FR2924053A1 - Semi-active anti-rolling system activation or deactivation controlling method for motor vehicle i.e. four-wheel vehicle, involves activating/deactivating system when acceleration value is higher/lower than threshold value, respectively - Google Patents

Abstract

The method involves calculating a value of a transversal acceleration subjected by a motor vehicle in a turn using a specific relationship comprising parameters such as longitudinal speed and radius of curvature of the turn. A semi-active anti-rolling system in upstream of the turn is activated or deactivated when the calculated transversal acceleration value of the vehicle is higher or lower than a threshold transversal acceleration value, respectively. An independent claim is also included for a semi-active anti-rolling system activation/deactivation controlling device comprising a transversal acceleration calculating unit.

Description

METHOD FOR CONTROLLING THE ACTIVATION / DEACTIVATION OF ANTIROULIS SYSTEM FOR A MOTOR VEHICLE AND CORRESPONDING DEVICE The present invention relates to the field of controlling the activation / deactivation of an anti-roll system for a motor vehicle, in particular so-called semi-active anti-roll systems. A semi-active anti-roll system for a motor vehicle conventionally comprises a set of two anti-roll stabilizer half-bars, hereinafter referred to as "bars", capable of being connected to a train of the vehicle, the front axle and / or the rear axle being able to be equipped such bars. The system also includes actuators configured to mate / decouple the control rods from a computer-generated signal (ECU). Advantageously, these actuators do not require a circuit (pump, pipe) hydraulic. When coupled, the bars allow to play on the anti-roll stiffness of the suspension train (s). Conventionally, the bars are decoupled when the vehicle is in a straight line, in which case their stiffness does not decrease comfort, and coupled cornering, which significantly increases the stiffness of suspensions and significantly reduces the roll angle. Also more specifically, according to a first of its objects, the invention relates to a method for controlling the activation / deactivation of an anti-roll system for a motor vehicle comprising the steps of: activating and deactivating the anti-roll system when the transverse acceleration of the vehicle is respectively greater than and less than a threshold transverse acceleration value. Conventionally, such systems require the vehicle to be equipped with at least one transverse acceleration sensor, or even a corner sensor of the vehicle. In addition, given the time required to process the information from the sensors, and the implementation time of the actuators, the vehicle is already in a corner when the roll correction is performed. The present invention aims to overcome these disadvantages by providing a solution to anticipate a turn.

With this objective in view, the device according to the invention, furthermore in accordance with the preamble cited above, is essentially characterized in that it further comprises a step consisting in: calculating the transverse acceleration of the vehicle that will undergo the vehicle in a next turn, - the activation and deactivation of the antiroll system, upstream of said (chord point of the) next turn, being implemented as a function of said calculated transverse acceleration.

Thanks to this characteristic, the anti-roll system can be predisposed in active position (coupled actuators) before a turn and thus reduce the roll of the vehicle into the turn, which increases the comfort of the occupant (s).

In one embodiment, the calculation of the transverse acceleration of the vehicle that the vehicle will undergo in a next turn comprises the steps of: determining the radius of curvature of said next turn from a map, and determining the longitudinal velocity of the vehicle, the transverse acceleration that will undergo the vehicle in the next turn being calculated according to the equation: Gt = Vl '/ R, with Gt the transverse acceleration, Vl the longitudinal speed of the vehicle and R the radius of curvature of the next turn. Preferably, the method according to the invention further comprises the steps of: - determining, from a map, the position of the vehicle and the position of said next turn, and deduce the distance D at said next turn, - calculate the time of reaching Ta of the position of said next turn according to the equation Ta = D / Vl, and activating the antiroll system if the reaching time Ta is less than the value of a threshold time Ts. Preferably, at least one of the magnitudes: radius of curvature of said next turn, position of said next turn, longitudinal speed of the vehicle, position of the vehicle, is determined by GPS positioning means (Global Positioning System). In one embodiment, the method of the invention further comprises a step of: calculating a predictive route of the vehicle trajectory.

Advantageously, the predictive route is determined using the GPS positioning means and the mapping, by automatic vehicle guidance functions.

According to another of its objects, the invention relates to a device for controlling the activation / deactivation of an anti-roll system for a motor vehicle, capable of implementing the method according to the invention, and comprising: - means for activating and deactivating the antiroll system when the transverse acceleration of the vehicle is respectively greater than and less than a threshold transverse acceleration value. The device according to the invention is essentially characterized in that it further comprises: means for calculating the transverse acceleration of the vehicle which the vehicle will undergo in a future turn, the activation and the deactivation of the antiroll system, in upstream of said next turn, 20 being implemented according to said calculated transverse acceleration. Preferably, the device according to the invention further comprises: a map and means for determining the radius of curvature R of said next turn from the map, and means for determining the longitudinal speed of the vehicle. means for calculating the time of reaching (Ta) the position of said next turn according to the equation Ta = D / Vl, and means for activating the anti-roll system if the reaching time is less than the value of a threshold time (Ts). In one embodiment, the device according to the invention further comprises: means for determining the position of the vehicle, the position of said next turn, and the distance (D) at said next turn; means for calculating the reaching time (Ta) 10 of the position of said next turn, and - means for comparing whether the reaching time (Ta) is less than the value of a threshold time (Ts). In this context, the anti-roll system is activated if, in addition, the reaching time (Ta) is less than the value of a threshold time (Ts). In one embodiment, the device according to the invention further comprises positioning means (GPS) configured to determine at least one of the magnitudes: radius of curvature of said next turn, position of said next turn, longitudinal speed. of the vehicle, position of the vehicle. Advantageously, the device according to the invention further comprises means for calculating a predictive route of the trajectory of the vehicle, preferably using positioning means (GPS) and cartography. Finally, the invention also relates to a motor vehicle equipped with the device according to the invention. Other features and advantages of the present invention will emerge more clearly on reading the following description given by way of illustrative and nonlimiting example and with reference to the appended figures in which: FIG. 1 is a block diagram of the invention, and - Figure 2 illustrates an embodiment of the device according to the invention. An object of the present invention is to activate a motor vehicle anti-roll system upstream of a turn, that is to say at the latest at the rope point of said next turn. For this purpose, a step of the method according to the invention consists in calculating the transverse acceleration of the vehicle that will undergo the vehicle in a next turn.

This predictive calculation makes it possible to activate the anti-roll system upstream of said next turn, whereas the measurement of the transverse acceleration according to the prior art only makes it possible to observe that the vehicle is in a turn.

The invention advantageously exploits the data coming from positioning means, preferably satellite, and in this case a Global Positioning System (GPS) sensor, coupled to a geographical map, as shown in a block diagram in FIG. a GPS sensor is analyzed and coupled to a geographical map by analysis means in the form of a model stored preferably in the ECU of the vehicle. The model further includes various decision parameters for controlling the activation / deactivation of the anti-roll system, as seen later.

In one embodiment, measurements made as in the prior art, in particular transverse acceleration, can also be integrated at the input of the model.

Thanks to the data from the positioning means (GPS), the vehicle can be located, located on the geographical map. The direction and direction of movement of the vehicle may also be determined by the positioning means (GPS). The position of the vehicle being known, it is easy thanks to the mapping to calculate the distance D separating the vehicle from a next turn. Preferably, the invention selects for this purpose the next turn 15 on the path of the vehicle. The distance to the next turn can be determined for example by the coordinates of the point of entry of the turn or those of its point of rope. In case of multiple possibilities of directions 20 (roundabout, crow's feet, crossings, etc.), it is possible for example by default to activate the anti-roll system, and decide to disable the anti-roll system for example by measurements. For this purpose, it is possible, for example, to carry out GPS trajectory measurements and deactivate the anti-roll system if it is linear. Measurements of transverse acceleration can also be made and the anti-roll system can be deactivated if it is below a threshold value, or longitudinal velocity measurements, and the anti-roll system can be deactivated if it does not decrease beyond for a while, etc.

In another embodiment, it is also possible to couple the activation of the anti-roll system, moreover, to the selection by the driver of the vehicle of direction indicator means, more commonly known as "turn signals". As a function of the longitudinal velocity Vl, determined for example also by means of the GPS positioning means, and the distance D at the next calculated turn, the time of attaining Ta of said next turn is deduced according to the equation Ta = D / Vl. Thanks to the cartography, we also determine the radius R of the next turn. From these data, the model can calculate the transverse acceleration Gt that the vehicle will undergo in the next turn according to the equation Gt = Vl '/ R. In one embodiment, a set of threshold values, in particular a threshold time Ts and a transverse acceleration threshold Gs, is stored in a memory as decision parameter values for controlling the activation / deactivation of the antiroll system. In one embodiment, an anti-roll system activation strategy stored in the model is to activate said anti-roll system if Ta <Ts and Gt> Gs, i.e., the Ta hit time of the next turn is less than the threshold time Ts, and if the transverse acceleration Gt that will undergo the vehicle in the next turn is greater than the transverse acceleration threshold Gs.

With reference to FIG. 2, the device according to the invention comprises an antiroll system for a motor vehicle 1. The vehicle 1 is equipped with means for activating and deactivating the antiroll system 10 to 13, in this case for a four-wheeled vehicle. wheels, a set of four actuators each of which is capable of coupling / uncoupling an antiroll bar to a respective wheel.

Preferably, the vehicle 1 comprises two anti-roll bars 14, 15, in this case one at the front axle and the other at the rear axle, each antiroll bar connecting the two front wheels or the two rear wheels. When a bar undergoes excessive travel the corresponding actuator 10-13 tends to bring the two wheels to the same height, relying on the box, which rectifies it and reduces roll. When the vehicle 1 is equipped with four anti-roll actuators, four particular typings can for example be envisaged: if the calculated transverse acceleration Gt is greater than a second threshold value Gs2 (Gs2> Gs), it is possible to decide on a typing said understeer in which the stability of the vehicle is preferred to its agility. For this purpose, only the front anti-roll bars are coupled, - on the other hand, if the transverse acceleration remains low and acceptable, that is to say Gs <Gt <Gs2, it is possible to decide on a so-called overstrain typing in which we favor the agility of the vehicle. For this purpose, only the rear anti-roll bars are coupled, - it is also possible to couple the front and rear bars, or - not to couple any of the bars (Gt <Gs). Furthermore, it is still possible to couple the measurement or the estimation of the steering angle e as a decision parameter for controlling the activation / deactivation of the anti-roll system. For example, a reference threshold angle e (preferably dependent on the radius of curvature R of the next turn) is stored in a memory. The flying angle e is estimated or measured, and as a function of at least the difference between the flying angle e and the reference threshold angle es, and preferably also depending on at least one of the elements following: distance to the next turn, longitudinal speed, transverse acceleration, it is decided to control the activation / deactivation of the anti-roll system. The steering speed of the steering wheel of / dt can also be used as a decision parameter.

Claims (10)

A method of controlling the activation / deactivation of an anti-roll system for a motor vehicle comprising the steps of: -activating and deactivating the anti-roll system when the transverse acceleration of the vehicle is respectively greater than and less than an acceleration value transverse threshold, characterized in that it further comprises a step of: - calculating the transverse acceleration (Gt) of the vehicle that will undergo the vehicle in a next turn, -the activation and deactivation of the anti-roll system, in upstream of said next turn, being implemented as a function of said calculated transverse acceleration (Gt). The method of claim 1, further comprising the steps of: - determining the radius of curvature (R) of said next turn, and - determining the longitudinal velocity (Vl) of the vehicle, the transverse acceleration (Gt ) what will the vehicle undergo in the next turn being calculated according to the equation: Gt = Vl '/ R. The method of claim 2, further comprising the steps of: determining, from a map, the position of the vehicle and the position of said next going, and deriving the distance (D) from said next turn calculating the time of reaching (Ta) the position of said next turn according to the equation Ta = D / Vl, and activating the antiroll system if the reaching time (Ta) is less than the value of a time threshold (Ts). 4. Method according to any one of claims 2 or 3, wherein at least one of the variables: radius of curvature of said next turn, position of said next turn, longitudinal speed of the vehicle, vehicle position, is determined by positioning means (GPS). The method of claim 4, further comprising a step of: calculating a predictive route of the vehicle trajectory. 6. A device for controlling the activation / deactivation of an anti-roll system for a motor vehicle, capable of implementing the method according to any one of the preceding claims and comprising: means for activating and deactivating the anti-roll system when the transverse acceleration of the vehicle is respectively greater than and less than a threshold transverse acceleration value, characterized in that it further comprises: means for calculating the transverse acceleration (Gt) of the vehicle which the vehicle will undergo 30 in a next turn, - the activation and deactivation of the anti-roll system, upstream of said next turn, being implemented as a function of said calculated transverse acceleration (Gt). 7. Device according to claim 6, further comprising: - mapping and means for determining the radius of curvature (R) of said next turn from the map, - means for determining the longitudinal speed (Vl) of the vehicle, means for calculating the reaching time (Ta) of the position of said next turn according to the equation Ta = D / Vl, and - means for activating the anti-roll system if the reaching time is less than the value a threshold time (Ts). 8. Device according to claim 7, further comprising: - means for determining the position of the vehicle, the position of said next turn, and the distance (D) at said next turn, - means for calculating the time of reaching (Ta) of the position of said next turn, and - means for comparing whether the reaching time (Ta) is less than the value of a threshold time (Ts). 9. Device according to any one of claims 7 or 8, further comprising positioning means (GPS) configured to determine at least one of the variables: radius of curvature of said next turn, position of said next turn, longitudinal speed. of the vehicle, position of the vehicle. 10. Device according to claim 9, further comprising means for calculating a predictive route of the vehicle trajectory.