WO2023138281A1

WO2023138281A1 - Three-dimensional tactile sensor based on photosensitive element

Info

Publication number: WO2023138281A1
Application number: PCT/CN2022/140061
Authority: WO
Inventors: 易正琨; 尹猛; 黄滨华; 吴新宇
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2022-01-21
Filing date: 2022-12-19
Publication date: 2023-07-27
Also published as: CN114636503A

Abstract

A three-dimensional tactile sensor based on a photosensitive element, comprising a flexible sensor cover (1), a sensor circuit board (2), and a sensor base (3). The flexible sensor cover (1) is mounted on the sensor base (3); the flexible sensor cover (1) and the sensor base (3) enclose a closed space; the sensor circuit board (2) is mounted in the closed space; a light-emitting device (4) and a plurality of photosensitive elements (5, 6, 8, and 9) are provide on the flexible circuit board (2); light emitted by the light-emitting device (4) is reflected after reaching the inner wall of the flexible sensor cover (1); and the photosensitive elements (5, 6, 8, and 9) receive the light reflected by the inner wall of the flexible sensor cover (1). The three-dimensional tactile sensor based on the photosensitive element realizes monitoring and measurement of one-dimensional tactile and two-dimensional slippage, is easy to decouple tactile three-dimensional force, can realize estimation of different contact points at the same time, and can be widely used for robot tactile sensing.

Description

A 3D Tactile Sensor Based on Photosensitive Elements

technical field

The invention belongs to the technical field of sensors, and relates to a three-dimensional touch sensor based on a photosensitive element.

Background technique

Existing robots are already capable of performing various tasks such as walking or dancing. They can perform many tasks in well-modeled environments even without external sensory feedback. However, in unstructured environments, they must sense their surroundings and engage with various objects. The ultimate goal is to make robots capable of strong grasping and manipulation. To accomplish complex manipulation tasks, tactile information is essential. A robotic hand equipped with tactile sensors should be able to detect when contact occurs and recognize shape, object texture, force and sliding.

At present, common tactile sensors are mainly realized based on principles such as piezoresistive, piezoelectric, capacitive, triboelectric, and optical fibers. On the one hand, such schemes can only realize one-dimensional tactile pressure perception, and it is difficult to realize the other two-dimensional sliding sensation. On the other hand, the manufacture of each sensor involves material and process factors, and the preparation process is relatively complicated. Furthermore, the sensor is in direct contact with the object, and its wear and tear is inevitable after frequent use. After failure, it needs to be replaced with a new sensor, which will increase the cost.

technical problem

In order to overcome the problems existing in the above-mentioned prior art, the present invention proposes a three-dimensional tactile sensor based on photosensitive elements, which realizes the monitoring and measurement of one-dimensional tactile sensation and two-dimensional slip sensation, and is easy to realize the decoupling of three-dimensional tactile force, and at the same time realizes the estimation of different contact points, which can be widely used in robot tactile perception.

technical solution

The technical solution of the present invention to solve the above problems is: a three-dimensional tactile sensor based on photosensitive elements, which is special in that:

It includes a flexible sensor cover, a sensor circuit board and a sensor base; the flexible sensor cover is installed on the sensor base, and the flexible sensor cover and the sensor base form a closed space; the sensor circuit board is installed in the closed space;

A light-emitting device and several photosensitive elements are arranged on the sensor circuit board, the light emitted by the light-emitting device reaches the inner wall of the flexible sensor cover and is reflected, and the photosensitive element receives the light reflected by the inner wall of the flexible sensor cover.

When an external object touches the flexible sensor cover, the flexible sensor cover will deform due to its flexibility. After deformation, the path of the reflected light from the light-emitting device will change, the internal light field of the sensor will change, and the light intensity at different positions measured by the photosensitive element will also change. By monitoring the changes in the light intensity measurement value of the photosensitive element in real time, the calculation of the deformation of the flexible sensor cover can be realized, thereby realizing the monitoring of the external contact force.

Further, the sensor circuit board is embedded in the sensor base, and the upper surface of the sensor circuit board is flush with the upper surface of the sensor base.

Further, the flexible sensor cover includes a spherical structure, and the edges of the spherical structure extend horizontally to form a mounting plate, and the flexible sensor cover is detachably connected to the sensor base through the mounting plate.

Further, the lower surface of the above-mentioned mounting plate is bonded to the upper surface of the sensor base and the upper surface of the sensor circuit board; the bonding surface is coated with black glue to prevent external optics from entering the sensor.

The flexible sensor cover is directly in frequent contact with objects, and can be quickly replaced when the flexible sensor cover is damaged such as wear.

Further, the above-mentioned several photosensitive elements are arranged on the periphery of the light emitting device.

Further, one side of the sensor circuit board is provided with circuit board terminals.

Further, the upper part of the sensor base is provided with a groove, the sensor circuit board is embedded in the groove, the side of the sensor base is designed with a through hole, and the wire is connected to the circuit board terminal on the sensor circuit board through the through hole from the outside through the lower side of the groove.

Further, the mounting plate of the flexible sensor cover is mounted on the sensor base through screws.

Further, the above-mentioned light-emitting device is a light-emitting LED, and the photosensitive element can be a photoresistor, a photodiode, a phototransistor, etc., and the flexible sensor cover can be made of silica gel, or other elastic materials that are flexible and recoverable after being stressed. The sensor base can be made of resin or nylon material by 3D printing, or it can be made of other materials through different processes.

Further, the number of the above-mentioned photosensitive elements is four, and the four photosensitive elements are evenly distributed around the center of the circle with the light-emitting device as the center.

Beneficial effect

Compared with the prior art, the significant advantages of the three-dimensional tactile sensor based on the photosensitive element of the present invention are:

1) Applying light-emitting LEDs and photosensitive elements to tactile sensors can realize the monitoring and measurement of one-dimensional tactile sensation and two-dimensional sliding sensation, and it is easy to realize the decoupling of three-dimensional tactile force;

2) The sensor provided by the present invention can realize the estimation of different contact points at the same time;

3) The inner airtight space is formed by wrapping the flexible sensor cover and the sensor base, the flexible sensor cover directly contacts with the object frequently, the flexible sensor cover can be disassembled, and can be replaced quickly after wear and other damage;

4) The core part of the sensor is not in direct contact with the object, and the photosensitive element will not cause wear and tear failure;

5) By choosing chambers with different materials and wall thicknesses, the hardness can be changed to change the measurement range;

6) Compared with the existing tactile sensors, the sensor structure provided by the present invention is simple in design and easy to manufacture.

Description of drawings

Fig. 1 is a schematic diagram of axonometric view of a three-dimensional tactile sensor based on a photosensitive element provided by the present invention;

Fig. 2 is a schematic diagram of the assembled structure of Fig. 1;

Fig. 3 is a schematic structural diagram of the sensor circuit board in Fig. 2;

Fig. 4 is a schematic diagram of the measurement principle of the three-dimensional tactile sensor based on the photosensitive element provided by the present invention;

Fig. 5 is a schematic structural diagram of the sensor base in Fig. 2;

FIG. 6 is a schematic diagram of the structure of the sensor cavity in FIG. 2 .

Among them, 1. Flexible sensor cover, 2. Sensor circuit board, 3. Sensor base, 4. Light emitting device, 5. First photosensitive element, 6. Second photosensitive element, 7. Circuit board terminal, 8. Third photosensitive element, 9. Fourth photosensitive element.

Embodiments of the present invention

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the implementation manners in the present invention, all other implementation manners obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention.

1 and 2, the present invention provides a three-dimensional tactile sensor based on photosensitive elements, including a flexible sensor cover 1, a sensor circuit board 2 and a sensor base 3; the flexible sensor cover 1 is installed on the sensor base 3, and the flexible sensor cover 1 and the sensor base 3 form a closed space; the sensor circuit board 2 is installed in the closed space.

Preferably, the flexible sensor cover can be made of silicone material, or other elastic materials that are flexible and recoverable after being stressed.

Referring to FIG. 3 , the sensor circuit board 2 is provided with a light-emitting device 4 and several photosensitive elements. The light-emitting device is used to provide a light field. The light emitted by the light-emitting device 4 reaches the inner wall of the flexible sensor cover 1 and is reflected.

Referring to Fig. 4, when the flexible sensor cover 1 is deformed by force, the path of light reflected by the light-emitting device 4 will change, the internal light field of the sensor will change, and the light intensity at different positions measured by the photosensitive element will also change. By monitoring the changes in the light intensity measurement value of the photosensitive element in real time, the calculation of the deformation of the flexible sensor cover 1 is realized, thereby realizing the monitoring of the external contact force.

As a preferred embodiment of the present invention, the sensor circuit board 2 is embedded in the sensor base 3 , and the upper surface of the sensor circuit board 2 is flush with the upper surface of the sensor base 3 .

As a preferred embodiment of the present invention, the flexible sensor cover 1 includes a spherical structure, and the edges of the spherical structure extend horizontally to form a mounting plate, and the flexible sensor cover 1 is detachably connected to the sensor base 3 through the mounting plate.

As a preferred embodiment of the present invention, the lower surface of the mounting plate is bonded to the upper surface of the sensor base 3 and the upper surface of the sensor circuit board 2; the bonding surface is coated with black glue to prevent external optics from entering the sensor.

As a preferred embodiment of the present invention, the plurality of photosensitive elements are arranged on the periphery of the light-emitting device 4 , for example, with the light-emitting device 4 as the center of a circle, and evenly distributed around the circumference of the light-emitting device 4 .

As a preferred embodiment of the present invention, one side of the sensor circuit board 2 is provided with a circuit board terminal 7 . The upper part in the sensor base 3 is provided with a step-shaped groove, the sensor circuit board 2 is embedded in the groove, and the upper step supports it; the side of the sensor base 3 is designed with a through hole, and the groove at the corresponding through hole is deeper, and the wire is connected to the circuit board terminal 7 on the sensor circuit board 2 by the lower side of the groove from the outside through the through hole.

After the sensor circuit board 2 is embedded in the groove, there is still a gap between the bottom surface of the sensor circuit board 2 and the bottom surface of the groove (that is, the space surrounded by the lower steps in the groove) for heat dissipation of the sensor circuit board 2 .

As a preferred embodiment of the present invention, through holes are provided around the sensor base 3 , and the mounting plate of the flexible sensor cover 1 is mounted on the sensor base 3 by screws.

Preferably, the above-mentioned light-emitting device 4 is a light-emitting LED, and the photosensitive element can be a photoresistor, a photodiode, a phototransistor, etc. The flexible sensor cover 1 can be made of silica gel, or other elastic materials that are flexible and recoverable after being stressed. The sensor base 3 can be made of resin or nylon material by 3D printing, and can also be made of other materials through different processes.

Referring to FIG. 3 , as a preferred embodiment of the present invention, the number of the photosensitive elements is four, respectively: the first photosensitive element 5 , the second photosensitive element 6 , the third photosensitive element 8 , and the fourth photosensitive element 9 . The four photosensitive elements are evenly distributed around the circumference with the light emitting device 4 as the center.

Working principle of the present invention is:

Taking four photosensitive elements as an example, see Fig. 3 and Fig. 4, the light emitted by the light-emitting LED is reflected by the inner wall of the flexible sensor cover 1 to form a light field inside the sensor, and the first photosensitive element 5, the second photosensitive element 6, the third photosensitive element 8 and the fourth photosensitive element 9 respectively measure the light intensity at four different positions. When an external object touches the flexible sensor cover 1, the flexible sensor cover 1 will be deformed due to its flexibility. After deformation, the path of the reflected LED light will change, the internal light field of the sensor will change, and the light intensity at four different positions measured by the first photosensitive element 5, the second photosensitive element 6, the third photosensitive element 8 and the fourth photosensitive element 9 will also change. By monitoring the changes of the light intensity measurement values of the four photosensitive elements in real time, the calculation of the deformation of the flexible sensor cover 1 can be realized, thereby realizing the monitoring of the external contact force. Define S1 as the signal measured by the first photosensitive element 5, define S2 as the signal measured by the second photosensitive element 6, define S3 as the signal measured by the third photosensitive element 8, and define S4 as the signal measured by the fourth photosensitive element 9. Define the xyz coordinate direction as shown in Figure 1, where z is the direction perpendicular to the surface of the sensor. Define Sz as the tactile positive force, which can be understood as the magnitude of the applied force perpendicular to the direction of the sensor. Define Sx as the tangential sliding force in the x direction, which can be understood as the magnitude of the force applied in the x direction. Define Sy as the tangential sliding force in the y direction, which can be understood as the force applied in the y direction.

The positive tactile force can be calculated by the formula Sz=(k1*S1+k2*S2+k3*S3+k4*S4)/4 and Fz=a1*Sz ² +b1*Sz+c1, where k1, k2, k3, k4, a1, b1, and c1 are constant values obtained by calibration. The x-direction tangential sliding force can be calculated by the formula Sx=|k5*S1-k6*S3| and Fx=a2*Sx ² + b2*Sx+c2, where k5, k6, a2, b2, and c2 are constant values obtained by calibration. The tangential sliding force in the y direction can be calculated by the formula Sy=| k7*S2- k8*S4| and Fy=a3*Sy ² + b3*Sy+c3, where k7, k8, a3, b3, and c3 are constant values obtained by calibration.

Referring to Fig. 6, the flexible sensor cover 1 is a spherical structure, which is obtained by designing a circle with a radius R and a bias L, and its wall thickness is d. By choosing different materials and wall thickness d, its hardness can be changed, so as to realize the change of its measurement range.

Example

Referring to FIGS. 1-5 , a three-dimensional tactile sensor based on photosensitive elements includes a flexible sensor cover 1, a sensor circuit board 2 and a sensor base 3; the flexible sensor cover 1 is installed on the sensor base 3, and the flexible sensor cover 1 and the sensor base 3 form a closed space; the sensor circuit board 2 is installed in the closed space. The flexible sensor cover can be made of silicone material.

The sensor circuit board 2 is provided with a light-emitting device 4 and four photosensitive elements, the four photosensitive elements are respectively: a first photosensitive element 5 , a second photosensitive element 6 , a third photosensitive element 8 , and a fourth photosensitive element 9 . The four photosensitive elements are evenly distributed around the circumference with the light emitting device 4 as the center.

The light emitting device 4 is used to provide a light field, the light emitted by the light emitting device 4 reaches the inner wall of the flexible sensor cover 1 and then reflected, and the photosensitive element receives the light reflected by the inner wall of the flexible sensor cover 1 . Referring to Fig. 4, when the flexible sensor cover 1 is deformed by force, the path of light reflected by the light-emitting device 4 will change, the internal light field of the sensor will change, and the light intensity at different positions measured by the photosensitive element will also change. By monitoring the changes in the light intensity measurement value of the photosensitive element in real time, the calculation of the deformation of the flexible sensor cover 1 is realized, thereby realizing the monitoring of the external contact force.

The flexible sensor cover 1 includes a spherical structure, and the edges of the spherical structure extend horizontally to form a mounting plate. Through holes are provided around the sensor base 3 . The mounting plate of the flexible sensor cover 1 is mounted on the sensor base 3 by screws.

The sensor circuit board 2 is embedded in the sensor base 3 , and the upper surface of the sensor circuit board 2 is flush with the upper surface of the sensor base 3 . The lower surface of the mounting plate is bonded to the upper surface of the sensor base 3 and the upper surface of the sensor circuit board 2; the bonding surface is coated with black glue to prevent external optics from entering the sensor. One side of the sensor circuit board 2 is provided with a circuit board terminal 7 . The upper part in the sensor base 3 is provided with a step-shaped groove, the sensor circuit board 2 is embedded in the groove, and the upper step supports it; the side of the sensor base 3 is designed with a through hole, and the groove at the corresponding through hole is deeper, and the wire is connected to the circuit board terminal 7 on the sensor circuit board 2 by the lower side of the groove from the outside through the through hole. After the sensor circuit board 2 is embedded in the groove, there is still a gap between the bottom surface of the sensor circuit board 2 and the bottom surface of the groove (that is, the space surrounded by the lower steps in the groove) for heat dissipation of the sensor circuit board 2 . The light-emitting device 4 is a light-emitting led, and the photosensitive element is a photoresistor. The sensor base 3 is made by resin 3D printing.

In particular, this embodiment only provides a layout of four photosensitive elements, and a single photosensitive element, two photosensitive elements, and three photosensitive elements can also realize the measurement of contact force.

The invention applies the photosensitive element to the design of the robot's three-dimensional tactile sensor, realizes the monitoring and measurement of the one-dimensional tactile sense and the two-dimensional slippery sense, easily realizes the decoupling of the three-dimensional force of the tactile sense, and can realize the estimation of different contact points at the same time, and can be widely used in the tactile sense of robots. The inner airtight space is formed by wrapping the sensor cavity and the sensor base. The sensor cavity is in direct contact with objects frequently, and it is easy to replace by disassembling the sensor cavity, and can be quickly replaced after wear and other damage. The core part of the sensor is not directly in contact with the object and will not cause wear and tear failure. By choosing different materials and wall thicknesses, the hardness can be changed to achieve the change of the measurement range. Compared with the existing tactile sensor, the patented structure design is simple and easy to manufacture.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of protection of the present invention. Any equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related system fields, is also included in the scope of protection of the present invention.

Claims

A three-dimensional tactile sensor based on a photosensitive element, characterized in that:

It includes a flexible sensor cover (1), a sensor circuit board (2) and a sensor base (3); the flexible sensor cover (1) is installed on the sensor base (3), and the flexible sensor cover (1) and the sensor base (3) form a closed space; the sensor circuit board (2) is installed in the closed space;

The sensor circuit board (2) is provided with a light-emitting device (4) and several photosensitive elements, the light-emitting device (4) is used to provide a light field, the light emitted by the light-emitting device (4) reaches the inner wall of the flexible sensor cover (1) and then reflects, and the photosensitive element receives the light reflected by the inner wall of the flexible sensor cover (1);

After the flexible sensor cover (1) is deformed by force, the path of the light reflected by the light-emitting device (4) will change, the light field inside the sensor will change, and the light intensity at different positions measured by the photosensitive element will also change. By monitoring the change of the light intensity measurement value of the photosensitive element in real time, the calculation of the deformation of the flexible sensor cover (1) is realized, thereby realizing the monitoring of the external contact force.
A kind of three-dimensional tactile sensor based on photosensitive element according to claim 1, is characterized in that:

The sensor circuit board (2) is embedded in the sensor base (3), and the upper surface of the sensor circuit board (2) is flush with the upper surface of the sensor base (3).
A kind of three-dimensional tactile sensor based on photosensitive element according to claim 2, is characterized in that:

The flexible sensor cover (1) includes a spherical structure, the edges of which extend horizontally to form a mounting plate, and the flexible sensor cover (1) is detachably connected to the sensor base (3) through the mounting plate.
A kind of three-dimensional tactile sensor based on photosensitive element according to claim 3, is characterized in that:

The lower surface of the mounting plate is bonded to the upper surface of the sensor base (3) and the upper surface of the sensor circuit board (2); the bonding surface is coated with black glue to prevent external optics from entering the sensor.
A kind of three-dimensional tactile sensor based on photosensitive element according to claim 1, is characterized in that:

The several photosensitive elements are arranged on the periphery of the light emitting device (4).
A kind of three-dimensional tactile sensor based on photosensitive element according to claim 5, is characterized in that:

One side of the sensor circuit board (2) is provided with a circuit board terminal (7).
A three-dimensional tactile sensor based on photosensitive elements according to claim 6, characterized in that:

The upper part of the sensor base (3) is provided with a groove, the sensor circuit board (2) is embedded in the groove, the side of the sensor base (3) is designed with a through hole, and the wire is connected to the circuit board terminal (7) on the sensor circuit board (2) from the lower side of the groove after passing through the through hole from the outside.
A three-dimensional tactile sensor based on photosensitive elements according to claim 7, characterized in that:

The mounting plate of the flexible sensor cover (1) is mounted on the sensor base (3) through screws.
A three-dimensional tactile sensor based on photosensitive elements according to any one of claims 1-8, characterized in that:

The light-emitting device (4) is a light-emitting LED; the photosensitive element is a photoresistor, a photodiode or a phototransistor; the flexible sensor cover (1) is made of silica gel; the sensor base (3) is made of resin or nylon material by 3D printing.
A three-dimensional tactile sensor based on photosensitive elements according to claim 9, characterized in that:

The number of the photosensitive elements is four, and the four photosensitive elements are evenly distributed around the circle with the light emitting device (4) as the center.