Orienting a scanning device with respect to a target location

Disclosed is a method for a scanning device to tell its user how to best orient the scanning device to scan a target location. The user approaches the target location and initiates a scan. The results of the scan are analyzed and compared to information about the target location. Based on the analysis, the user is told how to re-orient the scanning device, if that is necessary to achieve an acceptable re-scan of the target location. In a preferred embodiment, a screen on the scanning device presents a two-dimensional map based on the scan results and on the known relative locations of the target location and of nearby non-target locations. Locations on the map are highlighted to tell the user the results of the scan and to direct him to re-orient the scanning device if necessary.

FIELD OF THE INVENTION

The present invention is related generally to scanning devices (e.g., RFID and bar-code readers) and, more particularly, to using such devices for establishing location.

BACKGROUND OF THE INVENTION

Shoppers are familiar with the machine-readable tags, such as laser-readable bar codes or Radio Frequency Identification (“RFID”) tags, attached to products in stores. These tags are read during checkout, and an accurate list of the items purchased is presented to the user, along with billing information and, sometimes, related advertising.

In addition to making customer check-out faster and more accurate, these product tags help the merchant to track his inventory. By knowing which products and how many of them leave the store, an automated system can place re-stock orders when supplies are running low or alert the merchant when a particular product is selling poorly.

In a related scenario, a merchant or wholesaler actively inventories the stock on hand by scanning the machine-readable tags in a given location (e.g., on a particular shelf in a warehouse). The read-out (from the tags) of the items actually present can be cross-referenced against a list of items presumed to be present (produced by, e.g., an inventory system that tracks products coming into and products leaving a given area). If discrepancies due to theft or due to inaccurate scanning are found, they can be corrected.

Taking inventory by scanning for machine-readable tags placed on the items has some shortcomings, however. In addition to the obvious problems of missing, duplicate, or wrongly applied tags, the nature of the scanning process itself allows for some inaccuracies. When a user initiates a scan from a hand-held scanning device, the device makes a record of all of the tags that it “sees” during the scan. But it is not always certain that the scan registers all of the tags in the location that the user intended to scan and registers none of the tags in locations that the user did not intend to scan. There are several possible reasons for this. Some scanners (e.g., RFID scanners) can identify tags at a wide angle from the direction in which the scanner is pointing when the scan is initiated. Also, the range of the scan can vary from moment to moment depending on environmental circumstances. (Radio noise can limit the effective range of radio-based scans, while dust can limit laser scans.) These and other characteristics of the scanners typically in use today mean that the user may not know exactly the scope of the scan. For example, the user may wish to inventory the products on one shelf in a warehouse. However, if the user is not very careful with positioning and pointing the scanner during the scan, the scanner may miss some of the items on the shelf or may pick up items on other, nearby, shelves.

BRIEF SUMMARY

The above considerations, and others, are addressed by the present invention, which can be understood by referring to the specification, drawings, and claims. According to aspects of the present invention, a scanning device tells its user how to best orient the scanning device to scan a target location. (For example, the target location can be a shelf or a bin in a warehouse, the location marked with RFID chips or laser-readable bar-codes.) The user approaches the target location and initiates a scan. The results of the scan are analyzed and compared to information about the target location. (This information may be downloaded to the scanning device from a central server that hosts a database of location information for the premises.) Based on the analysis, the user is told how to re-orient the scanning device, if that is necessary to achieve an acceptable re-scan of the target location.

For example, if the scan results include the target location but also include a location other than the target location, then the orientation of the scanning device was close to acceptable but not quite good enough. The central server knows the relative locations of the target location and of the scanned non-target locations. Based on this information, the user is told how to re-orient the scanning device so that the next scan reads the target location but not the non-target locations.

Some scanning technologies provide a measurement of distance from the scanning device to the scanned tag. For RFID tags, some scanners record the strength of the signal returned from every RFID tag seen during the scan, and this signal strength serves as a proxy for the distance. Other proxy distance measurements are possible for this and for other scanning technologies. Some embodiments of the present invention use these distance measurements to, for example, ignore scanned tags that are farther away than a threshold distance. Also, a scan may be deemed to be acceptable when the target location is closer by a significant amount than any non-target scanned location.

Several possibilities are contemplated for a user interface that tells the user the results of a scan. A very simple interface could present a sound or light that tells the user roughly how close he is to an acceptable orientation. (E.g., a red light means the scan did not read the target location at all; yellow means the target location was read but so too were non-target locations; and green means the scanner orientation was acceptable.) In a preferred embodiment, a screen on the scanning device presents a two-dimensional map based on the scan results and on the known relative locations of the target location and of nearby non-target locations. Locations on the map are highlighted to tell the user the results of the scan and to direct him to re-orient the scanning device if necessary.

DETAILED DESCRIPTION

Turning to the drawings, wherein like reference numerals refer to like elements, the invention is illustrated as being implemented in a suitable environment. The following description is based on embodiments of the invention and should not be taken as limiting the invention with regard to alternative embodiments that are not explicitly described herein.

FIG. 1apresents a stylized layout of a typical warehouse or store100. A warehouse100often includes numerous rows102of shelves or bins104. To allow the warehouser to track the merchandise, each type of merchandise is assigned to be stored on one or more particular shelves104.

Inventorying the merchandise stored in the warehouse100is an ongoing task. As part of the inventory process, the contents of the shelves104are checked to make sure that all of the merchandise is properly stored and to check that the expected amount of merchandise is present in the warehouse100. To perform the inventory, a user is given a hand-held scanning device106. The scanning device106scans for tags affixed to the merchandise and records the tags found during the scan. Some scanning devices106use a laser to read bar-code tags (e.g., the UPC tags found on grocery-store items); other scanning devices106use a radio to read RFID tags.

The scanning device106may communicate with one or more wireless hubs108(e.g., Wi-Fi hubs) installed throughout the warehouse100. The scanning device106can communicate through the hubs108to a central server110that contains inventory information and a current map of the shelves in the warehouse100. In many embodiments, the scanning device106holds a current map of the entire warehouse100; the map is updated as needed by the central server110. The central server110can send commands to the user of the scanning device106and can receive the results of the scans.

When the user wishes to inventory the items stored on a particular shelf104(called the “target shelf” or “target location”), the user orients the scanning device106and initiates a scan. However, the scan will be accurate only if the user correctly orients the scanning device106with respect to the target location104during a scan. If the scanning device106is not correctly oriented, then the scan may miss items actually present on the target shelf104or may register items on neighboring shelves.

Aspects of the present invention help the user to correctly orient the scanning device106so that he can get an accurate scan of the target location104.FIG. 1bshows an array of shelves104. To facilitate proper orienting of the scanning device106, the shelves are tagged with RFID or laser-scan tags114. (FIG. 1bshows one embodiment of the tagged shelves104, but the positioning and number of tags114can be varied to optimize the detection of the tags114, the variations among embodiments based on particularities of the scanning environment.) As explained in greater detail below, a scan registers these tags114(as well as registering tags on merchandise). The scanning of these tags114is used to determine, and to correct if necessary, the orientation of the scanning device106with respect to the target location104. Note that the labels112on the shelves104(e.g., “C1R1” for “column1, row1”) are for purposes of the present discussion and need not actually appear on the shelves104in the warehouse100.

FIG. 2shows some relevant elements of a typical scanning device106. A transceiver200allows communication with the hubs108for communication with the central server110and for roughly determining the position of the scanning device106, as discussed below. A second transceiver204performs the scan (laser or radio). A processor202runs the two transceivers200,204and controls a user interface206. The user interface206receives commands from the user (e.g., a command to initiate a scan) and presents results of the scan. Embodiments of the user interface206are discussed below.

The flowchart ofFIGS. 3aand3bpresents one embodiment of the methods of the present invention. The user of the scanning device106is told to scan a particular shelf104. (The command could come from the central server110and be delivered to the scanning device106via a hub108.) In step300, the user approaches the target location104. For example, the user may have in his head the general layout of the warehouse100and may know how to get reasonably close to the target location104. Also, for many warehouses100a map has been made that correlates received signal strengths from the wireless hubs108with a physical location in the warehouse100. Using this map, the scanning device106can analyze the signals it is receiving from the hubs108and know its rough location in the warehouse100. The scanning device106can then tell the user how to come close to the target location104. (Generally speaking, GPS does not work very well in a typical warehouse100.) In some embodiments, the central server110knows approximately where the user is currently standing (e.g., near the previous target location) and can send instructions to the user to get him close to the next target location104. At the end of step300, the user is within a couple of meters of the target location104.

For purposes of the present discussion, assume that the user is now facing the array of shelves shown inFIG. 1b, and assume that the target location is C2R1.FIGS. 4a,4b, and4cillustrate one possible user interface206of the scanning device106. On a screen of the scanning device106is shown a two-dimensional display of the local environment. InFIG. 4a, the target location C2R1is highlighted for the user. (In actual embodiments, the highlighting can be a bright color, e.g., blue, rather than the diagonal stripes ofFIG. 4a.) A simpler alternative user interface206is described below.

In step302, the user orients the scanning device106as best he can with respect to the target location104and, in step304, initiates a scan.

The scanning device106receives the results of the scan in step306. At a minimum, the results of the scan include a list of tags read during the scan. In some embodiments, an actual distance or a “proxy” distance is associated with each tag on that list. This measures the approximate distance from the scanning device106to the tag at the time of the scan. A measurement is a “proxy” distance when the scanning technology does not measure this distance directly. Some RFID technologies record the strength of the signal returned from each tag read during the scan, and this signal strength can be used as a proxy distance measurement (of course, a weaker signal means a greater proxy distance). Other RFID technologies run a sequence of scans at different power levels to measure proxy distances. Tags read with a lower power are considered to be nearer than tags that can only be read with a higher power. Other proxy distance measurements are possible and may be used. When scanning devices106that determine actual distances become more widespread, their distance measurements can replace these proxy distances. While distance measurements, whether actual or proxy, are very useful (see step310below), embodiments of the present invention are also useful even with scanning devices106that provide no distance measurements of any kind.

In step308, the results of the scan are analyzed, either locally by the processor202of the scanning device106or remotely by the central server110. Because any merchandise tags registered during the scan are irrelevant for purposes of properly orienting the scanning device106, these tags are ignored for now, and the following discussion only concerns those tags114affixed to specific shelves104.

Properly speaking, step310is an optional part of the analyzing step308. If distance measurements are available (either actual or proxy), then those tags114read during the scan that are too far away (e.g., more than a first threshold distance away) can be ignored during the analysis of step308.

The set of location tags114read during the scan (excluding the tags filtered-out in step310, if any) is analyzed in step308to determine whether or not the orientation of the scanning device106during the scan was appropriate. In general, there are three possible results of this analysis (that is, three possible “determined presence conditions” of the target location104): (1) The target location104was not definitively found. (“Definitive” here means that the signal strength of the target location104is greater than the first threshold mentioned above.) (2) The target location104is found definitively but not uniquely. (3) The target location104is found both definitively and uniquely. Result (3) is the desired one.

Different analysis algorithms can be used to characterize the results of the scan into one of the three possible presence conditions mentioned above. As a simple example, the target location104is found definitively and uniquely if its location tag114is the one and only location tag remaining on the scan list. If proxy distances are available, then the target location104can also be found definitively and uniquely if (a) its location tag114is on the list and (b) the proxy distance for the target location's tag114is less, by at least a threshold amount, than the distance of any other location tag on the list.

Again if distance measurements are available, the target location104is found definitively but not uniquely if (a) its location tag114is on the list and (b) the proxy distance for the target location's tag114is not less, by at least the threshold amount, than the distance of at least one other location tag on the list.

In step312, the determined presence condition of the target location104is presented to the user via the user interface206of the scanning device106. A very simple user interface206could simply indicate which of the three possibilities applies. For example, a “stoplight” could be shown: Red means not definitively found, Yellow means found definitively but not uniquely, and Green means found definitively and uniquely. Alternatively, a specific sound could be played to indicate the determined presence condition.

A more useful two-dimensional interface206is illustrated inFIGS. 4a,4b, and4c. In this interface, the boxes representing the nearby shelves are colored to indicate the determined presence condition. In one embodiment, the following rules are used for the coloring:Color gray any shelf whose location tag114either was not read during the scan or that was excluded from consideration in step310. Also, color all shelves gray if the target location104was not read during the scan.If the target location104was read during the scan, then:Color yellow any shelf whose location tag114generated a fairly strong signal (e.g., above a second threshold).If the target location104returned a very strong signal (e.g., above a third threshold), and if that signal is significantly stronger than the signals returned by neighboring locations, then color green any shelf whose location tag114generated a very strong signal.If more than one green shelf is found, then re-assign the green shelves to yellow.
Using these rules, the orientation of the scanning device106was close but not exact (i.e., the target location104was found definitively but not uniquely) if the user interface106shows a number of yellow boxes.FIG. 4bshows this possibility (pretend that the boxes representing shelves C2R1and C2R2are colored yellow).FIG. 4cshows the case where the target location104was found definitively and uniquely (box C2R1is colored green).

The specific user interface206ofFIGS. 4a,4b, and4cillustrates a useful function not available with the simpler “stoplight” interface. ConsiderFIG. 4b. The user, on seeing this on the screen of the scanning device106, knows not only that the most recent scan was close but not quite good enough, but he also sees what was wrong with the scan. Clearly, the scanning device106that produced the results ofFIG. 4bwas pointed too low. Thus, this user interface206can tell the user (in step314) how to correct the orientation of the scanning device106to get a better scan.

In step316, the user repeats the scan, if necessary, until a good result (target location104found definitively and uniquely) is achieved. When a good result is achieved, the user knows that the list of merchandise tags found in the scan (the list filtered, as appropriate, for actual or proxy distance) truly represents the entire contents of the target location104and does not include merchandise tags from neighboring shelves. Of course, the methods of the present invention are not limited to the case of taking inventory but are useful whenever a target location needs to be scanned for whatever reason.

In view of the many possible embodiments to which the principles of the present invention may be applied, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of the invention. For example, other user interfaces employ other formats to present the scan results. Therefore, the invention as described herein contemplates all such embodiments as may come within the scope of the following claims and equivalents thereof.