ACTIVE CONTROL OF ALP WITH IMPROVED PERFORMANCE-FUNCTION

Conventional optimal control theories usually deal with performance fu nction that involves only structural displacement and velocity. This p aper presents an algorithm for the linear active control by considerin g also the structural acceleration in the performance function without bringing in the actuator dynamics. The linear optimal control law, th us achieved, is implemented to control the peak displacement response of a 180.5 m tall articulated leg platform (ALP) under the random sea state. Both controlled and uncontrolled responses of the ALP are obtai ned by an iterative frequency domain technique which duly considers al l the nonlinearities present in the system. The controlled responses a re compared with those obtained by the conventional linear feedback co ntrol strategy in order to investigate the efficiency of the proposed algorithm. Numerical results indicate that the proposed algorithm perf orms better than the conventional control strategy. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.