Method, device and computer program for controlling the driving dynamics of a vehicle and corresponding machine-readable storage medium

Abstract

A method for controlling the driving dynamics of a vehicle is described, wherein the vehicle has a plurality of actuators with different operating principles, comprising at least a first and a second multi-dimensional mathematical model which depict at least one driving dynamics of the vehicle about two axes of the vehicle, in particular a yaw and pitch behavior of the vehicle, wherein the mathematical models are part of a feedforward control and differ from one another in the number of manipulated variables, wherein the second mathematical model has at least one more manipulated variable than the first mathematical model and wherein values ​​for the at least one manipulated variable of the models for controlling the driving dynamics of the vehicle are determined by the feedforward control. Furthermore, a corresponding device and computer program for controlling the driving dynamics of a vehicle as well as a corresponding machine-readable storage medium are described.

Description

[0001] The present invention is based on a method for controlling the driving dynamics of a vehicle according to the independent patent claim. State of the art

[0002] Modern vehicle dynamics control systems are already capable of influencing a vehicle's dynamics along its six degrees of freedom using various actuators (braking systems, chassis systems, steering systems, etc.). From the perspective of vehicle control systems, a distinction is usually made between the different disciplines of lateral dynamics, longitudinal dynamics, and vertical dynamics.

[0003] It is common practice to assign at least one dedicated controller to each actuator, with these controllers then working in parallel to each other to apply a manipulated variable to the actuators. In the area of ​​lateral dynamics control, for example, the individual controllers are usually yaw rate controllers. The disadvantage of this is the increased coordination effort between the individual controllers, which arises with this coexisting solution approach due to the coupling of degrees of freedom and the feedback between the individual sub-controllers. In addition, the various lateral dynamics, longitudinal dynamics, and vertical dynamics controllers sometimes access the same actuators, which is why the different manipulated variables of these controllers must be prioritized and weighted. This also leads to significantly increased integration and calibration effort, whereby a compromise must always be found between the individual sub-controllers.This approach therefore leads to very complex controllers, which require a large number of characteristics, activation and deactivation conditions, control thresholds, hysteresis elements and the like.

[0004] On the other hand, an integrated control approach for lateral dynamics control is already known from EP 2 832 599 A1, which can control multiple actuators using cascade feedforward control depending on a desired driving behavior. This cascade feedforward control can already significantly reduce the coordination effort and complexity of controller tuning for lateral dynamics control. However, increased coordination effort remains to combine longitudinal and vertical dynamics control with the manipulated variables of lateral dynamics control. Disclosure of the inventionAdvantages of the invention

[0005] A method for controlling the driving dynamics of a vehicle is disclosed, having the features of the independent patent claim. The vehicle has a plurality of actuators with different operating principles. The method comprises at least a first and a second multidimensional mathematical model, which represent at least one driving dynamic of the vehicle about two axes of the vehicle, in particular a yaw and pitch behavior of the vehicle. The mathematical models are part of a feedforward control and differ from one another in the number of manipulated variables.

[0006] The second mathematical model has at least one more manipulated variable than the first mathematical model. The feedforward control determines values ​​for at least one of the manipulated variables of the models used to control the vehicle's driving dynamics.

[0007] This is advantageous because it allows for a higher-level examination of driving behavior, right up to the overall vehicle level, and explicitly maps the dependencies between submodels for different dynamics such as yaw and pitch behavior. Furthermore, vehicle design can be improved because this type of control better reflects the driving experience for all vehicle occupants. Thus, the desired vehicle behavior can be more accurately specified in all relevant areas.

[0008] The process can, for example, be implemented by computer.

[0009] Further advantageous embodiments of the present invention are the subject of the subclaims.

[0010] The pre-control system advantageously comprises a cascade pre-control system or is designed as a cascade pre-control system, with the at least two mathematical models within the cascade pre-control system being cascade-connected. This is advantageous because the actuators and the influences achievable thereby can be advantageously considered and implemented in the cascade pre-control system.

[0011] Conveniently, the feedforward control includes a 6-degree-of-freedom feedforward control, so that both lateral, longitudinal, and vertical dynamics are taken into account in the feedforward control. This is advantageous for influencing the vehicle as desired in all spatial degrees of freedom.

[0012] It is advisable to control at least one actuator of the vehicle depending on at least one determined control variable. This is advantageous for directly achieving the desired target behavior of the vehicle.

[0013] Conveniently, the first mathematical model does not have a control variable. This is advantageous because it achieves natural driving dynamics behavior that does not feel artificial or "like control interventions" to the driver. The driving behavior is thus advantageously influenced by predeterminable physical properties of the vehicle, which result in corresponding control variables as feedforward control.

[0014] The mathematical models advantageously use physical vehicle parameters, in particular spring stiffness, damping properties, moments of inertia around the vehicle's longitudinal and transverse axes, the position of the center of gravity, the vehicle's wheelbase, and / or the suspension geometry. This is advantageous because it allows for natural vehicle behavior.

[0015] It is advisable to determine at least one additional control variable adapted to the actuator characteristics depending on the at least one control variable from the feedforward control. This is advantageous because it ensures that the various feedforward control measures are assigned to each actuator according to the tuning philosophy and / or its actuator characteristics.

[0016] Conveniently, at least one additional control variable is determined for at least one of the following actuators: wheel brake, adjustable damper, roll stabilizer, air spring, drive train, in this case, in particular a drive motor. This is advantageous since modern vehicles typically have at least one of the aforementioned actuators.

[0017] Furthermore, the invention relates to a device for controlling the driving dynamics of a vehicle, wherein the device comprises at least one means, in particular an electronic control unit, wherein the means is configured to carry out the steps of a method according to the invention. Thus, the aforementioned advantages can be achieved.

[0018] Furthermore, the invention relates to a computer program comprising instructions that, when executed by a computer, cause the computer to perform the steps of a method according to the invention. Thus, the aforementioned advantages can be achieved.

[0019] Furthermore, the invention relates to a machine-readable storage medium on which the computer program according to the invention is stored. Thus, the aforementioned advantages can be achieved. Short description of the drawings

[0020] Advantageous embodiments of the invention are illustrated in the figures and explained in more detail in the following description.

[0021] They show: Fig. 1 is a flowchart of a method according to the invention for controlling the driving dynamics of a vehicle according to a first embodiment; Fig. 2 shows a flowchart of a method according to the invention for controlling the driving dynamics of a vehicle according to a second embodiment; Fig. 3 a schematic representation of a feedforward control according to the invention with determination of further manipulated variables adapted to actuator characteristics; Fig. 4 a schematic representation of a motor vehicle with various actuators; and Fig. 5 a schematic representation of a control loop that implements a method according to the invention. Embodiments of the invention

[0022] The same reference numerals denote the same device components or the same process steps in all figures.

[0023] Fig. 1 shows a flowchart of a method according to the invention for controlling the driving dynamics of a vehicle according to a first embodiment. The vehicle has several actuators with different operating principles, for example, at least one wheel brake, adjustable damper, roll stabilizer, air spring, and / or a drive train, in particular in the form of a drive motor.

[0024] In a first step S11 of the method, at least one first and one second multidimensional mathematical model are provided, each of which represents at least one driving dynamic of the vehicle around two axes. This can, for example, be the yaw and pitch behavior of the vehicle, with the corresponding yaw and pitch dynamics being represented in the models.

[0025] The mathematical models are part of a feedforward control and differ from each other in the number of manipulated variables. The second mathematical model has at least one more manipulated variable than the first. This allows for a more targeted influence on behavior.

[0026] In a second step S12, the feedforward control determines values ​​for the at least one manipulated variable of the models for controlling the vehicle's driving dynamics. This at least one manipulated variable can, for example, include a yaw moment and / or a pitch moment that are to be applied to the vehicle. Typically, the feedforward control is part of an overall control system with corresponding controlled variable feedback.

[0027] Fig. Figure 2 shows a flowchart of a method according to the invention for controlling the driving dynamics of a vehicle according to a second embodiment. As above, in a first step S21 of the method, at least one first and one second multidimensional mathematical model are provided, each of which represents at least one driving dynamic of the vehicle about two axes of the vehicle. This can, for example, be a pitching and rolling behavior of the vehicle, with the corresponding pitching and rolling dynamics being represented in the models.

[0028] The mathematical models are part of a feedforward control and differ from one another in the number of control variables. The second mathematical model has at least one more control variable than the first. Furthermore, the mathematical models include physical vehicle parameters, in particular spring stiffness, damping properties, moment of inertia around the vehicle's longitudinal and transverse axes, position of the center of gravity, vehicle wheelbase, and / or wheel suspension geometry.

[0029] In a second step S22, the feedforward control determines values ​​for the at least one control variable of the models for controlling the vehicle's driving dynamics. This at least one control variable can, for example, include a pitching moment and / or a rolling moment that are to be applied to the vehicle.

[0030] In a third step S23, at least one further manipulated variable adapted to the controller or actuator characteristics is determined depending on the at least one manipulated variable. This can be done, for example, as shown below.

[0031] The pre-control thus results in pitching moments (M y,FF ) and roll moments (M x,FF ) for each individual actuator. These pitch and roll moments are then converted into control variables (u) that are appropriate for the actuators and adapted to the respective characteristics of the individual actuators and the overall vehicle, taking into account, for example, the wheel suspension geometry. Depending on the nature and operating principle of an actuator, a pitch moment, a roll moment, or a combination of pitch and roll moments can be converted into a corresponding control variable.

[0032] For example, pitch and roll moments can be implemented using braking torque requests to the wheel brakes or via a target force request for a wheel-specific chassis system. The following example discusses the explicit calculation of wheel-specific braking torques based on a roll moment resulting from the pilot control cascade, under the additional boundary condition that the yaw dynamics should not be influenced. The geometry of the wheel suspension plays a major role here, as part of the distributed braking force acts as a vertical component via the suspension on the vehicle body. Using the brake support angle θ determined by the wheel suspension geometry, b , as well as the track width S and the dynamic wheel radius r dyn The axle-wise influence of a differential braking torque between the left and right wheel ΔM b on the roll moment M x,FF be determined: Mx,FF=−ΔMb,FA⋅tanθb,FA⋅SFA2 rdyn,FA+ΔMb,RA⋅tanθb,RA⋅SRA2 rdyn,RA

[0033] With the additional condition that the yaw dynamics of the vehicle remain unaffected, i.e. the yaw moment M z remains equal to 0, the following relationship can be found between the differential braking torque of the front axle ΔM b,FA and rear axle ΔM b,RA are manufactured: ΔMb,FA⋅SFArdyn,FA=ΔMb,RA⋅SRArdyn,RA

[0034] This results in the calculation of the differential braking torques ΔM b,FA and ΔM b,RA to obtain a target roll moment M x,FF taking into account the influence on yaw dynamics, the following: ΔMb,FA=−2Mx,FFrdyn,FASFA(1tanθb,FA+tanθb,RA) ΔMb,RA=2Mx,FFrdyn,RASFA(1tanθb,FA+tanθb,RA)

[0035] The following also provides an example of calculating a drive and braking torque distribution for actuating a pitching moment resulting from the pilot control cascade. The geometry of the wheel suspension also plays a major role, as it is responsible for a portion of the applied braking or driving force F x as a vertical component acting on the vehicle body via the suspension.

[0036] Using the brake support angle θ given by the wheel suspension geometry b or drive support angle θ a and the position of the center of gravity l FA2COG , l RA2COG between the axles and the dynamic wheel radius r dyn The axle-wise influence of a wheel brake or wheel drive torque M x on the pitching moment M y,FF be determined: My,FF=Mx,FA⋅tanθa / b,FA⋅lFA2COGrdyn,FA+Mx,RA⋅tanθa / b,RA⋅tanθa / b,RA⋅lRA2COGrdyn,RA

[0037] For simplification in the further calculations, coefficients C FA and C RA formed, which represent the geometric properties of the vehicle: CFA=tanθa / b,FA⋅lFA2COGrdyn,FA CRA=tanθa / b,FA⋅lFA2COGrdyn,FA

[0038] Assuming that a distribution factor Co FA the driver's desired longitudinal torque M x,Driver distributed between the front and rear axle, the following relationship between the distribution factor and the longitudinal moments M x,FA and M x,RA the axes are hit: Mx,FA=CoFA⋅Mx,Driver Mx,FA=(1−CoFA)⋅Mx,Driver

[0039] The calculation for the distribution factor Co is as follows: FA , which represents the actuation of a given pitching moment M y,FF taking into account the driver's desired longitudinal torque M x,Driverand the geometric properties C FA and C RA of the vehicle allowed: CoFA=My,FFMx,Driver−CRACFA−CRA

[0040] Analogous to the examples already explained, control variables adapted to the actuator characteristics can also be derived from pitch and roll moments from the pilot control cascade for other actuators (braking systems, chassis systems, steering systems, etc.). By combining the moments calculated in the pilot control cascade, the vehicle behavior can be influenced and developed at the overall vehicle level.

[0041] In a fourth step S24, at least one actuator of the vehicle is controlled depending on the at least one further manipulated variable. Thus, the desired vehicle behavior can be achieved.

[0042] Fig. Figure 3 shows a schematic representation of how additional control variables adapted to actuator characteristics are determined. A driver input 31, for example, the steering angle, which the driver controls via the steering wheel, is used within the feedforward control 32 as the basis for calculating the corresponding yaw, pitch, and / or roll moments. These moments are then translated into actuator-specific control variables depending on the available or to be controlled actuator, which occurs in block 33. Subsequently, the corresponding actuators 34, 35, and 36 are controlled accordingly.

[0043] Fig. Figure 4 shows a schematic representation of a motor vehicle 40 with various actuators. The motor vehicle 40 has, among other things, four wheel brakes 41a, 41b, 41c, 41d. Furthermore, it has four adjustable dampers 42a, 42b, 42c, 42d, and four air springs 43a, 43b, 43c, 43d. Furthermore, the drive train, here in particular the motors 44a and 44b, can be considered as an actuator or actuators. In addition, the vehicle has roll stabilizers 45a, 45b.

[0044] The listed actuators can be controlled by the feedforward control or vehicle dynamics control.

[0045] Fig.5 shows a schematic representation of a control loop 50 that implements a method according to the invention. In block 51, the steering angle desired or specified by the driver is taken into account in the control loop 50. Block 52 forms the feedforward control and implements the models and manipulated variable value determination explained above. In the present case, three mathematical models are implemented in the feedforward control 52, which, for example, determine a roll, pitch, and yaw moment, which are suitably implemented in a controlled vehicle. To compensate for any model inaccuracies, a feedback loop for the control system is provided in block 53. In block 54, the determined moments can, if necessary, be converted into manipulated variables for individual actuators, as explained above, before they are applied there. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 832 599 A1

[0004]

Claims

[1] Method for controlling the driving dynamics of a vehicle, the vehicle having a plurality of actuators with different operating principles, comprising at least a first and a second multi-dimensional mathematical model, which represent at least one driving dynamics of the vehicle about two axes of the vehicle, in particular a yaw and a pitch behavior of the vehicle, the mathematical models being part of a feedforward control and differing from one another in the number of manipulated variables, the second mathematical model having at least one more manipulated variable than the first mathematical model and the feedforward control determining values for the at least one manipulated variable of the models for controlling the driving dynamics of the vehicle. [2] Method according to the preceding claim, wherein the feedforward control comprises a cascade feedforward control, wherein the at least two mathematical models are connected to one another in a cascade manner within the cascade feedforward control. [3] Method according to one of the preceding claims, wherein the feedforward control comprises a 6-degree-of-freedom feedforward control. [4] Method according to one of the preceding claims, wherein at least one actuator of the vehicle is controlled as a function of at least one determined control variable. [5] Method according to one of the preceding claims, wherein the first mathematical model has no manipulated variable. [6] Method according to one of the preceding claims, wherein the mathematical models use physical vehicle parameters, in particular spring stiffnesses, damping properties, moment of inertia about the longitudinal and transverse axes of the vehicle, position of the center of gravity, wheelbase of the vehicle and / or wheel suspension geometry. [7] Method according to one of the preceding claims, wherein at least one further manipulated variable adapted to actuator characteristics is determined as a function of the at least one manipulated variable from the pre-control. [8] Method according to the preceding claim, wherein the at least one further control variable is determined for at least one of the following actuators: - wheel brake, - adjustable damper, - roll stabilizer, - air spring, - Drive train, in particular a drive motor. [9] Device for controlling the driving dynamics of a vehicle, comprising at least one means, in particular an electronic control unit, which is designed to carry out the steps of the method according to one of claims 1 to 8. [10] A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to any one of claims 1 to 8. [11] A machine-readable storage medium on which the computer program according to the preceding claim is stored.

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