ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

of all abilities. Each player has their own characteristic interaction traces during the golf
swing. This interaction diagram, which utilizes correlating alignments of both the
generating lines of ISA and e3 can be directly applied to investigate the dynamics of the
player-club interaction, thereby offering an essential precursor to the improvement of
performance. We utilized the e3 in order to kinesthetically dictate the correct geometric
path of the inertia of the club, in contrast to the previous research where mostly the
contribution of individual segment(s) to the end effectors (e.g., e3 of the club) was
evaluated [14].
One of the major drawbacks to the biomechanical modeling of golfers has been
the application of full-body computer model to the actual game of golf. The full-body
generalized model [15] is easily influenced by tuning parameters such as contacts of
foot ground interface, muscle activation, and types of joint constraints. Moreover, these
generalized models are not representative of all players. Therefore we propose the screw
axes surfaces, that are less influenced by tuning parameters, may be the basis of swing
performance, and be the basis of, or allow for identification of each player’s
“signature.” The ISA’s of clubs have not been reported yet and are not currently
considered to be as important influencing factors for golf swing. We note, however, that
in the automobile industry, it has been proposed that the ISA surfaces for the car’s
suspension be included in the vehicle dynamics’ performance index [16]. While golf
shaft manufactures have previously used instrumented golf club in attempt to
understand the characteristics of each golfer’s swing, it is still unclear how to connect
shaft strain and actual swing performance. If the primary means of improving technique
of golf swing by learners is repetitive replication of certain trajectories, then, paying
more attention to the ISAs of the club in holistic terms, (as opposed to how the
segmental movements are produced, as in traditional golf research) could be important.
To our knowledge, this is the first time that the dynamic touch method of assessing golf
biomechanics has been used to assess differences in technique between elite and nonelite
players.
Presented as an equivalence of error covariance with inertia tensor, wobbling
inertia is directly related to the perturbation of error covariance. The latter may be
connected to uncertainty in probabilistic models in human sensorimotor control [17]
according to anecdotal evidence, and would indicate a measure in deviation from
established patterns, as we hypothesized. Wobbling inertia could be one of the factors
that would be able to confirm our conclusion that more swing to swing variability in
muscle activity and swing time exists in high handicap golfers[18]. It may also explain
why the significance of the left-hand extension during a golfer’s downswing is much
focused upon in traditional golf instruction of the golf down swing [19]. Potential uses
and applications of the perception to action diagram range from the reduction of club’s
wobbling inertia to optimally matching of golfer to specific equipment. Basically this
means that our system offers the advantage of allowing for the measurement of playerspecific
model rather than a generalized model.
Acknowledgments
The authors would like to acknowledge Miwon Kim, Sofia Camacho, and Professor
Jorge Infante, for their help during data acquisition for this study. The first author
should also like to thank Mr. Sangdo Kim for his stimulating discussions regarding the
perfection of the golf swing.
6. REFERENCES