An online detection and active compensation method and system for brake drag fault

Abstract

The present application relates to the technical field of automobile chassis braking, and particularly relates to an online detection and active compensation method and system for brake drag failure. The online detection and active compensation method for brake drag failure comprises the following steps: acquiring wheel speed, ambient temperature, brake disc temperature and braking intensity; calculating the theoretical temperature of the brake disc based on a thermodynamic model according to the braking intensity, the wheel speed and the ambient temperature; comparing the theoretical temperature of the brake disc with the brake disc temperature; if the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc is greater than a first preset temperature and the duration is greater than a preset time, then the drag failure is determined; when the drag failure is determined, the lead screw of the brake is driven to push the piston back. The present application realizes early and accurate diagnosis of the drag failure by using the thermodynamic model and multi-sensor data fusion, and avoids hysteresis.

Description

Technical Field

[0001] This invention relates to the field of automotive chassis braking technology, and in particular to an online detection and active compensation method and system for brake drag faults. Background Technology

[0002] Brake drag is a common fault in disc brakes, characterized by incomplete separation of the brake pads from the brake disc after braking, resulting in residual drag torque. Causes include poor piston return in the brake caliper, stuck guide pins, and poor return of brake fluid through the lines. Dragging leads to increased energy consumption, abnormal brake pad wear, risk of brake fade, and brake dust emissions. Currently, drag detection relies primarily on driver perception or visual inspection by maintenance personnel, which is highly reactive and cannot provide early warning or proactive intervention. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention provides an online detection and active compensation method and system for brake drag faults.

[0004] This invention includes the following technical solutions: The first aspect of this invention provides an online detection and active compensation method for brake drag faults, comprising the following steps: It obtains wheel speed, ambient temperature, brake disc temperature, and braking intensity; Based on a thermodynamic model, the theoretical temperature of the brake disc is calculated according to braking intensity, wheel speed and ambient temperature. Compare the theoretical temperature of the brake disc with the actual temperature of the brake disc: if the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc is greater than the first preset temperature and the duration is greater than the preset time, then a dragging fault is determined. When a drag fault is detected, the lead screw of the drive brake pushes the piston back.

[0005] Furthermore, the thermodynamic model is calibrated in the following manner: Real vehicle tests were conducted under different ambient temperatures, different wheel speeds, and different braking intensities to obtain the measured temperature of the brake discs. Establish a mapping table between the measured temperature of the brake disc and the braking intensity, wheel speed, and ambient temperature.

[0006] Furthermore, the first preset temperature is 20-40℃; and / or the preset time is 1-3 minutes.

[0007] A second aspect of the present invention provides an online detection and active compensation system for brake drag faults, comprising: The data acquisition module is used to obtain wheel speed, ambient temperature, brake disc temperature, and braking intensity. The electronic control module has a pre-stored thermodynamic model, which is configured to calculate the theoretical temperature of the brake disc based on braking intensity, wheel speed and ambient temperature. The electronic control module is also configured to: determine a dragging fault when the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc is greater than a first preset temperature and the duration is greater than a preset time. The electronic control module is also configured to send a compensation instruction to the compensation execution mechanism after determining a dragging fault. The compensation actuator is used to drive the lead screw to push the piston back to release residual pressure or jamming.

[0008] Furthermore, the acquisition module includes a first temperature acquisition unit, a wheel speed acquisition unit, a second temperature acquisition unit, and a braking intensity acquisition unit; The first temperature acquisition unit is located in the non-direct heat radiation area of ​​the brake caliper body and is used to acquire the temperature of the brake disc. The wheel speed acquisition unit is arranged at the wheel hub and is used to acquire the wheel speed. The second temperature acquisition unit is located at the front water tank crossbeam of the vehicle and is used to collect ambient temperature. The brake pressure sensor of the brake intensity acquisition unit is installed at the inlet of the master cylinder or wheel cylinder to measure the brake pressure. The brake intensity acquisition unit obtains the brake intensity based on the brake pressure.

[0009] Furthermore, the first temperature acquisition unit uses a wireless radio frequency temperature tag, which is affixed to the outer wall of the brake caliper body.

[0010] Furthermore, the compensation actuator is integrated inside the brake caliper and includes a micro stepper motor and a lead screw and nut mechanism, with the front end of the lead screw abutting against the rear end face of the brake caliper piston.

[0011] Furthermore, the compensation actuator also includes a planetary reduction gear set, and the micro stepper motor drives the lead screw and nut mechanism through the planetary reduction gear set to achieve piston displacement control.

[0012] Furthermore, it also includes: The closed-loop verification module is configured to continue monitoring the brake disc temperature after the compensation actuator operates. If the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc converges to the threshold range, the compensation is deemed successful; otherwise, secondary compensation is triggered or a mechanical jamming alarm is triggered.

[0013] Furthermore, it also includes an alarm module, which is integrated into the vehicle's dashboard to provide a mechanical jamming alarm.

[0014] By adopting the above technical solution, the present invention has the following advantages: Online real-time monitoring: By fusing thermodynamic models with multi-sensor data, early and accurate diagnosis of drag faults can be achieved, avoiding lag.

[0015] Proactive compensation: Shifts from passive repair to proactive maintenance, automatically eliminating minor delays without manual intervention, thus improving the user experience.

[0016] Energy saving and consumption reduction: Effectively reduces energy loss caused by dragging, which is particularly significant for improving the range of electric vehicles.

[0017] Extend lifespan: Prevent abnormal wear of brake pads and brake discs, reducing maintenance costs.

[0018] Safety warning: Timely alarm in case of serious malfunction to ensure driving safety.

[0019] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of an online detection and active compensation method for brake drag fault in an embodiment of the present invention; Figure 2 This is a schematic diagram of the brake in an embodiment of the present invention.

[0022] In the diagram, 1-brake caliper body, 2-electronic control module, 3-first temperature acquisition unit, 4-wheel speed acquisition unit, 5-compensation actuator. Detailed Implementation

[0023] The following description provides many different embodiments or examples for implementing various features of the invention. The elements and arrangements described in the specific examples below are only for concise expression of the invention and are merely examples, not intended to limit the invention.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Combination Figure 1 As shown in the figure, this application provides an online detection and active compensation method for brake drag fault, including the following steps: Collect data on wheel speed, ambient temperature, brake disc temperature, and braking intensity; Based on a thermodynamic model, the theoretical temperature of the brake disc is calculated according to braking intensity, wheel speed and ambient temperature. Compare the theoretical temperature of the brake disc with the actual temperature of the brake disc: if the brake disc temperature is greater than the theoretical temperature of the brake disc and the duration is longer than the preset time, then a dragging fault is determined. When a drag fault is detected, the lead screw of the drive brake pushes the piston back.

[0026] The thermodynamic model is calibrated in the following manner: Real vehicle tests were conducted under different ambient temperatures, different wheel speeds, and different braking intensities to obtain the measured temperature of the brake discs. Establish a mapping table between the measured temperature of the brake disc and the braking intensity, wheel speed, and ambient temperature.

[0027] The preset time is 1-3 minutes.

[0028] This application also provides an online detection and active compensation system for brake drag faults.

[0029] 1. Physical implementation and signal processing of the acquisition module The acquisition module is responsible for acquiring high-fidelity raw data. It specifically includes the following sub-units: First temperature acquisition unit (brake disc temperature monitoring): Traditional contact thermocouples or infrared sensors have a short lifespan in high-temperature, high-vibration, and dusty wheel-end environments, and wiring is difficult. In this embodiment, a passive ultra-high frequency (UHF) radio frequency temperature tag (RFID tag) is preferably used.

[0030] Installation location: Combined Figure 2As shown, the first temperature acquisition unit 3 is affixed to the outer wall of the brake caliper 1 in a non-direct heat radiation area. The reason for choosing the outer wall of the brake caliper 1 instead of the brake disc itself is that the brake disc is in a high-speed rotating state, making it difficult to directly install the label and causing it to fall off due to centrifugal force; while the temperature of the side wall of the brake caliper 1 is highly linearly correlated with the temperature of the brake disc, and avoids the direct path of the hot airflow thrown out by the brake disc, which can effectively reflect the heat storage state of the brake disc without being disturbed by instantaneous frictional heat.

[0031] Working principle: This wireless radio frequency temperature tag requires no battery and obtains energy from the electromagnetic field emitted by the vehicle-mounted RFID reader. The reader antenna is installed inside the wheel arch, directly facing the tag. When the vehicle starts, the reader periodically (e.g., once per second) emits radio frequency pulses, activating the chip inside the tag. The chip measures the impedance change of the tag antenna (impedance changes linearly with temperature) and modulates the temperature data, reflecting it back to the reader. This method achieves contactless power supply and data transmission, greatly improving the system's reliability.

[0032] Signal processing: Since wheel speed rotation may cause Doppler effect interference, the system adopts an adaptive filtering algorithm to remove outliers caused by signal attenuation, and performs moving average filtering on 10 consecutive sampling points to obtain a stable brake disc temperature.

[0033] Wheel speed acquisition unit: Traditional magnetoelectric or Hall effect wheel speed sensors are used. Combined with... Figure 2 As shown, wheel speed acquisition unit 4 is integrated into the wheel hub bearing unit, and the probe of wheel speed acquisition unit 4 is fixed to the steering knuckle. This unit outputs a square wave pulse signal, and the electronic control module calculates the wheel speed V (unit: km / h or r / min) by measuring the pulse frequency. Under coasting conditions, the rate of change of wheel speed (deceleration) is also an auxiliary parameter for judging the vehicle's driving resistance.

[0034] Second temperature acquisition unit (ambient temperature monitoring): Using an NTC thermistor or digital temperature sensor (such as DS18B20), it is installed on the front water tank crossbeam of the vehicle, avoiding ground heat radiation and engine compartment waste heat, to collect accurate intake air temperature as ambient temperature.

[0035] Brake pedal status switch: Connect the brake light switch or brake pedal travel sensor to obtain the brake pedal status signal (0: released, 1: depressed).

[0036] Braking intensity acquisition unit: The braking intensity acquisition unit includes a braking pressure sensor, which is installed at the inlet of the master cylinder or wheel cylinder to measure the braking pressure. The braking intensity acquisition unit calculates the braking intensity based on the braking pressure. It is worth noting that the conversion between braking pressure and braking intensity is known to those skilled in the art and will not be elaborated upon here.

[0037] 2. Architecture of Electronic Control Module (ECU) The electronic control module (ECU) can be integrated into the vehicle's electronic braking system (EBS) or electro-hydraulic braking system (EHB); it can also exist as a standalone embedded system. Figure 2 As shown, electronic control module 2 (please specify the location of the electronic control module). Electronic control modules typically employ automotive-grade microcontroller units (MCUs), such as processors based on the ARM Cortex-R series, which feature floating-point units (FPUs) and a rich set of peripheral interfaces.

[0038] Storage unit: Flash memory: used to store calibrated thermodynamic model look-up tables, program code, and non-volatile fault codes (DTCs).

[0039] RAM: Used for runtime data storage, including real-time acquired temperature sequences, rotation speed sequences, and intermediate variables for calculation.

[0040] Processing Unit (CPU): Responsible for executing the core algorithms. Includes: Operating condition arbitration logic: Determine whether the vehicle is in a valid monitoring window of "coasting or cruising and the brakes have been released".

[0041] Fault determination logic: Execute temperature difference comparison and time accumulation logic.

[0042] PWM / Stepper Driver Module: Generates pulse sequences to control the stepper motor.

[0043] 3. Precision mechanical design of the compensation execution mechanism Combination Figure 2 As shown, the compensation actuator 5 is the key actuator for achieving active compensation. It is integrated inside the brake caliper and replaces the dust cover of the traditional caliper.

[0044] Miniature stepper motor: Uses permanent magnet or hybrid stepper motor with a step angle of 1.8 degrees, has high holding torque, and can lock position even under severe vehicle vibration.

[0045] Planetary reduction gear set: In order to convert the tiny angular displacement of the stepper motor into extremely precise axial linear displacement and increase the thrust, a planetary reduction gear set is introduced into the system.

[0046] Transmission ratio: Set to 100:1 to 200:1. That is, for every 100 revolutions of the motor, the output shaft rotates once.

[0047] Function: Significantly improves control accuracy and output torque. The angular displacement error output by the stepper motor is amplified by the reduction ratio and transformed into an extremely small linear displacement error, thereby achieving micron-level (μm) control accuracy.

[0048] Lead screw and nut mechanism: A ball screw or sliding screw is used. The front end (push rod end) of the screw directly abuts against the rear end face of the brake caliper piston. The rear end of the screw is fixedly connected to the output shaft of the planetary gear set.

[0049] Lead design: The lead screw lead is set to 2mm. Combined with a reduction ratio of 100:1, the lead screw advances 0.02mm (20μm) for every revolution of the motor. For every step (1.8 degrees) of the motor, the lead screw advances 0.02×(1.8 / 360)=0.0001mm (0.1μm).

[0050] Self-locking feature: Select a trapezoidal threaded screw with self-locking function or install an electromagnetic brake at the end of the motor to ensure that the piston position will not retract due to the reaction force of the brake fluid after the motor is powered off, thus ensuring the stability of braking performance.

[0051] Displacement sensor (optional): In high-end applications, an LVDT (Linear Variable Differential Transformer) or Hall effect displacement sensor can be integrated at the end of the lead screw to provide real-time feedback on the actual displacement of the lead screw, forming a closed-loop control to prevent the lead screw from jamming or spinning freely.

[0052] 4. Closed-loop verification and alarm module Closed-loop verification module: Logically integrated into the electronic control module. After issuing a compensation command and completing the action, this module starts a timer (e.g., 30 seconds) to continuously monitor the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc. If the temperature difference ΔT gradually decreases and returns to within the normal threshold (e.g., ±5℃), the "compensation successful" flag is set; if the temperature difference does not change or even increases, a mechanical jamming alarm is triggered.

[0053] Alarm module: Interacts with the instrument panel or central control screen via CAN bus. Mechanical jamming alarm is divided into two levels: Level 1 alarm is "Slight jamming, automatically adjusted", illuminating a yellow warning light; Level 2 alarm is "Severe jamming, please check", illuminating a red warning light and accompanied by an audible prompt.

[0054] 5. Depth calibration and construction of thermodynamic models One of the core innovations of this invention lies in using a thermodynamic model to calculate the "theoretical temperature of the brake disc." The temperature change of the brake disc is a complex dynamic process, influenced by air convection, thermal radiation, heat generated by braking friction, and heat dissipation through wheel hub conduction.

[0055] (1) Application of the law of conservation of energy The thermal balance equation for the brake disc can be expressed as: ; in, For brake disc quality, For the specific heat capacity of the brake disc, For the rate of temperature change, For frictional heat generation power, For convective heat transfer power, For thermal radiation power, For heat dissipation through conduction.

[0056] (2) Construction of thermodynamic model Since the computational load of solving the above partial differential equations in real time in embedded systems is too large and the parameters are difficult to measure accurately, this invention adopts a black box model + lookup table method for engineering implementation.

[0057] Step 1: Set up the test platform Select the target vehicle model and drill a hole in the left front brake disc to insert a type K thermocouple as a temperature reference. Install an RFID tag on the brake caliper. Connect calibration tools such as INCA or CANape to record wheel speed, brake pressure, and ambient temperature signals on the CAN bus.

[0058] Step 2: Design the test case matrix Covering all possible combinations of operating conditions: Ambient temperature: -20℃, 0℃, 25℃, 40℃, 60℃.

[0059] Wheel speeds: 30km / h, 60km / h, 90km / h, 120km / h.

[0060] Braking intensity (deceleration): 0.1g, 0.3g, 0.6g, 0.8g.

[0061] Driving cycle: includes multiple braking and coasting processes.

[0062] Step 3: Data Collection The driver operates the vehicle according to the test matrix. For example, in an environment of 25°C, the vehicle is braked from 100 km / h to 50 km / h with full force, and then the brake pedal is fully released, allowing the vehicle to coast freely. At this time, the brake discs begin to cool. The system records the measured brake disc temperature, wheel speed, and ambient temperature per second for 500 seconds from the moment the pedal is released.

[0063] Step 4: Data Processing and Mapping Table Generation The calibration engineer post-processed the collected data. The braking intensity (peak deceleration) at the instant the brakes were released was extracted as the initial characteristic parameter for this cooling process.

[0064] Create a three-dimensional array (mapping table): X-axis: Ambient temperature (5°C resolution).

[0065] Y-axis: Wheel speed (resolution 10km / h).

[0066] Z-axis: Peak braking intensity immediately after braking ends (resolution 0.1g).

[0067] The values ​​in the array represent the theoretical temperatures of the corresponding brake discs.

[0068] Interpolation algorithms (such as bicubic interpolation) are used to fill in the data for all grid points. For untested extreme conditions, extrapolation or conservative values ​​are used. The resulting massive data table is then written to the Flash memory of the electronic control module.

[0069] 6. Self-learning optimization of the model Considering that brake disc wear and friction pad aging can lead to changes in heat capacity and heat dissipation coefficient, the system also features an online self-learning function. During normal driving periods without detected drag, the system periodically compares theoretical and measured temperatures. If a system deviation is detected (e.g., measured temperatures are consistently 5°C lower), the system automatically fine-tunes the values ​​in the mapping table, achieving model self-calibration and improving the accuracy of long-term monitoring.

[0070] Detailed flow of software control logic The following section describes the program execution logic in the electronic control module in detail, using a specific software flowchart.

[0071] (1) Main loop and interrupt service The system software uses a foreground / background system or an RTOS (real-time operating system).

[0072] 10ms cycle task: Read sensor data and update global variables such as wheel speed and temperature.

[0073] 100ms cycle task: Performs operating condition judgment, thermodynamic model calculation, and lag judgment logic.

[0074] Event-triggered task: When a delay is detected, a compensation task is triggered.

[0075] (2) Arbitration logic for the "coasting / cruising with no braking" condition This is a prerequisite for system startup and must be strictly defined; otherwise, it may lead to misjudgment.

[0076] The logical expression is: IF(BrakeSwitch == OFF) AND (BrakePressure<0.3MPa) AND (VehicleSpeed>30km / h) AND (CruiseControlActive == TRUE ORThrottlePedalPosition == 0) The system only enters "monitoring activation state" when all the above conditions are met simultaneously and last for more than 5 seconds. This excludes the transition phase when the driver frequently applies the brakes, drives at low speeds, or has just pressed the brake pedal.

[0077] (3) Delay fault determination sub-process Once the monitoring is activated, the system executes the following loop: Read data: Read the current ambient temperature, wheel speed, and braking intensity.

[0078] Lookup table calculation: Read the current braking intensity historical buffer and obtain the peak value of the most recent effective braking. Using ambient temperature, wheel speed, and braking intensity as indexes, look up the table to obtain the theoretical brake disc temperature.

[0079] Calculate the temperature difference (DeltaT): ΔT = brake disc temperature - theoretical brake disc temperature.

[0080] Threshold temperature comparison: IF(\DeltaT>T_{threshold}). Here, the first preset temperature (threshold) is not a fixed 30℃, but a variable that varies with vehicle speed. For example, at high speeds, air cooling is stronger, theoretically cooling down faster, and the allowable value of ΔT is smaller; at low speeds, the allowable value of ΔT is larger. The setting range is 20-40℃.

[0081] Timer accumulation: If ΔT > Tthreshold, then start or accumulate the timer. If (Timer_{drag}>Time_{threshold}) (the preset time (Time_threshold) is 1-3 minutes), then it is officially determined to be a dragging failure.

[0082] De-vibration processing: To prevent temperature jumps caused by road bumps or instantaneous airflow interference, the system introduces hysteresis comparison. The fault determination threshold (e.g., 30℃) is higher than the fault resolution threshold (e.g., 10℃).

[0083] 7. Proactive Compensation Execution Sub-process Once a drag fault is detected, the electronic control module controls the compensation actuator via the drive circuit: Initialization: Enable the stepper motor driver and release the brake (if applicable).

[0084] Determine the number of steps: Dynamically determine the retraction amount based on the severity of the drag (the magnitude of ΔT). For slight drag (30℃ < ΔT < 40℃), retract 0.1mm; for severe drag, retract 0.5mm. Convert to motor steps: Steps = (Retraction distance / Leadscrew lead) × Reduction ratio × Stepper motor steps / revolution. For example, a retraction of 0.2mm, a lead of 2mm, a reduction ratio of 100, and a step count of 20,000 steps.

[0085] Action executed: The MCU outputs a PWM pulse sequence. An S-shaped acceleration / deceleration curve is used to control the motor's start and stop, preventing mechanical shock. For example, the motor first accelerates to its rated speed, runs a certain number of steps, and then decelerates to a stop.

[0086] Position locking: After the pulse is sent, keep the motor windings energized (or close the electromagnetic brake) to lock the lead screw in the current position. At this time, the piston is physically pushed backward, the gap between the brake pads and the brake disc increases, and the residual pressure is released.

[0087] 8. Closed-loop verification sub-process Within 30 seconds of the compensation action being completed, the system enters verification mode: Monitoring convergence: Continue calculating ΔT. Under normal circumstances, due to the elimination of additional frictional heat sources, the rate of temperature decrease of the brake disc will be slower, or even rapidly approach the theoretical temperature of the brake disc because it is no longer heated, thus reducing ΔT.

[0088] Successful determination: If ΔT < the first preset temperature (e.g., 5℃), the compensation is considered successful. The system records this event (log) and briefly displays "Brake system optimized" on the instrument panel before turning off the indicator light.

[0089] Failure handling: Secondary compensation: If ΔT is still greater than the first preset temperature (e.g., 5℃), but has decreased, the system can try to drive the lead screw back by 0.1mm again (the total back-off amount shall not exceed the upper limit of 0.5mm).

[0090] Serious Alarm: If secondary compensation is ineffective, or if the initial ΔT > 80℃ (indicating severe mechanical jamming), the system determines it to be a hardware fault. Further automatic compensation will be immediately stopped (to prevent excessive retraction from causing initial brake failure), and a highest-priority alarm signal will be sent to the instrument panel via the CAN bus, illuminating the red brake warning light and prompting the driver to "stop immediately for inspection." Simultaneously, the system will limit cruise control and recommend reducing vehicle speed.

[0091] Example 1: Simulation of typical application scenarios To better understand the working principle of this invention, three typical driving scenarios are listed below to describe the system's response process in detail.

[0092] Scenario 1: Slight sluggishness after a long downhill section of the highway Background: A fully loaded SUV is cruise-charging at 100 km / h on the highway. Encountering a 5-kilometer downhill stretch, the driver lightly taps the brake pedal several times to maintain speed, then releases the pedal to resume cruise control.

[0093] System response: Monitoring Activation: With vehicle speed stabilized at 100km / h, cruise control activated, and brake pedal released, the system enters monitoring mode.

[0094] Model calculation: Ambient temperature 30℃. Most recent braking intensity 0.15g. From the table, the theoretical brake disc temperature (Tdisc_theory) is 180℃.

[0095] Anomaly detected: The brake disc temperature (Tdisc_meas) measured by RFID is 190℃.

[0096] Fault diagnosis: System analysis suggests that under normal air cooling conditions, the brake disc temperature should drop to around 180°C relatively quickly. However, the actual measured brake disc temperature was 190°C, indicating that the brake disc is being continuously heated by the brake pads (the delay leads to additional frictional heat generation).

[0097] Continuous monitoring: This temperature difference of 35°C lasted for 2 minutes.

[0098] Active compensation: The system determines that there is slight drag. The drive screw retracts by 0.2mm.

[0099] Verification: After compensation, the brake pads detached from the brake disc, the "thermal bridge" disappeared, and the brake disc temperature drop rate returned to normal. After 30 seconds, ΔT converged to 3℃. The system determined that the compensation was successful.

[0100] Scenario 2: Piston sticking caused by repeated braking in congested urban traffic. Background: The vehicle is driving in congested urban traffic, with frequent stops and starts. The driver habitually half-presses the pedal. After the last stop, the driver fully releases the pedal to start again, but feels the vehicle is sluggish and accelerates slowly.

[0101] System response: Monitoring Activation: The vehicle accelerates from a standstill to 40 km / h, then the accelerator is released, and the vehicle enters a coasting state. The system is activated.

[0102] Model calculation: Ambient temperature 25℃. Most recent braking intensity 0.8g (emergency braking). From the table, the theoretical brake disc temperature is 250℃.

[0103] Anomaly detected: The measured brake disc temperature was 280℃.

[0104] Fault diagnosis: After 1.5 minutes, it is determined to be a lag.

[0105] Active compensation: The system determines that there is a relatively serious jamming (possibly due to the piston being stuck by dirt). The drive screw retracts by 0.5mm (maximum stroke).

[0106] Verification: A slight metallic knocking sound was heard (piston returning to its original position), followed by a significant increase in vehicle coasting distance. Temperature monitoring showed that the brake disc temperature decreased rapidly. The driver felt the vehicle become lighter and more responsive.

[0107] Scenario 3: Troubleshooting and Fault Escalation in Extreme Situations Background: The vehicle was driving through water and had just passed a section of road with deep water.

[0108] System response: Monitoring activated: After exiting the water, at a speed of 60km / h, cruise control is activated.

[0109] Anomaly detected: Ambient temperature 28℃. Theoretical brake disc temperature = 120℃. However, due to a large amount of water film adhering to the brake disc, the evaporation and heat absorption resulted in a measured brake disc temperature of 80℃.

[0110] Intelligent Filtering: The system detects a sudden drop in brake disc temperature within a very short time (characteristic of water film evaporation) and slight fluctuations in the wheel speed signal exhibiting hydroplaning characteristics. The system temporarily disables the drag judgment logic and marks it as "wading cooling mode".

[0111] Normal operation resumed: After 30 seconds, the moisture evaporated completely, and the measured temperature quickly rose back to 115℃. The system was then unblocked.

[0112] Fault escalation: Assuming that in the above scenario, after the system drives the lead screw to retract by 0.5mm, the temperature difference still exists (ΔT=38℃), and the vehicle exhibits obvious deviation.

[0113] System Response: The system determines the problem to be a mechanical hardware malfunction (e.g., a guide pin that is corroded and stuck). The system will not attempt further compensation (to prevent damage to the brake clearance). A level two alarm is immediately triggered, the instrument panel displays "Brake system malfunction, please repair immediately," and a red warning light illuminates. Simultaneously, the system notifies the ESP system to adjust the brake force distribution during the next braking maneuver to compensate for insufficient braking force on the right side.

[0114] Example 2: Technical Advantages and Effect Verification Compared with the prior art, the embodiments of the present invention have the following significant advantages: High-precision non-contact temperature monitoring: The use of RFID wireless temperature measurement technology solves the problems of difficult temperature measurement of rotating parts and easy damage of wired sensors. The tag directly reflects the temperature of the brake caliper body and indirectly but stably characterizes the thermal state of the brake disc, avoiding the shortcomings of infrared sensors being blocked by mud and sunlight.

[0115] Intelligent diagnosis based on thermodynamic models: This invention abandons the simple threshold comparison method and introduces a comprehensive consideration of ambient temperature, vehicle speed, and braking history. For example, the same measured brake disc temperature of 150°C has completely different meanings in high-speed coasting in winter and urban coasting in summer. The model of this invention can distinguish between "normally high temperature" and "abnormal dragging temperature drop," with an extremely low false alarm rate.

[0116] Micrometer-level active compensation mechanism: Traditional solutions only provide an alarm and require in-store repair. This invention, through a miniature stepper motor and precision lead screw, achieves active micro-adjustment of the piston position. A retraction amount of 0.1~0.5mm is sufficient to eliminate residual pressure without causing excessive brake pedal travel or insufficient braking force. The planetary gear reduction mechanism ensures sufficient thrust to overcome the elasticity or jamming resistance of the piston seal.

[0117] Closed-loop verification and security assurance: The system incorporates a closed-loop logic of "drug administration-observation-feedback," commonly found in medical devices. After compensation, the system doesn't ignore the issue but continues to monitor temperature changes. If compensation is ineffective, the system promptly mitigates the damage and escalates the alarm, ensuring driving safety. This "hardware-software integration" design approach significantly enhances the system's robustness.

[0118] Energy saving and economy: Brake drag leads to increased fuel consumption. This invention can eliminate this hidden wear in real time, resulting in significant economic benefits for commercial fleets or frequently used ride-hailing vehicles. Simultaneously, it reduces abnormal wear on brake discs and friction pads, extending maintenance intervals.

[0119] Comparison of experimental data: The system of this invention was verified on a test vehicle equipped with this invention on a rotary drum test bench at a certain OEM factory: Control group (no system): Simulated drag failure (artificially set piston return clearance reduced by 0.3mm). In the 120km / h coasting test, the coasting distance was shortened by 25% compared to the normal state, the brake disc temperature was 32℃ lower than the normal state at the end of the coasting, and the fuel consumption (equivalent) increased by 8%.

[0120] Experimental group (with system): The same drag fault was simulated. The system detected the fault 90 seconds after the start of coasting and immediately drove the lead screw to retract by 0.3mm. The subsequent coasting distance recovered to 98% of the normal level, and the brake disc temperature difference converged to within 2℃.

[0121] Road testing: After 10,000 kilometers of comprehensive road condition testing, the system triggered compensation actions 12 times, 11 of which were successful, and one triggered a level-two alarm due to severe corrosion of the guide pin. No false alarms occurred.

[0122] The online detection and active compensation method and system for brake drag faults provided by this invention fills the technological gap in self-diagnosis and self-repair of micro-drag faults in vehicles during operation through innovative wireless sensing technology, high-precision thermodynamic modeling, precise mechanical actuators, and closed-loop logic control. This system not only effectively reduces vehicle energy consumption and extends the life of braking components, but more importantly, it eliminates the fire hazard caused by brake overheating, improving the vehicle's active safety and intelligence level. It is particularly suitable for future advanced driver assistance systems (ADAS) and autonomous vehicles, providing them with reliable chassis health status management.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0124] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0125] All terms used in this invention (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this invention pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0126] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for online detection and active compensation of brake drag fault, characterized in that, Includes the following steps: It obtains wheel speed, ambient temperature, brake disc temperature, and braking intensity; Based on a thermodynamic model, the theoretical temperature of the brake disc is calculated according to braking intensity, wheel speed and ambient temperature. Compare the theoretical temperature of the brake disc with the actual temperature of the brake disc: if the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc is greater than the first preset temperature and the duration is greater than the preset time, then a dragging fault is determined. When a drag fault is detected, the lead screw of the drive brake pushes the piston back.

2. The online detection and active compensation method for brake drag fault according to claim 1, characterized in that, The thermodynamic model is calibrated in the following manner: Real vehicle tests were conducted under different ambient temperatures, different wheel speeds, and different braking intensities to obtain the measured temperature of the brake discs. Establish a mapping table between the measured temperature of the brake disc and the braking intensity, wheel speed, and ambient temperature.

3. The online detection and active compensation method for brake drag fault according to claim 1, characterized in that, The first preset temperature is 20-40℃; and / or the preset time is 1-3 minutes.

4. An online detection and active compensation system for brake drag faults, characterized in that, include: The data acquisition module is used to obtain wheel speed, ambient temperature, brake disc temperature, and braking intensity. The electronic control module has a pre-stored thermodynamic model, which is configured to calculate the theoretical temperature of the brake disc based on braking intensity, wheel speed and ambient temperature. The electronic control module is also configured to: determine a dragging fault when the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc is greater than a first preset temperature and the duration is greater than a preset time. The electronic control module is also configured to send a compensation instruction to the compensation execution mechanism after determining a dragging fault. The compensation actuator is used to drive the lead screw to push the piston back to release residual pressure or jamming.

5. The online detection and active compensation system for brake drag fault according to claim 4, characterized in that, The acquisition module includes a first temperature acquisition unit, a wheel speed acquisition unit, a second temperature acquisition unit, and a braking intensity acquisition unit; The first temperature acquisition unit is located in the non-direct heat radiation area of ​​the brake caliper body and is used to acquire the temperature of the brake disc. The wheel speed acquisition unit is arranged at the wheel hub and is used to acquire the wheel speed. The second temperature acquisition unit is located at the front water tank crossbeam of the vehicle and is used to collect ambient temperature. The brake pressure sensor of the brake intensity acquisition unit is installed at the inlet of the master cylinder or wheel cylinder to measure the brake pressure. The brake intensity acquisition unit obtains the brake intensity based on the brake pressure.

6. The online detection and active compensation system for brake drag fault according to claim 5, characterized in that, The first temperature acquisition unit uses a wireless radio frequency temperature tag, which is affixed to the outer wall of the brake caliper body.

7. The online detection and active compensation system for brake drag fault according to claim 4, characterized in that, The compensation actuator is integrated inside the brake caliper and includes a micro stepper motor and a lead screw and nut mechanism. The front end of the lead screw abuts against the rear end face of the brake caliper piston.

8. The online detection and active compensation system for brake drag fault according to claim 7, characterized in that, The compensation actuator also includes a planetary reduction gear set, and the micro stepper motor drives the lead screw and nut mechanism through the planetary reduction gear set to achieve piston displacement control.

9. The online detection and active compensation system for brake drag fault according to claim 4, characterized in that, Also includes: The closed-loop verification module is configured to continue monitoring the brake disc temperature after the compensation actuator operates. If the temperature difference between the brake disc temperature and the theoretical temperature of the brake disc converges to the threshold range, the compensation is deemed successful; otherwise, secondary compensation is triggered or a mechanical jamming alarm is triggered.

10. The online detection and active compensation system for brake drag fault according to claim 9, characterized in that, It also includes an alarm module, which is integrated into the vehicle's dashboard to provide a mechanical jamming alarm.

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