JP2001113482A - Robot hand control method and controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot hand control method and a controller capable of gripping a gripped object in an almost constant operation time regardless of the size of the gripped object. SOLUTION: In this method for controlling actuation of a robot hand 34 having at least two gripping claws 39 for gripping a gripped object and a driving mechanism 36 for driving the gripping claws 39 so as to mutually approach/ separate, when gripping the gripped object W by the gripping claws 39 by mutually approaching the gripping claws 39, the gripping claws 39 are moved by a high speed feed up to this side approach position for contacting with the gripped object W, and afterwards, the gripping claws 39 are moved by a low speed feed up to gripping the gripped object W by contacting with the gripped object W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot hand used for automatically attaching and detaching an object such as a work to or from a main shaft of a machine tool, and more particularly, to controlling the operation of the robot hand. The present invention relates to a control method and a control device for performing the control.

[0002]

2. Description of the Related Art For example, in the field of machining using a machine tool, in order to improve the production efficiency by operating the machine tool day and night, it is necessary to automate the transfer, mounting, and removal of workpieces and jigs. In order to achieve such automation and unmanned operations, industrial robots (hereinafter referred to as
Robots) are often used.

Usually, the robot has a hand for gripping a workpiece or the like. The hand has at least two gripping claws for gripping an object to be gripped, such as a workpiece, and the gripping claws approach / separate from each other. And a driving mechanism for driving the motor. In addition, actuators such as air cylinders and hydraulic cylinders and electric motors such as stepping motors and servo motors are used as driving mechanisms for driving the gripping claws.

In recent years, small-lot production of many kinds has been advanced, and in extreme cases, different types of workpieces are supplied to a machine tool one by one and processed.
Therefore, the objects to be gripped such as workpieces and jigs and the like which are continuously supplied to the machine tool using the robot are also different for each piece. Are provided with a large operation stroke so that can be held by a common gripping claw.
That is, the operation stroke of the gripping claw is adjusted to the maximum dimension of the object to be gripped.

Conventionally, when an electric motor such as a stepping motor or a servo motor is used for the driving mechanism, the gripping operation of the gripping nail for gripping the object to be gripped is driven at a constant feed speed. Had become.

[0006]

However, when the gripping claw is operated at a constant feed speed as in the conventional hand described above, if the size of the object to be gripped is small, the gripping operation starts from the start of the gripping operation. There is a problem that the operation time until the gripping object is gripped, that is, the idle operation time becomes long, so that efficient processing cannot be performed. In particular, when the gripped portion includes a gripped object having a small thickness, it is necessary to set the feed speed of the gripping claw to an extremely low speed in order to prevent the occurrence of clamp distortion. The idle operation time became considerably long, and the machining efficiency was extremely reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a control method and control of a robot hand capable of gripping an object to be gripped in a substantially constant operation time regardless of the size of the object to be gripped. The purpose is to provide the device.

[0008]

Means for Solving the Problems and Their Effects According to the first aspect of the present invention for achieving the above object, at least two gripping claws for gripping an object to be gripped and the gripping claws are mutually connected. A method for controlling the operation of a robot hand having a drive mechanism for driving to approach / separate, wherein the gripping claws approach each other to cause the gripping claws to grip the object to be gripped. The gripping claws are moved at a high speed to an approaching position in front of contacting the gripped object,
Then, the gripping claw is moved at a low speed until the gripping claw contacts the gripped object and grips the gripped object.

According to the present invention, the gripping claw is moved at a high speed to the approach position before contacting the object to be gripped, and then is moved at a low speed until it contacts the object to be gripped and grips it. Therefore, even when the size of the object to be grasped is large or small and the object to be grasped is small, the operation time from the start of the grasping operation to the grasping of the object to be grasped, that is, the idle operation time, is minimized. Can be shortened,
Objects to be gripped having different dimensions can be gripped in substantially the same operation time. Therefore, even if the thickness of the gripped portion is thin,
In order to prevent clamping distortion, even if the object to be gripped needs to have the low-speed feed extremely low,
The gripping operation when gripping this can be performed in a very short time, and thus, efficient processing can be performed.

The above approach position differs depending on the external dimensions of the object to be grasped. Therefore, it is necessary to set an approach position for each object to be grasped. As one of the methods, an approach position is calculated in advance, and the approach position is commanded in an operation program or set as a parameter. However, it is preferable to calculate the approach position each time from the external dimensions of the object to be gripped, the position data and the external dimensions of the gripping claws, as in the invention according to claim 2 of the present invention. In the field of high-mix low-volume production, the external dimensions of the object to be gripped are various, and when the production quantity is extremely small, the task of calculating the approach position in advance becomes extremely complicated. is there.

The method can be suitably implemented by the apparatus according to the third aspect.
That is, an invention according to claim 3 of the present invention is directed to a robot hand including at least two gripping claws for gripping an object to be gripped, and a driving mechanism for driving the gripping claws to approach / separate from each other. An apparatus for controlling operation, comprising: a grasped object information storage unit that stores at least an outer dimension of a grasped object; a grasping claw information storage unit that stores at least position data and an outer dimension of a grasping claw; The grip claw contacts the gripped object based on the external dimensions of the gripped object stored in the object information storage unit, and the position data and external dimensions of the grip claw stored in the grip claw information storage unit. After calculating the approach position before performing, moving the gripping claw at a high speed to the approach position, and then moving the gripping claw at a low speed to a position where the gripper comes into contact with the gripped object and grips the gripped object. Previous Provided with gripping claw drive control unit for controlling the operation of the drive mechanism, characterized by being configured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view showing the entire machine tool according to the present embodiment provided with a robot.

As shown in FIG. 1, a machine tool 1 of the present embodiment
Supplies an NC lathe 10 that performs machining such as turning on a supplied workpiece, a stock device 20 that stores workpieces supplied to the NC lathe 10, and a workpiece stored in the stock device 20 to the NC lathe 10. It comprises a robot 30 as a loading device. The NC lathe 10 has a known configuration including a chuck 11, a front door 12, an operation panel 13, and the like, and a detailed description thereof will be omitted.

Although not shown in detail, the stock device 20 is a device for storing the work and the jaw plate supplied to the NC lathe 10, and for collecting and storing the processed work. For example, a structure in which a large number of mounting tables are connected endlessly by a chain or the like is provided so that a work, a jaw plate, and the like can be mounted on the mounting table. Then, the chain is driven by a drive motor or the like, and the above-mentioned placing table is turned, and an appropriately placed placing table such as a workpiece supplied to the NC lathe 10 is positioned at an unloading position, or a processed workpiece is taken out. The placement table is appropriately positioned at the collection position in order to collect the data. still,
The jaw plate as an object to be grasped is provided so as to be separable from the chuck body, and is provided with claws having a shape adapted to the shape of each work, and a plurality of jaws are provided according to the work to be processed by the NC lathe 10. Are prepared, and the jaw plate mounted on the chuck body is exchanged according to the work to be machined.

The robot 30 has a robot body 31
4 and a control device 45 shown in FIG. 4. The transfer guide portion 41 is disposed above the NC lathe 10 along the longitudinal direction thereof, and is engaged with the robot main body 31. A guide rail 42 that guides the movement together;
It comprises three pillars 43 for supporting the guide rail 42.

The robot body 31 includes hands 34, 3 for gripping an object to be gripped, such as the work or the jaw plate.
4 and a slide arm 32 which is provided movably in the up and down direction (directions indicated by arrows CD) and supports the hands 34 and 34 at the lower end, and the robot body 31 is indicated by arrows along the guide rails 42. A main body drive mechanism 33 for moving the slide arm 32 in the direction of arrow CD, and rotating the hands 34, 34 in the direction of arrow IJ shown in FIG. Become. The main body driving mechanism 33 is shown in FIG. 4, and is not shown in FIG. The hands 34, 34 are provided back to back with each other, and are rotated by 180 ° in the directions indicated by the arrows IJ so that they are inverted.

As shown in FIGS. 2 and 3, the hand 3
Reference numeral 4 denotes a hand body 35 having a built-in speed reduction mechanism, three drive shafts 37 rotatably disposed on the mounting surface 35a of the hand body 35, and driven to rotate around the axis by the speed reduction mechanism, and one end. Are respectively fixed to the drive shafts 37, gripping claws 39 connected to the other ends of the arm members 38 so as to protrude from the arm members 38, respectively, and the three It comprises a Y-shaped pushing plate 40 provided between the drive shafts 37 and at the center of the mounting surface 35a, and a servomotor 36 for inputting power to the speed reduction mechanism. The hand drive mechanism 36 shown in FIG. 4 is constituted by the speed reduction mechanism and the servo motor 36a. Further, the drive shafts 37 are evenly arranged with reference to the center position of the mounting surface 35a.

Power is transmitted from the servomotor 36 to the drive shafts 37 via the speed reducers, and the drive shafts 37 rotate in synchronization with the directions indicated by arrows EF, respectively. The gripping claw 39 turns around the axis of the drive shaft 37 in the same direction. Thus, when the gripping claws 39 pivotally move in the direction indicated by the arrow F, the gripping claws 39 approach each other to reduce the distance therebetween, and a gripped object such as a work W is held between the gripping claws 39. (Clamping), and conversely, when the gripping claws 39 pivotally move in the direction of the arrow E, the gripping claws 39 are separated from each other and the interval therebetween is widened, and the object to be gripped is released (unclamped). You.

The pushing plate 40 is provided so as to be movable in a direction away from and attached to the mounting surface 35a of the hand main body 35, that is, in the direction indicated by the arrow GH, and by a biasing means (not shown) in the direction indicated by the arrow H. Has been energized.

As shown in FIG. 4, the control device 45 comprises:
Main control unit 46, main body drive control unit 47, grip claw drive control unit 48, gripped object information storage unit 49, and grip claw information storage unit 5
0. The main control unit 46 is a processing unit that executes a part corresponding to a main routine of the operation program,
The main body drive control unit 47 is a processing unit that executes an operation program part related to the operation of the robot main body 31, and the gripping claw drive control unit 48 is a processing unit that executes an operation program part related to the operation of the hand 34.

The grasped object information storage section 49 is a function section for storing data relating to the outer diameter of the grasped object such as the work W. The grasped claw information storage section 50 stores the position of the grasped claw 39 of the hand 34 and This is a functional unit that stores data relating to dimensions. Specifically, for example, the work W
When the workpiece W is gripped, as shown in FIG.
₁ is appropriately stored in the object information storage unit 49 via input means, while the outer diameter d _{2 of} the gripper 39 and the gripper 39 are
Is the angle data α,
When the gripping claw 39 is at a position (approach position) just before contact with the workpiece W, the gap between the gripping claw 39 and the workpiece W is converted into a diameter value d ₃ . The center distance a of the hand 35 and the center distance b of the hand body 35 and the drive shaft 37 are appropriately determined via input means.
0 is stored. In the figure, _{L 1} and _{L 2} is the center line of the hand body 35. Also, the angle data α, the center distance a
And the center distance b are fixed values, which are obtained in advance by measurement or the like. On the other hand, the diameter converted value d ₃ of the gap is a value arbitrarily set.

As described above, the main body drive control unit 47
Is a processing unit that executes an operation program portion related to the operation of the robot main body 31. The operation program is executed to move the robot main body 31 in the direction of arrow AB or to move the slide arm 32 in the direction of arrow CD. The operation of the main body drive mechanism 33 is controlled so as to move the slide arm 32 about the axis of the main body, or to rotate the slide arm 32 about its axis.

As described above, the grip claw drive control section 48 is a processing section for executing an operation program portion relating to the operation of the hand 34, and specifically, FIGS.
Are sequentially executed. The processing shown in FIG. 6 relates to the operation of turning the arm member 38 and the gripping claw 39 in the direction of arrow F to clamp the gripped object. When the execution command of the clamping operation is input from the main control unit 46, Then, the grip claw drive control unit 48 firstly determines the outer diameter dimension d _{1 of the} gripped object stored in the gripped object information storage unit 49.
Is read (step S1), and the servo motor 36
Is turned off (step S2).

Next, the grip claw drive control section 48 stores the outer diameter dimension d ₂ , the angle data α, the gap diameter conversion value d ₃ , the center distance a and the center distance b stored in the grip claw information storage section 50. Is read (step S3), and the gripper 39
Then, the angle data β at the position just before contact with, that is, the approach position is calculated (step S4). The state when the gripping claw 39 is at the approach position is shown in FIG. 5, and when α−β = γ, the following Equation 1 is derived from the cosine theorem.

[0025]

(Equation 1)

Therefore, the angle γ can be expressed by the following equation (2).

[0027]

(Equation 2)

Since β = α−γ, the angle β to be obtained can be expressed by the following equation (3).

[0029]

(Equation 3)

In step S4, the angle β of the approach position is calculated by the above equation (3). Next, the gripping claw drive control unit 48 drives the servomotor 36 to turn the gripping claw 39 at high speed feed to the approach position calculated in step S4, that is, the angle β (step S5), and the gripping claw 39 After reaching the approach position (step S6), the servo motor 36 is driven to turn the gripping claw 39 at a clamp feed speed lower than the high feed speed (step S7). Thereafter, the gripping claw drive control unit 48 monitors the servo delay amount of the servo motor 36, and when the gripping claw 39 comes into contact with the work W and the servo delay amount exceeds the reference value, the gripping claw 39 Is detected (step S8), the drive of the servomotor 36 is stopped, and a brake is applied to the servomotor 36 (step S9), thereby terminating the clamp operation processing.

On the other hand, the processing shown in FIG. 7 relates to the operation of unclamping the object to be gripped by turning the arm member 38 and the gripping claw 39 in the direction of arrow E. When the operation execution command is input, the grip claw drive control unit 48 first
Is turned off (step S11), and the servo motor 36 is driven to turn the gripper 39 at the high-speed feed speed to the origin position (the position shown by the one-dot chain line in FIG. 5) (step S12). Next, after confirming that the gripping claw 39 has returned to the origin position (step S13), the gripping claw drive control unit 48 checks the servo motor 36
Is stopped and the brake is applied to the servo motor 36 (step S14), and the processing of the unclamping operation is completed.

According to the machine tool 1 of the present embodiment having the above-described configuration, for example, when the workpiece W is supplied from the stock apparatus 20 to the NC lathe 10, the supply operation is performed according to the following procedure. Incidentally, the gripping claws 39 of the hands 34, 34 are at the origin position, the slide arm 32 is at the rising end position in the direction of arrow D, and the robot body 31 is located at an appropriate take-out position above the stock device 20. Shall be. Further, the gripping claws of the chuck 11 are in an open state and the work W is not gripped, and the data on the outer diameter of the work W is stored in the gripped object information storage unit 49 in the gripping claw information storage unit 50. It is assumed that data relating to the position and dimensions of the gripping claws 39 are stored in advance.

First, the main body drive control section 47 drives the main body drive mechanism section 33 to move the hands 34, 34 in the direction of arrow I or J.
1 and the slide arm 32 is moved in the direction of arrow C, and the hand 34 is positioned at the unloading position in the stock apparatus 20. After that, the slide arm 32 is further moved in the direction of arrow C by a predetermined amount.
As a result, the pushing plate 40 is pressed against the work W.

Next, the gripping claw drive control section 48 sequentially executes the processing procedure shown in FIG. 6 to move the gripping claw 39 in the direction of arrow F. At this time, the gripping claw 39 is driven at a high speed to the calculated approach position and then driven at a lower clamp feeding speed to grip the outer peripheral portion of the work W.

Next, the main body drive control section 47 drives the main body drive mechanism section 33 to move the slide arm 32 to the rising end position in the direction of arrow D, and the hands 34, 34 are withdrawn from the inside of the stock apparatus 20. Then, the hands 34, 34 are rotated 90 ° in the direction of arrow I. Then, the robot body 31
Is driven in the direction of arrow B to move it to a position where it can enter the NC lathe 10, and then the slide arm 32 is lowered in the direction of arrow C so that the workpiece W held by the hand 34 faces the chuck 11. After that, the robot body 31 is moved in the direction of the arrow A by an appropriate distance. Thereby, the work W gripped by the hand 34 is located between the gripping claws of the chuck 11.

Next, the gripping claw drive control section 48 sequentially executes the processing procedure shown in FIG. 7 to move the gripping claw 39 in the direction of arrow E. As a result, the gripping of the workpiece W by the gripping claws 39 is released, and the workpiece W is
Is pressed against the reference surface set on the chuck 11. Then, the gripping claws of the chuck 11 are closed, and the work W is gripped by the chuck 11.

In this way, the work W is held by the chuck 11
After being gripped by the main body, the main body drive control unit 47 moves the robot main body 31 by an appropriate amount in the direction of arrow B, and then moves the slide arm 32 to the rising end position in the direction of arrow D. It is moved in the direction A to return to the initial position.

As described above, the workpiece W is supplied from the stock apparatus 20 to the NC lathe 10. Thereafter, when processing the same kind of work, one hand 3
4, the work W in the stock apparatus 20 is gripped and the work W is taken out of the stock apparatus 20.
4 and 34 are reversed, the processed work W gripped by the chuck 11 is gripped by the other hand 34 and removed from the chuck 11, and then the hands 34 and 34 are again rotated and the one hand The workpiece W gripped by the chuck 34 is gripped by the chuck 11, and thereafter, the processed workpiece W gripped by the other hand 34 is collected in the stock apparatus 20.

As described in detail above, according to the machine tool 1 of the present embodiment, when the hand 34 grips the workpiece W as an object to be gripped, the gripping claw 39 is moved up to the approach position before contact with the workpiece W. Is moved at high speed, so that even when gripping a workpiece W having a small outer diameter, the operation time from the start of the gripping operation to gripping the workpiece W, that is, the idle operation time, is as short as possible. The workpieces W having different outer diameters can be gripped in substantially the same operation time. Therefore, even if the workpiece W requires the low-speed feed to be extremely slow in order to prevent clamping distortion due to the small thickness of the gripped portion, the gripping operation when gripping the workpiece is extremely small. The processing can be performed in a short time, and thus, efficient processing can be performed.

In this embodiment, the gripper claw drive controller 48 calculates the approach position from the outer diameter of the work W, the position data of the gripper 39 and the outer diameter each time, and returns to the calculated approach position. Since the gripping claw 39 is moved at a high speed, complicated work is required even when the outer diameter of the workpiece W to be machined is varied and the production quantity is extremely small. And efficient processing can be realized.

Although a specific embodiment of the present invention has been described above, it is needless to say that a specific embodiment of the present invention is not limited to this. For example, the hand 3
The configuration of 4 is not limited to that of the present example, and the gripping claws 39 may be provided so as to move directly. In this case, the formula for calculating the approach position is naturally different from the above formula. In addition, the procedure from step S1 to step S3 shown in FIG. 6 may be slightly changed before or after the allowable range.

In the above description, after the movement of the slide arm 32 and the robot body 31 is completed,
Although the high-speed movement to the approach position 9 is started, it may be executed simultaneously with the movement of the slide arm 32 and the robot main body 31 and the high-speed movement of the gripper 39 to the approach position. This makes it possible to further reduce the gripping operation time.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire machine tool according to an embodiment of the present invention.

FIG. 2 is a front view showing a hand according to the embodiment.

FIG. 3 is a left side view of the hand shown in FIG. 2;

FIG. 4 is a block diagram illustrating a schematic configuration of a control device according to the present embodiment.

FIG. 5 is an explanatory diagram for explaining an operation of the grip claw drive control unit according to the embodiment.

FIG. 6 is a flowchart illustrating a processing procedure of a clamp operation in a gripping claw drive control unit according to the present embodiment.

FIG. 7 is a flowchart illustrating a processing procedure of an unclamping operation in the gripping claw drive control unit according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Machine tool 10 NC lathe 20 Stock apparatus 30 Robot 31 Robot main body 32 Slide arm 34 Hand 36 Servo motor 37 Drive shaft 38 Arm member 39 Gripping claw 45 Control device 46 Main control unit 47 Main unit driving control unit 48 Gripping claw driving control unit 49 Grasped object information storage unit 50 Gripped claw information storage unit

Claims (3)

[Claims] 1. A method for controlling the operation of a robot hand comprising at least two gripping claws for gripping an object to be gripped and a drive mechanism for driving the gripping claws to approach / separate from each other. The gripping claws are moved closer to each other, and when the gripping claws grip the object to be gripped, the gripping claws are moved at a high-speed feed to an approach position before contacting the gripped object, and thereafter, A method of controlling a robot hand, comprising: moving the gripping claws at a low speed until the gripping claws come into contact with the gripped object and grip the gripped object. 2. The method according to claim 1, wherein the approach position is calculated based on at least an outer dimension of the object to be gripped, position data and an outer dimension of the grip nail, and the grip nail is fed at high speed to the calculated approach position. Claim 1
The control method of the described robot hand. 3. An apparatus for controlling the operation of a robot hand comprising at least two gripping claws for gripping an object to be gripped, and a drive mechanism for driving the gripping claws to approach / separate from each other. A gripped object information storage unit that stores at least the external dimensions of the gripped object; a gripping claw information storage unit that stores at least the position data and the external dimensions of the gripping claws; and at least the gripped object information storage unit. Based on the external dimensions of the object to be gripped, and the position data and external dimensions of the gripping claws stored in the gripping nail information storage unit, calculate an approach position before the gripping claws come into contact with the object to be gripped. Controlling the operation of the drive mechanism so that the gripping claw is moved at a high speed to the approach position and then moved at a low speed to a position where the gripping claw contacts the object to be gripped and grips the object to be gripped. A control device for a robot hand, comprising: a gripping claw drive control unit that performs the control.