End effector

The end effector forms part of the relocatable space station remote manipulator system. The end effector has grappling capabilities and latching capabilities and may include a force moment sensor which can cooperate with the arm in order to align the end effector with a grapple fixture without the aid of a grappling mechanism. The function of the end effector, when two are installed, one on each end of a symmetrical manipulator arm is to provide the capability to interchange the wrist and shoulder functions of the arm, thus enabling the manipulator to be self relocatable. The end effector combines the snare and rigidizing features of existing end effectors with new latching and umbilical electrical power and signal transfer features.

This invention relates to an end effector. 
PRIOR ART 
An end effector of the type which incorporates a grappling device is 
disclosed in U.S. Pat. No. 4,105,241 dated August 18, 1978. While this end 
effector is every effective in grappling a grapple fixture and serves to 
rigidize the end effector with respect to the grapple fixture, it is not 
designed to permit heavy loads to be transferred across the interface 
between the end effector and the grapple fixture. The cable system of the 
snare of the grapple device is not well suited to high load applications. 
A self-relocating manipulator assembly is disclosed in U.S. Pat. No. 
4,585,388 dated April 29, 1986. In this device, end effectors are located 
at opposite ends of an arm assembly. The manipulator assembly is capable 
of selectively employing either of the two end effectors to provide a 
shoulder connection while the other is used as a grappling device. Again, 
the end effectors are constructed substantially in accordance with U.S. 
Pat. No. 4,105,241. Consequently, the limitations of the end effector of 
U.S. Pat. No. 4,105,241 apply when the end effector is used to provide the 
shoulder joint. Generally, the loads applied at the shoulder joint will be 
greater than those required at the other end for the purposes of grappling 
or capturing a free-flying satellite. 
In the construction, servicing and operation of a space station, the need 
for a Mobile Servicing Center (MSC) has been recognized and it has been 
proposed that such a system should incorporate a relocatable Space Station 
Remote Manipulator System (SSRMS). In order to provide an effective SSRMS, 
the applicants have developed an end effector suitable for use with a 
Space Station Remote Manipulator System where capture and release 
capabilities are required, and which will provide for the transfer of 
substantial loads together with electrical power and signals across the 
end effector grapple fixture interface. 
The applicants have developed an end effector having a latching mechanism 
which permits the transfer of substantial loads across an end 
effector/grapple fixture interface. 
The latching mechanism of the present invention combines the known features 
of the shuttle remote manipulator system end effector with new features 
that facilitate its use in a space-station environment. 
These new features are provided in part by adapting the original shuttle 
remote manipulator system to provide orbit-maintainability. This is 
achieved in part by providing externally mounted orbit-maintainable 
latches and umbilical connectors. 
The functions associated with known nonlatching end effectors, namely, its 
snaring and rigidizing capabilities are maintained and can be operated 
independently of the new latching mechanisms and umbilical connectors. For 
this reason, the end effector of the present invention can be used in 
conjunction with existing grapple fixtures and is not limited for use with 
a new grapple fixture. 
The Space Station Remote Manipulator System End Effector of the present 
invention is capable of use in a space station assembly, payload handling 
functions, capturing free-flyers, assisting in payload servicing, and 
providing a stable base for an EVA work-station and a Manned 
Foot-Restraint. The end effector is also useful in providing a stable base 
for other robotic and dexterous devices. 
In particular, the Space Station Remote Manipulator System end effector is 
capable of operating from any suitable power data grapple fixture located 
on a mobile servicing center, a maintenance depot or any other space 
station installation. It has relocating capabilities and force moment 
accommodation capabilities. 
The end effector is capable of functioning equally as a wrist (manipulator) 
and shoulder (arm base) unit. The end effector is also able to support the 
space station remote manipulator system. 
To function as a shoulder base unit, the end effector has high strength and 
is capable of providing an extended operation life for an arm acting as a 
cantilever when serving as a payload handling, free-flyer capturing and an 
EVA work-station support system. The end effector provides a high degree 
of stiffness in order not to degrade arm control ability under difficult 
handling conditions. It is highly reliable when engaging, holding and 
disengaging from the shoulder base. It makes provision for power and 
signal transmission from the power data grapple fixture to the space 
station remote manipulator system and vice-versa. 
To permit the end effector to function at the wrist end of the Space 
Station Remote Manipulator System, it has adequate strength and stiffness 
and the ability to capture free-flyers. It also has the ability to utilize 
the strength, stiffness and power and data transfer capability of the 
shoulder base system. It will also allow for or participate in the force 
moment accommodation mode of the Space Station Remote Manipulator System 
operation. 
A further important feature of the end effector of the present invention is 
that it incorporates all the currently available capabilities of the 
existing shuttle remote manipulator system and it is of a modular design 
consisting of orbit replaceable units. 
The internal envelope of the end effector is similar to that of the 
existing Shuttle Remote Manipulator System End Effector. The external 
envelope is somewhat larger than that of the existing end effector; 
however, this is more than compensated for by the greatly enhanced 
strength and stiffness characteristics derived from the addition of the 
latching mechanisms. 
According to the present invention there is provided an end effector 
comprising; 
(a) a grapple housing having a proximal end, a distal end, a grapple 
chamber and a grapple passage opening extending from the grapple chamber 
through the distal end, 
(b) grappling means in the grapple chamber, the grapple means being for 
snaring a grapple fixture, 
(c) latching means on the exterior of said grapple housing, said latching 
means being operable to latch the end effector to the grapple fixture to 
prevent separation of the end effector and the fixture whereby substantial 
forces can be transmitted through the end effector, 
(d) first umbilical connector means mounted on said grapple housing for, in 
operation, movement towards the distal end of said grapple housing to mate 
with second umbilical cord connector means carried by a grapple fixture, 
(e) connector drive means mounted on said grapple housing for, in 
operation, driving the first umbilical connector means towards and away 
from the distal end. 
Further according to the present invention there is provided an end 
effector comprising; 
(a) a cylindrical grapple housing having a proximal end, a distal end, a 
grapple chamber having a grapple axis extending longitudinally thereof, 
and a grapple passage opening into the chamber through the distal end, 
(b) grappling means in the grapple chamber for snaring, aligning and 
rigidly securing a grapple fixture therein, 
(c) at least two latching assemblies on the exterior of the housing at 
circumferentially spaced intervals therearound, each latching assembly 
comprising; 
(i) a pair of oppositely disposed jaws pivotally mounted for movement 
between an open position and an overlapping, closed position in which they 
form a latching enclosure with the distal end of the housing, 
(ii) a threaded shaft mounted for rotation about a longitudinal axis 
extending between the jaws, 
(iii) a nut threadedly mounted on the threaded shaft for longitudinal 
movement therealong between an open position, remote from the distal end 
of the grapple housing, and a closed position more closely adjacent the 
distal end of the grapple housing, 
(iv) toggle linkage means pivotally connecting the nut and each jaw to 
cause the jaws to move to and fro between their open and closed positions 
in response to movement of the nut between the open and closed positions, 
and 
(v) a gear wheel mounted on the threaded shaft. 
(d) a ring gear extending around the said grapple housing and mounted for 
rotation therearound, said ring gear meshing with the gear wheel of each 
latching assembly, 
(e) at least one drive motor mounted on said housing, said drive motor 
having a power output shaft, and 
(f) a power output sprocket drivingly connecting the power output shaft and 
said gear ring to rotatably drive said gear ring. 
A latch support structure may be provided for each latch assembly, each 
latch support structure releasably mounting that latching assembly on the 
exterior perimeter of the housing. 
In some embodiments of the present invention the end effector may further 
comprise; 
(a) a cylindrical, latch mounting enclosure, the cylindrical, latch 
mounting enclosure having the grapple housing slidable therein, to 
telescope from a retracted position to a forward, grappling position, and 
the latching means on the exterior thereof, 
(b) a force moment sensor pivotally connected to the cylindrical, latch 
mounting enclosure, and 
(c) a torsion linkage connecting the force moment sensor to the grapple 
housing whereby the force moment sensor senses force moments between the 
cylindrical, latch mounting enclosure, and 
(d) movement restricting means for preventing further rearward movement of 
the grapple housing beyond the retracted position.

With reference to FIG. 1 of the drawings, the reference numeral 10 
generally designates a Space Station Remote Manipulator System (SSRMS). 
The Space Station Remote Manipulator System 10 is used in conjunction with 
a mobile transporter 12, shown chain dotted, which can transport the Space 
Station Remote Manipulator System 10 relative to the structure of the 
space station generally designated 14. A mobile servicing center base 
structure is generally designated 16. The SSRMS 10 can be controlled from 
an extra vehicular activity work-station 18. The system includes a power 
management distribution system 20, power data grapple fixture 22, payload 
accommodation 24, mobile transporter interface 26 and data management 
system 28. Battery packs 30 are also provided. Closed circuit television 
cameras 32 are mounted on the arms of the SSRMS 10 as are arm electronics 
packs 34. A special purpose dexterous manipulator 36 and a universal 
service tool 38 are also provided. 
End effectors 40 constructed in accordance with an embodiment of the 
present invention are mounted at each end of the arm assembly 41. 
The end effector 40 is more clearly illustrated in FIG. 2 of the drawings 
to which reference is now made. 
In this embodiment, the end effector 40 incorporates a snare mechanism 
similar to that of the end effector described in U.S. Pat. No. 4,105,241 
and so a detailed description of the snare mechanism is not necessary. The 
end effector of the present invention is capable of snaring and aligning a 
grapple fixture 22 in a similar manner to that described in the U.S. Pat. 
No. 4,105,241. As will be described later, the end effector may also 
incorporate a force moment sensor which can be used to achieve alignment 
of the end effector and grapple fixture without the aid of a grapple 
mechanism. As shown in FIG. 2, the end effector 40 includes a 
cylindrically-shaped grapple housing 42 which has a proximal end 44 and a 
distal end 46. A mounting flange 48 projects radially outwardly at the 
proximal end 44 and is formed with mounting poles 50 which are used to 
connect the housing 42 to the arm of a remote manipulator (not shown). The 
grapple housing 42 is formed with a grapple chamber 52 therein and a 
grapple passage 54 opens from the grapple chamber 52 through the distal 
end face 47 of the housing. As shown in FIG. 2, the grapple mechanism, 
which is generally designated by reference numeral 56, includes three 
snare cables two of which are shown and designated 58. As previously 
indicated, this grapple mechanism is similar to that described in U.S. 
Pat. No. 4,105,241 and will not therefore be described in detail. Three 
circumferentially spaced arcuate-shaped pockets 60 are formed at the 
distal end of the housing 42. 
FIG. 3 shows a grapple fixture, generally designated 300, which, as will be 
described later, may have a probe 320 snared by the snare cables 58, 
trunnions 310 gripped by the latches 62 to draw the grapple fixture in to 
the housing 42 until, as shown in FIG. 4, locating shoulders 310 on the 
grapple fixture 300 are located in the pockets 60 and end face 318 is in 
contact with end face 47. 
In FIGS. 2 and 4, three latch assemblies 62 are provided. Each latch 
assembly 62 comprises a support structure in the form of a frame 64 which 
is removably mounted on the outer face 66 of the grapple housing 42. The 
latch assemblies 62 are circumferentially spaced around the outer face 66. 
An electronic module 68 is also mounted on the outer face 66 of the 
grapple housing 42. The electronic module 68 is provided for controlling 
the operation of the latches 62 and an umbilical connector mechanism which 
will be described later. 
In FIG. 2, two electrical connector assemblies 176 are mounted on the outer 
face 66 of the grapple housing 42 at circumferentially spaced intervals 
therearound. A motor module 72 is also releaseably mounted on the outer 
face 66 of the grapple housing 42. Ring gears 76 and 172 are mounted on 
the grapple housing 42 and extend circumferentially around the outer face 
66 thereof. The ring gears 76 and 172 are each connected to power output 
pinions (not shown) which are mounted on the power output shaft of the 
motor 72. The power output pinions are each provided with a clutch which 
can be operated selectively to cause either of the power output pinions to 
be driven to drive the ring gear with which it is meshed so that either 
one of the ring gears 76 or 172 may be driven. 
Each of the latch assemblies 62 has a latch pinion 82 which meshes with the 
ring gear 76, which is an umbilical ring gear, such that the latch 
assemblies 62 are actuated simultaneously by the motor module 72. It will 
be understood that because this mechanism is to be used with the space 
station 14 (FIG. 1), a second motor module assembly (not shown) is 
provided in close proximity to the second electrical connector such that 
in the event of failure of one motor module, the other may be activated. 
As shown in FIG. 5, each latch assembly 62 comprises a support frame 64 
formed with a flange 90 and a bridge member 92 which projects from one 
side of a base 94. As shown in FIG. 6, a bracket 96 also projects from a 
distal end of the base 94. The bracket 96 includes a platform 100 and a 
pair of bracing flanges 102, each of which is formed with a lug 104 which 
projects laterally inwardly to provide a stop for limiting the travel of a 
ballscrew nut 106 as will be described hereinafter. 
The latch assemblies 62 are modular so as to be easily removed from the 
grapple housing 42. 
In FIG. 6, which shows the position of the grapple housing 42 when each 
latch assembly 62 is in the opened position, the latch assembly is shown 
comprising a ball screw shaft 98 which has one end supported for rotation 
in a bearing (not shown) mounted in the flange 90. The distal end of the 
ball screw shaft 98 is mounted in a bearing 99 which is supported on the 
underside of the platform 100. 
Referring once again to FIGS. 5 and 6, an umbilical connector mechanism is 
generally designated by the reference numeral 160. As will be described 
later, the umbilical connector mechanism 160 in operation connects an 
umbilical cord, carried by an end effector, across an interface formed 
between that end effector and the grapple housing 42. As shown in FIG. 6, 
pairs of flanges 162 and 164 project laterally from opposite sides of the 
grapple housing 42 and a pair of shafts 166 are mounted for rotation in 
the flanges 162 and 164. A pinion 168 is mounted on each shaft 170 which 
is supported by the corresponding flange 164. Each pinion 168 is meshed 
with the ring gear 172 which is mounted for rotation on the grapple 
housing 42. A gear train 74, 174 and 80 serves to connect the drive shaft 
170 to the shaft 166 such that when the ring gear 172 is rotatably driven 
the shaft 166 will be rotatably driven. Rotation of the drive shaft 166 
will cause the connector member 176 which is mounted thereon to move, as 
will be described later, toward and away from an interface to mate with a 
complimentary connector element carried by the grapple fixture 22 as will 
be described hereinafter. 
As shown in FIG. 7, the ballscrew nut 106 is threadedly mounted on the 
ballscrew 98 such that rotation of the ballscrew 98 about its longitudinal 
axis 108 causes the ballscrew nut 106 to move along the axis 108. 
Latching levers and their associated toggle mechanism are best illustrated 
in FIGS. 7, 8 and 9 read in conjunction with FIG. 6. As shown in FIG. 7, 
the toggle mechanism includes a pair of first link arms 110 which have 
their proximal ends pivotally mounted on a pivot pin 112 for rotation 
about a first axis 114. The pivot pin 112 is mounted on the ballscrew nut 
106. A pair of second link arms 116 each have their proximal ends 
pivotally mounted on pivot pins 118 which are supported by the bridge 92 
of the frame as shown in FIG. 6. The second link arms 116 are free to 
pivot about second axes 120. The distal ends of the first and second link 
arms 110 and 116 are pivotally connected for movement about third axes 122 
by means of pivot pins 124. A pair of third link arms 126 each have their 
proximal ends pivotally connected to a pivot pin 124 for movement about 
the axes 122. 
The latching assembly also includes bell-crank latching jaws 123 and 125. 
The latching jaws 123 and 125 have latch arm portions 130 and 132 
respectively and lever arm portions 134. As shown in FIG. 2 of the 
drawings, the latch arm 132 is a single arm and the latch arm 130 is 
bifurcated to provide a notch 136 which will receive the single arm 132. 
A bridging link 138 (FIGS. 7 and 8) is pivotally connected to the proximal 
ends of the lever arms 34 of the latching jaws 123, 125 for movement about 
fourth axes 140. 
The elbows 142 of the latching jaws 123, 125 are pivotally connected to the 
distal end of each third link arm 126 for movement about fifth axes 144. 
Because both ends of each third link arm 126 are pivotally mounted, 
allowance is made for the latching jaws 123, 125 and the bridging link 138 
to conform to deflections of grapple fixture trunnions which will be 
described later. 
By rotatably driving the ballscrew 98, the ballscrew nut 106 can be driven 
to and fro between its fully retracted position illustrated in FIG. 2 of 
the drawings and its extended position shown in FIG. 9 of the drawings. 
FIG. 7 of the drawings shows the position which the latching jaws 123, 125 
will assume after capture of a grapple fixture trunnion 310. When in this 
position, it will be noted that the third axes 122 are located inwardly of 
their center lines 146 which intersect the associated second axis 120 and 
fifth axis 144. Further movement of the ballscrew 98 toward the fully 
extended position will cause the axis 122 to approach and eventually 
become aligned with the center line 146 as shown in FIG. 8. Thereafter, 
further movement of the ballscrew 98 toward its fully extended position 
will cause the axis 122 to be displaced laterally outwardly from the 
center line 146. This is the position which the linkage assembly will 
assume when the ballscrew nut 106 is in its fully extended position 
bearing against the lugs 104 as shown in FIG. 9. In this configuration, 
the linkage mechanism is located in an overcenter condition which will not 
permit back driving of the ballscrew 98 because the application of a load 
tending to open the latching jaws 127, 129 will be applied to the 
ballscrew nut 106 through the linkage so that it will tend to urge the 
ballscrew nut 106 toward the arresting lugs 104 and not away from the lugs 
104. 
In order to eliminate backlash in the linkage assembly, a compression 
spring assembly 150 is provided. The compression spring assembly 150 
consists of a stack of Bellville washers 152 which are compressed between 
a support plate 154 and the underside of the platform 100. A shaft 156 
(FIG. 8) has one end connected to the support plate 154 and its other end 
connected to the bridging link 138. The shaft 156 extends through the 
Bellville washers 152 such that when the bridging link 138 is raised from 
the platform 100, the Bellville washers 152 will be further compressed 
between the platform 100 and the support plate 154. Although only one set 
of Bellville washers is illustrated in the drawings, it will be understood 
that two sets are actually provided with one set being located behind the 
ballscrew shaft 98 in relation to the view illustrated in FIG. 7. This 
serves to ensure that the bridging link 138 will not be subjected to 
twisting loads when it is raised above the platform 100. 
In use, the Bellville washers 152 are precompressed when the bridging link 
138 is resting on the platform 100 as shown in FIG. 7. The trunnion 310 
cannot be moved relative to the end effector 40 (FIG. 1) after it has been 
captured and assumes the position shown in FIG. 7, because the linkage 
mechanism must yield in order to permit the latching jaws 123, 125 to move 
from the position shown in FIG. 7 to the over-center position shown in 
FIG. 9. The yielding of the linkage assembly is achieved by reason of the 
fact that the Bellville washers 152 can be compressed to permit the bridge 
link 138 to be elevated. By reason of the fact that the latch assembly 
linkage is capable of yielding, it is possible to contour the inner faces 
127 and 129 of the latching jaws 123, 125 respectively so that they have a 
concave arc of curvature which serves to center and retain the trunnion 
310. The compression of the springs to provide a load ensures that the 
grapple fixture end effector interface will remain in a highly loaded 
condition to form a stiff connection that is free of any play. 
As shown in FIG. 6 of the drawings, when the latching jaws 123 and 125 are 
in the fully opened position, a major portion of their length is spaced 
rearwardly from the end face 47 of the housing 42 so that it does not 
obstruct access to the grapple passage 54 (FIG. 1). 
In use, by rotatably driving the ring gear 172 in a first direction, the 
latching jaws 123, 125 can be moved from their fully opened position 
illustrated in FIG. 6 to their fully closed position illustrated in FIG. 9 
and by rotatably driving the ring gear 172 in the opposite direction, the 
latching jaws can be opened from the closed position. 
The connector member 176 is illustrated in FIGS. 10 and 11 of the drawings. 
As shown in FIG. 10, the connector 176 consists of a connector plug member 
178 which is mounted on a support plate 180. The support plate 180 in turn 
is mounted on the face plate 182 of the carrier assembly which is 
reciprocally driven by the umbilical drive mechanism by way of its 
rotatable drive shaft. The support plate 180 has a pair of sleeve bearings 
184 mounted therein through which shafts 186 extend. The shafts 186 are 
secured to the face plate 182 by mounting screws 188. A compression spring 
190 is located between the head portion 192 of the shaft 186 and the 
sleeve 184 so as to normally urge the support plate 180 and its plug 
member 178 toward the face plate 182. As shown in FIG. 11, the mounting 
screws 188 and their associated shafts 186 are located at diagonally 
opposite corners of the face plate 180. Guide pins 194 are located at the 
opposite corners of the support plate 180 and project forwardly therefrom 
through passages 196 formed in the face plate 182. 
The complementary connector 197 carried by a grapple fixture is shown in 
detail in FIGS. 12 and 13. The complementary connector 197 consists of a 
support plate 198 which supports a socket member 200 which is adapted to 
mate with the plug member 178 (FIGS. 10 and 11) in order to form a 
connection therewith. Guide sockets 202 are mounted on the support plate 
198 and are arranged to receive the guide pins 194 to align the plug 
member 178 with the socket member 200. Mounting screws 204 are provided 
for the purposes of mounting the support plate 198 with respect to a 
grapple fixture 22. 
Turning now to FIG. 14 of the drawings, it will be seen that the umbilical 
connector mechanism includes a ballscrew nut 206 which is connected to the 
connector housing 208 and is threadedly mounted on a ballscrew 210. The 
ballscrew 210 is rotatably driven through the power train pinions 78 and 
80. The pinion 74 is connected to the pinion 78 through the shaft 75 so 
that when the umbilical cord ring gear 76 of FIG. 2 is rotatably driven, 
the ballscrew shaft 210 will be rotatably driven and this in turn will 
cause the ballscrew nut 206 to be driven longitudinally to move the 
connector housing 208 between the position shown in solid lines in FIG. 14 
and the position shown in dashed lines. The umbilical cord 212 is 
connected to the plug member 178 for movement therewith. A bridge 214 is 
provided for guiding the umbilical cord 212 over the gear rings. The 
connector housing 208 is slidably mounted on guide rails 209 for 
longitudinal movement with respect to the grapple housing 42. 
FIGS. 5 and 15 show a force moment sensor, generally designated 220, which 
is provided to facilitate the initial alignment of the end effector with 
respect to the grapple fixture 22 and to monitor the light loads 
transmitted through the grapple fixture 22 when the latch assemblies 62 
are disengaged. The force moment sensor 220 consists of a central shaft 
222 which has four arms 224 projecting radially therefrom. The outer ends 
of the arms 224 are each fitted with spherical end portions, such as that 
shown and designated 226 in FIG. 15, which are seated pivotally in 
receptacles 228. Strain gauges (not shown) are mounted on the arms 224 to 
function as sensors. The receptacles 228 are secured with respect to a 
cylindrical latch mounting enclosure 230 (FIG. 15). The spherical end 
portions 226 serve to prevent transmission of some of the forces which are 
sensed by the force moment sensor 220 to the enclosure 230. These forces 
could otherwise cause an incorrect reading to be generated by the force 
moment sensor 220. It will be understood that the spherical end pieces 
could be replaced by "flexures" which can provide more accurate force 
moment sensor readings. A conical-shaped housing 232 is secured to a force 
moment sensor base plate 234 which in turn is secured to the proximal end 
44 of the grapple housing 42. A spherical bearing 236 is mounted in the 
force moment sensor base plate 234 and a linear bearing 238 is mounted in 
the spherical bearing 236. Similarly, a spherical bearing 240 is mounted 
at the upper end of the conical housing 232 and a linear bearing 242 is 
mounted in the spherical bearing 240. The central shaft 222 has a lower 
end portion 244 of reduced diameter mounted in the linear bearing 238 and 
an upper end portion 246 of reduced diameter mounted in the linear bearing 
242. The upper end portion 246 of the shaft has a threaded end portion 248 
threadedly mounted in a bridge member 250. A pair of spaced parallel guide 
pins 252 are mounted in the end flange 254 which is located at the upper 
end of the conical-shaped housing 232. Compression springs 256 are 
compressed between the flange 254 and the bridge plate 252 to urge the 
bridge plate 252 away from the conical-shaped housing 232. A torsion 
linkage 258 connects the lower end of the central shaft 222 to a bracket 
260 which is mounted on the force moment sensor base plate 234. 
In use when a load is encountered which is in excess of that which the 
force moment sensor is designed to detect, the grapple housing 42 will 
move longitudinally with respect to the external latch mounting enclosure 
230 by compressing the springs movement restricting means in the form of a 
flange 262, which is located at the proximal end of the grapple housing 
42, comes in contact with the flange 264, which is located at the distal 
end of the external latch mounting enclosure 230, so that any further 
forces which are applied to the grapple housing 42 will be transmitted by 
the flanges 262 and 264 to the external latch mounting enclosure and so no 
additional load will be applied to the force moment sensor 220. 
It will be understood that this telescoping of the grapple housing 42 with 
respect to the external latch mounting enclosure 230 will occur when the 
latching mechanism is activated and consequently, the force moment sensor 
will be locked out of the system when the latches are activated to latch 
the end effector 40 to the grapple fixture 22. 
In FIG. 3, a grapple fixture generally designated 300 is shown which is 
suitable for use with the latching end effector 40. The grapple fixture 
300 may be used as the powered data grapple fixture 22 illustrated in FIG. 
1 or it may be attached as a grapple fixture to a payload or the like. The 
grapple fixture 300 has an end plate 302 which may be used for the 
purposes of mounting it on the payload or the like. An arm 304 projects 
radially outwardly from the end plate 302 and has an alignment target 306 
located thereon. The grapple fixture 300 also has a base portion 308 
projecting from the base plate 302 and latch trunnions 310 projecting 
radially from the base 308. The trunnions 310 are equally spaced 
circumferentially and are alignable with the latching jaws 123, 125 (FIGS. 
6 to 9) of the end effector 40. A cylindrical extension 312 projects from 
the end of the base 308 and three rounded locating shoulders 314 project 
radially from the cylindrical portion 312 and are equally spaced 
circumferentially therearound. The locating shoulders 314 fit in a close 
fitting relationship within the pockets 60 of the end effector 40 (FIG. 
2). The locating shoulders 314 are rounded so as to be self-centering when 
entering the pockets 60. A locating and aligning cone 316 projects from 
the outer end of the cylindrical extension 312. A grapple probe 320 
projects from a distal end of the cone 316 and has an enlarged head 
portion 322 at the outer end thereof. The base portion 308 has an abutment 
end face 318 which in use is arranged in an end to end relationship with 
the distal end face 47 of the end effector 40. 
As shown clearly in FIG. 3 of the drawings, the trunnions 310 each have a 
generally flat outer face 324 and a rounded back face 326. 
An electrical connector housing 328 (FIG. 3) is mounted on the base 308 and 
projects radially outwardly therefrom. In FIG. 3, two socket members 200 
(of the type shown in FIGS. 12 and 13) are mounted in the housing 308 for 
alignment with complementary plug members 178 mounted in the electrical 
connectors 70 (FIGS. 2, 10, 11 and 14) of the end effector 40. 
FIG. 4 of the drawings illustrates the latched position of the end effector 
40 and grapple fixture 300. In this position, the latch assemblies 62 are 
in the closed position embracing the trunnions 310 and the umbilical 
connections are made. 
FIG. 16 of the drawings is a functional and interface diagram, the legend 
of which is illustrated in FIG. 17 of the drawings. FIGS. 18 and 19 are 
diagrams illustrating the force moment sensor options to which the legend 
of FIG. 18 also applies. 
In use, the end effector 40 may be mounted at one or both ends of a device 
such as the remote manipulator arm 42 and any number of grapple fixtures 
300 may be mounted at locations accessible to the manipulator arm 42. Each 
of the grapple fixtures 300 which are intended to provide a shoulder 
connection for the remote manipulator arm will also be provided through 
their umbilical cord system with a source of power and/or with a control 
station. As a result, when the end effector is mated with the grapple 
fixture to form a shoulder connection, command signals can be transmitted 
through the interface between the end effector and the grapple fixture 
which will serve to control the movement of the remote manipulator arm. In 
addition, because it is possible to latch the end effector to the grapple 
fixture, substantial loads can be applied to the shoulder joint without 
damaging the shoulder joint. 
The grapple fixture 300 can also be mounted on a free-flyer or a payload 
item which does not require power or command signals to be transmitted 
through the end effector grapple fixture interface. In such an 
application, it is not necessary to provide the socket members 200 in the 
grapple fixture 300. 
FIGS. 1 and 20 to 24 illustrate the use of the end effector 40 and grapple 
fixture 300 in association with a stationary payload such as the space 
station 14 (FIG. 1). In this configuration, it is possible to utilize the 
force moment sensor 220 (FIGS. 5 and 15) of the end effector 40 to obtain 
alignment without using the snare or grapple mechanism. In use, the arm 41 
(FIG. 20) is commanded to move the end effector 40 along its longitudinal 
axis. As the inside diameter of the end effector 40 contacts the outside 
of the cone 316, the force moment sensor 220 generates a feedback signal 
which causes the arm 41 to move the end effector laterally to adjust its 
alignment with the cone 316. Some angular improvement in alignment is also 
provided by the force moment sensor as the end effector pockets 60 (FIG. 
2) contact the locating shoulders 314 which protrude beyond the cone 316. 
The angular alignments, however, may require some assistance from the arm 
operator who will use the closed circuit television cameras 32 (FIG. 1) 
mounted on the arm 41 such that its position is fixed for the end effector 
to view the alignment target on the grapple fixture. The operator 
assistance may be required to assist the force moment sensor to achieve 
angular alignment because of the complexity of angular alignments in three 
dimensions. 
As shown in FIGS. 1 and 20 of the drawings, the end effectors 40 may be 
located at each end of the manipulator arm assembly 41 of a space station 
remote manipulator system 10 such that one end effector 40 is connected to 
the mobile service center 16 while the other is secured to a stationary 
payload item 340. If, however, the system is to be used to capture "free 
flyers", which do not offer the stability of a stationary payload, it is 
then necessary to use the snaring capability of the end effector. In this 
case the manipulator arm 41 is initially manipulated into a position such 
as that illustrated in FIG. 21 in which the probe 320 (FIG. 3) of the 
grapple fixture 300 extends into the grapple passage of the grapple 
housing 42; it is then possible for the snaring cables 58 (FIG. 2) to be 
activated so that they engage the probe. This snaring action will serve to 
further align the end effector 40 with the grapple fixture 300 and draw 
the two together. While the arm 41 is capable of being back driven by 
forces exerted during snaring and rigidizing without the use of the force 
moment sensor 220 (FIGS. 5 and 15), the use of the force moment sensor 220 
may allow the arm to better respond to accommodate itself to free flying 
payloads by reacting faster and increasing the arm compliance. 
Conventional arms 41 are left in a limp mode during the snaring and 
rigidizing sequence for free flyers by lowering the current to the motors 
at the joints to a minimum value which allows the joints of the arms 41 to 
be back-driven while still offering some resistance to joint movement. If 
the force moment sensor 220 is used, contact between the end effector 40 
and the alignment cone 316 will activate the force moment sensor 220 and 
cause it to generate a signal which can be interpreted by a control system 
to generate alignment correction commands to the various powered joints of 
the arm 41 so that the arm 41 will be manipulated to bring the end 
effector 40 more closely into alignment with the grapple fixture 300. 
FIG. 22 of the drawings illustrates the relative positions of the end 
effector 40 and the grapple fixture 300 when aligned with one another and 
with the latches 62 open. The latches 62 are then closed around the 
trunnions 310 as shown in FIG. 23. The umbilical connector mechanism 160 
(FIGS. 5 and 6) is then activated to cause the plug members 178 (FIGS. 10 
and 11) to mate with their socket members 202 (FIGS. 12 and 13) as shown 
in FIG. 24. 
Various modifications of the present invention will be apparent to those 
skilled in the art. It will, for example, be apparent that while three 
latching trunnions 310 are shown together with three latch assemblies 62, 
it may be possible in some circumstances to achieve the required 
connection using only one trunnion and one latch or in some cases using 
two trunnions 310 and two latches 62. The number of trunnions 310 and 
latches 62 which are used is not critical. Similarly, any number of 
electrical connectors may be provided. These and other modifications of 
the present invention will be apparent to those skilled in the art.