The problem of output dead-beat control with asymptotic disturbance rejection for linear discrete-time systems with disturbance input is considered. The system considered is composed of the plant to be controlled and the disturbance generator whose state vector is the disturbance input to the plant. We propose a design method of the controller which is organized by the feedback gain to stabilize the closed-loop of the plant and the compensator for the disturbance. It is shown that the proposed controller can force the output of the plant to zero and keep it zero by using the measurement output of the augmented system and the estimate of the disturbance which is obtained from the adaptive estimation process composed of an unbiased linear functional observer and an adaptive state observer. Some numerical examples show the validity of the proposed controller.
In this paper, we propose a method for obtaining accurate derivatives of observed signals on real time; we propose the Numerical Differential Formula via Linear Combinations of Sampled Data, based on a necessary and sufficient condition under which the linear combination of sampled data is the numerical differential formula. We investigate its property of differentiating general observation signal which includes random noises and give methods for minimizing the variance of error and for assigning the phase. A design approach using empirical rules simplifies selection of parameters by trial and error.
This paper deals with an operation assignment problem. The problem is to process N products at one of parallel H machines in order to minimize the deviation of the processing time of each product from its desirable time interval. Then, we have to determine both the order and the machine to process each product. The genetic algorithm (GA) is applied to this problem. Several individual descriptions and the related decoding methods are proposed. By examining numerical results, comparison is made among these individual descriptions from the viewpoints of accuracy and computation time. Consequently, the best individual description is found to be the one defined in such a way that both the order and the machine are determined by GA.
We consider a multi-project scheduling problem with time constraints on resources, which appear in the planning of new projects that need to use the same resources as other projects under execution. We seek the optimal sequence of activities and the shortest completion time for all projects taken together. We propose a solution procedure using a branch and bound method for small size problems, where the bounding operations are established by a lower bound as well as an equivalence relation between the sequences of activities. An approximate solution by heuristics is required because of the high computational complexity. The approximate solutions obtained by eight heuristic rules are compared with the shortest completion times by using randomly generated simulating problems. We conclude that an earliest finishing time order rule provides effective heuristic rules for multi-project planning with time constraints on resources; however, a latest finishing time order rule is effective for a large-scale project.
In a file system, checkpointing is inevitably necessary to recover the system once the system failure occurs. If the checkpointing is frequently carried out, the cost for generating checkpoints increases. On the other hand, if the number of checkpointing is small, the recovery cost via the journal increases when the system failure occurs. Thus, it is important to determine theoretically the optimal checkpoint sequence which minimizes the expected cost. In this paper we consider the situation in which all data files in a secondary storage can be destroyed by the media failure occurring at the checkpoint, and derive the optimal checkpointing policy. The fault tolerant design by taking such a catastrophic media failure into account is of great use to achieve the high reliability from the standpoint of risk avoidance.