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Optimal placement of actuators and sensors in thin-walled composite I-beam: an observability-controllability-based approach

Mohanty, Subhasish and Bhat, Seetharama M (2003) Optimal placement of actuators and sensors in thin-walled composite I-beam: an observability-controllability-based approach. In: SPIE: Smart Materials, Structures, and Systems, 12-14 December, Bangalore, India, Vol.5062, 661-668.

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Abstract

The optimal utilization of smart sensors and actuators in complex aerospace structure largely depends on the position of the actuators and sensors. Since piezo-ceramic material for active component have inferior specific strength compared to host structure, it is desirable to use patches of active materials instead of distributed actuation throughout the structure. In the present paper, the cost function for selecting the best actuator and sensor positions are found from the orthogonal projection of structural modes into the intersection subspace of the controllable and observable subspaces corresponding to any actuator and sensor locations. The cost function depends on the observability and controllability grammians. The observability and controllability grammians are found for the reduced order state space model (total number of states = 2n = 6). The '2n' state space model is found after reduction of full-order finite element model (total number of nodal DOFs = N = 140) through modal truncation. The optimal positions of actuator and sensor are found in two stages. First few actuator and sensor positions (8 actuator and 8 sensor positions) are selected from modal projection of three lowest transverse modes, with one actuator and one sensor at a time. After selection of the set of possible actuator and sensor positions the process of modal projection is repeated with two actuators and two sensors at a time. The first stage selection leads to $^8C_2 X ^8C_2$ possible positions from which the best two actuator and two sensor positions are found in the next stage search process. The two stage search process helps in substantial reduction of computational time in a repetitive search in a large pool of admissible actuator-sensor locations. To ilustrate the optimal placement method, numerical simulation is performed for thin-walled composite I-beam.

Item Type: Conference Paper
Additional Information: Copyright of this article belongs to The International Society for Optical Engineering.
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering (Formerly, Aeronautical Engineering)
Date Deposited: 27 Apr 2007
Last Modified: 27 Aug 2008 12:42
URI: http://eprints.iisc.ernet.in/id/eprint/10207

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