Problem running SBPL on ARM (Odroid-U3)

asked 2014-10-07 09:23:12 -0500

Markus Eich
202 ●14 ●20 ●24

updated 2014-10-08 04:58:46 -0500

Hi all,

I am facing a strange problem. I am using ROS move_base and SBPL for motion-primitive-based path planning. I have generated some motion primitives for SBPL and everything works fine using my laptop (Intel i5, Ubuntu 14.04). The robot plans the path and moves fine along the path.

Now I am using the very same modules (and configs) on my Odroid U3 (ARM quadcore) and it cannot find a solution. Top shows that the core is at 100%. Here is the output from move_base

[ INFO] [1412691428.999248673]: Using plugin "obstacle_layer"

[ INFO] [1412691429.127272381]: Subscribed to Topics:

[ INFO] [1412691429.172789423]: Using plugin "inflation_layer"

[ INFO] [1412691429.443358089]: Name is SBPLLatticePlanner

[ INFO] [1412691430.931921673]: Planning with ARA*

[ INFO] [1412691430.932365757]: [sbpl_lattice_planner] Initialized successfully

[ INFO] [1412691430.989290632]: Using plugin "obstacle_layer"

[ INFO] [1412691431.241103424]: Subscribed to Topics:

[ INFO] [1412691431.286346674]: Using plugin "inflation_layer"

[ INFO] [1412691431.688199674]: Created local_planner base_local_planner/TrajectoryPlannerROS

[ INFO] [1412691431.732307049]: Sim period is set to 0.10

[ INFO] [1412691432.897083008]: odom received!

[ INFO] [1412691492.209781994]: [sbpl_lattice_planner] getting start point (3.48925,-0.84064) goal point (2.00517,-1.3133) [ INFO] [1412691502.490063749]: Solution not found

[ WARN] [1412691502.492333249]: Map update loop missed its desired rate of 2.0000Hz... the loop actually took 10.0025 seconds

[ INFO] [1412691502.492543791]: [sbpl_lattice_planner] getting start point (3.48925,-0.84064) goal point (2.00517,-1.3133)

[ INFO] [1412691512.771037004]: Solution not found

I am using the following repos of the modules:

ROS indigo

sbpl_lattice_planner: https://github.com/meyerj/sbpl_lattic...

sbpl: https://github.com/sbpl/sbpl.git

Any ideas? I actually have no Idea where to start looking.

Cheers,

Markus

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4

answered 2015-02-16 03:05:16 -0500

philipp.schmutz
56 ●3 ●2

The problem is the ambiguity of the char datatype. On x86 gcc it defaults to signed, on ARM to unsigned. This results in negative values getting flipped.

See here: http://www.arm.linux.org.uk/docs/faqs...

and here: https://github.com/sbpl/sbpl/blob/mas...

one solution is to simply compile with the -fsigned-char switch, forcing all chars to be signed

## Compiler flags
if(CMAKE_COMPILER_IS_GNUCXX)
    ## signed char is default on x86 gcc, not on arm however.
    set(CMAKE_CXX_FLAGS "-fsigned-char")        
endif()

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https://github.com/sbpl/sbpl/pull/27

philipp.schmutz ( 2015-02-16 03:26:48 -0500 )edit

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answered 2014-10-08 11:00:50 -0500

ahendrix

47576 ●179 ●367 ●662 http://namniart.com/

In general, this error means that SBPL timed out before it could find a path connecting that start and goal points.

There are a few things you can try (in order from easiest to hardest):

Make sure SBPL and sbpl_lattice_planner are compiled in release mode ( catkin_make -DCMAKE_BUILD_TYPE=Release )
Increase the global planner timeout
Decrease the global costmap resolution
Decrease the number of SBPL primitives