Abstract:
A positioning system, a robot that employs the positioning system and a method of assembling the robot. The positioning system typically includes a stator and a linear variable reluctance motor that moves along the stator, wherein the stator, besides having an electromagnetic purpose, also acts as the sole structural beam element for the motor to rest upon. The robot employs the positioning system such that subsystems can be attached directly to the motor.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     This invention relates to positioning systems used in Cartesian robots and, more particularly to a positioning systems incorporating drive systems using linear variable reluctance motors.  
         [0003]     2. Related Art  
         [0004]     Cartesian robots often comprise multiple positioning systems for moving one or more subsystems, which the robot needs to manipulate, in an X-Y plane. The subsystems are moved typically in both the X and Y-direction, within the plane, but can also just be manipulated in only one of the two axes (i.e., X OR Y-direction) in the X-Y plane. The positioning systems typically comprise a carriage that rides along linear bearings along a structural beam, a first (e.g., “X”) direction. The structural beam, in turn, rides at either, or both, of its ends on linear bearings in a second (e.g., “Y”) direction. The motive force for the system is typically provided by electrical servo motors with either a lead screw or a belt connected thereto or a linear motor that electromagnetically generates a force between the moving parts.  
         [0005]     For the drive in the Y-direction, a single sided drive system drives only one end of the structural beam, relying on the stiffness of the Y-bearing to maintain perfect, or near perfect, perpendicularity of the structural beam during its horizontal movement. Alternatively, dual drives may be used to drive both ends of the structural beam at the same time.  
         [0006]     A subsystem, which a robot needs to manipulate, may be a tool for picking up and placing objects. The tool may either grip the object or use vacuum to hold the object. For example, robots will manipulate a subsystem comprising a head with vacuum nozzles to assemble printed circuit boards. Another subsystem a robot needs to manipulate may comprise a tool for dispensing material. For example, robots will use a subsystem comprising a dispenser to apply a material on to a surface either by dispensing dots of material or by dispensing the material along a path. The subsystem may also comprise a camera, which the robot needs to move, such that the camera may view various objects of interest. The subsystem the robot needs to manipulate is not limited to the examples described above and may further comprise control devices such as printed circuit boards, valves and the like, necessary to manipulate the tooling. For example, the subsystem may include the ability to turn a vacuum nozzle on and off, to capture and possibly process an image, to move the tool or the subsystem itself in the Z-axis, etc.  
         [0007]     As depicted in  FIG. 1   a , is a lead screw positioning system  10  of the related art. Lead screw positioning system  10  comprises a motor  12 , lead screw  16 , ball nut  14 , carriage  18 , structural beam  20 , and linear bearing  22 . Motor  12  rotates lead screw  16  upon which ball nut  14  is mounted and thus provides the motive force to move ball nut  14  along the linear axis (i.e., parallel to lead screw  16 ). The top of carriage  18  attaches to ball nut  14  and the bottom of carriage  18  rides on linear bearing  22 .  FIG. 1   b , depicts a variable reluctance positioning system  30  of the related art. Variable reluctance motor (hereinafter VRM) positioning system  30  comprises motor  32 , stator  34 , carriage  18 , two structural beams  20 , and two linear bearings  22 . Relative motion between motor  32  and stator  34  upon which carriage  18  is mounted provides the motive force to move carriage  18  along the linear axis (i.e., parallel to stator  34 ). Top and bottom of carriage  18  ride on linear bearing(s)  22 . In both the lead screw positioning system  10  and VRM positioning system  30 , linear bearing(s)  22  are mounted on structural beam(s)  20 . For the lead screw positioning system  10 , the combination of lead screw  16 /ball nut  14  and linear bearing  22 /structural beam  20  stabilize carriage  18  by preventing the rotation of carriage  18  about the X, Y and Z axes and the translation of carriage  18  in the axis perpendicular to the linear axis. In the case of the VRM positioning system  30 , the two sets of linear bearings  22 /structural beams  20  provide carriage  18  with the same stability.  
         [0008]     Mounted to carriage  18  is subsystem  100 , in both of the related art systems  10  and  30 . In these embodiments, subsystem  100  comprises a head used for picking and placing components onto a printed circuit board using vacuum nozzles  102 .  
         [0009]     The above-described construction of the positioning system results in a high cost, high weight, and lower speeds because this system requires the use of both the structural beam and bearing(s) to effectively operate.  
         [0010]     A need exists for a Cartesian robot incorporating a positioning system that overcomes at least one of the aforementioned and other deficiencies in the art.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention overcomes the cost and complexity of building a Cartesian robot by providing a positioning system that is simplified.  
         [0012]     A first general aspect, provides a robot comprising:  
         [0013]     at least one positioning system comprising a motor and a stator; and  
         [0000]     at least one subsystem, wherein said at least one subsystem attaches directly to said motor.  
         [0014]     A second general aspect, provides a positioning system comprising:  
         [0015]     a stator; and  
         [0016]     a linear variable reluctance motor configured for linear movement along said stator, further wherein said stator acts as a structural beam for said motor.  
         [0017]     A third general aspect, provides a method for assembling a robot, the steps comprising:  
         [0018]     providing at least one positioning system comprising a motor and a stator;  
         [0019]     providing at least one subsystem; and  
         [0020]     attaching said at least one subsystem directly to said motor.  
         [0021]     A fourth general aspect, provides a positioning system for use with a robot said positioning system comprising:  
         [0022]     a motor;  
         [0023]     a stator, wherein there is a relative motion between said motor and said stator, further wherein said positioning system does not have a separate structural beam. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent detailed description, in which:  
         [0025]      FIG. 1   a  is a front view of an assembled lead screw positioning system of the related art;  
         [0026]      FIG. 1   b  is a front view of an assembled variable reluctance motor positioning system of the related art;  
         [0027]      FIG. 2  is a top, perspective view of an embodiment of an assembled positioning system, in accordance with the present invention;  
         [0028]      FIG. 3  is a front view of the embodiment in  FIG. 2 , in accordance with the present invention;  
         [0029]      FIG. 4  is an end view of the embodiment in  FIG. 2 , in accordance with the present invention; and  
         [0030]      FIGS. 5   a  through  5   e  are top views of various embodiments of assembled position systems, in accordance with the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     Although certain embodiment of the present invention will be shown and described in detail, it should be understood that various changes and modification may be made without departing from the scope of the appended claims. The scope of the present invention will in no way be limited to the number of constituting components, the materials thereof, the shapes thereof, the relative arrangement thereof, etc. and are disclosed simply as an example of an embodiment. The features and advantages of the present invention are illustrated in detail in the accompanying drawings, wherein like reference numerals refer to like elements throughout the drawings.  
         [0032]     The present invention pertains to a Cartesian robot having an X-Y positioning system comprising a drive system that eliminates the need for a separate structural beam(s), a separate attachment carriage, and the linear bearing(s) necessitated by the related art. The inventive apparatus of the drive system comprises a simplified system that includes a linear variable reluctance motor that also acts as a carriage, and a stator that also acts as a structural beam. Therefore, since the motor acts as the carriage, any subsystem that the robot needs to manipulate may be attached directly to the motor. Further, elimination of the carriage in turn eliminates the need for the separate structural beam(s) and the linear bearing(s).  
         [0033]     One embodiment of the present invention is shown in various views in  FIGS. 2 through 4 , and  5   a . The system, denoted by a  40 , includes a motor  32  and a stator  34 . The motor  32  is typically a linear variable reluctance motor  32 . Depending on the configuration of the embodiment, either the motor  32  or the stator  34  moves linearly in relationship to the other.  
         [0034]     Further attached to the motor  32  is at least one subsystem  100 . The subsystem  100  can be one type, or a plurality of types of subsystems  100  which the Cartesian robot needs to move in the X-Y plane. For example, as shown in  FIGS. 2 through 5 , the subsystem  100  can be, for example, any type suitable for use in a printed circuit board (PCB) component placement machines. The subsystem  100 , for example, may comprise a pick and place head, which further comprises a gripper or a vacuum nozzle  102 , or subsystem  100  may comprise a material dispenser, a camera, or combinations thereof. Subsystem  100  may also further comprise any control devices such as printed circuit boards, valves and the like necessary to manipulate a gripper, camera, dispenser, etc. Similarly, the subsystem  100  is not limited to subsystems  100  only for PCB component placement machines, but the subsystem  100  or a plurality of subsystems  100  may be any such tooling, or element, that the robot needs to move in the X-Y plane to complete one or more tasks.  
         [0035]     One advantage of the present invention includes the capability to directly attach the subsystem  100  to the motor  32 , or portion of the motor  32 . That is no “interstitial” mechanism (e.g., carriage) is required to attach to the motor  32  and structural beam, that, in turn, is the attachment means for the various subsystems  100 . Instead the subsystem(s)  100  may be attached directly to the motor  32  without any intervening carriage, or functionally equivalent or similar mechanism(s).  
         [0036]     Still another advantage of the present invention is that the stator  34  does not require a separate structural beam of any sort on which to assist in the linear movement of the motor  32 . Thus, the stator  34  acts functionally as the structural beam for the motor  32  to reside and move along, in addition to being an electromagnetic component that interacts with the motor  32  as part of the system  40 . The structural beam functionality of the stator  34  ensures perfect, or near perfect, linear movement of the motor  32 . Stator  34  rides between bearings  36 . The combination of stator  34  with bearings  36 , which stabilize subsystem  100  as it moves along the linear axis. Optional bearings  38  provide additional stability to subsystem  100 . Other configurations of bearings could also be used to stabilize subsystem  100 . For example, bearings (not shown) may be provided along the corners of the stator  34 .  
         [0037]     Note too that while  FIGS. 2 through 4 , and  5   a , depict the motor  32  moving in a generally X-direction of an X, Y, Z system, clearly in other embodiments, the system  40  may be configured to move in the Y or Z-direction. So too with the configuration of the stator  34  can have other configurations. For example, the stator  34  while lying along the X-axis (see  FIG. 2 ), thus allowing motor  32  to move along the X-axis, alternatively the stator  34  can be configured to lie along the Y-axis, thus allowing Y-axis movement of the motor  32 .  
         [0038]     Further, as shown in  FIGS. 5   b  through  5   e , additional motor(s)  32  and stator(s)  34  (i.e., additional robotic positioning system(s)  40 ) may be used. For example, what could be termed a “first” stator  34  (see  FIG. 3   b ) shown can similarly ride on one, or more, “second” motor  32 . Thus, allowing the entire “first” motor system  40  to then further move within the X-Y plane along the Y-axis. That is an end of the stator  34  can be attached to a second motor  32  which, in turn, moves along a “second” stator  34 . In addition, multiple motor(s)  32  may ride on multiple stators  34  in various combinations as shown in  FIGS. 5   c  through  5   e.    
         [0039]     Since other modification and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modification which do not constitute departures from the true spirit and scope of this invention.