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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.

Recently, development of vehicle control system targeting Full Driving Automation (autonomous driving level 5) has advanced. Some applications of autonomous driving systems like the Lane Keeping Assist system (LKA) and Auto Lane Change system (ALC) (autonomous driving level 1-3) have been put on the market. However, the conventional system using information from front camera, it is difficult to operate in some situations. For example the road that no line, large curvature and number of lane increases or decreases. We propose an autonomous driving system using high accuracy vehicle position estimation technology and a high definition map. An LKA system calculates the target steering wheel angle based on both vehicle position information from the Global Navigation Satellite System (GNSS) and the target lane of high the definition map, according to the method of front gaze driver model. Then, the system controls steering the wheel angle by Electric Power Steering (EPS).

A robust cruise control system using a disturbance observer is proposed. A control design method based on the two-degree-of-freedom (2-DOF) control including a disturbance observer is introduced. The proposed controller provides that: (1) input command responses are not affected by driving condition, such as vehicle speed, and road gradient (2) input command response and disturbance suppression performance can be designed independently (3) choice of an appropriate parameter value in the disturbance observer depending on the throttle opening gives a proper trade-off between the robust performance and the robust stability over a wide driving range. Simulation and experimental results show that the proposed system is robust against both parameter variations and disturbances.

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 vehicle state detection method for improving the stability of vehicles equipped with electric power steering (EPS) and electronic stability control (ESC) systems. ESC is an effective vehicle stability control system that operates within a vehicle's stability limitations. Generally ESC uses a vehicle state signal such as yaw rate. To enhance the ESC function so that it can alleviate understeer, a process that is capable of detecting understeer is required. This concept motivated us to develop a vehicle state detection algorithm based on estimated self-aligning torque using EPS. It is well known that maximum self-aligning torque occurs before maximum cornering force is reached. We have confirmed that the proposed algorithm can detect understeer earlier than conventional means based on vehicle yaw rate.

A piezoresistive semiconductor pressure sensor that can be measure high pressure upto 3.5 Mpa within ±1% error of FS (Full Scale) has been developed; it is suitable for use in automotive electronic control systems such as suspension, transmission, anti-skid brakes and air conditioners. This pressure sensor has a silicon diaphragm in which piezoresistive elements are diffused and form a wheatstone bridge circuit to newly developed to achieve high accuracy. High resisting pressure of more than 10 MPa (300% of rated pressure) and high sensitivity of more than 100mV/V supply ·3.5 MPa were achieved by the optimum designe of diaphragm shape.

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.

In JAPAN some ICCs (Intelligent Cruise Control systems) with recognition systems using Laser Radar have been produced since 1995. However these recognition systems have some improvement challenges; 1) Improvement of detectability for less reflective objects, 2) Improvement of identification performance of a vehicle to be tracked in the same lane (a target vehicle), 3) Improvement of detection performance under bad weather condition. We are developing a New Recognition System using sensitive Laser Radar with APD (Avalanche Photo Diode) as a solution for these challenges. In this paper, we will describe our experimental system using sensitive Laser Radar, especially, algorithm for target vehicle recognition and its performance.

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.

Mitsubishi Electric has been developing a lane keeping assist system (LKAS). This system consists of our products such as an electric power steering (EPS), a camera, and an electronic control unit (ECU) for ADAS. In this system, the camera detects a lane marker, the ECU estimates reference path and vehicle position, and calculates reference steering wheel angle, and the EPS controls a steering wheel angle based on reference steering wheel angle. In this paper, we explain the calculation method of reference steering wheel angle for path tracking control. We derive a formula of reference steering wheel angle calculation that converges lateral position deviation in desired time by using lateral position deviation change rate control on forward gaze point as path tracking control algorithm. Since the formula is obtained from the vehicle model, we can easily design a controller depending on the vehicle type, by using known vehicle specifications.