Method for determining transmission ratio of steer-by-wire system based on cuckoo algorithm

Abstract

The invention discloses a method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm, and relates to the technical field of electric vehicle steering control. Obtaining a front wheel steady-state yaw velocity gain value and a vehicle stability evaluation index value; obtaining a maximum transmission ratio, a minimum transmission ratio and a transmission ratio change range; obtaining a transmission ratio curved surface diagram; based on a cuckoo algorithm and the vehicle stability evaluation index value, obtaining a target steering wheel steady-state yaw velocity gain value and a target center ratio corresponding to each speed section; and performing smoothing processing to obtain a target transmission ratio curved surface diagram. The method and the device are used for solving the problems of poor smoothness and poor accuracy when the transmission ratio of the steer-by-wire system is determined in the prior art, the smoothness and the accuracy of the determined transmission ratio are improved, and then the driving stability and the driving comfort of the vehicle are improved.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicle steering control, and in particular to a method for determining a transmission ratio of a wire-controlled steering system based on a cuckoo algorithm. Background Art

[0002] In recent years, the rapid development of the electric vehicle industry has brought about an increased demand for advanced driver assistance system technologies, among which vehicle stability is particularly critical. In traditional vehicles, the steering system relies on a fixed mechanical transmission ratio, but this limits the vehicle's ability to adjust performance at different speeds, making it difficult to simultaneously meet the requirements of sensitivity at low speeds and stability at high speeds. In contrast, the wire-controlled steering system used in electric vehicles abandons the physical connection between the steering wheel and the steering wheel and uses an electronic control system.

[0003] Among them, the steer-by-wire system is an advanced automotive steering technology that controls the steering of the car through electronic signals instead of traditional mechanical or hydraulic connections. The steer-by-wire system can design its own transmission ratio, which can improve the stability and driving comfort of the vehicle under various driving conditions. Therefore, the optimization and adjustment of the transmission ratio occupies an important position in the design of the steer-by-wire system and has become a key direction in the research of electric vehicle steering technology.

[0004] In the prior art, the design of the variable angle transmission ratio of the wire-controlled steering system adopts fuzzy control or an ideal transmission ratio that is not affected by the steering wheel angle. However, the transmission ratio of this design method has poor smoothness and accuracy, which leads to poor vehicle driving stability and poor driving comfort experience. Summary of the invention

[0005] In response to the above-mentioned problems and technical needs, the applicant has proposed a method for determining the transmission ratio of a wire-controlled steering system based on a cuckoo algorithm, so as to solve the problems of poor smoothness and poor accuracy in determining the transmission ratio of a wire-controlled steering system in the prior art, thereby improving the smoothness and accuracy of determining the transmission ratio, and thereby improving the vehicle driving stability and driving comfort.

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

[0007] Obtain vehicle operation data;

[0008] Based on the operating data, a front wheel steady-state yaw rate gain value and a 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, a maximum transmission ratio and a minimum transmission ratio are obtained, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, a 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 value, the steering wheel steady-state yaw angular velocity gain value and the center ratio corresponding to each speed segment are optimized to obtain a target steering wheel steady-state yaw angular velocity gain value and a target center ratio corresponding to each speed segment, wherein the speed segment is obtained based on the speed of the vehicle;

[0012] The target steering wheel steady-state yaw angular velocity 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 corresponding relationship between the motion data and the transmission ratio.

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

[0014] Obtaining a maximum transmission ratio based on the front wheel steady-state yaw rate gain value, an assumed steering wheel steady-state yaw rate gain value and a preset maximum transmission ratio calculation formula;

[0015] Wherein, the maximum transmission ratio calculation formula includes:

[0016]

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

[0018] Obtaining the minimum transmission ratio based on a minimum transmission ratio calculation formula;

[0019] Wherein, the minimum transmission ratio calculation formula includes:

[0020]

[0021] Among them, H low Indicates the minimum transmission ratio, G fL 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 a preset transmission ratio variation range calculation formula, a transmission ratio variation range is obtained;

[0023] Wherein, the transmission ratio variation range calculation formula includes:

[0024]

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

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

[0027] Obtaining the transmission ratio surface graph based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, the operating data and a preset surface graph calculation formula;

[0028] The surface graph 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 a method for determining a transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to an embodiment of the present application, based on the cuckoo algorithm and the vehicle stability evaluation index value, the steering wheel steady-state yaw angular velocity gain value and the center ratio corresponding to each speed segment are optimized to obtain a target steering wheel steady-state yaw angular velocity gain value and a target center ratio corresponding to each speed segment, including:

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

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

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

[0035] Obtaining the vehicle stability evaluation index value based on a vehicle stability evaluation formula;

[0036] Wherein, the vehicle stability evaluation formula includes:

[0037]

[0038] Among them, J represents the vehicle stability evaluation index value, J E represents the trajectory tracking index value, w E Represents the weighted value of the trajectory tracking index, which is a constant, J B represents the manipulation burden index value, w B It represents the weighted value of the manipulation burden index, which is a constant. R Indicates the rollover index value, w R represents the weighted value of the rollover index, J S Indicates the sideslip index value, w S It represents the weighted value of the sideslip index, which is a constant;

[0039] Among them, the trajectory tracking index value is calculated based on the total vehicle driving time, the actual driving path, the vehicle longitudinal speed and the vehicle center of mass offset angular velocity; the handling burden index value is calculated based on the steering wheel acceleration and the steering wheel torque; the rollover index value is calculated based on the lateral acceleration and the roll angle; 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.

[0040] According to a method for determining a transmission ratio of a steer-by-wire system based on a cuckoo algorithm in one embodiment of the present application, a 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 center of mass deviation of the vehicle, including:

[0041] Inputting the total driving time of the vehicle and the actual driving path into a preset path error calculation formula to obtain a path error output by the path error calculation formula;

[0042] The path error calculation formula includes:

[0043]

[0044] Among them, J e1 represents the path error, t n represents the total driving time of the vehicle, f(t) represents the expected path, y(t) represents the actual driving path, Represents the standard value of trajectory error, which is a constant;

[0045] Inputting the vehicle bus speed and the vehicle center of mass deviation angular velocity into a preset direction error calculation formula to obtain the direction error output by the direction error calculation formula;

[0046] The direction error calculation formula includes:

[0047]

[0048] Among them, J e2 represents the direction error, v x (t) represents the longitudinal velocity of the vehicle at time t, represents the angular velocity of the vehicle's center of mass deviation at time t, It represents the standard value of the vehicle's center of mass deviation angular acceleration, which is a constant;

[0049] Inputting the path error and the direction error into a preset trajectory tracking calculation formula to obtain a trajectory tracking index value output by the trajectory tracking calculation formula;

[0050] Wherein, the trajectory tracking calculation formula includes:

[0051]

[0052] Among them, J E represents the trajectory tracking index value, w e1 Represents the weighted value of the path error, which is a constant, w e2 Represents the weighted value of the direction error, which is a constant.

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

[0054] Inputting the steering wheel acceleration into a preset busyness calculation formula to obtain the busyness output by the busyness calculation formula;

[0055] The busyness calculation formula includes:

[0056]

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

[0058] Inputting the steering wheel torque into a preset heaviness calculation formula to obtain the heaviness output by the heaviness calculation formula;

[0059] The calculation formula for the heaviness degree includes:

[0060]

[0061] Among them, J b2 Indicates the severity, T sw (t) represents the steering wheel torque at time t, Indicates the standard value of steering wheel torque, which is a constant;

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

[0063] The manipulation burden calculation formula includes:

[0064]

[0065] Among them, J B represents the manipulation burden index value, w b1 Indicates the weighted value of busyness, which is a constant, w b2 A weighted value indicating the severity, which is a constant.

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

[0067] Inputting the lateral acceleration into a preset lateral acceleration calculation formula to obtain a lateral acceleration output by the lateral acceleration calculation formula;

[0068] The lateral acceleration calculation formula includes:

[0069]

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

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

[0072] The roll calculation formula includes:

[0073]

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

[0075] Inputting the lateral acceleration condition and the rollover condition into a preset rollover risk calculation formula to obtain a rollover index value output by the rollover risk calculation formula;

[0076] The rollover risk calculation formula includes:

[0077]

[0078] Among them, J R Represents the rollover index value, J r2 Represents the weighted value of lateral acceleration, which is a constant, w r2 Indicates the weighted value of the roll condition, which is a constant.

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

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

[0081] Wherein, the front axle sideslip risk calculation formula includes:

[0082]

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

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

[0085] Wherein, the rear axle sideslip risk calculation formula includes:

[0086]

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

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

[0089] Wherein, the sideslip risk calculation formula includes:

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

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

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

[0093] The longitudinal velocity of the vehicle is input into the gain value calculation formula to obtain the front wheel steady-state yaw angular velocity gain value output by the gain value calculation formula;

[0094] The gain value calculation formula includes:

[0095]

[0096] Among them, G f Represents the front wheel steady-state yaw rate gain value, v x represents the longitudinal speed of the vehicle, L represents the sum of the distance from the front wheel of the vehicle to the center of gravity and the distance from the rear wheel of the vehicle to the center of gravity, and K represents the vehicle stability coefficient, which is a constant.

[0097] The transmission ratio determination method of the wire control steering system based on the cuckoo algorithm provided in the embodiment of the present application links the steering wheel angle with the transmission ratio, designs a normal function variable angle transmission ratio related to the vehicle speed and the steering wheel angle, and ensures that the vehicle is smoother when turning and has better obstacle avoidance ability. The steering wheel steady-state gain and center ratio are optimized through the cuckoo optimization algorithm to enhance the steering ability of the vehicle, ensure that the vehicle is smoother when turning and has better obstacle avoidance ability, thereby improving the handling performance of the vehicle in each speed range. In addition, the vehicle speed is segmented to reduce the operating burden of the driver. The present application achieves the smoothness of the transmission ratio surface, improves the smoothness and accuracy of determining the transmission ratio, further improves the stability of the vehicle, and reduces the driver's operating burden and driving comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0099] Figure 1 It is one of the flow charts of the method for determining the transmission ratio of the wire control steering system based on the cuckoo algorithm provided in the embodiment of the present application;

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

[0101] Figure 3 It is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0102] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0103] The embodiment of the present application provides a method for determining the transmission ratio of a wire-controlled steering system based on a cuckoo algorithm. The method can be applied to a smart terminal or a server. Some other descriptions in the embodiment of the present application are for illustrative purposes only and are not intended to limit the scope of protection of the present application. They will not be described one by one in the following. The specific implementation of the method is as follows Figure 1 As shown:

[0104] Step 101, obtaining vehicle operation data.

[0105] Among them, the operating data include: vehicle longitudinal speed, center of mass offset angle, roll angle, yaw angular velocity, front wheel angle, steering wheel angle, total vehicle driving time, actual driving path, vehicle center of mass 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, etc.

[0106] Specifically, cameras, millimeter-wave radars, sensors and other devices can be used to collect operation data.

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

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

[0109] Step 104 , obtaining a transmission ratio surface diagram based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio and the operating data.

[0110] Step 105 , based on the cuckoo algorithm and the vehicle stability evaluation index value, optimize the steering wheel steady-state yaw rate gain value and the center ratio corresponding to each speed segment, and obtain the target steering wheel steady-state yaw rate gain value and the target center ratio corresponding to each speed segment.

[0111] The speed segments are divided based on the speed of the vehicle.

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

[0113] The target transmission ratio surface diagram is used to characterize the corresponding relationship between motion data and transmission ratio, and is specifically used to characterize the corresponding relationship between steering wheel angle and transmission ratio.

[0114] Specifically, the target transmission ratio curve diagram between each speed segment is smoothly transitioned, so that the target transmission ratio curve diagram of the entire road segment can be obtained, and the target transmission ratio curve diagram changes with the vehicle speed and the turning angle of the pay-off drum.

[0115] The transmission ratio determination method of the wire control steering system based on the cuckoo algorithm provided in the embodiment of the present application links the steering wheel angle with the transmission ratio, designs a normal function variable angle transmission ratio related to the vehicle speed and the steering wheel angle, and ensures that the vehicle is smoother when turning and has better obstacle avoidance ability. The steering wheel steady-state gain and center ratio are optimized through the cuckoo optimization algorithm to enhance the steering ability of the vehicle, ensure that the vehicle is smoother when turning and has better obstacle avoidance ability, thereby improving the handling performance of the vehicle in each speed range. In addition, the vehicle speed is segmented to reduce the operating burden of the driver. The present application achieves the smoothness of the transmission ratio surface, improves the smoothness and accuracy of determining the transmission ratio, further improves the stability of the vehicle, and reduces the driver's operating burden and driving comfort.

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

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

[0118] The gain value calculation formula is shown in formula (1):

[0119]

[0120] Among them, G f Represents the front wheel steady-state yaw rate gain value, v x represents the longitudinal speed of the vehicle, L represents the sum of the distance from the front wheel of the vehicle to the center of gravity and the distance from the rear wheel of the vehicle to the center of gravity, and K represents the vehicle stability coefficient, which is a constant.

[0121] Of course, a mapping relationship between the vehicle longitudinal speed and the front wheel steady-state yaw rate gain value may also be created, and the front wheel steady-state yaw rate gain value may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

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

[0123] The motion differential equation of the vehicle linear two-degree-of-freedom front-wheel steering vehicle model is established based on the operating data, see formula (2) and formula (3):

[0124]

[0125] Among them, k1 represents the front wheel turning stiffness, which is a constant, k2 represents the rear wheel turning stiffness, which is a constant, β represents the center of mass deviation angle, ω r represents the yaw rate, δ frepresents the front wheel turning angle, m represents the mass of the vehicle, which is a constant, a represents the distance from the front wheel to the center of gravity, which is a constant, b represents the distance from the rear wheel to the center of gravity, which is a constant, I z represents the moment of inertia, which is a constant, a y represents the lateral acceleration, Yes r The derivative value of .

[0126] 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 represents the steering wheel angle, δ f Indicates the front wheel turning angle.

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

[0130]

[0131] in, Indicates the steering wheel steady-state yaw rate gain value, Indicates the front wheel steady-state yaw rate gain value.

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

[0133] Among them, in formula (1)

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

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

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

[0137] The surface plot calculation formula is shown in formula (6):

[0138]

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

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

[0141] Of course, it is also possible to create a mapping relationship between the transmission ratio variation range, minimum transmission ratio, assumed center ratio, operating data and transmission ratio, and obtain the transmission ratio based on the created mapping relationship, which can be implemented in a dictionary or table form.

[0142] In a specific embodiment, it can be assumed that the center ratio is 50.

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

[0144] In a 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, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, the specific implementation of obtaining the transmission ratio variation range includes:

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

[0146] The maximum transmission ratio calculation formula is shown in formula (7):

[0147]

[0148] Among them, H high Indicates the maximum transmission ratio, G sw Represents the steering wheel steady-state yaw rate gain value, v x represents the longitudinal speed of the vehicle, L represents the sum of the distance from the front wheel of the vehicle to the center of gravity and the distance from the rear wheel of the vehicle to the center of gravity, and K represents the vehicle stability coefficient, which is a constant.

[0149] Specifically, the transmission ratio of the vehicle is the largest when it is traveling in a straight line, based on which formula (7) is obtained.

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

[0151] The minimum transmission ratio calculation formula is shown in formula (8):

[0152]

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

[0154] Specifically, formula (8) is obtained based on the situation where the vehicle is at a limit turning angle.

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

[0156] The calculation formula for the transmission ratio variation range is shown in formula (9):

[0157]

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

[0159] Moreover, in general, in order to ensure the safety of the vehicle when turning and prevent rollover accidents, certain restrictions are placed on the lateral acceleration of the vehicle. y =0.67.

[0160] According to the lateral acceleration of the vehicle under extreme conditions, the vehicle's extreme turning angle is obtained as follows, see formula (10):

[0161]

[0162] The front wheel steady-state yaw rate gain value can be obtained through the limit turning angle, and then the transmission ratio variation range can be obtained.

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

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

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

[0166] The speed segment is divided based on the speed of the vehicle. For example, it is divided into a low speed segment, a medium speed segment, a medium-high speed segment and a high speed segment. A vehicle speed below 20 km / h is determined as a low speed segment, a vehicle speed between 20 km / h and 60 km / h is determined as a medium speed segment, a vehicle speed between 60 km / h and 100 km / h is determined as a medium-high speed segment, and a vehicle speed greater than 100 km / h is determined as a high speed segment.

[0167] pass Figure 2 The determination process is described in detail:

[0168] Step 201, initializing the steering wheel steady-state yaw rate gain value and center ratio.

[0169] The initialized value may be an assumed value.

[0170] Step 202, obtaining a new steering wheel steady-state yaw rate gain value and a new center ratio based on Levy flight.

[0171] Step 203 , comparing the steering wheel steady-state yaw rate gain value and center ratio with the previous generation, and selecting the one with higher healthiness to keep.

[0172] Step 204, determine whether the number of iterations has been reached, if so, execute step 205, otherwise, return to execute step 202.

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

[0174] Considering the importance of driving safety in the driving process, the vehicle stability evaluation index value is calculated through trajectory tracking index, handling burden index, rollover index and sideslip index. Among them, the vehicle stability evaluation index value reflects the safety performance of the vehicle when turning, which can effectively judge the stability of the vehicle.

[0175] In a specific embodiment, obtaining a vehicle stability evaluation index value based on the operating data includes:

[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] Among them, J represents the vehicle stability evaluation index value, J E represents the trajectory tracking index value, w E Represents the weighted value of the trajectory tracking index, which is a constant, J B represents the manipulation burden index value, w B It represents the weighted value of the manipulation burden index, which is a constant. R Indicates the rollover index value, w R represents the weighted value of the rollover index, J S Indicates the sideslip index value, w S 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 vehicle driving time, actual driving path, vehicle longitudinal speed and vehicle center of mass offset angular velocity; the handling burden 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; 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.

[0181] Of course, it is also possible to create a mapping relationship between the vehicle stability evaluation index value and the trajectory tracking index value, the handling burden index value, the rollover index value and the sideslip index value, and obtain the vehicle stability evaluation index value based on the created mapping relationship, which can be implemented in a dictionary form or a table form.

[0182] In a specific embodiment, 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 center of mass deviation of the vehicle, including:

[0183] The total driving time and the actual driving path of the vehicle are input into a preset path error calculation formula to obtain the path error output by the path error calculation formula.

[0184] The path error calculation formula is shown in formula (12):

[0185]

[0186] Among them, J e1 represents the path error, t nrepresents the total driving time of the vehicle, f(t) represents the expected path, y(t) represents the actual driving path, Represents the standard value of trajectory error, which is a constant.

[0187] Of course, a mapping relationship between the path error and the actual driving path may also be created, and the path error may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

[0188] The vehicle bus speed and the vehicle center of mass offset angular velocity are input into a preset direction error calculation formula to obtain the direction error output by the direction error calculation formula.

[0189] The direction error calculation formula is shown in formula (13):

[0190]

[0191] Among them, J e2 represents the direction error, v x (t) represents the longitudinal velocity of the vehicle at time t, represents the angular velocity of the vehicle's center of mass deviation at time t, It represents the standard value of the vehicle's center of mass deviation angular acceleration, which is a constant.

[0192] Of course, it is also possible to create a mapping relationship between the direction error and the longitudinal velocity of the vehicle and the angular velocity of the center of mass offset of the vehicle, and obtain the direction error based on the created mapping relationship, which can be implemented in a dictionary form or a table form.

[0193] The path error and the direction error are input into a preset trajectory tracking calculation formula to obtain a 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 represents the trajectory tracking index value, w e1 Represents the weighted value of the path error, which is a constant, w e2 Represents the weighted value of the direction error, which is a constant.

[0197] Of course, it is also possible to create a mapping relationship between the trajectory tracking index value and the path error and the direction error, and obtain the trajectory tracking index value based on the created mapping relationship, which can be specifically implemented in a dictionary form or a table form.

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

[0199] The steering wheel acceleration is input into a preset busyness calculation formula to obtain the busyness output by the busyness calculation formula.

[0200] The busyness calculation formula is shown in formula (15):

[0201]

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

[0203] Of course, a mapping relationship between the busyness and the steering wheel acceleration may be created, and the busyness may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

[0204] The steering wheel torque is input into a preset heaviness calculation formula to obtain the heaviness output by the heaviness calculation formula.

[0205] The calculation formula for the heaviness is shown in formula (16):

[0206]

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

[0208] Of course, a mapping relationship between the heaviness and the steering wheel torque may be created, and the heaviness may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

[0209] The busyness and heaviness are input into a preset operation burden calculation formula to obtain an operation burden index value output by the operation burden calculation formula.

[0210] The calculation formula of the manipulation burden is shown in formula (17):

[0211]

[0212] Among them, J B represents the manipulation burden index value, w b1 Indicates the weighted value of busyness, which is a constant, w b2 A weighted value indicating the severity, which is a constant.

[0213] Of course, a mapping relationship between the manipulation burden index value and the busyness and heaviness can also be created, and the manipulation burden index value can be obtained based on the created mapping relationship, which can be implemented in a dictionary form or a table form.

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

[0215] The lateral acceleration is input into a preset lateral acceleration calculation formula to obtain a lateral acceleration output by the lateral acceleration calculation formula.

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

[0217]

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

[0219] Of course, a mapping relationship between the lateral acceleration situation and the lateral acceleration may also be created, and the lateral acceleration situation may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

[0220] The roll angle is input into a preset roll condition calculation formula to obtain a roll condition output by the roll condition calculation formula.

[0221] The roll calculation formula is shown in formula (19):

[0222]

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

[0224] Of course, a mapping relationship between the roll situation and the roll angle may also be created, and the roll situation may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

[0225] The lateral acceleration and the rollover condition are input into a preset rollover risk calculation formula to obtain a rollover index value output by the rollover risk calculation formula.

[0226] The rollover risk calculation formula is shown in formula (20):

[0227]

[0228] Among them, J R Represents the rollover index value, J r2 Represents the weighted value of lateral acceleration, which is a constant, w r2 Indicates the weighted value of the roll condition, which is a constant.

[0229] Of course, a mapping relationship between the rollover index value and the lateral acceleration and the rollover condition may also be created, and the rollover index value may be obtained based on the created mapping relationship, which may be implemented in a dictionary form or a table form.

[0230] In a specific embodiment, the side slip 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] The lateral force and the front axle load on the front axle are input into a preset front axle sideslip risk calculation formula to obtain a front axle sideslip risk value output by the front axle sideslip risk calculation formula.

[0232] The front axle sideslip risk calculation formula is shown in formula (21):

[0233]

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

[0235] Of course, a mapping relationship between the front axle sideslip risk value and the lateral force and front axle load on the front axle can be created, and the front axle sideslip risk value can be obtained based on the created mapping relationship, which can be implemented in a dictionary form or a table form.

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

[0237] The rear axle side slip risk calculation formula is shown in formula (22):

[0238]

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

[0240] Of course, a mapping relationship between the rear axle sideslip risk value and the lateral force and rear axle load on the rear axle can be created, and the rear axle sideslip risk value can be obtained based on the created mapping relationship, which can be implemented in a dictionary form or a table form.

[0241] The front axle sideslip risk value and the rear axle sideslip risk value are input into a preset sideslip risk calculation formula to obtain a sideslip index value output by the sideslip risk calculation formula.

[0242] The calculation formula for the side slip risk is shown in formula (23):

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

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

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

[0246] This application compares the steady-state gain values ​​and center ratios of different steering wheel angles through the vehicle stability evaluation index value, and finally satisfies the iteration conditions and outputs the bird's nest with the highest health.

[0247] Figure 3 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 3 As shown, the electronic device may include: a processor 301, a communication interface 302, a memory 303 and a communication bus 304, wherein the processor 301, the communication interface 302 and the memory 303 communicate with each other through the communication bus 304. The processor 301 may call the logic instructions in the memory 303 to execute the transmission ratio determination method of the wire control steering system based on the cuckoo algorithm.

[0248] In addition, the logic instructions in the above-mentioned memory 303 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0249] On the other hand, the present invention also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the transmission ratio determination method of the wire-controlled steering system based on the cuckoo algorithm provided by the above-mentioned methods.

[0250] On the other hand, 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 execute the transmission ratio determination method of the wire-controlled steering system based on the cuckoo algorithm provided in the above-mentioned embodiments.

[0251] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0252] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0253] Finally, it should be noted that the above is only the preferred implementation of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.

Claims

1. A method for determining the transmission ratio of a wire-controlled steering system based on a cuckoo algorithm, characterized in that: The method comprises: Obtain vehicle operation data; Based on the operating data, a front wheel steady-state yaw rate gain value and a 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, a maximum transmission ratio and a minimum transmission ratio are obtained, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, a 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 value, the steering wheel steady-state yaw angular velocity gain value and the center ratio corresponding to each speed segment are optimized to obtain a target steering wheel steady-state yaw angular velocity gain value and a target center ratio corresponding to each speed segment, wherein the speed segment is obtained based on the speed of the vehicle; The target steering wheel steady-state yaw angular velocity 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 corresponding relationship between the motion data and the transmission ratio.

2. The method for determining the transmission ratio of a steer-by-wire system based on a 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, a maximum transmission ratio and a minimum transmission ratio are obtained, and based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio, a transmission ratio variation range is obtained, including: Obtaining a maximum transmission ratio based on the front wheel steady-state yaw rate gain value, an assumed steering wheel steady-state yaw rate gain value and a preset maximum transmission ratio calculation formula; Wherein, the maximum transmission ratio calculation formula includes: Among them, H high Indicates the maximum transmission ratio, G sw Represents the steering wheel steady-state yaw rate gain value, v x represents the longitudinal speed of the vehicle, L represents the sum of the distance from the front wheel of the vehicle to the center of gravity and the distance from the rear wheel of the vehicle to the center of gravity, and K represents the vehicle stability coefficient, which is a constant; Obtaining the minimum transmission ratio based on a minimum transmission ratio calculation formula; Wherein, the minimum transmission ratio calculation formula includes: Among them, H low Indicates the minimum transmission ratio, G fL 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 a preset transmission ratio variation range calculation formula, a transmission ratio variation range is obtained; Wherein, the transmission ratio variation range calculation formula includes: Among them, H represents the transmission ratio variation range, σ represents the center ratio, and normpdf represents the normal distribution probability density function.

3. The method for determining the transmission ratio of a steer-by-wire system based on a 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: Obtaining the transmission ratio surface graph based on the transmission ratio variation range, the minimum transmission ratio, the assumed center ratio, the operating data and a preset surface graph calculation formula; The surface graph calculation formula includes: i=H·normpdf(δ sw ,0,σ)+H low ; Where i represents the transmission ratio, δ sw Indicates the steering wheel angle.

4. The method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to any one of claims 1 to 3, characterized in that: Based on the cuckoo algorithm and the vehicle stability evaluation index value, the steering wheel steady-state yaw angular velocity gain value and the center ratio corresponding to each speed segment are optimized to obtain a target steering wheel steady-state yaw angular velocity gain value and a target center ratio corresponding to each speed segment, including: The following determination process is performed for the steering wheel steady-state yaw rate gain value and center ratio corresponding to each speed segment: The steering wheel steady-state yaw rate gain value and the center ratio are set as a bird's nest based on the cuckoo algorithm; a new steering wheel steady-state yaw rate gain value and a new center ratio are obtained based on the Levy flight; the steering wheel steady-state yaw rate gain value and the new steering wheel steady-state yaw rate gain value, as well as the center ratio and the new center ratio are compared; the health of the steering wheel steady-state yaw rate gain value and the center ratio is determined based on the vehicle stability evaluation index value corresponding to the speed segment, and when the number of iterations reaches a preset number, the steering wheel steady-state yaw rate gain value corresponding to the highest health is determined as the target steering wheel steady-state yaw rate gain value, and the center ratio corresponding to the highest health is determined as the target center ratio.

5. The method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to any one of claims 1 to 3, characterized in that: Based on the operating data, a vehicle stability evaluation index value is obtained, including: Obtaining the vehicle stability evaluation index value based on a vehicle stability evaluation formula; Wherein, the vehicle stability evaluation formula includes: Among them, J represents the vehicle stability evaluation index value, J E represents the trajectory tracking index value, w E Represents the weighted value of the trajectory tracking index, which is a constant, J B represents the manipulation burden index value, w B It represents the weighted value of the manipulation burden index, which is a constant. R Indicates the rollover index value, w R represents the weighted value of the rollover index, J S Indicates the sideslip index value, w S It represents the weighted value of the sideslip index, which is a constant; Among them, the trajectory tracking index value is calculated based on the total vehicle driving time, the actual driving path, the vehicle longitudinal speed and the vehicle center of mass offset angular velocity; the handling burden index value is calculated based on the steering wheel acceleration and the steering wheel torque; the rollover index value is calculated based on the lateral acceleration and the roll angle; 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.

6. The method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to claim 5, characterized in that: The trajectory tracking index value is calculated based on the total driving time of the vehicle, the actual driving path, the vehicle longitudinal speed and the vehicle center of mass offset angular velocity, including: Inputting the total driving time of the vehicle and the actual driving path into a preset path error calculation formula to obtain a path error output by the path error calculation formula; The path error calculation formula includes: Among them, J e1 represents the path error, tn represents the total driving time of the vehicle, f(t) represents the expected path, y(t) represents the actual driving path, Represents the standard value of trajectory error, which is a constant; Inputting the vehicle bus speed and the vehicle center of mass deviation angular velocity into a preset direction error calculation formula to obtain the direction error output by the direction error calculation formula; The direction error calculation formula includes: Among them, J e2 represents the direction error, v x (t) represents the longitudinal velocity of the vehicle at time t, represents the angular velocity of the vehicle's center of mass deviation at time t, It represents the standard value of the vehicle's center of mass deviation angular acceleration, which is a constant; Inputting the path error and the direction error into a preset trajectory tracking calculation formula to obtain a trajectory tracking index value output by the trajectory tracking calculation formula; Wherein, the trajectory tracking calculation formula includes: Among them, J E represents the trajectory tracking index value, w e1 Represents the weighted value of the path error, which is a constant, w e2 Represents the weighted value of the direction error, which is a constant.

7. The method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to claim 5, characterized in that: The steering load index value is calculated based on the steering wheel acceleration and steering wheel torque, including: Inputting the steering wheel acceleration into a preset busyness calculation formula to obtain the busyness output by the busyness calculation formula; The busyness calculation formula includes: Among them, J b1 Indicates the busyness, tn indicates the total driving time of the vehicle, represents the steering wheel acceleration at time t, Indicates the standard value of steering wheel acceleration, which is a constant; Inputting the steering wheel torque into a preset heaviness calculation formula to obtain the heaviness output by the heaviness calculation formula; The calculation formula for the heaviness degree includes: Among them, J b2 Indicates the severity, T sw (t) represents the steering wheel torque at time t, Indicates the standard value of steering wheel torque, which is a constant; Inputting the busyness and the heaviness into a preset operation burden calculation formula to obtain an operation burden index value output by the operation burden calculation formula; The operation burden calculation formula includes: Among them, J B represents the manipulation burden index value, w b1 Indicates the weighted value of busyness, which is a constant, w b2 A weighted value indicating the severity, which is a constant.

8. The method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to claim 5, characterized in that: The rollover index value is calculated based on the lateral acceleration and roll angle, including: Inputting the lateral acceleration into a preset lateral acceleration calculation formula to obtain a lateral acceleration output by the lateral acceleration calculation formula; The lateral acceleration calculation formula includes: Among them, J r1 represents the lateral acceleration, tn represents the total driving time of the vehicle, a y (t) represents the lateral acceleration at time t, It represents the standard value of lateral acceleration, which is a constant; Inputting the roll angle into a preset roll condition calculation formula to obtain a roll condition output by the roll condition calculation formula; The roll calculation formula includes: Among them, J r2 represents the roll condition, φ(t) represents the roll angle at time t, Indicates the standard value of the roll angle, which is a constant; Inputting the lateral acceleration condition and the rollover condition into a preset rollover risk calculation formula to obtain a rollover index value output by the rollover risk calculation formula; The rollover risk calculation formula includes: Among them, J R Represents the rollover index value, J r2 Represents the weighted value of lateral acceleration, which is a constant, w r2 Indicates the weighted value of the roll condition, which is a constant.

9. The method for determining the transmission ratio of a steer-by-wire system based on a cuckoo algorithm according to claim 5, characterized in that: The side slip 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: Inputting the lateral force on the front axle and the front axle load into a preset front axle sideslip risk calculation formula to obtain a front axle sideslip risk value output by the front axle sideslip risk calculation formula; Wherein, the front axle sideslip risk calculation formula includes: Among them, J1 represents the front axle sideslip risk value, tn represents the total driving time of the vehicle, and F y1 (t) represents the lateral force on the front axle at time t, F z1 (t) represents the front axle load at time t, represents the lateral adhesion coefficient, which is a constant; Inputting the lateral force on the rear axle and the rear axle load into a preset rear axle sideslip risk calculation formula to obtain a rear axle sideslip risk value output by the rear axle sideslip risk calculation formula; Wherein, the rear axle sideslip risk calculation formula includes: Among them, J2 represents the rear axle sideslip risk value, F y2 (t) represents the lateral force on the rear axle at time t, F z2 (t) represents the rear axle load at time t, represents the lateral adhesion coefficient, which is a constant; Inputting the front axle sideslip risk value and the rear axle sideslip risk value into a preset sideslip risk calculation formula to obtain a sideslip index value output by the sideslip risk calculation formula; Wherein, the sideslip risk calculation formula includes: J S =max ( J1,J2); Among them, J S Indicates the sideslip index value.

10. The steering control method of an electric vehicle based on a transmission ratio according to any one of claims 1 to 3, characterized in that: Based on the operating data, a front wheel steady-state yaw rate gain value is obtained, including: The longitudinal velocity of the vehicle is input into the gain value calculation formula to obtain the front wheel steady-state yaw angular velocity gain value output by the gain value calculation formula; The gain value calculation formula includes: Among them, G f Represents the front wheel steady-state yaw rate gain value, v x represents the longitudinal speed of the vehicle, L represents the sum of the distance from the front wheel of the vehicle to the center of gravity and the distance from the rear wheel of the vehicle to the center of gravity, and K represents the vehicle stability coefficient, which is a constant.

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