Using analogic values

[Fbailly]

Hi all,

I added a Bertec Force sensor to my setup and I am a bit confused with the use of btk. Here is my point : my sensor is a bar of that kind [http://www.erhardt-leimer.fr/cms_media/module_bi/0/243_0_gross_Sensorwalze_PD40.jpg], hence the notion of PWA does not apply, since there is no plane that the central axis of the wrench can intersect with (Shimba 84). Plus, i'm messed up with the frames used by Vicon Nexus for the display, the frame obtained in Matalb and the actual frames of my setup and i'm not confident with the values of moment I obtained... 

I tried to use btkGetGroundReactionWrenches, but since this function gives the wrench at the PWA, I'm afraid it makes no sense. Then I tried to use btkGetForcePlatformWrenches, and I obtained something close to what Vicon displays (with some sign inversion however...). I don't know which sign to believe in, so, unless anyone of you foresees a miracle solution, I'm willing to use directly the analogic chanels to make my own reconstruction. But in that case i'm not sure how to scale, offset and calibrate the data of those chanels. Does anyone know about it, if yes, do you think it is a good idea or are there some restrictions ?

Thanks for the support,

François