# issue while building a map

hi i am trying to build a map using slam i am using arduino with ROS. i am using arduino duo and it publish imu data and encoder and subscribe to cmd vel know every thing is good all the odometer data is good but some time while building the map robot move in the map few cm to left or right more than real life sometimes he correct his position on the map and some times not. drive method is diff drive. i test the encoder if i move 1 meter there is no error at all. and imu data is correct without any error some problem occur some time is:

WARN] [WallTime: 1485180236.120524] Serial Port read returned short (expected 312 bytes, received 147 instead).
[WARN] [WallTime: 1485180236.120981] Serial Port read failure:
[INFO] [WallTime: 1485180236.121363] Packet Failed :  Failed to read msg data
[INFO] [WallTime: 1485180236.121683] msg len is 312


this not happen all the time just some time.

but this happen alot :

scan Matching Failed, using odometry. Likelihood=-754.114
lp:-0.826714 -0.201986 -0.497758
op:-0.564566 -0.17674 -2.21354
Scan Matching Failed, using odometry. Likelihood=-4266.67
lp:-0.826714 -0.201986 -0.497758
op:-0.564566 -0.17674 -2.21354
Scan Matching Failed, using odometry. Likelihood=-4266.67

now i have question in the main launch the following line



now is this line is important or not ? and if its important how exactly i can adjust this parameter after args= i try to search how to adjust it and i dont know now. Is this parameter cuse the problem above or not.

for the information sometime i can build the map with relatively small error not noticeable but its not happen all the time. i need a way or solution that help for building the map without any issue like this. i use ROS indigo . thanks i hope any one can help.

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Could you please use the Preformatted Text button (the one with 101010 on it) to properly format console copy/pasted text (ie: the error messages and launch file snippets)? That would make things much easier to read. Thanks.