JPH09155547A - Device for detecting working line of robot and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unnecessitate the protective mechanism of a sensor unit and to make the sensor unit small in size and light in weight by enabling the sensor unit to be rotated around the tool shaft through the rotation of a hollow shaft when the sensor unit is held by a robot. SOLUTION: A sensor unit 30 for detecting the position of a welding line and the shape of a work 20 is equipped rotatably around the shaft of a welding torch 10 attached to the top end of a welding robot 1. The sensor unit 30 is freely attachable to and detachable from the welding torch 10, in the moving area where a sensor base 40 is provided for restraining the sensor unit 30. The sensor unit 30 is engaged with the sensor base 40 during welding or idling of the robot 1. Thus, the sensor unit 30 is clamped by the robot 1 only at the time of sensing, thereby dispensing with the protective mechanism of the sensor unit 30 at the time of welding and enabling the unit to be made small in size and light in weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mounts a sensor unit for measuring the position of a machining work line near a machining tool of a robot, and drives the robot before the actual machining work to sense the machining work line by the sensor unit. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining work line detection device for a robot that executes an operation and a control method thereof.

[0002]

2. Description of the Related Art In a welding robot, welding work is performed by moving a welding torch attached to the arm tip of the robot along a welding line.

In order to cope with the installation error of the work during this welding work and the dimensional variation of the work itself, the position of the welding line and the groove shape are sensed prior to actual welding, and based on this sensing data. A method of correcting the position and locus data of the welding torch obtained by teaching and performing actual welding is used.

In order to perform the above sensing work, a non-contact type sensor unit such as an optical distance sensor is attached to the robot, and each axis of the robot is driven to scan the sensor unit near the welding line. It was

When the sensor unit as described above is mounted on the robot, it is desirable that the mounting position of the sensor is near the welding torch at the tip of the arm of the robot in consideration of the detection range of the sensor and the operation range of the robot. . However, at the time of welding, the sensor may be damaged by heat, spatter, fume, or the like, and in order to protect the sensor, it is necessary to isolate the sensor from the heat of the welded portion at the time of welding.

Therefore, in Japanese Patent Laid-Open No. 154658/1993, a laser slit optical sensor mounted on a robot detects a welding line, and the robot is operated in accordance with the detected welding line to perform automatic welding work. In a welding robot of the type, a sensor box including a laser diode for projecting a laser beam, an optical system, and a CCD camera for monitoring a groove portion of a welding member irradiated with the laser beam is arranged around the welding torch. The sensor box is cooled by cold air with a low-temperature air generator and is cooled by circulating cooling water.The tip of the welding torch is covered with a tube having a tapered surface, and compressed air is used to generate a negative pressure flow in the tapered opening. I try to suck in the fume.

Further, in this prior art, the sensor box is constructed so as to be rotatable around the welding torch by a hollow electric motor arranged around the welding torch, and the sensor box is rotated in the forward traveling direction of the welding torch by the rotation of the motor. Positioning is always performed at the position to enable tracking control for a bent welding line.

As described above, in this conventional technique, the sensor provided around the welding torch of the welding robot is provided with a protection mechanism for directly protecting heat, fume, spatter, etc. at the time of welding.

Therefore, according to this conventional technique, the structure of the sensor portion becomes large and heavy due to the addition of the protection mechanism, and the occurrence rate of interference between the sensor box and the work during search or welding increases. is there. Moreover, the cost increase due to the addition of the protection mechanism is inevitable.

Further, according to the method of performing sensing before actual welding, instead of the copying control as in the above-mentioned prior art,
Since the workpiece is closer to the workpiece during welding than during sensing, the existence of the sensor itself becomes an obstacle regardless of the size, and many places where welding is impossible occur.

Further, according to this prior art, since the hollow electric motor is arranged around the welding torch and the hollow electric motor is used to rotate the sensor box,
The diameter around the welding torch becomes thicker, the part becomes larger and heavier, and the possibility of interference with the work increases.

By the way, as a non-contact type sensor for detecting the position and shape of a welding line, there is a laser distance sensor using a laser and a PSD (optical position detecting device).

This laser distance sensor projects a laser spot light, receives the light diffusely reflected by a work through a lens and receives the light with a PSD, and based on the displacement output of the PSD, the distance from the sensor to the work is determined by triangulation. It is something to measure.

When the surface shape of a workpiece is detected by using this laser distance sensor, the laser distance sensor has an optical axis plane composed of a light emitting axis and a light receiving axis in the scanning direction as shown in FIG. 11 (a). You must take a posture that is perpendicular to it.

This is because, as shown in FIG. 11B, when scanning is performed with the optical axis plane parallel to the scanning direction, as shown in FIG. It may be blocked by.

Further, in this type of laser distance sensor, the PSD is arranged so that proper detection is performed when the optical axis plane is perpendicular to the scanning direction. In principle, the measured value is disturbed by the influence of the contrast of the arc surface. For example, FIG.
As shown in FIG. 3, when the laser distance sensor takes two postures A and B with respect to the moving direction of the object to be measured, the output data of the sensors in the respective postures A and B are shown in FIGS. 14 (a) (b). As shown in. That is, when the posture B is taken,
As shown in (b), there is a clear disturbance in the measurement data due to the influence of the surface contrast.

As described above, the laser distance sensor has an appropriate attitude in the scanning direction, but the attitude of the sensor unit has not been determined in consideration of this in the related art. Was occurring.

Further, when the sensor unit is fixedly attached to the tip of the welding torch and the posture of the laser distance sensor in the scanning direction is prioritized to determine the posture of the robot around the torch axis at the time of sensing, sensing is performed. Depending on the location, there is a location where sensing is impossible because the robot or tool interferes with the work.

Further, since the laser distance sensor is a non-contact type, the sensing operation is performed at a certain distance from the welding line. Therefore, even if interference does not occur during sensing, the welding torch approaches the welding line. In the above, the above interference may occur.

Here, a method of avoiding interference with the work by changing the posture of the torch or the robot around the torch axis during welding is different from that during sensing. However, if the torch axis or the robot's posture around the torch axis changes between sensing and welding, the tip stop error (the tip position due to changing only the robot's posture) due to the NC error (error in the coordinate system) of the robot Variation) has a great adverse effect on the sensing accuracy. When the welding torch and the robot have the same posture and only the torch position is separated during sensing and welding, the span error (error caused by the length) caused by the NC error of the robot is small, and The accuracy is not so affected.

As described above, if the welding torch and the robot have different postures during welding and during sensing, the sensing accuracy itself is extremely reduced.

The present invention has been made in view of the above circumstances, and the sensor unit is reduced in size and weight to reduce the possibility of interference with a work, thereby expanding the types of work that can be sensed and reducing the apparatus cost. It is an object of the present invention to provide a processing work line detection device for a robot that is lowered.

Further, according to the present invention, the detection of the working line of the robot capable of performing the sensing operation of the working line with high accuracy without the influence of the tip stop error due to the NC error of the robot, in which the interference with the work is reduced. An object is to provide a method of controlling a device.

[0024]

According to the present invention, a sensor unit having a sensor for measuring the position and shape of a machining work line in a non-contact manner is mounted in the vicinity of a machining tool of a robot, and the robot is mounted before the actual machining work. In a machining work line detection device of a robot that is driven to perform a sensing operation of a machining work line by the sensor unit, a hollow shaft that surrounds the machining tool of the robot and rotates around the machining tool,
The robot is provided with a rotation mechanism which is arranged on a tool bracket to which the processing tool is attached and rotationally drives the hollow shaft, and the sensor unit is separated from the robot, and the hollow shaft of the robot is attached to the sensor unit. A clamp mechanism for holding the clamp unit is provided so that the hollow shaft of the robot is clamped by the clamp mechanism of the sensor unit when a sensing operation is performed, and the sensor unit is detached from the robot during an actual machining operation. And a control means for controlling the robot, wherein the sensor unit can be attached to and detached from the robot and the sensor unit can be rotated around the tool axis by rotation of the hollow shaft when the sensor unit is gripped by the robot. It is characterized by doing I do.

That is, according to the present invention, the sensor unit is detachable, and the sensor unit is clamped to the robot only at the time of sensing, thereby eliminating the need for a sensor unit protection mechanism at the time of welding, thereby reducing the size and weight of the apparatus. ing. Further, on the robot side, a hollow shaft that surrounds the machining tool of the robot and rotates around the machining tool, and a rotation mechanism that is disposed in a tool bracket to which the machining tool is attached and that rotationally drives the hollow shaft are provided. Place the minimum configuration consisting of
By adding only a clamping mechanism for clamping the hollow shaft to the sensor unit side, a mechanism for rotating the sensor unit around the torch axis is configured.

Further, according to the present invention, a sensor unit including a distance sensor for measuring the distance to the work by triangulation using light is mounted near the machining tool so as to be rotatable around the machining tool of the robot, and the actual machining is performed. In a machining work line detection device of a robot that measures the position and shape of the machining work line by sensing and scanning the machining work line with the distance sensor according to the movement of the robot before work, in the sensing, the robot and It is characterized by controlling the sensor unit.

(A) The postures of the robot and the machining tool are the same as the postures of the robot and the machining tool at the time of actual machining, which are preset with respect to the machining work line.

(B) The sensor unit is placed around the machining tool so that the optical axis plane of the distance sensor is substantially perpendicular to the light cutting plane determined by the distance detection direction of the distance sensor and the scanning direction of the distance sensor. Rotate.

(C) After the rotation of the sensor unit is completed, the robot is driven to scan the sensor unit in the predetermined scanning direction.

According to the invention, during the sensing work,
The postures of the robot and the machining tool are the same as the preset postures of the robot and the machining tool during actual machining. Then, while maintaining this posture, the sensor unit is rotated around the processing tool so that the optical axis surface of the distance sensor is substantially perpendicular to the predetermined scanning direction. When this rotation is completed, the robot is driven to scan the sensor unit in the predetermined scanning direction.

That is, according to the present invention, the posture of the robot during the sensing work is the same as that during the machining work, and the optical axis surface of the distance sensor is always substantially perpendicular to the predetermined scanning direction during the sensing. The azimuth angle of the sensor unit around the torch axis is controlled so that high-precision sensing work can be performed without being affected by the tip stop error.

[0032]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

The following embodiment is an application of the present invention to a welding robot for performing arc welding work.

FIG. 2 shows a schematic configuration example of a welding robot system. A welding torch 10 is attached to the tip of a welding robot 1 (in this case, a 6-axis articulated robot),
Further, a sensor unit 30 for detecting the position and shape of the welding line of the work 20 is attached to the welding torch 10 so as to be rotatable around the axis of the welding torch. The sensor unit 30 is detachable from the welding torch 10.

Further, within the moving range of the welding torch 10 of the welding robot 1 (in this case, the loading platform 2 of the welding robot 1 is used).
And a sensor base 40 for locking the sensor unit 30.
Is provided. The sensor unit 30 is locked to the sensor base 40 when the robot 1 is performing a welding operation or when the robot is at rest, and is attached to the robot 1 when the welding line is sensed. It

The sensor controller 50 processes the sensor data sensed by the sensor unit 30, and based on the processing result, the robot controller 60.
The robot controller 60 drives and controls the robot 1 based on a command from the sensor controller 50, teaching data, or the like.

FIGS. 3 (a) and 3 (b) show the detailed structure in the vicinity of the welding torch of the welding robot 1. Differences between FIGS. 3 (a) and 3 (b) are as follows.
The angle around the welding torch axis of the sensor unit 30 is different by 90 degrees.

In FIG. 3, the tip arm 3 of the welding robot 1 is provided with a wrist 4 which is rotatable in the vertical direction (arrow a) with respect to the tip arm 3, and the wrist 4 has a torch. The welding torch 10 is attached via the bracket 5. The torch bracket 5 and the welding torch 10 are integrally rotated by the rotation of the wrist 4 (in the direction of the arrow b) around the wrist shaft 4. A welding nozzle 6 is provided at the tip of the welding torch 10, and a welding wire 7 is projected from the welding nozzle 6.

The sensor unit 30 which is detachably attached to the welding torch 10 is a distance sensor (displacement sensor).
31 and the welding torch 1 connected to the distance sensor 31.
It is composed of a clamp mechanism 32 for clamping 0.

The distance sensor 31 is composed of a projector for projecting a laser spot light, a PSD (optical position detector) for receiving the light diffused and reflected by the work through a lens, and the like.
The distance to the work is calculated by the triangulation method based on the displacement output of PSD, and this is output to the sensor controller 50.

Details of the clamp mechanism 32 will be described later. In FIG. 3, 8 is a torch cable,
Reference numeral 9 is a sensor cable for electrically connecting the sensor unit 30 and the sensor controller 50, and 11 is a motor.

FIG. 1 shows an example of a sectional structure in the vicinity of the welding torch 10 and the torch bracket 5.

In FIG. 1, a cylindrical shaft (hollow shaft) 12 that surrounds the welding torch 10 and rotates around the welding torch 10 is provided around the welding torch 10. Cylindrical shaft 1 by transmitting rotation
2 is rotatable. The rotation of the motor 11 is controlled by the sensor controller 50.

That is, the pulley 14 is connected to the output shaft 13 of the motor 11, and the rotation of the pulley 14 is such that the welding torch 10 is inserted through the timing belt 15 into the pulley 1.
6. The cylindrical shaft 12 is connected to the pulley 16 by a bolt 17, and therefore the rotation of the pulley 16 causes the cylindrical shaft 12 to rotate around the welding torch 10. In FIG. 1, 17 is a bearing.

As described above, since the cylindrical shaft 12 can be rotated around the welding torch by the motor 11, the cylindrical shaft 12 is gripped by the clamping mechanism 32 of the sensor unit 30 shown in FIG. Then, the rotation of the cylindrical shaft 12 causes the sensor unit 30 to rotate around the welding torch 10.

Next, with reference to FIGS. 4 to 6, details of the clamp mechanism 32 of the sensor unit 30 and the sensor base 4 will be described.
0 will be described in detail.

In FIG. 4, the sensor unit 30 is the robot 1
The welding torch 10 is attached to the welding torch 10, and the clamping mechanism 32 clamps the welding torch 10. ,
In the clamp mechanism 32, the first plate 33 and the first holding block 34 are connected by a connecting body (not shown), and the second plate 36 and the second holding block 37 are connected by a connecting body (not shown). That is, the first plate 33 and the first grip block 34 are integrated into the pin 4
1, the second plate 36 and the second grip block 37 also move integrally along the pin 41.
The clamping surfaces of the first and second grip blocks 34, 37 are arcuate so that the welding torch 10 can be gripped.

Further, the first plate 33 and the second plate 3
A compression spring 42 guided by a guide pin 41 is provided between the first plate 33 and the second plate 36 in a direction in which the both plates 33, 36 expand. Being energized.

The distance sensor 31 is the second plate 36.
It is located on the lower side of and is fixed to the first block 34.

According to the structure of the clamp mechanism 32,
If the first plate 33 and the second plate 36 move away from each other, the first and second holding blocks 34, 37
Moves toward and clamps the welding torch 10.

Further, the first plate 33 and the second plate 3
When 6 and 6 move closer to each other, the first and second grip blocks 34 and 37 move away and release the welding torch 10.

On the other hand, the sensor base 40 is the welding robot 1.
Attached to the cargo bed 2 of the two grip plates 4
5, 46 and an air cylinder 47.

Next, referring to FIGS. 4 to 6 and FIGS. 7A to 7D, the sensor unit 3 loaded in the welding robot 1 is described.
The movement of each part until 0 is locked to the sensor base 40 will be described.

First, in the state shown in FIGS. 4 and 7 (a), the sensor unit 30 is in a state of being clamped to the welding torch 10 of the welding robot 1 by the clamp mechanism 32, and the sensor is detected by the movement of the robot 1. Approaching base 40.

Next, as shown in FIGS. 5 and 7 (b),
When the positioning of the sensor unit 30 with respect to the sensor base 40 is completed by the movement of the robot 1, the piston rod 52 of the air cylinder 47 of the sensor base 40 extends and presses the first plate 33 of the clamp mechanism 32. As a result, the distance between the first and second plates 33 and 36 is reduced, the distance between the first and second grip blocks 34 and 37 is correspondingly increased, and the welding torch 10 is released from the clamp mechanism 32.

Next, as shown in FIG. 7C, the robot 1 is driven so that the welding torch 10 is moved upward, so that the sensor unit 30 is inserted into and removed from the robot 1.

When the sensor unit 30 is detached from the robot 1 in this way, the piston rod 52 of the air cylinder 47 of the sensor base 40 is retracted, as shown in FIGS. 6 and 7D. As a result, the clamp mechanism 3
The distance between the two first and second plates 33 and 36 gradually increases, and then the first and second plates 33 and 36 come into contact with the grip plates 45 and 46 of the sensor base 30, respectively. Then, finally, the sensor unit 30 is locked and fixed to the sensor base by the urging force of the compression spring 42 of the clamp mechanism 32.

The operation when the sensor unit 30 locked to the sensor base 30 is loaded on the robot 1 side is the reverse of the above. First, the piston rod 52 of the air cylinder 47 is extended from the state shown in FIG. By doing so, as shown in FIG. 5, the gap between the first and second gripping blocks 34, 37 of the clamp mechanism 32 is widened so that the welding torch 10 can be inserted into these blocks 34, 37.

In this state, the robot 1 is driven to insert the welding torch 10 between the first and second gripping blocks 34 and 37 of the clamp mechanism 32, and then stopped.

Next, the air cylinder 4 of the sensor base 40
By retracting the piston rod 52 of No. 7, the gap between the first and second grip blocks 34, 37 is shortened, and as a result, the grip force of the first and second grip blocks 34, 37 by the urging force of the compression spring 42. The welding torch 10 is clamped by. The first and second grip blocks 34, 3
A clearance is provided between the first plate 33 of the clamp mechanism 32 and the gripping plate 45 of the sensor base 40 so that the sensor unit 30 is free from the sensor base 40 when the welding torch is clamped by the sensor unit 30. Therefore, by driving the robot 1 thereafter to move the sensor unit 30 upward or downward, the sensor base 40 moves from the sensor base 40 to the sensor unit 3.
0 can be removed.

In this way, the sensor unit 30 is loaded on the robot 1.

Next, the operation of sensing the position and shape of the welding line of the work 20 by the sensor unit 30 will be described.

At the time of this sensing, for example, as shown in FIG.
A sensing scan as shown in (b) is executed.

FIG. 8 (a) shows an example of scanning of the welding pattern of the lead-type welding line, in which the sensor unit 30 is first scanned in parallel with the welding line to detect the leading end of sensing (scanning line (a)). Next, the sensor unit 30 is scanned in the negative direction perpendicular to the welding line (scanning line (a)). Next, the sensor unit 30 is scanned in the opposite direction (scanning line (c)). Thereafter, similarly, scanning in the reciprocating direction is repeated at right angles to the welding line.

FIG. 8B shows an example of scanning of fillet welding line. First, the sensor unit 30 is scanned in parallel to the welding line to detect the leading edge of sensing (scanning line (a)). Next, the sensor unit 30 is scanned in the negative direction perpendicular to the welding line (scanning line (b)). Thereafter, in the same manner, scanning in only one direction is repeated at right angles to the welding line.

Next, a series of operations during sensing will be described with reference to the flowchart of FIG.

First, as shown in FIGS. 7D to 7A, the sensor unit 30 locked to the sensor base 40 is mounted on the robot 1 as described above (step 10).
0). At the time of this mounting, regarding the rotation angle of the sensor unit 30 around the welding torch shaft 10, the sensor base 4
When the sensor controller 50 recognizes the angular position when the sensor unit is mounted at 0 as the origin of the motor 11, the sensor unit 30 can be rotationally controlled to an arbitrary angular position around the torch axis, and the motor can be rotated. 1
The sensors for detecting the origin 1 can be omitted.

Next, with the sensor unit 30 loaded, the welding robot 1 moves the sensor unit 30 to a predetermined search position on the welding line to be sensed (step 110).

However, the robot 1 is drive-controlled so that the postures of the welding torch 10 and the welding robot 1 at the time when the movement to the search position is completed are the same postures as during actual welding (step 120). ). That is, the attitudes of the welding torch 10 and the welding robot 1 at the time of sensing (particularly the attitude around the torch axis = the attitude of the torch bracket 5 with respect to the welding torch 10) are made to be the same as those at the time of actual welding.

That is, the welding torch 10 at the time of sensing
And, if the posture of the welding robot 1 is made different from that at the time of actual welding, a tip stop error occurs due to the NC error of the robot, so these are made the same.

The welding torch 10 and the posture around the torch axis during welding are determined in advance for each welding line so that welding work can be performed without the tip of the robot or the welding torch interfering with the work 20. Has been done.

For example, in FIG. 10 (a), the attitude of the torch bracket 5 during welding is set to be perpendicular to the welding line, but in this case, the attitude of the torch bracket 5 is also during sensing. Make a right angle to the weld line. Further, in FIG. 10 (b), the attitude of the torch bracket 5 during welding is set to be parallel to the welding line, but in this case, the attitude of the torch bracket 5 is aligned with the welding line during sensing. Make them parallel to each other.

Next, the sensor controller 50 drives the motor 11 so that the optical axis surface of the sensor unit 30 mounted on the welding robot 1 is perpendicular to the scanning direction of the sensor unit 30 and welds the sensor unit 30. Torch 1
Rotate around 0 (step 130).

For example, in FIG. 10A, since the scanning direction of the sensor unit 30 is a direction perpendicular to the welding line, in this state (upper state in FIG. 10A),
Since the optical axis plane of the distance sensor 30 is parallel to the scanning direction, the sensor unit 30 is mounted around the welding torch 10 at 90 degrees.
The optical axis plane is rotated at a right angle to the scanning direction.

Also in FIG. 10 (b), since the scanning direction of the sensor unit 30 is a direction perpendicular to the welding line,
In this state (upper side in FIG. 10B), the optical axis plane of the distance sensor 30 is parallel to the scanning direction, so the sensor unit 30 is rotated around the welding torch 10 by 90 degrees, The optical axis plane should be perpendicular to the scanning direction.

Here, at the time of sensing by the distance (displacement) sensor 31, as shown in FIG. 15 (a), the case where the projection axis is incident at a right angle to the object, and as shown in FIG. In some cases, the projection axis is incident on the object at an angle, but in any case, the measured distance is the shortest distance between the sensor 31 and the object. That is, in the case of FIG. 15A, the length of the dashed-dotted line is measured, and in FIG. 15B, the length of the projection axis is measured. Therefore, a vector parallel to the dashed-dotted line in FIG. 15A or the projection axis in FIG. 15B is considered, and the direction of this vector is defined as the distance (displacement) detection direction.

Further, in the example shown in FIGS. 10 (a) and 10 (b), as shown in FIG. 16 (a), scanning is performed with the optical axis surface of the distance sensor 31 perpendicular to the object. In the case of sensing a corner or the like, the optical axis plane of the distance sensor may be inclined with respect to the object as shown in FIG. 16 (b). Therefore, when such a situation is taken into consideration, when the sensor unit 30 performs sensing, the optical axis plane determined by the light projecting axis and the light receiving axis of the sensor unit 30 is determined by the distance detection direction and the scanning direction. It may be rotated about the axis of the welding torch so as to be at a right angle to the light cutting plane (plane parallel to the paper surface in FIG. 16).

The scanning direction of the sensor unit 30 is
As shown in FIG. 8 above, it is determined in advance in consideration of the shape of the work, the type of welding, and the like.

Next, the robot is driven to scan the sensor unit 30 in the scanning direction to obtain distance data regarding the welding line (step 140). The distance data detected by the sensor unit 30 is input to the sensor controller 50 and processed by the sensor controller 50 to obtain position and shape data regarding the welding line (step 150).

When the above-described sensing procedure is executed for a plurality of welding lines and the sensing is completed (step 160), the sensor unit 30 moves to the sensor base 4.
At 0, it is detached from the welding torch 10 and stored in the sensor base 40 (step 170).

The sensor controller 50 creates a welding job based on the position and shape information of the welding line obtained by such sensing, and transfers the created welding job to the robot controller 60. The robot controller 60 drives the robot 1 based on the transferred welding job to execute an actual welding operation.

The attachment / detachment of the sensor unit 30 is not limited to the clamp mechanism as in the above-mentioned embodiment, but other attachment / detachment mechanism such as a mechanism using magnetic force or an appropriate lock mechanism may be adopted. Further, an appropriate shape other than the cylindrical shape may be adopted depending on the attaching / detaching mechanism that also adopts the shape of the hollow shaft 12 surrounding the welding torch 10.

Further, although the present invention is applied to the welding robot in the above embodiment, the present invention is applied to a robot equipped with an appropriate processing tool for executing processing other than welding. Good.

[0084]

As described above, according to the present invention,
The sensor unit is detachable, the sensor unit is clamped to the robot only during sensing, and a hollow shaft that rotates around the robot's processing tool is provided, and this hollow shaft is rotationally driven by the rotating mechanism mounted on the tool bracket. Since the hollow shaft is configured to be gripped by the clamp mechanism provided on the sensor unit side, the sensor unit protection mechanism at the time of welding is not required, and the device configuration can be made smaller and lighter. Interference can be minimized, and the types of work that can be sensed can be expanded.

Further, according to the present invention, the postures of the processing tool and the robot during the sensing work are made to be exactly the same as those postures during the working work, and the optical axis plane of the distance sensor is always set to the predetermined posture during the sensing work. Since the azimuth angle around the torch axis of the sensor unit is controlled so as to be substantially perpendicular to the scanning direction, highly accurate sensing work can be performed without being influenced by the tip stop error while suppressing interference with the work.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the vicinity of a welding torch according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram when the present invention is applied to a welding robot.

FIG. 3 is a side view showing the vicinity of a welding torch and a sensor unit according to the embodiment of the present invention.

FIG. 4 is a plan view showing a state in which a sensor unit approaches a sensor base.

FIG. 5 is a plan view showing a state immediately after the sensor unit is set on the sensor base.

FIG. 6 is a plan view illustrating a state where the sensor unit is locked to the sensor base.

FIG. 7 is a side view showing a procedure for attaching / detaching the sensor unit to / from the sensor base and the robot.

FIG. 8 is a diagram illustrating a scanning direction during sensing.

FIG. 9 is a flowchart showing an operation example at the time of sensing.

FIG. 10 is a diagram showing the rotation operation of the sensor unit during sensing.

FIG. 11 is a diagram showing the relationship between the optical axis surface of the optical distance sensor and the scanning direction.

FIG. 12 is a diagram showing a state in which light cannot be received due to a step in the optical distance sensor.

FIG. 13 is a diagram showing a state in which the optical distance sensor has two different postures with respect to the moving direction of the measurement object.

FIG. 14 is a diagram showing output voltage characteristics when the optical distance sensor is set in two different postures.

FIG. 15 is a diagram showing a distance measurement mode by an optical distance sensor.

FIG. 16 is a diagram showing two different postures when a distance is measured by an optical distance sensor.

[Explanation of symbols]

 1 ... Welding robot 2 ... Luggage platform 3 ... Arm 4 ... Wrist 5 ... Torch bracket 10 ... Welding torch 11 ... Motor 12 ... Hollow shaft 20 ... Work piece 30 ... Sensor unit 31 ... Distance sensor 32 ... Clamp mechanism 40 ... Sensor base 50 ... Sensor Controller 60 ... Robot controller

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B25J 9/22 B25J 9/22 Z 19/04 19/04 G01C 3/00 G01C 3/00 A

Claims (5)

[Claims] 1. A sensor unit equipped with a sensor for measuring the position and shape of a machining work line in a non-contact manner is mounted in the vicinity of a machining tool of a robot, and the robot is driven before actual machining work to perform machining by the sensor unit. In a machining work line detection device for a robot that performs a sensing operation of a work line, a hollow shaft that surrounds the machining tool of the robot and rotates around the machining tool and a tool bracket to which the machining tool is attached are provided. The robot is provided with a rotation mechanism that rotationally drives the hollow shaft, and the sensor unit is provided separately from the robot, and a clamp mechanism that holds the hollow shaft of the robot is provided in the sensor unit. The hollow mechanism of the robot is clamped by the clamp mechanism of the sensor unit, and the actual machining operation is performed. Occasionally, a clamping mechanism for the sensor unit and a control means for controlling the robot to detach the sensor unit from the robot are provided, and the sensor unit is detachable from the robot and when the sensor unit is gripped by the robot. A machining work line detection device for a robot, wherein a sensor unit is rotatable around the tool axis by rotation of the hollow shaft. 2. The robot according to claim 1, wherein a sensor base for removably supporting the sensor unit is provided within a moving range of the robot, and the sensor unit is used to attach and detach the sensor unit to and from the robot. Processing work line detection device. 3. The clamp mechanism of the sensor unit is in an unclamped state in which the cylindrical shaft of the robot is released when the sensor unit is supported by the sensor base, and the sensor unit moves from the sensor unit base to the sensor unit. 3. The processing line detecting apparatus for a robot according to claim 2, wherein the apparatus is in a clamped state for gripping the cylindrical shaft when in the detached state. 4. The sensor of the sensor unit is a distance sensor for measuring a distance to a work by triangulation using light, and the robot has an optical axis plane of the distance sensor in a distance detection direction of the distance sensor. And a rotation control means for driving the rotation mechanism to rotate the sensor unit around the processing tool so as to be substantially perpendicular to the light cutting plane determined by the sensing scanning direction of the distance sensor. Characteristic robot processing work line detection device. 5. A sensor unit including a distance sensor that measures a distance to a work by triangulation using light is mounted near a machining tool so as to be rotatable around the machining tool of a robot, and before actual machining work. A machining work line detection device for a robot, which measures the position and shape of a machining work line by sensing and scanning the machining work line with the movement of a robot, wherein the robot and the sensor are as follows during the sensing. A method for controlling a machining work line detection device for a robot, characterized by controlling a unit. (a) The postures of the robot and the machining tool are set to be the same as the postures of the robot and the machining tool at the time of actual machining which are preset with respect to the machining work line. (b) Rotate the sensor unit around the processing tool so that the optical axis plane of the distance sensor is substantially perpendicular to the light cutting plane determined by the distance detection direction of the distance sensor and the scanning direction of the distance sensor. Rotate to. (c) After the rotation of the sensor unit is completed, the robot is driven to scan the sensor unit in the predetermined scanning direction.