1. Field of the Invention
The invention relates to a picking system for the automated picking of articles, comprising a detection station for detecting the position of an article to be picked on a supplying conveyor unit and comprising an articulated arm gripper for picking up the article from a storage loading implement from the supplying conveyor unit and for depositing the article in an order loading implement on a discharge unit, wherein the articulated arm gripper can be positioned by a kinematic unit of the picking system within an operational range of the kinematic unit and wherein the articulated arm gripper comprises an essentially upright longitudinal arm and an articulated arm which can be bent about an angle of articulation and on which a gripping device for gripping the article is provided.
2. Description of the Related Art
Document EP 1 160 166 B1 discloses a sorting system wherein articles are supplied in the form of food slices on a first conveyor belt to two robots by means of which the food slices are sorted into a package on a second conveyor belt. The robots comprise a kinematic unit which, based on a so-called delta kinematics, is formed with three delta arms. On the kinematic unit, a gripper is mounted by means of which one food slice at a time is picked up from the first conveyor belt by a vacuum gripper and is deposited onto an oblique surface into a package on the second conveyor belt. For this purpose, the gripper comprises an arm which is attached to a longitudinal arm and is bent about a particular angle which, at one point, has been adjusted.
An optical detection station comprises a detection cone which is directed at the first conveyor belt and detects the position of the food slices on the conveyor belt. Said position information is transmitted to a control device of the sorting system, which actuates the two robots. For picking up a food slice, the kinematic system positions the gripper directly above the food slice on the first conveyor belt and the vacuum gripper applies suction to the food slice. For depositing the food slice, the control device positions the gripper with the food slice that has been picked up over a free position of the package. During the positioning of the gripper from the first conveyor belt to the second conveyor belt, an angle of rotation of the gripper about the longitudinal arm of the articulated arm gripper is thereby adjusted from a first angle of rotation when the food slice is being picked up, which angle is always the same, into a second angle of rotation for releasing the food slice, which angle is always the same. Subsequently, the vacuum gripper releases the food slice into the package. During the construction of the picking system, the arm's angle of articulation was once adjusted to the location of the supplying conveyor unit and the discharge unit.
The known sorting system has turned out to have the drawback that, with the gripper, articles can only be picked up from the flat first conveyor belt and deposited in the flat package on the second conveyor belt. The supply of the food slices on the first conveyor belt does not happen from storage loading implements, but said slices are supplied to the robots in an isolated manner. The situation is different with articles to be picked from an order picking warehouse, wherein, in most cases, the articles are stored in particular storage loading implements. This leads to different requirements for the kinematic unit and in particular for the articulated arm gripper which are not fulfilled by the known gripper.
The present invention is based on the problem of providing an automated picking system with an articulated arm gripper, wherein the previously mentioned disadvantages are avoided. According to the invention, this problem is solved in that the articulated arm gripper is designed for picking up the article to be picked from storage loading implements which are transported on the supplying conveyor, wherein the longitudinal arm of the articulated arm gripper is at least twice and in particular at least five times as long as the articulated arm of the articulated arm gripper, and that the detection station is designed for detecting the three-dimensional position of the article in the storage loading implement and that the angle of articulation of the articulated arm and an angle of rotation of the articulated arm gripper are freely adjustable about the longitudinal arm, depending on the detected position for gripping the article.
In this way, the advantage is achieved that the articulated arm can also grip articles from a storage loading implement which optionally are positioned in a strongly inclined and/or hard-to-reach manner. Articles in a storage loading implement are strongly inclined particularly if a planar article surface is inclined toward the horizontal and optionally collides with the wall of the loading implement. Articles in a storage loading implement are hard to reach particularly if they are located in one of the corners of the storage loading implement or if they are located, partly covered, under other articles in the form of a bulk material of optionally different articles.
Via the three-dimensional detection of the position of the article to be picked in the storage loading implement and via the free adjustability of the angle of articulation and the angle of rotation of the articulated arm in combination with the relatively long longitudinal arm and the short articulated arm, the articulated arm gripper can be adjusted and positioned in precisely such a way that also articles to be picked which are difficult to access in the storage loading implement can be picked up with maximum gripping force and precision.
When the gripping device is designed as a vacuum gripper, it has turned out to be beneficial to apply suction to the article with the vacuum gripper and to prop it up against at least two and particularly advantageously against at least three supports. In this way, it is avoided that the article swings or even falls from the vacuum gripper when the kinematic unit is accelerated during gripping. It is particularly advantageous to adjust the support points depending on the article size or the article weight in order to obtain a bearing surface within the support points which is as large as possible. For this purpose, the distance of the support points of the vacuum gripper can be adjusted electromechanically, or the entire gripper can be exchanged for a gripper with different support points at a gripper changing station as described hereinbelow.
Furthermore, it has turned out to be advantageous to place the articulated arm of the articulated arm gripper in a vertical position, i.e., in the direction of the longitudinal arm, either by gravity or, for example, by means of a retaining spring, immediately after the article has been gripped. In this way, the gripping device is able to secure the article which has been picked up considerably more firmly.
Depending on the spatial position which the article to be picked assumes in the storage loading implement and depending on from which position of the storage loading implement the article is to be picked up by the articulated arm gripper, different approach strategies and actuation runs, respectively, of the kinematic unit are advantageous for positioning the articulated arm gripper. If the article to be picked is hard to reach and/or difficult to access since the articulated arm gripper only has a relatively small space for gripping the article, it has turned out to be advantageous that the articulated arm gripper with the articulated arm placed vertically downward is brought by the kinematic unit into the position for picking up the article and that, only then, the articulated arm is adjusted to the angle of articulation as predetermined by the control device. On the other hand, an article which is readily accessible in the storage loading implement to be picked up can be picked up faster if the articulated arm of the articulated arm gripper is adjusted to the predetermined angle of articulation and angle of rotation already during the positioning operation by the kinematic unit.
Furthermore, it has turned out to be advantageous if articles to be picked for an order are, for the moment, deposited on an intermediate buffer platform by one or several storage loading implements, which are delivered on the supplying conveyor, and are poured jointly into the second order loading implement allocated to the order. In doing so, it is particularly advantageous to pick shock-sensitive articles to be picked or articles which, due to their size or their weight, are the first or, respectively, last ones to be placed in the order loading implement directly into the order loading implement by means of the articulated arm gripper. The other articles which are poured from the intermediate buffer platform into the order loading implement (first group) can be poured before or after the article picked directly into the order loading implement (second group).
In order to adapt the picking system for automated picking to different types of storage and order loading implements (e.g., different materials, dimensions, partitions within the loading implements), it is advantageous to provide a gripper changing station. The control device is thus able to deposit the articulated arm gripper attached to the kinematic unit at the gripper changing station using the kinematic unit, depending on the type of the storage loading implement or depending on the type of the order loading implement, and is able to actuate a mechanism which attaches another suitable articulated arm gripper from the gripper changing station to the kinematic unit. It is also possible to conduct only a change of articulated arm grippers which are already attached to the kinematic unit. For example, the control device could adjust the articulated arm gripper according to the type of the storage loading implement and of the order loading implement, as a function of the ratio of article dimension to loading implement dimension, using a revolver device.
Hereinbelow, further advantageous embodiments of the system according to the invention are explained in further detail on the basis of the figures.
In a storage of the picking system 1, which is not illustrated in further detail in
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Depending on the type of loading implement, the longitudinal arm may also be designed so as to be five times or twenty times as long as the articulated arm in order to reliably reach all gripping points in the storage loading implement LLH and to pick up the article P reliably even in case of inaccessible locations of the article P to be picked. In
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It may be mentioned that the gripper changing station might also be implemented in such a way that two or several grippers are attached directly to the kinematic unit K. For example, they might be attached to the kinematic unit K by means of a revolver fixture, wherein one of those grippers at a time would be rotated into the operating position and would be actuated by the control computer for gripping articles P.
Furthermore, in
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The angle of articulation W and the angle of rotation DW of the articulated arm gripper 6 about the longitudinal arm 8 thereof are thereby adjusted such that the articulated arm 9 is precisely vertical to the selected surface. In doing so, the supports 13 abut against the surface of the package at the support points AP. The larger the supporting surface AF on the surface of the article P as determined by the support points AP, the more reliably is the article P held by the vacuum gripper S. In this way, the article P can be picked up by the articulated arm gripper 6 with a maximum gripping force.
The control computer determines the control of the movement of the articulated arm gripper 6 by applying a collision prevention algorithm. When the articulated arm gripper 6 is brought close to the article P and the sucked article P is removed with the articulated arm gripper 6, the control computer thereby takes into account the dimensions of the bent articulated arm gripper 6 and of the sucked article P in order to avoid a collision with the container wall BW or the articles P remaining in the storage loading implement LLH.
Now it is particularly advantageous that the supports 13 of the articulated arm gripper 6 are designed so as to be adjustable. The distance between the supports 13 is determined by the control computer when it has been decided on which surface of the article P the vacuum gripper S will pick up the article P. In
Depending on how much space there is in the storage loading implement LLH filled with the articles P for picking up the article P to be picked which has been selected by the control computer (the control device), the control computer can move the vacuum gripper S to the selected surface of the article P according to different actuation runs. If there is relatively little space for the articulated arm gripper 6 for picking up the article P, since the article P is hard to reach, it has turned out to be advantageous if the kinematic unit K positions the articulated arm gripper 6 directly in front of the article P to be picked up, with the articulated arm 9 oriented in the direction of the longitudinal arm 8 (angle of articulation W=180 degrees). The articulated arm 9 is bent about the angle of articulation W present by the control computer only in this position of the articulated arm gripper 6 as a final positioning operation before suction is applied to the article P. In this way, the articulated arm gripper 6 can advantageously be positioned also in very inaccessible places in the storage loading implement LLH for picking up an article P.
However, if the article P in the storage loading implement LLH is freely accessible for the articulated arm gripper 6, the time for picking the article P from the storage loading implement LLH into the order loading implement ALH can be reduced in that the articulated arm 9 is bent about the angle of articulation W already during the positioning of the articulated arm gripper 6 by the kinematic unit K. The angle of rotation can be adjusted to the angle of rotation DW already during the positioning of the articulated arm gripper 6 by the kinematic unit K independently of the selected actuation run, since the interfering contour of the articulated arm gripper 6 is thereby not enlarged. As a result of this chronologically parallel adjustment of the kinematic unit K and of the articulated arm gripper 6, the throughput of the picking system 1 can be increased and the picking system 1 can thus be made more economical.
In
It may be mentioned that, for example, a platform with a pushing device, a plate which is pulled away from under the articles P, a funnel-shaped chute including a flap control or a sliding device including a flap control might also serve as an intermediate buffer. Furthermore, the number of two intermediate buffers is to be understood only as exemplary, since any number of intermediate buffers might be provided for shortly depositing articles P to be picked. It has turned out to be particularly advantageous if individual shock-sensitive articles P to be picked or articles P which, due to their size or their weight, are the first ones to be placed into the order loading implement ALH are picked by the articulated arm gripper 6 directly into the order loading implement ALH. The other articles P poured from the intermediate buffer platform 16 into the order loading implement ALH (first group) can be poured into the order loading implement ALH before or after the article P picked directly into the order loading implement ALH (second group).
It may be mentioned that the joint of the articulated arm gripper can be designed as a ball joint, as an integral hinge or also according to another type of joint.
The actuating elements of the articulated arm gripper can be designed pneumatically, hydraulically with single- or also double-acting cylinders. Likewise, it would be possible to ensure the actuation of the articulated arm from a remote servomotor via a cable pull or a rod assembly. Furthermore, sensors might be provided on the articulated arm gripper which monitor both the swivelling movement and the gripping function.
It may be mentioned that the gripper might be formed also by another type of gripper. For example, a clamping gripper might be provided which removes the articles P from the storage loading implement by a frictional connection.
It may be mentioned that more than one article at a time could also be picked with the gripper.
It may be mentioned that the kinematic unit might be implemented by a delta kinematics, but also by a robot arm or another mechanism known to a person skilled in this field.
Number | Date | Country | Kind |
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A 786/2011 | May 2011 | AT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP12/58971 | 5/15/2012 | WO | 00 | 11/13/2013 |