JP5647436B2 - Stepping actuator - Google Patents

Description

  The present invention relates to a power source for a surgical robot under a high magnetic field environment such as MRI (Magnetic Resonance Imaging) in medical engineering, and a stepping actuator that can be used in an evaluation research environment that is easily affected by electromagnetic waves.

  MRI has no danger of radioactive exposure, and is widely used as a medical imaging method having various visualization functions. In recent years, the opening of MRI with an enlarged MRI opening has made it possible to acquire MRI images during surgery. As a result, an MRI-guided operation has been proposed that realizes an accurate operation by performing an operation while visualizing an affected area by MRI.

  In order to realize a system for MRI-guided surgery, it is necessary to satisfy the following three constraints (problems) called MR Compatibility.

1) The system does not present a safety problem due to the influence of the magnetic field environment generated by the MRI (such as being not attracted to the MRI static magnetic field magnet).
2) System operation is not hindered by magnetic fields and electromagnetic waves generated by MRI.
3) The system does not adversely affect the acquired image of MRI such as noise and distortion.

  With respect to this constraint, the actuator part is particularly problematic when constructing a system. An electric motor using a normal electromagnetic force (such as a commutator motor or a synchronous motor) cannot be operated by a strong magnetic field generated by MRI.

  Therefore, many nonmagnetic ultrasonic motors that can operate even in a strong magnetic field have been used. However, there is a problem that an electromagnetic wave caused by a current as a power source adversely affects the MRI image. In addition, accurate and reproducible positioning is difficult. Therefore, a stepping motor using fluid pressure such as water pressure or air pressure has been recently reported. However, the hydraulic pressure stepping motor represented by Non-Patent Document 1, Non-Patent Document 2, and the like has a problem that it requires a lot of parts and lacks maintainability and practicality because its operation mechanism is complicated. Furthermore, the stepping motor of Non-Patent Document 2 is not intended for use in a high magnetic field environment and is not demagnetized. In addition, the stepping motor of Non-Patent Document 3 that has realized the operation with a simpler mechanism has also been proposed, but the rotational accuracy, rotational speed, and rotational torque of the mechanism are inferior to those of other products, so the structure is simple. There is no stepping motor that uses fluid pressure that balances performance with performance.

Dan Stoianovici, et.al., A New Type of Motor: Pneumatic Step Motor, IEEE / ASME TRANSACTIONS ON MECHATRONICS, VOL.12, NO.1: 98-106, FEBRUARY 2007 Kazuo Uzuki, et.al., Comparative Assessment of Several NutationMotor Types, IEEE / ASME TRANSACTIONS ON MECHATRONICS, VOL.14, NO. 1: 82-92, FEBRUARY 2009 Tomoki Hamada, et al .: Basic development of MRI image-guided puncture support manipulator using pneumatic sawtooth rotary actuator, J JSCAS, vol.10, no.3: 337-338, JANUARY 2008

  An object of the present invention is to provide a non-magnetic fluid pressure type stepping actuator that is intended to be used in an environment where high magnetic fields such as MRI and the like do not like electromagnetic waves. Another object of the present invention is to devise an operation mechanism that can be reduced in size, has a small number of parts, and is easy to maintain, and provides a new hydraulic stepping actuator that achieves both performance and ease of manufacture.

  A stepping actuator that achieves the above object is provided by the following configuration of the present invention.

(1) At least three or more N first drive members, second drive members, third drive members. . . A plurality of driving members comprising an Nth driving member and one driven member, wherein the plurality of driving members are housed in respective housing portions of the intermediate housing, and the driven member is housed in the upper housing;
Wherein each of the drive member comprises a second sliding surface in the same number as that of said first sliding surface and the first slide surface inclined in multiple, top or valley by the first sliding surface and the second sliding surface Tonaria' is formed And
The driven member comprises a first second object slide surface of the same number as the first target slide surface and the slide surface that is inclined obliquely, top or valley by the first target slide surface and the second object slide surface which Tonaria' Formed,
The first slide surface and the first slide surface are inclined in the same direction, and the second slide surface and the second slide surface are inclined in the same direction. And the interval between adjacent valleys in the driven member is the same,
When the first driving member is pushed in the direction of the driven member by fluid pressure, the first sliding surface of the driven member slides on the first sliding surface of the first driving member, and the valley of the driven member. The driven member is rotated until the top of the first drive member is engaged or the top of the driven member is engaged with the trough of the first member ;
The pushing of the driving member in the direction of the driven member by the fluid pressure is performed from the first driving member to the second driving member, from the second driving member to the third driving member, from the third driving member . . . The stepping actuator is characterized in that the driven member is rotated in the same direction by sequentially performing the N-th driving member and the N-th driving member to the first driving member.

(2) The stepping actuator according to (1), wherein the amount of rotation of the driven member is adjusted by increasing or decreasing the number of the plurality of driving members.
(3) When the second driving member is pushed in after the first driving member, the first sliding surface of the first driving member slides on the driven member first sliding surface as the driven member rotates. it is, automatically the first drive member is pushed back, Similarly, successively the N-th driving member from the second driving member, automatically pushed back and said Rukoto, according to (1) or (2) Stepping actuator.

  According to the present invention, it is possible to provide a stepping actuator that operates with only fluid pressure and does not use electromagnetic force and has high rotational accuracy and high rotational speed with only a few parts that are easy to manufacture. Become.

Explanatory drawing which shows the fundamental structure of the stepping actuator by this invention Explanatory diagram for explaining the operation of the stepping actuator Stepper actuator perspective view Sectional drawing which follows the AA line of FIG. Disassembled perspective view of stepping actuator Front view of intermediate housing Perspective view of the driven member from obliquely below Perspective view of drive member

  Hereinafter, a stepping actuator according to the present invention will be described with reference to the accompanying drawings.

  First, the operation principle of the stepping actuator according to this embodiment will be described with reference to the drawings.

  As shown in FIG. 1, the stepping actuator of this embodiment includes a first drive member 2, a second drive member 3, a third drive member 4, and a driven member 1.

  The first drive member to the third drive member are housed one by one in the first housing portion 61 to the third housing portion 63 of the intermediate housing 6 (see FIG. 6), and the operation is limited only in the linear motion direction. Yes. The driven member 1 is housed in the upper housing 5 (see FIG. 5), and can only perform a rotating operation.

Each of the driving members 2 to 4 includes a plurality of and the same number of inclined first slide surfaces 21, 31, 41 and second slide surfaces 22, 32, 42, and the adjacent first slide surface and second slide surface. The top part or trough part is formed. Similarly, the driven member 1 comprises a first target slide surface 11 which is and inclination of the same number of a plurality of second object slide surface 12, the first to be sliding surface 11 which Tonaria' top by a second object slide surface 12 or A valley is formed.

  The first slide surface (21, 31 or 41) and the first slide surface 11 are inclined in the same direction, and the second slide surface (22, 32 or 42) and the second slide surface 12 are the same. The distance between adjacent top portions of the drive members (2 to 3) and the distance between adjacent valley portions of the driven member are the same, and the drive member and the driven member are configured to engage with each other.

  In the state of FIG. 2A in which the third driving member 4 and the driven member 1 are completely engaged, the first piston 81 (see FIG. 5) passes through the first tube connecting portion 71 (see FIG. 3). When pushed by the fluid pressure sent, the first piston 81 pushes the pressing surface of the first drive member 2 toward the driven member 1 through the first piston passage 64 (see FIG. 6) of the intermediate housing 6.

  The drive member and the piston can be integrated with each other.

  When the first drive member 2 is pushed in, as shown in FIG. 2B, the second slide surface 22 of the first drive member 2 and the second slide surface 12 of the driven member (see FIG. 1) contact each other. Further, when the first drive member 2 is pushed in, the driven member 1 starts to rotate so that the second slide surface 12 of the driven member of the second drive surface 2 of the first drive member 2 follows. The driven member 1 rotates clockwise until the tops of the first driving members coincide, that is, until the driven member 1 and the first driving member 2 are completely engaged (see FIG. 2C).

  Similarly, when the second driving member 3 is pushed in by the second piston 82 from the state of FIG. 2A, the driven member rotates counterclockwise. Thus, the direction of rotation can be switched by switching the piston to be pushed. However, only the right rotation will be described below.

  When the fluid pressure is being sent to the first tube connecting portion 71, the fluid pressure is not being sent to the second tube connecting portion 72 and the third tube connecting portion 73, and therefore, with the rotation of the driven member, The second drive member 3 and the third drive member 4 are pushed back along the first sliding surface 11 of the driven member 1.

  Here, the second drive member 3 is completely separated from the driven member 1 by being pushed back (see FIG. 2C).

  Next, when the fluid pressure is sent to the second tube connection portion 72 this time, the second slide surface of the driven member 1 and the second slide surface 32 of the second drive member 3 come into contact with each other as before ( By further pushing, the driven member rotates clockwise until the valley of the driven member 1 coincides with the top of the second drive member 3 (see FIG. 2 (e)).

  From the state in which the first driving member 2 and the driven member 1 are completely engaged (FIG. 2 (c)) to the state in which the second driving member 3 and the driven member 1 are completely engaged (FIG. 2 (e)), The amount of displacement in the rotation of the driven member can be regarded as the amount of rotation for one step.

  As described above, since the top of the drive member and the valley of the driven member are engaged with each other, the distance between the tooth tips of the driven member 1 and the drive member (2, 3 or 4) (the distance between the adjacent tops). Are equal to each other, and if the number of teeth of the driven member is T and the distance between the tooth tips is D degrees, D = 360 / T is established. The stepping actuator includes one driven member and three or more driving members. The number of the drive members is N (integer N ≧ 3), and the adjacent drive members are arranged in the storage portion in the intermediate housing with an interval of D / N degrees. At this time, the number of teeth of the drive member is (T-1) / N. As a result, when all the driving members are pushed in order and complete a cycle, the driven member rotates by D degrees. Therefore, the displacement amount that the driven member rotates every time the driving member is pushed once becomes D / N degrees, and this can be regarded as the displacement amount for one step.

  Therefore, in order to satisfy the above relationship, the first drive member 2, the second drive member 3, and the third drive member 4 have a tooth tip interval (interval between adjacent top portions of the drive member) of 3 minutes in the intermediate housing. Therefore, the amount of rotation in one step is one third of the tooth tip interval.

  The amount of rotation for one step is one third of the tooth tip interval when three drive members are used, and the amount of rotation for one step is calculated when N (N ≧ 3) drive members are used. It can be 1 / N of the previous interval.

  For example, when T = 10 and N = 3, the number of teeth of the drive member is three as shown in FIG. 1, and the three drive members are arranged in the intermediate housing with an interval of 12 degrees. The amount of rotation of the driven member when the second driving member is pushed in after the first driving member is 12 degrees, which can be regarded as the amount of displacement for one step.

  Therefore, the accuracy of rotation can be increased by increasing the number of driving members to be configured. Of course, it is also possible to improve the rotation accuracy by increasing the number of teeth of the driving member and the driven member.

  Therefore, the rotation accuracy can be further increased by reducing the interval between the tooth tips (increasing T). Further, the rotational accuracy can be increased by increasing the number of drive members configured (increasing N).

  When the third driving member 4 is further pushed in from the state of FIG. 2 (e), the first driving member 2 is completely separated from the driven member 1 as shown in FIG. 2 (f), and the second driving member 3 is driven member. With the rotation of 1, it is pushed back from the state of being completely engaged. The state of FIG. 2 (f) is the same as the state of FIG. 2 (a), and the driven member 1 is the same by repeating the pushing operation by the fluid pressure from the first drive member 2 to the third drive member 4 in a series. Rotation in the direction is realized.

  Further, the driving member and the driven member can be stopped in a state where they are completely engaged, and a holding torque can be generated.

  According to the present invention, if the pushing operation of the drive member is repeated in the order of the first drive member, the second drive member, and the third drive member, the driven member rotates clockwise, and the third drive member and the second drive If it repeats in order of a member and the 1st drive member, a follower member will rotate counterclockwise. That is, the rotation direction of the driven member can be switched by switching the order in which the driving member is pushed.

  Further, the pushing operation of the driving member can be realized by fluid pressure, and even when used in an MRI environment, there is an advantage that the operation of the MRI apparatus is hardly affected.

  And the displacement amount of the drive member in the pushing operation at that time is from the state where the top of the drive member is below the top of the driven member (initial state) until the top of the drive member completely engages with the valley of the driven member. (Completed state). By minimizing the distance of the gap between the top of the driving member and the top of the driven member in the initial state, the amount of displacement of the driving member can be minimized. Thereby, high-speed operation is possible.

  Further, since the driving member and the driven member are completely engaged with each other, there is almost no backlash in rotation.

  When the second driving member is pushed in after the first driving member, the first sliding surface of the first driving member slides on the driven member first sliding surface as the driven member rotates. The first drive member is pushed back. Therefore, it is possible to realize the rotational operation of the driven member simply by pushing the driving member in order only with the positive pressure of the fluid pressure.

  As described above, the operation of pushing back the driving member is performed with the rotation of the driven member, so that the amount of pushing back of the driving member can be minimized.

  Further, the pushing-back operation of the driving member is performed with the rotation of the driven member, and only the driving force of the pushing operation needs to be given to the driving member. As a result, when fluid pressure is used, a system can be constructed only with a device (such as a compressor) that generates positive pressure as a power source. Of course, it is also possible to realize a push-back operation by applying a negative pressure to the drive member.

  Existing pneumatic actuators are difficult to operate with low speed, high accuracy and reproducibility. This is mainly due to the compressibility of air and the operating principle of the actuator. In addition, existing fluid pressure type stepping actuators have complicated mechanisms and many components, so they are poor in maintainability and practicality. In the case of simple mechanisms, there are problems such as impaired rotation accuracy and rotation speed. It was. The present actuator solves these problems, and is considered to have a high industrial utility value because it is a fluid pressure actuator that can be applied to fields that were impossible in the past. Since the structure is simple, the barrier to practical use is low and it may be widely used in the future.

1 driven member 11 first slide surface 12 second slide surface 13 top 14 valley 2 first drive member 21 first slide surface 22 second slide surface 23 top 24 valley 25 pressing surface 3 second drive member 31 first 1 slide surface 32 2nd slide surface 33 top portion 34 valley portion 35 pressing surface 4 third drive member 41 first slide surface 42 second slide surface 43 top portion 44 valley portion 45 pressing surface 5 upper housing 6 intermediate housing 61 first storage portion 62 Second storage portion 63 Third storage portion 64 First piston passage 65 Second piston passage 66 Third piston passage 7 Lower housing 71 First tube connection portion 72 Second tube connection portion 73 Third tube connection portion 81 First piston 82 Second piston 83 Third piston 9 Rotating shaft

Claims (3)

At least three or more N first drive members, second drive members, third drive members. . . A plurality of driving members comprising an Nth driving member and one driven member, wherein the plurality of driving members are housed in respective housing portions of the intermediate housing, and the driven member is housed in the upper housing;
Wherein each of the drive member comprises a second sliding surface in the same number as that of said first sliding surface and the first slide surface inclined in multiple, top or valley by the first sliding surface and the second sliding surface Tonaria' is formed And
The driven member comprises a first second object slide surface of the same number as the first target slide surface and the slide surface that is inclined obliquely, top or valley by the first target slide surface and the second object slide surface which Tonaria' Formed,
The first slide surface and the first slide surface are inclined in the same direction, and the second slide surface and the second slide surface are inclined in the same direction. And the interval between adjacent valleys in the driven member is the same,
When the first driving member is pushed in the direction of the driven member by fluid pressure, the first sliding surface of the driven member slides on the first sliding surface of the first driving member, and the valley of the driven member. The driven member is rotated until the top of the first drive member is engaged or the top of the driven member is engaged with the trough of the first member ;
The pushing of the driving member in the direction of the driven member by the fluid pressure is performed from the first driving member to the second driving member, from the second driving member to the third driving member, from the third driving member . . . The stepping actuator is characterized in that the driven member is rotated in the same direction by sequentially performing the N-th driving member and the N-th driving member to the first driving member.   The stepping actuator according to claim 1, wherein the amount of rotation of the driven member is adjusted by increasing or decreasing the number of the plurality of driving members. When the second driving member is pushed in after the first driving member, the first sliding surface of the first driving member slides on the driven member first sliding surface as the driven member rotates. automatically the first driving member is pushed back, Similarly, successively the N-th driving member from the second driving member, automatically pushed back and said Rukoto, stepping actuator according to claim 1 or 2.

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