JP2003285758A - Electric steering controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent change of viscosity coefficient to an abnormal value when steering angle is small and steering speed is high. <P>SOLUTION: A block diagram shows processing contents of an assist control part 20. An EPS full action force calculation part 3001 calculates an EPS full action force based on a pinion rotation angle θ<SB>p</SB>and angular velocity ω<SB>p</SB>. A rack thrust calculation part 3002 calculates a rack thrust based on a pinion torque T<SB>p</SB>and a motor torque T<SB>m</SB>. A disturbance torque calculation part 3003 calculates a disturbance torque T<SB>d</SB>based on a difference between the EPS full action force and the rack thrust. A side slip angle calculation part 3004 calculates a side slip angle α<SB>f</SB>based on the pinion rotation angle θ<SB>p</SB>and a car speed u. A SAT/internal resistance calculation part 3005 estimates gradient κand viscosity coefficient ρ based on the pinion angular velocity ω<SB>p</SB>, the side slip angle α<SB>f</SB>, and the disturbance torque T<SB>d</SB>. At this time, the estimated gradient κand viscosity coefficient ρ are not updated while the steering cycle is shorter than a predetermined value. The viscosity coefficient ρ is read out for control by an assist torque calculation part 3006. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a vehicle steering system.
And in particular its control. [0002] 2. Description of the Related Art Applicants have filed Japanese Patent Application No. 2000-37070.
At 4, self-alignment input to the wheels from the road surface
External force due to torque (hereinafter abbreviated as SAT) and motor
Internal drag (cohesive friction) due to Coulomb friction and viscous friction inside the device
The disturbance torque T _dCalculated as
SAT's front wheel sideslip angle α_fAnd the viscosity κ
Torque and steering speed ω_pThe viscosity coefficient ρ as the ratio of
Then, while updating the estimated viscosity coefficient ρ,
Of a steering device that controls the amount of steering assist torque
Application for control equipment. [0003] This technique employs an earlier viscosity coefficient ρ
To control the amount of steering assist torque with a constant value
In the control device of the steering system, internal drag (viscous torque) is generated.
It can respond to individual vehicles due to annual changes and variations between vehicles
It was made to solve problems such as
You. [0004] SUMMARY OF THE INVENTION
According to this, when steering with a small steering angle and a high steering speed is performed,
The estimation of the sex coefficient ρ is not performed normally, and the accuracy of the estimated value is sharp.
The problem remained worse. Therefore, the present invention
SAT front wheel sideslip angle α_fAnd the viscosity κ
Look and steering speed ω_pThe viscosity coefficient ρ as the ratio of
Therefore, when using the estimated viscosity coefficient ρ, the steering angle is small.
Even when the steering speed is high, the viscosity coefficient ρ
The purpose is to ensure that the estimates do not take outliers. [0005] Means for Solving the Problems To solve the above problems,
According to the first aspect, the electric motor assists
Electric steering control device that applies torque
The viscosity of the steering system that gives a reaction force depending on the steering angular velocity.
The viscosity to estimate the viscosity coefficient related value, which is a physical quantity related to numbers
Sex coefficient related value estimating means and steering cycle for detecting steering cycle
Detecting means, and a steering circumference detected by the steering cycle detecting means.
If the period is shorter than the predetermined value, the viscosity coefficient
Do not estimate the viscosity coefficient related value by the continuous value estimation means.
Before the steering cycle enters a period shorter than the predetermined value.
Correction of the determined viscosity coefficient related value as the estimated value at the current time
Means, the viscosity coefficient related value estimating means and the correcting means.
The assist torque is controlled based on the specified viscosity coefficient related value.
And an assist torque control means for controlling
I do. [0006] [Operation and Effect of the Invention] The steering angle is small and the steering speed is fast.
When steering is performed, the steering cycle becomes shorter. There
When the steering cycle is shorter than the specified value,
The previously estimated normal viscosity coefficient-related values are estimated at the current time.
If it is a constant value, the viscosity coefficient related value will not indicate an abnormal value.
It becomes. As a result, the steering angle is small and the steering speed is fast.
Even when the rudder is operated, a highly accurate viscosity coefficient related value
It can be estimated and assist torque control is performed reliably. [0007] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to specific examples.
It will be described based on the following. However, the present invention is not limited to the following embodiments.
However, the present invention is not limited to this. FIG. 1 shows an electric power according to an embodiment of the present invention.
FIG. 2 is a hardware configuration diagram of the steering device 100.
You. Hereinafter, the electric power steering apparatus 10 of the present embodiment
0 will be described. One end of the steering shaft 10 is
The tearing wheel 11 (handle) is attached,
The other end has a pinion shaft 13 that is mounted on a gear box 12.
Are combined. The pinion shaft 13 is mounted on the gearbox 1
2 is engaged with the rack shaft 14 fitted in
No, but both ends of this rack shaft 14 are ball joints
Are connected to steering wheels (not shown). Also,
An assist torque is applied to the tearing shaft 10.
Brushless DC motor M (hereinafter simply referred to as “motor M”)
) Are connected via two gears 17. The motor M includes a motor control device 200
From the driving circuit 213 via the current detector 215.
Motor drive currents iu, iv, i for the three phases V, W
w is supplied. Furthermore, the steering shaft 10
Is the steering wheel (handle) 11 from the driver.
Magnitude and direction of the manual steering force applied to the vehicle
The torque detector 15 for detecting (steering torque T)
Is provided. The rotation angle of the motor M is detected.
A rotation angle sensor E (encoder) for synchronization
And the rotation angle θ of the motor M output by the rotation angle sensor E_m
Rotation angle (= steering angle of steering wheel) θ based on_p
Is required. The motor control device 200 includes a CPU 21
0, ROM 211, RAM 212, drive circuit 213, input
Force interface (IF) 214, current detector 215
And so on. The drive circuit 213 includes an unillustrated battery.
Terry, PWM converter, PMOS drive circuit, etc.
The drive current is changed to a sine wave by chopper control,
Supply power to M. The CPU 210 of the motor control device 200
Is the rotation angle θ_mUsed for detecting the steering torque T
Torque sensor 15, vehicle speed meter 50 that gives vehicle speed V, etc.
These output signals (measured values) are applied to the input interface (I
F) Input via 214. The CPU 210
Based on a predetermined torque calculation from these input values, the motor M
Output torque value (command torque T_m) And update
In addition, this command torque T_mD-axis and q-axis currents based on
Command value (Id^*, Iq^*). However, this embodiment
In "Id^*= 0 ”. FIG. 2 shows an electric power unit according to this embodiment.
The control block of the motor control device 200 of the tearing device 100
This is a lock diagram. Input / output of each control block
Is as follows. The torque sensor 15 is
The torque is output to the phase compensator 21 and the differential calculator 23. Rank
The phase compensator 21 assist-controls the phase-compensated steering torque.
Output to the control unit 20. The differential operation unit 23 calculates the fine steering torque.
The output is output to the inertial compensation unit 22. The speedometer 50 shows the vehicle speed.
Cyst control unit 20, damper control unit 24, handle return control
Output to the control unit 26. Relative angle calculation from motor
Output to the section 60, the relative angle of the steering angle is calculated, and the differential operation is performed.
It is output to the calculating unit 61. The differential operation unit 61 calculates the angular velocity of the steering angle.
The degree is output to the damper control unit 24 and the handle return control unit 26
I do. Assist control unit 20, inertia control unit 22, damper control
The control unit 24 and the handle return control unit 26
The torque is output according to the set formula. In addition, reed
In the strike control unit 20, the viscosity coefficient is determined by a method described later.
ρ_hIs estimated, and the assist torque is determined using the estimated value.
Torque output by assist control unit 20 and inertia control unit 22
Is the same direction as the steering speed, the damper control unit 24 and the steering wheel return
The torque output from the control unit 26 is in the direction opposite to the steering speed.
You. Assist control unit 20, inertia control unit 22, damper control
Unit 24, the output of the handle return control unit 26
And the motor torque T_mCurrent command calculation unit 3
Output to 0. From the current command calculation unit 30 to the current control unit
40, the q-axis current command value (Iq^*) Is output and the motor
Supplied to the motor M as drive currents iu, iv, iw
You. FIG. 3 shows the assist control unit 20 of this embodiment.
FIG. 4 is a block diagram illustrating processing contents. EPS total acting force calculation
In the part 3001, the pinion rotation angle θ_pAnd angular velocity ω_pFrom
Calculate the EPS total acting force. Rack thrust calculator 3002
Then, the pinion torque T_PAnd motor torque T_mFrom rack
Calculate thrust. In the disturbance torque calculation unit 3003, the EPS
From the difference between the total acting force and the rack thrust, the disturbance torque T_dCalculate
You. On the other hand, the side slip angle calculation unit 3004 calculates the pinion rotation angle
Degree θ_pFrom the vehicle speed u and the sideslip angle α_fIs calculated. SAT /
The internal drag calculator 3005 calculates the pinion angular velocity ω_pAnd the side
Slip angle α_fAnd disturbance torque T_dFrom the slope κ and viscosity coefficient ρ
Is estimated. Estimated by SAT / internal drag calculator 3005
The slope κ and viscosity coefficient ρ are updated while the viscosity coefficient ρ
Is read for control by the assist torque calculation unit 3006.
Will be issued. T_pIs the steering torque of the driver, ω_pIs a pinion
Angular velocity (= dθ_p/ Dt) and the pinion rotation angle θ_pIs
θ_p= Θ_S−T_p/ K_SIs required. Where θ_SIs steering
The steering angle detected by the angle sensor,_SIs the steering
・ Spring setting indicating the torsional rigidity of the shaft torsion bar
Is a number. Also, the spring constant K_SIs very large
Has θ_p≒ θ_SIt is safe to consider that
Under various preconditions, distinguish pinion angle and steering angle.
May be discussed without notice. The torque (self-alignment) caused by the road surface reaction force
Ning torque T_S) Is the equation of motion of the steering system (the following equation)
Based on (1)), it can be expressed as in equation (2).
You. (Equation 1)   J_e・ Dω_p/ Dt = T_p+ GT_m+ T_S−ρω_p≡d… (1) (Equation 2)   T_S−ρω_p= D-T_p-GT_m                            … (2) Here, J_eIs the rotational motion of the steering system
Total inertia (inertia) for T_mIs the output of the motor 34
Force torque (auxiliary torque), g is the gear ratio of the reducer, ρ is
Pinion angular velocity ω of viscous torque that resists rotation of the handle_p
And d is the total torque acting on the steering system.
You. T_p, Ω_pIs calculated based on the output value of each sensor.
And the output torque T of the motor E_mIs
Estimate at any time based on the current value supplied to the motor E.
Can be. As for the total torque d in the equation (1), a well-known
Based on the control theory of feedback control, the equation of FIG.
Configuring the observer (state estimator) shown in (a)
Can be. Where G is the observer gain
(3 rows × 2 columns constant matrix), and d_hIs the total torque d
Estimated value, subscript h indicates that the variable is an estimated value
It is shown. Further, the above formula (a) is
If the discretization is performed at the sampling period Δt, the equation of FIG.
Obtain the discretized state equation as shown in (b) and (c).
Can be Here, A and C are constant matrices.
(3 rows × 3 columns), B and D are constant matrices (3 rows × 2 columns), x
Is a state vector representing the state of the steering system (3 rows x 1 column vertical vector).
And k is discretized by the sampling period Δt.
Time parameter (array argument). From the above, the discretized state shown in FIG.
Acts on the steering system based on the equations (Equations (b) and (c))
Estimated value d of the total torque d_hIf you can calculate accurately,
Disturbance torque T_S−ρω_pIs calculated more accurately from equation (2)
You can see what you can do. The above viscosity coefficient ρ changes with temperature.
Power steering systems
Fluctuates due to processing, adjustment, parts replacement, or specification change
In some cases. So, based on online least squares method
The viscosity coefficient ρ and the self-alignment
Ning torque T_SThe front wheel sideslip angle α_fGradient κ divided by
To estimate. [The front wheel sideslip angle α is obtained from the equation of motion._fPush
How to determine) The front wheel sideslip angle α of the vehicle_fIs the equation in FIG.
(D), approximation or
It is generally known that it can be estimated. Where
The subscript f indicates the front wheel, and the subscript r indicates the rear wheel.
Where ν [m / s] is the lateral velocity and r [rad / s]
Is yaw angular velocity, u [m / s] is vehicle speed, c_f[N / ra
d] is the cornering power of the front wheels, L_f[M] is a front wheel car
The distance between the shaft and the center of gravity of the vehicle, M [kg] is the vehicle mass, I
_z[Kg ・ m^Two] Is the moment of inertia about the z-axis of the vehicle, g
_hIs the handle angle (pinion angle θ_p) And the actual steering angle. Vehicle speed u and pinion angle θ_pWhen entering
At the sampling interval Δt, this equation of motion (the equation in FIG. 4)
(D), by discretizing equation (e), the following equation is obtained.
(3) and (4) are obtained. (Equation 3)   z (k + 1) = (I + Qu (k) + R / u (k)) z (k) + Sθ_p(k)… (3) (Equation 4)   α_f= (A / u (k), b / u (k)) z (k) -cθ_p(k)… (4) Here, k is a sampling period Δ
Time parameter similar to the second embodiment discretized by t
(Array argument), and z is a state vector representing the state of the vehicle body
(Vertical vector of 2 rows x 1 column), I is a unit of 2 rows x 2 columns
Matrix, Q is a constant matrix of 2 rows x 2 columns, S is a constant vector
(Vertical vector of 2 rows × 1 column). Also, in equation (4)
a, b, and c are constants, respectively. From the above, the figure
Front wheel sideslip angle α exemplified in FIG._fEstimation procedure (step 7
10 to step 780), the vehicle speed u and the pinion
Angle θ_pAt any time, the front wheel sideslip angle α_fGuess
It can be seen that the constant value can be obtained in real time. [Method of Estimating Viscosity Coefficient ρ] Next, d_h, Α_f
Is estimated on the basis of. d_h, Α_f, Ω_p,
T_p, T_m, G are obtained, and are determined by the following equation (5).
What is not shown is the gradient κ and the viscosity coefficient ρ. (Equation 5) κα_f−ρω_p= D-T_p-GT_m      … (5) Here, the on-line minimum for the equation (5)
By applying the square method, the gradient κ
And the viscosity coefficient ρ can be estimated at the same time. FIG.
Calculates the value of the viscosity coefficient ρ based on the online least squares method.
It is a flowchart of an estimation procedure to estimate. Book algorithm
First, in step 810, the forgetting factor
Initialize each component of the matrix L and the time parameter k.
You. λ₁, Λ_TwoOf the viscosity coefficient ρ and the slope κ
Considering the characteristics, for example, “λ₁= 0.999, λ_Two= 0.95 "
It should be set as follows. Next, at step 815, five algebras
Initialization of y, K, q, P, and φ is performed, respectively. However,
Here, y is a scalar, and K is a vertical vector of 2 rows × 1 column.
(State vector), q is a vertical vector of 2 rows x 1 column (viscosity
Estimated value vector composed of coefficient ρ and gradient κ), P is 2 rows ×
A variable matrix of two columns, φ is a vertical vector of 2 rows × 1 column, ρ
0 and κ0 are initial values of viscosity coefficient ρ and gradient κ (appropriate
Is a unit matrix of 2 rows × 2 columns, and c is an appropriate constant.
Is a number. In step 820, as shown, q
(k), y (k), φ (k), K (k)
Calculate the value. In step 830, as shown,
Calculate the value of P (k + 1) based on each value of L, P (k), φ (k)
I do. In step 840, the next step 850 is the cycle
Next execution of step 850 so that it is executed every Δt
Wait for the time. In step 850, the value of k is increased by one.
Let In step 860, α_f, D_h, Θ_p, T_p, T_m
Enter each value of. Where d_h, Α_fFor identification
Apply the already estimated values. In step 870, the input α_f, D_h,
θ_p, T_p, T_mAlgebra based on each value of
Update the values of φ and y, respectively. Where the algebra y (k)
Updating is performed based on equation (5), d = d_hAssuming that
Shall be executed. In step 880, P (k), φ
Update the value of algebra K (k) based on each value of (k) as shown
I do. In step 890, the estimated value of the viscosity coefficient ρ is
From the estimated value vector q (k) calculated in step 820 of
Ask. According to the above processing procedure, the viscosity coefficient ρ and the gradient κ
Can be calculated. This estimated viscosity
Coefficient ρ_hfar. Now, the steering angle is small and the steering speed is large.
In such a case, the estimated value of the viscosity coefficient becomes an abnormal value.
In such a case, it is important not to replace the viscosity coefficient with an abnormal value.
This is an example. This is the AT / internal drag calculation unit 300 in FIG.
5 has this function. [If the steering half cycle is 350 ms or less, the viscosity
Flowchart for not replacing numbers]
Operates according to the flowchart shown in FIG. In FIG.
Estimation of viscosity coefficient obtained by online least squares method
Value ρ_hSo that the steering half-cycle
Is set to NG depending on conditions. FIG.
By storing the previous steering angle on the chart,
Even if the steering does not pass through the neutral position of the steering wheel,
A change can be detected. First, at step 101, the
To perform high-pass filtering. Cutoff frequency
Is 2 Hz, for example. Next, in step 102, the high-pass
The sign of the steering wheel angle after filtering is determined. High pass
If the sign of the steering wheel angle after filtering is positive or 0,
The sign of the steering wheel angle after the high-pass filter
Is negative, the routine proceeds to step 203. In step 103, after the high-pass filter
The sign of the previous value of the steering wheel angle is determined. High passuff
If the sign of the previous value of the steering wheel angle after filtering is negative,
The top of the steering wheel angle after the high-pass filter
If the sign of the value is positive or 0, the process proceeds to step 107. In step 104, a half-cycle steering counter
Is below the minimum period for which the viscosity coefficient can be estimated.
Is determined. The steering half-period counter can estimate the viscosity coefficient.
If it is less than the low cycle, the process proceeds to step 105, and the steering half cycle
The counter must be below the minimum period for which the viscosity coefficient can be estimated.
If so, the process proceeds to step 106. In step 105, the steering half cycle flag is set.
Set to NG and proceed to step 106. Step 10
In step 6, the steering half cycle counter is cleared and step 11 is executed.
Go to 0. In step 107, a half-cycle steering counter
Is incremented and the routine proceeds to step 108. Steps
At 108, the steering half-cycle counter sets the maximum
It is determined whether the period is equal to or longer than the low cycle. Steering half cycle power
If the counter is longer than the minimum period
In step 109, the steering half-cycle counter sets the maximum
If it is less than the low cycle, the process proceeds to step 110. Step 1
In step 09, the steering half-cycle flag is set to OK and the
Proceed to step 110. In step 203, after the high-pass filter
The sign of the previous value of the steering wheel angle is determined. High passuff
If the sign of the previous value of the steering wheel angle after filtering is positive or 0
For example, in step 204, the steering wheel angle after the high-pass filter
If the sign of the previous value of is negative, the routine proceeds to step 207. In step 204, a steering half cycle counter
Is below the minimum period for which the viscosity coefficient can be estimated.
Is determined. The steering half-period counter can estimate the viscosity coefficient.
If the cycle is shorter than the low cycle, the routine proceeds to step 205, where the steering half cycle is set.
The counter must be below the minimum period for which the viscosity coefficient can be estimated.
If so, the process proceeds to step 206. In step 205, the steering half cycle flag is set.
Set to NG and proceed to step 206. Step 20
In step 6, the steering half cycle counter is cleared and step 11 is executed.
Go to 0. In step 207, a steering half cycle counter is set.
Is incremented and the routine proceeds to step 208. Steps
At 208, the steering half-cycle counter sets the maximum
It is determined whether the period is equal to or longer than the low cycle. Steering half cycle power
If the counter is longer than the minimum period
In step 209, the steering half-cycle counter detects
If it is less than the low cycle, the process proceeds to step 110. Step 2
In step 09, the steering half-cycle flag is set to OK and the
Proceed to step 110. In step 110, after the low-pass filter
The previous value of the steering wheel angle after the low-pass filter at the steering wheel angle of
And the steering wheel angle after the high-pass filter
Rewrite the previous value of the steering wheel angle after the
Return to step 101. FIG. 8 shows the viscosity when the input data is changed.
6 shows sex coefficient estimation data. FIG. 8 (a) shows a vehicle speed of 20 km / h.
Or 40km / h, steering speed 2rad / s or 4rad / s, steering angle 2
2.5 degrees, 45 degrees, 90 degrees, 180 degrees
It is. Steering speed was 4rad / s and steering angle was around 22.5 degrees
Irrespective of whether the vehicle speed is 20km / h or 40km / h
An abnormal value (negative value) was estimated as the viscosity coefficient. Also,
FIG. 8B shows a vehicle speed of 20 km / h or 40 km / h and a steering angle of ± 45.
Degrees or ± 90 degrees, steering speed around 0.5 rad / s, with 1 rad / s
Near, 2 rad / s, 4 rad / s, 8 rad / s
is there. When the steering speed is 8 rad / s and the steering angle is ± 45 degrees,
Regardless of whether the vehicle speed is 20km / h or 40km / h, the viscosity
An outlier (0 or negative value) was estimated as a number. The present invention
Now the viscosity coefficient cannot be replaced by these outliers
Can accurately estimate the viscosity coefficient.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hardware configuration diagram of an electric power steering device 100 according to an embodiment of the present invention. FIG. 2 is a control block diagram of a motor control device 200 of the electric power steering device 100. FIG. 3 is a block diagram showing a configuration of an assist control unit 20. FIG. 4 is a formula table of physical formulas related to the operation principle of the assist control unit 20. FIG. 5 is a flowchart showing the estimation procedure of the front wheel side slip angle alpha _f. FIG. 6 is a flowchart of an estimation procedure for estimating the value of the viscosity coefficient ρ based on the online least squares method. FIG. 7 is a flowchart for not replacing a viscosity coefficient when a half cycle of steering is 350 ms or less. FIG. 8A is a graph showing a time change of a vehicle speed and a steering angle as driving conditions for estimating a skid angle, and FIG.
FIG. 6 is a graph showing a time change of the sideslip angle estimated in the state of FIG. (Sum of the viscous torque and SAT) [sign Description of the θ _p ... pinion angle ω _p ... pinion angular velocity T _p ... the driver of the steering torque T _s ... self-aligning torque (SAT) T _d ... disturbance torque T _m ... motor Output torque (auxiliary torque) g ... gear ratio u ... vehicle speed J _e ... total inertia (inertia) related to rotational motion of the steering system d ... total torque d _h acting on the steering system ... estimated value h of total torque d ... subscript (Indicating that the variable is an estimated value) ρ: Viscosity coefficient α _f relating to the pinion angular velocity ω _p of viscous torque Front wheel side slip angle κ: Self-aligning torque gradient A to front wheel side slip angle α _f A: Constant Matrix (3 rows × 3 columns) B: Constant matrix (3 rows × 2 columns) C: Constant matrix (3 rows × 3 columns) D: Constant matrix (3 rows × 2 columns) G: Observer gain (3 rows × A two-column constant matrix) x ... State vector (vertical vector of 3 rows x 1 column) z ... State vector (vertical vector of 2 rows x 1 column) k ... Discrete time parameter (array argument) q (k) ... ρ corresponding to time t , Κ (vertical vector of 2 rows x 1 column) K (k) ... State vector (vertical vector of 2 rows x 1 column) P (k) ... Variable matrix (2 rows x 2 columns)

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) B62D 13:00 B62D 13:00 (72) Inventor Toshihiro Takahashi 1-1-1, Asahimachi, Kariya-shi, Aichi Pref. (72) Inventor Eiichi Ono 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-1 term in Toyota Central R & D Laboratories, Inc. (reference) 3D032 CC08 DA09 DA15 DA23 DA39 EB11 EC21 3D033 CA13 CA16 CA19

Claims (1)

Claims: 1. An electric steering control device in which an assist torque is applied by an electric motor, wherein a viscosity which is a physical quantity related to a viscosity coefficient of a steering system which gives a reaction force depending on a steering angular velocity. A viscosity coefficient related value estimating means for estimating a coefficient related value, a steering cycle detecting means for detecting a steering cycle, and a steering cycle detected by the steering cycle detecting means in a period shorter than a predetermined value. Correction means for estimating the viscosity coefficient-related value estimated before the steering cycle enters a period shorter than a predetermined value without estimating the viscosity coefficient-related value by the value estimating means; An assist torque control unit that controls the assist torque based on the viscosity-related value estimated by the coefficient-related value estimation unit and the correction unit. Electric steering control device according to claim.