memo/20120311
created 2012-03-11 modified 2012-03-12
| ROS | turtlebot | turtlebot_simulator | gazebo |
| Link | memo |
|---|---|
| Challenges with headless turtlebot_gazebo on remote machine | ROS answers.ros.org |
| ticket #132 |
I found "using variables without initialize" bug in "simulator_gazebo_plugins".
That cause the corrupted very large value of odometry {x, y}.
[problem]
When you try to use turtlebot simulator (gazebo),
sometimes the node "/gazebo" publishes the topic "/odom" with very large
initial position {x, y} like 1e+31 or so.
[cause]
In turtlebot_gazebo_plugins/src/gazebo_ros_create.cpp,
variables below are used without being initialized.
- prev_update_time
- odom_pose[0]
- odom_pose[1]
- odom_pose[2]
I know that recentry turtlebot_gazebo_plugins/src/gazebo_ros_create.cpp was patched
about NaN value (in GazeboRosCreate::UpdateChild()) .
The patch didn't fix the problem I found.
[environment]
- ubuntu 11.10 32bit
- ros-electric (updated with apt-get)
[how to reproduce]
(not 100%. because that is caused with "using uninitialized variable" in C++.)
Start 3 terminals separately and type it.
$ roscore $ roslaunch turtlebot_gazebo turtlebot_empty_world.launch $ rostopic echo /odom
Check values of pose.pose.position.x and y.
If it shows like below, you successed to reproduce.
pose:
pose:
position:
x: 1.86493744726e+31
y: 4.86171422416e+30
[how to fix]
initialize variables.
[patch]
keizo@soi:~/ros_workspace/turtlebot_gazebo_plugins.keizo/src$ diff -c /opt/ros/electric/stacks/turtlebot_simulator/turtlebot_gazebo_plugins/src/gazebo_ros_create.cpp .
*** /opt/ros/electric/stacks/turtlebot_simulator/turtlebot_gazebo_plugins/src/gazebo_ros_create.cpp 2012-02-29 07:52:33.000000000 +0900
--- ./gazebo_ros_create.cpp 2012-03-11 22:59:59.026536682 +0900
***************
*** 153,158 ****
--- 153,159 ----
js_.velocity.push_back(0);
js_.effort.push_back(0);
+ prev_update_time_ = 0;
last_cmd_vel_time_ = 0;
}
***************
*** 172,177 ****
--- 173,184 ----
if (joints_[FRONT]) set_joints_[FRONT] = true;
if (joints_[REAR]) set_joints_[REAR] = true;
+ //initialize time and odometry position
+ prev_update_time_ = last_cmd_vel_time_ =
+ Simulator::Instance()->GetSimTime();
+ odom_pose_[0] = 0.0;
+ odom_pose_[1] = 0.0;
+ odom_pose_[2] = 0.0;
}
void GazeboRosCreate::FiniChild()
[ Unnecessary additional information ]
[indirect problem]
When you try to use turtlebot simulator (gazebo) and slam_gmapping,
the node slam_gmapping dies with a message "bad_alloc" exception.
[cause]
Ordinary, the initial value of odometory's {x, y} should be nearly equal to zero.
but it shows sometimes very large like 1e+31 or so.
When the node "slam_gmapping" receives that large value, it try to enlarge map too much.
And it cause a "not enough memory" situation and "bad_alloc" exception.
If you want to reproduce, you need to add "output_frame" param described blelow
to turtlebot_gazebo/launch/robot.launch .
<node pkg="robot_pose_ekf parameter" .... > .... <param name="output_frame" value="odom"/> </node>
[comment]
I'm not good at English, I apologize about my poor English.
I hope this information helps you. and also me.
ROS の gazebo
タートルボットのシミュレータ(gazebo)で、トピック /odom の x, y の初期値が不正に巨大な値になっています。マップを作成するため slam_gmapping を起動すると、オドメトリの x, y が巨大であるため、マップを拡張しようとしてたくさんのメモリを確保しようとし、bad_alloc 例外を吐いて落ちます。
原因は、turtlebot_gazebo_plugins/src/gazebo_ros_create.cpp にて、
以下の変数を未初期化で使ってるから。なんとまぁ。
- prev_update_time
- odom_pose[0]
- odom_pose[1]
- odom_pose[2]
対処は、初期化すること。
チケット出してみました。