Method for controlling a system based on a target wheel parameter, computer program product and vehicle

Abstract

The invention relates to a method (100) for controlling a system (10) for braking at least one wheel (2) of a vehicle (1) to a standstill, wherein the system (10) comprises an electric motor (11) for braking the wheel (2), wherein the method (100) comprises: detecting (101) a braking signal (200) for initiating a functional braking process (201) for braking the vehicle (1) by the system (10) using a control unit (20) of the vehicle (1), defining (103) a finalization section (202) of the functional braking process (201) for reaching a standstill as a function of the braking signal (200) using a target variable module (22) of the control unit (20). The invention further relates to a computer program product and a vehicle (1).

Description

[0001] The invention relates to a method for controlling a system for braking at least one wheel of a vehicle to a standstill with a disturbance variable determination as a function of a target wheel parameter, a computer program product and a vehicle.

[0002] It is well known that in electric vehicles the electric motor and its recuperation in conjunction with the wheel brakes are used to brake a vehicle to a standstill. In this case, a switch is often made from electrical deceleration to mechanical deceleration before the vehicle is reached in order to ensure that it stops. This process is generally referred to as standstill blending. However, standstill blending can be unpleasant for the driver if the vehicle deceleration fluctuates noticeably during the actuator change and / or the steady-state torque after the actuator change has been completed does not roughly correspond to the deceleration torque that existed before the actuator change. Furthermore, the application of the brake can be noticeable acoustically in the form of a squeal. This can lead to a loss of comfort for the driver.

[0003] Furthermore, manufacturing-related influences on a drive axle can affect the control system, for example, if the actual wheel speed deviates from the wheel speed induced by the control of the drive torque of the electric motor. DE 196 32 939 A1 also discloses taking driving dynamics into account when controlling a drive torque. However, it is desirable to enable a more comfortable braking process even under dynamic conditions.

[0004] In conventional braking systems that are not capable of blending, i.e., particularly in those where the brake pedal input directly controls the friction braking torque, the driver can influence stopping comfort by modulating the brake pedal shortly before a standstill. However, if the braking process is performed exclusively regeneratively by the electric motor, inaccurate sensor technology can affect the approach to zero speed and lead to unwanted control effects.

[0005] It is an object of the present invention to at least partially remedy the above-mentioned disadvantages known from the prior art. In particular, it is an object of the present invention to improve the accuracy of controlling a system for braking at least one wheel of a vehicle in order to increase comfort when braking a vehicle to a standstill and / or to increase the recuperative component during braking.

[0006] The above object is achieved by a method having the features of claim 1, a computer program product having the features of claim 11, and a vehicle having the features of claim 12. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the computer program product according to the invention and / or the vehicle according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0007] According to a first aspect of the invention, a method is provided for controlling a system for braking at least one wheel of a vehicle to a standstill. The system comprises an electric motor for braking the wheel. The method comprises, in particular in the form of method steps: - detecting a braking signal to initiate a functional braking process to decelerate the vehicle by the system, in particular by a control unit of the vehicle, - Defining a finalization section of the functional braking process to reach standstill depending on the braking signal, in particular by a setpoint module of the control unit, - Determining at least one pilot control parameter set for specifying a braking trajectory for the vehicle to reach a standstill, ie in particular to complete the finalization section, preferably by the target variable module, wherein the pilot control parameter set comprises a target wheel parameter, - Carrying out a disturbance determination as a function of the target wheel parameter and a wheel condition parameter of the wheel, in particular by means of a correction module of the control unit, - Output of a recuperative control parameter for controlling the electric motor to brake the wheel in the finalization section depending on the disturbance variable determination and the pre-control parameter set, in particular by the control module.

[0008] The vehicle can preferably be a motor vehicle, e.g., in the form of an electric vehicle. The electric motor is preferably a drive motor for driving the wheel of the vehicle. The system can additionally have at least one wheel brake for mechanically braking and / or holding the vehicle at a standstill, which, in particular in the form of a friction brake, acts on at least one wheel of the vehicle. Thus, the system can also be referred to as a braking system. The wheel brake can also be integrated into a brake-by-wire system.

[0009] The braking signal can, in particular, be an actuation signal dependent on the actuation of a driver pedal. However, it is also conceivable that the braking signal is triggered and detected by a vehicle function, for example in the form of a driver assistance system. The functional braking process can, in particular, be understood to mean a braking process controlled by the method, in which the recuperative control parameter is taken into account when controlling the electric motor. It is conceivable, for example, that an emergency braking process is additionally defined for the vehicle in which the functional braking process is deactivated, ie in particular is not used.

[0010] To define the finalization section, the functional braking process can be divided into several sections, for example, and / or a vehicle speed value can be specified at which the finalization section begins. When defining the finalization section as a function of the braking signal, the last section of the functional braking process can be specified, which should or does lead to the vehicle coming to a standstill. It is conceivable that the finalization section is defined under the condition that the standstill is achieved exclusively through the recuperative control parameter. Furthermore, it can be provided that deceleration of the vehicle during the functional braking process before the finalization section occurs exclusively through recuperation. The conclusion of the finalization section can be achieved, in particular, by the vehicle coming to a standstill.

[0011] The pilot control parameter set can, in particular, comprise at least one target specification, in particular in the form of a target variable, by which the braking trajectory is or is to be achieved. The braking trajectory can, for example, comprise a braking profile, in particular in the form of a speed profile, of the vehicle. The braking trajectory can thus, in particular, be fitted into the finalization section. At the same time, the disturbance variable determination based on the target wheel parameter and the wheel condition parameter enables a more accurate representation of the actual conditions in the vehicle and / or a controlled system. This makes it possible to achieve greater control dynamics when controlling the system, in particular the electric motor.

[0012] The target wheel parameter can in particular be a target specification, in particular in the form of a target variable, for the wheel. The target wheel parameter can preferably comprise a target speed of the wheel. For example, the target wheel parameter can be determined as the target speed of the wheel as the ratio of a speed parameter, in particular in the form of a target vehicle speed, and a radius, in particular a dynamic one, of the wheel. The wheel condition parameter can comprise an actual wheel parameter, e.g. in the form of an actual speed of the wheel. The wheel condition parameter can be estimated by calculation and / or measured on the wheel.

[0013] When determining the disturbance variable, a comparison can be made between the wheel state parameter and the target wheel parameter, for example in order to determine a correction variable for determining the recuperative control parameter. In particular, the disturbance variable determination can include the influence of drive train components and / or wheel slip. In particular, a multi-variable controller can be implemented for determining the disturbance variable, which, among other things, regulates the electric motor speed and the wheel speed. Furthermore, the disturbance variable determination can include a disturbance variable observer, in particular of the correction module, and / or an activation logic for self-activation. It can be provided that several wheel brakes are provided. In this case, the disturbance variable determination can preferably be carried out and / or adapted individually and / or separately for each of the wheel brakes.

[0014] When the electric motor is controlled based on the recuperative control parameter, recuperative braking can be performed to decelerate the vehicle using the electric motor. The recuperative control parameter can include, in particular, a torque, particularly in the form of a braking torque, and / or an engine speed for controlling the electric motor. A drive ratio can be taken into account when determining the recuperative control parameter. It can be provided that the recuperative control parameter controls exclusively the electric motor. For example, when the vehicle is stationary, a mechanical control parameter can be output to control the wheel brake. It is conceivable that the pilot parameter set for determining the recuperative control parameter is transferred to the control module without the target wheel parameter.

[0015] The braking trajectory in the finalization section allows the functional braking process to be designed to be comfortable. This can, for example, achieve a comfortable run-down of the vehicle's speed. In particular, it has been recognized within the scope of the present invention that the finalization section can be used to specify a clever braking trajectory in order to reduce or avoid blending of the recuperative braking function of the electric motor with a mechanical wheel brake. This can increase comfort when braking to a standstill and / or simultaneously enable the greatest possible recuperation. In particular, it can be provided that the mechanical wheel brake is only activated after the finalization section of the functional braking process at a standstill has been completed.By determining the disturbance variables, the actual behavior of the wheel can be taken into account when controlling the electric motor, in order to precisely control and / or adjust the vehicle's braking behavior. This allows the braking trajectory to be precisely controlled for standstill, even if the wheel behavior deviates. By determining the disturbance variables, it can be ensured that the vehicle stops at 0 m / s and, in particular, does not roll into the negative speed range from zero speed. This means that, for example, it is not necessary to take into account the situation in the control design when the electric motor temporarily has no influence on the wheel speed.

[0016] Furthermore, in a method according to the invention it is conceivable that the method comprises: - Determining a first control parameter for controlling the electric motor as a function of the pilot control parameter set, in particular by the control module, preferably wherein the recuperative control parameter for outputting the recuperative control parameter is calculated as a function of the disturbance variable determination and the first control parameter. The first control parameter can represent an intermediate result. In particular, the first control parameter can represent a torque, in particular in the form of a braking torque, which is calculated to execute the braking trajectory. It is conceivable that the first control parameter is calculated independently of the wheel state parameter. To determine the recuperative control parameter, it can be provided that the first control parameter is adjusted for a disturbance variable, in particular by a summation function, as a function of the disturbance variable determination.Thus, the first control parameter can be modified in a simple manner, in particular by means of a disturbance variable feedforward, if there is a deviation from the actual wheel condition.

[0017] Preferably, a method according to the invention can be provided that the method comprises: - Determining a set of state parameters of the vehicle, which includes a speed parameter of the vehicle, preferably by an observer module of the control unit, wherein the pre-control parameter set is determined as a function of the speed parameter and the determination of the first control parameter is carried out as a function of the set of state parameters. The set of state parameters can comprise a plurality of state parameters, one of which is the speed parameter. The speed parameter preferably comprises an actual speed of the vehicle, in particular a calculated and / or estimated one. Furthermore, the set of state parameters can comprise further state parameters in the form of driving parameters of the vehicle and / or a vehicle mass.For example, the state parameter set can have a state parameter in the form of a pitch angle of the vehicle, which is determined by comparing a roll and pitch rate and / or height levels on the wheel suspensions. The speed parameter can thus be used to define and / or detect the start of the finalization section and thus the start of the braking trajectory in the finalization section. Assuming that the target speed of the vehicle at the start of the finalization section corresponds to the speed parameter, and preferably the target acceleration corresponds to the current acceleration of the vehicle, the braking trajectory can be determined as a function of speed and / or time. It can be provided that the state parameter set is calculated depending on a vehicle model. The vehicle model can, for example, comprise a single-track or two-track model and / or a point mass model.Furthermore, the vehicle model can be implemented as a semi-vehicle model or a full-vehicle model. The pilot parameter set based on the speed parameter can thus determine an advantageous braking trajectory for the finalization phase of the braking process. This allows for a comfortable deceleration of the vehicle's speed. Thus, center-of-gravity speed control can be implemented when determining the recuperative control parameter depending on the pilot parameter set.

[0018] Preferably, a method according to the invention can provide for the state parameter set, the wheel state parameter, and / or the target wheel parameter to be determined, in particular calculated and / or measured, as a function of sensor signals from a vehicle sensor system of the vehicle. The sensor signals can include, for example, a dynamic parameter of the vehicle, the wheel state parameter, and / or geographical position data of the vehicle. The geographical position data can include, for example, GPS data. The dynamic parameter can include, in particular, a yaw rate, a roll rate, a pitch rate, and / or an inertial variable of the vehicle. A state estimate for the state parameter set can be made based on the sensor signals. In particular, state variables of the controlled system that cannot be measured or cannot be measured with sufficient accuracy can be estimated.For example, the speed parameter, as the absolute speed of the vehicle relative to the ground, can be calculated with high accuracy based on the sensor signals. Preferably, the recuperative control parameter can be determined depending on the state parameter set and / or the sensor signals.

[0019] Furthermore, in a method according to the invention, it can advantageously be provided that the wheel condition parameter for carrying out the disturbance determination is determined using a disturbance observer and / or using sensor signals from a vehicle sensor system on the wheel. In particular, the disturbance observer can comprise a drive model of the system in order to calculate the wheel condition parameter, in particular using the sensor signals. The drive model can be modeled, for example, as a two-mass oscillator. In this case, rotational inertias of the electric motor and / or the wheel can be coupled via a torsion spring model, for example for modeling drive side shafts of the vehicle. Furthermore, the disturbance observer can comprise a Kalman filter and / or a Luenberger observer. The disturbance observer can determine the wheel condition parameter with a higher resolution than is available, for example, from sensor signals.This allows a high degree of accuracy in determining disturbance variables, especially at low vehicle speeds.

[0020] Furthermore, in a method according to the invention, it can advantageously be provided that a permissible range is specified for the target wheel parameter and / or the wheel condition parameter, wherein the disturbance variable determination is taken into account when outputting the recuperative control parameter if the target wheel parameter and / or the wheel condition parameter is outside the permissible range. In particular, the correction variable can be disregarded when outputting the recuperative control parameter if the target wheel parameter is within the permissible range. Thus, for example, a speed limitation can be implemented in which the disturbance variable determination is only activated when a minimum wheel speed is undershot and / or a maximum wheel speed is exceeded.A gradient, which can be configured in particular, can be defined for the permissible range, by means of which the permissible range is reduced over the finalization section and / or over time. For example, at low speeds before the end of the finalization section, it can be assumed that the wheel behaves essentially undynamically with little slip. It can therefore be provided that the influence of the disturbance variable determination is deactivated if the wheel state parameter deviates from the target wheel parameter by more than a predetermined amount. The permissible range can be formed for this purpose by a band that is placed around the target wheel parameter and defines parameter limits. The disturbance variable determination is then only used to support the determination of the first control parameter, i.e. in particular the control based on the pilot control parameter set.

[0021] It is further conceivable in a method according to the invention that the finalization section is defined based on a predefined boundary condition, wherein the boundary condition comprises a minimum speed at the start of the finalization section and / or a specification of an acceleration change and / or a maximum speed of the vehicle. Preferably, the target change in vehicle acceleration is defined by the boundary condition or conditions. The minimum speed can be used to specify the speed from which the vehicle should follow the braking trajectory. By specifying the acceleration change, a maximum acceleration change can be specified, in particular from which the deceleration of the vehicle is not perceived as excessively strong and disruptive.By specifying the maximum speed, it is possible to determine the vehicle speed at which the vehicle must follow the braking trajectory, particularly regardless of the change in acceleration. The boundary conditions can be determined, for example, through test drives.

[0022] Furthermore, in a method according to the invention, it can advantageously be provided that the finalization section is defined by dividing the functional braking process into a pre-braking section and the finalization section, wherein the recuperative control parameter is output in the pre-braking section taking into account the braking signal and in the finalization section decoupled, i.e. in particular independently, from the braking signal. This can allow brief under-braking to improve comfort. It can be provided that the control unit comprises a switching module by which the braking signal is deactivated in the finalization section for determining the recuperative control parameter. This allows the vehicle to follow the braking trajectory without the braking signal acting as a disturbance variable.

[0023] It is further conceivable in a method according to the invention that, after the conclusion of the finalization section, a holding process is carried out in which the recuperative control parameter is reduced and a mechanical control parameter for a mechanical wheel brake of the wheel is increased. The mechanical wheel brake can comprise, for example, a disc brake and / or drum brake. The mechanical wheel brake can comprise an electric or hydraulic actuator in order to apply an actuating force depending on the mechanical control parameter. The mechanical control parameter can comprise a torque, in particular in the form of a braking torque, and / or a braking pressure of the wheel brake. In particular, it can be provided that the mechanical wheel brake is only activated after the conclusion of the finalization section of the functional braking process at a standstill. The mechanical wheel brake can act as a parking brake.This allows the vehicle to be secured against rolling away, while the functional braking process is carried out comfortably using the recuperative control parameter.

[0024] Within the scope of the invention, it is further conceivable that, if the brake signal is interrupted, a termination process is carried out in which the recuperative control parameter and / or the disturbance variable determination are reduced as a function of a predetermined termination function. The termination function can preferably be a linear function. The interruption of the brake signal can be attributed, for example, to the driver of the vehicle interrupting an actuation of the brake pedal during the functional braking process. This allows the functional braking process to be deactivated and a braking torque to be reduced to zero Nm as quickly as possible, but still just unnoticeable for the driver. This allows the vehicle to be stopped without delay in order to improve safety in the respective driving situation.

[0025] According to a further aspect of the invention, a computer program product is provided. The computer program product comprises instructions which, when executed by a control unit, cause the control unit to execute a method according to the invention.

[0026] Thus, a computer program product according to the invention brings with it the same advantages as have already been described in detail with reference to a method according to the invention. The method can in particular be a computer-implemented method. The computer program product can be implemented as computer-readable instruction code. Furthermore, the computer program product can be stored on a computer-readable storage medium such as a data disk, a removable drive, a volatile or non-volatile memory, or a built-in memory / processor. Furthermore, the computer program product can be provided or made available in a network such as the Internet, from which it can be downloaded by a user or executed online as needed. The computer program product can be implemented both by means of software and by means of one or more special electronic circuits, i.e.be implemented in hardware or in any hybrid form, i.e. using software components and hardware components.

[0027] According to a further aspect of the invention, a vehicle is provided. The vehicle has at least one wheel and a system for braking the wheel to a standstill. The system includes an electric motor. Furthermore, the vehicle has a control unit for executing a method according to the invention.

[0028] Thus, a vehicle according to the invention provides the same advantages as those already described in detail with reference to a method according to the invention and / or a computer program product according to the invention. Furthermore, the vehicle may comprise one or more wheel brakes.

[0029] The modules of the control unit, i.e., in particular the observer module, the target variable module, the correction module, and / or the control module, can be implemented separately from one another or at least partially interconnected. For example, the modules can be formed by memory areas, electronic circuits, and / or, in particular, programmed electronic components of the control unit. Furthermore, the control unit can be configured to execute the computer program product.

[0030] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination. They show schematically: Fig. 1 a control unit when carrying out a method according to the invention, Fig. 2 a braking trajectory in the finalization section of a functional braking process in the method, Fig. 3 a vehicle according to the invention with the control unit, Fig. 4 a permissible range for a target size determination in the method.

[0031] In the following description of some embodiments of the invention, the same reference numerals are used for the same technical features even in different embodiments.

[0032] Fig. Figure 1 shows a control unit 20 executing a method 100 according to the invention for controlling a system 10 for braking a vehicle 1 according to the invention to a standstill in a first exemplary embodiment. The vehicle 1 is connected to the control unit 20 in Fig. 3 and comprises a system 10 for braking the vehicle 1 to a standstill with an electric motor 11 and two mechanically acting wheel brakes 12 for wheels 2 of the vehicle 1. Preferably, a computer program product is provided which comprises instructions which, when executed by the control unit 20, cause the control unit 20 to carry out the method 100.

[0033] In the method 100, a braking signal 200 is first detected 101 by the control unit 20 of the vehicle 1 to initiate a functional braking process 201 for braking the vehicle 1. The braking signal 200 can be detected, for example, as a function of an actuation of a brake pedal 13 of the vehicle 1. To initiate the functional braking process 201, at least one execution condition 204 is checked. For example, it can be checked whether a driver assistance system is engaged in order to rule out mutual influence between the functional braking process 201 and the driver assistance system. Therefore, execution of the functional braking process 201 is prevented depending on the execution condition 204.

[0034] If the execution of the functional braking process 201 is initiated and / or continued depending on the execution condition 204, a state parameter set 210 of the vehicle 1, which includes a speed parameter 211 of the vehicle 1 and preferably a calculated vehicle mass, is determined 102 by an observer module 21 of the control unit 20. For this purpose, the state parameter set 210 is calculated as a function of sensor signals 31 from a vehicle sensor system 30 of the vehicle 1 and a vehicle model. The vehicle model is preferably stored in the observer module 21. The sensor signals 31 include, in particular, a dynamic parameter of the vehicle 1, a wheel parameter of at least one wheel of the vehicle 1, and / or geographical position data of the vehicle 1.

[0035] Depending on the braking signal 200, a finalization section 202 of the functional braking process 201 is defined 103 to achieve standstill by a setpoint module 22 of the control unit 20. The finalization section 202 is, as in Fig. 2, by dividing the functional braking process 201 into a pre-braking section 203 and the finalization section 202. While in the pre-braking section 203 the braking effect and recuperation are aimed for as high as possible, the finalization section 202 enables comfortable braking to a standstill. For this purpose, the finalization section 202 is defined by a time period t1 depending on the speed parameter 211. The definition 103 of the finalization section 202 can be carried out based on a predefined boundary condition 205. Preferably, the boundary condition 205 includes a minimum speed at the beginning of the finalization section 202, as in Fig. 2, and / or a specification of an acceleration change and / or a maximum speed of the vehicle 1.

[0036] The target variable module 22 further determines 104 at least one pilot control parameter set 220 for specifying a braking trajectory for the vehicle 1 to reach a standstill. The finalization section 202 concludes with the standstill, in particular so that a braking torque at standstill is zero and / or a standstill condition, e.g., in the form of reaching a braking torque to compensate for an incline, is met. The pilot control parameter set 220 is determined 104 as a function of the speed parameter 211 of the state parameter set 210. The pilot control parameter set 220 includes a target vehicle speed 211.1, a target vehicle acceleration, and a target change in the vehicle acceleration, which represents, in particular, the jerk of the vehicle 1. Furthermore, the pilot control parameter set 220 includes a target wheel parameter 222, e.g., in the form of a wheel speed of wheel 2.

[0037] The determination 104 of the pre-control parameter set 220 is carried out in particular as a function of a functional relationship in the form v Veh,Soll = a · t 2 + b · t + c, which shows a curve of the target vehicle speed 211.1 with a parabolic run-out until the standstill is reached. Then, in particular, the relationships v˙Veh,Soll(t)=a⋅t+b=FVerzo¨gerung(t)mVeh and v¨Veh,Soll(t)=a=F˙Verzo¨gerung(t)mVeh. For the parabolic run-out to reach a standstill, it can be assumed that the vehicle 1 is a point mass m Veh idealizable and / or has a rotating inertia. The parabolic outlet is in Fig. 2 shown.

[0038] Furthermore, the method 100 comprises determining 105.1 a first control parameter 230 for controlling the electric motor 11 by a control module 23 of the control unit 20. The determination 105.1 of the first control parameter 230 is carried out as a function of the pilot control parameter set 220, the state parameter set 210, and the sensor signals 31. In particular, the target vehicle speed 211.1, the target vehicle acceleration, and the target change in the vehicle acceleration are taken into account from the pilot control parameter set 220 when determining 105.1 the first control parameter 230. Furthermore, the determination 105.1 of the first control parameter 230 can be carried out as a function of a disturbance variable control 233 to take into account disturbance variables external to the vehicle.

[0039] Subsequently, the method 100 comprises outputting 106 a recuperative control parameter 231 for controlling the electric motor 11 in the finalization section 202 by the control module 23. To determine 105 the recuperative control parameter 231, the recuperative control parameter 231 is previously calculated as a function of a disturbance variable determination 235, in particular to take into account vehicle-internal disturbance variables, and the first control parameter 230 using a summation function 234. For this purpose, the method comprises carrying out 107 the disturbance variable determination 235 as a function of the target wheel parameter 222 and a wheel condition parameter 212 of the wheel 2 by a correction module 24 of the control unit 20. The wheel condition parameter 212 is preferably determined as a function of the sensor signals 31 of the vehicle sensor system 30 at the wheel 2 and using a disturbance variable observer 24.1 of the correction module 24.Furthermore, the disturbance variable determination 235 can be carried out as a function of feedback with the braking signal 200 and / or the first control parameter 230. Preferably, the recuperative control parameter 231 is further output in the pre-braking section 203 taking into account the braking signal 200 and is decoupled from the braking signal 200 in the finalization section 202 by a switching module 26 of the control unit 20.

[0040] As in Fig.4, a permissible range 213 can be specified for the target wheel parameter 222 and / or the wheel condition parameter 212. It is preferably provided that the disturbance variable determination 235 is taken into account when outputting 106 the recuperative control parameter 231 if the target wheel parameter 222 and / or the wheel condition parameter 212 is outside the permissible range 213, and the disturbance variable determination 235 is disregarded when outputting 106 the recuperative control parameter 231 if the target wheel parameter 222 and / or the wheel condition parameter 212 is within the permissible range 213. This allows unnecessary controller interventions to be avoided for comfort reasons.

[0041] Preferably, after the completion of the finalization section 202, a holding process is executed, in which the recuperative control parameter 231 is reduced and a mechanical control parameter 232 for the mechanical wheel brake 12 of wheel 2 is increased. This allows the vehicle to be held stationary without the braking trajectory being influenced by the mechanical control parameter 232. Furthermore, if the braking signal 200 is interrupted, a termination process can be executed, in which the recuperative control parameter 231 and / or the disturbance variable determination 235 are reduced depending on a predetermined termination function.

[0042] The above explanation of the embodiments describes the present invention exclusively within the scope of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention. List of reference symbols 1 vehicle 2 wheels 10 systems 11 Electric motor 12 Wheel brake 13 Brake pedal 20 Control unit 21 Observer module 22 Target size module 23 Control module 24 Correction module 26 Switching module 30 vehicle sensors 31 sensor signals 100 procedures 101 Capture of 200 102 Determining 200 103 Defining 202 104 Determining 220 105 Determining 231 105.1 Determining 230 106 Spending of 231 107 Executing 235 200 brake signal 201 functional braking process 202 Finalization Section 203 Pre-braking section 204 Execution condition 205 Boundary condition 210 State parameter set 211 speed parameters 211.1 Target vehicle speed 212 Wheel condition parameters 213 Area 220 Pre-control parameter set 222 Target wheel parameters 230 first control parameter 231 recuperative control parameter 232 mechanical control parameters 235 Determination of disturbance variables T1 time period QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 196 32 939 A1

[0003]

Claims

[1] Method (100) for controlling a system (10) for braking at least one wheel (2) of a vehicle (1) to a standstill, wherein the system (10) comprises an electric motor (11) for braking the wheel (2), wherein the method (100) comprises: - detecting (101) a braking signal (200) for initiating a functional braking process (201) for braking the vehicle (1) by the system (10), - defining (103) a finalization section (202) of the functional braking process (201) for reaching standstill in dependence on the braking signal (200), - determining (104) at least one pilot control parameter set (220) for specifying a braking trajectory (221) for the vehicle (1) to reach a standstill, wherein the pilot control parameter set (220) comprises a target wheel parameter (222), - carrying out (107) a disturbance variable determination (235) as a function of the target wheel parameter (222) and a wheel state parameter (212) of the wheel (2), - Outputting (106) a recuperative control parameter (231) for controlling the electric motor (11) to brake the wheel (2) in the finalization section (202) as a function of the disturbance variable determination (235) and the pre-control parameter set (220). [2] Method (100) according to claim 1, characterized by that the method (100) comprises: - determining (105.1) a first control parameter (230) for controlling the electric motor (11) as a function of the pre-control parameter set (220), wherein the recuperative control parameter (231) for outputting (106) the recuperative control parameter (231) is calculated as a function of the disturbance variable determination (235) and the first control parameter (230). [3] Method (100) according to claim 1 or 2, characterized by that the method (100) comprises: - Determining (102) a state parameter set (210) of the vehicle (1), which comprises a speed parameter (211) of the vehicle (1), wherein the pilot control parameter set (220) is determined as a function of the speed parameter (211) and the determination (105.1) of the first control parameter (230) is carried out as a function of the state parameter set (210). [4] Method (100) according to one of the preceding claims, characterized by that the state parameter set (210), the wheel state parameter (212) and / or the target wheel parameter (222) is determined as a function of sensor signals (31) of a vehicle sensor system (30) of the vehicle (1). [5] Method (100) according to one of the preceding claims, characterized bythat the wheel state parameter (212) for carrying out (107) the disturbance variable determination (235) is determined using a disturbance variable observer (24.1) and / or using sensor signals (31) of a vehicle sensor system (30) on the wheel (2). [6] Method (100) according to one of the preceding claims, characterized by that a permissible range (213) is specified for the target wheel parameter (222) and / or the wheel condition parameter (212), wherein the disturbance variable determination (235) is taken into account when outputting (106) the recuperative control parameter (231) if the target wheel parameter (222) and / or the wheel condition parameter (212) is outside the permissible range (213). [7] Method (100) according to one of the preceding claims, characterized bythat the definition of the finalization section (202) is carried out on the basis of a predefined boundary condition (205), wherein the boundary condition comprises a minimum speed at the beginning of the finalization section (202) and / or a specification of an acceleration change and / or a maximum speed of the vehicle (1). [8] Method (100) according to one of the preceding claims, characterized by that the finalization section (202) is defined by a subdivision of the functional braking process (201) into a pre-braking section (203) and the finalization section (202), wherein the recuperative control parameter (231) is output in the pre-braking section (203) taking into account the braking signal (200) and in the finalization section (202) decoupled from the braking signal (200). [9] Method (100) according to one of the preceding claims, characterized bythat after the completion of the finalization section (202), a holding process is carried out in which the recuperative control parameter (231) is reduced and a mechanical control parameter (232) for a mechanical wheel brake (12) of the wheel (2) is increased. [10] Method (100) according to one of the preceding claims, characterized by that when the brake signal (200) is interrupted, a termination process is carried out in which the recuperative control parameter (231) and / or the disturbance variable determination (235) are reduced as a function of a predetermined termination function. [11] Computer program product comprising instructions which, when executed by a control unit (20), cause the control unit (20) to carry out a method (100) according to one of the preceding claims. [12] Vehicle (1) comprising at least one wheel (2), a system (10) for braking the wheel (2) to a standstill with an electric motor (11), a control unit (20) for executing a method (100) according to one of claims 1 to 10.

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