No description available.

No description available.

No description available.

Optimal intercept trajectories for a boost-sustain-coast medium-range air-to-air missile are synthesized using optimal control theory. Optimality in time/range/energy at intercept of a target is the main objective. Attainable sets and their boundaries are obtained and used to generate optimal intercept points in a three-dimensional scenario. A three-phase closed-loop guidance scheme is used to generate an efficient guidance law against a maneuvering target. In the present study, target maneuvers are restricted to the horizontal plane. An initial boost-phase with near-optimal guidance in the presence of active control constraints and thrust switches is simulated. Target maneuvers are neglected during this phase. A new method of gain evaluation is detailed. A midcourse guidance scheme with neighboring guidance, transversal comparisons, and chasing center-of-attainability of target to augment performance is studied. Modifications in terminal guidance using proportional navigation, such as chasing the center-of-attainability of target, altitude shaping, and drag-resolution schemes are used to attempt better performance at intercept. A composite guidance strategy using a combination of neighboring guidance and proportional navigation for the midcourse guidance is introduced. The excellent performance of this guidance strategy and the improvement in storage requirements for on-board use make it a very special scheme. / Ph. D.

No description available.

Optimal midcourse guidance is examined for an air-to-air missile featuring boost-coast-sustain propulsion. A vertical plane, point-mass model is studied with load factor as a control variable. Time-range-energy optimal trajectories are computed, open-loop, via the usual necessary conditions and a multiple-shooting algorithm. A requirement on terminal velocity magnitude is examined for its effect on firing range. Next, a study of the optimal midcourse guidance problem with reduced-order models is presented. The models under study, in addition to the point-mass model, are: - Singularly perturbed model with y as fast variable; - Point mass model with approximation of the induced-drag; - Energy model. One of the major results in this study is that the reduced-order models are not accurate enough to approximate the optimal trajectories and so are of limited use as reference trajectories in an on-board scheme. Thus, optimal trajectories, computed by using the point-mass model, are selected as the reference trajectories for a closed-loop guidance scheme. Finally, an approach to on-board real-time calculations for an optimal guidance approximation is derived. Extremal fields and neighboring extremal theory ideas are used together with pre-calculated Euler solutions to construct a closed-loop guidance algorithm. The method is applied to the midcourse guidance of an air-to-air missile and was found to perform quite well. / Ph. D.

To regain operation of a Minuteman Missile guidance computer, a ferromagnetic film was sprayed onto a previously inoperable memory disk after the original coating was removed using paint remover. The coating was then polished down to provide a smooth and uniform film, 1'he permanent data required for the clock and sector channels was determined from an operable Minuteman computer. 1-his information was then recorded on the memory disk using the write heads which were part of the complete memory unit. Digital electronics using integrated circuits provided theand generated the recording data _or the memory write heads. A "memory check" program verified the uniformity of the repaired memory by alternately writing "0' s" and "1' s" on each bit location and then reading and comparing the numbers to "0's" and "l's".Ball State UniversityMuncie, IN 47306

Bibliography: p. 196-200. / M.I.T. Project DSR 76094. Contract no. NOW-66-0178-d.

The field of guided projectile research has continually grown over the past several decades. Guided projectiles, typically encompassing bullets, mortars, and artillery shells, incorporate some sort of guidance and control mechanism to generate trajectory alterations. This serves to increase accuracy and decrease collateral damage. Control mechanisms for smart weapons must be able to withstand extreme acceleration loads at launch while remain simple for cost and reliability reasons. One type of control mechanism utilizes controllable internal translating masses (ITM's) that oscillate within the projectile to generate control forces. Several techniques for using internal translating masses for smart weapon flight control purposes are explored here. Specifically, the use of ITM's as direct control mechanisms, as a means to increase control authority, and as a means to protect the smart weapons sensor suite are examined. It is first shown that oscillating a mass orthogonal to the projectile axis of symmetry generates reasonable control force in statically-stable rounds. Trade studies examine the impact of mass size, mass offset from the center of gravity, and reductions in static stability on control authority. Then, the topic of static margin control through mass center modification is explored. This is accomplished by translating a mass in flight along the projectile axis of symmetry. Results show that this system allows for greater control authority and reduced throw-off error at launch. Another study, aimed at examining shock reduction potential at launch rather than static margin alteration, also considers ITM movement along the projectile centerline. In these studies, the ITM is comprised of sensitive electronic sensors, and is configured as a first-order damper during launch. Trade study results show that although the mechanism cannot substantially reduce the magnitude of launch loads, it is successful at dampening harmful structural vibrations typically experienced after muzzle exit. Finally, an active control system is developed for the ITM control mechanism using sliding mode methodology. Example cases and Monte Carlo simulations incorporating model uncertainties and sensor errors show that ITM control of projectiles can substantially reduce dispersion error. Furthermore, the novel sliding mode control law is shown to be highly robust to feedback disturbances. In a final study, combined ITM-canard control of projectiles is explored, concluding that ITM mechanisms can serve as a useful supplement in increasing the efficiency of currently-deployed control mechanisms.