JP4535178B2 - Vehicle behavior control device - Google Patents

Description

  The present invention relates to a vehicle behavior control device that stabilizes the behavior of a vehicle such as an automobile during travel, and more specifically, a control amount given using a vehicle body slip angle, its differential value, and its second-order differential value. The present invention relates to an apparatus for controlling a behavior so as to suppress a vehicle's spin behavior (side slip behavior).

  In the field of motion control of vehicles such as automobiles, VSC (Vehicle Stability Control) which improves the stability of the behavior of the vehicle in the yaw direction during turning by electronically controlling the operation of the braking / driving system or the steering system Many behavior control technologies such as VDIM (Vehicle Dynamic Integrated Management) have already been proposed (for example, Patent Documents 1 and 2). In a typical VSC, if there is a possibility that the behavior of the vehicle becomes unstable, the tire slip rate or slip amount (hereinafter referred to as “slip rate”) or the wheel steering angle of each wheel. Adjustments are made, or engine or motor power is reduced or limited to limit vehicle acceleration. As is well known, when a braking / driving force difference is generated between the left and right wheels of a vehicle or a wheel rudder angle is adjusted, a yaw moment is generated around the center of gravity of the vehicle, thereby changing the turning direction of the vehicle. Further, when the vehicle speed is reduced, the lateral force required for turning is reduced. Therefore, by adjusting the slip ratio of each wheel or the wheel rudder angle and limiting or decelerating the acceleration of the vehicle, the spin of the vehicle is reduced. Such an unstable behavior of the vehicle is suppressed, and the behavior of the vehicle in the yaw direction is stabilized.

In the behavior control as described above, more specifically, a turning state amount representing a turning state of the vehicle, for example, a spin state amount or a skid state amount which is a function of a vehicle body slip angle, an oversteer state amount, an understeer state. The quantity is referred to as an index value of the behavior of the vehicle, and when these index values deviate from the values assumed in the vehicle that is stably running, or when a predetermined threshold value is exceeded, Behavior stabilization control, that is, generation of a yaw moment that stabilizes the behavior (behavior stabilization yaw moment) or limitation or deceleration of acceleration of the vehicle is executed. However, after the turning state amount representing the vehicle behavior exceeds a threshold value or a predetermined range, adjustment of the slip ratio of each wheel for controlling the behavior stabilization (wheel slip control), automatic control or braking / driving of the wheel steering angle There may be a time delay before the control of the device is started. Therefore, in such control, in order to speed up the control responsiveness and to suppress the tendency of vehicle behavior instability more quickly, the turning state quantity or a partial differential value thereof is more It may be added to the index value (see, for example, Patent Document 1). Since the differential value of the amount representing the vehicle behavior is a primary advance amount of the amount representing the vehicle behavior, the time delay described above can be obtained by adding such a differential value to the index value for executing the behavior stabilization control. Can be compensated.
JP 2004-306662 A JP 2005-206075 A

Among the vehicle behavior controls as described above, in particular, in the control for suppressing the spin of the vehicle (spin suppression control), the vehicle slip is typically used as an index value of the vehicle behavior, that is, a control amount. Spin state quantity which is a linear sum of an angle and its differential value K1 · β + K2 · dβ / dt (A)
Is referred to (Patent Document 2). Here, K1 and K2 are weighting factors. The amount of spin state is an amount corresponding to the yaw moment necessary to return the vehicle body slip angle to zero. However, when behavior stabilization control is started with reference to only such an amount, there is a possibility that a time delay will occur as already mentioned. Therefore, in the spin suppression control, a linear sum obtained by adding the ^second derivative d ² β / dt ² of the vehicle body slip angle to the above-described spin state quantity,
K1 · β + K2 · dβ / dt + K3 · d ² β / dt ² (B)
May be used to execute behavior stabilization control (K3 is a predetermined coefficient). When controlling using such a linear sum, the behavior stabilization control is started at the stage when a sign of the occurrence of spin occurs in the vehicle, so that the possibility of the vehicle falling into a spin state can be avoided more reliably. It becomes.

However, in the study by the inventors of the present invention, as described above the linear sum (B), executes the behavior stabilization control by using the control amount including the second order differential value d ² beta / dt ² of the vehicle body slip angle In this case, it has been found that when the sudden steering is repeated, the action of the behavior stabilization control is reduced at an early stage, and a phenomenon in which the spin suppression effect is impaired can occur. Such a phenomenon occurs when the response of the second-order differential value d ² β / dt ² of the vehicle body slip angle is fast, and when the control effect starts to appear after the behavior stabilization control is started, the vehicle body slip angle of 2 It became clear that the second order differential value is due to catching the sign. That is, in order to avoid the reduction of the spin suppression effect, it is necessary to appropriately adjust the contribution of the second-order differential value of the vehicle body slip angle in the control amount according to the steering condition.

  Thus, one object of the present invention is to perform behavior stabilization control so as to suppress the vehicle's spin behavior using the amount calculated based on the vehicle body slip angle, its differential value, and its second-order differential value as a control amount. The present invention provides a control device that is configured to prevent the spin suppression effect from being impaired due to the contribution of the second-order differential value of the vehicle body slip angle under a specific steering condition.

  Another object of the present invention is to provide an apparatus as described above, which is configured such that the contribution of the second-order differential value of the vehicle body slip angle is reduced when the sudden steering is repeated. is there.

  According to the present invention, the above-described problem is solved by the vehicle that suppresses the spin of the vehicle based on the control amount calculated from the vehicle body slip angle, the differential value of the vehicle body slip angle, and the second-order differential value of the vehicle body slip angle. The behavior control device, wherein the steering is executed in one of the left and right directions of the vehicle, and the one of the ones within a predetermined period after the magnitude of the second-order differential value of the vehicle body slip angle exceeds a predetermined value When the steering is executed in the direction opposite to the direction of the vehicle and the magnitude of the second derivative of the vehicle body slip angle exceeds a predetermined value, the contribution of the second derivative of the vehicle body slip angle to the control amount is reduced. This is achieved by a device characterized in that. The vehicle behavior control device is of a type that suppresses the spin of the vehicle by generating a yaw moment that suppresses the spin based on the control amount or by limiting the acceleration of the vehicle. It may be.

  In the above configuration, “in the predetermined period after the steering is executed in one of the left and right directions of the vehicle and the magnitude of the second-order differential value of the vehicle body slip angle exceeds the predetermined value” When steering is performed in the direction opposite to one direction and the magnitude of the second derivative of the vehicle body slip angle exceeds a predetermined value, the sudden steering is performed twice from right to left or from left to right. This corresponds to a case where the process is repeated (the “predetermined period” may be an arbitrarily set period of, for example, about 2 to several seconds). As understood by those skilled in the art, when sudden steering is performed during normal vehicle travel, the size of the slip angle of the vehicle body increases rapidly. Because it changes before the vehicle body slip angle and its differential value, sudden steering is detected by detecting that the second-order differential value of the vehicle body slip angle fluctuated greatly within a short period (predetermined period). It will be possible.

  Thus, according to the configuration of the device of the present invention, the vehicle spin is suppressed based on the control amount calculated from the vehicle body slip angle, the differential value of the vehicle body slip angle, and the second-order differential value of the vehicle body slip angle. When the behavior control of the vehicle to be executed is executed, if the sudden steering is repeated twice in different directions, the contribution of the second-order differential value of the vehicle body slip angle is reduced. In general, when the spin suppression control is executed based on the control amount including the second-order differential value of the vehicle body slip angle, even if there is a sudden steering, the second-order differential value of the vehicle body slip angle responds to the rapid steering. Thus, the spin suppression effect is exhibited, and the slip angle or yaw rate of the vehicle body of the vehicle is quickly converged. However, when the sudden steering is executed twice in a short time, before the slip angle or the yaw rate converges during the second steering, the second-order differential value of the vehicle body slip angle is early corresponding to the tendency. As a result, the action of the spin suppression control generated based on the control amount may be reduced (see the description of the embodiment for a specific example). Therefore, in the apparatus of the present invention, as described above, when the sudden steering is executed twice, the contribution of the second-order differential value of the vehicle body slip angle is reduced thereafter, and the effect of the spin suppression control is reduced. An attempt is made to avoid the reduction.

  Note that “the one direction is within a predetermined period after steering is executed in one of the left and right directions of the vehicle and the magnitude of the second-order differential value of the vehicle body slip angle exceeds a predetermined value. When the steering is executed in the opposite direction and the magnitude of the second-order differential value of the vehicle body slip angle exceeds a predetermined value, that is, when the sudden steering is executed twice in different directions, the control amount is In the case of reducing the contribution of the second derivative of the vehicle body slip angle, the contribution of the second derivative of the vehicle body slip angle is ignored, and the slip angle of the vehicle body and its derivative (slip angle changing speed) Can be quickly converged.

  Also, the contribution of the second derivative of the vehicle body slip angle in the controlled variable reduces the action of the spin suppression control because the second derivative of the vehicle body slip angle gives an early indication of the effect of the action of the spin inhibition control. Therefore, since the second-order differential value of the vehicle body slip angle is reduced, the second-order differential value of the vehicle body slip angle is reduced after the two rapid steering operations. Is reversed, that is, when the magnitude of the second derivative of the vehicle body slip angle becomes smaller than a second predetermined value (a value smaller than the first predetermined value). It may be.

  Furthermore, as will be understood from the following description (see the “Embodiment” column), the contribution of the second-order differential value of the vehicle body slip angle hinders the effect of the spin suppression control. It is understood that the positive / negative sign of the floor differential value is opposite to the positive / negative signs of both the vehicle body slip angle and the vehicle body slip angle differential value. Therefore, as a mode of control in the above apparatus, the contribution of the second-order differential value of the vehicle body slip angle is reduced because the sign of the second-order differential value of the vehicle body slip angle is the differential value of the vehicle body slip angle and the vehicle body slip angle. It may be done when the signs of both are reversed.

  Thus, after executing the reduction of the contribution of the second-order differential value of the vehicle body slip angle after the two sudden steering operations described above, when the vehicle body slip angle and the slip angular velocity settle down, the vehicle body slip angle is prepared for the next steering operation. It is preferable that the effect of the second-order differential value can be used. Therefore, in the above apparatus, the reduction of the contribution of the second derivative of the vehicle body slip angle in the control amount may be canceled after the predetermined period has elapsed.

In the embodiment, the controlled variable includes the vehicle body slip angle β, the vehicle body slip angle differential value dβ / dt, the vehicle body slip angle second-order differential value d ² β / dt ² , and predetermined coefficients K1, K2. , Using K3,
K1 · β + K2 · dβ / dt + K3 · d ² β / dt ²
May be given by In this case, when the control amount increases, a yaw moment that suppresses spin is generated, or the acceleration of the vehicle is limited, thereby suppressing the spin. Reduction of the contribution of the second-order differential value of the vehicle body slip angle in the control amount may be performed by setting the value of the coefficient K3 to zero.

  Thus, generally speaking, in the configuration of the apparatus of the present invention, in the vehicle spin suppression control, the contribution of the second derivative value of the vehicle body slip angle for speeding up the operation effect of the control depends on the vehicle steering conditions. By adjusting appropriately, when the contribution of the second-order differential value of the vehicle body slip angle is unnecessary, it can be said that the action is excluded. According to the configuration of the present invention, since the contribution of the second-order differential value of the vehicle body slip angle is effective at the time when the sudden steering is started, the vehicle body slip angle and the differential value can be quickly brought to convergence. On the other hand, it becomes possible to prevent the control action from terminating early when the control effect starts to appear. In other words, the configuration of the present invention can be used only when the contribution of the second-order differential value of the vehicle body slip angle in the control amount is valid, and is more effective in suppressing the spin than before. There is expected.

  Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention.

Vehicle Configuration FIG. 1A schematically shows an automobile in which a preferred embodiment of the behavior control device of the present invention is incorporated. In the figure, the vehicle 10 having the left and right front wheels 12FL and 12FR and the left and right rear wheels 12RL and 12RR is arranged in a normal manner according to the depression of the accelerator pedal by the driver (in the illustrated example, Since it is a rear wheel drive vehicle, a drive system device (only part of which is shown) that generates braking / driving force on the rear wheels, and a steering device 30 for controlling the steering angle of the front wheels (further, steering for the rear wheels) And a braking system device 40 that generates a braking force on each wheel. The drive system is configured so that the drive torque or the rotational force is transmitted from the engine and / or the electric motor (not shown) to the rear wheel 12RL via the transmission (not shown), the differential gear device 28, etc. , 12RR. The vehicle may be a front-wheel drive vehicle or a four-wheel drive vehicle, and in that case, the rotational force of the drive train device is transmitted to the front wheels or all the wheels. Further, the steering device transmits the rotation of the steering wheel 32 operated by the driver to the tie rods 36L and 36R while boosting the rotational force by the booster 34, and steers the front wheels 12FL and 10FR. It may be.

  The braking system device 40 includes a wheel cylinder 42i (i = FL, FR, RL) mounted on each wheel by a hydraulic circuit 46 that communicates with a master cylinder 45 that is operated in response to the driver depressing the brake pedal 44. , RR, and so forth.) Is an electronically controlled hydraulic brake device in which the brake pressure in the wheel, that is, the braking force in each wheel, is adjusted. In the hydraulic circuit 46, various valves (master cylinder cut valve, hydraulic pressure holding valve) for selectively communicating the wheel cylinder of each wheel to a master cylinder, an oil pump or an oil reservoir (not shown) in a normal manner. In a normal operation, the pressure of the master cylinder 45 is supplied to each wheel cylinder 42i in response to the depression of the brake pedal 44. However, in the case where the braking force of each wheel is adjusted individually or independently in order to execute the behavior control according to the present invention or any other braking force distribution control, based on the command of the electronic control unit 50, Various valves are operated, and the brake pressure in the wheel cylinder of each wheel is controlled to match each target pressure based on the detection value of the corresponding pressure sensor. The braking system device 40 may be of a type that applies a braking force to each wheel pneumatically or electromagnetically, or any other type for those skilled in the art.

  The behavior control and the operation control of the braking system device 40 of the present invention are executed by the electronic control device 50 as already mentioned. The electronic control unit 50 may include a microcomputer having a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other by a bidirectional common bus, and a driving circuit. In the figure, the electronic control unit 50 receives the brake pedal depression amount θb, the steering angle δ, the wheel speed Vwi, the pressure Pbi in the wheel cylinder of each wheel, and the lateral acceleration Gy from sensors provided in each part of the vehicle. The detection value such as the yaw rate γ is illustrated as being input. However, various parameters necessary for various controls to be executed in the vehicle of the present embodiment, for example, various detection signals such as the front and rear G sensor values. May be entered.

Configuration and Operation of Electronic Control Device FIG. 1B shows an electronic control device 50 that realizes the behavior control device of the present invention in the form of a control block. It should be understood that the configuration and operation of the illustrated control device are realized by processing operations of the CPU or the like in the electronic control device 50 during operation of the vehicle.

  With reference to the figure, the control device 50 for executing the behavior control of the present embodiment may be similar to any known type of VSC or VDIM device in its basic configuration. Generally speaking, the control device 50 calculates a turning state amount (turning state index value) representing the behavior of the vehicle during turning, and based on the turning state amount, the target slip ratio Si of each wheel and the drive of the drive device. A hydraulic circuit for controlling the brake pressure of each wheel by referring to the VSC unit 50a for determining the torque down rate Td for reducing the output, the brake pedal depression amount θb from the brake pedal sensor 44, and the target slip rate Si for each wheel. And a drive control device 50c for controlling the engine torque with reference to the accelerator opening θa and the torque down rate Td from the accelerator opening sensor 16.

In such a configuration, first, the VSC unit 50a calculates the spin state amount SP by the following equation as a turning state amount (turning state index value) representing the behavior of the vehicle during turning. :
SP = K1 · β + K2 · dβ / dt + K3 · d 2 β / dt 2 ... (1)
Here, β, dβ / dt, and d ² β / dt ² are the vehicle body slip angle, the differential value of the vehicle body slip angle, and the second order differential value of the vehicle body slip angle, respectively, and K1, K2, and K3 are experimental values. Is a weighting factor determined by (usually a constant). The amount of spin state is an index value of the spin state or side slip amount of the vehicle that is turning. Generally speaking, the sum of the first term and the second term is necessary to return the vehicle body slip angle to 0 (stable The term corresponding to the magnitude of the yaw moment and the second-order differential value (third term) of the vehicle body slip angle are further added to speed up the control response.

In the above equation (1), the differential value dβ / dt of the vehicle body slip angle is obtained by using the lateral acceleration Gy, the vehicle speed Vx, and the yaw rate γ.
dβ / dt = Gy / Vx−γ (2a)
Given by. The vehicle speed Vx may typically be determined by the vehicle speed determination unit 50d in any known manner from the wheel speed value Vwi of each wheel from the wheel speed sensor, but a vehicle speed sensor is provided. If it is, the detected value may be used. The vehicle body slip angle is obtained by integrating the equation (2a)
β = ∫ (Gy / Vx−γ) dt (2b)
Given by. And the second order differential value of the vehicle body slip angle is obtained by differentiating the equation (2a).
d ² β / dt ² = d (Gy / Vx−γ) / dt (2c)
Given by.

A so-called “dead zone” may be provided for the second-order differential value of the vehicle body slip angle. That is, when the second-order differential value d ² β / dt ² of the vehicle body slip angle is calculated from the differential value dβ / dt of the vehicle body slip angle, the absolute value of the value obtained by differentiating (dβ / dt) is smaller than a predetermined value. Forcibly, the second derivative of the vehicle body slip angle is set to 0 (d ² β / dt ² ← 0). However, in order to avoid that the value of the spin state quantity changes discontinuously, in the calculation of the linear sum of Equation (1), the body slip that takes a value obtained by differentiating (dβ / dt) or 0. A value obtained by applying a first-order regression filter process (smoothing process) to the second-order differential value d ² β / dt ² of the corner is adopted.

  Thus, when the spin state quantity is calculated according to the equation (1), the VSC unit 50a further generates the yaw moment for correcting the turning behavior of the vehicle so that the spin state quantity becomes zero. A target value Si of the slip ratio (tire force) is determined, and the target slip ratio Si is transmitted to the braking control device 50b. In the braking control device 50b, taking into consideration the depression amount of the brake pedal 44, control commands (commands for various valves and pumps in the circuit) are sent to the hydraulic circuit 46 of the braking system device so that the target slip ratio Si of each wheel is achieved. ) And actuate the braking device (wheel cylinder) of each wheel. Typically, when the magnitude of the spin state quantity is greater than a predetermined threshold value greater than 0, the target slip ratio Si of the front wheel outside the turn is selectively increased, thereby turning the vehicle body out of the turn. A yaw moment is generated in the direction in which the vehicle is driven, and thus the spin of the vehicle (slide to the outside of the vehicle at the rear of the vehicle) is suppressed. [Typically, instead of generating a yaw moment sufficient to correct the behavior, when the spin state quantity exceeds a threshold value, an appropriate amount of yaw moment depends on the magnitude of the spin state quantity. Each wheel slip ratio is distributed and controlled in the direction in which the slippage is generated, and the slip ratio is adjusted by feedback control so that each turning state amount settles below a predetermined value. ]

  Further, when the amount of spin state is larger than a predetermined threshold, there is a possibility that the lateral force necessary for turning cannot be generated in the vehicle, or the tire force of the rear wheel has reached the limit. Therefore, the drive output may be limited to limit the speed increase of the vehicle (if the vehicle speed is reduced, the lateral force required for turning is reduced and the vehicle behavior is stabilized). Specifically, first, in the VSC unit 50a, the torque down rate Td that increases as the magnitude of the spin state amount increases is determined and transmitted to the drive control device 50c. The drive control device 50c refers to the torque down rate Td and the driver request torque determined based on the driver's accelerator pedal depression amount (accelerator opening), and the requested drive to be given to the drive device. Torque is determined and converted into a control command for each part of the drive device that realizes the value (the control command is a throttle opening or the like in the case of a gasoline engine) and is given to each part of the drive device. Thus, the drive output of the drive device is limited while the torque state Td is greater than zero.

  In the above behavior control device, in addition to the spin state quantity, in any known format, an index indicating that it has fallen into or may fall into a drift-out state, an understeer state, or an oversteer state. The turning state quantity is calculated together, and the target slip ratio Si and the torque down rate Td are calculated using the turning state quantity as variables, and the brake pressure of each wheel braking device and the drive output of the driving device are adjusted. You may be supposed to. In that case, when it is detected that the vehicle is in an oversteer state or is likely to fall, each wheel brake pressure is controlled in a manner similar to the above-described spin suppression. On the other hand, when it is detected that the vehicle has entered or is likely to fall into a drift-out state or an understeer state, the target slip ratio Si of the front wheels and both rear wheels inside the turn is selectively increased, thereby As the vehicle is decelerated, a yaw moment that turns the vehicle body inward is generated. When it is detected that the behavior of the vehicle is unstable as described above, in any case, the drive output may be limited in a manner similar to spin suppression. .

Correction in Calculation of Spin State Quantity As described above, the VSC unit 50a calculates the spin state quantity and adjusts or drives the slip ratio (ie, braking force) of each wheel so that these values converge to zero. Output restriction is performed. In such control, according to the research of the inventors of the present invention, as described in the “Disclosure of the Invention” section, the vehicle turns to the left after the right turn or turns to the left. If sudden steering is repeated twice in different directions to the right turn after the turn, the amount of spin state is reduced early, before the vehicle body slip angle or yaw rate converges, which is given to each wheel A phenomenon has been found in which the braking force for suppressing spin that should be reduced is quickly reduced. FIG. 2 shows that when the sudden steering is performed twice in different directions as described above (when the steering angle is changed to the left after being changed to the right), the spin state quantity becomes early. That is, in the case where a phenomenon in which the yaw rate is reduced before convergence is observed, the steering angle (a), the spin state amount and each term (b) constituting the steering angle (a), the left wheel control amount (left front wheel braking force) (c ), The measured data of the right wheel control amount (right front wheel braking force) (d) and yaw rate (e) are shown (in the figure, the steering angle and yaw rate are defined with the left turning direction defined as positive, The vehicle body slip angle is defined by the angle in the direction of the speed vector as viewed from the longitudinal axis of the vehicle, so the vehicle body slip angle changes in the + direction when the vehicle turns right.

Referring to FIG. 2, first, as shown in FIG. 2 (a), when the steering angle is suddenly changed to the right, first, as understood by those skilled in the art, first, the spin state quantity SP. The term of the second derivative of the vehicle body slip angle (K3 · d ² β / dt ² : solid thin line) first increases, and then the term of the derivative of the vehicle body slip angle (K2 · dβ / dt: one-dot chain line) and the vehicle slip angle term (K1 · β: broken line) increase in order (FIG. 2B). Here, since the response of the second-order differential value of the vehicle body slip angle is quick, the spin state amount SP (solid bold line) substantially follows the change in the steering angle in the figure, as shown in the figure. In this case, the left wheel control amount is generally raised upward, as illustrated in FIG. 2C.

  Then, after the above right turn, when the direction is changed and the left turn is made, this time, the term of the second derivative of the vehicle body slip angle responds quickly to the change, After this, the differential value term of the vehicle body slip angle changes in a convex manner downward, thereby changing the spin state quantity downward, as shown in FIG. As shown, the right wheel control amount is generated. [When the differential value term of the vehicle body slip angle starts to decrease from the upper peak value, there is a period in which the second-order differential value term of the vehicle body slip angle is transiently held at zero. This is because a dead zone is provided for the second-order differential value of the vehicle body slip angle, as already described. The same applies hereinafter. ]

  Thus, when the right wheel control amount, that is, the right front wheel braking force increases, the vehicle is given a yaw moment that turns the vehicle outward (rightward), and the spin begins to be suppressed. However, when the magnitude of the differential value of the vehicle body slip angle starts to decrease (beginning to increase from the lower peak) due to the effect of the right wheel control amount thereafter, the second-order differential value of the vehicle body slip angle The term reacts quickly to the change, and before the terms of the differential value of the vehicle body slip angle and the vehicle body slip angle converge, the term changes again in the figure. Then, as shown in the figure, the magnitude of the spin state amount is temporarily reduced (the region indicated by the white arrow in the figure), and accordingly, the right wheel control amount is also reduced, and the spin suppression effect is inhibited. Then, due to the temporary reduction of the spin suppression effect, the convergence of the yaw rate is delayed as shown in FIG.

  Therefore, in order to avoid a phenomenon in which the spin suppression effect is temporarily reduced and the convergence of the yaw rate is delayed after the sudden steering as described above is executed twice in different directions, the behavior control device of the present invention In the control configuration, after the two rapid steering operations, the calculation process of the spin state quantity is corrected so as to temporarily reduce or ignore the contribution of the second-order differential value of the vehicle body slip angle to the spin state quantity. . In order to achieve such a configuration, in the present embodiment, the second-order differential value term of the vehicle body slip angle is monitored, and the second-order differential value term of the vehicle body slip angle is displayed in different directions within a predetermined period. When deviating from the threshold range, it is determined that the sudden steering was performed twice in different directions (as understood by those skilled in the art, when the vehicle starts turning, the vehicle body slip angle changes). The second-order differential value of the vehicle body slip angle first changes following the change in the steering angle.) Then, after the determination is made, when the sign of the second-order differential value term of the vehicle body slip angle is reversed, the contribution of the second-order differential value term of the vehicle body slip angle in the spin state quantity is subsequently made. Ignored temporarily.

  FIG. 3 shows, in the form of a flowchart, the calculation process of the spin state quantity that achieves the above control configuration. The illustrated process is repeatedly executed at a predetermined processing cycle time by the VSC unit 50a while the vehicle is traveling.

Referring to the figure, the arithmetic processing shown in the figure is roughly composed of the following processing. :
Process (a) [Step 10]-Weight coefficient K1 in the linear sum of the vehicle body slip angle, the differential value of the vehicle body slip angle, and the second order differential value of the vehicle body slip angle represented by the above equation (1), A process of determining K2 and K3 in an arbitrary manner;
Process (b) [Step 20-50]-A process for determining whether or not the vehicle has been steered rightward and, if it is determined that the vehicle has been steered rightward, measures the time from that time;
Process (c) [Step 60-90]-A process for determining whether or not the vehicle has been steered to the left and, if it has been determined that the vehicle has been steered to the left, to measure the time from that time;
Process (d) [Steps 100, 120] —Process for determining whether or not the vehicle has been steered in the opposite direction within a predetermined period of time after the vehicle has been steered right or left;
Process (e) [Steps 130-160]-in the amount of spin state when the vehicle is steered in the opposite direction within a predetermined period of time after the vehicle is steered to the right or left. Processing for detecting when the sign of the second-order differential value K3 · d ² β / dt ² of the vehicle body slip angle is reversed and setting the coefficient K3 to 0 when such sign is reversed;
Process (f) [Step 170]-A process of calculating the spin state quantity using the coefficients K1-K3 given in accordance with the above processes.

  In the processing configuration described above, first, in the processing (a), the weighting coefficient used for the linear sum of the spin state quantities of the equation (1) is usually determined from experimentally obtained data (step 10). .

In the process (b), whether or not the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle in the spin state quantity exceeds a predetermined threshold th1,
K3 · d ² β / dt ² > th1 (3)
It is first determined whether or not is established (step 20). If the expression (3) is satisfied, it is determined that the rightward steering is performed suddenly, and the flag F1 is turned on to store the fact (step 30). Once the flag F1 is set, the count T1 is increased in the processing cycle that is repeated subsequently (steps 40 and 50).

In the above process (c), whether claim K3 · d ² β / dt ² of the second order derivative in the in the vehicle body slip angle to the spin state quantity is below a predetermined threshold value -Th1, that is,
K3 · d ² β / dt ² <−th1 (4)
It is first determined whether or not is established (step 60). If the expression (5) is established, it is determined that the leftward steering is suddenly performed, and the flag F2 is turned on to store the fact (step 70). Once the flag F2 is set, the count T2 is incremented in the subsequent repeated processing cycle (steps 80 and 90).

Thus, in either of the above processes (b) or (c), sudden steering is executed in either one of the left and right directions, and the term K3 · d ² β of the second-order differential value of the vehicle body slip angle. When it is determined that / dt ² exceeds either one of the predetermined threshold ranges th1 to -th1, one of the flags F1 and F2 is turned on, and the corresponding counter T1 or T2 starts counting. The After that, when sudden steering is executed in the other of the left and right directions of the vehicle, the flags F1 and F2 are both turned on.

In the process (d), the process of monitoring whether the value of the counter T1 or T2 has reached Tht1 or Tht2 while the processing cycle is repeated after the count of the counter T1 or T2 is started (step 100). When, whether the flag F1 and F2 are both turned oN, i.e., terms K3 · d ² β / dt ² of the second order derivative of the vehicle body slip angle by quick steering is performed to the right or left After exceeding one side of the predetermined threshold range th1 to -th1, before the counter T1 or T2 reaches the predetermined value Tht1 or Tht2, the sudden steering is further performed in a direction different from the initial sudden steering direction. A process for monitoring whether or not the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle exceeds the other side of the predetermined threshold range th1 to -th1 by being executed (step 120). Are executed. The predetermined periods Tht1 and Tht2 are short periods that can be arbitrarily set, for example, 2 to several seconds (usually, they may be the same length). Therefore, here, it is detected whether or not there is the first sudden steering and the second sudden steering is performed within a short period of time.

  According to the process (d), first, when the sudden steering is not performed in any direction or when the sudden steering is performed only in any one direction, the process (b) and the process are performed. Since the flags F1 and F2 in (c) are not ON at the same time, the determination in step 120 is no, and the correction of the calculation of the spin state quantity in the process (e) described later is not executed. Become. Further, after a predetermined period of time Tht1 or Tht2 has elapsed since the sudden steering is performed on either side, the determination in step 100 becomes yes, and also in this case, the correction of the calculation of the spin state quantity in the process (e) is executed. (In this case, all flag settings up to that point are reset (step 110)). However, when the sudden steering is performed in another direction before the predetermined period Tht1 or Tht2 has elapsed since the sudden steering is performed in either one of the steps, the flags F1 and F2 are simultaneously turned on. The determination of 100 is yes and the determination of step 120 is no. Thus, it is determined that there is the first sudden steering and the second sudden steering is performed within a short period of time, and the calculation of the spin state quantity by the process (e) is performed. Correction will be performed.

In the process (e) for correcting the calculation of the spin state quantity, as mentioned above, the contribution of the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle in the spin state quantity In order to reduce the value, the value of the coefficient K3 is set to zero. However, when the process (e) is executed first, immediately after the second sudden steering, that is, the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle is a predetermined threshold value. The absolute value of the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle is still a large value immediately after exceeding the range th1 to -th1. It is not preferable to forcibly set the value of the second-order differential term K3 · d ² β / dt ² to zero. Therefore, in the process (e), first, it is detected when the value of the second-order differential value K3 · d ² β / dt ² of the vehicle body slip angle becomes small or when the sign of such value is reversed. Is done. Specifically, the absolute value of the second-order differential term K3 · d ² β / dt ² of the vehicle body slip angle is | K3 · d ² β / dt ² | <th2 (5)
It is determined whether or not the condition is satisfied (step 130). Here, th2 is a constant smaller than a predetermined threshold th1 that may be arbitrarily set. Then, when the formula (5) is satisfied while the processing cycle is repeated, the flag F3 is set to ON in order to store that fact (step 140). When F3 is set to ON, the determination in step 150 becomes yes, and the value of the coefficient K3 is forcibly set to 0 (step 160: K3 ← 0). This state is maintained until the counter T1 or T2 counts the predetermined period Tht1 or Tht2, that is, until the predetermined period elapses after the first sudden steering (the elapse of the predetermined period). After that, it is canceled.)

Then, after the above series of processes, in the process (f), the spin state quantity is calculated using the formula (1). When K3 is forcibly set to 0 by the process (e), the second-order differential term K3 · d ² β / dt ² of the vehicle body slip angle is ignored, and the spin state quantity SP is
SP = K1 · β + K2 · dβ / dt (1 ')
It should be understood that

The processing in the above processing (a) to (f) is organized as follows corresponding to the steering state of the vehicle illustrated in FIG. 2 (b).
(I) The term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle when sudden steering is not performed or before it is performed does not deviate from the predetermined threshold range th1 to -th1, F1, All F2 are OFF. Therefore, it is determined as NO in step 120, and the spin state quantity is calculated using the term K3 · d ² β / dt ² of the ^second derivative value of the vehicle body slip angle as it is.
(Ii) When sudden steering is performed on either side-the second-order differential value K3 · d ² β / dt ^{2 of the} vehicle body slip angle deviates from one side of the predetermined threshold range th1 to -th1 ( In FIG. 2B, deviation from the th1 side), only one of F1 and F2 is set to ON, and the time measurement by the counter T1 or T2 is started. At this stage, it is still determined NO in step 120, and the spin state quantity is calculated using the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle as it is.
(Iii) When sudden steering is performed in another direction after the sudden steering is performed in one direction and before a predetermined period of time has elapsed—the term K3 · d ² of the second-order differential value of the vehicle body slip angle β / dt ² deviates from the other side of the predetermined threshold range th1 to −th1 (in FIG. 2B, deviates from the −th1 side), and both F1 and F2 are set to ON, The determination in step 120 is yes. However, at this stage, the absolute value of the second-order differential term K3 · d ² β / dt ² of the vehicle body slip angle is still larger than the predetermined value th2, and the flag F3 remains OFF. No is determined, and the spin state quantity is calculated using the term K3 · d ² β / dt ² of the ^second derivative value of the vehicle body slip angle as it is.
(Iv) when the second floor code sections K3 · d ² β / dt ² of the derivative of the vehicle body slip angle is reversed - the absolute value of the term K3 · d ² β / dt ² of the second order derivative of the vehicle body slip angle It becomes smaller than the predetermined value th2, and the flag F3 is turned on (steps 130 and 140). If so, the determination in step 150 is yes, K3 is set to 0, and the spin state quantity is calculated ignoring the term K3 · d ² β / dt ² of the ^second derivative of the vehicle body slip angle.
(V) When a predetermined period has elapsed since the first sudden steering-the determination in step 100 is YES and the spin state quantity uses the second-order differential value term K3 · d ² β / dt ² of the vehicle body slip angle as it is. Is calculated. In this case, the flag and counter settings up to that point are reset as shown in step 110 in FIG. 3 (a predetermined period has elapsed since the first sudden steering operation and without the second sudden steering operation). The same is sometimes true.)

Thus, according to the configuration of the above processing, when the sudden steering is executed twice in different directions within a (short) predetermined period, the second stage of the vehicle body slip angle is subsequently calculated in the calculation of the spin state quantity. The term K3 · d ² β / dt ^{2 of the} differential value is ignored. As a result, the spin state quantity is not affected by the early increase in the term K3 · d ² β / dt ² of the second-order differential value of the vehicle body slip angle after two sudden steerings, that is, temporarily reduced. Instead, the transition is as indicated by the dotted dotted line labeled “After correction” in FIG. As a result of the correction of the spin state amount, the control amount of each wheel for spin suppression is increased as shown by the round dotted line labeled “After correction” in FIGS. 2 (d) and 2 (e). In this case, there is no temporary reduction, and it is expected that the delay in convergence in the yaw rate will be eliminated.

  By the way, referring to the transition of the vehicle body slip angle term, the vehicle body slip angle differential value, and the vehicle body slip angle second-order differential value term in FIG. 2B, the vehicle body slip angle second-order differential value term. The reason for temporarily reducing the magnitude of the spin state quantity is that the sign of the second-order derivative value of the vehicle body slip angle is opposite to both the sign of the vehicle body slip angle and the sign of the derivative value of the car body slip angle. It is observed that this is because. Therefore, in the flowchart of FIG. 3, in the determination of step 130, the sign of the second derivative value of the vehicle body slip angle is the sign of the vehicle slip angle term and the sign of the vehicle slip angle derivative. It may be determined whether or not it is the opposite of both. Specifically, the determination is that the term of the vehicle body slip angle and the sign of the differential value of the vehicle body slip angle match, and the sign of the term of the second derivative value of the vehicle body slip angle is reversed. May be done by detecting.

  While the present invention has been described in detail with respect to one embodiment thereof, it will be apparent to those skilled in the art that various modifications can be made within the scope of the present invention.

For example, in the present embodiment, after the sudden steering is executed twice in different directions within a (short) predetermined period, the second-order differential value of the vehicle body slip angle is calculated in the calculation of the spin state quantity. When reducing the contribution of K3 · d ² β / dt ² , the value of the term is not completely ignored, but the value of the term is simply reduced to half or less than the normal value. You can just do it. Further, the spin state quantity is not limited to the linear sum in the form of the formula (1), but is expressed in other forms that are temporarily reduced by the change in the second-order derivative value of the vehicle body slip angle described above. It should be understood that such cases are also within the scope of the present invention. Furthermore, in this embodiment, the yaw moment for suppressing the spin is given by the difference in braking force between the left and right wheels, but the vehicle is equipped with a device that can automatically adjust the wheel steering angle. In this case, a yaw moment for suppressing spin may be generated by adjusting the wheel steering angle.

FIG. 1A is a schematic view of a vehicle on which a preferred embodiment of the behavior control device of the present invention is mounted, and FIG. 1B is a diagram of a vehicle incorporating the preferred embodiment of the behavior control device according to the present invention. It is a control block diagram of an electronic control unit. FIG. 2 shows the steering angle (a), the amount of spin state and the terms (b) constituting the steering wheel when the steering angle is changed to the left after the steering angle is changed to the right by sudden steering. The control amount (left front wheel braking force) (c), the right wheel control amount (right front wheel braking force) (d), and the yaw rate (e) are shown. In the figure, solid bold lines are changes in values when the calculation process of the spin state quantity according to the present invention is not corrected, and the round dotted lines in (b), (d), and (e) are FIG. 5 shows changes in values when the spin state quantity calculation processing according to the present invention is corrected. Further, in (b), the settings of the flags F1, F2, and F3 used in the calculation processing of the spin state quantity according to the present invention are shown superimposed. FIG. 3 is a flowchart showing the calculation process of the spin state quantity in the preferred embodiment of the behavior control apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle 12FL-RR ... Wheel 28 ... Differential device 30 ... Steering device 34 ... Booster, steering angle sensor 36L, R ... Tie rod 40 ... Braking device 42FL-RR ... Each wheel wheel cylinder 46 ... Hydraulic circuit 50 ... Electronics Control device 62 ... Lateral acceleration sensor 64 ... Yaw rate sensor

Claims (9)

  A vehicle behavior control device for suppressing vehicle spin based on a control amount calculated from a vehicle body slip angle, a differential value of the vehicle body slip angle, and a second-order differential value of the vehicle body slip angle, Steering is performed in a direction opposite to the one direction within a predetermined period after steering is performed in one of the directions and the magnitude of the second-order differential value of the vehicle body slip angle exceeds a predetermined value. When the second-order differential value of the vehicle body slip angle that is executed exceeds the predetermined value, the contribution of the second-order differential value of the vehicle body slip angle to the control amount is reduced. .   2. The apparatus according to claim 1, wherein steering is performed in one of the left and right directions of the vehicle and a second period differential value of the vehicle body slip angle exceeds a predetermined value within a predetermined period. When the steering is executed in the direction opposite to the one direction and the magnitude of the second derivative value of the vehicle body slip angle exceeds the predetermined value, the second derivative value of the vehicle body slip angle at the control amount. A device characterized in that its contribution is ignored.   3. The apparatus according to claim 1 or 2, wherein the steering is executed in one of the left and right directions of the vehicle, and a second-order differential value of the vehicle body slip angle exceeds a predetermined value. When steering is performed in a direction opposite to the one direction within the period and the magnitude of the second derivative of the vehicle body slip angle exceeds the predetermined value, the second derivative of the vehicle body slip angle is further increased. The apparatus is characterized in that the contribution of the second derivative of the vehicle body slip angle to the control amount is reduced when the magnitude becomes smaller than a second predetermined value smaller than the first predetermined value.   4. The apparatus according to claim 1, wherein the reduction of the contribution of the second-order differential value of the vehicle body slip angle in the control amount is canceled after the predetermined period has elapsed. apparatus.   5. The apparatus according to claim 1, wherein the sign of the second-order differential value of the vehicle body slip angle in the control amount is both the vehicle body slip angle and the vehicle body slip angle differential value. The apparatus is characterized in that the contribution of the second-order differential value of the vehicle body slip angle in the control amount is reduced when the sign is reversed. A device of any of claims 1 to 5, wherein the control amount is, the vehicle body slip angle beta, and the differential value d.beta / dt of the vehicle body slip angle, the second floor of the vehicle body slip angle differential value d ² beta / dt ² And using predetermined coefficients K1, K2, and K3,
K1 · β + K2 · dβ / dt + K3 · d ² β / dt ²
A device characterized by being given by:   7. The apparatus according to claim 6, wherein the value of the coefficient K3 is set to 0 when the contribution of the second-order differential value of the vehicle body slip angle in the controlled variable is reduced.   The apparatus according to claim 1, wherein a yaw moment that suppresses spin of the vehicle is generated based on the control amount.   The apparatus according to claim 1, wherein acceleration of the vehicle is limited based on the control amount.

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