JP2015189416A - Electric power steering device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which can effectively suppress an influence of an input of disturbance, in a constitution for setting a correction current on the basis of a detection value which is detected by torque detection means.SOLUTION: An electric power steering device comprises: a torque sensor which detects torque generated between a steering shaft and a pinion shaft; a control torque value setting part 26 which corrects detection torque T detected by the torque sensor; a fundamental target current calculation part which sets a fundamental target current on the basis of a control torque value Tc which is corrected by the control torque value setting part 26; a steering retention auxiliary current calculation part which sets a steering retention auxiliary current for correcting a target current on the basis of the control torque value Tc; and a target current deciding part which sets the target current on the basis of the fundamental target current and the steering retention auxiliary current. The control torque value setting part 26 corrects the detection torque T on the basis of deviation between a standard rack axial force Frm which is calculated by a standard rack axial force calculation part 262a, and an actual rack axial force Fra which is calculated by an actual rack axial force calculation part 262b.

Description

  The present invention relates to an electric power steering apparatus and a program.

In recent years, in an electric power steering apparatus, a technique for setting a correction control amount for correction control in addition to basic control based on a steering torque detected by a torque sensor has been proposed.
For example, the power steering device described in Patent Document 1 includes a motor that generates auxiliary steering torque, and a control amount setting unit that sets a control amount Ic for controlling the motor according to the steering torque of the driver; A cross slope detector for detecting a cross slope of a road on which the vehicle is traveling, a correction control amount setting section for setting a correction control amount Is for controlling the motor in accordance with the detected cross slope, a control amount Ic, It comprises an adder that adds the correction control amount Is ′ that has been gain-corrected, and a control unit that drives and controls the motor based on the added value.
Thus, the control amount setting unit and the correction control amount setting unit in the power steering device described in Patent Document 1 both set the control amount Ic and the correction control amount Is based on the steering torque detected by the torque sensor. .

JP 2006-44505 A

The correction control in the power steering device described in Patent Document 1 is a correction control for controlling the motor in accordance with the crossing gradient of the road on which the vehicle is traveling. However, in other correction control, a torque sensor (torque detection) is used. It is conceivable to set the correction current based on the detected value detected in the means).
On the other hand, in a power steering apparatus, it is important to consider disturbance input due to changes in the road surface.
The present invention provides an electric power steering apparatus that can more efficiently suppress the influence of disturbance input in a configuration in which a correction current is set based on a detection value detected by a torque detection means. Objective.

  For this purpose, the present invention provides an axial force applied to an electric motor that applies an assisting force to the steering wheel of a vehicle, a steering shaft that rotates in conjunction with the steering wheel, and a rack shaft that rolls rolling wheels. Torque detecting means for detecting torque generated between the pinion shaft and the torque correcting means for correcting the detected torque detected by the torque detecting means, and the detected torque after correction corrected by the torque correcting means. Basic target current setting means for setting a basic target current that is the basis of the target current supplied to the electric motor based on the corrected torque, and correction for setting a correction current for correcting the target current based on the corrected torque Target current setting means for setting the target current based on current setting means, the basic target current and the correction current The torque correction means includes a reference rack axial force that is a reference for an axial force generated in the rack shaft based on a steering angle that is a rotation angle of the steering wheel and a vehicle speed that is a moving speed of the vehicle. A reference rack axial force calculation means for calculating, and an actual rack axial force calculation means for calculating an actual rack axial force that is an actual axial force generated on the rack shaft, and the reference rack axial force calculation means calculates In the electric power steering apparatus, the detected torque is corrected based on a deviation between the reference rack axial force and the actual rack axial force calculated by the actual rack axial force calculating unit.

Here, the torque correction means may correct the detected torque based on the vehicle speed.
The torque correction means may correct the detected torque based on the rotational speed of the electric motor.

  From another point of view, the present invention occurs between a steering shaft that rotates in conjunction with a steering wheel of a vehicle and a pinion shaft that applies an axial force to a rack shaft that rolls rolling wheels. A torque correction function that corrects a detected torque that is a detected value of torque, and a basic target current that is the basis of a target current that is supplied to the electric motor based on a corrected torque that is a corrected detected torque corrected by the torque correction function A basic target current setting function for setting the target current based on the corrected target torque, a correction current setting function for setting a correction current for correcting the target current based on the corrected torque, and the target current based on the basic target current and the correction current. A target current setting function for setting, and the torque correction function includes a steering angle that is a rotation angle of the steering wheel and a vehicle A reference rack axial force calculation function for calculating a reference rack axial force that is a reference for an axial force generated on the rack shaft based on a vehicle speed that is a dynamic speed, and an actual rack axial force that is an actual axial force generated on the rack shaft An actual rack axial force calculating function for calculating the difference between the reference rack axial force calculated by the reference rack axial force calculating function and the actual rack axial force calculated by the actual rack axial force calculating function. This is a program that realizes correcting the detected torque based on the above.

  According to the present invention, it is possible to more efficiently suppress the influence of disturbance input in the configuration in which the correction current is set based on the detection value detected by the torque detection means.

It is a figure showing the schematic structure of the electric power steering device concerning an embodiment. It is a schematic block diagram of a control apparatus. It is a schematic block diagram of a control part. It is a schematic block diagram of a basic target current calculation part. It is the schematic of the control map which shows a response | compatibility with the torque value for control, vehicle speed, and a base current. It is a schematic block diagram of a steering auxiliary current calculation part. It is a schematic block diagram of an inclination angle detection part. It is the schematic of the control map which shows a response | compatibility with a total torque and a base inclination angle. It is the schematic of the control map which shows a response | compatibility with an inclination angle correction coefficient and a vehicle speed. It is the schematic of the control map which shows a response | compatibility with offset amount and a vehicle speed. It is the schematic of the control map which shows a response | compatibility with a steering assistance base current, and a deviation angle. It is the schematic of the control map which shows a response | compatibility with a vehicle speed and an electric current correction coefficient. It is a schematic block diagram of the torque value setting part for control. It is the schematic of the control map which shows a response | compatibility with a vehicle speed correction coefficient and a vehicle speed. It is the schematic of the control map which shows a response | compatibility with a rotational speed correction coefficient and the absolute value of a motor rotational speed.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of an electric power steering apparatus 100 according to an embodiment.
Electric power steering device 100 (hereinafter, also simply referred to as “steering device 100”) is a steering device for arbitrarily changing the traveling direction of a vehicle, and in this embodiment, an automobile as an example of the vehicle. The structure applied to is illustrated.

  The steering apparatus 100 includes a wheel-like steering wheel 101 that is operated by a driver to change the traveling direction of the automobile, and a steering shaft 102 that is provided integrally with the steering wheel 101. . The steering device 100 includes an upper connecting shaft 103 connected to the steering shaft 102 via a universal joint 103a, and a lower connecting shaft 108 connected to the upper connecting shaft 103 via a universal joint 103b. . The lower connecting shaft 108 rotates in conjunction with the rotation of the steering wheel 101.

  Steering device 100 includes tie rods 104 connected to left and right front wheels 150 as rolling wheels, and rack shaft 105 connected to tie rods 104. Further, the steering device 100 includes a pinion 106 a that constitutes a rack and pinion mechanism together with rack teeth 105 a formed on the rack shaft 105. The pinion 106 a is formed at the lower end portion of the pinion shaft 106. The rack shaft 105, the pinion shaft 106, and the like function as a transmission mechanism that transmits the rotational operation force of the steering wheel 101 as the rolling force of the front wheel 150. The pinion shaft 106 applies a driving force (rack axial force) for rolling the front wheel 150 by rotating to the rack shaft 105 for rolling the front wheel 150.

  The steering device 100 also has a steering gear box 107 that houses the pinion shaft 106. The pinion shaft 106 is connected to the lower connection shaft 108 via the torsion bar 112 in the steering gear box 107. The steering gear box 107 has a space between the steering shaft 102 and the pinion shaft 106 based on the relative rotation angle between the lower connecting shaft 108 and the pinion shaft 106, in other words, based on the twist amount of the torsion bar 112. A torque sensor 109 is provided as an example of torque detecting means for detecting torque acting on the motor. In other words, the torque sensor 109 detects the torque acting on the torsion bar 112.

  Further, the steering device 100 includes an electric motor 110 supported by the steering gear box 107 and a speed reduction mechanism 111 that reduces the driving force of the electric motor 110 and transmits it to the pinion shaft 106. The speed reduction mechanism 111 includes, for example, a worm wheel (not shown) fixed to the pinion shaft 106, a worm gear (not shown) fixed to the output shaft of the electric motor 110, and the like. The electric motor 110 applies a driving force (rack axial force) for rolling the front wheel 150 to the rack shaft 105 by applying a rotational driving force to the pinion shaft 106. The electric motor 110 according to the present embodiment is a three-phase brushless motor having a resolver 120 that outputs a rotation angle signal θs that is linked to the motor rotation angle θ that is the rotation angle of the electric motor 110.

  In addition, the steering device 100 includes a control device 10 that controls the operation of the electric motor 110. An output signal from the torque sensor 109 described above is input to the control device 10. In addition, the control device 10 includes a vehicle speed sensor 170 that detects a vehicle speed Vc, which is a moving speed of the vehicle, via a network (CAN) that performs communication for sending signals for controlling various devices mounted on the vehicle. An output signal from the yaw rate sensor 180 or the like is input.

  The steering device 100 configured as described above drives the electric motor 110 based on the detected torque T detected by the torque sensor 109 and transmits the generated torque of the electric motor 110 to the pinion shaft 106. Thereby, the torque generated by the electric motor 110 assists the driver's steering force applied to the steering wheel 101.

Next, the control device 10 will be described.
FIG. 2 is a schematic configuration diagram of the control device 10.
The control device 10 is an arithmetic and logic circuit composed of a CPU, ROM, RAM, backup RAM, and the like.
The control device 10 includes a torque signal Td obtained by converting the detected torque T detected by the torque sensor 109 described above into an output signal, and a vehicle speed signal v obtained by converting the vehicle speed Vc detected by the vehicle speed sensor 170 into an output signal. The rotation angle signal θs from the resolver 120 is input.

Then, the control device 10 calculates (sets) a target current It to be supplied to the electric motor 110, and a control unit that performs feedback control based on the target current It calculated by the target current calculation unit 20. 30.
Further, the control device 10 calculates the motor rotation speed Nm based on the motor rotation angle calculation unit 71 that calculates the motor rotation angle θ of the electric motor 110 and the motor rotation angle θ calculated by the motor rotation angle calculation unit 71. A motor rotation speed calculation unit 72 to calculate and a steering angle calculation unit 73 to calculate a steering angle Ra that is a rotation angle of the steering wheel 101 are provided.

First, the target current calculation unit 20 will be described in detail.
The target current calculation unit 20 includes a control torque value setting unit 26 as an example of a torque correction unit that sets a control torque value Tc that is a torque value used for controlling the electric motor 110 based on the torque signal Td, and a control. An example of basic target current setting means for calculating (setting) a basic target current Itf that is the basis of the target current It supplied to the electric motor 110 based on the control torque value Tc and the vehicle speed Vc set by the torque value setting unit 26. And a basic target current calculation unit 27. Further, the target current calculation unit 20 is a current for the electric motor 110 to provide an assist force according to the steering state of the steering wheel 101 based on the control torque value Tc set by the control torque value setting unit 26. A steering auxiliary current calculating unit 28 for calculating (setting) the steering auxiliary current Ih, and target current setting means for finally determining (setting) the target current It based on the basic target current Itf and the auxiliary steering current Ih. And a target current determination unit 29 as an example.
The control torque value setting unit 26, the basic target current calculation unit 27, the steering auxiliary current calculation unit 28, and the target current determination unit 29 will be described in detail later.

FIG. 3 is a schematic configuration diagram of the control unit 30.
As shown in FIG. 3, the control unit 30 includes a motor drive control unit 31 that controls the operation of the electric motor 110, a motor drive unit 32 that drives the electric motor 110, and an actual current Im that actually flows through the electric motor 110. And a motor current detection unit 33 for detection.
The motor drive control unit 31 is based on a deviation between the target current It finally determined by the target current calculation unit 20 and the actual current Im supplied to the electric motor 110 detected by the motor current detection unit 33. A feedback (F / B) control unit 40 that performs feedback control, and a PWM signal generation unit 60 that generates a PWM (pulse width modulation) signal for PWM driving the electric motor 110.

  The feedback control unit 40 includes a deviation calculating unit 41 for obtaining a deviation between the target current It finally determined by the target current calculating unit 20 and the actual current Im detected by the motor current detecting unit 33, and the deviation is A feedback (F / B) processing unit 42 that performs feedback processing so as to be zero.

The feedback (F / B) processing unit 42 performs feedback control so that the target current It and the actual current Im match. For example, the feedback (F / B) processing unit 42 is proportional to the deviation calculated by the deviation calculating unit 41. Is proportionally processed, integrated by an integral element, and these values are added by an addition operation unit.
The PWM signal generation unit 60 generates a PWM signal for driving the electric motor 110 by PWM (pulse width modulation) based on the output value from the feedback control unit 40, and outputs the generated PWM signal.

The motor drive unit 32 is a so-called inverter, and includes, for example, six independent transistors (FETs) as switching elements. Three of the six transistors are a positive line of a power source, an electric coil of each phase, The other three transistors are connected to the electric coil of each phase and the negative side (ground) line of the power source. Then, the driving of the electric motor 110 is controlled by driving the gates of two transistors selected from the six and switching the transistors.
The motor current detection unit 33 detects the value of the actual current Im flowing through the electric motor 110 from the voltage generated at both ends of the shunt resistor connected to the motor drive unit 32.

The motor rotation angle calculation unit 71 (see FIG. 2) calculates the motor rotation angle θ based on the rotation angle signal θs from the resolver 120.
The motor rotation speed calculation unit 72 (see FIG. 2) calculates the motor rotation speed Nm of the electric motor 110 based on the motor rotation angle θ calculated by the motor rotation angle calculation unit 71.

  The steering angle calculation unit 73 (see FIG. 2) is configured such that the steering wheel 101, the speed reduction mechanism 111, and the like are mechanically coupled, so that the rotation angle (steering angle Ra) of the steering wheel 101 and the motor rotation angle θ of the electric motor 110 are detected. The steering angle Ra is calculated based on the motor rotation angle θ calculated by the motor rotation angle calculation unit 71. The rudder angle calculation unit 73 steers based on the integrated value of the difference between the previous value and the current value of the motor rotation angle θ that is calculated periodically (for example, every 1 millisecond) by the motor rotation angle calculation unit 71, for example. The angle Ra is calculated.

Next, the basic target current calculation unit 27 will be described in detail.
FIG. 4 is a schematic configuration diagram of the basic target current calculation unit 27.
The basic target current calculation unit 27 calculates a base current calculation unit 21 that calculates a base current Ib that is a base for setting the basic target current Itf, and an inertia compensation current Is that cancels the moment of inertia of the electric motor 110. An inertia compensation current calculation unit 22 and a damper compensation current calculation unit 23 that calculates a damper compensation current Id that limits the rotation of the electric motor 110 are provided. The basic target current calculation unit 27 determines a basic target current Itf based on the values calculated by the base current calculation unit 21, the inertia compensation current calculation unit 22, and the damper compensation current calculation unit 23. 25.
The target current calculation unit 20 includes a control torque value Tc set by the control torque value setting unit 26, a vehicle speed Vc detected by the vehicle speed sensor 170, and a motor rotation calculated by the motor rotation speed calculation unit 72. Information about the speed Nm is input.

FIG. 5 is a schematic diagram of a control map showing the correspondence between the control torque value Tc, the vehicle speed Vc, and the base current Ib.
The base current calculation unit 21 calculates a base current Ib according to the control torque value Tc set by the control torque value setting unit 26 and the vehicle speed Vc detected by the vehicle speed sensor 170. For example, the base current calculation unit 21 creates a control map illustrated in FIG. 5 that illustrates the correspondence between the control torque value Tc, the vehicle speed Vc, and the base current Ib, which is previously created based on an empirical rule and stored in the ROM. Then, the base current Ib is calculated by substituting the control torque value Tc and the vehicle speed Vc.

  The inertia compensation current calculation unit 22 cancels the moment of inertia of the electric motor 110 and the system according to the control torque value Tc set by the control torque value setting unit 26 and the vehicle speed Vc detected by the vehicle speed sensor 170. Inertia compensation current Is is calculated. For example, the inertia compensation current calculation unit 22 creates a control map on the control map that indicates the correspondence between the control torque value Tc and the vehicle speed Vc and the inertia compensation current Is, which is previously created based on an empirical rule and stored in the ROM. By substituting the torque value Tc and the vehicle speed Vc, the inertia compensation current Is is calculated.

  The damper compensation current calculation unit 23 includes the control torque value Tc set by the control torque value setting unit 26, the vehicle speed Vc detected by the vehicle speed sensor 170, and the motor rotation calculated by the motor rotation speed calculation unit 72. A damper compensation current Id that limits the rotation of the electric motor 110 according to the speed Nm is calculated. The damper compensation current calculation unit 23 indicates, for example, the correspondence between the control torque value Tc, the vehicle speed Vc, the motor rotation speed Nm, and the damper compensation current Id, which are previously created based on empirical rules and stored in the ROM. The damper compensation current Id is calculated by substituting the control torque value Tc, the vehicle speed Vc, and the motor rotation speed Nm into the control map.

  The basic target current determination unit 25 includes a base current Ib calculated by the base current calculation unit 21, an inertia compensation current Is calculated by the inertia compensation current calculation unit 22, and a damper calculated by the damper compensation current calculation unit 23. A basic target current Itf is determined based on the compensation current Id. For example, the basic target current determination unit 25 determines the current obtained by adding the inertia compensation current Is to the base current Ib and subtracting the damper compensation current Id as the basic target current Itf.

Next, the steering auxiliary current calculation unit 28 will be described in detail.
FIG. 6 is a schematic configuration diagram of the steering assist current calculation unit 28.
The steering auxiliary current calculation unit 28 includes an inclination angle detection unit 281 that detects the inclination angle As of the cross gradient based on the control torque value Tc set by the control torque value setting unit 26, and the vehicle speed sensor 170. An offset amount setting unit 282 for setting an offset amount Aso for setting a dead zone region for the inclination angle As based on the vehicle speed signal v (vehicle speed Vc). Further, the steering auxiliary current calculating unit 28 subtracts the offset amount Aso set by the offset amount setting unit 282 from the tilt angle As calculated by the tilt angle detecting unit 281, and the tilt angle As. A steering assist base current calculation unit 284 that calculates a steering assist base current Ihb that is a base of the steering assist current Ih based on a subtracted value from the offset amount Aso is provided. Further, the steering auxiliary current calculation unit 28 includes a correction coefficient setting unit 285 that sets a current correction coefficient Kc for correcting the steering auxiliary base current Ihb according to the vehicle speed Vc, and a steering auxiliary base current calculation unit 284. A multiplication unit 286 that calculates the steering holding auxiliary current Ih by multiplying the calculated steering holding base current Ihb by the current correction coefficient Kc set by the correction coefficient setting unit 285 is provided.

First, the tilt angle detector 281 will be described in detail.
FIG. 7 is a schematic configuration diagram of the tilt angle detection unit 281.
The inclination angle detection unit 281 includes a base inclination angle calculation unit 281a that calculates a base inclination angle Asb that is a base value of the inclination angle As, and an inclination angle correction coefficient setting unit 281b that sets an inclination angle correction coefficient Ka based on the vehicle speed Vc. And a base inclination angle correction unit 281c that multiplies the base inclination angle Asb and the inclination angle correction coefficient Ka.
In addition, the inclination angle detection unit 281 sets the inclination angle As based on the output from the crossing gradient travel determination unit 281d that determines whether or not the vehicle is traveling on a road having a crossing gradient, and the output from the crossing gradient travel determination unit 281d. An inclination angle setting unit 281e.

  The base inclination angle calculation unit 281a calculates the base inclination angle Asb based on the control torque value Tc set by the control torque value setting unit 26 and the target current It calculated by the target current calculation unit 20. For example, the base inclination angle calculation unit 281a adds the control torque value Tc set by the control torque value setting unit 26 and the assist torque generated by the electric motor 110 by the target current It to the base inclination corresponding to the total torque Ta. The angle Asb is calculated. The base inclination angle Asb is calculated based on the total torque Ta. On a road surface with a cross gradient, the straight traveling state of the vehicle acts between the assist torque by the electric motor 110 and the steering shaft 102 and the pinion shaft 106. This is because both the torque (mainly the driver's steering torque in the steering state) is maintained.

FIG. 8 is a schematic diagram of a control map showing the correspondence between the total torque Ta and the base inclination angle Asb. The control map shown in FIG. 8 is a schematic diagram of the control map when the vehicle speed Vc is a specific vehicle speed.
The base inclination angle calculation unit 281a, for example, adds a target current to the control map illustrated in FIG. 8 that illustrates the correspondence between the total torque Ta and the base inclination angle Asb, which is previously created based on an empirical rule and stored in the ROM. The total torque Ta is obtained by estimating the assist torque generated by the electric motor 110 based on the target current It calculated by the calculation unit 20 and adding the estimated assist torque and the control torque value Tc set by the control torque value setting unit 26. Is calculated and substituted to calculate the base inclination angle Asb.

The inclination angle correction coefficient setting unit 281b sets an inclination angle correction coefficient Ka for correcting the base inclination angle Asb calculated by the base inclination angle calculation part 281a according to the vehicle speed Vc.
FIG. 9 is a schematic diagram of a control map showing the correspondence between the inclination angle correction coefficient Ka and the vehicle speed Vc.
The inclination angle correction coefficient setting unit 281b sets the inclination angle correction coefficient Ka based on the vehicle speed Vc. For example, the inclination angle correction coefficient setting unit 281b creates a vehicle speed on the control map illustrated in FIG. 9 that shows the correspondence between the inclination angle correction coefficient Ka and the vehicle speed Vc, which is created based on an empirical rule and stored in the ROM in advance. The tilt angle correction coefficient Ka is calculated by substituting Vc.

The base inclination angle correction unit 281c multiplies the base inclination angle Asb calculated by the base inclination angle calculation unit 281a by the inclination angle correction coefficient Ka set by the inclination angle correction coefficient setting unit 281b, thereby correcting the corrected base. The inclination angle Asbc is calculated (Asbc = Asb × Ka).
In FIG. 9, considering that the self-aligning torque increases as the vehicle speed Vc increases, the inclination angle correction coefficient Ka is set to decrease as the vehicle speed Vc increases. Then, the base inclination angle correction unit 281c multiplies the base inclination angle Asb by multiplying the inclination angle correction coefficient Ka so that the inclination angle As increases as the vehicle speed Vc increases while maintaining the same inclination angle As. Correction is performed to set the inclination angle As that eliminates the self-aligning torque component. In FIG. 9, the inclination angle correction coefficient Ka for the specific vehicle speed Vc that is the basis of the control map of FIG.

  The cross gradient running determination unit 281d determines whether or not the vehicle is traveling on a road having a cross gradient. For example, the cross slope running determination unit 281d generates a cross road with a cross slope when the vehicle travels straight ahead at a predetermined speed or more with a steering torque of a predetermined value or more and the travel continues for a predetermined time or more. It is determined that the vehicle is running. That is, the cross gradient running determination unit 281d determines that the vehicle speed Vc detected by the vehicle speed sensor 170 is equal to or higher than a predetermined speed, the absolute value of the yaw rate y detected by the yaw rate sensor 180 is equal to or lower than the predetermined yaw rate, and torque When the traveling state in which the detected torque T detected by the sensor 109 is equal to or greater than a predetermined torque continues for a predetermined time or longer, it is determined that the vehicle is traveling on a road having a cross gradient.

  The inclination angle setting unit 281e determines the corrected base inclination angle Asbc calculated by the base inclination angle correction unit 281c as the inclination angle As when the crossing gradient traveling determination unit 281d determines that the vehicle is traveling on a road having a crossing gradient. In the case where the crossing gradient traveling determination unit 281d does not determine that the vehicle is traveling on a road having a crossing gradient, zero is set as the inclination angle As.

Next, the offset amount setting unit 282 will be described in detail.
FIG. 10 is a schematic diagram of a control map showing the correspondence between the offset amount Aso and the vehicle speed Vc.
The offset amount setting unit 282 sets the offset amount Aso based on the vehicle speed Vc detected by the vehicle speed sensor 170. For example, the offset amount setting unit 282 substitutes the vehicle speed Vc into the control map illustrated in FIG. 10 that shows the correspondence between the offset amount Aso and the vehicle speed Vc, which is created in advance based on empirical rules and stored in the ROM. As a result, the offset amount Aso is calculated.
The offset amount Aso is a value for setting a dead zone region for the inclination angle As based on the vehicle speed Vc detected by the vehicle speed sensor 170.

The subtraction unit 283 calculates the deviation angle ΔAs by subtracting the offset amount Aso from the inclination angle As set by the inclination angle setting unit 281e.
When the deviation angle ΔAs calculated by the subtraction unit 283 is greater than zero, the steering auxiliary base current calculation unit 284 serves as a base for the steering auxiliary current Ih for applying the auxiliary steering torque according to the deviation angle ΔAs. The holding auxiliary base current Ihb is set.

FIG. 11 is a schematic diagram of a control map showing the correspondence between the steering assist base current Ihb and the deviation angle ΔAs.
The steering assist base current calculation unit 284 sets the steering assist base current Ihb according to the deviation angle ΔAs calculated by the subtraction unit 283. The steering assist base current calculation unit 284 is, for example, a control map illustrated in FIG. 11 showing the correspondence between the steering assist base current Ihb and the deviation angle ΔAs, which is created based on an empirical rule and stored in the ROM in advance. Then, the steering assist base current Ihb is calculated by substituting the deviation angle ΔAs, and this is set as the steering assist base current Ihb.

On the other hand, when the deviation angle ΔAs calculated by the subtracting unit 283 is not larger than zero, the steering auxiliary base current calculation unit 284 sets zero as the steering auxiliary base current Ihb. That is, the steering auxiliary base current calculation unit 284 sets zero as the steering auxiliary base current Ihb when the inclination angle As set by the inclination angle setting unit 281e is smaller than the offset amount Aso.
Thus, the offset amount Aso defines a dead zone region in determining the steering assist current Ih. In the control map shown in FIG. 10, the greater the vehicle speed Vc, the smaller the offset amount Aso and the smaller the dead zone area.

FIG. 12 is a schematic diagram of a control map showing the correspondence between the vehicle speed Vc and the current correction coefficient Kc.
The correction coefficient setting unit 285 sets a current correction coefficient Kc corresponding to the vehicle speed Vc. The correction coefficient setting unit 285, for example, substitutes the vehicle speed Vc into the control map illustrated in FIG. 12 that shows the correspondence between the vehicle speed Vc and the current correction coefficient Kc, which is previously created based on empirical rules and stored in the ROM. Thus, the current correction coefficient Kc is calculated and set as the current correction coefficient Kc.

  The multiplication unit 286 calculates the steering assist current Ih by multiplying the steering assist base current Ihb set by the steering assist base current calculation unit 284 and the current correction coefficient Kc set by the correction coefficient setting unit 285. And output.

  As described above, the steering auxiliary current calculation unit 28 holds the steering angle Ra of the steering wheel 101 at the steering angle determined based on the crossing gradient when the vehicle travels straight on a road having a crossing gradient. A steering assist current Ih that causes the electric motor 110 to apply a steering assist force for this purpose is calculated. The steering assist current Ih is added to the target current It, thereby reducing the steering burden when the vehicle travels straight on a road with a crossing slope.

Then, the target current determination unit 29 uses the basic target current Itf calculated by the basic target current calculation unit 27 and the steering auxiliary current Ih calculated by the steering auxiliary current calculation unit 28 stored in a storage area such as a RAM. The added value is determined as the target current It.
As described above, the steering assist current Ih is an example of a correction current for correcting the target current It, and the steering assist current calculation unit 28 functions as an example of a correction current setting unit.

Next, the control torque value setting unit 26 will be described in detail.
FIG. 13 is a schematic configuration diagram of the control torque value setting unit 26.
The control torque value setting unit 26 compensates the phase of the detected torque T detected by the torque sensor 109, and a correction torque that sets a correction torque value Tf for correcting the control torque value Tc. A value setting unit 262. Further, the control torque value setting unit 26 controls the control torque value Tc based on the compensation detection torque T ′ whose phase is compensated by the phase compensation unit 261 and the correction torque value Tf set by the correction torque value setting unit 262. Is provided with a control torque value determining unit 263 for determining

  The correction torque value setting unit 262 includes a reference rack axial force calculation unit 262 a that calculates a reference rack axial force Frm that is a reference axial force generated on the rack shaft 105, and an actual rack that is an actual axial force generated on the rack shaft 105. An actual rack axial force calculation unit 262b that calculates the axial force Fra. Further, the correction torque value setting unit 262 is a rack axial force deviation which is a deviation between the standard rack axial force Frm calculated by the standard rack axial force calculation unit 262a and the actual rack axial force Fra calculated by the actual rack axial force calculation unit 262b. A rack axial force deviation calculating unit 262c that calculates ΔFr, and a base correction torque that sets a base correction torque value Tfb that is a base of the correction torque value Tf based on the rack axial force deviation ΔFr calculated by the rack axial force deviation calculating unit 262c. A value setting unit 262d. The correction torque value setting unit 262 also includes a vehicle speed correction coefficient setting unit 262e that sets a vehicle speed correction coefficient Kv for correcting the correction torque value Tf based on the vehicle speed Vc, and a correction torque value Tf based on the motor rotation speed Nm. A rotation speed correction coefficient setting unit 262f for setting a rotation speed correction coefficient Km for correcting The correction torque value setting unit 262 includes a base correction torque value Tfb set by the base correction torque value setting unit 262d, a vehicle speed correction coefficient Kv set by the vehicle speed correction coefficient setting unit 262e, and a rotation speed correction coefficient setting unit 262f. A correction torque value determination unit 262g that determines a correction torque value Tf based on the set rotation speed correction coefficient Km is provided.

  The reference rack axial force calculation unit 262a calculates a reference rack axial force Frm based on the steering angle Ra calculated by the steering angle calculation unit 73 and the vehicle speed Vc detected by the vehicle speed sensor 170. That is, the reference rack axial force calculation unit 262a calculates the reference rack axial force Frm corresponding to the steering angle Ra and the vehicle speed Vc. Note that the reference rack axial force calculation unit 262a is, for example, a control map or calculation indicating the correspondence between the rudder angle Ra and the vehicle speed Vc and the reference rack axial force Frm, which is previously created based on empirical rules and stored in the ROM. The reference rack axial force Frm is calculated by substituting the steering angle Ra and the vehicle speed Vc into the equation.

The actual rack axial force calculation unit 262b includes the detected torque T detected by the torque sensor 109, the motor rotation angle θ calculated by the motor rotation angle calculation unit 71, and the actual torque detected by the motor current detection unit 33. The actual rack axial force Fra is calculated based on the current Im.
Here, since the steering device 100 according to the present embodiment is a pinion type device, the actual rack axial force Fra is assumed to be equal to the axial force applied from the pinion shaft 106, and the pinion torque applied to the pinion shaft 106 Calculation is based on Tp. The actual rack axial force Fra is a value obtained by dividing the pinion torque Tp by the pitch circle radius rp of the pinion 106a (Fra = Tp / rp).

  The pinion torque Tp can be estimated as a torque obtained by adding a torque (detected torque T) acting between the steering shaft 102 and the pinion shaft 106 and a motor torque Tm applied from the output shaft torque To of the electric motor 110. (Tp = T + Tm).

The motor torque Tm is a value obtained by multiplying the output shaft torque To by the reduction ratio (gear ratio) N of the reduction mechanism 111 (Tm = To × N).
For the output shaft torque To, the motor rotation angle θ calculated by the motor rotation angle calculation unit 71 and the actual current Im detected by the motor current detection unit 33 are substituted into a calculation formula stored in the ROM in advance. This can be calculated. Instead of using the motor rotation angle θ calculated by the motor rotation angle calculation unit 71, a motor rotation angle θ calculated from a motor back electromotive force by a predetermined formula may be used.

  The rack axial force deviation calculation unit 262c subtracts the reference rack axial force Frm calculated by the reference rack axial force calculation unit 262a from the actual rack axial force Fra calculated by the actual rack axial force calculation unit 262b, thereby obtaining the rack axial force deviation ΔFr. Is calculated (ΔFr = Fra−Frm).

  The base correction torque value setting unit 262d sets a value obtained by multiplying the rack axial force deviation ΔFr calculated by the rack axial force deviation calculation unit 262c by the pitch circle radius rp of the pinion 106a as the base correction torque value Tfb ( Tfb = ΔFr × rp).

FIG. 14 is a schematic diagram of a control map showing the correspondence between the vehicle speed correction coefficient Kv and the vehicle speed Vc.
The vehicle speed correction coefficient setting unit 262e sets the vehicle speed correction coefficient Kv based on the vehicle speed Vc detected by the vehicle speed sensor 170. The vehicle speed correction coefficient setting unit 262e, for example, sets the vehicle speed Vc on the control map illustrated in FIG. 14 that shows the correspondence between the vehicle speed correction coefficient Kv and the vehicle speed Vc, which is previously created based on an empirical rule and stored in the ROM. By substituting, the vehicle speed correction coefficient Kv is calculated.

FIG. 15 is a schematic diagram of a control map showing the correspondence between the rotational speed correction coefficient Km and the absolute value of the motor rotational speed Nm.
The rotation speed correction coefficient setting unit 262f sets the rotation speed correction coefficient Km based on the absolute value of the motor rotation speed Nm calculated by the motor rotation speed calculation unit 72. The rotational speed correction coefficient setting unit 262f is exemplified in FIG. 15 showing the correspondence between the rotational speed correction coefficient Km and the absolute value of the motor rotational speed Nm, which is created in advance based on empirical rules and stored in the ROM, for example. The rotational speed correction coefficient Km is calculated by substituting the absolute value of the motor rotational speed Nm into the control map.

  The correction torque value determining unit 262g is set by the base correction torque value Tfb set by the base correction torque value setting unit 262d, the vehicle speed correction coefficient Kv set by the vehicle speed correction coefficient setting unit 262e, and the rotation speed correction coefficient setting unit 262f. A value obtained by multiplying the rotation speed correction coefficient Km is determined as a correction torque value Tf (Tf = Tfb × Kv × Km).

  The control torque value determination unit 263 controls the value obtained by adding the compensation detection torque T ′ whose phase is compensated by the phase compensation unit 261 and the correction torque value Tf set by the correction torque value setting unit 262. The torque value Tc for use is determined (Tc = T ′ + Tf).

  As described above, in the target current calculation unit 20 according to the present embodiment, the control torque value setting unit 26 calculates the reference rack axial force Frm calculated based on the steering angle Ra and the vehicle speed Vc and the actual rack. A control torque value Tc obtained by correcting the detected torque T detected by the torque sensor 109 based on the deviation from the axial force Fra is set. Then, based on the control torque value Tc set by the control torque value setting unit 26, the basic target current calculation unit 27 sets a basic target current Itf that is the basis of the target current It, and the steering auxiliary current calculation unit 28 Sets the steering auxiliary current Ih. Then, the target current determining unit 29 sets a value obtained by adding the basic target current Itf and the steering assist current Ih as the target current It.

  In the control torque value setting unit 26 according to the present embodiment, the correction torque value Tf increases as the actual rack axial force Fra generated on the rack shaft 105 becomes larger than the reference rack axial force Frm, and the control torque The value Tc is set to be large. When the control torque value Tc is increased, the basic target current Itf and the steering assist current Ih are set to be increased, and the target current It is increased. On the other hand, when the actual rack axial force Fra generated in the rack shaft 105 is smaller than the reference rack axial force Frm, the correction torque value Tf becomes smaller as the actual rack axial force Fra becomes smaller than the reference rack axial force Frm. The torque value Tc is set to be small. When the control torque value Tc decreases, the basic target current Itf and the steering assist current Ih are set to decrease, and the target current It decreases.

Thus, according to the target current calculation unit 20 according to the present embodiment, even when a disturbance due to a change in road surface or the like is input, the control torque value Tc considering the disturbance input is set, and the influence of the disturbance input is affected. The basic target current Itf and the steering auxiliary current Ih that are to be suppressed are set. Then, the influence of such disturbance input is suppressed only by setting the control torque value Tc used by the basic target current calculation unit 27 and the steering auxiliary current calculation unit 28 to set the control current. So it is more efficient.
As described above, according to the steering device 100 according to the present embodiment, the disturbance input is configured in the configuration in which the basic target current Itf and the steering auxiliary current Ih are set based on the detected torque T detected by the torque sensor 109. It is possible to more efficiently suppress the influence of the above.

  In the above-described embodiment, the steering assist is a current for giving an assist force according to the steering condition of the steering wheel 101 as a correction current for correcting the target current It by adding to or subtracting from the basic target current Itf. Although the current Ih is illustrated, the current is not particularly limited to this. Any current can be used as long as it is a correction current that corrects the target current It, and it is more efficient to suppress the influence of disturbance input by setting the correction current based on the control torque value Tc. Can be done automatically.

<Description of the program>
Further, the processing performed by the control device 10 described above can be realized by cooperation of software and hardware resources. In this case, the CPU inside the control computer provided in the control device 10 executes a program that realizes each function of the control device 10 and realizes each of these functions.

  Therefore, the processing performed by the control device 10 is between the steering shaft 102 that rotates in conjunction with the steering wheel 101 of the vehicle and the pinion shaft 106 that applies axial force to the rack shaft 105 that rolls the rolling wheels. Of the target current It to be supplied to the electric motor 110 based on the torque correction function for correcting the detected torque T which is a detected value of the torque generated in the motor and the corrected torque which is the corrected detected torque T corrected by the torque correction function. A basic target current setting function for setting the basic target current Itf, a correction current setting function for setting the steering assist current Ih as an example of a correction current for correcting the target current It based on the corrected torque, and a basic target A target current setting function for setting the target current It based on the current Itf and the steering auxiliary current Ih, The correction function is a reference rack shaft that calculates a reference rack axial force Frm that is a reference for the axial force generated in the rack shaft 105 based on the steering angle Ra that is the rotation angle of the steering wheel 101 and the vehicle speed Vc that is the moving speed of the vehicle. A reference rack axial force Frm calculated by the reference rack axial force calculation function, having a force calculation function and an actual rack axial force calculation function for calculating an actual rack axial force Fra that is an actual axial force generated on the rack shaft 105 And the actual rack axial force calculation function can also be understood as a program that realizes correcting the detected torque T based on the deviation from the actual rack axial force Fra.

  The program for realizing the present embodiment can be provided not only by communication means but also by storing it in a recording medium such as a CD-ROM.

DESCRIPTION OF SYMBOLS 10 ... Control apparatus, 20 ... Target current calculation part, 21 ... Base current calculation part, 26 ... Control torque value setting part, 27 ... Basic target current calculation part, 28 ... Steering auxiliary current calculation part, 29 ... Target current determination , 30 ... control unit, 100 ... electric power steering device, 110 ... electric motor, 262 ... correction torque value setting unit, 263 ... control torque value determination unit

Claims (4)

An electric motor for applying an assisting force to the steering wheel of the vehicle;
Torque detecting means for detecting torque generated between a steering shaft that rotates in conjunction with the steering wheel and a pinion shaft that applies an axial force to a rack shaft that rolls a rolling wheel;
Torque correcting means for correcting the detected torque detected by the torque detecting means;
Basic target current setting means for setting a basic target current that is the basis of the target current supplied to the electric motor based on a corrected torque that is a corrected detected torque corrected by the torque correction means;
Correction current setting means for setting a correction current for correcting the target current based on the corrected torque;
Target current setting means for setting the target current based on the basic target current and the correction current;
With
The torque correction means includes
A reference rack axial force calculation means for calculating a reference rack axial force that is a reference for the axial force generated in the rack shaft based on a steering angle that is a rotation angle of the steering wheel and a vehicle speed that is a moving speed of the vehicle;
An actual rack axial force calculating means for calculating an actual rack axial force which is an actual axial force generated on the rack shaft;
Have
Electric power characterized in that the detected torque is corrected based on a deviation between the reference rack axial force calculated by the reference rack axial force calculating means and the actual rack axial force calculated by the actual rack axial force calculating means. Steering device. The electric power steering apparatus according to claim 1, wherein the torque correction unit corrects the detected torque based on the vehicle speed. The electric power steering apparatus according to claim 1, wherein the torque correction unit corrects the detected torque based on a rotation speed of the electric motor. On the computer,
Torque correction function that corrects the detected torque that is the detected value of the torque generated between the steering shaft that rotates in conjunction with the steering wheel of the vehicle and the pinion shaft that applies axial force to the rack shaft that rolls the rolling wheels When,
A basic target current setting function for setting a basic target current as a basis of a target current supplied to the electric motor based on a corrected torque that is a corrected detected torque corrected by the torque correction function;
A correction current setting function for setting a correction current for correcting the target current based on the corrected torque;
A target current setting function for setting the target current based on the basic target current and the correction current;
With
The torque correction function is
A reference rack axial force calculation function for calculating a reference rack axial force that is a reference for an axial force generated in the rack shaft based on a steering angle that is a rotation angle of the steering wheel and a vehicle speed that is a moving speed of the vehicle;
An actual rack axial force calculation function for calculating an actual rack axial force that is an actual axial force generated on the rack shaft;
Have
A program that realizes correcting the detected torque based on a deviation between the reference rack axial force calculated by the reference rack axial force calculation function and the actual rack axial force calculated by the actual rack axial force calculation function.

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