Trajectory planning of dynamic systems, in near real time, is important for
aerospace systems, especially uncrewed air vehicles and launched munitions
. Trajectory plans that do not consider the governing dynamic equations, ap
plicable path, and actuator constraints may be unrealizable during executio
n. A trajectory planning scheme is proposed for a class of dynamic systems,
referred to as differentially hat systems. The planner is motivated from o
nline computations and is aimed to satisfy the state equations, path and ac
tuator constraints, and given initial and terminal constraints. The essence
of the approach is demonstrated by two examples: 1) a hardware implementat
ion on a spring-mass-damper system to demonstrate real-time capabilities du
ring pursuit and 2) trajectory planning of a planar vertical takeoff and la
nding aircraft to illustrate the application to nonlinear problems.