Path Planning: Differential Dynamic Programming and Model Predictive Path Integral Control on VTOL Aircraft

This paper explores two optimal control approaches, widely used in robotics, to establish
their viability as real-time trajectory planners for vehicle configurations envisioned for the
emerging aviation sector of Urban Air Mobility (UAM). Differential Dynamic Programming
(DDP) enables planning over highly nonlinear dynamics using second-order approximations
along a nominal trajectory, and displays quadratic convergence to a local solution. Model
Predictive Path Integral (MPPI) is a stochastic sampling-based algorithm that can optimize
for general cost criteria, including potentially highly nonlinear formulations, and supports
parallel computation through the use of modern GPU hardware. In this work, DDP and MPPI
were implemented using model predictive control (MPC), and the results indicate they are able
to successfully transition the aircraft over different flight envelopes and generate trajectories
unique to UAM vehicles.