Method, device and equipment for determining rack force of vehicle, vehicle and storage medium

Abstract

The invention provides a method and device for determining vehicle rack force and related equipment. On one hand, the stress conditions of two steering wheels on a steering shaft are firstly obtained, then the master pin total torque of the steering shaft is determined on the basis of the stress conditions of the steering wheels in combination with master pin parameters of the steering shaft, and the first rack force of the steering shaft is determined from the mechanical angle according to the master pin total torque; on the other hand, the second rack force of the steering shaft can be determined from the angle of kinematics according to the motion data of the target vehicle; on the other hand, the third rack force of the steering shaft can be determined from the angle for driving the steering shaft according to the output condition of the steering motor of the steering shaft. That is to say, when the rack force of the steering shaft is estimated, three times of rack force estimation can be carried out from three angles of kingpin stress, kinematics and a driving motor, and then the actual rack force is determined by integrating the rack force estimated for three times based on the actual situation of the vehicle. Thus, the rack force is determined by integrating multiple aspects, and the accuracy of the rack force can be improved.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and more particularly to a method, apparatus, device, vehicle, and storage medium for determining the rack force of a vehicle. Background Technology

[0002] The steer-by-wire system of a vehicle is divided into front-wheel steer-by-wire and rear-wheel steer-by-wire systems. It mainly consists of a steering power unit, a motor reduction mechanism, and moving parts such as tie rods and wheel linkages. Through the vehicle steer-by-wire system, the driver or the autonomous driving system can change the direction of the vehicle.

[0003] In a vehicle's steer-by-wire system, because there is no mechanical connection between the upper steering system (where the steering wheel is located) and the lower steering system (where the wheels are located), the torque of the lower steering cannot be directly transmitted to the upper steering system. However, in some application scenarios, the driver needs to feel the forces acting on the lower steering system to better control the steering wheel. Therefore, the rack force of the entire vehicle's steer-by-wire system can be estimated, and the feedback torque of the steering wheel can be determined based on the estimated rack force.

[0004] The accuracy of the estimated rack force is crucial for key performance aspects such as response precision, execution safety, and the realism of road feel simulation. Therefore, accurate estimation of the rack force is necessary. Summary of the Invention

[0005] In view of this, this application provides a method, apparatus, device, vehicle, and storage medium for determining the rack force of a vehicle, with the aim of accurately estimating the rack force of the vehicle's steer-by-wire system.

[0006] In a first aspect, this application provides a method for determining the rack force of a vehicle, the method comprising:

[0007] Obtain the force conditions of two steering wheels, which correspond to the same steering axle of the target vehicle;

[0008] Based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft, the total kingpin torque of the steering shaft is determined.

[0009] Based on the total kingpin torque, determine the first rack force of the steering shaft;

[0010] Based on the motion data of the target vehicle, the second rack force of the steering shaft is determined;

[0011] Based on the output of the steering motor of the steering shaft, the third rack force of the steering shaft is determined;

[0012] Based on the driving conditions of the target vehicle, the actual rack force of the steering shaft is determined by combining the first rack force, the second rack force, and the third rack force.

[0013] In some possible implementations, determining the total kingpin torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft includes:

[0014] Based on the force conditions of the two steering wheels and the kingpin parameters of the steering shaft, the gravity return torque, lateral kingpin torque, longitudinal kingpin torque and kingpin return torque of each steering wheel are determined respectively.

[0015] Based on the gravity return torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel, the total kingpin torque of each steering wheel is determined, and the total kingpin torque of the steering shaft is calculated.

[0016] In some possible implementations, determining the gravity-correcting torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft includes:

[0017] Obtain the rotation angle of the steering wheel;

[0018] Based on the supporting force of the steering wheel, the steering wheel's rotation angle, the kingpin offset distance of the steering wheel, and the kingpin inclination angle of the steering wheel, combined with the geometric relationship between the steering wheel and the kingpin, the gravity-correcting torque of the steering wheel is calculated.

[0019] The force conditions of the steering wheels are used to describe the supporting force of each steering wheel on the steering shaft; the kingpin parameters of the steering shaft include the kingpin offset and kingpin inclination angle.

[0020] In some possible implementations, the kingpin parameters of the steering shaft include the kingpin caster angle and kingpin inclination angle of the steering wheel, and the force conditions of the steering wheel include the steering wheel being subjected to a vertical rotational torque;

[0021] The kingpin return torque is obtained by the following method:

[0022] The relationship between the vertical rotational torque and the spindle return torque is determined based on the kingpin back tilt angle and the kingpin inclination angle.

[0023] Based on the aforementioned correlation, the spindle return torque is determined in conjunction with the vertical rotational torque.

[0024] In some possible implementations, determining the third rack force of the steering shaft based on the output of the steering motor of the steering shaft includes:

[0025] Monitor the conversion coefficient and output torque of the steering motor;

[0026] The third rack force is determined based on the preset motor resistance torque and rack resistance;

[0027] The motor resistance torque is determined based on the motor inertial torque, motor damping torque, and motor friction torque of the steering motor, while the rack resistance is determined based on the rack inertial force, rack damping force, and rack friction force of the steering shaft.

[0028] In some possible implementations, determining the actual rack force of the steering shaft based on the driving conditions of the target vehicle, in combination with the first rack force, the second rack force, and the third rack force, includes:

[0029] Based on the driving conditions of the target vehicle, validity information is determined. The validity information includes validity information corresponding to the first rack force, validity information corresponding to the second rack force, and validity information corresponding to the third rack force. The validity information indicates the reliability of the input signal used to calculate the rack force.

[0030] Based on the validity information, the calculation weights of the first rack force, the second rack force, and the third rack force are determined respectively, and the actual rack force of the steering shaft is calculated.

[0031] Secondly, this application provides a device for determining the rack force of a vehicle, the device comprising:

[0032] The acquisition unit is used to acquire the force conditions of two steering wheels, which correspond to the same steering axle of the target vehicle;

[0033] The first calculation unit is used to determine the total kingpin torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft; and to determine the first rack force of the steering shaft based on the total kingpin torque.

[0034] The second calculation unit is used to determine the second rack force of the steering shaft based on the motion data of the target vehicle;

[0035] The third calculation unit is used to determine the third rack force of the steering shaft based on the output of the steering motor of the steering shaft;

[0036] An estimation unit is used to determine the actual rack force of the steering shaft based on the driving conditions of the target vehicle, combined with the first rack force, the second rack force, and the third rack force.

[0037] In some possible implementations, the first calculation unit is specifically used to determine the gravity-aligning torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel based on the force conditions of the two steering wheels and in conjunction with the kingpin parameters of the steering shaft; and to determine the total kingpin torque of each steering wheel based on the gravity-aligning torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel, and to calculate the total kingpin torque of the steering shaft.

[0038] In some possible implementations, the force conditions of the steering wheel are considered in conjunction with the kingpin parameters of the steering shaft; the acquisition unit is further configured to acquire the steering wheel's rotation angle; the first calculation unit is specifically configured to calculate the gravity-correcting torque of the steering wheel based on the steering wheel's support force, the steering wheel's rotation angle, the steering wheel's kingpin offset, and the steering wheel's kingpin inclination angle, combined with the geometric relationship between the steering wheel and the kingpin; the force conditions of the steering wheel are used to describe the support force of each steering wheel on the steering shaft; the kingpin parameters of the steering shaft include the steering shaft's kingpin offset and kingpin inclination angle.

[0039] In some possible implementations, the kingpin parameters of the steering shaft include the kingpin caster angle and kingpin inclination angle of the steering wheel, and the force conditions of the steering wheel include the steering wheel being subjected to a vertical rotational torque; the first calculation unit is specifically used to determine the correlation between the vertical rotational torque and the main shaft return torque based on the kingpin caster angle and the kingpin inclination angle; and to determine the main shaft return torque based on the correlation and the vertical rotational torque.

[0040] In some possible implementations, the third calculation unit is specifically used to monitor the conversion coefficient and output torque of the steering motor; and to determine the third rack force based on preset motor resistance torque and rack resistance; wherein the motor resistance torque is determined based on the motor inertial torque, motor damping torque and motor friction torque of the steering motor, and the rack resistance is determined based on the rack inertial force, rack damping force and rack friction force of the steering shaft.

[0041] In some possible implementations, the estimation unit is specifically used to determine validity information based on the driving conditions of the target vehicle. The validity information includes validity information corresponding to the first rack force, the second rack force, and the third rack force. The validity information indicates the reliability of the input signal used to calculate the rack force. Based on the validity information, the unit determines the calculation weights of the first rack force, the second rack force, and the third rack force, respectively, and calculates the actual rack force of the steering shaft.

[0042] Thirdly, this application provides a control device, the control device including a memory and a processor, the memory being used to store instructions or code, and the processor being used to execute the instructions or code stored in the memory to implement the method as described in any one of the preceding first aspects.

[0043] Fourthly, this application provides a vehicle including a plurality of wheels and control devices as described in the fourth aspect.

[0044] Fifthly, this application provides a computer storage medium storing code, wherein when the code is executed, a device executing the code implements the method described in any of the first aspects above.

[0045] In a sixth aspect, a computer program product containing instructions is provided that, when run on a computer, causes the computer to perform the method described in any of the first aspects.

[0046] This application provides a method, apparatus, device, vehicle, and storage medium for determining the rack force of a vehicle. If it is necessary to estimate the rack force of a certain steering shaft of a target vehicle, firstly, the force conditions of the two steering wheels on the steering shaft are obtained. Then, based on the force conditions of the steering wheels and the kingpin parameters of the steering shaft, the total kingpin torque of the steering shaft is determined, and the first rack force of the steering shaft is determined from a mechanical perspective based on the total kingpin torque. Secondly, the second rack force of the steering shaft can be determined from a kinematic perspective based on the motion data of the target vehicle. Thirdly, the third rack force of the steering shaft can be determined from the perspective of driving the steering shaft based on the output of the steering motor of the steering shaft. Finally, the actual rack force of the steering shaft can be determined based on the actual driving conditions of the target vehicle, combining the first, second, and third rack forces. In other words, when estimating the rack force of the steering shaft, the rack force can be estimated three times from three perspectives: kingpin force, vehicle kinematics, and drive motor. Then, based on the actual vehicle conditions, the rack force is determined by combining the three estimated rack forces. In this way, by estimating the rack force from multiple aspects, the magnitude of the rack force can be comprehensively determined. By considering the actual driving conditions of the vehicle, the accuracy of rack force estimation can be improved. Therefore, determining the rack force by integrating multiple factors can further enhance its accuracy. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings used in the description of the embodiment or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 A flowchart illustrating a method for determining vehicle rack force according to an embodiment of this application;

[0049] Figure 2 This is a schematic diagram of a vehicle rack force determination device provided in an embodiment of this application. Detailed Implementation

[0050] For vehicles equipped with a steer-by-wire system, rack force estimation is a crucial aspect of vehicle control. The accuracy of the estimated rack force is closely related to steering accuracy, safety, and the realism of road feel simulation. In particular, in vehicles equipped with driver assistance, intelligent driving, and autonomous driving systems, it is even more necessary to determine steering wheel feedback through rack force to allow the user to understand the vehicle's driving status.

[0051] Therefore, to improve driving safety and experience, accurate estimation of rack force is necessary. Currently, some implementations estimate rack force based on the output of the steering motor, which drives the steering shaft. Based on the steering motor's output, the driving force on the steering shaft can be determined, thus determining the rack force. In other implementations, kinematic analysis of the vehicle can be performed, using data such as yaw acceleration and angular acceleration to determine the rack force.

[0052] However, both the methods for determining rack force based on the steering motor output and those based on kinematic analysis have certain limitations. Specifically, for the method based on the steering motor output, the rack force determined under conditions such as rough roads may contain errors; furthermore, wear and aging of the steering system can affect the transmission of torque output from the steering motor, also leading to errors in the estimated rack force. For the method based on kinematic analysis, road surface disturbances, such as bumps, may cause errors in the kinematic parameters collected by the sensors, resulting in errors in the rack force.

[0053] To address the aforementioned issues, some implementations combine dynamic analysis with the output of the steering motor to determine the rack force. This can improve the accuracy of the estimated rack force to some extent; however, the parameters used to estimate the rack force are not directly related to the rack force itself, and some error still exists. Furthermore, this estimation method relies on the accuracy of the sensor signals, resulting in poor robustness.

[0054] In view of this, embodiments of this application provide a method for determining the rack force of a vehicle. This method can be applied to a vehicle controller, such as the vehicle's overall controller or the steering control unit in a vehicle steer-by-wire system. If the vehicle has rear-wheel steering, then this method can be applied to the control unit in the vehicle steer-by-wire system used to control the rear-wheel steering to determine the rack force of the vehicle's rear steering axle.

[0055] The method for determining vehicle rack force provided in this application embodiment will be described below from the perspective of a vehicle rack force determining device. The vehicle rack force determining device is a software module used to determine the rack force of a specific steering axle of a vehicle. It can run in the steering control unit of the aforementioned vehicle controller or vehicle steer-by-wire system. The method for determining vehicle rack force provided in this application embodiment can be applied to vehicles with one steering axle or vehicles with multiple steering axles. For ease of explanation, the following description will take determining the rack force of a target steering axle in a target vehicle as an example. The target steering axle can be either the front or rear steering axle of the target vehicle.

[0056] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0057] See Figure 1 , Figure 1 A flowchart of a method for determining vehicle rack force provided in this application embodiment includes:

[0058] S101: Obtain the force conditions of the two steering wheels.

[0059] In this embodiment, the rack force of the steering shaft can be determined by considering the actual force applied to the steering shaft. To determine the actual force applied to the steering shaft, the force applied to the two steering wheels on the steering shaft can first be obtained. For example, if the rack force to be determined is the rack force of the front steering shaft, the force applied to the left front wheel and the right front wheel of the target vehicle can be obtained separately; if the rack force to be determined is the rack force of the rear steering shaft, the force applied to the left rear wheel and the right rear wheel of the target vehicle can be obtained separately.

[0060] In the embodiments of this application, the force situation of the steering wheel can include the magnitude of the six component forces of the steering wheel. The six component forces refer to the forces that the tire experiences in the three coordinate axes based on a three-dimensional Cartesian coordinate system established by the tire, as well as the torques that the tire experiences when rotating along the three coordinate axes.

[0061] For ease of explanation, the following text will use the aforementioned "three-dimensional rectangular coordinate system based on tires" as an example, with the x-axis pointing in the opposite direction of vehicle movement and the z-axis pointing vertically upwards. Correspondingly, the forces received by the steering wheel in the three directions can be expressed as F... X F Y and F z .

[0062] S102: Based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft, determine the total kingpin torque of the steering shaft.

[0063] After obtaining the force conditions on the steering wheels, the total kingpin torque of the steering shaft can be determined by combining the kingpin parameters of the steering wheels. The kingpin parameters of the steering shaft refer to the kingpin positioning parameters of the suspension corresponding to the steering shaft, indicating the relationship between each steering wheel and the kingpin. The total kingpin torque refers to the total torque generated by the steering wheel at its kingpin. The total kingpin torque of the steering shaft represents the total torque generated by the steering shaft pushing the kingpin. In the vehicle's transmission system, the steering shaft is subjected to rack force, which, under the action of the rack force, pushes the steering wheels to rotate around the kingpin. Therefore, the total kingpin torque output from the steering shaft can be used to deduce the rack force input to the steering shaft.

[0064] Optionally, for a steering axle connecting the left and right wheels, the total kingpin torque of the left wheel and the total kingpin torque of the right wheel can be calculated separately, and then summed to obtain the total kingpin torque of the steering axle. The following uses a single wheel as an example to introduce some methods for determining the total kingpin torque of a single wheel.

[0065] Specifically, the gravity-aligning torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel can be calculated separately, and then the total kingpin torque of the steering wheel can be determined based on the correlation. The correlation represents the relationship between the gravity-aligning torque, lateral kingpin torque, longitudinal kingpin torque, kingpin return torque, and total kingpin torque.

[0066] Understandably, in physics, torque is a vector with direction, and correlations can indicate the directional relationship between individual torques. By vector summing the individual torques based on these correlations, the total kingpin torque can be obtained. Alternatively, in some other possible implementations, each torque can be projected onto the direction of the total kingpin torque when calculating individual torques, and then treated as a scalar. Thus, when calculating the total kingpin torque of the steering wheel, the gravity-induced self-aligning torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of the steering wheel can be summed to obtain the total kingpin torque of the steering wheel.

[0067] The following sections introduce some methods for calculating various torques.

[0068] The gravity-based self-aligning moment of a steering wheel refers to the torque generated by the gravity acting on the steering wheel, causing it to rotate around the kingpin. When calculating the gravity-based self-aligning moment, one can calculate the distance from the steering wheel's center of gravity to the kingpin and its projected length in a plane perpendicular to the kingpin; another can calculate the tangential component of the gravity acting on the steering wheel. This tangential component lies in the aforementioned plane perpendicular to the kingpin, and its direction is tangential to the rotational trajectory of the steering wheel's center of gravity.

[0069] Specifically, the force F acting on the wheel in the vertically upward direction can be obtained through step S101. z and F z As the weight of the wheel, the kingpin parameters of the steering axle include the kingpin offset d at the center of the steering wheel. z and kingpin inclination angle δ kp The steering angle δ of the steering wheel can be obtained through the steering sensor.

[0070] Thus, the distance from the center of gravity of the aforementioned steering wheel to the kingpin can be expressed as: d1 = d z *cos (δ kp The tangential component of the force mentioned above can be expressed as F1 = F z *sin (δ kp Then the gravity-correcting torque M of the steering wheel is )*cos (δ). z1 It can be obtained through the following formula (1).

[0071] Formula (1): M z1 =F z *sin(δ kp )*cos(δ)*d z *cos(δ kp )

[0072] =F z *d z *sin(2*δ kp sin(δ)

[0073] Lateral kingpin moment refers to the torque generated by the lateral force acting on the steering wheel, which causes the steering wheel to rotate about the kingpin. Longitudinal kingpin moment refers to the torque generated by the longitudinal force acting on the steering wheel, which causes the steering wheel to rotate about the kingpin. The lateral force refers to the force acting on the wheel along the line connecting the wheel centers and pointing outwards from the vehicle; for example, it could be the force F along the Y-axis of the coordinate system mentioned above. Y Longitudinal force refers to the force received by the wheel that points forward (or backward) along the vehicle's direction of travel. For example, it could be the force F along the Z-axis of the coordinate system mentioned above. Z Accordingly, the lateral kingpin moment and longitudinal kingpin moment of the steering wheel can be calculated using the following formulas (2) and (3), respectively.

[0074] Formula (2): M z2 =F Y *d x =F Y *R*tanδ caster

[0075] Formula (3): M z3 =F X *d y =F X *R*tanδ kp

[0076] Where, d x It is the offset distance of the master pin in the x-direction in the coordinate system, d y It is the offset distance in the x-direction of the coordinate system, R is the wheel radius, and δ caster Kingpin inclination angle indicates the angle at which the kingpin tilts backward.

[0077] The kingpin return torque is the torque generated by the force acting on the steering wheel that causes the steering wheel to rotate around the kingpin. Specifically, the kingpin return torque can be obtained from the torque acting on the steering wheel that causes it to rotate around the Z-axis. This torque acting on the steering wheel that causes it to rotate around the Z-axis can also be called the vertical rotational torque.

[0078] By analyzing the kingpin parameters and geometric relationships of the tire, the correlation between the kingpin return torque and the vertical rotational torque can be obtained. Based on this correlation, and combined with the actual vertical rotational torque experienced by the steering wheel, the kingpin return torque can be determined. Specifically, if a cube is constructed based on the kingpin return torque and the vertical rotational torque, and the height of the cube is 1, then the length and width of the cube are tan(δ... kp ) and tan(δ caster The kingpin return torque corresponds to the diagonal of the cube, and the vertical rotation torque corresponds to the height of the cube. This relationship represents the correspondence between the height of the cube and the length of its diagonal. Therefore, based on the above analysis, the kingpin return torque M can be calculated using the following formula (4). z4 .

[0079] Formula (4):

[0080] Among them, M z This is the vertical rotational torque.

[0081] The aforementioned gravity-aligning torque, lateral kingpin torque, kingpin return torque, and kingpin return torque are external torques on the steering wheel, other than the total kingpin torque, that cause the wheel to rotate around the kingpin. If the steering wheel does not rotate around the kingpin, then the steering wheel is in equilibrium in the direction of rotation around the kingpin. Therefore, it can be known that the total kingpin torque on the steering wheel is in balance with the gravity-aligning torque, lateral kingpin torque, kingpin return torque, and kingpin return torque. Therefore, the total kingpin torque M of the steering wheel can be calculated using the following formula (5). zkp .

[0082] Formula (5): M zkp =M z1 +M z2 +M z3 +M z4

[0083] Using formulas (1) to (5) above, the total kingpin torque M acting on a steering wheel on the steering shaft can be calculated. zkp Calculate the total kingpin torque M acting on the two steering wheels on the steering axle respectively. zkp The total kingpin torque M of the steering shaft can be obtained. zkp ′ .

[0084] S103: Determine the first rack force of the steering shaft based on the total kingpin torque.

[0085] After calculating the total kingpin torque of the steering shaft, the first rack force of the steering shaft can be determined based on the total kingpin torque. Specifically, the lever arm from the kingpin to the rack end can be obtained, and then the first rack force on the steering shaft can be calculated based on the lever arm from the kingpin to the rack end. Specifically, the first rack force F1 can be calculated using the following formula (6).

[0086] Formula (6):

[0087] Among them, M zkp ′ This refers to the total torque of the kingpin on the steering shaft, and Lever is the length of the lever arm from the kingpin to the rack end.

[0088] In this embodiment, the first rack force refers to the rack force calculated based on the force on the steering shaft. Since the parameters used to calculate the first rack force are the vehicle's own data (e.g., kingpin parameters) and the force on the steering wheel, the accuracy of the first rack force can be guaranteed as long as the vehicle as a whole is not damaged and the module used to obtain the six-part force of the steering wheel is not damaged.

[0089] S104: Determine the second rack force of the steering shaft based on the motion data of the target vehicle.

[0090] In this embodiment, in addition to calculating the rack force based on the force on the steering shaft, the rack force of the steering shaft can also be calculated based on the motion data of the target vehicle. Specifically, the motion data of the target vehicle refers to data related to the yaw motion of the target vehicle, which may include the lateral acceleration, yaw angle acceleration, and yaw radius of the target vehicle.

[0091] Specifically, the second rack force F2 can be calculated using the following formula (7).

[0092] Formula (7):

[0093] Where m is the axle load of the steering shaft. γ is the lateral acceleration of the steering shaft, γ is the yaw acceleration of the vehicle, and u is the yaw radius of the vehicle. Based on formula (7), the yaw motion of the vehicle can be modeled from the perspective of vehicle dynamics and the rack force that causes the vehicle to yaw can be solved.

[0094] S105: Determine the third rack force of the steering shaft based on the output of the steering motor of the steering shaft.

[0095] In addition to force analysis and kinematic analysis, to more accurately estimate the rack force acting on the steering shaft, the rack force can also be estimated based on the output of the steering motor corresponding to the steering shaft. Specifically, the output of the steering motor can be obtained through the vehicle bus, and the third rack force of the steering shaft can be obtained by combining the output torque of the steering motor and the torque conversion coefficient of the steering motor.

[0096] Specifically, the third rack force F3 can be calculated using the following formula (8).

[0097] Formula (8): F3 = i*(M o -T1-T2-T3)-(F r1 +F r2 +F r3 )

[0098] Where i is the conversion coefficient from the output torque of the steering motor to the rack force, and M o T1 is the output torque of the steering motor, T2 is the motor inertial torque, T3 is the motor damping torque, and F is the motor friction torque. r1 For the rack inertial force, F r2 For rack damping force, F r3 This refers to the frictional force of the rack and pinion.

[0099] Among them, the motor inertial torque, motor damping torque, and motor friction torque are resistance torques originating from within the steering motor; their sum can be referred to as the motor resistance torque. The rack inertial force, rack damping force, and rack friction force are resistance forces originating from the rack on the steering shaft, and can be referred to as rack resistance. In other words, when determining the third rack force, the resistance torque from the motor and the resistance force from the rack can be determined separately. First, based on the motor's output torque, motor resistance torque, and conversion coefficient, the actual output power of the steering motor is calculated. Then, based on the power and rack resistance, the final rack force output by the rack, i.e., the third rack force, is calculated.

[0100] By taking into account the resistance torque from the motor and the resistance from the rack, the accuracy of the third rack force can be improved, thereby improving the accuracy of the final estimated rack force.

[0101] S106: Determine the actual rack force of the steering shaft based on the driving conditions of the target vehicle, combined with the first rack force, the second rack force, and the third rack force.

[0102] Through steps S103-S105 above, the rack force of the steering shaft can be estimated from three perspectives: force analysis, vehicle kinematics, and motor output. It is understandable that in real-world scenarios, due to errors in the detection equipment and actual operating conditions, there may be some discrepancy between any one or more of the first, second, and third rack forces and the actual rack force acting on the steering shaft. Therefore, to accurately estimate the rack force of the steering shaft, the actual rack force can be determined based on the actual form of the target vehicle, combined with the first, second, and third rack forces.

[0103] Specifically, based on the target vehicle's driving conditions, the validity information corresponding to the first rack force, the second rack force, and the third rack force can be determined separately. The validity information indicates the reliability of the input signal used to calculate the corresponding rack force. For example, the validity information corresponding to the first rack force indicates the reliability of the vehicle's kingpin parameters and the six component forces of the steering wheel; the validity information corresponding to the second rack force indicates the reliability of the vehicle's kinematic parameters (including axle load, lateral acceleration, yaw rate, and yaw radius); and the validity information corresponding to the third rack force indicates the reliability of the output torque of the vehicle's steering motor.

[0104] For example, under low-speed conditions, the accuracy of the vehicle's kinematic parameters may be high, while the accuracy of the steering motor's output torque may be low due to the influence of drag and drag torque. Conversely, under high-speed conditions, the accuracy of the vehicle's kinematic parameters may be poor, while the accuracy of the steering motor's output torque may be high. Therefore, if the target vehicle's driving conditions indicate that it is traveling at low speed, the effectiveness of the second rack force can be appropriately increased, and the effectiveness of the third rack force can be correspondingly decreased; if the target vehicle's driving conditions indicate that it is traveling at high speed, the effectiveness of the second rack force can be appropriately decreased, and the effectiveness of the third rack force can be correspondingly increased.

[0105] For example, when the target vehicle enters a degraded state or a fault protection state, the confidence levels of the second and third rack forces will decrease. Therefore, the effectiveness of the first rack force can be increased, while the effectiveness of the second and third rack forces can be decreased accordingly.

[0106] After determining the validity information corresponding to each rack force, the calculation weight of each rack force can be determined according to the validity information, and the actual rack force of the steering shaft can be calculated based on the calculation weight.

[0107] Optionally, the sum of the calculation weights of the first rack force, the second rack force, and the third rack force can be equal to 1. When calculating the actual rack force, the first rack force can be multiplied by its calculation weight, the second rack force by its calculation weight, and the third rack force by its calculation weight. Finally, the results of the three multiplications are added together to obtain the actual rack force of the steering shaft.

[0108] In some possible implementations, in order to improve the reliability of the actual rack force, the actual rack force can also be filtered and / or limited.

[0109] This application provides a method for determining the rack force of a vehicle. If it is necessary to estimate the rack force of a certain steering shaft of a target vehicle, firstly, the force conditions of the two steering wheels on the steering shaft are obtained. Then, based on the force conditions of the steering wheels and the kingpin parameters of the steering shaft, the total kingpin torque of the steering shaft is determined, and the first rack force of the steering shaft is determined from a mechanical perspective based on the total kingpin torque. Secondly, the second rack force of the steering shaft can be determined from a kinematic perspective based on the motion data of the target vehicle. Thirdly, the third rack force of the steering shaft can be determined from the perspective of driving the steering shaft based on the output of the steering motor of the steering shaft. Finally, the actual rack force of the steering shaft can be determined by combining the first, second, and third rack forces based on the actual driving conditions of the target vehicle. In other words, when estimating the rack force of the steering shaft, the rack force can be estimated three times from three perspectives: kingpin force, vehicle kinematics, and drive motor. Then, based on the actual vehicle conditions, the rack forces estimated three times are combined to determine the actual rack force. In this way, by estimating the rack force from multiple aspects, the magnitude of the rack force can be comprehensively determined. By considering the actual driving conditions of the vehicle, the accuracy of rack force estimation can be improved. Therefore, determining the rack force by integrating multiple factors can further enhance its accuracy.

[0110] The above are some specific implementations of the method for determining vehicle rack force provided in the embodiments of this application. Based on this, this application also provides a corresponding vehicle rack force determining device. The vehicle rack force determining device provided in the embodiments of this application will be described below from the perspective of functional modularity.

[0111] See Figure 2 , Figure 2 This is a schematic diagram of a vehicle rack force determining device provided in an embodiment of this application. Specifically, Figure 2 The vehicle rack force determining device 200 shown includes:

[0112] The acquisition unit 210 is used to acquire the force conditions of two steering wheels, the two steering wheels corresponding to the same steering axle of the target vehicle;

[0113] The first calculation unit 220 is used to determine the total kingpin torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft; and to determine the first rack force of the steering shaft based on the total kingpin torque.

[0114] The second calculation unit 230 is used to determine the second rack force of the steering shaft based on the motion data of the target vehicle;

[0115] The third calculation unit 240 is used to determine the third rack force of the steering shaft based on the output of the steering motor of the steering shaft;

[0116] The estimation unit 250 is used to determine the actual rack force of the steering shaft based on the driving conditions of the target vehicle, combined with the first rack force, the second rack force, and the third rack force.

[0117] In some possible implementations, the first calculation unit 220 is specifically used to determine the gravity return torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel based on the force conditions of the two steering wheels and in conjunction with the kingpin parameters of the steering shaft; and to determine the total kingpin torque of each steering wheel based on the gravity return torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel, and to calculate the total kingpin torque of the steering shaft.

[0118] In some possible implementations, the force conditions of the steering wheel are considered in conjunction with the kingpin parameters of the steering shaft; the acquisition unit 210 is also used to acquire the steering wheel angle; the first calculation unit 220 is specifically used to calculate the gravity-correcting torque of the steering wheel based on the support force of the steering wheel, the steering wheel angle, the kingpin offset of the steering wheel, and the kingpin inclination angle of the steering wheel, combined with the geometric relationship between the steering wheel and the kingpin; the force conditions of the steering wheel are used to describe the support force of each steering wheel on the steering shaft; the kingpin parameters of the steering shaft include the kingpin offset and kingpin inclination angle of the steering shaft.

[0119] In some possible implementations, the kingpin parameters of the steering shaft include the kingpin caster angle and kingpin inclination angle of the steering wheel, and the force condition of the steering wheel includes the vertical rotational torque acting on the steering wheel; the first calculation unit 220 is specifically used to determine the correlation between the vertical rotational torque and the main shaft return torque based on the kingpin caster angle and the kingpin outclination angle; and to determine the main shaft return torque based on the correlation and the vertical rotational torque.

[0120] In some possible implementations, the third calculation unit 240 is specifically used to monitor the conversion coefficient and output torque of the steering motor; and to determine the third rack force based on preset motor resistance torque and rack resistance; wherein the motor resistance torque is determined based on the motor inertial torque, motor damping torque and motor friction torque of the steering motor, and the rack resistance is determined based on the rack inertial force, rack damping force and rack friction force of the steering shaft.

[0121] In some possible implementations, the estimation unit 250 is specifically used to determine validity information based on the driving conditions of the target vehicle. The validity information includes validity information corresponding to the first rack force, the second rack force, and the third rack force. The validity information indicates the reliability of the input signal used to calculate the rack force. Based on the validity information, the calculation weights of the first rack force, the second rack force, and the third rack force are determined respectively, and the actual rack force of the steering shaft is calculated.

[0122] This application also provides corresponding control devices, vehicles, computer storage media, and computer program products to implement the technical solutions provided in this application.

[0123] The control device includes a memory and a processor. The memory stores instructions or code, and the processor executes the instructions or code stored in the memory to enable the device to perform the method for determining the rack force of a vehicle as described in any embodiment of this application.

[0124] The vehicle includes multiple wheels and the control device.

[0125] The computer storage medium stores code, and when the code is executed, the device running the code implements the method for determining the rack force of a vehicle as described in any embodiment of this application.

[0126] The computer program product contains instructions. When run on a computer, it causes the computer to perform the method for determining the rack force of a vehicle as described in any embodiment of this application.

[0127] In the embodiments of this application, the terms "first" and "second" (if they exist) are used only as name identifiers and do not represent the order of first and second.

[0128] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that all or part of the steps in the methods of the above embodiments can be implemented by means of software plus a general-purpose hardware platform. Based on this understanding, the technical solution of this application can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as a read-only memory (ROM), magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network communication device such as a router) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0129] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0130] The above description is merely an exemplary implementation of this application and is not intended to limit the scope of protection of this application.

Claims

1. A method for determining the rack force of a vehicle, characterized in that, The method includes: Obtain the force conditions of two steering wheels, which correspond to the same steering axle of the target vehicle; Based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft, the total kingpin torque of the steering shaft is determined. Based on the total kingpin torque, determine the first rack force of the steering shaft; Based on the motion data of the target vehicle, the second rack force of the steering shaft is determined; Based on the output of the steering motor of the steering shaft, the third rack force of the steering shaft is determined; Based on the driving conditions of the target vehicle, the actual rack force of the steering shaft is determined by combining the first rack force, the second rack force, and the third rack force.

2. The method according to claim 1, characterized in that, The determination of the total kingpin torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft includes: Based on the force conditions of the two steering wheels and the kingpin parameters of the steering shaft, the gravity return torque, lateral kingpin torque, longitudinal kingpin torque and kingpin return torque of each steering wheel are determined respectively. Based on the gravity return torque, lateral kingpin torque, longitudinal kingpin torque, and kingpin return torque of each steering wheel, the total kingpin torque of each steering wheel is determined, and the total kingpin torque of the steering shaft is calculated.

3. The method according to claim 2, characterized in that, The determination of the gravity-based self-aligning torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft includes: Obtain the rotation angle of the steering wheel; Based on the supporting force of the steering wheel, the steering wheel's rotation angle, the kingpin offset distance of the steering wheel, and the kingpin inclination angle of the steering wheel, combined with the geometric relationship between the steering wheel and the kingpin, the gravity-correcting torque of the steering wheel is calculated. The force conditions of the steering wheels are used to describe the supporting force of each steering wheel on the steering shaft; the kingpin parameters of the steering shaft include the kingpin offset and kingpin inclination angle.

4. The method according to claim 2, characterized in that, The kingpin parameters of the steering shaft include the kingpin caster angle and kingpin inclination angle of the steering wheel, and the force conditions of the steering wheel include the vertical rotational torque on the steering wheel; The kingpin return torque is obtained by the following method: The relationship between the vertical rotational torque and the spindle return torque is determined based on the kingpin back tilt angle and the kingpin inclination angle. Based on the aforementioned correlation, the spindle return torque is determined in conjunction with the vertical rotational torque.

5. The method according to claim 1, characterized in that, The determination of the third rack force of the steering shaft based on the output of the steering motor of the steering shaft includes: Monitor the conversion coefficient and output torque of the steering motor; The third rack force is determined based on the preset motor resistance torque and rack resistance; The motor resistance torque is determined based on the motor inertial torque, motor damping torque, and motor friction torque of the steering motor, while the rack resistance is determined based on the rack inertial force, rack damping force, and rack friction force of the steering shaft.

6. The method according to any one of claims 1-5, characterized in that, The step of determining the actual rack force of the steering shaft based on the driving conditions of the target vehicle, combined with the first rack force, the second rack force, and the third rack force, includes: Based on the driving conditions of the target vehicle, validity information is determined. The validity information includes validity information corresponding to the first rack force, validity information corresponding to the second rack force, and validity information corresponding to the third rack force. The validity information indicates the reliability of the input signal used to calculate the rack force. Based on the validity information, the calculation weights of the first rack force, the second rack force, and the third rack force are determined respectively, and the actual rack force of the steering shaft is calculated.

7. A device for determining the rack force of a vehicle, characterized in that, The device includes: The acquisition unit is used to acquire the force conditions of two steering wheels, which correspond to the same steering axle of the target vehicle; The first calculation unit is used to determine the total kingpin torque of the steering shaft based on the force conditions of the steering wheel and the kingpin parameters of the steering shaft; and to determine the first rack force of the steering shaft based on the total kingpin torque. The second calculation unit is used to determine the second rack force of the steering shaft based on the motion data of the target vehicle; The third calculation unit is used to determine the third rack force of the steering shaft based on the output of the steering motor of the steering shaft; An estimation unit is used to determine the actual rack force of the steering shaft based on the driving conditions of the target vehicle, combined with the first rack force, the second rack force, and the third rack force.

8. A control device, characterized in that, The control device includes a memory and a processor, the memory being used to store instructions or code, and the processor being used to execute the instructions or code stored in the memory to implement the method as described in any one of claims 1-6.

9. A vehicle, characterized in that, The vehicle includes multiple wheels and the control device as described in claim 8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is run by the processor, the processor performs the method as described in any one of claims 1-4.

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