Patent EP0825080A2 successfully refreshed from Google Patents.
EP0825080A2
Expired / Lapsed
EP
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Anti-lock braking system
Assignee: Toyota Central R&D Labs Inc
•
Filing: 1997-08-14
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Granted: —
•
Expires: 2017-08-14
Abstract
Abstract An anti-lock braking system includes a friction torque gradient estimating unit for estimating, from a small number of parameters, the gradient of friction torque with respect to a slip speed, and controls a braking force acting on wheels on the basis of the friction torque gradient estimated by the friction torque gradient estimating unit. The friction torque gradient estimating unit may employ several types of estimating methods; e.g., a method of estimating the gradient of friction torque from only time-series data concerning a wheel speed; a method of estimating the friction torque gradient from time-series data concerning wheel deceleration as well as from braking torque or time-series data concerning physical quantities associated with the braking torque; or a method of estimating the friction torque gradient from micro-gains which are obtained when brake pressure is excited in a very small amount at the resonance frequency of a vibration system comprising a vehicle, wheels, and a road surface and which represent the characteristics of the vibration system. Further, there is also disclosed a method of determining, from the thus-estimated friction torque gradient, the limit of the characteristics of friction torque developed between the wheels and the road surface.
Inventors
- 👤 Eiichi c/o Toyota Chuo Kenkyusho Ono
- 👤 Katsuhiro C/O Toyota Chuo Kenkyusho Asano
- 👤 Takaji C/O Toyota Chuo Kenkyusho Umeno
- 👤 Hiroyuki c/o Toyota Chuo Kenkyusho Yamaguchi
- 👤 Masaru c/o Toyota Chuo Kenkyusho Sugai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 19:57
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/17; B60T8/172; B60T8/176; B60T8/1763; B60T8/17636; B60T8/32; B60T8/34; B60T8/44; B60T8/445; B60T8/48; B60T8/4809; B60T8/4827; B60T8/4845; B60T2210/00; B60T2210/10; B60T2210/12
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
83 words
An anti-lock brake controller comprising: wheel-speed sensing means which senses a wheel speed at
given sampling intervals; torque-gradient estimating means which estimates a
gradient of friction torque with respect to a slip speed in
accordance with time-series data concerning the wheel speed
detected by said wheel-speed sensing means; and control means which controls braking forces acting on
wheels in such a way that the gradient of friction torque
estimated by said torque-gradient estimating means falls
within a predetermined range including a reference value.
Claim 2
Dependent Claim
150 words
An anti-lock brake controller according to Claim 1,
wherein said torque-gradient estimating means comprises: first computation means which calculates a physical
quantity related to a variation in the wheel speed and a
physical quantity related to a change of the variation in the
wheel speed in accordance with the time-series data
concerning the wheel speed; and second computation means which calculates a physical
quantity representing both a time history of the physical
quantity related to the variation in the wheel speed and a
time history of the physical quantity related to the change
of the variation in the wheel speed, in accordance with the
physical quantity related to the variation in the wheel speed
and the physical quantity related to the change of the
variation in the wheel speed calculated by said first
computation means, and which estimates the gradient of
friction torque in accordance with the thus-calculated
physical quantity.
Claim 3
Dependent Claim
155 words
An anti-lock brake controller according to Claim 2,
wherein said second computation means approximates a state of
motion of the wheel obtained when the friction torque and the
braking forces are exerted on the wheel, using a gradient
model in which the friction torque changes linearly in
accordance with the gradient of friction torque with respect
to the slip speed; previously converts the thus-approximated state of
motion into a relationship between the gradient of friction
torque with respect to the slip speed, which is a parameter
to be identified, the physical quantity which is related to
the variation in the wheel speed and the physical quantity
which is related to the change of the variation in the wheel
speed; and estimates the gradient of friction torque with respect
to the slip speed by applying an on-line system
identification method to data obtained by sequentially
applying to the relationship the time-series data concerning
the wheel speed.
Claim 4
Dependent Claim
330 words
An anti-lock brake controller according to Claim 3,
wherein said first computation means calculates the physical
quantity related to the variation in the wheel speed
according to the Equation: i [k] = τ{ω i [k - 1] - ω i [k - 2])/J 1 where ω i [k] represents time-series data concerning the speed
of an i-th wheel detected at a sampling point in time k (k =
1, 2, ....), τ represents a sampling interval, and J is an
inertia of the wheel; and calculates the physical quantity related to the change
of the variation in the wheel speed according to the
Equation: y i [k] = - ω i [k] + 2ω i [k - 1] - ω i [k - 2], and said second computation means estimates the physical quantity
i representing the time history of the physical quantity
related to the variation in the wheel speed and the time
history of the physical quantity related to the change of the
variation in the wheel speed in accordance with the
recurrence formula: i [k] = i [k - 1] + L i [k](y i [k] - i [k] T · i [k - 1]) L i [k] = P i [ k - 1] i [ k ] λ + i [ k ] T P i [ k - 1] i [ k ] P i [k] = 1 λ P i [ k - 1] - P i [ k - 1] i [ k ] i [ k ] T P i [ k - 1] λ + i [ k ] T P i [ k - 1] i [ k ] where λ is a forgetting factor, and " T " is a transposition of
a matrix; and obtains a first element of the matrix of an estimated
value ∧ i as the gradient of friction torque with respect to
the slip speed.
Claim 5
Dependent Claim
282 words
An anti-lock brake controller comprising: wheel-deceleration sensing means for sensing a wheel
deceleration; braking torque sensing means for sensing a braking
torque; torque-gradient estimating means which estimates a
gradient of friction torque with respect to a slip speed in
accordance with time-series data concerning the wheel
deceleration detected at given sampling intervals, and time-series
data concerning the braking torque detected at given
sampling intervals or a physical quantity related to the
braking torque; and control means which controls braking forces acting on
the wheels in such a way that the gradient of friction torque
estimated by said torque-gradient estimating means falls
within a predetermined range including a reference value, wherein said torque-gradient estimating means
approximates a state of motion of the wheel obtained when the
friction torque and the braking torque are exerted on the
wheel, using a gradient model in which the friction torque
changes linearly in accordance with the gradient of friction
torque with respect to the slip speed, previously converts the thus-approximated state of
motion into a relationship between the gradient of friction
torque with respect to the slip speed, which is a parameter
to be identified, a physical quantity which is related to a
variation in the friction torque and a physical quantity
which is related to a variation in the slip speed, which are
both represented by the braking torque and the wheel
deceleration; and estimates the gradient of friction torque with respect
to the slip speed by applying an on-line system
identification method to data obtained by sequentially
applying to the relationship the time-series data concerning
detected wheel deceleration and the time-series data
concerning the braking torque or the physical quantity
related to the braking torque.
Claim 6
Dependent Claim
322 words
An anti-lock brake controller according to Claim 5,
wherein said toque-gradient estimating means estimates the
gradient of friction torque of each wheel in a manner such
that provided that "y i [j]" represents time-series data
concerning the wheel deceleration of an i-th wheel at a
sampling point in time "j," "T bi [j]" represents time-series
data concerning braking torque, "τ" represents the given
sampling interval, "J" represents an inertia of the wheel,
"R c " represents a radius of the wheel, "M" represents a mass
of the vehicle, "T b [j]" represents a vector which includes as
components the time-series data concerning the braking torque
of each wheel, "y[j]" represents a vector which includes as
components the time-series data concerning the deceleration
of each wheel, "I" represents a unit matrix, and "A"
represents a matrix which includes {(J/MR c 2 ) + 1} as diagonal
elements and J/MR c 2 as nondiagonal elements, the physical
quantity "f" concerning the variation in the friction torque
and the physical quantity concerning the variation in the
slip speed are expressed by the Formulae: f = - J(y[j + 1] - y[j]) + T b [j + 1] - T b [j] = τ · A · y[j] + τ J (I - A)T b [j]; provided that "K" is a matrix which includes as
components the gradient of friction torque of each wheel
which is a parameter to be identified, the approximated state
of motion is previously converted into the Equation: K · = f; data are obtained by sequentially applying to the
previous Equation the time-series data y i [j] (j = 1, 2,
3, ...) concerning the wheel deceleration and the time-series
data T bi [j] (j = 1, 2, 3, ...) concerning the braking torque;
and an on-line system identification method is then applied
to the thus-obtained data, whereby the gradient of friction
torque of each wheel is estimated.
Claim 7
Dependent Claim
278 words
An anti-lock brake controller according to Claim 1,
wherein said control means uses: a state of motion of each wheel obtained when the
friction torque and an amount of application of a braking
force which acts on the wheel in the vicinity of an
equilibrium point are exerted on each wheel; a state of motion of the vehicle obtained when the
friction torque developed in each wheel is exerted on the
overall vehicle; a first model in which a nonlinear variation in the
friction torque of each wheel with respect to disturbance in
the slip speed of each wheel in the vicinity of the
equilibrium point is represented as a linear variation which
changes within a first range with respect to disturbance in
the slip speed of each wheel; and a second model in which a nonlinear variation in the
gradient of the friction torque of each wheel with respect to
disturbance in the slip speed of each wheel in the vicinity
of the equilibrium point is represented as a linear variation
which changes within a second range with respect to the
disturbance in the slip speed of each wheel, thereby calculating an amount of application of the
braking force to each wheel such that the first and second
ranges fall within a predetermined allowable range and that
the gradient of friction torque determined by the second
model which is designed in such a way that the second range
falls within the predetermined allowable range matches the
gradient of friction torque estimated by the torque-gradient
estimating means; and controlling the braking force acting on each wheel in
accordance with the thus-obtained amount of application of
the braking force.
Claim 8
Dependent Claim
124 words
An anti-lock brake apparatus having a torque-gradient
estimating means comprising: micro-exciting means for exciting brake pressure in a
very small amount at a resonance frequency of a vibration
system made up of a vehicle body, wheels, and road surface; micro-gain computation means for calculating a micro-gain
which is a ratio between a very small amplitude of brake
pressure obtained when the brake pressure is excited in a
very small amount by said micro-exciting means and a very
small amplitude of the resonance frequency component of wheel
speed; and output means which estimates a gradient of friction
torque with respect to a slip speed in accordance with the
micro gain calculated by said micro-gain computation means
and which outputs the thus-estimated gradient of friction
torque.
Claim 9
Dependent Claim
149 words
An anti-lock brake controller comprising: micro-exciting means which excites braking forces
acting on either the front two wheels or the rear two wheels,
serving as reference wheels, in a very small amount at a
predetermined frequency; vibration-characteristics sensing means which senses
vibration characteristics of wheel speed of each of the two
reference wheels; braking-force control means for controlling the braking
forces acting on the two reference wheels in accordance with
variations in the vibration characteristics of each of the
two reference wheels in such a way that a friction
coefficient between the two reference wheels and the road
surface substantially reaches a peak value; and wheel speed control means for controlling the wheel
speeds of the left-side wheel and the right-side wheel of the
remaining two reference wheels so as to match the respective
wheel speeds of the left-side wheel and the right-side wheel
of the two reference wheels.
Claim 10
Dependent Claim
228 words
An anti-lock brake controller comprising: determination means for determining whether or not a
difference in friction coefficient µ between a left-side road
surface portion and a right-side road surface portion is in
excess of a reference value; micro-exciting means which excites in a very small
amount at a predetermined frequency only braking force acting
on the wheels in contact with the road surface portion having
a low friction coefficient µ when the difference has been
determined to be in excess of the reference value, and
excites in a very small amount at a predetermined frequency
braking forces acting on the wheels on both sides when the
difference has been determined not to be in excess of the
reference value; vibration-characteristics sensing means for sensing
vibration characteristics of speeds of the wheels whose
braking forces are excited in a very small amount; braking-force control means for controlling the braking
forces acting on the excited wheels so that the friction
coefficient between the excited wheels and the road surface
substantially reaches a peak value in accordance with
variations in the vibration characteristics of the excited
wheels; and friction-force control means for controlling a friction
force acting on the wheels on the high-µ road surface so as
to match a friction force acting on the wheels on the low-µ
road surface when the difference is in excess of the
reference value.
Claim 11
Dependent Claim
158 words
An anti-lock brake controller according to Claim 9,
wherein said micro-exciting means treats the front two
wheels or the rear two wheels as reference two wheels, said
micro-exciting means exciting in a very small amount at a
predetermined frequency only the braking force acting on the
wheels in contact with the road surface portion having a low
friction coefficient µ when the difference has been
determined to be in excess of the reference value, and
exciting in a very small amount at a predetermined frequency
the braking forces acting on both reference wheels when the
difference has been determined not to be in excess of the
reference value; and wheel speed control means is further provided in order
to control the wheel speeds of the left-side wheel and the
right-side wheel of the remaining two reference wheels so as
to match the respective wheel speeds of the left-side wheel
and the right-side wheel of the two reference wheels.
Claim 12
Dependent Claim
88 words
A control start determination method comprising: a wheel speed sensing step for sensing the speed of a
wheel at predetermined sampling intervals; a torque-gradient estimating step for estimating a
friction torque gradient with respect to a slip speed based
on time-series data regarding the wheel speed sensed in the
wheel speed sensing step; and a determination step for determining a starting point
for the control to bring the wheel into a predetermined state
of motion in accordance with the friction torque gradient
estimated in the torque-gradient estimating step.
Claim 13
Dependent Claim
148 words
A control start determination method according to
Claim 12, wherein said torque-gradient estimating step
comprises: first computation step which calculates a physical
quantity related to a variation in the wheel speed and a
physical quantity related to a change of the variation in the
wheel speed in accordance with the time-series data
concerning the wheel speed; and second computation step which calculates a physical
quantity representing both a time history of the physical
quantity related to the wheel speed and a time history of the
physical quantity related to the change of the variation in
the wheel speed, in accordance with the physical quantity
related to the variation in the wheel speed and the physical
quantity related to the change of the variation in the wheel
speed calculated by said first computation means, and which
estimates the gradient of friction torque in accordance with
the thus-calculated physical quantity.
Claim 14
Dependent Claim
331 words
A control start determination method according to
Claim 13, wherein said first computation step calculates the
physical quantity related to the variation in the wheel speed
according to the Equation: i [k] = τ{ω i [k - 1] - ω i [k - 2]}/J 1 where ω i [k] represents time-series data concerning the speed
of an i-th wheel detected at a sampling point in time k (k =
1, 2, ....), τ represents a sampling interval, and J is an
inertia of the wheel; and calculates the physical quantity related to the change
of the variation in the wheel speed according to the
Equation: y i [k] = - ω i [k] + 2ω i [k - 1] - ω i [k - 2], and said second computation step estimates the physical
quantity i representing the time history of the physical
quantity related to the variation in the wheel speed and the
time history of the physical quantity related to the change
of the variation in the wheel speed in accordance with the
recurrence formula: i [k] = i [k - 1] + L i [k](y i [k] - i [k] T · i [k - 1]) L i [k] = P i [ k - 1] i [ k ] λ + i [ k ] T P i [ k - 1] i [ k ] P i [k] = 1 λ P i [ k - 1] - P i [ k - 1] i [ k ] i [ k ] T P i [ k - 1] λ + i [ k ] T P i [ k - 1] i [ k ] where λ is a forgetting factor, and " T " is a transposition of
a matrix; and obtains a first element of the matrix of an estimated
value ∧ i as the gradient of friction torque with respect to
the slip speed.
Claim 15
Dependent Claim
183 words
A wheel-behavior-quantity servo controller
comprising: wheel-behavior-quantity detecting means for detecting a
quantity of behavior of a wheel which is a physical quantity
associated with a motion of the wheel; limit determination means which calculates, as a
quantity of limit determination, a friction torque gradient
indicating a gradient of friction torque with respect to a
slip speed or a physical quantity associated with the
friction torque gradient via the wheel motion, and which
determines the limit of the characteristics of the friction
torque between the wheel and the road surface in accordance
with the quantity of limit determination; target-behavior-quantity calculation means which
calculates a target value of the quantity of wheel behavior
used for controlling the quantity of limit determination to
within the limit of friction torque characteristics in
accordance with the result of limit determination of said
limit determination means; and servo control means which controls the motion of the
wheel so as to cause the quantity of wheel behavior detected
by said wheel-behavior-quantity detecting means to follow the
target value of the quantity of wheel behavior calculated by
the target-behavior-quantity calculation means.
Claim 16
Dependent Claim
142 words
A wheel-behavior-quantity servo controller
according to Claim 15, further comprising braking torque
sensing means for sensing a braking torque, wherein said wheel-behavior-quantity detecting means calculates
a wheel deceleration as the quantity of behavior of a wheel;
and in accordance with the detected braking torque and the
detected wheel deceleration, said limit determination means
calculates, as a quantity of limit determination, either
wheel deceleration or braking torque which will be obtained
on the assumption that the slip speed is constant in the
state of equilibrium of motion of the wheel, and in
accordance with the comparison between the quantity of limit
determination and the actually detected wheel deceleration,
or the comparison between the quantity of limit determination
and the actually detected braking torque, said limit
determination means determines the limit of the
characteristics of friction torque between the wheel and the
road surface.
Claim 17
Dependent Claim
54 words
A wheel-behavior-quantity servo controller
according to Claim 15, wherein said limit determination means calculates, as a
quantity of limit determination, a braking torque gradient
based on time-series data of braking torque and time-series
data of wheel deceleration and determines the limit of the
characteristics of friction torque based on the quantity of
limit determination.
Claim 18
Dependent Claim
48 words
A wheel-behavior-quantity servo controller
according to Claim 15, wherein said limit determination means calculates, as a
quantity of limit determination, a friction torque gradient
based on time-series data of wheel speed and determines the
limit of the characteristics of friction torque based on the
quantity of limit determination.
Claim 19
Dependent Claim
57 words
A wheel-behavior-quantity servo controller
according to Claim 15, further comprising micro-exciting
means for exciting a brake pressure in a very small amount at
a resonance frequency of a vibration system made up of a
vehicle body, wheels, and road surface, wherein said limit determination means calculates, as a
quantity of limit determination, a micro-gain which is a
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