Hello,

I'm using ROS kinectic on ubuntu 16.04 on an HP laptop. I made my own "real/physical" 2WD robot, and now I want to use ROS navigation stack to get it to move around autonomously. I'm currently struggling with the real robot. Typical behavior is that after the robot accepts a 2DNav goal, it starts navigating to the goal, then hesidates, rotates on himself, then continues rotating forever. A friend of mine suggested to model my physical environment in gazebo, then use the ROS navigation stack in gazebo, tune the navigation parameters until it works decently in gazebo, then reuse those navigation parameters for the real robot.

So here I am, struggling to get the simulated robot to navigate.

Firing gazebo works. the world I created is ok. 2WD plugin of gazebo feels fine when i teleop it with a keyboard. The mapping process worked just fine. I publish the previously recorded map, it works. The published /odom and /scan values seems correct too. I can see them in rviz as expected. rostopic echo /scan and rostopic echo /odom feels fine as well.

The problem is that when I launch amcl, I keep getting the following warning:

[ WARN] [1537204065.051924673, 3433.606000000]: No laser scan received (and thus no pose updates have been published) for 34139472.000000 seconds.  Verify that data is being published on the /scan topic.
[ WARN] [1537204080.975562709, 3448.606000000]: No laser scan received (and thus no pose updates have been published) for 34139472.000000 seconds.  Verify that data is being published on the /scan topic.
[ WARN] [1537204096.883037473, 3463.606000000]: No laser scan received (and thus no pose updates have been published) for 34139472.000000 seconds.  Verify that data is being published on the /scan topic.
[...]

Here is a typical /scan message (taken somehow later)

user@ubuntu:~$ rostopic info /scan
Type: sensor_msgs/LaserScan


Publishers:
 * /gazebo (http://ubuntu:40085/)

Subscribers:
 * /amcl (http://ubuntu:38221/)

user@ubuntu:~$ rostopic echo -n 1 /scan
header:
  seq: 42106
  stamp:
    secs: 4001
    nsecs: 770000000
  frameid: "sensorlaser"
anglemin: 0.0
anglemax: 6.27319002151
angleincrement: 0.0174740664661
timeincrement: 0.0
scantime: 0.0
rangemin: 0.10000000149
range_max: 18.0
ranges: [0.14208605885505676, 0.11974052339792252, ..., 1.9066493511199951, 1.8749361038208008]

intensities: [-3.16707076146899e+24, ... , 0.0]

user@ubuntu:~$

When i look into the node, it seems amcl is indeed connected to /scan.

user@ubuntu:~$ rosnode info amcl

Node [/amcl] Publications: * /amcl/parameterdescriptions [dynamicreconfigure/ConfigDescription] * /amcl/parameterupdates [dynamicreconfigure/Config] * /amclpose [geometrymsgs/PoseWithCovarianceStamped] * /particlecloud [geometrymsgs/PoseArray] * /rosout [rosgraphmsgs/Log] * /tf [tf2_msgs/TFMessage]

Subscriptions: * /clock [rosgraphmsgs/Clock] * /initialpose [unknown type] * /map [navmsgs/OccupancyGrid] * /scan [sensormsgs/LaserScan] * /tf [tf2msgs/TFMessage] * /tfstatic [tf2msgs/TFMessage]

Services: * /amcl/getloggers * /amcl/setloggerlevel * /amcl/setparameters * /globallocalization * /requestnomotionupdate * /setmap

contacting node http://ubuntu:38221/ ... Pid: 20339 Connections: * topic: /rosout * to: /rosout * direction: outbound * transport: TCPROS * topic: /tf * to: /amcl * direction: outbound * transport: INTRAPROCESS * topic: /clock * to: /gazebo (http://ubuntu:40085/) * direction: inbound * transport: TCPROS * topic: /tf * to: /amcl (http://ubuntu:38221/) * direction: inbound * transport: INTRAPROCESS * topic: /tf * to: /robotstatepublisher (http://ubuntu:33029/) * direction: inbound * transport: TCPROS * topic: /tf * to: /gazebo (http://ubuntu:40085/) * direction: inbound * transport: TCPROS * topic: /tfstatic * to: /robotstatepublisher (http://ubuntu:33029/) * direction: inbound * transport: TCPROS * topic: /scan * to: /gazebo (http://ubuntu:40085/) * direction: inbound * transport: TCPROS * topic: /map * to: /mapserver_1537203380314611704 (http://ubuntu:33768/) * direction: inbound * transport: TCPROS

user@ubuntu:~$

I tried outputting the /clock values as well, and I see nothing partiulcarly wrong there (except maybe that time seems to start at 1000seconds... go figure)

And indeed, when i try to view the tf tree with rosrun tf view_frames => the link between map and odom is missing, whereas i expect amcl to publish it.

I'm guessing that amcl is either not receiving /scan events and filtering them all (no laser scan received for 34139472 seconds feels a lot like none were ever received)=> therefore published no map->odom tf.

while increasing the verbosity of amcl from default info to debug (*), i see those debug messages, but i have no clue what they mean

[DEBUG] [1537204573.964568814, 3913.317000000]: MessageFilter [target=odom ]: Removed oldest message because buffer is full, count now 100 (frame_id=sensor_laser, stamp=3908.290000)
[DEBUG] [1537204573.964899783, 3913.317000000]: MessageFilter [target=odom ]: Added message in frame sensor_laser at time 3913.294, count now 100
[DEBUG] [1537204574.025497198, 3913.368000000]: MessageFilter [target=odom ]: Removed oldest message because buffer is full, count now 100 (frame_id=sensor_laser, stamp=3908.340000)
[DEBUG] [1537204574.025600379, 3913.368000000]: MessageFilter [target=odom ]: Added message in frame sensor_laser at time 3913.344, count now 100
[DEBUG] [1537204574.049464305, 3913.388000000]: Incoming queue was full for topic "/clock". Discarded oldest message (current queue size [0])
[DEBUG] [1537204574.054565708, 3913.392000000]: Incoming queue was full for topic "/clock". Discarded oldest message (current queue size [0])
[DEBUG] [1537204574.066972159, 3913.403000000]: Incoming queue was full for topic "/clock". Discarded oldest message (current queue size [0])
[DEBUG] [1537204574.086864841, 3913.420000000]: MessageFilter [target=odom ]: Removed oldest message because buffer is full, count now 100 (frame_id=sensor_laser, stamp=3908.390000)
[DEBUG] [1537204574.086959735, 3913.420000000]: MessageFilter [target=odom ]: Added message in frame sensor_laser at time 3913.393, count now 100
[DEBUG] [1537204574.133658368, 3913.453000000]: MessageFilter [target=odom ]: Removed oldest message because buffer is full, count now 100 (frame_id=sensor_laser, stamp=3908.440000)
[DEBUG] [1537204574.133732163, 3913.453000000]: MessageFilter [target=odom ]: Added message in frame sensor_laser at time 3913.442, count now 100
[DEBUG] [1537204574.182417016, 3913.491000000]: Incoming queue was full for topic "/clock". Discarded oldest message (current queue size [0])

(*) if someone knows how to default to debug so that i can see what's going on as the amcl node starts => plz let me know)

some environment parameters that may apply

user@ubuntu:~$ printenv | grep -i ros
ROSROOT=/opt/ros/kinetic/share/ros
ROSPACKAGEPATH=/home/user/catkinws/src:/opt/ros/kinetic/share
ROSMASTERURI=http://localhost:11311
ROSVERSION=1
LDLIBRARYPATH=/home/user/catkinws/devel/lib:/opt/ros/kinetic/lib:/opt/ros/kinetic/lib/x8664-linux-gnu
PATH=/home/user/bin:/home/user/.local/bin:/opt/ros/kinetic/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
ROSLISPPACKAGEDIRECTORIES=/home/user/catkinws/devel/share/common-lisp
ROSDISTRO=kinetic
PYTHONPATH=/home/user/catkinws/devel/lib/python2.7/dist-packages:/opt/ros/kinetic/lib/python2.7/dist-packages
PKGCONFIGPATH=/home/user/catkinws/devel/lib/pkgconfig:/opt/ros/kinetic/lib/pkgconfig:/opt/ros/kinetic/lib/x8664-linux-gnu/pkgconfig
CMAKEPREFIXPATH=/home/user/catkinws/devel:/opt/ros/kinetic
ROSETC_DIR=/opt/ros/kinetic/etc/ros
user@ubuntu:~$

How can I get rid of the No laser scan received (and thus no pose updates have been published) for xxxx seconds ?

<node name="map_server" pkg="map_server" type="map_server" args="$(arg map_file)">
    <param name="frame_id" value="/map"/>
</node>

  <arg name="map_file" default="$(find mnwlk3r_simulation)/maps/fablab_sim.yaml"/>
  <node name="map_server" pkg="map_server" type="map_server" args="$(arg map_file)">
    <param name="frame_id" value="map"/>