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A small. low-cost piezoresistive acceleration sensor suitable for automotive applications such as advanced breaking control and suspension control systems has been developed. A piezoresistive semiconductor sensor has such advantages as high output linearity, long-term output repeatability and DC response a piezoelectric sensor doesn't feature. One drawback. however, is that piezoresistive characteristics are quite temperature sensitive: Such that temperature dependence of DC offset and span have to be compensated with a certain electrical circuit. With 1 mV/Vs/G, the low sensitivity of the acceleration sensor [Vs:bridge voltage. G:gravitational acceleration], the temperature shift of DC offset represented in terms of the sensitivity, becomes relatively high.

An SOI type pressure sensor has been developed which can measure pressure at high temperature environments above 150°C. SOI stands for Silicon On Insulator. A single-crystalline silicon layer is located on an insulating layer formed on a silicon substrate. The piezoresistors of the SOI type pressure sensor are made from the single-crystalline silicon layer which is isolated from the silicon substrate by the insulating layer. There is no leakage current from the piezoresistors. The SOI structure is made by the laser-recrystallization-method. The properties of the SOI type pressure senor are as good as conventional semiconductor pressure sensors.

This paper is concerned with a scan laser radar sensor used to measure distance. It s a basic component of a vehicle distance warning system or an intelligent cruise control system. An intelligent cruise control system requires not only the distance to the object, but also the ability to detect movement of the preceding vehicle and the existence of any other nearby obstacle. However conventional radar sensor mainly fixed beam technology and measure only distance. Therefore, it s insufficient for the application to an intelligent cruise control system. Our newly developed scan laser radar transmits an extreme narrow beam and scans both transmission direction and reception direction simultaneously at a high measurement time rate. This scan laser radar can measure the lateral position of objects with high accuracy and good reconstruction level.

This paper proposes a new Electric Power Steering (EPS) control strategy that enables improvement to steering-wheel returnability. Using a conventional EPS controller, frictional loss torque in the steering mechanism reduces steering-wheel returnability, which drivers occasionally perceive as unpleasant. This phenomena occurs in any EPS system regardless of motor type or mounting location. To improve steering-wheel returnability for EPS-equipped vehicles, we developed a new control strategy based on estimation of alignment torque generated by tires and road surfaces. This proposed control strategy requires no supplemental sensors like steering-wheel angle or motor-angle sensors. We experimented with this proposed control algorithm using a test vehicle and confirmed that it enables improved steering wheel returnability and also better on-center feeling.

This paper proposes a new Electric Power Steering (EPS) control strategy that enables remarkable progress on steering maneuverability for stationary vehicles. Using a conventional controller, undesirable steering vibration prevented us from reducing steering torque. To eliminate this vibration, we developed a new control strategy based on damping for specified frequency using a motor angular-velocity estimator. We experimented with this proposed control algorithm using a test vehicle and confirmed that it enables reduced steering torque without any perceived vibration for drivers. Concerning the gradient of the assist-map, the proposed control strategy enabled more than three times higher compared with that of the same type vehicles on the market as the test vehicle. This proposed control strategy requires only the torque sensor signal, supply voltage and current to the motor, which are used in the conventional EPS systems, so no supplemental sensors are required.

We have developed a new series of revolution sensors using Giant Magnetoresistive (GMR) elements. We call these GMR revolution sensors. In automotive applications, revolution sensors have traditionally utilized Hall effect and anisotropic magnetoresistive (AMR) elements. Recently, more sensitive revolution sensors are necessary for improved control of engines, braking systems and automatic transmissions. Since GMR elements have one order higher MR ratio than AMR elements, GMR revolution sensors are much more sensitive. Furthermore, GMR elements have been integrated with circuits on Si substrates. This integration simplify the assembly process and increases the reliability of the GMR revolution sensors. This paper discusses the superiority of GMR sensing elements over Hall and AMR elements. This paper also reports the characteristic results of the GMR sensor.