U.S. patent number 3,637,092 [Application Number 05/033,442] was granted by the patent office on 1972-01-25 for material-handling apparatus.
This patent grant is currently assigned to General Electric Company. Invention is credited to Raymond L. George, Edward G. Kruszona, John P. Laniewski, Norman H. Wood.
United States Patent |
3,637,092 |
George , et al. |
January 25, 1972 |
MATERIAL-HANDLING APPARATUS
Abstract
An articulated boom having a single joint intermediate the ends
thereof is pivoted at one end about a horizontal axis of a support
member. The support member is in turn connected to a mount member
and pivoted about a vertical axis thereof. The other end of the
boom has end effectors and end effector positioning elements
located thereon. A control member smaller in size but similar in
form to the articulated boom having a single joint intermediate the
ends thereof is also pivoted at one end about another horizontal
axis of another support member and a handle is provided at the
other end thereof. The other support member is connected to the one
support member and pivotal to a limited extent about another
vertical axis. Hydraulic actuators, control valves and control
linkages are interconnected with the boom and the control member so
that movement of the handle causes the boom to mimic the movement
of the control member and also so that forces encountered by the
end effector on the boom are reflected back, reduced in magnitude,
however, to the handle held by the operator.
Inventors: |
George; Raymond L.
(Schenectady, NY), Kruszona; Edward G. (Schenectady, NY),
Laniewski; John P. (Scotia, NY), Wood; Norman H.
(Schenectady, NY) |
Assignee: |
General Electric Company
(N/A)
|
Family
ID: |
21870416 |
Appl.
No.: |
05/033,442 |
Filed: |
April 30, 1970 |
Current U.S.
Class: |
414/5; 901/15;
901/21; 901/22; 901/40 |
Current CPC
Class: |
B25J
3/04 (20130101) |
Current International
Class: |
B25J
3/04 (20060101); B25J 3/00 (20060101); B25j
003/00 () |
Field of
Search: |
;214/1CM,1BD,1BV,147R
;212/35,59 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Forlenza; Gerald M.
Assistant Examiner: Abraham; George F.
Claims
What we claim as new and desired to secure by Letters Patent of the
United States is:
1. In combination,
a mount member,
a slave support member pivotal about a first vertical axis on said
mount member,
a slave member including an upper arm element and a lower arm
element, one end of said upper arm element pivotally connected to
said slave support member and pivotal about a first horizontal
axis, the other end of said upper arm element pivotally connected
to one end of said lower arm element and pivotal about a second
horizontal axis, the longitudinal axes of said slave arm elements
lying in a first vertical plane perpendicular to said first and
second horizontal axes,
a master support member pivotally connected to said support member
and pivotable about a second vertical axis,
a master control member including an upper arm element and a lower
arm element, one end of said upper arm element connected to said
master support member and pivotable about a third horizontal axis,
the other end of said upper arm element pivotally connected to said
lower arm element and pivotal about a fourth horizontal axis, the
longitudinal axes of said master arm elements lying in a second
vertical plane perpendicular to said third and fourth horizontal
axes,
first means for transferring angular displacement of said lower
master arm element with respect to said upper master arm element
about said fourth horizontal axis to a corresponding angular
displacement of a first reference arm element about said first
horizontal axis,
second means for transferring angular displacement of said upper
master arm element with respect to said third horizontal axis to a
corresponding angular displacement of a second reference arm
element about said first horizontal axis,
first servo loop means responsive to the displacements of said
first reference arm element to maintain alignment of the
longitudinal axis of said lower slave arm element with the
longitudinal axis of said lower master arm element,
second servo loop means responsive to the displacements of said
second reference arm element to maintain alignment of the
longitudinal axis of said upper slave arm element with the
longitudinal axis of said upper master arm element,
said first transferring means includes means for transferring an
angular displacement of said lower master arm element with respect
to said upper master arm element about said fourth horizontal axis
to angular displacement about said third horizontal axis and means
in turn for transferring angular displacement about said third
horizontal axis to a corresponding angular displacement of said
first reference arm about said first horizontal axis, the
longitudinal axis of said first reference arm oriented in the same
direction as the longitudinal axis of said lower master arm
element,
means responsive to the orientation of the longitudinal axis of
said first reference arm and to the orientation of the longitudinal
axis of said lower slave arm element to produce a displacement in a
differential lever arm, the direction of displacement from a
neutral position and the magnitude thereof corresponding to the
direction and magnitude of misalignment of said lower slave arm
element and said lower master arm element.
2. The combination of claim 1 in which said means for transferring
an angular displacement of said lower master arm element with
respect to said upper master arm element about said fourth
horizontal axis to angular displacement about said third horizontal
axis includes a sprocket having the rotational axis thereof
coincident with said third horizontal axis and a first lever arm
pivotally connected to an intermediate point on said lower master
arm element and pivotally connected to a point other than the
center of said sprocket and said means for transferring angular
displacement about said third horizontal axis to a corresponding
angular displacement of said first reference arm about said first
horizontal axis includes another sprocket having the rotational
axis therein coincident with said first horizontal axis and an
endless chain with a small amount of slack intercoupling the
peripheral portions of said sprockets.
3. The combination of claim 2 in which said second transferring
means includes a second lever arm connected by a ball joint with a
small amount of tolerance therein to an intermediate point on said
upper master arm element and connected by another ball joint with a
small amount of tolerance therein to a tab means pivotal about said
first horizontal axis.
4. The combination of claim 2 in which said second vertical axis of
said master support member is horizontally displaced along said
first horizontal axis from said first vertical axis of said slave
support member and a slave support extension element member is
provided, said slave support extension member having one end
connected to said slave support member and the other end pivotally
connected to said master support member,
a pair of transverse members extending along said first horizontal
axis and having axes coincident therewith and rotatable thereabout,
one of said transverse members connected at one end to said second
sprocket and at the other end to said first reference arm and the
other of said transfer members connected at one end thereof to said
tab and at the other end to said second reference arm.
5. The combination of claim 4 in which an eccentric cam member is
provided fixed to said slave support extension having its axis
coincident with said second vertical axis and in which a button is
provided on a valve secured to said master support member which
bears on the peripheral surface of the cam.
6. The combination of claim 4 in which an operator support platform
is provided displaced along said horizontal axis beyond the
displacement of said master support member for supporting an
operator thereon, said platform being constituted to position an
operator facing away from said plane including said first
horizontal axis and said second vertical axis and at a height at
which an adjacent arm of said operator is adjacent said master
control member.
Description
The present invention relates in general to material handling
apparatus of the kind in which the movements of a control or master
member produces corresponding movements amplified in respect to the
force exerted thereby of a controlled or slave member, and in
particular relates to boom-type manipulator apparatus in which the
slave and master members include longitudinal elements which are
similarly connected, and also in which a portion of the force
exerted by the slave member is reflected back to the master member
to provide a sense of feel for the force being applied by the slave
member.
Such manipulators are useful in transporting material from one
point to another in the performance of useful work functions. One
such manipulator is disclosed in U.S. Pat. No. 3,333,716 Ziegler
issued Aug. 1, 1967 and assigned to the assignee of the present
invention. Manipulators of the kind described in the
above-referenced patent multiplies a man's strength and reach while
permitting most of the man's dexterity, mental capabilities and
versatility to be exercised in the operation thereof. Such a
manipulator includes a boom at one end supported and adapted to
move about a vertical and a horizontal axis in response to
corresponding movements of a control handle. Linear actuators,
mechanical linkages and control valves are provided in the
manipulator so that the movement of the handle causes a
corresponding movement in the boom and so that forces exerted by
the boom are reflected back to the control handle. By keeping man
in the manipulator system his ability to make on the job decisions
is retained. In addition, the manipulator responds to the natural
movement of a man's arm and retains his dexterity. The present
invention is directed to provide improvements in manipulators of
the kind described above.
An object of the present invention is to provide a manipulator of
relatively simple construction and high-performance capability.
Another object of the present invention is to provide a manipulator
in which an end effector on a slave member of the manipulator is
caused to move in spatial correspondence in three directions with
the movement of a handle attached to the end of a master or control
member and additionally in which force feedback from the slave
member to the master member is provided to the control handle in
each of the aforementioned three directions.
Another object of the present invention is to provide a manipulator
of the character described in which a single control element is
provided for all powered motions.
Another object of the present invention is to provide a manipulator
having a controlled arm member and a control arm member which are
similar and in turn are similar to the upper and lower arm elements
of an operator.
It is a further object of the present invention to provide a
manipulator which is organized so that the sensing and responding
interface elements of an operator are mated with corresponding
elements of a manipulator to the end that the mental and physical
capability of an operator can be used to the fullest in fast,
efficient, effective control of the slave member of the manipulator
to duplicate the motions of the arm of the operator.
In carrying out the invention in an illustrative embodiment thereof
there is provided an articulated boom having a single joint
intermediate the end thereof is pivoted at one end about a
horizontal axis of a support member. The support member is in turn
connected to a mount member and pivoted about a vertical axis
thereof. The other end of the boom has end effectors and end
effector positioning elements located thereon. A control member
smaller in size but similar in form to the articulated boom having
a single joint intermediate the ends thereof is also pivoted at one
end about another horizontal axis of another support member and a
handle is provided at the other end thereof. The other support
member is connected to the one support member and pivotal to a
limited extend about another vertical axis. Hydraulic actuators,
control valves, and control linkages are interconnected with boom
and the control member so that movement of the handle causes the
boom to mimic the movement of the control member and also so that
forces encountered by the end effector on the boom are reflected
back, reduced in magnitude, however to the handle held by the
operator.
The novel features which are believed to be characteristic of the
present invention are set forth in the appended claims. The
invention itself, however, together with further objects and
advantages thereof may best be understood by reference to the
following description taken in connection with the accompanying
drawings wherein:
FIG. 1 is a perspective view of an illustrative embodiment of the
invention.
FIG. 2 is an enlarged perspective view of a portion of the
apparatus of FIG. 1 showing the slave or controlled member and
master or control member and the interconnections thereof. For
reasons of clarity certain of the elements have been altered in
size without, however, affecting the basic structure and principle
of operation of the invention.
FIG. 3 is a schematic diagram of the hydraulic and electrical
systems of the manipulator of FIGS. 1 and 2.
Referring now to FIG. 1, there is shown a manipulator 10 having an
articulated boom or slave member 11 including an upper arm element
12 and a lower arm element 13. A control or master member 15
including an upper arm element 16 and a lower arm element 17 is
also provided. One end of the upper arm element 12 of the slave
member is pivotally connected to a stanchion or slave support
member 20 about a horizontal axis 21 to form a shoulder joint. The
slave support member 20 is supported in the bearing member 22 which
is connected to a base or mount member 23. The support member 20 is
pivotal on mount member 23 about a vertical axis 24 thereof. The
other end of the upper arm element 12 is pivotally connected to one
end of the lower arm element 13 to form an elbow joint and is
pivotal about a second horizontal axis 14. The other end of the
lower arm element 13 has connected thereto end effector positioning
apparatus 25 and an end effector 26. The end effector positioning
apparatus 25 comprises three rotary elements 27, 28 and 29,
connected in series so as to permit movement of the end effector 26
about any one of three mutually perpendicular axes. The end
effector 26 shown is one in which suction cups 31-34 are provided
for interfacing and securing thereto objects to be moved by the
manipulator.
The upper arm element 16 of the master control member is pivotally
connected to a master support member 40 and is pivotal about a
third horizontal axis 41. The master support member 40 in turn is
pivotally mounted to the slave support member 20 and is displaced
horizontally therefrom so as to be pivotal with respect thereto
about a second vertical axis 42. The other end of the upper arm
element 16 is pivotally connected to one end of the lower arm
element 17 and pivotal about a fourth horizontal axis 43. A handle
45 is provided on the other end of the lower master arm element 17.
The handle 45 is provided with buttons, switches and the like
responsive to finger action to effect through appropriate
electrical and hydraulic control elements the operation of the end
effector positioning elements 27-29 and the end effector 26. Also
connected to the slave support member 20 and displaced horizontally
from the slave support member so that the control member 15 is
positioned between an operator of the manipulator apparatus and the
slave member is a platform or operator support member 50 shown in
the form of a seat for the operator and a foot rest so that the
operator is oriented in the direction in which the end of the slave
member 11 is oriented and the operator moves in azimuth so as to
maintain such orientation. The control arm member 15 is provided
with elements 16 and 17 which are comparable in length with the
corresponding portions of the adjacent arm of an operator so that
motions of the arm of the operator when grasping the handle
produces motions in the elements of the control member 15 which
correspond to the motions of the arm of the operator. Also, the
ratio of the length of the lower arm element of the master member
to the length of the lower arm element of the slave member is made
substantially equal to the ratio of the length of the upper arm
element of the master member to the length of the lower arm element
of the slave member to provide a good sense of position
correspondence between handle 45 and end effector 26. Hydraulic
actuators, control valves, and control linkages are interconnected
with the slave member 11 and the control member 15 in a manner
which will be fully described in connection with FIGS. 2 and 3 so
that as an operator moves the handle 45 of the control member 15,
the elements of the slave member 11 mimic the motion of the
elements of the control member 15. Accordingly, the position of the
hand of the operator produces a corresponding position of the end
effector 26 and, in addition, force exerted by the end effector on
an object is reflected back to the handle 45 reduced in magnitude
so that the operator has a feel for the force being applied by the
slave member.
Reference is now made to FIG. 2 in which elements corresponding to
the elements of FIG. 1 are denoted by the same reference symbol.
The slave support member 20 is a stanchion generally U-shaped to
the base of which is connected to a vertically extending shaft 51
which extends vertically downward and is supported in the
manipulator mount member 23 by bearing 22 and a thrust bearing (not
shown) located below the member 20. To the lower end of the shaft
51 is connected a sprocket 52 the teeth of which are engaged by a
chain 53. One end of the chain 53 is connected to the piston of a
hydraulic actuator 54 and the other end thereof is connected to the
piston of another hydraulic actuator 55. The cylinders of the
actuators 54 and 55 are secured to the support 23. Accordingly, by
appropriate energization of the actuators with hydraulic fluid the
slave support member 20 can be made to move about the first
vertical axis 24. Bearing surfaces are provided in the opposed
regions of the legs of the slave support member 20 and journals are
provided in one end of the upper slave arm element 12 for enabling
movement of the upper arm element about the horizontal axis 21. The
upper arm element may be a structural element rectangular in cross
section or of other columnar design to provide the desired strength
thereto. In this figure the element 12 is shown open for the
purposes of illustrating the embodiment of the invention. To the
other end of the upper arm element 12 is pivotally connected one
end of the bearing elements located in lower arm element 13 by
means of the elements 12 and 13. The lower arm element is pivoted
about the second horizontal axis 14 with respect to the upper arm
element. The upper arm element and the lower arm element have
longitudinal axes which intersect and lie in a vertical plane which
is perpendicular to the aforementioned first horizontal axis 21 and
the second horizontal axis 14.
The master control member 15 includes an upper arm element 16 and a
lower arm element 17. One end of the upper arm element 16 is
connected to master support member 40 and is pivotal with respect
thereto about a third horizontal axis 41. Master support member 40
is connected to a slave support extension member 56 so as to be
pivotal about the second vertical axis 42 to a limited extent. The
second vertical axis 42 is horizontally displaced along extension
member 56 from the first vertical axis 24. The first vertical axis
24, the first horizontal axis 21 and the second vertical axis 42
lie in a vertical plane. The other end of said upper arm element 16
is pivotally connected to one end of the lower arm element 17 of
bearing elements by means located in elements 16 and 17 and is
pivotal about a fourth horizontal axis 43. The other end of the
lower arm element 17 has secured thereto a handle 45 for
manipulation of the control member 15. The longitudinal axes of the
upper arm element 16 and the lower arm element 17, respectively,
intersect and lie in a second vertical plane perpendicular to the
aforementioned third horizontal axis 41 and fourth horizontal axis
43 and intersecting the aforementioned vertical plane including the
first and second vertical axes.
A first linkage means 60 is provided for transferring angular
displacement of the lower master arm element 17 with respect to the
upper master arm element 16 about the fourth horizontal axis 43 in
a corresponding angular displacement of a first reference arm
element 61 about the first horizontal axis 21 and includes a
sprocket 62 mounted to a shaft 63 which is pivotally supported in
the sidewalls of the master support member 40, and which pivotally
supports upper arm element 16, a lever arm 64 at one end pivotally
connected to an intermediate point on the lower arm element 17 and
at the other end pivotally connected to a side of the sprocket 62.
Accordingly, movement of the lower arm element 17 about the upper
arm element 16 causes a corresponding movement of the sprocket 62.
The angular displacement of the sprocket 62 about the third
horizontal axis 41 which is coincident with the axis of the shaft
63 is transferred to angular displacement about the first
horizontal axis 21 by means of another sprocket 65 fixedly mounted
to one end of tubular member 66 having its longitudinal axis
coincident with the first horizontal axis 21 and rotatable
thereabout. The tubular member 66 is rotatably supported in the
tubular slave support extension member 56. An endless chain 67 with
a small amount of slack engages the teeth of the sprockets 62 and
65 and interconnects them. The reference arm element 61 is
connected to the other end of the tubular member 66. Accordingly,
the movement of the sprocket 62 about the third horizontal axis is
transferred through the second sprocket 65 and through the tubular
member 66 is transferred to the tab 61 to produce a rotation of the
longitudinal axis thereof about the first horizontal axis 21.
Second linkage means 70 are provided for transferring angular
displacements of the upper master arm element 16 with respect to
the third horizontal axis 41 to a corresponding angular
displacement of a second reference arm element 71 about the first
horizontal axis 21 and includes a second lever arm 72 which at one
end is universally pivotal about a shaft 73 rigidly connected to a
point on the upper master arm element 16 and at the other end is
universally pivotal about a shaft 74 rigidly connected to an offset
75 member rigidly mounted on shaft 76. Shaft 76 has an axis of
rotation coincident with the first horizontal axis 21. The shaft 76
is rotatably supported within extension member 56 and connects to
reference arm 71 at the other end thereof. The socket 78 is
provided at one end of lever arm 72 which engages a ball 79 fixedly
secured to shaft to provide a universal joint. Similarly, a socket
80 is provided at the other end of lever arm 72 which engages a
ball 81 fixedly secured to shaft 73 to provide another universal
joint. Enough play is provided in the aforementioned universal
joints so that small angular displacements, for example less than
10 degrees, of the support member 40 about axis 42 with respect to
extension member 56 on which member 40 is pivotally mounted does
not bind the universal joints yet allows the indicated
displacements to take place. Accordingly, movement of the upper
master arm element 16 about the third horizontal axis 41 causes a
movement of the shaft 76 about the first horizontal axis 21 which
in turn causes the second reference arm 71 to execute a
corresponding movement about the first horizontal axis.
A system of levers is provided responsive to the orientation of the
longitudinal axis of the first reference arm 61 to the orientation
of the longitudinal axis of the lower slave arm element 13 to
produce a displacement in a differential lever arm 85. The
direction of such displacement of the lever arm 85 from a neutral
position and the magnitude of such displacement corresponds to the
direction and magnitude of misalignment of the lower slave arm
element 13 and the lower master arm element 17. To this end a lever
86 is provided connected between the remote end of the first
reference arm 61 and one end of the differential lever arm 85.
Another lever 87 is provided connected between an extension of the
lower slave arm beyond the horizontal pivotal axis 14 thereof and
the other end of the differential lever arm 85. An intermediate
point 88 on the differential lever arm 85 is connected to one end
of an actuating arm 89, the other end of which is pivotally secured
to the upper slave arm element 12. The longitudinal axis of the
first reference arm 61 is aligned to correspond with the
longitudinal axis of the lower master arm element 17. Accordingly,
a movement of the lower master arm element provides a corresponding
angular displacement of the reference arm which produces a movement
in one direction of the differential arm 85. If the other end of
the differential arm is maintained fixed the movement of the
differential arm is in the same direction. To maintain the
actuating arm 89 fixed in position, it is necessary to move the
other end of the differential arm 85. Accordingly, the magnitude
and direction of the movement of the actuating arm 89 corresponds
to the magnitude and direction of movement of the longitudinal axis
of the lower master arm 17. Such movement is sensed by a control
valve 90 connected to the upper slave arm element 12. The control
valve has a button which is moved in one direction or the other
from a neutral position to cause fluid to flow from one side to the
other or vice versa of a slave hydraulic linear actuator 91
connected between the upper slave arm element 12 and the lower
slave arm element 13. The control system is polarized so that the
flow of fluid causes the actuator 91 to bring the lower slave arm
13 into correspondence with the lower master control arm 17. Such
action causes the differential lever arm to be moved so as to
maintain the actuating arm 89 in a neutral position.
A second servo loop means is provided responsive to the
displacement of the second reference arm 71 to maintain alignment
of the longitudinal axis of the upper slave arm element 12 with the
longitudinal axis of the upper master arm element 16. Connected to
the upper slave arm element 12 is another control valve 92 having a
button 93 which bears against the second reference arm 71. Movement
of the reference arm 71 in one direction or the other corresponding
to movement of the upper control arm 16 in one direction or the
other about the third horizontal axis 41 causes a displacement of
the button 93 inward or outward, and accordingly directs hydraulic
fluid to flow in one direction between the ends of the linear
actuator 94 or in the other direction to cause the slave arm
element 12 to move in one direction or the other to maintain
correspondence in the direction of the longitudinal axis thereof
with respect to the longitudinal axis of the upper control arm
element 16.
A third servo loop means is provided responsive to the displacement
of the second vertical plane, that is the plane of the longitudinal
axes of the elements 16 and 17 of the control member 15 about the
second vertical axis 42 from a position in which it is parallel to
the first vertical plane, that is the plane including the
longitudinal axes of the elements 12 and 13 of the slave arm member
11, for maintaining the planes in parallel. To this end the slave
support extension member 56, one end of which is secured to the
stanchion 20 is provided at the other end thereof with a U-shaped
member 95, the base 96 of which is attached to the tubular member
56. A pair of bearing elements are provided, one in each of legs 97
and 98 of the U-shaped member 95 in opposed relationship and
aligned along the second vertical axis 42. The bearing element
associated with leg 97 includes a shaft 99 secured to the leg 97.
To the upper end of the shaft 99 is secured a cam 100 having a
peripheral surface 101 which is eccentric with respect to the
second vertical axis 42. A bracket 102 having an upper horizontal
portion 103, a lower horizontal portion 104 and a side portion 105
is connected between opposed walls of the support 40. The upper
horizontal portion 103 is connected to the wall of the support 40
adjacent the slave member 11, the side portion 105 is connected to
the opposed wall of the support 40 and the lower horizontal portion
104 is provided with a bearing which engages a journal in leg 98 of
the U-shaped member 95. As mentioned above, a bearing element is
provided in the upper horizontal portion 103 so as to permit
pivoting of the support 40 with respect to member 95 about the
second vertical axis 42. A servovalve 106 having an actuating
button 107 is mounted to a wall of the support 40. The button 107
bears against the peripheral surface 101 of the cam 100. When the
aforementioned second vertical plane is aligned with the
aforementioned first vertical plane, the button 107 of valve 106 is
in a neutral position on the cam 100. When the control arm member
15 is moved in one azimuth direction, the support 40 is displaced
about the vertical axis 42 in one direction and the cam displaces
the button in one direction to produce a flow of hydraulic fluid
through the actuators 54 and 55 to cause the shaft 51 to move in a
direction to align the first vertical plane with a second vertical
plane. Conversely, when the control arm member 15 is moved in the
opposite azimuth direction the cam 100 displaces the button 107 in
the opposite direction from neutral to cause actuators 54 and 55 to
move shaft 51 in the opposite direction to align the first and
second vertical planes. The movements of the control arm member 15
in one direction or the other about the second vertical axis 42
need not be large, i.e., less than a degree, since it need be
sufficient only to produce sufficient error signal in the servo
loop to cause the slave arm member 11 to move in correspondence
therewith. The provision of a chain 67 linking the first sprocket
62 and second sprocket 65 which is slightly slack enables such
limited movement to be performed without binding the mechanism.
Similarly, the lever arm 72 having ball and socket joints on the
ends thereof with a small tolerance is provided to avoid binding of
the lever arm yet permitting the error signal in the servo loop to
be produced.
Limit switches 110 and 111 are provided responsive respectively to
engagement of cams 112 and 113, therewith in the azimuth limit
positions of the support member 20 to block flow of fluid to the
actuators 54 and 55 and thereby limit the azimuth excursion of the
support member 20 to those limits. The circuit connections and
operation of the limit switches 110 and 111 will be further
described in connection with FIG. 3.
Force feedback is applied to the handle 45 by means of linear
actuators 114, 115 and 116. The linear actuator 114 pivotally is
connected between the elements 16 and 17 to provide torque about
the fourth horizontal axis 43. The linear actuator 115 is pivotally
connected between element 16 and master support member 40 to
provide torque of the third horizontal axis 41. The linear actuator
116 is pivotally connected between members 40 and 95 to provide a
torque about the second vertical axis 42. As mentioned above,
actuator 91 is connected between elements 12 and 13 and is used for
applying torque about the second horizontal axis 14. Actuator 94 is
connected between element 12 and member 20 and is used for applying
a torque about the first horizontal axis 21. The actuators 54 and
55 are connected to a chain 53 which moves the element 20 about the
first vertical axis 24.
Each of the slave actuators 91, 94 and 54, and 55, and also each of
master actuators 114, 115 and 116 is in an assembly of a cylinder
with a piston therein and has a pair of fluid ports, one at each
end of the cylinder. The application of a pressure differential
between one side and the other side of the piston produces a net
force thereon. The magnitude of such force and the direction of
such force being dependent upon the magnitude and direction of
pressure differential and, of course, on the active cross-sectional
area of the piston. The active area of each of the pistons of
actuators 114, 115 and 116 is substantially smaller by a
predetermined ratio than the active area of each of the pistons of
actuators 91, 94, 54 and 55. The pressure differential applied to
each of actuators 114, 115 and 116 is substantially the same as
appearing across respective actuators 91, 92 and one of the pair of
actuators 54 and 55. The actuators 114, 115 and 116 are
mechanically connected to provide torque lever arms about
horizontal axes 43, 41 and vertical axis 42, respectively which are
substantially smaller than lever arms provided to actuators 91,94
and one of a pair of actuators 54 and 55, respectively. Each of the
actuators 114, 115 and 116 are situated in respect to the
corresponding actuator or pair of actuators on the slave member in
a kinematically similar position so that the ratio of slave torque
to master torque for a pair of corresponding horizontal axes is the
same for any location of the handle 45. Preferably such ratio is
made the same for each of the three sets of axes so that force fed
back to the handle is a faithful replica of the force encountered
by the end effector 26. Also, of course, actuators 114, 115 and 116
are connected in circuit so that pressure differential existing
thereacross is opposite in direction to the pressure differential
existing at actuators 91, 94 and at pair of actuators 54 and 52,
respectively, to provide a restaining force to the movement of the
handle 45 which produced the force in the slave member.
The magnitude and direction of pressure applied to each of the
actuators 91, 94, and 54 and 55 is controlled by a hydromechanical
servo valves 90, 92 and 106. As mentioned above, servo valve 90
controls the pressure applied to actuator 91, valve 92 controls the
pressure applied to actuator 94 and valve 106 controls the pressure
applied to actuators 54 and 55.
The structure of each of the control valves 90, 92 and 106 and the
manner of their connection to respective slave actuators 91, 94 and
a pair of linear actuators 54, 55 as well as the operation thereof
will be explained in detail in connection with FIG. 3. Also in
connection with FIG. 3, the manner of applying pressure
differential appearing across each of the slave linear actuators
91, 92 and the azimuth set 54 and 55 to the force feedback linear
actuators 114, 115 and 116, respectively, will also be
described.
Reference is now made to FIG. 3 in which elements identical with
the elements of FIG. 2 are denoted by the same reference symbols.
Specifically, in this figure are shown mechanical servo valves 92,
90 and 106 for controlling fluid flow to respective linear
actuators 91, 94 and pairs of linear actuators 54 and 55. Each of
the servo valves 92, 90 and 106 is a four-way proportional control
pressure flow valve to which a mechanical input on a button thereof
produces a flow at a pair of output ports P.sub.1 and P.sub.2 the
magnitude and direction of which is proportional to the magnitude
and direction of movement of the button about a neutral position.
In addition to the output ports P.sub.1 and P.sub.2, each of the
valves is provided with a source port S for the application of
fluid pressure from a reservoir or a pressure generator and a
return port R therefor. Each of the control valves is a valve such
as a type 50-346 hydromechanical servo valve manufactured by Moog
Inc. of Proner Airport, East Aurora, N. Y.
As mentioned above, each of the linear actuators 91, 94 and 54 and
55 include a cylinder and a piston movable therein. The cylinder is
provided with a port at one end and another port at the other end
thereof. The application of a pressure differential between the
ports of the cylinder provides a force between the piston and
cylinder thereof. Coupling members are connected to the piston and
the cylinder which in turn are connected to appropriate elements
between which it is desired to apply the force. As shown in this
figure, the linear actuator 94 is connected between elements 12 and
20. Linear actuator 91 is connected between elements 12 and 13. The
piston of linear actuator 54 is connected to one end of chain 53,
the other end of which is connected to the piston of actuator
55.
The hydraulic fluid source line 118 of a source of pressurized
hydraulic fluid is connected to each of the source ports of the
valves 92, 90 and 106 and the return ports of each of the control
valves 92, 90 and 106 are connected to the return line 119 of
hydraulic fluid source. The output ports P.sub.1 and P.sub.2 of
control valve 92 are connected over lines 120 and 121,
respectively, to respective ports on the linear actuator 94. Line
120 includes fluid pathway of a two-way directional control valve
122 which is open when electrically energized and closed when
deenergized. The valve 122 provides a means to lock the actuator 94
in the event of electric power failure. The output ports of the
valve 90 each are connected to respective ports of the linear
actuator 91 along lines 124 and 125. Line 124 includes another
fluid pathway of valve 122 which is open when energized and closed
when deenergized. Valve 122 also provides a means to lock actuators
91 as well as 94 in the event of power failure. Each of the output
ports P.sub.1 and P.sub.2 of valve 106 is connected to a respective
port linear actuator the ports at the same end of the linear
actuators 54 and 55 over lines 126 and 127. The other ports of the
linear actuators 54 and 55 are connected together and are connected
to the return line 119 of the fluid source. A lock valve 128 is
connected in line 126 to block fluid flow therein when electrically
deenergized by limit switch 110 electrically connected thereto.
Similarly, lock valve 129 is connected in line 127 to block fluid
flow therein when electrically deenergized by limit switch 111
electrically connected thereto.
Force feedback to the elements 16 and 17 are provided by linear
actuators 115 and 114 which as mentioned are connected between
elements 16 and 40 and 16 and 17, respectively. While the pressure
difference appearing across the slave actuator 94 and the slave
actuator 91 could be applied respectively to the linear actuators
115 and 114, because of the large difference in masses of the
master and slave circuits instabilities are produced in such
circuits. Accordingly, in order to stabilize the master loop,
isolation is provided which makes the master control circuit
relatively independent of the slave circuit. The isolation is
achieved by actuator 94 and actuator 115, a pair of pressure
sensors 130 and 131, a differential amplifier 132 and a control
valve 133 and similarly for actuator 91 and actuator 114 providing
a pair of pressure sensors 135 and 136, a differential amplifier
137 and a control valve 138.
Each of the valves 133 and 138 are electrohydraulic flow valves
having a source port S and a return port P and a pair of output
ports P.sub.1 and P.sub.2. The valve is provided with solenoids
responsive to current applied thereto to control the flow in the
valve. Input current flow into one solenoid produces a flow in one
direction between the output ports P.sub.1 and P.sub.2, the
magnitude of which depends upon the magnitude of the current.
Similarly, input current flow to the other solenoid produces a
fluid flow in the opposite direction between the output ports
P.sub.1 and P.sub.2, the magnitude of which is dependent upon the
magnitude of such current flow. The electrohydraulic flow valve is
of a type such as type 30 Flow Control Servo Valve made by Moog
Inc., Proner Airport, East Aurora, N. Y. Each of the pressure
transducers 130, 131, 135 and 136 are transducers of the
strain-gauge-type and have a pair of fluid pressure input ports and
a pair of electrical output terminals from which a voltage is
derived proportional to the pressure differential applied between
the input ports. The magnitude and the direction of the voltage is
dependent upon the magnitude and direction of the pressure applied
between input ports of the strain gauge. The pressure transducers
or sensors such as Model 620-1 manufactured by Standard Controls
Inc., South Bayview St., Seattle, Wash., may be used. Each of the
differential amplifiers 132 and 137 has a pair of input channels
and a pair of output channels. The amplifier compares the signals
applied to the input channels and develops an output current in one
channel or the other depending on which of the two signals is
larger. The magnitude of the output current depends on the
magnitude of the difference. The pressure input ports of pressure
sensor 130 are connected to the ports of the actuators 94. The
pressure input ports of pressure sensor 131 are connected to ports
of actuator 115. The electrical outputs of sensors 130 and 131 are
applied to respective input channels of the amplifier 132. Each of
the output channels of the amplifier 132 are applied to a
respective solenoid of the control valve assembly 133. Each of the
output ports P.sub.1 and P.sub.2 of control valve assembly 133 are
applied to a respective port of actuator 115. Accordingly, when the
pressure differential between the ends of the actuator 94 and the
actuator 115 are the same, the outputs from the transducers 130 and
131 are the same and no net output would be produced from the
amplifier 132, consequently no fluid flow would appear at the
output ports P.sub.1 and P.sub.2 of the valve assembly 133. Should
the linear actuator 94 be energized by fluid flow or pressure
differential appear between the ends thereof, a signal would be
produced in transducer 130 which would produce a net output from
the amplifier 132 and would accordingly actuate valve assembly 133
to apply fluid pressure to the linear actuator 115 to develop an
output from the transducer 131 and accordingly restore balance to
the system. The elements of the feedback loop are phased in a
manner to produce such restoration.
Similarly, the pressure input ports of pressure sensor 135 are
connected to the ports of the actuator 91. The pressure input ports
of sensor 136 are connected to the ports of actuator 114. The
electrical outputs of sensors 135 and 136 are applied to respective
input channels of the amplifier 137. Each of the output channels of
the amplifier 137 are applied to a respective solenoid of the
control valve assembly 138. Each of the output ports P.sub.1 and
P.sub.2 of the control valve 138 is connected to a respective port
of actuator 114. The circuits described are so phased that the
pressure differential appear across the ends of the actuator 91 are
essentially matched by a pressure differential across actuator 114
in the manner described above in connection with actuators 94 and
115. The linear actuator 116 for azimuth force feedback has a
cylinder thereof connected to the element 40 and the piston
connected to the element 95. One port of actuator 116 is connected
to a port of actuator 54 and the other port thereof is connected to
a port of the actuator 55, each through respective orifices 140 and
141. The fluid circuit connections are made so that actuator
provides a force to member 40 counter to the movement thereof which
produced movement of member 95. The actuator 116 not only provides
force feedback but also acts in conjunction with the orifices 140
and 141 as a dashpot to stabilize the operation of the master
azimuth circuit. The stabilizing circuit is described and claimed
in a copending Pat. application, filed Apr. 30, 1970, Ser. No.
33,191 and assigned to the assignee of the present invention.
Reference is now made again to FIGS. 1 and 2 in which is shown a
plurality of rotary actuators 27, 28 and 29. Each of the actuators
has a stator and a rotor. Each of the actuators is fluid operated.
The rotor of actuator 27 is connected to the end of the member 13
and the stator of actuator 27 is connected to the rotor of actuator
28. The stator of actuator 28 is connected to the stator of
actuator 29, the rotor of which is connected to the end effector
26. A plurality of finger operated switches 145, 146 and 147 are
provided on the handle 45. Movement of the switch 145 to the left
or right causes electrical and hydraulic circuits to be actuated to
move the end effector 26 to be moved in yaw by actuator 28 to the
left or right. Moving the switch 145 forward or reverse causes
electrical and hydraulic circuits to be energized to actuate the
rotary actuator 27 to move the end effector 26 up and down in
pitch. Actuation of the trigger switch 146 causes electrical and
hydraulic circuits to energize the rotary actuator 29 to rotate the
end effector 26. Each of the rotary actuators 27, 28 and 29 are
rate actuators in that upon the application of fluid the rotor
thereof moves with respect to the stator until energization is
removed or until appropriate stops are reached for each of the
actuators which limit the movement of the rotors with respect to
the stator thereof. The base of the cups 31, 32, 33 and 34 are
provided with openings each of which are sealed by a cover. The
cover is mechanically opened upon the interfacing of the cups with
a surface of the object to be moved thereby by vacuum forces secure
the object to the end effector. The switch 147 provides a means for
releasing vacuum and hence breaking the seal between the end
effector and the object to be moved.
In operation of the manipulator apparatus of FIGS. 1, 2 and 3, the
operator would initially set on the seat of support member 50 and
grasp handle 45 on the master control member. Upon energization of
the hydraulic and electrical circuits of the system to free the
slave elements from a stowed position, the apparatus would be ready
for operation. Movement of the handle 45 in an arbitrary direction
in space would produce a corresponding movement of the end of the
element 13 and the end effector 26 into a corresponding position.
Such operation would be produced by the servoing action described
above. If such arbitrary movement of hand 45 required that element
17 be moved with respect to 16, tab 61 would be moved to produce a
corresponding movement in the arm 89 which would actuate the
control valve 90 in appropriate direction to energize linear
actuator 91 to bring the element 13 into correspondence with the
orientation of element 17. Similarly, if such arbitrary movement of
the handle 45 required that element 16 be moved about its
horizontal axis 41, the control valve 92 would produce a fluid flow
into linear actuator 94 to cause the spatial orientation of element
16 to line up with the element 12. Similarly, if such arbitrary
movement of handle 45 required that support member 40 be moved in
azimuth direction with respect to the horizontal axis 42, the servo
valve 106 would be actuated to actuate the linear actuators 54 and
55 in the appropriate direction to cause the slave support member
20 to move in azimuth in correspondence with the movement of the
control handle. If now the handle 45 is moved so as to cause the
end effector 26 to abut an object, force applied to the object is
reflected back to the handle 45 reduced in magnitude by a
predetermined ratio as described above by virtue of the fact that
force feedback cylinders 114, 115 and 116 are connected between
elements 17 and 16, between elements 16 and 40, and elements 40 and
95, respectively. Accordingly, the operator has a sense of feel for
the amount of force that his movement of the handle produced. If it
is desired now to lift an object such is accomplished by means of
the end effector 26. The handle now can be retracted to position
the object. In effect, movement of the handle gives the operator
the sensation of picking the object up by his hand and placing it
in the new location. The reach of the operator and the force that
he can apply however is now much greater. Having the control member
placed between the slave member and the operator makes it possible
for the operator effectively to use his senses, his sight as well
as his sense of feel, to respond to situations as he would were he
grasping an object.
While we have shown a particular embodiment, it will of course, be
understood that we do not wish to be limited thereto since many
modifications may be made in the arrangement shown and in the
instrumentalities employed. We contemplate by the appended claims
to cover any such modifications as fall within the true spirit and
scope of our invention.
* * * * *