阅读说明：本技术 连杆促动装置 (Connecting rod actuating device ) 是由 野濑贤藏 矶部浩 于 2019-09-24 设计创作，主要内容包括：连杆促动装置包括：平行连杆机构(10),该平行连杆机构(10)将前端侧的连杆枢毂(13)经由三组以上的连杆机构(14)以可改变姿势的方式与基端侧的连杆枢毂(12)连接；姿势控制用驱动源(11)；控制装置(2)。控制装置(2)具有异常检测机构(4),该异常检测机构(4)具有：测定部(5),该测定部(5)测量：受平行连杆机构(10)及其姿势控制用驱动源(11)所构成的连杆促动装置本体(1)中的旋转对偶部的异常影响的确定状态值；判定部(6),该判定部(6)根据该测定部(5)的测定结果而判定旋转对偶部的任一个中存在异常。测定部(5)比如测定刚性或驱动转矩。(The link actuating device includes: a parallel link mechanism (10) which connects the link hub (13) on the distal end side to the link hub (12) on the proximal end side via three or more sets of link mechanisms (14) so as to be capable of changing the posture of the link hub; a drive source (11) for controlling the posture; a control device (2). The control device (2) is provided with an abnormality detection mechanism (4), and the abnormality detection mechanism (4) is provided with: a measurement unit (5), wherein the measurement unit (5) measures: a determination state value that is affected by an abnormality of a rotation pair part in a link actuator main body (1) that is composed of a parallel link mechanism (10) and a drive source (11) for controlling the attitude thereof; and a determination unit (6), wherein the determination unit (6) determines that there is an abnormality in any one of the pair of rotating units on the basis of the measurement result of the measurement unit (5). The measuring unit (5) measures, for example, rigidity or drive torque.)

1. A link actuator device, comprising: a parallel link mechanism that connects the link hub on the distal end side to the link hub on the base end side via a link mechanism so as to be capable of changing a posture, and that has a rotation dual section as a portion where the link mechanism is connected; an attitude control drive source that arbitrarily changes an attitude of the link hub on a tip side with respect to the link mechanism; a control device for controlling the attitude control drive source, the control device comprising:

a measurement unit that measures a specific state value affected by an abnormality of the rotating pair portion, the rotating pair portion being located in a link actuator main body, the link actuator main body being configured by the parallel link mechanism and the attitude control drive source; and a determination unit that determines, based on a measurement result of the measurement unit, that there is an abnormality in any one of the rotation pair units in the link actuator main body.

2. The link actuator according to claim 1, wherein the measuring portion measures rigidity of the link actuator main body, and the determining portion determines the abnormality according to a rule determined by the measurement value of the measuring portion.

3. The link actuator according to claim 2, wherein the measuring unit measures a natural frequency of the link actuator body and estimates the rigidity from the natural frequency.

4. The link actuator according to claim 2, wherein the measuring unit measures a torque of the attitude control drive source, and the rigidity of the link actuator body is estimated based on the measured torque.

5. The link actuator according to any one of claims 1 to 4, wherein the determination unit has a storage unit that stores the state values in a plurality of postures of the link actuator main body when the respective rotating pairs of the link actuator main body are normal, and the determination unit compares the stored state values in the plurality of postures with the state value measured by the measurement unit to determine the abnormality.

6. The link actuator according to any one of claims 1 to 4, wherein the control device is provided with an abnormality determination operation command unit that drives the posture control drive source so that the link actuator main body assumes a predetermined posture for abnormality determination.

Technical Field

The present invention relates to a link actuator used for an instrument requiring a precise and large actuation range, such as a medical instrument or an industrial instrument, and particularly relates to a technique for determining an abnormality of a rotation dual part thereof.

Background

As a link actuator having a compact structure and capable of performing precise and wide-range actuation, for example, devices shown in patent documents 1 to 4 have been proposed. The link actuator of patent document 1 includes: a parallel link mechanism which connects the link hub on the front end side to the link hub on the base end side via three or more sets of link mechanisms so as to be capable of changing the posture; and a posture control drive source that arbitrarily changes the posture of the distal-end-side link hub with respect to the proximal-end-side link hub by two or more link mechanisms among the three or more link mechanisms.

Documents of the prior art

Patent document

Patent document 1: JP Kokai No. 2000-094245

Patent document 2: US5893296 patent document

Patent document 3: JP 4476603A

Patent document 4: JP 5785055A

Disclosure of Invention

Problems to be solved by the invention

In the above-described configuration of the link actuator, when assembling, a spacer is interposed between the bearings provided in the respective rotating pair portions to apply a preload, so that the clearance between the rotating pair portions is eliminated, thereby improving positioning accuracy and rigidity. Further, by combining the bearings (front surface alignment (DB), back surface alignment (DF), etc.), the rigidity of the rotation dual part can be improved, and the positioning accuracy and rigidity of the device can be improved. However, when such a rotating pair part is assembled, the desired positioning accuracy and rigidity may not be obtained due to forgetting to insert/overlap the spacer, an error in assembling the bearings, and the like. In addition, it is sometimes difficult to detect a decrease in positioning accuracy or rigidity due to wear accompanying long-term operation at an initial stage.

Further, in the parallel link mechanism having the configuration of patent document 3, since the rigidity of the link portion changes depending on the posture of the front end member, it is difficult to detect a failure at the time of assembly, a decrease in rigidity such as abrasion due to long-term continuous operation, and a cause of a decrease in positioning accuracy. Therefore, in the parallel link mechanism having the above-described configuration, it is desirable to easily detect an abnormality during inspection or continuous operation at the time of shipment.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a link actuator device that can easily detect a reduction in rigidity and positioning accuracy caused by an assembly error of a link actuator device body or a long-term operation without being disassembled and even when the operation is continued.

Means for solving the problems

The link actuator according to the present invention will be described with reference to the drawings. The link actuating device of the present invention comprises: a parallel link mechanism 10 which connects a link hub 13 on the distal end side to a link hub 12 on the proximal end side via a link mechanism 14 so as to be capable of changing the posture, and which has a pair of rotating parts 31 to 34 as a part for connecting the link mechanism 14; attitude control drive sources 11(11-1 to 11-3) for arbitrarily changing the attitude of the link hub 13 on the tip side with respect to the link mechanism 14; a control device 2 that controls the attitude control drive source 11;

the control device 2 includes:

a measuring unit 5 for measuring a specific state value affected by an abnormality of the rotating pair units 31 to 34, the rotating pair units 31 to 34 being located in a link actuator main body 1, the link actuator main body 1 being constituted by the parallel link mechanism 10 and the attitude control drive source 11; and a determination unit 6, wherein the determination unit 6 determines that there is an abnormality in any one of the rotation pair parts 31 to 34 in the link actuator main body 1 based on the measurement result of the measurement unit 5.

According to the link actuator having this configuration, the control device 2 includes the abnormality detection mechanism 4, the abnormality detection mechanism 4 includes the measurement portion 5, the measurement portion 5 measures a certain state value of the link actuator main body 1 affected by the abnormality of the rotation pair portions 31 to 34, and the determination portion 6 determines the presence of the abnormality in any one of the rotation pair portions 31 to 34 of the link actuator main body 1 based on the measurement result of the measurement portion 5. Therefore, it is possible to easily detect a reduction in rigidity and positioning accuracy caused by an assembly error or a long-term operation of the rotary pair parts 31 to 34 constituted by the bearing 23 or the peripheral portion thereof of the link actuator main body 1 without disassembly and even in a case of continuing the operation.

In the present invention, the measuring unit 5 may measure the rigidity of the link actuator main body 1, and the determining unit 6 may determine the abnormality according to a rule determined by the measurement value of the measuring unit 5. The rigidity of the link actuator main body 1 is such a degree that a change in the posture of the link actuator main body 1 is hard to occur, and comprehensively acts as the rotational difficulty of the rigidity of each of the rotation pair parts 31 to 34, and is expressed as the rigidity of the link actuator main body 1.

The rigidity of the link actuator main body 1 is greatly affected by the assembly error of the bearings 23 of the rotation dual parts 31 to 34 or the wear caused by the long-term operation. Therefore, by measuring the rigidity of the link actuator main body 1 and determining an abnormality according to a predetermined rule, it is possible to detect an abnormality of the rotation pair portions 31 to 34 of the link actuator main body 1 with high accuracy. The predetermined rule may be set arbitrarily, but for example, a reference value determined from a reference value determined in design or a measurement value collected at normal time may be compared with a current measurement value, and when the reference value is within an allowable range, it may be determined as abnormal. Whether or not the threshold value is within the allowable range may be determined based on whether or not the threshold value is exceeded as a reference value. Further, the determination of whether or not abnormality is present may be performed by a plurality of measurements and comparisons.

When the rigidity is measured to determine an abnormality, the measuring section 5 may measure a natural frequency of the link actuator main body 1 and estimate the rigidity from the natural frequency. The rigidity of the link actuator body 1 is related to the natural frequency, and decreases as the natural frequency decreases. Therefore, by using the measured value of the natural frequency of the link actuation device body 1, it is possible to determine an abnormality of the link actuation device body 1. When the measured value of rigidity is used, the measured value of rigidity can be confirmed by using the inspection of the actuation test immediately after assembly or the measurement during actuation, and therefore, shipment of defective products such as poor actuation can be prevented.

In the case where the rigidity is measured to determine an abnormality, the measuring unit 5 may measure the torque of the attitude control drive source 11 and estimate the rigidity of the link actuator main body 1 based on the measured torque. The rigidity of the rotation pair parts 31-34, i.e., the difficulty of rotation, is expressed as the torque of the attitude control drive source 11. Therefore, the torque of the attitude control drive source 11 can be measured, and the rigidity of the link actuator main body 1 can be estimated from the measured torque. Thus, assembly errors can be detected, and the confirmation operation can be simplified. Further, since it can be confirmed by inspection of an operation test immediately after assembly or measurement during operation, shipment of defective products such as operation failure can be prevented.

In the present invention, the determination unit 6 may include a storage unit 7, the storage unit 7 may store the state values in the plurality of postures of the link actuator main body 1 when the respective rotation pair parts 31 to 34 of the link actuator main body 1 are normal, and the determination unit 6 may compare a value determined from the stored state values in the plurality of postures with a state value measured by the measurement unit 5 to determine the abnormality.

By storing a state value in the normal state in advance and comparing the stored state value or a value determined from the state value with a current measurement value, it is possible to appropriately determine whether or not there is an abnormality. Further, since the loads acting on the rotation pair parts 31 to 34 are greatly different depending on the posture of the link actuator main body 1, the state values such as the rigidity of the bearings 23 having the rotation pair parts 31 to 34 are not abnormal depending on the posture. Therefore, by determining an abnormality in a plurality of postures, not only an initial failure such as an assembly error but also a change in long-term use due to wear or the like can be detected with high accuracy. In addition, the rotating pairs 31 to 34 in which the abnormality occurs may be specified.

In the present invention, the control device 2 may be provided with an abnormality determination operation command unit 3c, and the abnormality determination operation command unit 3c may drive the posture control drive source 11 so that the link actuator main body 1 is in a predetermined posture for abnormality determination. By performing the operation for abnormality determination after the assembly of the link actuator device or before the start of each operation, etc., based on the command from the abnormality determination actuator command unit 3c, it is possible to reliably detect not only an initial failure such as an assembly error, but also a change in long-term use due to wear, etc.

Any combination of at least two aspects disclosed in the claims and/or in the description and/or in the drawings is comprised in the present invention. In particular, any combination of two or more of the claims is also encompassed by the present invention.

Drawings

The invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are only for illustration and description and are not intended to limit the scope of the present invention. The scope of the invention is determined by the claims. In the drawings, like reference numerals designate identical or corresponding parts throughout the several views.

Fig. 1 is an explanatory view combining a block diagram of a control device and a perspective view of a link actuator main body in a link actuator according to embodiment 1 of the present invention;

fig. 2 is a perspective view of the link actuator main body in a posture different from that of fig. 1;

FIG. 3 is a front view of the link actuator body;

FIG. 4 is a front view of the link actuator body in a different attitude from that of FIG. 3;

FIG. 5 is a front view of a portion of the link actuator body;

FIG. 6 is a cross-sectional top view of the link actuator body;

fig. 7 is an enlarged cross-sectional view showing a part of fig. 6 in an enlarged manner;

fig. 8 is an enlarged sectional plan view showing a portion VIII of fig. 7 in a further enlarged manner;

FIG. 9 is a model view of a parallel linkage mechanism showing the body of the link actuator device in a straight line;

fig. 10 is a flowchart showing an example of abnormality detection of the link actuator device;

fig. 11 is a flowchart showing still another example of abnormality detection of the link actuator device;

fig. 12 is a flowchart showing another example of abnormality detection of the link actuator device;

fig. 13 is a flowchart showing still another example of abnormality detection of the link actuator device;

fig. 14 is a sectional plan view showing an example of an assembly error of the link actuator main body.

Detailed Description

An embodiment of the present invention will be described with reference to the drawings.

The link actuating device includes: a link actuator body 1 including a parallel link mechanism 10 and its attitude control drive sources 11(11-1, 11-2, 11-3); and a control device 2 for controlling the link actuator body 1.

< parallel Link mechanism 10>

As shown in fig. 3 and 4, the parallel link mechanism 10 connects the link hub 13 on the distal end side to the link hub 12 on the proximal end side in a posture changeable manner via the three-group link mechanism 14. The number of the link mechanisms 14 may be 4 or more.

Fig. 5 shows one of the link mechanisms 14. As shown in the figure, the link mechanism 14 is composed of a proximal end side end link member 15, a distal end side end link member 16, and a central link member 17, and forms a four-link-linked link mechanism composed of four rotation pairs 31 to 34. The proximal and distal end link members 15 and 16 are formed in an L shape, and one ends thereof are rotatably connected to the proximal and distal link hubs 12 and 13, respectively. The central link member 17 has the other ends of the base-end-side and tip-end-side end link members 15 and 16 rotatably connected to the respective ends thereof.

The parallel link mechanism 10 is a combination of two spherical link mechanisms, and the central axes O1, O2 of the respective rotation pairs 31, 32 of the link hubs 12, 13 and the end link members 15, 16, and the respective rotation pairs 33, 34 of the end link members 15, 16 and the center link member 17 intersect at spherical link centers PA, PB (fig. 5) on the proximal end side and the distal end side, respectively.

Further, distances from the respective pairs of rotation 31, 32 of the link hubs 12, 13 and the end link members 15, 16 to the respective spherical link centers PA, PB are also the same on the proximal and distal ends, and distances from the respective pairs of rotation 33, 34 of the end link members 15, 16 and the central link member 17 to the respective spherical link centers PA, PB are also the same. The central axes of the rotating pairs 33 and 34 of the end connecting members 15 and 16 and the central connecting member 17 may have a certain intersection angle γ or may be parallel to each other.

Fig. 6 is a cross-sectional top view of the link actuator. In the figure, the relationship between the central axis O1 of the respective rotation pairs 31 of the base end side link hub 12 and the base end side end link member 15, the central axis O2 of the respective rotation pairs 33 of the center link member 17 and the base end side end link member 15, and the base end side spherical link center PA is shown. That is, the point at which the center axis O1 intersects the center axis O2 is the spherical link center PA. In fig. 6, the angle α formed by the central axis O1 of the rotating pair portions 31 and 32 of the link hub 12(13) and the end link members 15(16) and the central axis O2 of the rotating pair portions 33 and 34 of the center link member 17 is 90 °, but the angle α may be an angle other than 90 °.

The three sets of linkages 14 are geometrically identical in shape in any pose. As shown in fig. 9, the geometrically identical shape means that a geometric model in which the link members 15, 16, 17 are represented by straight lines, that is, a model represented by the rotational pairs 31 to 34 and straight lines connecting the rotational pairs 31 to 34, is symmetrical with respect to the base end side portion and the tip end side portion of the central link member 17.

Fig. 9 is a diagram showing a set of link mechanisms 14 by straight lines. The parallel link mechanism 10 of the present embodiment is of a rotationally symmetrical type, and the positional relationship between the proximal-end-side link hub 12 and the proximal-end-side end link member 15, and the distal-end-side link hub 13 and the distal-end-side end link member 16 is rotationally symmetrical with respect to the center line C of the center link member 17. The central portions of the central link members 17 are located on a common orbit circle.

The link hub 12 on the base end side, the link hub 13 on the tip end side, and the three-group link mechanism 14 constitute a two-degree-of-freedom mechanism in which the link hub 13 on the tip end side is rotatable about two orthogonal axes with respect to the link hub 12 on the base end side. In other words, the link hub 13 on the distal end side rotates with respect to the link hub 12 on the proximal end side in a two-degree-of-freedom freely-changeable posture. This two-degree-of-freedom mechanism is compact, and the movable range of the link hub 13 on the tip side relative to the link hub 12 on the base side can be made wide.

For example, straight lines passing through the spherical link centers PA and PB and intersecting at right angles with the center axes O1 (fig. 6) of the respective rotation pair parts 31 and 32 of the link hubs 12 and 13 and the end link members 15 and 16 are taken as the center axes QA and QB of the link hubs 12 and 13. At this time, the maximum value of the angle θ between the central axis QA of the base end side link pivot hub 12 and the central axis QB of the tip end side link pivot hub 13 may be about ± 90 °. The rotation angle Φ of the front end side link pivot boss 13 with respect to the base end side link pivot boss 12 can be set in the range of 0 ° to 360 °. The fold angle θ is a vertical angle at which the central axis QB of the link pivot hub 13 on the tip side is inclined with respect to the central axis QA of the link pivot hub 12 on the base end side. The pivot angle Φ is a horizontal angle at which the center axis QB of the link pivot hub 13 on the tip side is inclined with respect to the center axis QA of the link pivot hub 12 on the base side.

The posture of the distal-side link hub 13 is changed with respect to the proximal-side link hub 12 with the intersection O of the central axis QA of the proximal-side link hub 12 and the central axis QB of the distal-side link hub 13 as the rotation center. In a state (fig. 3) where the central axis QA of the base end side link hub 12 and the central axis QB of the tip end side link hub 13 are located at the origin position on the same straight line, the tip end side link hub 13 faces directly downward. Fig. 1 and 3 show a state in which the center axis QB of the link hub 13 on the distal end side is at an operating angle with respect to the center axis QA of the link hub 12 on the proximal end side. Even if the posture changes, the distance L (fig. 9) between the spherical link centers PA and PB on the base end side and the tip end side does not change.

When each link mechanism 14 satisfies the following conditions 1 to 5, the proximal-end-side link hub 12 and the proximal-end-side end link member 15 operate in the same manner as the distal-end-side link hub 13 and the distal-end-side end link member 16 in view of geometrical symmetry. Thus, when the rotation is transmitted from the base end side to the distal end side, the parallel link mechanism 10 functions as a constant velocity universal joint in which the base end side and the distal end side rotate at the same rotation angle and rotate at the same speed.

(condition 1) the angles and lengths of the central axes O1 of the link hubs 12, 13 and the rotation pair parts 31, 32 of the end link members 15, 16 in each link mechanism 14 are equal to each other.

(condition 2) the central axes O1 of the rotation pairs 31, 32 of the link hubs 12, 13 and the end link members 15, 16 and the central axes O2 of the rotation pairs 33, 34 of the end link members 15, 16 and the center link member 17 intersect at the spherical link centers PA, PB on the base end side and the tip end side.

(condition 3) the base end side end link member 15 and the tip end side end link member 16 have the same geometry.

(condition 4) the base end side portion and the distal end side portion of the central link member 17 have the same geometry.

(condition 5) the angular positional relationship between the central link member 17 and the end link members 15 and 16 with respect to the symmetrical plane of the central link member 17 is the same on the base end side and the tip end side.

As shown in fig. 3, the base end side link hub 12 includes a base end member 20 and three rotation support members 21 provided integrally with the base end member 20. The three rotation support members 21 are arranged at equal intervals in the circumferential direction. Each rotation support member 21 is rotatably connected to a rotation shaft 22 whose axial center intersects with the central axis QA of the link hub 12 on the base end side. One end of the proximal end side end link member 15 is connected to the rotary shaft 22.

The front end side link hub 13 includes a flat plate-shaped front end member 50 and three rotation support members 51 provided at equal intervals in the circumferential direction on the inner surface of the front end member 50. A rotation shaft 52 having an axial center intersecting the central axis QB of the link hub 13 on the front end side is rotatably connected to each rotation support member 51. One end of the end link member 16 on the tip side is connected to the rotating shaft 52 of the link hub 13 on the tip side. A rotating shaft 55 rotatably connected to the other end of the center link member 17 is connected to the other end of the end link member 16 on the front end side. The rotary shaft 52 of the link hub 13 on the front end side and the rotary shaft 55 of the central link member 17 are also in the same shape as the rotary shaft 35, and are rotatably connected to the other ends of the rotary support member 51 and the central link member 17 via two bearings (not shown).

< rotating dual part 31 (between link hub 12 on the base end side and end link member 15 on the base end side) >

Fig. 6 shows a cross section of the end link member 15 on the base end side, the attitude control drive sources 11, and the relationship between the link hubs 12 on the base end side. Fig. 7 is an enlarged cross-sectional view of a part thereof, and fig. 8 is a further enlarged cross-sectional view of a part thereof.

The base end side link hub 12 is provided with three rotation shaft support members 21 for supporting the base end side end link member 15, which are projected from the upper surface of the base end member 20. As shown in fig. 7 and 8, the rotary shaft 22 is rotatably supported by the rotary shaft support member 21 via two bearings 23 and 23 arranged in a plurality of rows, and one end of the end link member 15 on the proximal end side is fixed to the rotary shaft 22. The link hub 12 on the base end side and the connecting portion of the link member 15 on the base end side connected by the bearings 23, 23 constitute a rotation dual portion 31.

Specifically, a pair of bifurcated branch pieces 15a and 15b are provided at one end of the end link member 15 on the base end side, and a rotary shaft support member 21 and bearings 23 and 23 are interposed between the branch pieces 15a and 15 b. One end surface of an outer peripheral fitting member 24 fixed to the outer periphery of the large diameter portion of the rotary shaft 22 in a fitted state is in contact with the outer side surface of one branch piece 15 b. In this state, a fixing member 25 such as a bolt is inserted from the inside, and the branch piece 15b is fixed to the outer circumferential fitting member 24.

The bearings 23, 23 are rolling bearings such as angular ball bearings, and a spacer 30 (see fig. 8) is interposed between outer rings (not shown) of the bearings 23, 23. The thin shaft portion of the rotary shaft 22 is inserted through inner rings (not shown) of the bearings 23 and 23, and annular spacers 29 and 29 are interposed between the inner rings and the branch pieces 15a and 15 b. In this state, the branch pieces 15a and 15b, the inner rings of the bearings 23 and 23, and the spacers 29 and 29 are tightened by tightening a nut 27 (see fig. 7) screwed to the male screw portion 22a provided at the distal end of the slender shaft portion, thereby applying a preload to the bearings 23 and 23.

In fig. 3, the configuration of the rotation dual part 32 as the connection portion between the distal end side end link hub 13 and the distal end side end link member 16 is the same as the rotation dual part 31 between the proximal end side link hub 12 and the proximal end side end link member 15.

< rotating pair 33 (between end link member 15 and center link member 17 on the proximal end side) >

As shown in fig. 7, a pair of bifurcated branch pieces 15c and 15d are provided at the other end of the end link member 15 on the base end side, and the end of the central link member 17 is interposed between the branch pieces 15c and 15 d. Bearings 23, 23 composed of rolling bearings such as angular ball bearings are arranged in two rows at the end of the center link member 17, similarly to the rotation dual part 31 of the base end side link hub 12.

The outer ring of each bearing 23 is fixed to the central link member 17 in a fitted state, and the rotary shaft 35 is fitted to the inner ring. Similarly to the connection to the link hub 12 on the base end side, a spacer is interposed between the outer rings of both the bearings 23, 23. Spacers that contact the inner race are disposed on both sides of the arrangement of the bearings 23, 23. The rotary shaft 35 is a bolt having an external thread portion and a head portion. By screwing the nut 28 to the external thread portion, the pair of branch pieces 15c, 15d are fastened together with the bearings 23, 23 of the two rows, the spacer, and preload is applied to the bearings 23, 23. The rotating shaft 35 of this portion is rotatably supported and does not rotate, but may rotate.

The rotation pair 34 between the distal end side end link member 16 (see fig. 3) and the central link member 17 has the same configuration as the rotation pair 33 between the proximal end side end link member 15 and the central link member 17 described with reference to fig. 7.

< attitude control drive source 11>

As shown in fig. 3, the attitude control drive source 11 is a rotary actuator having a speed reduction mechanism 62, and is provided coaxially with the rotary shaft 22 on the lower surface of the base end member 20 of the base end side link hub 12. The attitude control drive source 11 and the speed reduction mechanism 62 are integrally provided, and the speed reduction mechanism 62 is fixed to the base member 20 by a drive source mounting member 63. In this example, the attitude control drive source 11 is provided on all of the three sets of link mechanisms 14, but if the attitude control drive source 11 is provided on at least two sets of the three sets of link mechanisms 14, the attitude of the front end side link hub 13 with respect to the base end side link hub 12 can be determined.

The parallel link mechanism 10 changes the posture by rotationally driving each posture control drive source 11. Specifically, when the attitude control drive source 11 is rotationally driven, the rotation is decelerated by the deceleration mechanism 62 and transmitted to the rotary shaft 22. Thereby, the angle of the base end side end link member 15 with respect to the base end side link hub 12 changes, and the posture of the tip end side link hub 3 with respect to the base end side link hub 2 changes.

< end effector (not shown in the figure) >

In fig. 1, an end effector (not shown in the figure) for working a working object (not shown in the figure) is attached to the front end side link hub 12, and the link actuator and the end effector constitute a working device. End effectors are, for example, coating nozzles, air nozzles, welding torches, cameras, gripping mechanisms.

< control device 2 (FIG. 1) >

The control device 2 controls the attitude of the parallel link mechanism 1 mainly by controlling the attitude control drive sources 11(11-1 to 11-3). The control device 2 is configured by, for example, a computer, a program executed by the computer, an electronic circuit, and the like. The control device 2 includes a control means 3 for controlling the posture and an abnormality detection means 4 for detecting an abnormality.

< control means 3>

The control mechanism 3 has: a control unit 3a that decodes and executes a control program; a normal operation command unit 3b and an abnormality determination operation command unit 3 c. The normal operation command unit 3b is configured by a control program for causing the link actuator main body 1 to perform attitude control for work or the like. The abnormality determination operation command unit 3c is configured by a control program for causing the link actuator main body 1 to perform attitude control for abnormality detection.

< abnormality detection means 4>

The abnormality detection mechanism 4 is a mechanism for detecting an abnormality in the dual rotation sections 31 to 34 of the link actuator main body 1, and includes a measurement section 5 and a determination section 6. Such an abnormality is, for example, an assembly error, wear, or the like of the bearing 23 or the spacer 30 or the spacer 29 around the bearing. In this example, the abnormality detection mechanism 4 further includes a data collection unit 8.

The measuring unit 5 is a mechanism for measuring a certain state value affected by an abnormality of the bearings 23 of the rotation dual parts 31 to 34 of the link actuator main body 1. Such a state value is, for example, the rigidity of the link actuator main body 1. The determination unit 6 determines that there is an abnormality in any one of the rotation pair units 31 to 34 of the link actuator main body 1 based on the measurement result of the measurement unit 5. The determination unit 6 determines an abnormality according to a rule determined based on the measurement value of the measurement unit 5.

< measurement section 5>

In the present embodiment, the measuring unit 5 measures the natural frequency of the link actuator main body 1, and estimates the rigidity of the link actuator main body 1 from the natural frequency. Specifically, the measurement unit 5 includes: a sensor 5a, the sensor 5a being provided on the link pivot hub 12 on the base end side of the link actuator main body 1; the rigidity estimating means 5b and the rigidity estimating means 5 are provided in a computer constituting the control device 2. The sensor 5a is, for example, a vibrating meter such as an acceleration pickup.

Instead of the measurement unit 5, the torque of the posture control drive source 11 may be measured, and the rigidity of the link actuator main body 1 may be estimated from the measured torque. In this case, as a mechanism for measuring the torque, for example, an ammeter (not shown in the figure) that detects the flow of the current through the attitude control drive source 11 is used, and the rigidity estimation mechanism 5b estimates the rigidity of the link actuator main body 1 based on the detected current.

< determination unit 6, storage unit 7, and data collection unit 8>

The determination unit 6 stores a state value (for example, rigidity as a reference) as a determination reference in the storage unit 7 as a reference value, and compares the reference value with the state value measured by the measurement unit 5 to determine an abnormality. In this case, the reference values of the plurality of postures of the link actuator main body 1 are stored in the storage unit 7.

The reference value stored in the storage unit 7 may be a value determined by design or simulation, or may be a state value such as rigidity or vibration frequency of the link actuator main body 1 when the respective rotation pair parts 31 to 34 of the link actuator main body 1 are normal. The data collection unit 8 stores state values of a plurality of postures of the link actuator main body 1 when the rotation pair parts 31 to 34 of the link actuator main body 1 are normal in the storage unit 7.

The abnormality determination operation command section 3c issues a command to drive the attitude control drive source 11 so that the link actuator main body 1 assumes a predetermined attitude for abnormality determination. As described above, the abnormality determination operation command unit 3c is configured by a control program executed by the control unit 3 a.

< action of Link actuating device body 1>

The link actuator body 1 of this embodiment is constituted by a parallel link mechanism 10 that rotates two degrees of freedom. The method is characterized in that: the rigidity of the link mechanism 14 and the link actuator main body 1 of each system changes according to the posture of the parallel link mechanism 10. When an abnormality occurs in the parallel link mechanism 10 of the link actuator main body 1, the rigidity of the link mechanism 14 and the rigidity (in other words, "resistance") of the rotating pair parts 31 to 34 of each series change. When the rigidity of the link mechanism 14 and the rotation pair parts 31 to 34 of each system changes, the natural vibration of the link actuator main body 1 changes, and the torque of each attitude control drive source 11 changes.

< action of abnormality determination >

As described above, the control device 2 includes the abnormality detection unit 4 that detects the link actuator main body 1. The abnormality detection unit 4 includes a measurement unit 5 that measures the rigidity of the link actuation device body 1, and a determination unit 6 that determines whether these values are normal or abnormal.

At the time of determination, the determination unit 6 has a storage unit 7, and the storage unit 7 stores the natural vibration or the torque as a state value at the normal time as a reference value, and therefore, by comparing the measurement values in various postures with the data as the reference value of the storage unit 7, abnormality can be detected. The rigidity of the link actuator main body 1 can be estimated from the natural frequency or the torque of the attitude control drive source 11. For example, when the rigidity is increased, the amplitude and frequency of the natural vibration are increased, and the driving torque is also increased. Therefore, the rigidity of the link actuator main body 1 can be estimated by measuring the natural vibration by the sensor 5a (for example, an acceleration pickup) for picking up the vibration mounted on the link actuator main body 1, or measuring the natural vibration or the torque according to the motor drive current of the attitude control drive source 11.

The sensor 5a in fig. 1 is attached to the link hub 12 on the base end side, but may be attached to the link hub 13 on the tip end side where the vibration increases. In the posture of the link hub 13 on the front end side of the link actuator in fig. 3, the three link mechanisms 14 support substantially equal loads, but when the posture of the link hub 13 on the front end side is changed as shown in fig. 4, the loads and moments of inertia supported by the three link mechanisms 14 are not equal, and therefore the rigidity of the entire link actuator main body 1 changes. Therefore, it is necessary to store the stiffness value in each posture.

Since the rigidity of the link actuator of this embodiment varies depending on the posture of the link actuator body 1, normal data in various postures is maintained. The "data" referred to herein is the reference value or a value from which the reference value is derived, and means the rigidity estimated from the natural vibration and the torque. The normal data is derived from a past test or simulation model, and a threshold value as a reference value for abnormality determination is determined based on the normal data and stored in the storage unit 7.

The abnormality detection of the abnormality detection mechanism 4 is performed in an inspection flow after assembly, during continuous operation, which is normal actuation, and in a confirmation process before the start of the continuous operation. Fig. 10 shows an example of a flowchart of an inspection flow after assembly, fig. 11 shows another example of a flowchart of an inspection flow after assembly, fig. 12 shows an example of a flowchart in a confirmation process before the start of continuous operation, and fig. 13 shows another example of a flowchart in continuous operation.

< inspection flow after assembly, flowchart of FIG. 10>

In the inspection flow after the link actuator is assembled, the measuring portion 5 measures data of the state value of the link actuator main body 1 in a certain posture (step Q1). The determination unit 6 compares the data with the threshold value stored in the storage unit 7 (step Q2). When it is determined as a result of the comparison that the posture is normal (step Q3: yes), the data collection unit 8 of the abnormality detection means 4 stores the measured data in the certain posture in the storage unit 7 (step Q4). The stored data is used as normal data for inspection in an inspection flow after the next assembly and is used as data unique to the link actuator for abnormality determination during continuous operation.

When the judgment unit 6 judges that there is an abnormality (NO in step Q3), a warning indicating the judgment result indicating the intention of the abnormality is displayed (step Q5). The display is performed in a liquid crystal display device (not shown in the figure) or the like provided in the control device 2. When the warning is given, the worker or a processed product (not shown) of the object combined with the link actuator is disposed of as an NG product (defective product) such as re-inspection, component replacement, or disposal.

< inspection flow after Assembly, flowchart of FIG. 11>

Although the series of inspection processes after assembly in fig. 10 repeats data measurement and normal/abnormal determination in a single posture, as in the example in fig. 11, after data measurement in each posture is performed in advance (step R1), normal/abnormal determination may be collectively performed (steps R2 and R3). On this occasion, data storage in each posture (step R4) and warning display (step R5) are also performed together.

< determination of abnormality in confirmation flow before continuous operation, flowchart of FIG. 12 >

When the link actuator performs continuous actuation as a normal operation, the link actuator is caused to perform an operation as a confirmation process for abnormality determination in accordance with a command from the abnormality determination operation command section 3 c. The operation of the confirmation process may be the same as the operation of the continuous operation, or may be an operation dedicated to the confirmation.

In this confirmation process, the data in each posture during the operation is measured by the measuring unit 6 at regular intervals or at regular operation steps (step S1), and compared with a threshold derived from the data held in the storage unit 7 at the time of the inspection flow (step S2). When it is determined as abnormal as a result of the comparison (YES in step S3), the link actuator is stopped and a warning is displayed (step S4). The measurement in each posture (step S1) may be performed not at regular intervals but every time a predetermined posture is set. Different values may be used for the threshold value at the time of inspection after assembly, at the time of confirmation process, or at the time of continuous operation. The normal time data may be used as both the stored normal time data and the initial data unique to the link actuator.

< determination of abnormality during continuous actuation, flowchart of FIG. 13 >

In the continuous operation, as in the confirmation process, the data in each posture is measured by the measuring unit 6 for a fixed period or at each fixed operation step (step T1), and compared with the threshold derived from the data stored in the storage unit 7 in the inspection flow (step T2). When it is determined as abnormal as a result of the comparison (YES in step T3), the link actuator is stopped and a warning is displayed (step T4).

The certain period may be, for example, every 1 hour. The fixed operation step may be performed every 1 step, or may be performed every plural operation steps. The "operation step" referred to herein is an operation that is a unit of changing the posture of the link actuator.

< specific example of the state in which the assembly error occurred: FIG. 14>

Fig. 14 shows a configuration in the above embodiment in which the mounting angles of the drive source mounting member 63 and the rotation support member 21 are changed to cause an assembly error. In the link actuator of this embodiment, during normal operation, as shown in fig. 6, the central axis O1 of the rotation pair part 31 of each base end side end link member 15 and the rotation support member 21 and the central axis O2 of the rotation pair part 33 of each base end side end link member 15 and the center link member 17 all intersect at the center of the base end side link hub 12.

As an example of the assembly error shown in fig. 14, the mounting angles of the drive source mounting member 63 and the rotation support member 21 are changed, and the central axis O1 of the rotation pair part 31 of each base end side end link member 15 and the rotation support member 21 and the central axis O2 of the rotation pair part 33 of each base end side end link member 15 and the center link member 17 do not intersect at the center of the base end side link hub 12.

In the state of fig. 14, when the attitude of the link hub 13 on the front end side is to be controlled by controlling the attitude control drive source 11, the mechanism is shifted and cannot be normally operated. Therefore, the natural vibration of the link actuator and the torque of the attitude control drive source 11 are different from normal. By measuring this natural vibration or torque, assembly errors can be detected.

In the link actuator shown in the present embodiment, bearings 23 are disposed as torque reducing mechanisms in the rotation dual parts 31 to 34. Further, the bearings 23 are arranged in a plurality of rows, and as shown in fig. 8, in order to obtain a distance between the outer rings of the bearings, a spacer 30 is interposed, and the inner ring of the bearing 23 is preloaded by bolts and nuts via the end link members 15 and the spacers 29 on the base end side, thereby improving the rigidity.

In such a configuration, when the bearing 23 is disposed on the central link member 17, it is considered that an assembly error occurs in which it is forgotten to place the spacer 30 between the bearings 23, 23 or two or more spacers 30 are disposed between the bearings 23, 23. Such a difference in the arrangement of the spacer 30 may cause a dimensional difference and apply an excessive force to the end link member 15 on the base end side, thereby causing deformation. Further, the accuracy, the life, and the vibration may be caused by a change in the rigidity of the rotating pair parts 31 to 34. The pad separation causes a decrease in accuracy and vibration due to a decrease in rigidity, and the overlapping of pads causes a decrease in life due to an increase in surface pressure.

It has been difficult to confirm a spacer arrangement error after the completion of assembling the link actuator. For example, decomposition is required for visual confirmation, and takes much time. In addition, it cannot be decomposed nondestructively. However, by using the natural frequency and the torque as in the above-described embodiment, nondestructive and simple detection is possible.

According to the above-described embodiment, by detecting an abnormality based on the natural vibration of the link actuator and the torque of the attitude control drive source in this manner, it is possible to easily detect an assembly error of the link actuator and a reduction in rigidity and positioning accuracy due to long-term operation without being disassembled and even when the operation is continued. The abnormality detection means 4 may detect an abnormality by using both the natural frequency and the torque.

As described above, the preferred embodiments have been described with reference to the drawings, but the present invention is not limited to the above embodiments, and various additions, modifications, and deletions can be made within the scope not departing from the spirit of the present invention. Therefore, such a scheme is also included in the scope of the present invention.

Description of reference numerals:

reference numeral 1 denotes a link actuator main body;

reference numeral 2 denotes a control device;

reference numeral 3 denotes a control mechanism;

reference numeral 3a denotes a control section;

reference numeral 3b denotes a normal operation command unit;

reference numeral 3c denotes an abnormality determination operation command unit;

reference numeral 4 denotes an abnormality detection mechanism;

reference numeral 5 denotes a measuring section;

reference numeral 6 denotes a judgment section;

reference numeral 7 denotes a storage section;

reference numeral 8 denotes a data collection unit;

reference numeral 10 denotes a parallel link mechanism;

reference numerals 11, 11-1, 11-2, and 11-3 denote attitude control drive sources;

reference numeral 12 denotes a link hub on the base end side;

reference numeral 13 denotes a link hub on the front end side;

reference numeral 14 denotes a link mechanism;

reference numeral 15 denotes a base end side end link member;

reference numeral 16 denotes a tip end link member on the tip end side;

reference numeral 17 denotes a central link member;

reference numeral 23 denotes a bearing;

reference numeral 29 denotes a spacer;

reference numeral 30 denotes a gasket;

reference numerals 31 to 34 denote rotation dual parts.