Vehicle rack force estimation method and system, vehicle and electronic equipment

Abstract

The invention relates to a rack force estimation method and system of a vehicle, the vehicle and electronic equipment, and relates to the technical field of vehicles, the method comprises the steps that driving information of the vehicle is acquired, and the driving information comprises a driving torque and an actual value of a target parameter; the target parameter is a gear rotation angle or a rack linear speed; obtaining a first estimated rack force at the target moment based on the driving torque, the actual value of the target parameter and a first rack force estimation model; wherein the first rack force estimation model is a rack force estimation model for a steer-by-wire system of the vehicle; under the condition that the difference value between the actual value of the target parameter and the estimated value of the target parameter at the target moment is greater than the preset difference value, determining a second estimated rack force at the target moment by utilizing a second rack force estimation model; wherein the second rack force estimation model is a rack force estimation model for the whole vehicle; and determining the output rack force of the vehicle at the target moment based on the second estimated rack force so as to improve the rack force estimation precision.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and particularly to the field of steer-by-wire systems for vehicles, specifically to a method, system, vehicle, and electronic equipment for estimating rack force. Background Technology

[0002] Currently, with the rapid development of vehicle intelligence and steer-by-wire, the use of steer-by-wire systems is increasing day by day. Steer-by-wire systems are gradually replacing traditional electric steering systems that require mechanical connection. However, because steer-by-wire systems lack the mechanical connection between the steering wheel and the vehicle's tires, the driver's perception of the vehicle's driving status becomes worse. Therefore, it is necessary to estimate the rack force of the vehicle so that the driver can perceive a more realistic road condition.

[0003] Currently, when estimating the rack force of a vehicle, a rack force estimation model for steer-by-wire systems is usually used. However, the rack force estimation model for steer-by-wire systems is generally a simplified model. Under different road conditions, the performance of the simplified model varies, which in turn affects the performance and stability of the steering system. Summary of the Invention

[0004] This invention provides a method, system, vehicle, and electronic device for estimating rack force in a vehicle, to at least solve the technical problem of rack force estimation deviation in related technologies. The technical solution adopted in this application is as follows: In a first aspect, this application provides a method for estimating the rack force of a vehicle, comprising: acquiring driving information of the vehicle, wherein the driving information includes actual values ​​of driving torque and target parameters; the target parameters are gear rotation angle or rack linear velocity; obtaining a first estimated rack force at a target time based on the driving torque, the actual values ​​of the target parameters, and a first rack force estimation model; wherein the first rack force estimation model is a rack force estimation model for the vehicle's steer-by-wire system; the target time is the control time at which the vehicle is about to enter; if the difference between the actual value of the target parameter and the estimated value of the target parameter at the target time is greater than a preset difference, determining a second estimated rack force at the target time using a second rack force estimation model; wherein the second rack force estimation model is a rack force estimation model for the entire vehicle; the estimated value of the target parameter is the parameter value of the target parameter corresponding to the first estimated rack force; and determining the output rack force of the vehicle at the target time based on the second estimated rack force.

[0005] Based on the above technical means, by comparing the actual value and the estimated value of the target parameter, the difference between the actual value and the estimated value is determined. If the difference is greater than the preset difference, the rack force estimation model for the vehicle's steer-by-wire system is selected to compensate for the local error from the perspective of the vehicle as a whole, taking into account the cumulative error of the rack force estimation model. This can utilize the vehicle's dynamic characteristics to compensate for the local error from the perspective of the vehicle as a whole, reduce the risk of deviation in rack force estimation, and ensure the estimation accuracy of rack force.

[0006] In one possible implementation, the method further includes: determining the output rack force of the vehicle at the target time based on the first estimated rack force when the difference is less than or equal to a preset difference.

[0007] Based on the above technical means, by comparing the actual value and the estimated value of the target parameter, the difference between the actual value and the estimated value is determined. When the difference is less than or equal to the preset difference, the model estimation performance of the rack force estimation model for the vehicle's steer-by-wire system is higher and the rack force estimation is more efficient. Therefore, when the difference is less than or equal to the preset difference, the first rack force estimation model can capture the change of rack force more quickly and accurately, so as to output the estimated rack force of the vehicle more efficiently.

[0008] In one possible implementation, when the difference between the actual value of the target parameter and the estimated value of the target parameter at the target time is greater than a preset difference, the second estimated rack force at the target time is determined using the second rack force estimation model, including: when the duration of the difference being greater than the preset difference is greater than a preset duration, the second estimated rack force at the target time is determined using the second rack force estimation model.

[0009] Based on the above technical means, this application avoids instantaneous deviations caused by external interference and other factors when the duration of the difference between the actual value and the estimated value of the target parameter is greater than the preset duration, thus ensuring the accuracy of rack force estimation.

[0010] In one possible implementation, the first rack force estimation model includes: a state-space model and a state observer; the state-space model is a mathematical model with the actual values ​​of the driving torque and the target parameters as observations and the rack force as an estimator; the state observer is used to solve for the estimators in the state-space model.

[0011] Based on the above technical means, this application utilizes a state-space model to more accurately describe the system changes of the steer-by-wire system, uses a state observer to estimate unmeasurable states in a timely manner, and combines the state-space model and the state observer for rack force estimation, which can improve the estimation accuracy of the first rack force estimation model, and at the same time effectively suppress noise interference and improve the reliability of rack force estimation.

[0012] In one possible implementation, the second estimated rack force at the target time is determined using a second rack force estimation model, including: acquiring vehicle operating information and inherent information; wherein, the operating information includes steering axle load, steering axle angle, vehicle speed, and self-steering gradient; and the inherent information includes aerodynamic trail, effective steering arm length, and steering axle wheelbase; and the second estimated rack force at the target time is determined based on the operating information, inherent information, and a mathematical model for calculating the whole vehicle rack force.

[0013] Based on the above technical means, this application obtains the vehicle's operating information and inherent information, and inputs them into the second rack force estimation model to estimate the rack force. This allows for the estimation of the rack force from the perspective of the vehicle as a whole, thereby utilizing the vehicle's dynamic characteristics to compensate for local errors from the perspective of the vehicle as a whole and improve the accuracy of rack force estimation.

[0014] In one possible implementation, the target estimated rack force is either a first estimated rack force or a second estimated rack force; based on the target estimated rack force, the output rack force of the vehicle at the target time is determined, including: determining a first rack force compensation value based on the rack force difference between the vehicle's actual rack force and the target estimated rack force; the first rack force compensation value is used to perform phase lead compensation on the rack force; and the output rack force is determined based on the target estimated rack force and the first rack force compensation value.

[0015] Based on the above-mentioned technical means, this application can reduce the output error caused by the lag of the rack force by compensating for the phase advance of the rack force, thereby improving the accuracy of the output rack force.

[0016] In one possible implementation, determining the output rack force based on the target estimated rack force and the first rack force compensation value includes: determining the friction force of the vehicle; determining the second rack force compensation value based on the friction force; the second rack force compensation value being used to compensate for the friction force of the rack force; and determining the output rack force based on the target estimated rack force, the first rack force compensation value, and the second rack force compensation value.

[0017] Based on the above-mentioned technical means, this application combines the vehicle's friction force to estimate the rack force compensation, which can reduce the vehicle's friction interference, make the output rack force closer to the actual load, avoid friction misjudgment, and improve the steering wheel's handling feel.

[0018] Secondly, this application provides a rack force estimation system for a vehicle, comprising: an information acquisition module for acquiring driving information of the vehicle, wherein the driving information includes actual values ​​of driving torque and target parameters; the target parameters are gear angle or rack linear velocity; a first estimation module for obtaining a first estimated rack force at a target time based on the driving torque, the actual values ​​of the target parameters, and a first rack force estimation model; wherein the first rack force estimation model is a rack force estimation model for the vehicle's steer-by-wire system; the target time is the control time the vehicle is about to enter; a second estimation module for determining a second estimated rack force at the target time using a second rack force estimation model when the difference between the actual value of the target parameters and the estimated value of the target parameters at the target time is greater than a preset difference; wherein the second rack force estimation model is a rack force estimation model for the entire vehicle; the estimated value of the target parameters is the parameter value of the target parameters corresponding to the first estimated rack force; and a rack force output module for determining the output rack force of the vehicle at the target time based on the second estimated rack force.

[0019] In one possible implementation, the system is used to determine the output rack force of the vehicle at a target time based on a first estimated rack force, provided that the difference is less than or equal to a preset difference.

[0020] In one possible implementation, the second estimation module is specifically used to determine the second estimated rack force at the target time by using the second rack force estimation model when the duration of the difference being greater than the preset difference is greater than the preset duration.

[0021] In one possible implementation, the first rack force estimation model includes: a state-space model and a state observer; the state-space model is a mathematical model with the actual values ​​of the driving torque and the target parameters as observations and the rack force as an estimator; the state observer is used to solve for the estimators in the state-space model.

[0022] In one possible implementation, the second estimation module is further used to acquire vehicle operating information and inherent information; wherein, the operating information includes steering axle load, steering axle angle, vehicle speed and self-steering gradient; the inherent information includes aerodynamic trail, steering arm length and steering axle wheelbase; and the second estimated rack force at the target time is determined based on the operating information, inherent information and a mathematical model for calculating the rack force of the whole vehicle.

[0023] In one possible implementation, the target estimated rack force is either a first estimated rack force or a second estimated rack force; the system is used to determine a first rack force compensation value based on the rack force difference between the actual rack force of the vehicle and the target estimated rack force; the first rack force compensation value is used to perform phase advance compensation on the rack force; and the output rack force is determined based on the target estimated rack force and the first rack force compensation value.

[0024] In one possible implementation, the system is further used to determine the friction force of the vehicle; based on the friction force, determine a second rack force compensation value; the second rack force compensation value is used to compensate the rack force for friction; and based on the target estimated rack force, the first rack force compensation value, and the second rack force compensation value, determine the output rack force.

[0025] Thirdly, this application provides a vehicle, including the rack force estimation system for the vehicle described in the second aspect.

[0026] Fourthly, this application provides an electronic device, including: a processor and a memory, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by the processor to implement the method described in the first aspect and any possible implementation thereof.

[0027] Fifthly, this application provides a computer-readable storage medium that, when the instructions in the computer-readable storage medium are executed by a processor of an electronic device, enables the electronic device to perform the methods described in the first aspect and any possible implementation thereof.

[0028] In a sixth aspect, this application provides a computer program product comprising computer instructions that, when executed on an electronic device, cause the electronic device to perform the method described in the first aspect and any of its possible implementations.

[0029] It should be noted that the technical effects of any of the implementation methods in aspects two through six can be found in the technical effects of the corresponding implementation methods in aspect one, and will not be repeated here.

[0030] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application, and do not constitute an undue limitation of this application.

[0032] Figure 1 This is a schematic diagram of the structure of a vehicle shown in an embodiment of this application; Figure 2 This is a flowchart illustrating a method for estimating the rack force of a vehicle according to an embodiment of this application; Figure 3 This is a block diagram illustrating a vehicle's steer-by-wire system according to an embodiment of this application; Figure 4 This is a schematic diagram illustrating a rack force estimation based on a steer-by-wire system according to an embodiment of this application; Figure 5 This is a block diagram illustrating a rack force estimation system for a vehicle according to an embodiment of this application; Figure 6 This is a block diagram illustrating an electronic device according to an embodiment of this application. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0034] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0035] In the embodiments of this application, the words "exemplary," "for example," or "for instance" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the words "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a specific manner.

[0036] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0037] The rack force estimation method for vehicles provided in this application is used to provide more accurate rack force information for simulating the steering wheel feel of vehicles (especially intelligent driving vehicles). Vehicles can also be referred to as vehicles, mobile carriers, electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles (FCVs), autonomous vehicles, intelligent and connected vehicles (ICVs), driverless vehicles, etc.

[0038] In this application, the vehicle can be a sedan, a sport utility vehicle (SUV), a truck, a special vehicle (such as an ambulance, fire truck, police car, etc.), a driverless taxi, a smart connected bus, an autonomous logistics vehicle, an electric truck, etc. Furthermore, this method is also applicable to various special-purpose vehicles, such as agricultural vehicles, mining vehicles, forestry vehicles, airport vehicles, and port vehicles. This application does not impose specific limitations in this regard.

[0039] Figure 1 This is a schematic diagram of the structure of a vehicle shown in an embodiment of this application, such as... Figure 1 As shown, the vehicle 100 of this application includes a rack force estimation system 101 and a steering control system 102. Both the rack force estimation system 101 and the steering control system 102 can be deployed in the vehicle, and the rack force estimation system 101 can also be deployed outside the vehicle.

[0040] The vehicle rack force estimation system 101 is used to input the vehicle's driving torque and target parameters into the first rack force estimation model to obtain the estimated values ​​of the first estimated rack force and the target parameters, and to determine the difference between the estimated value of the target parameters and the actual value of the target parameters. If the difference is greater than the preset difference, the second rack force estimation model is used to determine the second estimated rack force, thereby determining the output rack force for output to control the steering control system 102.

[0041] The vehicle rack force estimation system 101 is also used to determine the output rack force based on the first estimated rack force and output it to control the steering control system 102 when the difference between the estimated value and the actual value of the target parameter is less than or equal to a preset difference.

[0042] The steering control system 102 is used to adjust the output torque of the vehicle's drive motor in real time based on the output rack force of the vehicle's rack force estimation system 101 at the target time. When the rack force increases, the electric power steering system increases the motor assistance to reduce the driver's steering burden.

[0043] The steering control system 102 is also used to feed back road feedback information and the output rack force of the vehicle's rack force estimation system 101 to the driver through the steering wheel, so that the driver can simulate the feel of the steering wheel and increase the driver's steering control of the vehicle.

[0044] For example, when turning on a wet or slippery surface, changes in rack force trigger the electric power steering system to adjust the assist curve, allowing the driver to perceive a clearer steering resistance.

[0045] In practical applications, the vehicle's rack force estimation system 101 can communicate with one or more steering control systems 102.

[0046] For ease of understanding, this application uses the communication connection between a vehicle rack force estimation system 101 and a steering control system 102 as an example for illustration.

[0047] As a feasible approach, Figure 1 The rack force estimation system 101 and steering control system 102 of the vehicle are installed in the vehicle. The rack force estimation system 101 and steering control system 102 can be functional modules integrated in the same device, or they can be independently installed devices. This application does not impose any limitations on the comparison.

[0048] It is easy to understand that when the vehicle's rack force estimation system 101 and steering control system 102 are functional modules integrated within the same device, the communication method between the vehicle's rack force estimation system 101 and steering control system 102 is the same as communication between modules within the device. In this case, the communication process between the two is the same as the "communication process when the vehicle's rack force estimation system 101 and steering control system 102 are set up independently". For ease of understanding, this application mainly uses the example of the vehicle's rack force estimation system 101 and steering control system 102 being set up independently for explanation.

[0049] As a feasible approach, Figure 1 The rack force estimation system 101 for vehicles can be set on a terminal, a server, or other types of electronic devices.

[0050] When the rack force estimation system 101 for a vehicle is located at a terminal, the terminal can be a device providing data connectivity to vehicle users or owners, a handheld device with wireless connectivity, or other processing devices connected to a wireless modem. The terminal can communicate with one or more core networks via a radio access network (RAN). The terminal can be a mobile terminal, such as a computer with a mobile terminal, or a mobile device that exchanges voice and / or data with the RAN, such as a mobile phone, tablet, laptop, netbook, or personal digital assistant (PDA). This application does not impose any limitations on this.

[0051] When the rack force estimation system 101 for a vehicle is located on a server, the server can be a single server or a server cluster consisting of multiple servers. In some embodiments, the server cluster can also be a distributed cluster. This application does not impose any limitations in this regard.

[0052] It should be noted that the structure illustrated in this application embodiment does not constitute a limitation on the rack force estimation system 101 for a vehicle. It may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of both.

[0053] For ease of understanding, the rack force estimation method for vehicles provided in this application will be described in detail below with reference to the accompanying drawings.

[0054] Figure 2 This is a flowchart illustrating a method for estimating the rack force of a vehicle according to an embodiment of this application, with reference to... Figure 2 The method includes: S201. Obtain the vehicle's driving information, which includes the actual values ​​of the driving torque and the target parameter; the target parameter is the gear angle or rack linear velocity.

[0055] The aforementioned driving information is a core set of data in the vehicle's powertrain system used to describe the power transmission and execution status, including driving torque, gear angle, rack linear velocity, etc.

[0056] The aforementioned driving torque refers to the torque output by the vehicle's engine or motor, which, after being transmitted through the transmission system to the vehicle's drive wheels, generates the torque necessary to overcome road resistance and accelerate or maintain the vehicle's operation.

[0057] In a steering-by-wire system, the aforementioned driving torque is output through a motor to assist the steering wheel in turning.

[0058] The aforementioned driving torque is distributed to the front and / or rear axles of the vehicle according to the vehicle's driving needs, in order to improve the vehicle's passability under different road conditions.

[0059] The aforementioned gear rotation angle refers to the angle by which a vehicle's gear rotates around its axis. When the vehicle's steering wheel is turned, the input shaft drives the gear to rotate, and the gear rotation angle directly determines the linear displacement of the rack, thereby controlling the steering angle of the wheels.

[0060] The rack linear velocity mentioned above is the instantaneous speed at which the rack moves along the axial direction during steering. The unit of rack linear velocity is usually meters per second or millimeters per second. The higher the rack linear velocity, the faster the wheels steer and the more agile the vehicle is.

[0061] S202. Based on the actual values ​​of the driving torque, the target parameters, and the first rack force estimation model, the first estimated rack force at the target time is obtained; wherein, the first rack force estimation model is a rack force estimation model for the vehicle's steer-by-wire system.

[0062] The target time mentioned above is the control time that the vehicle is about to enter, that is, the next control time adjacent to the current control time.

[0063] The aforementioned first rack force estimation model is a mathematical model used to describe the mechanical structure and dynamic characteristics of a steer-by-wire system. For example, the first rack force estimation model includes the rack and pinion steering model, the steer-by-wire model, etc.

[0064] The first estimated rack force mentioned above is the estimated rack force of the vehicle obtained by inputting the actual values ​​of the driving torque and the target parameters into the first rack force estimation model.

[0065] The aforementioned steer-by-wire system refers to a steering technology without mechanical connection, which uses electronic signals to replace the mechanical rotation in existing steering systems, thereby decoupling the steering wheel input from the wheel steering.

[0066] The aforementioned steer-by-wire system includes a steering wheel actuator, a steering actuator, an electronic control unit, and a communication network.

[0067] S203. If the difference between the actual value of the target parameter and the estimated value of the target parameter at the target time is greater than the preset difference, the second estimated rack force at the target time is determined using the second rack force estimation model; wherein, the second rack force estimation model is a rack force estimation model for the entire vehicle.

[0068] The estimated values ​​of the target parameters mentioned above are the parameter values ​​of the target parameters corresponding to the first estimated rack force.

[0069] The above actual values ​​refer to the actual values ​​of the target parameters obtained based on preset sensor data collection or calculation.

[0070] The above-mentioned estimated value refers to the estimated value of the target parameter corresponding to the first estimated rack force obtained when the actual value of the target parameter is input into the first rack force estimation model and the first estimated rack force is estimated.

[0071] The aforementioned preset difference is a critical difference used to determine whether the deviation between the estimated and actual values ​​of the target parameter affects the rack force estimation result. If the difference between the estimated and actual values ​​is greater than the preset difference, the first estimated rack force has a large deviation, which will affect the rack force estimation result. Therefore, rack force estimation needs to be performed based on the second rack force estimation model. If the difference between the estimated and actual values ​​is less than or equal to the preset difference, the first estimated rack force has a small deviation and will not affect the rack force estimation result. Therefore, rack force estimation is performed based on the first rack force estimation model.

[0072] The aforementioned second rack force estimation model is a mathematical model used to describe the dynamic characteristics of a vehicle. For example, the second rack force estimation model can be a whole vehicle model, a tire model, a PT1 dynamic transfer function model, etc.

[0073] S204. Based on the second estimated rack force, determine the output rack force of the vehicle at the target time.

[0074] In one possible implementation, the method further includes: determining the output rack force of the vehicle at the target time based on the first estimated rack force when the difference is less than or equal to a preset difference.

[0075] The output rack force is determined by either a first estimated rack force estimated based on a first rack force estimation model or a second estimated rack force estimated based on a second rack force estimation model.

[0076] Based on the aforementioned technical means, by comparing the actual and estimated values ​​of the target parameters, the difference between the actual and estimated values ​​is determined. If the difference is greater than a preset difference, considering the error accumulation of the rack force estimation model for the vehicle's steer-by-wire system, a rack force estimation model for the entire vehicle is selected. This utilizes the vehicle's dynamic characteristics to compensate for local errors from the perspective of the entire vehicle, reducing the risk of deviation in rack force estimation and ensuring the accuracy of rack force estimation. If the difference is less than or equal to the preset difference, the first rack force estimation model can more quickly and accurately capture the changes in rack force, thereby outputting the estimated rack force of the vehicle more efficiently.

[0077] In one possible implementation, if the difference between the actual value of the target parameter and the estimated value of the target parameter at the target time is greater than a preset difference, the second estimated rack force at the target time is determined using the second rack force estimation model. This includes: if the duration of the difference being greater than the preset difference is greater than a preset duration, the second estimated rack force at the target time is determined using the second rack force estimation model to ensure the accuracy of the rack force estimation.

[0078] The aforementioned duration refers to the period during which the difference between the actual and estimated values ​​of the target parameter is greater than the preset difference for a continuous time period.

[0079] The preset duration is determined based on the estimation accuracy of the rack force. The higher the estimation accuracy of the rack force, the shorter the preset duration; the lower the estimation accuracy of the rack force, the longer the preset duration.

[0080] In one possible implementation, the first rack force estimation model includes: a state-space model and a state observer; the state-space model is a mathematical model with the actual values ​​of the driving torque and the target parameters as observations and the rack force as an estimator; the state observer is used to solve for the estimators in the state-space model.

[0081] The aforementioned state-space model is a mathematical model used to describe the dynamic relationship between the internal state and input / output variables of the first rack force estimation model. It is described by both state equations and output equations.

[0082] The aforementioned state observer is a dynamic system that uses input and output data to estimate unmeasured state variables. In the first rack force estimation model, the rack force cannot be directly measured and needs to be estimated through the state observer.

[0083] As an feasible approach, the determination of the state-space model of the first rack force estimation model includes: The differential equation of the controlled object can be simplified to: ; The state equations are converted as follows: ; ; The output equation is as follows: ; ; in, It is the actual driving torque. It is the gear angle. It outputs rack force. B is the equivalent rack moment of inertia, and B is the equivalent system damping coefficient. It is the angular velocity of the turning angle. It is angular acceleration. It is the rate of change of the output rack force over time.

[0084] The above It is a comprehensive vector used to characterize the rack motion state and the output rack force. These are observable variables used for verification, including gear rotation angle, rack linear velocity, etc.

[0085] As one possible approach, the state observer includes a gain matrix.

[0086] A state observer with a gain matrix can be represented as: ; As one possible approach, the aforementioned gain matrix L can be determined through pole placement, linear quadratic Gaussian control (LQG), or other methods.

[0087] The LQG described above is a method to optimize control performance by combining Kalman filtering and linear quadratic regulators. Its core lies in achieving accurate solution of the gain matrix through state estimation and feedback control.

[0088] The above pole configuration is a control method that optimizes the stability and sensitivity of steering response by adjusting the pole positions of the closed-loop system.

[0089] In one possible implementation, a second estimated rack force at a target time is determined using a second rack force estimation model. This includes: acquiring vehicle operating information and inherent information; wherein the operating information includes steering axle load, steering axle angle, vehicle speed, and self-steering gradient; and the inherent information includes aerodynamic trail, effective steering arm length, and steering axle wheelbase. Based on the operating information, inherent information, and a mathematical model for calculating the rack force of the entire vehicle, the second estimated rack force at the target time is determined to compensate for local errors from the perspective of the vehicle as a whole by utilizing the vehicle's dynamic characteristics.

[0090] The above-mentioned operational information refers to the dynamic parameter information that changes in real time during the vehicle's operation.

[0091] The aforementioned steering shaft load is the vertical load borne by the steering shaft, that is, the amount of vehicle weight distributed on the steering shaft, where the steering shaft is generally the front axle.

[0092] The aforementioned steering shaft angle is the steering angle of the steering shaft relative to the longitudinal axis of the vehicle, which is determined based on the steering wheel angle through the steering gear ratio.

[0093] The speed mentioned above refers to the vehicle's current speed, usually longitudinal speed.

[0094] The aforementioned self-steering gradient is a parameter used to describe the automatic steering effect of a vehicle caused by lateral acceleration or tire slip angle.

[0095] The aforementioned vehicle-specific information refers to the vehicle's static parameters, which reflect the vehicle's structure and physical characteristics.

[0096] The aforementioned aerodynamic trail distance is the lateral distance between the tire contact point and the point of application of the lateral force. The greater the aerodynamic trail distance, the greater the steering resistance.

[0097] The aforementioned effective steering arm length refers to the vertical distance from the center of the steering knuckle to the point of action of the rack.

[0098] The aforementioned steering axle wheelbase refers to the longitudinal distance from the vehicle's steering axle to the rear axle, where the steering axle is the front axle.

[0099] The above mathematical model is a method for estimating rack force using equations or formulas based on vehicle operating information and inherent information.

[0100] As an feasible approach, the process of obtaining the second estimated rack force based on the mathematical model for calculating the rack force of the entire vehicle is as follows: ; ; in, The steering resistance torque of the tire. For the second estimation of rack force, For steering axle load, For steering axis angle, For pneumatic trail, For the effective turning arm length, For vehicle speed, This refers to the wheelbase of the steering axle. Self-steering gradient = , Let be the characteristic velocity, where the characteristic velocity represents the velocity related to the deformation rate.

[0101] In one possible implementation, the target estimated rack force is either a first estimated rack force or a second estimated rack force; based on the target estimated rack force, the output rack force of the vehicle at the target time is determined, including: determining a first rack force compensation value based on the rack force difference between the vehicle's actual rack force and the target estimated rack force; the first rack force compensation value is used to perform phase lead compensation on the rack force; based on the target estimated rack force and the first rack force compensation value, the output rack force is determined to reduce the output error caused by rack force lag.

[0102] The actual rack force mentioned above refers to the actual force on the rack, which is generated by the interaction between the tire and the ground, friction of the steer-by-wire system, inertial force, etc.

[0103] The aforementioned first rack force compensation value is determined based on the difference between the actual rack force of the vehicle and the target estimated rack force, and is the value that requires rack force compensation for the target estimated rack force.

[0104] The aforementioned phase advance compensation refers to the phase delay between the actual rack force and the target estimated rack force. For example, when a vehicle is making a high-speed turn, due to the inertia or delay of the steering system, the response of the actual rack force may lag behind the steering wheel input, resulting in understeer or oversteer. Therefore, phase compensation is needed to advance the control signal so that the phase of the actual rack force matches the phase of the target estimated rack force.

[0105] As one possible approach, the first rack force compensation value is used to compensate for the phase lag of the rack force.

[0106] The output rack force mentioned above is the result of adding the target estimated rack force to the first rack force compensation value.

[0107] As one possible approach, the first rack force compensation value can be determined using a compensator to perform phase hysteresis correction.

[0108] The formula for calculating the transfer function of the above compensator is as follows: ; Where K is the gain coefficient. For complex frequency variables, For molecular zero-point parameters, These are molecular pole parameters. > >0.

[0109] The transfer function described above reflects the proportional relationship between the input and output of the first rack force estimation model and / or the second rack force estimation model in the complex frequency domain.

[0110] As an alternative approach, if road feedback is not required during the debugging process of the steer-by-wire system, phase advance compensation can be stopped by adjusting the parameters K, a, and b in the aforementioned transfer function.

[0111] When adjusting the parameters of the transfer function, it is important to ensure that the DC gain of the compensator is at the preset gain value. This will better guarantee that the estimated rack force in the low-frequency range is not disturbed. For example, the preset gain value is 1.

[0112] In one possible implementation, the output rack force is determined based on the target estimated rack force and the first rack force compensation value, including: determining the friction force of the vehicle; determining the second rack force compensation value based on the friction force; the second rack force compensation value is used to compensate the rack force for friction; and the output rack force is determined based on the target estimated rack force, the first rack force compensation value, and the second rack force compensation value to avoid friction misjudgment.

[0113] The aforementioned frictional forces include sliding friction in the gear and rack transmission of a vehicle, roller friction, and Coulomb friction in a steer-by-wire system.

[0114] The aforementioned Coulomb friction manifests as a constant resistance opposite to the direction of motion. For example, the friction between a tubular bearing, a pressure block, and a rack is presented in Coulomb form.

[0115] The aforementioned second rack force compensation value refers to the compensation value of the vehicle's friction force for the estimated rack force.

[0116] The output rack force mentioned above is the result of subtracting the second rack force compensation value from the sum of the target estimated rack force and the first rack force compensation value.

[0117] As an feasible approach, the aforementioned friction force can be determined based on a friction model, such as the Lugre friction model. Using the Lugre friction model, combined with a speed-segmented compensation strategy, and setting a high compensation coefficient in the 0-10 km / h range, can better reflect the vehicle's tire load and improve the accuracy of rack force estimation.

[0118] As a feasible approach, Figure 3 This is a block diagram illustrating a vehicle's steer-by-wire system according to an embodiment of this application.

[0119] The vehicle's steer-by-wire system 300 mainly consists of two parts: a steering wheel actuator 301 and a steering actuator 302. The steering wheel actuator 301 and the steering actuator 302 communicate via a private controller local area network.

[0120] Figure 4 This is a schematic diagram illustrating rack force estimation based on a steer-by-wire system, as shown in an embodiment of this application. (Refer to...) Figure 4 The steer-by-wire system consists of a steering actuator and a steering wheel actuator.

[0121] The vehicle's driving information is input into the first rack force estimation model of the steering actuator; Using the first rack force estimation model, the first estimated rack force is determined, and the estimated value of the target parameter is determined; At the same time, it is determined whether the difference between the actual value of the target parameter in the driving information and the estimated value of the target parameter at the target time is greater than the preset difference. If yes, then the second estimated rack force is determined as the target estimated rack force using the second rack force estimation model; otherwise, the first estimated rack force is used as the target estimated rack force. The target estimated rack force is compensated based on the first rack force compensation value and the second rack force compensation value to obtain the output rack force; The output rack force is input to the steering wheel actuator to simulate the feel.

[0122] Figure 5 This is a block diagram illustrating a rack force estimation system for a vehicle according to an embodiment of this application, with reference to... Figure 5 The rack force estimation system for the vehicle includes: an information acquisition module 501, a first estimation module 502, a second estimation module 503, and a rack force output module 504.

[0123] The information acquisition module 501 is used to acquire the vehicle's driving information, which includes the actual values ​​of the driving torque and the target parameter; the target parameter is the gear angle or the rack linear velocity. The first estimation module 502 is used to obtain the first estimated rack force at the target time based on the actual value of the driving torque, the target parameter, and the first rack force estimation model; wherein, the first rack force estimation model is the rack force estimation model for the vehicle's steer-by-wire system; the target time is the control time that the vehicle is about to enter; The second estimation module 503 is used to determine the second estimated rack force at the target time by using the second rack force estimation model when the difference between the actual value of the target parameter and the estimated value of the target parameter at the target time is greater than a preset difference; wherein, the second rack force estimation model is a rack force estimation model for the entire vehicle; the estimated value of the target parameter is the parameter value of the target parameter corresponding to the first estimated rack force; The rack force output module 504 is used to determine the output rack force of the vehicle at the target time based on the second estimated rack force.

[0124] In one possible implementation, the system is used to determine the output rack force of the vehicle at a target time based on a first estimated rack force, provided that the difference is less than or equal to a preset difference.

[0125] In one possible implementation, the second estimation module is specifically used to determine the second estimated rack force at the target time by using the second rack force estimation model when the duration of the difference being greater than the preset difference is greater than the preset duration.

[0126] In one possible implementation, the first rack force estimation model includes: a state-space model and a state observer; the state-space model is a mathematical model with the actual values ​​of the driving torque and the target parameters as observations and the rack force as an estimator; the state observer is used to solve for the estimators in the state-space model.

[0127] In one possible implementation, the second estimation module is further used to acquire vehicle operating information and inherent information; wherein, the operating information includes steering axle load, steering axle angle, vehicle speed and self-steering gradient; the inherent information includes aerodynamic trail, steering arm length and steering axle wheelbase; and the second estimated rack force at the target time is determined based on the operating information, inherent information and a mathematical model for calculating the rack force of the whole vehicle.

[0128] In one possible implementation, the target estimated rack force is either a first estimated rack force or a second estimated rack force; the system is used to determine a first rack force compensation value based on the rack force difference between the actual rack force of the vehicle and the target estimated rack force; the first rack force compensation value is used to perform phase advance compensation on the rack force; and the output rack force is determined based on the target estimated rack force and the first rack force compensation value.

[0129] In one possible implementation, the system is further used to determine the friction force of the vehicle; based on the friction force, determine a second rack force compensation value; the second rack force compensation value is used to compensate the rack force for friction; and based on the target estimated rack force, the first rack force compensation value, and the second rack force compensation value, determine the output rack force.

[0130] Regarding the methods in the above embodiments, the specific manner in which each step is performed has been described in detail in the embodiments of the vehicle rack force estimation method, and will not be elaborated here.

[0131] Figure 6 This is a block diagram illustrating an electronic device according to an embodiment of this application. Figure 6 As shown, the electronic device includes, but is not limited to, a processor 601 and a memory 602.

[0132] The memory 602 described above is used to store the executable instructions of the processor 601. It is understood that the processor 601 is configured to execute instructions to implement the cold start method for the fuel cell in the above embodiment.

[0133] It should be noted that those skilled in the art will understand that Figure 6 The electronic device structure shown does not constitute a limitation on the electronic device; the electronic device may include, but is not limited to, other electronic devices. Figure 6 This may indicate more or fewer components, or combinations of certain components, or different component arrangements.

[0134] Processor 601 is the control center of the electronic device. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in memory 602, and by calling data stored in memory 602, it performs various functions and processes data, thereby providing overall monitoring of the electronic device. Processor 601 may include one or more processing units. Processor 601 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into processor 601.

[0135] The memory 602 can be used to store software programs and various data. The memory 602 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required by at least one functional module (such as deterministic components, integrated components, etc.), etc. Furthermore, the memory 602 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0136] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 602 including instructions, which can be executed by a processor 601 of an electronic device to implement the methods in the above embodiments.

[0137] In actual implementation, Figure 5 The functions of the information acquisition module 501, the first estimation module 502, the second estimation module 503, and the rack force output module 504 can all be derived from... Figure 6 The processor 601 calls the computer program stored in the memory 602 to implement the process. The specific execution process can be found in the description of the method section in the previous embodiment, and will not be repeated here.

[0138] Optionally, the computer-readable storage medium may be a non-transitory computer-readable storage medium, such as a read-only memory (ROM), random access memory (RAM), compact disc read-only memory (CD-ROM), magnetic tape, floppy disk, and optical data storage device. In an exemplary embodiment, this application also provides a computer program product including one or more instructions, which can be executed by the processor 601 of an electronic device to perform the methods in the above embodiments.

[0139] It should be noted that when one or more instructions in the computer-readable storage medium or computer program product are executed by the processor of the electronic device, they implement the various processes of the above method embodiments and achieve the same technical effect as the above method. To avoid repetition, they will not be described again here.

[0140] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0141] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0142] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0143] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0144] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, essentially, or the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0145] This application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the methods described in the above method embodiments.

[0146] This application also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method in the method flow shown in the above method embodiments.

[0147] The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, a register, a hard disk, an optical fiber, a portable compact disk read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof, or any other form of computer-readable storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside in an application-specific integrated circuit (ASIC). In embodiments of this application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0148] Since the vehicle rack force estimation system, computer-readable storage medium, and computer program product in the embodiments of this application can be applied to the above method, the technical effects that can be obtained can also be referred to the above method embodiments. The embodiments of this application will not be repeated here.

[0149] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A rack force estimation method of a vehicle, characterized by, The method comprises: acquiring driving information of a vehicle, wherein the driving information comprises a driving torque and an actual value of a target parameter; the target parameter is a gear rotation angle or a rack linear speed; based on the driving torque, the actual value of the target parameter and a first rack force estimation model, obtaining a first estimated rack force at a target time; wherein the first rack force estimation model is a rack force estimation model for a steer-by-wire system of the vehicle; the target time is a control time at which the vehicle is about to enter; in a case where a difference between the actual value of the target parameter and an estimated value of the target parameter at the target time is greater than a preset difference value, determining a second estimated rack force at the target time by using a second rack force estimation model; wherein the second rack force estimation model is a rack force estimation model for the vehicle as a whole; the estimated value of the target parameter is a parameter value of the target parameter corresponding to the first estimated rack force; based on the second estimated rack force, determining an output rack force of the vehicle at the target time.

2. The rack force estimation method of a vehicle according to claim 1, characterized by, The method further comprises: in a case where the difference is less than or equal to the preset difference value, determining the output rack force of the vehicle at the target time based on the first estimated rack force.

3. The rack force estimation method of a vehicle according to claim 1, characterized by, The case where the difference between the actual value of the target parameter and the estimated value of the target parameter at the target time is greater than the preset difference value, and the determination of the second estimated rack force at the target time by using the second rack force estimation model, comprises: in a case where a duration for which the difference is greater than the preset difference value is greater than a preset duration, determining the second estimated rack force at the target time by using the second rack force estimation model.

4. The rack force estimation method of a vehicle according to claim 1, characterized by, The first rack force estimation model comprises a state space model and a state observer; the state space model is a mathematical model taking the driving torque and the actual value of the target parameter as observation quantities and taking the rack force as an estimated quantity; the state observer is used to solve the estimated quantity in the state space model.

5. The rack force estimation method of a vehicle according to claim 1, characterized by, The determination of the second estimated rack force at the target time by using the second rack force estimation model comprises: acquiring running information and inherent information of the vehicle; wherein the running information comprises a steering shaft load, a steering shaft rotation angle, a vehicle speed and a self-steering gradient; the inherent information comprises an aerodynamic drag distance, a steering effective arm length and a steering shaft wheelbase; based on the running information, the inherent information and a mathematical model for calculating a rack force of the vehicle as a whole, determining the second estimated rack force at the target time.

6. The rack force estimation method of a vehicle according to claim 2, characterized by, The target estimated rack force is the first estimated rack force or the second estimated rack force; The determination of the output rack force of the vehicle at the target time based on the target estimated rack force comprises: based on a rack force difference value between an actual rack force of the vehicle and the target estimated rack force, determining a first rack force compensation value; the first rack force compensation value is used for phase-advance compensation of the rack force; based on the target estimated rack force and the first rack force compensation value, determining the output rack force.

7. The rack force estimation method of a vehicle according to claim 6, characterized by, The determination of the output rack force based on the target estimated rack force and the first rack force compensation value comprises: determining a friction force of the vehicle; determine a second rack force compensation value based on the friction force; the second rack force compensation value is used for friction force compensation of the rack force; determine the output rack force based on the target estimated rack force, the first rack force compensation value and the second rack force compensation value.

8. A rack force estimation system for a vehicle, characterized by, The system comprises: an information acquisition module configured to acquire driving information of the vehicle, wherein the driving information comprises a driving torque and an actual value of a target parameter; the target parameter is a gear rotation angle or a rack linear speed; a first estimation module configured to obtain a first estimated rack force at a target time based on the driving torque, the actual value of the target parameter and a first rack force estimation model; wherein the first rack force estimation model is a rack force estimation model for a steer-by-wire system of the vehicle; the target time is a control time at which the vehicle is about to enter; a second estimation module configured to, in a case where a difference between the actual value of the target parameter and an estimated value of the target parameter at the target time is greater than a preset difference value, determine a second estimated rack force at the target time by using a second rack force estimation model; wherein the second rack force estimation model is a rack force estimation model for the vehicle as a whole; the estimated value of the target parameter is a parameter value of the target parameter corresponding to the first estimated rack force; a rack force output module configured to determine an output rack force of the vehicle at the target time based on the second estimated rack force.

9. A vehicle characterized by comprising: The vehicle comprises the rack force estimation system of the vehicle according to claim 8.

10. An electronic device, comprising: comprise a processor and a memory, the memory storing at least one computer program, at least one computer program being loaded and executed by the processor to implement the rack force estimation method of the vehicle according to any one of claims 1 to 7.

Images