Rope differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery operation

Abstract

The invention relates to a force feedback device, in particular to a rope differential driving type four-degree-of-freedom force feedback mechanism for laparoscopic surgery operation, which comprises a static platform, a working rotating shaft, a supporting shaft, a left torque motor, a detection torque motor and a movable platform, and is characterized in that the detection torque motor comprises the left torque motor and a right torque motor; a first base and a second base are fixedly installed on the static platform, the first base and the second base are rotationally connected with a first crankshaft and a second crankshaft respectively, one side of the movable platform is fixedly connected with a short shaft, the other side of the movable platform is rotationally connected with an offset shaft, and the first crankshaft is connected with the movable platform through the offset shaft. And the second crankshaft is connected with the movable platform through a short shaft. According to the invention, large-range three-direction centering rotation motion and longitudinal sliding motion can be realized, and a parallel structure is adopted, so that the mechanism is high in constraint rigidity, small in mass of moving parts and good in force sense feedback input and output effect.

Description

Technical Field

[0001] The present invention relates to a force feedback device, in particular to a rope differential drive type four-degree-of-freedom force feedback mechanism used for laparoscopic surgery. Background Art

[0002] Laparoscopic surgery has received increasing attention and research due to its many advantages. In recent years, with the development of information technology, laparoscopic surgical diagnosis and treatment techniques and equipment have made great progress. At the same time, there is a huge demand for laparoscopic surgical training, and it is required to improve the efficiency and quality of laparoscopic surgical training. Laparoscopic surgical simulators have emerged. Existing laparoscopic surgical training systems usually include force feedback devices to realistically create a virtual force sense of the surgical environment. Due to mechanical structure limitations, the existing ordinary series structure has defects such as limited actual motion range and poor dynamic performance. In order to improve the motion characteristics of the simulation system force feedback mechanism, especially to improve the motion range and dynamic response characteristics, and enhance the simulated force sense, there is an urgent need for a new four-degree-of-freedom parallel force feedback mechanism for use in the field of robotic medicine. Summary of the Invention

[0003] In order to solve the above-mentioned problems existing in the prior art, the present invention proposes a rope differential drive four-degree-of-freedom force feedback mechanism for laparoscopic surgery. Through a new topological structure, it realizes three-dimensional centering rotation and a large range of motion, meets the structural performance requirements, improves the work efficiency of medical workers, and can reduce production costs through mass production.

[0004] The technical problem to be solved by the present invention is achieved through the following technical solutions. The present invention discloses a rope differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery, including a static platform, a working shaft, a support shaft, a left torque motor, a detection torque motor and a dynamic platform. The detection torque motor includes a left torque motor and a right torque motor. The static platform is fixedly installed with a first base and a second base, and the first base and the second base are rotatably connected to a first crankshaft and a second crankshaft respectively. A short shaft is fixedly connected to one side of the dynamic platform, and an offset shaft is rotatably connected to the other side of the dynamic platform. The first crankshaft is connected to the dynamic platform through the offset shaft. The second crankshaft is connected to the moving platform through a short shaft, and the left torque motor and the right torque motor are respectively installed on the left and right sides of the upper part of the moving platform. A support shaft is slidably inserted in the center of the moving platform, and the front and rear parts of the support shaft are fixedly installed with a first pulley and a second pulley respectively. The working shaft is provided with a first bevel gear, and the bottom of the second pulley is coaxially fixedly connected to the second bevel gear. The first bevel gear and the second bevel gear are meshed for transmission. The working shaft is coaxially connected to the support shaft for rotation, and a drive rope is sleeved between the first pulley and the second pulley. The left and right sides of the drive rope are respectively driven and connected to the left torque motor and the right torque motor.

[0005] Furthermore, the first base is provided with a first rotating shaft, and the first crankshaft is rotatably connected to the first base through the first rotating shaft. The second base is provided with a second rotating shaft, and the second crankshaft is rotatably connected to the second base through the second rotating shaft. The first base and the second base are obliquely fixedly installed on both sides of the static platform and are both equipped with torque motors that are drive-connected to the second rotating shaft and the second rotating shaft.

[0006] Furthermore, the axes of the first rotating shaft and the second rotating shaft always intersect at one point and coincide with the intersection of the two rotating secondary axes of the movable platform, and the side projections of the first crankshaft and the second crankshaft are both in the shape of a hand support.

[0007] Furthermore, the offset shaft includes an offset rotation pair, the offset shaft is connected to the moving platform through the offset rotation pair, the axis of the offset rotation pair coincides with the central axis of the moving platform, and the offset rotation pair is used to form an angle change between the short shaft and the offset shaft during movement.

[0008] Furthermore, a limiting spline for limiting circumferential rotation is provided in the middle of the support shaft, and a spline groove is correspondingly provided at the center of the moving platform.

[0009] Furthermore, the ends of the left torque motor and the right torque motor are both provided with contact pulleys, and the left torque motor and the right torque motor both realize contact transmission with the drive rope through the contact pulleys.

[0010] Furthermore, the four degrees of freedom of the working shaft can be reflected by the detection torque motor. The detection torque motor is provided with a motor encoder. The motor encoder is provided with a position reading module and a data calculation module to achieve real-time force feedback and mechanism posture monitoring.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] (1) The present invention can realize a wide range of three-way centered rotational motion and longitudinal sliding motion. The parallel structure is used to make the mechanism constraint rigidity high, the moving parts have a small mass, and the force feedback input and output effects are good;

[0013] (2) The mechanism of the present invention has a simple and direct motion form, is easy to implement feedback and control processes, has high reliability, and has a large range of motion for operation, thereby increasing the scope of application;

[0014] (3) The present invention utilizes a simple and compact structure combined with the characteristics of rope differential motion to effectively reduce the inertia of the end effector and improve dynamic performance. In addition, the rope drive occupies a small working space, the rope arrangement is flexible, and it is easy to manufacture and assemble, thereby reducing the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention in a general posture;

[0016] Figure 2 Schematic diagram of the structure of the present invention in the first motion posture;

[0017] Figure 3 Schematic diagram of the structure of the second motion posture of the present invention;

[0018] 1-static platform, 2-first base, 3-first rotating shaft, 4-first crankshaft, 5-working rotating shaft, 6-first bevel gear, 7-second bevel gear, 8-first pulley, 9-second crankshaft, 10-second rotating shaft, 11-second base, 12-support shaft, 13-pulley fixing shaft, 14-short shaft, 15-left torque motor, 16-second pulley, 17-right torque motor, 18-drive rope, 19-moving platform, 20-offset shaft. DETAILED DESCRIPTION

[0019] The technology of the present invention is described in detail below with reference to the accompanying drawings:

[0020] See also Figure 1-3 The present invention discloses a cable-differential-driven four-degree-of-freedom force feedback mechanism for laparoscopic surgery, comprising a static platform 1, a working shaft 5, a support shaft 12, a left torque motor 15, a right torque motor 17, and a dynamic platform 19. The static platform 1 is fixedly placed on a table, and the main parts of the mechanism are mounted on the static platform 1. A first base 2 and a second base 11 are mounted on the static platform 1, respectively.

[0021] The first rotating shaft 3 and the second rotating shaft 10 are respectively mounted on the first base 2 and the second base 11. Limited by the installation conditions of the first base 2 and the second base 11, the axes of the first rotating shaft 3 and the second rotating shaft 10 always intersect at one point, which is the rotation center of the moving platform 19. The rotational movement of the first rotating shaft 3 and the second rotating shaft 10 can be monitored and driven by a torque motor respectively. For the sake of simplicity, the torque motor can realize subsequent force feedback. The first crankshaft 4, the offset shaft 20, the second crankshaft 9 and the short shaft 14 respectively constitute two transmission branches. The first crankshaft 4 and the offset shaft 20 are directly connected by a rotating pair, and the second crankshaft 9 and the short shaft 14 are also directly connected by a rotating pair. The intersection of the two rotating pair axes coincides with the intersection of the two rotating shaft axes.

[0022] The movable platform 19 includes a left torque motor 15, a right torque motor 17 and a support shaft 12. One side of the movable platform 19 is fixedly connected to the short shaft 14, and the other side is connected to the offset shaft 20 by a revolving pair. The axis of the revolving pair coincides with the central axis of the movable platform 19. The revolving pair can realize the change of the angle between the short shaft 14 and the offset shaft 20 during the movement to meet the motion characteristics of the mechanism. The left torque motor 15 and the right torque motor 17 are respectively fixedly connected to the left and right sides of the movable platform 19. The left torque motor 15 and the right torque motor 17 are each fixed with a wire pulley.

[0023] The support shaft 12 is disposed within the movable platform 19, with its axis coinciding with the centerline of the movable platform 19, and the two are splined. A second sheave 16 and a first sheave 8 are fixedly mounted at each end of the support shaft 12 via sheave fixing shafts 13. The ends of the support shaft 12 are connected to the working shaft 5 via a revolving pair. The sheaves on the left and right torque motors 15 and 17 are connected to the second sheave 16 and the first sheave 8 via drive ropes 18. The axial sliding motion of the support shaft 12 is synchronously transmitted to the rotation of the left and right torque motors 15 and 17 via the ropes. The second bevel gear 7 is coaxially fixedly connected to the second sheave 16, allowing them to rotate synchronously. The first bevel gear 6 is fixedly connected to the working shaft 5, meshing with the second bevel gear 7. The rotation of the working shaft 5 is synchronously transmitted to the left and right torque motors 15 and 17 via the first bevel gear 6, the second bevel gear 7, and the second sheave 16.

[0024] Using the differential principle, the motion of the working shaft 5 can be determined: when the working shaft 5 only performs circumferential rotation, the left torque motor 15 and the right torque motor 17 rotate at the same speed and in the same direction, and the rotational direction is the same as that of the working shaft 5; when the working shaft 5 only performs axial sliding motion, the left torque motor 15 and the right torque motor 17 rotate at the same speed and in opposite directions, and their respective rotational directions are related to the direction of the axial sliding motion of the working shaft 5; when the working shaft 5 performs both circumferential rotation and axial sliding motion, the left torque motor 15 and the right torque motor 17 rotate at different speeds (including different directions). That is, in the present invention, both the circumferential rotation and axial sliding motion of the working shaft 5 can be transmitted and converted into the relative rotation parameters of the left torque motor 15 and the right torque motor 17. Specifically, the axial sliding motion of the support shaft 12 relative to the moving platform 19 is reflected by the bilateral rotation of the left and right torque motors 15 and 17 by the drive rope 18, and is fed back as synchronous rotation sub-motion data of the drive rope 18 through motor detection. Meanwhile, the rotation of the working shaft 5 relative to the support shaft 12 is reflected by the rotation of the left and right torque motors 15 and 17 by the two rope pulleys driven by the bevel gears, and is fed back as unidirectional rotation sub-motion data of the drive rope 18 through motor detection. The motion parameters detected by the left and right torque motors 15 and 17 are the superposition of the two sub-motions, and the rope differential transmission data of the two sub-motions is obtained through certain data calculations. Simultaneously, the two-degree-of-freedom rotation of the moving platform 19 is converted by the two branch chains into rotation of the first and second rotating shafts 3 and 10, and the rotation data is directly fed back and detected by the torque motors connected to each.

[0025] During actual operation, the operator manually operates the operator on the movable platform 19 (located on the working shaft 5). On the one hand, the movable platform 19 rotates, driving the two branches (the first crankshaft 4, the offset shaft 20 and the second crankshaft 9, the short shaft 14) to rotate, and then driving the first rotating shaft 3 and the second rotating shaft 10 to rotate, and finally mapping the two-degree-of-freedom posture motion of the movable platform 19 to the rotation of the corresponding torque motor. On the other hand, the working shaft 5 (operator) is dragged by the operator to complete circumferential rotation motion and axial sliding motion, and this motion is converted into the mutually related rotational motion of the left torque motor 15 and the right torque motor 17 through the transmission of the rope. All four degrees of freedom of the working shaft 5 can be reflected on the four torque motors. By reading the position of the motor encoder and combining it with the program, force feedback is realized to complete the work.

[0026] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A cable-differential-driven four-degree-of-freedom force feedback mechanism for laparoscopic surgery, comprising a static platform, a working shaft, a support shaft, a left-side torque motor, a detection torque motor, and a dynamic platform, characterized by: The detection torque motor includes a left torque motor and a right torque motor, the static platform is fixedly installed with a first base and a second base, the first base and the second base are rotatably connected to the first crankshaft and the second crankshaft respectively, one side of the moving platform is fixedly connected to a short shaft, and the other side of the moving platform is rotatably connected to the offset shaft, the first crankshaft is connected to the moving platform through the offset shaft, and the second crankshaft is connected to the moving platform through the short shaft, the left torque motor and the right torque motor are respectively installed on the left and right sides of the upper part of the moving platform, the center of the moving platform is slidably inserted with a support shaft, the front and rear parts of the support shaft are respectively fixedly installed with a first pulley and a second pulley, the working rotating shaft is provided with a first bevel gear, and the bottom of the second pulley is coaxially fixedly connected to the second bevel gear, the first bevel gear and the second bevel gear are meshed for transmission, the working rotating shaft is coaxially rotatably connected to the support shaft, a driving rope is sleeved between the first pulley and the second pulley, and the left and right sides of the driving rope are respectively connected to the left torque motor and the right torque motor.

2. The cable differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery according to claim 1, characterized in that: The first base is provided with a first rotating shaft, and the first crankshaft is rotatably connected to the first base through the first rotating shaft. The second base is provided with a second rotating shaft, and the second crankshaft is rotatably connected to the second base through the second rotating shaft. The first base and the second base are fixedly installed obliquely on both sides of the static platform and are both equipped with torque motors that are drive-connected to the second rotating shaft and the second rotating shaft.

3. The cable differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery according to claim 2, characterized in that: The axes of the first rotating shaft and the second rotating shaft always intersect at one point and coincide with the intersection of the two rotating secondary axes of the moving platform. The side projections of the first crankshaft and the second crankshaft are both in the shape of a hand support.

4. The cable differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery according to claim 1, characterized in that: The offset shaft includes an offset rotating pair, the offset shaft is connected to the moving platform through the offset rotating pair, the axis of the offset rotating pair coincides with the central axis of the moving platform, and the offset rotating pair is used to form an angle change between the short shaft and the offset shaft during movement.

5. The cable differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery according to claim 1, characterized in that: A limiting spline for limiting circumferential rotation is provided in the middle of the support shaft, and a spline groove is correspondingly provided at the center of the moving platform.

6. The cable differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery according to claim 1, characterized in that: The ends of the left torque motor and the right torque motor are both provided with contact pulleys, and the left torque motor and the right torque motor both realize contact transmission with the driving rope through the contact pulleys.

7. The cable differential drive type four-degree-of-freedom force feedback mechanism for laparoscopic surgery according to claim 1, characterized in that: The four degrees of freedom of the working shaft can be reflected by the detection torque motor. The detection torque motor is provided with a motor encoder. The motor encoder is provided with a position reading module and a data calculation module to achieve real-time force feedback and mechanism posture monitoring.

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