JP3562501B2 - Vehicle motion control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the traveling stability of a vehicle in a good condition even when the deviation of the actual yawing momentum to the target yawing momentum is particularly large. SOLUTION: A slide slip angle change speed β' of a center-of-gravity point as the actual yawing momentum of a vehicle having plural wheels is gained (S5), and the brake fluid pressure ΔP is acted on one of brakes of left and right rear wheels when an absolute value of the change speed β' is more than a predetermined value β0', to produce the yawing moment in a state that the more the absolute value of the change speed β' is, the more a value is, in the direction to reduce the absolute value of the change speed β' (S10-S12). Even during the control of the yawing moment, discrimination whether the slip control is necessary or not on the wheel applied the brake fluid pressure ΔP, continues (S1) and when the slip control is necessary the slip control for keeping a slip ratio within a proper range is executed by controlling the brake fluid pressure ΔP.

Description

[0001]
[Industrial applications]
The present invention relates to a vehicle motion control device that controls yawing motion of a vehicle.
[0002]
[Prior art]
The present applicant has previously proposed and applied for the following as one of the vehicle motion control devices of the above type. This is a vehicle motion control device described in the specification of Japanese Patent Application No. 2-326616 (Japanese Patent Application Laid-Open No. 4-193658). The actual yaw motion state quantity of a vehicle is defined as a vehicle body side slip angle at a vehicle center of gravity. This is to detect and control the yawing moment of the vehicle based on the detection. In this specification, as one embodiment of the invention, a vehicle motion control that mounts a Doppler speed sensor on a vehicle in each of a front-rear direction and a lateral direction thereof and detects a vehicle body side slip angle based on output signals from both of them. An apparatus is described.
[0003]
[Problems to be solved by the invention]
In this way, if the yawing moment of the vehicle is controlled such that the actual yaw motion state quantity such as the vehicle body slip angle approaches the target yaw motion state quantity, generally the running stability of the vehicle can be improved. However, it has been found that when the deviation of the actual yaw motion state quantity from the target yaw motion state quantity is particularly large, it may not always be desirable to apply a braking force to the wheels to completely eliminate the deviation.
[0004]
[Means, actions and effects for solving the problem]
In view of this fact, it is an object of the present invention to keep the running stability of a vehicle as good as possible even when the deviation of the actual yaw motion state quantity from the target yaw motion state quantity is particularly large. It was done as. As a result, the vehicle motion control device described below was obtained.
[0005]
(1) The actual yawing motion state of the vehicle having a plurality of wheels is given to the vehicle by applying a braking force to at least one of the plurality of wheels according to a deviation of the actual yawing motion state quantity from the target yawing motion state quantity. A yaw moment generating section that performs yaw control for generating a yaw moment that brings the amount closer to the target yaw movement state amount;
A braking force applying unit for performing vehicle braking for applying a braking force according to an operation of a brake operating member to the plurality of wheels,
Proper range maintaining means for controlling a braking force of the at least one wheel to maintain a slip ratio of the wheel within a proper range;
A vehicle speed sensor for detecting a running speed of the vehicle body;
A wheel speed sensor for detecting a rotation speed of the at least one wheel;
Based on the detection results of the vehicle speed sensor and the wheel speed sensor, it is determined whether or not control for maintaining the actual slip ratio in an appropriate range is required for the at least one wheel, and there is no need for slip control.DeterminedIn this case, it is necessary to generate a yawing moment that causes the actual yawing motion state quantity to approach the target yawing motion state quantity in the yawing moment generating unit, and thus it is necessary to perform slip control.DeterminedIn this case, the yaw moment generating section does not generate a yaw moment that brings the actual yaw movement state amount close to the target yaw movement state amount, and the appropriate range maintaining means controls the slip ratio of the at least one wheel to an appropriate range. Judgment and control means to maintain
And, even if the vehicle braking is required after the yaw control is started, even if the yaw control is required after the vehicle braking is started, the yaw control and the vehicle braking are performed in parallel. Vehicle motion control device to be performed (Claim 1).

[0006]
The yawing moment generator is generally configured to generate a yawing moment by controlling at least one of the magnitude and direction of a plane force generated between the left and right wheels of the vehicle and the road surface. Among them, for example, a driving / braking force left / right difference control type that makes the left and right wheels (the resultant force of the driving force and the braking force) generated between the left and right wheels and the road surface different from each other, There is a drive / braking force front / rear distribution control type in which the front / rear force generated between the front and rear wheels is different between front and rear, and the present invention can be applied to these.
[0007]
In any case, by applying a braking force to at least one of the plurality of wheels, a yawing moment can be generated in the vehicle, and the wheel to which the braking force is applied and the magnitude of the braking force to be applied are appropriately selected. By doing so, the actual yaw motion state quantity of the vehicle can be made closer to the target yaw motion state quantity. However, if the yawing moment to be generated is large, the braking force to be applied becomes large, and the slip of the wheel to which the braking force is applied becomes excessive, and the running stability of the vehicle is rather reduced. There is.
[0008]
On the other hand, in the vehicle motion control device according to the present invention, even when the yawing moment generating unit is generating the yawing moment, the slip ratio of the wheel to which the braking force is applied deviates from the appropriate range. Since this is prevented by the control unit, the actual yaw motion state quantity is brought close to the target yaw motion state quantity in a range where the wheel slip does not become excessive, and the running stability of the vehicle is improved satisfactorily.
[0009]
(2) The yawing moment generating section includes:
Control amount determining means for determining a control amount according to a deviation of the actual yawing motion state amount from the target yawing motion state amount,
The braking force according to the control amount determined by the control amount determining unitOn said at least one wheelBraking force applying means for applying;
The vehicle motion control apparatus according to the above mode (1) (Claim 2).
The control amount determining means determines a control amount according to a deviation of the actual yawing movement state amount from the target yawing movement state amount, and the braking force applying means determines a braking force according to the determined control amount.At least oneSince the actual yawing motion state amount is quickly and appropriately approximated to the target yawing motion state amount, the wheel amount is applied to the wheels.
[0010]
(3) The aboveThe judgment / control means isIn a state where the yawing moment generating section is generating the yawing moment, it is necessary to perform control to maintain the actual slip ratio of the wheel to which the braking force is applied in an appropriate range.Judge,There is a need for slip controlIn the case, the appropriate range maintaining means,By suppressing the braking force of the wheel to which the braking force is applied, the slip ratio of the wheel is maintained within the appropriate range.Is to let The vehicle motion control device according to (1) or (2) (Claim 3).
The judgment / control means isIt is determined that the wheel to which braking force is applied needs slip controlIf you doAppropriate range maintaining meansToReduces braking forceLetMaintain the slip rate within an appropriate rangeLet it.
[0011]
(4) The yawing moment generatorBut,
carA lateral acceleration sensor that detects acceleration in the vehicle lateral direction at both gravity points;
A yaw rate sensor for detecting a yaw rate of the vehicle body,
The vehicle body slip angle change speed at the center point of the vehicle weight, which is a value obtained by subtracting the detected yaw rate detected by the yaw rate sensor from the value obtained by dividing the detected lateral acceleration detected by the lateral acceleration sensor by the detected vehicle speed detected by the vehicle speed sensor. Yaw moment control means for controlling the yaw moment of the vehicle based on
The vehicle motion control device according to any one of (1) to (3) (Claim 4).
(5) The yawing moment control means generates a yawing moment in such a direction that the larger the absolute value of the vehicle body slip angle change speed is, the larger the value is and the absolute value of the vehicle body slip angle change speed is reduced. The vehicle motion control device according to the paragraph.
(6) The yawing moment generator controls the yawing moment based on not only the vehicle body slip angle changing speed at the vehicle center point but also the vehicle body slip angle at the vehicle center point.(Four) Term or (Five) TermA vehicle motion control device according to claim 1.
[0012]
As the yaw movement state quantity of the vehicle, for example, a vehicle body side slip angle β and a vehicle body side slip angle change speed β ′ at the vehicle center of gravity can be used. In a normal turning motion of the vehicle, the vehicle body slip angle β at the vehicle center of gravity (clockwise is positive.FIG.reference. See also the figure for other vehicle motion state quantities. ) Is approximately 0 and can be considered to be significantly smaller than 1 (radian). Therefore, the vehicle body slip angle β is equal to the vehicle body longitudinal velocity v_x(Positive forward) and lateral velocity v_y(Positive in the right direction) and can be expressed as follows.
β ≒ v_y/ V_x
[0013]
On the other hand, the vehicle speed V is usually the vehicle front-rear speed v_xAnd lateral speed v_yIn this case, since the vehicle body slip angle β is considered to be almost 0, the longitudinal velocity v_xCan be regarded as approximately equal to Therefore, the vehicle body slip angle β is determined by the vehicle speed V and the lateral speed v._yAnd can be expressed as follows.
β ≒ v_y/ V
[0014]
In a normal turning motion having such a relationship, a lateral acceleration G, which is an acceleration of the vehicle weight center point in the vehicle lateral direction, is given._y(Positive in the left direction) is expressed by the following equation (hereinafter referred to as a side slip motion equation) regardless of whether the tire characteristic, which is the relationship between the wheel slip angle and the cornering power, is in a linear region or a non-linear region. It is already known that
G_y= V_y'+ V · γ
However, here, "v_y′ ”Is the lateral velocity v_yMeans the time differential value, and “γ” means the yaw rate of the vehicle body (clockwise is positive). The following equation is obtained by transforming this equation of side slip motion using the above equation.
β '= G_y/ V-γ
Here, “β ′” means a time differential value of the vehicle body slip angle β, that is, “the vehicle body slip angle change speed at the vehicle center of gravity” in the present invention.
[0015]
In view of these circumstances, in the vehicle motion control device according to the preferred embodiment of the present invention, the lateral acceleration G_yIs divided by the vehicle speed V to subtract the yaw rate γ, and the yawing moment is controlled based on the vehicle body slip angle change speed β ′. For example, the yawing moment is controlled so as to decrease the absolute value of the vehicle body slip angle change speed β ′ by using the above-described drive / braking force left / right difference control, drive / braking force front-rear distribution control, and the like.
[0016]
In particular, if the yaw motion state quantity is the vehicle body slip angle change speed at the center of gravity of the vehicle, it can be detected using a low-cost and highly reliable lateral acceleration sensor, vehicle speed sensor, and yaw rate sensor. In addition, the effect that the reliability can be improved can be obtained.
[0017]
Further, since the vehicle body slip angle change speed can be detected without differentiating the output signals from these sensors with respect to time, the vehicle body slip angle change speed can be accurately detected without being significantly affected by the noise of the output signal. The effect of being able to do so is also obtained.
[0018]
In addition, since the vehicle body slippage equation of motion is detected using the fact that the tire slip equation of motion is established regardless of whether the tire characteristics are in a linear region or a non-linear region, the actual tire characteristics are linear. There is also obtained an effect that the yawing motion can be appropriately controlled regardless of whether it is in the area or the non-linear area.
[0019]
Furthermore, since the yawing motion state amount is not detected as the vehicle body side slip angle as in the vehicle motion control device described in the above-mentioned specification, but is detected as the vehicle body side slip angle change speed, the change of the yawing motion state amount is not detected. Detection can be performed quickly, and the control response to a change in the amount of yawing motion can be easily accelerated.
[0020]
【Example】
Hereinafter, a vehicle motion control device according to an embodiment of the present invention will be described in detail with reference to the drawings. The vehicle motion control device mainly includes a brake system 8, and the brake system 8 is provided in a vehicle having left and right front wheels 10 and left and right rear wheels 12, as shown in FIG. . The front wheels 10 are turned in response to the operation of a steering wheel (not shown), and the rear wheels 12 are driven by an engine and a transmission (not shown). This vehicle is capable of controlling the rear wheel steering angle, and is provided with a rear wheel actuator 20 for changing the rear wheel steering angle and a rear wheel steering angle controller 22 for controlling the same. The rear wheel steering angle controller 22 controls the rear wheel steering angle via the rear wheel actuator 20 so that the vehicle side slip angle β at the vehicle center of gravity always becomes substantially zero. Is well known and is not indispensable for understanding the present invention, so that the detailed description is omitted.
[0021]
The configuration of the brake system 8 will be described with reference to FIG.
The brake system 8 includes brakes 30 provided on the left and right front wheels 10 (indicated by “FL” and “FR” in the figure) and the left and right rear wheels 12 (indicated by “RL” and “RR” in the figure). The brake pressure is generated by an electric / manual system, and the brake pressure is always generated electrically by the electric hydraulic pressure generator 38. However, if the brake pressure becomes abnormal, the master cylinder 42 mechanically generates the brake pressure. To generate brake pressure.
[0022]
The electric hydraulic pressure generating device 38 monitors the pressure of each brake 30 via each pressure sensor 46 while controlling the high brake pressure stored in the accumulator 54.Is reduced by an electromagnetic proportional control valve (hereinafter, simply referred to as a control valve) 58, and the pressure of each brake 30 is controlled.Each control valve 58 is controlled by a brake controller described later. The accumulator 54 is provided with a pressure switch 59 that operates in accordance with the pressure of the accumulator 54. The pump IC 60 controls the pump 61 based on an electric signal from the accumulator 54, so that the accumulator 54 always accumulates brake pressure in a certain range. It is supposed to be.
[0023]
The selection between the electric system and the manual system is made by a plurality of electromagnetic directional switching valves (hereinafter simply referred to as switching valves) 62 and 64. More specifically, the switching valves 62 and 64 are always at the original positions shown in the figure and connect the master cylinder 42 to the respective brakes 30. However, when it is necessary to make the electric system effective, the switching valves 62 and 64 are used. , 64 are energized all at once to disconnect each brake 30 from the master cylinder 42 and communicate with each control valve 58. On the other hand, it is necessary to invalidate the electric system and activate the manual system due to an abnormality in the electric system. In some cases, the switching valves 62 and 64 are simultaneously demagnetized and returned to the original state. The switching valves 62 and 64 are also controlled by a brake controller described later.
[0024]
When the electric system is enabled, the master cylinder 42 is connected to each stroke simulator 70 by each switching valve 62. Each stroke simulator 70 simulates a stroke feeling of the brake pedal 34 by absorbing the brake fluid discharged from the master cylinder 42 under pressure.
[0025]
The master cylinder 42 is of a tandem type having two independent pressurizing chambers in series, and the brake pressure generated in one pressurizing chamber is applied to each brake 30 of the left and right front wheels 10 and to the other pressurizing chamber. Is transmitted to the brakes 30 of the left and right rear wheels 12, respectively. A proportioning valve 74 is connected between the switching valves 62 and 64 to the brake system on the rear wheel side.
[0026]
The brake controller 80 is mainly configured by a computer including a CPU 90, a ROM 92, a RAM 94, a bus 96, an input unit 98, and an output unit 100. The input unit 98 includes a pedaling force sensor 104 for detecting the pedaling force F of the brake pedal 34, a brake switch 106 for detecting the depression of the brake pedal 34, the pressure sensors 46, and the wheels for detecting the wheel speeds of the wheels 10 and 12. Speed sensor 110, lateral acceleration G at vehicle center of gravity_y, A vehicle speed sensor 114 for detecting the vehicle speed V, a yaw rate sensor 116 for detecting the yaw rate γ of the vehicle body, and the like. On the other hand, the control valve 58 and the switching valves 62 and 64 are connected to the output unit 100.
[0027]
As shown in FIG. 4, the lateral acceleration sensor 112 sets the lateral acceleration G assuming that the left direction is positive and the right direction is negative._yThe yaw rate sensor 116 detects the yaw rate γ with the clockwise direction being positive and the counterclockwise direction being negative.
[0028]
The ROM 92 stores various programs including a brake control routine shown in the flowchart of FIG. 1. The CPU 90 periodically executes the brake control routine to control the brake pressure of each wheel 10, 12. Control. It should be noted that the flow chart in FIG. 4 shows that the brake pressure of all the wheels 10 and 12 is simultaneously controlled by one execution of one brake control routine common to all the wheels 10 and 12. This is merely to simplify the flowchart. In practice, a brake control routine is provided for each wheel 10, 12 and the CPU 90 By sequentially executing the brake control routine, the brake pressure of each of the wheels 10 and 12 is sequentially controlled. However, the following description of the brake control routine will be made in accordance with the simplified flowchart.
[0029]
The brake control routine generally describes the pedaling force F and the vehicle body slip angle β (clockwise) while controlling the brake pressure of each wheel 10, 12 so as not to cause an excessive slip on each wheel 10, 12. Are positive, and the counterclockwise direction is negative. Refer to FIG. 4) to control each brake pressure based on the vehicle body slip angle change speed β ′. The actual slip ratio of each wheel 10, 12 is always kept in a stable region to the left of the peak point of the μ-S curve.
[0030]
By the way, since the rear wheel steering angle control can be performed on the vehicle provided with the brake system 8 by the rear wheel steering angle controller 22, the vehicle should normally have a vehicle body side slip angle β greatly deviating from 0. Nothing should change or change suddenly. The rear wheel steering angle control controls the rear wheel steering angle based on the fact that the cornering power of the rear wheel 12 increases as the wheel slip angle of the rear wheel 12 (hereinafter, simply referred to as rear wheel slip angle) increases. However, such a relationship does not hold in the entire rear wheel slip angle, but only in a region where the rear wheel slip angle is small.When the rear wheel slip angle increases to a certain extent, the cornering power hardly increases and further increases. Then it will decrease. Therefore, the rear wheel steering angle control alone cannot sufficiently control the yawing motion of the vehicle in a region where the rear wheel slip angle is large.
[0031]
In view of such circumstances, in the present embodiment, in a state where the rear wheel steering angle control has reached the limit and the yawing motion of the vehicle cannot be controlled adequately, the braking force of the left and right rear wheels 12 is controlled by the left and right. For the purpose of appropriately controlling the yawing motion by making it different, whether the rear wheel steering angle control has reached the limit or not is determined by the absolute value of the vehicle body side slip angle change speed β 'is a threshold value β'.₀(> 0) is determined indirectly by determining whether or not it is greater than or equal to. When the limit is reached, a left-right difference is generated in the braking force of the left and right rear wheels 12 in addition to the rear wheel steering angle control. By performing the braking force left / right difference control, a sudden change in the absolute value of the vehicle body side slip angle β is prevented, and the yawing motion of the vehicle is appropriately controlled. Excessive yawing motion, which could not be suppressed by the rear wheel steering angle control, is suppressed by generating a yawing moment due to the left-right difference between the braking forces of the left and right rear wheels 12 in the opposite direction. The yaw motion of the vehicle is always made appropriate by complementing the angle control.
[0032]
It should be noted that even when the rear wheel steering angle control does not reach the limit, the vehicle body side slip angle change speed β ′ is equal to the threshold β ′.₀This may be the case. For example, the case where the rear wheel steering angle controller 22 or the like breaks down or the case where the steering wheel is not broken down but the steering speed of the steering wheel is too fast in relation to the ability of the wheel steering angle control thereafter. In this embodiment, the braking force left / right difference control is similarly performed in this case to prevent a sudden change in the vehicle body slip angle β.
[0033]
That is, in the present embodiment, the braking force left / right difference control for controlling only the braking force among the driving force and the braking force generated between each rear wheel 12 and the road surface is an example of the driving / braking force left / right difference control. Is used to control the yawing moment.
[0034]
The brake control routine will be described in detail with reference to FIG.
When executing this routine each time, first, in step S1 (hereinafter simply referred to as S1; the same applies to other steps), the brake switch 106 and the wheel speed sensor110It is determined whether or not slip control (that is, control for maintaining the actual slip ratio of each wheel 10, 12 in an appropriate range) is necessary based on the electric signal from the above. Assuming that it is not necessary this time, the determination is NO, the pedaling force F is read from the pedaling force sensor 104 in S2, and the lateral acceleration G from the lateral acceleration sensor 112, the vehicle speed sensor 114, and the yaw rate sensor 116 in S3._y, The vehicle speed V and the yaw rate γ are read, and then, in S4, the threshold value β ′ of the vehicle body slip angle change speed β ′₀(> 0) and a later-described proportional coefficient K (> 0) are determined according to the vehicle speed V, respectively. Note that these thresholds β ′₀The relationship between each of the proportional coefficients K and the vehicle speed V is stored in the ROM 92 in advance.
[0035]
Thereafter, in S5, the lateral acceleration G_yIs divided by the vehicle speed V to subtract the yaw rate γ to calculate the vehicle body slip angle change speed β ′.₀It is determined whether or not this is the case. Assuming that this time is not the case this time, the determination is NO, and in S7, the increase ΔP in the brake pressure of the left rear wheel 12_RLIs also the increment ΔP of the brake pressure of the right rear wheel 12._RRIs also set to 0. Subsequently, in S8, a target value P of the brake pressure of each of the wheels 10, 12 is calculated according to the pedaling force F, and for each of the left and right front wheels 10, it is set as the final target brake pressure as it is. For each of the rear wheels 12, the calculated target value P and the increment ΔP_RLAnd ΔP_RRIs the final target brake pressure. In this step, an electric signal is output to each control valve 58 so that the target brake pressure of each of the wheels 10 and 12 is realized. This time, the increment ΔP_RLAlso ΔP_RRIs also zero, so that a brake pressure having a height corresponding to only the pedaling force F is generated. Thus, one execution of this routine ends.
[0036]
On the other hand, in this case, excessive driving force is applied to the wheels 10 and 12 in relation to the road surface friction coefficient when the vehicle is driven, or excessively large in relation to the road surface friction coefficient during vehicle braking. Assuming that the braking force is applied to the wheels 10 and 12, it is determined in S1 that the slip control of the wheels 10 and 12 needs to be performed, and the determination in this step is YES. Instead of executing the steps after S2, the slip control is performed on the corresponding wheels 10, 12 in S9. Since this routine is executed on a regular basis, the actual slip ratio of all four wheels 10 and 12 is always maintained in an appropriate range.
[0037]
In this case, although the slip control is not necessary, the absolute value of the vehicle body slip angle change speed β ′ is equal to the threshold value β ′₀Assuming that this is the case, the determination in S1 is NO, the determination in S6 is YES, and in S10, whether the vehicle body slip angle change speed β 'is greater than 0, that is, with a positive value It is determined whether there is. Assuming this is the case this time, the determination is YES, and in S11, the increment ΔP of each rear wheel 12_RL, ΔP_RRAre respectively determined. In this case, it is assumed that the vehicle body slip angle change speed β 'is a positive value, which means that the actual yawing moment is rapidly increasing in the clockwise direction at present. This ultimately means a left-right difference in the front-rear force of the left and right rear wheels 12), and it is necessary to generate a counterclockwise yawing moment. Therefore, ΔP of the left rear wheel 12_RLIs the threshold value β 'from the body slip angle change speed β'₀Is calculated as a product of the proportional coefficient K and the increment ΔP of the right rear wheel 12._RRIs set to 0. Then, the process proceeds to S8. When the actual yawing moment is sharply increased in the clockwise direction, for example, as shown in FIG. 4, the wheel front-rear force of the left rear wheel 12 is larger than the wheel front-rear force of the right rear wheel 12 by an increment ΔP_RLIs increased in the direction opposite to the traveling direction of the vehicle only by the force based on.
[0038]
On the other hand, assuming that the vehicle body slip angle change speed β 'is a negative value this time, the determination in S10 is NO, and in S12, contrary to the above case, the braking force In order to generate a clockwise yawing moment due to the left-right difference, an increment ΔP of the left rear wheel 12 is set._RLIs 0, the increment ΔP of the right rear wheel 12_RRIs the threshold value β ′ from the vehicle side slip angle change speed β ′ (however, the sign is inverted).₀Is multiplied by the proportional coefficient K. Then, the process proceeds to S8.
[0039]
In this embodiment, since the actual slip ratios of the wheels 10 and 12 are controlled so as to be always in the stable region, if the brake pressure of the wheels 10 and 12 is increased, the control of the wheels 10 and 12 is performed. The power is also guaranteed to increase, and thus the generation of a yawing moment that suppresses excessive yawing movement is guaranteed.
[0040]
However, if there is a possibility that an excessive slip may occur in each of the wheels 10 and 12 as a result of increasing the brake pressure to generate such a yawing moment, the increase in the brake pressure is suppressed by the slip control in S9. Therefore, in this case, no yawing moment suitable for suppressing excessive yawing motion is generated.
[0041]
As is apparent from the above description, in the present embodiment, if the vehicle body slip angle β tends to change suddenly, the difference between the left and right braking forces of the left and right rear wheels 12 is controlled so as to suppress the tendency. This suppresses sudden changes in the vehicle body slip angle β and suppresses the occurrence of spin or drift-out, thereby suppressing a decrease in the running stability of the vehicle and preventing the driver from feeling uneasy while turning the vehicle. can do.
[0042]
Although it is possible to implement the present invention by performing the braking force left / right difference control alone and not with the rear wheel steering angle control, in the present embodiment, the braking force left / right difference control is performed together with the rear wheel steering angle control. This complements the rear wheel steering angle control. Therefore, in the present embodiment, the braking force left / right difference control is not performed as frequently as the case where the braking force left / right difference control is performed without the rear wheel steering angle control, and the early wear of the brake 30 does not need to be concerned. Specific effects can be obtained.
[0043]
Further, in the present embodiment, the appropriate yawing moment is generated by increasing the braking force of one of the left and right rear wheels 12 from a normal value, so that the vehicle speed is increased with the increase in the braking force. As V decreases, a unique effect that the vehicle traveling state is shifted to a stable side without brake operation is also obtained.
[0044]
Further, in the present embodiment, the brake pressure control for the braking force left / right difference control is electrically performed, and the brake pressure based on the braking force left / right difference control and the brake pressure based on the depression of the brake pedal 34 (that is, The braking pressure is based on the driver's intention. Therefore, there is a unique effect that the braking force left / right difference control can be performed without any trouble during the braking force left / right difference control and vice versa. Can be
[0045]
As is clear from the above description, in this embodiment,The brake system 8 constitutes a “braking force application unit”. Also,The part of the brake controller 80 that executes S3 to S6, S8, and S10 to S12 of the brake control routine of FIG. 1 constitutes a “control amount determining unit” in the present invention, and the brake system 8 performs “braking force application”. Means "together form a" yawing moment generator ".further,The part of the brake controller 80 that executes S1 of the brake control routine of FIG.Judgment / control meansAnd the part that executes S9 constitutes the “appropriate range maintaining means”, and they together constitute the “slip control unit”.

[0046]
As mentioned above, although one Example of this invention was described in detail based on drawing, this invention can be implemented also in another aspect.
[0047]
For example, in the above-described embodiment, an appropriate yawing moment is generated by increasing the brake pressure of only one of the left and right rear wheels 12 from a normal value. An appropriate yawing moment can be generated by changing the brake pressure in the opposite direction by the same amount from the normal value.
[0048]
Further, in the above-described embodiment, an appropriate yawing moment is generated by generating a left-right difference in the braking force between the left and right rear wheels 12, but, for example, a left-right difference in the braking force is generated between the left and right front wheels 10. By doing so, an appropriate yawing moment can be generated.
[0049]
Further, in the above-described embodiment, an appropriate yawing moment is generated by the left-right difference control of the braking force of the left and right rear wheels 12 as the driving wheels. However, for example, the right-left difference control of the driving force or An appropriate yawing moment can be generated in cooperation with the left / right difference control of the braking force.
[0050]
In the above-described embodiment, the brake pressure is always generated electrically. However, for example, it is necessary to always generate the brake pressure by the master cylinder 42 and perform the braking force left / right difference control. The brake pressure may be generated electrically only when.
[0051]
Further, in the above-described embodiment, the yawing moment is controlled based on the vehicle body slip angle change speed β ′ and the vehicle speed V. However, other parameters, for example, the vehicle body slip angle β (for example, The yawing moment can also be controlled on the basis of the vehicle body slip angle change speed β ′.
[0052]
Further, in the above-described embodiment, the yaw rate sensor 116 dedicated to the detection of the yaw rate γ is provided. For example, the yaw rate γ is determined by using the wheel speed sensors 110 of the left and right front wheels 10 and using the difference between the wheel speeds. It is also possible to detect indirectly. The same applies to the vehicle speed sensor 114. For example, it is possible to indirectly detect the vehicle speed V by diverting the plurality of wheel speed sensors 110 and estimating the vehicle speed V using the wheel speeds.
[0053]
In addition to these, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a brake control routine of a brake system which is a main component of a vehicle motion control device according to one embodiment of the present invention.
FIG. 2 is a plan view conceptually showing a configuration of a vehicle provided with the vehicle motion control device.
FIG. 3 is a system diagram showing a configuration of the brake system.
FIG. 4 shows lateral acceleration G_y, Vehicle speed V, yaw rate γ and vehicle body side slip angle β.
[Explanation of symbols]
8 Brake system
80 Brake controller
112 lateral acceleration sensor
114 Vehicle speed sensor
116 Yaw rate sensor

Claims (4)

By applying a braking force to at least one of the plurality of wheels according to a deviation of the actual yawing motion amount of the vehicle having a plurality of wheels from the target yawing motion amount, the actual yawing motion amount of the vehicle is set to the target. A yawing moment generator that performs yaw control for generating a yawing moment that approaches the yawing motion state quantity;
A braking force applying unit for performing vehicle braking for applying a braking force according to an operation of a brake operating member to the plurality of wheels,
Proper range maintaining means for controlling a braking force of the at least one wheel to maintain a slip ratio of the wheel within a proper range;
A vehicle speed sensor for detecting a running speed of the vehicle body;
A wheel speed sensor for detecting a rotation speed of the at least one wheel;
Based on the detection results of the vehicle speed sensor and the wheel speed sensor, it is determined whether or not control for maintaining the actual slip ratio in an appropriate range is required for the at least one wheel, and there is no need for slip control. When it is determined that the yawing moment is generated in the yawing moment generating section to bring the actual yawing motion state amount closer to the target yawing movement state amount, and when it is determined that there is a need for the slip control, the yawing moment generation is performed. Determining / controlling means for causing the proper range maintaining means to maintain the slip ratio of the at least one wheel within a proper range without generating a yawing moment for bringing the actual yawing motion state quantity close to the target yawing motion state quantity; And the vehicle braking after the yaw control is started Also become necessary, even if the required yaw control after the vehicle braking has been initiated, the vehicle motion control apparatus and their yaw control and vehicle braking is performed in parallel. The yawing moment generating section,
Control amount determining means for determining a control amount according to a deviation of the actual yawing motion state amount from the target yawing motion state amount,
Braking force applying means for applying a braking force according to the control amount determined by the control amount determining unit to the at least one wheel;
The vehicle motion control device according to claim 1, comprising: In the state where the yawing moment generating section is generating the yawing moment, the determination / control means needs control to maintain the actual slip ratio of the wheel to which the braking force is applied in an appropriate range. If there is a need for slip control, the appropriate range maintaining means suppresses the braking force of the wheel to which the braking force is applied, so that the slip ratio of the wheel falls within the appropriate range. The vehicle motion control device according to claim 1, wherein the vehicle motion control device is configured to maintain the vehicle motion. The yawing moment generating section,
A lateral acceleration sensor that detects an acceleration of the vehicle center of gravity in a vehicle lateral direction;
A yaw rate sensor for detecting a yaw rate of the vehicle body,
The vehicle body slip angle change speed at the center point of the vehicle weight, which is a value obtained by subtracting the detected yaw rate detected by the yaw rate sensor from the value obtained by dividing the detected lateral acceleration detected by the lateral acceleration sensor by the detected vehicle speed detected by the vehicle speed sensor. The vehicle motion control device according to any one of claims 1 to 3, further comprising: yawing moment control means for controlling a yawing moment of the vehicle based on the following.

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