RU223353U1 - Longitudinal movement device for a robotic catheter - Google Patents

Abstract

The utility model relates to the field of robotic surgery for endovascular operations, more specifically to robotic catheter assemblies that provide longitudinal movement of surgical catheters or guides. A longitudinal movement device for a robotic catheter, including moving platforms (37+38) with a docking interface (7) for removable modules (3, 4, 40, 41), a motor (10), a screw drive (11+13) and a guide rail ( 12), installed in the end supports of the housing (16+20), (17+21), characterized in that the platforms move dependently and independently of each other using one drive motor (10), transmitting torque to a screw drive from one screw (11) and nuts (13), which, when the screw (11) rotates, in case of fixation in the tangential direction by the locking mechanism (26+27+28+29) move along the axis of the screw, moving the platforms along with them, and in case of disconnection locking mechanism (26+27+28+29) rotate together with the screw (11), without moving in the axial direction, keeping the platforms (37+38) in one place. The technical result of the claimed utility model of a longitudinal movement device for a robotic catheter is an increase in the degrees of freedom of the moving platforms when using a single drive based on a screw drive.

Description

Field of technology

The present description relates to the field of robotic surgery for endovascular operations. More specifically, the description relates to robotic catheter assemblies that provide longitudinal movement of surgical catheters or guidewires.

Technical problem

Robotic catheters are used for endovascular operations. They replace the surgeon in the operating room, while the surgeon controls the robotic system remotely using a remote control. Robotic catheters perform a limited set of actions: they move the guidewire and the catheter with the instrument (stent or balloon) in the axial direction or rotate it.

Currently, robotic catheters are developing in two directions: some move surgical instruments by rolling them with honey rollers, others move the catheter by moving the platform in which the surgical instrument is fixed. The first version of the system is designed exclusively for stenting and balloon angioplasty, while the second version of the system may be more universal; for example, it is used for RFA operations. Embolization of aneurysms with microcoils, cutting or rotational atherectomy, placement of traps for excised atherosclerotic plaques, and thrombectomy are all currently performed manually and require varying numbers of simultaneous instruments. The number of moving platforms, the free passage distance, their kinematic and precision characteristics determine what types of surgical interventions and what stages can be performed by a specific robotic system.

Analogues

From the existing level of technology, a device for moving a robotic catheter is known, which is made of a screw gear, including 1 motor, 1 screw, 1 nut and a platform attached to it (CN116211476A, publ. 06/06/2023). The disadvantages of this technical solution are the movement of only one platform on which surgical instruments can be placed.

From the existing level of technology, a device for moving a robotic catheter is known, which is made of a duplicated assembly unit of a screw drive, located coaxially, sequentially to each other, having in total 2 platforms, 2 motors, 2 screws and 2 nuts (A Remote-Controlled Robotic System with Safety Protection Strategy Based on Force-Sensing and Bending Feedback for Transcatheter Arterial Chemoembolization, published 08/25/2022). The disadvantages of this technical solution are the need to include two power motors in the system, which require control and high supply currents, and an increase in the dimensions of the structure.

From the existing level of technology, a device for moving a robotic catheter is known, which contains 4 motors and 4 moving platforms using cables and pulleys (Design and Performance Evaluation of Real-time Endovascular Interventional Surgical Robotic System with High Accuracy, published October 2018). Such a device has smaller dimensions and greater mobility compared to devices based on ball screws, however, a device operating on separate motors and cables shows worse indicators of the accuracy of platform movement, for example, the accuracy of the mutual speed of the platforms is 0.62 cm/s at peak load.

The closest to the claimed technical solution is a device for moving a robotic catheter, consisting of one ball screw and 4 ball screws installed on it, and, as a consequence, an unlimited number of platforms (EP4245240 (A2), published 09/20/2023). The disadvantages of this technical solution are the need to install a power motor on each moving platform for movement, which requires separate power supplies and drivers for control, which increases the dimensions of the structure.

Disclosure of the essence of the utility model

Technical result of the utility model

The technical result of the claimed utility model of a device for longitudinal movements for a robotic catheter is an increase in the degrees of freedom of the moving platforms when using a single drive based on a screw drive.

Essence of a utility model

This problem is solved due to the fact that the claimed device for longitudinal movements for a robotic catheter, including movable platforms with a universal docking interface for removable modules, a motor, a screw gear and a guide rail installed in the end supports of the housing, characterized in that the movement is dependent and independent of each other platforms from each other are carried out using one drive motor transmitting torque to a screw gear consisting of one screw and nuts, which, when the screw rotates, in the case of fixation in the tangential direction by the locking mechanism, move along the axis of the screw, moving the platforms along with them, and in the case of disabling the locking mechanism mechanisms - rotate together with the screw, without moving in the axial direction, keeping the platforms in one place.

Perhaps the longitudinal movement device for a robotic catheter is different in that the locking mechanism on the movable platform, when turned on, with its protruding part rests against the part attached to the screw drive nut and blocks its rotation.

Perhaps the longitudinal movement device for a robotic catheter differs in that the driver of the locking mechanism is based on a solenoid that moves a part with a protruding part.

Perhaps the longitudinal movement device for a robotic catheter differs in that the driver of the locking mechanism is based on a servo drive, the rotation of which moves the part with the protruding part.

Perhaps the longitudinal movement device for a robotic catheter is different in that the part attached to the screw gear nut has a toothed surface, into the grooves of which the part with the protruding part of the locking mechanism fits, stopping its rotation.

Perhaps the longitudinal movement device for a robotic catheter is different in that the part attached to the screw nut has a high friction surface against which the protruding part rests, preventing it from rotating.

Perhaps the longitudinal movement device for a robotic catheter differs in that the platforms and the screw-nut locking mechanism have the ability to be uncoupled, in which the platforms can be moved along the guide manually, regardless of the operation of the engine and the high gear ratio of the screw drive.

Perhaps the device for longitudinal movements for a robotic catheter is different in that each end support is made of two components: one holds the bearing for fixing the screw of the screw drive, the second holds the guide - the end supports are made with the possibility of sliding, and in the “extended” position the distance between the helical gear screw and the guide is increased relative to the “shifted” one, which leads to a break in the mechanical connection between the moving platform and the helical gear nut and allows the platforms to be moved manually.

Drawings and their descriptions

Figure 1 - Isometric view of the robotic catheter system, which consists of a longitudinal movement device, a control module and rotation modules for the catheter and guidewire.

Fig. 2 - Isometric view of the longitudinal movement device for a robotic catheter (a) and with the housing removed (b).

Fig. 3 - Perspective side view of the longitudinal movement device for a robotic catheter (body removed) in working condition (end supports moved) (a) and in a state of manual movement (end supports extended) (b).

Fig. 4 - Perspective view of the mechanism for fixing the longitudinal movement device for a robotic catheter, allowing the platforms to be moved independently of each other (a), midsection (b) and isometric view (c).

Fig. 5 - Schematic representation of the longitudinal movement device for a robotic catheter (a) and mathematical formulas describing the equation of motion (b)

Fig. 6 - Scheme of platform movement when measuring accuracy (a). Graphs of the results of measuring the accuracy of movement (b) and the inter-platform distance when simultaneously moving two platforms in shuttle mode (c).

Fig. 7 - Isometric view of the robotic catheter system in alternative configurations, with one movable platform for ultrasound vein obliteration (a) and three movable platforms for rotational atherectomy (b).

Fig. 8 - Block diagram of a tree of various types of endovascular operations.

Fig. 9 - Perspective top view of the universal interface for connecting removable units, version with fastening (latch) (a) and fastening with a flexible mechanism (b).

Fig. 10 – Top perspective view of the control panel of the robotic catheter.

Implementation of a utility model (detailed description)

Description of structure and drawings

The longitudinal movement device for the robotic catheter 1 (Fig. 1) is presented in an assembled state with the rotation and feedback modules of the catheter 4, the rotation and feedback module of the conductor 3, the control panel 2, together the blocks represent a fully functioning robotic catheter. The robotic catheter is positioned along the lying patient, the mount for the Y-connector and introducer 31 is located directly next to the puncture site. In the presented configuration, a catheter 5 and a guide 6 are installed in the robotic catheter and are fixed with their proximal (near) ends in rotation blocks 4 and 3, respectively, and their distal ends extend beyond the robotic catheter, that is, they are inserted into the patient. Telescopic tubes 30 are installed to prevent excessive bending of surgical instruments between the moving and stationary parts of the robotic catheter.

In an alternative configuration, in place of the removable blocks 3 or 4, a block for ultrasonic vein obliteration 40 can be installed, in which the ultrasonic instrument 39 of FIG. 7 or blocks for rotational athetectomy, including a block for a guide 3, a block for a drill-catheter 4, a block for trapping excised tissue 41. Endovascular instruments 5, 6, 42 are shown schematically. This useful model of a longitudinal movement device is designed with universal connectors 7, on which it is possible to install blocks for controlling or fixing endovascular instruments for various medical interventions shown in Fig. 8: cylinder angioplasty, stenting, aspiration or rotational thrombectomy, platectomy with a stall with retriever, selective thrombolysis, cutting or rotational aterectomy, laser aterctomy, treatment of calcified atherosclerotic plaques with a cutting cylinder, embolization of aneurysm with spirals or adhesive composition, diagnostic endov Angiography, carboxography, ultrasonic intravascular interventions imaging, optical coherence tomography; minimally invasive heart surgery RFA and others.

The longitudinal movement device for the robotic catheter 1 is shown in Fig. 2a separately from the other blocks in a configuration with two movable platforms; in Fig. 2b it is shown with the housing elements removed. Further description of the device operation will be presented using this configuration as an example. The moving platforms (37+38) have power and signal transmission buses laid through cable channels 18. Universal connectors 7 have contacts for transmitting power 45 and exchanging data 46 with removable units, the configurations of which are shown in Figures 9a and 9b. The connection interfaces have a connection mechanism based on the elastic properties of plastic.

In fig. 3a shows a side view of a longitudinal movement device for a robotic catheter, based on a ball screw mechanism consisting of a screw 11 and nuts 13. The screw 11 rotates using a power motor 10, and is secured at both ends through ball bearings installed in supports 16 and 17. The motor is controlled by a microcontroller and driver 19. Profile 15 is used to fix the supports 16 and 17. The guide rail 12 is fixed in the support elements 20 and 21. The carriages 14 move along the guide rail 12, which carry the entire useful mass of the movable platforms and the removable blocks installed on them.

The structure of the moving platforms in one of the configurations is shown in Figure 4 and consists of two detachable assemblies: the carriage assembly 38 and the nut assembly 37. The nut assembly consists of a ball screw nut 13, a thrust bearing 24, a bearing fastener 25 and a part of the locking mechanism with a winged (gear) surface 26. The carriage assembly consists of a carriage 14, a connection interface for a removable unit 7, a housing part 23 in which a servo drive 29 is installed, which is part of the locking mechanism. A lever 28 is attached to the servo drive shaft so that when the lever is turned, the valve 27 moves along its axis. The housing member 23 has a groove into which the bearing 24 fits so that the entire nut assembly 37 cannot move axially relative to the carriage assembly 38, but can freely rotate about its axis relative to the carriage assembly 38 while the locking mechanism is in the OFF position. In the ON position of the locking mechanism, the servo drive 29 moves the pin 27 so that its end fits into the groove of the cover part 26, which prohibits the rotation of the nut assembly 37.

The control panel 2 of the longitudinal movement device for the robotic catheter is shown in Fig. 10. It can be used as a primary control source or as an alternative to computer interface control. As control elements, the remote control 2 includes one device for inputting speed or distance of movement in the form of a joystick or slider 33 and buttons for entering the state of the locking mechanism 35, illuminated by LEDs when activated. Such controls are justified by the design of the device for longitudinal movements of the robotic catheter, that is, the ability to set only the same speed when moving different platforms simultaneously. Power button 32 of the control panel, keyboard 36 and liquid crystal display 34

Functional description.

The independent movement of the platforms is ensured by rotating the screw 11 and turning on and off the locking mechanisms of the movable platforms. When the engine 10 is turned off, all platforms are at rest in place. When the engine 10 is turned on and the locking mechanisms are turned off, that is, when the pin 27 does not block the rotation of the wing part 26, the ball screw 11 together with the ball screw nut assemblies 37 on it rotate around its axis, while the platforms rest in one place. Free rotation of the carriage assembly 38 relative to the nut assembly 37 is possible due to their connection by means of a bearing 24. When the locking mechanism is turned on on one or more movable platforms, the pin 27 stands between the teeth of the wing part 26, stopping its rotation, as a result of which the entire nut assembly 37 stops rotating, including, directly, the ball screw nut 13. With the screw 11 rotating and the nut 13 fixed in the tangential position, the nut 13 begins to move along the screw 11 in the axial direction and push the carriage assembly 38 through the bearing 24 installed in the groove of the part 23. Thus, the entire movable the platform moves depending on whether its locking mechanism is turned on or off.

The presented mechanism for the device of longitudinal movements for a robotic catheter does not impose restrictions on the number of mobile platforms installed and moved simultaneously or alternately (37+38).

Since the utility model of a longitudinal movement device for a robotic catheter is used in surgery, there are requirements in the event of a failure to be able to move the catheter manually to safely terminate the operation or to continue it manually. Free movement of platforms when the engine is turned off when using ball screws or screw gears is in most cases impossible due to the high gear ratio. In the presented solution, the provided transition to the manual mode of moving the platforms is independent of the operation of the engine, which is shown in Fig. 3b in one of the possible configurations. The front support 16, 20 and the rear support 17, 21 each consist of two parts. Parts 16 and 17 hold the screw 11, on which the nut assemblies 37 are located, and parts 20 and 21 hold the guide 12, on which the carriage assemblies 38 are located. Handles 9 and 8 are attached to parts 20 and 21, respectively, when turning and moving the levers of the handles 8 and 9, supports 16 and 20, as well as 17 and 21 move apart, which leads to an increase in the distance between the screw 11 and the guide 12, as a result of which the bearing 24 of the nut assembly 37 comes out of the groove of the carriage assembly part 23 and no longer transmits translational motion from the nut to the carriage, and also does not interfere with the free movement (movement by hand) of the movable platforms along the guide 12. When moving the levers of the handles 8 and 9 to their original position, the movement of the platforms can continue by means of the engine.

Alternative configuration

Alternative configurations of longitudinal movement device elements for a robotic catheter are shown in the drawings.

Breaking the mechanical connection between the nut 13 and the carriage 14 can occur without moving the screw 11 relative to the guide 12, but through a docking mechanism, due to which the carriage 14 is released relative to the part 23 to carry out longitudinal movement along the guide 12, regardless of the operation of the engine 10.

The movement of the pin 27 in the locking mechanism can be carried out by the servo drive 29 not due to the lever 28, but due to the rotation of the gear on the motor shaft with counter teeth on the pin 27. The movement of the pin 27 in the axial direction can be carried out not by the servo drive 29, but by a solenoid or a screw gear. The pin 27 can block the rotation of the nut assembly 37 not by abutting the wing piece 26, but by abutting a piece with a high friction surface, such as a rubber coating. The locking mechanism may use a disc-shoe mechanism instead of pin 27, similar to a car brake.

Instead of assembling the nut 37 and the locking mechanism, a locking system of claws can be used, when activated, it grabs directly onto the rotating screw 11, eliminating the mechanical transmission intermediary in the form of a nut 13.

Screw 11 can be either for a ball screw drive or just a screw drive.

Achievability of technical result

The results of measuring the accuracy of moving the robotic catheter platforms are presented in Fig. 6.

In fig. Figure 6b shows the measurement results of the longitudinal movement device and their root-mean-square spread when identifying sources of interference of the longitudinal movement device separately: stepper motor, ball screw, original locking mechanism. 6 series of 15 repetitions were carried out, carried out according to the protocol presented in Fig. 6a: 1 - Continuous movement of the platform by 500 mm (2 - by 100 mm); 3 - Move the platform by 500 mm (4 - by 100 mm) with stops every 50 mm (4 - every 10 mm); 5 - Move the platform by 500 mm (6 by 100 mm) with stops every 50 mm (6 - 10 mm). During the stop, the locking mechanism was deactivated, the screw was turned to a random angle, then the locking mechanism was activated and movement continued. Analysis of the accuracy of movements showed that a single random error of the stepper motor is 0.005 mm, the screw-nut assembly unit is 0.2 mm/m of the original locking mechanism is 0.05 mm, thus a single movement of 1 m is made with a root-mean-square error of 0.255 mm.

In fig. 6c shows a graph of the results of tests in which the inter-platform distance was measured while simultaneously moving two platforms in shuttle mode 7 times by 500 mm. The accumulated root-mean-square error for the 3.5 m traveled was 0.03 mm. This result means extremely small divergence of platforms during simultaneous movement.

The mathematical formulas are shown in Fig. 5b to calculate the required torque of the power motor Tmt for simultaneous movement from 0 to 10 platforms with given parameters of speed, payloads, accelerations, friction forces, and screw drive parameters. Some of the letter designations are indicated in FIG. 5a.

Table 1 – Designations in the equation of motion of the block of longitudinal movements

Ball screw weight m _sс 1.6 kg Ball screw nut weight _mnt 0.165 kg Mass platform (or slider) m _pl 0.4 kg Mass of actual load (then this is payload) m _al 5 kg Travel speed dx/dt m/s Acceleration of movement d ^∧ 2x/dt ^∧ 2 m/s ^∧ 2 Coef. friction in supports _μsp 0.003 Coef. friction nut _μnt 0.002 Coef. platform bearing friction μ _br 0.002 Coef. platform friction μ _pl 0.004 Number of fixed platforms N 0 .. 10 Number of moving platforms M 0 .. 10 Ball screw pitch p 0.005 m Bearing radius r _br 0.0125 m Ball screw radius r _sc 0.008 m Radius of support bearings r _sp 0.005 m Ball screw transmission efficiency h 0.90 Force required to move the platform F _fpl Formula 1 Total moved mass of one platform m Formula 4 Ball screw nut preload force F _pr 85 H*mm Axial force on nut (load) _Fl Formula 5 Force applied by the tool F _tl 50 N Radial load on supports F _rad Formula 6 Friction moment on the platform bearing _Tfbr Formula 2 Frictional moment on the ball screw nut _Tfnt Formula 3 Friction moment on supports _Tfsp Formula 7 Calculated motor torque _Tmt Formula 11 Engine damping rate B 0.01 Motor inertia moment _Jmt 0.3 kg/cm^2 Ball screw nut moment of inertia _Jnt Formula 9 Ball screw moment of inertia _Jsc Formula 8 Coupling moment of inertia J _sx 0.02 kg/cm^2 Total moment of inertia of rotating elements J Formula 10

Conclusion

The developed utility model of a longitudinal movement device for a robotic catheter was tested in a configuration with three movable platforms. From testing the test model, a conclusion was drawn about the operability of the design and the achievement of a technical result with its help. That is, the device, using one power motor, provides a number of degrees of freedom of movement equal to the number of movable platforms installed on it. Moreover, the design allows the platforms to be moved manually independently of each other.

Claims (8)

1. A device for longitudinal movements for a robotic catheter, including movable platforms with a docking interface for removable modules, a motor, a screw gear and a guide rail installed in the end supports of the housing, characterized in that the platforms move dependently and independently of each other using one drive an engine transmitting torque to a screw gear consisting of one screw and nuts, which, when the screw rotates, if fixed in the tangential direction by the locking mechanism, move along the axis of the screw, moving the platforms along with them, and if the locking mechanism is turned off, they rotate with the screw without moving axially, keeping the platforms in one place. 2. A device for longitudinal movements for a robotic catheter according to claim 1, characterized in that the locking mechanism on the movable platform, when turned on, with its protruding part rests against the part attached to the screw drive nut and blocks its rotation. 3. A device for longitudinal movements for a robotic catheter according to claim 2, characterized in that the driver of the locking mechanism is based on a solenoid that moves the part with the protruding part. 4. A device for longitudinal movements for a robotic catheter according to claim 2, characterized in that the driver of the locking mechanism is based on a servo drive, the rotation of the rotor of which moves the part with the protruding part. 5. A device for longitudinal movements for a robotic catheter according to claim 2, characterized in that the part attached to the screw gear nut has a toothed surface, into the grooves of which the part with the protruding part of the locking mechanism fits, stopping its rotation. 6. A device for longitudinal movements for a robotic catheter according to claim 2, characterized in that the part attached to the screw gear nut has a surface against which the part with the protruding part rests, preventing its rotation 7. A device for longitudinal movements for a robotic catheter according to claim 1, characterized in that the platforms and the screw-nut locking mechanism have the ability to be uncoupled, in which the platforms can be moved along the guide manually, regardless of the operation of the engine and the gear ratio of the screw drive. 8. A device for longitudinal movements for a robotic catheter according to claim 7, characterized in that each end support is made of two components: one holds the bearing for fixing the screw of the screw drive, the second holds the guide, the end supports are made with the ability to expand, and in the “extended” " position, the distance between the screw gear and the guide is increased relative to the "shifted" one, which leads to a break in the mechanical connection between the movable platform and the screw gear nut, that is, to uncoupling, and allows you to move the platforms manually.