Abstract:
A tool identification system, comprising: a tool holder allowing removable attachment thereto of any one of a plurality of tools; a sensor arrangement operable to sense features present on a tool attached to the tool holder; a processor operable to identify uniquely, from the sensed features, the type of the tool attached to the tool holder; and an insulation arrangement provided between the tool holder and the sensor arrangement, thereby electrically insulating the tool holder from the sensor arrangement.

Description:
RELATED U.S. APPLICATIONS  
         [0001]    Not applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         REFERENCE TO MICROFICHE APPENDIX  
         [0003]    Not applicable.  
         FIELD OF THE INVENTION  
         [0004]    This invention relates to a tool holder arrangement, and in particular concerns a tool holder arrangement incorporating a system for uniquely identifying a surgical tool attached to a tool holder.  
         BACKGROUND OF THE INVENTION  
         [0005]    The use of medical robots has become widespread in recent years, in particular for surgical procedures requiring a high degree of precision, for instance minimal access or “keyhole” surgery.  
           [0006]    Typically, a medical robot comprises an arm which is movable under computer control, and to which any one of several different tools may be attached. During the course of a surgical procedure, several different tools may be required, and each will be attached in turn to the arm of the medical robot.  
           [0007]    Because the tools must be sterile to qualify for use in surgical procedures, conventional identification means such as labeling or marking may not be available for the purpose of distinguishing between tools. In addition, electrical safety and clinical practice requires that the patient is electrically “floating”, that is, isolated from any power sources and not earthed. Hence, when the tool contacts the patient during a surgical procedure, this contact must not provide a ground path through which current could flow between the patient and ground.  
           [0008]    Because a medical robot is a safety-critical device, it is a requirement in most jurisdictions for medical robots to be immune from single-point failures. In other words, it is preferable for there to be two independent means for verifying which tool is attached to the arm of the robot.  
           [0009]    Object of the Invention  
           [0010]    The present invention seeks to alleviate some or all of the difficulties.  
         BRIEF SUMMARY OF THE INVENTION  
         [0011]    According to this invention there is provided a tool holder arrangement including: a tool holder to be mounted on a support and allowing removable attachment thereto of any one of a plurality of tools; a sensor arrangement operable to sense at least one feature present on a tool when attached to the tool holder, being a feature or features unique to the specific tool; and a processor operable to identify uniquely, from the sensed feature or features, the type of the tool attached to the tool holder, the tool holder and the sensor arrangement being such that a tool is electrically isolated from the support when the tool is attached to the tool holder.  
           [0012]    Preferably the sensor arrangement is operable to sense at least one feature present on a tool in the form of a projection on the tool.  
           [0013]    Alternatively the sensor arrangement is operable to sense at least feature present on a tool in the form of a recess on the tool.  
           [0014]    Conveniently the sensor arrangement includes a plurality of axially movable rods extending to a face of the tool holder which is adjacent the tool when the tool is attached to the tool holder, there being a respective switch element actuable in response to movement of each of the rods.  
           [0015]    Preferably each rod is resiliently biased to an initial position by me a spring.  
           [0016]    Advantageously the rods are evenly angularly spaced about the circumference of a notional circle.  
           [0017]    Alternatively the rods are arranged in linear co-alignment.  
           [0018]    In a further modified embodiment of the invention the sensor arrangement is operable to sense at least one feature present on the tool in the form of a magnetic element.  
           [0019]    Preferably the sensor arrangement includes a plurality of detectors responsive to a magnetic field.  
           [0020]    Advantageously the tool holder incorporates a connector element to which the tool may be mounted, the connector element being formed of or mounted on an element of insulating material.  
           [0021]    Preferably the processor is adapted to generate an alarm signal if only one said feature on a tool is detected.  
           [0022]    The tool holder may be provided in combination with at least one tool.  
           [0023]    Conveniently the tool is provided with two projecting elements positioned to be co-aligned with two said rods.  
           [0024]    In an alternative embodiment the tool is provided with two recesses positioned to be co-aligned with two said rods.  
           [0025]    In a further alternative embodiment the tool is provided with two magnetic elements positioned to be co-aligned with two said detectors.  
           [0026]    The tool holder arrangement may be incorporated into a robot. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0027]    In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0028]    [0028]FIG. 1 is a schematic cut-away view of part of an arm provided a tool holder arrangement in accordance with the invention, and a tool; and  
         [0029]    [0029]FIG. 2 is a schematic elevational view of a printed circuit suitable for use with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    Referring to FIG. 1, a tool-receiving end  1  of the arm of a medical robot is shown. The tool-receiving end comprises a housing  2 , which is substantially circular in cross section. A substantially circular printed circuit board (PCB)  3  is provided within the housing, the PCB  3  being of slightly smaller radius than the housing  2 , and being arranged to be coaxial therewith. The PCB  3  is held in place by suitable mounts  4 , which are each attached to an interior surface  5  of the housing  2 .  
         [0031]    Supported on a front surface  6  of the housing  2  is a substantially cylindrical insulating block  7 , which is formed from a substantially electrically non-conducting material. The insulating block  7  is also arranged to be substantially coaxial with the tool-receiving end  1 . Mounted on the insulating block  7 , on the opposite side thereof from the tool-receiving end  1 , is a connector  8 , which is substantially cylindrical (and again coaxial with the tool-receiving end  1 ), but which has a groove  9  running around the outer circumferential surface  10  thereof. The groove  9  has a flat bottom and the side walls thereof are inclined to the bottom. In an alternative arrangement the connector  8  is of insulating material.  
         [0032]    Eight rods  11  are provided, which pass through bores which extend through the connector  8 , the insulating block  7  and into the interior of the housing  2 . The rods  11  are mounted within respective bores in the connector  8 , the insulating block  7  and the housing  2 . The bores are parallel and evenly angularly spaced about the circumference of a notional circle. The rods  11  are formed from electrically non-conducting material.  
         [0033]    Helical springs  12  are provided around portions of each of the rods  11 , in enlarged chambers formed at the end of each bore. One end of each spring  12  engages the outer surface  6  of the housing  2 , and the other end of each spring  12  engages a flange on the respective rod  11  so that, in a resting position of the spring  12 , the rod  11  is held so that a proximal end  13  thereof rests close to the PCB  3 . It will be understood that, if any of the rods  11  are pushed inwardly towards the PCB  3 , the respective spring  12  will act to oppose this motion, and once the pushing force is removed the spring  12  will return the rod  11  to its resting position.  
         [0034]    Indentations  14  are provided in the end of the connector  8 , the indentations being substantially cylindrical and each being centered around a respective one of the rods  11 . The connector  8  is configured so that each rod  11  protrudes into the space formed by an indentation  14  when in the resting position but does not protrude past a front surface  15  of the connector  8 .  
         [0035]    The PCB  3  is provided with eight micro-switches  16  (as can be seen from FIG. 2), which are equi-angularly spaced about the circumference of a notional circle. The arrangement of these micro-switches  16  is such that a respective micro-switch  16  lies opposite the proximal end  13  of each rod  11  when the rods  11  are in their resting positions. A processor  17  is mounted on the PCB  3 , the processor being connected to the micro-switches  16 .  
         [0036]    A connecting portion  18  of a surgical tool is also shown in FIG. 1. The connecting portion  18  is formed at the end of a shank of the tool. The connecting portion  18  comprises a collar  19  which surrounds a circular recess  20 . The recess  20  has a base  21 . Provided on the base  21  are two spaced-apart protrusions in the form of axially extending pins  22 .  
         [0037]    The collar  19  is provided, at diametrically opposed positions, with two radially inwardly directed cylindrical recesses  23 ,  24 . Each recess  23 , 24  contains a sliding detent element  25 ,  26 , there being a respective spring  27 ,  28  between the base of each detent  25 ,  26  and the base of the respective recess  23 ,  24 . The springs  27 ,  28  serve to bias the detents  25 ,  26  radially inwardly. The inwardly protruding end of each detent  25 ,  26  which extends into the recess  20  has a configuration corresponding to that of the groove  9 . The detents  25 ,  26  may thus form a “snap” coupling with the recess  9 , securing the tool which is provided with the connecting portion  18  to the connector  8 . A projection (not shown) provided on the connecting portion  18  may engage a key-way (not shown) provided on the connector  8  so that the tool may only be mounted on the connector in a specific predetermined orientation.  
         [0038]    Upon releasing the tool from the arm of the medical robot, the spring will remove the rods  11  from engagement with the micro-switches  16 .  
         [0039]    It will be appreciated that, with the above-described system, four different tools can be provided, each with a connecting portion  18  as described, but with the two pins  22  on each of the connecting portions  18  being provided in different locations so as to correspond to a different pair of micro-switches  16 . Ideally, each tool will have pins  21  at locations to correspond to two micro-switches  16 , neither of which is also associated with any other tool. Hence, either of the two micro-switches  16  that are activated when a particular tool is attached to the arm of the medical robot can be used by the processor  17  to identify uniquely the type of the tool. However, if both switches are closed, effectively there is a double confirmation of the identity of the tool.  
         [0040]    Of course, a greater number of micro-switches  16  may be provided PCB  3 , to accommodate a greater variety of possible tool types.  
         [0041]    In preferred embodiments of the prevent invention, an alarm is raised if only one micro-switch  16  is activated, or if a combination of two or more micro-switches  16  that do not correspond to an individual tool are activated.  
         [0042]    In the above-described example, the circular arrangement of the micro-switches  16  means that the tool must be attached to the arm of the medical robot in a certain predetermined orientation. However, in alternative embodiments, the micro-switches  16  are arranged so that, irrespective of the orientation with which the tool is attached to the arm of the medical robot, the tool can be correctly identified. For instance, the micro-switches  16  may be arranged in a substantially straight line extending from the center of the PCB  3  to an edge thereof, with each tool being provided with two concentric rings of pins, similar to the pins  22 , on the base  21  of the recess  20 . The distance of each of the rings or pins from the center of the base  21  indicates which type of tool it is, and clearly micro-switches  16  at certain distances from the center of the PCB  3  will be activated when this system is employed, irrespective of the relative orientations of the tool and arm.  
         [0043]    In an alternative embodiment of the present invention, each tool may be provided with indentations, rather than pins  22 , in the base  21  of the recess  20  thereof. In this embodiment, the ends of the rods  11  may protrude past the forward-facing surface  15  of the connector  8 , and it will be understood that the tool can then be identified from a combination of two micro-switches  16  that are not activated when the tool is connected to the arm of the medical robot.  
         [0044]    It is also envisaged that the present invention may operate by the presence of one or more magnets on the tool, with the connecting portion  18  of the arm of the medical robot being provided with a number of magnetic detectors. When the tool and the arm are connected to one another the magnetic detectors such as Hall effect switches or magnetic reed switches will lie directly opposite the magnets and will be able to detect the presence thereof.  
         [0045]    It will be understood that a preferred embodiment of the present invention provides a reliable system of uniquely identifying tools attached to the arm of a medical robot, while maintaining electrical insulation between the tool and the arm, and which alleviates many difficulties associated with the prior art.  
         [0046]    In the present Specification “comprises” means “includes or consists of” and “comprising” means “including or consisting of”.  
         [0047]    The features disclosed in the foregoing description, or the following Claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof.