US3612293A

US3612293A - Automatic control translation system for material stacker

Info

Publication number: US3612293A
Authority: US
Inventors: George K Ostrander
Original assignee: Air Preheater Co Inc
Current assignee: Alstom Power Inc
Priority date: 1969-12-29
Filing date: 1969-12-29
Publication date: 1971-10-12
Anticipated expiration: 1988-10-12

Abstract

A control translation system for automatically changing the drive controls of an operator driven rotatable stacker crane when the crane rotates to an orientation other than a predetermined reference orientation. The system is particularly applicable in stacker cranes which employ a ''''joystick'''' for controlling all lateral movement of the crane. The control system includes an orientation responsive switching network for translating the control of the lateral drive motors by the ''''joystick.

Description

United States Patent George K. Ostrander Inventor Angelica, N.Y.

Appl. No. 888,601

Filed Dec. 29, 1969 Patented Oct. 12, 1971 Assignee The Air Preheater Company, Inc.

Wellsville, N.Y.

AUTOMATIC CONTROL TRANSLATION SYSTEM FOR MATERIAL STACKER 9 Claims, 11 Drawing Figs.

US. Cl 212/21, 212/128, 340/267 C, 212/131, 214/164, 212/132, 200/6, 307/139 Int. Cl B66c 17/00 Field of Search 214/164;

212/10,11,21,l24,125,128,129,130132; 200/6 A; 307/139, 140, 115; 340/267 C [56] References Cited UNITED STATES PATENTS 1,614,575 1/1927 Siebs 340/267 2,391,881 1/1946 Cl 212/21 2,529,804 1 H1950 Harnischfeger 212/21 3,061,111 10/1962 Riemenschneider 212/21 3,084,805 4/1963 McKennon 212/21 3,242,272 3/1966 Smith 200/6 A Primary Examinerl-larvey C. Hornsby Attorneys-Wayne 1-1. Lang and Eldon 1-1. Luther ABSTRACT: A control translation system for automatically changing the drive controls of an operator driven rotatable stacker crane when the crane rotates to an orientation other than a predetermined reference orientation. The system is particularly applicable in stacker cranes which employ a joystick" for controlling all lateral movement of the crane. The control system includes an orientation responsive switching network for translating the control of the lateral drive motors by the joystick."

PATENTED BN1 2 BYE SHEET 2 0F 7 FIG. 4

INVENTOR. GEORGE OSTRANDER FIG. 2

PATENTEDUBHZH?! 3612.293

SHEET 30F 7 INVENTOR.

GEORGE OSTRANDER FIG 3 ATTORNEY PATENIED um 1 2 I97! SHEET 7 OF 7 ATTORNEY BACKGROUND OF THE INVENTION The present invention relates to control of stacker cranes and, more specifically, to control of stacker cranes employed for the semiautomatic transfer and storage of materials in a warehouse having a loading dock and a plurality of storage racks. More particularly, the present invention is directed to stacker cranes which are mounted on guides, such as rails, generally mounted overhead, and which are controlled by an operator who moves with the crane. The stacker cranes in the field of my invention are of the type which are rotatably mounted to permit rotation of the load supporting portion about a vertical axis.

In the warehousing system described generally above, the crane will required to operate both in areas in which the racks are located and in areas in the warehouse free of the storage racks. In the course of such operation, it is often desireable to rotate the load handling portion of the stacker crane to provide easier access to a location or more accurate operation of the crane within a particular area. While space limitations often preclude rotating the load handling portion of the crane in the area of the storage racks, this is generally not the case in the areas intermediate the storage racks and the loading dock. In the latter mentioned areas of the warehouse the crane is usually permitted a freedom of lateral motion limited only by its guide rails and the load handling portion is free to rotate as controlled by the operator. In systems such as these, horizontal linear motion is usually provided by at least a pair of motors, one controlling motion in one direction and the other controlling motion in a direction perpendicular to the first. f ten, the control of these motors is effected by means of manually positionable control members actuated by the crane operator. These control members may exist as a pair, with one controlling one of the motors and the other controlling the other motor. However, the control of the two motors will more commonly be effected by means of a single control member which is capable of controlling both of said motors. Control members of this latter type are often referred to as joysticks. With either type of arrangement, control of one motor is linked with control member positioning in a first particular plane and control of the other motor is linked with control member positioning in a plane perpendicular to the first. Such an arrangement permits an operator who is always facing in the same direction to move the joystick in a particular direction with respect to its pivot point, such as forward, and thereby effect movement of the stacker crane in that direction. This would hold true for positioning of the joystick to the left or right of its pivot point to accordingly produce movement of the stacker crane to the left or right. This type of manual control system is advantageous because the operator may generally look in a desired direction travel, move the joystick in that direction with respect to its pivot point, and thereby effect motion of the crane in the desired direction.

However, this system becomes ineffective when the operator and his drive controls rotate with the load handling portion of the crane, as is usually permitted. Because a particular positioning of the joystick always controls the same horizontal drive motor, the operator will no longer be able to effect a forward movement of the crane, as viewed by him, when he moves the joystick in a direction which is forward with respect to him and the joystick pivot. For example, if he has rotated to the right (clockwise) 90, a positioning of the joystick forward of its center point will result in movement of the crane to the operators left.

If the operator is able to mentally reorient himself for different rotational orientations of the crane and compensates accordingly in his positioning of the joystick, then no difficulty in controlling the horizontal movements of the crane will arise. However, it is seldom that an operator can consistently reorient himself and make the compensation necessary to ef fect the proper control of the cranes movements. The confusion which attends a need to control drive movements in this manner results first in a slowdown of operation and, more importantly, may result in crane movements which cause costly injury to the property and personnel. Collisions with warehouse walls, storage racks, and other elements in, or near, the area of operation may easily occur if the operator positions the joystick in a forward direction for forward'movement, for instance, and the crane suddenly darts off to the left or right.

SUMMARY OF THE INVENTION An object of my invention is the provision of a manually controlled stacker crane which is capable of rapid and accurate movements within the warehouse area of operation.

Another object is the provision of a drive control system which permits operation in a manner which is safe to equipment and personnel.

Still another object is the provision of a drive control system which will translate control functions for various rotational orientations of the stacker crane.

In accordance with the present invention, I have provided a drive control system which is responsive to the positioning of a control member in a particular direction to effect movement of the crane in said particular direction. The control system of my invention includes means for rotating the stacker crane to an orientation in any of several predetermined directions, these directions for convenience being the four directions of travel permitted by the perpendicular horizontal guide rails. The control system further includes position sensing means which are capable of determining the rotational orientation of the crane at a particular time. The system additionally includes a drive control translating system which is responsive to particular rotational orientations to switch the control functions performed by the control member. This control translating system enables movement of the crane in a direction commensurate with the positioning of said control member, regardless of crane orientation.

BRIEF DESCRIFT ION OF THE DRAWINGS FIG. 1 is a plan view of a warehouse and a rotatable stacker crane operating therein;

FIG. 2 is a partial elevational view taken along line 2-2 in FIG. 1;

FIG. 3 is a perspective view of the stacker crane showing the rotational orientation sensing elements;

FIG. 4 is an enlarged perspective view of the control cab and control panel of the stacker crane;

FIGS. 5a-5d are schematic diagrams of the rotation control and orientation sensing circuitry of the stacker crane system;

FIGS. 60 and 6b are schematic diagrams of the switch system of the joystick control; and

FIG. 7 is a schematic diagram of the control translator of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a warehousing system embodying the invention. Stacker crane 10 is designed to transport loads, such as I2, from a loading area in warehouse 14 to selected storage racks 16. Though the geometry of warehouse l4 and placement of storage racks 16 may vary from one warehousing system to another, most warehouses are rectangular and have a portion occupied by racks 16 while another portion, or portions, are substantially free of any structures. Most stacker cranes have a vertically extending mast member, seen in FIG. 3, which limits its freedom of motion when operating in the area of racks 16, but general freedom of lateral motion is allowed elsewhere.

The stacker crane is part of a trolley I8 which is supported on wheels and rolls along guide rails which are a part of bridge 20. Bridge 20 is in turn supported on wheels and rolls along a pair of guide rails 22. Guide rails 22, more clearly seen in FIG.

2, are mounted near and extend along an opposing pair of walls in warehouse 14 at an elevation somewhat above the tops of storage racks 16. This permits bridge 20 to clear the tops of racks 16 when the crane is operating in the aisles 24. A bidirectional, multiple-speed motor (or motors) 26 is drivingly connected to Wheels 28 on bridge 20. The motor 26 can be appropriately stopped by conventional electric braking which may be supplemented by a mechanical disk brake. Motor 30 seen in FIG. 3 is drivingly connected to the wheels of trolley 18. Motor 30 is a bidirectional, multiple-speed motor and can be stopped by conventional electric braking which may be supplemented by a mechanical disk brake.

The trolley guide rails on bridge are perpendicular to bridge guide rails 22. Because motors 26 and are both bidirectional, the trolley 18 with stacker crane 10 can move in any one of four mutually perpendicular directions by selected energization of one of the

motors

26 and 30. These four basic directions of travel are conveniently assigned the cardinal point values of north, south, east and west for simplicity of reference, even though warehouse 14 may not in fact be oriented in a geographical north, south direction. Thus, the coordinate system indicated at 32 will be applicable only internally of warehouse 14.

To the north and south of storage racks 16 are the open areas of warehouse 14 in which a greater freedom of movement by stacker crane 10 is permitted. In these areas there are elements which serve to define particular areas of operation. Those areas in which the greatest freedom of movement is permitted are defined by strips of

ferromagnetic material

34 and 34.

Strips

34 and 34, seen in FIGS. 1 and 2, extend horizontally along or close to the east and west walls of warehouse 14 at the north and south extremes thereof.

Strips

34 and 34' are sensed by proximity detectors such as

magnetic oscillators

36 and 36 which are affixed to bridge 20 at the elevation of strip 34. Detection of strip 34 by sensor 36 will indicate that bridge 20 and stacker crane 10 are located within the limits of strip 34.

In the areas immediately north and south of racks l6, intermediate the strips 34 and racks 16, it may be desirable to restrict the movements of stacker crane 10 because of its proximity to the storage racks 16. Presence of stacker crane 10 in these areas is determined by the abutments 38 contacting the arm 40 of switches 42 or 42' and thereby actuating said switch. Abutment 38 is located such that it extends outwardly and will actuate switch 42 or 42' mounted on bridge 20 when the bridge is passing adjacent to said abutment, but does not interfere with movement of bridge 20.

Additionally, means may be employed for indicating that crane 10 is operating among racks 16. However, these are not shown because the control system of the invention has utility principally in the aforementioned areas of greater freedom of movement.

Stacker crane 10 is further capable of rotating about a vertical axis and it is this capability, in part, which creates need for the control system of the invention. As seen in FIGS. 1 and 3, stacker crane 10 includes a downwardly extending mast 44 which is affixed to a platform 16. Mast 44 and platform 46 move and act as one. They are supported and carried by trolley 18 in a manner which allows them to rotate with respect to the trolley. The rotation is about the vertical axis of mast 44 at the center of platform 46 and is effected by a bidirectional motor 48 on trolley 18 which drivingly engages platform 46 to provide clockwise or counterclock wise rotation thereto. The load-handling portion of the crane (forks 50) and the control cab 52, are carried by mast 44 and may move up and down mast 44 by means of hoist 54 which is driven by bidirectional motor 56. It will be noted, however, that load forks 50 and control cab 52 maintain a constant rotational orientation with respect to mast 44, rotating as it rotates and remaining rotationally stationary when mast 44 is rotationally stationary. An operator 58 within control cab 52 is responsible for manually controlling some of the movements of crane 10 in a manner to be described below.

Power for the motors, the various control systems in control cab 52, and the platform 46 can be supplied through conventional parallel bus bars or other techniques (not illustrated). These bus bars can, for example, be located along the various guide rails and on trolley 18 in such locations that wiper contacts on adjacent, relatively movable components may contact them and provide power throughout the system. The power source may be a multiphase AC system which may then be converted to single phase AC or DC at any component location requiring it.

An operator 58 in control cab 52 manually directs lateral movement and rotation of stacker crane 10. Control cab 52 contains a control panel 60 at which the manually actuated controls of the system are located. These controls include means for controlling rotation of the stacker crane, such as

switches

62, 64, 66, and 68, and means for controlling the lateral movements of the crane, such as joystick 70 and joystick control unit 72 as seen in FIG. 4. Operator 58 will generally assume a position behind control panel 60 in control cab 52 considering load forks 50 to be located at the front of stacker crane 10.

The operation of joystick 70 and the circuitry of joystick control unit 72 will be discussed more thoroughly below. Suffice it to say at this point that joystick 70 is pivoted at control panel 60 and positioning it in the forward and rearward directions operates a series of control switches which conventionally serve to control forward and reverse rotation and speed of one of the

motors

26 or 30, and positioning the joystick 70 to the left and right conventionally serves to control forward and reverse rotation and speed of the other of said motors.

The crane rotation control system includes actuating switches 62, 64, 66, and 68 which, through circuitry to be discussed below, initiate rotation of mast 44 and platform 46 in either a clockwise or counterclockwise direction. The circuitry is designed to recognize four discrete rotational orientations of mast 44 and platform 46 which have a direct relationship with the coordinate system 32 of warehouse 14. These four rotational orientations are those at which forward and reverse movements of joystick 70 will parallel either the bridge guide means (rails 22) which extend in a north and south direction, or the trolley guide rails on bridge 20 which extend in an east and west direction. Rotational orientation in one of the four cardinal point directions of 32 will hereinafter be referred to by that direction which will appear as forward to operator 58 and joystick 70. For instance, if mast 44 is orientated such that the forward direction, as viewed by operator 58, is north then that orientation will be referred to as to the north."

A rotational orientation sensing system for indicating orientation in one of the four mentioned orientations is seen most clearly in FIG. 3. Four contact actuated switches 74, 76, 78, and are spaced about the periphery of platform 46 at intervals. Cam abutment 82 is affixed to trolley 18 and is positioned to contact and actuate each of switches 74, 76, 78, and 80 as they become respectively aligned with said cam. Said switches may be of the type which are actuated upon angular displacement of the contact arm from a central position; however, this embodiment employs switches which are actuated by a linear displacement of the contact arm. The location of cam abutment 32 is established to effect switch actuation when mast 44 and platform 46 are in one of the four desired orientations. This may be done either by first locating cam abutment 82 on trolley 18 and then setting the positions of the four switches accordingly. However, a more desirable and flexible arrangement is to first position the

switches

74, 76, 78, and 80 in desirable 90 spaced locations on platform 46 and then locate cam abutment 82 on trolley 18 in the position necessary to provide proper actuation of said switches. Each switch, then, will be indicative of one of the four cardinal directions and its actuation will represent orientation of crane 10 in that said direction. Alternate systems might include either a single switch and four-spaced actuating cam on platform 46. However, in the first alternative, means to determine which cam is actuating the switch would be required and the other alternative provides the problem of electrically connecting the fixed position switches with the controls of the rotating mast 44 and its control cab 52. it should also be noted that other means of orientation sensing may be employed, e.g. magnetic proximity switches, electro-optical systems, and others, however the contact actuated switch herein employed is reliable and economical.

it is desirable to maintain crane l rotationally stationary when a desired orientation has been assumed. Position locking means are provided to accomplish this. These locking means include an electromagnetically actuated linearly moving pin 84 located at the periphery of a rotatable element such as platform 46, and four pin receivers 86 affixed to trolley 18 and located at 90 intervals about the periphery of platform 46. Pin receivers 86 and pin 84 are positioned to permit receiver 86 to engage a portion of pin 84 when said pin and receiver are in rotational alignment and said pin is actuated. Pin 34, in the actuated locking position, will have one end portion retained by platform 46 and the other end portion retained by receiver 86, thereby preventing relative motion between the two components. The positioning of the four receivers 86 with respect to pin 84 is established to allow pinning at each of the four cardinal point orientations.

The circuitry employed to effect control of the rotational movements of crane 10 is seen in FIGS. Sa-Sd. HG. a depicts the circuitry which determines the cranes location within warehouse 14. This is necessary, as previously noted, in order to ensure that crane can be rotated only in those areas in which it will not contact racks 16 while rotating.

Proximity detectors

36 and 36, respectively, serve to sense crane presence in the extreme north and south zones of warehouse 14 where freedom of movement is permitted.

These detectors, when activated, serve to close the respective switches NDP (north detection proximity) and SDP (south detection proximity). Each of said switches controls energization of a relay coil PN or PS, as shown. For example, if crane R0 is located in the northern most zone of warehouse l4, detector 36 will close switch NDP, thus energizing relay PN (north unrestricted zone) to actuate relay PN contacts. Accordingly, PS relay contacts will be actuated for crane location in the southern most zone of warehouse 14. Location of crane 10 in either of the areas of restricted movement immediately north and south of racks 16 will accordingly effect closing of either switch 42 or switch 42' which accordingly energizes either relay coil ZRN or ZRS. Relays ZRN (north restricted zone) and ZRS (south restricted zone) serve to actuate their respective contacts when energized. Various other types of zone detection circuitry may be employed as needs dictate.

FIG. Sb shows the circuitry which (a) indicates rotational orientation of the crane in any one of said four cardinal point directions, (b) initiates rotation of crane 10 from one orientation to another, and (c) indicates crane orientation in any one of four 180 arcs which are rotated 90 from one another. The circuitry of HG. 5b is essentially comprised of a plurality of relay coils in series with control switches and relay contacts and having a power source applied thereacross. Relay coils V, X, Y, and Z serve an orientation indication function and are energized or deenergized by means of cam actuated

switches

76, 78, 74, and 86 respectively. Relay coils N, S, E, and W provide a command function for crane rotation to one of said four cardinal points and are energized or deenergized by means of cam actuated

switches

76, 78, 74, and 8t) respectively, in series with push button switches 62, 64, 66, and 68 respectively. Cam actuated switches 76, 78, 74, and 80 are those switches associated with platform 46 and each is a two position, two point make switch. Switch 76 is shown in the actuated state while

switches

78, 74 and 80 are in the nonactuated position. Switch actuation occurs while in contact with cam abutment 82 and is indicative of crane orientation in one of the four cardinal point directions, in this instance north.

Relay contacts N2, S2, E2, and W2 are connected in parallel across momentary contact push button switches 62, 64, 66, and 68 respectively and serve to provide current path continuity to the respective relay coils N, S, E, and W after initial energization of one of said relays and release of said pushbutton switch.

Relay coil QW is in series with normally open contact 0W2 and normally closed contacts V2, X2, and Y2, said contacts being in parallel with normally open contact Z2 This circuitry permits energization of relay QW by the closing of contact Z2 when the crane is oriented to the west. Contacts QW2, V2, X2 and Y2 permit continued energization of relay QW until the crane is rotated to one of the three other cardinal point directions.

Relay coil OS is in series with normally open contact 082 and normally closed contacts V3, Y3, and Z3, said contacts being in parallel with normally open contact X3. The energization of relay 05 will be similar to that of QW, however, it will be dependent upon crane orientation to the south.

Relay coil QE is in series with normally open contact CH2 and normally closed contacts V4, X4, and Z4, said contacts being in parallel with normally open contact Y4 and in parallel with normally open contact 0W3. This circuitry provides for energization of relay QE by the closing of contact Y4 when the crane is oriented to the east. Contacts QE2, V4, X4, and Z4 permit continued energization of relay QE until the crane is rotated to one of the three other cardinal point directions. However, closing of contact 0W3 will permit energization of relay QE for crane orientation west of the north and south cardinal point directions. Thus, relay QE may be energized for all crane orientations but those of directly north and directly south.

Relay coil QN is in series with normally open contact 0N2 and normally closed contacts X5, Y5, Z5, said contacts being in parallel with normally open contact V5 and in parallel with normally open contact Q83. Relay QN will operate in a manner similar to that of relay ZE but displaced by This will mean that relay ON may be energized for all crane orientations but those of directly east and directly west.

The basic operational procedures for controlling crane 10 provide for lateral motion of the crane only when it is oriented in one of the four cardinal point directions, thereby necessitating energization of relay ON, 05, QE, or QW only at such time as the crane is oriented in one of the four cardinal point directions. However, once a particular relay has been energized, it is desirable to maintain it energized until the crane has rotated to one of the adjacent cardinal point directions. In the event that the rotational drive system of crane l0 fails, control of lateral motion of the crane may still be effected, as later described.

FIG. 5c depicts the circuitry employed in effecting rotation of crane 10 from one cardinal point direction to another and the circuitry for controlling pinning" at said orientations. Relays CCL, and CL effect rotation of crane 10 in counterclockwise and clockwise directions respectively. Relay CCL and CL and the other relay coils of FIG. 50 are connected across an AC source. In series with the power supply is the relay contact network comprised of contacts CCL2, CL2, ZRN2, ZRSZ, PN2, and PS2. When crane 10 is in either the north or south zone of the warehouse in which greatest freedom of motion is permitted, either contact PN2 or PS2 will be closed. Normally closed contacts ZRN2 and ZRS2 will also be closed, thereby providing a current path to the rotation command relays and their control logic. lf crane 10 moves into the areas immediately north or south of racks 16, either contact ZRN2 or ZRS2 will open to prevent initiation of the rotation command function. Once the rotation command function is initiated, the rotation of crane 10 will proceed to completion even if it should inadvertently subsequently enter one of the restricted zones. This capability is obtained by means of contacts CCL2 and CL2 which close upon energization of their respective relays.

Control of relays CCL and CL is effected by a logic network which is capable of recognizing an existing crane orientation and which functions to energize that rotation command relay which will effect crane rotation through the smallest angle of rotation necessary to reach a preselected orientation. Contacts V6, Z6, Y6, and X6 are normally open. They will be closed by crane orientation in that cardinal point direction which is effective to energize their respective controlling relays. The circuit of FIG. b depicts relay V as being energized and accordingly, contact V6 is shown in the closed position, thus indicating a crane orientation to the north. Contacts W3, E3, S3, W4, S4, N3, E4, E5, N4, S5, W5, and N5 are in series, in the manner shown, with the several contacts V6, Z6, Y6 and X6. These contacts are normally open and will be closed upon energization of their respective controlling relays. When energized, they are indicative of a selected new orientation. Normally open contacts N6, S6, E6, W6, CCL3 and CL3 are connected in parallel with this logic network and provide continued energization of relay CCL and CL after the crane has begun its desired rotation and the current path through contact V6, Z6, Y6, or X6 has opened. This ensures continuity of energization of either relay CCL or CL from initiation of crane rotation until arrival at the preselected new rotational orientation.

Relay PO is in series with paralleled contacts CCL4 and CL4 and is connected across the power source and energized at such time as either of the rotation command relays CCL or CL is energized. Energization of relay PO is effective to energize the drive mechanism which withdraws pin 84 from a locking position. Energization of relay coil PI is effective to energize the drive mechanism which inserts pin 84 into a pin receiver 86 when the crane has rotated to a preselected one of the four cardinal point orientations. Relay Pl is connected in series with normally closed contacts CCLS, CL5, and limit switch 88 across the power source. Limit switch 88, like limit switch 90, is actuated by the position of pin 84. Switch 88 is normally closed in the nonactuated position to provide a current path to relay PI. Insertion of pin 84 into receiver 86 actuates switch 88 to break the current path to relay Pl. Actuation of switch 88 serves to close a circuit to electrically energize means for holding pin 84 in the inserted" position. Relay coil RML controls energization of motor 48 to effect rotation of said motor in a left-hand direction and relay RMR controls energization of motor 48 to effect rotation of said motor in a right-hand direction. Relay RML is connected in series with contacts CL6 and limit switch 90 across the power source. Relay RMR is connected in series with contacts CCL6 and second pole set of limit switch 90 across the power source. Limit switch 90 in this instance is a normally open double pole two position two point make switch and will be actuated to the closed position only when pin 84 is fully withdrawn from receiver 86. Paralleled contacts CCL7 and CL7 are connected to the power source through limit switch 90 and serve to control means for holding pin 84 in the withdrawn position.

Rotation motor 48 is shown in FIG. 5d with contacts RMR2, RMR3, RMLZ, and RML3 connected to control energization and direction of rotation thereof. Motor 48 is shown as a three phase AC motor and rotation to the right is effected by closing contacts RMR2 and RMR3; while rotation to the left is initiated and controlled by contacts RML2 and RML3.

Joystick 70 and joystick control unit 72 are commercially available as a unitary control system. Joystick 70 is pivotably mounted at or near one of its ends to allow operator 58 to freely move and position the other end, 71. The end opposite end 71 is designed to actuate switches in response to the positioning of the joystick. The pivot point is located in a first reference plane and the joystick is in a neutral control position when it is perpendicular to this first reference plane. The first reference plane generally extends in a substantially horizontal direction. In the present embodiment control panel 60 forms the first reference plane and is inclined slightly from the horizontal. The joystick control unit 72 in this embodiment is designed to effect a first general control function in response to the positioning of joystick end 71 with respect to a second plane which is perpendicular to said first plane and includes said pivot point. Control unit 72 effects a second general control function in response to the positioning of joystick end 71 with respect to a third plane which is perpendicular to said first and second planes and includes said pivot point. The second plane will, in this instance, be substantially vertical and may extend to the left and right as viewed by operator 58. The third plane, accordingly, will be substantially vertical and will extend to the front and rear. Positioning joystick end 71 forwardly and rearwardly of said second plane effects the first control function, and positioning to the left or right of said third plane effects the second control function.

In the aforementioned joystick operated control system, the first control function is that of controlling the speed and direction of rotation of one of the

motors

26 or 30 and the second control function is that of controlling the speed and direction of rotation of the other of said motors. These control functions are effected through selective application of energizing current to the control contacts of

motors

26 and 30.

Joystick control unit 72 includes two groups of switches FR and LR, seen in FIGS. 60 and 6b. The switches of groups FR and LR are actuated in a known manner by the positioning of joystick end 71. The switches of group FR are selectively actuated when joystick end 71 is positioned at the neutral position or forwardly or rearwardly thereof. Similarly, the switches of group LR are selectively actuated when joystick end 71 is positioned at the neutral position or to the left or right thereof. The number of switches in each of switch groups FR and LR is determined by the number of motor contacts to be controlled on a particular motor. In the present embodiment, both

motors

26 and 30 have six control contacts and thus both switch groups FR and LR have six switches.

In switch group FR, FIG. 6a, switch FRI is closed, as shown, only when joystick end 71 is in a neutral position relative to forward and reverse positioning of joystick 70. Switch FRZ is closed for all positions of joystick end 71 which are forward of the neutral position. These positions are diagrammatically represented as F1, F2, F3, and F4. Switch FR3 is closed for all positions of joystick end 71 which are rearward of the neutral position. These positions are diagrammatically represented as Rel, Re2, Re3, and Re4. Switch FR4 is closed for all positions of joystick end 71 which are forward of the initial forward position F1 and for all positions which are rearward of the initial reverse position Rel. Switch FRS is closed for all positions of joystick end 71 which are forward of the secondary forward position F2 and for all positions which are rearward of the secondary reverse position Re2. Switch FR6 is closed only for the extreme forward position F4 and for the extreme rearward position Re4 of joystick end 71. The output tenninals of switches F Rl-F R6 are designated 98-108 respectively.

In switch group LR, FIG. 6b,switch LR1 is closed, as shown, only when joystick end 71 is in a neutral position relative to left and right positioning of joystick 70. Switch LR2 is closed for all positions of joystick end 71 which are to the right of the neutral position. These positions are diagrammatically represented as R1, R2, R3, and R4. Switch LR3 is closed for all positions of joystick end 71 which are to the left of the neutral position. These positions are diagrammatically represented as L1, L2, L3, and L4. Switch LR4 is closed for all positions of joystick end 71 which are to the right of the initial right side position R1 and for all positions which are to the left of the initial left side position L1. Switch LRS is closed for all positions of joystick end 71 which are to the right of the secondary right side position R2 and for all positions which are to the left of the secondary left-side position L2. Switch LR6 is closed only for the extreme rightward position R4 and for the extreme leftward position L4 of joystick end 71. The output terminals of switches LR1-LR6 are designated -120 respectively.

The circuitry of FIG. 7 comprises a control translating switching network 92 which, in response to the particular rotational orientation of crane l0, enables joystick 70 to control

motors

26 and 30 in a manner providing movement of the cane generally in the direction in which the joystick is displaced from its neutral position. v

The six previously mentioned control contacts for each of

motors

26 and 30 included: a first contact S which when energized, effects coasting or braking of the motor; a second contact F which when energized effects forward motor rotation at a base speed; a third contact Re which when energized effects reversed motor rotation at the base speed; and fourth, fifth, and sixth contacts, 2, 3 and 4 respectively, which when progressively energized effect a progressive and incremental increase in motor speed while the motor is rotating in either a forward or reverse direction.

Motors

26 and 30 are the same type in this embodiment and accordingly their particular speed increments are the same. This permits positioning joystick end 71 in a particular direction with respect to its neutral position and thereby effecting combined movement of bridge 20 and trolley 18 such that the resulting motion of crane is in a direction which is substantially the same as the positioning of joystick end 71. It will be realized that the speed ranges of the two motors may differ from each other if the desired crane performance within a particular warehouse geometry so dictates. In that instance, it might be necessary for an operator to juggle the positioning of joystick 70 somewhat while moving from one location to another, but the control translating system of the invention is equally effective in either situation.

The circuitry of FIG. 7 includes a power supply 94 which provides energizing current to the control contacts of

motors

26 and 30 through switch groups FR and LR and the control translating network 92.

The current path between power supply 94 and the switches of switch groups FR and LR is depicted as being a single conductor 96 common to all of the switches in the groups. It will be understood that total or selective control of this current path to the various switches of the groups may be effected, if desired, through the use of additional control switches or separate current paths from power supply 94 to each of the switches. Conductor 97 completes the circuit between power supply 94 and the control contacts of the motors.

Control translating network 92 is a switching network comprised of the relay contacts of orientation responsive relays QN, QS, OE, and QW. One terminal of normally open relay contacts QNl-QN6 is connected to switch group FR terminals 98-108, respectively. The other terminal of contacts QNll, 0N4, 0N5, and QN6 is connected to control contacts S, 2, 3, and 4, respectively of motor 26. The other terminal of contacts 0N2 and 0N3 is connected to a terminal of normally closed relay contacts Q82 and Q53, respectively. The other terminal of contacts QS2 and Q53 is connected to a terminal of normally closed relay contacts QW2 and 0W3, respectively. The other terminal of contacts QW2 and 0W3 is connected to control contacts F and Re, respectively of motor 26.

One terminal of normally open relay contacts QN7-QN12 is connected to switch group LR terminals lll0l20, respectively. The other terminal of contacts 0N7, QNHO, QNll, and QNlZ is connected to control contacts S, 2, 3, and 4, respectively of motor 30. The other terminal of contacts QN8 and 0N9 is connected to a terminal of normally closed relay contacts Q86 and Q87, respectively. The other terminal contacts Q86 and 057 is connected to a terminal of normally closed switch contacts 0W6 and QW7, respectively. The other terminal of contacts 0W6 and QW7 is connected to control contacts F and Re, respectively of motor 30.

A terminal of normally open relay contact OS]; is connected to the junction of contacts QN3 and Q83. The other terminal of contact 052 is connected to the junction of contacts Q82 and 0W2. A terminal of normally open relay contact Q84 is connected to the junction of contacts QNZ and Q52. The other terminal of contact Q54 is connected to the junction of contacts Q53 and 0W3. A terminal of normally open relay contact QWl is connected to the junction of contacts QN3 and Q83. The other terminal of contact QWl is connected to control contact F of motor 26. A terminal of normally open relay contacts QW4 is connected to the junction of contacts QN2 and 082. The other terminal of contact QW4 is connected to control contact Re of motor 26.

A terminal of normally open relay contact Q55 is connected to the junction of 0N9 and Q57. The other terminal of contact QSS is connected to the junction of contacts Q86 and QW6. A terminal of normally open relay contact QS8 is connected to the junction of contacts 0N8 and CS6. The other terminal of contact Q88 is connected to the junction of contacts Q87 and QW7. A terminal of normally open relay contact QWS is connected to the junction of contacts QN9 and 057. The other terminal of contact QWS is connected to control contact F of motor 30. A terminal of normally open relay contact 0W8 is connected to the junction of contacts QN8 and QS6. The other terminal of contact 0W8 is connected to control contact Re of motor 30.

One terminal of normally open relay contacts QEl-QE6 is connected to switch group FR terminals 98-408, respectively. The other terminal of contacts QEll, 0E4, QES, and QE6 is connected to control contacts S, 2, 3, and 4, respectively of motor 30. The other terminal of contact 0E2 is connected to the junction of contacts QNS and Q56. The other terminal of contact QE3 is connected to the junction of contacts QN9 and 057.

One terminal of normally open relay contacts QE7-QE12 is connected to switch group LR terminals -1120, respectively. The other terminal of contacts QE7, QEl0, 01511, and QEIZ is connected to control contacts S, 2, 3, and 4, respectively of motor 26. The other terminal of contact QE8 is connected to the junction of contacts QNZ and Q82. The other terminal of contact 0E9 is connected to the junction of contacts QN3 and Q83.

in the preferred embodiment

horizontal drive motors

26 and 30 are operated in four different modes of control; a different mode for orientation of crane 10 in each of the four cardinal point directions. Operation while oriented to the north has arbitrarily been established as the reference control mode. in this mode there is a direct control between switch group FR and motor 26 and between switch group LR and motor 30. Normally open relay contacts QNl-QNlZ will be closed as shown in FIG. 7. Normally closed contacts O82, O83, O56, O87, 0W2, 0W3, QW6, and QW7 remain closed. Thus there is a direct control between the switches of groups FR and LR and the corresponding contacts of

motors

26 and 30.

For crane orientation to the south the ON relay remains actuated as discussed earlier. This maintains the QNl-QNIZ contacts closed as with the northward orientation. However, to prevent a reversal between the positioning of joystick 70 and the direction of crane movement, the current paths to the F and Re contacts of each motor are reversed. This is accomplished by normally open contacts O51, O54, Q85, and Q58 which close for southward orientation. These contacts bypass the now open contacts O82, O83, Q86, and Q87 and translate the forward and reverse control functions of switch group FR as applied to motor 26 and translate the forward and reverse control functions of switch group LR as applied to motor 30. When oriented to the south and forward crane mo- -tion is desired, forward positioning of joystick end 71 will close switch PR2. This provides a current path from power supply 94 through switch PR2, contact QNZ, contact Q84, and contact QW3 to the Re control contact of motor 26. This results in reverse rotation of the motor and accordingly provides the desired forward movement to the south.

When crane 10 is oriented to the east or west, the normally open contacts QEll-QEHZ will close and contacts QN1-QN12 will open. This enables control current from switch group FR to bypass the QNl-QN6 contacts and to be applied to the control contacts of motor 30. Likewise control current from switch group LR may bypass the QN7-QN12 contacts and be applied to the control contacts of motor 26. This switching translates the entire control function of a switch group from one motor to the other each time crane 10 rotates 90.

In the mode of operation in which crane 10 is oriented to the east, the normally closed contacts QWZ, QW3, QW6, QW7, O82, O83, Q86, and Q37 remain closed and normally open contacts QWl, W4, QWS, Qw8, O81, O54, QSS, and Q88 remain open. This provides a direct control between switch group FR and motor 30 and between switch group LR and motor 26. When oriented to the east and forward motion is desired, forward positioning of joystick end 71 will close switch FR2. This provides a current path from power supply 94 through switch FRZ, contact 0E2, contact Q86, and contact QW6 to control contact F of motor 30, thus resulting in forward motion to the east.

lf crane 10 is oriented to the west, the normally closed contacts QWZ, 0W3, QW6, and QW7 will be open and the normally open contacts QWl, QW4, QWS, and QWS will be closed, thus translating the forward and reverse control functions provided by switch groups FR and LR of

motors

30 and 26, respectively. Therefore, forward positioning of joystick end 71 when oriented to the west will result in energization of control contact Re of motor 30, thereby effecting forward movement to the west.

From the foregoing description, it can be seen that the present invention provides an improved drive control system for driver-operated, rotatable cranes. The drive control system provides automatic control translation to effect crane movement in a direction commensurate with the positioning of a control stick when the crane is oriented in any of four different rotational orientations, thus enabling operation of the crane in a safer, faster, and more efficient manner than is heretofore possible.

While I have illustrated and described a preferred embodiment of my invention, it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I, therefore, do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What I claim is:

1. In a warehousing system having an area of operation, first guide means extending horizontally lengthwise of said area in first and third opposite directions; second guide means extending horizontally crosswise of said area in second and fourth opposite directions substantially perpendicular to the first and third directions, said second guide means being movable along said first guide means in the first and third directions; a load carrier assembly including a trolley, a vertically extending mast rotatable about its vertical axis and rotatably supported by said trolley, and a control station and load handling means carried by said mast and rotating therewith, said control station including a rectangular coordinate system having its origin therein and having one axis extending in a forward and rearward direction and the other axis extending to the left and right, said load carrier assembly being movable along said second guide means in the second and fourth direction; first motor means having first and third control contacts for moving said second guide means along said first guide means in the first and third directions in response to energization of said first and third control contracts respectively; second motor means having second and fourth control contacts from moving said load carrier assembly along said second guide means in the second and fourth directions in response to energization of said second and fourth control contacts respectively; means for reversibly rotating said mast about its vertical axis; circuit means connected to said first and second motor means; first control means in said circuit means and connected to said control contacts of said first and second motor means for selective energization thereof; the improvement which comprises:

means for sensing and indicating rotational orientations of said mast and control station in said first, second, third and fourth directions, said orientations occurring at rotational positions in which the axes of the control station coordinate system extend substantially in said first, second, third and fourth directions;

manually actuable switch means in said first control means having a plurality of output terminals for providing thereat a plurality of energizing signals to said first and second motor means, said signals being responsive to and indicative of a desired direction of motion relative to said control station coordinate system; and

control translation means connected in said first control means intermediate the output terminals of said manually actuable switch means and the control contacts of said first and second motor means and responsive to said orientation indicating means for translating the application of said energizing signals to the control contacts of said first and second motor means in each of said four rotational orientations whereby resultant motion of said load carrier assembly is substantially in said desired direction of motion.

2. The apparatus of claim 1 in which said means for reversibly rotating said mast includes: a third motor having control contacts associated therewith, said motor being connected to said circuit means; and a second control in said circuit means having means for generating a control signal indicative of a selected one of said four rotational orientations, and logic means operatively connected to the control contacts of said third motor and responsive to said orientation control signal and said orientation indicating signal for effecting rotation of said mast to said selected orientation through the smallest possible angle.

3. The apparatus of claim 1 wherein said manually actuable switch means include first and second switch groups each having a plurality of switches connected with and selectively actuated by a joystick having its fulcrum at the origin of said control station coordinate system, said first switch group responding to forward and rearward positioning of said joystick to provide forward and reverse energization signals respectively, and said second switch group responding to rightward and leftward positioning of said joystick to provide right and left energization signals respectively.

4. The apparatus of claim 3 wherein said control translation means include four sets of orientation responsive circuits, each said set including at least four normally open conductive paths responding to an indication of a particular one of said four rotational orientations to provide circuit continuity between the output terminals of said switch groups and the corresponding control contacts of said first and second motor means required to effect motion of said load carrier assembly substantially in said desired direction.

5. The apparatus of claim 4 wherein said first and second motor means each have an equal number of control contacts in addition to said first and third and second and fourth control contacts for incrementally controlling the speed of said motors in response to energization thereof and said first and second switch groups each have an equal number of joystick actuated switches said number being equal to the number of first and second motor means control contacts and said switches being responsive to the positioning of said joystick to provide directional control energization signals and speed control energization signals.

6. The apparatus of claim 5 wherein the speed control switches in a said switch group are sequentially actuated in response to the incremental positioning of said joystick away from the coordinate system origin in either direction of control of said switch group.

7. The apparatus of claim 6 wherein said orientation sensing and indicating means include four switches angularly disposed from one another about the vertical axis of said mast and a switch actuator situated to actuate a different one of said four switches for each 90 of mast rotation, said switch actuation serving to provide a signal indicative of the rotational orientation of said mast and control station.

8. The apparatus of claim 7 wherein said four orientation sensing switches are contact actuated and are positioned on having means for generating a control signal indicative of a selected one of said four rotational orientations, and logic means operatively connected to the control contacts of said third motor and responsive to said orientation control signal and said orientation indicating signal for effecting rotation of said mast to said selected orientation through the smallest possible angle.

Claims

1. In a warehousing system having an area of operation, first guide means extending horizontally lengthwise of said area in first and third opposite directions; second guide means extending horizontally crosswise of said area in second and fourth opposite directions substantially perpendicular to the first and third directions, said second guide means being movable along said first guide means in the first and third directions; a load carrier assembly including a trolley, a vertically extending mast rotatable about its vertical axis and rotatably supported by said trolley, and a control station and load handling means carried by said mast and rotating therewith, said control station including a rectangular coordinate system having its origin therein and having one axis extending in a forward and rearward direction and the other axis extending to the left and right, said load carrier assembly being movable along said second guide means in the second and fourth direction; first motor means having first and third control contacts for moving said second guide means along said first guide means in the first and third directions in response to energization of said first and third control contracts respectively; second motor means having second and fourth control contacts from moving said load carrier assembly along said second guide means in the second and fourth directions in response to energization of said second and fourth control contacts respectively; means for reversibly rotating said mast about its vertical axis; circuit means connected to said first and seconD motor means; first control means in said circuit means and connected to said control contacts of said first and second motor means for selective energization thereof; the improvement which comprises: means for sensing and indicating rotational orientations of said mast and control station in said first, second, third and fourth directions, said orientations occurring at rotational positions in which the axes of the control station coordinate system extend substantially in said first, second, third and fourth directions; manually actuable switch means in said first control means having a plurality of output terminals for providing thereat a plurality of energizing signals to said first and second motor means, said signals being responsive to and indicative of a desired direction of motion relative to said control station coordinate system; and control translation means connected in said first control means intermediate the output terminals of said manually actuable switch means and the control contacts of said first and second motor means and responsive to said orientation indicating means for translating the application of said energizing signals to the control contacts of said first and second motor means in each of said four rotational orientations whereby resultant motion of said load carrier assembly is substantially in said desired direction of motion.

7. The apparatus of claim 6 wherein said orientation sensing and indicating means include four switches angularly disposed 90* from one another about the vertical axis of said mast and a switch actuator situated to actuate a different one of said four switches for each 90* of mast rotation, said switch actuation serving to provide a signal indicative of the rotational orientation of said mast and control station.

8. The apparatus of claim 7 wherein said four orientation sensing switches are contact actuated and are positioned on said mast to rotate therewith; and said switch actuator is a cam abutment fixedly positioned on said trolley to contact each of said orientation sensing switches when in rotational alignment therewith.

9. The apparatus of claim 8 in which said means for reversibly rotating said mast includes: a third motor having control contacts associated therewith, said motor being connected to said circuit means; and a second control in said circuit means having means for generating a control signal indicative of a selected one of said four rotational orientations, and logic means operatively connected to the control contacts of said third motor and responsive to said orientation control signal and said orientation indicating signal for effecting rotation of said mast to said selected orientation through the smallest possible angle.