Controlling Pose of a link directly.

asked 2015-11-13 10:43:46 -0600

theNerd247 gravatar image

I'm currently working with a model that has two links with a universal joint connecting the two. I would like to control the model as if a robot were gripping one of the links and moving it around. I don't have a robot model and designing one - or using a pre-existing one - right now is out of the question. Essentially I need to create a fixed link that is ignored by the physics engine and which I can move to any pose at any time in the simulation and it won't move. I've thought about making my link static - although I'm not 100% certain what this does as the SDF documentation says very little about what this tag does - however according to this question:

this is currently not possible. I've tried the following solution:

  1. create 3 links in series like a chain where the first of these links has a fixed joint between it and the world.
  2. Create a prismatic joint between each link in the chain to allow for translational positioning of my model in a plane.
  3. Create a ball joint between the link I want to control and the last link in the chain to enable setting the rotational pose of the link I want to control.

This solution allows me to set the pose of my link however I'm still facing the problem of gravity pulling my model down - that and it seems rather unnecessary. Any ideas?

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