DE102010038902A1 - Method and device for supporting the training of a hand welder - Google Patents

Abstract

The invention relates to a method and a device for supporting the training of a hand welder by recording and evaluating the manually performed movements of a hand welding torch in connection with a low current arc on training workpieces, the recording of the hand welding torch speed and hand welding torch orientation in the working space by means of a contactless measurement technology based on an image processing technique happens in which, together with the low-current arc, optically recognizable features of the manual welding torch are recorded by an electronic camera in the form of luminous light spots. Essential features of the invention are that, in particular, only one camera from any arrangement to the working area of the hand welder simultaneously detects the positions of the burning low-current arc and of additional light sources on the hand welding torch, that the geometry of the training workpieces is recorded once in the coordinate system of the camera via calibration, during that the welding torch movement from the position of the low-current arc in the camera image calculates the coordinate of the same as the position on the training workpiece and that the unique orientation of the manual welding torch in the room is determined from the positions of the light points of the light sources in the camera image in conjunction with knowledge of the current position of the low-current arc in the room .

Description

The invention relates to a method and a device implementing the method for supporting the training of a hand welder by means of a detection and evaluation of manually performed movements of a manual welding torch, which is used with a low-voltage arc on training workpieces, the recording of the hand welding torch speed and manual torch orientation in the working space by a non-contact , Is carried out based on an image processing technology measurement technique, and recorded together with the arc optically recognizable features of the welding torch in the form of bright points of light from an electronic camera.

It is well-known that the training and the training of the skills of a hand welder is a complex process, which requires a lot of practice time, a comprehensive care by qualified personnel, a suitable equipment technology and various consumables. This experience led early to the development of auxiliary equipment, which should improve the effectiveness of training, for example, in the patent US 23333192 already described a solution in which according to the basic principle of the simulation of a consumable electrode, a modified electrode using Kontaktgaben with a base plate with correct electrode guide the trainees on the switching on of a lamp shows a burning arc. The core elements of many solutions are simulations as a substitute for the real welding process as well as displays for the achieved results such as correct welding torch retention or feed rate. In the DD 99245 For example, a welding trainer is described in which a control unit with electric actuators simulates the erosion of the electrode via a relay control. In DE 3101890 A comparable solution is described in which a metal electrode in the welding torch is retracted and a lamp imitates the burning of an arc. A further development of this principle shows the CN 2071999 , In this imitator for Training Welder a micromotor-driven telescopic rod replaces the consumable electrode.

All of these solutions have the disadvantage that the training devices behave with their mechanical aids clearly different than a real arc, the transferability of the experience of these contact devices on a "non-contact" burning arc is therefore not sure.

Therefore, solutions have been developed that minimize this disadvantage. In the Device for Tesching and Evaluating a Persons Skill as a Welder US 4124944 The simulated movements are recorded with magnetic sensors. Similarly, in the device for training and evaluation of welding skills after CA 1109253 using a magnet as an arc substitute and receivers analyzing its magnetic field, determining the torch position. In CN 1249974 A high-frequency pulse simulates the welding arc.

Despite the intended contactlessness of the stick electrodes or welding torches, these training devices are not comparable in their handling with the experiences that a burning arc would impart. Also solutions that are based on modern electronics / computing technology, such. B. the device for training welders US 4931018 where the function of a CRT monitor is used to support a simulated motion, the Virtual Trainer from DIGINEXT (Prospectus), where a welding torch motion is simulated on a computer screen or the EWI Virtual Reality Welder Training System (prospectus), in which the hand of the welder and the welding torch are equipped with 6-dimensional detection systems and the results of a simulated welding are shown to the operator in a virtual environment on screens in glasses, do not replace the constraints, feelings and experiences when dealing with a burning welding arc.

It is precisely for this reason that solutions for assisting welding training have been developed, which use a burning arc and more or less explain the results of his manual skills to the trainee. In DD 212344 For example, it is described that from the sound noise of the welding arc, an acoustic signal about the quality of the welding process is generated, which is supplied to the welder via headphones. This sound noise is related to the energetic process of the arc, although important details of the welding torch movement, such as the angle of attack and feed, that are essential for welding training can not be deduced from the noise.

A welding trainer for manual welding after RU 2373040 analyzes the welding movement, ie the welding torch advance from the detection of a current distribution on the component by taking the partial currents at the ends of the welding path. For the detection of the angle of attack more angle-giving sensors on the burner holder are required. A major disadvantage of this solution is that the detection of a power split comparatively insensitive and dependent on many confounding factors such as contact properties. For the measurement of the angle of attack additional systems are required.

A further development of this solution is the Computer Based Welding Training System of the Sakol Teeravarunyou and Bovornchok Poopatb School, Bangkok (International Journal of Industrial Engineering, 16 (2), 116-125, 2009.). The training system measures the arc length from the electrical parameters and all electrode movements (feed, 2 angles) via a mechanical linkage on the electrode holder with a Memsic transducer and an analog distance sensor. The results of the motion analysis are fed to the trainee via a voice output. A disadvantage of this solution, which is in itself comfortable, is that the welding torch / electrode holder is again coupled with mechanical auxiliary rods which limit the usual handling of a welding torch.

In the JP2004090041 For example, an apparatus and method for assisting hand welding and training are described in which the arc length is detected with "information-gathering optical means" and derived therefrom information provided via voice output to the welder to assist the welding movements. Here, the advantage of non-contact information acquisition is given details of the burner movement as attack angle in space, however, are disregarded in this solution.

In US 20090298024 a Welding Training System is described with many of the prior art components, the position detection of the welding torch is to take place via a combination of an acceleration sensor and a Kreiselmessprinzip. Essential components of the invention relate to the transmission of the results to the welder, which should be done in particular by visual systems or a tactile solution (vibrator). With regard to the position detection of the manual welding torch via gyroscope and acceleration sensors, it should be remembered that these output differentiated signals of the position variables each time. For recalculation to absolute positions, integration procedures are required, which are known to be relatively expensive and inaccurate. The requirements for an objective evaluation of a temporally longer welding movement, these solutions do not do justice.

The statements on the prior art can be seen that despite the variety of approaches to support and objective assessment of manual skills of a welder - especially to support the welding training - no development is present, with the contact in a defined workspace when using a real arc the orientation and movements of the manual welding torch / electrode holder can be reliably detected and evaluated.

The invention thus has the aim of overcoming the described disadvantages of the prior art and to provide a method and apparatus for assisting the formation of a hand welder by detecting and evaluating the manual movements of a manual torch in conjunction with a low current arc on reusable practice workpieces.

It is therefore an object of the invention to develop a method and a device for non-contact measurement of the angle of incidence of a manual welding torch and the effective welding torch feed movement including the realized trajectory, which under the conditions of a real arc and without additional components on the manual welding torch affecting the handling can provide safe, unique and mathematically evaluable via a connected computing technique motion data, the inclusion of the manual welding torch movement and the manual welding torch orientation should be done in a defined workspace by means of a non-contact measurement.

• – dass insbesondere nur eine Kamera aus einer beliebigen Anordnung zum Arbeitsgebiet des Handschweißers gleichzeitig die Positionen des brennenden Niederstromlichtbogens und von zusätzlichen Lichtquellen, die mit dem Handschweißbrenner in Wirkverbindung stehen, erfasst, indem unter Nutzung optimierter Filter- und Rechentechnik ausschließlich diese Lichtquellen ohne weitere Bildmerkmale selektiv aufgenommen und deren Positionen im Koordinatensystem der Kamera bestimmt werden,
• – dass einmalig über eine Kalibrierung der Kamera die Positionierung des Übungswerkstückes im Koordinatensystem der Kamera erfasst wird, wobei hierfür ein Kalibrierkörper eingesetzt wird, der im Kalibrierverfahren mit Hilfe der Aufnahme des Übungswerkstückes positioniert wird und er selbst eine dreidimensionale, geometrisch präzise und mathematisch eindeutig beschreibbare Anordnung von mehreren Lichtquellen vergleichbarer optischer Eigenschaften besitzt, und wobei aus der verzerrten Abbildung der Lichtquellen des Referenzkörpers im Kamerabild eindeutig und präzise die Positionierung der Kamera relativ zur Position des Übungswerkstückes berechnet wird,
• – dass die Oberfläche des Übungswerkstückes mit Bezug auf dessen Positionierung mathematisch beschrieben wird,
• – dass während der Schweißbrennerbewegung aus der Position des Lichtbogens im Kamerabild als tiefster Lichtpunkt im Kamerabild über elementare mathematische Transformationen die Koordinate des Lichtbogens als Position auf der mathematisch beschriebenen Oberfläche des Übungswerkstückes berechnet wird,
• – dass aus den Positionen der Lichtpunkte der zusätzlichen Lichtquellen am Handschweißbrenner im Kamerabild in Verbindung mit der Kenntnis der aktuellen Position des Lichtbogens auf der Oberfläche des Übungsteiles die eindeutige Orientierung des Handschweißbrenners im Raum ermittelt wird, wobei aus der Darstellung des Lichtpunktemusters im Kamerabild in Verbindung mit der Kenntnis der festen geometrischen Anordnung der Lichtquellen zueinander eine mathematische Schwerpunktgerade im dreidimensionalen Raum gebildet wird, die an der ermittelten Position des Lichtbogens die mathematisch beschriebene Oberfläche des Übungswerkstückes kreuzt,
• – dass während der Schweißbrennerbewegung durch die Auswertung der zeitlichen Folge der Kamerabilder unter Echtzeitbedingungen die Bahn der Schweißbrennerbewegung einschließlich der momentanen Schweißgeschwindigkeit und der Veränderungen der Handbrenneranstellwinkel normiert und im Koordinatensystem des Übungswerkstückes gebildet und einer nachfolgenden Auswerte- und Bewertungseinheit zugeführt wird.

The stated object is achieved on the basis of known components of image processing with punctiform light sources and appropriate camera technology according to the method,

• - That in particular only a camera from any arrangement to the work area of the manual welder simultaneously detects the positions of the burning low-voltage arc and additional light sources, which are in operative connection with the hand welding torch, by using optimized filtering and computing technology exclusively selects these light sources without further image features recorded and whose positions are determined in the coordinate system of the camera,
• - That once a calibration of the camera, the positioning of the Übungswerkstückes in the coordinate system of the camera is detected, for this purpose a calibration is used, which is positioned in the calibration process using the recording of Übungswerkstückes and he himself a three-dimensional, geometrically precise and mathematically clearly writable arrangement of a plurality of light sources having comparable optical properties, and wherein from the distorted image of the light sources of the reference body in the camera image clearly and precisely the positioning of the camera is calculated relative to the position of the exercise work piece,
• That the surface of the training work piece is described mathematically with respect to its positioning,
• During arc welding, the position of the arc in the camera image as the lowest point of light in the camera image is calculated via elementary mathematical transformations as the position of the arc on the mathematically described surface of the training workpiece;
• - That from the positions of the light points of the additional light sources on the manual welding torch in the camera image in conjunction with the knowledge of the current position of the arc on the surface of the exercise part, the unique orientation of the manual torch in space is determined, from the representation of the light spot pattern in the camera image in conjunction with the knowledge of the fixed geometric arrangement of the light sources to each other a mathematical center of gravity is formed in three-dimensional space, which crossed at the determined position of the arc, the mathematically described surface of the Übungswerkstückes,
• - That during the welding torch movement by the evaluation of the temporal sequence of the camera images under real-time conditions, the path of the welding torch movement including the current welding speed and the changes of Handbrenneranstellwinkel normalized and formed in the coordinate system of Übungswerkstückes and a subsequent evaluation and evaluation unit is supplied.

• – dass der Handschweißbrenner mit einer Gruppe aus zwei oder mehreren definiert räumlich angeordneten punktförmigen Lichtquellen mit großem Abstrahlungswinkel, vorzugsweise ultrahellen Lichtemitterdioden, bestückt ist.
• – dass der Handschweißbrenner insbesondere mit nur zwei punktförmigen Lichtquellen bestückt ist, die zusammen mit dem brennenden Schweißlichtbogen exakt auf einer gemeinsamen mathematischen Geraden liegen, die an der Lichtbogenbrennstelle die mathematisch beschriebenen Oberfläche des Übungsteiles schneidet.

In general, the design of the light sources attached to the manual welding torch can be recorded,

• - That the manual welding torch with a group of two or more spatially arranged spatially arranged point light sources with a large angle of radiation, preferably ultra-bright light emitting diodes, equipped.
• - That the manual welding torch is equipped in particular with only two point-shaped light sources, which lie together with the burning welding arc exactly on a common mathematical line which intersects the mathematically described surface of the exercise part at the arc focal point.

In the following the invention will be explained in more detail with reference to the example of a device for determining the hand welding burner movements on a flat, plate-shaped training work with reference to the accompanying drawings.

It shows:

1 : Spatial arrangement of the essential components for detecting the hand welding torch movements

A camera with lens 1 is over a rigid camera holder 2 with the work table 3 connected. The alignment takes place on the plate-shaped exercise part 4 , where it is determined by the choice of geometrical imaging components of camera with lens 1 is achieved that in addition to the actual exercise section 4 also the manual welding torch 5 in the field of vision of the camera. The hand welding torch 5 has in extension of its standard version a rigidly attached to this light source holder 6 , The light source holder 6 contains two ultra-bright light emitting diodes 7 with a large spatial radiation angle. In conjunction with the light source holder 6 is realized that both light emitting diodes 7 together with the end of the welding electrode 8th are aligned with each other so that they lie on a straight connecting line.

With this device, the following function is achieved:
The starting point for carrying out the motion analysis is the exact knowledge of the position of the exercise part 4 in the coordinate system of the rigidly arranged camera 1 , For this purpose, the spatial calibration of the camera is done 1 to the location of the exercise part 4 and thus the working space, ie the through the practice part 4 described mathematical plane is in the coordinate system of the camera 1 certainly.

During the analysis of the hand welding torch movements are used by the camera 1 with each picture the three light points of the two light emitting diodes 7 and at the end of the welding electrode 8th burning arc recorded simultaneously. Due to the camera setting and a primary image analysis, it is achieved that only the three points of light are detected and individually measured with regard to their position in the two-dimensional image of the camera. From the position data of the light points in the camera image and the knowledge of the spatial orientation of the camera 1 itself, the position of the mathematical line is determined via the three light sources in three-dimensional space. From this, the orientation of the manual welding torch is determined with known mathematical functions. From the intersection of the mathematical line with the mathematical plane of the exercise part 4 the calculation of the arc position takes place. The composition of the calculated data from series of pictures describes the course of the weld or the welding contour, and the changes in the burner setting angles are derived from the orientations of the manual welding torch. By known technical means are the Results of a comparison of these position values with setpoint settings are visualized, stored and, where appropriate, communicated to the trainee welder by acoustic signals.

With the realization of a method and a device according to the invention for non-contact measurement of the angle of incidence of a manual welding torch and the effective welding torch advance movement, including the realized trajectory, there are advantages in the form that with minimal additional components on the manual welding torch, namely a few light emitting diodes, the handling of the burner in any Negative influence, in conjunction with a single, far enough away from the intended welding area placed camera without contact and restriction-free, the spatial movements of the manual welding torch with high dynamics and precision can be completely capture.

• – Der Handschweißer erlernt die grundlegenden motorischen Abläufe mit einem realen Lichtbogen,
• – beim Schweißen werden die Hauptparameter des Bewegungsablaufes wie Schweißnahtverlauf, Schweißgeschwindigkeit, Lichtbogenlänge und Brennerwinkel kontinuierlich und mit hoher Präzision erfasst,
• – die vom Handschweißer verursachten Abweichungen werden diesem zeitnah signalisiert,
• – für die Aufnahme der Bewegungen sind nur kleine Anbauten am Handschweißbrenner erforderlich, die die Handhabung nicht einschränken,
• – das Schweißen erfolgt mit einem Niederstromlichtbogen, so dass die verwendeten Übungswerkstücke für eine große Anzahl von Übungen verwendet werden können,
• – über verschiedene Übungswerkstücke können unterschiedliche Trainingsaufgaben absolviert werden.

Advantages in the described application are:

• - The hand welder learns the basic motor processes with a real arc,
• During welding, the main parameters of the sequence of motion, such as the course of the weld, the welding speed, the arc length and the burner angle, are detected continuously and with high precision,
• - the deviations caused by the manual welder are signaled promptly,
• - For the recording of the movements only small attachments are required on the manual welding torch, which does not limit the handling,
• Welding is done with a low current arc, so that the exercise workpieces used can be used for a large number of exercises,
• - Different training tasks can be completed different training tasks.

LIST OF REFERENCE NUMBERS

1

camera

2

camera Mounts

3

worktable

4

Exercise workpiece

5

Manual welding torch

6

Light source holder

7

Light emitting diode

8th

Low current arc

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 23333192 [0002]
• DD 99245 [0002]
• DE 3101890 [0002]
• CN 2071999 [0002]
• US 4124944 [0004]
• CA 1109253 [0004]
• CN 1249974 [0004]
• US 4931018 [0005]
• DD 212344 [0006]
• RU 2373040 [0007]
• JP 2004090041 [0009]
• US 20090298024 [0010]

Claims (3)

Method for supporting the formation of a manual welder by means of a non-contact measurement of the angle of incidence of a manual welding torch ( 5 ) and an effective welding torch advance movement including a realized welding path on the basis of known components of image processing with punctiform light sources and suitable camera technology, characterized in that in particular only one camera ( 1 ) from any arrangement to the working area of the welder simultaneously the positions of the burning low-voltage arc ( 8th ) and of additional light sources which are connected to the manual welding torch ( 5 ) are in operative connection, recorded by using optimized filtering and computing technology exclusively these light sources without further image features selectively and their positions in the coordinate system of the camera ( 1 ) that once a calibration of the camera ( 1 ) the positioning of the exercise work piece ( 4 ) in the coordinate system of the camera ( 1 ) is used, wherein for this purpose a calibration body is used, which in the calibration process by means of recording the Übungswerkstückes ( 4 ) and itself has a three-dimensional, geometrically precise and mathematically clearly describable arrangement of a plurality of light sources of comparable optical properties, and wherein from the distorted image of the light sources of the reference body in the camera image clearly and precisely the positioning of the camera ( 1 ) relative to the position of the exercise piece ( 4 ), it is calculated that the surface of the exercise work piece ( 4 ) is described mathematically with respect to its positioning, that during the welding torch movement from the position of the low-voltage arc ( 8th ) in the camera image as the lowest point of light in the camera image via elementary mathematical transformations, the coordinate of the low-current arc ( 8th ) as a position on the mathematically described surface of the exercise work piece ( 4 ) is calculated from the positions of the light spots of the additional light sources on the manual welding torch ( 5 ) in the camera image in conjunction with the knowledge of the current position of the low-voltage arc ( 8th ) on the surface of the exercise work piece ( 4 ) the clear orientation of the manual welding torch ( 5 ) is determined in the room, wherein from the representation of the light spot pattern in the camera image in conjunction with the knowledge of the fixed geometric arrangement of the light sources to each other a mathematical line of gravity is formed in the three-dimensional space at the determined position of the low-voltage arc ( 8th ) the mathematically described surface of the exercise work piece ( 4 ) and that, during the welding torch movement, by evaluating the temporal sequence of the camera images under real-time conditions, the trajectory of the torch movement, including the instantaneous welding speed and changes in the torch setting angles, is normalized and determined in the coordinate system of the training workpiece ( 4 ) is formed and fed to a subsequent evaluation and evaluation unit. Device for carrying out the method according to claim 1, characterized in that the manual welding torch ( 5 ) with a group of two or more spatially arranged point-shaped light sources with a large emission angle, preferably ultra-bright light emitting diodes (US Pat. 7 ), is equipped. Device for carrying out the method according to claim 1 or 2, characterized in that the manual welding torch ( 5 ) is equipped in particular with only two point-shaped light sources, which together with the burning low-voltage arc ( 8th ) lie exactly on a common mathematical straight line, which at the arc focal point by the mathematically described surface of the Übungswerkstückes ( 4 ) leads.

Images