[ODE] Scientific modelling of a runner

[Marcus Brubaker]

jnilson_99 at yahoo.com wrote:

>Hi Martin,
>  
>
Close, but no cigar :)

>The both videos represent a visually valid bipedal
>motion. The first is a motion capture sequence, the
>second is based on a motion capture sequence. To this
>I ask, "Has Shakespeares plays been written by
>Shakespeare or a man calling himself Shakespeare?".
>  
>

Huh?  The videos on the linked page are from a paper which infers the 
forces necessary for motion based off of motion capture data.  (It then 
goes on to try to create a model for these forces and uses that to 
create new animations.)  I never claimed they had anything to do with 
understanding walking or other bipedal motion.  It was only mentioned as 
it solved the problem that Martin was asking about.

If you scroll up from that paragraph though, you will however find a 
reference to a natural looking bipedal controller:  the thesis by Jerry 
Pratt.

Regards,
Marcus

>--- Marcus Brubaker <aurelius.marcus at rogers.com>
>wrote:
>
>  
>
>>jnilson_99 at yahoo.com wrote:
>>
>>    
>>
>>>Hi Martin,
>>>
>>>You might want to talk to Jason Malios,
>>>jmallios at cs.brown.edu , who has tried to do a
>>>      
>>>
>>similar
>>    
>>
>>>thing. That is take key frame data and mix it with
>>>physics based inverse kinimetics (ode). Search his
>>>name on the pipermail usergroup for ode.
>>>
>>>As far as your basic question, which is, can a
>>>      
>>>
>>physics
>>    
>>
>>>engine model human movement, well much has been
>>>written about that :-).
>>>
>>>
>>>Forgive me if I suggest you are naive, but you must
>>>understand the considerable difficulty in such
>>>modelling. NO ONE has done it before, otherwise we
>>>would see animotronic humans roaming the earth. Yes
>>>      
>>>
>>a
>>    
>>
>>>few people have simulated bipedal movement, see
>>>      
>>>
>>Russ
>>    
>>
>>>Smith PHD thesis on the Fox Controller. However
>>>      
>>>
>>SMOOTH
>>    
>>
>>>simulation of human bipedal movement is far in the
>>>future I am affraid.
>>>
>>>I only say this in cautioning you to the complexity
>>>      
>>>
>>of
>>    
>>
>>>the problem you seem eager to undertake.
>>> 
>>>
>>>      
>>>
>>Not as far in the future as you think.  See the PhD
>>thesis of Jerry 
>>Pratt from MIT who has successfully created a "2D"
>>walking kneed and 
>>ankled robot and simulated a 3D version, both of
>>which have extremely 
>>natural looking gaits.  Based on some of his ideas,
>>I myself have 
>>created a stochastic walking controller for a 2D
>>kneed biped using ODE 
>>and am currently working to extend it to an ankled
>>model.
>>
>>The problem of determining forces based on mocap
>>data has been recently 
>>published about at SIGGRAPH 2005, see 
>>
>>    
>>
>http://grail.cs.washington.edu/projects/charanim/phys-style.html
>  
>
>> They 
>>use a Lagragian dynamics formulation which allows
>>them to easily infer 
>>the external forces.  I've spoken with one of the
>>authors about this 
>>problem (as it's something I've looked into) and was
>>told that they were 
>>forced to write their own kinematic procecssing of
>>the raw mocap data 
>>because the kinematics output from the Vicon system
>>induced a lot of 
>>noise in the computed forces.  It is not a trivial
>>thing but it has been 
>>done.  However, a simulator like ODE will generally
>>be of no help.
>>
>>Regards,
>>Marcus
>>
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>>    
>>
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