WO2003029063A1

WO2003029063A1 - A method and a system at a vehicle

Info

Publication number: WO2003029063A1
Application number: PCT/SE2002/001789
Authority: WO
Inventors: Peter Engelke; Magnus Staaf; Helene Sjöblom
Original assignee: Scania Cv Ab (Publ)
Priority date: 2001-10-03
Filing date: 2002-10-02
Publication date: 2003-04-10
Also published as: DE10297290T5; SE0103288D0; SE522405C2; SE0103288L

Abstract

The invention relates to a method and an arrangement for a vehicle which incorporates a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where the driver of the vehicle has lost control of the latter. The remedial system comprises a central processing unit (CPU) which is arranged to receive and send signals corresponding to values of system parameters. The system parameters comprise assessment parameters (YA, SA, WR, LA, BP, ET, TP, TR, SP, CG, LD) relevant to assessing the vehicle's stability. The system parameters also comprise action parameters (TS, BP1, BP2, BP3, BP4) which relate to the remedial measure. A multiplicity of values of at least one of the system parameters are sent from the central processing unit (CPU) to an information storage unit (ISU) and are stored in the information storage unit (ISU). This makes it possible in cases where the vehicle has been involved in an incident, e.g. an accident, to reconstruct afterwards the course of events during the incident.

Description

A METHOD AND A SYSTEM AT A VEHICLE

TECHNICAL FIELD

The present invention relates to a method and a device for a vehicle incorporating a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where a driver of the vehicle risks losing or has lost control of the vehicle, according to the preambles of claims 1 and 5 respectively.

BACKGROUND

Many vehicles now on the market are equipped with a remedial system of a type marketed under the name ESP® (Electronic Stability Program). Such a system may be present in both passenger cars and utility vehicles. The system is arranged to receive information relevant to the vehicle's stability from various sensors capable of detecting, for example, the vehicle's rotation about a vertical axis and the steering angle. If the driver of the vehicle risks losing or has lost control of the vehicle, the system can automatically activate certain functions, such as reducing the power mobilised or braking one or more wheels, to rectify the situation.

In many contexts it may be desirable to know what happened in a incident, e.g. an accident, in which the vehicle was involved. It may be particularly desirable to investigate how the vehicle or parts of it behaved and what measures were adopted by the remedial system. It may also be desirable to investigate what measures were adopted by the driver of the vehicle. OBJECT OF THE INVENTION

An object of the present invention is to provide a method and a device for a vehicle incorporating a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where a driver of the vehicle risks losing or has lost control of the vehicle, which method and device make it possible, in cases where the vehicle has been involved in an incident, e.g. an accident, to reconstruct afterwards at least partly the course of events during the incident.

BRIEF DESCRIPTION OF THE INVENTION

The aforesaid object is achieved with a method and a device for a vehicle incorporating a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where a driver of the vehicle risks losing or has lost control of the vehicle, according to the preambles of claims 1 and 5 respectively.

Storing values of system parameters, i.e. parameters relevant to the functioning of the remedial system, makes these values available for automatic or manual evaluation at a time subsequent to that of their occurrence in the system. The values of such system parameters may comprise information going into, coming from and calculated in the central processing unit.

The values of system parameters may also comprise information which is not accessed by the remedial system but nevertheless indirectly affects the latter' s operation because it relates to the vehicle's functions or behaviour. Such information may concern certain driver manoeuvres such as activation of the vehicle's wheel brakes via a footbrake control. Alternatively, such information may also be sent to the remedial system to provide a basis for assessing the vehicle's situation and determining one or more appropriate remedial measures.

The system parameters stored in the information storage unit preferably comprise a vertical centre of gravity position for a vehicle load. Alternatively they comprise a vertical centre of gravity position for the vehicle with load. Storing information about the position of the centre of gravity makes it possible to determine whether it was so high as to cause danger during movement of the vehicle.

The system parameters stored in the information storage unit preferably comprise information indicating the extent to which the remedial system is connected or disconnected. This makes it possible to determine afterwards whether the system was disconnected at the time of an accident or other incident and, if such was the case, to establish that no corrective or remedial measures were adopted by the remedial system. This makes it easier in such cases to counter speculation as to whether action by the remedial system was a cause of the incident.

DESCRIPTION OF DRAWING

The invention will now be described in more detail with reference to the accompanying drawing, in which Fig. 1 depicts a block diagram of a system incorporating a device according to a preferred embodiment of the invention. DETAILED DESCRIPTION

To illustrate an embodiment of the invention, it is assumed here that there is in a vehicle a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where a driver of the vehicle risks losing or has lost control of the vehicle. The remedial system may be of a type marketed under the name ESP® (Electronic Stability Program). Reference is made here to Fig. 1. The remedial system incorporates a central processing unit CPU which is arranged to receive and send signals which correspond to values of certain system parameters.

The system parameters comprise assessment parameters relevant to assessing the vehicle's stability, and the central processing unit CPU is arranged to receive or calculate values of the assessment parameters.

The assessment parameters may comprise the vehicle's rotational velocity about its vertical axis YR, steering deflection angle S A, rotation speed of the vehicle's wheels WR, the vehicle's lateral acceleration LA and brake pressure BP. The assessment parameters may also comprise engine torque ET, power control position TP and gear ratio TR.

According to the state of the art, the vehicle's rotational velocity about its vertical axis or yaw angle velocity YR is obtained from a yaw sensor YRS. The steering deflection angle SA can be obtained from a steering deflection sensor SAS, the wheel rotation speed WR can be obtained from wheel rotation speed sensors WRS, lateral acceleration LA can be obtained from a lateral acceleration sensor LAS, brake pressure BP can be obtained from a brake pressure sensor BPS, power control position TP can be obtained from a power control position sensor TPS and gear ratio TR can be obtained from gear ratio sensor TRS. According to the state of the art, the engine torque ET can be calculated by means of an algorithm.

Also according to the state of the art, the central processing unit CPU can obtain or calculate values of parameters corresponding to load weight LD and vertical centre of gravity position CG for the load. For example, according to the state of the art it is possible on vehicles with air suspension to calculate the load weight LD on the basis of signals corresponding to suspension pressure SP from a number of pressure detectors SPS in the vehicle's air suspension system and to the vehicle's total weight TW, the latter calculated on the basis of the engine torque

ET and the wheel rotation speed WR. The vertical centre of gravity position for the load CG can be calculated on the basis of the vehicle's angle of slope on bends, determined by means of the pressure detectors SPS in the vehicle's air suspension system, and the lateral acceleration LA. The central processing unit CPU can also obtain or calculate values of a parameter corresponding to the vertical centre of gravity position CG for the vehicle including the latter' s load LD.

According to the state of the art, the central processing unit CPU uses values of the assessment parameters to derive information about the vehicle's status during operation. The central processing unit CPU compares the vehicle's status with a preprogrammed ideal value and initiates one or more remedial measures to bring the vehicle back to a desired state if the status deviates from the ideal values.

The system parameters also comprise action parameters. The expression "action parameter" means here a parameter which relates to any of the remedial measures which the remedial system is arranged to instigate. An action parameter may be a power mobilisation TS of the vehicle's engine EN. An action parameter may also be a brake pressure BPl, BP2, BP3, BP4 on a particular wheel brake. The central processing unit can be arranged to control individually the vehicle's wheel brakes WBl, WB2, WB3, WB4. A simple example which may be mentioned is a situation in which the vehicle oversteers at a bend so that its rear portion swings outwards at the bend. The oversteering may be established by the central processing unit CPU on the basis of the yaw angle velocity YR and the steering deflection angle SA. A first remedial measure to prevent skidding may be to reduce the engine power mobilised. A signal corresponding to a value of the power mobilised TS is sent from the central processing unit

CPU to the engine EN in order to reduce same. A subsequent measure may be controlled activation of the brake on the outer front wheel. To this end a signal corresponding to a value of the brake pressure is sent from the central processing unit CPU to the wheel brake.

According to the invention, an information storage unit ISU is arranged to obtain from the central processing unit CPU the value of at least one of the assessment parameters and/or the value of at least one action parameter.

The information storage unit ISU is also arranged to store, in a data storage memory, values of assessment parameters and/or action parameters received from the central processing unit CPU. These values are preferably stored in parallel for certain storage periods so that time- correlated values are obtained for each parameter. Storage periods are initiated so that the demands on data storage size are kept low. Storage periods and the data memory must be adapted simultaneously so as to ensure availability of the values of selected parameters when a need for assessment arises. A storage period may extend from a time when the vehicle starts to move from a standstill position to when the vehicle again assumes a standstill position. When the vehicle thereafter begins to move, a new storage period may commence. One possibility is that when a new storage period commences, the values stored in the memory during the preceding storage period during which the vehicle was in motion are deleted. The demand for memory capacity can thus be kept down. Alternatively, values from each successive storage period may be saved to increase the availability of information.

In certain cases the vehicle may be provided with a facility for the driver to switch off the remedial system. The system parameters may comprise information which indicates the extent to which the remedial system is engaged or disengaged. This information may also be stored in the information storage unit ISU.

Further examples of system parameters which may be stored in the information storage unit ISU are the vehicle speed and the outside temperature. In such cases the vehicle speed is not calculated by means of the wheel rotation speed. This makes it possible to compare vehicle speed and wheel rotation speed to see whether one or more of the wheels was locked at the time of an incident or did in some other way have a reduced grip on the road. The outside temperature may give an indication of the extent to which there was a risk of slipperiness at the time of an incident in which the vehicle was involved.

Further system parameters which may be stored in the information storage unit ISU are signals from driver controls which are not accessed by the remedial system. These parameters may assume values which indicate, for example, brake pressure via the foot brake control and the position of the clutch in the vehicle's transmission. The values of these parameters may provide further information which may be valuable in assessing an incident in which the vehicle was involved.

The information storage unit ISU may be arranged to store values of any appropriate system parameters desired. The parameters deemed to be of great significance for assessing the course of events in an incident in which the vehicle is involved are preferably selected for storage. A limitation of the number of system parameters for which values are stored may be applied in the light of practical limitations on storage capacity.

Claims

1. A method for a vehicle incorporating a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where a driver of the vehicle risks losing or has lost control of the vehicle, which remedial system comprises a central processing unit (CPU) arranged to receive and send signals corresponding to values of at least two out of a number of system parameters which comprise at least one assessment parameter (YR, SA, WR, LA, BP, ET, TP, TR, SP,

CG, LD) which is relevant to assessing the vehicle's stability, which central processing unit (CPU) is arranged to receive or calculate a value of the assessment parameter, in addition to which the system parameters also comprise at least one action parameter (TS, BPl, BP2, BP3, BP4) which relates to at least one remedial measure, characterised in that it comprises the steps of sending from the central processing unit (CPU) to an information storage unit (ISU) a multiplicity of values of at least one of the system parameters and storing in the information storage unit (ISU) the values of at least one system parameter which are received from the central processing unit (CPU).

2. A method according to claim 1, whereby the at least one system parameter stored in the information storage unit (ISU) comprises a vertical centre of gravity position (CG) for a load (LD) on the vehicle.

3. A method according to claim 1, whereby the at least one system parameter stored in the information storage unit (ISU) comprises a vertical centre of gravity position (CG) for the vehicle with a load (LD).

4. A method according to any one of the foregoing claims, whereby the at least one system parameter stored in the information storage unit (ISU) comprises information which indicates the extent to which the remedial system is connected or disconnected.

5. An arrangement for a vehicle incorporating a remedial system which is arranged to execute while the vehicle is in motion at least one remedial measure in a situation where a driver of the vehicle risks losing or has lost control of the vehicle, which remedial system comprises a central processing unit (CPU) arranged to receive and send signals corresponding to values of at least two out of a number of system parameters which comprise at least one assessment parameter (YR, S A, WR, LA, BP, ET, TP, TR, SP, CG, LD) which is relevant to assessing of the vehicle's stability, which central processing unit (CPU) is arranged to receive or calculate a value of the assessment parameter, in addition to which the system parameters also comprise at least one action parameter (TS, BPl, BP2, BP3, BP4) which relates to at least one remedial measure, characterised in that it comprises an information storage unit (ISU), and the central processing unit (CPU) is arranged to send a multiplicity of values of at least one of the system parameters to the information storage unit (ISU), and the information storage unit (ISU) is arranged to store the values of at least one system parameter which are received from the central processing unit (CPU).

6. An arrangement according to claim 5, whereby the at least one system parameter which the information storage unit (ISU) is arranged to store comprises a vertical centre of gravity position (CG) for a load (LD) on the vehicle.

7. An arrangement according to claim 5, whereby the at least one system parameter which the information storage unit (ISU) is arranged to store comprises a vertical centre of gravity position (CG) for the vehicle with a load (LD).

8. An arrangement according to any one of claims 5-7, whereby the at least one system parameter which the information storage unit (ISU) is arranged to store comprises information which indicates the extent to which the remedial system is connected or disconnected.