U.S. patent application number 11/709316 was filed with the patent office on 2007-09-20 for vehicle motion control system.
This patent application is currently assigned to Honda Motor Co., Ltd.. Invention is credited to Hiromi Inagaki, Yuki Ito, Naoto Ohkubo, Osamu Yamamoto.
Application Number | 20070219690 11/709316 |
Document ID | / |
Family ID | 38375155 |
Filed Date | 2007-09-20 |
United States Patent
Application |
20070219690 |
Kind Code |
A1 |
Ohkubo; Naoto ; et
al. |
September 20, 2007 |
VEHICLE MOTION CONTROL SYSTEM
Abstract
A vehicle motion control system is provided. In a first state
requiring understeer suppressing control, a controller determines,
based on a yaw rate deviation, a first control amount of an
actuator selected so as to generate an inward turning moment a
vehicle. In a second state requiring spin suppressing control, the
controller determines, based on the sideways slip angular velocity,
a second control amount of an actuator selected so as to generate
an outward turning moment in the vehicle. When the first and second
states are concurrent, the controller selects an actuator to be
controlled by the larger of the absolute values of first and second
cooperative control amounts, and determines a control amount of the
selected actuator as the sum of the first and second cooperative
control amounts. Accordingly, the understeer suppressing control
and the spin suppressing control can be performed in parallel,
improving control performance.
Inventors: |
Ohkubo; Naoto; (Saitama,
JP) ; Yamamoto; Osamu; (Saitama, JP) ; Ito;
Yuki; (Saitama, JP) ; Inagaki; Hiromi;
(Saitama, JP) |
Correspondence
Address: |
CARRIER BLACKMAN AND ASSOCIATES
24101 NOVI ROAD, SUITE 100
NOVI
MI
48375
US
|
Assignee: |
Honda Motor Co., Ltd.
Tokyo
JP
|
Family ID: |
38375155 |
Appl. No.: |
11/709316 |
Filed: |
February 21, 2007 |
Current U.S.
Class: |
701/41 |
Current CPC
Class: |
B60W 40/11 20130101;
B60T 2230/02 20130101; B60W 10/184 20130101; B60T 8/1755 20130101;
B60W 40/114 20130101; B60W 40/103 20130101; B60W 40/112
20130101 |
Class at
Publication: |
701/41 |
International
Class: |
B62D 6/00 20060101
B62D006/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2006 |
JP |
2006-74602 |
Claims
1. A vehicle motion control system comprising: plural actuators,
each actuator configured to generate a turning moment in the
vehicle; a steering angle detecting device which detects a steering
angle input by a driver; a vehicle speed detecting device which
detects a vehicle speed; a yaw rate detecting device which detects
a yaw rate of a vehicle; a sideways slip angular velocity detecting
device which detects a sideways slip angular velocity of the
vehicle; a reference yaw rate calculating device which calculates a
reference yaw rate intended by the driver based on the steering
angle detected by the steering angle detecting device and the
vehicle speed detected by the vehicle speed detecting device; a yaw
rate deviation calculating device which calculates a yaw rate
deviation, the yaw rate deviation comprising a deviation between
the reference yaw rate calculated by the reference yaw rate
calculating device and the yaw rate detected by the yaw rate
detecting device; and a control amount determining device which,
based on the value detected by the sideways slip angular velocity
detecting device and the value calculated by the yaw rate deviation
calculating device, is capable of selecting an appropriate actuator
from the group of plural actuators, and which is capable of
determining a control amount of the selected actuator, wherein in a
first state in which an absolute value of the reference yaw rate is
larger by a first predetermined value or more than an absolute
value of the detected yaw rate, the control amount determining
device selects, based on the yaw rate deviation calculated by the
yaw rate deviation calculating device, one of the actuators which
generates an inward turning moment in the vehicle, and determines a
first control amount of the selected actuator, wherein in a second
state in which an absolute value of the sideways slip angular
velocity detected by the sideways slip angular velocity detecting
device exceeds a second predetermined value, the control amount
determining device selects, based on the sideways slip angular
velocity, one of the actuators which generates an outward turning
moment in the vehicle, and determines a second control amount of
the selected actuator, and wherein when the first and second states
occur at the same time, the control amount determining device
determines separately a first cooperative control amount and a
second cooperative control amount, based on the first control
amount and second control amount having increase/decrease
directions opposite to each other, selects an actuator to be
controlled by the larger of the first cooperative control amount
and the second cooperative control amount, and determines a control
amount of the selected actuator as the sum of the first cooperative
control amount and the second cooperative control amount.
2. The vehicle motion control system according to claim 1, further
comprising a lateral acceleration detecting device which detects a
lateral acceleration of the vehicle, wherein the second
predetermined value varies in accordance with the lateral
acceleration detected by the lateral acceleration detecting
device.
3. The vehicle motion control system according to claim 1, wherein
the first cooperative control amount comprises the first control
amount multiplied by a first weighting coefficient, and the second
cooperative control amount comprises the second control amount
multiplied by a second weighting coefficient.
4. The vehicle motion control system according to claim 1, wherein
the first state corresponds to an understeer suppression control
state, and the first control amount corresponds to a control amount
of an understeer suppressing control, and the second state
corresponds to a spin suppression control state, and the second
control amount corresponds to a control amount of a spin
suppressing control.
5. The vehicle motion control system according to claim 1, further
comprising a lateral acceleration detecting device which detects a
lateral acceleration of the vehicle, wherein the sideways slip
angular velocity detecting device calculates a sideways slip
angular velocity of the vehicle by subtracting the detected yaw
rate from a value obtained by dividing the detected lateral
acceleration by the detected vehicle speed.
6. The vehicle motion control system according to claim 1, wherein
each of the plural actuators comprises a wheel brake.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present invention claims priority under 35 USC 119 based
on Japanese patent application No. 2006-74602, filed on Mar. 17,
2006. The subject matter of this priority document is incorporated
by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a vehicle motion control
system, and particularly to a vehicle motion control system capable
of performing, in parallel, motion control based on yaw rate and
motion control based on sideways slip angular velocity.
[0004] 2. Description of the Related Art
[0005] Japanese Patent No. 3324965 discloses a vehicle motion
control system which performs motion control based on a yaw rate
deviation between a reference yaw rate determined based on a
steering angle and a vehicle speed, and a detected yaw rate, when
the vehicle turns in an understeer state. In addition, the vehicle
motion control system performs motion control based on a sideways
slip angular velocity when the vehicle turns in an oversteer
state.
[0006] The oversteer suppressing control, the understeer
suppressing control and the spin suppressing control of a vehicle
are performed according to yaw rate deviation and sideways slip
angular velocity in respective regions illustrated in FIG. 4. In
the figure, there is a region where motion control based on yaw
rate deviation and motion control based on sideways slip angular
velocity overlap each other. Particularly, in a region where
understeer suppressing control for suppressing understeer based on
yaw rate deviation and spin suppressing control based on sideways
slip angular velocity overlap each other, the directions of turning
moment required in these controls are opposite to each other.
Accordingly, when the understeer suppressing control for
suppressing understeer based on yaw rate deviation and the spin
suppressing control based on sideways slip angular velocity are
performed in parallel to generate a turning moment, either an
inward turning moment or an outward turning moment is generated
depending on the situation. Thus, the driver of the vehicle has
difficulty in predicting whether the motion controls will proceed
in a turn accelerating direction or a turn suppressing direction,
resulting in a deterioration in vehicle control performance.
SUMMARY OF THE INVENTION
[0007] The present invention has been achieved in view of the above
circumstances, and has as an object to provide a vehicle motion
control system which can perform, in parallel, understeer
suppressing control based on yaw rate deviation and spin
suppressing control based on sideways slip angular velocity, and
which can improve control performance.
[0008] In order to achieve the above object, according to a first
feature of the present invention, there is provided a vehicle
motion control system comprising: a steering angle detecting device
for detecting a steering angle input by a driver; a vehicle speed
detecting device for detecting a vehicle speed; a yaw rate
detecting device for detecting a yaw rate of a vehicle; a sideways
slip angular velocity detecting device for detecting a sideways
slip angular velocity of the vehicle; a reference yaw rate
calculating device for calculating a reference yaw rate intended by
the driver based on the steering angle detected by the steering
angle detecting device and the vehicle speed detected by the
vehicle speed detecting device; a yaw rate deviation calculating
device for calculating a yaw rate deviation being a deviation
between the reference yaw rate calculated by the reference yaw rate
calculating device and the yaw rate detected by the yaw rate
detecting device; and a control amount determining device which,
based on the value detected by the sideways slip angular velocity
detecting device and the value calculated by the yaw rate deviation
calculating device, selects an appropriate actuator from plural
actuators each generating a turning moment in the vehicle, and
which determines a control amount of the selected actuator. In a
first state where the absolute value of the reference yaw rate is
larger by a predetermined value or more than the absolute value of
the detected yaw rate, the control amount determining device
selects, based on the yaw rate deviation calculated by the yaw rate
deviation calculating device, one of the actuators which generates
an inward turning moment in the vehicle, and determines a first
control amount of the selected actuator. In addition, in a second
state where the absolute value of the sideways slip angular
velocity detected by the sideways slip angular velocity detecting
device exceeds a predetermined value, the control amount
determining device selects, based on the sideways slip angular
velocity, one of the actuators which generates an outward turning
moment in the vehicle, and determines a second control amount of
the selected actuator. When the first and second states occur at
the same time, the control amount determining device separately
determines a first cooperative control amount and a second
cooperative control amount based on the first control amount and
second control amount having increase/decrease directions opposite
to each other. In addition, the control amount determining device
selects an actuator to be controlled by the larger of the first
cooperative control amount and the second cooperative control
amount, and determines a control amount of the selected actuator as
the sum of the first cooperative control amount and the second
cooperative control amount.
[0009] With the first feature, when the first state, in which the
absolute value of the reference yaw rate is larger by a
predetermined value or more than the absolute value of the yaw rate
detected by the yaw rate detecting device, i.e., the state where
the understeer suppressing control is required, occurs concurrently
with the second state, in which the absolute value of the sideways
slip angular velocity exceeds a predetermined value, i.e., the
state where the spin suppressing control is required, then the
absolute value of the first cooperative control amount dependent on
the first control amount for generating an inward turning moment
based on the yaw rate deviation is compared with the absolute value
of the second cooperative control amount dependent on the second
control amount for generating an outward turning moment based on
the sideways slip angular velocity. Based on the comparison, the
actuator to be controlled by the larger of the first cooperative
control amount and the second cooperative control amount is
selected, and the control amount of the selected actuator is
determined as the sum of the first and second cooperative control
amounts. Accordingly, in a state where both the understeer
suppressing control and the spin suppressing control are required,
the inward turning moment control and the outward turning moment
control are prevented from interfering with each other, and thus
the understeer suppressing control based on the driver's will is
effected even during spin suppressing control, thereby improving
control performance.
[0010] According to a second feature of the present invention, in
addition to the first feature, the device further comprises a
lateral acceleration detecting device for detecting a lateral
acceleration of the vehicle. The predetermined value is set so as
to vary in accordance with the lateral acceleration detected by the
lateral acceleration detecting device.
[0011] The above-mentioned object, other objects, characteristics,
and advantages of the present invention will become apparent from a
preferred embodiment, which will be described in detail below by
reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a block diagram illustrating a configuration of a
motion control system according to an embodiment of the present
invention.
[0013] FIG. 2 is a flowchart illustrating a control amount
determination procedure used by the control amount determining
device.
[0014] FIG. 3 is a graph of lateral acceleration versus side slip
angular velocity, illustrating a predetermined value of sideways
slip angular velocity for determining whether to perform control of
generating an outward turning moment.
[0015] FIG. 4 is a graph of yaw rate deviation versus side slip
angular velocity illustrating regions where oversteer suppressing
control, understeer suppressing control and spin suppressing
control are to be performed, respectively.
DETAILED DESCRIPTION
[0016] First, referring to FIG. 1, a four-wheeled vehicle includes
wheel brakes as actuators in the front/rear/left/right sides as
follows: a front left wheel brake 5FL; a front right wheel brake
5FR; a rear left wheel brake 5RL and a rear right wheel brake 5RR.
When motion control is performed during turning of a vehicle, the
one of the wheel brakes 5FL to 5RR which is required for the motion
control is selected, and the selected wheel brake performs a
braking operation, thereby performing the motion control of the
vehicle during turning.
[0017] When motion control of the vehicle is performed during
turning, a steering angle input by the driver is detected by
steering angle detecting device 6, a yaw rate of the vehicle is
detected by a yaw rate detecting device 7, a lateral acceleration
of the vehicle is detected by a lateral acceleration detecting
device 8, and a vehicle speed is detected by a vehicle speed
detecting device 9, for example, based on a speed of follower
wheels.
[0018] The steering angle detected by the steering angle detecting
device 6 and the vehicle speed detected by the vehicle speed
detecting device 9 are input to a reference yaw rate calculating
device 10. The reference yaw rate calculating device 10 calculates,
based on the steering angle and the vehicle speed, a reference yaw
rate intended by the driver. Further, the reference yaw rate
calculated by the reference yaw rate calculating device 10 and the
yaw rate detected by the yaw rate detecting device 7 are input to a
yaw rate deviation calculating device 11. The yaw rate deviation
calculating device 11 calculates a yaw rate deviation that is a
deviation between the reference yaw rate and the detected yaw
rate.
[0019] The yaw rate deviation calculating device 11 performs a
procedure of assigning a positive sign to the reference yaw rate
and detected yaw rate on a right turn side, and assigning a
negative sign to the reference yaw rate and detected yaw rate on a
left turn side, for example; and then subtracting the detected yaw
rate from the reference yaw rate.
[0020] The yaw rate detected by the yaw rate detecting device 7,
the lateral acceleration detected by the lateral acceleration
detecting device 8, and the vehicle speed detected by the vehicle
speed detecting device 9 are input to sideways slip angular
velocity detecting device 12; and the sideways slip angular
velocity detecting device 12 calculates a sideways slip angular
velocity of the vehicle, for example, by subtracting the detected
yaw rate from a value obtained by dividing the lateral acceleration
by the vehicle speed.
[0021] The yaw rate deviation obtained by the yaw rate deviation
calculating device 11, the lateral acceleration obtained by the
lateral acceleration detecting device 8, and the sideways slip
angular velocity obtained by the sideways slip angular velocity
detecting device 12 are input to control amount determining device
13. The control amount determining device 13 selects, based on the
yaw rate deviation, the lateral acceleration and the sideways slip
angular velocity, one of the wheel brakes 5FL to 5RR which is
required for generating a turning moment in the vehicle, and
determines a control amount of the selected wheel brake.
[0022] The determining procedure in the control amount determining
device 13 will be described with reference to FIG. 2. In FIG. 2,
oversteer suppressing control based on yaw rate deviation is
denoted as "OS suppressing control"; understeer suppressing control
based on yaw rate deviation is denoted as "US suppressing control";
and spin suppressing control is denoted as "SP suppressing
control".
[0023] In step S1, it is determined, based on the yaw rate
deviation obtained by the yaw rate deviation calculating device 11,
whether a condition for oversteer suppressing control intervention
holds. Specifically, in the yaw rate deviation calculating device
11, the detected yaw rate obtained by the yaw rate detecting device
7 is subtracted from the reference yaw rate obtained by the
reference yaw rate calculating device 10 to obtain a yaw rate
deviation, and if the absolute value of the detected yaw rate is
larger by a predetermined value or more than the absolute value of
the reference yaw rate, it is determined that a condition for
oversteer suppressing control intervention holds. That is, for
example, when the yaw rate deviation has a predetermined value or
more on the negative side during a right turn, or when the yaw rate
deviation has a predetermined value or more on the positive side
during a left turn, it is determined that a condition for oversteer
suppressing control intervention holds. If it is determined that a
condition for oversteer suppressing control intervention does not
hold, the flow proceeds to step S2.
[0024] In step S2, it is determined based on the yaw rate deviation
whether a condition for understeer suppressing control intervention
holds. Specifically, if the absolute value of the reference yaw
rate is larger by a predetermined value or more than the absolute
value of the detected yaw rate, it is determined that a condition
for understeer suppressing control intervention holds. For example,
when the yaw rate deviation has a predetermined value or more on
the positive side during a right turn, or when the yaw rate
deviation has a predetermined value or more on the negative side
during a left turn, it is determined that a condition for
understeer suppressing control intervention holds. If it is
determined that a condition for understeer suppressing control
intervention does not hold, the flow proceeds to step S3.
[0025] In step S3, it is determined whether the sideways slip
angular velocity detected by the sideways slip angular velocity
detecting device 12 exceeds a predetermined value, thereby
determining whether a condition for spin suppressing control
intervention holds. Here, as illustrated in FIG. 3, the
predetermined value varies according to the lateral acceleration
detected by the lateral acceleration detecting device 8. For
example, when the right turn direction is set as "positive side"
and the left turn direction, as "negative side", if a sideways slip
angular velocity on the right turn side resides in a negative
region (the region indicated by hatching) having a value smaller
than the predetermined value arranged in the negative region, a
condition for spin suppressing control intervention holds; and if a
sideways slip angular velocity on the left turn side resides in a
positive region (the region indicated by hatching) having a value
larger than the predetermined value arranged in the positive
region, a condition for spin suppressing control intervention
holds.
[0026] If it is determined in the above step S3 that a condition
for spin suppressing control intervention does not hold, the
control amount is set to "0" in step S4. If it is determined that a
condition for spin suppressing control intervention holds, the
control amount is set to "BDRES" in step S5, and a required yaw
moment DMBD in the spin suppressing control is calculated in the
subsequent step S6, and the one of the wheel brakes (5FL to 5RR)
which performs the spin suppressing control based on the sideways
slip angular velocity and generates an outward turning moment in
the vehicle, is selected in step S7.
[0027] If it is determined in step S1 that a condition for
oversteer suppressing control intervention holds, the flow proceeds
from step S1 to step S8. In step S8, a required yaw moment DMOS in
the oversteer suppressing control is calculated. Subsequently, in
step S9, it is determined whether a condition for spin suppressing
control intervention holds, and if it is determined that a
condition for spin suppressing control intervention does not hold,
the control amount is set to YRRES in step S10. Thereafter, in step
S11, oversteer suppressing control is selected, and one of the
wheel brakes (5FL to 5RR) which generates an outward turning moment
in the vehicle, is selected.
[0028] Alternatively, if it is determined in step S9 that a
condition for spin suppressing control intervention holds, the flow
proceeds to step S12. In step 12, a required yaw moment DMBD in the
spin suppressing control is calculated, and thereafter in step S13,
the absolute value |DMOS| of the required yaw moment DMOS in the
oversteer suppressing control is compared with the absolute value
|DMBD| of the required yaw moment DMBD in the spin suppressing
control. As a result, if |DMOS|.gtoreq.|DMBD|, the flow proceeds
from step 13 to step S11, and if |DMOS|<|DMBD|, the flow
proceeds from step 13 to step S7.
[0029] If it is determined in step S2 that a condition for
understeer suppressing control intervention holds, i.e., if there
has occurred the first state where the absolute value of the
reference yaw rate is larger by a predetermined value or more than
the absolute value of the detected yaw rate, then the flow proceeds
from step S2 to step S14. In step S14 it is determined whether a
condition for spin suppressing control intervention holds, i.e.,
whether the second state has occurred. If it is determined that a
condition for spin suppressing control intervention does not hold,
the first control amount is set to YRRES in step S15, and a
required yaw moment DMUS in the understeer suppressing control is
calculated in the subsequent step S16, and further one of the wheel
brakes (5FL to 5RR) which performs understeer suppressing control
based on the yaw rate deviation and generates an inward turning
moment in the vehicle, is selected in step S17.
[0030] Alternatively, if it is determined in step S14 that a
condition for spin suppressing control intervention holds, i.e., if
it is determined that the first state where a condition for
understeer suppressing control intervention holds and the second
state where a condition for spin suppressing control intervention
holds have occurred at the same time, then the flow proceeds to
step S18. Here, the understeer suppressing control and the spin
suppressing control generate moments in opposite directions, and
therefore the direction of the first control amount YRRES being the
control amount of the understeer suppressing control is opposite to
that of the second control amount BDRES being the control amount of
the spin suppressing control. Thus, in step S18, a first
cooperative control amount KyYRRES and a second cooperative control
amount KbBDRES are separately set, based on the first control
amount YRRES and the second control amount BDRES, respectively,
where Ky is an understeer suppressing control weighting coefficient
and Kb is a spin suppressing control weighting coefficient. Then
the sum (KyYRRES+KbBDRES) of the cooperative control amounts
KyYRRES and KbBDRES is determined as the control amount.
[0031] Further, in the subsequent S19, it is determined which is
larger between the absolute value |KyYRRES| of the first
cooperative control amount KyYRRES and the absolute value |KbBDRES|
of the second cooperative control amount. If
|KyYRRES|.gtoreq.|KbBDRES| the flow proceeds to step S16 to select
understeer suppressing control, and if |KyYRRES|<|KbBDRES| a
required yaw moment DMBD in spin suppressing control is calculated
in step S20 and thereafter the flow proceeds to step S7 to select
the spin suppressing control.
[0032] That is, in the control amount determining device 13, when
there concurrently occur the first state where the absolute value
of the reference yaw rate is larger by a predetermined value or
more than the absolute value of the detected yaw rate, and the
second state where the sideways slip angular velocity exceeds a
predetermined value, then the absolute value of the first
cooperative control amount KyYRRES based the first control amount
YRRES determined in the first state is compared with the absolute
value of the second cooperative control amount KbBDRES based on the
second control amount BDRES determined in the second state. The one
of the wheel brakes 5FL to 5RR which is to be controlled by the
larger of the two absolute values is thereby selected, and the
control amount of the selected wheel brake, as the sum
(KyYRRES+KbBDRES) of the first and second cooperative control
amounts KyYRRES and KbBDRES, is determined.
[0033] Referring again to FIG. 1, according to the selection of a
wheel brake and the determination of a control amount in the
control amount determining device 13, an understeer suppressing
control logic circuit 14, an oversteer suppressing control logic
circuit 15 and a spin suppressing control logic circuit 16
determine an operating amount of the one selected from among the
wheel brakes 5FL to 5RR, and then a brake control circuit 17
controls the operation of the one selected from among the wheel
brakes 5FL to 5RR in accordance with signals received from the
logic circuits 14, 15 and 16.
[0034] The operation of the present embodiment will now be
described. In the first state where the absolute value of the
reference yaw rate is larger by a predetermined value or more than
the absolute value of the detected yaw rate, the control amount
determining device 13 selects, based on the yaw rate deviation
calculated by the yaw rate deviation calculating device 11, one of
the wheel brakes 5FL to 5RR which generates an inward turning
moment in the vehicle, and determines the first control amount
YRRES of the selected wheel brake. In the second state where the
sideways slip angular velocity detected by the sideways slip
angular velocity detecting device 12 exceeds a predetermined value,
the control amount determining device 13 selects, based on the
sideways slip angular velocity, a wheel brake which generates an
outward turning moment in the vehicle, and determines the second
control amount BDRES of the selected wheel brake. When the first
and second states occur at the same time, the control amount
determining device 13 selects a wheel brake to be controlled by the
larger of the absolute values of the first and second cooperative
control amounts KyYRRES and KbBDRES separately determined based on
the first and second control amounts YRRES and BDRES having
increase/decrease directions opposite to each other, and determines
a control amount of the selected wheel brake as the sum
(KyYRRES+KbBDRES) of the first and second cooperative control
amounts.
[0035] According to the control amount determining device 13
described above, when the first state, i.e., the state requiring
the understeer suppressing control, and the second state, i.e., the
state requiring the spin suppressing control, occur at the same
time, that is, under conditions requiring both the understeer
suppressing control and the spin suppressing control, the inward
turning moment control and the outward turning moment control are
prevented from interfering with each other. As a result, the
understeer suppressing control intended by the vehicle driver is
reflected even during the spin suppressing control, thus improving
control performance.
[0036] The embodiment of the present invention has been described
above, but various changes in design may be made without departing
from the subject matter of the present invention.
* * * * *