Single flexible optical fiber sensor for detecting dual degrees of freedom and preparation method thereof

Abstract

The single flexible optical fiber sensor for detecting dual degrees of freedom and the preparation method thereof of the present invention realize the high-precision optical fiber signal acquisition of the dual degrees of freedom of the proximal phalanx, and achieve the design purpose of retaining the precise characteristics of optical fiber detection and greatly reducing the volume of the sensor when detecting dual degrees of freedom relative to other detection methods. The single flexible optical fiber sensor for detecting dual degrees of freedom includes a U-shaped optical modulation module and a profile-incident flexible optical fiber arranged in the U-shaped optical modulation module; the U-shaped optical modulation module includes an upper cover and a lower shell connected to each other, the upper cover has a semicircular upper cover groove similar to a U-shape and a positioning cylinder protruding downward, and an upper cover notch is formed at one side end of the semicircular upper cover groove; the lower shell has a semicircular lower shell groove similar to a U-shape and a concave positioning hole located in the semicircular lower shell groove, and a lower shell notch is arranged on one side of the lower shell; when the positioning cylinder is inserted into the positioning hole, the upper cover and the lower shell cooperate with each other for positioning and connection and fixation.

Description

Technical Field

[0001] The present application proposes a sensor for detecting dual degrees of freedom using a single flexible optical fiber and a preparation method thereof, and belongs to the field of hand motion capture. Background Art

[0002] The fiber optic sensors currently used for capturing and detecting hand motion information usually only have single-degree-of-freedom detection performance. The main reason for this is that traditional flexible fiber optic sensors can only detect the stretching and bending of the optical fiber, but cannot distinguish the specific direction of the bending and stretching. For the dual degrees of freedom of the proximal phalanx of the hand, only the up and down bending of the fingers can be detected, but not the left and right swinging. In addition, the left and right swinging of the fingers also causes certain interference to the up and down bending signals, resulting in inaccurate detection results.

[0003] In view of this, this patent application is proposed. Summary of the invention

[0004] The single flexible optical fiber sensor for detecting two degrees of freedom and its preparation method described in the present invention aim to solve the problems existing in the above-mentioned prior art and propose a new type of single flexible optical fiber sensor for detecting two degrees of freedom, as well as a processing method for preparing and assembling its various components, in order to realize high-precision optical fiber signal acquisition of the two degrees of freedom of the proximal phalanx, so as to achieve the design purpose of retaining the precise characteristics of optical fiber detection and greatly reducing the size of the sensor.

[0005] To achieve the above-mentioned design purpose, the single flexible optical fiber sensor for detecting dual degrees of freedom includes a U-shaped optical modulation module and a profile-incident flexible optical fiber arranged in the U-shaped optical modulation module; the U-shaped optical modulation module includes an upper cover and a lower shell connected to each other, the upper cover has a semicircular upper cover groove similar to a U-shape and a downwardly protruding positioning cylinder, and an upper cover notch is formed at one side end of the semicircular upper cover groove; the lower shell has a semicircular lower shell groove similar to a U-shape and an inwardly concave positioning hole located in the semicircular lower shell groove, and a lower shell notch is arranged on one side of the lower shell; when the positioning cylinder is inserted into the positioning hole, the upper cover and the lower shell cooperate with each other for positioning and connection and fixation.

[0006] Furthermore, the notch of the upper cover and the notch of the lower shell are nested with each other to form a positioning hole for fixing and installing the first laser diode; after the upper cover and the lower shell are assembled and installed, the two semicircular grooves inside them are combined to form a wave-like through groove, which has a U-shaped shape.

[0007] Furthermore, the through groove comprises a U-shaped curved surface formed by wavy line tracks of at least three concave portions.

[0008] Based on the above-mentioned single flexible optical fiber sensor structure design for detecting dual degrees of freedom, its preparation method includes the following implementation steps:

[0009] Step 1: Production

[0010] 1.1. The upper cover and lower shell of the U-shaped optical modulation module are processed and manufactured respectively;

[0011] 1.2. Prepare C-type auxiliary module;

[0012] 1.3. Prepare profile-incident flexible optical fiber;

[0013] High light transmittance stretch magic elastic material is used as the fiber core and PDMS is used as the cladding;

[0014] Step 2: Assembly

[0015] Apply glue to the semicircular upper cover groove and the semicircular lower shell groove respectively, and place the cross-sectional incident flexible optical fiber into them;

[0016] After the upper cover and the lower shell are assembled and installed, the wave line tracks of at least three concave parts of the through groove form a U-shaped curved surface;

[0017] A first laser diode is fixedly installed at a positioning hole formed by the mutual nesting of the upper cover notch and the lower shell notch, and a cross-section portion of the cross-section incident flexible optical fiber is aligned with the first laser diode;

[0018] Step 3: Connect;

[0019] Assembling a circuit module including an amplifier circuit and a second laser diode and a third laser diode;

[0020] Use LM345 chip as operational amplifier to connect adjustable resistor to form an amplifier circuit;

[0021] The second laser diode and the third laser diode are respectively welded to the two ends of the front part of the amplifying circuit to form a circuit module;

[0022] Establish photoelectric signal connection between the U-shaped optical modulation module and the circuit module.

[0023] Furthermore, the process of preparing the profile-incident flexible optical fiber includes: first, cutting a section of high-transmittance stretch magic elastic material of appropriate length according to the needs, and then placing the middle of the section of material in the C-shaped groove of the C-shaped auxiliary module, and fixing the two together with a small amount of adhesive; then, mixing the PDMS stock solution and the curing agent in a ratio of 10:1, and stirring for 3 to 6 minutes; then, placing it in a vacuum defoaming machine for 8 to 12 minutes of vacuum defoaming treatment; spraying the treated PDMS liquid thin layer evenly on the above-mentioned high-transmittance stretch magic elastic material, placing it in a drying oven at a temperature of 60 to 80 degrees for half an hour to an hour of drying treatment to cure the PDMS coating on its surface; repeating the above operation again until the PDMS cladding reaches a thickness of 0.15 to 0.25 mm; finally, removing the C-shaped auxiliary module, cleaning the adhesive with high-concentration alcohol to expose part of the fiber core, and completing the preparation process of the profile-incident flexible optical fiber.

[0024] In summary, the advantages of the single flexible optical fiber sensor for detecting dual degrees of freedom and the preparation method thereof are:

[0025] On the one hand, the present application converts the up and down bending and left and right swinging of the finger into four different forms of light signal changes through a cross-sectional incident flexible optical fiber and a U-shaped optical modulation module, and then converts the light signal into an easy-to-use voltage signal through a circuit module, thereby achieving accurate detection of the two degrees of freedom of the proximal phalanx through a single flexible optical fiber.

[0026] On the other hand, the present application achieves a significant reduction in the size of the sensor while being able to flexibly and easily implement dual-degree-of-freedom detection. In addition to meeting the dual-degree-of-freedom detection of the proximal phalanx, it can also be used in other situations where dual-degree-of-freedom detection is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the upper cover of the U-shaped optical modulation module;

[0028] Figure 2 It is a schematic diagram of the lower shell of the U-shaped optical modulation module;

[0029] Figure 3 A perspective view of a U-shaped optical modulation module after the upper cover and the lower shell are assembled and installed;

[0030] Figure 4 This is a schematic diagram of a C-type auxiliary module;

[0031] Figure 5 This is a schematic diagram of the detection of the sensor near the fingers of the hand after the circuit module is installed; DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] Embodiment 1, as Figures 1 to 5 As shown, the present application proposes a novel single flexible optical fiber sensor for detecting dual degrees of freedom, which includes a U-shaped optical modulation module 1 and a profile-incident flexible optical fiber arranged in the U-shaped optical modulation module 1 .

[0034] The U-shaped optical modulation module is used to convert the action signal generated by a flexible optical fiber for dual degrees of freedom (such as bending a finger up and down, or swinging left and right) into four different optical signal changes through its internal structural characteristics, which are then received and analyzed by a subsequently connected circuit module, thereby achieving accurate and comprehensive detection of the dual degrees of freedom of the finger by a single flexible optical fiber.

[0035] Specifically, the U-shaped optical modulation module 1 includes an upper cover 10 and a lower shell 20 connected to each other, the upper cover 10 has a semicircular upper cover groove 11 similar to a U shape and two positioning cylinders 12 protruding downward with a diameter of about 1 mm, and an upper cover notch 13 is formed at one side end of the semicircular upper cover groove 11, wherein the diameter of the semicircular upper cover groove 11 is about 1.4 mm;

[0036] The lower shell 20 has a semicircular lower shell groove 21 similar to a U shape and two concave positioning holes 22 located in the semicircular lower shell groove 21, and a lower shell notch 23 is provided on one side of the lower shell 20; wherein, the inner diameter of the positioning hole 22 is about 1 mm, wherein the diameter of the semicircular lower shell groove 21 is also about 1.4 mm; when the two positioning cylinders 12 are inserted into the positioning holes 22, the upper cover 10 and the lower shell 20 cooperate with each other for positioning and connection and fixation, and the upper cover notch 13 and the lower shell notch 23 are mutually nested to form a positioning hole for fixing and installing the first laser diode 4;

[0037] After the upper cover 10 and the lower shell 20 are assembled, the two semicircular grooves inside the upper cover 10 and the lower shell 20 are assembled to form a through groove 30 which is similar to a wave as a whole. Figure 3 A U-shaped shape is clearly observed in the perspective view.

[0038] The through groove 30 comprises a U-shaped curved surface formed by wave-line tracks of at least three concave portions, and the optical fiber signal collection section formed along the U-shaped curved surface forms a light modulation area of ​​the optical fiber signal.

[0039] Based on the structural characteristics of the above-mentioned sensor, the method for preparing a sensor for detecting dual degrees of freedom with a single flexible optical fiber includes the following implementation steps:

[0040] Step 1: Production

[0041] 1.1. The upper cover 10 and the lower shell 20 of the U-shaped optical modulation module 1 are processed and manufactured respectively;

[0042] 1.2. Prepare C-type auxiliary module 2;

[0043] The 3D model was drawn using solidworks and prepared using a 3D printer using PLA material; wherein the main body of the C-type auxiliary module 2 is a structure with a C-shaped cross section, an inner diameter of about 1 mm, a length of 1.5 mm, and a wall thickness of 0.2 mm;

[0044] 1.3. Preparation of profile-incident flexible optical fiber,

[0045] High light transmittance stretch magic elastic material is used as the fiber core, and PDMS is used as the cladding; wherein the high light transmittance stretch magic elastic material is a rope-shaped material with a diameter of 1 mm, and the PDMS is initially in a liquid state;

[0046] The preparation process includes: firstly, cutting a section of high-transmittance stretch magic elastic material of appropriate length according to the requirements, and then placing the middle of the section of material in the C-shaped groove of the C-shaped auxiliary module 2, and fixing the two together with a small amount of adhesive; then, mixing the PDMS stock solution and the curing agent in a ratio of 10:1, stirring for 5 minutes; then, placing it in a vacuum defoaming machine for 10 minutes of vacuum defoaming treatment;

[0047] The treated PDMS liquid thin layer is evenly sprayed on the above-mentioned high-transmittance stretch magic elastic material, and placed in a drying oven at a temperature of 70 degrees for one hour to cure the PDMS coating on its surface; the above operation is repeated again until the PDMS coating reaches a thickness of 0.2 mm;

[0048] Finally, the C-type auxiliary module 2 is removed, and the adhesive is cleaned with high-concentration alcohol to expose part of the fiber core, thus completing the preparation process of the cross-section-incident flexible optical fiber.

[0049] Step 2: Assembly

[0050] Apply K704 silica gel to the semicircular upper cover groove 11 and the semicircular lower shell groove 21 respectively, and place the cross-sectional incident flexible optical fiber therein;

[0051] After the upper cover 10 and the lower shell 20 are assembled and installed, the wave line tracks of at least three concave parts of the through groove 30 form a U-shaped curved surface;

[0052] The first laser diode 4 is fixedly installed at the positioning hole formed by the upper cover notch 13 and the lower shell notch 23 being nested with each other, and the cross-section part of the cross-section incident flexible optical fiber is aligned with the first laser diode 4;

[0053] Step 3: Connect;

[0054] Assembling a circuit module 3 including an amplifier circuit and a second laser diode 5 and a third laser diode 6;

[0055] An LM345 chip is used as an operational amplifier to connect an adjustable resistor to form an amplifier circuit, and the amplifier circuit is used to amplify the tiny electrical signals emitted by the second laser diode 5 and the third laser diode 6;

[0056] The second laser diode 5 and the third laser diode 6 are respectively welded to the two ends of the front part of the above-mentioned amplifier circuit to form a circuit module 3;

[0057] The U-shaped optical modulation module 1 and the circuit module 3 establish a photoelectric signal connection.

[0058] In the above preparation process, after the flexible optical fiber is fixed, the light emitted by the laser diode 1 will be emitted into the flexible optical fiber through the cross-section of the flexible optical fiber, and then pass through the U-shaped wave-like curved surface inside the U-shaped optical modulation module 1 and be emitted from the two ends of the optical fiber through the rear end holes of the semicircular upper cover groove 11 and the semicircular lower shell groove 21;

[0059] The emitted light enters the second laser diode 5 and the third laser diode 6 connected to the circuit module 3 , so that the second laser diode 5 and the third laser diode 6 convert the optical signal into an electrical signal respectively.

[0060] like Figure 5 As shown, the U-shaped optical modulation module 1 is placed above the proximal phalanx of the index finger, and the circuit module 3 is fixed at the position of the proximal phalanx close to the metacarpal bone. When the finger is in the middle and straight state, the two parts of the flexible optical fiber extending from the U-shaped optical modulation module 1 are both under a small tensile force, and the light output at both ends of the optical fiber is the same.

[0061] When the finger begins to bend, both ends of the flexible optical fiber will be stretched at the same time, and the tensile force will be converted into pressure on the flexible optical fiber through the U-shaped wave groove inside the U-shaped optical modulation module 1, so that the light intensity at both ends of the flexible optical fiber will be reduced by the same amount at the same time. When the finger is straightened, the tension on the flexible optical fiber will be reduced, so that the pressure of the U-shaped wave groove inside the U-shaped optical modulation module 1 on the flexible optical fiber is reduced, so that the light intensity at both ends of the flexible optical fiber will be increased by the same amount at the same time.

[0062] When the finger swings left and right, the two ends of the flexible optical fiber will show one end being stretched and the other end being contracted. When the finger swings to the left, the tension on the left flexible optical fiber will decrease, and the tension on the right flexible optical fiber will increase. With the U-shaped wave groove inside the U-shaped optical modulation module 1, the light intensity on the left end increases, and the light intensity on the right end decreases. Similarly, when the finger swings to the right, the light intensity on the left end of the flexible optical fiber decreases, and the light intensity on the right end increases.

[0063] As described above, similar technical solutions can be derived from the solutions given in the drawings and descriptions, and they all still fall within the scope of rights of the technical solutions of the present invention.

Claims

1. A sensor for detecting two degrees of freedom using a single flexible optical fiber, characterized in that: Includes U-shaped optical modulation module and settings A profile-injected flexible optical fiber in a U-shaped optical modulation module; The U-shaped optical modulation module comprises an upper cover and a lower shell connected to each other, the upper cover has a semicircular upper cover groove similar to a U shape and a positioning cylinder protruding downward, and an upper cover notch is formed at one side end of the semicircular upper cover groove; the lower shell has a semicircular lower shell groove similar to a U shape and a concave positioning hole located in the semicircular lower shell groove, and a lower shell notch is arranged on one side of the lower shell; when the positioning cylinder is inserted into the positioning hole, the upper cover and the lower shell cooperate with each other to be positioned and connected and fixed; The profile-incident flexible optical fiber has a U-shape similar to the mounting surface of the U-shaped optical modulation module; Assembling the profile-incident flexible optical fiber in the U-shaped optical modulation module, wherein the profile portion of one end of the profile-incident flexible optical fiber is aligned with the first laser diode fixedly mounted between the upper cover and the lower shell; The other end of the cross-section incident flexible optical fiber establishes optical signal connections with the second laser diode and the third laser diode of the circuit module respectively.

2. The single flexible optical fiber dual-degree-of-freedom sensor according to claim 1, characterized in that: The upper cover notch and the lower shell notch are nested with each other to form a positioning hole for fixing and installing the first laser diode; After the upper cover and the lower shell are assembled and installed, the two semicircular grooves inside are combined to form a wave-like through groove, and the through groove has a U-shaped shape.

3. The single flexible optical fiber dual-degree-of-freedom sensor according to claim 2, characterized in that: The through groove comprises a U-shaped curved surface formed by wave-line tracks of at least three concave portions.

4. The method for preparing a sensor for detecting two degrees of freedom using a single flexible optical fiber as claimed in any one of claims 1 to 3, characterized in that: The implementation steps include: Step 1: Production 1.

1. The upper cover and lower shell of the U-shaped optical modulation module are processed and manufactured respectively; 1.

2. Prepare C-type auxiliary module; 1.

3. Prepare profile-incident flexible optical fiber; High light transmittance stretch magic elastic material is used as the fiber core and PDMS is used as the cladding; Step 2: Assembly Apply glue to the semicircular upper cover groove and the semicircular lower shell groove respectively, and place the cross-sectional incident flexible optical fiber into them; After the upper cover and the lower shell are assembled and installed, the wave line tracks of at least three concave parts of the through groove form a U-shaped curved surface; A first laser diode is fixedly installed at a positioning hole formed by the mutual nesting of the upper cover notch and the lower shell notch, and a cross-section portion of the cross-section incident flexible optical fiber is aligned with the first laser diode; Step 3: Connect; Assembling a circuit module including an amplifier circuit and a second laser diode and a third laser diode; Use LM345 chip as operational amplifier to connect adjustable resistor to form an amplifier circuit; The second laser diode and the third laser diode are respectively welded to the two ends of the front part of the amplifying circuit to form a circuit module; Establish photoelectric signal connection between the U-shaped optical modulation module and the circuit module.

5. The method for preparing a sensor for detecting two degrees of freedom using a single flexible optical fiber according to claim 4, characterized in that: The process of preparing the profile-incident flexible optical fiber includes: firstly, cutting a section of high-transmittance stretchmagic elastic material of appropriate length according to the requirements, then placing the middle of the section of material in the C-shaped groove of the C-shaped auxiliary module, and fixing the two together with a small amount of adhesive; then, mixing the PDMS stock solution and the curing agent in a ratio of 10:1, stirring for 3 to 6 minutes; then, placing it in a vacuum defoaming machine for 8 to 12 minutes of vacuum defoaming treatment; The treated PDMS liquid thin layer is evenly sprayed on the above-mentioned high-transmittance stretch magic elastic material, and placed in a drying oven at a temperature of 60 to 80 degrees for half an hour to an hour to cure the PDMS coating on its surface; the above operation is repeated again until the PDMS coating reaches a thickness of 0.15 to 0.25 mm; Finally, the C-type auxiliary module is removed, and the adhesive is cleaned with high-concentration alcohol to expose part of the fiber core, thus completing the preparation process of the cross-section-incident flexible optical fiber.

Images