U.S. patent number 3,855,842 [Application Number 05/361,005] was granted by the patent office on 1974-12-24 for apparatus for testing golf clubs.
This patent grant is currently assigned to Sumitomo Rubber Industries, Ltd.. Invention is credited to Junpei Imabori, Takeshi Kuzuoka, Atsuhiko Mori.
United States Patent |
3,855,842 |
Imabori , et al. |
December 24, 1974 |
APPARATUS FOR TESTING GOLF CLUBS
Abstract
An apparatus for testing the dynamic performance of a golf club
by simulating human golf swings including an arm driven by a first
motor for simulating the rotation of the golfer's arms about his
body and a club holder driven by a second motor for simulating the
rotation of the golfer's wrists about his arms. The arm and club
holder may be driven independently.
Inventors: |
Imabori; Junpei (Nishinomiya,
JA), Kuzuoka; Takeshi (Kobe, JA), Mori;
Atsuhiko (Osaka, JA) |
Assignee: |
Sumitomo Rubber Industries,
Ltd. (Kobe-shi, Kyogo, JA)
|
Family
ID: |
12884493 |
Appl.
No.: |
05/361,005 |
Filed: |
May 16, 1973 |
Foreign Application Priority Data
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|
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May 24, 1972 [JA] |
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47-51351 |
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Current U.S.
Class: |
73/11.01;
73/865.3; 73/12.02; 73/12.04 |
Current CPC
Class: |
G01M
99/00 (20130101); G01N 3/00 (20130101); G01N
2033/008 (20130101) |
Current International
Class: |
G01N
3/00 (20060101); G01M 19/00 (20060101); G01N
33/00 (20060101); G01m 003/00 () |
Field of
Search: |
;73/432SD,65,13
;273/186A ;35/29A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
S W. Herwald, Fundamentals of Servomechanisms How to Select and
Apply Them, June 1946, 7 pages..
|
Primary Examiner: Queisser; Richard C.
Assistant Examiner: Ciarlante; Anthony V.
Attorney, Agent or Firm: Sughrue, Rothwell, Mion, Zinn &
Macpeak
Claims
We claim:
1. An apparatus for testing dynamic characteristics of a golf club,
said apparatus comprising:
a. a main body;
b. arm means rotatably mounted on said main body, said arm means
swinging relative to said main body;
c. club holder means for holding said golf club and rotatably
mounted on said arm means, said club holder means rotating relative
to said arm means;
d. first drive means for rotating said arm means independently of
said holder means;
e. second drive means independent of said first drive means, for
rotating said holder means independently of said arm means; and
f. signal generator means for applying first and second program
signals to said first and second drive means, respectively, whereby
said drive means are controlled independently of each other by said
program signals so that a plurality of golf club swing patterns may
be simulated by the combination of independent operations of said
first and second drive means.
2. The apparatus as set forth in claim 1 wherein each of said first
and second drive means comprises:
a. potentiometer means coupled to the associated drive means for
producing a position signal indicative of the actual angle of
rotation of the drive means; and
b. servo-amplifier means for receiving and comparing corresponding
program and position signals to produce an error signal which
causes the drive means to assume the actual position called for by
the value of the program signal.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for testing the
dynamic characteristics of a golf club by swinging of the golf club
in a manner simulating swing patterns of human golf players.
2. Description of the Prior Art
It is necessary in designing golf clubs for higher quality to test
the dynamic efficiency or a property of a golf club which is
appropriate for a particular swing form or pattern. This is because
there are so many swing patterns among different golf players. For
test purposes, absolutely identical swing patterns should be
repeated. However, this requirement cannot be fully met by the
human golf players because the reproducibility of a particular
swing pattern is poor. Another difficulty resides in that one test
player can present only one swing pattern at the most, and as such
it is impossible to attain a variety of swing patterns.
SUMMARY OF THE INVENTION
According to the present invention, the difficulties encountered in
testing golf clubs are eliminated, and a wide variety of swing
patterns simulating those of human players are automatically
obtained with complete and exact reproducibility.
Swinging motion, more specifically the downswing, of a golf club is
composed of two motions: one is a rotational motion performed by a
player in a plane inclined relative to the horizontal and including
an over-head position in which the club-head is over the player's
head with his body fully wound up and a hitting position in which
the club-head just approaches impact with the golf ball with the
player's body uncoiled. The other motion is also a rotational
motion performed in the above plane concurrently with the former
motion but its center of rotation is located at the moving wrists
of the player. The apparatus according to the invention correctly
simulates and puts the above two rotational motions into
effect.
The main feature of the present invention resides in an apparatus
for testing the dynamic efficiency of a golf club comprising an arm
portion and a club-grip holder both adapted to firmly hold the grip
of a golf club and to swing independently of each other with
respect to a relatively stationary main body so that the golf club
is caused to experience the composed swinging motion with respect
to the two different centers of rotation; and driving means
responsive to an electric control signal for effecting the
independent swinging motions of the arm portion and of the
club-grip holder.
The apparatus according to the invention is thus composed of a
mechanical portion adapted to set a golf club and to cause the same
to swing, and of an electric control portion adapted to effect the
swinging motion of the golf club in a fashion to simulate a variety
of swing patterns of human golf players.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an apparatus for testing dynamic
characteristics of a golf club according to the invention.
FIG. 2 is a cross-sectional view taken along the line A--A' of FIG.
1.
FIG. 3 is an enlarged perspective view of an embodiment of a golf
club grip holder as used in the apparatus of FIG. 1.
FIG. 4 is an explanatory view showing analyzed swing angles of a
golf club when a human player makes a downswing of the club.
FIG. 5 shows characteristic curves of the swing angles of FIG. 4
which are plotted against time during the time interval between the
initiation of the downswing and the instant of impart with a golf
ball.
FIG. 6 is a block diagram showing a programmed signal generator
used with a mechanical portion of the apparatus of FIG. 1.
FIG. 7 is similar to FIG. 6 but shows a displacement servo system
as used with the signal generator of FIG. 6.
FIG. 8 is a graph showing the waveforms occuring in certain
portions of FIG. 6.
FIG. 9 is a schematic diagram of the poteneiometer shown in FIG. 7.
potentiometer
FIG. 10 is a block diagram of the electric control portion of the
invention .
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 1, a relatively stationary main body includes a
motor casing 7 fastened to one of coupled supporting posts 9 and
movable up and down by turning a jacking handle (not shown). The
other of the supporting posts 9 is secured to a base 20 provided
with a plurality of foot members 10 and with a plurality of tires
11 used for moving the apparatus as a whole. At each lower end of
the foot members 10 is a locking member 19 which is threaded for
locking the position of the apparatus. A tilting handle 8 is
mounted on the upper end of the supporting post 9 and is manually
turned for controlling the inclination of the motor casing 7 with
respect to the horizontal.
Turning now to FIG. 2, two electric motors M.sub.1 and M.sub.2 are
installed within the motor casing 7. Two pulleys 14 and 15 are
rotatably mounted on shaft 21 driven by the motor M.sub.1 and an
arm portion 5 is secured to the extending end of shaft 21. The
pulleys 14 and 15 may be preferably integral or coupled with each
other so as to rotate simultaneously. A pulley 13 is secured to a
shaft 27 driven by the motor M.sub.2. A club-grip holder 4 and a
pulley 12 are secured respectively to a shaft 22 on the outside and
inside of a casing 6 of the arm portion 5. Two endless belts 17 and
16 are respectively between pulleys 13 and 15 and between pulleys
14 and 12.
With this construction, the driving force of the motor M.sub.2 is
delivered from the pulley 13 through the pulleys 15 and 14 to the
pulley 12, thus rotating the shaft 22. This rotational motion is
then applied to the grip holder 4 and accordingly to a golf club
which includes a grip portion 3, shaft portion 2 and head portion
1. The golf club is fastened in advance to the grip holder 4. The
club is caused to swing about the shaft 22 which corresponds to the
center of rotation of the player's wrists. The driving force of the
motor M.sub.1 is directly delivered to the arm portion 5 through
the shaft 21, which corresponds to the center of rotation of the
player's body. Thus, the golf club can swing with the two centers
of rotation independent of each other. Therefore, it will be easily
understood that a variety of desired swing patterns, correctly
simulating those of human players, are obtainable if the motors
M.sub.1, M.sub.2 are properly controlled.
As shown in FIG. 3, the grip holder 4 is composed of two similar
plates 24 respectively having a groove of semicircular
cross-section sized to receive the grip portion 3 of the golf club.
After having interposed the grip portion 3 between the grooves, the
mating plates 24 are clamped by a suitable locking means such as a
plurality of bolts 23.
The operation of the mechanical portion of the apparatus is
electrically controlled by an electric control portion in a manner
as will be explained in the following. In order to attain a wide
variety of swing patterns correctly simulating those of human golf
players, the rotation of the motor M.sub.1 should closely simulate
the movement of the player's wrists, while the rotation of the
motor M.sub.2 should closely simulate the swinging motion of a golf
club with respect to the moving wrists.
For these simulating purposes, the movement of the wrists or arms
and the swinging motion of the club both during the downswing are
diagrammatically analyzed in a manner as shown in FIG. 4. Here, let
it be assumed that the angles of rotation taken by both of the
player's arms and of the club relative to the player's wrists
during a time interval between the initiation of the downswing and
the impact of the club head with a golf ball are respectively
denoted by .theta. and .phi.. These two angles .theta. and .phi.
are converted into electric signals, which in turn are introduced
into respective programmed signal generators, one of which is
illustrated in FIG. 6. A programmed signal thus produced in a
generator as a voltage signal is then delivered to a
servo-amplifier, an SCR trigger unit (phase control) and an SCR
unit electrically connected to an A.C. power source as shown in
FIG. 7. The output of the SCR unit is applied to the corresponding
motor M.sub.1 or M.sub.2 to effect the rotational operations in a
finely controlled fashion. The controlled rotations of the motors
will lead to the swinging motion of a golf club, as has been
described. The swinging motion thus obtained is observed by
suitable potentiometers, one of which is shown in FIG. 7. Each
potentiometer converts the characteristics of its associated motion
into a voltage signal which in turn is fed back to the
servo-amplifier and compared there with the programmed signal to
produce an error signal which causes the motor to follow the
programmed signal. In this way, inconsistency is eliminated between
the obtained swinging motion and the simulated motion expected to
be obtained in accordance with the input signals corresponding to
the angles .theta. and .phi..
A programmed signal generator, as shown in FIG. 6, can preset a
desired angle of rotation in terms of electric potentials (E.sub.1,
E.sub.2, E.sub.3, E.sub.4 - - - E.sub.n), which are determined by
resistance levels of a potentiometer corresponding to a number of
segments of the time interval as previously defined. The preset
potentials are then applied in consecutive order of the segmental
time intervals so that a stepped waveform resembling a desired
curve (see FIG. 5), which indicates the angle of rotation plotted
against time during the downswing, may be obtained. With reference
to FIG. 6, more specifically, a stepped waveform signal is
transmitted into an automatic tangent determining circuit, formed
by the subtraction integrator and sample-and-hold circuit, to
produce a tangential waveform resembling the particular curve.
FIg. 8 illustrates the waveforms present at points A, B, C and D in
FIG. 6.
Waveform C indicates the value of a prior step of waveform B
immediately after a clock pulse. Since the sample and hold circuit
samples and holds the value of the waveform c, the value of
waveform D is kept constant until the following sample instruction
or clock pulse occurs, even if the value of waveform C varies in
accordance with the lapse of time. Accordingly, the difference
between the inputs B and D in the subtraction integrator is the
difference in height of the steps at the preceding and following
clock pulses. The slope or tangent of the integrated output C is
directly proportional to the difference between B and D, and the
value of C equals the value of B immediately before the following
clock pulse. Though being constant, the period of the clock pulse
is increased twice or ten times for a slow-motion swing. Therefore,
the integrating constant of the subtraction integrator may be
changed by interlocking it with the change-over switch for
slow-motion.
Referring to FIG. 7, the servo-amplifier may preferably be used
with a control element of the SCR type, in which the three phase
electric energy is supplied from the power source and rectified.
With use of this SCR system, the electric control portion can feed
a control signal of sufficiently high voltage and of sufficiently
high instantaneous electric current to the mechanical portion,
especially the motors. However, this SCR system is not necessarily
indispensable; other control units using electronic elements such
as transistors may be used for rectifying the high three phase
electric energy. In order to improve responsiveness of the
apparatus, it may be preferable to increase the frequency of the
power source. Moreover, the motors may preferably be used with a
reduction unit to minimize the resultant inertia.
A detailed description will now be made of the embodiment of the
present invention in which the SCR control system of FIG. 7 was
employed for rectifying the electric energy of the three-phase
power source. The power source used was of the type having the
maximum voltage of 180 volts, the maximum instantaneous current of
100 amperes, and a frequency of 400 Hz. If, however, a suitable
generator is obtainable as the power source, the output frequency
may preferably exceed 1000 Hz. The motors used were of a minimum
inertia type motor, made by Yasukawa Electric Company, Ltd., which
was designed to minimize the moment of inertia of the rotor. The
motor M.sub.1 for controlling the angle .theta. had the maximum
instantaneous torque of 2.5 kg.m and was used in combiantion with a
reduction gear unit having a reduction ratio of 1/17. The motor
M.sub.2 for controlling the angle .phi. had a maximum instantaneous
torque of 1.3 kg.m and a reduction gear unit having a reduction
ratio of 1/11. Since both of the angles .theta. and .phi. were
controlled within a range of 200.degree., the feed-back detector
used for observing each of the obtaining swing motion was a
potentiometer of the type controlled by a single turn of its shaft.
The SCR trigger unit was a thyristor gate FS 3G 24-B, made by
Nippon Electric Co. The manner in which an SCR unit is triggered
relative to the phase of an applied A.C. wave to control the power
applied to a motor is well known. The embodiment as described
hereinbefore revealed that the apparatus according to the present
invention can produce the desired result.
FIG. 9 schematically illustrates one form of potentiometer which
may be used to observe the actual swinging motion of the club.
The motor shaft 21 of arm portion 5 and the motor shaft 22 of the
grip holder 4 are respectively coupled directly to the rotating
sliding contact 30 of the potentiometer either directly, or
indirectly through a non-slip belt, for example. Consequently, the
angle of rotation of the slider contact 30 corresponds exactly to
that of motor shafts 21 and 22.
In the schematic diagram of FIG. 9, a constant voltage E is applied
to the terminals A and B. When the sliding contact connected to
output terminal C traverses the resistance R in accordance with the
angle .alpha. of rotation of a driving shaft, the resistance value
r between terminal B or B' and terminal C is directly proportional
to the angle .alpha..
Accordingly, the voltage e between terminals C and B' becomes e =
r/R .times. E; i.e. voltage e is proportional to the angle .alpha.;
or as applied to this invention, the voltage e is proportional to
the rotating angle .theta. of the shaft 21 or arm portion 5 or to
the rotating angle .phi. of the shaft 22 of the club-grip holder
4.
FIG. 10 is a block diagram illustrating the manner in which the
proportional signal generators (FIG. 6) and the SCR control systems
(FIG. 7) are interconnected to form the complete electric control
portion of the invention.
Since the apparatus of the invention employs programmed signals for
controlling the operations of the mechanical portion, the change of
the swing angles during the time interval of the downswing can be
set more freely within its maximum angular displacement and
acceleration than in the conventional automatic testing apparatus
of a purely machanical type. Moreover, the swing angle change can
be easily performed by turning a set dial, thus providing for a
wide variety of programmed swing patterns. The electric control
portion of the apparatus is supplied with voltage signals dictated
by the programmed angle changes during the time interval, and
includes so-called displacement servo systems in which the
resultant angular displacements of the golf club closely follow the
commanding voltage signals. As a result, the programming can be
carried out without any complicated calculation, and as such a
servo system is considerably better than a conventional pneumatic
servo system which is very complicated. It should be understood
that the source of driving force is not limited to the D.C. motor
as used in the example but may be a hydraulic pressure motor
controlled by an electric signal. In addition, the apparatus of the
invention may desirably be used with a photo-electric pick-up
device which is positioned in the vicinity of the impact point of a
golf ball so as to detect and record the velocities of a golf club
and the ball both at the instant of the impact.
While the invention has been particularly shown and described with
reference to the preferred embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention.
* * * * *