Hirokazu Nishitani

Human-Computer Interaction in the New Process Technology

Abstract Systems technology has been changing its targets. This paper reviews human interaction issues in systems technology and discusses human-computer interaction in plant operation. Human-centered automation in the process industry requires the fusion of computer technology, observations in cognitive science and cooperation technology. Cooperative human-computer interaction is a solution for an intelligent manufacturing system.

HOMOGENEOUS EIGENVALUE ANALYSIS OF HOMOGENEOUS SYSTEMS

Abstract This paper focuses on the problem of stability in homogeneous systems with dilation. First, we propose an ‘homogeneous eigenvalue’ for homogeneous systems. Next, we analyze the stability of homogeneous systems using homgeneous eigenvalues, and we show that the use of positive real homogeneous eigenvalues implies instability. Finally, we show the effectiveness of the proposed method through an example.

Application of Mind State Estimation to Plant Operators

Abstract We developed a linear regression model with Electroencephalograms(EEGs) to estimate the mind state of a plant operator. First, we defined three modes according to the typical thinking state of plant operators. The classification was validated by preparatory experiments with card games, mathematical problems, and puzzles. The estimation method was applied to a plant operator who operates a boiler plant simulator under abnormal situations. As a result, the method provided the plant operators mind state, which is liable to be overlooked by analyzing with a simple interview and observation.

STABILIZATION OF HOMOGENEOUS SYSTEMS USING IMPLICIT CONTROL LYAPUNOV FUNCTIONS

Abstract This paper focuses on the problem of stabilization of homogeneous systems with dilations using implicit Lyapunov functions. In this paper, we define implicit homogeneous Lyapunov functions and implicit homogeneous control Lyapunov functions. Moreover, we proposed a design method of implicit homogeneous control Lyapunov functions and a controller design method based on the functions. Finally, we confirmed the effectiveness of the proposed method by computer simulation.

Robust control of an absorption heat pump system

An absorption heat pump system is a complex nonlinear system. We proposed a practical procedure of controller design based on the idea of global linearization. Numerical simulation runs have illustrated this procedure is practical and effective for the complex nonlinear system.

STABILIZATION OF NONHOLONOMIC SYSTEMS USING HOMOGENEOUS FINITE-TIME CONTROL TECHNIQUE

Abstract This research focuses on the problem of finite-time stabilization of chained-form nonholonomic systems using discontinuous homogeneous feedback and introduces the discontinuous homogeneous (with dilation) controller. The proposed controller has no singular point, stabilizes the system in finite-time, and is not complicated. Moreover, we demonstrate an exponentially stable controller.

Operation Support System Using Dynamic Simulation for a Combined Batch/Continuous Plant

Abstract Operation of a combined batch/continuous plant generates difficult problems because both discrete and continuous dynamics must be considered in plant operation decision making. In resolving these problems, a dynamic simulator which predicts plant-wide states is useful. This paper illustrates an operation support system with operational guidance derived from the model predictive control concept This system was implemented in an actual plant, yielding considerable productivity increase and continuous unit stability

Plant Operator Model for Human Interface Evaluation

Abstract A simulation environment of plant operation, which consists of an operator model, a human-machine interface (HMI) model and a plant model was developd. When the operator model recognizes an abnormal situation, the model generates a countermeasure program in its short-term memory based on both the plant state information acquired from the plant model through the HMI model and the knowledge bases installed into the operator model. A comparison between the operator models behavior and the human operators behavior under the same malfunction was used to extract the characteristics of the human operator and to obtain information on human errors.

Failure Detection by Auto-Associative Neural Networks

Abstract One method to judge whether plant operation is normal or not is to check whether measurement variables maintain the specified functional relation extracted at normal operation. However, it is difficult to identify the relation among measurement variables in a nonlinear process. In this paper, we apply the five layered auto-associative neural network to extract the functional relation from operating data. Then, a method to design the neural network with minimum parameters is proposed. Relation of measurement variables in the continuous polymerization process with PI control loops is identified as a normal operation model, and failure detection based on the model is examined.

Sequential Control Issues in the Plant-Wide Control System

Abstract We have applied the model checker using the computation tree logic (CTL) to automatic verification of the sequential control system, of which mechanism is defined by the rules in series. The rule transition graph and the modified CTL formulas were introduced to determine if the system satisfies the specifications.