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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to apparatus for deploying an articulated panel
array.
2. Description of the Related Art
Heretofore, in deploying the panels of a satellite solar panel array, two
basic approaches have been taken. Firstly, some deployment systems do not
kinematically link neighbouring panels so that the panels deploy
independently. With this approach, the deployment mechanism is
mechanically relatively simple but the deployment trajectories of the
elements are ill-defined. Hence, a great deal of uncertainty exists as to
the transient geometry of the deploying array. This is disadvantageous as
it risks the array knocking into other portions of the satellite during
deployment.
The second approach used in deploying a satellite solar panel array
kinematically links neighbouring panels with a coordinating device
(comprising cables, pulleys or the like). While a coordinating device
should provide a more defined deployment geometry, in practice, because of
the finite stiffness of the coordinating linkage, sufficient divergence
occurs between the theoretical and actual deployment envelopes as to
potentially cause difficulties. Furthermore, the linkage mechanism of the
coordinating device itself adds to the weight, cost and complexity of the
satellite. Furthermore, the increased complexity reduces the overall
reliability of the mechanical assembly.
The subject invention seeks to overcome drawbacks of known satellite solar
panel array deployment apparatus by providing apparaus which offers a
well-defined deployment trajectory while avoiding the use of coordinating
linkages.
SUMMARY OF THE INVENTION
According to the present invention, there is provided apparatus for
deploying an articulated panel array having a support end for mounting to
a support and a distal end, of the array urging the panel of any
articulated panel pair which is closer to said distal end to a deployed
position with respect to the panel of the pair which is closer to said
support end; a latch between each panel pair to retain the panel of the
pair which is closer to said distal end in an undeployed position with
respect to the panel of the pair which is closer to said support end; for
any given panel pair other than the pair which is closest to said support
end, a latch release associated with the panel next adjacent the given
panel pair and toward said support end, said latch release releasing said
latch between said given panel pair upon the panel of said panel pair
which is closer to said support end moving to a deployed position with
respect to said next adjacent panel; and controllable means to release the
latch of the panel pair which is closest to said support end, whereby said
panels are sequentially deployed once the latch of the panel pair which is
closest to said support end is released.
BRIEF DESCRIPTION OF THE DRAWINGS
In the figures which disclose example embodiments of the invention,
FIG. 1 is a schematic perspective view illustrating a satellite equipped
with a solar panel array deployment apparatus made in accordance with this
invention,
FIG. 2 is a schematic perspective view of the satellite of FIG. 1 showing
the panel array in a deployed position,
FIGS. 3a through 3d are schematic illustrations showing the operation of
the solar panel deployment mechanism of this invention,
FIG. 4 is a perspective view of a solar panel array incorporating the
deployment mechanism of this invention,
FIG. 5 is a plan view of a solar panel array equipped with the deployment
mechanism of this invention, and
FIGS. 6 and 6a are side views of a portion of a solar panel array
incorporating the deployment mechanism of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to FIG. 1, a satellite 10 has two solar panel arrays 12 and
14 depending therefrom. FIG. 1 illustrates the panel arrays in a stored
position. FIG. 2 shows the same arrays 12 and 14 in a deployed position.
Each array comprises a series of solar panels 16 which are hinged together
by spring motors 24. Considering panel array 14, the proximal end 18 of
the array is mounted on the support 20 which is part of the body of the
satellite. This support may be a hinged support (as illustrated in FIG. 2
at 20) or a rigid support (as illustrated in FIGS. 4 and 5 at 120). The
panel array also has a distal end 22 (FIG. 2).
With reference to FIGS. 3a through 3d, as will become apparent hereinafter,
the deployment mechanism of the subject invention allows for the automatic
sequential deployment of the panels of the array. Thus, from the
undeployed position illustrated in FIG. 3a, panel array 14 may be deployed
with the group of panels sequentially unfolding from the most proximally
disposed panel of the group (FIGS. 3b and 3c) until the most distally
disposed panel 16d unfolds from the adjacent more proximally disposed
panel 16c (FIG. 3d).
The details of the deployment mechanism of this invention are now described
with reference to FIGS. 4 through 6. However, at the outset, it should be
noted that during deployment, the panel array never attains the position
illustrated in FIG. 4. The position of the array illustrated in FIG. 4 was
chosen merely to clearly reveal the details of the structure of the array.
With reference to FIG. 4, spring motors 24b, 24c, and 24d are provided
between each adjacent pair of panels 16a-16b, 16b-16c, and 16c-16d,
respectively. The spring motors not only hingedly connect panel pairs but
also provide the motive force for deploying the panels. The nature of the
spring motors 24b, 24c, 24d is described in detail in U.S application Ser.
No. 07/850,319 now U.S. Pat. No. 5,265,853, the disclosure of which is
incorporated herein by reference.
Each spring motor is biased so that, considering any panel pair, the spring
motor tends to urge the more distally disposed panel of the pair to a
deployed position with respect to the more basely disposed panel of the
pair.
With reference to FIG. 5 as well as FIG. 4 and considering panel pair
16b-16c, panel 16c has a hook 26c mounted thereto at pivot 28. The hook is
biased to a latching position by a spring 30. The hook may be received
within a receptor 32b in panel 16b and hook to panel 16b at flange 33b
defining the edge of the receptor in order to retain panel 16c in an
undeployed position with respect to panel 16b. Together, the hook and
receptor act as a latch between panel pair 16b-16c. A similar latch
(comprising hook 26d and receptor 32c) is associated with panel pair
16c-16d.
A plunger 34b is slidably supported on panel 16b so that it may be extended
across the receptor 32b. The plunger is biased to an inoperative retracted
position by spring 36b.
A latch release in the nature of abutment 38a is supported on panel 16a so
that when panel 16b moves to a deployed position with respect to panel
16a, the abutment abuts the rear end 40b of plunger 34b and pushes the
plunger to an operative extended position against the force of spring 36b.
A similar latch release (comprising abutment 38b) is associated with panel
16b.
As seen in FIG. 4 and 6a, panel pair 16a-16b has a lock comprising a
locking member 42a and a locking pin 44b. The locking member 42a is
pivotally mounted to panel 16a and is spring biased by spring 46b to a
locking position; in FIGS. 4 and 6a, the locking member is illustrated in
this locking position. The locking member has a notch 49a and a ramp face
48a. The ramp face is in the path of pin 44b when the locking member 42a
is in its locking position. Locking pin 44b is rigidly affixed to panel
16b. A similar lock is associated with each of the other panel pairs
16b-16c and 16c-16d.
Panel 16a also has an energy absorbing stop 50a mounted thereto and panel
16b has a similar energy absorbing stop 52b mounted thereto in the path of
stop 50a such that the two stops abut as panel 16b moves to the deployed
position with respect to panel 16a. Panel pair 16b-16c has similar stops
50b, 52c as does panel pair 16c-16d (stops 50c and 52d).
Panel 16a has an operator controlled latch 54a to hold panel 16b in an
undeployed position with respect to panel 16a.
The operation of the apparatus of this invention will now be explained in
connection with the FIGS. 5, 6, and 6a as well as figure series 3a through
3d. With the panel array in its undeployed position illustrated in FIG. 5
and (schematically) in FIG. 3a, operator controlled latch 54a may be moved
to release panel 16b. Once this occurs, panel 16b begins to move toward
its deployed position under the urging of spring motor 24b. However,
because panel 16c is held in an undeployed position with respect to panel
16b by hook 26c and panel 16d is held in an undeployed position with
respect to panel 16c by hook 26d, panels 16b through 16d rotate about the
axis of spring motor 24b as a group. This is illustrated in phantom in
FIG. 5. With reference to FIG. 6, as panel 16b nears its deployed
position, abutment 38a approaches the head 40b of plunger 34b. When panel
16b reaches its deployed position, as illustrated in FIG. 6a, abutment 38a
has pushed plunger 34b against hook 26c in order to disengage the hook
from the flange 33b of the receptor 32b. This releases panel 16c from
panel 16b so that panel 16c may begin to move a deployed position under
the influence of spring motor 24c. It will be noted, however, that panel
16c will not begin to deploy until the moment when plunger 34b disengages
hook 26c from the flange 33b of panel 16b.
Returning to a consideration of FIG. 6a, as panel 16b approaches its
deployed position, pin 44b ramps up the ramp face 48a of locking member
42a. This displaces the locking member from its locking position allowing
the pin to enter notch 49a of the locking member 42a whereupon the locking
member is urged back to its locking position in order to retain pin 44b
within notch 49a and hold panel 16b in its deployed position.
The act of pin 44b moving along ramp face 48a and displacing locking member
42a from its locking position against the urging of spring 46a absorbs
some of the kinetic energy imparted to panel 16b by spring motor 24b. The
remaining kinetic energy is absorbed by stops 50a and 50b which abut when
panel 16b has moved to its fully deployed position with respect to panel
16a.
Once panel 16b has moved to its fully deployed position (FIG. 3b), the
latch between panels 16b and 16c will be released and panel 16c will then
move to its fully deployed position with respect to panel 16b (FIG. 3c).
While panel 16c is rotating about the axis of spring motor 24c, panel 16d
rotates with panel 16c by virtue of the latch between this panel pair.
Finally, when panel 16c reaches its fully deployed position, the latch
between panel pair 16c-16d is released and panel 16d moves to its fully
deployed position with respect to panel 16c as seen in FIG. 3d.
Accordingly, it will be apparent that the present invention provides a
well-defined deployment envelope. Indeed, the only uncertainty in the
envelope results from the finite stiffness of individual panel members.
That is, individual members will flex slightly during deployment. However,
this effect is extremely small.
Since during deployment, a group of panels moves together the energy to be
absorbed by the structure at any given time is, at most, that imparted by
one spring motor. Thus, the energy which must be dissipated is minimized.
A further advantage of the system is that it minimizes deployment time.
That is, because only one group of panels moves at a given time, the
moment of inertia "seen" by the deploying spring motor is at a minimum
because the deploying panels are the closest to the axis of rotation.
Finally, because the deploying array of this invention has only one degree
of freedom (that is, only one group of panels moves at a given time about
a hinge line) the mechanism of the invention provides for easy analytical
treatment.
Modifications will be apparent to those skilled in the art and,
accordingly, the invention is defined in the claims.
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