Dynamic braking method consisting in braking a rear wheel of the vehicle in the event of a failure of the hydraulic braking system

Abstract

The invention relates to a dynamic braking method that can be used in a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate during the driving of the vehicle and a parking brake having an electromechanical actuating unit, the method consisting in braking a rear wheel of the vehicle in the event of a failure of the hydraulic braking system. The method consists in first placing the electromechanical unit in a dynamic state by taking up the functional clearances of the parking brake, predicting a braking need expressed by the driver on the brake pedal, and then applying a clamping force to the parking brake which is in its dynamic state when a braking need is expressed by the driver.

Description

Dynamic braking method consisting of braking a rear wheel of the vehicle in the event of failure of the hydraulic braking system

[0001] The invention relates to the technical field of electric parking brakes, and in particular the field of the use of electric parking brakes during dynamic braking.

[0002] As described in document US 7,744,166, a parking brake is implemented electrically and / or automatically by an electromechanical unit, also called an electric actuator, associated with one or more of the rear wheels of the vehicle. Thus, a user of the vehicle wishing to engage the parking brake simply needs to press a push button, located for example on the dashboard near the steering wheel, to trigger or terminate the application of the parking brake around the wheel of the vehicle.

[0003] Also known, in particular from document US 7,721,853, is a monobloc brake housing which contains both a hydraulic unit for braking while driving and an electromechanical unit for parking braking. By definition, these two units are not designed to operate at the same time, but their integration into a single housing facilitates assembly and saves space.

[0004] It is known that the presence of an electrically controlled parking brake makes it possible to use the electromechanical unit, normally dedicated to parking braking, as an emergency braking system in the event of a failure of the hydraulic unit. The driver can thus stop the vehicle using the electric parking brake control button. This feature is a common requirement of car manufacturers. The driver must be able to stop the vehicle using the electric parking brake control button that applies to the rear wheels.

[0005] To this end, an algorithm is implemented which is illustrated by the, in which it can be seen that from an initial operating state 1 of application of an emergency braking application by the electromechanical unit, the application of the brake is stopped in the event of slippage greater than a first predetermined slippage threshold, by moving to a stop state 2. From this stop state 2, if the slippage continues to increase and passes above a second slippage threshold, the application is released by moving to a release state 3. From this release state 3, if the slippage falls below the second slippage threshold, the application is maintained by moving to a hold state 4. From this hold state 4, if the slippage falls below a relocking threshold, then the application returns to state 1. It is noted that three parameters are necessary for the execution of this algorithm: the first threshold, the second threshold and the relocking threshold.The measurements needed for this execution are the wheel speeds, which allow the level of slip to be measured.

[0006] This well-known multi-threshold braking method is called RWU, for "Rear Wheel Unlocker." It involves using the rear wheel parking brake to brake them without locking them. In short, if a wheel locks, the brake is released to unlock the wheel, then re-tightened, and so on.

[0007] In electrical terms, the execution of the method results in the physical quantities of electric current 5 and control signal 6 illustrated in the, compared to the activation of the braking by the driver 6 and the clamping force 7 applied to the brake by the electromechanical unit.

[0008] The actuator thus passes through three states: release 6a, tightening 6b, loosening 6c.

[0009] This method is inspired by the hydraulic anti-lock braking system marketed under the ABS brand name, but differs in that it uses electrical control of the brake motor. It requires operational operation of the speed sensors of at least one front wheel and both rear wheels.

[0010] To address situations where no front wheel speed sensor is operational or at least one rear wheel speed sensor is out of order, an incremental braking force braking method has been proposed.

[0011] In all cases, the desired goal is achieved, namely stopping the vehicle, but the braking performance is limited and a deceleration of between 0.15g and 0.3g is obtained.

[0012] Additionally, RWU or incremental force braking methods have some other drawbacks, which are not prohibitive but leave room for improvement.

[0013] First of all, deceleration is not adjustable. It depends mainly on road conditions and the weight of the vehicle.

[0014] As a corollary, wheel lock situations occur quite frequently during such braking, due to the sudden and relatively late increase in the clamping force, which primarily seeks maximum braking to achieve optimal safety.

[0015] Thus, on the, where we see the evolution as a function of time of:- the electrical voltage 8 supplying the controllers of the electric motors of the electromechanical unit,- the deceleration 9 in m / s 2,- the command 10 for applying the parking brake,- the electric current 11 applied to the electric motor of the left rear wheel,- the electric current 12 applied to the electric motor of the right rear wheel,- the command 13 of the electric motor of the left rear wheel,- the command 14 of the electric motor of the right rear wheel,- the state 15 of the actuator of the brake of the left rear wheel,- the state 16 of the actuator of the brake of the right rear wheel,- the speed 17 of the left front wheel,- the speed 18 of the right front wheel,- the speed 19 of the left rear wheel,- the speed 20 of the right rear wheel,- the slip coefficient 21 of the left rear wheel,- the slip coefficient 22 of the right rear wheel,

[0016] We note that the rear wheel rotation speeds 19 and 20 are zero for a relatively long time due to the slip coefficients 21 and 22 being too high. The effectiveness of the emergency braking is therefore not always optimal.

[0017] This results in imperfect vehicle stability, or at the very least, uncomfortable stability for its passengers. Similarly, braking precision is lacking, since it is by definition always at maximum.

[0018] As a result, the electromechanical unit is currently only used to perform emergency braking when the hydraulic unit is out of service. Braking during normal driving is not comfortable enough to be considered.

[0019] There is therefore a need for an emergency braking solution in the event of a malfunction of the hydraulic unit, which provides a braking mode adjusted to the driving circumstances, i.e. which responds proportionately to the braking requests expressed by the driver when he presses the brake pedal.

[0020] Preferably, in order to avoid causing instabilities, the emergency brake should:- adapt the braking force to the slippage of the roads,- manage each wheel individually- take into account the vehicle speed, lateral acceleration and the friction coefficient of the road.

[0021] Preferably, the emergency brake should allow a driver to drive their vehicle with a defective hydraulic braking system to a repair shop. To this end, deceleration should be moderated depending on the pressure on the brake pedal and, for example, the modulation of deceleration should depend on the position of the brake pedal. In addition, the responsiveness of the electromechanical unit should be improved, so that the brake reaction time is not too long, compared to when the hydraulic unit commands it.

[0022] Finally, when necessary, the overall deceleration of the vehicle should achieve better performance, for example 0.5g instead of peaking at 0.3g.

[0023] Another object of the invention is to be able to obtain this adjusted braking solution by using a single-box brake containing both a hydraulic unit for driving braking and an electromechanical unit for parking braking.

[0024] The invention mainly relates to a dynamic braking method applicable to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, the method consisting of braking a rear wheel of the vehicle in the event of a failure of the hydraulic braking system, characterized in that it consists of first placing the electromechanical unit in a dynamic state by consuming the functional clearances of the parking brake, in anticipation of a braking need expressed by the driver on the brake pedal, then applying a clamping force to the parking brake in its dynamic state when a braking need is expressed by the driver.

[0025] In a particular embodiment of the invention, the dynamic state consists of: - if the parking brake is released: recalibrating the electromechanical unit by applying a temporary increase in current to its electric motor, then releasing the parking brake by returning to the initial current for a release period, - if the parking brake is activated, releasing the parking brake for a release period, - if the parking brake is already requested as an emergency brake because the process has already started during a previous cycle, releasing for a release period.

[0026] In a particular embodiment of the invention, the application of the clamping force consists of:- recovering a braking request from the driver in the form of a clamping force setpoint determined as a function of the way in which the driver pressed said pedal,- modifying the electrical power supply to the motor of the electromechanical unit to increase the clamping force of the parking brake, firstly achieved by applying a predetermined increase in electrical current to the motor, then by increasing the clamping force by brief successive applications of current each having a predetermined duration.

[0027] According to other optional characteristics of the method, taken alone or in combination:– the predetermined increase in electric current to the motor is 1 A,– the predetermined duration of the brief applications is 50 ms,– the number of successive current applications is limited to a value between 6 and 12, preferably 9, for the dynamic mode and between 3 and 7 for the static mode.

[0028] The main advantages of the invention are as follows:– modulation of the braking force of the electric parking brake according to the driver's request on the brake pedal. It is no longer a question of activating the parking brake with a button. The driver brakes as if his main braking system were still operational, and depending on the travel of the brake pedal and / or the hydraulic pressure, the braking force of the parking brake is adjusted.– increased precision thanks to a reduction in the brake reaction time, taking into account the position of the brake pedal and an improvement in the release thanks to step-by-step actions. All while maintaining the principle of wheel speed control to ensure the stability of the vehicle.– adaptation to automatic parking brake systems of different types while guaranteeing good braking performance: bite, linearity, comfort and controllability.

[0029] In other words, the invention proposes to detect the failure of the hydraulic system to reduce the functional clearances in order to guarantee a faster response time, before creating a braking force of the parking brake proportional to the driver's pressure on the brake pedal. This reduced clearance is maintained as long as the function is active and the hydraulic system is faulty.

[0030] The invention also relates to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, which comprises a brake pedal travel sensor, an electronic stability control computer and means for implementing the method described above. Brief description of the figures

[0031] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings in which:

[0032] illustrates a known algorithm for dynamic braking, i.e. during vehicle rolling, by the electromechanical parking brake control unit,

[0033] is a graph representing, as a function of time, the braking command, the electric current flowing in the electromechanical unit, the braking force and the state of the actuator, in a state-of-the-art braking system used by following the algorithm of the,

[0034] is a graph gathering different measurements of electrical voltage, electrical current, deceleration, control signal, state, speed, slip coefficient carried out during the use of the braking system of the,

[0035] is a logic diagram illustrating the exchanges of information between the vehicle's electronic stability control (ESC) computer and the brake control device, during an implementation of the method according to the described embodiment of the invention,

[0036] illustrates the application of braking force and its regulation according to the driver's pressure on the brake pedal and wheel slippage,

[0037] and are two graphs bringing together different measurements of electrical voltage, electrical current, deceleration, control signal, state, speed, slip coefficient carried out during use of the braking system by implementing the method according to the described embodiment of the invention,

[0038] is a graph showing the decelerations obtained in the event of failure of the hydraulic brake using the method according to the described embodiment of the invention, alone and combined with regenerative braking, compared to the deceleration obtained without the invention. Detailed description

[0039] A logic diagram shows the data exchanges occurring between the vehicle's electronic stability control (ESC) computer 30 and the control device 40 of the parking brake 41, in a particular embodiment of the method of the invention. In this example, the parking brake 41 is a disc brake.

[0040] The physical input quantities are:23: pedal travel sensor (PTS)24: pressure in the master cylinder (pMC)

[0041] The electronic stability control computer of the vehicle 30 contains a controller trigger 31 which takes into account the position of the brake pedal (not shown) and its crossing of a predetermined threshold position, beyond which a brake application must be applied, as indicated by the instruction 25 sent by the trigger 31 to the control device 40, to determine a clamping force which is supplied to the control device 40 as a setpoint value. This value is determined on the basis of the driver's request, represented by the arrow 26, itself translated by his manner of pressing the pedal (not shown). A logic, deterministic or possibly based on artificial intelligence, is implemented by computer means (not shown) to determine this clamping force setpoint to be supplied to the control device 40.The pedal position is one of the input parameters of this logic, provided by the pedal travel sensor 23.

[0042] At the same time, the vehicle's electronic stability control computer 30 transmits information 27 to the control device 40 about a malfunction of the hydraulic braking unit. This information results in a command to switch the parking brake to dynamic mode.

[0043] Switching to dynamic mode

[0044] When a malfunction of the hydraulic braking unit occurs, the control device 40 is informed by the electronic stability control computer of the vehicle 30 and places itself in dynamic mode 42 so as to prepare the electromechanical unit to provide assistance with braking in the event of a request from the driver.

[0045] Three situations are then possible.

[0046] 1 èresituation: the brakes are released.

[0047] The control device 40 begins the recalibration of the electromechanical unit by applying a temporary current increase to the electric motor of said electromechanical unit. The current increase is, in the example, 1 A. A value between 0.5 A and 1.5 A is preferred.

[0048] Immediately after this increase in intensity, a release is applied by returning to the initial intensity for a release time which, in the example, is 50 ms. A duration of 100 ms is another possible example. A residual brake application torque is thus limited.

[0049] 2 ème situation: the parking brakes are activated.

[0050] The control device 40 temporarily releases the parking brakes. The duration of the release is, in the example, 50 ms. A residual brake application torque is thus limited.

[0051] 3ème situation: the brakes are already being used as emergency brakes because the process has already started in a previous cycle.

[0052] A release is applied for a release time which, in the example, is 50 ms. A residual brake application torque is thus limited.

[0053] Once the electromechanical unit is in dynamic mode, it is ready to respond to a braking request from the driver.

[0054] Driver request

[0055] When the vehicle's electronic stability control computer 30 transmits a braking request from the driver, in the form of a clamping force setpoint determined as a function of the way in which the driver has pressed said pedal, the control device 40 modifies the electrical power supply to the motor of the electromechanical unit to increase the clamping force of the parking brake. The increase in the clamping force is first achieved by applying a predetermined increase in electrical current to the motor (1 A in the example described). Then the clamping force is increased by brief successive applications of current each having a predetermined duration (50 ms in the example described). These brief successive applications ensure good progressiveness and make it possible to achieve the targeted deceleration.At least N applications of the predetermined duration are required to ensure that the target deceleration level is achieved while maintaining good vehicle stability. In the example described, N is 9. N can range from 6 to 12 if the vehicle is moving and from 3 to 7 if the vehicle is stationary.

[0056] The right and left rear wheel brakes are independently controlled for driver convenience.

[0057] If slippage is detected, a release can be applied for a release time of between 50 ms and 90 ms to ensure good responsiveness and avoid instability on slippery roads with low grip coefficient (mue).

[0058] The clamping force is adjusted by brief applications or brief releases, depending on the driver's demand.

[0059] More specifically, with reference to the, we will describe in detail each of the state changes of the algorithm. Each rear wheel, left and right, follows its own algorithm sequence, independently of the other.

[0060] From the entry point 43 of the dynamic mode, the control device 40 begins with a test 44 which makes it possible to check the slip state of the wheel. If the slip coefficient is lower than a predetermined threshold for triggering a new cycle, this means that the slip is sufficiently low to start a tightening cycle. We enter the “application” state, sub-state “1 ère application » 45.

[0061] When the cycle begins, the on-board computer 30 provides the clamping force setpoint. The clamping force is increased by incrementing the electrical intensity of the current supplying the motor of the electromechanical unit by 1 A.

[0062] From this state 45, a test 46 is used to check whether the electric current at the motor terminals is greater than a threshold value, which is defined as the value corresponding to the tightening setpoint. If this is already reached, we move to the "stop" state 47. Similarly, test 48 determines whether the slip becomes too significant because it is greater than a tightening end threshold. Then, we move to the same "stop" state 47.

[0063] Otherwise, after expiration 49 of a predetermined duration, we move to the “stop” state 47.

[0064] From the "stop" state 47, a test 50 is used to check that the current in the motor has not yet reached the value corresponding to the brake application setpoint and that the slip remains below the end of application threshold. If this is the case, we return to the "application" state, but in the "brief application" sub-state 51.

[0065] A test 52 determines whether the slippage is greater than a release threshold. We then move to a “release” state 53.

[0066] Another test 54 determines whether the current in the motor is lower than the value corresponding to the brake application setpoint. We then also move to the “release” state 53.

[0067] From the “brief application” sub-state 51, after expiration 49 of a predetermined duration, we check by test 48 that the sliding is still suitable, then we return to the “stop” state 47, etc.

[0068] From state “1 ère application » 45, a test 55 determines when the duration of the brief applications has expired or the intensity corresponding to the tightening setpoint has been reached, we move to the “release” state 53 and the tightening force setpoint is reset to zero.

[0069] From the “release” state 53, after expiration 56 of a predetermined duration, we return to the “stop” state 47, unless a test 57 determines that a braking request is expressed in the form of a new instruction (which may be the same as previously because the need for braking persists) and that the slip becomes lower than the release threshold. Then, we return to the entry point 43.

[0070] A test 58 determines whether no braking request is expressed. Then, we move to a "waiting" state 59, a state that we will leave if a test 60 confirms that a non-zero braking instruction is again expressed, independently of the slip, to reach the entry point 43.

[0071] In this algorithm, the main parameters are: - slip coefficient for stop, - slip coefficient for release, - slip coefficient for new cycle, - target current for first application, - duration of short application.

[0072] The main input data are:- front and rear, right and left wheel speeds,- target braking force provided by the vehicle's electronic stability control computer.

[0073] The main states are: - "application", with two sub-states "first application" and "brief application", - "stop", - "release", - "entry point".

[0074] Thresholds can be adjusted depending on vehicle speed.

[0075] In particular, we can distinguish depending on whether the vehicle is moving at more than 10 km / h or less than 5 km / h, it being understood that the thresholds of 5 km / h and 10 km / h are parameters that can be adjusted depending on the vehicle and the specifications.

[0076] The following Table 1 shows the nominal values ​​to be used for a vehicle moving at more than 10 km / h.

[0077] clamping target (%)2030405060708090100target current (A)22.533.544.555.56N123456789TargetIdle + 1A + 50ms50ms50ms50ms50ms50ms50ms50ms50ms

[0078] Table 2 below shows the values ​​to use for a vehicle moving at less than 5 km / h.

[0079] clamping target (%)2030405060708090100target current (A)1111.522.533.54N123456789TargetIdle + 0.7AIso step 1Iso step 150ms50ms50ms50ms50ms50msOther parameters:- Short application time: 50 ms- Release time: no-load current (also called "idle") + 50 ms

[0080] Figures 6 and 7 show the different signals and physical quantities reflecting the evolution of the wheels and the electromechanical unit during braking.

[0081] In detail, these signals and quantities are: - parking brake command 10, - deceleration 9 in m / s 2,- state 15 of the left actuator,- state 16 of the right actuator,- the requested force (%) 61,- the master cylinder pressure (bar) 24,- the speed 17 of the left front wheel,- the speed 18 of the right front wheel,- the speed 19 of the left rear wheel,- the speed 20 of the right rear wheel,- the slip coefficient 22 of the left rear wheel,- the command 13 for applying the left parking brake,- the state 66 of the power stage of the left parking brake,- the electric current 11 applied to the left electric motor,- the left application setpoint 62,- the left application value 63 reached,- the slip coefficient 21 of the right rear wheel,- the command 14 for applying the right parking brake,- the state 67 of the power stage of the right parking brake,- the electric current 12 applied to the electric motor right,- the right tightening instruction 64,- the right tightening value 65 reached.

[0082] As seen in the figure, longitudinal acceleration is progressive and directly linked to the driver's wishes.

[0083] Actuators are managed independently by short applications. Short applications are suspended if a slip is detected.

[0084] As seen in the, the actuators are managed independently in case of slip detection. A short release duration is adjusted according to the duration of the slip.

[0085] On the, the deceleration obtained in three circumstances of faulty hydraulic braking is shown: - by the embodiment described: curve 68, - by the embodiment described, combined with regenerative braking, because the vehicle is hybrid or electric: curve 69, - braking with support of the non-controlled parking brake according to the invention: curve 70.

[0086] The example described above concerns a disc parking brake.

[0087] The invention also applies to the case of a drum brake. The parameters should then be adapted as follows.

[0088] The clamping force is increased by starting with a first increment, for example 1 A, as for a disc brake.

[0089] A release is applied by applying a protective current so as to avoid a backstop detection.

[0090] Brief applications under the same clamping force are iterated, to the maximum number of N, where N is between 6 and 12 in dynamic mode and between 3 and 7 in static mode. The duration of the brief applications is fixed between 30 ms and 80 ms.

[0091] For a drum brake, the recalibration phase is adapted to ensure an appropriate clamping force.

[0092] Since the behavior of a drum brake is less linear than that of a disc brake, the clamping force profile is different, as are the clamping parameters for applying the method according to the invention. In particular, it is necessary to increase the safety margins to avoid excessively high force at the rear stop.

[0093] Table 3 concerns a vehicle equipped with a drum parking brake traveling at more than 10 km / h.

[0094] clamping target (%)2030405060708090100target current (A)22.533.544.555.56N123456789TargetIdle +1A + 50ms50ms50ms50ms50ms50ms50ms50ms50ms

[0095] Table 4 relates to a vehicle equipped with a drum parking brake travelling at less than 5 km / h and having a target application force of less than 5%.

[0096] clamping target (%)2030405060708090100target current (A)1111.522.533.54N123456789TargetIdle + 0.7AIso step 1Iso step 150ms50ms50ms50ms50ms50msOther parameters:- Short application time: 50 ms- Release time: no-load current (also called "idle") + 70 ms

[0097] A release is applied, just like a disc brake, but increased compared to a disc brake.

[0098] The invention is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art.

[0099] Reference list1 . . . initial operating state3 . . . release state4 . . . hold state5 . . . electric current6 . . . control signal7 . . . clamping force9 . . . deceleration10 . . . brake command11 . . . electric current applied to the left electric motor12 . . . electric current applied to the right electric motor13 . . . right parking brake application command14 . . . left parking brake application command17 . . . left front wheel speed18 . . . right front wheel speed19 . . . left rear wheel speed20 . . . right rear wheel speed21 . . . right rear wheel slip coefficient22 . . . left rear wheel slip coefficient23 . . . PTS25 . . . brake application26 . . . driver request30 . . . vehicle electronic stability control (ESC) computer31 . . . controller trigger40 . . . control device41 . . .parking brake42 . . . dynamic mode43 . . . entry point44 . . . wheel slip status check45 . . . status “1. èreapplication »46 . . . check whether the electric current at the motor terminals is greater than a threshold value47 . . . “stop” state48 . . . check whether the slip becomes too great49 . . . predetermined duration50 . . . check of the current in the motor and of the slip51 . . . “brief application” state52 . . . check whether the slip is greater than a release threshold53 . . . “release” state54 . . . check whether the current in the motor is less than the value corresponding to the brake application instruction55 . . . check of the duration of the brief applications and of the intensity56 . . . predetermined duration57 . . . check whether a braking request is expressed58 . . . check whether no braking request is expressed59 . . . “wait” state60 . . . verification of a non-zero braking instruction61 . . . required force62 . . . left clamping instruction63 . . . left clamping value reached64 . . .right clamping setpoint65 . . . right clamping value reached66 . . . status of the power stage of the left parking brake67 . . . status of the power stage of the right parking brake,68 . . . deceleration obtained with the embodiment described69 . . . deceleration obtained with the embodiment described, combined with regenerative braking70 . . . deceleration obtained with support of a non-controlled parking brake according to the invention.

Claims

Dynamic braking method applicable to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, the method consisting of braking a rear wheel of the vehicle if the driver presses said pedal and in the event of a failure of the hydraulic braking system, characterized in that it consists of first placing the electromechanical unit in a dynamic state by consuming the functional clearances of the parking brake, in anticipation of a braking need expressed by the driver on the brake pedal, then applying a clamping force to the parking brake in its dynamic state when a braking need is expressed by the driver and in that the braking of the rear wheel is carried out depending on the way in which the driver pressed said pedal. Method according to claim 1, in which the dynamic setting consists of:- if the parking brake is released: recalibrating the electromechanical unit by applying a temporary increase in current to its electric motor, then releasing the parking brake by returning to the initial current for a release period,- if the parking brake is activated, releasing the parking brake for a release period,- if the parking brake is already requested as an emergency brake because the process has already started during a previous cycle, releasing for a release period. Method according to claim 1, in which the application of the clamping force consists of:- recovering a braking request from the driver in the form of a clamping force setpoint determined as a function of the way in which the driver has pressed said pedal,- modifying the electrical supply to the motor of the electromechanical unit to increase the clamping force of the parking brake, first carried out by applying a predetermined increase in electrical current to the motor, then by increasing the clamping force by brief successive applications of current each having a predetermined duration. A method according to any preceding claim, wherein the predetermined additional electrical current to the motor is 1 A. A method according to any preceding claim, wherein the predetermined duration of the short applications is 50 ms. Method according to any one of the preceding claims, in which the number of successive current applications is limited to a value between 6 and 12, preferably 9, for the dynamic mode and between 3 and 7 for the static mode. Motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, characterized in that it comprises a brake pedal travel sensor, an electronic stability control computer and means for implementing the method according to any one of claims 1 to 6.

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