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Herbert Hatze
09-27-1995, 11:10 PM
Subject: DISCUSSION-FORUM on the ISB Recommendations for
Standardization in the Reporting of Kinematic Data

In the October-1995 issue of the Journal of Biomechanics appeared on
pages 1257-1260 the "ISB RECOMMENDATIONS FOR STANDARDIZATION IN THE
REPORTING OF KINEMATIC DATA" presented by G. Wu and Peter R. Cavanagh
on behalf of the ISB-Standardization and Terminology Committee. The
recommendations are followed by an EDITORIAL COMMENT written by R.A.
Brand.

Among other proposed definitions are the recommended directions of the
global (resp. local segmental) right-handed Cartesian axes: the
+Y-axis pointing upward and parallel with the field of gravity
(+Yi-segmental axes pointing towards the proximal joint of a
segment), the +X-axis pointing in the forward direction to the right
(the +Xi-axes in the anterior direction), and the +Z-axis sidewards
and perpendicular to the XY-plane (and similarly the +Zi-axes).

This proposed convention ignores and contradicts all international
standards and commonly accepted practices in physics, mechanical
engineering, Lagrangian dynamics, applied mathematics and, most
important, also in biomechanics. The following spatial (and hence also
segmental) Cartesian coordinate system(s) is (are) commonly adopted:
the X-axis points sidewards (in the direction of the ISB-proposed
Z-axis), the Y-axis in the forward direction, and the Z-axis upwards
in the vertical direction.

Here follows a small sample of English (American)-language and
internationally renowned textbooks and works in which this spatial
coordinate system is used: L.K. Branson:ENGINEERING MECHANICS, Simon
and Schuster, New York, 1970, p. 3; R.Resnick and D. Halliday:
PHYSICS (parts I and II), John Wiley, New York, 1966, p. 302; D.A.
Wells: LAGRANGIAN DYNAMICS, Schaum Publ., New York, 1967, p. 181; H.
Goldstein: CLASSICAL MECHANICS, Addison-Wesley, 1969, p. 94; J.L.
Synge, B.A. Griffith: PRINCIPLES OF MECHANICS, Mc Graw-Hill, New
York, 1959; P. Allard, I.A.F. Stokes, J. Blanchi: THREE-DIMENSIONAL
ANALYSIS OF HUMAN MOVEMENT, Human Kinetics, 1995, p. 147; J.
Wittenburg: DYNAMICS OF SYSTEMS OF RIGID BODIES, Teubner, Stuttgart,
1977, p. 21.

I am unable to understand why the ISB can make recommendations which
not only grossly contradict international standards but also ignore
the e-mail discussions of a few years ago, in which a number of
colleagues (including me) proposed this universally accepted
coordinate system which has already been used in the creation of
three-dimensional human body models. In addition, the ISB-recommended
coordinate system necessitates an awkward sequence of rotations in
obtaining the rotation matrix: rotation about the Z-axis first,
followed by Y and X, while the common and logical sequence is (e.g.
for Cardan angles) X, Y, Z. Finally, it should be pointed that most
manufacturers of force plates also use this reference frame for
defining ground reaction force components.

Any biomechanist, who uses the ISB-proposed coordinate system in
publications submitted to international engineering, mechanics,
mathematics or similar journals runs the risk of being heavily criticized
for not adhering to international conventions.

I feel that this issue is certainly worth being discussed in this
forum. In fact, in my opinion, it would have been wiser to discuss the
ISB-recommendations within the scientific community before their
publication in the Journal of Biomechanics.

H. Hatze, Ph. D.
Professor of Biomechanics, University of Vienna, Austria.

H. Hatze
10-06-1995, 01:15 AM
SUBJECT: ISB RECOMMENDATIONS FOR THE STANDARDIZATION
OF THE REPORTING OF KINEMATIC DATA - RESUME OF
THE BIOMCH-L DISCUSSION FORUM OPENED BY
H. HATZE ON 28 SEPT. 1995

Instead of presenting a summary listing of all BIOMCH-L contributions


to the above topic, I shall attempt to give an objective resume.

A total of 19 contributions was received which includes those
directed to my personal e-mail address. Of these 19 contributions, 15


(or 79%) expressed outright rejection of the proposed ISB recommend-
ations, in some cases rather emphatically ("We have no intention of
ever using the proposed (ISB) conventions"). Of the remaining 4
contributions only one (that of Dr. Jack Crosbie of the University of


Sydney) expressly supported the ISB standard, while in 3
communications (those of Barbara van Geems, South Africa, Hamid
Rassoulian, Dr. J. H. Lawrence III, University of Kentucky) arguments


were presented that could possibly be classified as partial support
for some aspects of the ISB recommendations.

I shall now briefly react to the arguments put forth in the 4
communications that could be seen as support for the proposed ISB
conventions.

Dr. Crosbie's argument rests on the 2D-presentation of motions in
the plane of progression which, in his opinion, should be the
XY-plane. A similar argument is also used by Wu and Cavanagh on page
1258 of their J. of Biomechanics paper with the addition that such a
presentation "... will be consistent with the three-dimensional
convention." If the internationally adopted 3D-convention for
Cartesian axes systems is meant then this statement is not true as I
have shown by means of many examples from the international
literature. In addition, and in complete agreement with the opinion
expressed by Dr. Scott Tashman of Case Western Reserve University
("3D analysis is a completely different world than 2D analysis" and
"... basing a 3D standard on 2D conventions makes little sense"), 3D
analysis and simulation are the dominating techniques in todays
biomechanical research which fact should be used as point of
departure for any standardization attempt. Also, in any
two-dimensional (sideward) motion in the CORONAL PLANE, the YZ-plane
(in the ISB convention) would be the plane of progression and
therefore the XY-plane argument completely breaks down, although such


a motion analysis would certainly qualify as a ligitimate 2D-motion
analysis, albeit in the coronal plane. The remarks just made also
pertain
to the opinion expressed by Hamid Rassoulian ("the plane of
progression
should always be labelled XY").

The arguments advanced by Barbara van Geems of the University of Cape


Town and based on photogrammetric considerations are also not
convincing. Again, she assumes the recording of a 2D motion executed
in the sagittal plane only, in which case the photographic XY-plane
would coincide with the spatial ISB standard XY-plane. However, in
3D-recording more than one camera are used of which most will be
situated in oblique positions relative to the spatial coordinate
system and certainly not such that the spatial Z-axis always
coincides with the optical axis of the camera concerned. Quite to the


contrary, the optical (z-)axis of a head-mounted camera would be in
line with the ISB-standard-proposed Y-axis.

Finally, the opinion expressed by Dr. J. H. Lawrence III of the
University of Kentucky also (implicitly) assumes ONE plane of
activity ("I believe that the key to maintaining convention when
setting up a 3-D orthogonal measurement system is to establish
Cartesian coordinates in the plane of the activity"). It must be
reiterated that, by definition, 3D-motion analysis and simulation is
not restricted to one plane of activity and, in general, not even to
a
plane of "major activity" that could be clearly identified. Moreover,


such a scheme would again contradict the idea of standardization,
whether desirable or not.

In summary, then, it would appear that the arguments advanced in
support of the proposed ISB convention are not convincing. Also, the
opinion aired by the Editor-in-Chief of the Journal of Biomechanics,
Richard A. Brand, in his EDITORIAL COMMENT on the ISB
recommendations that these represent "a thoughtful approach..." and
"a compilation of commonly accepted practices" may not be shared by
too many biomechanists. In this context it is also noteworthy and
most
remarkable that responses from the members of the ISB Standards and
Terminology Commitee (notably from Ge Wu, Peter Cavanagh, John Paul,
Don Grieve, and others) were conspicuously absent from the present
discussion. The reasons for this strange silence remain clouded in
mystery and forces everyone into speculation.

To conclude, a rejection rate of 79% (in this discussion forum) for
the
proposed ISB convention does not augur well for future acceptance of
these standards. In my opinion, the ISB Standardization and
Terminology Committee would be well advised to withdraw the present
recommendations and revise them in accordance with internationally
accepted conventions and, most important, in collaboration with the
scientific community of biomechanists.

I thank all of you who have contributed to this discussion and
thereby to the clarification of an important issue.

Herbert Hatze, PhD.
Professor of Biomechanics
University of Vienna

Peter Cavanagh
10-15-1995, 02:21 PM
Dear Biomch-L readers:

It has been rewarding to see the discussion over the last two weeks
regarding the ISB Recommendations for Standardization in the Reporting=
of
Kinematic Data. This shows that there is a continued interest in=
this
area, which is why the ISB has moved forward with this project. =
The vigor
of the responses that this topic seems to engender may come as a=
surprise
to some new readers, but I can assure you that this is indeed "par=
for the
course". Any venture into the area of standardization is definitely=
not
for the faint-hearted!

The Recommendation (J. Biomech pp 1257-1260, October 1995) evolved=
through
many versions, and has been developed based on consideration and=
comment
from members of the ISB and from readers of this list. The first=
public
airing of the proposed recommendation was at the XIIIth Congress=
of the
International Society of Biomechanics, December 9-13, 1991, in Perth,
Australia. On behalf of the committee, I presented an outline of=
the
proposed recommendation to approximately 300 ISB members. A lively
discussion ensued and the comments were incorporated into Draft version=
4.0
which was reproduced in the February/March ISB Newsletter #45. BIOMCH-L
readers may want to consult the BIOMCH-L archives for May 4, 1992,=
where
the draft was also posted to all subscribers. Comment was invited=
and a
summary of the comments received was published in the ISB Newsletter=
#47
Aug/Sept 1992. After two further drafts, the recently published
Recommendation emerged. Those of you who missed the earlier posting=
might
find this a good reason (one of many!) to join the ISB in order to=
keep
abreast of these and other current issues.

It is worth noting that a number of other groups such as the Scoliosis
Society, the CAMARC group, the Clinical Gait Analysis Group are also
working on standards and ISB maintains working relationships with=
all of
these groups. There is also a listing under "Standardization" on=
the
Biomechanics Home Page (http://dragon.acadiau.ca/~pbaudin/biomch.html)
which at present points only to ISO. The soon to be released ISB=
home page
will also contain complete details of existing, proposed, and in=
progress
Recommendations and Standards from the ISB.

The debate in the last two weeks has reiterated some of the issues,=
and
reinforced some of the motivations, that led to the pursuit of a=
standard
form of reporting that is specific to Biomechanics:

=80 Within our own field, many different conventions are used for=
reporting
kinematic information so that the reader of each paper has to start=
by
working out which were used by the author (and perhaps holding graphs
upside down or in a mirror!)

=80 Outside our field, we find that there is indeed a number of different
systems for describing the SAME thing. Each of the various sub-disciplines
consider their method to be "standard". =20

=80 We all tend to be very resistant to change from what we have=
used in the
past as "standard".

=80 We have a tendency, if doing more complex analysis, to suggest=
that the
needs of those doing less complex analysis are less important.

=46rom these reasons, the Recommendation was born. A key phrase=
in the title
of the Recommendation is "for the reporting of". The notion here=
is that
no one should have to use a system of computation that they are not
comfortable with or simply do not like. However, once the results=
are to
be communicated to others, then there is a real need for standardization.=
=20
Converting to the ISB axis system could be seen as applying a filter.=
The
input of the filter is specific to each user while the output is
understandable to all. This goes not just for the direction of the
coordinate axes, but also for such things as the conventions used=
for
flexion/extension etc.

The ISB exists for its members, and standardization is something=
that
members have asked us to pursue. No recommendation is cast in stone=
and we
will always move in a direction that the majority of our almost 1000
members are comfortable with. We welcome input from all quarters=
but we
ask you to realize that any decision will leave in its wake a significant
number of disaffected individuals who simply like the way they are=
doing
things at present.=20

As the debate continues, those of you who feel so inclined might=
try using
the ISB conventions in reporting your data. =20


Peter R. Cavanagh
ISB President

M R Yeadon
10-16-1995, 07:36 AM
The following message is the outcome of email discussions on the topic of
standardisation by Fred Yeadon, Ton van den Bogert and Giovanni Legnani.
Since the standardisation proposal is "on the table" interested parties
should (a) accept it as it stands (b) propose changes. We think that changes
are needed and as an initial step have made some comments on the proposal.

Comments on the document:

Standardization and Terminology in Biomechanics.
Volume 1. Section A.
Recommendations for standardization in the reporting of kinematic data.

It should be borne in mind that the purpose of standardisation is to have a
common convention for REPORTING data so that the results of different
researchers can be interpreted and compared more easily. Any discussion on
this document should bear this in mind and avoid issues of what conventions
are best used for data analysis. It is the reporting of results that is the
present focus of the standardisation document.

In the "Recommendations" document:-

Part 1. X, Y, Z axes for displacements

It should be recognised that there IS general agreement on the directions of
the three Cartesian axes in that they are mutually perpendicular, one axis is
vertical, and the directions of the remaining two horizontal axes are not
usually contentious. There is some disagreement as to the NAMING (XYZ) of the
three axes. There is also the issue of the senses of the axes in that there is
general agreement that "up" is positive whereas "left" may be positive or
negative. The system proposed in the standardisation document seems to be
supported by people who have initially used 2D analysis and have added the a
horizontal Z axis for 3D in order to preserve consistency between 2D and 3D.

Unfortunately the majority of researchers in biomechanics seem to favour a
system in which the Z axis is vertical. This does not augur well for the
acceptance of the standardisation proposal in its present form.

However, since there is general agreement on the directions of the axes and the
focus is on the reporting of data, standardisation could take the form of naming
these axes with words rather than with letters. For example, it might be
possible to use "forward", "lateral", and "vertical" to name these directions.
The point is not that particular names be cast in stone but that it become
common practise to use appropriate words rather than XYZ.

Another issue is that the XYZ system used should fit well with the system used
to describe rotations. This will be addressed after the comments on Part 4 and
Part 5.

Part 2. Definition of segmental reference frames

The system proposed in the standardisation document is consistent with the
system proposed for the absolute reference frame in Part 1. However, as noted
above, most researchers are not in agreement with the adoption of the proposed
Part 1. An alternative will be proposed after considering relative orientation
in Part 5.


Part 4. Absolute Orientation

In the standardisation document it is proposed that the absolute orientation of
a body segment be defined by successive rotations about lateral, longitudinal
and frontal axes. Since the system for defining the orientation of the whole
body has not yet been published the present proposal prejudges the issue.
Recommendations have been made to the Standardization Committee on whole body
orientation as detailed in:

Yeadon, M.R. 1990. The simulation of aerial movement. Part I: The determination
of orientation angles from film data. Journal of Biomechanics 23, 59-66.

In this system successive rotations are made about the lateral, frontal and
longitudinal axes. This order of rotations has the advantage that the Cardan
angles of somersault, tilt and twist agree with the nomenclature used by
gymnasts and coaches. Since the focus is on the reporting of data such
considerations of the established use of terminology are of great relevance.

Part 5. Relative Orientation

The description of the system proposed here appears to be somewhat ambiguous but
our interpretation is that successive rotations about lateral, frontal and
longitudinal axes bring one segment from initial alignment with a more proximal
segment to its final relative orientation. That is we interpret the proposal
as stating that the system described in the cited publication (Grood and Sunday,
1983) is to be adopted. If this is so then we are in agreement with this part
of the proposal and expect that most researchers will also find it acceptable.
On the other hand this definition is in conflict with that proposed in Part 4,
suggesting again that Part 4 be changed.

Part 1 and Part 2.

It would be attractive to think that articles could use Tables in which axes
were labelled with words rather than X, Y and Z but since this is unlikely to
occur there is a case for having a standard system. One rationale would be to
let the definition of orientation dictate the axes nomenclature by requiring
sequential rotations about the X, Y and Z axes. This leads to the adoption of
a system with Z vertical (longitudinal).

One final note of caution on the subject of standardisation:

There is a danger if recommendations were to be adopted formally by an academic
journal. Any standardised system will need to be able to adapt to various needs
and changing circumstances. For different types of arm movements it may be
helpful to use different systems of describing orientation. It will not be
helpful if systems are cast in stone from on high. Researchers need the freedom
to choose what they think is best bearing in mind the conventions prevalent at
the time. For example even if whole body orientation is "standardised" in some
way, it should not be imposed on all activity. What is a sensible system for
gymnastics may not necessarily be sensible for high jumping. It should rest
with the researchers of high jumping to arrive at a useful system bearing in
mind what already exists.

Fred Yeadon
Ton van den Bogert
Giovanni Legnani

--
M.R. (Fred) Yeadon
M.R.Yeadon@lut.ac.uk

Peter Cavanagh
10-16-1995, 01:22 PM
The following message was corrupted during a Mac to Eudora transfer.=
Here
is a 'clean' version:

----------------------
Dear Biomch-L readers:

It has been rewarding to see the discussion over the last two weeks
regarding the ISB Recommendations for Standardization in the Reporting=
of
Kinematic Data. This shows that there is a continued interest in=
this
area, which is why the ISB has moved forward with this project. =
The vigor
of the responses that this topic seems to engender may come as a=
surprise
to some new readers, but I can assure you that this is indeed "par=
for the
course". Any venture into the area of standardization is definitely=
not
for the faint-hearted!

The Recommendation (J. Biomech pp 1257-1260, October 1995) evolved=
through
many versions, and has been developed based on consideration and=
comment
from members of the ISB and from readers of this list. The first=
public
airing of the proposed recommendation was at the XIIIth Congress=
of the
International Society of Biomechanics, December 9-13, 1991, in Perth,
Australia. On behalf of the committee, I presented an outline of=
the
proposed recommendation to approximately 300 ISB members. A lively
discussion ensued and the comments were incorporated into Draft version=
4.0
which was reproduced in the February/March ISB Newsletter #45. BIOMCH-L
readers may want to consult the BIOMCH-L archives for May 4, 1992,=
where
the draft was also posted to all subscribers. Comment was invited=
and a
summary of the comments received was published in the ISB Newsletter=
#47
Aug/Sept 1992. After two further drafts, the recently published
Recommendation emerged. Those of you who missed the earlier posting=
might
find this a good reason (one of many!) to join the ISB in order to=
keep
abreast of these and other current issues.

It is worth noting that a number of other groups such as the Scoliosis
Society, the CAMARC group, the Clinical Gait Analysis Group are also
working on standards and ISB maintains working relationships with=
all of
these groups. There is also a listing under "Standardization" on=
the
Biomechanics Home Page (http://dragon.acadiau.ca/~pbaudin/biomch.html)
which at present points only to ISO. The soon to be released ISB=
home page
will also contain complete details of existing, proposed, and in=
progress
Recommendations and Standards from the ISB.

The debate in the last two weeks has reiterated some of the issues,=
and
reinforced some of the motivations, that led to the pursuit of a=
standard
form of reporting that is specific to Biomechanics:

=80 Within our own field, many different conventions are used for=
reporting
kinematic information so that the reader of each paper has to start=
by
working out which were used by the author (and perhaps holding graphs
upside down or in a mirror!)

=80 Outside our field, we find that there is indeed a number of different
systems for describing the SAME thing. Each of the various sub-disciplines
consider their method to be "standard". =20

=80 We all tend to be very resistant to change from what we have=
used in the
past as "standard".

=80 We have a tendency, if doing more complex analysis, to suggest=
that the
needs of those doing less complex analysis are less important.

=46rom these reasons, the Recommendation was born. A key phrase=
in the title
of the Recommendation is "for the reporting of". The notion here=
is that
no one should have to use a system of computation that they are not
comfortable with or simply do not like. However, once the results=
are to
be communicated to others, then there is a real need for standardization.=
=20
Converting to the ISB axis system could be seen as applying a filter.=
The
input of the filter is specific to each user while the output is
understandable to all. This goes not just for the direction of the
coordinate axes, but also for such things as the conventions used=
for
flexion/extension etc.

The ISB exists for its members, and standardization is something=
that
members have asked us to pursue. No recommendation is cast in stone=
and we
will always move in a direction that the majority of our almost 1000
members are comfortable with. We welcome input from all quarters=
but we
ask you to realize that any decision will leave in its wake a significant
number of disaffected individuals who simply like the way they are=
doing
things at present.=20

As the debate continues, those of you who feel so inclined might=
try using
the ISB conventions in reporting your data. =20


Peter R. Cavanagh
ISB President

-----------------





/-------------------------------\
| Peter Cavanagh |
| Center for Locomotion Studies |
| Penn State University |
| University Park |
| PA 16802 USA |
| -x- | =20
| Voice +1 814 865 1972 |
| FAX +1 814 863 4755 |
| Email PRC@PSU.EDU |
\_______________________________/

Jesus Dapena
10-19-1995, 01:15 AM
To the Biomch-L readership:

I agree wholeheartedly with the Yeadon/Bogert/Legnani
counterproposal for standardization.

Comment #1: Cardan angles in the order X-Y-Z (i.e., successive
rotations about the mediolateral, anteroposterior and longitudinal axes)
should be a good and logical way to express segment orientations. I believe
that this should be the "standard", which should be used ***almost***
always. At the same time, we have to keep in mind that such an order (like
any other order) will produce "gimbal lock" at certain orientations. (This
is where some of the angles "go crazy" because there are two very different
combinations of numerical values of the three angles that produce very
similar physical orientations of the segment.) Gimbal lock should be
avoided. A different Cardan angle order will achieve this. That is why I
consider it very important also that the new proposal allows for deviations
from the standard when necessary. There is no angle order that will prevent
gimbal lock everywhere. Any angle order has a "ugly orientation" that
produces gimbal lock. That is why we should not force any given order on
every situation.

Comment #2: I would like to recommend that the X axis generally
should point toward the right, and the Y axis forward, instead of the
alternative (X axis forward and Y axis toward the left). This is not really
a very critical issue, but here is why I think that X toward the right and Y
forward is somewhat better:

When I am analyzing a person walking or running forward, I generally
think of myself as an observer that is traveling with the subject. I feel
that this helps me to gain a more intuitive understanding of what the
subject is experiencing. When I am considering the values of forces or
velocities in the horizontal plane, I think of myself as the subject looking
downward at this plane. Then, if I am using the X=right/Y=forward
convention relative to the direction of motion, when I look at the ground I
will see the positive X direction pointing toward the right and the positive
Y direction pointing forward, which is how I generally draw these axes when
I make any graph on a piece of paper: I am in familiar territory. But if I
use the alternative convention X=forward/Y=left, then when I look at the
ground I see the X direction pointing forward and the Y pointing toward the
left, which is more unfamiliar. I think most people would probably feel
more comfortable with X=right/Y=forward.

Jesus Dapena

H. Hatze
10-22-1995, 09:09 PM
SUBJECT: ISB STANDARDIZATION RECOMMENDATION

The standardization proposals recently made by Yeadon/Bogert/Legnani
(16 October) and endorsed by J. Dapena (19 Oct.), are in full
agreement with my original proposal of 28 September 1995 concerning
the use of Cardan angles to describe 3D whole-body and segment
orientation, and the use of the internationally accepted 3D coordinate
system XYZ. In fact, my three-dimensional 17-segment human body
model first published in 1980 ("A mathematical model for the
computational determination of parameter values of anthropomorphic
segments", J. of Biomechanics 13, 833-843) and then used repeatedly
in subsequent papers ("Neuromusculoskeletal control systems modeling -
a critical survey of recent developments", IEEE Transactions on
Automatic Control AC-25, 375-385, 1980, "HOMSIM: a simulator
of three-dimensional hominoid dynamics", CSIR - Special Report
SWISK 23, 1981, "Computerized optimization of sports motions: an
overview of possibilities, methods and recent developments", J. of
Sports Sciences 1, 3-12, 1983, etc.) already employs Cardan angles
for describing 3D whole-body and segment orientations and, as
spatial and segmental coordinate system, a Cartesian XYZ reference
frame with the X-axis pointing towards the PASSIVE observer (or
to the right of the subject IF THE PLANE OF FORWARD
PROGRthe right of the PASSIVE observer (or in the direction of the
subject moving forward in the sagittal plane), and the Z-axis normal
to the other two axes in a right-handed Cartesian coordinate system.

My reasons for selecting Cardan angles (also called Bryant angles)
were similar to those of Fred Yeadon and Jesus Dapena. While the
critical case (gimbal lock) occurs for Cardan angles at PHI2=PI/2+n*PI
(n=0,1,2,...), this is the case at THETA=n*PI (n=0,1,2,...) for Euler
angles. However, for most situations arising in biomechanics it is
more advantageous to have the critical case occurring at a larger
angle and not near THETA=0. This makes also possible the derivation
of particularly simple expressions for the elements of a Cardan
transformation matrix for the case where all three angles are near
zero, which can not be done if Euler angles are used. This was an
additional reason why I selected Cardan angles.

As far as the XYZ labelling of the spatial and segmental coordinate
axes is concerned, the overriding criterion for me was to adhere
to internationally accepted norms. As already pointed out in my
original e-mail of 28 Sept. 1995, this implies that the XYZ-axes
system described above and also agreed upon by Yeadon, Bogert,
Legnani, Dapena, and many others be used. Exceptions to this
standard should be possible for specific purposes.

I might also mention that I have sent summaries of the present
ISB-standardization e-mail discussions to Dr. R. Brand in his
capacity as editor of the Journal of Biomechanics. I am sure that he
also wants to contribute to the present discussion.

Herbert Hatze, Ph.D.
Professor of Biomechanics, University of Vienna