navigation stack SendingSimpleGoals Tutorial

asked 2011-03-18 03:09:50 -0500

avin111
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updated 2011-03-26 07:45:35 -0500

58457 ●128 ●550 ●526 http://www.ros.org/

Hi all, I am trying to run on our differential drive robot with the navigation stack.I am using cturtle 1.2.4.the tf transform in my setup is map->odom->base_link->base_laser.However When i am giving the initial pose using rviz to make the robot to be on map the odom frame is not moving with respect to the base_link.It is staying at the same place as before.However the laser frame is transforming properly.I am not able to give the goal to the robot.When i used sending goals through code the following error is showing "The base failed to move forward 1 meter for some reason".As far as i understand the localization is working fine.So where I am going wrong?Thanking you

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Is this a custom robot or are you using an existing driver to provide access to the robot itself (such as p2os or rosaria)?

Eric Perko ( 2011-03-18 03:16:08 -0500 )edit

no we have build the robot ourselves and also written the drivers.The drivers are working fine because we are able to operate it using joystick.

avin111 ( 2011-03-18 04:05:19 -0500 )edit

So you are using the code from http://www.ros.org/wiki/navigation/Tutorials/SendingSimpleGoals to send goals?

Eric Perko ( 2011-03-18 05:07:55 -0500 )edit

yes I am using the same code to send goals..

avin111 ( 2011-03-18 05:46:10 -0500 )edit

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answered 2011-03-26 07:46:53 -0500

tfoote

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With your updates to the question the error you are getting says that the move base action failed. Do you have 1 meter of free space in front of the robot? Try it with a smaller distance defined.

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i will try that and reply u back.Thank you for the suggestion..

avin111 ( 2011-03-27 20:29:54 -0500 )edit

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answered 2011-03-18 03:15:33 -0500

Eric Perko

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updated 2011-03-18 05:56:12 -0500

It sounds like perhaps your base_link->odom transform is not updating. Does the robot move in rviz if you joystick or push it around?

The Robot Setup tutorial has details on setting up an example odometry source.

A good sanity check for whether or not your odometry is working correctly is to joystick the robot around with the following rviz configuration:

 set the fixed_frame to odom
 set the decay_time on the laser scanner's topic to something very large (1000 or so should do)

If your odometry is working properly (and is accurate), you should get something that looks like a map of your environment. If you don't get anything like that, there is definitely a problem with your base_link->odom transform.

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i have tried moving using joystick .the odom frame is moving along with the base_link frame when i am using joystick.but when i am trying to give a goal in rviz it is not working.

avin111 ( 2011-03-18 03:38:43 -0500 )edit

@avin111: Since debugging the navigation stack will likely involve lots of back and forth, can you make sure to update the question to include all the extra info from this and the comment above (and any other future comments that add more info to the question)? This will keep things better organized

Eric Perko ( 2011-03-18 05:10:00 -0500 )edit

Since the Joystick works, can you check the output on /cmd_vel (or whatever you may have remapped the cmd_vel topic to) when the navigation stack is trying to execute a goal? Also, do you get any output in, say, rxconsole, from move_base when it "fails to move forward 1 meter"?

Eric Perko ( 2011-03-18 05:13:00 -0500 )edit

You say that the odom frame "moves with" the base link which is not what it's supposed to do. The odom frame is supposed to stay approximately stationary while the robot moves around. How are you computing your odom?

tfoote ( 2011-03-18 05:43:51 -0500 )edit

@tfoote i am computing my odom using encoders.As said before the odom frame is grouping into red lines when it is moving forward.even the robot moves along with this.

avin111 ( 2011-03-18 05:48:15 -0500 )edit

@avin111: @tfoote has a good point (that I missed when reading your comment). See REP 105 for details on the coordinate frames used: http://www.ros.org/reps/rep-0105.html . See update to answer for more debugging steps.

Eric Perko ( 2011-03-18 05:53:38 -0500 )edit

@eric i am getting a map which is looking somewhat like my environment...So my odom->base_link transform is correct?

avin111 ( 2011-03-18 06:36:07 -0500 )edit

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navigation stack SendingSimpleGoals Tutorial

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