# About the Cartesian trajectory controllers and Movegroup **URL:** \ **Category:** ROS\ **Created:** [January 12, 2022, 7:12am UTC](https://forum.universal-robots.com/t/about-the-cartesian-trajectory-controllers-and-movegroup/18606 "2022-01-12T07:12:13Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![along893](https://avatars.discourse-cdn.com/v4/letter/a/cab0a1/32.png) [@along893](https://forum.universal-robots.com/u/along893)\ **Post date:** [January 12, 2022, 7:12am UTC](https://forum.universal-robots.com/t/about-the-cartesian-trajectory-controllers-and-movegroup/18606/1 "2022-01-12T07:12:13Z")
[Cartesian Trajectory Controllers] Hi, I have 2 questions. I’m using UR10 CB3 and CARTESIAN\_TRAJECTORY\_CONTROLLERS =[“pose\_based\_cartesian\_traj\_controller”] with ros actionlib. It works well. I wrote a python program referring to “Universal\_Robots\_ROS\_Driver/ur\_robot\_driver/scripts/test\_move.py” below. [https://github.com/UniversalRobots/Universal\_Robots\_ROS\_Driver/blob/master/ur\_robot\_driver/scripts/test\_move](https://github.com/UniversalRobots/Universal_Robots_ROS_Driver/blob/master/ur_robot_driver/scripts/test_move) I believe “base\_link” of the UR10 arm is origin of the coordinate system. So, when I commanded to go x=0.5, y=0.0, z=0.6, ee\_link goes +0.5m along the X axis and +0.6m along the Z axis from the origin of base\_link(0,0,0). At this point, the origin of ee\_link moves certain distance from the origin of base\_link. _ **1. However, I wanna make ee\_link move based on its own origin of ee\_link. Is there any way or controller to do this?** _ (Because the xyz axis direction of base\_link is not the same as ee\_link) [MoveGroup] Here’s the another question about MoveGroup. When I commanded CARTESIAN\_TRAJECTORY\_CONTROLLERS =[“pose\_based\_cartesian\_traj\_controller”], the results of get\_current\_pose function are not matched. position.z are the same, but position.x y and orientation are different each other as you see below (Command pose and Robot moved) ![Screenshot from 2022-01-12 16-04-07](https://us1.discourse-cdn.com/flex020/uploads/universal_robots/original/2X/d/d9be5829a8e73f93ffee8a3e6d3409b4bbe94c8a.png) (get\_current\_pose(“ee\_link”) after Robot stoped) ![Screenshot from 2022-01-12 16-06-02](https://us1.discourse-cdn.com/flex020/uploads/universal_robots/original/2X/3/3f163eb78a32e364f8e43ab303cc2c1c0d2d2ea2.png) _ **2. To match them, Which part should check first?** _ Thank you. ---
**Author:** ![mauch](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@mauch](https://forum.universal-robots.com/u/mauch)\ **Post date:** [January 14, 2022, 3:44pm UTC](https://forum.universal-robots.com/t/about-the-cartesian-trajectory-controllers-and-movegroup/18606/2 "2022-01-14T15:44:51Z")
Regarding your first question: Poses are currently expected to be in `base`. You can transform a pose from `ee_link` to `base` using ROS tf system and then send that to the controller. However, I think that this should be handled by the controller, please see my corresponding [issue](https://github.com/UniversalRobots/Universal_Robots_ROS_controllers_cartesian/issues/11). Regarding your second question: Keep in mind, that `base` and `base_link` are not the same. While the controller “thinks” in `base`, the move group might have `base_link` as reference system. As the transformation between them is a rotation by 180 degree, `x` and `y` values are negated. ---
**Author:** ![along893](https://avatars.discourse-cdn.com/v4/letter/a/cab0a1/32.png) [@along893](https://forum.universal-robots.com/u/along893)\ **Post date:** [January 20, 2022, 6:10am UTC](https://forum.universal-robots.com/t/about-the-cartesian-trajectory-controllers-and-movegroup/18606/3 "2022-01-20T06:10:14Z")
Thanks for the reply in detail. I’m still understanding and googling in regard to what you mentioned and your corresponding issue. To sum up - Can transform from ‘ee\_link’ to ‘base’ - Changing the frame of the poses in cartesian trajectory controller hasn’t implemented yet, as seen the issue - Yes u’r right. I commanded cartesian trajectory controller and read the ee\_link pose using movegroup And I’m still trying to understand the issue and your mention below. Could you give a little move detail? > [@mauch](#): > > However, I think that this should be handled by the controller [New questions] 3. If possible, how can I to get the robot current pose based on ‘base’ reference frame using movegroup? I actually tried this using ‘[setPoseReferenceFrame](http://docs.ros.org/en/jade/api/moveit_ros_planning_interface/html/classmoveit_1_1planning__interface_1_1MoveGroup.html#a6a45099e51a06c7cac30e75954e235c7)’ and ‘[getCurrentPose](http://docs.ros.org/en/jade/api/moveit_ros_planning_interface/html/classmoveit_1_1planning__interface_1_1MoveGroup.html#af3680fb747b0d570dac822893cef695f)’, but I think movegroup always read from ‘base\_link’ frame. Did I miss something? 😅 4. Is is possible to use ‘[Universal\_Robots\_ROS\_controllers\_cartesian](https://github.com/UniversalRobots/Universal_Robots_ROS_controllers_cartesian)’ with movegroup? It would be really grateful if you could share the source code link you know. Thank you. ---
**Author:** ![mauch](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@mauch](https://forum.universal-robots.com/u/mauch)\ **Post date:** [January 20, 2022, 10:40am UTC](https://forum.universal-robots.com/t/about-the-cartesian-trajectory-controllers-and-movegroup/18606/4 "2022-01-20T10:40:15Z")
There is no need to use movegroup to get the current tcp\_pose. You can simply use standard tf calls as explained in the [docs](http://wiki.ros.org/tf2/Tutorials/Writing%20a%20tf2%20listener%20%28Python%29). ---
**Author:** ![along893](https://avatars.discourse-cdn.com/v4/letter/a/cab0a1/32.png) [@along893](https://forum.universal-robots.com/u/along893)\ **Post date:** [January 24, 2022, 8:31am UTC](https://forum.universal-robots.com/t/about-the-cartesian-trajectory-controllers-and-movegroup/18606/5 "2022-01-24T08:31:17Z")
Thanks for the reply. With your help, I got ‘tool’ tf from ‘base’ using tf.TransformListener() Class, and the value of trans, rot is almost same as I commanded where the robot moved. [Cammand] ```auto [position: x: 0.5 y: -0.15 z: 0.8 orientation: x: -0.706824956994 y: 0.707388044877 z: 0.000562863771533 w: 0.000563312173597] ``` [Get tf] - ‘tool0’ from ‘base’ (not exactly the same with ee\_link) ```auto trans : [0.500013945413468, -0.15565131511976096, 0.7999185230416067] rot : [-0.7037114015832387, 0.7104859058080407, 0.00012586137875077213, -0.00015839442752342212] ``` Thanks However, still I don’t know how to make tool0 move from tool0 coordinate system. I thought it was possible with 3 steps before [1] add x:0.3m to tool0 link [2] read tool0(added x:0.3m) from base link and get target point [3] command tool0 target point from base link It’s quite tough for me to do all things in detail. Only one thing I want to know. Do you think it seems to be possible? Thank you.