A wheel drive mining truck and a braking control system and method therefor

Abstract

The application discloses a wheel-side driving mine truck, a braking control system and method thereof, the wheel-side driving mine truck adopts middle and rear axle driving, hydraulic brakes are arranged corresponding to each wheel, driving motor assemblies are arranged corresponding to each middle and rear axle wheel, and a material mass detection mechanism is arranged, the braking control system and method analyze the braking mode of the mine truck according to the state of multiple control mechanisms of the mine truck, and mode calculation is carried out on the braking force demand in combination with the material mass change, so that the braking force demand result is more refined and accurate, and the braking impact is too large or the braking force is insufficient due to the braking force request deviation is avoided; the maximum ground braking force is estimated according to the vehicle speed and the load distribution under different material masses, and the maximum allowable braking torque of each wheel is obtained in combination with the allowable braking torque of the driving motor assembly and the hydraulic braking capacity, so that the tire is prevented from being locked due to the too large output braking torque; the braking torque is distributed on the premise that the battery is not overcharged and the low-speed electric braking motor is prevented from being reversed, the electric braking is given priority, and the maximum braking recovery energy is obtained.

Description

Technical Field

[0001] This invention relates to the field of new energy engineering machinery technology, and in particular to a wheel-side driven mining truck and its braking control system and method. Background Technology

[0002] With the accelerating electrification of construction machinery, electric mining trucks have become increasingly common in mines and aggregate yards. Compared to gasoline-powered trucks, electric mining trucks offer significant advantages: firstly, they feature electric pausing and braking, reducing tire and brake wear; secondly, they have lower maintenance costs, eliminating engine maintenance expenses; thirdly, they have lower energy consumption, especially under heavy loads, significantly reducing energy costs; and fourthly, they are quieter, improving driving comfort. Furthermore, with the implementation of the national dual-carbon strategy, the electrification of mining trucks is an inevitable trend.

[0003] Compared to centralized drive systems, the wheel-side drive technology of electric mining trucks offers more possibilities for dynamic control due to the independent controllability of each motor. Applying distributed drive technology to mining trucks enables coordinated control of drive wheel torque, reducing tire slippage and wear, and improving the overall power and economy of the machine.

[0004] As the main equipment for material transportation, mining trucks carry out earthwork operations in mines. A typical workflow is to load in a designated loading area, transport the truck to the unloading area after it is full, unload it, and then return to the loading area for the next loading-unloading cycle. Frequent braking is required during this process. For mining trucks with wheel-side drive, more braking energy can be recovered while meeting the braking force requirements by dynamically distributing the electric braking torque and hydraulic braking torque of each wheel.

[0005] Existing wheel-side drive braking force control schemes have proposed some composite braking control methods, but these methods are mainly for electric vehicles. Electric vehicles and mining trucks have different application scenarios, and their braking modes and influencing factors are also different. Therefore, the traditional electric vehicle wheel-side drive composite braking control method cannot be applied to electric mining trucks. Summary of the Invention

[0006] The purpose of this invention is to provide a wheel-side driven mining truck and its braking control system and method, which is applicable to various braking modes of electric mining trucks and can dynamically adjust the braking force distribution according to the braking force requirements, thereby recovering more braking energy while meeting the braking force requirements of electric mining trucks. The technical solution adopted by this invention is as follows.

[0007] On one hand, the present invention provides a wheel-side driven mining truck, comprising:

[0008] The hydraulic braking control system includes a hydraulic braking control unit and hydraulic brakes respectively installed for each wheel and controlled by the hydraulic braking control unit. The hydraulic brakes are used to output hydraulic braking torque to each corresponding wheel.

[0009] The drive motor assembly is provided for each wheel connected to the central axle and the rear axle, and is used to drive the corresponding wheel to rotate and output electric braking torque to the corresponding wheel.

[0010] An energy recovery unit, including a battery, is used to recover braking energy when the drive motor assembly outputs electric braking torque to the wheels;

[0011] The hopper operation unit is equipped with a material quality detection device;

[0012] The vehicle operation status detection unit is used to collect vehicle operation status information;

[0013] The main controller is used to receive material quality information output by the material quality detection device, and to control the electric braking torque output of each drive motor assembly according to braking requirements, the material quality information, the state of charge of the battery and the vehicle operating status information, and / or to control the hydraulic braking torque output of each hydraulic brake through the hydraulic braking control unit.

[0014] The wheel-side driven mining truck of the present invention adopts a wheel-side drive form with a central axle and a rear axle. By setting hydraulic brakes for each wheel and drive motor assemblies for each rear wheel, and collecting material quality information and vehicle operating status information, it can support the main controller to realize dynamic distribution of braking torque under different braking modes and material quality based on the collected information.

[0015] In a second aspect, the present invention provides a braking control system for the wheel-side driven mining truck described in the first aspect, wherein the vehicle operating status detection unit includes a vehicle speed sensor; the braking control system includes: a brake pedal, an emergency stop switch, a deceleration handle, an accelerator pedal, a gear shift handle, and the main controller.

[0016] The different opening degrees of the brake pedal correspond to different target accelerations. The emergency stop switch state is used to transmit an emergency braking request to the main controller. The retarder handle includes multiple gears, each gear corresponding to a set of target vehicle speeds and target braking accelerations.

[0017] The main controller is configured as follows:

[0018] The system receives material quality information output by the material quality detection device, vehicle speed information output by the vehicle speed sensor, opening information of the brake pedal and accelerator pedal, position information of the emergency stop switch, retarder handle and gear shift handle, output shaft speed and electric braking torque limit fed back by the drive motor assembly, and battery state of charge information.

[0019] Based on the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch, the retarder lever and the gear shift lever, and the material quality information, the braking force demand data is obtained by analysis.

[0020] Based on the output shaft speed, electric braking torque limit, and material mass information, the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft are analyzed and obtained.

[0021] Based on the vehicle speed information, battery state of charge information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque, the hydraulic braking torque and electric braking torque are allocated to each wheel.

[0022] Thirdly, the present invention provides a braking control method for the wheel-side driven mining truck described in the first aspect, comprising:

[0023] Acquire material quality information of the mining truck, vehicle speed information, brake pedal and accelerator pedal opening information, emergency stop switch and deceleration handle position information, output shaft speed and electric braking torque limit of the drive motor assembly, and battery charge status information.

[0024] Based on the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch and the retarder handle, and the material mass information, the braking force demand data is obtained through analysis.

[0025] Based on the output shaft speed, electric braking torque limit, and material mass information, the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft are analyzed and obtained.

[0026] Based on the vehicle speed information, battery state of charge information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque, the hydraulic braking torque and electric braking torque are allocated to each wheel.

[0027] Optionally, the braking force demand data is obtained by analyzing the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch and the retarder handle, and the material mass information, including:

[0028] Based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift lever and deceleration lever, the braking mode is determined. The braking modes include: emergency stop braking mode, service braking mode, deceleration braking mode, coasting braking mode and deceleration speed adjustment mode.

[0029] If the braking mode is slow speed adjustment mode, the braking force requirement is calculated based on the deviation between the target vehicle speed corresponding to the slow gear and the current vehicle speed, and the current material mass.

[0030] If the braking mode is other than the slow speed adjustment mode, the target braking acceleration is determined according to the opening of the brake pedal, the opening of the accelerator pedal or the position of the emergency stop switch, and the current braking acceleration is calculated according to the current vehicle speed. Then, the braking force requirement is calculated according to the deviation between the target braking acceleration and the current braking acceleration and the current material mass.

[0031] If the mining truck is in non-braking mode, the braking force requirement is 0.

[0032] Optionally, the retarder handle includes multiple retarder levels, with the target vehicle speed decreasing sequentially and the target braking acceleration increasing sequentially for each retarder level.

[0033] The step of determining the braking mode based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift lever, and retarder lever includes:

[0034] If the emergency stop switch is in the pressed position, the braking mode is the emergency stop braking mode, and the corresponding target braking acceleration is the maximum value;

[0035] If the brake pedal opening is greater than 0 degrees, the braking mode is the service braking mode, and the corresponding target braking acceleration is calculated based on the brake pedal opening.

[0036] If the slow-moving gear is greater than 0 and the current vehicle speed is less than a multiple of the target speed corresponding to the slow-moving gear, the braking mode is slow-moving speed adjustment mode; otherwise, it is determined whether the accelerator pedal opening is not greater than 0 or the gear shift lever is in N gear. If not, the mining truck is in non-braking mode; if so, the braking mode is coasting braking mode, and the corresponding target braking acceleration is the preset coasting braking acceleration.

[0037] In the above technical solution, the preferred setting factor for determining the slow-speed adjustment mode is 1.5 times.

[0038] Optionally, the step of calculating the braking force requirement based on the deviation between the target vehicle speed corresponding to the slow-moving gear and the current vehicle speed, and the current material mass, includes:

[0039] Calculate the deviation between the target speed and the current speed corresponding to the slow-moving gear;

[0040] Based on the rated load ratio range of the current material mass, query the preset material mass and PID parameter mapping table to determine the PID parameters for the current material mass used for vehicle speed closed-loop PID control.

[0041] The braking force requirement is calculated based on the deviation between the target vehicle speed and the current vehicle speed, as well as the determined PID parameters.

[0042] Optionally, the braking force requirement is calculated based on the deviation between the target vehicle speed and the current vehicle speed, as well as the determined PID parameters. The calculation formula is as follows:

[0043]

[0044] In the formula, k represents the execution cycle count of the closed-loop PID control, F1(k) is the braking force requirement of the kth control cycle in the slow speed regulation mode; Δv(k) and Δv(k-1) are the deviations between the target vehicle speed and the current vehicle speed in the kth and k-1th control cycles, respectively; P1, I1, and D1 are the control parameters of the vehicle speed closed-loop PID control.

[0045] Optionally, the step of calculating the braking force requirement based on the deviation between the target braking acceleration and the current braking acceleration, and the current material mass, includes:

[0046] Calculate the current braking acceleration based on the current vehicle speed;

[0047] Calculate the deviation between the target braking acceleration and the current braking acceleration;

[0048] Based on the rated load ratio range of the current material mass, query the preset material mass and PID parameter mapping table to determine the PID parameters for the current material mass used for closed-loop PID control of braking acceleration.

[0049] The braking force requirement is calculated based on the deviation between the target braking acceleration and the current braking acceleration, as well as the determined PID parameters.

[0050] Optionally, the braking force requirement is calculated based on the deviation between the target braking acceleration and the current braking acceleration, as well as the determined PID parameters. The calculation formula is as follows:

[0051]

[0052] In the formula, k represents the execution cycle count of the closed-loop PID control, F1(k) is the braking force requirement in the k-th control cycle under emergency braking mode, service braking mode, slow braking mode or coasting braking mode; △a(k) and △a(k-1) are the deviations between the target braking acceleration and the current braking acceleration in the k-th and k-1-th control cycles, respectively; P2, I2 and D2 are the control parameters of the closed-loop PID control of braking acceleration.

[0053] Optionally, the rated load percentage range includes [0, 30%], (30%, 60%], (60%, 90%], and above 90%;

[0054] In the preset material mass and PID parameter mapping table, the PID parameters are set to satisfy the following condition: the greater the material mass, the faster the braking force demand response when using the corresponding PID parameters for closed-loop PID control.

[0055] Optionally, in the preset material mass to PID parameter mapping table, the PID parameters are set to satisfy the following: the greater the proportion of material mass to rated load, the larger the values ​​of parameters P and I in the PID parameters, while the value of parameter D remains unchanged. This method of setting PID parameters achieves the goal that the greater the material mass, the faster the braking force demand response when using the corresponding PID parameters for closed-loop PID control.

[0056] Optionally, in the preset material mass to PID parameter mapping table, the mapping relationship between the material mass as a percentage of the rated load and the vehicle speed closed-loop PID control parameters is as follows:

[0057] <![CDATA[P1]]> <![CDATA[I1]]> <![CDATA[D1]]> 0-30% of the load 50 4 2 30% to 60% of the rated load 65 5 2 60%–90% of the rated load 75 5.5 2 >90% of the load 80 6 2

[0058] Optionally, in the preset material mass to PID parameter mapping table, the mapping relationship between the material mass as a percentage of the rated load and the braking acceleration closed-loop PID control parameters is as follows:

[0059] <![CDATA[P2]]> <![CDATA[I2]]> <![CDATA[D2]]> 0-30% of the load 4 0.5 0.2 30% to 60% of the quota 4.6 0.8 0.2 60%–90% of the rated load 5.2 1 0.2 >90% of the load 6 1.2 0.2

[0060] The above parameters can be selected based on actual vehicle testing, calibration, and adjustment.

[0061] Optionally, the step of analyzing and obtaining the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft based on the output shaft speed, electric braking torque limit, and material mass information includes:

[0062] Calculate the slip ratio of each drive wheel based on the current vehicle speed and wheel angular velocity;

[0063] The braking force coefficient of each drive wheel is determined based on the slip ratio of each drive wheel;

[0064] For the left and right wheels on the same axle connected to each center axle and rear axle, the smaller braking force coefficient is taken as the wheel braking coefficient of that axle.

[0065] The smaller of the braking coefficients of the center axle and the rear axle is used as the braking force coefficient of the driven wheel on the front axle.

[0066] Calculate the vertical load on each axis based on the material mass;

[0067] Calculate the maximum ground braking force of the wheels connected to each axle based on the vertical load and braking force coefficient of each axle;

[0068] The maximum permissible pure electric braking torque for each axis is determined as the minimum value between the maximum permissible braking torque of the left and right drive motor assemblies of that axis and the maximum ground braking torque.

[0069] The maximum allowable pure hydraulic braking torque for each axle is determined as the minimum value between the maximum hydraulic braking torque of the hydraulic brake corresponding to the wheel connected to that axle and the maximum ground braking torque.

[0070] The maximum permissible electro-hydraulic combined braking torque for each axis is determined as the minimum of the sum of the maximum permissible braking torque of the left and right drive motor assemblies of that axis and the maximum hydraulic braking torque of the hydraulic brake, and the maximum ground braking torque.

[0071] Optionally, the slip ratio of each drive wheel is calculated based on the current vehicle speed and wheel angular velocity, using the following formula:

[0072]

[0073] In the formula, i represents the axle position. In the wheel-side driven mining truck described in the first aspect of the present invention, i can take values ​​from 1 to 3, where 1 corresponds to the front axle, 2 corresponds to the middle axle, and 3 corresponds to the rear axle; j represents the left and right positions of the wheels, and can take values ​​of 1 or 2, where 1 represents the left wheel and 2 represents the right wheel; s ij The slip ratio of wheel j on axis i is represented by u; the current vehicle speed is u; the tire radius is r; ω is ω. ij Let ω be the angular velocity of wheel j on axis i.

[0074] After obtaining the slip ratio of each drive wheel, the braking force coefficient of the corresponding drive wheel can be obtained according to the predetermined braking force coefficient-slip ratio relationship curve. In this invention, the drive wheel is the wheel connected to the central axle and the rear axle.

[0075] Optionally, the maximum ground braking force of the wheels connected to each axle is calculated based on the vertical load and braking force coefficient of each axle, using the following formula:

[0076]

[0077] In the formula, F b-i F represents the maximum ground braking force of the i-axis wheel. Z-i This represents the vertical load along the i-axis. This represents the braking force coefficient along the i-axis.

[0078] Optionally, the allocation of hydraulic and electric braking torques to each wheel based on the vehicle speed information, battery state of charge information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque includes:

[0079] Determine whether the battery charge state is greater than the set high charge threshold. If so, the target electric braking torque is 0. If the pure hydraulic braking torque can meet the braking force requirement at the same time, the hydraulic braking torque is distributed to each wheel according to distribution method a.

[0080] If the battery charge state is less than or equal to the set high charge threshold and the vehicle speed is not greater than the set electro-hydraulic brake switching speed threshold V1, then the target electric braking torque is 0. If the pure hydraulic braking torque can meet the braking force requirement at the same time, the hydraulic braking torque is distributed to each wheel according to distribution method a; otherwise, it is distributed according to distribution method b.

[0081] If the battery charge state is less than or equal to the set high charge threshold, and the vehicle speed is greater than the set electro-hydraulic brake switching speed threshold V1, and if pure electric braking can simultaneously meet the braking force requirements, then the hydraulic braking torque output of each wheel is 0, and the pure electric braking torque is distributed to each wheel according to the distribution method c.

[0082] If the battery state of charge is less than or equal to the set high charge threshold, and the vehicle speed is greater than the set electro-hydraulic braking switching speed threshold V1, and if pure electric braking does not simultaneously meet the braking force requirement, then it is determined that the composite braking torque can meet the braking force requirement: if it does not meet the requirement, then the electro-hydraulic composite braking torque is distributed to each wheel according to distribution method d; if it meets the requirement, then the electro-hydraulic composite braking torque is distributed to each wheel according to distribution method e; wherein:

[0083] Distribution method a: Distribute the hydraulic braking torque of each wheel according to the ratio corresponding to the ratio of the maximum allowable hydraulic braking force of each axle;

[0084] Distribution method b: The hydraulic braking torque of each wheel is output at 100% of the maximum allowable hydraulic braking torque of that wheel;

[0085] Distribution method c: The hydraulic braking torque output of each wheel is 0, and the pure electric braking torque of each wheel is distributed according to the ratio corresponding to the ratio of the maximum allowable pure electric braking torque of each axle;

[0086] Distribution method d: According to the principle of electric braking priority, the combined electro-hydraulic braking torque of each wheel is output at 100% of the maximum allowable combined electro-hydraulic braking torque of that wheel;

[0087] Allocation method e: Based on the principle of prioritizing electric braking, the electric braking and hydraulic braking torque of each wheel are allocated according to the ratio corresponding to the maximum allowable electro-hydraulic combined braking torque of each axle.

[0088] Optionally, the set high charge threshold is SOC = 98%. The electro-hydraulic braking switching speed threshold V1 can be set based on experience or experimentation for different models of mining trucks.

[0089] The above-mentioned braking torque distribution method can improve the braking energy recovery capability while meeting the braking force requirements.

[0090] Beneficial effects

[0091] Compared with the prior art, the present invention has the following advantages and progress:

[0092] (1) Considering the various braking forms of mining trucks and taking into account the influence of material quality changes, the braking force demand is calculated in different modes to make the distribution of braking torque more detailed and accurate, and to avoid excessive braking impact or insufficient braking force due to deviation in braking force request.

[0093] (2) The maximum ground braking force of the tire is estimated based on the slip ratio of the drive wheel and the load distribution under different material masses. Combined with the allowable braking torque of the drive motor assembly and the hydraulic braking capacity, the maximum allowable braking torque of each wheel is obtained, so that the braking capacity is estimated more accurately and the tire lock-up is prevented due to excessive output braking torque.

[0094] (3) Distributing braking torque based on the battery's state of charge level ensures that the battery does not overcharge due to regenerative braking. On this basis, the decision to output electric braking torque is made in conjunction with the vehicle speed level, which can prevent the low-speed electric brake motor from reversing. Furthermore, prioritizing electric braking, the braking torque is distributed according to the proportion of the maximum allowable braking torque of each axle, which ensures that the braking force output of each wheel is kept within the maximum braking capacity and obtains the maximum regenerative braking energy. Attached Figure Description

[0095] Figure 1 The diagram shown is a power architecture diagram of an embodiment of the wheel-side driven mining truck of the present invention;

[0096] Figure 2 The diagram shown is a schematic block diagram of the wheel-side drive mining truck braking control system of the present invention in one embodiment.

[0097] Figure 3 The diagram shown is a schematic flowchart of the braking force demand calculation process in one embodiment of the wheel-side drive mining truck braking control method of the present invention.

[0098] Figure 4 The diagram shown is a schematic flowchart of the maximum braking torque analysis in one embodiment of the wheel-side drive mining truck braking control method of the present invention.

[0099] Figure 5The figure shown is a schematic diagram of the braking force coefficient-slip ratio relationship curve in one embodiment of the wheel-side driven mining truck braking control method of the present invention.

[0100] Figure 6 The diagram shown is a schematic representation of the braking torque distribution process in one embodiment of the wheel-side driven mining truck braking control method of the present invention. Detailed Implementation

[0101] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details.

[0102] The technical concept of this invention is as follows: For new energy wheel-side driven mining trucks with electro-hydraulic composite braking function, considering the multiple braking modes of the mining truck and the influence of changes in material mass, the braking force demand is calculated by mode, making the results more detailed and accurate, avoiding excessive braking impact or insufficient braking force due to deviation in braking force request; based on the vehicle's operating status and load distribution under different material masses, and combined with the allowable braking torque of the drive motor assembly and the hydraulic braking capacity, the maximum allowable braking torque of each wheel is obtained, making the braking capacity estimation more accurate and preventing excessive output braking torque from causing tire lock-up; when distributing braking torque, under the premise of ensuring that the battery does not overcharge and avoiding reversal of the low-speed electric braking motor, the principle of electric braking priority is adopted, so that the braking force output of each wheel is kept within the maximum braking capacity and the maximum braking recovery energy is obtained.

[0103] Example 1

[0104] This embodiment describes a wheel-side driven mining truck, whose power architecture is as follows: Figure 1 As shown, it includes:

[0105] The hydraulic braking control system includes a hydraulic braking control unit and hydraulic brakes respectively installed for each wheel and controlled by the hydraulic braking control unit. The hydraulic brakes are used to output hydraulic braking torque to each corresponding wheel.

[0106] The drive motor assembly is set for each wheel connected to the central axle and the rear axle, and is used to drive the corresponding wheel to rotate and output electric braking torque to the corresponding wheel; the drive motor assembly is an assembly that integrates the power and transmission components of the motor, motor controller and reducer.

[0107] An energy recovery unit, including a battery, is used to recover braking energy when the drive motor assembly outputs electric braking torque to the wheels;

[0108] The hopper operation unit is equipped with a material quality detection device, such as a weighing sensor;

[0109] The vehicle operation status detection unit is used to collect vehicle operation status information;

[0110] The main controller is used to receive material quality information output by the material quality detection device, and to control the electric braking torque output of each drive motor assembly according to braking requirements, the material quality information, the state of charge of the battery and the vehicle operating status information, and / or to control the hydraulic braking torque output of each hydraulic brake through the hydraulic braking control unit.

[0111] The wheel-side driven mining truck in this embodiment also includes a hydraulic pump station, which consists of a motor, a hydraulic pump, an oil tank, etc., and is used to convert electrical energy into hydraulic oil pressure energy to provide power for the hydraulic cylinder to move; the hydraulic cylinder drives the hopper to complete the lifting action.

[0112] The wheel-side driven mining truck in this embodiment adopts a wheel-side drive form with a central axle and a rear axle. By setting hydraulic brakes for each wheel and drive motor assemblies for each rear wheel, and by collecting material quality information and vehicle operating status information, the main controller can dynamically distribute braking torque under different braking modes and material qualities based on the collected information. This allows the braking torque distribution scheme to more accurately adapt to the vehicle's braking needs in real-time braking mode, while maximizing the recovery of braking energy.

[0113] Example 2

[0114] like Figure 2 As shown in the figure, this embodiment introduces a braking control system for a wheel-side driven mining truck as described in Embodiment 1. The vehicle operation status detection unit of the wheel-side driven mining truck is equipped with a vehicle speed sensor. During the operation of the mining truck, the drive motor assembly feeds back the output shaft speed and electric braking torque limit to the main controller.

[0115] The braking control system of this embodiment includes: a brake pedal, an emergency stop switch, a deceleration lever, an accelerator pedal, a gear shift lever, and the main controller; wherein...

[0116] Different openings of the brake pedal correspond to different target accelerations. The emergency stop switch is used to transmit an emergency braking request to the main controller when it is pressed. The retarding handle includes multiple gears, each gear corresponding to a set of target vehicle speeds and target braking accelerations. For example, there can be 4 retarding gears. The target vehicle speeds of retarding gears 1-4 decrease sequentially, and the target braking accelerations increase sequentially.

[0117] The main controller is configured as follows:

[0118] The system receives material quality information output by the material quality detection device, vehicle speed information output by the vehicle speed sensor, opening information of the brake pedal and accelerator pedal, position information of the emergency stop switch, retarder handle and gear shift handle, output shaft speed and electric braking torque limit fed back by the drive motor assembly, and battery state of charge information.

[0119] Based on the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch, the retarder lever and the gear shift lever, and the material quality information, the braking force demand data is obtained by analysis.

[0120] Based on the output shaft speed, electric braking torque limit, and material mass information, the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft are analyzed and obtained.

[0121] Based on the vehicle speed information, battery state of charge information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque, the hydraulic braking torque and electric braking torque are allocated to each wheel.

[0122] For details on the specific functions of the main controller, please refer to the relevant content in the following embodiments regarding the control method.

[0123] Example 3

[0124] This embodiment introduces a braking control method for a wheel-side driven mining truck as described in Embodiment 1. This braking control method can be implemented by the main controller of the wheel-side driven mining truck described in Embodiment 1, such as the vehicle controller of an actual mining truck.

[0125] The braking control method of this embodiment can be triggered by any action of the brake pedal, emergency stop switch, retarder lever, accelerator pedal, or gear shift lever in the braking mechanism. After triggering, it performs periodic closed-loop control of vehicle speed or braking acceleration. During the closed-loop control process, it performs braking force demand calculation, maximum permissible braking torque estimation, and braking torque distribution. The main steps include:

[0126] S1, acquires material quality information of mining truck, vehicle speed information, brake pedal and accelerator pedal opening information, emergency stop switch and deceleration handle position information, output shaft speed and electric braking torque limit of drive motor assembly, and battery charge status information.

[0127] S2, based on the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch and the retarder handle, and the material mass information, the braking force demand data is obtained through analysis;

[0128] S3. Based on the output shaft speed, electric braking torque limit, and material mass information, the maximum allowable pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque of each shaft are analyzed and obtained.

[0129] S4. Based on the vehicle speed information, battery charge status information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque, the hydraulic braking torque and electric braking torque are allocated to each wheel.

[0130] The following provides a detailed explanation of each step.

[0131] I. Data Acquisition

[0132] In this embodiment, in the aforementioned step S1, the material mass can be obtained by the weighing sensor installed on the hopper, the vehicle speed can be obtained by the vehicle speed sensor, the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch and the retarder handle, the output shaft speed of the drive motor assembly and the limit of the electric braking torque, and the battery charge status information can all be obtained with reference to the prior art.

[0133] II. Braking Force Demand Calculation

[0134] refer to Figure 3 In this embodiment, the calculation process for braking force requirement is as follows:

[0135] Based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift lever, and deceleration lever, the braking mode is determined. The braking modes include: emergency stop braking mode, service braking mode, deceleration braking mode, coasting braking mode, and deceleration speed adjustment mode. Specifically, the braking mode determination process includes:

[0136] Based on the urgency of braking demand under various vehicle braking modes, this embodiment first determines whether the emergency stop switch has been pressed, then determines whether the brake pedal has been activated, and subsequently determines whether the retarder lever has been activated. Specifically:

[0137] like Figure 3 If the emergency stop switch is in the pressed position, the braking mode is the emergency stop braking mode, and the corresponding target braking acceleration is the maximum value.

[0138] If the brake pedal opening is greater than 0 degrees, the braking mode is the service braking mode. The corresponding target braking acceleration is calculated based on the brake pedal opening, and can be referenced from existing technology.

[0139] If the slow-moving gear is greater than 0, and the current vehicle speed is less than a multiple of the target speed corresponding to the slow-moving gear, then the braking mode is the slow-moving speed adjustment mode; otherwise, it is determined whether the accelerator pedal opening is not greater than 0 or the gear shift lever is in neutral (N). If not, the mining truck is in non-braking mode; if so, the braking mode is coasting braking mode, and the corresponding target braking acceleration is the preset coasting braking acceleration. The preferred multiple here is 1.5 times.

[0140] The calculation method for braking force demand under different braking modes is as follows.

[0141] 1) If the mining truck is in non-braking mode, the braking force requirement is 0.

[0142] 2) If the braking mode is slow-speed adjustment mode, the braking force requirement is calculated based on the deviation between the target speed corresponding to the slow-speed gear and the current speed, and the current material mass. The specific process is as follows:

[0143] Calculate the deviation between the target speed and the current speed corresponding to the slow-moving gear;

[0144] Based on the rated load ratio range of the current material mass, query the preset material mass and PID parameter mapping table to determine the PID parameters for the current material mass used for vehicle speed closed-loop PID control.

[0145] In slow-speed adjustment mode, the braking force requirement is calculated based on the deviation between the target vehicle speed and the current vehicle speed, as well as the determined PID parameters. The calculation formula is as follows:

[0146]

[0147] In the formula, k represents the execution cycle count of the closed-loop PID control, F1(k) is the braking force requirement of the kth control cycle in the slow speed regulation mode; Δv(k) and Δv(k-1) are the deviations between the target vehicle speed and the current vehicle speed in the kth and k-1th control cycles, respectively; P1, I1, and D1 are the control parameters of the vehicle speed closed-loop PID control.

[0148] 3) If the braking mode is any other than the slow-speed adjustment mode, the target braking acceleration is determined based on the opening of the brake pedal, the opening of the accelerator pedal, or the position of the emergency stop switch. The current braking acceleration is calculated based on the current vehicle speed. Then, based on the deviation between the target braking acceleration and the current braking acceleration, and the current material mass, the braking force requirement is calculated, including:

[0149] Calculate the current braking acceleration based on the current vehicle speed;

[0150] Calculate the deviation between the target braking acceleration and the current braking acceleration;

[0151] Based on the rated load ratio range of the current material mass, query the preset material mass and PID parameter mapping table to determine the PID parameters for the current material mass used for closed-loop PID control of braking acceleration.

[0152] The braking force requirement is calculated based on the deviation between the target braking acceleration and the current braking acceleration, as well as the determined PID parameters. The calculation formula is as follows:

[0153]

[0154] In the formula, k represents the execution cycle count of the closed-loop PID control, F1(k) is the braking force requirement in the k-th control cycle under emergency braking mode, service braking mode, slow braking mode or coasting braking mode; △a(k) and △a(k-1) are the deviations between the target braking acceleration and the current braking acceleration in the k-th and k-1-th control cycles, respectively; P2, I2 and D2 are the control parameters of the closed-loop PID control of braking acceleration.

[0155] In this embodiment, when selecting PID control parameters, the proportion of material mass to rated load is divided into multiple proportional ranges: [0, 30%], (30%, 60%), (60%, 90%), and above 90% (including overload). Each proportional range corresponds to a set of vehicle speed closed-loop PID control parameters and braking acceleration closed-loop PID control parameters. The specific settings of the PID parameters can be tested and calibrated according to the actual vehicle model to ensure a faster response to braking force demand calculated based on the corresponding PID closed-loop when the material mass is larger.

[0156] Table 1 below provides a specific mapping relationship between closed-loop PID control parameters for vehicle speed and the proportional range of material mass. Table 2 provides a mapping relationship between closed-loop PID control parameters for braking acceleration and the proportional range of material mass.

[0157] Table 1

[0158] <![CDATA[P1]]> <![CDATA[I1]]> <![CDATA[D1]]> 0-30% of the load 50 4 2 30% to 60% of the rated load 65 5 2 60%–90% of the rated load 75 5.5 2 >90% of the load 80 6 2

[0159] Table 2

[0160] <![CDATA[P2]]> <![CDATA[I2]]> <![CDATA[D2]]> 0-30% of the load 4 0.5 0.2 30% to 60% of the rated load 4.6 0.8 0.2 60%–90% of the rated load 5.2 1 0.2 >90% of the load 6 1.2 0.2

[0161] III. Calculation of Braking Capacity, i.e., Maximum Braking Torque

[0162] In the braking control method of this embodiment, the maximum allowable pure electric braking torque, the maximum pure hydraulic braking torque, and the maximum electro-hydraulic combined braking torque of each shaft are analyzed based on the output shaft speed, the limit of electric braking torque, and the material mass information. The specific implementation process is as follows.

[0163] S31, calculate the slip ratio of each drive wheel based on the current vehicle speed and wheel angular velocity; whereby the wheel angular velocity can be determined based on the output shaft speed fed back from the drive motor assembly, and the formula for calculating the drive wheel slip ratio is:

[0164]

[0165] In the formula, i represents the axle position. In the wheel-side driven mining truck described in the first aspect of the present invention, i can take values ​​from 1 to 3, where 1 corresponds to the front axle, 2 corresponds to the middle axle, and 3 corresponds to the rear axle; j represents the left and right positions of the wheels, and can take values ​​of 1 or 2, where 1 represents the left wheel and 2 represents the right wheel; s ijThe slip ratio of wheel j on axis i is represented by u; the current vehicle speed is u; the tire radius is r; ω is ω. ij Let ω be the angular velocity of wheel j on axis i.

[0166] After obtaining the slip ratio of each drive wheel, according to the pre-determined braking force coefficient-slip ratio relationship curve, such as... Figure 5 The curve shown can be used to obtain the braking force coefficient of the corresponding drive wheel.

[0167] S32, based on the slip ratio s of each drive wheel ij Determine the braking force coefficient of each drive wheel.

[0168] S33, for the left and right wheels (i.e., drive wheels) connected to the same axle of each center and rear axle, the smaller braking force coefficient is used as the wheel braking coefficient for that axle:

[0169] S34 uses the smaller of the braking coefficients of the center axle and the rear axle as the braking force coefficient of the driven wheel on the front axle.

[0170] S35, calculate the vertical load F of each axis based on the material mass. Z-i This can be achieved using existing technologies, and will not be elaborated upon.

[0171] S36, calculate the maximum ground braking force of the wheels connected to each axle based on the vertical load and braking force coefficient of each axle, using the following formula:

[0172]

[0173] In the formula, F b-i F represents the maximum ground braking force of the i-axis wheel. Z-i This represents the vertical load along the i-axis. This represents the braking force coefficient along the i-axis.

[0174] S37, the maximum permissible pure electric braking torque M of each axle Eb-i The maximum permissible braking torque T of the left and right drive motor assemblies on this shaft is determined as follows: Eb-i1 T Eb-i2 With maximum ground braking torque F b-i Minimum value in r:

[0175] M Eb-i =min(F b-i ·r,T Eb-i1 T Eb-i2 ).

[0176] S38, the maximum permissible pure hydraulic braking torque M of each axis Hb-iThe maximum hydraulic braking torque T of the hydraulic brake corresponding to the wheel connected to this axle is determined as follows: Hb-i With the maximum ground braking torque F b-i Minimum value in r:

[0177] M Hb-i =min(F b-i ·r,T Hb-i ).

[0178] S39, the maximum permissible electro-hydraulic combined braking torque M of each axis EHb-i The value T is defined as: the sum of the maximum permissible braking torque of the left and right drive motor assemblies of this shaft and the maximum hydraulic braking torque of the hydraulic brake. Eb-i1 +T Hb-i T Eb-i2 +T Hb-i With the maximum ground braking torque F b-i Minimum value in r:

[0179] M EHb-i =min(F b-i ·r,T Eb-i1 +T Hb-i T Eb-i2 +T Hb-i ).

[0180] Based on the above calculations, the braking capacity of the mining truck under different braking methods can be obtained. When distributing the braking torque in the subsequent process, the distribution is made according to the braking capacity so that the braking force output of each wheel remains within the maximum braking capacity.

[0181] IV. Braking Torque Distribution

[0182] In distributing braking torque, this embodiment prioritizes electric braking, ensuring the battery doesn't overcharge and preventing the low-speed electric brake motor from reversing. It allocates braking torque based on the maximum allowable braking torque ratio for each axle, keeping the braking force output of each wheel within its maximum braking capacity and maximizing regenerative braking energy. (Reference) Figure 6 As shown, the braking torque distribution process includes:

[0183] S41, determine whether the battery state of charge is greater than the set high charge threshold. If so, the target electric braking torque is 0. If the pure hydraulic braking torque can meet the braking force requirement at the same time, the hydraulic braking torque is distributed to each wheel according to distribution method a. If the battery state of charge is less than or equal to the set high charge threshold, and the vehicle speed is not greater than the set electro-hydraulic braking switching speed threshold V1, the target electric braking torque is 0. If the pure hydraulic braking torque can meet the braking force requirement at the same time, the hydraulic braking torque is distributed to each wheel according to distribution method a. Otherwise, the distribution is carried out according to distribution method b.

[0184] If the battery charge state is less than or equal to the set high charge threshold, and the vehicle speed is greater than the set electro-hydraulic brake switching speed threshold V1, and if pure electric braking can simultaneously meet the braking force requirements, then the hydraulic braking torque output of each wheel is 0, and the pure electric braking torque is distributed to each wheel according to the distribution method c.

[0185] If the battery state of charge is less than or equal to the set high charge threshold, and the vehicle speed is greater than the set electro-hydraulic braking switching speed threshold V1, and if pure electric braking does not simultaneously meet the braking force requirement, then it is determined that the composite braking torque can meet the braking force requirement: if it does not meet the requirement, then the electro-hydraulic composite braking torque is distributed to each wheel according to distribution method d; if it meets the requirement, then the electro-hydraulic composite braking torque is distributed to each wheel according to distribution method e; wherein:

[0186] Distribution method a: Distribute the hydraulic braking torque of each wheel according to the ratio corresponding to the ratio of the maximum allowable hydraulic braking force of each axle;

[0187] Distribution method b: The hydraulic braking torque of each wheel is output at 100% of the maximum allowable hydraulic braking torque of that wheel;

[0188] Distribution method c: The hydraulic braking torque output of each wheel is 0, and the pure electric braking torque of each wheel is distributed according to the ratio corresponding to the ratio of the maximum allowable pure electric braking torque of each axle;

[0189] Distribution method d: According to the principle of electric braking priority, the combined electro-hydraulic braking torque of each wheel is output at 100% of the maximum allowable combined electro-hydraulic braking torque of that wheel;

[0190] Allocation method e: Based on the principle of prioritizing electric braking, the electric braking and hydraulic braking torque of each wheel are allocated according to the ratio corresponding to the maximum allowable electro-hydraulic combined braking torque of each axle.

[0191] In this embodiment, the high charge threshold is set to SOC = 98%. The electro-hydraulic braking switching speed threshold V1 can be set based on experience or experimental calibration for different models of mining trucks.

[0192] The braking force control method proposed in this invention can also be applied to other wheel-side drive systems.

[0193] In summary, the present invention can avoid excessive braking impact or insufficient braking force caused by deviation in braking force request, prevent excessive output braking torque from causing tire lock-up, keep the braking force output of each wheel within the maximum braking capacity, and obtain the maximum regenerative braking energy.

[0194] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0195] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0196] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0197] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0198] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A wheel-side driven mining truck, characterized in that, include: The hydraulic braking control system includes a hydraulic braking control unit and hydraulic brakes respectively installed for each wheel and controlled by the hydraulic braking control unit. The hydraulic brakes are used to output hydraulic braking torque to each corresponding wheel. The drive motor assembly is provided for each wheel connected to the central axle and the rear axle, and is used to drive the corresponding wheel to rotate and output electric braking torque to the corresponding wheel. An energy recovery unit, including a battery, is used to recover braking energy when the drive motor assembly outputs electric braking torque to the wheels; The hopper operation unit is equipped with a material quality detection device; The vehicle operation status detection unit is used to collect vehicle operation status information; The main controller is used to receive material quality information output by the material quality detection device, and to control the electric braking torque output of each drive motor assembly according to the braking force requirements, the material quality information, the state of charge of the battery and the vehicle operating status information, and / or to control the hydraulic braking torque output of each hydraulic brake through the hydraulic braking control unit. The braking control system of the wheel-side driven mining truck includes a brake pedal, an emergency stop switch, a deceleration lever, an accelerator pedal, a gear shift lever, and the main controller. The method for obtaining the braking force requirement includes: determining the braking mode based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift lever, and retarder lever. The braking modes include: emergency stop braking mode, service braking mode, slow braking mode, coasting braking mode, and slow speed adjustment mode. If the braking mode is slow speed adjustment mode, the braking force requirement is calculated based on the deviation between the target vehicle speed and the current vehicle speed corresponding to the slow gear, and the current material mass. This includes: calculating the deviation between the target vehicle speed and the current vehicle speed corresponding to the slow gear; querying a preset material mass and PID parameter mapping table based on the rated load ratio range of the current material mass to determine the PID parameters for closed-loop PID control of the vehicle speed corresponding to the current material mass; and calculating the braking force requirement based on the deviation between the target vehicle speed and the current vehicle speed and the determined PID parameters.

2. The wheel-side driven mining truck according to claim 1, characterized in that, The vehicle operating status detection unit includes a vehicle speed sensor; The different opening degrees of the brake pedal correspond to different target accelerations. The emergency stop switch is used to transmit an emergency braking request to the main controller. The retarder handle includes multiple gears, each gear corresponding to a set of target vehicle speeds and target braking accelerations. The main controller is configured as follows: The system receives material quality information output by the material quality detection device, vehicle speed information output by the vehicle speed sensor, opening information of the brake pedal and accelerator pedal, position information of the emergency stop switch, retarder handle and gear shift handle, output shaft speed and electric braking torque limit fed back by the drive motor assembly, and battery state of charge information. Based on the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch, the retarder lever and the gear shift lever, and the material quality information, the braking force demand data is obtained by analysis. Based on the output shaft speed, electric braking torque limit, and material mass information, the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft are analyzed and obtained. Based on the vehicle speed information, battery state of charge information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque, the hydraulic braking torque and electric braking torque are allocated to each wheel.

3. A braking control method for a wheel-side driven mining truck as described in claim 1, characterized in that, include: Acquire material quality information of the mining truck, vehicle speed information, brake pedal and accelerator pedal opening information, emergency stop switch and deceleration handle position information, output shaft speed and electric braking torque limit of the drive motor assembly, and battery charge status information. Based on the opening information of the brake pedal and accelerator pedal, the position information of the emergency stop switch, gear shift lever and retarder lever, and the material mass information, the braking force demand data is obtained by analysis. Based on the output shaft speed, electric braking torque limit, and material mass information, the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft are analyzed and obtained. Based on the vehicle speed information, battery charge status information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque, the hydraulic braking torque and electric braking torque are allocated to each wheel. The method for obtaining braking force demand data includes: determining the braking mode based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift lever and deceleration lever. The braking modes include: emergency stop braking mode, service braking mode, deceleration braking mode, coasting braking mode and deceleration speed adjustment mode. If the braking mode is a slow-speed adjustment mode, the braking force requirement is calculated based on the deviation between the target speed and the current speed corresponding to the slow-speed gear, and the current material mass. This includes: calculating the deviation between the target speed and the current speed corresponding to the slow-speed gear; querying a preset material mass and PID parameter mapping table based on the rated load ratio range of the current material mass to determine the PID parameters for closed-loop PID control of the current material mass; and calculating the braking force requirement based on the deviation between the target speed and the current speed and the determined PID parameters.

4. The braking control method according to claim 3, characterized in that, If, based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift switch, and retarder handle, it is determined that the braking mode is other than the slow speed adjustment mode, then the target braking acceleration is determined based on the opening of the brake pedal, the opening of the accelerator pedal, or the position of the emergency stop switch, and the current braking acceleration is calculated based on the current vehicle speed. Then, based on the deviation between the target braking acceleration and the current braking acceleration, and the current material mass, the braking force requirement is calculated. If the mining truck is in non-braking mode, the braking force requirement is 0.

5. The braking control method according to claim 4, characterized in that, The retarder handle includes multiple retarder levels, with the target vehicle speed decreasing sequentially and the target braking acceleration increasing sequentially. The step of determining the braking mode based on the opening information of the brake pedal and accelerator pedal, and the position information of the emergency stop switch, gear shift lever, and retarder lever includes: If the emergency stop switch is in the pressed position, the braking mode is the emergency stop braking mode, and the corresponding target braking acceleration is the maximum value; If the brake pedal opening is greater than 0 degrees, the braking mode is the service braking mode, and the corresponding target braking acceleration is calculated based on the brake pedal opening. If the slow-moving gear is greater than 0 and the current vehicle speed is less than a multiple of the target speed corresponding to the slow-moving gear, the braking mode is slow-moving speed adjustment mode; otherwise, it is determined whether the accelerator pedal opening is not greater than 0 or the gear shift lever is in N gear. If not, the mining truck is in non-braking mode; if so, the braking mode is coasting braking mode, and the corresponding target braking acceleration is the preset coasting braking acceleration.

6. The braking control method according to claim 3, characterized in that, The braking force requirement is calculated based on the deviation between the target vehicle speed and the current vehicle speed, as well as the determined PID parameters. The calculation formula is as follows: ， In the formula, This represents the execution cycle count of the closed-loop PID control. For the slow speed regulation mode, the first Braking force requirements for each control cycle; , The first The and the first The deviation between the target vehicle speed and the current vehicle speed in each control cycle; , , These are the control parameters for the vehicle speed closed-loop PID control.

7. The braking control method according to claim 4, characterized in that, The calculation of braking force demand based on the deviation between the target braking acceleration and the current braking acceleration, and the current material mass, includes: Calculate the current braking acceleration based on the current vehicle speed; Calculate the deviation between the target braking acceleration and the current braking acceleration; Based on the rated load ratio range of the current material mass, query the preset material mass and PID parameter mapping table to determine the PID parameters for the current material mass used for closed-loop PID control of braking acceleration. The braking force requirement is calculated based on the deviation between the target braking acceleration and the current braking acceleration, as well as the determined PID parameters.

8. The braking control method according to claim 7, characterized in that, The braking force requirement is calculated based on the deviation between the target braking acceleration and the current braking acceleration, as well as the determined PID parameters. The calculation formula is as follows: ， In the formula, This represents the execution cycle count of the closed-loop PID control. For emergency stop braking mode, service braking mode, slow braking mode, or coasting braking mode, the first Braking force requirements for each control cycle; , The first The and the first The deviation between the target braking acceleration and the current braking acceleration in each control cycle; , , These are the control parameters for the closed-loop PID control of braking acceleration.

9. The braking control method according to any one of claims 6-8, characterized in that, The rated load ratio range includes [0, 30%], (30%, 60%], (60%, 90%] and above 90%; In the preset material mass and PID parameter mapping table, the PID parameters are set to satisfy the following condition: the greater the material mass, the faster the braking force demand response when using the corresponding PID parameters for closed-loop PID control.

10. The braking control method according to any one of claims 6-8, characterized in that, In the preset material mass and PID parameter mapping table, the PID parameters are set to satisfy the following: the greater the proportion of material mass to rated load, the larger the values ​​of parameters P and I in the PID parameters, while the value of parameter D remains unchanged.

11. The braking control method according to claim 4, characterized in that, In the preset material mass and PID parameter mapping table, the mapping relationship between the material mass's proportion of the rated load and the vehicle speed closed-loop PID control parameters is as follows: 。 12. The braking control method according to claim 7, characterized in that, In the preset material mass and PID parameter mapping table, the mapping relationship between the material mass as a percentage of the rated load and the braking acceleration closed-loop PID control parameters is as follows: 。 13. The braking control method according to any one of claims 3-8, characterized in that, The process involves analyzing the output shaft speed, electric braking torque limit, and material mass information to determine the maximum permissible pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic combined braking torque for each shaft, including: Calculate the slip ratio of each drive wheel based on the current vehicle speed and wheel angular velocity; The braking force coefficient of each drive wheel is determined based on the slip ratio of each drive wheel; For the left and right wheels on the same axle connected to each center axle and rear axle, the smaller braking force coefficient is taken as the wheel braking coefficient of that axle. The smaller of the braking coefficients of the center axle and the rear axle is used as the braking force coefficient of the driven wheel on the front axle. Calculate the vertical load on each axis based on the material mass; Calculate the maximum ground braking force of the wheels connected to each axle based on the vertical load and braking force coefficient of each axle; The maximum permissible pure electric braking torque for each axis is determined as the minimum value between the maximum permissible braking torque of the left and right drive motor assemblies of that axis and the maximum ground braking torque. The maximum allowable pure hydraulic braking torque for each axle is determined as the minimum value between the maximum hydraulic braking torque of the hydraulic brake corresponding to the wheel connected to that axle and the maximum ground braking torque. The maximum permissible electro-hydraulic combined braking torque for each axis is determined as the minimum of the sum of the maximum permissible braking torque of the left and right drive motor assemblies of that axis and the maximum hydraulic braking torque of the hydraulic brake, and the maximum ground braking torque.

14. The braking control method according to claim 13, characterized in that, The formula for calculating the slip ratio of each drive wheel based on the current vehicle speed and wheel angular velocity is as follows: ， In the formula, Indicates the axle position; Indicates the left and right positions of the wheels; express axis The slip ratio of the wheel; Current vehicle speed; The radius of the tire; for axis The angular velocity of the wheel.

15. The braking control method according to claim 13, characterized in that, The formula for calculating the maximum ground braking force of the wheels connected to each axle based on the vertical load and braking force coefficient of each axle is as follows: ， In the formula, express The maximum ground braking force of the axle wheel, express Vertical load on the shaft, express Braking force coefficient of the shaft.

16. The braking control method according to any one of claims 3-8, characterized in that, The method of allocating hydraulic and electric braking torques to each wheel based on vehicle speed information, battery state of charge information, braking force demand data, maximum pure electric braking torque, maximum pure hydraulic braking torque, and maximum electro-hydraulic composite braking torque includes: Determine whether the battery charge state is greater than the set high charge threshold. If so, the target electric braking torque is 0. If the pure hydraulic braking torque can meet the braking force requirement at the same time, the hydraulic braking torque is distributed to each wheel according to distribution method a. If the battery charge state is less than or equal to the set high charge threshold and the vehicle speed is not greater than the set electro-hydraulic brake switching speed threshold V1, then the target electric braking torque is 0. If the pure hydraulic braking torque can meet the braking force requirement at the same time, the hydraulic braking torque is distributed to each wheel according to distribution method a; otherwise, it is distributed according to distribution method b. If the battery charge state is less than or equal to the set high charge threshold, and the vehicle speed is greater than the set electro-hydraulic brake switching speed threshold V1, and if pure electric braking can simultaneously meet the braking force requirements, then the hydraulic braking torque output of each wheel is 0, and the pure electric braking torque is distributed to each wheel according to the distribution method c. If the battery state of charge is less than or equal to the set high charge threshold, and the vehicle speed is greater than the set electro-hydraulic braking switching speed threshold V1, and if pure electric braking does not simultaneously meet the braking force requirement, then it is determined that the composite braking torque can meet the braking force requirement: if it does not meet the requirement, then the electro-hydraulic composite braking torque is distributed to each wheel according to distribution method d; if it meets the requirement, then the electro-hydraulic composite braking torque is distributed to each wheel according to distribution method e; wherein: Distribution method a: Distribute the hydraulic braking torque of each wheel according to the ratio corresponding to the ratio of the maximum allowable hydraulic braking force of each axle; Distribution method b: The hydraulic braking torque of each wheel is output at 100% of the maximum allowable hydraulic braking torque of that wheel; Distribution method c: The hydraulic braking torque output of each wheel is 0, and the pure electric braking torque of each wheel is distributed according to the ratio corresponding to the ratio of the maximum allowable pure electric braking torque of each axle; Distribution method d: According to the principle of electric braking priority, the combined electro-hydraulic braking torque of each wheel is output at 100% of the maximum allowable combined electro-hydraulic braking torque of that wheel; Allocation method e: Based on the principle of prioritizing electric braking, the electric braking and hydraulic braking torque of each wheel are allocated according to the ratio corresponding to the maximum allowable electro-hydraulic combined braking torque of each axle.

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