Method for controlling a trajectory of a motor vehicle in a traffic lane

Abstract

The invention relates to a method for controlling a trajectory of a motor vehicle in a traffic lane, the method comprising a step (6) of determining an angle (50), referred to as the steering wheel angle, to be given to a steering system of the vehicle in order to follow the lane, the step (6) of determining the steering wheel angle (50) comprising a step (8) of calculating an angle (48), referred to as the guidance angle (48), using first information (52), the method further comprising a step (10) of acquiring second information (54) relating to an orientation of the lane, and a step (12) of defining a limitation rule (56) on the basis of the second information (54), the step (6) of determining the steering wheel angle (50) comprising a step (14) of correcting the guidance angle (48) in the event of non-compliance with the limitation rule (56).

Description

Description Title of the invention: Method for controlling the trajectory of a motor vehicle along a traffic lane

[0001] The invention relates to a method for controlling a trajectory of a motor vehicle along a traffic lane.

[0002] In this field, driving assistance methods are known in which a vehicle steering system is controlled to keep it in the center of the lane using lateral control of its trajectory. For reasons of comfort, this control must be smooth and not give any jerks that could annoy / surprise the driver.

[0003] Lateral control uses different quantities to calculate a steering angle. In certain situations, particularly road markings and / or brightness, the sensors involved in establishing the quantities used in the control may have poor detection, particularly of a curvature of the lane. In this context, steering wheel vibrations / shocks may be perceived, even in a straight line.

[0004] The invention aims to at least partially overcome the above drawbacks and to this end proposes a method for controlling a trajectory of a motor vehicle along a traffic lane, said method comprising a step of determining an angle, called the steering angle, to be given to a steering system of the vehicle to follow said lane, said step of determining the steering angle comprising a step of calculating an angle, called the guidance angle, using first information, said method further comprising a step of acquiring second information, relating to an orientation of said lane, and a step of defining a limitation rule based on said second information, said step of determining the steering angle comprising a step of correcting the guidance angle in the event of non-compliance with said limitation rule.

[0005] By determining and using a limiting rule, the angle used to guide the vehicle takes into account additional information, namely the second information, different from the first information, this not to participate in the calculation of the angle but only to correct it, if necessary, which makes it possible to reduce the risks of vibration of the steering wheel in the event of insufficiently stable or robust first information. In this way, the lateral control offered by the invention will be more comfortable in a straight line and will maintain the same performance when cornering.

[0006] According to various additional characteristics of the invention, which may be taken together or separately and which form as many embodiments of the invention: the step of acquiring the second information is carried out by means of a vehicle positioning system and road mapping, said second information comprises a nature of the lane, said nature of the lane is chosen from a straight lane or a lane with a bend. said limitation rule comprises a variation interval of a speed of evolution of said guidance angle as a function of the nature of the lane, for a straight lane, the variation interval is between 0 and 2° per second, for a lane with a bend, the variation interval is between 0 and 10° per second, said second information comprises a curvature of the lane in front of the vehicle, said limitation rule comprises a variation interval of a speed of evolution of said angle as a function of said curvature,a maximum of said interval is set by a function taking a starting value for zero curvature and evolving linearly up to a maximum value for a threshold curvature and retaining the same maximum value beyond said threshold curvature, said threshold curvature is 2exp-3, said starting value is 2° per second, said maximum value is 10° per second, said method further comprises a step of processing images relating to the lane intended to be followed by the vehicle, said first information comprises at least data relating to the lane intended to be followed by the vehicle, in particular from the image processing step, said data relating to the lane intended to be followed by the vehicle, from the image processing step, comprise a curvature of the lane, the curvature of the lane is determined at a distance in front of the vehicle depending on the speed of the vehicle,said step of calculating the guidance angle comprises a feedback loop regulation delivering an angle value to be taken into account by the steering system to maintain or align the vehicle relative to a center of the track, in a straight line, and / or a reaction loop regulation delivering an angle value to be taken into account by the steering system as a function of the curvature of the track, said step of calculating the guidance angle uses a sum of the angle value obtained by feedback and the angle value obtained by reaction.,

[0007] The invention also relates to an on-board management system in a motor vehicle comprising hardware and / or software elements implementing the control method described above.

[0008] The invention also relates to a motor vehicle comprising said management system.

[0009] The invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the control method described above, when said program operates on a computer.

[0010] The invention also relates to a computer-readable data recording medium on which is recorded a computer program comprising program code instructions for implementing the steps of the control method described above, when said program is running on a computer.

[0011] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the detailed explanatory description which follows, of at least one embodiment of the invention given by way of purely illustrative and non-limiting example, with reference to the appended schematic drawings among which:

[0012] [Fig.l] schematically illustrates a motor vehicle in a configuration for using the method according to the invention;

[0013] [Fig.2] schematically illustrates an example of implementation of the method according to the invention;

[0014] [Fig.3] schematically illustrates a curve indicating, as a function of a curvature of a track, values ​​taken by a maximum of a parameter, used in a limitation rule according to the method in accordance with the invention;

[0015] [Fig.4] schematically illustrates an embodiment of one of the steps of the method of [Fig.l].

[0016] As illustrated in [Fig.l], the invention relates to a method for controlling a trajectory of a motor vehicle 1 along a traffic lane 2. Said method is preferably implemented by a management system on board the motor vehicle, in particular a digital information processing management system comprising microprocessors.

[0017] Preferably, said method aims to keep the vehicle 1 along a central line of the lane 2, said central line being here identified by the illustrated arrow 4. In a straight line, said method will therefore have the function of keeping the vehicle in the same direction. In a bend, as illustrated, said method will on the contrary have the function of allowing the vehicle to follow a curvature of the road. For this, lateral control of the vehicle is carried out.

[0018] More specifically, said method comprising a step of determining an angle, called the steering angle, to be given to a steering system of the vehicle to follow said lane 2. Said angle is, for example, zero if the lane is in a straight line. On the other hand, it takes a given value, non-zero, if the lane turns. We understand the importance of a good determination of such an angle. A false estimate will result in the determination of a steering angle deflecting the vehicle towards the inside of the bend, according to the arrow marked 4', or towards the outside of the bend, according to the arrow marked 4”.

[0019] As illustrated in [Fig.2], said step 6 of determining the steering wheel angle 50 comprises a step 8 of calculating an angle 48, called guidance angle, using first information 52.

[0020] Said first information 52 preferably comprises direct information, that is to say, information linked to operating conditions of the vehicle such as, among others, a longitudinal, lateral and / or yaw speed of the vehicle, a lateral deviation and / or a heading angle of the vehicle relative to the center of the track, an angle and / or a rotation speed of a wheel of the vehicle relative to a vertical axis, a wheelbase of the vehicle, a mass applied to the front and / or rear axle of the vehicle, a pneumatic stiffness of the front and / or rear wheels of the vehicle. Said first information 52 comes from resources, hardware and / or software, embedded in the vehicle. These are, for example, different sensors delivering measurements, intended to be processed by said digital management system for the calculation of said guidance angle.

[0021] Said first information 52 further comprises data relating to the lane intended to be followed by the vehicle. This concerns in particular the curvature of said lane. The latter is advantageously determined at a distance, in front of the vehicle, depending on the speed of the vehicle.

[0022] According to a preferred embodiment of the method according to the invention, said data relating to the track intended to be followed by the vehicle, in particular said curvature, come from a step of processing images relating to said track. Said image processing step is carried out, for example, from images obtained using a camera on board the vehicle.

[0023] Said method further comprises a step 10 of acquiring second information 54, relating to an orientation of said track.

[0024] Said second information 54 is preferably indirect information, that is to say, information originating from resources, hardware and / or software, at least partly external to the vehicle, even if data transmission means, on board the vehicle, are possibly involved to communicate said second information to the vehicle in order to allow their processing according to the method according to the invention, in particular using said management system. digital vehicle.

[0025] Preferably, step 10 of acquiring the second information is carried out by means of a vehicle positioning system, for example by geolocation, and road mapping 20.

[0026] Said method further comprises a step 12 of defining a limitation rule 56 based on said second information. Examples of such a rule 56 will be given later. According to the invention, said limitation rule 56 makes it possible to make the lateral control of the vehicle more reliable by preventing the vehicle from deviating too quickly when this is not relevant.

[0027] For this, said step 6 of determining the steering wheel angle 50 comprises a step 14 of correcting the steering angle in the event of non-compliance with said limitation rule 56. In other words, if the steering angle 48 complies with said rule 56, said steering angle 50 resulting from said calculation step 8 is not modified and the steering wheel angle 50 delivered by the method according to the invention for guiding the vehicle is equal to said steering angle 48. On the other hand, if said steering angle 48 does not comply with said rule 56, said steering angle 48 resulting from said calculation step 8 is modified, according to the requirements of said rule 56, and the steering wheel angle delivered by the method according to the invention for guiding the vehicle is equal to said steering angle 48 thus modified.

[0028] Thanks to the limitation rule 6, the angle 50 used to guide the vehicle takes into account additional information, namely the second information 54, this not to participate in the calculation of the angle but only to correct the result delivered by the corresponding step, if necessary. This makes it possible to reduce vibrations of the steering wheel coming from first information that is insufficiently stable or robust.

[0029] Preferably, said limitation rule 6 gives a maximum value of a speed of variation of the steering wheel angle 50. In such a case, said speed of variation of the steering wheel angle 50 is measured and recorded to be compared with the criteria set by said rule.

[0030] According to a first variant of the method according to the invention, said second information 54 comprises a nature of the lane, for example obtained by means of the road map 20 and from a positioning of the vehicle. Said nature of the lane is chosen, for example, from a straight lane or a lane with a bend. Such a variant advantageously corresponds to the use of low-definition mapping.

[0031] Said limitation rule 6 then includes a variation interval of a speed of evolution of said guidance angle 50 depending on the nature of the track. For a straight track, the variation interval is, for example, between 0 and 2° per second. For a track with a bend, the variation interval is, for example, between 0 and 10° per second.

[0032] In other words, by way of example, if the nature of the track resulting from step 10 of acquiring the second information is a straight track, the limitation rule 6 generated will have the effect of preventing variations in the steering angle 50 greater than 2° per second. In this way, if the guidance angle 48 resulting from the calculation step 8 varies too quickly, the value of the steering angle 50 will not correspond to the value of the guidance angle 48 but to a value allowing this variation limit to be respected. In other words, still by way of example and under the same conditions, if the steering angle 50 in the second preceding a time t is on average 3°, the steering angle to be used at time t will be between 1 and 5°. In this way, if the guidance angle 48 is less than 1°, the steering angle 50 will then be reduced to 1°. If the steering angle 48 is greater than 5°, the steering angle 50 will be reduced to 5°.If the 48 steering angle is between 1° and 5°, the 50 steering angle will be equal to the calculated 48 steering angle.

[0033] According to another variant of the method according to the invention, said second information 54 comprises the curvature of the track in front of the vehicle. This is then not the curvature of the track according to the data of the first information but according to different data, for example obtained by means of the road map 20, provided to be sufficiently detailed, and from the positioning of the vehicle, provided to be sufficiently precise. Such a variant advantageously corresponds to the use of high-definition mapping.

[0034] Said limitation rule then includes an interval of variation of a speed of evolution of said steering wheel angle as a function of said curvature.

[0035] As illustrated in [Fig.3], a maximum of said interval is fixed by a function taking a starting value for zero curvature, evolving linearly up to a maximum value for a threshold curvature and maintaining the same maximum value beyond said threshold curvature. In [Fig.3], the curvatures are illustrated on the abscissa, in meters, and the maximum value of the variation of steering wheel angle is illustrated on the ordinate, in degrees / second.

[0036] The said threshold curvature is 2exp-3, which corresponds to a turn with a radius of approximately 500 meters, the said starting value is 2° per second. The said maximum value is 10° per second.

[0037] As illustrated in [Fig.4], said step 8 of calculating the guidance angle 48 comprises regulation by a feedback loop 22. Said feedback loop 22 delivers an angle value 24 to be taken into account by the steering system to maintain or align the vehicle relative to a center of the track, in a straight line.

[0038] Said feedback loop 22 comprises, for example, a vehicle module 30, equipped with the sensors and / or actuators in question, an observer module 32, using as input measurements 34 supplied by the vehicle module 30 to deliver an output 36, in the form of a state vector, a first calculation module 38, carrying out a subtraction between a reference value 40 and the output 36 of the observer module 32, and an amplification module 43 of a result 42 of said subtraction.

[0039] Said step 8 of the calculation of the guidance angle 48 further comprises, alternatively or in combination, a regulation by feedback loop 26. Said feedback loop 26 delivers an angle value 28 to be taken into account by the method according to the invention as a function of the curvature of the track.

[0040] Said reaction loop 26 comprises, for example, the vehicle module 30 and a reaction module 44 delivering said angle value 28 to be taken into account to take into account the curvature of the track.

[0041] Said calculation step 8 uses a sum of an angle value 24 obtained by feedback and the angle value 28 obtained by reaction to determine said guidance angle 48. Said feedback and reaction loops 24, 26 here comprise for this purpose a second calculation module 46 operating said sum.

Claims

Claims

1. Method for controlling a trajectory of a motor vehicle along a traffic lane (1), said method comprising a step (6) of determining an angle (50), called the steering angle, to be given to a steering system of the vehicle to follow said lane (1), said step (6) of determining the steering angle (50) comprising a step (8) of calculating an angle (48), called the guidance angle, using first information (52), said method further comprising a step (10) of acquiring second information (54), relating to an orientation of said lane (1), and a step (12) of defining a limitation rule (56) based on said second information (54), said step (6) of determining the steering angle (50) comprising a step (14) of correcting the guidance angle (48) in the event of non-compliance with said limitation rule (56).

2. Method according to claim 1 in which the step (10) of acquiring the second information (54) is carried out by means of a vehicle positioning system and a road map (20).

3. Method according to the preceding claim in which said second information (54) comprises a nature of the channel.

4. Method according to the preceding claim in which said nature of the track is chosen from straight track or track with a bend, said limitation rule (56) comprising an interval of variation of a speed of evolution of said guidance angle (50) as a function of the nature of the track.

5. A method according to any one of claims 1 or 2 wherein said second information (54) comprises a curvature of the track ahead of the vehicle.

6. Method according to the preceding claim in which said limiting rule (56) comprises an interval of variation of a speed of evolution of said angle as a function of said curvature.

7. Method according to any one of the preceding claims in which said step (8) of calculating the guidance angle (48) comprises a feedback loop regulation (22) delivering an angle value (36) to be taken into account by the steering system to maintain or align the vehicle with respect to a center of the track, in a straight line, and / or a reaction loop regulation (26) delivering an angle value (28) to be taken into account by the steering system depending on the curvature of the track.

8. Method according to the preceding claim in which said step (8) of calculating the angle of the guidance (48) uses a sum of the angle value (24) obtained by feedback and the angle value (28) obtained by reaction.

9. On-board management system in a motor vehicle comprising hardware and / or software elements implementing the control method according to any one of the preceding claims.

10. Motor vehicle according to the preceding claim comprising said management system.

11. A computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the control method according to any one of claims 1 to 8, when said program is running on a computer.

12. A computer-readable data storage medium on which is recorded a computer program comprising program code instructions for implementing the steps of the control method according to any one of claims 1 to 8.

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