QUASI-STATIC OPTIMAL ACTUATOR PLACEMENT WITH MINIMUM WORST-CASE DISTORTION CRITERION

The problem of placing actuators optimally in truss structures for qua sistatic shape control is considered, Optimal actuator placement in la rge truss structures is a formidable task due to the combinatorial nat ure of the problem, In this paper we use and compare the performances of several heuristic search techniques to determine their effectivenes s in solving this design problem. The selected methods are simulated a nnealing, exhaustive single-point substitution, and single location it erative minimization, a sequential minimization technique presented he rein, The optimality criterion is the worst case distortion after corr ection. This worst case value of a performance measure is obtained thr ough a constrained min-max procedure, An ideal actuator concept is emp loyed to determine limits on the optimal criterion value, which is the n used also to evaluate the number of actuators needed for given level s of correction, The procedures just discussed are performed on repres entative trusses, Results show that heuristics can handle the optimiza tion problem since the number of function calls grows linearly with th e size of the problem and not in a combinatorial fashion, typical in s uch cases. The different algorithms exhibit similar performances; howe ver, exhaustive single point substitution requires a significantly hig her computational effort, The applicability of the lower limit is inve stigated, and in most cases there is good agreement with the optimizat ion results.