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Generating many trajectories and trajectory filter without ShortCutter

asked 2013-03-05 15:32:51 -0500

Ashesh gravatar image

updated 2014-01-28 17:15:32 -0500

ngrennan gravatar image


I am trying to generate diverse set of trajectories for doing a given task (e.g. moving an object from A to B). Currently I am generating such a set of trajectories by changing goal bias of RRT algorithm. All the trajectories obtained using this method have different number of points and hence they should be different. But after passing them through trajectory_filter all the trajectories becomes same and with same number of points.

From what I understand trajectory filter (CubicSplineShortCutterFilterJointTrajectoryWithConstraints) tries to both smoothen and shorten the trajectories. Is it possible to just obtain a smoothen trajectory without any shortening? I can't by-pass trajectory_filter because I also need the time and velocity information.

Moreover, I am not able to get the difference between trajectory_filter and joint_trajectory_generator. It appears to me that both servers almost the same purpose. But I guess joint_trajectory_generator onny smoothens the trajectory and doesn't do any kind of trajectory shortening.

Any help would be appreciated!!!


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answered 2013-03-08 12:38:18 -0500

There are two packages containing a bunch of trajectory filters that you could use: spline_smoother and constraint_aware_spline_smoother. If you look in spline_smoother/default_plugins.xml, you can find a list of plugins that will just fill in timing information without doing any short-cutting. I don't recall the full details of each filter (there are many), but for a start you could try replacing your filter with this one: spline_smoother/CubicSplineVelocityScalerFilterJointTrajectoryWithConstraints.

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Asked: 2013-03-05 15:32:51 -0500

Seen: 650 times

Last updated: Mar 08 '13