Improvements to the global planner and move base

Improved the Gradient extraction logic 
Added loop check to the GridPath extractor
Added GridPath extractor as a backup extractor (when the gradient extractor is used - which sometimes is unable to extract a path using the value function)
Added plannerThread over clocking - so that when a new goal comes in - the planner responds immediately
Added option to the move_base so that when the over clocking is enabled - only if the option is set will the planner get called immediately when the controller fails - if you expect dynamic obstacles to be in the environment - best option is not to set this flag 

I didn't want it to immediately replan - this can have bad consequences
when there are dynamic obstacles in the environment - ideally the robot
should wait for a bit to see if the person would move (and the path becomes
feasible)


On Thu, Aug 14, 2014 at 8:18 PM, Dejan Pangercic <notifications@github.com>
wrote:

> In move_base/cfg/MoveBase.cfg:
>
> >  gen.add("controller_frequency", double_t, 0, "The rate in Hz at which to run the control loop and send velocity commands to the base.", 20, 0, 100)
> >  gen.add("planner_patience", double_t, 0, "How long the planner will wait in seconds in an attempt to find a valid plan before space-clearing operations are performed.", 5.0, 0, 100)
> >  gen.add("controller_patience", double_t, 0, "How long the controller will wait in seconds without receiving a valid control before space-clearing operations are performed.", 5.0, 0, 100)
> > +gen.add("immediately_replan_on_controller_failure", bool_t, 0, "Set true if you want the planner to immediately respond if the controller fails - (only relavent if over clocking the planner)", False)
>
> It seems that these params are not yet in the launch files?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/bosch-ros-pkg/navigation/pull/11/files#r16278890>.
>