JP3044307B1 - Transport arm position error absorption sensor - Google Patents

Abstract

An elastic movable member is provided in order to assemble components smoothly when components are inserted into a component insertion opening by a transfer arm. In such a transfer apparatus, if the force of pressing the parts by the transfer arm is configured to be detected based on the output of a strain gauge attached to the elastic body of the elastic movable member, the apparatus becomes expensive. SOLUTION: An upper plate 3 fixed to a transfer arm 1 and a lower plate 4 provided with a component gripping portion 5 are connected by an elastic cylinder 8, and a magnet block 15 is attached to the upper plate 3, and a lower plate 4 is provided. Is provided with a Hall element 18, and both are arranged to face each other. When the component 9 is inserted into the component insertion hole 19 while being guided while being guided by the chamfered portion 24 provided on the periphery of the opening of the insertion hole 19, the pressing force F applied to the component 9 by the transport arm 1 is used together with the component 9. The lower plate 4 moves, and the Hall element 18 approaches the magnet block 15. The pressing force F can be detected by detecting the output voltage of the Hall element at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RC provided to absorb a position error at the tip of a transfer arm of a robot.
The present invention relates to a sensor for detecting a position error in C (Remote Center Compliance) or the like.

[0002]

2. Description of the Related Art In an assembling robot or the like, an article is gripped by a tip of a transfer arm, and is moved horizontally, for example, to a predetermined position above an assembly point, and then lowered vertically to transfer the conveyed article to a predetermined position. And assembling it. Such operations are not limited to the horizontal and vertical conveyance of the article as described above, and conveyance in various forms is performed for assembling in various postures. Not limited to this, similar operations are performed in various types of article transport devices.

In a transfer apparatus using such a transfer arm, for example, as shown in FIG. 4, a component 43 is gripped by a component grip portion 42 provided at the tip of the transfer arm 41, and, for example, from the position shown in FIG. When a component is inserted into the component insertion opening 44 having a center opening at a point moved D in the horizontal direction and H in the vertical direction, a position error occurs, and the component cannot be moved exactly D in the horizontal direction. As shown in FIG.
If the component is lowered in the vertical direction at the shifted position, the lower end of the component 43 contacts the opening edge of the component insertion opening 44 and cannot be further lowered, so that the component cannot be assembled. At this time, it is conceivable that the component insertion opening 44 is sufficiently large. However, in many cases, the component insertion opening 44 cannot be large because the accuracy of the component assembly product is deteriorated.

Therefore, as another measure, for example, FIG.
As shown in FIG. 7, a chamfered portion 45 is formed on the periphery of the component insertion opening 44, and when the component comes into contact with the periphery of the component insertion opening at a position close to the component insertion opening 44 as described above, the tip of the component comes into contact with the chamfered portion 45. The parts 43 by the lowering of the transfer arm 41
Is guided to the center side of the component insertion slot 44. At this time, when the component 43 is firmly fixed to the transfer arm 41, even if the component 43 falls, the chamfer 45
Therefore, for example, as shown schematically in FIG. 5, the transport arm 41 and the component gripper 42
An elastic movable member 46 is provided between them.

When the component 43 descends with the lower end of the component 43 in contact with the chamfered portion 45 as shown in FIG. 5A, the elastic movable member 4 as shown in FIG.
6, the component gripper 42 moves substantially horizontally, and the component 43
Is guided to the center of the component insertion slot 44.
Thereafter, as shown in FIG. 5C, the outer periphery of the component 43 is finally inserted while being guided into the inner periphery of the component insertion slot 44. The elastic movable member for performing such an operation is RCC
(Remote Center Compliance), which is widely used for robots for assembly work.

As an elastic movable member for absorbing the position error of the transfer arm as described above, for example, the one shown in FIG. 6 has been proposed. That is, the elastic movable member 5
0, an upper plate 53 provided with a projection 52 fixed to the transfer arm 51, and a lower plate 54 provided with a gripper 55 capable of gripping and detaching a component 59.
3 is provided with a plurality of fixing pins 56, for example, three. Similarly, a fixing pin 57 is provided on the lower plate 54 so as to oppose the fixing pin 56 of the upper plate 53, and between the opposing fixing pins 56, 57. An elastic cylinder 58 made of rubber or the like is arranged, and both fixing pins 5
6, 57 are inserted and fixed in the elastic cylinder 58 in the axial direction. In addition, one or more guide pins 60 are projected from the lower plate 54, and their tapered ends are inserted into guide holes 61 provided in the upper plate 53 so as to face the guide pins 60, and the lower plate 54 prevents excessive horizontal movement.

By providing the elastic movable member 50 as described above, the lower end of the component 59 is guided and guided by the chamfered portion of the insertion port while the lower end of the component 59 is being assembled at the time of assembling the component 59 as described above. When moving, the lower plate 54 of the elastic movable member 50 moves horizontally as shown in FIG.
At this time, at both ends of the elastic cylinder 58, the elastic cylinder 58 is held so as not to be able to move in the horizontal direction by the internal fixing pins 56, 57. It moves horizontally by the deformation and absorbs the movement in the pressing direction.

[0008]

The transfer arm 5 at this time
If the force 1 presses the component 59, that is, the force F by which the component is pressed by the elastic movable member 50 without the component being smoothly inserted into the insertion opening, is large, the component is damaged, and the member into which the component is inserted is also damaged. I do. For this reason, it is necessary to detect this pressing force, move the transfer arm when the force is large, and operate so that the center line of the component and the center line of the insertion port are more matched.

Conventionally, when detecting the force by which such a transfer arm presses a component, for example, as shown in FIG. 6, a strain gauge 6 is provided on the side of an elastic cylinder 58 of an elastic movable member.
Attempts have been made to measure the amount of deformation of the elastic cylinder 58 deformed according to the pressing force F of the component by the transfer arm 51 with the strain gauge 62 fixed. However, such a strain gauge 62 is expensive and causes an increase in the cost of the apparatus. Further, although a strain gauge is suitable for measuring a small amount of deformation, it is not necessarily suitable for use in a material having a large deformation amount such as the RCC.

On the other hand, it is conceivable to directly detect the force of pressing the component by the transfer arm by using a force sensor without providing the strain gauge as described above. However, rigidity is required for the entire apparatus, and it is difficult to apply the apparatus to a flexible deformable one such as the above-mentioned RCC.

Therefore, the present invention provides an accurate and inexpensive measurement of the force applied by a transfer arm in a transfer position error absorbing device using an elastic movable member such as an RCC provided to absorb a position error at the tip of the transfer arm. It is an object of the present invention to provide a sensor for a transfer arm position error absorbing device which can be used.

[0012]

According to the present invention, in order to solve the above-mentioned problems, according to the first aspect of the present invention, an upper plate fixed to a transfer arm and a lower plate provided with a component holding portion are elastically movable. In the transfer position error absorbing device connected by a member, a permanent magnet is fixed to the upper plate or the lower plate, and a Hall element is provided near the permanent magnet on the lower plate or the upper plate on the side opposite to the side on which the permanent magnet is fixed. This is a sensor for a transfer arm position error absorbing device, wherein the sensor is fixed, and a pressing force against a part of the transfer arm due to a transfer arm position error is detected by an output of the Hall element.

According to a second aspect of the present invention, the output characteristics of the transfer arm position error absorbing device according to the first aspect, wherein the output characteristics of the Hall element are selected by selecting the arrangement of the permanent magnets or the arrangement of the polarities of the permanent magnets. This is a sensor for use.

[0014]

FIG. 1 is a schematic view of an embodiment of the present invention. The entire structure of the RCC 20 provided on the transfer arm is the same as that shown in FIG. 6 shown as the conventional example, and the upper plate 3 having the projection 2 fixed to the transfer arm 1.
And a gripper 5 capable of gripping and detaching the component 9
And a lower plate 4 provided with a plurality of fixing pins 6 on the upper plate 3.
Similarly, a fixing pin 7 is provided on the lower plate 4 so as to face the fixing pin 6 of the upper plate 3, and an elastic cylindrical body 8 made of rubber or the like is arranged between the fixing pins 6 and 7 facing each other. Fixing pin 6,
7 is inserted and fixed in the elastic cylinder 8 in the axial direction. One or a plurality of guide pins 10 project from the lower plate 4, and the tapered tip of the guide pin 10 is
6 in that the lower plate 4 is inserted into a guide hole 11 provided so as to face the upper plate 3 to prevent excessive horizontal movement of the lower plate 4 with respect to the upper plate 3. In addition, inside the elastic cylinder 8, a plurality of discs are buried horizontally at intervals as needed, and further, elastic ribs are arranged around the elastic cylinder along the axial direction thereof. Is also good.

With respect to the RCC 20 having the above structure,
In the present invention, a magnet block 15 having a U-shaped magnet frame 14 is fixed to a lower end of a support rod 13 extending downward from the upper plate 3, and a support rod extending upward from the lower plate 4. A Hall element 18 is fixed to the bent end 17 of the 16. A gap 21 is provided between the upper and lower frames of the magnet frame 14 so that the permanent magnets 22,
23 is fixed, and the gap is formed to be larger than the height of the Hall element 18 but narrow within an allowable range.
As shown in FIG. 1, the Hall element 18 is disposed so as to enter the gap 21 between the permanent magnets 22 and 23 when the lower plate 4 is moving rightward in FIG. In addition, even when the permanent magnets enter the gap 21 between the permanent magnets, the permanent magnets 22 and 23 are set so as not to come into contact with each other. In addition, as a fixing means of the permanent magnet and the Hall element, various means other than the configuration shown in the schematic diagram of FIG. it can. Further, a lead wire is connected to an external control device by an appropriate means to the Hall element 18.

The arrangement of the polarities of the permanent magnets can be set arbitrarily. For example, as shown in FIG. 2A, the upper frame 25 of the magnet frame 14 has the N pole on the opening side of the magnet frame 14 and the opposite side. An upper magnet 26 arranged so that the side becomes an S pole is fixed, and a lower magnet 28 arranged oppositely to the magnet 26 is fixed to a lower frame 27, and a gap through which the Hall element 18 enters and exits between the two magnets. 21 are formed. With respect to the gap 21 between the magnets arranged as described above, the Hall element 18 moves from the illustrated position in the substantially horizontal direction as described above toward the center position of each magnet. The moving distance of the Hall element 18 at that time is represented by D.

As shown in FIG. 2B, the upper frame 25 and the lower frame 27 of the magnet frame 14 are provided.
Is provided with two magnets, and the magnet 30 located on the opening side of the magnet frame 14 of the upper frame 25 is
4 is arranged so that the center side is an N pole and the side in contact with the upper frame is an S pole, and the magnet 31 adjacent thereto is arranged with the polarity reversed. Similarly, the magnet 32 located on the opening side of the magnet frame 14 of the lower frame 27 has the S pole on the center side of the magnet frame, and the magnet 33 adjacent thereto is arranged with the polarity reversed. With respect to the gap 21 between the magnets arranged in this way, the Hall element 18 moves from the illustrated position toward the adjacent surface of the two adjacent magnets. The moving distance of the Hall element 18 at that time is represented by D. In addition to the arrangement of the magnets described above and the arrangement of the polarities of the magnets, the magnets can be arranged in various modes, and the arrangement of the polarities can be performed.

In the RCC in which the permanent magnet and the Hall element are arranged as described above, when the component 9 is inserted into the component insertion hole 19 by the transfer arm 1 as shown in FIG. The lower plate 4 of the RCC 20 moves rightward in the drawing against the return force of the elastic cylinder 8 due to the pressing force F of the transfer arm 1 and comes into contact with the chamfered portion 24 provided on the periphery of the opening of the hole 19. As a result, the Hall element 18 fixed to the lower plate 4 moves together and approaches the magnet or enters the gap between the opposed magnets.

At this time, the output voltage of the Hall element changes as shown in the graph of FIG. That is, FIG.
2A shows the output voltage corresponding to each embodiment shown in FIG. 2B and FIG. 2B shows the arrangement of magnets as shown in FIG.
In the arrangement of the polarities, the output voltage changes abruptly with respect to the moving distance D of the Hall element symmetrically with respect to the movement distance D of the Hall element, with the center of the magnet being the center of the change. On the other hand, in the arrangement of the magnets and the arrangement of the polarities as shown in FIG. Changes slowly. When it is desired to output a slight movement of the Hall element as a large output change by using such a change characteristic, it is desirable to select the magnet arrangement and the polarity arrangement as shown in FIG. Sometimes, they are arranged as shown in FIG. Therefore, these can be arbitrarily selected in accordance with the characteristics of the RCC, the mode of use, and the like, and can be further adapted to other modes by arranging other magnets and magnetic poles.

By measuring the output voltage of the Hall element as described above, the force F for pressing the component by the transfer arm can be detected. When the force is greater than a predetermined value, the control device (not shown) presses the component by the transfer arm. An operation such as stopping the operation and moving the component again can be performed.

In the above embodiment, the permanent magnet is fixed to the upper plate, and the Hall element is fixed to the lower plate. However, the two are arranged upside down, the permanent magnet is fixed to the lower plate, and the Hall element is fixed. It can be fixed to the upper plate.

[0022]

Since the present invention is constructed as described above, the invention according to claim 1 is a transfer arm position error absorbing device provided with an elastic movable member such as an RCC provided to absorb the position error at the tip of the transfer arm. In the apparatus, the force applied to the component by the transfer arm is converted into the movement amount of the transfer position error absorbing device, and the movement amount can be detected by the Hall element, and can be measured accurately and at low cost.

According to the second aspect of the present invention, the output characteristics of the Hall element are selected by selecting the arrangement of the permanent magnets or the arrangement of the polarities of the permanent magnets. Can be set to

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration and operation of a transport position error absorbing device and a sensor according to the present invention.

FIG. 2 shows various embodiments of a sensor of the apparatus.

FIG. 3 is an output characteristic diagram from a Hall element in various embodiments of the sensor.

FIG. 4 is a schematic view showing a state in which components are assembled by a transport device.

FIG. 5 is a schematic diagram showing an assembly state of components by a transfer device provided with a transfer position error absorbing device.

FIG. 6 is a schematic diagram showing an operation of a specific example in a conventional transfer position error absorbing device, and an example of a sensor for detecting a force on a part of a transfer arm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveying arm 2 Projection 3 Upper plate 4 Lower plate 5 Grasping part 6 Fixing pin 7 Fixing pin 8 Elastic cylinder 9 Parts 10 Guide pin 11 Guide hole 13 Support rod 14 Magnet frame 15 Magnet block 16 Support rod 17 Bending end 18 Hall element 20 RCC 21 Gap 22 Permanent magnet 23 Permanent magnet

Claims (2)

(57) [Claims] In a transfer position error absorbing device in which an upper plate fixed to a transfer arm and a lower plate provided with a component gripper are connected by an elastic movable member, a permanent magnet is fixed to the upper plate or the lower plate. A Hall element is fixed to the lower plate or upper plate on the side opposite to the side on which the permanent magnet is fixed, close to the permanent magnet, and the output of the Hall element detects a pressing force on a part of the transfer arm due to a transfer arm position error. A sensor for a transfer arm position error absorbing device, characterized in that: 2. The sensor for a transfer arm position error absorbing device according to claim 1, wherein the output characteristics of the Hall element are selected by selecting the arrangement of the permanent magnets or the arrangement of the polarities of the permanent magnets.