# US 10,768,070 B2 · Method of determining the height of the gravity center of a vehicle

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- Number: US 10,768,070 B2
- Document ID: US10768070B2
- Status: Granted
- Kind: B2
- Application number: 15/766,971
- Filed: 2015-10-16
- Published: 2018-10-25
- Granted: 2020-09-08
- Earliest claimed: 2015-10-16
- Assignees: Volvo Truck Corporation
- Applicants: Volvo Truck Corporation
- Inventors: Jean-Baptiste Doray; Fabrice Ranc
- Web page: https://patentgrep.com/patent/US10768070B2

## CPC

- G01M 1/122: {Determining position of centre of gravity}
- G01M 17/007: Wheeled or endless-tracked vehicles (G01M17/08 takes precedence)
- B60G 2400/106: longitudinal with regard to vehicle, e.g. braking
- B60G 2400/63: Location of the center of gravity
- B60T 8/172: Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)}
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- B60G: VEHICLE SUSPENSION ARRANGEMENTS (air-cushion vehicles B60V; {cycle suspensions B62K25/00})
- B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES

## Abstract

The height of the center of gravity of a vehicle having at least 3 axles is estimated using the slippage rate of the wheels.

## Claims

### Claim 1

Method of determination of the height of the gravity center HG (HGr, Hg, HGst) of a vehicle, or an element of the vehicle, wherein 3 reference points Pa, Pb and Pc are predetermined, the method comprising the steps of:
a) determining the tangential forces TAn (TAax, TAbx, TAcx) at all the axles An (Aa, Ab, Ac) of the vehicle, during a first acceleration phase,
b) deducing from the tangential forces TAn (TAax, TAbx, TAcx) determined in step a) the corresponding normal forces NAn (NAax, NAbx, NAcx) during the first acceleration phase,
c) determining the normal force NPb at one of the predetermined reference points Pb, during a first acceleration phase, using the values determined in steps a) and b),
d) repeating steps a), b), and c) at least once during a second acceleration phase, distinct from the first acceleration phase, and
deducing from the preceding steps a), b), c) and d) the height of the gravity center HG (HGr, Hg, HGst) of the vehicle, or an element of the vehicle, by computing the normal forces NPa, NPb and NPc at the 3 predetermined reference points Pa, Pb and Pc, using an algorithm wherein in step a) the tangential forces TAn are determined according to the formula (1): TAnx=Q·VAnx+FAnx (1) wherein:
TAnx denotes the tangential force at an axle An during a braking period x,
Q denotes the brake factor,
VAnx denotes the braking pressure applied at an axle An during a braking period x, and
FAnx denotes the driving force applied at an axle An during a braking period x.

### Claim 2 (depends on 1)

Method according to claim 1, wherein the normal forces are deduced from the tangential forces in step b) according to the general formula (5):
N
Anx
=
T
Anx
η
An
·
a
An
·
τ
An
(
5
)
wherein:
NAnx denotes the normal force at an axle An during a braking period x,
TAnx denotes the tangential forces at an axle An during a braking period x,
ηAn denotes the number of wheels at the axle An,
aAn denotes a coefficient comprised between 0 and 1, and
τAn denotes the slippage rate of the wheels of an axle An.

### Claim 3 (depends on 1)

Method according to claim 1, wherein the vehicle is a rigid vehicle having 3 axles Aa, Ab and Ac, and wherein the 3 reference points Pa, Pb and Pc correspond to the 3 axles (Aa, Ab, Ac).

### Claim 4 (depends on 1)

Method according to claim 1, wherein the vehicle is an assembly of a tractor and a semi-trailer, wherein one of the reference points Pa corresponds to an axle Aa of the tractor, a second reference point Pc corresponds to an axle Ac of the semi-trailer, and wherein the third reference point Pb corresponds to the fifth wheel of the tractor.

### Claim 5 (depends on 1)

Method according to claim 1, wherein the vehicle is an assembly of a tractor having two axles and a semi-trailer, wherein one of the reference point Pb corresponds to the fifth wheel of the tractor, and wherein the normal force at reference point Pb is determined in step c) according to formula (8a):
N
Pb
′
=
N
g
⁢
Cos
⁡
(
α
)
⁡
[
(
E
⁢
⁢
1
-
E
g
)
⁢
Y
a
-
E
g
⁢
Y
b
]
+
(
Y
a
+
Y
b
)
[
H
g
⁢
(
T
Aa
+
T
Ab
+
F
Ab
+
F
A
⁢
⁢
a
)
+
(
H
Pb
′
-
H
g
)
⁢
T
Pb
′
]
[
(
E
g
-
E
⁢
⁢
1
)
·
Y
a
+
E
g
·
Y
b
]
+
(
E
Pb
′
-
E
g
)
⁡
[
Y
b
+
Y
a
]
(
8
⁢
a
)
wherein:
Ya denotes TAbTAa,
Yb denotes TAa2τAb,
Ng denotes the normal force at the center of gravity g of the tractor,
NPb′ denotes the normal force at the point of reference Pb′,
E1 denotes the distance between the first axle Aa and the second axle Ab of the tractor,
TAa denotes the tangential force at the first axle Aa,
TAb denotes the tangential force at the second axle Ab,
TPb′ denotes the tangential force at the reference point Pb′,
τAa denotes the slippage rate at the first axle Aa,
τAb denotes the slippage rate at the second axle Ab,
Eg denotes the distance between the gravity center g of the tractor and its first axle Aa,
Hg denotes the height of the gravity center g of the tractor,
EPb′ denotes the distance between the reference point Pb′ and the first axle Aa of the tractor,
HPb′ denotes the height of the reference point Pb′, and
a denotes the inclination angle of the slope.

### Claim 6 (depends on 1)

Method according to claim 1, wherein the vehicle is an assembly of a tractor having three axles and a semi-trailer, wherein one of the reference point Pb′ corresponds to the fifth wheel of the tractor, and wherein the normal force at the fifth wheel is determined in step c) according to formula (8b):
N
Pb
′
=
N
g
⁢
Cos
⁡
(
α
)
⁢
Z
1
-
H
g
⁡
(
T
Aa
+
T
Ab
+
T
Ac
-
T
Pb
′
)
⁢
Z
2
Z
3
+
(
E
g
-
E
Pb
′
)
⁢
Z
2
(
8
⁢
b
)
wherein:
Z1={EgTAaXAcXAb−2τAa(E1−Eg)TAbXAc(Eg−EPb′)2τAaTAbXAb}
Z2={2τAaTAbXAc+XAbTAaXAc+2τAaTAcXAb}
Z3={2τAa(E1−Eg)TAbXAc+(Eg−EPb′)2τAaTAcXAb−EgTAaXAcXAb}
where:
NPb′ denotes the normal force at the point of reference Pb′,
Ng denotes the normal force at the center of gravity g of the tractor,
E1 denotes the distance between the first axle Aa and the second axle Ab,
Eg denotes the distance between the gravity center g of the tractor and its first axle Aa,
Hg denotes the height of the gravity center g of the tractor,
TAa denotes the tangential force at the first axle Aa of the tractor,
TAb denotes the tangential force at the second axle Ab of the tractor,
TAc denotes the tangential force at the third axle Ac of the tractor,
TPb′ denotes the tangential force at the reference point Pb′,
τAa denotes the slippage rate at the first axle Aa of the tractor,
τAb denotes the slippage rate at the second axle Ab of the tractor,
τAc denotes the slippage rate at the third axle Ac of the tractor,
EPb′ denotes the distance between the reference point Pb′ and the first axle Aa of the tractor,
XAb denotes ηAbτAb, wherein ηAb is the number of wheels at the axle Ab, and
XAc corresponds to the terms ηAcτAb wherein ηAc is the number of wheels of the axle Ac.

### Claim 7 (depends on 1)

Method according to claim 1, wherein the algorithm used in the determination of the height of the gravity center HG in step e) comprises the following formula
HG
=
d
1
⁡
(
N
Pb
⁢
⁢
2
-
N
Pb
⁢
⁢
1
)
+
d
2
⁡
(
N
Pc
⁢
⁢
2
-
N
Pc
⁢
⁢
1
)
+
θ
m
⁡
(
γ
2
-
γ
1
)
(
10
)
wherein:
HG denotes the height of the gravity center,
d1 denotes the distance between the reference point Pa and the reference point Pb,
d2 denotes the distance between the reference point Pa and the reference point Pc,
NPb2 denotes the normal force at the reference point Pb during the second braking phase,
NPb1 denotes the normal force at the reference point Pb during the first braking phase,
NPc2 denotes the normal force at the reference point Pc during the second braking phase,
NPc1 denotes the normal force at reference point PC during the first braking phase, m denotes the mass of the vehicle,
γ2 denotes the acceleration during the second braking phase,
γ1 denotes the acceleration during the first braking phase, and
θ denotes a corrective value.

### Claim 8 (depends on 7)

Method according to claim 7, wherein θ is selected from 0 for a rigid truck and the term HPb′ (TPb′2-TPb′1), for a vehicle comprising a tractor and a semi-trailer, wherein:
HPb′ denotes the height of the reference point Pb′, when Pb′ corresponds to the fifth wheel,
TPb′2 denotes the tangential force at the reference point Pb′ during the second braking phase, and
TPb′1 denotes the tangential force at the reference point Pb′ during the first braking force.

### Claim 9

A-Method of determination of the height of the gravity center HG (HGr, Hg, HGst) of a vehicle, the vehicle comprising a tractor having at least three axles (Aa, Ab, Ac) and a semi-trailer, wherein 3 reference points Pa, Pb and Pc are predetermined, the method comprising the steps of:
a) determining the tangential forces TAn (TAax, TAbx, TAcx) at all the axles An (Aa, Ab, Ac) of the vehicle, during a first acceleration phase,
b) deducing from the tangential forces TAn (TAax, TAbx, TAcx) determined in step a) the corresponding normal forces NAn (NAax, NAbx, NAcx) during the first acceleration phase,
c) determining the normal force NPb at one of the predetermined reference points Pb, during a first acceleration phase, using the values determined in steps a) and b),
d) repeating steps a), b), and c) at least once during a second acceleration phase, distinct from the first acceleration phase, and
deducing from the preceding steps a), b), c) and d) the height of the gravity center HG (HGr, Hg, HGst) of the vehicle, or an element of the vehicle, by computing the normal forces NPa, NPb and NPc at the 3 predetermined reference points Pa, Pb and Pc, using an algorithm wherein in step a) the tangential forces TAn are determined according to the formula (1): TAnx=QVAnx+FAnx (1) wherein:
TAnx denotes the tangential force at an axle An during a braking period x,
Q denotes the brake factor,
VAnx denotes the braking pressure applied at an axle An during a braking period x, and
FAnx denotes the driving force applied at an axle An during a braking period x.

### Claim 10

Method of determination of the height of the gravity center HG (HGr, Hg, HGst) of a vehicle, or an element of the vehicle, wherein 3 reference points Pa, Pb and Pc are predetermined, the method comprising the steps of:
a) determining the tangential forces TAn (TAax, TAbx, TAcx) at all the axles An (Aa, Ab, Ac) of the vehicle, during a first acceleration phase,
b) deducing from the tangential forces TAn (TAax, TAbx, TAcx) determined in step a) the corresponding normal forces NAn (NAax, NAbx, NAcx) during the first acceleration phase,
c) repeating steps a) and b) at least once during a second acceleration phase, distinct from the first acceleration phase, and
deducing from the preceding steps a), b), and c) the height of the gravity center HG (HGr, Hg, HGst) of the vehicle, or an element of the vehicle, by computing the normal forces NPa, NPb and NPc at the 3 predetermined reference points Pa, Pb and Pc, using an algorithm wherein in step a) the tangential forces TAn are determined according to the formula (1): (1) TAnx=QVAnx+FAnx wherein:
TAnx denotes the tangential force at an axle An during a braking period x,
Q denotes the brake factor,
VAnx denotes the braking pressure applied at an axle An during a braking period x, and
FAnx denotes the driving force applied at an axle An during a braking period x.