method for controlling a motor vehicle in the event of the vehicle beginning to tip over

Abstract

A method for controlling a motor vehicle comprising an AED and an ESP implementing said method, consisting, after detecting (100) a roll angle exceeding a first determined threshold, called the critical threshold, corresponding to the beginning of a rollover, of commanding (200) the AED to apply (300) a first steering torque to the vehicle's steering wheels with a determined steering angle and a determined positive acceleration, in the direction of rollover, then, when the roll angle reaches a second determined threshold, lower than the first threshold, and with a determined negative angular acceleration, of applying (400) a determined counter-steering torque, in a direction opposite to the direction of rollover; the successive steering and counter-steering torques counteracting the rollover force of the vehicle and a resumption of control (500) of the vehicle by the ESP. (Figure 4)

Description

Title of the invention: Method for controlling a motor vehicle in the event of the vehicle beginning to tip over

[0001] The present invention relates generally to the field of active safety of motor vehicles equipped with a steering wheel having an electric power steering system, also designated by the acronym "EPS" for Electric Power Steering and a dynamic control system of the trajectory and stability of the vehicle, also designated by the Anglo-Saxon acronym "ESP" for "Electronic Stability Program", and relates more particularly to a method of controlling a vehicle in the event of the beginning of the vehicle tipping around its roll axis.

[0002] In certain situations in the life of a vehicle, the latter may begin to tilt around its axis of roll when taking a turn at high speed or following a collision with a third vehicle hitting the vehicle from the rear side, or when the driver of the vehicle wants to avoid an obstacle by making a sudden turn of the steering wheel which can cause, at high speed, a swerve with a beginning of the vehicle overturning or even rolling over.

[0003] The methods implemented to avoid a rollover are essentially preventive and corrective by acting on the selective braking of the wheels, the adjustment of the wheel suspension, ... allowing to counter the force tending to make the vehicle leave its trajectory and potentially leading to a rollover of the vehicle, when thresholds of speed, lateral acceleration or yaw angle exceed determined critical thresholds.

[0004] Such methods monitor the dynamic behavior of the vehicle to identify dangerous life situations that could cause the vehicle to roll over. They primarily implement ESP to control speed and maintain vehicle stability.

[0005] However, these methods have their limits and are not always effective, particularly in the face of situations of brutal side collisions resulting in the lifting of both wheels on the same side of the vehicle that suffered the impact.

[0006] The vehicle then becomes momentarily unbalanced, on two wheels (the two wheels aligned on the same side of the vehicle, opposite to the one that was hit) and is therefore liable to tip over and overturn, with potentially serious consequences for the passengers of the vehicle and other road users in the immediate vicinity of the vehicle hit.

[0007] The objective of the present invention is to provide a safety solution to this particularly dangerous "extreme" situation, by acting automatically and abruptly on the steering wheel to counter the tipping force and bring the vehicle back onto its four wheels for the ESP to regain control of the vehicle.

[0008] To this end, the invention has as its first object a method of controlling a motor vehicle comprising an electric power steering system, called EPS, and a trajectory and stability control system, called ESP, implementing said method; said method consisting, after detecting a roll angle greater than a first determined threshold, called the critical threshold, corresponding to the beginning of a tipping of the vehicle, of commanding the EPS to apply a steering torque on the steering wheels of the vehicle with a determined steering angle and a determined positive acceleration, then, when the roll angle reaches a second determined threshold, lower than the first threshold, and with a determined negative angular acceleration, of applying a determined counter-steering torque, in a direction opposite to the direction of tipping;The successive steering and counter-steering pairs allow the vehicle's tipping force to be countered and the ESP to regain control of the vehicle.

[0009] According to one feature, the method consists of comparing the roll angle data obtained by means of determining the roll angle, and if the roll angle is greater than a first threshold corresponding to a determined maximum roll angle, typically 12°, exceeding the capabilities of the ESP to straighten the vehicle, then to automatically send a control signal to a control unit of the AED, so that the latter applies the steering torque of a determined angle, typically 15°, in the direction of tipping, with a positive angular acceleration typically of 5 rad / s2, on the steering column, or directly on the steering wheels in the absence of a steering column.

[0010] According to another feature, the method consists of applying the countersteering torque in the opposite direction to the tipping, when the roll angle has typically become less than 5°.

[0011] The present invention has as its second object a computer program product comprising instructions which, when the program is executed by a computer, lead the latter to implement the steps of the process as described above.

[0012] The present invention has as its third object, a motor vehicle comprising an electric power steering system, called EPS, a trajectory and stability control system, called ESP, and a roll angle estimator or a roll angle sensor enabling the roll angle to be determined; said ESP implementing the method as described above.

[0013] The main advantage of the present invention is that it does not require any additional components beyond those already existing on the vehicle and therefore enhances safety without additional cost.

[0014] Other advantages and features of the present invention will become clearer from the following description, given solely by way of non-limiting example and with reference to the drawings in which:

[0015] [Fig-1] schematically illustrates a first life situation likely to to cause a motor vehicle to begin to tip over;

[0016] [Fig.2] schematically illustrates a second life situation likely to cause the vehicle to begin to tip over;

[0017] [Fig.3] schematically illustrates the implementation of vehicle control by a control method according to the invention from the beginning of the vehicle's tilting until it is righted; and

[0018] [Fig.4] illustrates in the form of a flowchart, the main steps of the control process according to the invention.

[0019] The present invention provides a "last resort" solution when state-of-the-art rollover prevention systems have failed to prevent the vehicle from beginning to roll over, typically when the roll angle has exceeded a maximum, or "critical," threshold, allowing the vehicle to "right itself" (loss of vehicle control). The beginning of a rollover is concretely manifested by the two wheels on the same side of the vehicle lifting off the ground.

[0020] Figures 1 and 2 schematically illustrate respectively two examples of life situation of a motor vehicle VHL confronted with a collision likely to cause a reversal, or tipping, of the VHL vehicle.

[0021] Fig. 1 illustrates a first life situation in which the VHL vehicle hits an obstacle on its right, for example, a central median strip or a curb or low wall, which can have the effect, at high speed, of lifting the front right of the VHL vehicle and causing a beginning of tipping.

[0022] Figure 2 illustrates a second life situation in which the VHL vehicle is struck on its right rear side by a third-party vehicle (VHT) coming from the right.

[0023] In [Fig.3], the implementation of the control method according to the invention applied to a motor vehicle VHL comprising an electric power steering system, or EPS, SDA, and a trajectory control and stabilization system, or ESP, SSV, has been schematically represented.

[0024] The DAE, SDA, considered in the example embodiment and illustrated in the center of [Fig.3], mainly comprises a steering wheel VDD, a steering column CDD, an electric power assist motor MEL, and an electronic control unit UCD, also designated as an ECU (Electronic Control Unit). controlling the assistance torque delivered by the MEL motor; torque which is supplied to the steering wheel VDD to turn the steering wheels RDD, RDG of the vehicle VHL via a steering column CDD mechanically linking the steering wheel VDD to the steering wheels RDD, RDG of the vehicle VHL.

[0025] The ESP, SSV, includes at least one computer (ESP computer) which receives information from numerous sensors installed in the VHL vehicle, to enable it to control the trajectory and stability of the VHL vehicle in real time.

[0026] Among these sensors are:

[0027] - wheel speed sensors, measuring the rotational speed of each of the wheels;

[0028] - a vehicle speed sensor (VHL) which calculates the speed of the vehicle (VHL) in an even more precise way than that displayed on the speedometer;

[0029] - a steering wheel angle sensor, located near the front suspension or in the column CDD steering. It allows the ECU, UCD, to know at all times the steering angle ADB of the steering wheels RDD and RDG;

[0030] - a transverse acceleration sensor, which measures the acceleration acting on the VHL vehicle perpendicular to the direction of travel;

[0031] - a yaw rate sensor, which alerts the ESP when the VHL vehicle reaches a abnormal and dangerous threshold; and

[0032] - a CAR ARV roll angle sensor.

[0033] Only the ARV roll angle CAR sensor is shown in [Fig.3].

[0034] The ARV roll angle can also be estimated or calculated using various methods, including an estimator that uses information from angular velocity and acceleration sensors, the load transfer rate, the AIV tilt angle of the VHL vehicle via an inertial measurement unit,...

[0035] The ESP, SSV, compares the ARV roll angle data obtained by the ARV roll angle determination means (CAR sensor or estimator) and if the ARV roll angle is greater than a threshold corresponding to a determined maximum roll angle "critical", typically 12°, exceeding the capabilities of the ESP, SSV, to right the vehicle, then it automatically sends a control signal to the control unit UCD of the ESD, SDA, so that the latter applies a sudden and rapid steering torque CDB of a determined steering angle ADB, typically 15°, in the direction of rollover, with a positive angular acceleration typically of 5 rad / s2, on the steering column CDD, or directly on the steering wheels RDD, RDG if the vehicle is equipped with "steer-by-wire" type steering,An anglicism used to designate a steering system without a mechanical link (without a steering column) between the steering wheel (VDD) and the steering wheels (RDD, RDG) of the vehicle (VHL).

[0036] The ESP, SSV sends a control signal to the electric power steering system DAE to straighten the steering wheel VDD with a reverse steering torque, or counter-steering torque CCB, determined allowing the ESP, SSV to regain control of the vehicle only when it detects that the roll angle ARV has become less than 5° with a negative angular acceleration.

[0037] This maneuver translates into a sudden turn of the steering wheel in the direction of the roll and then in the opposite direction, allowing the roll force to be countered and the ARV roll angle to be brought back below the "critical" threshold, allowing the ESP, SSV, to regain control of the VHL vehicle.

[0038] The process implemented by the ESP, SSV system can be described synthetically by the steps of the flowchart in [Fig.4].

[0039] The method according to the invention consists, in order to counter the tipping force of the VHL vehicle, after detecting 100 a roll angle ARV greater than a first determined threshold, called the critical threshold, corresponding to a start of tipping of the VHL vehicle, of commanding 200 the electric power steering system SDA of the VHL vehicle so that the latter applies 300 a steering torque CDB on the steering wheels RDD, RDG of the VHL vehicle, with a determined angle ADB and a determined acceleration, in the direction of tipping.

[0040] Then, when the roll angle ARV has reached a second predetermined threshold, lower than the first, with a negative angular acceleration, the method consists of applying a predetermined countersteering torque CCB to the steering wheels RDD, RDG, in a direction opposite to the roll, enabling the ESP, SSV. The successive steering and countersteering torques CDB and CCB counteract the roll force of the vehicle VHL and allow the ESP to regain control of the vehicle VHL.

[0041] The invention also relates to a computer program product comprising instructions which, when the program is executed by a computer, and in particular by the ESP computer, lead the latter to implement the steps of the process as described above.

Claims

Demands

1. Method of controlling a motor vehicle (MV) comprising an electric power steering (EPS) system and a trajectory and stability control (TSC) system, implementing said method; said method consisting, after detecting (100) a roll angle (ARV) greater than a first determined threshold, called the critical threshold, corresponding to the beginning of a tipping of the vehicle (VHL), of commanding (200) the DAE (SDA) to apply (300) a steering torque (CDB) on the steering wheels (RDD, RDG) of the vehicle (VHL) with a determined steering angle (ADB) and a determined positive acceleration, in the direction of tipping of the vehicle (VHL) then, when the roll angle (ARV) reaches a second determined threshold, lower than the first threshold, and with a determined negative angular acceleration, of applying (400) a determined counter-steering torque (CCB), in a direction opposite to the direction of tipping;the successive steering and counter-steering pairs (CDB, CCB) allowing to counter the tipping force of the vehicle (VHL) and a resumption of control (500) of the vehicle (VHL) by the ESP (SSV).;

2. A method according to the preceding claim, consisting of comparing the roll angle data (ARV) obtained by means (CAR) for determining the roll angle (ARV), and if the roll angle (ARV) is greater (100) than a first threshold corresponding to a determined maximum roll angle, typically 12°, exceeding the capabilities of the ESP (SSV) to right the vehicle (VHL), then to automatically send (200) a control signal to a control unit (UCD) of the AED (SDA), so that the latter applies (300) the steering torque (CDB) of a determined angle, typically 15°, in the direction of rollover, with a positive angular acceleration typically of 5 rad / s2, on the steering column (CDD), or directly on the steering wheels (RDD, RGG) in the absence of a steering column (CDD).

3. A method according to any one of the preceding claims, consisting of applying the countersteering torque (CCB) in the opposite direction to the tipping, when the roll angle (ARV) has typically become less than 5°.

4. Product computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the process according to any one of claims 1 to 3.

5. Motor vehicle (MV) comprising an electric power steering system, referred to as EPS (Electric Power Steering), a stability and trajectory control system, referred to as ESP (SVT), and a roll angle estimator (ROI) for determining the roll angle; said ESP (SVT) implementing the method according to any one of claims 1 to 3.

6. Motor vehicle (MV) comprising an electric power steering system, referred to as EPS (Electric Power Steering), a stability and trajectory control system, referred to as ESP (SVT), and a roll angle sensor (ROS) for determining the roll angle; said ESP (SVT) implementing the method according to any one of claims 1 to 3.