Adaptive visual-tactile sensor and adjustment method

Abstract

The application discloses a kind of self-adapting visual tactile sensor and adjusting method, including base and shell, control panel is fixedly arranged on base, camera and at least one light source component, the upper end of shell is fixedly arranged with contact component, characterized in that base is provided with light source rotation drive mechanism, and base is fixedly arranged with liquid lens, liquid lens is located between camera and contact component, and the center of liquid lens and the optical axis of camera are located on the same straight line, the local focal length of liquid lens and the included angle between light source component and horizontal plane can be automatically adjusted by the electric signal emitted by contact component;Advantages are that the imaging of camera is clear, and the imaging quality is guaranteed;Moreover, the camera realizes secondary focusing through liquid lens, so that the camera does not need to adjust the lens position for different imaging distances, greatly shortens the focusing distance between contact component and camera, and reduces the overall volume of visual tactile sensor.

Description

Technical Field

[0001] This invention relates to the field of optical sensor technology, and in particular to an adaptive visual-tactile sensor and its adjustment method. Background Technology

[0002] As a novel type of optical sensor, the visual-tactile sensor comprises a contact module, an illumination module, an image acquisition module, and an information processing module, demonstrating significant application potential in robot perception and manipulation tasks. Existing visual-tactile sensors employ an image acquisition module that directly captures images from the contact module. Because the image acquisition module requires a corresponding focusing distance, the visual-tactile sensor has a large size along its optical axis. Furthermore, when the objects detected by the visual-tactile sensor have different object distances, the image acquisition module needs to adjust the lens position, all of which contribute to the overall large size of the sensor. In addition, the illumination module in the visual-tactile sensor outputs light with fixed angle, direction, and color parameters. When the touch range and object of the visual-tactile sensor vary, the images acquired by the image acquisition module suffer from poor imaging quality, thus requiring improvement. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an adaptive visual-tactile sensor and adjustment method, which greatly shortens the focusing distance of the visual-tactile sensor, thereby reducing the overall size of the sensor, while improving the imaging quality.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: an adaptive visual-tactile sensor, comprising a detachable and fixed base and a housing, wherein a control board, a camera, and at least one light source component are fixedly mounted on the base, a contact component is fixedly mounted on the upper end of the housing, a light source rotation drive mechanism is mounted on the base, and a liquid lens is fixedly mounted on the base, wherein the liquid lens is located between the camera and the contact component, and the center of the liquid lens is on the same straight line as the optical axis of the camera, wherein the contact component, the light source rotation drive mechanism, and the liquid lens are all electrically connected to the control board, and the local focal length of the liquid lens and the angle between the light source component and the horizontal plane can be automatically adjusted by the electrical signal emitted by the contact component.

[0005] Furthermore, the contact assembly includes a transparent elastomer, a flexible pressure sensor, and a reflective layer. The flexible pressure sensor is fixed on the transparent elastomer, the reflective layer is located on the top layer of the entire contact assembly, and the flexible pressure sensor is electrically connected to the control board.

[0006] Furthermore, the flexible pressure sensor is a capacitive pressure sensor, comprising multiple electrode plates. The electrode plates are laid flat on the upper and lower sides of the transparent elastic body in two layers, and the electrode plates in the upper and lower layers are aligned one-to-one.

[0007] Furthermore, multiple electrodes are fixedly disposed on the lower surface of the liquid lens, dividing the lower surface of the liquid lens into multiple focusing areas. Each electrode controls one focusing area. The reflected light generated by the contact area where each electrode sheet in the contact assembly is located is projected onto the focusing area of ​​the liquid lens, and the number of focusing areas is equal to and corresponds one-to-one with the number of electrode sheets located in the upper or lower layer of the contact assembly.

[0008] Furthermore, the light source components are in three groups and distributed along the circumference of the liquid lens. The three groups of light source components emit red light, blue light, and green light respectively. The light source components include an arc-shaped substrate and a light-emitting body fixed on the substrate.

[0009] Furthermore, the light source rotation drive mechanism includes mounting posts located at both ends of the substrate. The mounting posts are fixed on the base. A micro motor is fixedly provided at the upper end of the mounting posts. The drive shaft of the micro motor is fixed to the middle of the corresponding end of the substrate to drive the substrate to rotate. The middle of the substrate is at the same height as the upper surface of the liquid lens.

[0010] Furthermore, the distance between the longitudinal center of the liquid lens and the lower end face of the contact component is the first distance, and the distance between the longitudinal center of the liquid lens and the upper end face of the camera is the second distance. The ratio of the first distance and the second distance is K, and 1 < K ≤ 1.5.

[0011] An adjustment method for an adaptive visual-tactile sensor includes the following specific steps:

[0012] (1) The adaptive visual-tactile sensor is fixedly installed on the robotic arm. The robotic arm drives the adaptive visual-tactile sensor to make the contact component contact with the external object. The contact component is subjected to pressure and produces local deformation. The capacitive pressure sensor in the local deformation area of ​​the contact component sends an electrical signal to the control board.

[0013] (2) The control board controls the micro motor to adjust the angle between the substrate of the light source assembly and the horizontal plane according to the magnitude of the electrical signal emitted by the capacitive pressure sensor.

[0014] (3) The control board adjusts the local focal length of the liquid lens according to the electrical signal emitted by the capacitive pressure sensor, so that the light reflected by the reflective layer in the contact component and the image formed by the liquid lens after focusing are on the same plane, so as to ensure the imaging quality of the camera.

[0015] Furthermore, in step (2), the electrical signal emitted by the capacitive pressure sensor is a voltage value. The specific method for adjusting the angle between the substrate and the horizontal plane is as follows: when the voltage value is less than the set value, the angle between the substrate of the light source assembly and the horizontal plane is adjusted to 0° to 30°; when the voltage value is greater than or equal to the set value, the angle between the substrate of the light source assembly and the horizontal plane is adjusted to 60° to 80°.

[0016] Furthermore, in step (3), the adjustment of the local focal length of the liquid lens is achieved through the following relationship:

[0017] ,

[0018] ,

[0019] in: The radius of curvature of the focusing area corresponding to the electrode sheet in the contact area of ​​the contact assembly under pressure deformation in the liquid lens is adjusted; n is the refractive index of the liquid lens. d 0 The distance between the upper surface of the contact component and the upper surface of the liquid lens before the contact component comes into contact with an external object; d i The image distance of the liquid lens; This refers to the amount of compression at the pressure point on the contact component when it comes into contact with an external object. ρ is the dielectric constant of the transparent elastomer; A is the area of ​​a single electrode in the capacitive pressure sensor; V is the output voltage between two opposing electrodes in the pressure-deformed contact area of ​​the contact assembly. The distance between two opposing electrode plates located on the upper and lower layers of the contact assembly before the contact assembly comes into contact with an external object; It is the equivalent stiffness of a transparent elastomer.

[0020] Compared with the prior art, the advantages of this invention are that a liquid lens is disposed between the camera and the contact component, and the adaptive visual-touch sensor of this invention can automatically adjust the local focal length of the liquid lens according to the electrical signal emitted by the contact component, so that the camera image is clear and the image quality is guaranteed; moreover, the camera achieves secondary focusing through the liquid lens, so that the camera can image for different object distances without adjusting the lens position, which greatly shortens the spatial distance (i.e., focusing distance) between the contact component and the camera, reduces the overall size of the visual-touch sensor, and is suitable for smaller robotic arms; in addition, the light source component can adjust the angle of light according to the electrical signal emitted by the contact component to adapt to different touch scenarios, which further improves the image quality. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the external structure of the present invention;

[0022] Figure 2 This is a cross-sectional view of the present invention;

[0023] Figure 3 This is a schematic diagram of the internal structure of the present invention after the shell has been removed;

[0024] Figure 4 This is a schematic diagram of light transmission according to the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1: As Figure 1-3 As shown, an adaptive visual-tactile sensor includes a base 1 and a housing 2, which are fixed together by screws or clips. A control board 3, a camera 4, and three light source assemblies 7 are fixedly mounted on the base 1. A contact assembly 5 is fixedly mounted on the upper end of the housing 2. The contact assembly 5 includes a transparent elastomer 51, a flexible pressure sensor 52, and a reflective layer 53. The transparent elastomer 51 can be made of transparent silicone, transparent rubber, or other flexible transparent materials. The flexible pressure sensor 52 is fixed to the transparent elastomer 51 and is a capacitive pressure sensor, including multiple electrode plates (not shown in the figure). The electrode plates are laid flat on the upper and lower sides of the transparent elastomer 51 in two layers, with the electrode plates in the upper and lower layers corresponding to each other. The reflective layer 53 is located on the top layer of the entire contact assembly 5. The flexible pressure sensor 52 is electrically connected to the control board 3. A liquid lens 6 is fixedly mounted on the base 1, located between the camera 4 and the contact assembly 5, with the center of the liquid lens 6 aligned with the optical axis of the camera 4. Located on the same straight line, the distance between the longitudinal center of the liquid lens 6 and the lower end face of the contact component 5 is the first distance L1, and the distance between the longitudinal center of the liquid lens 6 and the upper end face of the camera 4 is the second distance L2. The ratio of the first distance L1 and the second distance L2 is K, and 1 < K ≤ 1.5. Multiple electrodes (not shown in the figure) are fixedly arranged on the lower surface of the liquid lens 6, dividing the lower surface of the liquid lens 6 into multiple focusing areas. Each electrode controls one focusing area, and the reflected light generated by the contact area where each electrode sheet in the contact component 5 is located is projected onto the focusing area of ​​the liquid lens 6. The number of focusing areas is equal to the number of electrode sheets located in the upper or lower layer of the contact component 5 and corresponds one-to-one. The electrodes on the liquid lens 6 are electrically connected to the control board 3. When a certain contact area of ​​the contact component 5 is deformed by pressure, the electrode sheet in the deformed contact area outputs an electrical signal. The control board 3 adjusts the curvature of the focusing area on the liquid lens 6 corresponding to the electrode sheet according to the electrical signal, that is, performs local focusing on the liquid lens.

[0027] Three light source components 7 are distributed along the circumference of the liquid lens 6. The three light source components 7 emit red light, blue light, and green light respectively. The light source component 7 includes an arc-shaped substrate 71 and a light-emitting body fixed on the substrate 71. The light-emitting body can be a point light source or a line light source. A light source rotation drive mechanism is provided on the base 1. The light source rotation drive mechanism includes mounting posts 8 located at both ends of the substrate 71. The mounting posts 8 are fixed on the base 1. A micro motor 81 is fixedly provided at the upper end of the mounting posts 8. The drive shaft of the micro motor 81 is fixed to the middle of the corresponding end of the substrate 71 to drive the substrate 71 to rotate. The middle of the substrate 71 is at the same height as the upper end surface of the liquid lens 6 to avoid forming a shadow area. The micro motor 81 is electrically connected to the control board 3. When a certain contact area of ​​the contact component 5 is deformed by pressure, the control board 3 can control the micro motor 81 to adjust the angle α between the substrate 71 of the light source component 7 and the horizontal plane according to the electrical signal output by the electrode in the deformed contact area.

[0028] In the first embodiment described above, the light emitted by the light source component 7 shines on the reflective layer 53 of the contact component 5 and is reflected. The reflected light is refracted by the liquid lens 6 and enters the camera 4, where the camera 4 finally forms an image.

[0029] Example 2: An adjustment method for an adaptive visual-tactile sensor, comprising the following specific steps:

[0030] (1) The adaptive visual-tactile sensor is fixedly installed on the robotic arm. The robotic arm drives the adaptive visual-tactile sensor to make the contact component 5 contact with the external object. The contact component 5 is subjected to pressure and undergoes local deformation. The capacitive pressure sensor (i.e., electrode plate) in the local deformation area of ​​the contact component 5 (i.e. the contact area where deformation occurs) sends an electrical signal to the control board 3.

[0031] (2) The control board 3 controls the micro motor 81 to adjust the angle α between the substrate 71 of the light source assembly 7 and the horizontal plane according to the magnitude of the electrical signal emitted by the capacitive pressure sensor, so that the light emitted by the light source assembly 7 can generate strong reflection in the local deformation area of ​​the contact assembly 5, thereby improving the clarity of the image; the electrical signal emitted by the capacitive pressure sensor is a voltage value, specifically: when the voltage value is less than the set value, the micro motor 81 drives the substrate 71 to rotate, so that the angle α between the substrate 71 and the horizontal plane is 0°~30°; when the voltage value is greater than or equal to the set value, the angle α between the substrate 71 and the horizontal plane is adjusted to 60°~80°;

[0032] (3) Then, the control board 3 adjusts the local focal length of the liquid lens 6 according to the electrical signal emitted by the capacitive pressure sensor, specifically through the following relationship:

[0033] ,

[0034] ,

[0035] in: is the radius of curvature of the focusing area corresponding to the electrode sheet in the contact area of ​​the liquid lens 6 and the contact assembly 5 under pressure deformation after adjustment; n is the refractive index of the liquid lens 6. d 0 The distance (i.e., object distance) between the upper end surface of the contact component 5 and the upper end surface of the liquid lens 6 before the contact component 5 comes into contact with an external object. d i The image distance of the liquid lens 6; This refers to the amount of compression of the pressure-bearing portion of the contact component 5 when it comes into contact with an external object. denoted as ρ, where ρ is the dielectric constant of the transparent elastomer 51; A is the area of ​​a single electrode in the capacitive pressure sensor; V is the output voltage between two opposing electrodes within the pressure-deformed contact area of ​​the contact assembly 5. The distance between two opposing electrode plates located on the upper and lower layers of the contact assembly before the contact assembly 5 comes into contact with an external object; It is the equivalent stiffness of the transparent elastomer 51; ensuring that the image formed by the light reflected by the reflective layer 53 in the contact component 5 and focused by the liquid lens 6 is on the same plane S1, such as... Figure 4 As shown, this is to ensure the imaging quality of camera 4.

[0036] In step (3) of the above embodiment 2, the radius of curvature of the focusing area in the liquid lens 6 after adjustment The derivation process is as follows:

[0037] According to the lens imaging formula: , , where f is the focal length;

[0038] available: ;

[0039] When the pressure-deformed area on contact component 5 is compressed, the thickness is reduced. Then, the distance between the upper end surface of the pressure-deformed area of ​​the contact component 5 and the upper end surface of the liquid lens 6 (i.e., the changed object distance) is increased. for: ; thus making the adjusted focal length for: ;

[0040] Finally, the radius of curvature of the focusing area in liquid lens 6 after adjustment was obtained. for: .

[0041] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. An adaptive visual-tactile sensor, comprising a detachably fixed base and a housing, wherein a control board, a camera, and at least one light source assembly are fixedly mounted on the base, and a contact assembly is fixedly mounted on the upper end of the housing, characterized in that: The base is provided with a light source rotation drive mechanism, and a liquid lens is fixedly mounted on the base. The liquid lens is located between the camera and the contact component, and the center of the liquid lens is on the same straight line as the optical axis of the camera. The contact component, the light source rotation drive mechanism and the liquid lens are all electrically connected to the control board. The local focal length of the liquid lens and the angle between the light source component and the horizontal plane can be automatically adjusted by the electrical signal emitted by the contact component. The contact assembly includes a transparent elastomer, a flexible pressure sensor, and a reflective layer. The flexible pressure sensor is fixed to the transparent elastomer, and the reflective layer is located on the top layer of the entire contact assembly. The flexible pressure sensor is electrically connected to the control board.

2. The adaptive visual-tactile sensor as described in claim 1, characterized in that: The flexible pressure sensor is a capacitive pressure sensor, comprising multiple electrode plates. The electrode plates are laid flat on the upper and lower sides of the transparent elastic body in two layers, with the electrode plates in the upper and lower layers facing each other one-to-one.

3. The adaptive visual-tactile sensor as described in claim 2, characterized in that: The liquid lens has multiple electrodes fixedly disposed on its lower surface, dividing the lower surface of the liquid lens into multiple focusing areas. Each electrode controls one focusing area. The reflected light generated by the contact area where each electrode sheet in the contact assembly is located is projected onto the focusing area of ​​the liquid lens. The number of focusing areas is equal to the number of electrode sheets located in the upper or lower layer of the contact assembly and corresponds one-to-one.

4. The adaptive visual-tactile sensor as described in claim 1, characterized in that: The light source components are in three groups and distributed along the circumference of the liquid lens. The three groups of light source components emit red light, blue light and green light respectively. The light source components include an arc-shaped substrate and a light-emitting body fixed on the substrate.

5. An adaptive visual-tactile sensor as described in claim 4, characterized in that: The light source rotation drive mechanism includes mounting posts located at both ends of the substrate. The mounting posts are fixed on the base. A micro motor is fixedly provided at the upper end of the mounting posts. The drive shaft of the micro motor is fixed to the middle of the corresponding end of the substrate to drive the substrate to rotate. The middle of the substrate is at the same height as the upper surface of the liquid lens.

6. An adaptive visual-tactile sensor as described in claim 1, characterized in that: The distance between the longitudinal center of the liquid lens and the lower end face of the contact component is the first distance, and the distance between the longitudinal center of the liquid lens and the upper end face of the camera is the second distance. The ratio of the first distance and the second distance is K, and 1 < K ≤ 1.

5.

7. A method for adjusting an adaptive visual-tactile sensor, characterized in that... The specific steps include the following: (1) The adaptive visual-tactile sensor is fixedly installed on the robotic arm. The robotic arm drives the adaptive visual-tactile sensor to make the contact component contact with the external object. The contact component is subjected to pressure and produces local deformation. The capacitive pressure sensor in the local deformation area of ​​the contact component sends an electrical signal to the control board. (2) The control board controls the micro motor to adjust the angle between the substrate of the light source assembly and the horizontal plane according to the magnitude of the electrical signal emitted by the capacitive pressure sensor. (3) The control board adjusts the local focal length of the liquid lens according to the electrical signal emitted by the capacitive pressure sensor, so that the light reflected by the reflective layer in the contact component and the image formed by the liquid lens after focusing are on the same plane, so as to ensure the imaging quality of the camera.

8. The adjustment method for an adaptive visual-tactile sensor as described in claim 7, characterized in that: In step (2), the electrical signal emitted by the capacitive pressure sensor is a voltage value. The specific adjustment method for the angle between the substrate and the horizontal plane is as follows: when the voltage value is less than the set value, adjust the angle between the substrate of the light source assembly and the horizontal plane to 0° to 30°; when the voltage value is greater than or equal to the set value, adjust the angle between the substrate of the light source assembly and the horizontal plane to 60° to 80°.

9. The adjustment method for an adaptive visual-tactile sensor as described in claim 7, characterized in that: In step (3), the adjustment of the local focal length of the liquid lens is achieved through the following relationship: ， ， in: d0 is the radius of curvature of the focusing area corresponding to the electrode plate in the contact region of the liquid lens and the contact assembly under pressure deformation; n is the refractive index of the liquid lens; d0 is the distance between the upper surface of the contact assembly and the upper surface of the liquid lens before the contact assembly comes into contact with the external object; d0 is the distance between the upper surface of the contact assembly and the upper surface of the liquid lens. i The image distance of the liquid lens; This refers to the amount of compression at the pressure point on the contact component when it comes into contact with an external object. ρ is the dielectric constant of the transparent elastomer; A is the area of ​​a single electrode in the capacitive pressure sensor; V is the output voltage between two opposing electrodes in the pressure-deformed contact area of ​​the contact assembly. The distance between two opposing electrode plates located on the upper and lower layers of the contact assembly before the contact assembly comes into contact with an external object; It is the equivalent stiffness of a transparent elastomer.

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