Self-adaptive visual tactile sensor and adjusting method

Abstract

The invention discloses a self-adaptive visual tactile sensor and an adjusting method, the self-adaptive visual tactile sensor comprises a base and a shell, a control panel, a camera and at least one light source assembly are fixedly arranged on the base, a contact assembly is fixedly arranged at the upper end of the shell, and the self-adaptive visual tactile sensor is characterized in that a light source rotation driving mechanism is arranged on the base, and a liquid lens is fixedly arranged on the base; the liquid lens is located between the camera and the contact assembly, the center of the liquid lens and the optical axis of the camera are located on the same straight line, and the local focal length of the liquid lens and the included angle between the light source assembly and the horizontal plane can be automatically adjusted through electric signals sent by the contact assembly. The system has the advantages that imaging of the camera is clear, and the imaging quality is ensured; moreover, the camera achieves secondary focusing through the liquid lens, so that the camera does not need to adjust the position of the lens for imaging of different object distances, the focusing distance between the contact assembly and the camera is greatly shortened, and the overall size of the visual tactile sensor is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optical sensors, and in particular to an adaptive visual tactile sensor and an adjustment method. Background Art

[0002] As a new type of optical sensor, the visual tactile sensor is composed of a contact module, an illumination module, an image acquisition module and an information processing module, and shows great application potential in robot perception and operation tasks. The existing visual tactile sensor directly acquires images of the contact module through the image acquisition module. Since the image acquisition module requires a corresponding focusing distance, the size of the visual tactile sensor in the optical axis direction is large. Moreover, when the objects detected by the visual tactile sensor have different object distances, the image acquisition module needs to adjust the lens position, and these factors all lead to a large overall volume of the visual tactile sensor. In addition, the light parameters such as the light angle direction and color type output by the illumination module in the visual tactile sensor are fixed. When the touch range and object of the visual tactile sensor are different, there are technical problems with poor imaging effects in the images acquired by the image acquisition module, so improvement is needed. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an adaptive visual tactile sensor and an adjustment method, which greatly shorten the focusing distance of the visual tactile sensor to reduce the overall volume of the sensor, and at the same time improve the imaging quality better.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: an adaptive visual tactile sensor, including a base and a housing that are detachably fixed. A control board, a camera and at least one light source assembly are fixedly arranged on the base. A contact assembly is fixedly arranged at the upper end of the housing. A light source rotation driving mechanism is arranged on the base, and a liquid lens is fixedly arranged on the base. The liquid lens is located between the camera and the contact assembly, and the center of the liquid lens and the optical axis of the camera are on the same straight line. The contact assembly, the light source rotation driving mechanism and the liquid lens are all electrically connected to the control board. The local focal length of the liquid lens and the included angle between the light source assembly and the horizontal plane can be automatically adjusted through the electrical signal emitted by the contact assembly.

[0005] Further, 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 at the outermost layer of the entire contact assembly. The flexible pressure sensor is electrically connected to the control board.

[0006] Further, the flexible pressure sensor is a capacitive pressure sensor, including a plurality of electrode plates, which are laid on the upper and lower sides of the transparent elastomer in upper and lower layers, and the electrode plates in the upper and lower layers are vertically opposite to each other one by one.

[0007] Further, a plurality of electrodes are fixedly arranged on the lower surface of the liquid lens, dividing the lower surface of the liquid lens into a plurality of focusing regions, each electrode controlling one focusing region, and the reflected light generated in the contact region where each electrode plate in the contact assembly is located is projected onto the focusing region of the liquid lens, and the number of the focusing regions is equal to and corresponds one by one to the number of the electrode plates in the upper or lower layer in the contact assembly.

[0008] Further, the light source assembly is in three groups and is distributed along the circumferential direction of the liquid lens. The three groups of light source assemblies respectively emit red light, blue light and green light. The light source assembly includes an arc-shaped substrate and a light-emitting body fixed on the substrate.

[0009] Further, the light source rotation driving mechanism includes mounting columns at both ends of the substrate. The mounting columns are fixed on the base. A micro-motor is fixedly arranged at the upper end of the mounting column. The driving shaft of the micro-motor is fixed to the middle of the corresponding end of the substrate to drive the substrate to rotate, and the middle of the substrate is at the same height as the upper end surface of the liquid lens.

[0010] Further, the distance between the longitudinal center of the liquid lens and the lower end surface of the contact assembly is a first distance, and the distance between the longitudinal center of the liquid lens and the upper end surface of the camera is a second distance. The ratio of the first distance to 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: (1). Fix the adaptive visual tactile sensor on the robot arm. The robot arm drives the adaptive visual tactile sensor to make the contact assembly contact with an external object. The contact assembly is stressed and locally deformed, and the capacitive pressure sensor in the locally deformed area of the contact assembly 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 sent by the capacitive pressure sensor; (3). The control board adjusts the local focal length of the liquid lens according to the electrical signal sent by the capacitive pressure sensor, so that the images formed after the light rays reflected by the reflection layer in the contact assembly are focused by the liquid lens are on the same plane, so as to ensure the imaging quality of the camera.

[0012] Further, in the 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, adjust the angle between the substrate of the light source assembly and the horizontal plane to 0° - 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° - 80°.

[0013] Further, in the step (3), the adjustment of the local focal length of the liquid lens is achieved through the following relational expression: , , where: is the adjusted radius of curvature of the focusing area corresponding to the electrode sheet in the contact area that is compressed and deformed in the contact component in the liquid lens; n is the refractive index of the liquid lens; d 0 is the distance between the upper end surface of the contact component and the upper end surface of the liquid lens before the contact component contacts the external object; d i is the image distance of the liquid lens; is the compression amount of the stressed part on the contact component when the contact component contacts the external object; is the dielectric constant of the transparent elastomer; A is the area of a single electrode sheet in the capacitive pressure sensor; V is the output voltage between two vertically opposite electrode sheets in the contact area that is compressed and deformed in the contact component, is the distance between two vertically opposite electrode sheets, one on the upper layer and the other on the lower layer, in the contact component before the contact component contacts the external object; is the equivalent stiffness of the transparent elastomer.

[0014] Compared with the prior art, the advantages of the present invention are that a liquid lens is provided between the camera and the contact component, and the adaptive visual tactile sensor of the present invention can automatically adjust the local focal length of the liquid lens according to the electrical signal emitted by the contact component, making the imaging of the camera clear and ensuring the imaging quality; moreover, the camera realizes secondary focusing through the liquid lens, so that the camera does not need to adjust the lens position for imaging at different object distances, greatly shortening the spatial distance (i.e., the focusing distance) between the contact component and the camera, reducing the overall volume of the visual tactile sensor, and being applicable to more compact manipulators; in addition, the light source assembly can adjust the light angle according to the electrical signal emitted by the contact component to adapt to different touch scenarios, which further improves the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic external structure diagram of the present invention; Figure 2 A cross-sectional view of the present invention; Figure 3 A schematic diagram of the internal structure of the present invention after removing the housing; Figure 4 A schematic diagram of the light transmission of the present invention. Specific embodiments

[0016] The present invention will be further described in detail below in conjunction with the embodiments with reference to the drawings.

[0017] Embodiment 1: As Figures 1-3 shown, an adaptive visual tactile sensor includes a base 1 and a housing 2, which can be fixed to each other by screws or snaps. A control board 3, a camera 4, and three light source components 7 are fixedly arranged on the base 1. A contact component 5 is fixedly arranged at the upper end of the housing 2. The contact component 5 includes a transparent elastomer 51, a flexible pressure sensor 52, and a reflective layer 53. The material of the transparent elastomer 51 can be transparent silicone, transparent rubber, or other flexible transparent materials. The flexible pressure sensor 52 is fixed on the transparent elastomer 51. The flexible pressure sensor 52 is a capacitive pressure sensor, including a plurality of electrode plates (not shown in the figure). The electrode plates are laid flat on the upper and lower sides of the transparent elastomer 51 to form upper and lower layers, and the electrode plates in the upper and lower layers are vertically opposite to each other one by one. The reflective layer 53 is located at the uppermost layer of the entire contact component 5. The flexible pressure sensor 52 is electrically connected to the control board 3. A liquid lens 6 is fixedly arranged on the base 1. The liquid lens 6 is located between the camera 4 and the contact component 5, and the center of the liquid lens 6 and the optical axis of the camera 4 are 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 a 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 a second distance L2. The ratio of the first distance L1 to the second distance L2 is K, and 1 < K ≤ 1.5. A plurality of 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 a plurality of focusing regions. Each electrode controls one focusing region, and the reflected light generated by each contact region where each electrode plate in the contact component 5 is located is projected onto the focusing region of the liquid lens 6. The number of focusing regions is equal to and corresponds one by one to the number of electrode plates in the upper or lower layer in the contact component 5. The electrodes on the liquid lens 6 are electrically connected to the control board 3. When a certain contact region of the contact component 5 is deformed under pressure, the electrode plates in the deformed contact region output electrical signals, and the control board 3 adjusts the curvature of the focusing region on the liquid lens 6 corresponding to the electrode plates according to the electrical signals, that is, performs local focusing on the liquid lens; Three light source components 7 are distributed along the circumferential direction of the liquid lens 6. The three groups of 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 driving mechanism is provided on the base 1. The light source rotation driving mechanism includes mounting columns 8 located at both ends of the substrate 71. The mounting columns 8 are fixed on the base 1. A micro-motor 81 is fixedly provided at the upper end of the mounting column 8. The driving 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. And 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 sheet in the deformed contact area.

[0018] In the above-mentioned first embodiment, the light emitted by the light source component 7 is reflected after irradiating the reflective layer 53 of the contact component 5, and the reflected light enters the camera 4 after being refracted by the liquid lens 6, and finally the camera 4 forms an image.

[0019] Embodiment 2: An adjustment method for an adaptive visual and tactile sensor includes the following specific steps: (1). Fix the adaptive visual and tactile sensor on the robot arm. The robot arm drives the adaptive visual and tactile sensor to make the contact component 5 contact with an external object. The contact component 5 is deformed locally under pressure, and the capacitive pressure sensor (i.e., the electrode sheet) in the locally deformed area (i.e., the contact area where deformation occurs) of the contact component 5 sends an electrical signal to the control board 3; (2). The control board 3 controls 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 magnitude of the electrical signal sent by the capacitive pressure sensor, so that the light emitted by the light source component 7 can produce a strong reflection in the locally deformed area of the contact component 5 to improve the imaging clarity; the electrical signal sent 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° to 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° to 80°; (3). Then the control board 3 adjusts the local focal length of the liquid lens 6 according to the electrical signal sent by the capacitive pressure sensor, which is specifically realized through the following relational expressions: , , Where: is the adjusted radius of curvature of the focusing area corresponding to the electrode sheet in the contact area deformed under pressure in the contact component 5 in the liquid lens 6; n is the refractive index of the liquid lens 6; d 0 is the distance (i.e., object distance) between the upper end face of the contact component 5 and the upper end face of the liquid lens 6 before the contact component 5 contacts the external object; d i is the image distance of the liquid lens 6; is the compression amount of the stressed part on the contact component 5 when the contact component 5 contacts the external object; is the dielectric constant of the transparent elastomer 51; A is the area of a single electrode sheet in the capacitive pressure sensor; V is the output voltage between two vertically opposite electrode sheets in the contact area deformed under pressure in the contact component 5, is the distance between two vertically opposite electrode sheets in the upper and lower layers of the contact component before the contact component 5 contacts the external object; is the equivalent stiffness of the transparent elastomer 51; so that the image formed after the light reflected by the reflective layer 53 in the contact component 5 is focused by the liquid lens 6 is on the same plane S1, as Figure 4 shown, to ensure the imaging quality of the camera 4.

[0020] In step (3) of the above-mentioned second embodiment, the adjusted radius of curvature of the focusing area in the liquid lens 6 has the following derivation process: According to the lens imaging formula: , , where f is the focal length; It can be obtained that: ; When the thickness of the stressed deformation area on the contact component 5 is compressed after being squeezed, the distance between the upper end face of the stressed deformation area of the contact component 5 and the upper end face of the liquid lens 6 (i.e., the changed object distance) is: ; thus the adjusted focal length is: ; Finally, the adjusted radius of curvature of the focusing area in the liquid lens 6 is: .

[0021] The protection scope of the present invention includes but is not limited to the above embodiments, and its protection scope is subject to the claims. Any replacement, deformation, and improvement that are easily conceivable by those skilled in the art to this technology fall within the protection scope of the present invention.

Claims

1. An adaptive visual-tactile sensor, comprising a base and a housing that are detachably fixed. A control board, a camera, and at least one light source assembly are fixedly arranged on the base. A contact assembly is fixedly arranged at the upper end of the housing. It is characterized in that: A light source rotation driving mechanism is provided on the base, and a liquid lens is fixedly provided on the base. The liquid lens is located between the camera and the contact assembly, and the center of the liquid lens is on the same straight line as the optical axis of the camera. The contact assembly, the light source rotation driving 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 assembly and the horizontal plane can be automatically adjusted by the electrical signal emitted by the contact assembly.

2. The adaptive visual and tactile sensor according to claim 1, wherein: 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, and the reflective layer is located on the outermost layer of the entire contact assembly. The flexible pressure sensor is electrically connected to the control board.

3. The adaptive visual and tactile sensor according to claim 2, characterized in that: The flexible pressure sensor is a capacitive pressure sensor, including a plurality of electrode plates. The electrode plates are laid flat on the upper and lower sides of the transparent elastomer in upper and lower layers, and the electrode plates in the upper and lower layers are vertically opposite to each other one by one.

4. The adaptive visual tactile sensor according to claim 3, wherein: A plurality of electrodes are fixedly provided on the lower surface of the liquid lens, dividing the lower surface of the liquid lens into a plurality of focusing areas. Each electrode controls one focusing area. The reflected light generated in the contact area where each electrode plate 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 by one to the number of electrode plates in the upper or lower layer of the contact assembly.

5. The adaptive visual tactile sensor according to claim 1, wherein: The light source assembly is divided into three groups and is distributed along the circumferential direction of the liquid lens. The three groups of light source assemblies emit red light, blue light and green light respectively. The light source assembly includes an arc-shaped substrate and a light-emitting body fixed on the substrate.

6. The self-adaptive visual and tactile sensor according to claim 5, wherein: The light source rotation driving mechanism includes mounting posts 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 post. The driving shaft of the micro motor is fixed to the middle of the corresponding end of the substrate to drive the substrate to rotate, and the middle of the substrate is at the same height as the upper end surface of the liquid lens.

7. The adaptive visual tactile sensor according to claim 1, wherein: The distance between the longitudinal center of the liquid lens and the lower end surface of the contact assembly is the first distance, and the distance between the longitudinal center of the liquid lens and the upper end surface of the camera is the second distance. The ratio of the first distance to the second distance is K, and 1 < K ≤ 1.

5.

8. An adjustment method for an adaptive visual-tactile sensor, characterized in that It includes the following specific steps: (1), Fix the adaptive visual tactile sensor on the robot arm. The robot arm drives the adaptive visual tactile sensor to make the contact assembly contact with an external object. The contact assembly is deformed locally under pressure, and the capacitive pressure sensor in the locally deformed area of the contact assembly 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 sent by the capacitive pressure sensor, so that the images formed after the light reflected by the reflection layer in the contact component is focused by the liquid lens are on the same plane, so as to ensure the imaging quality of the camera.

9. The adjustment method of an adaptive visual-tactile sensor according to claim 8, characterized in that: In the step (2) described above, the electrical signal sent 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, adjust the angle between the substrate of the light source component 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 component and the horizontal plane to 60° to 80°.

10. The adjustment method of an adaptive visual-tactile sensor according to claim 8, characterized in that: In the step (3) described above, the adjustment of the local focal length of the liquid lens is achieved through the following relational expression: ， ， Wherein: is the adjusted radius of curvature of the focusing area corresponding to the electrode sheet in the contact area that is compressed and deformed in the contact component in the liquid lens; n is the refractive index of the liquid lens; d 0 is the distance between the upper end surface of the contact component and the upper end surface of the liquid lens before the contact component contacts the external object; d i is the image distance of the liquid lens; is the compression amount of the pressed part on the contact component when the contact component contacts the external object; is the dielectric constant of the transparent elastomer; A is the area of a single electrode sheet in the capacitive pressure sensor; V is the output voltage between two vertically opposite electrode sheets in the contact area that is compressed and deformed in the contact component, is the distance between two vertically opposite electrode sheets in the upper and lower layers of the contact component before the contact component contacts the external object; is the equivalent stiffness of the transparent elastomer.

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