Calibrating A System With A Conveying Means And At Least One Robot

Abstract

A method for calibrating a system with a conveying apparatus and at least a first robot includes determining the positions of at least three measuring points of a first component transported by the conveying apparatus in a first transport position using the first robot. The method further includes determining the position of at least one of the measuring points in a second transport position using the first robot, or determining the positions of at least two of the measuring points of the component in a third transport position and the position of at least one other measuring point in the third transport position or at least one of these measuring points in a fourth transport position using at least one second robot.

Claims

1. Method for calibrating a system with a conveying means (30) and a first robot (10), said method comprising the step of: determining the positions of at least, in particular, exactly, three measuring points (P.sub.1, 1, P.sub.1, 2, P.sub.1, 3) of a first measuring point system, in particular, component, (W1), transported by the conveying means, in a transport position (.sub.a) by means of the first robot; and at least one of the steps of: determining the position of at least, in particular, exactly, one of these measuring points (P.sub.1, 1) in another transport position (.sub.b) by means of the first robot; and/or determining the positions of at least, in particular, exactly, two measuring points (P.sub.1, 1, P.sub.1, 2/3) of the first measuring point system, in particular, component, in a transport position (.sub.c; .sub.c) and the position of at least, in particular, exactly, one further measuring point (P.sub.1, 3/2) in this transport position (.sub.c) or at least, in particular, exactly, one of these measuring points (P.sub.1, 1) in another transport position (.sub.d) by means of at least one second robot (20) of the system.

2-12. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the present invention.

[0090] FIG. 1 depicts an exemplary conveying system for calibration by a method in accordance with the present disclosure.

[0091] FIG. 2 depicts the conveying system of FIG. 1 in a second configuration wherein calibration component is in a different position.

[0092] FIG. 3 depicts the conveying system of FIG. 2 wherein the calibration component is further moved.

[0093] FIG. 4 depicts the conveying system of FIG. 3 wherein the calibration plate is further moved and a second calibration plate is introduced.

DETAILED DESCRIPTION

[0094] FIG. 1 shows a system with a linear conveying means in the form of a conveyor belt 30, a first robot 10 and a second robot 20 for handling and/or machining first and second components, which differ from each other and/or in their orientation and/or position perpendicular to the direction of transport of the conveyor belt (vertically upwards in FIG. 1).

[0095] The invention is described below by way of example with reference to the two robots and types of component; it goes without saying that analogous to the one second robot, additional (second) robots and/or, analogous to the one second component, additional (second) components may also be present; the and/or their orientation and/or position perpendicular to the direction of transport of the conveyor belt differ/differs from that or those of the first and a second component(s), where in this case the features described herein can be realized in the same way even for these additional robots and/or components.

[0096] In a step illustrated in FIG. 1, a plate-like calibration component W1 is placed on the conveyor belt in such a way that its orientation and position transverse to the direction of transport of the conveying means corresponds to a first component.

[0097] Calibration component W1 has three measuring points P.sub.1, 1, P.sub.1, 2, and P.sub.1, 3, which are geometrically defined in such a way that they can be probed by the robots 10, 20 with precision. As an alternative, one of the first components can also be used directly. As an alternative, the measuring points can also be arranged or formed on the conveyor belt itself; or a measuring point system, formed integrally with the conveyor belt, can be used.

[0098] A camera of a transport position determining means 40 is used for capturing, as soon as the calibration plate W1 passes a synchronization position, indicated in FIG. 1 by a horizontal dashed line. As indicated by vertical arrows upwards in FIGS. 2 to 4, a transport position of the calibration plate W1 relative to this synchronization position is determined on the basis of a movement of the conveying means, with said movement being detected by a rotary encoder of the transport position determining means 40, in particular, on the basis of an angle of rotation y of the rotary encoder.

[0099] In this case, in the position shown in FIG. 1, the camera of the transport position determining means 40 can be calibrated by means of the calibration component W1. In particular, for this purpose the calibration component can be arranged by means of the conveying means 30 in the field of view of the camera; and intrinsic and/or extrinsic camera parameters can be determined on the basis of the camera image.

[0100] In a step shown in FIG. 2, the calibration plate W1 is transported by the conveyor belt 30 into a transport position .sub.a, in which the positions p.sub.1, 1, (.sub.a), p.sub.1, 2, (.sub.a), p.sub.1, 3, (.sub.a) of the three measuring points P.sub.1, 1, P.sub.1, 2 and P.sub.1, 3 are determined by means of the first robot 10 in its robot-fixed coordinate system R1, indicated by x.sub.R1, y.sub.R1, in that said robot probes the measuring points. As an alternative, measuring points could also be detected visually; or geometrically defined straight lines or planes could be traversed.

[0101] On the basis of these positions, a controller 11 of the first robot 10 defines a component-fixed coordinate system W11(.sub.a) of the calibration plate W1 and the first robot, with the origin of said coordinate system lying at the point P.sub.1, 1; with the X axis of said coordinate system passing through the point P.sub.1, 2; with the Z axis of said coordinate system being perpendicular to the plane of transport, defined by the points P.sub.1, 1, 1, 2 and P.sub.1, 3; and with said coordinate system being indicated by x.sub.W11, y.sub.W11.

[0102] In a step shown in FIG. 3, the calibration plate W1 is transported by the conveyor belt 30 into another transport position .sub.b, in which the position p.sub.1, 1 (.sub.b) of the measuring point P.sub.1, 1 is determined by means of the first robot 10 in its robot-fixed coordinate system R1.

[0103] On the basis of the positions p.sub.1, 1 (.sub.a), p.sub.1, 1 (.sub.b) and p.sub.1, 2 (.sub.a) or p.sub.1, 3 (.sub.a) the controller 11 defines a conveying means base-fixed coordinate system C1 of the first robot, with the X axis of said coordinate system passing through the positions p.sub.1, 1 (.sub.a), p.sub.1, 1 (.sub.b) and, thus, aligned with the direction of transport; with the Z axis of said coordinate system being perpendicular to the transport plane, defined by three of the positions p.sub.1, 1 (.sub.a), p.sub.1, 1 (.sub.b), p.sub.1, 2 (.sub.a) and p.sub.1, 3 (.sub.a); with the origin of said coordinate system lying, for example, in the positions p.sub.1, 1 (.sub.a) or p.sub.1, 1 (.sub.b); and said coordinate being indicated by means of x.sub.C1, y.sub.C1.

[0104] In addition, a rotary encoder transmission ratio of the encoder of the transport position determining means 40 is calibrated on the basis of the position p.sub.1, 1 (.sub.a), determined by means of the first robot 10, of the measuring point P.sub.1, 1 in the one transport position and on the basis of the position p.sub.1, 1 (.sub.b), determined by means of the first robot 10, of the same measuring point P.sub.1, 1 in the other transport position: by determining the positions of the same measuring point in the one and in the other transport position it is possible to determine, in particular, a (transport) distance, traveled by the measuring point P.sub.1, 1 and, thus, also by the conveying means 30. By comparing this (transport) distance with the angle of rotation , which the rotary encoder of the transport position determining means 40 has detected between the one and the other transport position, it is possible to determine a rotary encoder transmission ratio between the (transport) distance of the conveying means 30 and the angle of rotation of the rotary encoder of the transport position determining means 40: [|p.sub.1, 1 (.sub.b)p.sub.1, 1 (.sub.a)|/]

[0105] Subsequently, the component-fixed coordinate system W11 of the calibration plate W1 and the first robot is rotated by .sub.a, i.e., displaced into the synchronization position (W11=W11 (=0)), in the direction opposite to the X axis of the coordinate system C1, so that later in operation the origin of the component-fixed coordinate system is in the synchronous position after the synchronization switch has been triggered, and determines the transformations T.sub.R1, C1 between the conveying means base-fixed coordinate system C1 and the robot-fixed coordinate system R1 as well as T.sub.C1, W11 between the component-fixed coordinate system W11 and the conveying means base-fixed coordinate system C1.

[0106] It can be seen that advantageously both coordinate systems C1, W11 or transformations T.sub.R1, C1, T.sub.C1, W11 are determined advantageously on the basis of only four determined positions p.sub.1, 1 (.sub.a), p.sub.1, 1 (.sub.b), p.sub.1, 2 (.sub.a) and p.sub.1, 3 (.sub.a).

[0107] In a step illustrated in FIG. 4, the calibration plate W1 is transported by the conveyor belt 30 into a transport position .sub.c, in which the positions p.sub.1, 1 (.sub.c) and p.sub.1, 2 (.sub.c) or p.sub.1, 3 (.sub.c) of the measuring points P.sub.1, 1 and P.sub.1, 2 or P.sub.1, 3 are determined by means of the second robot 20 in its robot-fixed coordinate system R2, indicated by x.sub.R2, y.sub.R2. Subsequently the calibration plate W1 is transported, analogous to the sequence of figures FIG. 2.fwdarw.FIG. 3, by the conveyor belt 30 into another transport position .sub.d, in which the position p.sub.1, 1 (.sub.d) of the measuring point PR, 1 is determined by means of the second robot 20 in its robot-fixed coordinate system R2.

[0108] On the basis of the positions p.sub.1, 1 (.sub.c), p.sub.1, 1 (.sub.d) and p.sub.1, 2 (.sub.c) or p.sub.1, 3 (.sub.c) a controller 21 of the second robot 20 defines a conveying means base-fixed coordinate system C2 of the second robot, with the X axis of said coordinate system passing through the positions p.sub.1, 1 (.sub.c), p.sub.1, 1 (.sub.d) and, as a result, is aligned with the direction of transport; with the Z axis of said coordinate system being perpendicular to the transport plane, defined by three of the positions p.sub.1, 1 (.sub.c), p.sub.1, 1 (.sub.d), p.sub.1, 2 (.sub.c) and p.sub.1, 3 (.sub.c); and with the origin of said coordinate system being, for example, in the position p.sub.1, 1 (.sub.c) or p.sub.1, 1 (.sub.d); and said coordinate system is indicated by x.sub.C2, y.sub.C2.

[0109] A transformation T.sub.C2, W12 between this conveying means base-fixed coordinate system C2 of the second robot 20 and a component-fixed coordinate system W12 of the calibration plate W1 and the second robot 20 is determined by the controller 21 on the basis of the transformation T.sub.C1, W11 between the conveying means base-fixed coordinate system C1 of the first robot 10 and the component-fixed coordinate system W11 of the calibration plate W1 and the first robot 10. For this purpose the controller 11 transmits the (parameters of) T.sub.C1, W11 to the controller 21, which is connected or communicates with said controller by data technology.

[0110] Since the two coordinate systems C1, C2 of the first and second robot are displaced relative to each other only along their aligned X axis, the rotation into the component-fixed coordinate system or the transformation T.sub.C1, W11 can be applied directly or unchanged. The component-fixed coordinate system W12 of the calibration plate W1 and the second robot 20 is also displaced relative to the X axis of the coordinate system C2 into the synchronization position; this displacement can also be determined, in the same manner as the displacement of the coordinate systems C1, C2, directly from the transport positions.

[0111] If in a modification the origin of the conveying means base-fixed coordinate system C2 of the second robot 20 and the origin of the conveying means base-fixed coordinate system C1 of the first robot 10 coincide, since, for example, the coordinate system C2 has been moved correspondingly (.sub.a/b.sub.c/d) relative to the X axis of the coordinate system C2 into the origin of the coordinate system C1, then the transformation T.sub.C1, W12 can be applied even completely directly or unchanged (T.sub.C2, W12=T.sub.C1, W11).

[0112] It can be seen that both coordinate systems C2, W12 or transformations T.sub.R2, C2, T.sub.C2, W12 are determined advantageously on the basis of only three determined positions p.sub.1, 1 (.sub.c), p.sub.1, 1 (.sub.d) and p.sub.1, 2 (.sub.c) or p.sub.1, 3 (.sub.c) and the transmitted transformation T.sub.C1, W11 between the conveying means base-fixed coordinate system C1 of the first robot 10 and the component-fixed coordinate system W11 of the calibration plate W1 and the first robot 10.

[0113] FIG. 4 also shows the calibration of a second calibration plate W2 by the first robot 10, with the orientation and position of said calibration plate transverse to the direction of transport of the conveying means corresponding to a second component.

[0114] In an analogous manner, explained above with reference to W1 and FIGS. 2, 3, it is also possible to determine for this second calibration plate W2 (or the second components) by determining the positions p.sub.2, 1 (.sub.a), p.sub.2, 2 (.sub.a) and p.sub.2, 3 (.sub.a) of three measuring points P.sub.2, 1, P.sub.2, 2, and P.sub.2, 3 by means of the first robot 10 in its coordinate system R1, a component-fixed coordinate system W21 (.sub.a) of the calibration plate W2 and the first robot, and from this, after the displacement of said coordinate system into the synchronization position, the transformation T.sub.C1, W21 between this component-fixed coordinate system W21=W21 (=0) and the conveying means base-fixed coordinate system C1.

[0115] In an analogous manner explained above with reference to W11, W12 and FIG. 4, it is also possible to determine for this second calibration plate (or the second components) for the second robot in each case a transformation T.sub.C2, W22 between a component-fixed coordinate system W22, in particular, displaced into the synchronization position, of the second calibration plate W2 and the conveying means base-fixed coordinate system C2 of the second robot on the basis of this transformation T.sub.C1, W21 between the component-fixed coordinate system W11 and the conveying means base-fixed coordinate system C1 of the first robot.

[0116] Similarly, the controller 11 can determine then the transformation T.sub.W1, W21 between the two component-fixed coordinate systems W11, W21 and the first robot, for example, according to T.sub.W11, W21=T.sub.C1, W21 (T.sub.C1, W11).sup.1. This transformation can be transmitted by the controller 11 to the controller 21, which can easily determined therefrom and the already determined transformation T.sub.C2, W12 the transformation T.sub.C2, W22, for example, according to T.sub.C2, W22=T.sub.W11, W21 T.sub.C2, W12.

[0117] It can be seen that advantageously a new component, in the example explained above, has to calibrate, as an example, the second component or its corresponding calibration plate W2, only for or by the first robot 10; and the transformations between the conveying means base-fixed and the component-fixed coordinate system of the other robot, in the example explained above, as an example, the second robot 20, are determined on the basis of the transformations between the two component-fixed coordinate systems W11, W21 and the first robot. Instead of this transformation T.sub.W11, W21, it is also possible for the transformation T.sub.C1, W21 to be transmitted to the controller 21, which can determine from this in turn the transformation T.sub.C2, W22 in the manner explained above.

[0118] If the second robot 20 is exchanged with a third robot, then the positions p.sub.1, 1 (.sub.a), p.sub.1, 2 (.sub.a) and p.sub.1, 3 (.sub.a) are determined, in an analogous manner explained above with reference to FIGS. 2, 4, by means of the first robot; and the positions p.sub.1, 1 (.sub.c), p.sub.1, 2 (.sub.c) and p.sub.1, 3 (.sub.c) of the measuring points of a calibration plate W1 or a component itself are determined by means of the new third robot. This calibration plate W1 serves only as a reference body for calibrating the exchanged third robot and, therefore, does not have to correspond to any component.

[0119] The distance between these two transport positions .sub.a, .sub.c corresponds to the distance between the two transport positions .sub.a, .sub.c, at which the positions p.sub.1, 1 (.sub.a), p.sub.1, 2 (.sub.a) and p.sub.1, 3 (.sub.a) were determined by means of the first robot, and the positions p.sub.1, 1 (.sub.c) and p.sub.1, 2 (.sub.c) or p.sub.1, 3 (.sub.c) were determined (.sub.c.sub.a=.sub.c.sub.a) by means of the exchanged second robot, so that the displacement of the two conveying means base-fixed coordinate systems of the original and of the exchanged robot to the conveying means base-fixed coordinate system of the first robot remains the same. In one embodiment the original transport positions were stored for this purpose.

[0120] The controller 11 determines on the basis of the positions p.sub.1, 1 (.sub.a), p.sub.1, 2 (.sub.a) and p.sub.1, 3 (.sub.a), in the manner explained above, a component-fixed coordinate system W11, on the basis of which a transformation T.sub.C1, W11 between this component-fixed coordinate system W11 and the conveying means base-fixed coordinate system C1 of the first robot, and transmits this transformation T.sub.C1, W11 (or its parameters) to the controller of the new, third robot. Said controller determines, on the basis of the positions p.sub.1, 1 (.sub.c), p.sub.1, 2 (.sub.c) and p.sub.1, 3 (.sub.c), in the manner explained above, a component-fixed coordinate system W12; from this the transformation T.sub.R2, W12 between the component-fixed coordinate system W12 and the coordinate system R2 of the new robot, and therefrom the transformation T.sub.R2, C2 between a robot-fixed coordinate system R2 and the corresponding conveying means base-fixed coordinate system C2 of the new robot, for example, according to T.sub.R2, C2=(T.sub.C1, W11).sup.1 T.sub.R2, W12, provided the coordinate systems C1, C2 match.

[0121] It can be seen that advantageously when exchanging a robot only its conveying means base-fixed coordinate system is recalibrated in a simple manner.

[0122] If the camera 40 is exchanged, then this corresponds to a modification of the transport position determining means, since another synchronization position is defined by the exchanged camera.

[0123] Therefore, in such a case, in an analogous manner explained above with reference to FIGS. 2, 4, the positions p.sub.1, 1 (.sub.a), p.sub.1, 2 (.sub.a) and p.sub.1, 3 (.sub.a) as well as p.sub.2, 1 (.sub.a), p.sub.2, 2 (.sub.a) and p.sub.2, 3 (.sub.a) of the calibration plates W1, W2 or a first or second component are determined again by means of the first robot.

[0124] In an analogous manner explained above with reference to W11, W12 and FIG. 4, it is also possible to determine for the second robot respectively a transformation T.sub.C2, W12, T.sub.C2, W22 between a component-fixed coordinate system of the calibration plate W1 or W2 and the conveying means base-fixed coordinate system C2 of the second robot on the basis of the new synchronization position.

[0125] For this purpose, in particular, the controller 11 can determine then, in an analogous manner explained above, for each calibration plate respectively the transformation T.sub.W11, W11 or T.sub.W21, W21 between the two component-fixed coordinate systems and the first robot for the old and new synchronization position: T.sub.W11, W11=T.sub.C1, W11 (T.sub.C1, W11).sup.1 or T.sub.W12, W12=T.sub.C1, W12 (T.sub.C1, W12).sup.1. This transformation can be transmitted by the controller 11 to the controller 21, which can determine therefrom and the already determined transformation T.sub.C2, W12 or T.sub.C2, W22 in a simple way the transformations T.sub.C2, W12, T.sub.C2, W22: T.sub.C2, W12=T.sub.W11, W11 T.sub.C2, W12 or T.sub.C2, W22=T.sub.W21, W21 T.sub.C2, W22. Similarly the controller 11 can also transmit the transformations T.sub.C1, W11, T.sub.C1, W21 to the controller 21.

[0126] It can be seen that advantageously when modifying the transport position determining means only the component-fixed coordinate systems of the first robot are recalibrated.

[0127] Although exemplary embodiments have been explained in the foregoing description, it should be pointed out that a variety of modifications are possible. It should also be noted that the exemplary embodiments are merely examples that are not intended to limit the scope of protection, the applications and the configuration in any way. Instead, the preceding description gives the skilled person a guide for the implementation of at least one exemplary embodiment, where in this case various changes, in particular, with regard to the function and arrangement of the described components, can be made without departing from the scope of protection, which will become apparent from the claims and combinations of features equivalent thereto.

[0128] While the present invention has been illustrated by a description of various embodiments, and while these embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features shown and described herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit and scope of the general inventive concept.

LIST OF REFERENCE NUMERALS AND SYMBOLS

[0129]

TABLE-US-00001 10 first robot 11 robot controller of the first robot 20 second robot 21 robot controller of the second robot 30 conveyor belt 40 transport position determining means (camera, encoder) P.sub.i, j measuring point j of the calibration body Wi Wi calibration plate (component) .sub.(a, a , a, b, c, c, d) transport position(s) T.sub.Ri, Ci transformation between robot-fixed and conveying means base-fixed coordinate system of the i. robot T.sub.Ci, Wji transformation between conveying means base- fixed and component-fixed coordinate system of the component j and the i. robot