Assessment and Optimisation of Target Acquisition using SAR Seekers on Manoeuvrable Re-Entry Vehicles

Assessment and Optimisation of Target Acquisition using SAR Seekers on Manoeuvrable Re-Entry Vehicles

Olberts, Ernst (TU Delft Aerospace Engineering)

Naeije, M.C. (graduation committee)
Halswijk, Wouter (mentor)
Heiligers, M.J.C. (graduation committee)

Delft University of Technology

Aerospace Engineering

2022-02-25

In this thesis, the achievable performance and limitations of a Synthetic Aperture Radar (SAR) seeker on an Anti-Ship Ballistic Missile (ASBM) for a set of parameters has been investigated. This was achieved by modelling the dynamics of an ASBM and the constraints related to the acquisition requirements of a maritime surface target in the "Generation and Improvement Algorithm for Nonlinear Trajectories" (GIANT) optimisation tool provided by TNO. The angular velocities of the ASBM were set as the control variables for the optimal control problem where the objectives were set to the minimisation and maximisation of the exposure time and vertical end velocity of the missile and the minimisation of the required time for creating one SAR image by the SAR seeker.

Three experiments were carried out to investigate the influences for different initial conditions and resolution constraints on the optimised trajectory. In the first experiment, the trajectory was optimised for initial reentry conditions that are representative for typical ASBMs. The target was placed at the location that would match the uncorrected ballistic flight impact location of the ASBM. This allowed to compare and visualise the optimised manoeuvres of the ASBM relative to its ballistic flight trajectory. In the second experiment, the target was placed at the same location, but the initial re-entry conditions were optimised by GIANT, that provided the optimal trajectory. In the last experiment, the constraints related to the resolution of the target were lowered to analyse the maximum performance of the system.

The experiments show that a larger initial squint angle of the re-entry position of the ASBM improves the overall performance. This is because a larger squint angle allowed the missile to obtain a larger seeker look angle during the SAR phase while performing minimal manoeuvres during the re-entry phase. This permitted the dwell time of the SAR seeker and the exposure time of the missile to be as short as possible, while the missile’s vertical end velocity could be maximised. It was also shown that a ground range and crossrange resolution of 1.60 m could be achieved for an average dwell time of 0.1170 s. For better resolutions, the bandwidth of the SAR seeker appeared to be the limiting factor of the system for the chosen set of parameters.

Synthetic Aperture Radar
SAR
ASBM
Re-entry vehicle
Optimisation
Target Detection

http://resolver.tudelft.nl/uuid:98b4f465-1b26-48d8-90d7-53f773095f36

Student theses

master thesis

© 2022 Ernst Olberts