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An extended optimal guidance law with terminal miss distance and impact angle constrains is derived. The guidance law is obtained as the solution of a linear quadratic optimal control problem with the goal function weighted by a power of the time-to-go. Based on the analytical expression for the change of guidance command with time and the adjoint system analysis method,the command characteristics and dimensionless miss distance of guidance law are analyzed. The result shows that the acceleration command of guidance law can be converged into zero in the final time of guidance,which may create a good situation for terminal angle of attack control. A design principle for selection of guidance law gain is discussed. Finally,according to the requirements of engineering application,the methods on calculating the guidance initial condition and maximal required acceleration are given. The effectiveness and practicality of the guidance law are demonstrated through simulation. [ABSTRACT FROM AUTHOR]

In order to analyze the miss distance caused by the matching performance between pitch and roll control channels, a principle model about BTT guidance was built base on the BTT-90 command calculation logic and proportional navigation guidance law. The model included the simplified control system model and nonlinear model about guidance command calculation and aerodynamic translation. Taking the velocity pointing error and target maneuvering as the analysis conditions, the influence on the miss distance was analyzed and the STT control was compared also. The simulation results show that the total aerodynamic of system is determined by the slower autopilot within the pitch and roll control channels when BTT control used in the end guidance. It is the essential condition for the miss-distance converging to zero, that the guidance time is 10 times more than the aerodynamic time constant of the control system. To insure the high guidance accuracy, the response rate of the roll control channel should be faster than that of the pitch control channel. And only the response rate of the roll control channel is 5 times faster than that of pitch control channel, the miss distance of BTT will be close to that of STT. [ABSTRACT FROM AUTHOR]

Follow the characteristics of multi-constraints reentry guidance for reusable launch vehicles (RLV), a new method of reentry guidance algorithm is put forward based on estimation of the density. With the technique of parameter-discriminated, the algorithm would find out the current condition of aerosphere. Further more, the algorithm could generate reasonable bank angle profiles with the consideration of path constraints such as heat rate flow, normal load and dynamic pressure. The predicted terminal location is then compared to normal condition, and the mismatch would be used to generate the magnitude of bank angle. Combining with lateral bank reversals, the on-line design of reentry guidance is completed finally. Simulation results demonstrate the effectiveness of the algorithm on achieving desired final conditions for different reentry initial conditions and atmospheric uncertainty. [ABSTRACT FROM AUTHOR]

The computational method of range estimate is presented to deal with the problem that the accuracy of position is too low to satisfy calculating the time-to-go because the pure INS has worked for long time without GPS. The messengers used by method include sight line angle from image seeker, relative position and altitude from INS. Under typical measuring errors, the influence of sampling frequency on estimation accuracy was analyzed. The engineering application scheme and time-to-go calculation strategy were given. The simulation results show that the accuracy of the range estimate is well enough to be used in engineering. [ABSTRACT FROM AUTHOR]

The trigonometric function method is usually used to transform the guidance command from Cartesian coordinates into polar coordinates on non-circular cross section missile, but it is easy to cause roll angle command singularity. Based on the theory of generation and conversion of guidance command, the basic cause of generating control singularity was analyzed with the measures of partial differential coefficient and contour line. A strategy to control singularity of roll angle command was presented by partitioning different control areas. In the singularity control area, the smooth control command was adopted to avoid the occurrence of singularity. The result shows that the strategy could greatly eliminate the influence of control singularity of bank-to-turn on the control precision. Simulation results show that this method is reasonable and could be used in engineering. [ABSTRACT FROM AUTHOR]

A new maneuvering-deceleration guidance algorithm based on atmosphere estimation is presented for the precise guidance and velocity control of hypersonic reentry vehicle. The maneuvering-deceleration guidance command is composed of optimal guidance command and deceleration command. The optimal guidance command is obtained by guidance law with position and impact angle constraints. Sinusoid maneuvering-deceleration command is used to minimize the position disturbance caused by deceleration. And the parameters of maneuvering command are produced from mismatch between terminal predicted velocity and nominal-velocity by numerical integration method. The atmosphere parameter identification technology is also used to improve the prediction precision. The simulation results show that the maneuvering-deceleration guidance algorithm has strong robustness against uncertain conditions; it can accomplish the integrated design of precise guidance and deceleration control efficiently. [ABSTRACT FROM AUTHOR]

A new solving method called local accurate search was proposed for the calculation of allowable attack area of air-to-surface missiles. Compared with traditional method, the local accurate search can search the area online and reduce the time of search with the required precision. The new method employs the local search to find an accurate result by combining the traditional flight range table with the model calculation method, which meets the requirements for attacking of moving target and fast calculation. [ABSTRACT FROM AUTHOR]