Abstract:
A universal robotic end effector for use with a robot system is disclosed. The end effector is suited for transport by a high speed apparatus and, upon delivery to its destination, the end effector is capable of disengaging from the transport device. Once disengaged, the end effector is capable of independent operation. The end effector may rely on self-contained power and control signals, or may receive them from any workstation to which it is docked and locked, or from a remote source. Finally, the end effector is capable of reacquiring the moving transport device when it is ready to be moved to a new workstation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Technical field  
           [0002]    The present invention relates generally to the field of robotics. In particular, this invention relates to a robotic device, system and method having a universal robotic end effector for mating to a workpiece.  
           [0003]    2. Related Art  
           [0004]    The field of robotics is a rapidly developing area of technology. Robotic systems are continually being adapted to operate in new market niches, and to operate at higher speeds in existing production areas. Robotics will continue to play an increasingly important role in the economic viability of existing, as well as emerging, technologies. For example, manufacture of miniature assemblies incorporating MEMS (Micro-Electro-Mechanics) devices is tedious and extremely difficult to perform efficiently for even a skilled person. Similarly repetitive and labor intensive tasks are present in many other industries, including photonics, laboratory automation, electronics assembly, food processing, material handling, and pouch singulation. Inherent in each of these processes is the need for a robotic end effector which can be repeatedly transported via high speed transfer systems, and which can perform high precision operations at the destinations to which it is delivered.  
           [0005]    In general, the related art has provided a variety of robotic devices with which to address these constraints. For instance, in an assembly process, a standard robotic solution usually includes the use of detailed part geometry to align the assembly process using a device known in the art as a remote center of compliance device. One drawback of this approach is that it typically requires modifications or design changes to the product to be assembled.  
           [0006]    Other solutions include the use of machine vision systems to provide positional feedback to the assembly process. This approach is expensive, and also suffers from the inherent drawback that portions of the product under assembly frequently obstruct the view of the vision system.  
           [0007]    Another solution utilizes a mechanical closed loop robotic arm end effector positioning system. This approach, described in U.S. Pat. No. 4,919,586, granted Apr. 24, 1990 to Dr. Stephen Derby, discloses the operation of a larger, low precision robot to move a smaller, more precise robot into position to perform assembly tasks. This approach uses a docking process which involves forcing three legs of the smaller robotic device into three matching openings in a work table surface. This docking process achieves a very high precision between the robotic device and the assembly work station.  
           [0008]    There are limitations to this device, however, because the larger robot must hold the smaller robotic device in place while the smaller robotic device performs its assigned tasks. Thus, a single large robot system cannot service a plurality of smaller robots simultaneously, which is a necessary attribute if dramatic increases in process throughput are desired. Also, it is difficult to coordinate the larger robotic system with an incrementally moving work station.  
           [0009]    Therefore, a novel apparatus which is less complex and costly than presently available robotic systems is believed clearly desirable. Furthermore, any such novel apparatus must provide increases in speed and throughput, while maintaining or increasing precision operation and assembly.  
         SUMMARY OF THE INVENTION  
         [0010]    As noted initially and more fully described herein, the the present invention solves these problems in the related art by providing a universal robotic end effector device suitable for use with a robot system. The robotic device typically functions as a material handling instrument, although other embodiments are readily available.  
           [0011]    The robotic device is capable of performing any task which requires manipulation or processing of a workpiece and which may be performed by a robot. The robotic device receives its control signals and power from several sources, namely, the workpiece, the workstation, or a remote command center. Alternatively, the robotic device may be autonomous, with its own microprocessor. A smaller robot may be part of the robotic device. This smaller robot may perform the required operations on the workpiece while the larger robotic device remains attached to it. The larger robotic device may also leave the smaller robot docked and locked to the workstation and move to another workstation to relocate a second smaller robot. While docked and locked, the smaller robot and its associated workpiece, or workstation, may be indexed to a new location, either by machine or by hand. Operations by the smaller robot can thus continue while in transit. Finally, the larger robot or an automation system may reacquire the robotic device at either its original location or at some new location. Use of a coupling mechanism (e.g., a clutch and brake combination) on each robotic device may be employed to create a desired acceleration, deceleration, or other controlled trajectory speed matching scheme when a robotic device is picked or placed by its robot system or other transporting means.  
           [0012]    In a first general aspect, the present invention presents a robotic device, suitable for mating a docking end effector to a workstation, comprising: at least one positioning member; a system for coupling said docking end effector to said workstation; and an exchange mechanism operationally coupled to the docking end effector and to a transport mechanism.  
           [0013]    In a second general aspect, the present invention presents a device comprising: at least one positioning member; an exchange mechanism to operationally couple a docking end effector to a transport mechanism; a supply of motive power operationally attached to the docking end effector; and a control system operationally attached to the docking end effector, said control system for controlling actions of the docking end effector.  
           [0014]    In a third general aspect, the present invention presents a device comprising: at least one positioning member; a system for coupling a docking end effector to a workstation; a mechanism to operationally couple the docking end effector to the workpiece; a control system operatively attached to the docking end effector, said control system adapted to control the actions of the docking end effector; and a device for releasably attaching the docking end effector to a transport device.  
           [0015]    In a fourth general aspect, the present invention presents a mechanical closed loop system for translationally locating along X, Y, Z axes and rotationally locating about each of said X, Y, Z axes the distal end of a docking end effector relative to a workpiece, the docking end effector end having an independently operated robotic manipulator affixed thereto for performance of precision tasks on a workpiece positioned on said fixture, said system comprising: an assembly mountable to the docking end effector, said assembly having a compliant member and a first positioning member connected to the compliant member, said first positioning member including a first docking means; a second positioning member associated with the workpiece, said second positioning member including a second docking means; said first docking means and said second docking means including: (i) a first positioning leg connected to one of said first positioning member and said second positioning member and a first positioning port associated with the other of said first positioning member and said second positioning member, said first positioning port having a tapered lead-in configured to engagably receive and position said first positioning leg&#39;s free end as the docking end effector attains a target position relative to the workpiece; (ii) a second positioning leg connected to one of said first positioning member and said second positioning member and a second positioning port associated with the other of said first positioning member and said second positioning member, said second positioning port having a tapered lead-in configured to engagably receive and position said second positioning leg&#39;s free end as the docking end effector attains its target position relative to the workpiece; (iii) a third positioning leg connected to one of said first positioning member and said second positioning member, said third positioning leg being sized and configured such that its free end engages the other of said first positioning member and said second positioning member when the docking end effector attains its target position relative to the workpiece; said compliant member providing rotational and translational freedom of movement for said first docking means to precisely position itself with respect to and interlock with said second docking means to ensure that the docking end effector attains the desired three-dimensional coordinates and three-dimensional rotational orientation relative to the workpiece; said robotic manipulator being located intermediate said first positioning member and said second positioning member when said first docking means and said second docking means are interlocked, whereby docking of said first and second positioning members produces a translational and rotational six-degree of freedom mechanical closed loop reference frame which separates operation of the independent robotic manipulator from gross movement inaccuracies and vibrations of a docking end effector transport system; and locking means located on the docking end effector, said locking means adapted to accept a corresponding locking means located on the workpiece.  
           [0016]    In a fifth general aspect, the present invention presents a method for performing robotic actions on a workpiece, said method comprising: providing at least one workstation; providing at least one workpiece on said workstation; providing at least one robotic device; providing a transport system for said robotic device; transporting said robotic device to said workstation; depositing said robotic device at said workstation; coupling said robotic device to said workpiece; commanding said robotic device to act on said workpiece; and removing said first robotic device from said workstation.  
           [0017]    In a sixth general aspect, the invention presents a method for performing robotic actions on a workpiece, said method comprising: providing at least one workstation; providing at least one workpiece on said workstation; providing at least one robotic device; providing a transport system for said robotic device; coupling said robotic device to said transport system; transporting said robotic device to said workstation; depositing said robotic device at said workstation; commanding said robotic device to act on said workpiece; and removing said first robotic device from said workstation.  
           [0018]    In a seventh general aspect, the present invention presents a method for utilizing a first transportable robotic device in a system where a transporting device positions the first transportable robotic device, said method comprising: providing at least one transportable robotic device; providing a system for the first transportable robotic device to removably attach to the transporting device; providing a system for the first transportable robotic device to dock with a workstation; and providing at least one effecting device on said first transportable robotic device.  
           [0019]    In an eighth general aspect, the present invention presents a method for performing robotic actions on a workpiece, said method comprising: providing a workstation for operationally mounting said workpiece; transporting a first robotic device to said workstation; docking said first robotic device to said workstation; locking said first robotic device to said workstation; operationally connecting said first robotic device to said workpiece; commanding said first robotic device to act on said workpiece; and removing said first robotic device from said workstation.  
           [0020]    The foregoing and other objects, features and advantages of the invention will be apparent in the following and more particular description of the preferred embodiments of the invention as illustrated in the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    The embodiments of this invention will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein:  
         [0022]    [0022]FIG. 1 is an overall perspective view of a docking robotic end effector of one embodiment of the present invention;  
         [0023]    [0023]FIG. 2 is a detail view of a docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0024]    [0024]FIG. 3 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0025]    [0025]FIG. 4 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0026]    [0026]FIG. 5 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0027]    [0027]FIG. 6 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0028]    [0028]FIG. 7 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0029]    [0029]FIG. 8 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0030]    [0030]FIG. 9 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0031]    [0031]FIG. 10 is a detail view of an alternative docking mechanism for a docking robotic end effector of an embodiment of the present invention;  
         [0032]    [0032]FIG. 11A is a plan view of a portion of the docking robotic end effector device of an embodiment of the present invention employing a quick release brake mechanism;  
         [0033]    [0033]FIG. 11B is another plan view of a portion of the docking robotic end effector device of an embodiment of the present invention employing a quick release brake mechanism;  
         [0034]    [0034]FIG. 12A is a plan view of a portion of the docking robotic end effector device of an embodiment of the present invention employing a brake and roller coupling mechanism;  
         [0035]    [0035]FIG. 12B is another plan view of a portion of the docking robotic end effector device of an embodiment of the present invention employing a brake and roller coupling mechanism; and  
         [0036]    [0036]FIG. 13 is a perspective view of a laboratory automation embodiment with a multi-head tracked robot system capable of delivering, to numerous workstations, a plurality of the docking robotic end effector devices of an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]    Referring to the drawings, FIG. 1 illustrates a first embodiment of the present invention, that is, a universal robotic end effector  100 , suitable for use with a robot system capable of the high speed conveyance of a number of such robotic devices.  
         [0038]    In the embodiment depicted in FIG. 1, a robotic end effector  100  is shown having three legs  110 ,  111 ,  112 , and an attached robotic device  140 . The legs  110 ,  111 ,  112 , and the robotic device  140 , are operationally attached to a base plate  120 . Located at the distal end of each leg  110 ,  111 ,  112 , is a ball  130  which facilitates a docking operation. The docking operation operationally attaches the robotic end effector  100  to a workstation  190 . The workstation  190  includes a first docking plate  170  and a flat docking plate  180 . An exchange mechanism  145  facilitates the operational coupling of the robotic end effector  100  to a transport mechanism  150  such as, inter alia, a transfer robot, man-portable carry handle, etc. The distal ends of the three legs  110 ,  111 ,  112 , are oriented so that they contact the first docking plate  170  and the flat docking plate  180 . Two of the legs  110 ,  112  are oriented so they are received in a cone-shaped hole  175  and a slot  177 , respectively, of the first docking plate  170 . A total of six spring-loaded balls  220  (FIG. 2) is required to properly dock the three-legged robotic end effector  100 .  
         [0039]    Referring now to FIG. 2, a detailed view of a portion of the docking mechanism is shown. The docking operation will be first described with respect to leg  110 . Note that only a single configuration employing two spring-loaded balls  220  is depicted in FIG. 2. This is done for the sake of clarity. The number of spring-loaded balls will vary from one to three, depending on which leg  110 ,  111 ,  112  docking station is described.  
         [0040]    Now, during the docking operation, the ball  130  of leg  110  is aligned with, and inserted into, cone-shaped hole  175 . The cone-shaped hole  175  is surrounded by three spring-loaded balls  220 , positioned equidistantly around the cone-shaped hole  175 . Each of the three spring-loaded balls  220  presses against an indentation  160  on the leg  110 . The spatial relationship, between the diameter of the leg  110  at the inner radius of the indentation  160  and the location of each spring-loaded ball  220  when its associated spring  230  is compressed by the leg  110 , is such that the compressive force exerted on the leg  110  by each ball  220  firmly holds the leg  110  in place.  
         [0041]    Referring again to FIGS. 1 and 2, the docking operation with respect to leg  112  will be explained. Leg  112  is received in slot  177  of first docking plate  170 . Adjacent slot  177  are two spring-loaded balls  220 , which are positioned so that their line of action is perpendicular to the sides of slot  177 .  
         [0042]    Finally, with respect to leg  111 , the flat docking plate  180  receives leg  111  on a flat spot  176  located adjacent a single spring-loaded ball  220 .  
         [0043]    In each arrangement related to the docking of legs  110 ,  111 ,  112 , the spring-loaded balls  220  assist in the docking process by guiding the balls of the docking legs  110 ,  111 ,  112  into the neighborhood of the docking fixture (i.e., slot  177 , conical-shaped hole  175 , or flat spot  176 ). This approach also has the added benefit of reducing wear and tear on the equipment which results from normal operation.  
         [0044]    An alternative docking arrangement is depicted in FIG. 3. In this arrangement, the six spring-loaded balls  220  of FIG. 2 are replaced by six spring-loaded rollers  330 . The ball  130  on the leg  110  is fixedly emplaced by spring-loaded rollers  330  in the same manner as described for the spring-loaded balls  220  supra. Each of the six spring-loaded rollers  330  is attached to a corresponding spring  320 , which is in turn connected to a fixture  310  of the workstation  190  (FIG. 1).  
         [0045]    A second alternative docking arrangement is depicted in FIG. 4. In this arrangement, the six spring-loaded balls  220  of FIG. 2 are replaced by a plurality of magnets  430 . Thus, each of the three docking legs  110 ,  111 ,  112  is guided to and held by a magnet  430 , which is mounted on each of the three docking legs  110 ,  111 ,  112 , and which aligns with one of three corresponding metal plates  420 . Each of the three metal plates  420  is mounted to the workstation  190  and is adjacent a docking fixture (i.e., slot  177 , conical-shaped hole  175 , or flat spot  176  in FIG. 1). Alternatively, the magnets  430  can be mounted on either each metal plate  420  or in each docking fixture (i.e., slot  177 , conical-shaped hole  175 , or flat spot  176 , as shown in FIG. 1).  
         [0046]    [0046]FIG. 5 represents an embodiment similar to FIG. 4, but with the metal plate  420  of FIG. 4 now replaced by an electromagnet  520 . The electromagnet  520  is mounted to a fixture  510 . The functions, and alternative configurations, of this embodiment are similar to that described in the previous paragraph pertaining to FIG. 4.  
         [0047]    Another docking and locking configuration is illustrated in FIG. 6. This configuration utilizes a planar latching mechanism  600  which comprises a latch spring  640 , a latch pivot  650 , a latch arm  630 , and a latch interlock  620 . The latch spring  640 , latch pivot  650 , and latch arm  630  are attached to each of the three docking legs  110 ,  111 ,  112  (FIG. 1). The latch interlock  620  is attached to the workpiece  610 . The latching mechanism  600  can be operated entirely via mechanical means, or it may utilize remotely controlled electromechanical means (e.g., a solenoid). FIG. 6 shows the latched state, while FIG. 7 shows the unlatched state.  
         [0048]    Referring now to FIG. 8, each of the three docking legs  110 ,  111 ,  112  (FIG. 1) is further locked in position by a rotating latch  810 . A rotating latch is operationally attached to each of the three docking legs  110 ,  111 ,  112  (FIG. 1). The rotating latch  810  operationally engages a latching element  830  characterized by a T-shaped vertical cross section. The head  820  of latching element  830  is removably engaged by a latching slot  920  (FIG. 9) when rotating latch  810  is rotated. An overhead view of this latching arrangement is shown in FIG. 9.  
         [0049]    The above described embodiments could be reversed. For example, FIG. 10 depicts a cone-shaped docking feature located on one leg  1010  (of the three docking legs  110 ,  111 ,  112  of FIG. 1). The surface of the workstation  1050  includes a guide ball  1030  to assist in the docking process. The guide ball  1030  is mounted on a ball pedestal  1040  attached to the workstation  1050 .  
         [0050]    One of the features the universal robotic end effector  100  of the present invention is its suitability for use with a robot system capable of the high speed conveyance of a number of such robotic devices. This is due in large part to the ability of the robotic device to engage and disengage a moving transport means.  
         [0051]    A quick-release brake mechanism  1100  is one embodiment which provides the robotic device with the ability to engage and disengage a moving transport means (e.g., a cable). The head  1120  of the quick-release brake  1100  shown in FIGS. 11A and 11B is operationally attached via lever arm  1130  to either the robotic device itself, or to a truck or carrier which carries the robotic device. The quick-release brake  1100  provides friction contact between a main transport cable  1150 , which transports the robotic device, and the truck or robotic device itself. A wheel  1160  is incorporated for ease of movement of the robotic device.  
         [0052]    In operation, as depicted in FIG. 11B, downward motion on a lever arm  1130  releases the brake pressure on the transport cable  1150  allowing the head  1120  to move independent of the transport cable  1150 . The downward motion is initiated when unload arm  1180  contacts wheel  1160 .  
         [0053]    Alternatively, a belt drive system can be employed with a brake and roller system  1200  as shown in FIGS. 12A and 12B. The belt drive system requires that the head  1205  be supported by an overhead track via roller truck  1230 . The head is propelled by a drive belt  1240 . As the head  1205  enters the pulley  1270 , the wheel  1260  lowers the drive engagement device as it releases the brake  1250 . Friction in the wheel  1260  keeps the head  1205  moving forward when not restrained, at which time the wheel  1260  turns freely. After being released, the brake  1250  engages the belt in the opposite manner.  
         [0054]    Finally, a laboratory automation scheme, utilizing a plurality of robotic end effectors of the present invention, is represented by FIG. 13. In FIG. 13, the feet  1335  of the robotic device  1330  are docked to a tray  1320  of a plurality of wells  1325 . The tray  1320  be one of a plurality of trays situated in a pallet (not shown). The robotic devices  1330  will dock to the tray  1320  by mating docking pins  1345  to docking holes  1340 . Once the robotic device  1330  or devices have docked to the tray  1320  or pallet, the robotic devices  1330  can dispense simultaneously into the wells  1325 . The robotic devices  1330  are then refilled on the opposite side of the multi-head tracked robotic system  1300 . The multi-head tracked robotic system  1300  is further disclosed in U.S. application Ser. No. 60/195,065, filed Apr. 5, 2000, which application is hereby incorporated by reference.  
         [0055]    The foregoing and other objects, features and advantages of the invention will be apparent in the following and more particular description of the preferred embodiments of the invention as illustrated in the accompanying drawings.