[Pioneer-users] How to get the true relative distance between robots?

[Reed Hedges]

Hi, all robots have some error in position estimated by encoders 
(odometry), but this is especially true with the AT which is a skid 
steer robot, and the wheels must slip over the ground for it to rotate 
(by comparison, the DX has more acurate odometric position estimate 
because the wheels only slip sometimes, and in small amounts). 
MobileSim has some artificial error applied uniformly, but on a real 
robot it may be greater, and will vary depending on how it moves and 
over what kind of surfaces.

If your AT has a gyro, then it will automatically improve the heading 
estimate but won't make it perfect.

But to have the most accurate positioning you need some kind of 
localization based on a sensor or other external reference.

You could try slowing the robot down, especially when rotating.  Other 
people on this list may have found some speed parameters that might have 
helped a bit. Anyone have any advice?

Reed


wjxnet_126 wrote:
>  hello, everyone!
>  
> Recentrly the following problem bothers me. Using a control law, i want two robots have some desired distance and relative 
> angle.  The control law proves to be corrent under MobileSim.  While operating on our P3-AT robots, which has no GPS installed, their final distance and relative angle seen by eyes are far from the desired one, even if the Printf function prints them to to be the desired one.  I use ArNetworking to transfer a leader robot's states like X,Y,Th,Vel to the follower robot. The follower robot's own states are read by
>  
>  FollowerRobotInfo.X=myRobot->getRawEncoderPose().getX();
>  FollowerRobotInfo.Y=myRobot->getRawEncoderPose().getY();
>  FollowerRobotInfo.Th=myRobot->getRawEncoderPose().getTh();
>  FollowerRobotInfo.Vel=myRobot->getVel();
>  FollowerRobotInfo.RotVel=myRobot->getRotVel();
>  
> I am wondering maybe some errors occur on states readings, could you please tell me how to impove the precision of robots' states reading.  Thanks a lot!
>  
>  
> Jianxin Wu
>  
>  
>  
> 
> 
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