[ODE] Bounciness

Bryan Thibodeau thibodea at cs.umass.edu
Tue Jul 11 06:27:51 MST 2006

As others have mentioned, ground penetration is a likely culprit.  
Another possibility is not so much the velocity being generated by the 
amotors, but the force being applied at the joints to achieve that 
velocity.  If I recall correctly, an amotor will apply as much force as 
necessary (up to the limit set FMax for that joint, which I think 
defaults to dInfinity) to a joint to achieve the desired velocity in one 
time step.  If you have a very small step size, as you likely would for 
simulating something like bipedal walking, there may be a very large 
impulse force generated initially by the amotor, causing the robot to 
hop.  You could try setting the FMax parameter of the amotor to a 
reasonable value, where reasonable will depend heavily on the type of 
motor and gear box that you assume and the actual velocity of the motor.


Bob Prog wrote:
> Hello,
> I am trying to simulate a walking biped using ODE.  When I set my amotor 
> velocities to try and take a step, the biped immediately hops into the air 
> in a forward motion.  I don't think the velocities I'm applying are so great 
> that it is warranting such a hop.  I would like to just cruise along the 
> ground like a normal walk.  I am not setting the dContactBounce flag in the 
> collision callback, and I'm not using springs.  So what could be causing 
> this?  What am I missing here?  Or is it probably the velocities?
> Thanks,
> Bob
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