Re: [Playerstage-users] help on rotate robot by a given degree

[kingwinter <kin...@gm...>]

hi, Rich:
Sorry for my fault. I have found the "goto" driver. It hasn't been listed on
the online manual but exist in the instatllation.

Best Regards
Kingwinter


kingwinter wrote:
> 
> hi, Rich:
> Thanks very much for quick reply. In my understand, I can use either vfh
> or snd proxies to drive the robot locally. I don't want to use global map.
> Is there any example code to use vfh under the installation?
> 
> Is there a driver called "goto"? I didn't find it. I guess you just mean
> the group of driver such as vfh and snd. 
> 
> Best Regards
> Kingwinter
> 
> Rich Mattes-2 wrote:
>> 
>> In order to do closed-loop position control, *something* has to be
>> constantly reading your current position, comparing it with your desired
>> position, and issuing velocity commands accordingly.  Whether your client
>> program is doing it or a driver is doing it is immaterial, the "waste of
>> computation time" has to take place somewhere.  The Player server itself
>> offers none of this functionality, its role is just to manage drivers and
>> pass messages between them.
>> 
>> The "goto" driver provides this functionality, as do the local planning
>> drivers (vfh, nd, snd, etc.)  The local planning drivers have the added
>> benefit of providing local obstacle avoidance, but they're all
>> essentially
>> running a constant loop that checks the robot's current position (and
>> sometimes whether there are obstacles in the immediate area area),
>> compares
>> it with the desired robot position, and reacts accordingly.
>> 
>> Using a "planner" driver isn't always the right answer.  There are two
>> classes of planners: the above local path planners, and global planners.
>> Global path planners, like wavefront, don't necessarily do position
>> control
>> at all.  They simply take your current position and your desired
>> position,
>> put them on a map and look for the best path between the two points while
>> avoiding obstacles.  They then provide a list of waypoints along the path
>> (a
>> series of (x,y,yaw) positions) through the Planner interface.  Once you
>> have
>> those waypoints you still need to have some kind of low-level controller,
>> be
>> it a local path planner or a simple proportional controller like goto, to
>> run a control loop that determines which velocities are required to get
>> to
>> the desired position. vfh uses a planner interface even though it's a
>> local
>> path planner, but it doesn't support the formation of a list of waypoints
>> along the way to the goal.  It just provides useful information like its
>> current position, where it's trying to go, and a "done" field that
>> indicates
>> its reached the goal position.
>> 
>> Rich
>> 
>> 
>>> -----Original Message-----
>>> From: kingwinter [mailto:kin...@gm...]
>>> Sent: Wednesday, September 29, 2010 11:15 AM
>>> To: pla...@li...
>>> Subject: [Playerstage-users] help on rotate robot by a given degree
>>> 
>>> 
>>> hello
>>> I am looking for some solutions that I can send a turning angle
>>> (relative to
>>> present heading) to the robot and it can then rotate to that direction
>>> only
>>> using odometry without a map.
>>> I know there is a solution of using setspeed() function, but I have to
>>> regularly check the robot heading can control the rotating duration.
>>> The
>>> problem is that I have to poll the status and waste computation time. I
>>> also
>>> have to check in high fresh rate to avoid overshooting. Is there any
>>> other
>>> way to send this turning angle to the player server and it will do it
>>> and
>>> send back a notice once it done.
>>> 
>>> Another solution I knew is using planner proxy but it requires a map. I
>>> cannot use it because I want the robot run in a dynamic environment.
>>> 
>>> Is there any other solutions?
>>> 
>>> BTW, I am using P3DX pioneer robot now.
>>> 
>>> thanks
>>> kingwinter
>>> --
>>> View this message in context: http://old.nabble.com/help-on-rotate-
>>> robot-by-a-given-degree-tp29839628p29839628.html
>>> Sent from the playerstage-users mailing list archive at Nabble.com.
>>> 
>>> 
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>> 
>> 
>> ------------------------------------------------------------------------------
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>> 
> 
> 

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