Optimization design method and device for steering transmission mechanism of four-wheel-drive motor caravan and medium

Abstract

The invention provides an optimization design method and device for a steering transmission mechanism of a four-wheel-drive motor caravan and a medium, and belongs to the technical field of whole vehicle steering design. Whole vehicle design parameters are input, a steering system motion model is established, steering characteristics are verified based on the Ackerman theory, steering trapezium parameters are optimized, and hard point parameter initial positioning is carried out; hard point parameters are adjusted through suspension-steering coordination simulation, the transmission ratio and the number of turns of a steering wheel are optimized, and finally optimized parameters are verified and output. By establishing a quantitative evaluation system, steering performance indexes are embodied into measurable parameters such as a flat jump interference parameter a less than or equal to 0.2 and a braking deviation parameter b less than or equal to 0.5, and the design target is clarified. Parameter transmission and iteration verification are adopted, and mutual coordination of steering trapezium optimization, hard point positioning and transmission performance optimization is ensured. The design success rate and the vehicle steering performance are improved by comprehensively evaluating the motion characteristics, coordination and transmission performance of the steering system in the initial stage of design.

Description

Technical Field

[0001] This invention belongs to the field of vehicle steering design technology, specifically relating to an optimized design method, equipment, and medium for the steering transmission mechanism of a four-wheel drive motorhome. Background Technology

[0002] With the continuous improvement of residents' living standards, more and more travelers are choosing self-driving tours, making Class C motorhomes, which are modified from light truck chassis, the top choice for travel enthusiasts. To meet user needs, improve user comfort, and enhance product competitiveness, a new four-wheel drive off-road motorhome has been developed.

[0003] When designing the steering system of a four-wheel drive motorhome, parameters such as the length of the trapezoidal arm and the bottom angle are set without being specifically optimized for the overall vehicle conditions. This lack of matching steering trapezoidal parameters causes the relationship between the inner and outer wheel angles to deviate from the ideal state during steering. This makes the tires prone to slipping and wear. Long-term driving of a four-wheel drive motorhome will reduce tire life and also affect steering flexibility.

[0004] In the past, braking load and steering system motion were designed independently. The hard point parameters were not designed with the stress deformation during braking in mind. This can easily cause abnormal lateral displacement of the steering wheel and deviation of the vehicle's trajectory during braking, increasing driving safety hazards. Summary of the Invention

[0005] This invention provides an optimized design method for the steering transmission mechanism of a four-wheel drive motorhome. The method uses evaluation values ​​to evaluate various steering parameters, with clear objectives and a well-organized approach. It comprehensively considers steering performance to obtain the optimal steering parameters and guide the design of the steering system.

[0006] The methods include; S101: Input the design parameters for the four-wheel drive motorhome; S102: Based on the input design parameters of the four-wheel drive motorhome, establish a motion model of the steering system and define the spatial layout and connection relationship of the steering wheel, steering column, steering gear, rocker arm, steering tie rod and ball joint. S103: Based on Ackermann's angle theory, the relationship between the inner and outer steering wheel angles is analyzed using a steering system motion model to verify whether the steering characteristics of the steering trapezoidal mechanism meet the theoretical requirements. S104: Based on the steering characteristic analysis results, optimize the steering trapezoidal parameters and generate the optimized steering trapezoidal parameters; S105: Based on the optimized steering trapezoidal parameters, perform initial positioning of the hard point parameters of the steering system, and determine the coordinates of the rocker arm point, the knuckle point, the left ball pin point of the tie rod, and the right ball pin point of the tie rod. S106: Using the initial positioning of the steering system hardpoint parameters, perform a simulation analysis of the suspension-steering motion coordination to obtain the level jump interference evaluation parameter a and the braking deviation evaluation parameter b, and adjust the hardpoint parameters to satisfy a≤0.2 and b≤0.5; S107: Based on the adjusted hardpoint parameters of the steering system, drive the steering transmission system model, optimize the transmission ratio and the number of left and right turns of the steering wheel, obtain the transmission ratio evaluation parameter △c, the number of steering wheel turns evaluation parameter △n, and the turning radius evaluation parameter △R, and make the parameters conform to the target range; S108: Combining steering trapezoidal parameters, steering system hard point parameters, and transmission performance parameters, verify whether the overall design of the steering transmission mechanism meets the design objectives, and output the final optimized parameters.

[0007] According to another embodiment of this application, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the optimized design method for the steering transmission mechanism of the four-wheel drive motorhome.

[0008] According to another embodiment of this application, a storage medium is also provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the optimized design method for the steering transmission mechanism of the four-wheel drive motorhome.

[0009] As can be seen from the above technical solutions, the present invention has the following advantages: The optimized design method for the steering transmission mechanism of a four-wheel drive motorhome provided by this invention achieves steering characteristics that highly align with Ackermann theory. At an inner turning angle of 15°, the difference between the actual and ideal outer turning angle is controlled within 0.3°, resulting in more stable pure rolling tires during steering and reducing abnormal wear during driving. The design optimizes the side-step interference evaluation parameter a≤0.2 and the braking deviation evaluation parameter b≤0.5, eliminating the risk of motion interference between the steering system and components such as the frame, front axle, and leaf springs, leading to a smoother vehicle trajectory during braking. The transmission ratio evaluation parameter Δc is within the range of [-0.5, 1.5], the difference in the number of left and right steering wheel rotations |nl-nr|≤0.2, and the turning radius deviation |R-Rm|≤0.5, ensuring ergonomic steering operation and improved driving convenience. The hard point parameters have undergone multiple rounds of simulation verification and adjustment, ensuring coordinate accuracy meets assembly requirements and reducing installation misalignment issues in actual production. The parameters such as steering trapezoidal characteristics, suspension-steering coordination, and transmission performance are quantified and controlled to form a parameter system, providing technical support for the reliable design of the steering transmission mechanism of four-wheel drive motorhomes. Attached Figure Description

[0010] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 Flowchart of the optimized design method for the steering transmission mechanism of a four-wheel drive motorhome; Figure 2 This is a schematic diagram of the motion model of the steering system; Figure 3 A schematic diagram showing the relationship between the inner and outer corners before optimization; Figure 4 This is a schematic diagram showing the optimized relationship between the inner and outer corners; Figure 5 A schematic diagram of the Ackermann angle relationship; Figure 6 A schematic diagram illustrating an example of an Ackermann turn relationship; Figure 7 This is a schematic diagram illustrating the actual steering angle relationship when a car turns. Figure 8 This is a schematic diagram of an electronic device. Detailed Implementation

[0012] The optimization design method for the steering transmission mechanism of a four-wheel drive motorhome provided by this invention quantifies the data through steering transmission evaluation parameters, making the objectives clear. Through multiple iterative verifications, it can consider whether the steering transmission mechanism meets the design objectives in the early stages of the overall vehicle design of a four-wheel drive motorhome. It can also ensure the rationality of the steering transmission mechanism design by designers during the development of new models, and eliminate problems such as vehicle interference and transmission under actual working conditions.

[0013] The optimized design method of the steering transmission mechanism for a four-wheel drive motorhome according to this application will be described in detail below. Specific details such as particular system structures and technologies are presented for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0014] It should be understood that, when used in this specification, terms include indicating the presence of a described feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms include, encompass, have, and variations thereof mean including but not limited to, unless otherwise specifically emphasized.

[0015] The statements such as "one embodiment" or "some embodiments" described in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the statements such as "in one embodiment," "in some embodiments," "in other embodiments," and "in still other embodiments" in this application do not necessarily refer to the same embodiment, but rather mean one or more, but not all, embodiments, unless otherwise specifically emphasized.

[0016] 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.

[0017] Please see Figure 1 The diagram shows a flowchart of an optimized design method for the steering transmission mechanism of a four-wheel drive motorhome in a specific embodiment. The method includes: S101: Input the design parameters of the four-wheel drive motorhome, including the overall wheelbase, front axle track, full load weight, tire pressure, steering wheel diameter and leaf spring parameters, as the basic data for the design of the steering transmission mechanism.

[0018] In some embodiments, operating parameters are collected based on the design conditions of a light-duty truck for a four-wheel drive recreational vehicle.

[0019] In this embodiment, the vehicle wheelbase is related to the basic geometric dimensions of the steering trapezoid, and the front axle track determines the design length range of the tie rod. Full load weight affects the force distribution of the steering system, and tire pressure is related to the contact patch and steering resistance. The steering wheel diameter must match the driver's operating space, and the leaf spring parameters clearly define the space clearance requirements between the steering system and the suspension.

[0020] S102: Based on the input design parameters of the four-wheel drive motorhome, establish a motion model of the steering system and define the spatial layout and connection relationship of the steering wheel, steering column, steering gear, rocker arm, steering tie rod and ball joint.

[0021] S102 specifically includes the following steps: S1021: With the center of symmetry at the front end of the chassis as the origin, the longitudinal direction of the chassis is the X-axis, the transverse direction is the Y-axis, and the vertical direction is the Z-axis; using the centerline of the front axle as a reference, establish a local coordinate system in the steering trapezoidal area to determine the initial projection positions of the left ball joint point C and the right ball joint point D of the tie rod, as follows: Figure 5 and Figure 6 The geometric relationship between the front axle length K and wheelbase L in the Ackermann steering angle diagram is used to initially determine the theoretical range of the inner and outer wheel steering angles using the following formula.

[0022] Formula (1) In some embodiments, the parameters involved may be operating condition parameters input in S101, or parameters predetermined based on operating condition parameters.

[0023] The extensions of the axles of the two front steering wheels intersect on the extension of the rear axle. Each wheel moves in a circle around the same instantaneous steering center O, and each wheel is in a state of pure rolling. θ i θ o These are the turning angles of the inner and outer steering wheels, respectively. The spatial positioning of the components is achieved through a unified coordinate system. Formula (1) provides the geometric constraints of the turning angles under Ackermann theory, providing a basis for setting the initial parameters of the model.

[0024] S1022: Based on Figure 2 The motion model of the steering system is created by sequentially building solid models of the steering wheel 1, steering column 2, and steering gear 3. The steering gear output shaft is connected to the rocker arm 4 via a key. The steering tie rod 5 has ball joint interfaces at both ends, one end connecting to the output end of the rocker arm 4, and the other end having a reserved connection structure to the ball joint 6. Figure 7 As shown, the tie rod is equipped with left ball pin points CC10, C20, C30 and right ball pin points DD10, D20, D30. The ball head 6 and the steering tie rod 5 and the tie rod ball pin points are all designed to be rotatably connected.

[0025] In some embodiments, the steering wheel 1 is created as a cylindrical solid using Creo software, with a diameter equal to the input steering wheel diameter D; the steering column 2 is set as a hollow circular tube, with a length matching the height from the cab floor to the steering gear. The steering gear 3 is modeled as a rack and pinion structure, with a keyway at the end of the output shaft.

[0026] The rocker arm 4 is an L-shaped plate with a hole at one end to fit into the keyway of the steering gear output shaft, and a ball joint seat at the other end; the steering tie rod 5 is an adjustable length rod with ball joint holes at both ends matching the outer diameter of the rocker arm ball joint seat and the ball head 6; the horizontal tie rod is equipped with left ball pin points CC10, C20, C30 and right ball pin points DD10, D20, D30.

[0027] S1023: The steering column 2 and the input shaft of the steering gear 3 are set as a coaxial rotary joint; the rocker arm 4 and the output shaft of the steering gear 3 are set as a rigid connection; the steering tie rod 5, rocker arm 4, and ball joint 6 are set as a spherical joint; the tie rod and ball joint 6 are set as a spherical joint, the distance between the two ball pin points C and D of the tie rod is set according to the initial value of the trapezoidal arm length m, and the trapezoidal base angle γ is set according to... Figure 7 Preliminary assignment of geometric angles; The actual inner wheel rotation angle θ of the initial trapezoid is calculated based on the following formula. si , compared with the ideal angle of formula (1).

[0028] Formula (2) In some embodiments, in the Creo assembly module, a coaxial relative rotation constraint is added between the steering column 2 and the input shaft of the steering gear 3. A rigid connection constraint is added between the rocker arm 4 and the output shaft of the steering gear 3. Spherical joint constraints are added between the ball joint holes at both ends of the steering tie rod 5 and the ball joint seat and ball head 6 of the rocker arm 4, respectively. The distance between the two ball pin points C and D of the tie rod is set as the initial trapezoidal arm length m, and the angle between the tie rod and the frame is set as the trapezoidal base angle γ. Substituting γ=70°, m=200mm, K=1500mm, θo=10° into formula (2), θ is calculated. si And θ obtained from Formula 1 i Comparison. The steering trapezoidal kinematics are realistically reproduced, and the steering angle deviation under initial parameters is quantified.

[0029] S1024: Import the steering system model into the vehicle assembly model. Using the front mounting surface of the frame and the cab floor crossbeam as positioning references, constrain the connection point between the lower end of the steering column 2 and the frame, and the fixing point between the steering gear 3 housing and the frame. Check the spatial clearance between the steering system components and the front longitudinal beam of the frame, the cab floor wiring harness bracket, and the front axle steering knuckle, and record the initial interference points.

[0030] In some embodiments, using a preset mounting point on the front longitudinal beam of the chassis as a reference, the lower bolt hole of the steering column 2 is constrained to coincide with the chassis connection point, and the mounting lug of the steering gear 3 housing is coaxial with the crossbeam hole of the chassis. The steering wheel 1 is manually rotated, and the gaps between the steering tie rod 5, the tie rod and the chassis longitudinal beam, and the cab floor wiring harness bracket are observed. The minimum gap value and the coordinates of the interference points are recorded. By assembling the entire vehicle, static interference between components is exposed, the rationality of the layout is verified, and layout conflicts between the steering system and surrounding components are detected in advance.

[0031] S103: Based on Ackermann's angle theory, the relationship between the inner and outer steering wheel angles is analyzed using a steering system motion model to verify whether the steering characteristics of the steering trapezoidal mechanism meet the theoretical requirements.

[0032] S103 specifically includes the following steps: S1031: Determine the steering angle θ of the inner and outer steering wheels i θ o Ideal geometric relations, combined with As a theoretical verification benchmark, K is the front axle length, which is the projected length of the distance between the centers of the two front wheels in the longitudinal direction of the frame, and L is the wheelbase of the whole vehicle.

[0033] In some embodiments, combined with Figure 5 and Figure 6A schematic diagram of the Ackermann steering angle relationship shows that the extended lines of the two front wheel axles intersect the instantaneous steering center O on the extended line of the rear axle. The steering angle θi of the inner wheel is less than the steering angle θo of the outer wheel. According to formula (1), take K as the distance between the two ball pin points C and D of the front axle in the longitudinal direction of the frame, and L as the wheelbase of the vehicle. Substitute θo=10°, K=1500mm, L=3500mm, The calculated cotθi = cot10° - 1500 / 3500 ≈ 5.671 - 0.429 = 5.242, corresponding to θi ≈ 10.8°, which serves as the theoretical benchmark.

[0034] S1032: Based on the motion model of the steering system established in S102, the trapezoidal arm length m, trapezoidal base angle γ, and the distance between the left ball pin point C and the right ball pin point D of the front axle tie rod of the current steering trapezoidal mechanism are collected, i.e., the front axle length K. The outer wheel rotation angle θ in the model is recorded. o The preset range of variation can be, for example, 5° to 25°.

[0035] In some embodiments, in the Creo steering system motion model established in S102, the length m of the trapezoidal arm is obtained using a measuring tool, which is the distance from the tie rod ball pin points C and D to the steering knuckle arm. The base angle γ of the trapezoid is measured using a protractor, which is the angle between the tie rod and the steering knuckle arm. The driving range of the outer wheel rotation angle θo in the model is read, such as 5°, 10°, 15°, 20°, and 25° set via a servo motor. Here, actual structural parameters are extracted from the established model to reflect the current physical state of the steering trapezoid.

[0036] like Figure 3 and Figure 4 As shown, the steering trapezoidal mechanism optimized using Matlab exhibits good agreement between the actual inner wheel rotation angle and the ideal inner wheel rotation angle within the range of 0~15° of the outer rotation angle, meeting the design requirements.

[0037] S1033: θ set for S1032 o Change value, using Calculate the actual inner wheel rotation angle θ si The values ​​of m, γ, and K collected from the model are substituted into the calculations one by one.

[0038] In some embodiments, θ is taken o =10°, substitute the m=200mm, γ=70°, K=1500mm collected by S1032 into formula (2).

[0039] This embodiment calculates the terms within the denominator under the square root sign: (1500 / 200)²+1-2(1500 / 200)cos(70°+10°)=56.25+1-15cos80°≈57.25-15*0.174≈54.64, √(7.39).

[0040] The molecule's sin(70° + 10°) = sin80° ≈ 0.985. The first term is arcsin(0.985 / 7.39)≈arcsin0.133≈7.6°.

[0041] Second molecule (1500 / 200)[2cos70°-cos80°-cos140°]=7.5(2*0.342-0.174-(-0.766))=7.5*(0.684-0.174+0.766)=7.5*1.276≈9.57, divided by 7.39≈1.296, arccos1.296 exceeds the domain, indicating that the parameter needs to be adjusted. After recalculating with a reasonable value, θ is obtained. si .

[0042] S1034: According to , from θ of S1032 o The ideal inner wheel rotation angle θ can be derived from the given wheelbase L and the value. i ; Outer wheel rotation angle θ o Plot the theoretical characteristic curve and the actual characteristic curve with the horizontal axis as the horizontal axis and the inner wheel rotation angle as the vertical axis.

[0043] In some embodiments, for θ of S1032 o =10°, using formula (1) cot10°-cotθ i =1500 / 3500, so cotθi≈5.671-0.429=5.242, θ i ≈10.8°, taken as the ideal value. θ calculated using S1033 si Comparing θi, plot points (10°, 10.8°) and (10°, 11.2°) in the coordinate system, repeating θo = 15°, 20°, etc., to draw two curves. In this way, the deviation between the actual rotation angle and the theoretical rotation angle can be visually displayed through graphical comparison.

[0044] S1035: When the inner steering angle θi is 15°, determine whether the difference between the actual value and the theoretical value of the outer steering angle θo is ≤0.3°. If the relative deviation trends of θsi and θi are consistent across all θo ranges and the maximum difference meets the requirements, then the steering characteristics are determined to meet the theoretical requirements.

[0045] In some embodiments, θsi = 15° is set, and the actual value of θo is calculated by substituting it into formula (2). The theoretical value of θo is calculated using formula (1) from θi = 15°, where cotθ o =cot15°+1500 / 3500≈3.732+0.429=4.161, θo≈13.5°. The difference between the two is 13.5°-12.5°=1.0°. If it is greater than 0.3°, it is considered non-compliant. Check all θ o The maximum difference between θsi and θi is considered acceptable if both are ≤0.3°. Here, an inner turning angle of 15° is used as the key verification point to check the accuracy of the trapezoid under common steering angles. This ensures the steering trapezoid meets requirements under preset operating conditions, reducing abnormal tire wear.

[0046] S104: Based on the steering characteristic analysis results, optimize the steering trapezoidal parameters, including the trapezoidal arm length, trapezoidal base angle, and tie rod ball pin position, and generate the optimized steering trapezoidal parameters.

[0047] S104 specifically includes the following steps: Step S1041: Combine the front axle track S, the front end space of the frame, and the front axle structure of the vehicle to determine the constraint boundary of the steering trapezoid optimization variables, and clarify the range of values ​​for the trapezoid arm length m and the trapezoid base angle γ.

[0048] In some embodiments, referencing the front axle track S of the vehicle, setting the lower limit of the trapezoidal arm length m to S / 5 ensures the stability of the trapezoidal structure. The upper limit is set to 80% of the minimum horizontal distance between the front end of the frame and the front axle. Considering the steering tie rod's swing trajectory, the lower limit of the trapezoidal base angle γ is set to 65° to prevent self-locking of the trapezoidal mechanism. The upper limit is set to 82° to avoid collision between the tie rod and the leaf spring during steering. The constraint boundaries are initially verified using the vehicle's three-dimensional assembly model, eliminating obviously infeasible areas.

[0049] S1042: Based on the angle difference distribution in S103, define the weighting factor ω. o (θ o The design objective function f(x) for evaluating the steering trapezoid is constructed using formulas (3) and (4), with the goal of minimizing the deviation between the actual and ideal steering angles. Formula (3) Formula (4) In some embodiments, a weighting factor ω is set for the commonly used steering range of 5°-25° for the outer wheel steering angle. o (θ o The value is set to 0.8-1.0, for the less common ranges of 0°-5° and 25° to the maximum turning angle. o (θ o The value is 0.2-0.5.

[0050] In this embodiment, the weight distribution is adjusted according to the following formula: Formula (3) Formula (4) Where k is the weight gradient coefficient k=0.8, and θo is the reference value of the rotation angle.

[0051] S1043: Establish geometrical constraints for the optimization variables, relating the trapezoidal arm length m, base angle γ, and the spatial position of the tie rod ball pin to ensure the minimum installation clearance with the front axle suspension components.

[0052] In some embodiments, geometric association constraints are established, and the length m of the trapezoidal arm must satisfy m≥2d, where d is the diameter of the ball joint connection part, to ensure connection strength. The base angle γ of the trapezoid satisfies the domain requirements of the arcsin and arccos functions in formula (2). The minimum spatial clearance between the tie rod ball pin point and the front axle suspension is ≥8mm, constrained by the distance formula between the ball pin point coordinates and the suspension component coordinates.

[0053] S1044: Select m0 and γ0 of the initial turning trapezoid as the initial values ​​for optimization, call the constraint optimization algorithm, input the objective function, constraint boundary and geometric association conditions, and iteratively solve for the optimal parameters.

[0054] In some embodiments, the arm length m0 (S / 3) and base angle γ0 (75°) of the initial turning trapezoid are used as the initial optimization values, and the iteration accuracy of the constraint optimization algorithm is set to 1×10⁻⁶. -5 The maximum number of iterations is 300.

[0055] In this embodiment, the constraint boundary of step S1041, the objective function of step S1042, and the geometric association conditions of step S1043 are input into the algorithm. Through iterative calculation, m and γ are gradually adjusted until the objective function value converges to the minimum value, and the optimal m and γ are output.

[0056] S1045: Substitute the optimal m and γ into formula (2) to calculate the actual rotation angle θsi, verify the difference with the ideal θi, check the spatial interference between the tie rod ball pin position and the front axle and leaf spring, and generate the final optimized parameters.

[0057] In some embodiments, the optimal m and γ are substituted into the following formula: Formula (2) Calculate the actual rotation angle θsi across the entire rotation range and verify that |θsi-θi|≤0.3° when the internal rotation angle is 15°.

[0058] In this embodiment, the coordinates of the tie rod ball joint point corresponding to the optimal parameters are imported into the three-dimensional model of the vehicle. The spatial distances with the front axle and leaf springs are verified to ensure no interference, thus forming a complete set of optimized parameters including m, γ, and the ball joint point coordinates. In this way, the cornering characteristics are verified through formula (2) to ensure that the optimized parameters meet the theoretical requirements, and the three-dimensional model verification eliminates the risk of spatial interference.

[0059] S105: Based on the optimized steering trapezoidal parameters, perform initial positioning of the hard point parameters of the steering system, and determine the coordinates of the rocker arm point, the knuckle arm point, the left ball pin point of the tie rod, and the right ball pin point of the tie rod.

[0060] In some embodiments, the hardpoint parameter is the reference for the installation of steering system components. The coordinates of the hardpoint parameter are derived from the steering trapezoid optimization results to ensure that the connection relationship of each component matches the motion trajectory.

[0061] Optionally, initial positioning of the hard point parameters of the steering system can include rocker arm point A (A10, A20, A30), knuckle arm point B (B10, B20, B30), tie rod left ball pin point C (C10, C20, C30), and tie rod right ball pin point D (D10, D20, D30), thereby determining whether rocker arm point A and knuckle arm point B meet the requirements.

[0062] S106: Using the initial positioning of the steering system hardpoint parameters, perform a simulation analysis of the suspension-steering motion coordination to obtain the level jump interference evaluation parameter a and the braking deviation evaluation parameter b, and adjust the hardpoint parameters to satisfy a≤0.2 and b≤0.5.

[0063] In some embodiments, the hard point coordinates are imported into multibody dynamics software to build a suspension-steering coupling model, and leaf spring elastic constraints and tire contact constraints are added.

[0064] In this embodiment, a flat jump condition is set up, and the minimum spatial clearance between the steering component and the frame and front axle is collected. The interference parameters are calculated according to a = (safe clearance threshold - simulated minimum clearance) / safe clearance threshold.

[0065] Set the braking conditions, collect the lateral displacement of the steering wheel, and calculate the deviation parameters according to b = peak value of braking lateral displacement / front axle track S.

[0066] If a > 0.2, fine-tune the Z-coordinate of the ball joint; if b > 0.5, symmetrically adjust the Y-coordinates of the left and right joints, and repeat the simulation until the parameters meet the standards. This eliminates motion interference between the steering system and surrounding components, and controls the deviation during braking.

[0067] S107: Based on the adjusted hardpoint parameters of the steering system, drive the steering transmission system model, optimize the transmission ratio and the number of left and right turns of the steering wheel, obtain the transmission ratio evaluation parameter △c, the number of steering wheel turns evaluation parameter △n, and the turning radius evaluation parameter △R, and make the parameters conform to the target range.

[0068] S108: Combining steering trapezoidal parameters, steering system hard point parameters, and transmission performance parameters, verify whether the overall design of the steering transmission mechanism meets the design objectives, and output the final optimized parameters.

[0069] In some embodiments, all parameters are integrated to form a structured dataset, which is classified into geometric parameters, performance parameters, and transmission parameters, and the source and constraints of each parameter are labeled.

[0070] Each parameter of the steering trapezoidal angle difference (a, b, Δc, Δn, ΔR) was verified to ensure compliance with standards. A vehicle-level coupled model was built to simulate steering, braking, and level jump conditions, verifying performance under boundary conditions such as maximum steering angle, extreme braking, and full-load / no-load switching. Finally, parameter documents were compiled according to the vehicle design specifications, clarifying coordinate references, assembly tolerances, and installation requirements, and including parameter correlation diagrams. This ensured that all performance indicators of the steering transmission mechanism met design requirements.

[0071] In one embodiment of the present invention, based on step S105, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S105 specifically includes the following steps: S1051: Establish the vehicle coordinate system and determine the reference plane of the front axle centerline and the spatial equation of the kingpin axis.

[0072] In some embodiments, a right-handed coordinate system is established with the vehicle's longitudinal center plane as the XZ plane and the front axle centerline as the Y-axis reference. According to... The geometric parameters are used to determine the equation of the spatial straight line corresponding to the kingpin inclination angle. The angle between the projection of the kingpin axis on the XZ plane and the Z-axis is equal to the kingpin inclination angle.

[0073] S1052: Based on the optimized trapezoidal arm length m and base angle γ, calculate the spatial position of each hard point of the turning trapezoid relative to the kingpin axis.

[0074] In some embodiments, the optimized trapezoidal arm length m and base angle γ are substituted into the geometric relationship of formula (2) to calculate the coordinates of the left and right ball pin points C and D of the tie rod relative to the main pin ground point. During the calculation process, the influence of the arccot ​​term in formula (4) on the longitudinal position of the ball pin point is considered to ensure the motion continuity of the trapezoidal mechanism during the turning process.

[0075] S1053: Determine the initial installation positions of rocker arm point A and sling arm point B based on the motion characteristics of the steering gear output end.

[0076] In some embodiments, the initial position of rocker arm point A is determined based on the correspondence between the rack travel at the steering gear output end and the rocker arm swing angle.

[0077] Here, the spatial relative position of the joint arm point B and the rocker arm point A is calculated by using the γ angle constraint in formula (2) to ensure that the steering tie rod is perpendicular to the rocker arm when in the straight driving position.

[0078] S1054: Check the interference between the movement trajectory of the left and right ball joints of the tie rod and the movement of the suspension.

[0079] In some embodiments, the coordinates of the left and right ball pin points C and D of the tie rod are substituted into formula (2) to calculate the motion trajectory of the ball pin points when the wheel turns at different angles. The gap between the ball pin point trajectory and the suspension motion envelope is checked by the error evaluation method of formula (3) to ensure that there is no motion interference.

[0080] S1055: Outputs the three-dimensional coordinates of each hard point in the vehicle coordinate system.

[0081] In some embodiments, the three-dimensional coordinates of rocker arm point A (A10,A20,A30), joint arm point B (B10,B20,B30), tie rod left ball joint point C (C10,C20,C30), and right ball joint point D (D10,D20,D30) are output in the vehicle coordinate system. The coordinate values ​​of each point are verified by the geometric relationship in formula (2) to ensure that the Ackermann steering principle is satisfied.

[0082] In one embodiment of the present invention, based on step S106, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S106 specifically includes the following steps: S1061: Import the initial positioning steering system hard point coordinates, leaf spring assembly parameters, unsprung mass and wheelbase data, and integrate them into the basic dataset for suspension steering motion simulation.

[0083] In some embodiments, the three-dimensional coordinates of rocker arm point A, hinge point B, and tie rod ball pin point C / D determined in step S105 are extracted, and the leaf spring free arc height, assembly angle, unsprung mass value, and vehicle wheelbase L mentioned in the initial technical solution are supplemented. These are then organized into a unified dataset according to the simulation software data format. The units of each parameter are clearly defined in the dataset to ensure that the hard point coordinates are consistent with the installation reference of the leaf spring and front axle, and match the steering system motion model parameters established in step S102.

[0084] S1062: Build a multibody dynamics simulation model, add leaf spring elastic constraints, tire ground contact constraints and steering system kinematic pairs, and associate hard point parameters with vehicle structural components.

[0085] In some embodiments, the processed dataset is imported into the multibody dynamics simulation software to create simulation entities of the frame, front axle, leaf spring, and steering system components.

[0086] Nonlinear elastic constraints are added to the leaf springs, and vertical load-ground area correlation constraints are added to the tires. The length m and bottom angle γ of the steering trapezoidal arm are correlated, and the consistency between the steering motion and Ackermann theory is ensured through formula (1), thus constructing a suspension-steering coupling simulation model.

[0087] S1063: Set the horizontal jump simulation condition and the braking simulation condition, and define the simulation output parameter type.

[0088] In some embodiments, the horizontal jump simulation condition sets the suspension to jump up and down along the Z-axis, with a single jump cycle of 1 second, and runs continuously for 5 cycles. The minimum space clearance between the steering tie rod, rocker arm, front end of the frame, and cab floor is collected in each cycle. The braking simulation condition sets the vehicle to decelerate with a constant acceleration of 0.6g for 3 seconds, and collects data on the lateral displacement of the steering wheel and the braking force distribution between the left and right front wheels during braking. The simulation output parameters are set as three types of raw data: minimum clearance value, peak lateral displacement value, and braking force difference value.

[0089] S1064: Run the simulation model, collect spatial clearance data between the steering components and the frame and front axle, as well as lateral displacement data during braking, and calculate the horizontal bounce interference evaluation parameter a and the braking deviation evaluation parameter b.

[0090] In some embodiments, the evaluation parameter a for the horizontal jump interference is calculated as a = (safety gap threshold - simulated minimum gap) / safety gap threshold.

[0091] The safety gap threshold is set to 10mm. When the minimum simulated gap is ≥10mm, a=0. The smaller the gap, the larger the value of a.

[0092] The braking deviation evaluation parameter b is calculated as b = peak braking lateral displacement / front axle track S, and the peak lateral displacement is directly extracted from the simulation data.

[0093] During the calculation process, formula (2) is used to verify whether the steering angle is offset due to the braking load, and to ensure that the b value only reflects the running characteristics rather than the steering angle deviation.

[0094] S1065: If a > 0.2 or b > 0.5, locally fine-tune the Z or Y coordinates of the hard point, repeat the simulation until the parameters meet the threshold requirements, and finally obtain the hard point parameters.

[0095] In some embodiments, if a > 0.2, adjust the Z coordinate of the ball pin point C / D of the horizontal tie rod, with each adjustment amount ≤ 2mm, and adjust the direction along the vertical direction away from the interference component.

[0096] If b > 0.5, the Y coordinate of the fine adjustment arm point B and the adjustment amount of the left and right arm points are symmetrical to avoid disrupting the symmetrical structure of the steering trapezoid.

[0097] After each adjustment, the simulation is rerun until a≤0.2 and b≤0.5. During the adjustment process, the length m of the trapezoidal arm, the base angle γ, and the X coordinate of the hard point must remain unchanged to ensure that the optimized steering characteristics are not affected.

[0098] In one embodiment of the present invention, based on step S107, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S107 specifically includes the following steps: S1071: Define the target parameters of the steering transmission system, and determine the target transmission ratio cm, the target number of left and right turns of the steering wheel nm, and the target turning radius Rm.

[0099] In some embodiments, the target transmission ratio is determined by combining the vehicle wheelbase L, front axle track S, and maximum outer wheel turning angle θomax, according to cm = (maximum design turning angle of steering wheel × transmission efficiency) / θomax. Optionally, the transmission efficiency is taken as 0.95.

[0100] Based on the minimum turning radius design requirement of the vehicle, Rm can be set, and the target value nm for the number of steering wheel turns to the left and right can be set to 2.5 turns each. The target parameters match the vehicle design operating parameters in step S101.

[0101] S1072: Import the adjusted hardpoint parameters of the steering system, associate the transmission components such as the steering gear, rocker arm, and steering tie rod, and build a simulation model of the steering transmission system.

[0102] In some embodiments, the three-dimensional coordinates of rocker arm point A, joint arm point B, and tie rod ball pin point C / D from step S106 are extracted, imported into simulation software, and associated with the transmission interfaces of the steering gear input shaft and steering wheel, and output shaft and rocker arm.

[0103] In this embodiment, the connection position between the steering gear and the rocker arm is adjusted according to the hard point coordinates to ensure that the rocker arm swing trajectory matches the motion trajectory of the steering tie rod. Adjustable parameters of the internal gear transmission ratio of the steering gear are configured to build a complete simulation model of the steering transmission system.

[0104] S1073: Define the optimized variables, steering gear ratio i and rocker arm effective length La, and set constraints including parameter value ranges and adaptation requirements with Ackermann angle.

[0105] In some embodiments, the optimization variables are set as steering gear ratio i and rocker arm effective length La.

[0106] Optionally, the steering gear ratio i ranges from 16 to 22, determined based on the steering wheel diameter D and the driver's operating force threshold. The effective rocker arm length La ranges from the rocker arm length determined in step S105 to ±5mm, avoiding exceeding the hard point space constraint.

[0107] The constraints include: i×La fitting formula The Ackermann steering angle relationship ensures that the inner and outer wheel steering angles match during steering. La is not less than the minimum length required for the ball joint connection strength.

[0108] S1074: Run the simulation model for iterative optimization, collect the actual transmission ratio c, the number of left and right turns of the steering wheel nl / nr, and the actual turning radius R, and calculate Δc, Δn, and ΔR.

[0109] In some embodiments, the simulation iteration step size is set to 0.1. In each iteration, the values ​​of i and La are adjusted by a preset magnitude to drive the steering wheel from the left limit position to the right limit position. The number of right turns nl and the number of left turns nr are collected, and Δn=|nl-nr| is calculated.

[0110] In this embodiment, the ratio of the steering wheel rotation angle to the front wheel rotation angle is obtained through simulation, the actual transmission ratio c is obtained, and Δc = c - cm is calculated.

[0111] Combination The derived formula for calculating the turning radius is R=L / cotθo-S / 2. The actual turning radius R output from the simulation is extracted, and ΔR=R-Rm is calculated.

[0112] S1075: Verify whether the evaluation parameters meet the threshold requirements. If they do not meet the requirements, fine-tune the optimization variables and repeat the simulation. Once the requirements are met, lock the final transmission parameters.

[0113] In some embodiments, it is verified whether Δc is in the interval [-0.5, 1.5], whether Δn is ≤0.2, and whether ΔR is in the interval [-0.5, 0.5].

[0114] If the target is not met, fine-tune the optimization variables by increments of ±0.1 mm for i and ±1 mm for La, then rerun the simulation to collect data and calculate the evaluation parameters.

[0115] Until all parameters meet the threshold requirements, the final steering gear ratio i, rocker arm effective length La, and corresponding Δc, Δn, and ΔR are recorded to form a complete transmission parameter set. This fine-tuning targets and corrects local parameter deviations, and multiple simulations verify that all performance indicators meet the standards.

[0116] In one embodiment of the present invention, based on step S108, the following is a possible embodiment and its specific implementation will be described in a non-limiting manner. S108 specifically includes the following steps: S1081: Integrate steering trapezoidal parameters, steering system hard point parameters, and transmission performance parameters to establish a unified parameter dataset and label the source and constraints of each parameter.

[0117] In some embodiments, the optimized trapezoidal arm length m, base angle γ, and tie rod ball pin coordinates of step S104 are extracted, the rocker arm point A and joint arm point B coordinates are locked in step S106, and the steering gear transmission ratio i, rocker arm effective length La, and Δc, Δn, and ΔR are determined in step S107.

[0118] The parameters will be categorized, each parameter will be labeled with the corresponding preceding step number, and the coordinate reference, units, etc. will be standardized to form a dataset.

[0119] S1082: Verify the compliance of parameters according to the design objectives, including steering trapezoidal angle difference, horizontal jump interference a, braking deviation b, and transmission evaluation parameters △c, △n, and △R.

[0120] In some embodiments, when verifying the steering trapezoidal parameters, m and γ are substituted into formula (2) to calculate the actual turning angle θsi, and formula (1) is used to verify that when the inner turning angle is 15°, |θsi-θi|≤0.3°.

[0121] In this embodiment, the horizontal jump interference a is checked to see if it is ≤0.2 according to the calculation method of S1064, and the braking deviation b is checked to see if it is ≤0.5.

[0122] Verify the transmission parameters: whether Δc is within [-0.5, 1.5], whether Δn is ≤0.2, and whether ΔR is within [-0.5, 0.5]. Record the verification results for each parameter and mark the deviation values ​​of parameters that do not meet the standards.

[0123] S1083: Build a vehicle-level steering transmission coupling simulation model, link the steering system with the suspension and braking system, and simulate the collaborative working state under combined working conditions.

[0124] In some embodiments, the integrated parameter dataset is imported into the vehicle assembly model to associate the elastic constraints of the steering system and the front axle leaf springs with the braking force transmission path of the braking system.

[0125] In this embodiment, the composite working condition is set as a combination of steering and braking, and steering and descent. The simulation output is defined as the overall performance indicators such as steering response speed, tire ground pressure distribution, and steering wheel operating force.

[0126] The performance of the steering system in this embodiment is based on its collaborative operation with other systems, and the composite operating condition simulation can reproduce real-world scenarios in actual use. This verifies the feasibility of the parameters under coupled system conditions and improves the completeness of the design.

[0127] S1084: Verify boundary conditions, including maximum steering angle, extreme braking, and full load / no load switching conditions, and collect overall performance data.

[0128] In some embodiments, the maximum steering angle is set at 35° for the outer wheel, and the steering system is monitored for interference-free operation. The extreme braking condition is set at a braking acceleration of 0.8g to verify that there is no abnormal steering wheel deviation during braking. Full-load / no-load switching conditions are simulated separately for full-load mass G and no-load mass, and the fluctuation range of steering performance parameters is compared to ensure that the fluctuation does not exceed 10% and there is no significant performance degradation.

[0129] S1085: Configure all compliant parameters, organize parameter documents according to the vehicle design specifications, clarify the installation reference and tolerance requirements of the parameters, and output the final optimization results.

[0130] In some embodiments, parameter documents are compiled according to vehicle design specifications. Geometric parameters are labeled with three-dimensional coordinates and installation references to the frame and front axle. Performance parameters are labeled with threshold ranges and measured values. Transmission parameters specify the assembly tolerances of the steering gear and rocker arm. This optimizes parameters to assist in the actual production process and reduces errors during parameter conversion.

[0131] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0132] like Figure 8 As shown, this application also provides an electronic device, including a display module 103, a memory 102, a processor 101, a communication module 104, and a computer program stored in the memory and executable on the processor 101. When the processor 101 executes the program, it implements the steps of an optimized design method for the steering transmission mechanism of a four-wheel drive motorhome.

[0133] In embodiments of the present invention, electronic devices include, but are not limited to, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments described and / or claimed herein.

[0134] In this embodiment, processor 101 may be implemented using at least one of an application-specific integrated circuit, a programmable logic device, a field-programmable gate array, a processor, a controller, a microcontroller, a microprocessor, or an electronic unit designed to perform the functions described herein. In some cases, such an implementation may be implemented within a controller. For software implementation, implementations such as processes or functions may be implemented with separate software modules that allow the performance of at least one function or operation. Software code may be implemented by a software application (or program) written in any suitable programming language, and the software code may be stored in memory and executed by the controller.

[0135] The display module 103 is used to display information input by the user or information provided to the user. The display module 103 may include a display panel, which may be configured in the form of a liquid crystal display, an organic light-emitting diode, or the like.

[0136] The memory 102 can be used to store software programs and various data. The memory 102 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0137] The communication module 104 transmits radio signals to and / or receives radio signals from at least one of a base station, an external terminal, and a server. Such radio signals may include voice call signals, video call signals, or various types of data sent and / or received according to text and / or multimedia messages.

[0138] The present invention also provides a storage medium storing a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the optimized design method for the steering transmission mechanism of the four-wheel drive motorhome.

[0139] The storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0140] The storage medium stores a program product capable of implementing the methods described above in this specification. In some possible implementations, various aspects of this disclosure can also be implemented as a program product comprising program code that, when run on a terminal device, causes the terminal device to perform the steps described in the exemplary methods section of this specification according to various exemplary embodiments of this disclosure.

[0141] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optimal design method of a four-wheel drive recreational vehicle steering transmission mechanism, characterized by, The method comprises: S101: inputting four-wheel drive recreational vehicle design working condition parameters; S102: establishing a steering system motion model based on the input four-wheel drive recreational vehicle design working condition parameters, and defining the spatial layout and connection relationship of the steering wheel, steering column, steering gear, rocker arm, steering straight pull rod and ball head; S103: based on the Ackerman angle theory, analyzing the inner and outer steering wheel angle relationship by using the steering system motion model, and verifying whether the steering trapezoidal mechanism meets the theoretical requirements; S104: optimizing the steering trapezoidal parameters according to the steering characteristic analysis result, and generating the optimized steering trapezoidal parameters; S105: based on the optimized steering trapezoidal parameters, performing initial positioning on the steering system hard point parameters, and determining the coordinates of the rocker arm point, knuckle point, left ball pin point of the tie rod and right ball pin point of the tie rod; S106: using the initial positioning steering system hard point parameters, performing suspension-steering motion coordination simulation analysis, obtaining flat jump interference evaluation parameter a and brake deviation evaluation parameter b, and adjusting the hard point parameters to meet a≤0.2 and b≤0.5; S107: based on the adjusted steering system hard point parameters, driving the steering transmission system model, optimizing the transmission ratio and the left and right turns of the steering wheel, obtaining transmission ratio evaluation parameter Δc, steering wheel turn evaluation parameter Δn and turning radius evaluation parameter ΔR, and making the parameters meet the target range; S108: verifying whether the overall design of the steering transmission mechanism meets the design target by comprehensively considering the steering trapezoidal parameters, steering system hard point parameters and transmission performance parameters, and outputting the final optimized parameters.

2. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 1, wherein, S102 specifically comprises the following steps: Taking the symmetry center of the front end of the frame as the origin, the longitudinal direction of the frame as the X axis, the transverse direction as the Y axis, and the vertical direction as the Z axis; taking the center line of the front axle as the reference, a local coordinate system is established in the steering trapezoidal area to determine the initial projection positions of the left ball pin point C and the right ball pin point D of the tie rod, the geometric relationship of the front axle length K and the wheelbase L, and the theoretical range of the inner and outer wheel angles is preliminarily set by the following formula: Equation (1) The entity models of the steering wheel (1), steering column (2) and steering gear (3) are created in sequence, the output shaft of the steering gear is connected with the rocker arm (4) through a key, the steering straight pull rod (5) is provided with spherical hinge interfaces at both ends, one end is connected with the output end of the rocker arm (4), and the other end is provided with a connection structure with the ball head (6); the tie rod is provided with the left ball pin point C (C10, C20, C30) and the right ball pin point D (D10, D20, D30), and the ball head (6) is designed to be rotatably connected with the steering straight pull rod (5) and the ball pin points of the tie rod; The steering column (2) and the input shaft of the steering gear (3) are coaxially connected; the rocker arm (4) and the output shaft of the steering gear (3) are rigidly connected; the steering straight pull rod (5) is connected with the rocker arm (4) and the ball head (6) through a spherical pair; the tie rod and the ball head (6) are connected through a spherical pair, and the distance between the two ball pin points C and D of the tie rod is set according to the initial value of the trapezoidal arm length m; The initial trapezoidal actual inner wheel rotation angle θ is calculated based on the following formula si and compared with the ideal rotation angle of formula (1); Equation (2) Import the steering system model into the vehicle assembly model, and take the front end mounting surface of the frame and the floor beam of the cab as the positioning reference. Restrain the connection point of the lower end of the steering column (2) and the frame, and the fixed point of the housing of the steering gear (3) and the frame. Check the space clearance between the steering system components and the front end longitudinal beam of the frame, the wire harness support of the cab floor, and the front axle steering knuckle. Record the initial interference parts.

3. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 1, wherein, S103 specifically includes the following steps: Determine the ideal geometric relationship of inner and outer steering wheel rotation angle θi, θo, combined with As a theoretical verification benchmark, where K is the front axle length, L is the wheelbase of the vehicle; Based on the steering system motion model established in S102, collect the length m of the trapezoidal arm, the trapezoidal base angle γ, and the distance between the left ball pin point C and the right ball pin point D of the front axle tie rod; θ set for S1032 o change value, using The actual inner rotation angle θ is calculated si The values of m, γ, and K collected by the model are substituted and calculated successively. According to The ideal inner wheel rotation angle θi is deduced from the value of θo and the known wheel base L. The theoretical characteristic curve and the actual characteristic curve are plotted with the outer wheel rotation angle θo as the horizontal axis and the inner wheel rotation angle as the vertical axis. When the inner turning angle θi is 15°, it is determined whether the difference between the actual value and the theoretical value of the outer turning angle θo is ≤0.3°, and if all θo ranges satisfy the condition that the difference between the actual value and the theoretical value of the outer turning angle θo is ≤0.3°, the turning characteristic is determined to be in conformity with the theoretical requirement. si The relative deviation trend of θ i is consistent with that of θ The maximum difference satisfies the requirement, and the turning characteristic is determined to be in conformity with the theoretical requirement.

4. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 2, wherein, S104 specifically includes the following steps: Determine the constraint boundary of the steering trapezoidal optimization variable in combination with the front axle track S of the whole vehicle, the front end space of the frame, and the front axle structure, and specify the value range of the trapezoidal arm length m and the trapezoidal base angle γ. Based on the corner difference value distribution of S103, define the weighting factor ω o (θ o ), through formula (3) and formula (4) to constitute the design objective function f(x) for evaluating the steering trapezoid, with the goal of minimizing the actual and ideal corner deviation; Equation (3) Equation (4) k is a weight gradient coefficient, θ o is a reference value of the rotation angle; Establish the geometric correlation constraint of the optimization variable, and correlate the trapezoidal arm length m, the base angle γ, and the space position of the tie rod ball pin point. Select m0 and γ0 of the initial steering trapezoid as the optimization initial value, call the constraint optimization algorithm, input the objective function, the constraint boundary, and the geometric correlation condition, and iteratively solve the optimal parameters. Substitute the optimal m and γ into formula (2) to calculate the actual rotation angle θ si , verify the difference with the ideal θ i , check the spatial interference of the cross rod ball pin point position with the front axle and leaf spring, and generate the final optimization parameters.

5. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 1, wherein, S105 specifically includes the following steps: Establish the whole vehicle coordinate system, determine the front axle center line reference plane and the spatial equation of the kingpin axis, and collect the length m of the trapezoidal arm, the trapezoidal base angle γ, and the distance between the left ball pin point C and the right ball pin point D of the front axle tie rod. Based on the optimized trapezoidal arm length m and base angle γ, calculate the spatial position of each hard point of the steering trapezoid relative to the kingpin axis. Determine the initial installation position of the rocker arm point A and the knuckle arm point B according to the motion characteristics of the steering gear output end. Check the interference between the motion trajectory of the left and right ball pin points of the tie rod and the suspension motion. Output the three-dimensional coordinate values of each hard point in the whole vehicle coordinate system.

6. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 1, wherein, S106 specifically includes the following steps: Import the initially positioned steering system hard point coordinates, the leaf spring assembly parameters, the unsprung mass, and the wheelbase data, and integrate them into the suspension steering motion simulation basic data set. Build a multi-body dynamics simulation model, add the leaf spring elastic constraint, the tire grounding constraint, and the steering system motion pair, and correlate the hard point parameters and the whole vehicle structure components. Set the flat jump simulation working condition and the braking simulation working condition, and define the simulation output parameter type. Run the simulation model, collect the space clearance data of the steering components and the frame and the front axle, and the lateral displacement data during braking, calculate the flat jump interference evaluation parameter a and the braking deviation evaluation parameter b. If a > 0.2 or b > 0.5, locally adjust the Z coordinate or Y coordinate of the hard point, repeat the simulation until the parameters meet the threshold requirements, and finally obtain the hard point parameters.

7. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 1, wherein, S107 specifically includes the following steps: Define the target parameters of the steering transmission system, determine the target transmission ratio cm, the target number of turns nm of the steering wheel, and the target turning radius Rm. Import the adjusted steering system hard point parameters, correlate the transmission components such as the steering gear, the rocker arm, and the steering straight tie rod, and build a steering transmission system simulation model. Define the optimization variables steering gear transmission ratio i and rocker arm effective length La, set the constraint conditions including the parameter value range and the adaptation requirements to the Ackerman angle, and run the simulation model for iterative optimization. Collect the actual transmission ratio c, the number of turns nl / nr of the steering wheel, and the actual turning radius R, and calculate Δc, Δn, and ΔR. Check if the evaluation parameters meet the threshold requirements, if not, fine-tune the optimization variables and repeat the simulation, if yes, lock the final transmission parameters.

8. The method of optimizing a four-wheel drive recreational vehicle steering drive mechanism according to claim 1, wherein, S108 specifically includes the following steps: Integrate the steering trapezoidal parameters, steering system hard point parameters and transmission performance parameters, establish a unified parameter dataset, and label the source and constraints of each parameter; Check if the parameters meet the design targets, including the steering trapezoidal angle difference, the flat jump interference a, the braking deviation b, and the transmission evaluation parameters Δc, Δn, and ΔR; Build a whole vehicle level steering transmission coupling simulation model, correlate the steering system with the suspension and brake system, and simulate the cooperative working state under complex working conditions; Verify the boundary conditions, including maximum angle steering, extreme braking, full load / empty load switching conditions, and collect overall performance data; Configure all the parameters that meet the standards, organize the parameter documents according to the whole vehicle design specifications, clarify the installation reference and tolerance requirements of the parameters, and output the final optimization results.

9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to realize the optimization design method steps of the four-wheel drive recreational vehicle steering transmission mechanism according to any one of claims 1-8.

10. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to realize the optimization design method steps of the four-wheel drive recreational vehicle steering transmission mechanism according to any one of claims 1-8.

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