BFL package for GPS navigation?

I have found your site searching a solutions for my outdoor robot
lawn-mover. I am still working on conceptual things - one (a hardest) of them is positioning.
I will use 3 identical GPS [+/-2 metre precission] devices displaced in regular triangle - about 10
cm from each other, giving each second a global position. I will read
simulateous this data , and compute them to get estimated position by
weighting values by other reads (rotation speed from tyres, turning angle).

The question is - is there a posibility to use this BFL package to
process 2-Dimensional GPS position data from 3 pre-distanced sources
to get triangle centred point with precision 10cm (the GPS gives
accuracy only 2.2Metre) ?

Sorry, if my idea is not well formulated or absurd, i am not so good
with statistic and math.

With best regards,
Gunars Rodins.