Patent Publication Number: US-2022233260-A1

Title: Surgical tool

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This Application is a Continuation Application of International Application No. PCT/JP2020/035625 filed on Sep. 18, 2020, which is based on Japanese patent application No. 2019-190340 filed on Oct. 17, 2019 with the Japan Patent Office, the entire contents of each of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     The present disclosure relates to a surgical tool used for medical robots. 
     In recent years, medical treatments using robots have been proposed for the purpose of reducing burdens on operators and reducing manpower at medical facilities. In such cases, a surgical tool is attached to the medical robot and a force is transmitted from the medical robot to the surgical tool to provide the medical treatment. However, when, for example, a size of the surgical tool changes, it becomes difficult to stably and smoothly operate the surgical tool, and difficult to prevent a deterioration in accuracy in estimating the force that will be applied by the surgical tool during treatment. 
     SUMMARY 
     It is an aspect to provide a surgical tool with which it is possible to prevent deterioration in operability and to increase accuracy in estimating a force to be applied by the surgical tool, when a size of the surgical tool is changed. 
     According to an aspect of one or more embodiments, there is provided a surgical tool comprising a driven portion configured to move in a linear motion direction, based on a driving force; a power transmission portion configured to transmit the driving force for moving in the linear motion direction to a treatment portion configured to perform a medical treatment; a conversion portion configured to convert a first amount of movement of the driven portion in the linear motion direction to a second amount of movement different from the first amount of movement and to transmit the second amount of movement to the power transmission portion; and a body that includes the driven portion and the conversion portion, and that supports the treatment portion. 
     According to another aspect of one or more embodiments, there is provided a surgical tool comprising a shaft; a treatment portion provided at a distal end of the shaft; and a body provided at a proximal end of the shaft, wherein the body comprises a driven portion that moves in direction parallel to the shaft, based on a first driving force from a surgical robot; a wire or rod that is connected through the shaft to the treatment portion; a lever that converts the first driving force to a second driving force, the second driving force being different from the first driving force; and a connection portion that is connected to the lever and to the wire or rod, and that transmits the second driving force to the wire or rod. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects will become apparent from the following description of various embodiments and with reference to the following drawings, in which: 
         FIG. 1  is a diagram illustrating an overall configuration of a surgical tool according to various embodiments; 
         FIG. 2  is a diagram illustrating an example configuration of an attachment/detachment surface of a body of the surgical tool in  FIG. 1 , according to various embodiments; 
         FIG. 3  is a diagram illustrating example configurations of a driven portion, a connection portion, a conversion portion, and a power transmission portion of the surgical tool of  FIG. 1 , according to various embodiments; 
         FIG. 4  is a perspective view illustrating example configurations of the driven portion, the connection portion, the conversion portion, and the power transmission portion in  FIG. 3 , according to various embodiments; 
         FIG. 5  is a diagram illustrating an example configuration of the connection portion in  FIGS. 3-4 , according to various embodiments. 
         FIG. 6  is a diagram illustrating transmission of a driving force, according to various embodiments; 
         FIG. 7  is another diagram illustrating transmission of a driving force, according to various embodiments; 
         FIG. 8  is a diagram illustrating configurations of a driven portion, a connection portion, a conversion portion, and a power transmission portion of a surgical tool, according to various embodiments; and 
         FIG. 9  is a diagram illustrating the configuration of the connection portion in  FIG. 8 , according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In recent years, medical treatments using robots have been proposed for the purpose of reducing burdens on operators and reducing manpower at medical facilities. In the field of surgery, medical robots having a remotely operable arm with multi-degrees of freedom have been used to treat patients. 
     Such related art medical robots may have a configuration that allows attachment/detachment to/from the medical robot of a surgical tool that is used for treatment. A driving force in a linear motion direction may be transmitted from the medical robot to the surgical tool through a wire and a rod, arranged within the surgical tool, to allow treatment with a gripper, arranged at an end of the surgical tool. 
     It is advantageous for patients to have treatments with low invasiveness, in which a degree of invasiveness to patients is reduced, to provide an improved cosmetic outcome. Therefore, there is a desire for miniaturization and narrowing in diameter of the surgical tools. 
     At the same time, it is desirable that the medical robots be easy to use such that operators of such medical robots may spend less time to learn how to use the medical robot, to learn how to perform various operation procedures, and to be able to stably and smoothly handle the surgical tool. 
     For example, it has been desired to improve the accuracy in estimating the magnitude, the direction, and so on of an external force acting on the surgical tool based on information, such as the position and the driving force of an actuator that drives the surgical tool, and transmit the estimated external force to an operator remotely handling the surgical tool. The accuracy in estimating an external force depends on the signal to noise (S/N) ratio when the external force is detected and the resolution when an operation amount of the treatment portion (e.g., the gripper, a scissors, monopolar hooks, spatulas, etc.) is measured. 
     When the size of the treatment portion, for example, a gripper, a scissors, monopolar hooks, spatulas, etc., of the surgical tool is changed, the amount of operation of the treatment portion varies even though strokes generated by a driving force transmitted from the medical robot to the surgical tool have the same lengths. In addition, the magnitude of a force generated in the treatment portion also varies even though the magnitude of the driving force is the same. 
     Hence, when the size of the surgical tool attached to the medical robot, that is, for example, the size of the gripper, is changed, the S/N ratio and resolution also vary, affecting the accuracy in estimating the external force. In other words, there is a disadvantage in that it becomes difficult to stably and smoothly operate the surgical tool, and difficult to prevent a deterioration in accuracy in estimating the external force. 
     It is an aspect of one or more embodiments to provide a surgical tool with which it is possible to prevent deterioration in operability and it is possible to improve accuracy in estimating an external force due to a change in size of the surgical tool. 
     The surgical tool according to various embodiments may include a driven portion configured to move upon receipt of an external driving force for moving in a linear motion direction, a power transmission portion configured to transmit the driving force for moving in the linear motion direction to a treatment portion configured to perform a medical treatment, a conversion portion configured to convert an amount of movement of the driven portion in the linear motion direction to transmit the amount of movement converted to the power transmission portion, and a body storing therein the driven portion and the conversion portion and supporting the treatment portion. 
     With this configuration, the provision of the conversion portion enables the amount of movement of the driven portion in the linear motion direction to be converted and transmitted to the power transmission portion. For example, it is possible to set a ratio of conversion by the conversion portion depending on the size of, for example, the treatment portion. Specifically, in the case where the size of the treatment portion is relatively small, a conversion ratio is set to reduce the amount of movement produced by the driving force, and in the case where the size of the treatment portion is relatively large, a conversion ratio is set to increase the amount of movement produced by the driving force. 
     This configuration also makes it easier, even when the size of, for example, the treatment portion is changed, to maintain the relationship between the amount of movement transmitted from outside to the driven portion and the amount of operation of the treatment portion. This configuration also makes it possible to inhibit fluctuations in the S/N ratio and fluctuations in the resolution due to a change in size of, for example, the treatment portion, thus enabling smooth control of operation of the treatment portion and inhibiting deterioration in accuracy in estimating the external force applied to the treatment portion. 
     As a result, it is easier to achieve safety and to inhibit complications in robot surgery with the surgical tool according to various embodiments. In addition, this configuration facilitates improvement in quality of life (QOL) of patients and facilitates reduction of burden on doctors during surgery. Furthermore, this configuration facilitates improvement in the learning curve in robot surgery with the surgical tool. 
     The surgical tool may further comprise a connection portion arranged between the power transmission portion and the conversion portion, and the connection portion may be configured to transmit the driving force transmitted from the conversion portion to the power transmission portion. The provision of the connection portion makes transmission of the driving force from the conversion portion to the power transmission portion easier as compared to a configuration in which the driving force is directly transmitted to the power transmission portion. The provision of the connection portion also makes the setting easier for converting the amount of movement in the linear motion direction into a specified converted amount. 
     The conversion portion may be formed in an elongated shape comprising a first end rotatably supported with respect to the driven portion and a second end rotatably supported with respect to a supporting portion supporting the conversion portion, and the connection portion may be rotatably supported with respect to the conversion portion between the first end and the second end. This shape of the conversion portion makes the setting easier for reducing the amount of movement in the linear motion direction at a specified conversion ratio. In other words, it is possible to change the conversion ratio of the amount of movement in the linear motion direction by changing the ratio between a distance from the position at which the conversion portion is rotatably supported with respect to the driven portion to the position at which the connection portion is rotatably supported, and a distance from the position at which the conversion portion is rotatably supported with respect to the support portion to the position at which the connection portion is rotatably supported. 
     The conversion portion may be formed in an elongated shape comprising a first end rotatably supported with respect to the driven portion and a second end rotatably supported with respect to the connection portion, and a portion of the conversion portion between the first end and the second end may be rotatably supported with respect to a support portion supporting the conversion portion. This shape of the conversion portion makes the setting easier for reducing the amount of movement in the linear motion direction or for increasing the amount of movement at a specified conversion ratio. In other words, it is possible to change the conversion ratio of the amount of movement in the linear motion direction by changing the ratio between a distance from the position at which the conversion portion is rotatably supported with respect to the driven portion to the position at which the conversion portion is rotatably supported with respect to the support portion, and a distance from the position at which the conversion portion is rotatably supported with respect to the connection portion to the position at which the conversion portion is rotatably supported with respect to the support portion. 
     In the conversion portion, a first distance from a position at which the conversion portion is rotatably supported with respect to the driven portion to a position at which the support portion is rotatably supported may be greater than a second distance from a position at which the conversion portion is rotatably supported with respect to the connection portion to the position at which the support portion is rotatably supported. When the first distance is greater than the second distance in the conversion portion, the amount of movement of the driven portion in the linear motion direction may be converted into a smaller amount and transmitted to the power transmission portion. Moreover, the magnitude of the driving force may be converted into a larger magnitude to be transmitted to the power transmission portion. 
     In the conversion portion, a first distance from a position at which the conversion portion is rotatably supported with respect to the driven portion to a position at which the support portion is rotatably supported may be smaller than a second distance from a position at which the conversion portion is rotatably supported with respect to the connection portion to the position at which the support portion is rotatably supported. When the first distance is smaller than the second distance in the conversion portion, the amount of movement of the driven portion in the linear motion direction may be converted into a larger amount and transmitted to the power transmission portion. Moreover, the magnitude of a driving force may be converted into a smaller magnitude to be transmitted to the power transmission portion. 
     According to the surgical tool of various embodiments, the provision of the conversion portion enables the amount of movement of the driven portion in the linear motion direction to be converted and transmitted to the power transmission portion, thus making it possible to inhibit deterioration in operability and possible to increase accuracy in estimating an external force due to a change in size of the surgical tool. 
     Various embodiments of the surgical tool will now be described with reference to the drawings. 
       FIGS. 1-7  illustrate examples of a surgical tool according to various embodiments. A surgical tool  1  may be used for master-slave type surgical robots. 
     As shown in  FIG. 1  and  FIG. 2 , the surgical tool  1  comprises a body  10 , a shaft  60 , a joint portion  61 , and a forceps  70 . The body  10  has a storage space therein. The shaft  60  extends in a rod shape from the body  10 , and the forceps  70  is arranged at an end of the shaft  60  opposite from the body  10 . The forceps  70  corresponds to one example configuration of a treatment portion. In other embodiments, the treatment portion may be any kind of treatment tool, such as, for example, a scissors, monopolar hooks, spatulas, etc. 
     For the purpose of simplifying the description, a direction along an axis line L of the shaft  60  will be described as a Z-axis, and a direction from the body  10  toward the forceps  70  will be described as a positive direction of the Z-axis. A direction orthogonal to the Z-axis and parallel to a paper surface of  FIG. 1  will be described as an X-axis, and a rightward direction with respect to the positive direction of the Z-axis will be described as the positive direction of the X-axis. A direction orthogonal to the X-axis and the Z-axis will be described as a Y-axis, and a direction from a paper surface of  FIG. 1  toward a viewer will be described as a positive direction of the Y-axis. 
     As shown in  FIG. 1 , the shaft  60  may be a cylindrically formed member arranged to extend from the body  10  along the Z-axis direction. The forceps  70  are arranged in the end portion of the shaft  60  in the positive direction of the Z-axis. The shaft  60  comprises the joint portion  61  near the forceps  70 . 
     The joint portion  61  is configured to allow changes in orientation of the forceps  70 , and is rotatable about a rotational axis in the X-axis direction and a rotational axis in the Y-axis direction. The joint portion  61  is configured to be rotated by, for example, a driving force transmitted by a surgical robot. The configuration of the joint portion  61  is not particularly limited. 
     The forceps  70  are arranged in the end portion of the shaft  60  in the positive direction of the Z-axis. The forceps  70  are configured to be opened and closed by a driving force transmitted by the surgical robot. The configuration for the opening/closing action of the forceps  70  is not particularly limited. 
     The body  10  is a portion of the surgical tool  1  that is attached/detached to/from a surgical robot, and is also a portion supporting the shaft  60 . In some embodiments, the surgical robot may be a master-slave type surgical robot. As shown in  FIG. 2 , an attachment/detachment surface  11  of the body  10 , which is attached/detached to/from the surgical robot, comprises driven side slits  12  that are elongated holes extending along a Z-axis direction and are driven by an external force from the surgical robot. In the embodiment illustrated in  FIG. 2 , the surface located on the side in the negative direction of the Y-axis is the attachment/detachment surface  11 . 
     In the driven side slits  12 , a plurality of driven portions  21 , which will be described later, are arranged to be linearly movable with respect to the body  10  along the Z-axis direction. In the embodiment illustrated in  FIG. 2 , three driven side slits  12  are aligned at intervals along an X-axis direction. According to various embodiments, the lengths of the three driven side slits  12  along the Z-axis direction may be the same, or the lengths of two of the driven side slits  12  may be the same and the length of one of the driven side slits  12  may be different, or the lengths of all the driven side slits  12  may be different. In various embodiments, the number of the driven side slits  12  that the body  10  comprises may be more than three, or may be less than three. 
     As shown in  FIGS. 2 to 4 , the body  10  comprises, inside thereof, the driven portions  21 , conversion portions  31 , connection portions  41 , and power transmission portions  51 . It is noted that, for example,  FIG. 4  only illustrates the configuration of one of each of the driven portions  21 , the conversion portions  31 , the connection portions  41 , and the power transmission portions  51  for ease of description, but each of the driven portions  21  is provided with a corresponding conversion portion  31 , a corresponding connection portion  41 , and a corresponding transmission portion  51 . The driven portions  21  are used for transmitting a driving force for moving, for example, the forceps  70 , the conversion portions  31 , the connection portions  41 , and the power transmission portions  51 . 
     The driven portions  21  receive from the surgical robot a driving force for moving the forceps  70  and the like. As shown in  FIG. 2 , the driven portions  21  are arranged to be linearly movable within the driven side slits  12  along the Z-axis direction in accordance with the driving force transmitted from the surgical robot. 
     Each of the driven portions  21  comprises a protrusion  22 , driven side openings  23 , guide portions  25 , through holes  26 , and slide guides  27 . 
     The protrusion  22  is a columnar portion that protrudes from the driven portion  21  in the negative direction of the Y-axis, and, when the driven portion  21  is arranged within the driven side groove  12  (as shown in  FIG. 2 ), the protrusion  22  protrudes in the negative direction of the Y-axis further than the attachment/detachment surface  11 . The protrusion  22  is configured to engage with a recess formed in a component of the surgical robot (not shown) that transmits a driving force. This engagement allows transmission of the driving force for producing linear motion along the Z-axis direction. 
     As shown in  FIG. 3 , the driven side openings  23  are connected to the conversion portion  31  such that the conversion portion  31  is rotatable. Each of the driven side opening  23  is a through-hole which extends along the X-axis direction and accommodates a driven shaft  32  of the conversion portion  31  inserted therein. A cross-section of the driven side opening  23 , that is a cross-section cut along a plane orthogonal to the X-axis, has an elliptical shape with a long axis of the ellipse extending along the Y-axis direction. A cutout portion  24  may be formed around the driven side opening  23  of the driven portion  21  to allow rotational movement of the conversion portion  31  along the cutout portion  24 . 
     As shown in  FIG. 3  and  FIG. 4 , each of the guide portions  25  has the through hole  26  in which the power transmission portion  51  is inserted. A gap is formed between the through hole  26  and the power transmission portion  51 , allowing relative movement between the driven portion  21  and the power transmission portion  51  along the Z-axis direction. In other words, the through holes have a diameter greater than a diameter of the power transmission portion  51 . In the embodiment illustrated in  FIGS. 3-4 , the guide portions  25  are formed at the end of the driven portion  21  in the positive direction of the Z-axis and the end in the negative direction of the Z-axis, protruding in the positive direction of the Y-axis. 
     The slide guides  27  protrude from the driven portion  21  in the positive direction of the X-axis and the negative direction of the X-axis, and each slide guide  27  has a ridge shape extending along the Z-axis direction. The slide guides  27  engage with grooves or step shapes formed inside the driven side slit  12  along the Z-axis direction so as to guide movement of the driven portion  21  along the driven side slit  12 . 
     The conversion portion  31  forms a linkage mechanism or a lever mechanism that transmits a driving force that is transmitted by the surgical robot to the driven portion  21 , to the connection portion  41 . The conversion portion  31  of various embodiments reduces an amount of movement of the driven portion  21  along a linear motion direction, i.e., along the Z-axis direction, and transmits the reduced amount of movement to the connection portion  41 . The conversion portion  31  also increases the magnitude of a driving force in the driven portion  21  and transmits the driving force with the increased magnitude to the connection portion  41 . 
     The conversion portion  31  comprises a lever  35  that is an elongated member extending at least along the Y-axis direction. In one end portion of the conversion portion  31  on a negative direction side of the Y-axis, that is in the end portion of the lever  35  adjacent to the driven portion  21 , a driven shaft hole  32   h  is formed and a driven shaft  32  is arranged in the driven shaft hole  32   h  to extend along the X-axis direction. In the end portion of the conversion portion  31  on a positive direction side of the Y-axis, that is an end portion of the lever  35  opposite to the end portion having the driven shaft hole  32   h  and the driven shaft  32 , a support hole  33   h  is formed and a support shaft  33  supporting the conversion portion  31  is arranged to extend through the support hole  33   h  along the X-axis direction. Between the driven shaft  32  and the support shaft  33  of the conversion portion  31 , a connection shaft hole  34   h  is formed and a connection shaft  34  is arranged to extend through the connection shaft hole  34   h  along the X-axis direction. In some embodiments, the driven shaft  32 , the support shaft  33  and the connection shaft  34  may each be columnar (e.g., a solid shaft) or cylindrical (e.g., a hollow shaft). 
     The end portion of the conversion portion  31  adjacent to the driven portion  21  has a bifurcated shape (most easily seen in  FIG. 4 ) in which the bifurcated ends thereof are spaced apart along the X-axis direction and extend in the negative direction of the Y-axis. Between the bifurcated ends, a portion of the driven portion  21  in which the driven side opening  23  and the cutout portion  24  are formed is inserted. In an area of the conversion portion  31  in which the connection shaft  34  is arranged, a recess that is open in the negative direction of the Z-axis is formed to receive part of the connection portion  41  to be described later. 
     As shown in  FIG. 5 , in the conversion portion  31 , a distance from the center of the support shaft hole  33   h  (and thus the support shaft  33 ) to the center of the connection shaft hole  34   h  (and thus the connection shaft  34 ) may be a first distance D 11 . Moreover, in the conversion portion  31 , a distance from the center of the driven shaft hole  32   h  (and thus the driven shaft  32 ) to the center of the connection shaft hole  34   h  (and thus the connection shaft  34 ) may be a second distance D 12 . 
     As shown in  FIG. 4 , the support shaft  33  is arranged to extend in the positive direction of the X-axis and the negative direction of the X-axis beyond the conversion portion  31 . As shown in  FIG. 3 , the support shaft  33  is arranged in a support groove  16  of a support portion  15  of the body  10 . The support groove  16  is open in the negative direction of the Y-axis and extends along the X-axis direction. 
     As shown in  FIG. 3  and  FIG. 4 , the connection portion  41  comprises a first connection portion  42 , a second connection portion  43 , securing portions  44 , a protruding portion  45  and a connection hole  46 . The connection portion  41  transmits a driving force transmitted from the conversion portion  31  to the power transmission portion  51 . 
     The first connection portion  42  and the second connection portion  43  hold and fasten the power transmission portion  51  therebetween. The securing portions  44  join the first connection portion  42  and the second connection portion  43 . In some embodiments, the securing portions  44  may be screws. However, embodiments are not limited thereto, and in other embodiments, the securing portions  44  may have other structures used for fastening. 
     The first connection portion  42  comprises the protruding portion  45  which is configured to be inserted into the recess described above that is formed around the portion of the conversion portion  31  in which the connection shaft  34  is arranged. The protruding portion  45  comprises the connection hole  46  that is a through hole extending along the X-axis direction. The connection shaft  34  of the conversion portion  31  is rotatably inserted in the connection hole  46  and the connection shaft hole  34   h.    
     The power transmission portion  51  may be a wire or a rod, and transmits a driving force transmitted from the connection portion  41  to the forceps  70 . The power transmission portion  51  is arranged to extend from the inside of the body  10  to the forceps  70  through the shaft  60  along the axis line L. 
     In the embodiment illustrated in  FIGS. 2-4 , the power transmission portion  51  is a wire which is a cord-shaped element. According to various embodiments, the power transmission portion  51  may be entirely formed of a wire, or may be, for example, a rod, or a combination of a rod in one part and a wire in another part. Embodiments are not particularly limited. In some embodiments, the rod may be columnar or cylindrical. 
     The joint portion  61  is configured to be rotated by, for example, a driving force transmitted by the power transmission portion  51 . Moreover, the forceps  70  are configured to be opened and closed by a driving force transmitted by the power transmission portion  51 . 
     Next, a description will be given of an operation of the surgical tool  1  comprising the above-described configuration with reference to  FIG. 6  and  FIG. 7 . First, the operation when the driven portion  21  is moved in the positive direction of the Z-axis will be described with reference to  FIG. 6 , and then the operation when the driven portion  21  is moved in the negative direction of the Z-axis will be described with reference to  FIG. 7 . 
     As shown in  FIG. 6 , when the driven portion  21  is linearly moved in the positive direction of the Z-axis (see bottom larger dashed arrow) by a driving force transmitted from the surgical robot, the motion of the driven portion  21  is transmitted to the conversion portion  31 . Specifically, the conversion portion  31  is rotated about the support shaft  33  such that an end of the lever  35  adjacent to the driven portion  21  moves in the positive direction of the Z-axis. An amount of movement of the driven shaft  32  of the conversion portion  31  to move in the positive direction of the Y-axis caused by the rotation is absorbed by the driven side opening  23  of the driven portion  21 . 
     When the conversion portion  31  is rotated, the motion of the conversion portion  31  (i.e., the lever  35 ) is transmitted to the connection portion  41  and the power transmission portion  51 . Specifically, the rotation of the conversion portion  31  is converted into and transmitted to movement of the connection portion  41  and the power transmission portion  51  in the positive direction of the Z-axis through the connection shaft  34  that extends through the connection shaft hole  34   h  of the conversion portion  31  and the connection hole  46  of the protruding portion  45  of the connection portion  41 . 
     The amount of movement of the connection portion  41  and the power transmission portion  51  in the positive direction of the Z-axis (see top smaller dashed arrow) is reduced as compared to the amount of movement of the driven portion  21 . For example, the amount of movement of the connection portion  41  and the power transmission portion  51  is reduced to a value obtained by multiplying the amount of movement of the driven portion  21  in the positive direction of Z-axis by the first distance D 11  and dividing the resulting value by a combined value of the first distance D 11  and the second distance D 12  (i.e., by D 11 +D 12 ). Moreover, the magnitude of the driving force acting on the connection portion  41  and the power transmission portion  51  in the positive direction of the Z-axis is increased as compared to the magnitude of the driving force acting on the driven portion  21 . For example, the magnitude of the driving force acting on the connection portion  41  and the power transmission portion  51  is increased to a value obtained by multiplying the magnitude of the driving force acting on the driven portion  21  in the positive direction of Z-axis by the combined value of the first distance D 11  and the second distance D 12  (i.e., by D 11 +D 12 ) and dividing the resulting value by the first distance D 11 . 
     As shown in  FIG. 7 , when the driven portion  21  is linearly moved in the negative direction of the Z-axis by a driving force transmitted from the surgical robot, the conversion portion  31  is rotated about the support shaft  33  such that the end of the lever  35  adjacent to the driven portion  21  moves in the negative direction of the Z-axis. The rotation of the conversion portion  31  (i.e., the lever  35 ) is converted into movement of the connection portion  41  and the power transmission portion  51  in the negative direction of the Z-axis through the connection shaft hole  34   h  of the conversion portion  31  and the connection hole  46  of the protruding portion  45  of the connection portion  41 . 
     The amount of movement of the connection portion  41  and the power transmission portion  51  in the negative direction of the Z-axis and the magnitude the driving force acting in the negative direction change in a similar manner as in the case shown in  FIG. 6 ; accordingly the detailed description thereof is omitted for conciseness. 
     According to the surgical tool  1  configured as illustrated in  FIGS. 1-7 , the provision of the conversion portion  31  enables the amount of movement of the driven portion  21  in the linear motion direction to be converted and transmitted to the power transmission portion  51 . For example, it is possible to set the ratio of conversion by the conversion portion  31  depending on the size of, for example, the forceps  70 . Specifically, the conversion ratio is set such that the amount of movement to be transmitted from the driven portion  21  to the power transmission portion  51  is reduced based on the extent of a decrease in size of the forceps  70 . 
     This configuration makes it easier, even when the size of, for example, the forceps  70  is changed, to maintain the relationship between the amount of movement transmitted from the surgical robot to the driven portion  21  and the amount of operation of the forceps  70 . In the case where the surgical robot comprises a sensor to detect an external force applied to the forceps  70  and/or a sensor, such as an encoder, to detect a driven amount of the forceps  70 , it is possible to inhibit fluctuations in the S/N ratio and fluctuations in the resolution due to a change in size of, for example, the forceps  70 . This configuration thus enables smooth control of the operation of the forceps  70  and inhibits deterioration in accuracy in estimating an external force applied to the forceps  70 . 
     As a result, it is easier to achieve safety and to inhibit complications in robot surgery with the surgical tool  1  according to various embodiments. In addition, this configuration facilitates improvement in Quality of Life (QOL) of patients and facilitates a reduction of burden on doctors during surgery. Furthermore, this configuration facilitates improvement in the learning curve in robot surgery with the surgical tool  1 . 
     The provision of the connection portion  41  makes transmission of a driving force to the power transmission portion  51  easier as compared to a configuration in which a driving force is directly transmitted from the conversion portion  31  to the power transmission portion  51 . This configuration also makes the setting easier for converting the amount of movement in the linear motion direction into a specified converted amount. 
     The shape of the conversion portion  31  in the embodiment illustrated in  FIGS. 1-7  makes the setting easier for reducing the amount of movement in the linear motion direction at a specified conversion ratio. In other words, it is possible to change the conversion ratio of the amount of movement in the linear motion direction by changing the ratio between the first distance D 11 , which is from the position at which the conversion portion  31  is rotatably supported with respect to the support portion  15  to the position at which the connection portion  41  is rotatably supported, and the second distance D 12 , which is from the position at which the conversion portion  31  is rotatably supported with respect to the driven portion  21  to the position at which the connection portion  41  is rotatably supported. 
       FIGS. 8-9  illustrate a surgical tool according to various embodiments. In the description of  FIGS. 8-9 , like reference numbers refer to like elements/components and a repeated description thereof is omitted for conciseness. The description will be given with regard to the configuration of the conversion portion and the surrounding components thereof with reference to  FIG. 8  and  FIG. 9 , and the description of other components will not be repeated for conciseness. 
     As shown in  FIG. 8 , the body  10  of a surgical tool  101  comprises a driven portion  121 , a conversion portion  131 , a connection portion  141 , and the power transmission portion  51 . The connection portion  141  is arranged at the end of the conversion portion  131  in the positive direction of Y-axis, rather than being arranged between the support shaft and the driven shaft. 
     The driven portion  121  comprises the protrusion  22 , the driven side openings  23 , and the slide guides  27 . The driven portion  121  also comprises the cutout portions  24 . In the embodiment illustrated in  FIGS. 8-9 , the driven portion  121  omits the guide portions  25  and the through holes  26 . However, embodiments are not limited to this configuration and, in some embodiments, the driven portion  121  may comprise the guide portions  25  and the through holes  26 . 
     The conversion portion  131  forms a linkage mechanism or a lever mechanism that transmits a driving force that is transmitted by the surgical robot to the driven portion  121 , to the connection portion  141 . The conversion portion  131  according to various embodiments reduces or increases the amount of movement of the driven portion  121  along the linear motion direction, i.e., along the Z-axis direction, and transmits the reduced or increased amount of movement to the connection portion  141 . The conversion portion  131  also increases or reduces the magnitude of a driving force in the driven portion  121  and transmits the driving force with the increased or reduced magnitude to the connection portion  141 . 
     The conversion portion  131  comprises a lever  135  that is an elongated member extending at least along the Y-axis direction. In the end portion of the conversion portion  131  on the negative direction side of the Y-axis, that is in the end portion of the lever  135  adjacent to the driven portion  121 , the driven shaft hole  32   h  is formed and the driven shaft  32  is arranged in the driven shaft hole  32   h  to extend along the X-axis direction. In the end portion of the conversion portion  131  on the positive direction side of the Y-axis, that is, an end portion of the lever  35  opposite to the end portion having the driven shaft hole  32   h  and the driven shaft  32 , a connection shaft hole  134   h  is formed and a connection shaft  134  is arranged in the connection shaft hole  134   h  to extend along the X-axis direction. 
     Between the driven shaft  32  and the connection shaft  134  of the conversion portion  131 , a support shaft hole  133   h  is formed and a support shaft  133  supporting the conversion portion  131  is arranged in the support shaft hole  133   h  to extend along the X-axis direction. The support shaft  133  is rotatably held with respect to the support portion  15  of the body  10 . In some embodiments, the driven shaft  32 , the support shaft  133  and the connection shaft  134  may each be columnar (e.g., a solid shaft) or cylindrical (e.g., a hollow shaft). 
     As shown in  FIG. 9 , in the conversion portion  131 , a distance from the center of the driven shaft hole  32   h  (and thus the driven shaft  32 ) to the center of the support shaft hole  133   h  (and thus the support shaft  133 ) is a first distance D 21 . Moreover, in the conversion portion  131 , a distance from the center of the support shaft hole  133   h  (and thus the support shaft  133 ) to the center of the connection shaft hole  134   h  (and thus the connection shaft  134 ) is a second distance D 22 . 
     As shown in  FIG. 8 , the connection portion  141  transmits a driving force transmitted from the conversion portion  131  to the power transmission portion  51 . In comparison with the connection portion  41  in the embodiment illustrated in  FIGS. 1-7 , the connection portion  141  is connected to the connection shaft  134  of the conversion portion  131  such that the connection shaft  134  is rotatable. That is, the protruding portion  45  and the connection hole  46  and positioned such that an axis of the connection hole  46  aligns with the connection shaft hole  134   h  and the connection shaft  134  extends through the connection hole  46  and the connection shaft hole  134   h.    
     Next, a description will be given of an operation of the surgical tool  101  comprising the configuration illustrated in  FIG. 8 , with reference to  FIG. 8 . 
     When the driven portion  121  is linearly moved in the positive direction of the Z-axis by a driving force transmitted from the surgical robot, the motion of the driven portion  121  is transmitted to the conversion portion  131 . Specifically, the conversion portion  131  is rotated about the support shaft  133  such that the end portion of the lever  135  adjacent to the driven portion  121  moves in the positive direction of the Z-axis. 
     When the conversion portion  131  is rotated, the motion of the conversion portion  131  is transmitted to the connection portion  141  and the power transmission portion  51 . Specifically, the rotation of the conversion portion  131  is converted into movement of the connection portion  141  and the power transmission portion  51  in the negative direction of the Z-axis. 
     An absolute value of an amount of movement of the connection portion  141  and the power transmission portion  51  in the negative direction of the Z-axis is a value obtained by multiplying an absolute value of an amount of movement of the driven portion  121  in the positive direction of the Z-axis by the second distance D 22  illustrated in  FIG. 9  and dividing the resulting value by the first distance D 21  illustrated in  FIG. 9 . Moreover, a magnitude of the driving force acting on the connection portion  41  and the power transmission portion  51  in the positive direction of the Z-axis is a value obtained by multiplying the magnitude of the driving force acting on the driven portion  21  in the positive direction of the Z-axis by the first distance D 21  and dividing the resulting value by the second distance D 22 . 
     When the first distance D 21  is greater than the second distance D 22 , the absolute value of the amount of movement of the connection portion  141  and the power transmission portion  51  in the negative direction of the Z-axis becomes smaller than the absolute value of the amount of movement of the driven portion  121  in the positive direction of the Z-axis. The magnitude of the driving force acting on the connection portion  41  and the power transmission portion  51  in the positive direction of the Z-axis becomes larger than the magnitude of the driving force acting on the driven portion  21  in the positive direction of the Z-axis. 
     When the first distance D 21  is smaller than the second distance D 22 , the absolute value of the amount of movement of the connection portion  141  and the power transmission portion  51  in the negative direction of the Z-axis becomes larger than the absolute value of the amount of movement of the driven portion  121  in the positive direction of the Z-axis. The magnitude of the driving force acting on the connection portion  41  and the power transmission portion  51  in the positive direction of the Z-axis becomes smaller than the magnitude of the driving force acting on the driven portion  21  in the positive direction of the Z-axis. When the first distance D 21  is equal to the second distance D 22 , the absolute value of the amount of movement of the connection portion  141  and the power transmission portion  51  in the negative direction of the Z-axis is the same as the absolute value of the amount of movement of the driven portion  121  in the positive direction of the Z-axis. The magnitude of the driving force acting on the connection portion  141  and the power transmission portion  51  in the positive direction of the Z-axis is the same as the magnitude of the driving force acting on the driven portion  121  in the positive direction of the Z-axis. 
     In the configuration illustrated in  FIGS. 8-9 , the movement of the conversion portion  131 , the connection portion  141 , and the power transmission portion  51  when the driven portion  121  is linearly moved in the negative direction of the Z-axis by a driving force transmitted from the surgical robot is in a direction opposite to the direction of the movement described above (i.e., is in the positive direction of the Z-axis). Accordingly, a detailed description thereof is omitted for conciseness. Moreover, the amount of movement of the connection portion  141  and the power transmission portion  51  along the Z-axis direction and the magnitude the driving force change in a similar manner, and therefore a detailed description thereof is also omitted for conciseness. 
     According to the configuration illustrated in  FIGS. 8-9 , the configuration of conversion portion  131  makes the setting easier for reducing the amount of movement in the linear motion direction or for increasing the amount of movement at a specified conversion ratio. In other words, it is possible to change the conversion ratio of the amount of movement in the linear motion direction by changing the ratio between the first distance D 21 , which is from the position at which the conversion portion  131  is rotatably supported with respect to the driven portion  121  to the position at which the conversion portion  131  is rotatably supported with respect to the support portion  15 , and the second distance D 22 , which is from the position at which the conversion portion  131  is rotatably supported with respect to the connection portion  141  to the position at which the conversion portion  131  is rotatably supported with respect to the support portion  15 . 
     Setting the first distance D 21  greater than the second distance D 22  in the conversion portion  131  enables the amount of movement of the driven portion  121  in the linear motion direction to be converted into a smaller amount and transmitted to the power transmission portion  51 . Moreover, the magnitude of a driving force is converted into a larger magnitude to be transmitted to the power transmission portion  51 . 
     Setting the first distance D 21  smaller than the second distance D 22  in the conversion portion  131  enables the amount of movement of the driven portion  121  in the linear motion direction to be converted into a larger amount and transmitted to the power transmission portion  51 . Moreover, the magnitude of a driving force is converted into a smaller magnitude to be transmitted to the power transmission portion  51 . 
     It is to be noted that the technical scope of the present disclosure should not be limited to the above-described embodiments, and various modifications thereto may be made without departing from the intent of the present disclosure. For example, in the embodiments described above, the treatment portion arranged at the distal end of the shaft  60  is the forceps  70 . The treatment portion, however, is not limited to the forceps  70  and may be other instruments used for, for example, endoscope surgery. For example, the treatment portion may be a scissors, monopolar hooks, spatulas, etc. 
     In addition, the specific shapes of the conversion portions  31  and  131  are not limited to those described in the above-described embodiments. Any shapes that would achieve the same effect may be used, and thus the shapes are not limited to particular shapes. 
     It should be understood that the present disclosure is not limited to the above embodiments, but various other changes and modifications may be made therein without departing from the spirit and scope as set forth in appended claims.