Design method of asynchronous observer for CDC semi-active suspension with variable vehicle speed

Abstract

This paper presents a design method for an asynchronous observer of a CDC semi-active suspension system applicable to vehicle speed variations, relating to the field of semi-active suspension state estimation technology. The additional dynamic force generated by the vehicle's non-uniform speed travel on the suspension system serves as the external input. The suspension extension / retraction speed is used as a switching signal, and a piecewise model of the suspension system is provided to describe the nonlinear behavior of the CDC damper and the asymmetry of damping force during compression and rebound strokes. The piecewise nonlinear CDC semi-active suspension model is subjected to T-S fuzzification processing. The suspension extension / retraction speed signal is obtained by converting data from onboard acceleration sensors, and an asynchronous observer is designed to ensure estimation stability and output accuracy when the observer and the suspension system are in different zones due to errors in acquiring the suspension extension / retraction speed signal. Based on a dual accelerometer sensor configuration and fully considering the nonlinear characteristics of the CDC damper, the vibration state of the suspension system can be estimated more stably and accurately.

Description

Technical Field

[0001] This invention relates to the field of semi-active suspension state estimation technology, specifically to a design method for asynchronous observers of CDC semi-active suspension applicable to vehicle speed changes. Background Technology

[0002] In practical engineering, due to cost considerations and installation limitations, the available measurement signals for suspension systems typically only include suspension displacement and the acceleration of sprung and unsprung masses. Obtaining data on vehicle and tire speeds, suspension displacement velocities, and dynamic tire forces is usually impractical. Therefore, it becomes crucial to use estimation techniques to derive the necessary system states from measurable data, thereby providing accurate and reliable state estimates for the suspension system.

[0003] For semi-active suspension observer design, neglecting the significant nonlinear force characteristics of the damper can severely degrade the estimation quality. Some studies employ Extended Kalman Filters (EKF) and Unscented Kalman Filters (UKF) for observer design, assuming that the system's noise and probability density functions follow a Gaussian distribution, which is not always true in real-world systems. Other studies treat the damping force as a dummy control variable, allowing nonlinear semi-active suspension systems to be approximated as linear systems for observer design. However, obtaining the damping force in semi-active suspensions typically relies on signals such as suspension speed, which cannot be directly obtained from sensors. Furthermore, observers using neural network methods offer an alternative independent of model dependencies, but their accuracy depends on acquiring large amounts of training data, which may not always be readily available.

[0004] In summary, due to the complexity of actual vehicle driving conditions and the variability of speed, developing a vehicle suspension state estimation method that can adapt to changes in vehicle speed is of significant engineering importance. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a design method for an asynchronous observer of a CDC semi-active suspension suitable for vehicle speed variations. Based on a dual accelerometer sensor configuration commonly used in engineering, and taking full account of the nonlinear characteristics of the CDC damper, it can more stably and accurately estimate the vibration state of the suspension system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a design method for an asynchronous observer of a CDC semi-active suspension applicable to vehicle speed variations, comprising the following steps:

[0007] Step 1: Treat the additional dynamic force generated by the vehicle's non-uniform speed travel on the suspension system as the external input to the suspension system;

[0008] By balancing the torques at the contact points of the front and rear tires, we obtain the expressions for the vertical loads on the front and rear axles at the current moment. We then subtract these expressions from the nominal loads on the front and rear axles to obtain the longitudinal acceleration 'a' of the vehicle at different times. x Load transfer at each suspension point Where, the superscript i = f and r represent the front axle and the rear axle respectively, and m = l and r represent the left suspension and the right suspension respectively;

[0009] Step 2: Using the suspension extension / retraction speed as the switching signal, a segmented model of the suspension system is given to describe the nonlinear behavior of the CDC damper and the phenomenon of damping force asymmetry in the compression and rebound strokes;

[0010] Using suspension extension / retraction speed As a switching signal, the external characteristics of the CDC damper are divided into three segments: Where R α This indicates that the suspension system is currently in the α-th partition, where α = 1, 2, 3 is the system partition index, and F d The damping force of the CDC damper:

[0011] For α = 1, 3,

[0012] For α = 2,

[0013] Where I is the driving current of the damper, b α c α d α e α f α g α h α p α The parameters obtained for identification;

[0014] Using the additional dynamic force model as the external input to the suspension system, we obtain a quarter-CDC semi-active suspension dynamic model considering the additional dynamic force, and select the system state variables. System disturbance Control quantity u = I des , where z s and z u Vertical displacements of the sprung mass and unsprung mass, respectively, z r For the elevation information input for the road surface, I des To control the input, a piecewise nonlinear CDC semi-active suspension model is established as follows:

[0015]

[0016] in,

[0017]

[0018] B1 = [0 0 1 0 0] T ,

[0019] J α (I)=f α I 2 +g α I+h α F α (I)=c s +b α I 3 +c α I 2 +d α I+e α

[0020] In the formula, m s For the suspension sprung mass, m u For the unsprung mass of the suspension, k s For the spring stiffness, k t Let d be the vertical stiffness of the tire, and d be the time constant.

[0021] Step 3: Perform TS fuzzification on the piecewise nonlinear CDC semi-active suspension model;

[0022] Select Z α,1 =F α (I) and Z α,2 =J α (I) represents the antecedent variable. The piecewise nonlinear CDC semi-active suspension model is characterized by the following switching TS model:

[0023]

[0024] In the formula, ξ α Let δ be the number of TS subsystems in the α-th partition of the suspension system. α (x) is the switching signal for the suspension system, h αj (Z) represents the weight of the j-th TS subsystem in the α-th partition of the suspension system, A αj Let be the coefficient matrix of the j-th TS subsystem in the α-th partition of the suspension system;

[0025] Step 4: Calculate and obtain the suspension extension speed signal based on the data from the vehicle acceleration sensor, and design an asynchronous observer to ensure the estimation stability and output accuracy when the observer and the suspension system are in different zones due to errors in obtaining the suspension extension speed signal.

[0026] The measurement output equation of the suspension system is:

[0027]

[0028] in,

[0029] The measurement output, after being fuzzified by TS, is represented as follows:

[0030]

[0031] In the formula, C αj This is the output matrix of the j-th TS subsystem in the α-th partition of the suspension system;

[0032] Discretize the suspension system as follows:

[0033]

[0034]

[0035] Design the asynchronous observer as follows:

[0036]

[0037] In the formula, This is the switching signal for the observer. For observer partition indexing, For the observer The weights of the p-th TS sub-observer in each partition For the observer The coefficient matrix of the p-th TS subsystem in each partition For the observer The output matrix of the p-th TS subsystem in each partition For the observer's estimated value, For the observer's output value, This indicates that the observer is currently at the [current position]. One partition, For the observer The number of TS sub-observers in each partition, For observer gain;

[0038] Define Ω as the set of all possible state transition pairs of the suspension system, Ω = {(α,β)|x k ∈R α ,x k+1 ∈R β}, R β This represents the suspension system being in the β-th partition at the next moment, where β = 1, 2, 3; (Definition) The set of all possible state transition pairs for the observer. This indicates that the observer will be at the next moment. One partition,

[0039] Define the observer error as have:

[0040]

[0041] In the formula, For the observer The output matrix of the s-th TS sub-observer in each partition;

[0042] definition have:

[0043]

[0044] in,

[0045] When α = 1, 3, the domain of the suspension system is:

[0046]

[0047] when At that time, the domain of the observer is:

[0048]

[0049] in,

[0050] The design goal of asynchronous observers is to design If a matrix exists and scalar If r > 0, then the following optimization problem has a solution:

[0051] min r

[0052] Case 1, α = 1, 3

[0053]

[0054] in,

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] Case 2, α = 2,

[0065] In the inequality of case 1, g 14 g 22 g 24 and g 44 In f α a α and d α Set to 0;

[0066] Case 3, α = 1, 3

[0067] In the inequality of case 1, g 14 g 22 g 24 and g 44 In and Set to 0;

[0068] Case 4, α = 2,

[0069]

[0070] The observer gain is then expressed as

[0071] Furthermore, the expressions for the vertical loads on the front and rear axles at the current moment in step one are as follows:

[0072]

[0073] In the formula, This indicates the vertical load on the front axle. The vertical load on the rear axle is represented by M, the vehicle mass is represented by g, and the acceleration due to gravity is represented by l. f and l r h represents the distance from the center of gravity to the front and rear axles, respectively. g F represents the height of the center of gravity. w h represents wind resistance. w This indicates the equivalent height of the point of action of wind resistance.

[0074] Furthermore, the quarter-CDC semi-active suspension dynamic model considering additional dynamic forces in step two is as follows:

[0075]

[0076]

[0077]

[0078] In the formula, c s This is the passive damping coefficient.

[0079] Furthermore, in step three, the antecedent variable Z... α,1 and Z α,2 They are represented as follows:

[0080]

[0081] Among them, M α,1 and M α,2 and N α,1 and N α,2 The membership function is defined as follows:

[0082]

[0083]

[0084] In the formula, and Z α,1 The maximum and minimum values, and Z α,2 The maximum and minimum values.

[0085] Furthermore, the design goal of the asynchronous observer in step four... It should make Meanwhile, external disturbances To z k The gain satisfies:

[0086]

[0087] Where r is To z k L2 gain.

[0088] Compared with the prior art, the beneficial effects of the present invention are:

[0089] 1. The asynchronous observer of this invention is applicable to the problem of estimating the suspension vibration state under uniform and non-uniform vehicle operating conditions, thus expanding the applicability of the observer to various operating conditions;

[0090] 2. The asynchronous observer of this invention is designed with the nonlinear characteristics of the CDC damper in mind, which can ensure the estimation stability and output accuracy of the observer even when the suspension extension speed signal is not accurately obtained. Attached Figure Description

[0091] Figure 1 This is a schematic diagram of a vehicle model for non-uniform speed driving conditions in the method of the present invention;

[0092] Figure 2 This is a schematic diagram of the three-segment partitioning of the external characteristics of the CDC damper in the method of this invention;

[0093] Figure 3 This is a comparison chart of the output results of the two observers in the embodiment when the vehicle passes over a speed bump;

[0094] Figure 4 This is a comparison chart of the output results of the asynchronous observer in the embodiment under the condition of vehicle acceleration and deceleration on flat ground. Detailed Implementation

[0095] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0096] like Figures 1-2 As shown, the design method for the asynchronous observer of the CDC semi-active suspension applicable to vehicle speed variations includes the following steps:

[0097] Step 1: Treat the additional dynamic force generated by the vehicle's non-uniform speed travel on the suspension system as an external input to the suspension system, as follows:

[0098] Combination Figure 1 As shown, for a vehicle traveling at a non-uniform speed, taking the torque balance at the contact points of its front and rear tires, the expressions for the vertical loads on the front and rear axles at the current moment can be obtained as follows:

[0099]

[0100] In the formula, This indicates the vertical load on the front axle. The vertical load on the rear axle is represented by M, the vehicle mass is represented by g, and the acceleration due to gravity is represented by l. f and l r These represent the distances from the center of gravity to the front and rear axles, respectively. x h represents the longitudinal acceleration of the vehicle. g F represents the height of the center of gravity. w h represents wind resistance.w This indicates the equivalent height of the point of action of wind resistance.

[0101] Then, respectively through the nominal load of the front axle and rear axle nominal load Differentials yield different values ​​of a x Load transfer at each suspension point Where the superscripts i = f and r represent the front axle and rear axle respectively, and m = l and r represent the left and right suspensions respectively. Therefore, the load transfer amount of the left suspension of the front axle... and load transfer of the right front axle suspension Possible values Rear axle left suspension load transfer and load transfer of the right rear axle suspension Possible values and These represent the load transfer amounts at the front axle and rear axle, respectively.

[0102] Step 2: Using the suspension extension / retraction speed as the switching signal, a piecewise model of the suspension system is provided to describe the nonlinear behavior of the CDC damper and the phenomenon of damping force asymmetry during compression and rebound strokes, as detailed below:

[0103] Combination Figure 2 As shown, the suspension extension / retraction speed is used. As a switching signal, the external characteristics of the CDC damper are divided into three segments: Where R α This indicates that the suspension system is currently in the α-th partition, where α = 1, 2, 3 is the system partition index, and F d Let be the damping force of the CDC damper. In each partition, a fit is performed based on experimental data; for α = 1, 3, the expression for the damping force is: Where I is the driving current of the damper, b α c α d α e α f α g α h α p α To identify the parameters, due to the characteristic of the damping force passing through the origin, we have f α =g α =h α =p α =0, therefore, for α=2, the expression for the damping force is:

[0104] Combination Figure 1As shown, by using the additional dynamic force model as the external input to the suspension system, the dynamic model of the quarter-CDC semi-active suspension considering the additional dynamic force can be obtained as follows:

[0105]

[0106]

[0107]

[0108] In the formula, m s For the suspension sprung mass, m u For the unsprung mass of the suspension, k s For the spring stiffness, c s k is the passive damping coefficient. t For the vertical stiffness of the tire, z s and z u Vertical displacements of the sprung mass and unsprung mass, respectively, z r For the elevation information input for the road surface, I des To control the input, d is the time constant.

[0109] By selecting the system state variables as System disturbance Control quantity u = I des The piecewise nonlinear CDC semi-active suspension model is established as follows:

[0110]

[0111] in,

[0112]

[0113] B1 = [0 0 1 0 0] T ,

[0114] J α (I)=f α I 2 +g α I+h α F α (I)=c s +b α I 3 +c α I 2 +d α I+e α ;

[0115] Step 3: Perform TS fuzzification on the piecewise nonlinear CDC semi-active suspension model, as follows:

[0116] Select Z α,1 =F α (I) and Z α,2 =J α (I) is the antecedent variable, Z α,1 The maximum and minimum values ​​are respectively and but Z α,2 The maximum and minimum values ​​are respectively and but The preceding variable Z α,1 and Z α,2 They are represented as follows:

[0117]

[0118] Among them, M α,1 and M α,2 and N α,1 and N α,2 The membership function is defined as follows:

[0119]

[0120]

[0121] Furthermore, the piecewise nonlinear CDC semi-active suspension model can be characterized by the following switching TS model:

[0122]

[0123] In the formula, ξ α Let δ be the number of TS subsystems in the α-th partition of the suspension system. α (x) is the switching signal for the suspension system, determined by the suspension extension / retraction speed. Decision, h αj (Z) represents the weight of the j-th TS subsystem in the α-th partition of the suspension system, A αj Let be the coefficient matrix of the j-th TS subsystem in the α-th partition of the suspension system;

[0124] Step 4: Calculate and obtain the suspension extension / detension speed signal based on the onboard acceleration sensor data. Design an asynchronous observer to ensure estimation stability and output accuracy when the observer and suspension system are in different zones due to errors in acquiring the suspension extension / detension speed signal. Details are as follows:

[0125] Dual accelerometer setups are widely used in engineering practice due to their low cost and ease of installation. Sprout and unsprung mass vibration acceleration sensors are selected as the measurement output. Furthermore, the suspension controller can read and adjust the drive current of the CDC damper in real time to achieve the desired value. Therefore, the measurement output equation of the suspension system is:

[0126]

[0127] in,

[0128] The measurement output, after being fuzzified by TS, is represented as follows:

[0129]

[0130] In the formula, C αj Let be the output matrix of the j-th TS subsystem in the α-th partition of the suspension system.

[0131] Discretize the suspension system as follows:

[0132]

[0133]

[0134] In the formula, Let J be the coefficient matrix of the j-th discrete TS subsystem in the α-th partition of the suspension system. Let be the output matrix of the j-th discrete TS subsystem in the α-th partition of the suspension system.

[0135] Design the asynchronous observer as follows:

[0136]

[0137] In the formula, This is the switching signal for the observer. For observer partition indexing, For the observer The weights of the p-th TS sub-observer in each partition For the observer The coefficient matrix of the p-th TS subsystem in each partition For the observer The output matrix of the p-th TS subsystem in each partition For the observer's estimated value, For the observer's output value, This indicates that the observer is currently at the [current position]. One partition, For the observer The number of TS sub-observers in each partition, This is the observer gain.

[0138] Define Ω as the set of all possible state transition pairs of the suspension system, Ω = {(α,β)|x k ∈R α ,x k+1 ∈R β}, where R β This represents the suspension system being in the β-th partition at the next moment, where β = 1, 2, 3; (Definition) The set of all possible state transition pairs for the observer. in, This indicates that the observer will be at the next moment. One partition,

[0139] Define the observer error as have:

[0140]

[0141] In the formula, For the observer The output matrix of the s-th TS sub-observer in each partition.

[0142] definition have:

[0143]

[0144] in,

[0145] When α = 1, 3, the domain of the suspension system can be expressed as:

[0146]

[0147] when When the observer's domain is defined, it can be expressed as:

[0148]

[0149] in,

[0150] The design goal of asynchronous observers is to design Make Meanwhile, external disturbances To z k The gain satisfies:

[0151]

[0152] Where r is To z k L2 gain.

[0153] Then, if there exists a matrix and scalar If r > 0, then the following optimization problem has a solution:

[0154] min r

[0155] Case 1, α = 1, 3

[0156]

[0157] in,

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167] Case 2, α = 2, In the inequality of case 1, g 14 g 22 g 24 and g 44 In f α a α and d α Set it to 0; Case 3, α = 1, 3,

[0168] In the inequality of case 1, g 14 g 22 g 24 and g 44 In and Set it to 0; Case 4, α = 2,

[0169]

[0170] The observer gain can then be expressed as

[0171] Example

[0172] In this embodiment, the vehicle underwent acceleration and deceleration operations both over speed bumps and on flat ground during the experiment. Figure 3 A comparison of the outputs of the designed asynchronous observer and the synchronous observer shows that, under the premise of inaccurate switching signal acquisition, the output of the asynchronous observer proposed in this invention is significantly better than that of the synchronous observer. Figure 4 The asynchronous observer outputs considering and not considering additional dynamic forces under vehicle acceleration and deceleration conditions demonstrate that the asynchronous observer proposed in this invention, by considering additional dynamic forces, can improve the estimation accuracy of vehicles under non-uniform speed conditions and expand the applicable conditions of the observer.

[0173] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0174] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A design method for an asynchronous observer of a CDC semi-active suspension applicable to vehicle speed variations, characterized in that: Includes the following steps: Step 1: Treat the additional dynamic force generated by the vehicle's non-uniform speed travel on the suspension system as the external input to the suspension system; By balancing the torques at the contact points of the front and rear tires, we obtain the expressions for the vertical loads on the front and rear axles at the current moment. We then subtract these expressions from the nominal loads on the front and rear axles to obtain the longitudinal acceleration 'a' of the vehicle at different times. x Load transfer at each suspension point Where, the superscript i = f and r represent the front axle and the rear axle respectively, and m = l and r represent the left suspension and the right suspension respectively; Step 2: Using the suspension extension / retraction speed as the switching signal, a segmented model of the suspension system is given to describe the nonlinear behavior of the CDC damper and the phenomenon of damping force asymmetry in the compression and rebound strokes; Using suspension extension / retraction speed As a switching signal, the external characteristics of the CDC damper are divided into three segments: Where R α This indicates that the suspension system is currently in the α-th partition, where α = 1, 2, 3 is the system partition index, and F d The damping force of the CDC damper: For α = 1, 3, For α = 2, Where I is the driving current of the damper, b α c α d α e α f α g α h α p α The parameters obtained for identification; Using the additional dynamic force model as the external input to the suspension system, we obtain a quarter-CDC semi-active suspension dynamic model considering the additional dynamic force, and select the system state variables. System disturbance Control quantity u = I des , where z s and z u Vertical displacements of the sprung mass and unsprung mass, respectively, z r For the elevation information input for the road surface, I des To control the input, a piecewise nonlinear CDC semi-active suspension model is established as follows: in, J α (I)=f α I 2 +g α I+h α ,F α (I)=c s +b α I 3 +c α I 2 +d α I+e α In the formula, m s For the suspension sprung mass, m u For the unsprung mass of the suspension, k s For the spring stiffness, k t Let d be the vertical stiffness of the tire, and d be the time constant. Step 3: Perform TS fuzzification on the piecewise nonlinear CDC semi-active suspension model; Select Z α,1 =F α (I) and Z α,2 =J α (I) represents the antecedent variable. The piecewise nonlinear CDC semi-active suspension model is characterized by the following switching TS model: In the formula, ξ α Let δ be the number of TS subsystems in the α-th partition of the suspension system. α (x) is the switching signal for the suspension system, h αj (Z) represents the weight of the j-th TS subsystem in the α-th partition of the suspension system, A αj Let be the coefficient matrix of the j-th TS subsystem in the α-th partition of the suspension system; Step 4: Calculate and obtain the suspension extension speed signal based on the data from the vehicle acceleration sensor, and design an asynchronous observer to ensure the estimation stability and output accuracy when the observer and the suspension system are in different zones due to errors in obtaining the suspension extension speed signal. The measurement output equation of the suspension system is: in, The measurement output, after being fuzzified by TS, is represented as follows: In the formula, C αj This is the output matrix of the j-th TS subsystem in the α-th partition of the suspension system; Discretize the suspension system as follows: Design the asynchronous observer as follows: In the formula, This is the switching signal for the observer. For observer partition indexing, For the observer The weights of the p-th TS sub-observer in each partition For the observer The coefficient matrix of the p-th TS subsystem in each partition For the observer The output matrix of the p-th TS subsystem in each partition For the observer's estimated value, For the observer's output value, This indicates that the observer is currently at the [current position]. One partition, For the observer The number of TS sub-observers in each partition, For observer gain; Define Ω as the set of all possible state transition pairs of the suspension system, Ω = {(α,β)|x k ∈R α ,x k+1 ∈R β }, R β This represents the suspension system being in the β-th partition at the next moment, where β = 1, 2, 3; (Definition) The set of all possible state transition pairs for the observer. This indicates that the observer will be at the next moment. One partition, Define the observer error as have: In the formula, For the observer The output matrix of the s-th TS sub-observer in each partition; definition have: in, When α = 1, 3, the domain of the suspension system is: when At that time, the domain of the observer is: in, i T =[001-10]; The design goal of asynchronous observers is to design If a matrix exists and scalar If r > 0, then the following optimization problem has a solution: min r Case 1, α = 1, 3 in, Case 2, α = 2, In the inequality of case 1, g 14 g 22 g 24 and g 44 In f α , and Set to 0; Case 3, α = 1, 3, In the inequality of case 1, g 14 g 22 g 24 and g 44 In and Set to 0; Case 4, α = 2, The observer gain is then expressed as 2. The design method for an asynchronous observer of a CDC semi-active suspension applicable to vehicle speed variations according to claim 1, characterized in that: The expressions for the vertical loads on the front and rear axes at the current moment in step one are as follows: In the formula, This indicates the vertical load on the front axle. The vertical load on the rear axle is represented by M, the vehicle mass is represented by g, and the acceleration due to gravity is represented by l. f and l r h represents the distance from the center of gravity to the front and rear axles, respectively. g F represents the height of the center of gravity. w h represents wind resistance. w This indicates the equivalent height of the point of action of wind resistance.

3. The design method for an asynchronous observer of a CDC semi-active suspension applicable to vehicle speed variations according to claim 1, characterized in that: The quarter-CDC semi-active suspension dynamics model considering additional dynamic forces in step two is as follows: In the formula, c s This is the passive damping coefficient.

4. The design method for an asynchronous observer of a CDC semi-active suspension applicable to vehicle speed variations according to claim 1, characterized in that: In step three, the antecedent variable Z α,1 and Z α,2 They are represented as follows: Among them, M α,1 and M α,2 and N α,1 and N α,2 The membership function is defined as follows: In the formula, and Z α,1 The maximum and minimum values, and Z α,2 The maximum and minimum values.

5. The design method for an asynchronous observer of a CDC semi-active suspension applicable to vehicle speed variations according to claim 1, characterized in that: The design goal of the asynchronous observer in step four It should make Meanwhile, external disturbances To z k The gain satisfies: Where r is To z k L2 gain.

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