meirela's profile - activity

I wish to adjust the priority of cmd_vel_mux
For this purpose I've located some .YAML files for understanding the syntax.

• name: "Safe reactive controller"
  topic: "safety_controller"
  timeout: 0.2
  priority: 10
• name: "Keyboard operation"
  topic: "keyboard_teleop"
  timeout: 0.2
  priority: 7

I can't figure out what is the exact meaning of these fields - name/topic/timeout/priority.
Of course "name" is a name... But in which namespace? Where do I set this namespace?
"timeout" is a measure of time, guessing - idle time while dealing with the callback, but what units? (second/milliseconds/minutes)
Priority - which is high, which is low? What is the maximum number of priorities available?
Topic - same as name. I do not know any of these topics, they are not available when listing the current topics (rostopic list), so I guess it is also another namespace (?)

I followed kobuki's write your own controller tutorial and it seems going well, up to the stage where I wanted to test it.
I launched roslaunch kobuki_node minimal.launch followed by roslaunch kobuki_controller_tutorial bump_blink_app.launch --screen, and received the following error:

<blink>SUMMARY

PARAMETERS
* /rosdistro: indigo
* /rosversion: 1.11.20

NODES / bump_blink_controller (nodelet/nodelet)

auto-starting new master process[master]: started with pid [22106] ROS_MASTER_URI=http://localhost:11311

setting /run_id to c4c4caac-6525-11e6-b6da-408d5c56557f process[rosout-1]: started with pid [22119] started core service [/rosout] process[bump_blink_controller-2]: started with pid [22122] [bump_blink_controller-2] process has died [pid 22122, exit code 255, cmd /opt/ros/indigo/lib/nodelet/nodelet load kobuki_controller_tutorial/BumpBlinkControllerNodelet mobile_base_nodelet_manager bump_blink_controller/events/bumper:=mobile_base/events/bumper bump_blink_controller/commands/led1:=mobile_base/commands/led1 __name:=bump_blink_controller __log:=/home/cvil/.ros/log/c4c4caac-6525-11e6-b6da-408d5c56557f/bump_blink_controller-2.log]. log file: /home/cvil/.ros/log/c4c4caac-6525-11e6-b6da-408d5c56557f/bump_blink_controller-2*.log </blink>

I've tried rebuilding it a couple of times, it didn't help... I am also new to nodelets, so it might be connected to the problem.

I am trying to implement a "controller" for turtlebot
Specifically, I wish to build a unit that subscribes to multiple topics, relevant to to motion control (goal, path, object detection, keyop, etc) that can affect the motion decision making.

For example - I get a path plan to follow, while getting a keyop command, while reading a range sensor that triggers the "stop or else you'd hit that obstacle" bit. Now, I wish to control this information - some of it needs to be discarded, some of it should be ignored for now (but not discarded) and some of it needs some processing.

The problems I get are as follows: 1.Due to the fact that callbacks are asynchronous, I need to make sure all the information is processed in a correct priority. 2. I need to save the information that was ignored for later processing. 3. I need to save the state of the system

I only can think of global state variables and global stacks for dealing with this, but I was hoping that a thing like message_filter is available for this purpose.

I've been traveling around ROS' navigation stack, looking for the path correction code and I couldn't find it. I am using a kobuki iClebo's TurtleBot platform, along with kinect instead of laser scan.

I am pretty new to robotics and ROS, so I might need to understand first:
-There is the global planner (let's say A-star/Djikstra in my case) which is responsible for the Global Path
-There is the local planner (DWA/base_local_planner) which, alongside with the obstacle updates to the map by /scan topic, is responsible for obstacle avoidance and hopefully path correction (?)
-There is the move_base which I think acts as a "manager" for both of the above

Now, I couldn't find anywhere in those three the part that is responsible for path correction - the procedure of understanding where you are (localization), understanding where you were suppose to be (given by one of the planners) and giving control commands in order to close the gap between the two.

As I've came to the conclusion that kobuki's iClebo TurtleBot's odometry is not accurate at all (as expected), I'd like to implement a vision and odometry based control system that will make sure that my robot goes where it should.

I first wanted to see what ROS has to offer. After installing all of TurtleBot's navigation packages, I've set it on AMCL for localization and it gave me nice results. Unfortunately, I've been trying to find this piece of code for a long time now and I cannot... I came across move_base.cpp, dwa_planner.cpp, carrot_planner.cpp and couldn't find it there.

(I am aware that there are different levels of control - global, local, obstacle avoidance, safety control etc, but I just can't figure out which one does the localization feedback that I am looking for.)

Can someone point out "the way" to find this piece of code, or something similar? Doesn't have to be C++ btw.