  Operating in the presence of strong adverse forces is a particularly
challenging problem in field robotics. In most robotic operations where the
robot is not firmly grounded, such as aerial, surface, and underwater, minimal
external forces are assumed as the standard operating procedures. The first
action for operating in the presence of non-trivial forces is modeling the
forces and their effect on the robots motion. In this work an Autonomous
Surface Vehicle (ASV), operating on lakes and rivers with varying winds and
currents, collects wind and current measurements with an inexpensive
custom-made sensor suite setup, and generates a model of the force field. The
modeling process takes into account depth, wind, and current measurements along
with the ASVs trajectory from GPS. In this work, we propose a method for an ASV
to build an environmental force map by integrating in a Gaussian Process the
wind, depth, and current measurements gathered at the surface. We run extensive
experimental field trials for our approach on real Jetyak ASVs. Experimental
results from different locations validate the proposed modeling approach.
