Sensor for transmitting finger operation in VR equipment

Abstract

The invention provides a sensor for transmitting finger operation in VR (virtual reality) equipment. The sensor consists of a four-component force sensor and a force transmission structure, wherein the four-component force sensor is provided with four varistors which are separated from one another and do not have crosstalk; the force transmission structure is provided with a rigid lining; the inner layer and the outer layer of the structure are tightly attached, the outer layer is a soft hemispherical shell, and the middle is a hard structure similar to a four-corner supporting frame. The force conduction structure is tightly connected with the upper packaging layer of the four-component force sensor through a bonding layer; a set of equipment used for collecting and sending sensor signals can realize remote data transmission through a carried Bluetooth signal sending module; therefore, compared with a traditional flexible shear force sensor, the sensor provided by the invention can realize higher-dimension shear force sensing, not only can sense the magnitude of the shear force, but also has full-angle identification capability on the direction of the shear force.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and in particular relates to a sensor for transmitting finger operations in VR equipment. Background Art

[0002] With the progress and development of science and technology, people's living standards are constantly improving. The traditional human-computer interaction mode, the display with keyboard, mouse, and handle, can no longer meet the needs of a more three-dimensional and immersive interaction mode. The new generation of human-computer interaction interface has first evolved virtual reality technology (VR) and augmented reality technology (AR). The emergence of VR glasses has revolutionized the flat display mode and brought it to our eyes, realizing a visual immersive experience, and taking a big step towards a fully immersive human-computer interaction experience. However, the interaction mode of the VR glasses currently on the market is basically achieved through the operation handle. Although the VR handle can accurately complete the user's various instructions and contains many buttons and functions, most of these handles are very heavy. In addition, the operation mode of the joystick is undoubtedly a great impact on the user's immersive experience. In addition, there are also some interaction solutions using smart gloves on the market. Sensors at the joints and wrists are used to monitor the posture and position of the human hand, and the interaction with the machine terminal is achieved through the hand posture. This type of smart glove device makes people's operation in the VR device more immersive, but there is also the problem that the device is heavy and will cause fatigue after wearing it for a long time. Therefore, it is necessary to develop a lightweight, small, and high-performance VR interaction mode.

[0003] Flexible tactile sensors, also known as electronic skin, are thin and light, have low detection limits, high sensitivity, and are highly flexible. They can be well attached to human skin, deform with human movement, and maintain stable performance. They have been widely used in medical health testing and human-computer interaction. However, current research on flexible tactile sensors mainly focuses on the perception of normal stress, and various methods of introducing microstructures are often used to improve sensor sensitivity. In addition, the sensing of shear force is also a major function of tactile receptors. The commonly used method is to use force-conducting structures, such as domes, assembled on the surface of the sensor, and convert the shear force exerted on the device into the normal force of the pressure sensor, thereby realizing the perception of shear force. Although many studies have been able to sense shear force, the simultaneous high-precision recognition of the direction and magnitude of the shear force is still a major problem in the field of flexible tactile sensors. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a sensor for transmitting finger operations in VR devices, which can realize full-angle force recognition and perfectly reproduce the user's operation instructions.

[0005] A sensor for transmitting finger operations in VR equipment, comprising a force conduction structure, a four-component force sensor component, a voltage-dividing resistor component, a collection module, and a processing module;

[0006] The four-component force sensor assembly is composed of an upper packaging layer 3, an upper electrode layer 4, a piezoresistor layer 5, a lower electrode layer 6 and a lower packaging layer 7 from top to bottom; wherein the upper electrode layer 4 is composed of four separate sector-shaped electrodes that can be combined into a full circle, and the lower electrode layer 6 is a complete circular electrode, thereby dividing the piezoresistor layer 5 located between the upper electrode layer 4 and the lower electrode layer 6 into four varistors;

[0007] The voltage-dividing resistor assembly is composed of four fixed resistors with the same resistance value, and one end of each fixed resistor is connected in series with a sector electrode, and the other end is connected to a common ground terminal;

[0008] The force conduction structure is composed of a flexible micro-dome shell 1 and a rigid lining structure 2; wherein the rigid lining structure 2 has four branches distributed in a cross shape, and each branch is bonded to the upper packaging layer 3, and at the same time, the projection of each branch on the upper packaging layer 3 corresponds to the projection of each sector electrode on the upper packaging layer 3; the rigid lining structure 2 is used to transfer the pressure exerted on the flexible micro-dome shell 1 to each varistor;

[0009] When measuring the pressure on the flexible micro-dome housing 1, a constant voltage is applied to the lower electrode layer 6, and the divided voltage of the four fixed resistors is measured by the acquisition module, wherein the pressure component borne by each piezoresistor is different, and the divided voltage of the corresponding fixed resistor is different;

[0010] The processing module determines the type and magnitude of the pressure according to the change directions and magnitudes of the four partial pressures, wherein the types of pressure are shear force and normal force.

[0011] Furthermore, the method for determining the type of pressure to which the flexible micro-dome housing 1 is subjected is as follows:

[0012] It is determined whether the changing directions of the four partial pressures are the same. If yes, the pressure on the flexible micro-dome shell 1 is a normal force. If no, the pressure on the flexible micro-dome shell 1 is a shear force. The changing direction includes increasing and decreasing.

[0013] Furthermore, the method for determining the pressure on the flexible micro-dome housing 1 is as follows:

[0014] The four divided voltages corresponding to the four sector electrodes are recorded as VIO0, VIO1, VIO2, and VIO3 in a clockwise direction;

[0015] Determine whether the change directions of the four partial pressures are the same. If yes, the pressure on the flexible micro-dome housing 1 is the normal force, and the sum of VIO0, VIO1, VIO2, and VIO3 is used as the magnitude of the normal force on the flexible micro-dome housing 1; wherein the change direction includes increase and decrease;

[0016] If not, the pressure on the flexible micro-dome shell 1 is a shear force, VIO0 and VIO2 are used as the X component of the shear force vector, VIO1-VIO3 are used as the Y component of the shear force vector, and at the same time, the magnitude of the resultant vector of the X component and the Y component in the rectangular coordinate system is used as the magnitude of the shear force on the flexible micro-dome shell 1, and the direction of the resultant vector is used as the direction of the shear force on the flexible micro-dome shell 1.

[0017] Furthermore, the material of the upper encapsulation layer 3 and the lower encapsulation layer 7 is polyimide PI.

[0018] Furthermore, the material of the upper electrode layer 4 and the lower electrode layer 6 is conductive silver paste.

[0019] Furthermore, the radius of the full circle formed by the upper electrode layer 4 is smaller than the radius of the circular electrode of the lower electrode layer 6 .

[0020] Furthermore, the preparation method of the force conduction structure is:

[0021] 1) Use a melt extrusion 3D printer to print two PLA plastic molds, one of which has a hemispherical groove with a radius of 3 mm, and the other has a cylindrical protrusion with four triangular support structures;

[0022] 2) Weigh and mix the PDMS matrix and the cross-linking agent in a ratio of 10:1 on an electronic scale, stir with a glass rod until fully mixed, pour the PDMS mixture into a PLA plastic mold, perform vacuum defoaming twice in a vacuum defoaming box, and then heat the PLA plastic mold on a hot plate at 85°C for 2 hours;

[0023] 3) Peel off the raised PLA plastic mold on the solidified PDMS. At this time, there will be a pit on the flat side of the PDMS reserved for the rigid lining structure. Then weigh and mix the epoxy resin A and B components in a 1:1 ratio on an electronic scale, stir with a glass rod until fully mixed, pour the epoxy resin mixture into the pit of the PDMS, and then use a vacuum defoaming box to perform vacuum defoaming twice, and keep the PDMS at room temperature for 24 hours;

[0024] 4) The cured epoxy resin and PDMS are peeled off on the other side of the mold, and the excess part is removed with a blade, leaving the hemispherical dome and the flat side to obtain a force conduction structure with a rigid lining.

[0025] Furthermore, the preparation method of the four-component force sensor assembly is:

[0026] 1) After wiping both sides of the varistor clean with anhydrous ethanol, use two pieces of 240-grit sandpaper as a template, clamp them on both sides of the varistor, and use a hot press to heat press at 50°C for 90 seconds;

[0027] 2) After the hot pressing is completed, the varistor sheet is cut into discs with a radius of 4 mm using a laser marking machine;

[0028] 3) Using a paste printer, a silver paste material is used to print the upper electrode, the lower electrode and their leads on the adhesive side of a single-sided PI tape with a thickness of 100 microns, wherein the upper electrode is four separate sectors and the lower electrode is a whole circular piece;

[0029] 4) After printing, place the PI tape on a hot plate at 105°C and heat for 5 minutes;

[0030] 5) After the silver paste material is cured, place the PI tape with the upper electrode layer with the non-adhesive side facing upward into a plasma treatment machine and perform plasma treatment for 5 minutes to make the surface hydrophilic;

[0031] 6) The two prepared PI tapes with the upper electrode and the lower electrode are stacked and assembled with the varistor sheet to obtain a four-component force sensor assembly.

[0032] Furthermore, the assembly method of the four-component force sensor assembly and the force transmission structure is as follows:

[0033] 1) Weigh and mix the PDMS substrate and the cross-linking agent in a ratio of 10:1 on an electronic scale, stir the mixture with a glass rod until it is fully mixed, and then use a vacuum defoaming box to perform vacuum defoaming twice to remove excess air in the PDMS for later use;

[0034] 2) Applying the mixed, stirred and defoamed PDMS on the upper side of the upper packaging layer of the four-component force sensor assembly, and then aligning the prepared force conduction structure with a rigid liner and adhering it to the upper side of the upper packaging layer of the four-component force sensor assembly, wherein the four branches of the rigid liner structure are aligned one by one with the four separated sector-shaped electrodes of the upper electrode layer;

[0035] 3) After alignment and adhesion, the adhered device is placed on a 45° C. hot stage for 12 hours to complete the assembly of the four-component force sensor assembly and the force conduction structure.

[0036] Furthermore, the acquisition module packages the four collected partial pressures and sends them to the VR terminal where the processing module is located through serial communication, and the processing module determines the type and size of the pressure, thereby controlling the cursor in the VR virtual reality to move in the direction of the shear force, and finally realizing the cursor clicking and simulated key input in the VR virtual reality.

[0037] Beneficial effects:

[0038] 1. The present invention provides a sensor for transmitting finger operations in VR devices, which is composed of a four-component force sensor with four mutually separated and non-crosstalking piezoresistors and a force conduction structure with a rigid lining; the inner and outer layers of the structure are tightly fitted, the outer layer is a soft hemispherical shell, and the middle layer is a hard structure similar to a four-corner support frame; the force conduction structure is tightly connected to the packaging layer on the above-mentioned four-component force sensor through an adhesive layer; a set of equipment for sensor signal collection and transmission can realize remote data transmission through a Bluetooth signal transmission module; therefore, compared with traditional flexible shear force sensors, the sensor of the present invention can realize higher-dimensional shear force perception, not only can it perceive the size of the shear force, but also has the ability to recognize the direction of the shear force at all angles.

[0039] 2. The present invention provides a sensor for transmitting finger operations in VR devices. Multiple piezoresistor sensing modules are formed in a small area through a circuit connection method of a complete lower electrode and multiple fan-shaped upper electrodes. Each piezoresistor is then connected in series with a resistor of a fixed resistance. The divided voltage on the fixed resistor is collected to simultaneously obtain the resistance value of each piezoresistor, and then the components of the shear force relative to each direction are obtained, thereby achieving accurate judgment of the direction and magnitude of the shear force.

[0040] 3. The present invention provides a sensor for transmitting finger operations in VR devices. By introducing a hard rigid lining into the force conduction structure, the efficiency of shear force conduction is greatly improved. When the same shear force is applied, a greater positive pressure can be generated on the lower surface of the structure. After being bonded to the four-component force sensor device through an adhesive layer, the sensitivity of shear force recognition is greatly improved, so that the invention can not only identify the direction of shear force in all directions, but also detect the magnitude of shear force.

[0041] 4. The present invention provides a sensor for transmitting finger operations in VR devices. By attaching multiple small flexible omnidirectional force recognition sensors to the fingers, the user can perform a series of operations by just moving the fingers slightly when performing VR interaction. In addition, the sensor is small, flexible and lightweight, and will not put too much burden on the user's hands. It will not cause fatigue after long-term use, and a more immersive experience can be achieved during VR interaction. In other words, the present invention can transmit data to the VR terminal through a single-chip microcomputer to realize operations such as cursor movement, clicking, and button simulation within the application.

[0042] 5. The present invention provides a sensor for transmitting finger operations in VR devices. The packaging layer PI, the outer layer PDMS of the force conduction structure, and the pressure sensitive layer used in the flexible omnidirectional force sensor are all flexible materials, and all have good biocompatibility and can be worn on the human body for a long time. Compared with traditional rigid omnidirectional force sensors, the present invention has the advantages of lower cost, clear structure, and simple preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the split structure of the flexible omnidirectional force recognition sensor of the present invention;

[0044] Figure 2 It is a schematic diagram of the connection between the flexible omnidirectional force recognition sensor of the present invention and the single-chip microcomputer;

[0045] Figure 3 This is a graph of current changes after the piezoresistive sheet of the flexible omnidirectional force recognition sensor of the present invention is subjected to 14,000 cycles of compression and recovery under a normal force of 41 kPa after the microstructure is introduced;

[0046] Among them, 1-PDMS flexible micro-dome shell, 2-rigid inner lining epoxy resin structure, 3-polyimide PI upper packaging layer, 4-silver paste upper electrode layer, 5-varistor sheet, 6-silver paste lower electrode layer, 7-polyimide PI lower packaging layer, 8-P-103 potentiometer, 9-equivalent resistance of four varistors, 10-STM32 microcontroller. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0048] like Figure 1 As shown, a sensor for transmitting finger operation in a VR device includes a force conduction structure, a four-component force sensor component, a voltage divider resistor component, a collection module, and a processing module;

[0049] The four-component force sensor assembly comprises, from top to bottom, an upper packaging layer (3), an upper electrode layer (4), a piezoresistor layer (5), a lower electrode layer (6) and a lower packaging layer (7); wherein the upper electrode layer (4) is composed of four separate sector-shaped electrodes that can be combined into a full circle, and the lower electrode layer (6) is a complete circular electrode, thereby dividing the piezoresistor layer (5) located between the upper electrode layer (4) and the lower electrode layer (6) into four non-interfering piezoresistors for separately responding to the normal pressure and tangential pressure applied to each upper sector-shaped electrode; it should be noted that the force conduction structure and the four-component force sensor device are stacked on the upper packaging layer 3 through an adhesive layer to form the flexible omnidirectional force recognition sensor of the present invention, and each part of the entire device cannot be displaced, but because each part is made of flexible material and the overall thickness of the device is very thin, the sensor still has good bending ability when used.

[0050] The voltage-dividing resistor assembly is composed of four fixed resistors with the same resistance value, and one end of each fixed resistor is connected in series with a sector electrode, and the other end is connected to a common ground terminal;

[0051] The force transmission structure is composed of a flexible micro-dome outer shell (1) and a rigid lining structure (2); wherein the rigid lining structure (2) has four branches distributed in a cross shape, and each branch is bonded to the upper packaging layer (3), and at the same time, the projection of each branch on the upper packaging layer (3) corresponds one-to-one with the projection of each fan-shaped electrode on the upper packaging layer (3); the rigid lining structure (2) is used to transmit the pressure exerted on the flexible micro-dome outer shell (1) to each varistor; wherein the radius of the whole circle formed by the upper electrode layer (4) is slightly smaller than the radius of the circular electrode of the lower electrode layer (6), and each electrode is provided with a lead wire to lead out the electrode.

[0052] When measuring the pressure on the flexible micro-dome housing (1), a constant voltage is applied to the lower electrode layer (6), and the divided voltage of four fixed resistors is measured through the acquisition module, wherein the pressure components borne by each piezoresistor are different, and the divided voltage of the corresponding fixed resistor is different; that is, by measuring the divided voltage of the fixed resistor, the resistance change of the piezoresistors in the corresponding area can be obtained.

[0053] The processing module determines the type and magnitude of the pressure according to the change directions and magnitudes of the four partial pressures, wherein the types of pressure are shear force and normal force.

[0054] It should be noted that the force conduction structure is a "quadrangle" structure similar to a camera tripod. When the upper end of the structure is subjected to a lateral shear force, the bottom area consistent with the direction of the shear force will be subjected to a greater positive pressure to maintain the stability of the overall structure. Therefore, the role of this structure is to convert the shear force exerted on the device into the positive pressure exerted on each area of ​​the four-component force device. The introduction of the rigid lining structure 2 greatly improves the accuracy and efficiency of shear force conduction. Here, the discussion is based on the assumption that the device has been subjected to a certain normal pressure. When the device is subjected to a shear force in a certain direction, the positive pressure exerted on the area corresponding to the direction will increase, and the two sides will hardly bear the additional positive pressure brought by the shear force, while the positive pressure exerted in the opposite direction will decrease. This is the role of the force conduction structure.

[0055] Based on this, the method for determining the pressure category to which the flexible micro-dome housing (1) is subjected is as follows:

[0056] It is determined whether the directions of change of the four partial pressures are the same. If so, the pressure on the flexible micro-dome shell (1) is a normal force; if not, the pressure on the flexible micro-dome shell (1) is a shear force, wherein the direction of change includes increase and decrease.

[0057] The method for determining the magnitude of the pressure on the flexible micro-dome housing (1) is as follows:

[0058] The four partial pressures corresponding to the four sector electrodes are recorded as VIO0, VIO1, VIO2, and VIO3 in a clockwise direction; it is determined whether the directions of change of the four partial pressures are the same; if so, the pressure on the flexible micro-dome shell (1) is a normal force, and the sum of VIO0, VIO1, VIO2, and VIO3 is used as the magnitude of the normal force on the flexible micro-dome shell (1); wherein the direction of change includes increase and decrease; if not, the pressure on the flexible micro-dome shell (1) is a shear force, and VIO0 and VIO2 are used as the X components of the shear force vector, and VIO1-VIO3 are used as the Y components of the shear force vector. At the same time, the magnitude of the resultant vector of the X component and the Y component in a rectangular coordinate system is used as the magnitude of the shear force on the flexible micro-dome shell (1), and the direction of the resultant vector is used as the direction of the shear force on the flexible micro-dome shell (1).

[0059] That is to say, the four-component force sensor device has independent pressure sensing capabilities in the four fan-shaped areas. When the flexible micro-dome shell is subjected to normal pressure, the signals of the four-component force sensor assembly will change in the same direction. When the flexible micro-dome shell is subjected to shear force, the signal change directions of the four-component force sensor assembly will be inconsistent. In this way, the sum of the four channel signal changes (ΔVIO0~3) is used as the device's response to the normal force, and the difference between the four channel signal changes (ΔVIO0-ΔVIO2, ΔVIO1-ΔVIO3) is used as the device's response to the shear force, thereby achieving simultaneous and accurate measurement of the normal force and shear force.

[0060] Further, refer to Figure 2 , the four fan-shaped electrodes of the sensor are connected in series as sensing units 9 and fixed resistors 8, and then the STM32 microcontroller 10 is used as an acquisition module to collect the voltage signal divided on the four fixed resistors, and then the voltage signal is transmitted to the PC terminal or VR terminal. Figure 1 As shown, the four sector-shaped sensing units of the upper electrode 4 are distributed in a cross shape, so the signals of the four sensing units are sequentially taken as VIO0, VIO1, VIO2, and VIO3 in a clockwise direction. As mentioned above, when the device is subjected to a normal force, VIO0~3 change in the same direction, and increase or decrease at the same time when the normal force changes. Therefore, the sum of VIO0~3 can represent the normal force exerted on the device; when the device is subjected to a shear force, the change direction of each unit signal is different, VIO0 and VIO2 change in opposite directions, and VIO1 and VIO3 change in opposite directions. Therefore, VIO0-VIO2 is taken as the X component of the shear force vector, and VIO1-VIO3 is taken as the Y component of the shear force vector. Then, the shear force exerted on the device is the resultant vector of the above X component and Y component in the rectangular coordinate system. The magnitude of the vector represents the magnitude of the shear force, and the direction is the direction of the shear force exerted on the device. The synthesis and decomposition of the vector is the coordinate conversion process from the plane rectangular coordinate system (x, y) to the plane polar coordinate system (ρ, θ).

[0061] It should be noted that the calculation process of the normal force and shear force size and direction can be realized through the C language program of the PC or VR terminal, and then the calculated finger operation data is used to control the machine side. At present, the functions of moving the cursor, clicking, and simulating key input on the PC side can be realized, and it has good compatibility with VR applications that can run on the PC side. Since the mechanical information that the device can obtain is not only a single normal force, but also multi-dimensional mechanical information of normal force, shear force direction, and shear force size, it can also realize more and more complex functions. At the same time, with multiple sensing units, it can basically cover most of the functions that traditional operating handles can complete.

[0062] In a preferred embodiment, the flexible micro-dome shell 1 is a hemisphere with a radius of 3 mm, and there is a space in the middle reserved for the rigid lining structure; at the same time, the shell of the force transmission structure adopts PDMS, and the ratio of the matrix to the cross-linking agent is selected to be 10:1; the rigid lining of the force transmission structure selects epoxy resin, and the ratio of components A and B is 1:1;

[0063] In a preferred embodiment, the rigid lining structure 2 is a cylinder with four triangular support structures. Preferably, the radius of the cylinder is 0.6 mm, the height is 2.6 mm, and the bottom side of the triangular support is 2 mm long, 2 mm high, and 0.8 mm wide.

[0064] In a preferred embodiment, the thickness of the upper and lower packaging layers is 100 micrometers; the material of the upper packaging layer (3) and the lower packaging layer (7) is polyimide PI.

[0065] In a preferred embodiment, the thickness of the upper and lower electrodes is about 50-100 microns; the material of the upper electrode layer (4) and the lower electrode layer (6) is conductive silver paste.

[0066] In a preferred embodiment, the upper electrode is in the form of four separate sectors, which are separated from each other by a cross with a width of 1 mm in the middle of a circle with a radius of 3 mm. Figure 1 As shown, each of the four areas is provided with a lead wire to lead them out, and the width of the lead wire is 0.5 mm;

[0067] In a preferred embodiment, the lower electrode is a whole circular piece with a radius of 3.5 mm, and is also provided with a 0.5 mm lead wire to lead it out;

[0068] In a preferred embodiment, the thickness of the varistor sheet is 100 microns, and the surface is not completely flat, but has a certain sandpaper-like microstructure; at the same time, the varistor sheet with relatively stable piezoresistive characteristics is selected as the varistor material, and the microstructure is modified by hot pressing to improve its sensitivity;

[0069] In a preferred embodiment, the fixed resistor is a P-103 potentiometer with an adjustable resistance of 10K; the signal collection and transmission uses an STM32 single-chip microcomputer.

[0070] Figure 3 The current change of the varistor after the introduction of the microstructure was demonstrated after 14,000 cycles of compression and release under a normal pressure of 41 kPa, indicating that the stability of the varistor after the introduction of the microstructure is still good.

[0071] The following describes the preparation process of the flexible omnidirectional force recognition sensor of the present invention.

[0072] The preparation of the sensor in the embodiment is divided into three parts. The first is the preparation process of the force transmission structure with a rigid lining:

[0073] 1) Two PLA plastic molds were printed using a melt extrusion 3D printer, one of which had a hemispherical groove with a radius of 3 mm, and the other had a cylindrical protrusion with four triangular support structures. The parameters of the protrusion were consistent with the shape and parameters of the rigid lining structure 2 in the above preferred embodiment, and no further description was given here;

[0074] 2) Weigh and mix the PDMS matrix and the cross-linking agent in a ratio of 10:1 on an electronic scale, stir with a glass rod until fully mixed, pour the PDMS into the mold, use a vacuum defoaming box to perform vacuum defoaming twice to remove excess air in the PDMS, and then heat the mold on a hot plate at 85°C for 2 hours;

[0075] 3) Peel off the raised side of the mold in the cured PDMS. At this time, there will be a pit reserved for the rigid lining structure on the flat side of the PDMS. Then weigh and mix the epoxy resin A and B components in a 1:1 ratio on an electronic scale, stir with a glass rod until fully mixed, pour the epoxy resin into the pit of the PDMS, and then use a vacuum defoaming box to perform vacuum defoaming twice to remove excess air in the epoxy resin. Keep the PDMS at room temperature for 24 hours;

[0076] 4) Peel off the cured epoxy resin and PDMS on the other side of the mold, and carefully remove the excess part with a blade, leaving the hemispherical dome and a clean flat side, to obtain the force conduction structure with a rigid liner in the embodiment for use;

[0077] Then comes the preparation process of the four-component force sensor device:

[0078] 1) After wiping both sides of the purchased varistor with anhydrous ethanol, use two pieces of 240-grit sandpaper as a template, clamp them on both sides of the varistor, and use a hot press to heat press at 50°C for 90 seconds;

[0079] 2) After the hot pressing is completed, the varistor sheet is cut into discs with a radius of 4 mm using a laser marking machine at low power output;

[0080] 3) Using a high-viscosity paste printer to print the upper and lower electrodes and their leads on the adhesive side of a single-sided PI tape with a thickness of 100 microns, using a silver paste material, the upper electrode is four separate sectors, the lower electrode is a whole circular piece, and the specific dimensions of the upper and lower electrodes and the leads are consistent with the parameters of the upper electrode layer 4 and the lower electrode layer 6 in the above preferred embodiment, and are not repeated here;

[0081] 4) After printing, place the PI tape on a hot plate at 105°C and heat for 5 minutes;

[0082] 5) After the silver paste is cured, place the PI tape with the upper electrode layer with the non-adhesive side facing upward into a plasma treatment machine and perform plasma treatment for 5 minutes to make the surface hydrophilic;

[0083] 6) Stack and assemble the two prepared PI tapes with upper and lower electrodes and the varistor disc. Note that the sides of the PI tape with the upper and lower electrodes are facing each other, and the varistor sheet is sandwiched in the middle. Since the side with the electrode is printed on the adhesive side, no additional fixing means is required;

[0084] Then comes the assembly of the four-component force sensor device and the force transmission structure with a rigid lining:

[0085] 1) Weigh and mix the PDMS substrate and the cross-linking agent in a ratio of 10:1 on an electronic scale, stir with a glass rod until fully mixed, and perform vacuum defoaming twice in a vacuum defoaming box to remove excess air in the PDMS for later use;

[0086] 2) Apply an appropriate amount of mixed, stirred and defoamed PDMS on the upper side of the packaging layer of the four-component force sensor device, that is, on the side of the PI tape with the upper electrode that has been treated with plasma, and then align the prepared force conduction structure with a rigid liner and adhere it to the upper side of the packaging layer of the four-component force sensor device. Here, the four triangular support structures of the rigid liner need to be aligned one by one with the four separated fan-shaped areas of the upper electrode layer to achieve the best shear force sensing effect;

[0087] 3) After alignment and adhesion, the device was placed on a 45° C. hot plate and allowed to stand for 12 hours, thereby completing the preparation of the flexible omnidirectional force recognition sensor in the embodiment.

[0088] Finally, the connection between the sensor and the microcontroller and the data processing on the VR device side:

[0089] 1) Lead out the lower electrode 6 of the prepared flexible omnidirectional force recognition sensor and connect it to the common source terminal of the single-chip microcomputer, such as Figure 2 As shown in the lower left part;

[0090] 2) The four electrodes of the upper electrode 4 of the flexible omnidirectional force recognition sensor are led out separately and connected in series with the potentiometers respectively. The other end of the potentiometer is connected to the common ground end of the single-chip microcomputer, such as Figure 2 As shown in the upper left part;

[0091] 3) Connect the four IO ports of STM32 to the non-ground terminal of the potentiometer, such as Figure 2 Shown in the middle left and right parts;

[0092] 4) Through single-chip computer programming, the four port voltage signals collected by STM32 are packaged and sent to the VR terminal through serial communication, and the serial port information is read and processed by C language to realize the operations of cursor movement, clicking, and simulated key input in VR virtual reality;

[0093] It should be noted that the choice of single-chip microcomputer can be not only STM32, but also various other chips and circuits with multi-channel voltage acquisition capabilities, so there are many alternatives for data transmission between the sensor and the machine terminal. At the same time, the present invention shows the ability of the sensor to control the VR device. In fact, as long as it supports various applications, programs, and interactive means running on the PC terminal, it can be realized through the sensor system. Therefore, there are many alternatives for the way the sensor controls the machine terminal.

[0094] To sum up, an embodiment of the present invention proposes a flexible omnidirectional force recognition sensor for transmitting finger operations in a VR device. The flexible omnidirectional force recognition sensor can fit well on the user's fingers and accurately sense the finger sliding direction and force information, thereby realizing a series of operations of the user in the VR device. Compared with the operation method of traditional operating handles or smart gloves, since the sensor is small and light, the human hand will not be overly burdened in this operation mode, and will not feel fatigued even if used for a long time, and it has a more immersive interactive experience, which provides a new idea for the next generation of VR device operation interaction mode.

[0095] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may certainly make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A sensor for transmitting finger operation in a VR device, characterized in that: It includes a force transmission structure, a four-component force sensor component, a voltage-dividing resistor component, a collection module and a processing module; The four-component force sensor assembly comprises, from top to bottom, an upper packaging layer (3), an upper electrode layer (4), a piezoresistor layer (5), a lower electrode layer (6) and a lower packaging layer (7); wherein the upper electrode layer (4) is composed of four separate sector-shaped electrodes that can be combined into a full circle, and the lower electrode layer (6) is a complete circular electrode, thereby dividing the piezoresistor layer (5) located between the upper electrode layer (4) and the lower electrode layer (6) into four piezoresistors; The voltage-dividing resistor assembly is composed of four fixed resistors with the same resistance value, and one end of each fixed resistor is connected in series with a sector electrode, and the other end is connected to a common ground terminal; The force transmission structure is composed of a flexible micro-dome outer shell (1) and a rigid lining structure (2); wherein the rigid lining structure (2) has four branches distributed in a cross shape, and each branch is bonded to the upper packaging layer (3), and at the same time, the projection of each branch on the upper packaging layer (3) corresponds one-to-one to the projection of each sector electrode on the upper packaging layer (3); the rigid lining structure (2) is used to transmit the pressure exerted on the flexible micro-dome outer shell (1) to each piezoresistor; When measuring the pressure on the flexible micro-dome housing (1), a constant voltage is applied to the lower electrode layer (6), and the divided voltage of four fixed resistors is measured through the acquisition module, wherein the pressure components borne by each piezoresistor are different, and the divided voltage of the corresponding fixed resistor is different; The processing module determines the type and magnitude of the pressure according to the change directions and magnitudes of the four partial pressures, wherein the types of pressure are shear force and normal force.

2. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The method for determining the pressure category to which the flexible micro-dome housing (1) is subjected is as follows: It is determined whether the directions of change of the four partial pressures are the same. If so, the pressure on the flexible micro-dome shell (1) is a normal force; if not, the pressure on the flexible micro-dome shell (1) is a shear force, wherein the direction of change includes increase and decrease.

3. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The method for determining the magnitude of the pressure on the flexible micro-dome housing (1) is as follows: The four divided voltages corresponding to the four sector electrodes are recorded as VIO0, VIO1, VIO2, and VIO3 in a clockwise direction; Determine whether the directions of change of the four partial pressures are the same; if so, the pressure on the flexible micro-dome housing (1) is a normal force, and the sum of VIO0, VIO1, VIO2, and VIO3 is used as the magnitude of the normal force on the flexible micro-dome housing (1); wherein the direction of change includes increase and decrease; If not, the pressure on the flexible micro-dome shell (1) is a shear force, VIO0 and VIO2 are used as the X component of the shear force vector, VIO1-VIO3 are used as the Y component of the shear force vector, and at the same time, the magnitude of the resultant vector of the X component and the Y component in the rectangular coordinate system is used as the magnitude of the shear force on the flexible micro-dome shell (1), and the direction of the resultant vector is used as the direction of the shear force on the flexible micro-dome shell (1).

4. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The material of the upper packaging layer (3) and the lower packaging layer (7) is polyimide PI.

5. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The material of the upper electrode layer (4) and the lower electrode layer (6) is conductive silver paste.

6. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The radius of the full circle formed by the upper electrode layer (4) is smaller than the radius of the circular electrode of the lower electrode layer (6).

7. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The preparation method of the force transmission structure is as follows: 1) Use a melt extrusion 3D printer to print two PLA plastic molds, one of which has a hemispherical groove with a radius of 3 mm, and the other has a cylindrical protrusion with four triangular support structures; 2) Weigh and mix the PDMS matrix and the cross-linking agent in a ratio of 10:1 on an electronic scale, stir with a glass rod until fully mixed, pour the PDMS mixture into a PLA plastic mold, perform vacuum defoaming twice in a vacuum defoaming box, and then heat the PLA plastic mold on a hot plate at 85°C for 2 hours; 3) Peel off the raised PLA plastic mold on the solidified PDMS. At this time, there will be a pit reserved for the rigid lining structure on the flat side of the PDMS. Then weigh and mix the epoxy resin A and B components in a 1:1 ratio on an electronic scale, stir with a glass rod until fully mixed, pour the epoxy resin mixture into the pit of the PDMS, and then use a vacuum defoaming box to perform vacuum defoaming twice, and keep the PDMS at room temperature for 24 hours; 4) The cured epoxy resin and PDMS are peeled off on the other side of the mold, and the excess part is removed with a blade, leaving the hemispherical dome and the flat side to obtain a force conduction structure with a rigid lining.

8. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The preparation method of the four-component force sensor assembly is as follows: 1) After wiping both sides of the varistor clean with anhydrous ethanol, use two pieces of 240-grit sandpaper as a template, clamp them on both sides of the varistor, and use a hot press to heat press at 50°C for 90 seconds; 2) After the hot pressing is completed, the varistor sheet is cut into discs with a radius of 4 mm using a laser marking machine; 3) Using a paste printer, a silver paste material is used to print the upper electrode, the lower electrode and their leads on the adhesive side of a single-sided PI tape with a thickness of 100 microns, wherein the upper electrode is four separate sectors and the lower electrode is a whole circular piece; 4) After printing, place the PI tape on a hot plate at 105°C and heat for 5 minutes; 5) After the silver paste material is cured, place the PI tape with the upper electrode layer with the non-adhesive side facing upward into a plasma treatment machine and perform plasma treatment for 5 minutes to make the surface hydrophilic; 6) The two prepared PI tapes with the upper electrode and the lower electrode are stacked and assembled with the varistor sheet to obtain a four-component force sensor assembly.

9. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The assembly method of the four-component force sensor assembly and the force transmission structure is as follows: 1) Weigh and mix the PDMS substrate and the cross-linking agent in a ratio of 10:1 on an electronic scale, stir the mixture with a glass rod until it is fully mixed, and then use a vacuum defoaming box to perform vacuum defoaming twice to remove excess air in the PDMS for later use; 2) Applying the mixed, stirred and defoamed PDMS on the upper side of the upper packaging layer of the four-component force sensor assembly, and then aligning the prepared force conduction structure with a rigid liner and adhering it to the upper side of the upper packaging layer of the four-component force sensor assembly, wherein the four branches of the rigid liner structure are aligned one by one with the four separated sector-shaped electrodes of the upper electrode layer; 3) After alignment and adhesion, the adhered device is placed on a 45° C. hot stage for 12 hours to complete the assembly of the four-component force sensor assembly and the force conduction structure.

10. A sensor for transmitting finger operation in a VR device as claimed in claim 1, characterized in that: The acquisition module packages the four collected partial pressures and sends them to the VR terminal where the processing module is located through serial communication. The processing module determines the type and size of the pressure, and then controls the cursor in the VR virtual reality to move in the direction of the shear force, ultimately realizing the cursor click and simulated key input in the VR virtual reality.

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