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2015-05-14 07:28:00 -0500 answered a question Prevent topics in custom node from being prefixed by node name

So, I changed how I was searching in ROS answers, and came across this answered question! This solves my problem. I was using my private nodehandle for subscribing instead of the normal nodehandle...

http://answers.ros.org/question/11728...

2015-05-14 07:13:41 -0500 asked a question Prevent topics in custom node from being prefixed by node name

I wrote out a custom PID position controller for a turtlebot. Basically, it sends velocity to command for the straight-line path to a target. I'm having an annoying issue, though. Every topic that the controller subscribes to gets prefixed by the node name in ROS. The name of my node is "BotPID," as is the name of my class. The following three lines are contained in the constructor:

poseSubscriber = nh_private.subscribe("goal/pose", 10,&BotPID::poseCallback,this);
poseDesiredSubscriber = nh_private.subscribe("robot/pose", 10, &BotPID::poseDesiredCallback,this);
//advertise twist publisher
twistPublisher = nh_private.advertise<geometry_msgs::Twist>("cmd_vel_mux/input/teleop", 10);

Annoyingly, when I run the node, the following topics show up in ROS:

/BotPID/robot/pose
/BotPID/cmd_vel_mux/input/teleop
/BotPID/goal/pose

Is there any way in my node to prevent these topics from being prefixed by the node name without adding a "/" before the name of the file?

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2015-02-06 13:37:35 -0500 commented question Laser_ortho_projector transformation problem

I'm dealing with the same problem! Any help here would be appreciated.

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2014-04-04 08:22:36 -0500 asked a question QGroundControl with mavlink_ros

Quick question: Is there an easy way to allow both mavlink_ros and QGroundControl to connect to the same /dev/ttyUSB0 port? I have mavlink_ros running to collect IMU data off of an ArduPilot 2.6, but I also need to connect to the same port on QGroundControl. I don't need to send any commands over mavlink_ros, just receive data.

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2014-03-27 13:46:35 -0500 asked a question Spoofing GPS on ardupilot using gmapping

I've been working on creating a quadrotor that can autonomously navigate an obstacle course. Thus far, I have a neato xv-11 lidar and IMU data that goes into laser_scan_matcher_node. Out of laser_scan_matcher comes the base_link to odom transform. This transform feeds into slam_gmapping along with the scan data to build a map of the local environment. Here is a link to an rqt_graph of what I have running so far: www.dropbox.com/s/7scqst4brhwl7lh/dia...

My question is this: Does anyone know of a good way to take the Pose2d estimate from laser_scan_matcher and send it to the ardupilot through the GPS port? I want to convince the ardupilot that it has a good GPS lock using the positional estimate. I believe the APM looks for NMEA messages.

I am completely at a loss as to how I should go about this. Any help would be very appreciated.

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2014-03-17 07:05:52 -0500 asked a question Getting linear acceleration from mavlink_ros (APM2.6)

Hello,

I am working on a team that hopes to implement a SLAM algorithm on a quadrotor using an xv-11 LIDAR and IMU data from an APM2.6. So far, I have the scan data coming in over a serial to bluetooth adapter, and I have mavlink_ros running to pull in the IMU data from ROS at 25Hz. I had to change some parameters on the arudpilot using QGroundControl to get this 25Hz rate. I was hoping to combine the scans with the IMU and use laser_scan_matcher to provide odometry for gmapping. However, when I run "rostopic echo fcu/imu" (the imu data coming in from the ardupilot), I get the following:

 header: 
  seq: 4206
  stamp: 
    secs: 1395075512
    nsecs: 568997836
  frame_id: fcu
orientation: 
  x: 0.0453795122836
  y: -0.0137595356653
  z: 0.00616009589894
  w: 0.998856059831
orientation_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
angular_velocity: 
  x: -0.00247164955363
  y: -0.000945815816522
  z: 0.000395094510168
angular_velocity_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
linear_acceleration: 
  x: 0.0
  y: -0.0
  z: -0.0
linear_acceleration_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

I have a couple questions: Are the covariance fields needed? Also, I assume laser_scan_matcher will be needing the linear_acceleration fields. Does anyone know how to get the linear accelerations from the APM? Is there a parameter on the APM that I need to change to get this?

Thank you for any help in this regard.