DE102006015689B4 - System and method for controlling a conveyor system using computer-aided image recognition - Google Patents

Abstract

A method for controlling a conveyor technology (20, 34, 38) of a commissioning system (10) in order to convey a conveyed item (12, 14) at a predetermined time in a main conveying direction to a predetermined location, comprising the following steps: - Continuous acquisition of current information State images of predetermined areas of the conveyor technology (20, 34, 38) by means of a camera (50-64), in particular by means of a video camera, which is preferably arranged vertically above the conveyor technology (20, 34, 38); - Evaluation of a status image by a To determine the actual position of the conveyed material in the predetermined region of the conveyor route; - to carry out a target-actual comparison for the actual position; - to generate a control signal based on the target-actual comparison result, and - to output the control signal to an actuator, in particular to an input / ejection device, a scanner, a stopper, a switch, a slide, a speed-controlled conveyor technology segment or a stowage device The method is characterized in that the area of the conveyor technology (20, 34, 38) captured by the camera is divided into several segments, each of which can be activated at different speeds, so that each segment is activated at a speed that The closer the segment is arranged relative to a conveyed goods jam, the smaller the segments can be controlled such that individual segments are switched off if it is determined on the basis of the status images of the camera (50-64) that the corresponding segments do not transport any conveyed goods

Description

The invention relates to a control system for conveyor systems, in particular for a commissioning system, in which conveyed goods are conveyed by means of a conveyor system.

It is known to control conveyor and picking systems automatically with a PLC (programmable logic controller) or with a computer-based unit. The signals that indicate trigger-relevant changes in state are conventionally transmitted to a controller, in particular to a warehouse management computer, using light barriers or light sensors. The controller outputs signals to actuators in accordance with known algorithms in order to control the conveyor technology accordingly.

E.g. Light-dark changes in state are detected with light barriers or light buttons. In the case of accumulation roller conveyor systems, the arrival of a conveyed item (carton, container or other piece goods) is detected at a predetermined point, whereupon the drive of an assigned conveyor system segment is stopped and the conveyor system segment, for example, performs a stowage function. In a similar way, scanners are activated, stop devices are extended, switches are switched, or material transfers are initiated.

In the following, the term "conveyor technology" will be understood to mean a conveyor system that allows goods to be moved in limited operating areas, such as e.g. in a picking system, or generally in a warehouse. The term conveyor technology will be understood in a broader sense to mean the process design when operating the conveyor systems. Materials handling elements are e.g. conveyor belts, roller conveyors, overhead conveyors, belt belts etc.

Articles to be picked are kept in so-called storage containers, but can also be transported as individual items. The items are placed in a so-called order container from the storage containers by a picking person at a picking station. The order containers are loaded with the articles according to a picking order. As soon as an order container has been completely picked, it is usually conveyed to a so-called shipping station in order to be delivered.

Problems have often occurred in the past when using light sensors and light barriers to detect conveyed goods, particularly containers and general cargo. With light barriers, for example, it cannot be recognized whether two containers are in direct succession, i.e. with no space between them. For the light barrier, it appears as if a single elongated item is being conveyed. This is particularly problematic when an infeed or outfeed device of the conveyor technology is to be controlled with the light barrier. In this case, it is not possible to steer both goods in the right direction, since it is not possible to differentiate between them.

Furthermore, a light barrier cannot detect whether two goods are being transported side by side. Here again problems can arise when controlling actuators in conveyor technology, e.g. the above-mentioned infeed and outfeed device.

In order to maintain a high throughput in the order picking system, it is necessary to move the goods to be conveyed at a relatively high average speed. However, the conveyor speed depends, among other things. on the dimensions and weight of the material being conveyed. For example, high-rise goods cannot be steered around a curve as quickly as flat goods. Heavy goods in particular are more difficult to brake than lighter goods due to their inertia. All of these factors must be taken into account when controlling the conveyor technology.

Another disadvantage of conventional light sensors and light barriers is that they cannot be used to identify the type or type of material to be conveyed.

It is also disadvantageous that light barriers and buttons cannot always be positioned in the required places. For example, positioning in pushover areas or in the area of switches is not possible.

Another disadvantage is that a light barrier can only provide information about the state of the conveyor technology that prevails at the location of the light barrier itself. Changes in state locally in front of or behind the light barrier cannot be detected with it. This means that it is not possible to plan ahead or check control commands that have already been carried out with light barriers.

The publication DE 199 30 019 A1 relates to a method and a device for controlling the transport of items to be cleaned on a transport path with the aid of handling means.

The publication DE 690 03 645 T2 relates to a device for positioning products in fixed positions when they move in a row on a conveyor belt by closer to each other or further away from each other in the desired distance.

The publication US 2002/0188377 A1 relates to a handling system and in particular to a method and a device for separating articles and for creating a controlled gap between the articles.

The publication DE 102 26 673 A1 relates to a device for conveying and processing individual items along a conveyor line which is formed by a plurality of successive conveyor devices and along which at least one processing station is arranged.

The publication JP H07-206132 A relates to a conveying device in which several conveying means are provided along a conveying direction.

The publication US 2005/0246056 A1 relates to a material handling system for the packaging industry.

It is therefore an object of the present invention to provide a device and a system for controlling a conveyor technology, in particular in a picking system, which are improved over the known methods. In particular, the conveyor technology should be able to be controlled dynamically with regard to the conveyor speed. Advantageously, a dynamic accumulation function and a need-based shutdown of those conveyor technology sections should be possible in which there is no material to be conveyed in order to save energy.

This object is achieved with the objects as defined in the independent claims.

According to a first embodiment, cameras are used to record current state images. In contrast to light switches or push buttons, the use of cameras enables the detection of larger areas of conveyor technology. Existing and non-existing distances between conveyed goods can be determined in advance before the corresponding conveyed goods pass an actuator. The speed can be better regulated on the basis of this information about the upstream state. The conveyor technology can be accelerated or braked, and at different speeds at different points by using conveyor technology segments, in particular motor-driven conveyor rollers.

According to a further preferred embodiment, a dynamic accumulation function takes place in that conveyor segments located upstream of an accumulation are operated such that the segments are operated at an ever lower speed, the closer they are to the location of the accumulation.

• 1 zeigt eine schematische Draufsicht auf ein Kommissioniersystem gemäß der vorliegenden Erfindung;
• 2 zeigt mehrere Fördertechniksegmente beim Ausführen einer dynamischen Staufunktion;
• 3 zeigt ein schematisches Blockdiagramm eines Lagerverwaltungsrechners gemäß der vorliegenden Erfindung; und
• 4 zeigt ein schematisches Flussdiagramm des Verfahrens gemäß der vorliegenden Erfindung.

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description.

• 1 shows a schematic top view of a picking system according to the present invention;
• 2nd shows several conveyor technology segments when performing a dynamic accumulation function;
• 3rd shows a schematic block diagram of a warehouse management computer according to the present invention; and
• 4th shows a schematic flow diagram of the method according to the present invention.

In 1 is a picking system 10th shown according to the invention. The order picking system 10th has a large number of picking modules, which can be expanded to include other modules that are not explicitly explained here. Likewise, some of the modules could be left out. The attachment 10th according to the 1 thus represents only an exemplary embodiment, but is not limited to this specific form.

In the picking system 10th storage containers and order containers are transported, which are generally referred to below as containers 12th can be designated. Filled containers 12th are in the 1 shown in dark. Empty containers 12th are in the 1 shown brightly. Furthermore, general cargo 14 promoted, which are indicated schematically as circles here. General cargo 14 can also be in containers 12th be stored. The containers 12th are on container shelves 16 in a storage area 17th stored. In the upper part of the 1 Carousels are shown as examples, which have a large number of storage spaces for containers 12th which are arranged on top of each other in several levels. The carousel 16 can be in the direction of an arrow 18th move. At the front of the carousel 16 is a lift 19th provided that is height adjustable so that container 12th can be fetched from or delivered to different levels.

The lift 19th can have several load suspension devices. With the help of the lift 19th as mentioned above, the containers 12th from the front of the carousel 16 picked up and sent to a conveyor system 20 delivered or from this for storage in the carousel 16 added. The conveyor technology 20 can be implemented, for example, by a roller conveyor, as is the case with an arrow 22 is indicated as an example.

About conveyor technology 20 , which is shown here as a self-contained loop, are the containers 12th to order pickers 24th transported to the respective picking stations 26 work. At the in 1 shown picking system, the principle "goods-to-man" is realized. The picking person 24th hardly needs to be at the picking station 26 move. The items to be picked are placed in the storage containers 12th to the picking person 24th transported.

The in 1 shown picking station 26 comprises on one side of a picking aisle 27 in which the picking person 24th can move a large number of picking shafts ("pick-to-tote") into the items to be picked from the conveyor technology 20 to the picking station 26 delivered items are picked. The picking shafts have an opening and closing mechanism at their lower vertical end. In the open state, the articles picked in this way fall onto a collecting belt arranged centrally under the picking shafts 30th or a webbing 30th . The one on the tape 30th existing articles become a transfer point 32 promoted. At the transfer point 32 using a further conveyor technology 34 , which can be, for example, another motorized roller conveyor or a belt conveyor, containers 12th for picking up the items from the conveyor 30th transported.

The picking person 24th can also be at the picking station 26 from the picking shelves opposite the picking shafts 36 Items in containers 12th pick that by means of a separate or on the shelf 36 self-managed further conveyor technology 38 to get promoted. At the in 1 The picking rack shown can be a so-called flow rack, which, relative to the picking station 26 , from behind via a feed alley 40 from a storage and retrieval machine (RBG) 42 is equipped with, for example, Euro pallets. The order picker 24th can then load larger batches of items that, for example, are not in the picking shafts 24th fit, remove the euro pallets and put them in containers 12th give. The containers 12th are then by means of conveyor technology 38 either by the picking person 24th on the tape 30th provided by the conveyor technology 38 even on the tape 30th transported or transported to another location, such as to another picking station or directly to a shipping station.

The RBG 42 can be in the direction of an arrow 44 in the feed alley 40 proceed. To the flow racks 36 Loading pallets or other containers can be a pallet store opposite the picking rack 46 be provided.

The conveyor technology 34 , which is also the transfer point already mentioned 32 is included in the exemplary system 10th in the lower part of the 1 with an arrow 49 redirected. In this area is the conveyor technology 34 exemplary in several segments S1-S5 divided. Each of these elements is part of an accumulation conveyor line and is operated by means of several separate cameras 50 supervised. Alternatively, fewer cameras can be used. A single camera is also exemplary 52 shown that can capture the entire longitudinal length of the accumulation conveyor.

There are other cameras at other relevant locations 54 to 62 arranged. Any of these cameras 50 to 62 monitors an area assigned to it 66 to 80 . The areas 66 to 80 are in tax-relevant areas of conveyor technology.

For example, the cameras are located 50 and 52 in the fields of 66 or the area 68 that is relevant for the exercise of the congestion function. The camera 54 with their assigned area 76 monitors a section of conveyor technology, for example 34 which is the transfer point 32 is upstream. The camera 56 with their assigned area 74 monitors the transfer point 32 itself. The camera 58 monitors the area 72 to determine whether the conveyed or general cargo is correctly oriented relative to the longitudinal axis of the conveyor system itself. In the 1 is in the area 72 a container 12th arranged at an angle. With the help of the images from the camera 58 this condition can be recognized and, for example, in the area 70 by means of (side) sliders 71 correct. These correction operations can also be done using the camera 60 be monitored. Correct alignment of the material to be conveyed is particularly important if the length of the material to be conveyed is longer than the width of the conveyor technology, in order to prevent the material to be tilted in areas of the conveyor technology where there are changes in direction of the conveyor technology itself, such as in curves.

However, goods with smaller widths should always be correctly aligned.

In the fields of 78 and 80 of the cameras 64 and 62 become deflection devices of conveyor technology 38 supervised. With the help of the images from the cameras 62 and 64 can infeed and outfeed devices (here only indicated by arrows) of the conveyor technology 38 can be controlled. With the help of the camera 62 but not only the location of the Monitor deflection device, but also the entire length of the conveyor system 38 along the picking shelf 36 . In this way, the utilization of this section of conveyor technology can be 38 monitor and, if necessary, visualize it. The same applies to that from the camera 64 monitored area 78 . The area 78 can span the entire length of the anthology 30th extend.

In general, all information from the cameras can be visualized.

The cameras 50 to 64 transmit their pictures to a superordinate warehouse management computer (LVR) 90 . The cameras are there 50 to 64 via connecting lines 102 eg with a data bus 100 , such as a PROFIBUS®, or via an ethernet, WLAN, USB or other fixed or wireless buses with the LVR 90 in connection. However, the cameras can also be connected directly to the LVR, as exemplified by a line 104 is indicated. Especially with cameras that are difficult to access locally, the signal can also be transmitted wirelessly, as indicated by arrows 106 is indicated. The conveyor technology segments too S1 to S5 can be connected to the warehouse management computer in this way. An example is a connection via a line 108 shown.

In 2nd is an accumulation roller conveyor 109 schematically illustrated. The accumulation roller conveyor 109 can be identical to that in 1 be shown. It comprises five segments here S1 to S5 . A main direction of funding runs in the 2nd from left to right, as indicated by an arrow.

In the area of the segment S5 a jam has formed. This is done either by a camera assigned to this segment or by a higher-level camera (cf. camera 52 in 1 ) detected. The corresponding camera delivers an image to the LVR 90 who uses appropriate image processing software to recognize that there are four containers in the segment S5 are located. In the in 2nd The example shown means four containers 12th a jam within the same conveyor technology segment. In order not to let other containers drive onto this traffic jam, the LVR 90 Control commands to the upstream segments S1 to S4 to reduce their speed. The speed of the individual segments is preferred S1 to S4 set in such a way that the closer the corresponding segment is to the traffic jam, the lower the speed.

Similarly, the LVR 90 switch off certain conveyor segments if it is determined from the images supplied by the cameras that the corresponding segments do not transport any goods. However, if the transport of a material to be conveyed is detected by an upstream camera, the conveyor segments located downstream can be reactivated accordingly, with a corresponding delay. In this way, the conveyor technology can be controlled as required. The big advantage here is the saving of energy. The conveyor technology is only operated if there are actually goods to be conveyed on the conveyor technology.

The dynamic traffic jam function explained above makes it easier to avoid traffic jams. Conversely, traffic jams can be resolved more quickly if conveyor segments located downstream of the traffic jam are operated at an ever greater speed the further the segment is located downstream of the traffic jam.

By using the camera, an actual state of the conditions on the conveyor technology can be determined, which is not only extended to the location of the camera itself, but also to entire conveyor technology areas. With the help of the cameras, it can be easily recognized whether, for example, several conveyed goods are transported directly one behind the other, which could not be detected by a simple light barrier due to the lack of a distance between the conveyed goods. The images generated by the cameras can also be used to visually display the load on the picking system. In this way, the utilization of the system can be visually represented by an operator who is entrusted with the task of monitoring the overall system. This also enables remote monitoring and remote maintenance. It goes without saying that the cameras should not be used to monitor the picking person himself, but only to monitor the load status of the conveyor technology.

The cameras can be arranged both above the conveyor system and laterally to the conveyor system. A lateral arrangement makes it possible to determine the height of the transported piece goods. This information is particularly relevant when very high goods are being transported. Tall goods tend to fall over at high conveyor speeds. The conveying speed can therefore also be set depending on the geometric height of the conveyed goods.

In 3rd Figure 3 is a schematic block diagram of the LVR 90 of the 1 and 2nd shown. The LVR 90 includes a database 10th , in which algorithms for image processing, conveyor technology control and the like are stored. The LVR also includes 90 a CPU 112 , a variety of interfaces 114 (eg USB) with connections 115 can be connected to communicate with the various actuators and the cameras. The LVR 90 can also have special image processing modules 116 and target-actual comparison module 118 (in the form of software or hardware).

In 4th the method according to the present invention is shown schematically in the form of a flow chart. In a first step 120 up-to-date status images of conveyor technology are recorded. In a further process step 130 the image processing takes place. Then in one step 140 a target-actual comparison was carried out. For this purpose, the captured images are compared with previously calculated or read states, which should ideally prevail in the picking system. If the comparison of the target state with the actual state shows that there are no deviations between the two, the step becomes 120 Returned or corresponding control signals are output to downstream actuators, the further (pre-planned) transport of the goods through the picking system 10th regulate. If there are deviations between the actual state and the target state, other actuators can be actuated to correct this deviation.

A great advantage of the invention can be seen in the fact that large areas of conveyor technology can be monitored quickly and easily. In particular, in the case of errors, it can be determined in advance how best to react to them. Conveyed goods can be positioned correctly again. Conveying goods moving in succession can be separated. The jam function can be designed dynamically. Conveyed goods can be recorded and documented by type and number. It is possible to check the processing of picking orders. With e.g. The color of the order picking containers can also be differentiated and thus directed to their destination. Containers can be provided with corresponding codes that can be read by the cameras in order to control downstream actuators in such a way that the corresponding containers are directed to predetermined destinations (storage rack, picking station, shipping station, etc.). It goes without saying that not only cameras, e.g. Video cameras can be used that work in the visible area. Cameras for the detection of other wavelengths can also be used.

Claims (9)

A method for controlling a conveyor technology (20, 34, 38) of a commissioning system (10) in order to convey a conveyed item (12, 14) at a predetermined time in a main conveying direction to a predetermined location, comprising the following steps: - Continuous acquisition of current information State images of predetermined areas of the conveyor technology (20, 34, 38) using a camera (50-64), in particular using a video camera, which is preferably arranged vertically above the conveyor technology (20, 34, 38); - Evaluation of a status image in order to determine an actual position of the material to be conveyed in the predetermined region of the conveyor line; - performing a target-actual comparison for the actual position; - Generating a control signal based on the target-actual comparison result, and - Outputting the control signal to an actuator, in particular to an input / ejection device, a scanner, a stopper, a switch, a slide, a speed-controlled conveyor technology segment or a stowage space, whereby the method is characterized in that the area of the conveyor technology (20, 34, 38) detected by the camera is divided into several segments, each of which can be controlled at different speeds, so that each segment is controlled at a speed that is all the lower is, the closer the segment is arranged relative to a conveyed goods jam, the segments being controllable in such a way that individual segments are switched off if it is determined on the basis of the status images of the camera (50-64) that the corresponding segments do not transport any conveyed goods Procedure according to Claim 1 , further comprising: storing recorded status images, target-actual comparison results and / or control signals for logging. Procedure according to Claim 1 or 2nd , in order to carry out the target / actual comparison, target positions are calculated or read in advance. Method according to one of the preceding claims, wherein during the evaluation it is determined whether the conveyed item is correctly aligned relative to the main conveying direction, and wherein, if the conveyed item is not correctly aligned, the control signal is output to at least one adjusting device in order to align the conveyed item correctly. Method according to one of the preceding claims, wherein during the evaluation it is determined whether a plurality of conveyed goods are conveyed directly one behind the other in order to be able to separate them. Procedure according to Claim 5 , wherein the control signal, if it has been determined that a plurality of conveyed goods are conveyed directly one behind the other, is output to at least one stowage location in order to temporarily stop at least one of the conveyed goods, so that at least the first conveyed good is at a distance from a conveyed goods following it. Procedure according to Claim 6 , with geometric lengths of the conveyed goods being determined in order to be able to control a corresponding number of accumulation conveying stations. Method according to one of the preceding claims, wherein during the evaluation it is determined whether a plurality of conveyed goods are conveyed next to one another relative to the main conveying direction, in order to control sliders in such a way that the conveyed goods conveyed next to one another are arranged one behind the other. Picking system with a conveyor system (20, 34, 38), at least one actuator and a control unit (80) which is adapted to the method according to one of the Claims 1 to 8th perform.

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