CN112129449A - Robot finger multidimensional force sensing device and method based on fiber bragg grating - Google Patents
Robot finger multidimensional force sensing device and method based on fiber bragg grating Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
- G01L5/166—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using photoelectric means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
- G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
Abstract
The invention relates to a robot finger part multidimensional force sensing device and method based on fiber bragg gratings, which comprises a finger part shell, wherein a multidimensional force sensor is arranged in the finger part shell, the multidimensional force sensor comprises a plurality of gratings, a first cantilever beam, a second cantilever beam and a third cantilever beam, the first cantilever beam, the second cantilever beam and the third cantilever beam are used for generating deformation along with the external acting force of the finger part shell, the first cantilever beam and the second cantilever beam are arranged in the same plane, the third cantilever beam is vertical to the plane where the first cantilever beam and the second cantilever beam are arranged, the plurality of gratings are arranged on the surfaces of the first cantilever beam, the second cantilever beam and the third cantilever beam, and the plurality of gratings are connected with an optical detection system for measuring multidimensional force. The invention has cantilever beams and gratings distributed on the cantilever beams in the directions of X, Y and Z axis, and calculates the magnitude and direction of multidimensional force applied to the finger parts by applying force to the finger parts shells and utilizing the phenomenon that the central wavelength of reflected light applied by the gratings is changed.
Description
Technical Field
The invention relates to the field of multi-dimensional force measurement of optical sensors, in particular to a robot finger multi-dimensional force sensing device and method based on fiber bragg gratings.
Background
Sensors are a key part of robot control and feedback research. The force sensor is widely applied to the field of robots as a key sensor, and in mechanical sensing and feedback analysis of wrist, arm, finger and other structures of the robots, multi-dimensional stress change conditions between the structures and contact with the external environment are often required to be measured, and the action characteristics of the environmental force are sensed. The traditional dynamometer cannot meet the actual operation requirement, so that the design and research of a multi-dimensional sensor are developed, and some achievements are achieved in the aspects of sensor structure and performance.
The research of multi-dimensional force sensors has been in the past 20 th century and 70 s for over half a century of research history. There are resistance strain gauge sensors, capacitance sensors, optical sensors, etc. according to the sensing principle. At present, the resistance strain gauge type multi-dimensional force sensor has the characteristics of early development, wide application, high precision and high sensitivity.
However, the conventional strain gauge type sensor needs to be adhered with more strain gauges, has poor interference resistance and cannot be normally used in a severe environment. With the development of fiber grating sensing technology, fiber gratings are widely used in various sensing fields. Compared with the traditional sensor, the fiber grating sensor has the advantages of electromagnetic interference resistance, strong corrosion resistance, high temperature resistance, no temperature zero drift of wavelength values, capability of connecting a plurality of gratings with different central wavelengths in series on the same optical fiber, great reduction in the number of signal leads of the sensor, capability of working in a complex environment and the like.
A double-cross multi-dimensional force sensor structure is disclosed in a document with the name of 201911130106.2, namely 'a double-cross beam type three-dimensional force sensor based on fiber bragg grating', and the arrangement of the double-cross beam structure causes the sensor to be large in size and inconvenient to integrate at the position of a finger part of a robot.
Disclosure of Invention
The invention provides a multidimensional force sensing device and a multidimensional force sensing method for a robot finger part based on fiber bragg gratings, aiming at solving the problem that the multidimensional force sensing sensor for the robot finger part is inconvenient to use, wherein a cantilever beam and a grating arranged on the cantilever beam are arranged in the directions of X, Y and Z axis, the multidimensional force applied to the finger part shell is calculated by applying force to the finger part shell, and the magnitude and the direction of the multidimensional force applied to the finger part shell are calculated by utilizing the phenomenon that the central wavelength of reflected light of the grating is changed due to the stress.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a robot finger part multidimensional force sensing device based on fiber bragg gratings comprises a finger part shell, wherein a multidimensional force sensor is arranged in the finger part shell, the multidimensional force sensor comprises a plurality of gratings, a first cantilever beam, a second cantilever beam and a third cantilever beam, the first cantilever beam, the second cantilever beam and the third cantilever beam are used for generating deformation along with the external acting force of the finger part shell, the first cantilever beam and the second cantilever beam are arranged in the same plane, the third cantilever beam is perpendicular to the plane where the first cantilever beam and the second cantilever beam are arranged, the plurality of gratings are arranged on the surfaces of the first cantilever beam, the second cantilever beam and the third cantilever beam, and the first cantilever beam is matched with the gratings to sense the stress of an X axis;
the second cantilever beam is matched with the grating and used for sensing the stress of the Y axis;
the third cantilever beam is matched with the grating and used for sensing the stress of the Z axis;
an optical detection system for measuring multi-dimensional forces is connected to a plurality of the gratings.
Further, first cantilever beam and second cantilever beam are isometric rhombus plate body, and the axis mutually perpendicular of first cantilever beam and second cantilever beam, first cantilever beam include isometric A portion and B portion, and the second cantilever beam includes isometric C portion and D portion, A portion, B portion and C portion, D portion are provided with the go-between, the interior anchor ring lower part of go-between and the point position circular arc transitional coupling of A portion, B portion and C portion, D portion, the fixed grating that is provided with of up end of A portion, B portion and C portion, D portion, it is a plurality of the grating distributes along the axis of A portion, B portion and C portion, D portion respectively, mutually perpendicular between the grating, first cantilever beam and second cantilever beam and go-between structure as an organic whole.
Further, be the cross plate body after first cantilever beam and the combination of second cantilever beam, cross plate body bottom surface middle part is provided with the stay tube, the stay tube is ring tubular structure, stay tube and first cantilever beam and second cantilever beam structure as an organic whole, terminal surface fixedly connected with base under the stay tube, the base is discoid structure.
Further, the third cantilever beam includes bow-shaped portion, connecting portion and contact site, bow-shaped portion is the bow-shaped plate body that the elasticity material was made, and bow-shaped portion one end sets up connecting portion, the other end sets up the contact site, connecting portion and bow-shaped portion structure as an organic whole are provided with the grating along bow-shaped portion axis, connecting portion are cylindric structure, and connecting portion and bow-shaped portion set up in the support tube inside, the bottom surface of connecting portion and the up end contact of base, the contact site is hemispherical structure, and the contact site sets up in the stay tube outside.
Furthermore, the finger part shell comprises a hemispherical shell and a disc-shaped pressing ring arranged at the bottom of the shell, the shell and the pressing ring are of an integrated structure, and the bottom surface of the pressing ring is in contact with the top surface of the contact part;
cylindric inner groovy has been seted up on the interior anchor ring of go-between upper portion, the clamping ring sets up in inner groovy clearance position, and the up end of clamping ring is laminated with the up end of inner groovy, and the clearance is left to terminal surface and the inner groovy under terminal surface down, casing and go-between swing joint.
Further, optical detection system includes light source adjusting module, coupler, conversion module, DSP unit, main control unit and host computer, light source adjusting module output optical signal transmits a plurality of gratings respectively through the coupler, and a plurality of gratings output optical signal carries out photoelectric conversion through conversion module, and conversion module connects the DSP unit, and conversion module output electrical signal handles transmission to the main control unit through the DSP unit, the main control unit includes the MCU chip, the main control unit passes through the RS232 serial ports and connects the host computer, and the main control unit conveys detection signal to the host computer through the RS232 serial ports.
A method for calculating multidimensional force based on a fiber grating-based robot finger multidimensional force sensing device comprises the following steps:
step 1: the light source adjusting module outputs an optical signal to the grating, reflected light is output after the optical signal is reflected by the grating, and the central wavelength of the reflected light is lambdaB；
When external stress acts on the grating, the grating deforms, so that the central wavelength of reflected light deviates, wherein the central wavelength of the reflected light is related to the grating period and the effective refractive index of the grating, the grating generates an elasto-optical effect, the effective refractive index of the grating changes at the moment, and the central wavelength of the reflected light is in a linear relation with the stress borne by the grating, so that the deviation amount delta lambda of the central wavelength of the reflected light is utilizedBCalculating the axis strain delta at the reference point, and if so;
wherein P iseIs the elasto-optic coefficient;
therefore, the method comprises the following steps:
step 2: the third cantilever beam atress pushes down, and bow-shaped portion is the bow-shaped plate body that the elastic material made, and can know by elastomechanics and material mechanics, when outside axial load is F, it is as to appear its meeting an emergency:
wherein: i is sectionA face moment of inertia; e is the modulus of elasticity; n is the number of notches of the arch; l is1Is the bow short beam length; l is2Is the length of the long beam of the arch part; l is the length of the arcuate portion; the relationship between the wavelength drift amount and the axial load obtained from equations (1.2) and (2.1) is:
and step 3: influenced by Z axle stress, the clamping ring shifts down, and first cantilever beam and second cantilever atress are known by material mechanics, and when external axial load was F, its meeting an emergency can be expressed as:
the stress versus wavelength relationship can be obtained from equations (1.2) and (3.1):
wherein F is the stress of the free end of the beam, b and h are the width and thickness of the beam, E is the Young modulus of the beam, and l is the length of the beam;
and 4, step 4: after the stresses of the first cantilever beam, the second cantilever beam and the third cantilever beam are respectively calculated, the horizontal stress condition of the shell of the finger part of the robot is further calculated;
let the finger shell be subjected to horizontal force F (Z-axis force) and have component forces on X-axis and Y-axis as FX (X-axis force) FY (Y-axis force);
meanwhile, if the included angle between F and the X axis is theta, the relationship between F and FX and FY is:
and further the magnitude and direction of the finger stress are obtained.
Through the technical scheme, the invention has the beneficial effects that:
1. the invention is provided with a first cantilever beam, a second cantilever beam and a third cantilever beam which are deformed along with the external acting force of a finger part shell, wherein the first cantilever beam and the second cantilever beam are arranged in the same plane, the third cantilever beam is vertical to the plane where the first cantilever beam and the second cantilever beam are arranged, a plurality of gratings are arranged on the surfaces of the first cantilever beam, the second cantilever beam and the third cantilever beam, and the first cantilever beam is matched with the gratings to sense the stress of an X axis; the second cantilever beam is matched with the grating and used for sensing the stress of the Y axis; the third cantilever beam is matched with the grating and used for sensing the stress of the Z axis; an optical detection system for measuring multi-dimensional forces is connected to a plurality of the gratings.
When the outer shell of the finger part of the robot is under the action of an external force, the outer shell of the finger part can slide downwards due to component force acting on the Z axis, so that the third cantilever beam deforms, the central wavelength of reflected light changes after the grating arranged on the surface of the third cantilever beam is under the action of stress by utilizing the phenomenon that the central wavelength of the reflected light changes due to the stress of the grating, and finally wavelength information is demodulated through an optical detection system. Meanwhile, the component force acting on the X, Y axis can deform the first cantilever beam and the second cantilever beam, and similarly, the central wavelength generated by the gratings on the first cantilever beam and the second cantilever beam is also shifted. Through processing and calculation, the stress size and direction are determined, the multi-dimensional force sensor is integrated on the finger part of the robot, and the effect of accurately and effectively completing multi-dimensional force detection is achieved.
2. The invention adopts the grating as a transmission medium, transmits information by optical signals, is free from electromagnetic interference, has small volume, light structure, simple measurement principle, good stability, strong anti-interference capability and long service life, and can work in severe environments such as acid, alkali, salt and the like.
Drawings
Fig. 1 is a schematic structural diagram of a fiber grating-based robot finger multi-dimensional force sensing device and method.
Fig. 2 is a schematic structural diagram of a fiber grating-based robot finger multi-dimensional force sensing device and method.
Fig. 3 is a third structural schematic diagram of a fiber grating-based robot finger multi-dimensional force sensing device and method.
Fig. 4 is a fourth schematic structural diagram of a fiber grating-based robot finger multi-dimensional force sensing device and method.
Fig. 5 is a fifth structural diagram of a fiber grating-based robot finger multi-dimensional force sensing device and method.
Fig. 6 is a third cantilever force analysis diagram of a fiber grating-based robot finger multi-dimensional force sensing device and method.
FIG. 7 is a graph of force analysis of the first cantilever or the second cantilever of a fiber grating-based multi-dimensional force sensing device and method for a robot finger.
Fig. 8 is an electrical schematic diagram of an optical detection system of a fiber grating-based robot finger multi-dimensional force sensing device and method.
The reference numbers in the drawings are as follows: 1 is first cantilever beam, 2 is the second cantilever beam, 3 is the third cantilever beam, 4 is the grating, 5 is the go-between, 6 is finger's casing, 7 is the base, 8 is the stay tube, 9 is light source adjusting module, 10 is conversion module, 11 is the main control unit, 12 is the host computer, 301 is bow-shaped portion, 302 is connecting portion, 303 is the contact site, 601 is the shell, 602 is the clamping ring.
Detailed Description
The invention is further described with reference to the following figures and detailed description:
the second cantilever beam 2 is matched with the grating 4 to sense the stress of the Y axis;
the third cantilever beam 3 is matched with the grating 4 to sense the stress of the Z axis;
an optical detection system for measuring multi-dimensional forces is connected to the plurality of gratings 4.
In order to improve the grating 4 sensitivity and follow 5 centre of a circle arrays of go-between with grating 4, as shown in fig. 3, first cantilever beam 1 and second cantilever beam 2 are isometric rhombus plate body, and the axis mutually perpendicular of first cantilever beam 1 and second cantilever beam 2, first cantilever beam 1 includes isometric A portion and B portion, and second cantilever beam 2 includes isometric C portion and D portion, A portion, B portion and C portion, D portion are provided with go-between 5, the interior anchor ring lower part of go-between 5 and A portion, B portion and C portion, the point position circular arc transitional coupling of D portion, the fixed grating 4 that is provided with of up end of A portion, B portion and C portion, D portion, it is a plurality of the grating 4 distributes along the axis of A portion, B portion and C portion, D portion respectively, mutually perpendicular between the grating 4, first cantilever beam 1 and second cantilever beam 2 and go-between 5 are the integral structure.
For further optimizing product structure, be the cross plate body after first cantilever beam 1 and the combination of second cantilever beam 2, cross plate body bottom surface middle part is provided with stay tube 8, stay tube 8 is ring tubular structure, and stay tube 8 and first cantilever beam 1 and second cantilever beam 2 are the integral structure, terminal surface fixedly connected with base 7 under the stay tube 8, base 7 is discoid structure.
For making bow-shaped portion 301 receive stress deformation, third cantilever beam 3 includes bow-shaped portion 301, connecting portion 302 and contact site 303, bow-shaped portion 301 is the bow-shaped plate body that elastic material made, and bow-shaped portion 301 one end sets up connecting portion 302, the other end sets up contact site 303, connecting portion 302 and bow-shaped portion 301 structure as an organic whole are provided with grating 4 along bow-shaped portion 301 axis, connecting portion 302 is cylindric structure, and connecting portion 302 and bow-shaped portion 301 set up in inside the stay tube 8, the bottom surface of connecting portion 302 and the up end contact of base 7, contact site 303 is hemispherical structure, and contact site 303 sets up in the outside of stay tube 8.
In order to reflect the linkage of the finger part shell 6 with the component force of the X axis and the Y axis after being stressed, the finger part shell 6 comprises a hemispherical shell 601 and a disc-shaped pressure ring 602 arranged at the bottom of the shell 601, the shell 601 and the pressure ring 602 are of an integrated structure, and the bottom surface of the pressure ring 602 is in contact with the top surface of the contact part 303;
cylindric inner groovy has been seted up on go-between 5's interior anchor ring upper portion, clamping ring 602 sets up in inner groovy clearance position, and the clearance is left with inner groovy lower terminal surface to the up end laminating of clamping ring 602 and inner groovy, lower terminal surface, casing 6 and go-between 5 swing joint.
For facilitating the optical signal analysis of the grating 4, the optical detection system comprises a light source adjusting module 9, a coupler, a conversion module 10, a DSP unit, a main control unit 11 and an upper computer 12, the light source adjusting module 9 outputs optical signals to transmit a plurality of gratings 4 through the coupler respectively, the optical signals output by the gratings 4 are subjected to photoelectric conversion through the conversion module 10, the conversion module 10 is connected with the DSP unit, the electric signals output by the conversion module 10 are processed and transmitted to the main control unit 11 through the DSP unit, the main control unit 11 comprises a MCU chip, the main control unit 11 is connected with the upper computer 12 through an RS232 serial port, and the main control unit 11 transmits detection signals to the upper computer 12 through the RS232 serial port.
In this embodiment, as shown in fig. 3, 6 and 8, the light source adjusting module 9 is configured to emit a light source, the coupler is a 3dB coupler, the grating 4 is specifically a fiber Bragg grating, the number of the gratings 4 is 5, the gratings are respectively disposed on the part a and the part B of the first cantilever 1, the part C and the part D of the second cantilever 2, and the third cantilever, the five gratings 4 are connected in series, the numbers marked in the figures are FBG1, FBG3, FBG2, FBG4, and FBG5, the converting module 10 includes a photoelectric converter, an operational amplifier, an I-V converter, and an a/D converter, the converting module 10 converts the light signal reflected by the grating 4 into a digital signal carrying wavelength information, and the MUC chip is specifically a single chip;
light source adjusting module 9 is connected with the MUC chip through the UART serial port, the MUC chip controls the output of light source adjusting module 9, adjusting module 9 outputs optical signal to grating 4 through the 3dB coupler, grating 4 outputs reflected light to conversion module 10, conversion module 10 sends the digital signal carrying wavelength information into the singlechip after being processed by the DSP unit, the DSP unit communicates with the MUC chip through the ADC serial port, synchronous signal through light source adjusting module 9 and reflected light signal processed by the DSP unit, the MUC chip obtains the reflection center wavelength of grating 4 through relevant operation and transmits the data to host computer 12.
Example 2: 3-7, a method for calculating multidimensional force based on a fiber grating based multi-dimensional force sensing device for a robot finger, comprising the steps of:
firstly, when no acting force is applied to the outside of the finger part shell 6, the contact part 303 is contacted with the bottom surface of the pressing ring 602, the upward supporting force of the contact part 303 and the gravity of the shell 6 are in a stress balance state, and at the moment, the upper end surface of the pressing ring 602 is attached to the upper end surface of the inner groove of the connecting ring 5;
step 1: the light source adjusting module 9 outputs an optical signal to the grating 4, and outputs reflected light after being reflected by the grating 4, wherein the central wavelength of the reflected light is lambdaB；
When external stress acts on the grating 4, the grating 4 deforms, so that the central wavelength of reflected light shifts, wherein the central wavelength of the reflected light is related to the period of the grating 4 and the effective refractive index of the grating 4, the grating 4 generates an elasto-optic effect, the effective refractive index of the grating 4 changes at the moment, and the central wavelength of the reflected light is in a linear relation with the stress borne by the grating 4, so that the shift amount delta lambda of the central wavelength of the reflected light is utilized to realize the effect that the central wavelength of the reflected light is linearly shiftedBCalculating the axis strain delta at the reference point, and if so;
wherein P iseIs the elasto-optic coefficient;
therefore, the method comprises the following steps:
then when stress exists outside the finger part shell 6, the press ring 602 moves downwards along with the shell 601 under stress, and the contact part 303 is stressed to enable the arch part 301 to be stressed and deformed;
step 2: the third cantilever beam 3 is pressed downwards by force, the arch part 301 is an arch sheet made of stainless steel, and as can be seen from elasticity mechanics and material mechanics, when the external axial load is F, the strain is:
wherein: as shown in fig. 6, I is the section moment of inertia; e is the modulus of elasticity; n is the number of cuts of the arcuate portion 301; l is1Is the bow 301 short beam length; l is2Is the length of the long beam of arcuate 303; l is the length of the arcuate portion 301; the relationship between the wavelength drift amount and the axial load obtained from equations (1.2) and (2.1) is:
further, when the finger housing 6 is subjected to any external force, the finger housing 6 is moved downward by a longitudinal component force and the arcuate portion 301 is deformed by the force, and the first cantilever beam 1 and the second cantilever beam 2 on the connection ring 5 are strained by a transverse component force.
And step 3: under the influence of the Z-axis stress, the press ring 601 moves downwards, the first cantilever beam 1 and the second cantilever beam 2 are stressed, and as can be known from material mechanics, when the external axial load is F, the strain can be expressed as:
the stress versus wavelength relationship can be obtained from equations (1.2) and (3.1):
taking the part B of the first cantilever beam 1 as an example, as shown in FIG. 7, F is the stress applied to the free end of the beam, B and h are the width and thickness of the beam, E is the Young's modulus of the beam, and l is the length of the beam;
and 4, step 4: after the stresses of the first cantilever beam 1, the second cantilever beam 2 and the third cantilever beam 3 are respectively calculated, the horizontal stress condition of the robot finger shell 6 is further calculated;
let the finger case 6 receive horizontal force F (Z-axis force) and its component forces on X-axis and Y-axis are FX (X-axis force) FY (Y-axis force), respectively;
meanwhile, if the included angle between F and the X axis is theta, the relationship between F and FX and FY is:
and further the magnitude and direction of the finger stress are obtained.
The above-described embodiments are merely preferred embodiments of the present invention, and not intended to limit the scope of the invention, so that equivalent changes or modifications in the structure, features and principles described in the present invention should be included in the claims of the present invention.
Claims (7)
1. A robot finger multi-dimensional force sensing device based on fiber bragg grating comprises a finger shell (6), it is characterized in that a multi-dimensional force sensor is arranged in the finger part shell (6), the multi-dimensional force sensor comprises a plurality of gratings (4), a first cantilever beam (1), a second cantilever beam (2) and a third cantilever beam (3) which are used for generating deformation along with the external acting force of the finger part shell (6), the first cantilever beam (1) and the second cantilever beam (2) are arranged in the same plane, the third cantilever beam (3) is vertical to the plane where the first cantilever beam (1) and the second cantilever beam (2) are located, the plurality of gratings (4) are arranged on the surfaces of the first cantilever beam (1), the second cantilever beam (2) and the third cantilever beam (3), and the first cantilever beam (1) and the gratings (4) are matched for sensing X-axis stress;
the second cantilever beam (2) is matched with the grating (4) to sense the stress of the Y axis;
the third cantilever beam (3) is matched with the grating (4) to sense the stress of the Z axis;
an optical detection system for measuring multi-dimensional forces is connected to the plurality of gratings (4).
2. The fiber grating-based robot finger multidimensional force sensing device is characterized in that the first cantilever beam (1) and the second cantilever beam (2) are rhombic plate bodies with equal length, the central axes of the first cantilever beam (1) and the second cantilever beam (2) are perpendicular to each other, the first cantilever beam (1) comprises a part A and a part B which are equal in length, the second cantilever beam (2) comprises a part C and a part D which are equal in length, the part A, the part B, the part C and the part D are provided with connecting rings (5), the lower part of the inner annular surface of each connecting ring (5) is in arc transition connection with the tip positions of the part A, the part B, the part C and the part D, the upper end surfaces of the part A, the part B, the part C and the part D are fixedly provided with gratings (4), the gratings (4) are respectively distributed along the axes of the part A, the part B, the part C and the part D, and are perpendicular to each other, the first cantilever beam (1), the second cantilever beam (2) and the connecting ring (5) are of an integrated structure.
3. The fiber grating-based robot finger multidimensional force sensing device according to claim 2, wherein the first cantilever beam (1) and the second cantilever beam (2) are combined to form a cross-shaped plate, a support tube (8) is disposed in the middle of the bottom surface of the cross-shaped plate, the support tube (8) is a circular tubular structure, the support tube (8) is an integral structure with the first cantilever beam (1) and the second cantilever beam (2), a base (7) is fixedly connected to the lower end surface of the support tube (8), and the base (7) is a disc-shaped structure.
4. The fiber grating-based multi-dimensional force sensing device for a robot finger according to claim 3, characterized in that the third cantilever beam (3) comprises an arch part (301), a connecting part (302) and a contact part (303), the arch part (301) is an arch plate body made of elastic materials, one end of the arch part (301) is provided with a connecting part (302), the other end is provided with a contact part (303), the contact part (303), the connecting part (302) and the arch part (301) are of an integrated structure, a grating (4) is arranged along the axis of the arch part (301), the connecting part (302) is of a cylindrical structure, the connecting part (302) and the arch part (301) are arranged in the supporting tube (8), the bottom surface of the connecting part (302) is contacted with the upper end surface of the base (7), the contact part (303) is of a hemispherical structure, and the contact part (303) is arranged outside the supporting pipe (8).
5. The fiber bragg grating-based robot finger multi-dimensional force sensing device is characterized in that the finger shell (6) comprises a hemispherical shell (601) and a disc-shaped press ring (602) arranged at the bottom of the shell (601), the shell (601) and the press ring (602) are of an integrated structure, and the bottom surface of the press ring (602) is in contact with the top surface of the contact part (303);
cylindric inner groovy has been seted up on the interior anchor ring upper portion of go-between (5), clamping ring (602) set up in inner groovy clearance position, and the clearance is left with inner groovy lower terminal surface to the up end laminating of clamping ring (602) and the up end laminating of inner groovy, lower terminal surface, casing (6) and go-between (5) swing joint.
6. The fiber grating-based multi-dimensional force sensing device for a robot finger of claim 1, characterized in that the optical detection system comprises a light source adjusting module (9), a coupler, a conversion module (10), a DSP unit, a main control unit (11) and an upper computer (12), the light source adjusting module (9) outputs optical signals which are respectively transmitted to the plurality of gratings (4) through the coupler, the optical signals output by the plurality of gratings (4) are subjected to photoelectric conversion through the conversion module (10), the conversion module (10) is connected with the DSP unit, the electric signals output by the conversion module (10) are processed by the DSP unit and transmitted to the main control unit (11), the main control unit (11) comprises an MCU chip, the main control unit (11) is connected with the upper computer (12) through an RS232 serial port, and the main control unit (11) transmits a detection signal to the upper computer (12) through the RS232 serial port.
7. A method for calculating multidimensional force of a robot finger part based on a fiber grating and the multidimensional force sensing device and method based on any one of claims 1 to 6 is characterized by comprising the following steps:
step 1: the light source adjusting module (9) outputs an optical signal to the grating (4), and reflected light is output after being reflected by the grating (4), wherein the central wavelength of the reflected light is lambdaB；
When external stress acts on the grating (4), the grating (4) deforms, so that the central wavelength of reflected light shifts, wherein the central wavelength of the reflected light is related to the period of the grating (4) and the effective refractive index of the grating (4), the grating (4) generates an elasto-optical effect, the effective refractive index of the grating (4) changes at the moment, the central wavelength of the reflected light is in a linear relation with the stress borne by the grating (4), and therefore the shift amount delta lambda of the central wavelength of the reflected light is usedBCalculating the axis strain delta at the reference point;
wherein P iseIs the elasto-optic coefficient;
therefore, the method comprises the following steps:
step 2: the third cantilever beam (3) is forced to press down, and bow-shaped portion (301) is the bow-shaped plate body that the elastic material was made, and known by elastomechanics and material mechanics, when external axial load was F, it is as follows to appear its strain:
wherein: i is a section moment of inertia; e is the modulus of elasticity; n is the number of notches of the arcuate portion (301); l is1Is the length of the short beam of the arch part (301); l is2Is the length of the long beam of the arch part (301); l is the length of the arcuate portion (301); the relationship between the wavelength drift amount and the axial load obtained from equations (1.2) and (2.1) is:
and step 3: under the influence of Z-axis stress, the pressure ring (602) moves downwards, the first cantilever beam (1) and the second cantilever beam (2) are stressed, and the strain can be expressed as follows according to the mechanics of materials when the external axial load is F:
the stress versus wavelength relationship can be obtained from equations (1.2) and (3.1):
wherein F is the stress of the free end of the beam, b and h are the width and thickness of the beam, E is the Young modulus of the beam, and l is the length of the beam;
and 4, step 4: after the stresses of the first cantilever beam (1), the second cantilever beam (2) and the third cantilever beam (3) are respectively calculated, the horizontal stress condition of the robot finger shell (6) is further calculated;
the component forces of the finger part shell (6) on the X axis and the Y axis when the horizontal force F (Z axis stress) is applied are FX (X axis stress) FY (Y axis stress) respectively;
meanwhile, if the included angle between F and the X axis is theta, the relationship between F and FX and FY is:
and further the magnitude and direction of the finger stress are obtained.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113188703A (en) * | 2021-04-24 | 2021-07-30 | 首都医科大学宣武医院 | Three-dimensional force sensor and measuring method |
| CN113607313A (en) * | 2021-07-09 | 2021-11-05 | 武汉理工大学 | Laminated fiber grating six-dimensional force-torque sensor based on C-shaped beam |
| CN114323410A (en) * | 2021-12-31 | 2022-04-12 | 长飞光纤光缆股份有限公司 | Spoke type fiber bragg grating pressure sensor |
| CN114858336A (en) * | 2022-05-17 | 2022-08-05 | 重庆交通大学 | Low-coupling fiber grating three-dimensional force sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113188703A (en) * | 2021-04-24 | 2021-07-30 | 首都医科大学宣武医院 | Three-dimensional force sensor and measuring method |
| CN113607313A (en) * | 2021-07-09 | 2021-11-05 | 武汉理工大学 | Laminated fiber grating six-dimensional force-torque sensor based on C-shaped beam |
| CN114323410A (en) * | 2021-12-31 | 2022-04-12 | 长飞光纤光缆股份有限公司 | Spoke type fiber bragg grating pressure sensor |
| CN114323410B (en) * | 2021-12-31 | 2023-06-06 | 长飞光纤光缆股份有限公司 | Spoke type fiber grating pressure sensor |
| CN114858336A (en) * | 2022-05-17 | 2022-08-05 | 重庆交通大学 | Low-coupling fiber grating three-dimensional force sensor |
| CN114858336B (en) * | 2022-05-17 | 2023-12-01 | 重庆交通大学 | Low-coupling fiber grating three-dimensional force sensor |
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