Comments on "Time optimal feedback control for small disturbances"

The problem in the above-mentioned short paper is almost identical to the one considered earlier by the present author and, in fact, a special version of it. This note elaborates on this close relation between the results of the two papers

Linear-quadratic stochastic pursuit-evasion games

A linear-quadratic differential game in which the system state is affected by disturbance and both players have access to different measurements is solved. The problem is first converted to an optimization problem in infinite-dimensional state space and then solved using standard techniques. For convenience, “L2-white noise” instead of “Wiener process” setup is used

Minimum thrust levels for spinning drag-free satellites = Niveaux minimums de la force motrice pour des satellites rotatoires sans résistance = Minimum triebkraftniveaus für rotierende wiederstandsfreie satelliten

A drag-free satellite, which contains an internal unsupported proof mass, is shielded from external forces such as solar pressure. Thrustors force the satellite to follow the proof mass and hence the satellite follows an almost purely gravitational orbit. The dominant internal disturbing force is the mass attraction of the satellite on the proof mass. Spinning the satellite reduces this force and it has been investigated what the size of the thrustors must be in this case. This size is much smaller than originally thought. Its impact on some other features is shown

Regional allocation of investment as a hierarchical optimization problem

A new formulation is given for the well-known problem of investment allocation between regions in the framework of a planning model. The case of a dual economy with a Cobb-Douglas production function is worked out in detail with an illustrative numerical example. The corresponding problem for an industrial economy with income disparity between two regions is also discussed

Time-optimal control of multivariable systems near the origin

This article deals with bang-bang solutions of linear time-optimal control problems. Linear multivariable systems are considered which have one or more control components. It is shown in which way the control components act together to make the system achieve the ultimate aim (namely, the origin in the state space) as quickly as possible. The theory only applies to initial positions sufficiently near the origin. Criteria are given which give the number of switches per control component.\ud \ud Asymptotic dependences of the switching times and the final time on the distance of the initial position from the origin are established. The theory provides a numerical procedure to calculate the time-optimal control. These calculations are very simple. Basic to the proof of these results is a generalized implicit function theorem due to Artin (Ref. 1)

Role determination in an aerial dogfight

A coplanar aerial dogfight is analyzed by assuming constant, not necessarily identical, speeds and individual maximum turning rates and lethal ranges. A combatant (A) is assumed to be victorious when his opponent (B) has been maneuvered into a relative position within A's lethal range and in the direction of A's velocity.\ud \ud Three variables are required to define the instantaneous “state” of the game, namely the relative position (2) and the angle (1) between their velocities. A computer program has been constructed to divide the 3-dimensional region of possible initial (and subsequent) states into regions corresponding to victory by one or the other combatant, and, if the faster combatant has the smaller lethal range, a “no contest” region corresponding to escape by the faster combatant.\ud \ud The critical separating surface (or surfaces) is composed of a number of pieces corresponding to initial conditions leading either to simultaneous kill or to “near miss” situations of one type or another. Optimal play is defined in the immediate neighborhood of the entire separating surface, guaranteeing victory (or escape) to one combatant or the other, depending on location on one side or the other of the separating surface

Numerical approaches to linear—quadratic differential games with imperfect observations

A two-person pursuit—evasion stochastic differential game with state and measurements corrupted by noises is considered. In an earlier paper the problem was reformulated and solved in an infinite-dimensional-state space, and the existence of saddle-point solutions under certain conditions was proved. The present paper provides a numerical solution for the resulting continuous-time integro-partial differential equations. This solution scheme is based on the utilization of the second guessing technique, and, in spite of the fact that a complicated set of integro-partial differential equations have to be solved, the numerical results seem plausible and promising