EP2958200A1 - Method for calibrating a mounting apparatus - Google Patents

Abstract

An insertion apparatus for automatically populating a connector housing with a contact part comprises a holder for the connector housing, a positioning device with a movable gripper for positioning the contact part and for inserting the contact part in a cavity of the connector housing, an image capture device for receiving an image of the holder and a control unit for Determining a position of the cavity in the image and determining a movement of the gripper required to insert the contact part into the cavity. To calibrate the placement device, a marking carrier is attached to the holder. By means of a gripping device gripped by the gripper, several marking points are placed on the marking carrier attached to the holder. By means of the image capture device, the positions of the marker points are determined on the marker carrier. The determined positions of the marker points are stored in a memory device.

Description

The present invention relates to a method of calibrating a mounting apparatus, which is adapted to automatically populate a connector housing with a mounted on an electrical line contact part and a holder for the connector housing, a positioning device with a movable gripper for positioning the contact part with respect to the holder and for introducing the contact part in an insertion direction into a cavity of the plug housing, an image acquisition device for receiving at least one spatially resolved image of at least a part of the holder and a control unit for determining a position of the cavity in the at least one spatially resolved image and for determining a for introducing the contact part in the cavity comprises required movement of the gripper based on the determined position of the cavity.

The machining of electrical wiring harnesses is often performed using robots or similar positioning devices equipped with grippers as end effectors. Usually, such a gripper holds a contact part either directly or on the electrical line, moves it to the desired cavity and introduces it into it. The term "plug housing" is basically a socket housing, a terminal block or the like to understand. Ensuring a reliable and efficient assembly process requires accurate knowledge of the positions of the corresponding components of the system.

For cost reasons, neither the connector housing nor the contact parts of conventional electrical cables can be manufactured with strict tolerance specifications. Accordingly, it comes in the operation of common placement devices again and again to inaccuracies in the positioning, whereby a reliable and efficient operation is difficult. An observation of the holder by means of the image capture device can only partially remedy this situation. In particular, positional deviations of the gripper, which only arise in the course of the positioning and insertion movement, can generally not be taken into account by the image capture device.

It is therefore an object of the invention, even with the use of tolerance-sensitive positioning devices, plug housings, holders and / or contact parts to allow a precise, error-free and fast placement of a connector housing with a mounted on an electrical line contact part.

The solution of this object is achieved by a method for calibrating a placement device having the features of claim 1.

1. (i) ein Markierungsträger an dem Halter angebracht wird,
2. (ii) mit dem beweglichen Greifer ein Markierungsmittel gegriffen wird,
3. (iii) mittels des Greifers und des durch diesen gegriffenen Markierungsmittels mehrere Markierungspunkte auf dem an dem Halter angebrachten Markierungsträger gesetzt werden,
4. (iv) mittels der Bilderfassungseinrichtung die Positionen der Markierungspunkte auf dem Markierungsträger ermittelt werden und
5. (v) die ermittelten Positionen der Markierungspunkte in einer der Steuereinheit zugeordneten Speichereinrichtung abgelegt werden.

According to the invention, such a method comprises the steps of

1. (i) a marking carrier is attached to the holder,
2. (ii) a marking means is gripped by the movable gripper,
3. (iii) by means of the gripper and the marking means gripped by the latter, a plurality of marking points are set on the marking carrier attached to the holder,
4. (iv) the positions of the marker points on the marker carrier are determined by means of the image capture device, and
5. (V) the determined positions of the marker points are stored in a memory device associated with the control unit.

Since the marker points are set with the same movable gripper with which the contact parts are positioned and inserted even during normal operation of the placement device, each marker point indicates exactly that position which is approached during the placement process with appropriate control of the positioning system. Deviations of the movement from a given course remain irrelevant here. Regardless of the extent to which such deviations occur and how they come about, a marking point in any case indicates the exact insertion position, which results in the corresponding control of the positioning device.

During normal operation of the placement device, the stored positions of the marker points can be interrogated and taken into account in the calculation of the required traverse movement of the gripper. By means of the calibration method according to the invention, it is thus possible to completely compensate for all mechanical tolerances and deviations of the placement device as well as the provided connector housing and contact parts in the context of the machine control. A particular advantage of the calibration method according to the invention is that it can be carried out by simple means and especially using the image capture device provided anyway.

Preferably, in step (iii) the gripper is respectively moved with spaced from the marking carrier marker in a transversely to the insertion direction traversing plane according to predetermined trajectory coordinates of the positioning device to a marking position, wherein in step (v) in each case the traversing coordinates together with the determined position of the associated marker point are stored in the memory device. The marking points are thus assigned to those traversing coordinates that underlie their creation. In the memory device are in this embodiment So not only the positions of the marker points stored themselves, but also the respective causal control parameters. After completion of the calibration process, it is then possible to proceed during normal operation of the placement device in such a way that the matching positioning coordinates or control parameters are retrieved for a given insertion position.

In step (iii), the gripper is preferably moved towards the marking carrier in the insertion direction after the gripper has reached the marking position. As a result, each marking point is set exactly at the point at which a contact part would be introduced if it were held by the gripper instead of the marking means. Thus, the positions of the marker points are directly and directly linked to insertion positions of contact parts.

An embodiment of the invention provides that, in step (iv), the positions of the marking points on the marking carrier are determined relative to a reference mark provided on the holder and detectable by the image capture device. By using such a reference mark, the positions of the marker points relative to the holder can be determined particularly precisely - even if the image capture device assumes different points of view when determining the positions of the marker points on the marker carrier in step (iv).

In step (v), the position of the reference mark can also be stored in the memory device. The stored position of the reference mark can be used as a reference for other holders.

A special embodiment of the invention provides that a reference body connected to the holder, preferably made of sheet metal, with at least one, in particular punched or lasered, recess as a reference mark provided. The recognition of a sharply bordered recess in a camera image is possible with suitable illumination with relatively high accuracy. A reference body in the form of a lasered sheet metal plate is comparatively inexpensive to produce. If necessary, the edges of the recess can be recognized from both sides of the reference body, ie independently of whether the image capture device is located in front of or behind the holder. In order to ensure a particularly reliable detection of the reference mark, an arrangement of a plurality of recesses may be provided on the reference body.

A further embodiment of the invention provides that in step (iii) the gripper is first moved to the reference mark and from there to the respective marking position. The positioning of the marking means relative to the reference mark can be checked by the image capture device. The marker points are thus related to the coordinate system of the holder.

In step (iii), the marker points may be set line by line or column by column, preferably at a uniform distance from each other. In this way, lines with spaced landmarks on the marker carrier can be created, each of which can be used similar to a scale for position determination.

In particular, in step (iii) by repeated line-by-line or column-wise setting of marking points, a grid-like dot field can be formed on the marking carrier which extends at least over a working area of the holder holding the plug housing. Such a grid-like point field can include a whole area of the holder and, if required, even the complete holder in the calibration.

Preferably, in step (i) a flat labeling medium, in particular a paper or film element, is used as the marking carrier. Such a flat labeling medium can be attached in a simple manner to a gripper facing the front of the holder. For this purpose, suitable fastening means, for example one or more clamping strips, can be provided on the holder.

In step (ii), in particular a pin, a needle, a laser head or a thermocouple can be used as marking means. The use of a pen or needle is particularly cost effective. In contrast, the use of a laser head or a thermocouple allows the setting of very fine and / or structured marking points.

A further embodiment of the invention provides that step (iii) is carried out at a loading station of the mounting device and step (iv) is carried out at a measuring station of the mounting device separate from the mounting station. The provision of a surveying station and a separate loading station is favorable in terms of process equipment with respect to a placement device. In particular, in such an embodiment, during normal operation, a contact part can be introduced, while at the surveying station already another holder is measured with connector housing. When calibrating the system, both stations can be used to advantage.

A further embodiment of the invention provides that in step (iv) the image capture device is successively moved to the individual marker points by means of a further positioning device, wherein the positions of the marker points on the marker carrier respectively from the displacement position of the further positioning system and the position of the marker point in the captured image. By the individual approach of the marking points the position determination of a marker point in the image can take place with a particularly high resolution. Likewise, due to the individual approach of the marking points, it is possible to use an image capture device with comparatively low resolution for cost savings.

It can be provided that the holder is designed to hold a plurality of connector housings, wherein in step (iii) the marking points are set such that each held connector housing at least two, preferably at least five, marker points are assigned. This ensures a sufficiently accurate consideration of any positional deviations.

The invention also relates to a mounting apparatus for automatically populating a connector housing with a contact part attached to an electrical lead, comprising a holder for the connector housing, a positioning device with a movable gripper for positioning the contact part with respect to the holder and for inserting the contact part in an insertion direction in a cavity of the connector housing, an image acquisition device for receiving at least one spatially resolved image of at least a part of the holder and a control unit for determining a position of the cavity in the at least one spatially resolved image and for determining a required for insertion of the contact part in the cavity movement of the gripper the determined position of the cavity comprises.

According to the invention, a control unit of the mounting device is designed to carry out a calibration method as described above. Such a calibration function allows a reliable compensation of all tolerances and deviations of the entire system.

Further developments of the invention are set forth in the dependent claims, the description and the accompanying drawings.

Fig. 1

zeigt eine Vermessungsstation einer erfindungsgemäßen Bestückungsvorrichtung während eines Normalbetriebs.

Fig. 2

zeigt eine Bestückungsstation einer erfindungsgemäßen Bestückungsvorrichtung während eines Normalbetriebs.

Fig. 3

zeigt die in Fig. 2 dargestellte Bestückungsstation während eines erfindungsgemäßen Kalibriervorgangs.

Fig. 4

zeigt die in Fig. 1 dargestellte Vermessungsstation während eines erfindungsgemäßen Kalibriervorgangs.

The invention will now be described by way of example with reference to the drawings.

Fig. 1

shows a surveying station of a mounting device according to the invention during normal operation.

Fig. 2

shows a placement station of a mounting device according to the invention during normal operation.

Fig. 3

shows the in Fig. 2 shown placement station during a calibration process according to the invention.

Fig. 4

shows the in Fig. 1 illustrated surveying station during a calibration process according to the invention.

In the Fig. 1 shown surveying station 10 forms the input part of a mounting device according to the invention and comprises a pallet-like holder 12 to which a plurality of connector housing 14 are fixed. The connector housing 14 may be latched, for example, in receptacles of the holder 12, optionally using additional individual brackets. On the rear sides of the connector housing 14 are each a plurality of cavities 16, in which subsequently to be described contact parts are inserted. Furthermore, a made of thin sheet metal reference plate 17, in which a plurality of recesses 18 are lasered, attached to the holder 12.

An image capture device in the form of a first camera 19 with associated image processing system (not shown) serves to receive spatially resolved images of a portion of the holder 12 including the connector housing 14 fixed thereto. The first camera 19 is on a camera positioning system 20 fixed by means of which it can be moved in front of the individual connector housings 14 positioned. In the illustrated embodiment, the camera positioning system 20 is designed as a biaxial linear system. For the sake of clarity, the holder 12 with the fixed connector housings 14 and the camera positioning system 20 are shown in a front view, while the first camera 19 itself is shown in a plan view. The holder 12, the reference plate 17, the camera positioning system 20 and the first camera 19 are associated with respective coordinate systems, which in Fig. 1 shown as arrow arrangements and designated by the reference numerals 61-64.

In the Fig. 2 shown placement station 24 is associated with the same placement device as in Fig. 1 shown surveying station 10 and this is preferably downstream of process engineering. The in Fig. 1 shown holder 12 can be transported including the fixed connector housing 14 by means of a transport system not shown to the loading station 24. At the loading station 24, a second camera 26 is provided including an image processing system, not shown. The camera 26 shown in plan view is disposed behind the holder 12 shown in front view - ie on the side facing away from the cavities 16 - in the region of the reference plate 17 so that it has the recesses 18 of the reference plate 17 in view. In front of the holder 12 are two grippers 28a, 28b, which are combined to form a double gripper and movable by means of a gripper positioning system 30. The coordinate system 65 of the second camera 26 and the coordinate system 66 of the gripper positioning system 30 are shown in FIG Fig. 2 also shown as arrow arrangements.

The gripper positioning system 30 is designed here as a linear system, wherein the grippers 28a, 28b along respective x-, y- and z-axes both in and against an insertion direction E and in a perpendicular thereto extending traverse plane are movable. Instead of the gripper positioning system 30 could Also, a robot for moving the grippers 28a, 28b may be provided. Each of the grippers 28a, 28b is formed to hold a contact part 32a, 32b via an electric wire 34 attached thereto. In the illustrated embodiment, both contact parts 32a, 32b are connected to each other by a common electrical line 34.

During normal operation of the mounting device initially prefabricated connector housing 14 are first engaged in the corresponding receptacles of a holder 12, for example manually. Subsequently, the holder 12 with the fixed plug housings 14 to the surveying station 10 (FIG. Fig. 1 ). The first camera 19 is then automatically moved by the camera positioning system 20 in front of the reference plate 17. The camera 19 associated image processing system detects the position of the existing in the reference plate 17 recesses 18 and thereby determines the position of the coordinate system 61 of the holder 12 fixed. Subsequently, the first camera 19 is positioned in succession in front of each individual connector housing 14. The image processing system assigned to the first camera 19 in each case determines the position and the rotational position of the plug housing 14. The relative positions of the individual cavities 16 with respect to the associated plug housing 14 are taken from a database. Based on the position of the camera 19 in the trajectory and the determined position of the plug housing 14 in the image, the relative position of the plug housing 14 with respect to the reference plate 17 is determined.

After completion of this surveying operation, the holder 12 with the plug housings 14 to the placement station 24 ( Fig. 2 ). Both grippers 28 a, 28 b engage corresponding contact parts 32 a, 32 b on the common electrical line 34. The grippers 28 a, 28 b are moved by means of the gripper positioning system 30 to the center of the reference plate 17, behind which the camera 26 is located. By means of the image processing system associated with the camera 26, the relative position of the first contact part 32a is related determined on the reference plate 17 and the coordinate system 61 of the holder 12. By means of an electronic control unit, not shown, then the necessary for equipping movement of the gripper 28a is calculated. The electrical line 34 with the contact part 32 a is then moved to the desired connector housing 14 taking into account the determined relative position with respect to the reference plate 17 and the contact part 32 a is inserted into the associated cavity 16 in the insertion direction E. For the second contact part 32b at the other end of the electric wire 34, the process is repeated with the same operations. For process engineering optimization, the working steps for the two contact parts 32a, 32b can be interleaved.

In order to ensure a faultless and efficient operation of the above-described normal operation of the mounting device, an exact alignment of all coordinate systems 61-66 relative to each other is of great importance. In particular, the coordinate systems 61-66 must each be oriented orthogonally or at right angles to each other. In practice, this can only be achieved with considerable effort.

To compensate for misalignments of the individual coordinate systems 61-66, therefore, a method for calibrating the mounting device is performed, which is described below with reference to Fig. 3 and 4 will be described in more detail. First, a marking carrier 38, for example in the form of a paper or film element, is attached to the holder 12. For this purpose, suitable, not shown fastening means may be provided as one or more terminal strips on the holder 12. In the illustrated embodiment, the marker carrier 38 covers substantially the entire front surface of the holder 12, but a recess 42 is provided, which releases the view of the reference plate 17.

The holder 12 with the fastened marking carrier 38 is optionally transported to the loading station 24 and placed in front of the second camera 26. The coordinate system 65 of the second camera 26 aligns with the coordinate system 62 of the reference plate 17. By means of the grippers 28a, 28b, instead of ends of the electrical line 34, respective marking means 40a, 40b are gripped. The marking means 40a, 40b are in Fig. 3 generally shown as arrows. In practice, the marking means 40a, 40b may be designed in particular as pins, needles, laser heads or thermocouples.

The first gripper 28 a is moved with the gripped marking means 40 a to a reference point of the reference plate 17. According to the coordinate system 62 of the reference plate 17, the gripper 28a is first moved in the x-direction, that is, along a horizontal line. At a uniform distance of, for example, 10 mm, the movement is stopped and the gripper 28a is moved in the insertion direction E on the marking support 38 until the tip of the marking means 40a contacts this and thereby sets a marking point 50. Subsequently, a further row of marker points 50 is created with a changed vertical position. Line by line marking points 50 is repeated until the entire working area 52 of holder 12 is covered by a grid-like dot field 54.

After setting all the marking points 50, the holder 12 with the marking carrier 38 attached thereto is moved to the surveying station 10 (FIG. Fig. 1 ) and positioned in front of the first camera 19. The first camera 19 determines the position of the reference plate 17 and thus defines the coordinate system 61 of this particular holder 12. The position data are stored in a memory device of the control unit. They can be used as a reference value for other holders 12. The first camera 19 is then moved by means of the camera positioning system 20 successively to the individual marker points 50 and the positions of the marker points 50 on the marker carrier 38 are respectively determined from the traveling position of the camera positioning system 20 and the position of the marker point 50 in the captured image. The positions of the marking points 50 determined in this way are stored together with the travel coordinates of the gripper positioning system 30 in the memory device, for example as a value table. Subsequently, the calibration process is repeated with the second gripper 28b and the marking means 40b gripped therefrom, wherein in turn the traversing coordinates of the gripper positioning system 30 and the corresponding positions of the marking points 50 are stored together in the storage device.

In a subsequent normal operation of the mounting device, the corresponding travel coordinates of the gripper positioning system 30 can be determined from the positions of the connector housing 14 on the holder 12 using the stored calibration data. Intermediate values can be determined here by suitable mathematical methods, for example by an interpolation method. Possible deviations from an orthogonal and linear movement of the grippers 28a, 28b, which for example lead to a trapezoidal, pincushion-shaped or barrel-shaped distortion of the grid-like point field 54, are detected by the calibration data and can be correspondingly compensated in terms of control technology. If necessary, a check of the calibration of the mounting device can be performed at any time. Both the normal operation and the calibration are coordinated by the above-mentioned control unit of the mounting apparatus.

The invention enables a reliable and cost-effective calibration of the entire placement device.

LIST OF REFERENCE NUMBERS

10

Data collection device

12

holder

14

plug housing

16

cavity

17

reference plate

18

recess

19

first camera

20

Camera positioning system

24

loading station

26

second camera

28a, 28b

grab

30

Gripper positioning system

32a, 32b

contact part

34

electrical line

38

marking carrier

40a, 40b

marker

42

recess

50

marker

52

Workspace

54

points field

61

Coordinate system of the holder

62

Coordinate system of the reference plate

63

Coordinate system of the camera positioning system

64

Coordinate system of the first camera

65

Coordinate system of the second camera

66

Coordinate system of the gripper positioning system

Claims (15)

Method for calibrating a placement device, which is designed to automatically populate a plug housing (14) with a contact part (32a, 32b) attached to an electrical line (34) and a holder (12) for the plug housing (14), a positioning device (30 ) with a movable gripper (28a, 28b) for positioning the contact part (32a, 32b) with respect to the holder (12) and for inserting the contact part (32a, 32b) in an insertion direction (E) into a cavity (16) of the A connector housing (14), an image detecting means (19) for receiving at least a spatially resolved image of at least a part of the holder (12) and a control unit for determining a position of the cavity (16) in the at least one spatially resolved image and determining one for insertion of the contact part (32a, 32b) in the cavity (16) required movement of the gripper (28a, 28b) based on the determined position of the cavity (16),
characterized in that (i) a marking carrier (38) is attached to the holder (12), (ii) gripping a marking means (40a, 40b) with the movable gripper (28a, 28b), (iii) by means of the gripper (28a, 28b) and the marking means (40a, 40b) gripped by the latter, a plurality of marking points (50) are placed on the marking carrier (38) attached to the holder (12), (iv) the positions of the marker points (50) on the marker carrier (38) are determined by means of the image capture device (19) and (V) the determined positions of the marker points (50) are stored in a memory device associated with the control unit. Method according to claim 1,
characterized in that in step (iii) the gripper (28a, 28b) in each case with spaced from the marking carrier (38) marking means (40a, 40b) in a transversely to the insertion direction (E) extending traverse according to predetermined trajectory coordinates of the positioning device (30) is moved to a marking position, wherein
in step (v) in each case the travel coordinates are stored together with the determined position of the associated marker point (50) in the memory device. Method according to claim 2,
characterized in that in step (iii) the gripper (28a, 28b) in each case in the insertion direction (E) on the marking carrier (38) is moved to after the gripper (28a, 28b) has reached the marking position. Method according to one of the preceding claims,
characterized in that in step (iv) the positions of the marking points (50) on the marking carrier (38) are determined relative to a reference mark (17) provided on the holder (12) and detectable by the image detecting device (19). Method according to claim 4,
characterized in that in step (v) also the position of the reference mark (17) is stored in the memory device. Method according to claim 4 or 5,
characterized in that a with the holder (12) connected, preferably made of sheet metal, reference body (17) with at least one, in particular punched or lasered, recess (18) is provided as a reference mark. Method according to one of claims 4 to 6,
characterized in that in step (iii) the gripper (28a, 28b) is first moved to the reference mark (17) and from there to the respective marking position. Method according to one of the preceding claims,
characterized in that in step (iii) the marker points (50) are set line by line or column by column, preferably at a uniform distance from each other. Method according to claim 8,
characterized in that in step (iii) a grid-like point field (54) is formed on the marking carrier (38) by repeated row-wise or column-wise setting of marking points (50), which extends at least over a working area (52) holding the plug housing (14). of the holder (12). Method according to one of the preceding claims,
characterized in that in step (i) a flat labeling medium (38), in particular a paper or film element, is used as marking carrier. Method according to one of the preceding claims,
characterized in that in step (ii) a pin, a needle, a laser head or a thermocouple is used as marking means (40a, 40b). Method according to one of the preceding claims,
characterized in that step (iii) is performed at a placement station (24) of the placement apparatus and step (iv) is performed at a placement station (10) of the placement apparatus separate from the placement station (24). Method according to one of the preceding claims,
characterized in that in step (iv) the image capture device (19) by means of a further positioning device (20) successively moved to the individual marker points (50), wherein the positions of the marker points (50) on the marker carrier (38) respectively from the travel position the further positioning system (20) and the position of the marker point (50) are determined in the captured image. Method according to one of the preceding claims,
characterized in that
the holder (12) is designed to hold a plurality of plug housings (14), wherein in step (iii) the marking points (50) are set such that at least two marking points (50) are associated with each held plug housing (14). Placement device for automatically populating a plug housing (14) with a contact part (32a, 32b) attached to an electrical line (34), which is designed for calibration by means of a method according to one of the preceding claims.

Images