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Possibility of moving the ur10 universal robot with respect to the action goals being updated in its ROS topic "/follow_joint_trajectory/goal"?

asked 2015-07-15 10:07:26 -0500

Sriniwas gravatar image

Dear ROS developers & users,

Let me formulate my situation.

Aim :: To move the ur10 universal robot with respect to the updated action goals which are being published to its corresponding ROS topic "/follow_joint_trajectory/goal"

Things performed ::

  • Played around with the tutorials provided in the ros-industrial package of universal robot using the website link ( http://wiki.ros.org/universal_robot/T... )

  • Checked which particular ROS topic should I have to publish a new joint-space goal. The ROS topic was found to be "/follow_joint_trajectory/goal". Type of this ROS topic is "control_msgs/FollowJointTrajectoryActionGoal". Also, i had a look at the message sturcture of "control_msgs/FollowJointTrajectoryActionGoal" using the website link ( http://docs.ros.org/fuerte/api/contro... )

For the sake of completeness, the complete message structure of "control_msgs/FollowJointTrajectoryActionGoal" looks in the following manner.

ros@rosPC:~$ rosmsg show control_msgs/FollowJointTrajectoryActionGoal

std_msgs/Header header

uint32 seq

time stamp

string frame_id

actionlib_msgs/GoalID goal_id

time stamp

string id

control_msgs/FollowJointTrajectoryGoal goal

trajectory_msgs/JointTrajectory trajectory

std_msgs/Header header
   uint32 seq
   time stamp
   string frame_id

string[] joint_names

trajectory_msgs/JointTrajectoryPoint[] points
  float64[] positions
  float64[] velocities
  float64[] accelerations
  float64[] effort
  duration time_from_start

control_msgs/JointTolerance[] path_tolerance

 string name
 float64 position
 float64 velocity
 float64 acceleration

control_msgs/JointTolerance[] goal_tolerance

 string name
 float64 position
 float64 velocity
 float64 acceleration

duration goal_time_tolerance

  • To be precise, I neglected the following parts of the above mentioned message while publishing the action goals to the ROS topic "follow_joint_trajectory/goal".

Field --- Object => Class (My interpretation of the message structure)

std_msgs/Header header => control_msgs/FollowJointTrajectoryActionGoal

time stamp ---- actionlib_msgs/GoalID goal_id => control_msgs/FollowJointTrajectoryActionGoal

std_msgs/Header header => trajectory_msgs/JointTrajectory trajectory

duration time_from_start ---- trajectory_msgs/JointTrajectoryPoint[] points => trajectory_msgs/JointTrajectory trajectory

duration goal_time_tolerance => control_msgs/FollowJointTrajectoryActionGoal

  • So far, the ROS topic "/follow_joint_trajectory/goal" is clearly published with the action goals

Typical action goal published to the ROS topic "/follow_joint_trajectory/goal" and the message looks in the following way.

header:

seq: 0

stamp:     

   secs: 0    

   nsecs: 0

frame_id: ''

goal_id:

stamp: 

   secs: 0

   nsecs: 0

 id: 0

goal:

trajectory: 

  header: 

    seq: 0

    stamp: 
      secs: 0
      nsecs: 0

    frame_id: ''

  joint_names: ['shoulder_pan_joint', 'shoulder_lift_joint', 'elbow_joint', 'wrist_1_joint', 'wrist_2_joint', 'wrist_3_joint']

  points: 
    - 
      positions: [1.4770721197128296, -2.000670909881592, 1.7188003063201904, -2.132617950439453, -1.6139060258865356, -0.28640851378440857]

      velocities: [1.4770721197128296, -2.000670909881592, 1.7188003063201904, -2.132617950439453, -1.6139060258865356, -0.28640851378440857]

      accelerations: [0.7385360598564148, -1.000335454940796, 0.8594001531600952, -1.0663089752197266, -0.8069530129432678, -0.14320425689220428]

      effort: []

      time_from_start: 
        secs: 0
        nsecs: 0
    - 

      positions: [1.9598301649093628, -1.015956163406372, 1.7667968273162842, -2.3582887649536133, -1.60133957862854, -0.4801400899887085]

      velocities: [1.9598301649093628, -1.015956163406372, 1.7667968273162842, -2.3582887649536133, -1.60133957862854, -0.4801400899887085]

      accelerations: [0.9799150824546814, -0.507978081703186, 0.8833984136581421, -1.1791443824768066, -0.80066978931427, -0.24007004499435425]

      effort: []

      time_from_start: 
        secs: 0
        nsecs: 0

path_tolerance: -

  name: pt
  position: 0.0872664600611
  velocity: 0.0872664600611
  acceleration: 0.0872664600611

goal_tolerance: -

  name: gt
  position: 0.0872664600611
  velocity: 0.0872664600611
  acceleration: 0.0872664600611

goal_time_tolerance:

secs: 0
nsecs: 0

ros@rosPC:~$ rostopic echo /follow_joint_trajectory/goal

Result :: Even though the action goals are published on the desired ROS topic (i.e., "/follow_joint_trajectory/goal"), ur10 robot doesn't move at all

Conclusion drawn from the result :: May be I have to fill the neglected parts ... (more)

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Comments

Hi I'm also facing some problems with moving the ur10. I have one question though, are you using the position of joints to move? why not put a final position for say the end effector the make the robot move in order to get there?

JuanTelo gravatar imageJuanTelo ( 2018-02-01 10:09:02 -0500 )edit

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answered 2015-08-12 04:35:36 -0500

Sriniwas gravatar image

updated 2015-08-12 04:36:25 -0500

I solved my problem regarding why the ur10 robot was not moving.

The conclusion which i stated before is right. The action goals which i am publishing in the first place has to be filled with relevant header info, stamp info of goal_id and time_from_start of the trajectory field present within the goal object of the action goal itself.

The thing which was really missing was the actionlib::SimpleActionCleint interface which is required to send the goal to the ur10 robot (here the ur10 robot acts like a server). I referred to this link Moving the arm using the Joint Trajectory Action to realize how to move the ur10 arm.

If anyone is facing a similar problem, please let me know.

BR,

Sriniwas

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Comments

Hi, I'm also face the similar problem. Can you please share your file because I'm also using the same model UR10?

semmas gravatar imagesemmas ( 2015-08-28 11:42:13 -0500 )edit

Also, all of your waypoints have zero time_from_start. This field represents the time relative to the trajectory start at which the waypoint should be reached. Trajectory start time is given by the trajectory_msgs/JointTrajectory header timestamp. Zero timestamp (default) means start immediately

Adolfo Rodriguez T gravatar imageAdolfo Rodriguez T ( 2015-08-31 02:51:27 -0500 )edit

Hi, I'm facing a similar problem. Can you please contact me: juantelo95@gmail.com I'm facing problems with the structure of the message

JuanTelo gravatar imageJuanTelo ( 2018-02-05 04:19:27 -0500 )edit

hi, i am also facing similar problem with the message structure. i am also trying to publish message to the jointTrajectory to move the robot.Thank you. please contact me at faltukaacco@gmail.com or if there is any other way to contact you regarding this problem.

_suresh gravatar image_suresh ( 2018-09-25 20:19:23 -0500 )edit

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Asked: 2015-07-15 10:07:26 -0500

Seen: 1,755 times

Last updated: Aug 12 '15