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

Abstract

The invention describes a method for driving dynamics control of a vehicle, wherein the vehicle has a plurality of actuators having different operating principles, comprising at least one first and one second multi-dimensional mathematical model, which map at least one set of driving dynamics of the vehicle about two axes of the vehicle, in particular the yaw and pitch behaviour of the vehicle, wherein the mathematical models constitute part of feedforward control and differ from one another in the number of control variables, wherein the second mathematical model has at least one more control variable than the first mathematical model and wherein the feedforward control is used to establish values for the at least one control variable of the models for driving dynamics control of the vehicle. The invention further relates to a corresponding device and computer program for driving dynamics control of a vehicle and a corresponding machine-readable storage medium.

Description

[0001] R. 410744 - 1 -Description: Method, device, and computer program for controlling the driving dynamics of a vehicle, as well as a corresponding machine-readable storage medium. 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: Modern driving dynamics control systems are already capable of influencing the dynamics of a vehicle along its six degrees of freedom with the help of different actuators (braking system, 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. It is common practice to assign at least one dedicated controller to each actuator, with these controllers then working in parallel to impose a control variable on each actuator.The individual controllers, for example in the area of ​​lateral dynamics control, are usually yaw rate controllers. The disadvantage here is the increased coordination effort between the individual controllers, which results from the coupling of degrees of freedom and the feedback between the individual sub-controllers in this coexisting solution approach. 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 a significantly increased integration and calibration effort, whereby a compromise must always be found between the individual sub-controllers. This approach therefore leads to very... R. 410744 - 2 -Complex controllers, which require a multitude of characteristic curves, activation and deactivation conditions, control thresholds, hysteresis elements, and the like. On the other hand, an integrated control approach for lateral dynamics control is already known from EP 2832599 A1, which can control several actuators using a cascade feedforward control depending on a desired driving behavior. Due to this cascade feedforward control, the coordination effort and complexity of the controller tuning for the area of ​​lateral dynamics control can already be significantly reduced. However, an increased coordination effort to combine the longitudinal and vertical dynamics control with the manipulated variables of the lateral dynamics control still remains. Disclosure of the Invention Advantages of the Invention A method for controlling the driving dynamics of a vehicle with the features of the independent patent claim is disclosed.The vehicle has several actuators with different operating principles. The method comprises at least a first and a second multidimensional mathematical model, which map 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. 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 manipulated variable of the models for controlling the vehicle's driving dynamics. This is advantageous because it enables an observation of the driving behavior at a higher level, up to the overall vehicle level, and the dependencies between sub-models for the different dynamics, such as yaw and pitch behavior, are explicitly mapped.Furthermore, the vehicle design can. R. 410744 - 3 -This can be done better, as this type of control better reflects the driving experience for all vehicle occupants. Thus, the desired vehicle behavior can be better specified in all relevant areas. The method can, for example, be implemented by computer. Further advantageous embodiments of the present invention are the subject of the dependent claims. The pilot control expediently comprises a cascade pilot control, or the pilot control is designed as a cascade pilot control, with the at least two mathematical models within the cascade pilot control being connected to one another in a cascade-like manner. This is advantageous because the actuators and the influences that can be achieved thereby can be advantageously taken into account and implemented in the cascade pilot control.Conveniently, the feedforward control includes a 6-degree-of-freedom feedforward control, so that lateral dynamics, longitudinal dynamics, 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. Conveniently, at least one actuator of the vehicle is controlled as a function of at least one determined manipulated variable. This is advantageous for directly achieving the desired target behavior of the vehicle. Conveniently, the first mathematical model has no manipulated 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 manipulated variables as feedforward control.The mathematical models expediently use physical vehicle parameters, in particular spring stiffness, damping properties, moments of inertia around the longitudinal and transverse axes of the vehicle, position of the. R. 410744 - 4 -Center of gravity, vehicle wheelbase, and / or wheel suspension geometry. This is advantageous because it allows for natural vehicle behavior. Depending on the at least one manipulated variable from the pilot control, at least one further manipulated variable adapted to the actuator characteristics is expediently determined. This is advantageous because it ensures that each actuator is assigned the various pilot control measures according to the tuning philosophy and / or its actuator properties. The at least one further manipulated variable is expediently determined for at least one of the following actuators: wheel brake, adjustable damper, roll stabilizer, air spring, drive train, here in particular a drive motor. This is advantageous because vehicles today typically have at least one of the aforementioned actuators.The invention further relates to a device for controlling the driving dynamics of a vehicle, the device comprising at least one means, in particular an electronic control unit, the means being configured to carry out the steps of a method according to the invention. The aforementioned advantages can thus be achieved. The invention further relates to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of a method according to the invention. The aforementioned advantages can thus be achieved. The invention further relates to a machine-readable storage medium on which the computer program according to the invention is stored. The aforementioned advantages can thus be achieved. Brief description of the drawings. R. 410744 - 5 -Advantageous embodiments of the invention are illustrated in the figures and explained in more detail in the following description. Figure 1 shows a flowchart of a method according to the invention for controlling the driving dynamics of a vehicle according to a first embodiment; 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; Figure 3 shows a schematic representation of a pilot control according to the invention with determination of further manipulated variables adapted to actuator characteristics; Figure 4 shows a schematic representation of a motor vehicle with various actuators; and Figure 5 shows a schematic representation of a control loop that implements a method according to the invention. Embodiments of the Invention: The same reference numerals denote the same device components or the same method steps in all figures.Figure 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. R. 410744 - 6 -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 about two axes. This can be, for example, a yaw and a pitch behavior of the vehicle, with the corresponding yaw and pitch dynamics being represented in the models. The mathematical models are part of a feedforward control and differ from one another in the number of manipulated variables. The second mathematical model has at least one more manipulated variable than the first mathematical model. This allows for a more targeted influence on the behavior. In a second step S12, values ​​for the at least one manipulated variable of the models for controlling the vehicle's driving dynamics are determined by the feedforward control.This at least one manipulated variable can, for example, comprise a yaw moment and / or a pitching moment, which are to be imposed on the vehicle. Typically, the feedforward control is part of an overall control system with corresponding controlled variable feedback. Figure 2 shows a flowchart of an inventive method 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 a first and a second multi-dimensional 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 a rolling behavior of the vehicle, with the corresponding pitching and rolling dynamics being represented in the models. The mathematical models are part of a feedforward control and differ from one another in the number of manipulated variables.The second mathematical model has at least one more manipulated variable than the first mathematical model. Furthermore, the mathematical models include physical... R. 410744 - 7 -cal vehicle parameters, in particular spring stiffness, 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. In a second step S22, the feedforward control determines values ​​for at least one manipulated variable of the models for controlling the vehicle's driving dynamics. This at least one manipulated variable can, for example, comprise a pitching moment and / or a rolling moment that are to be imposed on the vehicle. In a third step S23, at least one further manipulated variable adapted to the actuator characteristics is determined depending on the at least one manipulated variable. This can be done, for example, as shown below. The feedforward control thus produces pitching moments (^^,^^) and rolling moments or rolling moments (^^,^^) for each individual actuator.These pitch and roll moments are then converted into control variables (^) that are suitable 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. 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 applied braking force acts as a vertical component on the vehicle body via the suspension. With the help of the brake support angle ^ determined by the wheel suspension geometry. ^ , so- R. 410744 - 8 - such as the track width ^ and the dynamic wheel radius ^^^^, the respective axle-wise influence of a differential braking torque between the left and right wheel ∆^ can be calculated as follows: ^ on the roll moment ^ ^,^^ be determined: With the additional condition that the yaw dynamics of the vehicle remain unaffected, i.e. the yaw moment ^^ remains equal to 0, the following relationship can be found between the differential braking torque of the front axle ∆^ ^,^^ and rear axle ∆^ ^,^^ manufactured: This results in the calculation of the differential braking torques ∆^ ^,^^ and ∆^ ^,^^ to set a target roll moment ^ ^,^^taking into account the influence on yaw dynamics, the following: 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 determines a portion of the applied braking or driving force. ^ as a vertical component via the suspension on the vehicle body. R. 410744 - 9 - Using the brake support angle given by the wheel suspension geometry ^ ^ or drive support angle ^ ^ as well as the position of the center of gravity^^^^^^^ , ^^^^^^^ between the axles and the dynamic wheel radius ^^^^the respective axle-wise influence of a wheel brake or wheel drive torque ^ ^ on the pitching moment ^ ^,^^ be determined: For simplification in the further calculations, coefficients ^ ^^ and ^ ^^ formed, which represent the geometric properties of the vehicle: Assuming that a distribution factor ^^ ^^ the driver's desired longitudinal torque^^,^^^^^^ is distributed between the front and rear axle, the following relationship between the distribution factor and the longitudinal torques ^ ^,^^ and ^ ^,^^ of the axes are taken: ^^,^^ = ^^^^ ∙ ^^,^^^^^^^^,^^ = (1 − ^^^^) ∙ ^^,^^^^^^The calculation for the distribution factor is as follows ^^ ^^ , which represents the actuation of a given pitching moment ^ ^,^^ taking into account the driver's desired longitudinal torque ^ ^,^^^^^^ and the geometric properties ^ ^^ and ^ ^^ of the vehicle allowed: R. 410744 - 10 - Analogous to the examples already explained, control variables adapted to the actuator characteristics can also be derived for other actuators (braking system, chassis systems, steering systems, etc.) from pitch and roll moments from the pilot control cascade. By combining the moments calculated in the pilot control cascade, the vehicle behavior can be influenced and characterized at the overall vehicle level. In a fourth step S24, at least one actuator of the vehicle is controlled depending on at least one further control variable. This allows the desired vehicle behavior to be achieved. Figure 3 shows a schematic representation of how further control variables adapted to the 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 pilot control 32 as the basis for calculating the corresponding yaw, pitch, and / or roll moments.These torques are then translated into respective actuator-specific control variables depending on the available or to be controlled actuator, which takes place in block 33. Subsequently, corresponding actuators 34, 35, and 36 are controlled accordingly. 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, 41, 41d. It also 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 viewed as an actuator or actuators. In addition, the vehicle has roll stabilizers 45a, 45b. R. 410744 - 11 -The listed actuators can be controlled by the pilot control or vehicle dynamics control. Figure 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 pilot control and implements the models and manipulated variable value determination explained above. In the present case, three mathematical models are implemented in the pilot control 52, for example, with which a roll, pitch, and yaw moment are determined, which are suitably implemented in a controlled vehicle. To compensate for any model inaccuracies, a feedback to 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.

Claims

R. 410744 - 12 - Claims 1. Verfahren zur Fahrdynamikregelung eines Fahrzeugs, wobei das Fahrzeug has several actuators with different operating principles, comprising m indestens ein erstes und ein zweites mehrdimensionales mathematisches Model which at least represents the driving dynamics of the vehicle around two axes es Fahrzeugs abbilden, insbesondere ein Gier- und ein Nickverhalten des Vehicle, whereby the mathematical models are part of a feedforward control and differ from each other in the number of manipulated variables, whereby the second mathematical model has at least one more manipulated variable a ls das erste mathematische Modell und wobei durch die Vorsteuerung Werte für die mindestens eine Stellgröße der Modelle zur Fahrdynamikregelung des Fahrzeugs ermittelt werden.

2. Verfahren gemäß dem vorhergehenden Anspruch, wobei die Vorsteuerung eine Kaskadenvorsteuerung umfasst, wobei die mindestens zwei mathemati- ical models are connected to each other in a cascade-like manner within the cascade feedforward control.

3. Verfahren gemäß einem der vorhergehenden Ansprüche, wobei die Vorsteu- lation includes a 6-degree-of-freedom feedforward control.

4. Verfahren gemäß einem der vorhergehenden Ansprüche, wobei mindestens an actuator of the vehicle is controlled depending on at least one determined control variable.

5. Verfahren gemäß einem der vorhergehenden Ansprüche, wobei das erste mathematische Modell keine Stellgröße aufweist.

6. Verfahren gemäß einem der vorhergehenden Ansprüche, wobei die mathe- matic models physical vehicle parameters, especially spring s teifigkeiten, Dämpfungseigenschaften, Trägheitsmoment um die Längs- und R. 410744 - 13 - Querachse des Fahrzeugs, Lage des Schwerpunkts, Radstand des Fahr- vehicle and / or wheel suspension geometry.

7. Verfahren gemäß einem der vorhergehenden Ansprüche, wobei in Abhängig-speed of the at least one manipulated variable from the feedforward control, at least one further manipulated variable adapted to the actuator characteristics is determined.

8. Verfahren gemäß dem vorhergehenden Anspruch, wobei die mindestens eine weitere Stellgröße für mindestens einen der folgenden Aktoren ermittelt wird: - Radbremse, - Verstelldämpfer, - Wankstabilisator, - Luftfeder, - Antriebsstrang, insbesondere ein Antriebsmotor.

9. Vorrichtung zur Fahrdynamikregelung eines Fahrzeugs, umfassend mindes- at least one means, in particular an electronic control unit, which erichtet ist, die Schritte des Verfahrens nach einem der Ansprüche 1 bis 8 to execute.

10. Computerprogramm, umfassend Befehle, die bei der Ausführung des Pro- program by a computer, causing it to carry out the steps of the process ens nach einem der Ansprüche 1 bis 8 auszuführen.

11. Maschinenlesbares Speichermedium, auf dem das Computerprogramm nach the above claim is stored.

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