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2019-10-05 00:04:47 -0500 asked a question ROS node link can not find qt4::Gui

ROS node link can not find qt4::Gui Hi, when I compile my ROS workspace, it complained the following: /usr/bin/ld: cann

2019-09-16 03:16:26 -0500 received badge  Popular Question (source)
2019-09-15 23:05:45 -0500 answered a question How to stop a robocar

Anyone knows?

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2019-09-14 20:38:04 -0500 asked a question How to stop a robocar

How to stop a robocar Hi, I am building a ROS based robocar. It has an jetson TX2 which used a Ackermann node with speed

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2019-09-04 16:43:28 -0500 answered a question Sparkfun 9DOF_Razor_IMU Yaw angle not correct

Anyone knows?

2019-09-02 22:57:38 -0500 asked a question Sparkfun 9DOF_Razor_IMU Yaw angle not correct

Sparkfun 9DOF_Razor_IMU Yaw angle not correct Anyone using Spark fun 9DOF_Razor_IMUI? I have used the IMU on jetson tx2

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2019-08-19 15:01:18 -0500 marked best answer rviz can not send goal to move_base from another computer

Hi,

I am running a car-like robot. I have an move_base node with global/local planner, and I can send goal from rviz to move the car. Now, I want to run the rviz from another computer. Everything works fine, I can see the tf, laser scan etc in rviz. But when I sent the goal with "2D Nav Goal" in rviz from another computer, the car did not move. The car did not get the goal message either when I run "rostopic echo".

Why?

2019-08-19 14:59:59 -0500 marked best answer TF tree has two root node

Hi all,

I am building a MIT-RACECAR with ZED stereo camera and Yokuyo LiDar on it. When I visualized the /tf, it showed two trees:

One tree has 1)odom as root, then 2)base_link as second layer and then 3)Laser, Base_footprint, IMU as children of base_link

Another tree has 1)Map as root, then 2)ZED_center as second layer and then 3)ZED left camera and ZED right camera as children of ZED_Center.

I remember that tf can have only one tree, one root node. Then how can I combine the two trees into one?

Thanks,

2019-08-19 14:59:42 -0500 marked best answer Car-like robot navigation

Hi, I am building a MIT-Racecar, a so called "Car-like robot". I found a lot of features in current ROS navigation stack did not work on Car-like-robot. I am wondering if there is any existing navigation ROS software for car-like-robot.

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2019-08-07 02:09:47 -0500 marked best answer rospack can not find my plugin

Hi, I am following this tutorial http://wiki.ros.org/navigation/Tutori... and write a global planner plugin. my package is robocars, my class name is robocars::PathFollowingGlobalPlanner. Here is my package.xml:

<export>
    <!-- Other tools can request additional information be placed here -->
    <!-- <nav_core plugin="${prefix}/path_following_global_planner_plugin.xml" /
>-->
    <nav_core plugin="${prefix}/path_following_global_planner_plugin.xml" />
  </export>

And here is my path_following_global_planner_plugin.xml

<library path="lib/libpath_following_global_planner_lib">
  <class name="robocars/PathFollowingGlobalPlanner" type="robocars::PathFollowin
gGlobalPlanner" base_class_type="nav_core::BaseGlobalPlanner">
    <description>This is a global planner plugin by robocars project.</descripti
on>
  </class>
 </library>

PathFollowingGlobalPlanner class compiled fine. "rospack find robocars" can find my package. But when I run "rospack plugins --attrib=plugin nav_core", the plugin did not show up.

Why

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2019-06-20 15:56:01 -0500 asked a question Convert IMU message to world system

Convert IMU message to world system I have a question about the IMU message. Is the orientation quaternion from the mess

2019-06-20 15:24:01 -0500 answered a question Get Roll/Pitch/Yaw from IMU not correct

I am thinking may be the IMU orientation is related to the robot the IMU device attached to? Even the car rotated 90 deg

2019-06-20 10:19:28 -0500 commented question Get Roll/Pitch/Yaw from IMU not correct

This is what I used: static void toEulerAngle(const Quaterniond& q, double& roll, double& pitch, double&

2019-06-20 10:18:50 -0500 commented question Get Roll/Pitch/Yaw from IMU not correct

This is what I used: static void toEulerAngle(const Quaterniond& q, double& roll, double& pitch, double&

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2019-06-10 15:30:36 -0500 asked a question Joy package with PS4 controller on Jetson TX2

Joy package with PS4 controller on Jetson TX2 Can I run the Joy ROS package with PS4 controller on Jetson tx2? Could any

2019-06-10 01:33:08 -0500 asked a question Access i2c from my node, need superuser permission

Access i2c from my node, need superuser permission Hi, my robot uses Jetson tx2 and there is a segment LED linked to tx2

2019-06-10 01:32:18 -0500 asked a question Access i2c from a node, need sudo permission

Access i2c from a node, need sudo permission Hi, my robot uses Jetson tx2 and there is a segment LED linked to tx2 i2c.

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2019-06-07 00:44:22 -0500 edited question libi2c ros wrapper

libi2c ros wrapper I have a robocar running jetson tx2 and would like to attached a segment LED display (https://www.ama

2019-06-07 00:43:06 -0500 asked a question libi2c ros wrapper

libi2c ros wrapper I have a robocar running jetson tx2 and would like to attached a segment LED display (https://www.ama

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2019-05-22 15:25:11 -0500 marked best answer Hokuyo LiDAR misses scan

I am working on a robocar project. The car has Nvidia jetson TX2, LiDAR, camera, IMU, etc and the ROS node is started with 4 thread

ros::MultiThreadedSpinner spinner(4)
spinner.spin();

The LiDAR is Hokuyo UST-10LX. I used the following code to subscribe to the scan data:

_subScan = _nh.subscribe("/scan", 4, &scanCallback, this, ros::TransportHints().tcpNoDelay());

In the callback function, the car processes the scan to localize itself and then send out Ackermann drive command to move along a pre-defined path. Hokyyo UST-10LX is 40hz which provides very dense data for the car to run smoothly.

However, I did found that in some cases, my ROS node missed quite some scan frames. It could miss as many as 40 scans. So the car paused for about a second, did not know where to go since the callback function was not called.

My questions are:

  1. Why the scan frames were missed and callback funciton was not called?
  2. If this could happen, what is the best way to handle this? Since all my localization and drive code are inside the LiDAR callback, if I missed the scan, the car will stop.

Thanks,

2019-05-22 08:58:07 -0500 commented answer Hokuyo LiDAR misses scan

Thanks. What is the correct way to save the data...

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2019-05-22 00:45:47 -0500 answered a question Hokuyo LiDAR misses scan

I found the problem. In the scanCallback, for every LiDAR frame, the latest LiDAR, camera image, IMU, odom data was save

2019-05-21 15:34:58 -0500 asked a question Get Roll/Pitch/Yaw from IMU not correct

Get Roll/Pitch/Yaw from IMU not correct Hi, I have 2D robot with IMU. I am trying to extract the roll/pitch/yaw data fro

2019-05-21 13:31:00 -0500 commented question Hokuyo Laser Scan seq not continous

I have increase the queue size to 4, but still missing scans

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