A Near-Optimal Decentralized Servomechanism Controller for Hierarchical Interconnected Systems

This paper is concerned with decentralized output regulation of hierarchical systems subject to input and output disturbances. It is assumed that the disturbance can be represented as the output of an autonomous LTI system with unknown initial state. The primary objective is to design a decentralized controller with the property that not only does it reject the degrading effect of the disturbance on the output (for a satisfactory steady-state performance), it also results in a small LQ cost function (implying a good transient behavior). To this end, the underlying problem is treated in two phases. In the first step, a number of modified systems are defined in terms of the original system. The problem of designing a LQ centralized controller which stabilizes all the modified systems and rejects the disturbance in the original system is considered, and it is shown that this centralized controller can be efficiently found by solving a LMI problem. In the second step, a method recently presented in the literature is exploited to decentralize the designed centralized controller. It is proved that the obtained controller satisfies the pre-determined design specifications including disturbance rejection. Simulation results elucidate the efficacy of the proposed control law

Research on optimal control, stabilization and computational algorithms for aerospace applications

The research carried out in the areas of optimal control and estimation theory and its applications under this grant is reviewed. A listing of the 257 publications that document the research results is presented

Optimal control of an internal combustion engine and transmission system

The control of an internal-combustion engine such that it will produce its required output, with a minimum consumption of fuel, even in the presence of random load disturbances, has become a necessary requirement for future prime-mover and vehicular applications. This thesis is concerned with an attempt to produce a practical scheme to meet that requirement from a study of several methods of achieving optimal engine regulation and a method of obtaining optimal start-up. An attempt was made first to identify the response of the engine-transmission-load combination with a mathematical model obtained by the use of computers. The servo-mechanism associated with the throttle was identified also, and then a complete state-variable description of the system was obtained. Next an automatic gear-changing scheme was designed and implemented. With the availability of this practical system an optimal control function was generated then to implement optimal start-up. The optimal function was calculated by solving the associated multi-point boundary value problem by means of technique of quasi-linearisation. To subject the system to random loads an artificial road was simulated, and a scheme was devised to vary the dynamometer loading in response to this 'road' signal. The remainder of the thesis is concerned with a study of several different methods of obtaining optimal or sub-optimal schemes of regulation and with comparisons of experimental results and the results from associated theoretical computer studies. Many suggestions for further investigations are contained in the final chapter