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Publication numberUS3691398 A
Publication typeGrant
Publication dateSep 12, 1972
Filing dateJun 15, 1970
Priority dateJun 15, 1970
Also published asCA944285A, CA944285A1, DE2129308A1
Publication numberUS 3691398 A, US 3691398A, US-A-3691398, US3691398 A, US3691398A
InventorsBurch Arthur R
Original AssigneeClark Equipment Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Station address and control system for material handling vehicles
US 3691398 A
Abstract  available in
Images(3)
Previous page
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Burch 51 Sept. 12,1972

[ STATION ADDRESS AND CONTROL SYSTEM FOR MATERIAL HANDLING VEHICLES [72] Inventor: Arthur R. Burch, Plainwell, Mich.

[731 Assignee: Clark Equipment Company,

- Buchanan, Mich.

221 Filed: June 15,1970

211 Appl. No.: 45,981

[521 US. Cl "307/110, 214/16.4 A [51] Int. Cl. ..H0lh 35/00 [58] Field of Search ..214/l6.l, 16.4 A, 16.4 R;

Primary Examiner-Herman J. Hohauser Attorney-Kenneth C. Witt, John C. Wressler, Robert J. Norton and Lewis J. Lamm [5 7] ABSTRACT An automatic storage system of the type using a material handling vehicle movable to a selected one of a large number of storage bins on command is disclosed with an improved station address and control system for the vehicle. The automatic control means for the vehicle reads the address of a station while it is parked therein or while it is moving therethrough toward a designation station in order to develop a control signal for the motive power means of the vehicle. Improved address means at each station includes a plurality of binary code elements in a predetermined array. A transducer on the vehicle coacts with the address means at each station and includes a plurality of sensors disposed in an array corresponding to the code element positions in the address means. Each of the sensors is effectivelyv connectable with the control means for the motive power means of the vehicle and a strobe signal element on each address means and a strobe sensor on the transducer are operative to connect the sensors to the control means for simultaneous readout of the address. in the address means the code signal elements take the form of plates or vanes of magnetic material. The sensors on the transducer are comprised of a magnetic reed switch with a permanent magnet mounted in spaced relation with an air gap therebetween and adapted to accommodate the magnetic vanes corresponding thereto.

14 Claims, 8 Drawing Figures PATENTEDSEP 12 1912 3.691. 398

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5M/% Ma ORNEY PATENTEDSEP I 2 I972 SHEET 3 or 5 NIULTIVIDRATOR COUNTER 7 I I I I I I I I I I I 1 v I A OUNT 864- I C L COINCIDENCE I [66 DETECTOR 50 226 I ,L L FINE I I Yea L STATION 5 I DESIONATOR +TRANSDUCERE COILISCUIBIENC E dag DETECTOR Z; 196 DRIVING [MI /72 [55 MEANS M M #4 20% zzo 2/2) DRMNG 300 I f l CONTROL INTERVAL CIRCUIT RIRRLE fZ/ SPEED MEANS I .208 COUNTER SELECTION {88/1 I CIRCUIT DIRECTION P SENSING I v INVEN'IUR. CIRCUIT Jrar Q are 156 j 8 BY ATTO RNEYS r 1 STATION ADDRESS AND CONTROL SYSTEM FOR MATERIAL HANDLING VEHICLES This invention relates to control systems for material handling vehicles and, more particularly, it relates to the station address readout means and the control system therefor. I

Automatic warehouse or storage systems have been developed in which a very large number of storage bins are arranged in rows and columns on each side of multiple access aisles and are served by automatically controlled material handling vehicles. Such a vehicle, commonly called a stacker vehicle, is adapted to pick up a material unit at a load station and to move under automatic control to a destination station and deposit the material unit in the storage bin at such station. Similarly, the stacker vehicle may automatically pick up 'a material unit from a storage bin at any station and move automatically. to the load station or to another storage bin and deposit the material unit. Such a system has been developed in which the automatic control means for the vehicle reads the addresses of the stations whilethe vehicle is enroute for controlling the motive power means of the vehicle. Such a system is disclosed in US. Pat. No. 3,503,530 issued to A. R. Burch et a]. on Mar. 31, 1970 for Transfer Cart for Transferring an Article Handling Vehicle Between Aisles of a Warehouse".

"This invention resides in an improvement in such systems for the automatic control of the material handling vehicle. According to the invention there is provided improved address means at each station which permits the readout of the station address while the vehicle is moving through the station or is stopped at the station. .This is accomplished by an address means which includes a plurality of binary code elements in a predetermined array andv a transducer on the vehicle which coacts with the address means at each station with a plurality of sensors disposed in an array corresponding to each possible position of the code elements in the address means. Each of the sensors is operatively connectable with the control means and a strobe signal element adjacent each address means together witha strobe element sensor on the transducer is operable to' connect the address sensors to the control means for simultaneous readout of the address.

Further, in accordance with the invention, there is provided an address means suitable for a system utilizing a very large number of stations and which does not require a high degree of positional accuracy in installation. Furthermore, the address means are of rugged construction and are economical and simple to install and maintain. This is provided by an address means using an array of passive code elements, preferably arranged in a two-dimensional array and representing a binary code identification'of the address. The transducer is mounted on the vehicle and includes active sensors corresponding to each of the plural positions of the code elements and disposed in the same predetermined array. Each of the sensors is adapted to change from a first state to a second state when a passive code element is disposed adjacent to it. In a preferred embodiment the code elements take the form of plates or vanes of magnetic material aligned parallel with each other in the direction of vehicle, travel. In the transducer, each active sensor takes the form of a magnetic reed switch and a permanent magnet mounted in spaced relation with an air gap therebetween adapted to accommodate the code element corresponding thereto. Thus, a relatively small number of active sensor elements is required in the transducer and they may be connected to the control means when the readout signal or strobe signal is produced by the strobe element and transducer to provide a parallel readout of the address. The sensitivity of the magnetic reed switches to changes in magnetic field intensity permit the use. of an air gap which is large relative to the thickness of the magnetic plates and thus the code elements need not be accurately positioned with reference to each other and the transducer path. By reason of the two dimensional array of the code elements an address pan of standard size may be used at each station and will accommodate in binary code form the required code elements for a very large number of addresses without requiring a large space or prominent mounting position at the stations.

A more complete understanding of this invention may be obtained from the detailed description which follows taken with the accompanying drawings in which:

FIG. 1 is an end elevation of a storage structure and a stacking vehicle therefor;

FIG. 2 shows the structure of a station address means together with the transducer mounted on the vehicle;

FIG. 3 is a side elevation of the storage structure including a view of the station address means;

FIG. 4 shows the structure of the station address means in detail;

FIG. 5 shows a view of the station address means and the transducer means in coacting relationship;

FIG. 6 shows an elevation view of the transducer;

FIG. 7 is a view taken on line 7-7 of FIG. 6; and

FIG. 8 is a block diagram of the electronic control system for the stacker vehicle.

Referring now to the drawings, there is shown an illustrative embodiment of the invention in an automatic warehouse system wherein a self-propelled stacker vehicle is adapted to transport a material unit between any selected storage bin and a load station or between two storage bins. Control means for the vehicle includes address means at the stations and a transducer on the vehicle adapted to coact therewith so that the addresses of the stations may be read while the vehicle is enroute or at a standstill in a given station. The control system in which the invention is embodied is adapted to exercise control over the vehicle in a single plane, i.e., the horizontal motion of the vehicle in the direction of an aisle between adjacent storage structures. The vehicle control in this horizontal plane is sometimes referred to as longitudinal control". It will be appreciated as the description proceeds that the invention may be applied in the same manner tocontrol vehicle motion along other axes or in other planes such as vertical or lateral motion of the vehicle.

Referring now to FIG. 1, a warehouse adapted for automatic deposit and retrieval of material units includes a storage structure with bin assemblies 10 and 12 mounted on the warehouse floor 14 with an access aisle 16 therebetween. The bin assemblies 10 and 12 may be of identical construction and a multiplicity of such bin assemblies may be used in a given warehouse depending upon the capacity required. The bin assembly 10 is shown in side elevation in FIG. 3 and comprises vertical columns 18, which may extend from floor to ceiling in the warehouse, and a set of vertically spaced transverse beams 20 together with suitable sway braces 22. The columns 18 and the beams 20 define a multiplicity of storage bins which are disposed in a rectangular array of columns and rows of bins. A column of bins is located at station A wherein a bin is provided at five different vertical levels corresponding to the transverse beams 20 which together with the columns 18 define bins Al, A2, A3, A4 and A5. Similarly, a column of bins is provided at stations B, C, D, etc., with individual bins at the different vertical levels and thus providing rows of bins A1, B1, C1, D1, etc., and a row of bins A2, B2, C2, D2, etc. Similarly, the bin assembly 12 comprises a multiplicity of bin columns at the respective stations A, B, C, D and E, etc., and a plurality of bin rows at the vertical levels of Al, A2, A3, A4 and A5. The bins in the two bin assemblies l and 12 are distinguished from each other by the convention of identifying the bins by station number, vertical level and by designation of left or right side of the aisle, when looking down the aisle from a load station 24, which is considered to be the head of the aisle. For example, a material unit 26 is shown in FIG. 3 in bin B2, i.e., station B, second level on the left side. Because of the very large number of stations which may be employed in a single warehouse, it is desirable to utilize an address number to identify the different stations. In order to provide for automatic readout of the address, it is convenient to encode the address number in binary form and to identify the station for manual reading in binary coded octal form.

In order to deposit and withdraw material units from any selected bin in the bin assemblies and 12, a material handling or stacker vehicle 28 is provided for movement up and down in the aisle 16 to any station. The stacker vehicle comprises an undercarriage 30 with a set of wheels 31 and 32 which are supported upon rails 33 and 34 for motion along the aisle. The stacker vehicle includes a superstructure or mast 36 on the undercarriage 30 which extends to an upper track 38 mounted overhead in the aisle 16 which receives an idler wheel 40 for stabilizing the mast of the vehicle. The stacker vehicle is self-propelled and includes a traction motor 42 which is coupled through a power transmission 44 to the traction wheels 32. The traction motor 42 is an electric motor and is suitably supplied with electric power through a trolley system, not shown. Additionally, the stacker vehicle comprises an elevator 46 which is movable vertically in the mast 36 and may be positioned at any bin of the bin assemblies.

In order to identify a large number of stations in the warehouse, it is desirable, to assign an address number to each station and to encode the addresses in binary form to permit automatic reading of the addresses. For this purpose an address means is provided at each station of the bin assembly. The address means comprises address signal devices 50, 52, 54 and 56, etc., at the stations A, B, C, D, etc., as shown in FIG. 3. The signal devices utilize an array of binary storage elements of the noncontacting type and which are especially adapted for the rugged environment of an automatic warehouse or storage system. Thus, the signal device is adapted to coact with a'sensing means or transducer 60 which, as shown in FIG. 2, is mounted upon the side of the stacker vehicle for the sensing or readout of the signal devices 50, 52, 54, etc. The transducer 60 is a proximity detector which, as described subsequently, includes magnetic field producing means and magnetic field sensing means, or responds to the presence and absence of a magnetic field and the signal device is adapted to alter the magnetic field in accordance with its encoded address number. As shown in FIGS. 2 and 3, the signal devices 50, 52, 54, etc., are mounted on the columns 18 of the respective bins or stations at a level just below the transverse beams 20 of the lowermost bins. The transducer 60 is mounted on the left side of the stacker vehicle at a position which is in alignment with the signal devices and which is adjacent thereto in a given station. The positioning and spacing of the signal devices and the transducer is such that the stacker vehicle may move through the stations with the signal device and transducer disposed close enough to permit the desired coaction but without any interference or physical engagement therebetween.

The construction of the signal devices 50, 52, 54, etc., is represented by signal device 50 which is shown in detail in FIGS. 4 and 5. The signal device 50 comprises a support plate 62 suitably of metallic construction which is adapted for mounting on the columns 18 adjacent the respective stations. The support plate 62 is suitably mounted by screw threaded fasteners 64 which extend through slots in the plate to engage the column 18 and provide for adjustable positioning of the signal device in the direction of the aisle 16. The support plate includes a matrix area 66 which is adapted to accept an array of binary code elements at predetermined positions within the matrix. In the illustrative example there are nine such positions labeled a throughh and j within the matrix. The positions a through h represent information bits and the position j represents a parity bit. The positional significance of the bits is assigned in ascending order from a to h so that position a represents the least significant digit and position h represents the most significant digit. Thus, a matrix with eight bit positions having position coefficients ranging from one to 128 and a maximum number of 255 station addresses within a given aisle is adapted to accommodate a large number of storage bins in each aisle. The two binary conditions (1 and O) of each bit position in the address signal device is represented by the presence or absence of a code element at the bit position. Such a code element takes the form of a plate or vane 70 which is constructed of magnetic material having a high permeability relative to that of air, such as sheet steel. The vane 70 shown in bit position a in FIG.4 comprises a sheet metal plate of sufficiently heavy gage to insure rigidity and having a mounting flange suitably riveted to the support plate 62 so that the vane extends in a direction normal to the support plate and in a horizontal plane. As illustrated in FIG. 4 the address of station A, represented by signal device 50, is encoded by the presence of a single code element or vane 70 which is located in the bit position a. The remainder of the bit positions are illustrated by the indication of vanes in phantom lines thus showing all possible positions for vanes in the matrix area 66 for use in designating a station address. Thus, for a station designator with a single vane in the bit position a, the address would be read in decimal form as station No.1. It will be appreciated that by providing the other address signal devices 52, 54, 56, etc., with vanes positioned selectively in the bit positions, the desired station number may be designated. For, example, with a vane in positions a, b, d, e and g, the address in decimal form is station No. 91 and in octal form is station No. 133. The parity bit position j is provided with the address bit positions for use in checking the accuracy of the readout in a conventional manner. The parity bit .position is provided with a vane in each address wherein the number of bit positions occupied by a vane is an even integer so that the station designator matrix area 66 is always occupied by an odd number of vanes.

In addition to the station designator matrix area 66,

each of the signal devices includes a strobe element in the form ofa vane 72 which is located at a longitudinally central position on the support plate 62. The strobe vane 72, as will be described hereinafter, is adapted to coact with the transducer so as to enable parallel readout of the station address, i.e., to initiate the sensing bythe transducer of the presence or absence of a vane in all of the positions a through h and j simultaneously.

Additionally, the address signal device is provided with position signal elements in the form of null position vanes 74 and 76. The vanes 74 and 76 are of the same structure as the other vanes but are positioned at the uppermost level on the support plate 62 and are symmetrically disposed with respect to the vertical centerline thereof. The null position vanes are adapted to coact with sensors on the transducer and produce a signal condition for the logic control system which is indicative 'of positioning of the stacker vehicle at a prescribed location at a given station.

The transducer 60, which is adapted to read out the signal devices at the various stations will be described with reference to FIGS. 5, 6 and 7.' The transducer includes sensing means which are responsive to the presence or absence of a magnetic field and function in the manner of a proximity detector with respect to the address signal device. As shown in FIG. 5, the transducer 60 comprises -a support plate 78 suitably of metallic construction which is formed with a laterally extending protective flange 79. The support plate 78 is mounted on the vehicle body by support brackets 80 by screw threaded fasteners 81 which extends through slots in the support plate 78 into engagement with the brackets 80. Thus, the transducer is adapted for limited positional adjustment in the vertical direction on the vehicle body so as to permit alignment thereof with the station address signal devices.

The transducer 60 further includes plural sensors located at predetermined positions in an array corresponding to the code element positions in the address signal device. Thus, as illustrated in FIG. 6, the transducer is provided with sensors in a station address readout matrix area 82 with positions a through it and position j' which are disposed in a mirror image array of the bit positions a through h and j of the station designator matrix area 66. At each of the readout sensor positions in the transducer there is provided a vane sensor in the form of a magnetic field detector. A sensor 84 at the position a comprises a magnetic field producing means in the form of permanent magnet 86 of bar shape and a magnetic field responsive means in the form of a magnetic reed switch 88 which are disposed oppositely and spaced apart to accommodate a magnetic vane therebetween. The sensor 84 includes a nonmagnetic body, which in its entirety is of E configuration as shown in the side view of FIG. 5. The body portion is constructed of a nonmagnetic material such as aluminum or a molded resin and is adapted to support the permanent magnet 86 in the center leg 90 thereof. The magnetic reed switch 88 is supported in a slot on the inner side of the outer leg 92 while the body is secured to the support plate 78 by suitable fasteners extending through the base or bridging portion between the legs of the body. As shown in FIG. 7 the magnetic reed switch 88 is a conventional type of single pole, two terminal switch wherein a reed type armature is adapted to open the contacts in the presence of a magnetic field at predetermined field strength and to close the contacts in the absence thereof. Thus, the

sensor 84 includes all of the active elements required for detecting the presence of the code element in the form of a magnetic vane. As described, it may be regarded as being of U-shaped configuration with a permanent magnet in one leg 90 and a reed switch in the other leg 92. Thus, as indicated in FIG. 5, the vane of the address signal device 50 extends into the space between the legs and 92 and hence between the permanent magnet 86 and the reed switch 88 of the sensor.

In the absence of the vane 70 between the legs of the sensor, the field of the permanent magnet is of sufficient intensity in the vicinity of the reed switch 88 to cause opening of the contacts thereof. When the vane 70 is inserted between the legs of the sensor 84 it is effective to distort the magnetic field by providing a short circuit path, i.e., a path of low magnetic reluctance for the magnetic flux from the permanent magnet 86 thereby reducing the flux field intensity in the vicinity of the reed switch below the predetermined value and the reed switch contacts are closed.

It is to be noted that the transducer 60 includes another sensor 96 in the position d which is of unitary construction with the sensor 84. The sensor 96 includes the permanent magnet 86 in common with the sensor 84 and also includes a separate reed switch 98 which is mounted in the other outer leg 100 of the U-shaped body which supports the sensors. Thus, the sensor 96 is also of U-shaped configuration including a center leg 90 and the outer leg 100 which are supported by the base portion extending therebetween and connected with the support plate 78. The sensor 96 is adapted to operate in the same manner as sensor 94 and thus responds to the presence of a vane at the position d, when the address signal device and transducer are properly aligned, to close the reed switch 98.

The transducer 60 also includes sensors of similar construction at the remaining predetermined positions on the support plate 78. A sensor 104 is located at the position b and includes a permanent magnet 106 and a reed switch 108 which are adapted to detect the presence or absence of the vane at the position b of an address signal device when it is properly aligned with the transducer. In a similar manner a sensor 110 is located at position 0' and includes a permanent magnet 112 and a reed switch 114 and is adapted to detect the presence or absence of a vane at position 0. A sensor 116 which includes the permanent magnet 112 and a reed switch 118 at position e responds to the corresponding vane of an address signal device. Similarly, there is provided a sensor 120 with permanent magnet 122 and reed switch 124 at position f and a sensor 126 including the permanent magnet 122 and reed switch 128 at position h, for the corresponding vanes at positions f and h, respectively.

The remaining sensors on the transducer operate on the same principle as those just described but utilize a separate magnet for each reed switch and are formed as separate U-shaped configurations. The position g is occupied by' a sensor 130 which includes a permanent magnet 132 and a reed switch 134 and responds to the presence or absence of the corresponding vane when aligned with an address signal device. A sensor 136 is located at position j and includes a permanent magnet 138 and a reed switch 140 for sensing a parity vane at position j on the signal device.

In order to sense the strobe vane 72 on the signal device a sensor 142 is positioned on the vertical center line of the transducer 70 for alignment with the strobe vane and comprises the permanent magnet 106 and a reed switch 143. To provide for sensing of the null position of the transducer with reference to the address signal device for accurate positioning of the stacker vehicle at a station, a pair of sensors 144 and 146 are provided at the uppermost level of the transducer. The sensor 144 comprises a permanent magnet 148 and a reed switch 150 which is closed when the null vane 76 of an address signal device extends therebetween. Similarly, the sensor 146 comprises a permanent magnet 152 and a reed switch 154 154 which is closed when the null vane 74 of an address sensing device extends between the magnet 152 and the reed switch 154. The relative positions of the null vanes 74 and 76 and the sensors 144 and 146 are adjusted so that both reed switches 150 and 154 are closed when the stacker vehicle reaches the desired or null position with reference to the bins at the station. When the vehicle approaches a station so that the transducer 60 approaches alignment with the signal device 50, the strobe vane 72 will enter the air gap of the sensor 140 between the permanent magnet 106 and the reed switch 143 thereby causing the reed switch to close. When the strobe vane 72 is in such a position each of the address code vanes are similarly positioned with reference to their respective sensors and thus the transducer is enabled by the strobe vane to produce a parallel readout of the station address by simultaneous response of the sensors in the address readout matrix 66.

It will be now be appreciated that the address signal devices 50, 52, 54, etc., at the various stations may be read out by the transducer 50 while the stacker vehicle is either stationary at the given station or while it is moving through the given station enroute from an initial station to a destination station. The readout is substantially instantaneous and occurs only when the vehicle is in a predetermined position with reference to the given station as indicated by the strobe sensor. Thus, the readout of the station addresses while the vehicle is in its initial position and while it is moving toward its destination may be used for control of the motive power means of the vehicle to achieve the desired acceleration and speed control so that the vehicle reaches its destination in an optimum time period.

In order to utilize the station address signal devices and the transducer therefor just described, a control system responsive thereto is provided for automatically controlling the motive power means of the stacker vehicle. Such a control system will be described with reference to FIG. 8 wherein it is illustrated in block diagram form. A control system of this type is disclosed and claimed in copending US. Pat. application, Ser. No. 880,582 filed on Nov. 28, 1969 by James H. Snyder for Means for Controlling Automatically Moved Vehicle.

Referring now to FIG. 8, the automatic control system embodying the address signal device and transducer just described utilizes a logic scheme which determines the distance and direction from the stacker vehicle to its destination station and controls the direction and speed of the motive power means in accordance therewith. In general, the logic scheme comprises the generation of signals corresponding to the addresses of all stations in a prescribed sequence and comparison thereof with a signal corresponding to the current location of the stacker vehicle and comparison also with a signal corresponding to the assigned destination of the stacker vehicle. When an address signal in the sequence of all address signals coincides with the signal corresponding to the current address of the vehicle, a location signal is generated and when it coincides with the signal corresponding to the assigned destination of the vehicle a destination signal is generated. The order in which the location signal and destination signal occur is indicative of the direction of travel required of the vehicle to move toward the destination station. The interval between the occurrence of the location signal and the destination signal is a measure of, or indicative of, the distance to be traveled from the current vehicle position to the destination station. The value of this interval may be used to generate a speed control signal whereby the driving means for the vehicle may be operated at high speed when the distance to be traveled is great with the speed being reduced in desired increments as the destination station is approached. When the location signal and the destination signal coincide in time the occurrence is indicative that the vehicle has arrived at the destination station and the speed control means for the vehicle motor may be switched to a final positioning mode of operation which operates to position the vehicle at the destination station in accurate alignment with the bins.

As shown in FIG. 8, the addresses of all stations accessible to the stacker vehicle are generated in sequence in binary form by a clock pulse generator or multivibrator and a digital pulse counter 162 with a shift register which receives the output of the multivibrator and registers the count thereof in continuous manner. A signal corresponding to the current location of the stacker vehicle is generated by the transducer 60 by its coaction with the station address signal device 50 which, for example, is the station in which the vehicle is parked or through which it is moving at the time. A signal in binary form corresponding to the address of the desired destination station for the vehicle is generated by an input device 164 which may suitably take the form of a punched card which stores the desired instruction information and a card reader, not shown, which produces the input signal in binary form. To obtain a vehicle location signal, the output of the counter 162 is supplied through line 166 to one input of a count coincidence detector 168 and the address output of the transducer 60 is supplied through a line 170 to the other input of the coincidence detector 168. When the station address represented by the output of the counter 162 coincides with the address represented by the output of the transducer 60 the coincidence detector 168 will produce an output pulse on line 172 which is connected to an input of an interval circuit 174 and one input of an AND gate 176. The occurrence of the vehicle location pulse in relation to the initial count of the multivibrator pulses is indicative of the number of stations by which the stacker vehicle is removed from the initial station. The output of the counter 162 is also supplied over a line 178 to one input of a second count coincidence detector 180 and the output of the input device 164 is supplied to the other input of the coincidence detector 180. The detector 180 will produce a destination signal pulse at its output when the counts on the respective inputs coincide and this pulse is applied over a line 182 to the other input of the interval circuit 174 and the other input of the AND .gate 176. The occurrence of the destination signal pulse in relation to the initial count of the multivibrator pulses is indicative of the number of stations by which the destination station is removed from the initial station. When the multivibrator has generated a number of pulses corresponding to the total number of stations in the system'the counter 162 isfilled or reaches its upper preset limit and produces an end-of-count or reset pulse at its other output which is supplied over a line 184 to the reset input of the interval circuit 174.

in order to control the direction of the stacker vehicle a direction sensing circuit 186 is provided to detect the order of occurrence of the location signal pulse and the destination signal pulse which are applied thereto through the interval circuit 174 on lines 188 and 190, respectively. The direction sensing circuit 186 which suitably takes the form of a polarity switching circuit responds to the sequence of the input signals and producesan output of one polarity corresponding to a first sequence and an output of the opposite polarity for a second sequence. This output of the direction sensing circuit is applied over a line 192 the drivingcontrol means 194 of the stacker vehicle.

For the purpose of controlling the speed of the stacker vehicle, the distance from the current address of the vehicle to the destination station is continuously determined. For this purpose, the interval circuit 174 which receives the location signal pulse on line 172 and the destination signal pulse on line 182 is adapted in response thereto to produce a control signal on a line 196 which is applied to one input of a ripple counter 198. The control signal applied to the input of the ripple, counter from the interval circuit is effective to start andstop the counting action of the ripple counter 198 so thatthe period of counting is commensurate with the time period between the location signal pulse and the destination signal pulse. There is also provided an AND gate 200 which has one input connected through a line 202 to the output of the multivibrator 160. Another input of the AND gate 200 is connected through a line 204 to the strobe signal sensor 142 in the transducer 60. An additional input of the AND gate 200 is connected to a manual enable switch 206 which is closed to initiate automatic control of the stacker vehicle. The output of the AND gate is connected through a line 208 to the other input of the ripple counter 198. Thus, with the manual enable switch 206 closed and a strobe signal present on line 204 by reason of the vehicle being parked in or passing through a station, the AND gate 200 will apply the clock pulses from the multivibrator to the other input of the ripple counter. The ripple counter 198 commences to accumulate the input pulse count upon the occurrence of either the location signal pulse or the destination signal pulse on line 196 and the counting action is terminated upon the occurrence of the remaining one of those pulses. Where the accumulated pulse count is relatively high and indicative of a large distance to the destination station, the ripple counter 198 produces a high speed output signal on a line 210 which is connected to one input of the speed selection circuit 212. When the accumulated count in the ripple counter 198 is of a relatively low value indicative of short distance to the destination station, the ripple counter produces a low speed output signal on a line 214 which is connected to another input of the speed selection circuit 212. Similarly, when the accumulated count is at an intermediate value the ripple counter produces an intermediate speed output signal on a line 216 which is connected to a third input of the speed selection circuit 212. The speed selection circuit 212 produces an output signal on a line 218 which is connected to one input of the driving control means 194 for the stacker vehicle. The driving control means is connected with the motive power means or driving means 196 which includes the propulsion motor 42 of the stacker vehicle and regulates the energization thereof to achieve the desired direction and speed control of the vehicle. The direction and speed control signals supplied to the driving control means 194 on lines 192 and 218, respectively, are produced during each sequence of address generation by the clock pulses from multivibrator 160 and the counting thereof in the counter 162. When a complete cycle of address generation is completed, the end-of-count signal on line 184 is applied to the interval circuit 174 to reset it for a new cycle and it is also applied over a line 220 to a reset input of the ripple counter 1.98 to reset the counter for a new cycle of operation. The address generation cycle by the multivibrator 160 and counter 162 is repeated continuously and for each such cycle a location signal pulse is generatedby'the coincidence detector 168 and a destination signal pulse is produced by the coincidence detector 180. Accordingly, a direction control signal is produced by the direction sensing circuit 186 and applied to the driving control means 194 and upon the occurrence of each strobe signal by the transducer 60 the ripple counter 198 produces a speed control signal which is applied through the speed selection circuit 212 to the driving control means 194. Thus, the vehicle control signals are updated at each way station between the initial station and the destination station.

When the stacker vehicle reaches the destination station the location signal pulse from the coincidence detector 168 and the destination signal pulse from the coincidence detector 180 will occur simultaneously at the respective inputs of the AND gate 176. The AND gate 176 is responsive to the coincidence of the inputs to produce an output signal on line 222 which is connected to a fourth input of the speed selection circuit 212 and is effective to transfer control of thedriving means 196 from the driving control means 194 to a fine positioning means 224. The fine positioning means 224 suitably takes the form of a servo which receives its input signal from the null position sensors 144 and 146 of the transducer 60 over the lines 226 and 228, respectively. The fine positioning means 224 produces an output connected with the driving means 196 to control the energization thereof to position the stacker vehicle in a null position with reference to the null sensors and null vanes of the transducer and address signal device.

in the operation of the system just described the stacker vehicle 28 is to be driven from an initial station to a destination station to transfer a material unit. The destination station is selected by supplying the address thereof through the input device 164 and the system is energized for automatic control, as by the closure of the manual enable switch 206. Each of the stations along the access aisle 16 and accessible to the stacker vehicle 28 is provided with an address signal device 50, 52, 54, etc., as illustrated in FIGS. 3 and 4 in position so that the transducer 60 on the side of the stacker vehicle coacts therewith when the vehicle is either at rest in a station or is moving through a station. As previously described, each of the address signal devices is provided with vanes 70 at one or more of the predetermined positions a through h and j in the address matrix area to represent the station address in coded forrn. Each signal device'also includes a strobe vane 72 and a pair of null vanes 74 and 76.

The continuous generation of station addresses in sequence and repeated cycles thereof by the clock pulses from multivibrator 160 and the count thereof in counter 162 commences upon energization of the system. Assuming that the stacker vehicle is initially at rest in a given station, the transducer 60 coacting with the address signal device, such as device 50, supplies the address signal to the coincidence detector 168 and when the address corresponding thereto is reached by the counter 162 the coincidence detector 168 produces a location signal pulse which is applied on line 172 to the interval circuit 174 and to the AND gate 176. Similarly, when the clock pulses from the multivibrator 160 and the counter 162 reach the address corresponding to the destination address supplied by the input 164, the coincidence detector 180 produces a destination signal pulse which is applied to the interval circuit 174 and to the AND gate 176. Assuming that the vehicle was at an initial station near the load station 24 and the assigned destination station is at the remote end of the aisle, then the location signal pulse will occur before the destination signal pulse. Consequently, the direction sensing circuit 186 will produce an output signal on line 192 having a polarity corresponding to motion in a direction away from the load station 24. Since the initial station and the destination station are at a relatively great distance from each other, the interval between the location signal pulse and the destination signal pulse will be relatively great. While the vehicle is still in the initial station the transducer 60, by reason of coaction of the strobe sensor 142 with the strobe vane 72, will produce a strobe signal which is applied to the AND gate 200. The clock pulses from the multivibrator will thus be supplied through the AND gate 200 to the input of the ripple counter 198 over the relatively long interval between the location signal pulse and the destination signal pulse. Thus, a high speed signal will be developed by the ripple counter on line 210 and the speed selection circuit 212 will cause the driving control means 194 to energize the driving means 196 which includes the propulsion motor 42 to drive the stacker vehicle at high speed. When the address generation cycle is completed by the multivibrator 160 and counter 162 an end-of-count signal will be applied through lines 184 and 220 to the reset input of the interval circuit 174 and the ripple counter 198, respectively. When the next station is reached with the stacker vehicle moving therethrough at the high speed previously selected, the transducer 60 will coact with the station address signal device and produce an input to the coincidence detector 168 corresponding to the address of the station. In the same manner as just described the coincidence detector 168 will produce a location signal pulse and the coincidence detector will produce a destination signal pulse. The direction sensing circuit will respond to the sequence of the location and destination signal pulses as before and the interval circuit 174 will, together with the strobe signal from the transducer 60, cause the ripple counter 198 to produce a speed signal in accordance with the pulse count in the interval between the location signal pulse and the destination signal pulse. The high speed signal from the ripple counter 198 will persist while the vehicle is at a great distance from the destination station. However, as the vehicle continues to move through way stations toward the destination station and the distance is reduced to a predetermined amount the system will continue to operate in the manner described except that the number of pulses applied to the ripple counter in the interval between the location signal pulse and the destination signal pulse will be reduced so that the ripple counter produces an intermediate speed signal on line 216 and the speed selection circuit 212 and driving control means 194 causes the driving means 196 to be energized for an intermediate speed of operation. As the vehicle approaches the destination station within a predetermined close range, the interval between the location signal pulse generated in response to the transducer input to the coincidence detector 168 and the destination signal pulse produced by the detector 180 is relatively small and the pulse count accumulated by the ripple counter 198 is relatively small. Accordingly, the ripple counter produces a low-speed output signal on line 214 and the speed selection circuit 212 and driving control means 194 are effective to reduce the energization of the driving means 196 for low speed operation of the vehicle. As the vehicle continues to move into the destination station the location signal pulse from the coincidence detector 168 and the destination signal pulse from the coincidence detector 180 occur simultaneously and the AND gate 176 produces an output 13 signal online 22 which is applied to the speed Selection circuit 212 and transfers control of the driving means 196 from the driving control means 194 to the fine positioning means 224. In this mode of operation the null sensors 144 and 146 coact with the null vanes 76 and 74 on the address signal device at the destination station to produce control signals on lines 226 and 228 for the fine positioning means 224. The fine positioning means controls the energization of the driving means to position the vehicle with reference to the address signal means and the null vanes thereof and bring it to rest in accurate alignment with the storage bin at the destination address. After transfer of the material unit from the assigned storage bin the stacker vehicle is ready for movement to a new destination station in accordance with the instructions applied to the input 164.

Although the description of this invention has been given with respect to a particular embodiment thereof, it is not to be construed in a limiting sense. Many modifications and variations will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a storage system of the type with a large number of storage stations wherein a vehicle is caused to move from an initial station through intermediate stations to a destination station to deposit and pick up material units and having a control means for the vehicle which reads the addresses of the stations while the vehicle is enroute for controlling the motive power means of the vehicle, the improvement which comprises address means at each station with plural binary code element positions in a predetermined array and code elements disposed in said positions in accordance with the address, a transducer on said vehicle and adapted to coact with the address means at each station when the vehicle is adjacent such station, said transducer including plural address sensors disposed in an array corresponding to the code element positions in the address means, each of said sensors being operatively connectable with said control means, each of said address means including a strobe signal element, a strobe element sensor on said transducer, said strobe element sensor being operable when adjacent said strobe signal element to connect said address sensors to said control means whereby the binary code elements of a given address means are all read out simultaneously.

2. The invention as defined in claim 1 wherein said predetermined array of binary code element positions comprises plural columns and rows, said transducer and address means being adapted for alignment with each sensor in opposed relation to the corresponding code element position on said address means, said sensors being adapted to change from a first state to a second state when a code element is disposed adjacent thereto whereby said sensors will assume a state corresponding to the address of said station.

3. The invention as defined in claim 1 wherein said sensors each includes a field producing means and a field responsive means in spaced relation to each other and each of said code elements includes a passive field distorting means adapted to coact with said field producing means and cause operation of the field responsive means when a predetermined positional relationship occurs.

4. The invention as defined in claim 3 wherein said field producing means comprises amagnet and said field responsive means comprises a magnetically responsive switching means and wherein said field distorting means comprises a member of magnetic material of high permeability relative to that of air.

5. The invention as defined in claim 1 wherein each of said sensors comprises a permanent magnet and a magnetic field responsive switch with an air gap therebetween and wherein said binary code elements comprise a plate of magnetic material adapted to extend into said air gap, each of said switches being adapted to change from a first state to a second state when a plate of magnetic material is disposed in said air gap, said transducer and said address means being adapted for alignment with each sensor in opposed relation to the code elementpositions in the address means whereby said sensors will assume a state corresponding to the address of said station.

6. The invention as defined in claim 1 wherein each of said binary code elements is a magnetic plate and all of the plates in the address means are parallel to each other and to the direction of travel of said vehicle and wherein each of said sensors comprises a U-shaped body with the magnet in one leg and switching means in the other leg with an air gap therebetween, all of said sensors being oriented on said vehicle so as to straddle the respective magnetic plates of the address means.

7. A device for reading the respective addresses of a plurality of stations by a vehicle movable past said stations, said device comprising address means at each station including a support member defining plural positions in a predetermined array with a passive code element at selected positions whereby the combination of code elements identifies the address of the respective stations in code form, a transducer adapted to be mounted on the vehicle and including an active sensor corresponding to each of plural positions and being disposed in said predetermined array, each of said sensors being adapted to change from a first state to a second state when a passive code element is disposed adjacent thereto, said transducer and said address means being adapted for alignment with each sensor in opposed relation to the corresponding position on said support member whereby said sensors will assume a state corresponding to the address of said station.

8. The invention as defined in claim 7 wherein said sensors each includes a field producing means and a field responsive means in spaced relation to each other and each of said code elements includes a passive field distorting means adapted to coact with said field producing means and cause operation of the field responsive means when a predetermined positional relationship occurs.

9. The invention as defined in claim 7 wherein each of said sensors comprises a permanent magnet and a magnetic field responsive switch with an air gap therebetween and wherein said code elements comprise a plate of magnetic material adapted to extend into said air gap, each of said switches being adapted to change from a first state to a second state when a plate of magnetic material is disposed in said air gap, whereby said switches will assume a state correspond- .5 ing to the address of said station when the transducer and address means are aligned.

10. A device for reading the respective addresses of a plurality of stations by a vehicle movable past said stations, said device comprising address means at each station including an address support member defining plural positions in a predetermined array with a magnetic plate at selected positions whereby the combination of the magnetic plates identifies the address of the respective. stations in code form, said magnetic plates extending outwardly from said support plate and parallel to each other, said support plate being adapted for mounting at its respective station with said magnetic plates parallel to the direction of travel of said vehicle, a transducer adapted to be mounted on the vehicle and including a transducer support member defining plural positions in said predetermined array, a magnetic field responsive switch and a magnet with an air gap therebetween at each of said positions on said transducer support member, each of said switches being adapted to change from a first state to a second state when a magnetic plate is disposed in its air gap, said transducer and said address means being adapted for alignment with said positions on said transducer support member in opposed relation to the corresponding positions on said address support member whereby said switches will assume a state corresponding to the address of said station.

11. The invention as defined in claim wherein each of said transducers includes a U-shaped body with the permanent magnet in one leg and the reed switch in the other leg with an air gap between said legs.

12. A device for reading he respective addresses of a plurality of stations by a vehicle movable past said stations, said device comprising address means at each station including a support member defining plural positions in a predetermined array with a code element at selected positions whereby the combination of code elements identifies the address of the respective stations in code form, said array including at least one pair of positions spaced transversely of the direction of motion of the vehicle past said stations, a transducer adapted to be mounted on the vehicle including plural sensors corresponding to each of said plural positions and being disposed in an array corresponding to said predetermined array, each of said sensors comprising a field producing means and a field responsive means in spaced relation to each other and adapted to receive the corresponding code element therebetween as said vehicle moves into said station, the pair of sensors in positions corresponding to said pair of positions having a common field producing means disposed between said positions and having separate field responsive means disposed on opposite sides of said positions.

13. The invention as defined in claim 12 wherein said field producing means comprises a magnet and said field responsive means comprises magnetically responsive switching means and wherein said code element comprises a member of magnetic material of high permeability relative to that of air.

14. The invention as defined in claim 12 wherein said pair of said sensors comprises an E-shaped body of non-magnetic material, said field producing means being disposed in the center leg of said body and said field responsive means being disposed in the respective outerlegs of said bogy.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3809921 *Sep 23, 1970May 7, 1974Formby J & Co LtdPhase identifier assembly for endless conveyor control apparatus
US3815084 *Nov 19, 1971Jun 4, 1974Eaton CorpRetroreflective addressing technique
US3830379 *Feb 24, 1972Aug 20, 1974Harnischfeger CorpAutomatic warehouse crane
US3845715 *Aug 24, 1972Nov 5, 1974Oehler Wyhlen Lagertechnik AgSystem for positioning a vehicle
US3958102 *Oct 21, 1974May 18, 1976Conco Inc.Inventory taking system for an automatic warehouse
US4218616 *Mar 27, 1978Aug 19, 1980Litton Systems Inc.Automated warehouse vehicle position determining system
US5344269 *Oct 29, 1992Sep 6, 1994Banks Edward J KAutomatic retrieval system
Classifications
U.S. Classification307/116, 414/268
International ClassificationB65G47/48, B65G47/49, B65G1/04
Cooperative ClassificationB65G1/0421, B65G47/496
European ClassificationB65G1/04B4, B65G47/49B