Is there any way to create a parallelogram robot in MoveIt!

asked 2021-04-05 16:26:16 -0500

riverray gravatar image

I am currently working on a robot with an arm made of two connected parallelograms segments. I desperately need a way to control their movement, but I understand closed kinematic loops are not possible in MoveIt! Is there any possible way to represent these two segments in MoveIt! or without mimic joints?

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What's the problem with mimic joints?

fvd gravatar image fvd  ( 2021-04-06 02:20:12 -0500 )edit

I was struggling to get them to function in MoveIt! since closed kinematic loops are not supported in URDF or MoveIt! From what I was reading it looked like I would need to create my own IK for the robot to deal with the loops (instead of using KDL) or find another way to control it other than MoveIt. Today I got it to work relatively well by just not including the mimic joints that would close the loops in the control groups and turning off collisions for them (since they are mostly stationary until the movement is actually executed). However, since the chains that I created still have two mimic joints in them, when I start up MoveIt! I still get the error: Group right_leg has mimic joint, will not initialize dynamics solver. I don't know if this is actually effecting functionality but it otherwise seems to function ...(more)

riverray gravatar image riverray  ( 2021-04-06 17:11:56 -0500 )edit