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Sensors which can detect minimal acceleration such as ± 9.8 m/sec2 in longitudinal and lateral direction of a vehicle, for DC to 20 Hz range, are required to control ABS (anti-lock braking system) or suspension system. To fulfill these requirements, we have developed a one-dimensional acceleration sensor, using magnetic fluid, to control the vehicle. In 1992, we submitted a paper on this sensor at the SAE International Congress and Exposition. Based on this one-dimensional acceleration sensor, we have developed an acceleration sensor which can detect two dimensional acceleration using a single inertia mass. This sensor is compact and can detect minimal acceleration with high accuracy. Spring and damping functions were obtained via the adoption of magnetic fluid, as in the case of the former one-dimensional acceleration sensor. This sensor can sustain mechanical shocks.

In vehicle control systems such as ABS (anti-lock braking system) or active suspension control, sensors for detecting longitudinal and/or lateral acceleration of vehicles (acceleration of up to ± 9.8 m/s2, with frequency range of DC to 20 Hz) is necessary. The principle of acceleration detection for this sensor is as follows. A permanent magnet levitates steadily in magnetic fluid by the action of the magnetic field generated by the magnet itself. The magnet moves by the application of acceleration on the mass of the magnet. This change of position of the magnet is detected by the Hall element, and thus acceleration is measured as an electrical signal. This sensor consists of only magnetic fluid, a permanent magnet, housing, a pair of Hall elements and an electronic circuit.

A Slow Active Suspension system has the advantage of requiring less energy than a Full Active Suspension system. But for improving vehicle's attitude control, feed-forward control becomes of paramount importance. This paper describes the control algorithms utilized in the Slow Active Suspension system that Toyota has just made available on the Japanese market. Special control items specifically developed for this system are; I ) The parameter Kwt, which is the ratio between the estimated differential value of lateral acceleration from steering angle velocity and that from lateral acceleration sensor in order to realize fast response to transient roll control, II ) Side Slip Judgement, which prevents the feed-forward errors in the case of changing co-efficients of surface friction, III ) Heave control, which prevents the vertical motions caused by heave disturbance force in the suspension cylinders during high-G turns.

A system to measure transient temperature distribution on the brake disc rotor at high speed braking has been developed and its measuring principle and configuration were discussed in this paper. This system consists of two revolution sensors and two sets of optical fiber array, photoelectric elements, and microprocessor, which fiber array is so arranged that it faces the brake disc rotor. This new system has the following features: (1) Measuring is made using a visible radiation wavelength range for red hot temperatures higher than 550°C.