Tactile force sensor and mechanical arm

Abstract

The utility model relates to the technical field of force sensors, and discloses a tactile force sensor and a mechanical arm, the tactile force sensor comprises at least one tactile force sensing detection unit, each tactile force sensing detection unit comprises a housing forming a closed chamber filled with a deformable filler, and the housing is provided with at least one elastic part; the shell comprises a contact part which is at least partially flexible and protrudes outwards, and the contact part can deform when making contact with a contact object. And the MEMS pressure chip is arranged on the inner wall of the shell and is used for detecting the pressure between the touch force sensing detection unit and a contact object. The touch force sensor disclosed by the utility model has better temperature drift resistance and linearity, in addition, compared with a strain gauge type force sensor, the MEMS pressure chip with the same length and width has a larger measuring range, and the touch force sensor is suitable for high-precision and high-stability application scenes.

Description

Technical Field

[0001] The utility model relates to the technical field of force sensors, in particular to a tactile force sensor and a mechanical arm. Background Art

[0002] Most of the common force sensors on the market currently use a strain gauge design. Although this type of force sensor is low-cost and easy to implement, it has exposed many defects in actual applications. First, the linearity of the strain gauge force sensor is poor, and errors are prone to occur during the measurement process, especially in high-precision detection scenarios, which makes it difficult to meet the needs. Secondly, this type of sensor has weak resistance to temperature drift, and temperature changes have a significant impact on the measurement results, resulting in large errors in the detection results. In addition, the range of the strain gauge force sensor is limited and cannot meet the needs of a large range of detection. These problems make the existing strain gauge force sensor unable to be used in application scenarios with high precision and high stability requirements, and cannot meet the market demand for high-performance force sensors. Utility Model Content

[0003] Based on the above, the purpose of the present invention is to provide a tactile force sensor and a robotic arm, which solve the problems of poor linearity, weak temperature drift resistance and small range of existing strain gauge force sensors, and is suitable for application scenarios with high precision and high stability.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A tactile force sensor includes at least one tactile force sensing detection unit, each of the tactile force sensing detection units including:

[0006] a housing forming a closed chamber filled with a deformable filler, the housing including a contact portion that is at least partially flexible and protrudes outward, the contact portion being deformable when in contact with a contact object;

[0007] The MEMS pressure chip is arranged on the inner wall of the shell and is used to detect the pressure between the tactile force sensing unit and the contact object.

[0008] As a preferred solution for a tactile force sensor, the MEMS pressure chip includes a piezoresistor, a silicon substrate and a cap. The piezoresistor is formed on the silicon substrate, the cap cover is arranged on the silicon substrate and the two form a pressure cavity. The side of the silicon substrate facing away from the cap is provided with a force-bearing groove facing the pressure cavity, and the cap is fixed on the inner wall of the shell.

[0009] As a preferred solution for a tactile force sensor, the number of the piezoresistors is four, and the four piezoresistors are electrically connected to form a Wheatstone bridge connection. The MEMS pressure chip also includes four first metal PADs, two of which are electrically connected to the two input ends of the Wheatstone bridge respectively, and the other two first metal PADs are electrically connected to the two output ends of the Wheatstone bridge. Four connecting holes are provided on the cap, and each connecting hole corresponds to one of the first metal PADs.

[0010] As a preferred solution of the tactile force sensor, the tactile force sensing detection unit further includes a heating resistor, which is arranged on the inner wall of the shell and can generate heat at a preset power.

[0011] As a preferred solution of the tactile force sensor, the heating resistor is a heating coil, the orthographic projection of the heating coil is a circular coil composed of at least two concentric circles, and the circular coil includes a plurality of circular arc coils connected in sequence.

[0012] As a preferred solution of a tactile force sensor, the shell also includes a base and a fixed shell, one end of the fixed shell is fixed on the base, and the other end of the fixed shell is connected to the contact part, the base, the fixed shell and the contact part form the closed chamber, and the MEMS pressure chip is arranged on the base.

[0013] As a preferred solution of the tactile force sensor, the contact portion is a polydimethylsiloxane film, and the shell is a flexible film composed of the polydimethylsiloxane film.

[0014] As a preferred embodiment of a tactile force sensor, the tactile force sensor further includes a first partition, in which a plurality of independent first placement grooves arranged in rows and columns are formed, each of which is provided with a tactile force sensing detection unit, and each of the tactile force sensing detection units can independently detect the pressure between the contact object and the contact object.

[0015] As a preferred embodiment of a tactile force sensor, the tactile force sensor further includes a second partition, in which a plurality of independent second placement grooves in a honeycomb shape are formed, each of which is provided with a tactile force sensing detection unit, and each of the tactile force sensing detection units can independently detect the pressure between the contact object and the contact object.

[0016] A robotic arm comprises a robotic finger, a robotic palm, and the tactile force sensor described in any of the above schemes, wherein the tactile force sensor is arranged on the robotic finger and / or the robotic palm.

[0017] The beneficial effects of the utility model are:

[0018] The tactile force sensor disclosed by the present invention includes a flexible contact portion that enables the tactile force sensor to better contact the contact object. During detection, the pressure between the contact object and the shell is transmitted to the MEMS pressure chip through the filler. The force detected by the MEMS pressure chip is the pressure between the contact object and the shell. The MEMS pressure chip is less affected by temperature and has good resistance to temperature drift and linearity. In addition, compared with strain gauge force sensors of the same length and width, the MEMS pressure chip has a larger range and is suitable for high-precision and high-stability application scenarios, which can meet the market demand for high-performance force sensors.

[0019] The mechanical arm disclosed in the utility model has the advantages of good linearity, strong resistance to temperature drift and large measuring range due to the use of a tactile force sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0021] Figure 1 is a cross-sectional view of a tactile force sensing detection unit of a tactile force sensor provided by a specific embodiment of the present utility model;

[0022] Figure 2 Schematic diagram of a MEMS pressure chip of a tactile force sensor provided by a specific embodiment of the present utility model;

[0023] Figure 3 2 is a cross-sectional view of a MEMS pressure chip of a tactile force sensor provided by a specific embodiment of the present utility model;

[0024] Figure 4 Schematic diagram of a MEMS pressure chip of a tactile force sensor provided by a specific embodiment of the present invention with the cap removed;

[0025] Figure 5 It is a projection diagram of a heating resistor of a tactile force sensor provided by a specific embodiment of the present utility model;

[0026] Figure 6 is a cross-sectional view of a tactile force sensing detection unit of a tactile force sensor provided in another embodiment of the present invention;

[0027] Figure 7Schematic diagram of a first diaphragm of a tactile force sensor provided in a specific embodiment of the present invention;

[0028] Figure 8 is a schematic diagram of a first diaphragm of a tactile force sensor provided in another embodiment of the present invention;

[0029] Figure 9 It is a schematic diagram of a partial structure of a robotic arm provided by a specific embodiment of the present utility model.

[0030] In the picture:

[0031] 100, tactile force sensing unit; 11, housing; 110, closed chamber; 111, contact portion; 112, base; 113, fixed housing; 12, MEMS pressure chip; 120, pressure chamber; 121, piezoresistor; 122, silicon substrate; 1220, force-bearing groove; 123, cap; 1230, connection hole; 124, first metal PAD; 125, temperature electrode; 126, second metal PAD; 13, heating resistor;

[0032] 2. First partition; 20. First placement groove;

[0033] 3. Second partition; 30. Second placement slot;

[0034] 41. Robotic hand; 42. Robotic fingers. DETAILED DESCRIPTION

[0035] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved more clearly, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0036] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0037] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0038] This embodiment provides a tactile force sensor, such as Figures 1 to 7 As shown, it includes twenty-five tactile force sensing detection units 100, each of which includes a shell 11 and a MEMS pressure chip 12. The shell 11 forms a closed chamber 110, and the closed chamber 110 is filled with a liquid filler. The shell 11 includes a contact portion 111 that is at least partially flexible and protrudes outward. The contact portion 111 can deform when in contact with a contact object; in the absence of external force, the contact portion 111 can also be restored to an outward protruding structure under the pressure of the filler. The MEMS pressure chip 12 is arranged on the inner wall of the shell 11 and is used to detect the pressure between the tactile force sensing detection unit 100 and the contact object. It should be noted that in other embodiments of the present invention, the number of tactile force sensing detection units 100 included in each tactile force sensor is not limited to the twenty-five in this embodiment, and can also be one, two or other numbers, depending on actual needs.

[0039] In this embodiment, the closed chamber 110 is filled with oil. When the contact portion 111 contacts the contact object and pressure is applied, the contact portion 111 deforms and squeezes the oil in the closed chamber 110. The force generated by the oil pressure acts on the MEMS pressure chip 12, which can detect this force and thus detect pressure. In other embodiments, the filler can also be other liquids such as water, or gaseous filler gas, or solid gel, etc., depending on actual needs.

[0040] The tactile force sensor provided in this embodiment includes a flexible contact portion 111, which enables the tactile force sensor to better contact the contact object. During detection, the pressure between the contact object and the shell 11 is transmitted to the MEMS pressure chip 12 through the filler. The force detected by the MEMS pressure chip 12 is the pressure between the contact object and the shell 11, ensuring that the MEMS pressure chip 12 is less affected by temperature and has good resistance to temperature drift and linearity. In addition, compared with strain gauge force sensors of the same length and width, the MEMS pressure chip 12 has a larger range, is suitable for high-precision and high-stability application scenarios, and can meet the market demand for high-performance force sensors.

[0041] like Figure 3 and Figure 4 As shown, the MEMS pressure chip 12 provided in this embodiment includes a piezoresistor 121, a silicon substrate 122 and a cap 123. The piezoresistor 121 is formed on the silicon substrate 122, and the cap 123 is covered on the silicon substrate 122 and the two form a pressure chamber 120. A force groove 1220 facing the pressure chamber 120 is provided on the side of the silicon substrate 122 away from the cap 123, and the cap 123 is fixed on the inner wall of the shell 11.

[0042] Specifically, if Figure 4 As shown, the number of piezoresistors 121 in this embodiment is four, and the four piezoresistors 121 are electrically connected to form a Wheatstone bridge connection. The MEMS pressure chip 12 also includes four first metal PADs 124, two of which are electrically connected to the two input ends of the Wheatstone bridge, and the other two first metal PADs 124 are electrically connected to the two output ends of the Wheatstone bridge.

[0043] like Figure 2 As shown, the cap 123 is provided with four connection holes 1230, each corresponding to a first metal PAD 124. Specifically, the cap 123 is a rectangular parallelepiped cap, with the four connection holes 1230 located at its four corners. Each connection hole 1230 directly faces a first metal PAD 124, facilitating the subsequent routing of the connection wires connected to the first metal PAD 124 through the connection holes 1230. It should be noted that the base 112 of this embodiment also has four avoidance holes corresponding to the four connection holes 1230 to ensure that the connection wires routed from the connection holes 1230 can pass through the avoidance holes.

[0044] Furthermore, if Figure 4 As shown, each tactile force sensing detection unit 100 further includes a temperature electrode 125 and two second metal PADs 126. The temperature electrode 125 is fixed to the inner wall of the housing 11 and is configured to detect the temperature of the contact object. The two second metal PADs 126 are respectively connected to the ends of the temperature electrode 125. It should be noted that the number of temperature electrodes 125 in each tactile force sensing detection unit 100 is not limited to one in this embodiment, and can also be two or more. This embodiment does not impose any limitation and is specifically set according to actual needs.

[0045] The tactile force sensing unit 100 of this embodiment further includes a heating resistor 13, which is disposed on the inner wall of the housing 11 and is capable of generating heat at a preset power. The heating resistor 13 is a heating coil, which is attached to the inner wall of the housing 11. Figure 5As shown, the positive projection of the heating coil is a circular coil composed of four concentric circles, and the circular coil includes a plurality of circular arc coils connected in sequence. Specifically, when the temperature detected by the temperature electrode 125 is lower than the preset temperature, the heating resistor 13 is configured to generate heat at a preset power, thereby heating the tactile force sensing detection unit 100, so that the MEMS pressure chip 12 measures the pressure between the contact object at a more suitable temperature, further improving the detection accuracy of the tactile force sensing detection unit 100. It should be noted that in other embodiments of the present invention, the tactile force sensing detection unit 100 can also be provided with no heating resistor 13 according to actual needs, which is specifically determined based on the usage scenario of the tactile force sensing detection unit 100.

[0046] like Figure 1 As shown, the housing 11 of this embodiment further includes a base 112 and a fixed shell 113. One end of the fixed shell 113 is fixed to the base 112 and the two are sealed together. The other end of the fixed shell 113 is sealed to the contact portion 111. The base 112, fixed shell 113, and contact portion 111 form a closed chamber 110, and the MEMS pressure chip 12 is disposed on the base 112. During pressure detection, the contact portion 111 deforms and bends inward. The filler within the closed chamber 110 prevents the contact portion 111 from contacting the MEMS pressure chip 12, reducing the probability of damage caused by squeezing the MEMS pressure chip 12 during detection, thereby helping to extend the service life of the MEMS pressure chip 12. The base 112 and fixed shell 113 of this embodiment can both be formed of metal, polymer, fabric, glass, ceramic, other materials, or a combination of these materials. The base 112 and fixed shell 113 can also be different. For example, the base 112 can be a ceramic base and the fixed shell 113 can be a metal shell, or both can be made of other materials, without limitation.

[0047] It should be noted that the MEMS pressure chip 12 of this embodiment is a square chip with a minimum side length of 0.5 mm, which makes the volume of the final processed tactile force sensing detection unit 100 very small, facilitating the miniaturization design of the overall structure.

[0048] Specifically, the contact portion 111 of this embodiment is a polydimethylsiloxane film, that is, the contact portion 111 is a deformable film made of polydimethylsiloxane. This flexible deformable film can better contact the contact object, so that the tactile force sensing detection unit 100 has a larger contact area with the contact object, which is beneficial to the detection of pressure. In other embodiments, the housing 11 can also be only Figure 6 The flexible membrane shown is formed by a polydimethylsiloxane membrane; alternatively, the shell 11 is an elastic shell formed by a TRP thermoplastic elastomer or other flexible materials. This embodiment does not limit this and is specifically configured according to actual needs.

[0049] Specifically, if Figure 7 As shown, the tactile force sensor of this embodiment further includes a first partition plate 2, within which are formed twenty-five independent first placement slots 20 arranged in five rows and five columns. Each first placement slot 20 houses a tactile force sensing detection unit 100, and each tactile force sensing detection unit 100 is capable of independently detecting pressure against a contact object. In other words, when detecting pressure against a contact object, each tactile force sensing detection unit 100 is capable of independently detecting pressure, and adjacent tactile force sensing detection units 100 do not affect each other and are not squeezed by adjacent tactile force sensing detection units 100.

[0050] In other embodiments, Figure 8 As shown, the tactile force sensor includes a second partition 3, in which a plurality of honeycomb-shaped and independent second placement grooves 30 are formed. Each second placement groove 30 is provided with a tactile force sensing detection unit 100, and each tactile force sensing detection unit 100 can independently detect the pressure between the contact object. It should be noted that the number of second placement grooves 30 in the second partition 3 is not limited to the limitation of this embodiment, and can also be other numbers, which are specifically set according to actual needs. In other embodiments, the tactile force sensor also includes a third partition, in which a plurality of independent third placement grooves are formed. The third placement grooves are circular, triangular, other polygonal, elliptical or other shapes. This embodiment does not limit it and it is specifically set according to actual needs.

[0051] This embodiment also provides Figure 9 The robotic arm shown includes a robotic palm 41, robotic fingers 42, and the aforementioned tactile force sensors. The tactile force sensors of this embodiment are disposed on the inner side of the robotic palm 41, and a tactile force sensing detection unit 100 is disposed on the inner side of each robotic finger 42. In other embodiments, at least two tactile force sensing detection units 100 may be disposed on the inner side of each robotic finger 42. The number of tactile force sensing detection units 100 included in the tactile force sensor on the inner side of the robotic palm 41 is not limited to the twenty-five of this embodiment, and may be other numbers, depending on actual needs.

[0052] The robotic arm provided in this embodiment has the advantages of good linearity, strong resistance to temperature drift, and a large measuring range due to the use of a tactile force sensor.

[0053] Note that the above are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions are possible for those skilled in the art without departing from the scope of protection of the present invention. Therefore, while the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A tactile force sensor, characterized in that: The device comprises at least one tactile force sensing detection unit, each of which comprises: a housing forming a closed chamber filled with a deformable filler, the housing including a contact portion that is at least partially flexible and protrudes outward, the contact portion being deformable when in contact with a contact object; The MEMS pressure chip is arranged on the inner wall of the shell and is used to detect the pressure between the tactile force sensing unit and the contact object.

2. The tactile force sensor according to claim 1, wherein The MEMS pressure chip includes a piezoresistor, a silicon substrate and a cap. The piezoresistor is formed on the silicon substrate, the cap is covered on the silicon substrate and the two form a pressure cavity. A force-bearing groove facing the pressure cavity is provided on the side of the silicon substrate away from the cap, and the cap is fixed on the inner wall of the shell.

3. The tactile force sensor according to claim 2, wherein There are four piezoresistors, and the four piezoresistors are electrically connected to form a Wheatstone bridge connection. The MEMS pressure chip also includes four first metal PADs, two of which are electrically connected to the two input ends of the Wheatstone bridge respectively, and the other two are electrically connected to the two output ends of the Wheatstone bridge. Four connecting holes are provided on the cap, and each connecting hole corresponds to one of the first metal PADs.

4. The tactile force sensor according to claim 1, wherein The tactile force sensing detection unit further includes a heating resistor, which is disposed on an inner wall of the housing and is capable of generating heat at a preset power.

5. The tactile force sensor according to claim 4, wherein: The heating resistor is a heating coil, and the orthographic projection of the heating coil is a circular coil composed of at least two concentric circles. The circular coil includes a plurality of circular arc coils connected in sequence.

6. The tactile force sensor according to claim 1, wherein The shell also includes a base and a fixed shell, one end of the fixed shell is fixed on the base, and the other end of the fixed shell is connected to the contact part. The base, the fixed shell and the contact part form the closed chamber, and the MEMS pressure chip is arranged on the base.

7. The tactile force sensor according to claim 1, wherein The contact portion is a polydimethylsiloxane film, and the shell is a flexible film composed of the polydimethylsiloxane film.

8. The tactile force sensor according to claim 1, wherein The tactile force sensor also includes a first partition, in which a plurality of independent first placement grooves arranged in rows and columns are formed. Each of the first placement grooves is provided with a tactile force sensing detection unit, and each of the tactile force sensing detection units can independently detect the pressure between the contact object.

9. The tactile force sensor according to claim 1, wherein The tactile force sensor also includes a second partition, in which a plurality of independent second placement grooves in a honeycomb shape are formed. Each of the second placement grooves is provided with a tactile force sensing detection unit, and each of the tactile force sensing detection units can independently detect the pressure between the contact object.

10. A robotic arm, characterized in that: The invention comprises a mechanical finger, a mechanical palm, and the tactile force sensor according to any one of claims 1 to 9, wherein the tactile force sensor is arranged on the mechanical finger and / or the mechanical palm.

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