JP2022118419A - robot hand device - Google Patents

Abstract

To provide a robot hand device with a simpler configuration capable of inhibiting an impact given to an object.SOLUTION: A robot hand device 10 includes: a suction portion 22 for holding an object; a movable portion 26 displaced by a reaction force received from the object when the object held by the suction portion is placed on a placement objective place; and a displacement amount detection unit 28 for detecting a displacement amount of the movable portion; and a control unit 14 for controlling the suction unit on the basis of the displacement amount of the movable portion detected by the displacement amount detection unit.SELECTED DRAWING: Figure 1

Description

The present invention relates to a robot hand device.

Demand for robotization is increasing at sites such as factories due to labor shortages and other factors. Along with this, there are increasing opportunities to use so-called pick-and-place systems in which parts are picked and then placed by a robot. In recent years, the objects grasped by robot hands have become diverse, and among them, there are objects that are vulnerable to impact. When picking and placing an impact-sensitive object with a robot hand, a design that considers the timing of gripping during picking and the timing of releasing during placement is required to reduce the impact on the object during both picking and placing. Ingenuity is required.

In general, when a robot hand such as a multi-fingered robot hand is used to grasp an object of arbitrary shape or from an arbitrary direction, when placing the object on the floor, etc., the object is moved away from the robot hand. It is very difficult to control the timing properly. Therefore, if the release timing is too early, the object will fall to the floor, and if the release timing is too late, the object will be strongly pressed against the floor. In either case, an impact is applied to the object, and there is a risk of damaging the object.

Patent Document 1 describes a control system in which when an object gripped by a robot hand is placed at a predetermined location, the reaction force received from that location is calculated, and when the calculated reaction force exceeds a threshold, the object is released from the robot hand. Techniques for doing so are described. Further, in Patent Document 1, the fingertip resultant force in the coordinate system of the robot hand is changed to the fingertip resultant force in the coordinate system of the base of the robot hand device according to the attitude of the robot hand from the coordinate system of the base of the robot hand device to the coordinate system of the robot hand. Estimate the weight of the object based on the fingertip force in the vertical direction among the fingertip force in the base coordinate system of the robot hand device, and the difference between the estimated weight of the object and the force to grip the object in the robot hand. Based on this, a technique for calculating the reaction force received from the place where the object is placed is described.

JP-A-2007-276112

However, in the technique described in Patent Document 1, a plurality of pieces of input information ( Image signal PS obtained by photographing the object before gripping, joint angle signal AS obtained by detecting the rotation angle of each joint, 6-axis force signal FS for each finger), calculation of release timing is complicated. There was a problem that it was difficult to

SUMMARY OF THE INVENTION An object of the present invention is to provide a robot hand device capable of suppressing impact applied to an object with a simpler configuration.

A robot hand device according to the present invention includes a holding portion that holds an object, a movable portion that is displaced by a reaction force received from the object when the object held by the holding portion is placed in a place, and a displacement amount of the movable portion that is detected. and a control unit that controls the holding unit based on the displacement amount of the movable portion detected by the displacement amount detection unit.

ADVANTAGE OF THE INVENTION According to this invention, the impact given to an object can be suppressed by a simpler structure.

1 is a side view showing a configuration example of a robot hand device according to an embodiment of the present invention; FIG. It is the schematic side view which expanded the A section of FIG. 4 is a flow chart showing an operation procedure of the robot hand device according to the embodiment of the present invention; FIG. 11 is a schematic side view showing a state in which the suction unit is pressed against a picking location; It is a schematic side view which shows the state which pressed the adsorption|suction part to the object. 4 is a flow chart showing a method of setting a release threshold;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification and the drawings, elements having substantially the same function or configuration are denoted by the same reference numerals, and overlapping descriptions are omitted.

<Configuration of robot hand device>
FIG. 1 is a side view showing a configuration example of a robot hand device according to an embodiment of the present invention, and FIG. 2 is a schematic side view enlarging part A of FIG.
As shown in FIGS. 1 and 2 , the robot hand device 10 includes a robot hand section 12 and a control section 14 that controls the operation of the robot hand section 12 .

The robot hand unit 12 is used to transfer an object (not shown) from a pick place to a place place by pick & place. A pick location is a location for picking objects, i.e., a location from which objects are transferred. A place position is a place for placing an object, that is, a place to which the object is to be transferred. The robot hand unit 12 is attached to a robot arm (not shown) and moves according to the motion of the robot arm.

The robot hand section 12 includes a hand main body section 20 which is a main body portion of the robot hand section 12, a suction section 22 which holds an object (not shown) by air suction, and a grasping section 24 which grasps an object, and is movable in a predetermined direction. a movable portion 26 and a displacement amount detection portion 28 for detecting the amount of displacement of the movable portion 26 . The adsorption section 22 is provided as an example of a holding section.

The hand body portion 20 has a drive mechanism for operating the grip portion 24 . The adsorption part 22 is attached to the bracket 30 . The bracket 30 is attached to the hand body portion 20 . The adsorption portion 22 is preferably configured by an elastic member exhibiting rubber-like elasticity. The adsorption part 22 has an air flow path (not shown) for holding an object by air adsorption. A terminal end of the air flow path opens downward at the lower end of the adsorption section 22 . On the other hand, the starting end of the air flow path is connected to an air circuit (not shown). The air circuit is configured using an air tube, an air control valve, and the like. The air circuit sucks air through the air flow path when an object is held by the suction section 22 . Further, the air circuit stops sucking air when releasing the object held by the sucking section 22 . The operation of the air circuit is controlled by the controller 14 . In the following description, the state in which air is sucked by the air circuit is the ON state, and the state in which the air suction is stopped is the OFF state.

The grip portion 24 is attached to the hand body portion 20 . As shown in FIG. 1, the grips 24 are arranged in pairs on the left and right. The gripping portion 24 includes a link mechanism portion 241 and a gripper portion 242 . The link mechanism part 241 opens and closes the left and right gripper parts 242 by operating in the direction B in FIG. The gripper portion 242 is a portion that grips an object (not shown) so as to sandwich it from both sides. The gripper portion 242 has a concave portion 242a that contacts an object (not shown) when gripping the object. The gripping portion 24 positions the object by gripping the object with a pair of gripper portions 242 .

The movable portion 26 is displaced by a reaction force received from the object when the object held by the suction portion 22 is placed on the place. The direction in which the movable portion 26 is displaced is the same direction as the direction of the reaction force received from the object. In the present embodiment, when an object held by the adsorption section 22 is placed on the place, the direction of the reaction force received by the adsorption section 22 and the movable section 26 from the object and the direction in which the movable section 26 is displaced are both upward. direction.

The movable portion 26 includes a slide rod 261 and a spring member 262 that biases the slide rod 261, as shown in FIG. The slide rod 261 is provided as an example of a slide member, and the spring member 262 is provided as an example of an elastic body.

The slide rod 261 has a large diameter rod portion 261a and a small diameter rod portion 261b. The large-diameter rod portion 261a and the small-diameter rod portion 261b may have an integral structure, or may have a structure connected by screws. The slide rod 261 is arranged with the large-diameter rod portion 261a facing downward. The adsorption portion 22 is fixed to the lower surface of the large-diameter rod portion 261a. The small-diameter rod portion 261b is supported by a slide guide member 263 so as to be vertically slidable (movable). The slide guide member 263 is fixed to the base member 32 . The base member 32 is a member attached to the lower end portion of the bracket 30 in order to support the adsorption portion 22 , the movable portion 26 and the displacement amount detection portion 28 .

The spring member 262 is attached to the small diameter rod portion 261 b of the slide rod 261 . The spring member 262 is composed of a coil spring. The spring member 262 is arranged in a compressed state between the large-diameter rod portion 261 a and the slide guide member 263 . A reaction force due to the compression of the spring member 262 acts as an urging force that urges the slide rod 261 and the adsorption portion 22 downward. A retainer (not shown) is attached to the upper end of the small-diameter rod portion 261b. The retaining stopper abuts against the upper surface of the slide guide member 263 so that the small-diameter rod portion 261 b of the slide rod 261 does not come off from the slide guide member 263 .

The displacement amount detection unit 28 detects the amount of displacement of the slide rod 261 which is one component of the movable unit 26 . The displacement amount detection unit 28 is configured by, for example, a displacement sensor. The displacement sensor outputs an analog sensor signal corresponding to the amount of displacement of the slide rod 261 . The sensor signal output by the displacement detection unit 28 is an electric signal in which the value of current, voltage, resistance, or the like changes according to the amount of displacement of the slide rod 261 . This electrical signal is taken into the control unit 14 . The control unit 14 obtains a detection value indicating the amount of displacement of the slide rod 261 by A/D (analog/digital) converting the electrical signal received from the displacement amount detection unit 28 .

The control section 14 controls the suction section 22 based on the displacement amount of the movable section 26 detected by the displacement amount detection section 28 . Specifically, the control unit 14 controls the adsorption unit 22 by switching the on/off state of the air adsorption by the air circuit described above. When the air suction by the air circuit is switched from the OFF state to the ON state, the suction force due to the air suction is generated in the suction portion 22 . Therefore, the object 35 can be held by causing the object 35 to be attracted to the lower end portion of the attraction portion 22 . On the other hand, when the air suction by the air circuit is switched from the ON state to the OFF state, the suction force due to the air suction disappears. Therefore, it becomes possible to release the object 35 . Further, the control unit 14 controls the operation of the grasping unit 24 by driving the driving mechanism of the hand body unit 20 . In this embodiment, the control unit 14 controls both the motion of the robot hand device 10 and the motion of the robot arm.

<Operation of robot hand device>
Next, the operation of the robot hand device 10 according to the embodiment of the present invention will be explained using the flowchart of FIG.

First, the control unit 14 moves the robot hand unit 12 directly above the picking place by the operation of the robot arm (step S1).

Next, the control section 14 opens the grip section 24 by driving the drive mechanism (step S2). When the grip portion 24 is opened, the pair of gripper portions 242 move away from each other according to the operation of the pair of link mechanism portions 241 . When the gripping portion 24 is opened as described above, the suction portion 22 is arranged to protrude below the gripper portion 242 . Thereby, the adsorption part 22 can be brought into contact with the object without bringing the grip part 24 into contact with the object. Also, as shown in FIG. 4, by pressing the suction unit 22 against the picking place 33, it is possible to confirm in advance whether the displacement detection unit 28 operates normally. Note that if the gripping portion 24 has already been opened at the stage of step S1, the process of step S2 may be omitted.

Next, the control unit 14 vertically lowers the robot hand unit 12 by operating the robot arm (step S3). As a result, as shown in FIG. 2, when an object 35 is placed at the picking place 33, the suction unit 22 gradually approaches the object 35 as the robot hand unit 12 descends. Then, when the suction unit 22 contacts the object 35, the control unit 14 temporarily stops the lowering of the robot hand unit 12 (step S4), and then closes the gripping unit 24 by driving the drive mechanism (step S5). . When the gripping portion 24 is closed, the pair of gripper portions 242 move toward each other according to the operation of the pair of link mechanism portions 241 . Thereby, the object 35 is gripped by the pair of gripper portions 242 and positioned at a predetermined position. The timing at which the lowering of the robot hand portion 12 is temporarily stopped may be the timing at which the movable portion 26 begins to be displaced due to contact between the suction portion 22 and the object 35 .

Next, as shown in FIG. 5, the control unit 14 presses the adsorption unit 22 against the object 35 by restarting the descent of the robot hand unit 12 by the operation of the robot arm (step S6). As a result, the adsorption portion 22 is compressed and deformed by the reaction force received from the object 35 , and the movable portion 26 is displaced upward by the reaction force received from the object 35 . The displacement of the movable portion 26 described here occurs when the spring member 262 is pushed by the reaction force received from the object 35 and compressed, thereby causing the slide rod 261 to move upward while being guided by the slide guide member 263 .

Next, the control section 14 determines whether or not the displacement amount of the movable section 26 detected by the displacement amount detection section 28 exceeds the holding threshold (step S7). At this time, if the displacement amount of the movable part 26 does not exceed the holding threshold value, the control unit 14 continues the descent of the robot hand part 12, and if the displacement amount of the movable part 26 exceeds the holding threshold value, , the lowering of the robot hand unit 12 is stopped (step S8). The holding threshold is a preset threshold for controlling the operation of the robot hand unit 12 . The retention threshold is preferably set according to the hardness of the pick location. For example, if the pick location is a hard location formed by metal, hard plastic, etc., the retention threshold is set to a small value, and if the pick location is a soft location formed by sponge, rubber, etc., the retention threshold is set to is set to a large value.

Next, the control unit 14 causes the suction unit 22 to hold the object 35 by sucking air from the air flow path of the suction unit 22 by operating the air circuit (step S9). As a result, the object 35 is held by the suction section 22 while being positioned by the grip section 24 .

Next, the control unit 14 drives the drive mechanism to open the grasping unit 24 (step S10), and then vertically raises the robot hand unit 12 by operating the robot arm (step S11).

Next, the control unit 14 moves the robot hand unit 12 directly above the place by the operation of the robot arm (step S12).

Next, the control unit 14 vertically lowers the robot hand unit 12 by operating the robot arm (step S13). As a result, the object 35 held by the suction portion 22 gradually approaches the place. Then, when the object 35 comes into contact with the place place, the adsorption portion 22 is compressed and deformed by the reaction force received from the object 35, and the movable portion 26 is displaced upward. The state of the robot hand unit 12 at this time is basically the same as the state shown in FIG. 5 except that the picking place 33 is changed to the place place.

Next, the control section 14 determines whether or not the displacement amount of the movable section 26 detected by the displacement amount detection section 28 exceeds the release threshold (step S14). At this time, if the amount of displacement of the movable part 26 does not exceed the threshold for release, the control unit 14 continues the descent of the robot hand part 12, and if the amount of displacement of the movable part 26 exceeds the threshold for release, , the lowering of the robot hand unit 12 is stopped (step S15). The release threshold is a preset threshold for controlling the operation of the robot hand unit 12 . The release threshold is preferably set according to the hardness of the place of placement. For example, if the place is a hard place made of metal, hard plastic, etc., the release threshold is set to a small value, and if the place is a soft place made of sponge, rubber, etc., the release threshold is set to is set to a large value. Note that the threshold for release and the threshold for retention may be the same value or different values.

Next, the control unit 14 releases the object 35 by stopping the air suction of the suction unit 22 by operating the air circuit (step S16). At this time, in order to increase the positional accuracy of the object 35 placed on the place, the control unit 14 may sequentially perform the closing operation and the opening operation of the gripping unit 24 by driving the drive mechanism.

Next, the control unit 14 vertically raises the robot hand unit 12 by operating the robot arm (step S17). As a result, the robot hand unit 12 retreats from the place.

After that, the control unit 14 confirms whether or not all the scheduled objects 35 have been transferred (step S18). If the next object 35 to be transferred remains at the picking location, the control unit 14 returns to the process of step S1, and if all the objects 35 have been transferred, the series of operations is terminated. . The confirmation in step S16 may be performed by counting the number of objects 35 transferred from the picking place to the placing place by the control unit 14 and determining whether or not the count value reaches a predetermined value. The predetermined value is set to the number of objects scheduled to be transferred.

<Threshold setting method>
Next, a method for setting the release threshold will be described with reference to FIG. Note that the method for setting the hold threshold is basically the same as the method for setting the release threshold, so description thereof will be omitted.

First, the hardness of the object is measured using a hardness measuring device (not shown) (step S31). The hardness measurement of an object may be carried out by either one of the indentation test method and the dynamic test method. Measurement values obtained by the indentation test method are Brinell hardness, Vickers hardness, Rockwell hardness, etc., and measurement values obtained by the dynamic test method are Shore hardness, Knoop hardness, and the like.

Next, the hardness of the place is measured using the hardness measuring instrument (step S32). The hardness measurement of the place may be performed in the same manner as the hardness measurement of the object described above.

Next, a release threshold is set based on the hardness of the object obtained by the measurement in step S31 and the hardness of the place location obtained by the measurement in step S32 (step S33). For example, the release threshold may be set as follows.
First, the hardness of the object and the hardness of the place place are added, and the value of the hardness which is 1/2 of the added value is obtained. On the other hand, table data in which a plurality of thresholds and a plurality of hardnesses are associated with each other is prepared in advance. Then, the threshold value associated with the hardness value obtained earlier is read from the table data, and the read threshold value is set as the release threshold value.

In this way, by setting the release threshold based on the hardness of the object and the hardness of the placement location, the object can be released at an earlier timing when, for example, handling a soft object or placing the object on a hard placement location. The release threshold can be set as follows: This allows the object to be released before squeezing it into place. Therefore, the impact given to the object can be suppressed. This effect can also be obtained when the holding threshold value is set by a method similar to that described above.

In this embodiment, the hardness of the place is measured after the hardness of the object is measured. Conversely, the hardness of the object is measured after the hardness of the place is measured. good too.

Further, in the present embodiment, the threshold for release is set based on the hardness of the object and the hardness of the placement location, but the present invention is not limited to this, and the threshold for release is set based only on the hardness of the object. Alternatively, the release threshold may be set based only on the hardness of the place.

Also, when setting the holding threshold, instead of measuring the hardness of the place location, the hardness of the pick location may be measured.

Also, the retention threshold is preferably set based on the amount of bulk objects at the pick location. Randomly piled amount means the amount when a plurality of objects are piled up in a random state. When the amount of randomly piled objects increases, when one of the plurality of randomly piled objects is held by the suction unit 22, the object tends to collapse due to the pushing of the suction unit 22.例文帳に追加For this reason, when the amount of randomly piled objects is large, it is possible to suppress collapse of the objects by setting the holding threshold to a small value.

<Effects of Embodiment>
As described above, in the robot hand device 10 according to the embodiment of the present invention, when the object 35 held by the suction unit 22 is placed on the place, the reaction force received from the object 35 displaces the movable unit 26 and displaces the movable unit 26. , the displacement amount of the movable portion 26 is detected by the displacement amount detection portion 28 . The control unit 14 controls the suction unit 22 based on the displacement amount of the movable unit 26 detected by the displacement amount detection unit 28 . Thereby, the object 35 held by the adsorption part 22 can be released at an appropriate timing. Also, the release timing of the object 35 can be set with a simpler configuration than the conventional one. As a result, the impact applied to the object 35 can be suppressed with a simpler configuration. Also, it is possible to realize a robot hand device capable of safely picking and placing various objects in various places with a simple configuration.

Further, in this embodiment, the movable portion 26 is configured to be displaced in the same direction as the direction of the reaction force received from the object 35 . As a result, the amount of displacement of the movable portion 26 becomes a value that directly reflects the reaction force received from the object 35 placed at the place. Therefore, the release timing can be set with a simpler configuration.

<Modifications, etc.>
The technical scope of the present invention is not limited to the above-described embodiments, but also includes forms with various modifications and improvements within the range where specific effects obtained by the constituent elements of the invention and their combinations can be derived.

For example, in the above-described embodiment, the suction unit 22 is used as an example of the holding unit, and the case where the suction unit 22 holds the object 35 by air suction is described. However, the present invention is not limited to this. An object may be held by an electromagnet. Alternatively, the grip portion 24 may also have a function of the holding portion.

DESCRIPTION OF SYMBOLS 10... Robot hand apparatus 14... Control part 22... Adsorption part (holding part)
24... Grasping part 26... Movable part 28... Displacement detection part 35... Object

Claims (10)

a holding unit that holds an object;
a movable portion that is displaced by a reaction force received from the object when the object held by the holding portion is placed on the place;
a displacement amount detection unit that detects the amount of displacement of the movable part;
a control unit that controls the holding unit based on the displacement amount of the movable unit detected by the displacement amount detection unit;
A robot hand device comprising: The robot hand device according to claim 1, wherein the movable portion is displaced in the same direction as the direction of reaction force received from the object. When the object held by the holding unit is placed on the place, the control unit releases the object when the amount of displacement of the movable unit detected by the displacement amount detection unit exceeds a release threshold. The robot hand device according to claim 1 or 2, wherein the holding section is controlled so as to When the holding unit holds an object placed at a picking location, the control unit holds the object when the displacement amount of the movable unit detected by the displacement amount detection unit exceeds a holding threshold. The robot hand device according to any one of claims 1 to 3, wherein the holding section is controlled so as to The robot hand device according to claim 3, wherein the release threshold is set based on hardness of the place. The robot hand device according to claim 3, wherein the release threshold is set based on hardness of the object. The robot hand device according to claim 4, wherein the holding threshold is set based on the hardness of the pick location. The robot hand device according to claim 4, wherein the holding threshold is set based on hardness of the object. 5. The robot hand device according to claim 4, wherein the holding threshold is set based on the amount of the objects randomly piled at the picking location. The robot hand device according to any one of claims 1 to 9, further comprising a grasping part that positions the object by grasping the object.

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