CN-119472289-B - Transmission ratio determining method of drive-by-wire steering system based on cuckoo algorithm

Abstract

The application discloses a transmission ratio determining method of a drive-by-wire steering system based on a cuckoo algorithm, which relates to the technical field of electric automobile steering control and comprises the steps of obtaining running data of a vehicle; obtaining a front wheel steady-state yaw rate gain value and a vehicle stability evaluation index value, obtaining a maximum transmission ratio, a minimum transmission ratio and a transmission ratio variation range, obtaining a transmission ratio curved surface graph, obtaining a target steering wheel steady-state yaw rate gain value and a target center ratio corresponding to each speed section based on a cuckoo algorithm and the vehicle stability evaluation index value, and performing smoothing treatment to obtain the target transmission ratio curved surface graph. The method and the device are used for solving the problems of poor smoothness and poor precision in the prior art when the transmission ratio of the steer-by-wire system is determined, and realizing the improvement of the smoothness and the precision of the transmission ratio determination, thereby improving the driving stability and the driving comfort of the vehicle.

Inventors

• SHEN YANXIA
• LIU LONGCHAO
• ZHAO ZHIPU

Assignees

• 江南大学

Dates

Publication Date

20260505

Application Date

20241112

Claims (9)

1. 1. A method for determining a gear ratio of a steering-by-wire system based on a cuckoo algorithm, the method comprising: Acquiring operation data of a vehicle; based on the operation data, obtaining a front wheel steady yaw rate gain value and a vehicle stability evaluation index value; 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 change range based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio; obtaining a gear ratio curved surface diagram based on the gear ratio change range, the minimum gear ratio, the assumed center ratio and the operation data; optimizing the steady-state yaw rate gain value and the center ratio of the steering wheel corresponding to each speed segment based on a cuckoo algorithm and the vehicle stability evaluation index value to obtain a target steady-state yaw rate gain value and a target center ratio of the steering wheel corresponding to each speed segment, wherein the speed segments are obtained based on the speed of the vehicle; wherein, for each speed segment, the following determination process is performed for the steady-state yaw rate gain value and the center ratio of the steering wheel: setting a steady-state yaw rate gain value and a center ratio of the steering wheel as bird nests based on a cuckoo algorithm, obtaining a new steady-state yaw rate gain value and a new center ratio of the steering wheel based on Lewy flight, comparing the steady-state yaw rate gain value and the new steady-state yaw rate gain value of the steering wheel with the center ratio and the new center ratio, determining the health degree of the steady-state yaw rate gain value and the center ratio of the steering wheel based on vehicle stability evaluation index values corresponding to speed segments, and determining the steady-state yaw rate gain value of the steering wheel corresponding to the highest health degree as a target steady-state yaw rate gain value and the corresponding center ratio of the steering wheel when the highest health degree is determined as a target center ratio under the condition that the iteration times reaches preset times; And smoothing the steady-state yaw rate gain value of the target steering wheel and the target center ratio to obtain a target transmission ratio curved surface diagram, wherein the target transmission ratio curved surface diagram is used for representing the corresponding relation between the running data and the transmission ratio.
2. 2. The gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to claim 1, wherein obtaining a maximum gear ratio and a minimum gear 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 gear ratio variation range based on the maximum gear ratio, the minimum gear ratio, and the assumed center ratio, comprises: obtaining a maximum transmission ratio 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; the maximum transmission ratio calculation formula comprises: ; Wherein, the The maximum transmission ratio is indicated to be the maximum transmission ratio, Indicating a steering wheel steady state yaw rate gain value, Indicating the longitudinal speed of the vehicle, Represents the sum of the distance from the front wheel to the center of gravity of the vehicle and the distance from the rear wheel to the center of gravity of the vehicle, Representing the stability coefficient of the vehicle as a constant; Obtaining the minimum transmission ratio based on a minimum transmission ratio calculation formula; Wherein the minimum gear ratio calculation formula includes: ; Wherein, the The minimum gear ratio is indicated and the minimum gear ratio is indicated, A minimum value representing the front wheel steady-state yaw rate gain value; Obtaining a transmission ratio change range based on the maximum transmission ratio, the minimum transmission ratio, the assumed center ratio and a preset transmission ratio change range calculation formula; wherein, the transmission ratio variation range calculation formula includes: ; Wherein, the A range of gear ratio changes is indicated, The center ratio is represented by the ratio of centers, Representing a normal distribution probability density function.
3. 3. The gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to claim 2, wherein obtaining a gear ratio curved surface map based on the gear ratio variation range, the minimum gear ratio, an assumed center ratio, and the operation data comprises: Obtaining a gear ratio curved surface diagram based on the gear ratio change range, the minimum gear ratio, the assumed center ratio, the operation data and a preset curved surface diagram calculation formula; wherein, the curved surface graph calculation formula includes: ; Wherein, the The transmission ratio is indicated as such, Indicating the steering wheel angle.
4. 4. A transmission ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to any one of claims 1 to 3, wherein obtaining a vehicle stability evaluation index value based on the operation data comprises: Obtaining the vehicle stability evaluation index value based on a vehicle stability evaluation formula; wherein the vehicle stability evaluation formula includes: ; Wherein, the The vehicle stability evaluation index value is represented, The trajectory tracking index value is represented, The weight value representing the track trace index is a constant, Represents the manipulation burden index value, The weight value representing the manipulation burden index is a constant, Indicating the rollover index value, The weighted value representing the rollover index, Represents the sideslip index value, A weighted value representing the sideslip index is a constant; The track tracking index value is calculated based on the total running time of the vehicle, the actual running path, the longitudinal speed of the vehicle and the centroid deviation angular speed of the vehicle, the steering burden index value is calculated based on the steering wheel acceleration and the steering wheel moment, the rollover index value is calculated based on the lateral acceleration and the roll angle, and the sideslip index value is calculated based on the lateral force born by the front axle, the front axle load, the lateral force born by the rear axle and the rear axle load.
5. 5. The gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to claim 4, wherein the trajectory tracking index value is calculated based on a total vehicle travel time period, an actual travel path, a vehicle longitudinal speed, and a vehicle centroid offset angular speed, comprising: inputting the total running time of the vehicle and the actual running path into a preset path error calculation formula to obtain a path error output by the path error calculation formula; wherein the path error calculation formula includes: ; Wherein, the The path error is indicated as such, The total length of time the vehicle is traveling is indicated, The desired path is indicated and, The actual travel path is indicated and the actual travel path is indicated, The standard value of the track error is represented as a constant; Inputting the bus speed of the vehicle and the centroid offset angular speed of the vehicle into a preset direction error calculation formula to obtain a direction error output by the direction error calculation formula; Wherein, the direction error calculation formula includes: ; Wherein, the Indicating the error in the direction of the light, The vehicle longitudinal speed at time t is indicated, Represents the vehicle centroid offset angular velocity at time t, The standard value of the acceleration of the vehicle mass center deviation angle is represented as a constant; Inputting the path error and the direction error into a preset track tracking calculation formula to obtain a track tracking index value output by the track tracking calculation formula; wherein, the track tracking calculation formula includes: ; Wherein, the The trajectory tracking index value is represented, The weighted value representing the path error, being a constant, The weighted value representing the directional error is a constant.
6. 6. The gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to claim 4, wherein the steering burden index value is calculated based on a steering wheel acceleration and a steering wheel moment, comprising: inputting the acceleration of the steering wheel into a preset busy degree calculation formula to obtain the busy degree output by the busy degree calculation formula; wherein, the formula for calculating the busyness degree comprises: ; Wherein, the Indicating the degree of busyness of the user, The total length of time the vehicle is traveling is indicated, Indicating the steering wheel acceleration at time t, The standard value of the acceleration of the steering wheel is represented as a constant; Inputting the moment of the steering wheel into a preset heaviness degree calculation formula to obtain the heaviness degree output by the heaviness degree calculation formula; wherein the heaviness calculation formula includes: ; Wherein, the Indicating the degree of heaviness and, The steering wheel torque at time t is indicated, The standard value of the moment of the steering wheel is represented as a constant; inputting the busy degree and the heavy degree into a preset manipulation burden calculation formula to obtain a manipulation burden index value output by the manipulation burden calculation formula; wherein the manipulation burden calculation formula includes: ; Wherein, the Represents the manipulation burden index value, The weight value representing the degree of busyness, is a constant, The weight value representing the degree of heaviness is constant.
7. 7. The gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to claim 4, wherein the rollover index value is calculated based on the lateral acceleration and the roll angle, comprising: Inputting the lateral acceleration into a preset lateral acceleration condition calculation formula to obtain a lateral acceleration condition output by the lateral acceleration condition calculation formula; the lateral acceleration condition calculation formula comprises: ; Wherein, the Indicating the condition of lateral acceleration, The total length of time the vehicle is traveling is indicated, The lateral acceleration at time t is indicated, The standard value of lateral acceleration is expressed as a constant; inputting the roll angle into a preset roll condition calculation formula to obtain the roll condition output by the roll condition calculation formula; Wherein the roll condition calculation formula includes: ; Wherein, the Indicating a roll condition of the vehicle, The roll angle at time t is indicated, Representing the standard value of the roll angle as a constant; inputting the lateral acceleration condition and the rolling condition into a preset rollover risk calculation formula to obtain a rollover index value output by the rollover risk calculation formula; The side-turning danger calculation formula comprises: ; Wherein, the Indicating the rollover index value, The weight, which represents the lateral acceleration, is a constant, The weight value representing the roll condition is constant.
8. 8. The gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm according to claim 4, wherein the sideslip index value is calculated based on a lateral force applied to a front axle, a front axle load, a lateral force applied to a rear axle, and a rear axle load, comprising: Inputting the lateral force born by 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; the front axle sideslip risk calculation formula comprises: ; Wherein, the Indicating the risk value of the front axle sideslip, The total length of time the vehicle is traveling is indicated, Indicating the lateral force to which the front axle is subjected at time t, The front axle load at time t is indicated, Represents the lateral adhesion coefficient, which is constant; inputting the lateral force born by 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; The rear axle sideslip risk calculation formula comprises: ; Wherein, the Represents the risk value of the sideslip of the rear axle, Indicating the lateral force to which the rear axle is subjected at time t, The rear axle load at time t is indicated, Represents the lateral adhesion coefficient, which is constant; inputting the front axle sideslip dangerous value and the rear axle sideslip dangerous value into a preset sideslip dangerous calculation formula to obtain sideslip index values output by the sideslip dangerous calculation formula; wherein, the sideslip risk calculation formula includes: ; Wherein, the Indicating the sideslip index value.
9. 9. A method for determining a gear ratio of a steering-by-wire system based on a cuckoo algorithm according to any one of claims 1 to 3, wherein obtaining a front-wheel steady-state yaw-rate gain value based on the operation data comprises: inputting the longitudinal speed of the vehicle into a gain value calculation formula to obtain a front wheel steady-state yaw rate gain value output by the gain value calculation formula; the gain value calculation formula comprises: ; Wherein, the Indicating the front wheel steady-state yaw rate gain value, Indicating the longitudinal speed of the vehicle, Represents the sum of the distance from the front wheel to the center of gravity of the vehicle and the distance from the rear wheel to the center of gravity of the vehicle, The vehicle stability factor is represented as a constant.

Description

Transmission ratio determining method of drive-by-wire steering system based on cuckoo algorithm Technical Field The application relates to the technical field of electric automobile steering control, in particular to a transmission ratio determining method of a drive-by-wire steering system based on a cuckoo algorithm. Background In recent years, rapid developments in the electric automobile industry have brought about an increased demand for advanced driving assistance system technology, where automobile stability is particularly critical. In conventional automobiles, the steering system relies on a fixed mechanical gear ratio, but this limits the ability of the vehicle to adjust performance at different speeds, making it difficult to meet both sensitivity at low speeds and stability requirements at high speeds. In contrast, the steer-by-wire system adopted by the electric automobile abandons the physical connection between the steering wheel and the steering wheel, and the steering uses an electronic control system. The steering-by-wire system is an advanced automobile steering technology, and particularly controls the steering of an automobile through electronic signals, rather than traditional mechanical or hydraulic connection. The drive-by-wire steering system can automatically design the transmission ratio, and can improve the stability and the driving comfort of the vehicle under various driving conditions. Therefore, optimization and adjustment of the transmission ratio take an important role in the design of a steer-by-wire system, and become a key direction of the research on the steering technology of the electric automobile. In the prior art, the design of the variable angle transmission ratio of the steer-by-wire system adopts fuzzy control or an ideal transmission ratio which is not influenced by steering wheel angles, but the transmission ratio of the design mode is poor in smoothness and accuracy, so that poor stability of vehicle running and poor driving comfort experience are caused. Disclosure of Invention The inventor aims at the problems and the technical requirements, and provides a transmission ratio determining method of a drive-by-wire steering system based on a cuckoo algorithm, which is used for solving the problems of poor smoothness and poor precision in the prior art when determining the transmission ratio of the drive-by-wire steering system, realizing the improvement of the smoothness and the precision of determining the transmission ratio, and further improving the driving stability and the driving comfort of a vehicle. The embodiment of the application provides a transmission ratio determining method of a drive-by-wire steering system based on a cuckoo algorithm, which comprises the following steps: Acquiring operation data of a vehicle; based on the operation data, obtaining a front wheel steady yaw rate gain value and a vehicle stability evaluation index value; 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 change range based on the maximum transmission ratio, the minimum transmission ratio and the assumed center ratio; obtaining a gear ratio curved surface diagram based on the gear ratio change range, the minimum gear ratio, the assumed center ratio and the operation data; optimizing the steady-state yaw rate gain value and the center ratio of the steering wheel corresponding to each speed segment based on a cuckoo algorithm and the vehicle stability evaluation index value to obtain a target steady-state yaw rate gain value and a target center ratio of the steering wheel corresponding to each speed segment, wherein the speed segments are obtained based on the speed of the vehicle; And smoothing the steady-state yaw rate gain value of the target steering wheel and the target center ratio to obtain a target transmission ratio curved surface diagram, wherein the target transmission ratio curved surface diagram is used for representing the corresponding relation between the motion data and the transmission ratio. According to an embodiment of the present application, a gear ratio determining method of a steering-by-wire system based on a cuckoo algorithm, obtains a maximum gear ratio and a minimum gear ratio based on the front wheel steady-state yaw rate gain value and the assumed steering wheel steady-state yaw rate gain value, and obtains a gear ratio variation range based on the maximum gear ratio, the minimum gear ratio and the assumed center ratio, including: obtaining a maximum transmission ratio 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; the maximum transmission ratio calculation formula comprises: Wherein H high represents the maximum transmission rat