Abstract:
A gripper system having a pair of jaws operable in a first plane and having a central closure axis; each jaw including a finger member and finger tip member disposed on its distal end; and a gripper drive assembly for moving the jaws toward and away from each other; each finger member having a shaped inner contour for accommodating an object to be gripped; each finger tip member including an inner surface which generally aligns with the shaped inner contour for gripping a range of larger objects and an outer surface which generally aligns with the gripper central closure axis upon closure for gripping a range of smaller objects. Alternatively, each finger tip member may include a forcep element extending transversely to said plane.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved gripper system for gripping a large range of objects and for gripping in confined spaces and adapted for use in mobile robots. 
     BACKGROUND OF THE INVENTION 
     Mobile, remotely controlled robots are becoming increasingly popular for use by the military, SWAT units, and police and fire departments. The applicants&#39; TALON® robot, for example, includes an arm with an end effecter, several cameras, several antennas, and a deployable mast. Frequently the end effector is a gripper, e.g. a pair of jaws that can be opened and closed on command to grasp objects such as debris, hazardous material, unexploded ordinance and the like. The larger robots even have the capability to grip an injured, downed, person by some personal paraphernalia such as a shirt collar and drag them out of harm&#39;s way to safety. End effector grippers generally are designed to grasp objects within a defined size range. To grip objects larger or smaller than that size range, the present grippers must be removed and replaced with a gripper that has the desired size range capability. This requires an interruption in the availability of the mobile robot and can be dangerous and even life threatening in the circumstances in which these robots are frequently used. Another problem often encountered is the difficulty in using the grippers to reach into confined spaces and or grip very small objects such as, for example, a single wire in a bundle or inside a housing. Often this requires tipping the end of the gripper downwardly, often involving the arm, about the pitch axis of the jaws to gain access to the confined space and/or grip a wire. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to provide an improved gripper system. 
     It is a further object of this invention to provide such an improved gripper system particularly suited for mobile robots. 
     It is a further object of this invention to provide such an improved gripper system which is compliant and able to accommodate a broad range of shapes and sizes. 
     It is a further object of this invention to provide such an improved gripper system which is scalable as well to even larger and smaller size ranges. 
     It is a further object of this invention to provide such an improved gripper system which is lighter, stronger and less expensive. 
     It is a further object of this invention to provide such an improved gripper system with increased dexterity and able to perform in confined spaces. 
     It is a further object of this invention to provide such an improved gripper system which is able to perform in confined spaces without relying wholly on pitch axis rotation. 
     The invention results from the realization that a more universal, compliant gripper system, for use in a mobile robot, for example, which can grip objects over a wide size range can be achieved with a pair of jaws operable in a first plane and having a central closure axis, each jaw having a finger member and a finger tip member disposed at its distal end and a gripper drive assembly for moving the jaws toward and away from each other. Each finger member has a curved inner contour for accommodating an object to be gripped and each finger tip member includes an inner surface including an inner dihedral defining the sections which generally align with the curved inner contour for gripping a range of larger objects and an outer surface having an outer dihedral defining sections which generally align with the gripper central axis upon closure for gripping a range of smaller objects. A forcep element may extend from each finger tip member transversely to the first plane for gripping items. 
     The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives. 
     This invention features a gripper system including a pair of jaws operable in a first plane and having a central closure axis, each jaw including a finger member and finger tip member disposed on its distal end and a gripper drive assembly for moving the jaws toward and away from each other. Each finger member has a shaped inner contour for accommodating an object to be gripped; each finger tip member includes an inner surface which generally aligns with the shaped inner contour for gripping a range of larger objects and an outer surface which generally aligns with the gripper central closure axis upon closure for gripping a range of smaller objects. 
     In preferred embodiments the inner surface may include an inner dihedral defining sections which genially align with the shaped inner contour. The outer surface may include an outer dihedral defining sections which generally align with the gripper central axis. The inner surface may be curved. The outer surface may be curved. The inner contour may be curved. The inner contour may be a fair curve. The inner contour may be a circular arc. Each the finger member may include a pivot device for pivotably mounting the finger tip member to the associated finger member. Each inner surface may include an inner dihedral defining sections which generally align with the shaped inner contour and the pivot device may be disposed proximate the apex of the dihedral. Each jaw may include a stop mechanism for limiting rotation of each finger tip member about the pivot device. Each stop mechanism may include a fork device on one of the members and a stop device on the other. Each finger member may include a pair of spaced plates fastened together by a plurality of spacers. Each finger member and finger tip member may be fixed together. The gripper drive assembly may include a worm gear fixed to the proximal end of each jaw and a worm for rotating both worm gears. Each finger tip member may include a forcep element extending transversely to the first plane 
     The invention also features a gripper system including a pair of jaws operable in a first plane and having a central closure axis, each jaw includes a finger member and finger tip member disposed on its distal end. There is a gripper drive assembly for moving the jaws toward and away from each other. Each finger tip member includes a forcep element extending transversely to the first plane. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: 
         FIG. 1  is a schematic block diagram of a prior art mobile robot system having an end effector gripper on the end of an articulated arm; 
         FIG. 2  is a three dimensional, partially exploded, diagrammatic view of a gripper system according to this invention; 
         FIG. 3  is a top plan diagrammatic view of the gripper system of  FIG. 2  in the filly open position; 
         FIG. 4  is a top plan diagrammatic view of the gripper system of  FIG. 2  in the fully closed position; 
         FIG. 5  is an exploded three dimensional view of one jaw of the gripper system of  FIGS. 2-4 ; 
         FIG. 6  is a three dimensional diagrammatic view of a gripper system in the fully closed position with finger tips having transverse forcep elements; 
         FIG. 7  is a is a three dimensional diagrammatic view of another embodiment of a gripper system in the filly closed position having transverse forcep elements; 
         FIG. 8  is an exploded three dimensional view of the gripper device assembly of  FIGS. 3 ,  4 ,  6  and  7 ; 
         FIGS. 9A-F  are a sequence of diagrammatic plan views showing the gripper system of this invention grasping a number of circular objects of decreasing size; and 
         FIGS. 10A-F  are a sequence of diagrammatic plan views showing the gripper system of this invention grasping a number of rectangular objects of decreasing size. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer. 
       FIG. 1  shows a mobile, remotely controlled robot  10  driven by tracks  12   a  and  12   b  in accordance with one particular example of a robot in accordance with the subject invention. Robot  10  includes deployable mast  14 , camera  16 , light  18 , antennas  20   a  and  20   b , and arm assembly  22 . Arm assembly  22  includes lower arm  24  and upper arm  26 . Lower arm  24  is able to pitch up and down but it does not turn. Upper arm  26  pitches with respect to lower arm  24  and is driven by chain drive  28  extending along lower arm  24 . Microphone  30  is on upper arm  26  as is end effector  32  which rotates via wrist  34 . Camera  36  is typically aimed at end effector  32 . Operator control unit  40  is used to wirelessly control robot  10  as is known in the art. The various images captured by the cameras of the robot may be displayed on view screen  41 . 
     End effector  32 ,  FIG. 1 , may be replaced by an improved gripper system according to this invention, such as gripper system  40 ,  FIG. 2 . Gripper system  40  includes two jaws  42 ,  44 , each including a finger member,  46 ,  48 , and fingertip member  50 ,  52 , respectively. Each finger member  46 ,  48  is formed of a pair of spaced arms  54 ,  56 , and  58 ,  60 , respectively, which are spaced apart and fixed together by spacers  62 ,  64 , and  66 ,  68 , respectively. This makes finger members  46 ,  48 , strong but extremely light. For further weight reduction finger tip members  50 ,  52  may have hollowed out portions as shown at  89  on finger tip member  52 . At the proximal end of each arm  54 ,  56 ,  58  and  60  are rectangular holes  70  which engage with shouldered portions  72  of drive shafts  74  of gripper drive assembly  75  and may be held in place by screws  76 . Each finger tip member  52  is fastened at pins  78 ,  80  to the distal ends of arms  54 ,  56  and  58  and  60 , respectively. Each finger tip member has an inner surface  82 ,  84  and an outer surface  86  and  88 . 
     Jaws  42  and  44 ,  FIG. 3 , have a shaped inner contour  90 ,  92  for accommodating an object to be gripped, such as object  94 . Inner contours  90 ,  92  may be fair curves or other shapes or as shown in  FIG. 3  they may be circular arcs centered at point  96  at the center of the largest object  94  sought to be gripped. Fingertip members  50 ,  52  may have their inner surfaces  82 ,  84  formed as a curved surface as shown in phantom at  98  or they may, for example, be a dihedral surface defined by dihedral angle  100  which defines two sections  102  and  104 . Note that dihedral angles  100  may have their apices aligned with pivot pins  78 ,  80 , which may be on a diameter  150  of center  96 . Outer surfaces  86  and  88  may also be a curved surface as indicated at  106  or may also be a dihedral as indicated by dihedral angle  108  which defines dihedral sections  110  and  112 . Gripper drive assembly  75  drives jaws  42 ,  44  to open and close in the directions indicated by arrows  114  and  116  in the plane of operation  118  which may be defined by the plane of the paper. Preferably whatever their shape inner surfaces  82 ,  84  generally track along with the shapes  90 ,  92  or are generally tangential to the object  94 . 
     In  FIG. 3  gripper system  40  has its jaws  42 ,  44  open for gripping at 66° . In contrast in  FIG. 4 , gripper system  40  has its jaws  42 ,  44  closed so that the outer surfaces  86  and  88  of finger tip members  50 ,  52  meet at the gripper central axis  120  illustrating the facility for gripping very small objects as well. 
       FIG. 5  is an exploded view of jaw  42  including finger member  46  and finger tip member  50 . The spacers  62  and  64  that hold arms  54  and  56  together actually include spacer sleeves  130 ,  132  and mounting screws  134 ,  136  and  138  and  140 , respectively. A stop mechanism  141  may include spacer  132  slightly reduced in diameter and a recess  142  which is larger than the diameter of spacer member  132  and pin  78  may be a pivot pin, which pivots and holds  144  and  146  of arms  54  and  56 , respectively. In this way, finger tip member  50  and finger tip member  52  as well may rock slightly to make a more universally compliant surface for gripping a range of large and small objects. Spacer  132  thus functions as a stop and recess  142  is in the nature of a fork. The positions of these items, stop and fork, could be switched so that the stop is on finger tip member  50 ,  52  and the fork on finger members  46 ,  48 . Other implementations of stop mechanisms  141  may use other combinations. If it is desired that finger tip members  50 ,  52  be not pivotable then recess  142  and spacer bar member  132  will be closely dimensioned to prevent any rotation about pin  78 . Pin  78  may be preferably located on a diameter  150 ,  FIG. 3 , of the largest object  94  anticipated for gripping but it need not be so positioned. Referring again to  FIG. 5 , the one or both finger tip members  50 ,  52  may be provided with serrations, or some sort of improved gripping surface as indicated at  152 . 
     At times it is necessary and desirable to use the finger tip members  50 ,  52  to dip into a confined space, for example, an electronic component housing to pull out a wire or two for clipping or other manipulation. Presently, in order to accomplish this either the entire upper arm  26  has to be moved in the pitch axis,  FIG. 1 , or perhaps gripper system  32  has to be moved in the pitch axis in order to accommodate such tasks. In order to avoid this the finger tip members  50   a ,  52   a , may be provided with forcep elements  160 ,  162 ,  FIG. 6 , which extend transversely to the plane of operation, see plane  118 ,  FIG. 3 , to grip such items with a minimum of pitch rotation required. The forcep elements need not be accompanied by the inner surface and outer surface constructions as shown in  FIG. 6 , for as shown in  FIG. 7  finger tip members  50   b ,  52   b , may have forcep elements  160   b , and  162   b  without those outer and inner surfaces shown in  FIG. 6 . 
     Gripper drive assembly  75 ,  FIG. 8 , includes housing  180  with cover  182  secured by screws  184  and a collar  186 . Worm drive shaft  187  passes through collar  186  to engage worm  188 . Worm  188  drives worm gears  190 ,  192  which are held on shafts  74  by “C” rings  194  and keyed to rotate with shafts  74  by means of key ways  195  on worm gears  192 ,  194  which engage with keys  197  on shafts  74 . 
     The facility of gripper system  40  according to this invention to grasp a large range of different size objects and different shaped objects is shown in  FIGS. 9A-F  and  10 A-F.  FIGS. 9A-F  show a sequence of applications of gripper system  40  to smaller and smaller circular objects, starting with, for example, a five inch diameter circular object  200  and decreasing through four inch diameter object  202 , three inch diameter object  204 , two inch diameter object  206 , one inch diameter object  208  and a half inch diameter  210 . Note that in  FIGS. 9A and 9B  the object is gripped by the inner surfaces  82 ,  84 . In  FIGS. 9C and 9D  the object is gripped by the inner contours  90 ,  92  and in  FIGS. 9E and 9F  the object is gripped by the outer surfaces  86 ,  88 . When the object is a rectangular body, such as shown in  FIGS. 10A-F  the same transition from gripping with the inner surfaces  82 ,  84  in  FIGS. 10A and 10B  to the gripping by contours  90 , and  92  but in conjunction with outer surfaces  82 , and  84 , in  FIGS. 10C and 10D , and with the outer surfaces  86 ,  88  in  FIGS. 10E and 10F . In this way the improved gripper system according to this invention accommodates not only objects of a wide variety of sizes but also of many different shapes. 
     Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments. 
     In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended. 
     Other embodiments will occur to those skilled in the art and are within the following claims.