Jack Sparrow's profile - activity

Hi,

I have problem with implementing navigation to work with multiple robots. Errors:

Waiting on transform from /robot_1/base to /map to become available before running costmap, tf error: Frame id /robot_1/base does not exist!
Waiting on transform from /robot_2/base to /map to become available before running costmap, tf error: Frame id /robot_2/base does not exist!

Probably, the problem is in transformations that transform /map to /base and not from /map to /robot_1/base. I use groups/namespaces in launch file to separate each robot node with correspondiong move_base node from other nodes. To run navigation stack I launch robot_configuaration.launch and move_base.launch. I have found the following solution:

<launch>
  <group ns="robot_1">
    <param name="tf_prefix" value="robot_1"/>
    <node pkg="usarsim" type="usarsim.py" respawn="false" name="usarsim_1" output="screen">
  </group>
  <group ns="robot_2">
    <param name="tf_prefix" value="robot_2"/>
    <node pkg="usarsim" type="usarsim2.py" respawn="false" name="usarsim_2" output="screen">
  </group>

and

<launch>
  <node name="map_server" pkg="map_server" type="map_server" args="/home/user/Desktop/ROS/map.pgm 0.05" respawn="false">
  </node>

  <group ns="robot_1"><br>
    <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
      <rosparam file="$(find robot_2dnav)/costmap_common_params.yaml" command="load" ns="global_costmap" />
      <rosparam file="$(find robot_2dnav)/costmap_common_params.yaml" command="load" ns="local_costmap" />
      <rosparam file="$(find robot_2dnav)/local_costmap_params.yaml" command="load" />
      <rosparam file="$(find robot_2dnav)/global_costmap_params.yaml" command="load" />
      <rosparam file="$(find robot_2dnav)/base_local_planner_params.yaml" command="load" /><br>
    </node><br>
  </group>

  <group ns="robot_2">
    <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
    ...same as for group_1

but this doesn't work. Is there some solution to automatically map all topics and tf's directly from .launch file?

Hi,

I have trouble of understanding how navigation stack works. After days of debugging code to work with navigation stack I have concluded that its either problem in tf or I dont really understand how navigation stack work. Specifically I have a couple of questions/problems:

1. When I change tf to some reasonable parameters from my initial parameter, that should work, I get that my laser sensor is out of range, exactly - on some negative x or y positions. Does navigation work only with positive x and y?
   
2. My simulation is left oriented, so this might be problem with getting to work with navigation. But, when I left x an y signed positive or negative as I get from my odometry or change x to -x to compensate left-right orientation my robot's footprint moves in rviz always in the same direction. Should't be that in opposite direction? Is navigation right oriented? What problem I might get with left-right orientations?
   
3. My main problem is that when the robot in, let's say, position (x,y,orient)=(5,5,0) /map frame, and I send goal from rviz in /map frame to (6,5,0), robot gets positive x command velocity from navigation, but when the goal point is reached robot remains to move in +x direction, the output from navigation (cmd_vel) remains the same as before reaching goal. Same problem with y direction, both + and -y.

Some help needed, thanks.

Hi,

I have tried to setup navigation stack to work with the robot from USARSim the same way as in tutorials, but when I start robot_configuration.launch and move_base.launch I get this error related to odometry:

Traceback (most recent call last):
  File "/home/my_name/ros/usarsim/nodes/my_robot_nav.py", line 127, in <module>
    pub_odom.publish(odom)
  File "/opt/ros/diamondback/stacks/ros_comm/clients/rospy/src/rospy/topics.py", line 677, in publish
    self.impl.publish(data)
...
    buff.write(_struct_7d.pack(_x.pose.pose.position.x, _x.pose.pose.position.y, _x.pose.pose.position.z, _x.pose.pose.orientation.x, _x.pose.pose.orientation.y, _x.pose.pose.orientation.z, _x.pose.pose.orientation.w))
AttributeError: 'numpy.ndarray' object has no attribute 'x'
[usarsim-1] process has died [pid 11052, exit code 1].
log files: /home/hrvoje/.ros/log/1bf16950-642a-11e0-894b-000c29c48bc7/usarsim-1*.log*

Section of code that publish odom:

odom_quat = tf.transformations.quaternion_from_euler(0,0,some_odom_theta_data)

odom.header.stamp = rospy.Time.now()

odom.header.frame_id = "odom"

odom.pose.pose.position.x = some_odom_x_data
odom.pose.pose.position.y = some_odom_y_data
odom.pose.pose.position.z = 0.0
odom.pose.pose.orientation = odom_quat

odom.child_frame_id = "base_link"
odom.twist.twist.linear.x = 0.0
odom.twist.twist.linear.y = 0.0
odom.twist.twist.linear.z = 0.0
pub_odom.publish(odom)

My odometry returns only position and orientation, but not the values for velocity!

Any suggestions will be helpful. Thanks in advance. hv

Well, it turns out that the python version of transformBroadcaster has a bug in that it doesn't read the tf_prefix parameter. I've filed a ticket to have this fixed here: https://code.ros.org/trac/ros-pkg/ticket/4943.

In the meantime, you have a couple of options:

1) Write the search param logic yourself for the transformBroadcaster, submit a patch to the above ticket, get mad props from the ROS community for fixing a bug :)

2) Have a parameter on your node that allows you to change the frame name before you pass it to the transformBroadcaster.

3) Switch to the C++ API which works as expected.

Hope this helps.