Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
The invention relates to an aerial support platform
mechanism for cinematographic and similar uses, more parti-
cularly to a mechanism having a platform supported to ex-
tend below and intermediate of a pair of parallel guidemembers, and having three linear axes of motion and two
rotational axes of motion.
BACKGROUND OF THE INVENTION
Various suspension systems for supporting equipment in
aerial locations are known. Such systems are particularly
important in the making of motion pictures, where cinemato-
graphic equipment has to be suspended at high elevations to
capture panoramic views. A boom mounted on a vehicle may
give the necessary height, or it may be possible to use the
roof of a nearby building. However, systems which are not
ground-based are increasingly being used, i.e. systems that
use cables or similar means for suspension. U. S. Patent
No. 4,710,819, granted to Garrett W. Brown on Dec. 1, 1987,
discloses one such system. It uses at least three flexible
members, such as cables, to suspend an equipment support
member inside of a support structure. Each of the flexible
members extends around a pulley on the support structure,
and has one end connected to the equipment support member
and the other end connected to a motor assembly controlled
by a computer. The relative movement of the flexible mem-
bers is synchronized by the computer, and this arrangement
allows a computer operator to control the position of the
support member within the support structure. A somewhat
similar concept for directing an underwater exploration de-
vice is disclosed in U.S. Patent No. 3,324,239, granted toI. C. Jacobson on June 6, 1967.
Numerous difficulties have been found to exist with
the suspension system of Brown. A major problem is stress
on the cables; because of the angles involved, supporting
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an item weighing several hundred pounds may create a ten-
sion in the cables many times higher; the cables have been
known to break under such stress. Brown's three-cable and
four-cable systems incorporate no redundancy; if a cable
breaks, the supported item freely falls. Known problems
with prior art systems are the stress placed on the motor
assemblies to which the cables connect, the motors are
under continual pressure to maintain tension on the cables,
which leads to their frequent burn out, and the creation of
wave motion in the cables; this results in serious prob-
lems for cinematographers and others who require a highly
stable camera platform with smooth movement.
The aerial support platform mechanism of the subject
invention has a redundancy built into its cable system; if
a support cable should break, a parallel drive cable takes
on the support cable load and prevents the supported item
from falling. Because the vertical cables in the subject
invention only have to carry the weight of the supported
item and are not part of the overall suspension system as
in the Brown system, those cables can be made considerably
thinner than is possible with Brown's system. That allows
the vertical cables supporting a camera on a first platform
member of the invention to be invisible to a second camera
on a second platform member, even if the separation between
the two is only a few feet. Because the motors of the sub-
ject platform mechanism only act to move carriages and not
to support cables as in Brown, the motors have little or no
burn out. The cables of the subject platform mechanism ex-
perience negligible wave motion because the start/stop por-
tion of the software that controls movement has a built-in
inertia compensation, similar to that found in modern ele-
vator control systems.
Two further prior art systems are found in U.S. Patent
5,113,768 (Brown) and U.S.Ptaent 5,225,863 (Weir-Jones).
These systems are directed solely to linear traveling and
does not permit substantive lateral or vertical
displacement of the camera system.
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SUMMARY OF THE INVENTION
The invention is an aerial support platform mechanism
having a pair of parallel first guide means, transverse
second guide means, and vertical third guide means. It
also has a pair of first carriages, each supported on a
respective one of the first guide means and having a first
movement means for moving it along the respective first
guide means. The transverse guide means extends between
the pair of first carriages, and supports a second carriage
and a second movement means for moving that carriage along
the second guide means. The vertical guide means extends
downward from the second carriage, and supports a platform
member and a third movement means for moving the platform
member relative to the third guide means. The platform
member has a frame connected to the third guide means, and
also has a platform connected to the frame. The platform
is rotatable around two axes relative to the frame by means
of a fourth and a fifth movement means. The mechanism also
has a control means for controlling movement of the first,
second, third, fourth and fifth movement means.
Each first guide means may be a cable, and each first
carriage may have a wheel means riding on the respective
cable. The second guide means may be a cable that extends
between the pair of first carriages, and the second
carriage may have a wheel means riding on that cable. The
third guide means may be a series of cables that extend
between the second carriage and the frame of the platform
member.
The platform of the platform member may be connected
to the frame for rotation around a vertical first axis and
around a second axis extending generally normal to the
first axis. A disk member may be rotatably connected to
the frame for rotation around a vertical first axis, and
the platform may be rotatably connected to the disk member
for rotation around an axis extending generally normal to
the first axis.
Each first movement means may comprise a first cable
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loop that extends between a first driven pulley and a se-
cond pulley, and connects to a respective first carriage at
a point intermediate the first and second pulleys. The
second movement means may comprise a second cable loop that
extends between a third driven pulley and a fourth pulley,
and connects to the second carriage at a point intermediate
the third and fourth pulleys. The third pulley may be se-
cured to one first carriage, and the fourth pulley may be
secured to the other first carriage. Alternatively or ad-
ditionally, the third and fourth pulleys may be secured torespective opposite ends of the second guide means.
An extended aerial support platform mechanism may com-
prise a series of the basic platform mechanisms described
above, each of the basic mechanisms having a single common
first guide means.
SHORT DESCRIPTION OF THE DRAWINGS
The platform mechanism of the invention will next be
further described by means of a preferred embodiment, uti-
lizing the accompanying drawings, in which:
Figure 1 is a perspective view of the aerial support
platform mechanism of the invention;
Figure 2 is a perspective view of three of the aerial
support platform mechanisms situated in close proximity;
Figure 3 is a side view of the aerial support platform
mechanism of Figure l;
Figure 4 is a top view of the aerial support platform
mechanism of Figure l;
Figure 5 is an enlarged view of a segment of the top
view of Figure 4;
Figure 6 is a perspective view of a first carriage and
the first and second guide means;
Figure 7 is a side view of the two first carriages,
the second carriage, and the second guide means for moving
the second carriage;
Figure 8 is an enlarged view of a first carriage, the
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second carriage, and a motor for moving the second carriage
on the second guide means;
Figure 9 is a top view of the two first carriages, the
second carriage, and the second guide means of Figure 7;
Figure 10 is a perspective view of the second carri-
age, the third guide means and the platform member;
Figure 11 is an end view of the second carriage, the
third guide means and the platform member of Figure 10;
Figure 12 is a schematic diagram of the control system
utilized to operate the three aerial support platforms of
Figure 2; and,
Figure 13 is a perspective view of the platform mech-
anism built into a truss hoistable by a pair of cranes.
DESCRIPTION OF A PREFERRED EMBODIMENT
A form of the aerial support platform mechanism that
is used to support a camera in a studio is shown in Figure
1. A pair of guide cables 14 and 16 each extend across a
respective one of a pair of facing side walls 18 and 20 of
the studio. One end of guide cable 14 is fixed to a first
end wall 21 by a bracket 22. The other end of cable 14 is
connected to a first end of a turnbuckle 24, the other end
of which is fixed by a bracket 25 to a second end wall 26.
The guide cable 16 is similarly supported on the other side
wall 20. In this embodiment the guide cables 14 and 16 are
each approximately fifty feet in length.
Riding on guide cable 14 is a carriage generally de-
signated 30; a similar carriage 31 rides on guide cable 16.
As illustrated in Figures 5 and 6, the carriages 30 and 31
are each formed by a pair of generally rectangular plates
32 with a pair of angled corners. Plates 32 are held in
parallel spaced relation by a series of spacers 34 mounted
between them; each spacer 34 is secured to each plate 32 by
a screw 36. Rotatably mounted between the plates 32 are a
pair of large pulleys 38 and a pair of small pulleys 40. A
series of holes 42 are positioned around the periphery of
each plate 32.
A pair of cables 44 extend between the two carriages
30 and 31. Each end of each cable 44 terminates in a loop
45 that extends around one of the spacers 34 mounted
between the pair of plates 32. Each cable 44 is connected
to a turnbuckle 46 which, when rotated, increases the
tension on the cable. As illustrated in Figure 9, a
carriage assembly 48 formed by a pair of carriages 50 each
of similar construction to the carriages 30 and 31, rides
on the pair of cables 44. The two carriages 50 are held in
parallel, spaced relation by a series of struts 52.
Each of the carriages 30 and 31, and the carriage
assembly 48, moves by means of a respective cable loop,
held between a pulley and a motor shaft, as shown in
Figures 3 and 4. With respect to the carriages 30 and 31,
a cable 56 connects to one side of each carriage, extends
around a pulley (not shown) on a shaft of a motor 58,
around a pulley 60, and then connects to the other side of
the respective carriage. The motor 58 is mounted on the
end wall 21 by a bracket 62. The pulley 60 is connected
through a spring member 64 to a turnbuckle 66, which is
secured to the end wall 26 by a bracket 68. A clamp 69 on
the top of motor 58 secures the guide cable 14 to the
motor. If the cable 14 breaks, the cable 56 prevents the
carriage 30 from falling and supports that carriage until
repairs are made.
A cable 70 connects to one of the struts 52 between
the pair of carriages 50, extends around a pulley (not
shown) on the shaft of a motor 72, extends around a pulley
74, and then connects to the another of the struts 52. As
seen in Figs. 6, 7 and 8, the motor 72 is secured to the
carriage 30 by a pair of struts 76, and is secured to the
cables 44 by a bar 77. The pulley 74 is secured to a
spring member 78, which in turn is secured to the carriage
31. Since the position of motor 72 changes as it moves
across wall 18, a helical power line 80 is used to connect
motor 72 to a ceiling power connection.
A platform member generally designated 84 is suspended
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by four cables 86 from the carriage assembly 50, two of the
cables 86 extending from each carriage 50. As seen in
Figs. 9 and 10, within an upper housing 88 of the platform
member 84 are four motors 90. A lower part of each cable
86 enters the housing 88 through a respective opening 92 on
the upper surface of housing 88, and is wound around a
rotor spindle 94 on a respective one of the four motors 90.
The four motors 90 are actuated simultaneously to either
raise or lower the platform member 84. A helical power
line 96 extends between platform member 84 and one of the
carriages 50, and another connecting helical power line 98
extends between the carriage 50 and a ceiling power connec-
tion. This arrangement provides power to the motors 90 at
all lateral positions of carriage assembly 48 and all vert-
ical positions of the platform member 84.
Rotatably mounted under the housing 88 for rotationaround a vertical axis is a disk 100. A motor (not shown)
inside the housing 88 is adapted to rotate disk 100. Con-
nected to the disk 100, and extending downwardly from the
periphery thereof, is a strut 102. To a lower end of the
strut 102 a powered joint 104 is connected. A second strut
106 is connected to joint 104, and extends downwardly of
that joint to support a connected platform 108. A motor
(not shown) within the joint 104 is adapted to rotate
second strut 106 relative to strut 102, and thereby rotate
platform 108 relative to housing 88. The power to actuate
the motors which rotate the disk 100 and the platform 108
is provided through the helical power lines 96 and 98.
As shown in Figures 1 and 2, the platform 108 may be
used to support a camera generally designated as 110 in a
studio. With respect to the studio configuration in Figure
2, the integrated control system of Figure 12 is used to
control five degrees of motion for each of three support
platforms 114, 116 and 118. One person controls the X, Y
and Z directional degrees of motion for each of the three
platforms 114, 116 and 118 using monitor 120 and joystick
122, while a second person controls the two rotational
degrees of motion for each of the platforms using monitor
A
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124 and joystick 126.
Where no vertical members exist for supporting the
aerial support platform of the invention, a rigid truss is
used. Depending on its size, a truss may be hoisted by a
single crane, or by a crane positioned on each side, or by
a crane positioned at each corner. In Figure 13, a pair of
cranes 128 and 129 each connects to a respective opposite
side of a truss 130. The truss 130 supports two cables 132
and 134 in a manner similar to that in which the cables 14
and 16 are supported in Figure 1. Three carriages 136 ride
on cable 132, and three carriages 138 ride on cable 134. A
transverse cable 140 connects each carriage 136 with a res-
pective carriage 138, and on each cable 140 sits a carriage
142. This configuration differs from the Figure 2 embodi-
ment in that movement of the three aerial support platformsis dependent on each other. In Figure 2, there is a suffi-
cient vertical distance between each of the three support
cables 150, 152 and 154 on each side wall that each of the
associated support platforms is movable to any position in
the studio.
