[ros-users] Pioneer 3dx in ROS

[David Feil-Seifer]

I wrote the node, but a while ago, so I can't be sure, but Ithink that
I sent a "pulse" message every 1s to keep that watchdog from kicking
in. However, by default it is turned off. Try setting the "pulse"
parameter to 1.

-Dave

On Fri, Apr 23, 2010 at 8:24 AM, Brian Gerkey <gerkey at willowgarage.com> wrote:
> It's been a long time since I used a Pioneer, and I haven't looked at
> the node that you're using, so this is shooting in the dark:
>
> If I recall correctly, the microcontroller implements a watchdog that
> will stop the motors if it hasn't heard a velocity command over the
> serial line after a certain amount of time.  If you send commands too
> slowly, the watchdog would kick in between commands, causing the robot
> to move a bit, halt, move a bit, halt, etc. I believe that the
> watchdog is configurable, or at least can be turned on or off, which
> might account for the different in behavior between your robots.
>
> Something to try is to make the node resend the last received velocity
> to the robot at a relatively high rate (10Hz should be enough).  Of
> course, the node should then implement its own watchdog, which would
> send zero velocities if it hasn't received a command via ROS after
> some time.
>
>        brian.
>
> On Fri, Apr 23, 2010 at 6:56 AM, Tucker Hermans <thermans at cc.gatech.edu> wrote:
>> Dan,
>> Without being able to investigate your setup further, the only thing I can
>> think is that the commands being sent over the serial connection are either
>> experiencing high latency or are being sent to infrequently, so that the
>> velocity commands sent to the microcontroller are far enough apart that you
>> get the stuttering effect.
>> I tried reproducing this by setting a very high time (30s as opposed to 2s)
>> to resend velocity commands but this had no effect.  Are you seeing
>> statements from the p2os node of the form "new speed [0.25, 0.0]
>> (timestamp)" and "setting vel: [0.25,0.0]".  If not what kind of debug
>> output are you seeing on the node?
>> -Tucker
>>
>> On Thu, Apr 22, 2010 at 12:31 PM, Dan Lazewatsky <lazewatskyd at cse.wustl.edu>
>> wrote:
>>>
>>> I just tried out a few things from your pioneer_control package and I get
>>> the same behavior I was seeing before.
>>>
>>> -Dan
>>>
>>> On 4/21/10 7:13 PM, Dan Lazewatsky wrote:
>>>
>>> Hi Tucker,
>>> I think that should be enough to get me going.
>>>
>>> Thanks!
>>> -Dan
>>>
>>> On 4/21/10 6:57 PM, Tucker Hermans wrote:
>>>
>>> Hi Dan,
>>> I send the MotorState command of 4 and have no problems.
>>> I have a teleop keyboard port which I use for communicating with the p3dx
>>> that you can find
>>> here: github.com/trhermans/AffLearning/tree/master/pioneer_control/
>>> Note: the launch file is setup for a p3dx with a PTZ connected to an
>>> onboard computer and uses the probe camera driver to get the video stream.
>>> I have only been testing the changes to the p2os package on a p3dx with an
>>> onboard computer, I don't think this should have any issues, but it could.
>>> Let me know if the keyboard operation gives the same problems you have now
>>> and I'll try and help debug it.
>>> -Tucker
>>>
>>> On Wed, Apr 21, 2010 at 7:49 PM, Dan Lazewatsky
>>> <lazewatskyd at cse.wustl.edu> wrote:
>>>>
>>>> Hi all -
>>>> I know this has been discussed here a bit, but not in much detail.
>>>> We have a Pioneer3dx that we'd like to get up and running again. I
>>>> downloaded and compiled the p2os package which seems to be able to
>>>> successfully connect and communicate with the robot using a serial to
>>>> USB adapter. However, I'm having trouble getting the motors to do
>>>> anything sensible. The robot's motor self-test looks like it works fine,
>>>> but sending cmd_vel, all I can get is extremely slow, jerky movement
>>>> forward or backwards (no turning). I enabled the motors with:
>>>>
>>>> rostopic pub cmd_motor_state -1 p2os/MotorState 1 (I also tried 4
>>>> instead of 1 which was mentioned in a previous discussion)
>>>>
>>>> This feels like a communication problem between the motor commands p2os
>>>> is sending and the robot, but I don't know what's going on. Any ideas?
>>>>
>>>> Thanks,
>>>> -Dan
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