Abstract:
Disclosed is a mobile robotic arm workcell. A robotic arm is mounted on a superstructure that carries all the equipment associated with the workcell&#39;s task. Thus, the workcell is self-contained needing only power. The workcell may be moved by activating air bearings that are pressurized by an air compressor that is also mounted on the superstructure. Power is received via power contacts that engage a power rail. Guidance is provided a guide system. The guide system may include guide rails engaged by guide carriages. Propulsion is provided by a drive system that may engage the guide system or the factory floor.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims priority to U.S. provisional application Ser. No. 61/240,702, filed Sep. 9, 2009, entitled “Multi-Directional Mobile Robotic Cell,” which application is specifically incorporated herein by reference for all that it discloses and teaches. 
    
    
     BACKGROUND OF THE INVENTION 
     Industrial robots may be used to perform repetitive tasks such as the welding of component parts together, cutting, routing, grinding, and polishing. Typically, the robot always repeats a specific preprogrammed task. The products which are usually worked on by the robot may have a specific support structure, or jig, that support the product at a precise location in relation to the robot. In another application, industrial robots are used to position products at a precise location so that they may be worked on by another robotic device. 
     A robotic arm is a robot manipulator with functions that have been compared to a human arm. Joints of a robotic arm may allow rotational motion (such as in an articulated robot) or translational (linear) displacement. The joints of the robotic arm can be considered to form a kinematic chain. Robots and robotic arms are used, for example, in automotive assembly lines. 
     Robotic arms may be categorized by their degrees of freedom. This number typically refers to the number of single-axis rotational joints in the arm. A higher number indicates an increased flexibility in positioning a tool. Modern robotic arms typically achieve more than six degrees of freedom. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention may therefore comprise a mobile self-contained robotic workcell, comprising: a multi-degree of freedom robot arm; a gantry supporting said robot arm; an air bearing that selectively lifts said gantry off of a supporting surface for low-friction movement; a first drive system that engages a first drive surface while said gantry is lifted off of said supporting surface by said air bearing to propel said gantry in a first direction; a second drive system that engages a second drive surface while said gantry is lifted off of said supporting surface by said air bearing to propel said gantry in a second direction; a first guide carriage that engages a first guide track, the first guide carriage limiting said gantry to movement in said first direction. 
     An embodiment of the invention may therefore further comprise a mobile self-contained robotic arm workcell, comprising: a superstructure; a multi-degree of freedom robotic arm supported by said superstructure; at least one air bearing, the at least one air bearing selectively lifting said superstructure from a position resting on a support surface to an elevated position, the elevated position allowing for low friction movement of said superstructure across said support surface; a guide carriage that engages a first guide rail that directs a first movement of said superstructure while said superstructure is moved in said elevated position. 
     An embodiment of the invention may therefore further comprise a robotic arm workcell, comprising: superstructure means for supporting a multi-degree of freedom robotic arm; air bearing means for selectively lifting said superstructure from a position resting on a support surface to an elevated position, the elevated position allowing for low friction movement of said superstructure across said support surface; drive means for propelling said superstructure across said support surface in at least a first direction and a second direction; guide means for limiting a direction of travel of said superstructure while being propelled across said support surface to one of said first direction and said second direction at a time. 
     An embodiment of the invention may therefore further comprise a method of moving a robotic arm workcell, comprising: activating an air compressor contained on the workcell that supplies air to an air bearing, the air bearing lifting the workcell from a position resting on a support surface to an elevated position, the elevated position allowing for low friction movement of said workcell across said support surface; engaging a first guide carriage to a first guide rail to limit a movement of said workcell across said support surface to a first direction; engaging a first drive system to propel said workcell across said support surface in said first direction; engaging a second guide carriage to a second guide rail to limit said movement of said workcell across said support surface to a second direction; and, engaging a second drive system to propel said workcell across said support surface in said second direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view from above of a mobile self-contained robotic workcell. 
         FIG. 1A  is a perspective view from below of a mobile self-contained robotic workcell. 
         FIG. 2  is a perspective view from below of a mobile self-contained robotic workcell engaged with a first guide rail and a first power rail. 
         FIG. 3  is a perspective view from below of a mobile self-contained robotic workcell engaged with a second guide rail and a second power rail as the air bearings pass through a gap in the first guide rail. 
         FIG. 4  is a perspective view of a factory floor showing a first layout of guide and power rails. 
         FIG. 5  is a perspective view of a factory floor showing a looped track. 
         FIG. 6  is a perspective view of a factory floor showing a switchyard track. 
         FIG. 7  is a perspective view of a factory floor showing a multi-bay loop track. 
         FIG. 8  is a block diagram of a computer system. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is a perspective view from above of a mobile self-contained robotic workcell.  FIG. 1A  is a perspective view from below of a mobile self-contained robotic workcell. In  FIGS. 1 and 1A , workcell  100  comprises gantry  110 , robotic arm  120 , robotic arm  121 , air bearing  130 , air bearing  131 , air bearing  132 , air bearing  133 , air compressor  141 , cabinet  142 , cabinet  143 , dust collector  144 , computer display  145 , drive carriage  150 , drive carriage  151 , drive carriage  152 , drive carriage  160 , drive carriage  161 , and power contact  170 . 
     Robotic arms  120 - 121  are attached to gantry  110 . Robotic arms  120 - 121  may be engaged with gantry  110  via a track or channel so that they may move along the length of gantry  110 . In an embodiment, robotic arm  120  and robotic arm  121  are both on the same side of gantry  110 . Robotic arm  120  is hung from a track that comprises a top portion of gantry  110 . Robotic arm  121  sits on a track that comprises a bottom portion of gantry  110 . Thus, because robotic arm  120  and robotic arm  121  are on different tracks, they may pass by each other even though they are on the same side of gantry  110 . 
     In  FIGS. 1 and 1A , air compressor  141 , cabinet  142 , cabinet  143 , dust collector  144 , and computer display  145  are also attached to gantry  110 . Air compressor  141 , cabinet  142 , cabinet  143 , dust collector  144 , and computer display  145  are intended to be examples of equipment that may be attached to, and thus moved with, gantry  110 . 
     Other examples of equipment that may be attached to, and thus moved with, gantry  110  include, but are not limited to, welding power supplies, welding gas bottles, welding gas mixers, gas bottles, tool racks, welding wire containers, fume filtration equipment, dust filtration equipment, vision sensor systems, computers, additional air compressors, hydraulic power units, and hydraulic pumps. This list is not intended to be exhaustive. Any equipment or supplies to be used in support of the operations performed by robotic arm  120  or  121  may be attached to, and thus moved by, gantry  110 . 
     Gantry  110  is any suitable superstructure or supporting apparatus with at least one robotic arm  120 - 121  attached that also carries support equipment (such as air compressor  141  and/or dust collector  144 ) used in support of the operations performed by robotic arm  120  or  121 . Gantry  110  is also capable of being lifted with attached air bearings  130 - 133  for low friction movement across a supporting surface, such as a factory floor. Air bearings  130 - 133  may be supplied air from air compressor  141  to lift gantry (and all attached equipment) for low friction movement. 
     Air bearings  130 - 133  (a.k.a., air casters) support loads on a cushion of air like an air hockey puck on an air hockey table. Air bearings may use a flexible diaphragm beneath the load support surface. Compressed air is pumped into the diaphragm and passes through holes in the diaphragm holes and into a plenum beneath, thereby raising the supported load off the floor. Air that is forced out between the diaphragm and the floor forms a thin lubricating air film that allows for low friction movement of the supported load (e.g., workcell  100 ). Since the diaphragm is flexible, it can deflect as it encounters obstacles, or fill out as it passes over depressions in the surface. 
     In an embodiment, air bearings  130 - 133  may selectively lift gantry  110  for low-friction movement across a factory floor. One or more of drive carriages  150 - 152  may engage a drive surface while said gantry is lifted. One or more of drive carriages  150 - 152  may propel gantry  110  in a first direction. To move gantry  110  in a second direction (e.g., a direction substantially perpendicular to the first direction), one or more of drive carriages  160 - 161  may engage a different part of the drive surface to propel gantry  110  in the second direction. This is illustrated in  FIG. 1A  with drive carriages  160 - 161  and  150 - 152  being orientated at approximately 90° to each other. Drive carriages  150 - 152  and  160 - 161  may be or include, or be steered by, guide carriages that engage guide rails or otherwise provide a guide system. 
       FIG. 2  is a perspective view from below of a mobile self-contained robotic workcell engaged with a first guide rail and a first power rail. In  FIG. 2 , drive carriages  150 - 152  are shown engaged with guide rail  180 . Power contact  170  is shown engaged with power rail  190 . 
     In an embodiment, one or more of drive carriages  150 - 152  engage a guide rail  180 . When one or more of drive carriages  150 - 152  is engaged with guide rail  180 , gantry  110  is limited to movement along guide rail  180 . Typically, guide rail  180  will be fixed in relation to the floor. Guide rail  180  is shown in  FIG. 2  as being straight. However, guide rail  180  may be curved or have other shapes. 
     Power contact  170  engages power rail  190 . When power contact  170  is engaged with power rail  190 , the equipment of workcell  100  (such as compressor  141  and drive carriages  150 - 152 ) may be powered through power rail  190 . Typically, power rail  190  is fixed in relation to guide rail  180  so that the equipment of workcell  100  may be powered through power rail  190  while workcell  100  is moving along guide rail  180 . 
       FIG. 3  is a perspective view from below of a mobile self-contained robotic workcell engaged with a second guide rail and a second power rail as the air bearings pass through a gap in the first guide rail. In  FIG. 3 , drive carriages  160  and  161  are shown engaged with guide rail  182 . Power contact  170  is shown engaged with power rail  191 . It should be understood that guide rail  182  is oriented at substantially a perpendicular angle to guide rails  180  and  181 . Likewise, power rail  191  is oriented at substantially a perpendicular angle to power rail  190 . 
     In an embodiment, one or more of drive carriages  160  and  161  engage guide rail  182 . When one or more of drive carriages  160  and/or  161  is engaged with guide rail  182 , gantry  110  is limited to movement along guide rail  182 . Typically, guide rail  182  will be fixed in relation to the floor. Guide rail  182  is shown in  FIG. 3  as being straight. However, guide rail  182  may be curved or have other shapes. 
     In an embodiment, guide rails  180 - 182  may have gaps to allow air bearings  130 - 133  to cross the alignment of a guide rail  180 - 182  without interference. In  FIG. 3 , this is shown by a gap between guide rail  180  and guide rail  181  with air bearing  131  disposed in that gap. Guide rail  181  is substantially in line with guide rail  180 . Thus, guide rail  181  may be thought of as an extension of guide rail  180 . In an embodiment, the number of, and position of, drive carriages  160 - 162  is selected such that at least two of drive carriages  160 - 162  are always engaged with guide rail  180 , guide rail  181 , or both, when gantry  110  is moving in the direction controlled by guide rails  180  and  181 . 
     Power contact  170  engages power rail  191 . When power contact  170  is engaged with power rail  191 , the equipment of workcell  100  (such as compressor  141  and drive carriages  160 - 161 ) may be powered through power rail  191 . Typically, power rail  191  is fixed in relation to guide rail  182  so that the equipment of workcell  100  may be powered through power rail  191  while workcell  100  is moving in the direction of guide rail  182 . 
       FIG. 4  is a perspective view of a factory floor showing a first layout of guide and power rails. The layout shown in  FIG. 4  corresponds to the guide rail layout shown in  FIGS. 2 and 3 . 
     In  FIG. 4 , several workcells  100  are shown. These workcells  100  are guided by guide rails  180  and  181  to move in a first direction. The workcells  100  are also guided to move in a second direction by guide rail  182 . The second direction appears to be substantially perpendicular to the first direction. 
     The factory shown in  FIG. 4  has several long workbays  420  defined by columns  410 . Disposed within workbays  420  are work pieces  430 . The orientation of guide rails  180  and  181  allow workcells  100  to move along the length of workbays  420  and thus operate on work pieces  430 . The orientation of guide rail  182  allows workcells  100  to move between workbays  420  and/or work pieces  430 . The length of workcells  100  is selected such that workcell  100  may pass between the columns  410  of the factory to move between work bays  420 . Note the gaps between guide rail  180  and guide rail  181 , and guide rail  181  and guide rail  182  that allow air bearings  130 - 133  to move along guide rail  182  without interference from rails running the length of the workbays  420 . 
     Workcell  100  may be moved as follows: Air compressor  141  contained on workcell  100  may supply air to air bearings  130 - 133 . This allows air bearings  130 - 133  to lift workcell  100  from a position resting on the floor to an elevated position. This elevated position allows for low friction movement of workcell  100  across the floor. Drive carriages  150 - 152 , or a separate guide carriage, is engaged with guide rail  180  to limit the movement of workcell  100  across the floor to a first direction. One or more of drive carriages  150 - 152  are engaged to propel workcell  100  across the floor in the first direction. To move workcell  100  in a different direction, drive carriages  160 - 161 , or a separate guide carriage is engaged, with a guide rail  182  to limit the movement of workcell  100  across the floor to the second direction. One or more of drive carriages  160 - 161  are engaged to propel workcell  100  across the floor in the second direction. As workcell  100  moves along guide rails  180 - 182 , power contact  170  may engage power rails  190 - 191  (and additional power rails, as needed) to at least power air compressor  141  which keeps air bearings  130 - 133  activated. 
     When workcell  100  has reached its desired position (e.g., a new workbay  420 , or work piece  430 ) in the second direction, drive carriages  150 - 152 , or a separate guide carriage, may be engaged with another guide rail at the new position to limit the movement of workcell  100  across the floor to the first direction. One or more of drive carriages  150 - 152  may then be engaged to propel workcell  100  along the new workbay  420 , or work piece  430 . In addition, a new power rail may be engaged to receive power for compressor  141  during the movement and operation of workcell  100  along the new workbay  420 , or work piece  430 . When workcell  100  reaches a desired position along the new workbay  420 , or work piece  430 , air bearings  130 - 133  may be deactivated to lower workcell  100  to a position resting on the floor. This resting position provides a stable platform for the operation of workcell  100 . Once resting, one or more of robotic arms  120 - 121  may be activated to operate on a work piece  430 . 
     In  FIG. 4 , the work pieces are shown as wind turbine blades. It should be understood, however, that this is only an example and that other types of work pieces  430  are envisioned. Likewise, the workbays  420  of the factory shown in  FIG. 4  are long in relation to their width. This is also only an example and other types and geometries of workbays and work pieces are envisioned. 
       FIG. 5  is a perspective view of a factory floor showing a looped track. As discussed previously, guide rails  180 - 182  may have non-straight shapes.  FIG. 5  illustrates an example of a non-straight shape. As can be seen from  FIG. 5 , workcell  100  may be guided within the confines of columns  410  in a loop that encompasses multiple work pieces  430 . 
       FIG. 6  is a perspective view of a factory floor showing a switchyard track. In  FIG. 6 , workcell  100  is gradually guided from a first direction to a second direction at the end of a workbay  420 . A rail switching device (not shown) may then be repositioned to guide workcell  100  into a different workbay  420  and/or work piece  430 .  FIG. 7  is a perspective view of a factory floor showing a multi-bay loop track. 
     In  FIGS. 2-4 , workcell  100  is shown being guided by guide rails  180 - 182 . It should be understood that workcell  100  may be guided by other guidance means. For example, the workcell may be guided by overhead rails. These rails may also supply power to workcell  100 . 
     In an embodiment, workcell  100  may be controlled manually through the use of a pendant. The manual movement of workcell  100  may be freeform without any automatic guidance or set path (using, for example, a joystick). In another embodiment, movement is controlled manually but is limited within certain tolerances by a guidance system. In another embodiment, movement is controlled automatically (using, for example, a computer) but is limited within certain tolerances by a guidance system. In another embodiment, movement is controlled by a combination of manual and automatic controls. For example, movement may be controlled by an operator, but automated decisions based on sensors are made regarding such things as speed, turning radius, turning position, stopping position, final location, etc. 
     In an embodiment, the guidance system may not involve, or rely completely on, guide rails. Guidance systems that may be used to control the movement and positioning of workcell  100  include, but are not limited to: optical systems that follow a painted or taped line on the floor, systems that sense and follow a buried wire or magnetic tape; and, systems that are wirelessly guided using positioning information (e.g., GPS, or differential GPS). Another example of a wireless guidance system that may be used involves a laser system wherein a rotating laser sends a beam to stationary reflectors at known locations. Distance and angle measurements from the reflectors may then be used to calculate a position, or series of positions, of workcell  100 . Position measurements may be used by the guidance system to control the movement of workcell  100 . 
     The systems, units, drives, devices, equipment, and functions described above may be controlled by, implemented with, or executed by one or more computer systems. The methods described above may also be stored on a computer readable medium. Many of the elements of workcell  100 , comprise, include, or are controlled by computers systems. 
       FIG. 8  illustrates a block diagram of a computer system. Computer system  800  includes communication interface  820 , processing system  830 , storage system  840 , and user interface  860 . Processing system  830  is operatively coupled to storage system  840 . Storage system  840  stores software  850  and data  870 . Processing system  830  is operatively coupled to communication interface  820  and user interface  860 . Computer system  800  may comprise a programmed general-purpose computer. Computer system  800  may include a microprocessor. Computer system  800  may comprise programmable or special purpose circuitry. Computer system  800  may be distributed among multiple devices, processors, storage, and/or interfaces that together comprise elements  820 - 870 . 
     Communication interface  820  may comprise a network interface, modem, port, bus, link, transceiver, or other communication device. Communication interface  820  may be distributed among multiple communication devices. Processing system  830  may comprise a microprocessor, microcontroller, logic circuit, or other processing device. Processing system  830  may be distributed among multiple processing devices. User interface  860  may comprise a keyboard, mouse, voice recognition interface, microphone and speakers, graphical display, touch screen, or other type of user interface device. User interface  860  may be distributed among multiple interface devices. Storage system  840  may comprise a disk, tape, integrated circuit, RAM, ROM, network storage, server, or other memory function. Storage system  840  may be a computer readable medium. Storage system  840  may be distributed among multiple memory devices. 
     Processing system  830  retrieves and executes software  850  from storage system  840 . Processing system may retrieve and store data  870 . Processing system may also retrieve and store data via communication interface  820 . Processing system  850  may create or modify software  850  or data  870  to achieve a tangible result. Processing system may control communication interface  820  or user interface  870  to achieve a tangible result. Processing system may retrieve and execute remotely stored software via communication interface  820 . 
     Software  850  and remotely stored software may comprise an operating system, utilities, drivers, networking software, and other software typically executed by a computer system. Software  850  may comprise an application program, applet, firmware, or other form of machine-readable processing instructions typically executed by a computer system. When executed by processing system  830 , software  850  or remotely stored software may direct computer system  800  to operate as described herein. 
     In an embodiment, a mobile self-contained robotic workcell, may include a multi-degree of freedom robot arm, a gantry supporting the robot arm, an air bearing that selectively lifts the gantry off of a supporting surface for low-friction movement, a first drive system that engages a first drive surface while the gantry is lifted off of the supporting surface by the air bearing to propel the gantry in a first direction, a second drive system that engages a second drive surface while the gantry is lifted off of the supporting surface by the air bearing to propel the gantry in a second direction, and, a first guide carriage that engages a first guide track, the first guide carriage limiting the gantry to movement in the first direction. The workcell may also include an air compressor supported by the gantry that supplies compressed air to the air bearing for selectively lifting the gantry off of the supporting surface. The workcell may also include power rail contacts that provide power to at least one device supported by the gantry. The at least one device may include the robot arm. The robot arm may have at least 5 degrees of freedom. 
     The first direction may be determined by a first guide rail that is fixed in relation to the supporting surface. The second direction may be determined by a second guide rail that is also fixed in relation to the supporting surface. The second direction may be approximately perpendicular to the first direction. The supporting surface may include the first drive surface and the second drive surface. The two drive surfaces may overlap. 
     The first drive system may be steered by a first guide rail that is fixed in relation to the supporting surface. The second drive system may be steered by a second guide rail. The first guide rail may include a plurality of discontinuous sections. At least two of the plurality of discontinuous sections may be separated in a longitudinal direction by a distance sufficient to allow one or more air bearings to pass between the two of the plurality of discontinuous sections. 
     In an embodiment, a mobile self-contained robotic arm workcell may include a superstructure, a multi-degree of freedom robotic arm supported by the superstructure, and at least one air bearing. The at least one air bearing may selectively lift the superstructure from a position resting on a support surface to an elevated position. The elevated position may allow for low friction movement of the superstructure across the support surface. A guide carriage that engages a first guide rail may direct a first movement of the superstructure while the superstructure is moved in the elevated position. 
     Power rail contacts may provide power to at least one device supported by the superstructure. The at least one device may include an air compressor that supplies compressed air to the at least one air bearing. The robot arm may have at least 2 degrees of freedom. 
     A first guide rail may direct the first movement of the superstructure in a first direction. A second guide rail may direct a second movement of the superstructure in a second direction. The first direction and the second direction may be substantially perpendicular. 
     The first guide rail and the second guide rail may both direct the superstructure in the first direction. The first guide rail and the second guide rail may be separated by a gap that allows the air bearing to pass in a second direction between the first guide rail and the second guide rail. A second guide carriage may engage the second rail while the first guide carriage is disposed in the gap. 
     In an embodiment, a robotic arm workcell includes superstructure means for supporting a multi-degree of freedom robotic arm and air bearing means for selectively lifting the superstructure from a position resting on a support surface to an elevated position. The elevated position allows for low friction movement of the superstructure across the support surface. Drive means propel the superstructure across the support surface in at least a first direction and a second direction. Guide means limit a direction of travel of the superstructure while being propelled across the support surface to one of the first direction and the second direction at a time. 
     Air supply means, which may be supported by the superstructure, may provide compressed air to the air bearing means. Power contact means may provide power to the drive means while the superstructure is being propelled across the support surface. The power contact means may engage a fixed power rail. The guide means may selectively engage a first guide rail to limit the direction of travel of the superstructure while being propelled across the support surface to the first direction. The guide means may engage a second guide rail to limit the direction of travel of the superstructure while being propelled across the support surface to the second direction. 
     In an embodiment, a method of moving a robotic arm includes activating an air compressor contained on a workcell to supply air to an air bearing. The air bearing lifts the workcell from a position resting on a support surface to an elevated position. The elevated position allows for low friction movement of the workcell across the support surface. A first guide carriage is engaged with a first guide rail to limit a movement of the workcell across the support surface to a first direction. A first drive system is engaged to propel the workcell across the support surface in the first direction. A second guide carriage is engaged to a second guide rail to limit the movement of the workcell across the support surface to a second direction. A second drive system is engaged to propel the workcell across the support surface in the second direction. 
     The first guide carriage may be engaged to a third guide rail to limit a movement of the workcell across the support surface to the first direction. The first drive system may be engaged to propel the workcell across the support surface in the first direction and guided by the third guide rail. The air bearing may be deactivated to lower the workcell to a position resting on the support surface. A first robotic arm that is attached to the workcell may be activated. 
     A first power rail may be engaged to receive power for the compressor during the movement of the workcell across the support surface in the first direction. A second power rail may be engaged to receive power for the compressor during the movement of the workcell across the support surface in the second direction. A third power rail may be engaged to receive power for the compressor during the movement of the workcell across the support surface in the first direction while the workcell is being guided by a third guide rail. The air bearing may be deactivated to lower the workcell to a position resting on the support surface. Power for a robotic arm that is attached to the workcell may be received via the third power rail. 
     The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that this application be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.