Dynamic timing control of brake control systems with multiplex operation

Abstract

Control unit (120) for a brake system (100, 200) of a vehicle, wherein the brake system (100, 200) has a plunger (104) and a cylinder (111, 204) in which the plunger (104) can be moved, via which a plurality of setpoint pressures can be sequentially set in a corresponding plurality of wheel brakes (114), wherein a corresponding plurality of brake valves (113) is assigned to the plurality of wheel brakes (114); wherein the control unit (120) is configured - to cause a first brake valve (113) of the plurality of brake valves (113) to open while the other brake valves (113) of the plurality of brake valves (113) are closed; - to cause the plunger (104) to move in order to set a first target pressure from the plurality of target pressures for a first wheel brake (114) from the plurality of wheel brakes (114) that is assigned to the first brake valve (113); - to check whether the plunger (104) manages to set the first target pressure within a predetermined time slice; - to determine an initial time slice that the plunger (104) needs to set the initial target pressure; and - to close the first brake valve (113) after the first time slice has elapsed; characterized in that the control unit (120) is further configured, - to determine whether the first time slice has a length that corresponds to or exceeds a predetermined time slice threshold; and - to degrade the sequential setting of the plurality of set pressures in the plurality of wheel brakes (114) if the length of the first time slice corresponds to or exceeds the predetermined time slice threshold.

Description

[0001] The invention relates to a braking system for a motor vehicle. In particular, the invention relates to the control of braking systems with multiplex operation.

[0002] Currently, brake systems are being investigated that allow decoupling between the pedal plunger of a brake pedal and the plunger of a master brake cylinder, thus providing brake-by-wire functionality. This is particularly advantageous for efficiently implementing intelligent braking functions such as ABS (Anti-lock Braking System), ASR (Anti-Slip Regulation), ASC (Automatic Stability Control), and / or ESP (Electronic Stability Program).

[0003] DE 10 2010 008 033 A1 discloses a braking system with a brake booster, the piston-cylinder system of which is driven mechanically or hydraulically by an electric motor, in particular by means of transmission means, wherein at least one working chamber of the piston-cylinder system is connected to at least two wheel brakes via hydraulic lines and, among other things, a control device calculates the respective pressure in the wheel brakes by means of a pressure model and transmits the calculated pressure values ​​to at least an ABS / ESP controller and a pressure control device, wherein the pressure control device controls at least the 2 / 2-way switching valves and the electric motor and a prioritization device selects a wheel at least on the basis of the data transmitted by the ABS / ESP controller and transmits this to the pressure control device.

[0004] Furthermore, the closest prior art, DE 10 2009 008 941 A1, describes a brake system with a brake booster, the piston-cylinder system of which is driven by an electric motor and has at least one working chamber which is connected to at least one wheel brake via hydraulic lines, wherein a 2 / 2-way switching valve is assigned to each wheel brake, by means of which the hydraulic connecting line between the wheel brake and the working chamber of the piston-cylinder system can be closed, wherein the electric motor and the switching valves are controlled by a control device.

[0005] However, despite the decoupling between the brake pedal and the master cylinder, the braking system of the invention should still ensure a reliable provision of the basic and, if possible, also the intelligent braking functions. The present document therefore addresses the technical problem of increasing the reliability of brake-by-wire braking systems.

[0006] One aspect describes a control unit for a vehicle's braking system. The vehicle could be, for example, a motor vehicle (such as an automobile). The braking system may include a plunger rigidly coupled to a piston in a cylinder. The plunger can be moved by an electric motor. The movement of the plunger increases or decreases pressure. The cylinder may be a master brake cylinder or a dedicated plunger cylinder. The control unit can be configured to generate control signals for the electric motor to initiate movement of the plunger. In particular, the control unit can be configured to sequentially set a multitude of target pressures in a corresponding multitude of wheel brakes of the vehicle by appropriately controlling the electric motor. A corresponding multitude of brake valves are typically assigned to each of the wheel brakes.

[0007] The control unit can be configured to open a first brake valve among a set of brake valves, while the other brake valves remain closed. Opening the first brake valve allows the first target pressure to be set in the first wheel brake. To achieve this, the control unit can be configured to move the plunger (e.g., using an electric motor) to set the first target pressure for the first wheel brake. The first wheel brake is then assigned to the first brake valve. Opening the first brake valve creates a hydraulic connection between the master cylinder and the first wheel brake, allowing the pressure in the first wheel brake to be adjusted.

[0008] By sequentially opening one brake valve at a time, the control unit can be configured to sequentially set the multiple target pressures in the multiple brake valves. This procedure can be described as multiplex operation of the brake system. Specifically, the control unit can be configured to cause one of the multiple brake valves to open while the other brake valves remain closed. Furthermore, the control unit can be configured to cause the plunger to move in order to set the target pressure for the wheel brake associated with the currently open brake valve.

[0009] Furthermore, the control unit can be configured to check whether the plunger manages to reach the initial target pressure within a predetermined time interval. In other words, the control unit can be configured to verify whether, immediately after the predetermined time interval has elapsed, the pressure in the first wheel brake corresponds to the initial target pressure. For this purpose, the control unit can be configured to receive signals from a primary pressure sensor, which is configured to measure the pressure in the first wheel brake. The braking system can include multiple pressure sensors for the corresponding number of wheel brakes. Alternatively or additionally, the control unit can be configured to determine the pressure of a wheel brake based on the plunger's position and a hydraulic model. Thus, verification that the target pressure has been reached in a wheel brake can also be performed without an explicit pressure measurement by a pressure sensor.

[0010] Checking the pressure in the first wheel brake at the end of the first time slot allows the control unit to determine whether the plunger's dynamics (especially those of the electric motor) are sufficient to operate the braking system in multiplex mode. If it is determined that the dynamics are insufficient, the control unit can be configured to take measures to ensure continued reliable operation of the braking system.

[0011] For example, the control unit can be configured to determine an initial time slice that the plunger needs to set the initial target pressure. This initial time slice can be longer or shorter than the predetermined time slice. Furthermore, the control unit can be configured to close the first brake valve after the initial time slice has elapsed. The control unit can then initiate the opening of the next brake valve to set the target pressure of the next wheel brake. This next brake valve can remain open for a time slice sufficient to set the target pressure for the next wheel brake. This process can be repeated sequentially. Consequently, the control unit can be configured to use different time slices for setting the pressures of the different wheel brakes.In particular, the control unit may be configured to operate the braking system in a “handshake” mode, in which the setting of the next wheel brake takes place directly after the target pressure of a previous wheel brake has been set.

[0012] The control unit can be configured to determine whether the first time slice has a length equal to or exceeding a predetermined time slice threshold. Furthermore, the control unit can be configured to degrade the sequential setting of multiple target pressures in multiple wheel brakes if the length of the first time slice equals or exceeds the predetermined time slice threshold. Degrading the sequential setting or multiplex operation can, for example, result in the pressure being set simultaneously in two or more wheel brakes (as described below).

[0013] If the plunger fails to set the first target pressure within the predetermined time slot, the control unit can be configured to degrade the sequential setting of the multiple target pressures in the multiple wheel brakes. This can be achieved by causing at least two of the multiple wheel brakes to be set to a common target pressure simultaneously. To this end, the control unit can be configured to open the first and one of the second brake valves in the multiple brake valves, while the other brake valves in the multiple brake valves remain closed. Furthermore, the control unit can be configured to move the plunger to set the common target pressure for the first and one of the second wheel brakes in the multiple wheel brakes, with the second wheel brake being assigned to the second brake valve.

[0014] By combining the settings of the wheel brakes, the multiplex operation can be gradually degraded until finally all wheel brakes are set simultaneously.

[0015] Gradual degradation of multiplex operation can ensure increased availability of braking functions.

[0016] The multiple wheel brakes can include two or more front brakes and two or more rear brakes. As an intermediate stage of degradation, the control unit can be configured to cause the front brakes to be simultaneously set to a first common target pressure, and the rear brakes to be simultaneously set to a second common target pressure. Separate adjustment of the rear and front brakes prevents overbraking of the rear axle.

[0017] Furthermore, the control unit can be configured to cause all brake valves of the multitude of brake valves to open and to cause the plunger to move in order to set the common target pressure for all wheel brakes of the multitude of wheel brakes.

[0018] The control unit can be configured to increase the length of the predetermined time slice. The length of the predetermined time slice can depend on the degree of degradation of the sequential adjustment. In particular, if the number of wheel brake groups that need to be adjusted sequentially is reduced, the length of the time slice available for adjusting each wheel brake group can be increased.

[0019] According to another aspect, a braking system is described that includes the control unit described in this document.

[0020] According to another aspect, a method for sequentially setting a plurality of target pressures in a corresponding plurality of wheel brakes is described. The method includes opening a first brake valve of a plurality of brake valves assigned to the corresponding plurality of wheel brakes, while the other brake valves of the plurality are closed. Furthermore, the method includes moving a plunger in a cylinder (e.g., a master cylinder or a plunger cylinder) to set a first target pressure from the plurality of target pressures for a first wheel brake from the plurality of wheel brakes assigned to the first brake valve. In addition, the method includes verifying whether the first target pressure can be set within a predetermined time slice. As already explained above, the pressure verification can also be performed using a hydraulic model by checking the plunger position.Consequently, the procedure can include checking whether the plunger can be moved sufficiently far within the predetermined time slice to establish the initial target pressure. In other words, the initial target pressure can correspond to an initial target displacement of the plunger (via a predetermined hydraulic model), and the procedure can include checking whether the plunger can travel this initial target displacement within the predetermined time slice. This applies analogously to the multitude of wheel brakes for which a corresponding multitude of target displacements may exist.

[0021] The method for sequentially setting a multitude of target pressures in a corresponding multitude of wheel brakes further comprises determining a first time slice required by the plunger to set the first target pressure and closing the first brake valve after the first time slice has elapsed. It also includes determining whether the first time slice has a length that corresponds to or exceeds a predetermined time slice threshold and degrading the sequential setting of the multitude of target pressures in the multitude of wheel brakes if the length of the first time slice corresponds to or exceeds the predetermined time slice threshold.

[0022] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor and thereby execute the procedure described in this document.

[0023] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0024] The invention will now be described in more detail using exemplary embodiments. Fig. 1 an exemplary braking system for a motor vehicle; and Fig. 2 another exemplary braking system for a motor vehicle.

[0025] Fig. Figure 1 shows an exemplary braking system 100 for a motor vehicle (e.g., for a single-track motor vehicle such as a motorcycle or for a two-track motor vehicle such as an automobile). The braking system 100 includes a brake pedal 101 with which a driver of the vehicle can actuate the wheel brakes 114 of the vehicle. Fig. Figure 1 shows four wheel brakes 114 for the four wheels of the vehicle as an example. An auxiliary piston 102 is moved via the brake pedal 101. The deflection of the brake pedal 101 and / or the force with which the brake pedal 101 is actuated can be detected by a pedal force simulator 106. The auxiliary piston 102 is separated from the plunger 104 and the master brake cylinder 111 by a gap 103, so that in normal operation the plunger 104 is not actuated directly by the brake pedal 101, but is moved by means of a plunger motor 105. On the other hand, the gap 103 is designed such that in emergency operation (e.g., in the event of a power failure or defect of the plunger motor 105) the brake pedal 101 can move the plunger 104 directly via the auxiliary piston 102. In normal operation, the pedal force simulator 106 is also used to build up a suitable counterforce for the brake pedal 101 in order to give the driver a typical brake pedal feel.

[0026] The plunger motor 105 can be controlled based on information acquired by the pedal force simulator 106 (e.g., deflection of the brake pedal 101 and / or the force with which the brake pedal 101 is actuated). The plunger motor 105 can be, for example, an electric motor with a spindle drive and / or a brushless electric motor. Pistons 109 and 110 in the master brake cylinder 111 are moved via the plunger 104. In the example shown, this is a tandem master brake cylinder (THZ) 111 with a pushrod piston 109 (which is coupled to the plunger 104) and a floating piston 110.

[0027] Decoupling the plunger 104 and the brake pedal 101 allows the individual wheel brakes 114 of the vehicle to be controlled separately (especially sequentially) by the plunger 104 and the master brake cylinder 111. Each of the different wheel brakes 114 is assigned to a wheel brake valve 113 (e.g., a 2 / 2-way wheel brake valve). The wheel brake valves 113 can be controlled such that at a specific time or period (or time slice), one wheel brake valve 113 is open while all other wheel brake valves 113 are closed. During this period, the pressure for the wheel brake 114 assigned to the open wheel brake valve 113 can then be adjusted via the master brake cylinder 111 by appropriately displacing the plunger 104.

[0028] By opening a different wheel brake valve 113 at a time, the pressures for the various wheel brakes 114 of the vehicle can be set sequentially. A highly dynamic plunger motor 105 can be used to move the plunger 104. The sequential adjustment of the pressures in the various wheel brakes 114 can be referred to as multiplex operation. Multiplex operation enables the efficient provision of intelligent braking functions such as ABS (Anti-lock Braking System), ASR (Anti-Slip Regulation), ASC (Automatic Stability Control), and / or ESP (Electronic Stability Program).

[0029] Fig. Figure 1 further shows a simulator shut-off valve 107 (e.g., a 2 / 2-way wheel brake valve) through which the flow of brake fluid from the pedal force simulator 106 can be diverted to the reservoir 108. When the simulator shut-off valve 107 is open, no hydraulic pressure is built up on the pedal force simulator 106 by the auxiliary piston 102, since the brake fluid can flow to the reservoir 108 at nearly no pressure. In the de-energized state, the simulator shut-off valve 107 is typically open.

[0030] In other words, Fig. Figure 1 shows an electro-hydraulic brake system 100 that provides brake-by-wire functionality and enables multiplex control of the vehicle's wheel brakes 114. The depicted system 100 comprises a simulator shut-off valve 107 and four wheel valves 113 for the vehicle's four wheel brakes 114. The brake system 100 may also include additional valves that can perform specific additional tasks, such as enabling free stroke for brake recuperation (in hybrid vehicles) and / or supply valves (fluid transfer from the simulator circuit to the front axle circuit). However, these are typically not required for pure multiplex control.

[0031] The in Fig. The brake system 100 shown typically includes a control unit 120, which is configured to receive various sensor signals 121 and to generate control signals 122 based on the received sensor signals 121. For example, the control unit 120 can receive sensor signals 121 from the pedal force simulator 106 (e.g., information regarding the force with which the brake pedal 101 is actuated and / or regarding the deflection of the brake pedal 101). Furthermore, the control unit 120 can be configured to generate control signals 122 for controlling the plunger motor 105 (e.g., depending on the sensor signals 121 received from the pedal force simulator 106). One or more sensors that measure the movement of the brake pedal 101 can be attached to the actuation point. This is, for example, Fig. 2 shown by the pedal travel sensor 201. The pedal travel sensor 201 is set up to measure the deflection of the brake pedal 101.

[0032] At the in Fig. In the brake system 100 shown, the pedal force simulator 106 is supplied via auxiliary piston 102. The plunger motor 105 acts on the primary piston 109 of the THZ 111, which is rigidly coupled to the plunger 104. Alternatively, a "parallel brake system" can be used, in which the motor 105 actuates its own plunger in a separate cylinder. In this case, the auxiliary piston 102 and the gap 103 would be omitted. The fluid from the THZ 111 would then be switched to the simulator 106 or to the wheel circuits 113 and 114 via switching valves.

[0033] Fig. Figure 2 shows an exemplary parallel braking system 200 in which the motor 105 moves or actuates a plunger in a plunger cylinder 204. The braking system 200 includes isolating valves 202 and switching valves 203 to switch between the master brake cylinder circuit (which includes the master brake cylinder 111) and the plunger circuit (which includes the plunger cylinder 204). In the de-energized state, the valves 202 and 203 are switched such that the wheel brakes 114 are actuated from the master brake cylinder 111. The plunger circuit (in particular the plunger cylinder 204) and the pedal force simulator 106 are then deactivated.

[0034] In brake-by-wire mode, the fluid from the THZ 111 is shut off from the wheel circuits by the isolating valves 202. The fluid from the primary circuit (of the pushrod piston 109) is directed through the simulator shut-off valve 107 to the cylinder of the pedal force simulator 106. This allows the pedal force simulator 106 to determine the force with which the brake pedal 101 was actuated. Furthermore, when the brake pedal 101 is actuated, the pedal force simulator 106 draws brake fluid from the THZ 111 and generates a corresponding counterforce to create a familiar brake pedal feel. Without such absorption of the brake fluid by the pedal force simulator 106, the brake pedal 101 could not be moved, which would lead to uncertainty for the driver (even though the plunger motor 105 would brake the wheel brakes 114 in response to the actuation of the brake pedal 101 and based on a measurement of the force of the actuation of the brake pedal 101).

[0035] The fluid from the plunger circuit (i.e., in particular from the plunger cylinder 204) is directed to the wheel brakes 114 via the switching valves 203. Selective activation of individual wheel brakes 114 in multiplex operation can be achieved via the wheel valves 113, as described above.

[0036] Fig. Figure 2 further shows an example pedal travel sensor 201, which is configured to detect the deflection of the brake pedal 101. It also shows Fig. 2. An inlet valve 205 allows brake fluid from reservoir 108 to enter the plunger cylinder 204. It should also be noted that the brake system 200 may include further valves, which can be used, for example, to perform special diagnostics. However, these are typically not required for multiplex control.

[0037] As explained above, in multiplex operation, when the brake control system intervenes, each wheel brake 114 is individually and cyclically hydraulically controlled one after the other. For this purpose, the pressure in (n-1) of (n) wheel brakes 114 is locked in by the valves 113, and the valve 113 of only one wheel brake 114 is opened, and the target pressure of this wheel brake is set by the hydraulic plunger 104 (e.g., n=4).

[0038] In multiplex operation, a specific time slice or period is typically reserved for each wheel brake 114 to set the target pressure. This can be problematic if, due to dynamic losses, the time slice reserved for a wheel brake 114 is insufficient to bring that wheel brake 114 to the target pressure. Such dynamic losses can result, for example, from a degradation of dynamics, such as a voltage-dependent reduction in current draw. For instance, the vehicle's energy management system may reduce the electrical energy available to the vehicle's various electrical consumers if the on-board voltage drops below a predefined threshold. This can result in the plunger motor 105 losing dynamics and therefore no longer being able to set the target pressure of a wheel brake 114 within the specified or predetermined time slice.

[0039] The control unit 120 can be configured to receive sensor signals 121 from pressure sensors that are configured to measure the pressure at the assigned wheel brakes 114. The pressure sensor for a wheel brake 114 can be located between the wheel valve 113 and the wheel brake 114. Furthermore, the control unit 120 can be configured to monitor whether the plunger 104 manages to travel the target distance or set the target pressure for the respective wheel brake 114 within the specified time period. Consequently, the control unit 120 can be configured to monitor whether the plunger motor 105 can move the plunger 104 quickly enough to actuate the wheel brakes 114 in multiplex operation.

[0040] If it is determined that the plunger 104 is unable to actuate the wheel brakes 114 in multiplex mode, the control unit 120 may be configured to deactivate multiplex mode (at least partially) and actuate the wheel brakes (at least partially) simultaneously. This typically results in control functions (e.g., intelligent braking functions such as ABS, etc.) that utilize multiplex mode also being at least partially deactivated.

[0041] For example, the control unit 120 can be configured to downgrade from full multiplex operation, in which all wheel brakes 114 are controlled separately, to reduced multiplex operation, in which, for example, the front and rear brakes 114 are controlled together. This doubles the time available for controlling each pair of wheel brakes. Furthermore, separate control of the front and rear brakes 114 still allows for targeted brake force distribution between the front and rear axles. In particular, it ensures that the rear axle is not overbraked.

[0042] Alternatively or additionally, the control unit 120 can be configured to operate the multiplex wheel brake control with a "handshake" between the plunger actuator (e.g., the motor 105) and the multiplex timing control. In particular, the multiplex operation can be configured such that the pressure control at one wheel brake 114 is only switched to the next wheel brake 114 once the plunger 104 has correctly actuated the current wheel brake 114 and set the correct target pressure. This "handshake" operation allows the length of a time slice for setting the target pressure of a wheel brake 114 to be adapted to the dynamics of the plunger 104 (and the motor 105). This ensures that the pressure in each wheel brake 114 is set correctly.

[0043] On the other hand, extending the time slices for setting the target pressure leads to reduced dynamics for controlling braking functions, such as the intelligent braking functions mentioned above. To ensure sufficient dynamics for controlling such braking functions, a time slice threshold can be set. If the handshake operation results in a time slice that is equal to or longer than the time slice threshold, the multiplex operation, as described above, can be reduced or completely deactivated. This typically results in some braking functions being restricted or deactivated.

[0044] The control unit 120 can be configured to inform the driver of the vehicle (e.g. via a display) that the multiplex operation and / or certain braking functions have been restricted or deactivated.

[0045] By using a "handshake" operation, the availability of braking functions can be increased, as the braking functions can continue to operate with a slower multiplex (until the time-slice threshold is reached or exceeded). Furthermore, by partially or completely deactivating the multiplex operation, it can be ensured that no undesirable effects occur during brake control due to incorrect hydraulic control of the wheel brakes 114.

Claims

[1] Control unit (120) for a brake system (100, 200) of a vehicle, wherein the brake system (100, 200) has a plunger (104) and a cylinder (111, 204) in which the plunger (104) can be moved, via which a plurality of setpoint pressures can be sequentially set in a corresponding plurality of wheel brakes (114), wherein a corresponding plurality of brake valves (113) is assigned to the plurality of wheel brakes (114); wherein the control unit (120) is configured - to cause a first brake valve (113) of the plurality of brake valves (113) to open while the other brake valves (113) of the plurality of brake valves (113) are closed; - to cause the plunger (104) to move in order to set a first target pressure from the plurality of target pressures for a first wheel brake (114) from the plurality of wheel brakes (114) that is assigned to the first brake valve (113); - to check whether the plunger (104) manages to set the first target pressure within a predetermined time slice; - to determine an initial time slice that the plunger (104) needs to set the initial target pressure; and - to close the first brake valve (113) after the first time slice has elapsed; characterized by , that the control unit (120) is further configured, - to determine whether the first time slice has a length that corresponds to or exceeds a predetermined time slice threshold; and - to degrade the sequential setting of the plurality of set pressures in the plurality of wheel brakes (114) if the length of the first time slice corresponds to or exceeds the predetermined time slice threshold. [2] Control unit (120) according to claim 1, wherein if the plunger (104) fails to set the first target pressure in the predetermined time slice, the control unit (120) is configured to degrade the sequential setting of the plurality of target pressures in the plurality of wheel brakes (114) by causing at least two of the plurality of wheel brakes (114) to be set to a common target pressure simultaneously. [3] Control unit (120) according to claim 2, comprising causing at least two of the plurality of wheel brakes (114) to be simultaneously set to a common target pressure. - to cause the first and a second brake valve (113) of the plurality of brake valves (113) to open; and - to cause the plunger (104) to move in order to set the common target pressure for the first and a second wheel brake (114) from the plurality of wheel brakes (114), wherein the second wheel brake (114) is assigned to the second brake valve (113). [4] Control unit (120) according to one of claims 2 to 3 , wherein - the control unit (120) is configured to increase the length of the predetermined time slice; and - where the length of the predetermined time slice depends on a degree of degradation of the sequential setting. [5] Control unit (120) according to one of claims 2 to 4, wherein - the multitude of wheel brakes (114) includes front brakes and rear brakes; and - the control unit (120) is set up to cause the front brakes to be set simultaneously to a first common target pressure, and the rear brakes to be set simultaneously to a second common target pressure. [6] Control unit (120) according to any one of claims 2 to 5, wherein the control unit (120) is configured, - to cause all brake valves (113) of the plurality of brake valves (113) to open; and - to cause the plunger (104) to move in order to set the common target pressure for all wheel brakes (114) from the plurality of wheel brakes (114). [7] Control unit (120) according to a previous claim, wherein the control unit (120) is configured in a sequential manner - to cause one of the brake valves (113) of the plurality of brake valves (113) to open while the other brake valves (113) of the plurality of brake valves (113) are closed; and - to cause the plunger (104) to move in order to set the target pressure from the multitude of target pressures for the wheel brake (114) from the multitude of wheel brakes (114) that is assigned to the brake valve (113) that is open in each case. [8] Method for sequentially setting a plurality of target pressures in a corresponding plurality of wheel brakes (114), wherein the method comprises - Opening of a first brake valve (113) of a plurality of brake valves (113) which is assigned to the corresponding plurality of wheel brakes (114), while the other brake valves (113) of the plurality of brake valves (113) are closed; - Moving a plunger (104) to set a first setpoint pressure from the plurality of setpoint pressures for a first wheel brake (114) from the plurality of wheel brakes (114) that is associated with the first brake valve (113); and - Check whether the plunger (104) can be moved sufficiently within a predetermined time slice to set the first target pressure; - Determining an initial time slice required by the plunger (104) to set the initial target pressure; and - Closing of the first brake valve (113) after the first time slice has elapsed; characterized by , that the procedure further includes, - Determine whether the first time slice has a length that is equal to or exceeds a predetermined time slice threshold; and - Degrading the sequential setting of the plurality of set pressures in the plurality of wheel brakes (114) when the length of the first time slice corresponds to or exceeds the predetermined time slice threshold.

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