travel (trajectory) length and time of end-effector joint

[h3ngy1ng]

[rookie] ive a robot arm of 6 joints and would like to know:

1. how does mtc and rviz know joint1 corresponds to the base joint, etc.
2. i have the below code snippet calc the total trajectory length and time but i believe it computes both linear and rotary movement of all 6 joints.
   (x, y, z) from home position to an arbitrary (0, 0.5, 1.5) metres:
   
   

how do i verify mtc and rviz are reading the last joint (joint 6) as end-effector joint and get the travel (trajectory) length, time of specified joint.

[rhaschke]

• how does mtc and rviz know joint1 corresponds to the base joint, etc.

From the URDF, which defines the kinematics as a tree. The root of the tree is the base link / joint.

• i have the below code snippet calc the total trajectory length and time but i believe it computes both linear and rotary movement of all 6 joints.

Indeed this only computes path length in joint space. Have a look at the existing cost functions instead:

• PathLength: joint-space path length
• TrajectoryDuration
• LinkMotion: Cartesian-space path length