# Align x-axis of end effector with vector in space [closed]

Hi all,

I really need your help. I have tried now for a few days to align my end effector with a simple 3d vector in space.
Thats's a quite simple task: given position = x,y,z and given orientation vector = a,b,c but I can't find a function in moveit! to do so. I dont know how to form the geometry_msgs::Pose by position (of course) and **quaternion.** I tried everything like:

- getRPY from current pose
- convert to "vector" (which is of course not equal and simple, lose roll)
- calculate perpendicular vector (cross product) and angle (dot product) between the two vectors above (current+given goal orientation vector)
- from this calculate the quaternion by constructor tf::quaternion(perpendicular vector, angle)

That couldn't be the truth, I must have missed something... please advise. I am using ROS Indigo, Ubuntu 14.04LTS, Moveit!

Thank you very much in advance!

Hannes

Related: #q253361.