Re: [OpenRAVE-users] understanding CalcTrajTiming

[Rosen D. <ros...@gm...>]

Hi Garrett,

The CalcTrajTiming function computes the timestamps of each of the
waypoints and initializes the internal structures, it does not create
new waypoints. The SampleTrajectory function allows sampling of a new
point given any timestamp.

To answer your question about the max velocities. Currently
CalcTrajTiming takes a fMaxVelMult parameter that allows you to scale
all velocities.

I agree with you that the trajectory class needs a better way to
expose parameters for fine-tuning the various limits, this is
definitely something we need a lot of feedback on.

rosen,

2010/8/30 garratt <ga...@cs...>:
> Hi Rosen,
>
> I'm examining some code in actionlib controller:
>
> in SetDesired():
>
> ptraj->AddPoint(TrajectoryBase::TPOINT(vcurrentvalues,0));
> ptraj->AddPoint(TrajectoryBase::TPOINT(values,0));
> ptraj->CalcTrajTiming(_probot,TrajectoryBase::LINEAR,true,false);
>
> It seems like the purpose of this code is to create a trajectory that
> linearly interpolates in joint space between the current joint position
> and the desired joint position.
>
> However, I notice in TrajectoryBase::_SetLinear()
> that no new points are created.
>
> Is there a way that you intended for points to be created if the robot
> cannot move between the start and the goal within the given
> velocity/acceleration constraints? (also, since we are only adding two
> points in actionlib controller, there is no way that the robot can meet
> it's acceleration constraints)
>
> The observed robot behavior is that it tries to reach the goal position
> at maximum velocity, which is definitely undesirable.
>
> thanks
> Garratt
>
>
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