Static calibration method for brake pedal of in-vehicle pull-wire motor based on travel measurement

Abstract

The application provides a kind of static calibration method of brake pedal of vehicle-mounted pull wire motor based on travel measurement, by introducing the joint measurement mechanism of displacement sensor and tension sensor, and combining data analysis and control optimization strategy, the overall perception of brake pedal movement state can be realized, by constructing "displacement-tension" relationship curve, based on the collected data to extract maximum stroke, idle stroke, rebound force and other key parameters, to develop a more realistic working condition motor control strategy, improve the response consistency and controllability of brake system, avoid the brake force deviation caused by misjudgment pedal position. The technical content improves the accuracy and stability of brake response, especially in complex road conditions or emergency braking scene, significantly enhances the driving safety. Through the combination of sensor configuration, key parameter extraction and intelligent control strategy, the control error problem caused by the uncertainty of brake pedal characteristics in the traditional AEBS rear-mounted scheme is effectively solved.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a static calibration method for a vehicle-mounted cable motor brake pedal based on travel measurement. Background Technology

[0002] As a core control component of the automotive braking system, the brake pedal is a crucial interface for the driver to control the vehicle's braking through mechanical or hydraulic transmission. Through its linkage with components such as the master cylinder, brake lines, and brake pads, it converts the driver's pedal force into braking force, directly impacting driving safety and braking response characteristics. With the development of the automotive industry, the structural design of the brake pedal has been continuously optimized, but its basic function has always revolved around "precisely transmitting braking intent." Especially with the rise of autonomous driving and intelligent driver assistance technologies, the brake pedal not only needs to meet the requirements of manual operation but also needs to adapt to the mechanical intervention control of the automatic braking system, becoming a vital bridge connecting manual driving and automatic braking.

[0003] Brake pedals in different car models exhibit significant differences in characteristics due to variations in design goals, vehicle structure, and braking system configuration. These differences are primarily reflected in the following aspects: First, structural parameters differ, including variations in leverage ratios and fulcrum positions, leading to variations in braking performance under the same pedal force. Second, stroke parameters differ; the maximum stroke length and the idle stroke (the ineffective movement distance before generating effective braking force) are inconsistent, with some models having an excessively high idle stroke ratio, affecting braking response speed. Third, mechanical characteristics differ; the rebound force exhibits non-linear changes and a large fluctuation range, influenced by factors such as spring stiffness and friction coefficient, resulting in significant differences in the reverse force under the same displacement. These differences give brake pedals highly individualized braking characteristics, and without targeted adaptation, braking control precision can easily decrease.

[0004] In the aftermarket for autonomous driving and intelligent driver assistance technologies, Automatic Emergency Braking Systems (AEBS) often simulate driver pedal action using a cable-driven motor, which pulls the brake pedal via a cable to achieve automatic braking. However, existing cable-driven motors mostly employ a uniform control strategy, failing to consider the characteristics of brake pedals in different vehicle models: when faced with a pedal with high rebound force, insufficient output force may lead to braking failure; when faced with a pedal with short travel, over-response may cause false braking; simultaneously, nonlinear rebound force and travel differences can cause a mismatch between the control logic and the actual pedal state, resulting in braking delays and poor system stability. Therefore, existing control strategies cannot adapt to the diverse brake pedal characteristics of different vehicle models, making it difficult to meet the braking accuracy and safety requirements of aftermarket AEBS. Summary of the Invention

[0005] This application provides a static calibration method for vehicle-mounted cable motor brake pedals based on stroke measurement, in order to solve the problem that existing control strategies cannot adapt to the characteristics of brake pedals in diverse vehicle models and cannot meet the requirements of aftermarket AEBS for braking accuracy and safety.

[0006] This application provides a static calibration method for a vehicle-mounted cable motor brake pedal based on travel measurement, the method comprising:

[0007] Install the cable motor, displacement sensor, and tension sensor on the brake pedal linkage mechanism according to the preset positions;

[0008] Start the wire pull motor, displacement sensor, and force sensor, and initialize them;

[0009] Under the control of the controller, the cable motor pulls the brake pedal at a preset speed to obtain stroke data and tension data;

[0010] The controller plots a displacement-tension relationship curve based on the collected stroke data and tension data, and extracts key parameters from the relationship curve. The key parameters include idle stroke, maximum effective stroke, rebound force, and fluctuation range.

[0011] The key parameters are analyzed to obtain calibration results, and the calibration results are input into the automatic emergency braking system.

[0012] The automatic emergency braking system determines the control strategy for the cable motor based on the calibration results.

[0013] In some possible implementations, the method includes:

[0014] After starting the cable motor, displacement sensor, and tension sensor and initializing, the traction speed and direction are determined according to the vehicle model and calibration requirements;

[0015] The controller starts the cable motor to perform traction operation based on the traction speed and direction, and records the time.

[0016] When the stopping conditions are met, the traction operation is stopped.

[0017] In some possible implementations, the method further includes:

[0018] When the controller starts the cable motor to perform traction operation based on the traction speed and direction, it collects the displacement signal x(t) from the displacement sensor and the tension signal F(t) from the tension sensor, and records the stroke data and tension data.

[0019] When the displacement in the travel data exceeds a first preset threshold, and / or when the tension in the tension data exceeds a second preset threshold, the traction operation shall be stopped.

[0020] In some possible implementations

[0021] The stroke data and tension data are subjected to high-frequency noise reduction processing using moving average filtering or low-pass filtering algorithms to obtain the denoised target data.

[0022] The data points in the target data are supplemented by interpolation, and the displacement-tension relationship curve is plotted based on the supplemented target data.

[0023] In some possible implementations, the method further includes:

[0024] A displacement-tension comparison table is established based on preset calibration points, and the desired output tension value is obtained based on the comparison table and linear interpolation.

[0025] The control strategy of the wire motor is adjusted based on the desired output tension value.

[0026] In some possible implementations, extracting key parameters from the relationship curve includes:

[0027] Quantitative analysis is performed on the air travel, maximum travel, rebound force, and their fluctuations.

[0028] The idle travel is the ineffective movement distance of the brake pedal before the cable motor begins to apply effective tension. By analyzing the displacement data collected by the displacement sensor and the tension data collected by the tension sensor, the displacement value corresponding to the start of a significant increase in tension is determined.

[0029] The maximum effective stroke is the maximum distance moved from the end of the empty stroke to when the brake pedal is fully depressed. By continuously pulling the brake pedal until the displacement reaches a preset threshold or the pulling force reaches the safety upper limit, the displacement change from the end of the empty stroke to the point where traction stops is recorded.

[0030] The rebound force is the reverse force exerted by the brake pedal spring system on the cable motor, which is obtained by collecting real-time data from the displacement sensor and the tension sensor during the release of the brake pedal.

[0031] The rebound force fluctuation range is the variation of rebound force under the same displacement. The standard deviation or range of multiple tensile force values ​​corresponding to the same displacement in the "displacement-tension" relationship curve is used as the quantitative result of the rebound force fluctuation range.

[0032] In some possible implementations, after acquiring the stroke data and tension data, the method further includes:

[0033] Historical calibration data is input into a vector machine, neural network, or regression model for training, and a mapping relationship between input variables and output parameters is established; the variables include displacement, time, and temperature;

[0034] The controller predicts and extracts key parameters based on the newly acquired stroke and tension data.

[0035] In some possible implementations, the method further includes:

[0036] In the step of installing the cable motor, displacement sensor, and tension sensor on the brake pedal linkage mechanism at preset positions, the preset positions are determined based on the traction pedal force range and motor winding length range of the vehicle model: for sedans and SUVs, the fixed position and anchor point of the cable motor are adjusted so that the traction pedal force is within the range of 0-300N and the motor winding length is within the range of 0-77mm; for dump trucks, heavy trucks, and tractor units, the fixed position and anchor point of the cable motor are adjusted so that the traction pedal force is within the range of 0-500N and the motor winding length is within the range of 0-100mm.

[0037] In some possible implementations, the device for measuring the brake pedal travel is one of a photoelectric displacement sensor, a Hall effect displacement sensor, a strain gauge sensor, or a laser rangefinder; the device for measuring the tension is an external tension sensor or a Wheatstone bridge circuit composed of multiple strain gauges embedded inside the pull wire motor or in the connecting structure.

[0038] In some possible implementations, the method further includes:

[0039] In the step of obtaining stroke data and tension data by pulling the brake pedal at a preset speed under the control of the controller, the data acquisition frequency of the displacement sensor and the tension sensor is not less than 100Hz, and the timestamps of the displacement signal x(t) and the tension signal F(t) are recorded synchronously to ensure the time correspondence between the stroke data and the tension data.

[0040] As described above, this invention, by introducing a joint measurement mechanism of displacement and tension sensors and combining data analysis and control optimization strategies, enables comprehensive perception of the brake pedal's motion state, including displacement changes and corresponding tension responses. By constructing a "displacement-tension" relationship curve, it quantifies and analyzes key characteristic parameters such as the pedal's free travel, maximum effective travel, rebound force, and its fluctuation range, providing a precise basis for subsequent control. Based on the collected data, key parameters such as maximum travel, free travel, and rebound force are extracted. These parameters directly reflect the pedal's actual working range and feedback characteristics. The control system can formulate a motor control strategy that more closely resembles real-world operating conditions based on these parameters, improving the consistency and controllability of the braking system's response and avoiding braking force deviations caused by misjudging the pedal position. The controller dynamically optimizes the cable motor output based on calibration results. By writing calibration data into memory and recalling it in real time, the system can automatically adjust the cable motor drive signal to match the current pedal state. This technology improves the accuracy and stability of braking response, significantly enhancing driving safety, especially in complex road conditions or emergency braking scenarios. Employing a non-intrusive installation structure design, the sensors and actuators require no modification to the original vehicle structure; only a measuring device needs to be added to the pedal linkage component, resulting in strong compatibility and convenient installation. In summary, this invention effectively solves the control error problem caused by the unclear characteristics of the brake pedal in traditional aftermarket AEBS solutions by combining scientifically sound sensor configuration, key parameter extraction, and intelligent control strategies. Attached Figure Description

[0041] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A flowchart of a static calibration method for a vehicle-mounted cable motor brake pedal based on stroke measurement, provided in an embodiment of this application;

[0043] Figure 2 This is a schematic diagram of the installation position of the draw wire motor provided in an embodiment of this application;

[0044] Figure 3 The displacement-tension relationship curve provided for the embodiments of this application. Detailed Implementation

[0045] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application as detailed in the claims.

[0046] As a core control component of the automotive braking system, the brake pedal is a crucial interface for the driver to control the vehicle's braking through mechanical or hydraulic transmission. Through its linkage with components such as the master cylinder, brake lines, and brake pads, it converts the driver's pedal force into braking force, directly impacting driving safety and braking response characteristics. With the development of the automotive industry, the structural design of the brake pedal has been continuously optimized, but its basic function has always revolved around "precisely transmitting braking intent." Especially with the rise of autonomous driving and intelligent driver assistance technologies, the brake pedal not only needs to meet the requirements of manual operation but also needs to adapt to the mechanical intervention control of the automatic braking system, becoming a vital bridge connecting manual driving and automatic braking.

[0047] Brake pedals in different car models exhibit significant differences in characteristics due to variations in design goals, vehicle structure, and braking system configuration. These differences are primarily reflected in the following aspects: First, structural parameters differ, including variations in leverage ratios and fulcrum positions, leading to variations in braking performance under the same pedal force. Second, stroke parameters differ; the maximum stroke length and the idle stroke (the ineffective movement distance before generating effective braking force) are inconsistent, with some models having an excessively high idle stroke ratio, affecting braking response speed. Third, mechanical characteristics differ; the rebound force exhibits non-linear changes and a large fluctuation range, influenced by factors such as spring stiffness and friction coefficient, resulting in significant differences in the reverse force under the same displacement. These differences give brake pedals highly individualized braking characteristics, and without targeted adaptation, braking control precision can easily decrease.

[0048] In the aftermarket for autonomous driving and intelligent driver assistance technologies, Automatic Emergency Braking Systems (AEBS) often simulate driver pedal action using a cable-driven motor, which pulls the brake pedal via a cable to achieve automatic braking. However, existing cable-driven motors mostly employ a uniform control strategy, failing to consider the characteristics of brake pedals in different vehicle models: when faced with a pedal with high rebound force, insufficient output force may lead to braking failure; when faced with a pedal with short travel, over-response may cause false braking; simultaneously, nonlinear rebound force and travel differences can cause a mismatch between the control logic and the actual pedal state, resulting in braking delays and poor system stability. Therefore, existing control strategies cannot adapt to the diverse brake pedal characteristics of different vehicle models, making it difficult to meet the braking accuracy and safety requirements of aftermarket AEBS.

[0049] In some embodiments, such as Figure 1 As shown, this application provides a static calibration method for a vehicle-mounted cable motor brake pedal based on stroke measurement, the method comprising:

[0050] Install the cable motor, displacement sensor, and tension sensor on the brake pedal linkage mechanism according to the preset positions;

[0051] Start the wire pull motor, displacement sensor, and force sensor, and initialize them;

[0052] Under the control of the controller, the cable motor pulls the brake pedal at a preset speed to obtain stroke data and tension data;

[0053] The controller plots a displacement-tension relationship curve based on the collected stroke data and tension data, and extracts key parameters from the relationship curve. The key parameters include idle stroke, maximum effective stroke, rebound force, and fluctuation range.

[0054] The key parameters are analyzed to obtain calibration results, and the calibration results are input into the automatic emergency braking system.

[0055] The automatic emergency braking system determines the control strategy for the cable motor based on the calibration results.

[0056] During the installation process, this application adapts to the traction force and winding length range of different vehicle models through preset positions, without modifying the original vehicle structure. The non-intrusive design reduces the installation difficulty and cost in the aftermarket, while being compatible with various vehicle models such as sedans, off-road vehicles, and trucks, thus improving the versatility of the solution.

[0057] Based on the scientific analysis of the "displacement-tension" relationship curve, this application provides a quantitative control basis for the Automatic Emergency Braking System (AEBS), enabling the output force and response time of the cable motor to be dynamically matched with the actual characteristics of the brake pedal, reducing braking delay, false triggering, and other situations, and significantly improving the system control accuracy and operational stability.

[0058] By quantitatively extracting key parameters such as idle travel, maximum effective travel, rebound force, and fluctuation range, this technology overcomes the limitations of existing technologies that rely on experience-based judgment or simple measurement and cannot adapt to the differences in brake pedal characteristics (structure, travel, rebound force, etc.) of different vehicle models. This allows the calibration results to accurately match different vehicle models and avoids problems such as inappropriate force and response deviation caused by a uniform control strategy.

[0059] By analyzing and calibrating key parameters, the control strategy of the cable motor can be specifically adapted to the characteristics of different vehicle models, such as free travel and rebound force, to shorten the response time of effective braking, ensure the consistency of braking action with actual needs, and enhance driving safety in emergency braking scenarios.

[0060] In some embodiments, the method includes:

[0061] After starting the cable motor, displacement sensor, and tension sensor and initializing, the traction speed and direction are determined according to the vehicle model and calibration requirements;

[0062] The controller starts the cable motor to perform traction operation based on the traction speed and direction, and records the time.

[0063] When the stopping conditions are met, the traction operation is stopped.

[0064] In some embodiments, the method further includes:

[0065] When the controller starts the cable motor to perform traction operation based on the traction speed and direction, it collects the displacement signal x(t) from the displacement sensor and the tension signal F(t) from the tension sensor, and records the stroke data and tension data.

[0066] When the displacement in the travel data exceeds a first preset threshold, and / or when the tension in the tension data exceeds a second preset threshold, the traction operation shall be stopped.

[0067] By installing the cable motor, displacement sensor, and force sensor (built into the motor) on the brake pedal linkage mechanism in preset positions, it is ensured that each sensor can accurately reflect the displacement changes and force state of the pedal. Different vehicle models have different brake pedal travel, and different vehicle models have different traction forces on the brake pedal. Furthermore, the fixed position of the cable motor varies, the force required to pull the motor to traction the brake pedal also varies, and the length of cable required for the cable motor to traction the brake pedal also varies.

[0068] In some embodiments, the method further includes:

[0069] In the step of installing the cable motor, displacement sensor, and tension sensor on the brake pedal linkage mechanism at preset positions, the preset positions are determined based on the traction pedal force range and motor winding length range of the vehicle model: for sedans and SUVs, the fixed position and anchor point of the cable motor are adjusted so that the traction pedal force is within the range of 0-300N and the motor winding length is within the range of 0-77mm; for dump trucks, heavy trucks, and tractor units, the fixed position and anchor point of the cable motor are adjusted so that the traction pedal force is within the range of 0-500N and the motor winding length is within the range of 0-100mm.

[0070] During the installation of the cable-operated motor, based on Table 1 and considering different vehicle models and the winding length range of the cable-operated motor, the fixing position of the cable-operated motor and the position of the cable anchor point should be adjusted appropriately. Figure 2 As shown.

[0071] Table 1

[0072]

[0073]

[0074] After system startup, the controller first performs an initialization step, configuring and monitoring the status of the cable motor, displacement sensor, and tension sensor. This step ensures all hardware modules are in normal working order and establishes a stable communication link, laying the foundation for subsequent data acquisition and control operations. After initialization, the system enters the parameter setting phase, where the user or control system sets the traction speed and direction according to the vehicle model and calibration requirements. For example, the traction speed can be set to a constant value vpull (unit: mm / s), and the direction can be selected as forward or reverse traction depending on the installation location to accommodate brake pedal systems with different structural layouts. Subsequently, the controller starts the cable motor to begin the traction operation and records the start timestamp t0. During this process, the system continuously acquires the displacement signal x(t) from the displacement sensor and the tension signal F(t) from the tension sensor, with a sampling frequency of no less than 100Hz to ensure the data's time resolution meets the analysis requirements. The traction process will continue until any of the following stopping conditions are met:

[0075] The displacement reaches the first preset threshold x(t) ≥ xmax;

[0076] The tensile force reaches the second preset threshold (i.e., the safety upper limit) F(t) ≥ Fthreshold;

[0077] Once any of the above conditions are triggered, the system will immediately stop the operation of the wire-pulling motor.

[0078] In some embodiments, the method further includes:

[0079] The stroke data and tension data are subjected to high-frequency noise reduction processing using moving average filtering or low-pass filtering algorithms to obtain the denoised target data.

[0080] The data points in the target data are supplemented by interpolation, and the displacement-tension relationship curve is plotted based on the supplemented target data.

[0081] The system stops the wire-drawing motor and caches the collected raw data in a memory buffer. To improve data quality, the system further filters this raw data, using algorithms such as moving average filtering or low-pass filtering to remove high-frequency noise interference. Then, interpolation is used to supplement the data points, forming a more refined dataset. Figure 3 The continuous, smooth displacement-tension curve shown:

[0082] Finterp(x) = interpolation function(F(t), x(t));

[0083] Finterp(x) represents the tensile force value at displacement x, which is used to construct a complete mechanical response model.

[0084] The displacement values ​​are sorted in ascending order to ensure that the displacement data shows a monotonically increasing trend (because the displacement of the brake pedal continues to increase during the traction process of the cable motor), eliminating the disorder of displacement values ​​caused by random fluctuations in the time series, and providing an ordered data foundation for curve plotting.

[0085] For the sorted displacement sequence {x1,x2,...,x} n The tensile force value corresponding to each displacement point is determined by interpolation operations (such as linear interpolation, cubic spline interpolation, etc.): for two adjacent known displacement points x i With x i+1 If there exists an intermediate displacement x(x) that was not directly collected i <x<x i+1 Then, the tensile force F(x) corresponding to the displacement is calculated according to the interpolation function Finterp(x), so that the discrete data pairs {(x1,F1),(x2,F2),...,(x)} form a one-to-one mapping between displacement and tensile force. n ,F n )}.

[0086] The discrete data above is used to fit the input curve model, and a continuous function curve F(x) is constructed using the least squares method or a polynomial fitting algorithm, where the independent variable is displacement x and the dependent variable is tension F. During the fitting process, the fitting order needs to be controlled (e.g., a third-order polynomial) to avoid overfitting, ensuring that the curve accurately reflects the nonlinear relationship between displacement and tension (e.g., the nonlinear characteristics of rebound force). Simultaneously, smoothing is used to eliminate any minor fluctuations that may remain after interpolation, making the curve continuous and without significant abrupt changes.

[0087] Calculate the goodness of fit (e.g., R²) between the fitted curve and the supplemented target data. 2 (value), when R 2 When the value is greater than or equal to a preset threshold (e.g., 0.9), the curve is considered valid and can accurately represent the relationship between the displacement and tension of the brake pedal during traction. If the goodness of fit is not up to standard, the interpolation process is repeated or the filtering parameters are adjusted until the curve meets the accuracy requirements.

[0088] In some embodiments, the method further includes:

[0089] A displacement-tension comparison table is established based on preset calibration points, and the desired output tension value is obtained based on the comparison table and linear interpolation.

[0090] The control strategy of the wire motor is adjusted based on the desired output tension value.

[0091] This invention employs a lookup table method combined with interpolation as the primary control strategy. A "displacement-tension" lookup table is established based on preset calibration points. During actual control, the desired output tension value is quickly obtained through table lookup and linear interpolation, thereby driving the cable-stayed motor. This method is simple to implement, responds rapidly, and is suitable for vehicle-mounted control scenarios with high real-time requirements. Alternatively, advanced control algorithms such as PID feedback control or fuzzy control can also be used. PID control continuously adjusts the output to minimize the error between the setpoint and the actual value, achieving high-precision dynamic adjustment; fuzzy control is suitable for nonlinear systems with high uncertainty, and can more flexibly cope with complex operating condition changes.

[0092] In some embodiments, extracting key parameters from the relationship curve includes:

[0093] Quantitative analysis is performed on the air travel, maximum travel, rebound force, and their fluctuations.

[0094] The idle travel is the ineffective movement distance of the brake pedal before the cable motor begins to apply effective tension. By analyzing the displacement data collected by the displacement sensor and the tension data collected by the tension sensor, the displacement value corresponding to the start of a significant increase in tension is determined.

[0095] The maximum effective stroke is the maximum distance moved from the end of the empty stroke to when the brake pedal is fully depressed. By continuously pulling the brake pedal until the displacement reaches a preset threshold or the pulling force reaches the safety upper limit, the displacement change from the end of the empty stroke to the point where traction stops is recorded.

[0096] The rebound force is the reverse force exerted by the brake pedal spring system on the cable motor, which is obtained by collecting real-time data from the displacement sensor and the tension sensor during the release of the brake pedal.

[0097] The rebound force fluctuation range is the variation of rebound force under the same displacement. The standard deviation or range of multiple tensile force values ​​corresponding to the same displacement in the "displacement-tension" relationship curve is used as the quantitative result of the rebound force fluctuation range.

[0098] During the data analysis phase, the system extracts several key parameters from the interpolated curve, including but not limited to:

[0099] Maximum effective stroke xeff: refers to the maximum displacement from the initial position until the tension increases significantly;

[0100] The idle travel xdead represents the invalid travel distance before the wire motor begins to apply effective tension;

[0101] Rebound force curve: describes the trend of tension change during displacement recovery when the pedal is released, and can be used to evaluate the friction characteristics of the system;

[0102] Tension fluctuation range ΔF: used to measure system stability.

[0103] The calibration process is as follows:

[0104] 1. No-travel calibration (xdead)

[0105] Data preprocessing: On the displacement-tension curve, extract the displacement interval [x0, x1] before the tension value first exceeds the reference threshold (e.g., 0.5N).

[0106] Inflection point identification: Calculate the rate of change of tension (ΔF / Δx) within the interval. When the rate of change exceeds the set gradient threshold (e.g., 0.2 N / mm) for three consecutive sampling points, the corresponding displacement value x1 is the end point of the empty stroke.

[0107] Result verification: The test was repeated 3 times, and the average value was taken as the final no-travel calibration value. The error range was controlled within [value missing].

[0108] Within ±0.5mm.

[0109] 2. Maximum effective travel calibration (xeff)

[0110] Trip termination judgment: When the displacement reaches the preset safety threshold (e.g., 77mm for cars, 100mm for trucks) or the pulling force reaches the mechanical limit (e.g., 300N), stop traction and record the displacement value xmax at this time.

[0111] Effective travel calculation: Maximum effective travel xeff = xmax - xdead, where xdead is the empty travel calibration value.

[0112] Redundancy check: The pressure build-up of the braking system is detected by a pressure sensor to ensure that the pressure value corresponding to xeff reaches more than 95% of the system working pressure.

[0113] 3. Rebound force characteristic calibration

[0114] Release curve acquisition: Control the pull wire motor to release the pedal at a constant speed (e.g., 5mm / s), and synchronously record the displacement-tension data to form the rebound force curve Frelease(x) of the release stage.

[0115] Feature point extraction:

[0116] Initial rebound force: The tension value F0 when the pedal begins to be released.

[0117] Peak rebound force: The maximum tensile force Fpeak during the release process.

[0118] Equilibrium position: The displacement value x when the rebound force first drops to 0.

[0119] 4. Rebound force fluctuation range calibration (ΔF)

[0120] Window sliding calculation: Slide a fixed window (e.g., 5mm) on the displacement-tension curve and calculate the standard deviation σ(F) of the tension in each window.

[0121] Fluctuation feature extraction:

[0122] Maximum fluctuation value: The maximum value of σ(F) in all windows, σmax.

[0123] Fluctuation range: Record the displacement range where σ(F) exceeds the threshold (e.g., 0.3N).

[0124] Stability assessment: Calculate the fluctuation coefficient K = σmax / Favg, where Favg is the average tension over the entire process. The smaller the K value, the higher the system stability.

[0125] Input the calibration results into the simulation model, compare the actual braking effect with the expected parameters, and adjust the calibration parameters until the error is less than 5%.

[0126] In some embodiments, after acquiring the stroke data and tension data, the method further includes:

[0127] Historical calibration data is input into a vector machine, neural network, or regression model for training, and a mapping relationship between input variables and output parameters is established; the variables include displacement, time, and temperature;

[0128] The controller predicts and extracts key parameters based on the newly acquired stroke and tension data.

[0129] A machine learning-based fitting model, such as a support vector machine (SVM), neural network (NN), or regression model, is used to train a large amount of historical calibration data to establish a mapping relationship between input variables (such as displacement, time, and temperature) and output parameters. In actual operation, the system can automatically predict and extract relevant parameters based on newly collected data, improving the system's adaptability and intelligence level.

[0130] The system writes the extracted key parameters as calibration results into the non-volatile memory of the AEBS (Automatic Emergency Braking System) or the vehicle controller to optimize the control strategy of the cable motor. For example, in actual control, the motor output force Fmotor can be dynamically adjusted based on the calibration results to better match the actual pedal feedback characteristics.

[0131] Fmotor=kp×(xtarget–xcurrent)+Foffset;

[0132] Where kp is the proportional coefficient, xtarget is the target displacement, xcurrent is the current displacement, and Foffset is the offset tension value obtained from calibration. After the data writing is completed, the system displays the calibration completion status through the human-machine interface, prompting the user that the calibration operation has been successfully completed. The entire software process realizes high-precision perception of the brake pedal characteristics by the cable motor and adaptive optimization of dynamic control parameters, improving the response speed of the aftermarket AEBS cable motor traction brake pedal.

[0133] In some embodiments, the device for measuring the brake pedal travel is one of a photoelectric displacement sensor, a Hall effect displacement sensor, a strain gauge sensor, or a laser rangefinder; the device for measuring tension is an external tension sensor or a Wheatstone bridge circuit composed of multiple strain gauges embedded inside the pull wire motor or in the connecting structure.

[0134] Displacement measurement methods employ photoelectric, Hall effect, or encoder displacement sensors to measure the brake pedal travel in real time, obtaining a high-precision displacement signal x(t) for subsequent data processing and control strategy generation. This method offers advantages such as mature structure, fast response, and high stability, making it the preferred implementation method. Alternatively, strain gauge sensors or laser ranging devices can also be used to achieve displacement measurement. Strain gauge sensors, attached to the surface of an elastic element, sense its deformation, thus indirectly reflecting displacement changes; while laser ranging utilizes non-contact optical principles, making it suitable for applications with limited installation space or where mechanical interference must be avoided.

[0135] The tension measurement method uses an external tension sensor, directly connected in series between the cable motor and the brake pedal, to collect the tension value F(t) applied during traction. This method has the advantages of intuitive measurement, high accuracy, and easy integration. As an alternative, a built-in strain gauge bridge circuit can be used. This involves embedding a Wheatstone bridge circuit composed of multiple strain gauges inside the cable motor or in the connecting structure. By detecting the resistance change caused by structural deformation, the corresponding force is calculated. This method eliminates the need for additional external sensors, which is beneficial for system miniaturization and lightweight design, and also offers advantages in cost control.

[0136] In some embodiments, the method further includes:

[0137] In the step of obtaining stroke data and tension data by pulling the brake pedal at a preset speed under the control of the controller, the data acquisition frequency of the displacement sensor and the tension sensor is not less than 100Hz, and the timestamps of the displacement signal x(t) and the tension signal F(t) are recorded synchronously to ensure the time correspondence between the stroke data and the tension data.

[0138] A sampling frequency of 100Hz or higher can record the displacement changes and force response of the brake pedal at high frequencies, accurately capturing subtle features in key stages such as nonlinear fluctuations in rebound force and the transition from idle travel to effective travel. This avoids the loss of critical data due to excessively large sampling intervals, ensuring that the "displacement-force" relationship curve fully reflects the dynamic characteristics of the pedal. Synchronous recording of timestamps strictly guarantees the time correspondence between the displacement signal x(t) and the force signal F(t), eliminating deviations in their acquisition timing. This allows the plotted "displacement-force" relationship curve to accurately map the pedal state at the same moment, providing accurate spatiotemporal correlation data for subsequent extraction of key parameters such as idle travel and maximum effective travel, avoiding parameter calculation errors caused by data misalignment.

[0139] High-frequency data acquisition and time synchronization ensure high data density and consistency, making quantitative analysis of fine parameters such as rebound force fluctuation range and effective stroke boundary more reliable. For example, the critical point of "significant increase" in tensile force (end of empty stroke) can be accurately identified by subtle changes in adjacent data points, avoiding boundary judgment deviations caused by data sparsity or asynchrony.

[0140] As described in the above embodiments, this application provides a static calibration method for vehicle-mounted cable motor brake pedals based on stroke measurement. By introducing a joint measurement mechanism of displacement and tension sensors, and combining data analysis and control optimization strategies, it can achieve comprehensive perception of the brake pedal's motion state, including displacement changes and corresponding tension responses. By constructing a "displacement-tension" relationship curve, it can quantitatively analyze key characteristic parameters such as the pedal's idle travel, maximum effective travel, rebound force, and its fluctuation range, providing accurate basis for subsequent control. Based on the collected data, key parameters such as maximum travel, idle travel, and rebound force are extracted. These parameters directly reflect the actual working range and feedback characteristics of the pedal. The control system can formulate a motor control strategy that more closely resembles real-world operating conditions based on these parameters, improving the consistency and controllability of the braking system's response and avoiding braking force deviations caused by misjudging the pedal position. The controller dynamically optimizes the cable motor output based on the calibration results. By writing the calibration data into the memory and recalling it in real time, the system can automatically adjust the cable motor drive signal to match the current pedal state. This technology improves the accuracy and stability of braking response, especially in complex road conditions or emergency braking scenarios, significantly enhancing driving safety. Employing a non-intrusive installation structure design, the sensors and actuators require no modification to the original vehicle structure; only a measuring device needs to be added to the pedal linkage component, resulting in strong compatibility and convenient installation. In summary, this invention effectively solves the control error problem caused by the unclear characteristics of the brake pedal in traditional aftermarket AEBS solutions by combining scientifically sound sensor configuration, key parameter extraction, and intelligent control strategies.

[0141] Similar parts between the embodiments provided in this application can be referred to mutually. The specific implementation methods provided above are only a few examples under the overall concept of this application and do not constitute a limitation on the scope of protection of this application. For those skilled in the art, any other implementation methods extended from the solution of this application without creative effort shall fall within the scope of protection of this application.

Claims

1. A static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement, characterized in that, The method includes: Install the cable motor, displacement sensor, and tension sensor on the brake pedal linkage mechanism according to the preset positions; Start the wire pull motor, displacement sensor, and force sensor, and initialize them; Under the control of the controller, the cable motor pulls the brake pedal at a preset speed to obtain stroke data and tension data; The controller plots a displacement-tension relationship curve based on the collected stroke data and tension data, and extracts key parameters from the relationship curve. The key parameters include idle stroke, maximum effective stroke, rebound force, and fluctuation range. The key parameters are analyzed to obtain calibration results, and the calibration results are input into the automatic emergency braking system. The automatic emergency braking system determines the control strategy for the cable motor based on the calibration results; The method further includes: The stroke data and tension data are subjected to high-frequency noise reduction processing using moving average filtering or low-pass filtering algorithms to obtain the denoised target data. The data points in the target data are supplemented by interpolation, and the displacement-tension relationship curve is plotted based on the supplemented target data; A displacement-tension comparison table is established based on preset calibration points, and the desired output tension value is obtained based on the comparison table and linear interpolation. The control strategy of the wire motor is adjusted based on the desired output tension value.

2. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that, The method includes: After starting the cable motor, displacement sensor, and tension sensor and initializing, the traction speed and direction are determined according to the vehicle model and calibration requirements; The controller starts the cable motor to perform traction operation based on the traction speed and direction, and records the time. When the stopping conditions are met, the traction operation is stopped.

3. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 2, characterized in that, The method further includes: When the controller starts the cable motor to perform traction operation based on the traction speed and direction, the displacement signal from the displacement sensor is collected. x(t) and the tension signal from the tension sensor F(t) And record travel data and tension data; When the displacement in the travel data exceeds a first preset threshold, and / or when the tension in the tension data exceeds a second preset threshold, the traction operation shall be stopped.

4. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that, Extracting key parameters from the relationship curve includes: Quantitative analysis is performed on the air travel, maximum travel, rebound force, and their fluctuations. The idle travel is the ineffective movement distance of the brake pedal before the cable motor begins to apply effective tension. By analyzing the displacement data collected by the displacement sensor and the tension data collected by the tension sensor, the displacement value corresponding to the start of a significant increase in tension is determined. The maximum effective stroke is the maximum distance moved from the end of the empty stroke to when the brake pedal is fully depressed. By continuously pulling the brake pedal until the displacement reaches a preset threshold or the pulling force reaches the safety limit, the displacement change from the end of the empty stroke to the point where traction stops is recorded. The rebound force is the reverse force exerted by the brake pedal spring system on the cable motor, which is obtained by collecting real-time data from the displacement sensor and the tension sensor during the release of the brake pedal. The rebound force fluctuation range is the variation of rebound force under the same displacement. The standard deviation or range of multiple tensile force values ​​corresponding to the same displacement in the "displacement-tension" relationship curve is used as the quantitative result of the rebound force fluctuation range.

5. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that, After acquiring the stroke data and tension data, the method further includes: Historical calibration data is input into a vector machine, neural network, or regression model for training, and a mapping relationship between input variables and output parameters is established; the variables include displacement, time, and temperature; The controller predicts and extracts key parameters based on the newly acquired stroke and tension data.

6. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that, The method further includes: In the step of installing the cable motor, displacement sensor, and tension sensor on the brake pedal linkage mechanism at preset positions, the preset positions are determined based on the traction pedal force range and motor winding length range of the vehicle model: for sedans and SUVs, the fixed position and anchor point of the cable motor are adjusted so that the traction pedal force is within the range of 0~300N and the motor winding length is within the range of 0~77mm; for dump trucks, heavy trucks, and tractors, the fixed position and anchor point of the cable motor are adjusted so that the traction pedal force is within the range of 0~500N and the motor winding length is within the range of 0~100mm.

7. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that, The device used to measure the brake pedal travel is one of the following: photoelectric displacement sensor, Hall effect displacement sensor, strain gauge sensor, or laser rangefinder; the device used to measure tension is an external tension sensor or a Wheatstone bridge circuit composed of multiple strain gauges embedded inside the pull wire motor or in the connecting structure.

8. The static calibration method for vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that, The method further includes: In the step of acquiring stroke and tension data by pulling the brake pedal at a preset speed under the control of the controller, the data acquisition frequency of the displacement sensor and the tension sensor is not less than 100Hz, and the displacement signal is recorded synchronously. x(t) With tension signal F(t) The timestamp is used to ensure the time correspondence between the travel data and the tension data.

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