Revision history [back]

Hi Felix,

Here's the answer to the 2nd part of your question - how does the trajectory filtering work right now?

The trajectory filter takes paths from the planner and "shortcuts" them with cubic splines to try and find a smoother path to the goal. It does this by trying to connect random waypoints on the plan using acceleration and velocity bounded cubic splines. This is why you see the time_from_start change for the waypoints - the trajectory_filter is changing them so that the resultant trajectory obeys velocity and acceleration constraints and is also collision-free.

The reason your arm cannot track these trajectories probably has more to do with your controller. You can decrease the acceleration and velocity limits so you get slower trajectories, here's where those parameters are specified - http://www.ros.org/wiki/trajectory_filters/Tutorials/Tutorial%201#The_joint_limits_specification

The planners are free to give back just paths and leave the time_from_start parameter at 0. OMPL just chooses to specify a nominal time there with the assumption that a post-processing step will take care of the parameterization into a trajectory.