A two-degree-of-freedom parallel RCM end effector for minimally invasive surgery

Abstract

This invention discloses a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery, comprising a fixed platform, a moving platform, a transmission unit, a central shaft, and an execution unit. The fixed platform includes a base and two drive motor modules mounted on the base; an operating handle is fixed to the front of the moving platform; and the central shaft is located between the fixed and moving platforms. The transmission unit comprises three sets of RCM links, consisting of links to the fixed platform, the moving platform, and the execution unit. Each set of links includes two parallel links, and these parallel links are connected by synchronous pulleys and synchronous belts. The three sets of RCM links and the central shaft connect the fixed platform to the moving platform and the moving platform to the execution unit, allowing the entire structure to define a fixed distal point at which the actuator of the execution unit is located. This invention decouples the execution position from the attitude of the actuator, allowing the actuator to freely adjust its attitude during operation and improving its obstacle avoidance capabilities.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, and in particular relates to a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery. Background Technology

[0002] Minimally invasive surgery involves inserting specialized instruments, physical energy, or chemical agents into the human body through tiny incisions to perform procedures such as inactivation, removal, repair, or reconstruction of lesions, deformities, and traumas to achieve therapeutic goals. The development of robot-assisted surgery aims to assist surgeons in treating patients while minimizing life-threatening factors, with the goal of preventing prolonged hospital stays and increased complications associated with open surgery.

[0003] Minimally invasive surgical robots mainly consist of a console system, a manipulator system, and an imaging system. The end effector of the manipulator system typically includes an RCM (Remote Control Mechanism) and surgical instruments mounted on the RCM. The RCM, utilizing its parallel mechanism, allows for greater freedom of manipulation of the lesion site. With the assistance of the surgeon and the imaging system, the end effector's posture can be adjusted to ultimately enable the surgical robot to perform its surgical procedures.

[0004] The design of the end effector configuration for minimally invasive surgical robots is one of the key issues in robotic systems. The end effector of a minimally invasive surgical robot must satisfy the surgical instrument's ability to operate on the lesion site, while also providing protection for the surgical incision and soft tissue, facilitating surgical operations for the surgeon, and not obstructing the surgeon's field of vision. The design of the mechanism must also consider its interaction with the surgeon and the surgical site, achieving lightweight and miniaturization while meeting flexibility, safety, and maneuverability requirements, and satisfying the hygienic conditions for surgical use. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery, meeting the requirements of relatively small incisions, confined space operations, soft tissue protection, and high surgical path accuracy in minimally invasive surgery.

[0006] This invention provides a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery, comprising a fixed platform, a moving platform, a central shaft, a fixed platform link, a moving platform link, an execution unit link, and an execution unit.

[0007] The fixed platform includes a base and two motor modules mounted on the base with their axes perpendicular to each other. The output ends of the two motor modules are respectively connected to two lower connecting shafts located at the bottom of the central shaft and perpendicular to the central shaft through a connecting rod of the fixed platform, forming a revolute joint. Of the two lower connecting shafts, one is integral with the central shaft, and the other is integral with a lower connecting piece that is sleeved on the central shaft through the revolute joint.

[0008] The moving platform has two connecting rods. One end of each rod is connected to a connecting hole perpendicular to the two axes at the rear side of the moving platform to form a revolute joint. The other end of each rod is connected to two upper connecting shafts perpendicular to the central axis located at the top of the central axis to form a revolute joint. Of the two upper connecting shafts, one is integral with the central axis, and the other is integral with an upper connecting piece that is sleeved on the central axis through the revolute joint.

[0009] The execution unit is an actuator held by an actuator clamp; the end of the actuator clamp is connected to the front of the moving platform via two execution unit connecting rods. One end of each of the two execution unit connecting rods is connected to two connecting holes perpendicular to the front axis of the moving platform to form a revolute joint; the other end is connected to two actuator connecting shafts perpendicular to the axis of the actuator clamp located at the end of the actuator clamp to form a revolute joint. Of the two actuator connecting shafts, one is integral with the actuator clamp, and the other is integral with an actuator connector sleeved on the actuator clamp via a revolute joint; and the aforementioned moving platform connecting rods connected to the front and rear front connecting holes of the moving platform are also connected to the execution unit connecting rods via transmission connecting rods.

[0010] The two fixed platform links, two moving platform links, and two actuator links are divided into three groups of RCM links, which together constitute the transmission unit. Each group of RCM links includes two parallel links. The fixed platform link and the moving platform link located on the same side of the central axis, as well as the moving platform link located on the same side of the moving platform and the actuator link, are connected by synchronous pulleys and synchronous belts.

[0011] In the above structure, two motor modules drive two fixed platform connecting rods to rotate axially around the motor modules, and the two fixed platform connecting rods drive the central shaft to rotate around the rotation center of the fixed platform connecting rod. The rotation center of the fixed platform is the intersection of the axes of the two lower connecting shafts. Furthermore, the two fixed platform connecting rods control the synchronous movement of two moving platform connecting rods via a synchronous belt, and the two moving platform connecting rods drive the moving platform to rotate around the rotation center of the moving platform connecting rod. The rotation center of the moving platform is the intersection of the axes of the two upper connecting shafts. The two moving platform connecting rods further control the synchronous movement of two actuator connecting rods via a synchronous belt and a transmission connecting rod, thereby driving the rotation of the actuator and ensuring that the actuator's point of action is always located at the far-end stationary point of the mechanism.

[0012] The advantages of this invention are:

[0013] 1. The present invention provides a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery. By designing three sets of parallel RCM linkage mechanisms, the constraints between the mechanisms are very compact, resulting in higher accuracy and stability compared to serial mechanisms.

[0014] 2. The present invention provides a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery. The designed RCM mechanism decouples the end effector posture and the robotic arm motion, optimizes the control method, and improves control accuracy.

[0015] 3. The present invention provides a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery. The synchronous belt design simplifies the complex design of the traditional double parallelogram mechanism and allows the distal fixed point of the RCM mechanism to be located outside the main body of the mechanism, thus optimizing the problem of the doctor's narrow field of vision and improving the working space and dexterity of the mechanism. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the two-degree-of-freedom parallel RCM end effector of the present invention;

[0017] Figure 2 This is a schematic diagram of the fixed platform linkage structure in the two-degree-of-freedom parallel RCM end effector of the present invention;

[0018] Figure 3 This is a schematic diagram of the moving platform linkage structure in the two-degree-of-freedom parallel RCM end effector of the present invention;

[0019] Figure 4 This is a schematic diagram of the actuator fixture structure in the two-degree-of-freedom parallel RCM end effector of the present invention;

[0020] Figure 5 This is a schematic diagram of the transmission component structure in the two-degree-of-freedom parallel RCM end effector of the present invention;

[0021] Figure 6 This is a schematic diagram of the integrated transmission linkage structure design in the transmission assembly.

[0022] In the picture:

[0023] 1-Fixed platform 2-Moving platform 3-Central axis

[0024] 4-Fixed platform link; 5-Moving platform link; 6-Actuator unit link

[0025] 7-Execution Unit 101-Base 102-Drive Motor Module

[0026] 201-Square platform 202-Strip platform 203-Connecting plate A

[0027] 204-Connecting Plate B 205-Connecting Plate C 206-Connecting Plate D

[0028] 301 - Shaft connector; 302 - Connecting shaft A; 401 - Connecting disc

[0029] 402 - Fixed platform synchronous pulley; 501 - Moving platform connecting shaft; 502 - Moving platform synchronous pulley

[0030] 701-Actuator; 702-Actuator Fixture; 702a-Fixture Connector

[0031] 702b - Actuator connecting shaft; 801 - Side synchronous pulley; 802 - Transmission connecting rod; 803 - Synchronous belt Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings.

[0033] This invention relates to a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery, comprising a fixed platform 1, a moving platform 2, a central shaft 3, a fixed platform connecting rod 4, a moving platform connecting rod 5, an execution unit connecting rod 6, an execution unit 7, and a transmission assembly, as shown below. Figure 1 As shown.

[0034] The fixed platform 1 includes a base 101 and two drive motor modules 102, denoted as motor module A and motor module B, respectively. Motor module A is fixedly mounted on the front support of the base 101, with its axis aligned in the front-rear direction. Motor module B is fixedly mounted on the left support of the base, with its axis perpendicular to the axis of motor module A and aligned in the left-right direction. The output ends of both motor modules A and B face the central axis of the base 101. Each of motor modules A and B is connected to the end of the central shaft 3 via a fixed platform connecting rod 4; the top of the central shaft 3 is connected to the moving platform 2 via two moving platform connecting rods 5.

[0035] Both the top and bottom ends of the aforementioned central shaft 3 are fitted with shaft connectors 301, and each is also designed with a connecting shaft A302 perpendicular to the axis of the central shaft 3. The shaft connector 301 is an L-shaped connector with a connecting ring on one side, which fits onto the end of the central shaft 4 to form a rotating pair. The other side of the shaft connector 301 is parallel to the central shaft 4, and its end is designed with a connecting shaft B perpendicular to the central shaft. The axis of this connecting shaft B intersects the axis of the connecting shaft A at a point located on the axis of the central shaft 3, which is the rotation center of the two fixed platform connecting rods 4.

[0036] like Figure 2 As shown, the fixed platform connecting rod 4 is an L-shaped rod with a connecting disc 401 on the outer front end and a fixed platform synchronous wheel 402 on the outer end, with their axes perpendicular to each other; the fixed platform synchronous wheel 402 has a circumferential groove, and the groove has synchronous teeth 403 designed at equal intervals, with the top of the synchronous teeth 403 not exceeding the groove opening.

[0037] The two fixed platform connecting rods 4 of the above structure are fixedly installed at the output ends of motor module A and motor module B, respectively. Among them, the fixed platform synchronous wheel 402 of the fixed platform connecting rod 4 connected to motor module B is connected to the connecting shaft A302 at the bottom of the central shaft 3 through the central hole, forming a rotating pair. The fixed platform synchronous wheel 402 of the fixed platform connecting rod 4 connected to motor module A is connected to the connecting shaft B on the shaft connector 301 sleeved at the bottom of the central shaft 3 through the central hole, forming a rotating pair. The output ends of motor module A and motor module B are equidistant from the rotation centers of the two fixed platform connecting rods 4.

[0038] The moving platform 2 has a plate-like structure, including a rear square platform 201, a front strip platform 202 (wider than the rear), and four longitudinal connecting plates of an integral structure designed circumferentially. Let the four longitudinal connecting plates be labeled A to D. Connecting plates A203 and B204 are two longitudinal connecting plates perpendicular to the moving platform 2, located at the front and rear left sides of the moving platform 2, respectively, and are connected to the bottom surface of the moving platform 2. Connecting plate C205 is a longitudinal connecting plate perpendicular to the moving platform 2, located at the front edge of the rear square platform 201, and is connected to the bottom surface of the moving platform 2. Connecting plate D206 is an L-shaped plate, with one side parallel to the moving platform 2 and connected to the middle of the strip platform 202, and the other side corresponding to the position of connecting plate C205.

[0039] The aforementioned structure connects the moving platform 2 to the top of the central shaft 4 via a moving platform connecting rod 5. The moving platform connecting rod 5 is structurally similar to the fixed platform connecting rod 4, except that the outer front end of the moving platform connecting rod 5 is designed as a moving platform connecting shaft 501. The axis of the moving platform connecting shaft 501 is perpendicular to the axis of the moving platform synchronous pulley 502 at the end of the moving platform rod 5, and the end of the moving platform connecting shaft 501 is a D-type connector. Figure 3 As shown.

[0040] In the above structure, one of the two moving platform connecting rods 5 is connected to the connecting shaft A302 at the top of the central shaft 3 through the central hole of the moving platform synchronous wheel 501, forming a rotating pair; the moving platform connecting shaft 501 passes through and is connected to the connecting plate B204 in the moving platform 2 through the through hole, forming a rotating pair.

[0041] Another moving platform connecting rod 2 is connected to the connecting shaft B in the L-shaped connector 301 at the top of the central shaft 3 through the central hole of the synchronous wheel 501, forming a rotating pair; the moving platform connecting shaft 501 passes through and is connected to the connecting plate C205 in the moving platform 2 through the through hole, forming a rotating pair.

[0042] The axes of the through holes on the connecting plate B204 and the connecting plate C205 are perpendicular to each other and are equidistant from the rotation centers of the two moving platform connecting rods 5. The rotation center is the intersection of the axis of the connecting shaft B on the top shaft connector 301 of the central shaft 4 and the axis of the top connector A302 of the central shaft 4. This intersection point is located on the axis of the central shaft 4.

[0043] The execution unit 7 includes an actuator 701 and an actuator clamp 702. The front part of the actuator clamp 702 is a holding section, which clamps and fixes the actuator 701 to its end. Figure 4 As shown, the front end of the actuator clamp 702 is designed with an external thread section, which is threadedly connected to the internal thread section at the rear end of the actuator clamp 702. An actuator connecting shaft 702b is designed on the side of the rear end of the actuator clamp 702. At the same time, a clamp connector 702a is installed at the end of the actuator clamp 702. Its structure is the same as that of the aforementioned shaft connector 301, and it is sleeved on the end of the actuator clamp 702 through a connecting ring.

[0044] The aforementioned execution unit 7 is connected to the front of the moving platform 2 via two execution unit connecting rods 6; the execution unit connecting rods 6 are L-shaped connecting rods. Let the two execution unit connecting rods 6 be rod A and rod B, with a connecting shaft E at one end and a D-shaped hole at the shaft end; the other end of each execution unit connecting rod 6 has a cylindrical hole, and the connecting shaft E is perpendicular to the axis of the cylindrical hole. Rod A has one end fitted onto the actuator connecting shaft 702b at the end of the actuator clamp 702 through the cylindrical hole, and the connecting shaft E at the other end passes through and connects to the connecting shaft through a through hole in the connecting plate A203 of the moving platform 2, forming a rotating pair; Rod B has one end fitted onto the connecting shaft on the clamp connector 702a through the cylindrical hole, and the connecting shaft E at the other end passes through and connects to the connecting shaft through a through hole in the connecting plate D206 of the moving platform 2, forming a rotating pair.

[0045] The transmission assembly is used to realize the transmission between the fixed platform 1 and the moving platform 2, and between the moving platform 2 and the execution unit 7. In addition to the synchronous pulleys in the fixed platform connecting rod 4 and the moving platform connecting rod 5, it also includes two side synchronous pulleys 801, a transmission connecting rod 802, and three synchronous belts 803. Figure 6 As shown. The two side synchronous pulleys 801 have the same structure as the fixed platform synchronous pulley 402, and are respectively connected and fixed to the D-type connectors at the ends of the connecting shafts installed on the connecting plates A203 and B204 of the aforementioned moving platform 2 through the central D-type holes. The transmission connecting rod 802 is respectively connected and fixed to the D-type holes at the ends of the connecting shafts installed on the connecting plates C205 and D206 of the aforementioned moving platform 2 through the D-type holes at both ends, forming a synchronously moving rigid body; the transmission connecting rod 802 can also be designed as an integral structure with the connecting shaft installed on the connecting plate C205 of the moving platform 2 for easy assembly, such as... Figure 5 As shown.

[0046] Three synchronous belts 803 are respectively fitted between the synchronous pulleys sleeved on the connecting shafts A302 at both ends of the central shaft 3, between the synchronous pulleys connected to the shaft connecting parts 301 sleeved on both ends of the central shaft 3, and between the two side synchronous pulleys 801, so that the rotation angle of each synchronous pulley is consistent.

[0047] In this invention, a two-degree-of-freedom parallel RCM end effector for minimally invasive surgery comprises three groups of RCM links: two fixed platform links, two moving platform links, and two actuator links, forming a transmission unit. Each group of RCM links includes two parallel links. The fixed platform link and the moving platform link located on the same side of the central axis, as well as the moving platform link and the actuator link located on the same side of the moving platform, are connected by a synchronous pulley and a synchronous belt. During operation, the drive motor module 1 drives the two fixed platform links 4 to rotate axially around motor module A and motor module B, respectively. The two fixed platform links 4 can respectively drive the central axis 3 to rotate around the rotation center of the fixed platform link 4. Furthermore, the two fixed platform links 4 control the synchronous movement of the two moving platform links 5 via a synchronous belt. The two moving platform links 5 can respectively drive the moving platform 2 to rotate around the rotation center of the moving platform link 5. The central shaft 4 is located on the line connecting the rotation centers of the moving platform connecting rod 4 and the moving platform connecting rod 5, limiting the distance between the base 101 and the moving platform 2. The central shaft 4 constrains the spatial position of the moving platform connecting rod 5, compensating for the insufficient vertical constraint caused by the flexible synchronous belt. The two moving platform connecting rods 5 further control the synchronous movement of the two actuator connecting rods 6 through the synchronous belt 803 and the transmission connecting rod 802. The two actuator connecting rods 6 control the rotational movement of the actuator clamp 802 and the actuator 801 rotatably connected to them, ensuring that the point of action of the actuator 801 is always located at the far end of the overall structure.

[0048] In this invention, the actuator 701 can be replaced according to surgical requirements, and the screw-in length of the front end of the actuator clamp 702 can be changed by limiting the length of the external thread at the front end of the actuator clamp 702 to adapt to the length of the actuator 701, ensuring that the action point of the actuator 701 is always located at the far end of the mechanism.

Claims

1. A two-degree-of-freedom parallel RCM end effector for minimally invasive surgery, characterized in that: This includes a fixed platform, a moving platform, a central axis, a fixed platform connecting rod, a moving platform connecting rod, an execution unit connecting rod, and an execution unit; The fixed platform includes a base and two motor modules mounted on the base with their axes perpendicular to each other; the fixed platform has two connecting rods, and the output ends of the two motor modules are respectively connected to two lower connecting shafts located at the bottom of the central shaft and perpendicular to the central shaft through the fixed platform connecting rods to form a rotating pair; of the two lower connecting shafts, one is integrated with the central shaft, and the other is integrated with a lower connecting piece sleeved on the central shaft through the rotating pair; The main body of the moving platform is a plate-like structure, including a rear square platform, a front strip platform narrower than the rear, and four longitudinal connecting plates with an integrated circumferential structure. Let these four longitudinal connecting plates be labeled A through D. Connecting plates A and B are two longitudinal connecting plates perpendicular to the moving platform, designed on the same side of the front and rear of the moving platform, respectively, and connected to the bottom surface of the moving platform. Both have connecting holes for connecting a set of moving platform connecting rods to the execution unit connecting rods. Connecting plate C is a longitudinal connecting plate perpendicular to the moving platform, designed at the front edge of the rear square platform, and connected to the bottom surface of the moving platform. Connecting plate D is an L-shaped plate, with one side parallel to the moving platform and connected to the middle of the strip platform, and the other side corresponding to the position of connecting plate C. Both have corresponding connecting holes for connecting another set of moving platform connecting rods to the execution unit connecting rods. The moving platform has two connecting rods. One end is connected to two connecting holes perpendicular to the front axis of the rear side of the moving platform to form a rotating pair. The other end is connected to two upper connecting shafts perpendicular to the central axis located at the top of the central axis to form a rotating pair. Of the two upper connecting shafts, one is integral with the central axis, and the other is integral with an upper connecting piece that is sleeved on the central axis through the rotating pair. The execution unit is an actuator held by an actuator clamp; the end of the actuator clamp is connected to the front of the moving platform through two execution unit connecting rods; one end of the two execution unit connecting rods is connected to the two connecting holes on the front side of the moving platform perpendicular to the two front axes to form a revolute joint; the other end is connected to two actuator connecting shafts located at the end of the actuator clamp perpendicular to the axis of the actuator clamp to form a revolute joint; one of the two actuator connecting shafts is integral with the actuator clamp, and the other is integral with the actuator connecting piece sleeved on the actuator clamp through the revolute joint; and the moving platform connecting rod connected to the two connecting holes on the rear side of the moving platform perpendicular to the two front axes is also connected to the execution unit connecting rod through a transmission connecting rod; The two fixed platform connecting rods, two moving platform connecting rods, and two actuator connecting rods are divided into three groups of RCM connecting rods, which together constitute the transmission unit. Each group of RCM connecting rods includes two parallel connecting rods, a fixed platform connecting rod and a moving platform connecting rod located on the same side of the central axis, and a moving platform connecting rod located on the same side of the moving platform and an actuator connecting rod, which are driven by a synchronous pulley and a synchronous belt. Two motor modules drive two fixed platform connecting rods to rotate axially around the motor modules. Each fixed platform connecting rod drives a central shaft to rotate around its rotation center. The rotation center of the fixed platform is the intersection of the axes of the two lower connecting shafts. Furthermore, the two fixed platform connecting rods control the synchronous movement of two moving platform connecting rods via a synchronous belt. Each moving platform connecting rod drives the moving platform to rotate around its rotation center. The rotation center of the moving platform is the intersection of the axes of the two upper connecting shafts. The two moving platform connecting rods further control the synchronous movement of two actuator connecting rods via a synchronous belt and transmission connecting rods, thereby driving the rotation of the actuator and ensuring that the actuator's point of action is always located at the far end of the overall structure.

2. The two-degree-of-freedom parallel RCM end effector for minimally invasive surgery as described in claim 1, characterized in that: The specific connection method between the fixed platform connecting rod and the central axis is as follows: The lower connector fitted onto the central shaft is an L-shaped connector with a connecting ring on one side, which fits onto the end of the central shaft to form a rotating pair. The other side of the lower connector is parallel to the central shaft, and the end is designed with a lower connecting shaft perpendicular to the central shaft. The fixed platform connecting rod is an L-shaped rod with a connecting plate on the outer front end for connecting to the output end of the motor module. The outer end of the fixed platform has a synchronous wheel perpendicular to the axis of the connecting plate. The central opening of the synchronous wheel connects to the lower connecting shaft at the bottom of the central shaft.

3. The two-degree-of-freedom parallel RCM end effector for minimally invasive surgery as described in claim 1, characterized in that: The specific connection method between the moving platform connecting rod, the central shaft, and the moving platform is as follows: The upper connector fitted onto the central shaft is an L-shaped connector with a connecting ring on one side, which fits onto the end of the central shaft to form a rotating pair. The other side of the upper connector is parallel to the central shaft, and the end is designed with an upper connecting shaft perpendicular to the central shaft. The two moving platform connecting rods are L-shaped rods with a moving platform connecting shaft on the outer front end for connecting the moving platform. After connecting with the moving platform, the end is inserted to fix a side synchronous pulley. The end of the moving platform connecting rod is designed with a moving platform synchronous pulley, with its axis perpendicular to the moving platform connecting shaft. The central opening of the moving platform synchronous pulley connects to the upper connecting shaft at the bottom of the central shaft.

4. The two-degree-of-freedom parallel RCM end effector for minimally invasive surgery as described in claim 1, characterized in that: The output terminals of the two motor modules are equidistant from the rotation centers of the two fixed platform connecting rods; the centers of the vertical connecting holes on the rear of the moving platform are equidistant from the rotation centers of the two moving platform connecting rods.

5. The two-degree-of-freedom parallel RCM end effector for minimally invasive surgery as described in claim 1, characterized in that: The front part of the actuator clamp is a clamping section, which is clamped and fixed to the end of the actuator; the front end of the actuator clamp is designed with an external thread section, which is threadedly connected to the internal thread section at the rear of the actuator clamp.

6. The two-degree-of-freedom parallel RCM end effector for minimally invasive surgery as described in claim 1, characterized in that: The connection method between the actuator linkage, the fixture, and the moving platform is as follows: The actuator connector fitted onto the actuator fixture is an L-shaped connector with a connecting ring on one side that fits onto the end of the actuator fixture to form a rotating pair. The other side of the actuator connector is parallel to the central axis, and the end is designed with an actuator connecting shaft perpendicular to the central axis. The two actuator unit connecting rods are L-shaped rods, with the front end used to connect to the moving platform and the end designed with openings to connect to the actuator connecting shafts respectively.

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