Abstract: An electric power steering apparatus includes a control unit that calculates an assist controlled variable based on a plurality of types of state variables indicating steering statuses and controls a motor that serves as a generation source of an assist force applied to a steering mechanism of a vehicle based on the assist controlled variable. The control unit is configured to separately set limit values, which limit a change range of the assist controlled variable according to the respective state variables used to calculate the assist controlled variable, to the respective state variables, add up the limit values to generate ultimate limit value for the assist controlled variable, and perform limitation processing to limit the ultimate limit value for an assist controlled variable having a sign opposite to a sign of a steering torque that is one of the plurality of types of state variables.

Abstract: An electric power steering system includes a control unit configured to: compute an assist control amount (current amount), based on multiple kinds of state quantities indicating a steering state; control a motor based on the assist control amount, the motor being a source of assist force to be applied to a steering system of a vehicle; individually set, for the respective state quantities, limiting values that limit a variation range of the assist control amount, based on the respective state quantities used to compute the assist control amount; limit a value of the assist control amount using the limiting values; acquire a command value generated by a host control unit to change the assist control amount; and take the command value into account in setting of at least one of the limiting values, when executing control of the motor based on the assist control amount that reflects the command value.

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: In the vehicle power steering system, a first assist torque component is computed based on a steering torque and a vehicle speed. A target steered angle is computed based on the first assist torque component and the steering torque, and a second assist torque component is set based on the target steered angle and an actual steered angle. Then, the vehicle power steering system assists a steering operation by applying an assist torque Tas corresponding to the first assist torque component and the second assist torque component. Further, an ideal steered angle at which a vehicle is able to keep travelling in a lane is set based on image information on the lane captured by a camera, and a correction value is computed based on the deviation between the ideal steered angle and the actual steered angle. Then, the target steered angle is corrected by the correction value.

Abstract: Restriction values (upper limit and lower limit) for an assist control amount are set individually for each of state amounts including steering torque ? used to compute the assist control amount. A value obtained by summing such restriction values is set as a final restriction value for the assist control amount. Even though the assist control amount with an abnormal value is computed, the assist control amount is restricted to an appropriate value by the final restriction value. In addition, a transition is made from a primary assist control amount which is restricted to a secondary assist control amount computed separately from the primary assist control amount at the timing when a certain time elapses since the assist control amount is restricted. As the steering torque ? is increased, the speed of transition from the primary assist control amount to the secondary assist control amount is increased.

Abstract: In an electric power steering system, a vehicle reactive force model computes a correction spring reactive torque in such a manner that an elasticity component included in a steering reactive force is increased with an increase in a lateral acceleration. As the lateral acceleration increases, an increase in a basic drive torque is suppressed by a larger amount. By an amount by which the magnitude of the basic drive torque is suppressed, a target pinion angle computed by a target pinion angle computing unit decreases and a correction component for a basic assist component is decreased. A steering assist force is decreased, and a steering reactive force is increased with a decrease in the steering assist force. Thus, it is possible to obtain an appropriate steering reactive force based on the magnitude of the lateral acceleration.

Abstract: There is provided an electric power steering system that is able to generate a more appropriate current command value. Limits of an assist controlled variable, formed of multiple upper limits and multiple lower limits are individually set for multiple signals used to compute the assist controlled variable. The values obtained by adding the limits together are set as final limits of the assist controlled variable, that is, an upper limit and a lower limit. Thus, even if the assist controlled variable exhibiting an abnormal value is computed for some reason, the abnormal value of the assist controlled variable is limited to an appropriate value corresponding to each signal value by the final limits. By supplying the appropriate assist controlled variable to a motor control signal generating unit as a final current command value, an appropriate assist force is applied to a steering system.

Abstract: A steering system includes a motor control apparatus that controls driving of a motor based on an assist command value. The motor control apparatus includes an angle command value calculating unit that calculates an angle command value based on an input value including a steering torque, and calculates an assist component through execution of angle feedback control allowing a turning angle of a vehicle to follow the angle command value. The motor control apparatus calculates the assist command value based on the assist component. The motor control apparatus also calculates a correction value based on a deviation between a yaw rate of the vehicle and a yaw rate command value. An input value for the angle command value calculating unit is corrected based on the correction value.

Abstract: A control device in an electric power steering device calculates a first assist component based on steering torque and a vehicle speed. The control device also calculates a compensation component associated with an reverse input and calculates a steered angle command value based on an addition value of the compensation component and basic drive torque that is an addition value of the steering torque and the first assist component, produces a second assist component by performing steered angle feedback control that causes the steered angle of a vehicle to follow the steered angle command value. The control device controls drive of a motor based on an assist command value that is an addition value of the first assist component and the second assist component.

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 controller of an electric power steering system includes: a basic assist component computing unit (60) that computes a first assist component (Ta1*) based on a steering torque (Th); a steered angle command value computing unit (61) that computes a steered angle command value (?t*) based on the sum of the steering torque (Th) and the first assist component (Ta1*); and a steered angle feedback controller (62) that computes a second assist component (Ta2*) through feedback control on an actual steered angle (?t). The controller further includes: a correction component computing unit (65) that computes a correction component (Tc*) based on a steering angle (?s); and an assist command value computing unit (50) that computes an assist command value (Ta*) by subtracting the correction component (Tc*) from the sum of the first assist component (Ta1*) and the second assist component (Ta2*).

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 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 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: In an electric power steering system, a vehicle reactive force model computes a correction spring reactive torque in such a manner that an elasticity component included in a steering reactive force is increased with an increase in a lateral acceleration. As the lateral acceleration increases, an increase in a basic drive torque is suppressed by a larger amount. By an amount by which the magnitude of the basic drive torque is suppressed, a target pinion angle computed by a target pinion angle computing unit decreases and a correction component for a basic assist component is decreased. A steering assist force is decreased, and a steering reactive force is increased with a decrease in the steering assist force. Thus, it is possible to obtain an appropriate steering reactive force based on the magnitude of the lateral acceleration.

Abstract: In the vehicle power steering system, a first assist torque component is computed based on a steering torque and a vehicle speed. A target steered angle is computed based on the first assist torque component and the steering torque, and a second assist torque component is set based on the target steered angle and an actual steered angle. Then, the vehicle power steering system assists a steering operation by applying an assist torque Tas corresponding to the first assist torque component and the second assist torque component. Further, an ideal steered angle at which a vehicle is able to keep travelling in a lane is set based on image information on the lane captured by a camera, and a correction value is computed based on the deviation between the ideal steered angle and the actual steered angle. Then, the target steered angle is corrected by the correction value.

Abstract: A controller of an electric power steering system includes: a basic assist component computing unit (60) that computes a first assist component (Ta1*) based on a steering torque (Th); a steered angle command value computing unit (61) that computes a steered angle command value (?t*) based on the sum of the steering torque (Th) and the first assist component (Ta1*); and a steered angle feedback controller (62) that computes a second assist component (Ta2*) through feedback control on an actual steered angle (?t). The controller further includes: a correction component computing unit (65) that computes a correction component (Tc*) based on a steering angle (?s); and an assist command value computing unit (50) that computes an assist command value (Ta*) by subtracting the correction component (Tc*) from the sum of the first assist component (Ta1*) and the second assist component (Ta2*).

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: There is provided an electric power steering system that is able to generate a more appropriate current command value. Limits of an assist controlled variable, formed of multiple upper limits and multiple lower limits are individually set for multiple signals used to compute the assist controlled variable. The values obtained by adding the limits together are set as final limits of the assist controlled variable, that is, an upper limit and a lower limit. Thus, even if the assist controlled variable exhibiting an abnormal value is computed for some reason, the abnormal value of the assist controlled variable is limited to an appropriate value corresponding to each signal value by the final limits. By supplying the appropriate assist controlled variable to a motor control signal generating unit as a final current command value, an appropriate assist force is applied to a steering system.

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.