JP6976098B2 - Link actuated work equipment - Google Patents

Description

The present invention relates to a link-operated working device used for a device such as a medical device or an industrial device that requires high speed, high accuracy, and a wide operating range, a robot, or the like.

The articulated robots of Patent Documents 1 and 2 use a link actuating device for at least one of a plurality of joints so that the arm portions on both sides of the joints rotate relative to each other about two axes orthogonal to each other. ing. Work is performed on the work object by the end effector mounted on the tip of the arm.

The link actuating device includes a link hub on the proximal end side, a link hub on the distal end side, and three or more sets of link mechanisms, and the link hub on the distal end side rotates about two axes orthogonal to the link hub on the proximal end side. It constitutes a flexible two-degree-of-freedom mechanism. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub on the tip side can be widened. For example, the maximum bending 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 set. It can be set in the range of 0 ° to 360 ° (unlimited). By using the link operating device for at least one of the plurality of joints, smooth operation without a singular point is possible in the operating range of a bending angle of 90 ° and a turning angle of 360 °, and fine-grained operation can be performed. realizable. In addition, it can operate quickly, has high operation safety, and is suitable for use in work sites where people coexist.

In a work device using such a link actuating device, the end effector is positioned at a desired target position by controlling the attitude control drive source of the link actuating device and adjusting the bending angle and the turning angle.

Japanese Unexamined Patent Publication No. 2016-147350 Japanese Unexamined Patent Publication No. 2016-147351

However, the working device using the link operating device has the following problems.
That is, in the link actuating device, as described above, the link hub on the proximal end side and the link hub on the distal end side are connected by three or more sets of link mechanisms, but each link mechanism has an end on the proximal end side. It is composed of a part link member, an end link member on the distal end side, and a central link member, and each link member is connected by a rotation axis. Further, in the case of the examples of Patent Documents 1 and 2, a gear mechanism is used to transmit the power of the attitude control drive source to each link mechanism. For example, the gears of the gear mechanism are provided on the rotation shaft of the attitude control drive source and the end link on the proximal end side, respectively.
As described above, since the link actuating device is composed of a plurality of members, it is difficult to increase the rigidity. There is also the influence of the assembly accuracy of each member and the backlash of the gears. Therefore, the work device using the link actuating device has a problem that the end effector cannot be accurately positioned at a desired position.

An object of the present invention is to provide a link-operated working device capable of correcting a positioning accuracy defect due to a structural cause of the link-actuating device and capable of accurately positioning an end effector.

In the link actuating working device of the present invention, the link hub 33 on the distal end side is connected to the link hub 32 on the proximal end side so as to be able to change the posture via three or more sets of link mechanisms 34, and each of the link mechanisms 34 is connected. , The proximal end side and the distal end side end link members rotatably connected to the proximal end side link hub 32 and the distal end side link hub 33, respectively, and the proximal end side and the distal end side ends thereof. The other end of the link member has a central link member having both ends rotatably connected to each other, and is provided in two or more sets of link mechanisms 34 among the three or more sets of link mechanisms 34, and is provided on the base end side. A link actuating device 29 provided with an attitude control drive source 90 for arbitrarily changing the attitude of the link hub 33 on the distal end side with respect to the link hub 32.
An end effector 120 mounted on the link hub 33 on the tip side and performing work on the work object W,
The point of action on which the end effector 120 acts on the work object W is mounted on the link hub 33 on the tip side so as to be located in the field of view on the optical axis OA and within the depth of field, and the work is performed. An image pickup device 100 that captures an object W,
The image captured by the image pickup apparatus 100 is processed, a target position S to be matched with the action point P of the end effector 120 is detected, and a deviation between the target position S and the position of the action point P on the image is detected. Image processing device 110 for obtaining
When a control command is issued to the attitude control drive source 31 according to a given positioning command and the operation of the attitude control drive source 31 is completed, the position of the target position S and the position of the action point P determined from the image. The attitude control means 130 for causing the attitude control drive source 31 to correct the position of the tip side link hub so as to match.
To prepare for.

According to the link-operated working device having this configuration, the attitude control means 130 basically issues a control command to the attitude control drive source 31 according to a given positioning command, and the tip of the attitude control drive source 31. By changing the posture of the link hub 33 on the side, the action point P of the end effector 120 is positioned. The means for giving the positioning command to the attitude control means 130 is, for example, the attitude control means 130, an operation program stored in the upper control means (not shown), a teaching console 131, or the like.
When the end effector 120 is positioned, the positioning accuracy may not be obtained due to play or the like of each part of the link actuating device 29, but this is corrected by using image processing as follows.
The image processing device 110 processes the image captured by the image pickup device 100, detects a target position S for locating the action point P of the end effector 120 according to a predetermined rule, and uses the target position S and the image to detect the target position S. The deviation from the determined point of action P is obtained. The "defined rule" is, for example, a rule for feature extraction in which a predetermined plane center, a predetermined corner portion, or a predetermined feature point in the work object W on the obtained image is set as a target position S. As a result, the target position S can be detected from the image.
The attitude control means 130 eliminates the deviation between the target position S and the action point P detected by the image processing when the attitude control drive source 31 completes its operation in accordance with the positioning control command. Is made to perform the positioning correction of the tip side link hub 33 on the attitude control drive source 31. The "point of action P determined from the image" can be set, for example, at the center of the image.

When image processing is used to detect the target position S, the image pickup device 100 for taking an image is arranged so that its optical axis OA coincides with the central axis of the link hub 33 on the tip side of the link actuating device. Is good. A method of obtaining the distance between the central axis of the link hub 33 on the tip side and the optical axis OA of the image pickup device 100 in advance and obtaining the target position S in consideration of this distance is also conceivable. The mounting position of 100 may change over time. In such a case, it is not efficient because a procedure for correcting the distance is required on a regular basis. Therefore, it is desirable to minimize the distance between the central axis of the link hub 33 on the distal end side and the optical axis OA of the image pickup apparatus 100, and to make them match if possible. Therefore, the present invention is a link-operated working device in which the central axis of the link hub 33 on the distal end side and the optical axis OA of the image pickup apparatus 100 are aligned with each other.

In the present invention, the image pickup device 100 is mounted on the link hub 33 on the tip side so that the point of action P of the end effector 120 is located in the field of view on the optical axis OA and within the depth of field. The target position S is imaged in order to adopt a control method in which the current target position S seen from the end effector 120 is measured, the deviation from the target position S is calculated, and the end effector 120 is positioned so that the displacement is small. If it is in the field of view of the device 100, the target position S can be actually measured, the deviation from the target position S can be calculated, and the end effector 120 can be positioned so that the deviation becomes small, so that high-precision positioning can be achieved. realizable.

Here, the point of action P and the target position S will be specifically described.
The point of action P is a point indicating the position of the end effector 120, and is determined according to the form of the end effector 120. For example, when the end effector 120 is a gripping device, it is defined in the vicinity of a point where the gripping device comes into contact with the work object W. Further, when the end effector 120 is a dispenser or a device that emits an energy beam, a jet, or the like such as a laser beam, the action point P is a point on the moving line of the discharged liquid, the energy beam, the jet, or the like. ..
The target position S is a target position for locating the action point P of the end effector 120, specifically, a point fixed on the work object W or the surrounding space as a positioning target for the end effector 120 to act. Is.
When the end effector 120 is correctly positioned at the target position S, the target position S and the point of action P coincide with each other. When the end effector 120 is a dispenser, the point of action P and the target position S coincide with each other when the movement line overlaps the target position S.

In the present invention, the end effector 120 may be fixed to the link hub 33 on the distal end side at a position offset from the central axis of the link hub 33 on the distal end side.
When the end effector 120 is at a position offset from the central axis of the link hub 33 on the distal end side, the optical axis OA of the imaging apparatus 100 ends when the imaging device 100 is provided on the central axis of the link hub 33 on the distal end side. The effector 120 does not block.
The central axis of the tip-side link hub 33 is the central axis of each rotation pair of the tip-side link hub 33 and the tip-side end link member, and the tip-side end link member and the center. When the point where the central axes of the rotation pairs of the link members intersect is referred to as the spherical link center of the link hub 33 on the distal end side, the link hub 33 on the distal end side and the end on the distal end side pass through the spherical link center. A straight line that intersects the central axis of the rotation pair of the link member at right angles.

In the present invention, the optical axis OA of the image pickup apparatus 100 may coincide with the central axis of the link hub 33 on the distal end side.
In this case, since it is easy to calculate the amount of deviation between the current target position S and the point of action P, the positioning control of the end effector 120 is easy.
Even if the optical axis OA of the image pickup apparatus 100 and the central axis of the link hub 33 on the distal end side do not match, the distance between the central axis of the link hub 33 on the distal end side and the optical axis OA of the image pickup apparatus 100 is set in advance. If it is found, the positioning control of the end effector 120 is possible by finding the target position S in consideration of this distance. However, in that case, since the mounting position of the image pickup apparatus 100 may change with time due to thermal influence or the like, it is necessary to periodically correct the distance. Therefore, it is desirable to minimize the distance between the central axis of the link hub 33 on the distal end side and the optical axis OA of the image pickup device 100, and the central axis of the link hub 33 on the distal end side and the optical axis OA of the image pickup device 100. It is more desirable to match.

In the present invention, the link hub 32 on the base end side is fixed to the attitude control drive source storage member 90, and even if the attitude control drive source 31 is housed inside the attitude control drive source storage member 90. good.
When the attitude control drive source 31 is housed inside the attitude control drive source storage member 90, the protruding portion of the link actuating work device is reduced, and a compact configuration can be realized. In addition, since the safety of the entire device is improved, it is suitable for use in a work site where humans coexist.

In the present invention, the image pickup device 100 is connected to the image processing device 110 via a video cable 101, and the video cable 101 is fixed to the central link member and is a cable guide member located inside each link mechanism 34. It may be guided to 104 and inserted into a connector 102 provided on the link hub 32 on the proximal end side.
In this case, since the video cable 101 is always held so as to pass through the inside of each link mechanism 34, it is possible to prevent the video cable 101 from interfering with other members such as the central link member and the end link member.

In the present invention, the link actuating device 29 may be mounted and an auxiliary positioning mechanism 3 for positioning the link actuating device 29 may be provided.
When the auxiliary positioning mechanism 3 is provided, the movable range of the end effector 120 is widened, and work can be performed on various parts of the work object W. In this case, there is a possibility that the action point P and the target position S are displaced due to the structural cause of the auxiliary positioning mechanism 3, but the attitude control drive source 31 is driven so that the action point P coincides with the target position S. By doing so, it is possible to accurately position the end effector 120.

In the present invention, the auxiliary positioning mechanism 150 for moving the work object W with respect to the end effector 120 may be provided.
When the auxiliary positioning mechanism 150 is provided, by moving the work object W, the end effector 120 can perform work on various parts of the work object W. In this case as well, there is a possibility that the action point P and the target position S are displaced due to the structural cause of the auxiliary positioning mechanism 150, but the attitude control drive source 31 is set so that the action point P coincides with the target position S. By driving, the end effector 120 can be positioned with high accuracy.

In the link actuating working device of the present invention, the link hub on the distal end side is connected to the link hub on the proximal end side so as to be able to change its posture via three or more sets of link mechanisms, and each of the link mechanisms is connected to the basic element. At the end link member on the proximal end side and the distal end side, one end of which is rotatably connected to the link hub on the distal end side and the link hub on the distal end side, and the other end of the distal end link member on the proximal end side and the distal end side. It has a central link member whose ends are rotatably connected to each other, and is provided in two or more sets of link mechanisms among the three or more sets of link mechanisms, and the link on the tip side with respect to the link hub on the base end side. A link actuating device provided with a drive source for attitude control that arbitrarily changes the attitude of the hub, an end effector mounted on the link hub on the tip side to perform work on a work object, and the work object. On the other hand, an image pickup device that is mounted on the link hub on the tip side so that the point of action on which the end effector works is located in the field of view on the optical axis and within the depth of view, and images the work object. An image processing device that processes an image taken by the image pickup device, detects a target position at which the action point of the end effector should match, and obtains a deviation between the target position and the position of the action point on the image. When the control command is issued to the attitude control drive source according to the given positioning command and the operation of the attitude control drive source is completed, the tip is aligned with the target position and the position of the action point. Since the position control means for causing the position control drive source to correct the position of the side link hub is provided, the end effector is accurately positioned without causing a positioning accuracy defect due to a structural cause of the link actuating device. be able to.

It is a figure which shows the schematic structure of the link actuating type working apparatus which concerns on 1st Embodiment of this invention. It is a front view which omitted a part of the link actuating apparatus of the link actuating type working apparatus. It is a front view of one state of the parallel link mechanism of the link actuating device. It is a front view of the different state of the parallel link mechanism. FIG. 2 is a sectional view taken along line VV of FIG. It is a figure which represented one link mechanism of the parallel link mechanism by a straight line. It is a figure which shows the state which the image pickup apparatus and the end effector are mounted on the parallel link mechanism. It is sectional drawing of VIII-VIII of FIG. (A) is a front view of the image pickup device and the end effector and its surroundings, and (B) is a left side view thereof. It is a figure which shows an example of the image taken by the image pickup apparatus. It is a figure which shows a different example of the image taken by the same image pickup apparatus. (A) is a front view of the image pickup device and other end effectors and their surroundings, and (B) is a left side view thereof. FIG. 12 is a left side view of an image pickup apparatus and an end effector and their surroundings showing a state different from that of FIG. 12B. It is a figure which shows the schematic structure of the link actuating type working apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the schematic structure of the link actuating type working apparatus which concerns on 3rd Embodiment of this invention.

An embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
1 to 9 show a first embodiment of the present invention.
As shown in FIG. 1, this link-actuated work device is a device that performs work on the work object W with the end effector 120, and includes a link-actuated device 29 for positioning the end effector 120. In addition to the end effector 120, the link actuating device 29 is equipped with an image pickup device 100. Further, apart from the mechanism unit including the link operating device 29, an image processing device 110, an attitude control means 130, and the like are provided.

<Link actuator>
First, the link actuating device 29 will be described.
As shown in FIG. 2, the link operating device 29 includes a parallel link mechanism 30 and an attitude control drive source 31 that operates the parallel link mechanism 30. 3 and 4 are views showing only the parallel link mechanism 30 taken out, and show different states from each other. As shown in FIGS. 2 to 4, the parallel link mechanism 30 is formed by connecting the link hub 33 on the distal end side to the link hub 32 on the proximal end side in a posture-changeable manner via three sets of link mechanisms 34. .. Note that FIG. 2 shows only one set of link mechanisms 34. The number of link mechanisms 34 may be 4 or more.

Each link mechanism 34 is composed of an end link member 35 on the proximal end side, an end link member 36 on the distal end side, and a central link member 37, and forms a four-node chain link mechanism composed of four rotating pairs. The end link members 35 and 36 on the proximal end side and the distal end side are L-shaped, and one end thereof is rotatably connected to the link hub 32 on the proximal end side and the link hub 33 on the distal end side, respectively. In the central link member 37, the other ends of the end link members 35 and 36 on the proximal end side and the distal end side are rotatably connected to both ends.

The parallel link mechanism 30 has a structure in which two spherical link mechanisms are combined, and is a structure in which the link hubs 32, 33 and the end link members 35, 36 are rotated pairs, and the end link members 35, 36 and the central link member 37. The central axes of each kinematic pair of rotation intersect at the spherical link centers PA and PB (FIG. 2) on the proximal end side and the distal end side, respectively. Further, on the proximal end side and the distal end side, the distances from the rotational pairs of the link hubs 32, 33 and the end link members 35, 36 and the spherical link centers PA, PB, respectively, are the same, and the end link members 35, The distances from each rotational pair of the 36 and the central link member 37 and the respective spherical link centers PA and PB are also the same. The central axis of each rotational pair of the end link members 35, 36 and the central link member 37 may have a certain crossing angle γ (FIG. 2) or may be parallel.

FIG. 5 is a cross-sectional view taken along the line VV of FIG. 2, in which the central axis O1 of each rotational pair of the link hub 32 on the proximal end side and the end link member 35 on the proximal end side and the central link member 37 are shown. The relationship between the central axis O2 of each rotational pair of the end link member 35 on the proximal end side and the spherical link center PA on the proximal end side is shown. That is, the point where the central axis O1 and the central axis O2 intersect is the spherical link center PA. The shapes and positional relationships of the link hub 33 on the distal end side and the end link member 36 on the distal end side are the same as in FIG. 5 (not shown). In the example of the figure, the central axis O1 of each rotation pair of the link hub 32 (33) and the end link member 35 (36), and each rotation pair of the end link member 35 (36) and the center link member 37. The angle α formed by the central axis O2 is 90 °, but the angle α may be other than 90 °.

The three sets of link mechanisms 34 have the same geometrical shape. As shown in FIG. 6, the geometrically identical shape is represented by a geometric model in which each link member 35, 36, 37 is represented by a straight line, that is, each rotation pair even and a straight line connecting these rotation pairs. It is said that the model has a shape in which the proximal end side portion and the distal end side portion are symmetrical with respect to the central portion of the central link member 37. FIG. 6 is a diagram showing a set of link mechanisms 34 as a straight line. The parallel link mechanism 30 of this embodiment is a rotationally symmetric type, and includes a link hub 32 on the proximal end side and an end link member 35 on the proximal end side, and a link hub 33 on the distal end side and an end link member 36 on the distal end side. The positional relationship is such that the central link member 37 is rotationally symmetric with respect to the center line C. The central portion of each central link member 37 is located on a common orbital circle.

With the link hub 32 on the proximal end side, the link hub 33 on the distal end side, and the three sets of link mechanisms 34, the link hub 33 on the distal end side is rotatable about two orthogonal axes with respect to the link hub 32 on the proximal end side. The degree mechanism is configured. In other words, the link hub 33 on the tip side with respect to the link hub 32 on the base end side is a mechanism capable of changing the posture with two degrees of freedom in rotation. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 33 on the distal end side with respect to the link hub 32 on the proximal end side can be widened.

For example, a straight line passing through the spherical link centers PA and PB and intersecting the central axis O1 (FIG. 5) of each rotational pair of the link hubs 32 and 33 and the end link members 35 and 36 at right angles is the central axis of the link hubs 32 and 33. In the case of QA and QB, the maximum value of the bending angle θ (FIG. 6) between the central axis QA of the link hub 32 on the proximal end side and the central axis QB of the link hub 33 on the distal end side can be set to about ± 90 °. can. Further, the turning angle φ (FIG. 6) of the link hub 33 on the distal end side with respect to the link hub 32 on the proximal end side can be set in the range of 0 ° to 360 °. The bending angle θ is the angle formed by the central axis QA of the link hub 32 on the proximal end side and the central axis QB of the link hub 33 on the distal end side, and the turning angle φ is the central axis QA of the link hub 32 on the proximal end side. The straight line obtained by projecting the central axis QB of the link hub 33 on the distal end side onto a plane perpendicular to is the angle formed by the reference straight line passing through the intersection of the plane and the central axis QA.

The posture of the link hub 33 on the distal end side is changed with respect to the link hub 32 on the proximal end side with the intersection O of the central axis QA of the link hub 32 on the proximal end side and the central axis QB of the link hub 33 on the distal end side as the center of rotation. Will be. FIG. 3 shows a state in which the central axis QA of the link hub 32 on the proximal end side and the central axis QB of the link hub 33 on the distal end side are on the same line, and FIG. 4 shows the central axis QA of the link hub 32 on the proximal end side. A state in which the central axis QB of the link hub 33 on the distal end side has a certain operating angle is shown. Even if the posture changes, the distance L (FIG. 6) between the spherical link centers PA and PB on the proximal end side and the distal end side does not change.

When each of the link mechanisms 34 satisfies the following conditions, the link hub 32 on the proximal end side and the end link member 35 on the proximal end side, the link hub 33 on the distal end side, and the end portion on the distal end side are met due to geometric symmetry. It moves in the same way as the link member 36. Therefore, when the rotation is transmitted from the proximal end side to the distal end side, the parallel link mechanism 30 functions as a constant velocity universal joint in which the proximal end side and the distal end side have the same rotation angle and rotate at a constant speed.
Condition 1: The angles and lengths of the central axes O1 of the rotational pair of the link hubs 32 and 33 and the end link members 35 and 36 in each link mechanism 34 are equal to each other.
Condition 2: The central axis O1 of the rotational pair of the link hubs 32, 33 and the end link members 35, 36 and the central axis O2 of the rotational pair of the end link members 35, 36 and the central link member 37 are on the proximal end side. And on the tip side, they intersect at the spherical link centers PA and PB.
Condition 3: The geometric shapes of the end link member 35 on the proximal end side and the end link member 36 on the distal end side are the same.
Condition 4: The geometric shapes of the proximal end side portion and the distal end side portion of the central link member 37 are the same.
Condition 5: The angular positional relationship between the central link member 37 and the end link members 35 and 36 with respect to the symmetrical plane of the central link member 37 is the same on the proximal end side and the distal end side.

As shown in FIGS. 2 to 4, the link hub 32 on the proximal end side is composed of a proximal end member 40 and three rotating shaft connecting members 41 integrally provided with the proximal end member 40. The base end member 40 has a circular through hole 40a in the central portion, and three rotating shaft connecting members 41 are arranged around the through hole 40a at equal intervals in the circumferential direction. The center of the through hole 40a is located on the central axis QA of the link hub 32 on the proximal end side. A rotating shaft 42 (FIGS. 3 and 4) whose axis intersects the central axis QA of the link hub 32 on the proximal end side is rotatably connected to each rotating shaft connecting member 41. One end of the end link member 35 on the base end side is connected to the rotating shaft 42.

As shown in FIG. 5, the rotary shaft 42 is rotatably supported by the rotary shaft connecting member 41 via two bearings 43. The bearing 43 is a ball bearing such as a deep groove ball bearing or an angular contact ball bearing. These bearings 43 are installed in a fitted state in the inner diameter holes 44 provided in the rotary shaft connecting member 41, and are fixed by press-fitting, bonding, crimping, or the like. The same applies to the types and installation methods of bearings provided in other rotary pair parts.

The rotary shaft 42 includes one end of the end link member 35 on the base end side and a fan-shaped bevel gear 45 which is a component of the axis orthogonal type reducer 77 described later so as to rotate integrally with the rotary shaft 42. Are combined. Specifically, a notch 46 is formed at one end of the end link member 35 on the base end side, and a rotary shaft connecting member is formed between the inner and outer rotary shaft support portions 47 and 48 which are both side portions of the cutout portion 46. 41 is arranged. The bevel gear 45 is arranged in contact with the inner side surface of the inner rotating shaft support portion 47. Then, from the inside of the rotary shaft 42, a through hole formed in the bevel gear 45, a through hole formed in the inner rotary shaft support portion 47, an inner ring of the bearing 43, and a penetration formed in the outer rotary shaft support portion 48. The bevel gear 45, the inner and outer rotary shaft support portions 47 and 48, and the inner ring of the bearing 43 are formed by inserting the holes in this order and using the nut 50 screwed to the head portion 42a of the rotary shaft 42 and the threaded portion 42b of the rotary shaft 42. Each is sandwiched and these are connected to each other. Spacers 51 and 52 are interposed between the inner and outer rotating shaft support portions 47 and 48 and the bearing 43, and a preload is applied to the bearing 43 when the nut 50 is screwed.

A rotation shaft 55 is coupled to the other end of the end link member 35 on the base end side. The rotary shaft 55 is rotatably connected to one end of the central link member 37 via two bearings 53. Specifically, a notch 56 is formed at the other end of the end link member 35 on the base end side, and a central link member is formed between the inner and outer rotating shaft support portions 57 and 58 which are both side portions of the notch 56. One end of 37 is arranged. Then, the rotary shaft 55 is inserted from the outside in the order of the through hole formed in the outer rotary shaft support portion 58, the inner ring of the bearing 53, and the through hole formed in the inner rotary shaft support portion 57, and the rotary shaft 55 is inserted. The head portion 55a and the nut 60 screwed to the threaded portion 55b of the rotating shaft 55 sandwich the inner and outer rotating shaft support portions 57 and 58 and the inner ring of the bearing 53, respectively, and connect them to each other. Spacers 61 and 62 are interposed between the inner and outer rotating shaft support portions 57 and 58 and the bearing 53, and a preload is applied to the bearing 53 when the nut 60 is screwed.

As shown in FIGS. 3 and 4, the link hub 33 on the tip side is composed of a tip member 70 and three rotating shaft connecting members 71 provided on the inner surface of the tip member 70 in a circumferentially equal arrangement. Will be done. The tip member 70 has a rectangular through hole 70a (FIG. 4) in the center. The center of the circumference on which each rotating shaft connecting member 71 is arranged is located on the central shaft QB of the link hub 33 on the distal end side. A rotating shaft 73 whose axis intersects the central axis QB of the link hub 33 on the distal end side is rotatably connected to each rotating shaft connecting member 71. One end of the end link member 36 on the tip side is connected to the rotation shaft 73 of the link hub 33 on the tip side. A rotary shaft 75 rotatably connected to the other end of the central link member 37 is connected to the other end of the end link member 36 on the distal end side. The rotary shaft 73 of the link hub 33 on the distal end side and the rotary shaft 75 of the central link member 37 are the rotary shaft connecting member 71 and the rotary shaft 75 via two bearings (not shown), respectively, like the rotary shafts 42 and 55. They are rotatably connected to the other ends of the central link member 37.

As shown in FIG. 2, the attitude control drive source 31 for operating the parallel link mechanism 30 is installed in the base end member 40 and is arranged inside the attitude control drive source storage member 90. The attitude control drive source accommodating member 90 is a shaft connection type arm portion in which a proximal end member 91 and a distal end member 92 arranged at the proximal end and the distal end are connected by a plurality of shafts 93. The tip end member 92 is the same member as the base end member 40. As shown in FIG. 5, the number of shafts 93 is the same as that of the attitude control drive source 31 (3 in this embodiment), and one shaft 93 is arranged between adjacent attitude control drive sources 31. There is. The attitude control drive source 31 and the shaft 93 are both arranged evenly in the circumferential direction.

The output shaft 31a of the attitude control drive source 31 is parallel to the central axis QA of the link hub 32 on the proximal end side. The number of attitude control drive sources 31 is three, which is the same as that of the link mechanism 34. The attitude control drive source 31 is composed of a rotary actuator, and the bevel gear 76 attached to the output shaft 31a and the fan-shaped bevel gear 45 attached to the rotating shaft 42 of the link hub 32 on the proximal end side are meshed with each other. There is. The gear mechanism including the pair of bevel gears 76 and 45 constitutes an axis orthogonal type speed reducer 77 in which the input side shaft and the output side shaft are orthogonal to each other. As shown in FIG. 5, the attitude control drive source 31 and the axis orthogonal type speed reducer 77 are arranged on the inner diameter side of the rotational kinematic pair portion of the link hub 32 on the proximal end side and the end link member 35 on the proximal end side. Has been done.

In this example, the same number of attitude control drive sources 31 as the link mechanism 34 are provided, but if at least two of the three sets of link mechanisms 34 are provided with the attitude control drive sources 31 The posture of the link hub 33 on the tip side with respect to the link hub 32 on the base end side can be determined.

Further, in this embodiment, the output shaft 31a of the attitude control drive source 31 is arranged in parallel with the central axis QA of the link hub 32 on the proximal end side, and is combined with the vertical axis speed reducer 77 for attitude control. The radial dimension of the portion where the drive source 31 is provided is small. The optimum arrangement of the direction and attitude control drive source 31 of the output shaft 31a can be selected according to the usage conditions of the link-operated working device.

The link operating device 29 operates the parallel link mechanism 30 by rotationally driving each attitude control drive source 31. Specifically, when the attitude control drive source 31 is rotationally driven, the rotation is transmitted to the rotary shaft 42 via an axis orthogonal speed reducer 77 composed of a pair of bevel gears 76 and 45, and the link hub 32 on the proximal end side is transmitted. The angle of the end link member 35 on the base end side with respect to the base end side is changed. As a result, the position and orientation of the link hub 33 on the distal end side with respect to the link hub 32 on the proximal end side are determined. Here, the axis orthogonal type speed reducer 77 is composed of a pair of bevel gears 76 and 45, but in addition, a mechanism using a worm gear and a pinion gear, a mechanism using a hypoid gear (trade name), or the like may be used.

<Attachment of imaging device and end effector to link operating device>
The image pickup device 100 and the end effector 120 are attached to the link hub 33 on the distal end side of the link actuating device 29 (FIG. 2), for example, as shown in FIG.

That is, the image pickup apparatus 100 is attached to the tip member 70 of the link hub 33 on the tip side so that the optical axis OA coincides with the central axis QB of the link hub 33 on the tip side. Specifically, the image pickup apparatus 100 is attached to the surface of the flange portion 100a facing the base end side of the tip member 70 in a state of being inserted into the through hole 70a of the tip member 70. The image pickup apparatus 100 is, for example, a digital camera.

The end effector 120 is attached to the tip member 70 at a position offset in the radial direction from the central axis QB of the link hub 33 on the tip side so as not to block the optical axis OA of the image pickup device 100. In that case, the point of action P of the end effector 120 is located on the optical axis OA of the image pickup apparatus 100 and within the depth of field of the image pickup apparatus 100.
The point of action P is a point that serves as a reference for the position of the end effector 120, and is determined according to the form of the end effector 120. For example, when the end effector 120 is a gripping device, it is defined in the vicinity of the point where the work object W is gripped.

<Connection between image pickup device and image processing device>
As shown in FIG. 1, the image processing device 110 is installed at a position distant from the link operating device 29, and includes a monitor 111 that displays an image taken by the image pickup device 100. The image pickup device 100 and the image processing device 110 are connected via a video cable 101. The video cable 101 has a role of sending the image signal of the image pickup device 100 to the image processing device 110 and a role of sending electric power to the image pickup device 100 via the image processing device 110.

The video cable 101 includes a first video cable 101a and a second video cable 101b. The first video cable 101a and the second video cable 101b are connected to each other by a connector 102 provided in the center of the through hole 40a of the base end member 40. Further, the central portion of the first video cable 101a is guided by the cable guide member 104 so as to pass through the inside of each link mechanism 34.

As shown in FIG. 8, the cable guide member 104 has a support portion 104a fixed to the central link member 37 of one link mechanism 34 and a C-shaped guide portion integrally provided at the tip of the support portion 104a. It becomes 104b. The cut 104ba of the guide portion 104b has a size that the first video cable 101a does not pass through, and an opening 104c through which the first video cable 101a passes is formed in the center. The center of the opening 104c is positioned to coincide with the center 106 of the orbital circle 105 of the central link member 37. In this way, by guiding the first video cable 101a by the cable guide member 104, the first video cable 101a is held so as to always pass through the inside of each link mechanism 34, and another member, for example, a central link member. It is possible to prevent interference with 37 and the end link members 35 and 36.

<Attitude control means>
As shown in FIG. 1, the attitude control means 130 is connected to the attitude control drive source 31 by a control cable 107, and supplies a drive current to the attitude control drive source 31 based on a positioning command of a control program (not shown). Supply. The control program may be stored in the storage means included in the attitude control means 130, or may be stored in a higher-level control means (not shown) for the link-operated working device.
The attitude control means 130 is connected to the image processing device 110 by a cable 108 so that the positioning of the stop position can be corrected, and is connected to the teaching console 131 to stop when controlled by the control program or the like. It is possible to teach the position. This teaching is, for example, an operation of numerical input by screen operation or the like. In addition to this, the attitude control drive source 31 can be directly operated by manual input from the teaching console 131.
The attitude control means 130 has a basic control unit 130a and an image correspondence correction unit 130b, and correction using image processing is performed by the image correspondence correction unit 130b, and other control, for example, control by the control program is basic control. Section 130a performs.

<End effector positioning control and correction by image processing>
The positioning control of the end effector 120 is basically performed by controlling the attitude control drive source 31 by the attitude control means 130 according to the control program as described above. This control may be feed forward control or feedback control.
When positioning in this way, the positioning accuracy may not be obtained due to play or the like of each part of the link operating device 29, but this is corrected by using image processing as follows.
The work object W is photographed by the image pickup apparatus 100, and the image is sent to the image processing apparatus 110. The image processing device 110 processes the image acquired from the image pickup device 100 to obtain the target position, and also obtains the deviation between the target position and the action point of the end effector 120 determined from the image. The "point of action determined from the image" can be set, for example, at the center of the image. In the image processing, for example, the captured image is converted into data that can be easily calculated such as a binary image, and the target position is obtained according to a rule determined from the image. The "defined rule" is, for example, to obtain a target position by feature extraction, and specifically, a predetermined plane center or a predetermined corner portion of the work object on the obtained image. The rules are such that a predetermined feature point is set as the target position. This makes it possible to detect the target position from the image. The image processing device 110 obtains the amount of deviation between the target position and the point of action obtained by this image processing, and the attitude control means 130 issues a control command based on the amount of deviation obtained from the image processing device 110 as a drive source for attitude control. Output to 31. As a result, the link actuating device 29 operates to correct the positioning of the end effector 120.

A specific example of correction by image processing will be described with reference to the figure.
FIG. 10 shows an example of an image captured by the image pickup apparatus 100 (see FIG. 9). This image R shows a state in which the point of action P and the target position S coincide with each other. The intersection of the vertical dotted line 112 and the horizontal dotted line 113 corresponds to the center of the image, and the area indicated by hatching indicates the work object W on which the end effector 120 works. Here, the shape of the work object W is a cube. FIG. 10 is a view of observing a certain plane A (dMx × dMy) in the work object W from the normal direction, and the optical axis of the image pickup apparatus 100 and the normal direction of the observation surface A coincide with each other. .. The end effector 120 (see FIG. 9) works with respect to the center of the observation surface A. When the action point P is located on the optical axis OA of the image pickup apparatus 100, the action point P comes to the center of the image as shown in FIG.

FIG. 11 shows a case where the target position S is deviated from the action point P due to a positioning error of the link operating device 29 (see FIG. 1) or the like. In such a case, the image G captured by the image pickup apparatus 100 is processed to obtain the target position S. This target position S is the current target position as seen from the end effector 120. The image processing device 110 calculates the amount of deviation between the current target position S and the point of action P, and transmits the calculation result to the attitude control means 130.
The posture control means 130 executes a correction operation of matching the target position S and the action point P based on the received deviation amount by the image correction corresponding correction unit 130b. As a result, as shown by the alternate long and short dash line, the point of action P and the target position S are made to coincide with each other. According to this method, if the current target position S is in the field of view of the image pickup apparatus 100, highly accurate positioning can be realized.

<Example of end effector>
As the end effector 120, for example, a coating device such as a dispenser or a light source device such as a laser device can be mounted. In that case, the point of action P of the end effector 120 corresponds to the adhesion position of the liquid to be discharged if it is a dispenser, and corresponds to the irradiation position of the laser beam if it is a laser device. In this way, since the point of action P of the end effector 120 can be obtained, highly accurate positioning is possible. As a result, defects such as deviation of the processing position can be prevented, and work efficiency can be improved.

As the end effector, the gripping device 140 shown in FIGS. 12 and 13 may be mounted in addition to the dispenser and the laser device. 12 (A) is a front view of the gripping device 140, and FIG. 12 (B) is a left side view. The gripping device 140 has a first gripping portion 141 and a second gripping portion 142, and both gripping portions 141 and 142 are brought close to each other to grip a work object. FIG. 13 is a left side view showing an open state in which both grip portions 141 and 142 are separated from each other.
The point of action P of the gripping device 140 corresponds to a substantially tip portion of the first gripping portion 141 and the second gripping portion 142. The image pickup device 100 photographs the work object W when the gripping device 140 is in the state shown in FIG. In this state, the first grip portion 141 and the second grip portion 142 do not interfere with photographing.

[Second Embodiment]
FIG. 14 shows a link actuating work device equipped with a link actuating device 29 and an auxiliary positioning mechanism for positioning the link actuating device 29. In this example, the auxiliary positioning mechanism is an articulated arm 3, and a link operating device type arm portion 15 having the same configuration as the link operating type working device of the first embodiment is mounted on the tip of the articulated arm 3. There is.

In the articulated arm 3, a plurality of (four in the example of the figure) arm portions 11 to 14 are arranged in series from the proximal end side to the distal end side, and the base unit 2 and the arm portion 11 on the most proximal side are adjacent to each other. The matching arm portions 11 to 14 are connected to each other via joint portions 21 to 24 so as to be relatively displaceable to each other. In the following description, the arm portions 11 to 14 are referred to as "first arm portion 11", "second arm portion 12", ... In order from the one on the proximal end side, and the joint portions 21 to 24 are referred to as each joint portion 21 to 24. "First joint portion 21", "second joint portion 22", and so on, in order from the one on the proximal end side.

The first joint portion 21 connecting the base unit 2 and the first arm portion 11 is a first arm portion with respect to the base unit 2 around a rotation axis 7 orthogonal to the installation surface 5 of the base unit 2. It comprises a rotation mechanism that rotates 11 relative to each other. The rotational drive of the first arm portion 11 is performed by a drive source 21a such as a motor provided in the base unit 2.

The second joint portion 22 connecting the first arm portion 11 and the second arm portion 12 is a second arm with respect to the first arm portion 11 around a rotation axis 8 parallel to the installation surface 5. It consists of a rotation mechanism that rotates the portion 12 relative to each other. The rotational drive of the second arm portion 12 is performed by a drive source 22a such as a motor provided in the first arm portion 11.

The third joint portion 23 connecting the second arm portion 12 and the third arm portion 13 has a second arm portion 12 around a rotation shaft 9 parallel to the rotation shaft 8 of the second joint portion 22. It is composed of a rotation mechanism that relatively rotates the third arm portion 13 with respect to the third arm portion 13. The rotational drive of the third arm portion 13 is performed by a drive source 23a such as a motor provided in the second arm portion 12.

The fourth joint portion 24 that connects the third arm portion 13 and the fourth arm portion 14 rotates relative to the third arm portion 13 by rotating the fourth arm portion 14 around the rotation axis 10. It consists of a mechanism. The rotational drive of the fourth arm portion 14 is performed by a drive source 24a such as a motor provided in the third arm portion 13. The fourth arm portion 14 is composed of a storage member 90 for a drive source for attitude control of the link actuating device type arm portion 15.

This link actuating working device has one degree of freedom of the first joint portion 21 composed of a rotation mechanism, one degree of freedom of the second joint portion 22 composed of the rotation mechanism, and one degree of freedom of the third joint portion 23 composed of the rotation mechanism. It is composed of a total of 6 degrees of freedom, including 1 degree of freedom, 1 degree of freedom of the fourth joint portion 24 composed of a linear motion mechanism, and 2 degrees of freedom of the link actuating device 29. With a configuration of 6 degrees of freedom, movements similar to those of a human hand are possible.

In this way, if the auxiliary positioning mechanism including the articulated arm 3 for positioning the link actuating device 29 is provided, the movable range of the end effector 120 is widened, and work can be performed on various parts of the work object W. Can be done. In this case, there is a possibility that the action point P and the target position deviate from each other due to the structural cause of the articulated arm 3, but the attitude control drive source 31 is driven so that the action point P coincides with the target position S. This makes it possible to accurately position the end effector 120.

[Third Embodiment]
FIG. 15 shows a link-operated working device provided with an auxiliary positioning mechanism for moving the work object W with respect to the end effector 120. In this example, the auxiliary positioning mechanism is a uniaxial linear motion mechanism 150 that moves the end effector 120 in the vertical direction. The auxiliary positioning mechanism may be a linear motion mechanism (not shown) that moves the end effector 120 in the uniaxial or biaxial direction along the horizontal plane, or a combination thereof with a vertical linear motion mechanism. There may be. Further, the auxiliary positioning mechanism may include a rotation mechanism. The link actuating device type mechanism unit 151 other than the auxiliary positioning mechanism has the same configuration as the link actuating working device of the first embodiment.

In this way, if the auxiliary positioning mechanism for moving the work object W with respect to the end effector 120 is provided, the end effector 120 can move the work object W to various parts of the work object W. You can work on it. In this case as well, there is a possibility that the action point P and the target position deviate due to the structural cause of the auxiliary positioning mechanism, but the attitude control drive source 31 is driven so that the action point P coincides with the target position. Therefore, it is possible to accurately position the end effector 120.

Although the embodiments for carrying out the present invention have been described above based on the examples, the embodiments disclosed here are exemplary in all respects and are not limiting. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

3 ... Articulated arm (auxiliary positioning mechanism)
15 ... Link actuating device type arm 29 ... Link actuator 30 ... Parallel link mechanism 31 ... Attitude control drive source 32 ... Base end side link hub 33 ... Tip side link hub 34 ... Link mechanism 35 ... Base end side End link member 36 ... End link member 37 on the tip side ... Central link member 90 ... Attitude control drive source storage member 100 ... Image pickup device 101 ... Video cable 102 ... Connector 104 ... Cable guide member 110 ... Image processing device 120 ... End effector 130 ... Attitude control means 140 ... Gripping device (end effector)
150 ... Linear mechanism (auxiliary positioning mechanism)
OA ... Optical axis P ... Point of action QB ... Central axis W of the link hub on the tip side ... Work object

Claims (7)

The link hub on the distal end side is connected to the link hub on the proximal end side so as to be able to change its posture via three or more sets of link mechanisms, and each of the link mechanisms is connected to the link hub on the proximal end side and the distal end side, respectively. A center where both ends are rotatably connected to the other ends of the proximal and distal end link members, one end of which is rotatably connected to the link hub, and the other ends of these proximal and distal end link members. A posture control having a link member and provided in two or more sets of link mechanisms among the three or more sets of link mechanisms to arbitrarily change the posture of the tip side link hub with respect to the base end side link hub. A link actuator equipped with a drive source for
An end effector mounted on the tip member of the link hub on the tip side and performing work on a work object,
The point of action on which the end effector works on the work object is mounted on the tip member of the link hub on the tip side so as to be located in the field of view on the optical axis and within the depth of field, and the work is performed. An image pickup device that captures an object and
An image processing device that processes an image taken by the image pickup device, detects a target position at which the action point of the end effector should match, and obtains a deviation between the target position and the position of the action point on the image. ,
When a control command is issued to the attitude control drive source according to a given positioning command and the operation of the attitude control drive source is completed, the tip side so that the target position and the position of the action point match. It is provided with an attitude control means for causing the attitude control drive source to perform position correction of the link hub .
The end effector is attached to the surface of the tip member on the tip end side, and is attached to the surface of the tip member.
The image pickup device is attached to the surface of the tip member on the base end side, and is inserted into a through hole formed in the central portion of the tip member and extends to the tip end side of the tip member.
Link actuated work equipment. In the link-operated working device according to claim 1, the end effector is a link-actuated working device fixed to the link hub on the tip side at a position offset from the central axis of the link hub on the tip side. The link-operated working device according to claim 1 or 2, wherein the optical axis of the imaging device coincides with the central axis of the link hub on the distal end side. In the link-operated working apparatus according to any one of claims 1 to 3, the link hub on the base end side is fixed to the attitude control drive source accommodating member, and the attitude control drive source accommodating member. A link-operated work device in which the drive source for attitude control is housed. In the link-operated working device according to any one of claims 1 to 4, the image pickup device is connected to the image processing device via a video cable, and the video cable is fixed to the central link member. A link-operated working device that is guided by a cable guide member located inside each of the link mechanisms and inserted into a connector provided on the link hub on the base end side. The link-operated working device according to any one of claims 1 to 5, wherein the link-acting device is mounted and the link-operated working device is provided with an auxiliary positioning mechanism for positioning the link-acting device. The link-operated working device according to any one of claims 1 to 6, further comprising an auxiliary positioning mechanism for moving the work object with respect to the end effector.

Images