small cartesian motion results in +/- pi joint errors

asked 2021-11-16 14:23:18 -0500

jhwee gravatar image

Distro: Noetic OS: Ubuntu 20.04


I am using the moveit robot commander to move my robot (Interbotix VX300S, 6dof) in 1cm increments based on a keyboard input. ex. "Press A and move left 1cm". The moveit cartesian plan for moving between these two positions often contains two waypoints and a corresponding set of planned joint positions. When the trajectory is actually executed, the commanded joint positions are incorrect by +/- pi from the planned waypoint joint positions (causing a complete joint flip) but the resulting ee cartesian position is correct. These joint flips are inconsistently happening as well. I've attempted moving between the same position multiple times and occasionally this +/- pi joint error occurs. The robot is not operating near it's joint limits when this is happening.

I am using the geometric::RRTConnect path planner and have tried LMA, KDL and Trac IK kinematics.

Thank you

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