JP4487988B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus that detects a steering state and assists steering by generating an assist force according to the steering state by a motor.

  A conventional electric power steering apparatus detects a steering torque generated in a steering shaft by a torque sensor, and outputs it to a drive circuit for driving a motor based on the detected steering torque and a vehicle speed detected by other sensors. The current command value to be determined is determined, and a predetermined assist torque is generated in the motor.

  That is, the steering torque is detected from the torsion amount of a torsion bar or the like in which the input shaft connected to the steering wheel and the output shaft connected to the steering mechanism are connected to each other so as to be relatively rotatable, and a current is generated by the CPU based on the steering torque. A command value is calculated, and assist control is performed to cause the motor to generate an assist force according to the steering state.

By the way, in an electric power steering apparatus, not only assist control based on steering torque, vehicle speed, etc., but also control in consideration of the steering angle of the steering wheel, for example, self-aligning control may be required. Needs to input the steering angle data detected by the steering angle sensor of the steering shaft to the CPU.
Japanese Unexamined Patent Publication No. Sho 63-317702

  However, according to the conventional electric power steering device, the control device provided separately from the control device of the electric power steering device is used for the steering angle data detected by the steering angle sensor attached to the steering shaft. Must be received through. For this reason, various problems such as the need to separately provide data communication control between both control devices and the reliability of the data communication and ensuring fail-safe occur, and assist control based on the steering angle is generally difficult. It is considered to be.

The present invention has been made to solve the above-described problems, and an object thereof is to provide an electric power steering apparatus capable of performing assist control based on a steering angle.
Another object of the present invention is to provide an electric power steering apparatus capable of detecting an abnormality of the angle detection means.

In order to achieve the above object, in the electric power steering apparatus according to claim 1,
An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the first angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α10 of both angles Is a predetermined value α11 or more and a predetermined value α12 or less , and when the predetermined value α11 is the predetermined value α12 or less , or the rotation angle of the steering shaft detected by the first angle detection means, and the steering angle estimation means When the estimated rotation angle of the steering shaft estimated by the above is rotated in the opposite direction, the rotation angle of the steering shaft minus the estimated rotation angle of the steering shaft is divided by the estimated rotation angle of the steering shaft. The ratio β10, which is a value obtained by reversing the sign, represents the deviation caused by the backlash of the reducer as the absolute value of the estimated rotation angle of the steering shaft When more than a predetermined value β11 is divided by, for a first angle abnormality detecting means for detecting that an abnormality occurs in each of the first angle detection means, technically characterized in that it comprises.

In order to achieve the above object, the invention of claim 2
An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the first angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α10 of both angles is The steering shaft rotation angle detected when the state where the predetermined value α11 is equal to or greater than the predetermined value α12 and the predetermined value α11 is equal to or smaller than the predetermined value α12 continues for a predetermined time, When the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotates in a direction opposite to each other, a value obtained by subtracting the estimated rotation angle of the steering shaft from the rotation angle of the steering shaft The ratio β10, which is the value obtained by dividing the estimated rotation angle and reversing the sign, shows the deviation caused by the backlash of the reducer as the stearin. A first angle abnormality for detecting that an abnormality has occurred in each of the first angle detection means when a state where the value becomes equal to or greater than a predetermined value β11, which is a value divided by the absolute value of the estimated rotation angle of the shaft, continues for a predetermined time. Detection means;
It is a technical feature to have.

Furthermore, in order to achieve the above object, in the invention of claim 3,
An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the second angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α20 of both angles Is a predetermined value α21 or more and a predetermined value α22 or less , and when the predetermined value α21 is the predetermined value α22 or less , or the rotation angle of the steering shaft detected by the second angle detection means, and the steering angle estimation means When the estimated rotation angle of the steering shaft estimated by the above is rotated in the opposite direction, the rotation angle of the steering shaft minus the estimated rotation angle of the steering shaft is divided by the estimated rotation angle of the steering shaft. The ratio β20, which is a value obtained by reversing the sign, represents the deviation caused by the backlash of the speed reducer as the absolute value of the estimated rotation angle of the steering shaft. When divided by the predetermined value or more β21 is the value, and the second angle abnormality detecting means for detecting that an abnormality in each of the second angle detecting means is generated, technically characterized in that it comprises for.

Furthermore, in order to achieve the above object, in the invention of claim 4,
An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the second angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α20 of both angles is When the state where the predetermined value α21 is equal to or greater than the predetermined value α22 and is equal to or smaller than the predetermined value α22 continues for a predetermined time, or the rotation angle of the steering shaft detected by the second angle detection means When the estimated rotation angle of the steering shaft estimated by the steering angle estimating means rotates in the opposite direction, a value obtained by subtracting the estimated rotation angle of the steering shaft from the rotation angle of the steering shaft The ratio β20, which is a value obtained by dividing the estimated rotation angle and reversing the sign, shows the deviation caused by the backlash of the reducer as the stearin. A second angle abnormality for detecting that an abnormality has occurred in the second angle detecting means when a state where the predetermined value β21, which is a value divided by the absolute value of the estimated rotation angle of the shaft, continues for a predetermined time Detection means;
It is a technical feature to have.

Further, according to a fifth aspect of the present invention, in the first or second aspect , the predetermined value α11, the predetermined value α12, and the predetermined value β11 are the rotation angle of the steering shaft detected by the first angle detecting means or the steering. It is a technical feature that changes based on the estimated rotation angle of the steering shaft estimated by the angle estimation means.

Furthermore, in the invention of claim 6 , in claim 3 or 4 , the predetermined value α21, the predetermined value α22 and the predetermined value β21 are the rotation angle of the steering shaft detected by the second angle detecting means or the It is a technical feature that changes based on the estimated rotation angle of the steering shaft estimated by the steering angle estimation means.

According to the first aspect of the present invention, the steering shaft and the steering mechanism shaft are connected to each other so as to be relatively rotatable by the elastic member, and the assist force of the motor is transmitted to the steering mechanism shaft at a predetermined reduction ratio by the speed reducer. Is detected by the first angle detection means, and the rotation angle of the steering mechanism shaft is detected by the second angle detection means. Then, the assist force determining means determines the assist force generated by the motor based on one of the rotation angle of the steering shaft and the rotation angle of the steering mechanism shaft, and the steering detected by the first angle detection means. When the rotation angle of the shaft and the estimated rotation angle of the steering shaft estimated by the steering angle estimating means rotate in the same direction, the ratio α10 of both angles is a predetermined value α11 or more and a predetermined value α12 or less and a predetermined value α11 When the rotation angle of the steering shaft detected by the first angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in opposite directions. The sign is inverted by subtracting the estimated rotation angle of the steering shaft from the rotation angle of the steering shaft and dividing it by the estimated rotation angle of the steering shaft. When the ratio β10, which is the value, is equal to or greater than a predetermined value β11, which is a value obtained by dividing the deviation caused by the backlash of the reduction gear by the absolute value of the estimated rotation angle of the steering shaft, an abnormality has occurred in each of the first angle detection means Detect that. As a result, the rotation angle of the steering shaft can be detected, and the torsion amount of the elastic member can be detected as the torsion angle from either the rotation angle of the steering shaft or the rotation angle of the steering mechanism shaft. Assist control can be performed in consideration of the steering angle of the steering wheel. Therefore, there is an effect that assist control based on the steering angle can be performed. Further, the first angle detection means sets a ratio (α10, β10) between the rotation angle of the steering shaft and the estimated rotation angle of the steering shaft according to the rotation direction (α10 is α11 or more and α12 or less). , Β10 is detected in comparison with β11 or more), so that there is an effect that the abnormality of the angle detection means can be detected more accurately.

In the second aspect of the invention, the steering shaft and the steering mechanism shaft are connected to each other by an elastic member so as to be relatively rotatable, and the assist force of the motor is transmitted to the steering mechanism shaft at a predetermined reduction ratio by the speed reducer. Is detected by the first angle detection means, and the rotation angle of the steering mechanism shaft is detected by the second angle detection means. Then, the assist force determining means determines the assist force generated by the motor based on one of the rotation angle of the steering shaft and the rotation angle of the steering mechanism shaft, and the steering detected by the first angle detection means. When the rotation angle of the shaft and the estimated rotation angle of the steering shaft estimated by the steering angle estimating means rotate in the same direction, the ratio α10 of both angles is a predetermined value α11 or more and a predetermined value α12 or less and a predetermined value α11 When the state in which the value becomes equal to or less than the predetermined value α12 continues for a predetermined time, or the rotation angle of the steering shaft detected by the first angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means When turning in opposite directions, the steering shaft rotation angle minus the estimated rotation angle of the steering shaft is A state in which the ratio β10, which is a value obtained by dividing by a constant rotation angle and reversing the sign, is equal to or greater than a predetermined value β11, which is a value obtained by dividing the deviation caused by the backlash of the reduction gear by the absolute value of the estimated rotation angle of the steering shaft. When the time continues, it is detected that an abnormality has occurred in the first angle detection means. As a result, the rotation angle of the steering shaft can be detected, and the torsion amount of the elastic member can be detected as the torsion angle from either the rotation angle of the steering shaft or the rotation angle of the steering mechanism shaft. Assist control can be performed in consideration of the steering angle of the steering wheel. Therefore, there is an effect that assist control based on the steering angle can be performed. Further, the first angle detection means sets a ratio (α10, β10) between the rotation angle of the steering shaft and the estimated rotation angle of the steering shaft according to the rotation direction (α10 is α11 or more and α12 or less). , Β10 is detected continuously for a predetermined time as compared with β11 or more), so that it is possible to detect an abnormality of the angle detection means more accurately.

In the third aspect of the invention, the steering shaft and the steering mechanism shaft are connected to each other by an elastic member so as to be relatively rotatable, and the assist force of the motor is transmitted to the steering mechanism shaft at a predetermined reduction ratio by the speed reducer. Is detected by the first angle detection means, and the rotation angle of the steering mechanism shaft is detected by the second angle detection means. The assist force determining means determines the assist force generated by the motor based on one of the rotation angle of the steering shaft and the rotation angle of the steering mechanism shaft, and the steering detected by the second angle detection means. When the rotation angle of the shaft and the estimated rotation angle of the steering shaft estimated by the steering angle estimating means rotate in the same direction, the ratio α20 of both angles is a predetermined value α21 or more and a predetermined value α22 or less and a predetermined value α21 When the rotation angle of the steering shaft detected by the second angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in opposite directions. The sign is inverted by subtracting the estimated rotation angle of the steering shaft from the rotation angle of the steering shaft and dividing it by the estimated rotation angle of the steering shaft. When the ratio β20, which is the value, is equal to or greater than a predetermined value β21, which is a value obtained by dividing the deviation caused by the backlash of the reduction gear by the absolute value of the estimated rotation angle of the steering shaft, an abnormality has occurred in the second angle detection means, respectively. Detect that. As a result, the rotation angle of the steering shaft can be detected, and the torsion amount of the elastic member can be detected as the torsion angle from either the rotation angle of the steering shaft or the rotation angle of the steering mechanism shaft. Assist control can be performed in consideration of the steering angle of the steering wheel. Therefore, there is an effect that assist control based on the steering angle can be performed. Further, the second angle detection means sets a ratio (α20, β20) between the rotation angle of the steering shaft and the estimated rotation angle of the steering shaft according to the rotation direction (α20 is α21 or more and α22 or less). , Β20 is detected in comparison with β21 or more), so that it is possible to detect the abnormality of the angle detection means more accurately.

In the invention of claim 4, the steering shaft and the steering mechanism shaft are connected to each other by an elastic member so as to be relatively rotatable, and the assist force of the motor is transmitted to the steering mechanism shaft at a predetermined reduction ratio by the speed reducer, so that the rotation angle of the steering shaft Is detected by the first angle detection means, and the rotation angle of the steering mechanism shaft is detected by the second angle detection means. The assist force determining means determines the assist force generated by the motor based on one of the rotation angle of the steering shaft and the rotation angle of the steering mechanism shaft, and the steering detected by the second angle detection means. When the rotation angle of the shaft and the estimated rotation angle of the steering shaft estimated by the steering angle estimating means rotate in the same direction, the ratio α20 of both angles is a predetermined value α21 or more and a predetermined value α22 or less and a predetermined value α21 When the state in which the value is equal to or less than the predetermined value α22 continues for a predetermined time, or the rotation angle of the steering shaft detected by the second angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means When turning in opposite directions, the steering shaft rotation angle minus the estimated steering shaft rotation angle is the steering shaft rotation angle. A state in which the ratio β20, which is a value obtained by dividing by a constant rotation angle and reversing the sign, becomes equal to or greater than a predetermined value β21, which is a value obtained by dividing the deviation caused by the backlash of the reducer by the absolute value of the estimated rotation angle of the steering shaft for a predetermined time When the operation continues, it is detected that an abnormality has occurred in the second angle detection means. As a result, the rotation angle of the steering shaft can be detected, and the torsion amount of the elastic member can be detected as the torsion angle from either the rotation angle of the steering shaft or the rotation angle of the steering mechanism shaft. Assist control can be performed in consideration of the steering angle of the steering wheel. Therefore, there is an effect that assist control based on the steering angle can be performed. Further, the second angle detection means sets a ratio (α20, β20) between the rotation angle of the steering shaft and the estimated rotation angle of the steering shaft according to the rotation direction (α20 is α21 or more and α22 or less). , Β20 is detected continuously for a predetermined time compared to β21 or more), and there is an effect that the abnormality of the second angle detection means can be detected more accurately.

In the invention of claim 5 , the predetermined value α11, the predetermined value α12 and the predetermined value β11 are the rotation angle of the steering shaft detected by the first angle detection means or the estimated rotation angle of the steering shaft estimated by the steering angle estimation means. Therefore, it is possible to determine whether or not there is an abnormality in the first angle detection means in response to a change in the rotation angle of the steering shaft or the estimated rotation angle. Therefore, there is an effect that the abnormality of the first angle detection means can be detected more accurately.

In the invention of claim 6 , the predetermined value α21, the predetermined value α22 and the predetermined value β21 are the rotation angle of the steering shaft detected by the second angle detection means or the estimated rotation angle of the steering shaft estimated by the steering angle estimation means. Therefore, it is possible to determine whether there is an abnormality in the second angle detection means in response to a change in the rotation angle of the steering shaft or the estimated rotation angle. Therefore, there is an effect that the abnormality of the second angle detection means can be detected more accurately.

  Hereinafter, an embodiment of an electric power steering apparatus of the present invention will be described with reference to the drawings. In the following embodiments, an example in which the electric power steering apparatus of the present invention is applied to an electric power steering apparatus for a vehicle such as an automobile will be described.

  First, the main configuration of the electric power steering apparatus 10 will be described with reference to FIG. 1 as a technique that is a base of the embodiment of the electric power steering apparatus of the present invention.

  As shown in FIG. 1, an electric power steering apparatus 10 mainly includes a steering wheel 11, a steering shaft 12, a pinion shaft 13, a torsion bar 14, angle sensors 15, 16, a speed reducer 17, a rack and pinion 18, and a motor. The rotation angle sensor 19, the motor M, the ECU 20, and the like are configured to detect a steering state by the steering wheel 11, and generate assist force corresponding to the steering state by the motor M to assist the steering.

That is, one end side of the steering shaft 12 is connected to the steering wheel 11, and one end side of the torsion bar 14 is connected to the other end side of the steering shaft 12. One end side of the pinion shaft 13 is connected to the other end side of the torsion bar 14, and a pinion gear of a rack pinion 18 is connected to the other end side of the pinion shaft 13. Further, the steering shaft 12 and the pinion shaft 13 are respectively provided with angle sensors 15 and 16 that can detect the respective rotation angles (steering angles θ ₁ and θ ₂ ) in an absolute or relative manner. Electrically connected. In addition, as these angle sensors 15 and 16, absolute angle sensors, such as an absolute encoder and a resolver, and relative angle sensors, such as an incremental encoder, are used, for example.

  Since both ends of the torsion bar 14 are provided with mechanical rotation limiting portions called manual stoppers, the torsion angle of the torsion bar 14 is restricted to a fixed angle (for example, ± 6 °). As a result, the torsion bar 14 is prevented from being damaged due to an excessive increase in the amount of twist.

As a result, the steering shaft 12 and the pinion shaft 13 can be connected to each other by the torsion bar 14 so as to be relatively rotatable, and the rotation angle (steering angle θ ₁ ) of the steering shaft 12 is also detected by the angle sensor 15 and the pinion shaft 13. The rotation angle (steering angle θ ₂ ) can be detected by the angle sensor 16. Therefore, it is possible to detect a steering angle theta ₁ by the angle sensor 15 the rotation angle of the steering shaft 12, a steering angle of the pinion shaft 13 by the steering angle theta ₁ and the angle sensor 16 of the steering shaft 12 by the angle sensor 15 theta ₂ The torsion amount of the torsion bar 14 can be detected as the torsion angle from the angle difference (deviation) and the angle ratio.

  A reduction gear 17 that transmits a driving force generated by the motor M at a predetermined reduction ratio is engaged with the pinion shaft 13 via a gear (not shown). The driving force, that is, the assisting force can be transmitted to the pinion shaft 13. Further, the motor M is also provided with a motor rotation angle sensor 19 capable of detecting the rotation angle, and the motor rotation angle sensor 19 is also electrically connected to the ECU 20. As the motor rotation angle sensor 19, an absolute angle sensor such as an absolute encoder or a resolver, or a relative angle sensor such as an incremental encoder is used.

  Thereby, since the rotation angle signals detected by the angle sensors 15 and 16 and the motor rotation angle sensor 19 can be sent to the ECU 20, the ECU 20 generates assist force generated by the motor M based on these rotation angle signals. It can be determined as follows. It should be noted that unillustrated wheels are connected to both sides of the rack and pinion 18 via tie rods or the like.

Next, the electrical configuration and operation of the ECU 20 and the like constituting the electric power steering apparatus 10 will be described with reference to FIG.
As shown in FIG. 2, the ECU 20 is mainly configured by an assist torque determining unit 21, a current control unit 23, and the like. Specifically, the ECU 20 is configured by a CPU, a memory element, various interface circuits, and the like.

The assist torque determining means 21 determines the assist force generated by the motor M based on the steering angle θ ₁ detected by the angle sensor 15 and the steering angle θ ₂ detected by the angle sensor 16. For example, the steering angle theta _1, the theta ₂ of the angular difference (deviation) and angle assisted previously set corresponding to such ratio current instruction I _A ^* maps and predetermined arithmetic processing and the like, the assist current command I _A ^* Looking for.

Further, in the assist torque determining means 21, the steering angles θ ₁ , θ ₂ apart from the map of the assist current command I _A ^* set in advance corresponding to such an angle difference between the steering angles θ ₁ , θ _{2, etc. A} map for obtaining the assist current command I _A ^* from either one of them, a predetermined calculation process, or the like is provided. Thereby, the twist amount of the torsion bar 14 can also be detected as the twist angle from either the steering angle θ ₁ or the steering angle θ ₂ .

The current control means 23 converts the assist current command I _A ^* determined by the assist torque determination means 21 into a voltage based on the actual current I _A flowing through the motor M, and outputs a voltage command V ^* . That is, the current control means 23 is controlled so as to output a voltage command V ^* as a target by negative feedback real current I _A flowing through the motor M detected by the motor current detecting means 27.

The motor driving means 25 is constituted by a PWM circuit 24 and switching elements Q1 to Q4. The PWM circuit 24 is a pulse width modulation circuit realized by hardware different from that of the ECU 20, and outputs a pulse signal having a pulse width corresponding to the voltage command V ^* output from the current control means 23 for each of the U phase and the V phase. It is comprised so that it can output. Thereby, since the U-phase and V-phase pulse signals corresponding to the gates of the switching elements Q1 to Q4 connected to the output side can be given, the switching elements Q1 to Q4 are turned on and off according to the pulse width. Thus, the motor M can be arbitrarily controlled.

As described above, in the electric power steering apparatus 10 according to the technology serving as the base of the present embodiment, the steering shaft 12 and the pinion shaft 13 are coupled to each other by the torsion bar 14 so as to be relatively rotatable, and the steering angle θ _{1 of the} steering shaft 12 is obtained. Is detected by the angle sensor 15, and the steering angle θ ₂ of the pinion shaft 13 is detected by the angle sensor 16. Then, the assist torque determining means 21 determines the assist force generated by the motor M based on at least one of the steering angle θ ₁ of the steering shaft 12 and the steering angle θ ₂ of the pinion shaft 13. Thus, it is possible to detect the steering angle theta ₁ of the steering shaft 12, angle twist the torsion amount of the torsion bar 14 from at least one of a steering angle theta ₂ of the steering angle theta ₁ and the pinion shaft 13 of the steering shaft 12 Therefore, for example, when self-aligning control is required, assist control in consideration of the steering angle of the steering wheel 11 can be performed. Therefore, there is an effect that assist control based on the steering angle can be performed.

[First modification]
Next, an electric power steering apparatus according to a first modification example (hereinafter referred to as “first modification example”) of the electric power steering apparatus 10 will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, in the electric power steering apparatus of the first modified example, the deviation (θ ₁ −θ ₂₎ between the steering angle θ ₁ detected by the angle sensor 15 and the steering angle θ ₂ detected by the angle sensor 16. ) determined by the calculating means 33 a twist angle [Delta] [theta] _H of the torsion bar 14 is, calculates the assist current command I _a ^* by the assist torque determining means 31 based on the twist angle [Delta] [theta] _H. This point differs from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU according to the first modification. Therefore, the mechanical configuration of the electric power steering apparatus according to the first modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This is explained with the aid of it.

As shown in FIG. 4, in the first modification, the assist torque determination unit 31 includes a phase compensation unit 31 a and an assist current calculation unit 31 b. Thereby, the deviation between the steering angle theta ₂ of the steering angle theta ₁ and the pinion shaft 13 of the steering shaft 12 (θ ₁ -θ _2), i.e. twist angles [Delta] [theta] _H of the torsion bar 14 is inputted to the assist torque determining means 31 After phase compensation for the twist angle Δθ _H of the torsion bar 14 by the phase compensation unit 31a, the assist current computation unit 21b uses the assist current computation unit 21b based on the phase compensation torsion angle Δθ _H 'to map or perform predetermined computation processing. Command I _A ^* is calculated. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 21a, T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

In this way, the electric power steering apparatus according to a first modification example, relatively rotatably connected by a torsion bar 14 and the steering shaft 12 and the pinion shaft 13, the angle sensor 15 the steering angle theta ₁ of the steering shaft 12, Further, the steering angle θ ₂ of the pinion shaft 13 is detected by the angle sensor 16. Then, the assist torque determining means 31, on the basis of the deviation between the steering angle theta ₂ of the steering angle theta ₁ and the pinion shaft 13 of the steering shaft 12 (θ ₁ -θ _2), to determine the assist force generated by the motor M (See FIGS. 1 and 3). Thus, it is possible to detect the steering angle theta ₁ of the steering shaft 12, can be detected as a torsion angle [Delta] [theta] _H torsion amount of the torsion bar 14, in a case like that is for instance required self aligning control Assist control in consideration of the steering angle of the steering wheel 11 can be performed. Therefore, as with the electric power steering apparatus 10 described above, there is an effect that assist control based on the steering angle can be performed.

[Second modification]
Next, an electric power steering apparatus according to a second modification example (hereinafter referred to as “second modification example”) of the electric power steering apparatus 10 described above will be described with reference to FIGS. 5 and 6.

As shown in FIG. 5, the electric power steering apparatus according to the second modified example includes an angle sensor abnormality detection unit 43 that detects an abnormality of each of the angle sensors 15 and 16. When an abnormality is detected in one of the angle sensors 15 and 16, the assist torque determining means 41 calculates the assist current command I _A ^* based on the steering angle θ detected by the normal angle sensor. This point is different from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU of the second modified example. Therefore, the mechanical configuration of the electric power steering apparatus according to the second modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This will be explained with assistance. FIG. 5 shows an example in which an abnormality occurs in the angle sensor 16.

As shown in FIG. 5, the electric power steering apparatus of the second modified example includes an angle sensor abnormality detection unit 43, and the angle sensor abnormality detection unit 43 detects an abnormality of the angle sensors 15 and 16. The detection signal can be sent to the assist torque determining means 41. The abnormality detection of the angle sensors 15 and 16 is performed by, for example, timer interruption processing performed at predetermined intervals, and the values of the rotation angles (steering angles θ ₁ and θ ₂ ) output from the angle sensors 15 and 16 are constant. This is carried out by monitoring whether it is within a range (for example, 0 ° or more and 12 ° or less). If it is not within the predetermined range, it is determined that an abnormality has occurred in the angle sensor.

As shown in FIG. 6, the assist torque determining means 41 includes a phase compensator 41 a (41 c) and an assist current calculator 41 b (41 d), and steering angles θ ₁ and θ input from the angle sensors 15 and 16. It is prepared for every _two . That is, the phase for each steering angle θ ₁ , θ ₂ so that the assist current command I _A ^* can be calculated based on one steering angle input from the normal angle sensor of the angle sensors 15, 16. Compensators 41a and 41c and assist current calculators 41b and 41d are configured.

Thus, for example, as shown in FIG. 5, when an abnormality of the angle sensor 16 is detected by the angle sensor abnormality detection means 43 (a cross mark of the angle sensor 16 shown in FIG. 5), the steering from the normal angle sensor 15 is performed. Since the angle θ ₁ is input, after phase compensation for the steering angle θ ₁ by the phase compensation unit 41a, the assist current calculation unit 41b performs a map, predetermined calculation processing, or the like based on the phase compensated steering angle θ ₁ ′. To calculate the assist current command I _A ^* . Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 41a (41c), T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

On the other hand, when an abnormality of the angle sensor 15 is detected by the angle sensor abnormality detecting means 43, since the steering angle theta ₂ is inputted from the normal angle sensor 16, the phase compensation for the steering angle theta ₂ by the phase compensating unit 41c After that, the assist current calculation unit 41d calculates an assist current command I _A ^* by a map, predetermined calculation processing, or the like based on the phase-compensated steering angle θ ₂ ′.

Note that the map used in the assist current calculation unit 41b (41d), predetermined calculation processing, and the like determine the assist current command I _A ^* from _one normal steering angle θ ₁ (θ ₂ ). Therefore, there is a possibility that the accuracy of the calculated assist current command I _A ^* may be lower than that by the assist current calculation unit 31b described above. It is also a feature of the electric power steering apparatus of the second modified example that the assist current by the motor M can be generated by obtaining the assist current command I _A ^* .

As described above, in the electric power steering apparatus according to the second modification, when the angle sensor abnormality detection unit 43 detects an abnormality in one of the angle sensor 15 and the angle sensor 16, the assist torque determination unit 41 is normal. The assist force generated by the motor M is determined based on the steering angle θ ₁ (θ ₂ ) detected by the other (see FIGS. 1 and 5). Thus, even if an abnormality occurs in either the angle sensor 15 or the angle sensor 16, the assist force can be determined based on the steering angle θ ₁ (θ ₂ ) detected by the other normal sensor. Therefore, even if an abnormality occurs in one angle sensor, there is an effect that appropriate assist control can be performed.

[Third Modification]
Next, an electric power steering apparatus according to a third modification example (hereinafter referred to as “third modification example”) of the electric power steering apparatus 10 described above will be described with reference to FIGS. 7 and 8.

As shown in FIG. 7, in the electric power steering apparatus according to the third modified example, an angle sensor abnormality detecting means 53 for detecting abnormality of each of the angle sensors 15 and 16, and a vehicle speed sensor for detecting or estimating the vehicle speed V 55, and when the angle sensor abnormality detecting means 53 detects an abnormality in one of the angle sensors 15 and 16, the steering angle θ detected by the normal angle sensor and the vehicle speed sensor 55 Based on the estimated vehicle speed V, the assist current determining means 51 calculates an assist current command I _A ^* . This point is different from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU according to the third modified example. FIG. 7 shows an example in which an abnormality has occurred in the angle sensor 16.

Further, compared with the electrical configuration of the electric power steering apparatus of the second modified example described above, the vehicle is provided with a vehicle speed sensor 55, and based on the vehicle speed V detected or estimated by the vehicle speed sensor 55, the assist torque determining means 51 differs in that the assist current command I _A ^* is calculated. Therefore, the mechanical configuration of the electric power steering apparatus according to the third modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This will be explained with assistance.

As shown in FIG. 7, the electric power steering apparatus of the third modified example includes an angle sensor abnormality detection means 53 and a vehicle speed sensor 55.
The angle sensor abnormality detection means 53 can detect an abnormality of the angle sensors 15 and 16 and send a detection signal to the assist torque determination means 41, similarly to the angle sensor abnormality detection means 43 described in the second modification. It is configured. For example, the values of the rotation angles (steering angles θ ₁ and θ ₂ ) output from the angle sensors 15 and 16 are within a certain range (for example, 0 ° or more and 20 ° or less) by timer interruption processing performed at predetermined intervals. If it is not within the predetermined range, it is determined that an abnormality has occurred in the angle sensor.

  On the other hand, the vehicle speed sensor 55 can detect or estimate the vehicle speed V, and is configured to send a detection signal or an estimation signal to the assist torque determining means 41. The detection or estimation of the vehicle speed V is also executed by, for example, timer interruption processing performed at predetermined intervals, as in the case of detecting the abnormality of the angle sensors 15 and 16.

As shown in FIG. 8, the assist torque determination means 51 includes a phase compensation unit 51a (51c), an assist current calculation unit 51b (51d), a vehicle speed correction gain calculation unit 51e, and a multiplier 51f. Of these, the phase compensator 51a (51c) and the assist current calculator 51b (51d) are similar to the phase compensators 41a and 41c and the assist current calculators 41b and 41d described in the second modified example. Among them, the steering current is prepared for each of the steering angles θ ₁ and θ ₂ so that the assist current command I _A0 ^* can be calculated based on one steering angle input from a normal angle sensor.

In addition, the vehicle speed correction gain calculation unit 51e has a predetermined characteristic corresponding to the vehicle speed V detected or estimated by the vehicle speed sensor 55, for example, a characteristic that the vehicle speed correction gain G _V decreases with an increase in the vehicle speed V above a certain level ( 0 ≦ G _V ≦ 1) vehicle speed correction gain G _V output to be mapped or a predetermined arithmetic processing or the like having a are set in advance. Then, the vehicle speed correction gain G _V output from the vehicle speed correction gain calculation unit 51e is multiplied by the assist current command I _A0 ^* output from the assist current calculation unit 51b (51d) via the multiplier 51f to obtain the assist current. Output as command I _A ^* . That is, the assist current command I _A ^* based on the vehicle speed is output.

Thus, for example, as shown in FIG. 7, when an abnormality of the angle sensor 16 is detected by the angle sensor abnormality detection means 53 (a cross mark of the angle sensor 16 shown in FIG. 7), the steering from the normal angle sensor 15 is performed. Since the angle θ ₁ is input, the assist current command I _A0 ^* is calculated by the phase compensation unit 51 a and the assist current calculation unit 51 b by a map, a predetermined calculation process, and the like, and the vehicle speed correction gain is _{added to the} assist current command I _A0 ^*. The assist current command I _A ^* is output by multiplying the vehicle speed correction gain G _V corresponding to the vehicle speed V by the calculation unit 51e. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensator 51a (51c), T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

Map other hand, when an abnormality of the angle sensor 15 is detected by the angle sensor abnormality detecting means 53, since the steering angle theta ₂ is inputted from the normal angle sensor 16, the phase compensation unit 51c and the assist current calculation unit 51d calculating an assist current command I _A0 ^* at or a predetermined arithmetic processing and the like, the assist current command I by multiplying the vehicle speed correction gain G _V corresponding to the vehicle speed V to the assist current command I _A0 ^* by the vehicle speed correction gain calculation unit 51e _A ^* is output.

Note that the map used in the assist current calculation unit 51b (51d), predetermined calculation processing, and the like determine the assist current command I _A0 ^* from _one normal steering angle θ ₁ (θ ₂ ). For this reason, the accuracy of the calculated assist current command I _A ^* may be lower than that by the assist current calculation unit 31b described above, but temporarily until the other angle sensor that has failed is recovered. An assist force by the motor M can be generated by obtaining the assist current command I _A ^* .

As described above, in the electric power steering apparatus according to the third modification, when the angle sensor abnormality detection unit 53 detects abnormality in either the angle sensor 15 or the angle sensor 16, the assist torque determination unit 51 is normal. The assist force generated by the motor M is determined based on the steering angle θ ₁ (θ ₂ ) detected by the other and the vehicle speed V detected or estimated by the vehicle speed sensor 55 (see FIGS. 1 and 7). . Thus, even if an abnormality occurs in one of the angle sensor 15 and the angle sensor 16, it is generated by the motor M based on the vehicle speed V in addition to the steering angle θ ₁ (θ ₂ ) detected by the other normal sensor. The assist force can be determined. Therefore, even if an abnormality occurs in one angle sensor, there is an effect that appropriate assist control can be performed.

[Fourth modification]
Next, an electric power steering apparatus according to a fourth modification example (hereinafter referred to as “fourth modification example”) of the electric power steering apparatus 10 described above will be described with reference to FIGS. 9 and 10.

As shown in FIG. 9, in the electric power steering apparatus according to the fourth modified example, the angle sensor abnormality detecting means 63 for detecting the abnormality of each of the angle sensors 15, 16 and the angular velocity (dθ _S / steering angle speed estimation means 65 for estimating dt), and when the angle sensor abnormality detection means 63 detects an abnormality in one of the angle sensors 15 and 16, the steering angle detected by the normal angle sensor Based on θ and the angular velocity (dθ _S / dt) of the steering wheel 11 estimated by the steering angular velocity estimating means 65, the assist torque determining means 61 calculates an assist current command I _A ^* . This point is different from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU of the fourth modified example. FIG. 9 shows an example in which an abnormality occurs in the angle sensor 16.

Further, comparing the electrical configuration of the electric power steering apparatus of the second modified example described above, the steering angular velocity estimating means 65 is provided, and the angular velocity (dθ _S / The difference is that the assist current command I _A ^* is calculated by the assist torque determination means 61 based on dt). Therefore, the mechanical configuration of the electric power steering apparatus according to the fourth modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This is explained with the aid of it.

As shown in FIG. 9, the electric power steering apparatus of the fourth modified example includes an angle sensor abnormality detection unit 63 and a steering angular velocity estimation unit 65.
The angle sensor abnormality detection means 63 can detect an abnormality of the angle sensors 15 and 16 and send a detection signal to the assist torque determination means 41, as with the angle sensor abnormality detection means 43 described in the second modification. The rotation angle (steering angles θ ₁ , θ ₂ ) output from the angle sensors 15, 16 is within a certain range (for example, 0 ° or more and 20 °, for example) by timer interruption processing performed at predetermined intervals, for example. Or less). If it is not within the predetermined range, it is determined that an abnormality has occurred in the angle sensor.

On the other hand, the steering angular velocity estimation means 65 can estimate the steering angular velocity (dθ _S / dt) of the steering wheel 11, and is estimated from the amount of angular variation per unit time of the steering angle θ ₁ detected by the angle sensor 15, for example. The estimation signal can be sent to the assist torque determination means 41. The estimation of the steering angular velocity (dθ _S / dt) is also executed by, for example, timer interruption processing performed at predetermined intervals, as in the case of detecting the abnormality of the angle sensors 15 and 16.

  As shown in FIG. 10, the assist torque determining means 61 includes a phase compensation unit 61a (61c), an assist current calculation unit 61b (61d), a steering angular velocity correction gain calculation unit 61e, and a multiplier 61f. Among them, the phase compensation unit 61a (61c) and the assist current calculation unit 61b (61d) are the same as the phase compensation units 51a and 51c and the assist current calculation units 51b and 51d described in the third modification, respectively. Then, these descriptions are omitted.

Further, the steering angular velocity correction gain calculator 61e responds to an increase in a predetermined characteristic, for example, the steering angular velocity (dθ _S / dt) corresponding to the steering angular velocity (dθ _S / dt) estimated by the steering angular velocity estimation means 65. A map that can output the steering angular velocity correction gain G _S having a characteristic (0 ≦ G _S ≦ 1) in which the steering angular velocity correction gain G _S increases, a predetermined calculation process, and the like are set in advance. The steering angular velocity correction gain G _S output from the steering angular velocity correction gain calculation unit 61e is multiplied by the assist current command I _A0 ^* output from the assist current calculation unit 61b (61d) via the multiplier 61f. It is output as an assist current command I _A ^* . That is, the assist current command I _A ^* based on the steering angular velocity is output.

Thus, for example, as shown in FIG. 9, when an abnormality of the angle sensor 16 is detected by the angle sensor abnormality detection means 63 (a cross mark of the angle sensor 16 shown in FIG. 9), the steering from the normal angle sensor 15 is performed. Since the angle θ ₁ is input, the assist current command I _A0 ^* is calculated by a map, a predetermined calculation process, and the like by the phase compensation unit 61a and the assist current calculation unit 61b, and the steering angular velocity correction is performed on the assist current command I _A0 ^*. The assist current command I _A ^* is output by multiplying the steering angular velocity correction gain G _S corresponding to the steering angular velocity (dθ _S / dt) by the gain calculator 61e. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 61a (61c), T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

Map other hand, when an abnormality of the angle sensor 15 is detected by the angle sensor abnormality detecting means 63, since the steering angle theta ₂ is inputted from the normal angle sensor 16, the phase compensation unit 61c and the assist current calculation unit 61d The assist current command I _A0 ^* is calculated by a predetermined calculation process or the like, and the steering angular velocity correction gain G corresponding to the steering angular velocity (dθ _S / dt) by the steering angular velocity correction gain calculation unit 61e is calculated based on the assist current command I _A0 ^*. Multiply _S to output the assist current command I _A ^* .

The map used in the assist current calculation unit 61b (61d), the predetermined calculation process, and the like are for _{obtaining the} assist current command I _A0 ^* from _one normal steering angle θ ₁ (θ ₂ ). For this reason, the accuracy of the calculated assist current command I _A ^* may be lower than that by the assist current calculation unit 31b described above, but temporarily until the other angle sensor that has failed is recovered. An assist force by the motor M can be generated by obtaining the assist current command I _A ^* .

As described above, in the electric power steering apparatus according to the fourth modification, when the angle sensor abnormality detection unit 63 detects an abnormality in one of the angle sensor 15 and the angle sensor 16, the assist torque determination unit 61 is normal. Assist force generated by the motor M based on the steering angle θ ₁ (θ ₂ ) detected by the other and the steering angular velocity (dθ _S / dt) of the steering wheel 11 estimated by the steering angular velocity estimation means 65. Determine (see FIGS. 1 and 9). As a result, even if an abnormality occurs in one of the angle sensor 15 and the angle sensor 16, it is based on the steering angular velocity (dθ _S / dt) in addition to the steering angle θ ₁ (θ ₂ ) detected by the other normal sensor. Since the assist force generated by the motor M is determined, the assist control corresponding to the angular velocity (dθ _S / dt) of the steering wheel 11 can be performed. Therefore, even if an abnormality occurs in one angle sensor, there is an effect that appropriate assist control can be performed.

[Fifth modification]
Next, an electric power steering apparatus according to a fifth modification example (hereinafter referred to as “fifth modification example”) of the electric power steering apparatus 10 described above will be described with reference to FIGS. 11 and 12.

As shown in FIG. 11, in the electric power steering apparatus according to the fifth modification, the angle sensor abnormality detecting means 73 for detecting the abnormality of each of the angle sensors 15 and 16 and the angular velocity (dθ _S / dt) is estimated, and a vehicle speed sensor 77 for detecting or estimating the vehicle speed V is detected. The angle sensor abnormality detection means 73 detects an abnormality in one of the angle sensors 15 and 16. The steering angle θ detected by the normal angle sensor, the angular velocity (dθ _S / dt) of the steering wheel 11 estimated by the steering angular velocity estimation means 75, the vehicle speed V detected or estimated by the vehicle speed sensor 77, The assist torque command means 71 calculates an assist current command I _A ^{* based} on the above. This point is different from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU of the fifth modified example. FIG. 11 shows an example in which an abnormality occurs in the angle sensor 16.

  Compared with the electrical configuration of the electric power steering apparatus according to the third modified example 4 described above, the vehicle speed sensor 55 (see FIG. 7) according to the third modified example and the steering angular velocity estimating means 65 (see FIG. 7) according to the fourth modified example. It can be seen that the embodiment including both of FIG. 9 is the fifth modified example. In other words, the vehicle speed sensor 55 according to the third modification corresponds to the vehicle speed sensor 77 according to the fifth modification, and the steering angular speed estimation means 65 according to the fourth modification corresponds to the steering angular speed estimation means 75 according to the fifth modification. Correspond.

  Therefore, in the fifth modified example, the difference in configuration due to the combination of the fourth and fourth modified examples will be described with emphasis and overlapping since it is substantially the same as the fourth and fourth modified examples. About the point, those description is abbreviate | omitted. Moreover, since the mechanical configuration of the electric power steering apparatus according to the fifth modification is the same as that of the electric power steering apparatus 10 described above, the description thereof is omitted, and FIG. This is explained with the aid of it.

  As shown in FIG. 11, the electric power steering apparatus of the fifth modified example includes an angle sensor abnormality detection means 73, a steering angular speed estimation means 75, and a vehicle speed sensor 77. The angle sensor abnormality detection means 73 is similar to the angle sensor abnormality detection means 43 and 53 described in the third and third modifications, and is configured to send an abnormality detection signal to the assist torque determination means 71. The detection timing and the like are the same as those of the angle sensor abnormality detection means 43 and 53 described in the third and third modifications.

The steering angular speed estimating means 75 can estimate the steering angular speed (dθ _S / dt) of the steering wheel 11 and, similar to the steering angular speed estimating means 65 described in the third modified example, the estimated signal is used as the assist torque determining means 71. It is comprised so that it can send out to. The estimation timing and the like are the same as those in the steering angular velocity estimation means 65 described in the third modification.

  Similarly to the vehicle speed sensor 55 described in the third modification, the vehicle speed sensor 77 can detect or estimate the vehicle speed V, and is configured to send a detection signal or an estimated signal to the assist torque determining means 71. . The estimation timing and the like are the same as those of the vehicle speed sensor 55 described in the second modification.

As shown in FIG. 12, the assist torque determination means 71 includes a phase compensator 71a (71c), an assist current calculator 71b (71d), a steering angular speed correction gain calculator 71e, a vehicle speed correction gain calculator 71f, and a multiplier 71g. It is composed of Among them, the phase compensation unit 71a (71c) and the assist current calculation unit 71b (71d) are the phase compensation units 51a, 51c, 61a, 61c and the assist current calculation units 51b, 51d, 61b described in the third modification example 4, Similarly to 61d, for each steering angle θ ₁ , θ ₂ , the assist current command I _A0 ^* can be calculated based on one steering angle input from the normal angle sensor of the angle sensors 15, 16. Is provided.

Similarly to the steering angular velocity correction gain calculating unit 61e described in the fourth modified example, the steering angular velocity correction gain calculating unit 71e has a predetermined value corresponding to the steering angular velocity (dθ _S / dt) estimated by the steering angular velocity estimating unit 75. steering angular velocity correction gain G _S map or a predetermined arithmetic processing and the like capable of outputting a having the characteristics of the preset steering angular velocity correction gain G _S outputted from the steering angular velocity correction gain calculation unit 71e is inputted to the multiplier 71g Is done.

Further, the vehicle speed correction gain calculation unit 71f, like the vehicle speed correction gain calculation unit 51e described in the third modification, has a vehicle speed correction gain G having a predetermined characteristic corresponding to the vehicle speed V detected or estimated by the vehicle speed sensor 77. map and a predetermined calculation processing for can output _V is set in advance, the vehicle speed correction gain G _V outputted from the vehicle speed correction gain calculation unit 71f is also input to the multiplier 71 g.

That is, the multiplier 71 g, an assist current command _{I A0} ^* output from the assist current calculation unit 71b (71d), and the steering angular velocity correction gain _{G S} outputted from the steering angular velocity correction gain calculation unit 71e, a vehicle speed correction gain a vehicle speed correction gain G _V output from the calculation unit 71f, since three kinds of information is input, and outputs them as the multiplication process to assist current command I _a ^*. That is, the assist torque determining means 71 outputs an assist current command I _A ^* based on the steering angular speed and the vehicle speed.

Thus, for example, as shown in FIG. 11, when the abnormality of the angle sensor 16 is detected by the angle sensor abnormality detecting means 73 (the cross mark of the angle sensor 16 shown in FIG. 11), the steering from the normal angle sensor 15 is performed. Since the angle θ ₁ is input, the assist current command I _A0 ^* is calculated by a map, a predetermined calculation process, or the like by the phase compensation unit 71a and the assist current calculation unit 71b, and the steering angular velocity correction is performed on the assist current command I _A0 ^*. The assist current command I is obtained by multiplying the steering angular speed correction gain G _S corresponding to the steering angular speed (dθ _S / dt) by the gain calculation unit 71e and the vehicle speed correction gain G _V corresponding to the vehicle speed V by the vehicle speed correction gain calculation unit 71f. _A ^* is output. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 71a (71c), T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

Map other hand, when an abnormality of the angle sensor 15 is detected by the angle sensor abnormality detecting means 73, since the steering angle theta ₂ is inputted from the normal angle sensor 16, the phase compensation unit 71c and the assist current calculation unit 71d The assist current command I _A0 ^* is calculated by a predetermined calculation process or the like, and the steering angular velocity correction gain G corresponding to the steering angular velocity (dθ _S / dt) by the steering angular velocity correction gain calculation unit 71e is calculated based on the assist current command I _A0 ^*. _The assist current command I _A ^* is output by multiplying _S by the vehicle speed correction gain G _V corresponding to the vehicle speed V by the vehicle speed correction gain calculator 71f.

Note that the map used in the assist current calculation unit 71b (71d), predetermined calculation processing, and the like determine the assist current command I _A0 ^* from _one normal steering angle θ ₁ (θ ₂ ). For this reason, the accuracy of the calculated assist current command I _A ^* may be lower than that by the assist current calculation unit 31b described above, but temporarily until the other angle sensor that has failed is recovered. An assist force by the motor M can be generated by obtaining the assist current command I _A ^* .

As described above, in the electric power steering apparatus according to the fifth modification, when the angle sensor abnormality detection unit 73 detects an abnormality in one of the angle sensor 15 and the angle sensor 16, the assist torque determination unit 71 is normal. The steering angle θ ₁ (θ ₂ ) detected by the other, the vehicle speed V detected or estimated by the vehicle speed sensor 77, and the steering angular velocity (dθ _S / dt) of the steering wheel 11 estimated by the steering angular velocity estimation means 75. Based on the above, the assist force generated by the motor M is determined (see FIGS. 1 and 11). Thus, even if an abnormality occurs in one of the angle sensor 15 and the angle sensor 16, in addition to the steering angle θ ₁ (θ ₂ ) detected by the normal other, the vehicle speed V and the steering angular velocity (dθ _S / dt) Since the assist force generated by the motor M is determined based on the above, assist control corresponding to the angular velocity (dθ _S / dt) of the steering wheel 11 can be performed. Therefore, even if an abnormality occurs in one angle detection means, there is an effect that more appropriate assist control can be performed.

[Sixth modification]
Next, an electric power steering apparatus according to a sixth modification example (hereinafter referred to as “sixth modification example”) of the electric power steering apparatus 10 will be described with reference to FIGS. 13 and 14.

As shown in FIG. 13, in the electric power steering apparatus according to the sixth modified example, either one of the angle sensors 15 and 16 is detected by the angle sensor abnormality detection means 83 that detects the abnormality of each of the angle sensors 15 and 16. When the abnormality is detected, the assist torque determination means 81 calculates not only the assist current command I _A1 ^* based on the steering angle θ detected by the normal angle sensor, but also the output limit gain calculator 85 and the multiplier 87. As a result, the assist force generated by the motor M is gradually reduced over time. This point is different from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU of the sixth modified example. Accordingly, the mechanical configuration of the electric power steering apparatus according to the sixth modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This will be explained with assistance. FIG. 13 shows an example in which an abnormality occurs in the angle sensor 16.

As shown in FIG. 13, the electric power steering apparatus of the sixth modified example includes an angle sensor abnormality detection means 83 and an output limit gain calculation unit 85.
Similar to the angle sensor abnormality detection means 43 described in the second modification, the angle sensor abnormality detection means 83 detects an abnormality of the angle sensors 15 and 16, and outputs a detection signal to the assist torque determination means 81 and the output limit gain calculation. It is configured to be able to send to the unit 85. The abnormality detection of the angle sensors 15 and 16 is performed by, for example, timer interruption processing performed at predetermined intervals, and the values of the rotation angles (steering angles θ ₁ and θ ₂ ) output from the angle sensors 15 and 16 are constant. This is carried out by monitoring whether it is within a range (for example, 0 ° or more and 20 ° or less). If it is not within the predetermined range, it is determined that an abnormality has occurred in the angle sensor.

When the angle sensor abnormality detection means 83 detects an abnormality in one of the angle sensors 15 and 16, the output limit gain calculation unit 85 decreases the value of the output limit gain output to the multiplication unit 87 with the passage of time. Configured to get. That is, when an abnormality detection signal is input from the angle sensor abnormality detection means 83, for example, after a predetermined time t has elapsed from the input time (when a failure occurs), the value “1” is set until then. output limiter gain G _T gradually decreasing is configured to output to the multiplication unit 87 _{(1 ≧ G T ≧ 0)} .

Multiplying unit 87, an assist current command I _A1 ^* output from the assist torque determining means 81, and outputs to the current control unit 23 by multiplying process and an output limit gain G _T output from the output limiting gain calculator 85 Configured to get. Thus, the output limit to the gain output limit is output from the operation unit 85 a gain G values assist current command outputted from the assist torque determining means 81 by controlling the _T I _A1 ^*, the assist current command output control I _A ^* can be output.

As shown in FIG. 14, the assist torque determining means 81 is composed of a phase compensator 81a (81c) and an assist current calculator 81b (81d), similar to the assist torque determining means 41 described in the second modification. Are provided for each of the steering angles θ ₁ and θ ₂ input from the angle sensors 15 and 16. That is, the phase for each steering angle θ ₁ , θ ₂ so that the assist current command I _A1 ^* can be calculated based on one steering angle input from the normal angle sensor of the angle sensors 15, 16. Compensators 81a and 81c and assist current calculators 81b and 81d are configured.

Thus, for example, as shown in FIG. 13, when the abnormality of the angle sensor 16 is detected by the angle sensor abnormality detection means 83 (a cross mark of the angle sensor 16 shown in FIG. 13), the assist torque determination means 81 and the output An abnormality detection signal is input to the limit gain calculation unit 85. Therefore, the assist torque determining means 81, since the steering angle theta ₁ is inputted from the normal angle sensor 15, after phase compensation for the steering angle theta ₁ by the phase compensator 81a, a steering angle theta ₁ which is phase-compensated Based on ', the assist current calculation unit 81b calculates an assist current command I _A1 ^* by a map, a predetermined calculation process, and the like, and outputs it to the multiplication unit 87. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 81a (81c), T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

Further, when an abnormality detection signal is input from the angle sensor abnormality detection means 83, the output restriction gain calculation unit 85 _counts the value of the output restriction gain GT output to the multiplication unit 87 from the time of occurrence of the failure. A process of gradually decreasing from the predetermined elapsed time t is performed. As a result, the assist current command I _A ^* output from the multiplier 87 to the current control means 23 is subjected to output control that is gradually reduced after the predetermined time t has elapsed.

On the other hand, when an abnormality of the angle sensor 15 is detected by the angle sensor abnormality detecting means 83, since the steering angle theta ₂ is inputted from the normal angle sensor 16, the phase compensation for the steering angle theta ₂ by the phase compensating unit 81c After that, the assist current calculation unit 81d calculates an assist current command I _A1 ^* by a map, a predetermined calculation process or the like based on the phase-compensated steering angle θ ₂ ′ and outputs it to the multiplication unit 87. as in the case where abnormality of the angle sensor 16 is detected, the output limit gain G _T output by the output limit gain calculation unit 85 decreases gradually assist current that is output from the multiplier 87 to the current control means 23 The command I _A ^* is gradually narrowed after the predetermined time t has elapsed.

Note that the map used in the assist current calculation unit 81b (81d), predetermined calculation processing, and the like determine the assist current command I _A0 ^* from _one normal steering angle θ ₁ (θ ₂ ). Therefore, the accuracy of the calculated assist current command I _A1 ^* may be lower than that by the assist current calculation unit 31b described above. However, until the other failed angle sensor recovers, An assist force by the motor M can be generated by obtaining an assist current command I _A1 ^* .

As described above, in the electric power steering apparatus according to the sixth modified example, when an abnormality is detected in one of the angle sensor 15 and the angle sensor 16 by the angle sensor abnormality detection unit 83, the assist torque determination unit 81 determines the abnormality. In addition, the assist force generated by the motor M based on the steering angle θ ₁ (θ ₂ ) detected by the other normal is gradually reduced with the passage of time by the output limit gain calculator 85 and the multiplier 87 ( (Refer FIG. 1, FIG. 13). Thereby, even if an abnormality occurs in one of the angle sensor 15 and the angle sensor 16, the assist force can be determined based on the steering angle θ ₁ (θ ₂ ) detected by the other normal sensor, and the time Since the assist force is gradually reduced as time elapses, it is possible to notify the driver of the occurrence of a failure or the like through a steering feeling that gradually increases. Therefore, even if an abnormality occurs in the angle sensors 15 and 16, there is an effect that the driver can be notified of the abnormality of the angle sensor while performing appropriate assist control.

[Seventh modification]
Next, an electric power steering apparatus according to a seventh modification example (hereinafter referred to as “seventh modification example”) of the electric power steering apparatus 10 will be described with reference to FIGS. 15 and 16.

As shown in FIG. 15, in the electric power steering apparatus according to the seventh modified example, either one of the angle sensors 15 and 16 is detected by the angle sensor abnormality detection means 93 that detects the abnormality of each of the angle sensors 15 and 16. When an abnormality is detected, the assist torque determination means 91 calculates not only the assist current command I _A1 ^* based on the steering angle θ detected by the normal angle sensor, but also the output current maximum value limit calculation unit 97 and the output. The maximum value of the assist force generated by the motor M is gradually reduced by the current maximum value limiting means 95 with the passage of time. This point is different from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU of the seventh modified example. Therefore, the mechanical configuration of the electric power steering apparatus according to the seventh modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This is explained with the aid of it. FIG. 15 shows an example in which an abnormality occurs in the angle sensor 16.

As shown in FIG. 15, the electric power steering apparatus of the seventh modified example includes an angle sensor abnormality detection means 93, an output current maximum value restriction means 95, and an output current maximum value restriction calculation unit 97.
Similarly to the angle sensor abnormality detection means 43 described in the second modification, the angle sensor abnormality detection means 93 detects an abnormality of the angle sensors 15 and 16 and outputs a detection signal to the assist torque determination means 81 and the output current maximum value. It is configured so that it can be sent to the limit calculation unit 97. The abnormality detection of the angle sensors 15 and 16 is performed by, for example, timer interruption processing performed at predetermined intervals, and the values of the rotation angles (steering angles θ ₁ and θ ₂ ) output from the angle sensors 15 and 16 are constant. This is carried out by monitoring whether it is within a range (for example, 0 ° or more and 20 ° or less). If it is not within the predetermined range, it is determined that an abnormality has occurred in the angle sensor.

The output current maximum value limit calculation unit 97 outputs the output current maximum value I _max output to the output current maximum value limit means 95 when the angle sensor abnormality detection means 93 detects an abnormality in one of the angle sensors 15 and 16. It is comprised so that can be decreased with progress of time. That is, when an abnormality detection signal is input from the angle sensor abnormality detection means 93, for example, after a predetermined time t has elapsed from the input time (when a failure occurs), the value “1” is set until then. The output current maximum value I _max is gradually decreased and output to the output current maximum value limiting means 95 (1 ≧ I _max ≧ 0).

The output current maximum value limiting means 95 outputs so that the assist current command I _A1 ^* output from the assist torque determining means 91 does not exceed the output current maximum value I _max output from the output current maximum value limit calculating unit 97. It is configured to be limited. Thus, by controlling the output current maximum value I _max output from the output current maximum value limit calculation unit 97, output control can be performed on the assist current command I _A1 ^* output from the assist torque determining means 91. It becomes possible.

As shown in FIG. 16, the assist torque determination means 91 is composed of a phase compensation section 91a (91c) and an assist current calculation section 91b (91d), similarly to the assist torque determination means 41 described in the second modification. Are provided for each of the steering angles θ ₁ and θ ₂ input from the angle sensors 15 and 16. That is, the phase for each steering angle θ ₁ , θ ₂ so that the assist current command I _A1 ^* can be calculated based on one steering angle input from the normal angle sensor of the angle sensors 15, 16. Compensators 91a and 91c and assist current calculators 91b and 91d are configured.

Thus, for example, as shown in FIG. 15, when the abnormality of the angle sensor 16 is detected by the angle sensor abnormality detection means 93 (the cross mark of the angle sensor 16 shown in FIG. 15), the assist torque determination means 91 and the output An abnormality detection signal is input to the maximum current value limit calculation unit 97. Therefore, the assist torque determining means 91, since the steering angle theta ₁ is inputted from the normal angle sensor 15, after phase compensation for the steering angle theta ₁ by the phase compensator 91a, a steering angle theta ₁ which is phase-compensated Based on ', the assist current calculation unit 91b calculates an assist current command I _A1 ^* by a map, a predetermined calculation process, etc., and outputs it to the output current maximum value limiting means 95. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 91a (91c), T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

In addition, when the abnormality detection signal is input from the angle sensor abnormality detection unit 93, the output current maximum value limitation calculation unit 97 uses the output current maximum value I _max output to the output current maximum value limitation unit 95 to generate a failure. A process of counting from the time and gradually decreasing from the predetermined elapsed time t is performed. As a result, the maximum output current value I _max , that is, the upper limit value in the bipolar direction of the assist current command I _A ^* output to the current control means 23 is controlled to be gradually reduced after the predetermined time t has elapsed. The assist force given when the steering wheel 11 is cut deeply to the left and right is limited.

On the other hand, when an abnormality of the angle sensor 15 is detected by the angle sensor abnormality detecting means 93, since the steering angle theta ₂ is inputted from the normal angle sensor 16, the phase compensation for the steering angle theta ₂ by the phase compensating unit 91c After that, the assist current calculation unit 91d calculates an assist current command I _A1 ^* based on the phase compensated steering angle θ ₂ ′ by a map, a predetermined calculation process, etc., and outputs it to the output current maximum value limiting means 95. However, in this case as well, the output current maximum value I _max output by the output current maximum value limit calculation unit 97 is gradually reduced after the predetermined time t has passed, as in the case where the abnormality of the angle sensor 16 is detected. Therefore, the assist force given when the steering wheel 11 is cut deeply to the left and right is limited.

Note that the map used in the assist current calculation unit 91b (91d), predetermined calculation processing, and the like determine the assist current command I _A0 ^* from _one normal steering angle θ ₁ (θ ₂ ). For this reason, the accuracy of the calculated assist current command I _A ^* may be lower than that by the assist current calculation unit 31b described above, but temporarily until the other angle sensor that has failed is recovered. An assist force by the motor M can be generated by obtaining the assist current command I _A ^* .

As described above, in the electric power steering apparatus according to the seventh modified example, when an abnormality is detected in one of the angle sensor 15 and the angle sensor 16 by the angle sensor abnormality detection unit 93, the assist torque determination unit 91 determines the abnormality. Further, the maximum value of the assist force generated by the motor M based on the steering angle θ ₁ (θ ₂ ) detected by the other normal is output by the output current maximum value limiting means 95 and the output current maximum value limit calculating unit 97. It gradually decreases with time (see FIGS. 1 and 15). Thereby, even if an abnormality occurs in one of the angle sensor 15 and the angle sensor 16, the assist force can be determined based on the steering angle θ ₁ (θ ₂ ) detected by the other normal sensor, and the time Since the maximum value of the assist force is gradually decreased as the time elapses, it is possible to notify the driver of the occurrence of a failure or the like through a steering feeling that suddenly becomes heavy when the left and right deep cuts. Therefore, even if an abnormality occurs in the angle sensors 15 and 16, there is an effect that the driver can be notified of the abnormality of the angle sensor while performing appropriate assist control.

[Eighth Modification]
Next, an electric power steering apparatus according to an eighth modification example (hereinafter referred to as “eighth modification example”) of the electric power steering apparatus 10 will be described with reference to FIG.

  The electric power steering apparatus according to the eighth modified example is that the characteristic of the output current maximum value limit calculating unit 97 constituting the electric power steering apparatus according to the seventh modified example is changed. It is different from the one. Therefore, since other components have substantially the same configuration as that of the electric power steering apparatus of the seventh modified example, description thereof will be omitted, and description will be given with reference to FIG. 1 as necessary.

The electric power steering apparatus according to the eighth modification always sets the output current maximum value I _max output by the output current maximum value limit calculation unit 97 to zero (I _max = 0) regardless of the elapsed time t. . With this configuration, when an abnormality is detected in one of the angle sensor 15 and the angle sensor 16 by the angle sensor abnormality detection unit 93, the abnormality is detected by the normal other determined by the assist torque determination unit 91. The maximum value of the assist force generated by the motor M based on the steering angle θ ₁ (θ ₂ ) is made zero regardless of the passage of time by the output current maximum value limiting means 95 and the output current maximum value limiting calculation unit 97. Decrease (see FIG. 1). That is, when the angle sensor abnormality detecting means 93 detects an abnormality in one of the angle sensor 15 and the angle sensor 16, the generation of the assist force by the motor M is immediately stopped. Thereby, since the assist control by the motor M is cancelled | released, generation | occurrence | production of unscheduled assist control can be prevented. Therefore, even if an abnormality occurs in one angle detection means, there is an effect that appropriate assist control can be performed.

[Ninth modification]
Next, an electric power steering apparatus according to a ninth modification example (hereinafter referred to as “ninth modification example”) of the electric power steering apparatus 10 will be described with reference to FIGS. 17 and 18.

As shown in FIG. 17, in the electric power steering apparatus of the ninth modified example, the deviation (θ ₁ −θ ₂₎ between the steering angle θ ₁ detected by the angle sensor 15 and the steering angle θ ₂ detected by the angle sensor 16. ) obtained by calculation means 113 a twist angle [Delta] [theta] _H of the torsion bar 14 is also detected or estimated vehicle speed V by the vehicle speed sensor 115, the assist current by the assist torque determining means 111 on the basis of the torsion angle [Delta] [theta] _H and the vehicle speed V Command I _A ^* is calculated. This point is different from the electrical configuration of the first CU 20 in the electrical configuration of the ECU of the ninth modified example.

That is, the electric power steering apparatus according to the ninth modification adds the vehicle speed sensor 115 to the configuration of the electric power steering apparatus according to the first modification described with reference to FIG. Based on the above, the assist torque determining means 111 calculates the assist current command I _A ^* . Therefore, the mechanical configuration of the electric power steering apparatus according to the ninth modified example is the same as that of the electric power steering apparatus 10 described above, and therefore the description thereof is omitted, and FIG. This is explained with the aid of it.

  As shown in FIG. 17, the vehicle speed sensor 115 can detect or estimate the vehicle speed V, and is configured to send a detection signal or an estimated signal to the assist torque determining means 111. The detection or estimation of the vehicle speed V is executed by, for example, timer interruption processing performed at predetermined intervals.

As shown in FIG. 18, in the ninth modification, the assist torque determination unit 111 is configured by a phase compensation unit 111a, an assist current calculation unit 111b, a vehicle speed correction gain calculation unit 111c, and a multiplication unit 111d. Thereby, the deviation between the steering angle theta ₂ of the steering angle theta ₁ and the pinion shaft 13 of the steering shaft 12 (θ ₁ -θ _2), i.e. twist angles [Delta] [theta] _H of the torsion bar 14 is inputted to the assist torque determining means 111 If, after phase compensation with helix angle [Delta] [theta] _H of the torsion bar 14 by the phase compensation section 111a, a phase-compensated assist current by the assist current calculation unit 111b based on the twist angle [Delta] [theta] _{H 'at} the map or a predetermined arithmetic processing and the like Command I _A0 ^* is calculated. Here, in ((1 + T ₂ · S) / (1 + T ₁ · S)) of the phase compensation unit 111a, T ₁ and T ₂ indicate filter constants, and S indicates a differential operator.

On the other hand, the vehicle speed correction gain calculation unit 111c has a predetermined characteristic corresponding to the vehicle speed V detected or estimated by the vehicle speed sensor 115, for example, a characteristic that the vehicle speed correction gain G _V decreases with an increase in the vehicle speed V above a certain level ( 0 ≦ G _V ≦ 1) vehicle speed correction gain G _V output to be mapped or a predetermined arithmetic processing or the like having a are set in advance. Then, the vehicle speed correction gain G _V output from the vehicle speed correction gain calculation unit 111c is multiplied by the assist current command I _A0 ^* output from the assist current calculation unit 111b via the multiplier 111d, and the assist current command I _A ^* Is output. That is, the assist current command I _A ^* based on the vehicle speed is output.

As described above, in the electric power steering apparatus according to the ninth modified example, the assist torque determination unit 111 uses the vehicle speed sensor 115 in addition to at least one of the steering angle θ ₁ of the steering shaft 12 and the steering angle θ ₂ of the pinion shaft 13. Based on the detected or estimated vehicle speed V, the assist force generated by the motor M is determined. As a result, it is possible to perform assist control corresponding to the vehicle speed V. For example, the assist force is set to be larger than that during medium speed traveling when the vehicle is stopped or traveling at low speed, and the assist force is greater than during medium speed traveling during high speed traveling. Can be set small. Therefore, in addition to the effect of performing the assist control based on the steering angle, there is an effect of performing the assist control according to the vehicle speed V.

[First Embodiment]
Next, an electric power steering apparatus according to a first embodiment of the present invention will be described with reference to FIGS .

  As shown in FIG. 19, in the electric power steering apparatus according to the first embodiment, the rotation angle of the motor M is detected in addition to the angle sensor abnormality detection means 123 that detects the abnormality of each of the angle sensors 15 and 16. Alternatively, the motor rotation angle sensor 19 to be estimated and the steering angle estimation means 127 for estimating the rotation angle of the steering shaft 12 based on the motor rotation angle detected or estimated by the motor rotation angle sensor 19 are detected by the angle sensor 15. The rotation angle of the steering shaft 12 (hereinafter referred to as “steering detection angle” in the first embodiment) and the rotation angle of the steering shaft 12 estimated by the steering angle estimation means 127 (hereinafter referred to as “steering” in the first embodiment). When the deviation from the “estimated angle” is equal to or greater than a predetermined value, it is detected that an abnormality has occurred in angle sensor That. This point differs from the above-described electrical configuration of the ECU 20 in the electrical configuration of the ECU according to the first embodiment.

  Further, as compared with the electrical configuration of the electric power steering apparatus of the second modified example described above, the motor rotation angle sensor 19 and the steering angle estimation means 127 are provided, which are detected or estimated by the motor rotation angle sensor 19. The difference is that the estimated steering angle is estimated by the steering angle estimation means 127 based on the motor rotation angle and is input to the angle sensor abnormality detection means 123. Therefore, since the mechanical configuration of the electric power steering apparatus according to the first embodiment is the same as that of the electric power steering apparatus 10 described above, the description thereof will be omitted, and FIG. This is explained with the aid of it. The assist torque determining means 121 has substantially the same configuration as the assist torque determining means 41 shown in FIGS. 5 and 6 and will not be described.

  As shown in FIG. 19, the electric power steering apparatus according to the first embodiment includes a motor rotation angle sensor 19, an angle sensor abnormality detection unit 123, and a steering angle estimation unit 127. As already described with reference to FIG. 1, the motor rotation angle sensor 19 can detect the rotation angle of the motor M. For example, an absolute angle sensor such as an absolute encoder or a resolver, or a relative angle sensor such as an incremental encoder. Is used.

  In addition to the case where the rotation angle of the motor M is detected by the motor rotation angle sensor 19, the rotation angle of the motor M may be estimated by, for example, voltage equations shown in the following equations (1) and (2).

  Here, in Expression (1), ω is an angular velocity (rad / sec) of the motor M, V is an applied voltage (V) to the motor M, R is an internal resistance (Ω) of the motor M, and L is an inductance ( H) and I are motor currents (A) flowing through the motor M, and Ke is a counter electromotive force constant by the motor M. In equation (2), θ represents the rotation angle of the motor M, and is the time integral of the angular velocity ω of the motor M.

  Thereby, even if it is a case where the motor rotation angle sensor 19 is not provided, since the rotation angle of the motor M can be estimated and calculated | required, it leads to reduction of a number of parts and can contribute to reduction of cost.

  The angle sensor abnormality detection means 123 can detect abnormality of the angle sensors 15 and 16 by the abnormality detection process of the angle sensor shown in FIG. The abnormality detection process of the angle sensor is performed by an interrupt process that occurs at intervals of 5 milliseconds, for example. Although FIG. 20 shows the flow of the abnormality detection process for the angle sensor 15, the flow of the abnormality detection process for the angle sensor 16 is also processed in the same manner as shown in FIG. Therefore, hereinafter, the flow of the abnormality detection process of the angle sensor 15 will be described with reference to FIG. 20, but it should be noted that the abnormality detection process of the angle sensor 16 is performed in the same manner.

As shown in FIG. 20, in the abnormality detection process of the angle sensor 15, first, in step S101, the steering angle θ ₁ (n) is captured by the angle sensor 15. Next, in step S103, a steering angle estimation process, which is a subroutine, is performed to obtain the steering angle θ _S (n). Details of the steering angle estimation process will be described later (see FIG. 21). Note that n in parentheses attached after θ ₁ , θ _S, etc. is a subscript indicating the steering angle detected or estimated at the n-th time (hereinafter, this embodiment and other embodiments). Same in form).

In the following step S105, a deviation (absolute value) between the steering angle θ _S (n) acquired by the steering angle estimation process (S103) and the steering angle θ ₁ (n) detected by the angle sensor 15 is obtained, and the deviation is predetermined. A process of determining whether or not the value is greater than or equal to ₀ is performed. If the deviation is equal to or greater than the predetermined value θ ₀ (Yes in S105), there is a possibility that an abnormality has occurred in the angle sensor 15, and therefore the process proceeds to step S107 to count up the abnormality timer tc (tc = Tc + 1). On the other hand, if the deviation is not equal to or greater than the predetermined value θ ₀ (No in S105), there is a possibility that the angle sensor 15 is normal. Therefore, the process proceeds to step S109 and the abnormality timer tc clear process (tc = 0). )I do.

  When the processing in step S107 or step S109 is completed, whether or not a predetermined time T (for example, 300 milliseconds to 600 milliseconds) has elapsed since the abnormality timer tc continues to be counted up without being cleared halfway in step S111. It is determined whether or not the value of the abnormality timer tc has reached a predetermined value or more. As a result of this determination, if the abnormality timer tc is counted up for a predetermined time T (Yes in S111), it can be determined that an abnormality has occurred in the angle sensor 15. Therefore, the abnormality of the angle sensor 15 is determined in step S113. A process for notifying the driver of the occurrence is performed.

  On the other hand, if it is determined in step S113 that the abnormality timer tc has not been counted up for a predetermined time T (No in S111), since it can be determined that no abnormality has occurred in the angle sensor 15, the step is again performed. The process shifts to S101 and the above-described series of abnormality detection processing of the angle sensor 15 is performed.

  Also, the processes in steps S107, S109, and S111 are deleted, and step S113 is placed immediately after the Yes determination process in step S105. If the determination in step S105 is No, the process proceeds to step S101. You may change the flow of the said abnormality detection process so that it may transfer. Thus, since the abnormality occurrence notification of the angle sensor 15 (angle sensor 16) can be immediately performed in step S113 without waiting for the elapse of a predetermined time, it is possible to expect an increase in the abnormality detection process.

Here, the flow of the steering angle estimation process by the subroutine of step S103 will be described with reference to FIG.
As shown in FIG. 21, in the steering angle estimation process, first, in step S151, it is determined whether or not this process is the first time. When this processing is the first time (Yes in step S151), the steering angle θ _S (n−1) calculated last time is not stored, so that the initial value θ of the steering angle is obtained in steps S153, S155, S157, and S159. Processing for calculating _S (1) is performed.

That is, in step S153, the steering angle θ ₁ (1) is captured by the angle sensor 15, in the subsequent step S155, the steering angle θ ₂ (1) is captured by the angle sensor 16, and in step S157, the motor rotation angle sensor 19 is captured. Processing for taking in the rotation angle θ _M (1) of the motor M is sequentially performed.

Then, the current steering angle is calculated as an average value of the steering angle θ ₁ (1) at step S153 and the steering angle θ ₂ (1) at step S155, and this is stored as the initial value θ _S (1) of the steering angle. To do. The steering angle θ _S (1) is θ _S (1) = (θ ₁ (1) + θ ₂ (1)) / 2.

On the other hand, if this processing has already been performed (No in step S151), since the steering angle θ _S (n−1) calculated last time is stored, the process proceeds to step S161, and θ _S (n). _{= θ S (n-1)} + (θ M (n) -θ M (n-1)) / G by calculating the steering estimated angle θ _{S (n).} Here, θ _M (n) represents the current motor rotation angle, θ _M (n−1) represents the previous motor rotation angle, and G represents the reduction ratio by the reducer 17 shown in FIG. The steering angle calculation process in step S161 is performed by the steering angle estimation unit 127.
When such a series of steps S151 to S161 is completed, the process returns to the above-described abnormality detection process of the angle sensor 15, and the process proceeds to step S105.

As described above, according to the electric power steering ToSo location of the first embodiment, relatively rotatably connected by a torsion bar 14 and the steering shaft 12 and the pinion shaft 13, the angle of rotation angle of the steering shaft 12 The rotation angle of the pinion shaft 13 is detected by the sensor 15 and the angle sensor 16 respectively. Then, the assist torque determining means 121 determines the assist force generated by the motor M based on at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13, and the angle sensor 15 (or angle sensor 16). The deviation between the steering detection angle θ ₁ (n) (or θ ₂ (n)) detected by the steering angle estimation means 127 and the estimated steering angle θ _S (n) estimated by the steering angle estimation unit 127 is equal to or greater than a predetermined value θ ₀ . At this time, the angle sensor abnormality detection means 123 detects that an abnormality has occurred in the angle sensor 15 (or the angle sensor 16).

Accordingly, the rotation angle of the steering shaft 12 can be detected, and the torsion amount of the torsion bar 14 can be detected as the torsion angle from at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13. Therefore, the assist control can be performed in consideration of the steering angle of the steering wheel 11. Therefore, there is an effect that assist control based on the steering angle can be performed. Also, the deviation | θ ₁ (n) −θ _S (n) | (or | θ ₂ (n) between the steering detection angle θ ₁ (n) (or θ ₂ (n)) and the estimated steering angle θ _S (n) ) −θ _S (n) |), it can be detected that an abnormality has occurred in the angle sensor 15 (or the angle sensor 16). Therefore, there is an effect that an abnormality in the angle sensor 15 (or the angle sensor 16) can be detected. is there.

Further, according to the electric power steering ToSo location of the first embodiment, relatively rotatably connected by a torsion bar 14 and the steering shaft 12 and the pinion shaft 13, the angle sensor 15 the rotation angle of the steering shaft 12, Further, the rotation angle of the pinion shaft 13 is detected by the angle sensor 16. Then, the assist torque determining means 121 determines the assist force generated by the motor M based on at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13, and the angle sensor 15 (or angle sensor 16). | Θ ₁ (n) − between the steering detection angle θ ₁ (n) (or θ ₂ (n)) detected by the steering angle estimation means 127 and the estimated steering angle θ _S (n) estimated by the steering angle estimation unit 127. When the state where θ _S (n) | (or | θ ₂ (n) −θ _S (n) |) is equal to or greater than a predetermined value θ ₀ continues for a predetermined time T, the angle sensor 15 (or the angle sensor 16) is abnormal. Is detected by the angle sensor abnormality detection means 123.

Accordingly, the rotation angle of the steering shaft 12 can be detected, and the torsion amount of the torsion bar 14 can be detected as the torsion angle from at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13. Therefore, the assist control can be performed in consideration of the steering angle of the steering wheel 11. Therefore, there is an effect that assist control based on the steering angle can be performed. Also, the deviation | θ ₁ (n) −θ _S (n) | (or | θ ₂ (n) between the steering detection angle θ ₁ (n) (or θ ₂ (n)) and the estimated steering angle θ _S (n) ) −θ _S (n) |) is continuously detected for a predetermined time T, so that it is possible to detect an abnormality of the angle sensor 15 (or the angle sensor 16) more accurately.

[Second Embodiment]
Next, an electric power steering apparatus according to a second embodiment will be described with reference to FIGS. The electric power steering apparatus according to the second embodiment corresponds to the electric power steering apparatus according to claims 1 to 6 described in the claims.

  In the electric power steering apparatus according to the second embodiment, a change is made to the abnormality detection process by the angle sensor abnormality detection means 123 constituting the electric power steering apparatus of the first embodiment described above, and the angle sensor 15 (or The rotation angle of the steering shaft 12 detected by the angle sensor 16) (hereinafter referred to as “steering detection angle” in the second embodiment) and the rotation angle of the steering shaft 12 estimated by the steering angle estimating means 127 (hereinafter referred to as the present embodiment). In the second embodiment, an abnormality of the angle sensor 15 (or the angle sensor 16) is detected based on the ratio of the “steering estimated angle”). This point is different from that of the first embodiment. Therefore, since the other components have substantially the same configuration as that of the electric power steering apparatus of the first embodiment, the description thereof is omitted, and FIGS. 1 and 19 are used as necessary. explain.

  As shown in FIG. 22, the electric power steering apparatus according to the second embodiment performs the following abnormality detection process in the angle sensor abnormality detection means 123 (FIG. 19). The abnormality detection processing of the angle sensor is also performed by interrupt processing that occurs at intervals of 5 milliseconds, for example, as in the abnormality detection processing according to the first embodiment. Note that the flow of the abnormality detection process of the angle sensor 15 will be described below, but it should be noted that the abnormality detection process of the angle sensor 16 is performed in the same manner.

First, in step S201, the steering angle θ ₁ (n) is captured by the angle sensor 15. Next, in step S203, a steering angle estimation process, which is a subroutine, is performed to obtain the steering angle θ _S (n). Details of the steering angle estimation process will be described later (see FIG. 23).

Next, in step S205, it is determined whether or not the rotation direction of the steering detection angle θ ₁ (n) and the steering estimation angle θ _S (n) are the same direction. That is, depending on whether the rotation direction of the steering angle θ ₁ (n) and the rotation direction of the steering angle θ _S (n) are the same direction or the opposite direction, parameters (for example, steering angle ratio α, Since the abnormality of the angle sensor 15 can be detected more accurately by changing the steering deviation angle ratio β), the steering detection angle θ ₁ (n) detected by the angle sensor 15 and the steering angle estimation process are used. Based on the sign (positive or negative) obtained by multiplying the estimated steering angle θ _S (n), it is determined whether or not the rotation is in the same direction in step S207.

If it is determined in step S205 that the directions are the same (Yes in step S205), the process proceeds to step S207 to calculate the steering angle ratio α, that is, the steering detection angle θ ₁ (n) is calculated as the estimated steering angle θ _S. The ratio α of both is calculated by dividing by (n). The steering angle ratio α corresponds to the “ratio α10” described in the claims (Claim 1 or 2 ), and in the case of the angle sensor 16, the claims (Claim 3 or This corresponds to the “ratio α20” described in 4 ).

In the next step S209, the first predetermined value α1 and the second predetermined value α2 are obtained by a predetermined calculation process to be described later, and the steering detection angle θ is within the range between the first and second predetermined values α1 and α2. Whether the ratio α between ₁ (n) and the estimated steering angle θ _S (n) is within the range (α2 ≦ α ≦ α1) is determined in the subsequent step S211. If it is determined in step S211 that the ratio α is within the range (Yes in S211), the angle sensor 15 may be normal. Therefore, the process proceeds to step S215 to clear the abnormality timer tc. (Tc = 0) is performed, and the process returns to step S201 again. The first predetermined value α1 and the second predetermined value α2 correspond to the “predetermined value α11” and the “predetermined value α12” described in the claims (Claims 1, 2, 5 ), respectively. In the case of the angle sensor 16, it corresponds to “predetermined value α21” and “predetermined value α22” described in the claims (claims 3, 4, 6 ).

  On the other hand, if the ratio α is not within the range (No in S211), there is a possibility that an abnormality has occurred in the angle sensor 15. Therefore, the process proceeds to step S213 and the abnormality timer tc is counted up (tc = tc + 1). In step S217, whether or not the predetermined time T has elapsed since the abnormal timer tc has been counted up without being cleared in the middle, that is, the value of the abnormal timer tc has reached a predetermined value or more. Judgment whether or not there is. If the abnormality timer tc is counted up for a predetermined time T by this determination (Yes in S217), it can be determined that an abnormality has occurred in the angle sensor 15, and therefore the abnormality of the angle sensor 15 is determined in step S219. A process for notifying the driver of the occurrence is performed. Then, the series of abnormality detection processing ends.

If it is determined in step S205 that they are not in the same direction, that is, the rotation direction of the steering detection angle θ ₁ (n) and the estimated steering angle θ _S (n) is opposite (No in step S205), the process proceeds to step S221. processing, i.e. to sign inversion by dividing minus the steering estimated angle θ _{S (n)} from the steering detection angle θ _{1 (n)} in the steering estimated angle θ _{S (n)} which is determining the steering deviation angle ratio β and (Β = − (θ ₁ (n) −θ _S (n)) / θ _S (n)) to calculate the steering deviation angle ratio β. The steering deviation angle ratio β corresponds to the “ratio β10” described in the claims (Claims 1 and 2 ). In the case of the angle sensor 16, the claims (Claim 3 ). 4 ), which corresponds to the “ratio β20”.

Then, in step S223, the first predetermined value β1 is obtained by a predetermined calculation process to be described later, and whether or not the steering deviation angle ratio β obtained in step S221 is smaller than the first predetermined value β1 is determined in step S225. to decide. If it can be determined that the steering deviation angle ratio β is smaller than the first predetermined value β1 by the determination processing in step S225 (Yes in S225), the angle sensor 15 may be normal, and the process proceeds to step S229. , The abnormality timer tc clear process (tc = 0) is performed, and the process returns to step S201 again. The first predetermined value β1 corresponds to the “predetermined value β11” described in the claims (claims 1 , 2 , 5 ). In the case of the angle sensor 16, This corresponds to the “predetermined value β21” described in claims 3 , 4 , 6 ).

  On the other hand, if it cannot be determined that the steering deviation angle ratio β is smaller than the first predetermined value β1 (No in S225), there is a possibility that an abnormality has occurred in the angle sensor 15, and the process proceeds to step S227. The abnormal timer tc is counted up (tc = tc + 1), and further incremented without being cleared halfway by the abnormal timer tc in step S231, and then a predetermined time T (for example, 300 milliseconds to 600 milliseconds). Is determined, that is, whether or not the value of the abnormality timer tc has reached a predetermined value or more. If it is determined that the abnormality timer tc has been counted up for a predetermined time T (Yes in S231), it can be determined that an abnormality has occurred in the angle sensor 15. Therefore, the abnormality of the angle sensor 15 is determined in step S219. A process for notifying the driver of the occurrence is performed. Then, the series of abnormality detection processing ends.

Here, the flow of the steering angle estimation process by the subroutine of step S203 will be described with reference to FIG.
As shown in FIG. 23, this steering angle estimation process is performed in substantially the same manner as the steering angle estimation process according to the first embodiment described with reference to FIG. That is, steps S251, S253, S255, S257, S259, and S263 shown in FIG. 23 correspond to steps S151, S153, S155, S157, S159, and S161 shown in FIG. The steering angle estimation process according to the second embodiment is the same as the steering angle estimation process according to the first embodiment, except that the process at step S261 is added before step S263.

As shown in FIG. 23, first, in step S251, it is determined whether or not this processing is the first time. If this processing is the first time (Yes in step S251), steps S153, S155, S157, and S159 are performed. To calculate the steering angle initial value θ _S (1).

In step S253, the steering angle θ ₁ (1) is captured by the angle sensor 15, in the subsequent step S255, the steering angle θ ₂ (1) is captured by the angle sensor 16, and in step S257, the motor M is detected by the motor rotation angle sensor 19. The rotation angle θ _M (1) of is taken in. Then, the current steering angle is calculated as an average value of the steering angle θ ₁ (1) and the steering angle θ ₂ (1), and this is stored as the initial value θ _S (1) of the steering angle (θ _S (1 ) = (Θ ₁ (1) + θ ₂ (1)) / 2).

On the other hand, if this processing has already been performed (No in step S251), since the steering angle θ _S (n−1) calculated last time is stored, the process proceeds to step S261, where the motor rotation angle sensor 19 is stored. To capture the motor rotation angle θ _M (n), and further, in step S263, steering by θ _S (n) = θ _S (n−1) + (θ _M (n) −θ _M (n−1)) / G The estimated angle θ _S (n) is calculated. Here, θ _M (n) represents the current motor rotation angle, θ _M (n−1) represents the previous motor rotation angle, and G represents the reduction ratio by the reducer 17 shown in FIG. Note that the steering angle calculation processing in step S263 is performed by the steering angle estimation means 127.
When such a series of steps S251 to S263 is completed, the process returns to the above-described abnormality detection process of the angle sensor 15, and the process proceeds to step S205.

In addition, each process by step S213, S215, S217 is as described in a claim (Claims 2 and 4 ) "when the state where ratio αxx becomes is continued for a predetermined time" (xx is 10 or 20) It is equivalent to. In addition, each processing in steps S227, S229, and S231 is performed when “the ratio βxx is in a state in which the ratio βxx is equal to a predetermined time” (xx is 10 or 20) described in the claims (claims 2 and 4 ). It is equivalent.

  In addition, the processes in steps S213, S215, and S217 are deleted, and step S219 is placed immediately after the No determination process in step S211. If the determination in step S211 determines Yes, the process proceeds to step S201. You may change the flow of the said abnormality detection process so that it may transfer. Further, the processes in steps S227, S229, and S231 are deleted, and step S219 is placed immediately after the No determination process in step S225. If the determination in step S225 is Yes, the process proceeds to step S201. As such, the flow of the abnormality detection process may be changed.

  As a result, it is possible to immediately notify the occurrence of abnormality of the angle sensor 15 (angle sensor 16) in step S219 without waiting for the elapse of a predetermined time, so that the speed of the abnormality detection process can be expected.

Further, in step S205, a process of determining whether or not the rotation direction of the steering detection angle θ ₁ (n) and the steering estimation angle θ _S (n) is the same direction is performed. From the viewpoint of simplifying and increasing the speed, the processes in steps S205, S221, S223, S225, S227, S229, and S231 may be deleted.

Here, “calculation of the first and second predetermined values α1 and α2” performed in step S209 and “calculation of the first predetermined value β1” performed in step S223 will be described.
The above-described angle sensors 15 and 16 may cause a “detection error” caused by a backlash of the speed reducer 17 or a torsion angle of the torsion bar 14 that may be mechanically generated. It is known that the steering angles θ ₁ and θ ₂ have a deviation of a certain predetermined value or less. Therefore, in the second embodiment, the first predetermined value α1 and the second predetermined value α2 are calculated in step S209, and the first predetermined value β1 is calculated in step S223, thereby absorbing the influence of the deviation.

Hereinafter, a method of calculating these predetermined values α1, α2, and β1 will be described.
First, assuming that a deviation (predetermined value) caused by backlash of the speed reducer 17 is Δθ ₀ (Δθ ₀ > 0), | θ ₁ (n) −θ _S (n) | ≦ Δθ ₀ is satisfied.
Here, assuming that the deviation that can actually occur is Δθ, θ ₁ (n) = θ _S (n) + Δθ, and therefore the rotation direction between the steering detection angle θ ₁ (n) and the estimated steering angle θ _S (n) Are in the same direction, that is, θ ₁ (n) · θ _S (n)> 0, both sides of θ ₁ (n) = θ _S (n) + Δθ are divided by θ _S (n) to obtain the following equation (3 ) Is obtained. Further, if the angle sensors 15 and 16 are normal, the relationship of −Δθ ₀ ≦ Δθ ≦ Δθ ₀ is satisfied, so that the equation (3) can be transformed into the following equation (4).

  Therefore, whether or not the angle sensors 15 and 16 are normal can be determined by the determination threshold values α1 and α2 according to the following equation (5).

On the other hand, when the rotation direction of the steering detection angle θ ₁ (n) and the estimated steering angle θ _S (n) is opposite, that is, θ ₁ (n) · θ _S (n) <0, θ ₁ (n) = When both sides of θ _S (n) + Δθ are divided by θ _S (n), the following equations (6) and (7) are obtained.
Here, if the angle sensors 15 and 16 are normal, when θ _S (n) <0 (θ ₁ (n)> 0), Δθ ≦ θ ₁ (n) −θ _S (n)> 0, Δθ ≦ Since Δθ ₀ is satisfied, the expressions (6) and (7) can be transformed into the following expression (8). Similarly, the following equation (8) is obtained when θ _S (n)> 0 (θ ₁ (n) <0).

  Therefore, whether or not the angle sensors 15 and 16 are normal can be determined by the determination threshold β1 according to the following equation (9).

Since the predetermined values α1, α2, and β1 are thus calculated, these predetermined values are detected by the steering angle detected by the angle sensor 15 (or the angle sensor 16) or the steering angle estimating means 127. It changes based on the estimated angle. That is, whether the angle sensor 15 (or the angle sensor 16) is abnormal in response to a change in the steering detection angle θ ₁ (n) (or θ ₂ (n)) or the estimated steering angle θ _S (n). Can be judged. Note that Δθ ₀ described above is set to 12 ° (± 6 °), for example, in consideration of the manual stopper of the torsion bar 14.

As described above, according to the electric power steering ToSo location of the second embodiment, relative rotatably connected by a torsion bar 14 and the steering shaft 12 and the pinion shaft 13, the angle of rotation angle of the steering shaft 12 The rotation angle of the pinion shaft 13 is detected by the sensor 15 and the angle sensor 16 respectively. Then, the assist torque determining means 121 determines the assist force generated by the motor M based on at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13, and the angle sensor 15 (or angle sensor 16). Between the rotation angle θ ₁ (n) (or θ ₂ (n)) of the steering shaft 12 detected by the steering angle estimation means 127 and the estimated rotation angle θ _S (n) of the steering shaft 12 estimated by the steering angle estimation means 127. When α (α10) is not less than a predetermined value α1 (α11) and not more than a predetermined value α2 (α12), it is detected that an abnormality has occurred in the angle sensor 15 (or the angle sensor 16).

Accordingly, the rotation angle of the steering shaft 12 can be detected, and the torsion amount of the torsion bar 14 can be detected as the torsion angle from at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13. Therefore, the assist control can be performed in consideration of the steering angle of the steering wheel 11. Therefore, there is an effect that assist control based on the steering angle can be performed. Further, from the steering detection angle theta _{1 (n)} (or theta _{2 (n))} and the ratio of the steering estimated angle _{θ S (n) α (α10} ), abnormality occurs in the angle sensor 15 (or the angle sensor 16) Therefore, there is an effect that an abnormality of the angle sensor 15 (or the angle sensor 16) can be detected.

Further, according to the electric power steering ToSo location of the second embodiment, relative rotatably connected by a torsion bar 14 and the steering shaft 12 and the pinion shaft 13, the angle sensor 15 the rotation angle of the steering shaft 12, Further, the rotation angle of the pinion shaft 13 is detected by the angle sensor 16. Then, the assist torque determining means 121 determines the assist force generated by the motor M based on at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13, and the angle sensor 15 (or angle sensor 16). Between the rotation angle θ ₁ (n) (or θ ₂ (n)) of the steering shaft 12 detected by the steering angle estimation means 127 and the estimated rotation angle θ _S (n) of the steering shaft 12 estimated by the steering angle estimation means 127. When the state where α (α10) is a predetermined value α1 (α11) or more and a predetermined value α2 (α12) or less continues for a predetermined time T, it is detected that an abnormality has occurred in the angle sensor 15 (or the angle sensor 16).

Accordingly, the rotation angle of the steering shaft 12 can be detected, and the torsion amount of the torsion bar 14 can be detected as the torsion angle from at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13. Therefore, the assist control can be performed in consideration of the steering angle of the steering wheel 11. Therefore, there is an effect that assist control based on the steering angle can be performed. Further, the angle sensor 15 (or angle sensor 16) causes the ratio α (α10) between the steering detection angle θ ₁ (n) (or θ ₂ (n)) and the steering estimated angle θ _S (n) to continue for a predetermined time T. Therefore, there is an effect that the abnormality of the angle sensor 15 (or the angle sensor 16) can be detected more accurately.

Furthermore, according to the electric power steering apparatus of the second embodiment (corresponding to the electric power steering apparatus according to claim 1 or 3 ), the steering shaft 12 and the pinion shaft 13 are moved relative to each other by the torsion bar 14. The rotation angle of the steering shaft 12 is detected by the angle sensor 15, and the rotation angle of the pinion shaft 13 is detected by the angle sensor 16. Then, the assist torque determining means 121 determines the assist force generated by the motor M based on at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13, and the angle sensor 15 (or angle sensor 16). The rotation angle θ ₁ (n) () or θ ₂ (n)) of the steering shaft 12 detected by the above and the estimated rotation angle θ _S (n) of the steering shaft 12 estimated by the steering angle estimation means 127 Steering shaft detected when the ratio α (α10) of both angles is not less than a predetermined value α1 (α11) and not more than a predetermined value α2 (α12), or is detected by the angle sensor 15 (or the angle sensor 16). When the rotation angle of 12 and the estimated rotation angle θ _S (n) of the steering shaft 12 estimated by the steering angle estimation means 127 rotate in directions opposite to each other, When the ratio β1 (β10) is equal to or greater than the predetermined value β1 (β11), it is detected that an abnormality has occurred in the angle sensor 15 (or the angle sensor 16).

Accordingly, the rotation angle of the steering shaft 12 can be detected, and the torsion amount of the torsion bar 14 can be detected as the torsion angle from at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13. Therefore, the assist control can be performed in consideration of the steering angle of the steering wheel 11. Therefore, there is an effect that assist control based on the steering angle can be performed. In addition, the angle sensor 15 (or the angle sensor 16) causes the ratio α (α10, β10) between the steering detection angle θ ₁ (n) (or θ ₂ (n)) and the estimated steering angle θ _S (n) to be rotated. Since the detection is performed in comparison with the predetermined values α1 (α11), α2 (α12), and β (β11) set for each, there is also an effect that the abnormality of the angle detection means can be detected more accurately.

Furthermore, according to the electric power steering apparatus of the second embodiment (corresponding to the electric power steering apparatus according to claim 2 or 4 ), the steering shaft 12 and the pinion shaft 13 are connected by the torsion bar 14. The rotation angle of the steering shaft 12 is detected by the angle sensor 15, and the rotation angle of the pinion shaft 13 is detected by the angle sensor 16. Then, the assist torque determining means 121 determines the assist force generated by the motor M based on at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13, and the angle sensor 15 (or angle sensor 16). Is the rotation angle θ ₁ (n) (or θ ₂ (n)) of the steering shaft 12 detected by the steering angle estimation means 127 and the estimated rotation angle θ _S (n) of the steering shaft 12 estimated by the steering angle estimation means 127. When the ratio α (α10) between the two angles is the predetermined value α1 (α11) or more and the predetermined value α2 (α12) or less for a predetermined time when turning in the same direction, or the angle sensor 15 (or the angle sensor 16) And the estimated rotation angle θ _S (n) of the steering shaft 12 estimated by the steering angle estimation means 127. When the state in which the ratio β1 (β10) is equal to or greater than the predetermined value β1 (β11) continues for a predetermined time when they rotate in opposite directions, an abnormality has occurred in each angle sensor 15 (or angle sensor 16). To detect.

Accordingly, the rotation angle of the steering shaft 12 can be detected, and the torsion amount of the torsion bar 14 can be detected as the torsion angle from at least one of the rotation angle of the steering shaft 12 and the rotation angle of the pinion shaft 13. Therefore, the assist control can be performed in consideration of the steering angle of the steering wheel 11. Therefore, there is an effect that assist control based on the steering angle can be performed. In addition, the angle sensor 15 (or the angle sensor 16) causes the ratio α (α10, β10) between the steering detection angle θ ₁ (n) (or θ ₂ (n)) and the estimated steering angle θ _S (n) to be rotated. In comparison with the predetermined values α1 (α11), α2 (α12), β (β11) set for each of them, the detection is continued for a predetermined time, so that the effect of detecting the abnormality of the angle detection means more accurately is also achieved. is there.

Further, according to the electric power steering apparatus of the second embodiment (corresponding to the electric power steering apparatus according to claim 5 or 6 ), predetermined values α1 (α11, α21), α2 (α12, α22). ), Β1 (β11, β21) is the steering detection angle θ ₁ (n) (or θ ₂ (n)) detected by the angle sensor 15 (or angle sensor 16) or the steering angle estimated by the steering angle estimation means 127. since changes based on the estimated angle θ _{S (n),} dynamically in response to changes in the steering detection angle θ _{1 (n) (or} θ _{2 (n))} or the steering estimated angle θ _{S (n),} the angle Whether or not the sensor 15 (or the angle sensor 16) is abnormal can be determined. Therefore, there is an effect that the abnormality of the angle sensor 15 (or the angle sensor 16) can be detected more accurately.

It is a block diagram which shows the main structures of the electric power steering device used as the base of embodiment of this invention. FIG. 2 is a block diagram showing main electrical configurations of an ECU and a motor drive circuit shown in FIG. 1. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU of the electric power steering device which concerns on a 1st modification, and a motor drive circuit. It is a block diagram which shows the main electric structures of ECU and motor drive circuit of the electric power steering apparatus which concern on a 2nd modification. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU of the electric power steering device which concerns on a 3rd modification, and a motor drive circuit. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU of the electric power steering device which concerns on a 4th modification, and a motor drive circuit. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU and motor drive circuit of the electric power steering apparatus which concerns on a 5th modification. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU and motor drive circuit of the electric power steering apparatus which concerns on a 6th modification. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU and motor drive circuit of an electric power steering apparatus according to a seventh modification. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. It is a block diagram which shows the main electrical structures of ECU of the electric power steering device which concerns on a 9th modification, and a motor drive circuit. It is a block diagram which shows the structure of the assist torque determination means shown in FIG. 1 is a block diagram showing main electrical configurations of an ECU and a motor drive circuit of an electric power steering apparatus according to a first embodiment of the present invention. It is a flowchart which shows the flow of the abnormality detection process of the angle sensor by 1st Embodiment of this invention. FIG. 21 is a flowchart showing a flow of steering angle estimation processing shown in FIG. 20. FIG. It is a flowchart which shows the flow of the abnormality detection process of the angle sensor by 2nd Embodiment of this invention. It is a flowchart which shows the flow of the steering angle estimation process shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power steering device 11 Steering wheel 12 Steering shaft 13 Pinion shaft (steering mechanism shaft)
14 Torsion bar (elastic member)
15 Angle sensor (first angle detection means)
16 Angle sensor (second angle detection means)
18 rack and pinion (steering mechanism)
19 Motor rotation angle sensor (Motor rotation angle detection estimation means)
20 ECU
21, 31, 41, 51, 61, 71, 81, 91, 111, 121, 131
Assist torque determination means (assist force determination means)
23 Current control means 25 Motor drive means 27 Motor current detection means 43, 53, 63, 73, 83, 93, 123, 133
Angle sensor abnormality detection means (abnormality detection means)
55, 77 Vehicle speed sensor (vehicle speed detection estimation means)
65, 75 Steering angular velocity estimating means 85 Output limit gain calculating section 95 Output current maximum value limiting means 97 Output current maximum value limit calculating section 127 Steering angle estimating means M Motor θ ₁ Steering shaft rotation angle θ ₂ Pinion shaft rotation angle ( Rotation angle of steering mechanism shaft)
Δθ _H Torsion bar twist angle (deviation)

Claims (6)

An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the first angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α10 of both angles Is a predetermined value α11 or more and a predetermined value α12 or less , and when the predetermined value α11 is the predetermined value α12 or less , or the rotation angle of the steering shaft detected by the first angle detection means, and the steering angle estimation means When the estimated rotation angle of the steering shaft estimated by the above is rotated in the opposite direction, the rotation angle of the steering shaft minus the estimated rotation angle of the steering shaft is divided by the estimated rotation angle of the steering shaft. The ratio β10, which is a value obtained by reversing the sign, represents the deviation caused by the backlash of the reducer as the absolute value of the estimated rotation angle of the steering shaft When more than a predetermined value β11 is divided by a first angle abnormality detecting means for detecting that an abnormality occurs in each of the first angle detection means,
An electric power steering apparatus comprising: An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the first angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α10 of both angles is The steering shaft rotation angle detected when the state where the predetermined value α11 is equal to or greater than the predetermined value α12 and the predetermined value α11 is equal to or smaller than the predetermined value α12 continues for a predetermined time, When the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotates in a direction opposite to each other, a value obtained by subtracting the estimated rotation angle of the steering shaft from the rotation angle of the steering shaft The ratio β10, which is the value obtained by dividing the estimated rotation angle and reversing the sign, shows the deviation caused by the backlash of the reducer as the stearin. A first angle abnormality for detecting that an abnormality has occurred in each of the first angle detection means when a state where the value becomes equal to or greater than a predetermined value β11, which is a value divided by the absolute value of the estimated rotation angle of the shaft, continues for a predetermined time. Detection means;
An electric power steering apparatus comprising: An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the second angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α20 of both angles Is a predetermined value α21 or more and a predetermined value α22 or less , and when the predetermined value α21 is the predetermined value α22 or less , or the rotation angle of the steering shaft detected by the second angle detection means, and the steering angle estimation means When the estimated rotation angle of the steering shaft estimated by the above is rotated in the opposite direction, the rotation angle of the steering shaft minus the estimated rotation angle of the steering shaft is divided by the estimated rotation angle of the steering shaft. The ratio β20, which is a value obtained by reversing the sign, represents the deviation caused by the backlash of the speed reducer as the absolute value of the estimated rotation angle of the steering shaft. When more than a predetermined value β21 is divided by a second angle abnormality detecting means for detecting that an abnormality occurs in each of the second angle detecting means,
An electric power steering apparatus comprising: An electric power steering device that detects a steering state and assists steering by generating an assist force according to the steering state by a motor,
An elastic member for connecting a steering shaft connected to the steering wheel and a steering mechanism shaft connected to the steering mechanism so as to be relatively rotatable;
A speed reducer that transmits the assist force of the motor to the steering mechanism shaft at a predetermined speed reduction ratio;
First angle detection means for detecting a rotation angle of the steering shaft;
Second angle detection means for detecting a rotation angle of the steering mechanism shaft;
The motor generated by the motor based on either the rotation angle of the steering shaft detected by the first angle detection means or the rotation angle of the steering mechanism shaft detected by the second angle detection means. Assist force determining means for determining the assist force;
Motor rotation angle detection estimating means for detecting or estimating the rotation angle of the motor;
Steering angle estimation means for estimating the rotation angle of the steering shaft based on the motor rotation angle detected or estimated by the motor rotation angle detection estimation means;
When the rotation angle of the steering shaft detected by the second angle detection means and the estimated rotation angle of the steering shaft estimated by the steering angle estimation means rotate in the same direction, the ratio α20 of both angles is When the state where the predetermined value α21 is equal to or greater than the predetermined value α22 and is equal to or smaller than the predetermined value α22 continues for a predetermined time, or the rotation angle of the steering shaft detected by the second angle detection means When the estimated rotation angle of the steering shaft estimated by the steering angle estimating means rotates in the opposite direction, a value obtained by subtracting the estimated rotation angle of the steering shaft from the rotation angle of the steering shaft The ratio β20, which is a value obtained by dividing the estimated rotation angle and reversing the sign, shows the deviation caused by the backlash of the reducer as the stearin. A second angle abnormality for detecting that an abnormality has occurred in the second angle detection means when a state where the value becomes equal to or greater than a predetermined value β21, which is a value divided by the absolute value of the estimated rotation angle of the shaft, continues for a predetermined time. And an electric power steering apparatus. The predetermined value α11, the predetermined value α12, and the predetermined value β11 are:
3. The method according to claim 1, wherein the steering angle changes based on a rotation angle of the steering shaft detected by the first angle detection unit or an estimated rotation angle of the steering shaft estimated by the steering angle estimation unit. The electric power steering apparatus as described. The predetermined value α21, the predetermined value α22, and the predetermined value β21 are:
5. The method according to claim 3, wherein the steering angle changes based on the rotation angle of the steering shaft detected by the second angle detection unit or the estimated rotation angle of the steering shaft estimated by the steering angle estimation unit. The electric power steering apparatus as described.

Images