  We develop an algorithm to control an underactuated unmanned surface vehicle
(USV) using kinodynamic motion planning with funnel control (KDF). KDF has two
key components: motion planning used to generate trajectories with respect to
kinodynamic constraints, and funnel control, also referred to as prescribed
performance control, which enables trajectory tracking in the presence of
uncertain dynamics and disturbances. We extend prescribed performance control
to address the challenges posed by underactuation and control-input saturation
present on the USV. The proposed scheme guarantees stability under user-defined
prescribed performance functions where model parameters and exogenous
disturbances are unknown. Furthermore, we present an optimization problem to
obtain smooth, collision-free trajectories while respecting kinodynamic
constraints. We deploy the algorithm on a USV and verify its efficiency in
real-world open-water experiments.
