Three-dimensional atmospheric entry problem using method of matchedasymptotic expansions

A composite solution consisting of an outer solution, an inner solution, and a common solution is obtained. The outer solution arises from the gravitationally dominant region, whereas the aerodynamically dominant region contributes to the inner solution. The common solution accounts for the overlap between the outer and inner regions. In contrast to previous work, this simplified methodology yields explicit analytical expressions for various compounds of the composite solution without resorting to any type of transcendental equation that can be solved only by numerical methods. The present method is application for obtained autonomous guides and control strategies for a variety of aerospace vehicles     

Fuel-optimal trajectories of aeroassisted orbital transfer withplane change

The fuel-optimal control problem arising in noncoplanar orbital transfer employing aeroassist technology is addressed. The mission involves the transfer from high Earth orbit to low Earth orbit with plane change. The complete maneuver consists of a deorbit impulse to inject a vehicle from a circular orbit to an elliptic orbit for atmospheric entry, a boost impulse at the exit from the atmosphere for the vehicle to attain a desired orbital altitude, and a reorbit impulse to circularize the path of the vehicle. In order to minimize the total fuel consumption, a performance index is chosen as the sum of the deorbit, boost, and reorbit impulses. The application of optimization principles leads to a nonlinear, two-point, boundary value problem, which is solved by a multiple shooting method     

Neighboring optimal guidance for aeroassisted orbital transfer

A neighboring optimal guidance scheme for a nonlinear dynamic system is devised with stochastic inputs and perfect measurements as applicable to fuel optimal control of an aeroassisted orbital transfer vehicle. For the deterministic nonlinear dynamic system describing the atmospheric maneuver, a nominal trajectory is determined. Then, taking modeling uncertainties into account, a linear, stochastic, neighboring optimal guidance scheme is devised. Assuming the additive character of the stochastic effects, the optimal trajectory is approximated as the sum of the deterministic nominal trajectory and the stochastic neighboring optimal solution. Numerical results are presented for a typical aeroassisted orbital transfer vehicle