A minimally invasive surgical robot with a mechanical-hydraulic hybrid drive and its control method

Abstract

The present invention discloses a minimally invasive surgical robot with a mechanical-hydraulic hybrid drive, which includes a base platform, a transmission system, and an end effector. The transmission system includes two branch chains, the drive motors of the two branch chains, and an end T-shaped tube. Any one of the branch chains is composed of a connecting rod structure and a guide rail slider structure to form a mirror-image Mitsubishi-shaped mechanism, with the same configuration and symmetry. The two branch chains form a parallel mechanism, each driven by a motor. The plungers of the two branch chains respectively form a sliding pair with the two inlets of the T-shaped tube, and the outlet of the T-shaped tube forms a sliding pair with the plunger of the end effector. Liquid is enclosed in the T-shaped tube for transmission. Through the dimensions and installation methods of the branch chains, it is ensured that the end effector at the outlet of the T-shaped tube has a remote center of motion with two degrees of freedom of rotation and translation. The present invention: (1) adopts a parallel structure with relatively high stiffness; (2) adopts a mechanical-hydraulic hybrid drive, which increases the working space and has stable motion; (3) the power sources are all located on the base platform, reducing the occupied space and moment of inertia at the end during surgical operations.

Description

Technical Field

[0001] The present invention belongs to the field of medical robots, and particularly relates to a minimally invasive surgical robot with a mechanical-hydraulic hybrid drive. Background Art

[0002] Compared with open surgery, which has large incisions, slow recovery, heavy bleeding, and a long hospital stay, minimally invasive surgery has the advantages of small trauma, mild pain, and fast recovery, reducing the harm to the human body. With the progress of technology, minimally invasive surgery has gradually occupied an important position in surgical operations.

[0003] In the 1980s, robots began to enter the medical field, and the concept of medical robots began to spread. Medical surgical robots are the earliest developed and most widely used branch of medical robots. Using robots to perform minimally invasive surgery has the following advantages: (1) avoiding surgical accidents caused by reasons such as surgeon fatigue; (2) avoiding the problem of hand tremors of doctors and having higher precision.

[0004] During the minimally invasive surgery process, there is a pivot point of interaction between the surgical instrument and the patient's skin, that is, the insertion point of the surgical instrument on the skin. Due to the limitation of the pivot point, the end effector entering the human body only has four degrees of freedom of movement: three rotational degrees of freedom around the pivot point and a translational degree of freedom along the instrument feeding direction. The Remote center of motion (RCM) mechanism is an ideal special mechanism designed for the above requirements. The characteristic of this mechanism is that the output member of the mechanism can rotate around a fixed point in space and move along the axis passing through this fixed point, and there is no actual rotational pair at this fixed point. In minimally invasive surgery, the output member of the mechanism is the surgical instrument extending into the human body. The RCM mechanism can reserve sufficient vision for the surgery, leave enough surgical space, and has high safety through the degree-of-freedom limitation of the mechanism, and is widely used in the structural design of minimally invasive surgical robots.

[0005] Taylor first proposed the concept of RCM in 1992 when developing a radioactive percutaneous intervention robot. Due to different requirements for the accuracy, stiffness, degrees of freedom, working space, etc. of the mechanism in different surgical sites, and the need to optimize the RCM mechanism for different goals, a large number of different configurations of RCM mechanisms have been produced. Ye Wei et al. in China designed a new type of 2R1T RCM mechanism through symmetry, which has the advantages of convenient driving and no singular configurations in the specified space; Chen Genliang et al. from Shanghai Jiao Tong University designed an RCM mechanism with kinematic decoupling of 1R1T in the plane, which is easy to control and has high accuracy. Shim et al. abroad proposed an RCM mechanism based on trigonometric ratios for bone drilling, which has high stiffness.

[0006] At present, most of the driving mechanisms for the feeding motion of the RCM mechanism are located at the end of the RCM mechanism, which increases the rotational inertia at the end of the RCM mechanism and the occupied space at the end of the mechanism, thus having an adverse effect on the positioning accuracy of the RCM point. Summary of the Invention

[0007] Object of the Invention: The object of the present invention is to invent a minimally invasive surgical robot with a mechanical-hydraulic hybrid drive, which can reduce the occupied space and rotational inertia at the end of the RCM mechanism, thereby improving the positioning accuracy of the RCM point. At the same time, the present invention also provides a control method for the minimally invasive surgical robot proposed by the present invention, so as to realize the rotation of the end effector of the robot around the RCM point in a plane and the feeding motion along the direction of the end effector.

[0008] The minimally invasive surgical robot with a mechanical-hydraulic hybrid drive provided by the present invention can adopt the following technical solutions:

[0009] A minimally invasive surgical robot with a mechanical-hydraulic hybrid drive, comprising: a base platform, a machine drive system fixed on the base platform, and an end effector; wherein the robot drive system includes two chain drive motors, two chains, and a T-shaped tube located at the ends of the two chains; each chain includes: a first link rotatably connected to the chain drive motor, a second link hinged to the first link, a third link and a fourth link hinged to the second link, a fifth link hinged to the third link and the fourth link, a first guide rail platform hinged to the fifth link, a first slider connected to the first guide rail platform, a sixth link hinged thereto, a second guide rail platform hinged to the fourth link, a long guide rail movably connected to both the first guide rail platform and the second guide rail platform, a second slider connected to the second guide rail platform, a seventh link hinged to the second guide rail platform and the sixth link, an eighth link hinged to the sixth link, a ninth link hinged to the seventh link and the eighth link, a chain plunger hinged to the ninth link, a tenth link hinged to the chain plunger, an end slider movably connected to the tenth link, and a short guide rail movably connected to the end slider and fixed on the T-shaped tube; the long guide rail is installed on the base platform and extends upward; the chain plungers of the two chains are respectively movably connected to both ends of the T-shaped tube; the tenth links of the two chains are respectively hinged to the T-shaped tube.

[0010] Further, the inner closed figure formed by the hinged connection of the second link, the third link, the fourth link, and the fifth link is a rhombus; the inner closed figure formed by the hinged connection of the sixth link, the seventh link, the eighth link, and the ninth link is a rhombus.

[0011] Further, the movement trajectory of the hinge point of the eighth link with the chain plunger is an arc, and the arc radius satisfies:

[0012] R = l 1

[0013] Wherein, R is the radius of the circular arc, and l 1 is the effective rod length of the first connecting rod, that is, the distance between two annular circles on the first connecting rod.

[0014] Furthermore, there is a T-shaped flow channel inside the T-shaped tube, and the end effector has an end effector plunger and an end effector body; a section of liquid is enclosed in the T-shaped flow channel under the combined blocking action of the two branch chain plungers and the end effector plunger; the two branch chain plungers are arranged oppositely, the end effector plunger blocks the end of the T-shaped flow channel, and the T-shaped tube is provided with a T-shaped tube outlet, a relatively arranged first branch chain inlet and a second branch chain inlet; the two branch chain plungers respectively block the first branch chain inlet and the second branch chain inlet; the flow area of the first branch chain inlet is equal to the flow area of the second branch chain inlet.

[0015] Furthermore, the end effector rotates in a single degree of freedom within a plane of a remote motion center point fixed relative to the base platform coordinate system and makes a feeding motion along its axis direction.

[0016] Furthermore, the displacements of the two branch chain plungers and the end effector plunger satisfy the following expression:

[0017] x A A in + x B A in = x out A out

[0018] Wherein, x A is the displacement of one branch chain plunger, x B is the displacement of the other branch chain plunger, and x out is the displacement of the end effector plunger; A in is the flow area of the first branch chain inlet or the second branch chain inlet of the T-shaped tube, and A out is the flow area of the T-shaped tube outlet.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0020] (1) Adopting a parallel structure, it has higher stiffness and a compact structure;

[0021] (2) Adopting liquid transmission, it increases the working space under the same size and has a stable motion;

[0022] (3) The transmission power sources (motors) are all located at the base of the structure, reducing the occupied space and the moment of inertia at the end during surgery.

[0023] The present invention also provides a control method for the above-mentioned minimally invasive surgical robot with mechanical-hydraulic hybrid drive. When the two chain drive motors rotate in the same direction with the same angular velocity, the end effector performs a single-degree-of-freedom rotation within a plane around a remote motion center point fixed relative to the base platform coordinate system and a feeding motion along its axis direction; when the two chain drive motors rotate in the same direction with opposite angular velocities, the end effector performs a feeding motion along its axis direction.

[0024] Through this control method, the end effector of the robot manipulation realizes rotation around the RCM point within a plane and feeding motion along the direction of the end effector. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic three-dimensional structure diagram of a minimally invasive surgical robot with mechanical-hydraulic hybrid drive in the present invention;

[0026] Figure 2 is a schematic structure diagram of the mirror-image Mitsubishi rod system structure included in any one of the chains in the present invention;

[0027] Figure 3 is a schematic structure diagram of the T-shaped tube in the present invention;

[0028] Figure 4 is a schematic structure composition diagram of the end effector in the present invention;

[0029] Figure 5 is a schematic diagram of the mechanical-hydraulic hybrid drive in the present invention;

[0030] Figure 6 is a schematic diagram of the end effector pose corresponding to the end effector pose control method in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions of the present invention will be further described below with reference to the accompanying drawings.

[0032] As Figures 1 to 4 shown, a minimally invasive surgical robot with mechanical-hydraulic hybrid drive described in the present invention includes: a base platform (1), a machine drive system fixed on the base platform, and an end effector (22). The robot drive system includes two chain drive motors (2), two chains, and a T-shaped tube (21) located at the ends of the two chains. The two chains form a parallel structure, with the same configuration and symmetry.

[0033] Since the two chains have the same configuration and symmetry, the two chains will be described together below.

[0034] Any one of the branches includes: a first connecting rod (3) rotatably connected to the branch drive motor (2); a second connecting rod (5) hinged to the first connecting rod (3); a third connecting rod (4) and a fourth connecting rod (6) hinged to the second connecting rod (5); a fifth connecting rod (7) hinged to the third connecting rod (4) and the fourth connecting rod (6); a first guide rail platform (8) hinged to the fifth connecting rod (7); a first slider (9) bolted to the first guide rail platform (8) and a sixth connecting rod (14) hinged thereto; a second guide rail platform (11) hinged to the fourth connecting rod (6); a long guide rail (10) vertically fixed on the base platform (1) and movably connected to both the first guide rail platform (8) and the second guide rail platform (11); a second slider (12) bolted to the second guide rail platform (11); a seventh connecting rod (13) hinged to both the second guide rail platform (11) and the sixth connecting rod (14); an eighth connecting rod (16) hinged to the sixth connecting rod (14); a ninth connecting rod (15) hinged to the seventh connecting rod (13) and the eighth connecting rod (16); a branch plunger (17) hinged to the ninth connecting rod (15); a tenth connecting rod (18) hinged to the branch plunger (17), and a terminal slider (19) movably connected to the tenth connecting rod (18); a short guide rail (20) movably connected to the terminal slider (19) and fixed to the T-shaped tube.

[0035] The branch plungers of the two branches are respectively movably connected to the two ends of the T-shaped tube 21; the tenth connecting rods of the two branches are respectively hinged to the T-shaped tube 21.

[0036] As Figure 5 shown, the T-shaped tube 21 has a T-shaped flow channel 212 inside. The end effector 22 has an end effector plunger 221 and an end effector body 222; a section of liquid, such as pure water, is enclosed in the T-shaped flow channel 212 under the combined blocking action of the two branch plungers 17 and the end effector plunger 221. The two branch plungers 17 are arranged oppositely, and the end effector plunger 221 blocks the end of the T-shaped flow channel 212. The T-shaped tube 21 is provided with a T-shaped tube outlet 214, a first branch inlet 211 and a second branch inlet 213 which are arranged oppositely; the two branch plungers 17 respectively block the first branch inlet 211 and the second branch inlet 213; the flow area of the first branch inlet 211 is equal to the flow area of the second branch inlet 213.

[0037] The displacement magnitude of the end effector satisfies:

[0038] x A A in +x B A in =x out A out

[0039] wherein, xA is the displacement of a branched plunger 17, x B is the displacement of another branched plunger 17, x out is the displacement of the end effector plunger 221; A in is the flow area of the first branched inlet 211 or the second branched inlet 213 of the T-shaped pipe, A out is the flow area of the outlet 214 of the T-shaped pipe.

[0040] As Figure 6 shown in the schematic diagram of the movement of the end effector 22, when the two branched drive motors 2 rotate in the same direction at the same angular velocity, the end effector 22 performs a single-degree-of-freedom rotation in a plane around a remote movement center point fixed relative to the base platform coordinate system and a feeding movement along its axis; when the two branched drive motors 2 rotate in the same direction at opposite angular velocities, the end effector 22 performs a feeding movement along its axis.

Claims

1. A minimally invasive surgical robot with a mechanical-hydraulic hybrid drive, comprising: a base platform (1), a machine drive system fixed on the base platform, and an end effector (22); wherein the robot drive system includes two chain drive motors, two chains, and a T-shaped tube (21) at the ends of the two chains; the two chains form a parallel structure with the same and symmetric configurations; each chain includes: a first link (3) rotatably connected to the chain drive motor (2), a second link (5) hinged to the first link (3), a third link (4) and a fourth link (6) hinged to the second link (5), a fifth link (7) hinged to the third link (4) and the fourth link (6), a first guide rail platform (8) hinged to the fifth link (7), a first slider (9) connected to the first guide rail platform (8), and a hinged sixth link (14), a second guide rail platform (11) hinged to the fourth link (6), a long guide rail (10) movably connected to both the first guide rail platform (8) and the second guide rail platform (11), a second slider (12) connected to the second guide rail platform (11), a seventh link (13) hinged to the second guide rail platform (11) and the sixth link (14), an eighth link (16) hinged to the sixth link (14), a ninth link (15) hinged to the seventh link (13) and the eighth link (16), a chain plunger (17) hinged to the ninth link (15), a tenth link (18) hinged to the chain plunger (17), an end slider (19) movably connected to the tenth link (18), and a short guide rail (20) movably connected to the end slider (19) and fixed on the T-shaped tube; the long guide rail (10) is installed on the base platform (1) and extends upward; the chain plungers of the two chains are respectively movably connected to both ends of the T-shaped tube (21); the tenth links of the two chains are respectively hinged to the T-shaped tube (21); the T-shaped tube (21) has a T-shaped flow channel (212) inside, and the end effector (22) has an end effector plunger (221) and an end effector body (222); a section of liquid is enclosed under the combined blocking action of the chain plunger (17) and the end effector plunger (221) in the T-shaped flow channel (212), and the flow area of the first chain inlet (211) of the T-shaped tube (21) is equal to the flow area of the second chain inlet (213).

2. The minimally invasive surgical robot with a mechanical-hydraulic hybrid drive according to claim 1, characterized in that the inner closed figure formed by the hinged connection of the second link (5), the third link (4), the fourth link (6), and the fifth link (7) is a rhombus; the inner closed figure formed by the hinged connection of the sixth link (14), the seventh link (13), the eighth link (16), and the ninth link (15) is a rhombus.

3. The minimally invasive surgical robot with a mechanical-hydraulic hybrid drive according to claim 1, characterized in that The movement locus of the hinge point (161) of the eighth connecting rod (16) and the chain plunger (17) is an arc, and the radius of the arc satisfies: R＝l 1 Wherein, R is the radius of the circular arc, and l 1 is the effective rod length of the first connecting rod, that is, the distance between two circular rings on the first connecting rod.

4. A minimally invasive surgical robot with a mechanical-hydraulic hybrid drive according to claim 1, characterized in that the end effector (22) rotates with a single degree of freedom in a plane around a remote motion center point fixed relative to the base platform coordinate system and feeds along its axis direction.

5. A minimally invasive surgical robot with a mechanical-hydraulic hybrid drive according to claim 3 or 4, characterized in that the displacements of the two chain plungers (17) and the end effector plunger (221) satisfy the following expression: x A A in +x B A in =x out A out where x A is the displacement of a branched plunger (17), x B is the displacement of another branched plunger (17), x out is the displacement of the end effector plunger (221); A in is the flow area of the first branched inlet (211) or the second branched inlet (213) of the T-shaped pipe, A out is the flow area of the outlet (214) of the T-shaped pipe.

6. A control method for a minimally invasive surgical robot with a mechanical-hydraulic hybrid drive according to any one of claims 1 to 5, characterized in that when the two chain drive motors (2) rotate in the same direction with the same angular velocity, the end effector (22) rotates with a single degree of freedom in a plane around a remote motion center point fixed relative to the base platform coordinate system and feeds along its axis direction; when the two chain drive motors (2) rotate in the same direction with opposite angular velocities, the end effector (22) feeds along its axis direction.

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