DE102017221957A1 - Determining the roof load of a vehicle - Google Patents

Abstract

The invention relates to a method and a system for determining a roof load of a vehicle and for adapting the driving dynamics according to the roof load.

Description

The invention relates to a method and a system for determining a roof load of a vehicle and for adapting the driving dynamics according to the roof load.

In the automotive industry, SUVs are increasingly being developed with a high center of gravity. The high center of gravity of a vehicle leads to a significantly higher risk of tipping and must be prevented by electronic driving stability control systems (ESC). The center of gravity height plays a decisive role in relation to the width of the vehicle. If the vehicle is additionally loaded on the roof, the center of gravity is increased and the lever arm of the roof load to the roll pole is additionally extended. This also increases the risk of tipping.

SUV vehicles are typically equipped with Stability Control Programs (ESP) that prevent rollover during evasive maneuvers (such as fish hooking). These can restrict the vehicle dynamics. Since the vehicles also have to show a safer driving behavior with roof load, but are more critical, tighter ESC control thresholds must be used. In order to minimize the risk of tipping, the driving dynamics of SUVs are then restricted in such a way that the driving pleasure underneath clearly suffers.

Currently in some vehicles switch (roof rack sensors) are installed, which are operated by a mounted roof cross member.

For example, the DE 10 2006 049 986 A1 to mount on the roof of the motor vehicle, an optical sensor which is capable of detecting an object mounted on the roof. The sensor is connected to the ESC control unit to activate tighter ESC control thresholds when a roof mounted item is detected. This further limits the driving dynamics. However, the roof rack sensor can only determine whether a roof rack is installed, the weight and the position of the roof load itself is not determined. If a roof rack is detected, the driving dynamics of the driving stability program must be significantly reduced because of the tilting risk, even if the driver has fixed a roof rack without relevant additional weight (eg an unloaded roof rack).

The roof rack sensors increase the manufacturing costs and lead to a functionally wrong detection, since not the risk of tipping critical roof load is detected, but only the presence of the roof rack. Even if there is no additional roof load apart from the roof rack itself, the narrower ESC control thresholds are activated. In addition, the sensor may also respond due to a user error, e.g. by pressing the switch when the cover flap is not closed in the railing.

It was therefore an object of the invention to provide a method and a system that recognize a roof load even without roof rack sensors and adapt the control thresholds of a driving stability program (ESP) so that a higher driving dynamics is possible without roof load, while in the presence of a roof load the security is guaranteed.

The method according to the invention is based on an estimation of the roll inertia of the vehicle. This depends on the position and weight of the load and allows a conclusion about a roof load. Low roof loads and interior loads can thus be distinguished from critical roof loads, which could lead to a rollover of the vehicle.

Methods have already been proposed for determining the loading state of a vehicle, which use a rolling motion of the vehicle.

The DE 10 2004 035 577 A1 relates to a stabilization device and a method for driving stabilization of a vehicle. In this case, measured values characterizing a driving state of the vehicle are detected. A spectral analysis is applied to the measured values, which correlate with a rolling motion of the vehicle depending on the load state of the vehicle, and a characteristic measure characterizing the load state of the vehicle is output and / or evaluated on the basis of the spectral analysis.

DE 10 2005 048 718 A1 discloses a system and method for dynamically determining a vehicle load and a vertical load distance for use in a vehicle dynamics control system, the control system including a roll rate sensor, a lateral acceleration sensor, a longitudinal acceleration sensor, and a yaw rate sensor. A security system and the sensors are with a Control device coupled. This determines an added mass and the amount of added mass or roll gradient, roll acceleration coefficient and / or roll rate parameter taking into account the added mass and height by roll rate, lateral acceleration, longitudinal acceleration and yaw rate, and controls the safety system in response thereon.

From the DE 11 2008 001 510 T5 A method is known for determining the center of mass height of a vehicle, in which a first group of values is determined that corresponds to the roll angle (φ, φ̇) of the vehicle relative to a reference plane (FIG. zx ) of the vehicle; determining a second set of values associated with the lateral acceleration ( Ay ) of the vehicle; a natural frequency value ( f ) the rolling motion of the vehicle is calculated; a static gain value ( G ) associated with at least one of the values of the first group of values and at least one value of the second group of values; and the center of gravity ( H ) with respect to a vehicle reference point is determined based on the calculated natural frequency value (FIG. f ) and the calculated static gain value ( G ).

According to the invention, the vehicle inertia is estimated by analyzing the rolling differential equation for the vehicle body. It depends on the position and weight of the load and allows a conclusion about a roof load.

If a large mass is fixed on the roof of a vehicle, the inertia around the roll axis changes massively. The roll inertia can be calculated by means of a differential equation using a sensor for roll rate determination in the vehicle. Since both lateral acceleration and the vertical movement of the vehicle are considered in the calculation model, the evaluation is possible in all driving states.

The roll inertia can be determined while driving based on in-vehicle measured variables and it can be concluded so with the help of load detection on a roof load.

The invention relates to a method for determining the roof load of a vehicle and to adapt the driving dynamics according to the roof load. The method according to the invention comprises several steps.

In a first step, the vehicle mass m is determined. The determination of the vehicle mass is a prerequisite for determining the roof load. Alternatively, the load of the vehicle can be determined, ie the mass of the payload. In one embodiment, the determination of the mass takes place with an accuracy of +/- 50 kg. For mass determination, methods known to the person skilled in the art can be used in principle, for example those described in US Pat DE 42 28 413 A1 . DE 197 28 867 A1 or DE 10 2007 000 628 A1 disclosed method.

In a second step, a lateral acceleration a _y of the vehicle and a roll acceleration ω̈ and the wheel contact forces of the vehicle determined.

With the data collected in the second step, the calculation of the roll inertia J of the vehicle takes place in a third step.

bzw. $$J=\frac{1}{\ddot{\omega }}*\left[\frac{S{W}_v}{2}*\left(F_{vl}-F_{vr}\right)+\frac{S{W}_h}{2}\left(F_{hl}-F_{hr}\right)-M_{Stabi,v}-M_{Stabi,h}+M_{ay}\right]$$

wobei

J

das Wankträgheitsmoment;

ω̈

die Wankbeschleunigung;

SW_v

die Spurweite der Vorderachse;

SW_h

die Spurweite der Hinterachse;

F_vl

die Radaufstandskraft vorne links;

F_vr

die Radaufstandskraft vorne rechts;

F_hl

die Radaufstandskraft hinten links;

F_hr

die Radaufstandskraft hinten rechts;

M_Stabi,v

das Stabilisatormoment vorne;

M_Stabi,h

das Stabilisatormoment hinten;

M_ay

das Wankmoment, mit M_ay = m·a_y Δs, worin m die Fahrzeugmasse, a_y die Querbeschleunigung und Δs der Abstand des Schwerpunkts vom Wankpol ist

bedeuten.The estimation of the roll inertia during driving is based on the rolling differential equation, which results from the moment equilibrium. It applies $$\begin{array}{c}0=-J*\ddot{\omega }+\frac{\mathrm{<figure-callout\; id="2"\; label="S\; W\; v"\; filenames="DE102017221957A1\_0005.png"\; state="\{\{state\}\}">S\; </figure-callout>}{W}_v{}_{}}{2}*\left(F_{vl}-F_{vr}\right)+\frac{S{W}_H}{2}\left(F_{Hl}-F_{Hr}\right)-M_{Stabi.v}-M_{Stabi.H}\\ +M_{ay}\end{array}$$

or. $$J=\frac{1}{\ddot{\omega }}*\left[\frac{\mathrm{<figure-callout\; id="2"\; label="S\; W\; v"\; filenames="DE102017221957A1\_0005.png"\; state="\{\{state\}\}">S\; </figure-callout>}{W}_v{}_{}}{2}*\left(F_{vl}-F_{vr}\right)+\frac{S{W}_H}{2}\left(F_{Hl}-F_{Hr}\right)-M_{Stabi.v}-M_{Stabi.H}+M_{ay}\right]$$

in which

J

the roll moment of inertia;

w

the roll acceleration;

SW _v

the gauge of the front axle;

SW _h

the gauge of the rear axle;

F _vl

the wheel contact force front left;

F _vr

the wheel contact force front right;

F _hl

the wheel contact force in the back left;

F _hr

the wheel contact force in the back right;

M _{Stabi, v}

the stabilizer moment at the front;

M _{Stabi, h}

the stabilizer moment behind;

M _ay

the rolling moment, with M _ay = m · a _y Δs, where m is the vehicle mass, a _y the lateral acceleration and .DELTA.s the distance of the center of gravity from the roll pole is

mean.

For the calculation, the wheel contact forces as well as the lateral acceleration and the roll acceleration must also be known. The introduced by the stabilizer moments are calculated axle wise with the help of the compression of the individual wheels and the torsion bar stiffness. The center of gravity is the center of gravity of the unloaded vehicle.

In one embodiment of the method, the roll acceleration ω̈ is determined from a roll rate that is measured by a roll rate sensor present in the vehicle.

In a further embodiment of the method, the lateral acceleration a _y measured by an existing in the vehicle acceleration sensor.

The wheel contact forces are determined depending on the chassis configuration on the deflection of the wheel and suspension characteristics.

In one embodiment of the method, the steps become two and three, ie the measurements and the calculation of the roll inertia J repeated several times to obtain a more accurate value for the roll rate by averaging the results obtained J to obtain. The roll inertia can thus be determined more and more accurately while driving with increasing time. After a few minutes, a detection of 100 kg roof load is possible. Even 60 kg can be differentiated.

The determined sluggishness J is then compared to a threshold. The threshold represents a roll inertia in the presence of a significant roof load, ie a roof load, which has a significant effect on the tilting stability of the vehicle.

The result of the comparison is then forwarded to an in-vehicle electrical stability control (ESC) system. In one embodiment, the ESC is arranged to adjust the parameters of a driving stability program (ESP) according to the result of the comparison. For example, the ESC may limit the driving dynamics if the determined roll inertia J is greater than the threshold value. Alternatively, the ESC may remove vehicle dynamics limitations if the determined roll inertia J is less than the threshold.

Since the total load can be determined and thus the share of the influence on the increase in roll inertia is known, a significant roof load can be detected via the change in the roof load on the increase of the roll inertia directly over the comparison with a threshold value. The threshold is considered as an application parameter and adjusted according to the vehicle.

The results of the roof load determination are transmitted to the electric driving stability control (ESC) while driving. Once the result is available, it can adjust the Driving Stability Program (ESP) parameters accordingly. If there is no significant roof load, it can remove the driving dynamics restrictions while driving so that the driver can drive more dynamically.

Among the advantages of the invention include cost savings by eliminating the sensor and special roof cross member, driving dynamics improvement with low roof loads and avoid user error.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

• 1 eine schematische Darstellung des Kräfte- und Momentengleichgewichts an der Vorderachse eines Fahrzeugs;
• 2 eine schematische Darstellung einer Ausführungsform des erfindungsgemäßen Systems zur Ermittlung der Dachlast eines Fahrzeugs und Anpassung der Fahrdynamik entsprechend der Dachlast.

The invention will be illustrated below with reference to an embodiment and will be further described with reference to the example and the accompanying drawings. It shows.

• 1 a schematic representation of the forces and moment equilibrium on the front axle of a vehicle;
• 2 a schematic representation of an embodiment of the system according to the invention for determining the roof load of a vehicle and adjusting the vehicle dynamics according to the roof load.

1 schematically shows the forces and moment equilibrium by way of example on the front axle of a vehicle. A lateral acceleration a _y affects the focus 11 of the vehicle and generates a rolling motion 13 around the Wankpol 12 , The rolling motion 13 acts a stabilizer torque 14 opposite. The sluggishness 15 results from the moment equilibrium.

bzw. $$J=\frac{1}{\ddot{\omega }}*\left[\frac{S{W}_v}{2}*\left(F_{vl}-F_{vr}\right)+\frac{S{W}_h}{2}\left(F_{hl}-F_{hr}\right)-M_{Stabi,v}-M_{Stabi,h}+M_{ay}\right]$$

wobei

J

das Wankträgheitsmoment 15;

ω̈

die Wankbeschleunigung;

SW_v

die Spurweite der Vorderachse;

SW_h

die Spurweite der Hinterachse;

F_vl

die Radaufstandskraft vorne links;

F_vr

die Radaufstandskraft vorne rechts;

F_hl

die Radaufstandskraft hinten links;

F_hr

die Radaufstandskraft hinten rechts;

M_Stabi,v

das Stabilisatormoment 14 vorne;

M_Stabi,h

das Stabilisatormoment hinten;

M_ay

das Wankmoment, mit M_ay = m·a_y Δs,

bedeuten.It applies $$\begin{array}{c}0=-J*\ddot{\omega }+\frac{\mathrm{<figure-callout\; id="2"\; label="S\; W\; v"\; filenames="DE102017221957A1\_0005.png"\; state="\{\{state\}\}">S\; </figure-callout>}{W}_v{}_{}}{2}*\left(F_{vl}-F_{vr}\right)+\frac{S{W}_H}{2}\left(F_{Hl}-F_{Hr}\right)-M_{Stabi.v}-M_{Stabi.H}\\ +M_{ay}\end{array}$$

or. $$J=\frac{1}{\ddot{\omega }}*\left[\frac{\mathrm{<figure-callout\; id="2"\; label="S\; W\; v"\; filenames="DE102017221957A1\_0005.png"\; state="\{\{state\}\}">S\; </figure-callout>}{W}_v{}_{}}{2}*\left(F_{vl}-F_{vr}\right)+\frac{S{W}_H}{2}\left(F_{Hl}-F_{Hr}\right)-M_{Stabi.v}-M_{Stabi.H}+M_{ay}\right]$$

in which

J

the roll moment of inertia 15 ;

w

the roll acceleration;

SW _v

the gauge of the front axle;

SW _h

the gauge of the rear axle;

F _vl

the wheel contact force front left;

F _vr

the wheel contact force front right;

F _hl

the wheel contact force in the back left;

F _hr

the wheel contact force in the back right;

M _{Stabi, v}

the stabilizer moment 14 forward;

M _{Stabi, h}

the stabilizer moment behind;

M _ay

the rolling moment, with M _ay = m · a _y Δs,

mean.

The rolling moment M _ay results as a product of the vehicle mass m, the lateral acceleration a _y and the distance .DELTA.s of the center of gravity 11 from the Wankpol 12 ,

2 shows a schematic representation of an embodiment of the system according to the invention 10 for determining the roof load of a vehicle and adjusting the driving dynamics according to the roof load. The system 10 includes a unit 20 set up to determine the total mass m of the vehicle is, one unit 30 to determine the roll inertia J of the vehicle and to compare the determined roll inertia with a threshold value is set up; and a system 40 Electric Vehicle Stability Control (ESC), which is designed to adjust the parameters of a Driving Stability Program (ESP).

The unit 20 determined total mass m of the vehicle is to the unit 30 transmitted and goes into the determination of the roll inertia J on. unit 30 receives measurement data of at least one roll rate sensor present in the vehicle 31 and determines therefrom a roll acceleration, which is used to determine the roll inertia J received the vehicle. unit 30 also receives measurement data of at least one lateral acceleration sensor present in the vehicle 32 also involved in the determination of stumbling J of the vehicle.

After determination of the roll inertia J compares unit 30 this with a threshold that represents a roll inertia in the presence of a significant roof load and passes the result of the comparison to the ESC 40 continue.

The ESC 40 is adapted to adjust the parameters of a driving stability program (ESP) according to the result. Is the determined Wank inertia J greater than the threshold value, the ESC restricts the driving dynamics, ie the control thresholds of the ESP are narrowed and an intervention takes place, for example, even at lower lateral accelerations. Is the determined Wank inertia J less than the threshold, the ESC removes driving dynamics limitations. For example, the preset limits for driving with roof load in the ESP can be overridden if there is no significant roof load. This allows the driver to drive more dynamically.

LIST OF REFERENCE NUMBERS

10

System for roof load determination and adaptation of vehicle dynamics

11

main emphasis

12

rolling pole

13

Rolling motion ω

14

Stabilizer _torque M _{Stabi, v}

15

Wankträgheit J

20

Unit for determining the vehicle mass or mass of the load

30

Unstacking unit J of the vehicle and comparison with a threshold

31

roll rate

32

Lateral acceleration sensor

40

ESC

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006049986 A1 [0005]
• DE 102004035577 A1 [0010]
• DE 102005048718 A1 [0011]
• DE 112008001510 T5 [0012]
• DE 4228413 A1 [0017]
• DE 19728867 A1 [0017]
• DE 102007000628 A1 [0017]

Claims (10)

Method for determining the roof load of a vehicle and for adapting the driving dynamics in accordance with the roof load, comprising the steps of a) determining the vehicle mass m; b) determining a transverse acceleration a _{y of} the vehicle, a rolling acceleration ω̈ and the wheel contact forces (F _vl , F _vr , F _hl , F _hr ) of the vehicle; c) calculating the roll inertia J of the vehicle; d) comparing the determined roll inertia J with a threshold value; (e) transmission of the result of the comparison to an in-vehicle electrical stability control system (ESC). Method according to Claim 1 in which the roll acceleration ω̈ is determined from a roll rate which is measured by a roll rate sensor present in the vehicle. Method according to Claim 1 or 2 in which the lateral acceleration a _{y is} measured by an acceleration sensor provided in the vehicle. Method according to one of Claims 1 to 3 in which steps b) and c) are repeated several times in order to obtain a more accurate value for the roll inertia J by averaging the results obtained. Method according to one of the preceding claims, in which the ESC is set up to adapt the parameters of a driving stability program (ESP) to the result of the comparison of the determined rolling inertia J with a threshold value. Method according to Claim 5 in which the ESC limits the driving dynamics when the determined roll inertia J is greater than the threshold value. Method according to Claim 5 in which the ESC suspends driving dynamics restrictions if the determined roll inertia J is less than the threshold value. System (10) for determining the roof load of a vehicle and for adapting the driving dynamics according to the roof load, comprising a) a unit (20) arranged to determine the total mass m of the vehicle; b) a unit (30) adapted to determine the roll inertia J of the vehicle and to compare the determined roll inertia with a threshold value; and c) an electric driving stability control (ESC) system (40) adapted to adjust the parameters of a driving stability program (ESP); wherein the unit (30) is adapted to communicate with the unit (20) and the ESC (40) to query the total mass m of the vehicle and pass the result of the comparison of the determined roll inertia with the threshold to the ESC (40) ; and wherein the ESC (40) is adapted to adjust the parameters of a driving stability program (ESP) according to the result. System (10) after Claim 8 in which the unit (30) for determining the roll inertia J of the vehicle and for comparing the determined roll inertia with a threshold value is arranged to receive data from at least one roll rate sensor (31) present in the vehicle and to determine therefrom a rolling acceleration. System (10) after Claim 8 or 9 in which the unit 30 for determining the roll inertia J of the vehicle and for comparing the determined roll inertia with a threshold value is set up to receive and process data of at least one transverse acceleration sensor 32 present in the vehicle.

Images