Transmission ratio determination method for steer-by-wire system based on cuckoo algorithm

Abstract

This application discloses a method for determining the transmission ratio of a steer-by-wire system based on the Cuckoo Algorithm, relating to the field of electric vehicle steering control technology. The method includes: acquiring vehicle operating data; obtaining the front wheel steady-state yaw rate gain value and vehicle stability evaluation index value; obtaining the maximum transmission ratio, minimum transmission ratio, and transmission ratio variation range; obtaining a transmission ratio surface plot; based on the Cuckoo Algorithm and vehicle stability evaluation index value, obtaining the target steering wheel steady-state yaw rate gain value and target center ratio corresponding to each speed segment; and smoothing the data to obtain the target transmission ratio surface plot. This application addresses the problems of poor smoothness and accuracy in determining the transmission ratio of steer-by-wire systems in existing technologies, improving the smoothness and accuracy of transmission ratio determination, thereby enhancing vehicle driving stability and driving comfort.

Description

Technical Field

[0001] This application relates to the field of electric vehicle steering control technology, and in particular to a method for determining the transmission ratio of a steer-by-wire system based on the Cuckoo algorithm. Background Technology

[0002] In recent years, the rapid development of the electric vehicle industry has led to an increased demand for advanced driver assistance systems (ADAS), with vehicle stability being particularly crucial. In traditional vehicles, the steering system relies on a fixed mechanical transmission ratio, which limits the vehicle's ability to adjust performance at different speeds, making it difficult to simultaneously meet the demands for sensitivity at low speeds and stability at high speeds. In contrast, the steer-by-wire system used in electric vehicles eliminates the physical connection between the steering wheel and the steering wheels, employing an electronic control system for steering.

[0003] Among them, steer-by-wire is an advanced automotive steering technology that controls the vehicle's steering through electronic signals, rather than traditional mechanical or hydraulic connections. Steer-by-wire systems can autonomously design their gear ratios, improving vehicle stability and driving comfort under various driving conditions. Therefore, the optimization and adjustment of gear ratios plays a crucial role in the design of steer-by-wire systems and has become a key direction in electric vehicle steering technology research.

[0004] In existing technologies, the design of the variable angle transmission ratio of the steer-by-wire system adopts fuzzy control or an ideal transmission ratio that is not affected by the steering wheel angle. However, the smoothness and accuracy of the transmission ratio of this design are poor, which leads to poor vehicle stability and a poor driving comfort experience. Summary of the Invention

[0005] To address the aforementioned problems and technical requirements, the applicant proposes a method for determining the transmission ratio of a steer-by-wire system based on the Cuckoo algorithm. This method aims to solve the problems of poor smoothness and accuracy in determining the transmission ratio of a steer-by-wire system in existing technologies, thereby improving the smoothness and accuracy of the determined transmission ratio and thus enhancing vehicle driving stability and comfort.

[0006] This application provides a method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm, including:

[0007] Obtain vehicle operating data;

[0008] Based on the aforementioned operational data, the front wheel steady-state yaw rate gain value and vehicle stability evaluation index value are obtained.

[0009] Based on the front wheel steady-state yaw rate gain value and the assumed steering wheel steady-state yaw rate gain value, the maximum transmission ratio and the minimum transmission ratio are obtained, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, the transmission ratio variation range is obtained.

[0010] Based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, and the operating data, a transmission ratio surface diagram is obtained;

[0011] Based on the Cuckoo algorithm and the vehicle stability evaluation index, the steady-state yaw rate gain value of the steering wheel and the center ratio corresponding to each speed segment are optimized to obtain the target steady-state yaw rate gain value of the steering wheel and the target center ratio corresponding to each speed segment. The speed segment is divided based on the vehicle speed.

[0012] The target steering wheel steady-state yaw rate gain value and the target center ratio are smoothed to obtain a target transmission ratio surface plot, wherein the target transmission ratio surface plot is used to characterize the correspondence between the motion data and the transmission ratio.

[0013] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm, the maximum transmission ratio and the minimum transmission ratio are obtained based on the steady-state yaw rate gain value of the front wheels and the assumed steady-state yaw rate gain value of the steering wheel. Furthermore, based on the maximum transmission ratio, the minimum transmission ratio, and the assumed center ratio, the transmission ratio variation range is obtained, including:

[0014] Based on the front wheel steady-state yaw rate gain value, the assumed steering wheel steady-state yaw rate gain value, and the preset maximum transmission ratio calculation formula, the maximum transmission ratio is obtained;

[0015] The formula for calculating the maximum transmission ratio includes:

[0016]

[0017] Among them, H high G represents the maximum transmission ratio. sw This represents the steady-state yaw rate gain of the steering wheel, v. x L represents the longitudinal velocity of the vehicle, L represents the sum of the distances from the front wheels to the center of gravity and the distances from the rear wheels to the center of gravity, and K represents the vehicle stability coefficient, which is a constant.

[0018] The minimum transmission ratio is obtained based on the minimum transmission ratio calculation formula;

[0019] The formula for calculating the minimum transmission ratio includes:

[0020]

[0021] Among them, H low G represents the minimum transmission ratio. fL This represents the minimum value of the front wheel steady-state yaw rate gain.

[0022] Based on the maximum transmission ratio, the minimum transmission ratio, the assumed center ratio, and the preset transmission ratio variation range calculation formula, the transmission ratio variation range is obtained;

[0023] The formula for calculating the range of transmission ratio variation includes:

[0024]

[0025] Where H represents the range of transmission ratio variation, σ represents the center ratio, and normpdf represents the normal probability density function.

[0026] According to an embodiment of this application, a method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm is used to obtain a transmission ratio surface diagram based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, and the operating data, including:

[0027] The transmission ratio surface diagram is obtained based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, the operating data, and the preset surface diagram calculation formula.

[0028] The surface plot calculation formula includes:

[0029] i = H·normpdf(δ) sw ,0,σ)+H low ;

[0030] Where i represents the transmission ratio, δ sw Indicates the steering wheel angle.

[0031] According to an embodiment of the present application, a method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm optimizes the steady-state yaw rate gain value of the steering wheel and the center ratio for each speed segment based on the cuckoo algorithm and the vehicle stability evaluation index value, to obtain the target steady-state yaw rate gain value of the steering wheel and the target center ratio for each speed segment, including:

[0032] The following determination process is performed for the steady-state yaw rate gain and center ratio of the steering wheel corresponding to each speed segment:

[0033] Based on the Cuckoo algorithm, the steady-state yaw rate gain value of the steering wheel and the center ratio are set as the bird's nest; based on Levi's flight, a new steady-state yaw rate gain value of the steering wheel and a new center ratio are obtained; the steady-state yaw rate gain value of the steering wheel and the new steady-state yaw rate gain value of the steering wheel, as well as the center ratio and the new center ratio, are compared; based on the vehicle stability evaluation index value corresponding to the speed segment, the health of the steady-state yaw rate gain value of the steering wheel and the center ratio is determined, and when the number of iterations reaches a preset number, the steady-state yaw rate gain value of the steering wheel corresponding to the highest health is determined as the target steady-state yaw rate gain value of the steering wheel, and the center ratio corresponding to the highest health is determined as the target center ratio.

[0034] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm of this application, the vehicle stability evaluation index value is obtained based on the operating data, including:

[0035] The vehicle stability evaluation index value is obtained based on the vehicle stability evaluation formula;

[0036] The vehicle stability evaluation formula includes:

[0037]

[0038] Where J represents the vehicle stability evaluation index value, J E w represents the trajectory tracking metric value. E J represents the weighted value of the trajectory tracking index, which is a constant. B This indicates the value of the manipulation burden indicator, w B J represents the weighted value of the manipulation burden index, which is a constant. R This represents the rollover index value, w R J represents the weighted value of the rollover metric. S This represents the sideslip index value, w S This represents the weighted value of the sideslip index, which is a constant.

[0039] The trajectory tracking index value is calculated based on the total vehicle driving time, actual driving path, vehicle longitudinal speed, and vehicle center of gravity offset angular velocity; the handling load index value is calculated based on steering wheel acceleration and steering wheel torque; the rollover index value is calculated based on lateral acceleration and roll angle; and the sideslip index value is calculated based on the lateral force on the front axle, front axle load, lateral force on the rear axle, and rear axle load.

[0040] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm of this application, the trajectory tracking index value is calculated based on the total vehicle travel time, the actual travel path, the vehicle's longitudinal speed, and the vehicle's center of gravity offset angular velocity, including:

[0041] The total driving time of the vehicle and the actual driving route are input into a preset path error calculation formula to obtain the path error output by the path error calculation formula.

[0042] The path error calculation formula includes:

[0043]

[0044] Among them, J e1 t represents the path error. n Let represent the total travel time, f(t) represent the desired path, and y(t) represent the actual travel path. This represents the standard value of the trajectory error, which is a constant.

[0045] The vehicle bus speed and the vehicle center of gravity offset angular velocity are input into a preset direction error calculation formula to obtain the direction error output by the direction error calculation formula.

[0046] The formula for calculating the direction error includes:

[0047]

[0048] Among them, J e2 Indicates directional error, v x (t) represents the longitudinal velocity of the vehicle at time t. This represents the angular velocity of the vehicle's center of gravity at time t. This represents the standard value of the vehicle's center of gravity offset angular acceleration, which is a constant.

[0049] The path error and the direction error are input into a preset trajectory tracking calculation formula to obtain the trajectory tracking index value output by the trajectory tracking calculation formula.

[0050] The trajectory tracking calculation formula includes:

[0051]

[0052] Among them, J E w represents the trajectory tracking metric value. e1 The weighted value representing the path error is a constant, w. e2 The weighted value representing the direction error is a constant.

[0053] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm of this application, the steering load index value is calculated based on the steering wheel acceleration and steering wheel torque, including:

[0054] The steering wheel acceleration is input into a preset busyness calculation formula to obtain the busyness level output by the busyness calculation formula;

[0055] The formula for calculating the busyness level includes:

[0056]

[0057] Among them, J b1 t indicates the level of busyness n This indicates the total travel time of the vehicle. This represents the acceleration of the steering wheel at time t. This represents the standard value of steering wheel acceleration, which is a constant.

[0058] The steering wheel torque is input into a preset weight calculation formula to obtain the weight output by the weight calculation formula;

[0059] The formula for calculating the weight includes:

[0060]

[0061] Among them, J b2 Indicating degree of weight, T sw (t) represents the steering wheel torque at time t. This represents the standard value of steering wheel torque, which is a constant.

[0062] Input the busyness level and the heaviness level into a preset operation burden calculation formula to obtain the operation burden index value output by the operation burden calculation formula;

[0063] The formula for calculating the manipulation burden includes:

[0064]

[0065] Among them, J B This indicates the value of the manipulation burden indicator, w b1 The weighted value representing the level of busyness is a constant, w. b2 The weighted value representing the degree of heaviness is a constant.

[0066] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm of this application, the rollover index value is calculated based on lateral acceleration and roll angle, including:

[0067] The lateral acceleration is input into a preset lateral acceleration calculation formula to obtain the lateral acceleration output by the lateral acceleration calculation formula.

[0068] The formula for calculating the lateral acceleration includes:

[0069]

[0070] Among them, J r1 Indicates lateral acceleration, t n Indicates the total travel time of the vehicle, a y (t) represents the lateral acceleration at time t. This represents the standard value of lateral acceleration, which is a constant.

[0071] Input the roll angle into the preset roll condition calculation formula to obtain the roll condition output by the roll condition calculation formula;

[0072] The formula for calculating the roll condition includes:

[0073]

[0074] Among them, J r2 This indicates the roll condition, where φ(t) represents the roll angle at time t. This represents the standard value of the roll angle, which is a constant.

[0075] The lateral acceleration and lateral tilt conditions are input into a preset rollover risk calculation formula to obtain the rollover index value output by the rollover risk calculation formula.

[0076] The formula for calculating rollover risk includes:

[0077]

[0078] Among them, J R J represents the rollover index value. r2 The weighted value representing lateral acceleration is a constant, w. r2 The weighted value representing the roll condition is a constant.

[0079] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm of this application, the sideslip index value is calculated based on the lateral force on the front axle, the front axle load, the lateral force on the rear axle, and the rear axle load, including:

[0080] Input the lateral force and load on the front axle into a preset front axle sideslip risk calculation formula to obtain the front axle sideslip risk value output by the front axle sideslip risk calculation formula;

[0081] The formula for calculating the risk of front axle sideslip includes:

[0082]

[0083] Where J1 represents the front axle sideslip risk value, t n F represents the total driving time of the vehicle. y1 (t) represents the lateral force F acting on the front axle at time t. z1(t) represents the front axle load at time t. This represents the lateral adhesion coefficient, which is a constant.

[0084] Input the lateral force and load on the rear axle into a preset rear axle sideslip risk calculation formula to obtain the rear axle sideslip risk value output by the rear axle sideslip risk calculation formula;

[0085] The formula for calculating the risk of rear axle sideslip includes:

[0086]

[0087] Where J2 represents the rear axle sideslip risk value, F y2 (t) represents the lateral force F acting on the rear axle at time t. z2 (t) represents the rear axle load at time t. This represents the lateral adhesion coefficient, which is a constant.

[0088] Input the front axle sideslip hazard value and the rear axle sideslip hazard value into a preset sideslip hazard calculation formula to obtain the sideslip index value output by the sideslip hazard calculation formula;

[0089] The formula for calculating the risk of sideslip includes:

[0090] J S =max(J1,J2);

[0091] Among them, J S This indicates the sideslip index value.

[0092] According to an embodiment of the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm of this application, the method obtains the front wheel steady-state yaw rate gain value based on the operating data, including:

[0093] Input the vehicle's longitudinal velocity into the gain value calculation formula to obtain the front wheel steady-state yaw rate gain value output by the gain value calculation formula;

[0094] The formula for calculating the gain value includes:

[0095]

[0096] Among them, G f This represents the steady-state yaw rate gain of the front wheels, v. x Let L represent the vehicle's longitudinal velocity, L represent the sum of the distances from the front wheels to the center of gravity and the distances from the rear wheels to the center of gravity, and K represent the vehicle's stability coefficient, which is a constant.

[0097] The transmission ratio determination method for a steer-by-wire system based on the Cuckoo algorithm provided in this application links the steering wheel angle with the transmission ratio. It designs a variable-angle transmission ratio based on a normal function related to vehicle speed and steering wheel angle, ensuring smoother steering and better obstacle avoidance capabilities. Furthermore, the Cuckoo optimization algorithm is used to optimize the steady-state gain and center ratio of the steering wheel, enhancing the vehicle's steering ability and ensuring smoother steering with better obstacle avoidance, thereby improving handling performance across various speed ranges. Additionally, vehicle speed is segmented to reduce driver workload. This application achieves smoothness of the transmission ratio surface, improving the smoothness and accuracy of transmission ratio determination, further enhancing vehicle stability, and reducing driver workload and driving comfort. Attached Figure Description

[0098] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0099] Figure 1 This is one of the flowcharts illustrating the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm provided in this application embodiment;

[0100] Figure 2 This is the second flowchart illustrating the method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm provided in this application embodiment;

[0101] Figure 3 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0102] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0103] This application provides a method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm. This method can be applied to smart terminals and servers. Other descriptions in the embodiments of this application are illustrative and not intended to limit the scope of protection of this application, and will not be described in detail thereafter. The specific implementation of the method is as follows: Figure 1 As shown:

[0104] Step 101: Obtain vehicle operating data.

[0105] The operational data includes: vehicle longitudinal speed, center of gravity offset angle, roll angle, yaw rate, front wheel angle, steering wheel angle, total vehicle driving time, actual driving path, vehicle center of gravity offset angular velocity, steering wheel acceleration, steering wheel torque, lateral acceleration, lateral force on the front axle, front axle load, lateral force on the rear axle, rear axle load, and steering wheel angular velocity.

[0106] Specifically, operational data can be collected using devices such as cameras, millimeter-wave radar, and sensors.

[0107] Step 102: Based on the operating data, obtain the front wheel steady-state yaw rate gain value and the vehicle stability evaluation index value.

[0108] Step 103: Based on the front wheel steady-state yaw rate gain value and the assumed steering wheel steady-state yaw rate gain value, obtain the maximum transmission ratio and the minimum transmission ratio, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, obtain the transmission ratio variation range.

[0109] Step 104: Based on the transmission ratio variation range, minimum transmission ratio, assumed center ratio, and operating data, obtain the transmission ratio surface diagram.

[0110] Step 105: Based on the Cuckoo algorithm and vehicle stability evaluation index, optimize the steady-state yaw rate gain and center ratio of the steering wheel for each speed segment to obtain the target steady-state yaw rate gain and target center ratio of the steering wheel for each speed segment.

[0111] The speed range is determined based on the vehicle's speed.

[0112] Step 106: Smooth the target steering wheel steady-state yaw rate gain and the target center ratio to obtain the target transmission ratio surface diagram.

[0113] The target gear ratio surface plot is used to characterize the correspondence between motion data and gear ratio. Specifically, it is used to characterize the correspondence between steering wheel angle and gear ratio.

[0114] Specifically, by smoothly transitioning the target transmission ratio surface diagram between each speed segment, the target transmission ratio surface diagram for the entire road segment can be obtained, which varies with vehicle speed and cable reel rotation angle.

[0115] The transmission ratio determination method for a steer-by-wire system based on the Cuckoo algorithm provided in this application links the steering wheel angle with the transmission ratio. It designs a variable-angle transmission ratio based on a normal function related to vehicle speed and steering wheel angle, ensuring smoother steering and better obstacle avoidance capabilities. Furthermore, the Cuckoo optimization algorithm is used to optimize the steady-state gain and center ratio of the steering wheel, enhancing the vehicle's steering ability and ensuring smoother steering with better obstacle avoidance, thereby improving handling performance across various speed ranges. Additionally, vehicle speed is segmented to reduce driver workload. This application achieves smoothness of the transmission ratio surface, improving the smoothness and accuracy of transmission ratio determination, further enhancing vehicle stability, and reducing driver workload and driving comfort.

[0116] In one specific embodiment, obtaining the front wheel steady-state yaw rate gain value based on operating data includes: obtaining the front wheel steady-state yaw rate gain value based on the vehicle longitudinal velocity in the operating data.

[0117] Specifically, the vehicle's longitudinal speed is input into a preset gain value calculation formula to obtain the front wheel steady-state yaw rate gain value output by the gain value calculation formula.

[0118] The formula for calculating the gain value is shown in formula (1):

[0119]

[0120] Among them, G f This represents the steady-state yaw rate gain of the front wheels, v. x Let L represent the vehicle's longitudinal velocity, L represent the sum of the distances from the front wheels to the center of gravity and the distances from the rear wheels to the center of gravity, and K represent the vehicle's stability coefficient, which is a constant.

[0121] Of course, the steady-state yaw rate gain of the front wheels can also be obtained by creating a mapping relationship between the vehicle's longitudinal speed and the front wheel steady-state yaw rate gain value. This can be achieved using a dictionary or a table.

[0122] Specifically, the process of determining formula (1) includes:

[0123] Based on the operational data, the motion differential equations of the linear two-degree-of-freedom front-wheel steering vehicle model are established, as shown in formulas (2) and (3):

[0124]

[0125] Where k1 represents the front wheel cornering stiffness, which is a constant; k2 represents the rear wheel cornering stiffness, which is a constant; β represents the center of mass offset angle; and ω... r δ represents the yaw rate. fLet represent the front wheel steering angle, m represent the vehicle's mass (a constant), a represent the distance from the front wheel to the center of gravity (a constant), b represent the distance from the rear wheel to the center of gravity (a constant), and I represent... z The moment of inertia is a constant. y Indicates lateral acceleration. It is ω r The derivative of .

[0126] Wherein, the transmission ratio is the ratio of the steering wheel angle to the front wheel angle, see formula (4).

[0127]

[0128] Where i represents the transmission ratio, δ sw Indicates the steering wheel angle, δ f Indicates the steering angle of the front wheels.

[0129] Specifically, the steady-state gain commonly used in vehicle evaluation indicators is adopted as the design basis, and the transmission ratio is designed using the steady-state gain of yaw rate, see formula (5):

[0130]

[0131] in, This represents the steady-state yaw rate gain of the steering wheel. This represents the steady-state yaw rate gain of the front wheels.

[0132] Among them, the steady-state yaw rate gain of the front wheel can be derived from a two-degree-of-freedom model under ideal conditions, i.e., formula (1).

[0133] Among them, in formula (1)

[0134] In one specific embodiment, the specific implementation of obtaining the transmission ratio surface diagram based on the transmission ratio variation range, minimum transmission ratio, assumed center ratio, and operating data includes:

[0135] The transmission ratio surface diagram is obtained based on the transmission ratio variation range, minimum transmission ratio, assumed center ratio, operating data, and preset surface diagram calculation formula.

[0136] Specifically, the transmission ratio surface diagram is obtained based on the transmission ratio variation range, minimum transmission ratio, assumed center ratio, steering wheel angle, and surface diagram calculation formula.

[0137] The formula for calculating the surface plot is shown in formula (6):

[0138]

[0139] Where i represents the transmission ratio, δ swH represents the steering wheel angle, and H represents the range of gear ratio variation. low σ represents the minimum transmission ratio, and σ represents the center ratio.

[0140] Specifically, in order to design a smooth transmission ratio surface and reduce the driver's operating burden, a normal function is introduced for optimization, resulting in formula (6). The gradient of the transmission ratio can be changed by adjusting one or more of the transmission ratio variation range, minimum transmission ratio, and center ratio in formula (6).

[0141] Of course, the transmission ratio can also be obtained by creating a mapping relationship between the transmission ratio variation range, minimum transmission ratio, assumed center ratio, operating data and transmission ratio. This mapping relationship can be implemented in dictionary or table form.

[0142] In one specific embodiment, the center ratio can be assumed to be 50.

[0143] In one specific embodiment, it can be assumed that the steady-state yaw rate gain of the steering wheel is 0.4, which is obtained by dividing the steering wheel angular rate by the steering wheel angle.

[0144] In one specific embodiment, based on the front wheel steady-state yaw rate gain value and the assumed steering wheel steady-state yaw rate gain value, the maximum transmission ratio and the minimum transmission ratio are obtained. Based on the maximum transmission ratio, the minimum transmission ratio, and the assumed center ratio, the specific implementation of the transmission ratio variation range includes:

[0145] The maximum transmission ratio is obtained based on the front wheel steady-state yaw rate gain, the assumed steering wheel steady-state yaw rate gain, and the preset maximum transmission ratio calculation formula.

[0146] The formula for calculating the maximum transmission ratio is given in formula (7):

[0147]

[0148] Among them, H high G represents the maximum transmission ratio. sw This represents the steady-state yaw rate gain of the steering wheel, v. x Let L represent the vehicle's longitudinal velocity, L represent the sum of the distances from the front wheels to the center of gravity and the distances from the rear wheels to the center of gravity, and K represent the vehicle's stability coefficient, which is a constant.

[0149] Specifically, the transmission ratio is greatest when the vehicle is traveling in a straight line, and based on this, formula (7) is obtained.

[0150] The minimum transmission ratio is obtained based on the formula for calculating the minimum transmission ratio.

[0151] The formula for calculating the minimum transmission ratio is given in formula (8):

[0152]

[0153] Among them, H low G represents the minimum transmission ratio. fL This represents the minimum value of the steady-state yaw rate gain of the front wheels.

[0154] Specifically, formula (8) is derived based on the vehicle's extreme turning angle.

[0155] Based on the maximum transmission ratio, minimum transmission ratio, assumed center ratio, and preset transmission ratio variation range calculation formula, the transmission ratio variation range is obtained.

[0156] The formula for calculating the range of transmission ratio variation is given in formula (9):

[0157]

[0158] Where H represents the range of transmission ratio variation, σ represents the center ratio, and normpdf represents the normal probability density function.

[0159] Furthermore, under normal circumstances, to ensure vehicle safety during cornering and prevent rollover accidents, certain limits are placed on the vehicle's lateral acceleration. To ensure vehicle safety during cornering as much as possible, let a... y =0.67.

[0160] Based on the lateral acceleration of the vehicle under extreme conditions, the vehicle's limit turning angle is obtained as follows, as shown in formula (10):

[0161]

[0162] By using the limit angle, the steady-state yaw rate gain of the front wheel can be obtained, and thus the range of transmission ratio variation can be obtained.

[0163] In one specific embodiment, based on the Cuckoo algorithm and vehicle stability evaluation index, the steady-state yaw rate gain and center ratio of the steering wheel corresponding to each speed segment are optimized to obtain the target steady-state yaw rate gain and target center ratio of the steering wheel corresponding to each speed segment. The specific implementation includes:

[0164] The following determination process is performed for the steady-state yaw rate gain and center ratio of the steering wheel corresponding to each speed segment:

[0165] Based on the Cuckoo algorithm, the steady-state yaw rate gain and center ratio of the steering wheel are set as the bird's nest; new steady-state yaw rate gain and new center ratio of the steering wheel are obtained based on Levy flight; the steady-state yaw rate gain and new steady-state yaw rate gain, as well as the center ratio and new center ratio of the steering wheel are compared; the health of the steady-state yaw rate gain and center ratio of the steering wheel are determined based on the vehicle stability evaluation index value corresponding to the speed segment; and when the number of iterations reaches the preset number, the steady-state yaw rate gain value of the steering wheel corresponding to the highest health is determined as the target steady-state yaw rate gain value of the steering wheel, and the center ratio corresponding to the highest health is determined as the target center ratio.

[0166] The speed ranges are determined based on vehicle speed. For example, they are divided into low-speed, medium-speed, medium-high-speed, and high-speed ranges. Speeds below 20 km / h are defined as low-speed, speeds between 20 km / h and 60 km / h as medium-speed, speeds between 60 km / h and 100 km / h as medium-high-speed, and speeds above 100 km / h as high-speed.

[0167] pass Figure 2 The determination process will be explained in detail:

[0168] Step 201: Initialize the steady-state yaw rate gain and center ratio of the steering wheel.

[0169] The initial value can be a hypothetical value.

[0170] Step 202: Based on Levi's flight, obtain the new steady-state yaw rate gain value of the steering wheel and the new center ratio.

[0171] Step 203: Compare the steady-state yaw rate gain and center ratio of the steering wheel with the previous generation, and select the one with higher health to retain.

[0172] Step 204: Determine if the number of iterations has been reached. If yes, proceed to step 205; otherwise, return to step 202.

[0173] Step 205: Determine the target steering wheel steady-state yaw rate gain value corresponding to the highest health level, and determine the target center ratio corresponding to the highest health level.

[0174] Considering the importance of driving safety during operation, vehicle stability evaluation indexes are calculated using trajectory tracking, handling load, rollover, and sideslip indicators. These vehicle stability evaluation indexes reflect the vehicle's safety performance during steering and can effectively determine its stability.

[0175] In one specific embodiment, vehicle stability evaluation index values ​​are obtained based on operational data, including:

[0176] The vehicle stability evaluation index value is obtained based on the vehicle stability evaluation formula.

[0177] The vehicle stability evaluation formula is shown in formula (11):

[0178]

[0179] Where J represents the vehicle stability evaluation index value, J E w represents the trajectory tracking metric value. E J represents the weighted value of the trajectory tracking index, which is a constant. B This indicates the value of the manipulation burden indicator, w B J represents the weighted value of the manipulation burden index, which is a constant. R This represents the rollover index value, w R J represents the weighted value of the rollover metric. S This represents the sideslip index value, w S This represents the weighted value of the sideslip index, which is a constant.

[0180] Among them, the trajectory tracking index value is calculated based on the total driving time of the vehicle, the actual driving path, the longitudinal speed of the vehicle, and the angular velocity of the vehicle's center of gravity offset; the handling load index value is calculated based on the steering wheel acceleration and steering wheel torque; the rollover index value is calculated based on the lateral acceleration and roll angle; and the sideslip index value is calculated based on the lateral force on the front axle, the front axle load, the lateral force on the rear axle, and the rear axle load.

[0181] Of course, vehicle stability evaluation index values ​​can also be obtained by creating a mapping relationship between vehicle stability evaluation index values ​​and trajectory tracking index values, handling burden index values, rollover index values ​​and sideslip index values. This mapping relationship can be implemented in dictionary or tabular form.

[0182] In one specific embodiment, the trajectory tracking index value is calculated based on the total vehicle travel time, the actual travel path, the vehicle's longitudinal velocity, and the vehicle's center of gravity offset angular velocity, including:

[0183] Input the total driving time and actual driving route into the preset path error calculation formula to obtain the path error output by the path error calculation formula.

[0184] The formula for calculating the path error is shown in formula (12):

[0185]

[0186] Among them, J e1 t represents the path error. nLet represent the total travel time, f(t) represent the desired path, and y(t) represent the actual travel path. This represents the standard value of the trajectory error, which is a constant.

[0187] Of course, the path error can also be obtained by creating a mapping relationship between the path error and the actual driving path. This mapping relationship can be implemented in the form of a dictionary or a table.

[0188] Input the vehicle bus speed and the vehicle center of gravity offset angular velocity into the preset direction error calculation formula to obtain the direction error output by the direction error calculation formula.

[0189] The formula for calculating the direction error is shown in formula (13):

[0190]

[0191] Among them, J e2 Indicates directional error, v x (t) represents the longitudinal velocity of the vehicle at time t. This represents the angular velocity of the vehicle's center of gravity at time t. This represents the standard value of the vehicle's center of gravity offset angular acceleration, which is a constant.

[0192] Of course, the direction error can also be obtained by creating a mapping relationship between the direction error and the vehicle's longitudinal velocity and the vehicle's center of gravity offset angular velocity. This mapping relationship can be implemented in dictionary or table form.

[0193] Input the path error and direction error into the preset trajectory tracking calculation formula to obtain the trajectory tracking index value output by the trajectory tracking calculation formula.

[0194] The trajectory tracking calculation formula is shown in formula (14):

[0195]

[0196] Among them, J E w represents the trajectory tracking metric value. e1 The weighted value representing the path error is a constant, w. e2 The weighted value representing the direction error is a constant.

[0197] Of course, the trajectory tracking index value can also be obtained by creating a mapping relationship between the trajectory tracking index value and the path error and direction error. Specifically, it can be implemented in dictionary form or table form.

[0198] In one specific embodiment, the handling load index value is calculated based on steering wheel acceleration and steering wheel torque, including:

[0199] Input the steering wheel acceleration into the preset busyness calculation formula to obtain the busyness level output by the busyness calculation formula.

[0200] The formula for calculating the level of busyness is shown in formula (15):

[0201]

[0202] Among them, J b1 t indicates the level of busyness n This indicates the total travel time of the vehicle. This represents the acceleration of the steering wheel at time t. This represents the standard value of steering wheel acceleration, which is a constant.

[0203] Of course, you can also create a mapping relationship between busyness and steering wheel acceleration, and obtain the busyness based on the created mapping relationship. Specifically, this can be implemented in the form of a dictionary or a table.

[0204] Input the steering wheel torque into the preset weight calculation formula to obtain the weight output by the weight calculation formula.

[0205] The formula for calculating the degree of heaviness is shown in formula (16):

[0206]

[0207] Among them, J b2 Indicating degree of weight, T sw (t) represents the steering wheel torque at time t. This represents the standard value of steering wheel torque, which is a constant.

[0208] Of course, the weight can also be determined by creating a mapping relationship between the weight and the steering wheel torque. This mapping relationship can be implemented using a dictionary or a table.

[0209] Input the busyness and heaviness into the preset operation burden calculation formula to obtain the operation burden index value output by the operation burden calculation formula.

[0210] The formula for calculating the manipulation burden is shown in formula (17):

[0211]

[0212] Among them, J B This indicates the value of the manipulation burden indicator, w b1 The weighted value representing the level of busyness is a constant, w. b2 The weighted value representing the degree of heaviness is a constant.

[0213] Of course, the manipulation burden index value can also be obtained by creating a mapping relationship between the manipulation burden index value and the busyness and heaviness. This mapping relationship can be implemented in the form of a dictionary or a table.

[0214] In one specific embodiment, the rollover index value is calculated based on lateral acceleration and roll angle, including:

[0215] Input the lateral acceleration into the preset lateral acceleration calculation formula to obtain the lateral acceleration output by the lateral acceleration calculation formula.

[0216] The formula for calculating lateral acceleration is shown in formula (18):

[0217]

[0218] Among them, J r1 Indicates lateral acceleration, t n Indicates the total travel time of the vehicle, a y (t) represents the lateral acceleration at time t. This represents the standard value of lateral acceleration, which is a constant.

[0219] Of course, the lateral acceleration can also be obtained by creating a mapping relationship between lateral acceleration and lateral acceleration. This mapping relationship can be implemented in the form of a dictionary or a table.

[0220] Input the roll angle into the preset roll condition calculation formula to obtain the roll condition output by the roll condition calculation formula.

[0221] The formula for calculating the roll is shown in formula (19):

[0222]

[0223] Among them, J r2 This indicates the roll condition, where φ(t) represents the roll angle at time t. This represents the standard value of the roll angle, which is a constant.

[0224] Of course, the roll condition can also be obtained by creating a mapping relationship between roll condition and roll angle. This mapping relationship can be implemented in dictionary or table form.

[0225] Input the lateral acceleration and rollover conditions into the preset rollover risk calculation formula to obtain the rollover index value output by the rollover risk calculation formula.

[0226] The formula for calculating the risk of rollover is shown in formula (20):

[0227]

[0228] Among them, J R J represents the rollover index value. r2 The weighted value representing lateral acceleration is a constant, w. r2 The weighted value representing the roll condition is a constant.

[0229] Of course, rollover index values ​​can also be obtained by creating a mapping relationship between rollover index values ​​and lateral acceleration and roll conditions. This mapping relationship can be implemented in dictionary or table form.

[0230] In one specific embodiment, the sideslip index value is calculated based on the lateral force on the front axle, the front axle load, the lateral force on the rear axle, and the rear axle load, including:

[0231] Input the lateral force and load on the front axle into the preset front axle sideslip risk calculation formula to obtain the front axle sideslip risk value output by the front axle sideslip risk calculation formula.

[0232] The formula for calculating the risk of front axle sideslip is shown in formula (21):

[0233]

[0234] Where J1 represents the front axle sideslip risk value, t n F represents the total driving time of the vehicle. y1 (t) represents the lateral force F acting on the front axle at time t. z1 (t) represents the front axle load at time t. This represents the lateral adhesion coefficient, which is a constant.

[0235] Of course, the front axle sideslip risk value can also be obtained by creating a mapping relationship between the front axle sideslip risk value and the lateral force and load on the front axle. This mapping relationship can be implemented in dictionary or tabular form.

[0236] Input the lateral force and load on the rear axle into the preset rear axle sideslip risk calculation formula to obtain the rear axle sideslip risk value output by the rear axle sideslip risk calculation formula.

[0237] The formula for calculating the risk of rear axle sideslip is shown in formula (22):

[0238]

[0239] Where J2 represents the rear axle sideslip risk value, F y2 (t) represents the lateral force F acting on the rear axle at time t. z2 (t) represents the rear axle load at time t. This represents the lateral adhesion coefficient, which is a constant.

[0240] Of course, the rear axle sideslip risk value can also be obtained by creating a mapping relationship between the rear axle sideslip risk value and the lateral force and load on the rear axle. This mapping relationship can be implemented in dictionary or tabular form.

[0241] Input the front axle sideslip hazard value and the rear axle sideslip hazard value into the preset sideslip hazard calculation formula to obtain the sideslip index value output by the sideslip hazard calculation formula.

[0242] The formula for calculating the risk of sideslip is shown in formula (23):

[0243] J S =max(J1,J2)................................(23)

[0244] Among them, J S This indicates the sideslip index value.

[0245] Of course, the sideslip index value can also be obtained by creating a mapping relationship between the sideslip index value and the front axle sideslip danger value and the rear axle sideslip danger value. The sideslip index value can be obtained based on the created mapping relationship, which can be implemented in dictionary form or table form.

[0246] This application compares the steady-state gain value and center ratio of different steering wheel angles by vehicle stability evaluation index values, and finally outputs the Bird's Nest with the highest health score after meeting the iteration conditions.

[0247] Figure 3 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 3 As shown, the electronic device may include a processor 301, a communication interface 302, a memory 303, and a communication bus 304. The processor 301, communication interface 302, and memory 303 communicate with each other via the communication bus 304. The processor 301 can call logical instructions from the memory 303 to execute a method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm.

[0248] Furthermore, the logical instructions in the aforementioned memory 303 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0249] On the other hand, the present invention also provides a computer program product, the computer program product including a computer program stored on a non-transitory computer-readable storage medium, the computer program including program instructions, and when the program instructions are executed by a computer, the computer is able to execute the transmission ratio determination method of the steer-by-wire system based on the cuckoo algorithm provided by the above methods.

[0250] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the method for determining the transmission ratio of the steer-by-wire system based on the cuckoo algorithm provided in the above embodiments.

[0251] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0252] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0253] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm, characterized in that, The method includes: Obtain vehicle operating data; Based on the aforementioned operational data, the front wheel steady-state yaw rate gain value and vehicle stability evaluation index value are obtained. Based on the front wheel steady-state yaw rate gain value and the assumed steering wheel steady-state yaw rate gain value, the maximum transmission ratio and the minimum transmission ratio are obtained, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, the transmission ratio variation range is obtained. Based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, and the operating data, a transmission ratio surface diagram is obtained; Based on the Cuckoo algorithm and the vehicle stability evaluation index, the steady-state yaw rate gain value of the steering wheel and the center ratio corresponding to each speed segment are optimized to obtain the target steady-state yaw rate gain value of the steering wheel and the target center ratio corresponding to each speed segment. The speed segment is divided based on the vehicle speed. Specifically, the following process is performed to determine the steady-state yaw rate gain and center ratio of the steering wheel for each speed segment: Based on the Cuckoo algorithm, the steady-state yaw rate gain and center ratio of the steering wheel are set as the bird's nest; based on the Levy flight, a new steady-state yaw rate gain and a new center ratio of the steering wheel are obtained; the steady-state yaw rate gain and the new steady-state yaw rate gain, as well as the center ratio and the new center ratio, are compared; the health of the steady-state yaw rate gain and the center ratio of the steering wheel are determined based on the vehicle stability evaluation index value corresponding to the speed segment; and when the number of iterations reaches the preset number, the steady-state yaw rate gain value of the steering wheel corresponding to the highest health is determined as the target steady-state yaw rate gain value of the steering wheel, and the center ratio corresponding to the highest health is determined as the target center ratio. The target steering wheel steady-state yaw rate gain value and the target center ratio are smoothed to obtain a target transmission ratio surface diagram, wherein the target transmission ratio surface diagram is used to characterize the correspondence between the operating data and the transmission ratio.

2. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to claim 1, characterized in that, Based on the front wheel steady-state yaw rate gain value and the assumed steering wheel steady-state yaw rate gain value, the maximum and minimum transmission ratios are obtained. Based on the maximum and minimum transmission ratios and the assumed center ratio, the transmission ratio variation range is obtained, including: Based on the front wheel steady-state yaw rate gain value, the assumed steering wheel steady-state yaw rate gain value, and the preset maximum transmission ratio calculation formula, the maximum transmission ratio is obtained; The formula for calculating the maximum transmission ratio includes: ； in, Indicates the maximum transmission ratio. This represents the steady-state yaw rate gain of the steering wheel. Indicates the longitudinal speed of the vehicle. It represents the sum of the distances from the front wheels to the center of gravity of the vehicle and the distances from the rear wheels to the center of gravity. The vehicle stability coefficient is a constant. The minimum transmission ratio is obtained based on the minimum transmission ratio calculation formula; The formula for calculating the minimum transmission ratio includes: ； in, Indicates the minimum transmission ratio. This represents the minimum value of the front wheel steady-state yaw rate gain. Based on the maximum transmission ratio, the minimum transmission ratio, the assumed center ratio, and the preset transmission ratio variation range calculation formula, the transmission ratio variation range is obtained; The formula for calculating the range of transmission ratio variation includes: ； in, Indicates the range of transmission ratio variation. Indicates the central ratio, This represents the probability density function of the normal distribution.

3. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to claim 2, characterized in that, Based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, and the operating data, a transmission ratio surface diagram is obtained, including: The transmission ratio surface diagram is obtained based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, the operating data, and the preset surface diagram calculation formula. The surface plot calculation formula includes: ； in, Indicates the transmission ratio. Indicates the steering wheel angle.

4. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to any one of claims 1-3, characterized in that, Based on the aforementioned operational data, vehicle stability evaluation index values ​​are obtained, including: The vehicle stability evaluation index value is obtained based on the vehicle stability evaluation formula; The vehicle stability evaluation formula includes: ； in, This indicates the vehicle stability evaluation index value. This represents the trajectory tracking index value. This represents the weighted value of the trajectory tracking metric, which is a constant. This indicates the manipulation of the burden indicator value. This represents the weighted value of the manipulation burden indicator, which is a constant. Indicates the rollover index value. This represents the weighted value of the rollover metric. This indicates the sideslip index value. This represents the weighted value of the sideslip index, which is a constant. The trajectory tracking index value is calculated based on the total vehicle driving time, actual driving path, vehicle longitudinal speed, and vehicle center of gravity offset angular velocity; the handling load index value is calculated based on steering wheel acceleration and steering wheel torque; the rollover index value is calculated based on lateral acceleration and roll angle; and the sideslip index value is calculated based on the lateral force on the front axle, front axle load, lateral force on the rear axle, and rear axle load.

5. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to claim 4, characterized in that, The trajectory tracking index is calculated based on the total vehicle travel time, actual travel path, vehicle longitudinal velocity, and vehicle center of gravity offset angular velocity, including: The total driving time of the vehicle and the actual driving route are input into a preset path error calculation formula to obtain the path error output by the path error calculation formula. The path error calculation formula includes: ； in, Indicates path error. This indicates the total travel time of the vehicle. Indicates the desired path, Indicates the actual driving route. This represents the standard value of the trajectory error, which is a constant. The vehicle bus speed and the vehicle center of gravity offset angular velocity are input into a preset direction error calculation formula to obtain the direction error output by the direction error calculation formula. The formula for calculating the direction error includes: ； in, Indicates directional error. This represents the longitudinal velocity of the vehicle at time t. This represents the angular velocity of the vehicle's center of gravity at time t. This represents the standard value of the vehicle's center of gravity offset angular acceleration, which is a constant. The path error and the direction error are input into a preset trajectory tracking calculation formula to obtain the trajectory tracking index value output by the trajectory tracking calculation formula; The trajectory tracking calculation formula includes: ； in, This represents the trajectory tracking index value. The weighted value representing the path error is a constant. The weighted value representing the direction error is a constant.

6. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to claim 4, characterized in that, The handling load index value is calculated based on steering wheel acceleration and steering wheel torque, including: The steering wheel acceleration is input into a preset busyness calculation formula to obtain the busyness level output by the busyness calculation formula; The formula for calculating the busyness level includes: ； in, Indicates the level of busyness. This indicates the total travel time of the vehicle. This represents the acceleration of the steering wheel at time t. This represents the standard value of steering wheel acceleration, which is a constant. The steering wheel torque is input into a preset weight calculation formula to obtain the weight output by the weight calculation formula; The formula for calculating the weight includes: ； in, Indicates the degree of heaviness. This represents the steering wheel torque at time t. This represents the standard value of steering wheel torque, which is a constant. Input the busyness level and the heaviness level into a preset operation burden calculation formula to obtain the operation burden index value output by the operation burden calculation formula; The formula for calculating the manipulation burden includes: ； in, This indicates the manipulation of the burden indicator value. The weighted value representing the level of busyness is a constant. The weighted value representing the degree of heaviness is a constant.

7. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to claim 4, characterized in that, The rollover index values ​​are calculated based on lateral acceleration and roll angle, including: The lateral acceleration is input into a preset lateral acceleration calculation formula to obtain the lateral acceleration output by the lateral acceleration calculation formula. The formula for calculating the lateral acceleration includes: ； in, Indicates lateral acceleration. This indicates the total travel time of the vehicle. This represents the lateral acceleration at time t. This represents the standard value of lateral acceleration, which is a constant. Input the roll angle into the preset roll condition calculation formula to obtain the roll condition output by the roll condition calculation formula; The formula for calculating the roll condition includes: ； in, Indicates the roll condition. This represents the roll angle at time t. This represents the standard value of the roll angle, which is a constant. The lateral acceleration and lateral tilt conditions are input into a preset rollover risk calculation formula to obtain the rollover index value output by the rollover risk calculation formula. The formula for calculating rollover risk includes: ； in, Indicates the rollover index value. The weighted value representing lateral acceleration is a constant. The weighted value representing the roll condition is a constant.

8. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to claim 4, characterized in that, The sideslip index value is calculated based on the lateral force on the front axle, the front axle load, the lateral force on the rear axle, and the rear axle load, including: Input the lateral force and load on the front axle into a preset front axle sideslip risk calculation formula to obtain the front axle sideslip risk value output by the front axle sideslip risk calculation formula; The formula for calculating the risk of front axle sideslip includes: ； in, Indicates the front axle sideslip risk level. This indicates the total travel time of the vehicle. This represents the lateral force acting on the front axle at time t. This represents the front axle load at time t. This represents the lateral adhesion coefficient, which is a constant. Input the lateral force and load on the rear axle into a preset rear axle sideslip risk calculation formula to obtain the rear axle sideslip risk value output by the rear axle sideslip risk calculation formula; The formula for calculating the risk of rear axle sideslip includes: ； in, Indicates the rear axle sideslip risk value. This represents the lateral force acting on the rear axle at time t. This represents the rear axle load at time t. This represents the lateral adhesion coefficient, which is a constant. Input the front axle sideslip hazard value and the rear axle sideslip hazard value into a preset sideslip hazard calculation formula to obtain the sideslip index value output by the sideslip hazard calculation formula; The formula for calculating the risk of sideslip includes: ； in, This indicates the sideslip index value.

9. The method for determining the transmission ratio of a steer-by-wire system based on the cuckoo algorithm according to any one of claims 1-3, characterized in that, Based on the aforementioned operational data, the steady-state yaw rate gain of the front wheels is obtained, including: Input the vehicle's longitudinal velocity into the gain value calculation formula to obtain the front wheel steady-state yaw rate gain value output by the gain value calculation formula; The formula for calculating the gain value includes: ； in, This represents the steady-state yaw rate gain of the front wheels. Indicates the longitudinal speed of the vehicle. It represents the sum of the distances from the front wheels to the center of gravity of the vehicle and the distances from the rear wheels to the center of gravity. This represents the vehicle stability coefficient, which is a constant.

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