Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
  • B07C1/00—Measures preceding sorting according to destination
  • B07C1/02—Forming articles into a stream; Arranging articles in a stream, e.g. spacing, orientating

Definitions

• the invention relates to a method and a device according to the preamble of claims 1 and 8.
• the mail items are fed through an input device to a mechanical storage path in which the mail items are moved at a predetermined speed, optical scanning by a scanner being carried out in the initial area of the storage space. While the shipment is in the storage path, the scanning result is processed further, in particular fed to a reading device that evaluates address information applied to the shipment surface. Before the mail items leave the storage path, the result of the reading device should be available in order to further distribute the mail items or to provide the reading result with corresponding sorting information.
• One problem with the automatic sorting of mail items in which information applied to the item surface is evaluated is to set the number of items per second fed to the storage area in such a way that the reading result is actually available before the items have left the storage area .
• an object of the present invention to provide a method and an apparatus suitable for carrying out the process apparatus with which it is achieved that the reading location x of the consignments in the storage segment between predetermined xo and x m ax remains.
• the invention is characterized in that an auxiliary control loop is introduced in such a way that the number y of uncoded mail items in the storage path is determined and fed back to the input station via a controller to generate the manipulated variable u.
• the reading power z of the reading device is applied to the reference variable of the auxiliary control loop via a characteristic element.
• an automatic address reader and / or a device for video coding is used as the reading device.
• a two-point controller is used as the controller in which the number y of uncoded mail items is fed back to generate the manipulated variable of the input station.
• the characteristic curve element has a non-linear characteristic curve.
• Fig. 1 is a schematic diagram of an address reading
• Video coding system
• Fig. 3 is a structural diagram of the control by feedback
• Fig. 4 shows the stationary behavior of the number not yet read
• Fig. 5 is a structural diagram of the complete control loop in one
• Fig. 7 shows the structure of the complete control loop in a combined address reading and video coding system.
• Fig. 1 shows the basic diagram of a combined address reading and video coding system.
• the mail items are separated and conveyor belts are transferred, which convey the letter through the system and form a mechanical storage path 20.
• the mail item surfaces are optically scanned by a scanner 30 and their images are transferred to an address reading device.
• the location at which a consignment is located in the storage path when the reading device delivers its result is hereinafter generally referred to as reading location x.
• OCR processing OCR
• video coding can be carried out by coding personnel.
• the location at which a program is located in the storage path when its eventual video coding processing has been completed is called the further location of the video processing (OVCR).
• the scanning result supplied by the scanner 30 is preferably fed to an image memory 40 and then fed to an automatic address reading and / or video coding device 50.
• the read result is fed to a result memory 60, which supplies sorting or printing information to further devices, which are not shown in FIG. 1.
• the entire device is controlled by a central processor unit 70.
• the reading device may be overwhelmed if the power u is too high, so that these results are only available when the associated programs have already left the storage path. Such programs cannot be sorted.
• the reading device may be under-challenged if the performance of the input station is set too low. The overall throughput of the system is then reduced unnecessarily, the reading location x being in the vicinity of the input device.
• the invention is based on the idea of not returning the controlled variables, namely x or OOCR or OVCR, as usual from this to determine a favorable performance of the input station, but instead to use auxiliary control variables.
• FIG. 2 shows the structural diagram of a plant according to FIG. 1. It is assumed that only one address reader is used, the z. B. according to a FIFO principle from the image memory and stores the read results in the result memory, regardless of whether the reading was successful or not.
• the differential equation x ( t) v zfi __ then applies to x or OOCR in a continuum approximation. ( D xw v d (x, t)
• the speed x (t) with which OOCR moves is given on the one hand by the transport speed v, which is assumed to be constant; on the other hand, this speed is counteracted by the processing power z (t) of the address reader, measured in programs / second, which is still to be divided by the concentration d (x, t) of programs, specified in programs per meter, in the storage path.
• Equation (1) thus changes into
• x (t) therefore follows a nonlinear differential equation 75 with variable dead time, in which the power u (t) of the input station and the processing power z (t) of the address reader are used as influencing variables come in, 78. Because of the integrator, the system is unstable.
• the controlled system according to equation 5 is difficult to control, in particular because of the variable dead time, since stability problems and slow transient behavior occur.
• ie y is the integral of the difference between the deduction power of the input station and the processing power of the address reader.
• y (t) is determined and reduced to u (t) via a controller 80, preferably a two-point controller.
• the two-point controller 80 switches the input station 10 to full withdrawal power u max as long as the measured value y of the storage path 20 is smaller than the target value w and stops the withdrawal completely as soon as y has reached the target value.
• the auxiliary control loop for y is time-optimal with the two-point controller 80, ie there is no other controller that can set the auxiliary control variable y to a predetermined soli value w in a shorter time.
• the auxiliary control loop is stable at the same time and is not susceptible to vibration due to its low order.
• the setpoint w is a function of the currently available processing power z (t) of the address reader.
• the instantaneous power z (t) is measured with a measuring element 90 at the output of the address reader, smoothing with a low-pass character taking place at the same time and applied via the non-linear characteristic curve of a characteristic curve controller 100 as setpoint value w (t),
• the measurement of the processing power, since reading results only occur at discrete times, is only possible by averaging over a predetermined time or a predetermined number of reading results. For example, when a coding result occurs, the time since the last occurrence of a result can be determined and its reciprocal can be formed, which is then a measure of the coding performance. When considering several coding results, an averaging, ie a low-pass effect, occurs in the measurement. Y is determined by reporting electrical components with the help of counters. For example, the input device issues a message as to how many items have been withdrawn while the reading electronics report each reading result. Therefore, the number of uncoded items can be determined by counting. As in FIG.
• the manipulated variable u (t) is traced back via a two-point controller 80.
• a suitable choice of the non-linear characteristic curve 100 results in a favorable course for x as a function of the stationary processing power.
• 6a shows qualitatively a preferred non-linear characteristic
• FIG. 6b shows the associated course of x according to equation (7). The result is that the length of the storage path is fully used for low processing powers z, for medium processing power x is approximately in the middle of the storage path, while x moves near the input station for high power z.
• the total throughput of a system controlled in this way is close to the ideally achievable throughput with a simultaneously low number of memory path overruns, that is to say the number of mail items for which there was no read result from the address reader when the memory path was left.
• the method described above can be adopted, the power z of the address reader being replaced by the power of the coding forces.
• Other parameters such as the memory path length and characteristic points of the non-linear characteristic, FIG. 6, are to be adapted to the typically longer time period for determining the address.
• the method according to the invention can also be used.
• determining the deduction aspects of both the address reader and the video coding device are taken into account. This is preferably done as follows:
• the regulation for the video coding area is designed so that the location of the video coding OVCR remains within the entire storage path. It must be taken into account that the number of video uncoded programs cannot be determined precisely, since not every program in the storage section has to be video-coded and the success or failure of the address reader is not known in advance, but yvideo can be predicted, namely as the sum of the number of programs with a negative result already processed by the address reader plus the number of programs for which the address reader has not yet received a result but for which a negative result is expected. This is the formula
• ⁇ QCR negatively denotes the number of programs for which a negative result of the address reader already exists but no video coding result yet
• yoCR denotes the number of programs for which there is still no result of the address reader.
• the forecast value 1 of the read rate for the not yet OCR processed broadcasts yrjCR w 'r obtained as an average of a certain number of address reader already processed broadcasts and that as positive for at predetermined times updated quotient of successfully processed broadcasts nrjCR, d is the total number of processed items ng esam t:
• the regulation for the video coding area generates a value wvjdeo ur
• Fig. 7 shows an embodiment of a complete control loop for a combination of address reader and video coding.
• the parts of the control loop for yrjCR completely adopted from FIG. 5 are shown in bold.
• the characteristic curve controller 100 or 1 10 in the graphic representation in FIG. 7 are to be understood such that they also include measuring elements with a low-pass effect.
• the feedback to u takes place via a controller 1 20.
• L (t) denotes the actual reading rate. This is the cause of one
• OCR-processed mail yoCR is accepted.
• u min (uQCR 'u Video)' st particularly useful when mainly unprocessed programs are to be avoided at the end of the storage segment.
• u uocR + u ⁇ / jdeo / 2, for example. In such a case, the circuit 130 must be modified accordingly.

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• Sorting Of Articles (AREA)
• Character Input (AREA)

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Family Applications (1)

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• 1994
  • 1994-06-03 DE DE4419430A patent/DE4419430A1/de not_active Withdrawn
• 1995
  • 1995-05-24 AT AT95920879T patent/ATE169527T1/de not_active IP Right Cessation
  • 1995-05-24 CA CA002191976A patent/CA2191976A1/fr not_active Abandoned
  • 1995-05-24 JP JP50027596A patent/JP3691064B2/ja not_active Expired - Lifetime
  • 1995-05-24 CN CN95194027A patent/CN1066352C/zh not_active Expired - Lifetime
  • 1995-05-24 DE DE59503180T patent/DE59503180D1/de not_active Expired - Lifetime
  • 1995-05-24 US US08/750,170 patent/US6169936B1/en not_active Expired - Lifetime
  • 1995-05-24 EP EP95920879A patent/EP0762944B1/fr not_active Expired - Lifetime
  • 1995-05-24 WO PCT/EP1995/001976 patent/WO1995033580A1/fr active IP Right Grant

Non-Patent Citations (1)

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