Patent ID: 12220196

MODE FOR CARRYING OUT THE INVENTION

In the description below, the technology according to the present disclosure will be explained in the following order, with reference to the drawings.

A. Problems with a Surgical Tool Unit

B. Example Configuration (1) of a Surgical Tool Unit (with reference toFIGS.1to22)

C. Example Configuration (2) of a Surgical Tool Unit (with reference toFIGS.23to30)

D. Example Configuration (3) of a Surgical Tool Unit (with reference toFIGS.31to40)

E. Modifications of the Surgical Tool Unit

F. Example Applications of the Surgical Tool Unit (with reference toFIGS.41and42)

G. Effects

A. Problems with a Surgical Tool Unit

A surgical tool to be used in a surgical robot preferably has a total of three degrees of freedom, which are two degrees of freedom of rotation and a degree of freedom of opening and closing at the end. Specifically, such a surgical tool includes an open-close end effector formed with a pair of opposing jaw members, a wrist supporting the end effector, and a shaft that has a longitudinal axis and connects the wrist to its end, for example. This kind of surgical tool has a degree-of-freedom configuration including: a first axis for turning the wrist about the yaw axis, for example, with respect to the end of the shaft; a second axis for turning the orientation of the end effector about the pitch axis, for example, with respect to the wrist; and a third axis (an open-close shaft) for opening and closing the jaw members. In the description below, an embodiment in which the second axis and the open-close shaft are coaxial will be described.

In laparoscopic surgery, for example, the end (distal end) side of the shaft is normally used while inserted in a body cavity via a trocar, and therefore, needs to have a small diameter. Further, in brain surgery, treatment needs to be performed on a narrow operative field, and therefore, it is necessary to minimize hindering of the field of view of the operator, depending on the surgical tool. In view of this, the driving forces generated by actuators (electromagnetic rotary motors, for example) disposed on the root side (the proximal end) of the shaft are basically transmitted via cables, so as to operate the surgical tool. Specifically, three systems of cables for transmitting the power for turning the wrist about the first axis with respect to the shaft end, the power for turning the monitoring orientation about the second axis with respect to the wrist, and the power for opening and closing the open-close end effector are required, and these cables are inserted through the shaft. Further, in a power transmission mechanism using cables, a plurality of pulleys is used, such as capstans for applying power to the cables or converting the forces from the cables into axial forces, and idler pulleys to be used for adjusting the layout of the cables in the shaft and applying constant tension to the cables.

Here, according to a method by which the layout of cables is adjusted with idler pulleys, high slidability is achieved. Thus, excellent durability and reliability are also achieved, and torque control on the end effector can be performed with high precision. On the other hand, the number of components increases by the number of idler pulleys. Therefore, the surgical tool (or the outer diameter of the shaft, for example) becomes larger in size, and the costs become higher. According to a method by which the cables are made to slide on an R surface formed on a peripheral component without the use of any idler pulley, it is possible to reduce the number of components and achieve a smaller size by eliminating the idler pulleys. However, the cables easily deteriorate due to abrasion, and the reliability becomes poorer. Furthermore, the friction coefficient on the sliding surface is high, which leads to disturbance. As a result, torque control becomes difficult. It is also possible to adopt a method by which cables are inserted through a round hole formed along a desired layout. However, backlash occurs when the cables inserted through the round hole are handled.

Also, a cable loop type or an individual cable traction type can be normally adopted as a method for driving a capstan on the output side with a cable tractive force generated by an actuator.

In the former cable loop type, the cables are laid out by looping the output-side capstan and the drive-side capstan that is rotated by drive of an actuator. With the cable loop type, the forward and backward cables can be controlled in an antagonistic manner by a single actuator, it is easy to make the drive unit smaller in size and lighter in weight. Furthermore, there is no need to compensate the pre-tension of the cables with an output of the actuator, and thus, the actuator can be easily made smaller in size. However, in the case of a device configuration in which the entire length of the looped cables fluctuates due to the influence of the axis angle of the control target and other axes, the pre-tension to be applied to the cables fluctuates, and therefore, it is difficult to adopt the cable loop type. For example, when the wrist is driven to rotate about the first axis, the lengths of the respective cable for driving the respective jaw members change.

On the other hand, the latter individual cable traction type has a configuration in which the forward and backward cables attached to the capstans on the output side are pulled by individual actuators, and the forward and backward cables can be controlled independently of each other. Thus, the degree of freedom in designing the configuration of a surgical tool becomes higher. However, the pre-tension of the cables needs to be compensated with outputs of the actuators. Although it is also possible to compensate the pre-tension using a coil spring, a weight, or the like, control becomes difficult because the corresponding spring force or inertial force is applied when driving is performed with the actuators.

In both the cable loop type and the individual cable traction type, one traction motor is required for each one cable. If heavy and large motors for compensating the pre-tension of the cables are installed as many as the number of cables, the housing space and the device weight increase. Also, in both the cable loop type and the individual cable traction type, a total of two cables that are forward and backward cables are used for bidirectionally rotating one output-side capstan. Therefore, two idler pulleys for adjusting the layout of the cables are also required, and the number of components increases.

Furthermore, a yaw operation, a pitch operation, and an opening and closing operation of the end effector at the end of a surgical tool need to be performed with a structure that does not cause cross-axis interference. Cross-axis interference will lead to the following events, for example.

(1) When the yaw axis angle is changed, the pitch axis passively rotates.

(2) When the yaw axis angle is changed, the pre-tension of the cables fluctuates.

In view of the above, this specification discloses below a surgical tool that achieves size and weight reduction by adjusting the layout of cables with a smaller number of idler pulleys, and pulling the cables by a method that facilitates application of desired pre-tension. This specification also discloses below a computer-aided surgery system and a surgical operating unit.

B. Example Configuration (1) of a Surgical Tool Unit

FIG.1shows an example configuration of a surgical tool unit to which the technology according to the present disclosure is applied. A surgical tool unit100shown in the drawing includes a hollow shaft102having a longitudinal axis, a surgical tool unit end portion101at one end of the shaft102, and a surgical tool unit drive unit103at the other end of the shaft102. The surgical tool unit end portion101includes a wrist element capable of turning about a first axis parallel to the yaw axis with respect to the shaft102, and an end effector at the end of the wrist element. The end effector performs an opening and closing operation with a second axis functioning as the open-close shaft, the second axis being parallel to the pitch axis. The end effector is formed with a pair of opposing jaw members that turn about the second axis and perform an opening and closing operation. However, the second axis is located at a position offset from the first axis. Meanwhile, the surgical tool unit drive unit103includes two actuators that drive the respective jaw members in the surgical tool unit end portion101, and one actuator that drives the wrist.

FIGS.2and3show the surgical tool unit end portion101in an enlarged manner (however, the viewing direction is different betweenFIGS.2and3). Also,FIGS.4and5show the surgical tool unit drive unit103in an enlarged manner (however, the viewing direction is different betweenFIGS.4and5). Further,FIG.6shows an example degree-of-freedom configuration of the surgical tool unit100. Furthermore,FIG.7shows a six-sided view of the surgical tool unit100. Further,FIGS.8and9show a simplified configuration relating to the degree of freedom of the surgical tool unit100.

The surgical tool unit end portion101includes a wrist element WE and an open-close end effector. The end effector includes a pair of opposing jaw members: a first jaw member J1and a second jaw member J2(seeFIGS.2and3, for example). The wrist element WE is supported at a portion near the root so as to be able to turn about the first axis parallel to the yaw axis at the end (distal end) of the shaft102. Further, the first jaw member J1and the second jaw member J2that constitute the end effector are supported so as to be able to turn about the second axis parallel to the pitch axis at the end of the wrist element WE. The first jaw member J1and the second jaw member J2open and close when the open angle with the second axis serving as the open-close shaft changes.

Meanwhile, the surgical tool unit drive unit103includes a first motor M1to be used for driving the first jaw member J1, a second motor M2to be used for driving the second jaw member J2, and a third motor M3to be used for driving the wrist element WE (seeFIGS.4,5, and6, for example). Further, first to third motor capstans MC1, MC2, and MC3as drive capstans are attached to the output shafts of the first to third motors M1to M3, respectively (seeFIG.6, for example). Although a rotary motor is assumed to be used for each of the first to third motors M1to M3, a motor with a speed reducer may also be used.

A set of first forward and backward cables C1aand C1bis wound around the first motor capstan MC1, and the first motor capstan MC1is rotated by the first motor M1, so that the first jaw member J1is driven by a cable loop method. Also, a set of second forward and backward cables C2aand C2bis wound around the second motor capstan MC2, and the second motor capstan MC2is rotated by the second motor M2, so that the second jaw member J2is driven by the cable loop method.

Referring toFIGS.4and5, the first motor M1is supported on a first slide base SB1that slides in the longitudinal axis direction of the shaft102, and the second motor M2is supported on a second slide base SB2that slides in the longitudinal axis direction of the shaft102. Further, a set of third forward and backward cables C3aand C3bis wound around the third motor capstan MC3via third idler pulleys P3aand P3b. The other end of the third forward cable C3ais secured to the first slide base SB1, and the other end of the third backward cable C3bis secured to the second slide base SB2. The third motor M3then pulls the set of third forward and backward cables C3aand C3bby the cable loop method, so that the first slide base SB1and the second slide base SB2can be moved forward and backward in opposite directions in the longitudinal axis direction of the shaft102(seeFIG.6, for example).

Referring toFIGS.2and3, the first jaw member J1is supported by the wrist element WE at a portion near the base, so as to be able to turn about the second axis. Likewise, the second jaw member J2is supported by the wrist element WE at a portion near the base, so as to be able to turn about the second axis. Accordingly, each of the first jaw member J1and the second jaw member J2is turned about the second axis, so that the open angle of the first jaw member J1and the second jaw member J2become larger or smaller (in other words, so that a change is caused in the difference between the angles of the first jaw member J1and the second jaw member J2about the second axis). Thus, an opening and closing operation of the end effector is performed. Further, the first jaw member J1and the second jaw member J2are simultaneously turned about the second axis, while the open angle of the first jaw member J1and the second jaw member J2are maintained at constant angles (in other words, to cause a change in the sum of the angles of the first jaw member J1and the second jaw member J2about the second axis). Thus, a turning operation of the end effector formed with the first jaw member J1and the second jaw member J2about the second axis is performed.

Referring toFIGS.2,3, and6, a first jaw capstan JC1having the above-mentioned second axis as its rotation axis is provided near the root of the first jaw member J1. The set of first forward and backward cables C1aand C1bis wound around the first jaw capstan JC1. As shown inFIGS.4to6, the set of first forward and backward cables C1aand C1bis wound around the first motor capstan MC1on the side of the surgical tool unit drive unit103. Accordingly, a tractive force acts on one of the cables C1aand C1bdepending on the rotation direction of the first motor M1, and a turning operation of the first jaw member J1about the second axis is performed. As the first jaw member J1is driven by the cable loop method using the set of first forward and backward cables C1aand C1b, it is possible to make the range of movement of the first jaw member J1wider.

Also, referring toFIGS.2,3, and6, a second jaw capstan JC2having the above-mentioned second axis as its rotation axis is provided near the root of the second jaw member J2. The set of second forward and backward cables C2aand C2bis wound around the second jaw capstan JC2. As shown inFIGS.4to6, the set of second forward and backward cables C2aand C2bis wound around the second motor capstan MC2on the side of the surgical tool unit drive unit103. Accordingly, a tractive force acts on one of the cables C2aand C2bdepending on the rotation direction of the second motor M2, and a turning operation of the second jaw member J2about the second axis is performed. As the second jaw member J2is driven by the cable loop method using the set of second forward and backward cables C2aand C2b, it is possible to make the range of movement of the second jaw member J2wider.

Next, the layout of the respective cables in the surgical tool unit100, and a specific method for operating the surgical tool unit end portion101are described.

Idler pulleys are used to redirect each cable of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bat a portion near the first axis so that each of the cables is inserted through the shaft102, and to adjust the layout of the respective cables in the shaft102.

As shown inFIGS.2,3, and6, the first forward cable C1ais pulled in a direction orthogonal to the second axis. However, the direction of the cable C1ais switched to a direction orthogonal to the first axis by a first idler pulley P11athat uses the first axis as its rotation axis, and further, the layout is adjusted so that the first forward cable C1ais inserted through the shaft102by a first adjacent idler pulley P12athat is adjacent to the first idler pulley P11aand has a rotation axis parallel to the first axis. After inserted through the shaft102, the first forward cable C1ais then wound around the first motor capstan MC1via an idler pulley P13aas shown inFIG.5.

Meanwhile, the first backward cable C1bis pulled in a direction orthogonal to the second axis. However, the direction of the cable C1bis switched to a direction orthogonal to the first axis by a first idler pulley P11bthat uses the first axis as its rotation axis, and further, the layout is adjusted so that the first backward cable C1bis inserted through the shaft102by a first adjacent idler pulley P12bthat is adjacent to the first idler pulley P11band has a rotation axis parallel to the first axis. After inserted through the shaft102, the first backward cable C1bis then wound around the first motor capstan MC1via an idler pulley P13bfrom the opposite direction to the first forward cable C1a, as shown inFIG.5.

In short, the set of first forward and backward cables C1aand C1bis laid out so as to perform power transmission between the first jaw capstan JC1and the first motor capstan MC1by the cable loop method. Accordingly, as can also be seen fromFIG.8, the first motor capstan MC1is rotated by the first motor M1, so that the rotation of the first jaw capstan JC1can adjust the turning angle of the first jaw member J1about the second axis.

Also, as shown inFIGS.2,3, and6, the second forward cable C2ais pulled in a direction orthogonal to the second axis. However, the direction of the cable C2ais switched to a direction orthogonal to the first axis by a second idler pulley P21athat uses the first axis as its rotation axis, and further, the layout is adjusted so that the second forward cable C2ais inserted through the shaft102by a second adjacent idler pulley P22athat is adjacent to the second idler pulley P21aand has a rotation axis parallel to the first axis. After inserted through the shaft102, the second forward cable C2ais then wound around the second motor capstan MC2via an idler pulley P23aas shown inFIG.5.

Meanwhile, the second backward cable C2bis pulled in a direction orthogonal to the second axis. However, the direction of the cable C2bis switched to a direction orthogonal to the first axis by a second idler pulley P21bthat uses the first axis as its rotation axis, and further, the layout is adjusted so that the second backward cable C2bis inserted through the shaft102by a second adjacent idler pulley P22bthat is adjacent to the second idler pulley P21band has a rotation axis parallel to the first axis. After inserted through the shaft102, the first backward cable C1bis then wound around the second motor capstan MC2via an idler pulley P23bfrom the opposite direction to the second forward cable C2a, as shown inFIG.5.

In short, the set of second forward and backward cables C2aand C2bis laid out so as to perform power transmission between the second jaw capstan JC2and the second motor capstan MC2by the cable loop method. Accordingly, as can also be seen fromFIG.8, the second motor capstan MC2is rotated by the second motor M2, so that the rotation of the second jaw capstan JC2can adjust the turning angle of the second jaw member J2about the second axis.

The tractive force of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bis controlled by the first motor M1and the second motor M2so that a change is caused in the difference between the angles of the first jaw member J1and the second jaw member J2about the second axis. Thus, an opening and closing operation of the end effector formed with the pair of jaw members J1and J2can be performed. The open-close angle is determined by the difference between the angles of the first jaw member J1and the second jaw member J2about the second axis.

Also, the tractive force of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bis controlled by the first motor M1and the second motor M2so that a change is caused in the sum of the angles of the first jaw member J1and the second jaw member J2about the second axis. Thus, the end effector can be made to turn about the second axis. The average value of the angles of the first jaw member J1and the second jaw member J2about the second axis is the turning angle of the end effector about the second axis.

Meanwhile, the first motor M1, together with the first motor capstan MC1and each of the idler pulleys P13aand P13b, is secured to the first slide base SB1. Also, the second motor M2, together with the second motor capstan MC2and each of the idler pulleys P23aand P23b, is secured to the first slide base SB1. Further, the third forward cable C3ais joined to the first slide base SB1via the idler pulley P3a. Also, the third backward cable C3bis joined to the second slide base SB2via the third idler pulley P3b.

Note that the third forward cable C3ain the section from the first slide base SB1to the third idler pulley P3a, and the third backward cable C3bin the section from the second slide base SB2to the third idler pulley P3bare preferably laid out so as to be parallel to the longitudinal axis of the shaft102.

In short, the set of third forward and backward cables C3aand C3bis laid out so as to perform power transmission between the third motor capstan MC3, and the first and second slide bases SB1and SB2. Accordingly, as can be seen fromFIG.9, when the third motor capstan MC3is rotated by the third motor M3, the first slide base SB1and the second slide base SB2can be moved forward and backward in opposite directions in the longitudinal axis direction of the shaft102.

Referring toFIGS.6and8, the set of second forward and backward cables C2aand C2bis wound around the second idler pulleys P21aand P21b, from the opposite direction to the direction in which the set of first forward and backward cables C1aand C1ais wound around the first idler pulleys P11aand P11b. Therefore, when the set of first forward and backward cables C1aand C1ais moved backward and when the set of second forward and backward cables C2aand C2ais moved backward, rotative forces in opposite directions about the first axis are applied to the wrist element WE. Accordingly, when the first slide base SB1is moved forward to the end (which is the distal end) of the shaft102, and the second slide base SB2is moved backward to the root side (which is the proximal end) of the shaft102, the set of first forward and backward cables C1aand C1amoves forward, and the set of second forward and backward cables C2aand C2bmoves backward. As a result, the wrist element WE rotates in the positive direction about the first axis. Conversely, when the first slide base SB1is moved backward, and the second slide base SB2is moved forward, the set of first forward and backward cables C1aand C1amoves backward, and the set of second forward and backward cables C2aand C2bmoves forward. As a result, the wrist element WE rotates in the negative direction about the first axis. Here, it is assumed that both the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bhave a constant total length.

FIGS.10to12each show a state in which the wrist element WE is turned about the first axis by drive of the third motor M3. As can be seen fromFIGS.10to12, by the drive of the third motor M3, the first slide base SB1on which the first motor M1is mounted, and the second slide base SB2on which the second motor M2is mounted move forward and backward in the longitudinal axis direction of the shaft102.

By rotational drive of the third motor M3, the second slide base SB2is pulled with the backward cable C3b, and is moved backward to the proximal end side in the longitudinal axis direction of the shaft102. The wrist element WE is then pulled by the set of second forward and backward cables C2aand C2b, and rotates 80 degrees about the first axis as shown inFIG.10.

Further, in a case where the positions of the first slide base SB1and the second slide base SB2in the longitudinal axis direction of the shaft102are the same, the rotational position of the wrist element WE about the first axis is 0 degrees, as shown inFIG.11.

Also, by rotational drive of the third motor M3in the opposite direction, the first slide base SB1is pulled with the forward cable C3a, and is moved backward to the proximal end side in the longitudinal axis direction of the shaft102. The wrist element WE is then pulled by the set of first forward and backward cables C1aand C1b, and rotates −80 degrees about the first axis as shown inFIG.12.

In this manner, the third motor M3pulls the set of third forward and backward cables C3aand C3b, and the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bare moved forward and backward through sliding operations of the first slide base SB1and the second slide base SB2. Thus, the wrist element WE can be turned about the first axis. Furthermore, when the wrist element WE is turned about the first axis, the pre-tension of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bdoes not change.

The operation methods in the surgical tool unit end portion101are summarized below.

Operation at the First Axis:

When the third motor capstan MC3is rotated by the third motor M3, a tractive force is generated in one cable of the set of third forward and backward cables C3aand C3b. As a result, as shown inFIGS.10to12, the wrist element WE and the end effector mounted on the wrist element WE can be rotated in the positive direction or the reverse direction about the first axis.

Operation at the Second Axis:

The average value of the angle of the first jaw member J1about the second axis and the angle of the second jaw member J2about the second axis is defined as the angle of the end effector about the second axis. When the first jaw capstan JC1and the second jaw capstan JC2are rotated in the same direction and at the same speed, a turning operation of the end effector about the second axis is caused.

Operation of the End Effector:

The end effector is formed with a pair of opposing jaw members: the first jaw member J1and the second jaw member J2(seeFIG.2, for example). The open angle of the first jaw member J1and the second jaw member J2is set as the open-close angle of the end effector. When the first motor capstan MC1and the second motor capstan MC2are rotated in opposite directions at the same speed, an opening and closing operation of the end effector is caused.

Next, the relationship between operations of the first to third motors M1to M3and operations of the surgical tool unit end portion101is described.

FIG.13shows an example operation of the wrist element WE about the first axis. Here, the drawing is a view of the surgical tool unit end portion101as viewed from a direction parallel to the first axis. As shown in the drawing, the radius of each of the idler pulleys P11a, P11b, P21a, and P21bthat rotate about the first axis is represented by Rψ, and the turning angle of the wrist element WE about the first axis is ψ.

Further,FIG.14shows an example operation of the end effector about the second axis. Here, the drawing is a view of the surgical tool unit end portion101as viewed from a direction parallel to the second axis. As shown in the drawing, the pulley radius of the first jaw capstan JC1is represented by RJC1the pulley radius of the second jaw capstan JC2is RJC2, the turning angle of the first jaw member J1about the second axis is θj1, the turning angle of the second jaw member J2about the second axis is θj2, the open angle of the end effector is α, and the turning angle of the end effector about the second axis is θ.

Further, although not shown in the drawing, the pulley radius of the first motor capstan MC1is represented by RMC1, the pulley radius of the second motor capstan MC2is RMC2, the pulley radius of the third motor capstan MC3is RMC3, the rotation angle of the first motor capstan MC1is σMC1, the rotation angle of the second motor capstan MC2is σMC2, and the rotation angle of the third motor capstan MC3is σMC3.

Here, the turning angle ψ of the wrist element WE about the first axis, the turning angle θ of the end effector about the second axis, and the open angle α of the end effector are expressed as in the following Equations (1) to (3), respectively.

[Mathematical⁢Formula⁢1]ψ=RMC⁢3Rψ⁢ϕMC⁢3(1)[Mathematical⁢Formula⁢2]θ=θj⁢1+θj⁢22(2)[Mathematical⁢Formula⁢3]α=θj⁢1-θj⁢2(3)

Meanwhile, the turning angle θj1of the first jaw member J1about the second axis, and the turning angle θj2of the second jaw member J2about the second axis are expressed as in the following Equations (4) and (5), respectively.

[Mathematical⁢Formula⁢4]θj⁢1=RMC⁢1RJC⁢1⁢ϕMC⁢1(4)[Mathematical⁢Formula⁢5]θj⁢2=RMC⁢2RJC⁢2⁢ϕMC⁢2(5)

As can be seen from the above Equations (1) to (5), the turning angle ψ of the wrist element WE about the first axis, the turning angle θ of the end effector about the second axis, and the open angle α of the end effector can be independently driven without affecting one another. Thus, the surgical tool unit100has a structure that does not cause cross-axis interference.

Next, the range of movement of the surgical tool unit end portion101is described.

FIGS.15to22show examples of turning operations of the wrist element WE about the first axis, turning operations of the end effector about the second axis, and opening and closing operations of the end effector.

FIG.15shows a state in which the turning angle ψ of the wrist element WE about the first axis is 0 degrees, the turning angle θ of the end effector about the second axis is 0 degrees, and the open angle α of the end effector is 15 degrees. Further,FIG.16shows a state in which ψ is 0 degrees, θ is 80 degrees, and a is 15 degrees. Further,FIG.17shows a state in which ψ is 0 degrees, θ is 80 degrees, and a is 0 degrees. Further,FIG.18shows a state in which ψ is 0 degrees, θ is −80 degrees, and a is 15 degrees. Further,FIG.19shows a state in which ψ is −80 degrees, θ is 80 degrees, and a is 15 degrees. Further,FIG.20shows a state in which ψ is 80 degrees, θ is 80 degrees, and a is 15 degrees. Further,FIG.21shows a state in which ψ is −45 degrees, θ is −45 degrees, and a is 0 degrees. Further,FIG.22shows a state in which ψ is 80 degrees, θ is −80 degrees, and a is 0 degrees.

As can be seen fromFIGS.15to22, in the surgical tool unit end portion101, the wrist element WE has a degree of freedom of ±80 degrees about the first axis, and the end effector has a degree of freedom of ±80 degrees about the second axis.

C. Example Configuration (2) of a Surgical Tool UnitFIG.23shows another example configuration of a surgical tool unit to which the technology according to the present disclosure is applied. A surgical tool unit2300shown in the drawing includes a hollow shaft2302having a longitudinal axis, a surgical tool unit end portion2301at one end of the shaft2302, and a surgical tool unit drive unit2303at the other end of the shaft2302. The surgical tool unit end portion2301includes a wrist element capable of turning about a first axis parallel to the yaw axis with respect to the shaft2302, and an end effector at the end of the wrist element. The end effector performs an opening and closing operation with a second axis functioning as the open-close shaft, the second axis being parallel to the pitch axis. The end effector is formed with a pair of opposing jaw members that turn about the second axis and perform an opening and closing operation. However, the second axis is located at a position offset from the first axis. Meanwhile, the surgical tool unit drive unit2303includes two actuators that drive the respective jaw members in the surgical tool unit end portion2301, and one actuator that drives the wrist.

FIGS.24and25show the surgical tool unit drive unit2303in an enlarged manner (however, the viewing direction is different betweenFIGS.24and25). Further,FIG.26shows an example degree-of-freedom configuration of the surgical tool unit2300. Furthermore,FIG.27shows a six-sided view of the surgical tool unit2300. Note that the configuration of the surgical tool unit end portion2301is similar to that of the surgical tool unit end portion2301shown inFIGS.2and3, and therefore, is not shown in these drawings.

Referring toFIG.26, the surgical tool unit end portion2301includes a wrist element WE and an open-close end effector. The end effector includes a pair of opposing jaw members: a first jaw member J1and a second jaw member J2. The first jaw member J1is supported by the wrist element WE at a portion near the base, so as to be able to turn about the second axis. Likewise, the second jaw member J2is supported by the wrist element WE at a portion near the base, so as to be able to turn about the second axis.

A first jaw capstan JC1having the above-mentioned second axis as its rotation axis is provided near the root of the first jaw member J1. The set of first forward and backward cables C1aand C1bis wound around the first jaw capstan JC1. Also, a second jaw capstan JC2having the above-mentioned second axis as its rotation axis is provided near the root of the second jaw member J2. The set of second forward and backward cables C2aand C2bis wound around the second jaw capstan JC2.

The first forward cable C1ais pulled in a direction orthogonal to the second axis. However, the direction of the cable C1ais switched to a direction orthogonal to the first axis by a first idler pulley P11athat uses the first axis as its rotation axis, and further, the layout is adjusted so that the first forward cable C1ais inserted through the shaft2302by a first adjacent idler pulley P12athat is adjacent to the first idler pulley P11aand has a rotation axis parallel to the first axis. Also, the direction of the first backward cable C1bis switched from a direction orthogonal to the second axis to a direction orthogonal to the first axis by a first idler pulley P11bthat uses the first axis as its rotation axis, and further, the layout is adjusted so that the first backward cable C1bis inserted through the shaft2302by a first adjacent idler pulley P12bthat is adjacent to the first idler pulley P11band has a rotation axis parallel to the first axis.

Meanwhile, the second forward cable C2ais pulled in a direction orthogonal to the second axis. However, the direction of the cable C2ais switched to a direction orthogonal to the first axis by a second idler pulley P21athat uses the first axis as its rotation axis, and further, the layout is adjusted so that the second forward cable C2ais inserted through the shaft2302by a second adjacent idler pulley P22athat is adjacent to the second idler pulley P21aand has a rotation axis parallel to the first axis. Also, the direction of the second backward cable C2bis switched from a direction orthogonal to the second axis to a direction orthogonal to the first axis by a first idler pulley P11b, and further, the layout is adjusted so that the second backward cable C2bis inserted through the shaft2302by a second adjacent idler pulley P22bthat is adjacent to the second idler pulley P21band has a rotation axis parallel to the first axis.

Next, the side of the surgical tool unit drive unit2303is described, with reference toFIGS.24to26.

The surgical tool unit drive unit2303includes a first motor M1to be used for driving the first jaw member J1, a second motor M2to be used for driving the second jaw member J2, and a third motor M3to be used for driving the wrist element WE (seeFIGS.24,25, and26, for example). Further, first to third motor capstans MC1, MC2, and MC3as drive capstans are attached to the respective output shafts of the first to third motors M1to M3(seeFIG.26, for example). Although a rotary motor is assumed to be used for each of the first to third motors M1to M3, a motor with a speed reducer may also be used.

The set of first forward and backward cables C1aand C1bis wound around the first motor capstan MC1. That is, the layout is designed so that power transmission between the first jaw capstan JC1and the first motor capstan MC1is performed by the cable loop method. Accordingly, the first motor capstan MC1is rotated by the first motor M1, so that the rotation of the first jaw capstan JC1can adjust the turning angle of the first jaw member J1about the second axis.

Also, the set of second forward and backward cables C2aand C2bis wound around the second motor capstan MC2. That is, the layout is designed so that power transmission between the second jaw capstan JC2and the second motor capstan MC2is performed by the cable loop method. Accordingly, the second motor capstan MC2is rotated by the first motor M2, so that the rotation of the second jaw capstan JC2can adjust the turning angle of the second jaw member J2about the second axis.

As already described with reference toFIGS.2and3, each of the first jaw member J1and the second jaw member J2is turned about the second axis so that a change is caused in the difference between the angles of the first jaw member J1and the second jaw member J2about the second axis. Thus, the end effector is opened and closed. Further, the first jaw member J1and the second jaw member J2are simultaneously turned about the second axis so that a change is caused in the sum of the angles of the first jaw member J1and the second jaw member J2about the second axis. Thus, the end effector formed with the first jaw member J1and the second jaw member J2is turned about the second axis.

Referring toFIGS.24and25, each of the first to third motors M1to M3is secured onto a base B integrated with an end (the proximal end) of the shaft2302. Further, a set of third forward and backward cables C3aand C3bis wound around the third motor capstan MC3via third idler pulleys P3aand P3b. The other end of the third forward cable C3ais secured to a first slide base SB1that slides in the longitudinal axis direction of the shaft102. Also, the other end of the third backward cable C3bis secured to a second slide base SB2that slides in the longitudinal axis direction of the shaft102.

In short, the set of third forward and backward cables C3aand C3bis laid out so as to perform power transmission between the third motor capstan MC3, and the first and second slide bases SB1and SB2. Accordingly, when the third motor capstan MC3is rotated by the third motor M3, the first slide base SB1and the second slide base SB2can be moved forward and backward in opposite directions in the longitudinal axis direction of the shaft102.

Note that the third forward cable C3ain the section from the first slide base SB1to the third idler pulley P3a, and the third backward cable C3bin the section from the second slide base SB2to the third idler pulley P3bare preferably laid out so as to be parallel to the longitudinal axis of the shaft102.

As can be seen fromFIGS.24to26, the first forward cable C1ais wound around the first motor capstan MC1, via an idler pulley P14aon the first slide base SB1. The first backward cable C1bis wound around the first motor capstan MC1from the opposite direction to the first forward cable C1a, via an idler pulley P14bon the first slide base SB1. Therefore, when the first slide base SB1is made to move backward to the root side (which is the proximal end) of the shaft2302, the idler pulleys P14aand P14balso move backward. Accordingly, the set of first forward and backward cables C1aand C1bis pulled toward the proximal end side, and a rotation torque acts on the first jaw member J1.

Also, the second forward cable C2ais wound around the second motor capstan MC2, via an idler pulley P24aon the second slide base SB2. The second backward cable C2bis wound around the second motor capstan MC2from the opposite direction to the second forward cable C2a, via an idler pulley P24bon the second slide base SB2. Therefore, when the second slide base SB2is made to move backward, the idler pulleys P24aand P24balso move backward. Accordingly, the set of second forward and backward cables C2aand C2bis pulled toward the proximal end side, and a rotation torque acts on the second jaw member J2.

When the first slide base SB1is moved forward, and the second slide base SB2is moved backward, the set of first forward and backward cables C1aand C1amoves forward, and the set of second forward and backward cables C2aand C2bmoves forward. As a result, the wrist element WE rotates in the positive direction about the first axis. Conversely, when the first slide base SB1is moved backward, and the second slide base SB2is moved forward, the set of first forward and backward cables C1aand C1amoves backward, and the set of second forward and backward cables C2aand C2bmoves forward. As a result, the wrist element WE rotates in the negative direction about the first axis. Here, it is assumed that both the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bhave a constant total length.

FIGS.28to30each show a state in which the wrist element WE is turned about the first axis by drive of the third motor M3. As can be seen fromFIGS.28to30, by the drive of the third motor M3, the first slide base SB1and the second slide base SB2move forward and backward in the longitudinal axis direction of the shaft2302, and pull each cable of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b. However, being secured onto the base B, the first motor M1and the second motor M2do not slide.

By rotational drive of the third motor M3, the second slide base SB2is pulled with the third backward cable C3b, and is moved backward to the proximal end side in the longitudinal axis direction of the shaft2302. The wrist element WE is then pulled by the set of second forward and backward cables C2aand C2b, and rotates 80 degrees about the first axis as shown inFIG.28.

Further, in a case where the positions of the first slide base SB1and the second slide base SB2in the longitudinal axis direction of the shaft102are the same, the rotational position of the wrist element WE about the first axis is 0 degrees, as shown inFIG.29.

Also, by rotational drive of the third motor M3in the opposite direction, the first slide base SB1is pulled with the third forward cable C3a, and is moved backward to the proximal end side in the longitudinal axis direction of the shaft2302. The wrist element WE is then pulled by the set of first forward and backward cables C1aand C1b, and rotates −80 degrees about the first axis as shown inFIG.30.

In this manner, the third motor M3pulls the set of third forward and backward cables C3aand C3b, and the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bare moved forward and backward through sliding operations of the first slide base SB1and the second slide base SB2. Thus, the wrist element WE can be turned about the first axis. Furthermore, when the wrist element WE is turned about the first axis, the pre-tension of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bdoes not change.

The surgical tool unit2300differs from the surgical tool unit100shown inFIGS.1to22in that both the first motor M1and the second motor M2are secured to the base, and do not slide during a turning operation of the wrist element WE about the first axis. Thus, inertia of the structure during a sliding operation can be lowered.

The operation methods in the surgical tool unit end portion2301are summarized below.

Operation at the First Axis:

When the third motor capstan MC3is rotated by the third motor M3, a tractive force is generated in one cable of the set of third forward and backward cables C3aand C3b. As a result, the wrist element WE and the end effector mounted on the wrist element WE can be rotated in the positive direction or the reverse direction about the first axis.

Operation at the Second Axis:

The average value of the angle of the first jaw member J1about the second axis and the angle of the second jaw member J2about the second axis is defined as the angle of the end effector about the second axis. When the first jaw capstan JC1and the second jaw capstan JC2rotate in the same direction and at the same speed, a turning operation of the end effector about the second axis is caused.

Operation of the End Effector:

The end effector is formed with a pair of opposing jaw members: the first jaw member J1and the second jaw member J2(seeFIG.2, for example). The open angle of the first jaw member J1and the second jaw member J2is set as the open-close angle of the end effector. When the first motor capstan MC1and the second motor capstan MC2are rotated in opposite directions at the same speed, an opening and closing operation of the end effector is caused.

Next, the relationship between operations of the first to third motors M1to M3and operations of the surgical tool unit end portion2301is described.

As shown inFIG.13, the wrist element WE turns about the first axis. As shown in the drawing, the radius of each of the idler pulleys P11a, P11b, P21a, and P21bthat rotate about the first axis is represented by Rψ, and the turning angle of the wrist element WE about the first axis is ψ.

Further, as shown inFIG.14, the first jaw member J1and the second jaw member J2each turn about the second axis, so that a turning operation and an opening and closing operation of the end effector are performed. The pulley radius of the first jaw capstan JC1is represented by RJC1, the pulley radius of the second jaw capstan JC2is RJC2, the turning angle of the first jaw member J1about the second axis is θj1, the turning angle of the second jaw member J2about the second axis is θj2, the open angle of the end effector is α, and the turning angle of the end effector about the second axis is θ.

Further, although not shown in the drawing, the pulley radius of the first motor capstan MC1is represented by RMC1, the pulley radius of the second motor capstan MC2is RMC2, the pulley radius of the third motor capstan MC3is RMC3, the rotation angle of the first motor capstan MC1is σMC1, the rotation angle of the second motor capstan MC2is σMC2, and the rotation angle of the third motor capstan MC3is σMC3.

Here, the turning angle ψ of the wrist element WE about the first axis, the turning angle θ of the end effector about the second axis, and the open angle α of the end effector are expressed as in the following Equations (6) to (8), respectively.

[Mathematical⁢Formula⁢6]ψ=2⁢RMC⁢3Rψ⁢ϕMC⁢3(6)[Mathematical⁢Formula⁢7]θ=θj⁢1+θj⁢22(7)[Mathematical⁢Formula⁢8]α=θj⁢1-θj⁢2(8)

A result of comparison between Equation (6) and Equation (1) relating to the surgical tool unit100shows that, in the case of the surgical tool unit2300, the turning angle ψ of the wrist element WE about the first axis is twice the amount of rotation of the third motor M3. Therefore, the resolution of rotation about the first axis is lowered to ½. This is because the idler pulleys P14aand P14bsecured to the first slide base SB1, and the idler pulleys P24aand P24bsecured to the second slide base SB2operate as moving pulleys.

Meanwhile, the turning angle θj1of the first jaw member J1about the second axis, and the turning angle θj2of the second jaw member J2about the second axis are expressed as in the following Equations (9) and (10), respectively.

[Mathematical⁢Formula⁢9]θj⁢1=RMC⁢1RJC⁢1⁢ϕMC⁢1(9)[Mathematical⁢Formula⁢10]θj⁢2=RMC⁢2RJC⁢2⁢ϕMC⁢2(10)

As can be seen from the above Equations (6) to (10), the turning angle ψ of the wrist element WE about the first axis, the turning angle θ of the end effector about the second axis, and the open angle α of the end effector can be independently driven without affecting one another. Thus, it can be said that the surgical tool unit2300has a structure that does not cause cross-axis interference.

Furthermore, in the surgical tool unit end portion2301, a turning operation of the wrist element WE about the first axis, a turning operation of the end effector about the second axis, and an opening and closing operation of the end effector are performed, as shown inFIGS.15to22.

D. Example Configuration (3) of a Surgical Tool UnitFIG.31shows yet another example configuration of a surgical tool unit to which the technology according to the present disclosure is applied. A surgical tool unit3100shown in the drawing includes a hollow shaft3102having a longitudinal axis, a surgical tool unit end portion3101at one end of the shaft3102, and a surgical tool unit drive unit3103at the other end of the shaft3102. The surgical tool unit end portion3101includes a wrist element capable of turning about a first axis parallel to the yaw axis with respect to the shaft3102, and an end effector at the end of the wrist element. The end effector performs an opening and closing operation with a second axis functioning as the open-close shaft, the second axis being parallel to the pitch axis. The end effector is formed with a pair of opposing jaw members that turn about the second axis and perform an opening and closing operation. However, the second axis is located at a position offset from the first axis. Meanwhile, the surgical tool unit drive unit3103includes two actuators that drive the respective jaw members in the surgical tool unit end portion3101, and one actuator that drives the wrist.

FIGS.32and33show the surgical tool unit end portion3101in an enlarged manner (however, the viewing direction is different betweenFIGS.32and33). Also,FIGS.34and35show the surgical tool unit drive unit3103in an enlarged manner (however, the viewing direction is different betweenFIGS.34and35). Further,FIG.36shows an example degree-of-freedom configuration of the surgical tool unit3100. Furthermore,FIG.37shows a six-sided view of the surgical tool unit3100.

The surgical tool unit end portion3101includes a wrist element WE and an open-close end effector. The end effector includes a pair of opposing jaw members: a first jaw member J1and a second jaw member J2(seeFIGS.32and33, for example). The wrist element WE is supported at a portion near the root so as to be able to turn about the first axis parallel to the yaw axis at the end (distal end) of the shaft3102. Further, the first jaw member J1and the second jaw member J2that constitute the end effector are supported so as to be able to turn about the second axis parallel to the pitch axis at the end of the wrist element WE. The first jaw member J1and the second jaw member J2open and close when the open angle with the second axis serving as the open-close shaft changes.

Meanwhile, the surgical tool unit drive unit3103includes a first motor M1to be used for driving the first jaw member J1, a second motor M2to be used for driving the second jaw member J2, and a third motor M3to be used for driving the wrist element WE (seeFIGS.34,35, and36, for example). Each of the first to third motors M1to M3is secured onto a base B1integrated with an end (the proximal end) of the shaft3102. Further, first to third motor capstans MC1, MC2, and MC3as drive capstans are attached to the output shafts of the first to third motors M1to M3, respectively. Although a rotary motor is assumed to be used for each of the first to third motors M1to M3, a motor with a speed reducer may also be used.

Referring toFIGS.34and35, a first slide base SB1and a second slide base SB2that slide in the longitudinal axis direction of the shaft3102are attached to each side surface of the base B1.

Referring toFIGS.32,33, and36, a first jaw capstan JC1having the second axis as its rotation axis is provided near the root of the first jaw member J1. The set of first forward and backward cables C1aand C1bis wound around the first jaw capstan JC1. Also, referring toFIGS.34to36, the set of first forward and backward cables C1aand C1bis wound around the first motor capstan MC1.

Referring toFIGS.32,33, and36, the first forward cable C1ais pulled in a direction orthogonal to the second axis. However, the direction of the cable C1ais switched to a direction orthogonal to the first axis by a first idler pulley P11athat uses the first axis as its rotation axis, and further, the layout is adjusted so that the first forward cable C1ais inserted through the shaft3102by a first adjacent idler pulley P12athat is adjacent to the first idler pulley P11aand has a rotation axis parallel to the first axis. After inserted through the shaft3102, the first forward cable C1ais then wound around the first motor capstan MC1via an idler pulley P14asecured to the first slide base SB1and an idler pulley P13asecured to the base B1, as shown inFIGS.34and35.

Meanwhile, the first backward cable C1bis pulled in a direction orthogonal to the second axis. However, the direction of the cable C1bis switched to a direction orthogonal to the first axis by a first idler pulley P11bthat uses the first axis as its rotation axis, and further, the layout is adjusted so that the first backward cable C1bis inserted through the shaft3102by a first adjacent idler pulley P12bthat is adjacent to the first idler pulley P11band has a rotation axis parallel to the first axis. After inserted through the shaft3102, the first backward cable C1bis then wound around the first motor capstan MC1from the opposite direction to the first forward cable C1avia an idler pulley P14bsecured to the first slide base SB1and an idler pulley P13bsecured to the base B1, as shown inFIGS.34and35.

Accordingly, the first motor capstan MC1is rotated by the first motor M1, so that a tractive force is generated in the set of first forward and backward cables C1aand C1b. Thus, the rotation of the first jaw capstan JC1can adjust the turning angle of the first jaw member J1about the second axis. As the first jaw member J1is driven by the cable loop method using the set of first forward and backward cables C1aand C1b, it is possible to make the range of movement of the first jaw member J1wider.

Referring toFIGS.32,33, and36, a second jaw capstan JC2having the second axis as its rotation axis is provided near the root of the second jaw member J2. The set of second forward and backward cables C2aand C2bis wound around the second jaw capstan JC2. Also, referring toFIGS.34to36, the set of second forward and backward cables C2aand C2bis wound around the second motor capstan MC2.

Referring toFIGS.32,33, and36, the second forward cable C2ais pulled in a direction orthogonal to the second axis. However, the direction of the cable C2ais switched to a direction orthogonal to the first axis by a second idler pulley P21athat uses the first axis as its rotation axis, and further, the layout is adjusted so that the second forward cable C2ais inserted through the shaft3102by a second adjacent idler pulley P22athat is adjacent to the second idler pulley P21aand has a rotation axis parallel to the first axis. After inserted through the shaft3102, the second forward cable C2ais then wound around the second motor capstan MC2via an idler pulley P24asecured to the second slide base SB2and an idler pulley P23asecured to the base B1, as shown inFIGS.34and35.

Meanwhile, the second backward cable C2bis pulled in a direction orthogonal to the second axis. However, the direction of the cable C2bis switched to a direction orthogonal to the first axis by a second idler pulley P21bthat uses the first axis as its rotation axis, and further, the layout is adjusted so that the second backward cable C2bis inserted through the shaft3102by a first adjacent idler pulley P22bthat is adjacent to the second idler pulley P21band has a rotation axis parallel to the first axis. After inserted through the shaft3102, the second backward cable C2bis then wound around the second motor capstan MC2from the opposite direction to the second forward cable C2avia an idler pulley P24bsecured to the second slide base SB2and an idler pulley P23bsecured to the base B1, as shown inFIGS.34and35.

Accordingly, the second motor capstan MC2is rotated by the second motor M2, so that a tractive force is generated in the set of second forward and backward cables C2aand C2b. Thus, the rotation of the second jaw capstan JC2can adjust the turning angle of the second jaw member J2about the second axis. As the second jaw member J2is driven by the cable loop method using the set of second forward and backward cables C2aand C2b, it is possible to make the range of movement of the second jaw member J2wider.

Referring toFIGS.32,33, and36, a wrist capstan WC using the first axis as its rotation axis is provided near the root of the wrist element WE. The set of third forward and backward cables C3aand C3bis wound around the wrist capstan WC. Also, referring toFIGS.34to36, the set of third forward and backward cables C3aand C3bis wound around the third motor capstan MC3.

The tractive force of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bis controlled by the first motor M1and the second motor M2so that a change is caused in the difference between the angles of the first jaw member J1and the second jaw member J2about the second axis. Thus, an opening and closing operation of the end effector formed with the pair of jaw members J1and J2can be performed. The open-close angle is determined by the difference between the angles of the first jaw member J1and the second jaw member J2about the second axis.

Also, the tractive force of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bis controlled by the first motor M1and the second motor M2so that a change is caused in the sum of the angles of the first jaw member J1and the second jaw member J2about the second axis. Thus, the end effector can be made to turn about the second axis. The average value of the angles of the first jaw member J1and the second jaw member J2about the second axis is the turning angle of the end effector about the second axis.

Referring toFIGS.32,33, and36, the third forward cable C3ais wound around the wrist capstan WC, is pulled in a direction orthogonal to the first axis and in the longitudinal axis direction of the shaft3102, and is inserted through the shaft3102. After inserted through the shaft3102, the third forward cable C3ais then wound around the third motor capstan MC3via a third idler pulley P3asecured to the base B1, as shown inFIGS.34and35.

Meanwhile, the third backward cable C3bis wound around the wrist capstan WC from the opposite direction to the third forward cable C3a, is pulled in a direction orthogonal to the first axis and in the longitudinal axis direction of the shaft3102, and is inserted through the shaft3102. After inserted through the shaft3102, the third backward cable C3bis then wound around the third motor capstan MC3from the opposite direction to the third forward cable C3avia a third idler pulley P3bsecured to the base B1as shown inFIGS.34and35.

Accordingly, the third motor capstan MC3is rotated by the third motor M3, so that a tractive force is generated in the set of third forward and backward cables C3aand C3b. Thus, the rotation of the wrist capstan WC can adjust the turning angle of the wrist element WE about the first axis. As the wrist element WE is driven by the cable loop method using the set of third forward and backward cables C3aand C3b, it is possible to widen the range of movement of the wrist element WE.

Referring toFIGS.34to36, a set of fourth forward and backward cables C4aand C4bis wound around a fourth idler pulley P4secured to the base B1. Further, an end of the fourth forward cable C4ais secured to the first slide base SB1, and the fourth backward cable C4bis secured to the second slide base SB2.

As already described, both the first slide base SB1and the second slide base SB2slide on the base B1in the longitudinal axis direction of the shaft3102. Further, the idler pulleys P14aand P14baround which the set of first forward and backward cables C1aand C1bis wound are secured to the first slide base SB1, and the set of second forward and backward cables C2aand C2bis secured to the second slide base SB2.

The set of first forward and backward cables C1aand C1bis pulled by the first motor M1, when the first jaw member J1is turned about the second axis. Also, the set of second forward and backward cables C2aand C2bis pulled by the second motor M2, when the second jaw member J2is turned about the second axis. Here, when the wrist element WE is turned about the first axis, it is necessary to prevent a load from being applied onto the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b.

Therefore, the idler pulleys P14aand P14baround which the set of first forward and backward cables C1aand C1bis wound are secured to the first slide base SB1, and the idler pulleys P24aand P24baround which the set of second forward and backward cables C2aand C2bis wound are secured to the second slide base SB2. Further, the set of fourth forward and backward cables C4aand C4bhaving the respective ends secured to the first slide base SB1and the second slide base SB2is wound around the fourth idler pulley P4secured to the base B1. In this configuration, the first slide base SB1and the second slide base SB2move forward and backward in the longitudinal axis direction of the shaft3102, so that the positions of the idler pulleys P14aand P14band the idler pulleys P24aand P24bare appropriately adjusted. As a result, when the wrist element WE is turned about the first axis, it is possible to prevent a load from being applied onto the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b.

When a turning operation about the first axis is actively performed by the wrist element WE as the third motor M3rotates, the first slide base SB1and the second slide base SB2passively move forward and backward accordingly in the longitudinal direction of the shaft3102. Thus, the tension to be applied onto each cable of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bcan be kept constant.

The surgical tool unit3100is designed to directly rotate the wrist capstan WC with the third motor M3. Accordingly, it is possible to avoid the decrease in resolution of rotation about the first axis in the surgical tool unit2300shown inFIGS.23to30.

Further, like the surgical tool unit2300, the surgical tool unit3100has a structure in which both the first motor M1and the second motor M2are secured to the base, and do not slide during a turning operation of the wrist element WE about the first axis. Thus, inertia of the structure during a sliding operation can be lowered.

FIGS.38to40each show a state in which the wrist element WE is turned about the first axis by drive of the third motor M3. As can be seen fromFIGS.28to30, by the drive of the third motor M3, the first slide base SB1and the second slide base SB2move forward and backward in the longitudinal axis direction of the shaft2302, and pull each cable of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b. However, being secured onto the base B, the first motor M1and the second motor M2do not slide.

The surgical tool unit3100is designed to directly rotate the wrist capstan WC with the third motor M3. By rotational drive of the third motor M3, the wrist element WE is pulled with the third forward cable C3a, and rotates 80 degrees about the first axis as shown inFIG.38. At that time, the first slide base SB1moves forward in the longitudinal axis direction of the shaft3102, and the second slide base SB2moves backward. As a result, the positions of the idler pulleys P14aand P14band the idler pulleys P24aand P24bare appropriately adjusted, and a load can be prevented from being applied onto the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b.

Further, when the rotational position of the wrist element WE about the first axis is 0 degrees, the positions of the first slide base SB1and the second slide base SB2in the longitudinal axis direction of the shaft102are the same, as shown in FIG.39. As a result, the positions of the idler pulleys P14aand P14band the idler pulleys P24aand P24bare appropriately adjusted, and a load can be prevented from being applied onto the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b.

Also, by rotational drive of the third motor M3, the wrist element WE is pulled with the third forward cable C3a, and rotates −80 degrees about the first axis as shown inFIG.40. At that time, the second slide base SB2moves forward in the longitudinal axis direction of the shaft3102, and the first slide base SB1moves backward. As a result, the positions of the idler pulleys P14aand P14band the idler pulleys P24aand P24bare appropriately adjusted, and a load can be prevented from being applied onto the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2b.

As can be seen fromFIGS.38to40, the set of third forward and backward cables C3aand C3bis pulled by the third motor M3, so that the wrist element WE can be directly turned about the first axis. When the wrist element WE turns about the first axis, the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bthen move forward and backward in the longitudinal axis direction of the shaft3102. Thus, the pre-tension of the set of first forward and backward cables C1aand C1band the set of second forward and backward cables C2aand C2bdoes not change.

The operation methods in the surgical tool unit end portion3101are summarized below.

Operation at the First Axis:

When the third motor capstan MC3is rotated by the third motor M3, a tractive force is generated in one cable of the set of third forward and backward cables C3aand C3b. As a result, the wrist element WE and the end effector mounted on the wrist element WE can be rotated in the positive direction or the reverse direction about the first axis.

Operation at the Second Axis:

The average value of the angle of the first jaw member J1about the second axis and the angle of the second jaw member J2about the second axis is defined as the angle of the end effector about the second axis. When the first jaw capstan JC1and the second jaw capstan JC2rotate in the same direction and at the same speed, a turning operation of the end effector about the second axis is caused.

Operation of the End Effector:

The end effector is formed with a pair of opposing jaw members: the first jaw member J1and the second jaw member J2(seeFIG.32, for example). The open angle of the first jaw member J1and the second jaw member J2is set as the open-close angle of the end effector. When the first motor capstan MC1and the second motor capstan MC2are rotated in opposite directions at the same speed, an opening and closing operation of the end effector is caused.

E. Modifications of the Surgical Tool Unit

E-1. Modifications of the Method for Driving the Cables

It is most preferable to use electromagnetic rotary motors as the first to third motors M1to M3. However, it is also possible to use some other types of actuators capable of rotating the drive capstans. Examples of other modifications of the actuators that pull the cables may include the following.Piezoelectric linear-motion ultrasonic motorsPiezoelectric rotary ultrasonic motorsHydraulic linear motorsHydraulic rotary motorsPolymeric linear actuatorsElectromagnetic linear motorsShape-memory alloys

Further, regardless of which kind of actuator is adopted, the actuators may be equipped with a speed reducer, a position detector, and an emergency brake mechanism. Here, examples of the speed reducers include gear reducers, wave gear reducers, planetary gear reducers, paradox planetary gear reducers, cable reducers, traction reducers, ball screws, sliding screws, and worm gears. Further, examples of the position detectors include magnetic encoders, optical encoders, and potentiometers.

E-2. Modifications of the Shape of the Jaw Members

In each of the drawings, the first jaw member J1and the second jaw member J2are drawn in simple shapes for convenience sake. In practice, the shape of the jaw members may be changed depending on the purpose of use of the surgical tool unit. For example, the following forms can be adopted.ForcepsBipolar forcepsScissorsStaplers

E-3. Modifications of the Shaft

The shaft102is ideally a rigid body, but may have a flexible configuration. Further, in each drawing, the shaft102having a simple hollow cylindrical shape is shown for simplification. However, the shaft does not necessarily have a cylindrical shape. For example, a cross-section of the shaft102may have a polygonal shape or an elliptical shape, or its cross-sectional shape may change midway in the longitudinal axis direction. The same applies to the shafts2302and3102.

E-4. Modifications of the Cables

A cable may be a bundle of metallic wires, a bundle of resin, or a mixture of a plurality of materials such as metal wires and resin. Also, a shaft102formed with a metal having a high rigidity may be used at a cable portion that is disposed inside the shaft102or the like and does not need to be curved, and be connected to a flexible cable that is used at a portion having a curve. In this manner, one cable may be formed. Examples of substitutes for the cables include the following.Metallic or resin wiresWires obtained by weaving thin metallic or resin wires having a small diameter

E-5. Modifications of the Idler Pulleys

In the examples described above, idler pulleys are used for adjusting the layout of the cables. With the use of idler pulleys, the sliding friction at a time when the cables are pulled can be reduced, and a smooth operation can be performed. In a case where sliding friction is to be reduced, idler pulleys each having a rotational bearing may be used.

However, the use of idler pulleys adds to the size of the mechanism, and the number of components becomes larger. Therefore, to further reduce the size of the surgical tool unit end portion101, cables may be laid out along guide grooves formed in the mechanism without any idler pulley.

E-6. Sensing

To detect the tension of the cables, a strain sensor may be mounted on each cable. Examples of the strain sensor include a variable-resistance strain sensor and a fiber Bragg grating (FBG) strain sensor. Alternatively, a torque sensor may be mounted on the actuators that pull cables.

F. Example Applications of the Surgical Tool Unit

F-1. Example application to a computer-aided surgery systemFIG.41shows an example external configuration of a surgery support system4100(also referred to as a computer-aided surgery system or a robotically-assisted surgery system) using a surgical tool unit according to this embodiment. The surgery support system4100shown in the drawing includes an arm4101having a multi-link structure, and a surgical tool unit4102is attached to the end of the arm4101. The surgical tool unit4102may be replaceable. The surgery support system4100is used in laparoscopic surgery, for example, and the surgical tool unit end portion101is inserted into an abdominal cavity through a trocar (not shown), to perform an operation such as gripping and cutting of an affected part.

The surgery support system4100shown in the drawing may be used as the slave device in a master-slave robot, for example, and the arm4101and the surgical tool unit4102are driven in accordance with an instruction from the master device (not shown). Further, a bilateral control method is applied to this type of master-slave robot, for example. Furthermore, the surgery support system4100can also function as a surgical-tool-equipped arm when handled directly by the operator.

Note that the arm4101may be a robot of any mechanism type such as a polar-coordinate robot, a cylindrical coordinate robot, a Cartesian coordinate robot, a vertical articulated robot, a horizontal articulated robot, a parallel link robot, or a remote center of motion (RCM) robot.

Further, in a case where the surgery support system4100is a surgical robot that supports laparoscopic surgery, the arm4101is preferably a vertical articulated arm or a remote center of motion (RCM) arm that has its remote rotation center at a position away from the driving rotation center and performs a pivoting (fixed-point) motion, so as to achieve compactness of the mechanism, ease of a pivoting motion generation at the site of a trocar, and the like.

Furthermore, althoughFIG.41shows an example configuration of a computer-aided surgery system to which only one surgical tool unit can be attached, the present technology can also be applied to a computer-aided surgery system of a type to which a plurality of surgical tool units can be simultaneously attached to perform laparoscopic surgery.

F-2. Example Application to a Surgical Operating Unit

FIG.42shows an example external configuration of a surgical operating unit4200using a surgical tool unit according to this embodiment. The surgical operating unit4200includes a handle unit4201that is directly held and operated by a user (operator) by hand, and a surgical tool unit4202is attached to the end of the handle unit4201. The surgical tool unit4202may be replaceable.

The handle unit4201may include a joystick4203that can be handled with a thumb to designate a desired orientation of the posture of the surgical tool unit end portion of the surgical tool unit4202, for example. The handle unit4201may also include a button4204that can be pushed with an index finger to issue an instruction for an opening and closing operation of the jaw members.

A controller (not shown) is installed in the handle unit4201. The controller calculates the turning angle of the wrist element WE about the first axis, and the turning angle and the open angle of the end effector about the second axis, in accordance with the amount of operation of the joystick4203or the button4204. The controller then converts these angles into the amount of rotation of each motor, and outputs a control signal to the surgical tool unit drive unit103.

G. Effects

By the technology according to the present disclosure, operations with three degrees of freedom, which are a yaw operation, a pitch operation, and an opening and closing operation of the end effector at the end of a surgical tool, can be performed with three motors. Thus, the drive unit of the surgical tool can be made smaller in size.

Also, by the technology according to the present disclosure, a yaw operation, a pitch operation, and an opening and closing operation of the end effector at the end of a surgical tool can be performed with a structure that does not cause cross-axis interference. Thus, control on each axis becomes much easier.

INDUSTRIAL APPLICABILITY

The technology according to the present disclosure has been described in detail so far, with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications to and substitutions of the embodiments without departing from the scope of the technology according to the present disclosure.

In this specification, embodiments in which the technology according to the present disclosure is applied to a surgical tool to be used in a surgical robot have been mainly described. However, the subject matter of the technology according to the present disclosure is not limited to these embodiments. The technology according to the present disclosure can be applied to robots in various fields other than medical care, such as precision work robots. The technology according to the present disclosure can also be applied to a grip-type operating unit and a precision work device a user can operate while gripping it with a hand.

In short, the technology according to the present disclosure has been described through examples, and the descriptions in this specification should not be interpreted in a restrictive manner. The claims should be taken into account in understanding the subject matter of the technology according to the present disclosure.

Note that the technology according to the present disclosure may also be embodied in the configurations described below.

(1) A surgical tool including:a shaft;a wrist that is connected to an end of the shaft and is rotatable about a first axis;a first jaw member and a second jaw member that are supported rotatably about a second axis with respect to the wrist;a set of first forward and backward cables that transmits a force for turning the first jaw member about the second axis;a set of second forward and backward cables that transmits a force for turning the second jaw member about the second axis; anda turning motion unit that generates a turning motion of the wrist about the first axis so that pre-tension of the set of first forward and backward cables and the set of second forward and backward cables does not change.

(2) The surgical tool according to (1), further including:a first jaw capstan that is provided on the first jaw member and has a rotation axis that is the second axis, the set of first forward and backward cables being wound around the first jaw capstan; anda second jaw capstan that is provided on the second jaw member and has a rotation axis that is the second axis, the set of second forward and backward cables being wound around the second jaw capstan.

(3) The surgical tool according to (2), further including:a first idler pulley unit that switches the set of first forward and backward cables to a direction substantially parallel to a longitudinal axis of the shaft; anda second idler pulley unit that switches the set of second forward and backward cables to a direction substantially parallel to the longitudinal axis of the shaft.

(4) The surgical tool according to (3), in whichthe first idler pulley unit includes a first idler pulley that rotates about the first axis, and a first adjacent idler pulley that is adjacent to the first idler pulley and has a rotation axis parallel to the first axis, andthe second idler pulley unit includes a second idler pulley that rotates about the first axis, and a second adjacent idler pulley that is adjacent to the second idler pulley and has a rotation axis parallel to the first axis.

(5) The surgical tool according to (3) or (4), further including:a first actuator that rotates a first drive capstan and pulls the set of first forward and backward cables; anda second actuator that rotates a second drive capstan and pulls the set of second forward and backward cables.

(6) The surgical tool according to (5), in whichthe turning motion unit generates a turning motion of the wrist about the first axis by causing one of the set of first forward and backward cables and the set of second forward and backward cables to move backward and the other one to move forward in a longitudinal axis direction of the shaft.

(7) The surgical tool according to (6), in whichthe turning motion unit includes:a first slide base that secures the first actuator and the first drive capstan, and slides in the longitudinal axis direction of the shaft;a second slide base that secures the second actuator and the second drive capstan, and slides in the longitudinal axis direction of the shaft; anda forward and backward motion unit that causes the first slide base and the second slide base to move forward and backward in the longitudinal axis direction of the shaft, andgenerates a turning motion of the wrist about the first axis, on the basis of forward and backward motions of the first slide base and the second slide base.

(8) The surgical tool according to (6), in whichthe first actuator and the first drive capstan, and the second actuator and the second drive capstan are secured to the shaft, andthe turning motion unit includes:a first slide base that secures an idler pulley through which the set of first forward and backward cables is wound around the first drive capstan, and slides in the longitudinal axis direction of the shaft;a second slide base that secures an idler pulley through which the set of second forward and backward cables is wound around the second drive capstan, and slides in the longitudinal axis direction of the shaft; anda forward and backward motion unit that causes the first slide base and the second slide base to move forward and backward in the longitudinal axis direction of the shaft, and generates a turning motion of the wrist about the first axis, in accordance with forward and backward motions of the first slide base and the second slide base.

(9) The surgical tool according to (7) or (8), in whichthe forward and backward motion unit includes:a third actuator that rotates a third drive capstan; anda set of third forward and backward cables that is wound around the third drive capstan, the respective ends of the set of third forward and backward cables being secured to the first slide base and the second slide base, andgenerates forward and backward motions of the first slide base and the second slide base from rotation of the third drive capstan.

(10) The surgical tool according to (5), in whichthe first actuator and the first drive capstan, and the second actuator and the second drive capstan are secured to the shaft, andthe turning motion unit includes: a wrist capstan that is provided on the wrist and has a rotation axis that is the first axis, the set of third forward and backward cables being wound around the wrist capstan; a third actuator that rotates a third drive capstan and pulls the third cable set; and an adjustment unit that adjusts pre-tension of the set of first forward and backward cables and the set of second forward and backward cables, in accordance with a turning motion of the wrist about the first axis.

(11) The surgical tool according to (10), in whichthe adjustment unit includes:a first slide base that secures an idler pulley through which the set of first forward and backward cables is wound around the first drive capstan, and slides in a longitudinal axis direction of the shaft; anda second slide base that secures an idler pulley through which the set of second forward and backward cables is around the second drive capstan, and slides in the longitudinal axis direction of the shaft, andadjusts the pre-tension of the set of first forward and backward cables and the set of second forward and backward cables, by causing the first slide base and the second slide base to move forward and backward in accordance with a turning motion of the wrist about the first axis.

(12) The surgical tool according to (11), in whichthe adjustment unit further includes:a fourth idler pulley that is secured to the shaft; anda set of fourth forward and backward cables that is wound around the fourth idler pulley, the respective ends of the set of fourth forward and backward cables being secured to the first slide base and the second slide base, andadjusts the pre-tension force of the set of first forward and backward cables and the set of second forward and backward cables, by causing the first slide base and the second slide base to move forward and backward in accordance with a turning motion of the wrist about the first axis, using a tractive force of the set of fourth forward and backward cables.

(13) A surgery support system including a surgical tool, and an arm to which the surgical tool is attached,the surgical tool including:a shaft;a wrist that is connected to an end of the shaft and is rotatable about a first axis;a first jaw member and a second jaw member that are supported rotatably about a second axis with respect to the wrist;a set of first forward and backward cables that transmits a force for turning the first jaw member about the second axis;a set of second forward and backward cables that transmits a force for turning the second jaw member about the second axis; anda turning motion unit that generates a turning motion of the wrist about the first axis so that pre-tension of the set of first forward and backward cables and the set of second forward and backward cables does not change.

(14) A surgical operating unit including a surgical tool, and a handle unit to which the surgical tool is attached,the surgical tool including:a shaft;a wrist that is connected to an end of the shaft and is rotatable about a first axis;a first jaw member and a second jaw member that are supported rotatably about a second axis with respect to the wrist;a set of first forward and backward cables that transmits a force for turning the first jaw member about the second axis;a set of second forward and backward cables that transmits a force for turning the second jaw member about the second axis; anda turning motion unit that generates a turning motion of the wrist about the first axis so that pre-tension of the set of first forward and backward cables and the set of second forward and backward cables does not change.

REFERENCE SIGNS LIST

100Surgical tool unit101Surgical tool unit end portion102Shaft103Surgical tool unit drive unit2300Surgical tool unit2301Surgical tool unit end portion2302Shaft2303Surgical tool unit drive unit3100Surgical tool unit3101Surgical tool unit end portion3102Shaft3103Surgical tool unit drive unit4100Computer-aided surgery system4101Arm4102Surgical tool unit4200Surgical operating unit4201Handle unit4202Surgical tool unit4203Joystick4204Button