Re: [Java-player-users] VFH

[Radu B. R. <ru...@in...>]

Hello Steffen,

On Tue, Aug 30, 2005 at 07:40:38AM +0200, Steffen Jaensch wrote:
> Hi,
> 
> Problem 1:
> 
> I'm using the vfh driver with the PositionInterface. How do I determine when
> the robot has reached its goal?
> 
> I've already tried to use getXSpeed and getYSpeed of the PositionInterface
> and to do busy waiting until the robot stops. However, this doesn't work
> satisfactorily, because it needs a very long delay (around one second)
> before I can use the speed information without taking the risk that it is
> not updated. Furthermore, busy waiting blocks my system unnecessarily.  

One second sounds a bit too much. Are you using the threaded mode?

> In order to get access to the position device at index 0 I simply do: 
> ppd     = playerClient.requestInterfacePosition(0, 'a');
> 
> To get access to vfh which runs at index 3, however, it does not suffice to
> request the PositionInterface at index 3, but I have to do the request three
> times. The first call returns position:1 (which does not exist), the second
> returns position:2 and finally the third call returns the desired
> PositionInterface for vfh. This is independend of what indices I speficy in
> the request method.
>  
> vfh     = playerClient.requestInterfacePosition(3, 'a'); 
> vfh     = playerClient.requestInterfacePosition(3, 'a');
> vfh     = playerClient.requestInterfacePosition(3, 'a');
> 
> Is it a bug or do I do something wrong?

Unfortunately, it is a bug. It has been on my "to fix" list for too long
now. I will do it asap.

> Many thanks,
> Steffen.

Cheers,
Radu.
--
| Radu Bogdan Rusu | http://www.rbrusu.com
| Intelligent Autonomous Systems Group
| Technische Universitaet Muenchen