Monitoring system and monitoring method for a storage space

Abstract

A monitoring system and a computer implemented method for monitoring the placement or removal of items (1) in a storage space (2) is described. The monitoring system comprises a control unit (7) configured to be in communication with a communication assembly (6). The control unit (7) is configured to obtain a unique identification code for at least one scanner (4), configured to transmit positioning signals comprising the unique identification code. The control unit (7) is configured to determine a radio based tracking data (11) for the at least one scanner (4) based on the positioning signals received by radio based anchor units (9), and to identify at least one person (12) in the registered images and to determine image based tracking data (13) based on the images registered by at least one LIDAR sensor. The control unit is configured to retrieve a set of scanned item data from the at least one scanner (4) and to determine whether the image based tracking data (13) matches the retrieved set of scanned item data.

Description

[0001] MONITORING SYSTEM AND MONITORING METHOD FOR A STORAGE SPACE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a monitoring system for monitoring the placement or removal of items in a storage space. The present disclosure also relates to a computer implemented method for monitoring the placement or removal of items in a storage space, and to a computer program product on which is stored a computer program comprising instructions, which when executed by a processor makes the processor perform the method.

[0004] BACKGROUND ART

[0005] Retail businesses have a desire to prevent shoplifting. Clothes stores usually put alarm tags on their clothes to prevent shoplifting. The use of alarm tags makes it considerably more difficult to shoplift. In many types of shops such as in, e.g., grocery stores, it is not practically possible to use alarm tags. This is also true for items of less value in other types of retail stores. Until a few years ago, most grocery stores had cashiers that registered all groceries that the customers had collected in the store. To prevent people from shoplifting by putting groceries in their bags and pockets, many grocery stores rely on manually monitored surveillance cameras.

[0006] In recent years, it has become increasingly common with self-scanning in grocery stores. In one alternative for self-scanning, the customers pick up a scanner when entering the store. The customers have to register when they pick up the scanner. In this way, each scanner is connected to a unique customer. When the customer is in the store the customer scan a label on each item that is collected. When the customer is finished, the customer puts the scanner in a reader, which collects the information on the scanned items. The customer then pays for the scanned items. A problem with such a self-scanning system is that shoplifters may omit scanning some of the collected items. To minimize this problem many stores performs random checks when the customers are about to pay.

[0007] A related problem exists for storage spaces used for storing equipment, which is to be used short periods of time on a regular basis. An example of such a storage space is at a ski rental business. After each use, the items are to be stored in predetermined positions. In present businesses of this type the items are registered both when they are handed out to customers and when they are returned. A problem is that errors may be made by the person handling the items at the storage space. SUMMARY OF THE INVENTION

[0008] An objective of the present disclosure is to provide a method and a monitoring system for monitoring the placement or removal of items in a storage space, which is an alternative to the methods and monitoring systems of the prior art.

[0009] Another objective of the present invention is to provide a method and a monitoring system for monitoring the placement or removal of items in a storage space, which may be arranged in a storage space at a low cost.

[0010] Another objective of the present invention is to provide a method and a monitoring system for monitoring the placement or removal of items in a storage space, which is suited for automatic monitoring without the need for human operators.

[0011] At least one of these objectives is fulfilled with a according to the independent claims.

[0012] Additional advantages are provided with the features of the dependent claims.

[0013] According to a first aspect, a monitoring system is provided for monitoring the placement or removal of items in a storage space. The monitoring system comprises a communication assembly configured for communication with at least one scanner for scanning of item data, and a control unit configured to be arranged in communication assembly, wherein the control unit is configured to obtain a unique identification code for the at least one scanner. The at least one scanner comprises a radio based positioning unit configured to transmit positioning signals comprising the unique identification code. The communication assembly is configured to receive the positioning signals from the radio based positioning unit. The monitoring system also comprises at least one LIDAR sensor, which is configured to be arranged for registering images of the storage space. The control unit is configured to determine a radio based tracking data for the at least one scanner based on the positioning signals received by the radio based anchor units. The control unit is further configured to identify at least one person in the registered images and to determine image based tracking data for the at least one person based on the registered images. The control unit is further configured to determine image based tracking data for the at least one scanner by matching the radio based tracking data with the image based tracking data, to retrieve a set of scanned item data from the at least one scanner, corresponding to the items which have been scanned with the at least one scanner, and to determine whether the image based tracking data matches the retrieved set of scanned item data. In a monitoring system according to the first aspect, the image based tracking data is connected to the movement of the scanner. The radio based tracking data is correlated with a specific scanner and defines the movement of the scanner as a point in space. The radio based movement tracking data does not contain any information on rotational movement of the scanner. It is easier to obtain a higher accuracy of the image based tracking data with low cost equipment, i.e. , a low cost LIDAR sensor. Also, the image based tracking data may contain data not only as the movement of a point in space but may also contain information on the rotational position of a person and shape of the person, i.e., how the arms and / or legs of the person are positioned. According to the first aspect, the control unit is configured to determine whether the image based tracking data matches the retrieved set of scanned item data. As the image based tracking data typically has a better accuracy than the radio based tracking data the determination on whether the image based tracking data matches the retrieved set of scanned item data, may be performed with a higher accuracy. Also, the use of tracking data enables additional information about the position and shape of the person.

[0014] The positioning signal may be configured in many different ways. According to one alternative the scanner may determine its position using UWB or WiFi or any other method. The radio based positioning unit may then be configured to transmit positioning signals comprising the position of the scanner as well as the unique identification code. The position is determined in a coordinate system of the storage space. The UWB or WiFi system used for the positioning do not have to be part of the monitoring system per se.

[0015] According to an alternative the communication assembly may comprise at least two radio based anchor units configured to be arranged at predetermined positions in the storage space in communication with the control unit. With such a communication assembly the scanner sends a positioning signal comprising only the unique identification code. The position of the scanner is determined by the control unit based on the positioning signals received by the radio based anchor units. To avoid fraud it is advantageous that the communication assembly comprises at least two radio based anchor units so that the control unit may determine the positions of the scanner.

[0016] The unique identification code may be obtained in many different ways depending on how the monitoring system is configured.

[0017] According to one alternative, the control unit may be configured to register any unique identification code that is received with the positioning signals by the radio based anchor units. According to this alternative, the scanner sends the positioning signals with a unique identification code. The unique identification code is stored in the scanner. The scanner may be a dedicated scanner that is associated with the monitoring system. Such a dedicated scanner may have the unique identification code stored on the scanner at initiation of the monitoring system. Such a dedicated scanner may transmit the positioning signals continuously even if they are not in use, or at least after being picked up by a user. Radio based tracking data is determined for all scanners that transmit the positioning signals.

[0018] As an alternative to a dedicated scanner, the scanner may be a mobile device, such as a mobile phone, a personal digital assistant or similar. By having the scanner as a mobile phone no dedicated scanners have to be used at the storage space. The user may set the mobile phone in a sending mode in which positioning signals are transmitted from the mobile phone, which positioning signals comprise the unique identification code. The unique identification code may be the telephone number or a customer number or similar. Radio based tracking data is determined for all scanners that transmit the positioning signals.

[0019] The control unit may be configured to receive an initiation message via the communication assembly, to obtain a unique identification code for the scanner corresponding to the initiation message, and to determine radio based tracking data based only on positioning signals comprising a unique identification code corresponding to an initiation message.

[0020] In the case of dedicated scanners, the communication assembly may comprise a keyboard and a screen and / or a device for near-field communication and or a device for radio communication. The user may enter his personal information at the communication assembly or scan a credit card or the like at the device for near-field communication. The control unit may then provide access to a specific scanner with a specific unique identification code and start determining radio based tracking data for the specific scanner.

[0021] In case the scanner is a mobile device, the initiation message may be enabled by the user initiating a message from the phone. This may be done in many different ways. When the control unit receives the initiation message it may control the communication assembly to send the unique identification code to the mobile device or may, alternatively, request the mobile device to send the unique identification code to the control unit via the communication assembly. The communication with the communication assembly may be performed using a suitable type of communication technique, such as, e.g., near-field communication, or radio communication such as Wi-Fi. Thus, the control unit may be configured to determine the unique identification code and to control the communication assembly to send the unique identification code to the scanner.

[0022] The input of information at the communication assembly may be performed by manual input of information at a keyboard, by using a smartcard, a credit card, a tag or a mobile phone. Other possible methods include face recognition, and fingerprint recognition. The input of information may be done using near-field communication or a keyboard. It is possible to have the communication assembly configured for communication using Bluetooth or WiFi or other communication techniques.

[0023] The registration of placement or removal of items in the storage space may be done at any time before, during or after the scanning of items in the storage space. However, the communication assembly is preferably configured for the person to be close to the communication assembly when registering and is preferably arranged close to the entrance / exit of the storage space.

[0024] The radio based tracking data and / or the image based tracking data may comprise positions as a function of time. This is a straightforward way for storing of the tracking data. There are other ways of storing the tracking data. One example of another way of storing the tracking data is to store the tracking data as vectors. Preferably, both the radio based tracking data and the image based tracking data comprise positions as a function of time. With the tracking data in said form the correlation of the radio based tracking data with the image based tracking data may include probability calculations to find the best match between different tracking data. When correlating image based tracking data with radio based tracking data there are points that may be used to narrow down the number of image based tracking data and radio based tracking data. One point is the point of registration of placement or removal of items and another point is the point where the registration is terminated. Image based tracking data and radio based tracking data may be identified based on the point at which registration is initiated. The registration in the storage space is typically performed close to the communication assembly, when the person enters the storage space or when the person is finished and is to leave the storage space. Either the reason for this is that the communication assembly either requires the person to enter information manually or that the communication assembly requires the person to be close to the communication assembly. Thus, if this is the case only image based tracking data and radio based tracking data, which have a position close to the communication assembly at the time of registration, are relevant to take into account.

[0025] The monitoring system may comprise a memory. The determination of whether the image based tracking data matches the retrieved set of item data may comprise the steps of retrieving from the memory the storage positions of the items corresponding to the item data in the set of scanned item data, identifying positions in the image based tracking data, from which positions the person has been within a predetermined distance for at least a predetermined period of time, as resting positions, and determining whether each resting position corresponds to a retrieved storage position of an item. The resting positions are positions at which the person had an opportunity to place or remove items in a storage space. If the person is at a specific position for a shorter time, the person does not have enough time to place or remove an item. If the person has not been within the predetermined distance for at least a predetermined period of time, it is deemed that the person has not had time to place or remove an item.

[0026] If it is determined that each resting position corresponds to a retrieved storage position of an item, the monitoring system may be configured to take no action. However, if it is determined that one or more resting positions does not correspond to a retrieved storage position of an item the control unit may determine whether the resting position corresponds to a storage position of any item in the storage space. If this is the case, the monitoring system may provide an alert. If this is not the case the monitoring system may be configured to take no action. An example of a reason for a resting position is that the person checks a shopping list or talks to another person. If the person is at a too large distance from any storage position, the person has no possibility to place or remove any items.

[0027] The image based tracking data may also comprise information on positions of the arms and / or limbs of the persons. This increases the possibilities to identify fraudulent behavior. If, for example, the arms of a person at a resting position are directed away from any storage positions the control unit may be configured to take no action.

[0028] If the image based tracking data may also comprise information on positions of the arms and / or limbs of the persons and if it is determined that a resting position does not correspond to a retrieved storage position of an item, the control unit may be configured to determine for said resting positions, whether a hand has been within a predetermined distance from any storage position. This increases the possibility to make the correct decision regarding a suspected fraudulent behavior.

[0029] The step of retrieving a set of scanned item data may be performed when the control unit has received an end message. The end message may be from the scanner or may be entered at a keyboard at the communication assembly. This means that all scanned item data is stored temporarily in the scanner. As an alternative, the control unit may be configured to retrieve the scanned item data at multiple occasions.

[0030] The monitoring system may comprise a scanner station in which the scanner is positioned before and after use, comprising an communication assembly for input of user information, wherein the control unit is configured such that when it receives user information input by a user at the terminal, the control unit controls the scanner station to initiate one of the scanners and stores the user information together with the unique identification code of the scanner. The step of retrieving a set of item data may be performed when the scanner has been positioned in the scanner station. The positioning of the scanner in the scanner station is a natural end point for scanning.

[0031] According to a second aspect, a computer implemented method for monitoring the placement or removal of items in a storage space is provided. The computer implemented method comprises the steps of receiving from an communication assembly an initiation signal, and obtaining a unique identification code of at least one scanner for scanning of item data, wherein the at least one scanner comprises a radio based positioning unit configured to transmit a positioning signal comprising the unique identification code. The computer implemented method also comprises the steps of receiving from radio based anchor units, arranged at predetermined positions in the storage space, positioning signals for the at least one positioning unit, receiving from at least one LIDAR sensor registered images of the storage space, determining a radio based tracking data for the at least one scanner based on the positioning signals, and identifying at least one person in the registered images and determining image based tracking data for the at least one person based on the registered images. The computer implemented method also comprises the steps of determining image based tracking data for the at least one scanner by correlating the radio based tracking data with the image based tracking data, obtaining a set of scanned item data from the at least one scanner, corresponding to the items which have been scanned with the at least one scanner, and determining whether the image based tracking data matches the retrieved set of scanned item data.

[0032] The radio based tracking data is correlated with a specific scanner and defines the movement of the scanner as a point in space. The radio based movement tracking data does not contain any information on rotational movement of the scanner. It is easier to obtain a higher accuracy of the image based tracking data with low cost equipment, i.e., a low cost LIDAR sensor. Also, the image based tracking data may contain data not only as the movement of a point in space but may also contain information on the rotational position of a person and shape of the person, i.e., how the arms and / or legs of the person are positioned. According to the first aspect, the control unit is configured to determine whether the image based tracking data matches the retrieved set of scanned item data. As the image based tracking data typically has a better accuracy than the radio based tracking data the determination on whether the image based tracking data matches the retrieved set of scanned item data, may be performed with a higher accuracy. Also, the use of tracking data enables additional information about the position and shape of the person. The positioning signal may be configured in many different ways. According to one alternative the scanner may determine its position using UWB or WiFi or any other method. The radio based positioning unit may then be configured to transmit positioning signals comprising the position of the scanner as well as the unique identification code. The position is determined in a coordinate system of the storage space. The UWB or WiFi system used for the positioning do not have to be part of the monitoring system per se.

[0033] According to an alternative the positioning signals for the at least one positioning unit are received from at least two radio based anchor units, arranged at predetermined positions in the storage space communication assembly may comprise at least two radio based anchor units configured to be arranged at predetermined positions in the storage space in communication with the control unit. With such a communication assembly the scanner sends a positioning signal comprising only the unique identification code. The position of the scanner is determined by the control unit based on the positioning signals received by the radio based anchor units.

[0034] The radio based tracking data and / or the image based tracking data may comprise positions as a function of time. This has the advantages as was described for the same feature regarding the first aspect above.

[0035] The determination of whether the image based tracking data matches the retrieved set of item data, may comprise the steps of retrieving from a memory the storage positions of the items corresponding to the item data in the set of scanned item data, identifying in the image based tracking data positions, from which the person has been within a predetermined distance for at least a predetermined period of time, as resting positions, and identifying whether each resting position corresponds to a retrieved storage position of an item. This has the advantages as was described for the same feature regarding the first aspect above.

[0036] The image based tracking data may also comprise information on positions of the limbs and / or hands of the at least one person. This has the advantages as was described for the same feature regarding the first aspect above.

[0037] If it is determined that each resting position does not correspond to a retrieved storage position of an item, the control unit is configured to determine for said resting positions using the image based tracking data, whether a hand has been within a predetermined distance from any storage position. This has the advantages as was described for the same feature regarding the first aspect above.

[0038] The step of retrieving a set of item data is performed after reception of an end signal. This has the advantages as was described for the same feature regarding the first aspect above. According to a third aspect a computer program product is provided on which is stored a computer program comprising instructions, which when executed by a processor makes the processor perform the computer implemented method according to the second aspect.

[0039] In the following, preferred embodiments will be described with reference to the appended drawings.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 shows schematically in a view from above, a storage space with a monitoring system according to a first embodiment of the invention.

[0042] Figure 2 shows in more detail in a view from above, a person in front of a shelf.

[0043] Figure 3 shows schematically a storage space with a monitoring system according to a second embodiment of the invention.

[0044] DETAILED DESCRIPTION

[0045] In the following description of preferred embodiments, the same reference numeral will be used for the same feature in the different drawings. The drawings are not drawn to scale.

[0046] A monitoring system 100 according to an embodiment of the invention is shown in Figure 1. A monitoring system 100 according to an alternative embodiment is shown in Figure 3. The monitoring system 100 is in both embodiments configured for monitoring the removal of items 1 in a storage space 2. The storage space 2 comprises a number of shelves 3 in which items 1 are stored. In the embodiment of Figure 1 the monitoring system comprises at least one scanner 4 with a unique identification code, i.e. , each scanner 4 has a unique identification code. The scanner is configured to scan item data from the items. The item data is in the form of a machine readable code on each item 1 . The machine readable code may for example be a bar code or a printed number. The monitoring system 100 comprises a scanner station 5, in which the scanner 4 is positioned before and after use, comprising a communication assembly 6, 9. The communication assembly may be configured for input of user information. The communication assembly 6 may for example comprise a card reader or a keyboard (not shown). The monitoring system 100 comprises a control unit 7 in communication with the scanner station 5. The control unit comprises a processor 17, which executes a computer program comprising instructions to thereby configure the control unit 7. The control unit 7 may be configured such that when it receives an initiation signal with user information at the communication assembly 6, the control unit 7 controls the scanner station 5 to initiate one of the scanners 4 and stores the user information together with the identification code of the scanner 4. Such an initiation is suitably followed by alerting the user about which scanner to pick up. Such an alert may be a visible and / or audible signal at the position of the initiated scanner 4 and / or information at the communication assembly 6 regarding the position of the initiated scanner 4. As an alternative, a user may pick up any scanner 4 without entering any user information. Each one of the at least one scanner 4 comprises a radio based positioning unit 8, which is configured to transmit a positioning signal comprising the unique identification code of the scanner 4. The scanner may start transmitting the positioning signal when the user picks it up from the scanner station. In the embodiment of Figure 1 the communication assembly 6 of the monitoring system 100 comprises three radio based anchor units 9 arranged at predetermined positions in the storage space 2. The radio based anchor units 9 are configured to receive the positioning signals from the positioning units 8. The positioning signal may be configured in many different ways. With the communication assembly 6 comprising radio based anchor units 9, the scanner 4 may send a positioning signal comprising only the unique identification code. The position of the scanner 4 is determined by the control unit 7 based on the positioning signals received by the radio based anchor units 9.

[0047] According to an alternative embodiment the communication assembly 6 does not comprise radio based anchor units 9. The scanner 4 may determine its position using UWB or WiFi or any other method. The radio based positioning unit 8 may then be configured to transmit positioning signals comprising the position of the scanner 4 as well as the unique identification code. The position is determined in a coordinate system of the storage space. The UWB or WiFi system used for the positioning do not have to be part of the monitoring system 100 per se but may comprise transceivers at the positions of the radio based anchor units 9 in Figure 1.

[0048] The monitoring system 100 also comprises LIDAR sensors 10, which are configured to register images of the storage space 2. The control unit 7 is configured to determine a radio based tracking data 11 for each scanner based on the positioning signals received by the radio based anchor units. If no initiation signal is sent, the control unit may be configured to determine a radio based tracking data for all scanners sending out positioning signals. The radio based positioning may be implemented in many different ways. One alternative for the implementation is to send out time stamp signals from the radio based positioning unit 8 of the scanner 4 together with the unique identification code. The anchor units 9 determine the time when they receive the time stamp signals. The different reception times is a measure of the different distances to the scanner 4. The dotted line 11 is the radio based tracking data, i.e., the movement of the scanner 4 as registered by the radio based positioning system. A person 12 is carrying around the scanner in the storage space. The control unit 7 is configured to identify persons 12 in the registered images and to determine image based tracking data 13 for each person 12 based on the registered images, i.e., the movement of the scanner 4 as registered by the LIDAR sensors. The control unit 7 is also configured to determine image based tracking data for each scanner by correlating the radio based tracking data 11 with the image based tracking data 13. As the different tracking data correlates it is possible to determine that they correspond to each other. The radio based tracking data 11 and the image based tracking data 13 comprises positions as a function of time, i.e., for each point in time there is a corresponding position registered. Many different methods may be used for the correlation between the radio based tracking data 11 and the image based tracking data 13. The correlation is easier to perform when the person with the scanner has moved a longer distance. One of the reasons for this is that the paths of different persons might be identical for shorter path lengths. Different persons pick up the scanner at the same station and many of the persons might walk from the scanner station 5 directly to the nearest shelf 3. However, the longer the person has walked the larger is the difference between the image based tracking data of the person and the image based tracking data of a different person. Thus, it might be favourable to do the correlation at the end of the person’s path through the storage space. When the person has finished his placement or removal of items in the storage space 2 the person positions the scanner 4 in the scanner station 5. Thus, if the correlation of the image based tracking data 13 and the radio based tracking data 11 is done when the scanner has been placed in the scanner station 5 it is easier to identify which image based tracking data that are relevant for the person holding the scanner 4, i.e., which image based tracking data 13 to compare with the radio based tracking data 11 .

[0049] The control unit 7, when a scanner 4 is positioned in the scanner station 5, is configured to retrieve a set of item data from the scanner 4, corresponding to the items which have been scanned with the scanner 4, and to determine whether the image based tracking data matches the retrieved set of item data. The determination of whether the image based tracking data 13 matches the retrieved set of item data, comprises the step of retrieving from the memory 14 the storage positions of the items corresponding to the item data in the set of scanned item data. The determination also comprises identifying positions in the image based tracking data, from which positions the person has been within a predetermined distance for at least a predetermined period of time, as resting positions 15, and identifying whether each resting position corresponds to a retrieved storage position of an item. In Figure 1 , the person stands in front of the item 1 . If the time in front of the item 1 is above a predetermined time limit, it might be assumed that the person 12 has removed the item 1. If the item 1 is not scanned with the scanner, shoplifting may be suspected. However, there are many reasons for a person to be positioned in front of an item 1 at a shelf 3. One reason might be that there are many similar items on the shelf such as for example sauces of different brands. It might take some time for the person to check and compare the prices on the different sauces and might still decide not to buy anything. After having positioned the scanner in the scanner station 5, the person may be prompted to pay for the scanned items. The payment may be done at the communication assembly 6 or at a separate payment terminal 20.

[0050] If the scanner 4 is a mobile device the retrieval of a set of item data from the mobile device may be performed when the user indicates on the mobile device that no more items are to be scanned. The set of item data may then be sent to the communication assembly 6, either directly using WiFi, Bluetooth or any other method, or indirectly using a cellular net to which the communication assembly and the mobile device are connected.

[0051] To improve the detection of possible fraudulent the image based tracking data 13 also comprises information on positions of the arms 16 of the persons 12. Figure 2a shows in more detail in a view from above, a person 12 in front of a shelf 3 with the persons 12 first arm 16 and second arm 16’, stretched towards the shelf 3.

[0052] Figure 2a shows in more detail in a view from above, a person 12 in front of a shelf 3 with the persons 12 first arm 16 and second arm 16’, stretched towards the shelf 3. An item 1 is placed in the shelf. If it is determined that the resting position shown in Figure 2a does not correspond to a retrieved storage position of an item, i.e. , that the person 12 has not scanned any items positioned on a shelf close to the resting position, the control unit is configured to determine for said resting positions, whether an arm 16, 16’, has been within a predetermined distance from any storage position. The predetermined distance is illustrated by the line 18. As can be seen in Figure 2a the first arm has been within the predetermined distance from the shelf where the item 1 is stored. The second arm 16’ is outside the line 18 but contains a second item that might have been taken from the shelf. These two examples may be used as an indication of fraudulent behavior, i.e., shoplifting and may trigger a control at the checkout. However, these two examples are no clear indication of shoplifting. It is quite common that persons read on the label on the items to be informed on the ingredients. To improve the probability for a correct detection of shoplifting the tracking data, the set of scanned item data, and the outcome of a physical control, may be used to train artificial intelligence. The trained artificial intelligence may then be used to determine whether there is a probability for shoplifting.

[0053] Figure 2b shows a first person 12 and a second person 12’ in a resting position. The arm 16 of the first person is on the shoulder of the second person. Even if the first person 12 is within the predetermined distance as illustrated by the line 18, it might be determined from the arm 16 and the second person that no shoplifting occurred at the illustrated resting position. A monitoring system 100 according to an alternative embodiment is shown in Figure 3. The storage space is a warehouse from which a person may remove items 1 , which are later to be returned. Each item 1 has a dedicated position in a specific shelf 3. In the embodiment of Figure 2b, there is no scanner station with scanners 4, but instead the person 12 brings a personal scanner with a unique identification code. The scanner may be a mobile device such as a mobile phone, and an optional initiation comprises sending an initiation signal from the mobile device to the communication assembly 6. The initiation may result in the control unit obtaining a unique identification code for the scanner. This may be provided by the mobile phone sending an initiation message comprising the unique identification code. The initiation signal is then sent to the control unit 7. Alternatively, the control unit may be configured to determine a unique identification code and control the communication assembly to send the unique identification code to the scanner. As an alternative, if no initiation message is sent, the mobile phone may just start sending the unique identification code. The unique identification code should have a predetermined format and might for example be a telephone number. Optionally, the person 12 may also provide identification information using the communication assembly 6. Alternatively, the identification information may already be stored in the memory 14 together with the corresponding unique identification code.

[0054] When entering the storage space the person may initiate a placement of items in the storage space using the communication assembly 6. The registration of radio based tracking data 11 and image based tracking data 13 may then be performed as was described for the first embodiment with reference to Figures 1 and 2.

[0055] If the person instead places items in the storage space 2, the tracking data may indicate whether the person 12 has placed the item in the correct position. If the person has scanned the item 1 this indicates that the item has been placed in the storage space. However, if the item 1 has been placed in the incorrect position and the person has never stopped at the correct position this is indicative of an incorrect placement. This is illustrated in Figure 3 as the person 12 is in a resting position at a second shelf 3’ with the arms stretched towards the second shelf 3’, while the first shelf 3 is the correct shelf for the item 1 . Before placing the item on the erroneous second shelf, the person scans item data from the item. When the person 12 has finished placing items in the storage space the person 12 sends 15, from the mobile device an end signal to the communication assembly 6, which end signal is then sent to the control unit 7. The control unit then retrieves from the memory 14 the storage positions of the items corresponding to the item data in the set of scanned item data. The control unit also identifying positions in the image based tracking data, from which positions the person has been within a predetermined distance for at least a predetermined period of time, as resting positions 15, and identifies whether each resting position 15 corresponds to a retrieved storage position of an item. As the person 12 has not been at the correct storage position for the item 1 , the resting position 15 does not correspond to the correct position for the scanned item data. In other words, the image based tracking data 13 does not correlate with the retrieved set of scanned item data. If the scanner 4 used is a mobile device the retrieval of a set of item data from the mobile device may be performed when the user indicates on the mobile device that no more items are to be scanned. The set of item data may then be sent to the communication assembly 6, either directly using WiFi, Bluetooth or any other method, or indirectly using a cellular net to which the communication assembly and the mobile device are connected. The described embodiments may be amended in many ways without departing from the scope of the invention, which is limited only by the appended claims.

Claims

CLAIMS1. Monitoring system (100) for monitoring the placement or removal of items (1) in a storage space (2), wherein the monitoring system comprises:- a communication assembly (6) configured for communication with at least one scanner (4) for scanning of item data;- a control unit (7) configured to be arranged in communication with the communication assembly (6), wherein the control unit (7) is configured to obtain a unique identification code for the at least one scanner (4), wherein the at least one scanner (4) comprises a radio based positioning unit (8) configured to transmit positioning signals comprising the unique identification code, and the monitoring system (100) comprises: wherein the communication assembly (6) is configured to receive the positioning signals from the radio based positioning unit (8), and- at least one LIDAR sensor (10), configured to be arranged in communication with the control unit (7), and configured to be arranged for registering images of the storage space (2), wherein the control unit (7) is configured- to determine a radio based tracking data (11) for the at least one scanner (4) based on the positioning signals received by the communication assembly (6);- to identify at least one person (12) in the registered images and to determine image based tracking data (13) for the at least one person (12) based on the registered images;- to determine image based tracking data (13) for the at least one scanner (4) by matching the radio based tracking data (11) with the image based tracking data (13);- to retrieve a set of scanned item data from the at least one scanner (4) via the communication assembly (6), corresponding to the items (1) which have been scanned with the at least one scanner (4); and- to determine whether the image based tracking data (13) matches the retrieved set of scanned item data.

2. Monitoring system (100) according to claim 1, wherein the communication assembly (6) comprises at least two radio based anchor units (9) configured to be arranged at predetermined positions in the storage space (2) in communication with the control unit (7).

3. The monitoring system according to claim 1 or 2, wherein the control unit (7) is configured- to receive an initiation message via the communication assembly,- to obtain a unique identification code for the scanner corresponding to the initiation message, and- to determine radio based tracking data (11) based only on positioning signals comprising a unique identification code corresponding to an initiation message.

4. The monitoring system according to claim 3, wherein the control unit (7) is configured to determine the unique identification code and to control the communication assembly (6) to send the unique identification code to the scanner.

5. The monitoring system according to any one of claims 1-4, wherein the radio based tracking data (11) and / or the image based tracking data (13) comprises positions as a function of time.

6. The monitoring system of claim 5, comprising a memory (14), wherein the determination of whether the image based tracking data (13) matches the retrieved set of item data, comprises the steps of:- retrieving from the memory (14) the storage positions of the items corresponding to the item data in the set of scanned item data,- identifying positions in the image based tracking data, from which positions the person has been within a predetermined distance for at least a predetermined period of time, as resting positions (15), and- determining whether each resting position (15) corresponds to a retrieved storage position of an item.

7. The monitoring system according to claim 6, wherein the image based tracking data (13) also comprises information on positions of the arms and / or limbs (16) of the persons.

8. The monitoring system according to claim 7, wherein, if it is determined that at least one resting position does not correspond to a retrieved storage position of an item, the control unit is configured to determine for said resting positions, whether a hand, has been within a predetermined distance from any storage position.

9. The monitoring system according to any one of the preceding claims, wherein the step of retrieving a set of scanned item data is performed when the control unit has received an end message.

10. The monitoring system according to any one of the preceding claims, wherein the communication assembly (6) comprises a scanner station (5) in which the scanner (4) is positioned before and after use, wherein the control unit is configured such that when it receives user information input by a user at the communication assembly (6), the control unit (7) controls the scanner station (5) to initiate one of the scanners (4), and stores the user information together with the unique identification code of the scanner (4).

11. A computer implemented method for monitoring the placement or removal of items (1) in a storage space (2), comprising the steps of:- obtaining a unique identification code of at least one scanner (4) for scanning of item data, wherein the at least one scanner (4) comprises a radio based positioning unit (8) configured to transmit a positioning signal comprising the unique identification code,- receiving positioning signals for the at least one positioning unit (8),- receiving from at least one LIDAR sensor (10) registered images of the storage space (2),- determining a radio based tracking data (11) for the at least one scanner (4) based on the positioning signals,- identifying at least one person (12) in the registered images and to determine image based tracking data (13) for the at least one person (12) based on the registered images,- determining image based tracking data (13) for the at least one scanner (4) by correlating the radio based tracking data (11) with the image based tracking data (13),- obtaining a set of scanned item data from the at least one scanner (4), corresponding to the items (1) which have been scanned with the at least one scanner (4), and- determining whether the image based tracking data (13) matches the retrieved set of scanned item data.

12. The computer implemented method of claim 11 , wherein the positioning signals for the at least one positioning unit (8) are received from at least two radio based anchor units (9), arranged at predetermined positions in the storage space (2).

13. The computer implemented method of claim 11 or 12, wherein the radio based tracking data (11) and / or the image based tracking data (13) comprises positions as a function of time.

14. The computer implemented method of claims 13, wherein the determination of whether the image based tracking data (13) matches the retrieved set of item data, comprises the steps of:- retrieving from a memory (14) the storage positions of the items corresponding to the item data in the set of scanned item data,- identifying in the image based tracking data positions, from which the person has been within a predetermined distance for at least a predetermined period of time, as resting positions, and- identifying whether each resting position corresponds to a retrieved storage position of an item.

15. The computer implemented method according to claim 14, wherein the image based tracking data (13) also comprises information on positions of the limbs and / or hands of the at least one person.

16. The computer implemented method according to claim 15, wherein, if it is determined that at least one resting position (15) does not correspond to a retrieved storage position of an item, the control unit is configured to determine for said resting positions using the image based tracking data, whether a hand has been within a predetermined distance from any storage position.

17. The computer implemented method according to any one of the preceding claims, wherein the step of retrieving a set of item data is performed after reception of an end signal.

18. A computer program product on which is stored a computer program comprising instructions, which when executed by a processor makes the processor (17) perform the method according to any one of claims 10-17.

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