Intelligent miniature clamp holder and photomagnetic combined regulation miniature memory clamping jaw

Abstract

The invention belongs to the field of flexible micro robots, and particularly relates to an intelligent micro clamp holder and an optomagnetic combined regulation and control micro memory clamping jaw. The intelligent miniature clamp holder comprises a memory clamping jaw, an optical signal generator, a magnetic field generating device and a controller. The memory clamping jaw is a miniature bionic jaw capable of freely changing the form of the memory clamping jaw under combined driving of an optical signal and a magnetic signal. And the other components form related components capable of generating specified optical signals and magnetic signals according to requirements. The memory clamping jaw comprises a base, a plurality of bionic fingers and an optical fiber. The bionic finger is prepared from a shape memory polymer doped with permanent magnet particles. Each bionic finger in the memory clamping jaw is solidified and formed in an upright state and is magnetized after being shaped to be in a preset folded state under the condition that the temperature is higher than the glass transition temperature, and therefore double-state transition can be achieved. The problems that an existing clamping robot based on SMP is generally insufficient in flexibility and large in operation difficulty are solved.

Description

Technical Field

[0001] The present invention belongs to the field of flexible micro-robots, and in particular relates to an intelligent micro-gripper, a micro-memory gripper controlled by light and magnetism, and a preparation method of the memory gripper. Background Art

[0002] The gripping robot based on shape memory polymer (SMP) is a cutting-edge micro-flexible robot. This type of robot uses the memory recovery characteristics of SMP to change its shape under external stimulation (such as heat, electricity, magnetism, light, etc.) to achieve motion control. Since this type of robot does not need to be controlled by electric wire, it can achieve extreme miniaturization and has broad application prospects in aerospace, biomedicine, 4D printing, flexible microelectronics and other fields.

[0003] The driving technologies of traditional SMP robots mainly include electrothermal drive, photothermal drive technology and magnetic drive. Among them, the electrothermal drive technology is to form a heating electrode in the shape memory polymer matrix, and then heat the material under the condition of power on to achieve dynamic control. Photothermal drive technology usually uses electromagnetic waves such as infrared to irradiate shape memory polymers, and the shape memory polymers absorb the infrared radiation energy and convert it into heat energy, thereby achieving self-temperature regulation and shape control. Magnetic drive technology makes the robot parts magnetically conductive, and then controls their execution of actions through dynamic magnetic fields.

[0004] In actual application, the above three driving technologies are usually unable to control the gripping robot over long distances. The control process may be limited by structure and space, and it is impossible to accurately and differentially control different structures in the gripping robot. The operation flexibility is poor and the practical value is limited. Summary of the invention

[0005] In order to solve the problems of insufficient flexibility and greater difficulty in operation commonly existing in existing SMP-based gripping robots, the present invention provides an intelligent micro gripper, a micro memory gripper with optical and magnetic combined control, and a method for preparing the memory gripper.

[0006] The technical solution provided by the present invention is:

[0007] An intelligent micro-gripper comprises a memory gripper, an optical signal generator, a magnetic field generating device and a controller.

[0008] The memory gripper includes a base, a plurality of bionic fingers fixedly connected to the surface of the base, and an optical fiber embedded in the base or each bionic finger. The bionic finger is made of a shape memory polymer doped with permanent magnet particles; each bionic finger is solidified in an upright state, and is shaped into a preset retracted shape under conditions above the glass transition temperature and then magnetized. The bionic finger has the characteristics of remaining bent under a specified temperature and magnetic field environment and returning to an upright position after the magnetic field is removed; the optical fiber is used to transmit an optical signal that can regulate the temperature of the bionic finger.

[0009] The optical signal generator includes a light source and a multi-channel optical switch; the light source is used to generate multi-channel optical signals and output them through multiple independent output ports. The optical switch is used to control the on and off of each output port; each output port of the light source is connected to the base of the memory gripper or the optical fiber on the bionic finger.

[0010] The magnetic field generating device is used to generate a directional magnetic field that can drive the clamping claw to bend to a preset shape. The controller is electrically connected to the optical signal generator and the magnetic field generating device. The controller is used to control the optical signal generator to emit an optical signal to a specified bionic finger to achieve directional heating of the bionic claw, and to control the magnetic field generating device to generate or cancel a magnetic field in a specified area, thereby using the magnetic field to drive the bionic claw above the glass transition temperature to change its shape, so as to achieve a specified clamping or releasing action.

[0011] As a further improvement of the present invention, when the intelligent micro-gripper performs a clamping action, the control logic of the controller is as follows:

[0012] (1) Determine the expected shape of each bionic finger according to the preset gripping posture.

[0013] The shapes of the bionic fingers include upright and bent, and each bionic finger remains upright in the initial state.

[0014] (2) Sending instructions to the optical signal generator to emit optical signals to each bionic finger whose expected shape is bending, so that it is transformed from the glass state to the rubber state.

[0015] (3) An opening command is issued to the magnetic field generating device to generate a directional magnetic field of a specified direction and intensity at the position of the memory gripper, so that each bionic finger in the rubber state bends.

[0016] (4) Sending a command to the optical signal generator to stop emitting the optical signal, so that the bent bionic finger returns to the glass state from the rubber state.

[0017] (5) Send a closing command to the magnetic field generating device so that the position of the memory clamp is restored to a non-magnetic field environment; at this time, the memory clamp is in a preset clamping posture.

[0018] As a further improvement of the present invention, when the intelligent micro-gripper performs a release action, the control logic of the controller is as follows:

[0019] (1) Determine the expected shape of each bionic finger according to the preset release posture.

[0020] (2) Sending instructions to the optical signal generator to emit optical signals to each bionic finger whose shape changes from bending to upright, so that it changes from the glass state to the rubber state and returns to upright.

[0021] (3) Sending a command to the optical signal generator to stop emitting the optical signal, so that the bionic finger returns from the rubber state to the glass state; at this time, the memory gripper completes the release of the clamped object.

[0022] As a further improvement of the present invention, the controller pre-stores the heating curve and recovery curve of the bionic finger at different infrared powers. The controller queries the heating curve or recovery curve according to the current infrared power and heating time, and then identifies the current phase of the bionic finger.

[0023] As a further improvement of the present invention, each bionic finger of the intelligent micro gripper is also provided with a micro temperature sensor, which is electrically connected to the controller via a signal cable. The controller detects the real-time temperature of each bionic finger through the temperature sensor, and then identifies the current phase of the bionic finger.

[0024] As a further improvement of the present invention, the intelligent micro gripper further includes a multi-degree-of-freedom mechanical arm, the memory gripper is mounted at the end of the mechanical arm, and the mechanical arm is used to drive the memory gripper to move in space. The mechanical arm is electrically connected to a controller, and the controller is used to control the motion trajectory of the mechanical arm.

[0025] The present invention also includes a micro memory gripper with combined optical and magnetic control, which includes a base, a plurality of bionic fingers fixedly connected to the surface of the base, and an optical fiber embedded in the base or each bionic finger. The bionic fingers are made of shape memory polymers doped with permanent magnet particles. Each bionic finger is solidified in an upright state, and is magnetized after being shaped into a preset retracted shape under conditions above the glass transition temperature. The bionic fingers have the characteristics of remaining bent under a specified temperature and magnetic field environment and returning to an upright state after the magnetic field is removed; the optical fiber is used to transmit an optical signal that can regulate the temperature of the bionic fingers.

[0026] As a further improvement of the present invention, the permanent magnet particles are made of neodymium iron boron powder, the shape memory polymer is made of epoxy resin and curing agent in a mass ratio of 3:1, and the doping amount of the permanent magnet particles in the material for preparing the bionic finger is 30-65wt%.

[0027] As a further improvement of the present invention, the bionic fingers are distributed in a ring shape on the base, and each bionic finger has a diameter of 120 μm, a height of 1200 μm, and a spacing of 800 μm.

[0028] The present invention also includes a method for preparing a memory clamp, which is used to prepare the aforementioned optical-magnetic combined control micro memory clamp, and the preparation method includes the following steps:

[0029] 1. Mold preparation

[0030] A mold with a groove on the surface is prepared by using silicone material, and the groove is consistent with the shape of the base in the memory clamp.

[0031] A plurality of finger-shaped grooves that match the shape and spatial distribution of each bionic finger in the memory gripper are processed in the groove of the mold by a femtosecond laser processing system.

[0032] 2. Curing and molding

[0033] The monomers of the shape memory polymer and the permanent magnet particles are mixed in a preset ratio and vacuum defoamed to obtain material one; the monomers of the shape memory polymer are mixed in a preset ratio and vacuum defoamed to obtain material two.

[0034] The material is injected into the mold to fill the finger grooves, and an optical fiber and / or a temperature sensor are pre-embedded in each finger groove; after scraping off the excess material, the first curing is performed under the specified curing conditions.

[0035] Material 2 is injected into the mold to fill the groove, and then a second curing is performed under specified curing conditions; demolding is performed after the second curing is completed.

[0036] 3. Shaping and magnetization

[0037] The demoulded product is heated to a state higher than the glass transition temperature Tg of the material, and then each bionic finger is bent into a preset shape; and the product is magnetized by a strong magnetic field under forced conditions; thereby obtaining the desired memory gripper.

[0038] The technical solution provided by the present invention has the following beneficial effects:

[0039] The present invention uses a shape memory polymer doped with permanent magnet particles to manufacture a memory gripper, and magnetizes the bionic finger after plastic surgery, so that the memory gripper can be freely switched between the gripping action and the releasing action of a human hand under the joint control of infrared light and magnetic field. The solution of the present invention overcomes the difficulty of miniaturization of the soft gripper.

[0040] Different from the traditional restrained clamp, the present invention realizes the directional transmission of the light signal emitted by the light source through the optical fiber integrated into the memory clamp, and then directionally heats the bionic finger, so that the different bionic fingers in the memory clamp can be deformed as needed, thereby realizing more precise manipulation and completing more complex clamping actions.

[0041] The present invention also provides a preparation method of a memory gripper based on the combination of femtosecond laser processing technology and magnetic nanoparticle doped SMP template transfer technology, thereby reducing the manufacturing cost of the intelligent micro gripper, laying a foundation for the market application of the solution.

[0042] The micromanipulator integrated on the optical fiber can be used to manipulate micro-matter in challenging space environments and lightless environments, relying on the soft and slender characteristics of the optical fiber. And the prepared memory gripper, relying on the fine structure of the bionic finger, can be used to non-destructively grasp, transfer and release fragile micro-arthropods (which are easily damaged by tweezers or adhesion grasping). The preparation of micromanipulators and the research on the realization of micro-object manipulation are of great significance to the development of biology, optics, electromechanics and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the intelligent micro-gripper provided in Example 1 of the present invention.

[0044] Figure 2 This is a schematic diagram of the structure of the memory clamp provided in Example 1 of the present invention.

[0045] Figure 3 The diagram is a comparison of the principle and the actual object of the memory claw in Example 1 of the present invention realizing the shape transformation under the joint drive of optical and magnetic signals.

[0046] Figure 4 In Example 1 of the present invention, a schematic diagram of an intelligent micro-gripper including a robotic arm is provided.

[0047] Figure 5 This is a schematic diagram of the memory clamp in Embodiment 2 of the present invention realizing different clamping actions.

[0048] Figure 6 This is a manufacturing flow chart of the memory clamp in Example 2 of the present invention.

[0049] Figure 7 This is a graph showing the relationship between the doping concentration of NdFeB particles and the bending angle of the microcolumns in the test experiment.

[0050] Figure 8 This is a graph showing the relationship between the aspect ratio of the microcolumn and the bending angle of the microcolumn in the test experiment.

[0051] Fig. 9This is a graph showing the relationship between the magnetic induction intensity of the driving magnetic field and the bending angle of the micropillar in the test experiment.

[0052] Fig.10 This is the stability curve of the memory gripper under multiple rounds of cyclic bending recovery in the test experiment.

[0053] Fig.11 The principle and actual comparison diagram of the memory gripper to grasp and transfer the target object in the test experiment

[0054] Fig.12 This is a graph of the temperature change of the memory clamp under laser signal at different doping concentrations in the test experiment.

[0055] Fig.13 This is a comparison chart of the heating effect of the memory gripper under different laser power conditions in the test experiment.

[0056] Fig.14 This is a comparison chart of the heating effect of the memory gripper under different micro-pillar spacing conditions in the test experiment.

[0057] Fig.15 An example diagram of the memory gripper being used to grasp and transfer a spherical target in a test experiment.

[0058] Fig.16 This is a case diagram of the memory gripper being used to grasp and transfer a target object under light-shielded conditions in a test experiment.

[0059] Fig.17 This is an example of a memory gripper being used to grasp and transfer objects inside a pipe in a test experiment.

[0060] Fig.18 An example of a memory gripper being used to grasp and transfer a living object in a test experiment. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0062] Example 1

[0063] This embodiment provides an intelligent micro-gripper, such as Figure 1As shown, it includes: a memory gripper, an optical signal generator, a magnetic field generating device and a controller. Among them, the memory gripper is a micro bionic gripper that can freely transform its own shape under the joint drive of optical signals and magnetic signals. The optical signal generator, the magnetic field generating device and the controller together constitute related components that can generate specified optical signals and magnetic signals as needed, thereby controlling the shape of the memory gripper. The memory gripper in the intelligent micro gripper of this embodiment can be designed as a micron-level structure, thereby realizing flexible grasping and releasing of a variety of micron-level targets.

[0064] like Figure 2 As shown, the memory gripper in this embodiment includes a base, a plurality of bionic fingers and an optical fiber. The bionic finger is fixedly connected to the surface of the base, and one end of each optical fiber in the optical fiber bundle is respectively embedded in the base or each bionic finger in the memory gripper. In this embodiment, the optical fiber bundle is used to transmit an optical signal capable of regulating the temperature of the bionic finger. The bionic finger provided in this embodiment is prepared from a shape memory polymer doped with permanent magnet particles. Each bionic finger in the memory gripper in this embodiment is solidified in an upright state, and is magnetized after being shaped into a preset retracted shape under conditions above the glass transition temperature.

[0065] The preparation materials of the bionic fingers in the memory clamp of this embodiment use shape memory polymers and permanent magnet particles, so each bionic finger has both thermal response characteristics and magnetic response characteristics. Among them, the thermal response characteristic refers to: the main material of the bionic finger provided in this embodiment is a shape memory polymer, so it has the ability to automatically restore the original shape in a state higher than the glass transition temperature TG. Specifically, the bionic finger in the memory clamp of this embodiment is in a rubber state in a state higher than the glass transition temperature TG of the shape memory polymer. In this state, the entire bionic finger structure is soft and can be restored to its initial shape after solidification, as well as deformed by external force. In a state lower than the glass transition temperature TG of the shape memory polymer, the bionic finger is in a glass state and can stably maintain the shape before "cooling". The texture of the cooled bionic finger is hard and difficult to deform under the action of external force.

[0066] The magnetic response characteristic refers to: the bionic finger of this embodiment is magnetized after being shaped into a preset retracted shape. Therefore, in the rubber state, if the memory clamp is placed in a directional magnetic field of a specified direction and intensity, the bionic finger will remain in the retracted shape before magnetization under the action of the magnetic force on the permanent magnet particles after a large number of magnetization inside. When the memory clamp is in a non-magnetic field environment, each permanent magnet particle will not be subjected to a similar magnetic force. At this time, the bionic finger will only show thermal response characteristics. It should be supplemented that: in the glass state, the bionic finger in the memory clamp in this embodiment is hard in texture, so even if it is placed in a directional magnetic field, the bionic finger will not bend to the retracted shape before magnetization.

[0067] In summary, the bionic finger in the memory gripper provided in this embodiment has the characteristics of remaining bent under a specified temperature (higher than the glass transition temperature of the material) and magnetic field environment (same direction as the strong magnetic field used during magnetization) and restoring uprightness after the magnetic field is removed. Specifically, under different temperature and magnetic field conditions, the morphological changes of the bionic finger in the embodiment are shown in the following table:

[0068] Table 1: The morphology of bionic fingers at different temperatures and magnetic fields

[0069]

[0070] From Table 1, it can be seen that by adjusting the temperature of the memory gripper and the magnetic field environment in which it is located, the shape of each bionic finger can be adjusted, thereby achieving actions similar to grasping (i.e., each bionic finger is retracted) and releasing (i.e., each bionic finger remains upright) of a mechanical gripper.

[0071] In the solution of this embodiment, the form of the memory clamp and the bionic finger is not limited. In a typical solution, a clamp-shaped memory clamp including two bionic fingers can be designed, or a four-finger clamp including four symmetrically arranged bionic fingers can be used. It can even be designed as a five-finger clamp that mimics the human palm.

[0072] Existing photothermal-driven SMP gripping robots generally choose to irradiate the memory gripper with a light source, thereby changing the temperature of the memory gripper to achieve the purpose of regulating the shape of the memory gripper. However, this method of direct irradiation with a light source has two disadvantages: First, the direct irradiation method cannot only synchronously heat up all bionic fingers in the memory gripper, and directionally regulate different bionic fingers. And the irradiation process is easily blocked by other structures in the actual application scenario. Second, in the process of miniaturizing the memory gripper, it is difficult to miniaturize the light source while ensuring power. Therefore, in some specific cavities and narrow internal spaces of structures, the light source is placed synchronously with the memory gripper, making it difficult to achieve radiation and temperature control of the memory gripper.

[0073] In this embodiment, the above two major problems are overcome by implanting optical fibers in the bionic fingers of the memory gripper and electrically connecting the optical fibers to the signal generator. Specifically, the optical signal generator used in this embodiment includes a light source and a multi-channel optical switch. The light source is used to generate multi-channel optical signals and output them to the outside through multiple independent output ports. The optical switch is used to control the on and off of each output port. The output ports of the light source correspond to the bionic fingers in the memory gripper one by one, and each output port is connected to an optical fiber on one of the bionic fingers in the memory gripper.

[0074] After using the optical signal generator of this embodiment, when a bionic finger in the memory gripper needs to be heated to achieve action control, the light source can be turned on first, and then the optical switch of the corresponding channel can be turned on. At this time, the optical signal emitted by the light source is directly transmitted to the designated bionic finger through the optical fiber, penetrates the bionic finger and is fully absorbed. The internal molecules and atoms of the bionic finger material "resonate" after the optical signal - generating strong vibration and rotation, thereby increasing the temperature of the material and achieving the purpose of heating.

[0075] It can be seen that this embodiment transmits the light signal in a directional manner through the optical fiber, thereby separating the light source from the memory gripper. In practical applications, the optical fiber of this embodiment can be bent and can reach a deeper hole or a narrow enclosed space with poor lighting conditions together with the memory gripper. This overcomes the limitation that the existing photothermal SMP robot cannot be applied to specific scenarios.

[0076] In addition, it is necessary to additionally explain that: the above content of this embodiment introduces a solution of directly transmitting the optical signal output by the light source to each bionic finger through multiple optical fibers to realize directional heating of the bionic finger. In other embodiments, it is assumed that the structural size of the bionic finger is extremely small, and it is difficult to implant optical fibers in the end face of each bionic finger for directional transmission of the optical signal. It is also possible to use only one optical fiber, and implant the end of the optical fiber into the base of the memory gripper (the scale of the base is obviously larger than the bionic finger connected thereto), and the optical signal transmitted by the optical fiber heats all the bionic fingers connected to the base at the same time, so as to realize morphological control of all bionic fingers. In the above two optical fiber installation methods, although the latter is not as fine as the former in terms of control, it can also realize morphological control of the bionic finger to a certain extent.

[0077] In the existing magnetically driven SMP gripping robot solutions, technicians mostly modify the bionic fingers with ferromagnetic materials, and then use a differentially distributed special magnetic field to apply attractive or repulsive forces to the bionic fingers doped with ferromagnetic materials to control the bionic fingers to deform to a specified side. Although this control method is effective, it requires high control of parameters such as the direction, intensity, and spatial distribution of the manipulated magnetic field. It is difficult to implement in actual applications and the application cost is very high.

[0078] In the present embodiment, a completely new strategy is adopted to realize magnetic regulation of the shape of the memory jaws. Specifically, in the present embodiment, the bionic fingers of the memory jaws are mixed with unmagnetized permanent magnet materials. In the post-processing of the memory jaws, each bionic finger in the memory jaws is first solidified in an upright state. The solidified shape is the initial shape of the memory jaws; in the absence of external force and magnetic field, the memory jaws heated to above the glass transition temperature can always automatically return to this shape. The memory jaws are then heated, and under conditions above the glass transition temperature, the softened bionic fingers are shaped into a preset retracted shape and then magnetized.

[0079] Before magnetization, the shape of the memory clamp after plastic surgery can be called the second shape of the memory clamp. After magnetization, the magnetic moment arrangement of the permanent magnet particles doped in the bionic finger changes from disorder to order. At this time, even after the external force used to restrict the bionic finger is withdrawn, the bionic finger can continue to be constrained in this state only by the magnetic force exerted on each bionic finger in the magnetic field. In the subsequent application process, it is only necessary to provide an additional magnetic field with the same direction and similar intensity as the strong magnetic field used when the memory clamp is magnetized, so that the softened bionic fingers can be magnetically plasticized above the glass transition temperature, so that they are transformed from the initial shape to the second shape. On the contrary, if the magnetic field used to constrain the shape of the memory clamp in the space where the memory clamp is located is withdrawn at this time, the memory clamp will be autonomously restored to the initial shape from the second shape under the influence of the memory recovery characteristics of the SMP material used in the bionic claw.

[0080] Therefore, based on the above-mentioned magnetic characteristics of the memory jaws provided in this embodiment, in order to achieve the shape control of the memory jaws, the intelligent micro-gripper provided in this embodiment also includes a magnetic field generating device. The magnetic field generating device is used to generate a directional magnetic field that can drive the jaws to bend to a preset shape. In practical applications, the magnetic field generating device can use an electromagnet, and then control the generation and cancellation of the additional magnetic field by adjusting the on and off of the driving current in the electromagnet. In other embodiments, the magnetic field generating device can also directly use a permanent magnet, and drive the permanent magnet to approach or move away from the memory jaw at a specified angle through a linear actuator, so that a corresponding magnetic field is generated around the memory jaw or the magnetic field is "cancelled".

[0081] In the intelligent micro-gripper provided in this embodiment, a controller is used to jointly control the optical signal generator and the magnetic field generating device for adjusting the temperature and magnetic field of the memory clamp, so that the memory clamp can be directly switched between the initial form and the second form to achieve the specified action of clamping the target object and releasing the target object. Specifically, the controller in this embodiment is electrically connected to the optical signal generator and the magnetic field generating device. The controller is used to control the optical signal generator to emit an optical signal to the specified bionic finger to achieve directional heating of the bionic claw, and to control the magnetic field generating device to generate or cancel the magnetic field in the specified area, and then use the magnetic field to drive the bionic claw above the glass transition temperature to change its shape to achieve the specified clamping or release action.

[0082] In actual application, Figure 3 As shown in the figure, when the intelligent micro gripper performs the gripping action, the control logic of the controller is as follows:

[0083] (1) Determine the expected shape of each bionic finger according to the preset gripping posture.

[0084] The shapes of the bionic fingers include upright and bent, and each bionic finger remains upright in the initial state.

[0085] (2) Sending instructions to the optical signal generator to emit optical signals to each bionic finger with the expected curved shape, thereby heating it and converting it from a glass state to a rubber state.

[0086] (3) An opening command is issued to the magnetic field generating device to generate a directional magnetic field of a specified direction and intensity at the position of the memory gripper, so that each bionic finger in the rubber state bends.

[0087] (4) Sending a command to the optical signal generator to stop emitting the optical signal, so that the bent bionic finger cools naturally and returns to the glass state from the rubber state.

[0088] (5) Send a closing command to the magnetic field generating device so that the position of the memory clamp is restored to a non-magnetic field environment; at this time, the memory clamp is in a preset clamping posture.

[0089] Accordingly, if Figure 3 As shown in the figure, when the intelligent micro gripper performs the release action, the control logic of the controller is as follows:

[0090] (1) Determine the expected shape of each bionic finger according to the preset release posture.

[0091] (2) Sending instructions to the optical signal generator to emit optical signals to each bionic finger whose shape changes from bending to upright as expected, heating the bionic finger so that it changes from a glass state to a rubber state and returns to an upright state.

[0092] (3) Sending a command to the optical signal generator to stop emitting the optical signal, so that the bionic finger cools naturally and recovers from the rubber state to the glass state; at this time, the memory gripper completes the release of the clamped object.

[0093] In practical applications, repeatedly executing the above-mentioned joint control strategies of multiple magnetic fields and temperatures can achieve continuous clamping and release of multiple targets to meet actual application needs.

[0094] In the scheme of the present embodiment, by transmitting an optical signal to the bionic finger or base in the memory gripper through an optical fiber, it is possible to heat it to drive the bionic finger to transform between the rubber state and the glass state. In this process, the longer the light signal of each bionic finger is turned on, the more heat each bionic claw absorbs and converts, and the higher its own temperature will be. Therefore, how to control the duration of the transmitted light signal to achieve more accurate temperature control, and then achieve a balance between the regulation effect and the energy consumption and life of the equipment, etc., becomes a technical parameter that needs to be further optimized in the scheme of this embodiment. In response to this problem, this embodiment provides two different ideas to control the emission duration of the light signal.

[0095] Specifically, in the first scheme, this embodiment pre-stores the heating curve and recovery curve of the bionic finger under different infrared powers in the controller. The controller queries the heating curve or the recovery curve according to the current infrared power and heating time to determine the current temperature of the bionic finger, and then identifies the current phase state of the bionic finger. During the heating process, when it is known from the heating curve that the bionic finger exceeds the preset glass transition temperature when heated and is converted from the glass state to the rubber state, the heating process can be terminated in time or the emission power of the light source can be reduced. During the clamping and releasing process of the target object, when it is known from the recovery curve that the bionic finger is lower than the preset glass transition temperature when cooled and is converted from the rubber state to the glass state, it means that the memory clamp has hardened, thereby achieving a firm clamping of the target object, or ending the release action of the target object.

[0096] In the second scheme, each bionic finger of the intelligent micro-gripper of this embodiment is also provided with a micro temperature sensor, and the temperature sensor is electrically connected to the controller through a signal cable. The controller detects the real-time temperature of each bionic finger through the temperature sensor, and then identifies the current phase of the bionic finger. The essence of scheme one is to estimate the temperature of the bionic finger in combination with the heating power working curve, and then make judgments and decisions, while in scheme two, the temperature of the bionic finger is directly measured by the sensor, and the corresponding decision is made. In other schemes, thermal imaging equipment can also be used to perform non-contact temperature detection on the memory gripper or bionic finger.

[0097] The above two methods of obtaining the temperature of the bionic finger can be applied to different scenarios. For example, when the scale of the memory gripper and the bionic finger is relatively large and obviously exceeds the probe of the micro temperature sensor, the second solution can be used. On the contrary, when the scale of the memory gripper and the bionic finger is too small and the implantation of the temperature sensor is not allowed, the first solution can be selected. In the first solution, in order to provide the estimation accuracy of the bionic claw temperature, the heating curve and recovery curve of the bionic finger under different ambient temperatures and heating power conditions can be further obtained through pre-testing, and then the ambient temperature is first obtained in actual application, and then the corresponding heating curve or cooling curve is selected in combination with the ambient temperature, and then the temperature is estimated.

[0098] In the actual product of the intelligent micro-gripper provided in this embodiment, Figure 4 As shown, a multi-degree-of-freedom mechanical arm is also included, and a memory gripper is installed at the end of the mechanical arm, and the mechanical arm is used to drive the memory gripper to move in space. The mechanical arm is electrically connected to a controller, and the controller is used to control the motion trajectory of the mechanical arm.

[0099] Example 2

[0100] On the basis of the solution in Example 1, this embodiment further provides a micro memory gripper including a light-magnetic combined control, which is the memory gripper used in the intelligent micro gripper in Example 1.

[0101] Among them, the micro memory gripper with combined optical and magnetic control includes a base, a plurality of bionic fingers fixedly connected to the surface of the base, and an optical fiber embedded in the base or each bionic finger. The bionic finger is made of a shape memory polymer doped with permanent magnet particles. Each bionic finger is solidified in an upright state and magnetized after being shaped into a preset retracted shape under conditions above the glass transition temperature. The bionic finger has the characteristics of remaining bent under a specified temperature and magnetic field environment and returning to an upright position after the magnetic field is removed; the optical fiber is used to transmit an optical signal that can regulate the temperature of the bionic finger.

[0102] In the product solution of this embodiment, the permanent magnet particles are made of neodymium iron boron powder; the shape memory polymer is configured by epoxy resin and curing agent in a mass ratio of 3:1. In the raw materials for preparing the bionic finger, the doping amount of the permanent magnet particles in the shape memory polymer has an effect on the performance of the memory gripper. When the doping amount of the permanent magnet particles is too low, the magnetic properties of the bionic finger are relatively weak, and it may not be able to achieve the conversion from the initial form to the second form or stable maintenance in the magnetic field after magnetization. When the doping amount of the permanent magnet particles is too high, on the one hand, it may damage the shape memory recovery characteristics of the bionic finger, making it unable to restore the shape autonomously above the glass transition temperature. On the other hand, it will also cause the toughness of the bionic finger to decrease, and it is easy to break or be damaged in a limited number of morphological conversion processes. In this embodiment, the final optimized doping ratio is: the doping amount of the permanent magnet particles in the material is 30-65wt%.

[0103] In the memory gripper, the morphology and spatial distribution of the bionic fingers will also affect the final gripping performance and deformation characteristics of the product. In the more optimized solution determined in this embodiment, the bionic fingers should be distributed in a ring shape on the base, and the four-finger gripper is more versatile and can perform tasks such as gripping and transferring most targets. In this type of memory gripper, the typical structural proportions are: the diameter of each bionic finger is 120μm; the height is 1200μm; the spacing is 800μm.

[0104] The memory clamp provided in the present embodiment can install the optical fiber at each bionic finger, thereby realizing local heating and morphological control of different bionic fingers. Figure 5 As shown in the figure, different bionic fingers in the memory gripper can be shaped differently according to different application scenarios, thereby achieving a more refined manipulation effect. Taking the six-finger gripper as an example, if only two fingers on the opposite side are bent, the "pinch" action can be performed, and when four fingers are driven to bend at the same time, the "grip" action can be achieved.

[0105] The solution provided in this embodiment further provides another method for preparing a memory clamp, which is used to prepare the aforementioned optical-magnetic combined control micro memory clamp, such as Figure 6 As shown, the preparation method comprises the following steps:

[0106] 1. Mold preparation

[0107] A mold with a groove on the surface is prepared by using silicone material, and the groove is consistent with the shape of the base in the memory clamp.

[0108] A plurality of finger-shaped grooves that match the shape and spatial distribution of each bionic finger in the memory gripper are processed in the groove of the mold by a femtosecond laser processing system.

[0109] 2. Curing and molding

[0110] The monomers of the shape memory polymer and the permanent magnet particles are mixed in a preset ratio and vacuum defoamed to obtain material one; the monomers of the shape memory polymer are mixed in a preset ratio and vacuum defoamed to obtain material two.

[0111] The material is injected into the mold to fill the finger grooves, and an optical fiber and / or a temperature sensor are pre-embedded in each finger groove; after scraping off the excess material, the first curing is performed under the specified curing conditions.

[0112] Material 2 is injected into the mold to fill the groove, and then a second curing is performed under specified curing conditions; demolding is performed after the second curing is completed.

[0113] 3. Shaping and magnetization

[0114] The demoulded product is heated to a state higher than the glass transition temperature Tg of the material, and then each bionic finger is bent into a preset shape; and the product is magnetized by a strong magnetic field under forced conditions; thereby obtaining the desired memory gripper.

[0115] Test experiment

[0116] In order to verify the performance of the micro-gripper and memory gripper provided by the present invention, Figure 6 As shown, technicians manufactured corresponding samples and carried out relevant test experiments. The experimental content and data are shown below:

[0117] 1. Sample manufacturing

[0118] 1.1. Template manufacturing:

[0119] The path diagram of the femtosecond laser processing system is drawn according to the spatial distribution state of the bionic fingers in the preset memory gripper. The silicone material is fixed on the glass sheet with double-sided tape, and the path diagram is imported into the femtosecond laser processing system. The designed pattern is processed on the silicone substrate according to the processing parameters of average power 80mW and scanning speed 2mm / s. The number of laser scanning repetitions is adjusted to prepare a micropore array with a high aspect ratio on the silicone material, and then the required silicone template is obtained. The femtosecond laser repeatedly scans the silicone surface in a circular scanning path to increase the depth of micropore processing.

[0120] 1.2. Memory gripper manufacturing:

[0121] Pure SMP is prepared according to the ratio of epoxy resin: curing agent = 3:1, and then NdFeB powder is added to the pure SMP to obtain a mixture material endowed with photothermal response and magnetic response properties. The silicone material used is purchased AB glue in a 1:1 configuration with a thickness of 2mm. The shape memory polymer used is epoxy resin and curing agent in a 3:1 configuration, and the NdFeB powder used has a diameter of 5μm. The evenly stirred mixture is applied to the surface of the silicone template, and vacuumed for 15 minutes to ensure that the mixture completely enters the silicone template structure. Then scrape off the excess mixture on the surface and apply pure SMP again. Finally, after curing and demolding, a four-claw memory clamp structure is obtained.

[0122] Among them, the base uses pure SMP, which is conducive to the transmission of light due to its high transparency; on the other hand, since the infrared absorption rate of pure SMP is relatively low, its surface temperature will be lower than that of the bionic finger doped with NdFeB.

[0123] 1.3. Shaping and magnetization:

[0124] Under near-infrared light irradiation conditions, the bionic fingers (microcolumns) in the memory clamp become softened, and external force is applied to cause the microcolumns to bend inward into a claw shape at the same time. The near-infrared light is removed, the memory clamp is fixed into a temporary shape, and is magnetized in a 1.2T uniform magnetic field to obtain a memory clamp that has both light response and magnetic response.

[0125] In this step, magnetization is used to make the four micro-pillars simultaneously have an inward morphological response under the stimulation of the magnetic field, thereby forming a micro-claw morphology that is conducive to capturing the target. Before magnetization, under the action of the magnetic field, the complete direction of the four micro-pillars is uncertain, so the purpose of manipulation cannot be achieved. After shaping and magnetization, each micro-pillar can maintain a specified shape in the magnetic field. That is, the memory claw can be converted into a two-state state.

[0126] 1.4. Fiber optic integration:

[0127] In this experiment, the end of the optical fiber of the (infrared) fiber laser is bonded to the base of the memory gripper through an adhesive. The fiber laser can generate an optical signal to drive the memory gripper to heat up, and the optical fiber has the characteristics of being able to extend and bend. By utilizing the excellent optical transmission performance of the optical fiber, the memory gripper can be optically driven in a confined space to achieve better control effects and control accuracy on the memory gripper. In this experiment, the fiber laser used is the Changchun New Industry MDL-III-808 model.

[0128] 2. Analysis of factors affecting bending performance:

[0129] In the sample manufacturing process of the memory gripper, this experiment manufactured samples with different NdFeB concentrations and micro-pillar height-to-diameter ratios, and then formulated an experimental plan to test the micro-pillar curvature of the memory gripper with different NdFeB concentrations and micro-pillar height-to-diameter ratios under different driving magnetic field strengths through the control variable method, and then explore the key factors affecting the micro-pillar morphology tuning effect in the memory gripper. During the experiment, the CA100C contact angle measurement system of Innuo Company of China was used to measure the curvature of micro-pillars with different parameters.

[0130] According to the experimental data, the relationship between the doping concentration of NdFeB particles and the bending angle of the microcolumn is as follows: Figure 7 As shown; analysis Figure 7 The data shows that the higher the doping concentration of NdFeB, the greater the bending angle of the microcolumn.

[0131] According to the experimental data, the relationship between the height-to-diameter ratio of the microcolumn and the bending angle of the microcolumn is as follows: Figure 8 As shown; analysis Figure 8 The data show that the larger the aspect ratio of the microcolumn is, the larger the bending angle of the microcolumn is.

[0132] In order to study the relationship between the magnetic induction intensity of the driving magnetic field and the bending angle of the microcolumn, this experiment chooses to adjust the distance between the permanent magnet and the memory claw, and then measure the change of the magnetic field intensity at the memory claw under different permanent magnet distance conditions. Then analyze the change of the bending angle of the microcolumn under different permanent magnet distances (corresponding to different magnetic field intensities). The experimental data obtained are as follows Fig. 9 Analysis Fig. 9 The data shows that: the closer the permanent magnet is to the memory clamp, the higher the magnetic field strength at the memory clamp. When the magnetic field strength is greater, the full angle of the micro-pillar is greater.

[0133] In addition, this experiment can also compare and analyze the changes in the full angle of the corresponding magnetic field for micropillars of different lengths, and the results are also reflected in Fig. 9 From the data in the figure, it can be found that the higher the height of the microcolumn, the greater the bending angle under the same magnetic field.

[0134] 3. Stability Test

[0135] This experiment repeatedly tests the bending and recovery process of memory clamps with different NdFeB concentrations under magnetic field drive to verify the stability of the product. During the repetitive experiment, the technicians found that after the NdFeB doping concentration reaches 70%, the stiffness of the micro-column is too large, which makes the memory clamp easy to break during repeated use, affecting the stability of the product. Therefore, the subsequent experiments should choose products with a NdFeB powder doping content of 50%.

[0136] Furthermore, when the doping content was 50%, the experiment also conducted stability tests under different conditions, resetting the magnetic field and removing the magnetic field, recording the change in the bending angle of the microcolumns, and obtaining the following Fig.10 Data from repeated experiments are shown. Fig.10 It can be found from the data that: even after 10 repeated bending and recovery, the micro-columns in the memory clamp can still maintain a basically consistent curvature, indicating that the memory clamp designed by the present invention has good stability performance.

[0137] 4. Analysis of factors affecting temperature control

[0138] Temperature is the key to achieve morphological regulation and state maintenance of the memory jaws. This experiment further tests and analyzes the relevant factors that affect the temperature regulation effect of the micro-columns in the memory jaws of the present invention. During the experiment, the Fotric 625C-L21 of Shanghai Thermal Imaging Technology Co., Ltd. was used to measure the surface temperature changes of the memory jaws.

[0139] 4.1. Verification of morphological control performance

[0140] This experiment first tested the memory gripper's ability to manipulate a tiny ball in the air under the synergy of optical fiber conduction and magnetic field. The basic principles and actual effects of the experiment are as follows: Fig.11 As shown. Fig.11 Say you can see:

[0141] When the memory clamp is not affected by the external magnetic field and the optical fiber light guide, the microcolumn array is in an upright state and the entire memory clamp is in an initial state. When light is conducted in the optical fiber, the photothermal effect causes the microcolumn array to rapidly heat up to the glass transition temperature. Under the synergistic effect of the external magnetic field, the microcolumn array bends inward to achieve the precise capture of the tiny balls. Next, when the light source and the external magnetic field in the optical fiber are removed at the same time, the microcolumn array still remains bent inward, and the memory clamp maintains its grip on the small balls. When light is output from the optical fiber again, the microcolumn array reaches the glass transition temperature again due to the thermal effect, and then recovers its shape and becomes upright, achieving the rapid release of the tiny balls.

[0142] 4.2 Effect of warm NdFeB doping concentration

[0143] This experiment first studied the temperature change of the memory gripper under the laser signal under the conditions of NdFeB doping concentration of 0%, 10%, 30%, and 50%. The experimental data obtained are as follows Fig.12 The left side of the figure shows the infrared image of the experimental process, and the right side shows the heating curve and cooling curve drawn according to the temperature test results.

[0144] analyze Fig.12From the data, we can find that: when the doping concentration of NdFeB is higher, the heating rate and cooling rate of the memory clamp are faster. This is because the doping of NdFeB affects the absorption rate of the material to the light signal. In order to improve the sensitivity of the memory clamp to the light signal during the regulation process, the doping concentration of NdFeB should be appropriately increased. Of course, the doping concentration of NdFeB cannot be excessively increased, because too high a doping concentration will have a negative impact on the flexibility of the material.

[0145] 4.3 Effect of laser power

[0146] This experiment further studies the relationship between the temperature of the memory clamp at different laser powers. The experimental data obtained are as follows: Fig.13 As shown in the figure, the laser power and the temperature growth of the memory clamp are positively correlated, which means that in order to improve the temperature response rate of the memory clamp, a higher laser power should be used. However, in practical applications, the laser light source should not be too high, because high-power lasers may cause the local temperature of the memory clamp to be too high, which may lead to the burning of the fiber cladding at the interface.

[0147] 4.4 Effect of micro-pillar spacing

[0148] This experiment further tests the heating effect of the memory gripper under different micro-pillar spacings, and the experimental data obtained are as follows Fig.14 As shown in the figure, the micro-column spacing is negatively correlated with the heating effect of the memory clamp. Analysis shows that this may be because the larger the micro-column spacing, the larger the structure that absorbs heat, and the larger the heat dissipation surface between the structures. Based on this data, technicians can reasonably set the structural size of the memory clamp and the number of optical fibers used.

[0149] 5. Testing of multiple application scenarios:

[0150] This experiment further tests the clamping effect of the memory clamp provided by the present invention on clamping different types of objects. Fig.15 The memory gripper is used to grasp a glass ball of the order of 100 micrometers (the ball has a diameter of 500 μm in the figure). This experiment verifies that the memory gripper of the present invention has a stable gripping ability for smooth spherical objects that are difficult to grasp.

[0151] Fig.16 The process of selectively identifying and grasping a target object in a dark environment and releasing it to a designated position using the memory gripper of the present invention is shown. As can be seen from the figure, the laser output through the optical fiber of the present invention can not only achieve temperature regulation, but also has a certain lighting effect, which can facilitate the grasping of the target object in a dark environment.

[0152] Fig.17The process of using the memory gripper of the present invention to grasp a target in a curved pipe is shown. Thanks to the optical fiber transmission strategy of the laser signal adopted by the present invention, the memory gripper of this embodiment can penetrate deep into the pipe to grasp the target. This experiment verifies the target grasping performance of the memory gripper of the present invention in a narrow space.

[0153] Finally, this experiment also used the memory gripper to clamp and non-destructively transform Daphnia. The experimental process is as follows: Fig.18 As shown, the released Daphnia can still remain active, which shows that the memory gripper provided by the present invention can be used to clamp and transfer living targets.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent micro gripper, characterized in that: It includes: A memory gripper, comprising a base, a plurality of bionic fingers fixedly connected to the surface of the base, and an optical fiber embedded in the base or each bionic finger; the bionic fingers are made of a shape memory polymer doped with permanent magnet particles; each of the bionic fingers is solidified in an upright state, and is shaped into a preset retracted shape under conditions above the glass transition temperature and then magnetized; the bionic fingers have the characteristics of remaining bent under a specified temperature and magnetic field environment and restoring to an upright state after the magnetic field is removed; An optical signal generator, comprising a light source and a multi-channel optical switch; The light source is used to generate multiple optical signals and output them through multiple independent output ports; the optical switch is used to control the on and off of each output port; each output port of the light source is connected to the base of the memory gripper or the optical fiber on the bionic finger; A magnetic field generating device, which is used to generate a directional magnetic field capable of driving the clamping jaws to bend to a preset shape; A controller is electrically connected to the optical signal generator and the magnetic field generating device; the controller is used to control the optical signal generator to emit an optical signal to a specified bionic finger to achieve directional heating of the bionic claw, and to control the magnetic field generating device to generate or cancel a magnetic field in a specified area, thereby using the magnetic field to drive the bionic claw above the glass transition temperature to change its shape, so as to achieve a specified clamping or releasing action.

2. The intelligent micro gripper according to claim 1, characterized in that: When the clamping action is performed, the control logic of the controller is as follows: (1) determining the expected shape of each bionic finger according to a preset gripping posture; The bionic fingers have the following shapes: upright and bent. In the initial state, each bionic finger remains upright. (2) issuing a command to the optical signal generator to emit an optical signal to each bionic finger whose expected shape is bending, so that the finger is transformed from a glass state to a rubber state; (3) issuing an opening command to the magnetic field generating device to generate a directional magnetic field of a specified direction and intensity at the position of the memory clamp, so that each bionic finger in the rubber state bends; (4) issuing a command to the optical signal generator to stop emitting the optical signal, so that the bent bionic finger returns from the rubber state to the glass state; (5) Sending a closing command to the magnetic field generating device so that the position of the memory clamp is restored to a non-magnetic field environment; at this time, the memory clamp is in a preset clamping posture.

3. The intelligent micro gripper according to claim 2, characterized in that: When the release action is executed, the control logic of the controller is as follows: (1) determining the expected shape of each bionic finger according to a preset release posture; (2) issuing a command to the optical signal generator to emit an optical signal to each bionic finger whose expected shape changes from bending to upright, so that the finger changes from a glassy state to a rubbery state and then returns to an upright state; (3) Sending a command to the optical signal generator to stop emitting the optical signal, so that the bionic finger returns from the rubber state to the glass state; at this time, the memory gripper completes the release of the clamped object and returns to the initial state.

4. The intelligent micro gripper according to claim 2, characterized in that: The controller pre-stores a heating curve and a recovery curve of the bionic finger at different infrared powers; The controller queries the temperature rise curve or the recovery curve according to the current infrared power and the heating time, and further identifies the current phase state of the bionic finger.

5. The intelligent micro gripper according to claim 1, characterized in that: Each bionic finger is also provided with a miniature temperature sensor, which is electrically connected to the controller via a signal cable; The controller detects the real-time temperature of each bionic finger through a temperature sensor, and then identifies the current phase state of the bionic finger.

6. The intelligent micro gripper according to claim 1, characterized in that: It also includes a multi-degree-of-freedom mechanical arm, the memory gripper is installed at the end of the mechanical arm, and the mechanical arm is used to drive the memory gripper to move in space; The robotic arm is electrically connected to the controller, and the controller is used to control the motion trajectory of the robotic arm.

7. A micro memory gripper with optical and magnetic combined control, characterized in that: It includes a base, a plurality of bionic fingers fixedly connected to the surface of the base, and an optical fiber embedded in the base or each bionic finger; the bionic fingers are made of a shape memory polymer doped with permanent magnet particles; each bionic finger is solidified in an upright state, and is shaped into a preset retracted shape under conditions above the glass transition temperature and then magnetized; the bionic fingers have the characteristics of remaining bent under a specified temperature and magnetic field environment and restoring to an upright state after the magnetic field is removed; The optical fiber is used to transmit an optical signal capable of regulating the temperature of the bionic finger.

8. The optical-magnetic combined controlled micro memory gripper according to claim 7, characterized in that: The permanent magnet particles are made of neodymium iron boron powder; the shape memory polymer is made of epoxy resin and curing agent in a mass ratio of 3:1; The doping amount of the permanent magnet particles in the material for preparing the bionic finger is 30-65wt%.

9. The optical-magnetic combined controlled micro memory gripper according to claim 7, characterized in that: The bionic fingers are distributed in a ring shape on the base, and each bionic finger has a diameter of 120 μm, a height of 1200 μm, and a spacing of 800 μm.

10. A method for preparing a memory clamp, characterized in that: It is used to prepare the optical-magnetic combined control micro memory clamp as claimed in any one of claims 7 to 9, and the preparation method comprises the following steps:

1. Mold preparation A mold with a groove on the surface is prepared by using a silicone material, wherein the groove matches the shape of the base in the memory clamp; A plurality of finger-shaped grooves that match the shapes and spatial distributions of the bionic fingers in the memory gripper are processed in the groove of the mold by a femtosecond laser processing system; 2. Curing and molding The monomers of the shape memory polymer and the permanent magnet particles are mixed in a preset ratio and vacuum defoamed to obtain material one; the monomers of the shape memory polymer are mixed in a preset ratio and vacuum defoamed to obtain material two; Inject the material into the mold to fill the finger grooves, and embed optical fibers and / or temperature sensors in each finger groove; scrape off excess material and perform the first curing under specified curing conditions; Inject material 2 into the mold to fill the groove, and then perform a second curing under specified curing conditions; Demoulding after the second curing is completed; 3. Shaping and magnetization The demoulded product is heated to a state higher than the glass transition temperature Tg of the material, and then each bionic finger is bent into a preset shape; and the product is magnetized by a strong magnetic field under forced conditions; thereby obtaining the desired memory gripper.

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