Mechanism for controlling a four-cable wrist instrument

Abstract

This invention provides a mechanism for controlling a four-cable wrist device. In one embodiment, the mechanism includes: a) a base; b) a first drive cable, a second drive cable, a third drive cable, and a fourth drive cable, each drive cable having one end connected to the four-cable wrist device and the other end connected to the base; c) a first cam, a second cam, and a third cam, each cam being used to independently control one degree of freedom of the four-cable wrist device; each of the first, second, and third cams includes two cable adjustment surfaces, such that a specific pair of drive cables of the first, second, third, or fourth drive cable is placed on one of the two cable adjustment surfaces, and the other two drive cables are placed on the other cable adjustment surface.

Description

Technical Field

[0001] This invention relates to a mechanism for controlling a four-cable wrist device. Background Technology

[0002] Four-cable wrist instruments are commonly used in robot-assisted minimally invasive surgery. During surgery, these instruments are typically driven by a rear-end drive mechanism. Existing rear-end drive mechanisms usually employ cylindrical winches, linkages, rocker arms, or movable pulleys to control the four-cable wrist instrument by relaxing two cables and tightening the other two cables to the same length, thus achieving three degrees of freedom of movement. During pitch, yaw, or gripping movements, the relaxation and tightening lengths must always remain equal. However, the wrist structure design does not always ensure that the relaxation and tightening lengths are equal during pitch movements. Furthermore, existing rear-end drive mechanisms require at least three motors to control the three degrees of freedom of the four-cable wrist instrument. Each degree of freedom requires at least two motors coupled together. Therefore, such four-cable wrist instruments cannot be manually controlled. This invention proposes a cam-based rear-end drive mechanism. The three degrees of freedom of the four-cable wrist instrument can be completely decoupled, thereby enabling manual control of the four-cable wrist instrument. In addition, the shape of the cam can be optimized to meet the different needs of the changing relationship between the four cables in a four-cable wrist device, thereby improving its versatility. Summary of the Invention

[0003] This invention provides a mechanism for controlling a four-cable wrist device. In one embodiment, the mechanism includes: a) a base; b) a first drive cable, a second drive cable, a third drive cable, and a fourth drive cable, each drive cable having one end connected to the four-cable wrist device and the other end connected to the base; c) a first cam, a second cam, and a third cam, each cam being used to independently control one degree of freedom of the four-cable wrist device; each of the first, second, and third cams includes two cable adjustment surfaces, such that a specific pair of drive cables from the first, second, third, or fourth drive cables is positioned between the two cable adjustment surfaces. On one of the cable adjustment surfaces, two other drive cables are placed on the other cable adjustment surface; when the first cam is driven to rotate, the first and third drive cables can be simultaneously relaxed or tightened, while the second and fourth drive cables are correspondingly tightened or relaxed simultaneously; when the second cam is driven to rotate, the first and second drive cables can be simultaneously relaxed or tightened, while the third and fourth drive cables are correspondingly tightened or relaxed simultaneously; and when the third cam is driven to rotate, the second and third drive cables can be simultaneously relaxed or tightened, while the first and fourth drive cables are correspondingly tightened or relaxed simultaneously. Attached Figure Description

[0004] Figure 1A This invention demonstrates a four-cable wrist device used in one embodiment of the invention.

[0005] Figure 1B exhibit Figure 1A The four-cable wrist instrument shown has 6 clamps.

[0006] Figure 1C exhibit Figure 1A The structure shown is the four-cable wrist device assembled with four device drive cables.

[0007] Figure 1D The demonstration shows four instrument drive cables that need to be loosened or tightened to achieve pitch, yaw, or clamping movements.

[0008] Figure 2 An equation for determining the shape of a cam is shown in one embodiment of the present invention.

[0009] Figure 3A An embodiment of the present invention is shown for controlling a four-cable wrist device.

[0010] Figure 3B exhibit Figure 3A The base of the mechanism shown.

[0011] Figure 3C exhibit Figure 3A Further details of the mechanism shown. Detailed Implementation

[0012] The rear-end drive mechanism used in minimally invasive surgery can drive a four-cable wrist instrument via four cables to achieve pitch, yaw, and clamping movements. Existing rear-end drive mechanisms typically use cylindrical winches, connecting rods, rocker arms, or movable pulleys to control the four-cable wrist instrument, but these methods require coupled control of the instrument. This invention provides a cam-based rear-end drive mechanism using three cams, achieving complete decoupled control of the three degrees of freedom of the four-cable wrist instrument. This cam-based rear-end drive mechanism allows for manual operation and is more versatile.

[0013] This invention proposes a cam-based rear-end transmission mechanism that uses cams to control a four-cable wrist device. The invention also proposes a cam shape optimization method. Furthermore, this invention designs a sequential assembly method for the cam-based rear-end transmission mechanism and a driving method for the four-cable wrist device. The cam-based rear-end transmission mechanism employs three cams, each of which independently controls one of the three degrees of freedom (deflection, pitch, and clamping) of the four-cable wrist device, thereby achieving completely decoupled control.

[0014] The cam-based rear-end drive mechanism can control the three degrees of freedom of the four-cable wrist device in a completely decoupled manner. This complete decoupling design enables manual control of the four-cable wrist device. Furthermore, depending on the different structures of the four-cable wrist device, there are specific correspondences between the length changes of the four cables. Optimization of the cam shape allows the cam-based rear-end drive mechanism to satisfy these correspondences, thereby adapting to more types of four-cable wrist devices.

[0015] In one embodiment, the rear-end transmission mechanism of the present invention includes three cams for controlling, such as Figures 1A to 1D The four-cable wrist device is shown. In another embodiment, each of the three cams has a [specific feature / feature] according to [the specific requirements]. Figure 2 The cam shape is optimized based on the equations and models shown to achieve the movement of the four-cable wrist device.

[0016] The present invention will use a cam-based rear-end transmission mechanism 300 as an example to illustrate its technical details. For example... Figure 3A As shown, the cam-based rear-end transmission mechanism 300 can be driven by a medical robot or a handheld device to control the four-cable wrist device to perform pitch, yaw, and clamping movements. The cam-based rear-end transmission mechanism 300 includes:

[0017] The base 310 of the cam-based rear transmission mechanism 300 is as follows: Figure 3B As shown. The base 310 is an integrated structural component and can be made of photopolymer 3D printing resin. The base 310 can be detachably installed in a medical robot or handheld device. All components are mounted on the base 310. The four drive cables are wound between the components and fixed to the columns 371 or 372 of the base 310.

[0018] Cam 351 provides a solid surface for adjusting the lengths of two specific pairs of drive cables; cam 352 provides a solid surface for adjusting the lengths of two specific pairs of drive cables; cam 353 provides a solid surface for adjusting the lengths of two specific pairs of drive cables. Drive connector 354 is used to connect cam 351 and the drive device below it; drive connector 355 is used to connect cam 352 and the drive device below it; drive connector 356 is used to connect cam 353 and the drive device below it. The drive device includes a motor, a handheld device, etc.

[0019] The drive cable 301 for controlling the four-cable wrist device is connected to the three cams and then fixed to the column 371 of the base 310; the drive cable 302 for controlling the four-cable wrist device is connected to the three cams and then fixed to the column 372 of the base 310; the drive cable 303 for controlling the four-cable wrist device is connected to the three cams and then fixed to the column 372 of the base 310; the drive cable 304 for controlling the four-cable wrist device is connected to the three cams and then fixed to the column 371 of the base 310.

[0020] Guide pulley 311 is used to guide drive cable 301 and change its direction; guide pulley 312 is used to guide drive cable 302 and change its direction; guide pulley 313 is used to guide drive cable 303 and change its direction; guide pulley 314 is used to guide drive cable 304 and change its direction. Guide pulleys 321 to 327 and guide pulleys 331 to 337 are used to change the direction of the cable and cooperate with each cam to quantitatively tighten and loosen the cable. The centers of guide pulleys 322 to 325 form a rectangle symmetrical about the rotation axis of cam 351. The centers of guide pulleys 324 to 327 form a rectangle symmetrical about the rotation axis of cam 352. The centers of guide pulley 326, the center of guide pulley 327, and the two tangent points between the drive cable and the column of base 310 form a rectangle symmetrical about the rotation axis of cam 353.

[0021] Bearings 361 to 366 are used to fix drive connectors 354 to 356 and to assemble the drive connectors together with the base 310.

[0022] Each of the three cams is used to independently control one degree of freedom (pitch, yaw, or grip) of the four-cable wrist device. When the length changes of the four drive cables of the four-cable wrist device are equal and the two pairs of cables change in opposite directions, the winding order of the four drive cables on the surfaces of the three cams is different, but the shape optimization method of each cam is the same. Since the motion of the three cams is completely decoupled, the shape of each cam can be optimized independently. The cam shape optimization method of the cam-based rear transmission mechanism 300 is described below.

[0023] set up Indicates the length of the drive cable as a function of the cam. ( =351,352,353) Rotation angle A changing function. Let... Indicates cam The shape curve in the polar coordinate system has a polar radius that varies with the polar angle. A changing function. Let... and The polar angle is the point of contact between the drive cable and the cam. The cam shape optimization method is determined based on the following calculation formula:

[0024]

[0025] (1)

[0026] In the above formula, such as Figure 2 As shown, for (From point) (the perpendicular line to the cam's rotation axis) and (guide pulley) The angle between the axes of symmetry (which are paired and distributed); It is one of the two intersection points between the line connecting the centers of the two nearest guide pulleys and the outline of the guide pulley; The distance between the axes of the two furthest guide pulleys is half the distance between them, and the relationship can be expressed as:

[0027] (2)

[0028] When the length changes of the four drive cables of a four-cable wrist instrument are equal and the two pairs of cables change in opposite directions, the winding order of the four drive cables on the three cam surfaces is different, but the shape optimization method of each cam is the same. During pitch, yaw, and clamping movements, the change in the rotation angle of the four-cable wrist instrument is directly proportional to the change in cable length, and this proportional relationship is the same during yaw and clamping movements.

[0029] It is about The proportional function can be expressed as: . This indicates the rate of change of the drive cable length when the cam angular velocity is constant; the cam angular velocity is manually set. To simplify the optimization process, it is usually set... .

[0030] like Figure 2 As shown, when the curve of the cam shape is changed from an ellipse half and ellipse When it is composed of half of the, and its first derivative The equations are given by formulas (3) and (4) respectively. (Linear line) Ellipse minor axis and ellipse The major axis of is of length . In addition, ellipse The length of the major axis is ,oval The length of the minor axis is .

[0031] (3)

[0032] (4)

[0033] At each point of tangency between the drive cable and the cam, the slope of the tangent line in the cam shape is equal to the slope of the corresponding drive cable. Polar angle. and They can be represented by the following equations respectively.

[0034] (5)

[0035] (6)

[0036] Ideally, when the cam is in its initial position, it should... It is symmetrical about the axis, such as Figure 2 As shown. When the rotation angle of the cam reaches... At this point, the length changes of the four drive cables on both sides reach their limits. The changes are equal but in opposite directions.

[0037] In practical applications, the optimization method described above is used to obtain... , , , The optimal solution for sum and , such that the maximum value is max{ Minimize. Therefore, the actual elliptic curve can basically achieve the effect of the drive cable length changing linearly with the cam rotation angle.

[0038] In this invention, a cam-based rear-end transmission mechanism 300 is connected to a four-cable wrist device via four drive cables. By rotating cams 351, 352, and 353 on the cam-based rear-end transmission mechanism 300, drive cables 1, 2, 3, and 4 can be tightened or loosened, thereby enabling the four-cable wrist device to work collaboratively with the cam-based rear-end transmission mechanism 300 to achieve pitch, yaw, and clamping movements of the four-cable wrist device. In this working mode, regardless of whether the changes in the length of the four drive cables are equal to the changes in the cam angle, the opening and closing angles of the four-cable wrist device can be designed to be proportional to the cam rotation angle during pitch, yaw, or clamping movements. Due to the completely decoupled design, the cam-based rear-end transmission mechanism 300 provides more intuitive control of the four-cable wrist device and allows for manual control without relying on a motor.

[0039] The components of the cam-based rear-end transmission mechanism 300 include cams, drive cables, guide pulleys, drive connectors, bearings, etc. The three degrees of freedom of the four-cable wrist device are independently controlled by driving three cams respectively. The three cams should be assembled on the same straight line, while their positional order can be arbitrarily set. Figures 3A to 3C As shown, the cam sequence assembly method of the cam-based rear-end transmission mechanism 300 is as follows.

[0040] The first drive module includes: cam 351, drive cable 301, drive cable 302, drive cable 303, drive cable 304, guide pulley 321, guide pulley 322, guide pulley 323, guide pulley 324, guide pulley 331, guide pulley 333, guide pulley 334 and guide pulley 335. Drive cable 301 connects to drive cable 1 of the four-cable wrist device, passing sequentially around guide pulley 323, cam 351, and guide pulley 325; drive cable 302 connects to drive cable 2 of the four-cable wrist device, passing sequentially around guide pulley 333, cam 351, and guide pulley 335; drive cable 303 connects to drive cable 3 of the four-cable wrist device, passing sequentially around guide pulley 321, guide pulley 322, cam 351, and guide pulley 324; drive cable 304 connects to drive cable 4 of the four-cable wrist device, passing sequentially around guide pulley 331, guide pulley 332, cam 351, and guide pulley 334. Drive cables 301 and 302 are located at the closest position on the same side of cam 351; drive cables 303 and 304 are located at the closest position on the other side of cam 351, opposite to drive cables 301 and 302.

[0041] The second drive module includes: cam 352, drive cable 301, drive cable 302, drive cable 303, drive cable 304, guide pulley 324, guide pulley 325, guide pulley 326, guide pulley 327, guide pulley 334, guide pulley 335, guide pulley 336, and guide pulley 337. Drive cable 301 sequentially passes over guide pulley 325, cam 352, and guide pulley 327; drive cable 302 sequentially passes over guide pulley 335, cam 352, and guide pulley 326; drive cable 303 sequentially passes over guide pulley 324, cam 352, and guide pulley 336; and drive cable 304 sequentially passes over guide pulley 334, cam 352, and guide pulley 337. Drive cables 301 and 303 are located at the closest positions on the same side of cam 352; drive cables 302 and 304 are located at the closest positions on the other side of cam 352, opposite to drive cables 301 and 303.

[0042] The third drive module includes: a cam 353, a base 310, drive cables 301, 302, 303, and 304, guide pulleys 326, 327, 336, and 337. Drive cable 301 sequentially passes over guide pulley 327 and cam 353, and is fixed to the base 310 of the cam-based rear-end transmission mechanism 300; drive cable 302 sequentially passes over guide pulley 326 and cam 353, and is fixed to the base 310 of the cam-based rear-end transmission mechanism 300; drive cable 303 sequentially passes over guide pulley 336 and cam 353, and is fixed to the base 310 of the cam-based rear-end transmission mechanism 300; drive cable 304 sequentially passes over guide pulley 337 and cam 353, and is fixed to the base 310 of the cam-based rear-end transmission mechanism 300. Drive cables 301 and 304 are located at the closest positions on the same side of cam 353; drive cables 302 and 303 are located at the closest positions on the other side of cam 353, opposite to drive cables 301 and 304.

[0043] This invention controls four drive cables by driving individual cams in a cam-based rear-end transmission mechanism 300, with each cam independently controlling one of the three degrees of freedom. This invention controls a four-cable wrist device by driving the four drive cables of the cam-based rear-end transmission mechanism 300, such as... Figure 1C As shown. Its control method is as follows.

[0044] The drive cables 1 and 3 of the four-cable wrist instrument are connected to the front guide channel of the drive cable of the jaw 5; drive cables 2 and 4 are connected to the front guide channel of the drive cable of the jaw 6. Drive cables 1 and 2 pass through the front guide channel and bypass the rear guide channel 7 from the same side. Drive cables 3 and 4 pass through the front guide channel and bypass the opposite side of the rear guide channel 7. Figure 1C As shown, drive cables 1 and 2 bypass the rear guide channel 7 and then bypass the opposite side of pin 11 to connect to the cam-based rear drive mechanism 300. Similarly, drive cables 3 and 4 bypass the rear guide channel 7 and then bypass the opposite side of pin 11 to connect to the cam-based rear drive mechanism 300.

[0045] Cable 1 of the four-cable wrist device is connected to drive cable 301; cable 2 of the four-cable wrist device is connected to drive cable 302; cable 3 of the four-cable wrist device is connected to drive cable 303; and cable 4 of the four-cable wrist device is connected to drive cable 304.

[0046] The cam-based rear-end drive mechanism 300 controls each degree of freedom of the four-cable wrist instrument in the same manner. A driveable cam 351 rotates about a first central axis, thereby controlling the synchronous deflection of the two jaws. A driveable cam 352 rotates about a second central axis, thereby controlling the synchronous pitch of the two jaws. A driveable cam 353 rotates about a third central axis, thereby controlling the synchronous clamping of the two jaws. The first, second, and third central axes are parallel to each other.

[0047] This invention provides a cam-based rear-end drive mechanism. In one embodiment, the cam-based rear-end drive mechanism includes: a base; four drive cables for connecting a four-cable wrist device; three cams, each providing a solid surface for adjusting the lengths of two specific pairs of drive cables; three drive connectors, each for connecting one of the three cams and a drive mechanism below it; a first group of four pulleys arranged along a rotation axis. The four pulleys are used to guide the drive cables and change their direction; a second group of fourteen pulleys arranged in four layers, each layer for one of the four drive cables. The second group of pulleys cooperates with the three cams to quantitatively tighten and loosen the drive cables; and three pairs of bearings for fixing and assembling the drive connectors to the base.

[0048] In one embodiment, the base of the cam-based rear-end drive mechanism includes two columns, to which the drive cable is fixed.

[0049] The present invention also provides a method for optimizing the cam shape of three cams in the mechanism. In one embodiment, each of the three cams is used to independently control one degree of freedom (pitch, yaw, or clamping) of a four-cable wrist device. Because the motions of the three cams are completely decoupled, the shape of each cam can be optimized independently. Indicates the length of the drive cable as a function of the cam. ( =351,352,353) Rotation angle A changing function. Let... Indicates cam The shape curve in the polar coordinate system has a polar radius that varies with the polar angle. A changing function. Let... and The polar angle is the point of contact between the drive cable and the cam. The cam shape optimization method is determined according to formula (1).

[0050] In the formula (1), as Figure 2 As shown, for (From point) (the perpendicular line to the cam's rotation axis) and (guide pulley) The angle between the axes of symmetry (which are paired and distributed); It is one of the two intersection points between the line connecting the centers of the two nearest guide pulleys and the outline of the guide pulley; It is half the distance between the axes of the two farthest guide pulleys, and the relationship is shown in formula (2).

[0051] In a further embodiment, when the length changes of the four drive cables of the four-cable wrist device are equal and the two pairs of cables change in opposite directions, the winding order of the four drive cables on the three cam surfaces is different, but the shape optimization method of each cam is the same. During pitch, yaw, and clamping movements, the change in the rotation angle of the four-cable wrist device is proportional to the change in cable length, and this proportional relationship is the same during yaw and clamping movements. It is about The proportional function can be expressed as: . This indicates the rate of change of the drive cable length when the cam angular velocity is constant; the cam angular velocity is manually set. To simplify the optimization process, it is usually set... .

[0052] In another embodiment, when the curve of the cam shape is composed of an ellipse... half and ellipse When it is composed of half of the line, the straight line Ellipse minor axis and ellipse The major axis of is of length . In addition, ellipse The length of the major axis is ,oval The length of the minor axis is . and its first derivative The formulas are given by formula (3) and formula (4) respectively.

[0053] In one embodiment, at each tangent point between the drive cable and the cam, the slope of the tangent line of the cam shape is equal to the slope of the corresponding drive cable. Polar angle and It can be represented by formula (5) and formula (6) respectively.

[0054] In one embodiment, when the cam is in the initial position, It is symmetrical about the axis, such as Figure 2 As shown. Ideally, when the cam's rotation angle reaches... At this point, the length changes of the four drive cables on both sides reach their limits. The changes are equal but in opposite directions. In practical applications, this is obtained through the optimization method described above. , , , The optimal solution for sum and , such that the maximum value is max{ Minimize. Therefore, the actual elliptic curve can basically achieve the effect of the drive cable length changing linearly with the cam rotation angle.

[0055] The present invention also provides a method for sequential assembly of cams. In one embodiment, the three degrees of freedom of a four-cable wrist device are independently controlled by driving three cams respectively. The assembly positions of the three cams should be on the same straight line. The positional order of the three cams can be arbitrarily set.

[0056] In one embodiment, the first drive module includes: a cam 351, drive cable 301, drive cable 302, drive cable 303, drive cable 304, guide pulley 321, guide pulley 322, guide pulley 323, guide pulley 324, guide pulley 331, guide pulley 333, guide pulley 334, and guide pulley 335. In another embodiment, the second drive module includes: a cam 352, drive cable 301, drive cable 302, drive cable 303, drive cable 304, guide pulley 324, guide pulley 325, guide pulley 326, guide pulley 327, guide pulley 334, guide pulley 335, guide pulley 336, and guide pulley 337. In another embodiment, the third drive module includes: cam 353, base 310, drive cable 301, drive cable 302, drive cable 303, drive cable 304, guide pulley 326, guide pulley 327, guide pulley 336 and guide pulley 337.

[0057] In one embodiment, the deflection of the four-cable wrist device can be achieved by any one of the three drive modules. The following description uses the first drive module as an example: Drive cable 301 is connected to drive cable 1 of the four-cable wrist device, passing sequentially around guide pulley 323, cam 351, and guide pulley 325; Drive cable 302 is connected to drive cable 2 of the four-cable wrist device, passing sequentially around guide pulley 333, cam 351, and guide pulley 335; Drive cable 303 is connected to drive cable 3 of the four-cable wrist device, passing sequentially around guide pulley 321, guide pulley 322, cam 351, and guide pulley 324; Drive cable 304 is connected to drive cable 4 of the four-cable wrist device, passing sequentially around guide pulley 331, guide pulley 332, cam 351, and guide pulley 334. Drive cables 301 and 302 are located at the closest positions on the same side of cam 351; drive cables 303 and 304 are located at the closest positions on the other side of cam 351, opposite to drive cables 301 and 302.

[0058] In one embodiment, the pitch of the four-cable wrist device can be achieved by any one of the three drive modules. The following description uses the second drive module as an example: Drive cable 301 sequentially passes over guide pulley 325, cam 352, and guide pulley 327; drive cable 302 sequentially passes over guide pulley 335, cam 352, and guide pulley 326; drive cable 303 sequentially passes over guide pulley 324, cam 352, and guide pulley 336; drive cable 304 sequentially passes over guide pulley 334, cam 352, and guide pulley 337. Drive cables 301 and 303 are located on the same side of cam 352; drive cables 302 and 304 are located on the other side of cam 352, opposite to drive cables 301 and 303.

[0059] In one embodiment, the clamping of the four-cable wrist device can be achieved through any one of the three drive modules. The following description uses the third drive module as an example:

[0060] Drive cable 301 passes sequentially around guide pulley 327 and cam 353, and is fixed to the base 310 of the cam-based rear transmission mechanism 300; drive cable 302 passes sequentially around guide pulley 326 and cam 353, and is fixed to the base 310 of the cam-based rear transmission mechanism 300; drive cable 303 passes sequentially around guide pulley 336 and cam 353, and is fixed to the base 310 of the cam-based rear transmission mechanism 300; drive cable 304 passes sequentially around guide pulley 337 and cam 353, and is fixed to the base 310 of the cam-based rear transmission mechanism 300. Drive cables 301 and 304 are located at the closest position on the same side of cam 353; drive cables 302 and 303 are located at the closest position on the other side of cam 353, opposite to drive cables 301 and 304.

[0061] The present invention also provides a medical device comprising a cam-based rear-end drive mechanism as described in the present invention.

[0062] The present invention also provides a surgical robot, which includes the medical device as described in the present invention.

[0063] This invention provides a mechanism for controlling a four-cable wrist device. In one embodiment, the mechanism includes: a) a base; b) a first drive cable, a second drive cable, a third drive cable, and a fourth drive cable, each drive cable having one end connected to the four-cable wrist device and the other end connected to the base; c) a first cam, a second cam, and a third cam, each cam being used to independently control one degree of freedom of the four-cable wrist device; each of the first, second, and third cams includes two cable adjustment surfaces, such that a specific pair of drive cables from the first, second, third, or fourth drive cables is positioned between the two cable adjustment surfaces. On one of the cable adjustment surfaces, two other drive cables are placed on the other cable adjustment surface; when the first cam is driven to rotate, the first and third drive cables can be simultaneously relaxed or tightened, while the second and fourth drive cables are correspondingly tightened or relaxed simultaneously; when the second cam is driven to rotate, the first and second drive cables can be simultaneously relaxed or tightened, while the third and fourth drive cables are correspondingly tightened or relaxed simultaneously; and when the third cam is driven to rotate, the second and third drive cables can be simultaneously relaxed or tightened, while the first and fourth drive cables are correspondingly tightened or relaxed simultaneously.

[0064] In one embodiment, the first, second, and third cams are used to control the pitch, yaw, and clamping actions of the four-cable wrist device, respectively.

[0065] In one embodiment, the base includes three drive connectors for connecting the first, second, and third cams to a drive device, respectively.

[0066] In one embodiment, the drive device is driven by a motor or manually controlled.

[0067] In one embodiment, the base includes at least one post for connecting the first, second, third, and fourth drive cables.

[0068] In one embodiment, the mechanism further includes one or more sets of guide pulleys, which respectively form a first drive module, a second drive module and a third drive module with the first cam, the second cam and the third cam.

[0069] In one embodiment, the first drive module includes a first cam, a guide pulley 321, a guide pulley 322, a guide pulley 323, a guide pulley 324, a guide pulley 331, a guide pulley 333, a guide pulley 334, and a guide pulley 335. The first drive cable sequentially passes around the guide pulley 323, the first cam 351, and the guide pulley 325; the second drive cable sequentially passes around the guide pulley 333, the first cam 351, and the guide pulley 335; the third drive cable sequentially passes around the guide pulley 321, the guide pulley 322, the first cam 351, and the guide pulley 324; and the fourth drive cable sequentially passes around the guide pulley 331, the guide pulley 332, the first cam 351, and the guide pulley 334. The first and second drive cables are placed on the same cable adjustment surface of the first cam; and the third and fourth drive cables are placed on another cable adjustment surface of the first cam.

[0070] In one embodiment, the second drive module includes a second cam 352, a guide pulley 324, a guide pulley 325, a guide pulley 326, a guide pulley 327, a guide pulley 334, a guide pulley 335, a guide pulley 336, and a guide pulley 337. The first drive cable sequentially passes around the guide pulley 325, the second cam 352, and the guide pulley 327; the second drive cable sequentially passes around the guide pulley 335, the second cam 352, and the guide pulley 326; the third drive cable sequentially passes around the guide pulley 324, the second cam 352, and the guide pulley 336; and the fourth drive cable sequentially passes around the guide pulley 334, the second cam 352, and the guide pulley 337. The first and third drive cables are placed on the same cable adjustment surface of the second cam; the second and fourth drive cables are placed on another cable adjustment surface of the second cam.

[0071] In one embodiment, the third drive module includes the third cam, a guide pulley 326, a guide pulley 327, a guide pulley 336, and a guide pulley 337. The first drive cable passes sequentially around the guide pulley 327 and the third cam 353; the second drive cable passes sequentially around the guide pulley 326 and the third cam 353; the third drive cable passes sequentially around the guide pulley 336 and the third cam 353; and the fourth drive cable passes sequentially around the guide pulley 337 and the third cam 353. The first and fourth drive cables are placed on the same cable adjustment surface of the third cam; and the second and third drive cables are placed on another cable adjustment surface of the third cam.

[0072] In one embodiment, the four-cable wrist device includes: a) a jaw 5 and a jaw 6 rotatably connected, each of the jaw 5 or jaw 6 including a front guide channel; b) two rear guide channels 7 fixed by a pin 10; c) a pin 11; and d) a first device drive cable, a second device drive cable, a third device drive cable, and a fourth device drive cable; the first, second, third, and fourth device drive cables sequentially bypass the front guide channel, the two rear guide channels, and the pin 11 of the jaw 5 or jaw 6, and are respectively connected to the first, second, third, and fourth drive cables.

[0073] In one embodiment, the cable adjustment surface of the first, second, or third cam has an optimized cam shape to achieve the desired movement of the four-cable wrist device.

[0074] In one embodiment, the cam shape is determined by formula (1).

[0075] In one embodiment, the four-cable wrist device is an end effector with three degrees of freedom.

[0076] The present invention also provides a medical device, which includes the mechanism described in the present invention.

[0077] The present invention further provides a surgical robot, which includes the medical device described in the present invention.

[0078] Example

[0079] One embodiment of the present invention is a medical device, the four-cable wrist device of which is such as Figures 1A to 1D As shown. The cam-based rear-end drive mechanism 300 for controlling the four-cable wrist device is as follows. Figures 3A to 3C As shown.

[0080] In this embodiment, the four-cable wrist device is deflected by a drive cam 351. Four drive cables are connected in pairs to opposite sides of the cam 351 and to the four-cable wrist device. Jaws 5 and 6 are each connected to two specific drive cables. Two drive cables located on the same side of the two front guide channels of the two jaws are supported by one side of the cam 351. The two jaws are rotatably mounted on pins 9. A total of four drive cables sequentially pass around the two front guide channels on jaws 5 and 6, then around the rear guide channel 7 fixed by pin 10, and then around pin 11. When the cam 351 rotates, it drives the two drive cables connected to each jaw to move in opposite directions. The four drive cables pull the front guide channels to rotate, generating a torque in the same direction on the front guide channels of the two jaws, thereby controlling the four-cable wrist device to deflect. The lever arm of the torque depends on the distance between the central axis of pin 9 and the tangent point of the drive cables and guide channels.

[0081] In this embodiment, a four-cable wrist device is controlled to achieve pitch by driving a cam 352. Four drive cables are arranged in pairs on opposite sides of the cam 352 and connected to the four-cable wrist device. Jaws 5 and 6 are each connected to two specific drive cables. The two drive cables located in the front guide channel of one jaw are supported by one side of the cam 352. The two drive cables located in the front guide channel of the other jaw are supported by the other side of the cam 352. The two jaws are rotatably mounted on pins 9. A total of four drive cables sequentially pass around the two front guide channels on jaws 5 and 6, then around the rear guide channel 7 fixed by pin 10, and then around pin 11. When the cam 352 rotates, it drives the two drive cables connected to each jaw to move in the same direction, while the drive cables on the two jaws move in opposite directions. The four drive cables pull the rear guide channel 7 to rotate, thereby controlling the four-cable wrist device to achieve pitch.

[0082] In this embodiment, a four-cable wrist device is controlled by a drive cam 353 to perform clamping. Four drive cables are arranged in pairs on opposite sides of the cam 353 and connected to the four-cable wrist device. Jaws 5 and 6 are each connected to two specific drive cables. Two drive cables located on opposite sides of the two front guide channels of the two jaws are supported by one side of the cam 353. The two jaws are rotatably mounted on pins 9. A total of four drive cables sequentially pass around the two front guide channels on jaws 5 and 6, then around the rear guide channel 7 fixed by pin 10, and then around pin 11. When the cam 353 rotates, it drives the two drive cables connected to each jaw to move in opposite directions. The four drive cables pull the front guide channels to rotate, generating torques in opposite directions on the front guide channels of the two jaws, thereby controlling the four-cable wrist device to perform the clamping action. The lever arm of the torque depends on the distance between the central axis of pin 9 and the tangent point of the drive cables and guide channels.

[0083] Advantages of this invention. First, the cam-based rear-end transmission mechanism of this invention enables completely decoupled control of the three degrees of freedom of a four-cable wrist device. The cam-based rear-end transmission mechanism can be driven by either a motor or a handheld device. The four-cable wrist device has three degrees of freedom. Existing rear-end transmission mechanisms typically drive four-cable wrist devices in a coupled manner. As shown in patents WO2022227856A1 and WO2010009221A2, there is a coupling relationship between the three cylindrical winches. Controlling one degree of freedom of the four-cable wrist device requires the coordinated rotation of two to three cylindrical winches. Furthermore, some patents use gear and rack structures to drive four-cable wrist devices, such as the rear-end transmission mechanism in patent WO2010009221A2. This design still requires the coordinated rotation of gears to control one degree of freedom of the four-cable wrist device. In contrast, each cam in the cam-based rear transmission mechanism of this invention can simultaneously control four drive cables, and the cam shape can be optimized so that the three cams can independently control the three degrees of freedom of the four-cable wrist device, thereby achieving complete decoupling control of the three degrees of freedom of the four-cable wrist device. This complete decoupling method enables manual control of the four-cable wrist device.

[0084] Secondly, the cam shape optimization method of this invention makes the cam-based rear-end transmission mechanism more versatile, adapting to specific length variation relationships between the four drive cables in more situations. Existing rear-end transmission mechanisms for driving four-cable wrist devices, such as patents WO2010009221A2 and WO2022227856A1, assume that when the rear-end transmission mechanism drives the four-cable wrist device, the length change of the drive cables is proportional to the angle change of the jaws. These patents also assume that the length changes of the four drive cables are equal and that the directions of change are opposite in pairs. However, in reality, for many four-cable wrist devices, the length change of the drive cables does not change linearly with the pitch angle during pitch motion, as shown in patent WO2010009221A2. The cam-based rear-end transmission mechanism of this invention, through cam shape optimization, can maintain a proportional relationship between the motor rotation angle and the jaw opening / closing angle in the four-cable wrist device. The cam shape optimization method enables the cam-based rear-end transmission mechanism to adapt to more types of four-cable wrist devices.

Claims

1. A mechanism for controlling a four-cable wrist device, comprising: a. a base; b. A first drive cable, a second drive cable, a third drive cable and a fourth drive cable, one end of each drive cable being connected to the four-cable wrist device and the other end being connected to the base; c. A first cam, a second cam, and a third cam, each cam being used to independently control one degree of freedom of the four-cable wrist device; each of the first, second, and third cams includes two cable adjustment surfaces such that a particular pair of drive cables of the first, second, third, or fourth drive cables are placed on one of the two cable adjustment surfaces, and the other two drive cables are placed on the other cable adjustment surface. Its features are: When the first cam is driven to rotate, the first and third drive cables can be simultaneously relaxed or tightened, while the second and fourth drive cables are correspondingly tightened or relaxed simultaneously. When the second cam is driven to rotate, the first and second drive cables can be simultaneously relaxed or tightened, while the third and fourth drive cables are correspondingly tightened or relaxed simultaneously. as well as When the third cam is driven to rotate, the second and third drive cables can be simultaneously relaxed or tightened, while the first and fourth drive cables are correspondingly tightened or relaxed simultaneously.

2. The mechanism according to claim 1, characterized in that: The first, second, and third cams are used to control the pitch, yaw, and clamping actions of the four-cable wrist device, respectively.

3. The mechanism according to claim 1, characterized in that: The base includes three drive connectors for connecting the first, second, and third cams to a drive device, respectively.

4. The mechanism according to claim 3, characterized in that: The drive device is driven by a motor or manually controlled.

5. The mechanism according to claim 1, characterized in that: The base includes at least one post for connecting the first, second, third and fourth drive cables.

6. The mechanism according to claim 1, characterized in that: The mechanism further includes one or more sets of guide pulleys, which together with the first cam, the second cam, and the third cam form a first drive module, a second drive module, and a third drive module, respectively.

7. The mechanism according to claim 6, characterized in that: The first drive module includes the first cam, a guide pulley 321, a guide pulley 322, a guide pulley 323, a guide pulley 324, a guide pulley 331, a guide pulley 333, a guide pulley 334, and a guide pulley 335. The first drive cable passes sequentially around the guide pulley 323, the first cam 351, and the guide pulley 325; The second drive cable passes sequentially around the guide pulley 333, the first cam 351, and the guide pulley 335; The third drive cable passes sequentially around the guide pulley 321, the guide pulley 322, the first cam 351, and the guide pulley 324; The fourth drive cable passes sequentially around the guide pulley 331, the guide pulley 332, the first cam 351, and the guide pulley 334; The first and second drive cables are positioned on the same cable adjustment surface of the first cam; the third and fourth drive cables are positioned on another cable adjustment surface of the first cam.

8. The mechanism according to claim 6, characterized in that: The second drive module includes a second cam 352, a guide pulley 324, a guide pulley 325, a guide pulley 326, a guide pulley 327, a guide pulley 334, a guide pulley 335, a guide pulley 336, and a guide pulley 337. The first drive cable passes sequentially around the guide pulley 325, the second cam 352, and the guide pulley 327; The second drive cable passes sequentially around the guide pulley 335, the second cam 352, and the guide pulley 326; The third drive cable passes sequentially around the guide pulley 324, the second cam 352, and the guide pulley 336; The fourth drive cable passes sequentially around the guide pulley 334, the second cam 352 and the guide pulley 337; The first and third drive cables are placed on the same cable adjustment surface of the second cam; the second and fourth drive cables are placed on another cable adjustment surface of the second cam.

9. The mechanism according to claim 6, characterized in that: The third drive module includes the third cam, a guide pulley 326, a guide pulley 327, a guide pulley 336, and a guide pulley 337. The first drive cable passes sequentially around the guide pulley 327 and the third cam 353; The second drive cable passes sequentially around the guide pulley 326 and the third cam 353; The third drive cable passes sequentially around the guide pulley 336 and the third cam 353; The fourth drive cable passes sequentially around the guide pulley 337 and the third cam 353; The first and fourth drive cables are positioned on the same cable adjustment surface of the third cam; the second and third drive cables are positioned on another cable adjustment surface of the third cam.

10. The mechanism according to claim 1, characterized in that: The four-cable wrist device includes: a. A jaw 5 and a jaw 6 rotatably connected, each of the jaw 5 or jaw 6 including a front guide channel; b. Two rear guide channels 7 fixed by a pin 10; c. A pin 11; and d. A first instrument drive cable, a second instrument drive cable, a third instrument drive cable, and a fourth instrument drive cable; The first, second, third, and fourth instrument drive cables sequentially bypass the front guide channel, the two rear guide channels, and the pin 11 of the jaw 5 or jaw 6, and are respectively connected to the first, second, third, and fourth drive cables.

11. The mechanism according to claim 1, characterized in that: The cable adjustment surface of the first, second, or third cam has an optimized cam shape to achieve the desired movement of the four-cable wrist device.

12. The mechanism according to claim 11, characterized in that: The cam shape is determined by the following function, which describes how the lengths of the first, second, third, or fourth drive cables change with the cam. ( = Rotation angle of the first cam, second cam, and third cam) change: , for and The angle between them; It is one of the two intersection points of the line connecting the centers of the two nearest guide pulleys and the outline of the guide pulley; It is half the distance between the axes of the two farthest guide pulleys.

13. The mechanism according to claim 1, characterized in that: The four-cable wrist device is an end effector with three degrees of freedom.

14. A medical device, characterized in that: The medical device includes the mechanism as described in any one of claims 1 to 12.

15. A surgical robot, characterized in that: The surgical robot includes the medical device as described in claim 13.

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