A method for calibrating a large-torque vehicle shift line and shift strategy

Abstract

A calibration method for shift lines and shift strategies in high-torque vehicles, belonging to the field of transmission control technology, is disclosed. The method includes: constructing a multi-objective optimization model and designing a dynamic shift line; building a bench test system and establishing a calibration database; iteratively optimizing the shift line parameters based on the calibration database; verifying and comparing performance under multiple operating conditions in a real vehicle; adjusting the shift line parameters in real time and dynamically adjusting the calibration strategy based on the real vehicle verification results; writing the optimized calibration strategy into the transmission control unit and conducting durability tests. This invention allows the hydraulic torque converter to operate in the high-efficiency range for longer periods, improving ride smoothness. It overcomes the limitations of traditional fixed shift lines, enabling the vehicle to automatically maintain the optimal balance between power output and fuel economy under complex road conditions such as urban congestion, highway cruising, and mountain climbing, improving driving adaptability and enhancing the stability and reliability of the vehicle under long-term high-intensity, high-torque usage scenarios.

Description

Technical Field

[0001] This invention relates to a calibration method for shift lines and shift strategies of high-torque vehicles, belonging to the field of transmission control technology. Background Technology

[0002] With the surge in demand for high torque output from new energy vehicles and heavy-duty vehicles, the shortcomings of traditional shift line design and calibration strategies in adapting to complex operating conditions are becoming increasingly apparent. Existing technologies often rely on empirical rules or single-condition calibration, resulting in poor torque adaptability, insufficient shift smoothness, and significant power interruption. This makes it difficult for vehicles to balance power, economy, and smoothness under high torque scenarios such as heavy loads, hill climbing, and rapid acceleration, specifically manifesting as weak acceleration, high energy consumption, and significant shift shock.

[0003] Existing shift line design methods lack a dynamic adaptive mechanism for real-time torque changes and road conditions (such as slope), and cannot adjust the shift point position in real time according to actual operating parameters. This leads to a decline in driving quality under complex road conditions (such as continuous slopes and frequent starts and stops), and makes it difficult to balance transmission system efficiency and ride comfort.

[0004] Shift parameters calibrated based on fixed rules or experience have significant adaptation defects under high torque conditions. Specifically, this manifests as low hydraulic torque converter efficiency, easy excess of clutch slippage work, and insufficient control of shift shock. These deficiencies make it difficult to meet the dual requirements of transmission system durability and power transmission efficiency under high torque conditions, thus limiting the optimization potential of the vehicle's power economy.

[0005] The root cause of the aforementioned technical defects lies in the fact that traditional methods have not established a dynamic coupling mechanism between torque, road conditions, and shifting strategies, which makes it impossible for the shifting logic to adapt to the multi-parameter coordination requirements under high torque scenarios, ultimately affecting the overall improvement of the vehicle's power economy. Summary of the Invention

[0006] To address the problems existing in the background art, the present invention provides a calibration method for shift lines and shift strategies of high-torque vehicles.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a calibration method for shift lines and shift strategies of high-torque vehicles, the method comprising the following steps:

[0008] S1: Construct a multi-objective optimization model that integrates the high torque characteristics of the engine, and design a dynamic shift line;

[0009] S101: Determine the optimization objective and constraints;

[0010] The optimization objectives are to maximize the efficiency of the transmission system, minimize the shift shock, and minimize the clutch slippage work.

[0011] The constraints include the engine's maximum torque output range, the hydraulic torque converter's high-efficiency range, the pump wheel to turbine speed ratio range, and the clutch slippage work threshold.

[0012] S102: Establish a multi-objective optimization mathematical model;

[0013] S10201: Constructing a multi-objective function using the weighted summation method:

[0014] (1)

[0015] In formula (1):

[0016] This represents the comprehensive evaluation function value for multi-objective optimization.

[0017] For the efficiency of the hydraulic torque converter;

[0018] Normalized impact;

[0019] To normalize the gliding friction work;

[0020] All represent weighting coefficients;

[0021] S10202: Establish a two-dimensional matrix of throttle opening and vehicle speed as the basic shift line. Within the range of 0%-100% throttle opening, divide the intervals into 5% intervals. Each interval corresponds to the vehicle speed threshold for upshifting and downshifting.

[0022] S103: Design dynamic correction factor.

[0023] S10301: Designed with a large torque correction factor, it dynamically adjusts the shift point based on the ratio of the engine's real-time torque to its rated torque. When this ratio is greater than 1.2, the upshift speed is delayed by 5%-10%.

[0024] S10302: Design a slope compensation coefficient correction factor. Obtain slope information through vehicle tilt sensor, establish a slope-shift offset mapping table, and complete the compensation adjustment of shift point based on slope sensor data to correct upshift speed in real time.

[0025] S2: Build a bench test system to simulate high torque conditions, collect standardized transmission system operating data, and establish a calibration foundation database;

[0026] S201: Set up a bench test platform;

[0027] S202: Simulates high torque conditions and collects data;

[0028] S203: Data Processing and Database Construction.

[0029] S3: Based on the calibration database, the GBDT algorithm is used to iteratively optimize the shift line parameters and generate a calibration strategy adapted to high torque scenarios;

[0030] S301: Feature and Label Definitions:

[0031] The algorithm input features are defined as throttle opening, vehicle speed, engine torque, torque converter speed ratio, and gradient.

[0032] The output labels are defined as the vehicle speed offset at the optimal shift point and the torque correction coefficient;

[0033] S302: Iterative Optimization of GBDT Algorithm:

[0034] S30201: Set algorithm hyperparameters;

[0035] S30202: Using the impact and friction work in the database as loss functions, the model parameters are iteratively updated using the gradient descent method. With power performance, economy and smoothness as optimization objectives, the shift point speed offset, torque correction coefficient and slope compensation coefficient are iteratively optimized.

[0036] S30203: Generate calibration strategies adapted to high torque scenarios, including shift lag / advance rules for different torque levels and dynamic control strategies for torque converter lock-up points.

[0037] S4: Real-vehicle multi-condition verification and performance comparison;

[0038] S401: Experimental Design and Data Acquisition

[0039] Three types of typical test routes were selected, including congested urban roads, highway cruising roads, and mountain climbing roads.

[0040] Install a vehicle data acquisition system to record vehicle performance data, including power performance, economy performance, and ride comfort performance.

[0041] Simultaneously, data on engine output torque, hydraulic torque converter transmission efficiency, and clutch slippage work are collected.

[0042] S402: Performance comparison and verification.

[0043] S5: Based on real vehicle verification results, the shift line parameters are corrected in real time through the Kalman filter algorithm, and the calibration strategy is dynamically adjusted to achieve a dynamic balance between power and economy under complex road conditions.

[0044] S501: Establish the state-space model:

[0045] Define state vector ,in: This is the vehicle speed offset at the gear shift point. This is the torque correction factor;

[0046] Define observation vector ,in Impact level;

[0047] S502: Kalman filter recursive calculation:

[0048] Prediction steps:

[0049] (2)

[0050] (3)

[0051] Update steps:

[0052] (4)

[0053] (5)

[0054] (6)

[0055] In equations (2)-(6):

[0056] For discrete sampling times;

[0057] This refers to the previous sampling time.

[0058] These are prior predictions;

[0059] for The prior state prediction at time 1;

[0060] This is the state transition matrix;

[0061] for The posterior optimal value of the state at time 1;

[0062] To control the input matrix;

[0063] for Real-time operating condition input at any given moment;

[0064] for The prior estimate of the covariance matrix at time t;

[0065] for The posterior estimated covariance matrix at time t;

[0066] State transition matrix The transpose of the matrix;

[0067] The process noise covariance matrix;

[0068] for Kalman gain at time step;

[0069] The observation matrix;

[0070] Observation matrix The transpose of the matrix;

[0071] To observe the noise covariance matrix;

[0072] for The posterior optimal value of the state at time 1;

[0073] for The measured observation vector at time;

[0074] The theoretical observed values ​​are calculated based on the shift parameters predicted a priori.

[0075] for The posterior estimated covariance matrix at time t;

[0076] It is the identity matrix;

[0077] S503: Dynamic Adjustment Strategy

[0078] The shift line parameters are adjusted in real time based on the filtered output results. When heavy-load climbing conditions are detected, the torque correction factor is increased and upshifting is delayed to maintain power.

[0079] S6: Write the optimized calibration strategy into the transmission control unit and conduct durability tests to verify the stability and reliability of the calibration strategy under long-term high torque conditions.

[0080] S601: TCU software integration;

[0081] S602: Durability test verification:

[0082] Conduct road durability tests with a cumulative mileage of ≥10,000 km, covering scenarios such as high-speed ring roads, reinforced bad roads, and mountain roads; check the impact resistance and skid friction performance indicators every 1,000 km to confirm that there are no deviations or performance degradation;

[0083] After the test, the full-cycle operation data recorded by the TCU was analyzed to verify the stability and reliability of the calibration strategy under long-term high torque conditions.

[0084] Compared with the prior art, the beneficial effects of the present invention are:

[0085] 1. This invention fundamentally solves the contradictions of insufficient power, poor economy, and large shift shock in traditional shifting strategies under high torque scenarios by constructing a multi-objective optimization model that integrates engine high torque characteristics, transmission efficiency, and ride comfort constraints, and combining it with GBDT data-driven algorithms for precise calibration. Under conditions such as heavy-load start-up and hill climbing, the vehicle accelerates more quickly, the torque converter can operate in the high-efficiency range for a longer period of time, and the shift shock is stably controlled within the comfort threshold of ≤10m / s³, significantly improving ride comfort.

[0086] 2. This invention introduces a large torque correction factor based on real-time torque and a slope compensation coefficient based on a slope sensor, and uses a Kalman filter algorithm for online parameter fine-tuning, enabling the shift strategy to have real-time operating condition perception and dynamic adjustment capabilities. The system can intelligently advance or delay shift points based on the current vehicle load, torque request, and road slope, dynamically optimizing the torque converter lock-up timing. This overcomes the limitations of traditional fixed shift lines, allowing the vehicle to automatically maintain the optimal balance between power output and fuel economy in complex road conditions such as urban congestion, highway cruising, and mountain climbing, thus improving driving adaptability.

[0087] 3. In the model construction and calibration process, this invention uses the clutch slippage work threshold and transmission system impact as hard constraints to ensure that all shifting actions are within the safe tolerance range of mechanical components. The calibration strategy, optimized through multi-condition verification on real vehicles and long-mileage durability tests (≥10,000 km), effectively avoids problems such as clutch overheating and excessive impact loads caused by high-torque shifting after being written into the TCU, protecting key components of the transmission system and improving the stability and reliability of the vehicle under long-term high-intensity, high-torque usage scenarios. Attached Figure Description

[0088] Figure 1 This is a flowchart of the present invention;

[0089] Figure 2 This is a flowchart of S1 of the present invention;

[0090] Figure 3 This is a flowchart of S3 of the present invention. Detailed Implementation

[0091] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0092] A method for calibrating shift lines and shift strategies for high-torque vehicles, the method comprising the following steps:

[0093] S1: Construct a multi-objective optimization model that integrates the high torque characteristics of the engine and design a dynamic shift line; comprehensively consider the core influencing factors under high torque conditions, determine the optimization objectives and constraints, establish a mathematical model for multi-objective optimization, and design the basic shift line and various correction factors to complete the design of the dynamic shift line.

[0094] S101: Determine the optimization objective and constraints;

[0095] The optimization objectives are to maximize the efficiency of the transmission system, minimize the shift shock (the target value of the shift shock is ≤10m / s³), and minimize the clutch slip friction work.

[0096] The constraints include the engine's maximum torque output range (e.g., 1800-2500 rpm), the high-efficiency range of the hydraulic torque converter (efficiency ≥ 85%), the pump wheel to turbine speed ratio range (0.8-1.2), and the clutch slippage work threshold (≤ 300 J).

[0097] S102: Establish a multi-objective optimization mathematical model;

[0098] S10201: Constructing a multi-objective function using the weighted summation method:

[0099] (1)

[0100] In formula (1):

[0101] This represents the comprehensive evaluation function value for multi-objective optimization.

[0102] For the efficiency of the hydraulic torque converter;

[0103] Normalized impact;

[0104] To normalize the gliding friction work;

[0105] All represent weighting coefficients, with values ​​of 0.5, 0.3, and 0.2 respectively.

[0106] S10202: Establish a two-dimensional matrix of throttle opening and vehicle speed as the basic shift line. Within the range of 0%-100% throttle opening, divide the interval into 5% intervals. Each interval corresponds to the vehicle speed threshold for upshifting and downshifting. Generate upshifting / downshifting vehicle speed thresholds under different throttle openings through interpolation algorithm.

[0107] S103: Design dynamic correction factor.

[0108] S10301: Designed with a large torque correction factor, it dynamically adjusts the shift point based on the ratio of the engine's real-time torque to its rated torque. When this ratio is greater than 1.2, the upshift speed is delayed by 5%-10%.

[0109] S10302: Design a slope compensation coefficient correction factor. Obtain slope information through vehicle tilt sensor, establish a slope-shift offset mapping table, and complete the compensation adjustment of shift point based on slope sensor data to correct upshift speed in real time.

[0110] S2: Build a bench test system to simulate high torque conditions, collect standardized transmission system operating data, and establish a calibration database to provide a data foundation for subsequent parameter optimization;

[0111] S201: Set up a bench test platform;

[0112] An experimental platform was built using an engine dynamometer, a gearbox test bench, a hydraulic torque converter simulation device, and a data acquisition system. The data acquisition system had a sampling frequency of ≥1000Hz. Supporting sensors were installed, including a torque sensor with an accuracy of ±0.5%, a speed sensor with an accuracy of ±1rpm, and an acceleration sensor for impact calculation.

[0113] S202: Simulates high torque conditions and collects data;

[0114] Simulates three typical high-torque operating conditions:

[0115] For heavy-load start-up conditions, the vehicle's total mass is increased by 30%, and the throttle opening is 50%-100%.

[0116] Slope climbing conditions, simulating a 5%-15% gradient, duration ≥30s;

[0117] During rapid acceleration, the throttle opening is instantly increased from 20% to 80%.

[0118] During the data acquisition process, the engine output torque / speed, hydraulic torque converter transmission efficiency, clutch slip work, shift shock (calculated by acceleration differential) and transmission system response time (time from shift command to torque stabilization) are recorded simultaneously.

[0119] S203: Data Processing and Database Construction;

[0120] The collected data is filtered and denoised using a low-pass filter with a cutoff frequency of 50Hz. The processed data is stored as a structured calibration database. Each data record includes a working condition label, input parameters (throttle opening, vehicle speed), and output performance indicators.

[0121] S3: Based on the calibration database, the GBDT (Gradient Boosting Tree) algorithm is used to iteratively optimize the shift line parameters and generate a calibration strategy adapted to high torque scenarios;

[0122] S301: Feature and Label Definitions:

[0123] The algorithm input features are defined as throttle opening, vehicle speed, engine torque, torque converter speed ratio, and gradient.

[0124] The output labels are defined as the vehicle speed offset at the optimal shift point and the torque correction coefficient;

[0125] S302: Iterative Optimization of GBDT Algorithm:

[0126] S30201: Set the algorithm hyperparameters: tree depth = 10, learning rate = 0.1, number of iterations = 500;

[0127] S30202: Using the impact and friction work in the database as loss functions, the model parameters are iteratively updated through gradient descent. With power performance (acceleration time), economy (energy consumption per 100 kilometers) and smoothness (subjective rating of impact) as optimization objectives, the shift point speed offset, torque correction coefficient and slope compensation coefficient are iteratively optimized.

[0128] S30203: Generate calibration strategies adapted to high torque scenarios, including shift lag / advance rules for different torque levels and dynamic control strategies for torque converter lock-up points.

[0129] The shifting rules are as follows: for torque level I (150-300Nm), the upshift advance is 2km / h; for torque level II (300-500Nm), the upshift lag is 3km / h; and for torque level III (>500Nm), the upshift lag is 5km / h.

[0130] S4: Real-vehicle multi-condition verification and performance comparison;

[0131] Through real-vehicle road tests, real-vehicle multi-condition verification was carried out, vehicle performance data was collected, the performance differences between the traditional shifting strategy and the calibration strategy of this invention were compared, and the comprehensive performance of the calibration strategy under real road conditions was verified.

[0132] S401: Experimental Design and Data Acquisition

[0133] Three typical test routes were selected, including urban congested sections (average speed <30km / h), high-speed cruising sections (speed 80-120km / h), and mountain climbing sections (gradient 5%-10%).

[0134] Install a vehicle data acquisition system to record vehicle performance data, including power performance indicators (0-100km / h acceleration time, accuracy ±0.1s, transmission system response time during gear shifting), economy indicators (energy consumption per 100km under various operating conditions), and smoothness indicators (objective data on gear shift shock and subjective driver rating on a 10-point scale, where 1 point indicates extremely strong shock and 10 points indicates no obvious shock).

[0135] Simultaneously, key data such as engine output torque, hydraulic torque converter transmission efficiency, and clutch slippage work are collected.

[0136] S402: Performance comparison and verification.

[0137] By comparing the performance differences between the traditional shifting strategy and the calibration strategy of this invention, the overall performance advantages of the strategy of this invention are verified.

[0138] The results show that the calibration strategy of the present invention reduces the vehicle's 0-100km / h acceleration time by about 12%, reduces energy consumption per 100km by 8.5%, and improves the subjective score of shift shock by more than 2 points, verifying the advantages of the strategy in improving the overall performance of the vehicle.

[0139] S5: Based on real vehicle verification results, the shift line parameters are corrected in real time through the Kalman filter algorithm, and the calibration strategy is dynamically adjusted to achieve a dynamic balance between power and economy under complex road conditions.

[0140] S501: Establish the state-space model:

[0141] Define state vector ,in: This is the vehicle speed offset at the gear shift point. This is the torque correction factor;

[0142] Define observation vector ,in Impact level;

[0143] S502: Kalman filter recursive calculation:

[0144] Prediction steps:

[0145] (2)

[0146] (3)

[0147] Update steps:

[0148] (4)

[0149] (5)

[0150] (6)

[0151] In equations (2)-(6):

[0152] These are discrete sampling times, corresponding to the real-time control cycle of the vehicle's TCU (e.g., one sampling step every 10ms).

[0153] This refers to the previous sampling time.

[0154] For prior predictions, only use The optimal result at time 1, for The predicted values ​​made at any given time were not incorporated. New observational data at any given time;

[0155] for The state prior prediction value at each moment, the predicted vehicle speed offset at the shift point, and the torque correction factor;

[0156] This is the state transition matrix;

[0157] for The posterior optimal value of the state at any given time, and the shift parameters finally determined in the previous control cycle;

[0158] To control the input matrix;

[0159] for The real-time operating condition inputs at any given moment are, in this invention, operating condition input parameters such as throttle opening, gradient, and real-time engine torque;

[0160] for The prior estimate of the covariance matrix at time t;

[0161] for The posterior estimated covariance matrix at time t;

[0162] State transition matrix The transpose of the matrix;

[0163] The process noise covariance matrix;

[0164] for Kalman gain at time step;

[0165] The observation matrix;

[0166] Observation matrix The transpose of the matrix;

[0167] To observe the noise covariance matrix;

[0168] for The posterior optimal value of the state at time 1;

[0169] for The measured observation vector at time;

[0170] The theoretical observed values, theoretical impact, and theoretical transmission efficiency are calculated based on the shift parameters predicted a priori.

[0171] for The posterior estimated covariance matrix at time t;

[0172] It is the identity matrix;

[0173] S503: Dynamic Adjustment Strategy

[0174] The shift line parameters are adjusted in real time based on the filtered output results. When heavy-load climbing conditions are detected (torque > set threshold and slope > 5°), the torque correction factor is increased and upshifting is delayed to maintain power, thereby achieving a dynamic balance between power and economy under complex road conditions.

[0175] S6: Write the optimized calibration strategy into the transmission control unit and conduct durability tests to verify the stability and reliability of the calibration strategy under long-term high torque conditions.

[0176] S601: TCU software integration;

[0177] The optimized shift line parameters, correction factors, and control logic are written into the TCU's Flash memory, and the parameter interface is described using A2L files to facilitate subsequent calibration and updates.

[0178] S602: Durability test verification:

[0179] Conduct road durability tests with a cumulative mileage of ≥10,000 km, covering scenarios such as high-speed ring roads, reinforced bad roads, and mountain roads; check the impact resistance and skid friction performance indicators every 1,000 km to confirm that there are no deviations or performance degradation;

[0180] After the test, the full-cycle operation data recorded by the TCU was analyzed to verify the stability and reliability of the calibration strategy under long-term high torque conditions.

[0181] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0182] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A calibration method for shift lines and shift strategies of high-torque vehicles, characterized in that: The method includes the following steps: S1: Construct a multi-objective optimization model that integrates the high torque characteristics of the engine, and design a dynamic shift line; S2: Build a bench test system to simulate high torque conditions, collect standardized transmission system operating data, and establish a calibration foundation database; S3: Based on the calibration database, the GBDT algorithm is used to iteratively optimize the shift line parameters and generate a calibration strategy adapted to high torque scenarios; S4: Real-vehicle multi-condition verification and performance comparison; S5: Based on real vehicle verification results, the shift line parameters are corrected in real time through the Kalman filter algorithm, and the calibration strategy is dynamically adjusted to achieve a dynamic balance between power and economy under complex road conditions. S6: Write the optimized calibration strategy into the transmission control unit and conduct durability tests to verify the stability and reliability of the calibration strategy under long-term high torque conditions.

2. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 1, characterized in that: S1 includes the following steps: S101: Determine the optimization objective and constraints; The optimization objectives are to maximize the efficiency of the transmission system, minimize the shift shock, and minimize the clutch slippage work. The constraints include the engine's maximum torque output range, the hydraulic torque converter's high-efficiency range, the pump wheel to turbine speed ratio range, and the clutch slippage work threshold. S102: Establish a multi-objective optimization mathematical model; S103: Design dynamic correction factor.

3. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 2, characterized in that: S102 includes the following steps: S10201: Constructing a multi-objective function using the weighted summation method: (1) In formula (1): This represents the comprehensive evaluation function value for multi-objective optimization. For the efficiency of the hydraulic torque converter; Normalized impact; To normalize the gliding friction work; All represent weighting coefficients; S10202: Establish a two-dimensional matrix of throttle opening and vehicle speed as the basic shift line. Within the range of 0%-100% throttle opening, divide the intervals into 5% intervals. Each interval corresponds to the vehicle speed threshold for upshifting and downshifting.

4. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 2, characterized in that: S103 includes the following steps: S10301: Designed with a large torque correction factor, it dynamically adjusts the shift point based on the ratio of the engine's real-time torque to its rated torque. When this ratio is greater than 1.2, the upshift speed is delayed by 5%-10%. S10302: Design a slope compensation coefficient correction factor. Obtain slope information through vehicle tilt sensor, establish a slope-shift offset mapping table, and complete the compensation adjustment of shift point based on slope sensor data to correct upshift speed in real time.

5. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 4, characterized in that: S2 includes the following steps: S201: Set up a bench test platform; S202: Simulates high torque conditions and collects data; S203: Data Processing and Database Construction.

6. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 5, characterized in that: S3 includes the following steps: S301: Feature and Label Definitions: The algorithm input features are defined as throttle opening, vehicle speed, engine torque, torque converter speed ratio, and gradient. The output labels are defined as the vehicle speed offset at the optimal shift point and the torque correction coefficient; S302: Iterative Optimization of GBDT Algorithm: S30201: Set algorithm hyperparameters; S30202: Using the impact and friction work in the database as loss functions, the model parameters are iteratively updated using the gradient descent method. With power performance, economy and smoothness as optimization objectives, the shift point speed offset, torque correction coefficient and slope compensation coefficient are iteratively optimized. S30203: Generate calibration strategies adapted to high torque scenarios, including shift lag / advance rules for different torque levels and dynamic control strategies for torque converter lock-up points.

7. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 6, characterized in that: S4 includes the following steps: S401: Experimental Design and Data Acquisition Three types of typical test routes were selected, including congested urban roads, highway cruising roads, and mountain climbing roads. Install a vehicle data acquisition system to record vehicle performance data, including power performance, economy performance, and ride comfort performance. Simultaneously, data on engine output torque, hydraulic torque converter transmission efficiency, and clutch slippage work are collected. S402: Performance comparison and verification.

8. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 7, characterized in that: S5 includes the following steps: S501: Establish the state-space model: Define state vector ,in: This is the vehicle speed offset at the gear shift point. This is the torque correction factor; Define observation vector ,in Impact level; S502: Kalman filter recursive calculation: Prediction steps: (2) (3) Update steps: (4) (5) (6) In equations (2)-(6): For discrete sampling times; This refers to the previous sampling time. These are prior predictions; for The prior state prediction at time 1; This is the state transition matrix; for The posterior optimal value of the state at time 1; To control the input matrix; for Real-time operating condition input at any given moment; for The prior estimate of the covariance matrix at time t; for The posterior estimated covariance matrix at time t; State transition matrix The transpose of the matrix; The process noise covariance matrix; for Kalman gain at time step; The observation matrix; Observation matrix The transpose of the matrix; To observe the noise covariance matrix; for The posterior optimal value of the state at time 1; for The measured observation vector at time; The theoretical observed values ​​are calculated based on the shift parameters predicted a priori. for The posterior estimated covariance matrix at time t; It is the identity matrix; S503: Dynamic Adjustment Strategy The shift line parameters are adjusted in real time based on the filtered output results. When heavy-load climbing conditions are detected, the torque correction factor is increased and upshifting is delayed to maintain power.

9. The calibration method for a high-torque vehicle shift line and shift strategy according to claim 8, characterized in that: S6 includes the following steps: S601: TCU software integration; S602: Durability test verification: Conduct road durability tests with a cumulative mileage of ≥10,000 km, covering scenarios such as high-speed ring roads, reinforced bad roads, and mountain roads; check the impact resistance and skid friction performance indicators every 1,000 km to confirm that there are no deviations or performance degradation; After the test, the full-cycle operation data recorded by the TCU was analyzed to verify the stability and reliability of the calibration strategy under long-term high torque conditions.

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