JP2015100902A - Robot hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect force added from the direction different from the main detection direction of strain detection means among force added to a finger part, by using only one strain detection means.SOLUTION: A robot hand 100 comprises a finger part 10 and a force detection mechanism for detecting forces F1-F3 added to the finger part 10, and the force detection mechanism comprises a strain gauge 14 for detecting strain generated in the finger part 10 when the force is added to the finger part 10 and a beam structure 15a installed in the finger part 10 and amplifying the strain in the other two directions different from the main detection direction D of the strain gauge 14, and the strain gauge 14 is installed in the beam structure 15a.

Description

  The present invention relates to a robot hand.

  In general, a strain gauge as a strain detecting means for detecting a force applied to the finger portion is attached to a finger portion of a robot hand having a function of gripping an object. For example, in the robot hand described in Patent Document 1, a plurality of strain gauges are attached near the joints of the respective finger portions. The strain gauge detects a strain generated in a link supported by the joint of each finger portion, and based on this strain, an actuator that moves the finger portion is controlled to adjust a gripping force of the robot hand.

JP 2008-183716 A

  However, a conventional strain gauge such as the strain gauge of the robot hand of Patent Document 1 measures only the force applied to the finger from the main detection direction, with one direction gripping an object as the main detection direction. For example, as shown in FIG. 5, a single strain gauge 34a is attached to the cover member 35 attached to the side portion of the finger 30 of the robot hand, and the strain gauge 34a is in one direction D for gripping an object. Let 'be the main detection direction. Here, the force received by the finger portion 30 from the direction D ′ for gripping the gripping object is defined as F1 ′. Further, the force applied to the side surface of the finger part 30 from the lateral direction is F2 '. Further, the force received by the finger portion from the length direction of the finger portion 30 is F3 ′. The cover member 35 has a structure in which distortion due to the forces F2 'and F3' hardly occurs. That is, the strain gauge 34a can detect the strain generated by the force F1 ', but cannot detect the forces F2' and F3 'from directions other than the main detection direction. Therefore, a single strain gauge 34a detects a so-called “stick finger” in which an object other than the object to be grasped, that is, an obstacle hits the fingertip in the length direction of the finger part, or an obstacle collision from the side of the finger part. Can not do it.

  On the other hand, in order to detect a collision of a finger or an obstacle from a direction other than the direction of gripping an object, for example, as shown in FIG. 6, three strain gauges 34a and 34b corresponding to forces in three directions perpendicular to each other, as shown in FIG. , 34 c can be attached to the finger part 30. The strain gauges 34a, 34b, and 34c attached to the periphery of the finger part 30 are the force F1 ′ when the robot hand grips the object, and the force F2 when the obstacle hits the side surface of the finger part 30, respectively. 'And force F3 when an obstacle hits the fingertip' are detected.

  However, when a plurality of strain gauges are arranged on the finger as in the robot hand of FIG. 6, the manufacturing cost increases. Further, if a plurality of strain gauges are arranged near the movable part of the finger part, the wiring increases, so that there is a risk of disconnection.

  This invention is made in order to solve such a problem, and it aims at providing the robot hand which can detect a contact with a finger | toe part and objects other than a holding target object with a simple structure.

  In order to solve the above-described problems, a robot hand according to the present invention includes a finger part and a force detection mechanism that detects a force applied to the finger part, and the force detection mechanism applies a force to the finger part. A strain detection means for detecting strain generated in the finger portion at a time, and a beam structure which is attached to the finger portion and amplifies strain in other two directions different from the main detection direction of the strain detection means. The means is attached to the beam structure.

  Further, the beam structure of the robot hand according to the present invention may have at least two beam portions intersecting each other, and the strain detecting means may be attached to the intersecting portion of the two beam portions.

  According to the robot hand of the present invention, it is possible to detect contact between the finger portion and an object other than the grasped object with a simple structure.

It is a perspective view which shows typically the structure of the finger | toe part of the robot hand which concerns on Embodiment 1 of this invention. It is a figure which expands and shows typically the structure of the force detection mechanism in the finger | toe part of the robot hand shown in FIG. It is the figure which showed control of the finger | toe part of the robot hand shown in FIG. 1 as a flowchart. It is a figure which shows typically the structure of the force detection mechanism in the finger | toe part of the robot hand which concerns on Embodiment 2 of this invention. It is a perspective view which shows typically the structure of the finger | toe part of the robot hand by the conventional example. It is a perspective view which shows typically the structure of the finger | toe part of the robot hand by another conventional example.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
First, the structure of the finger part 10 of the robot hand 100 according to the present invention will be described with reference to FIG.
The finger portion 10 includes a support member 16 having a pair of aluminum plate-like portions 16a and 16b, an actuator 11 sandwiched between the plate-like portions 16a and 16b and housed and supported inside the support member 16, and an actuator 11 and a fingertip part 12 connected to 11. An ultrasonic motor is used for the actuator 11. The actuator 11 is electrically connected to the ECU 17. When the actuator 11 is driven based on a command from the ECU 17, the fingertip portion 12 can be appropriately rotated in the front-rear direction. In particular, when the robot hand 100 performs an object gripping operation, the ECU 17 issues a grip command to the actuator 11 and the fingertip portion 12 rotates in the direction D for gripping the object. On the other hand, when there is no grip command from the ECU 17, the fingertip portion 12 is not operating. In addition, a substantially square resin cover member 15 is attached to the support member 16 so as to cover the actuator 11 from the side surface of the finger portion 10 between the plate-like portions 16a and 16b. A beam structure 15 a to be described later is formed in the central portion of the cover member 15. A strain gauge 14 is affixed to the central portion of the beam structure 15a. The strain gauge 14 is electrically connected to the ECU 17.
Here, in FIG. 1, the force received by the finger unit 10 from the direction D of gripping the object is defined as F1. Further, the force applied to the side surface of the finger part 10 from the lateral direction with respect to the direction D is defined as F2. Further, the force received by the finger portion 10 from the length direction of the finger portion 10 is F3. The working directions of the forces F1, F2, and F3 are perpendicular to each other.
The strain gauge 14 constitutes strain detection means, and detects strain generated in the finger 10 when a force is applied to the finger 10. Note that the main direction in which the strain gauge 14 as the strain detection means detects strain, that is, the main detection direction of the strain gauge 14 is the direction D. Therefore, the strain gauge 14 mainly detects the force F <b> 1 that the finger unit 10 receives from the grasped object during the grasping operation of the robot hand 100.
Furthermore, the strain gauge 14 and the cover member 15 constitute a force detection mechanism. Further, the ECU 11 constitutes a control means, and can control the driving of the actuator 11 and the operation and position of the robot hand 100 based on the detection of strain by the strain gauge 14.

Next, the structure of the beam structure 15a formed in the cover member 15 is demonstrated using FIG.
The beam structure 15a has two beam portions 15b and 15c, and the beam portions 15b and 15c have the shape of an elongated plate-like support member. Each of the beam portions 15b and 15c is integrally formed in a shape that extends in an oblique direction with respect to the length direction of the finger portion 10 on which the force F2 acts and overlaps and crosses each other. A portion where the beam portion 15b and the beam portion 15c overlap and intersect forms a cross-shaped intersection portion 15e, and the strain gauge 14 is attached to the intersection portion 15e. Thereby, around the strain gauge 14, four triangular openings 15d formed between the beam portion 15b and the beam portion 15c are radially arranged.

Next, control of the finger unit 10 by the ECU 17 will be described with reference to the flowchart of FIG.
If the strain gauge 14 detects strain in step S1, it is determined in step S2 whether or not a grip command is issued from the ECU 17. If there is a grip command, that is, if the robot hand 100 is gripping an object, in step S3, the ECU 17 determines that the strain detected in step S1 is generated by the force F1. In step S4, the ECU 17 controls the actuator 11 to adjust the gripping force of the robot hand 100.

  On the other hand, if the ECU 17 does not issue a grip command in step S2, that is, if the robot hand 100 is moving, in step S5, the ECU 17 generates the strain detected in step S1 by the force F2 or F3. to decide. That is, the ECU 17 determines that forces F2 and F3 other than the gripping force F1 are applied to the finger unit 10. In step S6, the ECU 17 controls the actuator 11 and the driving means of the robot hand 100 to adjust the position and operation so that the fingertip portion 12 of the robot hand 100 does not hit the obstacle.

As described above, in the robot hand 100 according to this embodiment, when the cover member 15 receives any force of F1 to F3 through the finger portion 10, the cover member 15 is centered on the beam structure 15a having the opening 15d. In this structure, distortion is more likely to occur. Therefore, the beam structure 15a amplifies the strain generated by the forces F2 and F3 from the other two directions different from the main detection direction D of the strain gauge 14, and improves the detection sensitivity of the strain gauge 14 with respect to the forces F2 and F3. Therefore, not only the force F1 applied from the main detection direction D of the strain gauge 14 among the forces F1 to F3 applied to the finger part 10, but also the force F2 or F3 applied from a direction different from the direction D is one strain. It can be detected using a gauge 14. That is, the strain gauge 14 detects not only the force F1 when the robot hand 100 grips an object, but also the force F2 or F3 received when the finger 10 hits an obstacle while the robot hand 100 is moving. Can do. The ECU 17 appropriately controls the operation of the moving robot hand 100 based on the detection of the strain by the strain gauge 14, and prevents the actuator 11 from being damaged by the forces F2 and F3 acting on the finger unit 10. Therefore, the robot hand 100 can detect contact between the finger unit 10 and an object other than the object to be grasped with a simple structure using one strain gauge 14. As a result, the manufacturing cost of the robot hand 100 can be reduced and the number of wirings related to the strain gauge 14 can be reduced as compared with the case where a plurality of strain gauges are used.
Further, by providing the strain gauge 14 at the cross-shaped intersection 15e of the beam structure 15a having the two beam portions 15b and 15c, four openings 15d are formed around the strain gauge 14, and the strain gauge is formed. Strain is more likely to occur around 14.
Further, since the beam structure 15a is formed on the cover member 15 that is not a basic structural part of the finger part 10 of the robot hand 100, the strength of the finger part 10 main body is not affected.

Embodiment 2. FIG.
FIG. 4 shows the cover member 25 and the beam structure 25a formed on the cover member 25 in the robot hand 200 according to Embodiment 2 of the present invention. The overall configuration of the finger unit 20 of the robot hand 200 is the same as the configuration of the finger unit 10 of the robot hand 100 except for the structure of the cover member 25, and thus detailed description thereof is omitted.
The beam structure 25a has two beam portions 25b and 25c, and the beam portions 25b and 25c have the shape of an elongated plate-like support member. The beam portion 25b is integrally formed in a shape that is parallel to the length direction of the finger portion 10, that is, the direction in which the force F3 is applied, and the beam portion 25c extends perpendicularly to the length direction of the finger portion 10 and overlaps with each other. Has been. A portion where the beam portion 25b and the beam portion 25c overlap and intersect forms a cross-shaped intersection portion 25e, and the strain gauge 14 is attached to the intersection portion 25e. Thereby, around the strain gauge 14, four rectangular openings 25d formed between the beam portion 25b and the beam portion 25c are arranged.

As described above, the beam structure 25a of the robot hand 200 according to this embodiment amplifies the strain generated by the forces F2 and F3 from the other two directions different from the main detection direction of the strain gauge 14, as with the robot hand 100. Let And the beam structure 25a improves the detection sensitivity of the strain gauge 14 with respect to force F2, F3. Accordingly, not only the force F1 applied from the main detection direction D of the strain gauge 14 but also the force F2 or F3 applied from a direction different from the direction D can be detected using one strain gauge 14. That is, the robot hand 200 can detect contact between the finger unit 20 and an object other than the grasped object with a simple structure using one strain gauge 14.
Further, by providing the strain gauge 14 at the cross-shaped intersection 25e of the beam structure 25a having the two beam portions 25b and 25c, four openings 25d are formed around the strain gauge 14, and the strain gauge Strain is more likely to occur around 14. Moreover, since the beam structure 25a is formed on the cover member 25 that is not the basic structural part of the finger part 20, the strength of the main body of the finger part 20 is not affected.

In the first or second embodiment, the beam structure 15a or 25a has two beam portions 15b, 15c or 25b, 25c. However, the present invention is not limited to this, and the number of beam portions may be one or three or more. Good.
In the first or second embodiment, the beam structure 15a or 25b is formed on the cover member 15 or 25. However, the present invention is not limited to this, and only the beam portion of the beam structure is provided on the side surface of the finger portion. Good.
In the first or second embodiment, the shape of the opening provided for forming the beam structure on the cover member is not limited to a triangle or a quadrangle. That is, a polygonal or circular opening is appropriately provided so that a predetermined number of beam portions are formed in the cover member.

  10 finger part, 14 strain gauge (force detection mechanism, strain detection means), 15, 25 cover member (force detection mechanism), 15a, 25a beam structure, 15b, 15c, 25b, 25c beam part (beam structure), 15e, 25e Intersection.

Claims (2)

Fingers,
A force detection mechanism for detecting the force applied to the finger,
The force detection mechanism is
Strain detecting means for detecting strain generated in the finger when a force is applied to the finger;
A beam structure that is attached to the finger and amplifies the strain in the other two directions different from the main detection direction of the strain detection means;
The strain detecting means is a robot hand attached to the beam structure. The beam structure has at least two crossed beam portions;
The robot hand according to claim 1, wherein the strain detecting means is attached to an intersection of the two beam portions.

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