Abstract: There is provided an electric power steering system that makes it possible to improve the driver's steering feel, and that includes a controller that controls driving of a motor. The controller computes a first assist component based on a steering torque. The controller computes a torque command value based on a basic drive torque that is the sum of the steering torque and the first assist component, and computes an assist compensation component through feedback control based on the torque command value. The controller computes a steered angle command value based on a value obtained by adding the assist compensation component to the basic drive torque, and computes a second assist component through feedback control based on the steered angle command value. The controller controls driving of the motor based on an assist command value that is the sum of the first assist component and the second assist component.

Abstract: A motor is driven by the ?-axis current of a ?? coordinate system that is an imaginary rotating coordinate system. A command current value preparation unit sets the ?-axis command current value based on the command steering torque and the detected steering torque. The command current value preparation unit includes a command current increase/decrease amount calculation unit and an addition unit. The command current increase/decrease amount calculation unit calculates the current increase/decrease amount for the command current value based on the sign of the command steering torque and the deviation of the detected steering torque from the command steering torque. The current increase/decrease amount calculated by the command current increase/decrease amount calculation unit is added to the immediately preceding value of the command current value by the addition unit. Thus, the command current value in the present calculation cycle is calculated.

Abstract: A current increase-decrease amount (?I?*) computed by a command current increase-decrease amount computing unit is added to an immediately preceding value (I?*(n?1)) of a command current value (I?*) in an adder. The command current value (I?*) obtained by the adder is given to a high/low limit limiter. The high/low limit limiter limits the command current value (I?*), obtained by the adder, to a value between a low limit value (?min (?min?0)) and a high limit value (?max (?max>?min)). A high limit value setting unit obtains the high limit value (?max) corresponding to the vehicle speed detected by the vehicle speed sensor, from a vehicle speed-vs.-high limit value map set by a map creating/updating unit, and sets the obtained high limit value (?max) in the high/low limit limiter.

Abstract: A motor control unit controls a motor including a rotor and a stator facing the rotor. A current drive unit drives the motor at an axis current value of a rotating coordinate system that rotates in accordance with a control angle that is a rotational angle used in a control. An addition angle calculation unit calculates an addition angle to be added to the control angle. A control angle calculation unit obtains, at every predetermined calculation cycle, a present value of the control angle by adding the addition angle that is calculated by the addition angle calculation unit to an immediately preceding value of the control angle. A torque detection unit detects a torque that is other than a motor torque and that is applied to a drive target driven by the motor. A command torque setting unit sets a command torque to be applied to the drive target.

Abstract: An electric power steering system includes a motor control device that controls driving of a motor based on an assist command value, the motor applying assist torque to a steering mechanism. The motor control device computes a first assist component based on steering torque and a vehicle speed. The motor control device computes a second assist component based on the steering torque and the first assist component. The motor control device computes the assist command value by adding the second assist component to the first assist component. The motor control device includes a road information compensation portion that adjusts the second assist component contained in the assist command value. A basic assist component computation portion computes the first assist component in accordance with a degree of adjustment of the second assist component.

Abstract: A motor control unit includes a detected steering torque correction unit that corrects the detected steering torque that is detected by a torque sensor and then subjected to a limitation process by a steering torque limiter. When the absolute value of the detected steering torque is equal to or smaller than a predetermined value, the detected steering torque correction unit corrects the detected steering torque to 0. When the absolute value of the detected steering torque is larger than the predetermined value, the detected steering torque correction unit outputs the detected steering torque without correction. A PI control unit calculates the addition angle based on the deviation of the control torque obtained through correction by the detected steering torque correction unit from the command steering torque.

Abstract: An electric power steering apparatus includes a controller that controls, based on an assist command value, driving of a motor used to apply assist torque to a steering mechanism. The controller calculates a first assist component based on a steering torque transmitted to the steering mechanism and calculates a steered angle command value based on the steering torque. The controller executes feedback control to cause a steered angle of steerable wheels to agree with the steered angle command value, thereby calculating a second assist component. The controller calculates the assist command value based on a value obtained by adding the assist components. The controller estimates a grip factor of the wheels on a road surface on which the wheels are traveling based on the steering torque, a first assist torque determined based on the first assist component, and a second assist torque determined based on the second assist component.

Abstract: A zero point change model executes banked road correspondence control when a vehicle travels on a banked road. By this control, a target turning angle when the total torque is zero can be changed from a neutral turning angle to a lower side of an inclined road surface. Thus, a steering angle of a steering wheel according to a banked road can be realized even if the driver does not apply steering torque during traveling on a banked road. Accordingly, the driver can obtain a suitable steering feeling when traveling on a banked road while achieving the target turning angle according to the total torque.

Abstract: An end determination unit determines that a steering apparatus is in an end touching state when an angle deviation, which is a difference between an actual turning angle and a target turning angle, exceeds a threshold. This angle deviation exceeds the threshold before a large axial force is generated in a steering shaft. Accordingly, is it possible to determine that the steering apparatus is in the end touching state more quickly.

Abstract: A F/B gain control unit computes a first change component by executing torque feedback control based on a torque deviation using a feedback gain that is computed by a F/B gain variable control unit. The F/B gain variable control unit computes one of two different feedback gains that correspond to a “first computation mode” in which the first change component is used as an addition angle and a “second computation mode” in which a value obtained by correcting the first change component by an estimated motor rotation angular velocity is used as the addition angle, respectively. A feedback gain used in the first computation mode is set such that a response at the feedback gain is higher than that at a feedback gain used in the second computation mode.

Abstract: The control apparatus calculates the first assist component on the basis of the steering torque. The control apparatus calculates the turning angle command value from the steering torque and the first assist component on the basis of the ideal model, executes turning angle feedback control for matching the actual turning angle with the turning angle command value, and calculates the second assist component. The control apparatus adds the second assist component to the first assist component to calculate the assist command value. When the deviation between the actual turning angle and the turning angle command value is out of the allowable range, the control apparatus changes the ideal model to remove the second assist component from the assist command value and enhance convergence of the turning angle feedback control system.

Abstract: A motor control signal output unit of an electric power steering system includes a feedback gain calculation unit (52), 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 (52). The feedback gain calculation unit (52) sets the feedback gains to large values (Kp=P0, Ki=I0) when the absolute value of an assist gradient (?) is equal to or smaller than a predetermined value (?0) (|?|??0). On the other hand, when the absolute value of the assist gradient (?) exceeds the predetermined value (?0) (|?|>?0), the feedback gain calculation unit (52) sets the feedback gains to small values (Kp=p1, Ki=I1:P1<P0, I1<I0).

Abstract: An electric power steering system includes a motor control device that controls, based on an assist command value, driving of a motor that gives an assist torque to a steering mechanism. The motor control device computes a first assist component based on a steering torque and a vehicle speed. A steered-angle command value is computed based on the steering torque and the first assist component, and a second assist component is computed by performing a feedback control that matches the steered angle with the steered-angle command value. The motor control device adds the second assist component to the first assist component so as to compute an assist command value. The motor control device includes a road information compensation portion that decreases an absolute value of the second assist component included in the assist command value when a skid is detected by a vehicle state detecting portion.

Abstract: A current command value computing section includes an integration control computing section. Based on an integration of the steering torque ?, the integration control computing section computes a steering torque integration control amount Iint*, which is a compensation component for increasing the assist force. The integration control computing section functions as a determining device that determines whether the vehicle is traveling forward in a straight line. When the determining device determines that the vehicle is traveling forward in a straight line, the integration control computing section outputs the steering torque integration control amount Iint* to an adder. The current command value computing section superimposes the steering torque integration control amount Iint* on a basic assist control amount Ias* computed by a basic assist control section, and outputs the obtained value, as a current command value Iq* corresponding to a target assist force, to an output section.

Abstract: A target pinion angle computation unit computes a target pinion angle on the basis of a basic assist component and a steering torque, and computes the target pinion angle so as to rapidly increase a steering reaction force when it is determined based on the target pinion angle that a rack shaft of a rack-and-pinion mechanism reaches a position near a limit of a movable range of the rack shaft. In an. EPS, a correction component for the basic assist component, which is necessary to increase the steering reaction force rapidly, is computed through execution of PID control for causing an actual pinion angle to coincide with the target pinion angle. Because the correction component is added to the basic assist component, the steering reaction force is increased rapidly when the rack shaft reaches the position near the limit of the movable range.

Abstract: An electric power steering system includes a motor control device that controls driving of a motor based on an assist command value, the motor applying assist torque to a steering mechanism. The motor control device computes a first assist component based on steering torque and a vehicle speed. The motor control device computes a second assist component based on the steering torque and the first assist component. The motor control device computes the assist command value by adding the second assist component to the first assist component. The motor control device includes a road information compensation portion that adjusts the second assist component contained in the assist command value. A basic assist component computation portion computes the first assist component in accordance with a degree of adjustment of the second assist component.

Abstract: An electric power steering system includes a motor control device that controls, based on an assist command value, driving of a motor that gives an assist torque to a steering mechanism. The motor control device computes a first assist component based on a steering torque and a vehicle speed. A steered-angle command value is computed based on the steering torque and the first assist component, and a second assist component is computed by performing a feedback control that matches the steered angle with the steered-angle command value. The motor control device adds the second assist component to the first assist component so as to compute an assist command value. The motor control device includes a road information compensation portion that decreases an absolute value of the second assist component included in the assist command value when a skid is detected by a vehicle state detecting portion.

Abstract: An assisting command value calculating unit calculates a first assisting factor on the basis of the value of a torque differential control volume added to a basic assist control volume based on a steering torque value, while increasing or decreasing, on the basis of an assisting gradient, the torque differential control volume based on a torque differential value. The pinion angle F/B control unit calculates a pinion angle command value, capable of being converted to a steering angle of the steering wheel, on the basis of the steering torque and the first assisting factor, and executes rotational angle feedback control. The assisting command value calculating unit calculates an assisting command value on the basis of the value of a second assisting factor, calculated by the pinion angle F/B control unit, added to the first assisting factor.

Abstract: A steering torque shift control amount calculation unit (31) calculates the steering torque shift control amount (?ts) by multiplying the basic shift amount (?ts_b) used as the basic compensation component by the transition coefficient (Kss). Then, the steering torque shift control amount (?ts) is subjected to the low-pass filter process in an abrupt change prevention processing unit (32). An abrupt change prevention processing unit (40) is provided in the steering torque shift control amount calculation unit (31). The transition coefficient (Kss) is subjected to the low-pass filter process in the abrupt change prevention processing unit (40). The cutoff frequency of the low-pass filter that forms the abrupt change prevention processing unit (40) is set to a value lower than the cutoff frequency of the low-pass filter that forms the abrupt change prevention processing unit (32) that executes the low-pass filter process on the torque shift control amount (?ts).

Abstract: A F/B gain control unit computes a first change component by executing torque feedback control based on a torque deviation using a feedback gain that is computed by a F/B gain variable control unit. The F/B gain variable control unit computes one of two different feedback gains that correspond to a “first computation mode” in which the first change component is used as an addition angle and a “second computation mode” in which a value obtained by correcting the first change component by an estimated motor rotation angular velocity is used as the addition angle, respectively. A feedback gain used in the first computation mode is set such that a response at the feedback gain is higher than that at a feedback gain used in the second computation mode.