Trajectory Design of Re-entry Vehicles using combined Pigeon Inspired Optimization and Orthogonal Collocation method

Abstract

This paper presents an orthogonal collocation based entry trajectory solution strategy using Pigeon Inspired Optimization (PIO). PIO is a swarm algorithm based on the homing behavior of pigeons. For the unpowered re-entry vehicle, bank angle modulation is considered as the primary control with a predefined nominal angle of attack profile. In this approach, bank angle is approximated using a higher order polynomial. This control variable is discretized at Chebyshev Lobatto collocation points. The value of bank angle at these points is obtained using PIO algorithm. The terminal constraints of entry trajectory are part of the objective function. After generating the entry trajectory referred to as reference trajectory, Linear Quadratic Regulator (LQR) control is used to track the reference trajectory for dispersions in the initial states at entry interface. Advantages of PIO algorithm are that it does not require an initial guess and that inequality constraints can be incorporated. This method is demonstrated by applying it to Common Aero Vehicle (CAV-H) with high lift to drag ratio.