JP2005059695A - Automotive steering feeling setting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automotive steering feeling setting device capable of setting desired steering feeling. <P>SOLUTION: The automotive steering feeling setting device comprises a steering force characteristic control means (a second control unit 24) to control the steering force characteristic, a vehicular responsive characteristic control means (a third control unit 28) to control the vehicular responsive characteristic, and a steering feeling setting means to set desired steering feeling. The steering feeling setting means controls the steering force control means and/or the vehicular responsive characteristic control means so that the ratio of the decrease in the vehicular response to the decrease in the steering force in an off-center area before the predetermined steering force is achieved from the start of turning a steering wheel constantly irrespective of the change in vehicle speed when a driver turns the steering wheel in a straight-running condition at a speed not lower than a predetermined value, and then, returns the steering wheel, and a ratio of the decrease in the vehicular response to the decrease in the steering force in an on-center area with the steering force not more than a predetermined value are within a predetermined ratio range. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a steering feeling setting device for an automobile, and more particularly, to a steering feeling setting device for an automobile that sets a steering force characteristic and a vehicle response characteristic to a desired steering feeling.

Recently, for example, an electric power steering apparatus that uses the power of an electric motor to act on a steering system to reduce an operating force as shown in Japanese Patent Application Laid-Open No. 8-332964 has been used. It is coming. The electric power steering apparatus includes a steering force detection unit that detects a driver's steering force (steering torque) by the steering force detection unit and simultaneously drives the motor so as to generate a predetermined correction torque based on the vehicle speed. The current is controlled to reduce the driver's steering force.
In such an electric power steering apparatus, in order to obtain a good steering feeling and high steering performance, characteristics such as a torsion bar and power assist are tuned, and a characteristic of steering force with respect to a steering angle (hereinafter referred to as “steering force”). Characteristic ”) is set to a desired steering force characteristic (target steering force characteristic).
JP-A-8-332964

However, the conventional electric power steering device is built for each vehicle type so as to have a desired steering force characteristic that the designer considers desirable, but when the vehicle speed changes, Since the steering force characteristic also changes from the inherent characteristic, the desired steering force characteristic is exhibited only in a limited driving state.
On the other hand, when the driver cuts the steering wheel from a straight traveling state in a high speed range of, for example, 50 km / h or more, the steering force characteristic also changes with the change of the vehicle speed, so that the steering feeling is deteriorated. In addition, the present inventors have found a new problem that a desired steering feeling can be obtained by making the steering force characteristic substantially constant in such a speed range.

Moreover, even if the steering speed, the vehicle weight, the road surface state, or the like changes, a problem has also been found that a desired steering feeling can be obtained if the steering force characteristic can be made substantially constant.
Furthermore, if each automobile manufacturer can apply the desired steering feeling that the manufacturer considers desirable to their own various vehicles and can set the same steering feeling even if the vehicle types are different, the desired steering feeling can be set. The feeling becomes the DNA steering feeling of the manufacturer, and a good image regarding the steering feeling of the automobile manufacturer can be given to the driver.
In order to solve the above newly found problem, a desired steering feeling may be quantified, and the quantified feeling value may be created in a hardware (mechanical) or controllable manner. However, no attempt has been made to quantify such steering feeling.

Therefore, the present invention has been made to solve the above-described new problem, and an object thereof is to provide an automobile steering feeling setting device that can set a desired steering feeling.
SUMMARY OF THE INVENTION An object of the present invention is to provide an automobile steering feeling setting device that can set substantially the same desired steering feeling even if the vehicle types are different.
An object of the present invention is to provide a steering feeling setting device for an automobile capable of improving a safety and setting a desired steering feeling without anxiety.
An object of the present invention is to provide a steering feeling setting device for an automobile that can set a desired steering feeling by quantifying the steering feeling by “following ability of vehicle response”.

In order to achieve the above object, a steering feeling setting device for an automobile of the present invention includes a steering force characteristic control unit that controls a steering force characteristic, a vehicle response characteristic control unit that controls a vehicle response characteristic of a vehicle, and a desired Steering feeling setting means for setting the steering feeling of the vehicle, and the steering feeling setting means relates to a change in the vehicle speed when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel. Rather than always, the ratio of the decrease in the vehicle response to the decrease in the steering force in the off-center region from the start of the return of the steering wheel to the predetermined steering force, and the vehicle response to the decrease in the steering force in the on-center region that is less than or equal to the predetermined steering force The steering force control means and / or the vehicle response characteristic control means are controlled so that the rate of decrease of the vehicle falls within a predetermined ratio range. It is characterized in that have been made.
In the present invention configured as described above, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the driver always reduces the steering force felt in the off-center region regardless of the change in the vehicle speed. Since the rate of decrease in vehicle response is within a predetermined range, it is appropriate to decrease the vehicle response relative to the decrease in steering force. You can feel a good steering feeling. As a result, according to the present invention, it is possible to set the desired steering feeling by quantifying the steering feeling based on the “trackability of the vehicle response”. Further, it is possible to provide a steering feeling with improved safety and no anxiety.

In the present invention, preferably, the steering feeling setting means relates to a change in steering speed, vehicle weight, and / or road surface condition when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel. Rather than always, the ratio of the decrease in the vehicle response to the decrease in the steering force in the off-center region from the start of the return of the steering wheel to the predetermined steering force, and the vehicle response to the decrease in the steering force in the on-center region that is less than or equal to the predetermined steering force The steering force control means and / or the vehicle response characteristic control means are controlled so that the rate of decrease falls within a predetermined ratio range.
According to the present invention configured as described above, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the steering speed, the vehicle weight, and Or, it is possible to always feel a steering feeling with good “trackability of vehicle response” regardless of changes in road surface conditions.

In the present invention, preferably, the ratio of the decrease in the vehicle response to the decrease in the steering force in the off-center region to the ratio of the decrease in the vehicle response to the decrease in the steering force in the on-center region is within a range of 1.5 to 2.5. is there.
According to the present invention configured as described above, the ratio of the decrease in the vehicle response to the decrease in the steering force in the off-center region with respect to the decrease in the vehicle response to the decrease in the steering force in the on-center region is 1.5-2. When it is within the range of 5, it is possible to feel a steering feeling with particularly good “vehicle response tracking”.

In the present invention, preferably, the steering force feeling setting means is configured such that when the driver cuts the steering wheel from a straight traveling state of a predetermined vehicle speed or higher and then returns the steering wheel, the steering force decreases from the start of the steering wheel return, but the vehicle response The steering force control means and / or the vehicle response characteristic control means are controlled so that the time until the increase is within a predetermined range with respect to the half cycle time of steering of the steering wheel.
According to the present invention configured as described above, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the steering force decreases from the start of the steering wheel return, but the vehicle response increases. The time until the time is within a predetermined range with respect to the half cycle time of steering of the steering wheel, the driver can feel a steering feeling with good “vehicle response tracking”. .

In the present invention, preferably, the range of the predetermined ratio is such that the time during which the steering force decreases and the vehicle response increases from the start of the return of the steering wheel is 0.2 or less with respect to the half cycle time of the steering of the steering wheel. It is.
According to the present invention thus configured, the time during which the steering force decreases and the vehicle response increases from the start of the return of the steering wheel is 0.2 or less with respect to the half cycle time of the steering of the steering wheel. Therefore, since the time during which an undesirable vehicle response increases is shortened, it is possible to feel a steering feeling with good “trackability of vehicle response”.

The present invention relates to a steering feeling setting device for an automobile for setting a desired steering feeling, a steering force characteristic setting means for setting a predetermined target steering force characteristic, and a vehicle response for setting a predetermined target vehicle response characteristic. Characteristic setting means, these steering force characteristic setting means and vehicle response characteristic setting means, the target steering force characteristic and the target vehicle response characteristic, the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher, and then When the steering wheel is returned, the vehicle response is always reduced with respect to the reduction of the steering force in the off-center region from the start of the steering wheel return to the predetermined steering force regardless of changes in the vehicle speed, steering speed, vehicle weight and / or road surface condition. And the ratio of the decrease in vehicle response to the decrease in the steering force in the on-center region that is equal to or less than the predetermined steering force is within the predetermined ratio range. Sea urchin, is characterized in that you have set.
In the present invention configured as described above, in order to set a desired steering feeling, the steering force characteristic setting means sets the predetermined target steering force characteristic in advance, and the vehicle response characteristic setting means sets the predetermined target vehicle. By setting the response characteristics, specifically, mechanically, when the driver cuts the steering wheel from a straight traveling state above a predetermined vehicle speed and then returns the steering wheel, the vehicle speed, steering speed, vehicle weight and Regardless of the change in the road surface condition, the ratio of the decrease in the vehicle response to the decrease in the steering force in the off-center region and the ratio of the decrease in the vehicle response to the decrease in the steering force in the on-center region are always within the predetermined ratio range. Therefore, it is appropriate to reduce the vehicle response with respect to the decrease in the steering force, and the driver can control the steering wheel with good “vehicle response followability”. -Ring can feel. As a result, according to the present invention, it is possible to set the desired steering feeling by quantifying the steering feeling based on the “trackability of the vehicle response”. Further, it is possible to provide a steering feeling with improved safety and no anxiety.

  According to the steering feeling setting device for an automobile of the present invention, a desired steering feeling can be set. In particular, almost the same desired steering feeling can be set even if the vehicle types are different. Thus, it is possible to set a desired steering feeling that improves safety and does not cause anxiety, and it is possible to set a desired steering feeling by quantifying the steering feeling.

FIG. 1 is a perspective view showing an example of an electric power steering apparatus for an automobile to which the present invention is applied. As shown in FIG. 1, an electric power steering apparatus 1 for an automobile includes a handle (steering wheel) 2, and this handle 2 is connected to an upper end of a steering shaft 4, and a steering force for operating the handle 2 is used for steering. It is transmitted to the shaft 4. The upper end of the intermediate shaft 6 is connected to the lower end portion of the steering shaft 4 via a universal joint, and the VGR device 8 that is a vehicle response variable mechanism is connected to the lower end portion of the intermediate shaft 6 so that the front wheels with respect to the steering angle of the steering wheel The transmission ratio of steering can be changed. An intermediate shaft 10 is coupled to the lower end portion of the VGR device 8, and a steering gear box 12 is provided at the lower end portion of the intermediate shaft 10. Tie rods 14 are connected to both sides of the steering gear box 12, and tires (wheels) 16 are attached to the tie rods 14.
In the present embodiment, the VGR device 8 that changes the transmission ratio of the front wheel steering with respect to the steering angle is used as the vehicle response variable mechanism, but in addition, a 4WS device that changes the transmission ratio of the rear wheel steering angle, An SBW (steer-by-wire device), ACS (active suspension), SDS (skyhook damping suspension), BBW (brake-by-wire) device, or the like may be used.

A rack and pinion mechanism (not shown) is provided in the steering gear box 12 described above, and the lower end of the intermediate shaft 10 is connected to the pinion. On the other hand, tires 16 are connected to both sides of the rack via the tie rods 14 as described above.
The steering gear box 12 is provided with an electric motor 18 that applies force to the pinion side via a reduction gear (not shown), and a torque sensor (not shown) is provided between the reduction gear and the intermediate shaft 10. Is arranged. This torque sensor is for detecting a steering force (steering torque) acting on the intermediate shaft 10.

These VGR device 8, electric motor 18, and torque sensor are each connected to a control unit 20.
As will be described in detail later, the control unit 20 includes a first control unit (normal assist control unit) 22, a second control unit (center feel control unit) 24, a motor current control unit 26, and a third control unit (vehicle). Response control unit) 28, and the first control unit 22, the second control unit 24, and the motor current control unit 26 use the torque sensor detection value (steering torque), the vehicle speed, and the like to detect the torque sensor detection value. And the electric motor 18 is controlled so as to realize a target steering force characteristic for setting a desired steering feeling (DNA steering feeling). Further, the third control unit 28 controls the vehicle speed and A target vehicle for setting a desired steering feeling (DNA steering feeling) while changing a transmission ratio of front wheel steering with respect to a steering angle based on a steering angle or the like Stepping motor 30 so as to realize the answer characteristics (see FIG. 2) are controlled.

Next, the VGR device 8 that is a vehicle response variable mechanism will be described with reference to FIGS. The VGR device 8 is for changing the ratio (transmission ratio: R = θ / θw) between the steering angle (θ) of the steering wheel 2 and the wheel steering angle (θw) of the wheel 16.
The VGR device 8 has an input shaft 34 disposed on the same axis as the intermediate shaft 10 so that rotation of the intermediate shaft 6 is input to the input shaft 34 via integrated input gears 35 and 36. It has become.

A planetary gear mechanism 37 is provided between the input shaft 34 and the intermediate shaft 10, and the planetary gear mechanism 37 is disposed on the sun gear 38 and a sun gear 38 fixed on the input shaft 34. A plurality of pinion gears 39, a ring gear 40 arranged outside these pinion gears 39 and fixed to the intermediate shaft 10, and fitted and supported on the input shaft 34 so as to be relatively rotatable, and each pinion gear via a pinion shaft 41. And a carrier 42 for supporting 39.
A sector gear 43 is provided integrally with the carrier 42, and a pinion gear 45 fixed to the rotating shaft 30 a of the stepping motor 30 is engaged with the sector gear 43.

  When the steering wheel 2 is steered, the stepping motor 30 is rotationally driven according to the output signal from the control unit 20, whereby the sun gear 38 is rotated by an amount corresponding to the steering angle θ in the planetary gear mechanism 37, The carrier 42 is rotated according to the rotation of the stepping motor 30, whereby the amount of rotation of the ring gear 40 or the intermediate shaft 10 corresponding to the wheel steering angle θw is increased or decreased, and the transmission ratio R of the steering angle θ to the wheel steering angle θw is increased. It is variably controlled.

Next, a steering force characteristic model applied to the automobile steering feeling setting device of the present embodiment will be described with reference to FIGS. 5 and 6.
This steering force characteristic model expresses the steering force as a function model of the steering angle. By this steering force characteristic model, a target steering force characteristic for setting a desired steering feeling is obtained simply and accurately. be able to.
First, the steering force characteristic model can be applied when traveling at a high vehicle speed and substantially straight. Specifically, the high vehicle speed is a speed of about 50 km / h or more, and the almost straight traveling state is a state where the steering wheel is operated slowly, specifically, the steering wheel is repeatedly operated at a frequency of 0.2 Hz or less. A steering state is assumed in which the lateral acceleration (lateral G) is 0.2 G or less. Hereinafter, such a traveling state is referred to as a “center feel sensitive area”.

  Steering force characteristics at such high speed straight travel are represented by a spring component (represented by a nonlinear function including the steering angle), a viscosity component (proportional to the steering angular velocity), and a friction component (a nonlinear function including the steering angular velocity). The steering force characteristic model (the steering force expressed as a function model of the steering angle) was set.

Next, the contents of the steering force characteristic model will be described in detail with reference to FIGS. FIG. 5 is a diagram illustrating a steering force characteristic model, and FIG. 6 is a diagram illustrating a spring component, a viscosity component, and a friction component in the steering force characteristic model.
As shown in FIG. 5, the steering force characteristic model is a model including a spring component, a viscosity component, and a friction component. Since the present invention is for setting a desired steering feeling in the center-feel sensitive region, the steering wheel is slowly steered (frequency of 0.2 Hz) as described above, so that the inertia component is The model does not include.

The spring component is set as an exponential function shown in the following equation (Equation 1). In this equation (Equation 1), θ is a steering angle, and Kp and Tp are characteristic parameters of the spring component. The spring component is basically proportional to the steering angle. However, since the spring component becomes saturated when the steering angle exceeds a predetermined steering angle, the characteristic parameter Kp corresponds to this saturation state, and the characteristic parameter Tp is an exponential function. Indicates a constant. Thus, the equation (Equation 1) indicating the spring component is a nonlinear function.
Thus, the spring component is defined as being expressed by a nonlinear function including the steering angle.

The viscous component is a force proportional to the steering angular velocity, and is expressed by the following equation (Equation 2). In this equation (Equation 2), Kd is a characteristic parameter of the viscous component. Thus, the viscous component is defined as being proportional to the steering angular velocity.

The friction component is a force that is substantially proportional to the steering angular velocity when the steering angular velocity is small, and becomes a certain amount of frictional force (saturated state) when the steering angular velocity increases. This friction component is set as an exponential function shown in the following equation (Equation 3). In this equation (Equation 3), Kf and Tf are characteristic parameters of the friction component. The characteristic parameter Kf corresponds to this saturation state, and the characteristic parameter Tf indicates the time constant of the exponential function. Thus, the equation (Equation 3) indicating the spring component is a nonlinear function.
Thus, the friction component is defined as a nonlinear function including the steering angular velocity.

Thus, in the steering force characteristic model, the spring component, the viscosity component, and the friction component are set, and the steering force (steering torque) is set as the total value of these components. That is, the steering force characteristic model is expressed by the following equation (Equation 4).

ただし、ｍは車両質量、Ｖは車速、Ｉは車両のヨー慣性モーメント、ｌfは車両重心から前車軸までの距離、ｌrは車両重心から後車軸までの距離、βは車両重心位置での横すべり角、ｒはヨーレート、Ｋfは前輪のコーナリングパワー、Ｋrは後輪のコーナリングパワー、δfは前輪の車輪舵角（＝ハンドル操舵角θ／ＶＧＲの伝達比Ｒ＝前輪の車輪舵角θｗ）、δｒは後輪の車輪舵角（ただし、４ＷＳの場合のみであり、２ＷＳではδr＝０となる）である。
目標車両応答特性を設定するために、ヨーレートｒを所望の特性になるように制御するのであれば（横Ｇは制御対象としない）、ヨーレートｒを目標に一致させるような制御入力δfを設定すれば良いし、また、横Ｇを所望の特性になるように制御するのであれば（ヨーレートは制御対象としない）、横すべり角βを目標に一致させるような制御入力δfを設定すれば良い。ここで、４ＷＳを採用する場合には、ヨーレートと横Ｇを同時に制御することができる。 Next, the steering feeling setting device for an automobile according to the present embodiment sets (calculates) a target vehicle response characteristic by solving simultaneous equations of (Equation 5) and (Equation 6) which are the following motion equations of the vehicle. )

Where m is the vehicle mass, V is the vehicle speed, I is the vehicle yaw moment of inertia, lf is the distance from the vehicle center of gravity to the front axle, lr is the distance from the vehicle center of gravity to the rear axle, and β is the side slip angle at the vehicle center of gravity position. , R is the yaw rate, Kf is the cornering power of the front wheel, Kr is the cornering power of the rear wheel, δf is the wheel steering angle of the front wheel (= steering ratio θ / VGR transmission ratio R = wheel steering angle θw of the front wheel), δr is The wheel steering angle of the rear wheels (however, only in the case of 4WS, δr = 0 in 2WS).
If the yaw rate r is controlled to be a desired characteristic in order to set the target vehicle response characteristic (the lateral G is not a control target), a control input δf that matches the yaw rate r with the target is set. In addition, if the lateral G is controlled to have a desired characteristic (the yaw rate is not controlled), the control input δf may be set so that the side slip angle β matches the target. Here, when 4WS is employed, the yaw rate and the lateral G can be controlled simultaneously.

FIG. 7 is a block diagram showing a control unit of the steering feeling setting device for an automobile according to the present embodiment. As shown in FIG. 7, the control unit 20 includes a first control unit (normal assist control unit) 22, a second control unit (center feel control unit) 24, a motor current control unit 26, and a third control unit (vehicle). Response control unit) 28.
Further, the vehicle steering feeling setting device of the present embodiment includes a torque sensor 50 for detecting a steering force (steering torque) acting on the intermediate shaft 10 and a lateral G sensor for detecting lateral acceleration (lateral G). 52, a vehicle speed sensor 54 for detecting the vehicle speed, a steering angle sensor 56 for detecting the steering angle of the steering wheel, a yaw rate sensor 58 for detecting the yaw rate, a vehicle weight sensor 60 for detecting the vehicle weight, and a road surface for detecting the road surface condition or the road surface friction coefficient. A μ sensor 62 is provided, and the output value of each of these sensors is input to the control unit 20.

The first control unit 22 is a control unit that performs normal assist control. The first control unit 22 reduces the output value of the torque sensor 50, that is, generates an assist force in a direction that reduces the steering force. It is a control part for controlling. The torque sensor value from the torque sensor 50 is input to the first control unit 22, noise is cut by the filter 64, and the reference target current I ₀ is calculated by the control gain K ₁ . As will be described later, the control gain K1 of the first control unit is set based on the values of the lateral G sensor 52 and the vehicle speed sensor 54 (see FIG. 8). As a result, the control by the first control unit In the sensitive area, it is suppressed or prohibited.

  The second control unit 24 is a center feel compensation control unit, and has a center feel sensitivity range (as described above, at a high vehicle speed of 50 km / h or more, for example, a 0.2 Hz sine wave and a lateral G of 0.2 G or less. This is a control unit for controlling the electric motor 18 so as to obtain a target steering force set to obtain a desired steering feeling (DNA steering feeling) during traveling.

  The second control unit 24 includes a target steering force calculation unit 66. The target steering force calculation unit 66 includes a torque sensor 50, a lateral G sensor 52, a vehicle speed sensor 54, a steering angle sensor 56, a yaw rate sensor 58, a vehicle. Output values of the weight sensor 60 and the road surface μ sensor 62 are input. The target steering force calculation unit 66 uses the steering force characteristic model expressed by the steering angle described above, and from the output values from these sensors, the characteristic parameters (Kp, Tp, A desired steering feeling is obtained by setting the values of Kd, Kf, Tf) and realizing the target steering force characteristic.

  The second control unit 24 includes a filter 68 that is a low-pass filter, and the filter 68 can obtain only the value of the torque sensor 50 in a band (for example, a band including 0.2 Hz) corresponding to the center feel sensitive area. It has become.

  Next, the deviation between the target steering force calculated by the target steering force calculator 66 and the actual steering force (Ts2), which is the filtered torque sensor value, is converted into a physical quantity by the control gain K3. Here, as will be described later, the control gain K3 is set based on the values of the lateral G sensor 52 and the vehicle speed sensor 54. As a result, the control by the second control unit is suppressed or suppressed in the non-center feel sensitive region. It is prohibited (see FIG. 8).

Next, the reference target current I ₀ output from the first control unit 22 and the compensation target current _If are added to calculate the target current I. Specifically, the sign is set to (+) when the assist force is increased in order to decrease the steering force, and (−) when the assist force is decreased in order to increase the steering force. calculation of subtracting a compensation target current I _f with respect to the target current I ₀ is performed.

ここで、式（数７）において、（Ｉ）は目標電流、（Ｔｓ１）はフィルタ６４を通ったトルクセンサ値、（Ｋ１）は第１制御部の制御ゲイン、（ｆ（θ））は式（数４）により表現された操舵力特性モデル出力、（Ｔｓ２）はフィルタ６８を通ったトルクセンサ値、（Ｋ３）は第２制御部の制御ゲインである。 The motor current control unit 26 is a control unit for performing feedback control so that the current supplied to the electric motor 18 becomes the target current I. Therefore, the motor current control unit 26 includes a control gain K2, a PI control unit 70 that performs proportional-integral control, and a motor characteristic compensation unit 72.
The target current I supplied to the electric motor 18 calculated in this way is expressed by the following equation (Equation 7).

Here, in Expression (7), (I) is the target current, (Ts1) is the torque sensor value that has passed through the filter 64, (K1) is the control gain of the first control unit, and (f (θ)) is the expression The steering force characteristic model output expressed by (Equation 4), (Ts2) is the torque sensor value that has passed through the filter 68, and (K3) is the control gain of the second control unit.

  Next, FIG. 8 is a correction map of proportional gains of the first control unit and the second control unit. The correction map shown in FIG. 8 has four areas of a center feel sensitive area, a transition area I, a transition area II, and a non-center feel sensitive area. In each area, the control gain K1 (K1 = K1 * β ), K3 (K3 = K3 * α) are corrected. Here, α and β are correction coefficients, which vary in the range of 0-1.

First, in the center feel sensitive region, the correction coefficients are set to α = 1 and β = 0. For this reason, the control gain K1 of the first control unit is 0, and the current control of the electric motor by the first control unit is prohibited. On the other hand, since the control gain K3 of the second control unit is used as it is, the compensation current I _f is generated by the second control unit 24 so that the target steering force preset based on the above-described steering force characteristic model is generated. Is set. As a result, in the center feel sensitive region, a desired steering force characteristic is obtained, and the steering performance is improved. In addition, it is possible to prevent control hunting (control interference) that occurs when the first control unit 22 and the second control unit 24 operate simultaneously.

Next, in the non-center feel sensitive region, the correction coefficients are set as α = 0 and β = 1. For this reason, the control gain K3 of the second control unit is 0, and the electric motor current control by the second control unit is prohibited. On the other hand, since the control gain K1 of the first control unit is used as it is, the reference target current I ₀ is set by the first control unit 22 so that the torque sensor value becomes small. As a result, normal assist control is performed in the non-center feel sensitive region, and steering performance is improved. In addition, it is possible to prevent control hunting (control interference) that occurs when the first control unit 22 and the second control unit 24 operate simultaneously.

Next, the transition area I is an area applied when the running state of the vehicle changes from the non-center feel area to the center feel sensitive area. In this transition region I, the correction coefficient α changes from 0 → 1, and the correction coefficient β changes from 1 → 0.
The transition region II is a region applied when the traveling state of the vehicle changes from the center feel region to the non-center feel sensitive region. In this transition region II, the correction coefficient α changes from 1 → 0, and the correction coefficient β changes from 0 → 1.

In these transition regions I and II, the reference target current I ₀ is set based on the control gain K1 corrected in the first controller, and the compensation current _If is corrected based on the control gain K3 corrected in the second controller. The target current I is calculated by adding these currents. As a result, in these transition areas I and II, the normal assist control can be performed and the target steering force can be obtained together, thereby improving the steering performance. Further, when the driving state of the vehicle shifts between the non-center feel area and the center feel sensitive area, a different transition area is applied depending on the transition direction. Control hunting (control interference) caused by simultaneous operation of the second control unit 24 can also be prevented.

  Again, as shown in FIG. 7, the third control unit 28 is a vehicle response control unit for setting a desired steering feeling, in order to change the transmission ratio of the steering angle to the wheel steering angle by the VGR device 8. Further, a control unit for controlling the stepping motor 30. The vehicle response control unit is a target vehicle response calculation unit to which output values of the torque sensor 50, the lateral G sensor 52, the vehicle speed sensor 54, the steering angle sensor 56, the yaw rate sensor 58, the vehicle weight sensor 60, and the road surface μ sensor 62 are input. 74 and an output signal generator 76 for generating an output signal corresponding to the calculated value obtained by the target vehicle response calculator 74, and a signal output from the output signal generator 76 is sent to the stepping motor 30. At the same time, the rotation amount of the stepping motor 30 is detected by the motor rotation angle sensor 78 and returned to the output signal generator 76 as a feedback signal.

The target vehicle response calculation unit 74 sets the output values of the torque sensor 50, the lateral G sensor 52, the vehicle speed sensor 54, the steering angle sensor 56, the yaw rate sensor 58, the vehicle weight sensor 60, and the road surface μ sensor 62 in the center feel sensitive area. Based on this, a target vehicle response characteristic for obtaining a desired steering feeling is set, and a transmission ratio R of the steering angle θ to the wheel steering angle θw is calculated so as to realize the target vehicle response characteristic. .
The output signal generation unit 76 outputs a drive signal based on the transmission ratio R calculated by the target vehicle response calculation unit 74 to the stepping motor 30 in order to obtain a desired steering feeling in the center feel sensitive region, and as a result. The desired wheel steering angle θw can be obtained.
In the non-center feel sensitive region, as shown in FIG. 9, the transmission ratio R is set to increase as the vehicle speed increases.

In the present embodiment, the driver feels “steering force / vehicle response play feeling”, “rigidity feeling”, “spring feeling” according to the steering force and the vehicle response (vehicle behavior due to the yaw rate and / or lateral G) generated by the steering. ”,“ Looseness when cutting ”,“ Looseness when returning ”, and“ Vehicle response extension ”and“ Vehicle response followability ”, or each of these indicators or The desired steering feeling (DNA steering feeling) is quantified by the combination, and thereby the desired steering feeling (DNA steering feeling) is set.
According to the present embodiment, since the desired steering feeling is quantified by using these seven indicators or each indicator, “vehicle speed”, “steering speed”, “vehicle weight” and / or “road surface condition” Regardless of the change, the almost constant desired steering feeling (DNA steering feeling) can be controlled or mechanically set.

As described above, according to the present embodiment, a desired steering feeling (DNA steering feeling) can be quantified, so that an automobile manufacturer can perform the same desired steering regardless of the type of vehicle as necessary. A feeling (DNA steering feeling) can be set, and a good image regarding the steering feeling of the automobile manufacturer can be given to the driver.
The desired steering feeling (DNA steering feeling) is preferably applied to the above-mentioned center feel sensitive area, while the steering feeling during turning (non-center feel sensitive area) is center feel sensitive area. Unlike the above, it is preferable to give the vehicle type specific characteristics (steering feeling) rather than the same steering feeling.

In the present embodiment, as will be described in detail later, the target steering force characteristic and / or the target vehicle response characteristic is realized by controlling the steering force characteristic and / or the vehicle response characteristic, so that the driver can control the center feel. Regardless of changes in vehicle speed, steering speed, vehicle weight, and / or road surface μ in the sensitive region, it is possible to always feel a substantially constant desired steering feeling (DNA steering feeling). .
Specifically, the parameter value of each component of the steering force characteristic model is set so as to realize the target steering force characteristic, and the transmission ratio R of the vehicle response variable mechanism is set so as to realize the target vehicle response characteristic. To do.
In this way, in the present embodiment, the electric motor 18 and the stepping motor 30 are controlled so as to achieve the target steering force characteristic and / or the target vehicle response characteristic. As a result, the steering force felt by the driver in the center feel sensitive region. The desired steering feeling (DNA steering feeling) can be set such that the relationship between the vehicle response and the vehicle response felt by the driver is a predetermined relationship.

Next, a control flow for setting a desired steering feeling (DNA steering feeling) according to the present embodiment will be described with reference to FIG. In FIG. 10, S indicates each step.
As shown in FIG. 10, first, in S1, each sensor value is input. Specifically, torque, lateral acceleration (lateral G), vehicle speed detected by torque sensor 50, lateral G sensor 52, vehicle speed sensor 54, steering angle sensor 56, yaw rate sensor 58, vehicle weight sensor 60, and road surface μ sensor 62. Steering angle, yaw rate, vehicle weight, road surface condition (road surface friction coefficient).

  Next, in S2, “steering force / feeling of vehicle response”, “rigidity”, “spring” for setting a desired steering feeling (DNA steering feeling) based on each input sensor value. "Target steering force" and "Target vehicle response" satisfying the seven indexes of "feel", "feeling of slipping when cutting", "feeling of slipping when returning", "elongation of vehicle response" and "trackability of vehicle response" Set. Specifically, the target steering force is calculated by the second control unit 24 shown in FIG. 7 described above, and the target vehicle response is calculated by the third control unit 28.

  Next, in S3, the electric power steering device (specifically, the electric motor 18 in FIG. 7) is controlled to realize the target steering force set in S2, and in S4, the target vehicle response set in S2 is realized. Thus, the VGR device (specifically, the stepping motor 30 in FIG. 7) is controlled to realize (set) a desired steering feeling (DNA steering feeling).

Next, referring to FIGS. 11 to 14, “steering force / play feeling of vehicle response” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described.
“A sense of play of steering force / vehicle response” means a steering feeling when the driver feels the response of the steering wheel when the driver cuts the steering wheel from the straight traveling state and then feels the vehicle response. If there is an appropriate relationship between the timing at which the driver feels the response of the steering wheel and the timing at which the vehicle response is felt, the driver feels that the steering wheel has been cut without waste. Steering feeling.
On the other hand, if the driver starts steering from a straight line and feels responsiveness with the steering wheel turned off, or the vehicle does not start to move, or if the vehicle feels like it has started moving without touching the steering wheel The play feeling of the steering force / vehicle response is bad, that is, it is felt that the steering wheel is cut wastefully. In such a case, the driver feels that the vehicle will not respond to the steering wheel operation, so the driver cannot travel on the target course and deviates from the lane at the corner, or the steering wheel is overcut. It is a factor that causes proper operation.

  When a steering feeling with a good sense of play of steering force / vehicle response is set as in this embodiment, the timing when the steering wheel feels (feeling perception threshold) and the vehicle response (perception of vehicle response) are sensed. Since the relationship with the timing at which the threshold value is sensed is appropriate, the driver feels that the steering wheel has been cut without waste, and therefore the safety can be improved and the steering feeling without anxiety can be felt. .

With reference to FIG. 11, the “steering force / play feeling of vehicle response” described above will be specifically described. FIG. 11 is a diagram showing a steering force F, a steering angle θ, and a yaw rate Y in a desired base steering feeling (DNA steering feeling) set according to this embodiment. Here, the base means a standard vehicle speed (100 km / h), steering speed (10 deg / s), vehicle weight (vehicle weight when two passengers are present), and road surface condition (high μ road). I mean.
As shown in FIG. 11, when the driver starts steering from the straight traveling state, the steering force F first rises, then the steering angle θ rises with a delay, and then the yaw rate Y rises. Note that the steering angle θ rises later than the steering force F is due to the effects of friction of the steering device, and the yaw rate Y rises further later due to the effects of tire deflection and the like.

Here, in this embodiment, when the driver starts steering the steering wheel from the straight traveling state, the steering force is the steering force that feels the steering wheel power so that the driver feels a good “steering force / feeling of vehicle response”. Is 6N (perception threshold for response), and the vehicle response is felt when the yaw rate is 0.4 deg / s (perception threshold for vehicle response) (or the lateral acceleration (lateral G) is 0. 0). And the dead zone of the steering force (response), which is the steering angle at which the steering feels the response of the steering wheel, is set to the steering angle (θ = 0.8 to 1.2 deg), The delay time (response delay time) of the vehicle response with respect to the response from the timing when the steering wheel feels the response to the timing when the vehicle response is felt is set to T _D = 0.15 to 0.20 s.
In the present embodiment, the steering force F and the yaw rate Y shown in FIG. 11 are set to the target steering force of the second control unit 24 in FIG. 7 described above so that such “steering force / feeling of vehicle response” can be achieved. The calculation is performed by the calculation unit 66 and the target vehicle response calculation unit 74 of the third control unit 28.

As shown in FIG. 11, the steering force F (= F _A ) exceeds 6N (perception threshold of response) at time t _A after the driver starts steering from the straight traveling state. The steering angle θ (= θ _A ), that is, the size of the dead zone of the steering force is in the range of 0.8 to 1.2 deg. Next, at time t _B after the response delay time (T _D ), the yaw rate Y (= Y _B ) exceeds 0.4 deg / s (perception threshold for vehicle response), and the steering angle at this time θ (= θ _B ) is the size of the dead zone of the vehicle response. Further, the difference between the “dead zone size θ _B of the vehicle response” and the “dead zone size θ _A of the steering force (response)” is the “lag angle of response to response (= θ _B −θ _A )”. .
As described above, in the present embodiment, “the steering force (response) dead band size θ _A ”, “response response perception threshold”, “vehicle response perception threshold”, and “response delay time (T _D)”. ) ”Within a predetermined range or value (θ _A = 0.8 to 1.2 deg, perception threshold of response = 6 N, perception threshold of vehicle response = 0.4 deg / s and t _D = 0.15 By setting to 0.20 s (= T _D )), the play feeling of steering force / vehicle response, which is an index for setting a desired steering feeling (DNA steering feeling), is quantified.

  Even if the desired steering feeling (DNA steering feeling) of the base as shown in FIG. 11 is set, if the vehicle speed, the steering speed, the vehicle weight and / or the road surface state change, the steering force F, Since the steering angle θ and the yaw rate Y also change, the desired steering feeling (DNA steering feeling) shown in FIG. 11 cannot be obtained. Hereinafter, the case where the vehicle speed is changed will be described with reference to FIG. 12, and the case where the steering speed is changed will be described with reference to FIG.

Next, FIG. 12 demonstrates the setting of the steering feeling by this embodiment when a vehicle speed increases rather than the base mentioned above. The vehicle speed is the same as that of the base described above except for the vehicle speed.
In FIG. 12, F, θ, and Y indicate the steering force, steering angle, and yaw rate at the base vehicle speed shown in FIG. 11, respectively. In FIG. 12, the subscript “1” at the steering force F, the steering angle θ, the yaw rate Y, and the time t indicates before control according to the present embodiment, and the subscript “2” indicates after control.

As shown in FIG. 12, when the vehicle speed increases with respect to the base, the steering force slightly decreases with respect to the base steering force F to become the steering force F ₁ , and the yaw rate (vehicle response) The yaw rate Y ₁ slightly increases with respect to the yaw rate Y. For this reason, the timing of feeling the response of the steering wheel (perception threshold 6N of response) is delayed from the time t _A to the time t _A1 , while the timing of feeling the vehicle response (perception threshold of vehicle response 0.4 deg / s) is accelerated from time t _B to time t _B1 . As a result, the dead zone size θ _A of the steering force (hand response) becomes larger than that in the base, and the response delay time (t _D1 = t _B1 −t _A1 ) in response to the hand is larger than that in the base. Since it becomes shorter and does not become constant, a desired steering feeling (DNA steering feeling) cannot be obtained with respect to the above-mentioned “steering force / feeling of vehicle response”.

Therefore, in the present embodiment, the target steering force characteristic and / or the target vehicle response characteristic set in the base is controlled (corrected) so that the response delay time becomes constant.
Specifically, as shown in FIG. 12, the steering force F ₂ is set so that the steering force increases as a whole, and thereby the timing at which the steering wheel feels responsive (perception threshold 6N) is set to the time t. and as soon as possible to t _A2 from _A1. At this time, the size of the dead zone of the steering force (response) is set within the range of 0.8 to 1.2 deg. Further, the yaw rate is slightly decreased, and the timing at which the vehicle response is sensed (vehicle response perception threshold of 0.4 deg / s) is delayed from time t _B1 to time t _B2 . In this way, by controlling both the target steering force characteristic and the target vehicle response characteristic, the size (θ _A2 ) and response delay time (t _D2 = t _B2 −t _A2 ) of the steering force (response) are reduced. It can be the same (constant) as in the case of the base shown in FIG. 11, and the same desired steering feeling (DNA steering feeling) can be obtained even if the vehicle speed increases.

FIG. 12 shows an example in which both the steering force and the yaw rate are controlled. However, since it is desirable not to control the vehicle response as much as possible, only the steering force is controlled and a dead zone of a certain steering force (response) is obtained. When the magnitude (θ _A ) and the constant response delay time (T _D ) can be set, it is preferable to control only the steering force without controlling (correcting) the vehicle response.
Also, when the vehicle speed decreases, the steering force increases while the yaw rate decreases, contrary to the case where the vehicle speed increases. Similarly, the target steering force characteristic and / or the target vehicle set in the base are reduced. The response characteristic may be controlled (corrected) so that the dead zone of the steering force (response) and the response delay time become constant.

Next, the steering feeling setting according to the present embodiment when the steering speed is increased from the above-described base will be described with reference to FIG. In addition, except the steering speed, it is the same as the case of the base mentioned above.
In FIG. 13, F, θ, and Y indicate the steering force, steering angle, and yaw rate at the base vehicle speed shown in FIG. 11, respectively, and the subscript “1” at the steering force F, steering angle θ, yaw rate Y, and time t. Indicates before control according to the present embodiment, and the subscript “2” indicates after control.

As shown in FIG. 13, when the steering speed increases with respect to the base, the steering force increases at an earlier timing than the base steering force F, becomes the steering force F ₁ , and the yaw rate (vehicle response) is The timing is slightly earlier than the base yaw rate Y, and the yaw rate Y ₁ is obtained. For this reason, the timing when the steering wheel feels responsive (perception threshold 6N) becomes faster from time t _A to time t _A1 , while the timing when the vehicle response is felt (vehicle response perception threshold 0.4 deg / s) is also slightly faster from time t _B to time t _B1 . As a result, the dead zone size θ _A of the steering force (hand response) is smaller than that in the base, and the response delay time (t _D1 = t _B1 −t _A1 ) is smaller than that in the base. Since it becomes long and does not become constant, it becomes impossible to obtain a desired steering feeling (DNA feeling) with respect to the above-described “steering force / play feeling of vehicle response”.

Therefore, in the present embodiment, the target steering force characteristic and / or the target vehicle response characteristic set in the base is controlled (corrected) so that the response delay time becomes constant.
Specifically, as shown in FIG. 13, the steering force F ₂ is such that the steering force is reduced as a whole, and thereby the timing at which the steering wheel feels responsive (perception threshold 6N) is set to the time t. It has been slow to t _A2 from _A1. At this time, the size of the dead zone of the steering force (response) is set within the range of 0.8 to 1.2 deg. Further, the yaw rate is slightly increased, and the timing at which the vehicle response is sensed (vehicle response perception threshold 0.4 deg / s) is advanced from time t _B1 to time t _B2 . In this way, by controlling both the target steering force characteristic and the target vehicle response characteristic, the size (θ _A2 ) and response delay time (t _D2 = t _B2 −t _A2 ) of the steering force (response) are reduced. It can be the same (constant) as in the case of the base shown in FIG. 11, and the same desired steering feeling (DNA steering feeling) can be obtained even if the steering speed increases.

Note that when the steering speed is increased (FIG. 13), as in the case where the vehicle speed is increased (FIG. 12), except for controlling both the steering force and the yaw rate, only the steering force is controlled to maintain a constant steering. When the size of the dead zone (θ _A ) and the constant response delay time (T _D ) can be set, only the steering force is controlled without controlling (correcting) the vehicle response. It is preferable.
Also, when the steering speed is lowered, the steering force is decreased, while the yaw rate is decreased at a timing later than that when the steering speed is increased. The target steering force characteristic and / or the target vehicle response characteristic may be controlled (corrected) so that the size of the dead zone and the response delay time of the steering force (hand response) may be constant.

  In the present embodiment, even when the vehicle weight or the road surface state changes, the target steering force characteristic and / or the target vehicle response characteristic set in the base is controlled (corrected) as in the case where the vehicle speed and the steering speed change. Thus, the size of the dead zone of the steering force (hand response) and the response delay time are made constant.

Next, referring to FIG. 14, how to set a desired steering feeling (DNA steering feeling) according to this embodiment regarding “steering force / play feeling of vehicle response” will be described. In FIG. 14, S indicates each step.
First, in S1, the steering angle θ (deg) of the steering wheel is input, and then, the process proceeds to S2, and the steering speed θ ′ (deg / s) is calculated from the steering angle θ. Next, in S3, the yaw rate Y (deg / s) is input, and the process proceeds to S4, where the yaw acceleration Y ′ (deg / s ² ) is calculated from the yaw rate Y.

Next, in S5, a time t _{B at} which the yaw rate Y becomes 0.4 deg / s is estimated from the yaw acceleration Y ′. Next, in S6, the estimated steering angle theta _A at time t _B from the response delay time T _D (= 0.15 to 0.20 S) before time corresponds to the time _{t A (= t B -T D} ) . Next, in S7, it is determined whether or not the steering angle θ _A , that is, the size of the dead zone of the steering force, is within the range of the steering angle 0.8 to 1.2 deg.
If it is determined in S7 that the steering angle is not within this range, the process proceeds to S8, in which it is determined whether or not the steering angle θ _A is less than 0.8 deg. When the steering angle θ _A is less than 0.8 deg, the process proceeds to S9, where t _A is the time when the steering angle θ is 0.8 deg. On the other hand, when the steering angle θ _A exceeds 1.2 deg, S10 is reached. Then, let t _A be the time when the steering angle θ is 1.2 deg. After S9 and S10, the process proceeds to S11 and is shown in FIG. 11 so that the yaw rate Y becomes 0.4 deg / s at the time after the response delay time T _D (0.15 to 0.20 s) from the time t _A. The base target vehicle response characteristic is corrected (see FIG. 7).

On the other hand, when it is determined in S7 that the steering angle θ _A is within the range of the steering angle 0.8 to 1.2 deg, S11 is not executed, that is, the target vehicle response characteristic is not corrected, and S12. the process goes to, to estimate the steering force F _a at time t _a. Next, proceeding to S13, it is determined whether or not the steering force F _A estimated at S9 is approximately 6N. If it is determined in S13 that the steering force F _{A is not} approximately 6N, the process proceeds to S14, and the target steering force characteristic of the base shown in FIG. 11 is corrected so that the steering force F becomes 6N at time t _A. (See FIG. 7). If it is determined in S13 that the speed is approximately 6N, the target steering force characteristic is not corrected.

As described above, in this embodiment, when the steering angle θ _A at the time t _A is within the range of the steering angle 0.8 to 1.2 deg, it is desirable that the vehicle response is not controlled as much as possible. Only the characteristics are controlled (the control is not performed when the steering force F _{A is} approximately 6N), while the steering angle θ _{A at the} time t _A is out of the range of the steering angle 0.8 to 1.2 deg. In this case, only the target vehicle response characteristic or both the target vehicle response characteristic and the target steering force characteristic are controlled. However, in addition to this, even when the steering angle θ _A at the time t _A is within the range of the steering angle 0.8 to 1.2 deg, both the target vehicle response characteristic and the target steering force characteristic are controlled. good.
Even when the steering angle θ _{A at} the time t _A falls outside the range of the steering angle 0.8 to 1.2 deg, it is desirable that the control amount (correction amount) of the vehicle response is small. _{When A} is less than 0.8 deg, the steering angle θ = 0.8 deg, which is the lower limit value of the predetermined range (= 0.8 to 1.2 deg) of the dead zone size θ _A of the steering force (response), the becomes time was t _a, when the steering angle theta _a exceeds 1.2Deg is a time satisfying the upper limit is the steering angle theta = 1.2Deg of the predetermined range (= 0.8 to 1.2Deg) By setting t _A , the control amount of the target vehicle response characteristic is made as small as possible.

Further, in the present embodiment, in S14 in FIG. 14, rather than correcting the target steering force characteristics of the base, forcibly imparting a predetermined steering force at time t _A, the steering force of 6N at time t _A You may make it exceed.
As described above, in this embodiment, by controlling (correcting) the target steering force characteristic and / or the target vehicle response characteristic, the size of the dead zone θ _A and the response delay time (t _D = t) of the steering force (response). _B− t _A ) can be the same (constant) as in the case of the base shown in FIG. 11, and even if the vehicle speed, the steering speed, the vehicle weight, and / or the road surface state change, the “steering force / vehicle response With respect to “feeling of play”, a similar (constant) desired steering feeling (DNA steering feeling) can be obtained.

Next, referring to FIG. 11 and FIG. 15, “stiffness” that is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described.
“Rigidity” has two indices, “feeling not stiff” and “feeling stiff”. When the driver cuts the steering wheel from a straight line, the driver feels a sense of stiffness and feels a certain hardness. This is the steering feeling that the vehicle feels responding without delay. In other words, the “feeling of rigidity” is a steering feeling that the driver feels that there is no inclusion on the way from the handle to the tire and that the handle is directly connected from the handle to the tire when the driver cuts the handle from the straight running state. .

For example, after the driver starts steering from a straight traveling state, when the driver feels the response of the steering wheel but does not feel the vehicle response, the vehicle response cannot be felt unless the steering wheel is further turned. A feeling of rigidity is bad, that is, a feeling of bending is felt. In such a case, the driver feels uneasy about the steering wheel operation, does not pass the course as intended at the time of lane change or cornering, further deviates from the lane at the corner, and can operate the steering wheel appropriately. Disappear.
On the other hand, when the steering wheel is cut from a straight state, the driver feels that the response of the steering wheel and the vehicle response are well balanced, that is, if the "rigidity" is good, the driver directly operates the steering wheel without bending. As a result, safety can be improved and a feeling of steering without anxiety can be felt.

The “stiffness” of “stiffness” is the value of the steering angle (steering force dead zone) when the driver feels steering force (responsiveness) after turning the steering wheel from the straight drive state, and then the driver The steering angle value (vehicle response dead zone) when the vehicle response (yaw rate or lateral G) is felt becomes good when the value becomes a constant value.
Also in this embodiment, the steering force feels the steering force 6N, the vehicle response feels the yaw rate is 0.4 deg / s, and the steering angle (steering response) is the steering angle that feels the steering response. The dead zone size is the steering angle (θ _A = 0.8 to 1.2 deg), and the dead zone size of the vehicle response, which is the steering angle at which the vehicle response is felt, is the steering angle (θ _B = 4.0 to 5.0 deg). By setting to, the driver feels a good “feeling of rigidity (feeling not to bend)”.
In the present embodiment, the steering force F and the yaw rate Y shown in FIG. 11 are set to the target steering of the second control unit 24 in FIG. 7 described above so that such “feeling of rigidity (feeling not to bend)” can be achieved. It is calculated by the force calculation unit 66 and the target vehicle response calculation unit 74 of the third control unit 28.
Specifically, as shown in FIG. 11, after the driver starts steering from the straight traveling state, the steering angle θ (when the steering force F (= F _A ) exceeds 6N (perception threshold of response) is determined. = Θ _A ), that is, the size of the dead zone of the steering force is in the range of 0.8 to 1.2 deg. Next, the steering angle θ (= θ _B ) when the yaw rate Y (= Y _B ) exceeds 0.4 deg / s (vehicle response perception threshold), that is, the size of the dead zone of the vehicle response is 4.0. It is ˜5.0 deg. In the present embodiment, the value of the steering angle θ _A that is the size of the dead zone of the steering force (response) and the value of the steering angle θ _B that is the size of the dead zone of the vehicle response are determined based on the vehicle speed and the steering speed. Even if the vehicle weight and / or the road surface state change, it is always set to a constant value (or a certain range).

Also in the present embodiment, the target steering force characteristic and / or the target vehicle response characteristic is controlled (corrected) to obtain the steering force dead zone θ _A and the vehicle response dead zone θ _B.
In the present embodiment, the value of the steering angle θ _A that is a dead zone of the steering force (response) and the value of the steering angle θ _B that is a dead zone of the vehicle response are determined based on the vehicle speed, the steering speed, the vehicle weight, and / or Or, even if the road surface condition changes, a desired steering feeling having a “stiff feeling” and “a feeling of bending” is set by always setting it to a constant value (or a certain range). I can.

The “stiffness” of “stiffness” means that when the driver cuts the steering wheel from a straight traveling state, the steering force when the lateral G of the vehicle becomes 0.1 G, for example, and the lateral G becomes 0.1 G to 0.1 G, for example. This is a steering feeling that is good when the amount of increase in steering force when increasing to 2G becomes a constant value.
As shown in FIG. 15, at the point C where the lateral acceleration (lateral G), which is the vehicle response, becomes 0.1 G, the steering force becomes the steering force F _{0.1 G. From} this point C, the lateral G becomes 0.2 G. The increase amount of the steering force up to the point D becomes a steering force increase amount ΔF _0.1-0.2G . Furthermore, the value of the steering force F _{0.1 G,} rather than perceived threshold of response described above (6N), and set to a large value (= 12~13N), the value of the steering force increment [Delta] F _0.1-0.2G is It is set to a value smaller than the value of the steering force F _0.1G (= 3~4N).
Note that the yaw rate may be used instead of the lateral G as a reference for the magnitude of the vehicle response.

In the present embodiment, the values of these “steering force F _0.1G ” and “steering force increase amount ΔF _0.1-0.2G ” are changed as the vehicle speed, the steering speed, the vehicle weight, and / or the road surface state change. However, it is possible to set a desired steering feeling having a “hard feeling” of “rigidity” by always setting to a constant value (or a certain range).

Next, referring to FIG. 17, “spring feeling” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described.
“Spring feeling” is a steering feeling that the driver feels when the steering wheel is returned by the force of the steering wheel itself when the steering wheel is turned from a straight traveling state and then the steering wheel is returned.
For example, when the driver pulls out the force applied to the steering wheel to return the steering wheel, if the steering force of the steering wheel itself is large, the steering wheel is greatly returned until the driver feels a change in steering force (returning the steering angle). The driver feels that the feeling of returning (spring feeling) is great. On the other hand, when the driver tries to return the steering wheel, if the feeling that the steering wheel is returned by the force of the steering wheel and the return amount of the steering angle that the driver expects is balanced appropriately, the driver The expected amount of return of the steering angle matches the feeling received from the steering wheel, and the feeling of spring is good.

According to the present embodiment, the “spring feeling” refers to the steering force when the driver cuts the steering wheel from the straight traveling state and then returns the steering wheel, regardless of changes in the vehicle speed, the steering speed, the vehicle weight, and / or the road surface state. However, when the steering force is reduced by a predetermined steering force value (6N) from the steering force when the steering wheel is returned, the steering angle is good when the steering angle returns from the maximum steering angle that is the steering angle when the steering wheel is returned by the predetermined steering angle value. Steering feeling.
Even if the maximum steering angle changes, it is desirable that the steering angle return ratio, which is a ratio of a predetermined steering angle value that is a return amount with respect to the maximum steering angle, is a constant ratio (10 to 20%).
According to the present embodiment, the relationship between the steering force and the steering angle is as shown in FIG. 16, and the steering angle θ is maximum at the point E, and becomes the steering force F _E and the steering angle θ _{E at the} point _E. Further, the steering force F _F and the steering angle become θ _{F at the} point F where the steering force F _E is decreased by 6N which is a predetermined steering force value.

Is 6N is a predetermined steering force values, a human can feel (which can be controlled) the value of the minimum force, when the handle returns, driver reduces steering force by 6N from the steering force F _E For the first time, I feel that the steering force has changed. In this embodiment, the return amount Δθ (= θ _E −θ _F ) of the steering angle when the steering wheel returns is always constant regardless of changes in the vehicle speed, steering speed, vehicle weight, and / or road surface condition. It is said.
In the present embodiment, even if the maximum steering angle changes, the steering angle return ratio (Δθ / θ _E ), which is a ratio of a predetermined steering angle value that is a return amount with respect to the maximum steering angle, is a constant ratio (10 ~ 20%).

In the present embodiment, the target steering force characteristic shown in FIG. 16 is set by the target steering force calculator 66 of the second controller 24 shown in FIG.
As described above, since the minimum value of the steering force change felt by the driver is 6N, the driver feels the steering force change only at a position where the steering force is reduced by 6N from the steering angle position of the maximum steering angle. If the reduction amount of the corner is the reduction amount expected by the driver, the driver can feel a good “spring feeling”. Therefore, in this embodiment, the amount of decrease in the steering angle is constant regardless of the vehicle speed, the steering speed, the vehicle weight, and / or the road surface condition, so that the driver feels a good “spring feeling”. Can do.

Next, with reference to FIG. 17, “disengagement feeling at the time of cutting” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described. FIG. 17 is a diagram showing a characteristic of the steering force with respect to the steering angle for explaining the “feeling of slipping off” of the steering feeling set according to the present embodiment.
“A feeling of disconnection at the time of cutting” is a steering feeling that the driver feels that the steering force is released when the driver cuts the steering wheel from a straight traveling state.

  Specifically, when the driver cuts the steering wheel from a straight traveling state, the steering force increases from the start of the steering of the steering wheel, and when the steering force exceeds a predetermined value, the steering force is reduced in order to reduce the driver's burden. The rate of increase is made smaller than before, but if the rate of increase of the steering force becomes too small, the driver feels that the steering amount of the steering wheel (steering amount) is not enough and cuts the steering wheel too much. Or extra correction steering is required without passing through the target course. On the other hand, if the amount of decrease in the rate of increase of the steering force is appropriate, the feeling that the steering force is lost becomes good, the safety is improved, and the driver can feel a steering feeling without anxiety.

  For this reason, in the present embodiment, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher so that the driver feels good “feeling of slipping off”, the vehicle speed, the steering speed, the vehicle weight, and / or Regardless of the change in the road surface condition, the ratio of the increase in the steering force to the increase in the steering angle in the on-center region from the start of the turning of the steering wheel to the predetermined steering force, and the off-center region in which the predetermined steering force is exceeded The target steering force characteristic and / or the target vehicle response characteristic is controlled so that the ratio of the increase in the steering force with respect to the increase in the steering angle is within a predetermined ratio range (0.3 to 0.5). Yes.

More specifically, as shown in FIG. 17, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher, from the start of the steering of the steering wheel until a predetermined steering force (9N) shown as point G in FIG. In the on-center region, the rate of increase of the steering force with respect to the steering angle (the rate of increase of the steering force in the on-center region) increases almost linearly with a predetermined magnitude, and in the off-center region where the steering force is greater than the predetermined steering force (9N). The increase rate of the steering force with respect to the steering angle (the increase rate of the steering force in the off-center region) also increases almost linearly, but is smaller than that in the on-center region.
Here, in this embodiment, the steering force increase ratio ratio ((steering force increase ratio in the off-center area) / (steering force increase ratio in the on-center area) is set to be 0.3 to 0.5. Yes.

In this embodiment, the target steering force characteristics shown in FIG. 17, that is, the steering force increase rate in the on-center region, the steering force increase rate in the off-center region, the predetermined steering force (9N), and the predetermined steering force increase rate ratio (0. 3 to 0.5) is set by the target steering force calculation unit 66 of the second control unit 24 shown in FIG. 7, but the target steering force calculation unit 66 of the second control unit 24 of FIG. The target steering force characteristic and the target vehicle response characteristic may be set by both of the target vehicle response calculation unit 74 of the third control unit 28, and the target steering force characteristic of FIG.
According to the present embodiment, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher, the steering force increase rate ratio is always set in this way regardless of changes in the vehicle speed, the steering speed, the vehicle weight, and / or the road surface state. By setting the range to a predetermined ratio, a desired steering feeling (DNA steering feeling) can be obtained with respect to “feeling of slipping when cutting”.

Next, referring to FIG. 18, the “disengagement feeling at the time of return” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described. FIG. 18 is a diagram showing the characteristic of the steering force with respect to the steering angle for explaining the “feeling of slipping off at the time of return” of the steering feeling set according to the present embodiment.
“A feeling of slipping when returning” is a steering feeling that the driver feels that the steering force is released when the driver cuts the steering wheel from the straight traveling state and then returns the steering wheel.
Specifically, when the driver cuts the steering wheel from a straight state and then returns the steering wheel, the steering force decreases from the start of the return of the steering wheel, and when the steering force becomes a predetermined value or less, the rate of decrease in the steering force However, if the rate of decrease in the steering force is increased too much, the driver feels that the steering wheel has already been fully returned and the steering wheel is delayed to return to the target course. Unnecessary correction steering is necessary. On the other hand, if the magnitude of the reduction ratio of the steering force is appropriate, the feeling that the steering force is lost is good, and good steering can be performed.

  For this reason, in this embodiment, in order for the driver to feel a good "feeling of slipping off when returning", when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the vehicle speed, the steering speed, Regardless of the change in vehicle weight and / or road surface condition, the ratio of the decrease in steering force to the decrease in steering angle in the off-center region from the start of the return of the steering wheel to the predetermined steering force, and the predetermined steering force The target steering force characteristic and / or the target vehicle response characteristic so that the ratio of the decrease in the steering force with respect to the decrease in the steering angle in the on-center region as described below falls within a predetermined ratio range (0.5 to 0.7). To control.

Specifically, as shown in FIG. 18, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, a predetermined steering force indicated by point H in FIG. In the off-center region up to (6N), the rate of decrease of the steering force with respect to the steering angle (the steering force decrease rate of the off-center region) decreases almost linearly with a predetermined magnitude, and the predetermined steering force (6N) In the on-center region, the rate of decrease in steering force relative to the decrease in steering angle (the rate of decrease in steering force in the on-center region) also decreases almost linearly, but compared to the rate of decrease in steering force in the off-center region, It is getting bigger.
Here, in the present embodiment, the steering force reduction rate ratio ((steering force reduction rate in the off-center region) / (steering force reduction rate in the on-center region)) is set to be 0.5 to 0.7. Yes.

  In the present embodiment, the target steering force characteristics shown in FIG. 18, that is, the off-center region steering force reduction rate, the on-center region steering force reduction rate, the predetermined steering force (6N), and the predetermined steering force reduction rate ratio (0. 5 to 0.7) is set by the target steering force calculation unit 66 of the second control unit 24 shown in FIG. 7, but the target steering force calculation unit 66 of the second control unit 24 of FIG. The target steering force characteristic and the target vehicle response characteristic may be set by both of the target vehicle response calculation unit 74 of the third control unit 28, and the target steering force characteristic of FIG.

  According to this embodiment, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the steering force is always maintained regardless of changes in the vehicle speed, the steering speed, the vehicle weight, and / or the road surface state. By setting the reduction ratio ratio within the predetermined ratio range as described above, it is possible to obtain a desired steering feeling (DNA steering feeling) with respect to the “feeling of slipping when returning”.

Next, with reference to FIG. 19, “elongation of vehicle response” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described. FIG. 19 is a diagram showing a characteristic of a vehicle response (yaw rate) with respect to a steering force for explaining “elongation of vehicle response” of the steering feeling set according to the present embodiment.
“Elongation of vehicle response” is a steering feeling that the driver feels when the vehicle response such as the yaw rate increases as the steering force increases when the steering wheel is turned from the straight traveling state.

  Specifically, when the driver cuts the steering wheel from a straight traveling state, the vehicle response such as the steering force and the yaw rate increases from the start of the steering of the steering wheel, and when the steering force exceeds a predetermined value, the driver's burden is reduced. Therefore, the rate of increase in steering force is smaller than before, but the rate of increase in vehicle response such as yaw rate with respect to the rate of increase in steering force increases. At this time, if the rate of increase in vehicle response is larger or smaller than the driver's expected value, or if the vehicle response increases regardless of the steering force, the driver will not be able to steer the intended steering wheel and will not be able to pass the intended course. Extra correction steering is required. On the other hand, if the rate of increase in vehicle response is appropriate, it will match the driver's expectations, feel good vehicle response growth, improve safety, and the driver will feel a sense of steering without anxiety. Can do.

  For this reason, in the present embodiment, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher in order to feel a good "elongation of vehicle response", the vehicle speed, the steering speed, the vehicle weight, and / or Regardless of the change in road surface condition, the rate of increase in vehicle response such as yaw rate with respect to the increase in steering force in the on-center region from the start of turning of the steering wheel to the predetermined steering force, and the off-center exceeding the predetermined steering force. The target steering force characteristic and / or the target vehicle response characteristic is controlled so that the ratio of the increase in the vehicle response to the increase in the steering force in the region falls within a predetermined ratio range (2.0 to 5.0). I have to.

Specifically, as shown in FIG. 19, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher, from the start of the steering of the steering wheel until a predetermined steering force (9N) shown as point G in FIG. In the on-center region, the rate of increase in the yaw rate (vehicle response) with respect to the steering force (the vehicle response increase rate in the on-center region) increases almost linearly at a predetermined magnitude and becomes equal to or greater than the predetermined steering force (9N). In the off-center region, the rate of increase in the yaw rate (vehicle response) with respect to the steering force (the vehicle response increase rate in the off-center region) also increases almost linearly, but is larger than that in the on-center region.
Here, in the present embodiment, the vehicle response increase rate ratio which is (the vehicle response increase rate in the off-center region) / (the vehicle response increase rate in the on-center region) is set to be 2.0 to 5.0. Yes.

In this embodiment, the target steering force characteristics shown in FIG. 19, that is, the vehicle response increase rate in the on-center region, the vehicle response increase rate in the off-center region, the predetermined steering force (9N), and the predetermined vehicle response increase rate ratio (2. 0 to 5.0) by the target steering force calculation unit 66 of the second control unit 24 and / or the target vehicle response calculation unit 74 of the third control unit 28 shown in FIG. Response characteristics are set, and from these, the target steering force characteristics of FIG. 19 are set.
Here, in the present embodiment, the value of the predetermined steering force (point G in FIG. 19) that is the boundary between the on-center region and the off-center region is 9N, and the predetermined steering force (“cutting feeling”) (see FIG. 17). (G point) of (9N). As a result, when the driver cuts the steering wheel from a straight traveling state exceeding a predetermined vehicle speed, the driver always has the same timing as “feeling of slipping (cutting)” regardless of changes in the vehicle speed, steering speed, vehicle weight, and / or road surface condition. As for “elongation of vehicle response”, a desired steering feeling (DNA steering feeling) can be obtained. In the present embodiment, the point G in FIG. 17 and the point G in FIG. 19 may be set at different timings.
In FIG. 19, the value of the yaw rate is used as the vehicle response, but the lateral acceleration (lateral G) may be used.

  According to the present embodiment, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher, the vehicle response increase rate ratio is always set in this way regardless of changes in the vehicle speed, steering speed, vehicle weight, and / or road surface condition. By setting the range to a predetermined ratio, a desired steering feeling (DNA steering feeling) can be obtained with respect to “elongation of vehicle response”.

Next, with reference to FIG. 20, “trackability of vehicle response” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) will be described. FIG. 20 is a diagram showing the characteristics of the yaw rate (vehicle response) with respect to the steering force for explaining the “following performance of the vehicle response” of the steering feeling set according to the present embodiment.
“Vehicle response tracking” means that when the driver cuts the steering wheel from a straight-ahead state and then returns the steering wheel, the steering force decreases from the start of the steering wheel return, but the vehicle response increases. This is the steering feeling that is felt when the vehicle response decreases as the steering force decreases.

  Specifically, when the driver cuts the steering wheel from a straight state and then returns the steering wheel, when the steering force decreases from the start of the steering wheel return but the vehicle response increases, the relationship between the steering force and the vehicle response is reversed. Therefore, the driver feels that the following performance of the vehicle response (yaw or lateral G) is poor. Furthermore, when the steering force decreases and the steering force becomes a predetermined value or less, the rate of decrease in vehicle response is made smaller than before, but the rate of decrease in vehicle response is the driver's expectation. If the value is larger or smaller than the value, the driver cannot steer the steering wheel as intended, and an extra correction steering is required without passing through the target course. On the other hand, if the time in which the steering force and the vehicle response are in an inverse relationship is short, the steering feeling is good, and if the rate of decrease in the vehicle response is appropriate, it matches the driver's expectation value and the vehicle is good. You can feel the response following, and as a result, the safety is improved and you can feel the steering feeling without anxiety.

  For this reason, in this embodiment, in order for the driver to feel good `` following response of the vehicle response '', when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the vehicle speed, the steering speed, Steering from the beginning of steering wheel return in the steering wheel half cycle (until turning the steering wheel from the neutral position and then back to the neutral position) regardless of changes in vehicle weight and / or road surface conditions Next, the predetermined time from the start of the return of the steering wheel is set so that the time during which the force decreases but the vehicle response increases is within a predetermined range (20%) with respect to the half cycle time of the steering of the steering wheel. The rate of decrease in vehicle response to the decrease in steering force in the off-center region until the steering force is reached, and the steering force in the on-center region that is less than or equal to the predetermined steering force And rate of decrease of the vehicle response to decrease, so that the range of a predetermined ratio (1.5 to 2.5), so as to control the target steering force characteristic and / or target vehicle response characteristics.

Specifically, as shown in FIG. 20, first, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, steering is started from the start of steering wheel return (point I in FIG. 20). The time (yaw rate increasing time after returning the steering wheel) in which the force decreases but the vehicle response increases (yaw rate increasing time after returning the steering wheel) is a region where the steering feeling is poor, so it is desirable that the time is short. Therefore, in the present embodiment, the target steering force characteristic and / or the target vehicle response is set so that the yaw rate increase time after returning the steering wheel is equal to or less than a predetermined ratio (20%) with respect to the steering wheel half cycle time. Controls the characteristics. Next, in the off-center region until the predetermined steering force (6N) shown as point H in FIG. 20 is reached, the rate of decrease in vehicle response to the steering force (vehicle response decrease rate in the off-center region) is a predetermined magnitude. In the on-center region where the steering force decreases to a predetermined steering force (6N) or less, the rate of decrease in vehicle response to the decrease in steering force (vehicle response decrease rate in the on-center region) also decreases substantially linearly. This is smaller than the rate of decrease in the steering force in the off-center region.
Here, in the present embodiment, the vehicle response decrease rate ratio ((off-center region vehicle response decrease rate) / (on-center region vehicle response decrease rate)) is set to 1.5 to 2.5. Yes.

In this embodiment, the target steering force characteristics shown in FIG. 20, that is, the yaw rate increase time after returning the steering wheel, the vehicle response decrease rate in the off-center region, the vehicle response decrease rate in the on-center region, a predetermined steering force (6N), a predetermined The vehicle response decrease ratio ratio (1.5 to 2.5) is set by the target steering force calculation unit 66 of the second control unit 24 shown in FIG. The target steering force characteristic and the target vehicle response characteristic are set by both the target steering force calculation unit 66 and the target vehicle response calculation unit 74 of the third control unit 28, and from these, the target steering force characteristic of FIG. 20 is set. Anyway.
Here, in this embodiment, the value of a predetermined steering force (point H in FIG. 20) that is the boundary between the on-center region and the off-center region is 6N, and the predetermined steering force in the “disengagement feeling (return)” (FIG. 18). The value is the same as the value (6N) of point H). As a result, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the driver always feels “disengagement (returning back) regardless of changes in vehicle speed, steering speed, vehicle weight, and / or road surface condition. ) ", The desired steering feeling (DNA steering feeling) can be obtained with respect to" vehicle response followability ". In the present embodiment, the point H in FIG. 18 and the point H in FIG. 20 may be set at different timings.
In FIG. 20, although the yaw rate value is used as the vehicle response, lateral acceleration (lateral G) may be used.

  According to this embodiment, when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the vehicle response is always performed regardless of changes in the vehicle speed, steering speed, vehicle weight, and / or road surface condition. By setting the reduction ratio ratio in the range of the predetermined ratio in this way, a desired steering feeling (DNA steering feeling) can be obtained with respect to “vehicle response followability”.

  As described above, in this embodiment, “steering force / play feeling of vehicle response”, “rigidity”, “spring feeling”, “disengagement feeling when cutting”, “disengagement feeling when returning”, “vehicle response” The desired steering feeling (DNA steering feeling) is quantified according to the seven indicators of “elongation of the vehicle” and “trackability of vehicle response” or for each of these indicators or a combination of each of the indicators. The steering feeling (DNA steering feeling) is set, but among these seven indicators, the most important in setting the desired steering feeling is “stiffness”, and the next most important is “Steering force / vehicle response play”.

  For this reason, in this embodiment, a substantially constant desired steering feeling (DNA steering feeling) can be controlled regardless of changes in “vehicle speed”, “steering speed”, “vehicle weight” and / or “road surface condition”. Alternatively, when the setting is mechanically, when the control becomes complicated or the mechanical setting is difficult, based on at least one index of “stiffness”, or at least “stiffness” and “steering force / A desired steering feeling (DNA steering feeling) may be set on the basis of two indicators of “a feeling of play of vehicle response”.

In the present embodiment described above, the target steering force characteristic and the target vehicle response characteristic for obtaining a desired steering feeling (DNA steering feeling) are respectively obtained by the second control unit 24 and the third control unit 28 shown in FIG. Although this is calculated and calculated, the present embodiment is not limited to such a control that creates a desired steering feeling as described above, and a desired steering feeling may be created mechanically.
Specifically, when setting the target steering force characteristic, the control characteristic of the electric power steering apparatus is set, and when setting the target vehicle response characteristic, the transmission ratio R of the VGR apparatus is set to a desired value. In addition, the tire characteristics and the alignment change characteristics of the wheel suspension device may be set to desired values.

  Thus, when mechanically creating a desired steering feeling, it is difficult to satisfy all of the above seven indicators. In this case, only the most important “stiffness” indicator is used. Further, if possible, it is preferable to satisfy two indexes of “feel of rigidity” and “play feeling of steering force / vehicle response”.

  Furthermore, when a desired steering feeling is mechanically created, it is possible to set substantially the same desired steering feeling for all changes in vehicle speed, steering speed, vehicle weight, and road surface condition. If difficult, at least the same desired steering feeling may be set only for changes in vehicle speed. Further, as much as possible, the same desired steering feeling may be set for any one or a plurality of changes in the steering speed other than the vehicle speed, the vehicle weight, or the road surface condition.

It is a perspective view which shows an example of the electric power steering device of the motor vehicle to which this invention is applied. It is a whole lineblock diagram showing the VGR device by the embodiment of the present invention. It is the partial side view seen along the III-III line of FIG. It is the partial side view seen along the IV-IV line of FIG. It is a figure which shows a steering force characteristic model. It is a figure which shows the spring component, the viscosity component, and the friction component in the steering force characteristic model of FIG. It is a block diagram which shows the control unit of the steering feeling setting apparatus of the motor vehicle by embodiment of this invention. It is a correction map of the proportional gain of the 1st control part and the 2nd control part of the control unit shown in FIG. It is a diagram which shows the transmission ratio R in the non-center feel sensitive area of a VGR apparatus. 5 is a control flow for setting a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention. It is a diagram which shows the steering force F, the steering angle (theta), and the yaw rate Y in the desired steering feeling (DNA steering feeling) of the base set by embodiment of this invention. It is a diagram for explaining the setting of the steering feeling according to the present embodiment when the vehicle speed increases from the base. It is a diagram for explaining the setting of the steering feeling according to the present embodiment when the steering speed is increased from the base. 7 shows a control flow for making a setting relating to “steering force / play feeling of vehicle response” of a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention. FIG. 5 is a diagram for explaining “stiffness” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention. It is a diagram for explaining “spring feeling” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention. FIG. 5 is a diagram for explaining a “feeling of missing when cutting”, which is one of the indexes for setting a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention. FIG. 5 is a diagram for explaining a “feeling of falling out” that is one of the indexes for setting a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention. It is a diagram for explaining “elongation of vehicle response” which is one of the indexes for setting a desired steering feeling (DNA steering feeling) according to the embodiment of the present invention. FIG. 3 is a diagram for explaining “trackability of vehicle response”, which is one of indices for setting a desired steering feeling (DNA steering feeling) according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power steering device 2 Handle 4 Steering shaft 8 VGR device 16 Tire (wheel)
18 Electric motor 20 Control unit 22 1st control part (normal assist control part)
24 Second Control Unit (Center Feel Control Unit)
26 Motor current control unit 28 Third control unit (vehicle response control unit)
30 Stepping Motor 50 Torque Sensor 52 Lateral G Sensor 54 Vehicle Speed Sensor 56 Steering Angle Sensor 58 Yaw Rate Sensor 60 Vehicle Weight Sensor 62 Road Surface μ Sensor 66 Target Steering Force Calculation Unit 74 Target Vehicle Response Calculation Unit 76 Output Signal Generation Unit 78 Motor Rotation Angle Sensor

Claims (6)

Steering force characteristic control means for controlling the steering force characteristic;
Vehicle response characteristic control means for controlling the vehicle response characteristic of the vehicle;
Steering feeling setting means for setting a desired steering feeling,
When the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the steering feeling setting means always starts from the return of the steering wheel until the predetermined steering force is reached regardless of the change in the vehicle speed. The ratio of the decrease in vehicle response to the decrease in the steering force in the off-center region and the ratio of the decrease in vehicle response to the decrease in the steering force in the on-center region that is equal to or less than the predetermined steering force are within a predetermined ratio range. A steering feeling setting device for an automobile, which is configured to control the steering force control means and / or the vehicle response characteristic control means.   The steering feeling setting means is configured such that when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the steering wheel is always returned regardless of changes in steering speed, vehicle weight, and / or road surface condition. The rate of decrease in vehicle response to a decrease in steering force in the off-center region from the start of the vehicle to a predetermined steering force, and the rate of decrease in vehicle response to a decrease in steering force in the on-center region that is equal to or less than the predetermined steering force 2. The steering feeling setting device for an automobile according to claim 1, wherein the steering force control means and / or the vehicle response characteristic control means are controlled so that the value falls within a predetermined ratio range.   The ratio of the decrease in the vehicle response to the decrease in the steering force in the off-center region with respect to the decrease in the vehicle response to the decrease in the steering force in the on-center region is in the range of 1.5 to 2.5. Item 3. A steering feeling setting device for an automobile according to Item 2.   The steering force feeling setting means is configured such that when the driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher and then returns the steering wheel, the time for the steering force to decrease and the vehicle response to increase from the start of the steering wheel return The automobile according to any one of claims 1 to 3, wherein the steering force control means and / or the vehicle response characteristic control means are controlled so as to be within a predetermined ratio with respect to a half cycle time of steering. Steering feeling setting device.   5. The predetermined range is such that the time during which the steering force decreases and the vehicle response increases from the start of the return of the steering wheel is 0.2 or less with respect to the half-cycle time of the steering wheel. A steering feeling setting device for an automobile according to the item.   An automotive steering feeling setting device for setting a desired steering feeling, a steering force characteristic setting means for setting a predetermined target steering force characteristic, and a vehicle response characteristic setting means for setting a predetermined target vehicle response characteristic The steering force characteristic setting means and the vehicle response characteristic setting means have the target steering force characteristic and the target vehicle response characteristic. The driver cuts the steering wheel from a straight traveling state at a predetermined vehicle speed or higher, and then returns the steering wheel. When the vehicle speed, the steering speed, the vehicle weight and / or the road surface condition change, the rate of decrease in the vehicle response to the decrease in the steering force in the off-center region from the start of the return of the steering wheel until the predetermined steering force is obtained. The ratio of the decrease in vehicle response to the decrease in steering force in the on-center region that is equal to or less than the predetermined steering force is within a predetermined ratio range. To an automobile steering feeling setting device, characterized in that set.

Images