A wire-driven multi-mode folding gripper with flexible joints

Abstract

The application discloses a wire-driven multi-mode folding and unfolding gripper with a flexible joint, which has a folding and unfolding gripping part composed of three X-shaped scissors units in a circumferential direction, and adjacent scissors units are connected through connecting assemblies. The bottom of the folding and unfolding gripping part is connected with the flexible joint, and in an initial state, the whole is in a folded state under the action of a torsional spring. Motion control of the application is realized through three driving wires in the circumferential direction, including bending motion control that can pass through a narrow and curved pipeline, capture motion control after reaching a target position, and locking control after successful capture. Meanwhile, the application proposes a driving wire control strategy to realize the control and switching of various motion modes of the gripper. In summary, the application has a small size in the folded state to pass through a narrow cavity environment, and the operation task is completed by virtue of the reconstruction of the mechanism motion mode and the change of the driving wire control law.

Description

Technical Field

[0001] This invention belongs to the field of mechanical technology and relates to a wire-driven multi-mode unfolding gripper with flexible joints. Background Technology

[0002] With the development of medical technology, surgery through natural body cavities has gradually become the preferred treatment for many diseases due to its advantages such as no incision, minimal invasiveness, and rapid recovery. In certain surgical fields, such as endoscopic biopsy and foreign body removal from the digestive system, the procedure requires capturing and removing tissue or foreign bodies from the lesion site. Currently, endoscopic biopsy often involves endoscopic exploration. Once the endoscope reaches the lesion site through the natural body cavity, biopsy forceps are then inserted through the biopsy port within the endoscope to obtain the lesion tissue. This frequent instrument changes increase the difficulty and time required for the procedure. Furthermore, because biopsy forceps typically have a scissor-like clamp structure, their ability to grasp biopsy tissue is limited, resulting in a relatively small volume of tissue that can be retrieved, which is not conducive to subsequent pathological analysis. Therefore, designing a novel operating mechanism that can guide within the body's natural cavities and capture the target object after reaching the target location, capable of multi-mode motion operation and reliably capturing large-volume lesions, has significant economic and social value. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a wire-driven multi-mode folding and grasping device with flexible joints. Through wire-driven control, it can move within narrow cavity environments and capture pathological tissues upon reaching the target location.

[0004] The present invention relates to a wire-driven multi-mode folding and grasping device with flexible joints, comprising a folding and grasping portion, flexible joints, and a drive wire.

[0005] The folding and gripping section includes three circumferentially distributed scissor units, which are cross-hinged by two connecting rods in an X shape, and a return torsion spring is installed at the hinge position; the folding and gripping section includes three circumferentially distributed X-shaped scissor units, which are cross-hinged by two connecting rods, and a return torsion spring is installed at the hinge position.

[0006] In adjacent scissor lift units, the top and bottom ends are respectively connected by a first connecting component and a second connecting component; the first connecting component and the second connecting component are connected to the scissor lift unit through two joints with coplanar axes to form a rotating pair.

[0007] The flexible joint assembly has an upper connecting platform at the top, which is connected to three second connecting components via three circumferential connecting rods to form a rotating pair, and a return torsion spring is installed at the connection position. The flexible joint assembly has a lower connecting platform at the bottom, and a connector for a push guide is designed on the bottom surface of the lower connecting platform; a flexible joint is designed between the upper and lower connecting platforms.

[0008] The drive wire consists of three wires, with their output ends fixed to three first connecting components. They are then guided downwards through the guide holes on the first connecting components and the guide holes in the second connecting components, and finally pass through the bottom connector of the flexible joint component and enter the push guide tube. They are then connected to their respective drivers inside the push guide tube.

[0009] The control strategy of the wire-driven multi-mode unfolding gripper with flexible joints in this invention includes direction control and capture control. Direction control involves driving three drive wires via an actuator, ensuring that the force exerted by the drive wires is less than the resistance of the return torsion spring in the unfolding gripper section, but greater than the force required for the flexible joint to bend, thus causing the flexible joint to bend. By controlling the three drive wires, the flexible joint achieves bending motion of the unfolding gripper section in any plane. Capture control involves synchronously driving the three drive wires, ensuring that the force exerted by the drive wires on the unfolding gripper section is greater than the resistance of the return torsion spring, causing the unfolding gripper section to gradually unfold under the synchronous action of the three drive wires. Furthermore, the three drive wires are driven with different forces, causing the flexible joint to bend.

[0010] The aforementioned directional control enables the gripper to navigate through narrow and curved pipes; upon reaching the target location, it switches to capture control to capture the target object; after capture, it switches back to directional control to retrieve the target object.

[0011] The advantages of this invention are:

[0012] 1. The present invention has a flexible joint wire-driven multi-mode folding and unfolding grasper with variable external dimensions. In the folded state, it has a smaller external dimension to pass through narrower cavity environments. After reaching the target position, the mechanism can unfold to capture pathological tissue.

[0013] 2. The present invention has a flexible joint-driven multi-mode folding gripper with flexible joints that can actively control the bending direction. By controlling the active guidance of the flexible joints, the designed gripper can be actively guided in folding and bifurcated cavity positions, helping it to pass through such difficult cavity environments.

[0014] 3. Corresponding drive wire control strategies are proposed for different motion modes of the invented gripper. Based on the two different drive wire control strategies proposed, the control and switching of multiple motion modes required by the invented mechanism can be realized.

[0015] 4. The present invention is a wire-driven multi-mode folding and grasping device with flexible joints. It can advance the catheter in the natural cavity by pushing it. By reconstructing the mechanism's motion mode and changing the control law of the driving wire, it can achieve two different operation tasks, which greatly simplifies the implementation process of traditional transoral surgery and reduces the operation time. In the future, it has broad application prospects in the fields of tissue biopsy acquisition through the natural cavity environment of the human body and foreign body capture in the human gastrointestinal tract. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the wire-driven multi-mode unfolding gripper with flexible joints of the present invention.

[0017] Figure 2 This is a schematic diagram of the scissor unit in the wire-driven multi-mode folding and unfolding gripper with flexible joints of the present invention;

[0018] Figure 3 This is a schematic diagram of the unfolding and grasping part in the wire-driven multi-mode unfolding and grasping grasper with flexible joints of the present invention.

[0019] Figure 4 This is a schematic diagram of the first connecting component in the filament-driven multi-mode folding and unfolding gripper with flexible joints of the present invention;

[0020] Figure 5 This is a schematic diagram of the second connecting component in the filament-driven multi-mode folding and unfolding gripper with flexible joints of the present invention;

[0021] Figure 6 This is a schematic diagram of the flexible joint component in the filament-driven multi-mode unfolding gripper with flexible joints of the present invention.

[0022] Figure 7 This is a schematic diagram showing the installation position of the third connecting component and the reset torsion spring in the wire-driven multi-mode folding and unfolding gripper with flexible joints of the present invention.

[0023] Figure 8 This is a schematic diagram of the initial retracted state of the wire-driven multi-mode unfolding gripper with flexible joints of the present invention.

[0024] Figure 9 This is a schematic diagram of the bending guide motion of the wire-driven multi-mode folding and unfolding gripper with flexible joints according to the present invention.

[0025] Figure 10 This is a schematic diagram of the unfolded state of the wire-driven multi-mode unfolding gripper with flexible joints of the present invention.

[0026] Figure 11 This is a schematic diagram of the target capture of the wire-driven multi-mode unfolding grasper with flexible joints according to the present invention.

[0027] Figure 12This is a schematic diagram of the wire-driven multi-mode unfolding gripper with flexible joints of the present invention gripping a target object;

[0028] Figure 13 This is a block diagram of the control strategy for the flexible joint-driven multi-mode unfolding gripper of the present invention under different motion modes.

[0029] In the picture:

[0030] 1-Scissor lift mechanism unit; 2-Flexible joint assembly; 3-First connecting assembly

[0031] 4-Second connecting component 5-Third connecting component 6-Drive wire

[0032] 101-Connecting rod; 201-Upper connecting platform; 202-Flexible joint

[0033] 203-Lower connecting platform; 201a-Vertical connecting surface; 201b-Third guide hole

[0034] 203a - Connector; 203b - Fourth Guide Hole; 203c - Fifth Guide Hole 301-Connector A; 302-Connector B; 303-First guide hole

[0035] 401-Connector C 402-Connector D 403-Connector E

[0036] 404 - Second Guide Hole Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings:

[0038] like Figure 1 As shown, the present invention discloses a wire-driven multi-mode folding and unfolding gripper with flexible joints, comprising three scissor mechanism units 1, a flexible joint assembly 2, a first connecting assembly 3, a second connecting assembly 4, a third connecting assembly 5, and a driving wire 6, as follows. Figure 1 As shown,

[0039] The three scissor mechanism units 1 have the same structure, such as Figure 2 As shown, each component consists of two X-shaped intersecting connecting rods 101. The two connecting rods 101 are designed with a hinge at their center, forming a rotating pair at the hinge. Furthermore, the connecting rods 101 in the scissor mechanism unit are designed as arc-shaped rods with their outer arc surfaces facing the same direction.

[0040] The three scissor mechanism units 1 of the above structure are evenly distributed circumferentially, and the included angle between the motion planes of adjacent scissor mechanism units 1 is 60°, as shown below. Figure 3As shown, the three scissor lift mechanism units 1 are connected circumferentially to the second connecting component 4 via the first connecting component 3, and the outer arc surface of the connecting rod 101 in each scissor lift mechanism unit 1 faces outward, so that the whole can better adapt to the environment of the circular inner wall of the natural cavity.

[0041] The first connecting component has three columnar joints on its circumference, such as... Figure 4 As shown, the three connectors are designated as two connectors A301 and one connector B302. Connecting holes are coaxially formed on the two connectors A301, with the included angle between the axes of the connecting holes being 120°. Connector B302 has a first guide hole 303, the axis of which is perpendicular to the plane containing the axes of the two connecting holes and passes through the angle bisector of the included angle between the axes of the two connecting holes.

[0042] The structure of the second connecting component 4 is similar to that of the first connecting component 3, such as... Figure 5 As shown, the device has four columnar connectors, designated as two connectors C401, one connector D402, and one connector E403. Connecting holes are coaxially formed on the two connectors C401, with the axes of these holes forming an angle of 120°. A second guide hole 404 is coaxially formed on connector D402, with its axis perpendicular to the plane containing the axes of the two connecting holes and passing through the angle bisector of the angle between their axes. Connector E403 is located at the angle between connectors C401 and D402, and has a connecting hole with its axis perpendicular to the second guide hole 404, forming a 30-degree angle with the axis of connector C401.

[0043] like Figure 1 As shown, the first connecting component 3 and the second connecting component 4 are arranged in pairs, longitudinally, and are used to connect two adjacent scissor mechanism units 1, with the same connection method. In the two connecting components in the same group, the first connecting component 3 is connected to the top of the inner connecting rod 101 and the top of the outer connecting rod 101 in the adjacent scissor mechanism unit 1 through two joints A301, forming a revolute joint; the second connecting component 4 is connected to the bottom of the outer connecting rod 101 and the top of the inner connecting rod 101 in the adjacent scissor mechanism unit 1 through two joints C401, forming a revolute joint; finally, the three scissor mechanism units 1 are connected in pairs to form an integral unfolding and grasping part, which has 1 degree of freedom of motion and can achieve stable and reliable unfolding and retracting movements.

[0044] like Figure 6As shown, the flexible joint assembly 2 includes an upper connecting platform 201, a flexible joint 202, and a lower connecting platform 203. The flexible joint 202 is a cylindrical rubber material with approximately linear elastic properties, allowing it to maintain its shape without external force. The top and bottom surfaces of the flexible joint 202 are respectively connected and fixed to the bottom surface of the upper connecting platform 201 and the top surface of the plate-shaped lower connecting platform 203. The upper connecting platform 201 has three vertical connecting surfaces 201a spaced at equal angles on its upper circumference; simultaneously, the bottom surface of the upper connecting platform 201 has three third guide holes 201b spaced at equal angles on its circumference. A cylindrical connector 203a is fixedly installed on the bottom surface of the lower connecting platform 203 for connecting a push guide tube; simultaneously, the lower connecting platform 203 has three fourth guide holes 203b spaced at equal angles on its circumference. Furthermore, three fifth guide holes 203c are spaced at equal angles on the top of the connector 203a.

[0045] The aforementioned flexible joint assembly 2 is connected to the unfolding and grasping part via the third connecting assembly 5. The third connecting assembly 5 consists of three straight rods, one end of which is connected to the joints E403 in the three second connecting assemblies 4 to form a revolute joint, and the other end is connected to the three vertical connecting surfaces 201a circumferentially on the upper connecting platform 201 to form a revolute joint, as shown below. Figure 1 As shown; and after the above connection, the first guide hole 303, the second guide hole 404, the third guide hole 201b, the fourth guide hole 203b and the fifth guide hole 203c are circumferentially aligned.

[0046] In the above structure, a torsion spring mounting slot is designed at the hinge position between the third connecting component 5 and the second connecting component 4 to install a reset torsion spring, such as... Figure 7 As shown; the two ends of the return torsion spring are connected to the third connecting assembly 5 and the second connecting assembly 4, respectively. Simultaneously, in the three scissor mechanism units 1, return torsion springs are installed at the hinge positions of the two connecting rods 101, as shown... Figure 2 As shown; the two ends of the return torsion spring are fixed to the two connecting rods 101 respectively. Thus, through the action of the two return torsion springs, the folding and grasping part can maintain its folded shape without external force intervention. At this time, the first connecting component 3 and the second connecting component 4 in the circumferential direction are at the position of minimum circumferential diameter, thus the overall folding and grasping part structure has a relatively small geometric dimension, such as... Figure 8 As shown.

[0047] The posture and grasping operation control of the aforementioned unfolding and grasping section are achieved through three drive wires 6 to complete the required task. For example... Figure 1 As shown, the output ends of the three drive wires 6 are fixed at the rope holes of the first connecting component 3 and positioned in the first connecting component 3; then the three drive wires 6 pass downward through the first to fifth guide holes in sequence, are guided by each guide hole and enter the interior of the connector 203a, and finally enter the push guide tube, and are connected to their respective drivers through the push guide tube.

[0048] The control strategy of the filament-driven multi-mode folding and unfolding grasper with flexible joints in this invention includes direction control and unfolding and retraction control strategies, specifically:

[0049] like Figure 8 The diagram shows the initial position of the wire-driven multi-mode folding gripper with flexible joints of the present invention. In the initial state, the three drive wires 6 are in a relaxed state. Under the restoring force of each reset torsion spring, the overall gripper is in a retracted state, and the designed flexible joint 202 is in an initial unbent state under its own restoring force.

[0050] When the gripper needs to pass through narrow and curved passages inside the human body, its movement can be achieved through a directional control strategy. This strategy involves driving three drive wires 6 via an end effector. Due to the resistance of the return torsion spring in the unfolding gripping section, the force exerted by the drive wires 6 on the mechanism is insufficient to overcome this resistance. Therefore, the length of the three drive wires 6 within the unfolding gripping section remains unchanged, and the section remains in a retracted state. Because the flexible joint 202 has low stiffness, the driving force required for its bending is lower than the resistance required for the unfolding gripping section to overcome the return torsion spring's unfolding resistance. Consequently, the flexible joint 202 will bend under the force of the three drive wires 6. Figure 9 As shown. Since the flexible joint 202 is a cylindrical structure made of rubber material, its axial direction is incompressible, and therefore its motion can be analyzed and modeled using an isocurvature model. Figure 9 As can be seen, the resultant force of the three drive wires 6 on the flexible joint 202 can be equivalent to a force along the axial direction of the flexible joint and a couple along a certain direction in space. Due to the axial incompressibility of the flexible joint 202, the force along the joint axis will not affect the movement of the flexible joint 202. Instead, the flexible joint 202 will bend within the plane of the equivalent resultant couple of the three drive wires 6. By controlling the movement of the three drive wires 6 according to a certain motion law, the flexible joint 202 can achieve bending movement in any plane. Through this bending movement, combined with the fact that the gripper is in a retracted state with a small external size, the gripper can pass through the narrow and curved natural cavity environment of the human body. It can also actively guide the movement of the flexible joint 202 through the drive wires 202 at the bifurcation of the cavity, thus enabling it to reach the target working position through the narrow and tortuous environment.

[0051] Once the gripper reaches the target position, the three drive wires are first released. Under the self-restoring force of the flexible joint 202, the gripper will return to its original position. Figure 8 The initial configuration is shown. At this point, due to the change in the task, the gripper needs to switch from the aforementioned bending motion to the extending and retracting motion to capture the target object. At this time, the following is employed... Figure 13 The spread-and-fold control strategy shown in the diagram implements the spread-and-fold movement of the folding and grasping section, as detailed below:

[0052] The three drive wires 6 are synchronously driven to move. At this point, the movement of the three drive wires 6 is synchronized, and the resultant force of the three drive wires 6 on the flexible joint 202 is a pure force along the axial direction of the flexible joint 202 without any torque. Due to the incompressibility of the flexible joint 202 along its axial direction, this force will not cause the flexible joint 202 to move. Then, the force of the three drive wires 6 is increased synchronously, ensuring that the forces of the three drive wires 6 remain equal, i.e., their resultant force is always a pure force acting on the central axis of the flexible joint 202. As the driving force gradually increases, the force of the drive wires 6 on the folding and grasping part will overcome the resistance of the return torsion springs located inside the joints of the folding and grasping part, causing the folding and grasping part to gradually unfold under the synchronous action of the three drive wires 6, as shown below. Figure 10 As shown.

[0053] When the folding and gripping mechanism unfolds to a size sufficient to capture the target object, since the target object's location in the working environment is unknown, the gripper needs to be able to adjust its own orientation to achieve the gripping operation. For example... Figure 11 As shown, the control strategy switches from deployment to directional control, meaning the three drive wires 6 are driven again with different forces. Due to the resistance of the return torsion spring in the folding and gripping section, the length of the drive wires 6 in the folding and gripping section remains unchanged, meaning the overall dimensions of the folding and gripping section remain unchanged. However, since the forces of the three drive wires 6 are no longer equal, their resultant force on the flexible joint 202 will include an additional couple in addition to the axial force. The flexible joint 202 will then bend within the plane of this couple. The motion of the flexible joint 202 at this time is similar to... Figure 9 The motion shown is similar; that is, the grasper will bend on any plane in three-dimensional space while maintaining a large unfolded external size, and eventually find the target object's location and capture it, as shown in the example. Figure 11 As shown.

[0054] When the target object successfully enters the folding and gripping section, the control strategy is switched again from the direction control strategy to the unfolding and retraction control strategy, that is, all three drive wires 6 are simultaneously released. Because the three drive wires 6 are released simultaneously, under the restoring force of the return torsion spring in the folding and gripping section, the size of the folding and gripping section will gradually shrink. Since the target object has now entered the gripper, as the folding and gripping mechanism gradually shrinks under the force of the return torsion spring, the target object will be tightly locked inside the gripper, as shown below. Figure 12 As shown. At this point, the target object can be removed from the body by retrieving the push tube connected to the capture device via 704.

Claims

1. A wire-driven multi-mode folding and unfolding gripper with flexible joints, characterized in that: Includes the unfolding and grasping part, flexible joint assembly and drive wire; The folding and gripping part includes three circumferentially distributed scissor units, which are cross-hinged by two connecting rods in an X shape, and a return torsion spring is installed at the hinge position; in adjacent scissor units, the top and bottom ends are respectively connected to the second connecting component through a first connecting component; the first connecting component and the second connecting component are connected to the scissor unit through two joints with coplanar axes to form a rotating pair; The flexible joint assembly has an upper connecting platform at the top, which is connected to three second connecting components through three circumferential connecting rods to form a rotating pair, and a reset torsion spring is installed at the connection position; the flexible joint assembly has a lower connecting platform at the bottom, and a connector is designed on the bottom surface of the lower connecting platform to connect to the push guide tube; a flexible joint is designed between the upper connecting platform and the lower connecting platform. The drive wire consists of three wires, with their output ends fixed to three first connecting components. They are then guided downwards through the guide holes on the first connecting components and the guide holes in the second connecting components, and finally pass through the bottom connector of the flexible joint component and enter the push guide tube. They are then connected to their respective drivers inside the push guide tube.

2. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 1, characterized in that: The connecting rods in the scissor lift unit are arc-shaped rods with their outer arc surfaces facing in the same direction and toward the outside of the unfolded gripping part.

3. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 1, characterized in that: The included angle between the motion planes of adjacent scissor lift units is 60°; at the same time, the included angle between the rotational axes of the two joints in the first connecting assembly and the second connecting assembly is 120°.

4. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 1, characterized in that: The guide hole axes in the first and second connecting components are perpendicular to the plane containing the axes of the two connectors, and intersect at the angle bisector of the angle between the axes of the two connectors.

5. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 1, characterized in that: The connection between the flexible joint assembly and the folding and gripping part is as follows: the bottom ends of the three connecting rods are connected to three vertical planes that are equally spaced around the upper connecting platform to form a rotating pair; the top ends of the three connecting rods are respectively connected to the joints designed on the three second connecting components to form a rotating pair, and the axes of the rotating pairs are perpendicular to the three vertical planes around the upper connecting platform.

6. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 1, characterized in that: After passing through the guide hole in the second connecting assembly, the drive wire also passes through the guide holes designed around the upper connecting platform, the lower connecting platform, and the connector head in sequence to enter the push guide tube.

7. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 1, characterized in that: In the initial state, the three drive wires are in a relaxed state. Under the restoring force of each reset torsion spring, the unfolding and grasping part is in a retracted state, and the flexible joint is in an unbent state.

8. A wire-driven multi-mode folding and unfolding gripper with flexible joints as described in any one of claims 1 to 7, characterized in that: The motion control strategy is as follows: Directional control: The actuator drives three drive wires, making the force of the drive wires less than the resistance of the return torsion spring in the unfolding and grasping part, but greater than the force required for the flexible joint to bend, thus causing the flexible joint to bend; by controlling the three drive wires, the flexible joint can achieve bending motion of the unfolding and grasping part in any plane. Extension and retraction control: The three drive wires are driven synchronously, so that the force exerted by the drive wires on the folding and grasping part is greater than the resistance of the return torsion spring. The folding and grasping part gradually unfolds under the synchronous action of the three drive wires; furthermore, the three drive wires are driven with different forces, causing the flexible joint to bend.

9. The wire-driven multi-mode folding and unfolding gripper with flexible joints as described in claim 8, characterized in that: Directional control enables navigation through narrow and curved pipes; upon reaching the target location, it switches to deployment and retraction control to capture the target object; after capture, deployment and retraction control switches back to directional control to retrieve the target object.

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