End effector for robotic arm

Abstract

The invention discloses an end effector for a mechanical arm. The end effector comprises a) a first shell, a second shell and a third shell, wherein the first shell is provided with a center line; b) at least one rotating member, the axis of rotation of which is perpendicular to the centerline; c) a set of first pairs of drive lines (112); the first pair of driving wires (112) is connected to the at least one rotating component and is driven to rotate by a counter-pulling mechanism, and the tension and displacement of each driving wire in the first pair of driving wires (112) are the same but opposite in direction.

Description

Technical Field

[0001] The present invention generally relates to an end effector for a robotic arm, and more particularly to a non-backdrivable cable-driven gripper. Background Art

[0002] Gastric cancer and colorectal cancer are common cancer types in different regions of the world. These cancers are also one of the main causes of cancer death. Gastrointestinal (GI) cancers originate from the mucosal layer. If cancer lesions are removed in the pre-cancerous or early stage to prevent their spread to lymph nodes, the survival rate of patients may be increased.

[0003] Endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) are methods for removing pre-cancerous lesions and early cancers in the gastrointestinal tract. These procedures are performed using a flexible endoscope and have the advantages of minimally invasive and organ-preserving.

[0004] Postoperative closure of ESD or EMR requires precise suturing to avoid perforation and bleeding. In open surgery, a classic suturing method is to use a long straight clamping instrument to manipulate the suture needle. The clamping instrument has a lobster-claw-shaped gripper and multiple rotating joints driven by a drive wire such as shape memory alloy (SMA). When the suture needle penetrates human tissue, the gripper rotates its wrist to make the suture needle move along a circular trajectory. The mechanical movement can be easily transmitted through the transmission shaft of the controller. This intuitive design reduces the learning curve for surgeons.

[0005] However, developing a reliable endoscopic suturing device has always been a challenge for engineers because its size and strength requirements are extremely critical. Generally speaking, the main difficulties of endoscopic suturing robots are as follows: First, the robotic arm must be small and flexible enough to reach the target position without harming the patient. Second, since current flexible endoscopes usually have only one or two instrument channels, the complexity and quantity of the drive components of the suturing mechanism are limited. Third, the robot must be able to stably manipulate the suture needle to ensure that its position and direction do not shift. Fourth, rotation along the endoscope axis is technically difficult because it is challenging to transmit the rotational movement outside the patient's body to the clamping device. Summary of the Invention

[0006] The present invention provides an end effector for a robotic arm. In one embodiment, the end effector includes: a) a first housing having a center line; b) at least one rotating member, the rotation axis of the rotating member being perpendicular to the center line; c) a first pair of drive wires; the first pair of drive wires are connected to the at least one rotating member, driven to rotate by an opposed-pull mechanism, and the tension and displacement of each drive wire in the first pair of drive wires are the same but in opposite directions. Brief Description of the Drawings

[0007] Figure 1 Shows a schematic internal structure diagram of an end effector embodiment of the present invention.

[0008] Figure 2 Show Figure 1 Exploded schematic diagram of the illustrated embodiment.

[0009] Figure 3 Show Figure 1 Schematic diagram of the interlocking mechanism between the spherical worm gear and the jaw in the illustrated embodiment.

[0010] Figure 4 Show Figure 1 Schematic diagram of the driving bevel gear in the illustrated embodiment. Detailed implementation manner

[0011] The present invention describes a structure and method of a non-backdrivable cable-driven jaw that can be used as an end effector of a robotic system. The basic application of the jaw is to provide a clinical solution for endoscopic suturing. The non-backdrivable jaw can exert an extremely high clamping force on the suture needle; and its rotating joint can provide rotational movement to penetrate human tissue, and these two structures can be embedded in a very small space. These two structures are driven by a pair of cables, enabling the jaw to be mounted on any cable-driven robotic arm. The jaw also has the advantage of scalability, and thus can be applied to a variety of applications, not limited to endoscopic surgery.

[0012] In one embodiment, the present invention provides a non-backdrivable cable-driven jaw, which is a device dedicated to endoscopic suturing surgery. The device has two degrees of freedom (DOF), including a jaw and a rotating joint along the axis of the body, and can be connected to a flexible robotic arm. The optimized design of this distal device requires the use of a coated wire driver to improve the driving efficiency and control accuracy. In one embodiment, the present invention generally relates to endoscopic robots, and particularly relates to the suturing application of flexible robotic arms in endoscopic surgery.

[0013] The present invention provides a jaw structure for a robotic system. In one embodiment, the structure includes: a first member as a rotating part, including a housing with two mirror-shaped bevel gears installed inside, the rotation axis of the first member being perpendicular to the center line of the housing; the two bevel gears are connected to another central bevel gear, the rotation axis of the other central bevel gear coinciding with the center line of the housing; a second member as a jaw part, including a housing connected to the ends of the bevel gears in the first member to synchronize the rotational movement; a spherical worm gear is vertically installed on the center line of the housing such that the pinion on the jaw is connected to the spherical worm gear, forming a spherical spiral motion for driving the jaw to open and close.

[0014] In one embodiment, the two bevel gears are respectively connected to one of a pair of drive lines, and the pair of drive lines is configured with a pulling mechanism, so they are driven in opposite directions and have the same displacement.

[0015] In one embodiment, the two bevel gears rotate in opposite directions by pulling the corresponding drive lines.

[0016] In one embodiment, the central bevel gear rotates according to the rotation direction of the bevel gears driven by the pair of drive lines.

[0017] In one embodiment, the central bevel gear is driven to rotate by a pair of drive lines configured with a pulling mechanism.

[0018] In one embodiment, a wiring groove is provided below the tooth surface of the bevel gear for fixing the ends of the drive lines.

[0019] In one embodiment, the housing consists of two parts and is connected by metal pins.

[0020] In one embodiment, the central bevel gear is supported by a circular bearing and can rotate freely, and the bearing is located in the second member.

[0021] In one embodiment, the housing of the jaw part is connected to the central bevel gear in the first member by metal pins.

[0022] In one embodiment, the second member rotates synchronously with the central bevel gear in the first member.

[0023] In one embodiment, the jaw part rotates around the center of the housing by driving a pair of drive lines in the first member.

[0024] In one embodiment, the jaw part has another pair of drive lines that pass through the hole in the center of the first member.

[0025] In one embodiment, the other pair of drive lines is connected to opposite sides of the spherical worm gear.

[0026] In one embodiment, two of the jaws are perpendicularly connected to the center line of the housing.

[0027] In one embodiment, a pinion gear is attached to the articulating edge of each of the two jaws and is connected to the tooth surface of the spherical worm gear.

[0028] In one embodiment, the rotational direction of the jaws is opposite to the rotational direction of the spherical worm gear.

[0029] In one embodiment, the jaws are driven by a pair of drive lines passing through the central hole of the central bevel gear of the first member and are independent of the rotational movement of the first member.

[0030] In one embodiment, the jaw gears meshing with the spherical worm gear are vertically offset relative to the center line.

[0031] In one embodiment, the spherical worm gear has two sets of tongues and grooves with opposite directions.

[0032] In one embodiment, four drive lines from the flexible robotic arm are fixed at the opening of the circular housing.

[0033] The present invention provides an end effector for a robotic arm. In one embodiment, the end effector includes: a) a first housing having a center line; b) at least one rotating member, the rotation axis of the rotating member being perpendicular to the center line; c) a first pair of drive lines; the first pair of drive lines is connected to the at least one rotating member, driven to rotate by an anti-pulling mechanism, and the tension and displacement of each drive line in the first pair of drive lines are the same but in opposite directions.

[0034] In one embodiment, the at least one rotating member includes two bevel gears 104, 105, each of the two bevel gears is connected to one of the drive lines in the first pair of drive lines 112 to form the anti-pulling mechanism, and the two bevel gears are connected to a central bevel gear 106 whose rotation axis is along the center line.

[0035] In one embodiment, the at least one rotating member includes a spherical worm gear 103 having two ends, and each of the two ends is connected to one of the drive lines in the first pair of drive lines 112 to form the anti-pulling mechanism.

[0036] In one embodiment, the spherical worm gear 103 includes an hourglass-shaped surface having two sets of tongues and grooves, which are interlocked with the meshing components on the jaws 101, 102.

[0037] In one embodiment, the central bevel gear 106 is connected to an end member to drive the rotation of the end member.

[0038] In one embodiment, the end member includes a second housing and a second pair of drive lines. The second housing contains a globoidal worm gear 103 having two ends, and the two ends are respectively connected to one drive line of the second pair of drive lines 113 to form the tension mechanism.

[0039] In one embodiment, the globoidal worm gear 103 includes an hourglass-shaped surface that interlocks with the meshing components on two jaws 101, 102 to drive the clamping angle of the two jaws.

[0040] In one embodiment, the first housing includes a tongue that is inserted into a groove on the second housing as a limiting member.

[0041] In one embodiment, the two bevel gears include a tooth surface and a wiring groove that is located below the tooth surface.

[0042] In one embodiment, the jaws are connected to the end effector by one or more metal pins.

[0043] In one embodiment, the meshing component includes a pinion gear.

[0044] In one embodiment, the hourglass-shaped surface includes two sets of tongues and grooves, and the directions of each set of tongues and grooves are opposite.

[0045] In one embodiment, the two jaws include gear teeth that are vertically offset relative to the center line.

[0046] In one embodiment, the applied force can be increased by controlling the rotational reduction ratio on the hourglass-shaped surface that interlocks with the meshing component.

[0047] In one embodiment, the second pair of drive lines passes through a hole in the center of the central bevel gear 106.

[0048] The present invention provides a non-backdrivable cable-driven jaw 100. In an embodiment of the present invention, the instrument is a flexible robotic suturing device for endoscopic surgery. The suturing device includes a clamping portion 114 and a rotating portion 115.

[0049] In an embodiment of the present invention, the two pairs of drive lines 112, 113 are led out from the instrument channel of the flexible robotic arm in a tension mechanism configuration, so that the entire structure can be reduced. The flexibility of the drive lines enables them to bend without applying significant forces to the structure.

[0050] The clamping part 114 includes a spherical worm gear 103 with mirror threads and two jaws 101, 102 with gear teeth. Driving the spherical worm gear 103 can control the clamping angles of the two jaws 101, 102. These components are covered by a circular housing 108, 109.

[0051] The rotating part 115 includes two small driving bevel gears 104, 105 and a central bevel gear 106, and the central bevel gear 106 is connected to the housing 108, 109 of the clamping part. Driving one of the small bevel gears 104, 105 will drive the central bevel gear 106 and the other small bevel gear 104, 105 to rotate. These components are covered by another circular housing 110, 111.

[0052] The end effector on the robotic instrument can be a jaw 101, 102 in any form, such as having a serrated surface or features suitable for a specific suture needle.

[0053] The present invention details the structure of the non-backdrivable cable-driven jaw 100 and the mechanisms for separately driving the clamping part 114 and the rotating part 115.

[0054] In the rotating part 115, the rotational movement is controlled by a pair of drive lines 112. One drive line is connected to a small bevel gear 105, and the other drive line is connected to the other small bevel gear 104. The pair of drive lines 112 is configured with a pulling-against mechanism such that the tension directions of the drive lines are the same, and the displacement amounts of each drive line are the same but in opposite directions. This mechanism enables the central bevel gear 106 to be perpendicularly connected to the two small bevel gears 104, 105 and to rotate along the central axis of the jaw through the pair of drive lines 112. The support bearing 107 ensures the stable rotation of the central bevel gear 106 within the rotating part 115 and the housing 110, 111.

[0055] In the clamping portion 114, the other pair of drive wires 113 is used to control the movement of the jaws 101, 102. The other pair of drive wires 113 passes through small holes on the axis of the central bevel gear 106 and is respectively connected to opposite sides of the globoidal worm gear 103. Through the same pulling mechanism acting on the drive wires 113, the globoidal worm gear 103 rotates along its own axis and is supported by the housings 108, 109 of the clamping portion. Two sets of tongues and grooves are provided on the hourglass-shaped surface of the globoidal worm gear 103, which can drive the two jaws to manipulate human tissue or tools during the suturing operation. The specific geometric structure of the globoidal worm gear is a spherical spiral form, which keeps the rotation centers of the driving body and the driven body in the same position while maintaining full contact of the entire tooth surface. This design is crucial for reducing the size of components and supporting microfabrication. The surfaces of the tongues and grooves are interlocked with the individual gears of the meshing components on the jaws 101, 102. The two spiral structures rotate relative to each other, causing the two jaws to simultaneously increase or decrease the clamping angle. The clamping portion changes the jaw position only when an input force is received, and the spiral force of the tongues and grooves ensures that the jaws are locked in a specific position. The spiral structure can also amplify the clamping force by controlling the rotational reduction ratio. This amplified clamping force can firmly hold any suture needle. The gear teeth on the jaws 101, 102 are not placed in the center but are designed with an offset up and down to adapt to the new groove profile. This design can prevent interference, simplify the geometry, and enhance the strength of the model. Various surface features can be integrated on the jaw surfaces to better fix the suture instrument or human tissue.

[0056] The rotating part 115 is installed within the bottom rotating part housing 110 and the top rotating part housing 111. The clamping part 114 is installed within the bottom clamping part housing 108 and the top clamping part housing 109. Four mounting holes for fixing metal pins are provided on the rotating part housings 110, 111, while three mounting holes for fixing metal pins are provided on the clamping part housings 108, 109. The central bevel gear 106 is connected to the bottom clamping part housing 108 and the top clamping part housing 109 through two holes for fixing its end with pins. At the front end of the bottom rotating part housing 110, there is a small tongue that can slide within the grooves on the clamping part housings 108, 109 and serves as a limiter. The width of the tongue is 90 degrees, while the width of the groove is 270 degrees, enabling a maximum rotation range of 180 degrees. Additionally, the clamping range of the jaws is also limited by the clamping part housings 108 and 109. To optimize the smoothness of wiring and simplify the manufacturing process, two wiring holes on the bottom clamping part housing 109 point towards the center line of the entire assembly. Since the other pair of drive lines 113 is not directly connected to the jaws 101, 102, only one metal pin needs to be removed for extraction. The advantage of this design is that different types of jaws can be adapted to the same robotic arm, thus saving costs and effort. During the assembly process, all movable components can be pre-installed into the bottom rotating part housing 110 and the bottom clamping part housing 108, and then encapsulated using the top rotating part housing 111 and the top clamping part housing 109. Four outermost holes for fixing the four drive lines of the flexible robotic arm are provided on the back of the rotating part housings 110, 111.

[0057] In the structure of the small bevel gears 104, 105, a wiring groove is provided below the tooth surface of the small bevel gears. The small curvature of the wiring groove can be optimally utilized when the drive line is soft and tough. A straight hole is opened at the end of the wiring groove to connect to a larger opening. A hollow metal piece with a drive line passed through it is tightly pressed into the opening, and the hollow metal piece helps to fix the drive line at the opening.

Claims

1. An end effector for a robotic arm, comprising: a. A first housing having a center line; b. At least one rotating member, the axis of rotation of the rotating member being perpendicular to the center line; c. A set of first pairs of drive lines; Characterized in that: the first pairs of drive lines are connected to the at least one rotating member, driven to rotate by a pulling mechanism, and the tension and displacement of each drive line in the first pairs of drive lines are the same but in opposite directions.

2. The end effector according to claim 1, characterized in that: The at least one rotating member includes two bevel gears (104, 105), and the two bevel gears are respectively connected to one drive line in the first pairs of drive lines (112) to form the pulling mechanism, and the two bevel gears are connected to a central bevel gear (106) with a rotation axis along the center line.

3. The end effector according to claim 1, characterized in that: The at least one rotating member includes a spherical worm gear (103) having two ends, and the two ends are respectively connected to one drive line in the first pairs of drive lines (112) to form the pulling mechanism.

4. The end effector according to claim 3, characterized in that: The spherical worm gear (103) includes an hourglass-shaped surface having two sets of tongues and grooves, which are interlocked with the meshing members on the jaws (101, 102).

5. The end effector according to claim 2, wherein: The central bevel gear (106) is connected to an end member to drive the end member to rotate.

6. The end effector according to claim 5, characterized in that: The end member includes a second housing and a set of second pairs of drive lines, the second housing contains a spherical worm gear (103) having two ends, and the two ends are respectively connected to one drive line in the second pairs of drive lines (113) to form the pulling mechanism.

7. The end effector according to claim 6, wherein: The spherical worm gear (103) includes an hourglass-shaped surface, which is interlocked with the meshing members on the two jaws (101, 102) to drive the clamping angle of the two jaws.

8. The end effector according to claim 6, characterized in that: The first housing includes a tongue, and the tongue is inserted into the groove on the second housing as a limiting member.

9. The end effector according to claim 2, characterized in that: The two bevel gears include a tooth surface and a wiring groove, and the wiring groove is located below the tooth surface.

10. The end effector according to claim 4 or 7, characterized in that: The jaws are connected to the end effector by one or more metal pins.

11. The end effector according to claim 4 or 7, characterized in that: The meshing member includes a pinion.

12. The end effector according to claim 4 or 7, characterized in that: The hourglass-shaped surface includes two sets of tongues and grooves, and the directions of each set of tongues and grooves are opposite.

13. The end effector according to claim 4 or 7, characterized in that: The two jaws include gear teeth that are vertically offset relative to the center line.

14. The end effector according to claim 4 or 7, characterized in that: By controlling the rotational reduction ratio on the hourglass-shaped surface interlocked with the meshing member, the applied force can be increased.

15. The end effector according to claim 2, characterized in that: The second pairs of drive lines pass through a hole in the center of the central bevel gear (106).

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