Method and system for controlling wheel slip in a braking system employing BBW technology in a vehicle.

Abstract

A method (500) for controlling wheel slip in a vehicle braking system includes: receiving (501) information representing a vehicle and information representing an estimated vehicle state by an input interface module of a slip control module; outputting input wheel slip control information by the input interface module (502); determining (503) wheel slip control parameters by a parameter self-loading module of the input interface module based on the information representing the vehicle and the information representing the vehicle state; determining (505) a plurality of wheel slip control activation signals by a plurality of wheel slip control activation modules of the slip control module based on the received input wheel slip control information and the received wheel slip control parameters; and determining (506) a setpoint value of a control variable to be applied to a corresponding vehicle corner by each of a plurality of closed-loop wheel slip control modules of the slip control module based on a defined slip setpoint and an estimated wheel slip value, so as to minimize the error between the defined slip setpoint and the estimated wheel slip.

Description

TECHNICAL FIELD

[0001] The present invention relates to a braking system of a vehicle, in particular, the present invention relates to a method for controlling the wheel slip in a braking system of a vehicle employing B-b-W technology and a system thereof. BACKGROUND

[0002] Wheel slip control is very important in vehicles and is added to the configuration of the braking system, inasmuch as the braking system must be able to guarantee a high level of control optimization and flexibility.

[0003] In traditional braking systems, characterized by the fact that the actuation circuit is provided with a number of valves, the braking management is generally performed through a discrete cyclic control algorithm (cyclic application-release of the braking request), there is an architecture that does not allow the separation between, for example, the control of the wheel slip of the vehicle and the control of the continuous force modulation to the actuators suitable for applying the braking to the wheels, whereby, in practice, the optimization and flexibility of any kind of the overall method for controlling the braking system to achieve the best performance in terms of wheel control are limited, and at the same time the modulation technique is limited to an empirical approach.

[0004] The most recent innovative architectures propose a braking system provided with an electronic braking system employing B-b-W ("Brake-by-Wire", braking by electrical connection) technology, in which, for example, the braking action of the brake calipers on the wheels is achieved through the use of one or more electromechanical actuators or electro-hydraulic actuators.

[0005] However, based on the above considerations with respect to the traditional braking systems, the method for controlling the wheel slip of the vehicle that can be used in the traditional braking systems is not optimal for the application in a braking system provided with an electronic braking system employing B-b-W technology.

[0006] Today, therefore, there is a felt need to define a specific and optimized mode for controlling the wheel slip of the vehicle for a braking system provided with an electronic braking system employing B-b-W technology, and this control mode can be configured as a function of the evaluation of the state of one or more wheels and / or of the vehicle itself. SUMMARY

[0007] TECHNICAL SOLUTION

[0008] It is an object of the present application to devise and provide a method for controlling wheel slip in a braking system of a vehicle which can at least partially avoid the above mentioned drawbacks with respect to the prior art and in particular allows, for example, to configure such control mode as a function of the evaluation of the state of one or more wheels and / or of the vehicle itself, thus ensuring greater flexibility and further personalizing and optimizing the responsiveness and performance of the wheel slip control and the braking comfort.

[0009] This object is achieved by the method according to claim 1.

[0010] The present application also relates to a system for controlling wheel slip in a braking system of a vehicle.

[0011] Other advantageous embodiments are the object of the dependent claims. BRIEF DESCRIPTION OF DRAWINGS

[0012] Further features and advantages of the method and system according to the present application will become apparent from the following description of preferred embodiments, given by way of indicative and non-limiting example, with reference to the attached drawings, wherein:

[0013] - Figure 1 A vehicle and an electronic braking system employing the technology of brake-by-wire, in which the system for controlling wheel slip in a braking system of a vehicle object of the present application can be employed, is shown in block diagram;

[0014] - Figure 2 Details of the vehicle and of the electronic braking system employing the technology of brake-by-wire in Figure 1 , as well as of the various components within the vehicle and the electronic braking system, are shown in block diagram;

[0015] - Figure 3a , Figure 3b and Figure 3c The system for controlling wheel slip of a vehicle according to various embodiments of the present application is shown in respective block diagrams;

[0016] - Figures 4a to 4g The various components of the system for controlling wheel slip in a braking system of a vehicle according to the present application are shown schematically;

[0017] - Figure 5 The method for controlling wheel slip in a braking system of a vehicle according to an embodiment of the present application is shown in block diagram; and

[0018] - Figure 6 An example of the operation of the components of the system for controlling wheel slip in a braking system of a vehicle is shown in block diagram. DETAILED DESCRIPTION

[0019] With reference now to the attached drawings, the reference numeral 100 generally indicates a system for controlling wheel slip in a braking system of a vehicle, according to the present application, hereinafter also simply system.

[0020] It should be noted that identical or similar elements in the figures will be identified by the same numerals or alphanumeric designations.

[0021] For the purposes of the present description, the "vehicle" schematically shown in the attached drawings is any vehicle or motorcycle having two, three, four or more wheels and also belonging to the commercial type.

[0022] Furthermore, the "braking system" means the whole of all the components (mechanical and / or electric or electronic, as well as the braking fluid) that contribute to generating the service braking of the vehicle or to generating the parking braking of the vehicle.

[0023] The system 100 is an electronic system that employs the technology of brake-by-wire.

[0024] The system 100 is operatively associated with the vehicle 1.

[0025] More in detail, the system 100 comprises a slip control module 101.

[0026] Wheel slip means the behavior of a wheel due to the relative difference between the wheel speed and the vehicle speed.

[0027] The slip control module 101 is, for example, a hardware module or a software logic module in the main hardware module of the braking system or, more generally, of the vehicle.

[0028] The system 100 also comprises a plurality of actuator modules 102.

[0029] Each module of the plurality of actuator modules 102 comprises a respective actuator control module and a respective actuator adapted to execute a braking command based on the control received from the corresponding actuator control module.

[0030] Each actuator control module is, for example, a hardware module or a software logic module in the main hardware module of the braking system or, more generally, of the vehicle 1.

[0031] Each actuator is of the electromechanical type or of the electro-hydraulic type.

[0032] The slip control module 101 is configured to receive information MD representative of the vehicle 1 and, based on this information MD, to send one or more commands representative of a braking request BR to the plurality of actuator modules 102.

[0033] For the purposes of the present description, the information MD representative of the vehicle is intended to mean information detected and / or estimated from detection devices (real or virtual sensors) installed on the vehicle, i.e. at the corner portions (front or rear of the vehicle), but not necessarily only related to the braking system of the vehicle.

[0034] The plurality of actuator modules 102 is configured to exert one or more braking actions BA on the corner portions 110 of the vehicle 1, based on the one or more commands representative of the braking request BR received from the slip control module 101.

[0035] It should be noted that a “braking action” is intended to mean a braking force / torque that can be exerted by an actuator module on the corresponding wheel.

[0036] It should be noted that the slip control module 101 is configured to provide, in addition to the one or more braking request BR commands to the plurality of actuator modules 102, a control mode MC and configuration parameters CP, which will be described in more detail below.

[0037] With reference to Figure 2 , the wheel slip control module 101 comprises a plurality of wheel slip control sub-modules 103.

[0038] The wheel slip control sub-modules of this plurality of wheel slip control sub-modules 103 are configured to control the corresponding corner portions of the vehicle 1.

[0039] In more detail, if the vehicle 1 has four wheels (two wheels on the front axle and two wheels on the rear axle), the plurality of wheel slip control sub-modules 103 comprises:

[0040] - a first wheel slip control sub-module C-FL of the left front corner portion;

[0041] - a second wheel slip control sub-module C-FR of the right front corner portion;

[0042] - a third wheel slip control sub-module C-RL of the left rear corner portion;

[0043] - a fourth wheel slip control sub-module C-RR of the right rear corner portion.

[0044] With reference again to Figure 2 , the plurality of actuator control modules 102 is distributed on the corner portions of the vehicle 1.

[0045] In more detail, if the vehicle 1 has four wheels (two wheels on the front axle and two wheels on the rear axle), the plurality of actuator control modules 102 comprises:

[0046] - a first actuator control module A-FL of the left front corner portion;

[0047] - a second actuator control module A-FR of the right front corner portion;

[0048] - a third actuator control module A-RL of the left rear corner portion;

[0049] - a fourth actuator control module A-RR of the right rear corner portion.

[0050] The one or more commands representative of a braking request BR sent from the slip control module 101 to the plurality of actuator control modules 102 include:

[0051] - a first braking request BR1 provided by the first wheel slip control submodule C-FL of the left front corner portion to the first actuator control module A-FL of the left front corner portion;

[0052] - a second braking request BR2 provided by the second wheel slip control submodule C-FR of the right front corner portion to the second actuator control module A-FR of the right front corner portion;

[0053] - a third braking request BR3 provided by the third wheel slip control submodule C-RL of the left rear corner portion to the third actuator control module A-RL of the left rear corner portion;

[0054] - a fourth braking request BR4 provided by the fourth wheel slip control submodule C-RR of the right rear corner portion to the fourth actuator control module A-RR of the right rear corner portion.

[0055] It should be noted that each wheel slip module is configured to provide, in addition to the respective braking request BR1, BR2, BR3 or BR4 to the plurality of actuator modules 102, a control mode MC-1, MC-2, MC-3 or MC-4 and configuration parameters CP-1, CP-2, CP3 or CP-4, which will be described in more detail below.

[0056] The one or more braking actions BA that the plurality of actuator modules 102 can implement on the vehicle 1 include:

[0057] - a first braking action BA1 provided by the first actuator control module A-FL of the left front corner portion to the left front wheel W-FL of the vehicle 1;

[0058] - a second braking action BA2 provided by the second actuator control module A-FR of the right front corner portion to the right front wheel W-FR of the vehicle 1;

[0059] - a third braking action BA3 provided by the third actuator control module A-RL of the left rear corner to the left rear wheel W-RL of the vehicle 1;

[0060] - a fourth braking action BA4 provided by the fourth actuator control module A-RR of the right rear corner to the right rear wheel W-RR of the vehicle 1.

[0061] It should be noted that, in Figure 2 , the vehicle 1 further comprises a chassis CS to which a front axle comprising the front left wheel W-FL and the front right wheel W-FR and a rear axle comprising the rear left wheel W-RL and the rear right wheel W-RR are operatively connected.

[0062] Furthermore, as schematically shown in Figure 2 , the vehicle 1 comprises a braking request module 111 configured to issue a braking request to the vehicle 1.

[0063] The braking request that the braking request module 111 is able to deliver is one of the items of information MD provided to the control module 100 representative of the vehicle.

[0064] In an embodiment, as shown in Figure 2 , the braking request module 111 comprises a brake pedal BP adapted to allow a driver of the vehicle 1 to issue a braking request to the vehicle 1.

[0065] In this embodiment, the braking request is referred to as the position and / or pressure of the brake pedal.

[0066] According to an alternative to the previous embodiment or in combination with the previous embodiment and shown in dashed lines in Figure 2 , the braking request module 111 comprises one or more control logics BC configured to issue a braking request, such as, for example, an automatic vehicle driving assistance logic, for example of the automatic emergency braking (AEB) type, an automatic autonomous driving logic, etc.

[0067] According to various embodiments, as schematically shown in Figure 3a , Figure 3b and Figure 3c , the system 100 is able to be configured from a software point of view based on the distribution of one or more electronic control units in the vehicle 1.

[0068] The one or more electronic control units have a plurality of tasks, one of which is to implement the slip control module 101.

[0069] It should be noted that a single electronic control unit can be configured to implement N wheel slip control sub-modules.

[0070] In the case where the vehicle has N corners and a single electronic control unit configured to implement all N wheel slip control sub-modules, the system 100 is said to be centralized.

[0071] Conversely, in the case where the vehicle has N corners and N electronic control units, each of which is configured to implement a single wheel slip sub-module, the system 100 is said to be decentralized.

[0072] This modularity of the system 100 according to these embodiments allows the system 100 itself to have greater flexibility with respect to the various distribution configurations of one or more electronic control units in the vehicle 1.

[0073] According to an embodiment, as shown in Figure 3a The system 100, in particular the plurality of wheel slip control sub-modules 103 distributed on the various corners C-1, C-2,..., C-N of the vehicle 1, can be configured to control, in a coordinated manner, a number of corners of the vehicle less than or equal to the total number of corners of the vehicle 1.

[0074] In this configuration, also referred to as fully decentralized system (B-b-W decentralized-all), the distribution of the electronic control units and the distribution of the wheel slip control sub-modules is based on the corners of the vehicle 1.

[0075] In an embodiment, this configuration can provide for the presence of an electronic control unit for each corner and the presence of a wheel slip control sub-module for each control unit related to the associated corner.

[0076] For example, with reference to Figure 3a The corner C-1 can be the front left corner to which the first wheel slip control sub-module C-FL corresponds.

[0077] According to another embodiment adapted to provide greater flexibility, the electronic control units can be configured to implement a plurality of corner wheel slip control sub-modules, while the other electronic control units are not configured to implement any wheel slip control sub-module.

[0078] According to another embodiment, as shown in Figure 3b The system 100, in particular the plurality of wheel slip control sub-modules 103 distributed on the various axes A-1, A-2,..., A-N of the vehicle 1, can be configured to control, in a coordinated manner, a number of axes of the vehicle less than or equal to the total number of axes of the vehicle 1.

[0079] In this configuration, also referred to as partially distributed system (B-b-W distributed - partial), the distribution of the electronic control units and the distribution of the wheel slip control sub-modules are based on the axles of the vehicle 1.

[0080] In an embodiment, the configuration can provide for the presence of an electronic control unit for each axle and for each control unit of the wheel slip control sub-modules related to the corner associated with that axle.

[0081] For example, with reference to Figure 3b , the single axle A-1 can be the front axle and can comprise a first wheel slip control sub-module C-FL and a second wheel slip control sub-module C-FR.

[0082] According to a further embodiment adapted to provide greater flexibility, the electronic control unit can be configured to implement a plurality of wheel slip control sub-modules of an axle.

[0083] According to a further embodiment, as shown in Figure 3c , the system 100, in particular the slip control module 101 - in the case where the slip control module 101 is centralized - can be configured to control a number of corner sections of the vehicle 1 less than or equal to the total number of corner sections of the vehicle 1 in a coordinated manner.

[0084] In this configuration, also referred to as centralized system (B-b-W centralized), there is a single electronic control unit comprising a plurality of wheel slip control sub-modules 103 of the single corner sections C-1, C-2,..., C-N of the vehicle 1.

[0085] Reference will now be made to Figures 4a to 4g , the slip control module 101 will be described in greater detail.

[0086] It should be noted that, from a software point of view, the wheel slip control module 101 and therefore each wheel slip control sub-module of the plurality of wheel slip control modules 103 is configured to perform a method for controlling the wheel slip in the braking system of the vehicle, as will be described hereinafter.

[0087] The slip control module 101 comprises an input interface module 40.

[0088] For example, the input interface module 40 is a hardware module or a software logic module of the main hardware modules of the braking system or, more generally, of the vehicle 1.

[0089] The input interface module 40 is configured to receive the input information MD representative of the vehicle 1 and the information MS representative of the estimated state of the vehicle previously referred to Figure 1 and Figure 2 .

[0090] The information MD representative of the vehicle 1 is provided by components equipped by the vehicle 1, such as for example sensors and / or a CAN (Controller Area Network) network and / or one or more electronic control units of a single corner of the vehicle.

[0091] In this regard, as shown in Figure 4a The information MD representative of the vehicle comprises one or more of the following groups of information:

[0092] - a first group of information MD-1 detectable by sensors equipped by the vehicle 1;

[0093] - a second group of information MD-2 detectable by the CAN network or other data communication channel of the vehicle 1;

[0094] - a third group of information MD-3 detectable by one or more electronic control units of a single corner of the vehicle.

[0095] It should be noted that said third group of information MD-3 also comprises information detectable in vehicle corners other than the one involved by the slip control module 101.

[0096] On the contrary, the information MS representative of the estimated state of the vehicle is provided by an estimation module MSV of the state of the vehicle (shown only in Figure 6 ).

[0097] For example, the estimation module MSV of the state of the vehicle is a hardware module or a software logic module in the main hardware modules of the braking system or, more generally, of the vehicle 1.

[0098] In an embodiment, the module MSV can be internal to the system 100.

[0099] According to another embodiment, which replaces the previous one, the module MSV can be external to the system 100.

[0100] Returning to the input interface module 40, this is configured to output input wheel slip control information SCD, i.e. which will be provided as input to other modules of the slip control module 101 arranged downstream of the input interface module 40.

[0101] The input wheel slip control information SCD is necessary information for the control of the wheel slip by the wheel slip control module 101 and is selected by the interface module 40 from the information MD representative of the vehicle 1 and the information MS representative of the state of the vehicle.

[0102] In more detail, the input wheel slip control information SCD comprises at least:

[0103] - vehicle speed (provided by the estimation module of the vehicle state);

[0104] - longitudinal acceleration of the vehicle (detectable by sensors on board the vehicle);

[0105] - lateral acceleration of the vehicle (detectable by sensors on board the vehicle);

[0106] - yaw rate (detectable by sensors on board the vehicle);

[0107] - vehicle speed (provided by the estimation module of the vehicle state);

[0108] - wheel slip (provided by the estimation module of the vehicle state);

[0109] - grip (provided by the estimation module of the vehicle state);

[0110] - wheel acceleration (provided by the estimation module of the vehicle state);

[0111] - lateral slip angle (provided by the estimation module of the vehicle state);

[0112] - lateral wheel slip (provided by the estimation module of the vehicle state);

[0113] - identification of the type of vehicle handler (provided by the estimation module of the vehicle state);

[0114] - other vehicle corner state information (described below, slip control enabling SCE, SP-V setpoint values of the control variables to be applied to the corresponding vehicle corner).

[0115] With reference again to Figure 4a , the input interface module 40 comprises a parameter self-loading module 41.

[0116] For example, the parameter self-loading module 41 is a software module or a software logic module of the main hardware modules of the braking system or, more generally, of the vehicle 1.

[0117] The parameter self-loading module 41 is configured to determine, on the basis of the information MD representative of the vehicle 1 and the information MS representative of the state of the vehicle 1, the wheel slip control parameters SCP used by the control logic of the wheel slip control module 101.

[0118] The wheel slip control parameters SCP are parameters used in the formulas / laws for controlling the other modules of the wheel slip control module 101 arranged downstream of the input interface module 40 and described below with reference to Figures 4b to 4g .

[0119] Some examples of these parameters are the gain and time constant of the controller, the slip setpoint table, and the triggering threshold for the above-mentioned modules.

[0120] In the following sections, examples of determination are indicated in terms of loading of a set of parameters as a function of the grip.

[0121] The wheel slip control parameters SCP can be divided into discrete subsets or can be determined as an output of an interpolation function based on information MD representative of the vehicle 1 and information MS representative of the state of the vehicle 1.

[0122] According to an embodiment, the wheel slip control parameters SCP can be divided into various subsets with respect to various grips (“high grip”, “medium grip”, “low grip”) and as a function of the estimated grip received from the estimation module of the state of the vehicle 1, and the parameter self-loading module 41 is configured to load the corresponding subset of wheel slip control parameters SCP.

[0123] According to another embodiment, which is an alternative to the previous one, the parameter self-loading module 41 is configured to determine the wheel slip control parameters SCP as a function of the estimated grip received from the estimation module of the state of the vehicle 1, for example:

[0124] the parameter SCP = default parameter SCP x function (default grip / estimated grip), where:

[0125] - default parameter SCP: associated / calibrated parameter for the default grip (for example, a specific gain of the wheel slip control module)

[0126] - function = interpolation logic that adapts the parameter to the estimated grip (for example, using linear interpolation logic: parameter SCP = default parameter SCP x (default grip / estimated grip);

[0127] - default grip: high grip, dry asphalt, μ = 1.

[0128] With reference to Figure 4b , the wheel slip control module 101 also comprises a plurality of wheel slip control enabling modules 42.

[0129] For example, each of the plurality of wheel slip control enabling modules 42 is a software module or software logic within a main hardware module of the braking system or, more generally, of the vehicle 1.

[0130] The plurality of wheel slip control enabling modules 42 comprises at least one wheel slip control enabling module for each corner of the vehicle.

[0131] For example, with reference to Figure 4b, said plurality of wheel slip control enabling modules 42 comprises:

[0132] - a first enabling module E-FL for front left corner wheel slip control;

[0133] - a second enabling module E-FR for front right corner wheel slip control;

[0134] - a third enabling module E-RL for rear left corner wheel slip control;

[0135] - a fourth enabling module E-RR for rear right corner wheel slip control.

[0136] Said plurality of wheel slip control enabling modules 42 is configured to generate a plurality of wheel slip control enabling signals SCE based on the received input wheel slip control information SCD and the received wheel slip control parameters SCP.

[0137] In more detail, each wheel slip control enabling module of said plurality of wheel slip control enabling modules 42 is configured to determine a respective enabling signal of said plurality of wheel slip control enabling signals SCE based on the received input wheel slip control information SCD and the received wheel slip control parameters SCP.

[0138] It is noted that the wheel slip control enabling modules 42 are configured to enable wheel slip control upon detection of an imminent loss of wheel stability and / or vehicle stability.

[0139] For example, the wheel slip control enabling modules 42 are configured to detect an imminent loss of wheel stability and thus to enable (TRUE) wheel slip control of one or more corners of the vehicle by evaluating an estimate of the wheel slip estimate (WheelSlip) and comparing this estimate to a function of the vehicle state threshold (SlipThreshold[f(VehicleSpeed, Grip, BrakePedalSpeed, WheelAcceleration)]):

[0140] If WheelSlip >= SlipThreshold[f(VehicleSpeed, Grip, BrakePedalSpeed)], then SlipControlEnable (SCE) = TRUE.

[0141] According to a further embodiment, which is combined with the aforementioned embodiments and schematically shown in Figure 4c , the slip control module 101 further comprises a plurality of wheel slip setpoint limiting modules 43.

[0142] For example, each wheel slip setpoint limiting module of said plurality of wheel slip setpoint limiting modules 43 is a software module or software logic within a main hardware module of the braking system or, more generally, of the vehicle 1.

[0143] The plurality of wheel slip setpoint defining modules 43 comprises at least one wheel slip setpoint defining module for each corner of the vehicle.

[0144] With reference to Figure 4c The plurality of wheel slip setpoint defining modules 43 comprises:

[0145] - a first defining module D-FL of a first wheel slip setpoint for the front left corner;

[0146] - a second defining module D-FR of a second wheel slip setpoint for the front right corner;

[0147] - a third defining module D-RL of a third wheel slip setpoint for the rear left corner;

[0148] - a fourth defining module D-RR of a fourth wheel slip setpoint for the rear right corner.

[0149] The plurality of wheel slip setpoint defining modules 43 is configured to generate the wheel slip setpoint SP-S based on the received input wheel slip control information SCD and the received wheel slip control parameters SCP.

[0150] In an embodiment, the slip setpoint is a constant value, referred to as reference slip setpoint, defined by the parameter self-loading module 41 of the input interface module 40.

[0151] According to another embodiment, in combination with the previous one, the slip setpoint is determined by the respective defining module as a function of a respective reference slip setpoint, as information MS representative of the state of the vehicle.

[0152] The plurality of wheel slip setpoint defining modules 43 is configured to adjust the reference vehicle slip setpoint in real time, based on the received input wheel slip control information SCD and the received wheel slip control parameters SCP, for each single corner of the vehicle to obtain the optimal wheel slip setpoint, advantageously maximizing the dynamic performance during braking of the vehicle.

[0153] For example, the wheel slip setpoint (Slipsetpoint) can be modulated according to a reference wheel slip setpoint (SlipSetpoint reference) as a function of the grip and lateral acceleration of the vehicle:

[0154] Slipsetpoint = SlipSetpoint Reference * f (grip, lateral acceleration).

[0155] With reference to Figure 4d, the slip control module 101 further comprises a plurality of closed loop wheel slip control modules 44.

[0156] For example, each of the plurality of closed loop wheel slip control modules 44 is a software module or software logic within the main hardware module of the braking system or, more generally, of the vehicle 1.

[0157] The plurality of closed loop wheel slip control modules 44 comprises at least one closed loop wheel slip control module for each corner of the vehicle.

[0158] With reference to Figure 4d The plurality of closed loop wheel slip control modules 44 comprises:

[0159] - a first closed loop wheel slip control module CL-1 for the front left corner;

[0160] - a second closed loop wheel slip control module CL-2 for the front right corner;

[0161] - a third closed loop wheel slip control module CL-3 for the rear left corner;

[0162] - a fourth closed loop wheel slip control module CL-4 for the rear right corner.

[0163] Each closed loop wheel slip control module, including software adjustment logic (e.g. PID type control, acronym for Proportional-Integral-Derivative), is configured to determine, at each execution cycle of the respective software, a setpoint value SP-V of a control variable to be applied to the respective vehicle corner, based on a defined slip setpoint SP-S and an estimated wheel slip value, so as to minimize the error between the defined slip setpoint SP-S and the estimated wheel slip.

[0164] An example of a control variable is a force or a position or a voltage or a pressure or a torque or a current that can be implemented by means of a respective actuator on the vehicle corner.

[0165] In an embodiment combined with the previous one, each closed loop wheel slip control module comprises software logic for initializing or resetting the control logic based on discrete events (control activation and / or exceeding error threshold and / or event-driven logic for reducing or increasing the force required), to advantageously control the variable more quickly when faced with rapid changes in operating conditions.

[0166] According to another embodiment combined with the previous ones and schematically illustrated in Figure 4e The slip control module 101 further comprises a plurality of reference target correction modules 45.

[0167] The "reference target" is the setpoint value SP-V of the control variable applied to the corresponding vehicle corner determined by the closed loop wheel slip control module, as described above.

[0168] For example, each of the plurality of reference target correction modules 45 is a software module or software logic within the main hardware module of the braking system or, more generally, of the vehicle 1.

[0169] The plurality of reference target correction modules 45 comprises at least one reference target correction module for each corner of the vehicle.

[0170] With reference to Figure 4e The plurality of target correction modules 45 comprises:

[0171] - a first reference target correction module CT-1 for the front left corner;

[0172] - a second reference target correction module CT-2 for the front right corner;

[0173] - a third reference target correction module CT-3 for the rear left corner;

[0174] - a fourth reference target correction module CT-4 for the rear right corner.

[0175] The plurality of reference target correction modules 45 is configured to correct (overwrite and / or reduce) the reference target value received as input by providing as output a corrected reference target value TC, based on a discrete event (exceeding a slip threshold and / or exceeding a wheel acceleration threshold and / or open loop control request of a single corner).

[0176] It should be noted that the plurality of reference target correction modules 45 is configured to correct the reference target value by implementing a non-linear variation.

[0177] The non-linear variation of the control variable makes it possible to increase the responsiveness of the control in the event of a rapid variation of the controlled variable, for example by reducing the force value in the presence of high wheel acceleration (WheelAcc):

[0178] If WheelAcc >= WheelAccThreshold [f (vehicle speed, grip,...)], then ForceTarget = ForceTarget - ForceCompensation), where:

[0179] - WheelAcc = wheel acceleration (from input wheel slip control information SCD);

[0180] - WheelAccThreshold = acceleration threshold at which compensation is performed;

[0181] - ForceTargetOut = force TC (corrected reference target value) output from the plurality of reference target correction modules 45;

[0182] - ForceTargetIn = force SP_V (setpoint value) input to the plurality of reference target correction modules 45;

[0183] - ForceCompensation = force compensation value (included in the wheel slip control parameters SCP).

[0184] Reference will now also be made to the following Figure 4f The slip control module 101 also comprises a plurality of coordination modules 46 of the force FC defined for each corner of the vehicle.

[0185] For example, each force coordination module of the plurality of coordination modules defined for each corner of the vehicle is a software module or software logic within the main hardware modules of the braking system or, more generally, of the vehicle 1.

[0186] The plurality of coordination modules 46 comprises at least one force coordination module defined for each corner of a single axle of the vehicle.

[0187] Reference will now also be made to the following Figure 4f The plurality of force coordination modules 46 of the force defined for each corner of the vehicle comprises:

[0188] - a first coordination module FA-S of the force defined for the corners of the front axle, in particular adapted to provide a first slip control force FC-1 of the left front corner of the vehicle and a second slip control force FC-2 of the right front corner of the vehicle;

[0189] - a second coordination module RA-S of the force defined for the corners of the rear axle, in particular adapted to provide a third slip control force FC-3 of the left rear corner of the vehicle and a fourth slip control force FC-4 of the right rear corner of the vehicle.

[0190] The plurality of coordination modules 46 is configured to define, on the basis of the reference target values TC (setpoint values) of the control variables provided by the preceding modules, a saturation of the maximum force and / or minimum force that can be required for each single corner of the axle, by evaluating the conditions of grip, vertical load, stability and speed of the vehicle.

[0191] This limitation allows and optimizes the coordination of the logic defined for each corner / side of the vehicle to guarantee the overall stability of the vehicle.

[0192] For example, in case of different grip on the two sides of the vehicle, the high grip side can be limited according to the grip and the vehicle speed with the following logic:

[0193] Force saturation on high grip side = Force required by low grip side + Force value defined by a mathematical function receiving as input the vehicle information.

[0194] According to another embodiment, as Figure 4g illustratively shown in

[0195] For example, each configuration interface module of the plurality of configuration interface modules 47 is a software module or software logic within the main hardware modules of the braking system or more generally of the vehicle 1.

[0196] The plurality of configuration interface modules 47 comprises at least one configuration interface module for the actuator control module of each corner of the vehicle.

[0197] For example, with reference to Figure 4g , the plurality of configuration interface modules 47 comprises:

[0198] - a first configuration interface module CNF-1 for the front left corner actuator control module;

[0199] - a second configuration interface module CNF-2 for the front right corner actuator control module;

[0200] - a third configuration interface module CNF-3 for the rear left corner actuator control module;

[0201] - a fourth configuration interface module CNF-4 for the rear right corner actuator control module.

[0202] Each configuration interface module of the plurality of configuration interface modules 47 is configured to define a control (logic) mode MC of the actuator control module of the respective vehicle corner.

[0203] Furthermore, each interface configuration module of the plurality of interface configuration modules 47 is configured to define a set of configuration parameters CP to be provided for loading to the actuator control module of the related corner of the vehicle.

[0204] As shown in Figure 4g :

[0205] - a first configuration interface module CNF-1 is configured to define a first control mode MC-1 and a first set of configuration parameters CP-1 for the left front corner actuator control module, the first set of configuration parameters CP-1 being provided for loading to the left front corner actuator control module;

[0206] - a second configuration interface module CNF-2 is configured to define a second control mode MC-2 and a second set of configuration parameters CP-2 for the right front corner actuator control module, the second set of configuration parameters CP-2 being provided for loading to the right front corner actuator control module;

[0207] - a third configuration interface module CNF-3 is configured to define a third control mode MC-3 and a third set of configuration parameters CP-3 for the left rear corner actuator control module, the third set of configuration parameters CP-3 being provided for loading to the left rear corner actuator control module;

[0208] - a fourth configuration interface module CNF-4 is configured to define a fourth control mode MC-4 and a fourth set of configuration parameters CP-4 for the right rear corner actuator control module, the fourth set of configuration parameters CP-4 being provided for loading to the right rear corner actuator control module.

[0209] In more detail, each configuration interface module of the plurality of configuration interface modules 47 is configured to define the most suitable configuration in terms of control (logic) mode MC and in terms of set of configuration parameters CP to be provided for loading for the actuator control module of the respective corner of the vehicle based on each of the following: the input wheel slip control information SCD received (such as single corner information); the wheel slip control parameters SCP, such as the respective wheel conditions (slip and / or high acceleration, tire / grip conditions); the information MS representative of the state of the vehicle (vehicle speed, type of maneuver, type of road, vehicle instability conditions); and the setpoint values SP-V of the control variables (for example, forces) to be applied to the respective vehicle corner (see Figure 4d ).

[0210] The control (logic) mode MC represents a different control mode that can be activated for controlling the actuator.

[0211] A particular control mode differs from another control mode in the type of control mode and / or control architecture (for example, position control or actuator force control).

[0212] The set of configuration parameters is used for the particular control mode MC that is activated.

[0213] For example, in the case of activation of the high-grip slip control mode MC, the configuration interface module is implemented as a control mode MC, for example a closed-loop force control mode, to maximize the modulation speed and uses as a set of configuration parameters CP the specific configuration parameters used to control the desired high grip.

[0214] With reference to the preceding figures and Figure 5 The method 500 for controlling the wheel slip in a vehicle braking system according to the present application will now be described with reference to the block diagram in A.

[0215] It should be noted that the components and information mentioned hereinafter by the description of the method have been previously described with reference to the system 100 and will therefore not be repeated for the sake of brevity.

[0216] The method 500 comprises a symbolic step ST of start.

[0217] The method 500 comprises a step of reception 501 of information MD representative of the vehicle 1 and information MS representative of the estimated state of the vehicle by the input interface module 40 of the slip control module 101.

[0218] The method 500 also comprises a step of output 502 of the input wheel slip control information SC D by the input interface module 40.

[0219] The method 500 also comprises a step of determination 503 of the wheel slip control parameters SCP by the parameter self-loading module 41 of the input interface module 40 on the basis of the information MD representative of the vehicle 1 and the information MS representative of the state of the vehicle 1.

[0220] According to an embodiment, the wheel slip control parameters SCP can be divided into various subsets related to different grip levels (“high grip”, “medium grip”, “low grip”) and as a function of the estimated grip received from the state estimation module of the vehicle 1.

[0221] In this embodiment, the determination step 503 comprises a step of loading 504 of the respective subset of wheel slip control parameters SCP by the parameter self-loading module 41 of the input interface module 40.

[0222] According to another embodiment, which is an alternative to the previous one, the determination step 503 is performed by the parameter self-loading module 41 of the input interface module 40 for determining the wheel slip control parameters SCP as a function of the estimated grip received from the state estimation module MSV of the vehicle 1.

[0223] Turning in general to Figure 5The method 500 further comprises the following determination step 505, by the plurality of wheel slip control enabling modules 42 of the slip control module 101, of a plurality of wheel slip control enabling signals SCE based on the received input wheel slip control information SCD and the received wheel slip control parameters SCP.

[0224] The method 500 further comprises the following determination step 506, by each of the plurality of closed loop wheel slip control modules 44 of the slip control module 101, of a setpoint value SP-V of a control variable to be applied to the corresponding vehicle corner, based on the defined slip setpoint SP-S and the estimated wheel slip value, to minimize the error between the defined slip setpoint SP-S and the estimated wheel slip.

[0225] The method 500 comprises an ending symbolic step ED.

[0226] According to embodiments in combination with any one of the preceding embodiments, Figure 5 (dashed in the figure), the method 500 comprises, after the determination step 506, the following steps:

[0227] - a defining step 507, by each of the plurality of interface configuration modules 44 present in the actuator control module of each of the plurality of actuator modules 102, of a control (logical) mode MC of the actuator control module of the related corner of the vehicle 1;

[0228] - a defining step 508, by each of the plurality of interface configuration modules 44 present in the actuator control module of each of the plurality of actuator modules 102, of a set of configuration parameters CP to be provided for loading to the actuator control module of the related corner of the vehicle 1.

[0229] In embodiments in combination with any one of the preceding embodiments, Figure 5 (dashed in the figure), the method 500 comprises, between the determination step 505 and the determination step 506, the following generation step 509, by the plurality of slip setpoint defining modules 43 of the slip control module 101, of the slip setpoint SP-S based on the received input wheel slip control information SCD and the received wheel slip control parameters SCP.

[0230] In embodiments in combination with the preceding embodiment, Figure 5 (dashed in the figure), the generation step 509 comprises the following provision step 510, by the parameter self-loading module 41 of the input interface module 40, of a constant slip setpoint value as a reference slip setpoint value.

[0231] In another embodiment combined with the previous one (in dashed lines in Figure 5 the generation step 509 also comprises a determination step 511, by the respective limiting module, of the slip setpoint as a function of the respective reference slip setpoint indicative of the state of the vehicle 1.

[0232] According to another embodiment combined with one of the previous ones (in dashed lines in Figure 5 the method 500 also comprises, between the determination step 506 and the limiting step 507, a correction step 512, by a plurality of reference target correction modules 45 of each wheel slip control module, of the respective reference target value received at the input, based on a discrete event (exceeding a wheel slip threshold and / or exceeding a wheel acceleration threshold and / or requesting open-loop control of a single corner), then outputting the corrected reference target value TC.

[0233] According to another embodiment combined with the previous one (in dashed lines in Figure 5 the method 500 also comprises, between the limiting step 512 and the limiting step 507, a limiting step 513, by a plurality of coordination modules 46 of the forces FC defined for the corners of a single axle of the vehicle, of the saturation of the maximum force and / or minimum force that can be requested for a single corner of each axle, based on the setpoint values of the control variables, assessing the conditions of grip, vertical load, stability and speed of the vehicle.

[0234] With reference to Figure 6 An example of operation of the slip control module 101 will now be described.

[0235] The input interface module 40 is configured to receive in input the information MD indicative of the vehicle 1 previously referred to Figure 1 and Figure 2 introduced, as well as the information MS indicative of the estimated state of the vehicle provided by the estimation module MSV of the state of the vehicle.

[0236] The input interface module 40 outputs the input wheel slip control information SCD and determines the wheel slip control parameters SCP based on the information MD indicative of the vehicle 1 and the information MS indicative of the state of the vehicle 1, by the parameter self-loading module 41.

[0237] The first slip control enabling module E-FL generates the first wheel slip control enabling signal SCE of the front left corner based on the received wheel slip control parameters SCP and the input wheel slip control information SCD.

[0238] A first wheel slip setpoint defining module D-FL for the left front corner defines a first wheel slip setpoint SP-S based on the received wheel slip control parameters SCP and based on the received input wheel slip control information SCD.

[0239] A first closed loop wheel slip control module CL-1 for the left front corner determines, at each execution cycle of the corresponding software, a setpoint value SP-V of a control variable to be applied to the corresponding vehicle corner, based on the defined slip setpoint SP-S and on the estimated wheel slip value, so as to minimize the error between the defined slip setpoint SP-S and the estimated wheel slip, upon reception of a first enabling signal SCE.

[0240] A first reference target correction module CT-1 for the left front corner corrects (overwrites and / or reduces) the reference target value received as input by the first reference target correction module CT-1, based on discrete events (exceeding a slip threshold and / or exceeding a wheel acceleration threshold and / or open loop control request for a single corner), upon reception of a first enabling signal SCE, to provide a corrected reference target value TC as output.

[0241] A first coordination module FA-S of forces defined for the front axle corners provides a first slip control force Fl for the left front corner of the vehicle.

[0242] A first configuration interface module CNF-1 of the left front corner actuator control module defines a first control mode MC-1 of the left front corner actuator control module and a first set of configuration parameters CP-1 provided for loading to the first left front corner actuator control module A-FL which exerts a first braking action BA1 on the left front wheel W-FL of the vehicle 1.

[0243] It should be noted that the object of the present application has been fully achieved.

[0244] The method for controlling wheel slip in a vehicle braking system and the corresponding system of the present application are particularly for a brake-by-wire architecture and can configure the control mode of a single vehicle corner as a function of the state assessment of the wheel and / or of the vehicle determined by the control and monitoring algorithm.

[0245] The method and the corresponding control system can manage the wheel slip in a specific and optimized manner for a brake-by-wire system in which the control system of the vehicle braking logic, the logic relating to the control of the corners / wheels and the logic relating to the control of the actuators is defined in one or more control units and in which each corner is provided with a B-b-W actuator.

[0246] Furthermore, the method and the corresponding control system of the present application provide that the wheel slip control module configures the control mode of the single corner actuator control module as a function of the state of the wheel and / or of the vehicle, so as to select the best configuration and set of parameters, prioritizing and optimizing the control responsiveness and performance rather than the braking comfort.

[0247] Furthermore, the method and the corresponding control system of the present application have modularity / flexibility to make the vehicle class change as a function of the possibility of coordination between the corners of the vehicle.

[0248] Furthermore, the method and the corresponding system of the present application can constantly adjust the control logic based on the measurements and estimates of the vehicle distribution signals, by virtue of a more comprehensive architecture configuration and information / estimates / evaluations on the vehicle distribution.

[0249] Furthermore, the method and the corresponding control system of the present application guarantee:

[0250] - continuous modulation of the wheel slip control;

[0251] - correction of the control logic is simpler, since it is based on the physical laws that allow the use of theoretical corrections to support the empirical / experimental technique, rather than on typical empirical / experimental methods;

[0252] - adaptation of the control mode / actuator control parameters as a function of the control logic of the wheel slip control module of the respective vehicle corner.

[0253] Changes or modifications to the embodiments of the method and of the corresponding system described above can be made by the person skilled in the art, without departing from the scope of protection of the attached claims, or other elements functionally equivalent can be substituted to meet possible needs. All the features described above, which belong to one possible embodiment, can be implemented independently of the other described embodiments.

Claims

1. A method (500) for controlling wheel slip in a braking system of a vehicle (1), said method (500) being implementable by means of a relative control system (100) employing a brake-by-wire technology, said method (500) comprising the steps of: - receiving (501), by means of an input interface module (40) of a slip control module (101) of said system (100), information (MD) representative of said vehicle (1) and information (MS) representative of an estimated state of said vehicle (1); - outputting (502), by means of said input interface module (40), input wheel slip control information (SCD); - determining (503), by means of a parameter self-loading module (41) of said input interface module (40), wheel slip control parameters (SCP) based on said information (MD) representative of said vehicle (1) and said information (MS) representative of a state of said vehicle (1); - determining (505), by means of a plurality of wheel slip control enabling modules (42) of said slip control module (101), a plurality of enabling signals (SCE) of said wheel slip control based on said received input wheel slip control information (SCD) and said received wheel slip control parameters (SCP); - determining (506), by means of each closed loop wheel slip control module of a plurality of closed loop wheel slip control modules (44) of said slip control module (101), a setpoint value (SP-V) of a control variable to be applied to a corresponding vehicle corner in order to minimize an error between a defined slip setpoint (SP-S) and an estimated wheel slip, based on said defined slip setpoint (SP-S) and said estimated wheel slip value; - defining (507), by means of each interface configuration module (47) of a plurality of actuator control modules of an actuator module (102) of said system (100), a control mode (MC) of said actuator control module of a relative corner of said vehicle (1) based on said received input wheel slip control information (SCD), based on said wheel slip control parameters (SCP), based on said information (MS) representative of a state of said vehicle and based on said setpoint value (SP-V) of said control variable to be applied to a corresponding vehicle corner, said plurality of interface configuration modules (47) being comprised in said slip control module (101). ​ ​ ​ ​ ​ ​ - defining (508), by each interface configuration module (47) of the plurality of interface configuration modules of the actuator control module present in each actuator module of the plurality of actuator modules (102), a set of configuration parameters (CP) based on the input wheel slip control information (SCD) received, on the wheel slip control parameters (SCP), on the information representative of the state of the vehicle (MS) and on the setpoint value (SP-V) of the control variable to be applied to the corresponding vehicle corner, the set of configuration parameters (CP) being provided for loading to the actuator control module of the relative corner of the vehicle (1); - providing, by the slip control module (101), to the plurality of actuator modules (102) of the system (100), the respective control mode (MC) of the actuator control module of the relative corner of the vehicle (1) and the set of configuration parameters (CP) provided for loading to the actuator control module of the relative corner of the vehicle (1).

2. The method (500) according to claim 1, comprising the following generation (509) step, between the step of determining (505) the plurality of enable signals (SCE) of the wheel slip control and the step of determining (506) the setpoint value (SP-V) of the control variable to be applied to the corresponding vehicle corner to minimize the error between the slip setpoint (SP-S) defined and the estimated wheel slip: generating, by a plurality of wheel slip setpoint defining modules (43) of the slip control module (101), a slip setpoint (SP-S) based on the input wheel slip control information (SCD) received and on the wheel slip control parameters (SCP) received.

3. The method (500) of claim 2, wherein, The generation (509) step comprises the following provision (510) step: providing, by the parameter self-loading module (41) of the input interface module (40), a constant slip setpoint value as a reference slip setpoint.

4. The method (500) of claim 3, wherein, The generation (509) step also comprises the following determination (511) step: determining, by the respective defining module, a slip setpoint as a function of the respective reference slip setpoint as the information representative of the state of the vehicle (MS).

5. The method (500) according to any one of claims 1 to 4, further comprising, between the step of determining (506) the setpoint values (SP-V) of the control variables to be applied to the respective vehicle corner in order to minimize the error between the defined slip setpoint (SP-S) and the estimated wheel slip and the step of defining (507) the control mode (MC) of the actuator control module of the relative corner of the vehicle (1), the following correction (512) step: correction, by a plurality of reference target correction modules (45) of the slip control module (101), of the respective reference target values received at input on the basis of discrete events, then output of the corrected reference target values (TC).

6. The method (500) according to claim 5, further comprising, between the correction (512) step and the step of defining (507) the control mode (MC) of the actuator control module of the relative corner of the vehicle (1), the following definition (513) step: definition, by a plurality of modules (46) for coordinating the forces defined for the corners of a single axle of the vehicle (1), of the saturation of the maximum and / or minimum forces that can be requested for each single corner of each axle, on the basis of the setpoint values of the control variables, assessing the conditions of grip, vertical load, stability and speed of the vehicle (1).

7. The method (500) according to any one of claims 1 to 4, wherein The wheel slip control parameters (SCP) are divided into different subsets related to different grips according to the estimated grip received from the estimation module (MSV) of the state of the vehicle (1), the determining (503) step comprising the following loading (504) step: loading, by the parameter self-loading module (41) of the input interface module (40), of the respective subset of wheel slip control parameters (SCP).

8. The method (500) according to any of the preceding claims 1 to 4, wherein The step of determining (503) the wheel slip control parameters (SCP) is performed by the parameter self-loading module (41) of the input interface module (40) for determining the wheel slip control parameters (SCP) as a function of the estimated grip received from the estimation module of the state of the vehicle (1).

9. A system (100) for controlling the wheel slip in a braking system of a vehicle (1) employing a brake-by-wire technology, the system (100) comprising: - a slip control module (101); - a plurality of actuator modules (102), each of which comprises a respective actuator control module and a respective actuator adapted to implement a braking command on the basis of a control received from the respective actuator control module, the slip control module (101) being configured to receive information (MD) representative of the vehicle (1) and to send one or more commands representative of a braking request (BR) to the plurality of actuator modules (102) on the basis of the information (MD), The slip control module (101) is configured to perform the method for controlling wheel slip in a braking system of a vehicle (1) according to any one of claims 1 to 8.

10. The system (100) of claim 9, wherein, The slip control module (101) comprises a plurality of wheel slip control sub-modules (103) distributed over the corners (C-1, C-2,..., C-N) of the vehicle (1), the plurality of wheel slip control sub-modules (103) being configurable to control in a coordinated manner a number of corners of the vehicle less than or equal to the total number of corners of the vehicle (1).

11. The system (100) of claim 9, wherein, The slip control module (101) comprises a plurality of wheel slip control sub-modules (103) distributed over the axles (A-1, A-2,..., A-N) of the vehicle (1), the plurality of wheel slip control sub-modules (103) being configurable to control in a coordinated manner a number of axles less than or equal to the total number of axles of the vehicle (1).

12. The system (100) of claim 9, wherein, The slip control module (101) is centralized, the slip control module (101) being configurable to control in a coordinated manner a number of corners of the vehicle (1) less than or equal to the total number of corners of the vehicle (1). The slip control module (101) is centralized, the slip control module (101) being configurable to control in a coordinated manner a number of corners of the vehicle (1) less than or equal to the total number of corners of the vehicle (1).

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