WO2016035564A1 - Link actuating device - Google Patents

Abstract

A link actuating device having triple-jointed chain link mechanisms (L1-L3) comprising four rotating pairs, said mechanisms (L1-L3) being configured from a proximal-end-side end link (3) that is linked in a rotatable manner at one end to a proximal-end side link hub (1), a distal-end-side end link that is linked in a rotatable manner at one end to a distal-end-side link hub, and a center link (5) that is linked in a rotatable manner to the other end of the proximal-end-side end link (3) and the other end of the distal-end-side end link; the distal-end-side link hub being linked to the proximal-end-side link hub (1) via the link mechanisms (L1-L3) in a manner allowing the orientation to be changed; wherein the difference in the circumferential separation angles (δ3- δ1) of the proximal-end-side end link (3) of the link mechanism (L1) and the proximal-end-side end link (3) of the link mechanism (L3) is 180°, this set of two link mechanisms (L1, L3) is provided with rotary encoders (12) for detecting the rotation angle of the proximal-end-side end links (3), and a controller (28) for defining the orientation of the distal-end-side link hubs on the basis of the rotation angle obtained by the rotary encoder (12).

Description

Link actuator

The present invention relates to a link operating device having a parallel link mechanism incorporated in precision equipment such as medical equipment and industrial equipment that requires a wide operating range.

For example, there is a working device equipped with a parallel link mechanism that performs high-speed and precise operations such as complex processing and article handling in a three-dimensional space (see, for example, Patent Document 1).

The working device disclosed in Patent Document 1 includes a parallel link mechanism that changes the position and posture of the traveling plate with respect to the base plate by cooperatively expanding and contracting a plurality of links connecting the base plate and the traveling plate. By attaching a tool to the traveling plate of this parallel link mechanism and rotatably arranging a table to hold the workpiece, the position and posture of the tool with respect to the workpiece on the table can be freely changed. It enables complex processing and handling of articles in the space.

With the parallel link mechanism in this working device, the mass of the movable part can be reduced, and the positioning error of each link is averaged at the tip, and complicated processing in the three-dimensional space, handling of articles, etc. It has a great feature in performing the above work at high speed and precision.

JP 2000-94245 A US patent US5893296A JP 2005-69462 A

By the way, in the parallel link mechanism in the working device disclosed in Patent Document 1, since the operating angle of each link is small, it is necessary to increase the link length when attempting to set the operating range of the traveling plate large. Thereby, there exists a problem that the dimension of the whole mechanism becomes large and causes the enlargement of an apparatus. In addition, if the link length is increased, the rigidity of the entire mechanism is lowered, so that there is a problem that the weight of the tool mounted on the traveling plate, that is, the loadable weight in the traveling plate is limited to a small one. For the above reasons, it is difficult to apply to a precision medical device or the like that requires a wide operating range while having a compact configuration.

In order to solve the above-described problems, a link actuating device that has a compact configuration and enables precise operation in a wide operating range has been proposed (for example, see Patent Document 2).

The link actuating device disclosed in Patent Document 2 includes a proximal end link that is rotatably connected to a proximal link hub, and a distal end that is rotatably connected to a distal link hub. And a central link in which the proximal end link and the distal end link are rotatably connected to each other, and has a three-joint link mechanism composed of four rotary pairs. By having such a structure, it is easy to realize application to a precision medical device or the like that requires a wide operation range with a compact configuration.

However, the link actuating device disclosed in Patent Document 2 controls the rotational position of the base end side end link. However, the control method is not disclosed, and the base end side end portion is also disclosed. The control means for obtaining the attitude of the distal end side link hub with respect to the rotation angle input to the link and for obtaining the rotation angle of the proximal end link with respect to the attitude input to the distal side link hub is disclosed. It has not been.

Accordingly, the present applicant obtains the attitude of the distal end side link hub with respect to the rotation angle input to the proximal end side end link, or the rotation of the proximal end side end link with respect to the attitude input to the distal end side link hub. In order to obtain the angle, a link actuating device that discloses a relational expression between the attitude of the distal end side link hub and the rotation angle of the proximal end side end link has been proposed (for example, see Patent Document 3).

The link actuating device disclosed in Patent Document 3 includes a rotation angle β of the base end side end link, an axis angle γ of the center link, and the circumference of each base end side end link with respect to the reference base end side end link. It is possible to control the attitude of the tip-side link hub by inverse transformation using a relational expression with the direction separation angle δ, the bending angle θ and the turning angle φ defining the attitude of the tip-side link hub as parameters, or according to the relational expression. The forward link hub can be detected by forward conversion.

However, in the link operating device disclosed in Patent Document 3, when the calculation is performed using the above-described relational expression as it is, for example, a convergence calculation or a case division is necessary, which requires a complicated calculation and a calculation time. Therefore, the responsiveness may be deteriorated. For this reason, the present situation is that it is desired to improve the responsiveness of the link actuating device in application to precision medical devices and the like.

Therefore, the present invention has been proposed in view of the above-described improvements, and the object of the present invention is to provide a link operating device excellent in responsiveness when applied to a precision medical device or the like. is there.

As technical means for achieving the above-described object, the present invention includes a proximal end link that is rotatably connected to the proximal link hub, and an end that is connected to the distal link hub. It is composed of a distal end side link that is rotatably connected, and a central link that is rotatably connected to the other end of the proximal end link and the other end of the distal end link. In a link operating device having at least three sets of three-link linkage mechanisms consisting of the above, and connecting the distal end side link hub to the proximal end side link hub via the link mechanism so that the posture can be changed. For the two sets of link mechanisms selected in the above, the difference in the circumferential separation angle between the base end side end link of one link mechanism and the base end side end link of the other link mechanism is 180 °. Paired link mechanism against proximal link hub An angle detection means for detecting the rotation angle of the proximal end link is provided, and an arithmetic means for defining the attitude of the distal link hub based on the rotation angle obtained by the angle detection means is provided. To do.

In the present invention, for the two sets of link mechanisms in which the difference in the circumferential direction separation angle between the base end side end link of one link mechanism and the base end side end link of the other link mechanism is 180 °, Only by detecting the rotation angle of the base end side end link with respect to the side link hub by the angle detection means, when the attitude of the front end side link hub is defined by the calculation means, the conventional complicated calculation such as convergence calculation and case classification No computation is required. Thus, since complicated calculation is not required, the calculation time can be shortened. Therefore, when the link operating device is applied to a precision medical device, the responsiveness of the link operating device can be improved. Further, since the angle detecting means only needs to be provided in the two sets of link mechanisms, the cost of the link operating device can be reduced and the size can be reduced.

In the present invention, the proximal end side link hub and the distal end side link hub connected to one end of the proximal end side end link and the distal end side end link are rotatably connected, the proximal end side end link, and the distal end side. It is desirable to add a configuration in which an angle formed by a connecting end axis of a central link in which the other end of the end link is rotatably connected is 90 °. If such a configuration is added, the connecting end axis of the base end side link hub and the front end side link hub and the connecting end axis of the center link are orthogonal to each other, so that the base end side end link and the front end side end link are manufactured. The workability at the time and the assemblability of the link mechanism are improved, and the calculation for detecting the posture of the distal end side link hub is further simplified.

In the present invention, it is desirable to add a configuration in which two or more sets of link mechanisms arbitrarily selected from the link mechanisms are provided with an actuator that arbitrarily changes the attitude of the distal end side link hub. If such a configuration is added, the posture of the distal end side link hub can be arbitrarily controlled by the actuator.

Also, it is desirable that the actuator includes an encoder that detects the rotation angle of the proximal end link relative to the proximal link hub. With such a configuration, not only can the encoder function as part of the means for controlling the attitude of the distal link hub, but it can also be used as the aforementioned angle detection means, so the apparatus can be made compact. . In addition, if this encoder is used, it is possible to exert a direct teaching function for manually determining the posture of the distal end side link hub.

According to the present invention, two sets of link mechanisms in which the difference in the circumferential direction separation angle between the base end side end link of one link mechanism and the base end side end link of the other link mechanism is 180 °. Just by detecting the rotation angle of the proximal end link relative to the proximal link hub by the angle detection means, when defining the attitude of the distal link hub by the computing means, the conventional convergence calculation and case classification Complicated calculations are not required. Thus, since complicated calculation is not required, the calculation time can be shortened. Therefore, when the link operating device is applied to a precision medical device, the responsiveness of the link operating device can be improved. Further, since the angle detecting means only needs to be provided in the two sets of link mechanisms, the cost of the link operating device can be reduced and the size can be reduced. As a result, a high-speed link actuator that is compact and excellent in responsiveness can be easily realized.

It is a front view which shows one set of link mechanisms provided with the angle detection means in embodiment of the link actuator which concerns on this invention. It is sectional drawing which shows the link actuator which consists of 3 sets of link mechanisms by which the angle detection means was provided in 2 sets of link mechanisms. It is a perspective view which shows the whole structure of the link action | operation apparatus of FIG. It is sectional drawing which shows the link actuator which consists of six sets of link mechanisms by which the angle detection means was provided in two sets of link mechanisms. It is a front view which shows the link actuator which consists of four sets of link mechanisms by which the actuator with an encoder was provided in two sets of link mechanisms. FIG. 6 is a cross-sectional view showing the link actuating device of FIG. 5.

Embodiments of the present invention are described in detail below. Figure 1 is a front view showing a set of the link mechanism L ₁ of the rotary encoder 12 is provided as an angle detecting means. FIG. 2 is a cross-sectional view showing a link actuating device including three sets of link mechanisms L ₁ to L _{3 in} which a rotary encoder 12 is provided in two sets of link mechanisms L ₁ and L ₃ . FIG. 3 is a perspective view showing the overall configuration of the link operating device of FIG. In FIG. 3, the rotary encoder 12 is omitted.

The link actuating device of the embodiment shown in FIG. 1 to FIG. 3 is incorporated in precision equipment such as medical equipment and industrial equipment that requires a wide working range, and performs operations such as complex processing and article handling in a three-dimensional space. Are provided with three sets of link mechanisms L ₁ to L _{3 each of} which is a parallel link mechanism that executes the operation at high speed and precisely.

Each of the three sets of link mechanisms L ₁ to L ₃ has the same geometric shape. _On the base end side of the link mechanisms L ₁ to L ₃ , there is provided a base end side link hub 1 that is attached to a fixing portion of a device in which the link actuating device is incorporated, for example, a base (not shown). Further, on the distal end side of the link mechanisms L ₁ to L ₃ , there is provided a distal end side link hub 2 to which a movable part of a device in which the link actuating device is incorporated, for example, a robot hand (not shown) is attached. This link actuating device has a structure in which a distal end side link hub 2 is connected to a proximal end side link hub 1 via link mechanisms L ₁ to L ₃ so that the posture can be changed.

The link mechanisms L ₁ to L ₃ have one end rotatably connected to the base end side link hub 1 and one end rotatably connected to the base end side link hub 2. The distal end side end link 4, the other end of the proximal end side end link 3 and the other end of the distal end side end link 4 are rotatably connected to each other. It has the following three-barrel structure. As described above, each of the link mechanisms L ₁ to L ₃ includes the two end links 3 and 4 and the one central link 5, and the proximal-side link hub 1 and the distal-side link hub 2 include three sets. Shared by the link mechanisms L ₁ to L ₃ . The base end side and the tip end side are geometrically symmetrical with respect to the cross section at the center of the link mechanisms L ₁ to L ₃ . In other words, when the plane of symmetry m of the central link 5 is divided into the proximal end side and the distal end side, the geometric shapes of the proximal end side and the distal end side are the same.

The proximal end side link hub 1 has a disk shape, and as shown in FIG. 2, one end of the proximal end side end link 3 is rotatably supported by support portions 6 provided at three locations in the circumferential direction. That is, by inserting the shaft portion 7 extending inward from one end of the base end side end link 3 into the support portion 6 via the bearing 8, the base end side end link 3 is made to the base end side link hub 1. It is supported rotatably. The connection structure between the distal end side link hub 2 and one end of the distal end side end link 4 is the same, and the distal end side end link 4 is rotatably supported by the support portion 9 with respect to the distal end side link hub 2 ( (See FIG. 1).

The proximal end link 3 and the distal end link 4 are L-shaped, and one end rotates on the proximal link hub 1 and the distal link hub 2 with the support portions 6 and 9 as described above. The other end is rotatably connected to the central link member 5. The center link 5 is inserted into the other end of the base end side end link 3 and the front end side end link 4 via a bearing 11 so as to integrally extend from both ends of the central link 5, whereby the base end side end link 3 and the distal end side end link 4 are rotatably connected. The coupling structure of the central link 5 to the proximal end link 3 and the distal end link 4 is as follows: the proximal link hub 1 (distal link hub 2) and the proximal end link 3 (distal end). This is the same as the coupling structure with the link 4).

The base end side end link 3 (front end side end link 4) is connected to one end of the base end side link hub 1 (front end side link hub 2) rotatably connected to one end of the base end side end link 3 and the base end side end link 3 The angle α formed by the connecting end axis of the central link 5 to which the other end of the (front end side end link 4) is rotatably connected, that is, the axis of the base end side end link 3 (front end side end link 4). The angle α is 90 °.

As a result, the connecting end axis of the base end side link hub 1 (front end side link hub 2) and the connecting end axis of the central link 5 are orthogonal to each other, so that the base end side end link 3 and the front end side end link 4 are manufactured. The workability at the time and the assemblability of the link mechanisms L ₁ to L ₃ are improved, and the calculation for detecting the attitude of the distal end side link hub 2 is further simplified as will be described later. In addition, in this embodiment, although the axial angle of the base end side end part link 3 (front end side end part link 4) is 90 degrees, values other than that may be sufficient.

Four rotation pairs in each of the link mechanisms L ₁ to L ₃ , that is, two connecting portions of the proximal end side link hub 1 and the proximal end side end link 3 and the distal end side link hub 2 and the distal end side end link 4 The base end side end link 3 and the central link 5 and the front end side end link 4 and the central link 5 are connected to each other to have a bearing structure, thereby reducing frictional resistance at the connecting portion and reducing rotational resistance. Thus, smooth power transmission can be ensured and durability can be improved.

3 sets of link mechanisms L _{1 ~} 2 sets arbitrarily selected from among L ₃ of the link mechanism L _1, the L _3, one link mechanism proximal end links L ₁ 3 and the other link mechanism L ₃ of circumferentially spaced angles [delta] ₁ of the base end side end link 3, the difference [delta] ₃ and ([delta] ₃ - [delta ₁₎ is set to 180 °. In this case, since the spacing angle [delta] ₁ of the link mechanism L ₁ of the proximal end link 3 is 0, to the separation angle [delta] ₃ of the link mechanism L ₃ of the proximal end link 3 and 180 ° become.

Here, the “separation angle δ” defines the circumferential position interval of each end link 3 with respect to the base end side end link 3 serving as a reference, and the base end side link hub of the base end side end link 3. 1 means an angle formed by each of the connecting end shafts. In this embodiment, it is based on the link mechanism L ₁ of the proximal end link 3. The difference (δ ₂ −δ ₁ ) between the separation angles δ ₁ and δ ₂ between the base end side end link 3 of the link mechanism L _{1 and} the base end side end link 3 of the link mechanism L ₂ , that is, the link mechanism spaced angle [delta] ₂ of the proximal end link 3 of L ₂ is set to 90 °.

The rotation of the base end side end link 3 relative to the base end side link hub 1 is performed by two sets of link mechanisms L ₁ and L _{3 in} which the difference (δ ₃ −δ ₁ ) between the separation angles δ ₁ and δ ₃ is 180 °. A rotary encoder 12 is provided as angle detection means for detecting the angle. As the angle detection means, a rotary encoder 12 is coaxially attached to the tip of a shaft portion 7 extending from the base end side end link 3 and protruding from the support portion 6 of the base end side link hub 1 via a coupling 13. Structure is adopted. By adopting such a structure, the rotation angle of the proximal end link 3 is directly detected by the rotary encoder 12.

In this embodiment, although the case where the base end side link hub 1 and the front end side link hub 2 make disk shape is illustrated, other shapes, such as a ring shape, may be sufficient. Depending on the shape of the base end side link hub 1, the rotary encoder 12 may be arranged outside the link mechanisms L ₁ and L ₃ in addition to the rotary encoder 12 inside the link mechanisms L ₁ and L ₃ as in this embodiment. Is also possible. In this embodiment, the rotary encoder 12 is employed as the angle detection means, but other sensors such as a distance measuring sensor and an inclination angle sensor can also be used.

In the embodiment described above, three sets of link mechanisms L ₁ to L ₃ are exemplified, but the number of sets of link mechanisms may be three or more. The reason why the number of link mechanisms is three or more is to provide a mechanism with two degrees of freedom between the base end side and the tip end side. FIG. 4 illustrates a link actuating device having six sets of link mechanisms L ₁ to L ₆ . Spaced angles [delta] ₁ ~ [delta] ₆ of the six sets of link mechanisms _L 1 ~ proximal side end link 3 in _{L 6 are, δ 1 = 0 °, δ} 2 = 60 °, δ 3 = 120 °, δ 4 = 180 °, δ ₅ = 240 °, and δ ₆ = 300 °. The basic configuration of the six sets of link mechanisms L ₁ to L ₆ is the same as that of the link mechanisms L ₁ to L ₃ of FIGS.

In this link actuating device, for the two sets of link mechanisms L ₁ and L ₄ arbitrarily selected from the six sets of link mechanisms L ₁ to L ₆ , the base end side end link 3 of _one link mechanism L ₁ is used. And the difference (δ ₄ −δ ₁ ) between the separation angles δ ₁ and δ ₄ between the base end side link 3 of the other link mechanism L ₄ and 180 °. The rotation of the base end side end link 3 relative to the base end side link hub 1 is performed by two sets of link mechanisms L ₁ and L _{4 in} which the difference (δ ₄ −δ ₁ ) between the separation angles δ ₁ and δ ₄ is 180 °. A rotary encoder 12 for detecting a corner is provided. In this embodiment, the rotary encoder 12 is disposed outside the link mechanisms L ₁ and L ₄ .

5 and 6 illustrate a link actuating device including four sets of link mechanisms L ₁ to L ₄ . The four sets of link mechanisms _L 1 ~ _L spaced angles [delta] ₁ ~ [delta] ₄ of the proximal end link 3 in _{4, δ 1 = 0 °, δ} 2 = 90 °, δ 3 = 180 °, δ 4 = It is 270 degrees. The basic configuration of the four sets of link mechanisms L ₁ to L ₄ is the same as that of the link mechanisms L ₁ to L ₃ of FIGS.

In this link actuating device, a shaft portion 15 extending integrally from a support portion 14 provided at one central position of the base end side link hub 1 is inserted into one end of the base end side end portion link 3 via a bearing 16. Thus, the base end side end links 3 of the link mechanisms L ₁ to L ₄ are commonly supported by the support portion 14 of the base end side link hub 1 so as to be rotatable. The connection structure of the distal end side link hub 2 and the distal end side end link 4 is the same, and the distal end side end link 4 is rotatably supported by the support portion 17 with respect to the distal end side link hub 2.

In this link actuating device, for the two sets of link mechanisms L ₁ and L ₃ arbitrarily selected from the four sets of link mechanisms L ₁ to L ₄ , the base end side end link 3 of _one link mechanism L ₁ is used. And the difference (δ ₃ −δ ₁ ) between the separation angles δ ₁ and δ ₃ between the second link mechanism L _{3 and} the base end side end link 3 is 180 °. With two sets of link mechanisms L ₁ and L ₃ having a difference (δ ₃ −δ ₁ ) of the separation angles δ ₁ and δ ₃ as 180 °, an encoder as a drive means for changing the attitude of the distal link hub 2 is provided. An actuator 18 is provided. In this embodiment, the actuators 18 are provided in the two sets of link mechanisms L ₁ and L _3. However, since the actuators may be provided in two or more sets of link mechanisms, the actuators are provided in the other link mechanisms L ₂ and L ₄ . 18 may be provided.

In the embodiment shown in FIGS. 1 to 3, of the three sets of link mechanisms L ₁ to L ₃ , two sets of the difference between the separation angles δ ₁ and δ ₃ (δ ₃ −δ ₁ ) are 180 °. An actuator may be provided in the link mechanisms L ₁ and L ₃ . Further, in the embodiment shown in FIG. 4, of the six sets of link mechanisms L ₁ to L ₆ , two sets of link mechanisms L in which the difference (δ ₄ −δ ₁ ) between the separation angles δ ₁ and δ ₄ is 180 °. ₁ and L ₄ may be provided with an actuator. In the link actuating device shown in FIGS. 1 to 4, since the rotary encoder 12 is provided, an actuator without an encoder may be provided.

As a driving means for the distal end side link hub 2, for the two sets of link mechanisms L ₁ and L ₃ , a fan-shaped large gear member 19 is attached to the proximal end side end link 3, and a small gear is disposed in the vicinity of the large gear member 19. The gear member 20 is disposed. The small gear member 20 has a shaft shape, and both end portions thereof are supported on the proximal end side link hub by the support member 22 via the bearings 21. The tooth portion formed on the outer periphery of the central portion of the small gear member 20 and the tooth portion formed on the end surface of the large gear member 19 are in mesh with each other. An actuator 18 is coaxially connected to one shaft end of the small gear member 20 via a coupling 23. The actuator 18 includes a speed reducer 24, a motor 25, and an encoder 26, and is fixed on the proximal end side link hub by a support member 27.

Since this actuator 18 includes an encoder 26 that controls the attitude of the distal end side link hub 2, the actuator 18 has not only a function of controlling the attitude of the distal end side link hub 2 but also the proximal end side link hub 1. Since it can be used together as an angle detecting means for detecting the rotation angle of the base end side end link 3, it is not necessary to provide the rotary encoder 12 on the base end side end link 3, and the link operating device can be made compact. . Further, if this encoder 26 is used, a direct teaching function for manually determining the posture of the distal end side link hub 2 can be exhibited.

In this embodiment, the driving force of the actuator 18 is transmitted by a gear, but other than this, a belt or a chain may be used. The actuator 18 may be directly driven by a cylinder. Alternatively, the motor may be directly attached to the shaft portion 15 of the proximal end side link hub 1 by using a coupling or the like. Further, as the rotary drive actuator 18, in addition to the motor described above, a linear actuator composed of a rack and a pinion can be used.

In each of the link mechanisms L ₁ to L ₃ in each of the embodiments described above, the geometric shapes of the proximal end link 3 and the distal end link 4 are the same on the proximal side and the distal side, When the shapes of the links 5 are the same on the proximal end side and the distal end side, the angular positional relationship between the central link 5 and the proximal end link 3 and the distal end link 4 with respect to the symmetry plane m of the central link 5. If the base end side and the front end side are the same, the base end side link hub 1 and the base end side end link 3 and the front end side link hub 2 and the front end side end link 4 are the same because of geometric symmetry. And the base end side and the tip end side rotate at the same rotational angle with the same rotation angle.

The symmetry plane m of the central link 5 during the constant speed rotation is referred to as a uniform speed bisector. Therefore, by arranging a plurality of identical linkage geometry L _{1 ~} L ₃ sharing the proximal link the hub 1 and the distal end side link hub 2 on the circumference, a plurality of link mechanisms L _{1 ~} L ₃ The center link 5 is limited to the movement on the uniform bisecting plane as a position where it can move without contradiction, and thereby, even if the base end side and the distal end side take any operating angle, constant speed rotation can be obtained.

Hereinafter, the link actuating device including the three sets of link mechanisms L ₁ to L ₃ shown in the embodiment of FIGS. 1 to 3 will be described. The six sets of link mechanisms L ₁ to L ₆ shown in the embodiment of FIG. The same applies to the link actuator provided with the link actuator and the link actuator provided with the four sets of link mechanisms L ₁ to L ₄ shown in the embodiment of FIGS.

In the link actuating device shown in FIGS. 1 to 3, the posture of the distal end side link hub 2 can be defined by two degrees of freedom (folding angle θ and turning angle φ), and the posture of the distal end side link hub 2 (folding angle). The relationship between θ and the turning angle φ) and the rotation angle β of the proximal end link 3 detected by the rotary encoder 12 can be defined by the following equation. The link actuating device includes a control unit 28 (see FIG. 1) as calculation means that can detect the attitude of the distal link hub 2 by conversion according to the following relational expression. The rotary encoder 12 provided in the link mechanisms L ₁ and L ₃ is connected to the input of the controller 28, and the actuator (not shown) provided in the link mechanisms L ₁ and L ₃ is connected to the output of the controller 28. Connected).

Here, the “bending angle θ” is a vertical angle in which the central axis of the distal end side link hub 2 is inclined with respect to the central axis of the proximal end side link hub 1, and the “turning angle φ” is the proximal end side link. This means a horizontal angle in which the central axis of the distal link hub 2 is inclined with respect to the central axis of the hub 1. “Rotation angle β” means the rotation angle of the connecting end of the base end side end link _{3 with} respect to the base end side link hub 1 for the three sets of link mechanisms L ₁ to L ₃ . “Conversion by relational expression” means that by inputting a target value that defines the rotation angle of the base end side end link 3 of the base end side link hub 1 into the relational expression, the distal end side link hub 2 with respect to the rotation angle input. Is obtained by calculation processing in the control unit 28.

In this link actuating device, the phase of the connecting end shaft of the base end side link hub 1 in the reference link mechanism L ₁ among the three sets of link mechanisms L ₁ to L ₃ is set to a turning angle φ = 0. At this time, when the axial angle of the central link 5 is γ, and the circumferential separation angle of each proximal end link 3 with respect to the proximal end link 3 of the reference link mechanism L ₁ is δ, the separation angle In the link mechanisms L ₁ and L ₃ in which the difference (δ ₃ −δ ₁ ) between δ ₁ and δ ₃ is 180 °, the attitude (folding angle θ and turning angle φ) of the distal end side link hub 2 and the rotary encoder 12 The relational expression between the detected rotation angles β ₁ and β _{3 of} the proximal end link 3 is as follows. The “axial angle γ of the central link 5” means that the connecting end shaft of the central link 5 to which the proximal end link 3 is rotatably connected and the distal end link 4 is rotatably connected. It means the angle formed by the connecting end axis of the central link 5.
cos (θ / 2) sin (β ₁ ) −sin (θ / 2) sin (φ−δ ₁ ) cos (β ₁ ) + sin (γ / 2) = 0 (1)
cos (θ / 2) sin (β ₃ ) −sin (θ / 2) sin (φ−δ ₃ ) cos (β ₃ ) + sin (γ / 2) = 0 (2)

Here, Equation (1) × cos (β ₃ ) + (2) Equation × cos (β ₁ ) is as follows.
cos (θ / 2) {sin (β ₁ ) cos (β ₃ ) + sin (β ₃ ) cos (β ₁ )} − sin (θ / 2) cos (β ₁ ) cos (β ₃ ) {sin (φ− δ ₁ ) + sin (φ−δ ₃ )} + sin (γ / 2) {cos (β ₃ ) + cos (β ₁ )} = 0 (3)

The second term of the equation (3), that is, sin (θ / 2) cos (β ₁ ) cos (β ₃ ) {sin (φ−δ ₁ ) + sin (φ−δ ₃ )} is sin (θ / 2) cos (β ₁ ) cos (β ₃ ) [sin (φ) {cos (δ ₁ ) + cos (δ ₃ )} − cos (φ) {sin (δ ₁ ) + sin (δ ₃ )}] (4)
And can be transformed. Here, since the separation angle δ ₁ of the link mechanism L ₁ is 0 ° and the separation angle δ ₃ of the link mechanism L ₃ is 180 °, if this value is substituted into the equation (4), the equation (4) In the braces, that is, {cos (δ ₁ ) + cos (δ ₃ )} and {sin (δ ₁ ) + sin (δ ₃ )} are both 0, and the second term of equation (3) is 0. Erased.

Therefore, from this equation (3), the bending angle θ of the distal link hub 2 is
θ = 2cos ⁻¹ (A) (5)
By substituting this equation (5) into the aforementioned equation (1), the turning angle φ of the distal end side link hub 2 is
φ = sin ⁻¹ [± {Asin (β ₁ ) + sin (γ / 2)} / {√ (1-A ² ) cos (β ₁ )}] (6)
It becomes. However, A in these formulas (5) and (6) is
A = −sin (γ / 2) [{cos (β ₁ ) + cos (β ₃ )} / {sin (β ₁ ) cos (β ₃ ) + sin (β ₃ ) cos (β ₁ )}] ( 7)
It is.

Based on the simple equations (5) and (6), the posture (fold angle θ and turning angle φ) of the distal end side link hub 2 is uniquely determined from the rotation angles β ₁ and β ₃ of the proximal end link 3. Stipulated in In the above description, the link actuator having three sets of link mechanisms L ₁ to L ₃ has been described, but the same result can be obtained for a link actuator having three or more sets of link mechanisms. That is, if the difference (δ _L −δ _K ) between the separation angles δ _K and δ _L is 180 ° for the K and L th two sets of link mechanisms arbitrarily selected from the three or more sets of link mechanisms. , (5) to (7), β ₁ corresponds to β _K and β ₃ corresponds to β _L , respectively, and the following equations (8) to (10) are obtained.
θ = 2cos ⁻¹ (B) (8)
φ = sin ⁻¹ [± {Bsin (β _K ) + sin (γ / 2)} / {√ (1-B ² ) cos (β _K )}] (9)
B = -sin (γ / 2) [{cos (β K) + cos (β L)} / {sin (β K) cos (β L) + sin (β L) cos (β K)}] ··· ( 10)

As described above, with respect to the two sets of link mechanisms in which the difference in the separation angle of the proximal end link 3 is 180 °, the rotation angle of the proximal end link 3 with respect to the proximal link hub 1 is set to the rotary encoder 12. When the posture of the distal end side link hub 2 is defined by the calculation processing in the control unit 28, complicated calculations such as conventional convergence calculation and case classification are not required. Thus, since complicated calculation is not required, the calculation time can be shortened. Therefore, when the link operating device is applied to a precision medical device, the responsiveness of the link operating device can be improved. Further, since the rotary encoder 12 only needs to be provided in the two sets of link mechanisms, the cost of the link operating device can be reduced and the size can be reduced.

The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

Claims (4)

A proximal end link having one end rotatably connected to the proximal link hub, a distal end link having one end rotatably connected to the distal link hub, and the proximal side The other end of the end link and the other end of the front end side end link are constituted by a central link that is rotatably connected, and has three or more sets of three-joint linkage mechanisms consisting of four rotating pairs. In the link actuating device in which the distal end side link hub is connected to the proximal end side link hub via the link mechanism so that the posture can be changed,
Difference in circumferential separation angle between the base end side end link of one link mechanism and the base end side end link of the other link mechanism for two sets of link mechanisms arbitrarily selected from the above link mechanisms 180 °, and the two sets of link mechanisms are provided with angle detection means for detecting the rotation angle of the proximal end link relative to the proximal link hub, and based on the rotation angle obtained by the angle detection means. A link actuating device comprising arithmetic means for defining the attitude of the distal end side link hub. Connection end shafts of the base end side link hub and the front end side link hub in which one ends of the base end side end link and the front end side end link are rotatably connected, and the base end side end link and the front end side end The link actuating device according to claim 1, wherein an angle formed by a connecting end axis of a central link in which the other end of the link is rotatably connected is 90 °. The link actuating device according to claim 1 or 2, wherein an actuator for arbitrarily changing the attitude of the distal end side link hub is provided in two or more sets of link mechanisms arbitrarily selected from the link mechanisms. The link actuator according to claim 3, wherein the actuator includes an encoder that detects a rotation angle of a proximal end link relative to a proximal link hub.

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