EP2855228A1

EP2855228A1 - Method of detecting an untimely acceleration of a motor vehicle

Info

Publication number: EP2855228A1
Application number: EP13723837.4A
Authority: EP
Inventors: Vincent DE FLAUGERGUES; Stephane Camp; Cecile Thenegal; Marco Pengov
Original assignee: Peugeot Citroen Automobiles SA
Current assignee: PSA Automobiles SA
Priority date: 2012-05-24
Filing date: 2013-04-19
Publication date: 2015-04-08
Also published as: CN104470783A; CN104470783B; FR2990916B1; WO2013175093A1; FR2990916A1

Abstract

The invention relates to a method of detecting an untimely acceleration of a motor vehicle in which a deviation (e) between a theoretical acceleration and an actual acceleration is determined and an alert cue (w2) is despatched if the deviation (e) is greater than a detection threshold (s), characterized in that the method comprises a phase of resetting at least one parameter, performed when the vehicle is in a situation of operating with no demanded engine torque. The invention also pertains to a vehicle comprising at least one computer configured to implement the method of the invention.

Description

METHOD FOR DETECTING INTEMPESTIVE ACCELERATION OF A

MOTOR VEHICLE

Technical field of the invention

The present invention relates to the safety of motor vehicles.

The invention relates more particularly to a method for detecting inadvertent acceleration of a motor vehicle.

Technological background

Untimely acceleration on a motor vehicle is a dreaded event that can jeopardize the safety of the occupants of the vehicle if it occurs. Being able to monitor and identify the occurrence of such an event is therefore essential.

An acceleration is considered untimely when the vehicle accelerates while the driver does not press the pedal, or more generally, when the vehicle accelerates more than the driver has requested. The known methods of determining whether an acceleration is untimely consist in detecting an over-acceleration by one of the following monitoring means: monitoring of an engine torque in a situation of raised foot or more generally in situation without a request for torque engine: it is then necessary to check that there is no injection during this situation;

- Continuous monitoring of the motor torque: it is then a question of comparing the torque demanded with the couple achieved;

- Continuous monitoring of vehicle acceleration: this involves comparing the theoretical acceleration of the vehicle, estimated from the engine torque demanded by the driver at the actual acceleration, calculated for example by deriving the measured speed from the vehicle.

However, these monitoring means have certain disadvantages:

Carrying out only engine torque monitoring in situations without requested engine torque is limited: it is limited to certain vehicle life situations. In addition, detecting an injection in a situation without engine torque required, for example, in a so-called "stand-by" situation, is not symptomatic of a defect: this situation can occur in a normal mode of operation such as, for example, injections for heating a catalyst.

Continuous monitoring of the engine torque is more difficult for some types of engines, such as gasoline engine stratified load, torque estimation is difficult in some cases.

Continuous monitoring of vehicle acceleration can be applied to any type of vehicle. However, the effectiveness of this method depends in particular on the precision of the estimate of the deviations:

- between the actual mass of the vehicle, which is unknown, and the mass taken for reference,

- between the actual friction coefficient of the brake pads, which is unknown, and the coefficient of friction taken for reference.

The larger these deviations, the more the estimation of the theoretical acceleration is distorted. If necessary, there are risks of non-detection, if the theoretical acceleration is overestimated, or of false alarm, if the theoretical acceleration is underestimated.

An object of the present invention is to solve one or more of these disadvantages.

The invention thus relates to a method for detecting an inadvertent acceleration of a motor vehicle in which a difference between a theoretical acceleration and a real acceleration is determined and an alert information is sent if the difference is greater than one. detection threshold, characterized in that the method comprises a resetting phase of at least one parameter taking place when the vehicle is in an operating situation without requested engine torque. Indeed, this operating situation makes it possible to make reliable readjustments and thus to improve the accuracy of the estimate of the difference

Preferably, the registration phase of at least one parameter comprises the registration of the vehicle mass and / or the coefficient of friction of the brake pads of the vehicle. More preferably, the registration of the mass of the vehicle is performed for additional registration conditions comprising: no support on the brake pedal, a substantially zero slope. Preferably again the registration of the coefficient of friction of the brake pads is carried out for additional registration conditions comprising: a pressure on the brake pedal, a substantially zero slope.

In a variant, the additional resetting conditions include a time required in the operating situation without requested motor torque, between a minimum duration and a maximum duration. Preferably, the time required in operating situation without motor torque requested is between 300 milliseconds and 2 seconds.

Preferably, the vehicle mass and / or the coefficient of friction is averaged over the required time.

Preferably, the deviation is determined when the vehicle is in an operating situation with requested engine torque.

In a variant, when the vehicle is in the operating situation without requested engine torque, the injection parameters are monitored and a warning signal is emitted in the event of detection of an abnormal injection of fuel.

The invention also relates to a vehicle comprising at least one computer configured to implement the method of the invention.

Brief description of the drawings

Other features and advantages will appear on reading the following description of a particular embodiment, not limiting of the invention, with reference to the figures in which:

FIG. 1 is a schematic representation of the logical structure of the method for detecting an inadvertent acceleration of the invention.

- Figure 2 is a schematic representation of the calculation of the difference between theoretical acceleration and actual acceleration.

- Figure 3 is a schematic representation of the calculation of the registration of the vehicle mass or coefficient of friction of the brake pads. - Figure 4 is a schematic representation of the calculation of the mass of the vehicle.

- Figure 5 is a schematic representation of the calculation of the coefficient of friction of the brake pads.

detailed description

FIG. 1 presents, in the form of a functional block, the method of detecting an inadvertent acceleration of the invention. The method can be implemented by at least one motor vehicle computer, the computer receiving the appropriate information from sensors or estimators that includes the vehicle. In this method, the block 1 executes when the vehicle is in a situation where the requested engine torque is zero while the block 2 runs when the requested engine torque is non-zero. The execution of the appropriate block 1 or 2 is decided for example by the receipt of a logical information t taking for example the value 1 in the situation of engine torque demanded zero and 0 in the other situation.

Blocks 1 and 2 use information from various sources:

a first group of signals, a, originating from the sensors and motor control designated A, such as, for example, the speed sensor.

a second group of signals, b, from the vehicle sensors and ground link designated B,

a first group of parameters, c, from a memory C accessible for reading and writing. Parameters c relate to the mass of the vehicle and the coefficient of friction of the brake pads,

a second group of parameters, d, coming from a memory D accessible in read-only mode.

In the remainder of the specification and in FIGS. 2 to 5, the signals of the different groups a, b, c, d are made distinct by an index.

Block 1 comprises a monitoring block 10 of the injection parameters and a readjustment block 1 1 of the parameters C for reading and writing: the mass of the vehicle and the coefficient of friction of the brake pads. Block 1 emits a warning signal w1 if an abnormal injection of fuel is detected by block 10. Indeed, such an abnormal injection of fuel could be the cause of untimely acceleration of the vehicle. For example, injection parameters such as data can be monitored. injection angles, injection time, engine speed to check the plausibility of a motor torque of about zero.

Block 2 includes:

a calculation block 21 of the difference, e, between the theoretical acceleration, γ _Λ , and the real acceleration γ _τ .

The theoretical acceleration can be estimated by applying the Fundamental Principle of Dynamics (or by acronym PFD) by the following principal relation:

<V -

J th

And or :

C _mof is the specified motor torque requested. More specifically, the motor torque indicated requested corresponds to the engine torque from the calculation chain of the setpoint (or request) of torque beginning with the Interpretation Willing Conductor which determines the torque at the crankshaft requested by the driver, modulated to take in account the motor losses (belt drive, pumping ...), the external demands of torque (eg esp, speed regulator, gearbox), the approval requirements ... C _{losses word} is the couple of motor losses including, for example, pump losses, drive losses of the alternator belts and accessories, (corresponding to the difference between the indicated engine torque and the actual engine torque) m _veh is the mass of the vehicle,

6 _slope is the slope,

_tmns ri = JJ _po _"r JJ _B v ^{is the} transmission power output comprising a differential bridge and a respective output of gearbox _η ροηί and _η Βν. ^r tmn _S ^{= r} _P onf ^r Bv ^{is the} transmission input, the product of the bridge ratio, r _bridge , and gearbox ratio, r _BV .

r _wheel is the wheel radius,

F _x, bearing ' ^F aero ^{are the} resistant outer forces, respectively, rolling friction and aerodynamic drag, Cfrein = Pfrein ■ μ, _Γβ ί _η ■ Sfrein ■ Rfrein is the brake torque, produced by the brake pressure, _brake , platelet surface, s the radius at the center of the pads, R _brake and a coefficient of friction μ _{ηίη of the brake pads.

Jiot = ^m v _e _ra hr u _e ² + trans-r, ² rans -Jmot is the total inertia of the vehicle, with J _word, motor inertia.

The actual acceleration there are _r \, in turn, calculated from at least one measurement of vehicle dynamics. For example, the actual acceleration can be advantageously calculated by _{deriving the} measured speed of the vehicle, v _veh :

Block 2 still includes:

a calculation block 22 of a detection threshold, s, which varies according to the gearbox ratio of the vehicle,

a comparison block 20 of the difference, e, at the detection threshold, s, emitting a warning signal w2 in the case where the difference e is greater than the detection threshold s.

The detection threshold, s, is the tolerated difference between the theoretical acceleration ^ _i¾ and the real acceleration _r of the vehicle. In the case where it is desired to detect an acceleration difference due to an over-torque, in other words a motor torque overshoot AC, the detection threshold, s, by application of the Fundamental Principle of Dynamics is expressed in function of the report of box engaged by the relation:

I trans trans r wheel

The detection threshold, s, can be chosen so as to detect an engine over-torque of 25 Nm.

As shown more precisely in FIG. 2, the block 21 comprises:

a block 210 for estimating the motor loss torque C _word _losses . The block 210 uses in input data the engine speed a2.

a block 21 1 for estimating the torque transmitted to the wheels, taking as input the motor loss torque, C _word determined at block 210, the requested torque, C _word designated a1 on FIG. 2, and additional parameters such as the gear ratio b _BV designated b5 in FIG. 2 or the position of the clutch pedal b6.

a block 212 for estimating the rolling friction, F _{X bearing} , from the mass of the vehicle, m _veh designated c1 in FIG. 2.

a block 213 for estimating the brake torque, _ra "_> from the coefficient of friction of the brake pads and the braking pressure, p _brake , designated respectively c2 and b4 in FIG.

a block 214 for estimating the aerodynamic drag force, F _aero , taking as input the speed of the vehicle, v _veh , designated b1 in FIG. 2.

a block 215 for calculating the real acceleration, γ _τ , taking as input the speed of the vehicle, v _veh , designated b1 in FIG. 2.

a slope calculation block 216, 9 _slope , by comparison of the longitudinal acceleration, b2 and the real acceleration, γ _Γ , calculated at block 215. The slope _slope can be estimated using the relation

boy Wut. sin (0 _slope + 6 _attitude ) = ¾ _inertia n _e - ε (ν _νθη ). γ _Γ - _centrifugal

With:

ainertieiie ^'■ the longitudinal acceleration, denoted b2 in Figure 2.

Θ plate ^'■' attitude angle approximated from the actual acceleration, _γ τ, the vehicle and a coefficient of proportionality k:

® plate ^-

acentrifu _g e ^'■ the centrifugal acceleration which can be for example calculated from the steering wheel angle 9 of el _wheel geometrical characteristics such as wheel base, E, the angle coefficient gear wheels / steering wheel angle, _{steering wheel} D, the x-position of the sensor x _ur , (with x = 0 on the rear wheels) by a relation of the form:

, _ ^v veh. ° wheel

centrifugal ^ ₂ sensor

V ^ flying J

This centrifugal acceleration can also be calculated from a yaw rate sensor of a trajectory control device (commonly known as ESP). This Slope estimation can be disabled in some cases such as unstable signals, slip detection, braking. The slope 9 _slope is then frozen at its last value. Block 21 further includes:

a block 217 for calculating the theoretical acceleration, _th , by applying the Fundamental Principle of Dynamics detailed above, taking as input the results of the blocks 21 1, 212, 213, 214, 216 as well as the mass of the vehicle, m _veh designated c1 in FIG.

a block 218 for comparing the theoretical acceleration, _th , obtained at block 217 and the real acceleration, γ _τ , calculated at block 215, and determining at output the difference e between the two computed accelerations.

Concerning the block 1 1 of registration, as shown more precisely in Figure 3, it comprises:

- a block 1 10 of checking that the conditions to operate the resetting of the _veh mass m of the vehicle, designated c1 of Figure 3 or of the friction coefficient μ _{τήη brake pads are met. This block 1 10 also takes parameters such as the slope _slope estimate 9, the gear ratio b _BV designated b5 in FIG. 3, the position of the clutch pedal b6, the position of the pedal of brake b7, the logical information t of torque requested.

a counting block 1 1 1 of a duration T during which conditions for performing the registration are combined. During this period T the actual acceleration variation, γ _τ , is recorded.

a calculation block 1 12 either of the vehicle mass _m¾ or of the coefficient of friction μ _{ηίη of the brake pads.

Block 1 1 may also comprise a block 1 13 of calculating an average over the duration T is the mass m _ve¾ of the vehicle or the coefficient of friction μ _{ηίη brake pads, from the average change in the acceleration over the entire duration T. This makes it possible to filter the estimate of the parameter). Block 13 may also include a validation step of the value coherence calculated during this registration phase with respect to their assumed value range and an outlier estimate, for example a mass less than the empty mass, can be discarded which reinforces the reliability of the process. Thus we can consider that the estimate of the coefficient of friction, μ _{ηίη , is valid if it is in a range between 0.1 and 0.55. Similarly, it can be considered that the estimate of the mass m _veh is valid if it is much higher than the empty mass.

With regard to the conditions to be met in order to perform the registration of the vehicle mass m _veh , this is done when the vehicle is in torque situation requested null, and under the following additional conditions:

- no support on the brake pedal,

- Slope 9 _slope substantially zero, preferably less than 1 ° in absolute value.

a duration T required in a requested torque situation of zero, greater than a minimum threshold, t _min , which corresponds to a minimum duration allowing stabilization and confirmation of the zero demand torque situation. Advantageously, the minimum threshold, t _min , is approximately 300 ms.

a duration T required in a requested torque situation of zero, less than a maximum threshold, t _max . This maximum threshold corresponds to a compromise to be found between the number of points to be recorded, having enough deceleration and at the same time having a small variation in the rolling friction, which depends on the speed. Advantageously, the maximum threshold, t _max , is for example 2 seconds.

Concerning the conditions to be met in order to make the adjustment of the coefficient of friction μ _{τήη of the brake pads, this is done when the vehicle is in torque situation requested null, and under the following additional conditions:

- pressing on the brake pedal,

- slope 9 _slope substantially zero,

a duration in the requested torque situation of zero, greater than a minimum duration, t _min , for example of 300 ms,

a duration in a requested torque situation of zero, less than a maximum duration, tmax, for example 2 seconds.

Knowing the value of the acceleration over the given duration T, here between the minimum duration t _min and the maximum duration, t _max , and from the fundamental principle of the Dynamic, we deduce then either the vehicle mass, m _veh (under these conditions, the engine torque, C _word, torque brake, _c> ^Ia slope 9 _slope are zero) or torque brake the C ^and therefore the coefficient of friction, p _brake (under these conditions, the engine torque, C _word , the slope, 9 _slope , are zero). The mass of the vehicle, m _veh , or the coefficient of friction, _brake can then be averaged over the duration T (block 1 13).

Figures 4 and 5 respectively show the calculations carried out by the block 1 12 for determining the mass of the vehicle, m _veh designated c1 in said figures and the coefficient of friction of the brake pads, p _brake , designated c2 in said figures.

In FIG. 4, the block 1 12 comprises:

a block 1 120 for estimating the motor loss torque, C _losses, _word . The block 1 120 may include a map of losses by pumps and losses due to the drive of accessory and alternator belts. The block 1 120 uses as input the engine speed a2. Block 1 120 is equivalent to block 210.

a block 1 121 for estimating the motor loss torque, C _word _losses , transmitted to the wheels. Block 1 121 uses as input the transmission ratio / gear ratio b _BV designated b5 in Figure 4 or the position of the clutch pedal b6 (input not shown). Block 1 121 is equivalent to block 21 1).

- A block 1 122 for estimating the rolling friction, F _{X bearing} , depending on the mass of the vehicle m _veh . The rolling friction can be expressed in the form:

Fx.roll = (& + bV _yeh ) .ΓΠ _νθη

, with a and b constants.

a block 1 124 for estimating the aerodynamic drag force, F _aero , taking as input the speed of the vehicle, v _veh , designated b1 in FIG. 4. The aerodynamic drag force can be expressed in the form:

1 2

Faero ⁼ -P - ^ - C _x .V _yeh with: p density of the air, S reference surface of the vehicle, Cx coefficient of drag. a block 1 126 for calculating the real acceleration, _r , obtained by _{deriving the} vehicle speed, v _veh , designated b1 in FIG. 4.

a block 1 125 for calculating the slope estimate, 9 _slope , by applying the already detailed relation:

g.sin (6 _slope + 6 _attitude ) = _inertiaNe - e (v _veh ) _.Y _r - _centrifugal

a block 1 127 for calculating the mass of the vehicle m _veh , designated c1 in FIG. 4, from the _fundamental principle of the dynamics and the inputs of the blocks 1 121, 1 124, 1 125, 1 126 which is expressed then in the form: - (. r _r oue ² -Y _r + (a + bv _veh) + g sin (9 _slope)) =

With an estimate of the rolling friction, F _{X bearing} , depending on the vehicle mass m _veh . The rolling friction can be expressed in the form: F _{x r0U | ement} - (a + b. V _veh ) .m _veh

, with a and b constants.

In FIG. 5, the block 1 12 repeats the blocks 1 120, 1 121, 1 124, 1 125 described in the presentation of FIG. 4. As FIG. 5 again shows, the block 1 12 furthermore comprises:

a block 127 'of calculation of the brake torque, _ra "_> from the Fundamental Principle of the

Dynamic and inputs of blocks 1 121, 1 122, 1 124, 1 125, 1 126.

a coefficient of friction calculation block, μ _{τήη , designated c2 in FIG.

1 123 takes as input the brake torque, c determined at block 1 127 'and the brake pressure, p _brake (not shown).

The invention has the advantage of allowing exploiting the situation in which no torque is required, for example because the driver does not press the accelerator pedal:

- to continuously monitor the acceleration of the vehicle, to reduce these parametric uncertainties and thus to reduce the risk of false detection and non-detection.

- to guarantee the dependability requirements for a dreaded event of untimely acceleration.

The invention allows a simpler calibration of the estimators and a transversality of the process, that is, the process can be easily adapted from one vehicle to another.

Claims

claims

1. A method for detecting an inadvertent acceleration of a motor vehicle in which a difference (e) between a theoretical acceleration ( _th ) and a real acceleration (γ _Γ ) is determined and an alerting information (w2) is sent if difference (e) is greater than a detection threshold (s), characterized in that the method comprises a step of resetting at least one parameter occurring when the vehicle is in an operating situation without requested engine torque.

2. Detection method according to claim 1, characterized in that the registration phase of at least one parameter comprises the registration of the mass of the vehicle (m _veh ) and / or the coefficient of friction {μ _ίΓβίη ) of the plates of brake of the vehicle.

3. Method according to claim 2, characterized in that the registration of the mass of the vehicle (m _veh ) is performed for additional registration conditions comprising: no support on the brake pedal, a slope {9 _slope ) substantially nothing.

4. Method according to claim 2 or claim 3, characterized in that the registration of the coefficient of friction (μ _ίΓβίη ) brake pads is performed for additional registration conditions comprising: a brake pedal, a slope (0 _slope ) substantially zero.

5. Method according to claim 3 or claim 4, characterized in that the additional resetting conditions comprise a duration (T) required in operating situation without requested motor torque, between a minimum duration (tmin) and a maximum duration ( t _max ).

6. Method according to claim 5, characterized in that the duration (T) required in the operating situation without requested motor torque is between 300 milliseconds and 2 seconds.

7. Method according to claim 5 or claim 6, characterized in that the vehicle mass (m _veh ) and / or the coefficient of friction {μ _ίΓβίη ) is averaged over the duration

(T) required.

8. Method according to any one of the preceding claims, characterized in that the determination of the difference (e) occurs when the vehicle is in an operating situation with engine torque requested.

9. Method according to any one of the preceding claims, characterized in that when the vehicle is in the operating situation without requested engine torque, the injection parameters are monitored (10) and an alert signal is emitted (w1 ) if an abnormal fuel injection is detected.

10. Vehicle comprising at least one computer configured to implement a method according to any one of the preceding claims.