System and method for improving safety of warehouse racks

Abstract

A warehouse rack safety system comprising a warehouse rack comprising a plurality of vertical beams and a plurality of horizontal beams, at least one sensor configured to measure one of a deformation of a horizontal beam of the plurality of horizontal beams, a load of a vertical beam of the plurality of vertical beams, a straightness of the vertical beam and a vibration of the rack, and at least one wireless transmitter configured to transmit measurement data from the at least one sensor.

Description

[0001] SYSTEM AND METHOD FOR IMPROVING SAFETY OF WAREHOUSE RACKS

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a system and a method for improving safety of warehouse racks and particularly detecting deformation of warehouse rack elements.

[0004] BACKGROUND OF THE INVENTION

[0005] Logistics centres and large warehouses typically apply large racks of shelves to store standard size pallets. To improve efficiency and productivity of the warehouses, they apply very high storage racks and condensed warehouse with optimized tolerances. Also, some level of automation is used to increase productivity. The safety risks have increased with increase of warehouse sizes, the height of the racks and the speed of operations in the warehouses. Damages in warehouse racks may cause problems for logistics operations and significant losses for the logistics operators.

[0006] Damages are typically caused by collisions of warehouse vehicles, shocks from colliding lifting forks of warehouse vehicles or rough handling of palettes. Damages may generate e.g. tearing in the beams via motion of the beam hangers of a shelf. Even when no visible damage can be seen the straightness of the rack may have deteriorated causing a decrease in load carrying capacity and a risk of rack failure.

[0007] BRIEF DESCRIPTION OF THE INVENTION

[0008] An objective of the present invention to provide a method and an apparatus for implementing the method so as to solve the above problems so as to alleviate the above disadvantages. The objects of the invention are achieved by a method and an arrangement which are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.

[0009] The invention is based on the idea monitoring the deformation of some elements or key elements of the warehouse racks, and collecting wirelessly the information of the rack status, shelf status, and status of some key components in the warehouse system. Detection of significant deformation can be configured to raise a warning and delivered inside the warehouse transported to another management system using different channels.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

[0012] Figure 1 illustrates schematically a warehouse rack;

[0013] Figure 2 illustrates schematically an embodiment of a warehouse safety system;

[0014] Figure 3 illustrates schematically an underpass structure of the warehouse safety system;

[0015] Figure 4 illustrates schematically another embodiment of the warehouse safety system;

[0016] Figure 5 illustrates a method for monitoring safety of a warehouse;

[0017] Figure 6 illustrates schematically rack control unit of the warehouse safety system;

[0018] Figure 7 illustrates schematically central control unit of the warehouse safety system;

[0019] Figure 8 illustrates schematically a system architecture of the warehouse safety system.

[0020] DETAILED DESCRIPTION OF THE INVENTION

[0021] Logistics centres and large warehouses apply typically large racks of shelves to store standard size pallets. To improve efficiency and productivity o the warehouses, they apply very high storage racks and condensed warehouse with optimized tolerances. A warehouse may host even tens of thousands of palettes. Also, some level of automation is used to increase productivity, but this may increase risks due to high concentration of vehicles and racks.

[0022] The racks may be even a hundred meters long. Any damages caused by human errors and errors in the automation system produce mechanical risks to the storage rack in the warehouses. To address these risk, several standards have been defined to ensure the safety of the palette racks such as EN-15635 regarding the application and maintenance of steel racking systems. Also, EN15512 is relevantin this context regarding structural design requirements applicable to all types of adjustable beam pallet rack systems fabricated from steel members. EN15620 specifies tolerances, deformations and clearances that pertain to the production, assembly and erection and performance under load of pallet racking and cantilever racking, EN15629 supplies guidelines for the technical specification to allow the design of racking and shelving in its various forms such as adjustable pallet racking (APR), crane serviced racking, drive-in racking (DIR), cantilever racking and shelving systems.

[0023] Referring to Figure 1, a warehouse rack 10 comprises a plurality of vertical beams 11 and a plurality of horizontal beams 12 interconnected to each forming a rack 10 of shelfs. The warehouse rack 10, may also comprise diagonal braces 13 between two of the vertical beams 11, which diagonal braces 13 are arranged perpendicularly with respect to the length on the rack 10 to provide a rigid structure to a pair of vertical beams 11. A warehouse may host a plurality of racks 10. Referring to Figure 2, according to an embodiment there is a warehouse safety system 100 comprising a plurality of sensors configured to measure deformation of the rack 10 and to transmit the measurement data with a wireless connection 39 to rack control unit 30. The rack control unit 30 may comprise a display 32 (see Figure 4) to display a warning and a status of the rack 10. The rack control unit 30 may receive sensor data from one or more racks. If the warehouse comprises a plurality of racks and a plurality of rack control unit 30, the warehouse safety system 100 may comprise a central control unit 40 to receive data from the rack control units 30 with wired connection 101 or a wireless connection 49. The central control unit 40 may comprise a display 42 to display a warning and a status of the rack.

[0024] Referring to figure 3, according to an embodiment there is a safety system 100 for warehouse rack 10 comprising a plurality of vertical beams 11 and a plurality of horizontal beams 12 interconnected to each forming a rack of shelfs. A typical warehouse or logistic centre applies multiples of such racks that may have a length from tens of meters even to a hundred meters. Referring to Figure 3, at least one sensor is configured to measure one of a deformation of a horizontal beam 12, 12a, 12b of the plurality of horizontal beams, a load of a vertical beam 11 of the plurality of vertical beams, a straightness of the vertical beam 11 and a vibration of the rack 10. A horizontal beam sensor 22 may be configured to monitor the deformation of the horizontal beam may be stretching, shrinking bending or warping. The deformation may be a result of overloading, an external shock, wearing of the rack material or a failure of a part in the rack 10 causing extra load or stress to other parts in the rack 10. Various sensors are known in the skill of the art such as a strain gauge, a piezoelectric sensor, an accelerometer, a torque sensor, and an optical sensor. Other types of sensor may also be used to measure load, strain or stress. At least one wireless transmitter configured to transmit measurement data from the at least one sensor. The wireless transmitter may use known wireless communication protocols such as Bluetooth (IEEE 802.15.1), ZigBee (IEEE 802.15.4), Wi-Fi (IEEE 802.11), Ultra-Wideband (UWB). The data throughput rate of the at least one sensor is not high, and the sensor needs to transmit data only with long intervals or it may be triggered to send data when a threshold in the deformation is exceeded. The first threshold is calibrated according to the object being measured. The at least one sensor may be configured to measure the load of a vertical beam 11 in the rack 10. The sensor measuring the load of the vertical beam 11 may be a pressure sensor or a strain gauge.

[0025] At least one sensor may be configured to measure a vibration of the rack 10. If the vibration of the rack 10 exceeds the first threshold, the warehouse management system 100 is configured output a warning signal by a central control unit 40 or a rack control unit 30. The central control unit 40 may be configured to store and accumulate the vibration data over a time period. In response to an aggregated vibration over a time period exceeds a second threshold, the warehouse management system 100 is configured the warning signal by the central control unit 40 or the rack control unit 30. In response to an increase in vibration exceeds a third threshold vibration over the time period, the warehouse management system 100 is configured to output the warning signal by the central control unit 40 or the rack control unit 30.

[0026] According to another embodiment, the at least one sensor may be configured to measure the deformation of the horizontal beam 12 in horizontal direction. Such deformation may be a result of an external shock such as a collision of a forklift or other warehouse vehicle. The deformation may be come up also in a different place than where the actual collision has happened as the deforming forces may peak in another part of the rack 10. In such a case, a damage may easily remain undetected without an active monitoring system. The detection of downward deformation of a horizontal beam 12 due to overloading or long-lasting stress is known in the art of the skill. However, external shocks may generate deformations in multiple directions of the horizontal beam. As the horizontal beams 12 are by default designed to carry loads and are by design strengthened in the vertical direction, deformations in horizontal directions are more critical. The horizontal beams 12b that are configured perpendicular against the length of the rack and are not typically directly used to place the palettes on them. A sensor 22b may be placed specifically on these horizontal beams 12a to detect the deformation of the rack 10.

[0027] According to another embodiment, the warehouse safety system 100 for warehouse rack 10, the warehouse rack 10 further comprises the diagonal brace 13 between two of the vertical beams 11. A strain sensor 23 is configured along the longitude of the diagonal brace 13 to measure a deformation of the diagonal brace 13. The sensor may be a strain gauge configured to detect a stretch or a collapse of the diagonal brace 13. The strain gauge may be configured to detect a collapse to any perpendicular direction with respect to the length of the diagonal brace 13. Even a slight deformation in the diagonal brace 13 may be critical for the safety of the rack 10 because a significant deformation of the rack 10 may first emerge in the diagonal brace 13 before it is detected in any of the horizontal or any of the vertical beams 11.

[0028] According to another embodiment, the warehouse safety system 100 further comprises a collision protection guard 14 for each vertical beam. A collision detection sensor 24 is configured to measure a displacement of the collision protection guard 14 of a vertical beam 11 of the plurality of vertical beams. The collision detection sensor 24 may be a strain gauge, an accelerometer or capacitive or inductive sensor. Other types of sensors may also be used. If the collision protective guard 14 has moved more than a distance of threshold, the warehouse safety system 100 may output a warning signal. The threshold may be set so that a safety marginal is maintained between the collision protection guard 14 and a vertical beam 11. In this case, the safety margin can be considered as part of the rack system, of which deformation is monitored by the warehouse safety system 100. The collision detection sensor 24 comprising passive sensing element may be configured to be in a sleep mode and to trigger a warning signal in the warehouse safety system 100 once the collision detection sensor 24 measures a deformation exceeding the first threshold. An end-of-the-rack collision protection guard 15 may be configured at at least one end of the rack 10. A collision detection sensor 25 may be configured in an end of the end-of-the-rack collision protection guard 15 to monitor a corner of the rack 10. The cornering vertical beams are more exposed to collision risks and also more critical for the safety of the rack 10. The protection guards 14 may be installed separately after the actual system or additional protection guards 15 may be added later to the system to cover more locations such as vertical beams 11. The threshold for detecting a collision may be readjusted after more protection guards 14 have been added. A new value for threshold may be determined with respect to the geometry of the rack 10 and the plurality of pro- ception guards 14.

[0029] According to another embodiment, the warehouse safety system 100, the at least one sensor is configured to measure a deformation of a horizontal beam 12a arranged above an underpass 16 in the rack 10. A long rack typically comprises one or more underpasses for the warehouse vehicles to move from an aisle to another aisle without the need to go around the end of the rack 10. The beams around the underpass 16 are at risk to more frequent collisions. Especially, the horizontal beams 12a above the underpass 16 are at higher risk. These horizontal beams 12a may be equipped with protective shields 17 or warning labels. The sensor may be configured to detect the horizontal movement of the horizontal beam 12a that may be a result of the collision. The collision typically causes a deformation in horizontal direction. The sensor may be an accelerometer or a strain gauge. Other types of sensor may also be used.

[0030] According to another embodiment, the warehouse safety system 100 further comprises one of an optical and a radio transmitter, wherein the one of an optical and a radio transmitter is configured to indicate the open height 16b of the underpass 16 in the rack 10. Anticollision systems in warehouse vehicles are known in the skill of the art, typically based on LiDAR. The optical transmitter is configured to transmit a guided light beam along the open height 16b of the underpass 16 in both directions of the underpass 16. The transmitter may also be an radio transmitter configured to transmit a beamformed radio signal or periodic beamformed pulses. The optical signal or radio signal or pluses may be used in warehouse vehicles to raise an alert to avoid collision. A proximity sensor may be placed in horizontal beam 12a comprising one of an optical, an inductive, a capacitive, and a magnetic sensing element to detect the proximity of a vehicle. The sensor data may be transmitted to the rack control unit 30 to raise an alarm. The proximity sensor may also trigger an audible or an visual alarm by an alarm device configured in the proximity of the horizontal beam 12a. The alarm may be delivered via a display, a light, or via wireless network to a user, locally on-site or off-site.

[0031] Referring to Figure 7, the rack control unit 30 is configured to receive the measurement data from the at least one wireless transmitter and in response to the measurement exceeding a first threshold, the central control unit 40 is configured to output a warning signal. The rack control unit 30 may comprise a processor 32, a memory 33, and a wireless transceiver 38 to receive data from the at least one sensor. The rack control unit 30 may comprise at least one of means for outputting an audible warning signal such as a loudspeaker 37, a display 32 to output a warning message on the display 32. The wireless transceiver 38 may also be configured to transmit information about a rack damage to the central control unit 40.

[0032] Referring to Figure 8, according to another embodiment, the warehouse safety system 100 comprises a plurality of rack control units 30, wherein the central control unit 40 is configured to receive the measurement data from the plurality of rack control units 30 and in response to any or rack control units 30 transmitting information of a rack failure the central control unit 40 is configured to output a warning signal. The central control unit 40 may comprise a processor 41, a memory 51, and a wireless transceiver 48 to receive data from the at least one sensor. The central control unit 40 may comprise at least one of means for outputting an audible warning signal such as a loudspeaker 47, a display 42 to output a warning message on the display 42. The central control unit 40 may be configured store measurement data in a measurement database 62 in storage 60 for log-term analysis in at least one of rack status, increase in deformation a beam, and accumulated vibration.

[0033] According to another embodiment, the rack control unit 30 may be configured to receive measurement data from a first and a second sensor in the rack 10. The first sensor and the second sensor may be configured to measure the deformation of a horizontal beam 12 of the plurality of horizontal beams, the load of a vertical beam 11 of the plurality of vertical beams, and the vibration of the rack 10. If the sum of the two measurements is exceeding a second threshold, the central control unit 40 is configured to output the warning signal. The central control unit 40 may be also configured to determine a correlation between the measurements of the first sensor and the second sensor and in response to the correlation exceeding a correlation threshold outputting a warning signal.

[0034] According to another embodiment, the warehouse safety system 100 further comprises comprising in an end of the rack 10 a display 32 configured to receive data from the rack control unit 30 and to display at least one of the measurement data and an indication of an exceeding of the first threshold. The central control unit 40 may also be placed at the end of the rack 10 and comprise the display 42.

[0035] The technology for all sensors is preferably as similar as possible, so that their technical differences may be covered on a software layer e.g., to control the alarms to the rack control unit 30. For example, WiFi technology may be used for wireless communication between a rack control unit 30 and the sensors in the rack 10. Ethernet cabling may be used from the rack control unit 30 towards the central control unit 40 for operational reliability, however, also wireless communication may also be used the rack control unit 30 towards the central control unit 40 depending on the capacity of battery operation, i.e., the longest possible service life.

[0036] The sensor devices and wireless rack control units 30 would automatically report the status of the batteries, and the software should optimize the replacement of batteries so that the system assembles the next cycle e.g., batteries to be replaced during a planned period of service time. One rack may comprise one IP network, in which case the one IP network would host 255 sensors.

[0037] The collision protection guard 14 may be a rubber bag hung on the top edge of the protective shield 17, which may be configured to react to the increase in the bag's pressure during a collision with a pressure sensor, where the bag may be configured to have some pre-pressure in the bag (of the order of 20...50 kPa), and the rubber bag may also equipped with an overpressure valve (e.g. 100 kPa) so that the bag itself could not cause damage to the vertical bar.

[0038] The load sensor 21 for the vertical beam 11 would be a strain gauge sensor connected to a simple Wheatstone bridge. This is because the deformation of the vertical beam 11 due to excessive load may be very small in dimension. A quarter bridge may also be used because temperature compensation is not necessary in the warehouse conditions, similarly the compensation of the connection wires of the strain gauge is optional because the wires are short. The load reference parameters may be programmed for the vertical beams 11 of different manufacturers according to their characteristics.

[0039] The sensors monitoring the deformation of the horizontal beams 12 and the diagonal braces 13 may be configured to monitor deformation in two directions. The two-directions sensor capability may be configured in a sensor unit to be placed on a horizontal beam 12 or in a diagonal brace 13.

[0040] The vibration sensor for the rack 10 may be a three-axis acceleration sensor. The positioning of the vibration sensor is case-specific, e.g., general monitoring of the rack 10 vs. critical points of the rack 10 such as underpasses 16 and the ends of the racks 10 where there is the most lateral traffic. On the other hand, sensors may be placed in the highest points of the rack 10 to monitor the vibration more precisely due to the severity of possible damage.

[0041] The straightness sensors of the rack 10 may be placed on the back surface of the uppermost horizontal beam 12 due to the least possible distractions. The straightness sensor may comprise a transmitting laser configured on the lowest horizontal beam at one end of the rack 10 and an optical receiver configured at the second end of the rack 10. The transmitting laser is configured to point to the optical receiver during installation. The horizontal beams 12 between the first end and the second end of the rack 10 may comprise a hole through which the laser is configured to pass. Any sag in the rack 10 causes a cutoff of the laser beam, in which case the sensor transmits a signal of a detected cutoff, which is configured to raise an alarm by the warehouse management system 100. Alternatively, the laser transmitter may be configured as a distance meter with a passive light detecting object as a receiver of the laser beam. The distance may be measured e.g., once an hour, and a change in the measurement result against a preset value causes an alarm. In the use of the laser transmitter, the battery lifetime may be optimized by configuring a measurement interval long, e.g., one hour, as the objective is to detect accumulating changes soon.

[0042] The optimization of battery usage may be considered in the design of all sensors, so that a sleep mode of the sensors is maximized, and measurements are performed at a long-time interval, since it is not necessary to measure every moment. An exception to this may be the monitoring of underpasses 16, which may be constantly monitored. The underpasses 16 may be monitored either optically or with the help of a proximity sensor / sensors, or a combination of these in order to identify all types of loads that threaten to underpass 16.

[0043] The processing of the measurement data starts with the sensors i.e., in the operating environment of the physical sensor, which typically may cause noisy signals from all types on sensors, and where noise cancellation may be applied already at the sensor. Limit values may be programmed according to the type of sensor and the placement of the sensor. The measurement data maybe sent to the rack control unit 30, where a time stamp may be associated with the measurements event. A location information of the sensor, and the measurement data of the observed event may be transferred central control unit 40, wherein the central control unit 40 may be presented in a user interface for further classification by a user. The event may be classified according to severity and mandatory monitoring information can be sent to the user devices of operators.

[0044] According to an embodiment there is a method 200 for generating a warning signal for a damage of a warehouse rack 10 comprising

[0045] • Receiving 201 a deformation measurement from at least one sensor configured to at least one of a beam of a plurality of vertical beams 11 and a plurality of horizontal beams 12, 12a 12b, wherein the horizontal beams 12, 12a, 12b and vertical beams 11 are interconnected to a rack 10 of shelfs, wherein the at least one sensor is configured to measure one of a deformation of a horizontal beam 12, 12a, 12b of the plurality of horizontal beams, a load of a vertical beam 11 of the plurality of vertical beams, a straightness of the vertical beam 11 and a vibration of the rack 10. The deformation of the horizontal beam 12, 12a, 12b may be stretching, shrinking bending or warping. The deformation may be a result of overloading, an external shock, wearing of the rack material or a damage of a part in the rack 10 causing extra load or stress to other parts in the rack 10. Various sensors are known in the skill of the art such as a strain gauge, a piezoelectric sensor, an accelerometer, a torque sensor, and an optical sensor. Other types of sensor may also be used to measure load, strain or stress.

[0046] • Transmitting 202 the deformation measurement data from the least one sensor by a wireless transceiver. The wireless transmitter may use known wireless communication protocols, mentioned above. The data throughput rate of the at least one sensor is not high, and the sensor needs to transmit data only with long intervals or it may be triggered to send data when a threshold in the deformation is exceeded.

[0047] • Receiving 203 by one of a rack control unit 30 the deformation measurement data and in response 204 to the deformation measurement exceeding the first threshold, outputting 205 a warning signal.

[0048] According to another embodiment of the method, the method further comprises receiving by the rack control unit 30 the deformation measurement data from a first and a second sensor in the rack 10. If the sum of the two measurements is exceeding a second threshold, the warning signal is outputted by the rack control unit 30 or the central control unit 40. The measurement data may be the deformation of a horizontal beam 12, 12a, 12b of the plurality of horizontal beams, the load of a vertical beam 11 of the plurality of vertical beams, and the vibration of the rack 10. A correlation between the measurements of the first sensor and the second sensor may be determined by the central control unit 40 and in response to the correlation exceeding a correlation threshold a warning signal may be outputted.

[0049] According to another embodiment of the method, the method further comprises receiving data from the central control 40 and displaying in a display 32 at an end of the rack 10 at least one of the measurement data and an indication of an exceeding of the first threshold. The displaying of the at least one of the measurement data and an indication of an exceeding of the first threshold may also be performed in a display 32 comprised the rack control unit 30 placed at the end of the rack 10.

[0050] According to another embodiment of the method, the method further comprises transmitting one of an optical and a radio signal, wherein the one of an optical and a radio signal is configured to indicate the open height 16b of the underpass 16 in the rack 10. The method comprises transmitting a guided light beam along the open height 16b of the underpass 16 in both directions of the underpass 16 by an optical transmitter. The method may also comprise transmitting a beam- formed radio signal or periodic beamformed pulses. The optical signal or radio signal or pluses may be used in warehouse vehicles to raise an alert to avoid collision.

[0051] It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

CLAIMS1. A warehouse rack safety system (100) comprising: a warehouse rack (10) comprising a plurality of vertical beams (11) and a plurality of horizontal beams (12, 12a, 12b); at least a first sensor configured to measure one of a load of a vertical beam (11) of a plurality of vertical beams; and at least one wireless transmitter configured to transmit measurement data from the at least one sensor to a rack control unit (30), wherein the rack control unit (30) is configured to display a load measurement and in response to the measurement exceeding a first threshold, the central control unit is configured to output a warning signal.

2. A warehouse rack safety system (100) according to claim 1 wherein a second sensor is configured to measure a straightness of the rack (10); a wireless transmitter configured to transmit measurement data from the wireless sensor to the rack control unit (30), wherein the rack control unit (30) is configured to display measurement results and in response to a sum of the first and second sensor measurements exceeding a second threshold or a correlation between the first and second sensor measurements exceeding a correlation threshold, the rack control unit (30) is configured to output a warning signal.

3. A warehouse rack safety system (100) according to any preceding claim wherein the warehouse rack (10) further comprises a collision protection guard (14) for each vertical beam, and a sensor is configured to measure a displacement of the collision protection guard (14) of a vertical beam of the plurality of vertical beams (11).

4. A warehouse rack safety system (100) according to any preceding claim wherein the at least one sensor is configured to measure a deformation of a horizontal beam (12a) arranged above an underpass (16) in the rack (10).

5. A warehouse rack safety system (100) according to claim 4 further comprising one of an optical and a radio transmitter, wherein the one of an optical and a radio transmitter is configured to indicate the open height (16b) of the underpass (16) in the rack (10).

6. A warehouse rack safety system (100) according to any preceding claims, wherein a central control unit (40) is configured to store measurement data received from the rack control unit (30) and in response to an increase a trend of the vibration measurement exceeds a third threshold over a time period, the system (100) is configured to output the warning signal by the central control unit (40) or the rack control unit (30).

7. A method for detecting a fault in a warehouse rack (10) comprising a plurality of vertical beams (11) and a plurality of horizontal beams (12), the method comprising: measuring one of a load of a vertical beam (11) of the plurality of vertical beams transmitting wirelessly a first measurement data from the sensor; and receiving by a rack control unit (30) the first measurement data and in response to the measurement exceeding the first threshold, out- putting a warning signal.

8. A method according to claim 7, the method further comprising measuring a straightness of the rack (10); transmitting wirelessly a second measurement data from the wireless sensor to a central control unit; and receiving by a rack control unit (30) the second measurement data; and in response to a sum of the first and second sensor measurements exceeding a second threshold or a correlation between the first and second sensor measurements exceeding a correlation threshold, the rack control unit (30) is configured to output a warning signal.

9. A method according to any preceding claim 7-8 further comprising a displaying in a display (32) at an end of the rack (10) at least one of the measurement data and an indication of an exceeding of the first threshold.

10. A method according to any preceding claim 7-9 further comprising transmitting one of an optical and a radio signal, wherein the one of an optical and a radio signal is configured to indicate the open height (16b) of the underpass (16) in the rack (10).

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