Current Amplifying image sensor with buried driving electrode has been proposed to increase photosensitivity and dynamic range. The characteristics of the image sensor with 1, 000×1, 000 cells/cm² were simulated at the readout-current saturation region. The simulation are carried out by one dimensional depletion approximation and three dimensional numerical analysis. The simulations clarified that the current amplifiing factor at the saturation region and the charge handling capability reaches 42 and 1.35×10⁵holes/cell, respectively. The simulations also clarified that the ratio of signal current to stored signal charge increases in propotion to the inverse of a cell size.

抄録全体を表示

Using the observer-based integral controller proposed by Ishihara, et al. as a basic controller, we propose a state-space parametrization of discrete-time two-degree-of-freedom integral controllers accounting general computation delays. The proposed parametrization can easily be obtained by using the solution of an LQG problem for a plant and does not require constraints on the two free parameters. The role of the free parameters are clarified in connection with the basic controller. As applications of the proposed parametrization, we discuss the loop transfer recovery and the pole assignment using the free parameters. A numerical example is presented to show the effectiveness of the proposed methods.

抄録全体を表示

The purpose of this paper is to develop a fuzzy reasoning control law for an inverted pendulum system by the aid of the theory of variable structure systems (VSS). The cascade architecture of two fuzzy controllers is used for considering of interation with the cart. The stability of the control systems is investigated by the reachability and the existence conditions for the sliding mode. The simulation and experimental results are given to demonstrate the validity of our design method.

抄録全体を表示

This paper presents a modified taught data method for accurate contour control of mechatronic servo systems by using a Gaussian network. The Gaussian network reflects an inverse dynamics of the second order model for the mechatronic servo system. The input data for the contour control of the servo system are modified from objective trajectories by using the Gaussian network to attain the accurate contour control. Effectiveness of the proposed method was assured by experimental results of an X-Y table.

抄録全体を表示

It is important to remove the transitional peak current in sense-emitter current which occurs by dynamic currents sharing during turn-on for a design of IGBTs with current sense used protection against overcurrent and short circuit. But this analysis has been scarcely investigated.
This paper makes clear generation mechanisms of the transitional peak current by simulations and experiments using a parallel operation model and reports on techniques to remove it.
The following results were obtained.
(1) In the two paralleling devices model which consists of a sense cell and main cells, the transitional peak current occurs during turn-on when a sense cell turns on faster than main cells do. In this case, main parameters that effect dynamic currents imbalance are gate resistance (Rg) and gate threshold voltage (Vth).
(2) In dynamic currents imbalance based on individual Rg and Vth among main cells, it may treat as a two paralleling devices model consists of a sense cell with Rgs and Vths, and main cells with average values Rgm and Vthm.
(3) The transitional peak current can be removed by the design that Rgs and Vths in a sense cell are larger than average values Rgm and Vthm in main cells.
(4) We manufactured on trial IGBTs with current sense that Vths in a sense cell is different from average value Vthm in main cells to change impurity concentrations of each channels. And we confirmed that the transitional peak current in senseemitter current can be removed by the design that Vths in a sense cell is larger than average value Vthm in main cells.

抄録全体を表示

This paper presents a fuzzy diagnosis support system for fatty liver and an algorithm of membership function acquisition in consequent clause in this system. This system shows the possibility of fatty liver using fuzzy inference from blood tests. In constructing this fuzzy system, the expert knowledge must be represented by fuzzy if-then rules. However, the membership function acquisition in the fuzzy if-then rule is time consuming owing to less information about the weight of each clinical fatty liver diagnostic rule. This algorithm calculates the relative positions and widths of membership functions in consequent clause using the probabilities of fuzzy events and the specificities of fuzzy sets in antecedent clause. Furthermore, the membership functions are detected by optimization using learning data. The input of this system is the values of five blood tests: ChE, GOT, GPT, ALP and LAP. The output is the possibility of fatty liver. To evaluate the performance of our system, we have applied it on 59 cases. Our system correctly diagnosed 30 cases as fatty liver, because the possibility of fatty liver was one. These 30 cases were diagnosed as fatty liver by both the ultrasonic imaging and blood test methods. For the remaining 29 cases our system showed the possibility of existence of fatty liver, where ultrasonic imaging diagnosed them as fatty liver, but the blood test method evaluated them as normal. We would expect the usefulness of this system to be evident in fatty liver diagnosis using the blood test data.

抄録全体を表示

Parameters of a DC servomotor, such as torque coefficient Kt, induced voltage coefficient Ke, armature resistance R, and damping coefficient D are identified at several operating points of the motor using the extended Kalman filter as a parameter estimator. A known M series random signal is used as a test signal to fluctuate input voltage of the motor so that the performance of the parameter estimation can be much improved. It is seen from the results of the estimation that a test signal suitable for this estimation is dependent on the kinds of parameters to be identified; a M series signal with shorter maximum pulse width is suitable for estimating R and Kt, while a signal with longer is suitable for D, and any signal is all right for Ke. The results are proven by investigating the observability of each paramater estimation system. It is also seen from the results of this identification that Kt or Ke is identified close to its nominal value offered from the manufacturer, while R or D is identified somewhat far from its nominal value. R shows a slight decrease with an increase in motor current. This suggests that the effect of brush contact resistance is not negligible. It is also suggested that it is difficult to estimate in advance D in actual operating conditions.

抄録全体を表示

A double-cell type zirconia oxygen sensor which consists of two solid electrolyte cells, a pumping cell and a sensing cell, has a capability to measure an air-to-fuel ratio widely extended from rich to lean. When the sensors operated in air, solid electrolyte of some of the sensors deteriorated. The sensors which can not operate in air have few applications, because air is the only reference gas with constant oxygen concentration easily obtained everywhere.
To clarify the cause of the deterioration, polarographic characteristics of the oxygen sensors are studied carefully in air. The study shows the difference between deteriorated sensors and durable sensors. Electromotive force of sensing cells increase more slowly for deteriorated sensors when pumping current are increased gradually. The slow increase implies that oxygen partial pressure are extremely low locally at the cathode of the pumping cell.
To protect the sensors from the deterioration, methods to increase oxygen partial pressure at cathode are studied. Auxiliary pumping from the sensing electrode is found to be effective, and the optimum auxiliary pumping method is to leak pumping current from the pumping cell. Oxygen sensors with auxiliary pumping were not deteriorated in a continuous operating test in air.

抄録全体を表示

It is well known that a guard shielded isolation amplifier has a large common mode rejection ratio (CMRR). And it is used in an instrumentation system having many analog inputs. However, the overall CMRR characteristics of an anolog input system that is composed of a signal source, a wiring, a multiplexer and an isolation amplifier was not studied theoretically.
In this paper, we propose the simple equivalent circuit of the circuits composed of the signal source, the wiring, the multiplexer and the input part of the isolation amplifier, its transfer function (IG(s)) and the overall CMRR characteristics as the product of the IG(s) and the AG(s) which is the I/O transfer function of the guard shielded isolation amplifier. And, we introduce the delay time factor (e^-S7) in order to express correctly the I/O characteristics of the guard shielded isolation amplifier into the AG (s). To confirm that the theoretical overall CMRR characteristics represent properly the CMRR characteristics of the actual analog input system, we carry out the experiments on the frequency characteristics and the transient response.

抄録全体を表示

In order to specify and verify real-time systems, formal languages for reasoning about quantitative timing properties are necessary. We have developed a model checking algorithm for the verification of real-time systems, where the given real-time system is modelled by a time Petri net, and properties to be verified are expressed by a real-time logic.
In this paper, we verify a railway crossing controller as a case study of verification with this method. The railway crossing controller as well as trains, a crossing gate and so on are modelled by time Petri nets. Two properties: (1) that the crossing gate completely shuts down 15 seconds before train reaches to the crossing, and (2) that the crossing gate never rises as long as the train is in the warning zone, are expressed by a real-time logic. The verifier has found a bug in the control program given first, and shown that the two properties hold henceforth in the modified control program.

抄録全体を表示