Method for guiding a motor vehicle - Patents.com
Patent Information
- Application Number
- JP2024547321
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-09
- Filing Date
- 2023-01-13
- Publication Date
- 2025-02-28
Smart Images
Figure 2025505698000001_ABST
Abstract
Description
Summary of the Invention
[0001] The present invention relates to a method for guiding an automated vehicle. The present invention further relates to a device for guiding an automated vehicle. The present invention also relates to a computer program implementing one of the aforementioned methods. Finally, the present invention relates to a recording medium on which such a program is recorded.
[0002] The lateral guidance of an automated vehicle includes, in particular, the automation of lane-changing maneuvers. Existing control solutions that enable lane-changing maneuvers to be performed generally emphasize the comfort of the maneuver on the rate of convergence towards a target lane. To that end, these solutions are primarily based on automatic lateral control techniques that limit the capabilities of the vehicle's electrically assisted steering system, and in particular the rate of rotation of the vehicle's steering wheel.
[0003] However, when the lateral distance between the vehicle's traffic lane and the vehicle's destination lane is large, limiting the rotation rate of the steering wheel of a motor vehicle can result in lateral guidance failures (such as deviation of the vehicle's path from the calculated path, or even departure from the destination lane).
[0004] A lane change assistance method is known from document US 8855883 (B2) that involves the driver of the vehicle retaining primary control of the steering wheel. In addition to this lane change assistance method not being applied to autonomous vehicles, this assistance method does not optimize the lane change maneuver with respect to the capabilities of the vehicle's electrically assisted steering system and does not allow the duration of the maneuver to be minimized.
[0005] The object of the present invention is to provide a guidance device and method that remedies the above-mentioned drawbacks and improves on the guidance devices and methods known in the prior art. In particular, the present invention makes it possible to provide a device and method that optimizes lane change maneuvers with respect to the capabilities of the power-assisted steering and minimizes the duration of lane change maneuvers, which is simple, reliable and applicable to autonomous vehicles.
[0006] For this purpose, the invention relates to a method for guiding an autonomous vehicle equipped with speed sensors, gyroscopes, geolocating means, a path planning system, a module for controlling lateral movements, a steering system and wheels, the method comprising the steps of: - The steering system limits the absolute value of the yaw rate of the motor vehicle to a maximum yaw rate; - the rate of change in yaw rate is between the minimum and maximum values, - the rate of change in yaw rate is incremented by a set adjustment increment; It concerns the method.
[0007] The method comprises: - a first step of selecting a rate of change in yaw rate; - a second step of maximizing the virtual reference yaw rate as a function of the rate of change in the yaw rate and the maximum yaw rate; - a third step of transmitting the virtual reference yaw rate to a module for controlling the lateral movement; This includes repetition of
[0008] In one embodiment, the method further comprises the steps of: - a fourth step of generating, by a module for controlling lateral movement, a first steering command from the virtual reference yaw rate; a fifth step of transforming, by the steering system, the first steering command into a second steering command consisting of a movement of a steering shaft connected to the steered wheels; Includes.
[0009] The first step is: - a first substep of receiving a first steering command sent by a module for controlling lateral movement in a previous iteration of the method; - a second substep of receiving a second steering command applied by the steering system in the previous iteration of the method; a third substep of calculating a rate of change in the yaw rate as a function of a previous rate of change in the yaw rate calculated in a previous iteration of the method, a minimum value of the rate of change in the yaw rate, a maximum value of the rate of change in the yaw rate, a set adjustment increment and a difference between the first steering command and the second steering command; may include.
[0010] The third sub-step of calculating a rate of change in yaw rate comprises: - comparing the first steering command and the second steering command sent in a previous iteration of the method; - comparing a previous rate of change in yaw rate to a minimum value of the rate of change in yaw rate; may include.
[0011] after that, if the first steering command is different from the second steering command and the previous rate of change in the yaw rate is greater than a minimum value, the rate of change in the yaw rate is equal to the difference between the previous rate of change in the yaw rate and the set adjustment increment; otherwise, if the first steering command is equal to the second steering command and the previous rate of change in the yaw rate is less than the maximum value, the rate of change in the yaw rate is equal to the previous rate of change in the yaw rate plus the set adjustment increment; otherwise, - The rate of change in yaw rate is equal to the previous rate of change in yaw rate.
[0012] In one embodiment, the steering system is capable of processing commands delivered by the module for controlling lateral movement at a frequency less than or equal to a maximum processing frequency, and the step of maximizing the virtual reference yaw rate includes: - modelling a continuous closed-loop system comprising a continuous state model of the motor vehicle and a continuous model of a module for controlling lateral movements; - defining a discretized closed-loop system by discretizing a model of the continuous closed-loop system at a frequency less than or equal to a maximum processing frequency; determining a virtual reference yaw rate by means of an optimization calculation, in particular for maximizing this rate; Includes.
[0013] The invention further relates to a device for guiding an automatic vehicle, the automatic vehicle being equipped with a speed sensor, a gyroscope, a geolocating means, a path planning system, a module for controlling lateral movements, a steering system and a steered wheel, the device comprising hardware and / or software components implementing the method as defined above.
[0014] The invention also relates to a computer program product comprising program code instructions recorded on a computer readable medium, such that, when the program is run on a computer, the steps of the method as defined above are implemented. The invention also relates to a computer program product downloadable from a communications network and / or recorded on a computer readable and / or computer executable data medium, comprising instructions that, when the program is run by a computer, cause the computer to implement the method as defined above.
[0015] The invention further relates to a computer readable data storage medium having recorded thereon a computer program comprising program code instructions for implementing the method as defined above.The invention further relates to a computer readable storage medium comprising instructions which, when executed by a computer, cause the computer to implement the method as defined above.
[0016] The invention further relates to a signal carried on a data medium, carrying a computer program product as defined above.
[0017] The accompanying drawings show, by way of example, an embodiment of a guiding device according to the invention and one mode of execution of the guiding method according to the invention. [Brief description of the drawings]
[0018] [Figure 1] FIG. 1 shows a motor vehicle equipped with a guidance device according to the invention. [Diagram 2] FIG. 2 is a diagram defining the longitudinal and lateral velocities and yaw rate of a motor vehicle. [Diagram 3] 1 is an alternative representation of a motor vehicle equipped with a guidance device according to the present invention; [Figure 4] FIG. 2 illustrates a functional architecture of a guidance device according to the present invention. [Diagram 5] 2 is a flow chart of a guidance method according to the present invention. [Figure 6] FIG. 1 illustrates an algorithm for selecting the rate of change in the yaw rate of a motor vehicle. [Figure 7] FIG. 2 illustrates a first simulation of a fast lane change for a first vehicle not equipped with a guidance device according to the present invention. [Figure 8] FIG. 2 shows a second simulation of a fast lane change of a second vehicle equipped with the first embodiment of the guiding device according to the invention. [Figure 9] FIG. 4 shows a third simulation of a fast lane change for a third vehicle equipped with a second embodiment of a guiding device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] An example of a motor vehicle 100 equipped with an embodiment of a device for guiding a motor vehicle is described below with reference to FIG.
[0020] Autonomous vehicle 100 may be any type of automotive vehicle, including a passenger car, a commercial vehicle, a truck, or even a public transportation vehicle such as a bus or shuttle. In the described embodiment, automotive vehicle 100 is an autonomous vehicle and will be designated an "autonomous vehicle" in the remainder of the description.
[0021] In particular, the automated vehicle may be a non-autonomous vehicle equipped with an advanced driver assistance system, in particular an advanced driver assistance system corresponding to a level higher than or equal to Level 2 automation, i.e., corresponding to partial automation of the vehicle.
[0022] Referring to FIG. 2, one rate and two speeds are next defined that pertain to autonomous vehicle 100 and that will be used in the remainder of this specification.
[0023] An axis called ego-vehicle longitudinal axis 101 is defined as the vehicle's longitudinal axis of symmetry oriented towards the front of the vehicle.
[0024] An axis, called the lateral axis 102 of the ego vehicle, intersects the longitudinal axis 101 at a right angle at a point located at the centre of gravity of the ego vehicle and is oriented towards the left side of the ego vehicle.
[0025] An axis, called ego-vehicle's vertical axis 103, intersects the plane defined by axes 101 and 102 at a right angle at a point located at the ego-vehicle's centre of gravity and is oriented towards the top of the ego-vehicle.
[0026] The ego vehicle's velocity vector 104 projected onto the longitudinal axis 101 defines a longitudinal component 105 of the velocity vector, called the longitudinal velocity.
[0027] The ego vehicle's velocity vector 104 projected onto the lateral axis 102 defines a lateral component 106 of the velocity vector, which is denoted lateral speed, LAT_SPEED, in the remainder of this specification.
[0028] The yaw rate YR of the autonomous vehicle 100 is defined as the rate of rotation of the vehicle about the vertical axis 103 in a counterclockwise direction in the reference frame defined by axes 101 and 102.
[0029] The autonomous vehicle 100 is equipped with a guidance system 70 that controls the steering angle of the vehicle's steered wheels 9 .
[0030] In the remainder of this specification, the term “wheel” is used to designate the steered wheels of autonomous vehicle 100.
[0031] The guidance system 70 mainly comprises the following components: - Speed sensor 1, - Gyroscope 2, - Geolocating system 3 and a path planning module 4, denoted in the remainder of this document as “planning module 4”; a model 5 for estimating the lateral dynamics of the autonomous vehicle 100, denoted in the remainder of this specification as “estimation model 5”; and a module 7 for controlling the lateral movements, denoted in the remainder of this document as "control module 7" or "controller", a steering system 8 including an actuator, in particular an electric actuator; a computing unit 6 comprising a microprocessor 61, a memory 62 and a communication interface 63 enabling the microprocessor 61 to communicate with the planning module 4, the estimation model 5, the control module 7 and the steering system 8; Equipped with.
[0032] Guidance system 70, and the interactions between its components, are described in more detail with reference to FIGS.
[0033] Figure 3 shows three processing layers: a first measuring layer comprising a speed sensor 1, a gyroscope 2 and a geolocating system 3; a second data processing layer comprising a planning module 4 and an estimation model 5; a third layer consisting of a system 10 for controlling lane changes, comprising a microprocessor 6, a control module 7 and a steering system 8; 4 shows the distribution of the components of the guidance system 70 during
[0034] Speed sensor 1 delivers a measurement of the instantaneous speed of autonomous vehicle 100 MES_SPEED, and in particular a measurement of the lateral speed of autonomous vehicle 100 MES_LAT_SPEED.
[0035] Gyroscope 2 enables the instantaneous yaw rate MES_YR of autonomous vehicle 100 to be measured.
[0036] The geo-locating system 3 allows the geographical position POS of the autonomous vehicle 100 on a map to be determined. In one embodiment, the geo-locating system 3 is a GPS.
[0037] The planning module 4 determines a reference path REF_TRAJ of the autonomous vehicle 100 from the instantaneous position POS delivered by the geolocating system 3. The reference path REF_TRAJ is a path used to generate movement commands depending on the current kinematic parameters of the autonomous vehicle 100 and the planned route. Advantageously, the reference path REF_TRAJ is determined in the light of operational and / or tactical decisions made by the autonomous vehicle, such as lane changes or obstacle avoidance. The reference path calculated by the planning module 4 comprises in particular a reference yaw rate REF_YR to be applied to follow the reference path. The module 4 transmits the reference yaw rate REF_YR to the microprocessor 6.
[0038] The estimation model 5 calculates a modeled value of the yaw rate MOD_YR and a modeled value of the lateral speed MOD_LAT_SPEED from the speed measurement(s) MES_SPEED and / or MES_LAT_SPEED and the yaw rate measurement MES_YR delivered by the speed sensor 1 and the gyroscope 2. The modeled value of the yaw rate MOD_YR and the modeled value of the lateral speed MOD_LAT_SPEED are then transmitted to a computing unit 6 comprising a microprocessor 61.
[0039] The microprocessor 61 therefore receives in particular the following data: - a modeled value MOD_YR of the yaw rate of the autonomous vehicle 100; - a modeled value of the lateral speed of the autonomous vehicle 100, MOD_LAT_SPEED; a reference path REF_TRAJ with a reference yaw rate YR_REF; The autonomous vehicle 100 receives data from the planning module 4 and the estimation model 5 regarding a first path of the autonomous vehicle 100 defined by:
[0040] The microprocessor 61 generates a virtual reference path VR_TRAJ and transmits the virtual reference path VR_TRAJ to a module 7 for controlling the lateral movements. The virtual reference path VR_TRAJ comprises, in particular, a virtual reference yaw rate VR_YR.
[0041] In the remainder of this specification, the virtual reference path VR_TRAJ will be denoted as "virtual path VR_TRAJ", and the virtual reference yaw rate VR_YR will be denoted as "virtual yaw rate VR_YR".
[0042] As will be seen in the remainder of this specification, the virtual path VR_TRAJ is a path calculated from a reference path REF_TRAJ delivered by the planning module 4. These two paths are calculated to satisfy different constraints, the reference path REF_TRAJ delivered by the planning module 4 optimizing the comfort of the user of the vehicle and the virtual path VR_TRAJ optimizing the speed of execution of a lane change maneuver.
[0043] As shown in more detail in FIG. 4, to calculate the virtual path VR_TRAJ, the microprocessor 61 - the model of control module 7, CT_MOD; - a steering command STEER_CMD delivered by a first feedback loop B1 from the output of the control module 7; - the applied steering command APP_STEER_CMD, delivered by a second feedback loop B2 from the output of the steering system 8; and Further receive.
[0044] The model CT_MOD of the control module 7 is used in particular in the processing carried out in step E2 of the guidance method according to the invention for optimizing the speed of execution of a lane-changing maneuver.
[0045] The steering command STEER_CMD is determined by the control module 7 from the virtual path VR_TRAJ delivered by the microprocessor 6. The steering command STEER_CMD comprises in particular the rotation angle of the steering wheel of the autonomous vehicle 100.
[0046] The steering command STEER_CMD is then transmitted to the steering system 8. The steering system advantageously comprises an electric power steering system EPS which converts the steering command STEER_CMD into a movement, in particular a rotational movement, of a control shaft which is connected to the wheels 9, for example as a rack. The rotational movement of the control shaft adopted by the electric power steering system EPS is measured. Thus, a measured value APPL_STEER_CMD of the actual applied rotation angle of the steering wheel is obtained at the output of the steering system 8.
[0047] In the described embodiment, the steering command STEER_CMD is equivalent to the rotation angle of the steering wheel, and in particular of the virtual steering wheel. In the described embodiment, the measurement APPL_STEER_CMD is likewise equivalent to the rotation angle of the steering wheel, and in particular of the virtual steering wheel. Alternatively, these quantities may be equivalent to the steering angle of the steered wheel.
[0048] In a preferred embodiment, the steering system 8 limits the absolute value of the yaw rate of the motor vehicle to a maximum yaw rate MAX_YR_ABS.
[0049] Further, in this embodiment of the steering system 8, the rate of change in yaw rate is between a minimum value of the rate of change in yaw rate MIN_SR and a maximum value of the rate of change in yaw rate MAX_SR, and the rate of change in yaw rate is incremented by an adjustment increment SR_STEP.
[0050] In the remainder of this specification, the term "rate of change in yaw rate SEL_SR" or "selected rate of change SEL_SR" or "rate of change SEL_SR" designates the maximum change in absolute value (in radians per second) that the yaw rate can undergo in a step in which the yaw rate changes. As will be seen in the remainder of this specification, the rate of change SEL_SR varies during the implementation of the present invention, which means that the yaw rate of the vehicle increases or decreases relatively quickly during the course of the guidance method according to the present invention. At each iteration of the guidance method, the rate of change SEL_SR is recalculated to define the maximum change in absolute value that the yaw rate can undergo in this iteration of the method.
[0051] In one embodiment, the microprocessor 61 includes the following modules in communication with each other: - a module 610 for activating induction; a module 611 for selecting a rate of change in the yaw rate, which cooperates with the control module 7 and with the steering system 8; a module 612 for maximizing a virtual reference yaw rate, which cooperates with the planning module 4, the estimation model 5 and the control module 7; - a module 613 for transmitting a virtual reference yaw rate transmission, which cooperates with the control module 7; The present invention enables the execution of a software package comprising:
[0052] One mode of implementation of the guidance method is described below with reference to Figure 5. The method may be considered as a method for operating a guidance device, as described above, or a method for operating a vehicle, as described above.
[0053] The method includes iterations of five successive steps: E1, E2, E3, E4, and E5. The Nth iteration of steps E1 to E5 is described below.
[0054] Advantageously, the first iteration (N=1) is preceded by a step E0 of activating guidance to implement a rapid lane change according to the invention.
[0055] In step E0 it is verified whether at least one criterion for activating a fast lane change is fulfilled.
[0056] In one embodiment, the activation of the fast lane change may be transmitted via a message delivered by a decision module of the autonomous vehicle 100 (not described herein).
[0057] An activation step E0 is then followed by a first iteration of step E1.
[0058] In a first step E1, which will be described with reference to FIG. 6, the rate of change in the yaw rate SEL_SR N is selected.
[0059] In the first iteration (N=1) of the method, which corresponds to step SR1 shown in FIG. N is set to the minimum value MIN_SR. The rate of change SEL_SR N The current value of is recorded in memory 62 and then the process proceeds to a second step E2.
[0060] In subsequent iterations (N>1) of the method, the first step E1 is a first steering command STEER_CMD sent by the module 7 for controlling lateral movements in a previous iteration of the method; N-1 a first substep E11 of receiving - the second steering command APP_STEER_CMD applied by the steering system 8 in the previous iteration of the method N-1 and a second substep E12 of receiving - the previous rate of change in yaw rate calculated in the previous iteration of the method (SEL_SR N-1), a minimum value of the rate of change in the yaw rate MIN_SR, a maximum value of the rate of change in the yaw rate MAX_SR, a set adjustment increment SR_STEP, and a first steering command STEER_CMD N-1 and the second steering command APP_STEER_CMD N-1 The rate of change in yaw rate depending on the difference between SEL_SR N a third substep E13 of calculating Includes.
[0061] In one embodiment, the commands STEER_CMD and APP_STEER_CMD are expressed in degrees and correspond to the angle of rotation of the steering wheel of the autonomous vehicle 100.
[0062] First steering command STEER_CMD N-1 and the second steering command APP_STEER_CMD N-1 a minimum value of the rate of change in the yaw rate MIN_SR, a maximum value of the rate of change in the yaw rate MAX_SR, a set increment of the rate of change in the yaw rate SR_STEP, and a first steering command STEER_CMD N-1 and the second steering command APP_STEER_CMD N-1 The rate of change depending on the discrepancy between SEL_SR N Proceed to substep E13, where
[0063] Sub-step E13 will be explained with reference to steps SR2 to SR8 shown in FIG.
[0064] In step SR2, the current value of the rate of change in yaw rate, i.e., the value adopted in the previous iteration, SEL_SR N-1 is retrieved from memory 62.
[0065] Next, the following two conditions: - First command: STEER_CMD N-1The absolute value of is exactly the second command APP_STEER_CMD N-1 is greater than the absolute value of , and - Rate of change in yaw rate SEL_SR N-1 is strictly greater than the minimum rate of change in yaw rate, MIN_SR It is tested whether it is satisfied.
[0066] If these two conditions are met, proceed to step SR3, where the value of the rate of change in the yaw rate is calculated as follows: SEL_SR N =SEL_SR N-1 -SR_STEP is updated by applying Then, the new value of the rate of change SEL_SR N is recorded in the memory 62, and the process proceeds to step E2.
[0067] Otherwise, go to step SR4 and check if the following two conditions are met: - First command: STEER_CMD N-1 The absolute value of is exactly the second command APP_STEER_CMD N-1 is less than the absolute value of , and - Rate of change in yaw rate SEL_SR N-1 is strictly greater than the minimum rate of change in yaw rate, MIN_SR It is tested whether it is satisfied.
[0068] If these two conditions are met, proceed to step SR5, where the value of the rate of change in yaw rate is calculated as follows: SEL_SR N =SEL_SR N-1 -SR_STEP is updated by applying Then, the new value of the rate of change SEL_SR N is recorded in the memory 62, and the process proceeds to step E2.
[0069] Otherwise, go to step SR6 and check if the following two conditions are met: - First command: STEER_CMD N-1 The absolute value of the second command APP_STEER_CMD N-1 is equal to the absolute value of, and - Rate of change in yaw rate SEL_SR N-1 is strictly smaller than the maximum rate of change in yaw rate MAX_SR It is tested whether it is satisfied.
[0070] If these two conditions are met, proceed to step SR7, and the value of the rate of change in the yaw rate is calculated as follows: SEL_SR N =SEL_SR N-1 +SR_STEP is updated by applying Then, the new value of the rate of change SEL_SR N is recorded in the memory 62, and the process proceeds to step E2.
[0071] Otherwise, the process proceeds to step SR8, and the value of the rate of change in the yaw rate is not changed. SEL_SR N =SEL_SR N-1 Then, proceed to step E2.
[0072] In other words, the rate of change in yaw rate SEL_SR N The algorithm for calculating the first steering command STEER_CMD sent in the previous iteration of the method N-1 and the second steering command APP_STEER_CMD N-1 and - Previous rate of change in yaw rate SEL_SR N-1 to the minimum value MIN_SR or maximum value MAX_SR of the rate of change in the yaw rate. Includes.
[0073] First steering command STEER_CMD N-1 is the second steering command APP_STEER_CMD N-1 and the previous rate of change in yaw rate SEL_SR N-1 If is greater than the minimum value MIN_SR, the rate of change in yaw rate SEL_SR N is the previous rate of change in yaw rate SEL_SR N-1 and the configured adjustment increment SR_STEP.
[0074] Otherwise, the first steering command STEER_CMD N-1 is the second steering command APP_STEER_CMD N-1 and the previous rate of change in yaw rate SEL_SR N-1 If is less than the maximum value MAX_SR, the rate of change in yaw rate SEL_SR N is the previous rate of change in yaw rate SEL_SR N-1 and the configured adjustment increment SR_STEP.
[0075] Otherwise, the rate of change in yaw rate SEL_SR N is the previous rate of change in yaw rate SEL_SR N-1 is equal to.
[0076] Thus, in each iteration of the method, in substep E13, it is verified whether the previous command applied by the steering system 8 is different from the one determined by the control module 7 in the previous iteration. If this is the case, the rate of change in the yaw rate SEL_SR N is decreased to slow down the command sent by the control module 7. Otherwise, the rate of change in yaw rate SEL_SR N is increased to more closely approach the maximum capacity MAX_SWC of the steering system 8. NThe increase and decrease of SR_STEP is done at a set increment SR_STEP at each iteration, and taking into account the minimum and maximum tolerance limits MIN_SR and MAX_SR.
[0077] In step E2, the virtual reference yaw rate V_REF_YR N is stored in memory 62; the rate of change in yaw rate SEL_SR N and the maximum yaw rate MAX_YR_ABS.
[0078] In the described embodiment, the virtual reference yaw rate V_REF_YR N is based on an optimization calculation, the objective of which is to determine the virtual reference yaw rate V_REF_YR while taking into account the limitations of the autonomous vehicle 100, i.e. the model 5 for estimating the lateral dynamics of the autonomous vehicle 100, and the constants of the steering system 8. N The aim is to maximize
[0079] The embodiment described herein is based on the Renault Zoe model. This example is provided by way of illustration and is non-limiting.
[0080] The mathematical formulation of the optimization problem to be solved in this embodiment of the invention is described below with respect to equations Math1-Math8.
[0081] Equations Math1-Math4 define a first mathematical model that represents the state of autonomous vehicle 100.
[0082] The equation Math1 corresponds to the spatial state equation for autonomous vehicle 100. [Math1] TIFF2025505698000002.tif17170, where - A, B and C are the spatial state matrices defined by the formula Math4, - u(t) is the steering wheel rotation angle defined by the formula Math3, x(t) is the vehicle state vector defined by the formula Math2.
[0083] The equation Math2 represents the state vector x(t) of the autonomous vehicle 100. [Math2] TIFF2025505698000003.tif15170, where -v y is the lateral speed of the autonomous vehicle 100, also referred to elsewhere in this specification as the “modeled value of the lateral speed MOD_LAT_SPEED”, expressed in meters per second; TIFF2025505698000004.tif5170 The yaw rate of the autonomous vehicle 100, also referred to elsewhere in this specification as the "modeled yaw rate value MOD_YR," which is expressed in degrees per second.
[0084] The equation Math3 represents the rotation angle u(t) of the steering wheel of autonomous vehicle 100. [Math3] u(t)=δ Where: - δ is the steering wheel rotation angle in degrees.
[0085] The equation Math4 represents the state matrices A, B, and C of the autonomous vehicle 100. [Math4] TIFF2025505698000005.tif68170, where -v x is the longitudinal speed of the autonomous vehicle 100, - C f and C r are expressed in Newtons per radian (N / rad) and relate to vehicle dynamics and represent the bending stiffness characteristics of the front and rear of the vehicle, respectively. - L f and L r are the distances measured between the front and rear wheels, respectively, and the center of gravity of the autonomous vehicle 100, expressed in meters (m); - m is the mass of the vehicle in kilograms (kg); -I z is the inertia of the vehicle about a vertical axis passing through the center of gravity of the vehicle, and inertia is expressed in kilograms per second squared (kg / s 2 ) units.
[0086] The equation Math5 further defines a second mathematical model corresponding to the continuous model of the module 7 for controlling the lateral movement. In step E2, the virtual reference yaw rate V_REF YR N The optimization of the yaw rate by calculating is solved by interconnecting the first closed-loop model and the second closed-loop model. [Math5] TIFF2025505698000006.tif14170, where - A C , B C , C C , D C is the state matrix of module 7 for controlling lateral movement, -x c (t) is the state vector of module 7 for controlling lateral movement, e(t) is the yaw rate error provided as input to the module 7 for controlling the lateral movement, i.e. the modeled value of the yaw rate MOD_YR delivered by the model 5 for estimating the lateral dynamics of the vehicle in the previous iteration of the method and the virtual reference yaw rate V_REF_YR delivered by the microprocessor 61; N-1 is the difference between - δ is referred to elsewhere in this specification as "the first steering command STEER_CMD N " is the output of module 7 for controlling lateral movement.
[0087] The continuous state system thus obtained is discretized with a period of 0.01 seconds, corresponding to the frequency with which the steering system 8 is able to process commands.
[0088] The discretized closed-loop system thus obtained takes into account the equations Math6 and Math7. [Math6] x cl (k+1)=A cl x cl (k)+B cl v(k) y cl (k)=C cl x cl (k)+D cl v(k) Where: -x cl is defined by the formula Math7, - A cl , B cl , C cl , D cl is the state matrix of the closed-loop system, v(k) is the virtual reference yaw rate V_REF_YR, -y cl is the output of the closed loop system, i.e. the output of the module 7 for controlling the lateral movement, or in other words the steering command STEER_CMD. [Math7] TIFF2025505698000007.tif14170, where x is the spatial state vector of the autonomous vehicle 100; -x c is the state vector of the module 7 for controlling the lateral movement.
[0089] The variable v(k), also referred to elsewhere in this specification as the “virtual reference yaw rate V_REF_YR,” is defined by determining the largest value of K between 0 and 1 that takes into account the mathematical formula Math8 for any integer i between 1 and N, where N is the prediction horizon. [Math8] max K x cl (k+1+i)=A cl x cl (k+i)+B cl v(k) Excl (k+1)≦D v(k)=v(k-1)+K(r(k)-v(k-1)) |v(k)-v(k-1)|≦D v Where: - i is an index between 1 and N, - k is the discrete time index, - R is the reference yaw rate REF_YR, -D V is defined elsewhere in this specification as "the rate of change in yaw rate SEL_SR N "The rate of change in yaw rate is also called the "rate of change in yaw rate."
[0090] Thus, at the end of the optimization process, a virtual reference yaw rate V_REF_YR is obtained.Then, the process goes to step E3.
[0091] In step E3, the virtual reference yaw rate V_REF_YR obtained is transmitted to the module 7 for controlling the lateral movements, then the process proceeds to step E4.
[0092] In step E4, the module 7 for controlling the lateral movement calculates the steering command STEER_CMD from the virtual reference yaw rate V_REF_YR. N Generate.
[0093] In one embodiment, the module 7 for controlling lateral movement consists of a high-speed controller that minimizes the yaw rate error e(k), which is considered to be an input to its discretized state-space system shown in equation Math9. [Math9] TIFF2025505698000008.tif27170, where -x c is the state vector of module 7 for controlling lateral movement, - A c , B c , C c , Dc is the state matrix of module 7 for controlling lateral movement.
[0094] This embodiment of the lateral control module 7 corresponds to a conventional controller that allows an automatic steering maneuver to be implemented. As an output, the control system outputs at each sampling time (for example every 100th of a second) a steering command STEER_CMD N will be distributed.
[0095] The lateral control module 7 outputs the steering command STEER_CMD N to the steering system 8, and then proceed to step E5.
[0096] In step E5, the steering system 8 advantageously controls the electric power steering system EPS, which in turn controls the steering command STEER_CMD received from the lateral control module 7. N into a rotational movement of a control shaft connected to the wheels 9. Step E5 involves the measurement of the applied command APPL_STEER_CMD, which may be a measurement of the angle of rotation of the control shaft.
[0097] 7 to 9 show implementations of the guidance method according to the invention. The data shown were taken from a simulation simulating the fastest possible automated lane change that can be performed by an automated Renault Zoe.
[0098] The autonomous vehicle is traveling at a longitudinal speed of 10 meters per second in a first traffic lane and must make a rapid lane change to a second traffic lane. The three simulations differ from each other in several criteria.
[0099] The first criterion concerns the presence of the invention in an autonomous vehicle, In a first simulation (FIG. 7), the autonomous vehicle is not equipped with the invention, In the second simulation (FIG. 8) and the third simulation (FIG. 9), the autonomous vehicle is equipped with the invention.
[0100] The second criterion relates to the lateral distance between the first lane and the second lane, In the first two simulations (Figures 7 and 8), the centerline of the first lane and the centerline of the second lane are separated by a lateral distance of 4 meters; In the third simulation, the centerline of the first lane and the centerline of the second lane are separated by a lateral distance of 7 meters.
[0101] The third criterion concerns the maximum turning capability of the steering wheel: - In the second simulation (Figure 8), the maximum steering rotation capacity is 100 degrees, - In the third simulation (Figure 9), the maximum steering rotation capability is 150 degrees.
[0102] The first simulation is described below with reference to FIG. 7. The first simulation involves a first autonomous vehicle not equipped with the present invention. The first vehicle makes a rapid lane change between a first traffic lane and a second traffic lane separated by a lateral distance of four meters. The vehicle is equipped with a high speed controller. The term "high speed controller" refers to the type of controller used in lane keeping applications.
[0103] Graph G11 plots the variation of the lateral movement in meters (on y-axis 110) of the first autonomous vehicle as a function of time. As shown by curve 111, the first vehicle initiates a lane change at a lateral distance of 4 meters from the reference lane and fails to converge to the second lane, located at a y coordinate of 0. Instead, the first vehicle oscillates around the second lane at the start of the maneuver and then becomes unstable.
[0104] Graph G12 contains two curves, - a curve 121 plots the variation of the yaw rate (expressed in radians per second on the y-axis 120) of the first autonomous vehicle as a function of time; A curve 122 plots the reference yaw rate as defined by the planning module.
[0105] Curves 121, 122 show that the first vehicle is not able to take into account the reference yaw rate set point sent by the planning module.
[0106] Graph G13 and graph G14 make it possible to understand why the first vehicle is not able to apply the reference yaw rate sent by the planning module.
[0107] In particular, graph G13 shows the variation of the steering wheel rotation angle (expressed in degrees on the y-axis 130) as a function of time; - curve 131 shows the variation as a function of time of the steering command delivered by the fast controller, Curve 132 shows the variation as a function of time of the steering command applied by the first vehicle, which variation is much slower than that shown by curve 131 .
[0108] The bandwidth of the controller generates high speed steering commands that exceed the steering capability of the steering system.
[0109] Furthermore, graph G14 shows the variation of the rate of change in the reference yaw rate (expressed in radians per second on the y-axis 141) as a function of time. Curve 141 shows an abrupt and discontinuous change at the start of the first vehicle maneuver (t=0 s). A high speed controller cannot implement such a change in yaw rate.
[0110] The second and third simulations show the effect of the guidance method according to the invention. In the implementation of the invention, the controller was able to implement a maximized virtual reference yaw rate while taking into account the limitations of the steering system of the vehicle.
[0111] The second simulation is described below with reference to Figure 8. The second simulation concerns a second autonomous vehicle equipped with the present invention. The second vehicle performs the same maneuver as the first vehicle, i.e., a rapid lane change between a first traffic lane and a second traffic lane separated by a lateral distance of 4 meters.
[0112] Graph G21 plots the variation of the lateral movement in meters of a second autonomous vehicle as a function of time. The second vehicle initiates a lane change at a lateral distance of 4 meters from the reference lane and converges within 3 seconds to the second lane located at a y coordinate of 0. The amplitude of the initial oscillation relative to the target y coordinate (0 meters) is limited to 0.2 meters.
[0113] Graph G22 contains three curves, a curve 220 plots the variation as a function of time of the reference yaw rate as defined by the planning module; - curve 221 plots the variation as a function of time of the virtual reference yaw rate as defined by the guidance method according to the invention; - curve 222 plots the variation as a function of time of the yaw rate implemented by the second autonomous vehicle.
[0114] The closeness of curve 221 and curve 222 indicates that the second vehicle is capable of applying a virtual reference yaw rate. Between t=0 s and t=0.6 s, the absolute value of the virtual reference yaw rate is gradually increased, which allows the second vehicle to apply the yaw rate setpoint, but at t=0 s, the reference yaw rate 220 delivered by the planning module is quite far from the yaw rate implemented by the second vehicle; the virtual reference yaw rate is gradually varied to meet, at t=0.6 seconds, the curve 222 representing the reference yaw rate as defined by the planning module; At t=5 seconds, the yaw rate implemented by the second vehicle converges to the reference yaw rate as defined by the planning module. It is possible to understand that.
[0115] Graph G23 shows the variation of the steering wheel rotation angle over time. - curve 230 represents the lower limit of the steering wheel rotation angle of the second vehicle, i.e. -100 degrees; - curve 231 represents the upper limit of the steering wheel turning angle of the second vehicle, i.e. +100 degrees; - curve 232 shows the variation as a function of time of the steering commands applied by the second vehicle, - Curve 233 shows the variation as a function of time of the steering command delivered by the fast controller.
[0116] The steering commands generated by the high speed controller take into account the steering capabilities of the steering system. The steering commands 232 applied by the first vehicle therefore take into account the steering commands 233 delivered by the controller.
[0117] Furthermore, graph G24 shows the variation of the rate of change in the virtual reference yaw rate as a function of time. Curve 240 shows the gradual variation of the virtual reference yaw rate at the start of the second vehicle maneuver, which allows the controller to follow this variation.
[0118] The third simulation is described below with reference to FIG. 9. The third simulation concerns a third autonomous vehicle equipped with the present invention. The third vehicle performs a maneuver that generates a larger lateral deviation than the first and second simulations because it is a problem of a quick lane change between a first traffic lane and a second traffic lane separated by a lateral distance of 7 meters. The lower and upper limits of the rotation angle of the steering wheel of the third vehicle are -150 degrees and +150 degrees, respectively.
[0119] Graph G31 plots the variation of the lateral movement in meters of the second autonomous vehicle as a function of time. The third vehicle initiates a lane change at a lateral distance of 7 meters from the reference lane and converges within 5 seconds to the second lane located at a y coordinate of 0. The amplitude of the initial oscillation relative to the target y coordinate (0 meters) is limited to 0.2 meters.
[0120] Graph G32 contains three curves, a curve 320 plots the variation as a function of time of the reference yaw rate as defined by the planning module; - curve 321 plots the variation as a function of time of the virtual reference yaw rate as defined by the guidance method according to the invention; - curve 322 plots the variation as a function of time of the yaw rate implemented by the third autonomous vehicle.
[0121] The closeness of curve 321 and curve 322 indicates that the second vehicle can approach the hypothetical reference yaw rate. Between t=0 s and t=0.8 s, the absolute value of the virtual reference yaw rate is gradually increased, which allows the third vehicle to apply the yaw rate setpoint, but at t=0 s, the reference yaw rate 320 delivered by the planning module is quite far from the yaw rate implemented by the second vehicle; the virtual reference yaw rate is gradually varied to meet, at t=0.8 seconds, the curve 322 representing the reference yaw rate as defined by the planning module; At t=5 seconds, the yaw rate implemented by the third vehicle converges to the reference yaw rate as defined by the planning module. It is possible to understand that.
[0122] Graph G33 shows the variation of the steering wheel rotation angle over time. - curve 330 represents the lower limit of the steering wheel rotation angle of the third vehicle, i.e. -150 degrees; - curve 331 represents the upper limit of the steering wheel turning angle of the third vehicle, i.e. +150 degrees; - curve 332 shows the variation as a function of time of the steering commands applied by the third vehicle, - Curve 333 shows the variation as a function of time of the steering command delivered by the fast controller.
[0123] The steering commands generated by the high speed controller take into account the steering capabilities of the steering system. The steering commands 332 applied by the first vehicle therefore take into account the steering commands 333 delivered by the controller.
[0124] Graph G32 and graph G33 also show the effect of the gradual correction of the rate of change in the yaw rate. The absolute value of the virtual reference yaw rate increases and reaches a plateau at about t=0.65 seconds. Between t=0.65 seconds and t=0.8 seconds, the virtual reference yaw rate is constant, as is the rotation angle of the steering wheel of the third vehicle. The vehicle then reaches the maximum capability of the steering system.
[0125] Furthermore, graph G34 shows the variation of the rate of change in the virtual reference yaw rate as a function of time. Curve 340 shows that the rate of change in the yaw rate was reduced for only two short periods (each less than 1 second) at the start of the maneuver.
[0126] As shown by the three simulations presented, the method according to the invention has been tested in a simulator developed by Renault, which uses the driving parameters of an automated Renault Zoe, which allows the performance of the system to be reliably evaluated.
[0127] The results obtained in the simulations show that the guidance method according to the invention provides a solution to one of the main limitations of automatic steering wheel operation, which is to optimize both the vehicle dynamics and the maximum capabilities of the steering wheel in autonomous mode, while still driving safely.
[0128] In particular, the method of induction according to the present invention comprises: - rapid lane change maneuvers, especially between a first lane and a second lane of traffic when the lateral distance between the first lane and the second lane of traffic is large; - Limitation of maximum steering command by the action of the electrically assisted steering; - Utilization of the maximum rotation rate capacity of the steering wheel This allows multiple devices to be managed simultaneously.
[0129] Thus, the guidance method according to the present invention enables an autonomous vehicle to perform rapid lane change maneuvers while maintaining a stable path throughout the maneuver.
Claims
1. A method for guiding an automotive vehicle (100) equipped with a speed sensor (1), a gyroscope (2), a geolocating means (3), a path planning system (4), a module for controlling lateral movements (7), a steering system (8) and wheels (9), comprising: the steering system (8) limits the absolute value of the yaw rate of the motor vehicle to a maximum yaw rate (MAX_YR_ABS), the rate of change in the yaw rate (SR) being between a minimum value (MIN_SR) and a maximum value (MAX_SR), the rate of change in the yaw rate (SR) being incremented by a set adjustment increment (SR_STEP); The method further comprises: - Rate of change in yaw rate (SEL_SR Ｎ ) a first step (E1) of selecting - the rate of change in yaw rate (SEL_SR Ｎ ) and the maximum yaw rate (MAX_YR_ABS) according to the virtual reference yaw rate (V_REF_YR Ｎ ) and a second step (E2) of maximizing - the virtual reference yaw rate (V_REF_YR Ｎ a third step (E3) of transmitting the signal to said module (7) for controlling the lateral movement; The method of claim 1, further comprising repeating the steps of:
2. The method further comprises, following the third step (E3), said virtual reference yaw rate (V_REF_YR) is calculated by said module (7) for controlling the lateral movement; Ｎ a fourth step (E4) of generating a first steering command (STEER_CMD) from a fifth step (E5) of transforming, by said steering system (8), said first steering command (STEER_CMD) into a second steering command (APP_STEER_CMD) consisting of a movement of a steering shaft connected to said wheels (9) to be steered; The method of claim 1 , comprising:
3. The first step (E1) comprises: the first steering command (STEER_CMD) sent by the module (7) for controlling lateral movements in the previous iteration of the method; Ｎ－１ a first substep (E11) of receiving - the second steering command applied by the steering system (8) in the previous iteration of the method (APP_STEER_CMD Ｎ－１ a second substep (E12) of receiving - the previous rate of change in yaw rate calculated in the previous iteration of the method (SEL_SR Ｎ－１ ), the minimum value of the rate of change in yaw rate (MIN_SR), the maximum value of the rate of change in yaw rate (MAX_SR), the set adjustment increment (SR_STEP), and the first steering command (STEER_CMD Ｎ－１ ) and the second steering command (APP_STEER_CMD Ｎ－１ ) and the rate of change in yaw rate (SEL_SR Ｎ a third substep (E13) of calculating The method of claim 1 or 2, comprising:
4. The rate of change in yaw rate (SEL_SR Ｎ said third substep (E13) of calculating the first steering command (STEER_CMD) sent in the previous iteration of the method; Ｎ－１ ) and the second steering command (APP_STEER_CMD Ｎ－１ ) and - the previous rate of change in yaw rate (SEL_SR Ｎ－１ ) to the minimum rate of change in yaw rate (MIN_SR); and said first steering command (STEER_CMD Ｎ－１ ) is the second steering command (APP_STEER_CMD Ｎ－１ ) and the previous rate of change in yaw rate (SEL_SR Ｎ－１ ) is greater than the minimum value (MIN_SR), the rate of change in yaw rate (SEL_SR Ｎ ) is the previous rate of change in yaw rate (SEL_SR Ｎ－１ ) and the set adjustment increment (SR_STEP); otherwise said first steering command (STEER_CMD Ｎ－１ ) is the second steering command (APP_STEER_CMD Ｎ－１ ) and the previous rate of change in yaw rate (SEL_SR Ｎ－１ ) is less than the maximum value (MAX_SR), the rate of change in yaw rate (SEL_SR Ｎ ) is the previous rate of change in yaw rate (SEL_SR Ｎ－１ ) plus the set adjustment increment (SR_STEP); otherwise - the rate of change in yaw rate (SEL_SR Ｎ ) is the previous rate of change in yaw rate (SEL_SR Ｎ－１ ) The guiding method according to claim 3 .
5. The steering system (8) is capable of processing commands delivered by the module (7) for controlling lateral movements at a frequency less than or equal to a maximum processing frequency (F_MAX), and the virtual reference yaw rate (V_REF_YR Ｎ ) maximizing step (E2) modelling a continuous closed loop system (CL_S) comprising a continuous state model of said motor vehicle (100) and a continuous model of said module (7) for controlling lateral movements; defining a discretized closed-loop system (D_CL_S) by discretizing a model of said continuous closed-loop system (CL_S) at a frequency less than or equal to said maximum processing frequency (F_MAX); - the virtual reference yaw rate (V_REF_YR Ｎ ) by optimization calculations aimed at maximizing this rate, The method according to any one of claims 1 to 4, comprising:
6. A device (70) for guiding an automatic vehicle (100), the automatic vehicle being equipped with a speed sensor (1), a gyroscope (2), a geolocating means (3), a path planning system (4), a module for controlling lateral movements (7), a steering system (8) and steered wheels (9), the device (70) comprising hardware and / or software components (1, 2, 3, 4, 5, 6, 7, 8, 9, 61, 62, 63, 610, 611, 612, 613) implementing the method according to any one of claims 1 to 4.
7. A computer program product comprising program code instructions recorded on a computer readable medium, the program implementing the steps of the method according to any one of claims 1 to 5 when the program is run on a computer.
8. A computer readable data storage medium having recorded thereon a computer program comprising program code instructions for implementing the method according to any one of claims 1 to 5 or according to claim 7.
9. A signal from a data medium carrying a computer program product according to claim 7.