Actuator

Abstract

To provide an actuator that can maintain relatively high positional accuracy even when being replaced.SOLUTION: An actuator 1 includes: a housing 61a; a nut 63a stored in the housing 61a; a screw shaft 64a moving along an axis A1a relative to the housing 61a with the rotation of the nut 63a; a drive part 60a including a linear encoder 75a for detecting a travel amount of the screw shaft 64a; and a storage part 90 in which individual data relating to specification of the drive part 60a is stored.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to actuators. [Background technology]

[0002] Patent Document 1 discloses a surgery support device equipped with a robot arm. The robot arm holds tools such as forceps, an endoscope, and an electronic scalpel, and is operated by a doctor to support surgery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-65644 A Summary of the Invention [Problem to be solved by the invention]

[0004] A robot arm (actuator) that supports surgery requires relatively high positional accuracy. However, when an actuator is replaced, the position of the instrument after movement may differ before and after replacement due to individual differences in the actuator, even if the amount of operation by the doctor is the same. In this case, the positional accuracy may decrease.

[0005] An aspect of the present disclosure aims to provide an actuator that can maintain relatively high positional accuracy even when it is replaced. [Means for solving the problem]

[0006] An actuator according to one aspect of the present disclosure includes a housing, a nut accommodated in the housing, a screw shaft that moves relative to the housing along an axis as the nut rotates, a drive unit having a linear encoder that detects the amount of movement of the screw shaft, and a storage unit in which individual data regarding the specifications of the drive unit is stored.

[0007] According to this, the amount of movement of the screw shaft can be corrected based on the individual data, and therefore the actuator can maintain a relatively high positional accuracy even when it is replaced.

[0008] In the actuator according to one aspect of the present disclosure, the linear encoder is an incremental type linear encoder.

[0009] This makes it possible to reduce the cost of the linear encoder.

[0010] In an actuator according to one aspect of the present disclosure, the individual data includes a distance of a mounting position of a scale of the linear encoder relative to a reference mounting position in a direction along the axis.

[0011] The distance of the mounting position of the scale from a reference mounting position in the axial direction affects the position of the screw shaft, so by correcting the movement amount of the screw shaft based on the distance of the mounting position of the scale from a reference mounting position in the axial direction, the actuator can reliably maintain a relatively high positional accuracy even when it is replaced.

[0012] In an actuator according to one aspect of the present disclosure, the individual data includes a first tilt angle of a direction in which a scale of the linear encoder extends relative to a direction along the axis.

[0013] The first inclination angle of the direction in which the scale extends relative to the axis affects the position of the screw shaft, and therefore, by correcting the movement amount of the screw shaft based on the first inclination angle of the direction in which the scale extends relative to the axis, the actuator can reliably maintain a relatively high positional accuracy even when it is replaced.

[0014] In an actuator according to one aspect of the present disclosure, the individual data includes a distance between a predetermined portion of the screw shaft and a predetermined portion of the nut in a direction along the axis when the screw shaft is in a predetermined position.

[0015] The distance between a predetermined portion of the screw shaft and a predetermined portion of the nut affects the position of the screw shaft, so by correcting the amount of movement of the screw shaft based on the distance, the actuator can reliably maintain a relatively high positional accuracy even when it is replaced.

[0016] The actuator according to one aspect of the present disclosure further includes a guide member that guides the screw shaft along the axis, and the individual data includes a distance between a predetermined portion of the guide member and a predetermined portion of the housing in a direction along the axis when the screw shaft is in a predetermined position.

[0017] The distance between a predetermined portion of the guide member and a predetermined portion of the housing affects the position of the screw shaft, and therefore, by correcting the amount of movement of the screw shaft based on the distance, the actuator can reliably maintain a relatively high degree of positional accuracy even when it is replaced.

[0018] An actuator according to one embodiment of the present disclosure further includes a guide member that guides the screw shaft along the axis, the linear encoder includes a scale having a reference position and a head that detects the reference position, and the individual data includes a distance between a second predetermined portion of the guide member and a second predetermined portion of the housing in a direction along the axis when the screw shaft is at a predetermined position, and a distance between the head and the reference position.

[0019] The distance between the second predetermined portion of the guide member and the second predetermined portion of the housing, and the distance between the head and the reference position affect the position of the screw shaft, and therefore, by correcting the movement amount of the screw shaft based on these distances, the actuator can reliably maintain a relatively high positional accuracy even when it is replaced.

[0020] In the actuator according to one aspect of the present disclosure, the individual data includes a second inclination angle of a central axis line of the screw shaft relative to the axis line.

[0021] The second tilt angle affects the position of the screw shaft. Therefore, by correcting the movement amount of the screw shaft based on the second tilt angle, the actuator can reliably maintain a relatively high positional accuracy even when it is replaced.

[0022] In an actuator according to one aspect of the present disclosure, the storage section has an image of a two-dimensional code into which the individual data is converted.

[0023] This allows the storage section to be easily attached to the actuator, and also allows the storage section to be made smaller.

[0024] An actuator according to one embodiment of the present disclosure further includes a guide member that guides the screw shaft along the axis, the linear encoder includes a scale having a reference position and a head that detects the reference position, and the individual data includes a distance between a second predetermined portion of the guide member and a second predetermined portion of the housing in a direction along the axis when the head detects the reference position.

[0025] The distance between the second predetermined portion of the guide member and the second predetermined portion of the housing affects the position of the screw shaft, and therefore, by correcting the amount of movement of the screw shaft based on the distance, the actuator can reliably maintain a relatively high positional accuracy even when it is replaced.

[0026] The actuator according to one embodiment of the present disclosure includes five of the driving units and one of the storage units, and the one of the storage units stores individual data relating to specifications of each of the five driving units.

[0027] This allows costs to be reduced compared to when the actuator has multiple storage sections.

[0028] An actuator according to another aspect of the present disclosure includes a housing, a nut accommodated in the housing, a screw shaft that moves relative to the housing along an axis as the nut rotates, a drive unit having a linear encoder that detects the amount of movement of the screw shaft, and a storage unit in which identification information is stored, wherein individual data regarding the specifications of the drive unit is associated with the identification information and stored in a server, and the amount of movement of the screw shaft is corrected based on the individual data.

[0029] This allows the server to store a larger amount of individual data than two-dimensional codes, and therefore the actuator can maintain a relatively high positional accuracy based on a relatively large amount of individual data even when it is replaced. Effect of the Invention

[0030] According to aspects of the present disclosure, the actuator can maintain relatively high positional accuracy even when replaced. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a perspective view of an actuator according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a plan view of the actuator shown in FIG. 1 as viewed from the +Z side. [Diagram 3] FIG. 3 is a side view of the actuator shown in FIG. 1 as viewed from the -X side. [Figure 4] FIG. 4 is a partial cross-sectional view of the first arm along the axis. [Diagram 5] FIG. 5 is a cross-sectional view of the first arm portion taken along line VV shown in FIG. [Figure 6] FIG. 6 is a diagram showing a state in which the second arm unit is inclined with respect to the first arm unit from the reference state of the actuator shown in FIG. [Figure 7] FIG. 7 is a side view of the actuator shown in FIG. 1 as viewed from the +Y side. [Figure 8] FIG. 8 is a diagram showing a state in which the third arm unit is inclined with respect to the second arm unit from the reference state of the actuator shown in FIG. [Figure 9] FIG. 9 is an enlarged plan view of the actuator shown in FIG. [Figure 10] FIG. 10 is a side view of the actuator shown in FIG. 1 as viewed from the -Y side. [Figure 11] FIG. 11 is a diagram showing a state in which the medical instrument has been moved by the third arm unit being driven from the reference state of the actuator shown in FIG. [Figure 12] FIG. 12 is a diagram showing the amount of runout of the screw shaft. [Figure 13] FIG. 13 is a diagram showing a scale positioned at the reference mounting position and the mounting position. [Figure 14] FIG. 14 is a partial cross-sectional view of the first arm along the axis when the screw shaft is in a predetermined position. [Figure 15] FIG. 15 is a diagram illustrating a storage section according to a first modified example of the embodiment of the present disclosure. [Figure 16] FIG. 16 is a block diagram of an actuator and a control device according to a second modification of the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited thereto. The components of each embodiment and each modified example described below can be appropriately combined. In addition, some components may not be used.

[0033] In the following description, the Z direction is the vertical direction, the direction perpendicular to the Z direction is the X direction, and the direction perpendicular to the Z direction and the X direction is the Y direction. The X direction and the Y direction correspond to the horizontal direction. Note that the X, Y, and Z directions are merely examples, and the present disclosure is not limited to these directions.

[0034] 1 is a perspective view of an actuator 1 according to an embodiment of the present disclosure. The actuator 1 is a medical robot arm used by a doctor during surgery. The actuator 1 may also be an industrial robot arm used in the production of industrial products.

[0035] The actuator 1 is detachably attached to, for example, an operating table (not shown), that is, the actuator 1 is replaceable.

[0036] Moreover, the actuator 1 is electrically connected to the control device 100 by wire or wirelessly. A doctor operates the control device 100 to operate the actuator 1.

[0037] The actuator 1 includes a base 10, a first arm unit 20, a first joint portion 30a, a second arm unit 40, a second joint portion 30b, and a third arm unit 50. A medical instrument 2 is fixed to the third arm unit 50 in a replaceable manner.

[0038] The medical instrument 2 is an instrument used for treatment. The medical instrument 2 of this embodiment has a needle-shaped needle portion 2a. A doctor performs treatment by, for example, inserting the needle portion 2a from the tip of the needle portion 2a into an affected area of ​​a patient. Note that FIG. 1 shows the actuator 1 in a reference state H in which the tip of the needle portion 2a faces the -Z side and the needle portion 2a of the medical instrument 2 extends along the Z direction.

[0039] The base 10 is detachably attached to the operating table. The base 10 has a reference surface 11. The reference surface 11 is a surface that comes into contact with a fixed portion (not shown) of the operating table. The reference surface 11 also has a reference point 11a, a first reference axis 11b, a second reference axis 11c, and a third reference axis 11d.

[0040] The reference point 11a is a point included in the reference plane 11, and serves as a reference point for the positions of the components of the actuator 1. For example, when the base 10 has a mounting hole that fits with a fixed portion, the reference point 11a corresponds to the intersection between the central axis of the mounting hole and the reference plane 11. Note that the reference point 11a may be the center of the reference plane 11. The first reference axis 11b, the second reference axis 11c, and the third reference axis 11d are perpendicular to each other at the reference point 11a.

[0041] The actuator 1 is fixed to a fixed portion of the operating table in such a position that the first reference axis 11b is parallel to the X direction, the second reference axis 11c is parallel to the Y direction, and the third reference axis 11d is parallel to the Z direction. Note that the directions of the first reference axis 11b, the second reference axis 11c, and the third reference axis 11d are merely examples, and needless to say, the directions are not limited to these.

[0042] In addition, when the actuator 1 is fixed to a fixed portion of the operating table, viewing the actuator 1 along the Z direction from the +Z side or -Z side is referred to as a "planar view," viewing the actuator 1 along the X direction from the +X side or -X side, and viewing the actuator 1 along the Y direction from the +Y side or -Y side is referred to as a "side view."

[0043] Fig. 2 is a plan view of the actuator 1 shown in Fig. 1 as seen from the +Z side. Fig. 3 is a side view of the actuator 1 shown in Fig. 1 as seen from the -X side. Note that in Fig. 3, a counterweight 23, which will be described later, is omitted from the illustration.

[0044] The first arm unit 20 is fixed to the base 10. The first arm unit 20 includes a first arm 21, a second arm 22, and a counterweight 23. In the reference state H of the actuator 1, the first arm 21 and the second arm 22 are arranged in parallel along the third reference axis 11d in a posture in which they extend along the second reference axis 11c.

[0045] 4 is a partial cross-sectional view of the first arm portion 21 along the axis A1a. The axis A1a is a reference axis in the first arm portion 21. In addition, in the direction along the axis A1a, a first end side of a screw shaft 64a (described later) is defined as a first side S1, and a second end side of the screw shaft 64a is defined as a second side S2.

[0046] The first arm portion 21 includes a drive portion 60a and a guide portion 70a. The axis A1a extends along the second reference axis 11c.

[0047] The driving unit 60a includes a housing 61a, a driving source 62a, a nut 63a, and a screw shaft 64a. The housing 61a has a hollow rectangular parallelepiped shape extending along the axis A1a.

[0048] The driving source 62a is a stepping motor and includes a stator 62aa and a rotor 62ba. The stator 62aa is fixed inside the housing 61a. The rotor 62ba passes through the stator 62aa and is disposed in the housing 61a via a first bearing 65a so as to be rotatable relative to the housing 61a.

[0049] The nut 63a is accommodated in the housing 61a via a second bearing 66a so as to be rotatable relative to the housing 61a. The nut 63a is fixed to the rotor 62ba and rotates integrally with the rotor 62ba. The nut 63a includes a plurality of balls (not shown). The inner circumferential surface of the nut 63a has a spiral groove (not shown) in which the plurality of balls can roll. When the nut 63a rotates, the plurality of balls circulate within the nut 63a.

[0050] The screw shaft 64a is disposed such that a first end is disposed within the housing 61a and a second end is exposed from the housing 61a, with the central axis line aligned with the axis line A1a. The screw shaft 64a passes through the rotor 62ba and the nut 63a. The outer circumferential surface of the screw shaft 64a has a spiral groove (not shown) into which a plurality of balls provided in the nut 63a are fitted so as to be able to roll.

[0051] The threaded shaft 64a is disposed movably relative to the housing 61a. When the actuator 1 is in the reference state H, the position of the threaded shaft 64a corresponds to a first position P1 shown by a solid line in Fig. 4. As described below, the threaded shaft 64a moves along the axis A1a as the nut 63a rotates.

[0052] A stopper member 64ca is disposed at the first end of the screw shaft 64a. When the screw shaft 64a moves in a direction protruding from the housing 61a along the axis A1a, the stopper member 64ca comes into contact with the end face of the first side S1 of the nut 63a. The position where the screw shaft 64a returns a first predetermined distance (e.g., 0.5 mm) along the axis A1a from the position where the stopper member 64ca comes into contact with the end face of the first side S1 of the nut 63a corresponds to a second position P2 indicated by a two-dot chain line in FIG. 4. The distance between the second position P2 and the first position P1 along the axis A1a is set to a second predetermined distance (e.g., 50 mm). A flange member 64da is disposed at the second end of the screw shaft 64a.

[0053] Fig. 5 is a cross-sectional view of the first arm portion 21 taken along line VV shown in Fig. 4. The guide portion 70a guides the screw shaft 64a. As shown in Fig. 4 and Fig. 5, the guide portion 70a includes a support body 71a, a guide member 72a, two guide rails 73aa and 73ba, four linear guides 74aa, 74ba, 74ca, and 74da, and a linear encoder 75a.

[0054] The support 71a is a cylindrical member having a rectangular cross section that extends along the axis A1a and is fixed to the housing 61a. The guide member 72a is an L-shaped member having a cross section and integrally includes a fixed portion 72aa that is fixed to the second end of the screw shaft 64a by a fixing nut 76a, and a rectangular parallelepiped portion 72ba that penetrates the support 71a along the axis A1a.

[0055] As shown in FIG. 5, the two guide rails 73aa, 73ba extend along the axis A1a, and are fixed at positions opposite to each other in the rectangular parallelepiped portion 72ba.

[0056] The four linear guides 74aa, 74ba, 74ca, and 74da are fixed inside the support 71a and guide the two guide rails 73aa and 73ba along the axis A1a. Specifically, the two linear guides 74aa and 74ba are spaced apart from each other in the direction along the axis A1a and guide the guide rail 73aa. The two linear guides 74ca and 74da are spaced apart from each other in the direction along the axis A1a and guide the guide rail 73ba.

[0057] 4 is an optical (for example, reflective) linear encoder. The linear encoder 75a is an incremental linear encoder. The linear encoder 75a includes a scale 75aa and a head 75ba.

[0058] The scale 75aa is attached to a side surface of the rectangular parallelepiped portion 72ba of the guide member 72a and extends along the axis A1a. The scale 75aa has a reference position G and a plurality of slits (not shown) aligned along the direction in which the scale 75aa extends.

[0059] The head 75ba is disposed on the support 71a in a state facing the scale 75aa. The head 75ba includes a light emitting element (e.g., an LED: not shown) and a light receiving element (e.g., a photodiode: not shown). The light emitting element emits light toward the scale 75aa. The light receiving element detects the light reflected by the scale 75aa. The light is not reflected by the slits of the scale 75aa.

[0060] The linear encoder 75a detects the amount of movement of the scale 75aa relative to the head 75ba from the position where the head 75ba detects the reference position G (hereinafter, sometimes referred to as the origin position) based on the detection result of the light receiving element of the head 75ba. The support 71a on which the head 75ba is arranged is fixed to the housing 61a as described above. Also, the guide member 72a to which the scale 75aa is attached moves integrally with the screw shaft 64a along the axis A1a as described later. That is, the scale 75aa moves together with the screw shaft 64a along the axis A1a. Thus, the linear encoder 75a detects the amount of movement of the screw shaft 64a relative to the housing 61a in the direction along the axis A1a. In other words, the linear encoder 75a detects the position of the screw shaft 64a relative to the origin position in the direction along the axis A1a.

[0061] The counterweight 23 is attached to a guide member 72a (see FIG. 2).

[0062] Next, the operation of the first arm 21 will be described. When the rotor 62ba rotates due to the application of a voltage to the driving source 62a, the nut 63a rotates. This causes the screw shaft 64a to move along the axis A1a. Based on the deviation between the target position of the screw shaft 64a and the actual position of the screw shaft 64a detected by the linear encoder 75a, the rotation of the nut 63a is feedback controlled so that the position of the screw shaft 64a becomes the target position. The screw shaft 64a moves between a first position P1 shown in FIG. 4 and a second position P2 shown by a two-dot chain line in FIG. 4. The first position P1 and the second position P2 are determined based on the movable range of the medical instrument 2.

[0063] Furthermore, the guide member 72a moves along the axis A1a integrally with the screw shaft 64a. The guide member 72a is guided by linear guides 74aa, 74ba, 74ca, and 74da via guide rails 73aa and 73ba. Therefore, the screw shaft 64a moves along the axis A1a with higher precision than when the first arm 21 does not include the guide member 72a.

[0064] The second arm 22 has the same configuration as the first arm 21, and the description of the configuration of the second arm 22 will be omitted. However, the reference numerals of the components of the second arm 22 are the same as those of the components of the first arm 21 corresponding to the components of the second arm 22, except that the suffix "a" is changed to "b" instead of "a". Specifically, as shown in Fig. 3, the second arm 22 includes a drive unit 60b and a guide unit 70b corresponding to the drive unit 60a and the guide unit 70a of the first arm 21. In the reference state H of the actuator 1, the axis A1b of the drive unit 60b extends along the second reference axis 11c.

[0065] 1, 2 and 3 connects the first arm unit 20 and the second arm unit 40 so that the second arm unit 40 can be tilted relative to the first arm unit 20. As shown in Figures 2 and 3, the first joint unit 30a includes a first link 31a, a cylindrical first shaft member 32a, a second link 33a, a third link 34a, a cylindrical second shaft member 35a, and a fourth link 36a.

[0066] A first end of the first link 31a is fixed to a guide member 72a of the first arm portion 21. A first shaft member 32a passes through a second end of the first link 31a. In the reference state H of the actuator 1, the first shaft member 32a is disposed such that an axis A2a of the first shaft member 32a is aligned with the first reference axis 11b.

[0067] The second link 33a has a pair of side walls 33aa (see FIG. 2). The pair of side walls 33aa sandwich a second end of the first link 31a. The first shaft member 32a passes through the pair of side walls 33aa. As a result, the second link 33a is inclined around the axis A2a of the first shaft member 32a relative to the first link 31a.

[0068] Further, the second link 33a is connected to a planar first mounting surface 40b of the first mounting portion 40a of the second arm unit 40. The first mounting surface 40b of the second arm unit 40 faces the first arm unit 20. The second link 33a is connected to the first mounting surface 40b so as to be movable along the first mounting surface 40b. Specifically, a linear guide 37a is fixed to the second link 33a, and a guide rail 40c that fits with the linear guide 37a is fixed to the first mounting surface 40b of the second arm unit 40.

[0069] A first end of the third link 34a is fixed to a guide member 72b of the second arm portion 22. A second shaft member 35a passes through a second end of the third link 34a. The second shaft member 35a is disposed such that an axis A3a of the second shaft member 35a and an axis A2a of the first shaft member 32a are parallel to each other.

[0070] The fourth link 36a has a pair of side walls 36aa, similar to the second link 33a. The pair of side walls 36aa sandwich the second end of the third link 34a. The second shaft member 35a penetrates the pair of side walls 36aa. This allows the fourth link 36a to rotate around the axis A3a of the second shaft member 35a relative to the third link 34a. The fourth link 36a is fixed to the first mounting surface 40b of the second arm unit 40.

[0071] In this way, by connecting the first mounting portion 40a of the second arm unit 40 and the first arm unit 20 via the first joint portion 30a, the first arm unit 20, the first joint portion 30a and the first mounting portion 40a form a so-called parallel link mechanism, and the second arm unit 40 tilts and moves relative to the first arm unit 20, as described below.

[0072] Fig. 6 is a diagram showing a state in which the second arm unit 40 is inclined with respect to the first arm unit 20 from the reference state H of the actuator 1 shown in Fig. 3. When the screw shaft 64a of the first arm portion 21 moves from the first position P1 toward the second position P2 from the reference state H of the actuator 1 shown in Fig. 3, as shown in Fig. 6, the second link 33a is inclined about the axis A2a of the first shaft member 32a with respect to the first link 31a, the fourth link 36a is inclined about the axis A3a of the second shaft member 35a with respect to the third link 34a, and the second arm unit 40 is inclined about the first reference axis 11b with respect to the first arm unit 20 in the counterclockwise direction in Fig. 6.

[0073] Furthermore, when the screw shaft 64b of the second arm 22 moves from the first position P1 toward the second position P2 from the reference state H of the actuator 1 shown in FIG. 3, the second link 33a tilts around the axis A2a of the first shaft member 32a relative to the first link 31a, the fourth link 36a tilts around the axis A3a of the second shaft member 35a relative to the third link 34a, and the second arm unit 40 tilts around the first reference axis 11b relative to the first arm unit 20 in the clockwise direction in FIG. 6.

[0074] Furthermore, from the reference state H of the actuator 1 shown in FIG. 3, when the screw shafts 64a, 64b of the first arm portion 21 and the second arm portion 22 move from the first position P1 toward the second position P2 at equal speeds, the second arm unit 40 moves toward the +Y side relative to the first arm unit 20.

[0075] Fig. 7 is a side view of the actuator 1 shown in Fig. 1 when viewed from the +Y side. As shown in Figs. 1, 2 and 7, the second arm unit 40 includes a first attachment portion 40a, a third arm portion 41, and a fourth arm portion .

[0076] As described above, the first attachment portion 40a has the first attachment surface 40b to which the second link 33a and the fourth link 36a of the first joint portion 30a are connected.

[0077] In the reference state H of the actuator 1, the third arm 41 and the fourth arm 42 are disposed in parallel along the third reference axis 11d in a position in which they extend along the first reference axis 11b.

[0078] The third arm 41 and the fourth arm 42 have the same configuration as the first arm 21, and description of the configurations of the third arm 41 and the fourth arm 42 will be omitted. However, the reference numerals of the components of the third arm 41 are the same as those of the components of the first arm 21 that correspond to the components of the third arm 41, except that the suffix of the reference numerals has been changed from "a" to "c."

[0079] Specifically, the third arm 41 includes a drive unit 60c and a guide unit 70c corresponding to the drive unit 60a and the guide unit 70a of the first arm 21. In the reference state H of the actuator 1, an axis A1c of the drive unit 60c extends along the first reference axis 11b. Moreover, the fourth arm 42 includes a drive unit 60d and a guide unit 70d corresponding to the drive unit 60a and the guide unit 70a of the first arm 21. In the reference state H of the actuator 1, an axis A1d of the drive unit 60d extends along the first reference axis 11b.

[0080] 1, 2, and 7 connects the second arm unit 40 and the third arm unit 50 so that the third arm unit 50 can be tilted relative to the second arm unit 40. The second joint unit 30b has the same configuration as the first joint unit 30a, and therefore a description of the second joint unit 30b will be omitted. However, the reference numerals of the components of the second joint unit 30b are the same as those of the components of the first joint unit 30a that correspond to the components of the second joint unit 30b, except that the suffix "a" is changed to "b".

[0081] In the second joint portion 30b, a first end portion of the first link 31b is fixed to a guide member 72c of the third arm portion 41. In the reference state H of the actuator 1, the first shaft member 32b is disposed such that the axis A2b of the first shaft member 32b is aligned with the second reference axis 11c.

[0082] Further, the second link 33b is connected to a planar second mounting surface 50b of a second mounting portion 50a of the third arm unit 50. The second mounting surface 50b of the third arm unit 50 faces the second joint portion 30b. The second link 33b is connected to be movable along the second mounting surface 50b of the third arm unit 50. Specifically, a linear guide 37b is fixed to the second link 33a, and a guide rail 50c that fits with the linear guide 37b is fixed to the second mounting surface 50b of the third arm unit 50.

[0083] Furthermore, a first end of the third link 34b is fixed to a guide member 72d of the fourth arm portion 42. Moreover, the fourth link 36b is fixed to a second mounting surface 50b of the third arm unit 50.

[0084] In this manner, the second mounting portion 50a of the third arm unit 50 and the second arm unit 40 are connected via the second joint portion 30b, so that the second arm unit 40, the second joint portion 30b and the second mounting portion 50a form a so-called parallel link mechanism, and as described below, the third arm unit 50 tilts and moves relative to the second arm unit 40.

[0085] Fig. 8 is a diagram showing a state in which the third arm unit 50 is inclined relative to the second arm unit 40 from the reference state H of the actuator 1 shown in Fig. 7. When the screw shaft 64c of the third arm portion 41 moves from the first position P1 toward the second position P2 from the reference state H of the actuator 1 shown in Fig. 7, as shown in Fig. 8, the second link 33b is inclined about the axis A2b of the first shaft member 32b relative to the first link 31b, the fourth link 36b is inclined about the axis A3b of the second shaft member 35b relative to the third link 34b, and the third arm unit 50 is inclined about the second reference axis 11c relative to the second arm unit 40 in the counterclockwise direction in Fig. 8.

[0086] Furthermore, when the screw shaft 64d of the fourth arm 42 moves from the first position P1 toward the second position P2 from the reference state H of the actuator 1 shown in FIG. 7, the second link 33b tilts around the axis A2b of the first shaft member 32b relative to the first link 31b, the fourth link 36b tilts around the axis A3b of the second shaft member 35b relative to the third link 34b, and the third arm unit 50 tilts around the second reference axis 11c relative to the second arm unit 40, in the clockwise direction in FIG. 8.

[0087] Furthermore, from the reference state H of the actuator 1 shown in FIG. 7, when the screw shafts 64c, 64d of the third arm portion 41 and the fourth arm portion 42 move from the first position P1 toward the second position P2 at equal speeds, the third arm unit 50 moves toward the +X side relative to the second arm unit 40.

[0088] Fig. 9 is an enlarged plan view of the actuator 1 shown in Fig. 2. Fig. 10 is a side view of the actuator 1 shown in Fig. 1 when viewed from the -Y side. As shown in Figs. 7, 9, and 10, the third arm unit 50 includes a drive unit 60e and an instrument guide unit 80.

[0089] The driving section 60e of the third arm unit 50 has the same configuration as the driving section 60e of the first arm unit 20 described above, and a description of the configuration of the driving section 60e of the third arm unit 50 will be omitted. However, the reference numerals of the components of the driving section 60e of the third arm unit 50 are those of the components of the driving section 60a of the first arm unit 20 that correspond to the components of the driving section 60e of the third arm unit 50, with the suffix "a" changed to "e". In the reference state H of the actuator 1, the axis A1e of the driving section 60e extends along the third reference axis 11d.

[0090] The instrument guide portion 80 guides the medical instrument 2. The instrument guide portion 80 includes a second attachment portion 50a and a guide member 81.

[0091] A housing 61e of the drive unit 60e is fixed to the second attachment portion 50a (see FIG. 9). The second attachment portion 50a has a second attachment surface 50b to which the second joint portion 30b is connected, and a guide surface 50d. As described above, the second link 33b and the fourth link 36b of the second joint portion 30b are connected to the second attachment surface 50b.

[0092] The guide surface 50d is a plane parallel to the second mounting surface 50b. A guide member 81 is attached to the guide surface 50d so as to be movable relative to the second mounting portion 50a. Specifically, a pair of linear guides 81a is fixed to the guide member 81, and a guide rail 50e that fits with the pair of linear guides 81a is fixed to the guide surface 50d. The guide rail 50e extends along the axis A1e of the drive unit 60e. Therefore, the guide member 81 moves relative to the second mounting portion 50a along the axis A1e of the drive unit 60e.

[0093] 10, the guide member 81 is fixed to a second end of a screw shaft 64e provided in the driving unit 60e. In addition, the medical instrument 2 is fixed to the guide member 81. In other words, when the screw shaft 64e moves along the axis line A1e, the guide member 81 and the medical instrument 2 move together along the axis line A1e relative to the second attachment portion 50a.

[0094] The instrument guide unit 80 further includes a linear encoder 82. The linear encoder 82 is an optical (e.g., reflective) linear encoder. The linear encoder 82 is an incremental linear encoder. The linear encoder 82 includes a scale 82a and a head 82b (see FIGS. 9, 10, and 11).

[0095] The scale 82a is attached to the second attachment portion 50a and extends along the axis A1e. The scale 82a has a reference position G (see FIG. 11) and a plurality of slits (not shown) aligned along the direction in which the scale 82a extends.

[0096] The head 82b is disposed on the guide member 81 in a state facing the scale 82a. The head 82b includes a light-emitting element (e.g., an LED: not shown) and a light-receiving element (e.g., a photodiode: not shown). The light-emitting element emits light toward the scale 82a. The light-receiving element detects the light reflected by the scale 82a. The light is not reflected by the slits in the scale 82a.

[0097] The linear encoder 82 detects the amount of movement of the head 82b relative to the scale 82a based on the detection result of the light receiving element of the head 82b. The housing 61e is fixed to the second mounting portion 50a to which the scale 82a is attached. The guide member 81 on which the head 82b is disposed moves integrally with the screw shaft 64e. That is, the head 82b moves together with the screw shaft 64e. Thus, the linear encoder 82 detects the amount of movement of the screw shaft 64e relative to the housing 61e. Specifically, the linear encoder 82 detects the position of the screw shaft 64e relative to the reference position G in the direction along the axis A1e.

[0098] Fig. 11 is a diagram showing a state in which the medical instrument 2 has been moved by driving the third arm unit 50 from the reference state H of the actuator 1 shown in Fig. 10. When the screw shaft 64e of the drive unit 60e moves from the first position P1 toward the second position P2 from the reference state H of the actuator 1 shown in Fig. 10, the medical instrument 2 moves along the axis line A1e to the -Z side as shown in Fig. 11. On the other hand, when the screw shaft 64e of the drive unit 60e moves from the second position P2 toward the first position P1 from the state of the actuator 1 shown in Fig. 11, the medical instrument 2 moves along the axis line A1e to the +Z side.

[0099] With the actuator 1 configured as described above fixed to a fixed portion of the operating table, a doctor inputs an operation amount to the control device 100. The control device 100 adjusts the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e corresponding to the input operation amount based on the detection results of each of the linear encoders 75a, 75b, 75c, 75d, and 82. As described above, each of the screw shafts 64a, 64b, 64c, 64d, and 64e is guided by the guide members 72a, 72b, 72c, 72d, and 81, and moves precisely along the axes A1a, A1b, A1c, A1d, and A1e.

[0100] This allows for precise adjustment of the attitude and position of the second arm unit 40 and the third arm unit 50 relative to the first arm unit 20. Furthermore, the attitude and position of the medical instrument 2 is precisely adjusted, and the medical instrument 2 moves precisely.

[0101] Such an actuator 1 may be replaced for reasons such as maintenance. Before and after replacement of the actuator 1, the actuator 1 is attached to the operating table so that the reference point 11a, the first reference axis 11b, the second reference axis 11c, and the third reference axis 11d are aligned.

[0102] However, when the actuator 1 is replaced, even if the amount of operation by the doctor is the same, the position of the medical instrument 2 after the movement may be different before and after the replacement of the actuator 1. This is because the distance between the reference point 11a and the medical instrument 2 and the attitude of the medical instrument 2 with respect to the first reference axis 11b, the second reference axis 11c, and the third reference axis 11d are different due to individual differences in the actuator 1. The individual differences in the actuator 1 are caused by dimensional variations in the components of the actuator 1 and errors in the mounting positions of the components. In other words, when the actuator 1 is replaced, the position of the components of the actuator 1 with respect to the reference point 11a may be shifted, which may reduce the positional accuracy of the medical instrument 2.

[0103] 1, the actuator 1 further includes a storage unit 90. The storage unit 90 is fixed to the base 10. The storage unit 90 stores individual data related to the specifications of the actuator 1. Specifically, the storage unit 90 has an image 90a of a two-dimensional code into which the individual data is converted. In this embodiment, the storage unit 90 is a sticker on which the image 90a is printed, and is attached to the base 10.

[0104] The individual data is information on the specifications of the driving units 60a, 60b, 60c, 60d, and 60e. Specifically, the individual data is numerical data on the following items (1), (2), (3), (4), (5), (6), (7), and (8). The individual data is actually measured from the manufacture of the actuator 1 to its shipment.

[0105] Item (1): Runout amount of each screw shaft 64a, 64b, 64c, 64d, 64e Item (2): The angles of the axes A1a, A1b of the first arm 21 and the second arm 22 with respect to the first reference axis 11b in the reference state H of the actuator 1 Item (3): Angles of the axes A1c, A1d of the third arm 41 and the fourth arm 42 with respect to the second reference axis 11c in the reference state H of the actuator 1 Item (4): Angle of axis A1e of drive unit 60e with respect to third reference axis 11d in reference state H of actuator 1 Item (5): Angle of axis A2a, A3a of the first joint portion 30a with respect to the first reference axis 11b in the reference state H of the actuator 1 Item (6): Angle of axis A2b, A3b of second joint portion 30b with respect to second reference axis 11c in reference state H of actuator 1 Item (7): Distance of the mounting position of each scale 75aa, 75ab, 75ac, 75ad, 82a from the reference mounting position in the direction along the axis A1a, A1b, A1c, A1d, A1e Item (8): A first inclination angle of the direction in which each of the scales 75aa, 75ab, 75ac, 75ad, and 82a extends relative to the direction along the axis lines A1a, A1b, A1c, A1d, and A1e.

[0106] 12 is a diagram showing a deflection amount D1 of the screw shaft 64a. The deflection amount D1 of the screw shaft 64a is the distance between a tip point 64ba of the screw shaft 64a and the axis A1a. The tip point 64ba of the screw shaft 64a is the intersection point of the end face on the second end side of the screw shaft 64a and the central axis CL of the screw shaft 64a. The deflection amount D1 of the screw shaft 64a indicates the amount of deviation in position between the tip point 64ba of the screw shaft 64a and the axis A1a.

[0107] The deflection amount D1 of the screw shaft 64a is correlated with the amount of movement of the screw shaft 64a from the first position P1. For example, the deflection amount D1 of the screw shaft 64a increases as the screw shaft 64a moves from the first position P1 toward the second position P2.

[0108] The same is true for the runout amount D1 of the screw shafts 64b, 64c, 64d, and 64e. That is, the runout amount D1 of the screw shaft 64b is the distance between a tip point 64bb (see Figs. 3 and 6) of the screw shaft 64b and the axis A1b. The runout amount D1 of the screw shaft 64c is the distance between a tip point 64bc (see Figs. 7 and 8) of the screw shaft 64c and the axis A1c. The runout amount D1 of the screw shafts 64d and 64e is the distance between a tip point 64bd (see Figs. 7 and 8) of the screw shaft 64d and the axis A1d. The runout amount D1 of the screw shaft 64e is the distance between a tip point 64be (see Figs. 10 and 11) of the screw shaft 64e and the axis A1e.

[0109] In other words, the run-out amount D1 of each screw shaft 64a, 64b, 64c, 64d, 64e in item (1) indicates the amount of positional deviation between the end points 64ba, 64bb, 64bc, 64bd, 64be of the screw shafts 64b, 64c, 64d, 64e and the axes A1a, A1b, A1c, A1d, A1e corresponding to the end points 64ba, 64bb, 64bc, 64bd, 64be.

[0110] Item (2) indicates the amount of deviation of the inclination of the axes A1a, A1b of the first arm 21 and the second arm 22 relative to the first reference axis 11b in the reference state H of the actuator 1. Item (3) indicates the amount of deviation of the inclination of the axes A1c, A1d of the third arm 41 and the fourth arm 42 relative to the second reference axis 11c in the reference state H of the actuator 1. Item (4) indicates the amount of deviation of the inclination of the axis A1e of the drive part 60e relative to the third reference axis 11d in the reference state H of the actuator 1.

[0111] Item (5) indicates the amount of deviation of the inclination of the axes A2a, A3a of the first joint portion 30a relative to the first reference axis 11b in the reference state H of the actuator 1. Item (6) indicates the amount of deviation of the inclination of the axes A2b, A3b of the second joint portion 30b relative to the second reference axis 11c in the reference state H of the actuator 1.

[0112] Fig. 13 is a diagram showing the scale 75aa positioned at the reference mounting position P3 and the mounting position P4. In Fig. 13, the scale 75aa positioned at the reference mounting position P3 is shown by a dashed line, and the scale 75aa positioned at the mounting position P4 is shown by a solid line.

[0113] The reference mounting position P3 is a mounting position that serves as a reference for the scale 75aa. The scale 75aa located at the reference mounting position P3 extends along the axis A1a. Since the scale 75aa is attached to the guide member 72a, the mounting position P4 of the scale 75aa has a positional variation in the direction along the axis A1a with respect to the reference mounting position P3. The distance D2 is the distance between the scale 75aa located at the reference mounting position P3 and the scale 75aa located at the mounting position P4 in the direction along the axis A1a, and indicates the amount of deviation of the mounting position P4 from the reference mounting position P3 in the direction along the axis A1a.

[0114] Specifically, the distance D2 is the amount of deviation of the reference position G of the scale 75aa at the mounting position P4 from the reference position G of the scale 75aa at the reference mounting position P3 in the direction along the axis A1a. The amount of deviation of the reference position G corresponds to the amount of deviation of the position of the screw shaft 64a. The same applies to each of the linear encoders 75b, 75c, 75d, and 82.

[0115] In other words, the distance D2 of the mounting position P4 of each scale 75aa, 75ab, 75ac, 75ad, 82a relative to the reference mounting position P3 in the direction along the axes A1a, A1b, A1c, A1d, A1e in item (7) indicates the amount of deviation of each screw shaft 64a, 64b, 64c, 64d, 64e in the direction along the axes A1a, A1b, A1c, A1d, A1e.

[0116] In addition, by attaching the scale 75aa to the guide member 72a, the direction in which the scale 75aa located at the attachment position P4 extends has an inclination variation with respect to the direction in which the scale 75aa located at the reference attachment position P3 extends (i.e., the direction along the axis A1a). The first inclination angle θ1 is the inclination angle of the direction in which the scale 75aa located at the attachment position P4 extends with respect to the direction along the axis A1a. The larger the first inclination angle θ1, the smaller the amount of movement of the screw shaft 64a detected by the linear encoder 75a becomes. In other words, the first inclination angle θ1 corresponds to an error in the amount of movement of the screw shaft 64a. The same applies to each of the linear encoders 75b, 75c, 75d, and 82.

[0117] That is, the first inclination angle θ1 of the direction in which each of the scales 75aa, 75ab, 75ac, 75ad, 82a extends relative to the direction along the axes A1a, A1b, A1c, A1d, A1e in item (8) corresponds to the error in the amount of movement of the screw shaft 64a.

[0118] If the difference in the values ​​of the above items (1), (2), (3), (4), (5), (6), (7), and (8) between the actuator 1 before and after replacement is relatively large, the difference in the position of the medical instrument 2 after movement before and after replacement of the actuator 1 will be relatively large, even if the amount of operation by the doctor is the same.

[0119] For example, with regard to item (4), if the angle of the axis A1e of the drive unit 60e relative to the third reference axis 11d in the reference state H of the actuator 1 differs between the actuator 1 before and after replacement, the direction of movement of the medical instrument 2 differs, and therefore the position of the medical instrument 2 after movement differs.

[0120] Regarding item (7), if the mounting positions P4 of each scale 75aa, 75ab, 75ac, 75ad, and 82a are different between the actuator 1 before and after replacement, the positions of each screw shaft 64a, 64b, 64c, 64d, and 64e will be different, and the position of the medical instrument 2 will be different.

[0121] Therefore, the control device 100 acquires the individual data stored in the storage unit 90, and corrects the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e corresponding to the operation amount input by the doctor. Specifically, the control device 100 is provided with a camera (not shown), and acquires the individual data by capturing an image 90a with the camera.

[0122] Then, the control device 100 corrects the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e to the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e corresponding to the case where the runout amount D1 of each of the screw shafts 64a, 64b, 64c, 64d, and 64e in item (1) is zero. As a result, the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e is corrected to the movement amount when the tip points 64ba, 64bb, 64bc, 64bd, and 64be move along the axes A1a, A1b, A1c, A1d, and A1e.

[0123] Furthermore, the control device 100 corrects the movement amount of each of the screw shafts 64a, 64b to the movement amount of each of the screw shafts 64a, 64b corresponding to the case where the axis lines A1a, A1b of the first arm section 21 and the second arm section 22 are aligned along the first reference axis line 11b (i.e., the angle of item (2) is zero) in the reference state H of the actuator 1. As a result, the movement amount of each of the screw shafts 64a, 64b is corrected to the movement amount when each of the screw shafts 64a, 64b moves along the first reference axis line 11b.

[0124] Furthermore, the control device 100 corrects the movement amount of each of the screw shafts 64c, 64d to the movement amount of each of the screw shafts 64c, 64d corresponding to the case where the axes A1c, A1d of the third arm portion 41 and the fourth arm portion 42 are aligned along the second reference axis 11c (i.e., the angle of item (3) is zero) in the reference state H of the actuator 1. As a result, the movement amount of each of the screw shafts 64c, 64d in the reference state H of the actuator 1 is corrected to the movement amount when each of the screw shafts 64a, 64b moves along the second reference axis 11c.

[0125] Then, the control device 100 corrects the movement amount of the screw shaft 64e to the movement amount of the screw shaft 64e corresponding to the case where the axis A1e of the drive unit 60e is along the third reference axis 11d (i.e., the angle of item (4) is zero) in the reference state H of the actuator 1. As a result, the movement amount of each screw shaft 64e in the reference state H of the actuator 1 is corrected to the movement amount when the screw shaft 64e moves along the third reference axis 11d.

[0126] Furthermore, the control device 100 corrects the rotation direction of the second arm unit 40 relative to the first arm unit 20 to a rotation direction of the second arm unit 40 relative to the first arm unit 20 that corresponds to the case where the axes A2a, A3a of the first joint portion 30a are aligned along the first reference axis 11b (i.e., the angle of item (5) is zero) in the reference state H of the actuator 1. As a result, the rotation direction of the second arm unit 40 relative to the first arm unit 20 in the reference state H of the actuator 1 is corrected to a rotation direction around the first reference axis 11b.

[0127] Then, the control device 100 corrects the rotation direction of the third arm unit 50 relative to the second arm unit 40 to a rotation direction of the third arm unit 50 relative to the second arm unit 40 that corresponds to the case where the axes A2b, A3b of the second joint portion 30b are aligned along the second reference axis 11c (i.e., the angle of item (6) is zero) in the reference state H of the actuator 1. As a result, the rotation direction of the third arm unit 50 relative to the second arm unit 40 in the reference state H of the actuator 1 is corrected to a rotation direction around the second reference axis 11c.

[0128] The control device 100 also corrects the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e to the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e corresponding to the case where the mounting position P4 of each of the scales 75aa, 75ab, 75ac, 75ad, and 82a is located at the reference mounting position P3 (that is, the distance D2 of item (7) and the first tilt angle θ1 of item (8) are both zero). As a result, the positions of the screw shafts 64a, 64b, 64c, 64d, and 64e are corrected to the positions when the mounting position P4 of each of the scales 75aa, 75ab, 75ac, 75ad, and 82a is located at the reference mounting position P3.

[0129] As a result, the medical instrument 2 moves and tilts from the reference state H of the actuator 1 with reference to the reference point 11a, the first reference axis 11b, the second reference axis 11c, and the third reference axis 11d. In other words, it is possible to suppress the positional deviation of the medical instrument 2 before and after replacement of the actuator 1. Therefore, even when the actuator 1 is replaced, a relatively high positional accuracy can be maintained.

[0130] As described above, according to this embodiment, the actuator 1 includes a housing 61a, a nut 63a accommodated in the housing 61a, a screw shaft 64a that moves relative to the housing 61a along the axis A1a as the nut 63a rotates, a drive unit 60a having a linear encoder 75a that detects the amount of movement of the screw shaft 64a, and a storage unit 90 in which individual data regarding the specifications of the drive unit 60a is stored.

[0131] This allows the amount of movement of the screw shaft 64a to be corrected based on the individual data, and therefore the actuator 1 can maintain a relatively high positional accuracy even when it is replaced.

[0132] Moreover, the linear encoder 75a is an incremental type linear encoder.

[0133] This makes it possible to reduce the cost of the linear encoder 75a.

[0134] Furthermore, the individual data of the actuator 1 includes a distance D2 of the attachment position P4 of the scale 75aa of the linear encoder 75a relative to a reference attachment position P3 in the direction along the axis A1a.

[0135] The distance D2 affects the position of the screw shaft 64a. Therefore, by correcting the amount of movement of the screw shaft 64a based on the distance D2, the actuator 1 can reliably maintain a relatively high positional accuracy even when it is replaced.

[0136] The individual data also includes a first tilt angle θ1 of the direction in which the scale 75aa of the linear encoder 75a extends relative to the direction along the axis A1a.

[0137] The first tilt angle θ1 affects the position of the screw shaft 64a. Therefore, by correcting the movement amount of the screw shaft 64a based on the first tilt angle θ1, the actuator 1 can reliably maintain a relatively high positional accuracy even when it is replaced.

[0138] The storage unit 90 also has an image 90a of a two-dimensional code into which the individual data has been converted.

[0139] This allows the storage section 90 to be easily attached to the actuator 1. Furthermore, the storage section 90 can be made smaller in size.

[0140] The actuator 1 also includes five drive units 60a, 60b, 60c, 60d, and 60e and one storage unit 90. The one storage unit 90 stores individual data relating to the specifications of each of the five drive units 60a, 60b, 60c, 60d, and 60e.

[0141] This allows for lower costs compared to when the actuator 1 includes a plurality of storage sections 90.

[0142] Next, an actuator 1 according to a modified example of the embodiment of the present disclosure will be described.

[0143] For example, the individual data may further include the numerical data of the following items (9), (10), (11), (12), (13), (14), (15), (16), and (17).

[0144] Item (9): Angle of the central axis CL of each of the screw shafts 64a, 64b with respect to the first reference axis 11b in the reference state H of the actuator 1 Item (10): Angle of the central axis CL of each of the screw shafts 64c, 64d with respect to the second reference axis 11c in the reference state H of the actuator 1 Item (11): Angle of the central axis CL of the screw shaft 64e with respect to the third reference axis 11d in the reference state H of the actuator 1 Item (12): Angle of axis A1b of second arm 22 with respect to axis A1a of first arm 21 in reference state H of actuator 1 Item (13): Angles of axes A1c, A1d of the third arm 41 and the fourth arm 42 with respect to the axis A1a of the first arm 21 in the reference state H of the actuator 1 Item (14): Angle of axis A1e of drive portion 60e with respect to axis A1a of first arm portion 21 in reference state H of actuator 1 Item (15): Angle of axis A2a, A3a of the first joint portion 30a with respect to axis A1a of the first arm portion 21 in the reference state H of the actuator 1 Item (16): Angle of axis A2b, A3b of second joint portion 30b with respect to axis A1a of first arm portion 21 in reference state H of actuator 1 Item (17): Lead error of each screw shaft 64a, 64b, 64c, 64d, and 64e

[0145] Items (9), (10), and (11) correspond to the deflection amount D1 of each of the screw shafts 64a, 64b, 64c, 64d, and 64e in item (1).

[0146] Item (12) corresponds to the angle of the axis A1b of the second arm 22 relative to the first reference axis 11b in item (2). Item (13) corresponds to the angle of the axes A1c, A1d of the third arm 41 and the fourth arm 42 relative to the second reference axis 11c in item (3). Item (14) corresponds to the angle of the axis A1e of the drive unit 60e relative to the third reference axis 11d in item (4). Item (15) corresponds to the angle of the axes A2a, A3a of the first joint portion 30a relative to the first reference axis 11b in item (5). Item (16) corresponds to the angle of the axes A2b, A3b of the second joint portion 30b relative to the second reference axis 11c in item (6).

[0147] Item (17) is the difference between the lead of each of the screw shafts 64a, 64b, 64c, 64d, and 64e and the design value (so-called dimensional error). The control device 100 corrects the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e to the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e corresponding to the case where the lead error of each of the screw shafts 64a, 64b, 64c, 64d, and 64e is zero. As a result, the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e is corrected to the movement amount when the lead of each of the screw shafts 64a, 64b, 64c, 64d, and 64e is equal to the design value. In addition, the lead error of each screw shaft 64a, 64b, 64c, 64d, and 64e in item (17) may be stored as an error in the amount of movement when each screw shaft 64a, 64b, 64c, 64d, and 64e is moved from the first position P1 to the second position P2.

[0148] In addition, when the individual data includes items (9), (10), (11), (12), (13), (14), (15), and (16), it does not have to include the angle of the axis A1b of the second arm 22 with respect to the first reference axis 11b in the reference state H of the actuator 1 in item (1), and items (2), (3), (4), (5), and (6).

[0149] 14 is a partial cross-sectional view of the first arm portion 21 along the axis A1a when the screw shaft 64a is in a predetermined position. The predetermined position of the screw shaft 64a is a position where the stopper member 64ca abuts on the end face of the first side S1 of the nut 63a.

[0150] The individual data may further include the numerical data of the following items (18), (19), (20), (21), (22), and (23). Note that in this modification, for the sake of simplicity, the first arm 21 will be described with respect to items (18), (19), (20), (21), (22), and (23), but the same applies to the corresponding parts of the second arm 22, the third arm 41, the fourth arm 42, and the drive unit 60e.

[0151] Item (18): Distance L1 between a first portion of the screw shaft 64a (specifically, an end face of the first side S1 of the flange member 64da: corresponding to a predetermined portion of the screw shaft 64a) and a second portion of the nut 63a (specifically, an end face of the second side S2 of the nut 63a: corresponding to a predetermined portion of the nut 63a) in a direction along the axis A1a when the screw shaft 64a is in a predetermined position shown in FIG. Item (19): Distance L2 between a third portion of the guide member 72a (specifically, an end face of the first side S1 of the fixing portion 72aa: corresponding to a predetermined portion of the guide member 72a) and a fourth portion of the housing 61a (specifically, an end face of the second side S2 of the housing 61a: corresponding to a predetermined portion of the housing 61a) in a direction along the axis A1a when the screw shaft 64a is in a predetermined position Item (20): A distance L3 between a fifth portion of the screw shaft 64a (specifically, an end face of the first side S1 of the stopper member 64ca) and a sixth portion of the rotor 62ba (specifically, an end face of the first side S1 of the rotor 62ba) in a direction along the axis A1a when the screw shaft 64a is in a predetermined position Item (21): Distance L4 between the seventh portion of the fixing nut 76a (specifically, the end face of the first side S1 of the fixing nut 76a) and the second portion of the nut 63a (i.e., the end face of the second side S2 of the nut 63a) in the direction along the axis A1a when the screw shaft 64a is in a predetermined position Item (22): Distance L5 between the third portion of the guide member 72a (i.e., the end face of the first side S1 of the fixing portion 72aa) and the eighth portion of the support body 71a (specifically, the end face of the second side S2 of the support body 71a) in the direction along the axis A1a when the screw shaft 64a is in a predetermined position Item (23): Distance L6 between a ninth portion of the guide member 72a (specifically, the end surface of the first side S1 of the rectangular parallelepiped portion 72ba) and a tenth portion of the support body 71a (specifically, the end surface of the first side S1 of the support body 71a) in a direction along the axis A1a when the screw shaft 64a is in a predetermined position

[0152] If the distances L1, L2, L3, L4, L5, and L6 of the above items (18), (19), (20), (21), (22), and (23) differ between the actuator 1 before and after replacement, the position after the movement of the screw shaft 64a will differ before and after replacement of the actuator 1, even though the amount of operation by the doctor is the same, and therefore the position after the movement of the medical instrument 2 will differ. The distances L1, L2, L3, L4, L5, and L6 vary from actuator 1 to actuator 1 due to differences from the design values ​​of the dimensions of components such as the nut 63a and the screw shaft 64a.

[0153] Therefore, the control device 100 corrects the movement amount of the screw shaft 64a to the movement amount of the screw shaft 64a corresponding to the values ​​of the distances L1, L2, L3, L4, L5, and L6 when the dimensions of the components of the first arm portion 21, such as the nut 63a and the screw shaft 64a, are equal to the design values. In other words, the movement amount of the screw shaft 64a is corrected to the movement amount when the dimensions of the components of the first arm portion 21 are equal to the design values.

[0154] As described above, according to this modified example, the individual data includes the distance L1 between a first portion of the screw shaft 64a and a second portion of the nut 63a in a direction along the axis A1a when the screw shaft 64a is in a predetermined position.

[0155] The actuator 1 further includes a guide member 72a that guides the threaded shaft 64a along the axis A1a. The individual data includes a distance L2 between a third portion of the guide member 72a and a fourth portion of the housing 61a in a direction along the axis A1a when the threaded shaft 64a is in a predetermined position.

[0156] The distances L1 and L2 affect the position of the screw shaft 64a. Therefore, by correcting the movement amount of the screw shaft 64a based on the distances L1 and L2, the actuator 1 can reliably maintain a relatively high positional accuracy even when it is replaced. The same applies to the distances L3, L4, L5, and L6.

[0157] The predetermined position of the screw shaft 64a may be the first position P1 or the second position P2 shown in FIG. 4. The first portion may be a portion of the screw shaft 64a other than the end face of the first side S1 of the flange member 64da. The second portion may be a portion of the nut 63a other than the end face of the second side S2 of the nut 63a. The third portion may be a portion of the guide member 72a other than the end face of the first side S1 of the fixing portion 72aa. The fourth portion may be a portion of the housing 61a other than the end face of the second side S2 of the housing 61a. The fifth portion may be a portion of the screw shaft 64a other than the end face of the first side S1 of the stopper member 64ca. The sixth portion may be a portion of the rotor 62ba other than the end face of the first side S1 of the rotor 62ba. The seventh portion may be a portion of the fixing nut 76a other than the end face of the first side S1 of the fixing nut 76a. The eighth portion may be a portion of the support 71a other than the end face of the first side S1 of the support 71a. The ninth portion may be a portion of the guide member 72a other than the end face of the first side S1 of the rectangular parallelepiped portion 72ba. The tenth portion may be a portion of the support 71a other than the end face of the first side S1 of the support 71a.

[0158] The individual data may further include the numerical data of the following items (24), (25), and (26). Note that in this modification, for the sake of simplicity, the first arm 21 will be described with respect to items (24), (25), and (26), but the same applies to the corresponding parts of the second arm 22, the third arm 41, the fourth arm 42, and the drive unit 60e.

[0159] Item (24): A distance L7 between a tenth portion of the guide member 72a (specifically, an end face of the second side S2 of the fixing portion 72aa: corresponding to the second predetermined portion of the guide member 72a) and a fourth portion of the housing 61a (specifically, an end face of the second side S2 of the housing 61a: corresponding to the second predetermined portion of the housing 61a) in a direction along the axis A1a when the screw shaft 64a is in a predetermined position shown in FIG. 14, and a distance L8 between the head 75ba and the reference position G.

[0160] Item (25): Distance L7 between the tenth portion of the guide member 72a and the fourth portion of the housing 61a in the direction along the axis A1a when the head 75ba detects the reference position G

[0161] Item (26): A second inclination angle θ2 of the central axis CL of the screw shaft 64a relative to the axis A1a (see FIG. 12)

[0162] In item (24), the end face of the second side S2 of the fixed portion 72aa corresponding to the tenth portion of the guide member 72a is a portion where the first link 31a of the first arm unit 20 is disposed. Specifically, the distance L8 is the distance between the detection position R of the portion (i.e., the light receiving element) where the head 75ba detects the reference position G and the reference position G in the direction along the axis A1a when the screw shaft 64a is in the predetermined position shown in FIG.

[0163] In item (25), the time when head 75ba detects reference position G is when distance L8 is zero. In other words, item (25) means distance L7 when distance L8 is zero.

[0164] If the distances L7, L8 and the second tilt angle θ2 of the above items (24), (25), and (26) are different between the actuator 1 before and after replacement, even though the amount of operation by the doctor is the same, the position after the movement of the screw shaft 64a will be different before and after replacement of the actuator 1, and therefore the position after the movement of the medical instrument 2 will be different. The distances L7, L8 and the second tilt angle θ2 vary from actuator 1 to actuator 1 due to differences from the design values ​​of the dimensions of components such as the nut 63a and the screw shaft 64a.

[0165] Regarding items (24) and (25), the control device 100 corrects the distance L8 so that the distance L7 is equal to the design value of the dimensions of the components of the first arm portion 21. Furthermore, the control device 100 corrects the movement amount of the screw shaft 64a to the movement amount of the screw shaft 64a that corresponds to the corrected distance L8. As a result, the movement amount of the screw shaft 64a is corrected to the movement amount when the dimensions of the components of the first arm portion 21 are equal to the design value.

[0166] Regarding item (26), the control device 100 corrects the movement amount of the screw shaft 64a to the movement amount of the screw shaft 64a corresponding to the case where the central axis CL of the screw shaft 64a is along the axis A1a (i.e., the second inclination angle θ2 is zero). As a result, the movement amount of the screw shaft 64a is corrected to the movement amount when the screw shaft 64a moves along the axis A1a.

[0167] As described above, according to this modification, the guide member 72a that guides the screw shaft 64a along the axis A1a is further provided. The linear encoder 75a includes a scale 75aa having a reference position G, and a head 75ba that detects the reference position G. The individual data includes a distance L7 between a second predetermined portion of the guide member 72a and a second predetermined portion of the housing 61a, and a distance L8 between the head 75ba and the reference position G, in a direction along the axis A1a when the screw shaft 64a is at a predetermined position.

[0168] The individual data also includes a distance L7 between a second predetermined portion of the guide member 72a and a second predetermined portion of the housing 61a in the direction along the axis A1a when the head 75ba detects the reference position G.

[0169] The individual data also includes a second inclination angle θ2 of the central axis CL of the screw shaft 64a with respect to the axis A1a.

[0170] The distances L7, L8 and the second tilt angle θ2 affect the position of the screw shaft 64a. Therefore, by correcting the movement amount of the screw shaft 64a based on the distances L7, L8 and the second tilt angle θ2, the actuator 1 can reliably maintain a relatively high positional accuracy even when it is replaced.

[0171] The storage unit 90 may have an image of a one-dimensional code into which the individual data is converted. Furthermore, the storage unit 90 may be attached to a portion other than the base 10 that does not restrict the operation of the actuator 1.

[0172] Hereinafter, an actuator 1 according to a modification of the embodiment of the present disclosure will be described, focusing mainly on the differences from the actuator 1 according to the above embodiment.

[0173] FIG. 15 is a diagram showing a storage unit 190 according to a first modified example of the embodiment of the present disclosure. The storage unit 190 of the first modified example is a so-called beacon. The storage unit 190 has a housing 191, a memory unit 192, and a transmitter 193. The housing 191 accommodates the memory unit 192 and the transmitter 193. The memory unit 192 stores individual data. The transmitter 193 outputs a signal including the individual data stored in the memory unit 192 to the outside. The control device 100 acquires the individual data by receiving the signal output by the storage unit 190. The memory unit 192 of the storage unit 190 can store a larger amount of individual data than the two-dimensional code constituting the image 90a.

[0174] FIG. 16 is a block diagram of an actuator 1 and a control device 100 according to a second modified example of the embodiment of the present disclosure.

[0175] In the present second modified example, the storage unit 290 of the actuator 1 stores identification information ID for identifying the actuator 1. The identification information ID is, for example, an identification number. The storage unit 290 has an image 290a of a two-dimensional code into which the identification information ID is converted.

[0176] In the second modified example, the individual data DATA is not stored in the storage unit 290, but is stored in the server 300 on the network 200 in association with the identification information ID. Specifically, the server 300 stores a table T in which the identification information ID and the individual data DATA are associated with each other. The individual data DATA may include, in addition to the numerical data of each of the above items, numerical data indicating the lead error for each predetermined movement amount (for example, 1 mm) for each of the screw shafts 64a, 64b, 64c, 64d, and 64e. The numerical data of the lead error has a relatively large amount of information. The numerical data of the lead error can correct the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e with even higher accuracy.

[0177] The control device 100 is connected to a network 200 by wire or wirelessly, and is connected to a server 300 via the network 200. The server 300 is capable of storing a larger amount of information than a two-dimensional code.

[0178] The control device 100 acquires the identification information ID stored in the storage unit 290 by capturing the image 290a with the camera as described above. Furthermore, the control device 100 acquires the individual data DATA corresponding to the acquired identification information ID from the server 300.

[0179] The control device 100 corrects the movement amount of each of the screw shafts 64a, 64b, 64c, 64d, and 64e corresponding to the operation amount input by the doctor based on the acquired individual data DATA, in the same manner as in the above embodiment.

[0180] According to the second modified example, the actuator 1 includes a housing 61a, a nut 63a accommodated in the housing 61a, a screw shaft 64a that moves relative to the housing 61a along an axis A1a as the nut 63a rotates, a drive unit 60a having a linear encoder 75a that detects the amount of movement of the screw shaft 64a, and a storage unit 290 in which identification information ID is stored. Individual data DATA relating to the specifications of the drive unit 60a is stored in the server 300 in association with the identification information ID. The amount of movement of the screw shaft 64a is corrected based on the individual data DATA.

[0181] The server 300 can store a larger amount of individual data DATA than two-dimensional codes, and therefore the actuator 1 can maintain a relatively high positional accuracy based on a relatively large amount of individual data DATA even when it is replaced.

[0182] The identification information ID may be information for identifying the actuators 60a, 60b, 60c, 60d, and 60e. In this case, a plurality of (five) different identification information IDs for identifying the actuators 60a, 60b, 60c, 60d, and 60e are stored in the storage unit 290. Even in this case, the individual data DATA is stored in the server 300 in the same manner as in the case where the identification information ID is information for identifying the actuator 1.

[0183] Also, the first arm unit 20 may not include the second arm portion 22. In this case, the first joint portion 30a does not include the third link 34a, the second shaft member 35a, and the fourth link 36a, but includes the first link 31a, the first shaft member 32a, the second link 33a, and a motor (not shown) that tilts the second link 33a around the first shaft member 32a relative to the first link 31a. Also, the second link 33a is fixed to the first mounting surface 40b.

[0184] Similarly, the second arm unit 40 may not include the fourth arm portion 42. In this case, the second joint portion 30b does not include the third link 34b, the second shaft member 35b, and the fourth link 36b, but includes the first link 31b, the first shaft member 32b, the second link 33b, and a motor (not shown) that tilts the second link 33b around the first shaft member 32b relative to the first link 31b. In addition, the second link 33b is fixed to the second mounting surface 50b.

[0185] Moreover, the actuator 1 does not have to include the first arm unit 20 and the first joint unit 30a. In this case, the actuator 1 has three drive units 60c, 60d, and 60e, and the second arm unit 40 is attached to the base unit 10. Furthermore, the actuator 1 does not have to include the second arm unit 40 and the second joint unit 30b. In this case, the actuator 1 has one drive unit 60e, and the third arm unit 50 is attached to the base unit 10.

[0186] The linear encoders 75a and 82 may be magnetic linear encoders, or may be absolute linear encoders.

[0187] The control device 100 and the server 300 are computers, and include, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an internal storage unit, an input interface, and an output interface. The CPU, ROM, RAM, and internal storage unit are connected by an internal bus. Programs such as BIOS are stored in the ROM. The internal storage unit is, for example, a HDD (Hard disk drive) or a flash memory, and stores an operating system program and application programs. The CPU realizes various functions by executing programs stored in the ROM or the internal storage unit while using the RAM as a work area. [Explanation of symbols]

[0188] 1 Actuator 11a Reference point 11b 1st reference axis (reference axis) 11c 2nd reference axis (reference axis) 11d 3rd reference axis (reference axis) 20 First Arm Unit 30a First joint 30b Second joint 40 Second Arm Unit 50 3rd Arm Unit 60a Drive unit 61a Housing 63a Nut 64a Screw shaft 64ba tip 72a Guide member 75a Linear Encoder 75aa scale 75ba head 90 Storage area 100 Control device 300 Servers A1a axis CL Central axis of the screw shaft D2 Distance along the axis between the scale located at the reference mounting position and the scale located at the mounting position G Reference position P3 Reference mounting position P4 Mounting position θ1 1st inclination angle θ2 2nd inclination angle

Claims

1. A housing, a nut accommodated in the housing, a screw shaft that moves relative to the housing along an axis as the nut rotates, and a drive unit having a linear encoder that detects the amount of movement of the screw shaft; A storage unit in which individual data regarding the specifications of the drive unit is stored. Actuator.

2. The linear encoder is an incremental linear encoder. The actuator of claim 1 .

3. The individual data includes a distance of a mounting position of a scale of the linear encoder relative to a reference mounting position in a direction along the axis. The actuator of claim 1 .

4. the individual data includes a first tilt angle of a direction in which a scale of the linear encoder extends with respect to a direction along the axis; The actuator of claim 1 .

5. The individual data includes a distance between a predetermined portion of the screw shaft and a predetermined portion of the nut in a direction along the axis when the screw shaft is in a predetermined position, The actuator of claim 1 .

6. Further provided is a guide member that guides the screw shaft along the axis, The individual data includes a distance between a predetermined portion of the guide member and a predetermined portion of the housing in a direction along the axis when the screw shaft is in a predetermined position. The actuator of claim 1 .

7. Further provided is a guide member that guides the screw shaft along the axis, the linear encoder includes a scale having a reference position and a head for detecting the reference position; The individual data includes a distance between a second predetermined portion of the guide member and a second predetermined portion of the housing in a direction along the axis when the screw shaft is in a predetermined position, and a distance between the head and the reference position. The actuator of claim 1 .

8. The individual data includes a second inclination angle of the central axis of the screw shaft relative to the axis, The actuator of claim 1 .

9. The storage unit has an image of a two-dimensional code into which the individual data is converted. The actuator of claim 1 .

10. Further provided is a guide member that guides the screw shaft along the axis, the linear encoder includes a scale having a reference position and a head for detecting the reference position; the individual data includes a distance between a second predetermined portion of the guide member and a second predetermined portion of the housing in a direction along the axis when the head detects the reference position; The actuator of claim 1 .

11. The drive unit includes five of the drive units and one of the storage units, The storage unit stores individual data regarding the specifications of each of the five drive units. The actuator of claim 1 .

12. A housing, a nut accommodated in the housing, a screw shaft that moves relative to the housing along an axis as the nut rotates, and a drive unit having a linear encoder that detects the amount of movement of the screw shaft; A storage unit in which identification information is stored, The individual data regarding the specifications of the drive unit is stored in a server in association with the identification information; The movement amount of the screw shaft is corrected based on the individual data. Actuator.

Images