JP6029969B2 - Link actuator - Google Patents

Description

  The present invention relates to a link actuating device used for equipment requiring a precise and wide working range such as medical equipment and industrial equipment.

  An example of a working device having a link mechanism main body is disclosed in Patent Document 1, and an example of a link actuating device used for medical equipment, industrial equipment, and the like is disclosed in Patent Document 2, respectively.

JP 2000-94245 A US Pat. No. 5,893,296

  Since the link mechanism main body of patent document 1 has a small operating angle of each link, in order to set the operating range of a traveling plate large, it is necessary to lengthen a link length. Thereby, there existed a problem that the dimension of the whole mechanism became large and an apparatus became large. Further, when the link length is increased, the rigidity of the entire mechanism is reduced. For this reason, there is a problem that the weight of the tool mounted on the traveling plate, that is, the transportable weight of the traveling plate is limited to a small one. For these reasons, it is difficult to use in a medical device or the like that requires a precise and wide range of operation while having a compact configuration.

  The link actuating device of Patent Document 2 has a configuration in which three or more three-link linkage mechanisms are provided, so that it can operate in a precise and wide range of operation while having a compact configuration. However, since it is difficult to completely eliminate the backlash on the mechanism such as the meshing portion of the gear in the link operating device of this configuration, it is inevitable that the positioning at the time of each operation will be out of order by this backlash. . Further, as the accumulated use time becomes longer, the backlash of the drive mechanism such as a gear is expanded, and the positioning accuracy is also lowered due to the influence.

  The object of the present invention is to enable a high-speed and high-precision positioning operation in a wide operating range while having a compact configuration, and to initially set an origin position as a reference for the positioning operation in any installation situation. It is to provide a link actuating device that can be easily performed.

Link actuator of the present invention, the distal end side link hub relative to the proximal end side of the link hub is changed coupled posture through the three or more sets of link mechanisms, each linkage, each of said proximal end The end link member on the proximal end side and the distal end side that is rotatably connected to the link hub on the side and the distal end side link hub, and both ends on the other end of the end link member on the proximal end side and the distal end side Each of the link mechanisms is connected to a central link member, and a geometric model expressing the link mechanism as a straight line includes a proximal end portion and a distal end side portion with respect to a central portion of the central link member. A link actuating device, wherein the link mechanism is provided with an attitude control actuator that arbitrarily changes the attitude of the distal end side link hub relative to the proximal end side link hub. The attitude control actuator is provided in at least two or more sets in the link mechanism, and is further installed in the base end side link hub so as to be detachable from the front end side link hub. A base positioning member for setting the distal end side link hub to a predetermined posture with respect to the proximal end side link hub in a state of being engaged with the hub, and fixing the proximal end side link hub; An end member and a base for supporting the base end member, and the origin positioning when the distal end side link hub is not set to a predetermined posture with respect to the base end side link hub on the base. A holding means for holding the working member to the base in a fixed position is provided .

  According to this configuration, the link hub on the distal end side moves in two orthogonal directions with respect to the link hub on the proximal end side with the link hub on the proximal end side, the link hub on the distal end side, and three or more sets of link mechanisms. A free two-degree-of-freedom mechanism is configured. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub on the distal end side can be widened. For example, the maximum bend angle between the central axis of the link hub on the proximal end side and the central axis of the link hub on the distal end side is about ± 90 °, and the turning angle of the link hub on the distal end side with respect to the link hub on the proximal end side is 0 ° It can be set in the range of ~ 360 °. By controlling the operation of each posture control actuator, the posture of the distal link hub can be arbitrarily changed with respect to the proximal link hub.

  By setting the distal end side link hub to a predetermined posture with respect to the proximal end side link hub by the origin positioning member, it is possible to determine the origin position as a reference for the operation of each posture control actuator. The origin positioning member is installed on the base end side link hub so as to be able to be engaged with and disengaged from the distal end side link hub. When it is not performed, the engagement with the link hub on the tip side is released. That is, the origin positioning member is always held inside the link actuating device. Therefore, no matter what the installation state of the link actuator is, the base end side of the link actuator is fixed to the gantry or the end effector is attached to the distal end side. Even when the origin positioning member cannot be mounted, the origin positioning can be performed using the origin positioning member held inside.

A proximal member for fixing the link hub before Kimoto end, and a base for supporting the base end member and the base, the distal end side link hub to the proximal end side link hub Holding means for holding the origin positioning member in a fixed position on the base when not set to a predetermined posture is provided .
According to this configuration, the link actuating device is used with the base end side link hub fixed to the base end member and the base end member supported by the base. When the distal end side link hub is not set to the predetermined posture with respect to the proximal end side link hub, the origin positioning member is held on the base by fixing the position. As a result, the origin positioning member and the distal link hub are disengaged, and all or most of the origin positioning member is retracted from the space between the proximal link hub and the distal link hub. Can be made. For this reason, it is possible to prevent the origin positioning member from interfering with other members of the link operating device, and the operating range of the link operating device can be widened. When the origin positioning member is retracted from the space portion, a part of the origin positioning member protrudes from the base end member, but since the base that is a separate member from the base end member is provided, the origin By positioning the protruding portion of the positioning member inside the base, it can be prevented from protruding from the link actuator.

The base may be arranged at a position away from the base end member so that a space is formed between the base end member and the base end member.
If the base is separated from the base member, the protruding portion of the origin positioning member can be positioned not only in the base but also in the space between the base member and the base. The installation space for the positioning member is further increased, and the installation of the origin positioning member is facilitated.

The distance from the base end member to the base is preferably 10 mm to 100 mm, for example.
When the distance from the base end member to the base is set as described above, the origin positioning member is inserted without increasing the overall size of the link actuating device and putting a tool, a hand, etc. in the space between the base end member and the base. Can be operated.

The base end member may be supported by a plurality of support columns installed on the base.
In this case, a wide opening for inserting and removing tools, hands, etc. can be secured in the space between the base end member and the base, and the operation of the origin positioning member is further facilitated. Further, the distance between the base end member and the base can be easily adjusted by changing the length of the column.

The proximal end side link hub, the distal end side link hub, and each of the proximal member, a through hole through which the origin positioning member is inserted may be vignetting set.
By inserting the origin positioning member through each through hole, the distal end side link hub can be easily set to a predetermined posture with respect to the proximal end side link hub.

The center of the through hole of the base end side link hub coincides with the central axis of the base end side link hub, and the through hole of the front end side link hub is the center of the front end side link hub. It should be coincident with the axis.
Since there are no other members near the center portion of the link hub on the proximal end side and the distal end side and there is a relatively large space, a through hole can be provided without interfering with other members. In addition, when the origin positioning member is inserted through the through hole, the origin positioning member is inserted at the center of the entire link operating device, so that the force balance when preload is applied to the link operating device is good.

The holding means may include a male screw portion provided in the origin positioning member and a screw hole provided in the base and into which the male screw portion is screwed. In this case, it is desirable to provide a spanner groove for engaging a spanner for rotating the origin positioning member on the origin positioning member.
If the holding means consists of the male threaded part of the origin positioning member and the screw hole of the base, the origin positioning member can be held and held by rotating the origin positioning member with a tool, hand, etc. Release can be performed easily. Further, when the wrench groove is provided in the origin positioning member, the wrench is engaged with the wrench groove, so that the rotation operation of the origin positioning member is further facilitated and the workability is improved.

In the link actuating device according to the present invention, the posture control actuators are provided in all of the three or more sets of link mechanisms, the position control for controlling the operation amount of each of the posture control actuators, and the torque of each of the posture control actuators may Ru a control device for performing the torque control for controlling.
By controlling the position of each attitude control actuator with the control device in a state where the distal end side link hub is not set to the predetermined attitude with respect to the proximal end side link hub by the origin positioning member, the proximal end The link hub on the distal end side can be changed to an arbitrary posture with respect to the link hub on the side.
In addition, by controlling the torque of each attitude control actuator by the control device in a state where the distal end side link hub is set to a predetermined attitude with respect to the proximal end side link hub by the origin positioning member, A constant preload can be applied to the link mechanism. As a result, the origin position can be recorded in a state in which the rotation acting member such as a gear that transmits the rotation force to the link mechanism is transmitted from the outside of the link actuator or the driving force of the attitude control actuator to each link mechanism. The accuracy of changing the attitude of the link hub on the distal end side with respect to the link hub on the proximal end side is improved.

In the link actuator according to the present invention, the attitude control actuator may include an absolute encoder that detects an operation amount of the attitude control actuator.
By using an absolute encoder, not only the origin position is recorded, but even if the power is turned off and then turned on again, it is not necessary to perform initial setting again, and the origin can be easily returned.

The link actuating device of the present invention is preferably mounted on a linear motion mechanism having one or more axes.
Since the link actuating device of the present invention has the origin positioning member inside the three sets of link mechanisms, even if it is mounted on the stage of a linear motion mechanism such as a single-axis robot, the distal end of the link actuating device with respect to the link hub on the proximal end side The origin positioning operation for setting the link hub on the side to a predetermined posture can be easily performed. By mounting the link actuating device on a linear motion mechanism having one or more axes, positioning in a wider range and positioning in a complicated shape are possible. For example, it is possible to position the protrusion-shaped member from a plurality of directions.

Link actuator of the present invention, the distal end side link hub relative to the proximal end side of the link hub is changed coupled posture through the three or more sets of link mechanisms, each linkage, each of said proximal end The end link member on the proximal end side and the distal end side that is rotatably connected to the link hub on the side and the distal end side link hub, and both ends on the other end of the end link member on the proximal end side and the distal end side Each of the link mechanisms is connected to a central link member, and a geometric model expressing the link mechanism as a straight line includes a proximal end portion and a distal end side portion with respect to a central portion of the central link member. A link actuating device, wherein the link mechanism is provided with an attitude control actuator that arbitrarily changes the attitude of the distal end side link hub relative to the proximal end side link hub. The attitude control actuator is provided in at least two or more sets in the link mechanism, and is further installed in the base end side link hub so as to be detachable from the front end side link hub. A base positioning member for setting the distal end side link hub to a predetermined posture with respect to the proximal end side link hub in a state of being engaged with the hub, and fixing the proximal end side link hub; An end member and a base for supporting the base end member, and the origin positioning when the distal end side link hub is not set to a predetermined posture with respect to the base end side link hub on the base. since the use members comprising a holding means for holding in a position secured to the base, yet compact configuration, it is capable of positioning operation of the high speed and high precision over a wide operating range, in any installation conditions Easily be initialized serving as a reference position of the origin of the positioning operation.

It is the front view which omitted a part of link operating device concerning a 1st embodiment of this invention. It is the front view which abbreviate | omitted a part which shows one state of the link mechanism main body of the link actuating device. It is the front view which abbreviate | omitted one part which shows the different state of the link mechanism main body of the same link actuator. It is the perspective view which represented the link mechanism main body of the link actuating device three-dimensionally. It is the figure which expressed one link mechanism of the link actuating device with a straight line. It is a fragmentary sectional view of the link mechanism main part of the link actuator. It is a partially broken front view which shows the state at the time of the drive of the link actuator. It is a partially broken front view which shows the state at the time of the origin positioning of the link actuator. It is the front view which abbreviate | omitted some link actuating devices concerning 2nd Embodiment of this invention. It is a fragmentary sectional view of the link mechanism main part of the link actuator. It is the elements on larger scale of FIG. It is a partially broken front view which shows the state at the time of the drive of the link actuator. It is a partially broken front view which shows the state at the time of the origin positioning of the link actuator. It is explanatory drawing which shows the state which mounted the link actuator concerning 2nd Embodiment in the uniaxial linear motion mechanism.

An embodiment of the present invention will be described with reference to the drawings.
1 to 8 show a first embodiment of the present invention. As shown in FIG. 1, the link operating device 51 operates the link mechanism main body 1, a support portion 52 that supports the link mechanism main body 1, a tip attachment member 53 to which an end effector 100 is attached, and the link mechanism main body 1. A plurality of attitude control actuators 54 to be controlled, and a control device 55 for controlling these attitude control actuators 54. In this example, the control device 55 is provided in the controller 56, but the control device 55 may be provided separately from the controller 56.

  The link mechanism main body 1 will be described. 2 and 3 are front views showing different states of the link mechanism main body 1. The link mechanism main body 1 has three sets of link mechanisms 4 in which the link hub 3 on the distal end side is linked to the link hub 2 on the proximal end side. It is connected so that the posture can be changed via. 2 and 3, only one set of link mechanisms 4 is shown.

  FIG. 4 is a perspective view showing the link mechanism body 1 three-dimensionally. Each link mechanism 4 includes a base end side end link member 5, a front end side end link member 6, and a central link member 7, and forms a three-joint link mechanism including four rotating pairs. The end link members 5 and 6 on the base end side and the front end side are L-shaped, and the base ends are rotatably connected to the link hub 2 on the base end side and the link hub 3 on the front end side, respectively. The central link member 7 is rotatably connected to the distal ends of the end link members 5 and 6 on the proximal end side and the distal end side at both ends.

  The end link members 5 and 6 on the proximal end side and the distal end side of the three sets of link mechanisms 4 have a structure called a spherical link mechanism, and the respective spherical link centers PA and PB (FIGS. 2 and 3) are The distances from the spherical link centers PA and PB are also the same. The central axis of each rotational pair of the end link members 5 and 6 and the central link member 7 may have a certain crossing angle or may be parallel.

  That is, the three sets of link mechanisms 4 have the same geometric shape. The geometrically identical shape is a geometric model in which the link members 5, 6, and 7 are expressed by straight lines, that is, a model that is expressed by each rotation pair and a straight line connecting these rotation pairs. The base end side part and the front end side part with respect to the center part of the are said to have a symmetrical shape. FIG. 5 is a diagram representing a set of link mechanisms 4 in a straight line.

  The link mechanism 4 of this embodiment is a rotationally symmetric type, and the positions of the proximal-side link hub 2 and the proximal-side end link member 5, the distal-side link hub 3 and the distal-side end link member 6. The relationship is a position configuration that is rotationally symmetric with respect to the center line C of the central link member 7. 2 shows a state where the central axis QA of the link hub 2 on the proximal end side and the central axis QB of the link hub 3 on the distal end side are on the same line, and FIG. 3 shows the central axis of the link hub 2 on the proximal end side. A state in which the central axis QB of the link hub 3 on the distal end side takes a predetermined operating angle with respect to QA is shown. Even if the posture of each link mechanism 4 changes, the distance D between the spherical link centers PA and PB on the proximal end side and the distal end side does not change.

  The link hub 2 on the proximal end side, the link hub 3 on the distal end side, and the three link mechanisms 4 allow the distal link hub 3 to move in the two orthogonal directions relative to the link hub 2 on the proximal end side. A degree mechanism is configured. In other words, it is a mechanism that can freely change the posture of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side with two degrees of freedom of rotation. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side can be widened. For example, the maximum value (maximum folding angle) of the bending angle θ (FIG. 4) between the central axis QA of the proximal end side link hub 2 and the central axis QB of the distal end side link hub 3 can be about ± 90 °. . Further, the turning angle φ (FIG. 4) of the distal end side link hub 3 with respect to the proximal end side link hub 2 can be set in a range of 0 ° to 360 °. The bending angle θ is a vertical angle in which the central axis QB of the distal end side link hub 3 is inclined with respect to the central axis QA of the proximal end side link hub 2, and the turning angle φ is the proximal end side link hub. This is a horizontal angle at which the central axis QB of the link hub 3 on the distal end side is inclined with respect to the central axis QA of the second axis.

  In this link mechanism body 1, the angle and length of the shaft member 13 (FIG. 6) of the end link members 5 and 6 of each link mechanism 4 are equal, and the end link member 5 on the proximal end side and the distal end side link member 5 are on the distal end side. When the geometrical shape of the end link member 6 is equal and the shape of the central link member 7 is the same at the proximal end side, the central link member 7 and the end of the central link member 7 are symmetrical with respect to the symmetry plane of the central link member 7. If the angular positional relationship with the base link members 5 and 6 is the same between the base end side and the tip end side, the base end side link hub 2 and the base end side end link member 5 from the geometric symmetry, The distal end side link hub 3 and the distal end side end link member 6 move in the same manner. For example, when the rotation hubs are provided coaxially with the center axes QA and QB on the link hubs 2 and 3 on the proximal end side and the distal end side, and rotation is transmitted from the proximal end side to the distal end side, the proximal end side and the distal end side are It becomes a constant velocity universal joint that rotates at the same speed at the same rotation angle. The plane of symmetry of the central link member 7 when rotating at a constant speed is referred to as a uniform speed bisector.

  Therefore, by arranging a plurality of link mechanisms 4 having the same geometric shape sharing the base side link hub 2 and the tip side link hub 3 on the circumference, the plurality of link mechanisms 4 can move without contradiction. The central link member 7 is limited to movement only on the equal speed bisector. Thereby, even if the proximal end side and the distal end side have arbitrary operating angles, the proximal end side and the distal end side rotate at a constant speed.

  The link hub 2 on the proximal end side and the link hub 3 on the distal end side each have through-holes 10A and 10B formed in the center thereof along the axial direction, and have a donut shape with a spherical outer shape. The centers of the through-holes 10A and 10B coincide with the center axes QA and QB of the link hubs 2 and 3, and the inner diameter is such that an origin positioning member 106 (FIGS. 7 and 8), which will be described later, is inserted by clearance fitting. It is said that. The through hole 10B of the link hub 10B on the distal end side is not necessarily a through hole as long as the origin positioning member 106 can be engaged. The proximal end link member 5 and the distal end link member 6 rotate at equal intervals in the circumferential direction of the outer peripheral surface of the proximal link hub 2 and distal link hub 3 respectively. It is connected freely.

  FIG. 6 is a cross-sectional view showing a rotating pair portion of the base end side link hub 2 and the base end side end link member 5 and a base end side link member 5 and the central link member 7. is there. In the link hub 2 on the proximal end side, radial shaft holes 11 are formed at three locations in the circumferential direction on the outer peripheral portion, and the shaft members 13 are rotatably supported by two bearings 12 provided in each shaft hole 11. Has been. The outer end of the shaft member 13 protrudes from the link hub 2 on the base end side, and the end link member 5 on the base end side is coupled to the protruding screw portion 13 a and is fastened and fixed by a nut 14.

  The bearing 12 is a rolling bearing such as a deep groove ball bearing, for example, and an outer ring (not shown) is fitted to the inner circumference of the shaft hole 11, and an inner ring (not shown) is the outer circumference of the shaft member 13. Is fitted. The outer ring is retained by a retaining ring 15. Further, a spacer 16 is interposed between the inner ring and the end link member 5 on the base end side, and the tightening force of the nut 14 is transmitted to the inner ring via the end link member 5 and the spacer 16 on the base end side. Thus, a predetermined preload is applied to the bearing 12.

  The rotating pair of the end link member 5 and the center link member 7 on the base end side is provided with two bearings 19 in communication holes 18 formed at both ends of the center link member 7. The shaft portion 20 at the tip of the end link member 5 is rotatably supported. The bearing 19 is fastened and fixed by a nut 22 via a spacer 21.

  The bearing 19 is a rolling bearing such as a deep groove ball bearing, for example, and an outer ring (not shown) is fitted to the inner circumference of the communication hole 18, and an inner ring (not shown) is the outer circumference of the shaft portion 20. Is fitted. The outer ring is retained by a retaining ring 23. A tightening force of the nut 22 screwed to the tip screw portion 20a of the shaft portion 20 is transmitted to the inner ring through the spacer 21 to apply a predetermined preload to the bearing 19.

  As described above, the rotation pair of the proximal link hub 2 and the proximal link member 5 and the rotation link of the proximal link member 5 and the central link member 7 have been described. The rotation pair of the link hub 3 and the end link member 6 on the front end side and the rotation pair of the end link member 6 and the center link member 7 on the front end side have the same configuration (not shown).

  As described above, the four rotation pairs of each link mechanism 4, that is, the rotation pairs of the proximal end side link hub 2 and the proximal end link member 5, the distal link hub 3 and the distal end Bearings 12 are provided on the rotating pair of the link member 6, the end link member 5 and the central link member 7 on the base end side, and the rotating pair of the link member 6 on the proximal end. , 19 can be used to reduce the frictional resistance by reducing the frictional resistance at each rotational pair, so that smooth power transmission can be ensured and the durability can be improved.

  In the structure in which the bearings 12 and 19 are provided, by applying a preload to the bearings 12 and 19, the radial gap and the thrust gap can be eliminated, and shakiness of the rotation pair can be suppressed. The rotational phase difference between the link hub 3 side on the side and the distal end side is eliminated, and the constant velocity can be maintained and the occurrence of vibration and abnormal noise can be suppressed. In particular, by setting the bearing clearance between the bearings 12 and 19 to be a negative clearance, backlash generated between input and output can be reduced.

  By providing the bearing 12 embedded in the link hub 2 on the proximal end side and the link hub 3 on the distal end side, the outer shape of the entire link mechanism body 1 is not increased, and the link hub 2 on the proximal end side and the distal end side link hub 2 are The outer shape of the link hub 3 can be enlarged. Therefore, it is easy to secure a mounting space for mounting the proximal-side link hub 2 and the distal-side link hub 3 to other members.

In FIG. 1, the support 52 includes a base 102 fixed to the base 101 with bolts or the like (not shown), a plurality of pillars 103 installed on the upper surface of the base 102, and these pillars. 103 and a base end member 104 supported on the upper end of the base end member 104.
The link hub 2 on the base end side of the link mechanism main body 1 is fixed with a bolt or the like (not shown) through the spacer 105. The plurality of posture control actuators 54 are attached to the base end member 104 in a suspended state at equal intervals in the circumferential direction. The number of posture control actuators 54 is three, which is the same as the number of link mechanisms 4. The number of attitude control actuators 54 may be two. The posture of the distal end side link hub 3 with respect to the proximal end side link hub 2 is determined by two posture control actuators 54, but three are required when preload is applied to the link mechanism body 1 by torque control described later.

  The attitude control actuator 54 is a rotary actuator, and a bevel gear 57 attached to its output shaft and a fan-shaped bevel gear 58 attached to the shaft member 13 (FIG. 6) of the link hub 2 on the proximal end side mesh with each other. The attitude control actuator 54 is provided with an absolute encoder 59 that detects the operation amount of the attitude control actuator 54.

  7 and 8 are partially cutaway front views showing different states of the link actuator 51. FIG. As shown in the figure, a screw hole 102a is provided at the center of the base 102 along the vertical direction. In addition, through holes 104 a and 105 a penetrating vertically are provided in the center of the base end member 104 and the spacer 105. The screw hole 102a and the through holes 104a and 105a have the same axial center position as the through hole 10A of the link hub 2 on the proximal end side. The through holes 104a and 105a have the same diameter as the through holes 10A and 10B of the link hubs 2 and 3 on the proximal end side and the distal end side.

  A circular rod-like origin positioning member 106 is inserted into each of the through holes 10A, 10B, 104a, and 105a with a clearance fit. The origin positioning member 106 has a male screw portion 106 a that can be screwed into the screw hole 102 a of the base 102 at the lower end. When the screw hub 102a of the base 102 and the male screw portion 106a of the origin positioning member 106 do not set the distal end side link hub 3 to a predetermined posture with respect to the proximal end side link hub 2, the origin positioning member 106 The holding means 107 is configured to hold the base plate 102 in a fixed position. Further, a spanner groove 106b capable of engaging with a spanner is formed at the center in the length direction of the origin positioning member 106.

  FIG. 7 shows a state when the link mechanism body 1 is operated. At this time, in the origin positioning member 106, the male screw portion 106a is screwed into the screw hole 102a of the base 102, and the through holes 104a and 105a of the base end member 104, the spacer 105, and the link hub 2 on the base end side. , 10A, but not inserted into the through hole 10B of the link hub 3 on the distal end side. That is, the origin positioning member 106 and the distal end side link hub 3 are disengaged. In this state, when each attitude control actuator 54 is rotationally driven, the rotation is transmitted to the shaft member 13 (FIG. 6) via a pair of bevel gears 57 and 58, and the proximal end with respect to the link hub 2 on the proximal end side. The angle of the side end link member 5 is changed. Thereby, the posture of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end side (hereinafter referred to as “tip posture”) is determined.

  The posture control for controlling the tip posture may be performed manually by an operating tool (not shown) provided in the controller 56 (FIG. 1), or determined by a setting device (not shown) provided in the controller 56. Alternatively, automatic control may be performed by the control device 55 (FIG. 1) so as to obtain the set amount. The control device 55 is of a numerical control type by a computer, and performs position control for controlling the operation amount of each attitude control actuator 54 and torque control for controlling the torque of each attitude control actuator 54.

When performing the automatic control, the control target value of the rotation angle βn of the proximal end side end link member 5 is calculated according to the distal end posture set by the setting device. The calculation of the rotation angle βn is performed by inversely transforming Equation 1 below. Inverse conversion refers to the bending angle θ (FIG. 4) between the center axis QA of the link hub 2 on the proximal end side and the center axis QB of the link hub 3 on the distal end side, and the link hub on the output side with respect to the link hub 2 on the proximal end side. 3 is a conversion for calculating the rotation angle βn of the end link member 5 on the base end side from the swivel angle φ (FIG. 4).
cos (θ / 2) sinβn−sin (θ / 2) sin (φ + δn) cosβn + sin (γ / 2) = 0
... (Formula 1)
Here, γ (FIG. 4) is rotatably connected to the connecting end shaft of the central link member 7 rotatably connected to the end link member 5 on the base end side and the end link member 6 on the tip end side. The angle formed by the connecting end axis of the central link member 7. δn (δ1, δ2, δ3 in FIG. 4) is a circumferential separation angle of each base end side end link member 5 with respect to the base end side end link member 5 serving as a reference.

  When the control target value of the rotation angle βn is calculated, the position control of each attitude control actuator 54 is feedback controlled using the signal of the encoder 59 (FIG. 1) so that the rotation angle βn becomes the control target value. To do. The bending angle θ, the turning angle φ, and the rotation angle βn are mutually related, and the other value can be derived from one value. Thus, the tip posture is determined by controlling the position of each posture control actuator 54.

  In the case of this link actuating device 51, it is difficult to completely eliminate the backlash on the mechanism at the meshing portions of the pair of bevel gears 57 and 58, for example. Further, as the accumulated use time becomes longer, the backlash of the bevel gears 57, 58 and the like is expanded, and the play is increased. If the position control of the posture control actuator 54 is performed ignoring the presence of the play, the tip posture is deviated by the amount of play. Therefore, in order to eliminate the deviation of the tip posture, the origin positioning which is the reference for the operation of the posture control actuator 54 is performed according to the size of the play.

FIG. 8 shows a state at the time of origin positioning. That is, from the state of FIG. 7, the male threaded portion 106a of the origin positioning member 106 and the screw hole 102a of the base 102 are unscrewed, the origin positioning member 106 is moved upward, and its upper end is linked to the distal end side link. It passes through the through hole 10 </ b> B of the hub 3. In other words, the origin positioning member 106 is engaged with the link hub 3 on the distal end side. The turning operation of the origin positioning member 106 for removing the male screw portion 106a from the screw hole 102a is performed by putting a hand in the space 108 between the base 102 and the base end member 104, for example. Even when the space 108 is narrow and a hand cannot be reached, by engaging a spanner (not shown) with the spanner groove 106b, the origin positioning member 106 can be easily rotated.
For example, if the distance H (FIG. 1) from the base end member 104 to the base 102 is in the range of 10 mm to 100 mm, the base end member 104 and the base 102 are not increased without increasing the overall size of the link actuating device 51. It is possible to operate the origin positioning member 106 by putting a tool, a hand, or the like in the space 108 between them.

In the state of FIG. 8, preload is applied to the link mechanism main body 1 by performing torque control that applies a certain amount of torque to each attitude control actuator 54 in a certain direction by the control of the control device 55 (FIG. 1). be able to. As a result, it is possible to loosen the gears 57 and 58 that are rotation transmission members that transmit rotation from the respective rotation pairs of the link mechanism body 1 and the attitude control actuator 54 to each link mechanism 4. The position of the encoder 59 (FIG. 1) of each attitude control actuator 54 at this time is stored as the origin position. Thereafter, by controlling the position of each attitude control actuator 54 with reference to the stored origin position, it is possible to change the tip attitude with high precision in a loosely packed state.
Since the absolute encoder 59 is provided as a means for detecting the operation amount of the attitude control actuator 54, not only the origin position is recorded, but even when the power is turned off and turned on again, there is no need to perform initial setting again. It is possible to return to the origin easily.

  When the distal end side link hub 3 is not set to a predetermined posture with respect to the proximal end side link hub 2 (FIG. 7), and when the distal end side link hub 3 is determined relative to the proximal end side link hub 2. In any case (FIG. 8), the origin positioning member 106 is provided inside the link actuator 51. As in this embodiment, when the distal end mounting member 53 and the end effector 100 are mounted on the link hub 3 on the distal end side, and the base 102 is fixed to the gantry 101, the origin positioning member 106 is moved from the outside to the distal end side. The through-holes 10B, 10A, 105a, 104a of the link hub 3, the base end side link hub 2, the spacer 105, and the base end member 104 cannot be inserted. However, as long as the origin positioning member 106 is provided in the link actuator 51 as described above, the origin positioning can be performed using the origin positioning member 106 in any situation.

  In this embodiment, the center of each of the through holes 10A, 105a, 104a of the link hub 2, the spacer 105, and the base end member 104 on the base end side coincides with the center axis QA of the link hub 2 on the base end side, and the tip The center of the through-hole 10B of the link hub 3 on the side coincides with the center axis QB of the link hub 3 on the distal end side. The central portions of the link hubs 2 and 3 on the proximal end side and the distal end side do not have other members nearby and have a relatively large space, so that the through holes 10A and 10B are provided without interfering with other members. be able to. Further, when the origin positioning member 106 is inserted into the through holes 10A and 10B, the origin positioning member 106 is inserted into the center of the link mechanism body 1, so that when the preload is applied to the link mechanism body 1. Good balance of power.

  Since the base 102 is disposed at a position separated from the base end member 104 so that a space 108 is formed between the base end member 104 and the base end member 104, the base side link hub 2 has a distal end side link. When the hub 3 is not set to the predetermined posture, the installation space for the origin positioning member 106 is widened, and the origin positioning member 106 is easily installed. In addition, the origin positioning member 106 can be installed without protruding into the space between the proximal end side link hub 2 and the distal end side link hub 3, and the origin positioning member 106 interferes with other members. You can avoid doing it. Thereby, the operating range of the link mechanism main body 1 can be widened. In FIG. 8, the upper end of the origin positioning member 106 protrudes slightly upward from the proximal-side link hub 2, but this protruding portion does not interfere with other members of the link mechanism main body 1. It does not interfere with the operation of the main body 1.

  Further, as in this embodiment, when the base end member 104 is supported by a plurality of support columns 103 installed on the base 102, a tool, a hand, or the like is placed in the space 108 between the base end member 104 and the base 102. A wide opening for taking in and out can be secured, and the operation of the origin positioning member 106 becomes even easier. Further, when the base end member 104 is supported by the support column 103, the distance between the base end member 104 and the base 102 can be easily adjusted by changing the length of the support column 103.

  9 to 13 show a second embodiment of the present invention. As shown in FIG. 9, the link actuating device 51 also has a link mechanism main body 1, a support portion 52 that supports the link mechanism main body 1, and a tip attachment for attaching the end effector 100, as in the first embodiment. A member 53, a plurality of posture control actuators 54 for operating the link mechanism body 1, and a control device 55 for controlling the posture control actuators 54 are provided.

  Further, the support portion 52 includes a base 102 fixed to the base 101 with bolts or the like (not shown), a plurality of support columns 103 installed on the base 102, and upper ends of the support columns 103. The base end member 104 is supported, and the base end side link hub 2 of the link mechanism main body 1 is fixed to the base end member 104 via a spacer 105 with a bolt or the like (not shown). The plurality of posture control actuators 54 are attached to the base end member 104 in a suspended state at equal intervals in the circumferential direction. The number of posture control actuators 54 is three, which is the same as the number of link mechanisms 4. Similar to the first embodiment, the number of attitude control actuators 54 may be two.

  As shown in FIGS. 12 and 13, the link hubs 2 and 3 on the proximal end side and the distal end side of the link mechanism main body 1 have through holes 10 </ b> A and 10 </ b> B formed in the center portion along the axial direction. The centers of the through-holes 10A and 10B coincide with the center axes QA and QB of the link hubs 2 and 3, and the inner diameters of the through-holes 10A and 10B are dimensioned so that the origin positioning member 106 is inserted by clearance fitting.

  As shown in FIG. 11, the link mechanism main body 1 has a bearing 31 for rotatably supporting the end link members 5 and 6 with respect to the link hub 2 on the proximal end side and the link hub 3 on the distal end side. It is what. The rotation pair of the base end side link hub 2 and the base end side end link member 5 will be described as an example. The shaft portions 32 are formed at three locations in the circumferential direction of the base end side link hub 2. Inner rings (not shown) of the two bearings 31 are fitted to the outer periphery of the shaft portion 32, and an outer ring (not shown) of the bearing 31 is fitted to the inner periphery of the communication hole 33 formed in the end link member 5 on the proximal end side. ) Is fitted. The bearing 31 is a ball bearing such as a deep groove ball bearing or an angular ball bearing, for example, and is fixed in a state where a predetermined preload is applied by tightening with a nut 34. The rotating pair of the distal end side link hub 3 and the distal end side end link member 6 also has the same structure as described above.

  Further, the bearing 36 provided at the rotating pair of the end link member 5 and the central link member 7 on the base end side is formed on the inner periphery of the communication hole 37 formed at the tip of the end link member 5 on the base end side. An outer ring (not shown) is fitted, and an inner ring (not shown) is fitted to the outer periphery of the shaft portion 38 integrated with the central link member 7. The bearing 36 is, for example, a ball bearing such as a deep groove ball bearing or an angular ball bearing, and is fixed in a state where a predetermined preload is applied by tightening with a nut 39. The rotating pair of the end link member 6 and the center link member 7 on the front end side has the same structure as described above.

  As shown in FIGS. 10 and 11, the posture control actuator that arbitrarily changes the tip posture by rotating the end link member 5 on the base end side in all of the three sets of link mechanisms 4 of the link mechanism body 1. 54, and a speed reduction mechanism 71 that transmits the operation amount of the attitude control actuator 54 to the base end side end link member 5 at a reduced speed. The attitude control actuator 54 is a rotary actuator, more specifically, a servomotor with a speed reducer 54 a, and is fixed to the base end member 104 by a motor fixing member 72. The speed reduction mechanism 71 includes a speed reducer 54 a of the attitude control actuator 54 and a gear type speed reduction unit 73.

  The gear-type reduction unit 73 is fixed to the small gear 76 connected to the output shaft 54b of the attitude control actuator 54 via a coupling 75 so as to be able to transmit rotation, and to the end link member 5 on the base end side and fixed to the small gear 73. A large gear 77 that meshes with the gear 76 is formed. In the illustrated example, the small gear 76 and the large gear 77 are spur gears, and the large gear 77 is a sector gear in which teeth are formed only on a sector-shaped peripheral surface. The large gear 77 has a larger pitch circle radius than the small gear 76, and the rotation of the output shaft 54 b of the attitude control actuator 54 moves to the proximal end side link member 5, and the proximal end side link hub 2 and the proximal end side link member 5. The rotation is reduced and transmitted to the rotation around the rotation axis O <b> 1 of the rotation pair with the end link member 5. The reduction ratio is 10 or more.

  The pitch circle radius of the large gear 77 is set to ½ or more of the arm length L of the end link member 5 on the base end side. The arm length L is determined from the axial center point P1 of the central axis O1 of the rotational pair of the base end side link hub 2 and the base end side end link member 5 to the base end side end link member 5 and the center. An axial center point P1 of the axial center point P2 of the center axis O2 of the rotational pair with the link member 7 is orthogonal to the rotational pair axis O1 of the base end side link hub 2 and the base end side end link member 5. The distance to the point P3 projected on the plane passing through. In the case of this embodiment, the pitch circle radius of the large gear 77 is not less than the arm length L. Therefore, it is advantageous to obtain a high reduction ratio.

  The small gear 76 has shaft portions 76 b protruding on both sides of a tooth portion 76 a meshing with the large gear 77, and both the shaft portions 76 b are provided on two rotation support members 79 installed on the base end member 104. The bearings 80 are rotatably supported. The bearing 80 is a ball bearing such as a deep groove ball bearing or an angular ball bearing. In addition to arranging ball bearings in double rows as in the illustrated example, roller bearings or sliding bearings may be used. A shim (not shown) is provided between the outer rings (not shown) of the two bearings 80, and a preload is applied to the bearing 80 by tightening a nut 81 screwed into the shaft portion 76b. The outer ring of the bearing 80 is press-fitted into the rotation support member 79.

  In the case of this embodiment, the large gear 77 is a member separate from the end link member 5 on the base end side, and is detachably attached to the end link member 5 on the base end side by a coupler 82 such as a bolt. ing. The large gear 77 may be integrated with the end link member 5 on the base end side.

  The rotation axis O3 of the attitude control actuator 54 and the rotation axis O4 of the small gear 76 are located on the same axis. These rotational axes O3 and O4 are parallel to the rotation pair axis O1 of the base end side link hub 2 and the base end side end link member 5 and have the same height from the base end member 104. .

  As shown in FIG. 9, the link actuating device 51 is also controlled by the control device 55 based on the detection signal of the absolute encoder 59 that detects the operation amount of the attitude control actuator 54, as in the first embodiment. The position of each attitude control actuator 54 is controlled to change the attitude of the link hub 3 on the distal end side relative to the link hub 2 on the proximal end side. At this time, as shown in FIG. 12, the male screw portion 106 a of the origin positioning member 106 is screwed into the screw hole 102 a of the base 102. Thus, the origin positioning member 106 is inserted into the base end member 104, the spacer 105, and the through holes 104a, 105a, and 10A of the base end side link hub 2, but the front end side link hub 3 has a through hole. 10B is not inserted. Since the control method by the control device 55 is the same as described above, the description thereof is omitted.

  Further, similarly to the first embodiment, in order to eliminate the deviation of the tip posture due to the backlash on the mechanism by the gear type reduction unit 73 or the like, each of the posture control actuators 54 is torque-controlled by the control device 55. The origin position that is the reference for the operation of each attitude control actuator 54 is initially set. At this time, using the origin positioning member 106, the male screw portion 106a of the origin positioning member 106 and the screw hole 102a of the base 102 are removed from the state shown in FIG. The member 106 is moved upward, and its upper end is inserted into the through hole 10B of the link hub 3 on the distal end side. The origin positioning method is as described above.

  In this link actuating device 51, the attitude control actuator 54 and the speed reduction mechanism 71 are provided in all of the three sets of link mechanisms 4, so that the distal end side link hub 3 can be operated with respect to the proximal end side link hub 2. Can be driven in a well-balanced manner even when taking a proper posture. That is, the driving force balance is good. Thereby, each attitude control actuator 54 can be reduced in size. Further, by providing the posture control actuator 54 and the speed reduction mechanism 71 in all of the three sets of link mechanisms 4, it is possible to control the back of the link mechanism main body 1 and the speed reduction mechanism 71 so that the link on the tip side is reduced. The positioning accuracy of the hub 3 can be improved, and the rigidity of the link actuator 51 itself can be increased.

  The gear type reduction unit 73 of the reduction mechanism 71 is a combination of a small gear 76 and a large gear 77, and a high reduction ratio of 10 or more can be obtained. If the reduction ratio is high, the positioning resolution by the encoder 59 and the like is increased, so that the positioning resolution of the link hub 3 on the distal end side is improved. Further, a low output attitude control actuator 54 can be used. In this embodiment, the attitude control actuator 54 with the speed reducer 54a is used. However, if the reduction ratio of the gear-type speed reducer 73 is high, the attitude control actuator 54 without the speed reducer can be used. The attitude control actuator 54 can be downsized.

By setting the pitch circle radius of the large gear 77 to ½ or more of the arm length L of the end link member 5 on the base end side, the bending moment of the end link member 5 on the base end side due to the tip load is reduced. . Therefore, it is not necessary to increase the rigidity of the entire link actuator 51 more than necessary, and the weight of the end link member 5 on the base end side can be reduced. For example, the end link member 5 on the base end side can be changed from stainless steel (SUS) to aluminum. Further, since the pitch circle radius of the large gear 77 is relatively large, the surface pressure of the tooth portion of the large gear 77 is reduced, and the rigidity of the entire link actuator 51 is increased.
Further, when the pitch circle radius of the large gear 77 is equal to or greater than ½ of the arm length, the large gear 77 is installed at the rotating pair of the base end side link hub 2 and the base end side end link member 5. Since the diameter of the bearing 12 is sufficiently larger than the outer diameter of the bearing 12, a space is created between the toothed portion of the large gear 77 and the bearing 12, and the large gear 77 can be easily installed.

  In particular, in the case of this embodiment, the pitch circle radius of the large gear 77 is equal to or greater than the arm length L. Therefore, the pitch circle radius of the large gear 77 is further increased, and the above-described action and effect appear more remarkably. In addition, the small gear 76 can be installed on the outer diameter side of the link mechanism 4. As a result, an installation space for the small gear 76 can be easily secured, and the degree of freedom in design increases. Further, interference between the small gear 76 and other members is less likely to occur, and the movable range of the link actuator 51 is widened.

  Since the small gear 76 and the large gear 77 are spur gears, they are easy to manufacture and have high rotation transmission efficiency. Since the small gear 76 is supported by the bearings 80 on both sides in the axial direction, the support rigidity of the small gear 76 is high. As a result, the angle holding rigidity of the end link member 5 on the base end side due to the distal end load is increased, leading to improvement in the rigidity and positioning accuracy of the link actuator 51. Further, the rotation axis O3 of the attitude control actuator 54, the rotation axis O4 of the small gear 76, and the central axis O1 of the rotation pair of the base end side link hub 2 and the base end side end link member 5 are the same. Since it is on a flat surface, the overall balance is good and the assemblability is good.

  Since the large gear 77 is detachable with respect to the end link member 5 on the base end side, the reduction ratio of the gear-type reduction portion 73 and the operation of the link hub 3 on the front end side with respect to the link hub 2 on the base end side. It becomes easy to change the specifications such as the range, and the mass productivity of the link actuator 51 is improved. That is, the same link actuator 51 can be applied to various uses by simply changing the large gear 77. Also, maintainability is good. For example, when a failure occurs in the gear-type reduction unit 73, it is possible to deal with it by replacing only the reduction unit 73.

  FIG. 14 shows an example in which the link operating device shown in FIGS. 9 to 13 is mounted on a single-axis robot that is a single-axis linear motion mechanism. In this case, since the single-axis robot 110 is installed on the gantry 101 and the base 102 is mounted on the moving stage 111 of the single-axis robot 110, the origin positioning member 106 is moved from the base 102 side to each through hole of the link actuator 51. 10A, 10B, 104a, 105a (FIGS. 12 and 13) cannot be inserted. Further, since the end effector 100 is attached to the link hub 3 on the distal end side via the distal end attachment member 53, the origin positioning member 106 is inserted into the through holes 10A, 10B, 104a, 105a unless the end effector 100 is removed. Cannot be inserted. However, if the origin positioning member 106 is provided inside the link actuator 51 as in the link actuator 51, the origin can be easily positioned in any installation situation.

  When the link actuator 51 is mounted on the single-axis robot 110 that is a single-axis linear motion mechanism as in this example, the work plane 112 is controlled by controlling the position of the single-axis robot 110 and the attitude of the link actuator 51. Irradiation with laser light, visible light, etc., application of an adhesive, grease, etc., inspection with a camera or the like can be performed on both side surfaces of the protruding portion 113 provided above. If the link actuating device 51 is mounted on a moving stage (not shown) driven by a biaxial linear motion mechanism, it is possible to work on all the side surfaces of the protrusion 113. That is, by mounting the link operating device 51 on a linear motion mechanism having one or more axes, positioning in a wider range and positioning in a complicated shape are possible.

DESCRIPTION OF SYMBOLS 1 ... Link mechanism main body 2 ... Base end side link hub 3 ... Front end side link hub 4 ... Link mechanism 5 ... Base end side end link member 6 ... Front end side end link member 7 ... Central link member 10A, 10B, 104a, 105a ... through-hole 51 ... link actuator 54 ... attitude control actuator 55 ... control device 59 ... absolute encoder 102 ... base 102a ... screw hole 103 ... post 104 ... proximal member 106 ... origin positioning member 106a ... male screw part 106b ... spanner groove 107 ... holding means 108 ... space 110 ... single-axis robot (linear motion mechanism)
QA: Center axis of the base end side link hub QB: Center axis of the end side link hub

Claims (8)

The distal end side link hub to link hub of the base end side, is changed coupled posture through the three or more sets of link mechanisms, each linkage, respectively link hub and the distal end of the proximal-side End link members on the base end side and the tip end side, one end of which is rotatably connected to the link hub, and a center on which both ends are rotatably connected to the other ends of the end link members on the base end side and the tip end side, respectively. Each of the link mechanisms is a geometric model in which the link mechanism is represented by a straight line, and the base end side portion and the tip end side portion are symmetrical with respect to the center portion of the center link member, In the link actuating device provided with an attitude control actuator for arbitrarily changing the attitude of the distal end side link hub with respect to the proximal end side link hub in the link mechanism,
At least two sets of the attitude control actuators are provided in the link mechanism,
Further, the base end side link hub is detachably attached to the front end side link hub, and is engaged with the front end side link hub in the state where the base end side link hub is engaged with the base end side link hub. An origin positioning member for setting the distal end side link hub in a predetermined posture, a proximal end member for fixing the proximal end side link hub, and a base for supporting the proximal end member; And holding means for holding the origin positioning member fixedly on the base when the distal end side link hub is not set to a predetermined posture with respect to the proximal end side link hub. Link actuating device. The link actuator according to claim 1 , wherein the base is disposed at a position separated from the base end member so that a space is formed between the base end member and the base end member. 3. The link operating device according to claim 1 , wherein the origin positioning member is inserted into each of the proximal end side link hub, the distal end side link hub, and the proximal end member. There link actuating device that has been kicked set. 4. The link actuating device according to claim 3 , wherein a center of the through hole of the base end side link hub coincides with a center axis of the base end side link hub and the through end of the front end side link hub is formed. A link actuating device in which the hole coincides with the central axis of the link hub on the distal end side. The link actuating device according to any one of claims 1 to 4 , wherein the holding means is engaged with a male screw portion provided on the origin positioning member and a male screw portion provided on the base. A link actuator consisting of screw holes. In link actuator according to any one of claims 1 to 5, provided with the attitude control actuator for all of the three or more sets of link mechanisms, controls the operation of each of the attitude control actuator position control and the link actuator having a control device for performing the torque control for controlling the torque of the attitude control actuator. The link actuator according to any one of claims 1 to 6 , wherein the attitude control actuator includes an absolute encoder that detects an operation amount of the attitude control actuator. The link actuating device according to any one of claims 1 to 7 , which is mounted on a linear motion mechanism having one or more axes.

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