Model construction and parameter determination method for recreational vehicle inertial air suspension

Abstract

The invention discloses a limo inertial air suspension model construction and parameter determination method in the technical field of vehicle suspension vibration isolation. The limo inertial air suspension model construction and parameter determination method comprises the following steps: S1, analyzing force output characteristics of an air spring and establishing a mechanical output model; s2, according to the structure of the recreational vehicle inertial air suspension and the mechanical output model of the air spring, establishing a dynamic model of the recreational vehicle inertial air suspension; s3, according to the kinetic model of the recreational vehicle inertial air suspension, parameters of the recreational vehicle inertial air suspension are optimized and determined based on a particle swarm algorithm; and S4, performing simulation verification on the kinetic model of the recreational vehicle inertial air suspension according to the parameters of the recreational vehicle inertial air suspension. According to the recreational vehicle inerter air suspension model construction and parameter determination method, the parameter design and optimization time can be greatly shortened, the design efficiency is effectively improved, the'inerter-spring-damping 'suspension technology is promoted, and the development of the automobile engineering field is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle suspension vibration isolation, and in particular to a method for constructing an inertial air suspension model of a motorhome and determining parameters. Background Art

[0002] The high-performance RV inertia air suspension combines the air suspension that can flexibly adjust the vehicle body height to adapt to different road conditions and driving requirements, and the dynamic response characteristics of the inertia container, providing high-performance RVs with more outstanding handling performance and ride comfort.

[0003] The concept of inertia chamber was proposed by Professor Smith of Cambridge University in the UK. It is a two-terminal characteristic element whose output force is proportional to the relative acceleration of the two ends. The introduction of inertia chamber breaks the inherent structure of "spring-damper" of traditional suspension and forms a vehicle suspension based on the "inertia chamber-spring-damper" structure. Compared with elastic elements, inertia chamber has frequency-dependent negative stiffness characteristics, and the frequency response curve of the vibration isolation system equipped with inertia chamber shows obvious anti-resonance peak. By utilizing this characteristic and combining the advantages of inertia chamber and air suspension, the vibration isolation performance of the vehicle can be effectively improved.

[0004] However, during the entire design and manufacturing process of the inertial air suspension, different design teams are responsible for the design of different parameter values. After all parameter values ​​are designed, they are manufactured according to these parameter values. Due to the large number of parameters, each parameter will affect each other. Usually, the inertial air suspension manufactured according to the parameter values ​​designed in the early stage cannot meet the requirements in the vehicle debugging test. This requires each design team to continue to communicate with each other based on the test results, constantly redesign the values ​​of each parameter, and debug repeatedly until the manufactured inertial air suspension meets the requirements. This way of designing and manufacturing inertial air suspension is time-consuming and labor-intensive, and greatly affects work efficiency. Summary of the invention

[0005] The present application provides a method for constructing an inertial air suspension model and determining parameters of a motorhome, analyzes the dynamic performance of an inertial air suspension system equipped with an inertia container, studies the parameter matching problem between the air suspension and the inertia container, greatly reduces the parameter design and optimization time, and effectively improves work efficiency.

[0006] The present application embodiment provides a method for constructing an inertia air suspension model of a motorhome and determining parameters, comprising the following steps:

[0007] S1: Analyze the force output characteristics of the air spring and establish a mechanical output model;

[0008] S2: establishing a dynamics model of the inertia air suspension of the RV according to the structure of the inertia air suspension of the RV and the mechanical output model of the air spring;

[0009] S3: According to the dynamics model of the RV inertia air suspension, the parameters of the RV inertia air suspension are optimized based on a particle swarm algorithm;

[0010] S4: performing simulation verification on a dynamics model of the RV inertia air suspension according to the parameters of the RV inertia air suspension.

[0011] In one embodiment of the present application, in step S1, the mechanical output model of the air spring is:

[0012]

[0013] Among them, P e A is the effective air pressure of the air spring; e is the effective force area of ​​the air spring; p0 is the initial effective air pressure of the air spring; p a is the standard atmospheric pressure; v0 is the initial volume of the air spring; n is the thermodynamic coefficient; x is the working height of the air spring.

[0014] In one embodiment of the present application, the inertial air suspension includes an air spring, a damper and an inertial container that are interconnected.

[0015] In one embodiment of the present application, the dynamic model of the RV inertial air suspension includes:

[0016] The dynamic model of the parallel RV inertial air suspension in which the air spring, damper and inertia container are connected in parallel is as follows:

[0017]

[0018] The dynamic model of the series RV inertia air suspension in which the damper is connected in series with the inertia container and the air spring is connected in parallel with the damper and the inertia container is as follows:

[0019]

[0020] Among them, m s is the sprung mass; m u is the unsprung mass; k r is the tire stiffness; z s is the sprung mass displacement; z u is the unsprung mass displacement; b is the inertia coefficient; c is the damping coefficient; z r It is a road surface excitation model.

[0021] In one embodiment of the present application, the road surface excitation model z generated based on the filtered white noise method r ,as follows:

[0022]

[0023] Among them G q (n0) is the road roughness coefficient; v is the vehicle speed; ω(t) is the Gaussian white noise with zero mean.

[0024] In one embodiment of the present application, step S3 is specifically as follows:

[0025] S3.1: Determine the parameters to be optimized as the inertia coefficient b and the damping coefficient c, and initialize the particles;

[0026] S3.2: The root mean square value of the vehicle acceleration J1, the root mean square value of the suspension travel J2, and the root mean square value of the tire dynamic load J3 under random road input conditions are set as optimization targets, and the multi-objective function is dimensionlessly transformed into a single-objective function f, as follows:

[0027] f=0.6×J1 / J 1pas +0.2×J2 / J 2pas +0.2×J3 / J 3pas ;

[0028] Among them, J 1pas , J 2pas , J 3pas They are the RMS value of body acceleration, RMS value of suspension dynamic travel and RMS value of tire dynamic load of the traditional air suspension without inertia container;

[0029] S3.3: Set the performance constraints of the RV inertial air suspension and the constraints of the suspension parameters:

[0030] The three performance indicators of the RV inertial air suspension are compared with the performance indicators of the traditional air suspension. If any of the indicators is smaller than the value corresponding to the traditional air suspension, a penalty value is set to 100, otherwise it is set to 0. The performance constraint condition of the suspension can be written as: (J1≥J 1pas ) or (J2≥J 2pas ) or (J3≥J 3pas );

[0031] The constraints for setting the inertial air suspension parameters of the RV are:

[0032] S3.4: Calculate the individual extreme value and the global extreme value: the individual extreme value is the value of the objective function f obtained by the particle at the optimal position, and the global extreme value is the optimal value among the individual extreme values ​​of all particles. The speed and position of each particle are:

[0033]

[0034] Among them, vj (t) is the velocity of particle j in the tth generation; w is the weight; r1 and r2 are random numbers in the range of [0-1]; p j (t) is the individual optimal particle position; p g (t) is the global optimal particle position;

[0035] Individual optimal particle position p j (t) is the optimal position of particle j in the previous t generations, and its update equation is:

[0036]

[0037] Global optimal particle position p g (t) is:

[0038] p g (t) = argmin{f(p j (t))∣j=1, 2,...,n};

[0039] S3.5: Set the upper limit of particle speed:

[0040] |v jk (t+1)|≤v max ;

[0041] Boundary processing: When a particle moves to the boundary of the space, it is forced to stop moving, the current speed is set to 0, and the fitness of the particle is calculated according to the current boundary position;

[0042] S3.6: Use Matlab / Simulink to find the optimal solution of the objective function and its corresponding parameters.

[0043] In one embodiment of the present application, in step S4, the simulation verification uses a traditional air suspension system dynamics model as a comparison reference, and the traditional air suspension system dynamics model is as follows:

[0044]

[0045] Among them, m s is the sprung mass; m u is the unsprung mass; k r is the tire stiffness; z s is the sprung mass displacement; z u is the unsprung mass displacement; b is the inertia coefficient; c is the damping coefficient; c0 is the damping coefficient of the traditional air suspension.

[0046] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0047] 1. The RV inertia air suspension model construction and parameter determination method proposes a RV inertia air suspension dynamics model, which lays the foundation for the subsequent RV inertia air suspension structure parameter determination and performance analysis;

[0048] 2. In the model construction and parameter determination method of the RV inertia air suspension, a method for determining the inertia coefficient and damping parameters of the inertia container is proposed, which can obtain the optimal structure of the series RV inertia air suspension and the parallel RV inertia air suspension under a certain state, and then optimize the design and performance analysis of the suspension system, deeply understand its dynamic characteristics and response characteristics, and help improve the control accuracy and stability of the vehicle;

[0049] 3. The model construction and parameter determination method of the RV inertial air suspension can greatly reduce the parameter design and optimization time, effectively improve the design efficiency, and is conducive to the promotion of the "inertia container-spring-damper" suspension technology and the development of the automotive engineering field. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0051] Figure 1 It is a flow chart of the steps of the method for constructing an inertial air suspension model and determining parameters of a motorhome;

[0052] Figure 2 It is a schematic diagram of the dynamic model of the inertial air suspension of a parallel RV;

[0053] Figure 3 It is a schematic diagram of the dynamic model of the inertial air suspension of a series RV. DETAILED DESCRIPTION

[0054] The present invention is further explained below in conjunction with specific implementation methods. It should be understood that these implementation methods are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0055] Example:

[0056] like Figure 1 As shown, a method for constructing an inertial air suspension model of a motorhome and determining parameters includes the following steps:

[0057] S1: Analyze the force output characteristics of the air spring and establish a mechanical output model.

[0058] Specifically:

[0059] According to the relationship between output force and pressure, the output force of the air spring is:

[0060] F A =P e ×A e (1);

[0061] The ideal gas state equation is:

[0062] (p0+p a )v0 n =(P e +p a )v n (2);

[0063] When the air spring is working, the change in volume is related to the working height and the effective force area, which can be written as:

[0064] v=v0-A e x (3);

[0065] Then the mechanical output model of the air spring is:

[0066]

[0067] Among them, P e A is the effective air pressure of the air spring; e is the effective force area of ​​the air spring; p0 is the initial effective air pressure of the air spring; p a is the standard atmospheric pressure; v0 is the initial volume of the air spring; n is the thermodynamic coefficient; x is the working height of the air spring.

[0068] The air spring parameters of this example are shown in Table 1:

[0069]

[0070] The mechanical output model of the air spring is constructed using the above parameters.

[0071] S2: According to the structure of the RV inertia air suspension and the mechanical output model of the air spring, a dynamic model of the RV inertia air suspension is established.

[0072] like Figure 2 As shown, the structural characteristics of the parallel RV inertia air suspension system are as follows: the sprung mass and the unsprung mass are connected by three components: an air spring, a damper, and an inertia container, and the connection relationship is that the air spring, the damper, and the inertia container are connected in parallel.

[0073] According to the above connection relationship, the dynamic quarter model of the parallel RV inertia air suspension system is constructed as follows:

[0074]

[0075] like Figure 3 As shown, the structural characteristics of the series RV inertia air suspension system are as follows: the sprung mass and the unsprung mass are connected by three components: the air spring, the damper, and the inertia container. The connection relationship is that the damper and the inertia container are connected in series, and the air spring, the damper, and the inertia container are connected in parallel.

[0076] According to the above connection relationship, the dynamics quarter model of the inertial air suspension system of the series RV is constructed as follows:

[0077]

[0078] Among them, m s is the sprung mass; m u is the unsprung mass; k r is the tire stiffness; z s is the sprung mass displacement; z u is the unsprung mass displacement; b is the inertia coefficient; c is the damping coefficient.

[0079] Constructing a traditional air suspension system dynamics model:

[0080]

[0081] Among them, m s is the sprung mass; m u is the unsprung mass; k r is the tire stiffness; z s is the sprung mass displacement; z u is the unsprung mass displacement; b is the inertia coefficient; c is the damping coefficient; c0 is the damping coefficient of the traditional air suspension.

[0082] Construct a road excitation model based on the filtered white noise method r as follows:

[0083]

[0084] Among them, G q (n0) is the road roughness coefficient; v is the vehicle speed; ω(t) is the Gaussian white noise with zero mean.

[0085] S3: According to the dynamics model of the RV inertia air suspension, the RV inertia air suspension parameters are determined based on the particle swarm algorithm optimization.

[0086] Specifically:

[0087] S3.1: Determine the parameters to be optimized as the inertia coefficient b and the damping coefficient c, and initialize the particles;

[0088] The design parameters set in this embodiment are shown in Table 2:

[0089]

[0090] S3.2: The root mean square value of the vehicle acceleration J1, the root mean square value of the suspension travel J2, and the root mean square value of the tire dynamic load J3 under random road input conditions are set as optimization targets, and the multi-objective function is dimensionlessly transformed into a single-objective function:

[0091] f=0.6×J1 / J 1pas +0.2×J2 / J 2pas +0.2×J3 / J 3pas (9);

[0092] Among them, J 1pas , J 2pas , J 3pas They are the RMS value of body acceleration, RMS value of suspension dynamic travel and RMS value of tire dynamic load of traditional air suspension without inertia container.

[0093] S3.3: Set the performance constraints of the RV inertial air suspension and the constraints of the suspension parameters:

[0094] The three performance indicators of the RV inertial air suspension are compared and constrained with the performance indicators of the traditional air suspension. If one of the indicators is smaller than the value corresponding to the indicator of the conventional air suspension, a penalty value is set to 100, otherwise it is set to 0. In summary, the performance constraint of the suspension can be written as:

[0095] (J1≥J 1pas ) or (J2≥J 2pas ) or (J3≥J 3pas ) (10);

[0096] The constraints for setting the inertial air suspension parameters of the RV are:

[0097]

[0098] S3.4: Calculate the individual extreme value and the global extreme value: the individual extreme value is the value of the objective function f obtained by the particle at the optimal position, and the global extreme value is the optimal value among the individual extreme values ​​of all particles. The speed and position of each particle are:

[0099]

[0100] Among them, v j (t) is the velocity of particle j in the tth generation; w is the weight; r1 and r2 are random numbers in the range of [0-1]; p j(t) is the individual optimal particle position; p g (t) is the global optimal particle position;

[0101] Individual optimal particle position p j (t) is the optimal position of particle j in the previous t generations, and its update equation is:

[0102]

[0103] Global optimal particle position p g (t) is:

[0104] p g (t) = argmin{f(p j (t))|j=1, 2,...,n} (14);

[0105] S3.5: Set the upper limit of particle speed:

[0106] |v jk (t+1)|≤v max (15);

[0107] Boundary processing: When a particle moves to the boundary of space, it is forced to stop moving, the current speed is set to 0, and the fitness of the particle is calculated according to the current boundary position.

[0108] S3.6: Use Matlab / Simulink to find the optimal solution of the objective function and its corresponding parameters.

[0109] The vehicle speed is set to 20 m / s, driving on a Class B road, the simulation duration is set to 10 s, and the sampling time is 0.001 s.

[0110] Table 3 shows the results of the inertia air suspension parameter optimization of the parallel RV in this embodiment:

[0111]

[0112] Table 4 shows the results of the inertial air suspension parameter optimization of the series high-performance RV in this embodiment:

[0113]

[0114] S4: According to the parameters of the RV inertia air suspension, the dynamic model of the RV inertia air suspension is simulated and verified, and the dynamic performance is analyzed.

[0115] Specifically:

[0116] Matlab / Simulink is used to build a parallel RV inertia air suspension model, a series RV inertia air suspension model and a traditional air suspension model. The simulation conditions are set with a vehicle speed of 20 m / s, driving on a Class B road, a simulation time of 10 s, and a sampling time of 0.001 s.

[0117] Table 5 is a comparison of the RMS values ​​of the three suspensions:

[0118]

[0119] According to the results in Table 5, the parallel RV inertial air suspension system using the method proposed in the present invention has a body acceleration root mean square value reduced by 2.3%, a suspension dynamic stroke root mean square value reduced by 19.4%, and a tire dynamic load root mean square value reduced by 5.6% under the above simulation conditions compared with the traditional air suspension system. The series RV inertial air suspension system using the method proposed in the present invention has a body acceleration root mean square value reduced by 6.2%, a suspension dynamic stroke root mean square value reduced by 16.7%, and a tire dynamic load root mean square value reduced by 11.1% under the above simulation conditions compared with the traditional air suspension system.

[0120] It can be seen that the RV inertial air suspension model construction and parameter determination method can effectively obtain better parameters, greatly reduce parameter design and optimization time, and improve work efficiency; and the better parallel high-performance RV inertial air suspension and series high-performance RV inertial air suspension can improve the vehicle's vibration isolation performance and improve the smoothness of the car's driving.

[0121] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for constructing an inertial air suspension model of a motorhome and determining parameters, characterized in that: The following steps are involved: S1: Analyze the force output characteristics of the air spring and establish a mechanical output model; S2: establishing a dynamics model of the inertia air suspension of the RV according to the structure of the inertia air suspension of the RV and the mechanical output model of the air spring; S3: According to the dynamics model of the RV inertia air suspension, the parameters of the RV inertia air suspension are optimized based on a particle swarm algorithm; S4: performing simulation verification on a dynamics model of the RV inertia air suspension according to the parameters of the RV inertia air suspension.

2. The method for constructing a motorhome inertial air suspension model and determining parameters according to claim 1 is characterized in that: In step S1, the mechanical output model of the air spring is: Among them, P e is the effective air pressure of the air spring; A e is the effective force area of ​​the air spring; p0 is the initial effective air pressure of the air spring; p a is the standard atmospheric pressure; v0 is the initial volume of the air spring; n is the thermodynamic coefficient; x is the working height of the air spring.

3. The method for constructing a motorhome inertial air suspension model and determining parameters according to claim 1, characterized in that: The motorhome inertia air suspension includes the air spring, the damper and the inertia container which are connected to each other.

4. The method for constructing a motorhome inertial air suspension model and determining parameters according to claim 3 is characterized in that: The dynamic model of the RV inertial air suspension includes: The dynamic model of the parallel RV inertial air suspension in which the air spring, damper and inertia container are connected in parallel is as follows: The dynamic model of the series RV inertia air suspension in which the damper is connected in series with the inertia container and the air spring is connected in parallel with the damper and the inertia container is as follows: Among them, m s is the sprung mass; m u is the unsprung mass; k r is the tire stiffness; z s is the sprung mass displacement; z u is the unsprung mass displacement; b is the inertia coefficient; c is the damping coefficient; z r It is a road surface excitation model.

5. The method for constructing a motorhome inertial air suspension model and determining parameters according to claim 4 is characterized in that: Road surface excitation model generated based on filtered white noise method r ,as follows: Among them G q (n0) is the road roughness coefficient; v is the vehicle speed; ω(t) is the Gaussian white noise with zero mean.

6. The method for constructing a motorhome inertial air suspension model and determining parameters according to claim 3 is characterized in that: The step S3 is specifically as follows: S3.1: Determine the parameters to be optimized as the inertia coefficient b and the damping coefficient c, and initialize the particles; S3.2: The root mean square value of the vehicle acceleration J1, the root mean square value of the suspension travel J2, and the root mean square value of the tire dynamic load J3 under random road input conditions are set as optimization targets, and the multi-objective function is dimensionlessly transformed into a single-objective function f, as follows: f=0.6×J1 / J 1pas +0.2×J2 / J 2pas +0.2×J3 / J 3pas ; Among them, J 1pas , J 2pas , J 3pas They are the RMS value of body acceleration, RMS value of suspension dynamic travel and RMS value of tire dynamic load of the traditional air suspension without inertia container; S3.3: Setting the performance constraints and parameter constraints of the RV inertial air suspension: The three performance indicators of the RV inertial air suspension are compared and constrained with the performance indicators of the traditional air suspension. If any of the indicators is smaller than the value corresponding to the indicator of the traditional air suspension, the penalty value is set to 100, otherwise it is set to 0. The performance constraint condition of the suspension can be written as: (J1≥J 1pas ) or (J2≥J 2pas ) or (J3≥J 3pas ); The constraints for setting the parameters of the RV inertial air suspension are: S3.4: Calculate the individual extreme value and the global extreme value: the individual extreme value is the value of the objective function f obtained by the particle at the optimal position, and the global extreme value is the optimal value among the individual extreme values ​​of all particles. The speed and position of each particle are: Among them, v j (t) is the velocity of particle j in the tth generation; w is the weight; r1 and r2 are random numbers in the range of [0-1]; p j (t) is the individual optimal particle position; p g (t) is the global optimal particle position; Among them, the individual optimal particle position p j (t) is the optimal position of particle j in the previous t generations, and its update equation is: Global optimal particle position p g (t) is: p g (t) = argmin{f(p j (t))∣j=1, 2,...,n}; S3.5: Set the upper limit of particle speed: |v jk (t+1)|≤v max ; S3.6: Find the optimal solution of the objective function and the corresponding parameters.

7. The method for constructing a motorhome inertial air suspension model and determining parameters according to claim 4 is characterized in that: In step S4, the simulation verification uses a traditional air suspension system dynamics model as a comparison reference, and the traditional air suspension system dynamics model is as follows: Among them, m s is the sprung mass; m u is the unsprung mass; k r is the tire stiffness; z s is the sprung mass displacement; z u is the unsprung mass displacement; b is the inertia coefficient; c is the damping coefficient; c0 is the damping coefficient of the traditional air suspension.

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