Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STABILIZED THREE-AXIS CAMERA HEAD
BACKGROUND OF THE INVENTION
[0001] The field of the invention is remote camera heads and stabilized
platforms and systems for cameras. In motion picture, television, or video
filming or recording, the camera is often supported on a vehicle, to follow an
action or moving sequence, to achieve a desired camera angle or effect, or to
film occupants in or on a vehicle. Various specialized camera cranes, dollys,
and other mobile platforms have been used for this purpose.
[0002] Over the last several years, remote camera heads have
increasingly been used. A remote camera head is an apparatus that allows
the camera to be moved, aimed, or controlled from a remote location (i.e., a
location not immediately behind the camera). Typically, a remote camera
head is mounted on a crane arm. The crane arm can move the camera head,
and the camera on the head, into locations not accessible using conventional
camera operations (i.e., with a camera operator behind the camera and
controlling camera movement by hand). For example, a camera on a camera
head may be suspended on a crane arm extending out over the side of a tall
building, a cliff, a waterfall, etc., i.e., in a position where it would be
unsafe,
impractical, or impossible to perform conventional camera operations.
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[0003] In general, remote camera head operations involve placing the
camera on a remote camera head which can perform pivoting or rotational
movement in three axes, known as pan, tilt, and roll or dutch. Electric motors
on or in the remote camera head are remotely controlled (via cables or
wireless links) by a camera head operator, typically on the ground, or on the
vehicle supporting the crane arm. Operation of the camera itself is similarly
remotely controlled.
[0004] While camera heads have been successfully used in the past,
several disadvantages remain. As camera heads generally have various
electrical and electronic components (motors, sensors, etc.), they are
typically
limited to use only in clean and dry conditions. Adverse environmental
conditions, such as rain, snow, dust, sand, etc., can often cause degraded
performance or failures with camera heads. Accordingly, there is a need for a
rugged camera head providing reliable performance in all weather conditions.
[0005] Many camera heads are relatively difficult and time consuming to
set up, balance, operate, or reconfigure. Since production time can be
extremely expensive, even short delays associated with use of a camera head
can be disadvantageous. Consequently, there is a need for a camera head
which can be quickly and easily transported, installed, and made ready for
use.
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[0006] Many camera heads are set up for remote control using motors
which drive or move components of the camera head. However, to preview
lens angles, or for other reasons, a camera operator may want to manually
position the camera. This typically requires that the motors be disconnected
or
disengaged, to allow the camera head to be easily moved by hand.
Unfortunately, with many camera heads, this disengagement for hand
movement, can be time consuming and difficult. Similarly, re-engaging or
reconnecting the motors for electrical movement of the camera head, can also
be time consuming.
[0007] In filming or recording with motion picture or television or video
cameras, it is important for the camera to be maintained in a stable position.
In the most basic form, camera stability has been achieved by mounting the
camera on a tri-pod. However, when the camera itself is mounted on and
moves with a vehicle, maintaining camera stability often becomes difficult.
For
example, with a camera mounted on a camera car moving along a roadway
and filming a fixed subject on the ground or another moving vehicle, the
camera and the lens of the camera will necessarily move in unintended and
undesirable ways, due to various factors. These factors may include changes
in the roadway direction or inclination, changes in the vehicle orientation,
due
to shifting gravitational or inertial loads, as well as for other reasons.
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Undesirable movement can be especially problematic when the camera is
mounted on an aircraft, where movement readily occurs along three
dimensions, and where wind buffeting of the camera can be extreme. The
undesirable camera lens movement resulting from these factors reduces the
quality of the filmed or recorded images, by causing the images to be
improperly framed, or to appear jumpy or erratic.
[0008] To maintain the camera lens in a stable position in these types of
situations, various camera stabilization systems have been proposed.
Generally, these camera stabilization systems rely on gyrostabilization and
feedback techniques which detect unintended or undesirable movement of the
camera, and then compensate for that movement via motors driving the
camera platform. The term gyrostabilization here means any camera
movement compensation system using position, rate, or acceleration sensors,
whether "gyroscopic" or of another type.
[0009] While these types of stabilization systems have been successfully
used in the past, various disadvantages remain. The gimbal system used in
existing stabilized camera systems, which allows the camera to pivot about
three perpendicular directions, are often large and relatively time consuming
or
difficult to balance. This can restrict camera movement and positioning and
also make transport, installation and set-up (including balancing) more
difficult.
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Moreover, existing systems generally have large moments of inertia, making
them relatively slower in responding to correction forces applied by the
motors.
Accordingly, there is a need for a camera stabilization system which is
compact, lightweight, and agile in responding to correction signals and
forces.
[0010] The camera operator, cinematographer, or director will often want
to manually aim the camera, by simply grabbing the camera with the hands,
and aiming it as desired. Existing camera stabilization systems, when turned
on, will automatically resist such manual movement. While this resistance can
be overcome by applying force sufficient to overcome the torque limits of the
motors in the stabilization system, this results in jerky and imprecise camera
movement. As a result, manually aiming or positioning of the camera by
forcibly overriding stabilization system has disadvantages, and generally is
almost never acceptable during filming.
[0011] On the other hand, turning the stabilization system off to perform
hand or manual camera aiming or movement results in loss of all stabilization
functions. With the stabilization turned off, the only forces holding the
camera
in position are the frictional forces in the various rotation joints. Based on
the
weight of the camera and other factors, these frictional forces may be
insufficient to even hold the camera at any desired position. In' addition,
due to
static and dynamic friction characteristics, achieving smooth and accurate
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camera movement, even with the stabilization system turned off, can be
difficult or impossible. Accordingly, there is a need for a camera
stabilization
system which allows for smooth and accurate manual aiming.
[0012] Over longer periods of time, drift in existing camera stabilization
systems can cause the camera to become improperly positioned. The severity
of drift varies with the accuracy of the sensors in the system. Due to drift,
under certain conditions, the camera may require repositioning before filming
or recording is continued after a lunch break or other pause. This can result
in
delays and added production costs. Accordingly, there is a need for a camera
stabilization system which compensates for or eliminates drift.
[0013] Existing camera stabilization systems have various other
disadvantages as well, relating to backlash in the drive systems, balancing,
large moments of inertia, controls and accuracy of positioning.
[0014] Accordingly, various engineering challenges remain in designing
an improved camera head and an improved camera stabilization system.
STATEMENT OF THE INVENTION
[0015] After extensive research and ' development, the various
engineering challenges described above associated with camera heads and
stabilized camera systems have now been overcome in new systems
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providing significantly improved performance and advantages. These
advantages include all weather operation, submerged operation, rapid set-up
and adjustment, wide ranging adaptability for handling cameras of various
shapes, sizes, and weight, compact design, precise positioning, and improved
performance features and characteristics.
[0016] In a first aspect, a camera support or camera head has a pan
frame, a tilt frame securable onto the pan frame at multiple positions on the
pan frame, and a tilt frame securable onto the pan frame at multiple positions
on the pan frame. A quick release lever is advantageously used to secure the
frames at desired positions, to configure the camera head as desired.
[0017] In a second aspect the pan frame includes a pan housing, a pan
arm rotatably attached to the pan housing and a pan motor for moving the pan
arm relative to the pan housing. The tilt frame includes a tilt housing, a
tilt arm
rotatably attached to the tilt housing and a tilt motor for moving the tilt
arm
relative to the tilt housing. The tilt frame is securable onto the pan arm at
multiple positions along the pan arm. In an additional aspect of the
invention,
a roll frame is also included, having a roll housing and a camera platform
rotatably attached to the roll housing, and a roll motor for moving the camera
platform relative to the roll housing. In this design, the roll frame is also
securable onto the tilt arm at multiple positions along the tilt arm. Since
the
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frames or arms can be quickly moved into a desired position, and then
securely locked into place, via a cam lever or other locking device, the
camera
head can be quickly and easily configured to carry a wide range of cameras
and/or related equipment.
[0018] In a third aspect of the invention, a camera head includes a slip
ring assembly for each axis of rotation, and with waterproof cable segments
extending between the slip ring assemblies. Electrical connections are made
water proof or resistant. Bearings within the camera head are sealed. This
allows the camera head to be used in the rain, or even underwater, without
loss of performance.
[0019] In a fourth aspect of the invention, a pan or first shaft is rotatably
supported within a pan or first housing. A tilt or second frame is attached to
the first shaft, and the first shaft is sealed against the first housing. A
first gear
is linked to the first shaft through a first clutch. The first gear is linked
to the
first motor. At least one clutch operation lever on the housing is moveable
from a first position, wherein the lever engages the first clutch to allow the
first
motor to drive the first shaft, to a second position, wherein the lever
disengages the first clutch, allowing the first shaft to rotate free of the
motor.
This allows for quickly switching the camera head over between automatic
operation (via the motors), to manual operation (i.e., positioning the camera
by
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hand). In addition, since the motors are de-coupled during manual operation,
only low force is needed to move the frames. This makes precise camera
positioning easier and faster.
[0020] In a fifth aspect of the invention, a stabilized camera system
includes a roll or dutch frame pivotably attached to a pan frame. The roll or
dutch frame includes a parallelogram linkage. A tilt frame is pivotably
attached
to the parallelogram linkage of the roll frame. This results in a more compact
and lightweight design. With this design, the camera system can also be more
quickly and easily installed and balanced.
[0021] In a sixth aspect of the invention, a manual camera aiming mode
provides electronically controllable fluid dampening head characteristics. Via
electronic controls, the amount of dampening and inertia encountered during
manual movement or aiming of the camera can be adjusted. This allows for
smooth positioning or aiming of the camera by hand. It also allows the camera
to be supported with fluid head-like characteristics.
[0022] In a seventh aspect of the invention, a camera stabilization
system uses feedback from a position sensor on the camera platform to
reduce or eliminate drift. As a result, even using sensors of moderate
accuracy, drift can be virtually eliminated or reduced to acceptable levels.
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[0023] In an eighth aspect of the invention, a dutch or roll axis control
circuit
provides a fast to horizon control mode, for rapidly moving the camera
platform to
horizontal. This feature allows the camera operator to rapidly confirm that
the
camera is level relative to the horizon or the "local horizon".
[0024] In a ninth aspect of the invention, first and second electric motors
drive movement of pan, roll, and tilt frames or structures. This feature
reduces
backlash providing greater accuracy in control and positioning.
In another aspect of the invention, there is a camera head
comprising: a first frame; a first arm rotatably attached to the first frame;
a first
motor for rotating the first arm relative to the first frame, with the first
motor
enclosed within a sealed first housing; a second frame attached to the first
arm; a
second arm rotatably attached to the second frame; a second motor for rotating
the second arm relative to the second frame, with the second motor enclosed
within a sealed second housing; a first shaft rotatably supported within the
first
housing, with the second frame attached to the first shaft, and the first
shaft
sealed against the first housing, a first gear linked to the first shaft
through a first
clutch, and with the first gear linked to the first motor, and one or more
clutch drive
pins sealed against the first housing, and moveable from a first position,
wherein
the first motor drives the first shaft through the first clutch, to a second
position,
wherein the first shaft can rotate free of the motor.
In a further aspect of the invention, there is a remote camera head
comprising: a first frame; a first sealed housing on the first frame; a first
arm
rotatably attached to the first frame; a first motor for rotating the first
arm relative
to the first frame, with the first motor enclosed within the first sealed
housing; a
second frame attached to the first arm; a second sealed housing on the second
frame; a second arm rotatably attached to the second frame; a second motor for
rotating the second arm relative to the second frame, with the second motor
enclosed within the second sealed housing; a first hollow shaft rotatably
supported
within the first sealed housing, with the second frame attached to the first
shaft,
and the first shaft sealed against the first sealed housing; a first gear
linked to the
first shaft through a first clutch, and with the first gear linked to the
first motor; a
first slip ring assembly extending into the first hollow shaft; a first shaft
plug within
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and sealed against the first hollow shaft; a first electrical cable extending
into a
first end of the first slip ring assembly via a waterproof connection; and a
second
electrical cable extending through a waterproof connection in the first shaft
plug
and into a second end of the first slip ring assembly.
In a still further aspect of the invention, there is a camera support
comprising: a first housing having a first interior sealed space; a first
purge gas
port on the first housing connecting into the first interior sealed space, for
delivering a purge gas into the first interior sealed space; a first motor
supported
by the first housing; a second housing having a second interior sealed space,
and
with the second housing linked to the first motor for rotational movement of
the
second housing relative to the first housing about a first axis; a second
motor
supported by the second housing; a second purge gas port on the second housing
connecting into the second interior sealed space, for delivering a purge gas
into
the second interior sealed space; a third housing linked to the second motor
for
rotational movement of the third housing relative to the second housing about
a
second axis substantially perpendicular to the first axis; and a lock pin
moveable
between a lock position, where the lock pin extends between the first housing
and
the second housing, to prevent movement between them, and an unlock position,
wherein the lock pin is withdrawn from one of the first and second housings,
to
allow rotational movement between them.
In yet another aspect of the invention, there is a camera support
comprising: a first housing having a first interior sealed space; a first
purge gas
port on the first housing connecting into the first interior sealed space, for
delivering a purge gas into the first interior sealed space; a first motor
supported
by the first housing; a second housing having a second interior sealed space,
and
with the second housing linked to the first motor for rotational movement of
the
second housing relative to the first housing about a first axis; a second
motor
supported by the second housing; a second purge gas port on the second housing
connecting into the second interior sealed space, for delivering a purge gas
into
the second interior sealed space; a third housing linked to the second motor
for
rotational movement of the third housing relative to the second housing about
a
second axis substantially perpendicular to the first axis; a first shaft
rotatably
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supported within the first housing, with the second housing attached to the
first
shaft, and the first shaft sealed against the first housing, a first gear
linked to the
first shaft through a first clutch, and with the first gear linked to the
first motor, and
one or more clutch drive pins sealed against the first housing, and moveable
from
a first position, wherein with first motor drives the first shaft through the
first clutch,
to a second position, wherein the first shaft can rotate free of the motor.
[0025] The invention resides as well in subcombinations and subsystems of
the components, elements, and steps described. Each of the aspects described
above may be used alone, or in combination with one or more of the other
aspects. The essential elements are described in the claims, with no one of
the
aspects above essential to all embodiments of the invention.
BREIF DESCRIPTION OF THE DRAWINGS
[0026] In the drawings, wherein the same element number generally
indicates the same element in each of the views:
[0027] Fig. 1 is a perspective view of the present camera head in use,
mounted on a telescoping crane arm.
[0028] Fig. 2 is a perspective view of the camera head shown in Fig. 1, in
an upright position.
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[0029] Fig. 3 is a perspective view of the camera head shown in Fig. 2,
with the camera platform inverted.
[0030] Fig. 4 is a side view, in part section, of the camera head shown in
Figs. 2 and 3, with the camera and electrical components omitted for clarity
of
illustration.
[0031] Fig. 5 is an enlarged detail view, in part section, of the pan frame
shown in Fig. 4.
[0032] Fig. 6 is an enlarged detail view, in part section, of the tilt frame
shown in Fig. 4.
[0033] Fig. 7 is an enlarged detail view, in part section, of the roll frame
shown in Fig. 4.
[0034] Fig. 8 is a section view taken along line 8-8 of Fig. 4.
[0035] Fig. 9 is a bottom view taken along line 9-9 of Fig. 4.
[0036] Fig. 10 is a side elevation view, in part section, of the camera
head shown in Fig. 4.
[0037] Fig. 11 is an enlarged detail view, in part section, of the pan
housing shown in Fig. 10.
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[0038] Fig. 12 is an enlarged detail view, in part section, of the roll
housing shown in Fig. 10.
[0039] Fig. 13 is an enlarged detail view, in part section, of the tilt
housing shown in Fig. 10:
[0040] Fig. 14 is a front elevation view of the camera platform, taken
along line 14-14 of Fig. 10.
[0041] Fig. 15 is a plan view of the camera head shown in Figs. 4
and 10.
[0042] Fig. 16 is a side elevation view of the tilt frame, taken along line
16-16 of Fig. 15.
[0043] Fig. 17 is an enlarged detail view, in part section, of components
of the tilt frame and roll frame shown in Fig. 15.
[0044] Fig. 18 is a side view showing the tilt frame in a first or retracted
position on the pan frame.
[0045] Fig. 19 is a side view thereof, showing the tilt frame in a second or
extended position on the pan frame.
[0046] Fig. 20 is an enlarged section view of the roll housing shown in
Figs. 7, 10, and 12.
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[0047] Fig. 21 is a further enlarged section view thereof.
[0048] Fig. 22 is an enlarged view of the pan axis stop pin shown in
Fig. 2.
[0049] Fig. 23 is an enlarged view, in part section, of the connector pairs,
shown in Figs. 1 and 10.
[0050] Fig. 24 is a side view of a remote camera head and camera
stabilization system mounted on a camera crane having a fixed length boom
arm.
[0051] Fig. 25 is a front and left side perspective view of the camera
system shown in Fig. 24.
[0052] Fig. 26 is a front and right side perspective view thereof.
[0053] Fig. 27 is a plan view of the camera system shown in Figs. 25 and
26.
[0054] Fig. 28 is a left side elevation view thereof.
[0055] Fig. 29 is a front view thereof.
[0056] Fig. 30 is a schematically illustrated side view of the present
camera support system showing alternative positions.
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[0057] Fig. 31 is a front view thereof with the camera removed, for
purpose of illustration.
[0058] Fig. 32 is a schematic illustration of an automatic leveling system.
[0059] Fig. 33 is a schematic illustration of a drift compensation system.
[0060] Fig. 34 is a schematic illustration of a control signal distribution
system.
[0061] Fig. 35 is a schematic illustration of a camera stabilization system
including a manual camera aiming mode function.
[0062] Fig. 36 is a schematic illustration of the manual camera aiming
mode circuit used in Fig. 35.
[0063] Fig. 37 is a plan view of a control panel for use with the system
shown in Fig. 35.
[0064] Fig. 38 is a perspective view of a motor assembly as used on the
system shown in Figs. 25-31.
DETAILED DESCRIPTION OF THE DRAWINGS
[0065] Turning now in detail to the drawings, as shown in Fig. 1, the
camera head 50 of the invention is supported on the nose or front end 42 of a
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crane arm 40. The crane arm 40 is supported on an arm or post 32 of a
mobile dolly 30. The dolly 30 is typically on wheels 34, so that it can easily
be
maneuvered and steered. Counterweights 44 are typically provided at the
back end of the crane arm 40, for balancing.
[0066] In Fig. 1, a motion picture or video camera 60 is attached onto the
head 50. The front end or nose 42 of the crane arm 40, the head 50, and the
camera 60 are submerged in a pool or tank of water 54, to film an action
sequence of a diver 52. Of course, Fig. 1 shows but a single example of use
of the camera head 50. In practice, the camera head 50 can be mounted on
various motorized camera cranes, carts, dollys or other mobile bases, to
position and maneuver a camera 60 at elevated positions, near ground level
positions, below ground level positions, within interior spaces of buildings
or
enclosures, etc. Indeed, the camera head 50 maybe used in any application
where remote positioning and maneuvering of a camera 60 is desired.
CAMERA HEAD DESIGN
[0067] In Figs. 2 and 3, the camera head 50 is shown supported on a
track 41 of an alternative camera crane or dolly. The camera head 50
comprises three principle assemblies or units, specifically a pan frame or
assembly generally indicated at 70, a tilt frame or assembly generally
indicated
at 72, and a roll or dutch frame or assembly generally indicated at 74. The
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pan frame 70 is supported on a crane arm 40, track 41 or similar support and
provides pivoting or rotational movement about a pan-axis P, typically a
vertical upright axis. This allows the camera 60 to be moved with a panning or
clockwise/counterclockwise sweeping horizontal movement. The tilt frame 72
supported on the pan frame 70 provides for pivoting or rotational movement
about a tilt axis T, to change the elevation angle of the camera 60. The roll
frame 74 which is supported on the tilt frame 72 provides for pivoting or
rotational movement about a roll axis R. In contrast to Fig. 2, Fig. 3 shows
the
camera platform inverted, at a near 180 roll or "dutch angle. Since the
camera head 50 allows the camera 60 to be pivoted or rotated about each of
the three axes, the lens of the camera 60 can be moved into any desired
angular position.
[0068] Referring to Figs. 4, 5, and 11, the pan frame 70 includes a pan
housing 80 containing or supporting a pan motor 86. As shown in Fig. 11, a
pan shaft 82 is joined to a top plate ring 83 which rotates relative to
housing
80.. A pan gear 84 is attached to the shaft 82 through a clutch assembly 102
providing overload protection and allowing disengagement for quick and easy
manual operation. The electric pan motor 86 drives a worm gear 110 which
meshes with the pan gear 84. A pan axis slip ring assembly 88 is supported
on or in the pan housing 80, to provide electrical connections through the
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rotating joint. A locking nut 85 around the top end of the pan housing 80 is
used to attach the camera head 50 to a crane arm or other support.
[0069] Referring to Figs. 3-5 and 22, a pan arm 96 is rotatably attached
to the pan housing 80 via a sealed bearing 92. The pan arm 96 rotatably seals
against the pan housing 80 via an O-ring seal 94. Referring to Fig. 11, when
electrical power is applied to the pan motor 86, the worm gear 110 drives the
pan gear 84 through the clutch 102 causing the pan shaft 82 to rotate. As the
pan arm 96 is rigidly attached to the pan shaft 82, the pan arm 96 therefore
rotates, while the pan housing 80 remains fixed in place. To prevent
inadvertent relative movement of the pan arm 96, a spring biased pan axis
stop pin 90 on the pan housing 80 can be engaged into an opening or hole 91
in the pan arm 96, as shown in Figs. 2 and 22, locking them together against
rotation.
[0070] Referring momentarily to Fig. 9, which is a bottom view looking up
of the pan housing 80, a pair of cam engagement levers 98 lock the pan arm
96 into engagement with the pan shaft 82. For manual movement of the pan
arm 96, independent of, or without use of the motor 86, the cam levers 98 are
flipped over or released. This allows the pan arm 96 to rotate freely, for
hand
or manual positioning or movement.
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[0071] Figs. 20 and 21 show operation of the cam levers 98. A cam
surface on each cam lever 98 rests against a clutch drive pin 99, which
contacts the first or outer clutch plate 185 of the roll clutch 184. With the
levers in an engaged position, the cam levers drive the clutch drive pins 99
hard against the clutch plate 185. This engages the clutch, causing the shaft
162 to rotate when the roll motor 166 is turned on. The cam levers and clutch
drive pins are dimensioned to limit the maximum applied torque of the clutch
to
a preset limit. With the cam levers 98 flipped over (about 180 degrees), the
clutch drive pins 99 are released, and the clutch is disengaged. The shaft
162,
and the entire camera platform supported on the shaft 162, can then be freely
rotated by hand, with minimum force. Q-rings 101 on the clutch drive pins 99
seal the pins against the housing 80, while still allowing the pins to move
axially.
[0072] As shown in Fig. 9, a drag lever 100 acts on a drag collar 120
around the base or bottom of the pan housing 80. A Teflon (Fluorine resins)
ring 122 is positioned between the drag collar 120 and the pan shaft 82.
Adjustment of the drag lever 100 increases or decreases friction on the pan
arm 96. The drag lever 100 has a cam surface including flat segments to
allow for incremental adjustment of drag. Similar drag adjustment is provided
for the tilt and roll frames.
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[0073] Referring to Figs. 4 and 6, the tilt frame 72 includes a tube angle
152 attached to a connecting tube 144 by an assembly bolt 142. The
assembly bolt 142 engages into a bolt plate 146 within the connecting tube
144, holding the tube angle 152 at an angle (preferably about 35 ) to the axis
of the connecting tube 144. Of course, these components may also be
perpendicular, or at other angles as well. Alignment pins 145 extend from the
connecting tube 144 into the tube angle 152, to help rigidly attach them
together, as shown in Fig. 6.
[0074] Referring still to Fig. 6, a tilt axis housing 130 is attached to the
connecting tube 144 at the (lower or bottom) end opposite from the tube angle
152. The tilt axis housing 130 includes components analogous to those on or
in the pan axis P housing 80 as described above. Specifically, an electric
tilt
motor 136 on or in the tilt housing 130 has a motor shaft with a worm gear 110
meshed with a tilt axis drive gear 134. The tilt drive gear 134 is linked to a
tilt
axis shaft 132 through a clutch 102. A tilt arm assembly 153 is rigidly
connected to the tilt axis shaft 132. A tilt axis slip ring assembly 138, and
a tilt
axis stop pin 140 are provided on or in the tilt axis T housing 130. The tilt
axis
stop pin 140 is similar to the pan axis stop pin 90 shown in Fig. 22, except
that
it is extendible into holes in a disk 133 joined to the tilt shaft 132.
Referring
momentarily to Fig. 10, cam release levers 98, and a drag/lock lever 100 and
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collar 120 are also provided on the tilt housing 130, similar to the pan
housing
described above.
[0075] Turning to Fig. 8, the tube angle 152 of the tilt frame 72 is
preferably a generally U or C-shaped channel section. The pan arm 96
extends into the tube angle 152. Rollers 222 supported on bearings 224 in the
tube angle 152 allow the tube angle 152 and the entire tilt frame 72, to move
in
or out along the pan arm 96, when the cam lock 220 is released. The rollers
222 roll and/or slide within a dovetail or undercut groove in the pan arm 96.
This allows the head 50 to be moved into the alternative positions shown in
Figs. 18 and 19. As a result, the head 50 can be expanded or contracted as
desired. For example, when a small size camera 60 is used, the head 50 can
be positioned as shown in Fig. 18, providing a compact design, yet with
adequate clearance for the camera 60, as well as any lenses, film magazines,
batteries, or other accessories provided with the camera 60.
[0076] On the other hand, for handling large cameras, the head 50 can
be expanded, as shown in Fig. 19, to provide adequate space for mounting the
camera and camera accessories. Referring to Fig. 8, when the tilt frame 72 is
positioned as desired on the pan arm 96, the cam lock 220 is closed by
pushing the cam lever down. This creates a large clamping force which locks
the tilt frame 72 into position. Teflon (fluorine containing resins) tape is
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advantageously placed on the bottoms and sides of the pan arm 96 and the tilt
frame tube extension 158, to allow for easy sliding movement when the cam
lock 220 is released. When the cam lock 220 is released or opened, a gap of
about 0.2 or 0.3 mm opens between the pan arm 96 and the tube angle 152.
The rollers 222 are then released and are free to roll, as they are no longer
clamped down by the compression of the pan arm 96 against the tube angle
154 by the cam lever 220. The load or weight of the tilt frame is then carried
by the rollers 222. This allows for fast and accurate low friction sliding
movement of the tube angle 152, to obtain the desired size of the camera
head. The cam lever 220 is then returned to the down or locked position,
tightly clamping and locking the tube angle 152 and the pan arm together, in a
single hand motion.
[0077] Referring to Figs. 3 and 15, the tilt arm assembly 153 includes a
tilt frame tube 154, preferably oriented perpendicular to the tilt shaft 132.
A tilt
frame extension section 158 is joined to the tilt frame tube 154 through an
angle section 156, and is preferably generally parallel to the tilt shaft 132,
and
perpendicular to the tilt frame tube 154.
[0078] Referring now to Figs. 4, 7, 10, 12, 15, and 17, the roll or dutch
frame 74 includes components similar to those described above relative to the
pan and roll frames. Specifically, a roll housing 160 has a motor 166 which
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drives a roll axis gear 164 through a worm gear 110 on the motor shaft. The
angle on the worm gear 110 is selected so that the worm gears 110 can be
back driven. This allows the pan, tilt, and roll frames to be manually
positioned, if needed, without releasing the cam locks 98 and offers added
resistance to movement when desired. The roll gear 164 drives a roll shaft
162 through a clutch 102. The clutches 102 preferably have a preset torque
limit. If the limit is exceeded, the clutch slips. This helps to protect the
motor,
gears, as well as camera equipment on the head 50. The torque limit is high
enough to allow the motors to rapidly move the pan, tilt, and roll frames.
However, the torque limit is also low enough to improve the safety of persons
working around the camera head, and to prevent damage to the camera head.
[0079] Referring to Figs. 7, 17, and 20, as with the pan and tilt housings,
the roll housing 160 also includes a slip ring assembly 168 and a stop pin
170,
which can be engaged or locked -in, to prevent any roll axis rotation.
Engagement cams 98 are provided to engage and disengage the clutch 102,
to disconnect the roll motor 166 from the roll shaft 162, e.g., for easy
movement of the camera by hand.
[0080] As shown in Fig. 7, a roll housing arm 180 is attached to the roll
housing 160 via alignment pins 176 and a connecting bolt 174. The roll
housing arm 180 is attached to the tube extension 158 of the tilt arm assembly
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153 via rollers and a cam lock 220, as shown in Fig. 8. This allows the roll
frame 74 to move in and out relative to the tilt frame 72, in the same way
that
the tilt frame 72 can be moved relative to the pan frame 70, as shown in Figs.
18 and 19.
[0081] Referring to Figs. 2, 10, 14, and 15, a camera platform 200 is
rigidly attached to the roll shaft 162. The camera platform 200 has a slotted
base plate 202 attached perpendicularly to a back plate 206. Gusset plates
210 are attached to the base plate 202 and back plate 206. The vertical
position of the camera platform 200 relative to the roll axis R can be
adjusted
by releasing cam levers 212 (shown in Fig. 14), vertically positioning the
camera platform 200, via sliding movement on rollers 205, and then locking
the cam levers 212. Hand bolts 214 extending up from the bottom side of the
camera platform 200 are used to attach the camera 60, or an adapter plate, to
the camera platform 200.
[0082] Referring back to Fig. 1, typically control, signal, power, and other
electrical wires or cables leading to-the camera 60 and camera accessories on
the head 50 extend back up on or through the crane arm 40, to the dolly,
mobile base, or other mobile support. These electrical lines allow the camera
operator to remotely operate the camera and to view (e.g., on a remote
monitor) the images recorded by the camera. The motors which control
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movement of the head, i.e., the pan motor 86, the tilt motor 136, and the roll
motor 166 also require electrical connections for power and control.
[0083] Generally, the pan, tilt and roll housings have similar or identical
components, and they operate the same way. Figs. 20 and 21 show enlarged
views of the roll housing 160. However, the details shown in Figs. 20 and 21
typically apply as well to the pan and tilt housings as well. To make the
camera head 50 waterproof or water resistant, the housing 160 is sealed. As
shown in Fig. 20, the roll shaft 162 is rotatably supported on a first or
outer
bearing 244 and a second or inner bearing 245. A shaft seal 246 seals
against the roll shaft 162 against the housing 80, while allowing the shaft
162
to rotate. A second or inner- shaft seal or O-ring 237 similarly seals the
shaft
162 against the inner end of the housing 80. A bearing seal or O-ring 238
seals off the inner end of the housing and the inner bearing 245.
[0084] Referring still to Figs. 20 and 21, a tube fitting or nipple 89 is
joined to or part of a plate 230. Screws passing through the plate, and the
outside of the slip ring assembly 168, attach them to the housing 80.. O-rings
234, 235, and 236 seal the plate 230 and the slip ring assembly 168 to the
housing. A plastic or rubber tube 243 is attached to the nipple. As shown in
Fig..1, a control and power cable 250 linked to the camera 60 extends from the
crane arm 40 to a tube fitting 89 on the pan housing, and from there to tube
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fittings 89 on the tilt and roll housings. The cable 250, or wires leading to
the
control cable, are contained within segments of the tube 243. The wires make
a rotatable connection in each slip ring assembly (with the roll axis slip
ring
assembly 168 shown in Figs. 20 and 21). The wires then extend through the
shaft 162 (or the shafts 82 or 132), through a shaft plug 240, and then out of
the housing 160 (or housing 80 or 130), within another section of the tube
243.
The shaft plug 240 is sealed against the shaft by O-rings 242. Consequently,
both the housing and the electrical connections are sealed.
[0085] To allow for quicker set up or configuration changeover, three
pairs of waterproof connectors are provided. A first pair of connectors 252 is
mounted on the pan frame 70, a second pair 254 is mounted on the tilt frame
72, and a third pair 256, as shown in Fig. 10, is mounted on the roll frame
74.
Routing the electrical lines through the connectors allows the frames to be
removed and replaced as desired, or conversion between two and three-axis
operation, without the need for separate handling of the electrical lines or
wires. As the slip ring assemblies, connectors, wiring, and motors are sealed,
the entire head 50 can be submerged, as shown in Fig. 1, without detrimental
loss of performance or reliability.
[0086] Referring to Fig. 23 which shows the details of the connector pairs
252, 254, and 256, a first end cover having a first hose adapter or fitting
282 is
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attached (via screws) to a female housing 270. A locking collar 274 captive on
the female housing 270 threads onto a male housing 286. A female half-
coupling 276, and male half-coupling 278, and a compactor allow the male and
female housings to be joined into a watertight connection.
[0087] A second end cover 284, having second and third hose fittings
280 and 283 is similarly attached to the end of the male housing 286. End
covers 290 and 284 are secured over and around the hose fittings. A bracket
288 attached to the male housing 278 allows the connector pair to be easily
attached to a flat surface on the pan, tilt, or roll frames. O-rings 292 and
296,
and a packing 298, seal the hose fittings 282, 283, and 280 to the male and
female housings 286 and 270. An O-ring 294 seals male half-coupling 278 to
the male housing 286. This design as shown in Fig. 23 provides a waterproof
connector pair, allowing for submerged operation of the camera head 50, and
also providing a quick disconnect feature for electrical lines or wires
running to
the camera and camera accessories on the head, and/or for the electrical
motors or other electrical components of the camera head itself.
[0088] Accordingly, new and dramatic camera movements, not
previously readily achievable, can now be performed. For example, using the
crane arm 40 and the head 50, the camera 60 can follow an action sequence
beginning on land, and then moving, without interruption, into an underwater
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environment, such as a swimming pool, lake, etc. In addition, the head 50 can
be used in wet or rainy environments, without taking protective steps, such as
draping or wrapping, since the head 50 is largely impervious to water.
[0089] As shown in Figs. 4, 8, and 17, the head 50 has various hollow
interior spaces. Each space is provided with purge gas ports 226.
[0090] By purging the interior spaces with dry nitrogen gas, the need for
painting, plating, or otherwise finishing the internal surfaces of the head 50
is
avoided, and internal corrosion is reduced or eliminated. As the head 50 is
modular and has no covers, it can be quickly and easily serviced.
[0091] As shown in Fig. 19, an extension or spacer 260 can be installed
in-between the pan frame 70 and tilt frame 72, or between the tilt frame 72
and
the roll frame 74, to expand or enlarge the camera head 50, for holding
unusually large or bulky cameras and/or camera accessories. A similar
extension may be installed to effectively lengthen the connecting tube 144 of
the tilt frame, shown in Fig. 6, or to lengthen the tube 154 or extension 158
of
the roll frame 74, shown in Figs. 3, 4, and 10.
[0092] While the drawings show a three-axis camera head, the same
designs described above may also be used in a two-axis camera head. In the
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two-axis design, the tilt arm assembly 153 is removed and the camera platform
200 is attached directly to the tilt shaft 132.
CAMERA HEAD SETUP
[0093] In use, the head 50 is mounted on a camera crane 40 or other
support such as a vehicle,, overhead cable trolley, etc. The overall size or
envelope of the camera head 50 is adjusted, as desired, to meet the clearance
space requirements of the camera and camera accessories by releasing the
cam locks 220, appropriately positioning the tilt frame 72 and the roll frame
74,
and then engaging or locking the cam locks 220. The camera is mounted onto
the camera platform 200. Appropriate electrical connections are made via the
connector pairs 252, 254, and 256 through the slip ring assemblies 88, 138,
and 168. The camera head 50 is then balanced, using known techniques. For
example, movement about the pan and tilt axes is locked out by engaging the
stop pins 90 and 140. The camera is then balanced about the roll axis R.
Next, rotational movement about the pan and roll axes is locked out via the
locking or stop pins 90 shown in Figs. 6, 11, and 22, and 170 shown in Figs. 4
and 7, while the camera head 50 is balanced about the tilt axis T. The camera
head 50 is then balanced about the pan axis P, in a similar way, via
preventing
rotational movement about the roll axis R and the tilt axis T, using the stop
pins 140 and 170.
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[0094] The camera head 50 provides several advantages. It can be
used underwater, or in wet environments, since all bearings, motors, and
electrical components and fittings are waterproof or sealed. Movement of the
camera head 50 in three axes can be remotely controlled via electrical signals
to the motors. Alternatively, the motors and gears can be quickly disengaged
from the frames via the cam levers 98, for manual or hand control or
positioning of camera movement about any of the pan, tilt, or roll axes. Even
without disengaging the motors, the frames can be forcibly moved manually,
as the gears 84, 134 and 164 can back drive the worm gear 110, before the
clutch 102 slips, if sufficient force is applied.
[0095] The camera head 50 is also compact and lightweight.
Accordingly, it can be used in confined spaces. It can also be mounted on
smaller and lower load carrying capacity crane arms. As a result, filming
shots
or sequences can be achieved with overall more compact, lightweight, and
more maneuverable and transportable equipment. The camera head 50 is
also highly reliable, as it has a simplified design (in contrast to other
camera
heads) and it is largely sealed against water, dust, dirt, etc. The camera
head
50 is also highly adaptable and can be set up to hold cameras and
accessories ranging from small compact digital video cameras, to large
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conventional film cameras, -along with associated lenses, film magazines,
batteries, and other camera accessories.
CAMERA HEAD STABILIZATION SYSTEM
[0096] As shown in Fig. 24, a camera 432 having a lens 434 is supported
on a camera stabilization system 430 at the front end of an arm 426 of a
camera crane 420. The camera crane arm 426 is pivotably supported on a
mast 424 on a mobile base 422. Fig. 24 accordingly shows one example of
the use of the camera stabilization system 430 with a camera 432. The
stabilization system 430 may also be used on various other types of platforms
or supports, including camera cars, camera trucks, camera dollys, aircraft,
watercraft, and virtually any other vehicle, base or support where
stabilization
is desirable.
GIMBAL DESIGN
[0097] Turning now to Figs. 25 and 26, the support system 430 includes
a pan frame 450 preferably formed as a hollow arcuate or curved box section.
A pan shaft 452 is rigidly attached (e.g., welded, bolted or pinned) to a
front
support plate 428 of the camera crane 420 or other support vehicle or
structure. The pan frame 450 can pivot or rotate on the pan shaft 452 about a
pan axis 451, as shown in Fig. 25.
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[0098] Referring still to Figs. 25 and 26, a dutch or roll frame 454 is
attached to a roll collar 490 having a roll shaft 456 extending into the lower
end
of the pan frame 450. The roll frame 454 is pivotable or rotatable about a
roll
axis 455 shown in Fig. 26. The roll frame 454 preferably includes a
parallelogram linkage 488 having first and second parallel links 492 and 494.
The back ends of the links 492 and 494 are attached to the roll collar 490
with
locking bolts 486. Similarly, the front ends of the roll links 492 and 494 are
attached to a tilt collar 500 with locking bolts 486. The locking bolts 486
are
loosened during balancing or set-up, to properly position the roll frame 454.
The locking bolts 486 are then tightened, at four places, to provide a rigid
connection between the roll collar 490 and the tilt collar 500. The roll frame
454 requires no other internal or external components, such as springs,
dampeners, etc.
[0099] Referring still to Figs. 25 and 26, a tilt frame 458 has a tilt shaft
460 extending into the tilt collar 500. The tilt frame 458 is pivotable about
a tilt
axis 459, shown in Fig. 25. Referring to Fig. 25 and momentarily to Fig. 31,
the tilt frame 458 includes an L-shaped camera platform 462. The camera 432
is secured onto the platform 462 via standard screws or bolts. The vertical
leg
of the camera platform 462, as shown in Fig. 31, extends through a sleeve 464
joined to the tilt collar 500. The vertical position of the camera platform
462
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(and of the camera 432) can be adjusted by loosening sleeve bolts 466,
vertically positioning the camera platform 462 as desired and then tightening
the sleeve bolts 466.
[00100] Referring now in addition to Figs. 27, 28, and 29, a pair of drive
motor assemblies 472, 474 is provided to drive the pan frame 450, the roll
frame 454, and the tilt frame 458. While the six drive motor assemblies used
in the system 430 are preferably the same, to provide a more clear
description,
each of the motors is separately referred to and numbered based on its
location and function in the system 430. Referring momentarily to Fig. 38, a
drive motor assembly 475 includes an electric motor 476 which drives an
output gear 479 through a speed reducing gear train 478.
[00101] Referring to Figs. 25, 26, and especially Fig. 29, the pan shaft 452
is preferably fixed in place (e.g., bolted, welded, etc.) on the support plate
428
and does not pivot or rotate. A pan shaft gear 470 is rigidly attached to or
part
of the pan shaft 452. The pan shaft gear 470 is preferably located within the
pan frame 450, although it may also be external. The pan frame 450 is
rotatably supported on the pan shaft 452 via bearings. First and second pan
motor assemblies 472 and 474 are attached to the outside of the pan frame
450. The output gear 479 of each of the pan motor assemblies 472 and 474
engages or meshes with the pan shaft gear 470. Consequently, the electric
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motors 476 of the pan motor assemblies 472 and 474 are positioned to exert
torque on the pan frame about the pan axis 451.
[00102] A similar design is provided for rotation about the dutch or roll axis
455 and the tilt axis 459. As shown in Figs. 26 and 28, the dutch or roll
shaft
456 is rotatably supported via bearings to the lower end of the pan frame 450.
A roll shaft gear 480 is fixed to the pan frame 450. First and second roll
axis
motors 482 and 484 are attached to the outside of the roll collar 490. The
output gear 479 of each of the roll axis motors 482 and 484 is engaged with
the roll shaft gear 480. Consequently, the roll axis motors 482 and 484 are
positioned to exert torque on the dutch or roll frame 454 about the dutch or
roll
axis 455.
[00103] In a similar way, as shown in Fig. 29, the tilt axis shaft 460 is
rotatably supported on bearings in the tilt collar 500 at the front end of the
roll
frame 454. A tilt shaft gear 502 is irrotatably attached to the tilt collar
500.
First and second tilt motor assemblies 504 and 506 are attached to the outside
of the tilt collar 500. The output gear 479 of each tilt motor 504 and 506
meshes with the tilt shaft gear 502. Consequently, the tilt motors 504 and 506
are positioned to exert torque on the tilt frame 458 about the tilt axis 459.
Each of the motor assemblies described 472, 474, 482, 484, 504, and 506 is
preferably the same as the motor assembly 475 shown in Fig. 38. The
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positions of the motor assemblies and gears, whether inside or outside of the
frames, is immaterial to the invention and may be selected based on design
choice.
[00104] Referring to Fig. 26, by locating the dutch or roll axis motors 482
and 484 on the dutch collar 490, the stabilization system 430 is made more
compact and lightweight. As the weight of the system 430 is reduced, it has
less inertia. This reduced inertia reduces the torque requirements of the
stabilization system. Consequently, the system 430 can have smaller motors,
use less electrical power, have less friction, and provide more accurate
stabilization. In addition, the placement of the motors 472, 474, 482, 484,
504,
and 506 close to the axis of rotation 451, 455, and 459 reduces the angular
moment of inertia of the pan frame 450, dutch or roll frame 454, and tilt
frame
458, also providing for rapid stabilizing movements.
[00105] Preferably, the motor assemblies are powered and controlled by
cables or wires extending back from the stabilization system 430 to an
electronics box 442 containing circuitry and a power supply. A control panel
or
box 440 is connected to the electronics box 442 preferably via cables.
Alternatively, wireless connections may be used. If desired, slip rings and/or
slip-type electrical connectors or fittings can be used to minimize wind-up of
the cables.
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[00106] As shown in Figs. 27, 28, and 29, to prevent excessive wind-up of
the cables, a stopping or limiting mechanism 512 is provided within the system
430 about each of the axis. Typically, the limiting mechanism 512 will allow
e.g., only two or three complete 3600 revolutions. The limiting device 512
typically includes several interlocking rings, as is well known in the art. A
locking device 514 is also provided for each axis. The locking mechanism 514
is used during storage, shipment, set-up or calibration and locks each of the
frames into a zero (or other preset) angle position. The locking mechanisms
514 are generally disengaged when the system 430 is in use.
[00107] Figs. 24-31 show the mechanical design of the system 430
providing various advantages. Figs. 32-37 show electronic and control
designs. While these designs are preferably used in the system 430 shown in
Figs. 24-31, they can also be used in many other types of camera stabilization
systems. Conversely, the system 430 shown in Figs. 24-31 may be used with
any of the circuits, features, or control modes shown in Figs. 32-36, or it
may
be used with existing control systems.
MANUAL AIMING SYSTEM
[00108] Referring to Fig. 35, a camera stabilization system or subsystem
530 includes a manual aiming mode. An adder, mixer, or summator 522,
manual control circuit 532, amplifier 524, and sensor 526 is provided in each
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separate circuit 550, 552 and 554 for control of movement about each of the
pan, roll, and tilt axis 451, 455, and 459. The sensor 526 is preferably a
rate
sensor. Referring to Fig. 35, .a separate input control device 520 associated
with each of the pan, roll, and tilt axis circuits 550, 552, and 554, provides
an
input signal to the summator 522. The input control device 520 may be a
joystick, control wheel, pedal, mouse, etc.
[00109] Referring to Fig. 36, the manual aiming circuit 532 is shown within
the dotted lines. For the control circuit 550, 552, and 554 associated with
movement about each axis 451, 455, and 459, a switch 534 has on and off
positions. In the off position, shown in dotted lines in Fig. 36, the manual
aiming circuit 532 is disconnected or inactive, and each of the circuits 550,
552, and 554 operates using traditional feedback control. With the switch 534
in the on position, as shown in solid lines in Fig. 36, the manual aiming
circuits
532 are active. Each' of the manual aiming circuits 532 includes a variable
resistor 538 forming a divider 536. A capacitor 542 in combination with a
second variable resistor 544 forms a differentiator 540. The outputs from the
divider 536 and differentiator 540 are added in a manual aiming summator
546. The output from the summator 546 is provided to the amplifier 524. The
design of the manual aiming circuit 532 in each of the three axis circuits
550,
552, and 554, are preferably the same.
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[00110] In use, the switch 534 is switched to the on position, shown in Fig.
36, when the camera operator wants to manually aim the camera 432. This is
a common event in film and video production. The camera operator will often
want to manually aim the camera (by grabbing and moving the camera
platform or the camera itself), for various reasons, such as checking or
monitoring a camera angle, field of view, etc. Traditional camera
stabilization
systems act to resist this type of manual movement, because such intended
movement via the hands of the camera operator are indistinguishable from
unintended camera movement caused by inertial or gravitational forces
associated with movement of the camera crane, motion base, or vehicle
supporting the camera, wind loads, etc. With existing systems, when the
manual aiming force applied by the camera operators hands exceeds the
maximum torque output of the motors, the camera platform suddenly breaks
free and can be manually aimed.
[00111] This results in an abrupt jerky movement which often overshoots
the desired position, with additional time consumed in achieving the desired
camera position. Alternatively, the stabilization system can be switched off
entirely before manual aiming. However, in either case, smooth camera
movement, in a manual mode, is difficult or impossible to achieve. Existing
camera stabilization systems either interfere with manual aiming, by
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automatically resisting such movements until torque' limits are exceeded, or,
when they are switched off entirely, provide no beneficial control
characteristics, with the camera platform moving entirely in response to
whatever forces (inertial, gravitational, wind, hand, etc.) may be
instantaneously acting on the camera platform. These effects result from the
fundamental basic conflicting objectives between a camera stabilization
system, which attempts to keep the camera lens aimed at a desired position,
regardless of external influences, and manual aiming where the camera
operator wants to simply aim the camera manually without interference.
[00112] Referring to Figs. 35, 36, and 37, the divider 536 provides
adjustable dampening, and the differentiator 540 provides an adjustable
inertia
feel, to manual camera aiming movement. Accordingly, the manual aiming
circuit 532 provides electronically adjustable inertia and dampening for
camera
movement in each of the three axes, with inertia and dampening separately
adjustable in each axis. Of course, these features may also be used only on a
single axis, or on two axes. If all three circuits 550, 552 and 554 are used,
they can be individually switched on and off as needed.
[00113] Fig. 37 shows an electronics box 442 for use with the manual
aiming system 530. Hand controls, such as joysticks on the control box 440,
are connected to the electronics box 442. Alternatively, the electronics box
442
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and control box 440 may be combined into a single unit, with e.g., joysticks
mounted directly on the combined box, as shown in Fig. 35. However,
preferably the electronics box 442 is a separate unit provided with inputs
from
a control panel or box 440 or other remotely located control devices, such as
joysticks, wheels, pedals, a mouse, or recorded playback media (tape, CD,
etc.). The switches 534 can be separately and independently switched on or
off, to provide manual or automatic control. When used, dampening and
inertia are preferably adjustable via knobs, dials, etc. 539 and 540 on the
control box 440. With the manual aiming circuit 532 switched on, the system
530 provides an adjustable inertia feel to the camera platform. Manual aiming
movement of the platform is resisted by the motor assemblies 475 in a way to
provide an inertia feel to the camera platform. The circuit 532 controls the
motor assemblies 475 based on feedback from the rate sensors 526, in a way
so that the camera platform responds to external forces as if the camera
payload has a much greater apparent inertia. As a result, during manual
aiming, if the inertia levels are turned up using the differentiator 540, even
large forces acting on the camera platform will produce slower and smooth
movements. This provides for smoother camera platform movement during
manual aiming. Similarly, the divider 536 provides adjustable dampening to
movement of the camera platform, much like hydraulic dampening, helping to
provide smooth camera platform movement even during manual aiming.
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[00114] In the manual aiming circuit 532, the divider 536 provides control
of the motor assemblies 475 to provide resistance to camera platform
movement which is proportional to the speed or rate of camera platform
movement, i.e., dampening. The differentiator 540 in the manual aiming circuit
532 controls the motor assemblies 475 so that they provide a resistance to
camera platform movement which is proportional to acceleration of the camera
platform, as detected by the sensors 526 (i.e., inertia). Consequently, to the
camera operator, the camera feels and reacts as if the camera is supported on
a fluid mounting head.
DRIFT COMPENSATION
[00115] Camera stabilization systems typically use sensors on the camera
platform for sensing rate or angular speed. These are typically fiber optic
rate
sensors. Due to slight inaccuracies in operation of the sensors, virtually all
stabilization systems have some degree of drift. Drift is unintentional
movement of the camera platform over time. Consequently, over longer
periods of time, for example, one hour, the camera position can drift or move,
even though. the. stabilization system is operating properly. As a result, if
there
is a significant delay in filming or video recording (for example, a lunch
break),
the camera may drift out of position. If unnoticed, this can result in errors
when filming resumes. If the drift of the camera is noticed, it must then be
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corrected by repositioning the camera. In either even, drift can result in
costly
loss of production time.
[00116] Referring to Fig. 33, a control system 560 is provided for reducing
or eliminating drift. The system 560 includes 3 separate circuits 562, 564,
and
566, for controlling drift movement in each of the pan, roll and tilt axes,
similar
to the system described above in connection with Fig. 35. As shown in Fig.
33, the camera stabilization system with drift control 560 uses conventional
gyrostabilization techniques, to provide the stabilization function.
Specifically,
a rate sensor 526 on the camera platform provides an output to a summator
570. Outputs from trim potentiometers 528 and from a control device 520 are
also input to the summator 570. The sum output from the summator 570 is
amplified by an amplifier 524 which drives a motor assembly 475, or pair of
motor assemblies. This provides feedback gyrostabilization of the camera
432.
[00117] To reduce or prevent drift, as shown in Fig. 33, a second sensor
568 is provided to detect movement about each axis. The sensor 568 is a
position sensor. For example, the sensor 568 may be an infrared reflective
sensor mounted on the pan frame 450 and facing the pan shaft gear 470. In
this way, the sensor 568 facing the teeth of the gear 470 can optically detect
incremental movement. The output from the drift position sensor 568 is
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provided into the drift compensation summator 570, and adds to the signals
from the control device 520 and trim potentiometer 528. Consequently, the
system shown in Fig. 33 having both a rate sensor 526 and a position sensor
568 associated with each pivot axis, is able to provide stabilization and
drift
control or drift compensation.
[00118] The drift position sensor 568 for detecting drift in the roll axis is
preferably supported on the roll collar 490 and detects movement optically via
the presence or absence of reflected light from the roll shaft gear 480.
Similarly, the drift position sensor 568 for detecting drift in the tilt axis
is
preferably supported on the tilt frame 458 and detects movement optically
relative to the tilt shaft gear 502.
PAN CONTROL WITH TILT SPEED CORRECTION
[00119] Referring to Fig. 34, as the camera platform is pivoted about the
roll axis 455, the rate sensor 526 for the pan axis 451 requires trigonometric
compensation, since the sensor 526 is no longer horizontal. For example, if
the system 430 is positioned as shown in Fig. 26, the pan axis 451 is parallel
with the tilt axis 459. In this position, if the camera operator, using a
joystick
520 tries to make a panning movement (i.e., to have the pan frame 450 pivot
about the pan axis 451), the tilt axis sensor will detect this movement as an
unintended deviation from the desired lens position. The system will therefore
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automatically compensate by pivoting the tilt frame by an equal an opposite
amount. The end result is no change in the lens angle, because the manual
control of the pan frame is cancelled out by the automatic control of the tilt
frame. With the roll frame at any angular position between zero, as shown in
Fig. 25, and 90 degrees, as shown in Fig. 26, the same cancelling of manual
pan movement also occurs, although to a lesser extent. For example, with the
tilt frame at an angle of 30 degrees (e.g., from horizontal), automatic
movement of the tilt frame will be opposite to and one half of pan movement
sine 30 = 0.5 ) as input by the camera operator. In the past, achieving
desired
manual pan movement, against the automatic counteracting movements of the
tilt frame, has been left up to the camera operator (via simultaneous manual
control of the tilt frame). However, this makes camera operator's job even
more difficult. As shown in Fig. 34, a compensated control circuit 580 is
provided to overcome this longstanding disadvantage. An output from a roll
angle sensor 582 senses the sine roll angle and provides it to a multiplier
584.
The pan axis control signal is also provided to the multiplier 584. The output
from the multiplier 584 is provided to a correction summator 586, along with
the outputs of the tilt axis control device 520 and the tilt axis sensor 526.
Accordingly, the output of the sensors 526 is compensated when the camera
platform on which the sensors are mounted is positioned at a non-zero roll
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angle. As a result, regardless of the angular position of the roll frame, all
of the
frames and the camera pan together.
AUTOMATIC LEVELING SYSTEM
[00120] With existing camera stabilization systems, in general, a signal
from a level sensor on the camera platform provides a reference causing the
camera platform to return to level or horizontal, whenever the control signal
from the control 520 is zero. For example, if the input control device 520 is
a
joystick, when the joystick is released and returns to center, the level
sensor
signal causes the camera platform to return to a zero position about the roll
axis. However, the camera operator may want the camera to remain at a non-
zero roll angle, even with the control device 520 released and at a zero
position.
[00121] In addition, if the camera platform is accelerated or decelerated,
e.g., at the end of a swinging crane arm, the level sensor signal will not
accurately return the camera platform to the zero roll angle, due to inertial
effects.
[00122] Referring to Fig. 32, an automatic leveling system 590 is provided
having three modes of operation. The modes of operation are selected using
a control panel 440. In the off mode, the system 590 operates using existing
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techniques. When the control device 520 is moved to a zero or center position
and has a zero output, the camera platform remains in whatever roll or dutch
angle it is in. In the normal mode of operation, the system 590 operates as
described above. That is, when the control device 520 has a zero output (for
example, a joystick released), the leveling circuit 596 causes the roll axis
motor(s) assembly 475 to return the camera platform to a zero roll angle.
[00123] In the fast mode, when the control device 520 has a zero output,
the leveling circuit 596 (a switchable/separable amplifier) causes the roll
axis
motor assemblies 475 to very rapidly return the camera platform to a zero roll
angle or horizontal. The fast mode is preferably engaged with a push button,
to rapidly level the camera about the roll axis. As shown in Fig. 32, in
addition
to the roll axis rate sensor 526, there is also a second sensor 595 for
sensing
position or inclination. In the fast mode, the leveling circuit 596 provides
an
output which rapidly brings the camera to horizontal (e.g., at 10
degrees/second), about the roll axis, whenever the output signal from the
inclination sensor is above a minimum threshold. When the inclination sensor
output is below the threshold value, but is not zero, (typically with the
inclination sensor sensing an inclination angle or 1,2,3,4 or 5 degrees) the
circuit 596 steps down to a second and slower levelling rate, such as '/2
degree/second, to avoid overshooting.
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GIMBAL BALANCING
[00124] Referring to Figs. 25-31, the term gimbal refers to the mechanical
linkage of the pan, roll and tilt frames and their interconnections. In use,
the
camera 432 is attached to the tilt frame 454. The vertical position of the
tilt
frame 454 is adjusted as desired by positioning the vertical or upright arm of
the tilt frame 458 in the sleeve 464 and tightening the sleeve bolts 466. The
camera is then balanced side to side or laterally on the tilt frame and locked
into position via the bolts 465 shown in Fig. 31. Balancing is continued by
loosening the roll frame locking bolts 86 and then moving the tilt frame 458
carrying the camera 432 side to side, until there is zero torque acting about
the
roll axis 455. The roll collar 490 and roll frame 454 are then pivoted 901,
from
the position shown in Fig. 25 to the position shown in Fig. 26. The center of
gravity of payload, i.e., the camera 432 is then again moved from side to side
until zero torque results about the roll axis 455. The locking bolts 486 are
then
tightened.
[00125] The camera 432 can then be stabilized using any of the systems,
circuits, and techniques described above in connection with Figs. 32-37.
Alternatively, existing known circuits may be used.
[00126] In comparison to previous types of systems, the system 430
shown in Figs. 24-31 provides improved convenience in balancing, has fewer
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pinch points providing increased safety in use, and is more compact and
lightweight.
[00127] Referring to Fig. 38, the motor assemblies 475 have gear trains
478 including conical bevel gears. The motor assemblies 475 are compact, to
reduce the moments of inertia of the frames supporting them, and to provide a
compact design. For providing movement about each axis, the pairs of motors
operate on offset amplified signals. The drive signal to each motor is the
same, although they are offset from each other. This provides for a linear
system and reduces or avoids backlash.
[00128] By locating the pan axis motors 472 and 474 on the pan frame
450, and by locating the roll axis motors 482 and 484 on the roll frame 454,
the
system 430 is made more compact and with less moment of inertia. This
allows for more rapid movements. The system 430 is also accordingly more
aerodynamically balanced. Consequently, there is less wind load on the
system.
BLOCK SWITCHING
[00129] During balancing, all motors must be turned off. Accordingly,
each time the payload changes, for example, by changing a lens on the
camera, power to all motors must be turned off and the system rebalanced.
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Accordingly, a block power switch 600 controlling power to all motors is
preferably provided near the camera, e.g., on the pan frame 450. This allows
the assistant camera operator to conveniently turn off power to the motors for
balancing. The block power switch 600 preferably controls only power to the
motors, and not to the circuitry or sensors.
[00130] The words pan, tilt or roll in the claims refers to the axis
associated with the element, and is not a description of any characteristic of
the element itself. The words pan, tilt and roll have their usual meanings, as
understood in the field of making motion pictures. However, they can
equivalently be replaced by first axis, second axis and third axis, where the
invention is used in non-traditional motion picture applications.
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