JP2015034733A - Robot hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect forces applied to a finger of a robot hand in plural directions while avoiding size increase of the robot hand.SOLUTION: A robot hand comprises: a finger part; an optical sensor attached to the finger part; and a control unit (ECU) connected to the optical sensor. The optical sensor is configured to detect a distance between paired light transmission/reception part and reflection part attached to the finger part in a state that they are juxtaposed in a movable direction α of the finger part. The reflection part has: a center part facing a light source of the light transmission/reception part; and an annular recess formed on an outer side of the center part. The ECU detects a force in the movable direction α applied to the finger part according to a detection value of a distance between the light transmission/reception part and the reflection part, and in addition, detects a force in a finger axis direction β applied to the finger part based on whether a detection value of a distance is changed discontinuously or not (a reflection position of a detection light on a reflection surface is changed from the center part toward the recess or not).

Description

  The present invention relates to a technique for detecting an external force applied to a finger of a robot hand.

  In a robot having an arm, a technique for detecting the deflection (distortion) of the arm using an optical sensor is disclosed in, for example, Japanese Patent Laid-Open No. 5-302817 (Patent Document 1).

JP-A-5-302817

  By the way, when an object is gripped by a robot hand having a plurality of fingers, external forces from various directions are applied to each finger, so it is necessary to appropriately detect these external forces to control the operation of the robot hand. . However, when an external force in a plurality of directions is detected by the optical sensor disclosed in Patent Document 1, it is necessary to provide a plurality of similar optical sensors, and there is a problem that the finger of the robot hand becomes large.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to detect forces in a plurality of directions applied to the fingers of the robot hand while avoiding an increase in the size of the robot hand. .

  The robot hand according to the present invention includes a finger portion. The robot hand includes a pair of a light transmitting / receiving unit and a reflecting unit that are arranged in the first direction and attached to the finger unit, and is capable of detecting a distance between the light transmitting / receiving unit and the reflecting unit, and an optical sensor A detecting unit that detects a force in the first direction applied to the finger unit based on a detection distance between the light transmitting / receiving unit and the reflecting unit. The reflection part has a central part facing the light source of the light transmitting / receiving part, and an annular part formed in an annular shape outside the central part. In addition to detecting the force in the first direction applied to the finger portion, the detection unit detects a force in the second direction different from the first direction applied to the finger portion based on whether or not reflection at the annular portion is detected. Is detected.

  Preferably, the annular portion includes a step portion having a step with respect to the center portion. The detection unit determines that the force in the second direction has exceeded a predetermined value when the detection distance changes discretely due to reflection at the stepped portion.

  Preferably, the annular portion includes a color changing portion having a different color with respect to the central portion. The detection unit determines that the force in the second direction has exceeded a predetermined value when the intensity or wavelength of light received by the light transmitting / receiving unit is discretely changed due to reflection at the color changing unit.

  Preferably, the annular portion includes a first region having a step or a different color with respect to the central portion, and a second region having a step or a different color with respect to the central portion and the first region. The detection unit determines that a force in the direction connecting the central portion and the first region has occurred when the light receiving state of the light transmitting / receiving unit changes from a state corresponding to the central portion to a state corresponding to the first region. When the light receiving state of the portion changes from the state corresponding to the central portion to the state corresponding to the second region, it is determined that a force in the direction connecting the central portion and the second region has occurred.

Preferably, a plurality of annular portions are provided concentrically at predetermined intervals.
Preferably, the first direction is a direction along the rotation direction of the finger portion. The second direction is a direction along the longitudinal axis of the finger portion.

According to the present invention, it is possible to detect the force in the first direction and the force in the second direction applied to the finger portion by attaching one optical sensor portion to the finger portion. Therefore, it is possible to detect forces in a plurality of directions applied to the fingers of the robot hand while avoiding an increase in the size of the robot hand.
Can do.

It is a figure which shows the structure of a robot hand typically. It is a figure which shows the structure of an optical sensor typically. It is the figure which looked at the reflective surface of the reflection part from the light transmission / reception part side. It is a figure for demonstrating the method to detect the force of the movable direction (alpha) of a finger part. It is a figure for demonstrating the method of detecting the force of the finger | toe finger direction (beta). It is FIG. (1) which shows the modification of the reflective surface of a reflection part. It is FIG. (2) which shows the modification of the reflective surface of a reflection part. It is a figure which shows the modification of an optical sensor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram schematically showing a configuration of a robot hand 1 according to the present embodiment. Note that the configuration of the robot hand 1 shown in FIG. 1 is merely an example, and the present invention is not limited to this.

  The robot hand 1 includes a hand unit 10 for gripping the object 2 and an arm unit 40 for moving and supporting the hand unit 10 to a position where the hand unit 10 can grip the object 2.

  The hand part 10 includes two finger parts 20 and a base part 30 to which the two finger parts 20 are fixed at a predetermined distance. The base part 30 is supported by the arm part 40.

  Each finger portion 20 includes a fingertip portion 21, a joint portion 22, and a finger base portion 23. One end of the finger base part 23 is connected to the base part 30, and the other end of the finger base part 23 is connected to the fingertip part 21 via the joint part 22.

  The joint portion 22 is provided between the fingertip portion 21 and the fingertip portion 23, and the fingertip portion 21 is movable with respect to the fingertip portion 23 in a movable direction α (a direction substantially orthogonal to the longitudinal axis of the fingertip portion 23. ) Is supported to be rotatable. The joint portion 22 includes an actuator (for example, an ultrasonic motor) for rotating the fingertip portion 21 in the movable direction α. A joint part similar to the joint part 22 may be provided between the finger base part 23 and the base part 30 so that the finger base part 23 can be rotated with respect to the base part 30.

  When attempting to grip the object 2 using the robot hand 1, first, the hand unit 10 is moved to a position where the object 2 can be gripped, and then the hand unit 10 is lowered toward the object 2. The arm part 40 is driven. Thereafter, the actuator of the joint portion 22 of each finger portion 20 is driven so as to grip the object 2 by rotating the fingertip portion 21 in the movable direction α.

  At this time, in order to prevent the object 2 from being dropped or damaged, the force with which the fingertip portion 21 grips the object 2 in the movable direction α (hereinafter also simply referred to as “force in the movable direction α”). ) Is desirable.

  Further, when the hand part 10 is moved toward the object 2 and the fingertip part 21 collides with an obstacle, the finger part 20 has, for example, a fingering direction β (the axial center of the finger base part 23 in the longitudinal direction). (Direction along). Thus, there is a possibility that the finger part 20 may be damaged by applying a large force in the finger direction β. Therefore, it is desirable to detect the force in the fingering direction β in addition to the force in the movable direction α (the gripping force of the object 2).

  However, if the sensor for detecting the force in the movable direction α and the sensor for detecting the force in the fingering direction β are provided separately on the finger part 20, the finger part 20 becomes large. That is, there is a concern that the entire length of the finger part 20 becomes long or the width of the finger part 20 becomes thick, and the small object 2 cannot be gripped. In addition, a large number of wires are provided in the vicinity of the movable part, which may hinder the smooth operation of the finger part 20.

  Therefore, in the present embodiment, one optical sensor 60 is attached to one finger 20, and the force in the movable direction α and the force in the finger direction β are separately detected based on the output of the one optical sensor 60. To do.

  One optical sensor 60 is attached to each finger 20. In the present embodiment, the optical sensor 60 is attached to the base portion of the finger portion 23 (portion close to the connection portion with the base portion 30). This eliminates the need to arrange the optical sensor 60 and wiring around the fingertip portion 21 close to the object 2, thereby avoiding failure and disconnection due to interference with the object 2. The configuration of the optical sensor 60 will be described later.

  An electronic control unit (hereinafter referred to as “ECU”) 100 is electrically connected to the optical sensor 60. Since ECU 100 does not necessarily have to be attached to hand unit 10, ECU 100 is arranged at a position away from hand unit 10 in the present embodiment.

  The ECU 100 detects separately the force in the movable direction α and the force in the finger direction β applied to the finger base 23 based on the output of the optical sensor 60.

  FIG. 2 is a diagram schematically illustrating the configuration of the optical sensor 60. The optical sensor 60 is affixed to the surface (inner peripheral surface or outer peripheral surface) of the base portion of the finger portion 23 by an adhesive sheet 62.

  The optical sensor 60 includes a pair of light transmitting / receiving unit 70 and reflecting unit 80 arranged so as to face each other in the movable direction α, and a casing 61 that houses the light transmitting / receiving unit 70 and the reflecting unit 80.

  The light transmission / reception unit 70 is provided adjacent to the side of the light transmission unit including a light source that emits detection light (for example, infrared light) toward the reflection unit 80, and is reflected by the reflection unit 80. A light receiving unit including a PSD (Position Sensitive Detector) that receives detection light.

  The reflection unit 80 has a planar reflection surface orthogonal to the movable direction α. Detection light emitted from the light source of the light transmitting / receiving unit 70 is reflected by the reflecting surface of the reflecting unit 80. The detection light reflected by the reflecting surface of the reflecting unit 80 is received by the PSD of the light transmitting / receiving unit 70.

  This optical sensor 60 transmits and receives light by utilizing the fact that the light receiving position on the PSD of the light transmitting / receiving unit 70 changes according to the change in the distance between the light source of the light transmitting / receiving unit 70 and the reflecting unit 80 (triangulation method). The distance d between the light transmitting / receiving unit 70 and the reflecting unit 80 can be detected from the light receiving position on the PSD of the unit 70. Since the principle of distance detection by triangulation is well known, detailed description thereof will not be repeated here.

  FIG. 3 is a view of the reflecting surface of the reflecting unit 80 as viewed from the light transmitting / receiving unit 70 side. In a state where the finger portion 23 is not distorted, the positional relationship between the light transmitting / receiving unit 70 and the reflecting unit 80 is adjusted so that the detection light from the light transmitting / receiving unit 70 is applied to the center point 81 of the reflecting surface. ing.

  The reflecting surface has a planar center portion including a center point 81 facing the light source of the light transmitting / receiving unit 70, and an annular recess 82 provided outside the center portion. The recess 82 is recessed by a predetermined distance with respect to the plane of the central portion. By providing such a step due to the concave portion 82 outside the central portion, the detection value of the distance d is changed discretely (discontinuously) when the reflection position of the detection light changes from the central portion to the concave portion 82. be able to.

  FIG. 4 is a diagram for explaining a method in which the ECU 100 detects the force in the movable direction α using the output of the optical sensor 60.

  For example, it is assumed that the object 2 is gripped by rotating the fingertip portion 21. In this case, the fingertip portion 23 is distorted in the movable direction α due to the reaction force received from the subject 2 by the fingertip portion 21 that is in contact with the subject 2. Due to this distortion, the casing 61 of the optical sensor 60 is also distorted in the movable direction α (the case where compression is illustrated in FIG. 4), and the distance d between the light transmitting / receiving unit 70 and the reflecting unit 80 changes.

  Using this point, the ECU 100 detects the force in the movable direction α according to the detected value of the distance d. Since this distortion changes continuously with the passage of time to apply the gripping force to the object 2, the distance d also changes continuously with the passage of time as shown in FIG. Further, in the state where the object 2 is gripped by the fingertip portion 21, the force in the fingering direction β hardly acts, so that the distortion in the fingering direction β hardly occurs.

  FIG. 5 is a diagram for describing a method in which the ECU 100 detects the force in the finger direction β using the output of the optical sensor 60.

  For example, it is assumed that the arm part 40 pushes the hand part 10 in the finger direction β while the fingertip part 21 is in contact with the obstacle 3. In this case, the finger portion 23 is distorted in the finger direction β due to the reaction force received from the obstacle 3. Due to this distortion, the housing 61 of the optical sensor 60 is also distorted in the fingering direction β, so that the reflection position of the detection light on the reflecting surface of the reflecting portion 80 is shifted from the center point 81 in the fingering direction β. Then, when the distortion in the finger direction β is large and the reflection position changes from the central portion of the reflection surface to the recess 82, the detected value of the distance d is discontinuously due to the step (dent) of the recess 82, as shown in FIG. Will change (increase).

  Using this point, the ECU 100 detects the force in the finger direction β based on whether or not the detected value of the distance d has changed discontinuously (the amount of change per unit time has exceeded a threshold value). . Specifically, the ECU 100 determines the reflection at the concave portion 82 based on whether or not the detected value of the distance d has changed discontinuously, and when the detected value of the distance d has changed discontinuously, the finger direction β Is detected to have exceeded an allowable value (a force within a range where the finger portion 20 is not damaged). When the detected value of distance d is continuously changing (when the amount of change per unit time is less than the threshold value), ECU 100 detects that the force in fingertip direction β is less than the allowable value.

  Actually, the distortion in the movable direction α and the distortion in the finger direction β are combined. The ECU 100 determines that the force in the fingering direction β is less than the allowable value when the detected value of the distance d continuously changes, and applies the force in the movable direction α according to the detected value of the distance d. To detect. On the other hand, when the detected value of the distance d changes discontinuously, the ECU 100 determines that the force in the fingering direction β exceeds the allowable value and stops the operation of the finger unit 20 or in the fingering direction β. The joint portion 22 or the arm portion 40 is driven so that the force is less than the allowable value.

  As described above, the robot hand 1 according to the present embodiment includes the optical sensor 60 that can detect the distance d between the pair of light transmitting / receiving units 70 and the reflecting unit 80 that are arranged in the movable direction α and attached to the finger unit 20. ECU 100 electrically connected to optical sensor 60. The reflection unit 80 has a central portion facing the light source of the light transmitting / receiving unit 70 and an annular recess 82 formed outside the central portion. In addition to detecting the force in the movable direction α in accordance with the detected value of the distance d between the light transmitting / receiving unit 70 and the reflecting unit 80, the ECU 100 determines whether or not the detected value of the distance d has changed discretely (reflection). Based on whether or not the reflection position of the detection light on the surface has changed from the central portion to the recess 82), it is detected whether or not the force in the finger direction β has exceeded an allowable value. Thereby, even if there is one optical sensor attached to the finger part 20, forces in a plurality of directions (force in the movable direction α and force in the fingering direction β) applied to the finger part 20 can be detected separately. Therefore, it is possible to detect forces in a plurality of directions applied to the finger unit 20 while avoiding an increase in the size of the robot hand 1 (while realizing space saving around the finger unit 20).

<Modification of Reflective Surface of Reflector 80>
In the present embodiment, the concave portion 82 that is recessed from the center portion is provided outside the center portion of the reflecting surface of the reflecting portion 80. However, the configuration provided outside the center portion may be a configuration in which the light receiving state by the light transmitting / receiving unit 70 changes discretely when the reflection position on the reflection surface changes from the center portion to the outside of the center portion. It is not limited to the recess 82.

  For example, instead of the concave portion 82, a convex portion protruding a predetermined distance from the central portion may be provided in the annular portion outside the central portion. Even in this case, when the reflection position changes from the central portion to the outside of the central portion, the detection value of the distance d can be discretely changed by the step (protrusion) of the convex portion.

  Further, a discoloration portion having a color different from that of the central portion may be provided in the annular portion outside the central portion, instead of the concave portion 82. In this way, it is possible to discretely change the intensity or wavelength of the detection light received by the light transmitting / receiving unit 70 when the reflection position changes from the central portion to the outside of the central portion. Therefore, the ECU 100 can detect that the force in the finger direction β exceeds the allowable value by detecting that the intensity or wavelength of the detection light received by the light transmitting / receiving unit 70 has changed discretely.

  Further, the annular portion outside the central portion may be divided into a plurality of regions, and at least one of a step, a color, a step, and a combination of colors may be made different in each region. For example, as shown in FIG. 6, a first region where a concave portion 82 having a step which is the same color as the central portion but has a step is formed in the annular portion outside the central portion, and the step is different from the central portion. A reflecting portion 80A provided with a second region that is not provided but is formed with a color changing portion 83 having a different color may be employed. If it does in this way, the direction of action of force can be detected more correctly. That is, when the detected value of the distance d changes discretely, the ECU 100 detects that a force in the direction connecting the central portion and the first region has occurred, and the intensity or wavelength of the detection light changes discretely It can be detected that a force in the direction connecting the central portion and the second region has occurred.

  Moreover, you may make it provide the several annular part which has a level | step difference or a different color with respect to a center part on the outer side of a center part at predetermined intervals concentrically. For example, as shown in FIG. 7, a reflective portion 80 </ b> B in which a concave portion 84 is further provided inside the concave portion 82 at a predetermined interval concentrically may be adopted. In this way, it is possible to detect the magnitude of the force in the fingering direction β according to the number of times the detection value of the distance d is discretely changed. If at least one of the level difference, the color, the level difference, and the combination of colors is made different in each annular portion, the magnitude of the force in the fingering direction β can be detected more accurately.

<Modified Example of Optical Sensor 60>
Instead of the optical sensor 60 according to the present embodiment, an optical sensor 60A shown in FIG. 8 may be adopted.

  An optical sensor 60 </ b> A illustrated in FIG. 8 is obtained by adding a light receiving unit 90 that receives detection light to the back surface of the reflecting unit 80 with respect to the optical sensor 60. In this way, by providing the light receiving unit 90 not only inside the light transmitting / receiving unit 70 but also on the back surface of the reflecting unit 80, the force in the finger direction β is based on the light receiving position or the amount of light received through the reflecting unit 80. Can be detected.

<Other variations>
In the present embodiment, the number of finger portions 20 is two, but the number of finger portions is not limited to this. That is, the number of finger portions may be three or more, or may be one. Further, in the robot hand 1 illustrated in FIG. 1, the number of joint portions 22 of the finger portion 20 (the number of degrees of freedom of the finger portion 20) is one, but the number of joint portions of the finger portion is not limited to this. . That is, the number of joint portions of the finger portion may be two or more.

  Moreover, in this Embodiment, although the optical sensor 60 was affixed on the fingertip part 23 with the sticking sheet 62, the method of attaching the optical sensor 60 to the fingertip part 23 is not limited to this. For example, you may make it fix to the fingertip part 23 with a volt | bolt etc.

  In the present embodiment, the optical sensor 60 is covered with the housing 61, but the housing 61 may be omitted and the light transmitting / receiving unit 70 and the reflecting unit 80 may be directly attached to the fingertip unit 23.

  In the present embodiment, the optical sensor 60 is attached to the fingertip portion 23, but the attachment position of the optical sensor 60 is not limited to the fingertip portion 23. For example, the optical sensor 60 may be attached to the fingertip portion 21.

  Further, in the present embodiment, ECU 100 is arranged at a position away from hand unit 10, but ECU 100 may be attached to any part of hand unit 10.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 robot hand, 2 object, 3 obstacle, 10 hand part, 20 finger part, 21 fingertip part, 22 joint part, 23 finger base part, 30 base part, 40 arm part, 60 optical sensor, 61 housing, 62 Pasting sheet, 70 Transmitting / receiving unit, 80, 80A, 80B Reflecting unit, 81 Center point, 82, 84 Concavity, 83 Discoloring unit, 90 Light receiving unit, 100 ECU.

Claims (6)

A robot hand with fingers,
An optical sensor unit configured to include a pair of light transmitting / receiving units and a reflecting unit attached to the finger unit in a first direction, and capable of detecting a distance between the light transmitting / receiving unit and the reflecting unit;
A detection unit that detects a force in the first direction applied to the finger unit based on a detection distance between the light transmission / reception unit and the reflection unit of the optical sensor unit;
The reflecting portion has a central portion facing the light source of the light transmitting / receiving portion, and an annular portion formed in an annular shape outside the central portion,
In addition to detecting the force in the first direction applied to the finger unit, the detection unit is configured to determine the first direction applied to the finger unit based on whether or not reflection at the annular portion is detected. A robot hand that detects forces in different second directions. The annular portion includes a step portion having a step with respect to the central portion,
The robot hand according to claim 1, wherein the detection unit determines that the force in the second direction has exceeded a predetermined value when the detection distance changes discretely due to reflection at the stepped portion. The annular portion includes a color changing portion having a different color with respect to the central portion,
The detection unit determines that the force in the second direction has exceeded a predetermined value when the intensity or wavelength of light received by the light transmitting / receiving unit is discretely changed by reflection at the color changing unit. The robot hand described in 1. The annular portion includes a first region having a step or a different color with respect to the central portion, and a second region having a step or a different color with respect to the central portion and the first region,
The detection unit generates a force in a direction connecting the central portion and the first region when the light receiving state of the light transmitting / receiving unit changes from a state corresponding to the central portion to a state corresponding to the first region. And when a light receiving state of the light transmitting / receiving unit is changed from a state corresponding to the central portion to a state corresponding to the second region, a force in a direction connecting the central portion and the second region is generated. The robot hand according to claim 1, wherein the determination is made.   The robot hand according to claim 1, wherein a plurality of the annular portions are provided concentrically at predetermined intervals. The first direction is a direction along the rotation direction of the finger part,
The robot hand according to any one of claims 1 to 5, wherein the second direction is a direction along a longitudinal axis of the finger portion.

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