CN112213009B - Multi-axis force sensor based on optical principle - Google Patents
Multi-axis force sensor based on optical principle Download PDFInfo
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- CN112213009B CN112213009B CN202011193267.9A CN202011193267A CN112213009B CN 112213009 B CN112213009 B CN 112213009B CN 202011193267 A CN202011193267 A CN 202011193267A CN 112213009 B CN112213009 B CN 112213009B
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- 230000002093 peripheral effect Effects 0.000 claims abstract description 51
- 238000006073 displacement reaction Methods 0.000 claims abstract description 32
- 230000009471 action Effects 0.000 claims abstract description 11
- 239000000725 suspension Substances 0.000 claims description 21
- 238000007789 sealing Methods 0.000 claims description 8
- 230000008859 change Effects 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 7
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- HCWZEPKLWVAEOV-UHFFFAOYSA-N 2,2',5,5'-tetrachlorobiphenyl Chemical compound ClC1=CC=C(Cl)C(C=2C(=CC=C(Cl)C=2)Cl)=C1 HCWZEPKLWVAEOV-UHFFFAOYSA-N 0.000 description 3
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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
- G01L1/247—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 using distributed sensing elements, e.g. microcapsules
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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
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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
Abstract
The invention discloses an optical principle-based multi-axis force sensor, which comprises a sensing member and a cover member stacked on the upper side of the sensing member. The sensing piece is provided with a hollow peripheral part and a bearing part arranged in the center of the peripheral part, the bearing part and the peripheral part are connected with the peripheral part through a plurality of elastic beam hanging parts uniformly distributed on the outer peripheral side of the bearing part, and the bearing part deflects or moves relative to the peripheral part under the action of external force. A first displacement detector for detecting the amount of deflection or displacement of the bearing part relative to the peripheral part is arranged between the cover part and the bearing part. Therefore, the multi-axis force sensor is simple in structure and convenient to manufacture and produce.
Description
Technical Field
The invention relates to the technical field of multi-axis force sensors, in particular to a multi-axis force sensor based on an optical principle.
Background
A multi-axis force sensor is a device capable of measuring linear forces and moments in multiple degrees of freedom, up to 6 degrees of freedom, i.e., linear forces (Fx, Fy, and Fz) in the X, Y, and Z axes and moments (Mx, My, and Mz) each rotating about the X, Y, and Z axes.
At present, the structure of the existing multi-axis force sensor is generally complex, and the manufacturing difficulty is high. For example, publication No. CN110050179A discloses a multi-axis force sensor comprising a pair of superimposed ring-shaped sensor elements, the ring-shaped sensor unit being formed by an upper element and a lower element, which are connected together at points around their circumference by means of elastically mounted connecting rods, which may extend in the same plane as the rings. A displacement detection circuit is provided within the upper and lower elements, the displacement detection circuit being arranged to detect a displacement or movement of the upper and lower elements in an applied force of the applied example to be sensed. The sensing principle of the multi-axis force sensor is based on optical sensing which measures deflection displacements caused by external forces or moments, these deflections being used as inputs to a calibration matrix to estimate linear forces and moments in various directions.
Although the structure of the multi-axis force sensor is simplified, the structure is still relatively complex, and the manufacturing difficulty is high.
Disclosure of Invention
Aiming at the problems in the prior art, the invention mainly aims to provide a multi-axis force sensor based on an optical principle, and aims to solve the problems of complex structure and high manufacturing difficulty of the existing multi-axis force sensor.
In order to achieve the above object, the present invention provides an optical principle-based multi-axis force sensor, including a sensing member and a capping member stacked on an upper side of the sensing member;
the sensing piece is provided with a hollow peripheral part and a bearing part arranged in the center of the peripheral part, the bearing part and the peripheral part are connected with the peripheral part through a plurality of elastic beam hanging parts uniformly distributed on the outer peripheral side of the bearing part, and the bearing part deflects or moves relative to the peripheral part under the action of external force;
a first displacement detector for detecting the deflection amount or the displacement amount of the bearing part relative to the peripheral part is arranged between the cover part and the bearing part.
Optionally, the first displacement detector comprises:
the first reflector is arranged on one side of the cover piece facing the bearing part;
the first PCB is arranged on one side, facing the sealing cover part, of the bearing part, a plurality of upper optical sensors are arranged on the first PCB, and each upper optical light sensor is provided with an emitting part for emitting light and a receiving part for receiving the light reflected by the reflector.
Optionally, the first reflector includes a flat reflecting surface and two oblique reflecting surfaces rotationally symmetrically disposed at an outer edge of the flat reflecting surface, and the two oblique reflecting surfaces are disposed along an X axis;
the upper optical sensor comprises two first optical sensors arranged along the X-axis direction, two second optical sensors arranged along the Y-axis direction and two third optical sensors arranged opposite to the inclined reflecting surfaces;
one side of the oblique reflecting surface is close to the transmitting part of the third optical sensor, and the other side of the oblique reflecting surface is far away from the receiving part of the third optical sensor, so that the oblique reflecting surface is relatively inclined towards the transmitting part of the third optical sensor.
Optionally, a plurality of first elastic pieces uniformly distributed by taking the center of the first reflector as an original center are arranged between the first reflector and the cover component;
the first adjusting piece is arranged on the sealing cover piece and corresponds to the first elastic piece, the first adjusting piece sequentially penetrates through the sealing cover piece and the first elastic piece, and the head of the first adjusting piece is inserted on the first reflector; the first adjusting piece is rotated to compress or relax the first elastic piece so as to change the distance and/or deflection amount of the first reflecting mirror relative to the first PCB.
Optionally, the first elastic member is a spring, an O-ring, or a hollow rubber sleeve.
Optionally, the elastic suspension beam portions are arranged in pairs, and comprise a first suspension beam and a second suspension beam;
the first suspension beam and the second suspension beam are arranged in parallel; or the two ends are mutually overlapped to form a triangle, the merging end of the triangle is connected with the bearing part, and the other two ends are connected with the peripheral part.
Optionally, the multi-axis force sensor further comprises a fixture stacked below the sensing member;
one side of the sensing piece facing the fixing piece is provided with a plurality of cushion block parts which are uniformly distributed along the circumferential direction of the peripheral part of the sensing piece, the lower end of each cushion block part is provided with an elastic connecting part which can stretch or contract in the axial direction of each cushion block part, and the elastic connecting parts are connected to the fixing piece;
a second displacement detector for detecting the deflection amount or the movement amount of the bearing part relative to the fixed part is arranged between the fixed part and the bearing part.
Optionally, the second displacement detector comprises:
the second reflector is arranged on one side, facing the bearing part, of the fixing piece;
the bearing part faces the second PCB on one side of the fixing part, a plurality of lower optical sensors are arranged on the second PCB, and each lower optical sensor comprises two fourth optical sensors arranged along the X-axis direction and two fifth optical sensors arranged along the Y-axis direction.
Optionally, a plurality of second elastic members are uniformly distributed by taking the center of the second reflector as the origin center between the second reflector and the fixing member;
the fixed piece is provided with a second adjusting piece corresponding to the second elastic piece, the second adjusting piece sequentially penetrates through the fixed piece and the second elastic piece, and the head of the second adjusting piece is inserted on the second reflector; rotating the second adjusting member to compress or relax the second elastic member to change the distance and/or deflection amount of the second reflecting mirror relative to the second PCB.
Optionally, the upper optical sensor and the lower optical sensor are photodiodes, reflective sensors, or wavelength sensors.
The multi-axis force sensor provided by the invention measures force and moment by detecting the deformation amount of the internal structure of the sensor, and particularly comprises a sensing piece and a cover piece stacked on the upper side of the sensing piece, wherein the sensing piece is provided with a hollow peripheral part and a bearing part arranged in the center of the peripheral part, the bearing part and the peripheral part are connected with the peripheral part through a plurality of elastic suspension beam parts uniformly distributed on the peripheral side of the bearing part, and the bearing part deflects or moves relative to the peripheral part under the action of external force. A first displacement detector for detecting the amount of deflection or movement of the carrying part relative to the peripheral part is provided between the cover member and the carrying part. The deformation of the internal structure of the sensor is mainly provided by the elastic cantilever part which is arranged between the peripheral part of the sensing part and the bearing part along the radial direction of the sensing part, the structure is simple and compact, and the linear movement, the rotation, the front side, the back side, the left side and the right side of the sealing part in the axial direction of the bearing part can be effectively sensed.
And, can also set up the fixed part below the sensing part, and set up the cushion part between sensing part and fixed part, set up the elastic coupling part that can stretch or contract in the sensing part axial in the cushion part and one side that the fixed part connects, and set up the second displacement detector of deflection amount or displacement of detecting the bearing part relative to fixed part between fixed part and bearing part lower flank of the sensing part, this second displacement detector can detect the bearing part and move along axial linear motion and all around turn on one's side, combine the axial displacement of the bearing part and all around measurement all around of the first displacement detector detection, can calculate the bearing part and move all around in the bearing part plane, further realize the deformation amount of the sensor in the bearing part plane, thus calculate the force that causes these deformation amounts.
Drawings
FIG. 1 is an exploded view of an embodiment of the optical-based multi-axis force sensor of the present invention;
FIG. 2 is a schematic structural diagram of a sensing element in an embodiment of the optical-based multi-axis force sensor of the present invention;
FIG. 3 is a schematic diagram of the distribution of the elastic cantilever beam in an embodiment of the multi-axis force sensor based on optical principles of the present invention;
FIG. 4 is a schematic diagram of the structure of the reflective surface of the first reflector in an embodiment of the multi-axis force sensor based on optical principles of the present invention;
FIG. 5 is a schematic diagram of the distribution of optical sensors on a first PCB in an embodiment of the multi-axis force sensor based on optical principles of the present invention;
FIG. 6 is a schematic diagram of the reflection of light between a third optical sensor and a slanted reflective surface in an embodiment of the multi-axis force sensor based on optical principles of the present invention;
FIG. 7 is a schematic diagram of the position of a third optical sensor and a slanted reflective surface in an embodiment of the multi-axis force sensor based on optical principles of the present invention;
FIG. 8 is a schematic diagram of the distribution of optical sensors on a second PCB in an embodiment of the multi-axis force sensor based on optical principles of the present invention;
fig. 9 is a schematic diagram of the connection of the first mirror to the closure member in an embodiment of the optical-based multi-axis force sensor of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to the attached drawing 1, in the embodiment of the present invention, a multi-axis force sensor based on optical principle is provided to achieve the measurement of the forces/moments of 4 degrees of freedom Mx, My, Mz, and Fz. The optical principle-based multi-axis force sensor includes a sensing member 1 and a capping member 2 stacked on an upper side of the sensing member 1. The sensing member 1 has a hollow peripheral portion 1a and a bearing portion 1b disposed at the center of the peripheral portion 1a, and the bearing portion 1b and the peripheral portion 1a are connected to the peripheral portion 1a through a plurality of elastic beam suspension portions 1c uniformly distributed on the outer periphery of the bearing portion 1 b.
In the present embodiment, for convenience of understanding, a plane on which the sensing element 1 is located is defined as an XY plane, left and right sides of the sensing element 1 are disposed substantially along an X axis, front and rear sides of the sensing element 1 are disposed substantially along a Y axis, and a central axis of the sensing element 1 is disposed substantially along the Y axis. Still further defined are the linear forces Fx, Fy and Fz along the X, Y and Z axes and the moments Mx, My and Mz rotating about the X, Y and Z axes.
As shown in fig. 2, the bearing part 1b and the peripheral part 1a are connected by an elastic beam part 1c, so that the bearing part 1b can be tilted forwards, backwards, leftwards, rightwards, and leftwards, rotate in the XY plane, and move upwards and downwards in the Z-axis direction, and thus, three moments Mx, My, and Mz and deformation caused by the force Fz can be sensed, and any one or more of Mx, My, Mz, and Fz causing deformation can be reversely calculated, so that multi-axis force/moment sensing is realized.
Because the elastic cantilever beam part 1c greatly limits the translation trend of the bearing part 1b in the XY plane in all directions distributed on the XY plane, the bearing part 1b cannot form meaningful movement in the XY plane, and therefore, the sensing piece 1 can only realize four-axis sensing.
Accordingly, in order to detect the deformation of the bearing part 1b upon receiving the force/moment of any one or more of Mx, My, Mz, or Fz, a first displacement detector for detecting the amount of deflection or displacement of the bearing part 1b relative to the peripheral part 1a is provided between the cover member 2 and the bearing part 1 b.
The first displacement detector includes a first reflector 41 disposed on a side of the cover member 2 facing the bearing portion 1b and a first PCB 42 disposed on a side of the bearing portion 1b facing the cover member 2, the first PCB 42 being provided with a plurality of upper optical sensors, each of the upper optical sensors having an emitting portion for emitting light and a receiving portion for receiving light reflected by the reflector. The peripheral shape of the first reflector 41 may be circular, rectangular or other shapes, and only covers all the optical sensors on the first PCB 42.
Specifically, in order to realize different forces/moments, in the present embodiment, as shown in fig. 4, the first reflecting mirror 41 includes a flat reflecting surface 41a and two oblique reflecting surfaces 41b which are rotationally symmetrically disposed at the outer edge of the flat reflecting surface 41a, and the two oblique reflecting surfaces 41b are disposed along the X axis. As shown in fig. 5, the upper optical sensors include two first optical sensors 421 disposed along the X-axis direction, two second optical sensors 422 disposed along the Y-axis direction, and two third optical sensors 423 disposed opposite to the inclined reflective surfaces. The first optical sensor 421 and the second optical sensor 422 are disposed in parallel to the flat reflection portion, and the third optical sensor 423 is disposed opposite to the oblique reflection surface 41 b.
As shown in fig. 6, the oblique reflection surface 41b is inclined with respect to the emission portion 423a of the third optical sensor 423 such that one side thereof is close to the emission portion 423a of the third optical sensor 423 and the other side thereof is distant from the reception portion 423b of the third optical sensor 423. Thereby, the light emitted from the emitting portion 423a of the third optical sensor 423 can be reflected to the receiving portion 423b of the third optical sensor 423 by the oblique reflecting surface 41 b. More specifically, it is required that: as shown in fig. 7, the middle line of the interval between the transmitting portion 423a and the receiving portion 423b is collinear with the middle line of the oblique reflective surface 41b, the included angle between the connecting line between the midpoint of the transmitting portion 423a and the midpoint of the oblique reflective surface 41b and the middle line of the oblique reflective surface 41b is a positive value, and the included angle between the connecting line between the midpoint of the receiving portion 423b and the midpoint of the oblique reflective surface 41b and the middle line of the oblique reflective surface 41b is a negative value, so as to ensure that the light emitted by the transmitting portion 423a can be refracted by the oblique reflective surface 41b and received by the receiving portion 423 b.
In order to be understood that the present invention measures the deformation of the sensing element 1 of the multi-axis force sensor under different forces/moments and the working state of the optical sensor after deformation, the following description is made:
under the action of the moment Mx:
the bearing part 1b relatively generates a rotation (i.e., a front-back flip) around the X axis. At this time, the distance between the two second optical sensors 422 and the surface of the first reflector 41 changes, and if the bearing part 1b is turned over to the front side, the second optical sensor 422 at the rear side is close to the first reflector, so that the received light reflected by the first reflector 41 is stronger. And the second optical sensor 422 on the front side is far away from the first reflector so that it receives weaker light reflected by the first reflector 41. Thus, the light intensity received by the two second optical sensors 422 has a difference, and the amount of rotation of the carrying section 1b, and thus the back thrust moment Mx, can be calculated from this difference.
Since the two first optical sensors 421 and the two third optical sensors 423 are disposed along the X-axis, the two first optical sensors 421 are at the same distance from the first reflector 41, and the received light intensities reflected by the first reflector 41 are the same. Similarly, the intensities of the light beams reflected by the first reflecting mirror 41 and received by the two third optical sensors 423 are also consistent. That is, the two first optical sensors 421 and the two second optical sensors 422 do not generate signal changes. The measurement of the moment Mx is not disturbed.
Under the action of the moment My:
the bearing part 1b relatively generates a rotation (i.e., left-right turning) around the Y-axis. At this time, there is a difference in the light intensity received by the two first optical sensors 421, and the calculated moment My can be derived reversely from the difference.
Under the action of the moment Mz:
the bearing part 1b relatively generates a rotation around the Z-axis (i.e., rotation in the XY plane). At this time, since the first optical sensor 421 is opposite to the oblique reflective surface 41b of the first reflective mirror 41, the rotation of the bearing part 1b on the XY plane changes the distance between the middle line of the third optical sensor 423 and the middle line of the oblique reflective surface 41b, if the bearing part 1b rotates clockwise, the left third optical sensor 423 is close to the oblique reflective surface 41b, and the right third optical sensor 423 is far from the oblique reflective surface 41b, the light intensities received by the two sensors will generate a difference, and the moment Mz can be calculated reversely by the difference.
Under the action of force Fz:
the bearing part 1b relatively generates a position upward or downward along the Z-axis direction, the two first optical sensors 421, the two second optical sensors 422 and the two third optical sensors 423 are simultaneously close to or far away from the first reflector 41, the light intensity received by the first optical sensors is simultaneously increased or decreased, the difference value of each optical sensor can be obtained by comparing the light intensity currently received by each optical sensor with the light intensity received by the previous state, the average value or the sum of the difference values is calculated, and the thrust Fz is further reversely pushed.
The invention provides a multi-axis force sensor for measuring force and moment by detecting deformation amount of an internal structure of the sensor, specifically, the multi-axis force sensor comprises a sensing piece 1 and a cover piece 2 stacked on the upper side of the sensing piece 1, the sensing piece 1 is provided with a hollow peripheral part 1a and a bearing part 1b arranged at the central position of the peripheral part 1a, the bearing part 1b and the peripheral part 1a are connected with the peripheral part 1a through a plurality of elastic suspension beam parts 1c uniformly distributed on the outer peripheral side of the bearing part 1b, and the bearing part 1b deflects or moves relative to the peripheral part 1a under the action of external force. A first displacement detector that detects the amount of deflection or movement of the bearing portion 1b with respect to the outer peripheral portion 1a is provided between the lid member 2 and the bearing portion 1 b. The deformation of the internal structure of the sensor is mainly provided by an elastic cantilever part which is arranged between the peripheral part 1a and the bearing part 1b of the sensing piece 1 along the radial direction of the sensing piece 1, the structure is simple and compact, and the linear movement, the rotation, the front side, the back side, the left side and the right side of the sealing piece 2 in the axial direction of the bearing part 1b can be effectively sensed, so that the measurement of Mx, My, Mz and Fz can be realized.
In addition, since a certain alignment relationship needs to be maintained between the oblique reflecting surface 41b and the third optical sensor 423 so that the oblique reflecting surface 41b can reflect the light emitted from the third optical sensor 423, it is necessary to limit the translation of the bearing portion 1b in the XY plane. Therefore, in the present embodiment, the elastic suspended beam portions 1c are arranged in pairs, each pair of the elastic suspended beam portions 1c includes a first suspended beam and a second suspended beam, and the first suspended beam and the second suspended beam can be arranged in a parallel or non-parallel manner. For example, as shown in fig. 3(a), the first suspension beam and the second suspension beam can be arranged in parallel and uniformly distributed in the center of the bearing part 1b, so that the sensing element 1 forms a wheel-like structure, and the first suspension beam and the second suspension beam correspond to spokes and support the bearing part 1b in the center of the sensing element 1, thereby preventing the bearing part 1b from moving in the plane of the sensing element 1. As shown in fig. 3(c), the first suspension beam and the second suspension beam that are disposed in a non-parallel manner may be brought together at a certain angle to form a triangular shape, the merging end of which is connected to the bearing portion 1b, and the remaining two ends of which are connected to the peripheral portion 1 a. By the plurality of first suspension beams and the plurality of second suspension beams which are arranged in pairs, the lateral rigidity of the bearing part 1b can be increased to limit the bearing part 1b to move in the X axial direction and the Y axial direction, so that the inclined reflecting surface 41b and the third optical sensor 423 can ensure an aligned state, the rotation amount of the bearing part 1b in the XY plane can be calculated conveniently through the change of the light intensity, and the moment Mz which causes the bearing part 1b to rotate in the XY plane can be effectively calculated reversely.
Of course, in addition to the above-described arrangement of the elastic beam portions 1c in pairs, a single elastic beam portion 1c may be adopted, and specifically, as shown in fig. 3(b), the movement of the bearing portion 1b in the X-axis direction and the Y-axis direction can be restricted by providing a plurality of elastic beam portions 1c to support the bearing portion 1 b.
It should be noted that, according to the range of force/moment to be sensed, the number of the elastic suspension beam portions 1c can be increased or decreased, or the thickness, height and length of the elastic suspension beam portions 1c can be adjusted to adjust the elastic coefficient of each elastic suspension chain portion, and thus the deformation of the bearing portion 1b under the force/moment can be adjusted.
Optionally, in this embodiment, a plurality of first elastic members 21 uniformly distributed with the center of the first reflector 41 as the origin are disposed between the first reflector 41 and the cover 2. By providing a plurality of first elastic members 21, the position of the first reflecting mirror 41 relative to the first PCB can be adjusted by compressing the first elastic members 21 at different positions, thereby adjusting the position of the first reflecting mirror 41 relative to the upper optical sensor, and facilitating the precise assembly and initial signal adjustment of the multi-axis force sensor. And the uniformly distributed first elastic members 21 can also provide uniform pressure to maintain flatness of the mirror surface while reducing vibration.
Specifically, as shown in fig. 9, a first adjusting member 22 corresponding to the first elastic member 21 is provided on the cover member 2, the first adjusting member 22 passes through the cover member 2 and the first elastic member 21 in sequence, and the head portion thereof is inserted into the first reflector 41. The first elastic member 21 can be compressed or released by rotating the first adjustment member 22 to change the distance and/or deflection amount of the first reflecting mirror 41 with respect to the first PCB board 42, thereby adjusting the position of the first reflecting mirror 41 with respect to each of the upper optical sensors.
Alternatively, the first elastic member 21 is a structural member having elasticity, such as a spring, an O-ring, or a hollow rubber sleeve.
Example 2
On the basis of the above embodiment 1, as shown in fig. 1-2, a fixing member 3 is stacked below the sensing member 1. A plurality of pad blocks 1d are uniformly distributed along the circumferential direction of the peripheral portion 1a of the sensing member 1 on the side of the sensing member 1 facing the fixing member 3, the lower end of each pad block 1d is provided with an elastic connection portion 1f capable of stretching or contracting in the axial direction of the pad block 1d, and the elastic connection portion 1f is connected to the fixing member 3. A second displacement detector that detects the amount of deflection or movement of the bearing portion 1b with respect to the fixing member 3 is provided between the fixing member 3 and the bearing portion 1 b.
The second displacement detector includes: a second reflector 51 disposed on the side of the fixing member 3 facing the carrying part 1b, and a second PCB 52 disposed on the side of the carrying part 1b facing the fixing member 3. As shown in fig. 8, a plurality of lower optical sensors are disposed on the second PCB 52, and the lower optical sensors include two fourth optical sensors 521 disposed along the X-axis direction and two fifth optical sensors 522 disposed along the Y-axis direction.
In particular, in this embodiment, the elastic connection is provided by two support arms crossing in an X-shape, which can be compressed or stretched.
Because the elastic connection portion 1f can be stretched or contracted in the axial direction of the sensing element 1, when the lower portion of the sensing element 1 (i.e., the pad portion 1d and the elastic connection portion 1 f) can also realize roll turning in front, back, left and right and axial movement of the sensing element 1, that is, under the action of the moments Mx, My and Fz, the lower portion of the sensing element 1 will also deform to some extent, so that the distances between the fourth optical sensor 521 and the fifth optical sensor 522 on the lower side of the bearing portion 1b and the second reflector on the fixing member 3 are changed, and the fourth optical sensor 521 and the fifth optical sensor 522 are used for detecting the corresponding deformation, and the specific detection principle is calculated by the difference of the light intensity received by the two fourth optical sensors 521 and the two fifth optical sensors 522.
Since the upper portion of the sensing member 1 (i.e., the supporting portion 1b and the peripheral portion 1 a) and the lower portion of the sensing member 1 are disposed along the Z-axis, there is a height difference H between the upper portion and the lower portion along the Z-axis, which results in a moment difference M Δ x between the moment Mx1 measured based on the difference between the light intensities of the two first optical sensors 421 and the moment Mx2 measured based on the difference between the light intensities of the two fourth optical sensors 521. The moment Mx is essentially the product of a moment arm along the Z-axis and a force component parallel to the Y-axis, which can be equivalent to the force Fy exerted by the multi-axis force sensor in the Y-axis direction. Assuming that the point of action of Fy is at a distance L1 from the carrier part 1b of the sensor 1, the distance to the elastic connection 1f is (L1 + H), Mx1= Fy × L1, Mx2= Fy × L + H, max = Mx2-Mx1= Fy × L + H) -Fy L1= Fy × H. While the height H is an already designed quantity, so it is possible to achieve a measurement of the linear force of the multi-axis force sensor in the Y-axis direction by calculating the force Fy in combination with amax and H.
Similarly, the force Fx can also be obtained by calculating the force Fx based on the moment My1 measured by the two second optical sensors 422 and the moment difference M Δ y of the moment My2 measured by the two fifth optical sensors 522, so as to measure the linear force of the multi-axis force sensor in the X axis direction.
In the present embodiment, by providing the fixing member 3 below the sensing member 1, and providing the pad portion 1d between the sensing member 1 and the fixing member 3, an elastic connection portion 1f capable of stretching or contracting in the axial direction of the sensing member 1 is provided on the side where the pad portion 1d is connected to the fixing member 3, and a second displacement detector for detecting the deflection amount or the displacement amount of the bearing part 1b relative to the fixed part 3 is arranged between the fixed part 3 and the lower side surface of the bearing part 1b of the sensing member 1, the second displacement detector can detect the linear movement of the bearing part 1b along the axial direction and the side turning in the front, back, left and right directions, and can calculate the front, back, left and right movements of the bearing part 1b in the plane of the bearing part 1b by combining the axial displacement of the bearing part 1b detected by the first displacement detector and the measurement in the front, back, left and right directions, so that the deformation of the sensor in the plane of the bearing part 1b is further realized, and the force causing the deformation is calculated.
Thereby, a measurement of the force/moment of the sensor in 6 degrees of freedom is enabled.
Optionally, in this embodiment, a plurality of second elastic members are uniformly distributed between the second reflector 51 and the fixing member 3 with the center of the second reflector 51 as the origin. And, the fixed part 3 is provided with a second adjusting part corresponding to the second elastic part, the second adjusting part passes through the fixed part 3 and the second elastic part in sequence, and the head part of the second adjusting part is inserted on the second reflector 51. The second adjustment member is rotated to compress or relax the second elastic member to change the distance and/or deflection amount of the second reflecting mirror 51 with respect to the second PCB 52. Thereby, the position of the second reflecting mirror 51 can be adjusted.
Optionally, in this embodiment, the upper optical sensor and the lower optical sensor are photodiodes, reflective sensors, or wavelength sensors.
The above description is only a preferred embodiment of the present invention and should not be taken as limiting the invention, and any minor modifications, equivalents and improvements made to the above embodiment according to the technical spirit of the present invention should be included in the protection scope of the technical solution of the present invention.
Claims (8)
1. An optical principle-based multi-axis force sensor, comprising a sensing member and a capping member stacked on an upper side of the sensing member;
the sensing piece is provided with a hollow peripheral part and a bearing part arranged in the center of the peripheral part, the bearing part and the peripheral part are connected with the peripheral part through a plurality of elastic beam hanging parts uniformly distributed on the outer peripheral side of the bearing part, and the bearing part deflects or moves relative to the peripheral part under the action of external force;
a first displacement detector for detecting the deflection amount or the movement amount of the bearing part relative to the peripheral part is arranged between the cover part and the bearing part;
the first displacement detector includes:
the first reflector is arranged on one side of the cover piece facing the bearing part;
the first PCB is arranged on one side of the bearing part facing the sealing cover part, a plurality of upper optical sensors are arranged on the first PCB, and each upper optical sensor is provided with an emitting part for emitting light and a receiving part for receiving the light reflected by the reflector;
the first reflector comprises a flat reflecting surface and two inclined reflecting surfaces which are rotationally and symmetrically arranged at the outer edge of the flat reflecting surface, and the two inclined reflecting surfaces are arranged along the X axis;
the upper optical sensor comprises two first optical sensors arranged along the X-axis direction, two second optical sensors arranged along the Y-axis direction and two third optical sensors arranged opposite to the inclined reflecting surfaces;
one side of the oblique reflecting surface is close to the transmitting part of the third optical sensor, and the other side of the oblique reflecting surface is far away from the receiving part of the third optical sensor, so that the oblique reflecting surface is relatively inclined towards the transmitting part of the third optical sensor.
2. An optical-based multi-axis force transducer according to claim 1, wherein a plurality of first elastic members are disposed between the first mirror and the cover member and uniformly distributed around the center of the first mirror;
the first adjusting piece is arranged on the sealing cover piece and corresponds to the first elastic piece, the first adjusting piece sequentially penetrates through the sealing cover piece and the first elastic piece, and the head of the first adjusting piece is inserted on the first reflector; the first adjusting piece is rotated to compress or relax the first elastic piece so as to change the distance and/or deflection amount of the first reflecting mirror relative to the first PCB.
3. The optical-based multi-axis force sensor of claim 2 wherein the first elastic member is a spring, an O-ring or a hollow rubber sleeve.
4. The optical-based multi-axis force sensor of claim 2 wherein the resilient cantilever portions are arranged in pairs comprising a first cantilever and a second cantilever;
the first suspension beam and the second suspension beam are arranged in parallel; or the two ends are mutually overlapped to form a triangle, the merging end of the triangle is connected with the bearing part, and the other two ends are connected with the peripheral part.
5. The optical-based multi-axis force sensor of any one of claims 1-4 further comprising a fixture stacked below the sensing element;
one side of the sensing piece facing the fixing piece is provided with a plurality of cushion block parts which are uniformly distributed along the circumferential direction of the peripheral part of the sensing piece, the lower end of each cushion block part is provided with an elastic connecting part which can stretch or contract in the axial direction of each cushion block part, and the elastic connecting parts are connected to the fixing piece;
a second displacement detector for detecting the deflection amount or the movement amount of the bearing part relative to the fixed part is arranged between the fixed part and the bearing part.
6. Optical-principle-based multi-axis force sensor according to claim 5, characterized in that the second displacement detector comprises:
the second reflector is arranged on one side, facing the bearing part, of the fixing piece;
the bearing part faces the second PCB on one side of the fixing part, a plurality of lower optical sensors are arranged on the second PCB, and each lower optical sensor comprises two fourth optical sensors arranged along the X-axis direction and two fifth optical sensors arranged along the Y-axis direction.
7. The optical-principle-based multi-axis force sensor of claim 6, wherein a plurality of second elastic members are uniformly distributed around the center of the second reflector between the second reflector and the fixing member;
the fixed piece is provided with a second adjusting piece corresponding to the second elastic piece, the second adjusting piece sequentially penetrates through the fixed piece and the second elastic piece, and the head of the second adjusting piece is inserted on the second reflector; rotating the second adjusting member to compress or relax the second elastic member to change the distance and/or deflection amount of the second reflecting mirror relative to the second PCB.
8. Optical-based multi-axis force sensor according to claim 6, wherein the upper and lower optical sensors are photodiodes, reflective sensors or wavelength sensors.
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| CN202011193267.9A CN112213009B (en) | 2020-10-30 | 2020-10-30 | Multi-axis force sensor based on optical principle |
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| CN202011193267.9A CN112213009B (en) | 2020-10-30 | 2020-10-30 | Multi-axis force sensor based on optical principle |
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| CN112213009B true CN112213009B (en) | 2021-12-14 |
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| CN113029418B (en) * | 2021-03-09 | 2022-05-17 | 中国科学院自动化研究所 | Multi-dimensional force sensor |
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