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2015-08-12 04:35:36 -0500 answered a question Possibility of moving the ur10 universal robot with respect to the action goals being updated in its ROS topic "/follow_joint_trajectory/goal"?

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

2015-07-20 07:42:10 -0500 received badge  Popular Question (source)
2015-07-15 10:07:26 -0500 asked a question Possibility of moving the ur10 universal robot with respect to the action goals being updated in its ROS topic "/follow_joint_trajectory/goal"?

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)

2015-06-05 05:27:48 -0500 asked a question Gazebo GUI Error [Param.cc 181]:: Unable to set value [1,0471975511965976] and [0,100000001]

This question has been asked before in this forum at least once ( http://answers.ros.org/question/19940... ). Nevertheless, i haven't found the cause behind the occurrence of the following Gazebo GUI errors,

 - Error [Param.cc:181] Unable to set value [1,0471975511965976] for key[horizontal_fov]
 - Error [Param.cc:181] Unable to set value [0,100000001] for key[near]

Things performed :: I successfully installed ROS Indigo on Ubuntu (Description: 14.04.02 LTS, Codename: Trusty) 64-bit virtual machine by following the instructions from the website http://wiki.ros.org/indigo/Installati... .

Later, i tried to launch the gazebo simulator to visualize universal robot by going through the tutorial mentioned in the website http://wiki.ros.org/universal_robot/T... .

The following is the result of launching the gazebo simulator ::

... logging to /home/prof/.ros/log/6c565688-0b67-11e5-8411-0800272b2ea9/roslaunch-PROFPC-28231.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://PROFPC:58741/

SUMMARY
========

PARAMETERS
 * /arm_controller/action_monitor_rate: 10
 * /arm_controller/constraints/elbow_joint/goal: 0.1
 * /arm_controller/constraints/elbow_joint/trajectory: 0.1
 * /arm_controller/constraints/goal_time: 0.6
 * /arm_controller/constraints/shoulder_lift_joint/goal: 0.1
 * /arm_controller/constraints/shoulder_lift_joint/trajectory: 0.1
 * /arm_controller/constraints/shoulder_pan_joint/goal: 0.1
 * /arm_controller/constraints/shoulder_pan_joint/trajectory: 0.1
 * /arm_controller/constraints/stopped_velocity_tolerance: 0.5
 * /arm_controller/constraints/wrist_1_joint/goal: 0.1
 * /arm_controller/constraints/wrist_1_joint/trajectory: 0.1
 * /arm_controller/constraints/wrist_2_joint/goal: 0.1
 * /arm_controller/constraints/wrist_2_joint/trajectory: 0.1
 * /arm_controller/constraints/wrist_3_joint/goal: 0.1
 * /arm_controller/constraints/wrist_3_joint/trajectory: 0.1
 * /arm_controller/gains/elbow_joint/d: 100.0
 * /arm_controller/gains/elbow_joint/i: 500.0
 * /arm_controller/gains/elbow_joint/i_clamp: 100.0
 * /arm_controller/gains/elbow_joint/p: 1500.0
 * /arm_controller/gains/shoulder_lift_joint/d: 100.0
 * /arm_controller/gains/shoulder_lift_joint/i: 500.0
 * /arm_controller/gains/shoulder_lift_joint/i_clamp: 100.0
 * /arm_controller/gains/shoulder_lift_joint/p: 1500.0
 * /arm_controller/gains/shoulder_pan_joint/d: 100.0
 * /arm_controller/gains/shoulder_pan_joint/i: 500.0
 * /arm_controller/gains/shoulder_pan_joint/i_clamp: 100.0
 * /arm_controller/gains/shoulder_pan_joint/p: 600.0
 * /arm_controller/gains/wrist_1_joint/d: 0.0
 * /arm_controller/gains/wrist_1_joint/i: 0.0
 * /arm_controller/gains/wrist_1_joint/i_clamp: 0.0
 * /arm_controller/gains/wrist_1_joint/p: 100.0
 * /arm_controller/gains/wrist_2_joint/d: 0.0
 * /arm_controller/gains/wrist_2_joint/i: 0.0
 * /arm_controller/gains/wrist_2_joint/i_clamp: 0.0
 * /arm_controller/gains/wrist_2_joint/p: 100.0
 * /arm_controller/gains/wrist_3_joint/d: 0.0
 * /arm_controller/gains/wrist_3_joint/i: 0.0
 * /arm_controller/gains/wrist_3_joint/i_clamp: 0.0
 * /arm_controller/gains/wrist_3_joint/p: 100.0
 * /arm_controller/joints: ['shoulder_pan_jo...
 * /arm_controller/state_publish_rate: 25
 * /arm_controller/stop_trajectory_duration: 0.5
 * /arm_controller/topic: test
 * /arm_controller/type: effort_controller...
 * /joint_state_controller/publish_rate: 50
 * /joint_state_controller/type: joint_state_contr...
 * /robot_description: <?xml version="1....
 * /robot_state_publisher/publish_frequency: 50.0
 * /robot_state_publisher/tf_prefix: 
 * /rosdistro: indigo
 * /rosversion: 1.11.13
 * /use_sim_time: True

NODES
  /


 - arm_controller_spawner (controller_manager/spawner)
 - fake_joint_calibration (rostopic/rostopic)
 - gazebo (gazebo_ros/gzserver)
 - gazebo_gui (gazebo_ros/gzclient)
 - joint_state_controller_spawner (controller_manager/spawner)
 - robot_state_publisher (robot_state_publisher/robot_state_publisher)
 - spawn_gazebo_model (gazebo_ros/spawn_model)

auto-starting new master
process[master]: started with pid [28246]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 6c565688-0b67-11e5-8411-0800272b2ea9
process[rosout-1]: started with pid [28259]
started core service [/rosout]
process[gazebo-2]: started with pid [28262]
process[gazebo_gui-3]: started with pid [28266]
process ...
(more)