mardo's profile - activity

Hi,

I was wondering whether there is existing support for synchronizing the callbacks of multiple subscribers based on the order of the timestamps.

For instance, I have one sensor source running measuring at 200 Hz, and another at 20 Hz. Currently the timestamps of the 20 Hz source are ~0.1 seconds later than the 200 Hz source without any message filtering.

I've looked at http://wiki.ros.org/message_filters , and TimeSynchronizer provides close to what I'm looking for. However, it appears that if I was to use this, I would drop 90% of the faster sensor measurements, as the callback would not be executed until the 20 Hz source has a measurement.

Am I understanding this correctly, and are there any existing solutions?

Thanks.

Have you set ROS_MASTER_URI on both the device and the computer?

I've found that the visualisation performance (Gazebo and RViz) is quite poor when running ROS in Virtualbox on my Mac. I have also had issues with sensors working correctly in a virtual machine.

I eventually made an Ubuntu partition specifically for ROS, and that has worked out very well. If you're happy with the more permanent nature of that approach, I would strongly recommend it.

Is this what you are looking for?

https://github.com/clearpathrobotics/...

If you're looking for the actual firmware that runs on the motor controllers themselves, you would be best off contacting Clearpath directly - they are very helpful.

Try changing the following line in your CMakeLists.txt

find_package(catkin REQUIRED COMPONENTS geometry_msgs message_generation)

to

find_package(catkin REQUIRED COMPONENTS roscpp tf geometry_msgs message_generation)

Hey David,

I happened to be working on the same thing as you with regards to adding cost functions as plugins to the DWAPlanner and came across this exact same problem.

I believe the issue is that you cannot link against the same library that contains the plugin that you are trying to load.

I can get your example to run with the following changes to your CMakeLists.txt:

 
add_library(cost_functions 
  src/map_grid_cost_function.cpp
    src/goal_dist_cost_function.cpp
    src/path_dist_cost_function.cpp
    src/offset_grid_cost_function.cpp
    src/goal_align_cost_function.cpp
    src/path_align_cost_function.cpp
  src/obstacle_cost_function.cpp
  src/oscillation_cost_function.cpp
  src/prefer_forward_cost_function.cpp
)
 
add_library(dwa_local_planner src/dwa_planner.cpp src/dwa_planner_ros.cpp src/simple_scored_sampling_planner.cpp)
target_link_libraries(dwa_local_planner base_local_planner)
add_dependencies(dwa_local_planner dwa_local_planner_gencfg)
add_dependencies(dwa_local_planner nav_msgs_gencpp)
add_executable(plugin_quiz src/plugin_quiz.cpp)
target_link_libraries(plugin_quiz ${catkin_LIBRARIES} dwa_local_planner)
 
add_executable(plugin_quiz2 src/plugin_quiz2.cpp)
target_link_libraries(plugin_quiz2 ${catkin_LIBRARIES} dwa_local_planner)
 

However, I now get the following error after running:

Warning: class_loader::ClassLoader: SEVERE WARNING!!! Attempting to unload library while objects created by this loader exist in the heap! You should delete your objects before attempting to unload the library or destroying the ClassLoader. The library will NOT be unloaded.
         at line 94 in /tmp/buildd/ros-hydro-class-loader-0.2.3-0precise-20131010-0141/src/class_loader.cpp
Segmentation fault (core dumped)

The segfault appears to be occurring with the deletion of the WorldModel in the destructor of ObstacleCostFunction - changing world_model_ to a boost::shared_ptr appears to fix this, though I'm not sure what the root cause is. I'm not sure about the cause of the class_loader warning either, but calling tc_.reset() at the end of your plugin_quiz2.cpp appears to fix it.

With these changes, I intermittently get the following error when the program finishes:

plugin_quiz2: pthread_mutex_lock.c:62: __pthread_mutex_lock: Assertion `mutex->__data.__owner == 0' failed.
Aborted (core dumped)

Let me know if that helps. Looking forward to seeing this addition to the planner!