JPWO2019167661A1 - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily realize the same steering torque with respect to a steering angle and the like without being influenced by a road surface condition and a change in mechanical characteristics of a steering steering system over time. I will provide a. SOLUTION: In a vehicle steering device that assists and controls a steering system, a target steering torque generating unit that generates a target steering torque, a conversion unit that converts a target steering torque into a target torsion angle, and a target torsion angle. It is equipped with a torsion angle control unit that calculates a motor current command value that follows the torsion angle, and a target steering torque generation unit is equipped with a SAT information correction unit that calculates a first torque signal based on the self-aligning torque value. Then, the SAT information correction unit outputs the first torque signal as the target steering torque, and the SAT information correction unit estimates the self-aligning torque value based on the steering torque, the angle information, and the motor current command value, and the self-aligning torque. It is provided with a filter unit that performs a filter process on the value and calculates a first torque signal, and drives and controls the motor based on the motor current command value. [Selection diagram] Fig. 5

Description

The present invention relates to a high-performance steering device for vehicles that realizes a desired steering torque based on a torsion angle of a torsion bar or the like, is not affected by a road surface condition, and is not affected by changes in mechanical characteristics over time.

The electric power steering device (EPS), which is one of the steering devices for vehicles, applies an assist force (steering assist force) to the steering system of the vehicle by the rotational force of the motor, and uses the power supplied from the inverter. The driving force of the controlled motor is applied to the steering shaft or rack shaft as an assist force by a transmission mechanism including a reduction mechanism. In such a conventional electric power steering device, feedback control of the motor current is performed in order to accurately generate an assist force. The feedback control adjusts the motor applied voltage so that the difference between the steering assist command value (current command value) and the motor current detection value becomes small, and the adjustment of the motor applied voltage is generally PWM (pulse width). Modulation) Control duty is adjusted.

The general configuration of the electric power steering device will be described with reference to FIG. 1. The column shafts (steering shaft, handle shaft) 2 of the handle 1 have a reduction mechanism 3, universal joints 4a and 4b, a pinion rack mechanism 5, and a tie rod 6a. It is further connected to the steering wheels 8L and 8R via the hub units 7a and 7b via 6b. Further, the column shaft 2 having the torsion bar is provided with a torque sensor 10 for detecting the steering torque Ts of the steering wheel 1 and a steering angle sensor 14 for detecting the steering angle θh, and is a motor that assists the steering force of the steering wheel 1. 20 is connected to the column shaft 2 via the reduction mechanism 3. Electric power is supplied from the battery 13 to the control unit (ECU) 30 that controls the electric power steering device, and an ignition key signal is input via the ignition key 11. The control unit 30 calculates the current command value of the assist (steering assistance) command based on the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the EPS motor 20 is controlled by the voltage control command value Vref.

A CAN (Controller Area Network) 40 for exchanging various information on the vehicle is connected to the control unit 30, and the vehicle speed Vs can be received from the CAN 40. Further, a non-CAN 41 that transmits / receives communications other than the CAN 40, analog / digital signals, radio waves, and the like can also be connected to the control unit 30.

The control unit 30 is mainly composed of a CPU (including an MCU, an MPU, etc.), and FIG. 2 shows a general function executed by a program inside the CPU.

Explaining the function and operation of the control unit 30 with reference to FIG. 2, the steering torque Ts detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from the CAN 40) are the current command value calculation unit. It is input to 31. The current command value calculation unit 31 calculates the current command value Iref1, which is the control target value of the current supplied to the motor 20, by using the assist map or the like based on the input steering torque Ts and vehicle speed Vs. The current command value Iref1 is input to the current limiting unit 33 via the adding unit 32A, the current command value Ireffm whose maximum current is limited is input to the subtracting unit 32B, and the deviation I (=) from the fed-back motor current value Im. Ireffm-Im) is calculated, and the deviation I is input to the PI (proportional integration) control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics have been improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM-driven via the inverter 37 as the drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B.

The compensation signal CM from the compensation signal generation unit 34 is added to the addition unit 32A, and the characteristics of the steering system system are compensated by adding the compensation signal CM to improve the astringency, inertial characteristics, and the like. .. The compensation signal generation unit 34 adds the self-aligning torque (SAT) 343 and the inertia 342 by the addition unit 344, further adds the astringent 341 to the addition result by the addition unit 345, and compensates the addition result of the addition unit 345. It is a signal CM.

In this way, in the assist control of the conventional electric power steering device, the steering torque applied manually by the driver is detected by the torque sensor as the torsion torque of the torsion bar, and the assist current mainly according to the torque is detected. The motor current is controlled as. However, when the control is performed by this method, the steering torque may differ depending on the steering angle due to the difference in the road surface condition (for example, inclination). The steering torque may also be affected by variations in the motor output characteristics due to aging.

In order to solve such a problem, for example, an electric power steering device as shown in Japanese Patent No. 5208894 (Patent Document 1) has been proposed. In the electric power steering device of Patent Document 1, the steering angle or the steering torque determined based on the relationship between the steering angle or the steering torque and the response amount in order to give an appropriate steering torque based on the tactile characteristics of the driver. The target value of steering torque is set based on the relationship (steering reaction force characteristic map).

Japanese Patent No. 5208894

However, in the electric power steering device of Patent Document 1, the steering reaction force characteristic map must be obtained in advance, and control is performed based on the deviation between the target value of the steering torque and the detected steering torque. Therefore, there is a possibility that the influence on the steering torque remains.

The present invention has been made based on the above circumstances, and an object of the present invention is not affected by changes in the mechanical characteristics of the steering steering system over time, not affected by the condition of the road surface, and with respect to the steering angle and the like. An object of the present invention is to provide a steering device for a vehicle capable of easily achieving the same steering torque.

The present invention relates to a vehicle steering device that includes at least a torsion bar having an arbitrary spring constant and a sensor that detects a torsion angle of the torsion bar, and assists and controls the steering system by driving and controlling a motor. The object of the above is a target steering torque generating unit that generates a target steering torque, a conversion unit that converts the target steering torque into a target torsion angle, and a motor current that causes the torsion angle to follow the target torsion angle. A twist angle control unit that calculates a command value is provided, and the target steering torque generation unit includes a SAT information correction unit that calculates a first torque signal based on a self-aligning torque value, and obtains the first torque signal. The SAT information correction unit outputs the target steering torque to the SAT estimation unit that estimates the self-aligning torque value based on the steering torque, angle information, and the motor current command value, and the self-aligning torque value. It is achieved by providing a filter unit for calculating the first torque signal by performing a filter process on the surface and driving and controlling the motor based on the motor current command value.

Further, the object of the present invention is that the filter unit is composed of one or a plurality of filters connected in parallel, or the SAT information correction unit uses the steering torque to the first torque signal. The steering torque sensitive gain unit for multiplying the sensitive gain is further provided, or the steering torque sensitive gain is set to be large in the on-center, or the SAT information correction unit is the first. The vehicle speed-sensitive gain unit for multiplying one torque signal by the vehicle speed-sensitive gain is further provided, or the vehicle speed-sensitive gain is set to be large at high speed, or the SAT information correction unit By further providing a steering angle sensitive gain unit that multiplies the first torque signal by the steering angle sensitive gain, or by the SAT information correction unit, a limiting unit that limits the upper and lower limit values of the first torque signal is provided. Further, or by using the target steering torque generating unit, the basic map unit that obtains the second torque signal from the steering angle and the vehicle speed using the basic map, and the damper gain map that is sensitive to the vehicle speed are used for the angular speed information. A damper calculation unit that obtains a third torque signal based on the rudder, and a hysteresis correction unit that performs hysteresis correction using the steering state and the steering angle to obtain a fourth torque signal are further provided. The target steering torque is calculated from the three torque signals, at least one of the fourth torque signals, and the first torque signal, or the characteristics of the basic map and the hysteresis correction unit are vehicle speed sensitive. Thereby, or the target steering torque generation unit further includes a phase compensation unit that performs phase compensation in the front stage or the rear stage of the basic map unit, and the steering is performed via the basic map unit and the phase compensation unit. This is achieved more effectively by obtaining the second torque signal from the angle and the vehicle speed.

According to the vehicle steering device of the present invention, the torsion angle follows the target torsion angle by controlling the target torsion angle obtained based on the target steering torque generated by the target steering torque generating unit. It is possible to realize a desired steering torque and to provide an appropriate steering torque based on the driver's steering sensation.

Further, by using the self-aligning torque (SAT) value to generate the target steering torque, the road surface information during traveling can be appropriately transmitted to the driver as a steering feeling.

It is a block diagram which shows the outline of the electric power steering apparatus. It is a block diagram which shows the structural example in the control unit (ECU) of an electric power steering apparatus. It is a structural drawing which shows the installation example of an EPS steering system and various sensors. It is a block diagram which shows the structural example (1st Embodiment) of this invention. It is a block diagram which shows the structural example (first embodiment) of the target steering torque generation part. It is a diagram which shows the characteristic example of a basic map. It is a diagram which shows the characteristic example of a damper gain map. It is a diagram which shows the characteristic example of the hysteresis correction part. It is a block diagram which shows the structural example (first embodiment) of the SAT information correction part. It is an image diagram which shows the state of the torque generated from the road surface to the steering. It is a diagram which shows the characteristic example of the steering torque sensitive gain. It is a diagram which shows the characteristic example of the vehicle speed sensitive gain. It is a diagram which shows the characteristic example of the rudder angle sensitive gain. It is a diagram which shows the setting example of the upper and lower limit values in a restriction part. It is a block diagram which shows the structural example of the torsion angle control part. It is a flowchart which shows the operation example (1st Embodiment) of this invention. It is a flowchart which shows the operation example (1st Embodiment) of the target steering torque generation part. It is a flowchart which shows the operation example of the torsion angle control part. It is a graph which shows the state of the change of the SAT value and the steering torque when there is no SAT information correction part in the simulation which shows the effect of the SAT information correction part. It is a graph which shows the state of change of the SAT value, the torque signal and the steering torque when there is a SAT information correction part in the simulation which shows the effect of the SAT information correction part. It is a block diagram which shows the structural example (second embodiment) of the filter part. It is a block diagram which shows the structural example (third embodiment) of the target steering torque generation part. It is a block diagram which shows the structural example (fourth embodiment) of this invention. It is a block diagram which shows the insertion example of a phase compensation part. It is a block diagram which shows the outline of the SBW system. It is a block diagram which shows the structural example (fifth embodiment) of this invention. It is a block diagram which shows the structural example of the target steering angle generation part. It is a block diagram which shows the structural example of the steering angle control part. It is a flowchart which shows the operation example (fifth embodiment) of this invention.

The present invention is a vehicle steering device for achieving the same steering torque with respect to the steering angle and the like without being affected by the condition of the road surface, and the torsion angle of the torsion bar and the like is set to a value according to the steering angle and the like. The desired steering torque is realized by controlling so as to follow.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, an installation example of various sensors for detecting information related to an electric power steering device, which is one of the steering devices for vehicles according to the present invention, will be described. FIG. 3 is a diagram showing an installation example of the EPS steering system and various sensors, and the column shaft 2 is provided with a torsion bar 2A. The road surface reaction force Rr and the road surface information μ act on the steering wheels 8L and 8R. An upper angle sensor is provided on the handle side of the column shaft 2 across the torsion bar 2A, and a lower angle sensor is provided on the steering wheel side of the column shaft 2 across the torsion bar 2A. Detects the handle angle θ ₁ , and the lower angle sensor detects the column angle θ ₂ . The steering angle θh is detected by a steering angle sensor provided on the upper part of the column shaft 2, _{and from the deviations of the steering wheel angle θ 1} and the column angle θ ₂ , the torsion bar torsion angle Δθ and torsion bar torque are determined by the following equations 1 and 2. Tt can be calculated. Kt is the spring constant of the torsion bar 2A.

トーションバートルクＴｔは、例えば特開２００８−２１６１７２号公報で示されるトルクセンサを用いて検出することも可能である。なお、本実施形態では、トーションバートルクＴｔを操舵トルクＴｓとしても扱うこととする。

The torsion bar torque Tt can also be detected using, for example, a torque sensor disclosed in Japanese Patent Application Laid-Open No. 2008-216172. In the present embodiment, the torsion bar torque Tt is also treated as the steering torque Ts.

Next, a configuration example of the present invention will be described.

FIG. 4 is a block diagram showing a configuration example (first embodiment) of the present invention, in which the driver's steering wheel steering is assist-controlled by a motor in the EPS steering system / vehicle system 100. In addition to the steering angle θh and the vehicle speed Vs, the target steering torque generation unit 200 that outputs the target steering torque Tref has the steering torque Ts, the motor angle θm that is the angle information, and the motor current command output from the torsion angle control unit 300. The value Imc and the right-turn or left-turn steering state STs output from the right-turn / left-turn determination unit 400 are input. The target steering torque Tref is converted into a target torsion angle Δθref by the conversion unit 500, and the target torsion angle Δθref is input to the torsion angle control unit 300 together with the torsion angle Δθ of the torsion bar 2A and the motor angular velocity ωm. The twist angle control unit 300 calculates a motor current command value Imc such that the twist angle Δθ becomes a target twist angle Δθref, and the motor of the EPS is driven by the motor current command value Imcc.

The right-turn / left-turn determination unit 400 determines whether the steering is right-turn or left-turn based on the motor angular velocity ωm, and outputs the determination result as the steering state STs. That is, when the motor angular velocity ωm is a positive value, it is determined as “right turn”, and when it is a negative value, it is determined as “left turn”. Instead of the motor angular speed .omega.m, the steering angle [theta] h, may be used an angular velocity that is calculated by performing the speed calculation with respect to the handle angle theta ₁ or column angle theta _2.

FIG. 5 shows a configuration example of the target steering torque generation unit 200. The target steering torque generation unit 200 includes a basic map unit 210, a differentiation unit 220, a damper gain unit 230, a hysteresis correction unit 240, a SAT information correction unit 250, and multiplication. A unit 260 and addition units 261, 262 and 263 are provided, and the steering angle θh is input to the basic map unit 210, the differential unit 220, the hysteresis correction unit 240 and the SAT information correction unit 250, and is output from the right / left turn determination unit 400. The steering state STs to be performed are input to the hysteresis correction unit 240, the steering torque Ts, the motor angle θm and the motor current command value Imc are input to the SAT information correction unit 250, and the vehicle speed Vs is the basic map unit 210, the damper gain unit 230 and the SAT. It is input to the information correction unit 250.

The basic map unit 210 has a basic map, and outputs a torque signal (second torque signal) Tref_a having a vehicle speed Vs as a parameter as shown in FIG. 6 using the basic map. That is, the torque signal Tref_a increases as the magnitude (absolute value) | θh | of the steering angle θh increases, and increases as the vehicle speed Vs increases. The code unit 211 outputs the code (+1 or -1) of the steering angle θh to the multiplication unit 212. The magnitude of the torque signal Tref_a is obtained from the magnitude of the steering angle θh by a map, and this is multiplied by the sign of the steering angle θh to calculate the torque signal Tref_a. In FIG. 6, the basic map unit 210 is composed of the map, the sign unit, and the multiplication unit that refer to the magnitude | θh | of the steering angle θh, but the map may be configured according to the positive and negative steering angles θh. In this case, the mode of change may be changed depending on whether the steering angle θh is positive or negative. Further, although the basic map shown in FIG. 6 is vehicle speed sensitive, it does not have to be vehicle speed sensitive.

The differentiation unit 220 differentiates the steering angle θh to calculate the steering angle velocity ωh, which is the angular velocity information, and the steering angle velocity ωh is input to the multiplication unit 260.

Damper gain unit 230 outputs the damper gain _{D G} is multiplied by the steering angular speed [omega] h. Steering angular velocity ωh, which is multiplied by the damper gain _{D G} at multiplying unit 260 is inputted to the torque signal addition section 262 as the (third torque signal) Tref_b. Damper gain D _G, using the damper gain map of vehicle speed sensitive type having the damper gain unit 230 is determined according to the vehicle speed Vs. The damper gain map has a characteristic that it gradually increases as the vehicle speed Vs increases, as shown in FIG. 7, for example. The damper gain map may be variable according to the steering angle θh. The damper gain unit 230 and the multiplication unit 260 constitute a damper calculation unit.

The hysteresis correction unit 240 calculates the torque signal (fourth torque signal) Tref_c according to the following equation 3 based on the steering angle θh and the steering state STs. In the following equation 3, x = θh, y = Tref_c, a> 1, c> 0, and A _hys is the hysteresis width.

右切り操舵から左切り操舵、左切り操舵から右切り操舵へ切り替える際に、最終座標（ｘ１，ｙ１）の値に基づき、切り替え後の数３の“ｂ”に以下の数４を代入する。これにより、切り替え前後の連続性が保たれる。

When switching from right-turn steering to left-turn steering and from left-turn steering to right-turn steering, the following equation 4 is substituted into "b" of equation 3 after switching based on the values of the final coordinates (x1, y1). As a result, continuity before and after switching is maintained.

上記数４は、上記数３中のｘにｘ１を、ｙ_Ｒ及びｙ_Ｌにｙ１を代入することにより導出することができる。

The above number 4 can be derived by substituting _{x1 for x and y1 for y R} and y _{L in the above number 3.}

Any positive number larger than 1 can be used as "a". For example, when the Napier number "e" is used, the numbers 3 and 4 become the following numbers 5 and 6.

数５及び数６においてＡ_ｈｙｓ＝１［Ｎｍ］、ｃ＝０．３と設定し、０［ｄｅｇ］から開始し、＋５０［ｄｅｇ］、−５０［ｄｅｇ］の操舵をした場合の、ヒステリシス補正されたトルク信号Ｔｒｅｆ＿ｃの線図例を図８に示す。即ち、ヒステリシス補正部２４０からのトルク信号Ｔｒｅｆ＿ｃは、０の原点→Ｌ１（細線）→Ｌ２（破線）→Ｌ３（太線）のようなヒステリシス特性である。

_{Hysteresis correction when A hys} = 1 [Nm] and c = 0.3 are set in Equations 5 and 6 and the steering is started from 0 [deg] and steered at +50 [deg] and -50 [deg]. FIG. 8 shows an example of a diagram of the torque signal Tref_c. That is, the torque signal Tref_c from the hysteresis correction unit 240 has a hysteresis characteristic such as the origin of 0 → L1 (thin line) → L2 (broken line) → L3 (thick line).

_{A hys,} which is a coefficient representing the output width of the hysteresis characteristic, and c, which is a coefficient representing roundness, may be made variable according to the vehicle speed Vs and / or the steering angle θh.

The SAT information correction unit 250 estimates the self-aligning torque (SAT) based on the steering torque Ts, the motor angle θm, and the motor current command value Imc, and further performs filtering, gain multiplication, and limiting processing to obtain a torque signal (SAT). 1st torque signal) Tref_d is calculated. FIG. 9 shows a configuration example of the SAT information correction unit 250. The SAT information correction unit 250 includes a SAT estimation unit 251 and a filter unit 252, a steering torque sensitive gain unit 253, a vehicle speed sensitive gain unit 254, and a steering angle sensitive gain unit 255. And a limiting unit 256.

Here, the state of the torque generated between the road surface and the steering wheel will be described with reference to FIG. When the driver steers the steering wheel, steering torque Ts is generated, and the motor 20 generates assist torque (column shaft conversion value of motor torque) Tm according to the steering torque Ts. As a result, the wheels are steered and SAT T _SAT is generated as a reaction force. At that time, torque that becomes resistance of steering wheel steering is generated by column shaft conversion inertia (inertia acting on the column shaft by the motor (rotor), reduction mechanism, etc.) J and friction (static friction) Fr. Further, the rotational speed of the motor 20, the physical torque expressed as a damper section (damper coefficient D _M) (viscous torque) is generated. From the balance of these forces, the equation of motion as shown in Equation 7 below can be obtained.

ω_Ｍ及びα_Ｍはコラム軸換算（コラム軸に対する値に変換）されたモータ角速度及びモータ角加速度である。そして、上記数７をＴ_ＳＡＴについて解くと下記数８が得られる。

ω _M and α _M are the motor angular velocity and the motor angular acceleration converted to the column axis (converted to the value with respect to the column axis). Then, when the above number 7 is _{solved for T SAT} , the following number 8 is obtained.

上記数８からわかるように、コラム軸換算慣性Ｊ、静摩擦Ｆｒ及びダンパ係数Ｄ_Ｍを定数として予め求めておくことで、モータ角速度ω_Ｍ、モータ角加速度α_Ｍ、アシストトルクＴｍ及び操舵トルクＴｓよりセルフアライニングトルク値（ＳＡＴ値）Ｔ_ＳＡＴを推定することができる。なお、コラム軸換算慣性Ｊは、簡易的にモータ慣性と減速比の関係式を用いてコラム軸に換算した値でも良い。

As can be seen from Equation 8, by previously seeking the column shaft conversion inertia J, the static friction Fr and the damper coefficient D _M as a constant, the motor angular velocity omega _M, the motor angular acceleration alpha _M, from the assist torque Tm and the steering torque Ts The self-aligning torque value (SAT value) T _SAT can be estimated. The column shaft conversion inertia J may be a value converted to the column shaft simply by using the relational expression of the motor inertia and the reduction ratio.

The SAT estimation unit 251 inputs the steering torque Ts, the motor angle θm, and the motor current command value Imc, and estimates the _{self-aligning torque value (SAT value) T SAT based on the equation 8.} The motor current command value Imc is input to the conversion unit 251A, and the assist torque Tm converted to the column shaft is calculated by multiplying the predetermined gear ratio and torque constant. The motor angle θm is input to the angular velocity calculation unit 251B, and the motor angular velocity ω _M converted to the column axis is calculated by the differential processing and the division by the gear ratio. The angular acceleration calculation unit 251C calculates _{the motor angular acceleration α M} converted to the column axis by the differential processing using the _{motor angular velocity ω M.} Then, using the input steering torque Ts, the calculated assist torque Tm, the motor angular velocity ω _M, and the motor angular acceleration α _{M , the SAT value T SAT is} configured as shown in FIG. 9 based on Equation 8. Is calculated. 9, block 251D functions as a sign function, and outputs the code of the input data, block 251E outputs multiplies the damper coefficient D _M to the input data, block 251F multiplies the static friction Fr of the input data The block 251G outputs the data by multiplying the input data by the column axis conversion inertia J and outputs the data. If the column angle can be directly detected, the column angle may be used as the angle information instead of the motor angle θm. In this case, column axis conversion becomes unnecessary. Further, instead of the motor angle θm, a signal obtained by converting the motor angular velocity ωm from the EPS steering system / vehicle system 100 into a column axis may _{be input as the motor angular velocity ω M} , and the differential processing with respect to the motor angle θm may be omitted. Further, the SAT value T _SAT may be estimated by a method other than the above, and the measured value may be used instead of the estimated value.

_{In order to utilize the SAT value T SAT} estimated by the SAT estimation unit 251 and appropriately convey it to the driver as a steering feeling, the filter unit 252 _{extracts the information to be transmitted from the SAT value T SAT} , and the steering torque sensitive gain unit. The amount transmitted by 253, the vehicle speed sensitive gain unit 254 and the steering angle sensitive gain unit 255 is adjusted, and the upper and lower limit values are further adjusted by the limiting unit 256. The filter unit 252 performs a filter process on the _{SAT value T SAT} by, for example, a band bus filter, and outputs the _{SAT information T ST 1.} The steering torque sensitive gain unit 253 multiplies the steering torque sensitive gain set according to the steering torque Ts by the SAT information T _ST 1 and outputs the SAT information T _{ST 2.} The steering torque sensitive gain is set, for example, as shown in FIG. 11 so that the sensitivity becomes high in the vicinity of the on-center in the straight running state. That is, the steering torque sensitive gain is fixed at 1.0 when the steering torque Ts is Ts1 (for example, 2 Nm) or less, and fixed at a value smaller than 1.0 when the steering torque Ts is Ts2 (> Ts1) (for example, 4 Nm) or more. , The steering torque Ts is set to decrease at a constant rate between Ts1 and Ts2. The vehicle speed-sensitive gain unit 254 multiplies the vehicle speed-sensitive gain set according to the vehicle speed Vs by the SAT information T _ST 2 and outputs the SAT information T _{ST 3.} The vehicle speed-sensitive gain is set so as to increase the sensitivity at high speed, for example, as shown in FIG. That is, the vehicle speed sensitive gain is fixed at 1.0 when the vehicle speed Vs is Vs2 (for example, 70 km / h) or more, and is fixed at a value smaller than 1.0 when the vehicle speed Vs is Vs1 (<Vs2) (for example, 50 km / h) or less. Then, the vehicle speed Vs is set to increase at a constant rate between Vs1 and Vs2. The steering angle sensitive gain unit 255 multiplies the steering angle sensitive gain set according to the steering angle θh by the SAT information T _ST 3 and outputs the torque signal Tref_d0. The steering angle sensitive gain is set, for example, as shown in FIG. 13 so that the action starts from a predetermined steering angle and the sensitivity becomes high when the steering angle is large. That is, the steering angle sensitive gain is fixed at a predetermined gain value Gα when the steering angle θh is θh1 (for example, 10 deg) or less, and is fixed at 1.0 when the steering angle θh is θh2 (for example, 30 deg) or more, and the steering angle θh is θh1. It is set to increase at a constant rate between θh2. If it is desired to increase the sensitivity when the steering angle is large, Gα may be set in the range of 0 ≦ Gα <1. If it is desired to increase the sensitivity when the steering angle is small, Gα may be set in the range of 1 <Gα, although not shown. If you do not want to change the sensitivity depending on the steering angle, you can set Gα = 1. As shown in FIG. 14, the limiting unit 256 presets an upper limit value and a lower limit value for the torque signal, and if the torque signal Tref_d0 to be input is equal to or greater than the upper limit value, the upper limit value is set, and if it is equal to or less than the lower limit value, the upper limit value is set. The value is output as the torque signal Tref_d0 in other cases. The steering torque sensitive gain, the vehicle speed sensitive gain, and the steering angle sensitive gain may have curved characteristics instead of linear characteristics as shown in FIGS. 11, 12, and 13, depending on the steering feeling. The setting, for example, the maximum value and the minimum value of each gain may be adjusted as appropriate. Further, the limiting portion 256 may be deleted when there is no possibility that the magnitude of the torque signal will increase or when it is suppressed by other means. The steering torque-sensitive gain unit 253, the vehicle speed-sensitive gain unit 254, and the steering angle-sensitive gain unit 255 can also be omitted as appropriate, and the installation positions may be interchanged. A configuration in which each gain is obtained in parallel and _{multiplied by the SAT information T ST} 1 at one location may be used.

The torque signals Tref_d, Tref_c, Tref_b and Tref_a obtained as described above are sequentially added by the addition units 263, 262 and 261, and the final addition result is output as the target steering torque Tref.

The rudder angular velocity ωh is obtained by a differential calculation with respect to the steering angle θh, but a low-pass filter (LPF) process is appropriately performed in order to reduce the influence of high-frequency noise. Further, the differential operation and the LPF processing may be performed by the high-pass filter (HPF) and the gain. Further, the steering angular velocity ωh is calculated by performing differential calculation and LPF processing on _{the handle angle θ 1} detected by the upper angle sensor or the column angle θ ₂ detected by the lower angle sensor instead of the steering angle θh. Is also good. The motor angular velocity ωm may be used as the angular velocity information instead of the steering angular velocity ωh, and in this case, the differential unit 220 becomes unnecessary.

The conversion unit 500 has a characteristic of -1 / Kt in which the sign of the reciprocal of the spring constant Kt of the torsion bar 2A is inverted, and converts the target steering torque Tref into the target twist angle Δθref.

The twist angle control unit 300 calculates the motor current command value Imc based on the target twist angle Δθref, the twist angle Δθ, and the motor angular velocity ωm. FIG. 15 is a block diagram showing a configuration example of the torsion angle control unit 300. The torsion angle control unit 300 includes a torsion angle feedback (FB) compensation unit 310, a torsion angular velocity calculation unit 320, a speed control unit 330, and a stabilization compensation unit. It includes 340, an output limiting unit 350, a subtracting unit 361, and an adding unit 362. The target torsional angle Δθref output from the conversion unit 500 is added and input to the subtracting unit 361, and the twisting angle Δθ is subtracted and input to the subtracting unit 361. At the same time, it is input to the torsion angular velocity calculation unit 320, and the motor angular velocity ωm is input to the stabilization compensation unit 340.

The twist angle FB compensation unit 310 multiplies the compensation value C _{FB (transfer function) by the deviation Δθ 0 of the} target twist angle Δθref calculated by the subtraction unit 361 and the twist angle Δθ, and the twist angle Δθref is multiplied by the target twist angle Δθref. Outputs the target torsional velocity ωref that follows. The compensation value C _FB may be a simple gain Kpp or a commonly used compensation value such as a compensation value for PI control. The target torsional velocity ωref is input to the speed control unit 330. The twist angle FB compensation unit 310 and the speed control unit 330 make it possible to make the twist angle Δθ follow the target twist angle Δθref and realize a desired steering torque.

The torsion angular velocity calculation unit 320 calculates the torsion angular velocity ωt by a differential calculation with respect to the torsion angle Δθ, and the torsion angular velocity ωt is input to the velocity control unit 330. As a differential operation, pseudo-differentiation by HPF and gain may be performed. Further, the torsion angular velocity ωt may be calculated from another means or other than the torsion angle Δθ and input to the velocity control unit 330.

The speed control unit 330 calculates the motor current command value Imca1 so that the torsion angular velocity ωt follows the target torsional velocity ωref by IP control (proportional leading PI control). The subtraction unit 333 calculates the difference (ωref-ωt) between the target torsional velocity ωref and the torsional angular velocity ωt, integrates the difference with the integration unit 331 having the gain Kvi, and the integration result is additionally input to the subtraction unit 334. To. The torsion angular velocity ωt is also input to the proportional unit 332, is subjected to proportional processing by the gain Kvp, and is subtracted and input to the subtraction unit 334. The subtraction result in the subtraction unit 334 is output as the motor current command value Imca1. The speed control unit 330 is not an IP control, but a PI control, a P (proportional) control, a PID (proportional integral differential) control, a PI-D control (differential leading PID control), a model matching control, and a model norm. The motor current command value Imca1 may be calculated by a commonly used control method such as control.

The stabilization compensation unit 340 has a compensation value Cs (transfer function), and calculates the motor current command value Imca2 from the motor angular velocity ωm. If the gains of the torsion angle FB compensation unit 310 and the speed control unit 330 are increased in order to improve the followability and the disturbance characteristics, a controlled oscillation phenomenon in a high frequency region occurs. As a countermeasure, the transfer function (Cs) required for stabilizing the motor angular velocity ωm is set in the stabilization compensation unit 340. Thereby, the stabilization of the entire EPS control system can be realized. As the transfer function (Cs) of the stabilization compensation unit 340, for example, a first-order filter represented by the following equation 9 set by pseudo-differentiation and gain using a first-order HPF structure is used.

ここで、Ｋ_ｓｔａはゲインで、ｆｃは遮断周波数であり、ｆｃとして例えば１５０［Ｈｚ］を設定する。なお、伝達関数として、２次フィルタ、４次フィルタ等を使用しても良い。

Here, K _sta is a gain, fc is a cutoff frequency, and for example, 150 [Hz] is set as fc. A second-order filter, a fourth-order filter, or the like may be used as the transfer function.

The motor current command value Imca1 from the speed control unit 330 and the motor current command value Imca2 from the stabilization compensation unit 340 are added by the addition unit 362 and output as the motor current command value Imccb.

The output limiting unit 350 limits the upper and lower limits of the motor current command value Imccb and outputs the motor current command value Imcc. Similar to the limiting unit 256 in the SAT information correction unit 250, the upper limit value and the lower limit value with respect to the motor current command value Imccb are set in advance to limit.

In such a configuration, an operation example of this embodiment will be described with reference to the flowcharts of FIGS. 16 to 18.

When the operation is started, the right-turn / left-turn determination unit 400 inputs the motor angular velocity ωm, determines whether the steering is right-turn or left-turn based on the sign of the motor angular velocity ωm, and sets the determination result as the steering state STs. Output to the target steering torque generation unit 200 (step S10).

The target steering torque generation unit 200 inputs the steering angle θh, the vehicle speed Vs, the steering torque Ts, the motor angle θm, and the motor current command value Imc together with the steering state STs, and generates the target steering torque Tref (step S20). An operation example of the target steering torque generation unit 200 will be described with reference to the flowchart of FIG.

The steering angle θh input to the target steering torque generation unit 200 is the basic map unit 210, the differentiation unit 220, the hysteresis correction unit 240 and the SAT information correction unit 250, the steering state STs is the hysteresis correction unit 240, and the vehicle speed Vs is the basic map. The steering torque Ts, the motor angle θm, and the motor current command value Imc are input to the SAT information correction unit 250, respectively, to the unit 210, the damper gain unit 230, and the SAT information correction unit 250 (step S21).

Using the basic map shown in FIG. 6, the basic map unit 210 generates a torque signal Tref_a corresponding to the steering angle θh and the vehicle speed Vs, and outputs the torque signal Tref_a to the addition unit 261 (step S22).

Differentiating section 220 differentiates the steering angle θh outputs steering angular velocity [omega] h (step S23), damper gain unit 230 outputs the damper gain D _G corresponding to the vehicle speed Vs by using the damper gain map shown in FIG 7 (step S24), the multiplication unit 260 calculates a torque signal Tref_b by multiplying the steering angular velocity ωh and damper gain _{D G,} and outputs the result to adding section 262 (step S25).

The hysteresis correction unit 240 performs hysteresis correction by switching the operations according to the equations 5 and 6 with respect to the steering angle θh according to the steering state STs (step S26), generates a torque signal Tref_c, and causes the addition unit 263 to perform the hysteresis correction. Output (step S27). Although the hysteresis widths A _hys , c, x1 and y1 in the equations 5 and 6 are preset and held, b and b'are calculated in advance from the equation 6 and b and b'are replaced with x1 and y1. May be retained.

The SAT information correction unit 250 uses the input motor current command value Imc and motor angle θm as the SAT estimation unit 251 and the steering torque Ts as the SAT estimation unit 251 and the steering torque sensitive gain unit 253, and the vehicle speed Vs as the vehicle speed sensitive gain unit 254. The steering angle θh is input to the steering angle sensitive gain unit 255, respectively. The SAT estimation unit 251 calculates the assist torque Tm from the motor current command value Imc by the conversion unit 251A, and the angular velocity calculation unit 251B calculates the motor angular velocity ω _M from the motor angle θm and further via the angular acceleration calculation unit 251C. The angular acceleration α _{M is calculated, and the SAT value T SAT} is calculated based on the equation 8 by using them and the steering torque Ts (step S28). The calculated SAT value T _SAT is filtered by the filter unit 252 and output to the steering torque sensitive gain unit 253 as _{SAT information T ST 1 (step S29).} The steering torque sensitive gain unit 253 determines the steering torque sensitive gain according to the input steering torque Ts by using the characteristics as shown in FIG. 11 _{, multiplies the SAT information T ST} 1, and the SAT information T _ST 2 Is output to the vehicle speed sensitive gain unit 254 (step S30). The vehicle speed-sensitive gain unit 254 determines the vehicle speed-sensitive gain according to the input vehicle speed Vs by using the characteristics as shown in FIG. 12 _{, multiplies it by the SAT information T ST} 2, and obtains the steering angle as the _{SAT information T ST 3.} Output to the sensitive gain unit 255 (step S31). The steering angle sensitive gain unit 255 determines the steering angle sensitive gain according to the input steering angle θh using the characteristics shown in FIG. 13 _{, multiplies it by the SAT information T ST} 3, and limits it as the torque signal Tref_d0. Output to unit 256 (step S32). The limiting unit 256 limits the upper and lower limit values of the torque signal Tref_d0 by the preset upper limit value and the lower limit value, and outputs the torque signal Tref_d to the adding unit 263 (step S33).

Then, the torque signals Tref_c and Tref_d are added by the addition unit 263, the torque signal Tref_b is added to the addition result by the addition unit 262, and the torque signal Tref_a is further added to the addition result by the addition unit 261. The steering torque Tref is calculated (step S34).

The target steering torque Tref generated by the target steering torque generation unit 200 is input to the conversion unit 500, and is converted into the target twist angle Δθref by the conversion unit 500 (step S40). The target twist angle Δθref is input to the twist angle control unit 300.

The twist angle control unit 300 inputs the twist angle Δθ and the motor angular velocity ωm together with the target twist angle Δθref, and calculates the motor current command value Imc (step S50). An operation example of the twist angle control unit 300 will be described with reference to the flowchart of FIG.

The target torsion angle Δθref input to the torsion angle control unit 300 is input to the subtraction unit 361, the torsion angle Δθ is input to the subtraction unit 361 and the torsion angle velocity calculation unit 320, and the motor angular velocity ωm is input to the stabilization compensation unit 340 (step). S51).

_{In the subtraction unit 361, the deviation Δθ 0} is calculated by subtracting the torsion angle Δθ from the target torsion angle Δθref (step S52). Deviation [Delta] [theta] ₀ is input to the helix angle FB compensation unit 310, the twist angle FB compensation unit 310 compensates the deviation [Delta] [theta] ₀ is multiplied by the compensation value _{C FB} on the deviation [Delta] [theta] ₀ (step S53), the target torsion angular velocity ωref Is output to the speed control unit 330.

The torsion angular velocity calculation unit 320 that has input the torsion angle Δθ calculates the torsion angular velocity ωt by a differential calculation with respect to the torsion angle Δθ (step S54), and outputs the torsion angular velocity ωt to the speed control unit 330.

In the speed control unit 330, the difference between the target torsional velocity ωref and the torsional angular velocity ωt is calculated by the subtraction unit 333, and the difference is integrated (Kvi / s) by the integration unit 331 and additionally input to the subtraction unit 334 (step S55). ). Further, the torsion angular velocity ωt is proportionally processed (Kvp) by the proportional unit 332, the proportional result is subtracted and input to the subtraction unit 334 (step S55), and the motor current command value Imca1 which is the subtraction result of the subtraction unit 334 is output and added. It is input to the unit 362.

The stabilization compensation unit 340 performs stabilization compensation on the input motor angular velocity ωm using the transfer function Cs represented by Equation 9 (step S56), and the motor current command value Imca2 from the stabilization compensation unit 340. Is input to the addition unit 362.

The addition unit 362 adds the motor current command values Imca1 and Imca2 (step S57), and the motor current command value Imccb, which is the addition result, is input to the output limiting unit 350. The output limiting unit 350 limits the upper and lower limit values of the motor current command value Imccb by the preset upper limit value and lower limit value (step S58), and outputs the motor current command value Imcc as the motor current command value Imcc (step S59).

The motor is driven based on the motor current command value Imcc output from the torsion angle control unit 300, and current control is performed (step S60).

The order of data input and calculation in FIGS. 16 to 18 can be changed as appropriate.

The effect of the SAT information correction unit in this embodiment will be described based on the simulation results.

First, the simulation result when there is no SAT information correction unit is shown. As shown in FIG. 19A, changes in the target steering torque and the actual steering torque when the SAT value is vibrated in a sinusoidal manner with an amplitude of 1 Nm for 10 seconds at a frequency from 1 Hz to 10 Hz are shown. It is shown in FIG. 19 (B). In FIG. 19, the horizontal axis is the time [sec], the vertical axis is the SAT value [Nm] in FIG. 19 (A), and the steering torque [Nm] in FIG. 19 (B). Further, the SAT value is a value converted to the column axis, and the steering angle θh is constant at 0 [deg].

In FIG. 19B, the target steering torque is shown by a thin line and the steering torque is shown by a thick line, but both are substantially overlapped. If there is no correction by the SAT information correction unit, the target steering torque is approximately 0 Nm, and the follow-up control is performed by the torsion angle control unit based on this, so that the steering torque is also approximately 0 Nm as a result.

Next, the simulation result when there is a SAT information correction unit is shown. A second-order bandpass filter having a center frequency of 5 Hz is used as a filter in the filter section, and the SAT value excited in the same manner as in the case of FIG. 19A is filtered to obtain the filtered SAT information. The torque signal Tref_d obtained by multiplying the steering torque sensitive gain, the vehicle speed sensitive gain, and the steering angle sensitive gain is shown in FIG. 20 (A) together with the SAT value (the thick line is the torque signal Tref_d and the thin line is the SAT value). FIG. 20B shows changes in the target steering torque and the actual steering torque in this case. The parameters of the horizontal axis and the vertical axis in FIG. 20 are the same as those in FIG.

Also in FIG. 20B, the target steering torque is shown by a thin line and the steering torque is shown by a thick line, but both are almost overlapped. Comparing the SAT value (thin line) in FIG. 20 (A) with the steering torque in FIG. 20 (B), it can be seen that the steering torque follows the target SAT value. That is, the SAT value near 5 Hz (around 4 to 5 seconds in time) can be realized as the steering torque.

In the simulation, a second-order bandpass filter was used as the filter of the filter unit, but the order is not limited to the second order, and a filter of another order may be used.

In the filter unit 252 in the SAT information correction unit 250 in the first embodiment, the filter processing is performed by one filter, but when there is a plurality of information to be transmitted to the driver and the band in which the information exists is different, etc. Then, a plurality of filters having each band as a pass band may be connected in parallel to perform the filter processing. For example, when there are three pieces of information to be transmitted, the filter unit may be configured by connecting the three filters in parallel as in the configuration example (second embodiment) shown in FIG. _{In this case, the SAT value T SAT} is input to the filters 652A, 652B and 652C in the filter unit 652, the output from each filter is added by the addition unit 652D, and the SAT information T _ST 1 is output. The number of filters to be connected can be arbitrarily selected according to the number of information to be transmitted and the like.

The target steering torque generation unit 200 in the first embodiment includes a basic map unit 210, a damper calculation unit (damper gain unit 230 and multiplication unit 260), a hysteresis correction unit 240, and a SAT information correction unit 250, but is related to SAT. A configuration may be configured in which only the SAT information correction unit 250 is provided, specializing only in the processing to be performed. FIG. 22 shows a configuration example (third embodiment) of the target steering torque generating unit in this case. In the target steering torque generation unit 700, the torque signal Tref_d output from the SAT information correction unit 250 is output as the target steering torque Tref. The target steering torque generation unit may be configured by combining at least one of the basic map unit 210, the damper calculation unit and the hysteresis correction unit 240, and the SAT information correction unit 250.

The motor current command value Imc output from the torsion angle control unit in the first to third embodiments is referred to as a current command value calculated based on the steering torque in the conventional EPS (hereinafter, "assist current command value"). ) May be added, for example, to the current command value Iref1 output from the current command value calculation unit 31 shown in FIG. 2, or the current command value Iref2 obtained by adding the compensation signal CM to the current command value Iref1.

FIG. 23 shows a configuration example (fourth embodiment) to which the above contents are applied to the first embodiment. The assist control unit 800 includes a current command value calculation unit 31, a current command value calculation unit 31, a compensation signal generation unit 34, and an addition unit 32A. The assist current command value Iac output from the assist control unit 800 (corresponding to the current command value Iref1 or Iref2 in FIG. 2) and the motor current command value Imcc output from the twist angle control unit 300 are added by the addition unit 810. The current command value Ic, which is the result of addition, is input to the current limiting unit 820, and the motor is driven based on the current command value Icm in which the maximum current is limited, and current control is performed. The current command value Icm is input to the target steering torque generation unit 200 instead of the motor current command value Imcc, and is used for estimating the _{SAT value T SAT by the SAT estimation unit 251 in the SAT information correction unit 250.} The motor current detection value may be used instead of the current command value Icm.

In the target steering torque generation unit 200 including the basic map unit 210 in the first to fourth embodiments, the phase compensation unit 270 that performs phase compensation may be inserted in the front stage or the rear stage of the basic map unit 210. That is, the configuration of the region R surrounded by the broken line in FIG. 5 may be configured as shown in FIGS. 24A or 24B. In the phase compensation unit 270, when phase advance compensation is set as phase compensation and, for example, phase advance compensation is performed by a primary filter in which the cutoff frequency of the numerator is 1.0 Hz and the cutoff frequency of the denominator is 1.3 Hz. A refreshing feel can be achieved. The target steering torque generating unit is not limited to the above configuration as long as it has a configuration based on the steering angle.

Further, if the EPS control system is stable, the stabilization compensation unit may be omitted. The output limiting unit can also be omitted.

Although the present invention is applied to the column type EPS in FIGS. 1 and 3, the present invention is not limited to the upstream type such as the column type, and can be applied to the downstream type EPS such as the rack and pinion. Further, by performing feedback control based on the target torsion angle, it can be applied to a steering bar (SBW) reaction force device having at least a torsion bar (arbitrary spring constant) and a sensor for detecting the torsion angle. An embodiment (fifth embodiment) when the present invention is applied to an SBW reaction force device provided with a torsion bar will be described.

First, the entire SBW system including the SBW reaction force device will be described. FIG. 25 is a diagram showing a configuration example of the SBW system corresponding to the general configuration of the electric power steering device shown in FIG. The same components are designated by the same reference numerals, and detailed description thereof will be omitted.

The SBW system is a system that does not have an intermediate shaft that is mechanically coupled to the column shaft 2 by a universal joint 4a, and transmits the operation of the steering wheel 1 to a steering mechanism consisting of steering wheels 8L, 8R, etc. by an electric signal. .. As shown in FIG. 25, the SBW system includes a reaction force device 60 and a drive device 70, and a control unit (ECU) 50 controls both devices. The reaction force device 60 detects the steering angle θh by the steering angle sensor 14, and at the same time, transmits the motion state of the vehicle transmitted from the steering wheels 8L and 8R to the driver as a reaction force torque. The reaction force torque is generated by the reaction force motor 61. Although some SBW systems do not have a torsion bar in the reaction force device, the SBW system to which the present invention is applied is a type that has a torsion bar, and the torque sensor 10 detects the steering torque Ts. To do. Further, the angle sensor 74 detects the motor angle θm of the reaction force motor 61. The drive device 70 drives the drive motor 71 in accordance with the steering of the steering wheel 1 by the driver, applies the driving force to the pinion rack mechanism 5 via the gear 72, and operates the tie rods 6a and 6b. Steer the facing wheels 8L and 8R. An angle sensor 73 is arranged in the vicinity of the pinion rack mechanism 5 to detect the steering angle θt of the steering wheels 8L and 8R. In order to coordinately control the reaction force device 60 and the drive device 70, the ECU 50 adds information such as the steering angle θh and the steering angle θt output from both devices, and based on the vehicle speed Vs from the vehicle speed sensor 12 and the like. The voltage control command value Vref1 for driving and controlling the reaction force motor 61 and the voltage control command value Vref2 for driving and controlling the driving motor 71 are generated.

The configuration of the fifth embodiment to which the present invention is applied to such an SBW system will be described.

FIG. 26 is a block diagram showing the configuration of the fifth embodiment. In the fifth embodiment, the reaction force device is twisted by controlling the twist angle Δθ (hereinafter referred to as “twist angle control”) and controlling the steering angle θt (hereinafter referred to as “turning angle control”). It is controlled by angle control, and the drive unit is controlled by steering angle control. The drive device may be controlled by another control method.

In the twist angle control, the twist angle Δθ follows the target twist angle Δθref calculated through the target steering torque generation unit 200 and the conversion unit 500 using the steering angle θh and the like by the same configuration and operation as in the first embodiment. However, the target steering torque generation unit 200 has a motor current command value Imct calculated by the steering angle control unit 920 instead of the motor current command value Imct calculated by the twist angle control unit 300. It is input, and the steering angle θt is input instead of the motor angle θm. The motor angle θm is detected by the angle sensor 74, and the motor angular velocity ωm is calculated by differentiating the motor angle θm by the angular velocity calculation unit 951. The steering angle θt is detected by the angle sensor 73. The SAT information correction unit 250 in the target steering torque generation unit 200 can estimate the SAT by regarding the drive device as one inertia (or mass). That is, by using the steered angle θt instead of the motor angular .theta.m, column shaft in terms of inertia J, the static friction Fr and the damper coefficient D _M as parameters to match the drive, since the drive is not present the torsion bar , SAT is estimated by setting the steering torque Ts to 0. Further, although the processing in the EPS steering system / vehicle system 100 is not described in detail in the first embodiment, the current control unit 130 includes the subtraction unit 32B, the PI control unit 35, and the PWM control shown in FIG. With the same configuration and operation as the unit 36 and the inverter 37, based on the motor current command value Imc output from the torsion angle control unit 300 and the current value Imr of the reaction force motor 61 detected by the motor current detector 140. The reaction force motor 61 is driven to control the current.

In the steering angle control, the target steering angle generation unit 910 generates a target steering angle θtref based on the steering angle θh, and the target steering angle θtref is input to the steering angle control unit 920 together with the steering angle θt. The steering angle control unit 920 calculates the motor current command value Imct so that the steering angle θt becomes the target steering angle θtref. Then, based on the motor current command value Imct and the current value Imd of the drive motor 71 detected by the motor current detector 940, the current control unit 930 has the same configuration and operation as the current control unit 130, and the drive motor has the same configuration and operation. The 71 is driven to control the current.

FIG. 27 shows a configuration example of the target steering angle generation unit 910. The target steering angle generation unit 910 includes a limiting unit 931, a rate limiting unit 932, and a correction unit 933.

The limiting unit 931 limits the upper and lower limits of the steering angle θh and outputs the steering angle θh1. Similar to the limiting unit 256 in the SAT information correction unit 250 and the output limiting unit 350 in the torsion angle control unit 300, the upper limit value and the lower limit value with respect to the steering angle θh are set in advance to limit.

The rate limiting unit 932 sets and limits the amount of change in the steering angle θh1 in order to avoid a sudden change in the steering angle, and outputs the steering angle θh2. For example, the difference from the steering angle θh1 one sample before is used as the change amount, and when the absolute value of the change amount is larger than a predetermined value (limit value), the steering angle is set so that the absolute value of the change amount becomes the limit value. θh1 is added or subtracted and output as the steering angle θh2, and if it is equal to or less than the limit value, the steering angle θh1 is output as it is as the steering angle θh2. Instead of setting a limit value for the absolute value of the amount of change, an upper limit value and a lower limit value may be set for the amount of change to limit the amount of change. You may want to limit the rate.

The correction unit 933 corrects the steering angle θh2 and outputs the target steering angle θtref. For example, a map that defines the characteristics of the target steering angle θtref with respect to the magnitude | θh2 | of the steering angle θh2, such as the basic map unit 210 in the target steering torque generation unit 200, is used to steer the target from the steering angle θh2. Find the angle θtref. Alternatively, the target steering angle θtref may be obtained by simply multiplying the steering angle θh2 by a predetermined gain.

FIG. 28 shows a configuration example of the steering angle control unit 920. The steering angle control unit 920 has the same configuration as the configuration example of the torsion angle control unit 300 shown in FIG. 15 except for the stabilization compensation unit 340 and the addition unit 362, and has a target torsion angle Δθref and a torsion. The target steering angle θtref and steering angle θt are input instead of the angle Δθ, and the steering angle feedback (FB) compensation unit 921, the steering angular velocity calculation unit 922, the speed control unit 923, the output limiting unit 926 and the subtraction unit 927 are input. However, the same operation is performed with the same configurations as the torsion angle FB compensation unit 310, the torsion angular velocity calculation unit 320, the speed control unit 330, the output limiting unit 350, and the subtraction unit 361, respectively.

In such a configuration, an operation example of the fifth embodiment will be described with reference to the flowchart of FIG.

When the operation is started, the angle sensor 73 detects the steering angle θt, the angle sensor 74 detects the motor angle θm (step S110), and the steering angle θt is the target steering torque generating unit 200 and the steering angle control unit 920. The motor angle θm is input to the angular velocity calculation unit 951 respectively.

The angular velocity calculation unit 951 differentiates the motor angle θm to calculate the motor angular velocity ωm, and outputs the motor angular velocity to the right / left turn determination unit 400 and the torsion angle control unit 300 (step S120).

After that, in the target steering torque generator 200, the motor current command value Imct is used instead of the motor current command value Imcc, and the steering angle θt is used instead of the motor angle θm, as in steps S10 to S60 shown in FIG. Is executed, the reaction force motor 61 is driven, and current control is performed (steps S130 to S170).

On the other hand, in the steering angle control, the target steering angle generation unit 910 inputs the steering angle θh, and the steering angle θh is input to the limiting unit 931. The limiting unit 931 limits the upper and lower limit values of the steering angle θh by preset upper and lower limit values (step S180), and outputs the steering angle θh1 to the rate limiting unit 932. The rate limiting unit 932 limits the amount of change in the steering angle θh1 by a preset limit value (step S190), and outputs the steering angle θh2 to the correction unit 933. The correction unit 933 corrects the steering angle θh2 to obtain the target steering angle θtref (step S200), and outputs the steering angle θh2 to the steering angle control unit 920.

The steering angle control unit 920, which has input the steering angle θt and the target steering angle θtref _{, calculates the deviation Δθt 0} by subtracting the steering angle θt from the target steering angle θtref by the subtracting unit 927 (step). S210). Deviation Derutashitati ₀ is input to the turning angle FB compensation unit 921, the turning angle FB compensation unit 921 compensates the deviation Derutashitati ₀ by multiplying the compensation value to the deviation Δθt ₀ (step S220), the target turning angular velocity The ω tref is output to the speed control unit 923. The steering angular velocity calculation unit 922 inputs the steering angle θt, calculates the steering angular velocity ωtt by a differential calculation with respect to the steering angle θt (step S230), and outputs the steering angular velocity ωtt to the speed control unit 923. The speed control unit 923 calculates the motor current command value Imcta by IP control in the same manner as the speed control unit 330 (step S240), and outputs the motor current command value Imcta to the output limiting unit 926. The output limiting unit 926 limits the upper and lower limit values of the motor current command value Imcta by the preset upper limit value and lower limit value (step S250), and outputs the motor current command value Imct as the motor current command value Imct (step S260).

The motor current command value Imct is input to the target steering torque generation unit 200 and is input to the current control unit 930, and the current control unit 930 is the drive motor detected by the motor current command value Imct and the motor current detector 940. Based on the current value Imd of 71, the drive motor 71 is driven to perform current control (step S270).

The order of data input and calculation in FIG. 29 can be changed as appropriate. Further, the speed control unit 923 in the steering angle control unit 920 is not the IP control but the PI control, the P control, the PID control, and the PI-D, like the speed control unit 330 in the twist angle control unit 300. Control and the like are feasible, and any of P, I, and D controls may be used, and follow-up control by the steering angle control unit 920 and the twist angle control unit 300 is generally used. The control structure may be used.

In the fifth embodiment, as shown in FIG. 25, one ECU 50 controls the reaction force device 60 and the drive device 70, but the ECU for the reaction force device 60 and the ECU for the drive device 70 are used, respectively. It may be provided. In this case, the ECUs transmit and receive data by communication. Further, the SBW system shown in FIG. 25 does not have a mechanical coupling between the reaction force device 60 and the drive device 70, but when an abnormality occurs in the system, the column shaft 2 and the steering mechanism are clutched or the like. The present invention is also applicable to SBW systems provided with a mechanical torque transmission mechanism that mechanically couples with. In such an SBW system, when the system is normal, the clutch is turned off to open the mechanical torque transmission, and when the system is abnormal, the clutch is turned on to enable the mechanical torque transmission.

The twist angle control unit 300 in the first to fifth embodiments and the assist control unit 800 in the fourth embodiment directly calculate the motor current command value Imc and the assist current command value Iac. Before calculating them, the motor torque (target torque) to be output may be calculated first, and then the motor current command value and the assist current command value may be calculated. In this case, in order to obtain the motor current command value and the assist current command value from the motor torque, the generally used relationship between the motor current and the motor torque is used.

1 Handle 2 Column shaft (steering shaft, handle shaft)
2A Torsion bar 3 Deceleration mechanism 10 Torque sensor 12 Vehicle speed sensor 14 Steering angle sensor 20 Motor 30, 50 Control unit (ECU)
31 Current command value calculation unit 33, 820 Current limit unit 34 Compensation signal generation unit 38, 140, 940 Motor current detector 60 Reaction force device 61 Reaction force motor 70 Drive device 71 Drive device 71 Drive motor 72 Gear 73, 74 Angle sensor 100 EPS Steering system / Vehicle system 130, 930 Current control unit 200, 700 Target steering torque generation unit 210 Basic map unit 211 Code unit 230 Damper gain unit 240 Hysteresis correction unit 250 SAT information correction unit 251 SAT estimation unit 251A Conversion unit 251B, 951 Angle speed Calculation unit 251C Angle acceleration calculation unit 252, 652 Filter unit 253 Steering torque sensitive gain unit 254 Vehicle speed sensitive gain unit 255 Steering angle sensitive gain unit 256, 931 Limiting unit 270 Phase compensation unit 300 Twist angle control unit 310 Twist angle feedback (FB) Compensation unit 320 Twist angle Speed calculation unit 330, 923 Speed control unit 340 Stabilization compensation unit 350, 926 Output limit unit 400 Right turn / left turn judgment unit 500 Conversion unit 800 Assist control unit 910 Target steering angle generation unit 920 Steering angle Control unit 921 Steering angle feedback (FB) Compensation unit 922 Steering angle Speed calculation unit 932 Rate limiting unit 933 Correction unit

Claims (11)

In a vehicle steering device that includes at least a torsion bar having an arbitrary spring constant and a sensor that detects the torsion angle of the torsion bar, and assists and controls the steering system by driving and controlling the motor.
A target steering torque generator that generates a target steering torque, and a target steering torque generator
A conversion unit that converts the target steering torque into a target torsion angle, and
It is provided with a twist angle control unit that calculates a motor current command value that causes the twist angle to follow the target twist angle.
The target steering torque generator
A SAT information correction unit that calculates a first torque signal based on a self-aligning torque value is provided, and the first torque signal is output as the target steering torque.
The SAT information correction unit
A SAT estimation unit that estimates the self-aligning torque value based on the steering torque, angle information, and the motor current command value.
It is provided with a filter unit that performs a filter process on the self-aligning torque value and calculates the first torque signal.
A vehicle steering device characterized in that the motor is driven and controlled based on the motor current command value. The vehicle steering device according to claim 1, wherein the filter unit is composed of one filter or a plurality of filters connected in parallel. The SAT information correction unit
The vehicle steering device according to claim 1 or 2, further comprising a steering torque-sensitive gain unit that multiplies the first torque signal by the steering torque-sensitive gain. The vehicle steering device according to claim 3, wherein the steering torque sensitive gain is set to be large on-center. The SAT information correction unit
The vehicle steering device according to any one of claims 1 to 4, further comprising a vehicle speed-sensitive gain unit that multiplies the first torque signal by the vehicle speed-sensitive gain. The vehicle steering device according to claim 5, wherein the vehicle speed-sensitive gain is set to be large at high speed. The SAT information correction unit
The vehicle steering device according to any one of claims 1 to 6, further comprising a steering angle sensitive gain unit that multiplies the first torque signal by the steering angle sensitive gain. The SAT information correction unit
The vehicle steering device according to any one of claims 1 to 7, further comprising a limiting unit that limits the upper and lower limits of the first torque signal. The target steering torque generator
The basic map section that obtains the second torque signal from the steering angle and vehicle speed using the basic map,
A damper calculation unit that obtains a third torque signal based on angular velocity information using a damper gain map that is sensitive to vehicle speed,
A hysteresis correction unit for obtaining a fourth torque signal by performing hysteresis correction using the steering state and the steering angle is further provided.
The vehicle according to any one of claims 1 to 8, wherein the target steering torque is calculated from the second torque signal, the third torque signal, at least one of the fourth torque signals, and the first torque signal. Steering device. The vehicle steering device according to claim 9, wherein the characteristics of the basic map and the hysteresis correction unit are vehicle speed sensitivity. The target steering torque generator
A phase compensation unit that performs phase compensation is further provided in the front stage or the rear stage of the basic map unit.
The vehicle steering device according to claim 9 or 10, wherein the second torque signal is obtained from the steering angle and the vehicle speed via the basic map unit and the phase compensation unit.

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