JP2012034883A - Remote controlled actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a remote-controlled actuator that changes the position of a tool attached to the end of an elongated pipe with high dimensional accuracy via its remote controlled operation.SOLUTION: The actuator includes an elongated spindle guide 3, an end part 2 attached to the tip of the same while the attached end part 2 easily changes its position, and a tool 1 rotatably provided at the end part 2. The spindle guide 3 includes a rotation shaft 22 to transmit rotation to the spindle 13, and a guide hole 30a opened throughout both the ends of the same. A positional change drive source 42 moves forward and backward a positional operation member 31 inserted, with its position being variable, through the guide hole 30a to change the position of the end part 2. When a positional control means 53 to control the position of the positional change drive source 42 takes control of the positional operation member 31 over its movement from the standard operation start position to the target position, the process includes a step where the position operation member is temporarily moved away from the target position.

Description

  The present invention relates to a remotely operated actuator that can change the posture of a tool by remote operation and is used for medical use, machining, and the like.

  There are remote-operated actuators that are used for bone processing for medical purposes and drilling and cutting for mechanical processing. The remote operation type actuator remotely controls a tool provided at the end of a long and narrow pipe portion having a linear shape or a curved shape. However, since the conventional remote control type actuator only controls the rotation of the tool by remote control, it has been difficult to process complicated shapes and parts that are difficult to see from the outside. Further, in drilling, it is required that not only a straight line but also a curved shape can be processed. Furthermore, in the cutting process, it is required that a deep part inside the groove can be processed. Hereinafter, taking the medical use as an example, the prior art and problems of the remote control actuator will be described.

  In the field of orthopedics, there is an artificial joint replacement operation in which a joint that has become worn out due to bone aging or the like is replaced with a new artificial one. In this operation, it is necessary to process the patient's living bone so that the artificial joint can be inserted. In order to increase the adhesive strength between the living bone and the artificial joint after the operation, the shape of the artificial joint is required. It is required to process with high accuracy.

  For example, in hip joint replacement surgery, an artificial joint insertion hole is formed in the medullary cavity at the center of the femur bone. In order to maintain the contact strength between the artificial joint and the bone, it is necessary to increase the contact area between them, and the hole for inserting the artificial joint is processed into an elongated shape extending to the back of the bone. As a medical actuator used for such a bone cutting process, a tool is rotatably provided at the distal end of an elongated pipe portion, and by driving a rotational drive source such as a motor provided on the proximal end side of the pipe portion, There exists a thing of the structure which rotates a tool via the rotating shaft arrange | positioned inside (for example, patent document 1). In this type of medical actuator, the rotating part exposed to the outside is only the tool at the tip, so that the tool can be inserted deep into the bone.

  Artificial joint replacement surgery involves skin incision and muscle cutting. That is, the human body must be damaged. In order to minimize the scratches, the pipe part may not be straight but may be appropriately curved. In order to cope with such a situation, there are the following conventional techniques. For example, in Patent Document 2, an intermediate portion of a pipe portion is bent twice, and the axial center position on the distal end side and the axial center position on the proximal end side of the pipe portion are shifted. There are other known cases where the axial position of the pipe portion is shifted between the tip end side and the axial center side. In Patent Document 3, the pipe portion is rotated 180 degrees.

JP 2007-301149 A U.S. Pat. No. 4,466,429 US Pat. No. 4,265,231 JP 2001-17446 A

  If there is a wide gap between the living bone and the artificial joint with the artificial joint inserted in the artificial bone insertion hole of the living bone, the adhesion time after the operation becomes longer, so the gap is as narrow as possible. desirable. It is also important that the contact surface between the living bone and the artificial joint is smooth, and high accuracy is required for processing the hole for inserting the artificial joint. However, no matter what the shape of the pipe part, the operating range of the tool is limited by the shape of the pipe part. It is difficult to process the artificial joint insertion hole so that the gap is narrow and the contact surface of both is smooth.

  Generally, bones of patients undergoing artificial joint replacement surgery are often weakened due to aging or the like, and the bones themselves may be deformed. Therefore, it is more difficult to process the artificial joint insertion hole than is normally conceivable.

  Therefore, the present applicant tried to make it possible to remotely change the posture of the tool provided at the tip for the purpose of relatively easily and accurately processing the hole for inserting the artificial joint. . This is because, if the posture of the tool can be changed, the tool can be held in an appropriate posture regardless of the shape of the pipe portion. However, as a result of testing with a prototype, the direction of the frictional resistance generated in the operating member changes depending on the operating direction of the operating member for remote operation, or the operating member is elastically deformed due to the frictional resistance, so that the operating member is repeated. It has been found that an error may occur in the operation amount of the operating member when operating.

  In addition, some remote operation type actuators that do not have an elongated pipe portion can change the posture of the portion where the tool is provided with respect to the portion gripped by the hand (for example, Patent Document 4). No changes have been proposed.

  It is an object of the present invention to change the posture of a tool provided at the tip of an elongated pipe portion with high accuracy by remote operation, especially when the operation member for remote operation is repeatedly operated, the difference in the direction of frictional resistance. It is an object of the present invention to provide a remote control type actuator that can reduce an error caused by.

  A remote operation type actuator according to the present invention includes an elongated spindle guide part, a tip member attached to the tip of the spindle guide part via a tip member connecting part so that the posture can be freely changed, and the tip member being rotatable. A tool rotation drive source for rotating the tool; and a posture change drive source for operating the posture of the tip member. The tip member rotatably supports a spindle that holds the tool. The spindle guide portion has a rotation shaft for transmitting the rotation of the tool rotation drive source to the spindle and guide holes penetrating both ends, and the tip is in contact with the tip member and moves forward and backward. Thus, a flexible posture operation member that changes the posture of the tip member is inserted into the guide hole so as to freely advance and retract, and the posture operation member is advanced and retracted by the posture change drive source. Make. An attitude control means for controlling the attitude change drive source is provided, and the attitude control means follows a predetermined rule when performing control to move the attitude operation member from a reference position that is an operation start position to a target position. It includes a step of temporarily moving the posture operation member to the side away from the target position. The reference position is an operation start position, that is, a current position immediately before the operation start, and is not limited to a specific position such as an origin position.

  According to this configuration, the rotation of the tool rotation drive source is transmitted to the spindle of the tip member via the rotation shaft, and the tool held on the spindle rotates, thereby cutting the bone or the like. The posture of the tip member at this time is determined by the position of the tip of the posture operation member. When the posture operation member is moved back and forth by the posture change drive source, the position of the tip of the posture operation member changes, and the tip member changes its posture. The posture changing drive source is provided at a position away from the tip member, and the posture change of the tip member is performed by remote control. Since the posture operation member is inserted into the guide hole, the posture operation member does not shift in the direction intersecting the longitudinal direction, and can always act properly on the tip member, and the posture change operation of the tip member Is done accurately. In addition, since the posture operation member is flexible, the posture changing operation is reliably performed even when the spindle guide portion is curved.

  The posture operation member is inserted through guide holes penetrating both ends of the elongated spindle guide portion, and is thin and long and has low rigidity. Therefore, the length in the forward / backward direction changes under the influence of external force. That is, the posture operation member can be regarded as a spring system. The direction of the friction generated between the posture operation member and the inner peripheral surface of the guide hole is different depending on the movement of the posture operation member, that is, the movement toward the side where the acting force on the tip member increases and the movement toward the decrease side. Also, when moving the posture operation member to the side where the acting force on the tip member increases, the friction at the contact portion between the posture operation member and the tip member is large, but when moving to the side where the force acts decreases, Friction at the contact portion between the operating member and the tip member hardly occurs. For these reasons, when the posture of the tip member is changed, even if the driving force applied to the posture control member by the posture change drive source is constant, the length of the posture control member is different if the posture control member moves forward and backward. Changes, and the position of the tip of the posture operation member is not constant. This affects the accuracy of the tip member posture change control. When the attitude control means performs control to move the attitude operation member from the reference position to the target position, if the attitude operation member is temporarily moved beyond the target position and then moved back to the target position, the attitude A factor that changes the length of the operation member can be eliminated. Thereby, the posture change control of the tip member can always be performed with a certain accuracy.

In this invention, the posture operation member includes a rigid distal force transmission member disposed on the distal member side, a rigid proximal force transmission member disposed on the posture change drive source side, and these distal force transmission members. It may consist of a flexible and long intermediate force transmission member that transmits force between the member and the proximal force transmission member.
By making the distal force transmission member and the proximal force transmission member rigid, the acting force of the posture operation member can be reliably transmitted to the distal member, and the driving force of the posture change drive source can be reliably transmitted to the posture operation member. Can be communicated to. Moreover, the posture control member as a whole can be made flexible by making the intermediate force transmission member flexible and long.

In this invention, when the posture control member moves the posture operation member from the reference position to the target position on the side where the acting force on the tip member is reduced, the posture control member moves the target position beyond the target position and then returns to the target position. As described above, it is preferable to control the posture changing drive source.
Comparing the case where the posture operation member is moved to the side where the acting force on the tip member is increased and the case where the posture operation member is moved to the side where the force is reduced is compared with the case where the posture operation member is moved to the side where the force is reduced. The amount of movement of the tip of the posture operation member is large. That is, there is a difference in the amount of movement of the tip of the posture operation member between the case where the acting force is increased and the case where the acting force is decreased. When moving the attitude control member from the reference position to the target position on the side where the acting force on the tip member is reduced, if the position is moved beyond the target position and then returned to the target position, the above difference in movement amount is eliminated. Thus, when the driving force applied to the posture operation member is constant, the amount of movement of the tip of the posture operation member can be made constant. Thereby, the accuracy of the posture change control of the tip member is improved.

In this invention, the tip member changes its posture along the cylindrical or spherical guide surface of the tip member connecting portion, and the guide hole and the posture operation member inserted into the guide hole are Provided at a plurality of locations around the center of curvature of the guide surface, the posture changing drive source is provided individually for each posture operation member, and the tip by the balance of the acting force of the plurality of posture operation members on the tip member It is good also as what changes and maintains the attitude | position of a member.
With this configuration, since the acting force is applied to the tip member by the plurality of posture operation members and the posture of the tip member is changed and maintained, the posture stability of the tip member can be improved. Thus, when changing the attitude | position of a front-end | tip member with a some attitude | position operation member, the said attitude | position control means can be comprised as follows.

In other words, the posture control means is configured to move the posture operation members so that the posture operation members move in the same direction and complete the operation when moving the plurality of posture operation members from the reference position to the target positions. It is good to control.
If each posture operation member moves in the same direction and completes the operation, the frictional relationship with other members becomes the same in each posture operation member. Can be almost the same.

Further, when the plurality of posture operation members are moved from the reference position to the respective target positions, the posture control means moves each posture operation member to a position beyond the target position and then returns to the target position. Further, the posture changing drive source may be controlled.
By appropriately setting the position beyond the target position, the amount of movement of the tip of each posture operation member at the time when the operation is completed can be made substantially the same for a plurality of posture operation members that move in different directions.

Further, the posture control means may control the posture changing drive source so as to drive each posture operation member in synchronization.
If each posture operation member is driven synchronously, the posture change of the tip member can be smoothly performed in a short time.

The attitude control means may be configured by combining the ideas of the attitude control means.
For example, when the posture control means according to the first method moves the plurality of posture operation members from the reference position to the respective target positions, the posture control means moves to the side where the acting force on the tip member increases in the first step. The posture operation member is moved to a position before the target position, and the posture operation member for moving the posture operation member to the side where the acting force on the tip member decreases is moved to a position beyond the target position. The posture-changing drive source is controlled so that the posture control member that moves to the side where the acting force on the force increases and the posture control member that decreases are moved to their target positions.

  In addition, when the plurality of posture operation members are moved from the reference position to their respective target positions, the posture control means according to the second method moves the force acting on the tip member to the side that increases in the first step. The posture operation member is moved to a target position, and the posture operation member is moved to a position beyond the target position, and the action force on the tip member is moved in a second process. The posture changing drive source is controlled so that the posture control member to be moved to the decreasing side is moved to the target position.

  Further, the posture control means according to the third method moves the plurality of posture operation members to the side where the acting force on the tip member increases in the first step when moving the plurality of posture operation members from the reference position to the respective target positions. In the second step, the posture operation member is moved to a position before the target position, and the posture operation member is moved to a position where the acting force on the tip member is reduced. And a posture control member that moves the posture operation member that moves to the side where the acting force against the tip member increases to a target position and moves the posture control member to the side where the force against the tip member decreases decreases before the target position. The posture control member is moved to the second front position closer to the target position than the first front position and moved to the side where the acting force on the tip member decreases in the third process. Until controls the attitude altering drive source to move.

  In addition, when the plurality of posture operation members are moved from the reference position to the respective target positions, the posture control means according to the fourth method moves the force acting on the tip member to the side in which it increases in the first step. The posture operation member is moved to a position beyond the target position, and the posture operation member for moving the posture operation member to the side where the acting force on the tip member decreases is moved to a position beyond the target position. The posture changing drive source is controlled so that the posture operation member that moves to the side where the acting force on the head increases and the posture control member that moves to the side where the force acts on the posture are moved to their target positions.

  A remote control type actuator according to the present invention is provided with an elongated spindle guide portion, a tip member attached to the tip of the spindle guide portion via a tip member connecting portion so that the posture can be freely changed, and rotatably provided on the tip member. A tool rotation drive source for rotating the tool, and a posture change drive source for manipulating the posture of the tip member. The tip member rotatably supports a spindle holding the tool. The spindle guide portion has a rotation shaft for transmitting the rotation of the tool rotation drive source to the spindle and guide holes penetrating at both ends, and the tip is in contact with the tip member and moves forward and backward. Then, a flexible posture operation member that changes the posture of the tip member is inserted into the guide hole so as to freely advance and retract, and the posture operation member is moved forward and backward by the posture change drive source. And a posture control means for controlling the posture change drive source. The posture control means is defined when performing control to move the posture operation member from a reference position, which is an operation start position, to a target position. In accordance with established rules, it includes a process of temporarily moving the posture operation member away from the target position, so that the posture of the tool provided at the tip of the elongated pipe portion can be accurately changed by remote operation, When the posture operation member for remote operation is repeatedly operated, an error caused by a difference in the direction of frictional resistance can be reduced.

It is a figure which shows the whole structure of the remote control type actuator concerning embodiment of this invention. (A) is a cross-sectional view of the tip member and spindle guide portion of the remote operation type actuator, (B) is a IIB-IIB cross-sectional view thereof, (C) is a diagram showing a connection structure between the tip member and the rotating shaft, (D ) Is a view of the housing of the tip member as seen from the base end side. It is sectional drawing of the front-end | tip member and spindle guide part which show a state different from FIG. 2 (A). It is IV-IV sectional drawing of FIG. It is the figure which represented typically two states from which an attitude | position operation member differs. (A), (B), (C) is a figure which shows the change of the position of the attitude | position operation member in the attitude | position change of the front-end | tip member by the 1st method of attitude | position change control in steps. It is a time chart which shows the change of the base end position of each posture operation member at the time of posture change of the tip member by the 1st method of posture change control. It is a time chart which shows the change of the amount of displacement of the tip member at the time of posture change of the tip member by the 1st method of posture change control. (A), (B), (C) is a figure which shows the change of the position of the attitude | position operation member in the attitude | position change of the front-end | tip member by the 2nd method of attitude | position change control in steps. It is a time chart which shows the change of the base end position of each posture operation member at the time of posture change of the tip member by the 2nd method of posture change control. It is a time chart which shows the change of the amount of displacement of a tip member at the time of posture change of the tip member by the 2nd method of posture change control. (A), (B), (C), (D) is a figure which shows the change of the position of the attitude | position operation member in the attitude | position change of the front-end | tip member by the 3rd method of attitude | position change control in steps. It is a time chart which shows the change of the base end position of each posture operation member at the time of posture change of the tip member by the 3rd method of posture change control. It is a time chart which shows the change of the amount of displacement of the tip member at the time of posture change of the tip member by the 3rd method of posture change control. (A), (B), (C) is a figure which shows the change of the position of the attitude | position operating member in the attitude | position change of the front-end | tip member by the 4th method of attitude | position change control in steps. It is a time chart which shows the change of the base end position of each posture operation member at the time of posture change of the tip member by the 4th method of posture change control. It is a time chart which shows change of the amount of displacement of a tip member at the time of posture change of a tip member by the 4th method of posture change control.

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the remote control type actuator includes a tip member 2 for holding a rotary tool 1, an elongated spindle guide portion 3 having the tip member 2 attached to the tip so that the posture can be freely changed, and the spindle guide. A drive unit housing 4a to which the base end of the unit 3 is coupled, and a controller 5 for controlling the tool rotation drive mechanism 4b and the attitude change drive mechanism 4c in the drive unit housing 4a are provided. The drive unit housing 4a constitutes the drive unit 4 together with the built-in tool rotation drive mechanism 4b and posture changing drive mechanism 4c.

  As shown in FIGS. 2 and 3, the tip member 2 has a spindle 13 rotatably supported inside a substantially cylindrical housing 11 by a pair of bearings 12. The spindle 13 has a cylindrical shape with an open end, and the shank 1a of the tool 1 is non-rotatably fitted to a spline portion 13a having an inner diameter. The retaining pin 14 prevents the shank 1a from coming off. The tip member 2 is attached to the tip of the spindle guide portion 3 via the tip member connecting portion 15. The tip member connecting portion 15 is a means for supporting the tip member 2 so that the posture thereof can be freely changed, and includes a spherical bearing.

  Specifically, the distal end member connecting portion 15 includes a guided portion 11 a that is a reduced inner diameter portion of the proximal end of the housing 11 and a hook-shaped portion of a retaining member 21 that is fixed to the distal end of the spindle guide portion 3. It is comprised with the guide part 21a. The guide surfaces F1 and F2 that are in contact with each other 11a and 21a are spherical surfaces having a center of curvature O located on the center line CL1 of the spindle 13 and having a smaller diameter toward the proximal end side. As a result, the tip member 2 is prevented from being detached from the spindle guide portion 3 and is supported so as to be freely changeable in posture. 2 shows a state where the center line CL1 of the spindle 13 and the center line CL2 of the spindle guide 3 are the same line, and FIG. 3 shows a state where the center lines CL1 and CL2 intersect each other and have an angle θ. .

  The spindle guide portion 3 has a rotating shaft 22 that transmits the rotational force of the tool rotation drive source 41 (FIG. 1) in the drive portion housing 4 a to the spindle 13. In this example, the rotating shaft 22 is a wire and can be elastically deformed to some extent. As the material of the wire, for example, metal, resin, glass fiber or the like is used. The wire may be a single wire or a stranded wire.

  As shown in FIG. 2C, the spindle 13 and the rotary shaft 22 are connected to each other via a joint 23 such as a universal joint so as to be able to transmit rotation. The joint 23 includes a groove 13 a provided at the closed base end of the spindle 13 and a protrusion 22 a provided at the distal end of the rotating shaft 22 and engaged with the groove 13 a. The center of the connecting portion between the groove 13a and the protrusion 22a is the center of curvature O of the guide surfaces F1 and F2 and the moving position. You may comprise the rotating shaft 22 and the processus | protrusion 22a with another member.

  The spindle guide section 3 has an outer pipe 25 that is an outer shell of the spindle guide section 3, and the rotation shaft 22 is located at the center of the outer pipe 25. The rotating shaft 22 is rotatably supported by a plurality of rolling bearings 26 that are arranged apart from each other in the axial direction. The rolling bearing 26 is a rotation support member that rotatably supports the rotation shaft 22 in the spindle guide 3. Between each rolling bearing 26, spring elements 27A and 27B for generating a preload on the rolling bearing 26 are provided. The spring elements 27A and 27B are, for example, compression coil springs. There are an inner ring spring element 27A for generating a preload on the inner ring of the rolling bearing 26 and an outer ring spring element 27B for generating a preload on the outer ring, which are arranged alternately. The retaining member 21 is fixed to the pipe end portion 25a of the outer pipe 25 by a fixing pin 28, and rotatably supports the distal end portion of the rotary shaft 22 via a rolling bearing 29 at the distal end inner peripheral portion thereof. The pipe end portion 25a may be a separate member from the outer pipe 25 and may be joined by welding or the like.

  Between the inner diameter surface of the outer pipe 25 and the rotating shaft 22, three guide pipes 30 penetrating at both ends are provided at circumferential positions at a phase of 120 degrees. And the attitude | position operation member 31 (31U, 31L, 31R) is penetrated by the guide hole 30a which is an internal diameter hole of each guide pipe 30 so that advancing and retreating is possible. In this example, the posture operation member 31 is made of a flexible and long intermediate force transmission member 31a made of a wire, and a distal force transmission member 31b and a proximal force transmission member 31c made of columnar rigid bodies respectively disposed at both ends thereof. It consists of.

  The distal end of the distal force transmission member 31 b is spherical, and the spherical distal end is in contact with the bottom surface of the radial groove 11 b formed on the proximal end surface 11 of the housing 11. The groove 11b and the tip force transmission member 31b constitute an anti-rotation mechanism 37, and the tip of the tip force transmission member 31b inserted into the groove 11b hits the side surface of the groove 11b, so that the tip member 2 is against the spindle guide portion 3. This prevents the spindle 13 from rotating about the center line CL1. The proximal end of the proximal force transmission member 31c is also spherical, and the spherical proximal end is in contact with the side surface of the lever 43b described later.

  In addition to the guide pipe 30, a plurality of reinforcing shafts 34 are arranged on the same pitch circle C as the guide pipe 30 between the inner diameter surface of the outer pipe 25 and the rotary shaft 22. These reinforcing shafts 34 are for ensuring the rigidity of the spindle guide portion 3. The intervals between the guide pipe 30 and the reinforcing shaft 34 are equal. The guide pipe 30 and the reinforcing shaft 34 are in contact with the inner diameter surface of the outer pipe 25 and the outer diameter surface of the rolling bearing 26. Thereby, the outer diameter surface of the rolling bearing 26 is supported.

  As shown in FIGS. 1 and 4, the tool rotation drive mechanism 4 b includes a tool rotation drive source 41. The tool rotation drive source 41 is, for example, an electric motor, and its output shaft 41 a is coupled to the proximal end of the rotation shaft 22. The attitude control drive mechanism 4c includes three attitude control drive sources 42 (42U, 42L, 42R) respectively corresponding to the attitude changing members 31 (31U, 31L, 31R) (FIG. 2B). Prepare. The attitude control drive source 42 is, for example, an electric linear actuator, and converts the rotary motion of a built-in rotary motor (not shown) into a linear motion via a rotation / linear motion conversion mechanism 45 that also serves as a reverse input prevention mechanism. Converted and transmitted to the output rod 42a. The output rod 42a moves in the left-right direction in FIG. 1, and the movement amount of the output rod 42a, that is, the movement amount of the attitude control drive source 42 is detected by the movement amount detector 46.

As the rotation / linear motion conversion mechanism 45, a sliding screw type feed screw mechanism such as a triangular screw or a trapezoidal screw can be adopted. By providing such a sliding screw type feed screw mechanism, the posture control drive source 42 has a reverse input preventing function for preventing the posture control driving source 31 from operating with the force from the posture operation member 31. As the rotation / linear motion conversion mechanism 45, a ball screw, a rack / pinion mechanism, or the like may be used in addition to the sliding screw type. In that case, it is desirable to provide a reverse input prevention mechanism separately. In this case, a worm gear or the like can be employed as the reverse input prevention mechanism. In addition, a reduction mechanism with a large reduction ratio can be employed.
Note that the reverse input prevention mechanism is not necessarily provided in the posture control drive source 42, and may be provided anywhere in the posture control drive mechanism 4 c, that is, between the posture control drive source 42 and the posture operation member 31. Good.

  The linear motion of the output rod 42 a is transmitted to the posture operation member 31 via the force increase transmission mechanism 43. The boost transmission mechanism 43 has a lever 43b that is rotatable around a support shaft 43a. The force of the output rod 42a acts on an action point P1 of the lever 43b that is long from the support shaft 43a. The force is applied to the posture operation member 31 at the force point P <b> 2 having a short distance, and the output of the posture control drive source 42 is increased and transmitted to the posture operation member 31. A thin strain-generating portion 43ba is provided at an intermediate portion of the lever 43b, and strain sensors 47 for detecting strain generated in the strain-generating portion 43ba are attached to both sides of the strain-generating portion 43ba. The rotary shaft 22 passes through an opening 44 formed in the lever 43b.

  The controller 5 includes a control device 5A composed of a computer and a program executed thereon, and manually operated rotational speed setting means 50 and posture setting means 51 that are input to the computer. The rotation speed setting means 50 sets the rotation speed of the spindle 13. The posture setting means 51 sets a target posture of the tip member 2 with respect to the spindle guide portion 3. The controller 5A in the controller 5 includes a tool rotation control means 52 for controlling the tool rotation drive source 41, a posture control means 53 for controlling each posture control drive source 42, and a tip by the computer and the program. An external force estimating means 54 for estimating an external force acting on the member 2 is configured.

  The tool rotation control means 52 outputs to the motor driver 55 according to the input from the rotation speed setting means 50 and drives the tool rotation drive source 41.

  The posture control means 53 includes an initial posture holding control unit 53a and a posture change control unit 53b. The initial posture holding control unit 53a and the posture change control unit 53b output the motor driver 56 in response to an input from the posture setting means 51 and drive the posture control drive source 42.

  The initial posture holding control unit 53 a controls each posture control drive source 42 so as to give each posture operating member 31 an initial posture holding force that enables the tip member 2 to be held in a predetermined initial posture. The initial posture is, for example, a posture in which the center line CL1 of the spindle 13 and the center line CL2 of the spindle guide portion 3 are the same line. The posture of the tip member 2 is determined by the balance between the external force acting on the tip member 2 and the thrust of each posture control drive source 42. Therefore, the tip member 2 is held in the initial posture by controlling each posture control drive source 42 so as to apply the initial posture holding force to the posture operation member 31. The posture of the tip member 2 is maintained, that is, the rigidity of the tip member 2 is secured by the thrust of the posture control drive source 42.

The posture change control unit 53b controls each posture control drive source 42 so that the posture operation members 31 advance and retreat in cooperation with each other to change the posture of the tip member 2.
For example, when the upper one posture operation member 31U in FIG. 2 is advanced to the distal end side and the other two posture operation members 31L and 31R are moved backward, the upper posture operation member 31U causes the housing 11 of the tip member 2 to move. By being pushed, the tip member 2 changes its posture along the guide surfaces F1 and F2 to the side in which the tip side faces downward in FIG. When each posture operation member 31 is moved back and forth, the housing 11 of the tip member 2 is pushed by the left and right posture operation members 31L and 31R, so that the tip member 2 moves to the side where the tip side is upward in FIG. The posture is changed along the guide surfaces F1 and F2.

  Further, when the left posture operation member 31L is advanced to the distal end side and the right posture operation member 31R is moved backward while the upper posture operation member 31U is stationary, the distal end member 2 is moved by the left posture operation member 31L. When the housing 11 is pushed, the tip member 2 changes its posture along the guide surfaces F1 and F2 to the right, that is, the side facing the back side of the paper surface in FIG. When the left and right posture operation members 31L and 31R are moved back and forth, the housing 11 of the tip member 2 is pushed by the right posture operation member 31R, so that the tip member 2 moves along the guide surfaces F1 and F2 toward the left side. Change the posture.

  In the posture change control of the tip member 2, the posture of the tip member 2 is set to the amount of advancement / retraction of the posture operation member 31 with respect to the origin position with the position of the posture operation member 31 when the tip member 2 is in the initial posture as the origin position. Will be decided accordingly. Specifically, the posture change control unit 53b converts the target posture of the tip member 2 set by the posture setting means 51 into the advance / retreat amount of the posture operation member 31 corresponding thereto, and the posture is changed according to the converted advance / retreat amount. The operation amount of the control drive source 42 is changed. As described above, if the operation amount of the attitude control drive source 42 is changed in accordance with the advance / retreat amount of the attitude operation member 31, the attitude change control of the tip member 2 is simplified and easy.

  By the way, since the intermediate force transmission member 31a of the posture operation member 31 is thin and long and flexible, the intermediate force transmission member 31a expands and contracts in the forward / backward direction by an external force. That is, the posture operation member 31 can be regarded as a spring system as shown in FIG. In the figure, the intermediate force transmission member 31a is represented by a rigid body 31aa and a pair of springs 31ab and 31ac. Part A of FIG. 5 shows a state where the posture operation member 31 is stationary after moving to the base end side (right side). 5 shows a state where the posture operation member 31 is stationary after moving to the distal end side (left side). The magnitudes of the driving forces for driving the posture operation member 31 are the same. In the figure, f1 is a friction force generated between the tip force transmission member 31b and the inner peripheral surface of the guide hole 30a, f2 is a friction force generated between the intermediate force transmission member 31a and the inner peripheral surface of the guide hole 30a, and f3. Is a frictional force generated between the proximal force transmission member 31c and the inner peripheral surface of the guide hole 30a, and K is a spring constant of the springs 31ab and 31ac.

  Even when the magnitude of the driving force for driving the posture operation member 31 is the same, as shown in the figure, the posture operation member 31 moves to the proximal end side than the distal end side moves. The amount of movement of the tip of the operation member 31 increases. This is because the directions of the frictional forces f1, f2, and f3 change depending on the direction in which the posture operation member 31 advances and retreats. The difference ΔL in the movement amount is expressed by ΔL = {2 (f2 + 2 · f1)} / K. Is done.

  Further, when the posture operation member 31 moves to the proximal end side, since the acting force on the distal end member 2 decreases, there is almost no friction at the contact portion between the posture operation member 31 and the distal end member 2, but the posture operation member 31. When the head moves to the tip side, the acting force on the tip member 2 increases, so that the friction at the contact portion between the posture operation member 31 and the tip member 2 is large. This also causes a difference ΔL in the amount of movement of the tip of the posture operation member 31.

  The posture of the tip member 2 is determined by the relative position of the tip of each posture operation member 31. As described above, if there is a difference ΔL in the amount of movement of the tip of the posture operation member 31 depending on the state of advancement / retraction of the posture operation member 31, the accuracy of the posture change control of the tip member 2 is affected. Therefore, in the posture change control unit 53b, as described later, when the posture operation member 31 is moved from the reference position to the target position for changing the posture of the tip member 2, the posture is temporarily changed according to the predetermined rule R. The operation member 31 is moved away from the target position. The reference position is the operation start position, that is, the current position immediately before the operation start, and is not necessarily the origin position. As a result, a factor causing a difference in the amount of movement of the tip of the posture operation member 31 is eliminated, and posture change control of the tip member 2 can always be performed with constant accuracy. There are several methods for this attitude change control. In each method described below, the tip member 2 is bent upward about the X axis (FIG. 2B) to change from the initial posture state of FIG. 2A to the state of FIG. . The predetermined rule R is controlled by any of the following methods.

A first method of attitude change control will be described with reference to FIGS.
FIG. 6A shows a state before the bending operation. At this time, the posture of the distal end member 2 is the initial posture, and the base ends of the posture operation members 31U, 31L, 31R are at the reference position P0. From this state, in the first process, the posture operation member 31U is moved backward to the side where the acting force on the tip member 2 decreases, and the posture operation members 31L and 31R are moved forward to the side where the force acting on the tip member 2 is increased. As shown in FIG. 6B, the posture operation member 31U is retracted to the position P1a beyond the target position P1, and the posture operation members 31L and 31R are set to the position P2a before the target position P2. The positions P1a and P2a are obtained by testing or calculation. Next, as shown in FIG. 6C, in the second process, the posture operation member 31U is advanced and stopped at the target position P1, and the posture operation members 31L and 31R are advanced and stopped at the target position P2. This completes the posture change. 6A, 6B, and 6C are simplified views of the VI-CL2-VI cross section of FIG. The same applies to FIG. 9, FIG. 12, and FIG.

  FIG. 7 is a time chart showing changes in the base end positions of the posture operation members 31U, 31L, and 31R. FIG. 8 is a time chart showing the amount of displacement of the tip of the tip member 2. h is a target displacement amount of the tip member 2. In these figures, t1 is the first process end time, and t2 is the second process end time.

  According to this method, the displacement difference between the posture operation member 31U and the posture operation members 31L and 31R is temporarily increased by retracting the posture operation member 31U to the position P1a beyond the target position P1 in the first process. To do. Thereafter, in the second process, the posture operation members 31U, 31L, 31R move in the same direction to complete the operation. Thus, if each posture operation member 31U, 31L, 31R is moved in the same direction and the operation is completed, the direction of the friction force acting on each posture operation member 31U, 31L, 31R becomes constant, and the friction force The amount of expansion / contraction of each posture operation member 31U, 31L, 31R is also constant. Therefore, the posture change control of the tip member 2 can always be performed with constant accuracy.

  Note that when the retracting amount of the posture operation member 31U increases, the preload applied by the tip of the posture operation member 31U to the tip member 2 decreases, and the posture holding force of the tip member 2 decreases. Therefore, the position P1a for retracting the posture operation member 31U is set in consideration of the decrease in the preload.

A second method of posture change control will be described with reference to FIGS.
FIG. 9A shows a state before the bending operation. At this time, the posture of the distal end member 2 is the initial posture, and the base ends of the posture operation members 31U, 31L, 31R are at the reference position P0. From this state, in the first process, the posture operation member 31U is moved backward to the side where the acting force on the tip member 2 decreases, and the posture operation members 31L and 31R are moved forward to the side where the force acting on the tip member 2 is increased. As shown in FIG. 9B, the posture operation member 31U is retracted to the position P1a beyond the target position P1, and the posture operation members 31L and 31R are advanced to the target position P2. The position P1a is obtained by a test or calculation. Next, as shown in FIG. 9C, the posture operation member 31U is advanced and stopped at the target position P1 by the second process. This completes the posture change.

  FIG. 10 is a time chart illustrating changes in the base end positions of the posture operation members 31U, 31L, and 31R. FIG. 11 is a time chart showing the amount of displacement of the tip of the tip member 2. h is a target displacement amount of the tip member 2. In these figures, t1 is the first process end time, and t2 is the second process end time.

  This method is different from the first method in that the posture operation members 31L and 31R are moved to the target position P2 in the first process. Therefore, compared with the first method, it is possible to increase the displacement difference between the posture operation member 31U and the posture operation members 31L and 31R while alleviating the decrease in the preload of the tip member 2. Further, as in the first method, the direction of the frictional force acting on each posture operation member 31U, 31L, 31R can be made constant. Therefore, also by the second method, the posture change control of the tip member 2 can always be performed with a certain accuracy.

The 3rd method of attitude | position change control is demonstrated with FIGS.
FIG. 12A shows a state before the bending operation. At this time, the posture of the distal end member 2 is the initial posture, and the base ends of the posture operation members 31U, 31L, 31R are at the reference position P0. From this state, in the first process, the posture operation member 31U is moved backward to the side where the acting force on the tip member 2 decreases, and the posture operation members 31L and 31R are moved forward to the side where the force acting on the tip member 2 is increased. As shown in FIG. 12B, the posture operation member 31U is retracted to the position P1a beyond the target position P1, and the posture operation members 31L and 31R are set to the position P2a before the target position P2. Next, as shown in FIG. 12C, in the second process, the posture operation member 31U is advanced to the position P1b before the target position P1, and the posture operation members 31L and 31R are advanced to the target position. Stop at P2. The positions P1a, P1b, and P2a are obtained by testing or calculation. Further, only the posture operation member 31U is advanced and stopped at the target position P1 by the third process. This completes the posture change.

  FIG. 13 is a time chart showing changes in the base end positions of the posture operation members 31U, 31L, 31R. FIG. 14 is a time chart showing the amount of displacement of the tip of the tip member 2. h is a target displacement amount of the tip member 2. In these figures, t1 is the first process end time, t2 is the second process end time, and t3 is the third process end time.

  This technique is an intermediate control technique between the first technique and the second technique, and its actions and effects are also intermediate. Also in this case, since the direction of the frictional force acting on each posture operation member 31U, 31L, 31R can be made constant, the posture change control of the tip member 2 can always be performed with constant accuracy.

The 4th method of attitude | position change control is demonstrated with FIGS.
FIG. 15A shows a state before the bending operation. At this time, the posture of the distal end member 2 is the initial posture, and the base ends of the posture operation members 31U, 31L, 31R are at the reference position P0. From this state, in the first process, the posture operation member 31U is moved backward to the side where the acting force on the tip member 2 decreases, and the posture operation members 31L and 31R are moved forward to the side where the force acting on the tip member 2 is increased. As shown in FIG. 15B, the posture operation member 31U is retracted to the position P1a beyond the target position P1, and the posture operation members 31L and 31R are advanced at the position P2b beyond the target position P2. The positions P1a and P2b are obtained by testing or calculation. Next, as shown in FIG. 15C, in the second process, the posture operation member 31U is advanced and stopped at the target position P1, and the posture operation members 31L and 31R are moved backward and stopped at the target position P2. This completes the posture change.

  FIG. 16 is a time chart illustrating changes in the base end positions of the posture operation members 31U, 31L, and 31R. FIG. 17 is a time chart showing the amount of displacement of the tip of the tip member 2. h is a target displacement amount of the tip member 2. In these figures, t1 is the first process end time, and t2 is the second process end time. Here, in FIG. 17, the displacement amount of the tip position remains unchanged from t1 to t2, but remains unchanged, but if the settings of P1a and P2b are not appropriate, the displacement amount may increase or increase with time. is there.

  Unlike the second method, this method advances the posture operation members 31L and 31R to a position P2b beyond the target position P2 in the first process. Therefore, compared with the second method, the displacement difference between the posture operation member 31U and the posture operation members 31L and 31R can be increased while suppressing the amount of attenuation of the preload of the tip member 2, and the angle of the tip member 2 can be increased. The amount of bending can be increased. Also in this case, since the direction of the frictional force acting on each posture operation member 31U, 31L, 31R can be made constant, the posture change control of the tip member 2 can always be performed with constant accuracy.

  Note that if the amount of advancement of the posture operation members 31L and 31R at the end of the first process is too large, the tip member 2 may be bent beyond the target angle θ temporarily. Therefore, the position P2b for moving the posture operation members 31L and 31R forward is set in consideration of the temporary increase of the tip member 2. Note that the angle θ is the angle of the tip member 2 when the amount of displacement of the tip of the tip member 2 is h.

  During the posture change control, the movement amount of the posture control drive source 42 detected by the movement amount detector 46 is fed back to the posture change control unit 53b to perform control. When the motion amount detector 46 is provided, the motion amount of the posture control drive source 42 can be accurately detected, and the posture change control is accurately performed by feeding back the output to the posture change control unit 53b. It can be carried out.

  The external force estimating means 54 has relation setting means (not shown) in which the relation between the external force acting on the tip member 2 and the output signal of the strain sensor 47 is set by an arithmetic expression or a table. The external force acting on the tip member 2 is estimated from the signal obtained using the relationship setting means.

The operation of this remote control type actuator will be described.
When the tool rotation drive source 41 is driven, the rotation is transmitted to the spindle 13 via the rotation shaft 22, and the tool 1 rotates together with the spindle 13. The rotating tool 1 cuts bones and the like. When the tip member 2 is in an initial posture in a stationary state, each posture control drive source 42 is controlled by the initial posture holding control unit 53a, and an initial posture holding force is applied to each posture operating member 31. Thereby, the balance of the force acting on the tip member 2 is maintained, and the posture of the tip member 2 is maintained.

  At the time of use, the posture change control unit 53b controls the posture change drive source 42 to change the posture of the tip member 2. Any one of the first to fourth methods is applied to the posture change control of the tip member 2, but there is no difference in the amount of movement of the tip of each posture operation member 31 by any method. Therefore, the posture change control of the tip member 2 can always be performed with constant accuracy. The posture of the tip member 2 is detected by the posture detection means 46 from the detection value of the movement amount detector 45. Therefore, the posture of the tip member 2 can be appropriately controlled by remote operation.

  When an external force is applied to the tool 1 or the tip member 2 during the cutting process, the force is transmitted to the lever 43b of the force increase transmission mechanism 43 via the posture operation member 31, and distortion is generated in the strain generating portion 43ba which is a weak portion of the lever 43b. Arise. This distortion is detected by the distortion sensor 47, and the output signal is transmitted to the external force estimation means 54. The external force estimating means 54 estimates the external force acting on the tip member 2 from the output signal of the strain sensor 47. By controlling the feed amount of the entire remote operation type actuator and the posture change of the tip member 2 according to the magnitude of the external force estimated in this way, the external force acting on the tip member 2 can be maintained safely while maintaining the appropriate external force. And bone cutting can be performed accurately.

  Further, since the rotation preventing mechanism 37 for preventing the tip member 2 from rotating around the center line CL1 of the tip member 2 with respect to the spindle guide portion 3 is provided, the posture operation for controlling the forward and backward movement of the posture operation member 31 is provided. Even when the tip member 2 that holds the tool 1 becomes uncontrollable due to a failure of the drive mechanism 4c or the posture control means 53, the tip member 2 rotates around the center line CL1 and damages around the machining location. The tip member 2 itself can be prevented from being damaged.

  Since the posture operation member 31 is inserted through the guide hole 30a, the posture operation member 31 does not shift in the direction intersecting the longitudinal direction, and can always act properly on the tip member 2, and the tip member 2 posture change operation is performed accurately. Further, since the posture operation wire 31a constituting the posture operation member 31 is flexible, the posture changing operation of the tip member 2 is reliably performed even when the spindle guide portion 3 has a curved portion. Furthermore, since the center of the connecting portion between the spindle 13 and the rotating shaft 22 is at the same position as the center of curvature O of the guide surfaces F1 and F2, a force for pushing and pulling against the rotating shaft 22 by changing the posture of the tip member 2 is increased. Accordingly, the posture of the tip member 2 can be changed smoothly.

  This remote-operated actuator is used for, for example, cutting the bone medullary cavity in an artificial joint replacement operation, and all or part of the distal end member 2 is inserted into the patient's body during the operation. For this reason, if the posture of the tip member 2 can be changed by remote control as described above, the bone can be processed while the tool 1 is always held in an appropriate posture, and the artificial joint insertion hole is finished with high accuracy. Can do.

  The elongated spindle guide portion 3 needs to be provided with the rotating shaft 22 and the posture operation member 31 in a protected state. The rotating shaft 22 is provided at the center of the outer pipe 25, and the outer pipe 25, the rotating shaft 22, Since the guide pipe 30 accommodating the posture operation member 31 and the reinforcing shaft 34 are arranged side by side in the circumferential direction, the rotary shaft 22 and the posture operation member 31 are protected and the inside is hollowed out. It is possible to secure rigidity while reducing the weight. Also, the overall balance is good.

  Since the outer diameter surface of the rolling bearing 26 that supports the rotating shaft 22 is supported by the guide pipe 30 and the reinforcing shaft 34, the outer diameter surface of the rolling bearing 26 can be supported without using extra members. Moreover, since the preload is applied to the rolling bearing 26 by the spring elements 27A and 27B, the rotating shaft 22 made of a wire can be rotated at a high speed. Therefore, machining can be performed by rotating the spindle 13 at a high speed, the machining finish is good, and the cutting resistance acting on the tool 1 can be reduced. Since the spring elements 27A and 27B are provided between the adjacent rolling bearings 26, the spring elements 27A and 27B can be provided without increasing the diameter of the spindle guide portion 3.

  In the above-described embodiment, the guide pipe 30 and the posture operation member 31 are provided at three locations in the circumferential direction. However, the guide pipe 30 and the posture operation member are provided at two locations in the outer pipe 25 that are 180 degrees in phase with each other. It is good also as a structure which provided 31 (not shown). In that case, the posture of the tip member 2 can be changed only around one axis.

  In the above embodiment, the spindle guide portion 3 has a linear shape. However, in the remote control type actuator of the present invention, the posture operation member 31 is flexible, and the posture of the tip member 2 can be changed even when the spindle guide portion 3 is curved. Since the operation is reliably performed, the spindle guide portion 3 may be curved in the initial state. Alternatively, only a part of the spindle guide portion 3 may be curved. If the spindle guide portion 3 is curved, it may be possible to insert the distal end member 2 to the back of the bone, which is difficult to reach in the straight shape, so that the hole for artificial joint insertion can be accurately processed in artificial joint replacement surgery. It becomes possible to finish. When the spindle guide portion 3 has a curved shape, the outer pipe 25, the guide pipe 30, and the reinforcing shaft 34 need to have a curved shape. The rotating shaft 22 is preferably made of a material that is easily elastically deformed. For example, a shape memory alloy is suitable.

DESCRIPTION OF SYMBOLS 1 ... Tool 2 ... Tip member 3 ... Spindle guide part 5 ... Controller 13 ... Spindle 15 ... Tip member connection part 22 ... Rotating shaft 30a ... Guide hole 31 ... Posture operation member 31a ... Intermediate force transmission member 31b ... Tip force transmission member 31c ... Base force transmission member 41 ... Tool rotation drive source 42 ... Posture change drive source 53 ... Posture control means 53b ... Posture change control section CL1 ... Spindle center line CL2 ... Rotating shaft centerlines F1 and F2 ... Guide surface O ... Center of curvature P0 ... Reference position P1 ... Target position P2 ... Target position

Claims (11)

An elongated spindle guide portion, a tip member attached to the tip of the spindle guide portion via a tip member connecting portion so that the posture can be freely changed, a tool rotatably provided on the tip member, and a tool for rotating the tool A tool rotation drive source; and a posture change drive source for operating the posture of the tip member;
The tip member rotatably supports a spindle that holds the tool, and the spindle guide portion includes a rotation shaft that transmits the rotation of the tool rotation drive source to the spindle, and guide holes that penetrate both ends. A flexible posture operation member, which has an inner end and moves forward and backward by contacting and moving the tip member in contact with the tip member, is inserted into the guide hole so as to freely move forward and backward. A remote-operated actuator that moves forward and backward with a posture-changing drive source,
An attitude control means for controlling the attitude change drive source is provided, and the attitude control means follows a predetermined rule when performing control to move the attitude operation member from a reference position that is an operation start position to a target position. A remote operation type actuator comprising a step of temporarily moving a posture operation member to a side away from a target position.   2. The posture operation member according to claim 1, wherein the posture operation member includes a rigid distal force transmission member disposed on the distal member side, a rigid proximal force transmission member disposed on the posture change drive source side, and the distal force. A remote operation type actuator comprising a flexible and long intermediate force transmission member for transmitting a force between a transmission member and a proximal force transmission member.   3. The posture control means according to claim 1, wherein the posture control means moves the posture operation member beyond the target position when moving the posture operation member from a reference position to a target position where the acting force on the tip member decreases. A remote operation type actuator for controlling the posture changing drive source so as to return to the target position.   4. The guide member according to any one of claims 1 to 3, wherein the tip member changes its posture along a cylindrical or spherical guide surface of the tip member connecting portion. The posture operation members inserted through the guide surfaces are provided at a plurality of locations around the center of curvature of the guide surface, the posture change drive source is provided individually for each posture operation member, and the tips of the plurality of posture operation members are provided. A remote control type actuator that changes and maintains the posture of the tip member by balancing the acting forces on the member.   5. The posture control unit according to claim 4, wherein when the plurality of posture operation members are moved from the reference position to the target positions, the posture control members move in the same direction to complete the operation. Remote control actuator that controls the drive source for change.   6. The posture control means according to claim 4, wherein when the plurality of posture operation members are moved from the reference position to the respective target positions, the posture operation members are moved to positions beyond the target position for each posture operation member. A remote operation type actuator for controlling the posture changing drive source so as to return to the target position.   7. The remote operation type actuator according to claim 4, wherein the posture control means controls the posture changing drive source so as to drive each posture operation member in synchronization.   5. The posture operation according to claim 4, wherein when the plurality of posture operation members are moved from the reference position to their respective target positions, the posture control means moves the force acting on the tip member to an increasing side in the first step. Move the member to a position before the target position, and move the attitude control member that moves to the side where the acting force on the tip member decreases to the position beyond the target position, and in the second step, act on the tip member. A remote operation type actuator that controls the posture changing drive source so that a posture control member that moves to a side where force increases and a posture control member that decreases decrease to a target position.   5. The posture operation according to claim 4, wherein when the plurality of posture operation members are moved from the reference position to their respective target positions, the posture control means moves the force acting on the tip member to an increasing side in the first step. The posture operating member that moves the member to the target position and moves to the side where the acting force on the tip member decreases is moved to a position beyond the target position, and the acting force on the tip member decreases in the second process. A remotely operated actuator for controlling the posture changing drive source so as to move a posture control member to be moved to a target position.   5. The posture operation according to claim 4, wherein when the plurality of posture operation members are moved from the reference position to their respective target positions, the posture control means moves the force acting on the tip member to an increasing side in the first step. Moving the member to the first front position before the target position and moving the posture operating member to the side where the acting force on the tip member is reduced to a position beyond the target position, and in the second step, The posture control member that moves the posture operating member that moves to the side where the acting force on the tip member increases to the target position and moves the posture control member that moves to the side where the acting force on the tip member decreases decreases before the first target position. The posture control member is moved to the second front position closer to the target position than the front position and moved to the side where the acting force on the tip member decreases in the third process. In the remote controlled actuator which controls the attitude altering drive source to move.   5. The posture operation according to claim 4, wherein when the plurality of posture operation members are moved from the reference position to their respective target positions, the posture control means moves the force acting on the tip member to an increasing side in the first step. Move the member to a position beyond the target position and move the posture operating member to the position where the acting force on the tip member decreases to the position beyond the target position. A remote operation type actuator for controlling the posture changing drive source so as to move a posture operation member to be moved to a force increasing side and a posture control member to be moved to a decreasing side to respective target positions.

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