Vehicle-mounted stay wire motor brake pedal static calibration method based on stroke measurement

Abstract

The invention provides a static calibration method for a vehicle-mounted stay wire motor brake pedal based on stroke measurement, which can realize comprehensive perception of the motion state of the brake pedal by introducing a joint measurement mechanism of a displacement sensor and a tension sensor and combining data analysis and a control optimization strategy, and can realize static calibration of the brake pedal by constructing a displacement-tension relation curve. Key parameters such as the maximum stroke, the idle stroke and the resilience force are extracted based on collected data, a motor control strategy closer to the real working condition is formulated, the response consistency and controllability of a braking system are improved, and braking force deviation caused by misjudgment of the pedal position is avoided. According to the technical content, the accuracy and stability of braking response are improved, and the driving safety is remarkably enhanced especially under complex road conditions or emergency braking scenes. Through a mode of combining sensor configuration, key parameter extraction and an intelligent control strategy, the problem of control errors caused by undefined characteristics of a brake pedal in a traditional AEBS after-loading scheme is effectively solved.

Description

Technical Field

[0001] The present 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 stroke measurement. Background Art

[0002] As the core control component of a vehicle's braking system, the brake pedal is the key interface through which the driver controls the vehicle's braking via mechanical or hydraulic transmission. Working in conjunction with components such as the vehicle's master cylinder, brake lines, and brake pads, it converts the driver's pedaling force into vehicle braking force, directly impacting driving safety and braking response. While the structural design of the brake pedal has been continuously optimized with the development of the automotive industry, its fundamental function has always revolved around "precisely transmitting braking intent." Especially with the rise of autonomous driving and intelligent assisted driving technologies, the brake pedal must not only meet the needs of manual control but also adapt to the mechanical intervention control of the automatic braking system, becoming a crucial bridge between manual driving and automatic braking.

[0003] Due to differences in design objectives, vehicle body structure, and brake system configuration, brake pedals on different vehicle models exhibit significant differences in characteristics. These differences are primarily reflected in the following aspects: First, structural parameters vary, including differences in mechanical properties such as leverage ratio and fulcrum position, which lead to deviations in braking effect under the same pedaling force; second, stroke parameters vary, with the maximum stroke length and idle stroke (the ineffective movement distance before effective braking force is generated) inconsistent. In some models, the idle stroke ratio is too high, affecting braking response speed; third, mechanical properties vary, with rebound force exhibiting nonlinear changes and a wide range of fluctuations. Influenced by factors such as spring stiffness and friction coefficient, the reaction force under the same displacement varies significantly. These differences make the braking characteristics of brake pedals highly personalized. Without targeted adaptation, braking control accuracy can be reduced.

[0004] In the aftermarket for autonomous driving and intelligent assisted driving technologies, automatic emergency braking systems (AEBS) often use a cable motor device to simulate the driver's pedaling action, pulling the cable to pull the brake pedal to achieve automatic braking. However, existing cable motors often use a unified control strategy that does not consider the differences in brake pedal characteristics of different vehicle models: when faced with a pedal with high rebound force, insufficient output force may cause braking failure; when faced with a pedal with a short idle travel, excessive response may cause false braking. At the same time, nonlinear rebound force and travel differences can cause a mismatch between the control logic and the actual pedal state, resulting in braking delays, poor system stability, and other problems. Therefore, existing control strategies are unable to adapt to the diverse brake pedal characteristics of different vehicle models and struggle to meet the braking accuracy and safety requirements of aftermarket AEBS. Summary of the Invention

[0005] The present application provides a static calibration method for a vehicle-mounted cable-operated motor brake pedal based on stroke measurement, in order to solve the problem that existing control strategies cannot adapt to the brake pedal characteristics of various vehicle models and are difficult to meet the requirements of after-installed AEBS for braking accuracy and safety.

[0006] The present application provides a static calibration method for a vehicle-mounted cable-operated motor brake pedal based on stroke 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 pulling motor, displacement sensor and tension sensor and initialize them;

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

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

[0011] Analyzing the key parameters to obtain calibration results, and inputting the calibration results into an automatic emergency braking system;

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

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

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

[0015] The controller starts the wire pulling motor to perform a pulling operation based on the pulling speed and direction, and records the time;

[0016] When the stop condition is satisfied, the pulling operation is stopped.

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

[0018] When the controller starts the wire pulling motor to perform a pulling operation based on the pulling speed and direction, a displacement signal x(t) of the displacement sensor and a tension signal F(t) of the tension sensor are collected, and travel data and tension data are recorded;

[0019] When the displacement in the travel data is greater than a first preset threshold, and / or when the pulling force in the pulling force data is greater than a second preset threshold, the pulling operation is stopped.

[0020] In some possible implementations,

[0021] Performing high-frequency noise reduction processing on the travel data and the tension data using a sliding average filter or a low-pass filter algorithm to obtain denoised target data;

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

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

[0024] Establishing a displacement-tension comparison table according to preset calibration points, and obtaining the expected output tension value according to the comparison table and linear interpolation;

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

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

[0027] Obtain quantitative analysis of empty stroke, maximum stroke, rebound force and their fluctuations;

[0028] The idle stroke is the ineffective movement distance of the brake pedal before the cable motor starts to apply effective tension. The displacement data collected by the displacement sensor and the tension data collected by the tension sensor are analyzed to determine the displacement value corresponding to the time when the tension begins to increase significantly.

[0029] The maximum effective stroke is the maximum distance traveled from the end of the idle stroke to when the brake pedal is fully depressed. The brake pedal is continuously pulled until the displacement reaches a preset threshold or the pulling force reaches a safety upper limit, and the displacement change from the end of the idle stroke to the time when the pulling 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 amplitude of the rebound force change under the same displacement. The standard deviation or range of multiple tension values ​​corresponding to the same displacement in the "displacement-tension" relationship curve is calculated as the quantitative result of the rebound force fluctuation range.

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

[0033] Input historical calibration data to the vector machine, neural network or regression model for training, and establish a mapping relationship between input variables and output parameters; the variables include displacement, time, and temperature;

[0034] The controller predicts and extracts key parameters based on the newly collected travel data 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 according to a preset position, the preset position is determined according to the traction pedal force range and the motor winding length range of the vehicle model: for cars and off-road vehicles, adjust the fixed position and anchor point of the cable motor so that the traction pedal force is within the range of 0 to 300N and the motor winding length is within the range of 0 to 77mm; for dump trucks, large trucks and tractors, adjust the fixed position and anchor point of the cable motor so that the traction pedal force is within the range of 0 to 500N and the motor winding length is within the range of 0 to 100mm.

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

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

[0039] Under the control of the controller, the wire motor pulls the brake pedal at a preset speed to obtain travel data and tension data. The data acquisition frequency of the displacement sensor and the tension sensor is not less than 100 Hz, 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 travel data and the tension data.

[0040] As can be seen from the above, the present invention, by introducing a combined measurement mechanism of displacement sensors and tension sensors, combined with data analysis and control optimization strategies, 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, key characteristic parameters such as the pedal's idle travel, maximum effective travel, rebound force, and its fluctuation range can be quantitatively analyzed, providing a precise basis for subsequent control. Key parameters such as maximum travel, idle travel, and rebound force are extracted based on collected data. These parameters directly reflect the pedal's actual operating range and feedback characteristics. Based on these parameters, the control system can formulate a motor control strategy that is more closely aligned with real-world operating conditions, improving the response consistency and controllability of the brake system and avoiding braking force deviations caused by misjudgment of pedal position. The controller dynamically optimizes the cable motor output based on the calibration results. By writing the calibration data to memory and accessing 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, particularly in complex road conditions or emergency braking scenarios. The non-invasive mounting structure design eliminates the need to modify the original vehicle structure for the sensor and actuator; only the measurement device needs to be installed on the pedal linkage component, resulting in strong compatibility and convenient installation. In summary, this invention effectively addresses the control error problem caused by the unclear brake pedal characteristics in traditional aftermarket AEBS solutions by combining scientific and rational sensor configuration, key parameter extraction, and intelligent control strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0042] Figure 1 A flow chart of a static calibration method for a vehicle-mounted cable-operated motor brake pedal based on stroke measurement provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of the installation position of the wire-pulling motor provided in an embodiment of the present application;

[0044] Figure 3 This is a displacement-tension relationship curve provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The following embodiments are described in detail, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numbers in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following embodiments are not intended to represent all possible implementations consistent with the present application. They are merely examples of systems and methods consistent with certain aspects of the present application, as detailed in the claims.

[0046] As the core control component of a vehicle's braking system, the brake pedal is the key interface through which the driver controls the vehicle's braking via mechanical or hydraulic transmission. Working in conjunction with components such as the vehicle's master cylinder, brake lines, and brake pads, it converts the driver's pedaling force into vehicle braking force, directly impacting driving safety and braking response. While the structural design of the brake pedal has been continuously optimized with the development of the automotive industry, its fundamental function has always revolved around "precisely transmitting braking intent." Especially with the rise of autonomous driving and intelligent assisted driving technologies, the brake pedal must not only meet the needs of manual control but also adapt to the mechanical intervention control of the automatic braking system, becoming a crucial bridge between manual driving and automatic braking.

[0047] Due to differences in design objectives, vehicle body structure, and brake system configuration, brake pedals on different vehicle models exhibit significant differences in characteristics. These differences are primarily reflected in the following aspects: First, structural parameters vary, including differences in mechanical properties such as leverage ratio and fulcrum position, which lead to deviations in braking effect under the same pedaling force; second, stroke parameters vary, with the maximum stroke length and idle stroke (the ineffective movement distance before effective braking force is generated) inconsistent. In some models, the idle stroke ratio is too high, affecting braking response speed; third, mechanical properties vary, with rebound force exhibiting nonlinear changes and a wide range of fluctuations. Influenced by factors such as spring stiffness and friction coefficient, the reaction force under the same displacement varies significantly. These differences make the braking characteristics of brake pedals highly personalized. Without targeted adaptation, braking control accuracy can be reduced.

[0048] In the aftermarket for autonomous driving and intelligent assisted driving technologies, automatic emergency braking systems (AEBS) often use a cable motor device to simulate the driver's pedaling action, pulling the cable to pull the brake pedal to achieve automatic braking. However, existing cable motors often use a unified control strategy that does not consider the differences in brake pedal characteristics of different vehicle models: when faced with a pedal with high rebound force, insufficient output force may cause braking failure; when faced with a pedal with a short idle travel, excessive response may cause false braking. At the same time, nonlinear rebound force and travel differences can cause a mismatch between the control logic and the actual pedal state, resulting in braking delays, poor system stability, and other problems. Therefore, existing control strategies are unable to adapt to the diverse brake pedal characteristics of different vehicle models and struggle to meet the braking accuracy and safety requirements of aftermarket AEBS.

[0049] In some embodiments, Figure 1 As shown, the present 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 pulling motor, displacement sensor and tension sensor and initialize them;

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

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

[0054] Analyzing the key parameters to obtain calibration results, and inputting the calibration results into an automatic emergency braking system;

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

[0056] During the installation process of this application, the traction force and winding length range of different models are adapted through preset positions without changing the original vehicle structure. The non-invasive design reduces the installation difficulty and cost in the aftermarket. At the same time, it is adaptable to a variety of models such as sedans, SUVs, and trucks, thereby 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), so that the output force and response time of the cable motor can be dynamically matched with the actual characteristics of the brake pedal, reducing braking delays, false triggering, etc., and significantly improving the system control accuracy and operation stability.

[0058] By quantitatively extracting key parameters such as idle stroke, maximum effective stroke, rebound force and fluctuation range, the system breaks through the limitations of existing technologies that rely on experience-based judgment or simple measurement and are unable to adapt to the differences in brake pedal characteristics (structure, stroke, rebound force, etc.) of different models. The calibration results can be accurately matched to different models, avoiding problems such as improper force and response deviation caused by unified control strategies.

[0059] Through the analysis and calibration of key parameters, the control strategy of the cable motor can be specifically adapted to the idle travel, rebound force and other characteristics of different vehicle models, shortening the response time of effective braking, ensuring the consistency of braking action with actual needs, and enhancing 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 them, the pulling speed and direction are determined according to the vehicle model and calibration requirements;

[0062] The controller starts the wire pulling motor to perform a pulling operation based on the pulling speed and direction, and records the time;

[0063] When the stop condition is satisfied, the pulling operation is stopped.

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

[0065] When the controller starts the wire pulling motor to perform a pulling operation based on the pulling speed and direction, a displacement signal x(t) of the displacement sensor and a tension signal F(t) of the tension sensor are collected, and travel data and tension data are recorded;

[0066] When the displacement in the travel data is greater than a first preset threshold, and / or when the pulling force in the pulling force data is greater than a second preset threshold, the pulling operation is stopped.

[0067] By installing the cable motor, displacement sensor, and tension sensor (built into the motor) in the brake pedal linkage mechanism according to preset positions, each sensor can accurately reflect the displacement changes and force status of the pedal. Different car models have different brake pedal travels, and the force required to pull the brake pedal varies. Also, the cable motor's fixed position varies, and the force required to pull the brake pedal varies, resulting in different wire lengths required to pull the brake pedal.

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

[0069] In the step of installing the cable motor, displacement sensor and tension sensor on the brake pedal linkage mechanism according to a preset position, the preset position is determined according to the traction pedal force range and the motor winding length range of the vehicle model: for cars and off-road vehicles, adjust the fixed position and anchor point of the cable motor so that the traction pedal force is within the range of 0 to 300N and the motor winding length is within the range of 0 to 77mm; for dump trucks, large trucks and tractors, adjust the fixed position and anchor point of the cable motor so that the traction pedal force is within the range of 0 to 500N and the motor winding length is within the range of 0 to 100mm.

[0070] During the installation of the cable motor, based on Table 1 and according to the different vehicle models and the winding length range of the cable motor, the fixed position of the cable motor and the position of the cable anchor point are appropriately adjusted as follows: Figure 2 shown.

[0071] Table 1

[0072]

[0073]

[0074] After the system is started, the controller first performs the initialization step to configure and check the status of the wire pulling motor, displacement sensor and tension sensor. This step ensures that all hardware modules are in normal working condition and establishes a stable communication link, laying the foundation for subsequent data acquisition and control operations. After the initialization is completed, the system enters the parameter setting stage, and the user or the control system will set 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 according to the installation position to adapt to brake pedal systems with different structural layouts. Subsequently, the controller starts the wire pulling motor to start the traction operation and records the starting timestamp t0. During this process, the system continuously collects the displacement signal x(t) from the displacement sensor and the tension signal F(t) from the tension sensor, with a sampling frequency of not less than 100Hz to ensure that the time resolution of the data meets the analysis requirements. The traction process will continue until any of the following stop conditions is met:

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

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

[0077] Once one of the above conditions is triggered, the system immediately stops the wire pulling motor.

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

[0079] Performing high-frequency noise reduction processing on the travel data and the tension data using a sliding average filter or a low-pass filter algorithm to obtain denoised target data;

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

[0081] When the wire pulling motor stops working, the collected raw data is cached in the memory buffer. In order to improve the data quality, the system further filters these raw data, such as using sliding average filtering or low-pass filtering algorithms to remove high-frequency noise interference; then, the data points are supplemented by interpolation operations to form Figure 3 The continuous and smooth "displacement-tension" curve shown:

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

[0083] Among them, Finterp(x) represents the tensile force value corresponding to the 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 presents a monotonically increasing trend (because the brake pedal displacement continues to increase during the traction process of the cable motor), eliminating the disordered displacement values ​​caused by possible accidental fluctuations in the time series, and providing an ordered data basis for curve drawing.

[0085] For the sorted displacement sequence {x1,x2,...,x n}, determine the tension value corresponding to each displacement point through interpolation operation (such as linear interpolation, cubic spline interpolation, etc.): for two adjacent known displacement points x i with x i+1 , if there is an intermediate displacement x(x i <x<x i+1 ), then the tension value F(x) corresponding to the displacement is calculated according to the interpolation function Finterp(x), so that the displacement and tension form a one-to-one mapping discrete data pair {(x1,F1),(x2,F2),...,(x n ,F n )}.

[0086] The discrete data pairs are input into a curve fitting 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 the displacement x and the dependent variable is the tension F. During the fitting process, the fitting order must be controlled (e.g., a third-order polynomial) to avoid overfitting and ensure that the curve truly reflects the nonlinear relationship between displacement and tension (e.g., the nonlinear characteristics of rebound force). At the same time, smoothing is used to eliminate minor fluctuations that may remain after interpolation, ensuring that the curve is continuous and free of significant abrupt changes.

[0087] Calculate the goodness of fit of the fitted curve to the target data after supplementation (such as R 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 does not meet the standard, the curve returns to reinterpolate or adjust the filter parameters until the curve meets the accuracy requirements.

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

[0089] Establishing a displacement-tension comparison table according to preset calibration points, and obtaining the expected output tension value according to the comparison table and linear interpolation;

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

[0091] The present invention adopts a table lookup method combined with an interpolation method as the main control strategy, establishes a "displacement-tension" comparison table based on preset calibration points, and quickly obtains the desired output tension value through table lookup and linear interpolation during the actual control process, thereby driving the wire drawing motor to work. This method is simple to implement and responds quickly, and is suitable for vehicle-mounted control scenarios with high real-time requirements. In addition, advanced control algorithms such as PID feedback control or fuzzy control can also be used. PID control achieves high-precision dynamic regulation by continuously adjusting the output to minimize the error between the set value and the actual value; fuzzy control is suitable for nonlinear and highly uncertain systems, and can respond more flexibly to complex working condition changes.

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

[0093] Obtain quantitative analysis of empty stroke, maximum stroke, rebound force and their fluctuations;

[0094] The idle stroke is the ineffective movement distance of the brake pedal before the cable motor starts to apply effective tension. The displacement data collected by the displacement sensor and the tension data collected by the tension sensor are analyzed to determine the displacement value corresponding to the time when the tension begins to increase significantly.

[0095] The maximum effective stroke is the maximum distance traveled from the end of the idle stroke to when the brake pedal is fully depressed. The brake pedal is continuously pulled until the displacement reaches a preset threshold or the pulling force reaches a safety upper limit, and the displacement change from the end of the idle stroke to the time when the pulling 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 amplitude of the rebound force change under the same displacement. The standard deviation or range of multiple tension values ​​corresponding to the same displacement in the "displacement-tension" relationship curve is calculated as the quantitative result of the rebound force fluctuation range.

[0098] During the data analysis phase, the system extracts multiple 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 to the moment when the tension increases significantly;

[0100] Idle travel xdead: indicates the ineffective moving distance before the wire pulling motor starts to apply effective pulling force;

[0101] Rebound force curve: describes the trend of tension change during the displacement recovery process when the pedal is released, which 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. Empty stroke calibration (xdead)

[0105] Data preprocessing: On the displacement-tension curve, the displacement interval [x0, x1] before the tension value exceeds the reference threshold (such as 0.5N) for the first time is intercepted.

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

[0107] Result verification: Repeat the test 3 times and take the average value as the final empty stroke calibration value. The error range is controlled within

[0108] Within ±0.5mm.

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

[0110] Stroke termination judgment: When the displacement reaches the preset safety threshold (such as 77mm for cars and 100mm for trucks) or the pulling force reaches the mechanical limit (such as 300N), traction is stopped and the displacement value xmax at this time is recorded.

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

[0112] Redundancy check: Use a pressure sensor to detect the pressure buildup in the brake system to ensure that the pressure value corresponding to xeff reaches more than 95% of the system operating pressure.

[0113] 3. Rebound force characteristic calibration

[0114] Release curve collection: Control the cable motor to release the pedal at a constant speed (e.g., 5 mm / s), and simultaneously record the displacement-tension data to form the rebound force curve Frelease(x) during the release phase.

[0115] Feature point extraction:

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

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

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

[0119] 4. Calibration of rebound force fluctuation range (ΔF)

[0120] Window sliding calculation: Slide a fixed window (such as 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 σmax of σ(F) in all windows.

[0123] Fluctuation range: records the displacement range in which 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 obtaining the travel data and the tension data, the method further includes:

[0127] Input historical calibration data to the vector machine, neural network or regression model for training, and establish a mapping relationship between input variables and output parameters; the variables include displacement, time, and temperature;

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

[0129] Machine learning-based fitting models, such as support vector machines (SVMs), neural networks (NNs), or regression models, are trained on large amounts of historical calibration data to establish mappings 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, enhancing its adaptability and intelligence.

[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 tension Fmotor can be dynamically adjusted based on the calibration results to make it more consistent with 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 force value obtained through calibration. After data is written, the system displays the calibration completion status on the human-machine interface, notifying the user that the calibration operation has been successfully completed. The entire software process enables the cable motor to accurately perceive the brake pedal characteristics and adaptively optimize dynamic control parameters, improving the response speed of the after-installed AEBS cable motor-driven brake pedal.

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

[0134] Displacement measurement uses a displacement sensor, such as a photoelectric, Hall-effect sensor, or encoder, to measure the brake pedal's travel in real time, generating a highly accurate displacement signal x(t) for subsequent data processing and control strategy generation. This method, with its mature structure, fast response, and high stability, is currently the preferred implementation. Alternatively, strain gauge sensors or laser ranging devices can be used to achieve displacement measurement. Strain gauge sensors, attached to the surface of an elastic element, sense deformation and thus indirectly reflect displacement changes. Laser ranging, on the other hand, utilizes non-contact optical principles and is 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 capture the tension value F(t) applied during traction. This method offers intuitive measurement, high accuracy, and ease of integration. Alternatively, a built-in strain gauge bridge circuit can be used. This involves embedding a Wheatstone bridge circuit composed of multiple strain gauges within 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, facilitates system miniaturization and lightweight design, and offers certain cost advantages.

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

[0137] Under the control of the controller, the wire motor pulls the brake pedal at a preset speed to obtain travel data and tension data. The data acquisition frequency of the displacement sensor and the tension sensor is not less than 100 Hz, 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 travel data and the tension data.

[0138] An acquisition frequency of 100Hz or higher can frequently record the displacement changes and tension response of the brake pedal, accurately capturing subtle features of key stages such as nonlinear fluctuations in rebound force and the conversion from empty travel to effective travel. This avoids the loss of critical data due to excessively large sampling intervals and ensures that the "displacement-tension" relationship curve fully reflects the dynamic characteristics of the pedal. Synchronously recording timestamps strictly guarantees the temporal correspondence between the displacement signal x(t) and the tension signal F(t), eliminating deviations in the acquisition timing between the two. This allows the drawn "displacement-tension" relationship curve to truly reflect the pedal state at the same moment, providing accurate spatiotemporal correlation data for the subsequent extraction of key parameters such as empty 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 precise parameters such as the rebound force fluctuation range and effective travel boundaries more reliable. For example, subtle changes in adjacent data points can accurately identify the critical point where tension "significantly increases" (the end of the empty travel), avoiding boundary judgment errors caused by sparse or asynchronous data.

[0140] As can be seen from the above embodiments, this application provides a static calibration method for an on-board cable-operated motor brake pedal based on stroke measurement. By introducing a joint measurement mechanism of a displacement sensor and a tension sensor, combined with 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, key characteristic parameters such as the pedal's idle travel, maximum effective travel, rebound force, and its fluctuation range are quantitatively analyzed, providing a precise 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 pedal's actual operating range and feedback characteristics. Based on these parameters, the control system can formulate a motor control strategy that is more closely aligned with real-world operating conditions, improving the response consistency and controllability of the brake system and avoiding braking force deviations caused by misjudgment of pedal position. The controller dynamically optimizes the cable-operated motor output based on the calibration results. By writing the calibration data to a memory and calling it in real time, the system can automatically adjust the cable-operated motor drive signal to match the current pedal state. This technical content improves the accuracy and stability of the braking response, significantly enhancing driving safety, especially in complex road conditions or emergency braking scenarios. The non-invasive mounting structure design eliminates the need to modify the original vehicle structure for the sensor and actuator; only the measurement device needs to be installed on the pedal linkage component, resulting in strong compatibility and convenient installation. In summary, this invention effectively addresses the control error problem caused by the unclear brake pedal characteristics in traditional aftermarket AEBS solutions by combining scientific and rational sensor configuration, key parameter extraction, and intelligent control strategies.

[0141] Similar parts between the embodiments provided in this application can be referenced to each other. 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 expanded based on the scheme of this application without expending creative work shall fall within the scope of protection of this application.

Claims

1. A static calibration method for a vehicle-mounted cable motor brake pedal based on stroke measurement, characterized in that: The method comprises: Install the cable motor, displacement sensor and tension sensor on the brake pedal linkage mechanism according to the preset positions; Start the wire pulling motor, displacement sensor and tension sensor and initialize them; Under the control of the controller, the cable motor pulls the brake pedal at a preset speed to obtain travel data and tension data; The controller draws a displacement-tension relationship curve based on the collected stroke data and tension data, and extracts key parameters from the relationship curve, wherein the key parameters include idle stroke, maximum effective stroke, rebound force and fluctuation range; Analyzing the key parameters to obtain calibration results, and inputting the calibration results into an automatic emergency braking system; The automatic emergency braking system determines a cable motor control strategy based on the calibration result.

2. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1 is characterized in that: The method comprises: After starting the cable motor, displacement sensor, and tension sensor and initializing them, the pulling speed and direction are determined according to the vehicle model and calibration requirements; The controller starts the wire pulling motor to perform a pulling operation based on the pulling speed and direction, and records the time; When the stop condition is satisfied, the pulling operation is stopped.

3. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 2 is characterized in that: The method further comprises: When the controller starts the wire pulling motor to perform a pulling operation based on the pulling speed and direction, a displacement signal x(t) of the displacement sensor and a tension signal F(t) of the tension sensor are collected, and travel data and tension data are recorded; When the displacement in the travel data is greater than a first preset threshold, and / or when the pulling force in the pulling force data is greater than a second preset threshold, the pulling operation is stopped.

4. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1 is characterized in that: The method further includes Performing high-frequency noise reduction processing on the travel data and the tension data using a sliding average filter or a low-pass filter algorithm to obtain denoised target data; The data points in the target data are supplemented by interpolation operation, and a displacement-tension relationship curve is drawn based on the supplemented target data.

5. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 4 is characterized in that: The method further comprises: Establishing a displacement-tension comparison table according to preset calibration points, and obtaining the expected output tension value according to the comparison table and linear interpolation; The wire pulling motor control strategy is adjusted based on the expected output tension value.

6. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1 is characterized in that: The key parameters extracted from the relationship curve include: Obtain quantitative analysis of empty stroke, maximum stroke, rebound force and their fluctuations; The idle stroke is the ineffective movement distance of the brake pedal before the cable motor starts to apply effective tension. The displacement data collected by the displacement sensor and the tension data collected by the tension sensor are analyzed to determine the displacement value corresponding to the time when the tension begins to increase significantly. The maximum effective stroke is the maximum distance traveled from the end of the idle stroke to when the brake pedal is fully depressed. The brake pedal is continuously pulled until the displacement reaches a preset threshold or the pulling force reaches a safety upper limit, and the displacement change from the end of the idle stroke to the time when the pulling 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 amplitude of the rebound force change under the same displacement. The standard deviation or range of multiple tension values ​​corresponding to the same displacement in the "displacement-tension" relationship curve is calculated as the quantitative result of the rebound force fluctuation range.

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

8. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1 is characterized in that: The method further comprises: In the step of installing the cable motor, displacement sensor and tension sensor on the brake pedal linkage mechanism according to a preset position, the preset position is determined according to the traction pedal force range and the motor winding length range of the vehicle model: for cars and off-road vehicles, adjust the fixed position and anchor point of the cable motor so that the traction pedal force is within the range of 0 to 300N and the motor winding length is within the range of 0 to 77mm; for dump trucks, large trucks and tractors, adjust the fixed position and anchor point of the cable motor so that the traction pedal force is within the range of 0 to 500N and the motor winding length is within the range of 0 to 100mm.

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

10. The static calibration method of the vehicle-mounted cable motor brake pedal based on stroke measurement according to claim 1, characterized in that: The method further comprises: Under the control of the controller, the wire motor pulls the brake pedal at a preset speed to obtain travel data and tension data. The data acquisition frequency of the displacement sensor and the tension sensor is not less than 100 Hz, 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 travel data and the tension data.

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