JP2006193083A - Steering control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering control device for a vehicle capable of reflecting a delay in a steering actuator caused by an inputted load and further capable of realizing an application of a steering reaction force corresponding to its original steering state. <P>SOLUTION: This steering control device for a vehicle comprises a front wheel steering angle estimation model block 107 for estimating a front wheel steering angle in response to a desired steering angle θ<SB>h</SB>and a response characteristic of a front wheel steering actuator 102, a steering angle sensor for detecting an actual front wheel steering angle θ<SB>p</SB>, and a steering reaction force correcting means (a gain block 112 and adding block 114) for the more correcting the desired steering reaction force F, the larger the difference between an estimated steering angle θ<SB>t</SB>and the actual front wheel steering angle θ<SB>p</SB>is. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a steering actuator that steers steered wheels according to the steering state of the steering unit, and a steering reaction force actuator that applies a steering reaction force to the steering unit according to the steered state of the steered wheels. Belongs to the technical field of steering control devices for vehicles.

In the conventional vehicle steering control device, when the deviation between the target turning angle of the steered wheel and the actual turning angle exceeds a predetermined value, a steering reaction force is applied to the steering wheel, thereby The followability is appropriate for the operation of the handle (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 10-324261

  However, in the above prior art, since the steering reaction force is applied in a state where the normal response delay of the steering actuator and the delay due to the input load are mixed, the steering reaction force corresponding to the original steering state is applied. There was a problem that could not be given. For example, when the deviation is increased, a steering reaction force corresponding to the input load is not applied when the input load is increased, and conversely, when the input load is decreased, a steering reaction force may be applied more than necessary. there were.

  The present invention has been made by paying attention to the above-mentioned problem, and the object of the present invention is to reflect the delay of the steering actuator due to the input load in the steering reaction force, and to perform the steering corresponding to the original steering state. An object of the present invention is to provide a vehicle steering control device capable of providing a reaction force.

In order to achieve the above object, the present invention provides:
A steered actuator for steering the steered wheels and a target steered angle corresponding to the steering state of the steering unit operated by the driver are set, and the steered actuator is driven and controlled so as to coincide with the target steered angle. And a steering reaction force command value corresponding to the steering state of the steered wheel is set, and the steering reaction force command value is set to the steering reaction force command value. A steering reaction control means for driving the steering reaction force actuator based on the steering reaction force control means,
Based on the target turning angle and the response characteristic of the turning actuator, a turning angle estimation means for estimating the turning angle of the steered wheel;
An actual turning angle detection means for detecting an actual turning angle of the steering wheel;
Steering reaction force correcting means for correcting the steering reaction force command value to be larger as the deviation between the estimated turning angle and the actual turning angle is larger;
It is characterized by providing.

  In the present invention, the steering reaction force is applied according to the deviation between the estimated turning angle based on the response characteristic of the turning actuator and the actual turning angle. Therefore, it is possible to realize the application of the steering reaction force corresponding to the original steered state.

  Hereinafter, the best mode for carrying out the present invention will be described based on Examples 1 and 2.

First, the configuration will be described.
FIG. 1 is an overall system diagram illustrating a vehicle steering control device according to a first embodiment. The vehicle steering control device according to the first embodiment includes (1) a steering unit, (2) a backup device, (3) a steering unit, (4) Consists of a controller.

(1) Steering unit The steering unit includes a steering angle sensor 1, an encoder 2, torque sensors 3 and 3, and a steering reaction force actuator 5.

  The rudder angle sensor 1 is a means for detecting an operation angle of the handle 6 and is provided on a column shaft 8 a that couples a clutch 9 and a handle 6 described later. That is, the rudder angle sensor 1 is installed between the steering wheel 6 and the torque sensors 3 and 3 and can detect the steering angle without being affected by an angle change caused by the twist of the torque sensors 3 and 3. ing. The rudder angle sensor 1 uses an absolute resolver or the like. The torque sensors 3 and 3 form a double system, and are installed between the steering angle sensor 1 and the steering reaction force actuator 5.

  The steering reaction force actuator 5 is a reaction force actuator that applies a reaction force to the handle 6. The steering reaction force actuator 5 is composed of a 1-rotor 1-stator electric motor having a column shaft 8a as a rotation axis, and its casing is fixed at an appropriate position on the vehicle body. Has been. As the steering reaction force actuator 5, a brushless motor is used, and an encoder 2 and a Hall IC (not shown) are added as the brushless motor is used. In that case, motor drive that generates motor torque is possible with only the Hall IC, but fine torque fluctuations occur and the feeling of steering reaction force is poor. Therefore, in order to perform more delicate and smooth reaction force control, the encoder 2 is mounted on the column shaft 8a, and motor control is performed to reduce minute torque fluctuations and improve the feeling of steering reaction force. Yes. A resolver may be used instead of the encoder 2.

(2) Backup device The backup device includes a cable column 7 and a clutch 9.
The clutch 9 is interposed between the column shaft 8a and the pulley shaft 8b. In the first embodiment, an electromagnetic clutch is used. When the clutch 9 is engaged, a column shaft 8a as an input shaft and a pulley shaft 8b as an output shaft are connected, and the steering torque applied to the handle 6 is mechanically transmitted to the steering mechanism 15. .

  The cable column 7 is a column that transmits torque while avoiding interference with a member interposed between the steering portion (1) and the steered portion (3) in the backup mode in which the clutch 9 is engaged. It is a mechanical backup mechanism that demonstrates the shaft function. The cable column 7 winds two inner cables whose ends are fixed to the two reels in opposite directions, and fixes both ends of the outer tube in which the two inner cables are inserted into the two reel cases. It is constituted by.

(3) Steering unit The steering unit includes an encoder 10, a steering angle sensor (actual steering angle detection means) 11, torque sensors 12, 12, front wheel steering actuators 14, 14, steering mechanism 15 and steered wheels 16, 16.

  The rudder angle sensor 11 and the torque sensors 12, 12 are provided on an axis of a pinion shaft 17 in which a pulley of the cable column 7 is attached to one end and a pinion gear is formed at the other end. As the rudder angle sensor 11, an absolute resolver or the like that detects the rotational speed of the shaft is used. Further, as the torque sensors 12 and 12, a sensor that forms a double system like the torque sensors 3 and 3 and detects torque by a change in inductance is used. The steering angle sensor 11 is arranged on the cable column 7 side, and the torque sensors 12 and 12 are arranged on the steering mechanism 15 side, so that the angle due to the torsion of the torque sensors 12 and 12 when the steering angle is detected by the steering angle sensor 11. We are not affected by changes.

  The front wheel steering actuators 14 and 14 are provided with pinion gears engaged with worm gears provided at intermediate positions between the steering angle sensor 11 and the torque sensors 12 and 12 of the pinion shaft 17 on the respective motor shafts, so that the pinion shaft 17 is driven when the motor is driven. It is comprised so that steering torque may be provided to. As with the steering reaction force actuator 5, the front wheel steering actuators 14 and 14 add an encoder 10 and a Hall IC (not shown) as the brushless motor is used.

  The steering mechanism 15 is a steering mechanism that steers the left and right front wheels (steering wheels) 16 and 16 by rotation of the pinion shaft 17, and a rack gear that is inserted into the rack tube 15 a and meshes with the pinion gear of the pinion shaft 17. The formed rack shaft 15b, the tie rods 15c, 15c coupled to both ends of the rack shaft 15b extending in the left-right direction of the vehicle, one end coupled to the tie rods 15c, 15c, and the other end coupled to the front wheels 16, 16 And knuckle arms 15d and 15d.

(4) Control controller The control controller has a dual system composed of two control controllers 19 and 19 that perform processing operations and the like. The control controller 19 includes a steering angle sensor 1, an encoder 2, torque sensors 3 and 3, a Hall IC, a steering section encoder 10, a steering angle sensor 11, torque sensors 12 and 12, a Hall IC, and a vehicle speed sensor. The detection value from 20 is input.

  FIG. 2 is a system block diagram of the controller 19, and the controller 19 includes a front wheel steering controller (steering control means) 19a and a steering reaction force controller (steering reaction force control means) 19b. .

The front wheel steering control unit 19a inputs the actual steering angle θ _p of the front wheels 16 and 16 detected by the steering angle sensor 11 and the target steering angle θ _h calculated by the steering reaction force control unit 19b, and outputs the command current I _s and the estimated turning angle theta _t of the front wheels turning actuator 10.

The steering reaction force control unit 19b includes the steering angle θ _H of the handle 6 detected by the steering angle sensor 1, the actual steering angle θ _p of the front wheels 16 and 16 detected by the steering angle sensor 11, and the front wheel steering control. the estimated turning angle theta _t calculated by the parts 19a, inputs the vehicle speed, and outputs the command current I _r of the steering reaction force actuator 5, and a target steered angle theta _h.

Next, the operation will be described.
[Front wheel steering and steering reaction force control method]
The front wheel steering control and steering reaction force control method of the first embodiment will be described with reference to the control block diagram of FIG.

(Front wheel steering control)
When the steering angle θ _H of the steering wheel 6 is detected by the steering angle sensor 1, the steering reaction force control unit 10b determines the target turning angle θ from the steering angle θ _H and the variable gear ratio G0 set according to the vehicle speed. _h (= G0 * θ _H ) is obtained (variable gear ratio block 100).

Steering reaction force control unit 19b sends the target steering angle theta _h to the front wheels steering control unit 19a, converts the command current I _s for the corresponding motor drive in the front wheels steering control unit 19a (the current conversion on the block 101), by giving the command current I _s of the front wheel steering actuator to the motor to steer the front wheels 16, 16 (front wheel turning actuator block 102). The variable gear ratio G0 is set so as to decrease as the vehicle speed increases, and both good handling in the low speed range and stability of straight traveling in the high speed range are achieved.

(Steering reaction force control)
The steering reaction force control unit 19b calculates a steering reaction force K _p * θ _h corresponding to the reaction force characteristic of the steering angle of the steering system based on the calculated target turning angle θ _h (gain block 103). Further, the steering reaction force K _d * dθ _h / dt corresponding to the reaction force characteristic of the steering angular velocity of the steering system is obtained from the target turning angular velocity dθ _h / dt obtained by differentiating the target turning angle θ _h (derivative block 104). Calculate (gain block 105). These _{K p * θ h, K d} * dθ h / dt is added (addition block 106), the steering reaction force Fs of the steering input frequency is calculated.

Actual turning angle theta _p of the front wheels 16, 16 from becoming the command current I _s corresponding to the target turning angle theta _h a controlled object and outputs the actual turning angle theta _p from the front wheel turning actuator as input , The front wheel turning angle is estimated by modeling it as a transfer function G (s) of “command current I _s −actual turning angle θ _p ” (front wheel turning angle estimation model block 107; turning angle estimation means) ).

Since the front wheel turning angle estimation model G (s) can be approximated by a secondary delay,
G (s) = B / (s ² + As)
To determine the actual turning angle θ _p with respect to the command current Is.
Here, A and B are values set according to the front wheel turning actuator response characteristics, and the setting of the values of A and B is for detecting all loads input from the vehicle to the front wheel turning actuator. In other words, the transmission gain in the no-load state is used in order to provide a zero reference for providing polarity on the side that suppresses the response of the actuator and the side that assists.

The estimated turning angle theta _t calculated from the front wheel steering angle estimation model G (s), the deviation between the target steered angle theta _h calculated (subtraction block 108), with respect to the deviation has a characteristic shown in FIG. 4 Using the reaction force gain αg, a steering reaction force corresponding to the actuator response delay (steering reaction force corresponding to the actuator response) Fa based on the turning angle deviation is obtained (gain block 109) and added to the steering reaction force Fs corresponding to the steering input. (Addition block 110).
Fa = αg * (θ _h −θ _t )
Here, the reaction force gain αg is set by the magnitude of the steering reaction force for transmitting the front wheel turning actuator response delay to the driver. By the gain block 109 and summation block 110, as the deviation between the target steered angle theta _h and the estimated turning angle theta _t is large, a steering reaction force Fa of the actuator response component is increased, the target steering reaction force F largely corrected Steering reaction force correcting means is configured.

FIG. 5 shows a steering reaction force characteristic obtained by adding the steady component of the steering reaction force Fa corresponding to the actuator response to the steering reaction force K _p * θ _{h corresponding} to the steady steering input. As a result, a steering reaction force corresponding to a steady response delay of the front wheel steering actuator can be applied to the handle 6. In FIG. 5, the amount of addition of the steering reaction force increases as the target turning angle θ _h increases, but this is an example, and the amount of addition of the steering reaction force with respect to the target turning angle θ _h is Change.

On the other hand, with respect to the deviation (subtraction block 111) of the estimated turning angle theta _t calculated from the front wheel steering angle estimation model G (s) and the actual turning angle theta _p, the reaction force gain having the characteristics shown in FIG. 6 alpha ' Using g, a steering reaction force corresponding to a steady input load to the front wheel steering actuator is calculated (gain block 112). Here, the reaction force gain α'g is set to be larger in proportion to the deviation between the estimated turning angle theta _t and the actual turning angle theta _p.
Fb = α′g * (θ _h −θ _t )

By adding the steering reaction force Fb corresponding to the steady load input to Fs + Fa (addition block 114), the steady input load to the front wheel steering actuator is reflected in the steering reaction force as shown in FIG. Can do. The gain block 112, as the deviation between the estimated turning angle theta _t and the actual turning angle theta _p is large, by increasing the steering reaction force Fb of the load input frequency, the target steering reaction force F larger correction steering reaction force correction Means are configured.

Target steering reaction force calculated by the process (the steering reaction force command value) F (= Fs + Fa + Fb) the steering reaction force converted into the command current I _r for the corresponding motor drive by the control unit 19b (current transformation block 119) on the, by giving a command current I _r to steering reaction force actuator motor, adds a steering reaction force to the steering wheel 6 (the steering reaction force actuator block 120).

[Front wheel steering and steering reaction force control processing]
FIG. 8 is a flowchart showing a flow of front wheel steering and steering reaction force control processing executed by the control controller 19 of the first embodiment. Each step will be described below.

In step S1, the steering angle θ _H of the steering wheel 1 is calculated from the signal of the steering angle sensor 1, and the process proceeds to step S2.

  In step S2, the vehicle speed V is calculated from the signal from the vehicle speed sensor 20, and the process proceeds to step S3.

In step S3, it sets the variable gear ratio G0 and a vehicle speed V calculated by the steering angle theta _H and Step S2 calculated in step S1, with reference to the preset variable gear ratio map MAP (v), step S4 Migrate to

In step S4, the variable gear ratio G0 Metropolitan set by the steering angle theta _H and step S3 calculated in step S1, to calculate the target turning angle theta _h of the front wheels 16, 16 on the basis of the following equation, to step S5 Transition.
θ _h = G0 * θ _H

In step S5, the target turning angular velocity V _H is calculated from the target turning angle θ _h calculated in step S4 using the following formula, and the process proceeds to step S6.
V _H = (θ _h (t) −θ _h (t-1)) / dt

In step S6, the steering reaction force Fs for the steering input is calculated from the following equation, and the process proceeds to step S6.
_{Fs = K p * θ h (} t) + K d * (θ h (t) -θ h (t-1)) / dt

In step S7, the command current I _s (t) of the front wheel steering actuator 10 is calculated based on the following formula, and the process proceeds to step S8.
I _s (t) = P * θ _h (t) + I * ((θ _h (t) + θ _h (t−1)) / 2) + D * (θ _h (t) −θ _h (t−1))
Here, P, I, and D are predetermined proportional conversion values, integral conversion values, and differential conversion values.

In step S8, since the calculated command current I _s (t) transfer function G (s) and in step S7, the estimated target steering angle theta _h using the following formula, the process proceeds to step S9.
θ _t = G (s) * I _s (t)

In step S9, the target turning angle theta _h calculated in step S8, the calculated target turning angular speed V _t by using the following formula, the process proceeds to step S10.
V _t = (θ _h (t) −θ _h (t-1)) / dt

In step S10, the steering reaction force Fa corresponding to the actuator response is calculated from the following equation, and the process proceeds to step S11.
Fa = αg * (θ _h −θ _t )

In step S11, a driving current is output to the front wheel steering actuator 10 such that the actual current value of the steering actuator 10 matches the command current I _s (t) calculated in step S7, and the process proceeds to step S12.

In step S12, the actual turning angle θ _p of the front wheels 16, 16 is detected from the signal of the steering angle sensor 11, and the process proceeds to step S13.

In step S13, the actual turning angular velocity V _p is calculated from the actual turning angle θ _p calculated in step S12 using the following formula, and the process proceeds to step S14.
V _p = (θ _p (t) −θ _p (t-1)) / dt

In step S14, the steering reaction force Fb for the load input is calculated using the following equation, and the process proceeds to step S15.
Fb = α′g * (θ _p −θ _t )

  In step S15, the steering reaction force Fs for the steering input calculated in step S6, the steering reaction force Fa for the actuator response calculated in step S11, and the reaction force Fb for the load input calculated in step S14 are added. Then, the target steering reaction force F is calculated, and the process proceeds to step S15.

In step S16, the command current I _r (t) of the steering reaction force actuator 5 is calculated from the target steering reaction force F calculated in step S15 based on the following equation, and the process proceeds to step S17.

In step S17, a drive current is output to the steering reaction force actuator 5 so that the actual current value of the steering reaction force actuator 5 matches the command current I _r (t) calculated in step S16, and this control is terminated.

[Technical background]
In Japanese Patent Laid-Open No. 10-324261, a gear ratio (overall steering gear ratio) that is a ratio of a steering angle of a steering wheel to a steering angle of a front wheel is varied, and a target turning angle set based on the gear ratio is set. A technique for turning the front wheels accordingly is disclosed. In this prior art, when the absolute value of the turning angular velocity is large, the difference between the target turning angle and the actual turning angle and the difference between the target turning angular velocity and the actual turning angular velocity are given to the steering reaction force. Thus, the operation of the steering actuator is made to correspond to the operation of the steering wheel.

(Problem 1)
Since the steering reaction force is applied in a state where the delay of the normal steering actuator and the delay due to the input load to the steering actuator are mixed, the steering reaction force is applied more than necessary or the steering reaction force corresponding to the input load is There was a problem of not being given. For example, as shown in FIG. 9A, when the deviation increases, when the input load increases, the steering reaction force corresponding to the input load is not applied (FIG. 9B). Further, when the input load is reduced as shown in FIG. 10A, a steering reaction force is applied more than necessary (FIG. 10B).

That is, if the input load increases while the deviation θ _diff is increasing, it is necessary to lower the reaction force against the deviation halfway. On the other hand, if the input load is reduced while the deviation θ _diff is increasing, it is necessary to lower the gain with respect to the deviation halfway.

Further, when the reaction force is set in accordance with the deviation θ _diff , the load is input at random. Therefore, both the ideal characteristic shown in FIG. 9B and the ideal characteristic shown in FIG. Since the points must also be set arbitrarily, in the conventional control using the steering reaction force map based on the deviation, the steering reaction force becomes too heavy or conversely too light.

(Problem 2)
Since the steering reaction force is applied by the absolute value of the difference between the target turning angular velocity and the actual turning angular velocity, even when the phase of the turning actuator advances, the change cannot be given to the steering reaction force. (Same problem as lighter load).

[Steering reaction force control action according to input load]
In contrast, in the vehicle steering control device of the first embodiment, the estimated turning angle θ _{t with} respect to the target turning angle θ _h is based on the response of the front wheel turning actuator 10 by the front wheel turning angle estimation model G (s). the calculated (step S8), and thereby added to the steering reaction force Fs of the steering input frequency to the difference as steering reaction force Fa of the actuator response component, adding the difference between the actual turning angle theta _p for the estimated turning angle theta _t The input steering reaction force Fb is added to the steering input reaction force Fs (step S15).

  That is, by applying a reaction force Fa due to a normal response and a steering reaction force Fb corresponding to a position shift or response of the front wheel steering actuator 10 other than the normal to the steering reaction force Fs corresponding to the steering input, Responsivity due to vehicle loading conditions, which are load factors of the rudder actuator 10, vehicle load changes due to vehicle posture and running conditions, road surface changes such as curb catching and road surface μ, and deterioration of the front wheel steering actuator 10 A steering reaction force corresponding to the decrease or the like can be applied. In other words, by setting the reaction force gain that is appropriate for the input of the load / disturbance on top of the gain in the optimized normal response, the steering reaction force corresponding to the original steered state is set statically and It can also be realized dynamically.

Next, the effect will be described.
In the vehicle steering control device according to the first embodiment, the following effects can be obtained.

(1) A target turning angle θ _h corresponding to the steering state (steering angle θ _H ) of the front wheel steering actuator 10 that steers the front wheels 16 and 16 and the handle 6 operated by the driver is set. and the front wheel steering control unit 19a for driving and controlling the front wheel turning actuator 10 to match the steering angle theta _h, the steering reaction force actuator 5 that applies a steering reaction force to the steering wheel 6, the steering state of front wheels 16, 16 For a vehicle having a steering reaction force control unit 19b that sets a target steering reaction force F according to (actual turning angle θ _p ) and drives and controls the steering reaction force actuator 5 based on the target steering reaction force F In the steering control device, a front wheel turning angle estimation model block 107 that estimates the turning angle of the front wheels 16 and 16 based on the target turning angle θ _h and the response characteristics of the front wheel turning actuator 10, and the front wheels 16 and 16. a steering angle sensor for detecting the actual turning angle theta _p of Comprising 1, as the estimated turning angle theta _t is large deviation between the actual turning angle theta] p, the steering reaction force correction means for correcting the target steering reaction force F increases (gain block 112), the. Therefore, the steady input load to the front wheel steering actuator 10 can be reflected in the steering reaction force, and the application of the steering reaction force corresponding to the original steering state can be realized.

(2) the steering reaction force correction means (gain block 109, adder block 110), the more difference between the target steered angle theta _h and the estimated turning angle theta _t is large, the increase correcting the target steering reaction force F, The delay characteristic of the front wheel steering actuator 10 can be reflected in the steering reaction force.

  The second embodiment is an example in which the steering reaction force is corrected according to the deviation between the target turning angular speed and the estimated turning angular speed and the deviation between the estimated turning angular speed and the actual turning angular speed.

First, the configuration will be described.
FIG. 11 is an overall system diagram illustrating the vehicle steering control device according to the second embodiment. In the second embodiment, the vehicle behavior state quantity detecting unit for detecting the vehicle behavior state quantity is compared with the configuration of the first embodiment. The difference is in that a yaw rate sensor 21 that detects the yaw rate, a lateral G sensor 22 that detects the lateral acceleration of the vehicle, and a longitudinal G sensor 23 that detects the longitudinal acceleration of the vehicle are added.

  The control controllers 19 and 19 include a steering angle sensor 1, an encoder 2, torque sensors 3 and 3, a Hall IC, a steering unit encoder 10, a steering angle sensor 11, and a torque sensor (for road surface reaction force detection means). Equivalent) 12, 12, detection values from Hall IC, vehicle speed sensor 20, yaw rate sensor 21, lateral G sensor 22, front and rear G sensor 23 are input.

Next, the operation will be described.
[Front wheel steering and steering reaction force control method]
The front wheel steering control and steering reaction force control method of the second embodiment will be described with reference to the control block diagram of FIG. Only parts different from the first embodiment will be described.

In Example 2, the target steering angular velocity V _h that the target turning angle theta _h obtained by differentiating (differentiating block 104), differentiates the estimated turning angle theta _t (differential block 115; turning angular velocity estimation means) the estimated turning a deviation between the angular velocity V _t (subtraction block 121), with respect to the deviation, with force gain βp having the characteristics shown in FIG. 13, obtains the steering reaction force actuator response component based on the steering angular velocity deviation (gain Block 122). This steering reaction force and the steering reaction force αg * (θ _h −θ _t ) corresponding to the actuator response based on the turning angle deviation are added (addition block 123) to obtain the steering reaction force Fa corresponding to the actuator response. In a subtraction block 121 and gain block 122, as the deviation between the target turning angular velocity V _h and the estimated turning angular velocity V _t is large, a steering reaction force Fa of the actuator response component is increased, the target steering reaction force F largely corrected Steering reaction force correcting means is configured.
Fa = αg * (θ _h −θ _t ) + βp * (V _h −V _t )
Here, the reaction force gain βp is set by the magnitude of the steering reaction force for transmitting the front wheel turning actuator response delay to the driver. By the gain block 122 and summation block 123, as the deviation between the target turning angular velocity V _h and the estimated turning angular velocity V _t is large, a steering reaction force Fa of the actuator response component is increased, the target steering reaction force F largely corrected Steering reaction force correcting means is configured.

FIG. 14 shows a steering reaction force characteristic obtained by adding a transient component of the steering reaction force Fa corresponding to the actuator response to the steering reaction force K _d * dθ _h / dt corresponding to the transient steering input. Thereby, as shown in FIG. 14, a steering reaction force corresponding to a transient response delay of the front wheel steering actuator can be applied to the handle 6. In FIG. 14, a steering reaction force is applied to a region where the target turning angular velocity V _h is low and a region where the target turning angular velocity V _h is high. This is because the low-frequency and high-frequency responsiveness of the front wheel turning actuator is poor. In this case, the amount of reaction force added to the target turning angular velocity V _h varies depending on the response characteristics of the actuator.

In the second embodiment, the estimated turning angular velocity V _{t obtained} by differentiating the estimated turning angle θ _t (derivative block 115; turning angular velocity estimating means) and the actual turning angle θ _p are differentiated (derivative block 116; actual turning). The reaction force gain β′p having the characteristics shown in FIG. 15 is used for the deviation (addition / subtraction block 117) from the actual turning angular velocity V _p (steering angular velocity detection means), and the transient load fluctuation received by the front wheel steering actuator The steering reaction force corresponding to is calculated (gain block 118). Here, the reaction force gain β′p is set to increase in proportion to the deviation between the estimated turning angular velocity V _t and the actual turning angular velocity V _p .
Fb = α′g * (θ _h −θ _t ) + β′p (V _h −V _t )

By adding the steering reaction force Fb corresponding to the load input to Fs + Fa (addition block 114), as shown in FIG. 16, it is possible to reflect the transient change in load of the front wheel steering actuator in the steering reaction force. it can. Note that, at low-frequency and high-frequency turning angular velocities, the response of the front wheel turning actuator 10 is poor, so the response to transient load fluctuations is also poor and the steering reaction force is large. Gain block 118, the addition block 114, as the deviation between the estimated turning angular velocity V _t and the actual turning angular velocity V _p is large, by increasing the steering reaction force Fb of the load input frequency, the correction amount of the target steering reaction force F Steering reaction force correcting means for correcting to increase is configured.

In the second embodiment, the reaction force gains α′g and β′p for determining the steering reaction force Fb corresponding to the load input are changed according to the vehicle behavior and the road surface input.
The reaction force gain α′g is changed by the yaw rate Y, the lateral acceleration L, the longitudinal acceleration D, and the road surface reaction force f (gain setting block 123).
α′g = α0Y + α1L + α2D + α3f

The reaction force gain β′p includes the yaw angular acceleration Y ′ obtained by differentiating the yaw rate Y (differentiating block 125), the lateral jerk L ′ obtained by differentiating the lateral acceleration L (derivative block 126), and the longitudinal acceleration D differentiated (derivative block 127). The front / rear jerk D ′ and the road surface reaction force f are changed according to a road surface reaction force change amount f ′ obtained by differentiating (differential block 127) (gain setting block 124).
β′p = β0Y ′ + β1L ′ + β2D ′ + β3f ′

  Α0, α1, α2, β0, β1, and β2 are gains according to the input load. By appropriately setting these according to the input characteristics of each factor and vehicle sensitivity, each of the input loads of the steering reaction force By changing the weight, the vehicle behavior can be transmitted to the driver as a steering reaction force.

[Front wheel steering and steering reaction force control processing]
FIG. 17 is a flowchart illustrating a flow of front wheel steering and steering reaction force control processing executed by the controller 19 of the second embodiment. In addition, the same step number is provided to the step which performs the same process as Example 1, and only a different step is demonstrated.

  In step S21, the yaw rate Y, the lateral acceleration L, and the longitudinal acceleration D are detected from the signals of the yaw rate sensor 21, the lateral G sensor 22, and the longitudinal G sensor 23 as vehicle behavior state quantities, and the road surface is derived from the signals of the torque sensors 12, 12. The reaction force f is detected, and the process proceeds to step S22.

  In step S22, the differential values Y ′, L ′, D ′, and f ′ of yaw rate Y, lateral acceleration L, longitudinal acceleration D, and road reaction force f detected in step S21 are calculated, and the process proceeds to step S23.

In step S23, a reaction force gain α′g is calculated from the yaw rate Y, lateral acceleration L, longitudinal acceleration D, and road reaction force f detected in step S21 using the following formula, and the process proceeds to step S24.
α′g = α0Y + α1L + α2D + α3f

In step S24, the reaction force gain β is calculated from the yaw rate Y, lateral acceleration L, longitudinal acceleration D, and differential values Y ′, L ′, D ′, f ′ of the road surface reaction force f calculated in step S22 using the following equations. 'p is calculated, and the process proceeds to step S25.
β′p = β0Y ′ + β1L ′ + β2D ′ + β3f ′

In step S25, the steering reaction force Fb corresponding to the load input is calculated from the reaction force gain α′g calculated in step S23 and the reaction force gain β′p calculated in step S24 using the following equation. Move to S15.
Fb = α′g * (θ _p −θ _t ) + β′p (V _p −V _t )

[Steering reaction force control action according to load input factor]
In the second embodiment, the load input is divided for each factor, and the vehicle yaw rate Y, the lateral G, the front and rear G, which are the substitute characteristics of the vehicle behavior state, and the road surface reaction force, which is the substitute characteristic of the road surface condition and the load state of the front wheels 16,16. Since the steering reaction force Fb corresponding to the load input is varied according to the input characteristics such as the above and the vehicle sensitivity (steps S23 and S24), the steering reaction force corresponding to each input load can be transmitted to the driver.

Next, the effect will be described.
In the vehicle steering control apparatus according to the second embodiment, the following effects can be obtained in addition to the effects (1) and (2) of the first embodiment.

(3) A differential block 115 for calculating the estimated turning angular velocity V _t and a differential block 116 for detecting the actual turning angular velocity V _p , and the steering reaction force correcting means (gain block 118, addition block 114), As the deviation between the estimated turning angular velocity V _t and the actual turning angular velocity V _p is larger, the correction amount of the target steering reaction force F is increased. Therefore, the load fluctuation which changes transiently of the front wheel steering actuator 10 can be reflected in the steering reaction force.

  (4) A yaw rate sensor 21, a lateral G sensor 22, and a longitudinal G sensor 23 for detecting the yaw rate Y, the lateral acceleration L, and the longitudinal acceleration D of the vehicle, and the steering reaction force correcting means (gain block 112, gain block 113) are As the yaw rate Y, lateral acceleration L, and longitudinal acceleration D increase, the steering reaction force Fb corresponding to the load input is increased. Therefore, it is possible to generate a steering reaction force corresponding to the load fluctuation due to the vehicle behavior change and to apply the steering reaction force corresponding to the vehicle behavior.

  (5) The torque sensors 12 and 12 that detect the road surface reaction force f input to the front wheels 16 and 16 are provided, and the steering reaction force correction means (gain block 112 and gain block 113) increases as the road surface reaction force f increases. The steering reaction force Fb for the load input is increased. Therefore, the steering reaction force according to the road surface reaction force f can be transmitted to the driver.

(6) comprises a differential block 115 calculates the estimated turning angular velocity V _t, the derivative block 104 sets the target steering angular velocity V _h according to the target turning angle theta _h, the steering reaction force correction means (subtraction block 121, a gain block 122), as the deviation between the target turning angular velocity V _h and the estimated turning angular velocity V _t is large, increased corrects the target steering reaction force F. Therefore, the transient input load of the front wheel steering actuator 10 can be reflected in the steering reaction force, and the application of the steering reaction force corresponding to the original steering state can be realized.

(Other examples)
The best mode for carrying out the present invention has been described based on the first and second embodiments. However, the specific configuration of the present invention is not limited to the first and second embodiments. Design changes and the like within the scope not departing from the gist are also included in the present invention.

  For example, in the first and second embodiments, the steer-by-wire system in which the steering wheel and the tire are mechanically separated has been described. However, the present invention includes a steering angle ratio variable control mechanism and a power steering control mechanism. It can also be applied to vehicles. In this case, the steering reaction force applied to the driver can be changed by changing the power assist force by the power steering control mechanism according to the response delay of the turning angle control by the steering angle ratio variable control.

  In the first and second embodiments, the steering control unit (front wheel steering control unit 19a) and the steering reaction force control unit (steering reaction force control unit 19b) are separately provided in the control controller 19. It may be integrated.

1 is an overall system diagram illustrating a vehicle steering control apparatus according to a first embodiment. 3 is a system block diagram of a control controller 19. FIG. FIG. 3 is a control block diagram according to the first embodiment. It is a characteristic view of the reaction force gain αg with respect to the deviation between the target turning angle and the estimated turning angle. FIG. 6 is a steady characteristic diagram of a steering reaction force in which an actuator response component Fa is added to a steering input component Fs. It is a characteristic view of reaction force gain α′g with respect to the deviation between the estimated turning angle and the actual turning angle. FIG. 5 is a steady characteristic diagram of a steering reaction force in which an actuator response Fa and a load input Fb are added to a steering input Fs. 6 is a flowchart illustrating a flow of front wheel steering and steering reaction force control processing executed by the controller 19 of the first embodiment. It is a figure which shows the problem of a prior art. It is a figure which shows the problem of a prior art. It is a whole system figure which shows the steering control apparatus for vehicles of Example 2. FIG. FIG. 6 is a control block diagram of Embodiment 2. FIG. 6 is a characteristic diagram of a reaction force gain βg with respect to a deviation between a target turning angular velocity and an estimated turning angular velocity. FIG. 6 is a transient characteristic diagram of a steering reaction force in which an actuator response component Fa is added to a steering input component Fs. It is a characteristic view of the reaction force gain β′p with respect to the deviation between the estimated turning angular velocity and the actual turning angular velocity. FIG. 6 is a transient characteristic diagram of a steering reaction force in which an actuator response Fa and a load input Fb are added to a steering input Fs. It is a flowchart which shows the flow of the front wheel steering and steering reaction force control process which are performed by the control controller 19 of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering angle sensor 2 Encoder 3 Torque sensor 5 Steering reaction force actuator 6 Handle 7 Cable column 8a Column shaft 8b Pulley shaft 9 Clutch 10 Encoder 11 Steering angle sensor 12 Torque sensor 14 Front wheel steering actuator 15 Steering mechanism 16 Front wheel 17 Pinion shaft 19 Control controller 20 Vehicle speed sensor

Claims (7)

A steering actuator that steers steering wheels;
A steering control means for setting a target turning angle according to the steering state of the steering unit operated by the driver, and driving and controlling the steering actuator so as to coincide with the target turning angle;
A steering reaction force actuator for applying a steering reaction force to the steering unit;
A steering reaction force control means for setting a steering reaction force command value corresponding to the steered state of the steered wheels, and driving and controlling the steering reaction force actuator based on the steering reaction force command value;
In a vehicle steering control device having:
Based on the target turning angle and the response characteristic of the turning actuator, a turning angle estimation means for estimating the turning angle of the steered wheel;
An actual turning angle detection means for detecting an actual turning angle of the steering wheel;
Steering reaction force correcting means for correcting the steering reaction force command value to be larger as the deviation between the estimated turning angle and the actual turning angle is larger;
A vehicle steering control device comprising: The vehicle steering control device according to claim 1,
Steering angular velocity estimation means for estimating the steering angular velocity of the steered wheel;
An actual turning angular velocity detecting means for detecting an actual turning angular velocity of the steered wheel;
With
The vehicle steering control device, wherein the steering reaction force correction means increases the correction amount of the steering reaction force command value as the deviation between the estimated turning angular velocity and the actual turning angular velocity is larger. The vehicle steering control device according to claim 1 or 2,
Vehicle behavior state quantity detection means for detecting the behavior state quantity of the vehicle,
The steering control device for a vehicle, wherein the steering reaction force correction means increases the correction amount as the vehicle behavior state amount increases. The vehicle steering control device according to any one of claims 1 to 3,
Road surface reaction force detecting means for detecting the road surface reaction force input to the steering wheel,
The vehicle steering control device, wherein the steering reaction force correcting means increases the correction amount as the road surface reaction force increases. The vehicle steering control device according to any one of claims 1 to 4,
The steering control device for a vehicle according to claim 1, wherein the steering reaction force correction unit corrects the steering reaction force command value as the deviation between the target turning angle and the estimated turning angle increases. The vehicle steering control device according to any one of claims 1 to 5,
A steering angular velocity estimating means for estimating a steering angular velocity of the steered wheel;
The steering control means sets a target steering angular velocity according to a steering state of the steering unit,
The vehicle steering control device, wherein the steering reaction force correction unit corrects the steering reaction force command value to a greater extent as a deviation between the target turning angular velocity and the estimated turning angular velocity is larger. A steering actuator that steers steering wheels;
A steering control means for setting a target turning angle according to the steering state of the steering unit operated by the driver, and driving and controlling the steering actuator so as to coincide with the target turning angle;
A steering reaction force actuator for applying a steering reaction force to the steering unit;
A steering reaction force control means for setting a steering reaction force command value corresponding to the steered state of the steered wheels, and driving and controlling the steering reaction force actuator based on the steering reaction force command value;
In a vehicle steering control device having:
Based on the target turning angle and the response characteristics of the turning actuator, the turning angle of the steered wheels is estimated,
Detecting the actual steering angle of the steering wheel,
The vehicle steering control device, wherein the steering reaction force command value is corrected to be larger as the deviation between the estimated turning angle and the actual turning angle is larger.

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