Reconfigurable RCM parallel mechanism with three motion modes

Abstract

The application discloses a reconfigurable RCM parallel mechanism with three motion modes, and belongs to the field of mechanism and robots. The mechanism can realize three rotary motion and one translational motion, two rotary motion and one translational motion and one rotary motion and one translational motion in a plane around a remote center point through different reconfiguration modes. The mechanism comprises a base, a moving platform and four branch chains connected between the base and the moving platform. Each branch chain comprises two rotary pairs, a hook hinge, an arc-shaped moving pair and a moving pair. The first rotary pair axis of each branch chain and the first rotary pair axis of the hook hinge intersect at a point, and the point is the center of each branch arc-shaped moving pair. The second rotary pair axis of the hook hinge is parallel to the other rotary pair connected to the moving platform of the branch. The moving pair of the branch is connected to the base. The position of each branch in space is changed by locking the moving pair at different positions on the base, so as to adapt to different minimally invasive surgical application occasions.

Description

Technical Field

[0001] This invention belongs to the fields of mechanics and robotics, and specifically relates to a reconfigurable RCM parallel mechanism with three motion modes. Background Technology

[0002] Minimally invasive surgery, as a type of surgical procedure with high safety and minimal trauma, is being used more and more widely in medicine. Minimally invasive surgical robots have obvious advantages in the field of minimally invasive surgery, especially high-precision parallel robots, which can play a safer role in minimally invasive surgery.

[0003] With the development and advancement of technology, modern machine operations require mechanisms to adapt to various working environments, which necessitates mechanisms with multiple working modes exhibiting different motion characteristics. However, existing minimally invasive surgical parallel robots only possess fixed remote-center motion modes and cannot adapt to diverse minimally invasive scenarios.

[0004] Currently, common remote center motion modes include two-rotation mode, three-rotation mode, two-rotation-one-movement mode, three-rotation-one-movement mode, and one-rotation-one-movement mode in the plane. Traditional remote center motion parallel mechanisms can only satisfy one of the above motion modes. However, for different minimally invasive situations, mechanisms that can satisfy multiple motion modes are required. This invention can complete the above three remote center motion modes without reassembling the mechanism through a specific reconstruction method. Moreover, one of the motion modes has motion bifurcation characteristics, which better adapts to the high safety characteristics of the minimally invasive field. Summary of the Invention

[0005] This invention aims to overcome the problem of fixed motion modes in existing RCM parallel mechanisms and provides a reconfigurable parallel mechanism that can realize three RCM motion modes.

[0006] The solution adopted by the present invention to solve its technical problem is: a reconfigurable RCM parallel mechanism with three motion modes, consisting of a base, a moving platform and four branches connecting the moving platform and the base platform, wherein the four branches are symmetrically distributed at 90 degrees in space.

[0007] The four branches include, sequentially connected between the base and the moving platform, the first sliding joint, the first revolute joint, the arcuate sliding joint, the first Hooke hinge revolute joint, the second Hooke hinge revolute joint, and the second revolute joint in the first branch; the first sliding joint, the first revolute joint, the arcuate sliding joint, the first Hooke hinge revolute joint, the second Hooke hinge revolute joint, and the second revolute joint in the second branch; the first sliding joint, the first revolute joint, the arcuate sliding joint, the first Hooke hinge revolute joint, the second Hooke hinge revolute joint, and the second revolute joint in the third branch; the first sliding joint, the first revolute joint, the arcuate sliding joint, the first Hooke hinge revolute joint, the second Hooke hinge revolute joint, and the second revolute joint in the third branch; and the first sliding joint, the first revolute joint, the arcuate sliding joint, the first Hooke hinge revolute joint, and the Hooke hinge in the fourth branch. The second revolute joint and the second revolute joint in the fourth branch; the sliding joints of the four branches are connected to the base; the first revolute joint in the first branch of the four branches and the first revolute joint of the Hooke's hinge in the first branch converge at the intersection point of the first branch, which is the center of the arc-shaped sliding joint in the first branch; the first revolute joint in the second branch of the four branches and the first revolute joint of the Hooke's hinge in the second branch converge at the intersection point of the second branch, which is the center of the arc-shaped sliding joint in the second branch; the first revolute joint in the third branch of the four branches and the first revolute joint of the Hooke's hinge in the third branch converge at the intersection point of the first branch, which is the center of the arc-shaped sliding joint in the third branch; the first revolute joint in the fourth branch of the four branches and the first revolute joint of the Hooke's hinge in the fourth branch converge at the intersection point of the fourth branch, which is the center of the arc-shaped sliding joint in the fourth branch; the axes of the second revolute joint and the second revolute joint of the Hooke's hinge on each of the four branches are parallel to each other;

[0008] The reconfigurable parallel mechanism has three RCM motion modes, and the third motion mode has motion bifurcation characteristics. Its feature is that, in the initial pose, the position of the intersection point of each branch in space is changed by locking the prismatic joints of the four branches at different positions on the base, thereby realizing the reconfiguration of the mechanism.

[0009] Furthermore, by locking the position of the four branch sliding joints on the base, the intersection point of the four branches coincides with a point in space, which is the remote center point. At this time, the first RCM motion mode is entered, and the mechanism is a three-rotation-one-movement RCM motion mode.

[0010] Furthermore, when the mechanism is in a three-rotation-one-transition RCM motion mode, the arc-shaped sliding joint of the first branch, the arc-shaped sliding joint of the second branch, the first rotational joint of the third branch, and the first rotational joint of the fourth branch all serve as driving joints.

[0011] Furthermore, by locking the positions of the four branch sliding joints on the base, the intersection points of the first, second, and fourth branches coincide at a single point in space, which is the remote center point. In addition, the intersection point of the third branch is separated from the remote center point by a fixed distance. At this time, the second RCM motion mode is entered, which is an RCM motion mode of two rotations and one movement.

[0012] Furthermore, when the mechanism is in a two-rotation-one-movement (RCM) motion mode, the arc-shaped sliding joint of the first branch, the arc-shaped sliding joint of the second branch, and the first rotational joint of the fourth branch all serve as driving joints.

[0013] Furthermore, by locking the positions of the four branch sliding joints on the base, the intersection points of the four branches are separated into a single point in space, which is the remote center point. The intersection points of the four branches are equidistant from the remote center point, at which point the third RCM motion mode is entered.

[0014] Furthermore, when the moving platform is parallel to the base plane, it is the initial configuration of the third motion mode, which is also the motion bifurcation configuration. In the initial configuration, the instantaneous motion mode of the mechanism is two rotations and one translating motion. In order to ensure the controllability of the instantaneous motion in the initial configuration of the reconfigurable remote center motion mechanism, the arc-shaped translating joint of the first branch, the arc-shaped translating joint of the second branch, the first revolute joint of the third branch, or the first revolute joint of the fourth branch all serve as driving joints.

[0015] Furthermore, when the mechanism enters the general configuration from the initial configuration of the third motion mode through the arc-shaped gliding joint of the first branch, the arc-shaped gliding joint of the second branch, and the first rotational joint of the third branch as driving joints, the motion mode switches to a rotation-translation RCM motion mode in the XOZ plane; at this time, the arc-shaped gliding joint of the first branch and the arc-shaped gliding joint of the second branch of the mechanism serve as driving joints.

[0016] Furthermore, when the mechanism enters the general configuration from the initial configuration of the third motion mode through the arc-shaped gliding joint of the first branch, the arc-shaped gliding joint of the second branch, and the first rotational joint of the fourth branch as driving joints, the motion mode switches to a rotation-translation RCM motion mode in the YOZ plane; at this time, the arc-shaped gliding joint of the first branch and the arc-shaped gliding joint of the second branch of the mechanism serve as driving joints.

[0017] Beneficial effects: The reconfigurable parallel mechanism proposed in this invention can realize three RCM motion modes: one rotation and one movement, two rotations and one movement, and three rotations and one movement. Moreover, the initial configuration of the one rotation and one movement RCM motion mode has motion bifurcation characteristics, which can enter one rotation and one movement RCM motion modes in two different planes. This invention can realize the conversion of the mechanism's motion mode by locking the sliding pairs connected to the base in the four branches at different positions on the base, without the need to reassemble the mechanism. Attached image description:

[0018] Figure 1 It is a three-rotation-one-movement RCM motion mode.

[0019] Figure 2 It refers to the position of the branch moving joint on the base during the three-rotation-one-movement RCM motion mode.

[0020] Figure 3 It is a two-rotation-one-movement RCM motion mode.

[0021] Figure 4 It refers to the position of the branch moving joint on the base during the two-rotation-one-movement RCM motion mode.

[0022] Figure 5 It is a bifurcation position type of RCM motion mode of rotation and movement.

[0023] Figure 6 It is a rotation-movement (RCM) motion mode within the XOZ plane.

[0024] Figure 7 It is a rotation-transition RCM motion mode within the YOZ plane.

[0025] Figure 8 This refers to the position of the branch sliding joint on the base during a rotational and traversing RCM motion mode. (See attached diagram for reference numerals.)

[0026] A—Base, B—Moving platform, O—Remote center point, P11—First sliding joint in the first branch, R11—First revolute joint in the first branch, Pr1—Arc sliding joint in the first branch, U11—First revolute joint of the Hooke's hinge in the first branch, U12—Second revolute joint of the Hooke's hinge in the first branch, R12—Second revolute joint in the first branch, O1—Intersection point in the first branch; P21—First sliding joint in the second branch, R21—First revolute joint in the second branch, Pr2—Arc sliding joint in the second branch, U21—First revolute joint of the Hooke's hinge in the second branch, U22—Second revolute joint of the Hooke's hinge in the second branch, R22—Second revolute joint in the second branch, O2 —The confluence point in the second branch; P31—The first prismatic joint in the third branch, R31—The first revolute joint in the third branch, Pr3—The arc prismatic joint in the third branch, U31—The first revolute joint of the Hooke hinge in the third branch, U32—The second revolute joint of the Hooke hinge in the third branch, R32—The second revolute joint in the third branch, O3—The confluence point in the third branch; P41—The first prismatic joint in the fourth branch, R41—The first revolute joint in the fourth branch, Pr4—The arc prismatic joint in the fourth branch, U41—The first revolute joint of the Hooke hinge in the fourth branch, U42—The second revolute joint of the Hooke hinge in the fourth branch, R42—The second revolute joint in the fourth branch, O4—The confluence point in the fourth branch. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] 1. For example Figure 1As shown, a reconfigurable parallel mechanism capable of realizing three RCM motion modes is characterized in that: the reconfigurable parallel mechanism includes a base, a moving platform, and four branches connecting the base and the moving platform in parallel; the four branches include, in the first branch, a first prismatic joint P11, a first revolute joint R11, an arcuate prismatic joint Pr1, a first Hooke hinge revolute joint U11, a second Hooke hinge revolute joint U12, and a second revolute joint R12, sequentially connected between the base A and the moving platform B; and in the second branch, a first prismatic joint P21, a first prismatic joint Pr1, a first prismatic joint Pr1, a first prismatic joint U11, a second prismatic joint U12, and a second prismatic joint R12, sequentially connected between the base A and the moving platform B. The first revolute joint R21 in the second branch, the arcuate prismatic joint Pr2 in the second branch, the first revolute joint U21 in the second branch, the second revolute joint U22 in the second branch, and the second revolute joint R22 in the second branch; the first prismatic joint P31 in the third branch, the first revolute joint R31 in the third branch, the arcuate prismatic joint Pr3 in the third branch, the first revolute joint U31 in the third branch, the second revolute joint U32 in the third branch, and the second revolute joint R32 in the third branch; the first prismatic joint P41 in the fourth branch, the first revolute joint R41 in the fourth branch, and the arcuate prismatic joint Pr3 in the fourth branch. The four branches are symmetrically distributed in space at 90 degrees: sliding joint Pr4, first revolute joint U41 of the Hooke's hinge in the fourth branch, second revolute joint U42 of the Hooke's hinge in the fourth branch, and second revolute joint R42 of the fourth branch. The sliding joints of the four branches are connected to the base. The first revolute joint R11 of the first branch and the first revolute joint U11 of the Hooke's hinge in the first branch converge at point O1, which is the center of the arc-shaped sliding joint Pr1 in the first branch. The first revolute joint R21 of the second branch and the first revolute joint U21 of the Hooke's hinge in the second branch converge at point O1. The branch intersection point O2 is the center of the arc-shaped sliding joint Pr2 in the second branch; the first revolute joint R31 in the third branch and the first revolute joint U31 of the Hooke hinge in the third branch intersect at the first branch intersection point O3, which is the center of the arc-shaped sliding joint Pr3 in the third branch; the first revolute joint R41 in the fourth branch and the first revolute joint U41 of the Hooke hinge in the fourth branch intersect at the fourth branch intersection point O4, which is the center of the arc-shaped sliding joint Pr4 in the fourth branch; the axes of the second revolute joints of the Hooke hinge on each of the four branches are parallel to each other;

[0029] 2. For example Figure 2 As shown, the reconfigurable parallel mechanism has three RCM motion modes, and the third RCM motion mode has motion bifurcation characteristics; in the initial pose, the prismatic joints of the four branches change the position of the intersection point of each branch in space by locking them at different positions on the base, thereby realizing the reconfiguration of the mechanism.

[0030] 3. For example Figure 1 and Figure 2 As shown, the reconfigurable parallel mechanism locks the positions of the four branch sliding joints on the base, causing the intersection points O1, O2, O3, and O4 of the four branches to coincide at a single point in space. This point is the remote center point O, and the mechanism enters the first RCM motion mode, which is a three-rotation-one-transition RCM motion mode. At this time, the arc-shaped sliding joint Pr1 of the first branch, the arc-shaped sliding joint Pr2 of the second branch, the first rotational joint R31 of the third branch, and the first rotational joint R41 of the fourth branch all act as driving joints.

[0031] 4. For example Figure 3 and Figure 4 As shown, the reconfigurable parallel mechanism locks the positions of the four branch prismatic joints on the base, causing the first branch intersection point O1, the second branch intersection point O2, and the fourth branch intersection point O4 to coincide at a single point in space. This point is the remote center point O. The third branch intersection point O3 is separated from the remote center point O by a fixed distance. The mechanism then enters a second RCM motion mode, a two-rotation-one-transition RCM motion mode. In this mode, the arc-shaped prismatic joint Pr1 of the first branch, the arc-shaped prismatic joint Pr2 of the second branch, and the first rotational joint R41 of the fourth branch all act as driving joints.

[0032] 5. For example Figure 5 and Figure 6 As shown: The reconfigurable parallel mechanism locks the positions of the four branch prismatic joints on the base, causing the intersection points O1, O2, O3, and O4 of the four branches to be separated into a single point in space, which is the remote center point O. The intersection points O1, O2, O3, and O4 are equidistant from the remote center point O, and the mechanism enters the third RCM motion mode. When the moving platform is parallel to the base plane, it is the initial configuration of the third motion mode, which is also the motion bifurcation configuration. In the initial configuration, the instantaneous motion mode of the mechanism consists of two rotations and one prismatic movement. To ensure the controllability of the instantaneous motion in the initial configuration of the reconfigurable mechanism, the arc-shaped prismatic joint Pr1 of the first branch, the arc-shaped prismatic joint Pr2 of the second branch, and the first revolute joint R31 of the third branch or the first revolute joint R41 of the fourth branch simultaneously serve as driving joints.

[0033] 6. For example Figure 7 As shown: When the reconfigurable parallel mechanism enters the general configuration from the initial configuration of the third motion mode through the arc-shaped prismatic joint Pr1 of the first branch, the arc-shaped prismatic joint Pr2 of the second branch, and the first rotational joint R31 of the third branch as driving joints, the motion mode switches to a rotation-translation RCM motion mode in the XOZ plane; at this time, the arc-shaped prismatic joint Pr1 of the first branch and the arc-shaped prismatic joint Pr2 of the second branch of the mechanism serve as driving joints.

[0034] 7. For example Figure 8 As shown: When the reconfigurable parallel mechanism enters the general configuration from the initial configuration of the third motion mode, the motion mode switches to a rotation-translation (RCM) motion mode in the YOZ plane; at this time, the arc-shaped translating joints Pr1 of the first branch and Pr2 of the second branch act as driving joints.

[0035] 8. The reconfigurable parallel mechanism of the present invention, which can realize three RCM motion modes, has a simple reconfiguration method and does not require reassembly of the mechanism during the reconfiguration process; different RCM motion modes can be applied to minimally invasive surgical occasions under different constraint conditions.

[0036] 9. The above description of the present invention is merely illustrative and not restrictive. Therefore, the embodiments of the present invention are not limited to the specific embodiments described above. If those skilled in the art are inspired by this description and make other changes or modifications without departing from the spirit and scope of the claims, all such changes or modifications shall fall within the scope of protection of the present invention.

Claims

1. A reconfigurable RCM parallel mechanism with three motion modes, characterized in that, It includes a base, a moving platform, and four branches that connect the base and the moving platform in parallel; The four branches include, in the first branch connected sequentially to the base A and the moving platform B, the first sliding joint P11, the first revolute joint R11, the arcuate sliding joint Pr1, the first revolute joint U11 of the Hooke hinge U11, the second revolute joint U12 of the Hooke hinge U12, and the second revolute joint R12; and in the second branch, the first sliding joint P21, the first revolute joint R21, the arcuate sliding joint Pr2, the first revolute joint U21 of the Hooke hinge U12, and the second revolute joint U12 of the Hooke hinge U12. Two revolute joints U22, the second revolute joint R22 in the second branch; the first prismatic joint P31 in the third branch, the first revolute joint R31 in the third branch, the arcuate prismatic joint Pr3 in the third branch, the first revolute joint U31 of the Hooke joint in the third branch, the second revolute joint U32 of the Hooke joint in the third branch, the second revolute joint R32 in the third branch; the first prismatic joint P41 in the fourth branch, the first revolute joint R41 in the fourth branch, the arcuate prismatic joint Pr4 in the fourth branch, the first revolute joint U41 of the Hooke joint in the fourth branch, the Hooke joint in the fourth branch. The second revolute joint U42 and the second revolute joint R42 in the fourth branch; the four branches are symmetrically distributed at 90 degrees in space; the sliding joints of the four branches are connected to the base; the first revolute joint R11 in the first branch of the four branches and the first revolute joint U11 of the Hooke's hinge in the first branch converge at the intersection point O1 of the first branch, which is the center of the arc-shaped sliding joint Pr1 in the first branch; the first revolute joint R21 in the second branch of the four branches and the first revolute joint U21 of the Hooke's hinge in the second branch converge at the intersection point O2 of the second branch, which is the center of the arc-shaped sliding joint Pr1 in the second branch. The center of the arc-shaped sliding joint Pr2; the first revolute joint R31 in the third branch of the four branches and the first revolute joint U31 of the Hooke hinge in the third branch converge at the intersection point O3 of the first branch, which is the center of the arc-shaped sliding joint Pr3 in the third branch; the first revolute joint R41 in the fourth branch of the four branches and the first revolute joint U41 of the Hooke hinge in the fourth branch converge at the intersection point O4 of the fourth branch, which is the center of the arc-shaped sliding joint Pr4 in the fourth branch; the axes of the second revolute joint of the Hooke hinge and the second revolute joint on each of the four branches are parallel to each other; In the initial pose, the four branch prismatic joints are locked at different positions on the base to change the position of the intersection point of each branch in space, thereby realizing the reconfiguration of the mechanism.

2. The reconfigurable RCM parallel mechanism with three motion modes according to claim 1, characterized in that: By locking the position of the four branch sliding joints on the base, the intersection points O1, O2, O3, and O4 of the four branches coincide at a single point in space, which is the remote center point O. At this point, the first RCM motion mode is entered, and the mechanism is a three-rotation-one-movement RCM motion mode.

3. The reconfigurable RCM parallel mechanism with three motion modes according to claim 2, characterized in that: When the mechanism is in the three-rotation-one-transfer (RCM) motion mode, the arc-shaped transfer joint Pr1 of the first branch, the arc-shaped transfer joint Pr2 of the second branch, the first rotational joint R31 of the third branch, and the first rotational joint R41 of the fourth branch all serve as driving joints.

4. The reconfigurable RCM parallel mechanism with three motion modes according to claim 1, characterized in that: By locking the positions of the four branch moving joints on the base, the first branch intersection point O1, the second branch intersection point O2, and the fourth branch intersection point O4 coincide at a single point in space, which is the remote center point O. In addition, the third branch intersection point O3 is separated from the remote center point O by a fixed distance. At this time, the second RCM motion mode is entered, which is a two-rotation-one-movement RCM motion mode.

5. The reconfigurable RCM parallel mechanism with three motion modes according to claim 4, characterized in that: When the mechanism is in a two-rotation-one-transfer (RCM) motion mode, the arc-shaped transfer joint Pr1 of the first branch, the arc-shaped transfer joint Pr2 of the second branch, and the first rotational joint R41 of the fourth branch all serve as driving joints.

6. The reconfigurable RCM parallel mechanism with three motion modes according to claim 1, characterized in that: By locking the positions of the four branch moving pairs on the base, the intersection points O1, O2, O3, and O4 of the four branches are separated into a single point in space, which is the remote center point O. The intersection points O1, O2, O3, and O4 of the four branches are equidistant from the remote center point O. At this point, the third RCM motion mode is entered.

7. The reconfigurable RCM parallel mechanism with three motion modes according to claim 6, characterized in that: In the third motion mode, when the moving platform is parallel to the base plane, it is the initial configuration of the mechanism and also the motion bifurcation configuration. In the initial configuration, the instantaneous motion mode of the mechanism is two rotations and one translating motion. To ensure the controllability of the instantaneous motion in the initial configuration of the reconfigurable remote center motion mechanism, the arc-shaped translating joint Pr1 of the first branch, the arc-shaped translating joint Pr2 of the second branch, the first revolute joint R31 of the third branch, or the first revolute joint R41 of the fourth branch all serve as driving joints.

8. The reconfigurable RCM parallel mechanism with three motion modes according to claim 6, characterized in that: When the mechanism moves from the initial configuration to the general configuration via the arc-shaped prismatic joint Pr1 of the first branch, the arc-shaped prismatic joint Pr2 of the second branch, and the first rotary joint R31 of the third branch as driving joints, the motion mode switches to an RCM motion mode of rotation and movement in the XOZ plane; at this time, the arc-shaped prismatic joint Pr1 of the first branch and the arc-shaped prismatic joint Pr2 of the second branch act as driving joints.

9. The reconfigurable RCM parallel mechanism with three motion modes according to claim 6, characterized in that: When the mechanism moves from the initial configuration to the general configuration via the arc-shaped prismatic joint Pr1 of the first branch, the arc-shaped prismatic joint Pr2 of the second branch, and the first rotary joint R41 of the fourth branch as driving joints, the motion mode switches to an RCM motion mode of rotation and movement in the YOZ plane; at this time, the arc-shaped prismatic joint Pr1 of the first branch and the arc-shaped prismatic joint Pr2 of the second branch act as driving joints.

Images