Method and device for managing the operation of a driver assistance system for a motor vehicle based on the estimated mass of the vehicle

Abstract

The invention relates to a method for managing the operation of a driver assistance system (10) of a motor vehicle (1) that controls at least one chassis actuator (20) of the vehicle. The invention also relates to a device (100) implementing such a method, as well as a motor vehicle comprising such a device. Figure for the abstract: 1

Description

Title of the invention: Method and device for managing the operation of a driver assistance system for a motor vehicle based on the estimated mass of the vehicle Technical field of the invention

[0001] The present invention relates to the field of driver assistance systems for motor vehicles. The invention relates in particular to a method for managing, by means of a computer device installed in a motor vehicle, the operation of a driver assistance system that controls at least one chassis actuator of the vehicle. The invention also relates to a device implementing such a method. The invention is applicable to motor vehicles such as motor vehicles, in particular cars. Prior art

[0002] It is known that some modern motor vehicles are equipped with a driver assistance system capable of controlling one or more chassis actuators of the vehicle, for example, ESP, which is capable of controlling both the operation of the braking system and the powertrain of a vehicle. Generally, these systems operate using a number of pre-established control laws, with the aim of improving vehicle safety and comfort. However, some of these control laws are defined according to the mass of the vehicle, and a value for the vehicle mass is thus defined at the time of the design of the driver assistance system and then remains constant. However, the mass of a vehicle is not constant because it depends in particular on the vehicle's load.In fact, control laws based on a fixed value for the vehicle's mass, regardless of the vehicle's load, will inevitably lead to inappropriate commands being sent to the chassis actuators, and this will invariably compromise vehicle safety and passenger comfort. Summary of the invention.

[0003] The invention aims to solve this problem. In particular, it aims to provide a method and a device that enable a driver assistance system for a motor vehicle to take into account the variability of the vehicle's mass. Through this, the invention seeks to enable the provision of safer and more comfortable motor vehicles.

[0004] To achieve these objectives, the invention relates, according to a first aspect, to a method of managing, by means of a computer device embedded in a motor vehicle, the operation of a vehicle driver assistance system which

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[0009] controlling at least one chassis actuator of the vehicle, the method comprising the steps of: i. obtain data characterizing at least one measure of the steering angle of the front wheels of the vehicle, data characterizing at least one measure of the longitudinal speed of the vehicle, data characterizing at least one measure of the yaw rate of the vehicle and data characterizing at least one measure of the lateral acceleration of the vehicle; ii. determine, based on the data obtained during step i), data characterizing an estimate of the yaw rate of the vehicle, data characterizing an estimate of the lateral acceleration of the vehicle, data characterizing an estimate of the mass of the vehicle and data characterizing an estimate of the variance of the error in estimating the mass of the vehicle; iii. determine data characterizing a first convergence rate of the measurement of yaw rate and the estimation of yaw rate and data characterizing a second convergence rate of the measurement of lateral acceleration and the estimation of lateral acceleration; iv. manage the operation of the driving assistance system based on data characterizing an estimate of the vehicle mass when it is established that the estimate of the variance of the error in estimating the vehicle mass is less than a first pre-established threshold value, that said first convergence rate is greater than or equal to a second pre-established threshold value and that said second convergence rate is greater than or equal to the second threshold value. According to one variant, step ii) can be carried out using an unscented Kalman filter. According to another variant, step i) can be carried out by interacting with the driver assistance system. According to yet another variant, the second threshold value can be equal to 90%. According to a second aspect, the invention relates to a device for managing the operation of a driver assistance system of a motor vehicle which controls at least one chassis actuator of the vehicle, the device comprising at least one information processing unit, including at least one processor, and a data storage medium configured to implement a method as described above. According to a third aspect, the invention relates to a computer program comprising program code instructions for executing the steps of a process as described above when said program is executed by at least one processor.

[0010] According to a fourth aspect, the invention relates to a medium usable in a computer on which a program as described above is recorded.

[0011] According to a fifth aspect, the invention relates to a motor vehicle which incorporates a device as described above. Brief description of the figures

[0012] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0013] [Fig-1] is a schematic illustration of a motor vehicle according to the invention;

[0014] [Fig.2] is a functional diagram of a device according to the invention;

[0015] [Fig.3] is a flowchart of the steps of a process according to the invention;

[0016] [Fig.4] are graphics illustrating the implementation of the process according to the invention;

[0017] [Fig.5] are graphics illustrating the implementation of the process according to the invention; And

[0018] [Fig.6] are graphics illustrating the implementation of the process according to the invention. Detailed description of the invention

[0019] Figure 1 schematically illustrates a motor vehicle 1 according to the invention. This vehicle conventionally comprises a driver assistance system 10, which controls at least one chassis actuator 20 of the vehicle, for example, a chassis actuator coupled to the vehicle's braking system. Advantageously, the vehicle 1 according to the invention also comprises a device 100 for managing the operation of a driver assistance system of a motor vehicle that controls at least one chassis actuator of the vehicle within the meaning of the present invention, as described below, which implements a method for managing the operation of a driver assistance system of a motor vehicle that controls at least one chassis actuator of the vehicle within the meaning of the present invention, as described below.

[0020] During implementation of the method, the device 100 according to the invention determines an estimate of the vehicle's mass using measurements accessible to the vehicle's driver assistance system, namely the steering angle of the vehicle's front wheels, the vehicle's longitudinal speed, its yaw rate, and its lateral acceleration. These real-time measurements are used to feed a fragrance-free Kalman filter, which produces an estimate of the vehicle's lateral acceleration, an estimate of its yaw rate, an estimate of its mass, and an estimate of the variance of the error in estimating the vehicle's mass. Then, after verifying the convergence between the measurements of lateral acceleration and yaw rate and the corresponding estimates produced by the filter, the device 100 manages the operation of the driver assistance system based on the estimated mass of the vehicle. This allows the driver assistance system 10 of the vehicle 1 according to the invention to take into account the variability of the mass of the vehicle 1, and thus offers the driver assistance system 10 of the vehicle 1 according to the invention the possibility of providing more precise commands to the chassis actuator 20 of the vehicle 1.

[0021] The device 100 for managing the operation of a driver assistance system for a motor vehicle that controls at least one chassis actuator of the vehicle according to the invention is illustrated in [Fig.2]. It is fundamentally a computer device that includes at least one information processing unit 101, comprising one or more processors, a data storage medium 102, on which is recorded in particular a program that includes program code instructions for the execution of the steps of the process according to the invention described below, and an input and output interface 103 allowing the reception and transmission of data.

[0022] Preferably, the device 100 according to the invention is housed on a separate computer and interacts via its input / output interface 103 and by means of a wired vehicle communication network (e.g., CAN, Ethernet) – represented in [Fig. 1] by the double-headed arrows – with the vehicle's driver assistance system 10. Alternatively, the device 100 according to the invention is an integral part of a computer of the vehicle's driver assistance system 10.

[0023] According to the invention, all the elements described above contribute to enabling the implementation, on board a motor vehicle, of a method for managing the operation of a vehicle driving assistance system which controls at least one chassis actuator of the vehicle, as described below in relation to [Fig.3]-6.

[0024] Figure 3 illustrates, by means of a flowchart, the steps of the method according to the invention. According to a first step 301 of the method according to the invention, the device 100 according to the invention obtains data characterizing at least one measurement of the steering angle of the front wheels of the vehicle j, data characterizing at least one measurement of the longitudinal speed of the vehicle (yj), data characterizing at least one measurement of the yaw rate of the vehicle (¢), and data characterizing at least one measurement of the lateral acceleration of the vehicle (yv or a^). Indeed, the equations of vehicle dynamics show that the yaw rate, lateral acceleration, and longitudinal speed of the vehicle depend on the mass of the vehicle (m), in particular the lateral acceleration and the yaw rate (¢) are such that:

[0025] y _ rv ULW11 +

[0026] #= yv , + + ■. i \ ; 7 . -

[0027] And to obtain the measurements of the aforementioned parameters, the device 100 according to the invention interacts with the driving assistance system 10, which, conventionally, is able to determine these measurements, for example by interacting with a steering angle sensor, an accelerometer and a yaw rate sensor on board the vehicle 1. In other words, the device 100 according to the invention advantageously initiates the implementation of the method according to the invention by obtaining measurements of four common parameters which are conventionally determined by the driving assistance systems of all modern vehicles.

[0028] Next, according to a second step 302 of the method according to the invention, the device 100 according to the invention determines, based on the data obtained during the first step, data characterizing an estimate of the yaw rate of the vehicle (θ), data characterizing an estimate of the lateral acceleration of the vehicle (αy), data characterizing an estimate of the mass of the vehicle (m), and data characterizing an estimate of the variance of the error in estimating the mass of the vehicle.

[0029] To determine this data, the device 100 according to the invention advantageously feeds a odorless Kalman filter, which determines the aforementioned estimates from the fundamental equations of vehicle dynamics. This estimator is parameterized so that the two reconstructed estimated quantities, ay and ay, converge rapidly to their respective measurements, V' and ay. This convergence is achieved when the vehicle mass estimated by means of the odorless Kalman filter converges to the actual vehicle mass. This approach offers several advantages. Indeed, unlike a packet-based identification method, the nonlinear estimator, which acts as a recursive identifier, updates the estimated mass as soon as new measurements are available, without the need to store input / output data packets that consume memory space on a computer.Furthermore, the ease of implementation of the fragrance-free Kalman filter (UKF) and its robustness allow for a better approximation of nonlinearities compared to an extended Kalman filter (EKF), because, unlike an extended Kalman filter, the fragrance-free Kalman filter does not use the calculation of a Jacobian matrix (a linearization of the system at an operating point) and this thus makes its implementation on real-time targets often less computationally expensive.

[0030] Next, according to a third step 303 of the method according to the invention, the device 100 according to the invention determines data characterizing a first convergence rate of the yaw rate measurement and the yaw rate estimation, and data characterizing a second convergence rate of the acceleration measurement lateral and lateral acceleration estimation. To do this, the device 100 according to the invention calculates the difference between the measurement and the corresponding estimate, which it weights according to the difference between the value measured at a given instant and the average of the measurements previously taken. Thus, at the end of this third step of the process, the device 100 according to the invention has advantageously determined the effectiveness of the Kalman filter for estimating the yaw rate and lateral acceleration of the vehicle. And, as already mentioned above, the convergence between the estimates of these parameters and their corresponding measurements implies the convergence of the mass estimate and the actual mass of the vehicle.

[0031] Finally, according to a fourth step 304 of the method according to the invention, the device 100 according to the invention manages the operation of the driver assistance system based on data characterizing an estimate of the vehicle's mass, provided that it establishes that the estimated variance of the error in estimating the vehicle's mass is less than a first predetermined threshold value, that the first convergence rate is greater than or equal to a second predetermined threshold value, for example, 90%, and that the second convergence rate is greater than or equal to the second threshold value, for example, 90%. In other words, when it establishes the convergence of the estimates of lateral acceleration and yaw rate with the measurements of these parameters and that the variance of the error in estimating the mass is low, the device 100 according to the invention considers that the estimate of the vehicle's mass can be used by the driver assistance system 10.It then proceeds by transmitting to the latter data characterizing a command to use the estimated mass of the vehicle, and the driver assistance system 10 executes the command upon receipt of the data.

[0032] Figure 4 illustrates, by means of graphs, the time evolution of the measurements of the parameters that feed the fragrance-free Kalman filter. From top to bottom, these are the longitudinal speed of the vehicle, the steering angle of the front wheels, the yaw rate of the vehicle, and the lateral acceleration of the vehicle. Figure 5 illustrates the results of the estimator using the measurements shown in the graphs of Figure 4. From top to bottom, these are the estimated and measured lateral acceleration, the estimated and measured yaw rate, the estimated total mass, the actual total mass of the vehicle, the margin of error + / - 5% of the actual total mass of the vehicle, and, at the very bottom, the estimated variance of the mass estimation error. This variance estimate is repeated in Figure 6 with a threshold indicating when the estimated mass is used.

[0033] Thus, thanks to the method and device according to the invention described above, a solution is provided to enable a driver assistance system of a motor vehicle to take into account the variability of the vehicle's mass. Through these means, the invention thus contributes to the provision of safer motor vehicles. and more comfortable.

Claims

1.

2.

3. Demands A method for managing, by means of a computer device (100) installed on board a motor vehicle (1), the operation of a driver assistance system (10) of the vehicle which controls at least one chassis actuator (20) of the vehicle, characterized in that the method comprises the steps of: i. obtain data characterizing at least one measure of the steering angle of the front wheels of the vehicle, data characterizing at least one measure of the longitudinal speed of the vehicle, data characterizing at least one measure of the yaw rate of the vehicle and data characterizing at least one measure of the lateral acceleration of the vehicle; ii. determine, based on the data obtained during step i), data characterizing an estimate of the yaw rate of the vehicle, data characterizing an estimate of the lateral acceleration of the vehicle, data characterizing an estimate of the mass of the vehicle and data characterizing an estimate of the variance of the error in estimating the mass of the vehicle; iii. determine data characterizing a first convergence rate of the measurement of yaw rate and the estimation of yaw rate and data characterizing a second convergence rate of the measurement of lateral acceleration and the estimation of lateral acceleration; iv. manage the operation of the driving assistance system based on data characterizing an estimate of the vehicle mass when it is established that the estimate of the variance of the error in estimating the vehicle mass is less than a first pre-established threshold value, that said first convergence rate is greater than or equal to a second pre-established threshold value and that said second convergence rate is greater than or equal to the second threshold value. A process according to claim 1, characterized in that step ii) is carried out using a fragrance-free Kalman filter. A method according to any one of the preceding claims, characterized in that that step i) is carried out by interacting with the driver assistance system.

4. A method according to any one of the preceding claims, characterized in that the second threshold value is equal to 90%.

5. Device (100) for managing the operation of a driver assistance system (10) of a motor vehicle (1) which controls at least one chassis actuator (20) of the vehicle, characterized in that the device comprises at least one information processing unit (101), comprising at least one processor, and a data storage medium (102) configured to implement a method according to any one of the preceding claims.

6. Computer program comprising program code instructions for carrying out the steps of a process according to any one of claims 1 to 4 when said program is executed by at least one processor.

7. A medium usable in a computer, characterized in that a program according to claim 6 is stored thereon.

8. Motor vehicle, characterized in that it incorporates a device according to claim 5.

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