Pneumatic brake adjusting arm pre-tightening force self-correcting system

Abstract

The invention discloses an air brake adjusting arm pre-tightening force self-correcting system, particularly relates to the technical field of vehicle air brake control, and aims to solve the problem that the pre-tightening force of an air brake adjusting arm cannot be corrected under the condition that a whole vehicle is static and is not disassembled. And due to the influence of air source fluctuation, mechanism abrasion and friction lag, the initial contact of the shoe is difficult to observe, the pre-tightening force is difficult to set in a closed-loop mode, and the consistency and process marks of left and right wheels are insufficient. A unified time base and a calibration window are established under the condition that a whole vehicle is static, composite pressure perturbation and camshaft orthogonal micro-vibration are applied to form pilot frequency excitation, and initial contact of a shoe is judged according to the combination of slope abrupt change, curvature abrupt change, hysteretic area and phase-locked amplitude-phase transition; and carrying out online identification on equivalent stiffness, springback and lagging through a small amount of brake release circulation, and driving a micro-stepping actuator to carry out convergence self-correction on a step angle under temperature rise and springback gating, so that a target pre-tightening window is stably generated, the stroke of a push rod and a brake gap fall into the target pre-tightening window, too tight dragging and too loose over-limit are avoided, and the consistency of left and right wheels of the same bridge is improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle air brake control technology, specifically to an air brake adjusting arm preload self-calibration system. Background Technology

[0002] In existing vehicle air braking systems, the adjusting arm generally adopts a mechanical automatic compensation structure. Some models also incorporate pushrod stroke sensors, air pressure sensors, or remote monitoring to indicate excessive stroke or lining wear during the maintenance cycle. These solutions typically use a static baseline from the factory or during maintenance as a starting point, relying on stroke thresholds, pressure thresholds, or cycle-based logic to trigger adjustments, focusing on the "whether it exceeds the limit" result. On-site verification usually involves lifting or disassembly combined with manual experience for correction. Due to the long-term cumulative effects of factors such as air source fluctuations, temperature drift, diaphragm and seal hysteresis, S-cam and bushing wear clearance, and frictional changes caused by contamination, the mechanical turning point of the "initial contact friction pair" of the brake shoes is difficult to reliably observe without disassembly. This leads to threshold-based methods relying on a single measurement (stroke or pressure only) prone to initial contact misjudgment and inaccurate rebound assessment. Simultaneously, the differences in equivalent stiffness and rebound caused by structural and wear variations between the left and right wheels and front and rear axles are often masked by uniform empirical values, failing to reflect individual deviations.

[0003] Within the aforementioned technical framework, preload is often treated as a static setting during assembly or maintenance, rather than as an observable and controllable object in the context of the entire vehicle. When load, temperature rise, and friction conditions drift over time, the preload can easily become disconnected from the target clearance and pushrod stroke, leading to two opposing risks: "too loose, resulting in excessive stroke" and "too tight, resulting in slight dragging and overheating." Furthermore, even if existing automatic adjustments or remote monitoring trigger compensation operations, there is usually a lack of directly verifiable procedural evidence: when it was triggered, under what pressure and temperature conditions the initial contact was determined, the amount of correction, whether the left and right wheels were synchronized, and whether it was completed within the controlled boundaries. These details often cannot be documented with a unified timing and standard. This makes it difficult to quantify maintenance reviews and annual inspection comparisons, and also increases the cost of handling compliance disputes. Therefore, relying on single-indicator thresholds or fixed experience for clearance and stroke management has a methodological gap with the drift and individual differences inherent in vehicles during their service life.

[0004] Based on the above situation, the technical problem that needs to be solved in this field is: how to robustly identify the "first contact turning point of the brake pads" in the braking transmission chain under the interference background of air source fluctuations, mechanism wear, and friction hysteresis, without disassembly or lifting of the entire vehicle; combining this with online identification of equivalent stiffness and springback characteristics to form an executable preload self-calibration closed loop, ensuring that the pushrod stroke and brake clearance under common operating conditions remain stably within the target range over a long period; and generating traceable calibration process records with unified timing and standardized criteria to facilitate operation, maintenance, and inspection verification. The above technical problem addresses the pain points of current approaches that rely on single threshold judgments, static experience settings, and a lack of evidence chains, which are insufficient to handle actual drift and individual differences, and has clear engineering orientation and application boundaries. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a pneumatic brake adjusting arm preload self-calibration system to solve the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a pneumatic brake adjusting arm preload self-calibration system, comprising: S1, Calibration Management Module: Used to establish a unified time base and calibration window when the vehicle is stationary, load thermal safety budget and stop boundary as constraint benchmarks for subsequent observation and execution; S2, Perturbation Excitation Module: Used to apply composite pressure perturbations constrained by safety budget to the air brake circuit and apply orthogonal mechanical micro-vibrations to the camshaft to form a hetero-frequency excitation sequence to excite a separable response; S3, Observation and Judgment Module: Used to synchronously collect pressure, push rod stroke, cam angle, acceleration and temperature, extract slope change, curvature change, hysteresis loop area transition and phase-locked loop amplitude transition, and determine the initial contact point of the shoe. S4, Parameter Identification Module: Used to recursively identify the equivalent stiffness, rebound time constant and hysteresis coefficient within a preset braking release cycle, and output a time-based reliability result to provide a basis for target setting; S5, Execution Control Module: Used to calculate the target preload window and left and right wheel compensation based on the initial contact point and identification parameters, drive the micro-stepping actuator to converge by step angle, and implement gating with temperature rise rate and springback convergence time; S6, Evidence Collection and Audit Module: Used to solidify calibration standards, criteria, parameters, execution quantities and compliance conclusions, generate time indexes to support operation and maintenance and inspection traceability, and close the self-calibration and compliance evidence chain.

[0007] In a preferred embodiment, S1 includes: Establish a unified time base and calibration window while the vehicle is parked, and load thermal safety budget and stop boundary; Under a unified time base, the bridge position number, wheel position number, ambient temperature, reference pressure, parking status, and mileage marker are acquired and aligned, and steady-state segment truncation, spike removal, and completion according to the redundancy channel consistency rule are performed. Zero vehicle speed and sliding window pressure variance meeting the threshold are used as the conditions for opening the calibration window, and the validity of the calibration window is determined by bus rhythm supervision, parking consistency and sensor channel reliability. When any stop boundary is reached, the perturbation is sequentially canceled, the pressure is returned to the baseline, the unmet entry is solidified, and the session lock is released. Session records containing caliber version, criterion version, threshold version, session number, and time index are generated and stored in a non-volatile storage area using two-stage hardening and digest fingerprint verification readback.

[0008] In a preferred embodiment, S2 includes: Under the condition that the session is valid and a unified time base is established, the perturbation excitation module is configured to apply a composite pressure perturbation consisting of step superimposed sawtooth to the pneumatic brake circuit and to apply orthogonal mechanical micro-vibration around the reference phase to the camshaft. The two excitation frequencies are different and do not have an integer multiple relationship. Under the constraints of thermal safety budget and stop boundary, a heterogeneous excitation sequence is formed on a unified time base to provide a mechanical excitation signal that is independent of the gas pressure channel.

[0009] In a preferred embodiment, the perturbation excitation module is configured to perform zero-point and drift verification on pressure, cam angle, temperature and acceleration before entering the observation window, and after alignment under a unified time base, remove start-stop edges and hysteresis tails and mark the removal intervals. Waveform fidelity and angular amplitude stability are used as quality judgment thresholds; The stimulus instruction set and execution trajectory are permanently recorded using an idempotent key composed of session number, bridge number, wheel number and time index; The vehicle bus communication unit triggers a fallback to the calibration management module when both control frame confirmation and status frame confirmation are not achieved.

[0010] In a preferred embodiment, S3 includes: Within a unified time base and calibration window, the observation and judgment module simultaneously acquires pressure, push rod stroke, cam angle, acceleration, and temperature during the heterogeneous excitation sequence formed by composite pressure perturbation and orthogonal mechanical vibration. Smoothing and drift subtraction are performed within the feature window and missing measurements are marked. Slope abrupt change, curvature abrupt change, hysteresis loop area transition, and phase-locked amplitude-phase transition are calculated in the time neighborhood window. The initial contact point of the shoe is determined based on the criterion version and the threshold version, and an initial contact record containing the session number, bridge position number, wheel position number, time index, initial contact time, initial contact displacement, and initial contact angle is generated. The computed digest fingerprint is embedded in the session feature region, and notification and deduplication are accomplished by carrying idempotent keys in the event frame.

[0011] In a preferred embodiment, S4 includes: Within a unified time base and calibration window, the parameter identification module, constrained by thermal safety budget and stop boundary, acquires the pressure, push rod stroke, and cam angle timing of the brake release cycle based on the initial contact record of the brake shoe. It performs cycle alignment, outlier removal, and saturation segment truncation. Within the observation window, it recursively identifies the equivalent stiffness, rebound time constant, and hysteresis coefficient, generates a confidence result, and labels the time index. Triggering is implemented based on the minimum number of cycles, and stopping is implemented based on the convergence threshold and the maximum number of cycles. A set of mechanical parameters containing session number, bridge position number, wheel position number, time index, and caliber version number is generated, stored in the parameter area and registered in the session directory, and published through parameter announcement frames. The parameters are deduplicated and traced using an idempotent key composed of session number, bridge position number, wheel position number, and time index.

[0012] In a preferred embodiment, S5 includes: Within a unified time base and effective session, the execution control module calculates the target preload window and left and right wheel compensation based on the initial contact record and mechanical parameter set, eliminates sudden jump segments, and drives the micro-stepping actuator to converge gradually according to the minimum angular step distance. After each step, the state is determined based on the gating of the temperature rise rate and the rebound convergence time, and corresponding measures are taken to continue, pause, or enter the safety cone. When any safety caliber touches the boundary, the most recent step is canceled and the state is restored to the previous step. At the same time, an adjustment record containing the number of steps, total angle, left and right wheel compensation, temperature rise trajectory, rebound time trajectory and time index is generated and submitted to the evidence collection and auditing module.

[0013] In a preferred embodiment, during the step angle convergence process, the execution control module determines the tight side based on the joint criterion of initial contact displacement and convergence step number, performs reverse yielding on the tight side, and verifies the synchronization deviation of the left and right wheels. The same bridge is operated independently according to the wheel position sequence; Interact via vehicle bus using a fixed field sequence and broadcast compliance upon achieving the target; In the event of a power outage, the mechanical self-locking mechanism maintains the current position; upon power restoration, the playback is checked according to the time index. When a record is triggered repeatedly, it is deduplicated using an idempotent key consisting of the session number, bridge number, wheel number, and time index, retaining only the first record that meets the criteria and establishing a reference relationship.

[0014] In a preferred embodiment, S6 includes: Based on a unified time base, calibration criteria, parameters, execution quantities, and compliance conclusions are aggregated into structured records and version locked. A time index is generated and a chain of evidence is established based on the session number, unified time base timestamp, and turn position dimension; Records are stored in a non-volatile memory area and a summary fingerprint is generated; Idempotent deduplication is performed while maintaining order constraints by using the session number, bridge number, wheel number, and time index as idempotent keys; Register and perform two-way reconciliation on the fleet management terminal based on time index and summary fingerprint; Provides a retrieval interface for fixed content based on session number, bridge number, and wheel number.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. By establishing a unified time base and calibration window in the static state of the whole vehicle, the heterogeneous excitation of composite pressure micro-perturbation and camshaft orthogonal mechanical micro-vibration is adopted. The initial contact point of the shoe is robustly determined by a combination of criteria including slope change, curvature change, hysteresis loop area transition and phase-locked loop amplitude and phase transition. Then, the equivalent stiffness, springback time constant and hysteresis coefficient are identified online within a small number of brake release cycles. The micro-stepping actuator is driven to perform step angle convergence self-calibration under temperature rise and springback gating. This achieves stable generation of the target preload window under the interference of air source fluctuation, mechanism wear and friction hysteresis, and makes the push rod stroke and brake clearance fall into the window, avoiding excessive tightness and excessive looseness, and improving the consistency of the left and right wheels of the same axle.

[0016] 2. By implementing version locking for calibration calibrators, criteria, parameters, and execution quantities, establishing an evidence chain with time indexes and summary fingerprints, and solidifying session records with idempotent deduplication, sequence constraints, and offline reconciliation mechanisms, the entire calibration process and conclusions are made traceable, verifiable, and auditable. This facilitates consistent access during operation and maintenance and annual inspections, reduces miscalibration disputes and compliance risks, and supports long-term stable application for large-scale fleets. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preload self-calibration system for a pneumatic brake adjusting arm according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example: Figure 1 A flowchart of a self-calibrating system for the preload of a pneumatic brake adjusting arm is provided. The system includes: S1, Calibration Management Module: Used to establish a unified time base and calibration window when the vehicle is stationary, load thermal safety budget and stop boundary as constraint benchmarks for subsequent observation and execution; S2, Perturbation Excitation Module: Used to apply composite pressure perturbations constrained by safety budget to the air brake circuit and apply orthogonal mechanical micro-vibrations to the camshaft to form a hetero-frequency excitation sequence to excite a separable response; S3, Observation and Judgment Module: Used to synchronously collect pressure, push rod stroke, cam angle, acceleration and temperature, extract slope change, curvature change, hysteresis loop area transition and phase-locked loop amplitude transition, and determine the initial contact point of the shoe. S4, Parameter Identification Module: Used to recursively identify the equivalent stiffness, rebound time constant and hysteresis coefficient within a preset braking release cycle, and output a time-based reliability result to provide a basis for target setting; S5, Execution Control Module: Used to calculate the target preload window and left and right wheel compensation based on the initial contact point and identification parameters, drive the micro-stepping actuator to converge by step angle, and implement gating with temperature rise rate and springback convergence time; S6, Evidence Collection and Audit Module: Used to solidify calibration standards, criteria, parameters, execution quantities and compliance conclusions, generate time indexes to support operation and maintenance and inspection traceability, and close the self-calibration and compliance evidence chain.

[0020] The technical connections and implementation logic of the six modules are as follows: In a stationary vehicle scenario, the system operates in a closed loop from "S1→S6": S1 first establishes a unified time base and calibration window, loads the thermal safety budget and stop boundary, completes the alignment and steady-state confirmation of the bridge position number, wheel position number, and environmental and reference quantities, and forms a session baseline as a constraint for the entire process; on this baseline, S2 applies a composite pressure perturbation consisting of step superimposed sawtooth to the air brake circuit and applies orthogonal mechanical micro-vibration to the camshaft, so that the two paths form a heterogeneous excitation sequence under a unified time base, which is used to excite the separable response; S3 synchronously collects pressure, pushrod stroke, cam angle, acceleration and temperature during this excitation, extracts the combined features of slope change, curvature change, hysteresis loop area transition and phase-locked loop amplitude-phase transition, and determines the initial contact point of the shoe. The system generates an initial contact record; S4 uses the initial contact record as an anchor point to recursively identify the equivalent stiffness, rebound time constant, and hysteresis coefficient within a preset braking release cycle, outputs and labels the reliability results with time indexes, and forms a set of mechanical parameters to provide a basis for target setting; then S5 calculates the target preload window and left and right wheel compensation based on the initial contact record and the set of mechanical parameters, drives the micro-stepping actuator to converge at the minimum angular step distance, and gates the stepping and yielding with the temperature rise rate and rebound convergence time, and generates an adjustment record after the target is achieved; finally S6 locks and solidifies the calibration caliber, criteria, parameters, execution amount, and achievement conclusions, connects the evidence chain based on the time index, and provides retrieval and reconciliation, so that the self-calibration process is closed and traceable within the safety boundary.

[0021] S1, Calibration Management Module: Used to establish a unified time base and calibration window when the vehicle is stationary, load thermal safety budget and stop boundary as constraint benchmarks for subsequent observation and execution. Specific implementation is as follows: When the vehicle is parked and the road surface is flat, the calibration management module establishes a unified time base and calibration window, so that subsequent observations and actions are performed under the same caliber, and the thermal safety budget and stop boundary are loaded simultaneously. The unified time base is a millisecond-level alignment mechanism based on the high stability clock of the vehicle controller. Preferably, the main control crystal oscillator performs temperature compensation on the bus timestamp and performs a self-calibration once after power-on. The allowable single-point deviation can be set to not exceed one sampling period, and the cumulative drift within the whole window can be set to not exceed two sampling periods. If the time base self-calibration fails or the temperature compensation deviation exceeds the limit, the time base is determined to be unusable, the window is prohibited from entering, and the unusable entry is recorded.

[0022] The calibration window is a time period during which the vehicle is stationary and environmental disturbances are controlled, preferably set to 30 to 60 seconds. The module obtains the bridge position number, wheel position number, ambient temperature (in degrees Celsius), reference pressure (in kilopascals), parking status, and mileage from the vehicle network. The sampling rhythm is preferably 100 times per second, and the tolerance is given by the vehicle self-test table and the vehicle model parameter library and locked in the firmware. At the same time, the minimum resolution and allowable error band of the metering link are loaded, covering four types of measurements: pressure, temperature, push rod stroke, and cam angle. Its caliber comes from the vehicle model parameter library and calibration table and is version locked. The metering traceability record is fixed along with the session record.

[0023] Temperature sampling is preferably achieved using a thin-film sensor mounted on the outside of the brake backplate, near the main heat flow channel. High-temperature resistant bonding and mechanical limiting are employed, with thermal response time and installation torque locked according to the vehicle model database. Pressure measurement is preferably located at the branch near the wheel end after the valve, with the sampling port and throttle element number locked in the vehicle model database. When pre-valve measurement is used, the measurement point segment is marked in the session log. Before entering the window, all quantities are aligned under a unified time base. Steady-state segment truncation and peak removal are performed first, followed by filling short-term missing measurements with the nearest reliable segment and marking the filling boundary. The nearest reliable segment is preferably taken from the nearest stable window of the same sensor, with a maximum backtracking time of no more than five seconds. When redundant channels exist, they can be filled preferentially based on their consistency, and the filling source is written in the session log. Redundant channel consistency is determined by a combined threshold of the mean difference, standard deviation ratio, and correlation coefficient within the sliding window; all three conditions must be met for consistency to be considered, and this threshold is locked in the vehicle model database. The allowable gap is no more than five sampling cycles; exceeding this limit invalidates the window and terminates the session. The window trigger condition is that the vehicle speed is zero and the pressure variance is lower than the limit. The pressure variance limit is determined by a sliding window. The sliding window length is preferably one to two seconds and the update step is preferably 0.1 seconds. The threshold is derived from the vehicle model database and calibration table and is locked in the firmware version. The steady-state segment is based on a combination of three factors, namely, within a continuous interval of not less than two seconds, the window mean drift of the benchmark pressure is not greater than the preset drift limit, the window variance is continuously lower than the threshold, and the vehicle speed is continuously zero.

[0024] Bus rhythm monitoring is measured by the percentile threshold of the time interval between adjacent state frames relative to the desired rhythm. This threshold is given by the vehicle model database and locked in the firmware. Monitoring failure is recorded as bus jitter exceeding the limit. Parking consistency is defined as the percentage of samples within a window that meet the parking and zero wheel speed conditions, preferably reaching 100% within the effective window. When the vehicle speed signal and parking signal are inconsistent, the vehicle speed is used as the decision root, the window is deemed invalid, and a safe shutdown sequence is executed, while the conflict entry is fixed. The criterion for sensor channel reliability is synthesized by three factors: the percentage of effective samples within the sliding window, the percentile value of the measurement residual, and the consistency of redundant channels, weighted according to version locking. The threshold is derived from the vehicle model database and is version locked.

[0025] The window stops when any safety threshold is reached, including when the temperature rise rate reaches the budget, the maximum temperature reaches the upper limit, the pressure variance or bus jitter exceeds the limit, the parking consistency decreases, and the sensor channel reliability falls below the threshold. When the threshold is reached, the perturbation is removed in the safe shutdown sequence, the pressure is returned to the reference pressure, the unmet item is fixed, and the session lock is released. The value range of the minimum safe pressure is derived from the brake circuit design data and is version locked in the vehicle model database. Preferably, it is loaded at the beginning of the session and used as the reference for the return in the safe shutdown sequence.

[0026] After completing steady-state assessment and budget loading within the window, the module generates a session record and a time index. The session record is a structured record organized around a calibration process, including caliber version, criterion version, threshold version, firmware version, session number, time index, vehicle type identifier, bridge position number, wheel position number, ambient temperature, reference pressure, temperature rise budget, maximum temperature limit, sampling rhythm, tolerance caliber, metrological resolution and error band, steady-state assessment results, window start and end times, and window validity identifier. The time index consists of the session start timestamp and sequence number, used for retrieval and idempotency across upstream and downstream modules. The session number is generated by concatenating the vehicle type identifier, bridge position number, wheel position number, and time index to ensure uniqueness within the system.

[0027] The aforementioned records are preferably stored in the non-volatile area of ​​the controller. A two-stage solidification and verification readback are used to ensure that the records are consistent with the summary fingerprint, and a directory entry is established according to the time index. The capacity of the non-volatile area can be set to store at least thirty valid session records, and the retention period can be set to at least six months. When the capacity is below the lower limit, new sessions are prohibited and a dump is prompted. The elimination adopts a first-in-first-out strategy. Before elimination, the summary fingerprint calculation and fleet mirror reconciliation are completed. During cross-reboot, the session lock and idempotent key are maintained in the non-volatile area. After reboot, the session lock state is restored first. In case of idempotent conflict, the first solidified record is used. Only the reference relationship is registered and the original time index is returned. Existing entries are not overwritten.

[0028] To ensure evidence retention, the module generates summary fingerprints for the caliber version and key fields, which are then fixed in the session directory. The summary fingerprint generates a fixed-length verification string based on the caliber version and key fields according to a fixed field sequence. Its length and generation caliber are version-locked in the firmware for mirror reconciliation and integrity verification. In case of fingerprint inconsistencies, the first fixed record prevails, and the conflict entry is registered. Simultaneously, a mirror image is maintained on the fleet management end, and periodic reconciliation is performed using the summary fingerprint. Evidence access is controlled by permissions. On the vehicle end, only maintenance roles are allowed to read key fields. On the fleet end, retrieval is performed through a controlled interface by session number and time index. Access behavior is also fixed as an audit entry. Upstream and downstream communication is conducted via the vehicle bus frame, using command frames and status frames for round trips. The communication latency is preferably set to 200 milliseconds to ensure multiple rounds of status exchange are completed within a single window. Resource scheduling is performed sequentially on the same bridge, without cross-bridge concurrency. Cross-bridge execution proceeds in a queue, with retrying up to three times for failures. Cooling intervals are inserted between retries to meet thermal safety budget requirements.

[0029] The verification criteria are used for window validity review, including pressure stability (measured by sliding window statistics of pressure variance), temperature stability (measured by budget constraints of temperature rise rate and maximum temperature), and parking consistency (measured by sample proportion). Preferably, the number of statistical samples within a single valid window is no less than one thousand. In a preferred embodiment, the ambient temperature can be set to 25 degrees Celsius, the reference pressure to 700 kPa, the temperature rise budget to 3 degrees Celsius per minute, the maximum temperature limit to 90 degrees Celsius, the sampling rate to 100 times per second, and the window duration to 45 seconds. Under these conditions, the module completes steady-state evaluation in the first five seconds, confirming that the pressure variance is within the threshold and the parking consistency meets the requirements. Then, the window is triggered and the budget is loaded. Subsequently, a session record and time index are generated, and the summary fingerprint is calculated and verified within two seconds. The entire session completes upstream and downstream interaction within a communication latency constraint of no more than 200 milliseconds. When the window ends, a valid identifier is output and the directory item and fingerprint are solidified, providing a traceable, auditable, and version-locked session baseline for subsequent perturbation excitation, observation judgment, parameter identification, and execution control.

[0030] S2, Perturbation Excitation Module: Used to apply composite pressure perturbations constrained by safety budgets to the air brake circuit and to apply orthogonal mechanical micro-vibrations to the camshaft, forming a hetero-frequency excitation sequence to excite a separable response. Specifically, the implementation is as follows: Under the premise that the calibration management has confirmed the validity of the session, in a scenario where the vehicle is stationary, the air source is stable, and a unified time base has been established, a composite pressure perturbation is applied to the air brake circuit, while orthogonal mechanical micro-vibration is applied to the camshaft. This ensures that the two types of excitations are asynchronous in frequency, forming a heterogeneous excitation sequence. This allows for the excitation of a separable structural response without disassembly, facilitating subsequent differentiation of frictional hysteresis and structural stiffness based on phase-locked loop amplitude and phase characteristics, and supporting the determination of the shoe's initial contact point and identification of mechanical parameters. Specifically, the composite pressure perturbation refers to the superposition of a small-amplitude step and a short-period, small-amplitude sawtooth waveform near the reference air pressure, with amplitude and rhythm constrained by thermal safety budgets and stop boundaries. The orthogonal mechanical micro-vibration refers to two-phase angular perturbations around the camshaft reference phase, with stable amplitude and fixed phase. The mechanical excitation channels are independent of the air pressure channel; the different frequency excitation sequence means that the fundamental frequency and harmonic components of the two types of excitations do not overlap in the time domain, so as to ensure that the phase-locked loop amplitude and phase characteristics can be robustly separated under a unified time base; the unified time base means that the sampling time of pressure, push rod stroke, cam angle, acceleration and temperature are aligned to millisecond resolution based on the high-precision clock of the vehicle controller; the thermal safety budget refers to the permissible range of the drum back temperature rise rate and the maximum temperature; the stop boundary refers to the boundary that terminates the current session when any safety limit is reached; the session is valid means that the four checks of calibration window, parking status, air source steady state and time index are all qualified and idempotent keys have been generated; the drum back temperature refers to the temperature of the fixed measuring point on the outer surface of the brake drum back plate, and the measuring point position is locked according to the vehicle calibration table.

[0031] Before implementation, it is preferable to perform zero-point and drift verification on pressure, angle, temperature and vibration pickup. The calibration record is written into the session directory with time index and locked together with the caliber version. The periodic calibration of sensors and actuators can be set to be locked with mileage or session count. If the threshold is exceeded, an automatic prompt will be given and excitation will be prohibited. The calibration strategy is fixed with the caliber version. Implementing this excitation requires obtaining reference pressure, step amplitude and rhythm, sawtooth amplitude and period, mechanical micro-vibration amplitude and frequency, etc., in units of kilopascals, milliseconds, degrees and hertz, respectively. The default values ​​can be set to the corresponding version of the axle type and wheel position in the vehicle model library and vehicle calibration table. Both the vehicle model library and vehicle calibration table have version numbers and are locked with the session. Any caliber value is written to the time index according to the version number for traceability. Preferably, the range, accuracy and temperature drift level of the pressure sensor, the minimum resolution and hysteresis range of the cam angle encoder, and the installation position and posture of the accelerometer are defined and locked in the vehicle model library and vehicle calibration table. The accelerometer should be arranged near the axis of the adjustment arm to improve vibration pickup reliability. The minimum step angle, allowable hysteresis, maximum cumulative adjustment angle and maximum number of steps of the microstepping actuator are fixed as execution capability boundaries and registered with the session. At the same time, the lower limit of torque is listed in the vehicle model library to ensure self-locking stability in the non-calibrated state.

[0032] To ensure comparability in subsequent analyses, all raw quantities are aligned to a unified time base before entering the observation window. Actuator start / stop edge segments and hysteresis tails are removed, and the removal intervals are marked. Pressure and angle signals are preferably sampled at 10 to 100 Hz, and acceleration and temperature signals are preferably sampled at 10 Hz, all aligned to a unified time base at the millisecond level. The synchronization accuracy and allowable drift of the unified time base are preferably no less than one millisecond, and the cumulative drift in a single session is no higher than the upper limit locked by the version. The number of effective sampling points in each observation window is no less than a preset lower limit, and the minimum sample size rule is clearly defined according to the vehicle model database and statistical version, preferably 200 to 500 points per window, to ensure statistical validity of the quality inspection. The observation window covers several perturbation cycles to form a robust response, preferably ten to twenty cycles; the trigger condition is that the session is valid and the thermal safety budget is available, while checking that the ambient temperature, ambient humidity and supply air dew point are within the allowable range given by the vehicle calibration table threshold version; the stop condition is that the temperature rise rate reaches the upper limit of the thermal safety budget, the drum back temperature reaches the upper limit of the allowable range, or the rebound convergence time exceeds the boundary; the rebound convergence time can be set to the convergence time when the fluctuation of stroke or angular velocity falls into the qualified window given by the vehicle calibration table threshold version and is maintained continuously for several sampling cycles within a fixed time window, and this caliber is locked with the threshold version; the maximum duration and minimum cooling interval of a single session are given by the vehicle calibration table threshold version and locked with the version, and the session exits at the stop boundary when either boundary is reached.

[0033] To avoid cross-wheel coupling and bridge-side thermal overlap, this step adopts single-wheel sequential execution. The cross-bridge serial strategy defaults to the previous axle followed by the next, proceeding from smallest to largest bridge position code. When the vehicle structure does not meet this sequential condition, execution is performed incrementally according to the session number. The above order is locked by the vehicle calibration table. To ensure real-time communication and execution, the round-trip delay between control frames and status frames can be set to the millisecond level, preferably not exceeding one hundred milliseconds. If a transmission is not acknowledged, it can be retried once. If it is still not acknowledged, it will fall back to calibration management and write an unready flag for maintenance verification. The communication frame preferably includes the session number, bridge position number, wheel position number, time index, caliber version, and status code fields. Unacknowledged frames are deduplicated using an idempotent key and the retry sequence number is recorded.

[0034] During the excitation execution, waveform fidelity and amplitude stability are used as the quality inspection criteria: waveform fidelity is judged comprehensively based on the three qualified windows of amplitude deviation, period deviation and phase drift, and amplitude stability is judged based on the amplitude statistical fluctuation window. The qualified windows are all clearly defined as the vehicle calibration table threshold version and locked with the version. The composite pressure perturbation is preferably formed by small throttling and micro energy storage chamber or their equivalent elements. The pressure resistance level, temperature resistance level and leakage rate limit of small throttling and micro energy storage chamber are given in the vehicle calibration table threshold version and locked with the version. The waveform fidelity is self-checked and verified before and after excitation, and the verification record is written to the session directory.

[0035] Upon completion, two types of products are generated under a unified time base: one is the excitation instruction set, recording the reference pressure, step caliber, sawtooth caliber, angle caliber, frequency caliber, thermal safety budget, stop boundary, and time index of this session; the other is the execution trajectory, recording the pressure sequence, angle sequence, temperature trajectory, and confirmation timestamps of control frames and status frames. Both types of products are stored in a hierarchical session directory with an idempotent key composed of session number, bridge position number, wheel position number, and time index. Calibration version and threshold version are used for locking and generating summary fingerprints. The observation and judgment process directly calls the citation number, without repeatedly issuing calibers to avoid ambiguity. To ensure consistency and traceability, This step employs an idempotent key deduplication strategy, retaining only the first successful record after repeated triggers and establishing a reference relationship within the session directory; status codes use a predefined error code system and are registered, including at least three categories: mechanical actuation not ready, communication interruption, and control frame loss, with the set locked with each version; electromagnetic compatibility level, protection level, and wiring harness routing path are clearly defined in the vehicle calibration table and locked with each version to ensure the stability of sampling and actuation under electromagnetic interference and environmental exposure; the record retention period and record completeness target of the session directory are defined in the vehicle model database and registered with each session, with the record completeness target preferably being 100%, and the minimum queryable years preferably not less than twice the statutory inspection period.

[0036] If mechanical micro-vibration conditions are limited, a highly sensitive acoustic pickup can be installed on the adjusting arm seat. The energy transition of the wheel end micro-elastic impact can be used as a corroborating signal for the difference in frequency with the air pressure perturbation. This alternative path maintains consistency with the mechanical micro-vibration path in terms of time index, field set, version locking, and quality inspection criteria, and is written into the same session directory, with the evidence chain structure remaining unchanged. Preferably, the step amplitude range is locked by the vehicle calibration table threshold version and should be between 10 and 30 kPa; the sawtooth amplitude range should be between 5 and 15 kPa; the sawtooth period range should be between 80 and 120 milliseconds; the mechanical micro-vibration angular amplitude range should be between 0.05 and 0.15 degrees; the mechanical micro-vibration frequency range should be between 10 and 20 Hz; and the number of consecutive cycles should be 12. Up to twenty; if the drum back temperature rises to approximately one degree per minute and the amplitude fluctuation falls within the qualified window given by the vehicle calibration table threshold version, then the waveform fidelity and amplitude stability are recorded as qualified; when the valve group opening and closing delay exceeds the vehicle model database threshold, any actuator self-test item fails, or the bus confirmation does not return after being allowed to retry, this step reverts to calibration management, retaining the in-ready flag and session directory for review or the next session trigger; when the excitation quality is qualified and the product solidification is completed, the observation and judgment stage can read the execution trajectory under the same time index to carry out feature extraction, thereby ensuring that the evidence chain of the initial contact point judgment of the shoe and subsequent parameter identification corresponds one-to-one, is consistent, verifiable, and traceable.

[0037] S3, Observation and Judgment Module: Used to synchronously collect pressure, push rod stroke, cam angle, acceleration, and temperature; extract slope abrupt changes, curvature abrupt changes, hysteresis loop area transitions, and phase-locked loop amplitude-phase transitions; and determine the initial contact point of the shoe. Specific implementation is as follows: Within a session with an established time base and calibration window, pressure (kPa), push rod stroke (mm), cam angle (degrees), acceleration (m / s²), and temperature (degrees Celsius) are simultaneously acquired during the excitation sequence formed by the combined effects of composite pressure perturbations and orthogonal mechanical vibrations. All quantities are aligned with a unified time base. The unified time base is based on the highly stable clock of the vehicle controller, and the multi-channel timestamps are corrected to millisecond-level consistency. Preferably, the alignment accuracy can be set to no more than one millisecond. When the alignment residual exceeds this value, the feature calculation for this session is paused and a "not aligned" flag is written. To ensure a clear judgment caliber, smoothing and drift subtraction are first performed within the feature window to suppress high-frequency noise and slow baseline shift. Missing samples are only marked and not interpolated to avoid spurious signals. The feature window covers the complete excitation sequence, and its range can be set from two to five seconds, locked by the session time index.

[0038] Feature calculation is triggered only if the "signal steady state" is achieved. The steady state criteria can be set as follows: the baseline pressure variance should not exceed a threshold, the temperature rise rate should not exceed a threshold, and there should be no monotonic drift in angle and stroke. Feature extraction will begin after three consecutive perturbation cycles if these criteria are met. The upper limit cycle can be set to ten to twenty perturbation cycles, and will stop once one of them is reached. To ensure measurement capability, the pressure range and resolution, stroke and angle resolution, temperature response time, and acceleration range can be set to the minimum capability boundaries given by the vehicle model library. When any channel is below the minimum capability boundary, the session will not enter feature calculation and will write a channel capability deficiency flag. The noise floor can be set as the statistical dispersion of the steady-state baseline segment within the feature window and locked according to the criterion version. All thresholds are determined by adding a conservative amount of device resolution to this dispersion.

[0039] Four types of characteristics are evaluated under a unified time base and time neighborhood window and a unified threshold is adopted: slope abrupt change is when the first-order rate of change of stroke with respect to pressure exceeds the threshold within the time neighborhood window; curvature abrupt change is when the second-order rate of change of the above relationship exceeds the threshold within the time neighborhood window; hysteresis loop area transition is when the closed area formed by loading and unloading in the stroke-pressure plane during the same perturbation cycle crosses the threshold compared to the previous cycle, which is used to reflect the energy difference when overcoming gaps and friction; phase-locked amplitude-phase transition is when the coherent amplitude or phase at the mechanical micro-vibration reference frequency crosses the threshold compared to the previous steady-state level, which is used to reflect the amplitude-phase lock from the no-stroke state to the contact state.

[0040] The time neighborhood window can be set to five to twenty milliseconds; all thresholds can be set to be obtained based on the statistical range of the steady-state baseline segment of this session and superimposed with a conservative amount of device resolution. The default value of the vehicle model library is used for the first session, and then locked according to the criterion version and threshold version, and is not mixed with other sessions. The initial contact point of the brake shoe is determined by the consistency rule of "any two types are satisfied to be valid". The initial contact point of the brake shoe is the physical turning point of the brake shoe when it first contacts the friction pair and its corresponding displacement and angle; the determination also gives a confidence level, which can be set to high, qualified, and low. Among them, at least two types of features exceed the threshold at the same time and the transition direction is consistent, which is marked as high; only one type exceeds or the direction is inconsistent, which is marked as low; the rest are qualified.

[0041] To ensure the quality of excitation and sampling, waveform fidelity can be set as a comprehensive index of amplitude and phase deviation between the command waveform and the measured waveform within the feature window. Exceeding the threshold indicates insufficient fidelity. Timestamp continuity interruption can be set as an interval between adjacent samples exceeding twice the sampling period. Upon detection, the current judgment is immediately stopped and the corresponding error code is recorded. After completion, an initial touch record is generated, including session number, bridge position number, wheel position number, time index, initial touch time, initial touch displacement, initial touch angle, four types of feature transition summaries, credibility level, criterion version number, and threshold version number. A summary fingerprint is calculated on the normalized field string. The summary fingerprint is a fixed-length verification string used for evidence chain consistency verification. Together with the version information and time index, it is stored non-volatilely in the session feature area.

[0042] Upstream and downstream notifications are sent via vehicle bus event frames. The minimum fields include session number, bridge position number, wheel position number, time index, reference number, confidence level, criterion version number, and threshold version number. The end-to-end latency is preferably set to 50 milliseconds. The idempotent key consists of session number, bridge position number, wheel position number, and time index. Duplicate event frames are deduplicated, retaining only the first valid judgment and registering the reference relationship. If two types of features are inconsistent for a long period or the confidence level is low, the composite pressure amplitude and mechanical micro-vibration angle amplitude are automatically reduced according to the safety budget. The reduction ratio can be set to 20% to 30%, and the perturbation period is kept unchanged while resampling is performed. Resampling does not exceed two rounds. If the goal is still not achieved, a failure flag is written and the upstream strategy is transferred. If the vehicle speed is non-zero, the air supply pressure is insufficient, the temperature exceeds the limit, the acquisition is interrupted, or the communication is interrupted, the current judgment is immediately stopped and an error code is recorded. The error codes are uniformly: judgment inconsistency, signal distortion, acquisition interruption, vehicle speed non-zero, air supply insufficient, temperature exceeds the limit, and session does not exist. Among them, signal distortion is determined by any one of the following: insufficient waveform fidelity, sensor saturation, or interruption of timestamp continuity.

[0043] The on-site performance testing criteria include initial touch repeatability, judgment consistency rate, and feature transition significance. The sample size is no less than three independent judgments, which are fixed with each session. Repeatability is measured by the initial touch time and displacement dispersion; consistency rate is measured by the proportion of pairwise combinations of the four types of features; and significance is measured by the ratio of transition amplitude to noise floor. Preferably, for example, with an ambient temperature of 25 degrees Celsius, a reference pressure of 700 kPa, a temperature rise rate of 3 degrees Celsius per minute, and a temperature upper limit of 90 degrees Celsius, the conclusion of slope change and phase-locked phase transition consistency is obtained at the third second, with an initial touch displacement of 0.7 mm. Parameter identification for the same session enters a small loop with the reference number.

[0044] In terms of implementation, the pushrod stroke and cam angle acquisition can be set to magnetic grating, optical grating, or Hall array; temperature can be set to thin-film thermistor or thermocouple; and acceleration can be set to miniature accelerometer. These three can be equivalently replaced when the equivalent accuracy and time base diameter are satisfied. If structural space is limited, a highly sensitive acoustic pickup can be configured on the adjusting arm seat, using the energy transition of the elastic impact at the moment of contact as evidence instead of the phase-locked loop amplitude-phase transition. Other rules and thresholds remain unchanged. Resource and sequence constraints are single-bridge sequential execution without concurrent cross-bridge operations. The number of retries and the upper limit of latency are locked with the session record. The retention period for session records and initial contact records can be set to be no shorter than the vehicle's lifespan or regulatory requirements. The decimal precision of the recorded fields is locked according to the measurement list and serves as one of the steps in the summary fingerprint normalization process. After all records are locally stored, they can be reconciled with the fleet management terminal according to the strategy. Any copy can be used for auditing and annual inspection.

[0045] S4, Parameter Identification Module: Used to recursively identify the equivalent stiffness, rebound time constant, and hysteresis coefficient within a preset braking release cycle, and outputs time-based reliability results to provide a basis for target setting. Specific implementation is as follows: Mechanical parameter identification is performed while the vehicle is parked and within the calibration window, which refers to the time period when the vehicle speed is zero and air pressure and temperature fluctuations are controlled. This step organizes all measurements under a unified time base, which is the millisecond-level time reference of the on-board controller, to ensure that the timing of pressure, push rod stroke and cam angle are aligned on the same time coordinate. It also inherits the thermal safety budget and stop boundary from the calibration management as hard gating. The thermal safety budget limits the permissible range of temperature rise rate and maximum temperature, and the stop boundary stipulates that the current session will be terminated if any safety threshold is exceeded.

[0046] The information sources are the initial contact records of the brake shoes and the timing of pressure, stroke, and angle during several braking and release cycles. A braking-release cycle refers to a complete process from pressurization to stabilization, then to full release and back to stabilization. A stable segment refers to a time window within which the first-order rate of change of pressure and displacement are within the threshold values ​​given in the vehicle model database. Full release refers to the pushrod displacement and drum back temperature returning to the stable segment and maintaining a minimum holding time. The minimum holding time is locked as an entry in the vehicle model database and managed according to version. Before identification, preferably, cycle alignment, outlier removal, and saturation segment truncation are performed: cycle alignment uses the initial contact time and the starting point of the stable segment as benchmarks to overlap the key moments of each cycle on a unified time base; outlier removal marks and excludes samples whose instantaneous values ​​or characteristic values ​​exceed the tolerance zone of the vehicle model database; saturation segment truncation is used to remove displacement saturation and angle stop segments near the end position or lock-up zone to avoid inelastic effects.

[0047] The observation window covers several complete cycles, preferably three to five cycles. The trigger condition is that a complete cycle with a number not less than the minimum cycle count has been obtained and the thermal safety budget is met. The stopping condition is that the change amplitude of any target parameter is continuously lower than the convergence threshold or reaches the maximum cycle count. The minimum cycle count, maximum cycle count, and convergence threshold are all locked as vehicle model library entries. Within the above observation window, the equivalent stiffness, springback time constant, and hysteresis coefficient are recursively identified and their reliability is given. The equivalent stiffness is used to characterize the elastic zone's resistance to deformation after initial contact, the springback time constant is used to characterize the recovery speed after release, the hysteresis coefficient is used to characterize the difference between the pressurization path and the release path within the same cycle, and the reliability is used to quantify the acceptability of this identification and its value is between zero and one. The allowable range and default value of the parameters are provided by the vehicle model library and the material manual. The vehicle model library is a calibration set for specific vehicle models, including allowable ranges, tolerances, recommended rhythms, and the aforementioned caliber entries. The material manual is a specification of the material properties and permissible working range of key components.

[0048] After identification is completed, a set of mechanical parameters is generated, including equivalent stiffness, rebound time constant, hysteresis coefficient, reliability, session number, axle position number and wheel position number, time index, and caliber version number. The session number is a unique identifier for a complete calibration process; the axle position number and wheel position number are used to locate the two wheels on the same axle; the time index is a unique time identifier for a single identification within a session; and the version number is used to lock the calibration caliber, criterion caliber, and execution strategy caliber used. This set of mechanical parameters is stored in a unified format in the parameter area and registered in the session directory. The parameter area is a non-volatile namespace within the controller used to store the set of mechanical parameters, and the session directory is a collection of records organized by session number. The unified format refers to structured records with consistent field naming, units, and precision. Unit calibers include pressure (kPa), displacement (mm), angle (°), time (milliseconds), and reliability (zero to one dimensionless). The range and minimum resolution of pressure, displacement, angle, and temperature are inherited from the sensor configuration caliber in the general instruction manual and recorded as precision entries in the vehicle model database, locked together with the version number of this section to ensure the feasibility of the identification criteria. Upstream and downstream connections are completed via the vehicle bus using parameter notification frames. These frames carry the session number, bridge position number, wheel position number, time index, and version number, and are preferably published within 100 milliseconds.

[0049] To ensure traceability and deduplication, an idempotent key is constructed using the session number, bridge position number, wheel position number, and time index. The character set of the idempotent key can be set to numbers and uppercase letters, and its length is preferably no less than a predetermined lower limit. When a duplicate request is received, deduplication is performed using the idempotent key, retaining only the first successful record and establishing a reference relationship. If parameter drift exceeds the drift threshold or the confidence level is lower than the acceptable confidence level in the observation window, the excitation amplitude can be reduced and the data can be collected again in a new observation window. The original identified entry is marked as a review item, and the time index is retained. The drift threshold and the acceptable confidence level are both vehicle model database entries and are locked with the version. If the number of loops is less than the minimum number of loops or the data collection is incomplete, a failure flag indicating insufficient samples is returned, and the current session ends. If a record with the same version number already exists under the same idempotent key, it is registered as a version conflict, and the first valid record is retained.

[0050] Safety and compliance boundary requirements stipulate that identification should not be performed when the vehicle is moving, the air source pressure is below the minimum safe pressure, or the temperature exceeds the thermal safety budget. If any boundary is triggered, the session will be registered in the session directory and the session will be exited. The verification criteria include parameter stability and reproducibility. Parameter stability refers to the dispersion of the target parameter within the same observation window being lower than the limit given in the vehicle model library. Reproducibility refers to the difference between two wheels on the same axle under the same criteria being within the allowable deviation. The sample size is based on two wheels on the same axle.

[0051] The capability and scope are reflected in the fact that this step can identify the equivalent stiffness, rebound time constant, and hysteresis coefficient for each wheel position within a limited number of cycles under a unified time base, perform reliability assessment, version locking, and parameter notification, and complete on-site implementation with controlled latency under resource constraints. Preferably, the representative process can be set to achieve convergence in three cycles, with a high level of reliability. Subsequently, the execution control module calculates the target preload window and the compensation amount of the left and right wheels based on the mechanical parameter set. In scenarios where parameters are difficult to converge over a long period, small-amplitude perturbation segmented identification can be adopted, dividing the elastic interval into several sub-segments to obtain sub-parameters segment by segment, and then merging them into a set of parameters under a unified time base to meet continuity and stability. Version locking and summary fingerprint registration are performed on the merged caliber to improve the integrity and auditability of the evidence chain. The allowable upper and lower limits of the sampling rhythm and the upper limit of the clock alignment error are given by the vehicle model library and used as hard gating within this session. Once the clock alignment error exceeds the upper limit, the identification of the current wheel position will be terminated immediately, and the reason for the stop boundary trigger will be registered in the session directory.

[0052] The upper limit of the allowable missing measurement ratio and the upper limit of the outlier ratio for each observation window are given by the vehicle model database. When any indicator in any window exceeds the upper limit, a sample supplementation flag is returned. The convergence threshold, credibility qualification threshold, minimum number of cycles, maximum number of cycles, minimum hold time, and drift threshold are written as vehicle model database entries and are written into the mechanical parameter set along with the version number of this section to achieve version locking. The precision and byte order description of each field are supplemented in the parameter area record. Deduplication and traceability are uniformly performed using an idempotent key composed of session number, bridge position number, wheel position number, and time index.

[0053] S5, Execution Control Module: This module calculates the target preload window and left / right wheel compensation based on the initial contact point and identification parameters, drives the micro-stepping actuator to converge by step angle, and implements gating based on the temperature rise rate and springback convergence time. Specifically, it is implemented as follows: Within a unified time base and effective session, the target preload window and left and right wheel compensation amounts are calculated based on the initial contact record and mechanical parameter set obtained in the preceding sequence, and the micro-stepping actuator is driven to approach the target in a step angle convergence manner. Among them, the target preload window is the allowable range of preload force and brake clearance determined by the equivalent stiffness, rebound time constant and hysteresis coefficient; the left and right wheel compensation amounts are the difference correction required to achieve consistency between the two wheels of the same axle; step angle convergence is the way in which the actuator approaches the target range one by one according to the minimum angular step distance; the temperature rise rate is the growth rate of the temperature of the brake drum back or liner area with respect to time; the rebound convergence time is the time required for the stroke and angle to return to the steady state threshold after the brake is released; the safety budget is the permissible set of temperature rise rate, maximum temperature, single step angle and total number of steps; and the stop boundary is the boundary at which the calibration of this round is terminated when any budget item is touched.

[0054] After the system reads the target pretension window and the compensation amount of the left and right wheels from the parameter notification, it first performs consistency verification of the session number, bridge position number and wheel position number and removes abrupt segments caused by air source fluctuations or sensor transients. It can be set to use short window smoothing and stable segment extraction to determine the first step reference value. The observation window of the continuous stepping stage is preferably no more than ten steps. The trigger condition is that the parameter credibility meets the standard. The parameter credibility is formed based on the consistency of multiple cycle identifications and the size of the residual amount. It is preferably not less than 0.8. When the credibility is low, the step angle is automatically reduced and the observation window is extended. The upper limit of the step angle and the upper limit of the single correction amount are given by the mechanism capability table. The default value comes from the vehicle model library. It is preferably that the single step angle is not greater than 0.1 degrees, the minimum angle resolution is not less than 0.05 degrees, and the upper limit of the total number of steps is not greater than twelve steps. Each step is subject to temperature rise rate and rebound convergence time gating. It is preferably that the upper limit of the temperature rise rate can be set to three degrees per minute, the upper limit of the maximum temperature of the brake drum back can be set to ninety degrees, and the rebound convergence time threshold can be set to not more than one second.

[0055] If the gate fails to pass, the process pauses, reduces the step angle, or enters a safety cone. The safety cone represents a conservative range where a smaller step angle and a longer cooling interval are used when approaching the stop boundary. Preferably, the step angle is half of the previous step, and the cooling interval is not less than 30 seconds. The stopping condition is that the target pre-tightening window is met and maintained for two consecutive times. Maintaining means that after two consecutive steps, the stroke and angle are both within the target pre-tightening window and the fluctuation does not exceed 0.05 mm, or either safety caliber touches the boundary. When the boundary is touched, the angle correction of the most recent step is immediately canceled and the state of the previous step is returned. Preferably, the cancellation amount is a reverse retreat of one step angle and a mark indicating that the target has not been met. An adjustment record is generated during the execution. The adjustment record is a set of items used for auditing in this session, including the number of steps, total angle, left and right wheel compensation, temperature rise trajectory, rebound time trajectory, target achievement conclusion, and time index. It is archived in the non-volatile area by session number and pushed to the evidence audit module for version locking and evidence chain solidification.

[0056] On the vehicle bus, control frames are used to issue step and gating commands, and status frames are used to report travel, angle, and temperature. Upon reaching the target, a pass broadcast is issued. Messages use a fixed field order and field check bits to ensure consistent interpretation. The round-trip delay between a single-step command and report is preferably no more than 200 milliseconds. If jitter occurs, two retries can be made within a short period. The retry interval can be set to 300 to 500 milliseconds, and a backoff strategy can be enabled to avoid overcorrection. The synchronization deviation of the left and right wheels is mainly measured by the difference in pushrod travel between the two wheels of the same axle, in millimeters. Preferably, the threshold is no greater than 0.05, which can be supplemented by cams. Angle difference verification, in degrees, is performed. The side with the smaller initial contact displacement or more convergence steps is judged as the tighter side. The tighter side is given priority to be yielded and the consistency is re-verified. The temperature measuring point is preferably set on the inner side of the brake drum back or the back plate of the lining. It adopts the attached or non-contact sensing, with a range covering -40 to 150 degrees Celsius and an accuracy of 0.5 degrees Celsius. The sampling rhythm is consistent with the unified time base. The range and accuracy of push rod stroke and cam angle are based on the vehicle model database. The stroke resolution is preferably 0.01 mm and the angle resolution is preferably 0.05 degrees. After factory calibration, the identifier is written in the first frame of the session.

[0057] The minimum step angle of the actuator is given by the mechanism capability table. The allowable hysteresis range is expressed by the equivalent clearance diameter, preferably not greater than 0.05 mm. It can be set to verify the first reverse microstep and record the hysteresis compensation amount. In the power failure state, the mechanical self-locking is maintained, and the holding force range is registered in the model database. After the power is restored, the most recent step is replayed and checked according to the time index. The unified time base frequency and accuracy are preferably at the millisecond level. The allowable drift range is controlled within the session. In the event of a power failure or reset, it is restored to the previous qualified or unqualified boundary using the session number and time index. The capacity limit of the single session adjustment record is registered in the local non-volatile area. When the limit is reached, it can be set to first-in-first-out or prohibit overwriting and alarm. The solidified record generates a fixed-length fingerprint in an irreversible digest manner and is archived together with the version number.

[0058] The environmental adaptability range is linked to the safety budget. Step angle convergence can only begin when temperature, humidity, salt spray, and vibration are within the registered range. If they exceed the limits, the pause and retreat strategy is maintained. The two wheels on the same bridge do not execute concurrently, but advance in the order of wheel positions. When duplicate triggering is detected based on idempotency keys, only the first record of compliance is retained and a reference relationship is established. Merging two records is prohibited to ensure the consistency of the evidence chain. Error identification is recorded in text format and bound to the frame field, including step loss, temperature rise exceeding the limit, synchronization exceeding the tolerance, and retreat failure. When these occur, the trigger time and handling measures are recorded in the adjustment record. The preferred embodiment can be set to a target gap of 0.5 to 0.7 mm, a retreat of one step angle on the tighter side, a total of eight steps to complete, a maximum temperature rise rate of one degree per minute, and a rebound convergence time that is stable within the threshold. The above values ​​are used to demonstrate representative working conditions within the capability and range.

[0059] The implementation can be an actuator combining magnetically held microstepping and mechanical self-locking. It maintains self-locking during non-calibration to improve vibration resistance and stability. An alternative approach is to use a worm gear subdivision mechanism or a micro-tooth disc ratchet differential mechanism to obtain comparable minimum angular resolution and self-locking capability. The entire process follows safety and compliance boundaries, and is not executed when the vehicle is moving, the air pressure is insufficient, or the friction material is below the wear limit. It does not exceed the temperature rise and step budget, and does not bypass the stop boundary. When any boundary is triggered, it prioritizes retreat and leaves a record. The above terminology and scope are consistent with the causal chain of calibration management, perturbation excitation, observation judgment, parameter identification, execution control, and evidence collection and auditing in the independent claims.

[0060] S6. Evidence Collection and Audit Module: Used to solidify calibration standards, criteria, parameters, execution quantities, and compliance conclusions; generate time indexes to support operation and maintenance and inspection traceability; and close the self-calibration and compliance evidence chain. Specific implementation is as follows: To ensure that the self-calibration results are traceable, verifiable, and usable for regulatory review, the calibration criteria, criteria, parameters, execution quantities, and achievement conclusions are solidified and version locked at the end of the session, and an evidence chain is established based on the time index. The session is a continuous self-calibration process with a unified time base defined by a millisecond-level alignment reference under the high stability clock of the vehicle controller. The calibration criteria are the set of definitions used in this self-calibration, including the measurement range, sampling rhythm, alignment and denoising rules, threshold sources, and allowable deviations. The criteria are the combination of features and threshold configurations used to determine the initial contact point and safety trigger of the tire shoes. The parameters are the equivalent stiffness, rebound time constant, and hysteresis coefficient and their reliability identified in the small cycle. The execution quantities are the cumulative number of steps, total angle, left and right wheel compensation, temperature rise trajectory, and rebound time trajectory in the micro-stepping stage. The achievement conclusion is the judgment result that stably falls into the target preload window and simultaneously meets the consistency of the left and right wheels and the thermal safety budget.

[0061] During the solidification process, the above entries, along with vehicle type, mileage, and roadside markings, are aggregated into a structured record. Field names and units remain consistent throughout the session. Pressure is measured in kilopascals, temperature in degrees Celsius, time in milliseconds, stroke in millimeters, angular displacement in angles, and rhythm in Hertz. Missing fields are not filled with values ​​but are marked with placeholders and the fill-in limits are noted. Simultaneously, version locking is implemented for calibration caliber version, criterion version, parameter version, execution strategy version, and threshold version. The execution strategy version includes a combination configuration of step angle upper limit, step rhythm, yield strategy, and safety cone gating. The threshold version includes a complete set of sources for temperature rise rate upper limit, maximum temperature, rebound convergence time limit, and synchronization deviation limit.

[0062] The time index is generated by combining the session number, unified time base timestamp, and wheel position dimension. It is used to connect the original measurement segment reference number, feature summary, parameter set, and adjustment record into an evidence chain according to the order of occurrence, ensuring consistent positioning across devices and time periods. All fixed records are preferably completed shortly after the session ends, covering both local storage and remote registration. After being written to disk in a non-volatile area, a summary fingerprint is generated for content consistency verification. The summary fingerprint uses a fixed-length summary representation and is locked along with the summary fingerprint version number. The fixed completion time can be set to no more than ten seconds. The single session occupancy can be set to a range of three hundred to eight hundred kilobytes, with the upper limit derived from the fleet capacity budget and recorded synchronously with the version lock. The drift of the unified time base relative to the time index is preferably set to five to ten milliseconds. The time index source is only the unified time base and cannot be manually rewritten.

[0063] When the network is unstable, the system can be configured to first solidify the data locally and then reconcile it bidirectionally with the fleet management terminal. The reconciliation is performed using the time index as the primary key and the summary fingerprint as the secondary key. The retry rhythm can be set to once every five to ten minutes, with a cumulative total of no more than three to six times. If the limit is exceeded, conflicting copies are retained and processing is delayed. To prevent duplicate writes and sequence disorder, an idempotent key is formed using the session number, bridge position number, wheel position number, and time index. The data is processed serially within the same bridge and in a preset sequence across bridges. Repeated triggers are deduplicated using the idempotent key, retaining only the first record of compliance and appending references to subsequent records. When a replay occurs, the order is determined by the time index. Restore the order without overwriting existing records; when searching externally, return fixed content by session number, bridge position number, and wheel position number. The field list preferably includes session number, time index, vehicle type, mileage, roadside markings, calibration caliber version, criterion version, parameter version, execution strategy version, threshold version, initial contact record reference number, feature summary, equivalent stiffness, rebound time constant, hysteresis coefficient, confidence level, target pretension window, left and right wheel compensation amount, step angle and step number, temperature rise trajectory summary, rebound time trajectory summary, achievement conclusion and summary fingerprint. Additional extended fields are allowed, but locked versions must not be overwritten.

[0064] The minimum retention time is preferably set to five to ten years, the capacity of the non-volatile area is preferably set to the range of fifty to five hundred megabytes, the power-loss retention time is preferably set to no less than ten years, and the write / erase durability is preferably set to no less than one hundred thousand cycles. The specific values ​​are based on the device specifications and the vehicle self-test table. To strengthen the control of summary consistency, the summary fingerprint length is preferably set to no less than thirty-two bytes, and the statistical collision probability threshold is preferably set to no more than one in a million. The safety and compliance boundaries include not forging the time index, not tampering with the version number, and not marking compliance when the wear of the friction material is below the lower limit or the air source pressure is below the minimum safety value. The minimum safety value is derived from the vehicle model database and the applicable regulatory scope and is locked with the threshold version. If any boundary is triggered, the solidification will stop and the reason will be recorded.

[0065] The on-site inspection criteria include three items: record completeness rate, index traceability rate, and summary fingerprint verification pass rate. The sample size is calculated per session and must include at least one complete session record. The fleet side can summarize and statistically analyze the data monthly. The thresholds for all three items are preferably set to 100%. To facilitate fault handling, an error code set is retained and its occurrence time index and retry count are persisted. Error codes include storage and solidification failure, inconsistent summary fingerprint, idempotent key conflict, communication interruption, session non-existence, and control frame loss. A tiered retry is initiated and a read-only conflict copy is retained until reconciliation is completed or manual review is performed.

[0066] In terms of implementation, equivalent replacements are allowed without changing the functional purpose and boundary constraints. Local storage can use various power-off retention media, and the digest fingerprint can use various fixed-length digest methods. The fleet management terminal can be centralized or distributed. As long as a unified time base, version locking, idempotent deduplication order, and evidence chain integrity are maintained, it is considered equivalent. Through the disclosure of the above capabilities and scope, calibration criteria, judgments, parameters, execution volume, and compliance conclusions can be implemented under unified terminology and a unified time base, achieving one-time disk storage, version locking, evidence chaining, key-based retrieval, and cross-terminal consistency. This can meet the requirements of operation and maintenance review, regulatory spot checks, and compliance audits for authenticity, completeness, and traceability.

[0067] All calculations involved in the embodiments are dimensionless numerical calculations, and the preset parameters and thresholds in the calculations are set by those skilled in the art according to the actual situation.

[0068] It should be noted that this invention can be deployed on the device itself to realize embedded applications, or it can run on a PC or other terminal with a user interface, thereby meeting various hardware environments and usage requirements.

[0069] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions according to the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. Computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wireless or wired transmission; wired transmission methods include optical fiber, twisted pair, coaxial cable, etc.; wireless transmission includes infrared, microwave, etc. Computer-readable storage media can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more sets of available media. Available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media. Semiconductor media can be solid-state drives.

[0070] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0071] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0072] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0073] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0074] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0076] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas brake adjust arm pre-load self-check system, characterized by, Comprise: S1, calibration management module: for establishing a unified time base and calibration window in the whole vehicle stationary state, loading thermal safety budget and stop boundary, as the constraint reference of subsequent observation and execution; S2, perturbation excitation module: for applying a composite pressure perturbation to the air brake circuit, which is constrained by the safety budget, and applying an orthogonal mechanical micro-vibration to the camshaft, forming an excitation sequence of different frequencies to excite separable response; S3, observation and judgment module: for synchronous acquisition of pressure, push rod stroke, cam angle, acceleration and temperature, extraction of slope mutation, curvature mutation, hysteresis loop area transition and phase-locked amplitude and phase transition, judgment of shoe initial contact point; S4, parameter identification module: for recursive identification of equivalent stiffness, rebound time constant and hysteresis coefficient within the preset brake release cycle, and output of time-based reliability results to provide basis for target setting; S5, execution control module: for calculating target pre-tightening window and left and right wheel compensation according to initial contact point and identification parameters, driving micro-step actuator to converge by step angle, and implementing gating according to temperature rise rate and rebound convergence time; S6, evidence audit module: for solidifying calibration aperture, criterion, parameter, execution amount and compliance conclusion, generating time index to support operation and maintenance and traceability, and closing self-calibration and compliance evidence chain.

2. A gas brake adjust arm pre-load self-check system as defined in claim 1 wherein, S1 comprises: Establishing a unified time base and calibration window in the whole vehicle stationary state and loading thermal safety budget and stop boundary; Under the unified time base, obtaining and aligning bridge number, wheel number, environment temperature, reference pressure, stationary state, mileage identification, executing steady-state segment interception, peak elimination and filling according to redundancy channel consistency rules; Taking zero vehicle speed and sliding window pressure variance meeting threshold value as calibration window opening condition, and supervising bus rhythm, stationary consistency and sensor channel reliability to determine calibration window effectiveness; When any stop boundary is touched, sequentially cancel perturbation, fall back to reference pressure, solidify unachieved items and release session lock; Generating session record containing aperture version, criterion version, threshold version, session number and time index, and storing session record in non-volatile storage area by two-stage solidification and summary fingerprint verification readback.

3. A gas brake adjust arm pre-load self-check system as defined in claim 1 wherein S2 Comprise: The perturbation excitation module is configured to apply a composite pressure perturbation composed of step superposition sawtooth to the air brake circuit and an orthogonal mechanical micro-vibration around the reference phase to the camshaft under the condition that the session is valid and the unified time base is established; The two excitation frequencies are different and do not have an integer multiple relationship, and under the constraint of thermal safety budget and stop boundary, an excitation sequence of different frequencies is formed under the unified time base to provide a mechanical excitation signal independent of the air pressure channel.

4. A gas brake adjust arm pre-load self-check system as defined in claim 3 wherein: The perturbation excitation module is configured to perform zero point and drift review on pressure, cam angle, temperature and acceleration before entering the observation window, and under the unified time base, the start-stop edge and hysteresis tail are eliminated after alignment and the elimination interval is marked; Taking waveform fidelity and angular amplitude stability as quality judgment threshold; The excitation instruction set and execution trajectory are recorded by power key solidification according to session number, bridge number, wheel number and time index; The vehicle-mounted bus communication unit triggers rollback to the calibration management module when the control frame confirmation is not achieved and the state frame confirmation is not achieved.

5. A gas brake adjust arm pre-load self-check system as described in claim 1 wherein S3 Comprise: The observation determination module synchronously collects pressure, push rod stroke, cam angle, acceleration, and temperature during the hetero-frequency excitation sequence formed by the composite pressure perturbation and the orthogonal mechanical micro-vibration within the unified time base and the calibration window; Smooth and drift removal are performed within the feature window, and missing data are marked. The slope jump, curvature jump, hysteresis loop area transition, and phase-locked amplitude and phase transition are calculated within the time neighborhood window; The initial contact point of the shoe is determined according to the criterion version and the threshold version, and an initial contact record containing the session number, bridge position number, wheel position number, time index, initial contact time, initial contact displacement, and initial contact angle is generated; The summary fingerprint is solidified in the session feature area, and the notification and deduplication are completed by the event frame carrying the idempotent key.

6. A gas brake adjust arm pre-load self-check system as described in claim 1, wherein S4 It includes: The parameter identification module obtains the pressure, push rod stroke, and cam angle time sequence of the brake release cycle based on the initial contact record of the shoe within the unified time base and the calibration window, constrained by the thermal safety budget and the stop boundary, performs cycle alignment, outlier removal, and saturation segment truncation, recursively identifies the equivalent stiffness, rebound time constant, and hysteresis coefficient within the observation window, and generates a reliability result and marks the time index; Triggering is implemented according to the minimum cycle number criterion, and stopping is implemented according to the convergence threshold criterion and the maximum cycle number criterion; A mechanical parameter set containing the session number, bridge position number, wheel position number, time index, and criterion version number is formed and stored in the parameter area and registered in the session directory, and is published through the parameter notification frame, and is deduplicated and traced back according to the idempotent key composed of the session number, bridge position number, wheel position number, and time index.

7. A gas brake adjust arm pre-load self-checking system as defined in claim 1 wherein S5 It includes: The execution control module calculates the target pre-tightening window and left and right wheel compensation amounts according to the initial contact record and the mechanical parameter set within the unified time base and the effective session, removes the sudden jump segment, and drives the micro-step actuator to gradually converge according to the minimum angle step distance; After each step, the state is determined according to the gate of the temperature rise rate and the rebound convergence time, and the corresponding measures of continuing, pausing, and entering the safety cone are taken respectively; When any safety criterion is touched, the last step is canceled and the state is restored to the previous step, and an adjustment record containing the step number, angle total amount, left and right wheel compensation amounts, temperature rise trajectory, rebound time trajectory, and time index is generated and submitted to the evidence audit module.

8. A gas brake adjust arm pre-load self-check system as defined in claim 7 wherein: During the step angle convergence process, the execution control module determines the tight side according to the joint criterion of the initial contact displacement and the convergence step number, and implements reverse retreat on the tight side and reviews the left and right wheel synchronization deviation; The same bridge is independently executed according to the wheel position sequence; The fixed field order is interacted through the vehicle-mounted bus, and the compliance broadcast is published when the standard is met; Power failure maintains the current position by mechanical self-locking, and after recovery, the position is played back and checked according to the time index; When the trigger is repeated, the idempotent key composed of the session number, bridge position number, wheel position number, and time index is used for deduplication, and only the first compliance record is retained and a reference relationship is established.

9. A gas brake adjust arm pre-load self-checking system as defined in claim 1 wherein S6 It includes: The calibration criterion, parameter, execution amount, and compliance conclusion are aggregated into a structured record according to the unified time base and the version is locked; The time index is generated according to the session number, unified time base timestamp, and wheel position dimension, and the evidence chain is established; The record is solidified in the non-volatile storage area and the summary fingerprint is generated; The idempotent key is implemented by the idempotent deduplication and the order constraint is maintained according to the session number, bridge position number, wheel position number, and time index; The time index and the summary fingerprint are registered and bidirectional reconciliation is performed on the fleet management end. A retrieval interface for solidified content is provided according to session number, bridge location number, and wheel location number. A retrieval interface for solidified content is provided according to session number, bridge location number, and wheel location number.

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