Patent Grant
10396520
This application claims the benefit under 35 U.S.C. § 371 of published PCT Patent Application Number PCT/EP 2015/063349, filed 15 Jun. 2015, claiming priority to European patent application number EP14172587.9 filed on 16 Jun. 2014, the entire contents of which is hereby incorporated by reference herein.
This disclosure generally relates to a method for calibrating a mounting-device, and more particularly relates to a mounting-device which is configured for automatically mounting a connector housing with a contact-part attached to an electrical line.
It is known that the machine-based manufacturing of electrical line harnesses is often carried out by the use of robots or similar positioning devices that are equipped with grippers as end effectors. Usually, such a gripper holds a contact-part either directly or at the electrical line, moves it to the desired cavity and inserts it therein. The term “connector housing” is basically meant to be also a socket housing, a clamping bar or the like. To ensure a reliable and efficient mounting process, an accurate knowledge of the positions of the respective components of the system is required.
For cost reasons, neither the connector housings nor the contact-parts of conventional electrical lines can be manufactured with strict tolerance allowances. Accordingly, inaccuracies regarding the positioning arise repeatedly when using common mounting-devices, whereby reliable and efficient operation is made difficult. An observation of the holder by a camera can help here only partially. In particular, position deviations of the gripper that arise only in the course of the positioning and insertion movement may not be considered by the camera in general.
DE 10 2007 027 877 A1 discloses a method for calibrating a setting head for contact elements, wherein a calibration plate is laterally movably mounted on a holder and subsequently a contact pin is inserted into a passage of the calibration plate. After the insertion process, the calibration plate is locked and the position of the passage is determined by the camera.
Described herein is a method for calibrating a mounting-device for automatically mounting a connector housing with a contact-part attached to an electrical line. It is an object of the invention, even when using positioning devices, connector housings, holders and/or contact-parts with tolerances, to allow for exact, error-free and fast mounting of a connector housing with a contact-part attached to an electrical line.
In accordance with one embodiment, a method for calibrating a mounting-device is provided. The method comprises the steps of :
Since the marking points are set with the same movable gripper, with which the contact-parts are positioned and inserted during normal operation of the mounting-device, each marking point indicates exactly that position which is approached during the mounting process with respective control of the positioning system. Deviations of the displacement movement from a predetermined course are irrelevant herein. Regardless of the extent to which such deviations occur and how they arise, in any case such a marking point indicates the exact insertion position which results from the respective control of the positioning device.
During normal operation of the mounting-device, the stored positions of the marking points may be retrieved and taken into consideration in the calculation of the displacement movement of the gripper required for mounting. With the calibration method according to the invention, it is thus possible, within the machine control, to completely compensate for all mechanical tolerances and deviations of the mounting-device and of the provided connector housings and contact-parts. A particular benefit of the calibration method according to the invention is that it may be performed with the already provided camera.
Preferably, in step (iii), the gripper is moved with marking-device spaced from the marking carrier in a displacement plane transverse to the insertion direction in accordance with predetermined displacement coordinates of the positioning device to a marking position, respectively, wherein in step (v) the displacement coordinates together with the determined position of the associated marking point are stored in the storage device, respectively. Thus, the marking points are each assigned to those displacement coordinates on which their generation is based. In this configuration, not only the positions of the marking points are stored in the storage device, but also the respective causal control parameters. After completion of the calibration method, during normal operation of the mounting-device, it can be proceeded such that the suitable displacement coordinates or control parameters are located with predetermined insertion position.
Preferably, in step (iii), the gripper is moved respectively in the insertion direction towards the marking carrier, after the gripper has reached the marking position. In this way, each marking point is exactly set at the position at which a contact-part would be inserted, if it would be held by the gripper instead of the marking-device. Thus, the positions of the marking points are directly and immediately associated with insertion positions of contact-parts.
In another embodiment, the method provides that in step (iv) the positions of the marking points on the marking carrier are determined in relation to a reference-marking provided on the holder, identifiable by the camera. By using such a reference-marking, the positions of the marking points in relation to the holder can be determined particularly exact—even if the camera has various positions when determining the positions of the marking points on the marking carrier in step (iv).
In step (v), the position of the reference-marking can also be stored in the storage device. The stored position of the reference-marking can be used as reference value for other holders.
In yet another embodiment, the method provides that a reference-body, connected to the holder and preferably made of sheet metal, having at least one in particular punched or lasered recess, is provided as reference-marking. The detection of a sharply edged recess in a camera image is possible with relatively high accuracy with suitable illumination. A reference-body in the form of a lasered sheet metal is relatively inexpensive to produce. The edges of the recess can be detected from both sides of the reference-body, if necessary, regardless of whether the camera is in front of or behind the holder. To ensure a particularly reliable detection of the reference-marking, an arrangement of several recesses on the reference-body can be provided.
In yet another embodiment, the method provides that, in step (iii), the gripper is initially moved to the reference-marking and from there to the respective marking position. The positioning of the marking-device in relation to the reference-marking may be verified by the camera. In this way, the marking points are set in relation to the coordinate system of the holder.
In step (iii), the marking points can be set in rows or columns, preferably in a uniform distance from each other. In this way, lines with spaced marking points can be created on the marking carrier, which can be used similar to a scale for determining the position.
In particular, in step (iii), a grid-like array of points can be created on the marking carrier by repeatedly setting of marking points row-wise or column-wise, extending at least over a operation area of the holder holding the connector housing. By such a grid-like array of points, an entire area of the holder and, if necessary, even the entire holder can be included in the calibration.
Preferably, in step (i), a flat labeling medium is used as marking carrier, in particular a paper or foil element. Such a flat labeling medium can be easily attached to a front of the holder facing the gripper. To this end, suitable attachment method may be provided at the holder such as, for example, one or more clamping bars.
In step (ii), in particular a pin, a needle, a laser head or a thermal element can be used as marking-device. The use of a pin or needle is particularly cost-efficient. In contrast, the use of a laser head or thermal element allows for setting of particularly fine and/or structured marking points.
In yet another embodiment, the method provides that step (iii) is carried out at a mounting 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 measuring station and a separate mounting station at a mounting-device is procedurally advantageous. In particular, in such an embodiment, a contact-part can be inserted during normal operation, while at the measuring station a further holder with connector housing is already measured. Advantageously, both stations can be used for calibration of the system.
In yet another embodiment, the method provides that, in step (iv), the camera is successively moved to the individual marking points by way of a further positioning device, wherein the positions of the marking points on the marking carrier are each determined from the displacement position of the further positioning system and the position of the marking point in be the captured image. By individually approaching the marking points, the determination of a position of a marking point in the image can be made with very high resolution. For cost-efficiency, it is also possible, due to the individually approaching of the marking points, to use the camera with a comparatively low resolution.
It may be provided that the holder is configured for holding a plurality of connector housings, wherein in step (iii) the marking points are set such that at least two, preferably at least five, marking points are associated with each held connector housing. This ensures a sufficiently accurate consideration of any positional deviations.
The invention also relates to a mounting-device for automatically mounting a connector housing with a contact-part attached to an electrical line, which comprises a holder for the connector housing, a positioning device with a movable gripper for positioning the contact-part in relation to the holder and for inserting the contact-part in a direction of insertion into a cavity of the connector housing, the camera for capturing at least one spatially resolved image of at least 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 movement of the gripper required for inserting the contact-part into the cavity using the determined position of the cavity.
According to the invention a control unit of the mounting-device is configured to carry out a calibration method as described above. Such a calibration function allows for reliable compensation of all tolerances and deviations of the entire system.
Further features and advantages will appear more clearly on a reading of the following detailed description of the preferred embodiment, which is given by way of non-limiting example only and with reference to the accompanying drawings.
The present invention will now be described, by way of example with reference to the accompanying drawings, in which:
The measuring station 10 shown in
A first-camera 19 with associated image processing system (not shown) is provided to capture spatially resolved images of a part of the holder 12 including the connector-housings 14 fixed thereto. The first-camera 19 is attached to a camera-positioning-system 20 such that it may be positionally moved in front of the individual connector-housings 14. In the embodiment illustrated, the camera-positioning-system 20 is configured as a two-axis linear system. For reasons of clarity, the holder 12 with the fixed connector-housings 14 and the camera-positioning-system 20 are depicted in front view, while the first-camera 19 is shown in plan-view. The holder 12, the reference-body 17, the camera-positioning-system 20 and the first-camera 19 have assigned respective coordinate systems, which are shown as arrow arrangements in
The mounting-station 24 shown in
The gripper-positioning-system 30 is here configured as a linear system, wherein the grippers 28a and 28b are moveable along respective x-, y- and z-axes, both in and opposite to an insertion-direction E and also in a displacement plane extending at a right angle thereto. A robot could also be provided for moving the grippers 28a and 28b instead of the gripper-positioning-system 30. Each of the grippers 28a and 28b is configured for holding a first-contact-part 32a and a second-contact-part 32b via an electrical line 34 attached thereto. In the illustrated embodiment, both contact-parts 32a and 32b are interconnected by a common electrical line 34.
During normal operation of the mounting-device, respective prefabricated connector-housings 14 are initially locked into the associated receptacles of a holder 12, for example manually. Subsequently, the holder 12 with the fixed connector-housings 14 is transported to the measuring-station 10 (
Upon completion of this measurement process, the holder 12 with the connector-housings 14 is transported to the mounting-station 24 (
To ensure an error-free and efficient process of the above described normal operation of the mounting-device, an exact alignment of all coordinate systems 61-66 in relation to each other is very important. In particular, the coordinate systems 61-66 each need to be aligned orthogonally and at right angles to each other. In practice, this is achievable only with substantial effort.
For compensation of erroneous alignments of the individual coordinate systems 61-66, a method for calibrating the mounting-device is carried out, which will be described below in more detail with reference to
The holder 12 with the attached marking-carrier 38 is optionally transported to the mounting-station 24 and placed in front of the second-camera 26. The camera-coordinate-system 65 of the second-camera 26 is aligned with the reference-body-coordinate-system 62 of the reference-body 17. Respective marking-device 40a and 40b instead of ends of the electrical line 34 are gripped by the grippers 28a and 28b. The marking-device 40a and 40b are generally shown as arrows in
The first-gripper 28a with the gripped marking-device 40a is moved to a reference point of the reference-body 17. According to the reference-body-coordinate-system 62 of the reference-body 17, the gripper 28a is first moved in the x direction, i.e. along a horizontal line. At a uniform distance of 10 mm, for example, the movement is stopped and the first-gripper 28a is moved in the insertion-direction E towards the marking-carrier 38 until the tip of the marking-device 40a contacts therewith and thus sets a marking-point 50. Subsequently, another row of marking-points 50 is created with altered vertical position. The row by row setting of marking-points 50 is repeated until the entire operation area 52 of the holder 12 is covered by a grid-like array of points 54.
After setting of all marking-points 50, the holder 12 with the attached marking-carrier 38 is moved to the measuring-station 10 (
At a subsequent normal operation of the mounting-device, the respective displacement coordinates of the gripper-positioning-system 30 can be determined from the positions of the connector-housings 14 at the holder 12 using the stored calibration data. Here, intermediate values can be determined by suitable mathematical methods, for example by an interpolation method. Any deviations from an orthogonal and linear movement of the grippers 28a and 28b, which for example lead to a trapezoidal, cushion-like or barrel-like distortion of the grid-like array of points 54, are determined by the calibration data and can be compensated accordingly in terms of control. If necessary, an examination of the calibration of the mounting-device may be carried out at any time. Both the normal operation and the calibration are coordinated by the above described control unit of the mounting-device.
Accordingly, a method for calibrating a mounting-device is provided. The method enables a reliable and cost-effective calibration of the entire mounting-device.
While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.
| Number | Date | Country | Kind |
|---|---|---|---|
| 14172587 | Jun 2014 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/063349 | 6/15/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/193247 | 12/23/2015 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5537204 | Woodhouse | Jul 1996 | A |
| 5806753 | Bielick | Sep 1998 | A |
| 6999835 | Kodama | Feb 2006 | B2 |
| 20090228144 | Okazaki et al. | Sep 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 102738683 | Jul 2008 | CN |
| 103682949 | Oct 2012 | CN |
| 102007027877 | Dec 2008 | DE |
| Number | Date | Country | |
|---|---|---|---|
| 20170117678 A1 | Apr 2017 | US |
