Method for determining performance difference between target performance and actual performance of vehicle actuator

Abstract

The invention relates to a method (1) for determining a performance difference (3) of a vehicle actuator (302). The method (1) comprises: ascertaining (9) a target value (DoF-Soll) of degree of freedom of motion; ascertaining (11) a manipulated variable expected value (St-EW); ascertaining (13) an actual value (DoF-Ist) of the degree of freedom of motion; a manipulated variable actual value (St-Ist) is ascertained (15) and a manipulated variable maximum value (St-Max) is ascertained (17). The method further comprises determining (19) a performance difference (3) of the vehicle actuator (302) using the actual value of degree of freedom (DoF-Ist), the target value of degree of freedom (DoF-Soll), the actual value of manipulated variable (St-Ist), the desired value of manipulated variable (St-EW) and the maximum value of manipulated variable (St-Max); and ascertaining (21) an updated degree of freedom maximum (DoF-Max) of the vehicle (200) on the basis of the ascertained performance difference (3). The invention also relates to an actuator monitoring system (200) and a vehicle (300).

Description

Field of the Invention

[0001] The present invention relates to a method for determining a performance difference between a target performance and an actual performance of a vehicle actuator of a vehicle, wherein the vehicle actuator is configured to affect at least one degree of freedom of movement of the vehicle. The present invention also relates to an actuator monitoring system and a vehicle having the actuator monitoring system. Background Art

[0002] Vehicles have a large number of vehicle actuators that act on or are used to affect the degrees of freedom of movement of the vehicle. Thus, for example, the drive motor of a vehicle is typically used to accelerate the vehicle or to keep the speed of the vehicle constant in the face of resistances such as, in particular, air resistance and frictional resistance of the vehicle. Another example of a vehicle actuator is the braking system of the vehicle, which is configured to decelerate the vehicle, and the steering section of the vehicle. Vehicle actuators generally affect the degrees of freedom of movement of the vehicle over a certain period of time and must supply power for this purpose during this period of time. Therefore, the drive power (usually in kilowatts or horsepower) of the drive motor is a common parameter for the vehicle. However, other vehicle actuators also supply power. Thus, for example, the braking system of the vehicle must provide braking performance in order to reduce the speed of the vehicle.

[0003] Due to various influences, the performance of vehicle actuators can be restricted. That is, the drive power of the drive motor can be reduced due to a failure of the cylinders of the drive motor, due to poor lubrication and / or due to wear. The performance of the brakes of the vehicle can also sometimes or permanently be restricted. Thus, on a long downhill stretch, the brakes of the vehicle can be overloaded and heat up sharply. At a temperature of 400 °C or above, the braking performance of conventional friction brakes will generally weaken and the braking performance that can be provided by the brakes will decrease. This phenomenon is also referred to as fade. If a vehicle actuator cannot provide the performance that it is set up to provide in the actual state, then there is a performance difference between the actual performance and the target performance. Such a performance difference can be safety-critical, especially in the brakes or the steering section of the vehicle. Thus, for example, the brake discs of the braking system of the vehicle can rust after long periods of disuse, thereby reducing the braking performance that can be provided by the braking system. However, the driver of the vehicle may not recognize such a performance difference, so that the driver may control the vehicle inappropriately. If the required braking performance cannot be provided by the braking system at this time, an accident may occur. Summary of the Invention

[0004] Accordingly, it is an object of the present invention to provide a method that allows the performance difference of a vehicle to be determined and that provides increased safety. In addition, the object of the present invention also describes an actuator monitoring system and a vehicle that provide increased safety.

[0005] In a first aspect, the present invention solves this task by means of a method of the type described at the beginning, the method having the following steps: obtaining a target value of the degrees of freedom of movement of the vehicle; obtaining an expected value of the actuating quantity for achieving the target value of the degrees of freedom of movement; obtaining an actual value of the degrees of freedom of movement of the vehicle corresponding to the target value of the degrees of freedom of movement; obtaining an actual value of the actuating quantity provided to the vehicle actuator for achieving the actual value of the degrees of freedom of movement; obtaining a maximum value of the actuating quantity of the vehicle actuator; in the following cases, obtaining a performance difference of the vehicle actuator: the actual value of the degrees of freedom of movement is outside the tolerance of the degrees of freedom of movement around the target value of the degrees of freedom of movement, and the actual value of the actuating quantity is less than the maximum value of the actuating quantity; the actual value of the degrees of freedom of movement is outside the tolerance of the degrees of freedom of movement around the target value of the degrees of freedom of movement, the expected value of the actuating quantity corresponds to the maximum value of the actuating quantity, and the actual value of the actuating quantity corresponds to the maximum value of the actuating quantity; or the actual value of the degrees of freedom of movement corresponds to the target value of the degrees of freedom of movement, and the actual value of the actuating quantity required to achieve the actual value of the degrees of freedom of movement is outside the tolerance of the actuating quantity around the expected value of the actuating quantity. Preferably, the method further has: obtaining an updated maximum value of the degrees of freedom of movement of the vehicle based on the obtained performance difference.

[0006] The performance difference is not necessarily a parameter corresponding to physical power in watts. Thus, the performance difference can also be a difference in the force (such as braking force) that can be provided by the vehicle actuator, a difference in the torque that can be provided by the vehicle actuator, a difference in the current that can be provided by the vehicle actuator, a difference in the voltage that can be provided by the vehicle actuator, and / or a difference in the angle (especially the steering angle) that can be provided by the vehicle actuator. Thus, for example, the performance difference of a vehicle brake can also be identified by the fact that the actual braking force provided by the braking system or the brake of the braking system is less than the target braking force. The lower braking force then also results in lower braking performance.

[0007] By means of the method according to the invention, the performance difference, i.e. the deviation between the expected performance (target performance) and the actual performance of the vehicle actuator, can be obtained in at least two ways depending on the situation. If the target value of the degrees of freedom of movement (target value of the degrees of freedom of movement) is not reached or the target value of the degrees of freedom of movement is different from the actual value of the degrees of freedom of movement, the deviation is obtained if the expected value of the actuating quantity and the actual value of the actuating quantity correspond to the maximum value of the actuating quantity. For example, when, despite a maximum braking pressure of 10 bar being pre-given, even for the maximum braking pressure, the target value is 7 m / s 2 (target value of the degrees of freedom of movement = 7 m / s 2 ), but the deceleration of the vehicle is still only 5 m / s 2 (actual value of the degrees of freedom of movement = 5 m / s 2), which indicates that the braking system (vehicle actuator) of the vehicle cannot provide the desired deceleration (i.e., there is a performance difference in the braking system). This also applies if the target value of the degree of freedom of movement cannot be achieved, even if the actual value of the manipulated variable has not reached the maximum value of the manipulated variable. For example, this is the case when due to damage, a pre-given braking pressure limit, and / or thermal overload, only an actual value of the manipulated variable of 7 bar can be provided to one or more brakes of the braking system instead of a maximum value of the manipulated variable of 10 bar.

[0008] In the second variant, the actual value of the degree of freedom of movement corresponds to the target value of the degree of freedom of movement. Thus, for example, the desired deceleration of the vehicle of 3 m / s is achieved 2 . However, in order to achieve this deceleration, the actual value of the manipulated variable needs to be greater than the expected value of the manipulated variable. In the above example, in order to achieve the desired target deceleration, an actual braking pressure (actual value of the manipulated variable) of 6 bar must be provided instead of the expected braking pressure (expected value of the manipulated variable) of 4 bar. This situation may be caused by the fact that one or more brake discs in the braking system have rusted after long-term disuse, or the brake linings have become glass-smooth due to previous high thermal loads. It can also be inferred from the deviation between the actual value of the manipulated variable and the expected value of the manipulated variable that the performance of the vehicle actuator (the brake in this example) does not correspond to the expected performance.

[0009] The target value of the degree of freedom of movement is the target value of the degree of freedom of movement required for the vehicle by a human driver or a (semi-) autonomous unit (which is also referred to as a virtual driver). The degree of freedom of movement is preferably a change in the longitudinal dynamics of the vehicle, i.e., the longitudinal acceleration or longitudinal deceleration of the vehicle. Thus, the target value of the degree of freedom of movement is, for example, the deceleration of the vehicle required by the driver or the autonomous unit, such as 2 m / s 2 . The actual value of the degree of freedom of movement is related to the target value of the degree of freedom of movement, so that the actual value of the degree of freedom of movement and the target value of the degree of freedom of movement describe the degree of freedom of movement of the same driving situation. The actual value of the degree of freedom of movement and the target value of the degree of freedom of movement always relate to the same degree of freedom of movement.

[0010] The desired value of the actuating variable for the vehicle actuator is preferably predicted or estimated within the scope of the method. This means that the prediction or estimation involves determining which actuating variable must be supplied to the vehicle actuator in order to achieve the target value of the degree of freedom of movement. In the method, the desired value of the actuating variable is determined, where the desired value of the actuating variable indicates which value of the actuating variable must be supplied to the vehicle actuator according to the prediction in order to achieve the target value of the degree of freedom of movement. Preferably, the prediction is based on and / or made using the learned driving data of the vehicle. For example, the desired value of the actuating variable can be an actual value of the actuating variable that has been supplied to the vehicle actuator for a comparable or identical vehicle configuration and has resulted in an actual value of the degree of freedom of movement that is comparable to or corresponds to the target value of the degree of freedom of movement. Alternatively or additionally, the prediction can also be based on and / or made using a vehicle model. The desired value of the actuating variable is the value of the actuating variable that should be supplied to the vehicle actuator according to the prediction or estimation made to achieve the target value of the degree of freedom of movement.

[0011] The tolerance of the degree of freedom of movement is set to compensate for minor fluctuations in the actual value, which may be caused, for example, by measurement inaccuracies. Preferably, the tolerance of the degree of freedom of movement is 0% to 20% of the maximum value of the degree of freedom of movement, particularly preferably 3% to 5%. Thus, the tolerance of the degree of freedom of movement can be, for example, 5% of the maximum achievable deceleration of the vehicle. This means that, for example, if the deviation between the value of the actual degree of freedom of movement and the target value of the degree of freedom of movement exceeds 5% of the maximum value of the degree of freedom of movement, the actual degree of freedom of movement is no longer within the tolerance of the degree of freedom of movement. Preferably, the tolerance of the degree of freedom of movement is defined depending on the relevant degree of freedom of movement. Thus, if the degree of freedom of movement is the longitudinal deceleration of the vehicle, the tolerance of the degree of freedom of movement can have a relatively large value, while if the degree of freedom of movement is the lateral acceleration and / or the deflection ratio of the vehicle, the tolerance of the degree of freedom of movement can have a relatively small value.

[0012] Preferably, the degrees of freedom of movement tolerance and / or the manipulation quantity tolerance have a pre-given value. Furthermore preferably, the degrees of freedom of movement tolerance and / or the manipulation quantity tolerance can also be learned tolerances and / or dynamic tolerances. For example, the tolerance with a pre-given value can be known according to the specifications of the vehicle components, in particular known from sensors for detecting the actual value of the manipulation quantity and / or the actual value of the degrees of freedom of movement. Thus, for example, a pressure gauge may have a resolution and a delay that occurs when providing a measurement signal at its interface. This delay can be used to define the manipulation quantity tolerance. Therefore, the learned tolerance can be learned, for example, from comparison values of previous comparable driving situations (basically the same vehicle load, the same weather conditions and / or the same downhill gradient of the lane) and / or from comparison values known in driving tests. For example, if the vehicle deceleration at a braking pressure of 8 bar has led to a deceleration of 2 from 7.9 m / s 2 to 8.1 m / s 2 in previous driving situations, then the degrees of freedom of movement tolerance of 0.2 m / s

[0013] can be learned from these historical driving data. 2 Based on the known performance differences, the updated maximum degrees of freedom of movement of the vehicle can be known, which allows conclusions to be drawn about the vehicle. Thus, when there are performance differences in the braking system of the vehicle or one or more brakes, the maximum achievable vehicle deceleration can be known. For example, if the braking performance of 400 kW can be provided by the braking system under normal conditions without performance differences, but a relative performance difference of 50% has been known, then the updated maximum degrees of freedom of movement that can be known will not be the undisturbed maximum vehicle deceleration of 10 m / s 2 but only the updated maximum vehicle deceleration of 5 m / s

[0014] In a first preferred embodiment of the method, a performance difference of a vehicle actuator is detected only if the actual value of the degree of freedom of movement has been outside the tolerance of the degree of freedom of movement around the target value of the degree of freedom of movement for at least the difference time, or if the actual value of the amount of actuation required to achieve the target value of the degree of freedom of movement has been outside the tolerance of the amount of actuation around the expected value of the amount of actuation for at least the difference time. Preferably, the difference time has a value of 0.5 s or more, preferably 1 s or more, preferably 1.5 s or more, and particularly preferably 2 s. According to a preferred refinement, a performance difference and / or an updated maximum value of the degree of freedom of movement are detected only if the target-actual deviation of the degree of freedom of movement or the target-actual deviation of the amount of actuation has deviated from the respective tolerance for at least the difference time. This ensures that small deviations that may be caused, for example, by measurement inaccuracies do not immediately result in the detection of a performance difference. This improves the robustness of the method with respect to false detection. Preferably, the detection of the performance difference is carried out continuously, but the detection of the updated degree of freedom of movement is carried out only if the actual value of the degree of freedom of movement has been outside the tolerance of the degree of freedom of movement for at least the difference time and / or the actual value of the amount of actuation has been outside the tolerance of the amount of actuation for at least the difference time.

[0015] Preferably, detecting the target value of the degree of freedom of movement includes: detecting the planned driving trajectory of the vehicle by an autonomous unit; and detecting the target value of the degree of freedom of movement based on the driving trajectory. The driving trajectory includes at least one planned driving path (target driving path) that the vehicle has to drive along to complete a driving task. In addition, the driving trajectory also includes predefined parameters of the driving dynamics. The predefined parameters of the driving dynamics are preferably or include a speed predefined for driving along the driving path or a speed profile predefined for driving along the driving path. Thus, for example, based on the actual speed of the vehicle and the predefined speed included in the driven trajectory, the target deceleration required for the vehicle to decelerate from the actual speed to the predefined speed can be detected. The autonomous unit can be a fully autonomous unit or a semi-autonomous unit of the vehicle. The autonomous unit is preferably a virtual driver of the vehicle that is configured to autonomously control the vehicle. However, the autonomous unit can also be a unit of a driving assistance system (especially an adaptive cruise control system), in particular a control unit. Alternatively or additionally, detecting the target value of the degree of freedom of movement includes: detecting the adjustment travel of a control device; and detecting the target value of the degree of freedom of movement based on the detected adjustment travel. Thus, for example, the adjustment travel of a control device configured as a brake pedal can be detected and converted into a target deceleration using a known pedal characteristic curve.

[0016] In a preferred improvement, the method further has the following steps: in the case of knowing the performance differences of the vehicle actuators, knowing the driving dynamic boundary values of the vehicle in the case of using the known performance differences. Complying with the driving dynamic boundary values ensures safe and stable driving of the vehicle during normal operation. Preferably, the driving dynamic boundary values are or include the maximum allowable speed of the vehicle, the maximum allowable lateral acceleration, the maximum allowable vehicle acceleration, the maximum allowable vehicle deceleration, the maximum allowable steering angle gradient, the maximum allowable steering frequency or the minimum allowable corner radius. By means of the method according to the invention, multiple driving dynamic boundary values of the vehicle can also be defined, for example, the maximum allowable vehicle speed is defined as the first driving dynamic boundary value, and the maximum allowable lateral acceleration is defined as the second driving dynamic boundary value. For example, if the performance differences of the service brakes are known, the braking performance provided by the service brakes will be reduced compared to the braking performance under normal conditions. Then, the vehicle cannot decelerate at full power, which can be taken into account by setting the driving dynamic boundary values. Therefore, for example, the maximum vehicle deceleration that can be required by the driver can be delimited by the driving dynamic boundary values. The driver can take this limit into account when planning to start braking and / or when evaluating the braking distance. Similarly, for example, the steerable angular velocity that can be required can also be delimited.

[0017] Preferably, the method further has: re-knowing the planned driving trajectory in the case of using the known driving dynamic boundary values. The re-knowing of the planned driving trajectory can be a complete re-knowing of the planned driving trajectory, a partial re-knowing of the planned driving trajectory and / or an update of the planned driving trajectory. Therefore, there is a case of partial re-knowing when the trajectory curve or path including the planned driving trajectory is retained and at the same time the speed profile corresponding to driving along this trajectory curve included in the planned driving trajectory is re-known. In the case of partial re-knowing, preferably all the information and / or data on which the driving trajectory planning is based are re-known. In the case of an update, preferably only some of the information and / or data on which the driving trajectory planning is based are re-known. Therefore, the known driving dynamic boundary values are taken into account in the driving trajectory, thereby improving the safety during vehicle use.

[0018] In a preferred design, the expected value of the actuating variable for the vehicle actuator to achieve the target value of the degree of freedom of movement is determined using the actually measured value of the actuating variable learned for the learned target value of the degree of freedom of movement, and these learned target values of the degree of freedom of movement are within the tolerance of the degree of freedom of movement around the target value of the degree of freedom of movement. The expected value of the actuating variable is an estimate of the actuating variable that must be pre-specified in order to achieve the target value of the degree of freedom of movement. This estimate can be achieved particularly easily using the actually measured value of the actuating variable learned for a comparable target value of the degree of freedom of movement. A comparable target value of the degree of freedom of movement is a learned target value of the degree of freedom of movement whose value is within the tolerance of the degree of freedom of movement, and this tolerance has a width of at most 10%, preferably at most 5%, preferably at most 3%, preferably at most 2%, and particularly preferably at most 1.5% around the corresponding target value of the degree of freedom of movement. For example, the expected value of the braking pressure (actuating variable) that must be adjusted to achieve a vehicle deceleration of 2 m / s 2 can be determined based on the learned braking pressure that results in the vehicle deceleration being within the range of 1.8 m / s 2 to 2.2 m / s 2 . As an alternative or in addition, if the degree of freedom of movement is or includes deceleration, the required braking pressure for the target deceleration is preferably determined based on the parameters of the vehicle's electronic braking system.

[0019] Preferably, determining the expected value of the actuating variable for the vehicle actuator to achieve the target value of the degree of freedom of movement includes: determining the environmental data of the vehicle and determining the expected value of the actuating variable using the environmental data. The accuracy of the determined expected value of the actuating variable can be improved by using the environmental data. Therefore, the difference between the target value of the degree of freedom of movement and the actual value of the degree of freedom of movement can be based in whole or in part on factors that are independent of the vehicle actuator. Thus, for example, when the vehicle is driving on an icy road surface, the deceleration achieved during vehicle braking may be less than the expected target deceleration. This situation can be taken into account, for example, by reducing the target value of the degree of freedom of movement by using the environmental data. The environmental data is preferably or includes weather data, but can also be or include other environmental data, such as data on the quality of the road surface of the driving lane.

[0020] In a preferred design, obtaining the expected value of the actuating quantity for achieving the target value of the degree of freedom of movement of the vehicle includes: obtaining the vehicle data of the current configuration of the vehicle and obtaining the expected value of the actuating quantity using the vehicle data. The current vehicle configuration relates not only to vehicle-specific aspects but also to cargo-specific aspects. In addition to the geometric characteristics of the vehicle, the current vehicle configuration also includes load characteristics. The load characteristics represent the loads acting on the vehicle, and these loads may, for example, result from the vehicle's own weight and may also result from the vehicle's cargo. Therefore, the current vehicle configuration of an unloaded vehicle is different from that of the same vehicle in the loaded state. The load characteristics may preferably be or include wheel loads, axle loads, gross vehicle mass, the mass of vehicle parts, and / or the position of the center of gravity of the vehicle or of vehicle parts. In addition, the load characteristics may preferably also include data representing wheel loads, axle loads, gross vehicle mass, and / or the mass of vehicle parts. The current vehicle configuration has a great influence on the vehicle's movement behavior (or the degree of freedom of movement of the vehicle), so that if the vehicle data of the current vehicle configuration is taken into account, the accuracy of the obtained expected value of the actuating quantity can be improved. However, it should be understood that using vehicle data when obtaining the expected value of the actuating quantity is not essential for the present invention.

[0021] In a preferred refinement, obtaining the expected value of the actuating quantity using the vehicle data includes: predicting the dynamic behavior of the vehicle using the vehicle data; and obtaining the expected value of the actuating quantity based on the predicted dynamic behavior of the vehicle. Predicting the dynamic behavior of the current vehicle configuration is preferably carried out based on a model. Thus, the behavior of the vehicle can be predicted. In a preferred design, the vehicle model used to predict the dynamic behavior of the vehicle is a single-track model of the vehicle.

[0022] Preferably, the degree of freedom of movement is or includes the vehicle's longitudinal acceleration, the vehicle's longitudinal deceleration, the maximum curvature of the maximum drivable path of the vehicle, the vehicle's steering angular velocity, the vehicle's steering angle, the vehicle's braking distance, or the vehicle's yaw rate. Preferably, the degree of freedom of movement may also be or include the yaw ratio and / or the yaw rate.

[0023] The vehicle actuator is preferably or includes an active steering unit, a braking system, a parking brake, a continuous brake, a service brake, a wheel locking mechanism, an auxiliary steering unit, the internal combustion engine of the vehicle, and / or an electric motor. However, it may also be provided that the method is carried out for a plurality of vehicle actuators of the vehicle, for example, for the service brake and the active steering unit simultaneously.

[0024] According to a preferred embodiment, the performance difference is determined completely or at least partially by the braking system of the vehicle. This is particularly advantageous when the vehicle actuator is the braking system or a brake of the vehicle. However, it can also be provided that the braking system determines the performance difference of a vehicle actuator (such as a steering unit) that is not assigned to the braking system. Preferably, the determination of the performance difference is carried out completely or partially by the brake control unit of the braking system.

[0025] Preferably, the method further includes: providing a warning signal in the case where the performance difference of the vehicle brake is determined. The warning signal is preferably provided by means of a human-machine interface. The warning signal is preferably a visual, audible, tactile, and / or electronic warning signal. For example, the electronic warning signal can be provided to the autonomous unit of the vehicle, in particular the virtual driver. The human-machine interface is preferably a warning light, a speaker, and / or a screen.

[0026] In a preferred design, the target value of the degree of freedom of movement is determined based on data of the vehicle itself. The data of the vehicle itself are data determined by a vehicle system or unit of the vehicle, where this determination is not the reception of external data. For example, external data are data transmitted to the vehicle by means of a transmitting antenna and received by the antenna of the vehicle. By using the data of the vehicle itself when determining the target value of the degree of freedom of movement, this determination can be carried out independently of external units that do not belong to the vehicle. Preferably, the data of the vehicle itself are provided by a vehicle subsystem of the vehicle. For example, the signal of the brake control unit of the vehicle can be such data of the vehicle itself. The data of the vehicle itself preferably relate to the vehicle itself. The data of the vehicle itself are particularly preferably not route data and / or map data and / or digital maps.

[0027] In a second aspect, the present invention solves the task described at the beginning by means of an actuator monitoring system for monitoring performance characteristic parameters of a vehicle actuator, the vehicle actuator being configured to influence at least one degree of freedom of movement of the vehicle, the actuator monitoring system having: a status signal receiving unit, which can be connected to a vehicle network for receiving status signals representing the actual values of the degrees of freedom of movement of the vehicle, and which can be connected to the vehicle actuator for receiving the actual value of the control variable; a target value acquisition unit for the degree of freedom of movement, which is configured to acquire the target value of the degree of freedom of movement of the vehicle and the expected value of the control variable of the vehicle actuator for achieving the target value of the degree of freedom of movement; and a performance difference acquisition unit, which is configured to acquire a performance difference of the vehicle actuator in the following cases: the actual value of the degree of freedom of movement lies outside the tolerance of the degree of freedom of movement around the target value of the degree of freedom of movement and the actual value of the control variable is less than the maximum value of the control variable; the actual value of the degree of freedom of movement lies outside the tolerance of the degree of freedom of movement around the target value of the degree of freedom of movement, the expected value of the control variable corresponds to the maximum value of the control variable and the actual value of the control variable corresponds to the maximum value of the control variable; or the actual value of the degree of freedom of movement corresponds to the target value of the degree of freedom of movement, and the actual value of the control variable required to achieve the actual value of the degree of freedom of movement lies outside the tolerance of the control variable around the expected value of the control variable. In addition, the performance difference acquisition unit is preferably configured to acquire an updated maximum value of the degree of freedom of movement of the vehicle based on the acquired performance difference.

[0028] Preferably, the status signal receiving unit, the target value acquisition unit for the degree of freedom of movement and / or the performance difference acquisition unit are configured as components of a control unit. In a preferred design, the control unit of the actuator monitoring system is the brake control unit of the vehicle's braking system. Preferably, the actuator monitoring system also has an interface for outputting a warning signal, wherein the control unit is configured to output a warning signal via the interface in the case of a performance difference of the vehicle actuator being acquired. The interface can also be connected to a vehicle control unit configured to control the vehicle actuator for receiving the actual value of the control variable.

[0029] It should be understood that the actuator monitoring system according to the second aspect of the present invention can have the same and similar sub-aspects as those especially recorded in the dependent claims of the method according to the first aspect of the present invention. Thus, for example, the performance difference acquisition unit can be configured to acquire a performance difference only if the actual value of the degree of freedom of movement has been outside the tolerance of the degree of freedom of movement around the target value of the degree of freedom of movement for at least a difference time, or if the actual value of the control variable required to reach the target value of the degree of freedom of movement has been outside the tolerance of the control variable around the expected value of the control variable for at least a difference time.

[0030] Preferably, the present invention uses an actuator monitoring system to solve the task described at the beginning. The actuator monitoring system is configured to implement the method according to the first aspect of the present invention. Preferably, the actuator monitoring system includes a control unit that can be connected to the vehicle network to receive status signals representing the actual values of the vehicle's degrees of freedom of movement, and the control unit can be connected to the vehicle actuators to receive the actual values of the manipulated variables, wherein the control unit is configured to implement the method according to the first aspect of the present invention.

[0031] In a third aspect, the task described at the beginning is solved by a vehicle having one or more vehicle actuators, at least one network, and an actuator monitoring system according to the second aspect of the present invention. Preferably, the vehicle is a commercial vehicle. A commercial vehicle (Nfz), also known as a commercial motor vehicle (Nkw), is a motor vehicle that is determined, based on its construction type and equipment, for transporting people or goods, or for towing trailers, but is not a passenger vehicle or a motorcycle, but rather, for example, a bus, a truck, a tractor, or a crane truck. Within the scope of the present disclosure, a commercial vehicle can be a simple commercial vehicle (which is usually referred to in English as a rigid vehicle), or it can also be a vehicle train consisting of a towing vehicle and one or more trailer vehicles. Typical examples of vehicle trains include a saddle tractor and a semi-trailer.

[0032] Preferably, the vehicle has a braking system. Particularly preferably, the braking system is a pneumatic braking system. The braking system preferably includes one or more spring-loaded brakes, a trailer control module, and / or an electronic handbrake.

[0033] It should be understood that the vehicle according to the third aspect of the present invention can have the same and similar sub-aspects as those recorded especially in the dependent claims of the method according to the first aspect of the present invention.

[0034] The embodiments of the present invention will be described below with reference to the accompanying drawings. These drawings do not necessarily show the embodiments to scale. Instead, the drawings for illustration are implemented in a schematic and / or slightly distorted form. For supplementary content directly obtainable from the drawings, reference is made to the relevant prior art. It is to be considered here that various modifications and changes can be made to the form and details of the embodiments without departing from the general concept of the present invention. The features of the present invention disclosed in the description, the drawings, and the claims, whether individually or in any combination, are of significance for the improvement of the present invention. In addition, all combinations of at least two features disclosed in the description, the drawings, and / or the claims fall within the scope of the present invention. The general concept of the present invention is not limited to the exact form or details of the preferred embodiments shown and described below, nor to the subject matter restricted compared to the subject matter claimed in the claims. In terms of the set measurement range, the values within the mentioned boundary ranges should also be disclosed as boundary values and can be used arbitrarily and are protected by rights. For the sake of clear visibility, the same reference numerals are used below for the same or similar parts or parts with the same or similar functions. Description of the Drawings

[0035] Further advantages, features, and details of the present invention can be derived from the following description of the preferred embodiments and based on the drawings; wherein:

[0036] Figure 1 A top view of a schematically shown vehicle is illustrated;

[0037] Figure 2a A schematic flowchart of a first embodiment of a method for obtaining performance differences is illustrated;

[0038] Figure 2b A schematic flowchart of a second embodiment of a method for obtaining performance differences is illustrated;

[0039] Figure 2c A schematic flowchart of a third embodiment of a method for obtaining performance differences is illustrated;

[0040] Figure 3 A detailed flowchart of a method for obtaining the target value of the degrees of freedom of movement is illustrated; and

[0041] Figure 4 A detailed flowchart of a method for obtaining the expected value of the manipulation quantity is illustrated. Detailed Embodiments

[0042] Figure 1FIG. 0 shows a vehicle 300 having a plurality of vehicle actuators 302. The vehicle actuators 302 are configured to influence the vehicle 300 in terms of its longitudinal dynamics and lateral dynamics. To this end, the vehicle actuators 302 affect a plurality of degrees of freedom of movement DoF of the vehicle 300. To decelerate the vehicle 300, the braking system 304 of the vehicle 300 includes a plurality of brake cylinders 306, which are assigned to the wheels 308 of the vehicle 300. In the present embodiment, the brake cylinders 306 cooperate to decelerate the vehicle 300. The braking system 304 thus forms a first vehicle actuator 302. However, it may also be provided that the individual brake cylinders 306 form the vehicle actuator 302 individually and / or in subgroups.

[0043] To achieve the longitudinal deceleration DoF1 of the vehicle 300 (i.e., the first degree of freedom of movement DoF of the vehicle 300), the brake modulator 310 of the braking system 304 supplies a braking pressure pB to the brake cylinders 306. The brake cylinders 306 are then pressed and a braking slip is adjusted for the wheels 308 of the vehicle 300, which braking slip causes the longitudinal deceleration DoF1. The longitudinal deceleration DoF1 is shown in Figure 1 by means of arrows of decreasing length. The level of the braking pressure pB adjusted for the different brake cylinders 306 by the brake modulator 310 of the braking system 304 is determined by the brake control unit 312 of the braking system 304, which drives the brake modulator 310. Thus, the brake control unit 312 can drive the brake modulator 310 such that the brake modulator adjusts a higher braking pressure pB for the brake cylinders 306a, 306b assigned to the front wheels 308a, 308b of the vehicle 300 than for the brake cylinders 306c, 306d assigned to the rear wheels 308c, 308d of the vehicle 300. However, it may also be provided that the braking pressure pB is adjusted uniquely for the wheels or identically for all wheels 308. One braking pressure pB or a plurality of braking pressures pB is / are here the actuating quantity St of the vehicle brake 302 formed by the braking system 304.

[0044] The brake control unit 312 of the braking system 304 is connected to an autonomous unit 314 of the vehicle 300, which may also be referred to as a virtual driver 314. The virtual driver 314 is arranged to autonomously control the vehicle 300 such that the vehicle 300 can operate without a human driver. The virtual driver 314 is configured to plan a driving trajectory T for the vehicle 300, which driving trajectory includes a planned path P of the vehicle 300 and a speed profile corresponding to the path P. The speed profile defines the associated speed for each point on the path P. However, it may also be provided that the speed profile defines the associated speed only for points spaced apart from one another on the path P.

[0045] The brake control unit 312 and the virtual driver 314 of the brake system 304 are connected via a vehicle network 316, which in this example is a CAN bus system of the vehicle 300. The virtual driver 314 is configured to plan a driving trajectory T and to perform a positioning control of the vehicle 300. In the illustrated embodiment, the virtual driver 314 is therefore also a positioning control unit of the vehicle 300. However, in other embodiments, it can also be provided that the positioning control unit is a unit different from the virtual driver 314 provided for planning the driving trajectory T. When the vehicle 300 moves along the path P, the virtual driver 314 drives the brake system 304 so as to guide the vehicle 300 to travel along the path P at a speed V corresponding to the speed profile as much as possible. For this purpose, the virtual driver 314 provides a brake control signal SB on the vehicle network 316, which is then received by the brake control unit 312. The brake control unit 312 then drives the brake modulator 310 or the brake cylinder 306 according to the brake control signal SB.

[0046] As a further vehicle actuator 302, the vehicle 300 also has an electronically controllable steering unit 318. The lateral acceleration DoF2 and / or the yaw rate DoF3 of the vehicle 300 can be influenced by the steering unit 318. The lateral acceleration DoF2 and the yaw rate DoF3 form further degrees of freedom of movement DoF of the vehicle 300. Figure 1 In FIG. 1 , the lateral acceleration DoF2 and the yaw rate DoF3 are illustrated with the aid of arrows which illustrate the vehicle's cornering.

[0047] The electronically controllable steering unit 318 has a steering control unit 320, which is connected to the virtual driver 314 via the vehicle network 316. The virtual driver 314, which is regarded as a positioning control unit, provides a steering control signal SL to the steering control unit 320 via the vehicle network 316 to guide the vehicle 300 to travel along the path P. The steering control unit 320 receives the steering control signal SL and thereby learns the corresponding manipulated variable St of the regulating motor 324 of the electronically controllable steering unit 318 connected to the steering shaft 322. The manipulated variable St is the regulating current St3 of the regulating motor 324 in this example. When the regulating current St3 is provided, the regulating motor 324 plays a role in rotating the steering shaft 322, which in turn causes the steering angle δ to be adjusted at the front wheels 308a, 308b. Due to the friction between the front wheels 308a, 308b and the roadway 326 on which the vehicle 300 is traveling, the front wheels 308a, 308 set at the steering angle δ build up a lateral guiding force that causes the vehicle 300 to rotate. The lateral acceleration DoF2 and the yaw rate DoF3 correspond to this rotation and speed V of the vehicle 300 .

[0048] In addition, the vehicle 300 further includes a motor 328 that drives the rear wheels 308c and 308d of the vehicle 300. The driving torque M provided by the motor 328 on the rear wheels 308c and 308d can cause the longitudinal acceleration DoF4 of the vehicle 300. Similar to the longitudinal deceleration DoF1, the longitudinal acceleration DoF4 is also shown by an arrow whose length changes in Figure 1 which the length of the arrow increases in the longitudinal acceleration DoF4, thereby indicating that the speed V of the vehicle 300 is increasing. The motor controller 330 of the motor 328 is also connected to the virtual driver 314 via the vehicle network 316. To accelerate the vehicle 300, the virtual driver 314 provides a motor control signal SM on the vehicle network 316, which is then received by the motor control unit 330. The motor control unit 330 provides a manipulated variable St corresponding to the motor control signal SM. For example, the manipulated variable is the fuel injection amount St2 injected into the cylinders of the motor 328.

[0049] During the travel of the vehicle 300 on the path P, the virtual driver 314 always selects, if possible, a motor control signal SM that makes the driving torque M correspond to the desired longitudinal acceleration DoF4 of the vehicle 300 in its function as a positioning control unit. Similarly, the virtual driver 314 attempts to keep the vehicle 300 on the path P by means of a steering signal SL provided to the electronically controllable steering unit 318 via the vehicle network 314. For this purpose, the steering unit 318 sets, if possible, the lateral acceleration DoF2 and / or the desired deflection ratio DoF4 of the vehicle 300 desired by the virtual driver 314. In a similar manner, the virtual driver 314 selects, as much as possible, a braking control signal SB that achieves the longitudinal deceleration DoF1 of the vehicle 300 corresponding to the travel trajectory T in its function as a positioning control unit. Before or directly during the movement of the vehicle 300, there are already pre-planned target values for the degrees of freedom of movement DoF (degrees of freedom of movement target values DoF-Soll), namely the longitudinal deceleration DoF1, the lateral acceleration DoF2, the deflection ratio DoF3, and the longitudinal acceleration DoF4, on the virtual driver 314. These target values are known to the virtual driver 314 within the scope of the planned travel trajectory T. In this embodiment, the longitudinal deceleration target value DoF1-Soll has a value of 8 m / s 2 .

[0050] However, it should be understood that fewer, more, and / or other degrees of freedom target values DoF-Soll may also be present on the virtual driver 314 or on the semi-autonomous unit of the vehicle 300. In the case of full or partial manual control of the vehicle 300 by a human driver, the degrees of freedom target value DoF-Soll required or desired by the driver can also be determined from the adjustment travel of the actuating element. Thus, for example, the longitudinal deceleration target value DoF1-Soll can be determined from the adjustment travel of the brake pedal of the vehicle 300 and the corresponding pedal characteristic curve.

[0051] The virtual driver 314 requests the brake system 304, the steering unit 318, and the motor 328 to perform driving dynamic interventions by means of the brake control signal SB, the steering control signal SL, and the motor control signal SM provided on the vehicle network 316, and these driving dynamic interventions result in the degrees of freedom target value DoF-Soll. Thus, according to this embodiment, the brake control unit 312 of the brake system 304 receives a longitudinal deceleration target value DoF1-Soll of 8 m / s 2 as the brake control signal SB. Thereby, the brake control unit 312 determines the brake pressure expected value St1-EW, which is here the manipulated variable expected value St-EW for the brake pressure pB manipulated variable of the brake system 304. The brake pressure expected value St1-EW is the brake pressure pB that the brake control unit 312 expects to be required to achieve the longitudinal deceleration target value DoF1-Soll of 8 m / s 2 . In this embodiment, the determination of the brake pressure expected value St1-EW is based on a comprehensive characteristic curve. Here, the brake control unit 312 determines that the brake pressure expected value St1-EW corresponding to the longitudinal deceleration target value DoF1-Soll of 8 m / s 2 is 8 bar.

[0052] In the best case, the actual vehicle behavior of the vehicle 300 corresponds to the desired target vehicle behavior, where the manipulated variable expected value St-EW is adjusted as the manipulated variable actual value St-Ist of the vehicle actuator 302, resulting in the degrees of freedom actual value DoF-Ist, which corresponds to the desired degrees of freedom target value DoF-Soll. Thus, in this embodiment, in the ideal case, the brake pressure expected value St1-EW of 8 bar is adjusted as the brake pressure actual value St1-EW, resulting in a longitudinal deceleration of 8 m / s for the vehicle 300 2 (longitudinal deceleration actual value DoF1-Ist = 8 m / s 2). Thus, in an ideal situation, the vehicle 300 performs as expected by the virtual driver 314 and the brake control unit 312. However, for various reasons, there may be a situation where the actual value of the adjusted degree of freedom of movement DoF-Ist does not match the target value of the degree of freedom of movement DoF-Soll.

[0053] Therefore, for example, the performance of the vehicle actuator 302 that is set to affect the degree of freedom of movement DoF may be restricted. In this case, regulating the expected value of the actuating quantity St-EW as the actual value of the actuating quantity DoF-Ist does not result in the actual value of the degree of freedom of movement DoF-Ist, or there is a deviation between the actual value of the degree of freedom of movement DoF-Ist and the target value of the degree of freedom of movement DoF-Soll. Therefore, in the considered embodiment, regulating the expected value of the braking pressure St1-EW to 8 bar as the actual value of the braking pressure St1-Ist may not be sufficient to adjust the vehicle 300 to an 8 m / s 2 desired longitudinal deceleration DoF1. For example, due to rust formed on the brake disc corresponding to the brake cylinder 306 in the range of long-term disuse, it may be necessary to regulate the actual braking pressure value St1-Ist to 10 bar in order to achieve a longitudinal deceleration target value DoF1-Soll of 3 m / s 2 In this case, there will be a performance difference 3 of the vehicle brake 302 of the braking system 304. Here, this performance difference is not necessarily understood as physical power in watts, but refers to the ability to complete the preset task.

[0054] The above-mentioned performance difference 3 of the braking system 304 caused by rust formed during long-term disuse is a safety hazard. If the human driver and / or the virtual driver 314 of the vehicle 300 are not aware of the performance difference 3, it may lead to an accident. Therefore, the reduced performance of the braking system 304 may, for example, result in an extended braking distance of the vehicle 300, which may trigger an accident. In order to identify the performance difference 3 of the vehicle actuator 302, the vehicle 300 has an actuator monitoring system 200. The actuator monitoring system 200 is configured to implement the method 1 for obtaining the performance difference 3 between the target performance and the actual performance of the vehicle actuator 302, which will be explained below with reference to FIGS. 2 to Figure 4 as explained to obtain the performance difference 3 between the target performance and the actual performance of the vehicle actuator 302.

[0055] In the first step of Method 1, the 9 - degree - of - freedom target value DoF - Soll is determined. This has been described above in connection with determining the longitudinal deceleration target value DoF1 - Soll when using the driving trajectory T. Immediately after determining the 9 - longitudinal deceleration target value DoF1 - Soll, as the second step of Method 1, the 11 - control variable expected value St - EW is determined. This has also been explained above as determining the brake pressure expected value St1 - EW of the brake system 304. However, it should be understood that in order to achieve the degree - of - freedom target value DoF - Soll, the 11 - control variable expected values St - EW of different vehicle actuators 302 can also be determined. As a further step, Method 1 includes determining the 13 - actual degree - of - freedom value DoF - Ist of the vehicle 200 corresponding to the degree - of - freedom target value DoF - Soll. Thus, for the example of the longitudinal deceleration target value DoF1 - Soll described here, the 13 - actual longitudinal deceleration value DoF1 - Ist of the vehicle 300 in the driving situation is determined when determining the 13. The 15 - actual control variable value St - Ist is determined to find out which control variable St is actually provided on the vehicle actuator 302 in order to adjust the actual degree - of - freedom value DoF - Ist. Thus, in the example of the longitudinal deceleration DoF1 of the considered vehicle 300, for example, it is determined which brake pressure pB is provided on the brake cylinder 306 of the vehicle 300 as the actual control variable value St - Ist (or St1 - Ist) in order to adjust the actual longitudinal deceleration value DoF1 - Ist as the actual degree - of - freedom value DoF - Ist.

[0056] In a further step of Method 1, the 17 - maximum control variable value St - Max of the vehicle brake 208 is obtained. For the brake system 304, the maximum control variable value St - Max is the maximum brake pressure that can be provided on the brake cylinder 306. For the sake of simplicity, in this example, the same brake pressure pB is considered for all brake cylinders 306 of the vehicle 300. However, it should be understood that each brake cylinder 306 can also be considered individually.

[0057] In this embodiment, steps 9, 11, 13, 15, 17 are partially carried out simultaneously. However, it can also be arranged that individual ones of these steps are carried out earlier or later than other steps. Thus, before determining the 9 - degree - of - freedom target value DoF - Soll, the 17 - maximum control variable value St - Max can also be determined. In addition, the actual control variable value St - Ist can also be determined continuously, for example (determining the 15 can be carried out continuously), so that determining the 15 can also be carried out partially before determining the 13 - actual degree - of - freedom value DoF - Ist.

[0058] The actual value of the degree of freedom of movement (DoF-Ist) is obtained here by the status signal receiving unit 206 of the actuator monitoring system 200. For this purpose, the status signal receiving unit 206 receives the corresponding status signal SZ from the vehicle network 316, where the status signal SZ representing the actual value of the degree of freedom of movement DoF-Ist is provided by the virtual driver 314 on the vehicle network 316 in the considered embodiment. The virtual driver 314 determines the actual value of the longitudinal deceleration DoF1-Ist with the aid of various sensors (not shown) in Figure 1 . However, it can also be provided, for example, that the actual value of the longitudinal deceleration DoF1-Ist is determined by a conventional stability control system, which is also known in English as Electronic Stability Control (ESC). In this case, the ESC then provides the status signal SZ on the vehicle network 316. In addition, it can be provided that the status signal receiving unit 206 directly determines the actual value of the degree of freedom of movement DoF-Ist by measurement. In addition, the status signal receiving unit 206 also receives the actual value of the actuating variable St-Ist via the vehicle network 316. Thus, in the considered embodiment of the longitudinal deceleration DoF1, the brake control unit 312 continuously provides the actual value of the actuating variable St1-EW or the corresponding signal on the vehicle network 316.

[0059] The target value acquisition unit 208 for the degree of freedom of movement of the actuator monitoring system 200 acquires the target value DoF-Soll for the degree of freedom of movement. For this purpose, the target value acquisition unit 208 for the degree of freedom of movement receives the driving trajectory T provided by the virtual driver 314 on the vehicle network 316 and determines one or more target values DoF-Soll for the degree of freedom of movement therefrom. However, it can also be provided that the virtual driver 314 is part of the actuator monitoring system 200, in particular the target value acquisition unit 208 for the degree of freedom of movement. In addition, the target value acquisition unit 208 for the degree of freedom of movement also determines the expected value St-EW of the actuating variable on the basis of the signals of the vehicle network 316. In the considered embodiment, this is achieved by evaluating the signals of the brake control unit 312.

[0060] In addition, the actuator monitoring system 200 also includes a performance difference acquisition unit 210, which acquires the performance difference 3 of the considered vehicle actuator 302. Here, the status signal receiving unit 206, the target value acquisition unit 208 for the degree of freedom of movement and the performance difference acquisition unit 310 are subunits of the monitoring control unit 202 of the actuator monitoring system 200, but can also be implemented as separate units. Thus, the target value acquisition unit 208 for the degree of freedom of movement can also be formed, for example, by the virtual driver 314. In addition, the monitoring control unit 202 also includes an interface 204 connected to the vehicle network 316.

[0061] After knowing 9 the target value of the degree of freedom of motion DoF-Soll, knowing 11 the expected value of the manipulated variable St-EW11, knowing 13 the actual value of the degree of freedom of motion DoF-Ist, knowing 15 the actual value of the manipulated variable St-Ist and obtaining 17 the maximum value of the manipulated variable St-Max, then, if the following reference is met Figures 2a to 2c If one of the three conditions is satisfied, then in method 1 the determination 19 of the performance difference 3 of vehicle actuator 302 is performed.

[0062] In the first case, if the actual value of the degree of freedom of movement DoF is equal to the target value of the degree of freedom of movement DoF, but the actual value of the manipulated variable St-Ist required to adjust the actual value of the degree of freedom of movement DoF-Ist is greater than the previously known expected value of the manipulated variable St-EW, the performance difference detection unit 210 of the actuator monitoring system 200 detects the performance difference 3. In the embodiment of the longitudinal deceleration DoF1 of the vehicle 300 currently considered, in this case, it can therefore reach 8 m / s 2 The longitudinal deceleration target value DoF1-Soll is obtained, but for this purpose a brake pressure St1-Ist of 10 bar must be provided at the brake cylinder 206 of the brake system 304 instead of the brake pressure expected value St1-EW of 8 bar. Figure 2a In the first case shown, in which the performance difference 3 is determined 19, the desired vehicle movement can therefore be achieved, but for this purpose the vehicle brake 304 must be actuated more strongly than expected. This can occur, for example, if the brake lining associated with the brake cylinder 306 overheats. The virtual driver 314, which acts as a positioning control unit, detects small deviations between the desired value for the degree of freedom of movement DoF-Soll and the actual value for the degree of freedom of movement DoF-Ist and accordingly fine-tunes the brake control signal SB or the brake pressure pB with the aid of the brake control unit 312, so that overall the longitudinal deceleration desired value DoF1-Soll is achieved as the actual value for the longitudinal deceleration DoF1-Ist.

[0063] However, in order to prevent erroneous acquisition, the performance difference 3 is acquired 19 only when the actual value of the manipulated variable St-Ist is outside the manipulated variable tolerance ΔSt around the expected value of the manipulated variable St-EW. This prevents, for example, a small measurement inaccuracy that occurs when acquiring the actual value of the manipulated variable St-Ist from leading to the acquisition 19 of the performance difference 3.

[0064] Figure 2a The performance difference 3 shown in the determination 19 is a situation that frequently occurs in practice, in which the operating capacity of one or more vehicle actuators 302 is undesirably reduced, although the desired vehicle behavior can be controlled. Figure 2b and Figure 2cshows a situation where it is not possible to adjust the vehicle behavior or the actual value of the degree of freedom of movement DoF-Ist of the vehicle 300 deviates from the target value of the degree of freedom of movement DoF-Soll. In the considered embodiment, when a maximum longitudinal deceleration actual value DoF1-Ist of only 4 m / s 2 is achieved, instead of the target value of the longitudinal deceleration DoF1-Soll of 8 m / s 2 . This deviation between the target value of the longitudinal deceleration DoF1-Soll and the actual value of the longitudinal deceleration DoF1-Ist can be caused by different reasons.

[0065] In the second case of knowing the performance difference 3 ( Figure 2b ), there is a deviation between the actual value of the degree of freedom of movement DoF-Ist and the target value of the degree of freedom of movement DoF-Soll, and the actual value of the control variable is less than the maximum value of the control variable St-Max. Therefore, the value achieved for the considered longitudinal deceleration DoF1 is 4 m / s 2 , instead of the target value of the longitudinal deceleration DoF1-Soll of the desired 8 m / s 2 , and the braking pressure pB is below the maximum braking pressure pB_max of 10 bar. If the vehicle 300 decelerates less strongly than desired (DoF1-Ist ≤ DoF1-Soll), the virtual driver 314 and also the human driver will demand additional braking performance from the braking system 304. However, for various reasons, this may not be achievable, for example, if due to a leak occurring at the braking system 304, only a braking pressure pB of 8 bar can be adjusted, instead of the maximum braking pressure of 10 bar according to the configuration. Therefore, if there is a performance difference 3 of the vehicle brake 302, the target value of the degree of freedom of movement DoF-Soll will deviate from the actual value of the degree of freedom of movement DoF-Ist, and thus the performance difference 3 can be known. To compensate for measurement inaccuracies, in the second case, the performance difference 19 is only known when the deviation between the actual value of the degree of freedom of movement DoF-Ist and the target value of the degree of freedom of movement DoF-Soll exceeds the tolerance of the degree of freedom of movement ΔDoF.

[0066] In the third case (see Figure 2c), if there is a deviation between the actual value of the degree of freedom of movement DoF-Ist and the target value of the degree of freedom of movement DoF-Soll, even if the actual value of St, St-Ist, is equal to the expected value of the actuating quantity St-EW and equal to the maximum value of the actuating quantity St-Max, the performance difference 3 is also ascertained. Thus, in the present embodiment, when the vehicle 300 is fully braked, although a maximum braking pressure pB of 10 bar is adjusted, the actual value of the longitudinal deceleration DoF1-Ist achieved is still lower than the target value of the longitudinal deceleration DoF1-Soll. For example, this situation occurs when the braking system 304 of the vehicle 300 can no longer provide full deceleration performance due to overheating of the brake discs and brake linings.

[0067] Apart from the ascertainment 19 or the conditions to be met therefor, according to Figures 2a to 2c the methods are the same, so that the following description analogously applies to all three cases of the ascertainment 19 of the performance difference 3. Similarly, in the methods 1 according to Figures 2a to 2c the ascertainments 9, 11, 13, 15 and the acquisitions 17 are also substantially the same. In the present embodiment, the ascertainment 9 of the target value of the degree of freedom of movement DoF-Soll is based on the driving trajectory T, where first the driving trajectory T of the vehicle 300 is ascertained by the virtual driver 314 ( Figure 3 the ascertainment 23 in Figure 3 ), and then the target value of the degree of freedom of movement DoF-Soll is ascertained based on the driving trajectory T, as described above (

[0068] the ascertainment 29 in 2 ). By taking into account the target value of the degree of freedom of movement DoF-Soll, the actual value of the degree of freedom of movement DoF-Ist, the expected value of the actuating quantity St-EW, the actual value of the actuating quantity St-Ist and the maximum value of the actuating quantity St-Max, the performance difference 3 of the vehicle actuator 304 can be ascertained in method 1 according to the invention. Immediately after the ascertainment 19 of the performance difference 3, in method 1 the updated maximum value of the degree of freedom of movement DoF-Max is also ascertained 21 based on the ascertained performance difference 3. Thus, the performance difference 3 is used to update the maximum value of the degree of freedom of movement DoF-Max of the vehicle 300. Thus, for example, when the braking system 304 is fully functional, the maximum longitudinal deceleration DoF1-Max of the vehicle 300 can have a value of 10 m / s 2 . However, due to rust on the brake discs assigned to the brake cylinders 306, a performance difference 3 of the braking system 3 may exist, so that in some cases the longitudinal deceleration DoF1 of the vehicle 300 can only reach 6 m / s

[0069] Therefore, in Figures 2a to 2c Method 1 shown includes obtaining the driving dynamic boundary value 33 of vehicle 300. The driving dynamic boundary value 33 is obtained based on the updated maximum degrees of freedom of motion DoF-Max. Thus, in the simplest case, the driving dynamic boundary value 33 can be the maximum longitudinal deceleration DoF1 that vehicle 300 can demand. However, here, the driving dynamic boundary value 33 is the maximum speed V_max that vehicle 300 may not exceed. Therefore, when the performance difference 3 of braking system 304 is obtained, for example, the maximum speed V_max of vehicle 300 can be limited to a value of 50 km / h. Particularly preferably, the driving dynamic boundary value 33 is scaled according to the obtained performance difference 3. Thus, for example, when braking system 304 can provide a longitudinal deceleration DoF1 of 6 m / s for vehicle 300 2 the maximum speed V_max may be 70 km / h; while when braking system 304 is capable of providing a longitudinal deceleration DoF1 of 3 m / s for vehicle 300 2 the maximum speed V_max may be only 30 km / h.

[0070] In addition, in the shown embodiment, Method 1 has: re-obtaining 35 the planned driving trajectory T in the case of using the obtained driving dynamic boundary value 33. For this purpose, the actuator monitoring system 200 provides the driving dynamic boundary value 33 on the vehicle network 316 via the interface 204. The virtual driver 314 receives the driving dynamic boundary value 33 and re-plans the driving trajectory T, where the driving trajectory T will comply with the obtained maximum speed V_max. However, in the case of re-obtaining 35 the driving trajectory T, the driving trajectory T can also be updated instead of completely re-obtaining. Thus, for example, the path P can be retained and only the associated speed profile is adjusted.

[0071] In addition, in the shown embodiment, Method 1 further includes: providing 61 a warning signal 63 if the performance difference 3 of vehicle actuator 304 is obtained. Here, the warning signal 63 is a digital signal provided by the actuator monitoring system 200 on the vehicle network 316 via the interface 204. In addition, the warning signal 63 also includes visual and audible warning signals 63 provided on the human-machine interface 332 in the cockpit of vehicle 300 not shown in the figure. Thus, it is possible to prompt the human passenger of the performance difference and enable the human passenger to take over the control of vehicle 300 from the virtual driver 314 when necessary.

[0072] As described above, method 1 preferably uses only the vehicle's own data to obtain 11, 15 the expected value St-EW of the manipulated variable and the actual value St-Ist of the manipulated variable. The target value DoF-Soll of the degree of freedom of motion and / or the actual value DoF-Ist of the degree of freedom of motion can also be obtained based only on the vehicle's own data. Therefore, the actual value of the longitudinal deceleration DoF1-Ist can be obtained, for example, with the aid of an acceleration sensor without the need for GPS data. Obtaining 9 the target value DoF-Soll of the degree of freedom of motion can also be performed without external data or using only the vehicle's own data. The virtual driver 314 then preferably does not use external map data to obtain the driving trajectory T. However, it can also be provided that one of the steps 9, 11, 13, 15 of obtaining is performed using data outside the vehicle but without using external map data.

[0073] Figure 4 The determination 11 of the expected value St-EW of the manipulated variable of the vehicle actuator 302 is further shown in detail. In the present embodiment, the determination 11 is performed by determining the environmental data 39 of the vehicle 200. When determining 41 the expected value St-EW of the manipulated variable, these environmental data 39, such as weather data or slope information, are taken into account. Therefore, in method 1, it can be taken into account that due to the downhill road, a greater braking pressure pB must be adjusted than on a flat road. In addition, the determination 11 of the expected value St-EW of the manipulated variable includes the determination 47 of the expected value St-EW of the manipulated variable, which is determined using the ( Figure 4 The process is performed under the condition of acquiring 43 the vehicle data 45. Therefore, in the illustrated embodiment, both the environmental data 39 and the vehicle data 45 are used to acquire 11 the desired manipulated variable value St-EW.

[0074] The determination 47 of the expected manipulated variable value St-EW using the vehicle data 45 is used to take the current condition of the vehicle 300 into account. Therefore, the vehicle data 45 of the current vehicle configuration 301 preferably also include load information about the loading of the vehicle. Therefore, due to the overloading of the vehicle 300, the deceleration performance of the vehicle 300 may also be impaired (or there may be a performance difference 3 of the brake system 304 as a result). When the expected manipulated variable value St-EW is determined 47 using the vehicle data 45, in the illustrated embodiment, the dynamic behavior of the vehicle 300 in the current vehicle configuration 31 is first predicted ( Figure 4 49), and then based on the predicted dynamic behavior of the vehicle 300, the expected value of the manipulated variable St-EW ( Figure 4 51 in the knowledge). Therefore, the prediction 49 can be performed, for example, using a vehicle model, in particular a single track model of the vehicle 300. This improves the accuracy of the method 1.

[0075] It should be understood that the method 1 for obtaining the performance difference 3 of the vehicle actuator 302 different from the braking system 304 can be carried out in a substantially similar manner. In particular, the performance differences 3 of different vehicle actuators 302 can also be carried out simultaneously. In this case, some of the obtaining steps may also coincide.

[0076] List of reference numerals (part of the specification)

[0077] 1 Method

[0078] 3 Performance difference

[0079] 9 Obtaining the target value of the degree of freedom of movement

[0080] 11 Obtaining the expected value of the manipulated variable

[0081] 13 Obtaining the actual value of the degree of freedom of movement

[0082] 15 Obtaining the actual value of the manipulated variable

[0083] 17 Obtaining the maximum value of the manipulated variable

[0084] 19 Obtaining the performance difference

[0085] 21 Obtaining the updated maximum value of the degree of freedom of movement

[0086] 23 Obtaining the planned driving trajectory

[0087] 29 Obtaining the target value of the degree of freedom of movement based on the trajectory

[0088] 31 Obtaining the driving dynamic boundary value

[0089] 33 Driving dynamic boundary value

[0090] 35 Re-obtaining the trajectory

[0091] 37 Obtaining the environmental data

[0092] 39 Environmental data

[0093] 41 Obtaining the expected value of the manipulated variable in the case of using the environmental data

[0094] 43 Obtaining the vehicle data

[0095] 45 Vehicle data

[0096] 47 Obtaining the expected value of the manipulated variable in the case of using the vehicle data

[0097] 49 Predicting the dynamic driving behavior

[0098] 51 Obtaining the expected value of the manipulated variable based on the predicted dynamic characteristics

[0099] 61 Providing a warning signal

[0100] 63 Warning signal

[0101] 200 Actuator monitoring system

[0102] 202 Monitoring control unit

[0103] 204 Interface

[0104] 206 Status signal receiving unit

[0105] 208 Target value acquisition unit for degrees of freedom of motion

[0106] 210 Performance difference acquisition unit

[0107] 300 Vehicle

[0108] 301 Current vehicle configuration

[0109] 302 Vehicle actuator

[0110] 304 Brake system

[0111] 306, 306a, 306b, 306c, 306d Brake cylinder

[0112] 308 Wheel

[0113] 308a, 308b Front wheel

[0114] 308c, 308d Rear wheel

[0115] 310 Brake modulator

[0116] 312 Brake control unit

[0117] 314 Autonomous unit; Virtual driver

[0118] 316 Vehicle network

[0119] 318 Electronically controllable steering section

[0120] 320 Steering control unit

[0121] 322 Steering shaft

[0122] 324 Adjusting motor

[0123] 326 Driving lane

[0124] 328 Motor

[0125] 330 Motor control unit

[0126] 332 Human-machine interface

[0127] DoF Degrees of freedom of motion

[0128] DoF1 Longitudinal deceleration

[0129] DoF2 Lateral acceleration

[0130] DoF3 Deflection ratio

[0131] DoF4 Longitudinal acceleration

[0132] DoF-Ist Actual value of the degree of freedom of movement

[0133] DoF1-Ist Actual value of the actual longitudinal deceleration

[0134] DoF-Max Maximum value of the degree of freedom of movement

[0135] DoF-Soll Target value of the degree of freedom of movement

[0136] DoF1-Soll Target value of the longitudinal deceleration

[0137] ΔDoF Tolerance of the degree of freedom of movement

[0138] M Driving torque

[0139] P Path

[0140] SB Braking control signal

[0141] SL Steering control signal

[0142] SM Motor control signal

[0143] St-EW Expected value of the control quantity

[0144] St1-EW Expected value of the braking pressure

[0145] St-Ist Actual value of the control quantity

[0146] St1-Ist Actual value of the braking pressure

[0147] St2 Injection quantity

[0148] St3 Adjusting current

[0149] ΔSt Tolerance of the control quantity

[0150] SZ Status signal

[0151] T Trajectory

[0152] V Velocity

[0153] V_max Maximum velocity

[0154] δ Steering angle

Claims

1. A method (1) for obtaining a performance difference (3) between a target performance and an actual performance of a vehicle actuator (302) of a vehicle (300), wherein, The vehicle actuator (302) is configured to influence at least one degree of freedom of movement (DoF) of the vehicle (200), wherein the method (1) comprises: - ascertaining (9) a target value of the degree of freedom of movement (DoF-Soll) of the vehicle; - ascertaining (11) an expected value of the actuating variable (St-EW) for achieving the target value of the degree of freedom of movement (DoF-Soll); - ascertaining (13) an actual value of the degree of freedom of movement (DoF-Ist) of the vehicle (300) corresponding to the target value of the degree of freedom of movement (DoF-Soll); - ascertaining (15) an actual value of the actuating variable (St-Ist) provided to the vehicle actuator (302) for achieving the actual value of the degree of freedom of movement (DoF-Ist); - obtaining (17) a maximum value of the actuating variable (St-Max) of the vehicle actuator (302); and - ascertaining (19) a performance difference (3) of the vehicle actuator (302) if: the actual value of the degree of freedom of movement (DoF-Ist) is outside a tolerance of the degree of freedom of movement (ΔDoF) around the target value of the degree of freedom of movement (DoF-Soll), and the actual value of the actuating variable (St-Ist) is less than the maximum value of the actuating variable (St-Max); the actual value of the degree of freedom of movement (DoF-Ist) is outside a tolerance of the degree of freedom of movement (ΔDoF) around the target value of the degree of freedom of movement (DoF-Soll), the expected value of the actuating variable (St-EW) corresponds to the maximum value of the actuating variable (St-Max), and the actual value of the actuating variable (St-Ist) corresponds to the maximum value of the actuating variable (St-Max), or the actual value of the degree of freedom of movement (DoF-Ist) corresponds to the target value of the degree of freedom of movement (DoF-Soll), and the actual value of the actuating variable (St-Ist) required to achieve the actual value of the degree of freedom of movement (DoF-Ist) is outside a tolerance of the actuating variable (ΔSt) around the expected value of the actuating variable (St-EW); and - ascertaining (21) an updated maximum value of the degree of freedom of movement (DoF-Max) of the vehicle (200) on the basis of the ascertained performance difference (3).

2. The method (1) according to claim 1, wherein, The performance difference (3) of the vehicle actuator (302) is only ascertained (19) if: the actual value of the degree of freedom of movement (DoF-Ist) has been outside a tolerance of the degree of freedom of movement (ΔDoF) around the target value of the degree of freedom of movement (DoF-Soll) for at least a difference time, or the actual value of the actuating variable (St-Ist) required to achieve the target value of the degree of freedom of movement (DoF-Soll) has been outside a tolerance of the actuating variable (ΔSt) around the expected value of the actuating variable (St-EW) for at least a difference time.

3. The method (1) according to claim 1 or 2, wherein Ascertaining (9) the target value of the degree of freedom of movement (DoF-Soll) comprises: - ascertaining (23) a planned travel trajectory (T) of the vehicle (200) by means of an autonomous unit (27); - The target value (DoF-Soll) of the degree of freedom of movement is obtained (29) based on the driving trajectory (T).

4. The method (1) according to any one of claims 1 to 3, the method further comprising: - In the case of obtaining the performance difference (3) of the vehicle actuator (302), the boundary value (33) of the driving dynamics of the vehicle (200) is obtained (31) using the obtained performance difference (3).

5. The method (1) according to claims 3 and 4, the method further comprising: - The planned driving trajectory (T) is re-obtained (35) using the obtained boundary value (33) of the driving dynamics.

6. The method (1) according to any one of claims 1 to 5, wherein The expected value (St-EW) of the actuation quantity for the vehicle actuator (302) to achieve the target value (DoF-Soll) of the degree of freedom of movement is obtained (11) using the actually measured value of the learned actuation quantity for the learned target value of the degree of freedom of movement, and the actually measured value of the learned actuation quantity is within the tolerance of the degree of freedom of movement around the target value of the degree of freedom of movement.

7. The method (1) according to any one of claims 1 to 6, wherein Obtaining (11) the expected value (St-EW) of the actuation quantity for the vehicle actuator (302) to achieve the target value (DoF-Soll) of the degree of freedom of movement includes: - Obtaining (37) the environmental data (39) of the vehicle (200), and - Obtaining (41) the expected value (St-EW) of the actuation quantity using the environmental data (39).

8. The method (1) according to any one of claims 1 to 7, wherein, Obtaining (11) the expected value (St-EW) of the actuation quantity for the vehicle actuator (302) to achieve the target value (DoF-Soll) of the degree of freedom of movement includes: - Obtaining (43) the vehicle data (45) of the current vehicle configuration (202) of the vehicle (200), and - Obtaining (47) the expected value (St-EW) of the actuation quantity using the vehicle data (45).

9. The method (1) according to claim 8, wherein, Obtaining (47) the expected value (St-EW) of the actuation quantity using the vehicle data (45) includes: - Predicting (49) the dynamic behavior of the vehicle (200) using the vehicle data (45); and - Obtaining (51) the expected value (St-EW) of the actuation quantity based on the predicted dynamic behavior of the vehicle (200).

10. The method (1) according to any one of claims 1 to 9, wherein, The degree of freedom of movement (DoF) is or the degree of freedom of movement includes: the longitudinal acceleration (DoF4) of the vehicle (300), the longitudinal deceleration (DoF1) of the vehicle (200), the maximum curvature of the maximum drivable path of the vehicle (300), the steering angular velocity of the vehicle (300), the steering angle (δ) of the vehicle (300) or the deflection speed of the vehicle (300).

11. The method (1) according to any one of claims 1 to 10, wherein, The vehicle actuator (302) includes: the active steering part of the vehicle (200), the braking system, the parking brake, the continuous brake, the service brake, the wheel locking mechanism, the auxiliary steering part, the internal combustion engine and / or the electric motor.

12. The method (1) according to any one of claims 1 to 11, wherein It is learned that the performance difference (3) is performed by the braking system (304) of the vehicle (300).

13. The method (1) according to any one of claims 1 to 12, the method further comprising: - providing (61) a warning signal (63) in the case where a performance difference (3) of the vehicle actuator (302) is learned, wherein the warning signal (63) is preferably provided by means of a human-machine interface (332).

14. The method (1) according to any one of claims 1 to 13, wherein The target value of the degree of freedom of movement (DoF-Soll) is learned based on data of the vehicle itself.

15. An actuator monitoring system (100) for monitoring performance characteristic parameters of a vehicle actuator (302), the vehicle actuator being configured to affect at least one degree of freedom of movement (DoF) of a vehicle (300), the actuator monitoring system (200) having: a status signal receiving unit (206) that can be connected to a network (316) of the vehicle (300) to receive a status signal (SZ) representing the actual value of the degree of freedom of movement (DoF-Ist) of the vehicle (300), and the status signal receiving unit can be connected to the vehicle actuator (302) to receive the actual value of the manipulated variable (St-Ist), a degree-of-freedom-of-movement target value learning unit (208) configured to learn the target value of the degree of freedom of movement (DoF-Soll) of the vehicle (300) and the expected value of the manipulated variable (St-EW) of the vehicle actuator (302) for achieving the target value of the degree of freedom of movement (DoF-Soll), a performance difference learning unit (210) configured to learn the performance difference (3) of the vehicle actuator (302) in the following cases: the actual value of the degree of freedom of movement (DoF-Ist) is outside the tolerance of the degree of freedom of movement (ΔDoF) around the target value of the degree of freedom of movement (DoF-Soll), and the actual value of the manipulated variable (St-Ist) is less than the maximum value of the manipulated variable (St-Max); the actual value of the degree of freedom of movement (DoF-Ist) is outside the tolerance of the degree of freedom of movement (ΔDoF) around the target value of the degree of freedom of movement (DoF-Soll), the expected value of the manipulated variable (St-EW) is equal to the maximum value of the manipulated variable (St-Max), and the actual value of the manipulated variable (St-Ist) is equal to the maximum value of the manipulated variable (St-Max), or The actual value of the degree of freedom of movement (DoF-Ist) corresponds to the target value of the degree of freedom of movement (DoF-Soll), and the actual value of the actuation quantity (St-Ist) required to achieve the actual value of the degree of freedom of movement (DoF-Ist) lies outside the actuation quantity tolerance (ΔSt) around the expected value of the actuation quantity (St-EW), and wherein, the performance difference learning unit (210) is configured to learn the updated maximum value of the degree of freedom of movement (DoF-Max) of the vehicle (200) based on the learned performance difference (3).

16. A vehicle (300) having one or more vehicle actuators (302), at least one network (316), and an actuator monitoring system (200) according to claim 15, the actuator monitoring system being connected to the network (316) for receiving actual value data representative of the actual values (DoF-Ist) of the degrees of freedom of movement.

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