Optical waveguide sensor, wet and soft substance adhering and grabbing device based on flexible optical waveguide and control method of wet and soft substance adhering and grabbing device

Abstract

The invention provides an optical waveguide sensor, a wet and soft substance adhering and grabbing device based on a flexible optical waveguide and a control method of the wet and soft substance adhering and grabbing device based on the flexible optical waveguide. A camera base, a limiting copper column, a USB infrared camera, an electromagnet, a rotary guide rail, a vertical guide rail, a magnetic drive layer, an acrylic hard waveguide, an LED programmable controller, an infrared light source and a support are arranged in the sensor shell, and the wet and soft substance adhesion grabbing device comprises a UR5 mechanical arm, an electric clamping jaw and an optical waveguide sensor. Through the leakage light characteristic of the optical waveguide, the contact area and adhesion strength change of an adhesion interface can be monitored in real time, high-precision control and real-time feedback of the wet and soft matter grabbing process are achieved, magnetic field parameters can be dynamically adjusted according to the actual adhesion state, the debonding effect is optimized, intelligent control and precise and controllable debonding are achieved, and the grabbing efficiency of the wet and soft matter is improved. The problem of excessive debonding or insufficient debonding is avoided, and the target object is not prone to being damaged.

Description

Technical Field

[0001] This invention relates to the fields of robotic grasping and medical technology, and in particular to an optical waveguide sensor and a wet soft material adhesion and grasping device based on a flexible optical waveguide, and its control method. Background Technology

[0002] Currently, traditional grasping technologies have made significant progress in industrial robots, service robots, and the medical field, but they still face many challenges in terms of adaptability, accuracy, and stability. Most mainstream tactile sensors are based on resistive or piezoelectric principles. These sensors not only require direct contact with the target object but also rely on changes in the electrical or mechanical properties of the material to acquire tactile information. However, when dealing with flexible, wet surfaces, these sensors exhibit significant limitations—especially in applications such as grasping operations on wet surfaces or intraoperative procedures, where their performance stability struggles to meet the requirements of high-precision operations. Wet, soft materials, due to their unique physical characteristics (such as irregular shape, soft texture, and wet surface), pose a severe challenge to traditional rigid grasping technologies. To overcome this technological bottleneck, developing novel grasping technologies based on flexible materials and high-precision sensing systems has become a key research direction. These technologies can not only better adapt to the characteristics of wet, soft materials but also achieve stable and precise operations in complex environments, bringing revolutionary breakthroughs to the industrial, service, and medical fields.

[0003] Soft, wet materials are extremely sensitive to external pressure, and traditional direct-contact sensors can easily cause deformation or even damage to the object. In contrast, optical waveguide leakage technology, with its unique advantage of non-contact measurement, can accurately monitor applied pressure without disturbing the target object. This characteristic makes it significantly superior in grasping soft, fragile objects. More importantly, traditional pressure sensors have significant shortcomings in resolution and sensitivity, making it difficult to capture minute pressure changes during the grasping of soft, wet materials.

[0004] Optical waveguide tactile sensors are a new type of sensor that senses external pressure information by detecting changes in light signals, based on the optical properties of optical waveguide materials. According to the differences in their working principle and application scenarios, optical waveguide sensors are mainly divided into the following three types: (1) Optical waveguide leakage sensor: Its core principle is based on the phenomenon of total internal reflection. Under no external force, light propagates along the waveguide path in the core layer of the optical waveguide through total internal reflection; when external pressure is applied to the surface of the optical waveguide, the waveguide structure will deform (bend or stretch), causing some light to leak. By accurately monitoring the change in the intensity of the leaked light, the magnitude and distribution information of the externally applied force can be deduced. (2) Optical waveguide marker displacement sensor: This type of sensor embeds a specific marker inside the optical waveguide. When an external force is applied to the sensor, the elastic body will deform, thereby causing the marker to undergo spatial displacement. By capturing the displacement change of the marker with a high-precision detector, the magnitude and direction of the applied force can be accurately calculated. (3) Reflective Film Type Optical Waveguide Sensor: This sensor employs a specially designed reflective film structure. Incident light is reflected by the reflective film inside the elastic optical waveguide before entering the detector. When an external force is applied, the local slope of the reflective film changes, thus affecting the light intensity signal received by the detector. By analyzing the characteristics of the light intensity change, the magnitude and distribution of the applied force can be accurately calculated. However, although traditional optical waveguide sensors have the advantage of non-contact measurement, they suffer from poor signal stability due to the single waveguide structure in flexible and wet surface environments, making it difficult to balance mechanical support and optical sensing.

[0005] Traditional rigid gripping systems often apply excessive force when handling wet, soft objects, especially in scenarios requiring gentle handling, easily leading to object crushing or damage. Traditional magnetic debonding methods typically rely on uniform magnetic fields or single magnetic materials, making it difficult to achieve precise local control and adaptive operation. Consequently, traditional adhesion technologies exhibit unstable performance in wet environments, hindering efficient and reliable adhesion. Furthermore, traditional sensors lack real-time feedback mechanisms, preventing dynamic adjustment of adhesion preload, which can easily lead to object damage or gripping failure. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an optical waveguide sensor.

[0007] The technical problem to be solved by the present invention is to provide a wet soft material adhesion and gripping device based on a flexible optical waveguide, including the above-mentioned optical waveguide sensor.

[0008] Another technical problem to be solved by the present invention is to provide a control method for the above-mentioned wet soft material adhesion and gripping device based on flexible optical waveguide.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0010] An optical waveguide sensor includes a sensor housing. Inside the sensor housing are a camera base 4, a limiting copper pillar 5, a USB infrared camera 6, an electromagnet 7 (preferably a ring structure), a rotating guide rail 8, a vertical guide rail 9, a magnetic drive layer 10, an acrylic (PMMA) rigid waveguide 12, an LED programmable controller 13, an infrared light source 14, and a bracket 15. The LED programmable controller 13 is located outside the vertical guide rail 9 and is connected to the infrared light source 14 via signal lines to control the switching and parameters of the infrared light source 14. The infrared light source 14 is mounted on the bracket 15 and is used to adjust the angle at which light enters the acrylic rigid waveguide 12 to ensure total internal reflection within the waveguide. The acrylic rigid waveguide 12... The surface is perpendicular to the optical axis of the USB infrared camera 6 and its leakage light area is within the focal plane or depth of field of the camera, enabling the camera to clearly image the leakage light distribution. The camera base 4 is fixedly connected to the sensor housing, and the USB infrared camera 6 is fixedly connected to the camera base 4 through the limiting copper pillar 5. The acrylic rigid waveguide 12 is provided with microstructures 16. The electromagnet 7 is connected to the vertical guide rail 9 through the rotating guide rail 8. The rotating guide rail 8 is responsible for adjusting its horizontal position, and the vertical guide rail 9 is used for adjusting its vertical height, thereby realizing spatial control of the direction and intensity of the magnetic field. The magnetic drive layer 10 is located below the acrylic rigid waveguide 12, closely attached to the acrylic rigid waveguide 12, and located within the range of the magnetic field generated by the electromagnet 7.

[0011] Preferably, in the above-mentioned optical waveguide sensor, the number of infrared light sources 14 is 12, and each LED infrared light source 14 is symmetrically distributed around the acrylic rigid waveguide 12, so as to uniformly couple light into the acrylic rigid waveguide 12 from the side, to provide sufficient optical signal for the optical waveguide to achieve accurate monitoring of the adhesion of wet soft material. When the optical waveguide comes into contact with the target object to be adhered, the pressure change at the contact interface will cause the refractive index distribution and optical transmission characteristics of the optical waveguide to change, thereby causing optical signal leakage.

[0012] Preferably, the above-mentioned optical waveguide sensor further includes an adhesion layer 11. The adhesion layer 11 (as a functional layer) and the acrylic rigid waveguide 12 (as a substrate layer) together form a composite optical waveguide structure, which integrates light transmission, mechanical support and sensing functions. The adhesion layer 11 is disposed on the acrylic rigid waveguide 12.

[0013] Preferably, in the aforementioned optical waveguide sensor, the acrylic rigid waveguide 12 is made of a rigid transparent material with a first refractive index, such as polymethyl methacrylate (PMMA). Its main technical advantage is providing stable mechanical support and serving as the initial injection and transmission path for optical signals. Optical signals coupled from an external light source are efficiently guided to the adhesion layer 11 through the acrylic rigid waveguide 12. The adhesion layer 11 is made of a flexible transparent material with a second refractive index, such as polydimethylsiloxane (PDMS), and the second refractive index is typically slightly lower than the first refractive index. Because the difference in refractive indices between the two materials is small, light will not undergo significant refraction within it, thus still satisfying the condition for total internal reflection. The adhesion layer 11 is tightly bonded to the acrylic rigid waveguide 12 through a bonding method, forming a continuous optical interface.

[0014] Preferably, in the above-mentioned optical waveguide sensor, the outer surface of the adhesion layer 11 is a sensing interface, and the sensing interface is provided with microstructures 16 for optical interaction with external targets or the environment.

[0015] Preferably, in the above-mentioned optical waveguide sensor, the microstructures 16 on the adhesion layer 11 are arranged in a gradient manner (dense in the middle and sparse at the edges).

[0016] Preferably, in the above-mentioned optical waveguide sensor, the magnetic drive layer 10 has a hollow design in the middle, forming a magnetic drive ring structure.

[0017] Preferably, in the aforementioned optical waveguide sensor system, the magnetic field parameters of the electromagnet 7 are dynamically adjusted according to the actual adhesion conditions. Specifically, the desired debonding speed v is determined based on the characteristics of the wet, soft material to be processed and the application scenario. d At the same time, set the initial value of k1 (k1 is the debonding speed adjustment coefficient);

[0018] Calculate the initial magnetic field strength B0 and direction B0 using the formula B0 = k1 × F. d θ0 is initially set according to the device structure and the requirements of the debonding direction, and the initial magnetic field strength B0 and magnetic field direction B0 are obtained and applied to the electromagnet 7.

[0019] During the debonding process, the current debonding speed v is monitored in real time using an optical waveguide detection mechanism. current Adjustments are made based on the difference between the monitored current speed and the expected value. If v current <v d B new =B current +k1×(v d -v current If v current >v d B new =Bcurrent -k1×(v d -v current ).

[0020] Preferably, in the above-mentioned optical waveguide sensor, light enters the optical waveguide from a medium with a refractive index of n1 and propagates within it. The refractive index of the optical waveguide is n0, the refractive index of the inner medium of the optical waveguide is also n1, and the refractive index of the outer medium of the optical waveguide is n2. The incident medium and the inner medium of the waveguide are both air, and the outer medium is water or the object to be adhered to, where n2 > n1. The propagation of light in the optical waveguide follows the law of refraction, and the incident angle θ0 of the incident light in the optical waveguide should satisfy the following condition:

[0021]

[0022] The effective incident angle range for total internal reflection within the waveguide can be determined by this condition. Then, by adjusting the angle of the light source support 15, the angle at which the light is incident on the waveguide can be changed to keep it within a reasonable angle.

[0023] Preferably, in the aforementioned optical waveguide sensor, the hexagonal structure dimensions (such as side length and height) of the microstructure 16 are optimized according to the characteristics of the target surface. The optimization of the hexagonal structure dimensions mainly involves the design of the side length L and height H. The side length L determines the contact area and distribution density of the hexagonal structure, and the optimization formula for the side length L is:

[0024]

[0025] In the formula, F ad γ is the required adhesion force, γ is the interfacial energy, and N is the distribution density of the hexagonal structure (the number of hexagonal structures per unit area). The height H determines the deformation capacity and adaptability of the hexagonal structure, and the optimization formula for height H is:

[0026]

[0027] In the formula, E is the elastic modulus of the material, and ΔA is the change in contact area.

[0028] Preferably, in the above-mentioned optical waveguide sensor, the material of the adhesion layer 11 is polydimethylsiloxane (PDMS), which has high transparency, flexibility and biocompatibility.

[0029] Preferably, in the above-mentioned optical waveguide sensor, the method for preparing the adhesive layer 11 is as follows: PDMS (prepolymer / crosslinking agent ratio of 10:1, prepolymer being polydimethylsiloxane, and crosslinking agent being hydrogen-containing siloxane) is poured onto a soft rubber mold with microstructure (80mm-120mm), vacuumed to remove air bubbles, and cured in a drying oven at 60°C for 12 hours, and then demolded to obtain the adhesive layer containing microstructure 16.

[0030] PDMS not only effectively transmits optical signals but also maintains stable performance in humid environments. Furthermore, the flexibility of PDMS allows it to adapt to the deformation of complex surfaces, ensuring that the optical waveguide does not fail due to excessive deformation during the grasping process.

[0031] Preferably, in the aforementioned optical waveguide sensor, the magnetic drive layer 10 adopts a gradient concentration design, which not only allows the light leaked by the optical waveguide to pass through, but also enables precise gradient force control.

[0032] Preferably, in the above-mentioned optical waveguide sensor, the magnetic drive layer uses iron tetroxide (Fe3O4) nanoparticles as the magnetic functional phase and polydimethylsiloxane (PDMS) as the flexible matrix, and achieves controllable magnetic response through gradient dispersion and magnetic field orientation processes.

[0033] Preferably, in the above-mentioned optical waveguide sensor, the magnetic driving layer is prepared as follows: First, Fe3O4 nanoparticles (particle size 50-100nm) are surface modified (using a conventional polymer coating method, forming a polymer shell (such as polyethylene glycol) on the particle surface to enhance its biocompatibility, dispersion stability, and subsequent functionalization capability); then, a magnetic PDMS composite material is prepared according to a gradient concentration design—the edge region uses 5-10% Fe3O4 by mass to ensure flexibility and light transmittance, while the central region increases to 20-30% to enhance the magnetic driving force; the PDMS prepolymer is then combined with... The crosslinking agents (prepolymer is polydimethylsiloxane, crosslinking agent is hydrogen-containing siloxane) are mixed at a ratio of 10:1 and injected into Fe3O4 slurry in sections. The slurry is then circulated using a three-roll mill to ensure uniform dispersion. After vacuum degassing, the slurry is injected into a ring mold. A stepped curing process is used during molding: first, the gradient structure is initially fixed by pre-curing at 60℃ for 10 minutes; then, a 0.5T axial magnetic field is applied to orient the Fe3O4 particles along the magnetic lines of force to enhance magnetic anisotropy; finally, the slurry is completely cured at 80℃ for 2 hours. After demolding, the magnetic drive layer is magnetized by a pulsed magnetic field (3T, 10ms) to increase the remanence to 0.4T.

[0034] To optimize performance, the aforementioned optical waveguide sensor achieves rapid magnetic response (deformation delay <10ms) in the central region through high-concentration Fe3O4 and magnetic field orientation. The low-concentration design in the edge region triggers warping under a weak magnetic field of 50mT, achieving graded debonding. Simultaneously, the PDMS matrix imparts a break elongation of >150% to the material. Utilizing the high flexibility and low elastic modulus of PDMS, Fe3O4 particles are uniformly dispersed in PDMS. This allows the material to retain the excellent mechanical properties of PDMS while enabling magnetic field response (such as deformation and warping) through Fe3O4, thus adapting to complex surface deformations. In terms of light transmittance, the 5% Fe3O4 region has a transmittance of >85% at a wavelength of 600nm, ensuring optical compatibility with the upper-layer optical waveguide.

[0035] A wet soft material adhesion and gripping device based on a flexible optical waveguide includes a UR5 robotic arm 1, an electric gripper 2, and the aforementioned optical waveguide sensor 3. The electric gripper 2 is fixed to the end of the UR5 robotic arm 1, and the optical waveguide sensor 3 is mounted on the electric gripper 2 through its sensor housing.

[0036] The control method for the aforementioned flexible optical waveguide-based wet soft material adhesion and gripping device is as follows:

[0037] (1) Start preparation: Confirm that all components of the device are installed correctly and in the initial state, place the target object to be adhered on the glass slide 18, and fix the glass slide 18 to the top surface of the three-dimensional displacement stage 19;

[0038] (2) The robotic arm sets a preload force for adhesion contact: By controlling the UR5 robotic arm, the adhesion layer 11 of the optical waveguide sensor moves towards and contacts the target object to be adhered. An initial preload force is set according to the properties (shape, material, etc.) of the target object to be adhered and the adhesion process begins.

[0039] (3) Optical waveguide detection of adhesion interface information: The infrared light source 14 emits light under the control of the LED programmable controller 13, and the light signal is transmitted to the area where the optical waveguide sensor 3 is located, providing illumination for the optical waveguide sensor 3; After the adhesion layer 11 comes into contact with the target object being adhered, the pressure change at the contact interface causes the optical waveguide refractive index distribution and light transmission characteristics to change, resulting in light signal leakage, and the USB infrared camera 6 captures the changes in the leakage light.

[0040] (4) Determine whether the adhesion and gripping conditions are met: Based on the changes in the light signal captured by the USB infrared camera 6, accurately calculate the contact area and adhesion strength, and determine whether the adhesion and gripping conditions are met. If not, return to step (2) and increase the preload force, and continue monitoring and adjustment; if met, proceed to the next step.

[0041] (5) Grasping, Transfer and Debonding: After the adhesion and gripping conditions are met, the UR5 robotic arm 1 grasps the target object to be adhered and transfers it to the designated target position. After reaching the designated position, a debonding operation is required. The spatial orientation of the electromagnet 7 is adjusted by the rotating guide rail 8 / vertical guide rail 9. The magnetic field generated by the electromagnet acts on the magnetic drive layer 10, causing it to deform and drive the adhesion layer 11 to lift and debond. During the debonding process, the optical waveguide sensor 3 monitors the adhesion interface status in real time. The system dynamically adjusts the magnetic field parameters of the electromagnet 7 according to the actual adhesion situation to optimize the debonding effect and ensure smooth debonding.

[0042] (6) End of operation: Debonding is complete, the device returns to the initial state and waits for the next operation command.

[0043] Preferably, in the control method of the above-mentioned wet soft material adhesion and gripping device based on flexible optical waveguide, the event-driven reversible adhesion strategy is adopted in step (4). When the adhesion layer 11 contacts and adheres to the target object 17 and is lifted, if the contact area suddenly decreases in a short time, it indicates that the object surface or adhesion strength has decreased sharply. If the rate of change of the contact area exceeds the preset threshold, that is, the de-adhesion rate is greater than the set threshold, the system should determine that the adhesion does not meet the stable gripping conditions and increase the preload force to perform adhesion and gripping again.

[0044] The event-driven reversible adhesion strategy uses changes in light signal intensity. After the adhesion layer 11 comes into contact with the target object 17, light leaks due to pressure on the surface of the adhesion layer 11. When the adhesion strength weakens, the light signal intensity suddenly decreases. When the rate of change of light signal intensity exceeds a preset threshold, the preload force is increased to perform adhesion and gripping again.

[0045] Preferably, the control method of the above-mentioned wet soft material adhesion and gripping device based on flexible optical waveguide adopts different countermeasures according to different adhesion event types: if the contact area suddenly decreases, it means that the risk of the object sliding or adhesion failure has increased. At this time, the control system will increase the preload of the robotic arm and simultaneously adjust the magnetic field parameters of the electromagnet 7 to enhance the adhesion force between the adhesion layer 11 and the target object 17 to stabilize the adhesion state; conversely, if the contact area increases rapidly and the adhesion strength approaches saturation, resulting in over-adhesion and object deformation, the control system will appropriately reduce the preload and fine-tune the magnetic field parameters as needed to keep the adhesion force within a suitable range, thereby achieving precise adaptive adhesion control.

[0046] Preferably, in the control method of the above-mentioned wet soft material adhesion and gripping device based on flexible optical waveguide, the leakage light image acquired by the entire optical waveguide sensor and the computer's image processing algorithm together constitute a dynamic feedback control system. The core of the dynamic feedback control system lies in adjusting the preload force by real-time monitoring of the adhesion interface state to form a closed-loop control. The acrylic rigid waveguide 12, infrared light source 14, and USB infrared camera 6 constitute the sensing layer for the optical waveguide sensor to capture changes in leakage light intensity; the decision layer uses a proportional-integral (PI) control algorithm to determine whether to trigger a control action, i.e., whether the de-adhesion rate is greater than a set threshold; the UR5 robotic arm 1, electric gripper 2, rotary guide rail 8, and vertical guide rail 9 constitute the execution layer for the robotic arm to adjust the preload contact; the proportional-integral (PI) control algorithm is as follows:

[0047]

[0048] In the formula, e(t) is the error signal, i.e., the deviation between the predetermined value and the actual value of the adhesion area change; KP is the proportional gain; and ki is the integral gain. The magnitude of the preload required for the next adhesion gripping is calculated using the deviation value of the area change rate in a closed loop.

[0049] Preferably, the control method of the above-mentioned wet soft material adhesion and gripping device based on flexible optical waveguide achieves an efficient bubble discharge mechanism by controlling the bending of the adhesion layer 11 through magnetic drive: when the optical waveguide adhesion layer comes into contact with the target object being adhered to, the magnetic drive layer 10 deforms under the action of the magnetic field, causing the adhesion layer 11 to produce gradient bending. This bending causes the adhesion layer 11 to gradually adhere to the surface of the object from the center to the edge, forming a squeezing effect from the inside out, thereby gradually discharging the bubbles between the contact interfaces; the initial adhesion in the central region ensures that the bubbles are not trapped in the center, while the gradual adhesion in the edge region guides the bubbles to move outward and eventually discharge them.

[0050] Preferably, the control method of the above-mentioned wet soft material adhesion and gripping device based on flexible optical waveguides involves placing the optical waveguide sensor 3 on the electric gripper 2, and achieving gripping of both sides of the wet soft material through the opening and closing of the gripper; in the initial state, the robotic arm adjusts the angle so that the optical waveguide adhesion layer on both sides adheres to the surface of the target object, and the microstructure 16 forms a stable adhesion using capillary force and negative pressure; the optical waveguide sensor monitors the change of adhesion force at the contact interface on both sides in real time and feeds the data back to the control system; the control system, including the UR5 robotic arm 1, electric gripper 2, rotary guide rail 8 and vertical guide rail 9, adjusts the gripping force of the robotic gripper in real time according to the feedback information from the optical waveguide monitoring interface to ensure stability during the gripping process and avoid excessive force that could damage the object; after gripping, the opening and closing degree of the robotic gripper is adjusted and combined with magnetic control to warp the optical waveguide adhesion layer, achieving gradual deadhesion from the outside to the inside, reducing damage to the object.

[0051] Beneficial effects:

[0052] The aforementioned optical waveguide sensor, through a PMMA / PDMS composite waveguide structure, monitors the adhesion interface and dynamically adjusts the preload during the gripping process of wet and soft materials. This ensures the stability, precise and accurate control, and non-destructive operation of the device during gripping. It not only dynamically adjusts the adhesion preload based on the interface image information detected by the optical waveguide but also enables efficient debonding after gripping. Furthermore, through the biomimetic structural design and the selection of elastic materials, the adhesion strength is significantly enhanced in humid environments while effectively avoiding pressure and damage to wet and soft objects. This refined control and intelligent feedback allows the application device to significantly improve the efficiency, stability, and adaptability of gripping wet and soft objects, especially in dynamic environments and with complex objects. It significantly improves the gripping accuracy of automated systems, achieving high adhesion strength while providing efficient debonding mechanisms and strategies.

[0053] The flexible optical waveguide-based wet soft material adhesion and gripping device combines optical waveguide sensing technology. Utilizing the light leakage characteristics of the waveguide, it can monitor changes in the contact area and adhesion strength of the adhesion interface in real time, achieving high-precision control and real-time feedback of the wet soft material gripping process. This real-time feedback mechanism allows the system to dynamically adjust magnetic field parameters according to the actual adhesion state, optimizing the de-adhesion effect and achieving intelligent control and precise controllable de-adhesion, avoiding excessive or insufficient de-adhesion and minimizing damage to the target object. Furthermore, the gradient-distributed microstructure design not only achieves high adhesion strength in the central region but also facilitates de-adhesion in the lower adhesion strength of the edge regions, reducing the device's operational difficulty and energy consumption. Specifically:

[0054] 1. The optical waveguide adhesion layer can monitor changes in the contact area during the grasping process in real time and derive the debonding rate of the interface based on image information captured by the camera. This allows for the calculation of the preload increment, ensuring precise control of the grasping force and preventing damage to the object due to excessive force or grasping failure due to insufficient force. The optical signal transmission between the optical waveguide adhesion layer and the wet, soft material does not require direct contact, avoiding the mechanical damage to wet, soft materials caused by traditional sensors. This technology also enables the spatial distribution measurement of the interface adhesion strength, providing more comprehensive adhesion information. Furthermore, the optical waveguide adhesion layer is extremely sensitive to minute changes in the interface refractive index and morphology, capable of detecting nanoscale or microscale changes in adhesion force. The extremely fast transmission and detection speed of the optical signal enables real-time monitoring and feedback of the adhesion strength.

[0055] 2. The biomimetic microstructure design solves the problem of gripping slippery and soft objects using traditional rigid gripping tools. This invention designs a biomimetic microstructure that achieves efficient adhesion to soft materials in wet environments with relatively low preload. This design significantly improves the stability and adaptability of adhesion on complex surfaces. The gradient design of the microstructure not only achieves high adhesion strength in the central region, but also allows the debonding process to start from the edge and gradually extend towards the center, significantly reducing the force required for debonding, thereby reducing operational difficulty and energy consumption.

[0056] 3. Regarding the control strategy, this invention achieves real-time monitoring and dynamic adjustment through optical waveguide technology. Combined with an event-driven strategy and a closed-loop control algorithm, it significantly improves the accuracy, stability, and intelligence level of wet and soft material adhesion and gripping. Specifically, this invention innovatively proposes an event-driven reversible adhesion strategy, which accurately judges the stability of the adhesion state by monitoring the rate of change of the adhesion area or the rate of change of the light signal intensity in real time. When abnormal fluctuations in the adhesion area or light signal intensity are detected, the system can quickly respond and trigger control actions to ensure that the adhesion process remains stable. In addition, this invention adopts a proportional-integral (PI) control algorithm to achieve precise adjustment of the preload force through closed-loop control. The system dynamically calculates the increment of the preload force based on the deviation between the actual value and the target value of the adhesion area, and performs adjustments through a robotic arm to ensure that the preload force is always within the optimal range. This closed-loop control mechanism can not only respond quickly to changes in the adhesion state, but also effectively avoid gripping failure or object damage caused by excessive or insufficient preload force, thus providing an efficient, accurate, and reliable solution for the adhesion and gripping of wet and soft materials.

[0057] 4. The magnetic control method features non-contact and rapid response, making it suitable for scenarios requiring frequent adhesion and debonding. The design of an electromagnet and a magnetic drive ring enables efficient control of the adhesive layer. The magnetic drive ring responds to changes in the magnetic field, causing the adhesive layer to peel off at the edges. This design not only improves debonding efficiency but also makes the debonding process more controllable and precise. By adjusting the strength and direction of the magnetic field, the debonding force and speed can be precisely controlled, thus adapting to different application requirements.

[0058] 5. In the debonding process, the electromagnet and the magnetic drive ring work together. The hollow design of the magnetic drive ring ensures light transmission through the optical waveguide, keeping the debonding process under constant camera monitoring. The system dynamically adjusts the magnetic field parameters of the electromagnet based on the interface state detected by the optical waveguide, precisely controlling the magnetic drive ring to drive the optical waveguide adhesion layer to detach. The hollow design of the magnetic drive ring facilitates light transmission through the optical waveguide, enabling the optical waveguide detection mechanism to monitor the adhesion interface state in real time. This combination of magnetic control technology and optical waveguide sensing technology not only improves the system's intelligence level but also enables real-time monitoring and adjustment of the adhesion process. Optical waveguide feedback allows for real-time acquisition of contact area and adhesion strength information at the adhesion interface, further optimizing the magnetically controlled debonding effect. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the overall structure of the adhesion device of the present invention.

[0060] Figure 2 This is a schematic diagram of the mechanical gripper structure at the end of the robotic arm of the present invention.

[0061] Figure 3This is a structural design diagram of the optical waveguide sensor in the end effector of the robotic arm of the present invention.

[0062] Figure 4 This is a schematic diagram of the flexible optical waveguide of the present invention leaking light under stress.

[0063] Figure 5 This is a schematic diagram of the camera of the present invention receiving leaked light and displaying a contact image.

[0064] Figure 6 This is a flowchart of the control logic for the precise adhesion of wet and soft materials by a robotic arm, as described in this invention.

[0065] In the diagram: 1-UR5 robotic arm, 2-electric gripper, 3-optical waveguide sensor, 4-camera base, 5-limiting copper column, 6-USB infrared camera, 7-electromagnet, 8-rotary guide rail, 9-vertical guide rail, 10-magnetic drive layer, 11-adhesion layer, 12-acrylic rigid waveguide, 13-LED programmable controller, 14-infrared light source, 15-support, 16-microstructure, 17-target object to be adhered, 18-glass slide, 19-three-axis displacement stage. Detailed Implementation

[0066] The following description, in conjunction with embodiments and accompanying drawings, illustrates the wet soft material adhesion and gripping device based on flexible optical waveguides according to the present invention.

[0067] Example 1

[0068] like Figure 1-5 As shown, the flexible optical waveguide-based wet soft material adhesion and gripping device utilizes flexible optical waveguide sensing technology to obtain the intensity change of leaked light. By monitoring information such as the contact area and adhesion strength of the adhesion interface in real time, it precisely controls the magnitude of the adhesion preload, achieving high-efficiency adhesion strength with low preload. Specifically, the device includes a UR5 robotic arm 1, an electric gripper 2 (Huiling Technology Z-EFG-50 electric gripper), and an optical waveguide sensor 3. The electric gripper 2 is fixed to the end of the UR5 robotic arm 1, and the optical waveguide sensor 3 is mounted on the electric gripper 2 through its sensor housing.

[0069] The aforementioned optical waveguide sensor 3 includes a sensor housing, within which are housed a camera base 4, a limiting copper pillar 5, a USB infrared camera 6, a ring-shaped electromagnet 7, a rotating guide rail 8, a vertical guide rail 9, a magnetic drive layer 10, an adhesive layer 11, an acrylic (PMMA) rigid waveguide 12, an LED programmable controller 13, 12 infrared light sources 14, and a bracket 15. The LED programmable controller 13 is located outside the vertical guide rail 9 and is connected to the infrared light sources 14 via signal lines to control the infrared light sources 14. The switch and parameter control are provided. The infrared light source 14 is set on the bracket 15. Each LED infrared light source 14 is symmetrically distributed around the acrylic rigid waveguide 12, and the light is uniformly coupled into the acrylic rigid waveguide 12 from the side to meet the total internal reflection phenomenon of the light in the waveguide. This is used to provide sufficient light signal for the optical waveguide to achieve accurate monitoring of the adhesion of wet soft materials. When the optical waveguide comes into contact with the target object being adhered to, the pressure change at the contact interface will cause the refractive index distribution and light transmission characteristics of the optical waveguide to change, thereby causing light signal leakage.The surface of the acrylic rigid waveguide 12 is perpendicular to the optical axis of the USB infrared camera 6, and its leakage light area is within the camera's focal plane or depth of field, enabling the camera to clearly image the leakage light distribution. The camera base 4 is fixedly connected to the sensor housing, and the USB infrared camera 6 is fixedly connected to the camera base 4 via limiting copper pillars 5. The electromagnet 7 is connected to the vertical guide rail 9 via a rotating guide rail 8. The rotating guide rail 8 is responsible for adjusting its horizontal position, and the vertical guide rail 9 is used for adjusting its vertical height, thereby achieving spatial control of the magnetic field direction and intensity. The adhesive layer 11, as a functional layer, and the acrylic rigid waveguide 12, as a substrate layer, together form a composite optical waveguide structure, integrating light transmission and mechanical support. The adhesive layer 11 is tightly bonded to the acrylic rigid waveguide 12 via a bonding method to form a continuous optical interface. The outer surface of the adhesive layer 11 serves as the sensing interface, on which microstructures 16 are provided for optical interaction with the external target or environment. The microstructures 16 are arranged in a gradient pattern, dense in the middle and sparse at the edges. The magnetic drive layer 10 has a hollowed-out design in the middle, forming a magnetic drive ring structure. Simultaneously, the magnetic drive layer 10 employs a gradient concentration design, allowing not only the light leaking from the optical waveguide to pass through but also enabling precise gradient force control. Specifically, the magnetic drive layer uses iron(III) oxide (Fe3O4) nanoparticles as the magnetic functional phase, and polydimethylformamide... PDMS (dimethylsiloxane) serves as a flexible matrix, achieving controllable magnetic response through gradient dispersion and magnetic field orientation processes. The preparation method of the magnetic driving layer is as follows: First, Fe3O4 nanoparticles (50-100 nm in diameter) are surface-modified (using conventional polymer coating methods, forming a polyethylene glycol shell on the particle surface to enhance biocompatibility, dispersion stability, and subsequent functionalization capabilities); then, magnetic PDMS composite materials are prepared according to a gradient concentration design—the edge region uses 5-10% Fe3O4 by mass to ensure flexibility and light transmittance, while the central region increases to 20-30% to enhance magnetic driving force; the PDMS prepolymer polydimethylsiloxane is then combined with a crosslinking agent, hydrosiloxane. After mixing at a ratio of 10:1, Fe3O4 slurry is injected into different areas and circulated using a three-roll mill to ensure uniform dispersion. After vacuum degassing, it is injected into a ring mold. A stepped curing process is adopted during the molding process: first, it is pre-cured at 60℃ for 10 minutes to initially fix the gradient structure, then a 0.5T axial magnetic field is applied to orient the Fe3O4 particles along the magnetic field lines to enhance magnetic anisotropy, and finally, it is completely cured at 80℃ for 2 hours. After demolding, the magnetic drive layer is magnetized by a pulsed magnetic field (3T, 10ms) to increase the remanence to 0.4T. The magnetic drive layer 10 is located below the acrylic rigid waveguide 12, closely attached to the acrylic rigid waveguide 12, and within the range of the magnetic field generated by the electromagnet 7.

[0070] In the aforementioned optical waveguide sensor, the acrylic rigid waveguide 12 is made of polymethyl methacrylate (PMMA), which is mainly used to provide stable mechanical support and serve as the initial injection and transmission path for optical signals. The optical signals coupled in by the external light source are efficiently guided to the adhesion layer 11 through the acrylic rigid waveguide 12. The adhesion layer 11 is made of PDMS (polydimethylsiloxane). PDMS can not only effectively transmit optical signals but also maintain stable performance in a humid environment. The flexibility of PDMS allows it to adapt to the deformation of complex surfaces, ensuring that the optical waveguide will not fail due to excessive deformation during the grasping process. The adhesion layer 11 is prepared by pouring PDMS (prepolymer polydimethylsiloxane / crosslinking agent hydrogen-containing siloxane in a ratio of 10:1) onto a soft rubber mold with microstructures (80mm-120mm), vacuuming to remove air bubbles, and curing in a drying oven at 60°C for 12 hours. The adhesive layer containing microstructures 16 is then demolded.

[0071] The USB infrared camera 6 captures changes in the light signal, enabling accurate detection and analysis of subsequent changes in the light signal caused by factors such as pressure. This allows for precise calculation of the contact area and adhesion strength, achieving high-precision control and real-time feedback of the device's gripping process for wet and soft materials. The rotating guide rail 8 and the vertical guide rail 9 adjust the spatial orientation of the electromagnet 7, thereby changing the magnitude and direction of its magnetic field at the magnetic drive layer 10. The generated magnetic field causes deformation of the magnetic drive layer 10. During the contact process between the adhesion layer 11 and the target object, controlling the magnitude and direction of the magnetic field causes the waveguide adhesion layer 11 to adhere under gradient force, facilitating the removal of air bubbles during the contact process. When detachment is required, due to the gradient arrangement of the microstructure on the adhesion layer 11 (dense in the middle and sparse at the edges), the magnetic field of the magnetic drive ring 7 more easily causes the adhesion layer 11 to curl up, thus achieving detachment from the target object. Meanwhile, the magnetic drive layer 10 adopts a hollow design in the middle to facilitate the transmission of light through the optical waveguide. During the debonding process, the optical waveguide detection mechanism can monitor the state of the adhesion interface in real time. By monitoring the changes in the contact area and adhesion strength of the adhesion interface through the optical waveguide, the system dynamically adjusts the magnetic field parameters of the electromagnet 7 according to the actual adhesion situation, thereby optimizing the debonding effect, avoiding the problems of excessive or insufficient debonding, improving the controllability and accuracy of the debonding process, and ensuring the efficiency and stability of the entire operation process.

[0072] The aforementioned optical waveguide sensor system dynamically adjusts the magnetic field parameters of electromagnet 7 according to the actual adhesion conditions. Specifically, the desired debonding speed v is determined based on the characteristics of the wet, soft material to be treated and the application scenario. d At the same time, set the initial value of k1 (k1 is the debonding speed adjustment coefficient);

[0073] Calculate the initial magnetic field strength B0 and direction B0 using the formula B0 = k1 × F. dθ0 is initially set according to the device structure and the requirements of the debonding direction, and the initial magnetic field strength B0 and magnetic field direction B0 are obtained and applied to the electromagnet 7.

[0074] During the debonding process, the current debonding speed v is monitored in real time using an optical waveguide detection mechanism. current Adjustments are made based on the difference between the monitored current speed and the expected value. If v current <v d B new =B current +k1×(v d -v current If v current >v d B new =B current -k1×(v d -v current ).

[0075] Light enters an optical waveguide through a medium with a refractive index of n1 and propagates within it. The refractive index of the waveguide is n0, the refractive index of the inner medium is also n1, and the refractive index of the outer medium is n2. The incident medium and the inner medium of the waveguide are both air, while the outer medium is water or an object to be adhered to, where n2 > n1. Light propagates in the optical waveguide according to the law of refraction. The incident angle λ0 of the light entering the waveguide must satisfy the following condition:

[0076]

[0077] The effective incident angle range for total internal reflection within the waveguide can be determined by this condition. Then, by adjusting the angle of the light source support 15, the angle at which the light is incident on the waveguide can be changed to keep it within a reasonable angle.

[0078] The aforementioned optical waveguide sensor utilizes enhanced wet adhesion technology. The outer surface of the adhesion layer 11 is provided with gradient-distributed hexagonal prism microstructures 16. When in contact with wet and soft materials, it can effectively utilize surface micro-capillary forces and micro-physical negative pressure to achieve a stable adhesion effect. Because the adhesion layer is made of PDMS material, it has strong adaptability and can significantly improve the adhesion ability to wet and soft materials in complex wet and slippery surface environments. Due to the gradient arrangement of the microstructures, de-adhesion can be achieved relatively easily during the de-adhesion process, effectively reducing energy consumption and the risk of damage to objects.

[0079] Introducing a pit-like design on the surface of a hexagonal prism microstructure significantly improves adhesion and optimizes functionality. Its core advantage lies in the synergistic effect of geometry and surface properties, achieving more efficient capillary force utilization, fluid management, and optimized contact interfaces. Specifically, the arc-shaped recesses of the pit structure and the edges of the hexagonal prisms form a multi-level gradient structure. When the adhesion layer contacts a wet surface, the pits act as liquid storage units, actively adsorbing and fixing the liquid through capillary action, forming a stable micro-liquid bridge network. Simultaneously, these liquid bridges not only enhance local adhesion through surface tension but also guide liquid flow into the gaps between the hexagonal prisms through the directional arrangement of the pits, reducing disordered liquid accumulation at the contact interface and thus preventing adhesion failure due to excessive liquid film thickness. Furthermore, the combination of the pit geometry and the gradient distribution of the hexagonal prisms (high density in the central area, low density at the edges) prioritizes liquid capture and bubble expulsion in the central area during the initial contact phase. Subsequently, the hexagonal prism structure in the edge areas gradually adheres, forming a progressive squeezing effect from the inside out, completely eliminating residual bubbles.

[0080] The hexagonal structure dimensions (such as side length and height) of the microstructure 16 are optimized according to the characteristics of the target surface. The optimization of the hexagonal structure dimensions mainly involves the design of the side length L and the height H. The side length L determines the contact area and distribution density of the hexagonal structure. The optimization formula for the side length L is:

[0081]

[0082] In the formula, F ad γ is the required adhesion force, γ is the interfacial energy, and N is the distribution density of the hexagonal structure (the number of hexagonal structures per unit area). The height H determines the deformation capacity and adaptability of the hexagonal structure; the optimization formula for height H is:

[0083]

[0084] In the formula, E is the elastic modulus of the material, and ΔA is the change in contact area.

[0085] The hexagonal structure achieves optimal adhesion and adaptability when the side length L is in the range of 50-120 μm and the height H is in the range of 70-150 μm. Meanwhile, the distance between microstructures (W), the side length (L) of the hexagonal prism, the height (H) of the hexagonal prism, the width-to-length ratio (W / L), the height-to-length ratio (H / L), and the height-to-width ratio (H / W) all have a certain influence on the adhesion strength. Wet adhesion decreases as the W / L value increases, due to the decrease in the actual contact area between the two planes. The optimal H / L range is 0.7-0.9, within which wet adhesion is significantly improved. The value of H / L affects the wet adhesion caused by prism deformation. When H / W is 1-1.8, wet adhesion increases due to the improved drainage capacity of the connecting channels. Finally, W = 70 μm, H = 80 μm, and L = 90 μm were set. Simultaneously, suction cups with a curvature of 0.8-0.9 can obtain a larger effective contact area than those with other curvatures and exhibit the best switchable adhesion.

[0086] The aforementioned wet soft material adhesion and gripping device based on flexible optical waveguides adopts a two-sided gripping strategy and adjusts the gripping preload in real time during the gripping process.

[0087] An optical waveguide sensor 3 is placed on the electric gripper at the end of the actuator of the UR5 robotic arm 1. A three-axis displacement stage 19 is located below the optical waveguide sensor 3, and a glass slide 18 is fixedly mounted on the top surface of the three-axis displacement stage 19. The target object 17 is placed on the glass slide 18. First, the UR5 robotic arm 1 adjusts its posture so that the two adhesive layers 11 are parallel to the surface of the target object 17. Then, the electric gripper 2 slowly closes. When the two adhesive layers contact the target object, infrared light propagates along the acrylic rigid waveguide 12 and forms a leakage light field at the contact interface. A USB infrared camera 6 captures the light signal, and a computer calculates the contact area and leakage light intensity distribution on both sides in real time. The control system determines whether the current adhesion state is balanced based on the difference in light intensity and the change in contact area on both sides, and adjusts the closing displacement or force output of the electric gripper 2 in real time through a proportional-integral (PI) control algorithm to achieve dynamic control of the preload. The proportional-integral (PI) control algorithm is as follows:

[0088]

[0089] In the formula, e(t) is the error signal, i.e., the deviation between the predetermined value and the actual value of the adhesion area change; KP is the proportional gain; and ki is the integral gain. The magnitude of the preload required for the next adhesion gripping is calculated using the deviation value of the area change rate in a closed loop.

[0090] When the system detects a decrease in light leakage or a reduction in contact area on one side, it determines that the adhesion force on that side is insufficient. It immediately issues a command to slightly increase the clamping force on that side or adjusts the posture via the UR5 robotic arm 1. Simultaneously, it controls the electromagnet 7 to change the direction and intensity of the magnetic field via the rotating guide rail 8 and the vertical guide rail 9, causing deformation of the magnetic drive layer 10 and locally enhancing the adsorption capacity of the adhesion layer 11. If the light intensity on one side is too high, indicating excessive adhesion force, the system weakens the magnetic field or slightly relaxes the gripper pressure to prevent deformation of wet, soft objects. Throughout the process, the leaked light signal serves as real-time feedback, forming a high-speed closed loop of "light signal—control algorithm—gripper action." The preload force can be automatically corrected within millisecond response time, achieving continuous, real-time, and adaptive gripping force control.

[0091] During the de-adhesion stage, the system adjusts the gradient magnetic field of the magnetic drive layer 10 to gradually lift the adhesion layer 11 from the edge, achieving gentle de-adhesion. The USB infrared camera 6 continuously monitors changes in the light signal. When the rate of change of the contact area exceeds a set threshold, the control system automatically adjusts the magnetic field and the gripper opening to ensure smooth and controllable de-adhesion. This control strategy achieves real-time closed-loop adjustment of the preload force throughout the entire process from adhesion contact to handling and de-adhesion, effectively improving the safety, accuracy, and stability of gripping wet and soft objects.

[0092] In summary, the aforementioned wet soft material adhesion and gripping device based on flexible optical waveguides improves mechanical transmission and signal stability through a PMMA / PDMS composite waveguide structure. Based on the optical waveguide leakage principle, it monitors changes in contact area and fluctuations in leakage light intensity in real time. By detecting contact information at the interface through optical waveguide sensors, it provides high-precision pressure feedback information, achieving high-precision control and real-time monitoring of the wet soft material adhesion process. This real-time and precise force feedback mechanism enables the system to dynamically adjust the gripping force, thereby ensuring the stability and reliability of the entire gripping process.

[0093] The optical waveguide sensor utilizes non-contact optical signal transmission to monitor the contact area and adhesion strength in real time, ensuring precise control of the adhesion preload and preventing object damage or grasping failure. Simultaneously, the magnetic control method, through the design of electromagnets and magnetically driven rings, achieves an efficient and controllable de-adhesion process, particularly suitable for scenarios requiring frequent adhesion and de-adhesion. To further enhance adhesion performance, a microstructure 16 with gradient-distributed hexagonal prisms and suction cups is designed. This ensures strong gripping with high adhesion strength in the central region, while the lower adhesion strength at the edges makes the de-adhesion process gentler and consumes less energy, significantly improving the stability and adaptability of adhesion in wet environments. This provides technical support for fields such as robotics and biomedicine.

[0094] Example 2

[0095] The specific operation steps of the wet soft material adhesion and gripping device based on flexible optical waveguide described in Example 1 are as follows:

[0096] I. Equipment Preparation and Initialization

[0097] First, a comprehensive inspection was conducted on the entire wet soft material adhesion and gripping device based on flexible optical waveguides to ensure that all components were securely connected, without any signs of loosening or damage, and that the parameters of each component were set to their default initial state.

[0098] Based on the expected size and characteristics of the target object 17 to be adhered to, adjust the stroke range and accuracy parameters of the triaxial stage 19 to accurately position the slide 18. Place the cleaned slide 18 stably on the top surface of the triaxial stage 19, and use a suitable fixing device (such as a clamp or vacuum adsorption device) to ensure that the slide 18 does not shift during operation.

[0099] For different types of wet and soft materials, appropriate materials for the adhesion layer 11 and parameters for the microstructure 16 are selected. For example, for wet and soft materials with relatively rough surfaces and high viscosity, a microstructure 16 with a high elastic modulus and a large hexagonal structure size (gap of 70 μm, height of 80 μm, and side length of 90 μm) is selected, and the material of the adhesion layer 11 (such as PDMS) is ensured to have uniform thickness and be free of bubbles or impurities to guarantee good light transmission performance and adhesion effect.

[0100] Infrared light source 14 and USB infrared camera 6 are turned on. The brightness, wavelength, and other parameters of infrared light source 14 are calibrated by LED programmable controller 13 to ensure that the light emitted by infrared light source 14 meets the illumination requirements of the optical waveguide without generating excessive noise that would interfere with the image acquisition of USB infrared camera 6. At the same time, the focal length, exposure time, resolution, and other parameters of camera 6 are adjusted to ensure that the image details of the contact interface between the optical waveguide and the target object 17 being adhered to are clearly captured, providing accurate visual information for subsequent adhesion control.

[0101] II. Adhesive Contact of Robotic Arm

[0102] Based on the pre-acquired information on the shape, size, and surface characteristics of the target object to be adhered to, the motion path and initial preload of the robotic arm are planned. If the surface of the target object is relatively soft and easily deformable, such as certain biological tissues, the movement speed of the robotic arm should be appropriately reduced, and the initial preload value should be set at a low level (e.g., 0.1-0.2N) to avoid excessive compression or damage to the object at the moment of contact.

[0103] The robotic arm is controlled to slowly move the adhesive layer 11 toward the target object 17. As it approaches the target object, the force feedback sensor and proximity sensor of the UR5 robotic arm 1 are activated to monitor the distance and force between the end effector of the robotic arm and the target object 17 in real time. When the proximity sensor detects that the distance between the adhesive layer 11 and the target object 17 reaches a preset proximity threshold (e.g., 1-2 mm), the UR5 robotic arm 1 switches to a low-speed, high-precision control mode to ensure accurate contact.

[0104] Once the adhesive layer 11 comes into contact with the target object 17, the force feedback sensor monitors the contact force in real time and transmits the data to the control system. The control system dynamically adjusts the preload force of the robotic arm based on a preset contact force threshold and the characteristics of the target object. For example, if the contact force increases rapidly within a short period and exceeds the expected safety threshold, the control system will immediately reduce the driving force of the robotic arm, thus reducing the preload force. Conversely, if the contact force increases slowly and does not reach the minimum value required for effective adhesion, the control system will appropriately increase the driving force of the robotic arm to promote sufficient contact between the adhesive layer 11 and the target object, ensuring the stability and reliability of the adhesion process.

[0105] III. Optical Waveguide Detection of Adhesion Interface and Event-Driven Control Figure 6 )

[0106] The infrared light source 14, under the precise control of the LED programmable controller 13, continuously and stably emits light signals of a specific wavelength and intensity. The light signals are transmitted to the area where the optical waveguide is located, providing a uniform and stable illumination environment for the optical waveguide and ensuring that the optical waveguide can accurately respond to changes in the contact interface.

[0107] When the acrylic rigid waveguide 12 comes into contact with the target object 17, the pressure change at the contact interface alters the light transmission characteristics, resulting in light signal leakage. The USB infrared camera 6 captures the changes in the leaked light in real time at high speed and high resolution, and transmits the image data to the image processing chip. The image processing chip performs real-time analysis and processing on the images acquired by the camera. First, an image thresholding algorithm is used to separate the leaked light area from the background area, extracting effective adhesion interface image information. Then, an edge detection algorithm (such as the Canny edge detection algorithm) is used to accurately identify the position and shape changes of the contact edge between the optical waveguide and the target object, calculating the real-time value of the contact area.

[0108] Simultaneously, based on the changes in light intensity distribution, the current adhesion strength is estimated using a pre-established light intensity-adhesion force model. This model accurately reflects the relationship between changes in light signal and adhesion force. For example, if a certain percentage decrease in light intensity is detected in a specific area, the model can be used to calculate the range of increase or decrease in adhesion force in that area. Furthermore, the optical waveguide sensor monitors the size of the adhesive contact area in real time and calculates the debonding rate through differentiation, comparing the debonding rate with a preset threshold.

[0109] If the de-adhesion rate exceeds the threshold, it indicates that the de-adhesion is too rapid, and the preload force needs to be increased to enhance gripping stability. Set a series of adhesion event trigger conditions, such as when the rate of change of the contact area exceeds a preset threshold (e.g., 10% / s) within a short period, or when the change in adhesion strength exceeds a safe range (e.g., ±0.5 N / cm). 2 When a critical adhesion event occurs, the system immediately initiates the corresponding control strategy adjustment procedure. The system calculates the debonding rate deviation e(t) and outputs the preload increment ΔF through the PI controller. The robotic arm adjusts its gripping state based on the updated preload information and continues to monitor the debonding rate, forming a closed-loop control.

[0110] If the debonding rate and preload change satisfy the stable grasping condition (i.e., the system has converged) within N consecutive control cycles, it indicates that the current preload is sufficient for stable grasping, and the grasping transfer can be executed and the process terminated. During this process, the force sensor monitors the preload in real time. If an abnormality is detected (such as excessive or sudden force), the control process is immediately interrupted to prevent damage to the object or loss of system control.

[0111] IV. Grabbing, Transfer, and De-adhesion Operations

[0112] During continuous monitoring and adjustment of the adhesion process, once the adhesion and gripping conditions are met (e.g., the contact area stabilizes within a certain range and the adhesion strength reaches a minimum sufficient for safe gripping) as determined by optical waveguide detection and image analysis, the control system sends a gripping command to the robotic arm. The robotic arm smoothly grips the target object and transfers it to the designated location according to a preset trajectory and speed. During the transfer, the robotic arm's motion control should consider the inertia and center of gravity changes of the target object to ensure that the object does not shake or detach.

[0113] Once the target object reaches the designated position, the detachment process is initiated. Electromagnet 7 generates a magnetic field based on preset initial magnetic field strength and direction parameters. This magnetic field acts on the magnetic drive layer 10, causing the magnetic drive layer (magnetic drive ring) to deform. Since the magnetic drive layer 10 is tightly connected to the adhesion layer 11, the deformation of the magnetic drive layer 10 will cause the adhesion layer 11 to undergo an edge lifting and detachment operation.

[0114] During the debonding process, the optical waveguide feedback mechanism continuously monitors the state of the adhesion interface in real time. Camera 6 continuously captures images of changes in leaked light, and the image processing chip analyzes the images to obtain real-time information on changes in contact area and adhesion strength. The system dynamically adjusts the magnetic field parameters of electromagnet 7 based on this feedback information. For example, if it is found that the adhesion force on one side decreases too slowly, resulting in uneven debonding, the system will appropriately adjust the direction of the magnetic field to subject that side to a stronger magnetic field, promoting debonding; if the overall adhesion force decreases too quickly, posing a risk of excessive debonding, the system will reduce the magnetic field strength to slow down the debonding speed, ensuring a smooth and controllable debonding process.

[0115] V. End of Operation

[0116] Once the adhesive layer 11 has completely detached from the target object, the robotic arm moves the adhesive mechanism to its initial position. At the same time, the system records relevant data for this operation, including the light signal change curve, the history of adhesion strength change, the debonding time and effect, etc., to provide a basis for subsequent operation optimization and data analysis.

[0117] The aforementioned flexible optical waveguide-based wet soft material adhesion and gripping device can more effectively realize an event-driven, controllable, and reversible adhesion strategy based on optical waveguide sensing, meeting the requirements for high-precision, adaptive adhesion control of wet soft materials. In practical applications, the parameters and methods of each step can be optimized and adjusted according to the specific scenario and the characteristics of the target object to achieve the best operational results.

[0118] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An optical waveguide sensor, characterized by: The application relates to a sensor shell which is internally provided with a camera base, a limiting copper column, a USB infrared camera, an electromagnet, a rotating guide rail, a vertical guide rail, a magnetic drive layer, an acrylic hard waveguide, an LED programmable controller, an infrared light source and a support, the LED programmable controller is arranged on the outer side of the vertical guide rail and is connected with the infrared light source through a signal line, the infrared light source is arranged on the support and is used for adjusting the angle of light entering the acrylic hard waveguide, the surface of the acrylic hard waveguide is perpendicular to the optical axis of the USB infrared camera and the leakage light area of the acrylic hard waveguide is located in the camera focal plane or the depth of field range, the camera base is fixedly connected with the sensor shell, the USB infrared camera is fixedly connected with the camera base through the limiting copper column, the acrylic hard waveguide is provided with a microstructure, the electromagnet is connected with the vertical guide rail through the rotating guide rail, the magnetic drive layer is arranged below the acrylic hard waveguide, is closely combined with the acrylic hard waveguide and is located in the action range of the magnetic field generated by the electromagnet.

2. The optical waveguide sensor of claim 1, wherein: The number of the infrared light sources is 12, and each LED infrared light source is symmetrically distributed around the acrylic hard waveguide and uniformly couples light into the acrylic hard waveguide from the side.

3. The optical waveguide sensor of claim 1, wherein: The application further comprises an adhesive layer which, together with the acrylic hard waveguide, forms a composite optical waveguide structure.

4. The optical waveguide sensor of claim 3, wherein: The material of the acrylic hard waveguide is a hard transparent material with a first refractive index, is used for providing stable mechanical support and serving as an initial injection and transmission passage of optical signals, and the light signal coupled in from the outside is efficiently guided to the adhesive layer through the acrylic hard waveguide; the material of the adhesive layer is a flexible transparent material with a second refractive index, and the second refractive index is generally slightly lower than the first refractive index; the adhesive layer is closely combined with the acrylic hard waveguide in a pasting mode, and forms a continuous optical interface.

5. The optical waveguide sensor of claim 3, wherein: The outer surface of the adhesive layer is a sensing interface which is provided with a microstructure and is used for optical interaction with an external target or environment to be measured; preferably, the microstructure on the adhesive layer is arranged in a gradient arrangement; further preferably, the material of the adhesive layer is polydimethylsiloxane.

6. The optical waveguide sensor of claim 1, wherein: The magnetic drive layer is designed in a hollow structure and is a magnetic drive ring structure; preferably, the magnetic drive layer takes ferroferric oxide nanoparticles as a magnetic functional phase and polydimethylsiloxane as a flexible matrix, and realizes controllable magnetic response through a gradient dispersion and magnetic field orientation process.

7. The optical waveguide sensor of claim 1, wherein: The system dynamically adjusts the magnetic field parameters of the electromagnet according to the actual adhesion, and the specific method is as follows: according to the characteristics of the wet soft matter to be treated and the application scene, the expected debonding speed v is determined d At the same time, the initial value of k1 is set. Calculating initial magnetic field strength B0 and direction B0: according to the formula B0=k1xF d θ0 is preliminarily set according to the device structure and the debonding direction requirement, the initial magnetic field strength B0 and the magnetic field direction B0 are obtained, and are applied to the electromagnet; In the debonding process, the current debonding speed v is monitored in real time by using the light waveguide detection mechanism current , and the adjustment is made according to the difference between the monitored current speed and the expected value, if v current <v d , B new =B current +k1×(v d -v current ), if v current >v d , B new =B current -k1×(v d -v current ) Preferably, light is emitted from a medium with a refractive index of n1 into an optical waveguide, propagates in the optical waveguide, the refractive index of the optical waveguide is n0, the refractive index of the inside of the optical waveguide is also n1, and the refractive index of the outside of the optical waveguide is n2; the incident medium and the inside medium of the waveguide are both air, the outside medium is water or an object to be adhered, and n2>n1; the light propagating in the optical waveguide obeys the refraction law, and the incident angle theta0 of the incident light of the optical waveguide should satisfy the following condition: The effective incident angle range of total reflection in the waveguide is solved through the condition, and the angle of light entering the waveguide is changed by adjusting the angle of the light source support so that the light is within a reasonable angle. Preferably, the hexagonal structure size of the microstructure is optimized according to the characteristics of the target surface, and the optimization formula of the side length L is: In the formula, F ad γ is the required adhesion force, γ is the interfacial energy, and N is the distribution density of the hexagonal structure. The optimization formula of the height H is: Wherein E is the elastic modulus of the material, and ΔA is the change amount of the contact area.

8. A flexible optical waveguide based wet soft matter adhesion gripping device, characterized by: The device comprises a UR5 mechanical arm, an electric gripper, and an optical waveguide sensor according to any one of claims 1-7, the electric gripper is fixed at the end of the UR5 mechanical arm, and the optical waveguide sensor is arranged on the electric gripper through the sensor shell thereof.

9. The method of claim 8, wherein the method further comprises: determining a position of the flexible optical waveguide based on the detected position of the object; and adjusting the position of the object based on the determined position of the flexible optical waveguide. The specific process is as follows: (1) Start preparation: confirm that all parts of the device are correctly installed and in the initial state, place the adhered target object on the glass slide, and fix the glass slide on the top surface of the three-week displacement table; (2) The mechanical arm adheres to contact with a set preload: by controlling the UR5 mechanical arm, the adhesive layer of the optical waveguide sensor moves and contacts the adhered target object, an initial preload is set according to the property information of the adhered target object, and the adhering process is started; (3) The optical waveguide detects the adhesion interface information: the infrared light source emits light under the control of the LED programmable controller, and the optical signal is transmitted to the area where the optical waveguide sensor is located to provide illumination for the optical waveguide sensor; after the adhesive layer contacts the adhered target object, the pressure change of the contact interface causes the refractive index distribution and the light transmission characteristics of the optical waveguide to change, resulting in light signal leakage, and the USB infrared camera captures the change of the leaked light; (4) Determine whether the adhesion grabbing condition is met: according to the light signal change captured by the USB infrared camera, the contact area and the adhesion strength are accurately calculated, and it is determined whether the adhesion grabbing condition is met, if not, return to step (2) and increase the preload, continue to monitor and adjust; if yes, proceed to the next step; (5) Grabbing, transferring and debonding: after the adhesion grabbing condition is met, the adhered target object is grabbed and transferred to the specified target position by the UR5 mechanical arm, and debonding is required after reaching the specified position; the spatial pose of the electromagnet is adjusted through the rotating guide rail / vertical guide rail, the magnetic field generated by the electromagnet acts on the magnetic driven layer to cause it to deform, and the adhesive layer is caused to warp and debond; during the debonding process, the optical waveguide sensor monitors the adhesion interface state in real time, the system dynamically adjusts the magnetic field parameters of the electromagnet according to the actual adhesion condition, optimizes the debonding effect, and ensures smooth debonding; (6) End operation: after debonding is completed, the device returns to the initial state and waits for the next operation instruction.

10. The method of claim 9, wherein: In step (4), an event-driven reversible adhesion strategy is adopted, when the adhesive layer contacts and adheres to the adhered target object, if the contact area suddenly decreases in a short time, it indicates that the object surface or the adhesion strength has sharply decayed; at this time, if the contact area change rate exceeds the preset threshold value, that is, the debonding rate is greater than the set threshold value, the system should determine that this adhesion does not meet the stable grabbing condition, and the preload should be increased for adhesion grabbing again; The event-driven reversible adhesion strategy uses light signal intensity change, after the adhesive layer contacts the adhered target object, the light signal intensity suddenly decreases due to the pressure leakage light on the surface of the adhesive layer; when the change rate of the light signal intensity exceeds the preset threshold value, the preload is increased for adhesion grabbing again at this time; Further preferably, the leakage light image collected by the entire optical waveguide sensor and the computer processing algorithm for the image constitute a dynamic feedback control system together, the core of the dynamic feedback control system is to adjust the size of the preload by real-time monitoring of the adhesion interface state to form a closed-loop control, wherein the acrylic hard waveguide, infrared light source and USB infrared camera constitute a sensing layer to capture the change of leakage light intensity for the optical waveguide sensor; the decision layer determines whether to trigger the control action by the proportional-integral control algorithm for the event-driven strategy, that is, whether the debonding rate is greater than the set threshold; the UR5 mechanical arm, electric clamping jaw, rotating guide rail and vertical guide rail constitute the execution layer to adjust the preload contact for the mechanical arm; the proportional-integral control algorithm is: In the formula, e(t) is the error signal, that is, the deviation of the adhesion area change between the predetermined value and the actual value, KP is the proportional gain, and ki is the integral gain. The deviation value of the area change rate is closed-loop calculated to increase the preload size required for the next adhesion grabbing; Further preferably, the bending of the adhesion layer is controlled by magnetic drive to realize an efficient bubble discharge mechanism: when the optical waveguide adhesion layer contacts the adhered target object, the magnetic drive layer deforms under the action of the magnetic field, driving the adhesion layer to produce gradient bending. This bending makes the adhesion layer gradually fit the surface of the object from the center to the edge, forming a squeezing effect from the inside to the outside, so as to gradually discharge the bubbles between the contact interfaces; the initial fitting of the central region ensures that the bubbles will not be trapped in the center, and the gradual fitting of the edge region guides the bubbles to move outward and finally discharge; Further preferably, the optical waveguide sensor is arranged on the electric clamping jaw to realize the grabbing mode of the wet soft material on both sides by opening and closing the clamping jaw; in the initial state, the mechanical arm adjusts the angle to make the optical waveguide adhesion layer on both sides fit the surface of the target object, and the microstructure forms stable adhesion by using capillary force and negative pressure effect; the optical waveguide sensor monitors the adhesion force change of the contact interface on both sides in real time and feeds back the data to the control system; the control system including the UR5 mechanical arm, electric clamping jaw, rotating guide rail and vertical guide rail adjusts the clamping force of the mechanical jaw in real time according to the feedback information of the optical waveguide monitoring interface, ensures the stability in the grabbing process, and avoids excessive force to damage the object; after the grabbing is completed, the optical waveguide adhesion layer is warped by adjusting the opening and closing degree of the mechanical jaw and combining the magnetic control mode to realize the progressive debonding from the outside to the inside, thereby reducing the damage to the object.

Images