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Description  |
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BACKGROUND
1. Field of Invention
My invention includes both television and computer technology. As a golf
clubhead approaches a simulated golf ball, it is illuminated by three
flashes of a stroboscope and the images are registered on two color TV
cameras. The images are converted into digital data, analyzed by a
computer, and used to control a light spot on a TV screen to simulate the
ball's trajectory as seen by the golfer. The trajectory is superimposed on
a view toward the hole from the golfer's position. When the player is next
up the view changes to a view of the hole from approximately the ball's
new position.
2. Description of Prior Art
The systems proposed in the two patents described below have some
similarity to that described in this patent application. These patents are
included by reference in this application.
Gobush et al, U.S. Pat. No. 5,501,463: The intent is to measure the
parameters of a golf stroke and to display the measurements to the stroker
for his instruction. Since the system is portable, the system calibration
unit of Gobush FIG. 6 must be used at every set-up to define the geometric
relationship of the measurement system to the measurement volume
immediately behind the ball. The clubhead calibration unit of Gobush FIG.
7 must then be employed to define the clubhead parameters of the club to
be used. As shown in Gobush FIG. 5, the clubhead has at least two spots on
its outer surface and one facing outward on the shaft perhaps 1 inch above
the clubhead.
In Gobush FIG. 4, two TVs (18, 19), each with two flanking strobes (21, 22,
23, 24) are located perhaps 75 cm from the ball. The TV fields of view
converge to form a measurement volume extending perhaps 15 cm behind the
ball. A sensor is located behind the measurement volume to detect the
onslaught of the club. The sensor detects the clubhead as it approaches
the edge of the measurement volume. The strobes of both cameras are
simultaneously triggered twice with the intent of producing in the TV
cameras the images shown in Gobush FIG. 8. Since there is no provision for
adjusting the timing of the initial strobe flash or the interval between
it and the second, the range of measurement of the clubhead velocity and
other clubhead parameters is limited by the resolution of the TV cameras.
Within this limitation it is claimed that the two TV images may be used to
compute stroke parameters.
Tonner, U.S. Pat. No. 4,767,121: Only this patent's display system has any
relevance. As shown in Tonner FIGS. 10 and 11, a map of the hole is
displayed on a TV screen. When a "ball" is hit, its ground track
(apparently one of seven possible tracks as determined by the system's
measurement of the ball's impact and direction), yardage and and final
position are displayed. The final position is simply where it first
impacts the terrain. Apparently there is one correct physical direction
(e.g. one correct track), the same for all shots, in which the player
should hit the ball. When hit, the ball's ground track is traced on the
screen as determined by the measurement system. The foregoing has only a
slight resemblance to the proposed system.
SYSTEM COMPARISONS
The differences between my system and Gobush are:
My system uses permanent or detachable color-coded bars extending along the
lower rear and outer rear edges of the clubhead as shown in FIG. 2 of this
application. When strobed from the rear, the bars are so angled as to be
highly visible respectively from the X-Y TV color camera below and the Y-Z
TV color camera to one side.
The clubhead sensors, FIG. 3, sense the clubhead onslaught and measure its
approximate velocity along the X-Y TV's Y axis. This is used to control
the timing of the initial strobe flash and its frequency and duty cycle.
This permits use of the full camera field of view for all clubhead
velocities. Consequently the system can measure accurately the parameters
of strokes at very different velocities.
The two TV cameras are positioned at right angles to each other and to the
general direction of clubhead travel, as are the color-coded bars on the
clubhead. As compared to Gobush, this arrangement greatly simplifies
measurements and computations.
On the two TV cameras of my system, the positions and angles of the bar
images implicitly indicate clubhead velocity and acceleration, direction
of travel, vertical and horizontal positions as they change, hook/slice
and pitch angles as they change. The positions of the bar images and the
bar color coding indicating the club type and brand are digitized and
transmitted to the computer to define these parameters explicitly. Their
values at the last strobe are extrapolated to determine their values as
the clubhead strikes the ball. These and other data are used to determine
the ball's complete trajectory. This is presented as the golfer sees it on
a view of the hole from the golfer's location. When next up, the golfer in
essence is moved up to see a view toward the hole from approximately the
ball's new location. Gorbush simply provides digital readouts of stroke
parameters.
Owing to the profoundly different measurement techniques, the mathematics
used to derive the parameters of clubhead motion, direction, etc. as it
hits the ball are equally different.
The obvious differences between the proposed system and Tonner are:
The view of the hole in Tonner is simply a map that does not change. In my
system the player's view of the hole is in perspective as the golfer would
see it on the ground. Before each player's stroke the view changes to
present a view of the hole from the final position of his previous shot.
Tonner simply traces out the ground track of the shot from present position
to point of first impact with terrain. For internal use my system computes
ground track from present position to final position after bounces and
rollout and uses these and other data to present the total trajectory as
it would be seen by the golfer.
FIGURES--SUMMARY
FIG. 1 shows all elements of the system except the barred golf clubs and a
remotely located computer and associated video storage unit that serve
perhaps 100 venues.
FIGS. 2A, 2B, 2C show a golf clubhead with the two color-segmented bars
needed for system operation.
FIG. 3 shows the stroke measurement system. This consists of clubhead
sensors that detect the stroke and measure its velocity approximately, a
strobe, two color TV cameras to register clubhead parameters when the
strobe flashes, a tethered golf ball to serve as the target of the stroke,
and a computer-ontrolled support for the ball.
FIG. 4 shows the images of the clubhead bars on the X-Y and Y-Z TV color
cameras produced by three strobes of a typical golf stroke.
FIG. 5 represents in much simplified form a typical topographic map of a
golf hole stored digitally in the computer. The ground track of a typical
shot from the tee is also shown, as are the effective X-Y axes of the
stroke measurement system at the location of the next shot.
OPERATION
FIG. 1: This figure shows a single station layout. A central computer and
coupled video storage unit (not shown) are remotely located and can serve
perhaps 100 stations The stroke measurement unit electronic functions (not
shown) are executed locally. The clubhead (not shown here, see FIGS. 2A,
2B, 2C) has two color-segmented bars, one along its rear bottom edge and
the other on its outer surface. The stroke measurement unit (3) consists
of clubhead sensors, a stroboscope, a strobe control, a transparent plate,
an X-Y color TV camera to register the horizontal locations of the
clubhead at the three strobe flashes, a Y-Z color camera to register the
vertical locations of the clubhead at the three strobe flashes, and a
tethered ball on a computer-controlled variable-height post and
surrounding "grass" (see FIG. 3).
The players use a manual input unit (4), a simple keyboard and display with
menus, to enter initial and other data to the computer and control the
course of the game if desired. Several golf courses will be available.
Among the options available are: golf course, hole and view to be played,
golf brand and club used (overrides clubhead color codes), wind
conditions. The display and printer unit (5) first displays the player up,
his distance to the hole, his score, and wind force and direction. After
his stroke, the display indicates all stroke parameters, yardage, new
score. The rear-projection color TV (6) or equivalent TV display unit is
controlled by the computer and video storage unit first to present on the
screen (7) a view of the hole corresponding to the location of the
player's ball. Then, almost instantly after each stroke, the computer
causes the TV to superimpose on this view the golfer's view of the ball as
it traces out its trajectory in accordance with the club and stroke
measurement data, terrain, course condition and wind. At the conclusion of
the game the printer provides for each player stroke and score data on
each hole and final position for each hole on a putting green. The players
then proceed to the green, place their balls per the recorded final
position for each hole, and putt to finish the game.
FIGS. 2A, 2B, 2C: These clubs have all the capabilities of standard golf
clubs and can be used equally well in the field. They differ from standard
clubs in that they have color-segmented bars, straight or curved, in or on
the lower rear and outer rear edges or surfaces of the clubhead. These may
be permanent or may be adhered to or inserted in the clubhead in a variety
of ways, one of which is shown. If inserted, they may be keyed with
notches in the bars and protrusions on the clubhead or vice versa such
that only the appropriate color bar can be inserted in the clubhead.
Conversely, "skeleton" color bars can be used to have the same club
counterfeit other clubs.
A sequence of colors in the color bars constitutes a code identifying both
the type and brand of club. Data defining the performance of clubs by type
and brand are stored in the computer and contribute to computing ball
trajectory. The strobe illumination, the colors of the bars and the TV
tube sensitivity may all be outside the visible spectrum.
FIGS. 3, 4, 5: The functions separately described in these figures are more
apparent if their interrelationships are briefly described.
The locations and color sequences of the images on each TV tube produced by
the strobe flashes are converted locally into digital data and transmitted
to the central computer. The computer analyzes the relative positions and
angles of the images to generate data describing clubhead parameters as it
strikes the ball. These plus parameters. The total ball trajectory
consists of a series of mini-trajectories. T1 is the initial flight, T2
the first bounce, etc. T1 is determined by the stroke parameters and the
effect of wind. T2 is determined by the terminal conditions of T1
including ball spin, sector types such as fairway, rough, trap or green,
sector degree and direction of slope, and course condition--hard, moderate
or soft. T3 is determined by the terminal conditions of T2 and the other
parameters listed.
When the final position of the ball is within a given terrain sector,
within the computer the ball is placed at that sector viewpoint for the
next shot. When the player is next up, the view on the screen provided by
the video storage unit under computer control changes to the view toward
the hole from that viewpoint.
This procedure requires manipulation of data in three coordinate systems.
The stroke measurement data are with respect to the axes of the X-Y and
Y-Z axes of the TV tubes. Their significance with respect to the map
depends on the location and orientation of these axes with respect to the
map. Since this is known, the data with respect to the camera axes
determining the initial trajectory can be converted to the map axes to
compute the ball's total trajectory and final location on the map.
Since the view toward the hole on the screen corresponds to the simulated
position of the stroke measurement system on the map, the screen and TV
axes are the same except that the screen axes are in perspective. The
trajectory data calculated with respect to the axes of the map are
converted to the same data with respect to the screen image and
transformed into the movement of a light spot on the screen simulating in
time the ball's trajectory as it would be seen by the golfer. Another
approach is to convert both map and measurement system axes to screen axes
before the stroke and compute accordingly. Which technique is used is a
matter of mathematical and computational convenience.
FIG. 3: The stroke measurement subsystem consists of a clubhead sensor
assembly (3-1, 3-2) a stroboscope (3-3), a transparent plate (3-4), two TV
color cameras (3-5, 3-6), and a tethered ball (3-7) on a
computer-controlled support (3-8) surrounded by artificial grass.
The clubhead sensor assembly consists of two photocell sensors, (3-1, 3-2),
logic and an electronic clock. The clubhead backswing photocell signal
sequence, 3-2 - 3-1, is used by the logic component to trigger the two TVs
for one sweep to delete optical noise and to reset the clock. The forward
swing signal sequence, 3-2 - 3-1, operates through the logic unit to start
and stop the electronic clock. Since the clock counts down from perhaps
1000 at perhaps a rate of 1 kHz, its final value is a measure of clubhead
velocity.
Clubhead velocity can range from perhaps 75 m/sec to 1 m/sec. For maximum
measurement accuracy it is desirable to use the full field of view of the
TV cameras regardless of clubhead velocity. For this reason a strobe
control uses the clock count supplied by the clubhead sensor assembly to
trigger flashes when, for all velocities, the clubhead is in approximately
the same three positions with respect to the transparent plate. Assuming
that the transparent plate extends about 44 cm along the Y axis, three
flashes could be located at 10 cm intervals with a 6 cm margin at the rear
and an 8 cm margin at the forward end to allow for clubhead acceleration.
The flash durations, inversely proportional to clubhead velocity, are such
as to produce an image width on the TV tubes equivalent to perhaps 3 mm
along the Y axis of the plate.
The strobe and cameras may operate operate outside the visible spectrum.
The stroboscope function may also be achieved by using a continuous beam
of light from the stroboscope location and using the velocity datum from
the clubhead sensor assembly to control the gating times of the TV
cameras.
The X-Y TV camera (3-5), located perhaps 75 cm below the transparent plate,
registers clubhead positions in the horizontal plane. The Y-Z TV camera
(3-6), located perhaps 75 cm from the side of the transparent plate away
from the golfer, registers clubhead positions in the vertical plane. For
left-handed golfers the Y-Z camera could be pressed into the floor,
causing a coresponding camera to rise on the other side of the plate. The
fields of view of the two cameras intersect to form a measurement volume
perhaps 45.times.45.times.45 cm.
Immediately after the third flash the two TV cameras are scanned, one after
the other, along the Y axis. The location of each pulse is defined by the
scan line, X or Z value, and the time within the scan line, Y value, at
which it is encountered. A digitizer converts these to the appropriate
digital format. Each pulse color value, also converted to a digital
signal, is addded as a tag to the pulse data. To eliminate unneeded data,
after each pulse return further returns are ignored for a time equivalent
to perhaps 5 cm of line scan of the transparent plate. All data plus
strobe frequency are transmitted to the computer.
The tethered golf ball (3-7) is mounted on a computer-controlled support
(3-8). Its vertical position is above, on, or at different depths in the
surrounding "grass" depending on whether the stroke is to be from the tee,
the fairway, the rough or a trap. When hit, the support transmits a signal
to the central computer to confirm that a stroke has in fact been made.
After the stroke the ball is automatically returned to its position on the
support.
FIG. 4; The nomenclature for this Figure is:
S1, S2, S3 The images formed on the two TV tubes by the strobe flashes
M1-2, M2-3 Computed curve connecting the midpoints of S1, S2, S3. The two
arcs are measured and analyzed to indicate the direction, velocity and, by
comparing them, the accelerations of the clubhead in the horizontal and
vertical planes. This curve also indicate the transverse and vertical
location of the clubhead as it hits the ball.
VP The three images (S1, S2, S3) of the X-Y color bar should be
perpendicular to the arc of clubhead travel in the X-Y TV tube. VP, the
variation from perpendicularity, is the angle of hook or slice. In the Y-Z
plane the arcs may or may not be parallel to the clubface pitch angle. Any
variation by club type and brand is included in the stored data describing
the club. The actual angle of the Y-Z color bar is compared to its nominal
value to determine the actual clubface pitch angle. The values of VP (if
any) at S1, S2, S3 in both X-Y and Y-Z planes are computed and the rates
of change determined.
How these values are manipulated depends upon the degree of accuracy
desired. For example, although the clubhead is moving in three dimensions
it will probably be sufficient to compute its velocity and acceleration at
S3 in the X-Y plane and multiply by a fudge factor of perhaps 1.05 to
account for its velocity and acceleration in the Z plane. However, for
maximum accuracy the curves connecting the midpoints in both planes can be
combined to form an equation defining the clubhead trajectory in three
dimensions. The arc of this trajectory can be computed and used to
determine precise clubhead velocity and acceleration. These can be
extrapolated from S3 to the ball. The values of clubhead location,
direction, VP, and their accelerations are also extrapolated from the
clubhead at S3 to the ball. The extrapolated locations of the X-Y and Y-Z
color bar midpoints at time of contact define the lateral and vertical
location of the clubhead at that time. The VP values indicate clubface
hook/slice and pitch angles. The direction of clubhead travel indicates
the initial direction of the ball trajectory, although this may be
modified by clubface angles and horizontal and vertical clubhead position.
The quantitative significance of these measurements on a golf ball's
trajectory must be determined largely by experiment.
FIG. 5: The terrain of each hole is mapped into sectors. These can be
defined by the locations of their vertices or by equations defining their
sides. Within each sector is a viewpoint. When the final position of the
ball is within a sector, a view toward the hole from that sector's
viewpoint is displayed when that player is next up.
In addition to its boundary data, each sector is defined by data that
include:
Precise location and orientation of its viewpoint, the ball's location for
the next shot.
Type of terrain: Tee, fairway, green, rough, trap, water, woods.
Direction and degree of sector slope
If the viewpoint is in a trap or there are other obstacles, direction and
elevation of the ball trajectory needed to emerge.
If the ball is in water or if it fails to emerge from a trap after two
tries, the ball is repositioned at another viewpoint at the cost of an
additional stroke.
Identification of screen view corresponding to viewpoint.
X and Y perspective equation(s) of view on TV screen.
In this figure T1 of the total trajectory terminates on the fairway, T2 in
a rough sector. Also shown are the location of the resulting sector
viewpoint and the orientation of the X-Y TV camera's measurement axes
implicit in that viewpoint.
The total ball trajectory is computed in two ways for two purposes: the
ground track to establish the ball's final position, the screen trajectory
to show the ball's trajectory from the golfer's point of view. In the case
of a stroke from the tee, the stroke measurement axes coincide with the
map axes and the stroke parameters can be used directly to compute the
ground track. When the stroke is from another viewpoint, the stroke
parameters can be transposed from the position and orientation of that
viewpoint to the corresponding values with respect to the map axes in
order to compute the ground track.
The screen view must be related to the hole map in order to have the ball's
screen trajectory reflect its terrain encounters. To do this, the hole map
of that portion of the hole displayed on the screen can be first
transposed to the viewpoint axes and thence to the screen axes. The
viewpoint's X axis corresponds to the screen's horizontal dimension, the Y
axis to the vertical dimension. However, both axes on the screen, like the
view shown on the screen, are in perspective, and the axes of the
transposed map in the computer must reflect this perspective.
Alternatively, the hole map within the scope of the viewpoint may be
transposed before the stroke to the viewpoint axes as seen in perspective
on the screen and all trajectory computations made accordingly.
* * * * *
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