JP2012250334A - Robot, and method for controlling robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily determine whether an object is acceptable or not even when a hand part is exchanged.SOLUTION: The hand part stores hand information on the weight of the hand part. Upon detecting a load to be received by an arm portion from the hand part gripping an object, a load component caused by the object out of that load is determined based on the hand information, and whether the object is acceptable or not is determined based on the obtained load of the object. Accordingly, the hand information is automatically updated upon exchanging the hand part, thus, whether the object is acceptable or not can be accurately determined by extracting the load caused by the hand part from the total load acting on the arm portion.

Description

The present invention relates to a robot that grips an object using a hand unit that is detachably provided at the tip of an arm unit, and a method for controlling the robot.

Advances in robot technology have led to the use of robots in various processes at the manufacturing site. For example, painting robots and welding robots are widely used in processes such as painting and welding. Also, in recent years, so-called compliance control technology has advanced and it has become possible to grip the object with an appropriate force so as not to break the object, and as a result, robots will be used for parts transportation and parts assembly. It has become. Of course, it is difficult to grab any object like a human hand at present, but it is possible to grasp most objects by replacing the part (hand part) that grasps the object. It is.

Further, in the robot that grips the target object in this way, since the entire weight of the gripped target object is applied to the arm part of the robot, the weight of the target object can be detected by detecting the load applied to the arm part. . Therefore, a technique has been proposed in which a sensor (so-called load cell) for detecting a load is mounted on the arm portion and the quality of the object is determined based on whether or not the detected load is within an appropriate range (patent) Reference 1).

JP 2001-310284 A

However, since the weight of the object and the hand part is actually detected in the proposed technique, the detected load value changes when the hand part is replaced. There was a problem that it was impossible to accurately determine the quality of the product. Of course, this problem can be avoided by changing the reference value for judging pass / fail every time the hand part is replaced, but it is cumbersome to change the reference value every time the hand part is replaced. .

The present invention has been made to solve at least a part of the above-described problems of the conventional technology, and provides a technology capable of accurately and easily determining the quality of a grasped object. For the purpose.

In order to solve at least a part of the problems described above, the robot of the present invention employs the following configuration. That is,
A robot comprising: an arm unit; a hand unit that is detachably attached to a tip of the arm unit; and a control unit that controls an operation of the arm unit and the hand unit;
The hand part is provided with hand information storage means for storing hand information relating to the weight of the hand part,
The arm part is provided with a load detection means for detecting a load that the arm part receives from the hand part,
In the control unit,
Hand information reading means for reading the hand information from the hand information storage means;
Determining means for determining a component of a load by the object in the detected load based on the detected load and the read hand information;
And a pass / fail judgment means for judging pass / fail of the object based on the determined component of the load by the object.

In the robot of the present invention having such a configuration, information on the weight of the hand unit is stored in the hand unit as hand information. And the load which an arm part receives from the hand part which hold | gripped the target object is detected. The load detected in this way includes a load due to the weight of the object gripped by the hand portion and a load due to the weight of the hand portion. Therefore, the load component due to the object in the detected load is determined based on the hand information read from the hand unit, and the quality of the object is determined based on the obtained load component of the object. .

If it carries out like this, the influence by a hand part can be excluded from the load concerning an arm part, and the component of the load by a target object can be determined. As a result, even when the hand unit is replaced, it is possible to accurately determine the quality of the object. Moreover, since the hand information regarding the weight of the hand unit is stored in the hand information storage means of the hand unit, the hand information is automatically changed when the hand unit is replaced. For this reason, it is possible to accurately and easily determine the quality of the object held by the hand unit.

Further, the above-described robot of the present invention may be configured as follows. First, information relating to the gravity center position of the hand unit is also stored as hand information. In addition, when detecting the load received by the arm unit from the hand unit holding the object, the couple load received by the arm unit is also detected. The couple load detected in this way includes a couple load by the object and a couple load by the hand portion. Moreover, the couple load by a hand part can be calculated | required based on the information regarding the weight of the hand part memorize | stored as hand information, and the gravity center position of a hand part. Therefore, the component of the couple load by the object in the detected couple load is determined based on the hand information read from the hand unit. And the quality of a target object is determined based on the component of the load by a target object, and the component of the couple load by a target object.

In this way, it is possible to determine pass / fail by considering not only the weight of the object but also the position of the center of gravity. For this reason, it is possible to correctly determine the quality of the grasped object even when the weight is accidentally the same even though the shape is different from the correct object. Further, since the position of the center of gravity changes even when the orientation of the grasped object is different or when the object cannot be grasped correctly, it is possible to detect that these situations have occurred. The “center of gravity position information” stored as hand information may be the center of gravity position itself. However, as described above, the center of gravity position of the hand portion is for determining the couple load along with the weight of the hand portion. Used for. Therefore, the value of the couple load that the hand portion exerts on the arm portion may be stored as “information relating to the position of the center of gravity”.

In the above-described robot according to the present invention, when the object is gripped, the arm portion detects the gravitational method or the angle formed with respect to the horizontal direction (based on the gravitational direction), and the detected angle and hand information are used. The quality of the object may be determined by obtaining the component of the couple load by the object based on the above. The angle formed by the arm part with respect to the gravity direction or the horizontal direction may be detected directly by a sensor with a built-in level or the like, but by calculating from control information for controlling the operation of the arm part, It may be detected indirectly.

Depending on the hand unit attached to the arm unit, the angle at which the object is gripped may be different. Alternatively, even when the hand part is not replaced, the gripping angle may vary depending on the object. Even in such a case, if the angle formed by the arm portion with respect to the gravitational direction or the horizontal direction is detected, the couple load due to the object can be detected correctly, so that the quality of the object can be accurately determined. It becomes possible.

The above-described present invention can also be grasped as an invention relating to the following robot control method. That is, the control method of the present invention corresponding to the robot of the present invention is as follows.
A robot control method comprising: an arm unit; and a hand unit that is detachably attached to a tip of the arm unit and grips an object,
A reading step of reading out hand information regarding the weight of the hand unit from the hand unit;
A detection step of detecting a load that the arm portion receives from the hand portion;
A determination step of determining a component of a load by the object in a load received by the arm unit based on a load received by the arm unit and the hand information;
And a determination step of determining pass / fail of the target object based on the determined component of the load by the target object.

If the robot is controlled by such a method, the influence of the hand part can be eliminated from the load received by the arm part, and the component of the load by the object can be determined. Also,
When the hand unit is replaced, the hand information to be read is automatically changed. For this reason, it becomes possible to determine the quality of the object with high accuracy without being affected by the replacement of the hand unit.

Further, the control method of the present invention described above may be as follows. First, when hand information is read from the hand part, information on the center of gravity of the hand part is also read. Moreover, when detecting the load which an arm part receives from a hand part, the couple force load which an arm part receives is also detected. Then, when determining the component of the load by the object in the load received by the arm unit, the component of the couple load by the object is also determined based on the couple load received by the arm unit and the hand information. . You may make it determine the quality of a target object based on the component of the load by the target object determined in this way, and the component of the couple load by a target object.

If the robot is controlled in this way, it is possible to determine whether the object is good or not because it is possible to determine not only the weight of the grasped object but also the position of the center of gravity. It is also possible to detect that the orientation of the gripped object is different and that the object cannot be gripped correctly.

It is explanatory drawing which showed the structure of the robot of a present Example. It is a flowchart of the object determination process which the robot of a present Example determines the quality of a target object. It is explanatory drawing which showed the method in which the robot of a present Example determines the quality of a target object. It is explanatory drawing which showed the modification which determines the quality of a target object. It is explanatory drawing which showed the other aspect of the modification which determines the quality of a target object.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. The structure of the robot of this embodiment:
B. Object judgment processing:
C. Variations:

A. Robot structure of this embodiment:
FIG. 1 is an explanatory diagram showing a rough structure of the robot 100 according to the present embodiment. As shown in FIG. 1A, the robot 100 according to the present embodiment includes a hand unit 110 that holds the object W,
The arm unit 120 supports the hand unit 110 and moves the hand unit 110, and the main body unit 130 supports the arm unit 120. The arm part 120 is provided with a plurality of joints, and the hand part 110 can be moved by bending or rotating the arm part 120 at the joint part. In addition, the main body unit 130 includes a control unit 13.
2, the operation in which the hand unit 110 grips the object W and the operation in which the arm unit 120 moves the hand unit 110 are controlled by the control unit 132. For this reason, for example, the robot 100 can perform an operation of holding the object W at the point A and transporting it to the point B.

Further, a sensor (load cell 122) for detecting a load or a couple load is provided on the distal end side (the side on which the hand unit 110 is attached) of the arm unit 120. When the object W is transported, all the weights of the object W and the hand unit 110 are added to the arm unit 120. Therefore, the weight of the object W and the hand unit 110 is detected by detecting the load with the load cell 122. can do.

Further, in the robot 100 of this embodiment, a memory 112 is mounted on the hand unit 110, and information regarding the weight of the hand unit 110 is stored in the memory 112. For this reason, the weight of the grasped object W can be detected by subtracting the weight of the hand unit 110 stored in the memory 112 from the load detected by the load cell 122. In this embodiment, the load cell 122 corresponds to the “load detection means” in the present invention.

Further, the memory 112 of the present embodiment includes not only the weight of the hand unit 110 but also the hand unit 1.
Ten centroid positions are also stored. For this reason, although mentioned later in detail, the couple load which acts on load cell 122 in the state where hand part 110 is not grasping object W can be calculated. As a result, it is also possible to detect the magnitude of the couple load by the object W by subtracting the couple load by the hand unit 110 from the couple load detected by the load cell 122. In this embodiment, the weight and the center of gravity of the hand unit 110 stored in the memory 112 correspond to “hand information” in the present invention, and the memory 112 corresponds to “hand information storage means” in the present invention. .

Further, the hand part 110 is a tip part of the arm part 120 (the load cell 122 in this embodiment).
It is possible to grip various objects W by replacing the hand unit 110 according to the object W to be gripped. FIG. 1B illustrates how various hand portions 110 a to 110 c are replaced with respect to the arm portion 120.

Moreover, the memory 112 is mounted in these hand parts 110a-110c, and the weight and gravity center position of each hand part 110a-110c are memorize | stored. For this reason, the robot 100 according to the present embodiment can detect the object W even when the hand units 110a to 110c are replaced.
It is possible to determine the quality of the object W by detecting the magnitude of the load or the couple load. Below, the object determination process which the robot 100 of a present Example performs in order to determine the quality of the hold | gripped target object W is demonstrated.

B. Object judgment processing:
FIG. 2 is a flowchart of the object determination process. This process is a process performed by the control unit 132 built in the main body 130 of the robot 100. In the object judgment process,
First, it is determined whether or not the hand unit 110 has been replaced, that is, whether or not the hand unit 110 has been replaced after determining the quality of the object W last time (step S100). This determination can be made by various methods. For example, an identification number unique to the hand unit 110 is stored in the memory 112. And if this identification number is detected and the identification number is changed, it can be determined that the hand unit 110 has been replaced. Alternatively, when the hand unit 110 is detached, a flag is set in the internal memory of the control unit 132. If this flag is set, it can be determined that the hand unit 110 has been replaced. .

As a result, when the hand unit 110 has been replaced (step S100: yes), the hand information is acquired by reading the data stored in the memory 112 of the hand unit 110 (step S102). The hand information may be various information as long as the information includes the weight of the hand unit 110. Here, the hand information is assumed to be the weight of the hand unit 110 and the position of the center of gravity. How to express the center of gravity position of the hand unit 110 will be described later. On the other hand, if the hand unit 110 has not been replaced (step S1
00: no), the process of reading the hand information (step S102) is not performed.

Subsequently, an operation of gripping the object W is performed (step S104). That is, the arm part 1
After the hand unit 110 is moved to the position of the object W by driving 20, the operation of gripping the object W by the hand unit 110 is performed. Since this operation is a general operation, description thereof is omitted. Then, the grasped object W is slowly lifted, and the load and couple load applied to the load cell 122 at that time are detected (step S106).

FIG. 3 is an explanatory diagram of a load and a couple load detected by the load cell 122 when the object W is slowly lifted. FIG. 3A shows the object W and the hand unit 110.
The weight and center of gravity position for is shown. The weight Gw of the object W and the hand part 11
A weight Gt of 0 acts on each center of gravity. Further, here, the hand unit 110 grasps the object W from the side, and the center of gravity position of the object W and the center of gravity of the hand unit 110 are represented by a horizontal distance from the mounting surface of the hand unit 110. . That is, the center of gravity of the object W is at a position Lw from the mounting surface of the hand unit 110, and the center of gravity of the hand unit 110 is at a position Lt. The center of gravity position can also be expressed by the distance from the origin of the load cell 122, but for the sake of convenience of explanation, it is displayed here by the distance from the mounting surface of the hand unit 110.

At this time, the load acting on the load cell 122 and the couple load are shown in FIG.
It is shown in (c). That is, as shown in FIG. 3B, a load (Gw + Gt) obtained by adding the weight Gw of the object W and the weight Gt of the hand unit 110 acts on the load cell 122. Further, considering the attachment surface of the hand part 110 to the load cell 122 as a center, the object W
Is located at a distance of Lw from the 0 attachment surface to the load cell 122, the object W applies a couple load of (Gw · Lw) counterclockwise. Similarly for the hand part 110,
Since the center of gravity of the hand portion 110 is at a distance Lt from the mounting surface to the load cell 122, the hand portion 110 applies a couple load of (Gt · Lt) counterclockwise to the mounting surface to the load cell 122. Let As a result, as shown in FIG. 3C, the couple load of (Gw · Lw + Gt · Lt) acts counterclockwise on the attachment surface of the hand unit 110 to the load cell 122. Eventually, in step S106 of the object determination process shown in FIG. 2, the downward load (Gw + Gt) shown in FIG. 3B and the counterclockwise couple load (Gw) shown in FIG.・
Lw + Gt · Lt) is detected.

Subsequently, by correcting the load and the couple load obtained in the load cell 122 using the hand information previously acquired in step S102, the component by the object W (the load and couple load by the object). ) Is acquired (step S108). As is apparent from FIG. 3B, the load due to the object W can be obtained by subtracting the weight Gt of the hand unit 110 acquired as hand information from the load (Gw + Gt) detected by the load cell 122. Further, as apparent from FIG. 3C, the couple load by the object W is determined from the couple load (Gw · Lw + Gt · Lt) detected by the load cell 122.
(Lt) can be obtained by subtracting, and the couple load by the hand unit 110 is
It can be obtained by multiplying the distance Lt indicating the gravity center position of the hand unit 110 acquired as hand information and the weight Gt of the hand unit 110.

And it is judged whether the load of the target object W calculated in this way exists in the range of an appropriate load (step S110). As a result, when the obtained load is not within the range of the appropriate load (step S110: no), the grasped object W is not correct (for example, the object W is defective in production, or It is determined that the object W is a completely different type of object W (step S116).

On the other hand, if the load of the object W calculated in step S108 is within the range of the appropriate load (step S110: yes), then the couple load by the object W calculated in step S108 is appropriate. It is determined whether it is within the range of a strong couple load (step S112).
As a result, if the calculated couple load does not fall within the appropriate couple load range (step S1).
12: no), it is determined that the grasped object W is not correct (step S116). For example, it is conceivable that the weight of the object W coincides with that of the correct object W, but the position of the center of gravity is different because the shape is not the same. Or although it is the correct target W, when the direction in which the target W is placed is different or the target W is tilted, it is determined that the gripped target W is not correct (step S116).

On the other hand, when the couple load by the object W calculated in step S108 is within the range of the appropriate couple load (step S112: yes), the grasped object W is the correct object W. It is determined that there is an object (step S114), and the object determination process shown in FIG.
In addition, the process which reads the hand information, the process which calculates | requires the load by the target object W from the load detected with the load cell 122, and also the process which determines the quality of the target object W based on the calculated | required load of the target object W are control. This is performed when the unit 132 executes the above-described object determination process. Therefore, the control unit 132 according to the present embodiment performs the “hand information reading unit”, “decision unit”, and “
This corresponds to “good / bad determination means”.

As described above, the robot 100 according to the present embodiment includes the attached hand unit 110.
The weight of the object W is calculated by reading the hand information and correcting the load detected by the load cell 122 using the hand information. For this reason, even when the hand unit 110 is replaced, the weight of the object W can be accurately obtained, so that the quality of the object W can be correctly determined. In addition, the robot 100 according to this embodiment includes a load cell 12.
By correcting the couple load detected in 2 using the hand information, the couple load by the object W can be accurately obtained regardless of the attached hand unit 110. As a result, the quality of the object W can be determined not only by the weight of the object W but also by the couple load applied by the object W, so that the quality can be determined with high accuracy.

In the above description, for convenience of description, the hand unit 110 has been described as holding the object W from the side. However, the load cell 122 has three axial directions orthogonal to each other (X-axis direction, Y-axis direction).
(Axial direction, Z-axis direction) and couple loads around these three axes can be detected. Therefore, it is not always necessary to grip the object W from the side. Can be extended. Below, the case where the hand part 110 hold | grips the target object W from the diagonal direction is demonstrated as a modification.

C. Modified example:
FIG. 4 is an explanatory view showing a modified example in which the object W is extended so as to be gripped from an oblique direction. FIG. 4A shows the weight and centroid position of the object W and the weight and centroid position of the hand unit 110 when the object W is gripped from an oblique direction. That is, the weight of the object W is Gw, the center of gravity position of the object W is at a position Lw from the mounting surface of the hand unit 110 to the load cell 122, the weight of the hand unit 110 is Gt, and the center of gravity position is the load cell 122. It is assumed that the position is Lt from the mounting surface.

FIG. 4B shows the loads on the three axes (X axis, Y axis, and Z axis) detected by the load cell 122 and the couple loads around these three axes. In FIG. 4B, the direction along the central axis of the arm portion 120 is taken as the Z axis, the direction perpendicular to the Z axis toward the front side of the paper is taken as the X axis, and Z
A direction perpendicular to the axis and the X axis is taken as a Y axis. The magnitude of the load obtained by vector-composing the load Fz in the Z-axis direction detected by the load cell 122, the load Fy in the Y-axis direction, and the load Fx in the X-axis direction (not shown in FIG. 4B) is It should be the same as the sum of the weight Gw of the object W and the weight Gt of the hand unit 110. Therefore, if the weight Gt of the hand unit 110 read out as hand information is subtracted from the value obtained by vector-synthesizing the triaxial loads detected by the load cell 122, the object W can be obtained even when the object W is gripped from an oblique direction. The weight Gw of W can be obtained.

Further, the couple load Mx around the X axis detected by the load cell 122 should be a value obtained by adding the couple load by the object W and the couple load by the hand unit 110. Here, if the angle θ formed by the arm unit 120 with respect to the horizontal direction is known, the couple load applied by the hand unit 110 from the weight Gt of the hand unit 110 stored as hand information and the gravity center position Lt of the hand unit 110 is determined. Can be obtained as (Gt · Lt · cos θ). The arm part 120
The angle θ is not an angle formed with respect to the horizontal direction, but an angle formed with respect to the vertical direction (gravity direction) may be used. In this case, the couple load by the hand part 110 is (Gt · L
t · sin θ).

In the robot 100 according to the present embodiment, the movements of the plurality of joints provided in the arm unit 120 are controlled by the control unit 132, and when the angles of the respective joints are determined, the arm unit when gripping the object W is determined. An angle θ of 120 is determined. Therefore, the control unit 132 can obtain the angle θ of the arm unit 120 from the angle of each joint. Therefore, if the couple load (Gt · Lt · cos θ) by the hand unit 110 is calculated from these pieces of information and subtracted from the couple load Mx detected by the load cell 122, the couple load by the object W can be obtained. it can.

The angle θ of the arm unit 120 has been described as being calculated by the control unit 132, but the angle θ of the arm unit 120 may be directly detected by a sensor. When the angle at which the arm unit 120 grips the object W is determined, the angle θ of the arm unit 120 can be measured or calculated in advance. When the angle θ of the arm unit 120 is determined in advance, the hand unit 11 is used instead of the distance Lt indicating the center of gravity position of the hand unit 110.
The couple load (Gt · Lt · cos θ) due to 0 may be stored in the memory 112 as hand information. In the modified example, since the control unit 132 detects the angle of the arm unit 120, the control unit 132 corresponds to the “angle detection means” in the present invention.

As described above, even in the case of the modification example in which the object W is grasped from the oblique direction, the weight of the object W or the object W is corrected by correcting the load and the couple load detected by the load cell 122 based on the hand information. The couple load due to can be obtained. For this reason, even if the hand part 11
Even when 0 is replaced, it is possible to accurately determine the quality of the object W based on the weight of the object W and the couple load by the object W.

Although the robots of the present embodiment and the modified examples have been described above, the present invention is not limited to the above-described embodiments or modified examples, and can be implemented in various modes without departing from the gist thereof. .

For example, in the above-described modification example, the object W is grasped from the oblique direction. However, as illustrated in FIG. 5, the object W may be grasped from above. Also in this case, the load detected by the load cell 122 should be a sum of the weight Gw of the object W and the weight Gt of the hand unit 110. Therefore, the weight of the object W can be obtained by subtracting the weight of the hand unit 110 stored as hand information from the load detected by the load cell 122. In addition, the center of gravity of the object W and the center of gravity of the hand unit 110 are set to the Z of the load cell 122.
Except for the case of being on the axis, a couple load around the X axis or the Y axis appears in the load cell 122. Accordingly, the position of the center of gravity of the hand unit 110 is set to the distance from the Z axis to the X axis,
If described by the distance in the axial direction and stored as hand information, the couple load by the hand unit 110 can be calculated from the hand information, and the hand unit 110 can be calculated from the couple load detected by the load cell 122. By subtracting the couple load due to, the couple load due to the object W can be obtained. As a result, even when the hand unit 110 is replaced, it is possible to accurately determine the quality of the target object W based on the weight of the target object W or the couple load by the target object W.

100 ... Robot, 110 ... Hand part, 112 ... Memory,
120 ... arm part, 122 ... load cell, 130 ... main body part,
132: Control unit, W: Object

Claims (5)

A robot comprising: an arm unit; a hand unit that is detachably attached to a tip of the arm unit; and a control unit that controls an operation of the arm unit and the hand unit;
The hand part is provided with hand information storage means for storing hand information relating to the weight of the hand part,
The arm part is provided with a load detection means for detecting a load that the arm part receives from the hand part,
In the control unit,
Hand information reading means for reading the hand information from the hand information storage means;
Determining means for determining a component of a load by the object in the detected load based on the detected load and the read hand information;
A robot for determining whether or not the object is acceptable based on the determined load component of the object. The robot according to claim 1,
The hand information storage means is means for storing information on the center of gravity of the hand unit as the hand information,
The load detection means is means for detecting a couple load received from the hand portion in addition to the load,
The determining means includes a component of a couple load by the object in the detected couple load,
Means for determining based on the detected couple load and the hand information;
The robot is characterized in that the pass / fail judgment means is a means for judging pass / fail of the object based on a component of a load by the object and a component of a couple load by the object. The robot according to claim 2,
An angle detection means for detecting an angle formed by the arm portion holding the object with respect to a gravity direction or a horizontal direction;
The determination means is means for determining a component of a couple load due to the object based on the detected couple load, the hand information, and an angle of the arm unit. A robot control method comprising: an arm unit; and a hand unit that is detachably attached to a tip of the arm unit and grips an object,
A reading step of reading out hand information regarding the weight of the hand unit from the hand unit;
A detection step of detecting a load that the arm portion receives from the hand portion;
A determination step of determining a component of a load by the object in a load received by the arm unit based on a load received by the arm unit and the hand information;
And a determination step of determining pass / fail of the target object based on the determined load component of the target object. The control method according to claim 4, comprising:
The reading step is a step of reading information on the center of gravity of the hand part as the hand information,
The detection step is a step of detecting a couple load received by the arm unit from the hand unit in addition to the load,
The determining step is a step of determining a component of the couple load by the object in the couple load received by the arm unit based on the couple load received by the arm unit and the hand information.
The determination step is a step of determining pass / fail of the object based on a component of a load by the object and a component of a couple load by the object.

Images