[ODE] Torque settings for simulated servo

[Proy. Grado Construccion de Robots Bipedos - ENS]

Hello,

    I think your mistake is with the constant "g". Supose you use grams 
for mass, is "g" still 98,1 ? I think not. My guess is that with your 
units g=981, so when you multiply by 1 unit of mass you get 981 
dm.hg/s^2  (dm=decimeter, hg=hectogram). I hope that helps. Why don't 
you use a standar system ? I use SI.

Regards,
    Damián Lezama
    Proyecto de Grado - Construcción de Robots Bípedos
    http://www.fing.edu.uy/~pgrobip

Garvin Haslett wrote:

>I am using ODE to simulate a robot that I am building.  To model the 
>servo motors I am using hinges but I seem to be making an error in 
>setting the servo torque.  I have set gravity to -98.1, thus implying 
>that one unit of distance is 10cm.  I have chosen my unit of mass to 
>be 0.1 kg.
>
>The data sheet for my servo lists the torque as being 4.1 kg cm or 
>0.041 kg m.  I convert this to Nm by multiplying by 9.81 giving 0.402 
>Nm.
>
>I seem to be getting lost in choosing the correct unit of torque in 
>simulation.  I've taken the view that a real Newton is the kgm/s^2 so 
>therefore one of my simulated "Newton" shoud be 0.01 N (0.1m x 
>0.1kg).  Continuing this logic my unit for torque should be 0.001Nm so 
>my the value I set the Max Torque for my servo should be 402.
>
>However once I do this I find my simulated servo lifting weights the 
>real one cannot.
>
>Is there any obvious flaw in my reasoning here?
>
>Thanks in anticipation of any help,
>
>Garvin.
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