Fast Trajectory Optimization For Advanced Space Vehicle

Nowadays, a number of developed countries have launched many programmes about Advanced Space Vehicles(ASV), which include Reusable Launch Vehicle, Crew Return Vehicle, Space Operation Vehicle, Military Space Plane, Space Maneuver Vehicle et al., ground on space resource exploitation and strategic interests. The guidance and control methods should enable the ASV to accomplish fully autonomous and adaptive flight, a key problem is to achieve the optimal controls quickly. However, determining how to find the best controls of an ASV so that it is able to safely reach Terminal Area Energy Management (TAEM) or go into specified orbit involves the solution of a two-point boundary value problem. This problem, which is considered to be difficult, is traditionally solved on the ground rather than onboard. The optimal controls are found regardless of computing time by most of algorithms, which can meet requirements of traditional shuttle guidance. That is, traditional trajectory optimization algorithms can not perform this fast trajectory optimization tasks. The main works of this dissertation are focused on the fast ASV trajectory optimization, including:Fast optimization of three-dimensional reentry trajectoryTraditional trajectory optimization algorithms cannot perform this fast optimization task. In this dissertation, a new hypothesis is introduced according to the features of three-dimensional constrained reentry trajectory of ASV. The dynamics and kinematics equations of motion are divided into two sets and only one of those is involved in iterations of optimization algorithm, and this simplification reduces the computation labor greatly. Different from other optimization algorithms, firstly, the algorithm generates a reentry corridor according to all common inequality constraints and quasi-equilibrium glide conditions. Then, a normal trajectory can be achieved based on range constraints within the corridor and a normal control variable (the bank angle) will be obtained by utilizing the normal trajectory and quasi-equilibrium glide conditions. Next, the Conjugate-Gradient Method is applied to optimize another control variable (the angle of attack). All above methods and operationes accelerate the convergence of optimization iteration greatly. The simulation shows that this methodology is able to generate a feasible reentry trajectory of about 2000 seconds flight time in about 10 seconds on the desktop computer.Fast optimization of three-dimensional launch trajectoryThe dissertation focuses on fast generation and optimization of three-dimensional ascent trajectory for ASV, which is one of fundamental research work. Firstly, the set of dynamics and kinematics equations of motion is simplified according to the features of three-dimensional constrained ascent trajectory of ASV, and this simplification reduces the computation labor greatly. Then, the trajectory optimal...