A steering accuracy compensation method for a vehicle steering system

Abstract

The present invention relates to the technical field of vehicle steering systems, and in particular to a steering accuracy compensation method for a vehicle steering system, comprising: S1: selecting a turning radius, and generating a first functional relationship between a left steering wheel and a rack displacement, and a second functional relationship between a right steering wheel and a rack displacement according to the turning radius; S2: judging whether the vehicle steering system meets the accuracy requirement according to the first functional relationship and the second functional relationship; if so, turning to S3; S3: selecting a wheel on one side as a reference point, and calculating the steering deviation corresponding to the turning radius; S4: performing accuracy compensation according to the steering deviation. The beneficial effect is that by constructing a functional relationship between the steering wheel and the rack displacement under a specific steering radius, the steering deviation caused by the steering system design can be accurately judged, and the steering deviation is quantified, thereby avoiding the problem that the steering deviation of the vehicle steering system cannot be accurately obtained in the prior art, and achieving effective compensation for the steering accuracy of the vehicle steering system.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle steering systems, and in particular to a steering accuracy compensation method for a vehicle steering system. Background Art

[0002] The vehicle steering system refers to a series of devices and mechanical structures installed on the car to change or maintain the direction of the car's driving or reverse. Generally speaking, the principle of this type of system to achieve car steering is that the driver uses a set of special mechanisms, such as interconnected and meshing racks, swing arms, connecting rods, etc., to make the wheels on the car's steering axle (usually the front axle) deflect a certain angle relative to the longitudinal axis of the car, thereby making the vehicle drive in a specific direction. Because the vehicle steering system usually needs to rely on a series of mechanical transmission mechanisms to deflect the wheels when achieving car steering. Therefore, some defects in the mechanical structure itself, such as the phase difference when different gears are meshing and the interference between mechanical components, will cause errors in the steering system, and thus make the vehicle steering system unable to maintain a relatively accurate direction.

[0003] In the prior art, there are corresponding improvement schemes to reduce the error of the vehicle steering system for the above-mentioned problems. For example, by changing the production and assembly process of the steering rack to improve the overall mechanical accuracy of the steering system, thereby avoiding the influence of factors such as clamping error on the steering accuracy. However, in the actual implementation process, the inventors found that the prior art usually only improves the vehicle steering system through process and dynamics, which has a relatively limited improvement in the accuracy of the steering system and does not substantially solve the steering error problem caused by the design defects of the steering system itself; at the same time, some steering system optimization schemes for specific vehicles, because the steering system is composed of multiple nonlinear systems, such optimization schemes need to rely on manual experience debugging and are not universal. Summary of the invention

[0004] In view of the above problems existing in the prior art, a steering accuracy compensation method for a vehicle steering system is now provided.

[0005] The specific technical solutions are as follows:

[0006] A steering accuracy compensation method for a vehicle steering system, comprising:

[0007] Step S1: selecting a turning radius, and generating a first functional relationship between the displacement of the left steering wheel and the rack, and a second functional relationship between the displacement of the right steering wheel and the rack according to the turning radius;

[0008] Step S2: judging whether the vehicle steering system meets the accuracy requirement according to the first functional relationship and the second functional relationship;

[0009] If not, go to step S3;

[0010] If yes, end the accuracy compensation process;

[0011] Step S3: Select one side of the wheel as a reference point and calculate the steering deviation corresponding to the turning radius;

[0012] Step S4: performing accuracy compensation according to the steering deviation.

[0013] Preferably, the step S1 comprises:

[0014] Step S11: generating a left steering wheel angle and a first rack displacement corresponding to the left steering wheel angle, and a right steering wheel angle and a second rack displacement corresponding to the right steering wheel angle respectively according to the turning radius;

[0015] Step S12: generating the first functional relationship and the second functional relationship according to the left steering wheel angle, the first rack displacement, the right steering wheel angle and the second rack displacement.

[0016] Preferably, in step S2, the method for judging whether the vehicle steering system meets the accuracy requirement according to the first functional relationship and the second functional relationship includes:

[0017] calculate

[0018] When Δs(R)=0, it indicates that the accuracy requirement is met; when Δs(R)≠0, it indicates that the accuracy requirement is not met; wherein Δs(R) is the steering deviation function under the turning radius, s g is the rack displacement in the first functional relationship, s d is the rack displacement in the second functional relationship; A c is the first distance between the steering wheel and the rack, which is calculated as Wherein, K is the wheelbase of the vehicle steering system, and l3 is the length of the rack;

[0019] l1 is the length of the first connecting rod, α g is the actual turning angle of the left steering wheel, α d is the actual turning angle of the right steering wheel, l2 is the length of the second connecting rod, and d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel.

[0020] Preferably, in step S3, the method for generating the steering deviation is:

[0021]

[0022] Among them, D 偏差is the steering deviation, L is the wheelbase of the vehicle steering system, K is the track width of the vehicle steering system, β g is the actual turning angle of the left steering wheel, β d is the actual turning angle of the right steering wheel.

[0023] Preferably, in step S4, the method for performing accuracy compensation according to the steering deviation includes:

[0024] A maximum permissible deviation is generated according to the steering deviation, and then a linkage geometry parameter of the vehicle steering system is adjusted according to the maximum permissible deviation.

[0025] Preferably, in step S4, the method for performing accuracy compensation according to the steering deviation includes:

[0026] generating a compensation input value according to the steering deviation, and then controlling the vehicle steering system using the compensation input value to achieve the steering radius;

[0027] Preferably, the method for generating the compensation input value includes:

[0028]

[0029] Among them, R 实际 is the compensation input value, R is the turning radius, L is the wheelbase of the vehicle steering system, K is the track width of the vehicle steering system, β g is the actual turning angle of the left steering wheel, β d is the actual turning angle of the right steering wheel.

[0030] Preferably, the first functional relationship includes:

[0031] Among them, β g is the actual turning angle of the left steering wheel, L is the wheelbase of the vehicle steering system, K is the track of the vehicle steering system, d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel, l1 is the length of the first connecting rod, l2 is the length of the second connecting rod, l3 is the length of the rack, and s is the rack displacement.

[0032] Preferably, the second functional relationship includes: Among them, β d is the actual turning angle of the right steering wheel, L is the wheelbase of the vehicle steering system, K is the track of the vehicle steering system, d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel, l1 is the length of the first connecting rod, l2 is the length of the second connecting rod, l3 is the length of the rack, and s is the rack displacement.

[0033] The above technical solution has the following advantages or beneficial effects: by constructing a functional relationship between the steering wheel and the rack displacement under a specific steering radius, the steering deviation caused by the steering system design is accurately determined, and the steering deviation is quantified, thereby avoiding the problem in the prior art that the steering deviation of the vehicle steering system cannot be accurately obtained, and achieving effective compensation for the steering accuracy of the vehicle steering system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The embodiments of the present invention will be described more fully with reference to the attached drawings, which are provided for illustration and description only and are not intended to limit the scope of the present invention.

[0035] Figure 1 A schematic diagram of a steering system applicable to the present invention;

[0036] Figure 2 A schematic diagram of another steering system applicable to the present invention;

[0037] Figure 3 It is an overall schematic diagram of the method in the embodiment of the present invention;

[0038] Figure 4 Schematic diagram of sub-steps of step S1 in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0042] The present invention comprises:

[0043] A steering accuracy compensation method for a vehicle steering system is suitable for Figure 1 and Figure 2 The vehicle steering system shown;

[0044] Specifically, the automobile steering system includes a left front wheel g, a left first link AB and a right first link EF both of which are l1 in length, a left second link BC and a right second link DE both of which are l2 in length, a rack CD with a length of l3 and a right front wheel d. Among them, the two ends of the rack CD are respectively connected to the left second link BC and the right second link DE at one end close to the center axis of the vehicle. Points A and F in the figure are swing arm fixing points, and the left front wheel g and the right front wheel d are arranged outside the swing arm fixing point, and are rotatably connected to the left second link BC and the right second link DE through the swing arm. The swing arm is an L-shaped structure, and its corner is arranged on the swing arm fixing point, one end is connected to the left front wheel g or the right front wheel d, and the other end is connected to the left second link BC or the right second link DE as the left first link AB or the right first link EF. Driven by the steering motor and the steering rod, the rack CD reciprocates along the Y-axis direction shown in the figure to push or pull the left second link BC and the right second link DE to move. Both ends of the left second link BC and the right second link DE are rotation connection points, so that the swing arm can rotate the left front wheel g and the right front wheel d at a fixed angle under the drive of the left second link BC or the right second link DE. Figure 1 and Figure 2 The difference is that Figure 1 The vehicle steering system shown in , which is entirely arranged in front of the front axle of the vehicle, is referred to herein as an external steering system; Figure 2 The vehicle steering system shown in the figure is arranged as a whole behind the front axle of the vehicle and is referred to as a built-in steering system.

[0045] If Figure 3 As shown, the steering accuracy compensation method specifically includes:

[0046] Step S1: selecting a turning radius, and generating a first functional relationship between the displacement of the left steering wheel and the rack, and a second functional relationship between the displacement of the right steering wheel and the rack according to the turning radius;

[0047] Step S2: judging whether the vehicle steering system meets the accuracy requirement according to the first functional relationship and the second functional relationship;

[0048] If not, go to step S3;

[0049] If yes, end the accuracy compensation process;

[0050] Step S3: Select one side of the wheel as a reference point and calculate the steering deviation corresponding to the turning radius;

[0051] Step S4: Perform accuracy compensation according to the steering deviation.

[0052] Specifically, for the above two steering systems, the prior art is difficult to effectively analyze the overall system because its overall design is composed of multiple nonlinear systems, such as the rotational connection relationship between the first connecting rod and the second connecting rod, the rotational connection relationship between the second connecting rod and the rack, and the rotation of the connecting rods on both sides driven by the same rack, so it is difficult to obtain an analytical relationship for steering accuracy, and it can only be improved from the perspective of process and dynamics. To address this problem, in this embodiment, through the comparison of intermediate variables, that is, the first functional relationship and the second functional relationship under a specific turning radius, it is determined whether the vehicle steering system has a steering deviation, and a derivative function for steering accuracy is established, thereby realizing the calculation of the steering deviation and the accuracy compensation process, thereby improving the design accuracy of the vehicle steering system.

[0053] Furthermore, in order to achieve a better analysis effect on the vehicle steering system, in this embodiment, by respectively generating a first functional relationship and a second functional relationship, the motion relationship between the steering wheel on the left side of the vehicle and the rack displacement, and the motion relationship between the steering wheel on the left side of the vehicle and the rack displacement are independently analyzed, thereby achieving a better analysis effect.

[0054] In a preferred embodiment, Figure 4 As shown, step S1 includes:

[0055] Step S11: generating a left steering wheel angle and a first rack displacement corresponding to the left steering wheel angle, and a right steering wheel angle and a second rack displacement corresponding to the right steering wheel angle respectively according to the turning radius;

[0056] Step S12: generating a first functional relationship and a second functional relationship according to the left steering wheel angle, the first rack displacement, the right steering wheel angle and the second rack displacement.

[0057] It should be noted that the first rack displacement and the second rack displacement are rack displacements generated by independently analyzing the left steering wheel and the right steering wheel, and physically correspond only to the same rack of the vehicle steering system.

[0058] Specifically, for the above-mentioned steering system, the kinematic connection relationship of the steering system can be obtained as shown in Table 1 below:

[0059]

[0060] Table 1

[0061] For a specific turning radius R, the ideal turning angle of the left steering wheel is β g|JT , the ideal turning angle of the right steering wheel is β d|JT , the actual turning angle of the left steering wheel is β g , the actual turning angle of the right steering wheel is β d .

[0062] The main parameters are shown in Table 2:

[0063]

[0064]

[0065] In this article ± or Corresponding to the built-in / external layouts respectively.

[0066] Table 2 can further provide the basic relationship shown in Table 3:

[0067]

[0068]

[0069] Table 3

[0070] In this embodiment, for a specific turning radius R, the ideal turning angle of the left steering wheel can be obtained: Ideal turning angle of right steering wheel

[0071] Furthermore, the length of the second connecting rod can be obtained based on the geometric relationship:

[0072] in

[0073] Therefore, the vector equation can be derived based on the geometric relationship: Expand and simplify to get:

[0074] A d sin(β d +γ)+B d cos(β d +γ)+C d =0;

[0075] Solve to get the functional relationship between the left wheel rotation angle and rack displacement:

[0076]

[0077] Among them: A g = ±2dl1; B g =2l1(A c ±s);

[0078] According to the geometric relationship, the vector equation can be written: Expand and simplify to get:

[0079] A g sin(βg -γ)+B g cos(β g -γ)+C g =0

[0080] Solve to get the functional relationship between the left wheel rotation angle and rack displacement:

[0081]

[0082] in:

[0083] like Figure 1 In the case of medium-external placement, select the left steering wheel as a reference to calculate the actual steering angle of the right steering wheel, and calculate the steering deviation through comparison.

[0084]

[0085]

[0086] The left and right wheel turning angles β can be obtained g and β d Functional relationship with rack displacement (s).

[0087] Furthermore, based on the vector equation:

[0088] available:

[0089]

[0090] in:

[0091] Thus, the rack displacement (s) and the actual steering angle β of the left steering wheel are obtained. g and the actual turning angle β of the right steering wheel d The functional relationship of .

[0092] In a preferred embodiment, in step S2, the method for determining whether there is a steering deviation according to the first functional relationship and the second functional relationship includes:

[0093] calculate

[0094] When Δs(R)=0, it indicates that there is no steering deviation; when Δs(R)≠0, it indicates that there is a steering deviation;

[0095] Where Δs(R) is the steering deviation function under the turning radius, s g is the rack displacement in the first functional relationship, s d is the rack displacement in the second functional relationship; Ac is the first distance between the steering wheel and the rack, which is calculated as Among them, K is the wheelbase of the vehicle steering system, l3 is the length of the rack; l1 is the length of the first connecting rod, α g is the actual turning angle of the left steering wheel, α d is the actual turning angle of the right steering wheel, l2 is the length of the second connecting rod, and d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel.

[0096] Specifically, after the first functional relationship and the second functional relationship are generated, in this embodiment, an intermediate variable Δs=s is introduced. g -s d , thus realizing the quantification of steering deviation.

[0097] Specifically:

[0098]

[0099] Then take the derivative of Δs with respect to the turning radius R:

[0100]

[0101] Then we can get When it approaches 0, the steering deviation gradually decreases.

[0102] In a preferred embodiment, in step S3, the method for generating the steering deviation is:

[0103]

[0104] Among them, D 偏差 is the steering deviation, L is the wheelbase of the vehicle steering system, K is the track width of the vehicle steering system, β g is the actual turning angle of the left steering wheel, β d is the actual turning angle of the right steering wheel.

[0105] Specifically, given the turning radius R, due to the instantaneous rotation center C of the left and right steering wheels AV , P AV The instantaneous rotation center C during ideal steering JT Or P does not overlap, in The deviation in direction is: X, Y, and the deviation distance between the two instant centers is defined as the theoretical deviation D 偏差 .

[0106]

[0107] Expand to get:

[0108] In a preferred embodiment, in step S4, the method for performing accuracy compensation according to the steering deviation includes:

[0109] A maximum permissible deviation is generated according to the steering deviation, and then a linkage geometric parameter of the vehicle steering system is adjusted according to the maximum permissible deviation.

[0110] In a preferred embodiment, in step S4, the method for performing accuracy compensation according to the steering deviation includes:

[0111] generating a compensation input value based on the steering deviation, and then controlling the vehicle steering system using the compensation input value to achieve a steering radius;

[0112] In a preferred embodiment, the method for generating the compensation input value includes:

[0113]

[0114] Among them, R 实际 is the compensation input value, R is the turning radius, L is the wheelbase of the vehicle steering system, K is the track width of the vehicle steering system, β g is the actual turning angle of the left steering wheel, β d is the actual turning angle of the right steering wheel.

[0115] In a preferred embodiment, the first functional relationship includes:

[0116] Among them, β g is the actual turning angle of the left steering wheel, L is the wheelbase of the vehicle steering system, K is the track of the vehicle steering system, d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel, l1 is the length of the first connecting rod, l2 is the length of the second connecting rod, l3 is the length of the rack, and s is the rack displacement.

[0117] In a preferred embodiment, the second functional relationship includes:

[0118] Among them, β d is the actual turning angle of the right steering wheel, L is the wheelbase of the vehicle steering system, K is the track of the vehicle steering system, d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel, l1 is the length of the first connecting rod, l2 is the length of the second connecting rod, l3 is the length of the rack, and s is the rack displacement.

[0119] Based on the above formula, we can start from the design of the vehicle steering system to obtain a high-precision steering system. 偏差The maximum value is taken as one of the design goals, and the relevant geometry and processing technology are used as constraints (maximum rack stroke, maximum steering wheel process angle, maximum rod length of the connecting rod mechanism, etc.). The rack movement is used as input to simulate the steering process, and the geometric dimensions L1, L3, d, etc. of the connecting rod mechanism components in the steering system are changed one by one. Through the iterative method, the component geometric relationship cluster that meets the accuracy requirements is found, thereby achieving the purpose of optimal design.

[0120] Furthermore, the installation height of the rack can be further adjusted, and the specific steps are as follows:

[0121] Step A1: Build a 3D model and introduce the rack installation height variable h

[0122] Step A2: Establish a vector equation to obtain β G (h,s),β d Function expression of (h,s)

[0123] Step A3: Find the derivative function equation or Solve for β as h changes g(Max) or β d(Max) The maximum value of the left or right wheel angle swing,

[0124] Step A4: Find β gMax =0 or β dMax = h value when 0.

[0125] In another embodiment, for an existing vehicle steering system, the input value actually input into the vehicle steering system can be adjusted by adopting a method of generating a compensation input value, so that when the vehicle steering system adopts the compensation input value for steering, both the left steering wheel and the right steering wheel can reach an ideal turning angle for a specific turning radius.

[0126] Given a desired turning radius R, steering deviations can result in underturns or overturns.

[0127] Add compensation ΔR to the turning radius value R: R 实际 =R+ΔR,

[0128] ΔR: ΔR>0 when over-rotating, ΔR<0 when under-rotating.

[0129] A simplified compensation method can be used to 偏差 Value The direction component ΔY is used as the compensation value of the turning radius:

[0130]

[0131] in:

[0132] It can be concluded that:

[0133] R 实际 As the compensation input value of the actual input vehicle steering system, so as to achieve better steering accuracy.

[0134] The beneficial effects of the present invention are as follows: by geometrically analyzing the components of a vehicle steering system at a specific turning radius, a functional relationship between a steering wheel and a rack is effectively established, and an intermediate variable Δs is introduced based on the functional relationship between the left and right sides, thereby achieving quantification of the steering deviation value, and then the basic parameters of the vehicle steering system can be analyzed according to the quantified steering deviation value, thereby achieving improvement in the design accuracy of the vehicle steering system at the design level, and also achieving steering accuracy compensation for the actual vehicle steering system, thereby improving the accuracy of the vehicle steering system.

[0135] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A steering accuracy compensation method for a vehicle steering system, It is characterized in that include: Step S1: selecting a turning radius, and generating a first functional relationship between the displacement of the left steering wheel and the rack, and a second functional relationship between the displacement of the right steering wheel and the rack according to the turning radius; Step S2: judging whether the vehicle steering system meets the accuracy requirement according to the first functional relationship and the second functional relationship; If not, go to step S3; If yes, end the accuracy compensation process; Step S3: Select one side of the wheel as a reference point and calculate the steering deviation corresponding to the turning radius; Step S4: performing accuracy compensation according to the steering deviation.

2. The steering accuracy compensation method according to claim 1, It is characterized in that The step S1 comprises: Step S11: generating a left steering wheel angle and a first rack displacement corresponding to the left steering wheel angle, and a right steering wheel angle and a second rack displacement corresponding to the right steering wheel angle respectively according to the turning radius; Step S12: generating the first functional relationship and the second functional relationship according to the left steering wheel angle, the first rack displacement, the right steering wheel angle and the second rack displacement.

3. The steering accuracy compensation method according to claim 1, It is characterized in that In step S2, the method for judging whether the vehicle steering system meets the accuracy requirement according to the first functional relationship and the second functional relationship includes: calculate When Δs(R)=0, it indicates that the accuracy requirement is met; when Δs(R)≠0, it indicates that the accuracy requirement is not met; wherein Δs(R) is the steering deviation function under the turning radius, s g is the rack displacement in the first functional relationship, s d is the rack displacement in the second functional relationship; A c is the first distance between the steering wheel and the rack, which is calculated as Wherein, K is the wheelbase of the vehicle steering system, l 3 is the length of the rack; l 1 is the length of the first connecting rod, α g is the actual turning angle of the left steering wheel, α d is the actual turning angle of the right steering wheel, l 2 is the length of the second connecting rod, and d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel.

4. The steering accuracy compensation method according to claim 1, It is characterized in that In step S3, the method for generating the steering deviation is: Among them, D 偏差 is the steering deviation, L is the wheelbase of the vehicle steering system, K is the track width of the vehicle steering system, β g is the actual turning angle of the left steering wheel, β d is the actual turning angle of the right steering wheel.

5. The steering accuracy compensation method according to claim 1, It is characterized in that In step S4, the method for performing accuracy compensation according to the steering deviation includes: A maximum permissible deviation is generated according to the steering deviation, and then a linkage geometry parameter of the vehicle steering system is adjusted according to the maximum permissible deviation.

6. The steering accuracy compensation method according to claim 1, It is characterized in that In step S4, the method for performing accuracy compensation according to the steering deviation includes: A compensation input value is generated according to the steering deviation, and then the vehicle steering system is controlled using the compensation input value to achieve the turning radius.

7. The steering accuracy compensation method according to claim 6, It is characterized in that The method for generating the compensation input value comprises: Among them, R 实际 is the compensation input value, R is the turning radius, L is the wheelbase of the vehicle steering system, K is the track width of the vehicle steering system, β g is the actual turning angle of the left steering wheel, β d is the actual turning angle of the right steering wheel.

8. The steering accuracy compensation method according to claim 2, It is characterized in that The first functional relationship includes: Among them, β g is the actual turning angle of the left steering wheel, L is the wheelbase of the vehicle steering system, K is the wheelbase of the vehicle steering system, d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel, l 1 is the length of the first connecting rod, l 2 is the length of the second connecting rod, l 3 is the length of the rack, and s is the displacement of the rack.

9. The steering accuracy compensation method according to claim 2, It is characterized in that The second functional relationship includes: Among them, β d is the actual turning angle of the right steering wheel, L is the wheelbase of the vehicle steering system, K is the wheelbase of the vehicle steering system, d is the distance between the rack and the line connecting the left steering wheel and the right steering wheel, l 1 is the length of the first connecting rod, l 2 is the length of the second connecting rod, l 3 is the length of the rack, and s is the displacement of the rack.

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