JP5359492B2 - Vehicle motion control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motion control device for a vehicle capable of executing reliable vehicle stability control by compensating responsiveness of a brake actuator by preliminary control capable of suppressing an uncomfortable feeling to a driver. <P>SOLUTION: A first state quantity is calculated based on an actual turning state quantity, an over steer tendency of the vehicle is identified based on this first state quantity, and a vehicle stability control for suppressing the over steer tendency is executed. Moreover, a second state quantity different from the first state quantity is calculated based on the actual turning state quantity of the vehicle, the over steer tendency of the vehicle is identified based on this second state quantity, and preliminary control for compensating the responsiveness of the vehicle stability control is executed. The second state quantity identifies the yawing motion of the vehicle relatively faster in comparison with the first state quantity. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a vehicle motion control apparatus.

  Patent Document 1 states that “the response of the behavior control by the braking force is good by operating the pump means when the condition that causes the deterioration of the vehicle behavior is satisfied, not at the stage when the vehicle behavior actually deteriorates to some extent. For the purpose of “ensuring the performance”, “the means for detecting the steering angle, the means for detecting the steering angular velocity, the magnitude of the steering angle is equal to or greater than the reference value, and the magnitude of the steering angular velocity is equal to or greater than the reference value. Then, the operation of the pump means is started ".

  In Patent Document 2, it is determined whether or not there is a tendency to become an unstable traveling state based on rapid steering (steering start) in a stable traveling state. It is described that “preliminary brake intervention” is performed based on the maximum value of the steering wheel angular velocity or the like in order to “preliminarily perform brake intervention”.

  Patent Document 3 states that “the desired target brake torque acts only after a predetermined time as a function of the brake device because the brake pressure can be increased only with a finite gradient. In characteristic maneuvering, the vehicle may slip and may lead to results that cannot be stabilized quickly enough. " For the purpose of “stabilizing the vehicle more rapidly in dangerous driving situations”, “the vehicle lateral acceleration and the steering speed are determined and monitored with thresholds, and the vehicle lateral acceleration is The pre-brake pressure is formed when the threshold value is exceeded and the steering speed is below a predetermined threshold value. "

Japanese Patent No. 3114647 Japanese Patent No. 4119244 Special table 2007-513002 gazette

  In the above patent document, for example, in a situation where an obstacle must be urgently avoided, the start of vehicle stability control is predicted based on the steering angular velocity and the like, and the response of the actuator before the start of execution Describes a control (hereinafter, also referred to as a preliminary control) for applying a preliminary braking torque for compensating the performance. In this preliminary control, a braking torque at a low level is given. However, sound and vibration are generated when the actuator is actuated. Therefore, when the vehicle stability control is not executed even though the preliminary control is performed, the driver may feel uncomfortable. In view of the above-described problems, an object of the present invention is to provide a vehicle motion control device that can suppress a sense of discomfort to the driver and can perform reliable vehicle stability control.

  The vehicle motion control apparatus according to the present invention includes a braking unit B10 that applies braking torque to the wheels of the vehicle, and an actual turning state amount acquisition unit B20 that acquires an actual turning state amount (Yra, Gya, etc.) that acts on the vehicle. The first state quantity Jos is calculated based on the actual turning state quantity, and the first identifying means B30 for identifying the oversteer tendency of the vehicle based on the first state quantity Jos. Further, the present device calculates a second state quantity Kos different from the first state quantity Jos based on the actual turning state quantity (Yra, Gya, etc.) of the vehicle, and oversteering the vehicle based on the second state quantity Kos. Second identifying means B40 for identifying a tendency, steering angular speed obtaining means B50 for obtaining the steering angular speed dSa of the vehicle, and control means B60 for controlling the braking torque of the wheels by controlling the braking means B10. The control unit B60 controls the braking torque of the wheels via the braking unit B10 based on the identification results Fj and Jos of the first identification unit B30, and executes vehicle stability control that maintains the stability of the vehicle. Further, the control unit B60 controls the braking unit B10 based on the identification result Fk of the second identification unit B40 and the steering angular velocity dSa, and applies the braking torque that improves the responsiveness of the vehicle stability control.

  When the preliminary control is executed, the driver may feel uncomfortable due to the driving sound of the actuator or the like or the slight deceleration of the vehicle by the preliminary control. The case where the preliminary control is required is an oversteer case in which a rapid yawing behavior occurs. Therefore, when the steering angular velocity dSa is large and the start of vehicle stability control (main control) is predicted, the state quantity (second state) different from the state quantity (first state quantity Jos) used for execution of the main control is predicted. Based on the quantity Kos), an oversteer tendency with an abrupt yawing movement is determined. Therefore, a rapid increase in oversteer tendency can be determined early by the second state quantity Kos, and the execution of the preliminary control can be started quickly.

1 is a diagram illustrating an overall configuration of a vehicle motion control apparatus according to an embodiment of the present invention. It is a figure for demonstrating the steering operation of J turn steering which avoids an obstacle urgently. It is a figure for demonstrating steering operation of the lane change steering which urgently avoids an obstruction. 1 is a diagram illustrating an overall configuration of a vehicle including a vehicle motion control device according to an embodiment of the present invention. It is a figure which shows the whole structure of the brake actuator shown in FIG. 4 in embodiment of this invention. It is a functional block diagram which shows the process example of the motion control (vehicle stability control) of the vehicle which concerns on embodiment of this invention. FIG. 7 is a control flow diagram illustrating a processing example of the vehicle stability control calculation illustrated in FIG. 6 in the embodiment of the present invention. FIG. 8 is a control flow diagram illustrating a processing example of start determination of preliminary control illustrated in FIG. 7 in the embodiment of the present invention. FIG. 8 is a control flow diagram illustrating an example of processing for determining the end of preliminary control illustrated in FIG. 7 in the embodiment of the present invention. It is a figure for demonstrating the effect | action and effect in the case of J turn steering in embodiment of this invention. It is a figure for demonstrating the effect | action and effect in the case of lane change steering in embodiment of this invention. It is a figure which shows the example of a map for calculating the threshold value (4th predetermined value) for determining the start of preliminary | backup control based on an actual lateral acceleration in embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a vehicle motion control apparatus according to an embodiment of the present invention.

  In FIG. 1, a vehicle motion control device (hereinafter referred to as “this device”) obtains a braking means B10 that applies braking torque to the wheels of the vehicle and an actual turning state amount (Yra, Gya, etc.) that acts on the vehicle. An actual turning state quantity acquisition means B20 that calculates the first state quantity Jos based on the actual turning state quantity, and a first identification means B30 that identifies the oversteer tendency of the vehicle based on the first state quantity Jos. Prepare. Further, the present device calculates a second state quantity Kos different from the first state quantity Jos based on the actual turning state quantity (Yra, Gya, etc.) of the vehicle, and oversteering the vehicle based on the second state quantity Kos. Second identifying means B40 for identifying a tendency, steering angular speed obtaining means B50 for obtaining the steering angular speed dSa of the vehicle, and control means B60 for controlling the braking torque of the wheels by controlling the braking means B10. The control unit B60 controls the braking torque of the wheels via the braking unit B10 based on the identification results Fj and Jos of the first identification unit B30, and executes vehicle stability control that maintains the stability of the vehicle. Further, the control unit B60 controls the braking unit B10 based on the identification result Fk of the second identification unit B40 and the steering angular velocity dSa, and applies the braking torque that improves the responsiveness of the vehicle stability control. Here, in the control means B60, the steering angular velocity dSa (absolute value thereof) is larger than a first predetermined value (predetermined values dsa1, dsa2, dsa3 described later), and the identification result Fk of the second identification means B40 tends to oversteer. When shown (Fk = 1), braking torque can be applied to the wheels.

  The second discriminating means B40 discriminates a relatively fast vehicle yawing movement compared to the first discriminating means B30. The first discriminating means B30 is a state quantity indicating the magnitude of the yawing motion of the vehicle (for example, a skid angle βa, a side slip angle deviation Δβ) and a state quantity indicating the speed of the yawing motion of the vehicle (for example, the skid angular velocity dβa, yaw rate). The first (oversteer) state quantity Jos is calculated based on the correlation with the deviation ΔYr). Specifically, the first state quantity Jos1 is calculated by an arithmetic expression including a state quantity including a side slip angle term (of the vehicle body) and a state quantity including a yaw rate term. In addition, the second identification unit B40 is configured to calculate the second (oversteer) state quantity Kos based only on the state quantity (for example, the side-slip angular velocity dβa, the yaw rate deviation ΔYr) representing the speed of the yawing motion of the vehicle. Has been. Specifically, the second state quantity Kos is calculated by an arithmetic expression composed of only the state quantity including the yaw rate term (not including the side slip angle term).

  The case where the preliminary control is required is an oversteer case in which a rapid yawing behavior occurs. In the main control of the vehicle stability control, it is necessary to identify an oversteer tendency accompanied by a relatively gentle yawing motion. Based on a second state quantity Kos different from the first state quantity Jos used for the main control, an oversteer tendency accompanied by a sudden change in yawing motion is determined. By the second state quantity Kos, a rapid increase in oversteer tendency is determined at an early stage, and the execution of the preliminary control can be started quickly.

  This apparatus includes steering angle acquisition means B70 for acquiring the steering angle Sa of the vehicle. The control means B60 can apply the braking torque when the steering angle Sa (absolute value) decreases and the steering angle Sa (absolute value) is smaller than a second predetermined value (predetermined value sa1 described later). . The steering angular velocity acquisition unit B50 can calculate the steering angular velocity dSa based on the steering angle Sa acquired by the steering angle acquisition unit B70.

  This device determines whether the steering direction Dstr of the vehicle is one direction or the other direction (the direction opposite to the one direction) based on the steering angle Sa acquired by the steering angle acquisition unit B70. Steering direction determination means B80 is provided. The control means B60 determines that the steering direction Dstr is continuously one direction after the steering direction determination means B80 determines that the steering direction Dstr is one direction, the steering angle Sa (absolute value) increases, and the steering angle Sa ( The braking torque can be applied when the absolute value is smaller than a third predetermined value (a predetermined value sa2 described later).

  A sudden yawing behavior is likely to occur when the steering operation is performed from one direction to the other direction. By adding the magnitude of the steering angle to the start condition, it can be reliably determined that the steering operation is performed from one direction to the other direction.

  This apparatus includes yaw angular acceleration calculation means B90 that acquires the yaw angular acceleration dYr of the vehicle. The yaw angular acceleration dYr can be calculated based on the actual turning state amount (yaw rate Yra) acquired by the actual turning state amount acquisition unit B20. The control means B60 can apply the braking torque of the wheel when the yaw angular acceleration dYr (absolute value thereof) is larger than a fourth predetermined value (predetermined values dyr1, dyr2, dyr3 described later). Since the yaw angular acceleration dYr represents a change in yawing motion, reliable preliminary control can be executed by considering the condition of the yaw angular acceleration dYr.

  First, with reference to FIG.2 and FIG.3, steering operation in the case of avoiding an obstacle urgently is demonstrated. FIG. 2 is referred to as J-turn steering, and is a case where the steering wheel operation is suddenly performed in one direction (for example, the left steering direction). The steering operation by the driver is started at time p0, and the steering angle Sa (steering wheel angle θsw or steering wheel rudder angle δfa) is “0 (steering neutral position, corresponding to the vehicle going straight until time p2”. ”), And then reaches a steady value. The steering angular velocity (time differential value of the steering angle) dSa at this time rises from “0” at time p0, reaches a maximum value at time p1, and returns to “0” at time p2. Here, the steering operation direction may be a right steering direction and a left steering direction, and the vehicle turning direction may be a right turning direction and a left turning direction. They are generally given positive and negative signs. For example, the left steering direction and the left turning direction are represented as positive signs, and the right steering direction and the right turning direction are represented as negative signs. However, when describing the magnitude relationship of the values or the increase / decrease in the values, it becomes very complicated when the sign is taken into account. Therefore, unless there is a particular limitation, the absolute value magnitude relationship and the absolute value increase / decrease are represented. The predetermined value is a positive value.

  FIG. 3 is called lane change steering, and after a steering wheel operation is suddenly performed in one direction (for example, the left steering direction), another direction (for example, the right steering direction) opposite to the one direction continuously. This is a transitional steering operation in which a steering wheel operation is performed. At time q0, the steering operation by the driver is started in one direction (one steering direction). The steering angle Sa is increased in one steering direction from “0 (neutral position of steering, corresponding to straight traveling of the vehicle)” until time q1, and returned to “0” after time q1. Further, the steering operation is started in the other direction (other steering direction) continuously at time q2. The steering angle Sa is increased from “0” to the other steering direction from time q2 to q3, returned to “0” after time q3, and becomes “0” again at time q4. Here, an operation that is steered in one direction first is referred to as “first steering”, and an operation that is steered in the other direction continuously after this “first steering” is referred to as “second steering”. A continuous steering operation when the first steering and the second steering are performed is referred to as “transient steering”. Furthermore, when the steering angle Sa moves away from “0 (steering neutral position)” (when the magnitude (absolute value) of the steering angle Sa increases), the “cutting” state and the steering angle Sa are “0 (steering neutral position)”. (Position) ”(when the magnitude (absolute value) of the steering angle Sa decreases) is called a“ switchback ”state. There is a high probability that the vehicle stability control is executed when the steering angular speed dSa at the time of turning back the first steering or at the time of turning the second steering is high. On the other hand, as shown by the broken line in FIG. 3, when the second steering is not performed after the first steering is performed (that is, when the transient steering is not performed), even if the steering angle speed is equivalent, The possibility of requiring vehicle stability control is low.

  FIG. 4 is a diagram illustrating an overall configuration of a vehicle including a vehicle motion control device (hereinafter referred to as “the present device”) according to an embodiment of the present invention. The subscript “**” added to the end of various symbols, etc. indicates whether the various symbols are related to any of the four wheels, “fl” is the left front wheel, and “fr” is the right front wheel. , “Rl” indicates the left rear wheel, and “rr” indicates the right rear wheel.

  This device includes a wheel speed sensor WS ** that detects a wheel speed Vw ** and a steering wheel SW that detects a rotation angle θsw of the steering wheel SW (from a neutral position “0” of the steering device corresponding to straight traveling of the vehicle). A wheel angle sensor SA, a front wheel steering angle sensor SB that detects the steering angle δfa of the steered wheel (front wheel), a steering torque sensor ST that detects torque Tsw when the driver operates the steering wheel SW, and a vehicle A yaw rate sensor YR that detects the actual yaw rate Yra that acts, a longitudinal acceleration sensor GX that detects longitudinal acceleration Gxa in the longitudinal direction of the vehicle body, a lateral acceleration sensor GY that detects actual lateral acceleration Gya in the lateral direction of the vehicle body, and a wheel cylinder Wheel cylinder pressure sensor PW ** for detecting the brake fluid pressure Pw ** of WC ** and the rotational speed of the engine EG An engine rotation speed sensor NE that detects Ne, an acceleration operation amount sensor AS that detects an operation amount As of a driver's acceleration operation member (accelerator pedal) AP, and an operation amount of a driver's braking operation member (brake pedal) BP A brake operation amount sensor BS for detecting Bs, a shift position sensor HS for detecting the shift position Hs of the speed change operation member SF, and a throttle position sensor TS for detecting the opening Ts of the throttle valve of the engine are provided.

  The apparatus also includes a brake actuator BRK for controlling the brake fluid pressure, a throttle actuator TH for controlling the throttle valve, a fuel injection actuator FI for controlling fuel injection, and an automatic transmission AT for controlling the shift. ing.

  In addition, the apparatus includes an electronic control unit ECU. The electronic control unit ECU is a microcomputer composed of a plurality of independent electronic control units ECU (ECUb, ECUs, ECUe, ECUa) connected to each other via a communication bus CB. The electronic control unit ECU is electrically connected to the above-described various actuators (such as BRK) and the above-described various sensors (such as WS **). Each system electronic control unit (ECUb, etc.) in the electronic control unit ECU executes a dedicated control program. Signals (sensor values) of various sensors and signals (internally calculated values) calculated in each electronic control unit (ECUb or the like) are shared via the communication bus CB.

  Specifically, the brake electronic control unit ECUb performs anti-skid control (ABS control), traction control (TCS control), etc. based on signals from the wheel speed sensor WS **, the yaw rate sensor YR, the lateral acceleration sensor GY, and the like. Slip suppression control (braking / driving force control) is executed. Further, based on the wheel speed Vw ** of each wheel detected by the wheel speed sensor WS **, the vehicle speed Vx is calculated by a known method. The steering electronic control unit ECUs executes well-known electric power steering control based on a signal from the steering torque sensor ST and the like. The engine electronic control unit ECUe executes control of the throttle actuator TH and the fuel injection actuator FI based on signals from the acceleration operation amount sensor AS and the like. The transmission electronic control unit ECUa executes control of the gear ratio of the automatic transmission AT.

  The brake actuator BRK has a known configuration including a plurality of electromagnetic valves (hydraulic pressure regulating valves), a hydraulic pump, an electric motor, and the like. When the brake control is not executed, the brake actuator BRK supplies the brake hydraulic pressure corresponding to the operation of the brake operation member BP by the driver to the wheel cylinder WC ** of each wheel, and the brake operation member for each wheel. (Brake pedal) A braking torque corresponding to the operation of the BP is applied. When executing brake control such as anti-skid control (ABS control), traction control (TCS control), or vehicle stability control (ESC control) that suppresses vehicle understeer and oversteer, the brake actuator BRK controls the brake pedal BP. Independently of the operation, the brake fluid pressure in the wheel cylinder WC ** can be controlled for each wheel WH **, and the brake torque can be adjusted for each wheel.

  Further, each wheel is provided with a well-known wheel cylinder WC **, brake caliper BC **, brake pad PD **, and brake rotor RT ** as braking means. By applying a brake fluid pressure to the wheel cylinder WC ** provided in the brake caliper BC **, the brake pad PD ** is pressed against the brake rotor RT **, and a braking torque is applied by the friction force. Note that the control of the braking torque is not limited to that based on the braking hydraulic pressure, and can be performed using an electric brake device.

  FIG. 5 is a diagram showing an overall configuration of the brake actuator BRK. When the driver depresses a braking operation member (for example, a brake pedal) BP, the pedaling force is boosted by the booster VB, and the master piston provided in the master cylinder MC is pushed. As a result, the same master cylinder pressure Pmc is generated in the first chamber and the second chamber defined by the master piston. The master cylinder pressure Pmc is applied to the wheel cylinder WC ** of each wheel WH ** through the brake actuator BRK.

  The brake actuator BRK has a first piping system HP1 connected to the first chamber of the master cylinder MC and a second piping system HP2 connected to the second chamber of the master cylinder MC. The first piping system HP1 controls the brake fluid pressure applied to the left front wheel WHfl and the right rear wheel WHrr. The second piping system HP2 controls the brake fluid pressure applied to the right front wheel WHfr and the left rear wheel WHrl. Since the first piping system HP1 and the second piping system HP2 have the same configuration, only the first piping system HP1 will be described below, and the description of the second piping system HP2 will be omitted. The configuration shown in FIG. 5 is a diagonal piping configuration, but the brake piping configuration may be front and rear piping.

  The first piping system HP1 includes a pipeline LA that generates braking hydraulic pressures (hydraulic pressures in the wheel cylinders) Pwfl and Pwrr. The pipe line LA is provided with a first differential pressure control valve SS1 that can be controlled between a communication state and a differential pressure state. Then, the master cylinder pressure Pmc is transmitted to the wheel cylinder WCfl provided in the left front wheel WHfl and the wheel cylinder WCrr provided in the right rear wheel WHrr. During normal braking in which the driver operates the brake pedal BP (when brake control is not being executed), the valve position of the first differential pressure control valve SS1 is adjusted to an open state so as to be in a communicating state. . When the first differential pressure control valve SS1 is energized, the valve position is adjusted to the closed state, and the first differential pressure control valve SS1 is set to the differential pressure state.

  The pipe line LA branches into two pipe lines LAfl and LArr on the side of the wheel cylinders WCfl and WCrr with respect to the first differential pressure control valve SS1. The line LAfl is provided with a first pressure increase control valve SZfl that controls the increase of the brake fluid pressure to the wheel cylinder WCfl. The pipe line LArr is provided with a second pressure increase control valve SZrr for controlling the increase of the brake fluid pressure to the wheel cylinder WCrr. The first and second pressure increase control valves SZfl, SZrr are constituted by two-position electromagnetic valves that can control the communication / blocking state. The first and second pressure-increasing control valves SZfl, SZrr are in a communication state (open state) when the supplied current is “0” (when not energized) and when current is passed (when energized). It is controlled to a shut-off state (closed state). The first and second pressure increase control valves SZfl, SZrr are so-called normally open types.

  The pipe LB is a pipe for pressure reduction that connects the first and second pressure increase control valves SZfl, SZrr, and the wheel cylinders WCfl, WCrr and the pressure regulating reservoir R1. The pipe LB is provided with a first pressure reduction control valve SGfl and a second pressure reduction control valve SGrr configured by two-position electromagnetic valves capable of controlling the communication / blocking state. The first and second pressure reduction control valves SGfl and SGrr are closed when not energized and opened when energized. These are so-called normally closed types.

  A pipeline LC is disposed between the pressure regulating reservoir R1 and the pipeline LA. A hydraulic pump OP1 is provided in the pipeline LC. The brake fluid is sucked from the pressure adjusting reservoir R1 by the hydraulic pump OP1 and discharged toward the master cylinder MC or the wheel cylinders WCfl and WCrr. The hydraulic pump OP1 is driven by an electric motor MT. A pipe line LD is provided between the pressure regulating reservoir R1 and the master cylinder MC. When automatic pressurization such as vehicle stability control or traction control is performed, the brake fluid is sucked from the master cylinder MC through the pipeline LD by the hydraulic pump OP1 and discharged to the pipelines LAfl and LArr. As a result, the brake fluid is supplied to the wheel cylinders WCfl and WCrr, the brake fluid pressure of the wheel cylinder WC ** of the target wheel is increased, and a braking torque is applied.

  When the preliminary control is executed, the electric motor MT is driven, and the brake fluid is sucked from the master cylinder MC by the hydraulic pump OP1 and discharged to the wheel cylinder WC **. As a result, a gap (also referred to as a pad gap) between the brake pad PD ** and the brake rotor RT ** is reduced, and a preliminary braking hydraulic pressure (also referred to as preload) is applied to the wheel cylinder WC **. .

  FIG. 6 is a functional block diagram showing a processing example of vehicle motion control (vehicle stability control) in the present embodiment. The vehicle stability control is composed of main control and preliminary control. The main control is control that suppresses an understeer tendency and / or an oversteer tendency of the vehicle. The preliminary control is for assisting the main control, and operates in advance of the main control to compensate for responsiveness. A functional block having the same number as the “means” in FIG. 1 has the same function as the means.

  In the target turning state amount calculation block B15, a target turning state amount (target turning state amount) Jrt of the vehicle is calculated using a known method. Here, the turning state amount is a state amount that represents the turning state of the vehicle, and is at least one of yaw rate, vehicle body side slip angle (also simply referred to as a side slip angle), and vehicle body side slip angular velocity (also simply referred to as a side slip angular velocity). This is a value calculated using. As the target turning state amount Jrt, the target yaw rate Yrt is calculated based on the vehicle speed Vx and the steering wheel angle θsw (or the front wheel steering angle δfa). Based on the steering wheel angle θsw (or the front wheel rudder angle δfa), a target side slip angle (target vehicle side slip angle) βt is calculated.

  In the actual turning state quantity acquisition block B20, the turning state quantity Jra actually acting on the vehicle is calculated based on the sensor value obtained via the communication bus CB and / or the internal calculation value of another electronic control unit. To be acquired. For example, the actual yaw rate Yra acting on the vehicle detected by the yaw rate sensor YR and the actual lateral acceleration Gya detected by the lateral acceleration sensor GY are acquired as the actual turning state quantity Jra. The target turning state quantity Jrt and the actual turning state quantity Jra correspond to each other.

  In the oversteer identification calculation block B35, based on the target turning state quantity Jrt and the actual turning state quantity Jra, the oversteer state quantity Jos indicating the degree of oversteering of the vehicle and the control indicating whether or not the vehicle tends to oversteer. Flags Fj and Fk are calculated. The control flag Fj represents the determination result of the oversteer tendency of the vehicle based on the first state quantity Jos. “Fj = 0” indicates that “the vehicle does not have an oversteer tendency (also referred to as a non-oversteer state)”, and “Fj = 1” indicates that “the vehicle has an oversteer tendency (also referred to as an oversteer state)”. Similarly, the control flag Fk represents the determination result of the oversteer tendency of the vehicle based on the second state quantity Kos. “Fk = 0” indicates that “the vehicle does not have an oversteer tendency (also referred to as a non-oversteer state)”, and “Fk = 1” indicates that “the vehicle has an oversteer tendency (also referred to as an oversteer state)”. The oversteer identification calculation block B35 includes a first identification calculation block B30 that uses the first state quantity Jos and a second identification calculation block B40 that uses the second state quantity Kos.

  First, the first oversteer identification calculation block B30 will be described. In the first oversteer identification calculation block B30, the first state quantity Jos calculated based on the mutual relationship between the state quantity representing the magnitude of the yawing motion and the state quantity representing the speed of the yawing motion is used as the turning state quantity. It is done. The first state quantity Jos is also used for control amount calculation (calculation of a braking torque target value for main control) in main control of vehicle stability control, which will be described later.

  On a road surface with a low coefficient of friction, the yawing motion may gradually increase. In order to properly control the vehicle stability even in such a situation, the determination of the oversteer tendency in the main control or the like is not limited to the speed of the yawing motion but also the first yawing motion. The state quantity Jos is calculated. Here, the “state quantity indicating the magnitude of the yawing motion” is a state quantity including the actual (vehicle body) side slip angle βa of the vehicle. Therefore, a side slip angle deviation Δβ, which will be described later, or an actual side slip angle βa itself corresponds to a “state quantity indicating the magnitude of the yawing motion”. The “state quantity representing the speed of the yawing motion” is a state quantity including the actual yaw rate Yra of the vehicle. Therefore, the yaw rate deviation ΔYr, which will be described later, or the side slip angular velocity dβa (= Yra−Gya / Vx, where Gya is the actual lateral acceleration and Vx is the vehicle speed) corresponds to the “state quantity indicating the speed of the yawing motion”. To do.

  In the first state quantity calculation block B31, the actual turning state quantity Jra and the target turning state quantity Jrt are compared, and the first state quantity Jos is calculated. Deviation between actual side slip angle βa and target side slip angle βt (referred to as side slip angle deviation) Δβ (= βa−βt), and deviation between actual yaw rate Yra and target yaw rate Yrt (referred to as yaw rate deviation) ΔYr (= Yra−Yrt) The first state quantity Jos (= K1 · Δβ + K2 · ΔYr, where K1 and K2 are coefficients) is calculated. Instead of the yaw rate deviation ΔYr, the side slip angular velocity dβa can be used. Since the target value βt of the side slip angle can be a constant (for example, the target value is “0”), the actual side slip angle βa itself can be used instead of the side slip angle deviation Δβ. The first state quantity Jos is calculated based on the mutual relationship between the state quantities Δβ, βa representing the magnitude of the yawing motion and the state quantities ΔYr, dβa representing the speed of the yawing motion. That is, the first state quantity Jos is calculated based on an arithmetic expression composed of both the state quantities Δβ, βa including the side slip angle term and the state quantities ΔYr, dβa including the yaw rate term. When the first state quantity Jos is calculated based on the mutual relationship between the actual side slip angle βa and the side slip angular speed dβa, the target turning state quantity Jrt (target turning state quantity calculation block B15) can be omitted.

  In the first determination calculation block B32, the vehicle oversteer tendency is determined based on the first state quantity (first oversteer state quantity) Jos. When the first state quantity Jos is larger than the predetermined value jos1, it is determined that the vehicle exhibits an oversteer tendency (referred to as an oversteer state). When the first state quantity Jos is equal to or less than the predetermined value jos1, it is determined that the vehicle is understeer or neutral steer and does not show an oversteer tendency (referred to as a non-oversteer state). When the vehicle is in the oversteer state (Jos> jos1), “1” is output as the first control flag (determination result of oversteer tendency based on the first state quantity) Fj. On the other hand, when the vehicle is in the non-oversteer state (Jos ≦ jos1), “0” is output as the first control flag Fj. In conjunction with the first control flag Fj, the first determination calculation block B32 outputs the first state quantity Jos to the vehicle stability control calculation block B65.

  Next, the second oversteer identification calculation block B40 will be described. In the second oversteer identification calculation block B40, the second state quantity Kos calculated based on the state quantity representing the speed of the yawing motion is used as the turning state quantity. The second state quantity Kos calculated in the second state quantity calculation block B41 is used to determine an oversteer tendency for preliminary control. Preliminary control is necessary only when an oversteer tendency with abrupt yawing behavior occurs. Therefore, the second state quantity Kos is calculated based only on the state quantity representing the speed of the yawing motion. The yaw rate deviation ΔYr (= Yra−Yrt) is used as the second state quantity Kos. Further, the side slip angular velocity dβa (= Yra−Gya / Vx) can be used as the second state quantity Kos. That is, the second state quantity Kos is calculated based on an arithmetic expression (state quantity ΔYr, dβa) that does not include the side slip angle term but includes only the yaw rate term.

  In the second determination calculation block B42, an oversteer tendency with a sudden yawing motion of the vehicle is determined based on the second state quantity (second oversteer state quantity) Kos. When the second state quantity Kos is larger than the predetermined value kos1, the oversteer state is determined. When the second state quantity Kos is equal to or less than the predetermined value kos1, it is determined that the non-oversteer state. When the vehicle is in an oversteer state (Kos> kos1), “1” is output as the second control flag (oversteer tendency determination result based on the second state quantity) Fk. On the other hand, when the vehicle is in the non-oversteer state (Kos ≦ kos1), “0” is output as the second control flag Fk.

  In the yaw angular velocity calculation block B90, the actual yaw rate Yra acquired in the actual turning state amount acquisition block B20 is time-differentiated to calculate the yaw angular acceleration dYr. The yaw angular acceleration dYr can be obtained directly from the sensor and / or other electronic control unit via the communication bus CB. The yaw angular acceleration dYr and the actual lateral acceleration Gya acquired in the actual turning state quantity acquisition block B20 are input to the vehicle stability control calculation block B65 (preliminary control calculation block B60).

  In the steering angle acquisition block B70, the steering angle Sa is acquired based on a sensor signal obtained via the communication bus CB and / or an internal calculation value of another electronic control unit. The steering angle Sa is determined based on at least one of the steering wheel angle θsw and the steering angle δfa of the steered wheel (front wheel). In the steering angular velocity calculation block B50, the steering angle Sa is time-differentiated to calculate the steering angular velocity dSa. The steering angular velocity dSa is determined based on at least one of the steering wheel angular velocity dθsw and the steered wheel steering angular velocity dδfa. The steering angular velocity dSa can be obtained directly from the sensor and / or other electronic control unit via the communication bus CB. In the steering direction determination calculation block B80, the steering direction Dstr is calculated based on the steering angle Sa. As the steering direction Dstr, any one of the straight traveling direction, the left steering direction, and the right steering direction is determined. The steering angle Sa, the steering angular velocity dSa, and the steering direction Dstr are input to the vehicle stability control calculation block B65 (preliminary control calculation block B60).

  In the vehicle stability control calculation block B65, a target value Pwt ** of the braking torque to be applied to the wheels is calculated based on the state quantity (Jos or the like) in order to maintain the vehicle stability. The vehicle stability control calculation block B65 includes a main control calculation block B61, a preliminary control calculation block B60, and an adjustment calculation block B62. In the main control calculation block B61, based on the first (oversteer) state quantity Jos, the target value (main control) of the braking torque of each wheel that serves as a basis for stabilizing the vehicle (in particular, suppressing the oversteer tendency of the vehicle). Qmt ** (referred to as target value) is calculated. In the preliminary control calculation block B60, a preliminary braking torque target value (referred to as a preliminary control target value) Qpt ** for compensating the response of the brake actuator BRK is calculated. In the adjustment calculation block B62, the main control target value Qmt ** and the preliminary control target value Qpt ** are adjusted, and a final braking torque target value (referred to as final target value) Pwt ** is calculated. Further, the vehicle speed Vx and the braking operation amount Bs are input to the vehicle stability control calculation block B65.

  In the main control calculation block B61, based on the first oversteer state quantity (first state quantity) Jos, a main control target value Qmt ** which is the main of vehicle stability control (oversteer suppression control) is set in advance. Calculated using a map. This calculation map shows that the main control target value Qmt ** is set to “0” when the first state quantity Jos is less than the predetermined value jos1 (threshold value), and the oversteer state quantity Jos is greater than or equal to the predetermined value jos1. Is set as a characteristic in which the main control target value Qmt ** is increased from “0” as the first state quantity Jos increases. The predetermined value jos1 is a start determination condition for the main control of the vehicle stability control (a condition for determining the oversteer state based on the first state quantity and starting applying the braking torque). The main control target value Qmt ** can be input to the preliminary control calculation block B60.

  In the preliminary control calculation block B60, the preliminary control target value Qpt ** is calculated in order to compensate the responsiveness of the brake actuator BRK by accelerating the start of applying the braking torque by the main control. Control flag Fj, Fk, yaw angular acceleration dYr, actual lateral acceleration Gya, steering angle Sa, steering angular velocity dSa, and steering direction Dstr are input to the preliminary control calculation block B60. The preliminary control calculation block B60 includes a start determination calculation block and an end determination calculation block. Details of the preliminary control will be described later.

  In the adjustment calculation block B62, the final target value Pwt ** is calculated based on the main control target value Qmt ** and the preliminary control target value Qpt **. Specifically, the larger one of the target value Qmt ** and the target value Qpt ** is selected, and the final target value Pwt ** is calculated. Alternatively, the final target value Pwt ** can be calculated by adding the target value Qpt ** to the target value Qmt **. The target values Qmt **, Qpt **, and Pwt ** can be calculated as any of wheel braking force, braking torque, braking fluid pressure, front / rear slip, wheel speed, and brake pad thrust.

  In the braking torque adjusting means (corresponding to the braking means) B10, based on the final target value Pwt ** of the braking torque, the driving means for the brake actuator BRK (for example, the electric motor for driving the hydraulic pump, the driving means for the solenoid valve) Is controlled. Based on the target value Pwt ** and the actual value Pwa ** by providing a sensor (for example, a pressure sensor PW **) for detecting the actual value Pwa ** of the braking torque corresponding to the target value Pwt ** on the wheel. Thus, the driving means can be controlled so that the actual value Pwa ** coincides with the target value Pwt **.

  The preliminary control calculation block B60 in FIG. 6 will be described with reference to FIG.

  First, in step S110, the first control flag Fj and the first state quantity Jos are read as the calculation result (first identification calculation result) of the first oversteer identification calculation block. At this time, the control state Qmt ** of the main control can be read. Whether or not the main control has already been started, and if so, how much braking torque has been applied to which wheel can be read.

  In step S120, the second control flag Fk is read as the calculation result (second identification calculation result) of the second oversteer identification calculation block. In step S130, the vehicle speed Vx, the braking operation amount Bs, and the (actual) lateral acceleration Gya are read. In step S140, the steering angle Sa (steering wheel operation angle θsw or front wheel steering angle δfa), steering angular velocity dSa (steering wheel operation angular velocity dθsw or front wheel steering angular velocity dδfa), and yaw angular acceleration dYr are read. . In step S150, the steering direction Dstr is calculated based on the steering angle Sa. For example, the steering direction is determined based on the sign of the steering angle Sa. When the sign of the steering angle Sa is a positive sign (+), the left steering direction (corresponding to the left turn of the vehicle) is determined, and when the sign of the steering angle Sa is a negative sign (-), the right steering is performed. A direction (corresponding to a right turn of the vehicle) is determined.

  In determination steps S160, S170, and S180, the start and / or end of the main control of the vehicle stability control is determined. In step S160, it is determined whether the main control is currently being executed. If the main control is not executed and a negative determination (No) is made in step S160, the calculation process proceeds to step S170. In step S170, it is determined whether a start condition for main control is satisfied. The start of the main control is determined when the first state quantity Jos exceeds the predetermined value jos1. If the start of main control is affirmed in step S170 (Yes), the calculation process proceeds to step S190, and main control is started. Here, when the preliminary control is being executed, the execution of the preliminary control is terminated and the main control is started. In the main control, a preset calculation map (see the main control calculation block B61 in FIG. 6) is output as the main control target value Qmt **. On the other hand, if the start of the main control is denied (No) in step S170, the main control is not started and the process proceeds to step S200.

  If the main control is being executed and an affirmative determination (Yes) is made in step S160, the arithmetic processing proceeds to step S180. In step S180, it is determined whether the main control end condition is satisfied. The end of the main control is determined by the first state quantity Jos being equal to or less than a predetermined value jos1. If the end of the main control is affirmed in step S180 (Yes), the main control is ended in step S240, and the main control target value Qmt ** is returned to “0”. On the other hand, if the end of the main control is denied (No) in step S180, the calculation process proceeds to step S190, and the main control is continued.

  Next, in determination steps S200, S210, and S220, the start and / or end of preliminary control is determined. In step S200, it is determined whether the preliminary control is currently being executed. If the preliminary control is not executed and a negative determination (No) is made in step S200, the arithmetic processing proceeds to step S210. In step S210, it is determined whether the preliminary control start condition is satisfied. The start conditions for the preliminary control will be described later. If the start of the preliminary control is affirmed in step S210 (Yes), the calculation process proceeds to step S230, and the preliminary control is started. In the preliminary control, a predetermined value set in advance is output as the preliminary control target value Qpt **. When the preliminary control is executed, for example, the pad gap is closed and a preliminary braking torque is generated. Thereby, the response of the brake actuator BRK is compensated. On the other hand, if the start of the preliminary control is denied (No) in step S210, the preliminary control is not started.

  If the preliminary control is being executed and an affirmative determination (Yes) is made in step S200, the arithmetic processing proceeds to step S220. In step S220, it is determined whether the preliminary control end condition is satisfied. Preliminary control end conditions will be described later. If the end of the preliminary control is affirmed in step S220 (Yes), the preliminary control is ended in step S250, and the preliminary control target value Qpt ** is returned to “0”. On the other hand, if the end of the preliminary control is denied in step S220 (No), the calculation process proceeds to step S230, and the preliminary control is continued.

  The preliminary control start determination step S210 in FIG. 7 (corresponding to the start determination calculation block of the preliminary control calculation block B60 in FIG. 6) will be described with reference to FIG. The start determination of the preliminary control is performed for each wheel. As described above, when explaining the magnitude relationship of the values, or the increase and decrease of the values, the steering direction represented by the positive and negative signs and the turning direction are considered very complicated. When there is no limitation, it represents a magnitude relationship between absolute values and increases and decreases in absolute values, and the predetermined value is a positive sign (+) value.

  In step S310, based on the read second control flag Fk, it is determined whether the vehicle is in an oversteer tendency with a sudden yawing motion. Further, the second state quantity Kos calculated based on the state quantity representing the speed of the yawing motion is read, and it can be determined whether this is greater than the predetermined value kos1. If it is determined that the vehicle is not in an abrupt oversteer state (when a negative determination (No) is made in step S310), the preliminary control is not started, and thus the preliminary control is not started. If an affirmative determination (Yes) is made in step S310, the arithmetic processing proceeds to step S320.

  In step S320, it is determined whether the vehicle speed Vx is greater than a predetermined value v1. If the vehicle speed Vx is equal to or less than the predetermined value v1 and a negative determination (No) is made in step S320, the preliminary control is not started. When the vehicle speed is low, a sudden yawing behavior does not occur, and the necessity for compensating the response of the brake actuator is low. If the vehicle speed Vx is greater than the predetermined value v1 and an affirmative determination (Yes) is made in step S320, the calculation process proceeds to step S330.

  In step S330, it is determined that the driver is not performing a braking operation. This determination is made based on a comparison result between the braking operation amount Bs and the predetermined value bs1. When the braking operation amount Bs is equal to or greater than the predetermined value bs1 and the braking operation member BP is operated, a negative determination (No) is made in step S330, and the preliminary control is not started. During the driver's braking operation, braking torque is already generated on the wheels, and no preliminary control is required. If Bs <bs1, and an affirmative determination (Yes) is made in step S330, the arithmetic processing proceeds to step S340.

  In step S340, it is determined whether the magnitude (absolute value) of the actual lateral acceleration Gya is greater than a predetermined value gy1. If the actual lateral acceleration Gya is equal to or less than the predetermined value gy1, and a negative determination (No) is made in step S340, the preliminary control is not started. When the actual lateral acceleration is low, a sudden yawing behavior does not occur, and the necessity for compensating the response of the brake actuator is low. If the magnitude (absolute value) of the actual lateral acceleration Gya is greater than the predetermined value gy1, and an affirmative determination (Yes) is made in step S340, the arithmetic processing proceeds to step S350.

  In step S350, it is determined whether the current steering operation is “second steering”. The “second steering” is a steering operation that is continuously performed in another direction (a direction opposite to the one direction) immediately after the steering operation is performed in one direction. The determination of whether or not it is “second steering” is made based on the steering direction Dstr. If the steering operation is the second steering and an affirmative determination (Yes) is made in step S350, the arithmetic processing proceeds to step S430. If a negative determination (No) is made in step S350, the calculation process proceeds to step S360.

  In step S360, it is determined whether the current steering operation is “cut-in” steering. “Incision” steering is a steering operation performed in a direction away from the neutral position of the steering device. The determination as to whether or not the turning steering is performed is made based on the steering angle Sa. In the case of infeed steering, the magnitude (absolute value) of the steering angle Sa increases. The steering operation is “switchback” steering (the steering operation is performed in a direction approaching the neutral position of the steering device, and the magnitude (absolute value) of the steering angle Sa is decreased). In step S360, a negative determination is made (No ), The calculation process proceeds to step S400. If the steering operation is “cut steering” and an affirmative determination (Yes) is made in step S360, the calculation process proceeds to step S370.

  In step S370, it is determined whether the magnitude (absolute value) of the steering angular velocity dSa is greater than a predetermined value dsa1. If the steering angular velocity dSa is equal to or less than the predetermined value dsa1 and a negative determination (No) is made in step S370, the preliminary control is not started. When the steering angular velocity dSa is small, a rapid yawing behavior does not occur, and the necessity for compensating the response of the brake actuator is low. If the magnitude (absolute value) of the steering angular velocity dSa is greater than the predetermined value dsa1, and an affirmative determination (Yes) is made in step S370, the arithmetic processing proceeds to step S380.

  In step S380, it is determined whether the magnitude (absolute value) of the yaw angular acceleration dYr is greater than a predetermined value dyr1. If the yaw angular acceleration dYr is equal to or smaller than the predetermined value dyr1 and a negative determination (No) is made in step S380, the preliminary control is not started. When the yaw angular acceleration dYr is small, no rapid yawing behavior has occurred. If the magnitude (absolute value) of the yaw angular acceleration dYr is larger than the predetermined value dyr1 and an affirmative determination (Yes) is made in step S380, the arithmetic processing proceeds to step S390, and preliminary control is started. In step S390, the preset predetermined value pre1 is output as the preliminary control target value Qpt **.

  When the steering operation is the first steering switchback state (when the magnitude of the steering angle Sa decreases based on the steering angle Sa), the calculation process proceeds from step S360 to step S400.

  In step S400, it is determined whether the magnitude (absolute value) of the steering angular velocity dSa is greater than a predetermined value dsa2. If the steering angular velocity dSa is equal to or less than the predetermined value dsa2 and a negative determination (No) is made in step S400, the preliminary control is not started. When the steering angular velocity dSa is small, a rapid yawing behavior does not occur, and the necessity for compensating the response of the brake actuator is low. If the magnitude (absolute value) of the steering angular velocity dSa is larger than the predetermined value dsa2, and an affirmative determination (Yes) is made in step S400, the arithmetic processing proceeds to step S410.

  In step S410, it is determined whether the magnitude (absolute value) of the yaw angular acceleration dYr is greater than a predetermined value dyr2. If the yaw angular acceleration dYr is equal to or less than the predetermined value dyr2, and a negative determination (No) is made in step S410, the preliminary control is not started. When the yaw angular acceleration dYr is small, no rapid yawing behavior has occurred. If the magnitude (absolute value) of the yaw angular acceleration dYr is greater than the predetermined value dyr2, and an affirmative determination (Yes) is made in step S410, the arithmetic processing proceeds to step S420.

  In step S420, it is determined whether the magnitude (absolute value) of the steering angle Sa is smaller than a predetermined value sa1. If the steering angle Sa is equal to or greater than the predetermined value sa1 and a negative determination (No) is made in step S420, the preliminary control is not started. If an affirmative determination (Yes) is made in step S420, the calculation process proceeds to step S390, and preliminary control is started. In step S390, a preset predetermined value pre2 is output as the preliminary control target value Qpt **.

  When the steering operation is the second steering (when the steering direction continuously changes from one direction to the other based on the steering direction Dstr), the calculation process proceeds from step S350 to step S430.

  In step S430, it is determined whether the magnitude (absolute value) of the steering angular velocity dSa is greater than a predetermined value dsa3. If the steering angular velocity dSa is equal to or less than the predetermined value dsa3 and a negative determination (No) is made in step S430, the preliminary control is not started. When the steering angular velocity dSa is small, a rapid yawing behavior does not occur, and the necessity for compensating the response of the brake actuator is low. If the magnitude (absolute value) of the steering angular velocity dSa is greater than the predetermined value dsa3 and an affirmative determination (Yes) is made in step S430, the arithmetic processing proceeds to step S440.

  In step S440, it is determined whether the magnitude (absolute value) of the yaw angular acceleration dYr is greater than a predetermined value dyr3. If the yaw angular acceleration dYr is equal to or less than the predetermined value dyr3 and a negative determination (No) is made in step S440, the preliminary control is not started. When the yaw angular acceleration dYr is small, no rapid yawing behavior has occurred. If the magnitude (absolute value) of the yaw angular acceleration dYr is greater than the predetermined value dyr3 and an affirmative determination (Yes) is made in step S440, the arithmetic processing proceeds to step S450.

  In step S450, it is determined whether the magnitude (absolute value) of the steering angle Sa is smaller than a predetermined value sa2. If the steering angle Sa is equal to or greater than the predetermined value sa2 and a negative determination (No) is made in step S450, the preliminary control is not started. If an affirmative determination (Yes) is made in step S450, the calculation process proceeds to step S390, and preliminary control is started. In step S390, a preset predetermined value pre3 is output as the preliminary control target value Qpt **.

  The predetermined values (positive values) v1, bs1, gy1, dsa1, dsa2, dsa3, dyr1, dyr2, dyr3, sa1, sa2 are threshold values for determining the start of the preliminary control (determining the start of the preliminary control). Threshold). The predetermined values dsa1, dsa2, and dsa3 correspond to the first predetermined value, the predetermined value sa1 to the second predetermined value, the predetermined value sa2 to the third predetermined value, and the predetermined values dyr1, dyr2, and dyr3 to the fourth predetermined value, respectively. The determination block does not need to include all of them, and any one or more of them can be omitted.

  With reference to FIG. 9, the preliminary control end determination step S220 in FIG. 7 (corresponding to the end determination calculation block of the preliminary control calculation block B60 in FIG. 6) will be described. The completion determination of the preliminary control is performed for each wheel.

  In step S510, the time during which the preliminary control is started and continued (duration Tpc) is counted. In step S520, it is determined whether the vehicle speed Vx is less than a predetermined value v2 (<v1). If the vehicle speed Vx is less than the predetermined value v2 and an affirmative determination (Yes) is made in step S520, the calculation process proceeds to step S580. In step S580, the preliminary control is terminated and the preliminary control target value Qpt ** is set to “0”. This is because if the vehicle speed decreases, a sudden yawing behavior does not occur. If the vehicle speed Vx is equal to or higher than the predetermined value v2 and a negative determination (No) is made in step S520, the calculation process proceeds to step S530.

  In step S530, it is determined based on the braking operation amount Bs whether the driver has started the braking operation after the start of the preliminary control. When the driver's braking operation is started, Bs> bs2 (> bs1), and when an affirmative determination (Yes) is made in step S530, the calculation process proceeds to step S580. If the braking operation amount Bs is equal to or less than the predetermined value bs2, and a negative determination (No) is made in step S530, the calculation process proceeds to step S540.

  In step S540, it is determined whether the magnitude of the steering angular velocity dSa is less than a predetermined value dsa4 (<dsa1, dsa2, dsa3). If the magnitude of the steering angular velocity dSa is less than the predetermined value dsa4 and an affirmative determination (Yes) is made in step S540, the arithmetic processing proceeds to step S580. In step S580, the preliminary control is terminated. This is because if the steering angular velocity is reduced, a sudden yawing behavior does not occur. If the magnitude of the steering angular velocity dSa is equal to or greater than the predetermined value dsa4 and a negative determination (No) is made in step S540, the calculation process proceeds to step S550.

  In step S550, it is determined whether the magnitude of the yaw angular acceleration dYr is less than a predetermined value dyr4 (<dyr1, dyr2, dyr3). If the magnitude of the yaw angular acceleration dYr is less than the predetermined value dyr4 and no rapid yawing behavior has already occurred, an affirmative determination (Yes) is made in step S550, and the calculation process proceeds to step S580. If the magnitude of the yaw angular acceleration dYr is equal to or greater than the predetermined value dyr4 and a negative determination (No) is made in step S550, the calculation process proceeds to step S560.

  In step S560, it is determined whether the magnitude of the actual lateral acceleration Gya is less than a predetermined value gy2 (<gy1). The magnitude of the actual lateral acceleration Gya is less than the predetermined value gy2, an affirmative determination (Yes) is made in step S560, and the arithmetic processing proceeds to step S580. If the magnitude of the actual lateral acceleration Gya is greater than or equal to the predetermined value gy2, and a negative determination (No) is made in step S560, the arithmetic processing proceeds to step S570.

  In step S570, it is determined whether the duration Tpc of the preliminary control is greater than a predetermined value tkz1. The continuation time Tpc is greater than the predetermined value tkz1, an affirmative determination (Yes) is made in step S570, the calculation process proceeds to step S580, and the preliminary control is terminated. After a predetermined time has passed since the sudden steering operation was performed, the vehicle stability control is not started and no preliminary control is required. If the duration time Tpc is equal to or less than the predetermined value tkz1 and a negative determination (No) is made in step S570, the preliminary control is continued.

  The predetermined values (positive values) v2, bs2, gy2, dsa4, dyr4, tkz1 are threshold values for determining the end of the preliminary control (preliminary control end determination threshold value). The determination block does not need to include all of them, and any one or more of them can be omitted.

  The operation and effect of the above-described embodiment of the present invention will be described with reference to FIGS. When the preliminary control is executed, the driver may feel uncomfortable due to the driving sound of the actuator or the like or the slight deceleration of the vehicle by the preliminary control. The case where the preliminary control is required is an oversteer case in which a rapid yawing behavior occurs. Therefore, when the steering angular velocity dSa is large and the start of vehicle stability control (main control) is predicted, the state quantity (second state) different from the state quantity (first state quantity Jos) used for execution of the main control is predicted. Based on the quantity Kos), an oversteer tendency with a sudden change in yawing movement is determined. The first state quantity Jos is a state quantity that represents the magnitude of the yawing motion (a state quantity including the actual (vehicle body) side slip angle βa of the vehicle, and is at least one of the side slip angle deviation Δβ and the actual side slip angle βa. A value calculated based on one of them) and a state quantity (the actual quantity including the actual yaw rate Yra) indicating the speed of the yawing motion, and at least one of yaw rate deviation ΔYr and sideslip angular velocity dβa. The value is calculated based on the mutual relationship with the value calculated based on Accordingly, the calculation of the first state quantity Jos includes a side slip angle term, and a relatively moderate oversteer tendency can be identified. On the other hand, the second state quantity Kos is calculated based on the state quantity representing the speed of the yawing motion. Therefore, since the calculation of the second state quantity Kos does not include the side slip angle term but only the yaw rate term, an oversteer tendency of yawing behavior that is relatively faster than the identification by the first state quantity Jos can be identified. By the second state quantity Kos, a rapid increase in oversteer tendency is determined at an early stage, and the execution of the preliminary control can be started quickly. The predetermined values dsa1, dsa2, and dsa3 correspond to the first predetermined value, the predetermined value sa1 corresponds to the second predetermined value, the predetermined value sa2 corresponds to the third predetermined value, and the predetermined values dyr1, dyr2, and dyr3 correspond to the fourth predetermined value, respectively. .

  First, with reference to FIG. 10, the operation and effect in the case of J-turn steering will be described. At time u0, a sudden steering operation is started in one direction (left direction), and the steering angle Sa is rapidly increased. The steering angular velocity dSa is acquired, and the magnitude (absolute value) of the steering angular velocity dSa is compared with a predetermined value dsa1. The steering angular velocity dSa can be calculated based on the steering angle Sa. A control flag Fdsa representing the comparison result can be provided. As the control flag Fdsa, “0” is output when the steering angular velocity dSa is equal to or less than the predetermined value dsa1, and “1” is output when the steering angular velocity dSa is greater than the predetermined value dsa1. At time u1, the condition of dSa> dsa1 is satisfied.

  The second state quantity Kos and the predetermined value kos1 are compared, and a second control flag Fk as a comparison result is output. As the second control flag Fk, “0” is output when the second state quantity Kos is equal to or smaller than the predetermined value kos1, and “1” is output when the second state quantity Kos is larger than the predetermined value kos1. At time u2, the condition of Kos> kos1 is satisfied and an oversteer tendency with a sudden yawing movement is identified. When the conditions of dSa> dsa1 (Fdsa = 1) and Kos> kos1 (Fk = 1) are satisfied (time u2), the preliminary control is started. Preliminary control target value Qptfr (= final target value Pwtfr = predetermined value pre1) is output for the outer front wheel of the turn, and the actual braking torque Pwafr is increased.

  At time u4, the main control of the vehicle stability control based on the first state quantity Jos is started. Although the main control needs to cope with a gradual oversteer tendency, it is sufficient that the preliminary control can cope only with an oversteer tendency accompanied by a fast yawing motion. Therefore, preliminary control can be started early by identifying an oversteer tendency accompanied by a fast yawing motion based on the second state quantity Kos different from the first state quantity Jos.

  The yaw angular acceleration dYr is acquired, and the magnitude of the yaw angular acceleration dYr corresponding to the steering angular velocity dSa can be compared with the predetermined value dyr1. “The magnitude of the yaw angular acceleration dYr corresponding to the steering angular velocity dSa” means the absolute value of the yaw angular acceleration dYr when the signs of the steering angular velocity dSa and the yaw angular acceleration dYr match. Here, the yaw angular acceleration dYr can be calculated based on the yaw rate Yra. A control flag Fdyr representing the comparison result can be provided. As the control flag Fdyr, “0” is output when the yaw angular acceleration dYr is equal to or less than the predetermined value dyr1, and “1” is output when the yaw angular acceleration dYr is greater than the predetermined value dyr1. When at least the conditions of Fdsa = 1, Fk = 1, and dYr> dyr1 (Fdyr = 1) are satisfied (time u3), the preliminary control can be started. When the vehicle exhibits an understeer tendency, the yaw angular acceleration dYr does not become so large. By considering the yaw angular acceleration dYr at the start of the preliminary control, a more reliable preliminary control can be executed.

  The actual lateral acceleration Gya is acquired, and the magnitude of the actual lateral acceleration Gya can be compared with a predetermined value gy1. A control flag Fgy (not shown) representing the comparison result can be provided. As the control flag Fgy, “0” is output when the actual lateral acceleration Gya is equal to or less than the predetermined value gy1, and “1” is output when the actual lateral acceleration Gya is greater than the predetermined value gy1. When at least the conditions of Fdsa = 1, Fk = 1, and Gya> gy1 (Fgy = 1) are satisfied, the preliminary control is started. Since the rapid yawing behavior occurs when the friction coefficient of the road surface is relatively high, more reliable preliminary control can be performed by adding the condition of the lateral acceleration to the start determination of the preliminary control.

  Next, operations and effects in the case of lane change steering (transient steering) will be described with reference to FIG. The vehicle is steered suddenly in the left direction at time v0, and is continuously steered in the right direction at time v6. Hereinafter, the determination at the time of turning back the first steering is mainly shown, and the determination at the time of turning the second steering is shown in [] (square brackets).

  First, the steering angular velocity dSa is acquired, and the magnitude of the steering angular velocity dSa is compared with a predetermined value dsa2 [predetermined value dsa3]. As described above, the steering angular velocity dSa can be calculated based on the steering angle Sa. A control flag Fdsa representing the comparison result can be provided. As the control flag Fdsa, “0” is output when the steering angular velocity dSa is equal to or less than the predetermined value dsa2 [predetermined value dsa3], and “1” is output when the steering angular velocity dSa is greater than the predetermined value dsa2 [predetermined value dsa3]. The At time v3 [time v6], the condition of dSa> dsa2 [dsa3] is satisfied.

  The second state quantity Kos is calculated and compared with a predetermined value kos1. A second control flag Fk, which is the comparison result, is output. As the second control flag Fk, “0” is output when the second state quantity Kos is equal to or smaller than the predetermined value kos1, and “1” is output when the second state quantity Kos is larger than the predetermined value kos1. At time v2, the condition of Kos> kos1 is satisfied and an oversteer tendency with a sudden yawing movement is identified. When the condition of dSa> dsa2 [dsa3] (Fdsa = 1) and Kos> kos1 (Fk = 1) is satisfied (time v3 [time v6]), the preliminary control is started. Preliminary control target value Qptfl (= final target value Pwtfl = predetermined value pre2 [predetermined value pre3]) is output to the front wheels that are outside in the turning state corresponding to the second steering, and the actual braking torque Pwafl is increased. Is done. Based on the first state quantity Jos, the oversteer behavior with rapid yawing change is determined earlier than the start of the main control of the vehicle stability control (for example, at time v7). Therefore, since the preliminary control is started earlier, the response of the brake actuator BRK can be effectively compensated.

  The yaw angular acceleration dYr is acquired, and the magnitude (absolute value) of the yaw angular acceleration dYr corresponding to the steering angular velocity dSa can be compared with the predetermined value dyr2 [predetermined value dyr3]. As described above, “the magnitude of the yaw angular acceleration dYr corresponding to the steering angular velocity dSa” means the absolute value of the yaw angular acceleration dYr when the signs of the steering angular velocity dSa and the yaw angular acceleration dYr match. The yaw angular acceleration dYr can be calculated based on the yaw rate Yra. A control flag Fdyr representing the comparison result can be provided. As the control flag Fdyr, “0” is output when the yaw angular acceleration dYr is equal to or smaller than the predetermined value dyr2 [predetermined value dyr3], and “1” is larger when the yaw angular acceleration dYr is larger than the predetermined value dyr2 [predetermined value dyr3]. Is output. When at least the conditions of Fdsa = 1, Fk = 1, and dYr> dyr2 [dyr3] (Fdyr = 1) are satisfied, the preliminary control can be started. More appropriate because it is determined that a sudden change in yawing behavior (yaw angular acceleration) appears in the same direction as the steering operation (the directions of the steering angular velocity dSa and the yaw angular acceleration dYr coincide), and preliminary control is started. Preliminary control can be performed.

  The steering angle Sa is acquired, and the magnitude (absolute value) of the steering angle Sa can be compared with a predetermined value sa1 [predetermined value sa2]. A control flag Fsa representing the comparison result can be provided. As the control flag Fsa, “0” is output when the steering angle Sa is equal to or larger than the predetermined value sa1 [predetermined value sa2], and “1” is output when the steering angle Sa is smaller than the predetermined value sa1 [predetermined value sa2]. The When at least the conditions of Fdsa = 1, Fk = 1, and Sa> sa1 [sa2] (Fsa = 1) are satisfied, the preliminary control can be started. When the second steering is not performed after the first steering is performed, there is a low possibility that a sudden yawing behavior will occur. Therefore, the magnitude of the steering angle is added to the start condition of the preliminary control, and the preliminary control is started when the execution of the second steering is reliably predicted or immediately after the second steering is started.

  The actual lateral acceleration Gya is acquired, and the magnitude (absolute value) of the actual lateral acceleration Gya can be compared with the predetermined value gy1. A control flag Fgy (not shown) representing the comparison result can be provided. As the control flag Fgy, “0” is output when the actual lateral acceleration Gya is equal to or less than the predetermined value gy1, and “1” is output when the actual lateral acceleration Gya is greater than the predetermined value gy1. When at least the conditions of Fdsa = 1, Fk = 1, and Gya> gy1 (Fgy = 1) are satisfied, the preliminary control can be started. Similar to J-turn steering, a sudden yawing behavior occurs when the road friction coefficient is relatively high. Therefore, a more reliable preliminary control can be performed by adding the condition of the lateral acceleration to the start determination of the preliminary control.

  Here, at least one set of the predetermined values dsa2 and dsa3, the predetermined values dyr2 and dyr3, and the predetermined values sa1 and sa2 may be the same value.

The predetermined values dyr1, dyr2, and dyr3 are preliminary control start threshold values for the yaw angular acceleration dYr, and at least one of them may be set based on the actual lateral acceleration Gya. As shown in FIG. 12, at least one of the predetermined values dyr1, dyr2, and dyr3 is a characteristic that is the predetermined value y1 in the range where the actual lateral acceleration Gya is not less than “0” and less than the predetermined value g1, In the range where the acceleration Gya is greater than or equal to the predetermined value g1 and less than the predetermined value g2 (> g1), the characteristic increases as the actual lateral acceleration Gya increases, and when the actual lateral acceleration Gya is greater than or equal to the predetermined value g2 > Y1) is set based on a calculation map constituted by characteristics. The actual lateral acceleration Gya reflects the friction coefficient of the road surface. Based on the actual lateral acceleration Gya, at least one of the predetermined values dyr1, dyr2, and dyr3 is set, so that it corresponds to the road surface condition. Preliminary control can be performed.
The technical idea that can be grasped from the above embodiment will be added below.
(1)
Braking means for applying braking torque to the wheels of the vehicle, actual turning state amount acquisition means for acquiring the actual turning state amount of the vehicle, and calculating the first state amount based on the actual turning state amount; First discriminating means for discriminating whether or not the vehicle has an oversteer tendency based on one state quantity, and controlling the braking torque via the braking means based on an identification result of the first discriminating means. In the vehicle motion control device for maintaining the running stability of the vehicle,
Second identification means for calculating a second state quantity different from the first state quantity based on the actual turning state quantity and identifying whether the vehicle is oversteered based on the second state quantity. When,
Steering angular velocity acquisition means for acquiring the steering angular velocity of the vehicle;
Control means for controlling the braking torque based on the identification result of the second identification means and the steering angular velocity;
A vehicle motion control device comprising:
The vehicle motion control apparatus according to the present invention includes a braking unit B10 that applies braking torque to the wheels of the vehicle, and an actual turning state amount acquisition unit B20 that acquires an actual turning state amount (Yra, Gya, etc.) that acts on the vehicle. The first state quantity Jos is calculated based on the actual turning state quantity, and the first identifying means B30 for identifying the oversteer tendency of the vehicle based on the first state quantity Jos. Further, the present device calculates a second state quantity Kos different from the first state quantity Jos based on the actual turning state quantity (Yra, Gya, etc.) of the vehicle, and oversteering the vehicle based on the second state quantity Kos. Second identifying means B40 for identifying a tendency, steering angular speed obtaining means B50 for obtaining the steering angular speed dSa of the vehicle, and control means B60 for controlling the braking torque of the wheels by controlling the braking means B10. The control unit B60 controls the braking torque of the wheels via the braking unit B10 based on the identification results Fj and Jos of the first identification unit B30, and executes vehicle stability control that maintains the stability of the vehicle. Further, the control unit B60 controls the braking unit B10 based on the identification result Fk of the second identification unit B40 and the steering angular velocity dSa, and applies the braking torque that improves the responsiveness of the vehicle stability control.
(2)
In the vehicle motion control device according to (1),
The control means includes
The vehicle motion control device according to claim 1, wherein the braking torque is applied when the steering angular velocity is greater than a first predetermined value and the identification result of the second identification means is a result of affirming an oversteer tendency.
Here, in the control means B60, the steering angular velocity dSa (absolute value thereof) is larger than the first predetermined value (predetermined values dsa1, dsa2, dsa3 described above), and the identification result Fk of the second identification means B40 tends to oversteer. When shown (Fk = 1), braking torque can be applied to the wheels.
(3)
In the vehicle motion control apparatus according to (1) or (2),
The second identification means includes
The vehicle motion control apparatus for identifying a yawing motion of the vehicle that is relatively faster than the first identification means.
The second discriminating means B40 discriminates a relatively fast vehicle yawing movement compared to the first discriminating means B30.
(4)
In the vehicle motion control device according to any one of (1) to (3),
The first identification means includes
Calculating the first state quantity based on the correlation between the state quantity representing the magnitude of the yawing movement of the vehicle and the state quantity representing the speed of the yawing movement of the vehicle;
The second identification means includes
A vehicle motion control apparatus that calculates the second state quantity based only on a state quantity representing the speed of yawing motion of the vehicle.
The first discriminating means B30 is a state quantity indicating the magnitude of the yawing motion of the vehicle (for example, a skid angle βa, a side slip angle deviation Δβ) and a state quantity indicating the speed of the yawing motion of the vehicle (for example, the skid angular velocity dβa, yaw rate). The first (oversteer) state quantity Jos is calculated based on the correlation with the deviation ΔYr). In addition, the second identification unit B40 is configured to calculate the second (oversteer) state quantity Kos based only on the state quantity (for example, the side-slip angular velocity dβa, the yaw rate deviation ΔYr) representing the speed of the yawing motion of the vehicle. Has been.
(5)
The vehicle motion control device according to any one of (1) to (4),
Steering angle acquisition means for acquiring the steering angle of the vehicle,
The control means includes
The vehicle motion control device according to claim 1, wherein the braking torque is applied when the steering angle decreases and the steering angle is smaller than a second predetermined value.
The vehicle motion control apparatus according to the present invention includes steering angle acquisition means B70 for acquiring the steering angle Sa of the vehicle. The control means B60 can apply the braking torque when the steering angle Sa (the absolute value thereof) decreases and the steering angle Sa (the absolute value thereof) is smaller than the second predetermined value (the predetermined value sa1 described above). . The steering angular velocity acquisition unit B50 can calculate the steering angular velocity dSa based on the steering angle Sa acquired by the steering angle acquisition unit B70.
(6)
The vehicle motion control device according to any one of (1) to (5),
Steering angle acquisition means for acquiring the steering angle of the vehicle;
Steering direction determination means for determining whether the steering direction of the vehicle is one direction or the other direction based on the steering angle;
The control means includes
When the steering direction is determined to be the other direction continuously after the steering direction is determined to be the one direction by the steering direction determination means, the steering angle is increased, and the steering angle is smaller than a third predetermined value A vehicle motion control device characterized by applying the braking torque to the vehicle.
In the vehicle motion control apparatus according to the present invention, based on the steering angle Sa acquired by the steering angle acquisition means B70, the vehicle steering direction Dstr is one direction or the other direction (opposite of the one direction). Steering direction determination means B80 for determining whether the direction is a direction). The control means B60 determines that the steering direction Dstr is continuously one direction after the steering direction determination means B80 determines that the steering direction Dstr is one direction, the steering angle Sa (absolute value) increases, and the steering angle Sa ( The braking torque can be applied when the absolute value is smaller than the third predetermined value (the above-described predetermined value sa2).
(7)
The vehicle motion control device according to any one of (1) to (6),
A yaw angular acceleration acquisition means for calculating a yaw angular acceleration based on the actual turning state quantity;
The control means includes
The vehicle motion control device, wherein the braking torque is applied when the yaw angular acceleration is greater than a fourth predetermined value.
The vehicle motion control apparatus according to the present invention includes yaw angular acceleration calculation means B90 for obtaining the yaw angular acceleration dYr of the vehicle. The yaw angular acceleration dYr can be calculated based on the actual turning state amount (yaw rate Yra) acquired by the actual turning state amount acquisition unit B20. The control unit B60 can apply the braking torque of the wheel when the yaw angular acceleration dYr (absolute value thereof) is larger than the fourth predetermined value (the predetermined values dyr1, dyr2, dyr3 described above).

  BRK ... Brake actuator, ECU ... Electronic control unit, GY ... Lateral acceleration sensor, WS ** ... Wheel speed sensor, YR ... Yaw rate sensor

Claims (1)

The vehicle includes a braking unit that applies braking torque to the wheels of the vehicle, and executes vehicle stability control that maintains the running stability of the vehicle by controlling the braking unit.
In the vehicle stability control, the vehicle stability control includes a main control that suppresses an oversteer tendency of the vehicle, and a preliminary control that operates in advance of the main control and compensates for the response of the braking means. ,
An actual turning state amount acquisition means for acquiring an actual turning state amount of the vehicle;
First identification means for calculating a first state quantity based on the actual turning state quantity and identifying whether the vehicle is in an oversteer tendency based on the first state quantity;
A motion control apparatus for vehicles that control the braking torque of the main control over the braking means based on the identification result of the first identification means,
A second state quantity different from the first state quantity is calculated based on the actual turning state quantity, and it is determined whether the vehicle is oversteered based on the second state quantity, and the first compared to the identification means, and a second identification means for identifying the yawing motion of relatively fast the vehicle,
Steering angular velocity acquisition means for acquiring the steering angular velocity of the vehicle;
A vehicle motion control device comprising: control means for controlling the braking torque of the preliminary control based on the identification result of the second identification means and the steering angular velocity.

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