Fix for #517: create a getRobotPose method on move_base

[corot]

instead of using that on the costmaps.

Solves (I would say surprisingly) the

"Unable to get starting pose of robot, unable to create global plan"

problem.

Change is very simple and hardly harmful. But I cannot tell what is exactly fixing nor why...

[mikeferguson]

I like this PR -- but I don't like the breaking of ABI in the Costmap2dROS class (which will cause all sorts of hell on people with out-of-sync plugins, which is tough to track down). Here's my proposal:

• I will cherry-pick this as-is into Lunar. There are far fewer users and we've still been fixing build issues over there, so stability should not yet be expected.

• We update this PR to hard-code name+tolerance as parameters to MoveBase::getRobotPose() since ABI of MoveBase class does not matter.

• Once we merge this updated version into indigo, I will cherry-pick to Kinetic

[mikeferguson]

ABI in MoveBase doesn't matter, for Indigo+Kinetic -- let's add the name & transform_tolerance to this function signature, and then hard code them above (not great, but avoids ABI break). For Lunar -- let's go ahead and put this PR just this way (with the Costmap2DROS ABI change)

[corot]

👍

Btw, I think I understand better now the problem I was solving with this PR: As we look the global costmap before calling the global planner (

navigation/move_base/src/move_base.cpp

Line 450 in ada542f

boost::unique_lock<costmap_2d::Costmap2D::mutex_t> lock(*(planner_costmap_ros_->getCostmap()->getMutex()));

), it stops updating and get outdated, so we get the 'Costmap2DROS transform timeout. Current time: 1470136643.4973, global_pose stamp: 1470136643.1959, tolerance: 0.3000' WARN.
As I mention on #441, I think this costmap locking should be responsibility of the planners, and last for the shorter possible time.

[corot]

btw @mikeferguson, do you want me to apply the requested changes? Or will you do by yourself?

[DLu]

This was merged into lunar in #601 and is a part of melodic and noetic as well.