GB2593536A

GB2593536A - Measuring the flow of parts in an assembly line

Info

Publication number: GB2593536A
Application number: GB2004518.3A
Authority: GB
Inventors: Cooper Daniel; Cartwright Robert; Tiwari Ashutosh; Song Boyang; Tiwari Divya; Hutabarat Windo
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2021-09-29
Anticipated expiration: 2040-03-27
Also published as: GB2593536B; GB202004518D0

Abstract

Parts are provided in bins 14 that move, assisted by gravity, along at least one inclined lane 10 to an assembly line 12. A load is measured at the front of a queue of multiple bins in the inclined plane, providing an indication of the number of bins in the queue and the amount of parts in the frontmost bin. In an aspect, a supply management apparatus comprises multiple inclined planes, each associated with a single type of part and provided with a load cell 16. One or more processing units 18, 24 provide information on the amount, rate of supply and rate of depletion of parts of a certain type in one or more lanes. In an aspect, a supply management function is added to an existing assembly line by adding a load cell to each of multiple inclined lanes, and arranging one or more processing units to manage the supply of parts to the assembly line.

Description

MEASURING THE FLOW OF PARTS IN AN ASSEMBLY LINE BACKGROUND OF THE INVENTION

100011 The present disclosure relates to measuring the flow of parts in an assembly line. More particularly, but not exclusively, this invention concerns a method of measuring the flow of such parts and a supply management apparatus for use on an assembly line in an assembly line, for example within an industrial setting.

100021 An assembly line process may be used to manufacture a product, such as a vehicle, a vehicle component or a vehicle sub-assembly. The product is progressively assembled as it travels along the assembly line. Assembly lines of the prior art may include one or more lanes that feed parts to the assembly line. A bin moves along the lane to a location on the assembly line at which one or more parts in the bin are used in assembling the product being manufactured. For example, a manual operator may take parts from the bin as and when required for use in the assembly process. A queue of bins of parts may form at the lane. When a bin at the front of the queue is empty of parts, the operator may manually remove the bin from the lane, allowing the next bin in the queue to move to the front. Some lanes are inclined such that movement of a bin to the front of the queue is assisted. The lane may for example comprise rollers over which the bins move, when the bins move forwards in the queue.

100031 It would be beneficial, for the purpose of efficiently managing the flow of parts in the assembly line and/or for the purpose of reducing the risk of running out of parts at a lane that feeds the assembly line, to measure and preferably control, the flow of parts in each lane For example, it would be beneficial to know the amount of parts on a lane-by-lane basis, and preferably how that varies over time. Such information could then be used to manage and control the flow of parts to the assembly line. It would be preferred if the person acting as the manual operator associated with the lane did not need to manually input the number of parts in the lane or take extra action to indicate when one or more parts are removed from the bin(s) in the feed lane.

[0004] There are various proposals in the prior art for assisting with managing and controlling the flow of parts to an assembly line.

100051 US20170327312 discloses a dynamic storage rack unit which uses sensors to monitor how many material containers are present within a storage rack compartment, the sensors being spaced apart along the length of the storage rack compartment by a distance corresponding to the length of the container. The storage rack compartments are sloped One sensor is required for each material container.

100061 US20170147966 discloses an inventory monitoring system including shelf inventory sensor devices that each include cameras and distance sensors arranged to monitor shelf occupancy, for use for example in the retail industry. Similarly, U520170228686 discloses a set of "smart shelves" including strain sensors, photo detectors, microphones, and the like which together form a sensor mesh arrangement which can generate a signal representative of a product count for a given product to be sold from the shelf, again in the retail industry. 100071 JP2014091608 concerns a system to assist the picking of articles from one or more supply containers to be collected in a collection container at a picking station. The system uses an imaging device (camera) to identify the type and number of articles being collected. 100081 US20110153466 discloses an inventory management system and method using bins which carry inventory and which each comprise a load cell, which measures the weight of the inventory in each bin. The information from the load cells may be collated via a communications network.

100091 US 20190073627 discloses a system and method for monitoring stocked shelves, including a shelf monitor which comprises an array of light sensors facing the stock.

100101 Those systems described above that require detection of bins using multiple sensors or cameras for detecting bins on an individual basis would not be easily implemented on an assembly line that has not got suitable infrastructure already in place. For the purpose of retro-fitting a supply management apparatus on an existing assembly line having no such sensors or cameras already, it would be preferable for the retro-fit kit to have fewer sensors, cameras or the like, so as to keep the retro-fitting process simple and fast.

100111 The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method of measuring the flow of parts in an assembly line. Alternatively or additionally, the present invention seeks to provide an improved supply management apparatus for use on an assembly line. Alternatively or additionally, the present invention seeks to provide a practical -3 -way in which to retro-fit a supply management apparatus for use on an existing assembly line.

SUMMARY OF THE INVENTION

[0012] The present invention provides according to an aspect of the invention a method of measuring the flow of parts in an assembly line. The assembly line includes at least one inclined lane (e.g. a flow rack) that feeds parts to the assembly line. Parts are provided via bins that move along the lane towards the assembly line. A bin may, for example, comprise a box in which the parts are carried. The lane is inclined so that movement of the bins along the lane is assisted at least in part by gravity. When multiple bins are received in a lane, the bins form a queue of bins in that lane. A lane may at certain times have only one bin in the queue at the lane. At other times there may be three or more bins in the queue in a lane. The method includes measuring a load at the front of the queue of bins in a lane, and using the load so measured to provide an indication of one, or preferably both of, (i) the number of bins in the queue in the lane and (ii) the amount of parts in the bin at the front of the queue. In embodiments of the invention, there may thus be a method of providing real-time information on both the number of bins in the queue and the number of parts in the bin at the front of the queue, in each gravity feed lane within an assembly line, thus enabling better stock control -but without requiring complicated sensor arrangements and/or without requiring at least one sensor per bin to be detected. The provision of more accurate/precise information in real-time allows for finer control of the flow of parts, for example.

[0013] It will be appreciated that the assembly line may comprise multiple streams of parts being assembled in series and/or in parallel. The parts are assembled to form a product, which may be a finished product, or may be a component for use in a finished product, a subassembly, or the like.

[0014] The load at the front of the queue of bins in a lane may be measured using a conventional load cell. The load cell may generate an analogue signal in response to the load. An analogue to digital signal converter may be used to convert such an analogue signal to a digital one. A processing unit may be provided and arranged to receive a signal representative of the load so measured, for example from such a load cell. A processing unit (for example the same processing unit) may be arranged to process a signal representative of -4 -the load at the front of the queue in order to produce an output signal that includes both information concerning the number of bins in the queue in the lane, and the amount of parts in the bin at the front of the queue. Such an output signal may be in the form of digital data. A processing unit may be arranged to monitor the load so measured over time. The monitoring of how the load changes can enable the processing unit to ascertain when a bin is added, when a part is removed from the bin at the front of the queue, and/or when an empty bin is removed from the front of the queue. The processing unit and/or the measuring of the load (and how that measured load is then used) may need to be programmed and/or calibrated in view of one or more of the mass of a full bin, the mass of an empty bin, the mass of a single part, the number or mass of parts that are provided in a full bin, and how those masses affect the load measured at the front of the queue, in the particular set-up of the embodiment concerned. The method may include one or more calibration steps accordingly.

[0015] A processing unit may be arranged to deem an increase in the load so measured as indicative of the number of bins in the lane increasing by one, if (and preferably only if) certain predefined criteria are met. For example, if the load increases by a certain amount (within a margin of error) within a certain period of time (for example between successive measurements of the load being taken, assuming that such measurements are taken regularly, say at least every second), such a rapid increase in load can be safely assumed to result from a new bin, full of parts, arriving at the back of the queue.

100161 A processing unit may be arranged to deem a reduction in the load so measured as indicative of the number of parts in the front bin decreasing by one, if (and preferably only if) certain predefined criteria are met. For example, if the load decreases by a certain amount (for example, an amount that is within a predetermined range corresponding to the likely minimum and maximum loads to arise from the mass of a single part) within a certain period of time, such a step-wise decrease in load can be safely assumed to result from a single part being removed from the bin at the front of the queue. In the case where many parts (for example small parts) are provided in a bin and/or the parts are such that an operator is likely to take more than one part at a time from the bin at the front of the queue, the exact number of parts in the front bin may not be known with precision. Instead, the method may be performed to provide an indication (for example as an estimation) of the amount of parts in -5 -the bin at the front of the queue, for example expressed as a fraction or percentage of the amount when the bin is deemed to be full.

100171 It may be that the processing unit is arranged to store historical data (for example relating to the loads measured previously and/or the previously ascertained number of bins and/or the previously ascertained amount of parts in the bin at the front of the queue) and use such historical data to ascertain the present number of bins in the queue in the lane and/or the amount of parts (e.g. the number of parts) in the bin at the front of the queue. This may be achieved by for example making various assumptions on the way in which the state of the system being measured may change over time. For example, it may be that it is assumed that only bins full of parts are added, one at a time, at the back of the queue. It may be assumed that a full bin always has the same amount / number of parts in it. It may then be assumed that an increase in the measured load above a given magnitude must be as a result of the number of full bins in the queue increasing by one. It may also be assumed that a bin is only removed from the front of the queue. It may then be assumed that the measured load temporarily dropping from a first load to zero and then rising again to a second load, being lower than the first load, corresponds to when a bin (for example an empty bin) is removed from the front of the queue. It may also be assumed that parts are only ever removed from the front bin. It may also be assumed that parts are only ever removed one at a time from the front bin. It may then be assumed that the measured load reducing by a certain amount corresponds to when a single part is removed from the bin at the front of the queue. In cases where it is not appropriate to assume that parts are only removed one at a time from the front bin, the magnitude of the reduction in load may be used to ascertain the amount (for example, number) of parts removed from the front bin (and therefore the amount of parts remaining in the front bin). The processing unit may store in memory the times at which parts are removed from the front bin and/or when a full bin is added at the rear of the queue. The processing unit may keep track of how the amount/number of parts reduces over time. For example, the processing unit may store a series of data showing how the amount/number of parts reduces over time.

100181 It may be that the load measured at the front of the queue includes a component of the weight of each bin in the queue. For example, the load may be measured in a direction that includes a component of the weight of each bin in the queue. Such a direction may be angled -6 -closer to the horizontal than to the vertical. The direction that the load is measured in may be aligned with the direction of incline of the lane. By measuring the load at the front of the queue in such a way that all bins in the queue contribute to the load so measured, it is possible in embodiments of the invention to have a single load measurement (varying over time) from which all information on the number of the bins and the amount of parts in the front bin, can be ascertained. This reduces the number of sensors needed (not necessarily one per bin in the queue) and makes it easier to retrofit the one or more sensors needed for implementing the method in an existing assembly line having one or more gravity-feed lanes. 100191 The load measured may be the force of contact between the front of the bin at the front of the queue and a load cell. There may be intervening structure, between the front of the bin and the load cell, for example a metal plate, spring, cushion and/or other elements, without necessarily impairing the method.

[0020] The indication of the number of bins and/or of the amount of parts in the front bin may comprise a non-visual indication. For example, the indication may be provided by means of data and/or a signal that is processed by other elements or processors. Additionally or alternatively, a visual indication may be provided. The visual indication may be provided on a display unit, for example showing both a representation of the number of bins in the queue in the lane and a representation of the amount of parts in the bin at the front of the queue. There may be a display unit provided for each lane that feeds parts to the assembly line. A single display unit may show information on the number of bins and/or the amount of parts in the front bin in respect of multiple lanes.

[0021] The method of the invention may be performed in respect of multiple lanes. Information on the rate of usage of parts (e.g. the rate at which parts are removed from the front bin) may be collated and processed by a computer system. The computer system may be associated with the assembly line and/or be a central computer system. Alternatively or additionally, information on the number of bins in each lane may be collated and processed by a computer system (for example the same computer system). Alternatively or additionally, information on the amount of parts in the bin at the front of the queue of each lane may be collated and processed by a computer system (for example the same computer system). Alternatively or additionally, information on the amount of parts in all the bins in the queue of each lane may be collated and processed by a computer system (for example the same computer system).

100221 The computer system may be, or form part of, a manufacturing resource planning system.

100231 There may be a step of determining data relating to the rate of consumption of parts (for example, ascertaining a consumption pattern) in a lane. Such data can then be used in managing the rate of supply of parts and/or bins of parts to that lane, for example thus reducing the risk of there being an inadequate supply of parts to the assembly line from that lane.

10024] The method of the invention has particular application in relation to an assembly line for manufacturing a vehicle, or a part or component for a vehicle. The product being made on the assembly line may be an aircraft component or sub-assembly.

10025] The weight of a full bin may be greater than 5Kg, possibly greater than 10Kg. The weight of a full bin may be less than 501Kg, and preferably less than 301Kg. The weight of an empty bin may be greater than 100g and optionally greater than 1Kg. All the parts in a full bin may be of the same type. All bins in a queue in a single lane may all contain parts of the same type. Each part may have a mass of greater than 100g, optionally greater than 500g, and possibly greater than 2Kg. The invention may also have application in relation to parts such as washers, which may each by very light, for example weighing less than lg each. 100261 According to the invention there is also provided a supply management apparatus for use on an assembly line. The supply management apparatus may for example be configured to perform the method of the invention, as described or claimed herein. The supply management apparatus may be configured for use on an assembly line which utilises multiple inclined lanes that feed parts to the assembly line, each lane being associated with a single type of part, the parts being provided via bins, each lane being configured to accommodate multiple bins in a queue of bins and to allow parts to be removed for use in the assembly line from the bin at the front of the queue, each bin carrying multiple parts to the assembly line, and each lane being configured to be inclined so as to assist movement of the bins towards the front of the queue. The supply management apparatus may comprise for each inclined lane, a load cell for measuring a load at the front of the queue of each lane. The supply management apparatus may include one or more processing units for receiving a signal from -8 -each load cell and from such a signal ascertaining information for use in the management of supply of parts within/to the assembly line. The one or more processing units may be configured to ascertain for each lane the number of bins in the queue in the lane. The one or more processing units may be configured to ascertain for each lane the amount of parts in the bin at the front of the queue. The one or more processing units may be configured to produce output data, for example for use in the management of supply of parts within/to the assembly line. The output data may comprise information on the amount of parts of a certain type in one or more lanes. The output data may comprise information on the rate of supply of parts of a certain type to one or more lanes. The output data may comprise information on the rate of depletion of parts of a certain type from one or more lanes.

[0027] It may be that a processing unit provided for the purpose of calculating, for a lane, the number of bins in the queue in the lane and the amount of parts in the bin at the front of the queue, is different from the processing unit provided for the purpose of outputting data providing information, in relation to that same lane, on one or more of (a) the amount of parts of a certain type in the lane (b) the rate of supply of parts of a certain type to the lane and (c) the rate of depletion of parts of a certain type from the lane. It may be that a single processing unit performs both such purposes.

[0028] The supply management apparatus may include one or more visual display units arranged to provide a visual indication, for each lane, of the number of bins in the queue in the lane and/or the amount of parts in the bin at the front of the queue.

[0029] According to the invention there is also provided a manufacturing resource planning system, for example implemented on a computer, which is arranged to receive data from the one or more processing units mentioned above. Such a manufacturing resource planning system may be configured to output information which is then used to manage the flow of parts in an assembly line. It will be appreciated that there may be intermediate steps / processors for processing of and/or collating of data in order to achieve this.

[0030] According to the invention there is also provided a processing unit for use in the apparatus and/or method as described or claimed herein.

[0031] According to the invention there is also provided a method of adding (e.g, retrofitting) a supply management function to an existing assembly line, of the type referred to herein. Such a method may include adding a load cell to the front of each inclined lane, each -9 -load cell being arranged to measure a load at the front of the queue of the lane, and to send a signal to one or more processing units configured to receive such signal(s). Such a method may include arranging one or more processing units to receive such load signal(s). The processing unit(s) may be arranged to calculate for each lane the number of bins in the queue in the lane, and the amount of parts in the bin at the front of the queue, using such load signal(s). The processing unit(s) may be arranged to output data that can then be used to manage the supply of parts to the assembly line. A kit of parts for use in the method is also provided.

100321 It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa.

DESCRIPTION OF THE DRAWINGS

[0033] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: Figure 1 shows a supply management apparatus according to an embodiment of the invention being used on an assembly line; Figure 2 shows a part of the supply management apparatus of Figure 1 in relation to a lane that feeds the assembly line, and Figures 3 to 6 illustrate a method of measuring the flow of parts in an assembly line according to a second embodiment of the invention.

DETAILED DESCRIPTION

[0034] Figure 1 shows three inclined (gravity feed) lanes 10 (or flow racks) feeding an assembly line represented by the long arrow 12 in Figure 1. The assembly line forms part of a manufacturing facility for making aircraft parts. Each lane 10 carries boxes 14 of parts to the assembly line, each line delivering parts of a single type to the assembly line. The lane W at -10 -the top of Figure 1 has a queue of three boxes 14. A manual operator removes parts from the box 14 at the front of the queue as and when required in the assembly line process. The lane 10 has rollers (not shown separately) which support the weight of the boxes 14, and which also allow the boxes 14 to move down the lane 10 under the action of gravity. The supply of parts in boxes 14 to the assembly line is controlled by a supply management apparatus.

[0035] The supply management apparatus comprises, for each inclined lane 10, a load cell 16 for measuring a load at the front of the queue of each lane. The load measured by the cell 16 is that which results from the weight of the queue of boxes 14 pushing, as a result of gravity, onto the load cell 16 at the front of the queue of boxes 14. The load measured is the force which results from the queue of boxes 14 pushing onto the sensor as resolved in the direction of the slope of the lane 10 (direction D shown in Figure 1). This force is the component of the weight of the boxes 14 due to gravity in this direction Ong sin ID) less the friction force (p mg cos 0), where in is the mass of the boxes, g is 9.8ms-2, 0 is the angle of inclination relative to the horizontal, and,/t is the effective friction coefficient.

[0036] The analogue signal from the load cell 16 is converted by an analogue to digital converter (not shown separately) and then received by a local processing unit 18. The local processing unit 18 and its load cell 16 are calibrated and set up to be able to recognise by monitoring the change in load measured when a new full box 14 of parts is added and when a given amount of parts is removed from the box 14 at the front of the queue. The local processing unit 18 and its load cell 16 may also be calibrated and set up to be able to recognise by monitoring the change in load measured when an empty box 14 is removed from the front of the queue. It will be appreciated that the load may reduce to zero at such a time, until the box 14 immediately behind the one that was removed reaches and makes contact with the load cell 16. From the load measured, the processing unit 18 is able to infer how many boxes 14 are present on the lane, and how full the box 14 at the front of the queue is. This information may, as explained in further detail below, be deduced by a combination of the total load measured and the change of load measured. It may be assumed that each box 14 added to the lane 10 is filled with the same number / amount of parts each time. Historical measurements of the sensed load are recorded in memory. The computational logic contained within the processing unit 18, in effect, transforms the historical forces so recorded into real-time stock quantities. The load is measured about once every second.

100371 Each local processing unit 18 associated with each lane 10 causes the number of boxes 14 present in the lane 10 and the amount of parts in the front box 14 to be displayed on a local display unit 20. Such information is also sent by each local processing unit 18 across a network 22 to a central computer 24. The central computer 24 is programmed to use such information to provide real-time measuring and managing of stock quantities in the assembly line including those in the inclined lanes 10. This may then allow shop-floor supply logistics to be improved by reducing waiting time. The central computer 24 is configured to display an electronic dashboard (not shown separately in the Figures) that gives the user the ability to audit the entire assembly line in seconds, thus significantly reducing the risk of the parts supplied via any given lane 10 reaching zero and disruption being caused. The central computer 24 is also programmed to recognise trends and patterns in the rates of consumption of various parts. Such information can then be used to plan/align replenishment times more accurately/efficiently, thus reducing the stock levels required overall. The present embodiment is able to measure accurately (within acceptable margins of error that may arise from time to time) the amount of parts in the lanes 10 feeding the assembly line, not merely the number of boxes present. Knowing the number of parts within a box, allows greater accuracy and precision than is possible with stock counting systems that merely detect the number of boxes in the assembly line feeding lanes.

100381 Figure 2 shows the upper lane 10 from Figure 1, there being six parts in each full box 14 and four parts in the box 14 at the front of the queue. The load cell 16 is shown measuring the component of the weight of the three boxes 14 as resolved in direction D. The local processing unit 18 is shown as sending data to both the network 22 and a visual display unit ("VDU') 20. The VDU 20 has both numbers and images to show visually the stock levels. The number "3-and three shaded rectangles 26 each indicate that three boxes 14 are present. The dashed box 28 which is unshaded shows that the lane 10 has capacity for a further box 14, but which is not currently being used. The rectangle 26 on the right is part-shaded to provide a visual representation of how full of parts the associated box is. This is accompanied by an explicit percentage figure On this case 67% -i.e. two-thirds full).

100391 A method of measuring the flow of parts in an assembly line according to a second embodiment will now be described with reference to Figures 3 to 6. Figure 3 shows an inclined flow path that, in use, functions as a gravity feed path for boxes 14 of parts for use in an -12 -assembly line. The assembly line may be similar to that described with reference to Figures 1 and 2. Thus, parts of the same type are fed via the flow path shown in Figure 3, in boxes 14 which form a queue. An operator takes parts from the box 14 at the front of the queue. Boxes 14 filled with parts join the back of the queue from time to time. The load is measured at the front of the queue by a load cell 16 from which a control unit can ascertain both (i) the number of boxes 14 in the queue, and (ii) the amount of parts in the box 14 at the front of the queue. [0040] The table below illustrates how the measured load might change when adding / removing a box 14 and when removing parts from the box 14 at the front of the queue. The table shows how the load changes over various steps of the method. The state of the lane 10 during four of those steps (steps 3, 7, 8, and 11) is shown by Figures 3 to 6, respectively.

Step Items in box No of other full Total load Change in Status of lane at front boxes in queue ILL' load (IN) 1 6 2 96 Three full boxes 2 5 2 91 -5 3 4 2 86 -5 State shown in Figure 3 4 3 2 81 -5 2 2 76 -5 6 1 2 71 -5 7 0 2 66 -5 State shown in Figure 4 8 No force on load cell -66 State shown in Figure 5 9 6 1 64 64 5 1 59 -5 11 4 1 54 -5 State shown in Figure 6 12 4 2 86 32 New box adding load [0041] The table represents a case where an empty box 4 gives rise to a measured load of 2N, and each part gives rise to an effective measured load of 5N per part At step 1, when three full boxes 14 are on the lane, each box 14 carrying six parts, the load measured is 96N. Steps 2 to 7 show how the load measured changes when parts are removed one-by-one from the box 14 at the front of the queue (the load reduces by 5N each time). At step 8, the operator lifts the front box 14 (now empty) from the lane 10 and thus, momentarily, the boxes 14 are no longer -13 -in contact with the load cell 16, which then measures no load (see Figure 4). Two full boxes 14 in contact with the load cell 16 give rise to a measured load of 64N, as per step 9. Steps 10 and 11 show how the load measured changes when two more parts are removed one at a time from the box 14 that is newly at the front of the queue (again, the load reduces by 5N each time). A new box 14 of parts is added (see Figure 6), but until it contacts the other boxes 14 in the queue no increase in load is measured. At step 12, the new box 14 makes contact such that the load contributed by the weight of the newly added box 14 increases the load measured. 100421 The local control unit is arranged to monitor the load measured by the load cell 16 over time and ascertain from such measurements both the number of boxes 14 and the amount in the front box 14. A sudden increase in the load measured, may be deemed as indicative of the number of boxes 14 in the lane 10 increasing by one, if the load increases by 32N, within a margin of error. A decrease in the measured load by 5N, or a multiple of 5N, (give or take a margin of error) is deemed to have resulted from the removal of the equivalent number of parts (calculated by dividing the decrease in the load by 5N). By keeping track of the number of parts in the front box 14, it may be that when the amount reaches zero and there is then an interruption in the measured load (drops suddenly to zero for example), that is deemed as having resulted from the empty box 14 being removed from the queue. Additionally, or alternatively, when the net load reduces by -2N, that is deemed as having resulted from the removal of the empty box 14. By keeping track of the number of parts in the front box 14, the control unit can readily recognise when a box 14 is removed from the queue by the operator. The control unit provides information -for example by a visual display -concerning how many boxes 14 are in the feed flow lane and how full the front box 14 is. Such information may also be collated from multiple flow feeds (lanes) such as for example (a) the rate of part usage from each lane, (b) the number of boxes 14 in each lane, (c) the amount of parts in the box 14 at the front of the queue of each lane, and (d) the amount of parts in all the boxes 14 in the queue of each lane. That information can then be assessed and/or used in a manufacturing resource planning system. Such a system can determine trends/patterns in the rates of consumption of parts in the lanes 10 and then use that data to manage the rate of supply of parts and/or boxes 14 of parts to the lanes 10 so as to avoid an inadequate supply of parts.

[00431 Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the -14 -invention lends itself to many different variations not specifically iflustrated herein. By way of example only, certain possible variations will now be described.

100441 The visual display of how many boxes are in a lane, and how much stock is in the front-most box, could be collated for multiple lanes and then displayed on a single local display unit, instead of there being one display unit per lane. The display may additionally, or alternatively, show the rate of supply of parts of a certain type to the lane concerned. The display may additionally, or alternatively, show the rate of depletion of parts of a certain type from the lane concerned.

[0045] Instead of, or in addition to, the central computer providing real-time information to managers directly through a visualisation dashboard, the computer could also provide such data to a manufacturing resource planning system. Such a manufacturing resource planning system may also be implemented on a computer, and would be arranged not only to receive such data concerning the stock levels / number of boxes / amounts of parts in the boxes, but also to output data and/or information which is then used, manually and/or automatically, to manage the flow of parts in the assembly line.

100461 The load measured could be measured in a direction different from that shown in the Figures. The load does not need to be measured in a direction parallel to the inclination of the flow path / feed lane.

100471 The load may be measured more or less frequently than every second. A sample rate of 10 Hz could be used for example -i.e. measuring the load every 0.1 seconds. However, it is generally not necessary to use such a high sample rate in assembly lines. Sample rates of once every 3-5 seconds would also be sufficient.

100481 Other embodiments of the invention are envisaged for use in assembly lines for vehicles other than aircraft. The invention may have application in the automotive industry for example. There may be application in relation to assembly of products not being vehicles. Some other example applications will now be described. One non-illustrated embodiment relates to use in storage industry (warehouses) to determine the stock of items in real time -using the same setup and principles. Another non-illustrated embodiment relates to use the retail industry -using same set-up and principles to gain real-time visibility of stocks. A yet further non-illustrated embodiment relates to use factory shipping/packaging -using same set-up and principles to gain real-time visibility of items to be packaged and shipped. Thus, such embodiments in -15 -general may be considered as relating a method of measuring the flow of items (e.g. items of stock) which are delivered to and then subsequently removed from a location, wherein the method includes (a) delivering such items in bins via at least one inclined lane to the location, the bins moving along the lane assisted at least in part by gravity, multiple bins forming a queue of bins in the inclined lane, (b) measuring a load at the front of the queue, and (c) using the load so measured to provide (i) an indication of the number of bins in the queue in the lane, and (ii) an indication of the amount (e.g. number) of items in the bin at the front of the queue. A manual operator may remove items from the bin at the front of the queue at the location, for example picking items of stock for subsequent delivery to a customer. It will be appreciated that features of the other embodiments and concepts described and claimed herein may be similarly broadened and/or included in this generalised method. For example, the supply management apparatus described above could take the form of a stock management system, wherein the system is for use in a setting where multiple inclined lanes feed items of stock to one or more locations, each lane being associated with a single type of stock item, the items being provided via bins, each lane being configured to accommodate multiple bins in a queue of bins and to allow items to be removed from the bin at the front of the queue, each bin carrying multiple items at a time to the location, and each lane being configured to be inclined so as to assist movement of the bins towards the front of the queue. Such a stock management system may thus also comprise, for each inclined lane, a load cell arranged to measure a load at the front of the queue of each lane. Such a stock management system may also comprise one or more processing units, which are arranged (i) to receive a signal from each load cell and from such a signal to calculate for each lane the number of bins in the queue in the lane, and the amount of items in the bin at the front of the queue, and which are arranged (ii) to output data providing information on one or more of (a) the amount of items of a certain type in one or more lanes (b) the rate of supply of items of a certain type to one or more lanes and (c) the rate of depletion of items of a certain type from one or more lanes.

[00491 Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are -16 -described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments. The term 'or' shall be interpreted as 'and/or' unless the context requires otherwise.

Claims

-17 -CLAIMSA method of measuring the flow of parts in an assembly line, wherein the assembly line includes at least one inclined lane that feeds parts to the assembly line, the parts are provided via bins that move along the inclined lane, the movement being assisted at least in part by gravity, multiple bins form a queue of bins in the inclined lane, and wherein the method includes the following steps: measuring a load at the front of the queue, and using the load so measured to provide (i) an indication of the number of bins in the queue in the lane, and (ii) an indication of the amount of parts in the bin at the front of the queue.
2. A method according to claim 1, wherein a processing unit receives a signal representative of the load so measured, and processes that signal in order to produce an output signal that includes both information concerning the number of bins in the queue in the lane, and the amount of parts in the bin at the front of the queue.
3. A method according to claim 2, wherein the processing unit monitors the load so measured over time and deems an increase in the load so measured as indicative of the number of bins in the lane increasing by one, but only if certain predefined criteria are met.
4. A method according to claim 2 or claim 3, wherein the processing unit monitors the load so measured over time and deems a decrease in the load so measured as indicative of a reduction in the amount of parts in the bin at the front of the queue.
5. A method according to any preceding claim, wherein the load measured at the front of the queue includes a component of the weight of each bin in the queue.
-18 - 6 A method according to claim 5, wherein the load measured at the front of the queue is measured in a direction that includes a component of the weight of each bin in the queue.
7. A method according to claim 6, wherein the load measured is the contact force between the front of the bin and a load cell.
8. A method according to any preceding claim, including providing a visual representation on a display unit of both the number of bins in the queue in the lane and the amount of parts in the bin at the front of the queue 9. A method according to any preceding claim, wherein the method is performed in respect of multiple lanes and the information on one or more of (a) the rate of part usage from each lane, (b) the number of bins in each lane, (c) the amount of parts in the bin at the front of the queue of each lane, and (d) the amount of parts in all the bins in the queue of each lane, is collated and processed by a computer system associated with the assembly line.10. A method according to any preceding claim, wherein the method includes determining data relating to the rate of consumption of parts in a lane and using that data to manage the rate of supply of parts and/or bins of parts to that lane so as to avoid an inadequate supply of parts from that lane.11. A method according to any preceding claim, wherein the method is performed in an assembly line for manufacturing at least part of a vehicle.12. A supply management apparatus for use on an assembly line, wherein the assembly line utilises multiple inclined lanes that feed parts to the assembly line, each lane being associated with a single type of part, the parts being provided via bins, each lane being configured to accommodate multiple bins in a queue of bins and to allow parts to be removed for use in the assembly line from the bin at the front of the queue, each bin carrying multiple parts to the assembly line, and -19 -each lane being configured to be inclined so as to assist movement of the bins towards the front of the queue, and wherein the supply management apparatus comprises: for each inclined lane, a load cell arranged to measure a load at the front of the queue of each lane, and one or more processing units, which are arranged to receive a signal from each load cell and from such a signal to calculate for each lane the number of bins in the queue in the lane, and the amount of parts in the bin at the front of the queue, and which are arranged to output data providing information on one or more of (a) the amount of parts of a certain type in one or more lanes (b) the rate of supply of parts of a certain type to one or more lanes and (c) the rate of depletion of parts of a certain type from one or more lanes 13. A supply management apparatus according to claim 12, wherein the apparatus includes one or more visual display units arranged to provide a visual indication, for each lane, of the number of bins in the queue in the lane and the amount of parts in the bin at the front of the queue.14. A manufacturing resource planning system implemented on a computer which is arranged to receive data from the one or more processing units of the supply management apparatus of claim 12 or claim 13 and to output information which is then used to manage the flow of parts in the assembly line 15. A processing unit configured to perform the function of one of more of the processing units referred to in any of claims 2 to 4 and 12 to 14 16. A method of adding a supply management function to an existing assembly line, wherein the existing assembly line utilises multiple inclined lanes that feed parts to the assembly line, each lane being associated with a single type of part, -20 -the parts being provided via bins, each lane being configured to accommodate multiple bins in a queue of bins and to allow parts to be removed for use in the assembly line from the bin at the front of the queue, each bin carrying multiple parts to the assembly line, and each lane being configured to be inclined so as to assist movement of the bins towards the front of the queue, and wherein the method includes adding a load cell to the front of each inclined lane, each load cell being arranged to measure a load at the front of the queue of the lane, and arranging one or more processing units to receive a signal from each load cell and from such a signal to calculate for each lane the number of bins in the queue in the lane, and the amount of parts in the bin at the front of the queue, and to output data that can then be used to manage the supply of parts to the assembly line I 7. A kit of parts comprising one or more processing units and one or more load cells, the processing units and one or more load cells being configured to be suitable for use in the method of claim 16.