Load detection procedure

Abstract

Method for load detection in a vehicle (1) which has a chassis (3) with a plurality of vehicle wheels (10, 11, 12, 13) which stand or roll on a ground (26), and a vehicle body (2) carried by the chassis (3) which is resiliently supported on unsprung components of the chassis (3) which comprise the vehicle wheels (10, 11, 12, 13), each of which is assigned a wheel stroke (h) characterizing its respective distance from the vehicle body (2) in a vehicle vertical direction (z), wherein - when the vehicle (1) is at a standstill, at least one or more of the wheel strokes are determined as static wheel stroke information (51), - a mass of the vehicle and / or the vehicle body is determined as a static mass (m_stat) from the static wheel stroke information (51) and from suspension information (52) characterising the suspension behaviour of the vehicle body (2), - at least one driving dynamics variable of the vehicle (1) is determined during a journey of the vehicle (1), - on the basis of the at least one driving dynamic variable of the vehicle (1), a mass of the vehicle (1) and / or of the vehicle body is determined as a dynamic mass (m_dyn) and - the dynamic mass (m_dyn) is compared with the static mass (m_stat) and the suspension information (52) is formed or corrected depending thereon.

Description

The invention relates to a method for detecting loads in a vehicle, which has a chassis having a plurality of vehicle wheels which stand or roll on a ground, and a vehicle structure which is carried by the chassis and is resiliently supported on unsprung components of the chassis, which components comprise the vehicle wheels, each of which has associated therewith a wheel stroke characterizing their respective distance from the vehicle structure in a vehicle vertical direction, wherein, in a standstill of the vehicle, at least one or more of the wheel strokes are determined as static wheel stroke information, preferably by measurement, and a mass of the vehicle and / or of the vehicle structure is determined as a static mass from the static wheel stroke information and from a suspension information characterizing the suspension behavior of the vehicle structure, in particular with respect to the unsprung components, wherein, during a journey of the vehicle, at least one vehicle dynamic parameter is determined, and on the basis of the at least one driving dynamic variable of the vehicle, a mass of the vehicle and / or of the vehicle structure is determined as a dynamic mass, and the dynamic mass is compared with the static mass and the suspension information is formed or corrected as a function thereof, wherein the at least one driving dynamic variable of the vehicle comprises at least one variable of the longitudinal dynamics of the vehicle and at least one variable of the vertical dynamics of the vehicle.Such a method is known from DE 10 2022 201 560 A1. A comparable method for determining a mass of the vehicle is also known from DE 10 2006 045 305 B3.The suspension information comprises, for example, a characteristic curve or spring stiffness, so that the static mass can be determined from this and from the wheel stroke, for example using the Hooke's law and the second Newton's law taking into account the gravitational acceleration. If the mass of the unloaded vehicle and / or vehicle body is known, the mass of the load can also be determined from the static mass. It is problematic that the suspension information can change over time, for example due to seating processes and / or material fatigue.The prior art also discloses the determination of the load and / or mass of a vehicle during travel, which can be carried out with relatively high accuracy. For example, DE 10 2013 211 243 A1 discloses a method in which the vehicle mass of a moving motor vehicle is determined, wherein a speed signal, a longitudinal acceleration signal, a brake signal and a drive signal are considered, wherein a force balance of the longitudinal dynamics of the motor vehicle is evaluated and wherein the longitudinal acceleration signal is measured by an inertial sensor. An evaluation of the force balance of the longitudinal dynamics takes place both during acceleration and during braking processes, wherein a number of raw mass values is calculated and wherein the vehicle mass is determined on the basis of a statistical evaluation of the raw mass values, which comprises at least one averaging.Furthermore, EP 1 863 659 B1 describes a method for determining the mass of a vehicle or a wheel-specific mass proportion of a vehicle with a wheel suspension that enables vertical movements between the vehicle structure and the vehicle wheels, wherein the mass estimation is carried out by means of a state observer based on the vertical dynamics of the vehicle. The mass of the vehicle body and / or that of the so-called unsprung masses and / or the mass inertia of the body about the longitudinal axis of the vehicle and / or about the transverse axis of the vehicle is determined by means of a preferably nonlinear state observer, which evaluates the vertical dynamics of the vehicle. Excitations of the vehicle structure by acceleration and / or braking processes and / or steering maneuvers on the vehicle via modeling of the longitudinal dynamics and / or the lateral dynamics are preferably taken into account either via a physical model, in particular a single-lane or two-lane model, or via the measured longitudinal acceleration(s) and / or lateral acceleration / s.However, if the mass is determined exclusively during the trip and not before the start of the trip, several disadvantages can occur, since the trip is started with a possibly overcharged vehicle. For example, dangerous situations can occur in the case of an overcharged vehicle. In addition, after a route has been traveled, the overload would have to be removed from the vehicle. For electrically driven vehicles, a load-dependent range prediction is also relevant in order to be able to assess how much loading can still be realized in order to arrive without additional charging of the battery.Proceeding from this, the invention is based in particular on the object of being able to increase the accuracy in the determination of the static mass.This object is achieved according to the invention by a method according to claim 1. Preferred developments of the invention are given in the dependent claims and in the following description.A method for detecting loads in a vehicle, which has a chassis having a plurality of vehicle wheels which stand or roll on a ground, and a vehicle body which is supported by the chassis and is resiliently supported on unsprung components of the chassis, which components comprise the vehicle wheels, each of which has associated therewith a wheel stroke characterizing its respective distance from the vehicle body in a vehicle vertical direction, wherein, in a standstill of the vehicle, at least one or more of the wheel strokes are determined as static wheel stroke information, preferably by measurement, and a mass of the vehicle and / or of the vehicle body is determined as static mass from the static wheel stroke information and from a suspension information characterizing the suspension behavior of the vehicle body, in particular with respect to the unsprung components, is further developed according to the invention in particular in thatat least one driving dynamic variable of the vehicle is determined during a travel of the vehicle,a mass of the vehicle and / or of the vehicle body is determined as a dynamic mass on the basis of the at least one driving dynamic variable of the vehicle, andcomparing the dynamic mass with the static mass and forming and / or correcting the suspension information as a function thereof.The partial expression above "depending on this" means in particular "depending on this comparison" and / or "depending on the result of this comparison". The method for detecting loads can also be referred to as a method for detecting masses, for example.By means of the development according to the invention, the suspension information can be formed and / or corrected on the basis of the relatively accurately determinable dynamic mass, which leads to an increase in the accuracy of the suspension information and thus to an increase in the accuracy in the determination of the static mass.The vehicle is assigned in particular a vehicle coordinate system which preferably comprises a vehicle longitudinal axis and / or a vehicle transverse axis and / or a vehicle vertical axis. The vehicle longitudinal axis runs in particular in a vehicle longitudinal direction. The vehicle transverse axis runs in particular in a vehicle transverse direction. The vehicle vertical axis runs in particular in the vehicle vertical direction, which is also referred to as a vertical direction, for example. The vehicle longitudinal axis, the vehicle transverse axis and the vehicle vertical axis form, in particular, an orthogonal right-hand system in this order. The expression "at least one" also encompasses, in particular, the meaning of "one" or "exactly one".The vehicle body supported by the chassis is preferably spring-supported by vehicle springs on the unsprung components of the chassis. Preferably, each vehicle wheel is assigned one or at least one of the vehicle springs. The suspension information comprises in particular information about at least one or more of the vehicle springs or about the or all vehicle springs.Instead of the term "suspension information", the term "at least one suspension information" or the term "suspension information" can also be used, for example. The suspension information comprises in particular at least one or more suspension information values which characterize, for example, at least one or more spring stiffnesses and / or at least one or more spring characteristic curves. The suspension information is preferably stored in a storage unit, in particular in the form of the at least one or more suspension information values. For example, the suspension information is stored, in particular in the form of the at least one or more suspension information values, as at least one table or in the form of at least one table. Intermediate values not stored in the at least one table can be determined, for example, by interpolation. The at least one table is in particular a look-up table.The vehicle wheels are preferably articulated on the vehicle body by means of chassis control arms. In particular, each vehicle wheel is assigned one or at least one of the chassis control arms. For example, each vehicle wheel is assigned two or at least two, three or at least three or four or at least four of the chassis control arms.The vehicle wheels are preferably connected to the vehicle body by dampers. In particular, each vehicle wheel is assigned one or at least one of the dampers.According to an advantageous embodiment, the vehicle has at least one drive motor, by means of which at least one of the vehicle wheels or at least two of the vehicle wheels or the or all vehicle wheels is or are driven and / or can be driven. The at least one drive motor preferably comprises a motor shaft which, for example with the interposition of at least one vehicle transmission, is preferably indirectly or at least indirectly coupled and / or couplable to at least one or to at least two of the vehicle wheels or to the or all vehicle wheels.The mass of the load of the vehicle is preferably determined from the static mass, in particular taking into account the mass of the unloaded vehicle and / or of the unloaded vehicle structure. For example, the mass of the unladen vehicle and / or the unladen vehicle body is subtracted from the static mass. Additionally or alternatively, the mass of the load of the vehicle is determined from the dynamic mass, in particular taking into account the mass of the unloaded vehicle and / or of the unloaded vehicle structure. For example, the mass of the unladen vehicle and / or the unladen vehicle body is subtracted from the dynamic mass. The mass of the unladen vehicle and / or of the unladen vehicle structure is preferably known and / or predefined.Preferably, when the vehicle is at a standstill, the wheel stroke or all of the wheel strokes are determined as, in particular, the static wheel stroke information, preferably by measurement. The static wheel stroke information comprises in particular information about at least one or more of the wheel strokes or about the or all wheel strokes when the vehicle is at a standstill. Instead of the expression "static wheel stroke information", for example, the expression "at least one static wheel stroke information" or the expression "static wheel stroke information" can also be used. The static wheel stroke information comprises in particular at least one or more static wheel stroke values. The static wheel stroke information item is or is preferably stored in the or a storage unit, in particular in the form of the at least one or more static wheel stroke values.During the travel of the vehicle, at least one or more of the wheel strokes or the or all of the wheel strokes are preferably determined as dynamic wheel stroke information, preferably by measurement. The dynamic wheel stroke information comprises in particular information about at least one or more of the wheel strokes or about the or all of the wheel strokes during the travel of the vehicle. Instead of the expression "dynamic wheel stroke information", it is also possible to use, for example, the expression "at least one dynamic wheel stroke information" or the expression "dynamic wheel stroke information". The dynamic wheel stroke information comprises in particular at least one or more dynamic wheel stroke values. The dynamic wheel stroke information item is or is preferably stored in the or a storage unit, in particular in the form of the at least one or more dynamic wheel stroke values.According to the invention, the at least one driving dynamics variable of the vehicle comprises at least one variable of the longitudinal dynamics of the vehicle. In this case, the dynamic mass can be determined, for example, according to DE 10 2013 211 243 A1. Preferably, the dynamic mass and / or a longitudinal mass information characterizing the mass of the vehicle and / or of the vehicle body is determined on the basis of at least one or the at least one variable of the longitudinal dynamics of the vehicle. For example, the dynamic mass is determined and / or formed from the longitudinal mass information.According to the invention, the at least one driving dynamics variable of the vehicle comprises at least one variable of the vertical dynamics of the vehicle. In this case, the dynamic mass can be determined, for example, according to EP 1 863 659 B1. Preferably, the dynamic mass and / or a vertical mass information characterizing the mass of the vehicle and / or of the vehicle body is determined on the basis of, or inter alia, at least one or the at least one variable of the vertical dynamics of the vehicle. For example, the dynamic mass is determined and / or formed from the vertical mass information.According to the invention, the or a longitudinal mass information characterizing the mass of the vehicle and / or of the vehicle structure is determined on the basis of at least one or the at least one variable of the longitudinal dynamics of the vehicle, and the or a vertical mass information characterizing the mass of the vehicle and / or of the vehicle structure is determined on the basis of or, inter alia, on the basis of at least one or the at least one variable of the vertical dynamics of the vehicle. The dynamic mass is preferably determined and / or formed from or on the basis of or taking into account the longitudinal mass information and / or the vertical mass information. In particular, in this case, the dynamic mass is determined on the basis of both the longitudinal dynamics and the vertical dynamics, whereby the accuracy in determining the dynamic mass can be further increased. The longitudinal ground information is determined, for example, according to DE 10 2013 211 243 A1. The vertical mass information is determined, for example, according to EP 1 863 659 B1.The vertical mass information can be additionally determined, for example, on the basis of at least one or the at least one variable of the longitudinal dynamics of the vehicle. Additionally or alternatively, the longitudinal mass information can be determined e.g. additionally on the basis of at least one or the at least one variable of the vertical kinematics of the vehicle. The dynamic mass is determined, for example, on the basis of at least one or the at least one variable of the longitudinal dynamics of the vehicle and / or on the basis of at least one or the at least one variable of the vertical dynamics of the vehicle.The at least one driving dynamic variable comprises in particular one or more driving dynamic variables. For example, the at least one driving dynamic variable comprises a speed of the vehicle and / or at least one acceleration of the vehicle and / or at least one acceleration of the vehicle structure and / or a drive torque output by the at least one drive motor and / or a rotational speed of the motor shaft of the at least one drive motor and / or at least one or more of the or all wheel strokes occurring during the travel and / or the dynamic wheel stroke information and / or at least one wheel acceleration of at least one or each vehicle wheel and / or at least one wheel speed of at least one or each vehicle wheel and / or information about a brake actuation of the vehicle and / or at least one or more rotational speeds or rotational rates of the vehicle structure, in particular about one or more of the axes of the vehicle coordinate system.An acceleration in the vehicle longitudinal direction is referred to in particular as a longitudinal acceleration. An acceleration in the vehicle transverse direction is referred to in particular as transverse acceleration. An acceleration in the vehicle vertical direction is referred to in particular as vertical acceleration.The at least one acceleration of the vehicle is or comprises, for example, a longitudinal acceleration of the vehicle and / or a lateral acceleration of the vehicle and / or a vertical acceleration of the vehicle.The at least one acceleration of the vehicle body is or comprises, for example, a longitudinal acceleration of the vehicle body and / or a lateral acceleration of the vehicle body and / or a vertical acceleration of the vehicle body.The at least one wheel acceleration of the at least one or each vehicle wheel comprises, for example, a longitudinal acceleration of the at least one or each vehicle wheel and / or a lateral acceleration of the at least one or each vehicle wheel and / or a vertical acceleration of the at least one or each vehicle wheel.The at least one or more rotational speeds or rotational rates of the vehicle body (body rotational rates) are or comprise in particular a rotational speed or rotational rate of the vehicle body about the or a vehicle longitudinal axis and / or a rotational speed or rotational rate of the vehicle body about the or a vehicle transverse axis and / or a rotational speed or rotational rate of the vehicle body about the or a vehicle vertical axis.The at least one acceleration of the vehicle can be determined, for example, by at least one acceleration sensor, which is preferably a multidimensional, in particular a three-dimensional acceleration sensor. Preferably, such an acceleration sensor is provided on at least one or on each vehicle wheel.The at least one acceleration of the vehicle body and / or the at least one rotational speed or rotation rate of the vehicle body can be determined, for example, by at least one inertial sensor, which preferably comprises three acceleration sensors and three rotation rate sensors. The inertial sensor is preferably provided on the vehicle body.The at least one wheel speed of the at least one or each vehicle wheel can be determined in particular by at least one wheel speed sensor provided on the at least one vehicle wheel or by at least one wheel speed sensor provided on each vehicle wheel.The speed of the vehicle can be determined, for example, by a tachometer and / or by evaluating the or each wheel speed.The at least one or each wheel stroke and / or the static wheel stroke information and / or the dynamic wheel stroke information can be determined in particular by at least one or more height level sensors.The at least one drive torque output by the drive motor and / or the rotational speed of the motor shaft of the at least one drive motor are provided in particular by a control unit and / or by a bus system of the vehicle. The control device is or comprises, for example, an engine control device. The bus system is or comprises, for example, a CAN bus.The vehicle preferably comprises a vehicle brake system and / or a brake lever. The brake lever is in particular part of the vehicle brake system and / or connected to the latter. The information about a brake actuation of the vehicle is characterized or provided, for example, by at least one brake pressure of the vehicle brake system of the vehicle and / or by an actuation path of the brake lever of the vehicle and / or by an actuation angle of the brake lever of the vehicle and / or by a brake lever force exerted on the brake lever of the vehicle. The brake lever is preferably a pedal and is also referred to as a brake pedal, for example.The information about a brake actuation of the vehicle is provided, for example, by the control unit, in particular via the bus system of the vehicle.According to an advantageous development, the dynamic mass is additionally determined on the basis of at least one supplementary variable.For example, the at least one supplementary variable comprises the or a brake pressure of the vehicle brake system and / or the or an actuation path of the brake lever or the or an actuation angle of the brake lever and / or the or a brake lever force exerted on the brake lever.Preferably, a brake disc is provided on at least one or on each of the vehicle wheels. Preferably, the temperature of the or each brake disc is measured. Advantageously, the at least one supplementary variable comprises the temperature of the at least one or each brake disc.The vehicle preferably comprises a travel lever. The at least one supplementary variable preferably comprises an actuation travel of the travel lever and / or an actuation angle of the travel lever and / or a travel lever force exerted on the travel lever. The drive lever is preferably a pedal and is also referred to as an accelerator pedal or accelerator pedal, for example.On the basis of the comparison and / or as a result of the comparison of the dynamic mass with the static mass, evaluation information is preferably formed which characterizes in particular a deviation of the dynamic mass from the static mass and / or a difference between the dynamic mass and the static mass. For example, the evaluation information comprises or is formed by one or at least one evaluation characteristic.The suspension information and / or the at least one or more suspension information values are preferably formed and / or corrected as a function of the comparison of the dynamic mass with the static mass and / or as a function of or taking into account the evaluation information.The suspension information preferably comprises one or at least one spring stiffness information. The suspension information item and / or the at least one spring stiffness information item preferably characterizes at least one spring stiffness in the suspension behavior of the vehicle body. In particular, the suspension information item and / or the spring stiffness information item comprises at least one or more spring stiffness values, which in particular each form one of the spring stiffness information items. Advantageously, the at least one or more spring stiffness values characterize at least one or more spring characteristic lines. The spring stiffness information is preferably formed and / or corrected as a function of the comparison of the dynamic mass with the static mass and / or as a function of the evaluation information. By means of the spring stiffness information, it is possible, for example, to take into account a non-linear and / or non-proportional spring behavior. The spring stiffness information is or is preferably stored as at least one table or in the form of at least one table, in particular in the or a storage unit. Intermediate values not stored in the at least one table can be determined, for example, by interpolation. The at least one table is in particular a look-up table.The suspension behavior of the vehicle body has, in particular, a hysteresis with respect to a load and a discharge of the vehicle and / or of the vehicle body. The hysteresis is preferably or is taken into account in the suspension information and / or in the at least one spring stiffness information. The suspension information item and / or the at least one spring stiffness information item preferably comprises one or at least one hysteresis information item, which characterizes the hysteresis in particular. The suspension information and / or the hysteresis information preferably comprises at least one or more hysteresis values, which in particular each form one of the suspension information values. For example, a different static mass is assigned to the vehicle and / or the vehicle body with the same wheel stroke or the same wheel strokes and / or with the same static wheel stroke information depending on whether the vehicle is loaded or unloaded. The hysteresis information comprises or characterizes in particular at least one or more load spring stiffness values and / or at least one or more discharge spring stiffness values and / or at least one or more load spring characteristic curves and / or at least one or more discharge spring characteristic curves. The hysteresis information is preferably formed and / or corrected as a function of the comparison of the dynamic mass with the static mass and / or as a function of the evaluation information. By means of the hysteresis information it is possible, for example, to take into account a hysteresis in the suspension behavior. The hysteresis information is or is preferably stored as at least one table or in the form of at least one table, in particular in the or a storage unit. Intermediate values not stored in the at least one table can be determined, for example, by interpolation. The at least one table is in particular a look-up table.According to an advantageous development, when the vehicle is at a standstill, a load change of the vehicle is detected, preferably by a change in the mass of the vehicle and / or of the vehicle structure and / or by a change in the at least one or more wheel strokes and / or by a change in the static wheel stroke information, and load change information characterizing this change is provided. Specifically, the load change information includes information on whether the load state of the vehicle remains unchanged or whether the vehicle is loaded or unloaded. Thus, it is possible, for example, to use the hysteresis information for determining the static mass. The static mass is preferably additionally determined taking into account the load change information. The load change information comprises, for example, at least one load change information value or is formed thereby.According to an advantageous embodiment, the vehicle comprises a parking brake, for example in the form of a hand brake. In particular, the suspension behavior of the vehicle body is dependent on the actuation state of the parking brake. The actuation state of the parking brake is preferably or is taken into account in the suspension information and / or in the at least one spring stiffness information and / or in the at least one hysteresis information, for example by at least one spring stiffness or spring characteristic curve representing a released parking brake and at least one other spring stiffness or spring characteristic curve representing an actuated parking brake. Preferably, when the vehicle is at a standstill, the actuation state of the parking brake is detected and parking brake actuation information characterizing this state is provided. The static mass is advantageously additionally determined taking account of the parking brake actuation information. The parking brake actuation information comprises, for example, at least one parking brake actuation information value or is formed thereby.According to an advantageous development, when the vehicle is at a standstill, in particular on the basis of the static wheel stroke information, a piece of centroid information characterizing a centroid of the vehicle is determined. Preferably, on the basis of the centroid information, a centroid displacement, in particular a charge-induced centroid displacement, is determined.According to an advantageous embodiment, the generation and / or the correction of the suspension information is carried out by means of an evaluation unit, which in particular comprises an artificial intelligence, such as a neural network, for example, and is preferably connected to the bus system. For example, the formation and / or the correction of the suspension information takes place on the basis of and / or by minimizing a quality function. Additional vehicle information is preferably supplied to the evaluation unit and / or the artificial intelligence, which is taken into account in particular when forming and / or correcting the suspension information.Initially, the suspension information is in particular predefined. However, if initially no or no meaningful suspension information is predefined, then an initial or initial suspension information can be formed, for example, on the basis of a dynamic mass determined during the trip.Preferably, a wheel contact force of the at least one or of the respective or each vehicle wheel is determined from the suspension information and from the static or dynamic wheel stroke information, the wheel stroke of which is incorporated, for example, into the static or dynamic wheel stroke information and / or into the formation thereof. For example, the wheel contact force per vehicle corner or corner of the vehicle is or is therefore determinable and / or determined. Preferably, the or a mass of the vehicle and / or of the vehicle body is determined from the wheel contact force or from the wheel contact forces as, in particular, the static mass. For example, the static mass of the vehicle is determined from the wheel contact force or from the wheel contact forces. The or each wheel contact force is also referred to as normal force, for example. For example, the or each wheel contact force is a static wheel contact force, which occurs in particular when the vehicle is at a standstill. Additionally or alternatively, e.g. a dynamic wheel contact force of the at least one or of the respective or each vehicle wheel can be determined, for example during the or a journey of the vehicle.In particular, at least one spring stiffness is required for determining the static mass from the static wheel stroke information, which spring stiffness can also be referred to as wheel stroke stiffness, for example. In addition, it is advantageous to take account of the hysteresis in relation to the charging and the discharging. With the invention, it is possible in particular to learn the suspension information, such as the information about the spring stiffness and / or about the hysteresis, on the basis of the dynamic mass determined during the travel. The dynamic mass ascertained by dynamic vehicle trajectories can be detected with a high quality of estimation. In addition, on the basis of an average value of the relative deflection of wheel to vehicle body over the period of a vehicle movement, the estimation quality of the determination of the dynamic mass can be increased. In particular, in electrically driven vehicles, the quality of estimation can be increased by the linear relationship between motor current and drive force. The spring characteristic curves of the static load detection are adapted on the basis of the comparison of determined static mass to dynamic mass determined later. Online adaptation is possible here on the basis of an optimization process (genetic algorithm) or on the basis of approaches based on artificial intelligence.In addition, data from the bus system or a bus system of the vehicle can be used to take into account further disturbing influences such as open doors, changing damper modes, temperature, standstill times and / or setting times. Further, the influence of a road gradient may be taken into account in determining the dynamic mass and the static mass. Further, it is possible to network vehicles of the same construction type to shorten the time for learning the suspension information.The invention makes it possible to determine the static mass by determining the contact force / normal force per wheel via the wheel stroke rigidity per wheel and the deflection of the wheel relative to the vehicle body on the basis of the formed and / or corrected suspension information, which in particular comprises hysteresis information characterizing at least one hysteresis characteristic curve. The hysteresis characteristic curve takes into account the loading and unloading process and maps the static mass determined on the basis of the relative deflection of vehicle wheel to vehicle body to the real vehicle mass. To improve the imaging quality of the hysteresis characteristic curve and to adapt the wheel stroke stiffness, dynamic movement trajectories of the vehicle are used to dynamically determine the vehicle mass as a dynamic mass, so that the spring characteristics of the suspension information are continuously learned.The invention is described below with reference to a preferred embodiment with reference to the drawings. In the drawing, the following are shown: FIG. 1 shows a schematic plan view of a vehicle, FIG. 2 shows a schematic view of a wheel suspension of the vehicle, FIG. 3 is a schematic view of an apparatus for carrying out the method according to the invention; and FIG. 4 shows a schematic diagram for illustrating the method according to the invention according to one embodiment.FIG. 1 shows a schematic plan view of a vehicle 1 which has a vehicle body 2 and a chassis 3 with a plurality of wheel suspensions 4, 5, 6 and 7, of which the wheel suspensions 4 and 5 are assigned to a front axle 8 and the wheel suspensions 6 and 7 are assigned to a rear axle 9. Each wheel suspension comprises a vehicle wheel, wherein the wheel suspension 4 has the vehicle wheel 10, the wheel suspension 5 has the vehicle wheel 11, the wheel suspension 6 has the vehicle wheel 12 and the wheel suspension 7 has the vehicle wheel 13. Furthermore, a coordinate system is shown with a vehicle longitudinal axis x, a vehicle transverse axis y and a vehicle vertical axis z.FIG. 2 shows a schematic view of the wheel suspension 4 which has a wheel carrier 14 which is connected by a joint 15 preferably designed as a ball joint to a chassis link 16 preferably designed as a suspension arm, the end of which remote from the wheel carrier 14 is articulated on the vehicle body 2 by at least one joint 17 preferably designed as a rubber bearing. Furthermore, the wheel carrier 14 is connected, in particular fixedly, to a suspension strut 18, the end of which remote from the wheel carrier 14 is connected to the vehicle body 2 by a suspension strut support bearing 19. The suspension strut 18 comprises a vehicle spring 20 and a damper 21, which is surrounded in particular by the vehicle spring 20, which is preferably designed as a helical spring. A wheel bearing 22 is fastened to the wheel carrier 14, by means of which the vehicle wheel 10 is mounted on the wheel carrier 14 such that it can rotate about a wheel rotational axis 23. Furthermore, a tie rod 24 is connected to the wheel carrier 14 by means of a joint 25 preferably designed as a ball joint. The vehicle wheel 10 is in contact with a ground surface 26 which is, for example, a road or roadway. In particular, the vehicle wheel 10 exerts a, for example static, wheel contact force Ka on the underlying surface 26. It should be noted that the vehicle coordinate system shown in FIG. 1 is shown in a displaced manner in FIG. 2.At the joint 17 a height sensor 27 is provided, by means of which a wheel stroke h of the vehicle wheel 10 with respect to a reference position 28 can be detected by measuring an angle α enclosed between the vehicle body 2 and the chassis arm 16, and a wheel stroke signal Sh characterizing this wheel stroke h can be provided. The reference position 28 is in particular stationary with respect to the vehicle body 2, and a corresponding height sensor is preferably provided on the other wheel suspensions 5, 6 and 7, by means of which sensor a wheel stroke of the respective vehicle wheel can be detected and a wheel stroke signal characterizing this wheel stroke can be provided. In this case, the height sensors together form, in particular, a height sensor arrangement. The wheel stroke signal Sh and / or the wheel stroke signals form in particular wheel stroke information.A body sensor arrangement 29 is provided on the vehicle body 2, which has three translatory acceleration sensors 30, 31 and 32 and three rotation rate sensors 33, 34 and 35 (see FIG. 3 ). In this case, the acceleration sensor 30 provides, in particular, an acceleration signal Sx characterizing a longitudinal acceleration of the vehicle body 2. Furthermore, the acceleration sensor 31 provides, in particular, an acceleration signal Sy characterizing a transverse acceleration of the vehicle body 2. Finally, the acceleration sensor 32 provides, in particular, an acceleration signal Sz characterizing a vertical acceleration of the vehicle body 2. The rotation rate sensor 33 provides, in particular, a rotation rate signal Syz characterizing a rotation speed or rotation rate of the vehicle body 2 about the vehicle longitudinal axis x. Furthermore, the rotation rate sensor 34 provides, in particular, a rotation rate signal Szx characterizing a rotational speed or rotation rate of the vehicle body 2 about the vehicle transverse axis y. Finally, the rotation rate sensor 35 provides, in particular, a rotation rate signal Sxy characterizing a rotation speed or rotation rate of the vehicle body 2 about the vehicle vertical axis z.Furthermore, a chassis sensor arrangement 36 is provided on the wheel carrier 14, which has three translatory acceleration sensors 37, 38 and 39 (see FIG. 3 ). Optionally, the chassis sensor arrangement 36 can additionally have three rotation rate sensors. In this case, the acceleration sensor 37 provides, in particular, an acceleration signal Fx characterizing a longitudinal acceleration of the vehicle wheel 10. Furthermore, the acceleration sensor 38 provides, in particular, an acceleration signal Fy characterizing a lateral acceleration of the vehicle wheel 10. Finally, the acceleration sensor 39 provides, in particular, an acceleration signal Fz characterizing a vertical acceleration of the vehicle wheel 10.In addition, a wheel speed sensor 40 is provided on the wheel carrier 14 or on the wheel bearing 22, by means of which a rotational speed of the vehicle wheel 10 can be detected and a wheel speed signal Snr characterizing this rotational speed can be provided. Preferably, a corresponding wheel speed sensor is provided on the other wheel suspensions 5, 6 and 7, by means of which a wheel speed of the respective vehicle wheel can be detected and a wheel speed signal characterizing this wheel speed can be provided.A brake disc 61 is provided on the vehicle wheel 10. Preferably, a brake disk temperature sensor 62 is provided on or in the region of the brake disk 61, by means of which a brake disk temperature signal Sbs characterizing the temperature of the brake disk 61 can be provided. For example, a corresponding brake disk temperature sensor is provided on the other wheel suspensions 5, 6 and 7, by means of which a brake disk temperature signal characterizing the temperature of the respective brake disk can be provided.The wheel suspension 5 is preferably constructed laterally reversed with respect to the wheel suspension 4. Furthermore, the wheel suspension 7 is preferably constructed laterally reversed with respect to the wheel suspension 6. In particular, the front axle 8 is of steerable design. The rear axle is, for example, of steerable or non-steerable design. Apart from this, the wheel suspensions 4, 5, 6 and 7 are constructed in particular in the same way.As can be seen from FIG. 3, the sensors of the sensor arrangements 29 and 36 and the height sensor 27 and the wheel speed sensor 40 are connected to an evaluation device 41. Chassis sensor arrangements formed identically to the chassis sensor arrangement 36 are preferably provided in the wheel suspensions 5, 6 and 7 and are connected to the evaluation device 41. Preferably, if present, the height level sensors and / or wheel speed sensors provided in the wheel suspensions 5, 6 and 7 are also connected to the evaluation device 41.The vehicle 1 comprises a drive motor 42 having a motor shaft 43 coupled to the vehicle wheels 10 and 11, for example via at least one vehicle transmission. Additionally or alternatively, the motor shaft 43 is coupled, for example, via at least one or the at least one vehicle transmission, e.g., to the vehicle wheels 12 and 13. The drive motor 42 is connected to a control unit 44, which in turn is connected to a bus system 45. The control unit 44 is or comprises preferably an engine control unit or is connected, for example, to an engine control unit. Bus system 45 includes, for example, a CAN bus.Furthermore, the vehicle 1 comprises a brake pedal 46, on which a brake pedal sensor 47 connected to the control unit 44 is provided, by means of which an actuation of the brake pedal 46 can be detected and a brake signal Sb characterizing this actuation can be provided. The brake pedal 46 is connected in particular to a vehicle brake system of the vehicle 1 and / or forms part thereof. Alternatively, a brake pressure of the or a vehicle brake system can also be detected and a signal characterizing this brake pressure can be provided as brake signal Sb. The brake signal Sb thus characterizes information about a brake actuation.In addition, the vehicle 1 comprises an actuating device 48 for a parking brake of the vehicle 1, such as a hand brake. By means of the actuating device 48 connected to the control device 44, in particular a parking brake actuating signal Sfb characterizing the actuating state of the parking brake can be provided. The actuating device 48 comprises, for example, a lever connected to the parking brake, such as, for example, a hand lever, a pedal connected to the parking brake or an actuator connected to the parking brake and having an electric actuating switch.The vehicle 1 comprises, for example, a tachometer 49, which is preferably connected to the control unit 44 and by means of which a speed signal Sv characterizing the speed of the vehicle 1 can be provided. The tachometer 49 may include and / or be connected to the wheel speed sensor or sensors 40. Alternatively, the tachometer may also be provided in addition to the wheel speed sensor or sensors 40. In particular, the tachometer determines the speed of the vehicle 1 from the wheel rotational speeds detected by means of the wheel rotational speed sensor or sensors 40.The evaluation device 41 is connected to the bus system 45 by means of which the evaluation device 41 is supplied with the brake actuation signal Sb characterizing the information about a brake actuation, the parking brake actuation signal Sfb characterizing the actuation state of the parking brake, a drive torque signal Sma characterizing the drive torque output by the drive motor 42 and a motor shaft rotational speed signal Snw characterizing a rotational speed of the motor shaft 43. Preferably, the evaluation device 41 is also supplied by the bus system 45 with the speed signal Sv characterizing the current speed of the vehicle 1, which the evaluation device 41 could also determine from the wheel speed signal Snr or the wheel speed signals, for example.Optionally, the brake disk temperature sensor 62 is connected to the evaluation device 41. For example, if present, the brake disk temperature sensors provided in the wheel suspensions 5, 6 and 7 are also connected to the evaluation device 41.FIG. 4 shows a schematic diagram for illustrating the method according to the invention for load detection according to one embodiment. In a step 50, at least one or more of the wheel strokes are detected as wheel stroke information 51 when the vehicle 1 is at a standstill, wherein the wheel stroke information 51 obtained when at a standstill is referred to as static wheel stroke information. From the static wheel stroke information 51 and from a suspension information 52 characterizing the suspension behavior of the vehicle body 2, a mass of the vehicle 1 and / or of the vehicle body 2 is determined as a static mass m_stat. For this purpose, the suspension information 52 comprises at least one or more suspension information values 53 which characterize at least one spring characteristic curve. Initially, the suspension information 52 is in particular predefined.The suspension behavior of the vehicle body 2 has hysteresis with respect to load and discharge of the vehicle, the hysteresis being taken into account in the suspension information. The suspension information values 53 thus preferably represent one or at least one complete spring characteristic curve, including hysteresis information. When the vehicle 1 is at a standstill, it is detected, for example by changing the at least one or more wheel strokes, whether the vehicle 1 is loaded or unloaded. Thus, hysteresis may be taken into account in determining the static mass.Furthermore, the parking brake influences the suspension behavior of the vehicle 1 in the stationary state. For example, the at least one spring characteristic curve when the parking brake is actuated differs from the at least one spring characteristic curve when the parking brake is released. The suspension information preferably comprises at least one or more suspension information values 54, which characterize at least one additional spring characteristic curve, wherein the suspension information values 54 represent in particular an actuated parking brake. The suspension information values 53 thus preferably represent a released and / or unactuated parking brake. The suspension information values 54 preferably represent one or at least one complete spring characteristic curve, including hysteresis information.In a step 55, vehicle dynamic quantities are determined during a journey of the vehicle 1. The vehicle dynamics variables determined include, in particular, the speed of the vehicle 1 and / or the acceleration of the vehicle 1 in the vehicle longitudinal direction x and / or the drive torque output by the drive motor 42 and / or the rotational speed of the motor shaft 43 of the at least one drive motor. The determined driving dynamics variables preferably also include the acceleration of vehicle 1 in vehicle transverse direction y and / or the wheel speed(s) of at least one or more of the vehicle wheels.Based on these driving dynamics variables, longitudinal mass information m_I characterizing the mass of the vehicle and / or of the vehicle body is now determined in a step 56. Preferably, the brake signal Sb characterizing the information about a brake actuation is also taken into account. In addition, other variables can be taken into account for the determination of the longitudinal mass information m_l.The determination of the longitudinal mass information m_l corresponds in particular to a determination of the mass of the vehicle and / or of the vehicle body on the basis of the longitudinal dynamics of the vehicle 1, which is explained, for example, in DE 10 2013 211 243 A1.The vehicle dynamics variables determined additionally include, in particular, the acceleration of the vehicle body in the vehicle vertical direction z and / or the wheel accelerations of the vehicle wheels in the vehicle vertical direction z and / or the wheel strokes occurring at at least one or at a plurality of the vehicle wheels or at all vehicle wheels. The determined driving dynamics variables preferably also include the acceleration of the vehicle body in the vehicle transverse direction y and / or the acceleration of the vehicle body in the vehicle longitudinal direction x and / or the wheel accelerations of the vehicle wheels in the vehicle transverse direction y and / or the wheel accelerations of the vehicle wheels in the vehicle longitudinal direction x and / or the rotational speed or rotation rate of the vehicle body 2 about the vehicle longitudinal axis x and / or the rotational speed or rotation rate of the vehicle body 2 about the vehicle transverse axis y and / or the rotational speed or rotation rate of the vehicle body 2 about the vehicle vertical axis z.On the basis of these driving dynamics variables, vertical mass information m_v characterizing the mass of the vehicle and / or of the vehicle body is now determined in a step 57. In addition, other variables can be taken into account for the determination of the vertical mass information m_v. The wheel stroke information obtained during travel from the wheel stroke or strokes is referred to in particular as dynamic wheel stroke information.The determination of the vertical mass information m_v corresponds in particular to a determination of the mass of the vehicle and / or of the vehicle body on the basis of or, inter alia, on the basis of the vertical dynamics of the vehicle 1, which is explained, for example, in EP 1 863 659 B1.In a step 58, a mass of the vehicle and / or of the vehicle body is determined as dynamic mass m_dyn on the basis of longitudinal mass information m_l and vertical mass information m_v. In this case, the vertical mass information m_v can be determined several times beforehand and then averaged. The same applies to the longitudinal mass information m_l.The determination of the dynamic mass m_dyn can be determined, for example, by averaging the longitudinal mass information m_l and the vertical mass information m_v. For example, the dynamic mass m_dyn is determined as an unweighted or as a weighted arithmetic mean from the longitudinal mass information m_l and the vertical mass information m_v. In the case of a weighted arithmetic mean, it is possible, for example, to take account of different precisions and / or errors in the determination of the longitudinal mass information m_l and the vertical mass information m_v. Since the longitudinal mass information m_l and the vertical mass information m_v are determined in different ways, a plausibility check is also possible, for example in such a way that the determined mass information is plausible at least when it does not deviate from one another beyond a predefined amount. Thus, implausible mass information may be discarded. It is also possible for the dynamic mass m_dyn to be determined only from or on the basis of the longitudinal mass information m_l. In this case, the vertical mass information m_v serves, for example, merely for plausibility checking. Conversely, it is possible that the dynamic mass m_dyn is determined only from or on the basis of the vertical mass information m_v. In this case, the longitudinal mass information m_l serves, for example, merely for plausibility checking.In a step 59, the dynamic mass m_dyn is compared with the static mass m_stat and evaluation information Sbk characterizing the result of this comparison, in particular in the form of at least one evaluation characteristic number, is provided and fed to an evaluation unit 60 which corrects the suspension information 52 while taking into account the evaluation information Sbk. For this purpose, the evaluation unit 60 can determine, for example, a new suspension information item and thus overwrite the previous suspension information item. In a simple case, the evaluation information Sbk is based only on a difference between the static mass and the dynamic mass. The correction of the suspension information 52 is preferably additionally carried out on the basis of supplementary variables which are made available to the evaluation unit 60, for example by the bus system 45. The evaluation unit 60 comprises in particular an artificial intelligence, such as a neural network.If initially no or no meaningful suspension information 52 is predefined, then an initial or initial suspension information 52 can be formed, for example, on the basis of a dynamic mass determined during the trip, which is indicated by dashed lines.Reference numerals denote reference numerals1 Vehicle 2 Vehicle body 3 Chassis 4 Wheel suspension 5 6 Wheel suspension 7 Wheel suspension 8 Front axle 9 Rear axle 10 Vehicle wheel 11 Vehicle wheel 12 Vehicle wheel 13 Vehicle wheel 14 Wheel carrier 15 Joint 16 Chassis link 17 Joint 18 Suspension strut 19 Suspension strut support bearing 20 Vehicle spring 21 Damper 22 Wheel bearing 23 Wheel rotation axis 24 Tie rod 25 Joint 26 Base 27 Height sensor 28 Reference position 29 Structure sensor arrangement 30 Acceleration sensor 31 Acceleration sensor 32 Acceleration sensor 33 Rotation rate sensor 34 Rotation rate sensor 35 Rotation rate sensor 36 Chassis sensor arrangement 37 Acceleration sensor 38 Acceleration sensor 39 Acceleration sensor 40 Wheel speed sensor 41 Evaluation device 42 Drive motor 43 Motor shaft of the drive motor 44 Control device 45 Bus system 46 Brake pedal 47 Brake pedal sensor 48 Actuating device for parking brake 49 Speedometer 50 Determination of a static mass 51 Static wheel stroke information 52 Suspension information 53 Suspension information value(s) 54 Suspension information value(s) 55 Ascertainment of driving dynamic variables during travel 56 Mass ascertainment on the basis of longitudinal dynamics 57 Mass ascertainment on the basis of vertical dynamics 58 Ascertainment of dynamic mass 59 Comparison of dynamic and static mass 60 Evaluation unit / neural network 61 Brake disk 62 Brake disk temperature sensor α Angle Fx Acceleration signal Fy Acceleration signal Fz Acceleration signal h Wheel stroke Ka Wheel contact force m_dy Dynamic mass m_l Longitudinal mass information m_stat Static mass m_v Vertical mass information Sb Brake actuation signal Sbk Evaluation information Sfb Parking brake actuation signal Sbs Brake disk temperature signal Sh Wheel stroke signal Sma Drive torque signal Snr Wheel speed signal Snw Motor shaft speed signal sx acceleration signal Sy acceleration signal Sz acceleration signal Syz rotation rate signal Szx rotation rate signal Sxy rotation rate signal x vehicle longitudinal axis y vehicle transverse axis z vehicle vertical axis

Claims

Method for detecting loads in a vehicle (1), which has a chassis (3) with a plurality of vehicle wheels (10, 11, 12, 13) which stand or roll on a subgrade (26), and a vehicle body (2) which is supported by the chassis (3) and is supported resiliently on unsprung components of the chassis (3) which comprise the vehicle wheels (10, 11, 12, 13), each of which is assigned a wheel stroke (h) which characterizes its respective distance from the vehicle body (2) in a vehicle vertical direction (z), wherein - at least one or more of the wheel strokes are determined as static wheel stroke information (51) in a standstill of the vehicle (1) and - a mass of the vehicle and / or of the vehicle body is determined as static mass (m_stat) from the static wheel stroke information (51) and from suspension information (52) characterizing the suspension behavior of the vehicle body (2), wherein - during a journey of the vehicle (1) at least one dynamic parameter of the vehicle (1) is determined, - a mass of the vehicle (1) and / or of the vehicle body is determined as dynamic mass (m_dy) on the basis of the at least one dynamic parameter of the vehicle (1), and - the dynamic mass (m_dy) is compared with the static mass (m_stat) and the suspension information (52) is formed or corrected as a function thereof, wherein - the at least one driving dynamics variable of the vehicle (1) comprises at least one variable of the longitudinal dynamics (Sx, Sv, Sb, Sma, Snw) of the vehicle (1) and at least one variable of the vertical dynamics (Sz, Sh, Syz, Szx) of the vehicle (1), characterized in that - on the basis of the at least one variable of the longitudinal dynamics (Sx, Sv, Sb, Sma, Snw) of the vehicle (1) a longitudinal mass information item (m_l) characterizing the mass of the vehicle and / or of the vehicle body is determined, on the basis of or, inter alia, on the basis of the at least one variable of the vertical dynamics (Sz, Sh, Syz, Szx) of the vehicle ( 1) a vertical mass information (m_v) characterizing the mass of the vehicle and / or of the vehicle body is determined, and the dynamic mass (m_dynis determined on the basis of the longitudinal mass information (m_l) and the vertical mass information (m_v).Method according to one of the preceding claims, characterized in that the vehicle (1) has at least one drive motor (42), by means of which at least one of the vehicle wheels (10, 11) is driven or can be driven, wherein the at least one drive motor (42) comprises a motor shaft (43) which is coupled to at least one of the vehicle wheels (10, 11).Method according to Claim 2, characterized in that the at least one driving-dynamic variable comprises a speed (Sv) of the vehicle (1) and / or a longitudinal acceleration (Fx) of the vehicle (1) and / or information about a brake actuation (Sb) of the vehicle (1) and / or a drive torque (Sma) emitted by the drive motor (42) and / or a rotational speed of the motor shaft (Snw).Method according to one of the preceding claims, characterized in that the at least one dynamic parameter of travel comprises a vertical acceleration (Sy) of the vehicle structure (2) and / or at least one or more of the wheel strokes (Sh) occurring during travel and / or at least one wheel acceleration (Fy) of at least one of the vehicle wheels (10) and / or at least one body rotation rate (Syz, Szx) about a vehicle longitudinal axis (x) and / or about a vehicle transverse axis (y).Method according to one of the preceding claims, characterized in that, as a result of the comparison of the dynamic mass (m_dyn) with the static mass (m_stat), evaluation information (Sbk) is formed which characterizes a deviation of the dynamic mass (m_dyn) from the static mass (m_stst), wherein the suspension information (52) is formed and / or corrected as a function of the evaluation information (Sbk).Method according to one of the preceding claims, characterized in that the suspension information (52) comprises a plurality of suspension information values (53, 54) which characterize at least one spring characteristic curve.Method according to one of the preceding claims, characterized in that the suspension behavior of the vehicle structure (2) in relation to a load and a load of the vehicle structure (2) has a hysteresis which is taken into account in the suspension information (52), wherein a load change of the vehicle (1) is detected when the vehicle is at a standstill and load change information characterizing this change is provided, and wherein the static mass (m_stat) is additionally determined taking into account the load change information.Method according to one of the preceding claims, characterized in that the vehicle (1) comprises a parking brake and the suspension behavior of the vehicle body (2) is dependent on the actuation state of the parking brake, which is taken into account in the suspension information (52), wherein, when the vehicle (1) is at a standstill, the actuation state of the parking brake is detected and parking brake actuation information characterizing this state is provided, and wherein the static mass (m_stat) is additionally determined taking into account the parking brake actuation information.Method according to one of the preceding claims, characterized in that the formation and correction of the suspension information (52) takes place with the aid of an evaluation unit (60) which comprises a neural network.Method according to one of the preceding claims, characterized in that the mass of the load of the vehicle (1) is determined from the static mass (m_stat) taking into account the mass of the unloaded vehicle (1) and / or of the unloaded vehicle structure (2).Method according to one of the preceding claims, characterized in that a wheel contact force (Ka) of each vehicle wheel (10, 11, 12, 13) is determined from the suspension information (52) and from the static wheel stroke information (51), the wheel stroke (h) of said wheel contact force entering into the static wheel stroke information (51).

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