Nsk Corporation

Kei Chin

Shuji Endo

Hideyuki Kobayashi

Hideaki Kawada

Yusuke Itakura

To provide a controller of an electric power-steering system, capable of improving the steering performance by presuming a motor angular speed .omega. in a range in which the angular speed of a motor is small and moreover very accurately presuming the motor angular speed and thereby, completely showing the functions for compensating the inertia of the motor and controlling the astringency of a vehicle. Because the presumed error of a back electromotive force between a model motor and a motor to be actually mounted is proportional to a motor current, a dead zone of a motor angular speed having a width proportional to a motor current is set to the presumed value of the motor angular speed. When the motor current is small, the width of the dead zone also decreases. Therefore, it is possible to presume an angular speed .omega. even in a region where the motor angular speed is small. Moreover, a motor angular speed is presumed by defining impedance models of motor driving systems in an intermittent mode and a continuous mode.

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Maebashi, Japan

Kei Chin