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The linear parameter-varying framework for active vibration control of elastic kinetic structures
(2024)
Lightweight design is essential for preserving resources, and in addition, transformability can be beneficial for specific applications where multi-functionality is required. Multi-functionality contributes to saving resources by allowing multiple purposes to be served effectively and by allowing adaptation to changing needs. Elastic kinetics are a recent approach to design transformable lightweight structures with a stable transformation process, realized by elastic bending of structural members. Their lightweight and flexible design comes at the cost of increased sensitivity to static and dynamic disturbances. However, most of the current research concentrates on transformation principles instead of on disturbance mitigation. This research focuses on dynamic disturbance mitigation for transformable lightweight structures based on elastic kinetics using active control. The dynamic behavior of such structures is transformation state dependent due to geometric nonlinearities, which is not easily captured by linear time-invariant methods. For this reason, modeling and control design are performed in the linear parameter-varying (LPV) framework. Thereby, two distinct LPV modeling methodologies are investigated, one based on finite element models and another utilizing experimental system identification techniques. Furthermore, LPV control strategies are introduced, which allow to adapt to the varying structural dynamics encountered in elastic kinetics. To validate the efficacy of the modeling and control approaches, a physical demonstrator resembling a segment of an elastic kinetic roof structure is realized within a laboratory environment. This demonstrator structure is used for experimental studies to assess the accuracy and performance of the introduced methods. Utilizing experimental data from the demonstrator structure, a proposed LPV system identification methodology can be applied to derive separate LPV models for the bending and the torsional dynamics of the demonstrator structure. Based on the derived LPV models, a decoupled active vibration control for bending and torsional dynamics by means of an LPV output-feedback is designed. The designed control is implemented on a real-time environment, and its effectiveness is demonstrated experimentally for fixed and for varying operating conditions on the realized demonstrator structure.