M. Abdalla

LMI-based filter design for fault detection and isolation

A linear matrix inequality (LMI) based filter design approach for fixed-order robust fault detection and isolation (FDI) is examined. The proposed filter design provides necessary and sufficient conditions for the existence of a solution to the detection and isolation of faults using an H/sub /spl infin// formulation. These conditions are expressed in terms of LMIs with matrix rank constraints, and a parameterization of all admissible filters is provided, which corresponds to a feasible solution. A convex LMI problem is obtained for the full-order FDI filter design. Finally, the proposed methods are demonstrated using a structural system simulation example, which include faulty actuators, sensors and external disturbances.

Structural Damage Detection Using Linear Matrix Inequality Methods

In this work, linear matrix inequality (LMI) methods are proposed for computationally efficient solution of damage detection problems in structures. The structural damage detection problem that is considered consists of estimating the existence, location, and extent of stiffness reduction in structures using experimental modal data. This problem is formulated as a convex optimization problem involving LMI constraints on the unknown structural stiffness parameters. LM1 optimization problems have low computational complexity and can be solved efficiently using recently developed interior-point methods. Both a matrix update and a parameter update formulation of the damage detection is provided in terms of LMIs, The presence of noise in the experimental data is taken explicitly into account in these formulations. The proposed techniques are applied to detect damage in simulation examples and in a cantilevered beam test-bed using experimental data obtained from modal tests.

Enhanced Structural Damage Detection Using Alternating Projection Methods

Alternating projection algorithms are examined for the solution of damage detection problems in structures. The damage detection problem is formulated as a feasibility problem to find a damaged stiffness matrix that is close to the refined stiffness matrix of the undamaged structure and that satisfies the necessary symmetry, sparsity, positive definiteness, eigenequation, and damage localization constraints. Alternating projection methods are proposed to utilize the orthogonal projections onto these constraint sets in an iterative fashion to find a solution that best satisfies these constraints. In addition, directional alternating projections that exploit the geometry of the damage detection feasibility problem are introduced to improve the computational efficiency of the approach. The techniques are applied to detect damage in a simulated cantilever beam model and in the NASA eight-bay truss damage detection experimental test bed.

Linear matrix inequality based control of vehicle active suspension system

Linear matrix inequality (LMI) methods, novel techniques in solving optimisation problems, were introduced as a unified approach for vehicles active suspension system controller design. LMI methods were used to provide improved and computationally efficient controller design techniques. The active suspension problem was formulated as a standard convex optimisation problem involving LMI constraints that can be solved efficiently using recently developed interior point optimisation methods. An LMI based controller for a vehicle system was developed. The controller design process involved setting up an optimisation problem with matrix inequality constraints. These LMI constraints were derived for a vehicle suspension system. The resulting LMI controller was then tested on a quarter-car model using computer simulations. The LMI controller results were compared with an optimal PID controller design solution. The LMI controller was further tested by incorporating a nonlinear term in the vehicles suspension model; the LMIs controller degraded response was enhanced by using gain-scheduling techniques. The LMI controller with gain-scheduling gave good results in spite of the unmodelled dynamics in the suspension system, which was triggered by large deflections due to off-road driving.

Structural damage detection using strain data via linear matrix inequality based methods

Linear matrix inequality (LMI) methods are proposed for computationally efficient solution of damage detection problems in structures utilizing displacement or strain modal measurement data. The structural damage detection problem that is considered consists of estimating the existence, location, and extent of damage using simulated data. This problem is formulated as a convex optimization problem involving LMI constraints on the unknown structural stiffness parameters. LMI optimization problems have low computational complexity and can be solved very efficiently using interior-point methods. The proposed techniques are applied to detect damage in a simulation example of a cantilevered beam test-bed using displacement and strain mode shapes.

An Optimal Hybrid Expansion—Reduction Damage Detection Method

In this paper, we examine the structural damage detection problem with an incomplete set of measurements. Linear matrix inequality (LMI) optimization methods are proposed to solve this hybrid damage detection problem that integrates modal data expansion and model reduction with an LMI based damage detection procedure. In the proposed hybrid approach, the transformation matrix is based on the measured data avoiding the use of the healthy mass and stiffness matrices. The method is demonstrated using experimental modal data obtained from the NASA eight-bay cantilevered truss test bed. The experimental results of this hybrid approach are shown to provide a clearer indication of damage than using stand-alone expansion or reduction techniques.

Reduced optimal parameter update in structural systems using LMIs

The structural damage detection problem with an incomplete set of measurements is examined in the paper. Linear matrix inequality (LMI) based methods are proposed to solve the hybrid damage detection problem that integrates modal data expansion and model reduction with the LMI damage detection procedure. In the proposed hybrid approach, the transformation matrix is based on modal measurements by which we can avoid the use of healthy mass and stiffness matrices. The method is demonstrated using experimental modal data obtained from the NASA eight-bay cantilevered truss test bed. The experimental results of this hybrid approach are shown to provide cleaner indications of damage than using stand-alone expansion or reduction techniques.

Optimal Damage Detection Sensor Placement Using PSO

An optimal damage detection sensor placement methodology is presented. The techniques utilize a Particle Swarm Optimization (PSO) algorithm. The proposed method is iterative in nature and it permits the use of incomplete measurements. Also, it allows diversity of damage detection algorithms to be used to generate the PSO required fitness function. However, in this work Linear Matrix Inequalities are used as the damage detection schemes. Computer simulations of a cantilevered beam will be used to demonstrate the effectiveness of the methodology.

Head movement based control system for quadriplegia patients

A driving aid system, which utilizes only a person head movements, is designed and implemented on a small DC-Motor vehicle prototype. The system is configured to accept a pre-assigned drivers head tilts for the speed and steering control actions. The head tilts are recorded using an accelerometer, which is mounted on a head-band that fits the driver head. The head tilts collected data are transmitted via a Bluetooth transmitter after being interpreted using a Fuzzy Logic based interpreter. Once the data is received by the vehicles on-board Bluetooth module, it passes to the steering and speed servo-controllers. Both Fuzzy Logic controller and a conventional PID controller are used to carry out the transmitted commands. The driving aid system is first implemented on microcontroller Platform and is verified for proper operation using software. Furthermore, the complete integrated system is tested for functionality and performance.

Solar-Diesel Hybrid Model and Control for Central Heating

A complete technical study on a Hybrid heating system is carried out with the aid of computer simulation. The main objective of this work was to provide more insight into combining Solar and Diesel energies to be utilized in domestic central heating. The motivation for such a system was basically the ever increasing Diesel prices in the Kingdome. This work revealed that the cost of Diesel in heating houses could be lowered by at least fifteen percent if the hybrid system is implemented. Complete mathematical model of a representative house was derived for the sake of computer simulation. The model was validated and verified through computer simulations (Matlab Simulink based) with real collected weather data of Jordan (complete year record). Finally a controller strategy was devised and tested using the derived mathematical model.