[ODE] Kinematic objects

Piotr Obrzut piotr_obrzut at o2.pl
Sun Oct 30 16:25:59 MST 2005


>> 2) Calculate the needed physical parameters (linear velocity, ...) from
>> data given in the kinetic body (mass, ...) and from the velocity (delta
>> of positions)

JS> Hi,
JS> really the step 2 seems a problem. I don't understand it very well, you
JS> should compute needed velocity from given kinematic body mass...? What more
JS> is there where the 3 points in the brackets?
JS> If you want the racket to follow prescribed way and you would simulate it as
JS> a body with normal racket mass, you would have to figure out forces powering
JS> the racket against the ball to move it to desired position during next ODE
JS> step, which I see as a difficult inverse dynamics task (at least in general
JS> case). And I suppose you don't want to model the skeleto-muscular system of
JS> tennis player.

I think he wanted to have object not simulated by physics engine, but
acting on objects inside dynamics system. For that we need to have
physics paramters of kinemtatic driven body at any time of simulation.

I think there are 2 general resolution for that:

1) Use motion function (method described in
http://www.diku.dk/~kenny/thesis.pdf  chapter 3)

2) use last and next position (and time delta between them) of
non-dynamic object to get respective velocity change
(accelaration in result)

 Piotr Obrzut

More information about the ODE mailing list