U.S. patent application number 09/818826 was filed with the patent office on 2001-10-04 for method for terminating a braking intervention of an adaptive cruise control system of a motor vehicle.
Invention is credited to Hellmann, Manfred, Irion, Albrecht, Winner, Hermann.
Application Number | 20010027372 09/818826 |
Document ID | / |
Family ID | 7636638 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010027372 |
Kind Code |
A1 |
Hellmann, Manfred ; et
al. |
October 4, 2001 |
Method for terminating a braking intervention of an adaptive cruise
control system of a motor vehicle
Abstract
A method for terminating a braking intervention of an adaptive
cruise control system of a motor vehicle. The braking intervention
is terminated in accordance with a predefined algorithm in response
to the driver overriding of the adaptive cruise control system. In
this context, the algorithm is formed in such a manner that a
jerk-free transition from braking to acceleration of the motor
vehicle is ensured, thus increasing the ride comfort. The
transition from braking to acceleration preferably takes place in
accordance with a linear function. Provision can also be made for
stepwise functions. To prevent the braking operation from being
terminated prematurely by an inadvertent actuation of the
accelerator, provision is made for a threshold value to be adjusted
for the accelerator for a desire of the driver to accelerate. This
threshold value is dependent on the deceleration during braking.
The higher the braking deceleration is, the more heavily the driver
must operate the accelerator to initiate the acceleration process.
In the case of a low deceleration, the threshold value is lower, so
that it suffices to step more lightly on the accelerator to bring
about an acceleration of the motor vehicle.
Inventors: |
Hellmann, Manfred;
(Hardthof, DE) ; Winner, Hermann; (Karlsruhe,
DE) ; Irion, Albrecht; (Stuttgart, DE) |
Correspondence
Address: |
KENYON & KENYON
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
7636638 |
Appl. No.: |
09/818826 |
Filed: |
March 27, 2001 |
Current U.S.
Class: |
701/96 ;
180/170 |
Current CPC
Class: |
B60T 7/22 20130101; B60T
11/103 20130101; B60W 2050/0045 20130101; B60W 2720/106 20130101;
B60T 2230/04 20130101; B60K 31/0008 20130101; B60W 30/16
20130101 |
Class at
Publication: |
701/96 ;
180/170 |
International
Class: |
B60K 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2000 |
DE |
1 00 15 303.8 |
Claims
What is claimed is:
1. A method for terminating a braking intervention of an adaptive
cruise control system of a motor vehicle, comprising the steps of:
supplying an acceleration signal to the adaptive cruise control
system in response to a driver of the motor vehicle actuating an
accelerator of the motor vehicle; in response to the acceleration
signal, causing the adaptive cruise control system to cancel a
current braking intervention and the motor vehicle to be
accelerated in accordance with a position of the accelerator; and
terminating at least one of (a) the braking intervention and (b) a
deceleration of the motor vehicle in accordance with a predefined
algorithm in response to the driver overriding the adaptive cruise
control system, the predefined algorithm ensuring a jerk-free
transition from braking to acceleration of the motor vehicle.
2. The method according to claim 1, further comprising the step of
calculating a setpoint acceleration to form the algorithm, the
setpoint acceleration being dependent on a threshold value of the
accelerator.
3. The method according to claim 2, further comprising the step of
generating the threshold value for the accelerator as a function of
the deceleration of the motor vehicle, according to a predefined
curve.
4. The method according to claim 2, wherein, in order to exceed the
threshold value, the driver needs to step on the accelerator more
heavily during higher braking deceleration and less heavily during
lower braking deceleration.
5. The method according to claim 1, further comprising the step of
empirically ascertaining the algorithm.
6. The method according to claim 1, further comprising the step of
storing values for the algorithm at least one of (a) in a table and
(b) as a function.
7. The method according to claim 1, further comprising the step of
controlling a braking pressure such that the braking intervention
is terminated at a braking pressure of about 0, the braking
pressure being controlled using an electronic stability program of
a control unit.
8. The method according to claim 1, further comprising the step of
transmitting setpoint values for engine and brake control via a
vehicle bus.
9. The method according to claim 8, wherein the vehicle bus is a
CAN bus.
10. The method according to claim 1, wherein the algorithm is
carried out using a software program.
11. The method according to claim 10, wherein the software program
is used in a control unit of the motor vehicle.
Description
BACKGROUND INFORMATION
[0001] The present invention is based on a method for terminating a
braking intervention of an adaptive cruise control system of a
motor vehicle. Adaptive cruise control systems are already known
which are used for controlling the traveling speed of a motor
vehicle as a function of the distance of a vehicle traveling ahead.
In the periodical "MOT" No. 18 of Aug. 21, 1999, section "Profi
Spezial" (professional's special), for example, a proximity warning
device using radar is reported about where a 3- or 5-beam laser or
radar sensor scans the space ahead of one's own vehicle with a
visual range of up to 150 m. The distance is calculated several
times per second from the signals reflected from the vehicle
traveling ahead and changes in one's own speed are possibly
initiated. Thus, the proximity warning device can increase or
reduce the traveling speed so as to reach or maintain a previously
input setpoint speed. In practice, however, it has turned out that
transitions between the braking of the motor vehicle and the
acceleration take place in a more or less jerky manner, in
particular when the driver wishes to increase his driving speed.
The jerky transition from braking to accelerating is felt to be
unpleasant and therefore impairs the ride comfort.
SUMMARY OF THE INVENTION
[0002] The method according to the present invention for
terminating a braking intervention of adaptive cruise control
system for a motor vehicle has the advantage over the background
art that the transition from braking to accelerating the motor
vehicle is carried out in a jerk-free manner. Because of this, the
ride comfort is advantageously increased and the changing over of
the adaptive cruise control system is not felt to be disturbing
since this behavior rather corresponds to a natural sequence.
[0003] It is particularly advantageous for an algorithm to be
formed for controlling the transition to acceleration, the
calculation of a setpoint acceleration being taken as a basis for
the algorithm. By introducing a threshold value for the accelerator
position, the braking operation of the system is advantageously
prevented from being terminated due to inadvertent contact with the
accelerator.
[0004] It is also advantageous for the threshold value to be fixed
as a function of the deceleration of the vehicle since, for
example, an unwanted interruption would have a greater effect
during strong deceleration than during low deceleration.
[0005] It is likewise considered to be beneficial that the
algorithm is determined empirically, thus resulting in a simple
adaptation to the vehicle type, the engine power, and to differing
driving styles as can be oriented toward, for example, sportive or
economic aspects.
[0006] The values for the algorithm are advantageously stored in
the form of a table or as a function and, consequently, are
available at all times.
[0007] A favorable solution is also the termination of the
proximity control of the adaptive cruise control system if the
adaptive cruise control system is overridden through the
acceleration by the driver. In this case, an adaptive cruise
control is no longer necessary because then, the driver takes over
master control during the acceleration phase.
[0008] It is also considered to be beneficial that the setpoint
values for the engine and brake control are transmitted via an
existing vehicle bus, preferably the CAN bus (Controller Area
Network). This data is then also available to further control units
and can be used, for example, for the driving dynamics control, a
navigation system, etc. Thus, it is possible, for example, for road
conditions to be considered in the control.
[0009] A particularly simple and flexible realization of the
algorithm is given by a software program which is preferably
implemented in an already existing control unit for vehicle or
engine controls.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a block diagram according to the present
invention.
[0011] FIG. 2a shows a first graph according to the present
invention.
[0012] FIG. 2b shows a second graph according to the present
invention.
[0013] FIG. 2c shows a third graph according to the present
invention.
[0014] FIG. 3 shows a flow chart according to the present
invention.
DETAILED DESCRIPTION
[0015] FIG. 1 shows a block diagram of an adaptive cruise
controller which measures, for example, the distance from a vehicle
traveling ahead with the assistance of a radar sensor. The adaptive
cruise controller has a control unit 1 to which a plurality of
sensors, for example, a speed sensor 2, a distance radar 3 and/or a
transducer 4 for detecting the position of the accelerator are
connected. Control unit 1 has a microcomputer which features a
memory 7 in which a corresponding program for determining the
vehicle's distance from a vehicle traveling ahead or from an
obstacle as a function of the driving parameters is stored. Also
stored in memory 7 are values for an algorithm for determining the
acceleration during the overriding of the adaptive cruise control.
In the case that, depending on the speed, the calculated distance
is too low, control unit 1 acts upon a braking module 5 and causes
the vehicular speed to be reduced correspondingly. Moreover,
control unit 1 can act upon an acceleration module 6 and, together
with it, control the required or desired engine torque, for
example, during the transition from braking to accelerating the
vehicle.
[0016] To explain the present invention in greater detail, first,
the technical interrelationship is illustrated in FIGS. 2a through
2c on the basis of the diagrams. To this end, FIG. 2a shows a
diagram in which, for generating a threshold value P for the
accelerator, threshold value P is plotted over setpoint
acceleration bSetpoint. The threshold value for acceleration
bSetpoint is plotted on the X-axis while normalized threshold value
P between values 0 and 1 is plotted on the Y-axis. As can further
be gathered from FIG. 2a, the relation between setpoint
acceleration bSetpoint and threshold value P is realized using a
straight line, the straight line having a negative gradient. During
practical travel operation, this means that threshold value P is
higher during higher braking deceleration than during lower braking
deceleration. In practice, during stronger braking deceleration,
the driver must therefore step on the accelerator, his/her gas
pedal stronger to exceed, for example, threshold value P1. In the
case of a lower braking deceleration, threshold value P is lower as
well so that the driver does not need to step on the gas pedal so
strongly. This connection between the braking deceleration and
threshold value P for the accelerator has the advantage that an
inadvertent contact with the accelerator does not necessarily lead
immediately to the interruption of the adaptive cruise control. The
driver rather has to step on the accelerator deliberately to
override the proximity or cruise control. This advantageously
results in more safety and a more pleasant driving experience for
the driver.
[0017] In the diagram of FIG. 2b, position P for the accelerator is
represented as a function of time t, likewise in normalized form.
This curve is provided by transducer 4 (FIG. 1). If, for example,
the threshold value for the accelerator lies at position P1, then
the driver has to depress the accelerator still further for
terminating the braking operation in a comfortable manner and for
accelerating the vehicle. Below threshold value P1, the adaptive
cruise controller would continue to operate its control function
and remain unaffected by the contact with the accelerator. This
relationship can also be gathered from FIG. 2c. Up to the
intersection of the P1-line with the pedal position line, the
normal control algorithm of the adaptive cruise controller is
carried out, i.e., the vehicle continues to be braked. Only after
this threshold value is exceeded, for example, in the case of an
ESP controller, the braking pressure is reduced in accordance with
the predefined algorithm until it reaches approximately 0 at
acceleration b0. After that, the drive control begins to operate
again, and the vehicle starts to accelerate in accordance with the
predefined algorithm to the speed desired by the driver. In this
case, however, the driver can also continue to override and take
over master control.
[0018] In the following, the mode of operation is explained once
more in greater detail on the basis of the flow chart of FIG. 3. It
is started from the assumption that the adaptive cruise control
system is currently in an operating state in which control unit 1
actively controls braking module 5 (position 31). Because of the
beginning vehicle deceleration, the switch-off threshold for the
accelerator is now determined in position 32 in accordance with
FIG. 2a. As already explained, the accelerator switch-off threshold
is reduced as the setpoint acceleration increases, starting at the
pedal maximum value down to a pedal minimum value as a function of
the setpoint acceleration. This takes place, for example according
to FIG. 2a, in a linear manner. However, provision can also be made
for nonlinear functions as well as for a stepwise change in the
acceleration or for empirically ascertained values. Thus, as the
deceleration increases, a higher pedal switching threshold ensues
for terminating the braking operation of the system. Consequently,
the pedal travel increases as the deceleration increases, and the
driver needs to actuate the accelerator deliberately to achieve a
termination of the braking operation.
[0019] In position 33, it is then checked whether the accelerator
position is larger than the instantaneous switch-off threshold for
the accelerator. If this is the case, control unit 1 increases the
setpoint value for acceleration bSetpoint in position 34 until the
system is unpressurized (FIG. 2c, b0). Subsequently, the normal
acceleration control takes place (position 35).
[0020] However, if the brake is not actively controlled according
to position 31, then the system branches directly to position 35
and continues its normal control. The same applies if the
switch-off threshold for the accelerator is not reached according
to position 33. In this case too, the normal control is continued.
This cycle is repeated continuously so that it is continued again
in position 31.
* * * * *