bobliao's profile - activity

Hi, everyone! I have a application that require the robot following a point in the indoor environment with variant obstacles. the robot is aware of the target point relative position (x, y). the robot is equipped with 3D camera. How can the robot move from the current pose to the target position(x,y), actually here we set a problem that what action can reduce the relative value (x,y) without a known map.

i have used camera_calibration to generate my desired calibration info . but ,how can i apply this data to my application. i can see the original calibration info by

" rostopic echo /usb_cam/camera_info".
and how can i find the location of the "/usb_cam/camera_info",

then edit it by replacing by the previous calibration.

in a word,where does my camera driver store its calibration information ? thanks!!!

I have no robot, so I must build one piece by piece. I use differential drivers ,each with a encoder.And each encoder can output two channels signal :A,B.

I can read channel A and B to aquire the speed and direction of a motor through Arduino device.

But how can I integrate the signal from the two encoders with the topic of /odom with the lowest level device Arduino? If this is done by Arduino ,I doubt the ability of an 8-bit processor. so is there any relevent reference about it?

i have check the detail of msg /odom:

rosmsg show nav_msgs/Odometry 
std_msgs/Header header
  uint32 seq
  time stamp
  string frame_id
string child_frame_id
geometry_msgs/PoseWithCovariance pose
  geometry_msgs/Pose pose
    geometry_msgs/Point position
      float64 x
      float64 y
      float64 z
    geometry_msgs/Quaternion orientation
      float64 x
      float64 y
      float64 z
      float64 w
  float64[36] covariance
geometry_msgs/TwistWithCovariance twist
  geometry_msgs/Twist twist
    geometry_msgs/Vector3 linear
      float64 x
      float64 y
      float64 z
    geometry_msgs/Vector3 angular
      float64 x
      float64 y
      float64 z
  float64[36] covariance

thank you very much!

I follow the instruction : Ubuntu 12.04 (Precise)

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu precise main" > /etc/apt/sources.list.d/ros-latest.list'

Set up your keys

   wget http://packages.ros.org/ros.key -O - | sudo apt-key add -

sudo apt-get update

then ,that is this :

Hit http://packages.ros.org precise Release Get:1 http://packages.ros.org precise/main i386 Packages [1,641 kB] Ign http://packages.ros.org precise/main TranslationIndex
Hit http://packages.ros.org precise/main Translation-en Ign http://packages.ros.org precise/main Translation-en_US Fetched 1 B in 3s (0 B/s) W: Failed to fetch gzip:/var/lib/apt/lists/partial/packages.ros.org_ros_ubuntu_dists_precise_main_binary-i386_Packages Hash Sum mismatch

E: Some index files failed to download. They have been ignored, or old ones used instead.

then ,I type:

sudo apt-get install ros-groovy-desktop-fullat
that is this:
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package ros-groovy-desktop-full

I then check the directory:

bob@bob-robot:/etc/apt/sources.list.d$ ls ros-latest.list

I have search the similar answer,it may be the source problem , so how to solve it? many thanks ,I am waiting the answer...

This phonemenon seldom occurs,but i have seen it several times in the past months. my operations are followings:

1. Start my ubuntu,then open a terminal
2. I type "roscore",however nothing appears...

after i wait about several minutes .i see the following,and i go on my waiting :

... logging to /home/bobliao/.ros/log/49c47ac0-1117-11e2-976a-74ea3a7e2629/roslaunch-bob-r-2600.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

after 10 minutes , it prints the error info ,and that's an error of MASTER_URI configuration problem. but why this error make the terminal so slow?there must be something else,as ordinary it will print the error immediately.

i am only working on the single mode,all the ros nodes are on the same machine. here , i paste related lines of my .bashrc file :

export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/fuerte/

export ROS_WORKSPACE=~/fuerte

source /opt/ros/fuerte/setup.bash

export ROS_MASTER_URI=http://192.168.1.101:11311

export ROS_HOSTNAME=192.168.1.101

my network configuration:on PC,i use a wireless card,connected to a router.and when i run my PC,the IP may change when the PC is running ,i think this lead to the failure of network. but it cost much time to print error,makes me confusd.

thank you for your detail reply,Shanmugasivam Pillai!

I have kill all nodes by :rosnode kill -a however, when I type: rostopic list a list of topics are there ,so Can I remove the topics created before?

waiting for answers,thanks!

I have searched the solution for my problem,however i am still puzzled. below is my problem: 1.I download the examples from the Arduino IDE on my Uno 238P

2.execute :roscore , rosrun rosserial_python serial_node.py /dev/ttyACM0,

output:

[INFO] [WallTime: 1344165710.415424] [0.000000] ROS Serial Python Node

[INFO] [WallTime: 1344165710.434731] [0.000000] Connected on /dev/ttyACM0 at 57600 baud

But, when i list the topics: /rosout /rosout_agg

and service list: /rosout/get_loggers /rosout/set_logger_level

i have found that others terminal will show :

[INFO] [WallTime: 1342164886.822488] ROS Serial Python Node

[INFO] [WallTime: 1342164886.825278] Connected on /dev/ttyACM0 at 57600 baud

[INFO] [WallTime: 1342164888.953740] Note: publish buffer size is 512 bytes

[INFO] [WallTime: 1342164888.974499] Starting service client, waiting for service 't

so ,how to solve it ?thanks!

I have met the same problem.And I also can not solve it .

In my catkin package ,if I import "move_base_msgs", then "ImportError:No module named move_base_msgs".

I know it is because it has not be catkinized,so I want to know when it will be completed.

My catkin is thirsty for this module.

I type: sudo apt-get update,then:

Ign http://extras.ubuntu.com precise/main TranslationIndex                                                       
Get:101 http://extras.ubuntu.com precise/main amd64 Packages [1,273 kB]                                          
Ign http://ppa.launchpad.net precise/main Translation-en_US                                                      
Get:102 http://extras.ubuntu.com precise/main i386 Packages [1,274 kB]                                           
Ign http://ppa.launchpad.net precise/main Translation-en                                                         
Ign http://packages.ros.org precise/main Translation-en                                                          
Get:103 http://extras.ubuntu.com precise/main Translation-en [893 kB]                                            
Ign http://extras.ubuntu.com precise/main Translation-en_US                                                      
Fetched 36.5 MB in 22s (1,656 kB/s)                                                                              
W: Failed to fetch bzip2:/var/lib/apt/lists/partial/ppa.launchpad.net_iheartengineering_ros-support_ubuntu_dists_precise_main_binary-amd64_Packages  Hash Sum mismatch

W: Failed to fetch bzip2:/var/lib/apt/lists/partial/ppa.launchpad.net_iheartengineering_ros-support_ubuntu_dists_precise_main_binary-i386_Packages  Hash Sum mismatch

W: Failed to fetch gzip:/var/lib/apt/lists/partial/packages.ros.org_ros_ubuntu_dists_precise_main_binary-amd64_Packages  Hash Sum mismatch

W: Failed to fetch gzip:/var/lib/apt/lists/partial/packages.ros.org_ros_ubuntu_dists_precise_main_binary-i386_Packages  Hash Sum mismatch

W: Failed to fetch bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_source_Sources  Hash Sum mismatch

W: Failed to fetch bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_binary-amd64_Packages  Hash Sum mismatch

W: Failed to fetch bzip2:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_precise_main_binary-i386_Packages  Hash Sum mismatch

E: Some index files failed to download. They have been ignored, or old ones used instead.

I have tried to remove the /var/lib/apt,and apt-get clean, but still . btw , I installed groovy by the ubuntu dist with turtlebot version.

it doesn't work.

No,I try it ,but it doesn't work , I have also reinstall the ubuntu three times ,but failed

I follow the instruction: 1.on Ubuntu 11.10 (Oneiric)

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu oneiric main" > /etc/apt/sources.list.d/ros-latest.list'

2.Set up my keys:

wget http://packages.ros.org/ros.key -O - | sudo apt-key add -

3.sudo apt-get update

However ,it doesn't work:

Get:75 http://mirror.bjtu.edu.cn oneiric-security/restricted Translation-en [978 B]
Get:76 http://mirror.bjtu.edu.cn oneiric-security/universe Translation-en [45.9 kB]
Fetched 19.7 MB in 11s (1,657 kB/s)                                            
W: Failed to fetch gzip:/var/lib/apt/lists/partial/packages.ros.org_ros_ubuntu_dists_oneiric_main_binary-i386_Packages  Hash Sum mismatch

I have try to clean the /var/lib/apt/lists,but it doesn't work.

I installed fuerte several months ago,and this time I even can't install the ros!

This problem have bothered me a month....