Hello! My name is Rene' Ferdinands, and I am currently doing my Masters in

Biomechanical Engineering at the University of Waikato in New Zealand. I

presently hold a Bach. of Electrical Engineering Degree from

R.M.I.T,Australia. My research centres upon optimising the cricket bowling

actionin terms of various biomechanical parameters. Mathematical modelling,

3DVideo and EMG will be used to achieve this end.

At present, I am attempting to model the human body a system of 14 coupled

segments using Lagrangian dynamics. The method used is based on David

A.Winter's technique outlined in 'Biomechanics and Motor Control of Human

Movement (2nd ed.)'and a paper by Onyshko, S. & Winter, D.A. 1980. 'A

Mathematical Model for the Dynamics of Human Locomotion', Journal of

Biomechanics, 13, 361 - 368. So far I have only modelled two segments,which

represent the upper and lower arm as they traverse an orbit about the

shoulder joint, as an attempt to simulate the action of the bowling arm in

cricket. I use numerical techniques to obtain solutions. At this stage, I

am finding difficulty in obtaining practical solutions. The Langrangian

equations are very lengthy, especially when they are converted to a system

of first order D.E's to enable numerical integration.

So I am posing the following for anyone who can help, so that I can review

the approaches of others before me:

(i) Is there any published work that has already modelled the movement of

the human body as a dynamic set of Lagangian equations.

(ii) Alternatively, are there complete models using Newtonian mechanics

force-mass-acceleration-torque).

iii) It would be useful to have an email address for David A. Winter.

(iv) Could I have some references for other types of

mathematical/mechanical models of the human body.

(v) It would be of use to have complete mathematical/mechanical models of

JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

adapted to the cricket bowling action.

(vi) If anyone has personal experience in this area, and can offer some

useful suggestions, please feel free to do so.

Your help is most welcome, and appreciated.

Regards

Rene'

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

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

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

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

From: Derek Kamper

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS

I have used the dynamics package Working Model

to simulate a mulit-segment biomechanical model.

It has a GUI and will compute the dynamics for

you (Newtonian mechanics).

In robotics, Newton-Euler equations are typically

used to solve for forward and inverse dynamics. The

algorithms lend themselves nicely to numerical

solution by computer.

Ex. JJ Craig, Introduction to Robotics. Algorithms

by Luh, Walker,Paul. Good luck.

derek kamper

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

From: Steve Onyshko

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS (fwd)

Hello,

Your e-mail message was forwarded to me. I shall make a few

comments regarding your questions. First, I should say that I worked on

the problem of modeling of human locomotion when I was on sabattical leave

in 1977-78 in Dr.D.A. Winter's locomotion lab at the University of

Waterloo, Waterloo, Onatario, Canada. This resulted in the paper which

appeared in 1980 which you cited in you e-mail. Dr. Winter in now retired,

however, I believe, he is still doing some research at the University of

Waterloo.

As you must be aware, the model I came up with was a seven segment

model in a 2-D plane, ie, there were seven second order DE's or

equivalently, 14 first order DE's.

The problem you're talking about, conceptially, is striaght

forward. However, its extremely messy to work out all the details.

To comment specifically on your points:

(i) Its not clear what you mean by Lagangian equations in that the final

result will be a set of equations of motion which will the same whether you

use the Lagangian approach or Newton's second law.

(ii) There must be, but I haven't been looking into this for a long time now.

(iii) I don't have David A. Winter's e-mail, but you should be able to

get it easily enough by contacting the University of Waterloo.

(iv) I haven't been looking into this lately.

(v) I have no such information.

(vi) This involves very much messy work. Doing it manually is tough

because of the large volume of work you will always make a few errors which

are hard to locate. Using software to manipulate the algebra and calculus

will result in many thousands of lines of code and you will easily get lost

in it.

Goog luck

Steve Onyshko

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

Rene',

I work for a company that makes rigid body dynamics software for

mechanical

design engineering applications. You may want to consider using such

a code for your application. When I did my Ph.D. in biomechanics several

years ago, I derived all my dynamical equations myself using a symbolic

maniputator. While there are some advantages to being able to get your

hands on the actual equations, if you don't need to do this, then a

variety of commercial packages will let you get the job done much

more quickly. Also, these packages usually provide a complete

infrastructure

for numerially integrating the equations, visualizing the motion of the

model, and plotting the results. Some products even have built in

optimization. In any case, for any complex dynamical model, I certainly

would not try to derive the equations by hand, since the chances of

getting the correct equations in the end is pretty low.

Here are some suggestions on commercial products you may want to

consider:

Autolev - a symbolic manipulator for deriving dynamical equations using

Kane's method.

Pros: Relatively easy to derive the equations, equations can be output

to a C or Fortran program which is ready to be numerically

integrated.

The most recent version also has some plotting and visualization

capabilities.

Cons: You need to know Kane's method,and you need to create input text

files to derive the equations.

SD-Fast - a symbolic manipulator for automatically generating equations

of motion from a system description.

Pros: Very easy to derive the equations, an infrastructure is provided

for numerically integrating the equations, and little knowledge of

dynamics is required (you just create an input text file providing a

description of the tree structure of the system and the applied

loads).

Cons: No visualization or plotting capabilities.

Mechanica Motion - commercial grade dynamics package providing a

complete

simulation and optimization environment.

Pros: Little knowledge of dynamics required, you create models with

the

graphical user interface rather than input text files, an implicit

and explicit numerical integrator are built in, optimization is

built

in, and graphing and visualization are provided.

Cons: You can't get your hands on the actual symbolic form of the

equations

(if you need this, e.g., for an analysis you are developing), and

certain

problems (e.g., a planar knee joint where the translations are a

prescribed function of the rotation) cannot be handled.

Hope this information is helpful.

B.J. Fregly

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

Benjamin J. Fregly, Ph.D.

Research and Development Engineer

Pro/MECHANICA MOTION Analysis Technology

Parametric Technology Corporation

2590 North First Street, Suite 200

San Jose, CA 95131

Tel: 408/953-8650

E-mail: bj@sj.ptc.com

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

Dear Rene,

I know from my own experience that dealing with the Lagrangian formulation

may turn out to be a nightmare even for planar systems with low degrees of

freedom (DOF) if you don't know how to approach the problem. If the

system's DOF is high, as it is in your case, manual derivation of the

equations will be useless. You will definitely make small errors like

inappropriate use of +/- signs etc. What I would suggest to you is using a

software that can handle symbolic manupulations such as Mathematica. You

should formulate the kinetic and potential energy terms manually which are

much easier compared to the whole equations of motion. Taking derivatives

and simplifications of the terms are automatically performed by the

symbolic manipulator. Moreover you can save the final equations in text

form and transfer them to your own code by a simple cut and paste

operation. So you don't have to write the final equations again for your

own code.

Using Lagrangian or Newtonian approach depends on what you are looking for.

If you are interested in the forces and moments transmitted through the

joints than Newtonian mechanics will be the best choice (it is also

possible to compute joint forces using Lagrangian mechanics but it is doing

the same job twice). If you decide to use Newtonian mechanics I would

suggest to employ the recursive Newton-Euler formulation which is a

standart application in robotics. If your aim is to make simulations and

you are interested in the simulated joint motions due to applied joint

forces and/or moments then Lagrangian formulation will be appropriate.

If you have further questions I will be glad to answer them.

================================================== =

H. Cenk Guler

Middle East Technical University

Department of Mechanical Engineering

06531 Ankara, Turkey

Tel. : (90) 312 210 5256

Fax : (90) 312 210 1266

E-mail : b092065@orca.cc.metu.edu.tr

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

From: "Paolo de Leva - Sport Biomechanics, Rome, IT"

Dear Rene,

I would suggest you to read, for instance, a paper by Feltner and

Dapena on the mechanics of baseball pitching on the Journal of

biomechanics (I don't have now the exact reference, but you can fin it

easily).

In my personal opinion, you should avoid using Lagrangian mechanics.

I am not familiar with it, but I believe that Newtonian mechanics is

suited for your purpose, as well as Lagrangian mechanics. The advantage

is that the first can be understood by all readers, whilst Lagrangian

mechanics cannot (I'm sure about that; many high level researchers don't

know it, and readers are not supposed to be high level researchers).

If you try and publish your work on a reviewed journal, you might be

asked (I would do it) by the reviewer to show that Newtonian mechanics

was not suited for your purpose, and I bet it would be quite difficult.

This is a basic matter, which is not always considered,

unfortunately: when you have two or more methods to do exactly the same

thing, you shoud use the simplest and most widely known one.

Moreover, Newtonian mechanics is by far simpler and clearer and more

widely known than anything else (including, e.g., Dalembert's approach

based on non-inertial frames and virtual inertial forces/torques, which

is abused in research but rarely taught in undergrad classes).

Paolo

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

From: Ian Fisher

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS

Hi Rene,

This sounds like a very interesting project. One chapter I found very

useful for the sort of thing you're talking about is:

'Euler's & Lagrange's Equations for Linked Rigid Body Models of

Three-Dimesional Human Motion' James G Andrews, p.145 et seq.

in 'Three Dimensional Analysis of Human Movement' Allard, Stokes & Blanchi

(Eds)

Human Kinetics Publishers 1995.

(for more info, look up

http://www.humankinetics.com/product/proddesc/BALL0623.htm)

, I think it's more or less what you are after. A lot of the other

chapters are very good too.

I would have thought a Newtonian approach would be easier - are you

including muscle actions ?

>(v) It would be of use to have complete mathematical/mechanical models of

>JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

>adapted to the cricket bowling action.

(especially if the bowler is a certain Sri Lankan!!)

Have you seen 'Biomechanics of Baseball Pitching' at

http://www.biomech.jhu.edu/projects/bball/bball.html

>(vi) If anyone has personal experience in this area, and can offer some

>useful suggestions, please feel free to do so.

I don't have any experience of working with cricket biomechanics, but I am

interested in cricket & biomechanics and a couple of things occur to me.

(1) I'm sure a lot of insight or valuable model validation could be gained

by looking at which structures normally get injured while bowling and

attempting to draw conclusions (there shouldn't be a shortage of injuries

to study !).

(2) I'm curious as to whether you're planning on modelling the wrist &

finger actions required to spin the ball . One of my mates asked me

whether or not there is any biomechanical reason why you can't bowl fast

with a lot of spin when we were watching a game. I'm pretty sure that the

most important factor is that the action of the entire body is different in

both cases, but we weren't sure whether or not the muscle's force-velocity

relationships would significantly hamper fast hand movements while the arm

is moving quickly.

I'm English, so I know the following is very important in bowling:

(3) Don't be English.

(2) If you are on no account play for the national side.

(1) Don't be Andy Caddick.

Of course, point 3 does not apply if you're Melvyn Betts.

Hope some of the above is useful,

Ian.

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

Dear Rene',

contact Prof. Hatze

University of Vienna, Austria.

Professor of Biomechanics and Head of the Department

He describes his modell in a paper which is on the net.

ISBS '98: http://www.isbs98.uni-konstanz.de/

Select the Geoffrey Dyson Award and you will find the paper.

I hope it helps, good luck

Christian

************************************************** ******

* Dr.Christian Peham

* email: Christian.Peham@vu-wien.ac.at

* Clinic for Orthopaedics in Ungulates

* Locomotion Research Group

* University of Veterinary Medicine Vienna

* Phone: +43-1-250 77/5506; Fax: +43-1-250 77/5590

* Josef Baumanngasse 1; A-1210 Wien

* http://www.vu-wien.ac.at/i111

************************************************** ******

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

You may wnat to seek out the Biomechanics researchers at the Univ of

California, Davis. Many published articles on Baseball and Javolin.

Let me know how I can further help

Motion Analysis Corporation

Daniel India, Vice President

3617 Westwind Blvd

Santa Rosa, CA 95403 USA

HQ Tel: 707-579-6500 Direct 847-945-1411

HQ Fax 707-526-0629 Direct 847-945-1442

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

From: "Glenn Fleisig"

Dear Rene',

While we have not yet looked at the cricket throwing motion, we have

studied baseball, American football, and softball throwing kinematics

and kinetics. Some of the equations are in a few of our articles in the

"Journal of Applied Biomechanics" (Fleisig et al., 1996; Escamilla et

al., 1998; Barrentine et al., 1998). We also wrote a review article in

"Sports Medicine" (Fleisig et al., 1996) that compared and discussed

many different throws, but not cricket.

I hope this is helpful. Feel free to contact me if I can be of further

help.

- Glenn

A SSSS M M IIIIIIII

A A S S MM MM I

A A SS M M M I

AAAAA SS M M I

A A S S M M I

A A SSSS M M IIIIIIII

************************************************** *******

Glenn S. Fleisig, Ph.D.

work phone: 205-918-2138

work fax: 205-918-0800

address: American Sports Medicine Institute

1313 13th Street South

Birmingham, Alabama 35205

web site: http://www.asmi.org

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

From: Rod Whiteley

On 24-Jun-98, Rene Ferdinands wrote:

>Hello! My name is Rene' Ferdinands

G'Day Rene'

>(v) It would be of use to have complete mathematical/mechanical models of

>JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

>adapted to the cricket bowling action.

>(vi) If anyone has personal experience in this area, and can offer some

>useful suggestions, please feel free to do so.

With regard your last two points; I've been interested for a long time in the

mechanics of the throw as they relate to pathology. Being an Australian,

cricket is the summer sport of choice over my beloved baseball, so I've always

been attempting to extrapolate from the well studied and documented act of

baseball pitching to cricket bowling. (Note that there is very little in the

literature on the throws of fielders.) My gut feelinig is that these are very

different activities. The only evidence I can give you for this is a clinical

piece. Throwers with demonstrable shoulder anterior instability are unable to

throw or pitch, but can usually happily bowl. I'd love to stay informed of

your work, and if I can help (with mechanics of pitching references I guess)

let me know.

Rod Whiteley

rwhiteley@magnet.com.au

--

Mitchell & Whiteley Physiotherapy.

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

Rene,

Find attached to this mail a couple of pitcing mechanics references. Once

you've got these, if you chase their reference lists, you'll be well on your

way to the bulk of the throwing literature.

Keep me informed as to your progress regarding bowling, I'd love to be of any

help I can. As I said, I've been thinking about these things for a long time

nw, and may have some ideas of use to you.

Cheers

Rod

--

Mitchell & Whiteley Physiotherapy.

Elliot B., Grove R. Gibson B., Thurston B. A three dimensional

cinematographic analysis of the

fastball and

curveball pitches in baseball. International journal of sport biomechanics

1986 2:20-28

Feltner M., Dapena J. Dynamics of the shoulder and elbow joints of the

throwing arm during a

baseball

pitch. International journal of sport biomechanics 1986 2:235-259

Fleisig G Andrews J Dillman C Escamilla R Kinetics of baseball pitching

with implications about

injury

mechanisms American Journal of Sports Medicine 23 3 1995

Joris, H.J.J., Edwards van Muyen A.J., Van Ingen Schenau J.G., et al Force,

velocity, and energy

flow during

the overarm throw in female handball players. Journal of Biomechanics, 1985

18:409-414

Pappas A.M., Zawacki R.M., Sullivan T.J. Biomechanics of baseball pitching

A preliminary report

The

American Journal of Sports Medicine 13:4, 216-222

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

From: BASTIEN Richard

Hi René

Take a look at http://www.ceit.es/english. They're in Spain near the

french border and have developed a manikin which can simulate movement

based on a motion capture system. The calculation gives you torques,

acceleration etc.

You can also take a look at http://www.transom.com, they're retailing

JackTM software which has been developed by Norm Badler (Univ of

Pennsylvania, Philly), this manikin has a inverse kinematic engine that

might give you some ideas.

You can also take a look at

http://www.adams.com/mdi/product/modules/android.htm. They've got a

manikin that is used by some R&D lab in sports. They have a good

background in sport simulation, even if this isn't written in their web

site. I have the name of the development manager in LA if you're

interested.

Hope this helps

Richard

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

From: Wolfgang Pagani

Reply-To: pagani@writeme.com

Dear Rene Ferdinands,

if you want to do any 3D modeling try a software that is called SIMI Motion or

SIMI Motion Capture. With those two packages you are able to digitize any kind

of motion and make your own virtuell charackters move like real ones. Or you

just want to analyze motion e.g. velocity(left foot right foot)

angles(hip-knee-ankle).... 3D view...

For more information go to http://www.simi.net

Yours sincerely

Wolfgang Pagani

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

From: Dwight Meglan

Subject: Dynamics of movement

Hi Rene,

It wasn't clear to me if you are doing inverse or forward dynamics, i.e.

analyzing the forces/torques at the joints based on captured data or if you

are synthesizing motions from prescribed forces/torques. For Inverse

dynamics there a number commercial packages around (check the biomechanics

website) and there is a public domain package that I wrote a number of

years ago (also at the website). For forward dyanmic simulations, there are

also a number commercial packages, such as ADAMS/Android (Mechanical

Dynamics) and SIMM/Dynamics Pipeline (MusculoGraphics) which are just for

human figure simulation. In addition, I did my own forward dynamics package

for for my PhD years ago-- I wouldn't use though, too many unfinished

pieces and a fuzzy mind on my part relative to support ;-) There have been

a number of research works on figure simulation in recent years, e.g.

Michael McKenna of MIT. Also, I know at least one free package for

multibody dynamics called dynamechs out of the naval postgraduate school --

don't have the web address but I am sure you can dig it up. Lastly, I

recently saw a demo from a company called Katrix which had a dynamic

simulation of a human figure. It was a 2.5D simulation (partial right-left

balance) with maybe 12-17 DOF but it ran at 30 Hz on a PC -- they are

working on this to add better motion to characters in games and dismounted

infantry for military simulations. Boston Dynamics also sells a product for

dismounted infantry, DI/Guy.

Do some digging on the web you'll find all kinds of stuff -- have fun ;-)

--dwight

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

From: Tom Buchanan

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS

Rene'

I suggest you look at the software being developed by Ali Seireg at U

Wisconsin (http://www.engr.wisc.edu/me/faculty/seireg_ali.html). It models

many, many body segments. It is scheduled to be released very soon, along

with a series of textbooks describing how to use it.

tsb

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

From: "Harald Böhm"

Organization: Deutsche Sporthochschule Köln

X-Mailer: Mozilla 4.03 [de] (WinNT; I)

To: redf1@waikato.ac.nz

Subject: Re: Lagrange Mechanics

Hallo Rene

> (i) Is there any published work that has already modelled the movement of

> the human body as a dynamic set of Lagangian equations.

In the book: E.J. haug: 'Computer -Aided Kinematics and Dynamics of mechanical

Systems'Allyn and Bacon Boston,

They describe how to write the Equations of motion with the help of Lagrange

Multipliers.

It is not directly for the human Body but they explain Joints and everything

you need to build

a human Body.

> (ii) Alternatively, are there complete models using Newtonian mechanics

> (force-mass-acceleration-torque).

> (iii) It would be useful to have an email address for David A. Winter.

> (iv) Could I have some references for other types of

> mathematical/mechanical models of the human body.

> (v) It would be of use to have complete mathematical/mechanical models of

> JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

> adapted to the cricket bowling action.

> (vi) If anyone has personal experience in this area, and can offer some

> useful suggestions, please feel free to do so.

I have some experience in modeling Human Multibody Systems but I've formulated

the equation of motion only for 2D. by myself. In 3D. the Equations are too

long and too much so that I am using a multibody software such as ALASKA,

DADS, SIMPACK... (This software is quite expensive.)

In the software DADS they are using Euler Parameters for describing the

rotations to avoid singularities in their matrices. maybe this could help you

to obtain better solutions.

>

Maybe this Information helps a little

So long

Harald

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

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

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

Biomechanical Engineering at the University of Waikato in New Zealand. I

presently hold a Bach. of Electrical Engineering Degree from

R.M.I.T,Australia. My research centres upon optimising the cricket bowling

actionin terms of various biomechanical parameters. Mathematical modelling,

3DVideo and EMG will be used to achieve this end.

At present, I am attempting to model the human body a system of 14 coupled

segments using Lagrangian dynamics. The method used is based on David

A.Winter's technique outlined in 'Biomechanics and Motor Control of Human

Movement (2nd ed.)'and a paper by Onyshko, S. & Winter, D.A. 1980. 'A

Mathematical Model for the Dynamics of Human Locomotion', Journal of

Biomechanics, 13, 361 - 368. So far I have only modelled two segments,which

represent the upper and lower arm as they traverse an orbit about the

shoulder joint, as an attempt to simulate the action of the bowling arm in

cricket. I use numerical techniques to obtain solutions. At this stage, I

am finding difficulty in obtaining practical solutions. The Langrangian

equations are very lengthy, especially when they are converted to a system

of first order D.E's to enable numerical integration.

So I am posing the following for anyone who can help, so that I can review

the approaches of others before me:

(i) Is there any published work that has already modelled the movement of

the human body as a dynamic set of Lagangian equations.

(ii) Alternatively, are there complete models using Newtonian mechanics

force-mass-acceleration-torque).

iii) It would be useful to have an email address for David A. Winter.

(iv) Could I have some references for other types of

mathematical/mechanical models of the human body.

(v) It would be of use to have complete mathematical/mechanical models of

JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

adapted to the cricket bowling action.

(vi) If anyone has personal experience in this area, and can offer some

useful suggestions, please feel free to do so.

Your help is most welcome, and appreciated.

Regards

Rene'

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

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

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

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

From: Derek Kamper

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS

I have used the dynamics package Working Model

to simulate a mulit-segment biomechanical model.

It has a GUI and will compute the dynamics for

you (Newtonian mechanics).

In robotics, Newton-Euler equations are typically

used to solve for forward and inverse dynamics. The

algorithms lend themselves nicely to numerical

solution by computer.

Ex. JJ Craig, Introduction to Robotics. Algorithms

by Luh, Walker,Paul. Good luck.

derek kamper

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

From: Steve Onyshko

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS (fwd)

Hello,

Your e-mail message was forwarded to me. I shall make a few

comments regarding your questions. First, I should say that I worked on

the problem of modeling of human locomotion when I was on sabattical leave

in 1977-78 in Dr.D.A. Winter's locomotion lab at the University of

Waterloo, Waterloo, Onatario, Canada. This resulted in the paper which

appeared in 1980 which you cited in you e-mail. Dr. Winter in now retired,

however, I believe, he is still doing some research at the University of

Waterloo.

As you must be aware, the model I came up with was a seven segment

model in a 2-D plane, ie, there were seven second order DE's or

equivalently, 14 first order DE's.

The problem you're talking about, conceptially, is striaght

forward. However, its extremely messy to work out all the details.

To comment specifically on your points:

(i) Its not clear what you mean by Lagangian equations in that the final

result will be a set of equations of motion which will the same whether you

use the Lagangian approach or Newton's second law.

(ii) There must be, but I haven't been looking into this for a long time now.

(iii) I don't have David A. Winter's e-mail, but you should be able to

get it easily enough by contacting the University of Waterloo.

(iv) I haven't been looking into this lately.

(v) I have no such information.

(vi) This involves very much messy work. Doing it manually is tough

because of the large volume of work you will always make a few errors which

are hard to locate. Using software to manipulate the algebra and calculus

will result in many thousands of lines of code and you will easily get lost

in it.

Goog luck

Steve Onyshko

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

Rene',

I work for a company that makes rigid body dynamics software for

mechanical

design engineering applications. You may want to consider using such

a code for your application. When I did my Ph.D. in biomechanics several

years ago, I derived all my dynamical equations myself using a symbolic

maniputator. While there are some advantages to being able to get your

hands on the actual equations, if you don't need to do this, then a

variety of commercial packages will let you get the job done much

more quickly. Also, these packages usually provide a complete

infrastructure

for numerially integrating the equations, visualizing the motion of the

model, and plotting the results. Some products even have built in

optimization. In any case, for any complex dynamical model, I certainly

would not try to derive the equations by hand, since the chances of

getting the correct equations in the end is pretty low.

Here are some suggestions on commercial products you may want to

consider:

Autolev - a symbolic manipulator for deriving dynamical equations using

Kane's method.

Pros: Relatively easy to derive the equations, equations can be output

to a C or Fortran program which is ready to be numerically

integrated.

The most recent version also has some plotting and visualization

capabilities.

Cons: You need to know Kane's method,and you need to create input text

files to derive the equations.

SD-Fast - a symbolic manipulator for automatically generating equations

of motion from a system description.

Pros: Very easy to derive the equations, an infrastructure is provided

for numerically integrating the equations, and little knowledge of

dynamics is required (you just create an input text file providing a

description of the tree structure of the system and the applied

loads).

Cons: No visualization or plotting capabilities.

Mechanica Motion - commercial grade dynamics package providing a

complete

simulation and optimization environment.

Pros: Little knowledge of dynamics required, you create models with

the

graphical user interface rather than input text files, an implicit

and explicit numerical integrator are built in, optimization is

built

in, and graphing and visualization are provided.

Cons: You can't get your hands on the actual symbolic form of the

equations

(if you need this, e.g., for an analysis you are developing), and

certain

problems (e.g., a planar knee joint where the translations are a

prescribed function of the rotation) cannot be handled.

Hope this information is helpful.

B.J. Fregly

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

Benjamin J. Fregly, Ph.D.

Research and Development Engineer

Pro/MECHANICA MOTION Analysis Technology

Parametric Technology Corporation

2590 North First Street, Suite 200

San Jose, CA 95131

Tel: 408/953-8650

E-mail: bj@sj.ptc.com

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Dear Rene,

I know from my own experience that dealing with the Lagrangian formulation

may turn out to be a nightmare even for planar systems with low degrees of

freedom (DOF) if you don't know how to approach the problem. If the

system's DOF is high, as it is in your case, manual derivation of the

equations will be useless. You will definitely make small errors like

inappropriate use of +/- signs etc. What I would suggest to you is using a

software that can handle symbolic manupulations such as Mathematica. You

should formulate the kinetic and potential energy terms manually which are

much easier compared to the whole equations of motion. Taking derivatives

and simplifications of the terms are automatically performed by the

symbolic manipulator. Moreover you can save the final equations in text

form and transfer them to your own code by a simple cut and paste

operation. So you don't have to write the final equations again for your

own code.

Using Lagrangian or Newtonian approach depends on what you are looking for.

If you are interested in the forces and moments transmitted through the

joints than Newtonian mechanics will be the best choice (it is also

possible to compute joint forces using Lagrangian mechanics but it is doing

the same job twice). If you decide to use Newtonian mechanics I would

suggest to employ the recursive Newton-Euler formulation which is a

standart application in robotics. If your aim is to make simulations and

you are interested in the simulated joint motions due to applied joint

forces and/or moments then Lagrangian formulation will be appropriate.

If you have further questions I will be glad to answer them.

================================================== =

H. Cenk Guler

Middle East Technical University

Department of Mechanical Engineering

06531 Ankara, Turkey

Tel. : (90) 312 210 5256

Fax : (90) 312 210 1266

E-mail : b092065@orca.cc.metu.edu.tr

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From: "Paolo de Leva - Sport Biomechanics, Rome, IT"

Dear Rene,

I would suggest you to read, for instance, a paper by Feltner and

Dapena on the mechanics of baseball pitching on the Journal of

biomechanics (I don't have now the exact reference, but you can fin it

easily).

In my personal opinion, you should avoid using Lagrangian mechanics.

I am not familiar with it, but I believe that Newtonian mechanics is

suited for your purpose, as well as Lagrangian mechanics. The advantage

is that the first can be understood by all readers, whilst Lagrangian

mechanics cannot (I'm sure about that; many high level researchers don't

know it, and readers are not supposed to be high level researchers).

If you try and publish your work on a reviewed journal, you might be

asked (I would do it) by the reviewer to show that Newtonian mechanics

was not suited for your purpose, and I bet it would be quite difficult.

This is a basic matter, which is not always considered,

unfortunately: when you have two or more methods to do exactly the same

thing, you shoud use the simplest and most widely known one.

Moreover, Newtonian mechanics is by far simpler and clearer and more

widely known than anything else (including, e.g., Dalembert's approach

based on non-inertial frames and virtual inertial forces/torques, which

is abused in research but rarely taught in undergrad classes).

Paolo

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

From: Ian Fisher

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS

Hi Rene,

This sounds like a very interesting project. One chapter I found very

useful for the sort of thing you're talking about is:

'Euler's & Lagrange's Equations for Linked Rigid Body Models of

Three-Dimesional Human Motion' James G Andrews, p.145 et seq.

in 'Three Dimensional Analysis of Human Movement' Allard, Stokes & Blanchi

(Eds)

Human Kinetics Publishers 1995.

(for more info, look up

http://www.humankinetics.com/product/proddesc/BALL0623.htm)

, I think it's more or less what you are after. A lot of the other

chapters are very good too.

I would have thought a Newtonian approach would be easier - are you

including muscle actions ?

>(v) It would be of use to have complete mathematical/mechanical models of

>JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

>adapted to the cricket bowling action.

(especially if the bowler is a certain Sri Lankan!!)

Have you seen 'Biomechanics of Baseball Pitching' at

http://www.biomech.jhu.edu/projects/bball/bball.html

>(vi) If anyone has personal experience in this area, and can offer some

>useful suggestions, please feel free to do so.

I don't have any experience of working with cricket biomechanics, but I am

interested in cricket & biomechanics and a couple of things occur to me.

(1) I'm sure a lot of insight or valuable model validation could be gained

by looking at which structures normally get injured while bowling and

attempting to draw conclusions (there shouldn't be a shortage of injuries

to study !).

(2) I'm curious as to whether you're planning on modelling the wrist &

finger actions required to spin the ball . One of my mates asked me

whether or not there is any biomechanical reason why you can't bowl fast

with a lot of spin when we were watching a game. I'm pretty sure that the

most important factor is that the action of the entire body is different in

both cases, but we weren't sure whether or not the muscle's force-velocity

relationships would significantly hamper fast hand movements while the arm

is moving quickly.

I'm English, so I know the following is very important in bowling:

(3) Don't be English.

(2) If you are on no account play for the national side.

(1) Don't be Andy Caddick.

Of course, point 3 does not apply if you're Melvyn Betts.

Hope some of the above is useful,

Ian.

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

Dear Rene',

contact Prof. Hatze

University of Vienna, Austria.

Professor of Biomechanics and Head of the Department

He describes his modell in a paper which is on the net.

ISBS '98: http://www.isbs98.uni-konstanz.de/

Select the Geoffrey Dyson Award and you will find the paper.

I hope it helps, good luck

Christian

************************************************** ******

* Dr.Christian Peham

* email: Christian.Peham@vu-wien.ac.at

* Clinic for Orthopaedics in Ungulates

* Locomotion Research Group

* University of Veterinary Medicine Vienna

* Phone: +43-1-250 77/5506; Fax: +43-1-250 77/5590

* Josef Baumanngasse 1; A-1210 Wien

* http://www.vu-wien.ac.at/i111

************************************************** ******

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

You may wnat to seek out the Biomechanics researchers at the Univ of

California, Davis. Many published articles on Baseball and Javolin.

Let me know how I can further help

Motion Analysis Corporation

Daniel India, Vice President

3617 Westwind Blvd

Santa Rosa, CA 95403 USA

HQ Tel: 707-579-6500 Direct 847-945-1411

HQ Fax 707-526-0629 Direct 847-945-1442

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

From: "Glenn Fleisig"

Dear Rene',

While we have not yet looked at the cricket throwing motion, we have

studied baseball, American football, and softball throwing kinematics

and kinetics. Some of the equations are in a few of our articles in the

"Journal of Applied Biomechanics" (Fleisig et al., 1996; Escamilla et

al., 1998; Barrentine et al., 1998). We also wrote a review article in

"Sports Medicine" (Fleisig et al., 1996) that compared and discussed

many different throws, but not cricket.

I hope this is helpful. Feel free to contact me if I can be of further

help.

- Glenn

A SSSS M M IIIIIIII

A A S S MM MM I

A A SS M M M I

AAAAA SS M M I

A A S S M M I

A A SSSS M M IIIIIIII

************************************************** *******

Glenn S. Fleisig, Ph.D.

work phone: 205-918-2138

work fax: 205-918-0800

address: American Sports Medicine Institute

1313 13th Street South

Birmingham, Alabama 35205

web site: http://www.asmi.org

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

From: Rod Whiteley

On 24-Jun-98, Rene Ferdinands wrote:

>Hello! My name is Rene' Ferdinands

G'Day Rene'

>(v) It would be of use to have complete mathematical/mechanical models of

>JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

>adapted to the cricket bowling action.

>(vi) If anyone has personal experience in this area, and can offer some

>useful suggestions, please feel free to do so.

With regard your last two points; I've been interested for a long time in the

mechanics of the throw as they relate to pathology. Being an Australian,

cricket is the summer sport of choice over my beloved baseball, so I've always

been attempting to extrapolate from the well studied and documented act of

baseball pitching to cricket bowling. (Note that there is very little in the

literature on the throws of fielders.) My gut feelinig is that these are very

different activities. The only evidence I can give you for this is a clinical

piece. Throwers with demonstrable shoulder anterior instability are unable to

throw or pitch, but can usually happily bowl. I'd love to stay informed of

your work, and if I can help (with mechanics of pitching references I guess)

let me know.

Rod Whiteley

rwhiteley@magnet.com.au

--

Mitchell & Whiteley Physiotherapy.

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

Rene,

Find attached to this mail a couple of pitcing mechanics references. Once

you've got these, if you chase their reference lists, you'll be well on your

way to the bulk of the throwing literature.

Keep me informed as to your progress regarding bowling, I'd love to be of any

help I can. As I said, I've been thinking about these things for a long time

nw, and may have some ideas of use to you.

Cheers

Rod

--

Mitchell & Whiteley Physiotherapy.

Elliot B., Grove R. Gibson B., Thurston B. A three dimensional

cinematographic analysis of the

fastball and

curveball pitches in baseball. International journal of sport biomechanics

1986 2:20-28

Feltner M., Dapena J. Dynamics of the shoulder and elbow joints of the

throwing arm during a

baseball

pitch. International journal of sport biomechanics 1986 2:235-259

Fleisig G Andrews J Dillman C Escamilla R Kinetics of baseball pitching

with implications about

injury

mechanisms American Journal of Sports Medicine 23 3 1995

Joris, H.J.J., Edwards van Muyen A.J., Van Ingen Schenau J.G., et al Force,

velocity, and energy

flow during

the overarm throw in female handball players. Journal of Biomechanics, 1985

18:409-414

Pappas A.M., Zawacki R.M., Sullivan T.J. Biomechanics of baseball pitching

A preliminary report

The

American Journal of Sports Medicine 13:4, 216-222

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

From: BASTIEN Richard

Hi René

Take a look at http://www.ceit.es/english. They're in Spain near the

french border and have developed a manikin which can simulate movement

based on a motion capture system. The calculation gives you torques,

acceleration etc.

You can also take a look at http://www.transom.com, they're retailing

JackTM software which has been developed by Norm Badler (Univ of

Pennsylvania, Philly), this manikin has a inverse kinematic engine that

might give you some ideas.

You can also take a look at

http://www.adams.com/mdi/product/modules/android.htm. They've got a

manikin that is used by some R&D lab in sports. They have a good

background in sport simulation, even if this isn't written in their web

site. I have the name of the development manager in LA if you're

interested.

Hope this helps

Richard

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

From: Wolfgang Pagani

Reply-To: pagani@writeme.com

Dear Rene Ferdinands,

if you want to do any 3D modeling try a software that is called SIMI Motion or

SIMI Motion Capture. With those two packages you are able to digitize any kind

of motion and make your own virtuell charackters move like real ones. Or you

just want to analyze motion e.g. velocity(left foot right foot)

angles(hip-knee-ankle).... 3D view...

For more information go to http://www.simi.net

Yours sincerely

Wolfgang Pagani

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

From: Dwight Meglan

Subject: Dynamics of movement

Hi Rene,

It wasn't clear to me if you are doing inverse or forward dynamics, i.e.

analyzing the forces/torques at the joints based on captured data or if you

are synthesizing motions from prescribed forces/torques. For Inverse

dynamics there a number commercial packages around (check the biomechanics

website) and there is a public domain package that I wrote a number of

years ago (also at the website). For forward dyanmic simulations, there are

also a number commercial packages, such as ADAMS/Android (Mechanical

Dynamics) and SIMM/Dynamics Pipeline (MusculoGraphics) which are just for

human figure simulation. In addition, I did my own forward dynamics package

for for my PhD years ago-- I wouldn't use though, too many unfinished

pieces and a fuzzy mind on my part relative to support ;-) There have been

a number of research works on figure simulation in recent years, e.g.

Michael McKenna of MIT. Also, I know at least one free package for

multibody dynamics called dynamechs out of the naval postgraduate school --

don't have the web address but I am sure you can dig it up. Lastly, I

recently saw a demo from a company called Katrix which had a dynamic

simulation of a human figure. It was a 2.5D simulation (partial right-left

balance) with maybe 12-17 DOF but it ran at 30 Hz on a PC -- they are

working on this to add better motion to characters in games and dismounted

infantry for military simulations. Boston Dynamics also sells a product for

dismounted infantry, DI/Guy.

Do some digging on the web you'll find all kinds of stuff -- have fun ;-)

--dwight

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

From: Tom Buchanan

Subject: Re: RIGID BODY MODELLING WITH LANGRANGIAN MECHANICS

Rene'

I suggest you look at the software being developed by Ali Seireg at U

Wisconsin (http://www.engr.wisc.edu/me/faculty/seireg_ali.html). It models

many, many body segments. It is scheduled to be released very soon, along

with a series of textbooks describing how to use it.

tsb

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

From: "Harald Böhm"

Organization: Deutsche Sporthochschule Köln

X-Mailer: Mozilla 4.03 [de] (WinNT; I)

To: redf1@waikato.ac.nz

Subject: Re: Lagrange Mechanics

Hallo Rene

> (i) Is there any published work that has already modelled the movement of

> the human body as a dynamic set of Lagangian equations.

In the book: E.J. haug: 'Computer -Aided Kinematics and Dynamics of mechanical

Systems'Allyn and Bacon Boston,

They describe how to write the Equations of motion with the help of Lagrange

Multipliers.

It is not directly for the human Body but they explain Joints and everything

you need to build

a human Body.

> (ii) Alternatively, are there complete models using Newtonian mechanics

> (force-mass-acceleration-torque).

> (iii) It would be useful to have an email address for David A. Winter.

> (iv) Could I have some references for other types of

> mathematical/mechanical models of the human body.

> (v) It would be of use to have complete mathematical/mechanical models of

> JAVELIN/THROWING/BASEBALL PITCHING because this can be most suitably

> adapted to the cricket bowling action.

> (vi) If anyone has personal experience in this area, and can offer some

> useful suggestions, please feel free to do so.

I have some experience in modeling Human Multibody Systems but I've formulated

the equation of motion only for 2D. by myself. In 3D. the Equations are too

long and too much so that I am using a multibody software such as ALASKA,

DADS, SIMPACK... (This software is quite expensive.)

In the software DADS they are using Euler Parameters for describing the

rotations to avoid singularities in their matrices. maybe this could help you

to obtain better solutions.

>

Maybe this Information helps a little

So long

Harald

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