A mine vehicle composite braking cooperative control method based on multi-parameter sensing

Abstract

The application discloses a mine vehicle composite brake cooperative control method based on multi-parameter sensing, and relates to the technical field of mine vehicle control. The application comprises the following steps: constructing a multi-parameter sensing matrix containing the brake temperature, brake oil pressure, motor reverse drag torque, battery SOC and motor temperature; calculating the gradual exiting coefficient of the electric feedback braking force based on the sliding mode variable structure control algorithm, and combining the hydraulic brake gap pre-compensation mechanism to match the rise of the hydraulic braking force and the drop of the electric braking force; executing the torque closed-loop monitoring; establishing the brake system health file based on the brake event characteristic data to predict the friction plate wear and hydraulic leakage risk. The application realizes the smooth alternation of the electric feedback braking and the hydraulic braking through the dynamic sliding mode control and the pre-compensation cooperation, improves the driving smoothness under the heavy load downhill working condition, and provides the predictive maintenance basis.

Description

Technical Field

[0001] The invention belongs to the field of mining vehicle control technology, and in particular relates to a composite braking coordinated control method for mining vehicles based on multi-parameter sensing. Background Technology

[0002] Mining vehicles, especially large open-pit electric wheel dump trucks, typically employ a composite braking system, combining both electro-regenerative braking and hydraulic braking. Electro-regenerative braking utilizes the reverse drag characteristic of the drive motor to convert the vehicle's kinetic energy into electrical energy, which is then fed back to the battery pack, generating a reverse torque for deceleration. Hydraulic braking, similar to conventional vehicles, uses hydraulic pressure from the master cylinder to drive the brake calipers, causing frictional braking torque between the brake pads and discs. In this composite braking system, the vehicle control unit (VCU) dynamically allocates the ratio of the two braking forces based on the vehicle's condition and the driver's braking request.

[0003] The current mainstream composite braking control strategy for mining vehicles generally adopts the principle of prioritizing electric braking. That is, when the driver requests braking, the VCU prioritizes the use of regenerative braking to meet the braking force demand. Only when the battery state of charge is too high, the motor temperature is too high, or the vehicle speed is below a certain threshold, will the hydraulic braking system be instructed to intervene to supplement the remaining braking force. This strategy works well on smooth roads or under light load conditions. The intervention of hydraulic braking usually adopts a threshold triggering method. For example, when the battery state of charge exceeds the set upper limit or the motor temperature exceeds the limit value, the VCU reduces the regenerative braking force at a fixed slope, and at the same time sends a target pressure command to the hydraulic braking system, requesting it to fill the braking force gap.

[0004] However, the aforementioned existing technologies reveal a significant problem in practical applications: under conditions requiring substantial deceleration, such as sharp bends or passing other vehicles after a heavy-load downhill descent, the electro-regenerative braking system often approaches its capacity limit due to prolonged high-load operation (e.g., the motor or battery system is in a high-temperature protection state). If the driver presses the brake pedal deeply to request greater braking force, the VCU determines that the electric braking force is insufficient and instructs the hydraulic braking system to quickly assume the remaining braking force. However, the hydraulic braking system has an inherent mechanical response delay from receiving the command to the friction pads actually pressing against the brake disc and establishing effective braking force (including the time for filling the lines with oil and eliminating the gap between the friction pads and the brake disc). This delay causes the hydraulic braking force to not be fully established within the time window when the electro-regenerative braking force has already begun to decrease or withdraw according to the threshold strategy, resulting in a brief drop in the actual total braking force. Furthermore, when the hydraulic braking force is established with a lag, its pressure rise is often too rapid, making it difficult to match the decrease curve of the electro-regenerative braking force, ultimately resulting in a stepped jump in braking force. Such sudden changes in braking force can cause longitudinal impact on the vehicle under heavy load downhill conditions, reducing driving smoothness and, in severe cases, potentially leading to momentary wheel lock-up or slippage, affecting vehicle stability. Therefore, the following solutions are proposed to address these issues. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-parameter sensing-based composite braking coordinated control method for mining vehicles. By using dynamic sliding mode variable structure control, the method achieves the gradual withdrawal of electro-regenerative braking force. Combined with a hydraulic braking gap pre-compensation mechanism, the method matches the rise of hydraulic braking force with the fall of electro-braking force, achieving a smooth alternation of the two braking forces and solving the problem of braking force jump in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0007] This invention relates to a multi-parameter sensing-based composite braking coordinated control method for mining vehicles, comprising the following steps:

[0008] Step S1: Construct a multi-dimensional sensing matrix, the elements of which include brake friction pad temperature, brake master cylinder oil pressure, motor reverse torque, battery state of charge, motor temperature, vehicle speed and longitudinal acceleration.

[0009] Step S2: Calculate the total braking force demand requested by the driver based on the brake pedal displacement and vehicle speed;

[0010] Step S3: Evaluate the maximum available braking force for regenerative braking based on the battery state of charge and motor temperature;

[0011] Step S4: Introduce the brake thermal inertia weighting factor, calculate the electro-regenerative braking force intervention coefficient using the dynamic sliding mode variable structure control algorithm, and allocate the actual electro-regenerative braking force accordingly. The sliding mode surface function and control law satisfy the following formula:

[0012]

[0013]

[0014] In the formula, It is a sliding surface; The maximum braking force available instantaneously during regenerative braking; To provide the desired regenerative braking force; , , All are control gain constants; The weighting factor for the thermal inertia of the brake; The rate of change of the regenerative braking force intervention coefficient; It is a saturation function; Boundary layer thickness;

[0015] Step S5: Calculate the target braking force that the hydraulic braking system should bear based on the difference between the total braking force demand and the allocated electro-regenerative braking force, and establish a dynamic response prediction model for hydraulic braking force to generate a hydraulic braking gap pre-compensation command so that the rate of increase of hydraulic braking pressure is proportional to the absolute value of the rate of change of the electro-regenerative braking intervention coefficient.

[0016] Step S6: Send the electro-regenerative braking force distribution coefficient to the motor controller, send the target hydraulic braking force command to the brake electronic control unit, and execute compound braking;

[0017] Step S7: Collect the brake thermal load characteristics, regenerative braking participation characteristics, hydraulic system response characteristics, and motor and battery characteristics for each braking event, store them in the braking system health record table, and predict the remaining life of the friction pads and the leakage risk of the hydraulic system based on the sliding window linear regression algorithm.

[0018] Furthermore, in step S2, the total braking force requirement is calculated. The formula is:

[0019]

[0020] In the formula, This is the pedal displacement-braking force conversion coefficient; This refers to the displacement of the brake pedal; This is the vehicle speed correction factor; For vehicle speed; This refers to the vehicle's maximum design speed. The total mass of the vehicle; This is the acceleration due to gravity.

[0021] Furthermore, the method for evaluating the instantaneous maximum braking force of the regenerative braking in step S3 is as follows: calculate the maximum braking force limited by the battery state of charge and the maximum braking force limited by the motor temperature respectively, and take the minimum value between the two and the rated reverse drag braking force constant of the motor.

[0022] Furthermore, the brake thermal inertia weighting factor is calculated based on the brake temperature and its rate of change, and its value range is limited to a closed interval. The larger the value, the more severe the brake thermal load.

[0023] Furthermore, in step S5, the hydraulic braking force dynamic response prediction model incorporates the time constants for filling the brake line with oil and eliminating the gap between the friction pad and the brake disc, in order to predict the hydraulic braking force after a preset time interval.

[0024] Furthermore, the hydraulic brake clearance pre-compensation includes: sending a pre-pressurization command to the brake electronic control unit before the regenerative braking force intervention coefficient begins to decrease, so that the brake caliper piston eliminates the initial clearance between the brake disc and the brake cylinder; when the regenerative braking force intervention coefficient decreases, controlling the rate of increase of the hydraulic brake pressure to be proportional to the absolute value of the rate of change of the regenerative braking force intervention coefficient.

[0025] Furthermore, after step S6, torque closed-loop monitoring is also included: the actual output total braking force is calculated based on the collected motor reverse drag torque and brake master cylinder oil pressure, the torque tracking error is calculated, and when the torque tracking error exceeds the maximum allowable error for a preset number of consecutive sampling periods, it is determined to be a compound braking control misalignment and switched to safety mode.

[0026] Furthermore, the brake thermal load characteristics include peak temperature, high temperature duration, and temperature rise integral; the regenerative braking participation characteristics include total power contribution from electric braking and average intervention coefficient of electric braking; the hydraulic system response characteristics include response time and peak brake oil pressure fluctuation rate; and the motor and battery characteristics include peak motor temperature and battery state of charge change.

[0027] Furthermore, the method for predicting the remaining life of the friction pad is as follows: the cumulative wear volume of the friction pad is used as the prediction target, and its increment satisfies an exponential relationship with the total energy absorbed during the braking process and the average brake temperature, including the wear coefficient and the temperature acceleration factor; the wear coefficient and the temperature acceleration factor are identified online using the least squares method through a preset number of recent braking records in the health record table, and an early warning is issued when the cumulative predicted wear amount reaches a preset threshold of the total available wear amount.

[0028] Furthermore, the method for predicting the leakage risk of the hydraulic system is as follows: monitor the changing trend of the hydraulic system response time in the health record table. When the response time increases monotonically in a preset number of consecutive braking events and the cumulative increment exceeds a preset percentage of the nominal value, it is determined that there is a leakage risk and a level two warning is issued.

[0029] The present invention has the following beneficial effects:

[0030] This invention achieves gradual withdrawal of regenerative braking force through dynamic sliding mode variable structure control, combined with a hydraulic brake gap pre-compensation mechanism, enabling smooth alternation of the two braking forces during the transition phase, thus improving driving smoothness. A real-time braking capacity evaluation model based on multiple parameters such as brake temperature, oil pressure, and motor reverse torque can adapt to changes in braking demand under complex operating conditions. The establishment of a braking system health record and data-driven prediction provide early warning of friction pad wear and hydraulic system leakage, helping to reduce the risk of unplanned downtime. A torque closed-loop monitoring and fault-tolerant switching mechanism enhances the operational reliability of the composite braking system.

[0031] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart illustrating a multi-parameter sensing-based composite braking coordinated control method for mining vehicles according to the present invention. Detailed Implementation

[0034] 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.

[0035] Please see Figure 1 As shown, this invention is a composite braking coordinated control method for mining vehicles based on multi-parameter sensing. The control method includes the following steps:

[0036] Step S1: Construct a multi-dimensional sensing matrix. The elements of the sensing matrix include brake friction pad temperature, brake master cylinder oil pressure, motor reverse torque, battery state of charge, motor temperature, vehicle speed, and longitudinal acceleration.

[0037] Step S2: Calculate the total braking force demand requested by the driver based on the brake pedal displacement and vehicle speed;

[0038] Step S3: Evaluate the maximum available braking force for regenerative braking based on the battery state of charge and motor temperature;

[0039] Step S4: Introduce the brake thermal inertia weighting factor, calculate the electro-regenerative braking force intervention coefficient using the dynamic sliding mode variable structure control algorithm, and allocate the actual electro-regenerative braking force accordingly. The sliding mode surface function and control law satisfy the following formula:

[0040]

[0041]

[0042] In the formula, It is a sliding surface; The maximum braking force available instantaneously during regenerative braking; To provide the desired regenerative braking force; , , All are control gain constants; The weighting factor for the thermal inertia of the brake; The rate of change of the regenerative braking force intervention coefficient; It is a saturation function; Boundary layer thickness;

[0043] Step S5: Calculate the target braking force that the hydraulic braking system should bear based on the difference between the total braking force demand and the allocated electro-regenerative braking force, and establish a dynamic response prediction model for hydraulic braking force to generate a hydraulic braking gap pre-compensation command so that the rate of increase of hydraulic braking pressure is proportional to the absolute value of the rate of change of the electro-regenerative braking intervention coefficient.

[0044] Step S6: Send the electro-regenerative braking force distribution coefficient to the motor controller, send the target hydraulic braking force command to the brake electronic control unit, and execute compound braking;

[0045] Step S7: Collect the brake thermal load characteristics, regenerative braking participation characteristics, hydraulic system response characteristics, and motor and battery characteristics for each braking event, store them in the braking system health record table, and predict the remaining life of the friction pads and the leakage risk of the hydraulic system based on the sliding window linear regression algorithm.

[0046] In step S2, the total braking force requirement is calculated. The formula is:

[0047]

[0048] In the formula, This is the pedal displacement-braking force conversion coefficient; This refers to the displacement of the brake pedal; This is the vehicle speed correction factor; For vehicle speed; This refers to the vehicle's maximum design speed. The total mass of the vehicle; This is the acceleration due to gravity.

[0049] The method for evaluating the instantaneous maximum braking force of regenerative braking in step S3 is as follows: calculate the maximum braking force limited by the battery state of charge and the maximum braking force limited by the motor temperature, and take the minimum value between the two and the rated reverse drag braking force constant of the motor.

[0050] The brake thermal inertia weighting factor is calculated based on the brake temperature and its rate of change. The value range is limited to a closed interval, and the larger the value, the more severe the brake thermal load.

[0051] In step S5, the hydraulic braking force dynamic response prediction model introduces the time constants for filling the brake line with oil and eliminating the gap between the friction pad and the brake disc, which are used to predict the hydraulic braking force after a preset time interval.

[0052] Hydraulic brake clearance pre-compensation includes: sending a pre-pressurization command to the brake electronic control unit before the regenerative braking force intervention coefficient begins to decrease, so that the brake caliper piston eliminates the initial clearance between the brake disc and the brake cylinder; when the regenerative braking force intervention coefficient decreases, controlling the rate of increase of hydraulic brake pressure to be proportional to the absolute value of the rate of change of the regenerative braking force intervention coefficient.

[0053] Step S6 is followed by torque closed-loop monitoring: the actual total braking force is calculated based on the collected motor reverse drag torque and brake master cylinder oil pressure, and the torque tracking error is calculated. When the torque tracking error exceeds the maximum allowable error for a preset number of consecutive sampling periods, it is determined to be a compound braking control misalignment and the system is switched to safe mode.

[0054] Brake thermal load characteristics include peak temperature, high temperature duration, and temperature rise integral; regenerative braking participation characteristics include total power contribution from electric braking and average intervention coefficient of electric braking; hydraulic system response characteristics include response time and peak brake oil pressure fluctuation rate; motor and battery characteristics include peak motor temperature and battery state of charge change.

[0055] The method for predicting the remaining life of the friction pads is as follows: the cumulative wear volume of the friction pads is used as the prediction target, and its increment satisfies the exponential relationship between the total energy absorbed during the braking process and the average brake temperature, which includes the wear coefficient and the temperature acceleration factor; the wear coefficient and the temperature acceleration factor are identified online using the least squares method through a preset number of recent braking records in the health record table, and an early warning is issued when the cumulative predicted wear amount reaches the preset threshold of the total available wear amount.

[0056] The method for predicting the risk of leakage in a hydraulic system is as follows: monitor the trend of the response time of the hydraulic system in the health record table. When the response time increases monotonically in a series of braking events with a cumulative increment exceeding a preset percentage of the nominal value, a leakage risk is determined and a level-two warning is issued.

[0057] The specific application of this embodiment is as follows:

[0058] Step S1: System initialization and construction of multi-parameter sensing matrix

[0059] The following steps are performed based on the existing vehicle controller (VCU), braking system electronic control unit (BECU), battery management system (BMS), motor controller (MCU), and various sensor networks of the mining vehicle.

[0060] After the mining vehicle completes its power-on self-test, the VCU executes the initialization of the composite braking coordination control program. The VCU first establishes synchronous communication with the BECU, BMS, and MCU via the CAN bus and allocates a dynamic data storage area. The VCU then constructs a multi-dimensional sensing matrix. This matrix is ​​used to characterize the dynamic state of the braking system in real time. The definition of this matrix is ​​as follows:

[0061]

[0062] In the formula, The current sampling time is set to a sampling period of 10ms; It is the weighted average of the temperature data collected by the four brake friction pad surface sensors (left front, right front, left rear, and right rear). The real-time hydraulic pressure is measured by the brake master cylinder oil pressure sensor. This is the actual value of the motor's reverse torque fed back from the motor controller; The battery is in its state of charge. This refers to the temperature of the motor stator windings. The instantaneous vehicle speed is calculated by the wheel speed sensor; The longitudinal acceleration of the vehicle is measured by an accelerometer. The VCU refreshes this sensing matrix cyclically every 20ms and stores it in non-volatile memory, forming a real-time state snapshot.

[0063] Step S2: Braking Intent Recognition and Initial Braking Force Requirement Calculation

[0064] When the driver presses the brake pedal, the VCU collects the signal from the brake pedal displacement sensor, which is recorded as follows: Its range is 0-100%. The VCU combines the current vehicle speed. and vehicle total mass Calculate the total braking force demand requested by the driver. To prevent inconsistent driving experience caused by the same braking force demand at different vehicle speeds due to a single pedal position, a braking force demand model based on vehicle speed correction is adopted:

[0065]

[0066] In the formula, The pedal displacement-braking force conversion coefficient is obtained through bench calibration. This is a speed correction factor, ranging from 0.1 to 0.3, used to simulate the physical laws that require greater deceleration at high speeds; This refers to the vehicle's maximum design speed. This is due to gravitational acceleration. The VCU will use this total braking force. This serves as the target value for subsequent braking force distribution.

[0067] Step S3: Assessment of the instantaneous availability of regenerative braking

[0068] VCU from the perception matrix Extracting battery SOC and motor temperature As input, assess the maximum braking force that the regenerative braking system can safely and stably provide at the current moment. The evaluation adopts the minimum principle under multidimensional constraints:

[0069]

[0070] In the formula, This is the rated reverse braking force constant of the motor; The maximum braking force limited by battery SOC is calculated using the following formula:

[0071]

[0072] In the formula, In order to be in The state of charge of the battery at any given time; This is the lower limit threshold of battery SOC; This represents the upper limit threshold of battery SOC; This represents the width of the SOC variation range.

[0073] The maximum braking force, limited by motor temperature, is calculated using the following formula:

[0074]

[0075] In the formula, In order to be in The temperature of the motor stator winding at any given time; This is the lower limit threshold for motor temperature; This is the upper limit threshold for motor temperature; This refers to the width of the temperature variation range;

[0076] Step S4: Predictive exit of electro-regenerative braking under dynamic sliding mode variable structure control

[0077] VCU not only assesses the current Furthermore, it predicts its future trends. It defines the rate of decay of regenerative braking capability. Through history The data is obtained through differential calculation. To achieve accurate sensing of the brake's thermal state to drive the deactivation mechanism, a brake thermal inertia weighting factor is introduced here. Its value is based on the brake temperature in step S1. and its rate of change calculate:

[0078]

[0079] In the formula, In order to be in The brake thermal inertia weighting factor at time t, with a value range of [0,1]. The larger the value, the more severe the brake thermal load, and the braking capacity will soon decrease rapidly. This is the current sampling time; This refers to the maximum permissible operating temperature of the brake, such as 450℃. The nominal temperature rise rate is, for example, 5℃ / s; the VCU uses a dynamic sliding mode variable structure control algorithm to calculate the real-time intervention coefficient of the regenerative braking. This algorithm introduces a sliding surface function. To ensure Smooth changes, avoiding abrupt changes:

[0080] Define the sliding surface In the formula, The VCU expects the regenerative braking system to provide the braking force. Let be the sliding mode approach coefficient, with a value of 2.5. The sliding mode variable structure control law is designed as follows, used for calculation. rate of change :

[0081]

[0082] In the formula, and All are positive control gain constants. , ; This is a saturation function used to eliminate chattering; The boundary layer thickness is set to 0.05.

[0083] VCU uses numerical integration The real-time regenerative braking force intervention coefficient is obtained and limited within the range of [0,1]. In the formula, Let be the integral variable, representing time.

[0084] The final actual distribution of regenerative braking force for:

[0085]

[0086] The core function of this sliding mode controller is: when... Increase or During rapid decay, As the value deviates from zero, the controller calculates a gradually decreasing value at an optimized, non-abrupt rate. This allows for a gradual withdrawal of the electro-regenerative braking force; this gradual withdrawal curve provides a precise time window for subsequent hydraulic braking intervention.

[0087] Step S5: Coordination of Hydraulic Braking Clearance Pre-compensation and Force Distribution

[0088] VCU is based on the established Total demand Calculate the target braking force that the hydraulic braking system should bear. .

[0089] However, hydraulic braking force The response exhibits a first-order hysteresis characteristic. To eliminate this hysteresis, it is necessary to achieve... Precise synchronization of the gradual withdrawal process triggers the hydraulic brake clearance pre-compensation mechanism in the VCU.

[0090] The VCU obtains the actual hydraulic braking force from the previous moment from the sensing matrix. This value is measured by the brake fluid pressure sensor. Through relational formulas Indirect calculation, where, In order to be in The hydraulic pressure of the master cylinder at any given moment; This refers to the piston area of ​​the brake caliper. The friction coefficient of the friction plate; The effective braking radius.

[0091] The VCU establishes a dynamic response prediction model for hydraulic braking force, which considers the time constants for oil filling of the brake lines and elimination of the gap between the friction pads and the brake disc. :

[0092]

[0093]

[0094] In the formula, For the predicted future Hydraulic braking force after a certain time; To predict the time step, we set it to 100ms; In order to be in The actual hydraulic braking force at any given moment; The time constant of the hydraulic system; This is the target pressure command currently being sent from the VCU to the BECU.

[0095] The core cooperative control logic of the VCU is: to solve for the optimal solution within a prediction-correction loop. This ensures that at the next moment, the actual total braking force output... Capable of accurately tracking driver needs This is achieved through a proportional-integral-predictive (PIP) controller, whose output is... This includes not only the current demand difference but also a pre-compensation amount to eliminate future deviations. Specifically, the VCU instructs the BECU to immediately perform a pre-boost action, rapidly pushing the brake caliper piston towards the brake disc to eliminate the initial gap between the friction pads and the brake disc, but no substantial braking pressure is established during this stage. When regenerative braking... When the descent begins, the BECU... Precise control of the inlet valve allows the hydraulic braking pressure to rise smoothly from zero, with a controlled rate of increase. and It is directly proportional to the absolute value, that is:

[0096]

[0097] In the formula, In order to be in At time t, the first derivative of the brake master cylinder hydraulic pressure with respect to time; This is the synchronization ratio coefficient; In order to be in At what moment, the regenerative braking intervention coefficient The first derivative with respect to time; This is the maximum oil pressure of the system. In this way, a seamless back-to-back transition between the gradual reduction of electro-regenerative braking force and the gradual increase of hydraulic braking force is achieved.

[0098] Step S6: Composite braking execution and torque closed-loop monitoring

[0099] VCU will calculate The signal is sent to the MCU via the CAN bus, and the MCU uses this signal to control the inverter to generate the corresponding reverse torque; simultaneously... Convert to target pressure value The signal is sent to the BECU, which then drives the solenoid valve in the hydraulic control unit (HCU) to regulate the pressure. During execution, the VCU continuously acquires data from the sensing matrix at 10ms intervals. and And convert it into the actual total output braking force:

[0100]

[0101] In the formula, In order to be in The total braking force actually output by the vehicle at any given moment; In order to be in Actual value of motor reverse torque at any given moment; The speed ratio of the reducer; The tire's rolling radius; In order to be in The hydraulic pressure of the master cylinder at any given moment; This refers to the piston area of ​​the brake caliper. The friction coefficient of the friction plate; The effective braking radius is the distance from the center of the wheel to the point of application of the equivalent friction force on the brake disc.

[0102] VCU calculates torque tracking error ,like Exceeding the maximum permissible error for 10 consecutive sampling periods If the value is 5000N, it is determined that the compound braking control is out of control. The VCU immediately switches to the safety mode, sends a command to reduce the regenerative braking to zero, and the BECU establishes full hydraulic braking in an open-loop manner. At the same time, the instrument panel fault light is illuminated and the fault code is stored.

[0103] Step S7: Establishing and updating the braking system health record based on usage data

[0104] After each braking event, marked by the complete release of the brake pedal, the VCU extracts and stores features from all data of that braking process, forming a braking health record. The extracted features include:

[0105] Brake thermal load characteristics: peak temperature Temperature rise integral Duration of high temperature For example, the time when the temperature is above 300℃.

[0106] Regenerative braking participation characteristics: Electric braking contributes total power Average intervention coefficient of electric braking .

[0107] Hydraulic system response characteristics: From the moment the brake is applied... arrive Achieving 90% of the target response time Brake oil pressure peak fluctuation rate.

[0108] Motor and battery characteristics: Peak motor temperature during braking SOC change .

[0109] The VCU stores this feature data in a brake system health record table in non-volatile memory. This table is arranged chronologically and stores a maximum of 2000 braking records. The VCU runs a sliding window linear regression algorithm to predict the remaining life of the friction pads, based on the cumulative wear volume of the friction pads. For the prediction target. The increment and the total energy absorbed during the braking process and average brake temperature The relevant empirical formula is:

[0110]

[0111] In the formula, This represents the increase in wear volume of the friction pads during a single braking process; The wear coefficient; This represents the total energy absorbed by the braking system during a single braking process. It is a temperature acceleration factor; The average temperature of the brake during a single braking process; The ambient temperature.

[0112] VCU checks the health record for the 100 most recent braking records. , The wear and tear, as indicated by maintenance personnel, are identified online using the least squares method. and When the cumulative predicted wear reaches 90% of the total usable wear of the friction pads, the VCU issues a warning via the onboard display. Simultaneously, regarding the risk of hydraulic leakage, the VCU monitors the health record form. The trend, if If the brake master cylinder or pipeline shows a monotonically increasing trend in 50 consecutive braking events and the cumulative increase exceeds 20% of the nominal value, such as from 100ms to 120ms, it is determined that there is a risk of leakage or internal leakage in the brake master cylinder or pipeline, and a level two warning is issued to prompt maintenance.

[0113] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0114] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for coordinated braking control of mining vehicles based on multi-parameter sensing, characterized in that, The control method includes the following steps: Step S1: Construct a multi-dimensional sensing matrix, the elements of which include brake friction pad temperature, brake master cylinder oil pressure, motor reverse torque, battery state of charge, motor temperature, vehicle speed and longitudinal acceleration. Step S2: Calculate the total braking force demand requested by the driver based on the brake pedal displacement and vehicle speed; Step S3: Evaluate the maximum available braking force for regenerative braking based on the battery state of charge and motor temperature; Step S4: Introduce the brake thermal inertia weighting factor, calculate the electro-regenerative braking force intervention coefficient using the dynamic sliding mode variable structure control algorithm, and allocate the actual electro-regenerative braking force accordingly. The sliding mode surface function and control law satisfy the following formula: ； ； In the formula, It is a sliding surface; The maximum braking force available instantaneously during regenerative braking; To provide the desired regenerative braking force; , , All are control gain constants; The weighting factor for the thermal inertia of the brake; The rate of change of the regenerative braking force intervention coefficient; It is a saturation function; Boundary layer thickness; Step S5: Calculate the target braking force that the hydraulic braking system should bear based on the difference between the total braking force demand and the allocated electro-regenerative braking force, and establish a dynamic response prediction model for hydraulic braking force to generate a hydraulic braking gap pre-compensation command so that the rate of increase of hydraulic braking pressure is proportional to the absolute value of the rate of change of the electro-regenerative braking intervention coefficient. Step S6: Send the electro-regenerative braking force distribution coefficient to the motor controller, send the target hydraulic braking force command to the brake electronic control unit, and execute compound braking; Step S7: Collect the brake thermal load characteristics, regenerative braking participation characteristics, hydraulic system response characteristics, and motor and battery characteristics for each braking event, store them in the braking system health record table, and predict the remaining life of the friction pads and the leakage risk of the hydraulic system based on the sliding window linear regression algorithm.

2. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, In step S2, the total braking force requirement is calculated. The formula is: ； In the formula, This is the pedal displacement-braking force conversion coefficient; This refers to the displacement of the brake pedal; This is the vehicle speed correction factor; For vehicle speed; This refers to the vehicle's maximum design speed. The total mass of the vehicle; This is the acceleration due to gravity.

3. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, The method for evaluating the instantaneous maximum braking force of the regenerative braking in step S3 is as follows: calculate the maximum braking force limited by the battery state of charge and the maximum braking force limited by the motor temperature, and take the minimum value between the two and the rated reverse drag braking force constant of the motor.

4. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, The brake thermal inertia weighting factor is calculated based on the brake temperature and its rate of change, and its value range is limited to a closed interval. The larger the value, the more severe the brake thermal load.

5. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, In step S5, the hydraulic braking force dynamic response prediction model introduces the time constants for filling the brake line with oil and eliminating the gap between the friction pad and the brake disc, which are used to predict the hydraulic braking force after a preset time interval.

6. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 5, characterized in that, The hydraulic brake clearance pre-compensation includes: sending a pre-pressurization command to the brake electronic control unit before the regenerative braking force intervention coefficient begins to decrease, so that the brake caliper piston eliminates the initial clearance between the brake disc and the brake cylinder; when the regenerative braking force intervention coefficient decreases, controlling the rate of increase of the hydraulic brake pressure to be proportional to the absolute value of the rate of change of the regenerative braking force intervention coefficient.

7. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, Step S6 is followed by torque closed-loop monitoring: the actual total braking force is calculated based on the collected motor reverse drag torque and brake master cylinder oil pressure, and the torque tracking error is calculated. When the torque tracking error exceeds the maximum allowable error for a preset number of consecutive sampling periods, it is determined to be a compound braking control misalignment and the system is switched to safe mode.

8. The method for coordinated control of compound braking of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, The brake thermal load characteristics include peak temperature, high temperature duration, and temperature rise integral. The electro-regenerative braking participation characteristics include the total power contributed by the electric braking and the average intervention coefficient of the electric braking; the hydraulic system response characteristics include response time and peak fluctuation rate of braking oil pressure; the motor and battery characteristics include peak motor temperature and battery state of charge change.

9. The method for coordinated control of compound braking of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, The method for predicting the remaining life of the friction pad is as follows: the cumulative wear volume of the friction pad is used as the prediction target, and its increment satisfies the exponential relationship between the total energy absorbed during the braking process and the average brake temperature, which includes the wear coefficient and the temperature acceleration factor; the wear coefficient and the temperature acceleration factor are identified online using the least squares method through a preset number of recent braking records in the health record table, and an early warning is issued when the cumulative predicted wear amount reaches a preset threshold of the total available wear amount.

10. The method for coordinated braking control of mining vehicles based on multi-parameter sensing according to claim 1, characterized in that, The method for predicting the leakage risk of the hydraulic system is as follows: monitor the changing trend of the hydraulic system response time in the health record table. When the response time increases monotonically in a preset number of consecutive braking events and the cumulative increment exceeds a preset percentage of the nominal value, it is determined that there is a leakage risk and a level two warning is issued.

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