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How to control cartesian velocity?

asked 2017-10-06 11:17:59 -0600

AndresCampos gravatar image

I'm using a Fanuc M10iA robot from the ROS industrial package and I would like to generate a trajectory for this robot from a cartesian path (i.e. a list of cartesian positions and velocities).

Currently I use moveIt! and move_group->ComputeCartesianPath() to generate the robot trajectory. The robot moves but I don't know how to specify the velocities for the waypoints.

I want to move the robot with a given cartesian velocity and change this velocity in any point in the trajectory. How can I do this with ROS?

This is the code that i use to move the robot with MoveIt: (example package: )

#include <vector>
#include <ros/ros.h>
#include <eigen_conversions/eigen_msg.h>
#include <moveit/move_group_interface/move_group_interface.h>
#include <moveit_msgs/ExecuteKnownTrajectory.h>

int main(int argc, char **argv)
  ros::init(argc, argv, "robot_trajectory");
  ros::NodeHandle node;
  ros::AsyncSpinner spinner(1);

  moveit::planning_interface::MoveGroupInterface group("manipulator");

  // Create a trajectory (vector of Eigen poses)
  std::vector<Eigen::Affine3d, Eigen::aligned_allocator<Eigen::Affine3d> > way_points_vector;
  Eigen::Affine3d pose (Eigen::Affine3d::Identity());

  // Square belonging to XY plane
  pose.linear() <<
      1, 0, 0,
      0,-1, 0,
      0, 0, -1;
  pose.translation() << 0.8, 0.1, -0.1;
  pose.translation() << 1.0, 0.1, -0.1;
  pose.translation() << 1.0, 0.3, -0.1;
  pose.translation() << 0.8, 0.3, -0.1;

  // Copy the vector of Eigen poses into a vector of ROS poses
  std::vector<geometry_msgs::Pose> way_points_msg;
  for (size_t i = 0; i < way_points_msg.size(); i++)
    tf::poseEigenToMsg(way_points_vector[i], way_points_msg[i]);

  moveit_msgs::RobotTrajectory robot_trajectory;
  group.computeCartesianPath(way_points_msg, 0.05, 15, robot_trajectory);

  // Execute trajectory
  ros::ServiceClient executeKnownTrajectoryServiceClient = node.serviceClient<moveit_msgs::ExecuteKnownTrajectory>(
  moveit_msgs::ExecuteKnownTrajectory srv;

  srv.request.wait_for_execution = true;
  srv.request.trajectory = robot_trajectory;;

   return 0;
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Hi, I was looking for something similar to what you have asked for controlling the cartesian velocity of the waypoints. I searched but it seems its not yet done. I want to know if you were able to solve it?

sharath gravatar image sharath  ( 2018-05-22 01:10:49 -0600 )edit

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answered 2017-10-10 10:25:18 -0600

v4hn gravatar image

MoveIt currently does not provide a method to request specific end-effector velocities.

We would welcome such an addition and it is clearly feasible. You can generate a valid time-parameterization for your cartesian trajectory using the moveit_core/trajectory_processing module. These methods generate velocities according to the maxima specified for each joint. If you want to attain a constant end-effector velocity you can rescale the timing relative to the slowest segment.

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Is there still interest in adding this to the MoveIt source code? If so, how you would like this functionality to be added to the overall MoveIt architecture? I've added a function to moveit_core/trajectory_processing/iterative_time_parameterization.cpp that rescales the timing based on a desired cartesian velocity for a specified end effector link. I was planning on using the MoveGroupInterface to pass the desired velocity and end effector link to the trajectory. I am not a MoveIt expert by any means, so if there is an alternate way you would like this implemented please let me know.

Alternatively, I could implement it separately from any time parameterization after the trajectory has been generated from the move_group.plan function call. This way, no existing data structures would need to be changed.

kwh5484 gravatar image kwh5484  ( 2019-07-11 09:54:03 -0600 )edit

Speaking for myself: yes, there would be interest.

but a comment on an already answered ROS Answers question is not necessarily the best place to discuss/announce this.

I would suggest to post an issue on the MoveIt issue tracker on github.

gvdhoorn gravatar image gvdhoorn  ( 2019-07-11 14:42:41 -0600 )edit

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Asked: 2017-10-06 11:17:59 -0600

Seen: 1,553 times

Last updated: Oct 10 '17