WO2008152256A2

WO2008152256A2 - Diagnostic device for an after-the-fact analysis of the behaviour of a motor vehicle and corresponding method

Info

Publication number: WO2008152256A2
Application number: PCT/FR2008/050718
Authority: WO
Inventors: Cédric Chassagnol; Stéphane Guegan
Original assignee: Renault S.A.S.
Priority date: 2007-05-25
Filing date: 2008-04-22
Publication date: 2008-12-18
Also published as: EP2153416A2; WO2008152256A3; JP2010528308A; JP5306335B2; EP2153416B1; FR2916535B1; FR2916535A1

Abstract

The invention relates to a diagnostic device for an after-the-fact analysis of the behaviour of a four-wheel-steer motor vehicle, comprising an assembly of sensors capable of measuring chosen parameters representative of the state of the motor vehicle. It also comprises at least one main memory, a first assembly of sensors (21, 23) capable of measuring a first set of parameters, a buffer memory (25) capable of storing the said first set of parameters when the angular speed of deflection of the rear wheels and the speed of the motor vehicle respectively exceed a given threshold, the buffer memory being coupled to the said main memory via transfer means capable of transferring the data from the buffer memory (25) to the main memory (31) when a predetermined event (EV20) occurs while the motor vehicle operates in nominal mode. Reference: figure 2

Description

DIAGNOSTIC DEVICE FOR POSTERIORI ANALYSIS

BEHAVIOR OF A MOTOR VEHICLE AND

CORRESPONDING METHOD

The present invention relates to a motor vehicle with four steering wheels. More specifically, the invention relates to the diagnostic means used for such vehicles.

Conventionally, the diagnostic means make it possible to analyze a situation in cases where a vehicle failure has been detected during taxiing. In this case, the vehicle has passed into a safe mode called "degraded mode".

An error code (called "DTC" by the skilled person for "Diagnostic Trouble Code" in the English language) has been recorded and a backup of certain parameters such as the steering wheel angle or the speed of the motor vehicle, has been done at the time of the breakdown. These diagnostic means are therefore effective to know the circumstances and the origin of a failure occurred during taxi and detected by the system. On the other hand, in the case where a driver complains of the behavior of the motor vehicle without any failure having been detected, these means of diagnosis do not allow any analysis a posteriori. The object of the invention is to improve the diagnosis of the motor vehicle, especially when no particular failure has occurred.

The invention proposes to define a diagnostic system for a motor vehicle four-wheel steering to analyze the evolution of the parameters representative of the operation of the motor vehicle whatever the mode of operation of the vehicle.

The invention also proposes to define a diagnostic method for a motor vehicle with four-wheel steering.

For this purpose, the invention relates to a diagnostic device for a posteriori analysis of the behavior of a four-wheeled motor vehicle, comprising a set of sensors able to measure selected parameters representative of the state of the motor vehicle . According to a general characteristic of the invention, the device further comprises at least one main memory, a first set of sensors capable of measuring a first set of parameters, a buffer memory capable of storing said first set of parameters when the angular speed of steering of the rear wheels and the speed of the motor vehicle respectively exceed a given threshold, the buffer memory being coupled to said main memory via transfer means able to transfer the data from the buffer memory to the main memory when a predetermined event occurs then that the motor vehicle operates in nominal mode. In other words, it is possible to store in a main memory parameters representative of the state of the motor vehicle while the motor vehicle is still in nominal mode.

This has the advantage of being able to analyze the evolution of these parameters when a driver detects an abnormal situation without however the vehicle has gone into degraded mode.

The inventors have realized that it could be considered that a situation was abnormal when the steering angle and the speed of the motor vehicle respectively exceeded a single given, preferably when the angular speed of steering of the rear wheels is greater than 17s. and that the speed of the motor vehicle is greater than 20 km / h.

By way of example, said event may be representative of the limit situations from the point of view of the dynamics of the motor vehicle.

In this case, this event representative of the limit situations from the point of view of the dynamics of the motor vehicle is chosen from the triggering of a trajectory correction system, the end of a braking action on a fractional Mu-coefficient surface, the triggering of an airbag, a steering speed of the rear wheels greater than another given threshold, a regulation action by an anti-lock system of the wheels.

The parameters of the first set may be chosen from the steering wheel angle of the motor vehicle, the speed of the steering wheel of the motor vehicle, the speed of the motor vehicle, the steering angle of the rear wheels of the motor vehicle, the steering setpoint of the rear wheels. of the motor vehicle, the Static steering setpoint of the rear wheels of the motor vehicle, the dynamic steering setpoint of the rear wheels of the motor vehicle, the angular setpoint of the rear wheels relative to a braking on a surface with a Mu-fractionated grip coefficient, all the parameters mentioned above being measured at different times before the storage moment in the buffer memory, and also selected from the mileage of the motor vehicle at the time of storage and the number of times that a storage is performed in the buffer.

The device may furthermore comprise transmission means capable of transmitting the data stored in the main memory to means of analysis external to the motor vehicle, so that the analysis means reconstitute the steering setpoint at the different storage times in the main memory. the buffer memory, for checking the consistency of the reconstituted steering setpoint with the values of the steering wheel angle and the speed of the motor vehicle taken at these different times.

Furthermore, said event may be representative of the limiting situations from the point of view of the operation of the motor vehicle, for example a stopping of the thermal engine while driving.

Furthermore, the device may further comprise at least one auxiliary memory capable of recording parameters representative of the state of the motor vehicle when a failure occurs and the motor vehicle operates in degraded mode.

According to another aspect of the invention, there is provided a diagnostic method for a posteriori analysis of the behavior of a four-wheeled motor vehicle. Said method comprises a step of measuring selected parameters representative of the state of the motor vehicle.

According to a general characteristic of this other aspect of the invention, the measuring step comprises a first measurement of a first set of parameters. Said measuring step is followed by a step of storing the first set of parameters when the rear wheel angle of rotation and the speed of the motor vehicle respectively exceed a given threshold and a main step of recording the first set of parameters. stored parameters, when a predetermined event occurs while the motor vehicle is operating in nominal mode.

Furthermore, the method may further comprise an auxiliary recording step, when a failure occurs and the motor vehicle operates in degraded mode.

The present invention will be better understood on reading the detailed description of an embodiment and an implementation mode taken by way of examples and therefore in no way limiting, the latter being illustrated by the appended drawings, in which: FIG. 1 illustrates an embodiment of a diagnostic device according to the invention; FIG. 2 illustrates more precisely one embodiment of a module of the diagnostic device, this module being associated with the situations considered as limits from the point of view of the dynamics of the vehicle; FIG. 3 represents a mode of implementation of the operation of the module illustrated in FIG. 2; FIG. 4 represents an embodiment of another module concerning the situations considered as being limited from the point of view of the operation of the system; FIG. 5 illustrates an embodiment of another module associated with accident situations with the triggering of airbags.

In Figure 1, there is shown an embodiment of a diagnostic device for a posteriori analysis of the behavior of a motor vehicle four-wheel steering. This device is referenced 1.

In this embodiment, the device 1 comprises three modules 10, 20 and 40, each able to focus on a particular type of situation.

The module 10 relates to the situations considered as limits from the point of view of operation of the motor vehicle, without however that it is in degraded mode. An example of such a situation is the stopping of the thermal engine of the vehicle while driving. The role of this module 10 will then be for example essentially to memorize the occurrence of such a situation as well as the value of the mileage at its appearance to be able to correlate with a complaint of the driver a posteriori. This module 10 will be described in more detail below.

The module 20 relates to the situations considered as limits from the point of view of the dynamics of the motor vehicle. These include for example the triggering of a trajectory correction system ("ESP" for

"Electronic Stability Program" in English), or the end of a braking action on a split-Mu surface. In this case, the role of the module 20 is to memorize the information that will allow a posteriori analysis of the consistency between: the steering wheel angle, the speed of the motor vehicle and the steering setpoint of the rear wheels on the one hand, the rear wheel steering setpoint and the rear wheel steering measurement, on the other hand. This module 20 will be described more precisely below.

The third module 40 relates to accident situations with triggering airbags. The vehicle can be in this case in degraded mode. The recording in this case is only related to the triggering of the airbag. The role of this module 40 is then to memorize the information that will analyze the circumstances of the accident. This module will be described in more detail below.

In this embodiment, the diagnostic device 1 comprises three modules for managing three different types of situations. However, in another embodiment, the device may comprise only the module 20 or the module 20 and the module 10. The configuration of the diagnostic device described here is not limiting.

Referring now to Figure 2 which more specifically illustrates the module 20, that is to say the module on the situations considered as limits from the point of view of the dynamics of the motor vehicle. The module 20 comprises a set of sensors 21 able to measure the steering wheel angle, the angular speed of the steering wheel, the speed of the motor vehicle, the steering angle of the rear wheels, the setpoint of the steering angle of the wheels. rear, the static component of the steering angle setpoint of the rear wheels, the dynamic component of the steering angle setpoint of the rear wheels, and the rear wheel angle setpoint for braking on a surface with a d Mu-fractionated adhesion. The angular speed of the steering wheel can be obtained by deriving the measurement of the steering wheel angle and filtering at 2Hz.

The measurements of these various parameters are stored for 250 ms in a set of memory 22 respectively associated with each of the sensors 21. Moreover, the module 20 comprises another sensor 23 for measuring the mileage at a time t, as well as a counter of occurrences 24 able to count the number of times that a storage of the parameters measured by the sensors is performed in a buffer memory 26 which will be described in more detail below.

A comparator 25 is coupled to the output of the memories 22 and to the output of the sensor 23 and the counter 24 via connections 25b. This comparator

25 also receives on another input, via a connection 25a, the steering speed of the rear wheels of the motor vehicle Br and the speed of the motor vehicle VV.

The steering speed of the rear wheels of the motor vehicle can be obtained by deriving the measurement of the steering of the rear wheels by filtering at 4 Hz.

Comparator 25 compares each of these two values with a chosen threshold. In this example, these thresholds are respectively equal to 1% and 20 km / h.

Indeed, the inventors have demonstrated that when the steering angle of the rear wheels Br and the speed of the vehicle VV are respectively greater than each of these two values, the motor vehicle can end up in potentially dangerous situations if the steering wheels is unwanted (that is, due to a system failure) and the following scenarios occur, namely:

- a triggering of the trajectory correction system (ESP), the end of a braking action on a Mu-split surface ("Mu split" in English), the action of an ABS type system "Anti Blocking System "or, - the triggering of an airbag less than 15 seconds after the values of the speed of the motor vehicle and the speed at the steering of the rear wheels have exceeded the aforementioned thresholds,

- the appearance of an atypical situation such as low steering wheel activity and significant rear wheel steering.

The comparator 25 is coupled to a buffer memory 26 via connections 27. The buffer memory 26 is able to store six different situations in this example. The seventh situation to be memorized overwrites the first situation. If the comparator 25 observes that a steering speed of the rear wheels is greater than 1 ° / s and that the speed of the vehicle is greater than 20 km / h, then the data measured by the sensors 22, 23 and 24 are stored in one of the six compartments 28 of the buffer memory 26.

This storage is controlled by a control block 29 and takes place at a time t, via a connection 29b.

The parameters measured by the sensors 22 are stored in the buffer memory 26 at times t, t-50 ms, t-100 ms, t-150 ms, t-200 ms. The difference between two successive memories Δtbuf is transmitted via a connection 30 to the comparator 25. In fact, according to a preferred embodiment, if the comparator detects a steering speed of the rear wheels Br and a speed of the vehicle VV greater than the aforementioned thresholds, the storage in the buffer memory 26 takes place only if the duration Δtbuf is greater than 250 ms.

The buffer memory 26 is coupled to a main memory 31 (for example an E2prom) comprising two separate storage areas 32 and 33. The transfer between the two memories 26 and 31 is performed via transfer means.

34.

The duration between two transfers to the main memory 31, Δtmem, is sent via a connection 35 to the means 29.

The control means 29 also receives a signal warning of an event EV20 via a connection 29a, namely: the triggering of a trajectory correction system (EPS) or, the end of a braking action on a fractional Mu-coefficient surface, or the triggering of an airbag or the fact that the steering speed of the rear wheels is greater than a given threshold, or the appearance of a regulation by the anti-lock braking system (ABS) of the motor vehicle.

A more precise set of conditions for storing in the main memory can be determined. The conditions below are given for information only and are not limiting:

Condition 1: appearance of an ESP or ABS control and Δtbuf <15 s and Δtmem> 10 s;

Condition 2: receipt of a brake control end signal on a fractional Mu surface and Δtmem> 10 s; Condition 3: VV> 20 km / h and Br> 1.47s and the flywheel speed is less than 707s for less than two seconds and the Mu-split type control is complete and Δtmem> 10 s;

Condition 4: release of an airbag and Δtbuf <15 s. For example, the recording in the main memory 31 takes place immediately when the condition 1, the condition 2, or the condition 4 is achieved or five seconds after the condition 3 is realized.

The output of the main memory 31 can be coupled to external analysis means via transmission means 36.

These external analysis means have as a first function, from the records in the main memory 31, to check the consistency between the steering wheel angle and the vehicle speed, and the steering setpoint of the rear wheels.

It is recalled for all intents and purposes that the steering setpoint of the rear wheels is the sum of a so-called static setpoint (directly proportional to the steering wheel angle at a time t), a "dynamic" setpoint (dependent on the angles of the flying at time t and four previous samples), and a brake setpoint on a split Mu-coefficient surface calculated by the ESP trajectory correction system.

The main memory contains twice six data sequences of 250 ms. All recorded variables (with a step length of 50 ms) are resampled to 10 ms by linear interpolation.

From these resampled parameters, the aforementioned static setpoint is determined. More precisely, the dead zone and the slope of the static setpoint are determined for each step of 10 ms as a function of the speed of the interpolated motor vehicle. The static setpoint is then reconstituted from the values of the door zone, the slope and the resampled flying angle.

The dynamic reference is determined for each step of 10 ms according to the speed of the re-sampled motor vehicle. More specifically, the dynamic setpoint is reconstituted from the resampled parameters, in particular from the re-sampled flying angle and the speed of the re-sampled motor vehicle. The first five samples of the dynamic setpoint are not reconstructed from the resampled parameters, but only interpolated from the portion of the curve already constructed from the parameters stored in the main memory and resampled.

Finally, the steering setpoint of the rear wheels is reconstituted by making a saturated sum of the static setpoint and the dynamic setpoint and the braking setpoint "Mu-split" calculated by the ESP trajectory correction system and stored in the buffer. The saturation applied at time t depends on the speed of the motor vehicle at this moment.

The aforementioned external analysis means then compare the recorded back angle setpoint with the reconstituted setpoint to check whether their values are coherent.

From the reconstituted rear wheels steering setpoint, it is possible to reconstitute the values of the steering angle of the rear wheels, so as to be able to monitor the consistency between the values of the steering angle of the recorded rear wheels and the values of the rear wheels. steering angle of the reconstructed rear wheels. The rear wheel steering actuator (for a four-wheel-drive motor vehicle) is modeled by a second-order filter associated with speed limitation and pure delay. The response of the actuator varies according to many parameters (resistant forces, supply voltage, dispersion actuators, etc.). It is necessary, in order to judge the coherence of the measurement recorded, to allow a variation of the value of the parameters of the filter and that of the limitation in speed. The typical values of these parameters are: natural frequency 6 Hz, damping 0.75 and speed of the maximum actuator 10 ° / s. Since the filter modeling the actuator is of the second order, reconstitution of the steering of the rear wheels requires using the first two values of the steering as registered as initial condition.

Algorithms for calculating the value of the steering angle of the rear wheels for four-wheel steering vehicles are described in patent applications FR 03 14 929; FR 03 15 264 and FR 04 10 651.

FIG. 3 illustrates a mode of implementation of the operation of the module 20.

First of all, the above-mentioned parameters (first set of parameters) are measured during a step 1000. Then, if the conditions concerning the steering speed of the rear wheels and the speed of the motor vehicle are met ((Br, VV )> l ° / s, 20km / h), 1001 this first set of parameters is stored in the buffer memory.

The parameters stored in the buffer are stored in the main memory when an EV20 event occurs, namely: - triggering a path correction system

(EPS) or, the end of a braking action on a split Mu-coefficient surface, or the triggering of an airbag or - the fact that the steering speed of the rear wheels is greater than a given threshold, or the occurrence of regulation by the anti-lock system of the wheels (ABS) of the motor vehicle.

This mode of implementation takes place when the motor vehicle rolls in nominal mode. A backup can be performed by auxiliary modules as illustrated in the following figures, when the motor vehicle operates in degraded mode.

Referring now to FIG. 4 which more specifically illustrates an embodiment of the module 10, the module 10 manages the situations considered as being limited from the point of view of the operation of the system. For this embodiment, three situations were chosen, namely: the locking of the steering actuator of the four steering wheels, and - waiting for confirmation of a fault, and the stopping of the thermal engine at a speed not -nothing.

A submodule 100 manages the case where the steering actuator is blocked. When the current exceeds 20 A for 2 seconds without any motion being detected by the Hall effect sensors, the steering actuator switches to safe mode for 10 seconds. During this safe mode, the actuator remains energized but no longer tries to control the wheels. After 10 seconds the actuator drives the wheels again. If the current exceeds 20 A again, without any movement being detected by the Hall effect sensors, the system switches to degraded mode. Therefore, an error code is written, the driver is notified.

The diagnostic device is triggered when the actuator enters secure mode.

The sub-module 100 comprises a set of sensors 101 able to measure the temperature of the electronic control unit of the four-wheel-drive vehicle ("ECU" for "Electronic Control Unit", in English), the steering angle rear wheels, the speed of the motor vehicle, the mileage. Sub-module 100 also includes an occurrence counter 102.

The sensors 101 and the occurrence counter 102 are coupled to another memory 103 (auxiliary memory, for example of the E2prom type). This memory 103 comprises two recording areas 104 and 105 so as to record two different situations. The third recorded situation overwrites the first. Each recording area 104 and 105 can record 11 bytes of data.

This recording in the memory 103 takes place when the wheel actuator is blocked, event referenced by EV100, occurs, via a connection

106a.

The module 10 also includes a second sub-module 200. This second submodule 200 manages situations where the motor vehicle is waiting for confirmation of a fault. When the angle of the steering wheel or the speed of the motor vehicle is invalid, or detected as being erroneous by the various monitoring devices set up in the motor vehicle, the latter freezes while waiting for the variable to be valid again or otherwise the error is confirmed (if the error is confirmed, the system goes into degraded mode). The diagnostic device is triggered when the system freezes at an angle greater than 1 ° and at a speed greater than 20 km / h.

The submodule 200 comprises a set of sensors 201 able to measure the voltage of the battery of the motor vehicle, the duration of disability of the aforementioned variable, the state of the indicator of the actuator of the four-wheel steering and mileage. Sub-module 200 also includes an occurrence counter 202.

This occurrence counter 202 and the set of sensors 201 are connected to another memory 203 (auxiliary memory, for example of type E2prom) comprising two recording areas 204 and 205.

The connection between the sensors 201, the occurrence counter 202 and the memory 203 is performed via a connection 206.

Each recording area 204 and 205 can record 14 bytes. The event corresponding to the fault confirmation wait is referenced by EV200. This event EV200 is transmitted via a connection 206a.

Finally, the module 10 includes a third submodule 300 concerning the case where the heat engine stops. Stopping the engine while the steering angle of the rear wheels is greater than 1 ° forms an event referenced EV300.

The submodule 300 comprises a set of sensors 301 able to measure the voltage of the battery of the motor vehicle and the mileage. It also comprises an occurrence counter 302. The submodule 300 comprises a memory (auxiliary memory), for example of the E2prom type, comprising two recording areas 304 and 305.

The sensor assembly 301 and the counter 302 are coupled to the memory 303 via a connection 306.

The parameters measured by the sensors 301 and the counting of the counter 302 are stored in one of the recording areas of the memory 303 when the event EV300 occurs, that is to say when the engine is stopped while the speed of the motor vehicle is not zero and that the steering angle of the rear wheels is greater than 1 °.

Event EV300 is transmitted via a 306a connection. Each recording area 304 and 305 is able to store 9 bytes of data each.

Referring now to FIG. 5, this figure more particularly illustrates the module 40 able to record the parameters testifying to accident situations resulting in the triggering of an airbag. The module 40 comprises a set of sensors 41 able to measure the value of the angle of the steering wheel of the motor vehicle, the steering angle of the rear wheels measured and the speed of the motor vehicle. The module 40 comprises a memory, for example of the Eprom type 43. This comprises two recording areas 44 and 45. The set of sensors 41 is connected to the memory 43 via a connection 46. The recording of the measured data from the sensors 41 in the memory 43 is done when the airbag is triggered, this event being referenced by EV40, and transmitted via a connection 46a.

More precisely, the last ten seconds preceding the activation of the airbag are recorded in the memory 43.

The data recorded by the memory 43 could be transferred to a means of analysis external to the motor vehicle so as to reconstruct the steering setpoint of the four steering wheels. It can therefore be ensured in these cases that the angle of the four guiding wheels measured is consistent with the parameters measured by the sensors 41 during the seconds preceding the triggering of the airbag.

An advantage of the device according to the invention is to finally limit the number of recordings in the main memory and the auxiliary memories because of the criteria chosen to proceed to a recording. Moreover, the proposed device makes it possible to limit itself to a total memory size of E2prom type of 680 bytes.

Claims

1 -Diagnostic device for a posteriori analysis of the behavior of a four-wheeled motor vehicle, comprising a set of sensors able to measure selected parameters representative of the state of the motor vehicle, characterized in that it comprises in addition at least one main memory, a first set of sensors (21,23) capable of measuring a first set of parameters, a buffer memory (25) capable of storing said first set of parameters when the angular speed of turning of the rear wheels and the speed of the motor vehicle respectively exceed a given threshold, the buffer memory being coupled to said main memory via transfer means able to transfer the data from the buffer memory (25) to the main memory (31) when a predetermined event (EV20) occurs while the motor vehicle is operating in nominal mode. 2-Device according to claim 1, wherein said event is representative of the limiting situations from the point of view of the dynamics of the motor vehicle.

3 -Dispositif according to claim 2, wherein said event (EV20) representative of the limit situations from the point of view of the dynamics of the motor vehicle is selected from the triggering of a trajectory correction system, the end of an action of braking on a fractional Mu-coefficient surface and the triggering of an airbag, a steering speed of the rear wheels greater than another given threshold, a regulation action by an anti-lock system of the wheels. 4-Device according to claim 3, wherein the parameters of the first set are selected from the steering wheel angle of the motor vehicle, the speed of the steering wheel of the motor vehicle, the speed of the motor vehicle, the steering angle of the rear wheels of the vehicle the steering setpoint of the rear wheels of the motor vehicle, the steering setpoint for turning the rear wheels of the motor vehicle, the dynamic steering setpoint for the rear wheels of the motor vehicle, the angular setpoint of the rear wheels for braking on a surface with a coefficient of adhesion Mu- fractionated, all of the aforementioned parameters being measured at different times before the storage moment in the buffer memory, and also selected from the mileage of the motor vehicle at the moment of storage and the number of times that a memorization is performed in the buffer.

5. Device according to one of the preceding claims, further comprising transmission means (36) capable of transmitting the data stored in the main memory to external analysis means to the motor vehicle, so that the analysis means reconstitute the steering setpoint at the various storage moments in the buffer memory, to check the consistency of the reconstituted steering setpoint with values of the steering angle and the speed of the motor vehicle taken at these different times.

6. Device according to one of the preceding claims, wherein said event is representative of the limiting situations from the point of view of the operation of the motor vehicle.

7-Device according to one of the preceding claims, further comprising at least one auxiliary memory (103, 203, 303, 43) capable of recording parameters representative of the state of the motor vehicle when a failure occurs and the vehicle automobile operates in degraded mode.

8-diagnostic method for a posteriori analysis of the behavior of a motor vehicle with four steering wheels, said method comprising a step of measuring selected parameters representative of the state of the motor vehicle, the method being characterized by the fact that measurement step comprises a first measurement of a first set of parameters, and in that said measurement step is followed by a step of storing the first set of parameters when the rear wheel steering speed and the speed of the motor vehicle exceed respectively a given threshold and a main step of recording the first set of stored parameters, when a predetermined event occurs while the motor vehicle is operating in nominal mode. The method of claim 8, further comprising an auxiliary step of recording, when a failure occurs and the motor vehicle operates in degraded mode.