A Markovian Control Approach to Maintenance Optimization of a System with Stochastic Dependence and Hidden Failures

Given partial information, this paper considers both disruption and maintenance scheduling problem for a parallel-series system with failure interactions and hidden failures. By projection on an observed history, the filtering treatment contributes to detecting an unobservable disruption time at which one of subsystems experiences failure. The model is developed by setting it in a Markovian control framework with partial information pattern in which a control process as a repair level impacts on the system availability via maintaining both the inspection and the disruption intensity at a desirable level. Since each repair and maintenance action incurs cost, the problem is to determine an optimal control process that balances the amount of maintenance and maintenance costs. The optimal control process emerges as the solution of deterministic Hamilton Jacobi equations, and a recursive scheme is used to solve them. We illustrate the procedure for the case when the failure time of components is defined as the first passage time of a Wiener process. The proposed model is illustrated through numerical examples.

Analysis of helicopter vibratory hub loads alleviation by cyclic trailing-edge blade flap actuation

The aim of the present work is the investigation about the use of blade trailing-edge flaps for the reduction of vibratory loads arising at the hub of helicopter main rotors in forward flight. The alleviation of these loads is achieved through multicyclic higher harmonic actuation of the blade flaps, which is related to measured vibratory loads amplitude. The feedback control law is obtained by an optimal control process based on the minimisation of a cost function, under the constraint of compatibility with the nonlinear equations governing blade aeroelasticity. In the numerical investigation concerning a four-bladed rotor in level flight conditions, a computationally efficient local controller methodology is applied, with the attention focused on the effectiveness of the control algorithm, along with its robustness with respect to differences (existing in real applications) between the aeroelastic models used for control law synthesis and validation.

ON FUZZY OPTIMAL CONTROLS IN THE WEAKLY STRUCTURABLE CONTINUOUS DYNAMIC SYSTEMS (WSCDS)

We pose problems of the WSCDS optimal control and discuss the results developed by G. Sirbiladze in Ref. 7. Sufficient and necessary conditions are presented for the existence of an extremal fuzzy optimal control process, for which we use R. Bellman's optimality principle and take into consideration the gain-loss fuzzy process. An example of constructing the continuous extremal fuzzy dynamic systems optimal control is presented.