JP5859510B2 - Vehicle behavior control device - Google Patents

Description

  The present invention relates to a vehicle behavior control device that stabilizes the behavior of a vehicle.

  2. Description of the Related Art There is known a vehicle behavior control device that stabilizes the behavior of a vehicle by applying braking force to some wheels when the vehicle becomes unstable due to sudden steering or the like. The conventional vehicle behavior control device acquires an actual turning state amount of the vehicle such as an actual yaw rate, and applies braking force to some wheels when the vehicle becomes unstable based on the turning state amount. The behavior of the vehicle is stabilized.

  In such an apparatus, in order to minimize the disturbance of the behavior of the vehicle, it is desirable to start the control as soon as possible when the disturbance of the behavior of the vehicle can be predicted. For example, in Patent Document 1, after turning the steering to one of the left and right, the threshold for starting the behavior stabilization control is changed when the steering is turned back to the opposite side.

JP 2010-64720 A

  By the way, it takes some time until the behavior of the vehicle appears after the steering operation. Therefore, when the disturbance of the behavior of the vehicle is predicted based on the actual amount of turning state of the vehicle as in the device of Patent Document 1, the start of the control is not sufficiently fast. Further, in the apparatus of Patent Document 1, since the threshold value is changed on the condition that it is a reverse steering, the threshold value is not changed even when the steering at the first turning is sudden, and as a result, the control There is a problem that the start is slow.

  Therefore, an object of the present invention is to provide a vehicle behavior control device capable of appropriately predicting a disturbance in the behavior of the vehicle and starting control for stabilizing the behavior of the vehicle at an early stage.

  The present invention that solves the above-described problems includes a steering angle acquisition unit that acquires a steering angle, a steering angular velocity acquisition unit that acquires a steering angular velocity, a vehicle speed acquisition unit that acquires a vehicle speed, the vehicle speed and the steering angle, A reference yaw rate calculating means for calculating a reference yaw rate of the vehicle based on the vehicle, a limit yaw rate setting means for setting a limit yaw rate that is a limit yaw rate at which the vehicle can stably travel based on the vehicle speed, and a turning outer wheel of the vehicle And a behavior stabilization control means for performing a behavior stabilization control for stabilizing the behavior of the vehicle by applying a braking force with a set target braking force, the behavior stabilization control means for adjusting the limit yaw rate and the steering angular velocity. And a control intervention threshold setting unit for setting a control intervention threshold, and the behavior stabilization when the reference yaw rate exceeds the control intervention threshold. And having a determining control intervention determination unit to start the control.

  According to such a configuration, it is possible to determine the start of behavior stabilization control based on the steering angle, the steering angular velocity, and the vehicle speed without being based on the actual yaw rate. It can be determined that the behavior stabilization control starts before appearing, and the behavior stabilization control can be started early.

  In the above-described apparatus, the control intervention threshold value setting unit can set the absolute value of the control intervention threshold value smaller as the absolute value of the steering angular velocity is larger.

  According to such a configuration, the absolute value of the control intervention threshold decreases as the absolute value of the steering angular velocity increases, so that the behavior stabilization control can be started at the initial stage of sudden steering from the straight traveling state.

  In the above-described apparatus, it is desirable that the behavior stabilization control unit increases the target braking force as the deviation between the reference yaw rate and the limit yaw rate is larger.

  According to such a configuration, since the braking force according to the predicted magnitude of the disturbance of the vehicle behavior can be applied to the turning outer wheel, the disturbance of the behavior of the vehicle can be reduced.

  In the above-described apparatus, the behavior stabilization control unit includes a control end determination unit that determines to end the behavior stabilization control when the absolute value of the reference yaw rate falls below a control end threshold, and sets the control end threshold to Based on the vehicle speed, the larger the vehicle speed, the smaller the value can be set.

  According to the vehicle behavior control device of the present invention, it is possible to appropriately predict a disturbance in the behavior of the vehicle and start behavior stabilization control at an early stage.

It is a lineblock diagram of vehicles provided with a vehicle behavior control device concerning one embodiment of the present invention. It is a block diagram which shows the structure of a hydraulic unit. It is a block diagram which shows the structure of a control part. 6 is a timing chart showing changes in steering angular velocity, deviation, corrected deviation, and output coefficient. It is a map which shows the relationship between steering angular velocity and offset amount. It is a map which shows the relationship between the deviation of the standard yaw rate and the limit yaw rate, and the target hydraulic pressure for setting the target hydraulic pressure. For setting the present target pressure PT _n at the end processing mode, a map showing the current relationship between the target fluid pressure PT _n preceding the target hydraulic pressure PT _n-1. It is a flowchart which shows the whole process of behavior stabilization control. It is a flowchart which shows the whole process of target hydraulic pressure setting. It is a flowchart which shows the setting process of an output coefficient. It is a flowchart which shows the process of control end determination. It is a timing chart which shows change of vehicle speed, various yaw rates, and steering angular velocity for explaining operation of vehicle behavior control. 6 is a timing chart showing (a) changes in steering angle, actual yaw rate and slip angle, and (b) changes in brake fluid pressure of each wheel in a conventional vehicle behavior control device. 4 is a timing chart showing (a) changes in steering angle, actual yaw rate, and slip angle, and (b) changes in brake hydraulic pressure of each wheel in the vehicle behavior control device of the present embodiment. 5 is a timing chart showing (a) change in steering angle and actual yaw rate, and (b) change in brake fluid pressure of the left wheel in a vehicle behavior control device of a comparative example. 4 is a timing chart showing (a) change in steering angle and actual yaw rate, (b) change in brake fluid pressure of the left wheel, and (c) change in output coefficient in the vehicle behavior control device of the present embodiment.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the vehicle behavior control device A according to an embodiment is a device that appropriately controls the braking force applied to each wheel W of the vehicle CR. The vehicle behavior control apparatus A mainly includes a hydraulic unit 10 provided with an oil passage and various components, and a control unit 100 for appropriately controlling various components in the hydraulic unit 10.

  Each wheel W is provided with a wheel brake FL, RR, RL, FR, and each wheel brake FL, RR, RL, FR is braked by a hydraulic pressure supplied from a master cylinder MC as a hydraulic pressure source. Is provided. Master cylinder MC and wheel cylinder H are each connected to hydraulic unit 10. Then, the brake fluid pressure generated in the master cylinder MC according to the depression force of the brake pedal BP (driver's braking operation) is supplied to the wheel cylinder H after being controlled by the control unit 100 and the fluid pressure unit 10.

  Connected to the controller 100 are a pressure sensor 91 that detects the pressure of the master cylinder MC, a wheel speed sensor 92 that detects the wheel speed of each wheel W, and a steering angle sensor 93 that detects the steering angle θ of the steering ST. ing. The control unit 100 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output circuit, and inputs from the sensors 91 to 93 and the ROM The control is executed by performing various arithmetic processes based on the programs and data stored in. Details of the control unit 100 will be described later.

  As shown in FIG. 2, the hydraulic unit 10 includes a master cylinder MC that is a hydraulic pressure source that generates a brake hydraulic pressure corresponding to a pedaling force applied by the driver to the brake pedal BP, and wheel brakes FR, FL, RR, RL. It is arranged between. The hydraulic unit 10 includes a pump body 10a which is a base body having an oil passage (hydraulic passage) through which brake fluid flows, a plurality of inlet valves 1, outlet valves 2 and the like arranged on the oil passage. The two output ports M1, M2 of the master cylinder MC are connected to the inlet port 121 of the pump body 10a, and the outlet port 122 of the pump body 10a is connected to each wheel brake FL, RR, RL, FR. In normal times, the oil passage is communicated from the inlet port 121 to the outlet port 122 in the pump body 10a, so that the depression force of the brake pedal BP is transmitted to the wheel brakes FL, RR, RL, FR. It is like that.

  Here, the oil path starting from the output port M1 leads to the wheel brake FL on the left side of the front wheel and the wheel brake RR on the right side of the rear wheel, and the oil path starting from the output port M2 is set to the wheel brake FR on the right side of the front wheel and the left side of the rear wheel. To the wheel brake RL. Hereinafter, the oil passage starting from the output port M1 is referred to as “first system”, and the oil passage starting from the output port M2 is referred to as “second system”.

  The hydraulic unit 10 is provided with two control valve means VL corresponding to each wheel brake FL, RR in the first system, and similarly corresponding to each wheel brake RL, FR in the second system. Two control valve means VL are provided. The hydraulic unit 10 is provided with a reservoir 3, a pump 4, an orifice 5a, a pressure regulating valve (regulator) R, and a suction valve 7 in each of the first system and the second system. The hydraulic unit 10 is provided with a common motor 9 for driving the first system pump 4 and the second system pump 4.

  In the following, the oil passages from the output ports M1 and M2 of the master cylinder MC to the respective pressure regulating valves R are referred to as “output hydraulic pressure passages A1”, and the oil from the first system pressure regulating valve R to the wheel brakes FL and RR. The oil passages from the road and the second system pressure regulating valve R to the wheel brakes RL and FR are respectively referred to as “wheel hydraulic pressure passage B”. In addition, an oil path from the output hydraulic pressure path A1 to the pump 4 is referred to as “suction hydraulic pressure path C”, an oil path from the pump 4 to the wheel hydraulic pressure path B is referred to as “discharge hydraulic pressure path D”, and The oil passage from the wheel fluid pressure passage B to the suction fluid pressure passage C is referred to as “open passage E”.

  The control valve means VL is a valve that controls the flow of hydraulic pressure from the master cylinder MC or the pump 4 side to the wheel brakes FL, RR, RL, FR side (specifically, the wheel cylinder H side). (Pressure in the wheel cylinder H) can be increased, held or decreased. Therefore, the control valve means VL includes an inlet valve 1, an outlet valve 2, and a check valve 1a.

  The inlet valve 1 is a normally open electromagnetic valve provided between each wheel brake FL, RR, RL, FR and the master cylinder MC, that is, in the wheel hydraulic pressure path B. The inlet valve 1 is normally opened to allow the brake hydraulic pressure to be transmitted from the master cylinder MC to the wheel brakes FL, FR, RL, RR. In addition, the inlet valve 1 is appropriately closed by the control unit 100 to cut off the brake hydraulic pressure transmitted from the brake pedal BP to each wheel brake FL, FR, RL, RR.

  The outlet valve 2 is a normally closed electromagnetic valve interposed between each wheel brake FL, RR, RL, FR and each reservoir 3, that is, between the wheel hydraulic pressure path B and the release path E. Although the outlet valve 2 is normally closed, the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is released to each reservoir 3 by being appropriately opened by the control unit 100.

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a valve that only allows the brake fluid to flow from each wheel brake FL, FR, RL, RR side to the master cylinder MC side, and when the input from the brake pedal BP is released, Even when the valve 1 is closed, inflow of brake fluid from each wheel brake FL, FR, RL, RR side to the master cylinder MC side is allowed.

  The reservoir 3 is provided in the release path E, and has a function of storing brake fluid pressure that is released when each outlet valve 2 is opened. Further, between the reservoir 3 and the pump 4, a check valve 3a that allows only the flow of brake fluid from the reservoir 3 side to the pump 4 side is interposed.

  The pump 4 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A1 and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and sucks the brake fluid stored in the reservoir 3 And has a function of discharging to the discharge hydraulic pressure path D.

  The orifice 5a attenuates the pulsation of the pressure of the brake fluid discharged from the pump 4 and the pulsation generated when the pressure regulating valve R described later operates.

  The pressure regulating valve R permits the flow of brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B during normal times, and increases the pressure on the wheel cylinder H side by the brake hydraulic pressure generated by the pump 4. It has a function of adjusting the pressure on the discharge hydraulic pressure path D, wheel hydraulic pressure path B and control valve means VL (wheel cylinder H) side to set values while blocking the flow, and includes a switching valve 6 and a check valve 6a. Configured.

  The switching valve 6 is a normally open type linear solenoid valve interposed between the output hydraulic pressure path A1 leading to the master cylinder MC and the wheel hydraulic pressure path B leading to each wheel brake FL, RR, RL, FR. .

  The check valve 6a is connected to each switching valve 6 in parallel. The check valve 6a is a one-way valve that allows the flow of brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B.

  The suction valve 7 is a normally closed electromagnetic valve provided in the suction fluid pressure passage C, and switches between a state in which the suction fluid pressure passage C is opened and a state in which the suction fluid pressure passage C is shut off.

  The pressure sensor 91 detects the brake hydraulic pressure in the output hydraulic pressure path A1, and the detection result is input to the control unit 100.

Next, details of the control unit 100 will be described.
The control unit 100 is a device that performs control to stabilize the behavior of the vehicle CR by controlling the hydraulic unit 10 and applying a braking force with a target braking force set to the turning outer wheel of the vehicle CR. Therefore, as shown in FIG. 3, the control unit 100 includes a steering angle acquisition unit 110, a vehicle speed calculation unit 120, a steering angular speed calculation unit 130, a standard yaw rate calculation unit 140, a limit yaw rate setting unit 150, and a behavior stability control unit 160. And storage means 190. Note that the output of the pressure sensor 91 is not shown in FIG. 3 because it is not necessary for the characteristic configuration of the vehicle behavior control apparatus A of the present invention. Further, in the following description, for each variable such as the steering angle θ and the steering angular velocity ω, the value at the left turn is positive and the value at the right turn is negative.

  The steering angle acquisition unit 110 is a unit that acquires information on the steering angle θ from the steering angle sensor 93 for each control cycle. The steering angle θ is output to the steering angular velocity calculation means 130 and the normative yaw rate calculation means 140.

  The vehicle speed calculation means 120 is means for acquiring wheel speed information (pulse signal of the wheel speed sensor 92) from the wheel speed sensor 92 for each control cycle, and calculating the wheel speed and the vehicle speed V by a known method. . The calculated vehicle speed V is output to the normative yaw rate calculating means 140 and the limit yaw rate setting means 150.

The steering angular velocity calculation unit 130 is an example of a steering angular velocity acquisition unit, and is a unit that calculates the steering angular velocity ω from the steering angle θ. The steering angular velocity ω can be obtained by differentiating the steering angle θ or calculating the difference between the previous steering angle θ _n−1 and the current steering angle θ _n . The calculated steering angular velocity ω is output to the behavior stabilization control means 160. In the present specification, the subscript n attached after the variable indicates that the variable is the current value, and n−1 indicates the previous value.

  The reference yaw rate calculation means 140 is a means for calculating a reference yaw rate YS as a yaw rate intended by the driver based on the steering angle θ and the vehicle speed V by a known method. The calculated reference yaw rate YS is output to the behavior stabilization control means 160.

  The limit yaw rate setting means 150 is a means for setting a limit yaw rate YL that is a limit yaw rate at which the vehicle can stably travel based on the vehicle speed V. The limit yaw rate YL is set to a smaller value as the vehicle speed V increases. In this embodiment, the calculation is performed on the assumption that the road surface state is a dry road surface. However, when the control unit 100 holds a reliable estimated road surface friction coefficient, the estimated yaw rate is calculated using the estimated road surface friction coefficient. YL may be calculated. The calculated limit yaw rate YL is output to the behavior stabilization control means 160.

  The behavior stabilization control means 160 is a means for executing behavior stabilization control that stabilizes the behavior of the vehicle CR by applying a braking force to the turning outer wheel of the vehicle CR with a set target braking force. In this embodiment, the target hydraulic pressure PT is set as a value corresponding to the target braking force, and the hydraulic pressure is set so that the wheel cylinder pressures of the wheel brakes FL, RR, RL, FR of the turning outer wheel become the target hydraulic pressure PT. The unit 10 is controlled. For this control, the behavior stabilization control means 160 includes a predicted steering angular velocity calculation unit 161, a deviation calculation unit 162, a control intervention threshold setting unit 163, a control intervention determination unit 164, a control end determination unit 165, and a target braking force setting unit. As an example, a target hydraulic pressure setting unit 168 and a control execution unit 169 are included.

  The predicted steering angular velocity calculation unit 161 calculates a predicted steering angular velocity ωP that is a predicted value of the steering angular velocity after the absolute value reaches the peak, based on the increase rate of the absolute value of the steering angular velocity ω during the behavior stabilization control. It is means to do. The predicted steering angular velocity calculation unit 161 monitors changes in the steering angular velocity ω, and determines whether or not the absolute value of the steering angular velocity ω has passed the peak, as shown in FIG. When the predicted steering angular velocity calculation unit 161 determines that the absolute value of the steering angular velocity ω has passed the peak at time t2, the steering angular velocity ω from the time t1 at which the absolute value of the steering angular velocity ω rises to the time t2 at which the peak is reached is reached. Is calculated (broken line gradient). Then, when the absolute value of the steering angular velocity ω is reduced to the comparison start value ωth obtained by multiplying the peak value of the steering angular velocity ω by a predetermined coefficient (time t3), the predicted steering angular velocity ωP is calculated based on the calculated gradient. calculate. Specifically, assuming that the steering angular velocity ω changes in the reverse gradient from the comparison start value ωth by reversing the sign of the gradient while the absolute value of the steering angular velocity ω increases, the predicted steering angular velocity ωP is set to calculate. This predicted steering angular velocity ωP is a steering angular velocity that assumes a case where the steering ST is turned back to the left and right sides. If the difference between the actual steering angular velocity ω and the predicted steering angular velocity ωP is small after time t3, the steering ST If there is a high possibility that the steering wheel ST is turned back and the deviation is large, it can be said that the steering ST is not turned back high.

  The deviation calculating unit 162 calculates a deviation Δω between the predicted steering angular velocity ωP calculated by the predicted steering angular velocity calculating unit 161 and the steering angular velocity ω when the absolute value of the steering angular velocity ω decreases after reaching the peak. Means. The deviation Δω is calculated by ω−ωP when the steering angle θ ≧ 0, that is, during a left turn, and by −ω + ωP when the steering angle θ <0, that is, during a right turn. This deviation Δω is a positive value when the steering angular velocity ω changes more slowly than the predicted steering angular velocity ωP. The deviation calculation unit 162 outputs the calculated deviation Δω to the target hydraulic pressure setting unit 168.

  The control intervention threshold setting unit 163 is a means for setting the control intervention threshold YSth based on the limit yaw rate YL and the steering angular velocity ω. Specifically, the control intervention threshold YSth is calculated by adding the offset amount YD depending on the absolute value of the steering angular velocity ω to the limit yaw rate YL (adding to the negative side for right turn). As shown in FIG. 5, the offset amount YD is a constant value YD1 when the absolute value of the steering angular velocity ω is from 0 to a predetermined value ω1, and is between the predetermined value ω1 and the predetermined value ω2. As the absolute value of ω increases, the absolute value decreases, and in a range larger than the predetermined value ω2, the constant value YD2 is smaller than YD1. For this reason, the absolute value of the control intervention threshold YSth is set smaller as the absolute value of the steering angular velocity ω is larger. As shown in the graph of changes in various yaw rates shown in FIG. 12, the control intervention threshold YSth is calculated as two values for right turn and left turn. The control intervention threshold setting unit 163 outputs the calculated control intervention threshold YSth to the control intervention determination unit 164.

  The control intervention determination unit 164 is a unit that determines that behavior stabilization control is started when the absolute value of the reference yaw rate YS exceeds the absolute value of the control intervention threshold YSth set by the control intervention threshold setting unit 163. When the standard yaw rate YS is positive, it is compared with the control intervention threshold YSth for turning left, and when it is negative, it is compared with the control intervention threshold YSth for turning right.

  When the control intervention determination unit 164 determines to start the behavior stabilization control, the control mode M changes the control mode M from non-controlling (M = 0) to controlling (M = 1). Since the control intervention threshold YSth is set based on the steering angular velocity ω, the control intervention determination unit 164 determines the start of behavior stabilization control based on the steering angular velocity ω.

  The control end determination unit 165 is means for determining the end of the behavior stabilization control. Specifically, the end of the behavior stabilization control is determined when the absolute value of the reference yaw rate YS is smaller than the absolute value of the limit yaw rate YL as an example of the control end threshold. When the control end determination unit 165 determines the end of the behavior stabilization control, the control mode M is set to the end process (M = 2).

  The target hydraulic pressure setting unit 168 is means for setting the target hydraulic pressure PT according to whether the control mode M is under control or is in the end process. First, the case during control will be described. During the control, the target hydraulic pressure setting unit 168 sets the target hydraulic pressure PT based on the standard yaw rate YS, the limit yaw rate YL, and the deviation Δω calculated by the deviation calculating unit 162.

In principle, the target hydraulic pressure setting unit 168 sets the target hydraulic pressure PT to a larger value as the deviation ΔY is larger, based on the standard yaw rate YS and the deviation ΔY between the limit yaw rate YL. Here, ΔY is the value of | YS−YL | as it is when the absolute value | YS−YL | of the difference between the reference yaw rate YS and the limit yaw rate YL increases, and the previous value when it decreases. Calculate to hold. That is, ΔY changes so as to maintain the peak value after | YS−YL | FIG. 6 is a map for setting this basic target hydraulic pressure PT. The larger the deviation ΔY is, the higher the target hydraulic pressure PT is determined. More specifically, the target hydraulic pressure PT gradually increases from 0 to a predetermined value d1, and when the deviation ΔY is equal to or greater than the predetermined value d1, the target hydraulic pressure PT is set to a certain upper limit value PTm. Yes.
Here, since the deviation ΔY reflects the disturbance of the behavior of the vehicle CR, the target hydraulic pressure PT is set according to the magnitude of the deviation ΔY, so that the deviation of the behavior of the vehicle CR is predicted. Since the corresponding braking force can be applied to the turning outer wheel, disturbance of the behavior of the vehicle CR can be reduced.

  The target hydraulic pressure setting unit 168 suppresses the occurrence of understeer caused by applying an excessive braking force to the turning outer wheel with respect to the target hydraulic pressure PT obtained as a principle value, so that the target hydraulic pressure setting unit 168 is 1 or less corresponding to the condition of the vehicle CR. An output coefficient G is set, and a new target hydraulic pressure PT is determined by multiplying the target hydraulic pressure PT by the output coefficient G.

  In the present embodiment, the output coefficient G is set as follows based on the deviation Δω. As shown in FIG. 4, the target hydraulic pressure setting unit 168 compares the deviation Δω with a predetermined threshold C1, and sets the deviation Δω that exceeds the threshold C1 as the corrected deviation ΔωM. Here, as an example, the corrected deviation ΔωM is calculated by selecting the larger one of Δω−C1 and 0.

  Then, the target hydraulic pressure setting unit 168 sets the target hydraulic pressure PT smaller as the corrected deviation ΔωM is larger. Here, as an example, the output coefficient G is calculated by subtracting the value obtained by dividing the corrected deviation ΔωM by the comparison start value ωth from 1, and the output coefficient G is set to 0 when the calculated value is negative. That is, the output coefficient G can be calculated by selecting the larger one of 1−ΔωM / ωth and 0. It is not necessary to reduce the braking force applied to the turning outer wheel when the absolute value of the steering angular velocity ω has decreased after reaching the peak, for example, while the absolute value of the steering angular velocity ω is increasing. Therefore, the output coefficient G is 1. In this way, the target hydraulic pressure setting unit 168 sets the target hydraulic pressure PT smaller as the deviation Δω is larger.

Next, the setting of the target hydraulic pressure PT when the end process is being performed will be described. During termination processing, the target fluid pressure setting unit 168, based on the target hydraulic pressure PT _n-1 of the previous sets a current target hydraulic pressure PT _n based on the map of FIG. Map of FIG. 7, the present target pressure PT _n the larger the target hydraulic pressure PT _n-1 of the previous large, the target hydraulic pressure PT _n of this time, a little than the target hydraulic pressure PT _n-1 of the previous It is set to a small value. When the previous target hydraulic pressure PT _n−1 is smaller than a predetermined value, the current target hydraulic pressure PT _n is set to be zero. If the current target hydraulic pressure PT _n is 0, the target hydraulic pressure setting section 168 changes the control mode M to the non-control in (M = 0).

  The control execution unit 169 is means for controlling the hydraulic pressure unit 10 based on the target hydraulic pressure PT set by the target hydraulic pressure setting unit 168 to control the wheel cylinder pressure of the turning outer wheel to the target hydraulic pressure PT. This control is well known and will not be described in detail. However, in brief, the pump 9 is driven by operating the motor 9, the suction valve 7 is opened, and an appropriate current is supplied to the pressure regulating valve R. Control to flow.

  The storage unit 190 is a unit that appropriately stores constants, parameters, control modes, maps, calculation results, and the like necessary for the operation of the control unit 100.

The process by the control part 100 of the vehicle behavior control apparatus A comprised as mentioned above is demonstrated with reference to FIG. Note that the process of FIG. 8 is repeatedly performed for each control cycle. The initial value of the control mode M is 0.
First, the steering angle acquisition unit 110 acquires the steering angle θ from the steering angle sensor 93, and the vehicle speed calculation unit 120 acquires the wheel speed from the wheel speed sensor 92 (S101). Then, the steering angular speed calculation means 130 calculates the steering angular speed ω from the steering angle θ, and the vehicle speed calculation means 120 calculates the vehicle speed V from the wheel speed (S102). Next, the normative yaw rate calculating means 140 calculates the normative yaw rate YS based on the steering angle θ and the vehicle speed V (S110). Further, the limit yaw rate setting means 150 sets the limit yaw rate YL based on the vehicle speed V (S111).

  Next, the control intervention threshold setting unit 163 sets the control intervention threshold YSth based on the limit yaw rate YL and the steering angular velocity ω (S112). At this time, as described above, the control intervention threshold value YSth is set by adding the offset amount YD that becomes smaller as the absolute value of the steering angular velocity ω increases as shown in FIG. 5 to the limit yaw rate YL. The threshold YSth decreases as the absolute value of the steering angular velocity ω increases.

  Then, the control intervention determination unit 164 determines whether or not the absolute value of the reference yaw rate YS is larger than the absolute value of the corresponding control intervention threshold YSth for right turn or left turn. When the absolute value of the reference yaw rate YS is larger than the absolute value of the control intervention threshold YSth (S120, Yes), the control intervention determination unit 164 determines the start of control and sets the control mode M to 1 (S121). If the absolute value of the reference yaw rate YS is not greater than the absolute value of the control intervention threshold YSth (S120, No), the control intervention determination unit 164 proceeds to step S130 without changing the control mode M.

  Then, the behavior stabilization control means 160 determines whether or not the control mode M is 0, that is, whether or not the control mode M is not in control. If the control mode M is not 0 (S130, No: M = 1 or 2), The processes of steps S200 to S300 are performed, and when the control mode M is 0 (S130, Yes), the process is terminated.

In step S200, the behavior stabilization control means 160 sets the target hydraulic pressure PT. As shown in FIG. 9, the target hydraulic pressure setting unit 168 determines whether or not the control mode M is 1; ), based on the map of FIG. 7, on the basis of the target hydraulic pressure _{PT n-1} previous to determine the current target hydraulic pressure PT _n (S220). Then, when the present target pressure PT _n is 0 (S221, Yes), the control mode M to 0 means that termination process has been completed (S222). On the other hand, if the present target pressure PT _n is not 0 (S221, No), the process ends without changing the control mode M.

  If it is determined in step S210 that the control mode M is 1 (S210, Yes), the target hydraulic pressure setting unit 168 sets the target hydraulic pressure PT from the map of FIG. 6 based on the deviation ΔY (S211). On the other hand, the behavior stabilization control means 160 sets the output coefficient G in step S500.

  As shown in FIG. 10, in setting the output coefficient G, first, the predicted steering angular velocity calculation unit 161 calculates the predicted steering angular velocity ωP in steps S510 to S521. Specifically, the predicted steering angular velocity calculation unit 161 determines whether or not the absolute value of the steering angular velocity ω has passed a peak. If the absolute value of the steering angular velocity ω is decreasing after the peak (S510, Yes), the absolute value of the steering angular velocity ω is determined. The gradient when the value increases is calculated (S511). Then, a comparison start value ωth is calculated by multiplying the peak value of the absolute value of the steering angular velocity ω by a predetermined coefficient (S512), and the process proceeds to step S520. The above steps S511 and S512 need only be performed once when the absolute value of the steering angular velocity ω has passed the peak (the flow for that is omitted). On the other hand, when the absolute value of the steering angular velocity ω has not passed the peak (S510, No), the process proceeds to step S520.

  In step S520, the predicted steering angular velocity calculation unit 161 determines whether the absolute value of the steering angular velocity ω has passed the peak and the absolute value of the steering angular velocity ω is smaller than the comparison start value ωth, and if this is satisfied (S520). , Yes), the predicted steering angular velocity ωP is calculated based on the increase gradient of the absolute value of the comparison start value ωth and the steering angular velocity ω (S521, see FIG. 4). The deviation calculating unit 162 calculates the deviation Δω by ω−ωP when the steering angle θ ≧ 0, and by −ω + ωP when the steering angle θ <0 (S522).

  Next, the target hydraulic pressure setting unit 168 calculates a corrected deviation ΔωM from the deviation Δω and the threshold value C1 (S523). As shown in FIG. 4, since the deviation Δω is greater than the threshold value C1, the corrected deviation ΔωM is zero, and the corrected deviation ΔωM is 0 until time t4 and increases after time t4. Then, as shown in FIG. 10, the target hydraulic pressure setting unit 168 calculates an output coefficient G of 1 or less based on the corrected deviation ΔωM and the comparison start value ωth (S524). As shown in FIG. 4, the output coefficient G is set so as to decrease as the corrected deviation ΔωM increases. As shown in FIG. 10, the target hydraulic pressure setting unit 168 sets the output coefficient G to 1 when it is determined No in step S520 (S525).

  When the output coefficient G is set, as shown in FIG. 9, the target hydraulic pressure setting unit 168 multiplies the target hydraulic pressure PT by the output coefficient G to set a new target hydraulic pressure PT (S230).

  When the target hydraulic pressure PT is set in this manner, the control execution unit 169 returns the hydraulic pressure unit 10 to the target hydraulic pressure PT so that the hydraulic pressure in the wheel cylinder H of the turning outer wheel becomes the target hydraulic pressure PT. Control is performed (S131).

  Next, the control end determination unit 165 performs control end determination in step S300. Specifically, as shown in FIG. 11, it is determined whether or not the absolute value of the normative yaw rate YS is smaller than the absolute values of the corresponding left and right limit yaw rates YL. If the absolute value is smaller (S310, Yes), the behavior is stable. It is determined that the control is to be ended, and the control mode M is changed to 2 which is in the end process (S311). On the other hand, when the absolute value of the normative yaw rate YS is not smaller than the absolute values of the corresponding left and right limit yaw rates YL (S310, No), the process ends without changing the control mode M.

  Changes in various parameters by the above control will be described with reference to FIG. Although the steering angle θ is not shown in FIG. 12, the steering angle θ changes with substantially the same phase as the reference yaw rate YS. In the following description, the value of each parameter is discussed with respect to the magnitude, and “absolute value” is omitted, and each parameter is expressed in the same way as a positive value during right turn.

  As shown in the change in the standard yaw rate YS in FIG. 12, the vehicle CR turns the steering ST to the left between times t11 and t15, and turns the steering ST to the right between times t15 and t18. Since the limit yaw rate YL decreases as the vehicle speed V increases, the limit yaw rate YL gradually increases as the vehicle speed V gradually decreases after time t11. Here, when the steering angular velocity ω increases after time t11, the left turn control intervention threshold YSth decreases rapidly. For this reason, at time t12 before starting to turn right, the reference yaw rate YS exceeds the control intervention threshold YSth for turning left, and the control mode M is changed from 0 to 1. And from time t12 to t13, the control intervention threshold YSth increases as the steering angular velocity ω decreases. When the reference yaw rate YS facing left decreases and at time t14, the reference yaw rate YS becomes smaller than the limit yaw rate YL as the control end threshold, and the control mode M becomes 2. Then, when the termination process is finished, the control mode M becomes zero.

  When the steering ST is turned back to the right after time t13, the steering angular velocity ω increases to the right, so that the control intervention threshold YSth for right turn decreases, and at time t16, the reference yaw rate YS is used for right turn. When the control intervention threshold value YSth is exceeded, the control mode M changes from 0 to 1. Then, the normal yaw rate YS facing right decreases, and at time t17, the standard yaw rate YS becomes smaller than the limit yaw rate YL and the control mode M becomes 2. Then, when the termination process is finished, the control mode M becomes zero.

The effect of the vehicle behavior control apparatus A as described above will be described with reference to FIGS.
FIG. 13 and FIG. 14 show changes in parameters when the vehicle returns straight from the straight traveling state to the left, right, or left. FIG. 13 shows a case where the control start determination in the prior art is used. In the determination of the start, as in JP 2011-102048, it is determined that the control is started when the deviation between the corrected normative yaw rate set based on the lateral acceleration and the actual yaw rate exceeds a threshold value. . The threshold value is not changed according to the steering angular velocity.

  In the prior art, as shown in FIG. 13 (a), the start of control is determined at time t21 after the steering angle θ reaches a peak due to turning the steering to the left, that is, after starting to turn back to the right. Has been. As shown in FIG. 13B, the brake fluid pressure is not generated sufficiently during the left turn that is the first steering, but is generated only at a sufficient level during the right turn that is the second steering. doing. Therefore, as shown in FIG. 13A, at the time t25, the actual yaw rate is decreased, and the difference between the steering angle and the actual yaw rate is increased, resulting in an understeer tendency. At time t24, the slip angle β (the deviation angle between the traveling direction of the vehicle and the steering direction) indicating the state of disturbance of the vehicle behavior is largely fluctuated, and the behavior of the vehicle is disturbed.

  On the other hand, in the vehicle behavior control apparatus A of the present embodiment, as shown in FIG. 14A, the control is started at time t31 before the steering angle θ reaches the peak, that is, at the first turning of the steering ST. Has been determined. Then, as shown in FIG. 14B, a sufficiently large brake fluid pressure is generated during the left turn which is the first steering. For this reason, the disturbance of the behavior of the vehicle is suppressed, and as shown in FIG. 14A, the slip angle β is kept small at the time t35 during turning to the right.

15 and 16 show changes in parameters when the vehicle turns right from the straight traveling state and returns straight. FIG. 15 shows the case of a comparative example in which the output coefficient G is fixed to 1 without changing the embodiment, and FIG. 16 shows the case of this embodiment.
In the comparative example, as shown in FIG. 15 (a), after the steering is turned to the right, when the behavior stabilization control starts at time t41 as shown in FIG. 15 (b), the behavior stabilization control ends until time t43. A relatively large brake fluid pressure continues to be generated. Therefore, in the second half of the right turn, the braking force of the turning outer wheel becomes excessive, and as shown in FIG. 15A, the actual yaw rate decreases at time t42, and the difference between the steering angle θ and the actual yaw rate Has become understeering.

  On the other hand, in this embodiment, after turning the steering ST to the right as shown in FIG. 16 (a), the brake fluid pressure rises as shown in FIG. 16 (b), and then as shown in FIG. 16 (c). The output coefficient G gradually decreases from time t52 to t53. This is because the deviation Δω between the predicted steering angular velocity ωP and the steering angular velocity ω has increased as a result of not turning to the left after turning right (see FIG. 4). Therefore, the brake fluid pressure is suppressed to a small value from time t52 to t53. As a result, the braking force of the turning outer wheel is suppressed to a small level, and as can be seen from the change in the actual yaw rate in FIG. 16A, the decrease in the actual yaw rate is suppressed and the tendency to understeer is suppressed.

  As described above, according to the vehicle behavior control apparatus A of the present embodiment, it is possible to determine the start of behavior stabilization control based on the steering angle θ, the steering angular velocity ω, and the vehicle speed V without being based on the actual yaw rate. Therefore, it can be determined that the behavior stabilization control is started before the steering result of the steering ST appears in the actual behavior of the vehicle CR. Therefore, behavior stabilization control can be started at an early stage, and disturbance in behavior of the vehicle CR can be suppressed.

  The vehicle behavior control apparatus A can start the behavior stabilization control at an initial stage where the steering ST is cut from the straight traveling state because the control intervention threshold YSth decreases as the absolute value of the steering angular velocity ω increases.

  Further, since the vehicle behavior control apparatus A increases the target hydraulic pressure PT as the deviation ΔY between the reference yaw rate YS and the limit yaw rate YL increases, the braking force according to the predicted disturbance in the behavior of the vehicle CR. Can be given to the turning outer wheel, so that the disturbance of the behavior of the vehicle CR can be reduced.

  Further, the vehicle behavior control device A calculates the deviation Δω between the steering angular velocity ω and the predicted steering angular velocity ωP when the absolute value of the steering angular velocity ω has decreased after reaching the peak, and the larger the deviation Δω, the more the target Since the hydraulic pressure PT is set to be small, it is possible to predict a target travel line by the driver and adjust the target hydraulic pressure so as to return to the target travel line. For this reason, generation | occurrence | production of the understeer state by excessive control can be suppressed.

  In addition, the target hydraulic pressure setting unit 168 reduces the target hydraulic pressure PT according to the magnitude of the deviation Δω only when the deviation Δω exceeds a predetermined value, thereby increasing the hydraulic pressure while the deviation Δω is small. Therefore, the behavior of the vehicle CR can be stabilized.

  In addition, the vehicle behavior control device A determines that the behavior stabilization control is to be terminated when the absolute value of the reference yaw rate YS falls below the limit yaw rate YL by the control end determination unit 165. However, since the target hydraulic pressure setting unit 168 adjusts the target hydraulic pressure PT in accordance with the deviation Δω, the target hydraulic pressure setting unit 168 suppresses the understeer tendency without using the control end determination based on the actual yaw rate. The behavior of CR can be stabilized.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be implemented in various forms as exemplified below.

  In the embodiment, the target hydraulic pressure is set as an example of the target braking force, but the target braking force itself may be set as the target value.

  In the above embodiment, the target hydraulic pressure PT is set without distinguishing the front wheel and the rear wheel among the turning outer wheels, but the size of the target hydraulic pressure PT is set for each wheel according to the weight distribution of the front and rear wheels. You may adjust.

  In the embodiment described above, only the case where the vehicle behavior stabilization control is executed has been described. However, the vehicle behavior control device A may be configured to perform antilock brake control and the like together.

  In the above-described embodiment, the present invention is applied to the brake system configured such that the hydraulic pressure of the master cylinder MC is transmitted to the wheel cylinder H. However, the vehicle behavior control device of the present invention pressurizes the brake fluid with an electric motor, The present invention can also be applied to a so-called by-wire type brake device.

DESCRIPTION OF SYMBOLS 10 Hydraulic pressure unit 100 Control part 110 Steering angle acquisition means 120 Vehicle speed calculation means 130 Steering angular speed calculation means 140 Standard yaw rate calculation means 150 Limit yaw rate setting means 160 Behavior stability control means 161 Predictive steering angular speed calculation part 162 Deviation calculation part 163 Control intervention Threshold setting unit 164 Control intervention determination unit 165 Control end determination unit 168 Target hydraulic pressure setting unit A Vehicle behavior control device

Claims (4)

Steering angle acquisition means for acquiring the steering angle;
Steering angular velocity acquisition means for acquiring the steering angular velocity;
Vehicle speed acquisition means for acquiring the vehicle speed;
A reference yaw rate calculating means for calculating a reference yaw rate of the vehicle based on the vehicle speed and the steering angle;
Limit yaw rate setting means for setting a limit yaw rate that is a limit yaw rate at which the vehicle can stably travel based on the vehicle speed;
A behavior stabilization control means for performing behavior stabilization control for stabilizing the behavior of the vehicle by applying a braking force to the turning outer wheel of the vehicle with a set target braking force;
The behavior stabilization control means includes
A control intervention threshold setting unit that sets a control intervention threshold based on the limit yaw rate and the steering angular velocity;
A vehicle behavior control device comprising: a control intervention determination unit that determines to start the behavior stabilization control when the reference yaw rate exceeds the control intervention threshold.   The vehicle behavior control device according to claim 1, wherein the control intervention threshold setting unit sets the absolute value of the control intervention threshold to be smaller as the absolute value of the steering angular velocity is larger.   3. The vehicle behavior control device according to claim 1, wherein the behavior stabilization control unit increases the target braking force as the deviation between the reference yaw rate and the limit yaw rate increases.   The behavior stabilization control unit includes a control end determination unit that determines to end the behavior stabilization control when the absolute value of the reference yaw rate is below a control end threshold, and sets the control end threshold to the vehicle speed. 4. The vehicle behavior control device according to claim 1, wherein the vehicle behavior control device is set to a smaller value as the vehicle speed increases. 5.

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