CN210981614U - A Differential Capacitive Multidimensional Force Sensor - Google Patents

Abstract

The utility model discloses a differential capacitive multi-dimensional force sensor, which is composed of a sensor body, a lower induction layer, a PCB board and an upper induction layer. The lower sensing layer and the upper sensing layer are connected to the central disc of the sensor body through screws. The PCB board is located between the upper and lower sensing layers, and is fixed on the PCB mounting platform on the inner side of the sensor outer wall, and the parallel-plate capacitive moving electrodes on the upper and lower sensing layers are symmetrically distributed about the PCB board and maintain a certain gap with the PCB board. And form a differential structure parallel electrode capacitor with the parallel plate capacitor electrostatic electrodes on the PCB board and the lower surface. The left and right vertical capacitive static electrodes on the PCB are symmetrically distributed with respect to the vertical capacitive moving electrodes and maintain a certain gap with the vertical capacitive moving electrodes to form a differential structure vertical electrode capacitor. The utility model adopts two differential structure capacitors, which improves the sensitivity, linearity and anti-interference ability of the capacitive multi-dimensional force sensor.

Description

A Differential Capacitive Multidimensional Force Sensor

technical field

The utility model belongs to the technical field of sensors, relates to a force sensor, in particular to a differential capacitive multi-dimensional force sensor.

Background technique

At present, most capacitive six-dimensional force sensors are based on the principle of parallel plate capacitance effect. Relational formula, which converts the value of output force/torque. The capacitive multi-dimensional force sensor has good temperature stability, high impedance, low power, good dynamic response and simple structure. However, its sensitivity is greatly affected by the distance between the plates, and the capacitance value will decrease rapidly with the increase of the distance between the plates, and it is easily disturbed by circuit noise and external environmental factors.

SUMMARY OF THE INVENTION

The purpose of the utility model is to propose a differential capacitive multi-dimensional force sensor in view of the shortcomings of the current capacitive multi-dimensional force sensor, which adopts two differential structure capacitors to improve the anti-interference ability and sensitivity.

A differential capacitive multi-dimensional force sensor includes a sensor body 1, a lower sensing layer 2, a PCB board 3, and an upper sensing layer 4; the sensor body 1 at least includes a deformation beam 5, a sensor outer wall 6 and a PCB board mounting platform 7; One end of the deformation beam 5 is connected to the outer side of the main body center disc 8 of the sensor body 1, and the other end is connected to the inner side of the sensor outer wall 6, and is distributed in a spoke shape; the sensor outer wall 6 is provided with wiring holes 9 for external lead wires; The PCB board mounting table 7 is arranged on the inner side of the sensor outer wall 6, and the PCB board mounting table 7 is provided with a first threaded hole 22; the lower sensing layer 2 and the upper sensing layer 4 are connected to the main body center of the sensor body 1 by screws On the disc 8, the central disc 8 of the main body is provided with a second threaded hole 23 and a countersunk hole 24; the PCB board 3 is mounted on the PCB board mounting table 7; the sensor outer wall 6 is provided with a third threaded hole 25, for the connection between the sensor and the external flange.

The lower sensing layer 2 has lower parallel plate capacitive moving electrodes 10, the number of which is 3, and one end is fixedly connected to the outer side of the central disk 11 of the lower sensing layer, and the other end is suspended. The central disc 11 of the lower induction layer is provided with a through hole 26 for fixing the lower induction layer on the main body central disc 8 of the main body 1 .

The PCB board 3 at least includes a lower parallel plate capacitor electrostatic electrode 12, an upper parallel plate capacitor electrostatic electrode 13, a left vertical capacitor electrostatic electrode 14, a right vertical capacitor electrostatic electrode 15, the number of which is 3, and the PCB board mounting holes. 16. The left vertical capacitive static electrode 14 and the right vertical capacitive static electrode 15 have two layers, which are respectively disposed on the upper and lower surfaces of the PCB board 3 and connected by copper wires in the middle to improve the sensitivity of the sensor.

The upper sensing layer 4 at least includes an upper parallel plate capacitive moving electrode 17 and a vertical capacitive moving electrode 18, the number of which is 3, and one end is fixedly connected to the outer side of the central disk 19 of the upper sensing layer, the other end is suspended, and the upper The center disc 19 of the induction layer is provided with a fourth threaded hole 27 and a fifth threaded hole 28 . The fourth threaded hole 27 is used to fix it together with the lower induction layer 2 on the main body center disc 8 of the main body 1 . The fifth threaded hole 28 is used for the connection between the sensor and the external flange.

The lower parallel plate capacitance moving electrode 10 and the upper parallel plate capacitance moving electrode 17 are symmetrically distributed with respect to the PCB board 3, and both maintain a certain gap with the PCB board 3, and are connected with the lower parallel plate capacitance static electrode 12 and the upper parallel plate capacitance static electrode. 13 form a differential structure parallel electrode type capacitor 20, the number of which is 3 and is evenly distributed around the Z axis; the left vertical capacitive static electrode 14 and the right vertical capacitive static electrode 15 are symmetrically distributed with respect to the vertical capacitive moving electrode 18, And they all keep a certain gap with the vertical capacitor moving electrode 18 to form a differential structure vertical electrode capacitor 21, the number of which is 3 and evenly distributed around the Z axis.

In the differential structure parallel electrode capacitor 20, when the distance between the lower parallel plate capacitor moving electrode 10 and the lower parallel plate capacitor static electrode 12 changes by Δd, the distance between the upper parallel plate capacitor moving electrode 17 and the upper parallel plate capacitor static electrode 13 changes - Δd; for the differential structure vertical electrode capacitor 21, when the distance between the left vertical capacitive static electrode 14 and the vertical capacitive moving electrode 18 changes by Δh, the distance between the right vertical capacitive static electrode 15 and the vertical capacitive moving electrode 18 Change -Δh.

The features and beneficial effects of the present utility model are:

The zero-point capacitance value and the noise capacitance value of a pair of capacitors constituting the differential-structure parallel-electrode capacitor 20 are both C ₀ and C _C , respectively. When the distance between the lower parallel plate capacitor moving electrode 10 and the lower parallel plate capacitor static electrode 12 changes by Δd, the distance between the upper parallel plate capacitor moving electrode 17 and the upper parallel plate capacitor static electrode 13 changes by -Δd. The corresponding capacitances are -ΔC ₁ and ΔC ₂ respectively. Taking the capacitance difference C ₁ -C ₂ as the output signal, the capacitance change is (C ₀ +C _C -ΔC ₁ )-(C ₀ +C _C +ΔC ₂ ) is -ΔC ₁ -ΔC ₂ . The zero point capacitance value and the noise capacitance value of a pair of capacitors constituting the differential vertical electrode type capacitor 21 are both C ₀ ′ and C _C ′, respectively. When the distance between the left vertical capacitive static electrode 14 and the vertical capacitive moving electrode 18 changes by Δh, the distance between the right vertical capacitive static electrode 15 and the vertical capacitive moving electrode 18 changes by -Δh. The corresponding capacitances are -ΔC ₃ and ΔC ₄ respectively, and the capacitance difference C ₃ -C ₄ is used as the output signal, then the capacitance change is (C ₀ '+C _C '-ΔC ₃ )-(C ₀ '+C _C '+ΔC ₄ ) is -ΔC ₃ -ΔC ₄ . Therefore, the use of two differential structure capacitors improves the sensitivity of the capacitive multi-dimensional force sensor, reduces the electrostatic gravitational noise capacitance, and improves the anti-interference ability.

Description of drawings

1 is an exploded view of the overall structure of the utility model;

2 is a schematic diagram of a parallel-electrode capacitor with a differential structure of the present invention;

3 is a schematic diagram of a vertical electrode capacitor with a differential structure of the present invention;

FIG. 4 is a schematic diagram of the Z-axis of the utility model PCB board being rotated 120° counterclockwise in the forward direction;

5 is a schematic diagram of a bottom oblique view of the sensor body of the present invention;

In the accompanying drawings: 1. Sensor body; 2. Lower sensing layer; 3. PCB board; 4. Upper sensing layer; 5. Deformation beam; 6. Sensor outer wall; 7. PCB board mounting platform; 9. Wiring hole; 10. Lower parallel plate capacitive moving electrode; 11. Lower sensing layer center disc; 12. Lower parallel plate capacitive static electrode; 13. Upper parallel plate capacitive static electrode; 14. Left vertical capacitive static electrode ; 15. Right vertical capacitor static electrode; 16. PCB board mounting hole; 17. Upper parallel plate capacitor moving electrode; 18. Vertical capacitor moving electrode; 19. Upper induction layer center disc; 20. Differential structure parallel Electrode type capacitor; 21. Differential structure vertical electrode type capacitor; 22. First threaded hole; 23. Second threaded hole; 24. Countersunk hole; 25. Third threaded hole; 26. Through hole; 27. Section Four threaded holes; 28. Fifth threaded holes.

Detailed ways

For a better understanding of the present invention, the exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in Figures 1 to 5, a differential capacitive multi-dimensional force sensor includes a sensor body 1, a lower sensing layer 2, a PCB board 3, and an upper sensing layer 4; the sensor body 1 at least includes a deformation beam 5, a sensor outer wall 6 and the PCB board mounting platform 7; one end of the deformation beam 5 is connected to the outer side of the central disc 8 of the main body of the sensor body, and the other end is connected to the inner side of the sensor outer wall 6, in a spoke-like distribution; the sensor outer wall 6 is provided with wiring holes 9, for external leads; the PCB board mounting platform 7 is arranged on the inner side of the sensor outer wall 6, and the PCB board mounting platform 7 is provided with a first threaded hole 22; the lower sensing layer 2 and the upper sensing layer 4 are connected by screws On the main body central disc 8 of the sensor body 1, the main body central disc 8 is provided with a second threaded hole 23 and a countersunk hole 24; the PCB board 3 is mounted on the PCB board mounting table 7; the sensor outer wall 6 There is a third threaded hole 25 on it, which is used for the connection between the sensor and the external flange.

The lower sensing layer 2 has lower parallel plate capacitive moving electrodes 10, the number of which is 3, and one end is fixedly connected to the outer side of the central disk 11 of the lower sensing layer, and the other end is suspended. The central disc 11 of the lower induction layer is provided with a through hole 26 for fixing the lower induction layer on the main body central disc 8 of the main body 1 .

The PCB board 3 at least includes a lower parallel plate capacitor electrostatic electrode 12, an upper parallel plate capacitor electrostatic electrode 13, a left vertical capacitor electrostatic electrode 14, a right vertical capacitor electrostatic electrode 15, the number of which is 3, and the PCB board mounting holes. 16. The left vertical capacitive static electrode 14 and the right vertical capacitive static electrode 15 have two layers, which are respectively disposed on the upper and lower surfaces of the PCB board 3 and connected by copper wires in the middle to improve the sensitivity of the sensor.

The upper sensing layer 4 at least includes an upper parallel plate capacitive moving electrode 17 and a vertical capacitive moving electrode 18, the number of which is 3, and one end is fixedly connected to the outer side of the central disk 19 of the upper sensing layer, the other end is suspended, and the upper The center disc 19 of the induction layer is provided with a fourth threaded hole 27 and a fifth threaded hole 28 . The fourth threaded hole 27 is used to fix it together with the lower induction layer 2 on the main body center disc 8 of the main body 1 . The fifth threaded hole 28 is used for the connection between the sensor and the external flange.

The lower parallel plate capacitance moving electrode 10 and the upper parallel plate capacitance moving electrode 17 are symmetrically distributed with respect to the PCB board 3, and both maintain a certain gap with the PCB board 3, and are connected with the lower parallel plate capacitance static electrode 12 and the upper parallel plate capacitance static electrode. 13 form a differential structure parallel electrode type capacitor 20, the number of which is 3 and is evenly distributed around the Z axis; the left vertical capacitive static electrode 14 and the right vertical capacitive static electrode 15 are symmetrically distributed with respect to the vertical capacitive moving electrode 18, And they all keep a certain gap with the vertical capacitor moving electrode 18 to form a differential structure vertical electrode capacitor 21, the number of which is 3 and evenly distributed around the Z axis.

In the differential structure parallel electrode capacitor 20, when the sensor is stressed, the distance between the lower parallel plate capacitive moving electrode 10 and the lower parallel plate capacitive static electrode 12 changes by Δd, and the upper parallel plate capacitive moving electrode 17 and the upper parallel plate capacitance The distance of the static electrode 13 is changed by -Δd. The corresponding capacitances are C ₁ and C ₂ respectively, and the capacitance difference C ₁ -C ₂ is used as the output signal; the differential structure vertical electrode capacitor 21, when the vertical capacitor moving electrode 18 and the left vertical capacitor When the distance of the static electrode 14 changes by Δh, the distance between the right vertical capacitive static electrode 15 and the vertical capacitive moving electrode 18 changes by -Δh, and the corresponding capacitances are C ₃ and C ₄ respectively, and the capacitance difference C ₃ -C ₄ as the output signal.

Its working principle, when the sensor is subjected to any force, it can be decomposed into F _X , F _Y , F _Z , M _X , M _Y , M _Z six-dimensional space force, which deforms the deformed beam, thus forming six pairs of differential forces. The pole pitch of the twelve capacitors of the type structure capacitor is changed, and the values are Δd ₁ , -Δd ₁ , Δh ₁ , -Δh ₁ , Δd ₂ , -Δd ₂ , Δh ₂ , -Δh ₂ , Δd ₃ , -Δd ₃ , Δh ₃ , -Δh ₃ , the corresponding capacitance change values are -ΔC ₁ , ΔC ₂ , -ΔC ₃ , ΔC ₄ , -ΔC ₅ , ΔC ₆ , -ΔC ₇ , ΔC ₈ , -ΔC ₉ , ΔC ₁₀ , -ΔC ₁₁ , ΔC ₁₂ , and ΔC ₁ ≈ΔC ₂ , ΔC ₃ ≈ΔC ₄ , ΔC ₅ ≈ΔC ₆ , ΔC ₇ ≈ΔC ₈ , ΔC ₉ ≈ΔC ₁₀ , and ΔC ₁₁ ≈ΔC ₁₂ .

Mathematical relationship between plate distance and capacitance of parallel plate electrode capacitors:

Among them, ε is the dielectric constant of the medium between the two polar plates; S is the relative effective area between the two polar plates; d is the distance between the two polar plates.

It can be seen from the formula that when the distance d ₀ between the plates changes by Δd, the change of the initial capacitance C ₀ is ΔC ₁ , as follows:

极小时，由泰勒公式展开得：when

extremely small, it is expanded by Taylor's formula:

进行线性拟合，则变极距电容器灵敏度计算公式为：ready to use

Perform linear fitting, then the formula for calculating the sensitivity of the variable pole distance capacitor is:

When a differential structure is used, that is, when one capacitor pole pitch d changes by Δd, the other capacitor pole pitch d changes by -Δd, and the capacitance changes are respectively -ΔC ₁ and ΔC ₂ , and ΔC ₁ ≈ΔC ₂ . And take the tolerance C ₁ -C ₂ of the two capacitors as the output signal, then the capacitance change ΔC=(C ₀ +C _C -ΔC ₁ )-(C ₀ +C _C +ΔC ₂ )=-ΔC ₁ -ΔC ₂ = -2ΔC ₁ , so the sensitivity is:

提高到

同时还减小了噪声电容C_C。It can be seen from the above formula that when the differential structure is adopted, the sensitivity of the parallel electrode capacitor is given by

improve to

It also reduces the noise capacitance C _C .

Mathematical relationship between vertical electrode capacitor plate spacing and capacitance:

Among them, h is the distance between the two poles; H is the height of the vertical electrode; W is the width of the vertical electrode; ε is the dielectric constant of the medium between the two polar plates.

It can be seen from the above formula that when the plate spacing h ₀ changes Δh, the change of the initial capacitance C ₀ ' is ΔC ₃ , that is:

极小时，由泰勒公式展开得：when

extremely small, it is expanded by Taylor's formula:

进行线性拟合，其灵敏度为：i.e. available

A linear fit is performed with a sensitivity of:

When a differential structure is used, that is, when one capacitor pole pitch h changes Δh, the other capacitor pole pitch h changes -Δh, and the capacitance changes are -ΔC ₃ and ΔC ₄ respectively, and ΔC ₃ ≈ΔC ₄ . And take the tolerance C ₃ -C ₄ of the two capacitors as the output signal, then the capacitance change ΔC=(C ₀ '+C _C '-ΔC ₃ )-(C ₀ '+C _C '+ΔC ₄ )=- ΔC ₃ -ΔC ₄ =-2ΔC ₄ , so the sensitivity is:

提高到

同时还减小了噪声电容C_C'。It can be seen from the above formula that when the differential structure is adopted, the sensitivity of the vertical plate capacitor is given by

improve to

It also reduces the noise capacitance C _C '.

Finally, the capacitance values of six pairs of differential structure capacitors C ₁ -C ₂ , C ₃ -C ₄ , C ₅ -C ₆ , C ₇ -C ₈ , C ₉ -C ₁₀ , C ₁₁ -C ₁₂ are used as output signals, And through the test, the 6×6 decoupling matrix A can be obtained, and the following decoupling formula is established:

F=AΔC

In the formula, F=(F _X ,F _Y ,F _Z ,M _X ,M _Y ,M _Z ) ^T ,ΔC=(C ₁ -C ₂ ,C ₃ -C ₄ ,C ₅ -C ₆ ,C ₇ - C ₈ ,C ₉ -C ₁₀ ,C ₁₁ -C ₁₂ ) ^T

F _X , F _Y , and F _Z represent the force in the X direction, the force in the Y direction, and the force in the Z direction, respectively, and the unit is N;

M _X , M _Y , and M _Z represent the moment in the X direction, the moment in the Y direction, and the moment in the Z direction, respectively, and the unit is N·m.

Finally, it is explained that the above are only the preferred embodiments of the present utility model, and the present utility model is not limited to the above embodiments, and various modifications or deformations can also be made. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. All equivalent technical changes studied using the principles of the present invention are included in the scope of the patent of the present invention.

Claims (7)

1. A differential capacitive multi-dimensional force sensor, characterized in that: it at least comprises a sensor body (1), a lower sensing layer (2), a PCB board (3), and an upper sensing layer (4); the sensor body ( 1) At least it includes a deformation beam (5), an outer wall of the sensor (6) and a PCB board mounting platform (7); one end of the deformation beam (5) is connected to the outside of the central disc (8) of the main body of the sensor body, and the other end is connected to the sensor The inner side of the outer wall (6) is in a spoke-like distribution; the outer wall (6) of the sensor is provided with a wiring hole (9); the PCB board mounting platform (7) is arranged on the inner side of the outer wall (6) of the sensor; the lower sensor The layer (2) and the upper sensing layer (4) are connected to the main body center disc (8) of the sensor main body (1) by screws; the PCB board (3) is mounted on the PCB board mounting table (7). 2. A differential capacitive multi-dimensional force sensor according to claim 1, characterized in that: the lower sensing layer (2) is provided with a lower parallel plate capacitive moving electrode (10), one end of which is fixedly connected to the lower sensing layer Outside the central disc (11), the other end is suspended. 3. A differential capacitive multi-dimensional force sensor according to claim 2, characterized in that: the PCB board (3) at least comprises a lower parallel plate capacitive static electrode (12), an upper parallel plate capacitive static electrode (13) ), a left vertical capacitive electrostatic electrode (14), a right vertical capacitive electrostatic electrode (15) and a PCB board mounting hole (16). 4. A differential capacitive multi-dimensional force sensor according to claim 3, characterized in that: the upper sensing layer (4) at least comprises an upper parallel plate capacitive moving electrode (17), a vertical capacitive moving electrode (18) ), one end of which is fixedly connected to the outer side of the central disc (19) of the upper induction layer, and the other end is suspended. 5. A differential capacitive multi-dimensional force sensor according to claim 4, characterized in that: the lower parallel plate capacitive moving electrode (10) and the upper parallel plate capacitive moving electrode (17) are about the PCB board (3) Symmetrically distributed and maintain a certain gap with the PCB board (3), and form a differential structure parallel electrode type with the lower parallel plate capacitive electrostatic electrode (12) and the upper parallel plate capacitive electrostatic electrode (13) on the PCB board (3) Capacitor (20); the left vertical capacitive static electrode (14) and the right vertical capacitive static electrode (15) are symmetrically distributed with respect to the vertical capacitive moving electrode (18), and both remain with the vertical capacitive moving electrode (18) A certain gap is formed to form a differential structure vertical electrode type capacitor (21). 6. A differential capacitive multi-dimensional force sensor according to claim 5, characterized in that: the differential structure parallel electrode capacitor (20), the lower parallel plate capacitive moving electrode (10) and the lower parallel plate When the distance of the capacitive static electrode (12) changes by Δd, the distance between the upper parallel plate capacitive moving electrode (17) and the upper parallel plate capacitive static electrode (13) changes by -Δd, and the capacitance difference C ₁ -C ₂ is used as the output Signal; In the differential structure vertical electrode capacitor (21), when the distance between the left vertical capacitor static electrode (14) and the vertical capacitor movable electrode (18) changes by Δh, the right vertical capacitor static electrode (15) is connected to the vertical capacitor static electrode (15) and the vertical capacitor static electrode (15). The distance of the capacitive moving electrode (18) changes by -Δh, and the capacitance difference C ₃ -C ₄ is used as an output signal. 7 . The differential capacitive multi-dimensional force sensor according to claim 1 , wherein two types of differential structure capacitors are used. 8 .

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