JP3705077B2 - Vehicle motion control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motion control device for a vehicle such as an automobile, and more particularly to a motion control device that stabilizes the motion of a vehicle by applying a braking force to wheels based on the running state of the vehicle.
[0002]
[Prior art]
As one of motion control devices for vehicles such as automobiles, for example, as described in Japanese Patent Application Laid-Open No. 9-109851 filed by the applicant of the present application, the vehicle spin state is detected, and the vehicle spin state is detected. Is a behavior control device that applies a braking force to a wheel and applies a yaw moment in a spin suppression direction to the vehicle to suppress spin, and the generation speed of the braking force applied to the wheel as the execution time of the spin suppression control increases. Conventionally, a behavior control apparatus configured to reduce the above is known.
[0003]
According to such a behavior control device, the generation rate of the yaw moment in the spin suppression direction is reduced as the execution time of the spin suppression control is longer. Therefore, the behavior caused by the excessive yaw moment in the spin suppression direction being applied to the vehicle. The possibility of control hunting can be reduced.
[0004]
[Problems to be solved by the invention]
In general, in a motion control device that controls braking force such as the behavior control device described above, a target control amount that stabilizes the motion of the vehicle is calculated based on the running state of the vehicle, and each wheel is controlled based on the target control amount. The target slip ratio is calculated, and the braking force of each wheel is controlled to increase or decrease so that the slip ratio of each wheel becomes the target slip ratio.
[0005]
However, the braking force increase / decrease gradient in the motion control is uniquely set in advance with respect to the target slip ratio. For example, behavior control for stabilizing the turning behavior of the vehicle and roll suppression control for suppressing excessive roll of the vehicle body. Depending on the running condition of the vehicle, the braking force uniquely set in advance for the target slip ratio, as in the case where the actual road surface friction coefficient is significantly different from the assumed road friction coefficient. The increase / decrease gradient does not match the actual situation of the vehicle, so the acceleration / deceleration of the vehicle changes rapidly due to the sudden increase / decrease in braking force due to motion control, resulting in the vehicle's pitching behavior and the wheel The ground contact load or the like of the vehicle may change abruptly, and therefore the vehicle motion may not be stabilized effectively.
[0006]
The present invention has been made in view of the above-described problems in the conventional motion control apparatus in which the increase / decrease gradient of the braking force in motion control is uniquely set in advance with respect to the target slip ratio. The main problem is to prevent the vehicle acceleration / deceleration from changing suddenly when there is a possibility that the stability of the vehicle will decrease due to the increase / decrease of the braking force by the motion control. It is to ensure stabilization.
[0007]
[Means for Solving the Problems]
  According to the present invention, the main problem described above is the vehicle motion control device that performs motion control to stabilize the motion of the vehicle by applying braking force to the wheel based on the configuration of claim 1, that is, the running state of the vehicle. InBehavior control means for stabilizing the turning behavior of the vehicle, roll suppression control means for suppressing excessive roll of the vehicle body, target control amount for each wheel by the behavior control means, and target control for each wheel by the roll suppression control means Means for calculating a final target control amount for each wheel based on the amount, means for controlling motion by controlling the braking force of each wheel based on the final target control amount, andDetermining means for determining the possibility that the stability of the vehicle will decrease due to the increase or decrease of the braking force due to the motion control, and the braking force based on the motion control when the determination means determines that there is a possibility of the decrease in the stability of the vehicle ofAt least decreaseHas a means to reduce the speed.The determination means determines that the stability of the vehicle may be lowered when the roll suppression control is executed by the roll suppression control means.Vehicle motion control device characterized byAlternatively, the vehicle motion control device for controlling the motion of the vehicle by stabilizing the motion of the vehicle by applying a braking force to the wheel based on the running state of the vehicle to stabilize the turning behavior of the vehicle. Based on the behavior control means, the roll suppression control means that suppresses excessive roll of the vehicle body, the target control amount of each wheel by the behavior control means, and the target control amount of each wheel by the roll suppression control means, the final control of each wheel Means for calculating a desired target control amount, means for performing motion control by controlling the braking force of each wheel based on the final target control amount, and a vehicle caused by increase / decrease in braking force by the motion control Determining means for determining the possibility that the stability of the vehicle will be reduced, and means for reducing at least the rate of decrease in the braking force by the motion control when the determination means determines that there is a possibility that the stability of the vehicle will be reduced. And the determination means determines that there is a possibility that the stability of the vehicle is lowered when the magnitude of the state quantity indicating the degree of roll of the vehicle body exceeds a reference value. apparatusAchieved by:
[0008]
  According to the configuration of claim 1 above,When roll suppression control is being performed by the roll suppression control means, it is determined that the stability of the vehicle may be reduced. According to the configuration of claim 2, the state quantity indicating the degree of roll of the vehicle body is determined. When the size exceeds the reference value, it is determined that the stability of the vehicle may decrease,There is a risk that the stability of the vehicle will decrease due to the increase or decrease of braking force due to motion controlDeterminedSometimes the braking force by motion controlAt least decreaseSince the speed is reduced, the acceleration / deceleration of the vehicleat leastRapidlyDecreaseTo avoid braking force by motion control.Sudden decreaseIt is prevented that the stability of the vehicle is lowered due to the above.
[0010]
  AlsoClaim1 andAccording to the configuration of 2, the control of each wheel is based on the final target control amount of each wheel calculated based on the target control amount of each wheel by the behavior control means and the target control amount of each wheel by the roll suppression control means. Because the power is controlled, not only when there is a possibility that the stability of the vehicle may be lowered due to the increase or decrease of the braking force due to the roll suppression control, but also due to the increase or decrease of the braking force due to the behavior control or roll suppression control Even when there is a possibility that the stability of the vehicle is lowered, the speed of changing the braking force is surely lowered.
[0012]
In general, in a situation where roll restraint control by the roll restraint control means is being executed, the roll amount of the vehicle body is high, so if the braking force is suddenly increased or decreased by roll restraint control, the vehicle acceleration / deceleration changes rapidly. As a result, the stability of the vehicle tends to decrease.
[0013]
  Claims above1With this configuration, it is determined that there is a possibility that the stability of the vehicle may be lowered when the roll suppression control is being executed by the roll suppression control means. A decrease in vehicle stability is reliably prevented.
[0015]
  Also aboveClaim2With this configuration, it is determined that there is a possibility that the stability of the vehicle may decrease when the magnitude of the state quantity indicating the degree of the roll of the vehicle body exceeds the reference value. In this case, it is possible to reliably prevent the stability of the vehicle from being lowered due to the increase or decrease of the braking force due to the motion control.
  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration according to claim 1 or 2, the means for reducing at least the reduction rate of the braking force by the motion control is the motion control. It is comprised so that only the decreasing speed of the braking force by may be reduced.
  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1 or 2, the means for calculating the final target control amount of each wheel is provided for each wheel. The larger value of the target control amount by the behavior control means and the target control amount by the roll suppression control means is calculated as the final target control amount.
[0017]
[Preferred embodiment of the problem solving means]
  The present inventionOneAccording to one preferred embodiment, the above claims1 orIn the configuration of 2, the behavior control means applies the braking force corresponding to the value indicating the degree of vehicle spin to at least the outer front wheel when the value indicating the degree of vehicle spin exceeds the reference value. Configured to stabilize (preferred embodiment1).
[0018]
  According to another preferred embodiment of the invention, the above claims1 orIn the second configuration, when the value indicating the degree of drifting out of the vehicle exceeds the reference value, the behavior control means applies at least a braking force corresponding to the value indicating the degree of drifting out of the vehicle to the rear inner wheel. Configured to stabilize turning behavior (preferred embodiment2).
[0019]
  According to another preferred embodiment of the invention, the above claims1 orIn the configuration of 2, the roll suppression control means applies at least a braking force corresponding to the value indicating the degree of roll of the vehicle body to the turning outer front wheel when the value indicating the degree of roll of the vehicle body exceeds a reference value. Configured to suppress excessive rolls (preferred embodiment3).
[0021]
  According to another preferred embodiment of the invention, the above claims2In this configuration, the state quantity indicating the degree of roll of the vehicle body is configured to be the lateral acceleration of the vehicle (preferred embodiment4).
[0022]
  According to another preferred embodiment of the invention, the above claims2In this configuration, the state quantity indicating the degree of roll of the vehicle body is configured to be the yaw rate of the vehicle (preferred embodiment5).
[0023]
  According to another preferred embodiment of the invention, the above claims2In this configuration, the determination means reduces the stability of the vehicle when the lateral acceleration of the vehicle exceeds the corresponding reference value and the yaw rate of the vehicle exceeds the corresponding reference value. Configured to determine that there is a fear (preferred embodiment6).
[0024]
  According to another preferred embodiment of the invention, the above claims2In this configuration, the state quantity indicating the degree of roll of the vehicle body is configured to be the longitudinal acceleration of the vehicle (preferred embodiment7).
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0026]
FIG. 1 is a schematic diagram showing a preferred embodiment of a vehicle motion control apparatus according to the present invention.
[0027]
In FIG. 1, 10FL and 10FR respectively indicate the left and right front wheels of the vehicle 12, and 10RL and 10RR respectively indicate the left and right rear wheels which are drive wheels of the vehicle. The left and right front wheels 10FL and 10FR, which are both driven wheels and steering wheels, are driven through tie rods 18L and 18R by a rack and pinion type power steering device 16 driven in response to the steering of the steering wheel 14 by the driver. Steered.
[0028]
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 various valve devices such as an oil reservoir, an oil pump, and a pressure increasing / decreasing control valve for increasing / decreasing the pressure in the wheel cylinder. Normally, it is controlled by a master cylinder 28 that is driven in accordance with the depression operation of the brake pedal 26 by the driver, and the pressure increase / decrease control valve is duty ratio controlled by an electric control device 30 as will be described in detail later if necessary. Is controlled by
[0029]
Each of the wheels 10FR to 10RL is provided with wheel speed sensors 32FR to 32RL for detecting the wheel speed Vwi (i = fr, fl, rr, rl) of the corresponding wheel as a peripheral speed, and a steering column to which the steering wheel 14 is connected. Is provided with a steering angle sensor 34 for detecting the steering angle θ.
[0030]
The vehicle 12 is provided with a yaw rate sensor 36 for detecting the yaw rate γ of the vehicle, a longitudinal acceleration sensor 38 for detecting the longitudinal acceleration Gx, and a lateral acceleration sensor 40 for detecting the lateral acceleration Gy. The steering angle sensor 34, the yaw rate sensor 36, and the lateral acceleration sensor 40 detect the steering angle, the yaw rate, and the lateral acceleration, respectively, with the left turning direction of the vehicle being positive.
[0031]
As shown in the figure, a signal indicating the wheel speed Vwi detected by the wheel speed sensors 32FR to 32RL, a signal indicating the steering angle θ detected by the steering angle sensor 34, a signal indicating the yaw rate γ detected by the yaw rate sensor 36, A signal indicating the longitudinal acceleration Gx detected by the acceleration sensor 38 and a signal indicating the lateral acceleration Gy detected by the lateral acceleration sensor 40 are input to the electric control device 30.
[0032]
Although not shown in detail in the figure, the electric control device 30 has, for example, a general configuration in which a CPU, a ROM, a RAM, and an input / output port device are connected to each other by a bidirectional common bus. Includes a microcomputer.
[0033]
The electric control device 30 follows a flowchart shown in FIGS. 2 to 4 as will be described later, and the spin state amount SS indicating the degree of vehicle spin based on the running state of the vehicle and the drift-out indicating the degree of vehicle drift-out. The state quantity DS is calculated, and the target braking force Fbsi (i = fr, fl, rr, rl) of each wheel for behavior control is calculated based on the spin state quantity SS and the drift-out state quantity DS.
[0034]
Further, the electric control device 30 calculates a roll evaluation value RV indicating the degree and direction of the roll of the vehicle body, determines whether roll suppression control should be executed based on the lateral acceleration Gy of the vehicle and the yaw rate γ of the vehicle, When roll suppression control is to be executed, a roll suppression control amount B is calculated based on the absolute value of the roll evaluation value RV, and the target braking force Fbri (i = fr, fl) of each wheel of roll suppression control is calculated based on the roll suppression control amount B. , Rr, rl).
[0035]
Further, the electric control device 30 calculates the target braking force Fbti (i = fr, fl, rr, rl) of each wheel based on the target braking force Fbsi for behavior control and the target braking force Fbri for roll suppression control. The target slip rate Rsti (i = fr, fl, rr, rl) of each wheel is calculated based on the power Fbti, and the slip rate of each wheel is controlled by controlling the pressure increasing / reducing control valve of each wheel based on the target slip rate Rsti. The braking force is controlled so as to achieve the target slip ratio, thereby performing motion control that stabilizes the motion of the vehicle.
[0036]
Further, the electric control device 30 determines whether or not there is a possibility that the stability of the vehicle is lowered due to increase or decrease of the braking force by the motion control, and when there is no possibility that the stability of the vehicle is lowered ( During normal operation, the braking pressure of each wheel is controlled to increase or decrease with a relatively large increase / decrease gradient so that the braking force of each wheel can be increased / decreased with good responsiveness. The braking pressure of each wheel is controlled to increase or decrease with an increasing / decreasing gradient that is smaller than that of time.
[0037]
Next, the main routine of the motion control in the illustrated 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.
[0038]
First, in step 10, a signal indicating the wheel speed Vwi is read. When the control according to the flowchart shown in FIG. 2 is started, the roll angular velocity estimated value Rr, the roll angle estimated value R, and the roll evaluation value RV are reset to 0 as initial values at the start of control prior to step 10.
[0039]
In step 20, the target braking force Fbsi (i = fr, fl, rr, rl) of each wheel for behavior control is calculated according to the routine shown in FIG. 3, and in step 50, it is shown in FIG. The target braking force Fbri (i = fr, fl, rr, rl) of each wheel for roll suppression control is calculated according to the routine.
[0040]
In step 70, the target braking force Fbti (i = fr, fl, rr, rl) of each wheel is calculated according to the following equation 1 with MAX () being the larger value in parentheses, and in step 80 Here, based on the target braking force Fbti, the target slip ratio Rsti (i = fr, fl, rr, rl) of each wheel for achieving the target braking force Fbti from the map corresponding to the graph shown in FIG. Calculated.
Fbti = MAX (Fbsi, Fbri) (1)
[0041]
In step 90, the vehicle body speed Vb is calculated in a manner known in the art based on the wheel speed Vwi of each wheel, and the target wheel speed of each wheel corresponding to the target slip ratio Rsti according to the following equation (2). Vwti is calculated, and a target slip ratio Spti of each wheel for achieving the target wheel speed Vwti is calculated according to the following equation 3.
Vwti = Vb (1-Rsti) (2)
Spti = (Vwi−Vwti) / Vwti (3)
[0042]
It should be noted that the wheel speed of the turning inner front wheel may be substituted for the vehicle body speed Vb in the above formula 2. Further, the target slip ratio Spti may be calculated according to the following equation 4 with Ks as a positive coefficient and Vwdi (i = fr, fl, rr, rl) as the rate of change of the wheel speed Vwi.
Spti = {Vwi−Vwti + Ks (Vwdi−Gx)} / Vwti (4)
[0043]
In step 100, it is determined whether there is a possibility that the stability of the vehicle is lowered due to the increase or decrease of the braking force by the motion control. If a negative determination is made, the target is determined in step 110. Based on the slip rate Rsti, the map corresponding to the graph shown by the solid line in FIG. 6 indicates the increasing / decreasing gradient of the braking force of each wheel, that is, the duty ratio Dri (i = fr, fl, rr, rl) is calculated and an affirmative determination is made, the duty of the pressure increasing / decreasing control valve of each wheel is determined based on the target slip ratio Rsti in step 120 and the map corresponding to the graph shown by the broken line in FIG. The ratio Dri is calculated.
[0044]
Note that whether or not there is a possibility that the stability of the vehicle may decrease due to an increase or decrease in braking force due to the motion control is a determination as to whether or not there is a roll suppression control amount B, that is, during roll suppression control. Or the same determination as that in Steps 58 and 60 of the target braking force Fbri calculation routine of the roll suppression control described later, that is, whether the roll amount of the vehicle body is excessive. This determination may be performed.
[0045]
In step 130, the control valve for each wheel is controlled based on the duty ratio Dri calculated in step 110 or 120 so that the braking force of each wheel becomes the target braking force Fbti. Thereafter, the process returns to step 10.
[0046]
In step 22 of the behavioral control target braking force Fbsi calculation routine shown in FIG. 3, the vehicle speed V is calculated based on the wheel speed Vwi, and the lateral acceleration Gy is multiplied by the product γV of the vehicle speed V and the yaw rate γ. The deviation of the lateral acceleration, that is, the lateral slip acceleration Vyd of the vehicle is calculated as the deviation Gy−γV, and the lateral slip acceleration Vyd is calculated by integrating the lateral slip acceleration Vyd. The slip angle β of the vehicle body is calculated as the ratio Vy / Vx of the side slip velocity Vy of the vehicle body.
[0047]
In step 24, the spin amount SV is calculated as a linear sum K1β + K2Vyd of the slip angle β of the vehicle body and the lateral slip acceleration Vyd, with K1 and K2 being positive constants, respectively. The turning direction is determined, and the spin state amount SS is calculated as SV when the vehicle is turning left, and -SV when the vehicle is turning right, and the spin state amount is 0 when the calculation result is a negative value. The spin amount SV may be calculated as a linear sum of the vehicle body slip angle β and its differential value βd.
[0048]
In step 28, the actual steering angle δ of the front wheels is calculated based on the steering angle θ, the target yaw rate γe is calculated according to the following equation 5 with H as the wheel base and Kh as the stability factor, and T is the time constant. Assuming that s is a Laplace operator, an estimated yaw rate γt of the vehicle based on the vehicle speed V and the steering angle θ is calculated according to the following equation (6). The target yaw rate γe may be calculated in consideration of the lateral acceleration Gy of the vehicle so as to take into account the dynamic yaw rate.
γe = Vδ / (1 + KhV²) H ...... (5)
γt = γe / (1 + Ts) (6)
[0049]
In step 30, the drift value DV is calculated according to the following equation (7). The drift value DV may be calculated according to the following formula 8.
DV = (γt−γ) (7)
DV = H (γt−γ) / V (8)
[0050]
In step 32, the turning direction of the vehicle is determined based on the sign of the yaw rate γ, and the drift-out state quantity DS is calculated as DV when the vehicle turns left, and −DV when the vehicle turns right, and the calculation result is negative. When the value is, the drift-out state quantity is zero.
[0051]
In step 34, the target braking force Fssfo of the front wheel outside the turn is calculated from the map corresponding to the graph shown in FIG. 7 based on the spin state quantity SS. In step 36, the target braking force Fssfo is calculated based on the drift-out state quantity DS. The target braking force Fsall of the entire vehicle is calculated from the map corresponding to the graph shown in FIG.
[0052]
In step 38, Ksri is set as the distribution ratio (generally a positive constant larger than 50) of the turning inner rear wheel, and the turning outer front wheel, the turning inner front wheel, the turning outer rear wheel, and the turning inner rear rear according to the following formula 9. Wheel target braking forces Fsfo, Fsfi, Fsro, Fsri are calculated.
Fsfo = Fssfo
Fsfi = 0
Fsro = (Fsall-Fssfo) (100-Ksri) / 100
Fsri = (Fsall−Fssfo) Ksri / 100 (9)
[0053]
In step 40, the turning direction of the vehicle is determined based on the sign of the yaw rate γ to identify the turning inner and outer wheels, and the target braking force Fbsi (i = fr, fl) for behavior control of each wheel based on the identification result. , Rr, rl) are calculated. That is, the target braking force Fbsi is obtained according to the following equations 10 and 11 for the case of the vehicle turning left and turning right, respectively.
[0054]
Fbsfr = Fsfo
Fbsfl = Fsfi
Fbsrr = Fsro
Fbsrl = Fsri (10)
Fbsfr = Fsfi
Fbsfl = Fsfo
Fbsrr = Fsri
Fbsrl = Fsro (11)
[0055]
In step 52 of the target braking force Fbri calculation routine of the roll suppression control shown in FIG. 4, Rrf is the previous value of the estimated roll angular velocity Rr, ωo is the natural frequency of the vehicle body, and φo is the unit gravity acceleration. The roll angular velocity estimated value Rr is calculated according to the following equation 12 with the normal roll angle per hit, ξ as the roll damping coefficient, and ΔT as the cycle time of the flowchart shown in FIG.
Rr = Rrf + {(ωo²(Gyφo−R) −2ωoξRrf} ΔT (12)
[0056]
In step 54, the roll angle estimated value R is calculated according to the following equation 13 using Rf as the previous value of the roll angle estimated value R.
R = Rf + RrΔT (13)
[0057]
In step 56, the roll evaluation value RV is calculated based on the lateral acceleration Gy of the vehicle according to the following equation 14 with Gylim as the allowable limit value of lateral acceleration and Rrlim as the allowable limit value of roll angular velocity. The allowable limit values Gylim and Rrlim may be positive constants, but may be variably set based on the vehicle speed V, for example.
RV = Gy / Gylim + Rr / Rrlim (14)
[0058]
In step 58, it is determined whether or not the absolute value of the lateral acceleration Gy of the vehicle exceeds the reference value Gyo (positive constant). If a negative determination is made, the process proceeds to step 62, where an affirmative determination is made. If so, go to Step 60.
[0059]
In step 60, it is determined whether or not the absolute value of the yaw rate γ of the vehicle exceeds the reference value γo (positive constant). If a negative determination is made, in step 62, the roll suppression control is performed. After the target braking force Fbri is set to 0, the routine proceeds to step 70. When an affirmative determination is made, the routine proceeds to step 64.
[0060]
As understood from the above description, in steps 58 and 60, it is determined whether or not the roll suppression control should be executed by determining whether or not the vehicle is in a situation where the roll amount of the vehicle body is excessive. In step 60, it may be determined whether or not the product of the vehicle yaw rate γ and the vehicle speed V, that is, the estimated lateral acceleration of the vehicle exceeds a reference value (a positive constant).
[0061]
In step 64, the roll suppression control amount B is calculated from the map corresponding to the graph shown in FIG. 9 based on the absolute value of the roll evaluation value RV. In step 66, the roll evaluation value RV or the side of the vehicle body is calculated. The turning direction of the vehicle is determined based on the sign of the acceleration Gy, and Kfout, Krin, and Krout are set to positive constant coefficients, respectively, and when the vehicle is in the left turn state, the target braking force Fbri of the roll suppression control of each wheel is The calculation is performed according to the following Expression 15, and when the vehicle is in a right turn state, the target braking force Fbri of the roll suppression control of each wheel is calculated according to the following Expression 16.
[0062]
Fbrfr = KfoutB
Fbrfl = 0
Fbrrr = KroutB
Fbrrl = KrinB ...... (15)
Fbrfr = 0
Fbrfl = KfoutB
Fbrrr = KrinB
Fbrrl = KroutB (16)
[0063]
Thus, according to the illustrated embodiment, the spin state quantity SS indicating the degree of vehicle spin is calculated in steps 22-26, and the drift-out state quantity indicating the degree of vehicle drift-out in steps 28-32. DS is calculated, and in step 34, the target braking force Fssfo of the outer front wheel for suppressing spin is calculated based on the spin state amount SS, and in step 36, drift out is suppressed based on the drift-out state amount DS. The target braking force Fsall of the entire vehicle for the vehicle is calculated, and in steps 38 and 40, the target braking force Fssfo for suppressing the spin and the target braking force Fsall for suppressing the drift-out are determined for each wheel of the behavior control. The braking force Fbsi is calculated.
[0064]
In steps 52 to 56, a roll evaluation value RV indicating the degree and direction of the roll of the vehicle body is calculated. In steps 58 and 60, the absolute value of the lateral acceleration Gy of the vehicle and the absolute value of the yaw rate γ of the vehicle are calculated. Based on the absolute value of the roll evaluation value RV in step 64, it is determined whether or not roll suppression control should be performed. In step 66, the target braking force Fbri of each wheel for roll suppression control is calculated based on the roll suppression control amount B.
[0065]
In step 70, the target braking force Fbti of each wheel is calculated as the larger value of the target braking force Fbsi for behavior control and the target braking force Fbri for roll suppression control. In step 80, based on the target braking force Fbti. The target slip ratio Rsti of each wheel is calculated, and in step 90, the target wheel speed Vwti of each wheel corresponding to the target slip ratio Rsti is calculated, and the target slip of each wheel for achieving the target wheel speed Vwti. The ratio Spti is calculated, and in step 110 or 120, the increasing / decreasing gradient of each wheel braking pressure, that is, the duty ratio Dri of the increasing / decreasing control valve of each wheel is calculated based on the target slip ratio Spti. By controlling the wheel pressure increase / decrease control valve based on the duty ratio Dri, the braking force of each wheel is controlled to become the target braking force Fbti.
[0066]
For example, when the vehicle is in a spinning state, braking force is applied to the front wheels on the outside of the turn and a yaw moment in the spin suppression direction is applied to the vehicle, so that spin is suppressed, and when the vehicle is in a drift-out state, A braking force is applied, the vehicle is decelerated, and a yaw moment in the turning assist direction is applied to the vehicle, thereby suppressing drift-out. Also, when the roll of the vehicle body is excessive, braking force is applied to the front outer wheel and the left and right rear wheels, the vehicle is decelerated and the turning radius of the vehicle is increased, thereby reducing the centrifugal force acting on the vehicle. This suppresses the roll of the vehicle body.
[0067]
In particular, according to the illustrated embodiment, in step 100, it is determined whether or not there is a possibility that the stability of the vehicle may decrease due to an increase or decrease in the braking force due to the vehicle motion control. If this is done, that is, if there is a risk of a decrease in the stability of the vehicle, in step 120, the duty ratio Dri of the increasing / decreasing control valve of each wheel corresponds to the graph shown by the broken line in FIG. Since the pressure reduction gradient of the braking pressure is reduced as compared with the normal time by the map, the roll control or the behavior control and the roll suppression control executed especially when the roll amount of the vehicle body is excessive. By being executed simultaneously, the braking force of the wheels is rapidly reduced, and thereby it is possible to reliably prevent the stability of the vehicle from being lowered due to the pitching of the vehicle due to a sudden load movement.
[0068]
Further, according to the illustrated embodiment, when there is a possibility that the stability of the vehicle is lowered due to an increase or decrease in the braking force due to the vehicle motion control, the pressure reduction gradient of the braking pressure is only reduced compared to the normal time. In addition, the braking pressure increase gradient is reduced to some extent compared to the normal time, so that the braking pressure is increased rapidly by the roll suppression control without sacrificing the effect of the roll suppression control. It is possible to reliably prevent the stability of the vehicle from being lowered due to pitching or the like.
[0069]
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.
[0070]
For example, in the illustrated embodiment, whether or not there is a possibility of pitching of the vehicle executed in step 100 is determined whether there is a roll suppression control amount B or roll suppression control. The same determination as in steps 58 and 60 of the target braking force Fbri calculation routine is performed, but it is determined whether or not the absolute value of the longitudinal acceleration Gx exceeds the reference value, that is, the actual vehicle It may be performed by determining the degree of pitching.
[0071]
Further, in the illustrated embodiment, when it is determined that there is a possibility that the stability of the vehicle may be lowered, in step 120, the braking pressure increasing gradient is also reduced to some extent. However, the possibility that the stability of the vehicle will decrease due to a sudden increase in braking pressure is greater than the possibility that the stability of the vehicle will decrease due to a sudden decrease in braking pressure. Since it is low, the reduction of the braking pressure increase gradient in step 120 may be omitted.
[0072]
In the illustrated embodiment, when the increasing / decreasing gradient of the braking pressure is reduced, the duty ratio Dri of the increasing / decreasing control valve of each wheel is constant when the target slip ratio Spti exceeds the reference value. The value is maintained at a value, but as indicated by the alternate long and short dash line in FIG. 6, the target slip rate Spti becomes smaller than the normal value as the size of the target slip rate Spti becomes larger than the reference value. The duty ratio Dri may be corrected so as to gradually increase.
[0073]
In the illustrated embodiment, the spin state quantity SS and the drift-out state quantity DS are calculated, and the behavior control target braking force Fbsi is calculated based on the spin state quantity SS and the drift-out state quantity DS. However, only one of the spin state quantity SS and the drift-out state quantity DS may be calculated, and the behavior control target braking force Fbsi may be calculated based on the spin state quantity SS or the drift-out state quantity DS. In addition, the target braking force based on the drift-out state quantity DS is calculated for the left and right rear wheels, but it is calculated for the three wheels excluding the turning outer front wheel or only for the turning inner rear wheel. May be.
[0074]
In the illustrated embodiment, the target braking force for the roll suppression control is calculated for the three wheels except the turning inner front wheel, but the target braking force for the roll suppression control is calculated only for the turning outer front wheel. It may be modified so that.
[0075]
【The invention's effect】
  As is apparent from the above description, the first aspect of the present invention is as follows.And 2With this configuration, the acceleration / deceleration of the vehicle during motion control isat leastRapidlyDecreaseTo avoid braking force due to motion control.Sudden decreaseIt is possible to reliably prevent the vehicle stability from being lowered due to the above, and to stabilize the movement of the vehicle effectively and reliably.
[0076]
  And claims1 andAccording to the configuration of 2, not only when there is a possibility that the stability of the vehicle is lowered due to increase or decrease of the braking force due to the roll suppression control, but also when the behavior control and the roll suppression control are executed simultaneously, Even when there is a possibility that the stability of the vehicle is lowered due to the increase / decrease of the braking force, the braking force changing speed can be surely lowered.
[0077]
  In particularClaim1According to the configuration, it is possible to reliably prevent the stability of the vehicle from being lowered due to the increase or decrease of the braking force by the roll suppression control.2According to this configuration, it is possible to reliably prevent the stability of the vehicle from being lowered due to increase / decrease in braking force due to motion control in a situation where the roll of the vehicle body is large.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing one preferred embodiment of a vehicle motion control apparatus according to the present invention.
FIG. 2 is a flowchart showing a main routine of motion control in the illustrated embodiment.
FIG. 3 is a flowchart showing a target braking force Fbsi calculation routine for behavior control in step 20 of the flowchart shown in FIG. 2;
FIG. 4 is a flowchart showing a target braking force Fbri calculation routine for roll suppression control in step 50 of the flowchart shown in FIG. 2;
FIG. 5 is a graph showing a relationship between a target braking force Fbti of each wheel and a target slip ratio Rsti of each wheel.
FIG. 6 is a graph showing the relationship between the target slip ratio Spti of each wheel and the duty ratio Dri of the pressure increasing / decreasing control valve of each wheel.
FIG. 7 is a graph showing a relationship between a spin state amount SS and a target braking force Fssfo of a turning outer front wheel.
FIG. 8 is a graph showing a relationship between a drift-out state quantity DS and a target braking force Fsall of the entire vehicle.
9 is a graph showing a relationship between a roll evaluation value RV and a roll suppression control amount B. FIG.
[Explanation of symbols]
10FR ~ 10RL ... wheel
20 ... braking device
28 ... Master cylinder
30 ... Electric control device
32FR ~ 32RL ... Wheel speed sensor
34 …… Steering angle sensor
36 ... Yaw rate sensor
38. Longitudinal acceleration sensor
40 ... Lateral acceleration sensor

Claims (4)

A vehicle motion control device that performs a motion control that stabilizes the motion of the vehicle by applying a braking force to the wheel based on the running state of the vehicle, a behavior control means that stabilizes the turning behavior of the vehicle, Roll suppression control means for suppressing rolls, and means for calculating a final target control amount for each wheel based on a target control amount for each wheel by the behavior control means and a target control amount for each wheel by the roll suppression control means And means for controlling motion by controlling the braking force of each wheel based on the final target control amount, and there is a risk that the stability of the vehicle may be reduced due to increase or decrease in braking force due to the motion control. a determination unit, have a means for reducing the at least reduce the rate of the braking force due to the motion control when the risk of reduction of the vehicle stability is determined by the determining means, said determining means the b Vehicle motion control device, characterized in that the stability of the vehicle is determined that there is a possibility to decrease when the roll control by Le suppression control means is executed. A vehicle motion control device that performs a motion control that stabilizes the motion of the vehicle by applying a braking force to the wheel based on the running state of the vehicle, a behavior control means that stabilizes the turning behavior of the vehicle, Roll suppression control means for suppressing rolls, and means for calculating a final target control amount for each wheel based on a target control amount for each wheel by the behavior control means and a target control amount for each wheel by the roll suppression control means And means for controlling motion by controlling the braking force of each wheel based on the final target control amount, and there is a risk that the stability of the vehicle may be reduced due to increase or decrease in braking force due to the motion control. a determination unit, wherein when the risk of reduction of the vehicle stability is determined by the determining means to have a means for reducing the at least reduce the rate of the braking force due to the motion control, the determination unit vehicle Vehicle motion control device, characterized in that the stability of the vehicle is determined that there is a possibility to decrease when the state quantity of magnitude indicating the degree of Lumpur exceeds the reference value. The vehicle motion control device according to claim 1 or 2, wherein the means for reducing at least the rate of decrease in braking force by the motion control reduces only the rate of decrease in braking force by the motion control. The means for calculating the final target control amount of each wheel calculates the larger value of the target control amount by the behavior control means and the target control amount by the roll suppression control means as the final target control amount for each wheel. The vehicle motion control device according to claim 1, wherein the vehicle motion control device is provided.

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