Segfault when validating MultiDOF trajectories

[TroyCordie]

Description

Segfault when executing trajectory with custom action file. New to moveit so I'm hoping I might get pointed in the right direction or this might flag to someone in the know.

Your environment

• ROS Distro: [Kinetic]
• OS Version: Ubuntu 16.04
• Source
• 0744817

Steps to reproduce

I have been attempting to run the simulator located at https://github.com/wilselby/ROS_quadrotor_simulator.

Expected behaviour

the custom action file should implement a multi-degree of freedom joint and by all accounts has been working.

Actual behaviour

When executing a planned trajectory the code segfaults resulting in the following backtrace.

Backtrace or Console output

https://gist.github.com/TroyCordie/55de6da4ec32112981d7ba4c38512298

[v4hn]

Ouch, the validation was added recently and apparently there is a bug w.r.t. MultiDOF trajectories.

You can skip it (and most likely therefore the segfault) by setting the validation tolerance to 0.0 here in your moveit config.

It would help us a lot if you could figure out in which line the segfault occurs or give us an example trajectory to debug this!

Very sorry for the inconvenience, this was an often requested safety feature, so we backported it to indigo.

[TroyCordie]

Thank you for the response.
This fix does indeed skip the section of code that was segfaulting, I will see if I can dig in the next few days and find the culprit.

Though I am a bit confused by the topic the trajectory is now being output on /execute_trajectory/... I had assumed the topic /multi_dof_joint_trajectory_action/... would be the topic. This may just be a generic question so I will also ask it in the google groups.

[v4hn]

I don't understand the question, actually. Please raise generic questions on http://answers.ros.org It would be really great if you could look into the segfault a bit more and report back! You do not by any chance have a gazebo / moveit demo mode setup ready for testing?

[TroyCordie]

I do have a gazebo model I am trying to tie into moveit, when I get something happening between the two I'll dig deeper into the segfault.

[TroyCordie]

I have finaly had a chance to follow this up and the issue is in
bool TrajectoryExecutionManager::validate(const TrajectoryExecutionContext& context) const located in moveit_ros/planning/trajectory_execution_manager/src/trajectory_execution_manager.cpp

specifically if (positions.size() != n) on line ~963.

The issue arises when planning for a multi dof joint with out any other joint as trajectory.joint_trajectory.points.front().positions is empty. c is not a strong point but this is a null pointer?

currently, my fix is to add the check

if(!trajectory.joint_trajectory.points.empty())
{
......
}
else if(!trajectory.multi_dof_joint_trajectory.points.empty())
{
ROS_INFO_NAMED("move_group", "multi dof joint trajectory valadation not implmented");
return true;
}