Method and device for estimating the braking effort of a vehicle

Abstract

1. A method for estimating brake application of a vehicle, the vehicle comprising at least one braking element (3, 3') and at least one braked element (2) of at least one brake (1) of the vehicle, the braking element (3, 3') comprising at least one force sensor (6), and at least one electronic control unit (11) of the at least one brake (1) comprising the steps of: temporal acquisition by the control unit (11) of at least one force signal generated by the at least one force sensor (6); detection of significant temporal changes in the force signals; processing in the control unit (11) the significant changes in the force signals using a customized algorithm; reconstruction of time moments of brake application and release via the algorithm; and returning by the control unit (11) the time moments of brake application and release to an information system (19) and / or an on-board control application (20) and / or a dedicated algorithm (21) for estimating the performance and state of the braking system of the vehicle.

Description

[Technical Field]

[0001] The present invention relates to a device and method for estimating braking effort in a vehicle. Summary of the Invention

[0002] As is known, the evaluation, estimation, and recording of vehicle braking activity can be an important component in the evaluation, estimation, and recording of characteristic braking events that constitute more complex vehicle monitoring activities via known smart brake pad technology.

[0003] Conventional assessment involves detecting the position of the brake pedal under the action of the driver's foot, and from there, either directly or through various types of algorithms, tracking the required braking characteristics and the downstream characteristics of the braking system components, typically pressure fluctuations in the hydraulic lines, stress on the pedal, braking system responsiveness, braking effectiveness, speed fluctuations, etc.

[0004] In the context of increasingly complex control systems, the technical features that are usually associated with sophisticated systems for monitoring vehicles, and in particular their braking systems, are also of particular importance.

[0005] In this scenario, the control and monitoring of the braking system's efficiency and any characteristics that may limit its possible performance losses becomes increasingly important.

[0006] Advanced driver assistance systems (ADAS) are also known to autonomously assess and intervene during braking, typically in emergency situations where the control and enforcement of braking goes beyond the physical movement of the brake pedal.

[0007] Traditional assessment of braking effort through simple detection of brake pedal position can be slow, inaccurate, and inefficient compared to the information needs of more advanced systems known to detect and monitor braking characteristics.

[0008] The problem posed by the present invention is to overcome the above-mentioned limitations of the known technology.

[0009] Within this task, the object of the invention is to devise a method and a device that allows the estimation of the braking effort of a vehicle independently of the signal detected by the brake pedal.

[0010] The object of the invention is also to devise a method and a device that allows estimation of the braking effort of the vehicle at each brake pad.

[0011] A further object of the present invention is to devise a method and a device that allows real-time estimation of braking effort in a vehicle.

[0012] Finally, it is an object of the present invention to devise a device and a method for estimating braking effort in a vehicle by means compatible with on-board equipment and applications.

[0013] Finally, it is an object of the present invention to devise a device and a method for estimating braking effort in a vehicle by means compatible with on-board equipment and applications connected to remotely located recording and processing means.

[0014] This object, as well as these and other objects, is a method for estimating the braking operation of a vehicle, the vehicle comprising at least one braking element and at least one braked element of at least one brake of the vehicle, the braking element including at least one force sensor and at least one electronic control unit of the at least one brake, the method comprising: - a step of temporal acquisition by said control unit of at least one force signal generated by said at least one force sensor; - detecting significant temporal changes in said force signal; - processing in said control unit using a customized algorithm of said significant changes in said force signal; - reconstruction of the time moments of activation and deactivation of said brake via said algorithm; - returning, by the control unit, the time moments of brake application and release to an information system and / or an on-board control application and / or a dedicated algorithm for estimating the performance and state of the vehicle's braking system.

[0015] The present invention also discloses a device for estimating the braking actuation of a vehicle, the vehicle comprising at least one braking element and at least one braked element of at least one brake of the vehicle, the braking element comprising at least one force sensor and at least one control unit, the control unit acquiring force signals generated by the at least one force sensor over time, detecting said significant temporal changes of the force signals, processing said significant changes of the force signals using a customized algorithm, reconstructing via said algorithm time moments of brake actuation and release, and returning said time moments of brake actuation and release to an information system and / or an on-board control application and / or a dedicated algorithm for estimating the performance and state of the braking system of the vehicle. [Brief explanation of the drawings]

[0016] Various implementations are illustrated in the accompanying drawings for illustrative purposes and should not be construed as limiting the scope of the present illustrations in any way. Various features of different disclosed embodiments can be combined to form additional embodiments that are part of this example. [Figure 1] 1 shows a schematic representation of a corner of a vehicle suitably configured to estimate the braking effort of the vehicle according to a first embodiment of the present invention; [Figure 2] 1 shows the architecture of a device for estimating braking effort according to a first embodiment of the invention; [Figure 3] 3 shows the architecture of a device for estimating braking effort according to a second embodiment of the invention; [Figure 4]4 shows the architecture of a device for estimating braking effort according to a third embodiment of the invention; [Figure 5] 1 shows the coefficients of the pseudo-convolution function for determining the signal. [Figure 6] The temporal overlap between the signal and the threshold is shown. [Figure 7] FIG. 1 shows a block diagram of an algorithm for estimating braking effort. [Figure 8] A comparison between experimental data and data processed by a braking effort estimation algorithm is shown. [Figure 9] 1 shows a planar layout of a possible embodiment of a brake pad with sensors that can be used for braking effort estimation, with the wear material blocks and possible shock absorbing sub-layers removed for clarity. DETAILED DESCRIPTION OF THE INVENTION

[0017] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof.

[0018] In the drawings, like reference numerals generally identify like elements, unless the context requires otherwise.

[0019] The illustrative embodiments set forth in the detailed description and drawings are not intended to be limiting.

[0020] Typically, components associated with only one corner of the vehicle are shown.

[0021] Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.

[0022] The aspects of the present disclosure, as generally described herein and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are expressly contemplated and present in the present illustrations.

[0023] According to the invention, as shown diagrammatically in Figure 1, at least one corner of the vehicle is suitably equipped with a brake 1 comprising a braked element 2, at least one braking element 3 and at least one braking element 3', in particular two braking elements 3 and 3'.

[0024] Each braking element 3, 3' comprises a block of wearable friction material 4 and a rear support plate 5, typically of metal, between which is interposed at least one force sensor 6, typically of, but not limited to, the piezoelectric ceramic type.

[0025] A cushion layer 7 may be provided between the rear support plate 5 and the friction material block 4 .

[0026] The brake 1 can be either a drum brake or a disc brake with pads.

[0027] In the case described below, reference is made to a disc brake 1 with pads, in which the braked element 2 is a disc and two braking elements 3, 3' act on either side of the disc, consisting of a right-hand pad and a left-hand pad, at least one of which is sensed by at least one force sensor 6. In the case of a drum brake, not shown, there is a drum as the braked element and two brake shoes as braking elements, at least one of which is sensed by at least one force sensor.

[0028] Preferably, the braking element 3, 3' comprises two or more force sensors 6, in particular at least one normal force sensor and / or at least one shear force sensor.

[0029] The force sensor 6 is connected to an electrically isolated circuit 8 located on the side of the rear support plate 5 facing the friction material block 4 .

[0030] The braking element 3 , 3 ′ can also advantageously include at least one temperature sensor 9 connected to the electric circuit 8 .

[0031] The temperature sensor 9 is preferably configured and positioned to acquire the temperature of the rear support plate 5 .

[0032] The electrical circuit 8 has electrical tracks 10' connecting the force sensor 6 and the temperature sensor 9 to an electrical interface connector 10, which transmits the electrical signals generated by the force sensor 6 and the temperature sensor 9 to an electronic control unit 11 of the brake 1.

[0033] Advantageously, one or more corners can be equipped in this way on the vehicle.

[0034] Advantageously, the electronic control unit 11 for braking effort estimation may be one or more electronic control units 11 dedicated individually to each corner of the vehicle, or may be a single superordinate electronic control unit 11 for braking effort estimation for several corners of the vehicle.

[0035] In a first embodiment, shown diagrammatically in FIG. 2, the electronic control unit 11 receives only the electrical signals generated by the force sensor 6 and the temperature sensor 9 .

[0036] The normal and shear forces can be measured using a single force sensor or by a set of sensors distributed on the braking elements 3, 3' and can be used together or alternatively by the electronic control unit 11 to reconstruct the time moments of brake application and release.

[0037] The temperature measured by the temperature sensor 9 and acquired by the electronic control unit 11 is used for compensation purposes to improve the performance of the calculation algorithms in the electronic control unit 11 for estimating the braking effort of the vehicle.

[0038] The control unit 11 processes the changes in the detected force signals using a customized algorithm and reconstructs via the algorithm the time moments of brake application and release and returns this to the information system 19 and / or control application 20 on board the vehicle.

[0039] Advantageously, the electronic control unit 11 of the brake 1 may interact with other sensors 100 installed in the vehicle, which are provided with sensors, means for measuring and / or estimating physical parameters representative of the state of the brake and / or the vehicle.

[0040] Such sensors 100 may include, for example, but are not limited to, a vehicle speed sensor 14, a vehicle acceleration sensor 15, a temperature sensor 16 for the environment outside the vehicle, a temperature sensor 17 for the temperature of the braked element 2, and a vehicle wheel speed and / or angular acceleration sensor 18.

[0041] In a second embodiment, shown diagrammatically in FIG. 3, the electronic control unit 11 acquires the electrical signals generated by the force sensor 6 and the temperature sensor 9 and interacts directly with other sensors installed in the vehicle.

[0042] Advantageously, the vehicle speed, the vehicle acceleration, the ambient temperature outside the vehicle, the temperature of the braked element 2, the speed and / or the angular acceleration of the vehicle wheels can be used together or alternatively to improve the performance of the calculation algorithm in the control unit 11 for estimating the braking effort of the vehicle. Advantageously, the electronic control unit 11 of the brake 1 can interact with a vehicle electronic control unit 12 that is normally equipped on the vehicle.

[0043] In a third embodiment, shown diagrammatically in Figure 4, an electronic control unit 11 acquires the electrical signals generated by the force sensor 6 and the temperature sensor 9 and interacts with other sensors installed in the vehicle via the vehicle's electronic control unit 12.

[0044] Advantageously, the vehicle's electronic control unit 12 acquires signals detected by other sensors installed in the vehicle, compensates them with its own algorithms and forwards them together or alternatively to the control unit 11 to improve the performance of the calculation algorithm for estimating the braking effort of the vehicle.

[0045] In a first preferred embodiment of the present invention, the customized algorithm for processing significant temporal changes in the force signal of the control unit 11 employs an edge detection technique involving the development of a pseudo-convolution over discrete time through a statistical type window and a progressive portion of the signal defined by a sliding threshold buffer, and a comparison of the processed signal with a variable threshold evaluated in real time by image processing techniques determines the definition of the time moments of brake application and release.

[0046] More specifically, the reference signal H as a function of time H(t) detected by the force sensor 6 is processed by a customized algorithm in the control unit 11, where the time-dependent signal convolution technique involves integration over continuous time. Due to the need to deal with discrete sampling and for the purposes of the algorithm, the pseudo-convolution is a statistical type of "H window The detected signal is summed over discrete time by a window (typically Gaussian / Hamming) of fixed size Δ, denoted as "t^-Δ,t^", and a moving buffer of fixed size A over the interval [t^-Δ,t^], denoted as "Raw_[t^-Δ,t^]", with the buffer size typically ranging from 10 ms to 500 ms, preferably from 50 ms to 400 ms. The buffer size determines the temporal detection capability; a larger buffer size provides better performance, but also introduces a larger delay in detection.

[0047] Analytically, the pseudo-convolution is expressed as follows: At time t̂, the pseudo-convolution H(t̂) is calculated.

[0048]

number

[0049]

number

[0050] FIG. 5 shows a schematic diagram of the coefficients of the pseudo-convolution formula.

[0051] Variable threshold assessed in real time using image processing techniques (typically Niblack and Sauvola): The threshold is assessed in real time using signal fluctuations and average values ​​rather than a fixed numerical level.

[0052] Analytically, the adaptation threshold at time t̂ is evaluated as follows:

[0053]

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[0054]

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[0055]

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[0056]

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[0057] especially,

[0058]

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[0059]

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[0060] In this formulation, k and N are hyperparameters of the model that must subsequently be optimized using an appropriate optimization technique.

[0061] where the first coefficient represents the moving average of the raw signal in the buffer of size Δ, and the function o represents the moving standard deviation of the raw signal in the buffer of size Δ.

[0062] The braking action signal is determined by comparing the reference signal H(t) with a threshold Thr(t). Figure 6 shows the time overlap between the signal H(t) and the threshold Thr(t).

[0063] The braking signal is delayed in time by the size of the buffer.

[0064] In a second preferred embodiment of the present invention, the control unit 11 acquires and calibrates at least data from at least one vehicle speed sensor 14 and at least one vehicle acceleration sensor 15, as well as normal and / or shear force data from the force sensor 6, and compares significant changes in the force signals acquired from the force sensor 6 with the calibrated data acquired from the acceleration sensor 15 and with predetermined thresholds to determine the time moments of brake application and release.

[0065] A block diagram of the algorithm is shown in Figure 7.

[0066] At station 200, a customized algorithm in control unit 11 compensates for acceleration values ​​using sensor tilt techniques.

[0067] At station 300, an algorithm integrates the signal from the force sensor 6, evaluates its variation and, if it actually compares with a predetermined threshold at station 301, compares it with the compensated acceleration value from station 200 at station 302.

[0068] If both values ​​exceed a predetermined acceleration threshold, the event is classified as a braking action or braking modulation by 303 .

[0069] If the force sensor signal value exceeds the threshold but the acceleration value does not exceed the threshold, the event is classified as a brake release by 304 .

[0070] Events classified in this way from stations 303 and 304 contribute to the estimated braking action at station 400 .

[0071] FIG. 8 shows a comparison between experimental data and data processed by a braking effort estimation algorithm, confirming the positive results of applying the method of the present invention for braking effort estimation.

[0072] The present invention also discloses a device for estimating the braking effort of a vehicle comprising at least one braking element 3, 3' and at least one braked element 2 of at least one brake 1 of the vehicle, the braking element 3, 3' comprising at least one force sensor 6 and at least one control unit 11, the control unit 11 acquiring force signals generated by the at least one force sensor 6 over time, detecting significant temporal changes in the force signals, processing the significant temporal changes in the force signals using a customized algorithm, reconstructing via the algorithm time moments of brake application and release and returning said time moments of brake application and release to a dedicated information system 19 and / or an on-board vehicle control application 20 and / or algorithm 21 for estimating the performance and state of the braking system.

[0073] In practice, the method for estimating vehicle braking actuation according to the present invention has been found to be particularly advantageous because it is derived using direct measurements of normal and / or shear force signals detected by the intelligent brake pads, and in some embodiments is supplemented by other measurements from other on-board sensors.

[0074] The present invention has the advantage that braking effort can be estimated in real time.

[0075] Braking effort estimation can be advantageously used to reproduce / verify brake pedal actuation, i.e., to signal any undesired changes in brake pedal position and / or improper actuation of the brake assist system.

[0076] Advantageously, the braking effort information can be used for pure monitoring purposes, such as vehicle information 19 and entertainment systems, but also for closed loop feedback applications, such as, but not limited to, control applications 20 BBW (Brake-by-Wire) for electric brakes and EMB (Electromagnetic or Electromechanical Brake) for electromagnetic or electromechanical brakes.

[0077] A significant advantage of the present invention is its ability to provide braking performance information to further algorithms 21 dedicated to estimating braking system performance and status, typically residual torque estimation, ABS intervention, vehicle speed, rotating element temperature, friction element wear estimation, and other algorithms typically developed by the applicant.

[0078] Advantageously, all acquisition and processing algorithms are independent of the type of vehicle and / or brake pads and / or driving style thanks to the self-evaluation of the calibration of the signal thresholds, and therefore advantageously no adjustment actions for different applications are required.Modifications and variations to the method and device for estimating the actuation of vehicle brakes other than those described are of course possible.

[0079] The method for estimating the braking effort of a vehicle's braking elements thus designed is susceptible to numerous modifications and variations, all of which fall within the scope of the inventive concept as defined in the claims.

[0080] In addition, all the details may be replaced with other technically equivalent elements.

[0081] In fact, the materials and systems used can be any according to the requirements and the current state of the art.

Claims

1. A method for estimating the braking operation of a vehicle, the vehicle comprising at least one braking element (3, 3') of at least one brake (1) of the vehicle and at least one braked element (2), the braking element (3, 3') comprising at least one force sensor (6) and at least one electronic control unit (11) of the at least one brake (1), the method comprising: - a step of temporal acquisition by said control unit (11) of at least one force signal generated by said at least one force sensor (6); - detection of significant temporal changes in said force signal; - processing in said control unit (11) using a customized algorithm of said significant changes in said force signal; - a step of reconstruction of the time moments of application and release of said brakes via said algorithm; - returning, by said control unit (11), said time moments of application and release of said brakes to an information system (19) and / or to an on-board control application (20) and / or to a dedicated algorithm (21) for estimating the performance and state of the braking system of said vehicle.

2. 2. A method for estimating braking actuation according to claim 1, characterized in that the braking element (3, 3') comprises a plurality of force sensors (6).

3. 3. A method for estimating braking actuation according to claim 1 or 2, characterized in that the force signal is obtained as an average of the force signals generated by the plurality of force sensors (6).

4. 4. The method of estimating brake actuation according to any one of claims 1 to 3, characterized in that the returning by the control unit (11) of the time moments of the actuation and release of the brakes to the information system (19) and / or the on-board control application (20) and / or the algorithm (21) dedicated to estimating the performance and state of the braking system of the vehicle is performed in real time.

5. A method for estimating braking actuation according to any one of claims 1 to 4, characterized in that it comprises a sensor (100) installed on the vehicle, comprising means for measuring and / or estimating physical parameters representative of the state of the brake (1) and / or the vehicle.

6. 6. The method for estimating braking operation according to claim 1, wherein the sensors (100) include at least one speed sensor (14) of the vehicle, an acceleration sensor (15) of the vehicle, a temperature sensor (16) of the ambient temperature outside the vehicle, a temperature sensor (17) of the braked element (2), and an angular velocity and / or acceleration sensor (18) of the wheels of the vehicle.

7. Method for estimating braking actuation according to any one of claims 1 to 6, characterized in that the control unit (11) is solely dedicated to the corner of the vehicle.

8. Method for estimating braking actuation according to any one of claims 1 to 6, characterized in that the control units (11) are dedicated to several corners of the vehicle.

9. 9. The method of claim 1, wherein the customized algorithm of the significant temporal changes of the force signal of the control unit (11) uses an edge detection technique involving the development of a pseudo-convolution over discrete time through a statistical type window and a progressive portion of the signal defined by a sliding threshold buffer, and the comparison of the processed signal with a variable threshold evaluated in real time using image processing techniques allows the time moments of brake application and release to be defined.

10. Method for estimating braking actuation according to any one of claims 1 to 9, characterized in that the buffer has a size of 10 ms to 500 ms, preferably 50 ms to 400 ms.

11. 9. The method of claim 1, wherein the control unit (11) acquires and calibrates at least data from at least one of the speed sensors (14) of the vehicle and at least one of the acceleration sensors (15) of the vehicle, and the normal force data and / or shear force data from the force sensor (6), and the customized algorithm compares the significant changes in the force signals with the calibrated data of the acceleration sensors (15) and with predetermined thresholds to determine the time moments of brake application and release.

12. 1. A device for estimating the brake application of a vehicle, the vehicle comprising at least one braking element (3, 3') and at least one braked element (2) of at least one brake (1) of the vehicle, the braking element (3, 3') comprising at least one force sensor (6) and at least one control unit (11), the control unit (11) acquiring force signals generated by the at least one force sensor (6) over time, detecting significant temporal changes in the force signals, processing the significant changes in the force signals using a customized algorithm, reconstructing the time moments of the brake application and release via the algorithm, and returning the time moments of the brake application and release to an information system (19) and / or an on-board control application (20) and / or a dedicated algorithm (21) for estimating the performance and state of the braking system of the vehicle.

13. 13. A device for estimating the actuation of a brake according to claim 12, characterized in that it comprises a sensor (100) comprising means for measuring and / or estimating physical parameters representative of the state of the brake (1) and / or the vehicle.

14. 14. A device for estimating braking operation according to claim 12 or 13, characterized in that the sensors (100) include at least one speed sensor (14) of the vehicle, an acceleration sensor (15) of the vehicle, a sensor of ambient temperature outside the vehicle (16), a temperature sensor (17) of the braked element (2), and an angular velocity and / or acceleration sensor (18) of a wheel of the vehicle.

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