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Mitsubishi Electric has developed a concept car “EMIRAI 2 xEV” that features an electric vehicle (EV) powertrain for safe, comfortable, eco-friendly driving experiences in the future. The vehicle was exhibited during the 2013 Tokyo Motor Show and the 2014 Automotive Engineering Exposition. The xEV is a four-wheel-drive EV with three motors: a water-cooled front motor and two air-cooled rear motors with integrated inverters. The rear wheels can be driven independently. The degrees of freedom of the actuation can realize improved maneuverability and safety. The vehicle is also equipped with an onboard charger with a built-in step down DC/DC converter, an EV control unit, a battery management unit, and electric power steering. All of the instruments are developed by Mitsubishi Electric. Motion control systems for the xEV have been developed based on our proprietary motor control technology.

This article discusses a vehicle stability improvement control method that utilizes an electric power steering system (EPS) with blushless motor. The purpose is to improve the vehicle stability by increasing the steering return torque in a region where the alignment torque is saturated due to the driver's excessive steering maneuver on a slippery road. In this study, a factor analysis was performed for the alignment torque on a slippery road and the basic control to improve the vehicle dynamics stability is studied by using a linear m1odel. Next, a new control algorithm was developed based on these studies. Finally, the new control algorithm was verified to be effective through an on-vehicle test. The proposed strategy can be realized only by adding a steering wheel angle sensor signal to a conventional EPS. That can be easily obtained from electronic stability control system.

Accuracy of positioning with GNSS (Global Navigation Satellite System) has been improved in recent years. Especially in Japan, high accuracy GNSS service, QZSS (Quasi Zenith Satellite System), will start in 2018 and the first QZS, “MICHIBIKI” has been already launched. They will broadcast correction data which enhances GNSS performance and realize cm-order positioning. In this paper, we, Mitsubishi Electric develop the estimation algorithm of vehicle position and attitude and also adapt the algorithm to a test vehicle which can trace automatically the calculated path with EPS (Electric Power Steering) and high accuracy GNSS. Although the GNSS receiver calculates the longitude and latitude of the vehicle every second, it is not enough to control vehicle dynamics smoothly. So we estimate vehicle position and attitude of the vehicle with GNSS and vehicle sensors in high frequency.