Abstract:
An end effector controller that is gripped by an operator in one hand, including a pistol-grip housing configured to fit in the palm of an operator&#39;s hand when gripped and having mounted thereon a plurality of switching mechanisms with pivoting, dual-acting switch triggers each configured for independent actuation by multiple fingers of the hand when said controller is gripped, and a method for controlling a robotic end effector remotely using the operator hand-gripped controller, the method including switching between preset operating modes of the end effector using a single, control input element, easily actuated by a finger in the operator&#39;s gripping hand; and providing continuous fine adjustment between preset modes using a second, control input element also easily actuated by a finger on the operator&#39;s gripping hand.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of prior U.S. Provisional Patent Application Ser. No. 61/401,432, filed Aug. 11, 2010 by Daniel Greeley et al. for PISTOL-GRIP FOR INTUITIVE CONTROL OF A ROBOTIC OR VIRTUAL HAND, which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to controllers for teleoperating end effectors in real and virtual environments. More particularly, the present invention relates to a pistol-grip controller that comfortably and intuitively translates movement of a user-gripped controller into corresponding movements of an end effector and wherein the actuation of switches on the controller logically maps to different functionalities on an end effector. 
     BACKGROUND OF THE INVENTION 
     Currently, a variety of pistol-grip controllers exist for robotic end effectors. These controllers exist in many shapes, from joysticks to gloves, and with a variety of number and type of switching mechanisms. One type of known controller presents one or more discrete button switches or the like on a keypad or the like, to produce a desired action of the end effector. Another type of controller designed for a more intuitive control couples the controls to the user&#39;s hand by means of a glove or Velcro® straps. A drawback of such glove and strap-on devices is that they are not readily placed on the hand (“donned”) or removed from the operator&#39;s hand (“doffed”). 
     As one example, Penner, U.S. Pat. No. 4,905,001, discloses several different pistol-grip switch configurations that function as keyboard input devices. In one embodiment, the grip is designed to fit in an operator&#39;s hand while allowing each finger to actuate switches independently. Each finger actuates opposing switches using its proximal, nearest-to-palm, and distal, farthest-from-palm, segments or phalanges. 
     Shahoian et al., U.S. Pat. No. 6,184,868, describes a haptic feedback controller to control a parallel-jaw end effector remotely. The single button on the controller commands the position of the jaws. The controller also provides haptic feedback to the operator when the jaws grasp an object. This controller attaches to the end of a master arm that positions the arm to which the parallel jaws are attached. 
     Kraft, U.S. Pat. No. 7,623,945, describes a pistol-grip controller to mount onto a back-drivable robotic arm to teleoperate another arm with an end effector. The controller handle is curved to better fit an operator&#39;s hand. It also contains several switches accessible to the thumb. The types of switches are reconfigurable, but their thumb-accessible location remains the same. 
     Harper et al., U.S. Pat. No. 6,500,188, presents an ultrasonic surgery tool handle that has a single dual-action switch to control the opening and closing of a clamp arm of the instrument. The switch to control the clamp is mechanically linked to the clamp. It uses an up and down actuation to open and close the clamp. A thimble-shaped cavity allows for a finger to enter and actuate the switch. The switch must be actuated using the tip of the finger. Because the switch is mechanically linked to the clamp, the switch must stay depressed for the clamp to remain closed. 
     Gizis et al., U.S. Pub. No. US 2006/0229034 A1, created a remote-controlled-car controller with a dual-action trigger to govern the speed of the car. The pistol-grip controller has a trigger engaged by the pointer finger. The switch can be pulled towards or pushed away from the grip. 
     SUMMARY OF THE INVENTION 
     The present invention comprises the provision and use of an ergonomic, pistol-grip controller for the single-handed operation of a real or virtual end effector, e.g., a robotic hand with plural movable multi-link fingers. The controller includes a plurality of switching mechanisms, each with a preferably “C” or hook-shaped trigger exterior at the exterior of the controller. The controller also has hysteretic remapping of the switches based on end effector orientations, e.g., the angular spread relationship of the fingers. The “C” or hook-shaped switch triggers do not confine the operator&#39;s fingers, and thus enable the operator to grasp (don) and release (doff) the controller easily. 
     This controller provides an intuitive interface that enables even new operators to control an end effector (e.g., a robotic hand) effectively. In order to make the controller intuitive, the switches are operated by the natural flexion and extension of the operator&#39;s distal finger segments (tips). The operator&#39;s fingers slip into the curved triggers of the switching mechanisms. Movement of the operator&#39;s fingertip pivots the enclosing trigger and a lever arm portion of the trigger inside the shell of a controller housing. This pivoting of the lever arm presses it, alternately, on one of two snap action switches mounted above and below the lever arm. It is not possible to actuate both switches at the same time. Flexion of the operator&#39;s finger causes one switch to depress and actuate while extension causes the other switch to depress and actuate. 
     The operator selects among commonly used configurations (e.g., finger spread angles) of the end effector through a mode-selecting toggle switch on the controller. A fine-tuning knob on the controller adjusts the spread angles of the end effector fingers between the commonly-used, preset modes. Based on the configuration of the end effector, the controller automatically changes the mapping of each switching mechanism to the appropriate end effector peripherals (e.g., fingers where the end effector is a robotic hand). The finger mapping change facilitates intuitive control of the end effector peripherals. Depending on the orientation of the end effector peripherals, it is more natural for the operator&#39;s fingers to control different permutations of end effector functions. A hysteretic transition between the switching mechanism mappings controls operator confusion as the operator adjusts between the commonly used modes of the end effector. 
     The present invention makes improvements to switch selection, ease of use, and controller functionality. The present invention also uses a dual-action switching mechanism to eliminate the need for opposing switch pairs on the controller exterior. The operator actuates the above-described switches by opening and closing his or her hand, a motion that is intuitive for grasping and releasing objects. The dual-action switching mechanisms in the present invention have open endings. The finger of the operator passes through the hook-shaped trigger, allowing for operators with small and large hands to use the same pistol-grip controller. 
     The present invention also uses a plurality of switches, allowing for the control of higher-functionality end effectors, e.g., ones with multiple modes of operation. The multiple dual-action switches of the present invention are also manipulated by multiple fingers of the operator. These switches on a pistol-grip controller are more intuitive for grasping and releasing. This also allows the operator to control several functions on the end effector simultaneously. 
     The controller of the present invention is not mechanically linked to the end effector. As a result, it can be used to control several different real and virtual end effectors. 
     In one preferred form of the invention, there is provided an end effector controller that is gripped by an operator in one hand, comprising: 
     a pistol-grip housing configured to fit in the palm of an operator&#39;s hand when gripped and having mounted thereon a plurality of switching mechanisms with pivoting, dual-acting switch triggers each configured for independent actuation by multiple fingers of the hand when said controller is gripped. 
     In another preferred form of the invention, there is provided a method for controlling a robotic end effector remotely using an operator hand-gripped controller, the method comprising: 
     switching between preset operating modes of the end effector using a single, control input element, easily actuated by a finger in the operator&#39;s gripping hand; and 
     providing continuous fine adjustment between preset modes using a second, control input element also easily actuated by a finger on the operator&#39;s gripping hand. 
     In another preferred form of the invention, there is provided a controller that is gripped by an operator in one hand, comprising: 
     a pistol-grip housing configured to fit in the palm of an operator&#39;s hand when gripped and having mounted thereon a plurality of switching mechanisms with pivoting, dual-acting switch triggers each configured for independent actuation by multiple fingers of the hand when said controller is gripped. 
     In another preferred form of the invention, there is provided a method for controlling a device remotely using an operator hand-gripped controller, the method comprising: 
     switching between preset operating modes of the device using a single, control input element, easily actuated by a finger in the operator&#39;s gripping hand; and 
     providing continuous fine adjustment between preset modes using a second, control input element also easily actuated by a finger on the operator&#39;s gripping hand. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
         FIG. 1  is a front perspective view of a pistol-grip end effector controller formed in accordance with the present invention; 
         FIG. 2  is a rear perspective view of the same pistol-grip end effector controller; 
         FIG. 3  is a perspective view of the inside of the front portion of the pistol-grip end effector controller; 
         FIG. 4  is a perspective view of the inside of the rear portion of the pistol-grip end effector controller; 
         FIG. 5A  is a cross-sectional view of a switch trigger and its associated housing; 
         FIGS. 5B and 5C  are views corresponding to  FIG. 5A , but showing the switch trigger in two extreme positions to actuate two different internally-mounted electrical snap-action switches; 
         FIG. 6  is a perspective view of the switch trigger shown in  FIGS. 5A-C ; 
         FIGS. 7A-7D  show four preset modes or orientations of a robotic hand end effector controlled using the controller shown in  FIGS. 1-6 ; 
         FIG. 8A  is a robotic hand end effector as shown in  FIGS. 7A-7D  with two arms pivoted through a spread angle θ degrees from a third fixed arm; 
         FIG. 8B  is a diagram illustrating a proposed hysteresis of the finger remapping the robotic hand end effector; 
         FIGS. 9A-9C  are views in side elevation of three dual-action switch triggers shown in  FIGS. 1-6 ; and 
         FIG. 10  is a view in side elevation of a robotic hand end effector showing a finger in a typical position and in phantom, more closed and more open positions. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In accordance with the present invention, there is provided a controller  5  ( FIGS. 1 and 2 ) which can be used with a robotic end effector  10  ( FIGS. 7A-7D ) such as a multi-fingered robotic hand of the type sold by Barrett Technology, Inc. of Cambridge, Mass. under the trade designations “Barrett Hand” and “BH8”, and/or described, in one form, in U.S. Pat. No. 7,168,748 and sold by Barrett Technology, Inc. under the trade designation “Wraptor.” The controller  5  controls the movement of the robotic end effector  10 , including the fingers  15  ( FIGS. 7A-7D ) of the end effector in response to movement of the operator&#39;s fingers (“fingers” as used herein includes the thumb). The controller  5  has a “front” housing portion  20  ( FIG. 1 ) and a “back” housing portion  25  ( FIG. 2 ). These two housing portions are hollow, forming a shell-like housing  30  ( FIG. 2 ) to house electronics and manually-operated switches  35 ,  40 ,  45  and  50  ( FIG. 1 ) that each project from the outer surface of the housing  30 . The housing portions  20  and  25  are preferably formed of ABS plastic, each manufactured as a single piece by a stereolithography process. Other materials and manufacturing processes can be used. 
     The controller  5  reversibly attaches to a support (not shown) at its top end  55  ( FIG. 1 ) and bottom end  60  ( FIG. 1 ). Two fasteners  65  ( FIG. 1 ) at the top, and two fasteners  70  ( FIG. 1 ) at the bottom, provide a clamping force to anchor the controller to the support. The support is preferably a robotic multi-link arm such as the one sold by Barrett Technology, Inc. under the trade designation “WAM” and includes Barrett Technology&#39;s “Gimbals” option. Further, the controller  5  is mounted at the remote or distal end of the arm through the gimbal to back drive it as a “master” arm that is operatively coupled to a like “slave” robotic arm, with the end effector EE mounted at its distal end. 
     Fasteners  75  ( FIG. 1) and 80  ( FIG. 1 ) further secure the controller to the support. The housing portions  20  and  25  are aligned with each other by a lip  85  ( FIG. 3 ) and groove  90  ( FIG. 4 ) along the perimeter of portions  20  and  25 , respectively. The continuous, close alignment of the mated lip and groove ensures a smooth, continuous surface for the operator to grip. Fasteners  95  ( FIG. 3 ) secure the portions  20  and  25  to one another. 
     The housing  30  has an outer ergonomic, generally pistol-grip shape that conforms to the natural shape of an operator&#39;s hand H (in phantom in  FIG. 1 ). A bulbous protrusion  100  ( FIG. 2 ) extends from smaller attachment points at the top end  55  and bottom end  60  of the controller in order to fit into the palm of the operator&#39;s hand. A smooth ridge  105  ( FIG. 1 ) extends from the left side of the controller to support the operator&#39;s thumb in its natural orientation. A flat area  110  ( FIG. 2 ) on the right side of the controller provides a resting surface for the operator&#39;s other fingers. 
     The switch triggers  35 ,  40 ,  45  and  50  mounted on the controller  5  are located to be easily-accessible and intuitively actuated by the operator&#39;s fingers. More particularly, the “C” or hook-shaped switch triggers  40 ,  45 , and  50  are placed so as to be actuated by natural flexion and extension of the operator&#39;s fingers. A rocker switch  35  is placed so as to be easily actuated by the operator&#39;s thumb. The operator uses this rocker switch  35  to select among commonly-used orientations of the end effector peripherals as shown in  FIGS. 7A-7D . A thumb wheel  115  ( FIG. 2 ) is located so as to be easily rotated by the tip of the operator&#39;s thumb. This thumb wheel  115  is a fine-tuning knob to adjust the orientation (spread angle θ as shown in  FIG. 8A  of the end effector&#39;s fingers  15  between the commonly used modes. The thumb wheel  115  is operatively connected to two potentiometers  120 ,  125  mounted inside the housing, as shown in  FIG. 4 . A suitable potentiometer is sold by Panasonic as a single turn, continuous, surface mount unit. 
     The controller  5  of the present invention facilitates manipulation of the end effector  10  through rotations (roll, pitch, yaw) and displacements (x, y, z), produced by corresponding movement of the controller as a whole by the operator&#39;s hand, all without inadvertently actuating any of the switches. More specifically, the ergonomic outer shape of the controller affords gripping of the controller solely with the ball of the palm and the more proximal phalanges of the operator&#39;s fingers. This grip shape leaves the tips of the fingers to move freely and independently. They therefore do not apply pressure to the switch triggers  40 ,  45 , and  50  as the controller as a whole is manipulated. The ability to move the controller  5  as a whole, through a corresponding physical manipulation of the controller  5  as a whole, independently of the state of activation of any of the switches mounted on the controller  5 , is important in applications where the controller uses the orientation and location of the operator&#39;s hand to produce a like orientation and location of an end effector as a whole. An electrical connector  130  ( FIG. 1 ) allows connection of an external wiring harness to pass electrical signals from the internal electronics to external peripherals. Wires internal to the controller  5  that connect the switches and other electrical components are not shown but will be readily understood by one skilled in the art. A hook feature  135  ( FIG. 1 ) is used to secure and strain-relieve the external wiring harness. 
     The switch triggers  40 ,  45  and  50  are preferably open-ended “C” or hook-shaped as contemplated in a presently preferred form, one embodiment of which is illustrated in  FIGS. 1-3 ,  5 A- 5 C,  6  and  9 A- 9 C. This configuration provides control of the peripheral (e.g., a robotic finger  15 ) of an end effector  10  such as a robotic hand. The switch  40 , for example, has two opposed, curved faces  140 ,  145  ( FIG. 5A ) partially encircling a central recess  150  that receives the operator&#39;s pointer finger. The upper face  140 , above the finger as shown, provides a surface for the operator&#39;s finger to press against to open (release) the fingers  155 ,  160  ( FIG. 8A ) and fixed finger  165  ( FIG. 8A ). The lower face  145 , below the finger as shown, provides a surface for the operator&#39;s finger to press against to close (grip) the angular positions of the pivotable fingers  155 ,  160  and fixed finger  165 . The partial encirclement of the operator&#39;s fingers allows for free movement of the fingers in donning and doffing the controller. The width of the recess  150  tapers (narrows through the closed end of the “C”-shaped recess) so that fingers of varying size can easily reach both the top and bottom faces. 
     A hole  170  ( FIG. 6 ) through the center of the switching mechanism  40  accommodates a shaft  175  ( FIG. 5A ) about which the switch pivots. Holes  180  ( FIG. 1 ) in housings  20  and  25  support shaft  175 . A lever arm  185  ( FIG. 5A ) projecting inwardly from the external “C” or hook-shaped switch trigger portion acts alternately upon snap action, lever electrical switches  190  and  195  ( FIG. 5A ), e.g., of the type sold by Cherry. The hook-shaped switch is dual-acting in that a movement  200  ( FIG. 5B ) upwards of the finger of the operator against the face  140  actuates the snap action switch  195 , and a movement  205  ( FIG. 5C ) downwards of the finger of the operator against the face  145  actuates the snap action switch  190 . For example, when paired with a robotic hand end effector  10  shown in  FIGS. 7A-7D ,  8 A and  10 , the actuation of switch  195  sends a signal to command the robot finger  165  to open or release as shown in phantom finger  210  with motion  215  in  FIG. 10 , while actuation of switch  190  sends a signal to commands the robotic finger  165  to close as shown in phantom finger  220  with motion  225  in  FIG. 10  (for one representative robotic finger  15 ). 
     When the switch trigger is actuated, to close, the associated robotic finger  15  will move in the closing direction, and continue to move until the robotic finger closes on an object, or reaches a preset “fully closed” position beyond that shown in  FIG. 10 , or the operator releases pressure on the face  145  of the trigger  40  to a degree that the snap action switch  190  is no longer activated. To open the finger  15 , analogous motions and activations and deactivations occur, except that when opening the finger  15  is much less likely to encounter an object, but it can accidentally run into an obstruction. In short, the end effector robotic finger  15  only moves when one of the internal snap action, lever-arm-activated switches is activated. 
     The pivot shaft  175  and lever arm  185  allows the snap action switches  190  and  195  to be mounted inside the hollow shell  30 . The lower face  145  is recessed in a shallow cavity  230  ( FIG. 2 ) of the housing portion  20 . Consequently, the lower face  145  follows the shallow curve of the housing in that area, preserving the ergonomic, hand-conforming shape of the controller. 
     The hook-shaped switches  45  and  50  are similar to switch  40  in functionality. The hooked-shaped trigger switches  40 ,  45  and  50  are not limited to the foregoing description. Some variations are illustrated in  FIGS. 9A-9C . 
     A plurality of “C” or hook-shaped switch triggers may be mounted to the controller to facilitate independent control of several end effector peripherals. In the illustrated embodiment, three switches are shown, namely, a switch  40  for the index finger, a switch  45  for the middle finger, and a switch  50  for the thumb. Other embodiments, including two switches, four switches, or five switches, are also possible. 
     Because it is more comfortable for the operator if a finger extension motion encounters less resistance than the flexion motion, the pressure required to activate the switch mechanisms is adjustable. The snap action switches  190  and  195  may be interchanged with similar sized switches of increased or decreased mechanical resistance. Spring elements may also be added to the snap action switches to increase mechanical resistance. Regardless of the particular mechanical implementation, these arrangements make the amount of force required to actuate the switch mechanism in each direction different so as to more nearly equalize operator ease of opening and closing. Mechanically this arrangement creates a dual-action switching mechanism with a different actuation force for each direction of actuation. 
     The end effector  10  being controlled can have several different preset modes of operation. For example, with reference to  FIGS. 7A-7D ,  8 A and  8 B, the illustrated robotic hand may have preset configurations or spread angle modes  235  ( FIG. 7A ),  240  ( FIG. 7B ),  245  ( FIG. 7C ), and  250  ( FIG. 7D ). Each preset mode has different angular spread relationships between a fixed finger  165  and two pivotally movable fingers  155  and  160  that each pivot in a horizontal plane through a range of spread angles θ of 0° to 180° with respect to the finger  165 . It is beneficial to have these commonly used configurations easily accessible because they each have advantages for grasping different shaped objects such as small, round, or handled objects. Using thumb switch  35 , the operator toggles between the preset modes of the end effector. Depressing switch  35  in one direction will increase the spread of the fingers (e.g., from mode  235  to mode  240 ). Depressing it in the other direction will reduce the spread (e.g., from mode  240  to mode  235 ). The operator can turn knob  115  to make small adjustments around the preset modes. This also allows the operator to reach intermediate positions between the preset modes. 
     The controller  5  maps the switching mechanisms to different end effector peripherals based on the spread angle  255  ( FIG. 8A ) so the robotic peripherals respond more naturally to the inputs of the operator. For example, when the end effector is in mode  235  ( FIG. 7A ), switches  40 ,  45 , and  50  control the opening and closing of fingers  165 ,  155 , and  160 , respectively. This is mapping scheme  1 . When the end effector is in mode  250  ( FIG. 7D ), the switches  40 ,  45 , and  50  control the opening and closing of fingers  155 ,  160 , and  165 , respectively. This is mapping scheme  2 . In this manner, the robotic peripherals (i.e., fingers  155 ,  165 ,  160 ) visually correlate to the operator&#39;s fingers. The controller  5  of this invention thus functions under either mapping scheme  1  or  2  to make it more intuitive for the operator to control the end effector fingers. A hysteresis zone  260  ( FIG. 8B ) in the spread angle  255  ( FIG. 8A ) determines the switching point between mappings. This hysteresis zone occurs between modes  240  ( FIG. 7B) and 245  ( FIG. 7C ). This hysteresis prevents the mapping from changing several times when the operator is finely adjusting around a given spread angle  255 . 
     The foregoing mode presets, mappings and hysteresis zone are preferably implemented in software on the computer in the “master” and “slave” WAM arms that support the controller  5  and end effector  10 . Additional preset modes can be added easily, or modified. 
     In the preceding sections of this document, the controller  5  is discussed in the context of controlling movement of a robotic end effector  10 . However, it should be appreciated that controller  5  can also be used to control other devices as well, and/or to input control commands to other devices and/or systems. By way of example but not limitation, controller  5  can be used as a game controller for a video game, or as a flight controller for a drone aircraft, or as a flight controller for a guided missile, etc. In essence, controller  5  can be used as a controller for substantially any application where the hand and finger movements of an operator need to be sensed and converted into corresponding signals which are then used as an control input for a device and/or system. 
     While the foregoing written description of the invention enables one of ordinary skill in the art to make and use what is considered presently to be the best mode thereof, those of ordinary skill in the art will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the present invention.