Multi-scale self-adaptive electrothermal magnetic driving type clamping robot and memory clamping jaw

Abstract

The invention belongs to the field of flexible micro-robots, and particularly relates to a multi-scale self-adaptive electrothermal magnetic driving type clamping robot and a memory clamping jaw. The clamping robot comprises a memory clamping jaw, a movement mechanism, an adjustable power supply and a controller. The memory clamping jaw comprises a base and a plurality of bent clamping arms. And a heating unit is pre-embedded in a base body of the clamping arm. The substrate is prepared from a shape memory polymer filled with a ferromagnetic material or permanent magnet particles. And in a natural state, each clamping arm is in a folded state. The movement mechanism is connected with a base of the memory clamping jaw. The adjustable power supply is electrically connected with the heating units of the clamping arms. The controller drives the memory clamping jaw to move through the movement mechanism and can also accurately regulate and control the heating duration and the heating power of the clamping arm in the maximum expansion state without depending on a magnetic field, so that target objects of different sizes are efficiently grabbed. The problems that an existing clamping robot is large in action regulation and control difficulty and prone to being interfered by a magnetic field are solved.

Description

Technical Field

[0001] The present invention belongs to the field of flexible micro-robots, and in particular relates to a multi-scale adaptive electrothermal magnetic driven clamping robot and a memory clamping claw used therein. Background Art

[0002] The gripping robot based on shape memory polymer (SMP) is a cutting-edge micro-flexible robot. Different from the traditional robot based on electromechanical devices, the memory recovery characteristics of SMP in this type of robot enable the robot body and its components to be restored to their original shape under external stimulation (such as heat, electricity, magnetism, light, etc.), and thus realize motion control; therefore, it 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 and magnetic drive. Among them, electrothermal drive technology controls the movement of robot parts by electrically heating them. The implementation methods include: (1) using dielectric elastomer (DEA) as the matrix; (2) doping carbon fillers (graphene, carbon black, carbon fiber, etc.) in the shape memory polymer matrix; (3) doping metal fillers (gold, silver nanoparticles, etc.) in the shape memory polymer matrix. Photothermal drive technology includes laser drive, fiber drive, infrared light drive and ultraviolet light drive. (3) Magnetic drive technology makes the robot parts magnetically conductive, and then controls their execution through dynamic magnetic fields.

[0004] In actual application, the above three driving technologies all have certain defects, such as:

[0005] For electrothermal drive technology: Memory grippers made of dielectric elastomers (DEA) require very high voltages (usually thousands of volts) to operate, which can easily cause dielectric breakdown, pose safety risks, and lack biosafety. Carbon fillers often have problems such as slow thermal conductivity and uneven heating, which affect the response time (generally tens to hundreds of seconds), and lack grasping strategies for fragile objects. Metal fillers are expensive and easily oxidized in the air.

[0006] Regarding photothermal drive technology: The photothermal memory gripper has a longer response time due to its soft material, but also has low rigidity. It often relies on the adhesion force generated by the normal friction force, resulting in insufficient clamping force. And this driving method can only achieve the "clamping" action, which is difficult to handle objects with large loads. In addition, the driving effect of the photothermal memory gripper has limitations when applied in complex space environments, such as in certain occlusion states, and then achieve light excitation.

[0007] Regarding magnetothermal drive technology: Due to the low magnetic susceptibility of ferrite materials, the load capacity of magnetically driven memory grippers is relatively low (tens to hundreds of times their own weight); at the same time, magnetically driven memory grippers need to follow the magnetic field throughout their operation, and need to work in a non-magnetic field environment to avoid interference of the ambient magnetic field with the driving magnetic field. Therefore, magnetothermal-driven gripping robots are usually not used to grasp ferromagnetic objects, and their flexibility is limited. Summary of the invention

[0008] In order to solve the problem that the motion control of existing SMP-based gripping robots is difficult and easily restricted by factors such as spatial obstacles and environmental magnetic fields, the present invention provides a multi-scale adaptive electrothermal magnetic driven gripping robot and a memory gripper used therein.

[0009] The technical solution provided by the present invention is:

[0010] A multi-scale adaptive electrothermal magnetic driven gripping robot is used to grasp and transfer targets of different shapes and sizes between a picking space and a storage space. The storage space used in the solution is provided with a fixed magnetic field for driving the gripping robot to release the target and restore the shape. The multi-scale adaptive electrothermal magnetic driven gripping robot provided by the present invention includes: a memory gripper, a motion mechanism, an adjustable power supply, and a controller.

[0011] The memory clamp includes a base and a plurality of curved clamp arms arranged in a ring shape below the base. The free ends of the clamp arms away from the base are close to each other; the clamp arms include a base and a heating unit embedded in the base. The base is made of a shape memory polymer filled with ferromagnetic material or permanent magnet particles. In a natural state, each clamp arm in the memory clamp is in a retracted state.

[0012] The motion mechanism is movably connected to the base of the memory clamp. The adjustable power supply is electrically connected to the heating unit in each clamp arm and is used to adjust the switch state and heating power of the heating unit.

[0013] The controller is electrically connected to the adjustable power supply and the motion mechanism; the controller includes a motion control unit and a thermal control unit. The motion control unit is used to issue instructions to the motion mechanism, thereby controlling the motion mechanism to drive the memory gripper to move freely in the specified space. The thermal control unit is used to issue instructions to the adjustable power supply, thereby achieving: (1) when picking up objects, a preset heating parameter mapping table is queried according to the ambient temperature of the picking space and the scale of the target object, and then the heating unit is controlled to operate according to the specified heating power and heating time according to the query result, so that the temperature of each clamp arm is just lower than the glass transition temperature Tg when it recovers from the maximum expansion state to the expansion state consistent with the scale of the target object, reaches the hardening state and grasps the target object; (2) when placing objects, the electric heating unit is first controlled to operate according to the maximum heating power so that the temperature of each clamp arm is higher than the glass transition temperature to complete the release of the target object. At this time, under the action of the fixed magnetic field, the free ends of each clamp arm after softening recover to the maximum expansion state; then the electric heating unit is controlled to stop working so that the clamp arm remains hardened in the maximum expansion state.

[0014] As a further improvement of the present invention, a temperature sensor is also installed on the base of the memory clamp, and the temperature sensor is electrically connected to the controller and is used to detect the ambient temperature around the memory clamp.

[0015] As a further improvement of the present invention, the clamping arm adopts an arc-shaped thin sheet or a bent multi-segment thin sheet.

[0016] As a further improvement of the present invention, the number of clamping arms in the memory clamp is not less than 2, and the structure is bionic hand grasping action.

[0017] As a further improvement of the present invention, the base material of the clamp arm is composed of epoxy resin, epoxy resin curing agent and Fe 3 O 4 The particles are mixed in a mass ratio of 3:1:4.

[0018] As a further improvement of the present invention, the heating unit includes a resistance wire and an electrode; the resistance wire is located in the substrate and has a mesh structure; the electrode is electrically connected to the thermal control unit in the controller.

[0019] As a further improvement of the present invention, a rough texture is provided on the inner side of the free end of each clamping arm in the memory clamping jaw, and the rough texture is used to increase the friction between the memory clamping jaw and the grasped target object.

[0020] As a further improvement of the present invention, the motion mechanism adopts a multi-axis mechanical arm or a truss robot.

[0021] As a further improvement of the present invention, the ambient temperature of the object-taking space and the object-storing space is lower than the glass transition temperature Tg of the shape memory polymer used in the clamping arm.

[0022] As a further improvement of the present invention, a permanent magnet for generating a required fixed magnetic field is arranged in the storage space.

[0023] As a further improvement of the present invention, the heating parameter mapping table is used to characterize the values ​​of heating power W and heating time t that meet the minimum power consumption constraint when the memory gripper is restored from the maximum expansion state to the state of the specified opening distance D under each ambient temperature T. The opening distance corresponds to the size of the target object when the clamping arm of the memory gripper can maintain a stable clamping effect in different contraction states.

[0024] As a further improvement of the present invention, the method for constructing the heating parameter mapping table is:

[0025] S1: The working temperature range of the multi-scale adaptive electrothermal magnetic driven gripping robot is divided into a plurality of different temperature intervals, and the heating power of the heating unit is divided into a plurality of gears.

[0026] S2: Test the time required to heat the memory jaws from the hardened maximum expansion state to the softened fully retracted state at the lowest temperature and the highest gear state, and record it as the maximum heating time.

[0027] S3: Set the ambient temperature of the test environment to the specified minimum temperature range, and then perform the following test tasks:

[0028] S31: The heating power is set to the lowest gear, the heating time is increased at equal intervals, and the opening distance of the memory jaws when the memory jaws are finally restored to hardening after being heated for different lengths of time is recorded.

[0029] S32: Increase the gear of the heating power, repeat step S31, test and record the opening distance of the memory jaws when the memory jaws are finally restored to hardening under different gears and different heating time conditions.

[0030] S33: setting the ambient temperature of the test environment to a higher temperature range, repeating steps S31-S32, testing and recording the opening distance of the memory jaws when the memory jaws are finally restored to hardening under different ambient temperatures, different gears and different heating times.

[0031] S4: Based on the data recorded in the test task, generate a feature vector consisting of a series of associated values ​​of ambient temperature T, heating power W, heating time t and opening distance D: denoted as (T, P, t, D); and obtain the original vector set A.

[0032] S5: Filter out multiple vectors with the same T value and D value in the original vector set to form a redundant vector set, and then obtain multiple redundant vector sets.

[0033] S6: Calculate the power consumption W of each feature vector in each redundant vector set, and delete the feature vector with the smallest power consumption:

[0034] W = P·t.

[0035] S7: Delete the feature vectors in the original vector set that are the same as the redundant vector sets, and then construct a heating parameter mapping table for characterizing the P and t values ​​corresponding to each set of T and D values ​​according to the remaining feature vectors of the original vector set.

[0036] The present invention also includes a memory clamp, which includes a base and a plurality of curved clamp arms arranged in an annular manner below the base. The free ends of the clamp arms away from the base are close to each other and are in a retracted state. The clamp arms include a base and a heating unit embedded in the base; the base is made of a shape memory polymer filled with ferromagnetic material or permanent magnet particles.

[0037] As a further improvement of the present invention, the preparation method of the memory clamp is as follows:

[0038] (1) A femtosecond laser processing system is used to process a number of grooves on the silicone template that match the shape of the clamping arms in the memory clamp. The processing parameters are:

[0039] The laser wavelength is 800 nm, the pulse width is 104 fs, and the frequency is 1 kHz; the scanning strategy is set to linear scanning, the scanning speed is 20 mm / s, and the scanning spacing is 60 μm.

[0040] (2) The epoxy resin monomer and epoxy resin curing agent used to synthesize the SMP material are mixed in a ratio of 3:1, and no less than 20%wt of Fe 3 O 4 The particles are mixed evenly and vacuum defoamed to obtain the desired matrix material.

[0041] (3) filling a portion of the matrix material into the groove of the silicone template in a vacuum environment, and then placing the resistance wire and the electrode as the heating unit into the groove after assembly, and continuing to fill the matrix material until the groove is filled, and scraping off the excess material;

[0042] (4) curing the silicone mold filled with the matrix material and the heating unit at a temperature not lower than 80° C. for 2 h, and obtaining the desired clamp arm after demolding;

[0043] (5) Each clamping arm is fixedly connected to a pre-prepared base according to a specified arrangement to obtain the required memory clamping jaws.

[0044] The technical solution provided by the present invention has the following beneficial effects:

[0045] The present invention provides a multi-scale adaptive electrothermal magnetic driven gripping robot. This solution embeds a resistance wire inside the clamping arm of the memory gripper to achieve internal heating, which not only achieves uniform heating, but also makes the memory gripper show a more excellent heating speed, and increases the response time to 0.9 seconds. At the same time, based on this new type of memory gripper, the present invention innovates the control method of the gripping robot. By accurately controlling the heating power and heating time of the memory gripper, the recovery process of the memory gripper can be controlled, thereby achieving the grasping of targets of different sizes without relying on an external magnetic field.

[0046] The gripping robot of the present invention only needs to rely on the magnetic field when the memory gripper releases the opening action of the object, and no longer relies on the magnetic field during the closing process of grasping the object. Therefore, it can be used for capturing and transferring magnetic objects and has high flexibility.

[0047] The memory clamp of the present invention is provided by Fe 3 O 4 The doping of nanoparticles or other ferromagnetic materials enables the memory gripper to respond to magnetic fields. 3 O 4 The addition of particles increases the Young's modulus of the memory gripper, which complements the structural design and works together to improve the load-bearing capacity of the gripping robot.

[0048] The clamping robot provided by the present invention adopts arc-shaped clamping arms to form memory claws. When grasping, the "arms" are closed to achieve "wrapping" of the object. Compared with the previous technology that mostly relies on adhesion and friction for fixing, the structural optimization of the present invention is expected to significantly improve the load-bearing capacity of the clamp.

[0049] The present invention processes a mold by femtosecond laser and then mass-produces the clamping arms in the memory clamping jaws by casting, thereby improving the consistency of product quality and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the structure of the memory gripper used in the gripping robot provided in Example 1 of the present invention.

[0051] Figure 2 This is a flow chart of the preparation of the memory clamp in Example 1 of the present invention.

[0052] Figure 3 This is a schematic diagram of the control part of the clamping robot in Example 1 of the present invention.

[0053] Figure 4 To verify the experiment, the storage modulus and loss modulus change curves of pure SMP and P50-50 samples in the range of 20 to 120°C.

[0054] Figure 5 To verify the experiment, the spatial distribution of magnetic induction intensity in the circular magnetic field simulation and the measured magnetic field is compared.

[0055] Figure 6 To verify the influence curve of different resistance wire diameters on the heating performance of the clamp arm in the experiment.

[0056] Figure 7 Schematic diagram of the state change process corresponding to the three response times in the verification experiment

[0057] Figure 8 To verify the experiment, different Fe 3 O 4 Comparison of the effects of content, current, arm thickness and arm width on the response speed of the memory gripper.

[0058] Fig. 9 To verify the experiment, different Fe 3 O 4 Comparison of the effects of content, current size and arm thickness on the SMP deformation distance.

[0059] Fig.10 Schematic diagram of the principle for verifying the inertial distance defined in the experiment.

[0060] Fig.11 To verify the experiment, different Fe 3 O 4 A comparison chart of the effects of content, current size and arm thickness on the inertia distance of the memory gripper.

[0061] Fig.12 To verify the experimental image of using memory grippers to non-destructively grasp and release soft tofu.

[0062] Fig.13 To verify the experiment, different Fe 3 O 4 A comparison chart of the effects of content, number of arms, arm thickness, and arm width on the load-bearing capacity of memory grippers.

[0063] Fig.14 Experimental image of the memory gripper grabbing the N52 magnet in the verification experiment. DETAILED DESCRIPTION

[0064] 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.

[0065] Example 1

[0066] The present embodiment provides a multi-scale adaptive electrothermal magnetic driven gripper robot, which is used to grasp and transfer targets of different shapes and sizes between a picking space and a storage space. The core components of this type of multi-scale adaptive electrothermal magnetic driven gripper robot include a memory gripper and a motion mechanism. The memory gripper is used to grasp targets of different sizes to be transferred. The motion mechanism is movably connected to the base of the memory gripper. The motion mechanism is used to drive the memory gripper to move freely in a specified space, thereby realizing the transfer of the target object. In the present embodiment, the motion mechanism can adopt a multi-axis robotic arm or a truss robot, etc.

[0067] Unlike traditional mechanical claws that require motors and other equipment for motion control, the memory claw in this embodiment is made of shape memory polymers, and the opening and closing of the memory claw is regulated by electric heating and magnetic fields. Therefore, the multi-scale adaptive electrothermal magnetic driven gripper robot in this embodiment can not only be used to squeeze and grasp objects of different sizes, but also can achieve extreme miniaturization far beyond the robot arm, and then be applied to special fields such as aerospace, biomedicine, 4D printing, and flexible microelectronics.

[0068] like Figure 1 As shown, the memory gripper used in the gripping robot provided in this embodiment includes a base and a plurality of curved gripper arms arranged in a ring below the base. The free ends of the gripper arms away from the base are close to each other. In actual products, the gripper arms can be used as follows Figure 1 The multiple arc-shaped thin sheets shown may also be bent multi-section thin sheets, such as a V-shaped or L-shaped two-section clamp arm, or a three-section clamp arm with both sides bent inward. In order to achieve stable clamping of the target object, the number of clamp arms in each memory clamp is not less than 2. For example, when the number of clamp arms is two, the two clamp arms can be set in a mirror image, and then the distance between the ends of the two clamp arms can be adjusted to "clamp" the target object. When the number of clamp arms is more than three, the clamp arms are distributed in a ring shape to form a structure that presents a bionic hand grasping action to "grasp" the target object. In particular, the inner side of the free end of each clamp arm in the memory clamp is provided with a rough texture, and the rough texture is used to increase the friction between the memory clamp and the grasped target object to prevent the target object from falling off during the clamping process.

[0069] In the memory clamp of the present embodiment, the clamp arm includes a matrix and a heating unit embedded in the matrix. The matrix is ​​made of a shape memory polymer filled with ferromagnetic material or permanent magnet particles. In a natural state, each clamp arm in the memory clamp is in a retracted state. Among them, the ferromagnetic materials that can be used to prepare the clamp arm include iron, cobalt, nickel and their alloys, as well as certain rare earth elements and their alloys. The permanent magnet particles are made of hard magnetic materials that can maintain constant magnetism after magnetization, such as aluminum-nickel-cobalt permanent magnet alloys, iron-chromium-cobalt permanent magnet alloys, permanent magnet ferrites, rare earth permanent magnet materials or composite permanent magnet materials.

[0070] In the clamp arm of the present embodiment, the heating unit includes a resistance wire and an electrode; the resistance wire is located in the matrix and has a mesh structure. The heating unit can heat the clamp arm as a whole, thereby quickly changing the matrix temperature of the clamp arm. Since the matrix of the clamp arm is made of a shape memory polymer, it will exhibit different states at different temperatures. For example, under conditions above the glass transition temperature Tg, the clamp arm is in a soft rubber state. At this time, the clamp arm can be deformed freely under the action of external force, or it can be restored to its original shape autonomously without the action of external force. Under conditions below the glass transition temperature Tg, the clamp arm is in a hard glass state. At this time, the shape of the clamp arm remains stable and is difficult to deform under the action of external force.

[0071] It should be noted that the morphology and doping amount of the ferromagnetic material or permanent magnet particles in the matrix material will affect the response characteristics of the clamp arm to the magnetic field in the rubber state (such as sensitivity and deformation), and will also act as aggregate to change the structural strength of the clamp arm in the glass state. Therefore, the morphology and doping amount of different types of ferromagnetic materials or permanent magnet particles in the matrix material of the clamp arm can be adaptively adjusted according to the material properties and the requirements for product performance.

[0072] like Figure 2 As shown, the preparation method of the memory clamp in this embodiment is as follows:

[0073] (1) The epoxy resin monomer and epoxy resin curing agent used to synthesize the SMP material are mixed in a ratio of 3:1, and no less than 20%wt of Fe 3 O 4 The particles are mixed evenly and vacuum defoamed to obtain the desired matrix material.

[0074] In a typical solution of this embodiment, the two monomer components of SMP are selected from E52 epoxy resin and D230 curing agent. 3 O 4 The particle size of the microparticles is 1 μm. The base material of the clamp arm can be made of epoxy resin, epoxy resin curing agent and Fe 3 O 4The particles are mixed in a mass ratio of 3:1:4. After the proportioning is completed, the shape memory polymer containing ferromagnetic material (referred to as F-SMP) needs to be placed in a vacuum drying oven for 5-10 minutes to remove the tiny bubbles generated during the mixing and stirring process.

[0075] (2) A femtosecond laser processing system is used to process a number of grooves on the silicone template that match the shape of the clamping arms in the memory clamp. The processing parameters are:

[0076] The laser wavelength is 800 nm, the pulse width is 104 fs, and the frequency is 1 kHz; the scanning strategy is set to linear scanning, the scanning speed is 20 mm / s, and the scanning spacing is 60 μm.

[0077] (3) Fill part of the matrix material into the groove of the silicone template in a vacuum environment, then place the resistance wire and electrode as the heating unit into the groove after assembly, and continue to fill the matrix material until the groove is filled, and scrape off the excess material. The resistance wire in this embodiment is nickel-chromium wire, and the wire diameter of the resistance wire can be selected according to the power requirement, and the typical value is 40μm. In this step, the purpose of vacuuming is to allow the F-SMP to fully enter the gap of the silicone template to ensure that the final manufactured clamp arm remains uniform and prevent cavities and defects.

[0078] (4) The silicone mold filled with the matrix material and the heating unit is cured at a temperature not lower than 80° C. for 2 h, and the desired clamp arm is obtained after demolding.

[0079] (5) Each clamping arm is fixedly connected to a pre-prepared base according to a specified arrangement to obtain the required memory clamping jaws.

[0080] In this embodiment, the clamp arm can be bonded to the base, or a slot can be opened on the base, and a plug connector with a corresponding structure is provided at the non-free end of the clamp arm, and then the clamp arm and the base are plugged and fixed.

[0081] Based on the above structure and material properties, the memory gripper provided in this embodiment realizes the control method of grasping and transferring objects of different shapes and sizes as follows:

[0082] When it is necessary to grasp the target object, firstly, each clamp arm is transformed from the glass state to the rubber state by heating. Secondly, the magnetic field is used to apply attraction to the memory clamp to cause each clamp arm to deform, thereby adjusting the distance between the free ends of each clamp arm. When the distance between the free ends of the clamp arm changes, the opening distance D of the memory clamp arm will also change. Finally, after placing the target object under the softened clamp arm, the heating is stopped, so that the clamp arm is transformed from the rubber state to the glass state, thereby maintaining a stable grasping effect.

[0083] When the target object needs to be released, the clamp arms are heated again, so that each clamp arm is transformed from the glass state to the rubber state. At this time, the softened clamp arms lose their clamping effect on the target object, and the target object will fall off naturally under the action of gravity. Of course, for lightweight targets that cannot fall off on their own, the magnetic field can be used to drive the opening distance of the clamp jaws to expand (i.e., memory clamp jaws open) to actively release the target object.

[0084] Combined with the above description of the control logic of the memory gripper, it can be seen that the memory gripper usually needs to use a specific magnetic field to adjust its own opening distance on demand when performing grasping and releasing tasks, which will limit the application of the gripping robot in complex magnetic field environments. In this regard, the multi-scale adaptive electrothermal magnetic driven gripping robot provided in this embodiment further adds an adjustable power supply and controller. The operating logic of the gripping robot is readjusted in conjunction with the adjustable power supply and controller, so that the memory gripper can adjust its own opening distance without relying on the magnetic field; and can be used to grasp and transfer targets of different scales.

[0085] It should be emphasized that: although the improved scheme realizes that the grasping of the target object can be adjusted without relying on the magnetic field, the release of the target object still requires the assistance of the magnetic field. Therefore, a fixed magnetic field should be provided in the storage space used in the scheme of this embodiment to drive the holding robot to release the target object and restore the shape. Taking the arc-shaped clamp arm shown in the figure as an example, the role of the fixed magnetic field is to generate an attractive force on one side of the free end of the clamp arm in the memory clamp, straighten this end of the arc-shaped clamp arm, and achieve the effect of controlling the "opening" of the memory clamp. In practical applications, an annular permanent magnet can be placed in the storage space to generate the required fixed magnetic field.

[0086] Specifically, in the solution of this embodiment, the adjustable power supply is electrically connected to the heating unit in each clamp arm; the adjustable circuit has multiple outputs that match the number of clamp arms in the memory clamp, and each output port is connected to an electrode in one of the heating power supplies. Each output of the adjustable circuit can synchronously adjust the switch state and heating power of the heating unit in each clamp arm.

[0087] The controller is electrically connected to the adjustable power supply and the motion mechanism; Figure 3 As shown, the controller includes a motion control unit and a thermal control unit. The motion control unit is used to issue instructions to the motion mechanism, thereby controlling the motion mechanism to drive the memory gripper to move freely in a specified space. For example, the motion mechanism can move the memory gripper above the target object to accurately grasp the target object; after grasping the target object, the gripper and the target object are transferred from the object picking space to the object placing space. And after releasing the target object, the memory gripper is retracted.

[0088] The thermal control unit is used to issue instructions to the adjustable power supply, thereby achieving: (1) When picking up an object, a preset heating parameter mapping table is queried according to the ambient temperature of the picking space and the size of the target object, and then the heating unit is controlled to operate according to the specified heating power and heating time according to the query result, so that the temperature of each clamp arm is just lower than the glass transition temperature Tg when it recovers from the maximum expansion state to the expansion state that matches the size of the target object, reaches the hardening state and grasps the target object. (2) When placing an object, the electric heating unit is first controlled to operate at the maximum heating power so that the temperature of each clamp arm is higher than the glass transition temperature to complete the release of the target object. At this time, under the action of the fixed magnetic field, the free ends of each clamp arm after softening return to the maximum expansion state; then the electric heating unit is controlled to stop working so that the clamp arm remains hardened in the maximum expansion state.

[0089] In combination with the above content, it can be known that the working logic of the gripping robot of this embodiment is: before grasping the target object and after releasing the target object, the opening degree of the memory gripper is always restored to the same state. When grasping an object, the memory recovery characteristics of the base material of the gripper arm are utilized so that each gripper arm of the memory gripper gradually recovers from the maximum expansion state to the original closed state under a temperature condition higher than the glass transition temperature. On this basis, considering that the process of shape recovery of the memory gripper is a gradual process, therefore, this embodiment can achieve precise interruption of the shape recovery process of the memory gripper by precisely regulating the heating power and heating time of the gripper arm, so that the memory gripper can always be restored to an expansion state that matches the target object to be grasped, thereby achieving the technical effect of grasping targets of different shapes and sizes. A permanent magnet for generating the required fixed magnetic field is provided in the storage space.

[0090] When the multi-scale adaptive electrothermal magnetic driven gripper robot provided in this embodiment works in the picking space and the storage space, in order to maintain the desired shape, the clamp arm needs to gradually release heat to the outside world after stopping heating in the rubber state, and then return to the hard glass state. Therefore, when the gripper robot is used, the ambient temperature of the picking space and the storage space is lower than the glass transition temperature Tg of the shape memory polymer used in the clamp arm. And in order to shorten the conversion time of the memory gripper from the rubber state to the glass state, the ambient temperature of the picking space and the storage space should be as low as possible. For example, in actual applications, temperature control equipment can be installed in the two spaces to maintain the ambient temperature of the picking space and the storage space below 10°C.

[0091] According to the foregoing content, the gripping robot of this embodiment accurately grasps the timing of interrupting the memory recovery process of the gripping arm by adjusting the heating power and heating time of the gripping arm, thereby accurately grasping objects of different sizes. However, the opening distance D of the memory gripper after deformation recovery is not only related to the heating power P and heating time t of the heating unit, but also to the ambient temperature T. On this basis, in order to enable the controller to achieve precise control, this embodiment presets a "heating parameter mapping table" constructed based on a large amount of real experimental data in the controller. The heating parameter mapping table is used to characterize the values ​​of heating power and heating time that meet the minimum power consumption constraint when the memory gripper is restored from the maximum expansion state to the specified opening distance state under each ambient temperature T.

[0092] It should be noted that the heating parameter mapping table of this embodiment is a strict single shot, and there is a one-to-one correspondence between D, T and P, t. Under certain ambient temperature conditions, in order to achieve a specific opening distance, there may be multiple sets of different heating power and heating time values ​​to choose from. The heating parameter mapping table constructed in this embodiment selects the one with the lowest comprehensive power consumption. In other embodiments, technicians can also select the one with the shortest heating time to improve the response characteristics of the memory gripper.

[0093] In this embodiment, when the gripping robot needs to grasp a target of a certain size, the controller needs to query the heating parameter mapping table based on the known ambient temperature and the required opening distance to determine the required heating power and heating time. Then the output of the dynamic power supply can be controlled. In actual applications, when the object-picking space and the storage space are constant temperature spaces, the corresponding ambient temperature values ​​can be preset. When the temperature environment of the object-picking space and the storage space is not constant, a temperature sensor can be installed on the base of the memory gripper, and the temperature sensor collects the surrounding ambient temperature in real time and sends it to the controller.

[0094] In the solution of this embodiment, the heating parameter mapping table is the key information for grasping objects of different sizes, and its construction method is as follows:

[0095] S1: The working temperature range of the multi-scale adaptive electrothermal magnetic driven gripping robot is divided into a plurality of different temperature intervals, and the heating power of the heating unit is divided into a plurality of gears.

[0096] S2: Test the time required to heat the memory jaws from the hardened maximum expansion state to the softened fully closed state at the lowest temperature and the highest gear state, and record it as the maximum heating time t max .

[0097] S3: Set the ambient temperature of the test environment to the specified minimum temperature range, and then perform the following test tasks:

[0098] S31: The heating power is set to the lowest gear, the heating time is increased at equal intervals, and the opening distance of the memory jaws when the memory jaws are finally restored to hardening after being heated for different lengths of time is recorded.

[0099] S32: Increase the gear of the heating power, repeat step S31, test and record the opening distance of the memory jaws when the memory jaws are finally restored to hardening under different gears and different heating time conditions.

[0100] S33: setting the ambient temperature of the test environment to a higher temperature range, repeating steps S31-S32, testing and recording the opening distance of the memory jaws when the memory jaws are finally restored to hardening under different ambient temperatures, different gears and different heating times.

[0101] S4: Based on the data recorded in the test task, generate a feature vector consisting of a series of associated values ​​of ambient temperature T, heating power W, heating time t and opening distance D: denoted as (T, P, t, D); and obtain the original vector set A.

[0102] S5: Filter out multiple vectors with the same T value and D value in the original vector set to form a redundant vector set, and then obtain multiple redundant vector sets.

[0103] S6: Calculate the power consumption W of each feature vector in each redundant vector set, and delete the feature vector with the smallest power consumption:

[0104] W = P·t.

[0105] S7: Delete the feature vectors in the original vector set that are the same as those in each redundant vector set, and then construct a heating parameter mapping table for characterizing the values ​​of P and t corresponding to each group of T and D values ​​based on the remaining feature vectors of the original vector set, that is: (T, D)→(P, t).

[0106] Verification experiment

[0107] In order to verify the performance of the multi-scale adaptive electrothermal magnetic driven gripping robot provided by the present invention, technicians formulated an experimental plan, manufactured corresponding memory gripper samples, and carried out performance tests using different types of samples.

[0108] 1. Sample manufacturing

[0109] This experiment uses E52 epoxy resin and D230 curing agent purchased from Kunshan Jiulimei Electronic Materials Co., Ltd. to prepare shape memory polymer. The ratio of epoxy resin to curing agent affects the shape memory function of SMP. Based on a large number of experimental explorations, this experiment determined that the ratio of epoxy resin to epoxy resin curing agent used was 3:1, and then different contents of Fe were added to the SMP material. 3 O 4 The microparticles (1 μm in diameter, purchased from Hebei Chengyue Metal Materials Co., Ltd.) were stirred for 10 minutes and the F-SMP matrix was prepared after being fully mixed.

[0110] In this experiment, a femtosecond laser processing system was selected to process the manufacturing mold of the clamp arm in the memory gripper. The femtosecond laser processing system uses the Chameleon Vision-S seed laser and Legend Elite F HE-1K titanium sapphire chirped pulse amplification system from Coherent, USA. During the processing, it is necessary to set laser parameters, such as laser power, scanning speed, laser wavelength, pulse width and frequency. The femtosecond laser vertical cross scanning processing method was selected to etch silicone templates of different thicknesses to prepare several arc grooves. In this experiment, arc grooves of clamp arms of different sizes were prepared to study the influence of the wall thickness and arm width of the clamp arm on the clamping performance of the memory gripper.

[0111] In this experiment, multiple clamp arms are manufactured in batches through the processed mold, and then the required memory clamps are assembled. When manufacturing the clamp arms, first pour a small amount of the mixed F-SMP matrix into the groove of the mold, then put the resistance wire into the processed groove, continue to pour the F-SMP matrix, scrape the surface clean, draw a vacuum for ten minutes, make the F-SMP matrix fit tightly with the groove, and heat at 80℃ for 2h. After curing, demolding is carried out to obtain multiple arc-shaped strip-shaped clamp arms. The top of the clamp arm is tightly bonded to the pre-prepared base, and the resistance wire electrode segment is led out and connected to the external power supply, and finally the F-SMP memory clamp in the closed state is obtained.

[0112] 2. Characteristics Analysis

[0113] 2.1 Dynamic Mechanical Analysis (DMA)

[0114] This experiment is mainly used to reveal the changes in the mechanical properties of the material used in the clamp arm under dynamic load with time, temperature and frequency. During the test, the temperature adjustment is controlled by the program, and the mechanical response of the sample is observed by applying a slight stress. In this experiment, a dynamic mechanical analyzer (DMAQ800) produced by TAINSTRUMENTS, USA, was used to perform tensile tests on the samples.

[0115] The size of the clamp arm sample tested was 20mm in length, 5mm in width, and 2mm in height, and the frequency was set to 1Hz. During the test, the temperature of the sample started from 20℃ and gradually increased at a rate of 10℃ / min until it reached 120℃. The Dynamic Mechanical Analysis (DMA) test obtained the pure SMP and F-SMP (P50-50, the numbers represent Fe 3 O 4 The relationship between the storage modulus (E') and loss modulus (Tanδ) of the epoxy resin and the temperature. Figure 4 The change curves of storage modulus and loss modulus are shown.

[0116] analyze Figure 4 The data show that when the temperature exceeds Tg, SMP undergoes a transition from a glassy state to a rubbery state, and is more susceptible to deformation under an applied load. At room temperature, the storage moduli of P50-50 and pure SMP are 2.9 GPa and 1.7 GPa, respectively, indicating that Fe doping 3 O 4 The storage modulus of the composite material was improved by adding Fe 3 O 4 The composite material has good load-bearing capacity.

[0117] 2.2 Analysis of magnetic control performance

[0118] In this experiment, the inner magnetic field of the circular magnet installed in the storage space is used to drive the F-SMP memory gripper to achieve deformation. The magnetic induction intensity at different positions from the upper surface of the magnet is measured using a Gauss meter, and the upper surface of the magnet is defined as the initial position 0. Figure 5 The magnetic induction intensity distribution is shown.

[0119] According to the test results, it can be found that the magnetic induction intensity near the upper surface of the magnet is the largest (about 240mT), and the farther away from the upper surface of the magnet, the smaller the magnetic field intensity. At the same time, Comsol software is used to simulate the magnetic field distribution of the ring magnet, and the results are basically consistent with the measured data.

[0120] During the test, the closer the memory jaws are to the upper surface of the magnet, the larger the opening distance of the memory jaws. 3 O 4 The higher the content, the greater the opening distance of the memory jaws at the same distance from the magnet.

[0121] 2.3 Analysis of heating characteristics

[0122] This experiment studies the effect of the diameter of the resistance wire on the heating performance of the clamp arm in the memory clamp. The test uses nickel-chromium wires with diameters of 40, 50, 60, 70, and 80 μm to measure the change in the surface temperature of the clamp arm within 30 seconds. The experimental data obtained are as follows: Figure 6 shown.

[0123] analyze Figure 6 From the data, we can see that when the diameter of the resistance wire is 80μm, the heat generated within 30s is not enough for the F-SMP to reach Tg. As the diameter of the resistance wire decreases, the resistance increases, the heat generated by the resistance wire per unit length increases, the surface heating rate accelerates, and the maximum surface temperature also increases. When the diameter of the resistance wire is 40μm, the surface temperature of the F-SMP rises fastest, reaching Tg in only 2.2 seconds, and reaching 155℃ within 30 seconds. Therefore, the diameter of the resistance wire used in subsequent experiments is 40μm.

[0124] 3. Performance Test

[0125] 3.1 Response time

[0126] like Figure 7 As shown in the figure, this experiment defines three time parameters to characterize the dynamic response capability of the memory gripper: the time required to deform from the initial state T(0), the time required to reach the maximum deformation T(Max), and the recovery time T(R) required for the memory gripper to completely recover and close after power is turned on and the magnetic field is removed. The shorter these three times are, the faster the memory gripper responds.

[0127] During the experiment, the response time of the memory gripper was studied by controlling the variables. 3 O 4 The experimental data obtained are as follows: Figure 8 shown.

[0128] Figure 8 (a) When other parameters such as current, arm thickness, and arm width are fixed, the Fe 3 O 4 The three response times of the memory gripper after the content is increased. 3 O 4 As the content increases, T(0) increases from 3.2s (P10-90) to 5.8s (P 50-50) and then decreases to 4.3s (P 70-30), T(Max) decreases from 7.2s to 1.4s and then increases to 2.6s, and T(R) decreases from 9.4s to 6.2s and then increases to 7.8s; this is Fe 3 O 4The increase in content is the result of the game between the increase in temperature rise rate (favorable to deformation) and the increase in stiffness (unfavorable to deformation). Comprehensive experimental results: 50% content is the optimal parameter.

[0129] Figure 8 (b) shows that when the current increases from 0.05A to 0.25A, T(0) decreases from 9.4s to 1.0s, T(Max) decreases from 6.7s to 0.9s, and T(R) decreases from 12.4s to 3.2s. This is because the increase in current is conducive to increasing the heating speed of the memory gripper. In order to better control the heating speed, 0.2A current is the optimal parameter. Figure 8 (c) and Figure 8 The results of (d) show that as the arm width and thickness of the memory gripper increase, the three response times all increase, which indicates that the response capability of the memory gripper can be improved by reducing the arm width and thickness.

[0130] 3.2 Deformability

[0131] This study quantitatively studied the different Fe 3 O 4 The influence of Fe content and memory clamp arm size on the opening distance of F-SMP. The experimental method is: place the memory clamp at 0 mm above the magnet surface, apply power for 60 seconds to allow the deformation of the memory clamp to reach a steady state, and measure the opening distance of the memory clamp. The final opening distance is proportional to the Fe content. 3 O 4 The experimental results of the changes in content, arm width and arm thickness are as follows: Fig. 9 shown.

[0132] analyze Fig. 9 From part (a), we can see that when Fe 3 O 4 When the doping ratio of F-SMP is below 50%, the deformation distance increases with the increase of the content. However, when the content exceeds 50%, the deformation distance decreases. This may be due to the internal Fe 3 O 4 The agglomeration of nanoparticles will make the local material properties uneven, thus affecting the overall deformation capacity. Therefore, it can be concluded that Fe 3 O 4 Moderate doping of nanoparticles can improve the deformation ability of the material, but excessive doping will increase the rigidity of the material, thereby reducing its deformation ability. 3 O 4 The doping amount should be 50 wt%.

[0133] analyze Fig. 9 (b) and Fig. 9In part (c), it can be found that when the arm width of the memory gripper increases from 600μm to 1400μm, its opening distance decreases from 15.8mm to 9.7mm. When the arm thickness increases from 300μm to 700μm with a fixed arm width of 1000μm, the opening distance of the memory gripper decreases from 15.7mm to 11.7mm. Therefore, the opening distance of the memory gripper can be controlled by controlling the structural parameters of the gripper arm, so as to achieve precise grasping.

[0134] 3.3 Inertial distance

[0135] In order to study the gripping ability of the F-SMP memory gripper on fragile objects, this experiment defines the concept of "inertia distance". Fig.10 As shown in the figure, the inertial distance is the distance that the memory jaws continue to deform under residual heat after the current is disconnected. The larger the inertial distance, the easier it is to damage fragile objects. During the experiment, the power was kept on for 3 seconds at the maximum opening distance of the memory jaws, and then the power was turned off. Different parameters such as Fe 3 O 4 The influence of content, current and arm thickness on the inertial distance of F-SMP clamp arms. The experimental data obtained are as follows Fig.11 As shown,

[0136] analyze Fig.11 From the data in (a), we can see that as Fe 3 O 4 As the content increases, the inertial distance of the micro-memory gripper shows a trend of first increasing and then decreasing. Among them, the inertial distance of the F-SMP memory gripper with the lowest content is only 56μm, which has the ability to clamp fragile objects. Fig.11 As shown in the data in (b), when the current is low, the surface temperature of the F-SMP arm is low, and the inertial distance of the micro-memory gripper after power failure is short; as the current increases, the surface temperature of the F-SMP arm increases, and the residual heat after power failure causes the memory gripper to continue to deform. In the case of 0.25A, the inertial distance reaches 740μm, which is not suitable for grasping fragile objects. Analysis Fig.11 From the data in (c), we can see that the thicker the memory gripper arm, the smaller its inertia distance, demonstrating the excellent fragile object grasping capability of the micro-memory gripper.

[0137] like Fig.12 As shown, this experiment selected a solution with a smaller inertia distance to grasp the "fragile" soft tofu. During the experiment, the soft tofu could be grasped stably and was not damaged. This shows that the memory gripper of the present invention can be used to grasp fragile objects.

[0138] 3.4 Load-bearing capacity

[0139] In order to improve the load ratio of the memory gripper (load ratio = load weight / self weight), this experiment studied different parameters such as Fe by controlling the variable method. 3 O 4 The influence of content, arm thickness, arm number and arm width on the load-bearing capacity of memory grippers. The experimental results are as follows Fig.13 shown.

[0140] analyze Fig.13 From part (a), we can see that as Fe 3 O 4 When the content increases from 10% to 50%, the load ratio of the memory jaw increases from 96.5g to 194.0g. When the content is 70%, the load ratio of the memory jaw decreases and the memory jaw becomes more easily damaged. Fig.13 From parts (a)-(d), we can see that as the thickness, number and width of the arms in the memory gripper increase, the load of the memory gripper also increases, but due to the increase in deadweight, the load ratio first increases and then decreases. The results show that the load ratio of the four-arm memory gripper with a content of 50%, an arm thickness of 700μm, an arm width of 1mm and an arm length of 10mm is as high as 2380. Among them, the mass of the four-arm memory gripper itself is about 0.084g, and it can generate a tensile force of about 194.0g.

[0141] 3.5. Ability to manipulate magnetic objects

[0142] The temporary form of traditional magneto-actuated SMP memory grippers usually requires an external magnetic field to close, and they need to stay close to the magnet during the grasping and transfer process, which limits their ability to grasp magnetic objects. The memory gripper in this experiment only relies on the magnetic field when it is open (releasing the target object) and no longer relies on the magnetic field during the closing process (grasping the target object). Therefore, it can be used to capture and transfer magnetic objects with high flexibility. Fig.14 An image showing the memory gripper of the present invention grasping an N52 magnet.

[0143] 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. A multi-scale adaptive electrothermal magnetic driven gripper robot, which is used to grasp and transfer objects of different shapes and sizes between a picking space and a storage space; characterized by: A fixed magnetic field is provided in the storage space for driving the holding robot to release the target object and restore the shape; The multi-scale adaptive electrothermal magnetic driven gripping robot comprises: A memory clamp comprises a base and a plurality of curved clamp arms arranged in an annular manner below the base; the free ends of the clamp arms away from the base are close to each other; the clamp arms comprise a base and a heating unit embedded in the base; the base is made of a shape memory polymer filled with ferromagnetic material or permanent magnet particles; in a natural state, each clamp arm in the memory clamp is in a retracted state; A motion mechanism movably connected to a base of the memory clamp; An adjustable power supply, which is electrically connected to the heating unit in each of the clamp arms and is used to adjust the switch state and heating power of the heating unit; and A controller is electrically connected to the adjustable power supply and the motion mechanism; the controller includes a motion control unit and a thermal control unit; the motion control unit is used to issue instructions to the motion mechanism, thereby controlling the motion mechanism to drive the memory gripper to move freely in a specified space; the thermal control unit is used to issue instructions to the adjustable power supply, thereby achieving: (1) when picking up an object, a preset heating parameter mapping table is queried according to the ambient temperature of the picking space and the size of the target object, and then the heating unit is controlled to operate according to the specified heating power and heating time according to the query result, so that the temperature of each clamp arm is just lower than the glass transition temperature Tg when it recovers from the maximum expansion state to the expansion state consistent with the size of the target object, reaches a hardened state and grasps the target object; (2) when placing an object, the electric heating unit is first controlled to operate according to the maximum heating power so that the temperature of each clamp arm is higher than the glass transition temperature to complete the release of the target object. At this time, under the action of the fixed magnetic field, the free ends of each clamp arm after softening recover to the maximum expansion state; then the electric heating unit is controlled to stop working so that the clamp arm remains hardened in the maximum expansion state.

2. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 1, characterized in that: The clamping arm is an arc-shaped thin sheet or a bent multi-segment thin sheet; and / or The number of clamping arms in the memory clamp is not less than 2, and the structure is in a bionic hand grasping action; and / or The base material of the clamp arm is formed by mixing epoxy resin, epoxy resin curing agent and Fe3O4 particles in a mass ratio of 3:1:

4.

3. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 2, characterized in that: The heating unit comprises a resistance wire and an electrode; the resistance wire is located in the substrate and has a mesh structure; the electrode is electrically connected to the thermal control unit in the controller; and / or A rough texture is arranged on the inner side of the free end of each clamping arm in the memory clamping jaw.

4. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 3, characterized in that: A temperature sensor is also installed on the base of the memory clamp. The temperature sensor is electrically connected to the controller and is used to detect the ambient temperature around the memory clamp.

5. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 1, characterized in that: The motion mechanism adopts a multi-axis mechanical arm or a truss robot.

6. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 1, characterized in that: The ambient temperature of the object-taking space and the object-storing space is lower than the glass transition temperature Tg of the shape memory polymer used in the clamp arm; and / or A permanent magnet for generating a required fixed magnetic field is arranged in the storage space.

7. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 1, characterized in that: The heating parameter mapping table is used to characterize the values ​​of heating power and heating duration that meet the minimum power consumption constraint when the memory gripper is restored from the maximum expansion state to the state of the specified opening distance under each ambient temperature T; The opening distance corresponds to the size of the target object when the clamping arm of the memory clamp can maintain a stable clamping effect in different contraction states.

8. The multi-scale adaptive electrothermal magnetic driven gripper robot according to claim 7, characterized in that: The method for constructing the heating parameter mapping table is: S1: Divide the working temperature range of the multi-scale adaptive electrothermal magnetic driven gripper robot into multiple different temperature intervals, and divide the heating power of the heating unit into multiple gears; S2: Test the time required to heat the memory jaws from the hardened maximum expansion state to the softened fully retracted state at the lowest temperature and the highest gear state, and record it as the maximum heating time; S3: Set the ambient temperature of the test environment to the specified minimum temperature range, and then perform the following test tasks: S31: setting the heating power to the lowest gear, increasing the heating time at equal intervals, and recording the opening distance of the memory clamp when the memory clamp is finally restored to hardening after being heated for different time periods; S32: increasing the gear of the heating power, repeating step S31, testing and recording the opening distance of the memory jaws when the memory jaws are finally restored to hardening under different gears and different heating times; S33: setting the ambient temperature of the test environment to a higher temperature range, repeating steps S31-S32, testing and recording the opening distance of the memory jaws when the memory jaws are finally restored to hardening under different ambient temperatures, different gears and different heating times; S4: Based on the data recorded in the test task, a feature vector consisting of a series of associated values ​​of ambient temperature T, heating power W, heating time t and opening distance D is generated: recorded as (T, P, t, D); and the original vector set A is obtained; S5: multiple vectors with the same T value and D value in the original vector set are selected to form a redundant vector set, and then multiple redundant vector sets are obtained; S6: Calculate the power consumption W of each feature vector in each redundant vector set, and delete the feature vector with the smallest power consumption: W = P·t; S7: Delete the feature vectors in the original vector set that are the same as the redundant vector sets, and then construct a heating parameter mapping table for characterizing the P and t values ​​corresponding to each set of T and D values ​​according to the remaining feature vectors of the original vector set.

9. A memory clamp, characterized in that: It includes a base and a plurality of curved clamp arms arranged in a ring shape below the base; the free ends of the clamp arms away from the base are close to each other and in a retracted state; the clamp arms include a base and a heating unit pre-buried in the base; the base is made of a shape memory polymer filled with ferromagnetic material or permanent magnet particles.

10. The memory clamp according to claim 9, characterized in that: The preparation method is as follows: (1) A femtosecond laser processing system is used to process a number of grooves on the silicone template that match the shape of the clamping arms in the memory clamp. The processing parameters are: The laser wavelength is 800nm, the pulse width is 104fs, and the frequency is 1kHz; the scanning strategy is set to linear scanning, the scanning speed is 20mm / s, and the scanning interval is 60μm; (2) mixing epoxy resin monomer and epoxy resin curing agent for synthesizing SMP material in a ratio of 3:1, adding no less than 20%wt of Fe3O4 particles thereto, stirring evenly and performing vacuum degassing to obtain the desired matrix material; (3) filling a portion of the matrix material into the groove of the silicone template in a vacuum environment, and then placing the resistance wire and the electrode as the heating unit into the groove after assembly, and continuing to fill the matrix material until the groove is filled, and scraping off the excess material; (4) curing the silicone mold filled with the matrix material and the heating unit at a temperature not lower than 80° C. for 2 h, and obtaining the desired clamp arm after demolding; (5) Each clamping arm is fixedly connected to a pre-prepared base according to a specified arrangement to obtain the required memory clamping jaws.

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