ROS Resources: Documentation | Support | Discussion Forum | Index | Service Status | ros @ Robotics Stack Exchange
Ask Your Question
1

trajectory error in simulation / controller parameters

asked 2011-02-14 16:25:54 -0600

Tully gravatar image

I'm a student at University of Stuttgart and work at IPA Fraunhofer with the Care-O-bot. We have here some problems with the planned trajectory in simulation. The actual executed trajectory of the robot arm in rviz differs from the planned one (display_path (motion_planning_msgs/DisplayTrajectory)). We guess that it comes from the dynamic model and the chosen controller parameters in the arm_controller_cob3-1.yaml file (cob_simulation/cob_controller_configuration_gazebo/ros/controller). So we're looking for ideas, hints and rules how to choose these parameters or explanations where the trajectory error could come from.

Thanks in advance for your help!

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
3

answered 2011-02-14 16:26:32 -0600

tfoote gravatar image

The path you are seeing is indeed the path that comes from the planner. But there's an extra step that move_arm goes through of filtering the trajectory using a spline_shortcutting method that tries to find ways to make the path shorter while also assigning reasonable velocities when it can. This can change the trajectory quite a bit. If you want to see the path that move_arm will actually be sending to be executed you'll need to change the code a bit. Overlay arm_navigation. In whatever version of the code you are running find the line:

visualizePlan(current_trajectory_); //move_arm_simple_action.cpp:1361 in unstable.

Comment this line out, and then copy it an add it after the line:

current_trajectory_ = filtered_trajectory; //move_arm_simple_action.cpp:1422 in unstable visualizePlan(current_trajectory_); // copied from 1361

The trajectory you see in rviz will now be the actual one getting passed to the controller. I expect it will look much more like the executed trajectory.

edit flag offensive delete link more

Question Tools

Stats

Asked: 2011-02-14 16:25:54 -0600

Seen: 628 times

Last updated: Feb 14 '11