JP2008162525A - Steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering control device capable of improving a steering feeling by taking vehicle response to an actual steering angle as a reaction torque into a steering system. <P>SOLUTION: This steering control device is mounted in a vehicle, and is favorably used for steering a steered wheel according to the operation of steering by controlling the drive of a motor for driving the steering of the steered wheel. In this device, a mathematical expression indicating the reaction torque to steering relative to the actual steering angle is Taylor-expanded, and taken into the steering system with 0-order, first-order, and second-order terms as equivalent rigidity, equivalent damping, and equivalent inertial moment, respectively, and thus, the steering control is executed. Since the reaction force is decided based on vehicle data, the dynamics of the steering system can be compensated appropriately. The steering feeling can be thus improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering control device that performs steering control.

  2. Description of the Related Art Conventionally, electric power steering (EPS) that assists a driver's steering with a driving force of a motor has been proposed. For example, in Patent Document 1, in order to reduce the uncomfortable feeling (inertia) at the time of steering, the elasticity in the rotational direction of the tire and the torsion bar has a reverse spring characteristic in a region where the frequency of the rotational direction handle position is a predetermined value or more. A power steering system is described.

Japanese Patent Laid-Open No. 2005-14850

  However, in the technique described in Patent Document 1 described above, the influence of changes in the vehicle specifications or the like on the dynamic characteristics of the steering system has not been considered. In addition, it has been difficult to appropriately compensate for changes in the vehicle specifications.

  The present invention has been made to solve the above-described problems, and a steering control device capable of improving a steering feeling by incorporating a vehicle response to an actual steering angle as a reaction torque into a steering system. The purpose is to provide.

  In one aspect of the present invention, a steering control device that steers a steered wheel according to a steering operation by performing drive control of a motor that steers the steered wheel to steer the steered wheel against an actual steered angle. Steering in which a mathematical expression indicating a force torque is developed in Taylor and steering control is performed by taking the zeroth order term of the formula obtained by the Taylor expansion as an equivalent stiffness, a first order term as an equivalent damping, and a second order term as an equivalent moment of inertia into the steering system. Control means are provided.

  The above-described steering control device is suitably used for turning a steered wheel in accordance with an operation of a steering (steering wheel) by performing drive control of a motor that is mounted on a vehicle and that steers the steered wheel. The This steering control device Taylor develops a mathematical expression showing the reaction torque to the steering with respect to the actual steering angle, and takes the zeroth term as equivalent stiffness, the first term as equivalent damping, and the second term as equivalent moment of inertia into the steering system. Steering control is performed with. Thereby, since the reaction force is determined based on the vehicle specifications, the dynamic characteristics of the steering system can be appropriately compensated. As a result, the steering feeling can be improved.

  In another aspect of the present invention, the steering control device that steers the steered wheels in accordance with the steering operation by performing drive control of the motor that steers the steered wheels drives the steered wheels with respect to the actual steered angle at the time of steady input. Decomposing the mathematical formula indicating the reaction torque to the steering into a real part and an imaginary part, and by applying the Taylor expansion of the real part, the zero-order term is equivalent stiffness, the quadratic term is equivalent moment of inertia, Steering control means for performing steering control by taking the imaginary part as equivalent damping into a steering system is provided.

  The steering control device described above is obtained by decomposing a mathematical expression indicating the reaction torque against the steering with respect to the actual steering angle at the time of steady input into a real part and an imaginary part, and by developing the real part by Taylor expansion. The next term is equivalent rigidity, the second term is equivalent moment of inertia, the imaginary part is taken as equivalent damping and steering control is performed. Also by this, since the reaction force is determined based on the vehicle specifications, the dynamic characteristics of the steering system can be appropriately compensated, and the steering feeling can be improved.

In one aspect of the steering control device, the steering control means includes
I _SW : Steering wheel inertia moment I _mt : Motor inertia moment C _SW : Steering system damping coefficient C _m : Motor damping control amount K _t : Torsion bar rigidity K _g : Motor assist T _SW : Input torque at steering wheel θ ₁ : Steering shaft rotation angle K _v : Equivalent rigidity I _v : Equivalent inertia moment C _v : Equivalent damping s: When Laplace operator is used, the following formula:
_{(K t K g I SW +} I mt + I V) θ 1 s 2 + (K t K g C SW + C m + C V) θ 1 s + K v θ 1 = K t K g T SW
Based on the above, the steering control can be executed.

  In another aspect of the above steering control device, the steering control means includes at least the vehicle speed, the vehicle mass, the longitudinal load distribution, and the equivalent rigidity, The steering control is performed so as to compensate for the equivalent damping and the equivalent moment of inertia. Thus, when the vehicle speed, the vehicle mass, the longitudinal load distribution, the dimensionless inertia moment, and the like change, it is possible to appropriately compensate the steering feeling.

  Preferably, in the steering control device, the steering control means can perform the steering control so that an attenuation ratio of the steering system is constant.

  Preferably, the steering control means performs the steering control so that the steering system has a damping ratio corresponding to at least the vehicle speed, the vehicle mass, the longitudinal load distribution, and the dimensionless inertia moment. It can be carried out.

  Preferably, the steering control means performs control to change at least one of assist, damping, and steering rigidity by the motor as the steering control.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

[overall structure]
First, the overall configuration of the steering control system 50 to which the steering control device according to the present embodiment is applied will be described. FIG. 1 is a schematic diagram showing the configuration of the steering control system 50.

  The steering control system 50 includes a steering wheel 1, a steering shaft 2, rotation angle sensors 3 and 6, a torsion bar 4, a motor 5, a speed reducer 5 a, a rack and pinion unit 7, and tie rods 8 r and 8 l. Knuckle arms 9r and 9l, wheels (front wheels) 10Fr and 10Fl, and a controller 20. In the following, “r” and “l” attached to the end of the reference numerals of the tie rods 8r and 8l, the knuckle arms 9r and 9l, and the wheels 10Fr and 10Fl will be omitted if they are used without distinction. And In this specification, the steering wheel is also simply referred to as “steering”.

  The steering control system 50 is configured by a so-called electric power steering (EPS) system. Specifically, the steering control system 50 steers the steered wheels according to the operation of the steering wheel 1 by performing drive control of the motor 5 that is mounted on the vehicle and steers the wheels 10F that are steered wheels. It is a system to let you.

  The steering wheel 1 is operated by the driver to turn the vehicle. The steering wheel 1 is connected to the rack and pinion unit 7 via the steering shaft 2. The steering shaft 2 is provided with rotation angle sensors 3 and 6, a torsion bar 4, and a speed reducer 5a. The torsion bar 4 is configured to be twisted with respect to the input from the steering wheel 1. The speed reducer 5 a is configured by a gear or the like, and is configured to receive power from the motor 5 and transmit the power to the steering shaft 2. The motor 5 is constituted by an electric motor or the like, and is controlled by a control signal supplied from the controller 20. For example, the motor 5 generates a steering assist force in accordance with the steering by the driver in order to assist the steering by the driver, and generates an additional damping force in order to improve the steering stability and the steering feeling. In the following, the torsion bar 4 is also referred to as “EPS torsion bar”, and the motor 5 is also referred to as “EPS motor”.

  The rotation angle sensor 3 detects a rotation angle corresponding to the operation of the steering wheel 1 by the driver. The rotation angle sensor 6 detects the rotation angle of the steering shaft 2 input to the rack and pinion unit 7. Detection signals corresponding to the rotation angles detected by these rotation angle sensors 3 and 6 are supplied to the controller 20.

  The rack and pinion unit 7 is configured by a rack, a pinion, or the like, and operates by transmitting rotation from the steering shaft 2. Further, a tie rod 8 and a knuckle arm 9 are connected to the rack and pinion unit 7, and a wheel 10 </ b> F is connected to the knuckle arm 9. In this case, when the tie rod 8 and the knuckle arm 9 are operated by the rack and pinion unit 7, the wheel 10F connected to the knuckle arm 9 is steered.

  The controller 20 includes a CPU, a ROM, a RAM, an A / D converter, and the like (not shown). The controller 20 corresponds to an ECU (Electronic Control Unit) in the vehicle. The controller 20 controls the motor 5 based on the rotation angle detected by the rotation angle sensors 3 and 6. In the present embodiment, the controller 20 takes in the vehicle response to the actual steering angle as a reaction force input (reaction force torque) to the steering system and performs control to compensate for the dynamic characteristics of the steering system. Specifically, the controller 20 sets the characteristics of the reaction torque to the steering wheel 1 with respect to the actual steering angle as equivalent rigidity, equivalent damping, and equivalent moment of inertia in the steering system, and reduces the steering feeling with respect to changes in vehicle characteristics. Control is performed to compensate for the steering feeling by capturing the change as a change to the steering system including equivalent stiffness, equivalent damping, and equivalent moment of inertia. That is, the controller 20 performs control so as to compensate for the equivalent rigidity, equivalent damping, and equivalent moment of inertia described above in order to suppress changes in steering feeling during vehicle control or control failure. In this case, the controller 20 performs control to change at least one of, for example, assist by the motor 5 (EPS assist), damping, and steering rigidity.

  As described above, the controller 20 corresponds to the steering control device in the present invention. Specifically, the controller 20 functions as steering control means in the present invention.

[Method of incorporating vehicle motion characteristics into the steering system]
Hereinafter, a method for incorporating the vehicle motion characteristics into the steering system will be specifically described.

(First method)
Here, a first method for incorporating vehicle motion characteristics into the steering system will be described. In the first method, a mathematical expression indicating a reaction torque to the steering wheel 1 with respect to an actual steering angle at the time of steady input (during steady excitation) is decomposed into a real part and an imaginary part, and the real part is developed in Taylor. The zeroth order term of the equation obtained by the above equation is taken as equivalent rigidity, the second order term is taken as the equivalent moment of inertia, and the imaginary part is taken into the steering system as equivalent damping (damping whose damping coefficient changes with frequency).

  The meanings of characters and symbols used in the following description are as follows.

m: Vehicle mass (kg)
I _Z : Yaw moment of inertia (kgm ² )
K _f , K _r : Front wheel and rear wheel equivalent CP (cornering power) (N / rad) (“K _f , K _r ” is the equivalent CP of the left and right wheels of the front wheel and the right and left wheels of the rear wheel (for two wheels) Equivalent CP)
β: Body slip angle (rad)
γ: Yaw rate (rad / s)
F _f , F _r : lateral force of front and rear wheels (N)
l _f : Distance from front wheel to center of gravity (m)
l _r : Distance from rear wheel to center of gravity (m)
δ: Wheel turning angle (rad)
ξ: Caster + Pneumatic trail (m)
N _S: vehicle speed (m / s)
I _SW : Steering wheel moment of inertia (kgm ² )
I _mt : EPS motor moment of inertia (kgm ² )
C _SW : Steering system damping coefficient (Nms / rad)
C _m : EPS (motor) damping control amount (Nms / rad)
F _S : Steering system friction (Nm)
K _t : EPS torsion bar rigidity (Nms / rad)
K _g : EPS assist T _SW : Input torque at steering wheel (Nm)
T _ms : Reaction torque (Nm) to steering system
θ ₀ : Steering wheel rotation angle (rad)
θ ₁ : Steering shaft rotation angle (rad)
K _v: equivalent stiffness I _v: equivalent inertia moment of C _v: Equivalent damping zeta _SW: attenuation ratio of the steering system s: Laplace operator I _Zn: dimensionless moment of inertia Figure 2 models the steering control system 50 described above A schematic diagram is shown. As shown in FIG. 2, the steering wheel 1 has a steering wheel inertia moment I _SW , a torsion bar 4 having EPS torsion bar rigidity K _t , and a motor having EPS damping control amount C _m and EPS motor inertia moment I _mt. 5 is provided on the steering shaft 2. Further, the steering system has a damping coefficient C _SW and the friction F _S works. In this case, the steering wheel 1 is rotated in the steering wheel rotational angle theta _0, the steering shaft 2 rotates at a steering shaft rotation angle theta _1. Further, the wheel 10F has a cutting angle δ, and a lateral force _Fr is applied. FIG. 2 also shows the reaction torque _Tms to the steering system.

FIG. 3 shows lateral forces F _f and F _r acting on the wheels 10F and 10R (front wheel 10F and rear wheel 10R). In this case, lateral forces F _f and F _r acting on the vehicle, which are the vehicle speed V, the vehicle body slip angle β, and the turning angle δ of the wheel 10F, are shown.

Hereinafter, how to obtain the above-described equivalent rigidity K _v , equivalent moment of inertia I _v , and equivalent damping C _v will be described.

  First, the vehicle model as shown in FIG. 2 described above can express exercise, balance, and the like by the following equations (1) to (6).

When the reaction force torque T _ms with respect to the input of the steering angle θ ₁ (corresponding to the actual steering angle) is obtained by solving the above expressions (1) to (6), the following expression (7) is obtained.

Here, the real part and the imaginary part in the reaction force torque T _ms can be expressed by considering “steady input (steady excitation)” and placing “s = jω”. Specifically, Expression (8) represents a real part (hereinafter, the real part is represented as “T _qRen ”), and Expression (9) represents an imaginary part (hereinafter, the imaginary part is represented as “T _qImn ”). .). Expression (10) represents a common denominator of the real part and the imaginary part (hereinafter, this denominator is represented as “den”).

Next, the real part T _qRen shown in Expression (8) is taken out and the following Expression (11) is defined.

  When the above equation (11) is Taylor-expanded with “ω = 0”, equation (12) is obtained.

In this case, “A ₀ ” that is the zero-order term in the equation (12) can be regarded as the equivalent stiffness K _v, and “A ₂ ” that is the quadratic term can be regarded as the equivalent moment of inertia I _v . Therefore, the equivalent stiffness _{K v} is obtained by the equation (13), the equivalent moment of inertia _{I v} is obtained by equation (14).

Note that the denominator of formula (14) (Deni _v) is represented by the formula (15), molecules (Numi _v) of formula (14) is expressed by Equation (16).

On the other hand, the equivalent attenuation (equivalent attenuation coefficient) C _v can be obtained from the imaginary part T _qImn shown in the above equation (9). Specifically, the equivalent damping _{C v} is obtained by the following equation (17).

Next, consider that the equivalent stiffness K _v , equivalent moment of inertia I _v , and equivalent damping C _v obtained as described above are taken into the steering system (that is, vehicle motion characteristics are taken into the steering system). First, it is assumed that the EPS compensation control and the response of the motor 5 are sufficiently higher than the vehicle response. If these are ignored, the simple steering system motion is described by the following equations (18) and (19). be able to.

Here, when the equivalent stiffness K _v , the equivalent moment of inertia I _v , and the equivalent damping C _v are substituted into the equation (19), the equation (20) is obtained.

Then, Equation (18) is solved by “K _t (θ ₀ −θ ₁ )”, and this is substituted into Equation (20). In this case, the rigidity of the steering system is sufficiently higher than the equivalent stiffness K _v, it can be placed as a "θ _{0 =} θ ₁ '. Thus, the following formula (21) is obtained.

Expression (21) represents an expression in which the equivalent stiffness K _v , equivalent moment of inertia I _v , and equivalent damping C _v from the vehicle response are taken into the steering system motion. That is, it represents a formula in which vehicle motion characteristics are taken into the steering system. The controller 20 described above performs steering control based on the equation (21).

  By incorporating the vehicle response to the actual steering angle as a reaction torque into the steering system as a reaction force input to the steering system by the first method described above, the dynamic characteristics of the steering system can be appropriately compensated. As a result, the steering feeling can be compensated and the steering feeling can be improved.

(Second method)
Next, a second method for incorporating vehicle motion characteristics into the steering system will be described. In the second method, a numerical expression indicating the reaction force torque to the steering wheel 1 with respect to the actual steering angle is Taylor-expanded, and the zero-order term of the expression obtained by this Taylor expansion is the equivalent stiffness _Kv , and the first-order term is the equivalent damping C _v and in that incorporated into the steering system of the second order term as an equivalent inertial moment I _v, different from the first method described above.

Specifically, in the second method, the reaction force torque _Tms expressed by the above-described equation (7) is directly developed by Taylor. In this case, when Taylor expansion is performed with “s = 0” and a quadratic term is taken, the following equation (22) is obtained.

Then, in the formula (22) obtained by Taylor expansion in the vicinity of "s = 0", the 0-order term and the equivalent stiffness K _v, the first-order terms and the equivalent damping C _v, the second-order terms equivalent moment of inertia I _v . In this case, the equivalent stiffness _Kv is expressed by the same formula as the above-described formula (13), and the equivalent inertia moment _Iv is expressed by the same formula as the above-described formula (14).

On the other hand, the equivalent damping C _v is represented by different formulas Formula (17) described above. Specifically, the equivalent damping C _v can be obtained by the following equation (23).

Even when the equivalent stiffness K _v , equivalent moment of inertia I _v , and equivalent damping C _v obtained in this way are taken into the motion of the steering system, they can be expressed by the aforementioned equation (21). Also in this case, the controller 20 described above executes the steering control based on the equation (21).

  By incorporating the vehicle response to the actual steering angle as reaction force torque into the steering system as a reaction force input to the steering system by the second method described above, the dynamic characteristics of the steering system can be appropriately compensated. As a result, the steering feeling can be compensated and the steering feeling can be improved.

[Steering feeling compensation method]
Next, a steering feeling compensation method according to this embodiment will be described. The controller 20 described above performs control so as to compensate for the equivalent rigidity, equivalent damping, and equivalent moment of inertia described above in order to suppress changes in steering feeling during vehicle control or control failure. That is, the controller 20 performs control for compensating for the steering feeling by capturing the change in the steering feeling with respect to the change in the vehicle characteristics as a change to the steering system including the equivalent stiffness, equivalent damping, and equivalent moment of inertia. Specifically, the controller 20 performs control to compensate for changes in steering feeling due to vehicle speed, vehicle mass, longitudinal load distribution, dimensionless inertia moment, and the like.

  Here, specific examples of changes in equivalent stiffness, equivalent damping, and equivalent moment of inertia due to changes in vehicle speed and vehicle specifications are shown in FIGS.

  FIG. 4 shows an example of changes in front wheel load distribution. 4 (a) to 4 (c) each show the vehicle speed (km / h) on the horizontal axis, the vertical axis in FIG. 4 (a) indicates equivalent rigidity, and the vertical axis in FIG. 4 (b) is equivalent. The attenuation is shown, and the vertical axis of FIG. 4C shows the equivalent moment of inertia. 4A to 4C, the results when the front wheel load distribution is “Dwf = 0.5”, “Dwf = 0.55”, and “Dwf = 0.6” are superimposed. it's shown. 4 (a) to 4 (c), it can be seen that the equivalent stiffness, equivalent damping, and equivalent moment of inertia change according to changes in the vehicle speed and the front wheel load distribution. It should be noted that the front wheel load distribution changes depending on the occupant and the load status of the luggage.

FIG. 5 shows an example of a change in the dimensionless inertia moment. The dimensionless inertia moment I _zn is defined by “I _zn = I _z / (l _f · l _r · m)”.

5A to 5C each show the vehicle speed (km / h) on the horizontal axis, the vertical axis of FIG. 5A shows equivalent rigidity, and the vertical axis of FIG. Attenuation is shown, and the vertical axis of FIG. 5C shows the equivalent moment of inertia. 5A to 5C, when the dimensionless inertia moment is “I _zn = 0.8”, “I _zn = 0.9”, and “I _zn = 1.1”. The results of are superimposed and displayed. From FIG. 5 (a), it can be seen that the equivalent stiffness changes only according to the vehicle speed and does not change depending on the non-dimensional inertia moment. On the other hand, it can be seen from FIGS. 5B and 5C that the equivalent damping and the equivalent moment of inertia change according to changes in the vehicle speed and the dimensionless inertia moment. The dimensionless inertia moment changes depending on the loading situation of the occupant and the luggage.

In the present embodiment, control is performed to compensate for the change in steering feeling caused by such vehicle speed, vehicle mass (loading condition and fuel consumption), longitudinal load distribution, non-dimensional inertia moment, and the like. Specifically, in order to compensate for the change in steering feeling, control is performed so that the damping ratio of the steering system is constant. That is, the damping ratio of the steering system is made constant regardless of the vehicle speed, the vehicle mass, the longitudinal load distribution, and the dimensionless inertia moment. In this case, the controller 20 performs control to change at least one of assist by the motor 5 (EPS assist), damping, and steering rigidity. Specifically, the controller 20, by performing control to change the like attenuation control amount C _m and EPS assist K _g of EPS, so that the damping ratio of the steering system is constant.

Here, the damping ratio of the steering system will be specifically described. First, from the above equation (21), the response of the steering angle (θ ₁ ) to the input of torque (T _SW ) can be expressed by the following equation (24).

Based on the above equation (24), the damping ratio ζ _SW of the steering system can be defined by equation (25).

The controller 20 controls the EPS damping control amount C in the equation (25) so that the steering system damping ratio ζ _SW is constant regardless of the vehicle speed, the vehicle mass, the longitudinal load distribution, the non-dimensional inertia moment, and the like. performs control to change the like _m and EPS assist _{K g.} Thereby, even when the vehicle speed, the vehicle mass, the longitudinal load distribution, the dimensionless inertia moment, and the like change, it is possible to appropriately compensate the steering feeling.

  In the above description, an example in which the steering system damping ratio is controlled to be constant has been described. However, the present invention is not limited to this. In another example, instead of making the damping ratio of the steering system constant, the control is performed so that the steering system has a damping ratio corresponding to the vehicle speed, vehicle mass, longitudinal load distribution, dimensionless inertia moment, etc. It can be carried out. Specifically, control can be performed as shown in the following (a) to (d).

  (A) In order to compensate for a change in steering feeling due to vehicle speed, control is performed so that the damping ratio of the steering system is low at low speeds, and control is performed so that the damping ratio of the steering system is high at high speeds.

  (B) In order to compensate for a change in steering feeling due to the vehicle mass, control is performed so that the damping ratio of the steering system increases as the vehicle mass increases.

  (C) In order to compensate for a change in steering feeling due to the distribution of front and rear loads, control is performed so that the damping ratio of the steering system increases as the load approaches the rear of the vehicle.

  (D) In order to compensate for the change in steering feeling due to the non-dimensional inertia moment, control is performed so that the damping ratio of the steering system increases as the non-dimensional inertia moment increases.

Also in these cases, the controller 20 performs control to change at least one of EPS assist, damping, and steering rigidity. Specifically, the controller 20 performs control to change the EPS attenuation control amount _Cm , the EPS assist _{Kg, and the} like. Thereby, even when the vehicle speed, the vehicle mass, the longitudinal load distribution, the dimensionless inertia moment, and the like change, it is possible to appropriately compensate the steering feeling.

It is the schematic which shows the structure of the steering control system which concerns on this embodiment. The schematic diagram which modeled the steering control system is shown. It is a figure which shows the lateral force etc. which act on the wheel at the time of turning. It is a figure which shows the example of a change of front wheel load distribution. It is a figure which shows the example of a change of a dimensionless inertia moment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3, 6 Rotation angle sensor 4 Torsion bar 5 Motor 5a Reduction gear 7 Rack and pinion part 8 Tie rod 9 Knuckle arm 10F Wheel (front wheel)
20 controller 50 steering control system

Claims (7)

In the steering control device that steers the steered wheels according to the steering operation by performing drive control of the motor that steers the steered wheels,
A formula that shows the reaction torque to the steering with respect to the actual steering angle is developed in Taylor, and the 0th order term of the formula obtained by the Taylor development is equivalent stiffness, the primary term is equivalent damping, and the secondary term is equivalent inertia moment. A steering control device comprising steering control means for taking in the system and performing steering control. In the steering control device that steers the steered wheels according to the steering operation by performing drive control of the motor that steers the steered wheels,
The mathematical expression indicating the reaction force torque to the steering with respect to the actual steering angle at the time of steady input is decomposed into a real part and an imaginary part, and the zeroth order term of the formula obtained by Taylor expansion of the real part is defined as equivalent rigidity. A steering control device comprising: a steering control means for performing a steering control by taking a quadratic term as an equivalent moment of inertia and taking the imaginary part as an equivalent damping into a steering system. The steering control means includes
I _SW : Steering wheel inertia moment I _mt : Motor inertia moment C _SW : Steering system damping coefficient C _m : Motor damping control amount K _t : Torsion bar rigidity K _g : Motor assist T _SW : Input torque at steering wheel θ ₁ : Steering shaft rotation angle K _v : Equivalent rigidity I _v : Equivalent inertia moment C _v : Equivalent damping s: When Laplace operator is used, the following formula:
_{(K t K g I SW +} I mt + I V) θ 1 s 2 + (K t K g C SW + C m + C V) θ 1 s + K v θ 1 = K t K g T SW
The steering control device according to claim 1, wherein the steering control is executed based on the control.   The steering control means compensates for the equivalent stiffness, the equivalent damping, and the equivalent inertia moment in order to suppress a change in steering feeling due to at least the vehicle speed, vehicle mass, longitudinal load distribution, and dimensionless inertia moment. The steering control device according to any one of claims 1 to 3, wherein the steering control is performed at a time.   The steering control device according to claim 4, wherein the steering control unit performs the steering control so that a damping ratio of the steering system is constant.   The steering control means performs the steering control such that the steering system has a damping ratio corresponding to at least the vehicle speed, the vehicle mass, the longitudinal load distribution, and the dimensionless inertia moment. The steering control device according to claim 4.   The said steering control means performs the control which changes at least 1 or more of the assist by the said motor, damping | damping, and steering rigidity as said steering control. Steering control device.

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