A car drift correction algorithm

Abstract

This invention belongs to the field of automotive safety technology, specifically relating to a vehicle drift correction algorithm. The algorithm includes the following steps: Step 1, establishing a wheel yaw moment difference calculation model based on the angle difference between the left and right drive shafts; Step 2, establishing a dynamic angle calculation model for the drive shaft universal joint; Step 3, establishing a two-stage deceleration steering system model based on the wheel yaw moment difference calculation model and the drive shaft universal joint dynamic angle calculation model; Step 4, by obtaining the value of the motor compensation target torque, comparing it with a preset threshold, determining whether a warning is needed, if a warning is needed, proceeding to Step 5, otherwise repeating Step 4. This overcomes the shortcomings of existing technologies by calculating in real time the yaw moment difference between the left and right wheels caused by the angle difference of the universal joints at the differential end and wheel end of the left and right drive shafts, thereby calculating the steering motor compensation target torque, determining the steering motor compensation torque based on the threshold, and solving the drift problem at its source.

Description

Technical Field

[0001] This invention belongs to the field of automotive safety technology, specifically relating to an algorithm for correcting vehicle deviation. Background Technology

[0002] Factors causing vehicle pull-off include differences in the universal joint angles at the differential and wheel ends of the left and right drive axles under static and dynamic conditions; differences in load on the left and right wheels; differences in tolerances of left and right suspension components; tire taper; and four-wheel alignment parameters. Among these, the difference in the universal joint angles at the differential and wheel ends of the left and right drive axles has the greatest impact under static and dynamic conditions. Other factors, as long as they meet the overall vehicle design requirements, will not cause pull-off problems. In other words, if the difference in the yaw moment between the left and right wheels caused by the difference in the universal joint angles at the differential and wheel ends of the left and right drive axles is resolved, and the vehicle still pulls off course, it can be basically determined that there is a problem with the vehicle. It is recommended to check the vehicle in the following order: tire pressure, four-wheel alignment, tire wear differences, and chassis structural components. Problems should be repaired promptly to prevent small damages from accumulating and causing component failures. In severe cases, this could lead to traffic accidents, resulting in significant losses and serious negative impacts on users and vehicle manufacturers.

[0003] The following section focuses on the difference in universal joint angles between the differential end and the wheel end of the left and right drive shafts. The transmission route of automotive power is generally engine / motor, transmission, differential, drive shaft, and wheels. Due to the overall vehicle layout, the differential is generally difficult to place in the center of the vehicle, but is usually biased to one side. For the drive shaft, there are two main solutions: (1) Two-stage (see Figure 1 ), with one drive shaft on each side. At this time, the angle difference between the universal joints on the transmission side and the wheel side of the left and right drive shafts is relatively large. When the engine / motor torque is transmitted to the wheel, a relatively large yaw moment difference will be generated, resulting in a deviation problem; (2) Three-section or two-end long handle structure (see Figure 2 Under static conditions, the left and right drive shafts are of equal or nearly equal length. At this time, the angles of the universal joints on the transmission side and wheel side of the left and right drive shafts are equal or nearly equal. When accelerating with a small throttle or a gentle throttle, the powertrain rollover is not obvious, and the angle difference between the universal joints on the transmission side and wheel side of the left and right drive shafts is not significant, so there is no deviation or only slight deviation. However, under high throttle acceleration conditions, the powertrain rollover is larger, which increases the dynamic angle difference between the universal joints on the transmission side and wheel side of the left and right drive shafts. When the engine / motor torque is transmitted to the wheels, a relatively large difference in yaw moment will be generated, resulting in deviation problems.

[0004] (1) Invention: CN108394409A Vehicle and method and apparatus for correcting its deviation and electric power steering system

[0005] The control method of this invention includes acquiring vehicle speed information, calculating vehicle acceleration based on the vehicle speed information, acquiring the wheel speeds of the left and right front wheels, calculating the wheel speed difference between the left and right front wheels, determining the vehicle's steering based on the wheel speed difference, acquiring the steering wheel torque signal, and determining the torque direction based on the torque signal. When the acceleration is greater than a preset acceleration and the torque direction is inconsistent with the vehicle's steering, the vehicle's steering is corrected according to the calibrated correction torque and torque direction. This method can promptly correct deviations that occur during rapid acceleration or deceleration, ensuring driving safety.

[0006] The invention corrects deviations caused by all influencing factors, but fails to identify vehicle problems, resulting in the EPS working under heavy load for a long time, affecting its lifespan, increasing energy consumption, and causing small vehicle problems to accumulate into big problems, causing parts damage, and in severe cases, potential safety hazards.

[0007] (2) Invention: CN113734275B Torque compensation method, power steering system and automobile

[0008] This invention discloses a torque compensation method, a power steering system, and a vehicle. The torque compensation method involves: when the vehicle enters a straight-line acceleration and veering state, a feedforward compensation stage is entered to calculate and obtain a feedforward compensation torque; after the feedback compensation conditions are met, compensation is performed based on the final feedforward compensation torque to obtain a feedback compensation torque, and the final feedforward compensation torque is superimposed on the feedback compensation torque to generate a compensation torque; the compensation torque is superimposed on the power steering system's torque loop to obtain the final power steering torque, and the power steering system's motor is controlled to output the final power steering torque. The feedforward compensation stage has a fast response; as long as the vehicle is in a straight-line acceleration and veering state, the feedforward compensation stage can immediately output the feedforward compensation torque to reduce the veering amount; the feedback compensation stage can reduce the hand force to the target torque, reducing the hand force maintained during veering and reducing driver fatigue. The feedforward compensation torque and the feedback compensation torque can achieve the best effect in correcting veering.

[0009] The invention corrects deviations caused by all influencing factors, but fails to identify vehicle problems, resulting in the EPS working under heavy load for a long time, affecting its lifespan, increasing energy consumption, and causing small vehicle problems to accumulate into big problems, causing parts damage, and in severe cases, potential safety hazards.

[0010] (3) Invention: CN114013500A A control method for suppressing vehicle deviation based on electric power steering

[0011] This invention discloses a control method for suppressing vehicle drift based on electric power steering, belonging to the field of automotive technology. Specifically, it is a control method that actively applies steering torque to the vehicle when the electric power steering system detects a tendency to drift, thereby suppressing vehicle drift. This invention utilizes a series of signals representing the vehicle's driving posture on the CAN bus monitored by the vehicle's EPS to identify and judge the vehicle's drift tendency. Based on different degrees of drift tendency, it actively applies different steering compensation torques, thereby suppressing vehicle drift. The beneficial effects of this invention are: it can automatically identify vehicle drift tendencies and actively apply compensation torques to reduce drift; it automatically repairs vehicle faults without the user's awareness, reducing user complaints; in the aftermarket, it eliminates the need for suspension system component replacement and four-wheel alignment, saving costs, labor, and time.

[0012] The invention corrects deviations caused by all influencing factors, but fails to identify vehicle problems, resulting in the EPS working under heavy load for a long time, affecting its lifespan, increasing energy consumption, and causing small vehicle problems to accumulate into big problems, causing parts damage, and in severe cases, potential safety hazards.

[0013] (4) CN114274947A A vehicle driving stability intelligent control device, method and automobile

[0014] This invention discloses a vehicle driving stability intelligent control device, method, and automobile, including: a front wheel angle sensor mounted on the upper end of the front shock absorber; a left torque sensor and a right torque sensor mounted on the left and right driveshaft CV joints, respectively; the front wheel angle sensor, left torque sensor, and right torque sensor are connected to the automobile's EPS power steering system and ESP braking control system. This control device compares the front wheel angle obtained by the front wheel angle sensor mounted on the upper end of the shock absorber with the steering wheel angle obtained by the steering wheel angle sensor. If a deviation exists, it further compares the torque difference between the left and right half-shafts obtained by the torque sensor mounted on the driveshaft CV joints. The system determines whether there is torque deviation. Combined with auxiliary wheel speed sensors and a vehicle yaw sensor, the control system employs corresponding strategies to ensure vehicle driving stability and safety.

[0015] The aforementioned invention, which places the left and right torque sensors on the drive shaft CV joint, is difficult to implement in mass-produced vehicles. Furthermore, it does not elaborate on the calculation process of the difference in driving torque between the left and right drive shafts on the yaw torque of the wheels, and it lacks a warning function.

[0016] (5) CN114954491A A learning-based method for compensating for vehicle deviation during rapid acceleration

[0017] The invention corrects deviations caused by all influencing factors, but fails to identify vehicle problems, resulting in the EPS working under heavy load for a long time, affecting its lifespan, increasing energy consumption, and causing small vehicle problems to accumulate into big problems, causing parts damage, and in severe cases, potential safety hazards. Summary of the Invention

[0018] The purpose of this invention is to provide a vehicle drift correction algorithm that overcomes the shortcomings of existing technologies. By modeling, it calculates in real time the difference in the angle of the universal joints at the differential end and wheel end of the left and right drive shafts, which leads to the difference in the yaw torque of the left and right wheels. Then, it calculates the target torque for steering motor compensation and determines the steering motor compensation torque based on the threshold, thus solving the drift problem at its source.

[0019] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0020] A vehicle drift correction algorithm, the algorithm comprising the following steps:

[0021] Step 1: Establish a calculation model for the wheel yaw moment difference based on the angle difference between the left and right drive shafts;

[0022] Step 2: Establish a dynamic angle calculation model for the drive shaft universal joint;

[0023] Step 3: Establish a two-stage deceleration steering system model based on the wheel yaw moment difference calculation model and the drive shaft universal joint dynamic angle calculation model;

[0024] Step 4: Obtain the value of the motor compensation target torque, compare it with the preset threshold, and determine whether an early warning is needed. If an early warning is needed, proceed to Step 5; otherwise, repeat Step 4.

[0025] Step 5: Issue a warning signal that the car is veering off course via the warning module, prompting the driver to stop and check as soon as possible.

[0026] Furthermore, the expression for the wheel yaw moment difference calculation model described in step one is as follows:

[0027] ΔM=M L -M R

[0028] Where ΔM is the difference in yaw moment between the left and right wheels, M L M is the yaw moment of the left wheel. R This is the yaw moment of the right wheel.

[0029] Furthermore, the yaw moment M of the left wheel L The expression is:

[0030]

[0031] Where, k L T is the calibration coefficient. e Let i0 be the total torque generated by the power system, i0 be the total reduction ratio of the power system, η0 be the total transmission efficiency of the power system, and α be the total torque generated by the power system. L β is the angle between the universal joint at the left drive shaft differential end and the shaft. L R1 is the angle between the universal joint at the wheel end of the left drive axle and the axle, R2 is the kingpin offset, and R3 is the tire rolling radius.

[0032] Furthermore, the yaw moment M of the right wheel R The expression is:

[0033]

[0034] Where, k R α is the calibration coefficient. R β is the angle between the universal joint at the right drive shaft differential end and the shaft. R This is the angle between the universal joint at the wheel end of the right drive axle and the axle.

[0035] Furthermore, the dynamic angle calculation model of the drive shaft universal joint mentioned in step two is related to wheel bounce, and the value of wheel bounce is obtained through the vehicle height sensor or shock absorber.

[0036] Furthermore, the expression for the two-stage deceleration steering system model described in step three is as follows:

[0037]

[0038] Among them, T M For the target torque of motor compensation, i1 is the first-stage reduction ratio of the motor; η1 is the first-stage reduction transmission efficiency of the motor; i2 is the second-stage reduction ratio of the motor; η2 is the second-stage reduction transmission efficiency of the motor; L is the distance between the ball end of the outer tie rod and the axis of the kingpin; θ1 is the angle between the inner and outer tie rods; θ2 is the angle between the line connecting the intersection of the ball end of the outer tie rod and the axis of the kingpin and the outer tie rod; and r2 is the pitch circle radius of the steering gear pinion.

[0039] Furthermore, in step four, the value of the motor compensation target torque is obtained and compared with a preset threshold to determine whether an early warning is needed. The specific strategy expression is as follows:

[0040]

[0041] Where T is the motor compensation torque, Tv is the threshold of the motor compensation torque, and T... M To compensate the target torque for the motor.

[0042] Furthermore, in step four, before obtaining the value of the motor compensation target torque, it is necessary to collect the vehicle speed, lateral acceleration, yaw rate and steering wheel angle data in real time, and determine whether the vehicle is traveling in a straight line. If the vehicle is traveling in a straight line, then obtain the value of the motor compensation target torque.

[0043] Furthermore, the strategy for determining whether a vehicle is traveling in a straight line includes:

[0044] (1) The vehicle speed V is greater than the vehicle speed threshold Vv;

[0045] (2) The lateral acceleration a is less than the lateral acceleration threshold av;

[0046] (3) The yaw velocity ω is less than the yaw velocity threshold ωv;

[0047] (4) The steering wheel angle δ is within the threshold range [δv1, δv2];

[0048] When (1)-(4) are satisfied simultaneously, the vehicle is determined to be traveling in a straight line.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. This invention uses modeling to calculate in real time the difference in yaw torque between the left and right wheels caused by the difference in universal joint angles at the differential end and wheel end of the left and right drive shafts. It then calculates the target torque for steering motor compensation and determines the compensation torque based on a threshold, thus solving the problem of vehicle drift at its source. Simultaneously, a warning module operates in real time. When the vehicle is traveling straight, it reads the torque from the steering wheel sensor and determines whether the vehicle is drifting based on a threshold. If drifting occurs, it alerts the user to have the vehicle inspected promptly.

[0051] 2. This invention can minimize the working time of the steering motor, improve the life of the steering system, save energy and protect the environment. At the same time, it can identify vehicle problems in a timely manner, preventing small problems from accumulating into big problems, causing damage or failure of suspension and steering system components, and in extreme cases, causing accidents, resulting in significant losses and adverse effects on users and OEMs. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of a two-section structure.

[0053] Figure 2 This is a schematic diagram of a three-section structure / two-section long-handle structure.

[0054] Figure 3 This is a schematic diagram of the algorithm flow of the present invention.

[0055] Figure 4 This is a schematic diagram showing the fitting results of the dynamic angle calculation model for the universal joint of the left-side drive shaft of a certain vehicle model.

[0056] Figure 5 This is a schematic diagram showing the fitting results of the dynamic angle calculation model for the universal joint of the right-side drive shaft of a certain vehicle model. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] like Figure 3 As shown, the vehicle drift correction algorithm of the present invention includes the following steps:

[0059] Step 1: Establish a calculation model for the wheel yaw moment difference based on the angle difference between the left and right drive shafts;

[0060] Yaw moment M of the left wheel L The expression is:

[0061]

[0062] Where, k L T is the calibration coefficient. e Let i0 be the total torque generated by the power system, i0 be the total reduction ratio of the power system, η0 be the total transmission efficiency of the power system, and α be the total torque generated by the power system. L β is the angle between the universal joint at the left drive shaft differential end and the shaft. L R1 is the angle between the universal joint at the wheel end of the left drive axle and the axle, R2 is the kingpin offset, and R3 is the tire rolling radius.

[0063] Yaw moment M of the right wheel R The expression is:

[0064]

[0065] Where, k R α is the calibration coefficient. R β is the angle between the universal joint at the left drive shaft differential end and the shaft. R The angle between the universal joint at the wheel end of the left drive axle and the axle;

[0066] The expression for the wheel yaw moment difference calculation model is as follows:

[0067] ΔM=M L -M R

[0068] Where ΔM is the difference in yaw moment between the left and right wheels, M LM is the yaw moment of the left wheel. R This is the yaw moment of the right wheel.

[0069] Step 2: Establish a dynamic angle calculation model for the drive shaft universal joint;

[0070] The dynamic angle calculation model of the drive shaft universal joint is related to wheel runout, and the value of wheel runout is obtained through vehicle height sensor or shock absorber; the relationship between the dynamic angle of the drive shaft universal joint and wheel runout can be obtained by data fitting, which may vary depending on the vehicle parameters and requires specific calibration for specific vehicle models.

[0071] Below is an example of the fitting results for a certain car model:

[0072] α L =f1(h)=-5.7*h 4 -1.2*h 3 +15.8*h 2 +h+3.2

[0073] β L =f2(h)=-4.2*h 4 -1.3*h 3 +11.9*h 2 +0.2*h+3.1

[0074] The fitting results of the dynamic angle calculation model for the universal joint of the left vehicle drive axle are shown below. Figure 3 ;

[0075] α R =f3(h)=-7.2*h 4 -1.5*h 3 +19.6*h 2 +1.3*h+4

[0076] β R =f4(h)=-5.7*h 4 -1.6*h 3 +16.1*h 2 +0.4*h+3.9

[0077] The fitting results of the dynamic angle calculation model for the universal joint of the right vehicle drive axle are shown below. Figure 4 ;

[0078] Where h represents wheel bounce, and the unit is percentage.

[0079] Step 3: Establish a two-stage deceleration steering system model based on the wheel yaw moment difference calculation model and the drive shaft universal joint dynamic angle calculation model;

[0080] The expression for the two-stage deceleration steering system model is:

[0081]

[0082] Among them, T M For the target torque of motor compensation, i1 is the first-stage reduction ratio of the motor; η1 is the first-stage reduction transmission efficiency of the motor; i2 is the second-stage reduction ratio of the motor; η2 is the second-stage reduction transmission efficiency of the motor; L is the distance between the ball end of the outer tie rod and the axis of the kingpin; θ1 is the angle between the inner and outer tie rods; θ2 is the angle between the line connecting the intersection of the ball end of the outer tie rod and the axis of the kingpin and the outer tie rod; and r2 is the pitch circle radius of the steering gear pinion.

[0083] Step 4: Obtain the value of the motor compensation target torque, compare it with the preset threshold, and determine whether an early warning is needed. If an early warning is needed, proceed to Step 5; otherwise, repeat Step 4.

[0084] By acquiring the target torque value of the motor compensation and comparing it with a preset threshold, it is determined whether an early warning is needed. The specific strategy expression is as follows:

[0085]

[0086] Where T is the motor compensation torque, Tv is the threshold of the motor compensation torque, and T... M To compensate the target torque for the motor.

[0087] Before obtaining the value of the motor compensation target torque, it is necessary to collect the vehicle speed, lateral acceleration, yaw rate and steering wheel angle data in real time, and determine whether the vehicle is traveling in a straight line. If the vehicle is traveling in a straight line, then obtain the value of the motor compensation target torque.

[0088] The strategies for determining whether a vehicle is traveling in a straight line include:

[0089] (1) The vehicle speed V is greater than the vehicle speed threshold Vv;

[0090] (2) The lateral acceleration a is less than the lateral acceleration threshold av;

[0091] (3) The yaw velocity ω is less than the yaw velocity threshold ωv;

[0092] (4) The steering wheel angle δ is within the threshold range [δv1, δv2];

[0093] When (1)-(4) are satisfied simultaneously, the vehicle is determined to be traveling in a straight line.

[0094] Step 5: Issue a warning signal that the car is veering off course via the warning module, prompting the driver to stop and check as soon as possible;

[0095] The reminder methods include, but are not limited to: instrument panel, head-up display, voice, etc., and the reminder content includes, but is not limited to: "The vehicle has a problem with pulling to one side. It is recommended to check the tire pressure, four-wheel alignment, steering structure, and chassis in that order."

[0096] In summary, the vehicle drift correction algorithm described in this invention models and calculates in real time the difference in yaw torque between the left and right wheels caused by the difference in universal joint angles at the differential end and wheel end of the left and right drive axles. It then calculates the target torque for steering motor compensation and determines the compensation torque based on a threshold, thus solving the drift problem at its source. Simultaneously, the warning module operates in real time. When the vehicle is traveling straight, it reads the torque from the steering wheel sensor and determines whether the vehicle is drifting based on a threshold. If drifting occurs, it alerts the user to have the vehicle inspected promptly.

[0097] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A vehicle drift correction algorithm, characterized in that: The algorithm includes the following steps: Step 1: Establish a calculation model for the wheel yaw moment difference based on the angle difference between the left and right drive shafts; Step 2: Establish a dynamic angle calculation model for the drive shaft universal joint; Step 3: Establish a two-stage deceleration steering system model based on the wheel yaw moment difference calculation model and the drive shaft universal joint dynamic angle calculation model; Step 4: Obtain the value of the motor compensation target torque, compare it with the preset threshold, and determine whether an early warning is needed. If an early warning is needed, proceed to Step 5; otherwise, repeat Step 4. Step 5: Issue a warning signal that the car is veering off course via the warning module, prompting the driver to stop and check as soon as possible; The expression for the wheel yaw moment difference calculation model described in step one is: ΔM=M L -M R Where ΔM is the difference in yaw moment between the left and right wheels, M L M is the yaw moment of the left wheel. R This is the yaw moment of the right wheel; The yaw moment M of the left wheel L The expression is: Where, k L T is the calibration coefficient. e Let i0 be the total torque generated by the power system, i0 be the total reduction ratio of the power system, η0 be the total transmission efficiency of the power system, and α be the total torque generated by the power system. L β is the angle between the universal joint at the left drive shaft differential end and the shaft. L R1 is the angle between the universal joint at the wheel end of the left drive axle and the axle, R2 is the kingpin offset, and R3 is the tire rolling radius. The yaw moment M of the right wheel R The expression is: Where, k R α is the calibration coefficient. R β is the angle between the universal joint at the right drive shaft differential end and the shaft. R This is the angle between the universal joint at the wheel end of the right drive axle and the axle.

2. The vehicle drift correction algorithm according to claim 1, characterized in that: In step four, the target torque value for motor compensation is obtained and compared with a preset threshold to determine whether an alert is needed. The specific strategy expression is as follows: Where T is the motor compensation torque, Tv is the threshold of the motor compensation torque, and T... M To compensate the target torque for the motor.

3. The vehicle drift correction algorithm according to claim 1, characterized in that: In step four, before obtaining the value of the motor compensation target torque, it is necessary to collect the vehicle speed, lateral acceleration, yaw rate and steering wheel angle data in real time, and determine whether the vehicle is traveling in a straight line. If the vehicle is traveling in a straight line, then obtain the value of the motor compensation target torque.

4. The vehicle drift correction algorithm according to claim 3, characterized in that: The strategies for determining whether a vehicle is traveling in a straight line include: (1) The vehicle speed V is greater than the vehicle speed threshold Vv; (2) The lateral acceleration a is less than the lateral acceleration threshold av; (3) The yaw velocity ω is less than the yaw velocity threshold ωv; (4) The steering wheel angle δ is within the threshold range [δv1, δv2]; When (1)-(4) are satisfied simultaneously, the vehicle is determined to be traveling in a straight line.

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