JP4006573B2 - Vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a vehicle such as an automobile, and more particularly to a vehicle control device that controls a vehicle based on a lateral acceleration or a yaw rate of the vehicle.
[0002]
[Prior art]
As one of the control devices for vehicles such as automobiles, for example, as described in JP-A-4-283169, it has two vehicle speed sensors, and the rate of change of the output of each vehicle speed sensor is compared. Conventionally, a vehicle control device configured to control a vehicle based on a detection value of a vehicle speed sensor corresponding to a small output is known. According to this type of vehicle control device, it is possible to accurately detect the vehicle speed and accurately control the vehicle as compared with the case where the vehicle is controlled based on the detection value of one vehicle speed sensor.
[0003]
[Problems to be solved by the invention]
However, in the conventional vehicle control device as described in the above publication, only a redundant system in which the vehicle state quantity detected by the two sensors is the same can be dealt with, for example, the lateral acceleration and yaw rate of the vehicle. As described above, there is a problem that a redundant system of a combination of two sensors for detecting two types of vehicle state quantities that can estimate the other vehicle state quantity from one vehicle state quantity cannot be dealt with.
[0004]
Further, in the conventional vehicle control device as described in the above publication, the same vehicle state quantity must be detected by two similar sensors, and the rate of change of the output of each sensor must be compared. The vehicle state quantity is detected by each of the two sensors, and the vehicle state quantity to be used for vehicle control is not obtained unless the detected value is compared. Therefore, the detection is performed using the detected vehicle state quantity. There is a problem that a delay in vehicle control is unavoidable, and further, there is a problem that the calculation load of the control device is high because the rate of change between the two sensor outputs must be constantly compared.
[0005]
The present invention relates to a conventional vehicle control apparatus configured to select the vehicle state quantity to be used for vehicle control by detecting the same vehicle state quantity by a plurality of sensors and comparing the rate of change of their outputs. The main object of the present invention is to provide a vehicle control apparatus for controlling a vehicle based on a lateral acceleration or a yaw rate of the vehicle. When the vehicle is in a steady running state, the steering wheel Focusing on the high reliability of vehicle lateral acceleration and yaw rate obtained based on the steering angle of the vehicle, the relationship between the detected value of the lateral acceleration sensor and the reference value or the detected value of the yaw rate sensor and the reference value with these as reference values By selecting the detection value based on the relationship between the horizontal acceleration sensor and the yaw rate sensor, it is possible to accurately detect the redundant system of the combination of the lateral acceleration sensor and the yaw rate sensor while preventing a delay in control and an increase in calculation load. It is that makes it possible to control the vehicle based on the acceleration or yaw rate.
[0006]
[Means for Solving the Problems]
  According to the present invention, the main problem described above is that the vehicle control device controls the vehicle based on at least the lateral acceleration of the vehicle, the vehicle speed detection means, the steering angle detection means for detecting the steering angle of the steering wheel, and the vehicle A lateral acceleration sensor for detecting the lateral acceleration of the vehicle and a yaw rate sensor for detecting the yaw rate of the vehicle, and based on the vehicle speed detected by the vehicle speed detecting means and the steering angle detected by the steering angle detecting means. Means for calculating acceleration;The vehicle speed detected by the vehicle speed detection means andMeans for calculating an estimated lateral acceleration of the vehicle based on the yaw rate detected by the yaw rate sensor; and a first of the reference lateral acceleration and the lateral acceleration detected by the lateral acceleration sensor when the vehicle is in a steady running state. Comparing means for comparing a deviation and a second deviation between the reference lateral acceleration and the estimated lateral acceleration, and the smaller deviation of the first and second deviations based on the comparison result of the comparing means Selecting means for selecting a corresponding detection value of the lateral acceleration sensor or the yaw rate sensor, and controlling the vehicle based on the lateral acceleration of the vehicle based on the detection value selected by the selection means. A control device (configuration of claim 1) or a vehicle control device that controls a vehicle based on at least the yaw rate of the vehicle, and detects the vehicle speed detection means and the steering angle of the steered wheels. A steering angle detecting means, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, and a yaw rate sensor for detecting the yaw rate of the vehicle, the vehicle speed detected by the vehicle speed detecting means and detected by the steering angle detecting means Means for calculating a reference yaw rate of the vehicle based on the rudder angle;The vehicle speed detected by the vehicle speed detection means andMeans for calculating an estimated yaw rate of the vehicle based on the lateral acceleration detected by the lateral acceleration sensor, a first deviation between the reference yaw rate and the yaw rate detected by the yaw rate sensor when the vehicle is in a steady running state, and Comparing means for comparing a second deviation between the reference yaw rate and the estimated yaw rate, and the horizontal corresponding to the smaller deviation of the first and second deviations based on the comparison result of the comparing means. A vehicle control device for controlling the vehicle based on a yaw rate of the vehicle based on the detection value selected by the selection unit. 2).
[0007]
  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 1 or 2, the comparison means is a vehicle based on the steering angle detected by the steering angle detection means. The vehicle is in a straight running condition.DeterminedSometimes configured to compare the first and second deviations.
[0008]
[Action and effect of the invention]
  In general, when a vehicle is in a steady running state,Vehicle speed andThe lateral acceleration and yaw rate of the vehicle can be estimated with high accuracy based on the steering angle of the steered wheels, and the steering angle detecting means such as the vehicle speed detecting means and the steering angle sensor for detecting the steered angle of the steered wheels is a lateral acceleration sensor or Compared to a yaw rate sensor, it is less susceptible to detection errors due to temperature changes and so on, so-called zero point deviation is less likely to occur.Vehicle speed andThe lateral acceleration and yaw rate of the vehicle estimated based on the steering angle of the steered wheels accurately represent the actual lateral acceleration and yaw rate of the vehicle, respectively.
[0009]
  So when the vehicle is in steady stateVehicle speed andIf the lateral acceleration or yaw rate of the vehicle estimated based on the steering angle of the steered wheels is used as a reference value, and the magnitude of deviation between the detected value of the lateral acceleration sensor or yaw rate sensor and the reference value is compared, the magnitude of the deviation is small. It can be determined that the sensor corresponding to the direction accurately detects the actual lateral acceleration or yaw rate of the vehicle.
[0010]
  According to claim 1, the reference lateral acceleration of the vehicle is calculated based on the vehicle speed and the steering angle of the steered wheels,Vehicle speed andThe estimated lateral acceleration of the vehicle is calculated based on the yaw rate detected by the yaw rate sensor, and the first deviation between the reference lateral acceleration and the lateral acceleration detected by the lateral acceleration sensor when the vehicle is in a steady running state and the reference lateral acceleration. And the estimated lateral acceleration are compared, and the detected value of the lateral acceleration sensor or yaw rate sensor corresponding to the smaller deviation of the first and second deviations is selected based on the comparison result. Since the vehicle is controlled based on the lateral acceleration of the vehicle based on the selected detection value, the selected detection value accurately represents the actual lateral acceleration or yaw rate of the vehicle compared to the other detection value. Therefore, the vehicle can be controlled more accurately based on the lateral acceleration of the vehicle than when the vehicle is controlled based only on the detection value of the lateral acceleration sensor.
[0011]
  Further, according to the configuration of claim 2, the reference yaw rate of the vehicle is calculated based on the vehicle speed and the steering angle of the steered wheels,Vehicle speed andAn estimated yaw rate of the vehicle is calculated based on the lateral acceleration detected by the lateral acceleration sensor, and the first deviation between the reference yaw rate and the yaw rate detected by the yaw rate sensor when the vehicle is in a steady running state, and the reference yaw rate and the estimated yaw rate And the detection value of the lateral acceleration sensor or the yaw rate sensor corresponding to the smaller deviation of the first and second deviations is selected based on the comparison result. Since the vehicle is controlled based on the vehicle yaw rate based on the detected value, the selected detected value accurately represents the actual lateral acceleration or yaw rate of the vehicle relative to the other detected value, and therefore the yaw rate sensor The vehicle can be controlled based on the yaw rate of the vehicle more accurately than when the vehicle is controlled based only on the detected value.
[0012]
  According to the first and second aspects, the lateral acceleration and yaw rate of the vehicle are detected by the lateral acceleration sensor and the yaw rate sensor, respectively, and the vehicle state quantity detected by one of the sensors when the vehicle is in a steady running state.And vehicle speedThe vehicle state quantity on the other side is estimated based on the above, so that the lateral acceleration or yaw rate of the vehicle can be accurately detected for the redundant system of the lateral acceleration sensor and the yaw rate sensor, and the comparison between the first and second deviations It is not necessary to constantly compare the vehicle state quantity detected by the same type of sensor as in the conventional vehicle control device described in the above-mentioned publication. The calculation load of the apparatus can be reduced.
[0013]
  As described above, the steering angle detection means such as the steering angle sensor for detecting the steering angle of the steered wheel is less susceptible to detection errors due to temperature changes and the like than the lateral acceleration sensor and yaw rate sensor, and so-called zero point deviation is less likely to occur. If the straight traveling state of the vehicle is determined based on the rudder angle detected by the rudder angle detecting means, the straight traveling state of the vehicle can be detected more accurately than when based on the detection values of the lateral acceleration sensor and the yaw rate sensor. it can. When the vehicle is running straight, the vehicle's reference lateral acceleration and reference yaw rate calculated based on the vehicle speed and the steering angle of the steered wheels areBothTherefore, the reference lateral acceleration and the reference yaw rate can be calculated more accurately than when the vehicle is in a steady turning state, and the first and second deviations can be compared accurately. .
[0014]
  According to the configuration of the third aspect, the straight traveling state of the vehicle is determined based on the rudder angle detected by the rudder angle detecting means, and the vehicle is in the straight traveling state.DeterminedSince the first and second deviations are sometimes compared, the first and second deviations are determined when the straight running state of the vehicle is determined based on the detection values of the lateral acceleration sensor and the yaw rate sensor or when the vehicle is in a steady turning state. The first and second deviations can be compared more accurately than when the second deviation is compared.
[0015]
[Preferred embodiment of the problem solving means]
According to one preferred aspect of the present invention, in the configuration of claim 1, the comparison means includes the average value of the first deviation and the second value at a predetermined time when the vehicle is in a steady running state. Calculates the average value of the deviations and compares the average values of the first and second deviations, and the selection means corresponds to the average value of the smaller one of the average values of the first and second deviations. The detection value of the lateral acceleration sensor or the yaw rate sensor is selected (preferred aspect 1).
[0016]
According to another preferred aspect of the present invention, in the configuration of claim 1, the means for calculating the estimated lateral acceleration of the vehicle includes the yaw rate detected by the yaw rate sensor and the vehicle speed detected by the vehicle speed detecting means. The estimated lateral acceleration of the vehicle is calculated as a product of (preferred aspect 2).
[0017]
According to another preferred aspect of the present invention, in the configuration of claim 1, the vehicle control device is configured to multiply the product of the detection value of the yaw rate sensor and the vehicle speed when the detection value of the yaw rate sensor is selected by the selection means. And calculating the lateral acceleration of the vehicle and controlling the vehicle based on the lateral acceleration (preferred aspect 3).
[0018]
According to another preferred aspect of the present invention, in the configuration of claim 1, the comparison means is a rate of change of the lateral acceleration detected by the lateral acceleration sensor, a rate of change of the yaw rate detected by the yaw rate sensor, or The vehicle is configured to determine that the vehicle is in a steady running state when the rate of change of the reference lateral acceleration of the vehicle or the rate of change of the estimated lateral acceleration of the vehicle is substantially constant for a predetermined time or longer ( Preferred embodiment 4).
[0019]
According to another preferred embodiment of the present invention, in the configuration of claim 1, the comparison means includes a rate of change of the lateral acceleration detected by the lateral acceleration sensor, a rate of change of the yaw rate detected by the yaw rate sensor, It is configured to determine that the vehicle is in a steady running state when at least two of the change rate of the reference lateral acceleration of the vehicle and the change rate of the estimated lateral acceleration of the vehicle are substantially constant for a predetermined time or more. (Preferred embodiment 5).
[0020]
According to another preferred aspect of the present invention, in the configuration of claim 2, the comparison means includes the average value of the first deviation and the first value at a predetermined time when the vehicle is in a steady running state. The average value of the two deviations is calculated and the average value of the first and second deviations is compared, and the selection means selects the average value of the smaller deviations of the average values of the first and second deviations. The detection value of the lateral acceleration sensor or yaw rate sensor corresponding to is selected (preferred aspect 6).
[0021]
According to another preferred aspect of the present invention, in the configuration of claim 2, the means for calculating the estimated yaw rate of the vehicle has the vehicle speed detected by the vehicle speed detecting means detected by the vehicle speed detecting means. The estimated yaw rate of the vehicle is calculated as a value divided by (preferred aspect 7).
[0022]
According to another preferred aspect of the present invention, in the configuration of claim 2, the vehicle control device sets the detection value of the lateral acceleration sensor to the vehicle speed when the detection value of the lateral acceleration sensor is selected by the selection means. The yaw rate of the vehicle is calculated as a value divided by the above, and the vehicle is controlled based on the yaw rate (preferred aspect 8).
[0023]
According to another preferred aspect of the present invention, in the configuration of claim 2, the comparing means is a rate of change of the lateral acceleration detected by the lateral acceleration sensor or a rate of change of the yaw rate detected by the yaw rate sensor, or The vehicle is configured to determine that the vehicle is in a steady running state when the rate of change of the reference yaw rate of the vehicle or the rate of change of the estimated yaw rate of the vehicle is substantially constant for a predetermined time or longer (preferred mode) 9).
[0024]
According to another preferred aspect of the present invention, in the configuration of claim 2, the comparison means includes a rate of change of the lateral acceleration detected by the lateral acceleration sensor, a rate of change of the yaw rate detected by the yaw rate sensor, It is configured to determine that the vehicle is in a steady running state when at least two of a change rate of the reference yaw rate of the vehicle and a change rate of the estimated yaw rate of the vehicle are substantially constant for a predetermined time or longer. (Preferred embodiment 10).
[0025]
  According to another preferred embodiment of the invention, the above claims1In the composition of,ratioThe comparing means determines that the vehicle is in a straight traveling state when the vehicle's reference lateral acceleration is substantially zero for a predetermined time or longer.The first and second deviations are compared when it is determined that the vehicle is running straight.(Preferred aspect 11).
[0026]
  According to another preferred embodiment of the invention, the above claims2In the composition of,ratioThe comparing means determines that the vehicle is in a straight traveling state when the vehicle's reference yaw rate is substantially zero for more than a predetermined time.The first and second deviations are compared when it is determined that the vehicle is running straight.(Preferred aspect 12).
[0027]
According to another preferred aspect of the present invention, in the configuration of claim 3, the state in which the rudder angle detected by the rudder angle detecting means is substantially zero continues for a predetermined time or more. The vehicle is configured to determine that the vehicle is in a straight traveling state (preferred aspect 13).
[0028]
According to another preferred aspect of the present invention, in the configuration of claim 1, the vehicle control device is a braking force distribution control device for controlling the braking force distribution of the front and rear wheels during turning braking of the vehicle. And braking force control means for controlling the braking force of the rear wheels. The braking force control means increases the magnitude of the product of the vehicle lateral acceleration and the vehicle speed based on the detection value selected by the selection means. The braking force of the front wheel or the rear wheel is controlled to increase the distribution ratio of the braking force of the front wheel (preferred aspect 14).
[0029]
According to another preferred aspect of the present invention, in the configuration of claim 2, the vehicle control device is a rear wheel steering control device for controlling the steering angle of the rear wheel, and is selected by the reference yaw rate and the selection means. The steering angle of the rear wheels is controlled so that the deviation from the yaw rate of the vehicle based on the detected value is reduced (preferred aspect 15).
[0030]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.
[0031]
First embodiment
FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle control device according to the present invention configured to perform front and rear wheel distribution control of braking force during turning braking based on the lateral acceleration of the vehicle.
[0032]
In FIG. 1, 10FL and 10FR indicate the left and right front wheels of the vehicle 12, respectively, and 10RL and 10RR indicate the left and right rear wheels, respectively. The left and right front wheels 10FL and 10FR, which are steered wheels, are steered via tie rods 18L and 18R by a rack and pinion type power steering device 16 that is driven in response to turning of the steering wheel 14 by the driver.
[0033]
The braking force of each wheel is controlled by controlling the braking pressure of the wheel cylinders 24FR, 24FL, 24RR, 24RL by the hydraulic circuit 22 of the braking device 20. Although not shown in the drawing, the hydraulic circuit 22 includes an oil reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven according to the depression operation of the brake pedal 26 by the driver. It is controlled by the master cylinder 28 and, if necessary, is controlled by the electric controller 30 as will be described in detail later.
[0034]
A steering column to which the steering wheel 14 is connected is provided with a steering angle sensor 32 that detects the steering angle θ. The vehicle 12 includes a vehicle speed sensor 34 for detecting the vehicle speed V, a lateral acceleration sensor 36 for detecting the vehicle lateral acceleration Gy, a yaw rate sensor 38 for detecting the yaw rate Yr of the vehicle, and the pressure in the master cylinder 28 as the master cylinder pressure Pm. As shown in FIG. The steering angle sensor 32, the lateral acceleration sensor 36, and the yaw rate sensor 38 detect the steering angle, the yaw rate, and the lateral acceleration, respectively, with the left turning direction of the vehicle being positive.
[0035]
As shown in the figure, a signal indicating the steering angle θ detected by the steering angle sensor 32, a signal indicating the vehicle speed V detected by the vehicle speed sensor 34, a signal indicating the lateral acceleration Gy detected by the lateral acceleration sensor 36, and a yaw rate sensor 38 A signal indicating the yaw rate Yr detected by the above is input to the electronic control unit 30.
[0036]
Although not shown in detail in the figure, the electronic control device 30 has, for example, a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other via a bidirectional common bus. Includes a microcomputer.
[0037]
The electronic control unit 30 follows the flowchart shown in FIG. 2 as will be described later, and the target braking pressure Pti (i = fl, fr) for the left and right front wheels and the left and right rear wheels according to the braking operation amount (master cylinder pressure Pm) of the driver. , Rl, rr), the braking pressure Pi of each wheel (i = fl, fr, rl, rr) is controlled to the corresponding target braking pressure Pti, and braking is performed when the braking slip of the wheel is excessive. A target braking pressure Pti for reducing the slip is calculated, thereby performing anti-skid control.
[0038]
In the illustrated embodiment, when the vehicle is in a turning braking state, the electronic control unit 30 increases the braking pressure of the front wheels as the product Gy × V of the lateral acceleration Gy of the vehicle and the vehicle speed V increases. When the product Gy × V is very large, the braking pressure on the rear rear wheel is fully reduced, so that if the driver performs a braking operation while turning the vehicle, By controlling the power front / rear wheel distribution ratio closer to the front wheels, the front / rear wheel distribution control of the braking force during turning braking is performed to prevent the yaw rate of the vehicle from increasing.
[0039]
Further, the electronic control unit 30 calculates a reference lateral acceleration Gyb of the vehicle based on the steering angle θ and the vehicle speed V according to the flowchart shown in FIG. 3 as described later, and estimates the estimated lateral of the vehicle based on the yaw rate γ and the vehicle speed V of the vehicle. The acceleration Gyh is calculated, and the magnitude of the deviation between the reference lateral acceleration Gyb and the detected vehicle lateral acceleration Gy when the vehicle is in a steady running state, and the magnitude of the deviation between the reference lateral acceleration Gyb and the estimated lateral acceleration Gyh. The flag Fs is set so that the lateral acceleration Gy or estimated lateral acceleration Gyh having the smaller deviation, that is, the higher reliability is used as the lateral acceleration of the vehicle in the front and rear wheel distribution control of the braking force. Set to 1 or 2.
[0040]
Next, prior to the description of the flowcharts shown in FIGS. 2 and 3, the principle of the front and rear wheel distribution control of the braking force in the first embodiment will be described.
[0041]
According to the vehicle model, if the stability factor is Kh, the vehicle speed is V, the steering angle is θ, the steering gear ratio is N, and the vehicle wheelbase is L, the vehicle yaw rate Yr is given by expressed.
Yr = {1 / (1 + Kh × V²)} × (θ × V) / (N × L) (1)
[0042]
(1 + Kh × V on both sides of Equation 1 above)²), The following formula 2 is obtained. When the lateral acceleration of the vehicle is Gy, the following formula 3 is obtained from the relationship of Gy = Yr × V.
Yr + Kh × (Yr × V) × V = (θ × V) / (N × L) (2)
Yr = (θ × V) / (N × 1) −Kh × Gy × V (3)
[0043]
In general, in an actual vehicle, when the vehicle is braked during steady turning, a phenomenon in which the vehicle tries to enter the inside of the turn despite a constant steering angle, that is, an undesired phenomenon in which the yaw rate Yr becomes large occurs. .
[0044]
When this phenomenon is applied to Equation 3 above, assuming that the yaw rate before braking is Yr1, the yaw rate after braking is Yr2, and changes in vehicle speed and lateral acceleration before and after braking are small, these yaw rates are as follows: Since it is expressed by the following equations 4 and 5,
Yr1 = (θ × V) / (N × 1) −Kh1 × Gy × V (4)
Yr2 = (θ × V) / (N × 1) −Kh2 × Gy × V (5)
The increase in the yaw rate Yr in the above phenomenon is Yr2> Yr1, and in order to suppress the increase in the yaw rate Yr, the change amount of the yaw rate represented by the following equation 6 should be reduced. .
Yr2−Yr1 = (Kh1−Kh2) × Gy × V (6)
[0045]
It has been confirmed in actual vehicles that the stability factor Kh tends to increase as the front-rear wheel distribution ratio of the braking force becomes closer to the front wheels. Therefore, in order to suppress the increase in the yaw rate Yr after braking when the vehicle is turning, the larger the product Gy × V of the lateral acceleration Gy and the vehicle speed V, the more the change in stability factor (Kh1−Kh2 ) Is reduced, that is, the front-rear wheel distribution ratio of the braking force may be controlled closer to the front wheels.
[0046]
Therefore, in the front and rear wheel distribution control of the braking force in the illustrated first embodiment, the lateral acceleration Gy or the estimated lateral acceleration Gyh with higher reliability, that is, the lateral acceleration that accurately represents the actual lateral acceleration of the vehicle. The acceleration is selected as the lateral acceleration Gy of the vehicle in the front-rear wheel distribution control, and the front-rear wheel distribution ratio of the braking force is controlled closer to the front wheel as the product Gy × V of the lateral acceleration Gy of the vehicle and the vehicle speed V increases. Thus, the running stability of the vehicle at the time of turning braking of the vehicle is improved with high accuracy.
[0047]
Next, the front and rear wheel distribution control routine for the braking force in the illustrated first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.
[0048]
First, in step 10, a signal indicating the steering angle θ is read, and in step 20, the target braking pressure Pti of each wheel is calculated based on the master cylinder pressure Pm, and anti-skid control is required. In some cases, a target braking pressure Pti required to reduce excessive braking slip of the wheel is calculated in a manner known in the art.
[0049]
In step 30, it is determined whether or not a flag Fs set as described later is 1 according to the routine shown in FIG. 3, and when an affirmative determination is made, in step 32, step 40 and subsequent steps. When the lateral acceleration Gy of the vehicle to be used for the above control is set to the lateral acceleration Gy detected by the lateral acceleration sensor 36, and a negative determination is made, the routine proceeds to step 34.
[0050]
In step 34, it is determined whether or not the flag Fs is 2. If an affirmative determination is made, in step 36, the lateral acceleration Gy of the vehicle subjected to the control in step 40 and subsequent steps is determined by the yaw rate sensor. 2 is set to the product of the vehicle yaw rate Yr detected by 38 and the vehicle speed V. When a negative determination is made, the control by the routine shown in FIG. Set or maintained in a controlled state.
[0051]
In step 40, the product Gy × V of the lateral acceleration Gy of the vehicle and the vehicle speed V is calculated. In step 50, the absolute value of the product Gy × V is greater than or equal to the first reference value Th1 (positive constant). When a negative determination is made, the process proceeds to step 120, and when an affirmative determination is made, the process proceeds to step 60.
[0052]
In step 60, it is determined whether or not the absolute value of the product Gy × V is equal to or greater than a second reference value Th2 (a positive constant greater than Th1). If a negative determination is made, step 80 is performed. If the determination is affirmative, the turning direction of the vehicle is determined in step 70 based on the steering angle θ, etc., and the target braking pressure Pti (i = rl or rr) for the rear wheels on the turning side is set to zero. Is set.
[0053]
In step 80, an increase amount A of the front wheel braking pressure is calculated from a map corresponding to the graph shown in FIG. 4 based on the absolute value of the product Gy × V. In step 90, the master cylinder pressure Pm is calculated. Based on the map corresponding to the graph shown in FIG. 5, a correction coefficient Kpf is calculated, and in step 100, the pressure increase amount A of the front wheel braking pressure is corrected to the product of the correction coefficient Kpf and the pressure increase amount A. Thus, the corrected front wheel braking pressure increase amount A ′ is calculated.
[0054]
In step 110, the target braking pressures Ptfl and Ptfr of the left and right front wheels are corrected by adding the corrected pressure increase amount A 'to them, and in step 120, the braking pressure of each wheel is changed to the target braking pressure. The hydraulic circuit 22 is controlled to reach Pti, and then the process returns to step 10.
[0055]
Next, the lateral acceleration selection control routine for the vehicle in the illustrated first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 3 is also started by closing an ignition switch not shown in the figure, and is repeated by interruption every predetermined time longer than the control cycle time according to the flowchart shown in FIG. Executed.
[0056]
First, in step 210, a signal indicating the steering angle θ is read. Although not shown in FIG. 3, at the start of control according to the flowchart shown in FIG. 3, the flag Fs is set to 1 prior to step 210, the timer count value Ct is set to 0, and the side of the vehicle Initialization is performed by setting acceleration deviations ΔGya1 (n−1) and ΔGya2 (n−1) to zero.
[0057]
In step 220, whether the steering angle sensor 32, the vehicle speed sensor 34, the lateral acceleration sensor 36, and the yaw rate sensor 38 have no abnormality such as disconnection or short-circuit in a manner known in the art is normal. When a negative determination is made, a normal braking force front / rear wheel distribution control cannot be executed. Therefore, in step 230, the flag Fs is set to 3, and then shown in FIG. When the control by the routine is completed, the braking pressure of each wheel is controlled by the master cylinder 28. When an affirmative determination is made, the routine proceeds to step 240.
[0058]
In step 240, the reference lateral acceleration Gyb of the vehicle is calculated according to the following equation 7 based on the steering angle θ and the vehicle speed V, and the estimated lateral acceleration of the vehicle according to the following equation 8 based on the yaw rate Yr and the vehicle speed V of the vehicle. Gyh is calculated.
Gyb = V²θ / (1 + KhV²) NL (7)
Gyh = Yr × V (8)
[0059]
In step 250, for example, by determining whether or not the state in which the time differential value of the reference lateral acceleration Gyb of the vehicle is equal to or less than the reference value has continued for a predetermined time or longer, the vehicle can substantially reduce the lateral acceleration. 3 is determined. If the determination is negative, the control by the routine shown in FIG. 3 is terminated as it is, and if the determination is affirmative, the routine proceeds to step 260.
[0060]
The determination of whether or not the vehicle is in a steady running state may be performed in any manner known in the art, for example, the time differential value of the estimated lateral acceleration Gyh of the vehicle or the detected vehicle lateral direction. It may be performed based on the time differential value of the acceleration Gy or the detected time differential value of the vehicle yaw rate Yr, or may be performed based on at least two time differential values of the four time differential values. Further, the determination as to whether or not the vehicle is in a steady running state continues for a predetermined time or more when the magnitude of the deviation ΔGyh between the estimated lateral acceleration Gyh of the vehicle and the detected lateral acceleration Gy of the vehicle is equal to or less than a reference value. Whether the deviation ΔGyb between the vehicle's reference lateral acceleration Gyb and the detected vehicle's lateral acceleration Gy is less than or equal to a reference value continues for a predetermined time or more. It may be performed by discrimination.
[0061]
In the illustrated embodiment, it is determined in step 250 whether or not the vehicle is in a steady running state with substantially constant lateral acceleration. In this step, the vehicle is determined. May be modified to determine whether or not the vehicle is in a substantially straight traveling state, that is, whether or not the state in which the lateral acceleration of the vehicle is substantially zero continues for a predetermined time or more. In this case, whether the vehicle is in a substantially straight traveling state is determined by, for example, the absolute value of the estimated lateral acceleration Gyh of the vehicle, the absolute value of the reference lateral acceleration Gyb of the vehicle, or the absolute value of the detected lateral acceleration Gy of the vehicle. Alternatively, it may be performed by determining whether or not the state where the detected absolute value of the yaw rate Yr of the vehicle is equal to or less than the reference value continues for a predetermined time or more, and the absolute value of the steering angle θ of the steered wheel is the reference value. The following state continues for a predetermined time or longer It may take place by which whether the discriminated.
[0062]
In step 260, it is determined whether or not the count value Ct of the timer is less than the reference value T (positive constant). If a negative determination is made, the process proceeds to step 300, where an affirmative determination is made. Sometimes, in step 270, the first deviation magnitude ΔGys1 between the reference lateral acceleration Gyb and the detected lateral acceleration Gy and the second deviation magnitude ΔGys2 between the reference lateral acceleration Gyr and the estimated lateral acceleration Gyh are as follows: Are calculated according to the following equations 9 and 10.
ΔGys1 = | Gyb−Gy | (9)
ΔGys2 = | Gyb−Gyh | (10)
[0063]
In step 280, ΔGya1 (n) and ΔGya2 (n) are set as the current values of accumulated values of the lateral acceleration deviations ΔGys1 and ΔGys2, respectively, and ΔGya1 (n-1) and ΔGya2 (n-1) are respectively set. As the previous values of the integrated values ΔGya1 (n) and ΔGya2 (n), the integrated values ΔGya1 (n) and ΔGya2 (n) are calculated according to the following equations 11 and 12, respectively. In step 290, the count value Ct of the timer is calculated. Is incremented by one.
ΔGya1 (n) = ΔGya1 (n-1) + ΔGys1 (11)
ΔGya2 (n) = ΔGya2 (n-1) + ΔGys2 (12)
[0064]
In step 300, an average value ΔGy1 of the first deviation between the reference lateral acceleration Gyb and the detected lateral acceleration Gy at time T is calculated according to the following equation 13, and at time T. The average value ΔGy2 of the second deviation between the reference lateral acceleration Gyb and the estimated lateral acceleration Gyh is calculated according to the following equation (14).
ΔGy1 = ΔGya1 / T (13)
ΔGy2 = ΔGya2 / T (14)
[0065]
In step 310, it is determined whether or not the average value ΔGy1 of the first deviation is smaller than the average value ΔGy2 of the second deviation. If an affirmative determination is made, step 320 is performed. When the flag Fs is set to 1 and a negative determination is made, the flag Fs is set to 2 at step 330.
[0066]
Thus, according to the first embodiment shown in the figure, in step 240, the reference lateral acceleration Gyb of the vehicle is calculated based on the steering angle θ and the vehicle speed V, and the estimated lateral of the vehicle is calculated based on the yaw rate Yr and the vehicle speed V of the vehicle. When the acceleration Gyh is calculated and it is determined in step 250 that the vehicle is in a steady running state, the lateral acceleration detected as the reference lateral acceleration Gyb at a predetermined time T in steps 260 to 300 is determined. An average value ΔGy1 of the first deviation magnitude with respect to the acceleration Gy and an average value ΔGy2 of the second deviation magnitude between the reference lateral acceleration Gyb and the estimated lateral acceleration Gyh at a predetermined time T are calculated.
[0067]
In Steps 310 to 330, when the average value ΔGy1 of the first deviation magnitude is smaller than the average value ΔGy2 of the second deviation magnitude, it is considered that the reliability of the detected lateral acceleration Gy is high. Therefore, the flag Fs is set to 1, and in steps 30 and 32, the lateral acceleration of the vehicle used for front and rear wheel control of the braking force after step 40 is set to the detected lateral acceleration Gy. On the other hand, when the average value ΔGy1 of the first deviation is equal to or larger than the average value ΔGy2 of the second deviation, it is considered that the estimated lateral acceleration Gyh is highly reliable, so the flag Fs is set to 2. In Steps 30, 34, and 36, the lateral acceleration of the vehicle used for the front and rear wheel distribution control of the braking force after Step 40 is set to the estimated lateral acceleration Gyh.
[0068]
FIG. 6 shows an example of changes in the vehicle lateral acceleration detected value Gy, reference lateral acceleration Gy, and estimated lateral acceleration Gy when the vehicle travels in slalom, and shows the operation of the illustrated first embodiment. Yes.
[0069]
As shown in FIG. 6, if it is determined that the vehicle is in a steady running state until time t6, the average value ΔGy1 of the first deviation ΔGys1 and the second value are calculated every T time until time t6. The magnitude relation of the average value ΔGy2 of the magnitude of the deviation Gys2 is determined, and on the basis of the determination result, the vehicle used for the front and rear wheel distribution control of the braking force in the section from time t1 to time t3 to time t4 is determined. The detected value Gy is selected as the lateral acceleration, the estimated lateral acceleration Gyh is selected in other sections, and the last selected estimated lateral acceleration Gyh is selected after time t5.
[0070]
Therefore, according to the illustrated first embodiment, the lateral acceleration Gy detected by the lateral acceleration sensor 36 and the lateral acceleration of the vehicle based on the reliable detection value of the yaw rate Yr detected by the yaw rate sensor 38 are determined. Since the front / rear wheel distribution control of the braking force is executed, the front / rear wheels are controlled with higher accuracy than the case where the front / rear wheel distribution control of the braking force is executed only based on the lateral acceleration Gy detected by the lateral acceleration sensor 36. The distribution of the braking force can be controlled.
[0071]
Further, according to the illustrated first embodiment, for example, the lateral acceleration of the vehicle is detected by two lateral acceleration sensors, and the reliability of both is determined by constantly comparing the detected values frequently. Compared to the above, the calculation load of the control device can be reduced.
[0072]
Further, according to the illustrated first embodiment, the cycle time of the vehicle lateral acceleration selection control according to the flowchart shown in FIG. 3 is longer than the cycle time of the braking force front and rear wheel distribution control according to the flowchart shown in FIG. Since each step after step 260 is executed only when the vehicle is in a steady running state, the calculation load of the control device can also be reduced by this.
[0073]
According to the illustrated first embodiment, the average value of the magnitudes of the first deviations between the reference lateral acceleration Gyb and the detected lateral acceleration Gy at a predetermined time T when the vehicle is in a steady running state. Since ΔGy1 and an average value ΔGy2 of the second deviation between the reference lateral acceleration Gyb and the estimated lateral acceleration Gyh at a predetermined time T are calculated and the average values thereof are compared, the reference lateral acceleration Gyb and Compared to the case where the magnitude of the first deviation from the detected lateral acceleration Gy and the magnitude of the second deviation between the reference lateral acceleration Gyb and the estimated lateral acceleration Gyh are compared, the reliability of any detected value It is possible to determine with high accuracy whether the property is high.
[0074]
According to the illustrated first embodiment, the target braking pressure Pti of each wheel is calculated based on the driver's braking operation amount (master cylinder pressure Pm) in step 20, and in step 40, the vehicle's target braking pressure Pti is calculated. When the product Gy × V of the lateral acceleration Gy and the vehicle speed V is calculated and the absolute value of the product Gy × V is not less than the first reference value Th1 and less than the second reference value Th2, the steps 50 and 60 are performed. A positive determination and a negative determination are made, respectively, and in steps 80 to 110, the pressure increase amount A ′ of the front wheel is calculated so as to increase as the absolute value of the product Gy × V increases, thereby increasing the product Gy × V. The braking pressure of the front wheels is increased so as to increase as the speed increases.
[0075]
Accordingly, the larger the product Gy × V is, the more the front-rear wheel distribution ratio of the braking force becomes closer to the front wheels, so that the vehicle yaw rate can be prevented from increasing in the turning direction, and the vehicle can be braked and turned stably. Also, since the braking force of the front wheels is increased instead of reducing the braking force of the rear wheels, it is possible to surely prevent the deceleration of the vehicle from being lowered, thereby reducing the deceleration of the vehicle. This can surely prevent the driver from feeling uncomfortable or dissatisfied.
[0076]
Although the braking force of the entire vehicle increases due to the increase of the braking force of the front wheels, if the deceleration of the vehicle becomes too high due to this, the driver reduces the amount of depression of the brake pedal and the braking force of the entire vehicle. Therefore, the increase in the braking force of the front wheels does not prevent the driver from achieving the vehicle deceleration desired by the driver.
[0077]
When the absolute value of the product Gy × V is greater than or equal to the second reference value Th2, an affirmative determination is made in steps 50 and 60, and the absolute value of the product Gy × V is large in steps 80 to 110. Thus, the front wheel pressure increase amount A 'is calculated so as to increase, so that as the product Gy × V increases, the front wheel braking pressure increases so as to increase. The target braking pressure is set to 0, and the braking pressure on the inside of the turn is fully reduced in step 120, whereby the braking force of the rear wheels is reduced.
[0078]
Therefore, when the absolute value of the product Gy × V is greater than or equal to the second reference value Th2, that is, in a situation where the yaw rate of the vehicle is likely to increase further, the absolute value of the product Gy × V is greater than or equal to the first reference value Th1. Compared to the case where it is less than the second reference value Th2, the front-rear wheel distribution ratio of the braking force is even closer to the front wheels, so the vehicle yaw rate is prevented from increasing in the turning direction and the vehicle is stabilized. The braking force of the front wheel is increased and the braking force of the rear wheel is reduced, so that the braking force of the entire vehicle becomes excessive and the deceleration of the vehicle becomes excessive. It can be surely prevented.
[0079]
Further, according to the illustrated embodiment, in step 90, the correction coefficient Kpf is calculated so as to decrease as the master cylinder pressure Pm increases. In step 100, the increase amount A of the front wheel braking pressure is increased with the correction coefficient Kpf. Since the amount of braking operation by the driver is high and the braking force of the wheel by the driver's braking operation is high, the front wheel braking pressure is increased, so that the front wheel braking pressure is increased. It is possible to reliably reduce the possibility that the turning performance of the vehicle will deteriorate due to excessive braking force and a decrease in lateral force of the front wheels.
[0080]
Further, according to the illustrated embodiment, since only the braking pressure of the rear inner wheel is reduced in step 70, the deceleration of the vehicle is lower than when the braking pressure of the left and right rear wheels is reduced. The fear can be reduced, and an anti-spin moment due to the difference in braking force between the left and right rear wheels can be applied to the vehicle, thereby effectively reducing the possibility that the vehicle will be in a spin state.
[0081]
In the embodiment shown in the drawing, the target braking pressure of the turning inner rear wheel is set to 0 in Step 70 because the electromagnetic on-off valve for pressure reduction of a general braking device is opened and closed intermittently. This is because if the brake pressure of the rear wheel is to be reduced, abnormal noise is likely to occur due to the intermittent opening and closing.
[0082]
Further, according to the illustrated embodiment, when the absolute value of the product Gy × V is equal to or larger than the second reference value Th2, the absolute value of the product Gy × V is smaller than the second reference value, Since the rate of increase of the pressure increase amount A with respect to the absolute value of the product Gy × V is small, the braking force of the front wheel becomes excessive and the lateral force of the front wheel becomes excessive in a region where the product Gy × V is larger than the second reference value Th2. It is possible to reduce the possibility that the turning performance of the vehicle will deteriorate due to the decrease.
[0083]
In the illustrated embodiment, prior to step 40, it is determined whether or not the front and rear wheel distribution control of the braking force is permitted, the braking operation by the driver is performed, and the road surface is It may be modified so that each step after step 40 is executed only when the vehicle is not turning off and the vehicle is in a turning state, in which case the permission determination of the front and rear wheel distribution control of the braking force is not performed. Compared to the above, it is possible to reliably reduce the possibility that the front and rear wheel distribution control of the braking force will be performed unnecessarily, and the front and rear wheel distribution control of the braking force is executed particularly in a situation where the road surface is a straddling road. Therefore, it is possible to reliably prevent the behavior of the vehicle from deteriorating.
[0084]
Second embodiment
FIG. 7 is a schematic configuration diagram showing a second embodiment of the vehicle control apparatus according to the present invention configured to control the steering angle of the rear wheel based on the yaw rate of the vehicle, and FIG. 8 is a rear view in the second embodiment. It is a flowchart which shows a wheel steering angle control routine. In FIG. 7, the members corresponding to those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG. In FIG. 8, steps corresponding to the steps shown in FIG. 3 are assigned step numbers obtained by adding 200 to the step numbers given in FIG.
[0085]
In this second embodiment, the left and right rear wheels 10RL and 10RR are steered via tie rods 46L and 46R by the rack and pinion type power steering device 44 of the rear wheel steering device 42, and rear wheel steering is performed. The device 42 is controlled by the electronic control unit 30. The electronic control unit 30 calculates the reference yaw rate Yrb of the vehicle based on the steering angle θ and the vehicle speed V, so that the magnitude of the deviation between the reference yaw rate Yrb and the vehicle yaw rate is reduced regardless of the driver's steering operation. Controls the rudder angle of the rear wheels.
[0086]
In particular, the electronic control unit 30 calculates the reference yaw rate Yrb of the vehicle based on the steering angle θ and the vehicle speed V according to the flowchart shown in FIG. 8 as described later, and the estimated yaw rate of the vehicle based on the lateral acceleration Gy and the vehicle speed V of the vehicle. Yrh is calculated, and the magnitude of deviation between the reference yaw rate Yrb and the detected vehicle yaw rate Yr and the magnitude of deviation between the reference yaw rate Yrb and the estimated yaw rate Yrh when the vehicle is in a steady running state are compared. The yaw rate Yr or estimated yaw rate Yrh having a smaller size, that is, a higher reliability is used as the vehicle yaw rate Yr in the rear wheel steering control.
[0087]
Next, a rear wheel steering angle control routine in the illustrated second embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 8 is started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals.
[0088]
First, at step 410, a signal indicating the steering angle θ is read. Although not shown in FIG. 8, as in the case of the first embodiment, the flag Fs is set to 1 prior to step 410 at the start of control according to the flowchart shown in FIG. Initialization is performed by setting Ct to 0 and setting the vehicle yaw rate deviations ΔYra1 (n-1) and ΔYr2 (n-1) to 0.
[0089]
In step 420, whether the steering angle sensor 32, the vehicle speed sensor 34, the lateral acceleration sensor 36, and the yaw rate sensor 38 are normal without any abnormality such as disconnection or short-circuit as is known in the art. If the determination is negative and the negative determination is made, normal rear wheel steering control cannot be executed, so the flag Fs is set to 3 in step 430, and then the routine shown in FIG. When the control by is terminated, the steering of the rear wheels is prohibited. When an affirmative determination is made, the routine proceeds to step 440.
[0090]
In step 440, the yaw rate Yrb of the vehicle is calculated according to the following equation 15 based on the steering angle θ and the vehicle speed V, and the estimated yaw rate Yrh of the vehicle is calculated according to the following equation 16 based on the lateral acceleration Gy and the vehicle speed V of the vehicle. Calculated.
Yrb = Vθ / (1 + KhV²) NL (15)
Yrh = Gy / V (16)
[0091]
In step 450, for example, by determining whether or not the state in which the time differential value of the reference yaw rate Yrb of the vehicle is equal to or less than the reference value continues for a predetermined time or longer, the vehicle has a substantially constant yaw rate. Whether or not the vehicle is in the steady running state is determined. When a negative determination is made, the control according to the routine shown in FIG. 8 is terminated, and when an affirmative determination is made, the process proceeds to step 460.
[0092]
The determination of whether or not the vehicle is in a steady running state may be made in any manner known in the art, for example, the time derivative of the estimated yaw rate Yrh of the vehicle or the detected yaw rate Yr of the vehicle. Or the detected time differential value of the lateral acceleration Gy of the vehicle, or based on at least two time differential values of the four time differential values. Further, the determination as to whether or not the vehicle is in a steady running state is made by continuing a state where the magnitude of the deviation ΔYrh between the estimated yaw rate Yrh of the vehicle and the detected yaw rate Yr of the vehicle is equal to or less than a reference value for a predetermined time or longer. Or whether the deviation ΔYrb between the vehicle reference yaw rate Yrb and the detected vehicle yaw rate Yr is less than or equal to the reference value continues for a predetermined time or more. May be.
[0093]
In the illustrated embodiment, in step 450, it is determined whether or not the vehicle is in a steady running state at a substantially constant yaw rate. In this step, the vehicle is It may be modified so as to determine whether or not the vehicle is in a substantially straight running state, that is, whether or not the vehicle's yaw rate is substantially zero for more than a predetermined time. In this case, whether the vehicle is in a substantially straight traveling state is determined by, for example, the absolute value of the estimated yaw rate Yrh of the vehicle, the absolute value of the reference yaw rate Yrb of the vehicle, the absolute value of the detected yaw rate Yr of the vehicle, or the detected vehicle. The state where the absolute value of the lateral acceleration Gy of the steering wheel is not more than the reference value may be determined by determining whether or not the state continues for a predetermined time or more, and the absolute value of the steering angle θ of the steered wheels is not more than the reference value Is a predetermined time It may be performed by determining whether the discrimination has been on continuously.
[0094]
In step 460, it is determined whether or not the count value Ct of the timer is less than the reference value T (positive constant). If a negative determination is made, the process proceeds to step 500, where an affirmative determination is made. Sometimes, in step 470, the first deviation magnitude ΔYrs1 between the reference yaw rate Yrb and the detected yaw rate Yr and the second deviation magnitude ΔYrs2 between the reference yaw rate Yrr and the estimated yaw rate Yrh are expressed by the following equations 17 and 17, respectively. 18 is calculated.
ΔYrs1 = | Yrb−Yr | (17)
ΔYrs2 = | Yrb−Yrh | (18)
[0095]
In step 480, ΔYra1 (n) and ΔYra2 (n) are set as current values of accumulated values of yaw rate deviations ΔYrs1 and ΔYrs2, respectively, and ΔYra1 (n-1) and ΔYra2 (n-1) are respectively integrated. As the previous values of the values ΔYra1 (n) and ΔYra2 (n), the integrated values ΔYra1 (n) and ΔYra2 (n) are calculated according to the following equations 19 and 20, respectively. In step 490, the timer count value Ct is calculated. Incremented by one.
ΔYra1 (n) = ΔYra1 (n-1) + ΔYrs1 (19)
ΔYra2 (n) = ΔYra2 (n-1) + ΔYrs2 (20)
[0096]
In step 500, an average value ΔYr1 of the magnitude of the first deviation between the reference yaw rate Yrb at T time and the detected yaw rate Yr is calculated according to the following equation 21, and the reference at T time is obtained. An average value ΔYr2 of the magnitude of the second deviation between the yaw rate Yrb and the estimated yaw rate Yrh is calculated according to Equation 22 below.
ΔYr1 = ΔYra1 / T (21)
ΔYr2 = ΔYra2 / T (22)
[0097]
In step 510, it is determined whether or not the average value ΔYr1 of the first deviation magnitude is smaller than the average value ΔYr2 of the second deviation magnitude. If an affirmative determination is made, step 520 is performed. When the flag Fs is set to 1 and the determination is negative, the flag Fs is set to 2 at step 530.
[0098]
In step 540, it is determined whether or not the flag Fs is 1. If an affirmative determination is made in step 550, the yaw rate Yr of the vehicle used for the rear wheel steering control in step 570 is determined as the yaw rate. When the yaw rate Yr detected by the sensor 38 is set and a negative determination is made, in step 560, the yaw rate Yr of the vehicle used for the rear wheel steering control in step 570 is detected by the lateral acceleration sensor 36. A value Gy / V obtained by dividing the lateral acceleration Gy by the vehicle speed V is set.
[0099]
In step 570, based on the deviation between the reference yaw rate Yrb of the vehicle and the detected yaw rate Yr, the rear wheel target rudder angle is calculated to reduce the magnitude of the deviation, and the rear wheel rudder angle is the target. Rear wheel steering control is executed in which the steering angle of the rear wheels is controlled so that the steering angle becomes the same, and then the process returns to step 410.
[0100]
Thus, according to the second embodiment, in step 440, the yaw rate Yrb of the vehicle is calculated based on the steering angle θ and the vehicle speed V, and the estimated yaw rate Yrh of the vehicle is calculated based on the lateral acceleration Gy and the vehicle speed V of the vehicle. When it is calculated and it is determined in step 450 that the vehicle is in a steady running state, in steps 460 to 500, the reference yaw rate Yr at the predetermined time T and the detected yaw rate Yr An average value ΔYr1 of the magnitude of one deviation and an average value ΔYr2 of the magnitude of the second deviation between the reference yaw rate Yrb and the estimated yaw rate Yrh at a predetermined time T are calculated.
[0101]
In steps 510 to 530, if the average value ΔYr1 of the first deviation magnitude is smaller than the average value ΔYr2 of the second deviation magnitude, it is considered that the detected yaw rate Yr is highly reliable. The flag Fs is set to 1, and in steps 540 and 550, the yaw rate of the vehicle used for the rear wheel steering angle control in step 570 is set to the detected yaw rate Yr. On the other hand, when the average value ΔYr1 of the first deviation magnitude is equal to or larger than the average value ΔYr2 of the second deviation magnitude, it is considered that the estimated yaw rate Yrh is highly reliable, so the flag Fs is set to 2. In steps 540 and 560, the yaw rate of the vehicle used for the rear wheel steering angle control in step 570 is set to the estimated yaw rate Yrh.
[0102]
Therefore, according to the second embodiment shown in the figure, the lateral acceleration Gy detected by the lateral acceleration sensor 36 and the yaw rate Yr detected by the yaw rate sensor 38 are later determined based on the reliable yaw rate of the vehicle. Since the wheel steering angle control is executed, it is possible to control the steering angle of the rear wheels with higher accuracy than in the case where the rear wheel steering angle control is executed only based on the yaw rate Yr detected by the yaw rate sensor 38. Thus, the actual yaw rate of the vehicle can be accurately controlled to the target reference yaw rate Yrh.
[0103]
Further, according to the second embodiment shown in the figure, for example, the yaw rate of the vehicle is detected by two yaw rate sensors, and the detected values are constantly compared frequently to determine the reliability of both. Thus, the calculation load of the control device can be reduced.
[0104]
In the illustrated second embodiment, the yaw rate selection control routine in steps 420 to 560 is executed as a part of the rear wheel steering angle control routine. As in the case of, the yaw rate selection control routine may be modified to be executed by a routine independent of the rear wheel steering angle control routine. In that case, the cycle time of the yaw rate selection control may be longer than the cycle time of the rear wheel steering angle control, and each step after step 360 is executed only when the vehicle is in a steady running state. Can be further reduced.
[0105]
Further, according to the second embodiment shown in the figure, as in the case of the first embodiment described above, the reference yaw rate Yrb at the predetermined time T and the detected yaw rate Yr when the vehicle is in the steady running state An average value ΔYr1 of the first deviation magnitude and an average value ΔYr2 of the second deviation magnitude between the reference yaw rate Yrb and the estimated yaw rate Yrh at a predetermined time T are calculated, and the average values are compared. Therefore, as compared with the case where the magnitude of the first deviation between the reference yaw rate Yrb and the detected yaw rate Yr and the magnitude of the second deviation between the reference yaw rate Yrb and the estimated yaw rate Yrh are compared, It is possible to determine with high accuracy whether the reliability of the detection value is high.
[0106]
Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.
[0107]
For example, in the first embodiment described above, the vehicle control device is a braking force control device that performs front / rear wheel distribution control of the braking force during turning braking based on the lateral acceleration of the vehicle, and the second embodiment described above. In this case, the vehicle control device is a rear wheel steering angle control device that controls the steering angle of the rear wheel based on the yaw rate of the vehicle, but the vehicle control device of the present invention controls the vehicle based on the lateral acceleration or the yaw rate of the vehicle. The present invention may be applied to any vehicle control device.
[0108]
In the first and second embodiments described above, the vehicle speed V is a value detected by a vehicle speed sensor. The vehicle speed is based on the wheel speed of each wheel. The calculation may be performed in any known manner.
[0109]
In step 310 of the first embodiment described above, it is determined whether or not the average value ΔGy1 of the first deviation magnitude is smaller than the average value ΔGy2 of the second deviation magnitude. However, it may be modified so that it is determined whether or not the average value ΔGy1 of the first deviation magnitude is equal to or smaller than the average value ΔGy2 of the second deviation magnitude. Similarly, in step 510 of the second embodiment described above, it is determined whether or not the average value ΔYr1 of the first deviation magnitude is smaller than the average value ΔYr2 of the second deviation magnitude. However, it may be modified so as to determine whether or not the average value ΔYr1 of the first deviation magnitude is equal to or less than the average value ΔYr2 of the second deviation magnitude.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle control device according to the present invention configured to perform front and rear wheel distribution control of braking force during turning braking based on lateral acceleration of a vehicle.
FIG. 2 is a flowchart showing a front / rear wheel distribution control routine of braking force in the first embodiment.
FIG. 3 is a flowchart showing a lateral acceleration selection control routine of the vehicle in the first embodiment.
FIG. 4 is a graph showing a relationship between an absolute value of a product Gy × V of a lateral acceleration Gy and a vehicle speed V of a vehicle and a braking pressure increase amount A of a front wheel.
FIG. 5 is a graph showing a relationship between a master cylinder pressure Pm and a correction coefficient Kpf.
FIG. 6 shows an example of changes in detected lateral acceleration Gy, reference lateral acceleration Gy, and estimated lateral acceleration Gy of the vehicle when the vehicle travels in slalom, and also shows the operation of the illustrated first embodiment. It is a graph.
FIG. 7 is a schematic configuration diagram showing a second embodiment of the vehicle control device according to the present invention configured to control the steering angle of the rear wheel based on the yaw rate of the vehicle.
FIG. 8 is a flowchart showing a rear wheel steering angle control routine in the second embodiment.
[Explanation of symbols]
10FR ~ 10RL ... wheel
20 ... braking device
28 ... Master cylinder
30 ... Electronic control unit
32 ... Steering angle sensor
34 ... Vehicle speed sensor
36 ... Lateral acceleration sensor
38 ... Yaw rate sensor
40 ... Pressure sensor
42. Rear wheel steering device

Claims (3)

A vehicle control device for controlling a vehicle based on at least the lateral acceleration of the vehicle, and a vehicle speed detecting means, a steering angle detecting means for detecting a steering angle of a steered wheel, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, A yaw rate sensor for detecting a yaw rate, means for calculating a reference lateral acceleration of the vehicle based on the vehicle speed detected by the vehicle speed detection means and the steering angle detected by the steering angle detection means, and detected by the vehicle speed detection means Means for calculating the estimated lateral acceleration of the vehicle based on the measured vehicle speed and the yaw rate detected by the yaw rate sensor, the reference lateral acceleration and the lateral acceleration detected by the lateral acceleration sensor when the vehicle is in a steady running state, The comparison means for comparing the first deviation of the first deviation and the second deviation of the reference lateral acceleration and the estimated lateral acceleration, and the comparison result of the comparison means And a selection means for selecting a detection value of the lateral acceleration sensor or the yaw rate sensor corresponding to the smaller deviation of the first and second deviations, and the detection selected by the selection means. A vehicle control device that controls a vehicle based on a lateral acceleration of the vehicle based on a value. At least a vehicle control device that controls a vehicle based on a yaw rate of the vehicle, a vehicle speed detection unit, a steering angle detection unit that detects a steering angle of a steering wheel, a lateral acceleration sensor that detects a lateral acceleration of the vehicle, and a yaw rate of the vehicle A yaw rate sensor for detecting the vehicle, a means for calculating a reference yaw rate of the vehicle based on the vehicle speed detected by the vehicle speed detection means and the steering angle detected by the steering angle detection means, and detected by the vehicle speed detection means Means for calculating an estimated yaw rate of the vehicle based on a vehicle speed and a lateral acceleration detected by the lateral acceleration sensor; and a first yaw rate detected by the reference yaw rate and the yaw rate detected by the yaw rate sensor when the vehicle is in a steady running state. Comparison means for comparing a deviation and a second deviation between the reference yaw rate and the estimated yaw rate; and the comparison means Selection means for selecting a detection value of the lateral acceleration sensor or the yaw rate sensor corresponding to the smaller deviation of the first and second deviations based on the comparison result, and selected by the selection means A vehicle control apparatus for controlling a vehicle based on a yaw rate of the vehicle based on the detected value. Said comparing means for comparing said steering angle to determine the straight running condition of the vehicle based on the steering angle detected by the detecting means, said first and second deviations when the vehicle is judged to be in a straight running state The vehicle control device according to claim 1, wherein:

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