GB2222573A - Robotic palletizer - Google Patents

Description

1 - 22 5 7 3 22- ROBOTIC PALLETIZER Backqround of the Invention This

invention relates generally to palletizers and, more particularly, to robotic palletizers operable to automatically lift and place cartons onto a pallet in a predetermined pattern or arrangement.

As one of the final steps in many manufacturing operations it is necessary to load containers of manufactured products onto pallets for shipment from the manufacturing facility. In high speed, high volume, manufacturing operations, such loading or "palletizing" can be very labor- intensive if performed manually; and a variety of machines or "palletizers" have been developed for automatically performing this function.

Because substantial savings in labor costs can be realized when automatic palletizing is utilized in high speed, high volume operations, such palletizing can be economically justified despite a relatively high initial cost and demanding service requirements for each such palletizing machine. In low speed, low volume operations, however, the potential labor cost savings are far lower, and an automatic palletizer should have a simpler construction and have a relatively lower initial cost if it is to provide a significant economic advantage over manual palletizing.

Prior palletizers have utilized electronic and mechanical encoders, in combination with a computer-based control system, to keep track of the actual position of a carton as it is transported and placed onto a pallet. Although effective, the use of such encoders significantly increases the cost of such prior palletizers, requires service skills of experts and renders such palletizers economically unsuitable for use in low speed, low volume palletizing applications.

in view of the foregoing, it is a general object of the present invention to provide a new and impro-:d robotic palletizer.

it is a more specific object of the present invention to provide a new and improved robotic palletizer which can be economically manufactured and serviced and which can be advantageously utilized in low speed, low volume palletizing operations.

Summary of the Invention

Theinvention provides a robotic palletizer operable to automatically place and arrange a plurality of objects in a predetermined pattern on a pallet. The robotic palletizer includes a hand assembly adapted to releasably grasp one or more of the objects and further includes a support assembly operable to support the hand assembly for independent movement in a substantially vertical direction and also in a substantially horizontal direction. Proximity detectors, movable with the hand assembly. sense the presence and absence of accumulated objects on the pallet to control the position and elevation of the hand assembly for placing objects on the pallet.

The support assembly of the invention advantageously includes a telescoping horizontal arm comprising an elongate outer member having an associated longitudinal axis. An elongate intermediate member, having a longitudinal axis aligned substantially parallel with the longitudinal axis of the outer member, is telescopically received in the outer member and includes an elongate lower surface. An idler wheel is mounted within the intermediate member for rotation in a substantially vertical plane and extends partly below the lower surface of the intermediate member. An elongate inner member, telescopically disposed within the intermediate member and having a longitudinal axis aligned substantially parallel - 3 with the longitudinal axis of the intermediate member, engages the idler wheel. Means are provided for displacing the inner member relative to the intermediate member in a direction substantially parallel to the longitudinal axis of each so as to rotate the idler wheel and thereby cause the idler wheel to displace the intermediate member, and the inner member, relative to the outer member.

Brief Description of the Draw

The features of the present invention together with further preferred features are set forth with particularity in the appended claims. The invention, together with the objects and advantages thereof, can best be understood by reference to the following description taken in conjunction with the accompanying drawings wherein like reference numerals identify like elements, and; Figure 1 is an isometric view of a robotic palletizer embodying various features of the invention; and Figure 2 is a cross-sectional view of the robotic palletizer illustrated in Fig. 1 taken along line 2-2 thereof.

Description of the Preferred Embodiment

A robotic palletizer 10 embodying one form of the invention is illustrated in the Figures. The robotic palletizer 10 functions to receive a plurality - 4 of regularly shaped objects, such as shipping packages. cases or cartons 12. and automatically place the cartons 12 in a predetermined pattern on a shipping pallet 14.

As illustrated. the robotic palletizer 10 includes a vertical support column. or lIZII axis 16, and an extendable horizontal arm or 11Y11 axis assembly 18 mounted for bi-directional vertical movement along the lIZII axis 16. A hand or grasping assembly 20, adapted to releasably grasp at least one and preferably a plurality of the cartons 12. is mounted to an extendable end 22 of the 11Y11 axis assembly 18. The hand assembly 20 is thus supported by the lIZII axis 16 and by the 11Y11 a-xis assembly 18 for independent movement in both the vertical and horizontal directions. Preferably. the "Y" axis assembly 18 comprises a telescoping horizontal arm as shown and described in the co-pending application of Becicka. et al., entitled "Double Telescoping Arm for Robotic Palletizers and the Like". filed on September 12, 1988 under United States patent application Serial No. 242 669.

The 11Y11 axis assembly 18 is supported for vertical movement along the lIZII axis 16 by means of a carriage 24 movable along the vertical column 16. A chain 25 (Fig. 2) is attached at one end to the carriage 24 and at the other end to a counterweight 26 within the vertical column 16. The chain 25 is also reeved over a sprocket 28 located at the top of the column 16. When the sprocket 28 is turned by means of an electric motor 30. the chain is driven in one direction or: the other to cause the carriage 24 to move up or down along the vertical column 16. An adjustable limit switch 32 is provided for sensing when the carriage 24 has reached a predetermined lower limit relative to the vertical column 16.

The "Y" axis assembly 18 includes one end 34 vjhich remains -he vertical colLi.Tn horizw.itall,; stationary relative to t 16. The extendable end 22 is driven horizontally inwardly or outwardly relative to the vertical column 16 under the power of an electric drive motor 36. The hand assembly 20 includes an outer hand plate or palm 38 and a parallel inner hand plate or palm 40 which can be driven toward or away from the outer hand plate 36. The hand assembly 20 can thereby grasp a row of the cartons 12 for placement onto the pallet 14. or can release the cartons 12 onto the pallet 14. An adjustable limit switch 42 (Fig. 2) is provided for sensing when the "Y" axis assembly 18 has been extended to a predetermined limit.

The telescoping horizontal arm 18 includes an elongate outer member or box frame 19, which is of substantially rectangular cross section and has associated therewith a longitudinal axis. An elongate intermediate member or carriage 23 is telescopically received in the box frame and is aligned substantially parallel with the longitudinal axis of the box frame 19.

The telescoping horizontal arm 18 further includes an elongate inner member or hand tube 21, which is telescopically disposed within the intermediate member or carriage 23. The longitudinal axis of the hand tube 21 is aligned substantially parallel with the longitudinal axes of the carriage 23 and the box frame 19.

An idler wheel or roller 29 (Fig. 2) is mounted within the carriage 23 for rotation in a substantially vertical plane around an axle 31 oriented substantially perpendicularly to the planes formed by side walls 27 of the carriage 23. The idler wheel 29 is positioned so that a portion of the wheel extends partly below the lower surface of the carriage 23 and into contact with the bottom interior surface 17 of the box frame 19. The idler wheel 29 also extends into contact with an undersurface 15 of the hand tube 21 at a point substantially diametrically opposed to the point of contact between the idler wheel 29 and the box frame 19. The axle 31 rides in a pair of opposed vertical slots formed in the side walls 27 of the carriage 23 so as to permit limited vertical movement of the idler wheel 29 relative to the carriage 23.

The undersurface 15 of the inner member or hand tube 21 also rests on a support roller 33 mounted to the forward end of the carriage 23. In this manner, the inner member 21 is supported by the idler wheel 29 and the support roller 33 for axial extension or retraction relative to the carriage 23.

The undersurface 15 of the inner member or hand tube 21 also rests on a support roller 33 mounted to the forward end of the carriage 23. In this manner, the inner member 21 is supported by the idler wheel 29 and the support roller 33 for axial extension or retraction relative to the carriage 23. The inner member 21 is extended or retracted relative to the carriage 23 by means of a motor-driven friction or drive wheel 35 mounted to the upper end of the carriage 23 and positioned so as to engage and bear against the upper surface 13 of the inner member 21. The drive wheel 35, together with its associated drive motor 36, is mounted between a pair of bracketk:s 37 which extend along opposite sides of the carriage 23 and which are vertically movable relative thereto. Each of the brackets 37, in turn, is affixed to the carriage 23 by means of a bolt extending through the bracket 37 and into a nut-like tab extending outwardly from each side of the carriage 23. By tightening or loosening the bolts, the vertical position of the motorized drive wheel 35 can be changed relative to the carriage 23. This adjustment allows the user to make the carriage 23 and the hand tube 21 substantially parallel with the box frame 19.

The intermediate member of the carriage 23 is supported for lateral translation relative to the outer member or box frame 19. Part of this support is by means of a roller assembly 39 mounted at the rear of the carriage 23 and engaging the upper interior wall 41 of the box frame 19. The remainder of the carriage 23 is ultimately supported by the idler wheel 29. The supporting force to the front of the carriage 23 is applied upward to the idler wheel 29 at the point where it contacts the lower interior wall of the box frame 19. The vertical position of the idler wheel 29 relative to the carriage 23 is not fixed. Rather, the idler wheel 29 is permitted to float, and the upward contact force from the lower wall of box frame 19 is transmitted directly through the idler wheel 29 to the underside of the inner member 21. This force is then transmitted through the inner member 21 to the carriage 23 via the drive wheel 35, the bolts and the nut-like tabs. Accordingly, the traction between the drive wheel 35 and the inner member 21 can be reliably maintained even as the drive wheel 35 and the idler wheel 29 wear during operation.

In operation, rotation of the friction or drive wheel 35 results in lateral translation of the inner member or hand tube 21 relative to the carriage 23. Movement of the inner member 21 in one direction relative to the carriage 23 causes the idler wheel 29 to rotate. Such rotation of the idler wheel 29 causes the carriage 23 to move in the same direction relative to the outer member or box frame 19. During extension or retraction of the horizontal arm 18, the motorized drive wheel 35 is fixed relative to the carriage 23. Therefore, the inner member 21 moves relative to the carriage 23 while the carriage 23 moves in the same direction relative to the box frame 19. The inner member 21 moves at about twice the speed of the carriage 23 due to the locations of contact with the idler wheel 29 - one contacting the idler wheel 29 at the axle and the other at the outer diameter thereof.

Means are provided for ensuring that the speed of the inner member 21 relative to the carriage 23 is substantially equal to the speed of the carriage 23 relative to the box frame 19. To this end, a pair of sprockets 44 are mounted on opposite sides of the idler wheel 29 so as to be co-rotatable therewith. A f irst chain 46, having one end attached to the rear of the inner member 21, is reeved over one of the sprockets 44. The opposite end of the first chain 46 is attached to the interior of the box frame 19 at a point located rearwardly of the idler wheel 29. A second chain 48 is connected at one end to the forward end of the inner member 21, and is reeved over the other one sprocket 44. The second chain 48 is attached, at its opposite end, to the interior of the box frame 19 at a point located forwardly of the idler wheel 29. During extension or retraction of the horizontal arm 18, the chains 46 and 48 function to ensure that the lateral translation of the inner member 21 relative to the box frame 19 is substantially twice the translation of the carriage 23 relative to the box frame 19.

The robotic palletizer further includes an infeed conveyor 44. a pallet dispenser 46 in which empty pallets 14 are stored, and a pallet conveyor 48 which conveys the empty pallets 14 from the dispenser 46 to a loading position shown in Fig. 1. A user control panel 50. containing suitable control circuitry, is provided for controlling operation of the palletizer 10.

The infeed conveyor 44 functions to meter. orient and accumulate the cartons 12 prior to loading onto the pallet 14. The infeed conveyor 44 receives the cartons 12 from an upstream conveyor (not shown), such as a gravity or low back pressure conveyor. The infeed conveyor 44 includes a low-speed section 52 and a high-speed section 54 downstream of the low-speed section 52. Because of the speed differential between these high-speed and low-speed sections, the cartons 12, which have been initially conveyed onto the low-speed section 52, automatically become spaced apart as they encounter the high-speed section 54. Upon reaching the end of the high-speed section 54, the cartons 12 are stopped and accumulated. A first photodetector 56, responsive to the passage of each of the cartons 12. counts the cartons 12 as each enters the high-speed section 54 of the.conveyor 44. This information is provided to the control circuitry. As the cartons 12 pass a photodetector 58 (also responsive to the passage of each of the cartons 12) into the accumulation area of the conveyor 44, this information is. also provided to the control circuitry for determining completion of a row of the cartons 12 in the accumulation area.

The infeed conveyor 44 is configured so that a sufficient number of the cartons 12 are accumulated at one time to form one row in each layer on the loaded pallet 14. The cartons 12 can thus be accumulated in side-byside relationship as shown in Fig. 1., In the alternative, a carton turning mechanism 60, located adjacent the inlet end of the high-speed section 54, can be actuated by the control circuitry to place the cartons 12 in end-to-end relationship as they are accumulated.

The positions of the cartons 12 and the hand assembly 20 relative to the pallet 14 are sensed by proximity detector means. The proximity detector means senses for sensing the presence and absence,of the accumulated cartons 12 on the pallet 14 to control the position of the hand assembly 20 for placing the cartons 12 on the pallet 14. For example, one can use a pair of proximity detectors 62 and 64 mounted on a support 66 which extends horizontally outwardly from the hand assembly 20. In the illustrated embodiment. the first and second proximity detectors--62 and 64 each preferably comprise an infrared photodetector system including a self-contained infrared source and infrared detector. The horizontal support 66 is located such that when the hand assembly 20 is in position over the pallet 14, the support 66 extends adjacent and along side the cartons 12 in place on the pallet 14. The support 66 is also positioned to be roughly one inch (2.54 cm) above the bottom surface of the cartons 12 being carried by the hand assembly 20.

The first proximity detector 62 is located substantially at the outermost end of the support 66 and faces toward the sides of th e cartons 12 in place on the pallet 14. The second proximity detector 64 is positioned slightly outboard of the outer hand member 38 and also faces toward the sides of the cartons 12 in place on the pallet 14.

During a pallet loading operation the first and second proximity detectors 62 and 64 operate in conjunction with control means. such as suitable microprocessor based control circuitry in the control panel 50. These proximity detectors 62 and 64 function to sense the position of the hand assembly 20 relative to the cartons 12 already in place on the pallet 14. In particular. the first proximity detector 62 operates to generate a first control signal characteristic of the vertical position of the hand assembly 20. Thus, the first proximity detector 62 senses when the height of the hand assembly 20 is sufficient to provide vertical clearance between the cartons 12 already in place on the pallet 14 and the cartons 12 in the grasp of the hand assembly 20. Similarly, the second proximity detector 64 operates to generate a second control signal characteristic of the horizontal position of the hand assembly 20. Thus. the second proximity detector 64 senses when the horizontal extension of the horizontal arm 18 is sufficient to place the outermost edge of the grasped cartons 12 adjacent the innermost edge 68 of the top row of the cartons 12 already in place.

Within the control panel 50, the control circuitry operates to control the palletizer 10 in accordance with: (a) various user-generated predetermined control inputs, (b) by the inputs, or control signals. provided by the above discussed photodetectors 56, 58 and the proximity detectors 62, 64 and (c) by the various limit switches 32, 42. Preferably, the control system comprises a programmed commercially available, microprocessor-based circuit, such as the IISLC15011 processor manufactured by Allen Bradley Company as part no. 1745-LP 153. Programming of the control system involves entering various predetermined operational data, such as the number of the cartons 12 per row; the orientation of each of the cartons 12 within the row, spacing (per user requirements) between the adjacent cartons 12 within the row and the total number of the cartons 12 for a fully loaded form of the pallet 14. This predetermined operational data and the control signal information is manipulated by a computer software program. Control of the robotic palletizer 10 is thus effected in accordance with execution of the computer program instructions which utilize the predetermined operational data input by the user and the control signal information as the variable parameters. The cartons 12 are then conveyed onto the low-speed section 52 of the infeed conveyor 44. When a sufficient number of the cartons 12 have been accumulated to form one row on the pallet 14. the hand assembly 20 closes to grip the accumulated cartons 12.

With reference to the partially loaded pallet 14 as shown in Fig. 1. when the pallet 14 is initially empty. the first row of the cartons 12 is positioned on the pallet 14 by raising the lIZII axis for a predetermined time. then extending the 11Y11 axis assembly 18 until the limit switch 42 associated therewith is activated. The lIZII axis is then lowered to the position of a "home,, limit switch 32, and the hand assembly J t.

releases the cartons 12 ontc the pallet 14. Conveniently the pallet 14 is supported level with the articles to be grasp-d and lirrit switch 32 is located above the home 1 position at a distance equal to the vertical stopping distance of the hand assembly 20. After the first row of the cartons 12 is thus deposited on the pallet 14. the hand assembly 20 is withdrawn to the initial. or "home". position over the infeed conveyor 44. That is. the 11Z'I axis raises in accordance with a timer signal from the control circuitry, Limit switch 42 is also positioned and arranged to.be actuated to halt drive motor 36 and stop movement of the "Y" axis assembly in the horizontal "home" position above the infeed conveyor 44 ' The "Z" axis then lowers until the "home" limit switch 32 is actuated. When the next row of the cartons 12 has been accumulated the lIZII axis raises for a predetermined time then the 11Y" axis assembly 18 is extended until the second photodetector 64 detects the inner edge of the previously deposited first row of the cartons 12. The IZII axis is then again lowered until the "home,, limit switch 32 is actuated. The second row of the cartons 12 is then released and is deposited on the pallet 14 in close proximity to the first row. Operation in this manner continues until the first layer of the cartons 12 on the pallet 14 is completed.

To form the second layer of the cartons 12 on the pallet 14. the horizontal arm 18 is first raised along the lIZII axis 16 until the first proximity detector 62 clears the top of the first layer. Once sufficient vertical clearance over the previously deposited layer is established, the first row of the second layer is constructed by extending the 11Y11 axis assembly 18 until the limit switch 42 associated therewith is actuated, which will then lower the lIZII axis a predetermined distance. (This distance is readily adjustable by adjusting a timer in the control circuitry.) After the first row of the second layer is thus positioned and deposited. subsequent rows are constructed by extending the 11Y'I axis assembly IB until the second proximity detector 64 detects the inner edge of the cartons 12 already in place in the second layer. Operation continues in this manner until the requisite layers have been formed on the pallet 14. Once the pallet 14 is fully loaded. it is removed from the pallet conveyor 48; and a new pallet is brought into the loading position.

If it is desired to form an interlocking loading pattern on the pallet 14. the control circuitry actuates the case turner 60 so as to turn the cartons 12 in alternate rows prior to accumulation and thereby form a desired interlocking loading pattern on the pallet 14.

The robotic palletizer 10 therefore includes a number of significant commercial advantages. The position of the cartons 12 in each row on the pallet 14 is determined either by the limit switch 42 or by actuation of the first and second proximity detectors 62 and 64. It is therefore unnecessary to monito the actual position of the hand assembly 20 during each loading cycle. This eliminates the need for costly and complex encoding techniques (and associated hardware) for continuously sensing the location of the hand assembly 20. These features thus contribute to the overall economy and serviceability of the robotic palletizer 10. The structure of the robotic palletizer 10 also results in a rugged apparatus which can handle relatively heavy cartons and allows long term performance and straightforward servicing.

While a particular embodiment of the invention has been shown and described. it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore. the aim in the appended claims is to cover all such changes and modifications as fall within the true scope of the invention.

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Claims (21)

1. A robotic palletizer operable to automatically place and arrange a plurality of objects in a predetermined pattern on a pallet, comprising:a hand assembly adapted to releasably grasp one or more of the objects; a support assembly operable to support said hand assembly for independent movement in a substantially vertical and in a substantially horizontal direction; and proximity detector means movable with said hand assembly for sensing the presence and absence of accumulated objects on the pallet to control the position of said hand assembly for placing objects on the pallet.

2. A palletizer in accordance with claim 1 wherein said support assembly includes a substantially vertical column and a substantially horizontal arm supported by and vertically movable along said vertical support column.

3. A palletizer in accordance with claim 2 wherein said hand assembly is mounted to said horizontal arm for horizontal displacement relative to said vertical support column.

4. A palletizer in accordance with claim 3 wherein said horizontal arm comprises a telescopic assembly with said hand assembly mounted at one end of said horizontal arm opposite said vertical support column.

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5. A palletizer as claimed in claim 4 including a first motor operable to raise and lower the horizontal arm relative to said vertical support column and a second motor operable to extend and retract the telescopic assembly.

6. A palletizer in accordance with claim 4 or 5 wherein the telescopic assembly comprises: an elongate outer member; an elongate intermediate member telescopically received in said outer member; an idler wheel mounted for rotation_within said intermediate member; said idler wheel extending into contact with said outer member; an elongate inner member te.lescopically disposed within said intermediate member, said inner member engaging said idler wheel; and means for displacing one of said inner member intermediate member or outer member relative to another one thereof in a direction substantially parallel to the longitudinal axis of the inner member, such that the idler wheel is rotated, whereby said inner member and intermediate member are displaced relative to each other and relative to said outer member.

7. A palletizer in accordan.ce with claim 6 when dependent upon claim 5 wherein the displacing means comprises a wheel driven by said second motor, the wheel k 1 17 - being fixedly mounted relative to said intermediate member and engaging said inner member so as to extend said inner member relative to said intermediate member in response to rotation in one direction and to retract said inner member relative to said intermediate member in response to rotation in the opposite direction.

8. A palletizer in accordance with claim 7 wherein said inner member includes an upper surface engaged by said motor driven wheel and further includes a lower surface engaging said idler wheel

9. A palletizer in accordance with claim 7 or 8 wherein said telescoping assembly further includes tensioning means for adjusting the contact force between said motorized wheel and said inner member.

10. A palletizer in accordance with claim 7, 8 or 9 wherein said idler wheel is rotatable in a vertical plane and is vertically displaceable relative to said intermediate member so that contact forces between said inner member and said idler wheel are transmitted through said idler wheel to said outer member.

11. A palletizer in accordance with any of claims 7 - 10 wherein said telescoping assembly includes further means for ensuring that the speed of said inner member relative to said intermediate member is substantially equal to the 18 speed of said intermediate member relative to said outer member during extension and retraction of said telescoping horizontal arm.

12. A palletizer in accordance with claim 11, wherein said further means includes a pair of co-rotatable sprockets mounted on said intermediate member, a first chain reeved around one of said sprockets and having one end connected to said outer member to one side of said sprockets and another end connected to said inner member, and a second chain reeved over the other one of said sprockets and having one end connected to said outer member to the other side of said sprockets and another end connected to said inner member.

13. A palletizer in accordance with any preceding claim wherein said proximity detector means includes first and second detectors.

14. A palletizer in accordance with claim 13 wherein each of said f irst and second detectors comprises a photodetector system.

15. A palletizer as claimed in claim 13 or 14 wherein said first and second detectors generate signals characteristic of the vertical and horizontal positions of the hand assembly relative to objects already placed upon n 1 19 - er is provided which utilizes the the pallet and a control signa.' s in order to control vertical and horizontal movement of the hand assembly for placing further objects on the pallet in a predetermined spatial relationship to those already present.

16. A palletizer as claimed in claim 15 wherein said first and second detectors detect the presence of objects proximate thereto in horizontal or vertical directions respectively, and, to place a further object or group of objects upon the pallet, the controller causes the support assembly to move the hand from a home position, in which it grasps the further object or group of objects through a predetermined upward vertical movement; the controller then causing the support assembly to move the hand horizontally until the second detector detects the presence of an object already on the pallet; whereupon the controller causes the support assembly to move the hand vertically downwards until the f irst detector detects the presence of an object already on the pallet, whereafter the controller causes the objects to be released from the hand in said predetermined spatial relationship.

17. A palletizer as claimed in claim 16 including a first limit switch actuated when the hand is at a predetermined vertical distance from the home position and a second limit switch actuated when the hand is at a predetermined horizontal distance from the home position, said limit switches being operatively connected to the controller, and, to place a first object or group of objects upon the pallet, the controller causes the support assembly to move the hand from the home position, in which it grasps the first object or group of objects, through a predetermined upward vertical movement; the controller then causing the support assembly to move the hand horizontally until the second limit switch is actuated; whereupon the controller causes the support assembly to move the hand vertically downwards until the first limit switch is actuated; whereafter the controller causes the articles to be released from the hand assembly.

18. A palletizer as claimed in claim 17 wherein said predetermined vertical distance is equal to the vertical stopping distance of the hand assembly, and the pallet is supported level with the bottoms of the objects to be grasped.

19. A palletizer in accordance with any preceding claim when dependent upon claims 14 and 2, wherein said palletizer further includes an elongate support extending outwardly from said hand assembly in a direction substantially parallel to said horizontal arm and wherein said first and second detectors are mounted on said elongate support.

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20. A robotic palletizer in accordance with claim 19 wherein said first detector is mounted on said elongate support at a level such that the vertical stopping distance of the hand assembly is substantially equal to the vertical distance between said first proximity detector and the uppermost edge of said objects carried by said hand assembly and wherein said second proximity detector is displaced from the outermost edge of said hand assembly by a distance substantially equal to the horizontal stopping distance of said hand assembly, the vertical and horizontal stopping distance being readily adjustable for providing optimum clearance and object placement by changing time delays using said controller.

21. A palletizer substantially as described with refepETce to or as shown by the accompanying drawifigs.

Published 1990 at The Patent OiMce, State House. ft 71 Fu&h Hc)burn. London WC1R 4TP Further coples maybe obt4med from The Patent Omos. S3as Branch. St Mary Cray. Orpuigzan. Xsnt MR5 3RD, Printed by MultAplex techrUques Itd. St Mary Cray, Kenu Con. 1,57