The invention relates to a robotic manipulator for the remote manoeuvring, in the human cardiovascular system, of temporary catheters for electrophysiology procedures, these catheters being provided with controls for deflection of the distal end and therefore being described as “steerable”. More specifically, the invention relates to constructional improvements to the robotic manipulator described in Italian patent application BO2005A-799 in the name of the present applicant, to which the most general reference will be made, and which describes an apparatus for this purpose, of the type shown schematically in the attached FIG. 1, which uses an introducer A which is also protected by Italian patent application BO2005A-798 in the name of the present applicant, and which comprises a said robotic manipulator B to be placed near the patient P, in a relatively fixed and predetermined position, for supporting and guiding the catheter C by its handle D, the manipulator comprising telescopic stiffening means E, with which the portion of said catheter which lies outside the patient's body, and which lies between said handle and said introducer and is gripped by said telescopic means E, is kept axially aligned with said handle and essentially rigid, such that it cannot bend as a result of the buckling force when the catheter is manoeuvred by the robotic manipulator via the handle. The robotic manipulator B is designed to support the handle D and the slider F or other suitable means for deflecting the distal end of the catheter and is remotely controllable by an operator in a remote position who is shielded from the ionizing radiation emitted by the system which displays the navigation of said catheter in the human cardiovascular system. For operating the catheter, the robotic manipulator B must be capable of subjecting the catheter, by supporting its handle, to advance and retraction movements, to axial rotation in both directions, and to the necessary steering movements to enable the tip of the catheter to be steered through the twists and turns of the cardiovascular system of the patient P and to reach a predetermined point of this system, in a controlled, safe and repeatable way.
The robotic manipulator described in the patent application to which reference is made comprises a body B1 which is associated, by means of a rectilinear guide and sliding block unit G having a screw and nut actuator and a geared motor and encoder, with the end of a hinged and/or jointed arm H, having rapidly and easily connectable and disconnectable hinges and/or joints, by means of which the guide of said system G can be fixed with the desired orientation for a desired position of the bed L and/or other structure supporting the patient. The body B1 of the manipulator carries at its end and in axial alignment a shaft which can be rotated in a precise way by means of a geared motor with encoder positioned in the body B1, and an arm B2 with an L-shaped lateral profile is fixed to this shaft by its base so that it projects therefrom, this arm forming a longitudinal extension of the said body of the manipulator. On the arm B2, means M are provided to fix the handle D of the catheter longitudinally, and gripping means N are provided to act on the slider F, push button or other means of this handle which is connected to the catheter steering means, and said gripping means N are connected to an actuator, of the rectilinear motion type for example, with a corresponding geared motor and encoder, housed inside B2. The means which support the catheter handle are mounted on a guide and sliding block unit connected to a load sensor which generates an electrical signal proportional to the resistance encountered by the handle in the axial movement of the catheter, for the purpose of detecting whether or not the resistance encountered by the catheter is acceptable during the movements imparted by the operator's remote control actions. All the electrical and electronic components in the terminal arm of the manipulator which supports the catheter handle are connected to a terminal block fixed in the body B1 of the manipulator, by means of flexible electrical cables which pass through curved slots which have a substantial angular amplitude and which are formed in the facing bases of the arm B2 and the body B1.
Tests of a manipulator constructed in this way have revealed the following limitations.
A first limitation is due to the limited and difficult axial rotation of the arm B2 of the manipulator, caused by said curved slots, and the invention proposes to overcome this limitation by using a rotary collector positioned axially in the manipulator body. A second limitation arises from the considerable length of the manipulator when in the maximally extended state, this being due to the fact that the catheter advance and retraction means G are located on the body B1 of the manipulator of FIG. 1. The invention proposes to overcome this limitation by providing the catheter advance and retraction means on the arm B2 which also supports the catheter handle and has a length related to that of the handle, and which is therefore adapted for this use. In this way the manipulator body can be made with limited dimensions.
Another limitation of the known solution arises from the lower degree of safety that might be encountered as a result of having the movement encoders connected directly and solely to the electric motors of the three actuators used. The invention proposes to overcome this limitation by using supplementary encoders to detect the motion of the terminal part of the kinematic chain driven by each of said motors.
These and other characteristics of the invention, and the advantages derived therefrom, are illustrated more fully in the following description which refers to the figures on the three attached sheets of drawing, in which, in addition to FIG. 1 which has already been discussed:
FIG. 2 is a lateral view, with parts in longitudinal section, of the new robotic manipulator, with its components positioned in the start of cycle condition;
FIG. 3 is a plan view from above of the manipulator with the catheter handle support arm, with the covering elements removed in order to reveal the internal components, and without the means which acts on the catheter steering controller;
FIGS. 4, 5 and 6 show three details of the construction of the manipulator, taken, respectively, along the section lines IV-IV, V-V and VI-VI of the preceding FIGS. 2 and 3.
FIGS. 2, 3 and 4 show that the manipulator comprises a boxlike body 1, of cylindrical shape for example, with a round cross section, having a base 101 of considerable thickness and having a lateral appendage 201 for connection to the hinged and/or jointed arm for supporting the manipulator in operation, as indicated for example by H in FIG. 1, the body being closed at its rear with an end plate 301 which is removable for access to the internal parts of the body 1, and having apertures which are not shown for the passage of the electrical power supply and control cables of the manipulator. The end plate 101 is provided with an axial hole 2 in which is rotatably housed, by means of bearings and/or other suitable means 3, a hollow shaft 4 which has an external flange 104 and which has a portion, projecting into the body 1, on which is keyed a ring gear 5 which engages with a pinion 6 keyed on the axle of a reversible geared motor unit 7 with an encoder, fixed by flanges to a support 8 fixed to the end plate 101, said ring gear 5 also engaging with a pinion 9 keyed on the axle of an encoder 10 fixed to the same end plate 101 by means of a support 11. The encoder 10 generates an electrical signal which is processed in combination with that received from the encoder of the drive unit 7, to detect any malfunction of the kinematic chain in which it is fitted, even if the encoder of the unit 7 detects normal operation, for example if there is any slippage of one of the two components of the gearing 5, 9. In FIG. 4, the number 37 indicates a microswitch which can read a projecting or recessed part of the hollow shaft 4, close to the ring gear 5, and which provides the “zero” reference for the computing system with which said safety encoder 10 and the encoder of the drive unit 7 are associated.
The rotating element 112 of a rotary collector 12 is fitted partially into the end of the hollow shaft 4 which projects into the body 1 (FIG. 2), in a substantially coaxial arrangement, to enable fixed cables (not shown) which enter the body 1 to be connected to all the power supply and control circuits of the electrical and electronic components of the manipulator located on the arm of the manipulator, which is fixed to the flange 104 and which supports the catheter handle as described below.
The flange 104 of the hollow shaft 4 (FIGS. 2 and 3) is fixed to the base 113 of the L-shaped arm 13, which is similar in shape and dimensions to the arm B2 of FIG. 1 but differs from the latter in that it is essentially composed of two parts fitted telescopically into each other, enabling the axial advance and retraction movement to be imparted to the catheter in addition to the steering movement. All the electrical parts that operate in the arm 13 are connected to the rotating element 112 of the collector 12 with electrical cables (see below) which pass through an inclined hole 14 formed in the base 113 of this arm and which pass through the hollow shaft 4, as shown in FIG. 2. FIGS. 5 and 6 show that the body of the arm 13 has a substantially semicircular cross section and carries on its base, along its whole length, a longitudinal channel 15 in which is fixed a C-section guide 16, on the inner sides of which the rollers 17, 17′ of two flat carriages 18, 18′ run and bear alternately, these rollers having different lengths and being positioned one after another. The first of the carriages 18, which is shorter and is close to the base 113 of the arm 13, has a cross-piece 19 which is fixed at its front and supports a nut 20 interacting with a screw 21 which is positioned laterally and parallel to said guide 16 and which has its end facing said base 113 keyed to the slow output shaft of a reversible geared motor unit 22 with an encoder, fixed by flanges to a support 23 fixed inside the arm 13. On the free end of the screw 21 there is keyed an encoder 24 which generates a signal correlated with the rotation of the screw, this signal being processed in combination with that which is produced by the encoder of the motor 22 in order to detect any malfunction of the means for the longitudinal movement of the carriage 18. The longer carriage 18′ is provided, on the end close to the short carriage 18, with an appendage 25 which extends partially in front of the cross-piece 19 and to which a small screw 26 is fixed parallel to the screw 21 with a stud, this small screw passing through a hole in the cross-piece 19 with a degree of clearance and having a cylindrical helical spring 27, loaded by a nut 28, fitted on the part which projects rearwards from the cross-piece. As a result of the compression of said spring 27, the moving element of a force sensor 29 fixed to the front carriage 18′ touches part of the cross-piece 19, is suitably pre-loaded by the calibration of said spring, and is in the optimal condition for generating an electrical signal correlated with the resistance encountered by the catheter in the phase of advance into the patient's cardiovascular system, since the handle of the catheter is associated with the front carriage 18′ as described below. In FIGS. 2 and 3, the number 30 indicates schematically a screw and nut assembly, with the screw fixed to the carriage 18′, which passes with a degree of clearance through a hole formed in the cross-piece 19 and which carries the nut laterally with respect to the latter. This assembly has the function of providing a sufficient travel for bringing the carriages 18, 18′ towards each other, for the operation of the force sensor 29, and of coupling the carriages 18 and 18′ together during the return travel of the two carriages. In the intermediate part of the front carriage 18′ there is fixed in a central position a body 31 on the opposite ends of which the lower ends of H-shaped jaws 33 are pivoted at 32, these jaws having upper limbs which rotatably support rubber-coated rollers 34 which are parallel to each other, the jaws also having intermediate parts of curved shape with anti-friction shoes 35 and being pressed against each other by return springs 36. The handle D of the catheter (FIGS. 2 and 6) can be inserted and fixed between the rollers 34 and said shoes 35 in such a way that it is rapidly removable when necessary, this handle being firmly secured to the carriage 18′ and in axial alignment with the hollow shaft 4, as a result of the appropriate design of the parts which have been described, to ensure that the rotations of this shaft are transmitted to the catheter without undesired translational components.
On the front carriage 18′, upstream of the aforesaid clamp 31-36, there is fixed a support 38 which has a lateral appendage supporting the reversible geared motor unit 39 with an encoder, which drives a screw 40 which is parallel to the carriage 18′ and which interacts with a nut 41 fixed to a sliding block 42 which, by means of its lower longitudinal extension 142, slides in a guided way in a longitudinal median slot 43 of the front carriage 18′. A fork or other suitable gripping device 44, similar to that indicated by N in FIG. 1, is fixed to the sliding block 42 and interacts with the slider or other suitable means F provided on the catheter handle D, to actuate the catheter steering control. A cover 45 with a cross section in the form of an inverted U is fixed to the front carriage 18′ at 46, runs inside the body of the arm 13 of the manipulator (FIGS. 2 and 6) and has a longitudinal slot 47 through which said gripping device 44 passes. During the extension travel of the carriages 18 and 18′ for the longitudinal axial advance movement of the catheter, the upper part of the manipulator arm 13 remains covered by an upper cover 48 fixed to the arm and by lower covers 49 fixed at 50 to a support 51 fixed to the rear carriage 18 (FIGS. 2 and 5). It will be clear that, as shown in FIG. 3 for example, the rotation of the screw 21 results in the longitudinal advance or retraction movement of the catheter and the rotation of the screw 40 results in the steering movement of the catheter. The screw 40 is also connected at its free end to an encoder 52 fixed in the arm 13, the signal from which is processed in combination with that produced by the encoder of the drive unit 39, to detect any malfunctions of this kinematic chain. In FIG. 3, the numbers 53 and 53′ indicate microswitches which interact with opposing appendages 242 of the sliding block 42 to generate end-of-travel signals or commands for this sliding block. Similar microswitches are provided to generate end-of-travel signals or commands for the carriages 18 and 18′, as indicated by the microswitch 54 positioned on board the carriage 18′, which interacts with the end-of-travel switch 55 fixed to the arm 13 and with the microswitch 54′ fixed to an appendage of the support 23, which interacts with a push rod 56 fixed perpendicularly to the cross-piece 19. The electrical commands sent from the various microswitches and encoders and the power supplies to the motors of the units 22 and 39 travel along electrical cables as indicated for example by 57 and 58 in FIG. 2, the latter of which is, for example, in the form of a flexible multi-wire strip partially housed in a recess 59 of an inner side of the arm 13, and is connected to a terminal block 60 fixed laterally to said support 51 (FIGS. 2, 3 and 5). The manipulator which has been described is adapted to be enclosed in a sterilized plastic bag with a length matching the extended dimension of the manipulator, by means of which the manipulator can be fixed for operation in the requisite sterile conditions. Clearly, the manipulator which has been described can be modified in its construction in all of those ways which offer equal utility and which are based on the same inventive concept, without departure from the guiding principle of the present invention as described and illustrated herein and as claimed below.
Patent Application
20100204646
