Configuration of control system for damage tolerance of a tensegrity bridge

Abstract

Tensegrity structures are spatial, discrete and lightweight structures that are composed of struts in compression and pre-stressed cables. Stability is provided by the self-stress state between elements independently of external actions. Tensegrity structures are attractive due to their potential for deployability, ease of tuning and high precision control. Since tensegrity structures have highly coupled behavior, placement of actuators is a primary concern when designing active control systems. This study investigates the active control performance of cable members of a tensegrity bridge. The actuation efficiencies of cable members are evaluated through a multi-criteria approach. The configuration of the control system is thus identified through outranking candidate active members. A multi-objective damage tolerance strategy is then proposed and optimally directed control solutions are identified using stochastic search. Case studies for several damage scenarios are examined to validate results. The most efficient active cable configuration is compared with that needed for deployment. This study is divided into two phases. After the description of a 16m-span tensegrity bridge, optimally directed locations of active cables are determined in the first phase. Secondly, a procedure to ensure damage tolerance of the structure is proposed. The multi-objective self-repair procedure provides damage tolerance minimizing both maximum deflections in the structure and stresses in the structural members. Results indicate that the control strategy for deployment is a near-optimal solution for damage tolerance. The proposed methodology is applicable to a range of complex active structures.

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Structural art: Past, present and future

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Active control for mid-span connection of a deployable tensegrity footbridge

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