  We apply optimal control theory to a model of a polar active fluid (the
Toner-Tu model), with the objective of driving the system into particular
emergent dynamical behaviors or programming switching between states on demand.
We use the effective self-propulsion speed as the control parameter (i.e. the
means of external actuation). We identify control protocols that achieve
outcomes such as relocating asters to targeted positions, forcing propagating
solitary waves to reorient to a particular direction, and switching between
stationary asters and propagating fronts. We analyze the solutions to identify
generic principles for controlling polar active fluids. Our findings have
implications for achieving spatiotemporal control of active polar systems in
experiments, particularly in vitro cytoskeletal systems. Additionally, this
research paves the way for leveraging optimal control methods to engineer the
structure and dynamics of active fluids more broadly.
