RMPflow circular movement

Hi guys,

I have been working with Omniverse Isaac for building the path planning of some picking tools with the extensions of single manipulator and RMPflow motion policies plus some picks controllers.

As I was checking the movements it mostly works with linearly. It moves from point A to point B tracing a line (mostly because of the controller and its interpolation between points). I was wondering if there is any possibility to make circulars movements instead of linear movements? Being able to keep controlling the events speeds.

Hi @j.s.p.c. This is often point of confusion with new users of RMPflow. While RMPflow operates directly in joint-space accelerations it is not as low a level of controller as you might expect. It is meant to offer a high level API to solve tasks with multiple objectives (go to target, avoid collision with obstacles, obey joint limits, etc.) that are traditionally tricky to combine into one controller in dynamic environments. Apart from the supported objectives like move-to-target, you cannot get a very fine level of control over what RMPflow is going to do.

You can try setting many way-points along a circular path, but that is simply not the intended use-case and you will end up having to do a fair amount of work spacing your way-points correctly and switching to a new target at the right time to get the behavior you want. But this is the wrong way to use RMPflow.

RMPflow is at its best when you set one target far away and you watch as it figures out how to get there for you. There are of course use-cases where the user wants a specific path to be followed. For this, you should check out the Lula Trajectory Generator which allows you to define task-space paths in a piecewise manner with arcs, lines, and rotations. Since this entails specifying a trajectory exactly, there isn’t room for obstacle avoidance. But if you have a use-case where the world is static and topologically simple, then it is probably the right tool for you.

Hi! I understand now, thank you so much. I see the Lula Trajectory Generator is from the new update, cool. I will test it.

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