This paper presents a method of PI control parameter tuning based on the estimated maximum step disturbance and the allowable peak value of the controlled variable and shows its effectiveness and limitation by simulation studies. This method is very useful to tune control parameters for chemical processes where limitations on loss prevention and quality control are represented by peak values of controlled variables.
In recent years, due to the fall of market price of plant control systems, improvement of the system engineering environment is required to increase productivity of the systems including control programs. In this situation, making reusable blocks of control programs, as represented by the function blocks of the international standard IEC61131-3, is attempted. However, the function block lacks the concept of abstraction of object-oriented programming. Therefore in the real situation, it is hard to construct reusable blocks. Furthermore, in the engineering of plant control systems, not only control programs but also process I/Os, equipment informations and specification documents have to be managed integratedly. In this paper, we present a new engineering model based on the object-oriented framework. The concepts of encapsulation and abstraction are introduced to the data-flow based graphical programming such as the IEC61131-3 function block diagram. A prototype engineering tool based on the model is also described.
A method to design digital preview sliding mode servo system is proposed. Sliding mode regulator theory is applied to an augmented error system in which obtainable desired signals or disturbance signals are added. The equivalent control which make the states of error system stay on the switching surface is employed. Then, the sliding mode controller is designed. Preview sliding mode servo system by using this control has both merits of the preview control and the sliding mode control. The computer experiments are given to illustrate the effectiveness of the proposed deign method.
An automatic font selection and a character arrangement technique based on human Kansei, a Japanese word that means a comprehensive mental activity, are proposed to aid non-designer people who design a signboard, headline, etc. The design technique by using human Kansei has an advantage, which decreases the risk that the design image deviates from a popular one. In this paper, a signboard design for a shop is considered as an example, and the experiments are carried out on the following two items : First, how to select a font well matched to the type of the shop, and secondly how to arrange the characters so that the intervals between them are well balanced within the given area. It is shown that a proper introduction of an additivity of human Kansei into the font selection is effective, and the character arrangement by means of a potential field based on the theory of induction field on retina is useful.
The coordinated traffic signal control parameters are characterized by cycle length, split and offset. These parameters should be carefully calibrated so that the total performance index is optimized. Our scope of opitimization is called sun-area, which is defined by a series of intersections. The conventional methods may be deficient in that each parameter is calculated individually and the overall traffic index is not considered. This paper describes a new method of determining coordinated control parameters simultaneously. Since it is difficult to express the delay time as a function of the offset parameter, the procedure is divided into two parts. In the first step, the cycle length and the split are obtained by minimizing the total traffic delay. The optimal offset is calculated so as to maximize the bandwidth, which is the fraction of time during which vehicles may pass through all the intersections without stopping in the sub-area. In the second step, we estimate the total queue length in the sub-area by using a microscopic traffic flow simulator. By integrating these two steps, several control planes are obtained, and the best solution is chosen among them.
This paper describes the facility location problem of mobile relay stations which connect the head office and sensing vehicles for the fast and accurate communication in the case of disaster or urgent situation. The optimal decision of locating relay stations and assigning the radio frequencies for the robust and accurate communication are discussed. The major feature of this paper is that the robustness for multiple communication paths and the high accuracy of communication should be held even if any one of the relay stations becomes out of use. This problem can be formulated as the min-max decision problem of minimizing the decrease of the communication power, which is the combined concept of the number of redundant paths and the communication accuracy, when the most critical station is damaged. This paper proposes a solution method for this nonlinear integer programming problem using the simulated annealing with matrix calculation. The efficiency of the proposed method is shown for concrete numerical examples.