MODULAR ROBOTIC WORK CELL

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. provisional patent application No. 60/786,818 filed on March 28, 2006, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] The present invention is directed toward robots and more particularly toward modular robotic work cells.

[0003] Conventionally, a manufacturing and/or material handling system utilizing a robot is assembled and fixed in place at a work site in a customized manner. Such a system is rigid and difficult to reconfigure and typically utilizes many customized components. In addition, such a system requires the robot to be programmed and tested at the work site, which means that skilled personnel must travel to, and spend considerable time at, the work site.

[0004] Recently, a self-contained spot welding work cell has been introduced by ABB MC of France. This work cell, which is sold in Europe under the tradename Flexicell, includes a platform to which a spot welding robot, a control cabinet, a pair of tables and a man machine interface are mounted. A Flexicell robotic work cell is transportable to a work site and may be connected with other Flexicell robotic work cells. [0005] Although the Flexicell robotic work cell simplifies system installation and facilitates system reconfiguration, improvements to the Flexicell work cell are desirable, especially with regard to transportation and interconnection. The present invention is directed to a robotic work cell having such improvements.

SUMMARY OF THE INVENTION

[0006] In accordance with the present invention, a robotic work cell to be supported on a support surface is provided. The robotic work cell includes a platform, a robot mounted to the platform and a holder for holding a work piece to be worked on by the robot. The holder is also mounted to the

platform. At least one movement-facilitation device is mounted to the platform. The at east one movement-facilitation device is operable, when actuated, to elevate the platform and facilitate the movement of the platform over the support surface.

[0007] Also provided in accordance with the present invention is a method of forming a robotic work cell to be supported on a support surface. The method includes providing a plurality of platform modules. Each platform module has at least one movement-facilitation device mounted thereto. The at east one movement-facilitation device is operable, when actuated, to elevate the platform module and facilitate the movement of the platform module over the support surface. One of the platform modules has a robot mounted thereto. The method further includes actuating the at least one movement- facilitation device in at least one of the platform modules and moving each of the platform modules that has its at least one movement-facilitation device actuated. The moving step is performed so as to place the platform modules together in alignment. The platform modules are then secured together.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: [0009] Fig. 1 is a front top perspective view of a first robotic work cell embodied in accordance with the present invention; [0010] Fig. 2 is a rear perspective view of the first robotic work cell;

[0011] Fig. 3 is a front perspective view of a portion of the first robotic work cell;

[0012] Fig. 4 is a front perspective view of two portions of the first robotic work cell;

[0013] Fig. 5 shows an enlarged view of a portion of two base modules of a second robotic work cell, the two base modules being fastened together by an attachment assembly;

[0014] Fig. 6 shows a schematic bottom view of the second robotic work cell showing movement-facilitating devices connected to an air supply network;

[0015] Fig. 7 shows a broken perspective view of a first embodiment of the attachment assembly;

[0016] Fig. 8 shows an end view of a second embodiment of the attachment assembly;

[0017] Fig. 9 shows a partially sectional view of a first embodiment of the movement-facilitating device, which is a caster assembly;

[0018] Fig. 10 shows a side view of a second embodiment of the movement-facilitating device, which is an air bearing;

[0019] Fig. 11 shows a bottom plan view of the air bearing;

[0020] Fig. 12 shows a top plan view of a portion of a base module with the air bearing mounted thereto;

[0021] Fig. 13 shows a sectional view of an air pad mounted to a base module;

[0022] Fig. 14 shows an end view of portions of two base modules adjoining each other, wherein the base modules have mating alignment structures;

[0023] Fig. 15 shows a perspective view of the alignment structures;

[0024] Fig. 16 shows a standards tree for use in manufacturing a robotic work cell; and

[0025] Fig. 17 shows a sub-tree of the standards tree shown in Fig. 16.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS [0026] It should be noted that in the detailed description that follows, identical components have the same reference numerals, regardless of whether they are shown in different embodiments of the present invention. It should also be noted that in order to clearly and concisely disclose the present invention, the drawings may not necessarily be to scale and certain features of the invention may be shown in somewhat schematic form. [0027] Referring now to Figs. 1-4, there is shown a work cell 10 embodied in accordance with the present invention. The work cell 10 is a self- contained cell or station where one or more desired operations are performed on a workpiece, such as a vehicle engine. The work cell 10 may be one component or unit of a larger processing line or operation. The work cell 10 has a modular construction and comprises at least one robot 12, at least one

work holder 14 and a control station 16, all of which are mounted to a platform 18 formed by a plurality of interconnected base modules 20. As shown in Fig. 1, the work holder 14 may be part of a conveying device 22 that moves the workpiece laterally into and out of the work cell 10. One or more tool or tool adapter holding devices 24 may also be mounted to the platform 18. A fence 26 may be also be mounted to the platform 18 so as to surround the robot 12, the conveying device 22 (including the work holder) and the tool or tool adapter holding device 24.

[0028] The robot 12 may be a six-axis industrial robot manipulator and the one or more desired operations may be one or more industrial robotic operations, such as a cutting, grinding, gluing, painting, deburring, or welding a work piece. The robot 12 generally includes an articulated arm assembly 28 that is mounted to a base 30 and includes upper and lower arms 32, 34. The lower arm 34 is connected to the base 30 by a waist 36 and an end effector 40 is mounted to the upper arm 32. The robot arm assembly 28 can be driven by servo motors about a plurality of axes to position the end effector 40 at any desired position within the operating range of the robot 12. These positions can be specified in terms of the positions of the end effector on each of the three-dimensional x, y and z axes of a robot Cartesian coordinate system (i.e., [px.py.pz ]).

[0029] The control station 16 is located outside the fence 26 and includes a robot work station 42 and a process cabinet 44. The robot work station 42 includes a monitor 46, a teach pendant (not shown) and a controller unit 48. The controller unit 48 has a housing 50 that encloses a control module and a drive module. The control module includes a robot controller, an uninterruptible power supply, Ethernet connections, connections for the teach pendant and monitor, and a safety interface. An operator panel is mounted on the exterior of the housing 50. The drive module includes a power supply, drive units of the robot 12, any additional motors, and an axis computer that regulates power feed to the servo motors. The process cabinet 44 houses a power supply and control equipment for controlling devices in the work cell 10 other than the robot 12 and for interfacing the work cell 10 to other work cells in the processing line. A status light 52 is mounted to the process cabinet 44 and extends upwardly therefrom. The status light 52 provides a visual

indication of the operating status of the work cell 10, i.e., running, not running, malfunction, etc.

[0030] The robot controller includes a central processing unit (CPU), memory and storage, such as one or more hard drives. The robot controller is connected to the robot 12, such as by a plurality of cables, including a motor power cable, a measurement signal cable and one or more communication cables. The robot controller is operable to execute control software stored in memory to control the operation of the robot 12. The control software is written in a robot user programming language (robot code), such as Karel, KRL or RAPID, all of which are based on the C programming language. In an embodiment of the present invention, the robot code is RAPID, which is used in robotic systems provided by the assignee of the present invention, ABB Inc.

[0031] The teach pendant is used to teach the robot 12 and includes a

CPU, memory, a monitor or screen for displaying information, and one or manual actuation devices, which may be a joystick or a plurality of jog switches or buttons. An operating system with a graphical user interface runs on the CPU. In one embodiment of the present invention, the operating system is Microsoft Windows CE. The teach pendant is compact in size, light in weight and is connected to the robot controller by a cable with an extended length.

[0032] Each base module 20 is substantially rectangular and includes a frame comprised of I-beams 56. One or more floor plates may be secured to the frame, or the frame may be left open, depending on the use of the base module 20. As shown in Fig. 3, a frame of a base module 20 may include a pair of parallel side I-beams 56a having their ends secured together by a pair of parallel end I-beams 56b, wherein the side I-beams 56a are longer than the end I-beams 56b. A plurality of transverse I-beams 56c may be secured between the side I-beams 56a. The transverse I-beams 56c may extend directly between the side I-beams 56a, or the transverse I-beams 56c may be secured between a side I-beam 56a and an intermediate I-beam 56d that is disposed between, and parallel to, the side I-beams 56a, such as the robot base module 20a shown in Fig.3. The I-beams 56 of a base module may be secured together by welded brackets, or other securement means. When

secured together to form a frame, the I-beams 56 define a plurality of rectangular vertical openings.

[0033] Each base module 20 is provided with at least one fork lift pocket 54 and a plurality of crane eyes 57. The fork lift pockets 54 facilitate the use of a fork lift to move a base module 20, while the crane eyes 57 acilitate the use of an overhead crane to move a base module 20. A fork lift pocket 54 may simply be an enlarged elliptical opening in the central member 58 of an I-beam 56 that is adapted to receive one or more forks of a fork lift, or a fork lift pocket 54 may further include a conduit aligned with the elliptical opening and extending between the I-beam 56 with the elliptical opening and an opposing I-beam 56. A crane eye 57 may comprise an opening in the upper flange member 60 of an I-beam 56 that is adapted to receive a hook of an overhead crane.

[0034] As best shown in Figs. 5 and 8, each I-beam 56 is composed of a metal, such as steel, and has a vertically-disposed central member 58 fixed between a pair of horizontally-disposed upper and lower flange members 60, 62. In this manner, the central member 58 and upper and lower flange members 60, 62 of a side I-beam 56a or an end I-beam 56b cooperate to define an inwardly-facing channel and an outwardly-facing channel. A plurality of mounting holes 64 extend through the central member. The mounting holes 64 include at least one inner mounting hole disposed between a pair of outer mounting holes. The mounting holes 64 may be evenly spaced apart. [0035] A manufacturing facility that produces work cells may have a plurality of different types of base modules 20 in stock from which base modules may be selected to form a work cell, such as the work cell 10. For example, a robot base module 20a, a conveyor base module 20b, a spacer base module 2Oc ₁ and a plurality of different width-extension base modules 2Od may be provided. The robot base module 20a is the largest of the base modules 20 and has first and second ends. A first floor plate 66 is secured to the frame of the robot base module 20a, about midway between the first and second ends. A second floor plate 68 is secured to the frame of the robot base module 20a at the second end. The first floor plate 66 may be secured to, and support, a robot 12; and the second floor plate 68 may be secured to, and support, a tool or tool adapter holding device 24. The conveyor base

module 20b is secured to, and supports a conveying device 22. The conveyor base module 20b is adapted for securement to the second end of a robot base module 20a and/or to the side(s) of one or more spacer base modules 20c. The spacer base module 20c is adapted for securement to the second end of a robot base module 20a, a side of a conveyor base module 20b, and/or the side(s) of one or more other spacer base modules 20c. The width- extension base modules 2Od have different lengths for different configurations of the work cell 10.

[0036] Each side of a robot base module 20a comprises a plurality of fork lift pockets 54 and a plurality of crane eyes 57. In addition, each end of a robot base module 20a comprises at least one fork lift pocket 54. Each side of a width-extension base modules 2Od comprises a plurality of fork lift pockets 54 and a plurality of crane eyes 57. In addition, each end of a width-extension base module 2Od comprises at least one fork lift pocket 54. Each side of a conveyor base module 20b and each side of a spacer base modules 20c comprise at least one fork lift pocket 54 and a plurality of crane eyes 57. [0037] In Figs. 1 and 2, the work cell 10 is shown having a conveyor base module 20b secured between the second end of a robot base module 20a and a spacer base module 20c. Of course, other configurations are possible. For example, in a work cell 70 partially shown in Fig. 5 and shown schematically in Fig. 6, a width-extension base module 2Od may be secured to a side of a robot base module 20a, an end of a conveyor base module 20b and an end of a spacer base module 20c to form a platform 71. Another configuration of a work cell may include a conveyor base module 20b secured between a pair of robot base modules 20a. In such a configuration, a pair of robots 12 may be secured to the first floor plates 66 of the robot base modules 20a, respectively. Only one control station 16 may be secured to one of the robot base modules 20a.

[0038] Referring now to Figs. 5 and 7, a pair of base modules 20, such as a robot base module 20a and a width-extension base module 2Od, are secured together by an attachment assembly 74 that comprises a connector bar 76, a lower bar support 78 and an upper bar support 80. [0039] The connector bar 76 is elongated and is composed of metal, such as steel. The connector bar 76 has a generally triangular cross-section

and includes a vertically-disposed outer surface 76a, a vertically-disposed inner surface 76b, a horizontally-disposed upper edge surface 76c, a horizontally-disposed lower edge surface 76d, an upper sloping surface 76e and a lower sloping surface 76f. The upper sloping surface 76e slopes downwardly and inwardly from the upper edge surface 76c to the inner surface 76b, while the lower sloping surface 76f slopes upwardly and inwardly from the lower edge surface 76d to the inner surface 76b. A plurality of horizontally-disposed mounting bores 84 extend through the connector bar 76, between the outer and inner surfaces 76a, 76b. The mounting bores 84 may be arranged in a pair of groups separated by a central spacing. The central spacing is sized so that innermost mounting bores 84 in the groups align with adjacent end mounting holes 64 in I-beams 56 disposed end-to-end in a pair of base modules 20 being secured together. The mounting bores 84 in each group have the same spacing as the spacing between the mounting holes 64 in the I-beams 56.

[0040] The lower bar support 78 and the upper bar support 80 are each elongated and composed of metal, such as steel. Each of the lower and upper bar supports 78, 80 has a generally right-triangular cross-section and includes an inner surface 78a, 80a, an outer surface 78b, 80b, an edge surface 78c, 80c, and a sloping surface 78d, 8Od. The upper bar support 80 further has a top surface 8Oe and the lower bar support 78 further has a bottom surface 78e. The sloping surface 8Od of the upper bar support 80 slopes downwardly and inwardly from the outer surface 80b to the inner surface 80a, while the sloping surface 78d of the lower bar support 78 slopes upwardly and inwardly from the outer surface 78b to the inner surface 78a. [0041] In order to secure together a pair of base modules 20 using the attachment assembly, the base modules 20 are placed together such that I- beams 56 (such as end I-beams 56b) of the base modules 20 are disposed end-to-end. The connector bar 76 and the lower and upper support bars 78, 80 are placed together so as to be longitudinally aligned and such that the sloping surface 8Od of the upper support bar 80 adjoins the upper sloping surface 76e of the connector bar 76 and the sloping surface 78d of the lower support bar 78 adjoins the lower sloping surface 76f of the connector bar 76. The inner surfaces 78a, 80a of the lower and upper support bars78, 80 are

disposed slightly inward from the inner surface 76b of the connector bar 76. With the connector bar 76 and the lower and upper support bars 78, 80 so positioned, the attachment assembly 74 (which now has an overall generally rectangular shape) is inserted into the outwardly-facing grooves or channels of the end-to-end I beams 56 such that the mounting bores 84 in the connector bar 76 are aligned with mounting holes 64 in the I-beams 56. Threaded bolts 88 (shown in Fig. 8) are inserted into the aligned mounting bores 84 and mounting holes 64 and then nuts 90 are threaded onto the ends of the bolts 88. The nuts 90 are then tightened, which causes the bolts 88 to move the connector bar 76 inwardly toward the central members 58 of the I- beams 56. As the connector bar 76 moves inwardly, the connector bar 76 acts as a wedge to force the lower support bar 78 to slide outwardly and downwardly along the lower sloping surface 76f of the connector bar 76 and the upper support bar 80 to slide upwardly and outwardly along the upper sloping surface 76e of the connector bar 76. The downward and upward movement of the lower and upper support bars 78, 80, respectively, moves the lower support bar 78 into firm abutment with the lower flange members 62 of the I-beams 56 and the upper support bar 80 into firm abutment with the upper flange members 60 of the I-beams 56. The nuts 90 are tightened until the inner surface 76b of the connector bar 76 is in firm abutment with the central members 58 of the l-bars 56, at which point, the lower and upper surfaces 78e, 8Oe of the lower and upper support bars 78, 80 are in firm abutment with the lower and upper flange members 62, 60 of the I-beams 56, respectively. With the attachment assembly 74 so positioned, the I-beams 56 are secured from vertical, longitudinal and inward-outward movement relative to each other.

[0042] Referring now to Fig. 8, there is shown a second attachment assembly 92 constructed in accordance with a second embodiment of the present invention. The second attachment assembly 92 functions in a manner similar to the first attachment assembly 74 to secure together a pair of base modules 20. The second attachment assembly 92 includes the connector bar 76, but instead of having the lower and upper support bars 78, 80, the second attachment assembly has lower and upper support rods 94, 96. Each of the lower and upper support rods 94, 96 is large eight sided bar

stock, i.e. each of the lower and upper support rods 94, 96 has eight sides. The connector bar 76 and the lower and upper support rods 94, 96 are placed together so as to be longitudinally aligned and such that the upper support rod 96 adjoins the upper sloping surface 76e of the connector bar 76 and the lower support rod 94 adjoins the lower sloping surface 76f of the connector bar 76. As with the first attachment assembly 74, the second attachment assembly 92 is inserted into the outwardly-facing grooves of the end-to-end I beams 56 such that the mounting bores 84 in the connector bar 76 are aligned with mounting holes 64 in the I-beams 56. Threaded bolts 88 are inserted into the aligned mounting bores 84 and mounting holes 64 and then nuts 90 are threaded onto the ends of the bolts 88. The nuts 90 are then tightened, which causes the bolts 88 to move the connector bar 76 inwardly toward the central members 58 of the I-beams 56. As the connector bar 76 moves inwardly, the connector bar 76 once again acts as a wedge. This time, however, the inwardly-moving connector bar 76 forces the lower support rod 94 to rotate outwardly and downwardly along the lower sloping surface 76f of the connector bar 76 and the upper support rod 96 to rotate upwardly and outwardly along the upper sloping surface 76e of the connector bar 76. The downward and upward movement of the lower and upper support rods 94, 96, respectively, moves the lower support rod 94 into firm abutment with the lower flange members 62 of the I-beams 56 and the upper support rod 96 into firm abutment with the upper flange members 60 of the I-beams 56. Once again, the nuts 90 are tightened until the inner surface 76b of the connector bar 76 is in firm abutment with the central members 58 of the l-bars 56, at which point, the lower and upper support bars 94, 96 are in firm abutment with the lower and upper flange members 62, 60 of the I-beams 56, respectively. With the second attachment assembly 92 so positioned, the I-beams 56 are secured from vertical, longitudinal and inward-outward movement relative to each other.

[0043] The platforms 18, 71 of the work cells 10, 70 may each be provided with a plurality of devices 100 for facilitating the movement of the work cell 10 or 70. In one embodiment, the movement-facilitating devices 100 may be retractable caster assemblies 102. Referring now to Fig. 9, there is shown a partially sectional view of a caster assembly 102. The caster

assembly 102 includes a housing 104 having a cylindrical side wall 106, a lower end wall 108 and an upper end wall 110 with vents to atmoshere. A plate 112 is disposed inside the housing 104 and defines upper and lower chambers 114, 116. The plate 112 is movable between a retracted position, wherein the plate 112 is disposed toward the upper end wall 110, and an extended position, wherein the platel 12 is disposed toward the lower end wall 108. An air spring 118 is disposed in the upper chamber 114 and is connected by an inlet tube 120 to a source of high pressure air. A coil spring 122 disposed around a lift rod 124 is positoned in the lower chamber 116. The lift rod 124 is secured to the platel 12 and extends through an opening in the lower end wall 108. A lower end of the lift rod 124 is secured to a bracket mount 128 that rotatably holds a caster 130.

[0044] When pressurized air is not supplied to the air spring 118, the air spring 118 is in a deflated condition and the coil spring 122 biases the plate 112 upward so as to be in the retracted position. When pressurized air is supplied to the air spring 118, the air spring 118 expands and moves the plate 112 downwardly against the bias of the coil spring 122 to the extended position. The movement of the plate 112 between the retracted and extended positions causes the caster 130 to move between retracted and extended positions, respectively.

[0045] A caster assembly 102 may be secured to an I-beam 56 of a base module 20 by a channel-shaped bracket 132 having a central member 132a joined between upper and lower members 132b, 132c. The central member 132a is secured to the housing 104 of the caster assembly 102 by welding or other securement means, while the upper and lower members 132b, 132c are secured to the upper and lower flange members 60, 62 of the I-beam 56, respectively, by welding, nuts and bolts, or other securement means. The caster assemblies 102 are secured to the base modules 20 such that when the casters 130 are in their retracted positions, the bottoms of the casters 130 are flush with the bottom of the platform 18 or 71. Thus, when the casters 130 are in their retracted positions, the platform 18 or 71 rests directly on a supporting surface, and when the casters 130 are in the extended position, the platform 18 or 71 , and, thus, the work cell 10, are spaced above

the supporting surface and are supported on the casters 130 to facilitate movement of the work cell 10 or 70.

[0046] In another embodiment, the movement-facilitating devices 100 may be air bearings 136. Referring now to Figs. 10 and 11 , each air bearing 136 includes a housing 138 with a lower base plate 140. The housing 138 defines at least one interior chamber. An inlet tube 142 is secured to the housing 138 and extends into the interior chamber. The inlet tube 142is connected to a source of pressurized air. A diaphragm 144 is secured around its periphery and at its center to the base plate 140 so as to form an annular air chamber. The center of the diaphragm 144 is secured to the base plate 140 by a load pad 146. A plurality of holes 148 extend through the diaphragm 144 and are disposed around the load pad 146. At least one passage extends from the interior chamber of the housing 138, through the base plate 140, into the annular air chamber.

[0047] The air bearing 136 is adapted for placement on a supporting surface with the diaphragm 144 facing downward. When pressurized air is not supplied to the interior chamber, the diaphragm 144 is in a deflated condition and the air bearing 136 is supported on the load pad 146. When pressurized air is supplied to the interior chamber, the air travels through the base plate 140 and into the annular air chamber, which expands the diaphragm 144 downward and outward and lifts the air bearing 136 off the load pad 146. Air flows through the holes 148 in the diaphragm 144 and into a space 150 between the diaphragm 144 and the supporting surface, thereby forming an air film between the diaphragm 144 and the supporting surface. This air film has a low resistance to horizontal movement, which facilitates horizontal movement of the air bearing 136 and any structure it is supporting. [0048] An air bearing 136 may be secured to an I-beam 56 of a base module 20 by an L-shaped bracket 152 having a first member 152a secured to the housing 138 of the air bearing 136 by welding or other securement means and a second member 152b secured to the central member 58 of the I-beam 56 by welding, nuts and bolts, or other securement means. The air bearings 136 are secured to the base modules 20 such that the load pads 146 are disposed flush with the bottom of the platform 18 or 71. Thus, when the air bearings 136 are not provided with pressurized air and the diaphragms 144

are deflated, the platform 18 rests on a supporting surface, and when the air bearings 136 are provided with pressurized air and the diaphragms 144 are inflated, the platform 18 or 71, and, thus, the work cell 10 or 70, are spaced above the supporting surface and are supported on the films of air generated by the air bearings 136, thereby facilitating movement of the work cell 10 or 70.

[0049] In lieu of being fixedly secured to the base modules 20, the air bearings 136 may be removably mounted to the base modules 20. For example, the housing 138 of each air bearing 136 may be secured to a square mounting plate 154 having a width slightly smaller than the width of a rectangular opening 156 between I-beams 56 of a base module 20. If necessary, the mounting plates 154 may be secured to the housings 136 of the air bearings 136 by spacers to have proper vertical positioning. An air bearing 136 secured to a mounting plate 154 is mounted to a base module 20 by aligning the width of the mounting plate with the width of a rectangular opening in the base module, inserting the air bearing 136 and mounting plate 154 into the rectangular opening 156 and then rotating the mounting plate 154 (90° or less) so that opposing corners of the mounting plate 154 are positioned under the upper flange members 60 of a pair of opposing I-beams 56 helping to form the rectangular opening 156, as shown in Fig. 12. [0050] The movement-facilitating devices 100 may be secured to each base module 20 so that each base module 20 may be supported on the devices 100 to facilitate movement of each base module individually, as is shown schematically in Fig. 6. Alternately, the movement- facilitating devices 100 may be secured to the various base modules 20 to facilitate movement of the platform 18 or 71 as a whole and not necessarily the individual base modules 20. Thus, in the work cell 70, the robot base module 20a may be provided with four devices 100, while the width-extension base module 2Od, the conveyor base module 20b and the spacer base module 20c are each only be provided with two devices 100.

[0051] In each base module 20, the inlet tubes 120 or 142 of the movement-facilitating devices 100 are connected together by an air tube network that has at least one connector and an associated valve for connecting the air tube network to a source of pressurized air and/or to one or

more air tube networks of one or more other base modules. The air tube networks may be fixed to the base modules 20, or may be removable, such as when removable air bearings 136 are used. In each base module 20, the air tubes of an air tube network may be secured to, and run along, central members 58 of the I-beams 56. Referring now to Fig. 6, the robot base module 20a may have an air tube network 160 with an H-shaped main section

161 connected to the movement-facilitating devices 100 located at the four corners of the robot base module 20a. A side branch line 162 and first and second end branch lines 164, 166 are connected to the main section. The side branch line 162 and the second end branch line 166 each contain a connector 168 and an associated valve 170, while the first end branch line 164 only contains a connector 168. The connector 168 in the side branch line

162 is adapted for connection to a connector 168 in a side branch line of an air tube network 174 of the width-extension base module 2Od, and the connector 168 in the second end branch line 166 is adapted for connection to a connector 168 in an air tube network 176 of the conveyor base module 20b. The connector 168 in the first end branch line 164 is adapted for connection to a main air line 180 with a control valve 182, which is connected to a source of pressurized air, such as a plant air system. The control valve 182 controls the supply of pressurized air being supplied to (and, if necessary, vented from) the movement-facilitating devices 100. When the robot base module 20a is not secured to the other base modules 20b, 20c, 2Od and it is desired to move the robot base module 20a individually, the valves 170 in the side branch line 162 and the second end branch line 166 are closed and pressurized air is supplied to the air tube network 160 through the connector 168 in the first end branch line 164. When the robot base module 120a is secured to the other base modules 20b, 20c, 2Od , the valves 170 in the side branch line 162 and the second end branch line 166 are opened so that pressurized air can be supplied from the air tube network 160 of the robot base module 20a to the air tube networks of the other base modules. In this manner, the movement-facilitating devices 100 of the entire platform 71 are provided with pressurized air at about the same time so as to evenly lift the platform.

[0052] In lieu of being provided with a plurality of smaller movement- facilitating devices 100, the work cell 10 or 70 may be provided with one or more larger movement-facilitating devices, such as air pads 186. The air pad(s) 186 can be narrow so as to be in the form of a beam, or the air pad(s) 186 can be enlarged so as to be in the form of an air pallet. Referring now to Fig 13, each air pad 186 is rectangular and includes an outer housing 187 having an enlarged planar support plate 188. A plurality of side walls 190 are secured to and extend downwardly from the support plate 188. The side walls 190 define a rectangular interior chamber 191 with an open bottom. An interior air box structure 192 is secured to the outer housing 187 and is disposed in the interior chamber 191. The air box structure 192 includes at least one manifold 193 in air flow communication with a plenum 194. An inlet tube 195 extends into the manifold 193 and is connected to a source of pressurized air. A thin flexible rectangular diaphragm 196 is sealingly secured to walls 197 of the plenum 194 around the periphery thereof. A plurality of holes 198 extend through the diaphragm 196 and are dispersed throughout the area of the diaphragm 196, except at the periphery thereof. [0053] The air pad 186 is adapted for placement on a supporting surface with the diaphragm 196 facing downward. When pressurized air is not supplied to the interior manifold 193, the diaphragm 196 is in a deflated condition and the air pad 186 is supported on the side walls 190 of the outer housing 187 or the walls 197 of the interior air box structure 192. When pressurized air is supplied to the manifold 193, the air travels into the plenum 194, which expands the diaphragm 196 downward and outward and lifts the air pad 186. Air flows through the holes 198 in the diaphragm 196 and into a space between the diaphragm 196 and the supporting surface, thereby forming an air film between the diaphragm 196 and the supporting surface. This air film has a low resistance to horizontal movement, which facilitates horizontal movement of the air pad 186 and any structure it is supporting. [0054] In one embodiment of the present invention, a single very large air pad 186 (in the form of an air pallet) is provided. In this embodiment, the entire assembled frame 18 or 71 of the work cell 10 or 70 is supported on, and secured to, the air pad 186. In another embodiment of the present invention, a plurality of large air pads 186 (in the form of air pallets) are

provided, one for each base unit 20. In this embodiment, each base unit 20 is supported on, and secured to, an air pad 186. In still another embodiment of the present invention, a plurality of air pads 186 (in the form of air beams) are provided for each base unit 20. In this embodiment, the air pads 186 may be disposed in the rectangular openings in the frames of the base units 20 so that ends of the walls 197 of the air box structure 192 are disposed just above the bottom of the platform 18 or 71. In a base unit 20, each air pad 186 may be secured to the frame directly (as shown in Fig. 13), or by a plate or beam secured between opposing I-beams 56, or by brackets secured to the I-beams 56, respectively.

[0055] When a work cell 10 or 70 is provided with movement-facilitating devices 100 or one or more air pads 186 and the movement-facilitating devices 100 or one or more air pads 186 are actuated to support the work cell 10 or 70 on casters or films of air, the work cell 10 or 70 may be moved using a tow motor or other moving vehicle.

[0056] The base units of the work cell 10 may be provided with alignment structures that help ensure proper alignment of the base units 20 with each other during their interconnection. More specifically, base modules 20 that are typically connected together (such as the width-extension base module 2Od and the robot base module 20a) have mating structures that connect together like puzzle pieces to ensure the two base modules 20 are properly connected together. An example of this is shown in Figs. 14 and 15. A first member 200a of an L-shaped first bar 200 is secured (such as by welding, rivets, nuts and bolts, etc.) to the underside of an upper flange member 60 of a side I-beam 56a of the width-extension base module 2Od. A second member 200b of the first bar 200 extends downwardly from the upper flange member 60 and has a plurality of spaced-apart openings 202 extending therethrough. The openings 202 each have a shape, such as a rectangle, or a circle. A first member 204a of an L-shaped second bar 204 is secured (such as by welding, rivets, nuts and bolts, etc.) to the underside of an upper flange member 60 of a side I-beam 56a of the robot base module 20a. A second member 204b of the second bar 204 extends downwardly from the upper flange member 60 and has a plurality of projections 210 extending laterally outward therefrom. The projections 210 have cross-sections that correspond

to the shapes of the openings 202 in the first bar 200 so that the projections 210 may be closely received within the openings 202. The projections 210 are positioned so as to be in alignment with the openings 202 when the width- extension base module 2Od is properly aligned with the robot base module 20a. Thus, the side of the width-extension base module 2Od can only be abutted against the side of the robot base module 20a when the projections 210 extend through the openings 202, thereby ensuring that the width- extension base module 2Od is properly aligned with the robot base module 20a.

[0057] It should be appreciated that alignment structures can also be used to connect external structures to the work cell 10 or 70. For example, external conveyor devices may be provided with alignment structures that align with alignment structures in the end I-beams 56b of the conveyor base module 20b. The alignment structures in the external conveyor devices and the conveyor base module 20b ensure that the conveying device 22 on the conveyor base module 20b is properly connected to the external conveyor devices so as to form a conveying path that extends laterally through the work cell 10 or 70.

[0058] As can be appreciated from the foregoing, the present invention provides a number of benefits.

[0059] The present invention permits a work cell (such as the work cell

10 or 70) to be fully assembled, programmed and tested at the facility of a manufacturer and then transported as a single unit to the facility of an end user customer. Since the robot 12, the work piece holder 14, the conveying device 22 and the tool or tool adapter holding device 24 are all fixed in position relative to each other in the work cell, the robot 12 does not need to be re-programmed and re-tested after the work cell has been installed at the facility of an end user customer.

[0060] A work cell embodied in accordance with the present invention can be manufactured in accordance with a standards tree 300 as shown in Figs. 16 and 17. The standards tree sets forth a base work cell configuration 302, which may simply comprise a robot base module 20a. Beneath the base work cell configuration 302 are tiers of configurations, wherein each tier represents one or more options for a work cell. A first tier of configurations

may comprise a transport work cell configuration 304, an operating station work cell 306, a material handling work cell configuration 308 and a controls work cell configuration 310. For each first tier configuration, one or more second tier configurations are provided. For example, the transport work cell configuration 304 has second tier configurations comprising a large robots configuration 312 and a conveyor 314 configuration. The large robots configuration 312 has a pair of third tier configurations, namely a single robot configuration 316 and two robot configuration 318. The large robots configuration 312 and conveyor configuration 314 represent options for the transport work cell configuration 304. If it is desired to transport a workpiece or other item using a conveyor, the transport work cell configuration 304 is selected, whereas, if it is desired to transport a workpiece or other item using one or more robots, the large robots configuration 312 is selected. If the large robots configuration 312 is selected, a decision must be made as to whether one or two robots is desired. If a single robot is desired, the single robot configuration 316 is selected, whereas if two robots are desired, the two robot configuration 318 is selected. A single robot configuration 316 may, by way of example, comprise a robot base module 2Oa ₁ a particular type of robot and a spacer base module 2Oc ₁ whereas, a two robot configuration 318 may, by way of example, comprise two robot base modules 20a, two particular types of robots and two spacer base modules 20c.

[0061] Each configuration in the standards tree 300 (such as the two robot configuration 318) has its own package of documentation for assembling the corresponding work cell. This documentation includes a part list, assembly instructions, drawings and other information to produce the work cell from standard components (e.g. robot base module 20a) and custom components. In this regard, it should be noted that standard and custom components are indicated in the standards tree 300. [0062] The standards tree 300 may be implemented in software stored in the memory of a computer and executable by a processor of the computer. The software may include a graphical user interface having a screen that displays a graphical representation of the standards tree 300 with icons for each of the configurations. Clicking on an icon may be display a drop-down

window showing the components of the configuration and providing options for the configuration.

[0063] It is to be understood that the description of the foregoing exemplary embodiment(s) is (are) intended to be only illustrative, rather than exhaustive, of the present invention. Those of ordinary skill will be able to make certain additions, deletions, and/or modifications to the embodiment(s) of the disclosed subject matter without departing from the spirit of the invention or its scope, as defined by the appended claims.