A power flow based control method for a dynamic inertia suspension

Abstract

The application discloses a power flow based dynamic inertia suspension control method, comprising the following steps: step 1, establishing a dynamic inertia suspension structure and building a dynamic inertia suspension model; step 2, calculating the vibration power flowing into the dynamic inertia suspension; step 3, selecting a sprung mass as a vibration isolation object; step 4, determining the power flow based dynamic inertia suspension control method; step 5, determining dynamic inertia suspension performance indexes and comprehensive indexes; step 6, optimizing and determining dynamic inertia suspension parameters according to the dynamic inertia suspension performance indexes; and step 7, semi-actively realizing the power flow based dynamic inertia suspension control method. The control method greatly improves the dynamic inertia suspension performance; compared with an active suspension with high energy consumption, the semi-active realization has much lower energy consumption, reduces energy consumption, and meets the theme of energy saving, emission reduction and green environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle suspension control, and particularly relates to a power flow based dynamic inertia suspension control method. BACKGROUND

[0002] The suspension system is a general term for the force transmission and connecting device between the vehicle frame and the axle or wheel, as a main component of the vehicle, together with the tire and seat, it forms the three major systems of vehicle damping, and as the most important damping system among the three, it plays a crucial role in the ride comfort, handling stability and ride comfort of the vehicle.

[0003] The vehicle suspension has a history of nearly a hundred years, the traditional passive suspension as the first developed typical suspension structure, its technology is more mature than semi-active and active suspension, and the traditional passive suspension with "spring-damping" as the core element has been used until now because it does not need a controller, the structure is simpler, and the cost is lower; however, after nearly a hundred years of development, the performance improvement of the traditional passive suspension has gradually approached the limit, in order to obtain better suspension performance, domestic and foreign experts and scholars have made a lot of research, but the effect is very small; at the same time, the fixed parameters make the traditional passive suspension have low inclusiveness for road conditions, it is difficult to ensure that the vehicle ride comfort and handling stability are always in the optimal state, and also makes it difficult for automobile manufacturers to meet market demand; the concept of "inertial damper" is proposed and applied subsequently, which breaks the traditional passive suspension structure of "spring-damping"; the suspension using the inertial damper is called "dynamic inertia suspension"; at the same time, the application of semi-active control in suspension is also developing rapidly, the appearance of the inertial damper and the two-way development of the control method provide a broad space for further improvement of the suspension performance.

[0004] Under the theme of green environmental protection, active control suspension often needs to consume a large amount of energy to realize the control of the suspension, semi-active control becomes the main choice for the improvement of the suspension performance because of its low energy consumption, however, the current semi-active control method is mostly proposed for damping control, such as the widely recognized skyhook damping control, groundhook damping control and acceleration driven damping control; the improvement of the inertial damper on the suspension performance has been confirmed by many research institutes, but there are few semi-active control methods suitable for dynamic inertia suspension, which limits the development of dynamic inertia suspension, and the suspension performance cannot be further improved.

[0005] In view of the above situation, it is necessary to improve the existing dynamic inertia suspension control method, so that it can adapt to the needs of the control of the dynamic inertia suspension. SUMMARY

[0006] The purpose of the present application is to solve the defects of the existing dynamic inertia suspension control method, which restricts its development and has a certain impact on the suspension performance. Therefore, a control method for the inertial container in the dynamic inertia suspension is proposed and semi-active implementation is carried out, which solves the problem that the semi-active control method based on the damper cannot be well matched with the dynamic inertia suspension, further improves the performance of the dynamic inertia suspension, and provides ideas for the subsequent development of the dynamic inertia suspension control method.

[0007] The technical scheme of the present application for achieving the above-mentioned purpose is a dynamic inertia suspension control method based on power flow, comprising the following steps:

[0008] Step 1: Establishing a dynamic inertia suspension structure and building a dynamic inertia suspension model;

[0009] Step 2: Calculating the vibration power flowing into the dynamic inertia suspension;

[0010] Step 3: Selecting the sprung mass as the vibration isolation object;

[0011] Step 4: Determining the dynamic inertia suspension control method based on power flow;

[0012] Step 5: Determining the dynamic inertia suspension performance index and comprehensive index;

[0013] Step 6: Optimizing the dynamic inertia suspension parameters according to the dynamic inertia suspension performance index;

[0014] Step 7: Semi-active implementation of the dynamic inertia suspension control method based on power flow.

[0015] Further supplement to the technical scheme, the dynamic inertia suspension structure in step 1 is a dynamic inertia suspension structure in which the damper and the inertial container are connected in series and then connected in parallel with the spring.

[0016] Further supplement to the technical scheme, the dynamic inertia suspension model in step 1 is a dynamic inertia suspension structure in which one end of the dynamic inertia suspension structure is connected to the sprung mass, the other end of the dynamic inertia suspension structure is connected to the non-sprung mass, and the non-sprung mass is connected to the road surface through the equivalent spring of the non-sprung mass.

[0017] Further supplement to the technical scheme, the vibration power P flowing into the dynamic inertia suspension in step 2 is: sus

[0018]

[0019] where z1 is the vertical displacement of the non-sprung mass, is the vertical velocity of the non-sprung mass, z2 is the vertical displacement of the sprung mass, is the vertical velocity of the sprung mass, is the vertical acceleration of the sprung mass,​ is the vertical velocity of the inertia damper and the suspension spring connection point, is the vertical acceleration of the inertia damper and the suspension spring connection point, k is the suspension spring, c is the damper, and b is the inertia damper;

[0020] wherein, according to the dynamic structure relationship of the damper and the inertia damper in series in the dynamic inertia suspension, the vibration power P sus may be further rewritten as:

[0021] Further supplement to the technical solution, the dynamic inertia suspension control method in step 4 is to adjust the dynamic inertia suspension element parameters so that the vertical acceleration of the sprung mass tends to 0, that is, tends to 0.

[0022] Further supplement to the technical solution, the dynamic inertia suspension performance index in step 5 is:

[0023] the sprung mass-suspension vibration power transmission ratio P spru / sus :

[0024]

[0025] the spring-sprung mass vibration power transmission ratio P spri / spru :

[0026]

[0027] the sprung mass acceleration root mean square value BA:

[0028]

[0029] the non-sprung mass dynamic load root mean square value DTL:

[0030]

[0031] the suspension dynamic travel root mean square value SWS:

[0032]

[0033] where i represents the i-th sample, N represents the total number of samples, z r represents the road input vertical displacement, k t represents the equivalent spring stiffness of the non-sprung mass.

[0034] Further supplement to the technical solution, the comprehensive index in step 5 is:

[0035] T=a·P spru / sus +b·P spri / spru+c·BA+d·DTL+f·SWS

[0036] Wherein a, d, c, d, e, f are the optimization coefficients of each dynamic inertia suspension performance index.

[0037] Further supplement to the technical solution, the optimization coefficients are a=0.25, b=0.15, c=0.3, d=0.1, and f=0.2.

[0038] Further supplement to the technical solution, the optimization method in step 6 is any one or a combination of more than one of a fish swarm algorithm, an ant colony algorithm, a particle swarm algorithm, a genetic algorithm, and a simulated annealing algorithm.

[0039] Further supplement to the technical solution, the power flow-based dynamic inertia suspension control method semi-active implementation in step 7 includes the following two implementation forms:

[0040] One is a power-driven inertance control method semi-active implementation:

[0041]

[0042] Wherein b min represents that the inertance takes a minimum value, b max represents that the inertance takes a maximum value, b mid represents that the inertance takes an intermediate value.

[0043] The other is a power-driven inertance-damping control method semi-active implementation:

[0044]

[0045] Wherein c min represents that the damper takes a minimum value, c max represents that the damper takes a maximum value, c mid represents that the damper takes an intermediate value.

[0046] The beneficial effects are as follows: 1. The control method no longer relies on the damper to achieve semi-active control of the suspension, and is not only suitable for adjusting the parameters of the inertance alone, but also suitable for adjusting the parameters of the damper and the inertance at the same time, so that the control method can be fully matched with the dynamic inertia suspension; the damper control method based on the traditional "spring-damper" suspension structure does not need to be applied to the dynamic inertia suspension, reducing the occurrence of invalidation of the damper control method used in the dynamic inertia suspension; thereby further improving the performance of the dynamic inertia suspension and the ride comfort and road friendliness of the vehicle;

[0047] 2. The dynamic inertia suspension control method is semi-actively implemented, and the performance of the dynamic inertia suspension is greatly improved compared with the passive suspension whose parameters cannot be adjusted; compared with the active suspension which consumes more energy, the semi-active implementation consumes much less energy, reduces energy consumption, and meets the theme of energy saving, emission reduction and environmental protection;

[0048] 3. The suspension structure of the dynamic inertia suspension still has better suspension performance than the traditional "spring-damping" parallel structure in the uncontrolled state, which ensures the ride comfort of the vehicle when the dynamic inertia suspension control method fails.

[0049] 4. The control method is a control method based on vibration energy, which is more stable than the control method with acceleration as the control target. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The dynamic inertia suspension structure model of the present application;

[0051] Figure 2 The quarter ideal dynamic inertia suspension model of the present application;

[0052] Figure 3 The two implementation forms of the dynamic inertia suspension control method based on power flow of the present application and the comparison of common suspension performance;

[0053] In the figure: k1 is the main spring, k2 is the auxiliary spring, m1 is the unsprung mass, m2 is the sprung mass, k t is the equivalent spring of the unsprung mass, k is the suspension spring, c is the damper, b is the inertial container, z r is the vertical displacement of the road input, z1 is the vertical displacement of the unsprung mass, z2 is the vertical displacement of the sprung mass, and z3 is the vertical displacement of the connection point of the inertial container and the damper. DETAILED DESCRIPTION

[0054] In order to make the technical personnel in the art more clearly understand the present technical solution, the specific structure and principle of each mechanism will be explained below with reference to the accompanying drawings. Figures 1-3 The dynamic inertia suspension control method based on power flow includes the following steps:

[0055] Step 1: Establish the dynamic inertia suspension structure and build the dynamic inertia suspension model;

[0056] The dynamic inertia suspension structure is mainly eight structures obtained by arranging and combining spring, damper and inertial container in series or parallel. The dynamic inertia suspension structure is a dynamic inertia suspension structure in which the damper and the inertial container are connected in series and then connected in parallel with the spring. However, when the dynamic inertia suspension structure is in use, the suspension elements cannot be reset and the elements cannot be broken, so no matter which dynamic inertia suspension structure is used, a spring needs to be connected at one end with the sprung mass and at the other end with the unsprung mass, thereby ensuring the safety of the dynamic inertia suspension structure.

[0057] The dynamic inertia suspension structure includes the following eight structures:

[0058] Structure 1: The main spring k1, the inertial container b and the damper c are connected in series and then connected in parallel with the auxiliary spring k2.

[0059] Structure 2: The inertial container b and the damper c are connected in series and then connected in parallel with the main spring k1.

[0060] Structure 3: The main spring k1 and the inertial container b are connected in parallel and then connected in series with the damper c. In order to ensure the safety of the dynamic inertia suspension structure, the auxiliary spring k2 is finally connected in parallel.

[0061] Structure 4: The main spring k1, the inertial container b and the damper c are connected in parallel.

[0062] Structure 5: The main spring k1 and the damper c are connected in series and then connected in parallel with the inertial container b. In order to ensure the safety of the dynamic inertia suspension structure, the auxiliary spring k2 is finally connected in parallel.

[0063] Structure 6: The main spring k1 and the inertial container b are connected in series and then connected in parallel with the damper c. In order to ensure the safety of the dynamic inertia suspension structure, the auxiliary spring k2 is finally connected in parallel.

[0064] Structure 7: The main spring k1 and the damper c are connected in parallel and then connected in series with the inertial container b. In order to ensure the safety of the dynamic inertia suspension structure, the auxiliary spring k2 is finally connected in parallel.

[0065] Structure 8: The main spring k1 and the damper c are connected in parallel and then connected in series with the inertial container b. In order to ensure the safety of the dynamic inertia suspension structure, the auxiliary spring k2 is finally connected in parallel.

[0066] The performance of the dynamic inertia suspension in different structures is compared and analyzed, and structure 2 is selected as the dynamic inertia suspension structure and a dynamic inertia suspension model as shown in FIG. 2 is built. Figure 2 When in operation, one end of the structure 2 is connected with the sprung mass m2, and the other end of the structure 2 is connected with the unsprung mass m1. The unsprung mass m1 is connected with the road input vertical displacement z t through the equivalent spring k r of the unsprung mass.

[0067] Step 2: Calculate the vibration power flowing into the inertance suspension;

[0068] The vibration power flowing into the inertance suspension in step 2 P sus is:

[0069]

[0070] where z1 is the vertical displacement of the unsprung mass, is the vertical velocity of the unsprung mass, z2 is the vertical displacement of the sprung mass, is the vertical velocity of the sprung mass, is the vertical acceleration of the sprung mass, is the vertical velocity of the inertance damper connection point, is the vertical acceleration of the inertance damper connection point, k is the suspension spring, c is the damper, and b is the inertance damper.

[0071] According to the dynamic structure relationship of the inertance suspension in which the damper and the inertance damper are connected in series, the vibration power P sus can be further rewritten as:

[0072] Step 3: Select the sprung mass as the vibration isolation object to ensure the ride comfort of the vehicle during driving;

[0073] The reason for selecting the vibration power and the sprung mass m2 is that during the driving of the vehicle, a certain amount of vibration power is transmitted to the vehicle through the tires, the more vibration power absorbed and consumed by the suspension, the less vibration power affecting the vehicle body (i.e., the sprung mass m2), reducing the dizziness caused by vehicle vibration, thereby providing a more comfortable ride experience for passengers.

[0074] When the sprung mass m2 is selected as the vibration isolation object, to ensure the ride comfort of the vehicle, the vertical acceleration of the sprung mass m2 should be as close to 0 as possible. However, only pursuing the vertical acceleration of the sprung mass m2 tending to 0 will lead to instability of the inertance suspension, therefore, from the perspective of energy, the inertance suspension control method is designed with the goal of the vibration power in the sprung mass m2 tending to 0. When the vibration power in the sprung mass m2 tends to 0, the vibration power flowing into the inertance suspension P sus can be further simplified to:

[0075] When the vibration power in the sprung mass m2 tends to 0, the vibration power flowing into the inertance suspension P susAlso tends to 0, so when P sus > 0, more vibration energy is stored in the inertance suspension, the sprung mass m2 slows down the tendency to move away from or close to the unsprung mass m1, at this time the damper c and the inertance b in the inertance suspension should be switched to the minimum value to keep the movement tendency of the sprung mass m2. When P sus < 0, more vibration energy is transmitted to the sprung mass m2 or the unsprung mass m1, the sprung mass m2 intensifies the tendency to move away from or close to the unsprung mass m1, at this time the damper c and the inertance b in the inertance suspension should be switched to the maximum value to prevent such movement tendency of the sprung mass m2.

[0076] Step 4: Determine the inertance suspension control method based on power flow;

[0077] Among them, the inertance suspension control method is to adjust the inertance suspension element parameters so that is the vertical acceleration of the sprung mass tends to 0, that is tends to 0.

[0078] Step 5: Determine the inertance suspension performance index and comprehensive index;

[0079] From the analysis of step 4, the amount of vibration energy in the inertance suspension is an important indicator that affects the movement tendency of the sprung mass m2, so the sprung mass-suspension vibration power transmission ratio P spru / sus and the spring-sprung mass vibration power transmission ratio P spri / spru are selected as the performance indicators of the inertance suspension,

[0080] Among them, the sprung mass-suspension vibration power transmission ratio P spru / sus :

[0081]

[0082] The spring-sprung mass vibration power transmission ratio P spri / spru :

[0083]

[0084] And the sprung mass acceleration gain BA, the unsprung mass dynamic load gain DTL, and the suspension dynamic travel root mean square value SWS represent the ride comfort, road friendliness, and suspension safety of the vehicle. While pursuing the ride comfort of the vehicle, it is also important to ensure that the unsprung mass dynamic load gain DTL does not damage the road within a reasonable range, and the suspension dynamic travel root mean square value SWS does not affect the safety of the suspension within a reasonable range. Therefore, BA, DTL, and SWS are also used as evaluation indicators of the inertance suspension. The calculation formulas of the three performance indicators are as follows:

[0085] Root mean square value of sprung mass acceleration BA:

[0086]

[0087] Root mean square value of unsprung mass dynamic load DTL:

[0088]

[0089] Root mean square value of suspension dynamic travel SWS:

[0090]

[0091] Where i represents the i-th sample, N represents the total amount of samples, z r represents the road input vertical displacement, k t represents the equivalent spring stiffness of the unsprung mass.

[0092] The three indexes of the sprung mass acceleration gain BA, the unsprung mass dynamic load gain DTL, and the root mean square value of suspension dynamic travel SWS are mutually restrictive, and it is difficult to achieve the optimal at the same time, so a comprehensive index T is set as the total optimization index of the inertial suspension:

[0093] T = a·P spru / sus +b·P spri / spru +c·BA+d·DTL+f·SWS;

[0094] Where a, d, c, d, e, and f are the optimization coefficients of the inertial suspension performance indexes; a = 0.25, b = 0.15, c = 0.3, d = 0.1, and f = 0.2. Different optimization coefficients are selected according to the influence degree and importance of the inertial suspension performance indexes on the inertial suspension performance.

[0095] Step 6: Determine the inertial suspension parameters according to the inertial suspension performance index optimization; fish swarm algorithm, ant colony algorithm, particle swarm algorithm, genetic algorithm, simulated annealing algorithm, and other methods can be used to optimize and select the inertial suspension parameters. The optimization results of the inertial suspension parameters are shown in Table 1:

[0096] Table 1. Optimization results of inertial suspension parameters

[0097]

[0098] Where b min represents the minimum value of the inertance, b max represents the maximum value of the inertance, b mid represents the intermediate value of the inertance, c min represents the minimum value of the damper, c max represents the maximum value of the damper, c mid represents the intermediate value of the damper.

[0099] Step 7: Power flow based semi-active implementation of dynamic inertia suspension control method, including two forms of implementation:

[0100] One is power driven inerter control method semi-active implementation, referred to as PDI (Power Driven Inerter Control):

[0101]

[0102] Where b min represents the minimum value of inerter, b max represents the maximum value of inerter, b mid represents the intermediate value of inerter.

[0103] Another is power driven inerter-damper control method semi-active implementation, referred to as PDID (Power Driven Inerter-Damper Control):

[0104]

[0105] Where b min represents the minimum value of inerter, b max represents the maximum value of inerter, b mid represents the intermediate value of inerter, c min represents the minimum value of damper, c max represents the maximum value of damper, c mid represents the intermediate value of damper.

[0106] To compare the effectiveness of the two forms of semi-active implementation of power flow based dynamic inertia suspension control method in improving the performance of the suspension, a traditional passive suspension, i.e. a "spring-damper" parallel suspension structure, is selected, in which the element parameters of the spring k and the damper c are fixed and unchangeable.

[0107] To further demonstrate the superiority of the semi-active implementation of power flow based dynamic inertia suspension control method, a dynamic inertia passive suspension is further selected, i.e. a dynamic inertia suspension structure as shown in Figure 2 , and an acceleration driven damping control suspension (ADD) based on the "spring-damper" parallel structure is selected as a comparison. The control method of ADD is as follows:

[0108]

[0109] Where c tr1 represents the damping value of the adjustable damper in ADD.

[0110] The performance comparison of the five suspensions is shown in Table 2 and Figure 3 As shown in Table 2, it can be seen that the PDI and PDID have a very obvious improvement in the sprung mass acceleration gain BA, and are superior to the widely-recognized ADD. Although the PDI and PDID have a certain deterioration in the non-sprung mass dynamic load gain DTL and the suspension dynamic travel root mean square SWS compared with the traditional passive suspension and the dynamic inertia passive suspension, they are still within a reasonable range and are still improved compared with the ADD. The PDI and PDID are obviously superior to the traditional passive suspension, the dynamic inertia passive suspension and the ADD in the comprehensive performance, and have a great application space.

[0111] Table 2. Performance improvement comparison of each suspension

[0112]

[0113] The embodiments are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvement, replacement or modification made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A dynamic inertia suspension control method based on power flow, characterized in that, Includes the following steps: Step 1: Establish the dynamic inertia suspension structure and build the dynamic inertia suspension model; Step 2: Calculate the vibration power flowing into the dynamic inertia suspension; Step 3: Select the sprung mass as the object to be isolated; Step 4: Determine the dynamic inertia suspension control method based on power flow; Step 5: Determine the performance indicators and comprehensive indicators of the dynamic inertia suspension; Step 6: Optimize and determine the dynamic inertia suspension parameters based on the dynamic inertia suspension performance indicators; Step 7: Semi-active implementation of the power flow-based dynamic inertia suspension control method; The dynamic inertia suspension structure in step 1 is a dynamic inertia suspension structure in which the damper and the inertia container are connected in series and then in parallel with the spring. The dynamic inertia suspension model in step 1 is such that one end of the dynamic inertia suspension structure is connected to the sprung mass, and the other end of the dynamic inertia suspension structure is connected to the unsprung mass. The unsprung mass is connected to the road surface through the equivalent spring of the unsprung mass. The vibration power P flowing into the dynamic inertia suspension in step 2 sus for: ； Where z1 is the vertical displacement of the unsprung mass. z1 is the vertical velocity of the unsprung mass, and z2 is the vertical displacement of the sprung mass. It is the vertical velocity of the sprung mass. It is the vertical acceleration of the sprung mass. It is the vertical velocity at the connection point between the inertial container and the damper. is the vertical acceleration at the connection point between the inertial container and the damper, k is the suspension spring stiffness, c is the damping coefficient of the damper, and b is the inertial mass coefficient of the inertial container. The dynamic inertia suspension control method in step 4 involves adjusting the parameters of the dynamic inertia suspension components to achieve a certain vertical acceleration of the sprung mass. Approaching 0, that is The vibration power in the spring-loaded mass m2 tends towards 0; When it approaches 0, the vibration power P flowing into the dynamic inertia suspension is further simplified. sus get: ； The dynamic inertia suspension performance indicators in step 5 are as follows: Spring mass - suspension vibration power transmission ratio : ； Spring-Spring Mass Vibration Power Transfer Ratio : ； root mean square value of sprung mass acceleration : ； Root mean square value of unsprung mass dynamic load : ； Root mean square value of suspension travel : ； Where i represents the i-th sample, N represents the total number of samples, and z r k represents the vertical displacement of the road surface. t The equivalent spring stiffness represents the unsprung mass. The comprehensive indicator in step 5 is: ； In the comprehensive index formula, a, b, c, d, and f are the optimization coefficients of each dynamic inertia suspension performance index.

2. The dynamic inertia suspension control method based on power flow according to claim 1, characterized in that, The optimization coefficients are a=0.25, b=0.15, c=0.3, d=0.1, and f=0.

2.

3. The dynamic inertia suspension control method based on power flow according to claim 1, characterized in that, The optimization method in step 6 is any one or a combination of fish swarm algorithm, ant colony algorithm, particle swarm algorithm, genetic algorithm, and simulated annealing algorithm.

4. The dynamic inertia suspension control method based on power flow according to claim 1, characterized in that, The semi-active implementation of the power flow-based dynamic inertia suspension control method in step 7 includes the following two implementation forms: One approach is a semi-active implementation of power-driven inertial capacitance control: ； Where b min This indicates that the inertial mass coefficient of the inertial container takes its minimum value, b max This indicates that the inertial mass coefficient of the inertial container takes the maximum value, b. mid The inertial mass coefficient of the inertial container is taken as the median value; Another approach is a semi-active implementation using a power-driven inertial-capacitive-damped control method: ； Where c min This indicates that the damping coefficient of the damper is at its minimum value, c. max This indicates that the damping coefficient of the damper is at its maximum value, c. mid This indicates that the damping coefficient of the damper is taken as an intermediate value.

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