchronously with the frequency sweep light source locates the corresponding spatial point of the chirped grating.