A method and system for estimating tire forces of a steered-suspension vehicle based on a kingpin steering motor

Abstract

The application discloses a kind of based on kingpin steering motor's angle module vehicle tire force estimation method and system, kingpin steering motor current, kingpin angle and vehicle acceleration signal are collected wheel movement, equivalent output torque of kingpin shaft is converted into motor current, kingpin disturbance torque caused by tire force is obtained after steering system dynamics compensation;According to the space torque projection relationship of tire force to kingpin shaft that kingpin shaft direction and tire contact point position establish, wheel rotation dynamics and load transfer model are combined to estimate tire longitudinal force, vertical force, and then inverse calculation tire lateral force, calculate adhesion utilization rate and output to vehicle control system.The application does not need additional tire force sensor, can avoid steering mechanism itself dynamics interference, adapt kingpin inward inclination, inclination and offset distance Actual geometry, improve the physical consistency and adaptability of single-wheel tire force estimation under complex working conditions, facilitate stability, trajectory tracking, anti-skid, yaw moment and fault-tolerant control call.

Description

Technical Field

[0001] This invention relates to the fields of chassis control for new energy vehicles, vehicle dynamics state estimation for corner modules, and tire force estimation, specifically to a tire force estimation method and system based on a kingpin steering motor for corner module new energy vehicles. Background Technology

[0002] As new energy vehicles develop towards electrification, drive-by-wire, and chassis integration, pure electric vehicles, hybrid electric vehicles, and fuel cell electric vehicles are increasingly adopting corner modular chassis architectures. In new energy vehicles using corner modular chassis architectures, the steering, driving, and braking functions of the wheels can be independently controlled by their respective actuators. Among these, the kingpin steering motor is used to drive the wheels to rotate around the kingpin axle. During vehicle operation, the interaction forces between the tires and the ground include longitudinal, lateral, and vertical forces. The tire forces of each wheel are crucial state information for vehicle stability control, trajectory tracking control, and drive braking force distribution; therefore, it is necessary to estimate the tire forces of each wheel.

[0003] Tire force can be directly acquired using measuring devices such as six-component force sensors, but adding these devices increases system cost and installation requirements. Indirect estimation methods utilize signals such as vehicle motion, wheel-end drive, and braking torque, combined with vehicle dynamics or tire models, to estimate tire force. However, estimations relying on tire models are susceptible to the accuracy of model parameters. Changes in tire operating conditions or road surface adhesion can reduce estimation accuracy due to deviations between the model and actual conditions.

[0004] For corner modules equipped with a kingpin steering motor, the motor current can reflect the motor output torque, providing a signal basis for analyzing the torque exerted by the tires on the steering mechanism. However, in addition to balancing the torque exerted by the tires, the output torque of the kingpin steering motor is also used to overcome the inertia, damping, and mechanical friction of the steering system itself. If the motor output torque is directly converted into the torque exerted by the tires, the dynamic influence of the steering mechanism itself can easily be introduced into the tire force estimation results.

[0005] Furthermore, steering geometry parameters such as kingpin inclination angle, caster angle, kingpin offset, and mechanical trail can affect the torque generated by the tire forces in each direction on the kingpin shaft. Tire forces in different directions may act on the kingpin shaft together. If a simplified model that does not fully consider the above spatial geometric relationships is used, or if the effects of longitudinal force, vertical force, and tire self-aligning torque are ignored, it may cause deviations in the estimation of lateral force. It is also difficult to directly distinguish the contribution of tire forces in each direction based solely on the torque on the kingpin shaft.

[0006] Therefore, how to reduce the estimation error caused by the simplification of the steering system's own dynamics and torque relationship without adding tire force sensors, and how to obtain the longitudinal force, lateral force and vertical force of each wheel using the vehicle's existing signals, is a technical problem that needs to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a method and system for estimating tire force in a vehicle based on a kingpin steering motor, in order to solve the problems of torque interference caused by the steering system's own inertia, damping and mechanical friction when estimating tire force using the kingpin steering motor signal, as well as the reduced accuracy of tire force estimation caused by insufficient consideration of the kingpin spatial geometry and tire return torque.

[0008] To achieve the above objectives, the technical solution provided by this invention is: a method for estimating tire force of a vehicle based on a kingpin steering motor, comprising the following steps: S1: Collect vehicle status signals for each wheel to be estimated, including kingpin steering motor current, kingpin angle, kingpin angular velocity, wheel angular velocity, wheel-end drive torque and wheel-end braking torque, as well as vehicle longitudinal acceleration and lateral acceleration. Perform time synchronization and filtering on the vehicle status signals, and obtain kingpin angular acceleration and wheel angular acceleration. S2: Calculate the equivalent output torque of the kingpin shaft using the kingpin steering motor current, combined with the preset motor torque constant, reducer transmission ratio, and transmission efficiency; calculate the inertial torque, damping torque, and friction torque based on the kingpin angular acceleration, kingpin angular velocity, and friction model, and subtract them from the equivalent output torque to obtain the kingpin disturbance torque caused by the tire force; S3: Under the current kingpin rotation angle, obtain the unit vector in the kingpin shaft direction and the position vector of the tire contact point relative to the reference point on the kingpin shaft. After cross-multiplying the position vector with the longitudinal, lateral and vertical unit vectors respectively, project it onto the kingpin shaft direction to obtain the equivalent force arm coefficients of the longitudinal force, lateral force and vertical force, and establish the moment projection relationship between the kingpin disturbance torque and each tire force component. S4: Based on the wheel-end driving torque, wheel-end braking torque, and wheel angular acceleration, estimate the tire longitudinal force using a wheel rotation dynamics model; based on the vehicle mass, center of gravity height, distance from the center of gravity to the front and rear axles, track width between the front and rear axles, lateral load transfer ratio between the front and rear axles, and the vehicle's longitudinal and lateral accelerations, estimate the tire vertical force using a load transfer model. S5: Substitute the kingpin disturbance torque, tire longitudinal force, and tire vertical force into the torque projection relationship, and back-calculate the tire lateral force of each wheel to be estimated using the equivalent force arm coefficient of the lateral force. Output the tire longitudinal force, tire lateral force, and tire vertical force of each wheel to be estimated, and output the adhesion utilization rate of each wheel to the vehicle control system.

[0009] To optimize the above technical solution, the specific measures also include: In step S1, the kingpin steering motor is a permanent magnet synchronous motor, and the kingpin steering motor current is the q-axis current obtained by coordinate transformation of the motor phase current; the kingpin rotational velocity is obtained directly by the rotational angle sensor or by differentially analyzing the kingpin rotational angle, and the kingpin rotational acceleration and wheel angular acceleration are obtained by differentially analyzing the kingpin rotational velocity and wheel angular velocity and then by low-pass filtering.

[0010] Further, in step S2, the equivalent output torque of the main pin shaft and the disturbance torque of the main pin are respectively expressed as:

[0011]

[0012] in, The equivalent output torque of the main pin shaft For transmission efficiency, The gear ratio of the reducer. The torque constant of the motor. The current of the master steering motor. Main pin disturbance torque The equivalent rotational inertia of the masterpipe steering system Main pin rotational speed, Main pin rotational acceleration This is the equivalent damping coefficient. It is the equivalent frictional torque obtained through calibration or friction model, and its sign varies with the direction of kingpin rotation.

[0013] In step S3, the vehicle's forward direction, left side direction, and top direction are used as the x-axis, y-axis, and z-axis of the vehicle coordinate system, respectively. A point on the kingpin axis is selected as a reference point; the unit vector of the kingpin axis direction is represented as... The position vector is represented as And the equivalent arm coefficient is expressed as:

[0014] in, , and These represent the unit components of the kingpin axis in the longitudinal, lateral, and vertical directions of the vehicle, respectively. , and These represent the components of the position vector in the longitudinal, lateral, and vertical directions of the vehicle, respectively. Main sales corner At that time, longitudinal force Equivalent force arm for the main pin shaft; Main sales corner At that time, lateral force Equivalent force arm for the main pin shaft; Main sales corner At that time, vertical force Equivalent force arm for the kingpin.

[0015] Further, in step S4, the longitudinal force of the tire is the value obtained by subtracting the braking torque at the wheel end and the product of the wheel's equivalent moment of inertia and the wheel's angular acceleration from the wheel-end driving torque, and then dividing it by the effective rolling radius of the tire; the load transfer model includes static wheel load calculation, longitudinal load transfer calculation, and lateral load transfer calculation. The static loads on the front and rear axles are calculated using the vehicle's mass, gravitational acceleration, distance from the center of gravity to the front and rear axles, and wheelbase, and the static loads on each axle are evenly distributed to the left and right wheels. The longitudinal load transfer between the front and rear axles is calculated using the vehicle's mass, center of gravity height, wheelbase, and longitudinal acceleration. The lateral load transfer between the left and right wheels on each axle is calculated using the vehicle's mass, center of gravity height, front and rear axle track width, lateral acceleration, and the lateral load transfer ratio between the front and rear axles. The static wheel loads, longitudinal load transfers, and lateral load transfers are superimposed to obtain the vertical tire force of each wheel. The lateral load transfer ratio between the front and rear axles is obtained from the front and rear suspension roll stiffness distribution relationship or calibration results, and the sum of the two is 1.

[0016] In step S5, the introduction of the tire return torque to correct the lateral force equivalent lever coefficient includes: Furthermore, using tire pneumatic drag distance The tire self-aligning torque is expressed as the offset distance between the point of application of the lateral force on the tire and the point of contact with the ground. Corrected lateral force equivalent lever coefficient:

[0017] Introducing the tire return torque into the torque projection relationship, we obtain:

[0018]

[0019] in, This is the projection coefficient of the tire return torque in the direction of the kingpin shaft; , and These are the longitudinal force, lateral force, and vertical force of the tire corresponding to the wheel; , and These are the equivalent force arm coefficients of the longitudinal force, lateral force, and vertical force on the main pin, respectively. The equivalent force arm coefficient of the lateral force after introducing the tire self-aligning torque; This represents the total disturbance torque generated around the main pin axis.

[0020] Further, in step S5, the available adhesion coefficient of the road surface where the wheel to be estimated is located is obtained. The adhesion limit constraint is set so that the resultant force of the tire longitudinal force and the tire lateral force is no greater than the product of the available adhesion coefficient and the tire vertical force. The calculated tire lateral force is then limited. The adhesion utilization rate is calculated according to the following formula:

[0021] in, To improve the utilization rate of the adhesive, The available adhesion coefficient; when the adhesion utilization rate reaches a preset threshold, the corresponding wheel is determined to be close to the adhesion limit.

[0022] As another important technical solution, the present invention also provides a tire force estimation system for corner module vehicles based on a kingpin steering motor, realizing the tire force estimation method for corner module vehicles based on a kingpin steering motor as described above, including: The signal acquisition and processing module is used to acquire vehicle status signals of each wheel to be estimated, including kingpin steering motor current, kingpin angle, kingpin angular velocity, wheel angular velocity, wheel-end drive torque and wheel-end braking torque, as well as vehicle longitudinal acceleration and lateral acceleration. It performs time synchronization and filtering on the vehicle status signals and obtains kingpin angular acceleration and wheel angular acceleration. The kingpin torque conversion and dynamic compensation module is used to convert the kingpin steering motor current, combined with the preset motor torque constant, reducer transmission ratio and transmission efficiency, into the equivalent output torque of the kingpin shaft; it calculates the inertial torque and damping torque based on the kingpin angular acceleration and kingpin angular velocity, as well as the equivalent friction torque generated by the mechanical friction inside the kingpin steering system, and subtracts it from the equivalent output torque to obtain the kingpin disturbance torque caused by the tire force; The kingpin spatial geometry mapping module is used to obtain the unit vector of the kingpin axis direction and the position vector of the tire contact point relative to the reference point on the kingpin axis under the current kingpin rotation angle. The position vector is cross-multiplied with the longitudinal, lateral and vertical unit vectors respectively and projected onto the kingpin axis direction to obtain the equivalent force arm coefficients of the longitudinal force, lateral force and vertical force, and to establish the moment projection relationship between the kingpin disturbance torque and each tire force component. The longitudinal and vertical force estimation modules are used to estimate the tire longitudinal force based on the wheel-end driving torque, wheel-end braking torque, and wheel angular acceleration using a wheel rotation dynamics model; and to estimate the tire vertical force based on the vehicle mass, center of gravity height, distance from the center of gravity to the front and rear axles, track width between the front and rear axles, lateral load transfer ratio between the front and rear axles, and the vehicle's longitudinal and lateral accelerations using a load transfer model. The lateral force back-calculation and adhesion status output module is used to substitute the kingpin disturbance torque, tire longitudinal force and tire vertical force into the torque projection relationship, introduce the tire return torque to correct the lateral force equivalent arm coefficient, back-calculate the tire lateral force of each wheel to be estimated, output the tire longitudinal force, tire lateral force and tire vertical force of each wheel to be estimated, and calculate the adhesion utilization rate of each wheel before outputting it to the vehicle control system.

[0023] The present invention also proposes an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the above-described method for estimating the tire force of a vehicle based on a kingpin steering motor.

[0024] The present invention also proposes a computer-readable storage medium storing a computer program that causes a computer to execute a method for estimating tire forces of a vehicle based on a kingpin steering motor, as described above.

[0025] Compared with the prior art, the beneficial effects of the present invention are: This invention is applicable to new energy electric vehicles, especially pure electric vehicles, hybrid electric vehicles, fuel cell electric vehicles, and other new energy electric vehicles that use corner modules and kingpin steering motors. It eliminates the need for additional six-component tire sensors or extra force sensors. It can achieve single-wheel tire force estimation using only existing signals such as kingpin steering motor current, kingpin angle, wheel angular velocity, wheel-end drive / braking torque, and vehicle longitudinal and lateral acceleration, thereby reducing system costs and simplifying structure and layout.

[0026] This invention uses dynamic compensation of the kingpin steering system to separate the kingpin disturbance torque caused by tire force from the equivalent output torque of the kingpin shaft, avoiding mistaking the inertia, damping and friction of the steering mechanism itself as tire force, thus improving the physical consistency and engineering feasibility of tire force estimation results.

[0027] This invention establishes a spatial moment projection relationship based on the spatial direction of the kingpin shaft and the tire contact point position, and uses the equivalent force arm coefficient to characterize the effect of longitudinal force, lateral force and vertical force on the kingpin shaft. It can adapt to actual steering geometry characteristics such as kingpin inclination angle, kingpin caster angle, kingpin offset and mechanical trailing distance, and improves the accuracy of lateral force back calculation.

[0028] This invention integrates wheel rotation dynamics and load transfer models to estimate the longitudinal and vertical forces of the tire, and introduces tire self-aligning torque and aerodynamic trail correction to achieve coordinated estimation of longitudinal, lateral, and vertical forces, thereby improving adaptability under complex conditions such as low adhesion, rapid acceleration, emergency braking, and extreme steering.

[0029] This invention, through adhesion limit constraints and adhesion utilization calculations, can limit the amplitude of the back-calculated lateral force and determine whether the wheel is close to the adhesion limit, providing reliable underlying state quantities for vehicle stability control, trajectory tracking control, anti-skid control, yaw moment control, and fault-tolerant control.

[0030] This invention can be applied to the whole vehicle controller of new energy electric vehicles, chassis domain controller, intelligent connected vehicle drive-by-wire chassis and corner module control system, which is conducive to the development of drive-by-wire, intelligent and integrated chassis of new energy vehicles. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the vehicle tire force estimation method based on the kingpin steering motor of the present invention.

[0032] Figure 2 This is a schematic diagram of the vehicle tire force estimation framework based on the kingpin steering motor of the present invention. Detailed Implementation

[0033] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0034] In the description of this invention, it should also be noted that: The vehicle described in this invention is applicable to new energy electric vehicles, including but not limited to pure electric vehicles, hybrid electric vehicles, and fuel cell electric vehicles; it is particularly applicable to four-wheel independent drive and independent steering angle module new energy electric vehicles. Each wheel is equipped with an independent angle module, and the kingpin steering motor is installed in the corresponding angle module, driving the wheel to rotate around the kingpin shaft through the steering transmission mechanism.

[0035] In some implementations, such as Figure 1 and Figure 2 As shown, this invention provides a method for estimating tire force in a vehicle based on a kingpin steering motor, comprising the following steps: S1: Collect vehicle status signals for each wheel to be estimated, including kingpin steering motor current, kingpin angle, kingpin angular velocity, wheel angular velocity, wheel-end drive torque and wheel-end braking torque, as well as vehicle longitudinal acceleration and lateral acceleration. Perform time synchronization and filtering on the vehicle status signals, and obtain kingpin angular acceleration and wheel angular acceleration. In some implementations, the kingpin steering motor is a permanent magnet synchronous motor, and the kingpin steering motor current is the q-axis current obtained by coordinate transformation of the motor phase current. When the kingpin steering motor is a permanent magnet synchronous motor, the q-axis current is approximately proportional to the motor output torque, and therefore can be used for subsequent kingpin torque estimation. Kingpin Corner This represents the rotation angle of the wheel relative to the vehicle body around the kingpin, obtained by an angle sensor, rotary encoder, or motor position sensor. For four-wheel independent drive or modular vehicles, the drive torque and steering angle of each wheel can be obtained independently, making it more suitable for single-wheel tire force estimation. This obtains the vehicle state signal vector. :

[0036] in, This is the current of the kingpin steering motor, used to calculate the output torque of the kingpin steering motor; The kingpin angular velocity is used to characterize how fast the steering system rotates. It is the kingpin angular acceleration, used to calculate the inertial torque of the steering system; This is the wheel angular velocity, used to estimate the tire's longitudinal force in conjunction with wheel rotational dynamics; For the wheel end driving torque, This refers to the braking torque at the wheel end. For the longitudinal acceleration of the vehicle, These are the vehicle's lateral accelerations, and are used to calculate vehicle load transfer and changes in tire vertical force. This refers to the wheel's angular acceleration.

[0037] Wheel angular velocity Wheel-end drive torque and braking torque Used to estimate tire longitudinal force Vehicle longitudinal speed Longitudinal acceleration Lateral acceleration and yaw rate Used to calculate vehicle motion state, load transfer, and tire adhesion state.

[0038] S2: Calculate the equivalent output torque of the kingpin shaft using the kingpin steering motor current, combined with the preset motor torque constant, reducer transmission ratio, and transmission efficiency; calculate the inertial torque, damping torque, and friction torque based on the kingpin angular acceleration, kingpin angular velocity, and friction model, and subtract them from the equivalent output torque to obtain the kingpin disturbance torque caused by the tire force; Equivalent output torque of the main pin shaft When direct measurement is not possible, conversion can be performed using the motor current:

[0039] Among them, the motor torque constant The transmission ratio of a reducer represents the electromagnetic torque that can be generated per unit current. This indicates the amplification relationship of the motor output torque after being referred to the main pin shaft, and the transmission efficiency. This is used to account for energy losses caused by gears, bearings, and transmission pairs.

[0040] In some implementations, the inertial torque used to accelerate the steering system, the damping torque used to overcome speed-related drag, and the frictional torque used to overcome mechanical friction are calculated based on the kingpin angular acceleration, kingpin angular velocity, and friction model. These torques are then subtracted from the equivalent output torque of the kingpin shaft to obtain the kingpin disturbance torque caused by the tire force. :

[0041] in, The equivalent rotational inertia of the masterpipe steering system This is the equivalent damping coefficient. It is the equivalent frictional torque generated by the internal mechanical friction of the kingpin steering system, used to characterize the resistance effect of bearings, seals, gear meshing pairs and other friction pairs on the rotation of the kingpin in the steering mechanism.

[0042] S3: Under the current kingpin rotation angle, obtain the unit vector in the kingpin shaft direction and the position vector of the tire contact point relative to the reference point on the kingpin shaft. After cross-multiplying the position vector with the longitudinal, lateral and vertical unit vectors respectively, project it onto the kingpin shaft direction to obtain the equivalent force arm coefficients of the longitudinal force, lateral force and vertical force, and establish the moment projection relationship between the kingpin disturbance torque and each tire force component. Since the actual vehicle kingpin is usually not perpendicular to the ground, but has a kingpin inclination angle and a kingpin caster angle, the kingpin disturbance torque cannot be calculated by simply multiplying the planar distance by the tire force. Instead, the torque vector generated by the tire contact point relative to the reference point on the kingpin should be calculated first, and then the torque vector should be projected onto the kingpin direction.

[0043] In some implementations, a vehicle coordinate system is established. Using the vehicle's forward direction, left side direction, and top of the vehicle as the x-axis, y-axis, and z-axis of the vehicle coordinate system, respectively, a point is selected on the kingpin axis as a reference point. ; , , Both represent the force exerted by the ground on the tire. Components in the vehicle coordinate system; The unit vector representing the direction of the main pin shaft is:

[0044] satisfy:

[0045] The position vector is represented as:

[0046] in, , and These represent the unit components of the kingpin axis in the longitudinal, lateral, and vertical directions of the vehicle, respectively. , and These represent the components of the position vector in the longitudinal, lateral, and vertical directions of the vehicle, respectively. According to the definition of spatial moment, ground force Reference point for the kingpin The resulting spatial torque vector is:

[0047] Expanded representation:

[0048] in, The second term represents the torque component about the vehicle's x-axis. The third term represents the torque component about the vehicle's y-axis. Represents the torque component about the vehicle's z-axis, and the reference point of the kingpin. Any point on the kingpin axis is typically chosen as the intersection of the kingpin axis and the ground.

[0049] In some implementations, since the kingpin steering motor can only sense torque about the kingpin axis, it is necessary to vectorize the spatial torque. Projected onto the unit vector in the direction of the main pin axis superior.

[0050] Kingpin disturbance torque caused by tire force:

[0051] The equivalent force arm coefficient is expressed as:

[0052] The kingpin disturbance torque caused by tire force is written as:

[0053] in, Main sales corner At that time, longitudinal force Equivalent force arm for the main pin shaft; Main sales corner At that time, lateral force Equivalent force arm for the main pin shaft; Main sales corner At that time, vertical force Equivalent force arm for the kingpin.

[0054] S4: Based on the wheel-end driving torque, wheel-end braking torque, and wheel angular acceleration, estimate the tire longitudinal force using a wheel rotation dynamics model; based on the vehicle mass, center of gravity height, distance from the center of gravity to the front and rear axles, track width between the front and rear axles, lateral load transfer ratio between the front and rear axles, and the vehicle's longitudinal and lateral accelerations, estimate the tire vertical force using a load transfer model. The longitudinal force of the tire is the product of the wheel-end driving torque, the wheel-end braking torque, the equivalent moment of inertia of the wheel, and the wheel angular acceleration, divided by the effective rolling radius of the tire. Specifically:

[0055] in, For the wheel end driving torque, For braking torque, The equivalent rotational inertia of the wheel, The angular velocity of the wheel. For the wheel angular acceleration, This is the effective rolling radius of the tire.

[0056] In some implementations, wheel angular acceleration It is obtained by differential and filtered differentiation of the wheel angular velocity signal, with a sampling period of 1. , No. k The wheel angular velocity at each sampling time is The wheel angular acceleration can be approximated as:

[0057] To suppress wheel speed sensor noise and differential amplification noise, a first-order low-pass filter is used in practical applications to obtain smoothed angular acceleration values:

[0058] in, This is the filtered wheel angular acceleration. These are the filter coefficients, and .

[0059] The load transfer model includes static wheel load calculation, longitudinal load transfer calculation, and lateral load transfer calculation. Specifically, it calculates the static wheel load when the vehicle is stationary or traveling at a constant speed in a straight line, and neglects the effects of aerodynamics and road slope. The static loads of the front axle and rear axle are as follows:

[0060] in, For front axle static load, For the rear axle static load, For the overall vehicle quality, It is the acceleration due to gravity. This is the distance from the vehicle's center of gravity to the rear axle. This is the distance from the vehicle's center of gravity to the front axle. This refers to the vehicle's wheelbase.

[0061] In some implementations, the static tire vertical forces of the left front wheel, right front wheel, left rear wheel, and right rear wheel are expressed as:

[0062] Among them, subscript , , , These represent the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0063] Calculate the load transfer caused by longitudinal acceleration and deceleration. When the vehicle accelerates forward, the inertial moment reduces the front axle load and increases the rear axle load; when the vehicle accelerates... The value is positive when the vehicle brakes. It is negative; the longitudinal load transfer of the whole vehicle is:

[0064] in, It represents the height of the center of mass.

[0065] If the longitudinal load transfer is evenly distributed to the left and right wheels on the same axle, the changes in vertical force on each front wheel and each rear wheel are as follows:

[0066] in, This represents the change in vertical force on the left front tire. This represents the change in vertical force on the right front tire. This represents the change in vertical force on the left rear tire. This represents the change in vertical force on the right rear tire.

[0067] Calculate the load transfer caused by lateral acceleration. When a vehicle experiences lateral acceleration, the height of the vehicle's center of gravity creates a vertical load difference between the inner and outer wheels. If the front and rear suspension roll stiffness distribution is known, determine the lateral load transfer ratios for the front and rear axles based on the actual roll stiffness distribution. Let the front axle lateral load transfer ratio be... The rear axle lateral load transfer ratio is ,satisfy:

[0068] The lateral load transfer amount of each wheel on the front and rear axles is:

[0069] in, Represents the front axle track. This represents the rear axle track width.

[0070] In some implementations, the estimated vertical tire forces of the four wheels are obtained by combining static wheel load, longitudinal load transfer, and lateral load transfer.

[0071] in, , , and These represent the vertical loads on the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0072] S5: Substitute the kingpin disturbance torque, tire longitudinal force, and tire vertical force into the torque projection relationship, introduce the tire return torque to correct the lateral force equivalent arm coefficient, back-calculate the tire lateral force of each wheel to be estimated, output the tire longitudinal force, tire lateral force, and tire vertical force of each wheel to be estimated, and output the adhesion utilization rate of each wheel to the vehicle control system.

[0073] In some implementations, the master pin space geometric mapping relationship obtained in step S3 is written as:

[0074] in, Subscript , , , These represent the front left wheel, front right wheel, rear left wheel, and rear right wheel, respectively. This represents the kingpin disturbance torque caused by tire force on the corresponding wheel. , , The forces corresponding to the tire contact points along the x, y, and z axes of the vehicle body coordinate system; , , These are the equivalent force arm coefficients of the longitudinal force, lateral force, and vertical force on the main pin shaft, respectively.

[0075] In some implementations, the longitudinal and vertical forces are substituted into the moment projection relationship to calculate the lateral force:

[0076] It should be noted that when a vehicle turns, the tires have a side slip angle, and the rubber within the tire contact patch undergoes lateral deformation, resulting in lateral force. The equivalent point of action is usually not at the selected tire contact point, but rather offset relative to the contact point; this offset is called aerodynamic trail. This will generate a restoring torque. :

[0077] at this time, ; in, Let be the projection coefficient of the tire return torque in the direction of the kingpin shaft; Introducing the tire return torque into the torque projection relationship, we obtain:

[0078] Introducing the tire self-aligning torque to correct the lateral force equivalent lever coefficient is:

[0079] Lateral force calculation updated as follows:

[0080] in, This is the projection coefficient of the tire return torque in the direction of the kingpin shaft; , and These are the longitudinal force, lateral force, and vertical force of the tire corresponding to the wheel; , and These are the equivalent force arm coefficients of the longitudinal force, lateral force, and vertical force on the main pin, respectively. The equivalent force arm coefficient of the lateral force after introducing the tire self-aligning torque; This represents the total disturbance torque generated around the main pin axis.

[0081] Based on tire adhesion constraints, the estimated lateral forces are subject to reasonable limitations. The resultant force in the tire plane should satisfy the adhesion limit constraints.

[0082] in, The available coefficient of adhesion for the corresponding road surface where the wheels are located is obtained from the vehicle road surface adhesion identification results, and the upper limit of the allowable lateral force of the tire is calculated accordingly. :

[0083] In some implementations, if the calculated lateral force exceeds the upper limit, a saturation function is used for constraint.

[0084] In step S5, the available adhesion coefficient of the road surface where the wheel to be estimated is located is obtained. The adhesion limit constraint is set so that the resultant force of the tire longitudinal force and the tire lateral force is no greater than the product of the available adhesion coefficient and the tire vertical force. The calculated tire lateral force is then limited. The adhesion utilization rate is calculated according to the following formula:

[0085] in, To improve the utilization rate of the adhesive, The available adhesion coefficient; when the adhesion utilization rate reaches a preset threshold, the corresponding wheel is determined to be close to the adhesion limit.

[0086] In some implementations, when the adhesion utilization rate reaches or exceeds a preset threshold When the wheel is close to its adhesion limit, it is determined that the corresponding wheel is approaching its limit. The preset threshold is calibrated according to the vehicle stability control requirements, and the preferred value range is 0.8 to 0.9.

[0087] When satisfied If the combined longitudinal and lateral forces of the corresponding wheel have already consumed a significant proportion of the road surface adhesion capacity, the wheel is at risk of approaching slippage, sideslip, or adhesion saturation. In this case, the estimated tire force and adhesion status judgment of the corresponding wheel are sent to the vehicle stability control, trajectory tracking control, anti-skid control, yaw moment control, or fault-tolerant control system.

[0088] In some implementations, to facilitate invocation by the vehicle control system, the present invention organizes the estimation results of each wheel into a single-wheel tire force and adhesion state output vector:

[0089] in, This is the output vector for the tire force and adhesion state of the corresponding wheel.

[0090] In another embodiment, this invention proposes a tire force estimation system for corner module vehicles based on a kingpin steering motor, implementing the tire force estimation method for corner module vehicles based on a kingpin steering motor as described above, including: The signal acquisition and processing module is used to acquire vehicle status signals of each wheel to be estimated, including kingpin steering motor current, kingpin angle, kingpin angular velocity, wheel angular velocity, wheel-end drive torque and wheel-end braking torque, as well as vehicle longitudinal acceleration and lateral acceleration. It performs time synchronization and filtering on the vehicle status signals and obtains kingpin angular acceleration and wheel angular acceleration. The kingpin torque conversion and dynamic compensation module is used to convert the kingpin steering motor current, combined with the preset motor torque constant, reducer transmission ratio and transmission efficiency, into the equivalent output torque of the kingpin shaft; it calculates the inertial torque and damping torque based on the kingpin angular acceleration and kingpin angular velocity, as well as the equivalent friction torque generated by the mechanical friction inside the kingpin steering system, and subtracts it from the equivalent output torque to obtain the kingpin disturbance torque caused by the tire force; The kingpin spatial geometry mapping module is used to obtain the unit vector of the kingpin axis direction and the position vector of the tire contact point relative to the reference point on the kingpin axis under the current kingpin rotation angle. The position vector is cross-multiplied with the longitudinal, lateral and vertical unit vectors respectively and projected onto the kingpin axis direction to obtain the equivalent force arm coefficients of the longitudinal force, lateral force and vertical force, and to establish the moment projection relationship between the kingpin disturbance torque and each tire force component. The longitudinal and vertical force estimation modules are used to estimate the tire longitudinal force based on the wheel-end driving torque, wheel-end braking torque, and wheel angular acceleration using a wheel rotation dynamics model; and to estimate the tire vertical force based on the vehicle mass, center of gravity height, distance from the center of gravity to the front and rear axles, track width between the front and rear axles, lateral load transfer ratio between the front and rear axles, and the vehicle's longitudinal and lateral accelerations using a load transfer model. The lateral force back-calculation and adhesion status output module is used to substitute the kingpin disturbance torque, tire longitudinal force and tire vertical force into the torque projection relationship, introduce the tire return torque to correct the lateral force equivalent arm coefficient, back-calculate the tire lateral force of each wheel to be estimated, output the tire longitudinal force, tire lateral force and tire vertical force of each wheel to be estimated, and calculate the adhesion utilization rate of each wheel before outputting it to the vehicle control system.

[0091] In another embodiment of the present invention, an electronic device is proposed, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements a method for estimating the tire force of a vehicle based on a kingpin steering motor as described above.

[0092] In another embodiment of the present invention, a computer-readable storage medium is provided storing a computer program that causes a computer to execute a method for estimating tire forces of a vehicle based on a kingpin steering motor, as described above.

[0093] In the embodiments disclosed in this application, a computer storage medium may be a tangible medium that may contain or store programs for use by or in conjunction with an instruction execution system, apparatus, or device. The computer storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of computer storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for estimating tire force in a vehicle based on a kingpin steering motor, characterized in that, Includes the following steps: S1: Collect vehicle status signals for each wheel to be estimated, including kingpin steering motor current, kingpin angle, kingpin angular velocity, wheel angular velocity, wheel-end drive torque and wheel-end braking torque, as well as vehicle longitudinal acceleration and lateral acceleration. Perform time synchronization and filtering on the vehicle status signals, and obtain kingpin angular acceleration and wheel angular acceleration. S2: Calculate the equivalent output torque of the kingpin shaft based on the kingpin steering motor current, combined with the preset motor torque constant, reducer transmission ratio and transmission efficiency; calculate the inertial torque and damping torque based on the kingpin angular acceleration and kingpin angular velocity, as well as the equivalent friction torque generated by the internal mechanical friction of the kingpin steering system, and subtract it from the equivalent output torque to obtain the kingpin disturbance torque caused by the tire force; S3: Under the current kingpin rotation angle, obtain the unit vector in the kingpin shaft direction and the position vector of the tire contact point relative to the reference point on the kingpin shaft. After cross-multiplying the position vector with the longitudinal, lateral and vertical unit vectors respectively, project it onto the kingpin shaft direction to obtain the equivalent force arm coefficients of the longitudinal force, lateral force and vertical force, and establish the moment projection relationship between the kingpin disturbance torque and each tire force component. S4: Based on the wheel-end driving torque, wheel-end braking torque, and wheel angular acceleration, estimate the tire longitudinal force using a wheel rotation dynamics model; based on the vehicle mass, center of gravity height, distance from the center of gravity to the front and rear axles, track width between the front and rear axles, lateral load transfer ratio between the front and rear axles, and the vehicle's longitudinal and lateral accelerations, estimate the tire vertical force using a load transfer model. S5: Substitute the kingpin disturbance torque, tire longitudinal force, and tire vertical force into the torque projection relationship, introduce the tire return torque to correct the lateral force equivalent arm coefficient, back-calculate the tire lateral force of each wheel to be estimated, output the tire longitudinal force, tire lateral force, and tire vertical force of each wheel to be estimated, and output the adhesion utilization rate of each wheel to the vehicle control system.

2. The method for estimating vehicle tire force based on a kingpin steering motor according to claim 1, characterized in that: In step S1, the kingpin steering motor is a permanent magnet synchronous motor, and the kingpin steering motor current is the q-axis current obtained by coordinate transformation of the motor phase current; the kingpin rotational velocity is obtained directly by the rotational angle sensor or by differentially analyzing the kingpin rotational angle, and the kingpin rotational acceleration and wheel angular acceleration are obtained by differentially analyzing the kingpin rotational velocity and wheel angular velocity and then by low-pass filtering.

3. The method for estimating vehicle tire force based on a kingpin steering motor according to claim 1, characterized in that: In step S2, the equivalent output torque of the main pin shaft and the disturbance torque of the main pin are respectively expressed as: in, The equivalent output torque of the main pin shaft For transmission efficiency, The gear ratio of the reducer. The torque constant of the motor. The current of the master steering motor. Main pin disturbance torque The equivalent rotational inertia of the masterpipe steering system Main pin rotational speed, Main pin rotational acceleration This is the equivalent damping coefficient. The equivalent frictional torque is obtained through calibration or friction modeling, and its sign varies with the direction of kingpin rotation.

4. The method for estimating vehicle tire force based on a kingpin steering motor according to claim 1, characterized in that: In step S3, the vehicle's forward direction, left side direction, and top direction are used as the x-axis, y-axis, and z-axis of the vehicle coordinate system, respectively. A point on the kingpin axis is selected as a reference point; the unit vector of the kingpin axis direction is represented as... The position vector is represented as And the equivalent arm coefficient is expressed as: in, , and These represent the unit components of the kingpin axis in the longitudinal, lateral, and vertical directions of the vehicle, respectively. , and These represent the components of the position vector in the longitudinal, lateral, and vertical directions of the vehicle, respectively. Main sales corner At that time, longitudinal force Equivalent force arm for the main pin shaft; Main sales corner At that time, lateral force Equivalent force arm for the main pin shaft; Main sales corner At that time, vertical force Equivalent force arm for the kingpin.

5. The method for estimating vehicle tire force based on a kingpin steering motor according to claim 1, characterized in that: In step S4, the longitudinal force of the tire is the value obtained by subtracting the braking torque at the wheel end and the product of the wheel's equivalent moment of inertia and the wheel's angular acceleration from the wheel-end driving torque, and then dividing by the effective rolling radius of the tire; the load transfer model includes static wheel load calculation, longitudinal load transfer calculation, and lateral load transfer calculation. The static loads on the front and rear axles are calculated using the vehicle's mass, gravitational acceleration, distance from the center of gravity to the front and rear axles, and wheelbase, and the static loads on each axle are evenly distributed to the left and right wheels. The longitudinal load transfer between the front and rear axles is calculated using the vehicle's mass, center of gravity height, wheelbase, and longitudinal acceleration. The lateral load transfer between the left and right wheels on each axle is calculated using the vehicle's mass, center of gravity height, front and rear axle track width, lateral acceleration, and the lateral load transfer ratio between the front and rear axles. The static wheel loads, longitudinal load transfers, and lateral load transfers are superimposed to obtain the vertical tire force of each wheel. The lateral load transfer ratio between the front and rear axles is obtained from the front and rear suspension roll stiffness distribution relationship or calibration results, and the sum of the two is 1.

6. The method for estimating vehicle tire force based on a kingpin steering motor according to claim 1, characterized in that: In step S5, the introduction of the tire return torque to correct the lateral force equivalent lever coefficient includes: pneumatic tire trail The tire self-aligning torque is expressed as the offset distance between the point of application of the lateral force on the tire and the point of contact with the ground. Introducing the tire return torque into the torque projection relationship, we obtain: in, This is the projection coefficient of the tire return torque in the direction of the kingpin shaft; , and These are the longitudinal force, lateral force, and vertical force of the tire corresponding to the wheel; , and These are the equivalent force arm coefficients of the longitudinal force, lateral force, and vertical force on the main pin, respectively. The equivalent force arm coefficient of the lateral force after introducing the tire self-aligning torque; This represents the total disturbance torque generated around the main pin axis.

7. The method for estimating tire force of a vehicle based on a kingpin steering motor according to claim 6, characterized in that: In step S5, the available adhesion coefficient of the road surface where the wheel to be estimated is located is obtained. The adhesion limit constraint is set so that the resultant force of the tire longitudinal force and the tire lateral force is no greater than the product of the available adhesion coefficient and the tire vertical force. The calculated tire lateral force is then limited. The adhesion utilization rate is calculated according to the following formula: in, To improve the utilization rate of the adhesive, The available adhesion coefficient; when the adhesion utilization rate reaches a preset threshold, the corresponding wheel is determined to be close to the adhesion limit.

8. A tire force estimation system for a corner module vehicle based on a kingpin steering motor, used to implement the tire force estimation method for a corner module vehicle based on a kingpin steering motor as described in any one of claims 1 to 7, characterized in that, include: The signal acquisition and processing module is used to acquire vehicle status signals of each wheel to be estimated, including kingpin steering motor current, kingpin angle, kingpin angular velocity, wheel angular velocity, wheel-end drive torque and wheel-end braking torque, as well as vehicle longitudinal acceleration and lateral acceleration. It performs time synchronization and filtering on the vehicle status signals and obtains kingpin angular acceleration and wheel angular acceleration. The kingpin torque conversion and dynamic compensation module is used to convert the kingpin steering motor current, combined with the preset motor torque constant, reducer transmission ratio and transmission efficiency, into the equivalent output torque of the kingpin shaft; it calculates the inertial torque and damping torque based on the kingpin angular acceleration and kingpin angular velocity, as well as the equivalent friction torque generated by the mechanical friction inside the kingpin steering system, and subtracts it from the equivalent output torque to obtain the kingpin disturbance torque caused by the tire force; The kingpin spatial geometry mapping module is used to obtain the unit vector of the kingpin axis direction and the position vector of the tire contact point relative to the reference point on the kingpin axis under the current kingpin rotation angle. The position vector is cross-multiplied with the longitudinal, lateral and vertical unit vectors respectively and projected onto the kingpin axis direction to obtain the equivalent force arm coefficients of the longitudinal force, lateral force and vertical force, and to establish the moment projection relationship between the kingpin disturbance torque and each tire force component. The longitudinal and vertical force estimation modules are used to estimate the tire longitudinal force based on the wheel-end driving torque, wheel-end braking torque, and wheel angular acceleration using a wheel rotation dynamics model; and to estimate the tire vertical force based on the vehicle mass, center of gravity height, distance from the center of gravity to the front and rear axles, track width between the front and rear axles, lateral load transfer ratio between the front and rear axles, and the vehicle's longitudinal and lateral accelerations using a load transfer model. The lateral force back-calculation and adhesion status output module is used to substitute the kingpin disturbance torque, tire longitudinal force and tire vertical force into the torque projection relationship, introduce the tire return torque to correct the lateral force equivalent arm coefficient, back-calculate the tire lateral force of each wheel to be estimated, output the tire longitudinal force, tire lateral force and tire vertical force of each wheel to be estimated, and calculate the adhesion utilization rate of each wheel before outputting it to the vehicle control system.

9. An electronic device, characterized in that, include: The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements a method for estimating tire force of a vehicle based on a kingpin steering motor as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The computer program causes the computer to execute a method for estimating tire force of a vehicle based on a kingpin steering motor, as described in any one of claims 1 to 7.

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