Composite flexible grabbing device and grabbing method based on magnetic control intelligent material

Abstract

The invention discloses a composite flexible grabbing device and method based on a magnetic control intelligent material. The invention relates to a device for driving a magnetic control 4D printing soft intelligent gripper and a gripping method, and the device and the method are suitable for driving the soft gripper made of a magnetic control intelligent material to be unfolded and folded, and are suitable for flexibly gripping soft or fragile objects. The device comprises a connecting part, a telescopic device, a magnetic field generating device, a clamping device and a magnetic control intelligent material executing structure. The magnetic field generating device comprises a coil used for driving the 4D printing soft gripper, a cylindrical pole shoe, an annular pole shoe, a push rod motor, a magnetorheological fluid filling composite structure and a touch sensor. When the gripper moves to the position above an object to be grabbed, the push rod motor drives the cylindrical pole shoe to extend downwards until the force sensor detects a signal, the cylindrical pole shoe stops moving, the coil is powered on, at the moment, the magnetorheological fluid filling composite structure and the object to be grabbed form a coating effect, the rigidity is increased, and closed auxiliary grabbing is achieved. And the magnetic control 4D printing gripper contracts to realize force closing gripping.

Description

Technical Field

[0001] The invention relates to the technical field of soft robots, and in particular to a magnetically controlled soft gripper assembly. Background Art

[0002] With the rapid development of the field of humanoid robots, new requirements have been put forward for simplifying the complex mechanisms of space use and increasing their reliability. Taking the dexterous humanoid robot hand as an example, the traditional robot hand uses rigid components and kinematic pairs to form a kinematic chain, and uses actuators such as motors and artificial muscles to cooperate with transmission parts such as connecting rods, gears or tendons to achieve movement. Existing rigid robot hands generally have some weaknesses: in order to achieve multi-degree-of-freedom coordinated movement, rigid manipulators generally need to install a large number of motors at the joints. Integrating a large number of active degrees of freedom under strict size restrictions will put extremely demanding requirements on the design and selection of motors and reducers. Underactuated and coupled mechanisms can alleviate these difficulties to a certain extent, but their structures are still complex and fragile; in order to grasp soft and fragile objects or avoid rigid impact, it is necessary to integrate more position and force sensors for the rigid hand and realize multi-degree-of-freedom compliant control, which puts higher requirements on the control algorithm and greatly increases the complexity of the system. It is urgent to invent a flexible soft gripper that is simple to control, easy to use and low in cost.

[0003] The response mechanism contained in 4D printing is very close to the driving deformation mechanism of organisms. Therefore, in recent years, more and more bionic intelligent material structure systems have been manufactured by 4D printing. The development of 4D printing technology, especially the expansion of various intelligent material systems, has greatly expanded the application space of 4D printing. Soft robots made by 4D printing are generally simple and light in structure, have good environmental adaptability, low cost, and better human-computer interaction and safety. Compared with rigid robot hands, soft-structured robot hands are more suitable for grasping fragile and deformable objects. These hands can achieve smooth grasping and operation of complex contours and soft and fragile objects in unstructured environments; achieve safe human-computer interaction, and endure collisions and impacts. However, as shown in the publication number CN118085570A, the current magnetically controlled 4D printed gripper has the problems of insufficient grasping force and difficulty in applying magnetic field, which limits its application scenarios. Therefore, there is an urgent need for a composite grasping method that integrates magnetic field generation, magnetically controlled intelligent structure and tactile sensing. Summary of the invention

[0004] The purpose of the present invention is to fill the gap in the application of variable stiffness 4D printed soft grippers in humanoid robots and robotic arms to achieve grasping, and to solve the problem of limited application scenarios of 4D printed soft grippers.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A composite flexible grasping device and grasping method based on magnetically controlled intelligent materials provided by the present invention

[0007] The soft gripper comprises: a 4D printed soft gripper, an upper fastening end cover, a lower fastening end cover, a coil, an annular pole shoe, a cylindrical pole shoe, a magnetorheological fluid filled composite structure, an upper flange, a lower flange, and a telescopic device.

[0008] The upper fastening end cover and the lower fastening end cover are connected by bolts, and the gap between the two forms a cone angle. The 4D printed soft gripper can be clamped by adjusting the tightness of the bolts.

[0009] The 4D printed soft gripper is made by 4D printing technology, and has opposite magnetic poles at the clamped end and the end. Under the magnetic field provided by the magnetic field generating device, the annular pole shoe, and the cylindrical pole shoe, it performs opening and closing actions to achieve grasping, and is the main actuator of the gripper.

[0010] The annular pole shoe is a rotating body structure cut into two halves, which is radially fixed by pin connection, key connection, and mortise and tenon connection, and axially fixed by an upper fastening end cover, bolts, and a lower flange for magnetic conduction.

[0011] The telescopic device is connected to the cylindrical pole shoe, and the telescopic device part that can move relatively between the telescopic device and the cylindrical pole shoe is fixed to the upper flange and the lower flange, and the two flanges are connected by a bolt group.

[0012] The magnetorheological fluid-filled composite structure is connected to the cylindrical pole shoe and moves together. The magnetorheological fluid-filled composite structure wraps the magnetorheological fluid material. When it is attached to the surface of the object and the magnetic field is passed, the rigidity is significantly increased to form a closed gripping effect. At the same time, the sensor attached to it can play a role in tactile perception and auxiliary gripping.

[0013] The magnetic field generating device includes a pole shoe and a coil. The coil is wound around the pole shoe in a clockwise direction. The number of turns of the coil is 2000. When the coil is energized, it can generate a magnetic field guided by a magnetic circuit. The magnitude and direction of the magnetic field strength can be controlled by adjusting the magnitude and direction of the energized current.

[0014] The composite flexible grasping method based on magnetically controlled smart materials is as follows:

[0015] Step S1, the gripper moves to the top of the object to be grasped, and the cylindrical pole shoe slowly moves downward until the tactile sensor on the magnetorheological fluid-filled composite structure obtains a signal of contact with the object to be grasped and the magnetorheological fluid-filled composite structure and the object to be grasped produce a covering effect, and then stops moving;

[0016] Step S2, power is supplied to enable the magnetic field generating device to generate a magnetic field, the annular pole shoe generates a magnetic field that repels the upper end of the 4D printed structure, and the cylindrical pole shoe generates a magnetic field that attracts the lower end of the 4D printed structure, so as to guide the gripper to close and cause the magnetorheological fluid in the magnetorheological fluid-filled composite structure to change its stiffness to assist in grasping;

[0017] Step S3, after the object is grasped to the designated position, power is turned on to enable the magnetic field generating device to generate a magnetic field, the annular pole shoe generates a magnetic field that attracts the upper end of the 4D printed structure, and the cylindrical pole shoe generates a magnetic field that repels the lower end of the 4D printed structure, thereby guiding the gripper to open and release the object;

[0018] Step S4, turn off the magnetic field generating device, and move the cylindrical pole shoe upward until it returns to its original position, waiting for the next capture. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a half-section schematic diagram of a composite flexible gripping device based on magnetically controlled intelligent materials, and the figure numbers are explained as follows: 1-upper flange; 2-upper bolt; 3-lower flange; 4-telescopic device; 5-cylindrical pole shoe; 6-magnetic field generating device; 7-lower bolt; 8-left annular pole shoe; 9-upper fastening end cover; 10-lower fastening end cover; 11-4D printed soft gripper; 12-magnetorheological fluid filled composite structure; 13-right annular pole shoe; 14-fastening screw.

[0020] Figure 2 This is a top view schematic diagram of a composite flexible grasping device based on magnetically controlled smart materials.

[0021] Figure 3 This is an axonometric diagram of an unclamped 4D printed soft gripper of a composite flexible gripping device based on magnetically controlled smart materials.

[0022] Figure 4 Schematic diagram of a composite flexible grasping device based on magnetically controlled smart materials when opened.

[0023] Figure 5 This is a schematic diagram of a composite flexible grasping device based on magnetically controlled smart materials when it is closed and grasping an object.

[0024] Figure 6 This is a partial enlarged view of the magnetorheological fluid-filled composite structure in a composite flexible grasping device based on magnetically controlled intelligent materials, which fits the surface of the grasped object. DETAILED DESCRIPTION

[0025] The structure and printing steps of the present invention are further described below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0026] The purpose of the present invention is to provide a composite flexible grasping device based on magnetically controlled intelligent materials, which can improve the grasping success rate while ensuring that the grasped object is not damaged.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 As shown, it describes the structural schematic diagram of the present invention, and the device of the present invention includes an upper flange 1; an upper bolt 2; a lower flange 3; a telescopic device 4; a cylindrical pole shoe 5; a coil 6; a lower bolt 7; a left annular pole shoe 8; an upper fastening end cover 9; a lower fastening end cover 10; a 4D printed soft gripper 11; a magnetorheological fluid-filled composite structure 12; a right annular pole shoe 13; and a fastening screw 14. The material of the 4D printed soft gripper can be a magnetically responsive shape memory polymer. The 4D printed soft gripper is placed in the conical gap formed by the upper and lower fastening end covers, and the gradient clamping is achieved by adjusting the bolt preload to ensure that the contact stress between the gripper root and the end cover conical surface is evenly distributed.

[0029] The annular pole shoe is manufactured by soft casting and machining, radial positioning is achieved through mortise and tenon joints, and the axial direction is fixed by the bolt group of the upper fastening end cover and the lower flange, and the air gap of the magnetic circuit is controlled within 0.5mm.

[0030] The cylindrical pole shoe is made of magnetic stainless steel and connected to the upper / lower flange through a linear guide. Its moving stroke is controlled by a telescopic device (preferably a micro electric push rod), with a maximum stroke of 50mm and an adjustable speed range of 0.1-5mm / s.

[0031] The magnetic field generating device adopts a symmetrical layout of double annular pole shoes, with 2000 turns of 0.5mm enameled copper wire wrapped around the pole shoes, a coil resistance of 15Ω, a rated current of 2A, and a maximum magnetic field strength of up to 1.2T.

[0032] The magnetorheological fluid-filled composite structure 12 is made of silicone rubber (Shore hardness 30A), filled with carbonyl iron powder-based magnetorheological fluid (volume fraction 40%), and integrated with a PVDF piezoelectric film tactile sensor array (resolution 5mm×5mm) on the outer surface, with a signal sampling frequency of 100Hz.

[0033] The control module integrates an H-bridge drive circuit, supports bidirectional current regulation (-2A to +2A), has a response time of <50ms, and achieves precise control of magnetic field strength through a PID algorithm.

[0034] The fetch method is implemented as follows:

[0035] In the positioning phase, the robot arm drives the gripper to move to 20 mm above the target object, and the telescopic device pushes down the cylindrical pole shoe at a speed of 2 mm / s. When the tactile sensor detects a pressure threshold greater than 0.3 N, a stop signal is triggered, and the magnetorheological fluid-filled composite structure 12 generates a 15% compression deformation to form a preliminary coating.

[0036] During the grasping stage, a forward current of 1.5A is passed through the coil to generate a composite magnetic field: the annular pole shoe and the N pole at the upper end of the gripper form a 0.8T repulsive field, driving the root of the gripper to bend; the cylindrical pole shoe and the S pole at the end of the gripper form a 1.0T attractive field, causing the end of the gripper to close. The cylindrical pole shoe and the N pole at the end of the gripper form a 1.0T attractive field, causing the end of the gripper to close.

[0037] During the release phase, the current is reversed to -1.0A, the magnetic field polarity is reversed, and the annular pole shoe turns into a 0.5T attraction field to prompt the gripper to unfold. The cylindrical pole shoe generates a 0.3T repulsion field to assist separation. When the magnetorheological fluid field strength drops to 0.1T, the liquid properties are restored, and the stiffness of the magnetorheological fluid-filled composite structure 12 drops back to 0.5Mpa.

Claims

1. A composite flexible grasping device based on magnetically controlled smart materials, characterized in that: include: Connecting parts, telescopic devices, magnetic field generating devices, clamping devices, and magnetically controlled smart material execution structures; The connecting components include: an upper flange (1), an upper bolt (2), a lower flange (3), and a lower bolt (7); and are used to fix the telescopic device (4) and the magnetic field generating device to ensure that the fixed parts do not move relative to each other. The magnetic field generating device comprises: a cylindrical pole shoe (5), a coil (6), a left annular pole shoe (8), and a right annular pole shoe (13); the cylindrical pole shoe (5) is connected to a telescopic device, and the telescopic device drives the movement of the cylindrical pole shoe; The clamping device comprises: an upper fastening end cover (9), a lower fastening end cover (10), and a fastening bolt (14), wherein the upper fastening end cover (9) is used for axial fixation of the annular pole shoe, the upper fastening end cover (9) and the lower fastening end cover (10) are connected by 3 to 6 fastening bolts (14), the radial fitting surfaces of the upper fastening end cover (9) and the lower fastening end cover (10) form a conical structure, and the cone angle is 3° to 90°. Under the locking action of the fastening bolts, the radial fitting surfaces of the upper fastening end cover (9) and the lower fastening end cover (10) clamp and fix the 4D printed soft gripper (11); The magnetically controlled intelligent material execution structure comprises: a 4D-printed soft gripper (11) and a magnetorheological fluid-filled composite structure (12); the 4D-printed soft gripper (11) is made of the materials and processes used in magnetorheological 4D printing, and the magnetic poles at the upper and lower ends are respectively north and south poles, and can be attracted by the magnetic field generated by the left annular pole shoe (8), the right annular pole shoe (13) and the cylindrical pole shoe (5); the magnetorheological fluid-filled composite structure (12) undergoes a change in stiffness under the magnetic field guided by the cylindrical pole shoe (5).

2. According to claim 1, a composite flexible gripping device based on magnetically controlled smart materials is characterized in that The telescopic device adopts a screw stepping motor, a screw servo motor, a push rod motor, a cylinder and a hydraulic cylinder to realize the axial telescopic extension of the columnar pole shoe (5).

3. According to claim 1, a composite flexible grasping device based on magnetically controlled smart materials is characterized in that: The left annular pole shoe (8), the right annular pole shoe (13) and the cylindrical pole shoe (5) are made of iron, silicon steel and soft magnetic alloy, and have the function of guiding the magnetic field to the required space and driving the 4D printed soft gripper to open and close.

4. According to claim 1, a composite flexible grasping device based on magnetically controlled smart materials is characterized in that: The coil (6) is made of 1000 to 3000 turns of 0.5 mm enameled copper wire.

5. The composite flexible grasping device based on magnetically controlled smart materials according to claim 1 is characterized in that: The magnetorheological fluid filled composite structure (12) is a capsule-shaped structure composed of a film with a thickness of 0.2 mm to 1.5 mm. The magnetorheological fluid filled composite structure (12) is filled with magnetorheological fluid and can adaptively adjust its own shape according to the shape of the grasped object to adapt to a partial area of ​​the grasped object domain; the magnetorheological fluid built into the magnetorheological fluid filled composite structure (12) can change its stiffness under the magnetic field guided by the cylindrical pole shoe (5), thereby assisting grasping; the outer side of the magnetorheological fluid filled composite structure (12) (the side that is directly in contact with the grasped object) is covered with a tactile sensor, including an electronic skin and a force sensor, which is coated on the magnetorheological fluid filled composite structure (12) using micro-nano processing technology, multi-layer composite structure construction, and thin film coating technology to achieve feedback of force, touch, and shape; the film of the magnetorheological fluid filled composite structure (12) is made of silicone, latex, polylactic acid, polyvinyl chloride, and vinyl chloride materials, all of which have strong plastic deformation capabilities.

6. The composite flexible grasping device based on magnetically controlled smart materials according to claim 1, characterized in that: The number of 4D printed soft grippers (11) is 2 to 72, with a width of 2 to 30 mm, a length of 30 to 120 mm, and a thickness of 1 to 6 mm. They are distributed in the circumferential direction of the clamping device and are shaped like petals or anemones.

7. A composite flexible grasping grasping method based on magnetically controlled smart materials, characterized in that: A composite flexible gripping device based on magnetically controlled smart materials as claimed in any one of claims 1 to 6 is provided; the method of use comprises the following steps: Step S1, the gripper moves to the top of the object to be grasped, and the cylindrical pole shoe slowly moves downward until the tactile sensor on the magnetorheological fluid-filled composite structure obtains a signal of contact with the object to be grasped and the magnetorheological fluid-filled composite structure and the object to be grasped are in contact, and then the gripper stops moving; Step S2, power is supplied to enable the magnetic field generating device to generate a magnetic field, the annular pole shoe generates a magnetic field that repels the upper end of the 4D printed structure, and the cylindrical pole shoe generates a magnetic field that attracts the lower end of the 4D printed structure, so as to guide the gripper to close and cause the magnetorheological fluid in the magnetorheological fluid-filled composite structure to change its stiffness to assist in grasping; Step S3, after the object is grasped to the designated position, power is turned on to enable the magnetic field generating device to generate a magnetic field, the annular pole shoe generates a magnetic field that attracts the upper end of the 4D printed structure, and the cylindrical pole shoe generates a magnetic field that repels the lower end of the 4D printed structure, thereby guiding the gripper to open and release the object; Step S4, turn off the magnetic field generating device, and move the cylindrical pole shoe upward until it returns to its original position, waiting for the next capture.

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