JPH03181812A - Rotary scanning type distance sensor - Google Patents

Abstract

PURPOSE:To improve the reliability for measuring the distance by using the distance data from a photodetecting element and the scanning/rotating position data of a rotating amount detector as the triangulating data. CONSTITUTION:A light emitting element 14 and a light receiving element 18 are kept in a housing 12 with a predetermined distance. The detecting light from the element 14 is irradiated to a surface W to be detected through a condensing lens 16. The reflecting light is received by the element 18 through a focus lens 20. The receiving position of the element 18 is changed in accordance with the change of a distance L between the lens 20 and the surface W. A signal of the distance data showing the distance L is sent out from the element 18. When the housing 12 is rotated around an axial center of a shaft 22 by a driving motor 36, the detecting light from the element 14 is turned around the axial center of the shaft 22 and therefore the detecting light is rotated and scanned. In other words, the distance data fed from the element 18 and the scanning position data of a rotating position detector 38 of the motor 36 are obtained, making it possible to obtain three-dimensional data of each measuring point along the scanning locus on the surface W according to the triangulation principle. The measuring data is analyzed through a controlling part 40.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention irradiates an inspection light onto a surface to be inspected, scans the inspection light along a predetermined trajectory, and receives the inspection light with a light receiving element. Regarding scanning distance measuring sensors that measure distance by obtaining triangulation data from scanning position data and distance data from the reflecting surface to the light receiving surface, in particular, rotation scanning is performed by rotating and scanning the inspection light around a fixed axis. The present invention relates to a rotary scanning distance measuring sensor that obtains scanning position data along a trajectory and is applied to arc sensors of industrial welding robots.

[Prior art]

There are cases where the distance to a processing position of a workpiece or the like is detected by a distance sensor and the processing tool is positioned with respect to the processing position. For example, when positioning an arc welding torch, which is the end effector of an industrial welding robot, at each successive welding point on a workpiece to be welded, an arc welding sensor has traditionally been used to detect the weld line to be welded. There is.

The conventional arc welding sensor used in this industrial welding robot is equipped with a light emitting element and a light receiving element in the detection part of the arc welding sensor attached to the welding torch, and the light emitting element is crossed with the welding line by an appropriate scanning device. It has a configuration in which scanning position data is obtained from the scanning device by scanning displacement in the direction, and distance data is obtained from the light receiving element, and light is received according to the triangulation principle from these scanning position data and distance data. Measure the distance from the light-receiving surface of the element to the welding position, and add a predetermined distance between the light-receiving element and the arc generation position at the tip of the torch to the measured distance data to obtain accurate distance data between the welding torch and the welding position. is determined, and the position of the torch is controlled by movable parts such as a robot arm and wrist according to the distance data to perform the desired welding work. Here, the structure and operation of a conventional arc welding sensor will be explained with reference to block diagrams shown in FIGS. 3 and 4.

Referring to FIG. 3, this conventional arc welding sensor 1
00 is a light emitting element 1 that emits inspection light inside the housing 102
04. A lens 106 that collects the inspection light from the light emitting element 104, an oscillating mirror 112 that directs the inspection light that has passed through the lens 106 toward the test surface W, and focuses the test light reflected from the test surface W. A light-receiving element 108 that transmits light through a lens 110 and receives the light, and a galvanometer scanner that scans the swinging mirror 112 along a linear trajectory, for example.
Scanning device 1 formed by a resonant scanner etc.
14. From the amount of movement of the scanning device 114, the oscillating mirror 11
Scanning position data detector 1 that sends out scanning position data of 2
16 is incorporated into the housing 102.
is adapted to be attached to the torch section of an industrial welding robot by means of a coupling bracket (not shown). Here, since the above-mentioned light receiving element 108 receives the inspection light from the surface W to be inspected via the focus lens 110 arranged at a fixed position, the distance between the lens 110 and the surface W to be inspected is small. It functions as a distance data detection means that sends an electric signal corresponding to the distance.

The arc welding sensor 100 having the above-described configuration is coupled to a control device 120, which controls the scanning command unit 1.
22, is equipped with a scanning position data receiving section 124, a distance data receiving section 126, a comprehensive position data receiving/transmitting section 128, etc., and the scanning position data of the scanning position data detector 116 and the distance data of the light receiving element 108 are The data is coupled to the scanning position data receiving section 124 and the distance data receiving section 126. The control 1120 sends the above-mentioned scanning position data and distance data to the comprehensive position data receiving/transmitting unit 128.
In this step, distance measurement data in three-dimensional space at each measurement point on the surface to be inspected W is calculated and detected by the triangulation method, converted into comprehensive data, and sent to an analysis device.

The analysis device calculates and detects the position of the weld line based on the comprehensive data and transmits it to the welding robot's control device. Therefore, the robot control device adds and corrects the preset distance between the torch and the sensor 100 based on the detected distance measurement data, and directs the torch nozzle to each measured point. This control operation is realized in online control of the robot by measuring the distance of each measurement point on the surface to be inspected in advance.

Conventional arc welding sensor 100 shown in FIG. 3 above
is fixedly attached to the torch of a welding robot using a coupling bracket. However, since it is fixedly attached, it is fine if the desired welding direction is perpendicular to the scanning direction, but it is better to weld parallel to the scanning direction. If the direction changes, etc., the weld line will no longer be visible. To this end, another conventional arc welding sensor 200 shown in FIG.
02 is connected to a separately provided rotary drive mechanism 202, and this rotary drive mechanism 202 connects an electric motor 206 equipped with a rotational position detector 204 such as a rotary encoder to an arc welding sensor 200 via a transmission mechanism 208 such as a gear mechanism. The arc welding sensor 200 is configured to be rotatable relative to the torch of the welding robot, so that when the field of view is limited by the scanning direction conditions described above, the arc welding sensor 200 is rotated around the torch to secure the field of view, and then, This sensor is designed to perform a distance measurement function in the same way as the arc welding sensor 100 shown in FIG. At this time, the control unit 120 includes a rotation command unit 130 that issues a rotation command to the electric motor 206 to a position where the field of view is secured according to the field of view restriction, and a rotation amount data of the sensor 200 from the rotation position detector 204 of the electric motor 206. A rotation position data receiving section 132 is provided which receives the rotation amount data and sends the rotation amount data to the comprehensive position data receiving and transmitting section 128. That is, the configuration is such that the amount of rotation of the sensor 200 can be corrected during calculation and detection of comprehensive position data.

[Problem to be solved by the invention]

However, the two arc welding sensors 100 described above
200 is a method in which the inspection light is scanned by the scanning device 114. Therefore, there is a delay in the actual scanning operation with respect to the scanning command, and a mechanism (scanning position data detector 116) that detects the amount of delay is required. Therefore, these mechanisms impede miniaturization and simplification of the arc welding sensor itself, and there is a problem that adversely affects the operating function of the torch. In addition, since the scanning device 114 always has a mechanically movable part as a mechanism for swinging the swinging mirror 112, external shocks caused by contact with external equipment that occur during robot operation and acceleration/deceleration of the robot itself may occur. It is weak against shock, etc., and therefore has the disadvantage of lacking functional reliability.

Furthermore, in the arc welding sensor 200 shown in FIG.
Since a method is adopted in which the rotational position data from the rotational drive mechanism 202 is corrected and added to the comprehensive position data at the creation stage, there is more room for errors to intervene, and errors included in the scanning position data, distance data, etc. Due to the cumulative error, there is also the disadvantage that the resolution decreases in terms of the performance of obtaining distance measurement data.

Therefore, the present invention can solve the above-mentioned conventional drawbacks, and can be used not only as a distance measuring sensor for the torch of an arc welding robot, but also for various well-known industrial robots that perform material cutting, deburring work, sealing work, etc. It is an object of the present invention to provide a scanning distance measuring sensor that can be attached to a vehicle.

Another object of the present invention is to rotate the sensor housing from the outside, in which the test light emitting element and the test light receiving element are fixedly incorporated, without performing the scanning operation of the test light by incorporating a complicated scanning device. An object of the present invention is to provide a rotary scanning type distance measuring sensor that scans an inspection light along a circular locus on a surface to be inspected when operated.

[Means to solve the problem]

In view of the above-mentioned object of the invention, the present invention has a light-emitting element for emitting inspection light and a light-receiving element for receiving reflected inspection light from a surface to be inspected, which are fixedly held in a housing, and the housing is moved along a constant axis by a drive motor. The scanning action of the inspection light is achieved by reciprocating rotation around the periphery, and the drive motor is formed by an electric motor equipped with a rotational position data detector, and the scanning position data is detected from the rotational position data detector. This is then combined with distance data obtained from the light-receiving element to obtain distance measurement data for each measurement point.

That is, according to the present invention, the light-emitting element that emits detection light and the light-receiving element that receives the reflected light of the detection light from the surface to be measured are provided, and measurement from a fixed point to each measurement point on the surface to be measured is performed. A rotary scanning distance measuring sensor for obtaining distance triangulation data, comprising a sensor holding means for attaching and holding the light emitting element and the light receiving element at fixed fixed positions separated from each other, and a purple sensor holding means for rotatably holding the light emitting element and the light receiving element. a rotating shaft that scans and rotates the sensor holding means around the rotating shaft and is equipped with a detector for the amount of rotation thereof; The present invention provides a rotary scanning type distance measuring sensor, which is configured to include a bracket having a bracket, and converts distance data from the light receiving element and scanning rotational position data of the rotational amount detector into distance measuring triangulation data. be. Thereby, the configuration of the control section coupled to the distance measuring sensor can also be simplified. Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.

〔Example〕

FIG. 1 is a block diagram showing the basic configuration of a rotary scanning distance measuring sensor according to the present invention and its connection relationship with a control section.
The figure is a perspective view showing the specific structure of the sensor.

1st r! ! Referring to Fig. J, the rotary scanning distance measuring sensor 10 according to the present invention has a housing 12 in which a light emitting element 14 and a light receiving element 18 are fixedly arranged with a predetermined distance between them. Retained. The light emitting element 14 is attached, for example, in a fixed tilted posture as shown in the figure, so as to irradiate the inspection light onto the surface W to be inspected via the condensing lens 16. On the other hand, the light receiving element 18 is provided so as to receive the inspection light reflected from the surface W to be inspected via the focus lens 20. At this time, since the distance between the light receiving element 18 and the focus lens 20 is set to a fixed distance, the light receiving element 18
The light receiving position of 8 changes. Therefore, the light receiving element 18 sends out a distance data signal indicating the distance "L" each time it changes.

On the other hand, according to the invention, the sensor housing 12 is connected to the shaft 2
2, and is rotatably held in the housing 32 of the rotary drive device 30, and is coupled to a drive motor 36 via a suitable transmission mechanism 34, such as a gear mechanism or a belt boolean mechanism. is configured with a rotational position detector 38. That is, the drive motor 36 and the rotation detector 38 are formed by electric servo motors equipped with a well-known rotary encoder. Therefore, when the sensor housing 12 is rotated around the axis of the shaft 22 by the drive motor 36, the inspection light emitted from the light emitting element 14 will rotate around the axis of the shaft 22, and the inspection light will have a rotational scanning effect. will receive. At this time, the scanning amount, that is, the scanning position data, is the position detection data of the rotational position detector 38 provided in the drive motor 36 directly forming the scanning position data. In other words, the distance data sent from the light receiving element 18 and the scanning position data of the rotational position detector 38 of the drive motor 36 are obtained, and both of these data are scanned on the surface W to be inspected using the triangulation principle. It is possible to measure the three-dimensional position data of each measurement point along the trajectory.

The sensor 10 is coupled to a control section 40, which has substantially the same function as the conventional control section 120 (FIGS. 3 and 4), but uses distance data from the light receiving element I8. a distance data receiving section 42 that receives the rotation command signal, a rotation command section 44 that sends a rotation command signal to the drive motor 36, a scanning position data receiving section 46 that receives rotational scanning position data from the rotational position detector 3B, and a scanning position data receiving section 46 that receives the rotational scanning position data from the rotational position detector 3B. The integrated position data receiving/transmitting unit 48 of the control unit 40 is sent to an analysis device (not shown). ) is sent to the rotary drive device 3 for analysis, which is the same as before.
When the sensor housing 12 is rotationally driven by 0, for the purpose of scanning the inspection light, a reciprocating rotation operation is performed to rotate the sensor housing 12 at each measurement point on the test surface W (for example, from the center point of a torch in an arc welding sensor to the test surface). The test surface is rotated 360° around a predetermined reference point (the intersection of the straight line and the test surface). As a result, two-dimensional shape data (coordinate values in the orthogonal coordinate system on the plane) of the trajectory on the surface to be inspected W is obtained from the position data of the rotational scanning trajectory, and the distance from each point on the trajectory to the focus lens 20 is obtained. Obtain "L". and,
From such two-dimensional shape data and distance data, an analysis device calculates and detects the three-dimensional coordinate values of each of the measurement points to obtain distance measurement data.

FIG. 2 shows the structure of a specific embodiment when used as an arc welding sensor using a torch of a welding robot.

In FIG. 2, the housing 12 of the rotary scanning distance measuring sensor 10 is shaped like a box, and the sensor lO is attached to the shaft 2 with respect to the bracket 32' that encloses the housing of the drive device 30.
2 through a bearing 35, and is therefore rotatably operated by a drive motor 36 through a transmission mechanism 34 that is separated from the belt-boot mechanism. The drive motor 36 is formed of an electric servo motor with a rotary encoder or the like, as described above, which has a rotation detector 38. Further, a welding torch 5 is attached to the shaft 22.
0 is attached, and this torch 50 is the workpiece (surface to be inspected) W.
When performing a welding operation along welding line "A" or "B", sensor 10 measures the coordinates of each point on welding line "A" or "B".

The bracket 32° is provided with a mounting portion 33 for connection to a robot.

The rotary scanning distance measuring sensor 10 having such a structure can be easily attached to a suitable position on the body of an industrial welding robot via the attachment part 33 and used. It goes without saying that the distance measuring sensor 10 of this embodiment operates according to the distance measuring principle described above with reference to FIG.

As is clear from the above description, the rotary scanning distance measuring sensor according to the present invention differs from the conventional one in which the inspection light from the light emitting element is scanned along a straight path in an oscillating manner. The light-emitting element and the light-receiving element, which are held in a fixed position, are mounted by rotating the light-emitting element and the light-receiving element together around a fixed axis, thereby imparting a scanning effect to the inspection light from the light-emitting element. Note that the rotary scanning distance measuring sensor 10 shown in FIG. 2 is not only used as an arc welding sensor for the torch of a welding robot, but also for other purposes such as
Needless to say, it can also be used as a sensor for measuring the sealing position by a seal gun of a well-known seal robot or the laser beam irradiation position of a laser beam emitting gun of a laser robot.

〔Effect of the invention〕

According to the present invention, as is clear from the above description, instead of providing a swing scanning device inside the sensor itself, the holding means holding the fixed light emitting element and the light receiving element is rotated to perform scanning of the inspection light. As a result, the conventionally required scanning device (scanning device 114 in FIGS. 3 and 4) is no longer necessary, and the sensor part containing the light-emitting element and light-receiving element can be miniaturized, making it possible to reduce the size of the sensor with a built-in light-emitting element and light-receiving element. This has the advantage of not interfering with the action of In addition, since the rotational position detector (equipped in the drive motor) of the rotary drive device sends out the scanning position data, there is no need for a detector for scanning position data, and since there is no accumulation of errors, the resolution of the sensor can be improved. This has the effect of improving the Furthermore,
This eliminates the need for a scanning device that is susceptible to functional deterioration due to external shocks, etc., and can also provide the effect of improving the reliability of the distance measurement function of the distance measurement sensor. As a result, it can also contribute to improving the operational accuracy of machines such as welding robots and other industrial robots.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of the rotary scanning distance measuring sensor according to the present invention and the connection relationship between the control unit and the controller.
The figure is a perspective view showing the specific structure of the sensor, Figure 3 is a mechanical block diagram showing an example of the first method of a conventional scanning distance measuring sensor, and Figure 4 is an example of the second method. The mechanism block diagram shown in FIG. DESCRIPTION OF SYMBOLS 10...Rotary scanning distance sensor 12...Housing, 14...Light emitting element, 18...Light receiving element, 20
... Focus lens, 22... Axis, 30... Drive device, 36... Drive motor, 38... Rotational position detector.

Claims (1)

[Claims] 1. A light-emitting element that emits detection light and a light-receiving element that receives the reflected light of the detection light from the surface to be measured, and is capable of measuring from a fixed point to each measurement point on the surface to be measured. A rotary scanning distance measuring sensor for obtaining distance triangulation data, comprising: a sensor holding means for attaching and holding the light emitting element and the light receiving element at fixed fixed positions separated from each other; and a rotatable holding means for holding the sensor holding means. a rotational shaft for rotating the sensor holding means around the rotational shaft; a rotational driving means for rotationally scanning the sensor holding means around the rotational shaft and having a detector for the amount of rotation thereof; What is claimed is: 1. A rotary scanning type distance measuring sensor, comprising: a bracket, wherein the distance data from the light receiving element and the scanning rotation position data of the rotation amount detector are used as distance measuring triangulation data. 2. The rotary scanning distance measuring sensor according to claim 1, wherein the attachment part of the bracket is an attachment part to a torch of a welding robot, and the arc emission point of the torch is the fixed point. 3. The rotary scanning distance measuring sensor according to claim 1, wherein the rotational drive means comprises an electric motor equipped with a rotary encoder.