A Pattern Search Algorithm for Feedback Control System Parameter Optimization.
IOWA UNIV IOWA CITY DEPT OF MECHANICAL ENGINEERING
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The problem of parameter optimization for the purpose of synthesis and design of multi-loop feedback control systems is considered. A flexible performance index, based on performance specifications such as rise time, settling time, peak overshoot and bandwidth is developed and adapted to a modified version of Rosenbrocks pattern search algorithm. Modifications of Rosenbrocks method include scaling of parameters to make coordinate-orthogonalization more effective and employing variable step sizes at the beginning of each new stage, the steps being a function of previous failures and successes. The efficiency of each stage is thus improved and the sensitivity to initial estimates of step sizes is reduced. A stopping criterion for the search based on a given number of consecutive stages with no improvement of the performance index within the precision of the computer is shown to be effective. Calculation of sensitivity numbers and desired performance specifications around the optimal point is included to give a feel for system behavior near optimal conditions. The IBM360 Continuous System Modeling Program CSMP is employed, permitting system simulation directly from a block diagram. Author
- Theoretical Mathematics