Publicações

Moita, P.P., Cardoso, J.B. e Valido, A.J. (2009), “Optimal Control of Systems to Impact with Preview Control”, Proceedings of the 8th World Congress on Structural and Multidisciplinary Optimization (WCSMO-8), 1-5 Junho, LNEC, Lisboa, Portugal

A control sensitivity analysis and multicriteria optimization formulation is derived for mechanical systems. A bound formulation is applied to handle the multicriteria problem. This formulation is implemented in an interactive optimum design code and it is applied to optimize impact protection systems. Preview control, where the isolation system starts responding to the impact before the application of this impact, is studied. The limiting isolation capacity of the systems is investigated. Comparison is made between systems with and without preview control. Damping and stiffness characteristics as well as control forces are considered as design variables. The design space is included into the control space by considering the design variables as control variables not depending on time. By using time integrals through all the derivations, design and control problems are unified. For treating preview control problems, free-time domain interval is considered. A unit time interval is mapped onto the original time interval, then treating free-time and fixed-time problems in a unified way. The dynamic response of the systems and its sensitivity are discretized via space-time finite elements. The equations of motion and the sensitivity equations are integrated at-once as it is typical for the static response. This way, displacement, velocity or acceleration control conditions can be imposed easily at any point in time. Also, adjoint system response is obtained without needing primary response memorization. Mathematical programming is used for the optimal control process.

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