Flexible three-dimensional force sensor

Abstract

The invention discloses a flexible three-dimensional force sensor, and the sensor comprises a housing which is an elastic part and is in the shape of a hemisphere or a semi-ellipsoid; the flexible circuit printed board is installed in the shell, a light source and a plurality of photosensitive sensors are installed on the flexible circuit printed board, the light source is located in the center of the shell, and the photosensitive sensors are distributed around the light source in a circumferential array mode; the shielding structure is mounted on the inner wall of the shell; wherein the space between the shell and the flexible printed circuit board is sealed with air, and the shielding structure can extend into the space between the light source and the corresponding photosensitive sensor to block light path propagation so as to trigger the corresponding photosensitive sensor. The flexible three-dimensional force sensor is simple in structure, complex design is avoided, the production cost can be reduced, and the size can be conveniently reduced so as to be applied to a micro machine; the inner cavity of the shell is sealed with air, so that the flexible three-dimensional force sensor can bear larger pressure, and the pressure detection range is larger than that of a traditional flexible three-dimensional force sensor. The invention relates to the technical field of sensors.

Description

Technical Field

[0001] This application relates to the technical field of sensors, and particularly to a flexible three-dimensional force sensor. Background Art

[0002] Three-dimensional force sensors can obtain richer three-dimensional space force information than one-dimensional force sensors, including normal force and tangential forces in two directions. This enables three-dimensional force sensors to show broad application prospects in the fields of robot perception, control, and operation. With the continuous improvement of the compliance and intelligence level of robots, three-dimensional force sensors play a crucial role in realizing safe and friendly interactions between robots and between humans and robots.

[0003] Currently, most existing three-dimensional force sensors are rigid devices, which have disadvantages such as large size and high cost, and most use strain gauge technology to detect multi-dimensional forces. These rigid three-dimensional force sensors are prone to irreversible damage due to exceeding the measurement range, and there are difficulties in integrating with robot systems such as flexible manipulators. In recent years, the research on three-dimensional force sensors has gradually developed towards flexibility, but still faces problems such as small detection range and high manufacturing difficulty, which makes them not suitable for most robot operation tasks. Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the prior art. For this purpose, this application proposes a flexible three-dimensional force sensor, which can solve the problems of large volume, high production cost, complex structure, and small detection range of existing three-dimensional force sensors.

[0005] The flexible three-dimensional force sensor according to the first aspect embodiment of this application includes:

[0006] A housing, which is an elastic member, and the housing is in the shape of a hemisphere or a semi-ellipsoid;

[0007] A flexible circuit printed board, which is installed inside the housing, and a light source and a plurality of photosensitive sensors are installed on the flexible circuit printed board. The light source is located at the center of the housing, and each of the photosensitive sensors is distributed in a circular array around the light source;

[0008] A shielding structure, the number of which is the same as the number of the photosensitive sensors. The shielding structure is arranged in one-to-one correspondence with the photosensitive sensors, and the shielding structure is installed on the inner wall of the housing;

[0009] Wherein, the space between the housing and the flexible circuit printed board is sealed with air. When the housing is deformed under the influence of an external force, it can drive the shielding structure to extend between the light source and the corresponding photosensitive sensor, and the shielding structure blocks the light path propagation to trigger the corresponding photosensitive sensor.

[0010] The flexible three-dimensional force sensor according to the embodiments of the present application has at least the following beneficial effects: The structure of this flexible three-dimensional force sensor is simple, avoiding complex designs. The elastic outer shell and circuit board are easy to manufacture, which can reduce production costs and is also convenient for reducing the volume for application in micro machinery. The inner cavity of the outer shell is sealed with air, which can withstand greater pressure, and thus the pressure detection range is also larger than that of traditional flexible three-dimensional force sensors.

[0011] According to some embodiments of the present application, the outer shell is an opaque silicone elastic shell.

[0012] According to some embodiments of the present application, ribs are provided on the outer side of the outer shell, and the ribs are used to strengthen the structural strength of the outer shell.

[0013] According to some embodiments of the present application, the shielding structure is plate-shaped and horizontally disposed between the light source and the corresponding photosensitive sensor.

[0014] According to some embodiments of the present application, when the outer shell is not subjected to external force, the bottom of the shielding structure and the top of the photosensitive sensor are at the same height.

[0015] According to some embodiments of the present application, the number of both the photosensitive sensors and the shielding structures is four.

[0016] According to some embodiments of the present application, the number of the light sources is at least two, and the light sources together form a light-emitting array.

[0017] According to some embodiments of the present application, the light source is an infrared emitting diode with a wavelength of 940 nm and an emission angle of 140°.

[0018] According to some embodiments of the present application, the photosensitive sensor is an infrared photosensitive diode with a photosensitive wavelength range of 350 to 1120 nm and a receiving angle of 120°.

[0019] According to some embodiments of the present application, the distance between the photosensitive sensor and the light source is 1.6 ± 0.15 mm.

[0020] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings are used to provide a further understanding of the technical solutions disclosed in the present application, and constitute a part of the specification. Together with the embodiments disclosed in the present application, they are used to explain the technical solutions of the present disclosure, and do not constitute a limitation to the technical solutions disclosed in the present application.

[0022] Figure 13D view of the flexible 3D force sensor according to the embodiment of the present application;

[0023] Figure 2 Exploded view of the flexible 3D force sensor according to the embodiment of the present application;

[0024] Figure 3 Cross-sectional view of the flexible 3D force sensor according to the embodiment of the present application;

[0025] Figure 4 Test diagrams of the normal force response range, hysteresis and sensitivity of the flexible 3D force sensor according to the embodiment of the present application;

[0026] Figure 5 Test diagram of the minimum force response of the flexible 3D force sensor according to the embodiment of the present application;

[0027] Figure 6 Test diagrams of the response time and recovery time of the flexible 3D force sensor according to the embodiment of the present application.

[0028] Reference numerals: 100 - housing, 110 - rib, 200 - flexible circuit printed board, 300 - light source, 400 - photosensitive sensor, 500 - shielding structure. Detailed implementation manners

[0029] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application.

[0030] In the description of the present application, it should be understood that for the orientation description, such as up, down, front, back, left, right, etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0031] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, exceeding, etc. are understood as not including the present number, and above, below, within, etc. are understood as including the present number. If there is a description of first and second, it is only for the purpose of distinguishing technical features and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0032] In the description of this application, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in combination with the specific content of the technical solution.

[0033] In the description of this application, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0034] The three-dimensional force sensor can obtain richer three-dimensional space force information than the one-dimensional force sensor, including the normal force and the tangential forces in two directions. This enables the three-dimensional force sensor to show broad application prospects in the fields of robot perception, control, and operation. With the continuous improvement of the compliance and intelligence level of robots, the three-dimensional force sensor plays a crucial role in realizing safe and friendly interactions between robots and between humans and robots.

[0035] Currently, most of the existing three-dimensional force sensors are rigid devices, which have disadvantages such as large size and high cost, and most of them use strain gauge technology to detect multi-dimensional forces. These rigid three-dimensional force sensors are prone to irreversible damage due to exceeding the measurement range, and there are difficulties in integrating with robot systems such as flexible manipulators. In recent years, the research on three-dimensional force sensors has gradually developed towards the flexible direction, but still faces problems such as small detection range and high manufacturing difficulty, which makes it not suitable for most robot operation tasks.

[0036] In response to this, this application proposes a flexible three-dimensional force sensor. The structure of this flexible three-dimensional force sensor is simple, avoiding complex designs. The elastic shell and circuit board are easy to manufacture, which can reduce production costs and is also convenient for reducing the volume for application in micro-mechanisms; the inner cavity of the shell is sealed with air, which can withstand greater pressure, and thus the pressure detection range is also larger than that of traditional flexible three-dimensional force sensors.

[0037] The flexible three-dimensional force sensor in the embodiment of this application includes a shell 100, a flexible circuit printed board 200, a light source 300, a photosensitive sensor 400, and an occlusion structure 500. Among them, referring to Figure 1 , the shell 100 and the flexible circuit printed board 200 together constitute the main structure of this flexible three-dimensional force sensor. A sealed cavity is provided between the shell 100 and the flexible circuit printed board 200. Referring to Figure 2The light source 300, the photosensor 400 and the shielding structure 500 are all arranged in the sealed cavity.

[0038] Reference Figure 3 The housing 100 is used to withstand external forces. It is an elastic part that will deform when subjected to force, thereby triggering the internal shielding structure 500 to move, thereby shielding the light emitted by the light source 300. The photosensor 400 detects the change in light intensity, triggers and generates an electrical signal to the flexible circuit printed board 200, and the flexible circuit printed board 200 then transmits the electrical signal to the external electronic device to complete the force detection work.

[0039] Specifically, the housing 100 is an elastic member and is in the shape of a hemisphere or a hemi-ellipsoid. The purpose of designing the housing 100 as a hemisphere or a hemi-ellipsoid structure is that when the housing is subjected to forces in different directions, it has a similar deformation mode, thereby avoiding deviations in force detection caused by different deformations in certain directions of the housing 100.

[0040] The flexible circuit printed board 200 is installed inside the housing 100, and a cavity is enclosed between the flexible circuit printed board 200 and the housing 100. A light source 300 and a plurality of photosensitive sensors 400 are installed on the flexible circuit printed board 200, and the light source 300 and each photosensitive sensor 400 are arranged in the cavity. It is worth noting that the light source 300 is located in the center of the housing 100, and each photosensitive sensor 400 is distributed in a circular array around the light source 300. The number of shielding structures 500 is consistent with the number of photosensitive sensors 400, and each shielding structure 500 is arranged in a one-to-one correspondence with the photosensitive sensor 400. The shielding structure 500 is installed to the inner wall of the housing 100, and can drive the shielding structure 500 to move when the housing 100 is squeezed.

[0041] It is worth noting that the space between the housing 100 and the flexible circuit board 200 is sealed with air. When the housing 100 is subjected to force, the air in the cavity of the housing 100 is squeezed. Since the cavity is a sealed structure, the air cannot be discharged from the cavity, so the air pressure in the cavity will continue to rise. On the one hand, the higher air pressure can produce a reaction force to the external force, preventing the external pressure from being too high and causing the housing 100 or the shielding structure 500 to directly press on the flexible circuit board 200, causing damage to the flexible circuit board 200. On the other hand, the reaction force caused by the pressure in the cavity is proportional to the external pressure, and the reaction force will only increase significantly when the external force is too large; in the early stage of external force pressing, the pressure in the cavity will not rise too high, and will not have a significant impact on the pressing feel.

[0042] It is easily understandable that the stiffness of the flexible three-dimensional force sensor can be adjusted by regulating the air pressure within the cavity: the more air is filled, the greater the air pressure within the cavity, and the higher the stiffness of the flexible three-dimensional force sensor; the less air is filled, the smaller the air pressure within the cavity, and the lower the stiffness of the flexible three-dimensional force sensor. Other types of gases, such as protective gases like helium, argon, or nitrogen, can also be filled within the cavity, which will not be elaborated herein.

[0043] When the outer shell 100 is deformed under an external force, it can drive the shielding structure 500 to extend between the light source 300 and the corresponding photosensitive sensor 400. The shielding structure 500 blocks the light path propagation to trigger the corresponding photosensitive sensor 400. When the outer shell 100 is squeezed, the shielding structure 500 descends together with the outer shell 100, thus extending between the light source 300 and the corresponding photosensitive sensor 400. The change in light intensity can cause the corresponding photosensitive sensor 400 to be triggered. By identifying which photosensitive sensor 400 is triggered, it is possible to determine in which direction the flexible three-dimensional force sensor is being exerted.

[0044] Moreover, when the outer shell 100 is further squeezed, the shielding structure 500 blocks the light path more severely, and the light intensity detected by the photosensitive sensor 400 becomes weaker. By detecting the intensity of the light, it is also possible to indirectly determine the magnitude of the external force currently acting on the outer shell 100, thereby enabling a comprehensive analysis of the direction and magnitude of the external force.

[0045] Furthermore, the outer shell 100 is an opaque silicone elastic shell. The opaque design is to avoid interference from external light on the photosensitive sensor 400. Specifically, the color of the outer shell 100 can be selected as black. The black outer shell can absorb more light, thereby further reducing the influence of external light on the photosensitive sensor 400.

[0046] Furthermore, ribs 110 are provided on the outer side of the outer shell 100. The ribs 110 are used to strengthen the structural strength of the outer shell 100, and the ribs 110 can also maintain the shape of the outer shell 100, preventing the outer shell 100 from undergoing material fatigue and shape deformation after multiple presses, and reducing the accuracy of three-dimensional force detection.

[0047] Furthermore, the shielding structure 500 is plate-shaped and horizontally placed between the light source 300 and the corresponding photosensitive sensor 400. The plate-shaped design enables the shielding structure 500 to achieve a better shielding effect. As for the specific shape of the shielding structure 500, it can be a square plate, a rectangular plate, or other types of plate shapes, which will not be elaborated herein.

[0048] Furthermore, the shielding area of the shielding structure 500 should be larger than the light path receiving area of the photosensitive sensor 400, so that the shielding structure 500 can completely block the light from the light source 300.

[0049] Further, regarding the specific setting method of the shielding structure 500, when the outer shell 100 is not subjected to an external force, the bottom of the shielding structure 500 and the top of the photosensitive sensor 400 are at the same height. Thus, when the outer shell 100 is subjected to an external force, the shielding structure 500 can immediately block the optical path emitted by the light source 300, and the triggering of the photosensitive sensor 400 is more timely, improving the sensitivity of this flexible three-dimensional force sensor and reducing the response time.

[0050] Further, the number of photosensitive sensors 400 and shielding structures 500 can be increased or decreased according to the actual situation. The more the number of photosensitive sensors 400 and shielding structures 500, the more external force directions can be detected; the fewer the number of photosensitive sensors 400 and shielding structures 500, the simpler the structure of this flexible three-dimensional force sensor and the lower the production cost. In this embodiment, the number of both the photosensitive sensors 400 and the shielding structures 500 is four, which can detect external forces in four different directions and can meet the requirements of three-dimensional force detection.

[0051] Further, the number of light sources 300 is at least two, and each light source 300 together forms a light-emitting array. By forming a light-emitting array, the illumination of the light source 300 in each direction can be made more uniform, avoiding detection deviations caused by differences in light intensity emitted in certain directions and affecting the detection accuracy of this flexible three-dimensional force sensor.

[0052] Specifically, the light source 300 is an infrared emitting diode with a wavelength of 940 nm and an emission angle of 140°. The photosensitive sensor 400 is an infrared photosensitive diode with a photosensitive wavelength range of 350 to 1120 nm and a receiving angle of 120°. The distance between the photosensitive sensor 400 and the light source 300 is 1.6 ± 0.15 mm, avoiding the situation where the distance between the photosensitive sensor 400 and the light source 300 is too large, resulting in too weak light intensity and the photosensitive sensor 400 being difficult to accurately identify the light intensity change; also avoiding the situation where the distance between the photosensitive sensor 400 and the light source 300 is too small, which is not conducive to the setting of the shielding structure 500 and will also increase the detection dead zone of the photosensitive sensor 400, causing the light intensity change to not be detected by the photosensitive sensor 400.

[0053] Next, performance testing is carried out on the flexible three-dimensional force sensor in this embodiment (this flexible three-dimensional force sensor uses four photosensitive sensors 400, which are respectively marked as S1, S2, S3, and S4), and the test results are as follows:

[0054] Refer to Figure 4 This flexible three-dimensional force sensor can detect a maximum normal force of up to 20 N. Moreover, through calculation, the hysteresis of the photosensitive sensor 400 is less than 10.5%, and the maximum sensitivity of the photosensitive sensor 400 can reach 2.88 V / N.

[0055] Reference Figure 5 The minimum detectable force of this flexible three-dimensional force sensor is 0.39 g (about 4 mN), that is, it has a resolution of 4 mN and can respond to micro forces.

[0056] Reference Figure 6 The response speed and recovery speed of this flexible three-dimensional force sensor are both relatively fast. The response time is about 22 ms and the recovery time is about 82 ms, which can meet the requirements of three-dimensional force detection.

[0057] The embodiments of the present application have been described in detail above in conjunction with the accompanying drawings. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present application. In addition, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

Claims

1. A flexible three-dimensional force sensor, characterized in that, Comprising: A housing, which is an elastic member, and the housing is in a hemispherical or semi-elliptical shape; A flexible circuit printed board, which is installed inside the housing, and a light source and a plurality of photosensitive sensors are installed on the flexible circuit printed board. The light source is located at the center of the housing, and each of the photosensitive sensors is distributed in a circumferential array around the light source; A shielding structure, the number of which is the same as the number of the photosensitive sensors. The shielding structure is arranged in one-to-one correspondence with the photosensitive sensors, and the shielding structure is installed on the inner wall of the housing; Wherein, the space between the housing and the flexible circuit printed board is sealed with air. When the housing is deformed under the influence of an external force, it can drive the shielding structure to extend between the light source and the corresponding photosensitive sensor, and the shielding structure blocks the optical path propagation to trigger the corresponding photosensitive sensor.

2. The flexible three-dimensional force sensor according to claim 1, characterized in that: The housing is an opaque silicone elastic shell.

3. The flexible three-dimensional force sensor according to claim 1, wherein: Ribs are arranged on the outer side of the housing, and the ribs are used to strengthen the structural strength of the housing.

4. The flexible three-dimensional force sensor according to claim 1, wherein: The shielding structure is in a plate shape and is horizontally arranged between the light source and the corresponding photosensitive sensor.

5. The flexible three-dimensional force sensor according to claim 4, wherein: When the housing is not affected by an external force, the bottom of the shielding structure and the top of the photosensitive sensor are at the same height.

6. The flexible three-dimensional force sensor according to claim 1, wherein: The number of both the photosensitive sensors and the shielding structures is four.

7. The flexible three-dimensional force sensor according to claim 1, wherein: The number of the light sources is at least two, and each of the light sources together constitutes a light-emitting array.

8. The flexible three-dimensional force sensor according to claim 1, wherein: The light source is an infrared emitting diode with a wavelength of 940 nm and an emission angle of 140°.

9. The flexible three-dimensional force sensor according to claim 1, wherein: The photosensitive sensor is an infrared photosensitive diode with a photosensitive wavelength range of 350 to 1120 nm and a receiving angle of 120°.

10. The flexible three-dimensional force sensor according to claim 1, wherein: The distance between the photosensitive sensor and the light source is 1.6 ± 0.15 mm.

Images