Longitudinal vehicle speed estimation method and device for vehicle driven by hub motor

Abstract

The invention provides a longitudinal vehicle speed estimation method and device for a hub motor driven vehicle, and relates to the technical field of longitudinal vehicle speed estimation.The longitudinal vehicle speed estimation method comprises the steps that the wheel speeds of four wheels of the vehicle are collected in real time and ranked, whether the vehicle is in a braking working condition or not is judged, and a corresponding wheel speed reference is selected based on the working condition to calculate an initial wheel speed difference value; comparing the difference value with a corresponding threshold value, and performing torque dynamic control on the target wheel as required to obtain a corrected rear wheel speed difference value; calculating the confidence coefficient of each wheel based on the difference between the corrected wheel speed and the initial wheel speed; the linear speed of each wheel is converted into a longitudinal speed component by combining the position relation between the wheels and the mass center of the vehicle; performing weighted averaging by taking the confidence coefficient as a weight to obtain a longitudinal reference vehicle speed; by actively correcting the abnormal wheel speed and quantifying the reliability of the wheel speed, the accuracy of longitudinal vehicle speed estimation is improved, and reliable input is provided for a vehicle stability controller.

Description

Technical Field

[0001] This invention relates to the technical field of longitudinal vehicle speed estimation, and in particular to a method and apparatus for estimating the longitudinal vehicle speed of a hub motor driven vehicle. Background Technology

[0002] With the rapid development of electric vehicles and intelligent driving technologies, in-wheel motor-driven vehicles have gradually become a research hotspot due to their compact structure and high transmission efficiency. Vehicle stability control is one of the core functions of intelligent driving systems, and the accuracy of control strategies such as yaw control and anti-slip measures directly depends on the accurate estimation of the vehicle's longitudinal speed. In traditional vehicles, vehicle speed is usually estimated by combining wheel speed sensor signals with a vehicle dynamics model. This method has high reliability under normal driving conditions.

[0003] For in-wheel motor-driven vehicles, the unique driving method presents new challenges for speed estimation. Since each wheel is equipped with an independent drive motor, wheel speed signals become the primary source of vehicle speed information. Existing technologies commonly employ a weighted fusion method based on four-wheel wheel speeds, evaluating the reliability of each wheel speed signal using confidence factors. However, when the vehicle is under extreme conditions (such as simultaneous wheel slippage or wheel lock-up), the confidence factors of all wheel speed sensors significantly decrease, causing traditional wheel speed-based speed estimation methods to completely fail. In such situations, the lack of accurate vehicle speed input parameters in the vehicle stability control system not only affects control performance but may also lead to false activation of the controller, posing a potential threat to driving safety. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for estimating the longitudinal speed of a vehicle driven by a hub motor, thereby alleviating the technical problem that the longitudinal speed cannot be accurately obtained when the wheel speed confidence decreases due to wheel slippage or locking.

[0005] In a first aspect, the present invention provides a method for estimating the longitudinal speed of a vehicle driven by a hub motor, comprising: Real-time acquisition and sorting of the vehicle's four wheel speeds, outputting the sorted wheel speeds and corresponding wheel identifiers; Determine whether the vehicle is in braking condition, and calculate the initial wheel speed difference based on the corresponding wheel speed reference. The wheel speed difference is compared with the threshold value corresponding to the working condition result, and the torque of the target wheel is dynamically controlled as needed to obtain the corrected wheel speed difference of the target wheel. The confidence level of each wheel is calculated based on the corrected wheel speed difference and the initial wheel speed difference. Based on the positional relationship between the wheels and the vehicle's center of gravity, the linear velocities of each wheel are converted into corresponding longitudinal velocity components of the vehicle. The longitudinal reference speed of the vehicle is obtained by weighting the confidence levels of each wheel.

[0006] In an optional implementation, the step of determining whether the vehicle is in braking condition and selecting the corresponding wheel speed reference to calculate the initial wheel speed difference based on the condition result includes: If the vehicle is in braking condition, the initial wheel speed difference is calculated based on the maximum wheel speed among the four wheels. If the vehicle is not braking, the initial wheel speed difference is calculated based on the lowest wheel speed among the four wheels.

[0007] In an optional implementation, the step of comparing the wheel speed difference with the threshold value corresponding to the working condition result, and performing dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel includes: When the vehicle is under braking and the wheel speed difference exceeds the locking threshold, the torque increase value is calculated based on the braking torque of each wheel. Select the wheel with the lowest wheel speed and the diagonal wheel opposite the wheel with the lowest wheel speed, and perform torque increase control according to the torque increase value to correct the locking state of the target wheel and the corrected wheel speed difference; the target wheel includes the wheel with the lowest wheel speed and the diagonal wheel opposite the wheel with the lowest wheel speed.

[0008] In an optional implementation, the step of comparing the wheel speed difference with the threshold value corresponding to the working condition result, and performing dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel includes: When the vehicle is in a non-braking condition and the wheel speed difference exceeds the slippage threshold, the torque reduction value is calculated based on the driving torque of each wheel. Select the wheel with the maximum wheel speed and the diagonal wheel opposite the wheel with the maximum wheel speed, and perform torque reduction control according to the torque reduction value to correct the slippage state of the target wheel and the wheel speed difference after correction; the target wheel includes the wheel with the maximum wheel speed and the diagonal wheel opposite the wheel with the maximum wheel speed.

[0009] In an optional implementation, the step of calculating the confidence level of each wheel based on the corrected wheel speed difference and the initial wheel speed difference includes: Based on the preset threshold intervals where the corrected wheel speed difference and the initial wheel speed difference are located, select the corresponding piecewise function to calculate the confidence level of each wheel.

[0010] In an optional implementation, the step of converting the linear velocity of each wheel into a corresponding longitudinal velocity component of the vehicle based on the positional relationship between the wheel and the vehicle's center of gravity includes: By combining the vehicle's yaw rate, track width, and front wheel angle, the linear velocities of the front and rear wheels are adapted and converted to obtain the longitudinal velocity components of each wheel.

[0011] In an optional implementation, the step of obtaining the vehicle's longitudinal reference speed by weighted averaging using the confidence levels of each wheel includes: The longitudinal reference speed of the vehicle is obtained by multiplying the confidence level of each wheel by its corresponding longitudinal velocity component, summing the results, and then dividing by the sum of the confidence levels of each wheel.

[0012] In a second aspect, the present invention provides a longitudinal speed estimation device for a hub motor driven vehicle, comprising: The data acquisition module collects the wheel speeds of the vehicle's four wheels in real time, sorts them, and outputs the sorted wheel speeds and corresponding wheel identifiers. The first calculation module determines whether the vehicle is in braking condition and selects the corresponding wheel speed reference to calculate the initial wheel speed difference based on the condition result. The correction module compares the wheel speed difference with the threshold value corresponding to the working condition result, and performs dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel. The second calculation module calculates the confidence level of each wheel based on the corrected wheel speed difference and the initial wheel speed difference; The conversion module converts the linear velocity of each wheel into the corresponding longitudinal velocity component of the vehicle based on the positional relationship between the wheel and the vehicle's center of gravity. The weighting module uses the confidence level of each wheel as a weight to calculate the longitudinal reference speed of the vehicle.

[0013] Thirdly, the present invention provides an electronic device including a memory, a processor, and a program stored in the memory and capable of running on the processor, wherein the processor executes the program to implement the method as described in any of the foregoing embodiments.

[0014] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed, implements the method described in any of the foregoing embodiments.

[0015] This invention provides a method and device for estimating the longitudinal speed of a vehicle driven by a hub motor. The core idea is based on the principle that wheels with lower speeds under driving conditions and wheels with higher speeds under braking conditions are closer to the actual vehicle speed. By monitoring the wheel speeds of the four wheels in real time, sorting them, and judging the operating conditions, the wheel speed difference is calculated and compared with a threshold value. If the threshold is exceeded, dynamic torque control (torque reduction / increase) is performed on the target wheels (the wheel with the highest wheel speed and the diagonal wheel when slipping, and the wheel with the lowest wheel speed and the diagonal wheel when locked) to correct the wheel speed and improve the confidence level. Then, the confidence level of each wheel is calculated by a piecewise function, and the wheel linear velocity is converted into a longitudinal speed component by combining vehicle parameters. Finally, a weighted average is calculated with confidence level as the weight to obtain an accurate reference speed, ensuring the reliable operation of the vehicle stability controller.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a method for estimating the longitudinal speed of a vehicle driven by a hub motor, as provided in an embodiment of the present invention; Figure 2 A flowchart illustrating another method for estimating the longitudinal speed of a hub motor-driven vehicle, as provided in an embodiment of the present invention. Figure 3 A schematic diagram of the functional modules of a longitudinal speed estimation device for a hub motor driven vehicle provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the hardware architecture of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions 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, 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.

[0021] Currently, when wheel slippage or locking occurs in hub motor-driven vehicles, the confidence level of wheel speed decreases, leading to inaccurate acquisition of longitudinal vehicle speed. Based on this, the present invention provides a method and apparatus for estimating longitudinal vehicle speed in hub motor-driven vehicles, which can dynamically adjust and correct the error in reference vehicle speed caused by wheel slippage or locking based on the confidence level of reference vehicle speed, thereby improving the accuracy of longitudinal vehicle speed.

[0022] To facilitate understanding of this embodiment, a method for estimating the longitudinal speed of a hub motor-driven vehicle, disclosed in this embodiment of the invention, will first be described in detail. This method can be applied to a vehicle controller.

[0023] Figure 1 A flowchart illustrating a method for estimating the longitudinal speed of a vehicle driven by a hub motor, provided in an embodiment of the present invention.

[0024] Reference Figure 1 The method includes the following steps: S102, collects and sorts the wheel speeds of the four wheels of the vehicle in real time, and outputs the sorted wheel speeds and corresponding wheel identifiers. Here, the wheel speed signals of the four wheels—left front (FL), right front (FR), left rear (RL), and right rear (RR)—are collected, sorted numerically, and associated with the corresponding wheel identifiers. S104, determine whether the vehicle is in braking condition, and select the corresponding wheel speed reference to calculate the initial wheel speed difference based on the condition result; The operating condition is determined by braking-related signals. The maximum wheel speed is used as the reference for braking conditions and the minimum wheel speed is used as the reference for non-braking conditions. The initial wheel speed difference is calculated. S106, compare the wheel speed difference with the threshold value corresponding to the working condition result, and perform dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel; Under braking conditions, the locking threshold is compared with the slippage threshold. When the limit is exceeded, torque increase / decrease control is performed on the target wheel to obtain the corrected wheel speed difference. S108, calculate the confidence level of each wheel based on the corrected wheel speed difference and the initial wheel speed difference; That is, based on the corrected wheel speed difference (target wheel) and the initial wheel speed difference (non-target wheel), the confidence level of the four wheels is calculated through piecewise logic; S110 converts the linear velocity of each wheel into the corresponding longitudinal velocity component of the vehicle based on the positional relationship between the wheel and the vehicle's center of gravity. By combining the positional relationship between the wheel and the center of mass, the linear velocity of the wheel is converted into a longitudinal velocity component using a formula. S112, using the confidence level of each wheel as a weight, the longitudinal reference speed of the vehicle is obtained by weighted averaging.

[0025] The final longitudinal reference speed is calculated by weighting the confidence level.

[0026] In a preferred embodiment of practical application, abnormal wheel speeds are actively corrected by torque control, and valid data is filtered by confidence weighting to form a closed-loop estimation logic. This can overcome the limitation of existing technologies that only passively collect wheel speeds, actively improve the confidence of abnormal wheel speeds, and at the same time take into account the validity of all wheel data. This alleviates the core problem of inaccurate vehicle speed estimation when wheels slip / lock, and ensures reliable input for the vehicle stability controller.

[0027] For example, wheel speed acquisition and sorting are performed first: wheel speed sensors collect wheel speed signals from the four wheels of the vehicle—left front (FL), right front (FR), left rear (RL), and right rear (RR)—in real time. The sensors transmit the collected wheel speed data to the vehicle controller (VCU / ESC). After receiving the signals, the controller removes high-frequency noise and sorts the four wheel speeds from smallest to largest or from largest to smallest. Simultaneously, it outputs the sorted wheel speed data and the corresponding wheel identifiers, such as the minimum wheel speed. Maximum wheel speed This provides a benchmark for subsequent operating condition adaptation.

[0028] Next, the operating condition is determined and the initial wheel speed difference is calculated: The vehicle controller reads the brake pedal travel sensor signal or the brake system pressure signal to determine whether the vehicle is currently in a braking condition; if it is determined to be in a braking condition, the maximum wheel speed of the four wheels after sorting is used as the benchmark, combined with the vehicle's currently estimated initial longitudinal speed. Calculate the initial wheel speed difference; if it is determined to be a non-braking condition (including driving and coasting conditions), then use the minimum wheel speed of the four wheels after sorting as the benchmark, combined with the initial longitudinal vehicle speed. Calculate the initial wheel speed difference and the initial longitudinal vehicle speed. It is derived from the controller's historical calculation results or preset initial baseline values.

[0029] Next, threshold comparison and dynamic torque control are performed: the vehicle controller calls the preset threshold value corresponding to the operating condition, the locking threshold value corresponding to the braking condition, and the slippage threshold value corresponding to the non-braking condition. The calculated initial wheel speed difference is compared with the corresponding threshold value. If the difference does not exceed the threshold value, it means that the wheel has no obvious locking or slippage tendency, and no torque control is needed. The initial wheel speed difference is directly retained. If the difference exceeds the threshold value, dynamic torque control is performed on the target wheel - increasing torque on the specific wheel under braking condition and decreasing torque on the specific wheel under non-braking condition. After the control is completed, the corrected wheel speed difference value of the target wheel is obtained, and the initial wheel speed difference value is still used for the non-target wheels.

[0030] In addition, the confidence score for each wheel is calculated: For each wheel, the vehicle controller calculates the confidence score by matching a preset piecewise function based on its corresponding wheel speed difference type (corrected wheel speed difference for target wheels, initial wheel speed difference for non-target wheels). The smaller the wheel speed difference, the higher the confidence score; the larger the wheel speed difference, the lower the confidence score. This logic quantifies how close each wheel speed is to the actual vehicle speed, obtaining the confidence score data for each of the four wheels. .

[0031] Then, the wheel linear velocity and longitudinal velocity components are converted: the vehicle controller reads the vehicle yaw rate collected by the inertial measurement unit (IMU). The steering angle δ collected by the steering angle sensor, and the vehicle's preset front wheel track. Rear wheel track Using fixed parameters and the positional relationship between the wheels and the vehicle's center of gravity, the linear velocities of the front and rear wheels are converted using a specific formula. The linear velocity of each wheel (the target wheel is the corrected wheel velocity, and the non-target wheels are the original wheel velocity) is converted into a velocity component along the longitudinal direction (travel direction) of the vehicle.

[0032] Finally, the longitudinal reference speed is obtained by weighted averaging: the vehicle controller multiplies the confidence level of each of the four wheels by the corresponding longitudinal speed component, sums the products, and calculates the sum of the confidence levels of the four wheels. The sum of the products is then divided by the sum of the confidence levels to obtain the final longitudinal reference speed of the vehicle. This result is directly output to the stability controllers such as vehicle yaw control and drive anti-slip, as input parameters for the calculation of control targets, thus completing one speed estimation process.

[0033] In some embodiments, step S104 in the foregoing embodiments can calculate the initial wheel speed difference value according to different working conditions, including: If the vehicle is braking, the initial wheel speed difference is calculated based on the maximum wheel speed among the four wheels, using the following formula:

[0034] If the vehicle is not braking, the initial wheel speed difference is calculated based on the lowest wheel speed among the four wheels, using the following formula:

[0035] Research has revealed that when a vehicle is in driving mode, the wheels tend to slip, resulting in wheels with higher wheel speeds exhibiting abnormal slippage, while wheels with lower wheel speeds are closer to the actual longitudinal speed of the vehicle. Conversely, when a vehicle is braking, the wheels tend to lock, leading to wheels with lower wheel speeds exhibiting excessive locking, while wheels with higher wheel speeds are closer to the actual longitudinal speed of the vehicle. This invention, based on the core principle that wheels with higher wheel speeds are closer to the actual vehicle speed under braking conditions, and wheels with lower wheel speeds are closer to the actual vehicle speed under non-braking conditions, adapts specific wheel speed benchmarks for different operating conditions, achieving precise quantification of the initial wheel speed difference. This avoids the coarse logic of existing technologies that use a unified benchmark to calculate differences, ensuring that the initial wheel speed difference accurately reflects the degree of wheel locking or slippage, providing a reliable basis for subsequent torque control triggering and confidence level calculations.

[0036] For example, the vehicle operating condition is first determined: the vehicle controller receives signals from the brake pedal travel sensor or the brake system pressure sensor in real time. When the sensor detects that the brake pedal is pressed and the brake system pressure reaches a preset threshold, the vehicle is determined to be in braking condition. When no braking operation is detected and the brake system pressure is lower than the preset threshold, the vehicle is determined to be in non-braking condition. Non-braking condition includes driving condition when the vehicle is accelerating and coasting condition when the accelerator and brake pedals are not pressed.

[0037] Next, select the corresponding wheel speed reference: If the condition is determined to be braking, the vehicle controller extracts the maximum value from the four wheel speeds sorted in step one, i.e. The wheel speed corresponding to this maximum value is closest to the vehicle's actual longitudinal speed and is used as the wheel speed benchmark under braking conditions; if the condition is determined to be non-braking, the controller extracts the minimum value from the sorted four wheel speeds, i.e. The wheel speed corresponding to this minimum value is least affected by slippage and is closer to the actual vehicle speed, serving as a benchmark for wheel speed under non-braking conditions.

[0038] Finally, the initial wheel speed difference is calculated: the vehicle controller calls the current initial longitudinal vehicle speed. Under braking conditions, the initial wheel speed difference is calculated using the logic of initial longitudinal vehicle speed - maximum wheel speed of four wheels. Under non-braking conditions, the initial wheel speed difference is calculated using the logic of initial longitudinal vehicle speed - minimum wheel speed of four wheels. The initial longitudinal vehicle speed is the current vehicle speed estimated by the vehicle controller based on historical data, ensuring the consistency of the benchmark for the difference calculation. The calculation result is directly used for subsequent threshold value comparison.

[0039] Based on the aforementioned embodiments, step S106, when the vehicle is in braking condition, can be achieved through the following steps, including: Step 1.1: When the vehicle is in braking condition and the wheel speed difference exceeds the locking threshold, calculate the torque increase value based on the braking torque of each wheel. Here, we first determine whether the initial wheel speed difference under braking conditions exceeds the locking threshold, and then calculate it using the following formula: Increased torque value = wheel braking torque × calibration coefficient The calibration coefficient can be preset.

[0040] Step 1.2: Select the wheel with the lowest wheel speed and the diagonal wheel opposite the wheel with the lowest wheel speed, and perform torque increase control according to the torque increase value to correct the locking state of the target wheel and the wheel speed difference after correction. Here, the wheel with the lowest wheel speed and its diagonal wheel are selected to increase torque, correct the locking state, and obtain the corrected wheel speed difference; where the target wheels include the wheel with the lowest wheel speed and the diagonal wheel of the wheel with the lowest wheel speed.

[0041] This invention focuses on the core target of the wheel with the lowest wheel speed and its diagonal wheel under braking conditions. It quantifies the torque increase by multiplying the braking torque by a calibration coefficient, thereby achieving precise torque increase control. It specifically increases the wheel speed of the wheel with locking tendency, reduces the degree of wheel locking, and makes the target wheel speed closer to the actual vehicle speed. At the same time, it directly obtains the corrected wheel speed difference, providing accurate input for subsequent confidence calculation and avoiding interference from low-confidence data of locked wheels on the estimation results.

[0042] For example, the locking threshold value is first compared: the vehicle controller calls the preset locking threshold value (this value is a constant based on the vehicle's braking performance calibration and is used to determine the severity of the wheel locking tendency), and compares the initial wheel speed difference calculated under braking conditions with the locking threshold value; if the initial wheel speed difference value does not exceed the locking threshold value, it indicates that the wheel locking tendency is slight and no torque increase control is required, and the wheel speed difference value of the target wheel still uses the initial wheel speed difference value; if the initial wheel speed difference value exceeds the locking threshold value, it indicates that the wheel has a significant locking tendency and the torque increase control process needs to be initiated.

[0043] Next, the torque boosting value is calculated: The vehicle controller reads the current braking torque data of each wheel. This data is collected in real time by the braking system sensors and transmitted to the controller, reflecting the magnitude of the braking force currently applied to the wheel. The controller calls the preset calibration coefficient (this coefficient is a constant calibrated based on the vehicle's dynamic characteristics and is used to match the torque boosting demand with the wheel speed correction effect). Through the logic of torque boosting value = wheel braking torque × calibration coefficient, the required torque boosting torque for each target wheel is calculated, thus clarifying the quantitative standard for torque boosting control.

[0044] Next, the target wheel is selected and torque boosting control is executed: Based on the wheel speed sorting results in step one, the vehicle controller locates the wheel with the lowest wheel speed, and then, according to the diagonal distribution rules of the vehicle wheels (left front and right rear diagonal, right front and left rear diagonal), determines the diagonal wheel opposite the wheel with the lowest wheel speed. These two wheels are used as the target wheels for torque boosting control. The controller sends a torque boosting command to the hub motor or braking system corresponding to the target wheel, increases the torque of the target wheel according to the calculated torque boosting torque value, and relieves the wheel lock-up state by boosting torque, so that the wheel speed of the target wheel gradually increases and approaches the actual vehicle speed.

[0045] Finally, the corrected wheel speed difference is obtained: After the torque increase control is executed, the wheel speed sensor collects the corrected wheel speed of the target wheel in real time. The vehicle controller receives the corrected wheel speed data and, combined with the current initial longitudinal vehicle speed, recalculates the wheel speed difference of the target wheel. This difference is the corrected wheel speed difference, which is used for subsequent confidence calculation of the target wheel.

[0046] Based on the aforementioned embodiments, step S106, when the vehicle is in a non-braking condition, can be achieved through the following steps: Step 2.1: When the vehicle is in a non-braking condition and the wheel speed difference exceeds the slip threshold, calculate the torque reduction value based on the driving torque of each wheel. First, determine whether the initial wheel speed difference under non-braking conditions exceeds the slippage threshold, and then calculate it using the following formula: Reduced torque value = wheel drive torque × calibration coefficient Step 2.2: Select the wheel with the maximum wheel speed and the diagonal wheel opposite the wheel with the maximum wheel speed, and perform torque reduction control according to the torque reduction value to correct the slippage state of the target wheel and the wheel speed difference after correction. Here, the wheel with the highest wheel speed and the diagonal wheel are selected to reduce torque, correct the slippage state, and obtain the corrected wheel speed difference; where the target wheels include the wheel with the highest wheel speed and the diagonal wheel of the wheel with the highest wheel speed.

[0047] In non-braking conditions, this invention locks the wheel with the highest wheel speed and the diagonal wheel, which are prone to slippage. By quantifying the torque reduction through the concept of driving torque × calibration coefficient, precise torque reduction control is achieved. This effectively suppresses the artificially high wheel speed of slipping wheels, reduces the degree of wheel slippage, and makes the target wheel speed closer to the actual vehicle speed. At the same time, it generates a corrected wheel speed difference value, providing accurate input for subsequent confidence calculation and improving the reliability of vehicle speed estimation under non-braking conditions.

[0048] For example, the slippage threshold is first compared: the vehicle controller calls the preset slippage threshold (this value is a constant based on the vehicle's driving performance calibration, used to determine the severity of the wheel slippage trend), and compares the initial wheel speed difference calculated under non-braking conditions with the slippage threshold; if the initial wheel speed difference does not exceed the slippage threshold, it indicates that the wheel slippage trend is slight, and no torque reduction control is required, and the wheel speed difference of the target wheel still uses the initial wheel speed difference; if the initial wheel speed difference exceeds the slippage threshold, it indicates that the wheel has a significant slippage trend, and the torque reduction control process needs to be initiated.

[0049] Next, the torque reduction value is calculated: The vehicle controller reads the current driving torque data of each wheel. This data is collected in real time by the wheel hub motor torque sensor and transmitted to the controller, reflecting the current driving force output by the wheel hub motor to the wheel. The controller calls the preset calibration coefficient (this coefficient is a constant calibrated based on the vehicle dynamics characteristics and is used to match the torque reduction requirement with the wheel speed correction effect). Through the logic of torque reduction value = wheel driving torque × calibration coefficient, the required torque reduction value for each target wheel is calculated, and the quantitative standard of torque reduction control is clarified.

[0050] Next, the target wheel is selected and torque reduction control is executed: Based on the wheel speed sorting results in step one, the vehicle controller locates the wheel with the highest wheel speed, and then, according to the diagonal distribution rules of the vehicle wheels (left front and right rear diagonal, right front and left rear diagonal), determines the diagonal wheel of the wheel with the highest wheel speed, and uses these two wheels as the target wheels for torque reduction control; the controller sends a torque reduction command to the hub motor corresponding to the target wheel, and reduces the drive torque of the target wheel according to the calculated torque reduction torque value. By reducing torque, wheel slippage is suppressed, and the wheel speed of the target wheel gradually decreases and approaches the actual vehicle speed.

[0051] Finally, the corrected wheel speed difference is obtained: After the torque reduction control is executed, the wheel speed sensor collects the corrected wheel speed of the target wheel in real time. The vehicle controller receives the corrected wheel speed data and, combined with the current initial longitudinal vehicle speed, recalculates the wheel speed difference of the target wheel. This difference is the corrected wheel speed difference, which is used for subsequent confidence calculation of the target wheel.

[0052] In some embodiments, step S108 may be implemented by the following steps: Based on the preset threshold intervals where the corrected wheel speed difference and the initial wheel speed difference fall, select the corresponding piecewise function to calculate the confidence level of each wheel. The specific piecewise function is as follows:

[0053] The confidence level Q is calculated through a piecewise function, where the corrected rear wheel speed difference (target wheel) and the initial wheel speed difference (non-target wheel) are used as the input parameters x of the piecewise function respectively, and the corresponding function is selected to calculate the Q value according to the preset threshold intervals (x < a, a ≤ x < b, x ≥ b) where x is located.

[0054] The embodiment of the present invention adopts a quantization logic of a piecewise function adapted to the difference interval, distinguishes different input scenarios of the corrected and initial wheel speed differences, and realizes the accurate evaluation of the confidence level of all wheels; it can break through the limitation of the existing technology without a clear quantization standard for wheel speed reliability, enable the confidence level to objectively reflect the true reference value of the wheel speed, provide a scientific weight basis for subsequent weighted averaging, and improve the accuracy of vehicle speed estimation.

[0055] Exemplarily, first, preset the threshold intervals and piecewise functions: Three groups of preset threshold intervals are pre-stored in the vehicle controller, which are respectively that the wheel speed difference x is less than the constant a, the wheel speed difference x is greater than or equal to the constant a and less than the constant b, and the wheel speed difference x is greater than or equal to the constant b, where a and b are constants calibrated according to the vehicle wheel speed deviation characteristics and are used to divide the wheel speed reliability levels; at the same time, piecewise functions corresponding to the three intervals are pre-stored. The function of the first interval is the confidence level Q = 1 (the wheel speed is the most reliable), the function of the second interval is the confidence level (the confidence level decreases linearly), and the function of the third interval is the confidence level (the wheel speed is the least reliable), where is the preset minimum confidence level threshold, which is used to limit the lower limit of the confidence level.

[0056] Secondly, distinguish the types of wheel speed differences: The vehicle controller determines the corresponding wheel speed difference types for each of the four wheels one by one. If the wheel is the target wheel for torque control (the minimum wheel speed wheel and the diagonal wheel under braking conditions, the maximum wheel speed wheel and the diagonal wheel under non-braking conditions), the corrected rear wheel speed difference is selected as the input parameter; if the wheel is a non-target wheel (the wheel that does not execute torque control), the initial wheel speed difference is selected as the input parameter.

[0057] Finally, calculate the confidence level of each wheel: For each wheel, the vehicle controller judges the preset threshold interval where its input parameter (the corrected rear wheel speed difference or the initial wheel speed difference) is located, and selects the corresponding piecewise function to calculate the confidence level; for example, when the initial wheel speed difference of the non-target wheel , the confidence level Q = 1 is calculated through the function of the first interval; when the corrected rear wheel speed difference of the target wheel , the linearly decreasing confidence level is calculated through the function of the second interval; when the wheel speed difference , the confidence level is calculated through the function of the third interval, and finally the confidence level data of the four wheels are obtained respectively .

[0058] In practical applications, step S110 can be achieved through the following steps: By combining the vehicle's yaw rate, track width, and front wheel angle, the linear velocities of the front and rear wheels are adapted and converted to obtain the longitudinal velocity components of each wheel.

[0059] Here, through the front wheel conversion formula Rear wheel conversion formula Combined with the vehicle's yaw rate Front wheel track Rear wheel track Parameters such as the front wheel steering angle δ are used to convert the wheel linear velocity into a longitudinal velocity component.

[0060] This invention combines vehicle dynamic motion parameters (yaw rate, front wheel angle) and fixed structural parameters (wheelbase) to design a dedicated conversion formula for the front and rear wheels, correcting speed deviations caused by positional differences and motion states. It avoids the crude approach of directly equating wheel linear velocity with longitudinal vehicle speed in existing technologies, making the longitudinal velocity component of each wheel more closely match the actual motion state of the vehicle, and providing accurate basic data for the final weighted estimation.

[0061] For example, the parameters required for conversion are first collected: the vehicle controller receives data from various sensors in real time, including the vehicle yaw rate collected by the inertial measurement unit (IMU). (Unit: rad / s, angular velocity of rotation about the vertical axis of the vehicle's center of gravity, clockwise is positive), front wheel steering angle δ collected by the steering angle sensor (unit: rad, representing the front wheel deflection angle); simultaneously, the vehicle's preset fixed structural parameters, namely the front wheel track, are called up. (Unit: m, representing the horizontal distance between the centers of the left and right front wheels on the front axle) and rear wheel track. (Unit: m, representing the horizontal distance between the centers of the left and right rear wheels on the rear axle); In addition, the linear velocity of each wheel is obtained. (Unit: m / s, the target wheel is the corrected wheel speed, and the non-target wheel is the original wheel speed, which is obtained by the wheel speed sensor and converted. The conversion logic is: wheel linear speed = wheel speed × wheel rolling radius).

[0062] Next, the longitudinal velocity component conversion of the front wheels is performed: For the left front (FL) and right front (FR) wheels, a front-wheel-specific conversion formula is used for calculation. The ± sign in the formula is determined by the left and right positions of the wheels, with the left front wheel taking - and the right front wheel taking +. The conversion logic is as follows: First, the correction amount for the vehicle yaw on the linear velocity of the front wheels is calculated, i.e. This correction is used to compensate for the speed deviation caused by the different radii of the left and right front wheel trajectories during yaw motion; then, the wheel linear velocity is added to or subtracted from this correction to obtain the front wheel linear velocity after yaw correction; finally, it is multiplied by the cosine of the front wheel steering angle. The non-longitudinal wheel linear velocity projection after steering is decomposed into velocity components along the vehicle's longitudinal direction, namely the left front longitudinal velocity component. and right anterior longitudinal velocity component .

[0063] In addition, a longitudinal velocity component conversion of the rear wheels is performed: for the left rear (RL) and right rear (RR) wheels, a rear-wheel-specific conversion formula is used for calculation. The ± sign in the formula is determined by the left and right positions of the wheels, with the left rear wheel taking - and the right rear wheel taking +. Since the rear wheels do not participate in steering, no angle correction is required. The conversion logic is: only the correction amount of vehicle yaw on the linear velocity of the rear wheels is calculated. The longitudinal velocity component of the vehicle corresponding to the rear wheel is obtained by adding or subtracting the wheel linear velocity from the correction amount. This is the left rear longitudinal velocity component. and right rear longitudinal velocity component .

[0064] Finally, the longitudinal velocity components of the four wheels are output: the vehicle controller will calculate the longitudinal velocity components of the four wheels: front left, front right, rear left, and rear right. The data is stored and synchronized to the subsequent weighted calculation module as the basis for calculating the final reference vehicle speed.

[0065] Based on the aforementioned embodiments, step S112, which calculates the vehicle's longitudinal reference speed, includes: The longitudinal reference speed of the vehicle is obtained by multiplying the confidence level of each wheel by its corresponding longitudinal velocity component, summing the results, and then dividing by the sum of the confidence levels of each wheel.

[0066] The longitudinal reference vehicle speed is calculated using the following formula. :

[0067] The embodiments of this invention employ a confidence-weighted average logic, which gives a greater weight to wheels with high confidence (more reliable wheel speeds) in the final vehicle speed estimation, and a smaller weight to wheels with low confidence (large wheel speed deviations). This effectively weakens the interference of abnormal wheel speed data, strengthens the reference value of reliable wheel speed data, and significantly improves the accuracy and stability of longitudinal vehicle speed estimation compared to a simple arithmetic average.

[0068] For example, the basic calculation data is first retrieved: the vehicle controller retrieves the confidence data of the four wheels from the confidence calculation module, specifically the confidence of the left front wheel. Confidence level of the right front wheel Confidence level of the left rear wheel Confidence level of the right rear wheel Simultaneously, the longitudinal velocity components of the four wheels, namely the left front longitudinal velocity component, are retrieved from the speed conversion module. Right front longitudinal velocity component Left rear longitudinal velocity component Right rear longitudinal velocity component .

[0069] Next, the weighted product sum and the confidence sum are calculated: the vehicle controller calculates the weighted product of the four wheels separately according to the logic of each wheel's confidence score multiplied by the corresponding longitudinal velocity component. , , , Then, sum the four weighted product results to obtain the total weighted product; simultaneously, sum the four confidence scores to obtain the total confidence score. This ensures the integrity of the weighted calculation.

[0070] Finally, the longitudinal reference speed is calculated: the vehicle controller divides the weighted product sum by the confidence level sum to obtain the final longitudinal reference speed. For example, if a wheel has a confidence level of 1 (wheel speed is the most reliable), its longitudinal velocity component dominates the weighted calculation, while a confidence level of 1... The longitudinal velocity component of the wheel (which has the least reliable wheel speed) has minimal impact on the result; after calculation, the vehicle controller will use the longitudinal reference vehicle speed. The output is sent to the vehicle yaw control, drive anti-skid and other stability controllers as the core input parameters for the control target calculation, thus completing the vehicle speed estimation process.

[0071] Figure 2 A flowchart illustrating another method for estimating the longitudinal speed of a hub motor-driven vehicle, provided in an embodiment of the present invention.

[0072] Reference Figure 2 This method can also be implemented through the following steps: S1 sorts the four wheel speeds and outputs the sorted wheel speeds and the corresponding wheels. S2 determines whether the vehicle is in braking condition; If S3 is true, calculate the difference between the vehicle speed and the maximum wheel speed among the four wheel speeds; jump to S5 to determine if the wheel speed difference exceeds the locking threshold; if so, first execute S6 to calculate the required torque reduction value based on the braking torque of each wheel; S7 selects the wheel with the minimum wheel speed and its diagonal wheel for torque increase control; then jump to S11. Otherwise, proceed directly to execute S11; S11 Calculate the confidence level Q of the corresponding wheel based on the wheel speed difference; S12 Obtain the relationship between the wheel and the vehicle's center of gravity by analyzing the positional relationship between the wheel linear velocity and the vehicle's longitudinal velocity; S13 Obtain the reference vehicle speed by weighting the wheel linear velocity confidence factor Q as the weight. If S4 is not the case, calculate the difference between the vehicle speed and the minimum wheel speed among the four wheel speeds; jump to S8 to determine if the wheel speed difference exceeds the slip threshold. If so, execute S9 to calculate the required torque reduction value based on the braking torque of each wheel; S10 selects the wheel with the maximum wheel speed and its diagonal wheel for torque increase control; then jump to S11. Otherwise, proceed directly to execute S11; S11 Calculate the confidence level Q of the corresponding wheel based on the wheel speed difference; S12 Obtain the relationship between the wheel and the vehicle's center of gravity by considering the positional relationship between the wheel linear velocity and the vehicle's longitudinal velocity; S13 Obtain the reference vehicle speed by weighting the wheel linear velocity confidence factor Q as the weight.

[0073] In some embodiments, such as Figure 3 As shown, an embodiment of the present invention provides a longitudinal speed estimation device for a vehicle driven by a hub motor, comprising: The data acquisition module collects the wheel speeds of the vehicle's four wheels in real time, sorts them, and outputs the sorted wheel speeds and corresponding wheel identifiers. The first calculation module determines whether the vehicle is in braking condition and selects the corresponding wheel speed reference to calculate the initial wheel speed difference based on the condition result. The correction module compares the wheel speed difference with the threshold value corresponding to the working condition result, and performs dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel. The second calculation module calculates the confidence level of each wheel based on the corrected wheel speed difference and the initial wheel speed difference; The conversion module converts the linear velocity of each wheel into the corresponding longitudinal velocity component of the vehicle based on the positional relationship between the wheel and the vehicle's center of gravity. The weighting module uses the confidence level of each wheel as a weight to calculate the longitudinal reference speed of the vehicle.

[0074] This invention improves the accuracy of longitudinal vehicle speed by controlling the drive torque of the hub motor or increasing the braking torque of the wheel, thereby reducing the wheel speed of the slipping wheel or increasing the wheel speed of the locked wheel.

[0075] The present invention provides an embodiment of an electronic device. In this embodiment, the electronic device may be, but is not limited to, a personal computer (PC), a laptop computer, a monitoring device, a server, or other computer device with analysis and processing capabilities.

[0076] As an exemplary embodiment, see [reference]. Figure 4The electronic device 110 includes a communication interface 111, a processor 112, a memory 113, and a bus 114. The processor 112, the communication interface 111, and the memory 113 are connected via the bus 114. The memory 113 is used to store a computer program that supports the processor 112 in executing the above-described method. The processor 112 is configured to execute the program stored in the memory 113.

[0077] The machine-readable storage medium mentioned in this article can be any electronic, magnetic, optical, or other physical storage device that can contain or store information such as executable instructions, data, etc. For example, machine-readable storage media can be: RAM (Random Access Memory), volatile memory, non-volatile memory, flash memory, storage drives (such as hard disk drives), any type of storage disk (such as optical discs, DVDs, etc.), or similar storage media, or combinations thereof.

[0078] Non-volatile media can be non-volatile memory, flash memory, storage drives (such as hard disk drives), any type of storage disk (such as optical discs, DVDs, etc.), or similar non-volatile storage media, or combinations thereof.

[0079] It is understood that the specific operation methods of each functional module in this embodiment can be referred to the detailed description of the corresponding steps in the above method embodiment, and will not be repeated here.

[0080] The computer-readable storage medium provided in the embodiments of the present invention stores a computer program. When the computer program code is executed, it can implement the method described in any of the above embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0081] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0082] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0083] In the description of this invention, it should be noted that the terms center, up, down, left, right, vertical, horizontal, inner, and outer, indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms first, second, and third are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0084] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.

Claims

1. A method for estimating the longitudinal speed of a vehicle driven by a hub motor, characterized in that, include: Real-time acquisition and sorting of the vehicle's four wheel speeds, outputting the sorted wheel speeds and corresponding wheel identifiers; Determine whether the vehicle is in braking condition, and calculate the initial wheel speed difference based on the corresponding wheel speed reference. The wheel speed difference is compared with the threshold value corresponding to the working condition result, and the torque of the target wheel is dynamically controlled as needed to obtain the corrected wheel speed difference of the target wheel. The confidence level of each wheel is calculated based on the corrected wheel speed difference and the initial wheel speed difference. Based on the positional relationship between the wheels and the vehicle's center of gravity, the linear velocities of each wheel are converted into corresponding longitudinal velocity components of the vehicle. The longitudinal reference speed of the vehicle is obtained by weighting the confidence levels of each wheel.

2. The method according to claim 1, characterized in that, The step of determining whether the vehicle is in braking condition and selecting the corresponding wheel speed reference to calculate the initial wheel speed difference based on the condition result includes: If the vehicle is in braking condition, the initial wheel speed difference is calculated based on the maximum wheel speed among the four wheels. If the vehicle is not braking, the initial wheel speed difference is calculated based on the lowest wheel speed among the four wheels.

3. The method according to claim 1 or 2, characterized in that, The step of comparing the wheel speed difference with the threshold value corresponding to the working condition result, and performing dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel includes: When the vehicle is under braking and the wheel speed difference exceeds the locking threshold, the torque increase value is calculated based on the braking torque of each wheel. Select the wheel with the lowest wheel speed and the diagonal wheel opposite the wheel with the lowest wheel speed, and perform torque increase control according to the torque increase value to correct the locking state of the target wheel and the corrected wheel speed difference; the target wheel includes the wheel with the lowest wheel speed and the diagonal wheel opposite the wheel with the lowest wheel speed.

4. The method according to claim 1 or 2, characterized in that, The step of comparing the wheel speed difference with the threshold value corresponding to the working condition result, and performing dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel includes: When the vehicle is in a non-braking condition and the wheel speed difference exceeds the slippage threshold, the torque reduction value is calculated based on the driving torque of each wheel. Select the wheel with the maximum wheel speed and the diagonal wheel opposite the wheel with the maximum wheel speed, and perform torque reduction control according to the torque reduction value to correct the slippage state of the target wheel and the wheel speed difference after correction; the target wheel includes the wheel with the maximum wheel speed and the diagonal wheel opposite the wheel with the maximum wheel speed.

5. The method according to claim 1, characterized in that, The step of calculating the confidence level of each wheel based on the corrected wheel speed difference and the initial wheel speed difference includes: Based on the preset threshold intervals where the corrected wheel speed difference and the initial wheel speed difference are located, select the corresponding piecewise function to calculate the confidence level of each wheel.

6. The method according to claim 1, characterized in that, The step of converting the linear velocity of each wheel into a corresponding longitudinal velocity component of the vehicle based on the positional relationship between the wheel and the vehicle's center of gravity includes: By combining the vehicle's yaw rate, track width, and front wheel angle, the linear velocities of the front and rear wheels are adapted and converted to obtain the longitudinal velocity components of each wheel.

7. The method according to claim 1, characterized in that, The step of obtaining the vehicle's longitudinal reference speed by weighted averaging using the confidence levels of each wheel as weights includes: The longitudinal reference speed of the vehicle is obtained by multiplying the confidence level of each wheel by its corresponding longitudinal velocity component, summing the results, and then dividing by the sum of the confidence levels of each wheel.

8. A longitudinal speed estimation device for a vehicle driven by a hub motor, characterized in that, include: The data acquisition module collects the wheel speeds of the vehicle's four wheels in real time, sorts them, and outputs the sorted wheel speeds and corresponding wheel identifiers. The first calculation module determines whether the vehicle is in braking condition and selects the corresponding wheel speed reference to calculate the initial wheel speed difference based on the condition result. The correction module compares the wheel speed difference with the threshold value corresponding to the working condition result, and performs dynamic torque control on the target wheel as needed to obtain the corrected wheel speed difference of the target wheel. The second calculation module calculates the confidence level of each wheel based on the corrected wheel speed difference and the initial wheel speed difference; The conversion module converts the linear velocity of each wheel into the corresponding longitudinal velocity component of the vehicle based on the positional relationship between the wheel and the vehicle's center of gravity. The weighting module uses the confidence level of each wheel as a weight to calculate the longitudinal reference speed of the vehicle.

9. An electronic device, characterized in that, It includes a memory, a processor, and a program stored in the memory and capable of running on the processor, wherein the processor executes the program to implement the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The readable storage medium stores a computer program that, when executed, implements the method described in any one of claims 1-7.

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