WO2020162429A1

WO2020162429A1 - Eccentric load determination device of vehicle and automatic brake device of vehicle provided with same

Info

Publication number: WO2020162429A1
Application number: PCT/JP2020/004049
Authority: WO
Inventors: 鈴木　孝治; 千裕新田
Original assignee: 株式会社アドヴィックス
Priority date: 2019-02-04
Filing date: 2020-02-04
Publication date: 2020-08-13

Abstract

This eccentric load determination device KT determines an eccentric load state in which a load mounted in a vehicle lies in eccentricity in the vehicle width direction. The eccentric load determination device is provided with: a first direction acquisition means DD which acquires a road direction Dd in which a vehicle travels; a second direction acquisition means VD which acquire a proceeding direction Vd of the vehicle; and a controller ECU which determines an eccentric load state on the basis of a deviation Ha between the road direction Dd and the proceeding direction Vd, when the deceleration Ga is equal to or greater than a prescribed value gx. This automatic brake device JS prevents a collision with an object in front of the vehicle. The controller ECU calculates an eccentric load index Kt, which is the determination result of the eccentric load state, and adjusts, on the basis of the eccentric load index Kt, at least one among a fore and aft distribution ratio Hx and a left and right distribution ratio Hy of a braking force Fv to be applied to the vehicle.

Description

Vehicle single load determination device and vehicle automatic braking device including the determination device

The present disclosure relates to a vehicle single load determination device, and a vehicle automatic braking device including the determination device.

When a load (load) is loaded unevenly in the vehicle width direction on a truck, a commercial van, etc., the position of the center of gravity of the vehicle is biased, so vehicle deflection may occur during execution of automatic braking control. The applicant has developed a device for determining the state of one-sided loading of a vehicle (the state where the loaded load is biased in the vehicle width direction). For example, as described in Patent Document 1, "G sensor 2 (lateral acceleration detecting means) that detects the acceleration Gy of the vehicle 20 in the vehicle width direction and yaw rate sensor 3 (yaw rate detection that detects the yaw rate γ of the vehicle 20. Means), a vehicle speed sensor 4 (vehicle speed detecting means) for detecting the vehicle speed V of the vehicle 20, and an ECU 6. The ECU 6 has yaw rates γ at different vehicle speeds V during acceleration or deceleration of the vehicle 20. When all of the absolute values of are equal to or less than a predetermined threshold yaw rate γk, the yaw rate determination unit (running state determination unit) that determines that the vehicle 20 is traveling substantially straight on a substantially flat road surface, and the vehicle 20 is determined by the yaw rate determination unit. A single load determination unit (a single load determination means) that determines that the vehicle 20 is in a single load state based on the lateral acceleration Gy when it is determined that the vehicle is traveling substantially straight on a substantially flat road surface, Device.

In the device of Patent Document 1, when it is determined that the vehicle is traveling substantially straight on a substantially flat road surface, the one-sided load state of the vehicle is determined based on the lateral acceleration detected by the lateral acceleration detecting means. .. For example, "the vehicle is traveling straight on a substantially flat road surface" means that the absolute values of the yaw rates at a plurality of different vehicle speeds during acceleration or deceleration of the vehicle are all equal to or less than a predetermined threshold yaw rate, or It is determined when the absolute values of the steering angles at a plurality of different vehicle speeds during acceleration or deceleration of the vehicle are all less than or equal to a predetermined threshold steering angle.

▽ Lateral acceleration detection means (also called "lateral acceleration sensor") is equipped in standard rollover prevention device and standard sideslip prevention device. A signal from the lateral acceleration sensor is input to an electronic control unit ECU (also referred to as “controller”) via an AD (analog/digital) conversion circuit. In the device of Patent Document 1, when the vehicle is tilted by a single load, the single load state is determined based on the influence of gravity on the lateral acceleration. However, since the inclination of the vehicle due to the single load is not so large, the lateral acceleration resolution (least significant bit LSB) by the AD conversion circuit cannot be sufficiently secured. For this reason, it is desired that the one-sided load state can be determined with higher accuracy.

JP2012-171430A

An object of the present invention is to provide a single load determination device for a vehicle, which can accurately determine the single load state.

The vehicle single load determination device determines the single load state in which the load loaded on the vehicle is biased in the vehicle width direction. A single load determination device for a vehicle includes a first direction acquisition unit (DD) for acquiring a road direction (Dd) in which the vehicle is traveling and a second direction acquisition unit (Dd) for acquiring a traveling direction (Vd) of the vehicle. VD) and the deceleration (Ga) of the vehicle are equal to or greater than a predetermined value (gx), the vehicle is in the single load state based on a deviation (Ha) between the road direction (Dd) and the traveling direction (Vd). And a controller (ECU) that determines that there is.

It is a whole lineblock diagram for explaining automatic braking device JS provided with single load judging device KT of vehicles. It is a flowchart for demonstrating the arithmetic processing in single load determination apparatus KT. It is a functional block diagram for demonstrating the automatic braking device JS using the determination result Kt in the single load determination device KT.

<Symbols of components, subscripts at the end of the symbol>
In the description below, components such as “ECU” and the like, components, calculation processes, signals, characteristics, and values having the same symbol have the same function. The subscripts "i" to "l" added to the end of the various symbols relating to the wheels are comprehensive symbols indicating which of the wheels it belongs to. Specifically, “i” indicates the right front wheel, “j” indicates the left front wheel, “k” indicates the right rear wheel, and “l” indicates the left rear wheel. For example, in each of the four wheel cylinders, the right front wheel wheel cylinder CWi, the left front wheel wheel cylinder CWj, the right rear wheel wheel cylinder CWk, and the left rear wheel wheel cylinder CWl are described. Furthermore, the subscripts "i" to "l" at the end of the symbols can be omitted. When the subscripts “i” to “l” are omitted, each symbol represents the generic name of each of the four wheels. For example, "WH" represents each wheel and "CW" represents each wheel cylinder.

The subscripts “f” and “r” added to the end of various symbols are inclusive symbols that indicate which of them in the front-back direction of the vehicle. Specifically, “f” indicates a front wheel and “r” indicates a rear wheel. For example, the front wheels WHf and the rear wheels WHr are described as wheels. Further, the suffixes "f" and "r" at the end of the symbols can be omitted. When the subscripts “f” and “r” are omitted, each symbol represents its generic name. For example, "WH" represents each of the four wheels.

In the fluid path, the side close to the reservoir RV and away from the wheel cylinder CW is called “upper”, and the side closer to the wheel cylinder CW and far from the reservoir RV is called “lower”. Here, the fluid path is a path for moving the brake fluid BF that is the working fluid of the automatic braking device JS, and corresponds to a brake pipe, a fluid unit channel, a hose, and the like. The inside of each fluid path is filled with the braking fluid BF.

<Automatic braking device JS equipped with a vehicle single load determination device KT>
An automatic braking device JS including a single load determination device KT will be described with reference to the overall configuration diagram of FIG. 1. The vehicle has two fluid paths (that is, two braking systems). Specifically, a front wheel system connected to the right front wheel and left front wheel wheel cylinders CWi and CWj (=CWf), and a rear wheel system connected to the right rear wheel and left front wheel cylinders CWk and CWl (=CWr). Is provided. That is, a so-called front-rear type (also referred to as "II type") is used as the two braking systems of the vehicle.

A vehicle including the automatic braking device JS is provided with a known braking operation member BP, a wheel cylinder CW, and a master cylinder CM. By operating the braking operation member (for example, the brake pedal) BP, the hydraulic pressure (braking hydraulic pressure) Pw of the wheel cylinder CW is adjusted, the braking torque Tq of the wheel WH is adjusted, and the braking force is generated on the wheel WH. To be done.

Each wheel WH of the vehicle is equipped with a wheel speed sensor VW so as to detect the wheel speed Vw. The signal of the wheel speed Vw is used for independent braking control of each wheel such as anti-skid control (anti-lock brake control) for suppressing the lock tendency of the wheel WH (that is, excessive deceleration slip).

The steering operation member (eg, steering wheel) is provided with a steering angle sensor SA so as to detect the steering angle Sa. The vehicle body of the vehicle is provided with a yaw rate sensor YR so as to detect a yaw rate (yaw angular velocity) Yr. Further, a longitudinal acceleration sensor GX and a lateral acceleration sensor GX are provided so as to detect acceleration (longitudinal acceleration) Gx in the front-rear direction (travel direction) and acceleration (lateral acceleration) Gy in the lateral direction (direction perpendicular to the traveling direction) of the vehicle. An acceleration sensor GY is provided. These signals (Sa, Yr, etc.) are used for vehicle motion control such as vehicle stabilization control (so-called ESC) that suppresses excessive oversteer behavior and deflection.

A braking operation amount sensor BA is provided so as to detect the operation amount Ba of the braking operation member BP (brake pedal) by the driver. As the braking operation amount sensor BA, a master cylinder hydraulic pressure sensor PM that detects a hydraulic pressure (master cylinder hydraulic pressure) Pm in the master cylinder CM, an operational displacement sensor SP that detects an operational displacement Sp of the braking operation member BP, and a braking operation. At least one of the operating force sensors FP that detects the operating force Fp of the operating member BP is adopted. That is, the operation amount sensor BA detects at least one of the master cylinder hydraulic pressure Pm, the operation displacement Sp, and the operation force Fp as the braking operation amount Ba.

Signals of wheel speed Vw, steering angle Sa, actual yaw rate Yr, longitudinal acceleration (deceleration) Gx, lateral acceleration Gy, braking operation amount Ba (Pm, Sp, Fp), etc. detected by the above-mentioned respective sensors (VW etc.) Is input to the braking controller ECB.

-Vehicles will be equipped with a driving support system to avoid collisions with obstacles or reduce damage during collisions. The driving support system includes a distance sensor OB and a driving support controller ECJ. The distance sensor OB detects a distance (relative distance) Ob between an object existing in front of the host vehicle (another vehicle, a fixed object, a person, a bicycle, etc.) and the host vehicle. For example, as the distance sensor OB, a camera system KM, a radar or the like is adopted. The relative distance Ob is input to the driving support controller ECJ. The driving assist controller ECJ calculates the required deceleration Gs based on the relative distance Ob. The required deceleration Gs is a target value of the deceleration of the vehicle in order to prevent the vehicle from hitting an object. Since the automatic braking control is a braking control that operates urgently, the required deceleration Gs is, for example, "0.7G to 0.8G" as the deceleration corresponding to the vicinity of the limit of the friction coefficient of the road surface with which the wheel WH contacts. “Predetermined value within the range up to” or more. The driving support controller ECJ is connected to the communication bus BS, and the required deceleration Gs is transmitted to the braking controller ECB via the communication bus BS.

In addition, the driving assistance controller ECJ provides assistance for lane departure prevention. For example, a lane (white line or the like) on the road is recognized based on the image in front of the vehicle acquired by the camera system KM (corresponding to one of the “first direction acquisition means DD”). When the probability of the vehicle deviating from the lane is high, the electric power steering generates an appropriate steering torque to assist the lane keeping. That is, the driving assistance controller ECJ determines the road direction Dd by recognizing the lane based on the image of the camera system KM. Here, the “road direction Dd” is the direction (direction) the road is heading, and is the direction in which the running vehicle should travel.

Even if the lane recognition is insufficient, the camera system KM can recognize the vehicle traveling ahead and determine the road direction Dd. The road direction Dd is transmitted from the driving support controller ECJ to the braking controller ECB via the communication bus BS.

The vehicle is equipped with a navigation system NV (corresponding to one of "first direction acquisition means DD"). The navigation system NV has a function of electronically grasping the current position of the own vehicle and performing route guidance to a destination based on the own vehicle position. The navigation system NV includes a global positioning system GP and a navigation controller ECN.

The Global Positioning System GP is a "Global Positioning System (GPS)", which receives signals from a plurality of GPS satellites and knows the current position Vp of the vehicle (satellite positioning system (measures the current position on the earth). System). The position Vp of the vehicle is output to the navigation controller ECN by the global positioning system GP.

The navigation controller ECN is an electronic control unit for navigation. The navigation controller ECN includes map data (map information) MP including detailed road information. In the navigation controller ECN, the vehicle position Vp is associated with the map information MP to determine the direction of the road on which the vehicle is currently traveling and the direction (road direction) Dd in which the vehicle should travel. The navigation controller ECN is connected to the communication bus BS, and the road direction Dd is transmitted from the navigation controller ECN to the braking controller ECB via the communication bus BS.

<<Brake Controller ECB>>
The automatic braking device JS includes a braking controller ECB and a fluid unit HU. The braking controller (also referred to as "electronic control unit for braking") ECB is composed of an electric circuit board on which a microprocessor MC and the like are mounted, and a control algorithm programmed in the microprocessor MC. The braking controller ECB is network-connected to the driving support controller ECJ, the navigation controller ECN, etc. via the vehicle-mounted communication bus BS so as to share signals (detection value, calculation value, etc.). The controllers connected via the communication bus BS are collectively referred to as "controller (electronic control unit) ECU". For example, the single load determination device KT (a control algorithm described later) may be included in the braking controller ECB.

The braking controller ECB (electronic control unit) controls the electric motor ML of the fluid unit HU and the solenoid valves UP, VI, VO. Specifically, drive signals Up, Vi, Vo for controlling the various solenoid valves UP, VI, VO are calculated based on the control algorithm in the microprocessor MC. Similarly, the drive signal Ml for controlling the electric motor ML, which is the drive source of the electric pump DL, is calculated.

The braking controller ECB is provided with a drive circuit DR so as to drive the solenoid valves UP, VI, VO and the electric motor ML. A bridge circuit is formed in the drive circuit DR by switching elements (power semiconductor devices such as MOS-FETs and IGBTs) so as to drive the electric motor ML. The energization state of each switching element is controlled based on the motor drive signal Ml, and the electric motor ML is driven. Further, in the drive circuit DR, the energized state (that is, the excited state) to the solenoid valves UP, VI, VO is controlled and they are driven.

<<Fluid unit HU>>
The fluid unit HU is connected to the front wheel and rear wheel master cylinder fluid passages HMf and HMr. At the portions Btf and Btr (branch portions) in the fluid unit HU, the two master cylinder fluid passages HMf and HMr are branched into four wheel cylinder fluid passages HWi to HWl and connected to the four wheel cylinders CWi to CWl. It The fluid unit HU includes a pressure regulating valve UP, an electric pump DL, a low pressure reservoir RL, a master cylinder hydraulic pressure sensor PM, an inlet valve VI, and an outlet valve VO.

The front and rear wheel pressure regulating valves UPf and UPr (=UP) are provided in the front and rear wheel master cylinder fluid passages HMf and HMr (=HM). As the pressure regulating valve UP, a linear solenoid valve (also referred to as “proportional valve” or “differential pressure valve”) whose valve opening amount (lift amount) is continuously controlled based on the energized state (for example, supply current). Is adopted. The pressure regulating valve UP is controlled by the controller ECB based on the front wheel and rear wheel drive signals Upf, Upr (=Up). Here, normally open solenoid valves are adopted as the front wheel and rear wheel pressure regulating valves UPf and UPr.

The electric pump DL is composed of one electric motor ML and two fluid pumps QLf and QLr (=QL). By the electric motor ML, the front wheel and rear wheel fluid pumps QLf and QLr are integrally rotated and driven. By front and rear wheel fluid pumps QLf and QLr, from front wheels and rear wheel suction portions Bsf and Bsr located between front wheels and rear wheel pressure regulating valves UPf and UPr and master cylinder CM (that is, above pressure regulating valve UP). The braking fluid BF is pumped up. The pumped braking fluid BF is discharged to the front wheel/rear wheel discharge parts Btf, Btr located below the front wheel/rear wheel pressure regulating valves UPf, UPr. Front and rear wheel low pressure reservoirs RL1 and RL2 (=RL) are provided on the suction sides of the front and rear wheel fluid pumps QLf and QLr.

When the fluid pump QL is driven, a flow (circulation) of the circulating braking fluid BF is formed. When the pressure regulating valve UP is not energized and the normally open type pressure regulating valve UP is in the fully open state, the hydraulic pressure at the upper portion of the pressure regulating valve UP (that is, the master cylinder hydraulic pressure Pm) and the lower portion of the pressure regulating valve UP are set. And the actual hydraulic pressure Pp (referred to as “adjusted hydraulic pressure”). The energization amount to the normally open front wheel and rear wheel pressure regulating valves UPf and UPr is increased, and the valve opening amount is decreased. The front and rear wheel pressure regulating valves UPf and UPr restrict the circulation of the braking fluid BF, and the orifice effect causes the front and rear wheel adjusting fluid pressures (actual fluid pressures) Ppf and Ppr (=Pp) to be the front and rear wheel masters. The cylinder hydraulic pressures Pmf and Pmr (=Pm) are increased (hence "Pp>Pm"). That is, the electric pump DL and the pressure regulating valve UP adjust the differential pressure between the master cylinder hydraulic pressure Pm and the adjusted hydraulic pressure Pp. By controlling the electric pump DL and the pressure regulating valve UP, the adjusted hydraulic pressure Pp (as a result, the braking hydraulic pressure Pw of the wheel cylinder CW) is higher than the master cylinder hydraulic pressure Pm corresponding to the operation of the braking operation member BP. Will be increased.

The front and rear wheel master cylinder hydraulic pressure sensors PM1 and PM2 are provided above the pressure regulating valve UP (on the side close to the master cylinder CM) so as to detect the front and rear wheel master cylinder hydraulic pressures Pmf and Pmr. Basically, since “Pmf=Pmr”, one of the front wheel and rear wheel master cylinder hydraulic pressure sensors PM1 and PM2 can be omitted.

Inlet valves VIi to VIl (=VI) are provided in the wheel cylinder fluid passages HWi to HWl (=HW). The wheel cylinder fluid passage HW is connected to the low pressure reservoir RL via a normally closed outlet valve VO below the inlet valve VI (between the inlet valve VI and the wheel cylinder CW). The fluid passage that connects the wheel cylinder fluid passage HW and the low pressure reservoir RL is referred to as "reservoir fluid passage HR". Therefore, each outlet valve VO is provided in each reservoir fluid passage HR.

A normally open on/off solenoid valve is adopted as the inlet valve VI. The open state of the inlet valve VI is adjusted by the drive signal Vi calculated based on the duty ratio Du. Here, the “duty ratio” is the ratio of the ON time (energization time) of a pulse in a pulse train that continues at a constant cycle. Further, as the outlet valve VO, a normally closed on/off solenoid valve is adopted. Similar to the inlet valve VI, the open state of the outlet valve VO is also adjusted by the drive signal Vo calculated based on the duty ratio Du (ratio of energization time per unit time).

In the inlet valve VI and the outlet valve VO, the configuration related to each wheel WH is the same. For example, in order to reduce the hydraulic pressure Pw in the wheel cylinder CW, the inlet valve VI is closed and the outlet valve VO is opened. Inflow of the brake fluid BF from the inlet valve VI is blocked, the brake fluid BF in the wheel cylinder CW flows out to the low pressure reservoir RL, and the brake fluid pressure Pw is reduced. Further, since the braking hydraulic pressure Pw is increased, the inlet valve VI is opened and the outlet valve VO is closed. The outflow of the braking fluid BF to the low pressure reservoir RL is blocked, the adjustment fluid pressure Pp adjusted by the pressure adjustment valve UP is introduced into the wheel cylinder CW, and the braking fluid pressure Pw is increased. Further, in order to maintain the hydraulic pressure (braking hydraulic pressure) Pw in the wheel cylinder CW, both the inlet valve VI and the outlet valve VO are closed. That is, the brake fluid pressure Pw of the wheel cylinder CW can be individually adjusted by controlling the inlet valve VI and the outlet valve VO.

<Processing by the single load determination device KT>
With reference to the flowchart of FIG. 2, the processing in the single load determination device KT will be described. For example, this single load determination processing (also referred to as “single load index calculation processing KT”) is an algorithm programmed in the microprocessor in the controller ECU (=ECB, ECJ, ECN). Since various signals are shared via the communication bus BS, the single load determination process KT may be processed by any of the controllers ECB, ECJ, ECN and the like.

In step S110, signals (detected values of various sensors and calculated values of controllers ECB, ECN, ECJ (=ECU)) are read. Specifically, the vehicle body speed Vx calculated based on the longitudinal acceleration (forward/backward deceleration) Gx, the steering angle Sa, the wheel speed Vw, and the like are read.

In step S120, the road direction Dd in which the vehicle is traveling is acquired by the first direction acquisition means DD. Here, the road direction Dd is the direction (direction) of the road on which the vehicle is traveling, and is the direction in which the traveling vehicle should travel.

In step S130, the traveling direction Vd of the vehicle is acquired by the second direction acquisition means VD. Here, the traveling direction Vd of the vehicle is the direction instructed by the operation of the steering operation member SW. Hereinafter, a combination example of the first direction acquisition unit DD and the second direction acquisition unit VD will be described.

(1) First combination example A navigation system NV is adopted as the first direction acquisition means DD. The navigation system NV is provided with a global positioning system GP and map information (road map) MP. The current position Vp of the own vehicle obtained by the global positioning system GP is collated (corresponding) with the map information MP and used as a reference road direction Dd (the direction of the road in front of the vehicle, which is also referred to as “reference direction”). ) Is calculated.

A steering angle sensor SA is adopted as the second direction acquisition means VD. The traveling direction Vd of the vehicle is calculated based on the steering angle Sa corresponding to the operation amount of the steering operation member SW. That is, the traveling direction Vd is the traveling direction of the vehicle required by the steering angle Sa of the steering operation member SW.

(2) Second combination example As the first direction acquisition means DD, a camera system KM for photographing the front of the vehicle is adopted. The lane (white line or the like) on the road is recognized based on the image in front of the vehicle obtained by the camera system KM. Then, the road direction Dd (reference direction) is calculated based on the lane. Even if the lane is not recognized sufficiently, the camera system KM can recognize the vehicle traveling ahead and determine the road direction Dd based on the image of the vehicle traveling ahead.

Similar to the first example, the steering angle sensor SA is adopted as the second direction acquisition means VD, and the vehicle traveling direction Vd is calculated based on the steering angle Sa. That is, the traveling direction Vd is the traveling direction of the vehicle indicated by the steering angle Sa.

(3) Third Example of Combination A yaw rate sensor YR is adopted as the first direction acquisition means DD. The actual turning amount Ya is calculated based on the actually generated yaw rate Yr detected by the yaw rate sensor YR. Specifically, the actual turning amount Ya is determined as the road direction Dd (reference direction).

A steering angle sensor SA is adopted as the second direction acquisition means VD. A reference turning amount Ys corresponding to the actual turning amount Ya is calculated based on the steering angle Sa. The reference turning amount Ys is determined as the traveling direction Vd of the vehicle required by the steering angle Sa. The reference turning amount Ys is a yaw rate that should occur when the single load state does not occur (when the load is uniform in the vehicle width direction). That is, the reference turning amount Ys is a state amount in the yaw direction, which indicates a case where the vehicle is not deflected due to the single load state.

In step S140, the actual deceleration Ga is calculated based on at least one of the wheel speed Vw and the detected deceleration Gx. The actual deceleration Ga is the deceleration (negative acceleration) in the front-rear direction (travel direction) of the vehicle that is actually occurring. For example, the vehicle body speed Vx is calculated based on the wheel speed Vw, and the actual deceleration Ga is determined based on the vehicle body speed Vx. Specifically, the vehicle speed Vx is time-differentiated to calculate the actual deceleration Ga. Further, the actual deceleration Ga is determined based on the longitudinal acceleration Gx (detection value). Further, the actual vehicle deceleration Ga may be calculated based on the differential value (calculated value) of the vehicle body speed Vx and the longitudinal acceleration Gx (detected value) so as to improve robustness.

In step S150, "whether or not the actual deceleration Ga is equal to or greater than a predetermined deceleration gx" is determined based on the actual deceleration Ga. Here, the predetermined deceleration gx is a threshold value for determination and is a preset constant. In the automatic braking control, the required deceleration Gs is instructed as "quick braking in an emergency (emergency braking)" at or above "the deceleration within the range of 0.7G to 0.8G". The regular braking (service braking) is performed at or below "the deceleration within the range of 0.3G to 0.4G". Therefore, the predetermined deceleration gx may be set as a deceleration corresponding to the emergency braking and the regular braking. If “Ga≧gx” and step S150 is positive, the process proceeds to step S160. If “Ga<gx” and step S150 is negative, the process returns to step S110.

In step S160, the road direction Dd and the traveling direction Vd are compared, and the deviation Ha is calculated. The deviation Ha is a direction difference (azimuth difference) of the vehicle traveling direction Vd with respect to the road direction Dd when the road direction Dd is used as a reference. That is, the azimuth deviation Ha is a state quantity indicating the degree of vehicle deflection during braking. The “direction” is a state variable that indicates which direction the direction is facing with respect to the reference direction (road direction Dd). For example, the "angle" is adopted as the physical quantity of the azimuth. In this case, the deviation Ha is determined as the azimuth deviation.

The deviation (azimuth deviation) Ha is determined by subtracting the road direction Dd (reference direction) from the traveling direction Vd (that is, “Ha=Vd−Dd”). The deviation Ha is a state quantity having a positive or negative sign (“+” or “−”). The sign of the deviation Ha indicates in which of the left and right directions (vehicle width direction) the vehicle deflection is likely to occur.

In step S170, "whether or not the magnitude (absolute value) of the deviation Ha is a predetermined amount hx or more" is determined based on the deviation Ha of the azimuth angle. Here, the predetermined amount hx is a threshold value for determination, and is a preset constant (value with a positive sign). If “|Ha|≧hx” and step S170 is affirmative, the process proceeds to step S180. If “|Ha|<hx” and step S170 is denied, vehicle deflection has not occurred (that is, not a single load state), and the process returns to step S110.

In step S180, the one-sided load index Kt is calculated based on the magnitude (absolute value) of the azimuth angle deviation Ha. The one-sided load index Kt is an index indicating the degree of the one-sided load state in which the load loaded on the vehicle is biased in the vehicle width direction. Therefore, the larger the absolute value of the one-sided load index Kt, the more easily the vehicle is deflected. The direction in which the vehicle is easily deflected is represented by the sign of the deviation Ha.

For example, as shown in block X180, the one-sided load index Kt is “−hx<Ha<hx (where the predetermined amount hx corresponds to the threshold value in step S170)” based on the calculation map Zkt. Is determined to be "0". That is, the load is not a single load but a uniformly loaded state. Then, according to the calculation map Zkt, if the deviation Ha is the value “−hx” or less, or if the deviation Ha is the value hx or more, it is determined that the one-sided load index Kt increases as the deviation Ha increases. In other words, the larger the deviation Ha is (absolute value), the larger the absolute value of the single-load index Kt is calculated. The positive and negative signs of the one-sided load index Kt indicate which of the left and right sides the load is biased. Therefore, the positive/negative sign of the single load index Kt corresponds to the positive/negative sign of the deviation Ha and indicates the deflection direction of the vehicle. It should be noted that the piece load index Kt is limited to a predetermined upper limit value ka and lower limit value “−ka”.

As described in the first and second combination examples (see (1) and (2) above), it is determined by the road direction Dd determined by the navigation system NV or the camera system KM and the steering angle Sa. The single load index Kt is calculated based on the result of comparison (difference in azimuth angle) Ha with the traveling direction Vd. For example, it is assumed that the traveling road of the vehicle is a straight road and the road direction Dd (the direction of the road ahead of the vehicle and the reference direction in which the vehicle should travel) is “0 (straight line)”. At this time, when the steering angle Sa is not “0 (the neutral position corresponding to straight running)” under the condition of “Ga≧gx”, the vehicle is deflected and the load is in the single load state. To be judged. That is, the steering operation member (steering wheel) SW is operated, and the vehicle turning is requested as the traveling direction Vd of the vehicle by "Sa≠0". Since the road direction Dd, which is the reference of the azimuth angle, is accurately determined based on the navigation system NV and the camera system KM, the unloaded state of the cargo (the unloaded index Kt) can be appropriately determined (calculated). ..

In addition, as described in the third combination example (see (3) above), the actual turning amount Ya (the actual yaw rate Yr, which corresponds to the “road direction Dd”) and the steering angle Sa are determined. The single load index Kt can be calculated based on the comparison result Ha with the reference turning amount Ys (corresponding to the “traveling direction Vd”). Similarly, it is assumed that the traveling road of the vehicle is a straight road. At this time, when the vehicle is deflected under the condition of “Ga≧gx”, the driver operates the steering operation member SW in order to drive the vehicle to travel straight. Therefore, although the actual yaw rate Yr (that is, the actual turning amount Ya and the road direction Dd) is “0 (the road direction Dd is a straight line)”, “Sa≠0” and the steering angle Sa is determined based on the steering angle Sa. When the calculated standard turning amount Ys (that is, the traveling direction Vd) is not "0", the vehicle deflection is compensated by the steering operation by the driver. In such a case, it is determined that the load is in a single load state, and the single load index Kt is calculated. The third combination example is slightly inferior to the first and second combination examples in terms of determination accuracy. However, it is possible to more easily determine the unloaded condition (unloaded index Kt) of the load.

<Automatic braking device JS using the single load index Kt>
With reference to the functional block diagram of FIG. 3, the process of automatic braking control using the single load index Kt in the automatic braking device JS will be described. The required deceleration Gs in the automatic braking control is calculated by the driving support controller ECJ. Then, the braking controller ECB controls the fluid unit HU (ML, UP, etc.) so as to adjust the braking hydraulic pressure Pw (that is, the braking torque Tq) of each wheel WH based on the required deceleration Gs. The result of each calculation process is shared via the communication bus BS, and can be calculated by any of the braking controller ECB, the driving support controller ECJ, and the navigation controller ECN. The controller ECU is a general term for the braking controller ECB, the driving support controller ECJ, and the navigation controller ECN.

The vehicle detects the distance (relative distance) Ob between the vehicle and an object (another vehicle, a fixed object, a bicycle, a person, an animal, etc.) existing ahead of the vehicle, and A distance sensor OB is provided. For example, a radar, a camera system KM, or the like is used as the distance sensor OB. When the fixed object is stored in the map information, the signal of the navigation system NV is used as the distance sensor OB. The detected relative distance Ob is input to the driving assistance controller ECJ. The driving support controller ECJ includes a collision margin time calculation block TC, a vehicle head time calculation block TW, and a required deceleration calculation block GS.

The collision margin time calculation block TC calculates the collision margin time Tc based on the relative distance Ob between the object in front of the vehicle and the host vehicle. The collision surplus time Tc is the time until the collision between the own vehicle and the object. Specifically, the collision margin time Tc is determined by dividing the relative distance Ob between the object in front of the vehicle and the host vehicle by the speed difference between the obstacle and the host vehicle (that is, the relative speed). It Here, the relative speed is calculated by time-differentiating the relative distance Ob.

In the vehicle head time calculation block TW, the vehicle head time Tw is calculated based on the relative distance Ob and the vehicle body speed Vx. The headway time Tw is the time until the vehicle reaches the current position of the object ahead. Specifically, the headway time Tw is calculated by dividing the relative distance Ob by the vehicle body speed Vx. When the object ahead of the host vehicle is stationary, the collision margin time Tc and the headway time Tw match. The vehicle speed Vx is acquired from the vehicle speed calculation block VX of the braking controller ECB via the communication bus BS.

In the required deceleration calculation block GS, the required deceleration Gs is calculated based on the collision margin time Tc and the headway time Tw. The required deceleration Gs is a target value of the deceleration of the host vehicle for avoiding a collision between the host vehicle and a front object. The required deceleration Gs is calculated according to the calculation map Zgs such that the larger the collision margin time Tc is, the smaller it is (or the smaller the collision margin time Tc is, the larger it is). Further, the required deceleration Gs can be adjusted based on the headway time Tw. The requested deceleration Gs is adjusted based on the vehicle head time Tw so that the requested deceleration Gs becomes smaller as the vehicle head time Tw becomes larger (or the requested deceleration Gs becomes larger as the vehicle head time Tw becomes smaller). .. The required deceleration Gs is input to the braking controller ECB via the communication bus BS.

Each wheel WH of the vehicle is provided with a wheel speed sensor VW so as to detect the rotation speed (wheel speed) Vw of the wheel WH. The detected wheel speed Vw is input to the braking controller ECB. The braking controller ECB includes a vehicle body speed calculation block VX, an actual deceleration calculation block GA, an automatic braking control block JC, and a drive circuit DR.

In the vehicle speed calculation block VX, the vehicle speed Vx is calculated based on the four wheel speeds Vw. The actual deceleration calculation block GA calculates the actual deceleration Ga based on the vehicle body speed Vx. Specifically, the vehicle speed Vx is time-differentiated to calculate the actual deceleration Ga. Further, the actual deceleration Ga may be determined based on the longitudinal acceleration (longitudinal deceleration) Gx. Further, the actual vehicle deceleration Ga may be calculated based on the differential value (calculated value) of the vehicle body speed Vx and the longitudinal acceleration Gx (detected value).

In the automatic braking control block JC, automatic braking control is executed based on the required deceleration Gs and the actual deceleration Ga. First, in the automatic braking control block JC, the necessity of automatic braking is determined. When the driver has already operated the braking operation member BP and the actual deceleration Ga is higher than the required deceleration Gs, the automatic braking control is not necessary. On the other hand, when the actual deceleration Ga is smaller than the required deceleration Gs, the feedback control (automatic braking control) based on the deceleration of the vehicle is executed so that the actual deceleration Ga matches the required deceleration Gs.

The automatic braking control block JC includes a single load index calculation block KT, a front/rear distribution ratio calculation block HX, a left/right distribution ratio calculation block HY, a target hydraulic pressure calculation block PT, and a drive signal calculation block DS.

As described with reference to the flow chart of FIG. 2, the single load index calculation block KT calculates the single load index Kt based on the deviation (azimuth angle deviation) Ha between the road direction Dd and the traveling direction Vd. It The single load index Kt is an index expressing the degree of the single load state of the load. As the one-sided load index Kt is larger, the load is unevenly loaded, and the vehicle is more likely to be deflected during automatic braking. In addition, on the basis of the sign of the one-sided load index Kt, it is identified which of the left and right sides of the load is biased, and the direction in which vehicle deflection is likely to occur is determined.

In the front-rear distribution ratio calculation block HX, the front-rear distribution ratio Hx is calculated based on the single load index Kt and the calculation map Zhx. The front-rear distribution ratio Hx is a distribution ratio between the front and rear wheels for allocating the total braking force Fv (target value) acting on the entire vehicle for achieving the required deceleration Gs to the braking force of the front and rear wheels WHf, WHr. .. Here, the front-rear distribution ratio Hx is a ratio with respect to the front two wheels WHf (front left and right wheels). Therefore, the ratio of the rear two wheels WHr (left and right rear wheels) is “1-Hx”.

The front-rear distribution ratio (ratio of the front two wheels WHf) Hx is calculated based on the calculation map Zhx to a value xo (a value of “0” or more) when the single load index Kt is less than the value kt. When the single load index Kt is greater than or equal to the value kt, the front-rear distribution ratio Hx is calculated to increase as the single load index Kt increases. The front-rear distribution ratio Hx is limited to the value xa (value equal to or less than "1"). Here, the value kt, the value xo, and the value xa are predetermined values set in advance for the calculation map Zhx. When the front/rear distribution ratio Hx is the predetermined value xo, the automatic braking control is not executed, and the front wheel and rear wheel braking hydraulic pressures Pwf and Pwr are increased by the operation of the braking operation member BP (referred to as “normal braking”). Correspond. Therefore, the case of "Hx=xo" is referred to as "common distribution ratio". The regular distribution ratio is set as a parameter of the braking device by the pressure receiving area of the wheel cylinder CW, the effective braking radius of the rotating member KT, the friction coefficient of the friction material, and the like.

During braking, the front wheel load increases and the rear wheel load decreases, so the front wheel WHf has a larger braking force generation capacity than the rear wheel WHr. In addition, increasing the braking force Ff of the front wheels WHf secures the rear wheel lateral force rather than increasing the braking force Fr of the rear wheels WHr, so that the effect of suppressing the vehicle deflection is higher. Therefore, the distribution ratio Hx for the front wheels WHf is set to be larger than the normal distribution ratio xo as the piece load index Kt is larger. As a result, the braking force Ff (target value) of the front wheels WHf is set large, and the braking force Fr (target value) of the rear wheels WHr is set small.

In the left/right distribution ratio calculation block HY, the left/right distribution ratio Hy is calculated based on the single load index Kt and the calculation map Zhy. The left/right distribution ratio Hy is between the left and right wheels for allocating the total braking force Fv of the vehicle for achieving the required deceleration Gs to the braking force for the left and right wheels (that is, the wheels located outside and inside with respect to the deflection direction). Is the distribution ratio of Here, the outer and inner wheels with respect to the deflection (turning) are set based on the sign of the single load index Kt. Specifically, when the vehicle is prone to be deflected to the left (that is, to the left), the single load index Kt is determined to be a positive sign. On the other hand, when the vehicle is easily deflected to the right (right turn), the single-load index Kt is determined to have a negative sign. The left/right distribution ratio Hy is a ratio of front and rear wheels on the outside of turning (deflection outside), and a ratio of front and rear wheels on the inside of turning (deflection inside) is “1-Hy”.

The left-right distribution ratio (outer front-rear wheel ratio) Hy is calculated based on the calculation map Zhy so that the left-right distribution ratio Hy increases as the single load index Kt increases. When “Kt=0” and the load is uniform, “Hy=0.5” is determined, and the same braking force is generated at the left and right wheels (that is, automatic braking control is not executed). If normal distribution ratio). Then, based on the left/right distribution ratio Hy, the braking force (target value) of the deflection outer wheel is increased and the braking force (target value) of the deflection inner wheel is decreased. In addition, the larger the magnitude (absolute value) of the left/right distribution ratio Hy, the larger the difference between the left and right braking forces. A yaw moment is generated due to the left-right difference of the braking force, and the deflection can be effectively suppressed.

In the target hydraulic pressure calculation block PT, the target braking force Fw of each wheel WH is calculated based on the total braking force (total braking force acting on the vehicle) Fv, the left/right distribution ratio Hy, and the front/rear distribution ratio Hx. It Specifically, the total braking force Fv is calculated based on the required deceleration Gs. Then, the total braking force Fv is distributed to the braking force (target value) Fw of each wheel WH based on the front-rear distribution ratio Hx and the left-right distribution ratio Hy. For example, the target braking force Fwfs of the outer front wheel is “Fwfs=Fv×Hx×Hy”, the target braking force Fwrs of the outer rear wheel is “Fwrs=Fv×(1-Hx)×Hy”, the target control force of the inner front wheel. The power Fwfu is “Fwfu=Fv×Hx×(1-Hy)”, and the target braking force Fwru of the inner rear wheel is “Fwru=Fv×(1-Hx)×(1-Hy)”. Is calculated. It should be noted that one of the front-rear distribution and the left-right distribution of the braking force described above can be omitted. In other words, with respect to the braking torque (result, braking force), at least one of the front-rear distribution and the left-right distribution is performed based on the single load index Kt (characteristic value indicating the degree of single load).

In the target hydraulic pressure calculation block PT, the target hydraulic pressure Pt is calculated for each wheel WH based on the target braking force Fw. Since the specifications of the braking device (the effective braking radius of the rotating member KT, the friction coefficient of the friction material, the pressure receiving area of the wheel cylinder CW, etc.) are known, the target braking force Fw is converted into hydraulic pressure, and the target hydraulic pressure is converted. Pt is determined.

In the drive signal calculation block DS, the motor drive signal Ml, the pressure regulating valve drive signal Up, and the inlet valve/outlet valve drive signals Vi, Vo are calculated. For example, based on the target hydraulic pressure Pt, the drive signal Ml (current instruction value) that indicates the amount of electricity (current value) to the electric motor ML is calculated. Further, the drive signals Up, Vi, Vo of the solenoid valve are determined based on the target hydraulic pressure Pt. In the drive circuit DR, the electric motor ML and the solenoid valves UP, VI, VO are controlled so that the braking force Fw of each wheel is achieved based on the drive signals Ml, Up, Vi, Vo.

<Other Embodiments>
Hereinafter, other embodiments will be described. In other embodiments, the same effect as above can be obtained. That is, the single load state is determined with high accuracy, and the braking force (the braking fluid pressure Pw) of each wheel that acts on the vehicle is determined based on the determination result (single load index) Kt. At least one of the front-rear distribution ratio Hx of the total braking force) Fv and the left-right distribution ratio Hy is preferably adjusted. Therefore, the vehicle deflection due to the one-sided load can be efficiently suppressed.

In the above embodiment, the front-back type is illustrated as the two-system fluid path. Alternatively, a diagonal fluid path (also referred to as "X-type") configuration may be employed. In the diagonal type fluid passage, one of the two hydraulic chambers of the master cylinder CM is connected to the wheel cylinders CWi and CWl, and the other side is connected to the wheel cylinders CWj and CWk.

In the above-described embodiment, as the device that applies the braking torque (resultingly, the braking force) to the wheels WH, a hydraulic type device via the braking liquid BF is illustrated. Alternatively, an electric type driven by an electric motor may be adopted. In the electric device, the rotary power of the electric motor is converted into linear power, and the friction member is pressed against the rotary member KT. Therefore, the braking torque Tq is directly applied by the electric motor irrespective of the braking fluid pressure Pw, and the braking force is generated. Further, it may be a composite type in which a hydraulic type through the braking fluid BF is adopted for the front wheels, and an electric type is adopted for the rear wheels.

Claims

A load determination device for a vehicle that determines a load condition in which a load loaded on the vehicle is biased in the vehicle width direction,
First direction acquisition means for acquiring a road direction in which the vehicle is traveling,
Second direction acquisition means for acquiring the traveling direction of the vehicle,
When the deceleration of the vehicle is equal to or greater than a predetermined value, a controller that determines that the vehicle is in the single-load state based on a deviation between the road direction and the traveling direction,
A single load determination device for a vehicle, comprising:
The single load determination device for a vehicle according to claim 1,
The first direction acquisition means is a global positioning system and a navigation system having map information,
The second direction acquisition means is a steering angle sensor that detects a steering angle of the vehicle,
The controller is
Determining the road direction by associating the position of the vehicle obtained by the global positioning system with the map information,
A single load determination device for a vehicle, which calculates the traveling direction based on the steering angle.
The single load determination device for a vehicle according to claim 1,
The first direction acquisition means is a camera system for photographing the front of the vehicle,
The second direction acquisition means is a steering angle sensor that detects a steering angle of the vehicle,
The controller is
Determining the road direction based on the image of the camera system,
A single load determination device for a vehicle, which calculates the traveling direction based on the steering angle.
An automatic braking device for a vehicle, comprising the single load determination device for the vehicle according to any one of claims 1 to 3, which suppresses a collision with an object in front of the vehicle,
The controller is
Compute a single load index that is the determination result of the single load state,
An automatic braking device for a vehicle, which adjusts at least one of a front-rear distribution ratio of a braking force acting on the vehicle and a left-right distribution ratio of a braking force acting on the vehicle based on the one-sided load index.