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Description  |
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BACKGROUND OF THE INVENTION
1. Origin of the Invention
The invention described herein was made in the performance of work under a
NASA contract, and is subject to the provisions of Public Law 96-517 (35
USC 202) in which the Contractor has elected to retain title.
2. Field of the Invention
This invention relates to hand-held controllers and, more particularly, to
a hand-held controller for robot end effectors, which controller provides
force and position feedback to the operator.
2. Background of the Invention
Joystick, pistol-grip and other type hand-held controllers are well known.
The controllers move an end effector in a direction that corresponds to
the pivoted direction that the controller is moved. To add "feel" for the
user, it is known to add resistance of various types to the controller.
A known feel-creating means for a joystick control is described in U.S.
Pat. No. 3,771,037 to Bailey Jr., wherein a resilient bias means 24 is
depicted in FIGS. 2, 3 and 6 and is described at column 4 lines 28 through
50. Other joystick or pistol-grip controllers are depicted in George et
al, U.S. Pat. No. 3,637,092, wherein force feedback is presented at handle
45, and in Fick, U.S. Pat. No. 3,618,786, wherein a piston and cylinder
assembly 25, 26 or 27, FIG. 1, provide "feel". In each of these patent
disclosures the feedback of applied force is reflected as a resistance to
movement at the hand-held controller.
Another type of controller encloses the operator's hand and provides
signals at the hand to supply a "feel" that an action has taken place.
Typical of this type is an Australian Patent No. 408,797 disclosing a
bladder 47 which is located within a glove 11 that is worn by the
operator. The bladder 47 is inflated to impart a feedback resistance force
to the finger of the operator. A similar type system is disclosed in two
Russian Pat. Nos. 234,762 and 234,763 wherein an openable case 3 has an
inner surface that loosely embraces an operator's hand. In each one of
these Russian patents, the case is movable to impart motion to an end
effector. A handle is located within the opening in each case. In the '763
patent, the handle houses vibrators which cause a sensation on the palm of
the operator's hand. In the two Russian patents, the operator's thumb and
index finger fit within rings which drive a gripping mechanism, and also
receive feedback signals at sensation-creating vibrators, or pushers,
located at the tips of each ring.
In summary, then, it is known to provide control by a hand-held device, and
to equip that device with some type of feedback resistance as an
indication of a force applied at a controlled object. In other instances a
vibration, such as the vibrators in the Russian patents, indicates that an
action has taken place.
For sophisticated control over a robot end effector, it is a feature of
this invention to provide a single tactile area with simultaneous feedback
of both force and movement.
SUMMARY OF THE INVENTION
Briefly the subject invention comprises a hand held controller of the
pistol grip type for controlling a robot end effector and providing force
and position feedback to a single tactile area of the operator's hand. In
the preferred embodiment the single tactile area is located at the forward
end of the operator's index finger. The operator's finger fits within a
finger receiving trigger guard. The guard has a forward part surrounding
and generally conforming to the operator's outer portion of his index
finger and a rearwardly-located trigger held within the guard, with the
trigger including an index finger contact piece which is adapted to fit
against and generally conforms to the underside of the operator's index
finger. The operator controls both the position or movement and grasp
force of an end effector. Exerting pressure against the trigger inwardly
toward the palm of the operator's hand, controls the closing motion and
clamping force of the end effector. Pushing outwardly against the guard
and away from the palm reverses the command operations. During feedback
the operator can "feel" two distinct feedbacks at the end of his finger.
The trigger element adapted for contact with an operator's finger,
according to this invention, is both pivotable and rotatable in response
to feedback signals from the controlled end effector. Rotation of the
trigger element about its longitudinal axis is responsive to and reflects
the amount of grasp force that has been exerted by the end effector.
Deflection of the guard encasing that trigger around a pivot point is felt
by the controlling finger as an in-and-out motion that is responsive to
and reflects the amount of movement the end effector has achieved.
In this invention, responsive to feedback signals, the trigger and its
guard both pivot as a single unit inwardly (toward the palm) or outwardly
(away from the palm) in order to reflect position, whereas the trigger
within the guard is free to rotate relative to the rest of the
trigger-guard unit. The trigger contact piece has a concave cylindrical
section to better fit the operator's finger. The flat curved portion has a
definite width, which width, when it is rotated causes a distinct "feel"
to the underside of the operator's index finger. Rotation of the trigger
supplies a distinct and varying pressure by the trigger's cylindrical
surface bearing on the inside of the operator's finger. The amount and
direction of the rotationally induced pressure is felt as a sensation on
the operator's index finger, and is indicative of the grasping force
exerted by the controlled end effector.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional side elevation of the dual force controller of
this invention; and
FIG. 2 is an exploded perspective view of the interior parts within the
handle of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a side elevation of controller 20 which may advantageously
take the general shape of a pistol grip or joystick control for an
operator's hand. Controller 20 includes an appropriately shaped handle 22
having, in the foremost position thereof, a trigger guard, or housing, 23
and trigger 24. Trigger housing 23 is pivoted at point 25 so that force by
an operator's finger on trigger 24 or the inner area 23A of guard 23 tends
to move the housing 23 as shown by the double-headed arrow 26.
Pivotable force that tends to promote pressure applied at guard 23 about
pivot point 25, induces strain in a pair of strain guages 28, 29 located
on opposed surfaces of linkage 32. That strain, in a well-known manner, is
reflected in signals of opposite polarity depending upon the direction of
applied force by the operator's fingers. For example, if the operator's
finger pressure is such that the guard 23 tends to be moved inwardly
toward the palm, then guage 28 is in tension whereas guage 29 is in
compression and a motor command signal of one polarity results.
Conversely, a force tending toward movement of guard 23 away from the palm
results in the opposite conditions at guages 28, 29 and a signal of
opposite polarity is developed.
To control the end effector motion--such as the movement of a claw--the
operator exerts force on the trigger 24 with his finger or the operator
pushes outwards against the trigger guard surface 23A for a reverse
motion. Strain guages 28, 29 measure this force and translate it into
electrical signals which regulate an end effector motor. Thus, the
controlled position of a claw is proportional to the trigger force applied
by the operator. Once the controlled claw has moved into contact with an
object to be controlled, the claw movement stops but continued finger
force still produces command signals and the end effector continues to
receive motor control current. Continuation of that current then controls
grasp force by the claw. Various control systems responsive to this
operator-induced force are well-known and need no further description.
Suffice it to say that force tending to result in pivoting of guard 23 in
the directions of arrow 26 controls claw position and grasping force.
A position, or movement, feedback servomotor 35 of any well-known type is
located at the base of the handgrip 22. Motor 35 receives position
feedback signals from a controlled end effector in a well-known manner.
Motor 35 operates through a spindle 36 and linkage mechanism 37 to rotate
the guard 23/trigger 24 back and forth in the direction of arrow 26. As
shown in exploded view in FIG. 2, motor 35 drives a threaded post 35A upon
which is mounted a traveling nut 36A. Nut 36A moves up and down on post
35A depending upon the direction of rotation of motor 35. As nut 36A
travels, it pivots linkage 36 about the pivot point 38. A link 37 moves up
and down within handle 22 and that movement of link 37 pivots trigger
housing 23, via linkage 32, in the directions of arrow 26.
The trigger 24, relative to guard 23, does not yield responsive to the
operator's squeezing force. Instead it will receive feedback and will be
rotated by such feedback as is caused by and is responsive to claw
pressure. Located at the top of handle 22 is another servomotor 45 which
motor responds to signals generated on the claw by transducers or
equivalents in any well known manner. Motor 45 receives signals which are
proportional to the amount of grasping force being applied at the claw of
the end effector. Motor 45 drives a translational linkage member 46
through a directional change gear 47. Gear 47 is fixed upon a threaded
post 45A which houses a traveling nut 46A. As nut 46A moves, link 46
pivots a shaft 49. Shaft 49 is fixably attached to trigger 24. Trigger 24
rotates as shaft 49 rotates in response to the drive signals applied to
servomotor 45.
FIG. 4 is an exploded view taken of FIG. 1. A flat curved surface is
clearly shown at the finger touch area of trigger 24. The operator's
finger can readily feel the change in rotation of the flat surface of
trigger 24. For example, in response to one polarity of feedback signal,
trigger 24 rotates clockwise, whereas trigger 24 rotates counter clockwise
in response to a feedback signal, of opposite polarity. The magnitudes of
the feedback signal controls the amount of clockwise or counterclockwise
rotation that occurs. These feedback signals directly indicate the
grasping force at the end effector and that force is positively felt at
the operator's trigger finger.
This controller provides simple control actuation for claw control and
provides easily understood feedback functions, all presented at the
operator's finger. Other fingers of the operator's hand are free to
execute other control functions. For instance, the thumb may manipulate
strategically located buttons such as button 50, FIG. 1, at the back of
the handle 22. Moreover, the manipulations through the operator's finger
do not require eye contact, so that the operator can devote attention to
monitoring other functions. The controller thus lends itself well for
integration into a robot arm master controller.
The above description present the best mode contemplated in carrying out my
invention. My invention is, however, susceptible to modifications and
alternate constructions from the embodiments shown in the drawings and
described above. Consequently, it is not the intention to limit the
invention to the particular embodiments disclosed. On the contrary, the
invention is intended and shall cover all modifications, sizes and
alternate constructions falling within the spirit and scope of the
invention, as expressed in the appended claims when read in light of the
description and drawings.
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