Jtekt Corporation

Denso Corporation

Akira Nambu

Jun Hasegawa

Terutaka Tamaizumi

Hiroshi Kawamura

Masayuki Kita

Toshihiro Takahashi

Satoru Mikamo

Akihiko Nishimura

Shinya Aono

Akihiro Tomita

Hiroshi Hosono

Takahiro Kojo

Hiroshi Suzuki

Kenichiro Aoki

Tatsuya Suzuki

Nobuyori Nakajima

Takahiro Toko

Eiji Kasai

Naoki Yamano

Hiromasa Tamaki

A steering angle calculation circuit of an ECU includes a neutral point calculation circuit, a correction amount calculation circuit, an adder, and an absolute angle calculation circuit. When started, the neutral point calculation circuit calculates a motor neutral point from a steering angle detected through a steering sensor and a motor rotation angle detected through a relative angle sensor. The correction amount calculation circuit calculates a correction angle that is a difference between a conversion value and an actual value of the motor rotation angle with respect to the steering angle. The conversion value is obtained by converting the steering angle in terms of the motor rotation angle by taking into account a theoretical specific stroke. The adder calculates a final motor neutral point by adding the correction angle calculated by the correction amount calculation circuit to the motor neutral point calculated by the neutral point calculation circuit.

Steering control unit

A steering angle calculating circuit includes a first neutral point calculating circuit, a second neutral point calculating circuit, and an absolute angle calculating circuit. The first neutral point calculating circuit calculates a motor neutral point (&#x3b8;m01), based on a steering angle detected by a steering sensor and a rotation angle of a motor detected by the relative angle sensor, when a drive source for driving a vehicle is started. The second neutral point calculating circuit calculates a motor neutral point when the steering angle detected by the steering sensor falls within a predetermined angle range in which a specific stroke with respect to the steering angle is constant. After the motor neutral point is calculated by the second neutral point calculating circuit, the absolute angle calculating circuit calculates the steering angle as an absolute angle, using the motor neutral point calculated by the second neutral point calculating circuit.

Steering control device

A steering control device has a steering actuator as an operation target, the steering actuator includes a motor and a steering mechanism mechanically connected to a rotary shaft of the motor. The steering control device includes a controller configured to perform i) a low-temperature process of changing a torque of the motor when an estimated value estimated from a temperature of a lubrication target part of the steering mechanism is equal to or lower than a predetermined value with respect to when the estimated value is higher than the predetermined value and ii) an estimation process of calculating the estimated value which is set be lower than a detected value of a temperature sensor detecting a temperature of a predetermined member attached to the steering mechanism based on a heat emission parameter of the steering actuator associated with a current flow with the detected value as an input.

In a state in which the energization in the first direction is possible between the motor and the drive circuit and the motor is not rotating at high speed, when the phase induced voltage value of the specific phase that is the target of determination is continuously equal to or smaller than the abnormality determination threshold, the abnormality detecting unit determines that an open malfunction has occurred in the relay FET of the specific phase.

Motor control device and steering device for vehicle

A motor control signal output unit of an electric power steering system includes a feedback gain calculation unit (), and a feedback control unit executes a feedback control with the use of a proportional gain (Kp) and an integral gain (Ki) that are calculated by the feedback gain calculation unit (). The feedback gain calculation unit () sets the feedback gains to large values (Kp=P, Ki=I) when the absolute value of an assist gradient (&#x3b1;) is equal to or smaller than a predetermined value (&#x3b1;) (|&#x3b1;|&#x2266;&#x3b1;). On the other hand, when the absolute value of the assist gradient (&#x3b1;) exceeds the predetermined value (&#x3b1;) (|&#x3b1;|&#x3e;&#x3b1;), the feedback gain calculation unit () sets the feedback gains to small values (Kp=p, Ki=I:P&#x3c;P, I&#x3c;I).

Electric power steering system

In a motor control unit, a current-carrying failure detection unit determines a first determination condition and a second determination condition. The current-carrying failure detection unit measures a duration of a state where the first determination condition is satisfied, and a duration of a state where the second determination condition is satisfied. When the first or second duration exceeds a predetermined reference period, the current-carrying failure detection unit determines that a current-carrying failure has occurred.

Motor control unit and vehicle steering system

A steering torque shift control amount calculation unit () calculates the steering torque shift control amount (&#x3b5;ts) by multiplying the basic shift amount (&#x3b5;ts_b) used as the basic compensation component by the transition coefficient (Kss). Then, the steering torque shift control amount (&#x3b5;ts) is subjected to the low-pass filter process in an abrupt change prevention processing unit (). An abrupt change prevention processing unit () is provided in the steering torque shift control amount calculation unit (). The transition coefficient (Kss) is subjected to the low-pass filter process in the abrupt change prevention processing unit (). The cutoff frequency of the low-pass filter that forms the abrupt change prevention processing unit () is set to a value lower than the cutoff frequency of the low-pass filter that forms the abrupt change prevention processing unit () that executes the low-pass filter process on the torque shift control amount (&#x3b5;ts).

An electric power steering (EPS) apparatusincludes a motor, an EPS actuator, a torque sensor, and an ECU. The EPS actuatoruses the motoras a drive source to apply assist force to a steering system, thereby assisting a steering operation. The torque sensordetects a steering torque &#x3c4; of the steering system. The ECUcontrols the operation of the EPS actuator. Based on the steering torque &#x3c4; detected by the torque sensor, the ECUcomputes a basic shift amount &#x3b5;ts_b of the assist force applied to the steering system. The ECUdetermines which one of returning, holding, and turning is the state of the steering operation. When the state of the steering operation is returning or holding, the ECUexecutes compensation control for correcting the steering torque &#x3c4;, which is used in the computation of the basic shift amount &#x3b5;ts_b of the assist force, thereby increasing the assist force applied to the steering system. The ECUsubjects the steering torque shift control amount &#x3b5;ts to a filtering process using a low pass filter, thereby inhibiting the steering torque shift control amount &#x3b5;ts from sharply changing. When the state of the steering operation is turning, the ECUchanges a filter constant of the low pass filter so as to reduce the filtering effect.

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Okazaki, Japan

Akira Nambu