Abstract:
An end effector for a mobile, remotely controlled robot includes first and second fingers; each finger fixed to a gear segment for rotation therewith; and a drive subsystem driving the gear segments and the associated fingers between open and closed positions.

Description:
FIELD OF THE INVENTION 
     This invention relates to a mobile, remotely controlled robot, and more particularly to such a mobile, remotely controlled robot with an improved end effector gripper. 
     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. One problem with large, strong grippers is that larger gears are needed to drive the gripper fingers with sufficient torque to realize a strong grip force. But larger gears translate to larger end effector units and significant increase in their weight. Another issue with present grippers is that the gripper fingers can sag or twist on their pivot axis causing premature failure and less than optimum gripping function. Yet another issue with end effector grippers is the need to keep the motor/reduction gear package small and compact to keep down the size of the end effector unit, while still providing a strong grip force and rapid gripper closing/opening. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to provide an improved end effector gripper for a mobile, remotely controlled robot. 
     It is a further object of this invention to provide such an improved end effector gripper for a mobile, remotely controlled robot which provides increased gripping torque (grip force). 
     It is a further object of this invention to provide such an improved end effector gripper for a mobile, remotely controlled robot which provides increased gripping torque without the accompanying typical increase in size and weight. 
     It is a further object of this invention to provide such an improved end effector gripper for a mobile, remotely controlled robot which provides increased gripping torque yet maintains a sufficient gripper range of action and speed of operation. 
     It is a further object of this invention to provide such an improved end effector gripper for a mobile, remotely controlled robot which reduces sag and twisting of the gripper fingers relative to their pivot axis. 
     It is a further object of this invention to provide such an improved end effector gripper for a mobile, remotely controlled robot which reduces the extent (axial length) of the end effector unit to facilitate co-axial alignment with robot wrist axis. 
     It is a further object of this invention to provide such an improved end effector gripper for a mobile, remotely controlled robot having a folded construction which allows the end effector to be mounted co-axially with the robot arm and wrist for enabling in-line wrist rotation with axial compactness. 
     The invention results from the realization that a strong yet compact end effector for a mobile, remotely controlled robot can be achieved with a drive subsystem that drives gear segments fixed to respective fingers for increasing the torque applied through the fingers without the normally associated increase in size; and further that a bilateral pivot pin can improve consistency and rigidity of finger operation; and that the end effector compactness can be further improved using a folded motor gear reducer drive (package). 
     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 an end effector for a mobile, remotely controlled robot including first and second fingers, each finger fixed to a gear segment for rotation therewith, and a drive subsystem driving the gear segments and the associated fingers between open and closed positions. 
     In a preferred embodiment the fingers may be gripper fingers. The gear segments may be worm gear segments and the drive subsystem may further include a worm for driving the gear segments. The gripper finger may be fixed to its associated worm gear segment by a pivot pin on each worm gear segment. Each pivot pin may extend from both sides of its associated gear segment and each gripper finger may have at its proximal end a yoke with upper and lower spaced arms for fixedly engaging the associated pivot pin on either side of its gear segment. The worm gear segments may be the same size. The worm gear segment may be 60°. The drive subsystem may include a folded motor and gear reducer assembly. The drive subsystem may include a drive gear, the motor and gear reducer may be in side by side relationship and a first gear on the motor may drive a second gear on one end of the gear reducer and a third gear on the other end of the gear reducer may drive the drive gear. The worm may drive the worm gear segments equally, synchronously 
     This invention also features an end effector for a mobile, remotely controlled robot including first and second fingers, each finger fixed to a worm gear segment for rotation therewith. A worm drives the worm gear segments and the associated fingers between open and closed positions. A folded motor and gear reducer gear assembly drives the worm; the worm includes a drive gear. The motor and gear reducer are in side by side relationship. A first gear on the motor drives a second gear on one end of the gear reducer and a third gear on the other end of the gear reducer drives the drive gear of the worm. 
    
    
     
       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  a schematic three-dimensional view of conventional mobile, remotely controlled robot including upper and lower arms and an end effector gripper; 
         FIG. 2  is a schematic three-dimensional view of an end effector gripper according to this invention; 
         FIG. 3  is a schematic top, plan view of the gear drive mechanism for the gripper fingers of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view along lines  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view along lines  5 - 5  of  FIG. 3  showing the motor and gear reducer drive package in a folded relationship with the final gear and worm; 
         FIG. 6  is a simplified exploded three dimensional view of the folded motor and gear reducer drive package; 
         FIG. 7  is a schematic top, plan view of a worm gear segment of  FIG. 3 ; 
         FIG. 8  is a three dimensional view of the worm gear segment of  FIG. 7  showing the pivot pin extending from both sides; and 
         FIG. 9  is a schematic top, plan view of the gripper fingers opened to a full 120°. 
     
    
    
     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 gripper  32  which rotates via wrist  34 . Gripper camera  36  is typically aimed at gripper  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 . 
     An end effector  60 ,  FIG. 2 , according to this invention includes a pair of fingers  62 ,  64  which may include gripper pads  66 ,  68  on their inside ends. End effector  60  is here shown as a gripper, as an example only, as any number of other functions may be accomplished, e.g. scissors, magnetic holder . . . . Each finger  62  and  64  has fixed to its proximal end a yoke  70 ,  72  each having two spaced arms  74 ,  76 ,  78  and  80  (not shown in  FIG. 2 ). Arms  74  and  76  are attached to opposite ends of pivot pin  82  passing through end effector housing unit  84 . Arms  78  and  80  are fixed to opposite ends of pivot pin  86  also passing through housing unit  84 . 
     Inside housing unit  84 ,  FIG. 3 , are a pair of gear segments  88 ,  90  which in this case are shown as worm gear segments driven by worm  92  fixed to and driven by shaft  94 . In this embodiment worm  92  drives each of the segments  88  and  90  synchronously equally so that fingers  62  and  64  open and close symmetrically, but this is not a necessary limitation of the invention. By using gear segments instead of fill gears the full torque providable by a gear of a given radius may be provided without requiring the space for a complete gear. That is, gear  90 , for example, may be a 60° sector with a 3.125 inch pitch diameter. That means the radius of the gear is roughly half of 3.125 inches or approximately an inch and a half. Thus the housing need accommodate only a little more than an inch and a half for each gear segment plus the worm gear. If the full gear were used then the full 3.125 inches would have to be provided for each worm gear, that plus the worm would require a housing of 6 or 7 inches or more. So the torque provided by such a large gear is available without providing for a concomitant larger housing. Also fixed to shaft  94  is drive gear  96  which may be a spur gear for example. Pivot pins  82  and  86 ,  FIG. 4 , are supported in bearings  100 ,  102 , and  104 ,  106 , respectively, and are fixed to rotate with gear segments  88  and  90 . Also contained in housing or unit  84  are folded motor and gear reducer sub-assembly  110  (see  FIG. 6 ) including motor  112  and gear reducer  114  disposed in adjacent side by side relationship in housing  84 . Each of pivot pins  82  and  86  extend beyond their respective gear segments  88  and  90  and housing  84  in both directions in order to attach to the arms  74  and  76  of yoke  70  and arms  78  and  80  of yoke  72 . In this way yokes  70 ,  72  and their fingers  62  and  64  as well as grips  66  and  68  at their distal ends are kept more rigid and more accurately aligned even under heavy load. 
     Gear reducer  114 ,  FIG. 5 , includes on shaft  119  a gear  118  at one end which engages with gear  122  on shaft  124  of motor  112  and a second gear  120  on the other end on shaft  121  which engages with drive gear  96  on shaft  94  to drive worm  92 . Gear  118 , on shaft  119 ,  FIG. 6 , of gear reducer  114  meshes with gear  122  on output shaft  124  of motor  112 . The ends of motor  112  and gear reducer  114  are mounted in transfer case  116  having a cover  128 . The various gears in this folded drive sub assembly are shown as spur gears, but this is only for a preferred embodiment. This folding of the motor and gear reducer in side by side relationship and further folding of the motor-reducer with respect to the drive worm makes the end effector housing or unit much more compact. The folding of the end effector/gripper construction (for compactness, especially axially) allows the end effector/gripper to be mounted co-axially with the robot arm wrist thus achieving in-line rotation (with respect to wrist rotation axis) without making the whole thing overly long. 
     The segmental structure of the gear segments  88  and  90  are shown more specifically in  FIG. 7 , where gear segment  88  is shown enlarged and in some detail.  FIG. 8  shows the same gear segment  88  in a three dimensional view where the bilateral extension of pivot pin  82  can be seen. Gear  90  and pivot pin  86  are constructed in exactly the same way. Although the use of a gear segment instead of a full gear restricts the rotational range of the device, it can be seen,  FIG. 9 , that with merely a 60° sector the fingers  62  and  64  can be opened to a full 120°: a full functional range for the grippers. 
     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.