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2020-10-18 21:51:25 -0500 answered a question hector_quadrotor installation in ROS melodic

You can try sudo apt install ros-melodic-driver-base. But I didn't have this error compelling from source. I got packag

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2016-10-27 06:52:16 -0500 commented answer Running ROS across multiple machine

Yeah, I think it's better to set ip for ROS_IP and hostname for ROS_HOSTNAME. But both can be used in practice since I've been setting ip for ROS_HOSTNAME and it has been working very well.:)

2016-10-27 06:47:48 -0500 commented answer Running ROS across multiple machine

From your error message, I think ROS_MASTER_URI is not set correctly. Maybe you start a new window of terminal without setting variables for the new terminal?

2016-10-27 06:42:14 -0500 answered a question Running ROS across multiple machine

On each machine, you should export ROS_MASTER_URI = http:// master_ip:11311 and export ROS_HOSTNAME = this_machine_ip. For each terminal, these two environment variables should be set, so it's recomanded that you write them in .bashrc .
The former variable is used to tell this machine where the master(roscore) is. The latter variable is used to tell master where this machine is for registering node.

xx_ip above should be replaced by your ip conf.Hope this answer helps.

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2016-10-20 09:03:04 -0500 answered a question How to create round shape models in Stage

Well, I guess it's impossible. I tried to draw a picture. The corresponding round obstacle in stage is made of a vast number of rectangular obstacles of different sizes. So I think round obstacle is not supported in stage.

2016-10-20 08:55:25 -0500 asked a question Any quadrotor simulation package in ROS Kinetic?

Hi, I've been workiing with quadrotor simulation in gazebo and ROS indigo utilizing hector_quadrotor package. Now I have changed my ROS to kinetic and Ubuntu to 16.04.
However, hector_quadrotor can be no longer utilized due to various compile erros. The main reason I find out is that gazebo 7 no longer support some old APIs which hector_quadrotor calls. I tried to solve these compilation problems but failed.
Could you please tell me some other simulation package available in ROS kinetic with gazebo? Thanks for your advice.

2016-10-11 02:35:27 -0500 asked a question How to create round shape models in Stage

Hi, I'm working with robot swarm simulation in Stage and I need some round shape models as obstacles.But after searching I only find out how to make polygon models by defining each vertex.
Is there any method to make round shape models in Stage? Drawing a picture with round obstacles as a map may be feasible but that would be lack of extendability as my map scale may vary.

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2016-09-14 14:28:03 -0500 marked best answer robot formation in ROS

Hi, I'm going to work with ground mobile robot formation in ROS, using turtlebot to do some experiments in simulator like stage. However, there's a tough problem.

The velocity command in ROS is made up of linear velocity and angular velocity while a vast number of formation algorithms result in velocity in 2D vector. Is there any method to make a translation? What if the algorithm generates target point to each robot? How to generate ROS velocity,namely Twist, to make diff-drive robots like turtlebot arrive in such points. I don't think using navigation stack is a good idea.

I'd appreaciate it if anyone can give me some advice or some related package in ROS.

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2016-04-26 07:02:19 -0500 asked a question Stage ros velocity publish rate

Hi, I am working with some simulation issues in Stage ROS. I want to reduce the publish rate of each robot's pose topic, e.g. robot_0/base_pose_ground_truth, robot_1/base_pose_ground_truth, etc. due to my limited network bandwidth. With the number of robots increased the network is becoming congested. Is there any way to change or namely, reduce the publish rate of such stage topics so that I can release more network resources? I'd appreicate it if you can give me some advice. :)

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2016-03-31 19:22:33 -0500 commented answer Python import: rosrun works well but roslaunch reports error

Thanks a lot! It works well for me. :)

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2016-03-30 20:47:57 -0500 asked a question Python import: rosrun works well but roslaunch reports error

Hi, I'm writing some rospy nodes recently and some import errors ocur when I utilize roslaunch to start my node.

a.py
1 import sys
2 sys.path.append("..")
3 from middle_abstraction.function_unit import FunctionUnit

ImportError: No module named middle_abstraction.function_unit

The file is organized as following

package
    scripts
       basic_support
          a.py
      middle_abstraction
          function_unit.py

When I cd to basic_support and run python a.py, everthing is working well as well as when I utilize rosrun pkg a.py. But when I utilize roslaunch, this error ocurs.

I have written one setup.py file in my pkg folder:

## ! DO NOT MANUALLY INVOKE THIS setup.py, USE CATKIN INSTEAD

from distutils.core import setup
from catkin_pkg.python_setup import generate_distutils_setup

# fetch values from package.xml
setup_args = generate_distutils_setup(
    packages=['multi_robot_patrol'],#my pkg name
    package_dir={'': 'src'},
    requires=['std_msgs', 'rospy', 'message_filters', 'gps_common', 'sensor_msgs']
)

setup(**setup_args)

I'm really confused that rosrun works pretty well but roslaunch reports import error. I'd appreciate it if anyone can help me.

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2016-03-27 19:38:14 -0500 commented answer Any holonomic robots available in Stage?

Thanks! That's actually what I need. :)

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2016-03-25 22:23:16 -0500 asked a question Any holonomic robots available in Stage?

Hi~I'm going to work with some robot formation methods in ROS. I want to do my experiments in Stage. However, the algorithm generates velocity vector (x,y)rather than (linear,angular) which is used by many nonholonomic robots like turtlebot. It's a bit tough to deal with diff-drive robot, which is not focused in my research.
So what I want is some kinds of ideal mobile robots in Stage to do experiments for my formation method. But I'm new to stage and I've used only turtlebot in Stage before. I'd appreciate it if anyone can help me with some available kinds of robots in Stage or some useful packages in ROS. Thanks a lot!

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