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2015-03-18 16:37:31 -0500 commented answer Publishing to Initialpose Programmatically on Turtlebot Navigation

This code fragment stopped working...ROS is cruel

2015-03-18 16:36:53 -0500 commented answer Publishing to Initialpose Programmatically on Turtlebot Navigation

Hi Dan, thanks for your answer! I'm not sure if the publisher not starting up is the problem, because I do see the message coming out through rostopic echo. If the publisher were not up yet, I'd expect to not see any messages through rostopic echho

2015-03-18 14:26:03 -0500 answered a question Publishing to Initialpose Programmatically on Turtlebot Navigation

Interestingly, the code will work if I change to one of two things:

while not rospy.is_shutdown():  
        rospy.loginfo(pose)
        pub.publish(pose)
        rate.sleep()

or

pub.publish(pose)
rate.sleep()
pub.publish(pose)
rate.sleep()    
pub.publish(pose)
rate.sleep()

clearly there's some sort of strange time dependence here.

Anyone have an idea why this might be?

2015-03-18 13:18:49 -0500 asked a question Publishing to Initialpose Programmatically on Turtlebot Navigation

Hi,

I am trying to set the initial pose of the turtlebot programmatically, and to do so I publish to initial pose using some code. I am following what is done here: http://answers.ros.org/question/11463...

I can publish to initial pose, but the robot will not react. When I set a new nav goal, the robot will continue from its previously calculated pose. Here is what rostopic echo /initialpose looks like:

    header: 
  seq: 1
  stamp: 
    secs: 0
    nsecs: 0
  frame_id: map
pose: 
  pose: 
    position: 
      x: 100.0
      y: 102.0
      z: 0.0
    orientation: 
      x: 0.0
      y: 0.0
      z: 0.0267568523876
      w: 0.999641971333
  covariance: [0.25, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.25, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.06853891945200942]
---

One interesting thing is that that header here shows seq to be 1, when I never set it to be 1 in my code.

My publishing code looks like this:

def talker():
pub = rospy.Publisher('/initialpose', geometry_msgs.msg.PoseWithCovarianceStamped, queue_size=10)
rospy.init_node('talker', anonymous=True)
rate = rospy.Rate(1) # 10hz

pose = geometry_msgs.msg.PoseWithCovarianceStamped()
pose.header.frame_id = "map"
pose.pose.pose.position.x=100
pose.pose.pose.position.y=102
pose.pose.pose.position.z=0
pose.pose.covariance=[0.25, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.25, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.06853891945200942]
pose.pose.pose.orientation.z=0.0267568523876
pose.pose.pose.orientation.w=0.999641971333
    rospy.loginfo(pose)
    pub.publish(pose)
rospy.spin()

if __name__ == '__main__': try: talker() except rospy.ROSInterruptException: pass

Does anyone know what might be happening?

2015-03-18 13:10:43 -0500 answered a question Raspberry Pi 2 or Odroid U3 enough performance to run ROS and AR-Tag Pose Estimation?

Even though the raspberry pi might not be powerful enough to run the vision stuff on-board, it should be fairly easy to run it from the workstation. I was able to get the kinect kind-of working on the raspberry pi and publishing data.

2015-03-05 15:26:20 -0500 asked a question Transferring State Between Navigation Processes

I'm working on a project to enable load balancing across computers running ROS applications, specifically I way to move robot navigation processes from one desktop computer to another, so that if you have a couple of desktop computers, you can use these to control your robot, but not deal with your computer slowing down because it's running something like mapping or navigation, since the navigation process will hop to another machine.

This requires the process to transfer its state. Does anyone know how the navigation stack might transfer its state between instances? Thanks

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2015-03-05 14:53:45 -0500 answered a question TurtleBot with Cloud Computing

I've managed to get the gmapping program working on a remote computer because for me gmapping itself, let alone visualization with rviz, was slow. I edited the launch files of the gmapping so that it would not do 3dsensor.launch, then manually ran 3dsensor.launch on the netbook. This way as long as the netbook can handle the kinect data and the turtlebot drivers, it should be able to control the turtlebot. I'm working right now on getting the raspberry pi 2 to control the turtlebot in this way. One concern is the additional latency this creates, which I'm wondering if anyone knows how to measure.

2015-03-05 14:53:44 -0500 asked a question Measuring System Latency

I'm controlling a turtlebot, and would like to measure the latency of the system.

Specifically, I'd like to see how long between when a frame is taken on the connect, to when it is read by the subscriber in move_base, and then to when the cmd_vel corresponding to it is published.

Does anyone have an idea of how I might measure these times?

Thanks