  We design new navigation strategies for travel time optimization of
microscopic self-propelled particles in complex and noisy environments. In
contrast to strategies relying on the results of optimal control theory, these
protocols allow for semi-autonomous navigation as they do not require control
over the microswimmer motion via external feedback loops. Although the
strategies we propose rely on simple principles, they show arrival time
statistics strikingly similar to those obtained from stochastic optimal control
theory, as well as performances that are robust to environmental changes and
strong fluctuations. These features, as well as their applicability to more
general optimization problems, make these strategies promising candidates for
the realization of optimized semi-autonomous navigation.
