Vehicle speed calculation methods, systems, and storage media

Abstract

This invention discloses a vehicle speed calculation method, comprising: calculating the corrected four-wheel wheel speeds based on the four-wheel wheel speeds and the vehicle's yaw rate; calculating the vehicle reference speed based on the corrected four-wheel wheel speeds and the presence of wheel-end braking force signals; calculating adaptive weights at different vehicle speeds; and calculating a corrected reference speed based on different acceleration decisions. This invention addresses the problems of vehicle speed calculation accuracy being easily affected by different road surface adhesion coefficients and actuator control performance, and the high cost and impracticality of existing commonly used speed estimation methods. It corrects the four-wheel wheel speeds using yaw rate, and then designs a vehicle speed reference value calculation method. By calculating adaptive weights at different vehicle speeds and combining them with different acceleration decisions to correct the vehicle speed reference value, the accuracy of vehicle speed estimation is improved, testing costs are reduced, and the accuracy of full-speed adaptive cruise control is further improved.

Description

Technical Field

[0001] This invention relates to the field of intelligent driving and ADAS for automobiles, and in particular to a method, system and storage medium for calculating vehicle speed. Background Technology

[0002] In recent years, with the upgrading of vehicle intelligent systems, ADAS, as a relatively cutting-edge system, has become a research subject for traditional vehicle manufacturers, emerging manufacturers, and academia. Among them, full-speed adaptive cruise control is a further functional upgrade based on traditional cruise control. It can enable vehicles to start and stop, cruise and follow other vehicles in all conditions on urban roads and highways, greatly reducing the driver's burden, improving fuel economy, and alleviating traffic pressure.

[0003] Accurate longitudinal speed of the vehicle is a key condition for achieving acceleration planning and precise control in adaptive cruise control systems. Adverse weather conditions (such as rain and snow), road conditions (such as potholes and muddy roads), and different vehicle actuator control performance can all affect the wheel speed of the four wheels, increasing the difficulty of estimating the vehicle's true speed and significantly impacting vehicle speed planning and dynamic control.

[0004] Existing methods for estimating vehicle longitudinal speed commonly include the maximum wheel speed method, the average wheel speed method, the slope method, and the Kalman filter method. However, while the maximum wheel speed method and the average wheel speed method can accurately calculate the actual vehicle speed when the tires are not slipping, they fail to do so when the tires are slipping. The slope method requires extensive experimentation to determine different initial vehicle velocities; any deviation between the road conditions / operating conditions and the map results in significant errors, making it impractical for engineering applications. The Kalman filter method requires a relatively accurate vehicle model, and obtaining the covariance matrix accurately is difficult, further limiting its practical applicability. Therefore, a more practical method for estimating vehicle longitudinal speed that can overcome the influence of different road surface adhesion coefficients is needed.

[0005] Chinese patent CN202211198114.2 provides a vehicle longitudinal speed control method, device, vehicle, and readable storage medium. This method acquires real-time vehicle attitude information, determines vehicle sway information based on the real-time attitude information, acquires vehicle wheel vibration information, acquires the number of wheel rotations and the distance traveled, determines the vehicle's slip ratio based on the number of wheel rotations and the distance traveled, and calculates the vehicle's longitudinal speed based on the sway information, vibration information, and slip ratio, thus controlling the vehicle to travel at the longitudinal speed. However, this solution calculates the vehicle's longitudinal speed based on the number of wheel rotations and the distance traveled. Although it considers the slip ratio, the actual slip ratio changes in real-time with factors such as speed, road friction, whether turning, and weather conditions, resulting in errors in the calculated longitudinal speed using a specific slip ratio.

[0006] Chinese patent CN202210979075.3 discloses a vehicle longitudinal speed tracking control method based on a UniTire tire model. First, a pure longitudinal slip characteristic test is conducted on a tire test bench, setting different tire operating parameters and recording the test data. The parameters of the tire model are fitted using the least squares method to obtain the UniTire tire model under pure longitudinal slip conditions. Then, based on the UniTire tire model under pure longitudinal slip conditions, a vehicle longitudinal speed control kinematic model is built. The desired longitudinal acceleration is solved by model predictive control and rolling optimization. Finally, a vehicle inverse dynamics transmission model and a drive / braking logic switching model are established. The desired longitudinal acceleration is used as the input to the inverse dynamics transmission model, and through power transmission and logic judgment, it is transformed into control of the engine throttle opening / brake master cylinder pressure. This scheme still calculates the vehicle's longitudinal speed based on the wheels, and the calculated vehicle longitudinal speed still has errors. Summary of the Invention

[0007] The summary of this invention introduces a series of simplified concepts, all of which are simplifications of existing technologies in the field, and will be further explained in detail in the detailed description section. This summary is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0008] The technical problem to be solved by the present invention is to provide a method and system for accurately calculating vehicle speed that is unaffected by the road surface adhesion coefficient and actuator control performance.

[0009] To solve the above-mentioned technical problems, the present invention provides a vehicle speed calculation method, which includes the following steps:

[0010] S1, calculate the corrected wheel speeds of the vehicle by performing wheel speed correction calculations based on the wheel speeds of the four wheels and the yaw rate of the vehicle.

[0011] S2, calculate the vehicle reference speed based on the signals of the corrected wheel speeds of the four wheels and the braking force at the wheel ends of the vehicle;

[0012] S3, calculate the adaptive weights at different vehicle speeds;

[0013] S4, calculates and corrects the reference vehicle speed based on different acceleration decisions.

[0014] Optionally, the vehicle speed calculation method, step S1 includes:

[0015] S1.1, Correct the wheel speeds of the four wheels of the vehicle based on the vehicle's yaw rate to obtain the corrected wheel speeds of the four wheels of the vehicle;

[0016] v′1=v1 / 3.6-γ×(π / 180)×d fr ×1 / 2 (1)

[0017] v′2=v2 / 3.6+γ×(π / 180)×d fr ×1 / 2 (2)

[0018] v′3=v3 / 3.6-γ×(π / 180)×d rr ×1 / 2 (3)

[0019] v′4=v4 / 3.6+γ×(π / 180)×d rr ×1 / 2 (4)

[0020] v1, v2, v3, v4 represent the wheel speeds of the vehicle's four wheels, γ represents the yaw rate, and d fr d rr These represent the wheelbase of the right front wheel and the wheelbase of the right rear wheel of the vehicle, respectively. v′1, v′2, v′3, and v′4 represent the corrected wheel speeds of the four wheels of the vehicle.

[0021] S1.2, Calculate the maximum and minimum values ​​of the four wheel speeds of the corrected vehicle to obtain the maximum reference speed v of the vehicle. slow and minimum value v fast .

[0022] Alternatively, in the vehicle speed calculation method, step S2 includes:

[0023] S2.1, when b exst When v = 1, ref =v fast When b exst When v = 0, ref =v slow ;

[0024] b exst This indicates that there is a signal of braking force at the wheel end.

[0025] Optionally, in the vehicle speed calculation method, step S3 includes:

[0026] S3.1, Construct the maximum reference speed v of the vehicle slow and minimum value v fas The switching strategy for t is O(k);

[0027]

[0028]

[0029] k represents the current time, k-1 represents the previous time, and O0 represents the initial value output by O(k);

[0030] S3.2, based on the switching strategy O(k) and the vehicle reference speed v ref Calculate up to v r ′ ef This serves as a speed reference value for subsequent weighting;

[0031]

[0032] ω represents the weighting factor, ranging from [0, 1]; v k_up The calibrated quantities were obtained based on real-vehicle testing experience;

[0033] S3.3, based on the corrected wheel speeds of the four wheels and the vehicle speed v′ ref Construct adaptive changing weight coefficients W i , for W i After averaging, the weighting coefficients α at different speeds are obtained. high and α low ;

[0034] λ i =(v′) i -v′ ref ) / v′ ref (10)

[0035]

[0036]

[0037] λ i This represents the proportionality constant, and different values ​​of α are obtained by calibrating different values ​​of k1 and k2. high and α low .

[0038] Optionally, in the vehicle speed calculation method, step S4 includes:

[0039] S4.1, Solve for the vehicle's reference acceleration 'a' using the vehicle's reference velocities at the current and previous moments. ref ;

[0040] S4.2, for the reference acceleration a ref The acceleration interval is denoted as τ. i ;

[0041]

[0042] L, M1, M2, and H represent interval symbols, with a value of a. ref The endpoints of the interval;

[0043] S4.3, based on the weighting coefficient α high α low and the wheel speed v′ of the four wheels i Solve for the speed value v at different vehicle reference speeds. w1 and v w2 When v ref >v k_up When using v w1 When v ref ≤v k_up When using v w2 ;

[0044]

[0045]

[0046] S4.4, according to different acceleration ranges τ i For the final vehicle speed v actual Perform calculations and allocation;

[0047]

[0048] To solve the above-mentioned technical problems, the present invention provides a computer-readable storage medium that stores a program internally, which, when executed, is used to implement the steps in the vehicle speed calculation method of any of the claims.

[0049] To solve the above-mentioned technical problems, the present invention provides a vehicle speed calculation system, comprising:

[0050] The correction unit calculates the corrected wheel speeds of the four wheels based on the wheel speeds and yaw rate of the vehicle.

[0051] The calculation unit calculates the vehicle reference speed based on the signals indicating the presence of corrected wheel speeds of the four wheels and the braking force at the wheel ends of the vehicle.

[0052] The weight calculation unit calculates adaptive weights at different vehicle speeds;

[0053] The correction unit calculates and corrects the reference vehicle speed based on different acceleration decisions.

[0054] Alternatively, the vehicle speed calculation system, in which the correction unit obtains the corrected wheel speeds of the four wheels of the vehicle using the following steps:

[0055] S1.1, Correct the wheel speeds of the four wheels of the vehicle based on the vehicle's yaw rate to obtain the corrected wheel speeds of the four wheels of the vehicle;

[0056] v′1=v1 / 3.6-γ×(π / 180)×d fr ×1 / 2 (1)

[0057] v′2=v2 / 3.6+γ×(π / 180)×d fr ×1 / 2 (2)

[0058] v′3=v3 / 3.6-γ×(π / 180)×d rr ×1 / 2 (3)

[0059] v′4=v4 / 3.6+γ×(π / 180)×d rr ×1 / 2 (4)

[0060] v1, v2, v3, v4 represent the wheel speeds of the vehicle's four wheels, γ represents the yaw rate, and d fr d rr These represent the wheelbase of the right front wheel and the wheelbase of the right rear wheel of the vehicle, respectively. v′1, v′2, v′3, and v′4 represent the corrected wheel speeds of the four wheels of the vehicle.

[0061] S1.2, Calculate the maximum and minimum values ​​of the four wheel speeds of the corrected vehicle to obtain the maximum reference speed v of the vehicle. slow and minimum value v fast .

[0062] Optionally, in the vehicle speed calculation system, the calculation unit calculates the vehicle reference speed using the following steps:

[0063] S2.1, when b exst When v = 1, ref =v fast When b exst When v = 0, ref =v slow ;

[0064] b exst This indicates that there is a signal of braking force at the wheel end.

[0065] Optionally, in the vehicle speed calculation system, the weight calculation unit calculates the adaptive weights for different vehicle speeds using the following steps:

[0066] S3.1, Construct the maximum reference speed v of the vehicle slow and minimum value v fas The switching strategy for t is O(k);

[0067]

[0068]

[0069] k represents the current time, k-1 represents the previous time, and O0 represents the initial value output by O(k);

[0070] S3.2, based on the switching strategy O(k) and the vehicle reference speed v ref Calculate up to v′ ref This serves as a speed reference value for subsequent weighting;

[0071]

[0072] ω represents the weighting factor, ranging from [0, 1]; v k_up The calibrated quantities were obtained based on real-vehicle testing experience;

[0073] S3.3, based on the corrected wheel speeds of the four wheels and the vehicle speed v′ ref Construct adaptive changing weight coefficients W i , for W i After averaging, the weighting coefficients α at different speeds are obtained. high and α low ;

[0074] λ i =(v′) i -v′ ref ) / v′ ref (10)

[0075]

[0076]

[0077] λ i This represents the proportionality constant, and different values ​​of α are obtained by calibrating different values ​​of k1 and k2. high and α low .

[0078] Optionally, in the vehicle speed calculation system, the correction unit calculates the corrected reference vehicle speed using the following steps:

[0079] S4.1, Solve for the vehicle's reference acceleration 'a' using the vehicle's reference velocities at the current and previous moments. ref ;

[0080] S4.2, for the reference acceleration a ref The acceleration interval is denoted as τ. i ;

[0081]

[0082] L, M1, M2, and H represent interval symbols, with a value of a. ref The endpoints of the interval;

[0083] S4.3, based on the weighting coefficient α high α low and the wheel speed v′ of the four wheels i Solve for the speed value v at different vehicle reference speeds. w1 and v w2 When v ref >v k_up When using v w1 When v ref ≤v k_up When using v w2 ;

[0084]

[0085]

[0086] S4.4, according to different acceleration ranges τ i For the final vehicle speed v actual Perform calculations and allocation;

[0087]

[0088] To eliminate the influence of road surface adhesion coefficient and actuator control performance, this invention calculates longitudinal vehicle speed from four aspects: four-wheel speed correction of yaw rate, calculation of vehicle speed reference value, calculation of adaptive weights at different vehicle speeds, and reference vehicle speed correction based on different acceleration decisions.

[0089] The four-wheel speed correction calculation based on yaw rate takes into account the yaw motion of the vehicle. The speed offset is calculated by the yaw rate of the vehicle. Then, combined with the actual motion state of the vehicle, the speed offset is subtracted or added to the four wheel speeds to solve for the corrected four-wheel speeds.

[0090] The vehicle speed reference value is calculated by taking into account tire slippage and vehicle safety during braking. This is achieved by taking the maximum and minimum values ​​of the corrected wheel speeds of the four wheels, respectively. These values ​​are then combined with the presence of braking signals to calculate the vehicle speed reference value. When wheel brakes are present, the maximum value of the four wheel speeds is used; when wheel brakes are absent, the minimum value is used.

[0091] The adaptive weight calculation at different vehicle speeds takes into account that the vehicle speed reference value calculated by the vehicle speed reference value calculation algorithm module may not be accurate, and it is necessary to overcome the jerking caused by the switching between the maximum and minimum vehicle speed values. A high speed reference threshold and a switching strategy for the maximum and minimum reference speed values ​​are designed. Then, a weight value allocation strategy is designed in combination with the corrected wheel speeds of the four wheels of the vehicle to obtain the weight values ​​at high speed and low speed respectively.

[0092] The reference speed correction calculation for different acceleration decisions takes into account vehicle safety and comfort. An acceleration range strategy is designed, and the vehicle speed reference value is allocated by combining the calculated weight values ​​of the vehicle at high and low speeds. Finally, filtering is performed to obtain the actual vehicle speed.

[0093] This invention addresses the problems of vehicle speed calculation accuracy being easily affected by different road surface adhesion coefficients and actuator control performance, as well as the high cost and impracticality of existing commonly used speed estimation methods. It provides a vehicle speed estimation method with strong engineering practicality and robustness. By correcting the wheel speeds of the four wheels through yaw rate, a vehicle speed reference value calculation method is designed. This method corrects the vehicle speed reference value by calculating adaptive weights at different vehicle speeds and combining them with different acceleration decisions. It avoids the shortcomings of existing techniques such as the maximum wheel speed method, average wheel speed method, slope method, and Kalman filtering method, improving the accuracy of vehicle speed estimation, reducing testing costs, and further improving the control accuracy of full-speed adaptive cruise control, thus demonstrating high practical engineering applicability. Attached Figure Description

[0094] The accompanying drawings are intended to illustrate the general characteristics of the methods, structures, and / or materials used in specific exemplary embodiments of the invention, supplementing the description in the specification. However, the drawings are schematic diagrams not drawn to scale and may not accurately reflect the precise structural or performance characteristics of any of the given embodiments. The drawings should not be construed as limiting or restricting the range of numerical values ​​or properties covered by exemplary embodiments of the invention. The invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0095] Figure 1 This is a calculation framework diagram of the vehicle speed calculation method of the present invention. Detailed Implementation

[0096] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can fully understand other advantages and technical effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific embodiments, and various details in this specification can also be applied based on different viewpoints, with various modifications or changes made without departing from the overall design concept of the invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. The following exemplary embodiments of the present invention can be implemented in many different forms and should not be construed as being limited to the specific embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of the present invention is thorough and complete, and that the technical solutions of these exemplary embodiments are fully conveyed to those skilled in the art. It should be understood that when an element is referred to as "connected" or "combined" to another element, the element can be directly connected or combined to the other element, or there may be intermediate elements. The difference is that when an element is referred to as "directly connected" or "directly combined" to another element, there are no intermediate elements. Throughout the drawings, the same reference numerals always denote the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0097] First embodiment;

[0098] refer to Figure 1 As shown, the present invention provides a method for calculating vehicle speed, comprising the following steps:

[0099] S1, calculate the corrected wheel speeds of the vehicle by performing wheel speed correction calculations based on the wheel speeds of the four wheels and the yaw rate of the vehicle.

[0100] S2, calculate the vehicle reference speed based on the signals of the corrected wheel speeds of the four wheels and the braking force at the wheel ends of the vehicle;

[0101] S3, calculate the adaptive weights at different vehicle speeds;

[0102] S4, calculates and corrects the reference vehicle speed based on different acceleration decisions.

[0103] The first implementation step S1 includes:

[0104] S1.1, Convert the units of the vehicle's four-wheel wheel speed and yaw rate to obtain the four-wheel wheel speed signal in m / s and the yaw rate in rad / s respectively;

[0105] The corrected four-wheel wheel speeds are obtained by calculating the vehicle's four-wheel wheel speeds and yaw rate after unit conversion.

[0106] v′1=v1 / 3.6-γ×(π / 180)×d fr ×1 / 2 (1)

[0107] v′2=v2 / 3.6+γ×(π / 180)×d fr ×1 / 2 (2)

[0108] v′3=v3 / 3.6-γ×(π / 180)×d rr ×1 / 2 (3)

[0109] v′4=v4 / 3.6+γ×(π / 180)×d rr ×1 / 2 (4)

[0110] v1, v2, v3, v4 represent the wheel speeds of the vehicle's four wheels, γ represents the yaw rate, and d fr d rr These represent the wheelbase of the right front wheel and the wheelbase of the right rear wheel of the vehicle, respectively. v′1, v′2, v′3, and v′4 represent the corrected wheel speeds of the four wheels of the vehicle.

[0111] S1.2, Calculate the maximum and minimum values ​​of the four wheel speeds of the corrected vehicle to obtain the maximum reference speed v of the vehicle. slow and minimum value v fast ;

[0112] v slow =min(v′1,v′2,v′3,v′4) (5)

[0113] v fast =max(v′1,v′2,v′3,v′4) (6).

[0114] Step S2 of the first implementation mentioned above includes:

[0115] S2.1, when b exst When v = 1, ref =v fast When b exst When v = 0, ref =v slow ;

[0116] b exst This indicates that there is a signal of braking force at the wheel end.

[0117] Step S3 of the first implementation mentioned above includes:

[0118] S3.1, combined with the presence of a signal b at the vehicle's wheel-end braking force. exst Design a strategy for switching between the maximum and minimum reference speeds, and construct the maximum reference speed v of the vehicle. slow and minimum value v fastThe switching strategy is O(k);

[0119]

[0120]

[0121] k represents the current time, k-1 represents the previous time, and O0 represents the initial value output by O(k);

[0122] S3.2, based on the switching strategy O(k) and the vehicle reference speed v ref Calculate up to v′ ref This serves as a speed reference value for subsequent weighting;

[0123]

[0124] ω represents the weighting factor, ranging from [0, 1]; v k_up The calibrated quantities were obtained based on real-vehicle testing experience;

[0125] S3.3, based on the corrected wheel speeds v′1, v′2, v′3, v′4 of the four wheels of the vehicle and the vehicle speed v′ ref Construct adaptive changing weight coefficients W i , for W i After averaging, the weighting coefficients α at different speeds are obtained. high and α low ;

[0126] λ i =(v′) i -v′ ref ) / v′ ref (10)

[0127]

[0128]

[0129] λ i This represents the proportionality constant, and different values ​​of α are obtained by calibrating different values ​​of k1 and k2. high and α low .

[0130] Step S4 of the first implementation mentioned above includes:

[0131] S4.1, Solve for the vehicle's reference acceleration 'a' using the vehicle's reference velocities at the current and previous moments. ref ;

[0132] v ref (k)=v ref (k-1)+a ref ·T (13)

[0133] T represents the controller's operating cycle;

[0134] S4.2, for the reference acceleration a ref The acceleration interval is denoted as τ. i ;

[0135]

[0136] L, M1, M2, and H represent interval symbols, with a value of a. ref The endpoints of the interval;

[0137] S4.3, based on the weighting coefficient α high α low and the wheel speed v′ of the four wheels i Solve for the speed value v at different vehicle reference speeds. w1 and v w2 When v ref >v k_up When using v w1 When v ref ≤v k_up When using v w2 ;

[0138]

[0139]

[0140] S4.4, according to different acceleration ranges τ i For the final vehicle speed v actua l performs calculations and allocation;

[0141]

[0142] Second embodiment;

[0143] The present invention provides a computer-readable storage medium having a program stored therein, which, when executed, is used to implement the steps in the vehicle speed calculation method of the first embodiment.

[0144] The computer-readable medium includes both permanent and non-permanent, removable and non-removable media, which can store information by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include non-transitory computer-readable media, such as modulated data signals and carrier waves.

[0145] Third embodiment;

[0146] This invention provides a vehicle speed calculation system, which can be implemented based on existing vehicle-mounted hardware and computer programming techniques, including:

[0147] The correction unit calculates the wheel speed correction based on the vehicle's four-wheel wheel speeds and yaw rate to obtain the corrected wheel speeds for the four wheels, including:

[0148] S1.1, Convert the units of the vehicle's four-wheel wheel speed and yaw rate to obtain the four-wheel wheel speed signal in m / s and the yaw rate in rad / s respectively;

[0149] The corrected four-wheel wheel speeds are obtained by calculating the vehicle's four-wheel wheel speeds and yaw rate after unit conversion.

[0150] v′1=v1 / 3.6-γ×(π / 180)×d fr ×1 / 2 (1)

[0151] v′2=v2 / 3.6+γ×(π / 180)×d fr ×1 / 2 (2)

[0152] v′3=v3 / 3.6-γ×(π / 180)×d rr ×1 / 2 (3)

[0153] v′4=v4 / 3.6+γ×(π / 180)×d rr ×1 / 2 (4)

[0154] v1, v2, v3, v4 represent the wheel speeds of the vehicle's four wheels, γ represents the yaw rate, and d fr d rr These represent the wheelbase of the right front wheel and the wheelbase of the right rear wheel of the vehicle, respectively. v′1, v′2, v′3, and v′4 represent the corrected wheel speeds of the four wheels of the vehicle.

[0155] S1.2, Calculate the maximum and minimum values ​​of the four wheel speeds of the corrected vehicle to obtain the maximum reference speed v of the vehicle. slow and minimum value v fast ;

[0156] v slow =min(v′1,v′2,v′3,v′4) (5)

[0157] v fast =max(v′1,v′2,v′3,v′4) (6).

[0158] The calculation unit calculates the vehicle reference speed based on the signals indicating the presence of corrected wheel speeds and wheel-end braking forces, including: when b exst When v = 1, ref =v fast When b exst When v = 0, ref =v slow b exst This indicates that there is a signal of braking force at the wheel end.

[0159] The weight calculation unit calculates adaptive weights at different vehicle speeds, including:

[0160] S3.1, combined with the presence of a signal b at the vehicle's wheel-end braking force. exst Design a strategy for switching between the maximum and minimum reference speeds, and construct the maximum reference speed v of the vehicle. slow and minimum value v fast The switching strategy is O(k);

[0161]

[0162]

[0163] k represents the current time, k-1 represents the previous time, and O0 represents the initial value output by O(k);

[0164] S3.2, based on the switching strategy O(k) and the vehicle reference speed v ref Calculate up to v r ′ ef This serves as a speed reference value for subsequent weighting;

[0165]

[0166] ω represents the weighting factor, ranging from [0, 1]; v k_up The calibrated quantities were obtained based on real-vehicle testing experience;

[0167] S3.3, based on the corrected wheel speeds v′1, v′2, v′3, v′4 of the four wheels of the vehicle and the vehicle speed v′ ref Construct adaptive changing weight coefficients W i , for W i After averaging, the weighting coefficients α at different speeds are obtained. high and α low ;

[0168] λ i =(v′) i -v′ ref ) / v′ ref (10)

[0169]

[0170]

[0171] λ i This represents the proportionality constant, and different values ​​of α are obtained by calibrating different values ​​of k1 and k2. high and α low .

[0172] The correction unit, which calculates and corrects the reference vehicle speed based on different acceleration decisions, includes:

[0173] S4.1, Solve for the vehicle's reference acceleration 'a' using the vehicle's reference velocities at the current and previous moments. ref ;

[0174] v ref (k)=v ref (k-1)+a ref ·T (13)

[0175] T represents the controller's operating cycle;

[0176] S4.2, for the reference acceleration a ref The acceleration interval is denoted as τ. i ;

[0177]

[0178] L, M1, M2, and H represent interval symbols, with a value of a. ref The endpoints of the interval;

[0179] S4.3, based on the weighting coefficient α high α low and the wheel speed v′ of the four wheelsi Solve for the speed value v at different vehicle reference speeds. w1 and v w2 When v ref >v k_up When using v w1 When v ref ≤v k_up When using v w2 ;

[0180]

[0181]

[0182] S4.4, according to different acceleration ranges τ i For the final vehicle speed v actual Perform calculations and allocation;

[0183]

[0184] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will also be understood that, unless expressly defined herein, terms such as those defined in a general dictionary shall be interpreted as having the meaning consistent with their meaning in the relevant field context, and not as having an idealized or overly formal meaning.

[0185] The present invention has been described in detail above through specific embodiments and examples, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for calculating vehicle speed, characterized in that, Includes the following steps: S1, calculates the corrected wheel speeds based on the vehicle's four-wheel wheel speeds and yaw rate, including: S1.1, Correct the wheel speeds of the four wheels of the vehicle based on the vehicle's yaw rate to obtain the corrected wheel speeds of the four wheels of the vehicle; (1)； (2)； (3)； (4)； This indicates the speed of the vehicle's four wheels. Indicates yaw rate. These represent the wheelbase of the vehicle's right front wheel and the wheelbase of its right rear wheel, respectively. This indicates a correction of the wheel speeds of the vehicle's four wheels; S1.2, Take the maximum and minimum values ​​of the four wheel speeds of the corrected vehicle to obtain the maximum reference speed of the vehicle. and minimum value ; S2, calculate the vehicle reference speed based on the signals indicating the presence of corrected wheel speeds and wheel-end braking forces, including: S2.1, when hour, ;when hour, ; This indicates that there is a signal of braking force at the wheel end; S3 calculates the adaptive weights at different vehicle speeds, including: S3.1, Construct the maximum reference speed for the vehicle and minimum value Switching strategy ; （7）; （8）; Indicates the current moment. Indicates the previous moment, Indicates the process The initial value of the output; S3.2, according to the switching strategy and vehicle reference speed Calculated to This serves as a speed reference value for subsequent weighting; （9）; This represents the weighting factor, which ranges from [0, 1]. The calibrated quantities were obtained based on real-vehicle testing experience; S3.3, based on correcting the wheel speeds of the four wheels and the vehicle speed. Constructing adaptive changing weight coefficients ,right The weighting coefficients for different speeds were obtained by averaging. and ; (10)； (11)； (12)； This represents the proportionality coefficient, determined by different calibration values. and Get different and ; S4, calculates and corrects the reference vehicle speed based on different acceleration decisions.

2. The vehicle speed calculation method as described in claim 1, characterized in that, Step S4 includes: S4.1, Solve for the vehicle's reference acceleration using the vehicle's reference velocities at the current and previous moments. ; S4.2, for reference acceleration The acceleration interval is denoted as ; （14）； Indicates the interval symbol, with values ​​ranging from 1 to 2. The endpoints of the interval; S4.3, based on weighting coefficients and four-wheel speed Solve for the speed values ​​at different vehicle reference speeds. and ,when When using ;when When using ; （15）； （16）； S4.4, according to different acceleration ranges For the final vehicle speed Perform calculations and allocation; （17）。 3. A computer-readable storage medium, characterized in that: It internally stores a program that, when executed, implements the steps in the vehicle speed calculation method according to any one of claims 1-2.

4. A vehicle speed calculation system, characterized in that, include: The correction unit calculates the corrected wheel speeds of the four wheels based on the wheel speeds and yaw rate of the vehicle. The correction unit uses the following steps to obtain the corrected wheel speeds of the four wheels of the vehicle: S1.1, Correct the wheel speeds of the four wheels of the vehicle based on the vehicle's yaw rate to obtain the corrected wheel speeds of the four wheels of the vehicle; (1)； (2)； (3)； (4)； This indicates the speed of the vehicle's four wheels. Indicates yaw rate. These represent the wheelbase of the vehicle's right front wheel and the wheelbase of its right rear wheel, respectively. This indicates a correction of the wheel speeds of the vehicle's four wheels; S1.2, Take the maximum and minimum values ​​of the four wheel speeds of the corrected vehicle to obtain the maximum reference speed of the vehicle. and minimum value ; The calculation unit calculates the vehicle reference speed based on the signals indicating the presence of corrected wheel speeds of the four wheels and the braking force at the wheel ends of the vehicle. The calculation unit uses the following steps to calculate the vehicle reference speed: S2.1, when hour, ;when hour, ; This indicates that there is a signal of braking force at the wheel end; The weight calculation unit calculates the adaptive weights at different vehicle speeds using the following steps: S3.1, Construct the maximum reference speed for the vehicle and minimum value Switching strategy ; （7）; （8）; Indicates the current moment. Indicates the previous moment, Indicates the process The initial value of the output; S3.2, according to the switching strategy and vehicle reference speed Calculated to This serves as a speed reference value for subsequent weighting; （9）; This represents the weighting factor, which ranges from [0, 1]. The calibrated quantities were obtained based on real-vehicle testing experience; S3.3, based on correcting the wheel speeds of the four wheels and the vehicle speed. Constructing adaptive changing weight coefficients ,right The weighting coefficients for different speeds were obtained by averaging. and ; (10)； (11)； (12)； This represents the proportionality coefficient, determined by different calibration values. and Get different and ; The correction unit calculates and corrects the reference vehicle speed based on different acceleration decisions.

5. The vehicle speed calculation system as described in claim 4, characterized in that, The correction unit calculates the corrected reference vehicle speed using the following steps: S4.1, Solve for the vehicle's reference acceleration using the vehicle's reference velocities at the current and previous moments. ; S4.2, for reference acceleration The acceleration interval is denoted as ; （14）； Indicates the interval symbol, with values ​​ranging from 1 to 2. The endpoints of the interval; S4.3, based on weighting coefficients and four-wheel speed Solve for the speed values ​​at different vehicle reference speeds. and ,when When using ;when When using ; （15）； （16）； S4.4, according to different acceleration ranges For the final vehicle speed Perform calculations and allocation; （17）。

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