Measuring and testing – Testing impact delivering device
Reexamination Certificate
2002-03-01
2004-06-29
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Testing impact delivering device
Reexamination Certificate
active
06755072
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a ball hitting tool testing device and more specifically to a testing device applicable to a ball-hitting tool such as a racket for tennis, badminton, squash, table tennis, a golf club, and a bat for baseball. In particular, the present invention relates to a testing device, which is preferably used for the tennis racket. With a robot gripping the tennis racket, the testing equipment device performs several motions of the tennis racket which is performed at the time of stroke by a person with the person gripping the tennis racket. Thereby the testing device allows quantitative evaluation of speed of the a ball at the time of a stroke, controllability, and spin performance.
BACKGROUND ART
Research has been made for a testing device of a ball-hitting tool such as the tennis racket so that the testing device has a function of hitting a ball in a state close to that in which a person actually hits the ball.
For example, the conventional testing device of the tennis racket is disclosed in the following books: Journal [No. 940-9] of the Japan Society of Mechanical Engineers, Symposium on AVD Lecture Papers, Page 128; Journal [No. 95-28] of the Japan Society of Mechanical Engineers, fourth meeting Symposium on Motion and Vibration Control Lecture Papers, Page 170; [No. 95-17] Journal of the Japan Society of Mechanical Engineers, Robotics and Mechatronics lecture, 1995 Lecture Papers (Vol.B), Page 1260; Journal [No.96-20] of the Japan Society of Mechanical Engineers, Symposium Lecture Papers, Page 35; and Nikkei Mechanical, May 15, 1995, No.454, Page 66.
The testing device of the tennis racket reported in the above-described books has a construction shown in FIG.
10
. The testing equipment is designed by considering that when a person performs a ball-hitting motion, with the human gripping the tennis racket, the tennis racket makes a complicated motion which is a combination of a translation motion and a rotary motion. The testing equipment is a horizontal two-joint robot having a minimum necessary degree of freedom to allow the translation motion and the rotary motion to be accomplished.
That is, in the testing device, the motor
1
rotates (rotation on S-axis) the first joint
2
directly in a direction shown with an arrow, the first joint
2
is connected to one end of the connection plate
3
, the second joint
4
is rotatably installed on the other end of the connection plate
3
, the first joint
2
and the second joint
4
are interlocked with each other with the timing belt
5
, and the motor
1
rotates (rotation on T-axis) the second joint
4
in a direction shown with an arrow. The holder
6
is fixed to the second joint
4
, and the grip
8
a
of the tennis racket
8
is inserted into and fixed to the holder
6
.
The testing device having the horizontal two joints is driven by one driving device (motor
1
). The rotation of the first joint
2
(corresponding to person's shoulder) on the S-axis and the rotation of the second joint
4
(corresponding to person's wrist) on the T-axis are synchronous with each other. The testing device can reproduce a ball-hitting motion of the tennis racket at a volley time in playing tennis.
As shown in
FIGS. 11 and 12
, the holder
6
has the shock-absorbing rubber sheet
2
disposed on the inner peripheral surface of each of the fixing parts
1
a
and
1
b
each made by dividing a metal cylinder into halves. With the grip
21
a
of the tennis racket
20
sandwiched between the fixing parts
1
a
and
1
b
through the rubber sheet
2
, the fixing parts
1
a
and
1
b
are clamped with the screw
3
to hold the tennis racket
10
thereby.
The testing device having two horizontal joints has been developed to measure the mechanical characteristic of the tennis racket at the time of a volley in playing tennis. Thus the tennis robot is capable of evaluating the performance of the tennis racket only at the time of the volley but is incapable of evaluating the performance of the tennis racket at the time of a stroke. In evaluating the performance of the tennis racket, the evaluation of speed of a ball, controllability, and spin performance at the time of the stroke are more important than the evaluation of the tennis racket at the time of the volley. As described above, since the conventional testing device has the horizontal two joints, it has a problem in that it is incapable of evaluating the performance of the tennis racket at the time of the stroke.
More specifically, a swing in tennis is made not in one swing plane but is varied because a player raises his/her body and lifts his/her arm. To spin a ball when the ball is served, it is necessary to angularly change the racket plane by inward rotating the arm. An effective volley can be made not only by hitting the ball with the racket plane vertical to the ground but also in combination of an angle change of the longitudinal axis of the racket to the ground by a vertical swing motion of the wrist and the outward rotation of the arm.
The testing, having two horizontal joints, shown in
FIG. 10
is incapable of reproducing several motions including a rotation-accompanied vertical motion of the tennis racket following a motion of the upper part of a player's body, a rotating motion of the tennis racket by a twist of the wrist caused by inward and outward rotation of the arm and a vertical motion of the wrist.
The collision speed of the tennis racket held by the testing device is as low as about 5 m/sec. Although description is made in the above-described books that the collision speed of the tennis racket held by the testing equipment is as high as 30 m/sec, the description is not substantiated.
The head speed of the tennis racket at the time of the stroke is 10-30 m/sec in regulation-ball tennis and 50 m/sec in softball tennis. The head speed of the tennis racket swung by a high-class player is faster by about 10 m/sec than that of the tennis racket swung by a beginner. The angular velocity of the high-class player's wrist is faster by 700°/sec than that of the beginner's wrist (page 70 through 77 of “New Science of Tennis” published by tennis journal).
The most conspicuous difference in players' swings is a swing speed and in particular the difference between swing speeds of wrists. Thus there is a demand that the testing equipment is capable of adjusting the head speed of the tennis racket in the range of 5-50 m/sec. However, as described above, since the collision speed in the testing equipment device is about 5 m/sec, the testing equipment is incapable of realizing a high head speed.
Depending on the high-class player and the beginner, the testing device is required to allow the rotation speed of the entire testing equipment and the rotation speed around the wrist to be freely adjusted. However, in the testing device shown in
FIG. 10
, since one motor drives the first joint and the second joint, the testing device is incapable of freely adjusting the rotation speed (rotation speed of the first joint) of the entire testing device and the rotation speed (rotation speed of the second joint) around the wrist independently and freely.
Further the holder
6
, made of metal and rubber, used in the testing device shown in
FIG. 10
is incapable of absorbing a shock and a strain applied to the holder
6
as a result of a collision between the tennis racket and the ball at the time of a high-speed swing. Thus in the case where the testing device conducts a ball-hitting test repeatedly, the tennis racket is broken at the shaft or the throat thereof.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-described problem. It is a first object of the present invention to provide a testing device, of a ball-hitting tool such as a tennis racket, which reproduces a motion of a tennis racket at the time of a stroke. It is a second object of the present invention to provide a testing device, which can adjust a ball collision speed from a low speed to a high spee
Kanemitsu Yumi
Nishibayashi Jun
Davis Octavia
Sumitomo Rubber Industries Ltd.
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