Abstract:
A manufacturing system is provided for automatic assembly, testing and/or packaging of a variety of products. The system is based on utilization of one or more robotic modules, each having a programmable servo-driven linear actuator of a rod type, combined with slides, and standardized extrusions that form guide rails and a frame to support the actuators. The standardized extrusions include a plurality of faces, with a groove formed in at least one of the faces. Each slide fits in one of the grooves and is attached to the actuator rod, which moves the slide along the guide rails. The guide rails provide structural support to the slides in every direction that a load is attached to the slides, and include grooves to direct the motion of the slides. Two or more such robotic modules, each being positioned in a Cartesian coordinate relationship to one another, complete a system. Each module houses a dedicated controller that operates its respective actuator. The dedicated controller, in turn, connects to a remote computer or industrial controller such that a programmed sequence for robotic motion can be provided by the computer to control movement in the system in all three Cartesian directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to provisional application Ser. No. 60/241,435 filed Oct. 19, 2000, entitled “Modular Robotic Device And Manufacturing System”, and which is incorporated herein by reference. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates to automatic manufacturing equipment used for assembly and/or processing of products. More particularly, it relates to a high rate, flexible, automatic production system employing one or more robotic modules, each having a programmable servo-driven actuator, where each actuator is combined with slides mounted in guide rails that are part of an extruded structural frame to provide single direction linear robotic motion.  
           [0004]    Current automated assembly or processing equipment for special products is typically custom tailored to one or more specific products, and designed to provide positioning or placement for end effectors or tools. Such automatic machines or systems consist of product feeding equipment (feeders, conveyors, magazines, trays etc.) and transfer equipment to move and position product from station to station. Several well-known transfer systems have been employed in automatic assembly. Transfer system types include rotary dial, indexing conveyor, indexing chain, belt, walking beam or palletizing conveyor, that work in combination with stop and lift/register devices.  
           [0005]    A typical automatic assembly system may also employ so-called “positioning” or “placement” devices that utilize many different types of actuators. An actuator is a displacement device that activates, or repositions by force, a movable member of the machine, and may, for example, be pneumatic cylinders (compressed air operated), hydraulic cylinders (compressed fluid operated), or electrical motors in combination with belts, chains, gears or feed screws. The positioning device actuators are generally used to provide a so-called “pick and place” motion to the movable member. They can be used to retrieve a product from a feeding device and place the product onto a transfer device.  
           [0006]    Sometimes the pick and place devices rely on the use of a cam-driven actuator to provide controlled acceleration/de-acceleration and achieve high speed for product placement. Such devices have a number of limitations and drawbacks. A rotating cam action typically is limited to a single position for points of pick-up and placement. Yet, more significantly, because its shape defines all motion parameters and cannot be changed quickly, a cam is limited to a single movement pattern. Thus, while a cam actuation device can provide fast product transfers, it cannot be used for more than a single point-to-point transfer without substantial modification.  
           [0007]    Pneumatic cylinders are low cost and widely used in automated assembly machinery. However, this type of device generally doesn&#39;t have programmable position control or programmable acceleration and velocity. Thus utilization of pneumatic cylinders is limited to simple pick and place movements using mechanical stops for registration. The individual cylinders cannot be reprogrammed. Hence, these devices cannot be automatically changed for different positions. In addition, pneumatic cylinders exhibit high failure rates due to wear and require extensive maintenance, including repeated mechanical adjustments to control accurate position.  
           [0008]    Pneumatic cylinders also suffer from an inability to maintain constant acceleration and velocity. This is due to the large number of variables that impact the function of the cylinders, such as: friction (lubrication), temperature fluctuation, air pressure fluctuation, air flow fluctuation, air leakage, moisture content in the air lines, wear of seals, bushings, and bearings, and contaminants inside the cylinder. Thus, application of this device is limited to pick and place or simple positioning of a tool when both pick up and destination points are fixed.  
           [0009]    A servo-controlled robotic device is generally more expensive and frequently custom designed to include a complete device that is built with its own support and mechanical guiding means and a programmable controller for a single or several devices. Several standard linear robotic devices, manufactured by robotic companies are available as self-enclosed and fully integrated linear robotic modules. They can be mounted together to construct one-, two- or three-axis robots typically controlled by a single controller. Frequently such devices have performance that allows completion of motion with programmable control for acceleration/deceleration, velocity and position. However, the cost of these devices is high and often precludes their use due to high level of investment. It is known that high cost of investment in equipment frequently cannot be justified based on the benefit it produces.  
           [0010]    For many products the manufacturing and assembly processes consist of many different steps, involving a large number of specialty parts. This makes standardization of the manufacturing robotics difficult. Many attempts have been made to create a standardized, programmable robotic device or system, that can provide a more cost effective and flexible approach to this dilemma. Such a system must be capable of being used for more then one application, with enough flexibility to manufacture more then one product.  
           [0011]    The robotic devices are readily available to allow creation of such systems, but at a relatively high cost. The costs of such systems, in fact, are often so high as to outweigh the potential benefits of implementing dedicated automatic manufacturing systems.  
           [0012]    The ability to create a low-cost programmable, servo-driven, multi-axis robot and construct modular automatic systems based on such robots is extremely important to the manufacture and assembly industry, and can provide substantial economic benefit.  
         BRIEF SUMMARY OF THE INVENTION  
         [0013]    In accordance with the teaching in this invention, the automatic system employing robotic linear devices is described for assembling and/or processing product or part. More particularly, the system is a high rate, flexible, automatic production system employing one or more robotic modules, each having a programmable servo-driven actuator, where each actuator is combined with slides mounted in guide rails that are part of an extruded structural frame to provide single direction linear robotic motion. Unlike expensive machined parts in conventional robotic devices, the guide rails and frame are formed from inexpensive, standardized and pre-formed extrusions, of low cost materials such as aluminum. These components can be quickly cut to a wide range of lengths, and readily assembled with low cost fasteners to provide great versatility in the dimensions of each module. The modules can be mounted in a Cartesian multi-axis relationship to provide linear positioning in three-dimensional space.  
           [0014]    Hence, this invention describes a novel, cost effective and versatile robotic device that can be programmed or controlled directly to effect automated movements in one-, two- or three-dimensional Cartesian space. Furthermore, the invention is not limited to applications as a stand-alone device, but may be configured in combination with selected automation components to create a unique, cost effective and highly flexible manufacturing system.  
           [0015]    The modular robotic system of the invention provide a high rate for automatic assembly system, yet employ a relatively slow moving mechanism to achieve very high throughput for assembly or processing. Conventional systems used for high speed assembly (i.e., 50 to 500 parts per minute) rely on high speed or high rate of acceleration/deceleration for indexing or transfer of a single part from one working station to another. The proposed system is based on a single index per batch. Batch size can be 4 to 400 parts. For example, for a 60 parts per minute rate system, indexing one part every cycle on conventional high speed system with 5 seconds index time, will take 0.5×60 parts or 30 seconds of unused time (50%) for transfers. The proposed system with a batch size of 60 parts will be indexed in 3 seconds.  
           [0016]    A proposed system comprises standard robotic devices, has a measurable and predictable mean time to failure based on actual tests, and can be presented in hours of product life before potential failure. For example, factory published data for servo actuators used by the invention, traveling at 12″ per cycle at 10 cycles per minute, gives a 3 meters per minute rate of travel. A published life span for one-kilogram load is 4,000 KM, resulting in 4,000,000 meters divided by 3 meters which corresponds to 133 million minutes or 21,666 hours. The system operating 2 shifts at 16 hours per day will have 1,354 days or 5.4 years (250 days per year) before failure. This predictable reliability provides calculated uptime for equipment and gives predictable payback on investment. Unlike conventional custom equipment with unpredictable behavior and unknown reliability a proposed system has standardized robotic devices and standardized transfer and controls.  
           [0017]    As noted, the system is made from one or more modular units each of which perform a specific function. Each modular unit includes a frame made from an extruded structural member. At least one servo-controlled linear actuator is mounted in the unit. The actuator includes a body, a rod which is extendible and retractable relative to the actuator body, and a dedicated controller which moves the rod. A control system, such as computer, is in communication with the actuator controller, and, sends signals to the actuator controller to extend and retract the actuator rod according to a desired pattern or program. A slide rail is mounted to a structural member of the unit and a slide is slidable along said slide rail. The actuator rod is operatively connected to the slide to move said slide along said slide rail in response to signals from the control system. A machine part is connected to the slide to perform an operation on the parts. The machine part, for example, can be a rake which accepts parts from a feeder system; a tray which moves a quantity of parts from one location to another, or a gripper which moves product or parts from the rake to the tray. Other types of machine parts could be provided to perform other functions to the parts.  
           [0018]    The unit can include a single actuator, to move the machine part along a single axis. Alternatively, the unit can include two or three actuators to move the machine part in two or three axis. In a “two-axis” unit, a first actuator and a second actuator are mounted in the modular unit. The rod of the first actuator moves in a first axis and the rod of the second actuator moving in a second axis. The second actuator is operatively connected to the first actuator rod to be moved in the first axis by the first actuator. The machine part, then, is operatively connected to the second actuator rod to be moved in the second axis by the second actuator. Hence, controlled movement of the first and second actuator rods by the control system moves the machine part in two axes.  
           [0019]    In a “three-axis” system, the modular unit includes a first actuator, a second actuator, and a third actuator mounted in the modular unit. The rod of the first actuator moves in a first axis, the rod of the second actuator moves in a second axis offset from the first axis, and the rod of third actuator moving in a third axis offset from both the first and second axes. In effect, the first and second axes define a plane, and the third axis is offset from (or intersects) the plane defined by the first and second axes. The second actuator is operatively connected to the first actuator rod to be moved along the first axis; the third actuator is operatively connected to the second actuator rod to be moved along the second axis; and the machine part is operatively connected to the third actuator rod to be moved along the third axis. Hence, controlled movement of the first, second, and third actuator rods by the control system moves the machine part in three axes.  
           [0020]    The structural members used to construct the modular units allow the units to be modular in form; to be easily connected to each other; and to thus easily construct a complete processing line to process a particular product. The structural member is cut from an extruded member and includes a plurality of side faces and a pair of end surfaces. The extruded member can be triangular, quadrilateral, hexagonal, or have any other regular or irregular polygonal shape in cross-section. A groove is form in at least one of the faces (and preferably all of the faces) and a hole is formed in at least one of the end surfaces of the extruded member. The groove is generally T-shaped and had a base portion and a narrower neck portion extending from the base portion to the face of the extruded member. A headed part is receivable in the groove to connect a plurality of structural members together, to mount the slide rail to the structural member, or to mount the machine part to the structural member. The headed part can be a button or a threaded fastener (i.e., a screw or bolt). Another headed part is received in (or extends from) the hole at the end surface to allow for two structural members to be connected together in a T-shaped form.  
           [0021]    Additionally, the slide and the linear actuator are mounted to the extruded member using headed parts (i.e., buttons, bolts, screws, etc.). 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0022]    In the accompanying drawings, which form part of the specification and wherein like numerals and letters refer to the like parts wherever, they occur:  
         [0023]    [0023]FIG. 1A is a perspective view of a single-axis robotic module formed in accordance with the present invention;  
         [0024]    [0024]FIG. 1 is a perspective view of another single axis robotic modular unit;  
         [0025]    [0025]FIG. 2 is an exploded view of the assembly of FIG. 1;  
         [0026]    [0026]FIG. 3 is a perspective view of the module of FIG. 1;  
         [0027]    [0027]FIG. 4 is a cross-sectional view taken along line  4 - 4  of FIG. 3;  
         [0028]    [0028]FIG. 5 is a perspective view of a single axis robotic modular unit including a bowl feeder assembly system with a movable rake for batch processing;  
         [0029]    [0029]FIG. 6 is a top plan view of the bowl feeder assembly with a rake system of FIG. 5;  
         [0030]    [0030]FIG. 7 is an elevational view of the bowl feeder assembly system taken along line  7 - 7  of FIG. 6;  
         [0031]    [0031]FIG. 8 is a cross-sectional view of the bowl feeder assembly system taken along line  8 - 8  of FIG. 6;  
         [0032]    [0032]FIG. 9 is a perspective view of a three-axis robotic modular unit;  
         [0033]    [0033]FIG. 10 is an exploded view of the assembly of FIG. 9;  
         [0034]    [0034]FIG. 11 is a perspective view of an assembly apparatus employing the single axis modular unit having a bowl feeder and the three axis modular unit;  
         [0035]    [0035]FIG. 12 is a perspective view of another assembly apparatus employing multiple robotic modular units;  
         [0036]    [0036]FIG. 13 is a schematic of a three-directional robotic module connected to a single remote computer; and  
         [0037]    [0037]FIG. 14 is a schematic of a single-direction robotic module connected to a remote computer. 
     
    
       [0038]    Corresponding reference numerals will be used throughout the several figures of the drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0039]    The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what we presently believe is the best mode of carrying out the invention.  
         [0040]    As will be described below, the invention resides in robotic modules which can be assembled together using frame members in various desired configurations depending on the desired operation to be carried out by an assembly.  
         [0041]    A single robotic module M is shown in FIG. 1A. The robotic module M includes a programmable servo-driven linear actuator  1  of a rod type mounted to a frame member  3 . The frame member  3  is an extruded member that is generally square in cross-section. However, the extruded frame member could be any regular or irregular polygonal shape in cross-section. A groove  5  extending longitudinally along at least one face (and preferable along all the faces) of the member  3 . The groove  5  is generally T-shaped, having a neck section  5   a  and a wider inner section  5   b . A hole  6  opens at each end surface  6   a  of the extruded frame member  3 . Because the frame member  3  is an extruded form, the hole  6  extends longitudinally through the center of the member  3 . A slide rail  7  is mounted on the frame member  3  above the groove  5 . The slide rail  7  can be shaped to conform to the shape of the groove to be slid into the groove, and to be held frictionally in place in the groove  5 . Alternatively, the slide rail  7  can be mounted to the frame member  3  on the face of the member  3  and over the groove  5 , as seen in FIG. 1A. In this instance, the slide rail  7  can be held in place by screws which pass through threaded holes  7   a  in the rail  7 , and which are received in nuts (not shown) which fit within the wider section  5   a  of the groove  5 . Hence, when the screw is received in the nut, the nut will be pulled against the neck  5   a  (or outer surface of the groove portion  5   b ) to frictionally hold the slide rail  7  in place on the frame member. The slide rail  7  is somewhat hour-glass shaped in cross-section. It has flat or level top and bottom surfaces, but its side surfaces are indented, to define a groove along the side of the rail  7  which extends the length of the rail  7 . A slide  9  is mounted on the rail  7  to slide relative to the rail  7 . The slide  9  has a generally flat upper surface  9   a  with a pair of ears  9   b  extending from opposite sides of the slide  9  and a lower surface having a groove  11  formed therein. The groove  11  corresponds in shape to the profile of the slide rail  7  so that the slide  9  can move longitudinally along the slide  7 , yet cannot be raised off the slide rail  7 .  
         [0042]    The modular unit M includes at least one linear actuator  1 . The modular unit of FIG. 1A is a single axis module, and hence includes only one actuator  1 . The actuator  1  has a positioning rod  13  movable inwardly and outwardly relative to a housing  14 , a dedicated controller  15 , and a control cable  17 . The linear actuator  1  is mounted to the extruded frame member  3  by a screw, bolt, button, or other headed member (not shown). The headed member includes a head which is received in the frame member groove  5  and a stem which extends through the groove neck  5   a  and into the linear actuator. The linear actuator can also have a threaded shaft extending from its housing  14  or controller  15 , which can extend into the frame member groove  5 . A bolt which can slide through the groove is then applied to the shaft. The cable  17  places the controller  15  in communication with a computer C (FIG. 14) or other control device which sends signals to the controller  15  to extend and retract the rod  13 . The computer C controls the extension of the rod, as well as the velocity and acceleration of the rod. The rod  13  is operatively connected to the slide  9 . In FIG. 1A, the rod  13  is shown connected directly to the slide  9 . Hence, the computer C controls the position, and well as the velocity and acceleration of the slide  9 . As can be appreciated, and as will be discussed below, the module M can be used by itself to form a single direction assembly, or two or more modules can be interconnected to form assemblies which move parts in two or three directions or axes.  
         [0043]    Turning to FIGS.  1 - 4 , another single-axis modular unit M is assembled in a frame  20  to move a plate  21  in one direction. In this instance, the modular unit M includes a pair of parallel side members  23  which are spaced apart by end members  25 . Slide rails  7  are mounted on the side members  23 ; two slides  9  are placed on each slide rail  7 ; and the plate  21  extends across, and is mounted to, the top surface of each of the slides  9 . The module M is supported above the ground by legs  27  which have feet  28  at the bottoms of the legs  25 . An opened case  29  surrounds the plate  21 , and includes four vertical members  31  extending up from the ends of the side members  23 ; a first pair of horizontal members  33  extending between the vertical members  31  above the side members  23  and; and a second pair of horizontal members  35  extending between the vertical members  31  above the end members  25 .  
         [0044]    The side members  23 , end members  25 , legs  27  are all formed from lengths of the extruded member  3 . They are connected to each other by means of buttons, screws, bolts, or other headed members which extend from the holes  6  of the members  3  and have heads which are received in the grooves of adjacent members  3 . Thus, for example, the end members  25  each have a headed member (not shown) extending from opposite ends of the frame members; and the head of the headed member is received in the groove  5  of the side members  23  to form the square shaped frame for the linear actuator of the module M. The legs  27  are similarly connected to the bottom faces of the side members  23 ; and the members of the open case  29  are similarly connected to each other, and to the side members  23  to form the unit  20 . The extruded member  3 , from which all the unit members are made from are preferably extruded from aluminum. However, they can be produced from any other desired material which can be extruded, and which will withstand the withstand the environment to which the modular assembly will be subjected. Alternatively, if standard lengths of members  3  are to be used, the members  3  can be molded.  
         [0045]    The actuator  1  of the module M is mounted to one of the end members  25  using screws, in the same manner that the frame members are connected together. As seen in FIG. 4, the housing  14  of the actuator  1  includes T-shaped grooves  26  which receive screws or buttons which, in turn, are received in the slots  5  of the end members  25 . As can be appreciated, the module M of the unit  20  operates to move the plate  21  horizontally along the slide rails  7 . The plate  21 , like the member  3 , is an extruded member. As seen, it essentially is two members  3  fused together. It has a groove  22   a  in each of the side faces and a pair of parallel grooves  22   b  in its upper and lower faces. Additionally, a hole  24  extends parallel to the grooves  22   a,b;  the holes being in line with the grooves  22   b  in the upper and lower faces of the plate  21 . The grooves  22   a,b  are identical in configuration to the grooves  5  of the members  3 . Hence, other frame members can be connected to the plate  21 . It will be appreciated that the member from which the plate  21  is made can also be used as a frame member in a modular unit.  
         [0046]    Turning to FIG. 14, instructions from the remote computer C are sent via the control cable  17  to the dedicated controller  15 . Based upon those instructions, the dedicated controller  15  directs the actuator  1  to move the positioning rod  13  inwardly or outwardly at a specified rate for a specified period of time. This in turn causes the plate  21 , in conjunction with the slides  9  to translate along the slide rails  7 . In this way, the remote computer C can repeatedly direct the plate  21  to move to a desired location along the side members  23  at a desired rate of speed. The instructions for the movements of the plate  21  can be input directly into the remote computer C by an operator for instantaneous results, or the instructions can be programmed into the remote computer C by the operator to enable timed and/or complex automated sequences for the movements of the plate  21 .  
         [0047]    The single-axis module M, as exemplified in FIGS.  1 - 4 , can be used in manufacturing and assembly applications where robotic translation is only necessary in a single Cartesian direction. An example of a single direction application is shown in FIGS.  5 - 8 . Here, a unit  30  uses a single-axis module Ml is paired with a bowl feed device B. The module M 1  moves a rake  31  having pockets  33  along a Cartesian axis X such that the bowl feed device B can precisely place parts or product P into the pockets  33  with proper orientation. The rake pockets  33  have a center to center distance corresponding to center distances for a gripper which will pick up the parts P and to center-to-center distances for a plate where the gripper will deposit the product P. The part fed by the feeder enters the rake pocket  33  due to vibration or air-flow action of the bowl feeder assembly B. The part is retained with in the rake pocket P, for example, by magnets (for magnetically activated parts—parts having iron in them) or by vacuum suction provided by channels routed through the rake member. The retaining force is designed to maintain the position of the part in the rake during rake movement as the rake is indexed through the space to receive the part P from the feeder B and to keep the parts in their proper orientation to be picked up by grippers, as discussed below.  
         [0048]    In this configuration the proposed robotic device is used in conjunction with a specially designed feeding device consisting of a feeder such as a so-called “Vibro Bowl” or “Centrifugal Bowl.” Both devices are used for handling parts, starting with bulk; they are designed to move and orient parts and to feed parts in a single file, back to back, so that parts move to a discharge point in a certain orientation. Such devices can provide a feeding rate from several units per minute to several hundreds of units per minute.  
         [0049]    As seen, the module M 1  is somewhat similar to the module shown in FIG. 1A. The module M 1  uses a single frame member  35  (identical to the frame member  3 ). As seen more clearly in FIG. 7, the actuator  1  is mounted to one face of the member  35 ; a slide rail  7  with a pair of slides  9  is mounted to another face of the member  35 ; and the rake  31  is mounted on the slide  9 . The actuator rod  13  is connected to the plate (and slides  9 ) by means of a connector  37 . Hence, the actuator  1  is controlled by the computer C to move the rake  31  in the axis X along the rail  7  to align the rake slots  33  with the feed ramp of the bowl assembly B, so that the pellets or parts P can be placed in the rake slots  33  by the feeder to create a single batch. A single batch of parts is picked and placed by multiple grippers  114  FIG. 8 and FIG. 11. The module M 1  is supported above the ground by legs  41 . Horizontal members  43  extend perpendicularly from the bottom of the legs  41 , and the bowl feeder assembly B is supported on the members  43 . The members  43  and legs  41  are both made from cut lengths of the extruded member  3 ; and are connected to the legs  41  and the legs  41  are connected to the member  35  in the same manner as described above in conjunction with the module M of FIG. 1.  
         [0050]    An object of this invention is to provide a complete robotic cell that is comprised of a stand-alone robotic device (such as a Robo-Mat® available from Rapid Development Services, Inc. of Chesterfield, Miss.), a servo actuator and a feeder. A combination of a single line feeder bowl with so-called inline feeder or gravity guide connected to a bowl and servo actuator carrying an inline rake member. The inline rake member has equally spaced cutouts to match the outer shape of the part in one of four quadrants of part outline. In other words, the shape of the part side facing the direction of discharge is duplicated in a described cut out. A servo actuator carrying the rake is programmed to stop at each position when the rake cut-out or packet is aligned with a part. The part is directed by feeder under continuous backpressure to move the part into the packet. The servo actuator advances the rake to a next position until all positions are filled with the parts in the same orientation. A center distance from part to part supported by rake is selected to be the same as the distance between pick up end effectors mounted on the robotic device.  
         [0051]    As seen in FIG. 9, a more than one robotic module can be interconnected to form a unit  60  which moves a plate  61  in three axes or directions. The unit  60  includes three modules M 2 , M 3  and M 4  which are supported in a frame  63 . The frame  63  includes side and end members  65  to form a quadrilateral base  66 , legs  67  having feet  69  which support the base above the ground, and an open case  69  which surrounds the three modules M 2 -M 4 . The open case  69  is constructed substantially the same way as the open case  29  which surrounds the module M of FIG. 1. The side and end members  65 , the legs  67 , and the members of the open case  69  are all formed from cut lengths of the extruded member  3 , and are interconnected as described above.  
         [0052]    The interconnection of the three modules is shown more clearly in FIG. 10. Module M 2  includes a pair of parallel spaced apart side members  71  extend between two opposed side members  65  of the base  66 . The members  71  are formed from cut lengths of the extrusion  3 , and are connected to inner faces of the base side members  65 . Slide rails  7   a  are mounted on the side members  71 , and a pair of slides  9   a  is placed on each rail  7   a . An actuator  1   a  is mounted to one of the base side members  65  between the side members  71  so that its rod  13   a  extends and retracts along an axis X that is parallel to the side members  71 .  
         [0053]    The module M 3  includes a pair of parallel side members  81  which are spaced apart by a pair of end members  83 . As seen, one of the end members is formed from a cut length of the extrusion  3 , and the other end member is cut from a length of an extruded member from which the plate  31  (FIG. 1) is cut. The side members  81  are mounted to the slides  9   a  of module Ml; and one of the slide members  81  is connected to the actuator rod  13   a  of module M 1 . Hence, Module M 1  moves module M 2  in the X-axis. In module M 2 , slide rails  7   b  are mounted to the side rails  81  to be in a Y-axis (and to be perpendicular to the slide rails  7   a ). Slides  9   b  are slidable along the slide rails  7   b : and a cross member  85  (identical to the plate  31 ) extends between the side members  81  and is mounted to the slides  9   b  at its opposite ends. The actuator  1   b  is mounted to one of the end members  83  between the side members  81 , such that its rod  13   b  extends and retracts in the Y-axis. The rod  13   b  is connected to the cross-member  85  to move the cross-member  85  along the members  81  in the Y-axis.  
         [0054]    The module M 4  is mounted to the cross-member  85  of module M 3 , hence, module M 3  moves module M 4  in the Y-axis. Module M 4  includes a pair of parallel side members  91  extend in the Z-axis and are connected to the cross-member  85  of module M 3  in a parallel, and spaced apart fashion. The actuator  1   c  of module M 4  is also mounted to the cross-member  85  of module M 3 . The actuator  1   c  is mounted to one face of the cross-member  85 , and the side members  91  are mounted to a different face of the cross-member  85 . Slide rails  7   c  are mounted to the side rails  91  to be in the Z-axis (and to be perpendicular to the slide rails  7   a  and  7   b ). Slides  9   c  are slidable along the slide rails  7   c : and the plate  61  (identical to the plate  31 ) extends between the side members  91  and is mounted to the slides  9   c  at its opposite ends. The rod  13   c  is connected to the plate  61  to move the plate along the members  91  in the Z-axis.  
         [0055]    Turning to FIG. 12, the control cables  17   a - c  from the actuators  1   a - 1   c  place the actuator controllers  15   a - c  in communication with the computer C. Instructions from the remote computer C are sent to the dedicated controllers  15   a - c  to move the respective positioning rod  13   a - c  along their respective slide rails  7   a - c.  In this configuration, the remote computer C can position the plate  61  of the unit  60 , and any object attached to the plate  61 , in a desired location in a three-dimensional Cartesian space, by directing each of the modules M 2 , M 3  and M 4  to move their respective positioning rods  13   a - c  to a desired position. The distance the plate  61  can translate in any given direction is only limited by the length of travel available from the module that provides that direction of travel in the unit  60 .  
         [0056]    The units  30  (FIGS.  5 - 8 ) and  60  (FIGS.  9 - 10 ) are modular units. Because the units are all constructed using the extruded members  3 , the units can be assembled together. A robotic assembly system or unit  100  is shown in FIG. 11 which includes the units  30  and  60 . The units  30  and  60  are positioned about a conveyer system  110 . In the unit  100 , a tray  112  moves along the conveyor to be positioned beneath the assembly  60 . The unit  30  is used to load product P onto the rake  31 . The unit  60  then moves a collector or gripper  114  which picks up the product P from the rake  31 , and then deposits the product P in openings in the tray  112 . Once full, the tray  112  is moved out from under the unit  60  by operation of the conveyor system  110 . As can be appreciated, the computer C moves the rake  31  of unit  30  so that it can be properly filled with parts. The computer C then operates the unit  60  to raise, lower, and mover the gripper  114  to pick up the product P from the rake  31  and then transport and deposit the product P on the tray  114 .  
         [0057]    In FIG. 13, a system or unit  200  is shown which includes several sub units, including the units  30  and  60 , a pair of adjacent conveyors  210  and  212 , and additional modules or units  220  and  240  (both of which are three-axis modules). The units  100  and  200  demonstrate how, using standard extrusions and interconnected linear actuators, separate units can be constructed, connected together, and integrated with each other to develop a production line in which product P is transported according to a predetermined pattern. Because the units are all made from the same parts, special pieces and special assembly techniques are not required. Hence, the cost and time to develop and build a unit, such as the unit  100  or  200  can be reduced.  
         [0058]    As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. For example, although modules are shown which move parts in a single axis or in three-axes are shown, it will be understood that a module can be produced using the extrusions and actuators to move a part in two axes. Additionally, the members from which the modules are made are all connected together at right angles. The members could also be connected together an acute or obtuse angles (as opposed to right angles), to move a part along a diagonal path. These examples are merely illustrative.