Longitudinal and vertical synchronous cooperative escape control system and method for full-active suspension electric vehicle

Abstract

The invention relates to a longitudinal and vertical synchronous cooperative escape control system and method for a full-active suspension electric vehicle. Comprising the steps that a suspension actuation module receives an out-of-trouble starting signal, obtains a suspension control target and calculates actuation force; the wheel dynamic load observation module observes and outputs the wheel dynamic load; the wheel dynamic load dynamic stability discrimination module introduces an ideal suspension model and a timing module, compares the wheel dynamic load output by the wheel dynamic load observation module with the ideal wheel dynamic load output by the ideal suspension model, and completes wheel dynamic load dynamic stability discrimination; the delay compensation module completes replacement of a dependent wheel dynamic load state in the driving torque synchronous control module through a characteristic value function; and the driving torque synchronous control module completes output control of the wheel torque based on a fusion controller of model prediction control and sliding mode control. The problem that driving control and the actual wheel state are not synchronous is solved, driving delay in escape control is reduced, and maximum wheel adhesive force utilization is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of vehicle-by-wire intelligent chassis dynamics control, and in particular relates to a longitudinal and vertical synchronous cooperative escape control system and method for a fully active suspension electric vehicle. Background Art

[0002] Vehicles are easily stuck on low-adhesion roads such as snow and sand. Traditional methods of getting a vehicle out of a stuck state usually rely on manual push carts or special equipment for assistance, which is inefficient and cumbersome to operate.

[0003] The fully active suspension electric drive vehicle has the feature of self-adjusting suspension, which makes it possible to develop the vehicle's self-help control. In order to improve the ability of electric drive vehicles to get out of trouble, some automobile manufacturers have developed a method based on the regular vibration of active suspension to achieve vehicle escape from trouble. However, this method usually turns off the original drive anti-skid function of the vehicle. This is because the traditional drive anti-skid function first monitors the slip state of the wheel through the wheel speed sensor, and then prevents slip by suppressing the driving torque. This "slip first and then suppress" strategy will cause a certain deviation between the control of the wheel and the actual state. This deviation will inhibit the ability to get out of trouble, and the trapped vehicle will not be able to get out of trouble when the driving torque should be fully increased, and there will be a delay when it should be reduced, resulting in excessive slip, and finally resulting in low utilization of the driving torque.

[0004] In addition, some manufacturers will combine the electronic differential lock with the vibration escape method based on the active suspension law, lock the low-adhesion wheels, and concentrate the driving force on the high-adhesion wheels. However, this method also has limitations. The locked wheels can no longer use the road adhesion, and the remaining drive wheels will still face the possibility of excessive slip when getting out of trouble. Slipping will destroy the existing adhesion conditions and further increase the risk of getting stuck. Therefore, how to effectively improve the longitudinal and vertical coordination when getting out of trouble and maximize the use of the wheel adhesion conditions is the main problem to be solved in this application. Summary of the invention

[0005] The object of the present invention is to provide a longitudinal and vertical synchronous cooperative escape control system and method for a fully active suspension electric vehicle.

[0006] The technical solution to achieve the purpose of the present invention is: a longitudinal and vertical synchronous cooperative escape control system for a fully active suspension electric vehicle, including a suspension actuation module, a wheel dynamic load observation module, a wheel dynamic load dynamic stability judgment module, a delay compensation module and a drive torque synchronization control module;

[0007] The suspension actuation module receives the escape start signal, obtains the suspension control target according to the acquired vehicle status information, and the target is the sine and cosine wheel dynamic load with fixed amplitude A and frequency F. The actuation force u used to track the target to complete the suspension actuation is calculated according to the suspension control target, and outputs the actuation force u and the amplitude A and frequency F of the target tracked under the actuation force u.

[0008] Wheel dynamic load observation module: The wheel dynamic load F is measured through the vehicle status information and the actuation force u output by the suspension actuation module. zdelay Make observations and output them;

[0009] Wheel dynamic load dynamic stability judgment module: introduces the ideal suspension model and timing module to compare the delayed wheel dynamic load output by the wheel dynamic load observation module The ideal wheel dynamic load F output by the ideal suspension model z , the dynamic stability of the wheel load is determined by calculating the variance of the eigenvalue;

[0010] Delay compensation module: receives the output of the wheel dynamic load dynamic stability judgment module when it is judged to be stable. With F z Signal and corresponding amplitude, frequency, deviation characteristic value, calculation With F z The delay time γ corresponding to the phase difference delay , the wheel dynamic load state dependent on the driving torque synchronization control module is replaced by the eigenvalue function;

[0011] Driving torque synchronization control module: A fusion controller based on model predictive control and sliding mode control completes the output control of wheel torque.

[0012] Further, the following steps are included:

[0013] Step (1): Obtain vehicle status information and determine whether to enter the longitudinal and vertical collaborative escape process;

[0014] Step (2): The suspension actuation module obtains a suspension control target, calculates and outputs the actuation force u for completing the suspension actuation and the amplitude A and frequency F of the corresponding tracking target according to the suspension control target;

[0015] Where A = α min (h u ,h d ), α is the available margin of amplitude, ranging from 0 to 1, h u ,h d They are the upper and lower jump limits of the suspension respectively; k is the equivalent spring stiffness of the vehicle, and m is the mass of the vehicle;

[0016] Step (3): The wheel dynamic load observation module receives the acquired vehicle status information and the actuating force u to realize the wheel dynamic load The observation is simultaneously output to the wheel dynamic load stability judgment module and the driving torque synchronization control module;

[0017] Step (4): The ideal suspension model of the wheel dynamic load dynamic stability judgment module starts timing according to the actuating force u in step (2) and calculates the ideal wheel dynamic load F z ; Extract ideal wheel dynamic load F z Eigenvalues ​​amplitude A, frequency F and offset B in the time domain; extract wheel dynamic load with delay Eigenvalue amplitude A′, frequency F′ and offset B′ in the time domain; calculate the variance value S of amplitude A′, frequency F′ and offset B′ s ′, variance value S s ′ and threshold S s Compare and judge the stability; if it is stable, proceed to step (5) to enter the delay compensation process; if it is unstable, proceed to step (3);

[0018] Step (5): The delay compensation module receives the output when the wheel dynamic load dynamic stability judgment module judges that the wheel dynamic load is stable. With F z Signal and corresponding amplitude, frequency, deviation characteristic value, calculation With F z The delay time γ corresponding to the phase difference delay , for the delay time γ delay Determine stability and output dynamic load status

[0019] Step (6): The drive torque synchronization control module receives the output dynamic load state of step (5) And step (3) wheel dynamic load If the result of step (4) is unstable, the output wheel dynamic load of step (3) is used The observed value is used as the state input and then goes to step (63) to calculate the driving torque T of the driving motor. d , to achieve collaborative escape control; if step (4) is judged to be stable, the output dynamic load state of step (5) is used Replace step (3) wheel dynamic load The observed value is used as the state input and then goes to step (61) to calculate the driving torque T of the driving motor. d , to achieve coordinated escape control;

[0020] Step (7): Determine whether the vehicle is successfully escaped. If so, terminate the longitudinal and vertical coordinated escape process, and the active suspension and drive motor continue to execute normal driving commands; if not, go to step (2) until the escape mode is completed.

[0021] Furthermore, step (4) specifically includes the following steps:

[0022] Step (41): The ideal suspension model of the wheel dynamic load dynamic stability judgment module starts timing according to the actuating force u in step (2) and calculates the ideal wheel dynamic load F z ;

[0023] Step (42): According to the ideal wheel dynamic load F z , using the rolling time window to store the wheel dynamic load F within the time period T z , the offset B is obtained by analysis;

[0024] Step (43): According to the amplitude A and frequency F output by the suspension actuation module and the offset B output by the ideal model, the ideal wheel dynamic load F after dynamic stable vibration is obtained. z :

[0025] F Z =Asin(F·t)+B;

[0026] Where t is time;

[0027] Step (44): The wheel dynamic load dynamic stability determination module receives the wheel dynamic load Then, use the rolling time window to store the Perform eigenvalue analysis to obtain amplitude A′, frequency F′ and offset B′;

[0028] Step (45): Obtain the wheel dynamic load with delay after dynamic stable vibration according to the amplitude A′, frequency F′ and offset B′

[0029]

[0030] Step (46): Calculate the variance value S of each characteristic value of the wheel dynamic load signal within the time period T using the variance formula s ′:

[0031]

[0032] where x i , The variable x of the same type can be A', F' or B', and its subscript i represents the discrete sampling point of the variable x of the same type at the i-th time. is the average value of A′, F′ or B′ in the time period, where n is the total number of sampling points in the time period T;

[0033] Step (47): Substitute the variance value S s ′ and set threshold S sIf the wheel load is smaller than the threshold, the dynamic load is considered to be stable. With F z The signal and the corresponding amplitude, frequency and deviation characteristic values ​​are input into the delay compensation module and then transferred to step (5) to enter the delay compensation process. If it is greater than the threshold, it is considered that the wheel dynamic load is dynamically unstable and then transferred to step (3), that is, the wheel dynamic load output by the wheel dynamic load observation module is used before stabilization. Perform drive control.

[0034] Furthermore, step (5) specifically includes the following steps:

[0035] Step (51): Dynamic load on the wheel with delay and the ideal wheel dynamic load F z Use the rolling time window to store and analyze the phase difference between the two in the time period T′ to obtain the delay time γ delay ;

[0036] Step (52): Calculate the delay time γ in the time period T′ window delay The variance S′ d :

[0037]

[0038] where y i , The variable y of the same type is the delay time γ delay , where the subscript i represents the discrete sampling point of the same type of variable y at the i-th time. is the average value of the delay time in the time period, and n is the total number of sampling points in the time period T′;

[0039] Step (53): Substitute the variance S′ of the delay time d With the set variance threshold S d Compare and judge whether the delay time output is stable. If the variance S′ d Greater than the variance threshold S d , that is, unstable, then go to step (54); if the variance S′ d Less than the variance threshold S d , that is, stable, then go to step (57);

[0040] Step (54): No compensation is made for the delay time, i.e. γ delay =0;

[0041] Step (55): Obtain the dynamic load state according to the amplitude A′, frequency F′ and offset B′ of step (44) for:

[0042]

[0043] Among them, t c represents the delay time compensation term, which is used to further adjust the pre-compensation time that cannot be calculated by this method;

[0044] Step (56): The delay compensation module outputs the dynamic load status The delay compensation process ends and jumps to step (61);

[0045] Step (57): Compensate for the calculated delay time γ delay ;

[0046] Step (58): Using the amplitude A′, frequency F′ and offset B′ obtained in step (44), the dynamic load state is obtained. for:

[0047]

[0048] Step (59): The delay compensation module outputs the dynamic load status The delay compensation process ends and jumps to step (61).

[0049] Further, step (6) includes the following steps:

[0050] Step (61): The suspension vibration makes the wheel dynamic load reach dynamic stability, and the wheel dynamic load state in the control of the driving torque of the driving motor The signal prediction uses the eigenvalue function to replace the explicit method, and the driving torque T of the driving motor d The output is based on the fusion controller implementation:

[0051] The eigenvalue function predicts the wheel dynamic load state as follows:

[0052]

[0053] Where Δt is the sampling step size, is the predicted dynamic load value for the next sampling point at time t, and the delay time γ delay The value of is regulated by step (53);

[0054] T d for:

[0055]

[0056] in, Complete the optimization solution for the model prediction step, The solution is completed by sliding mode switching control;

[0057] Step (62): The longitudinal and vertical coordinated escape process ends, and the process jumps to step (7);

[0058] Step (63): The suspension vibration does not make the wheel dynamic load reach dynamic stability, and the state signal of the fusion controller is used to predict the wheel dynamic load state using an explicit method. After completing the prediction step, update the state and obtain the driving torque T of the driving motor under the corresponding state. d ,in It is expressed as:

[0059]

[0060] Where Δt is the sampling step size, is the predicted dynamic load value for the next sampling point at time t;

[0061] T d It is expressed as:

[0062]

[0063] in, Complete the optimization solution for the model prediction step, The solution is completed by sliding mode switching control;

[0064] Step (64): The longitudinal and vertical coordinated escape control process ends and jumps to step (7).

[0065] Furthermore, the driving motor torque T d The calculation of is as follows:

[0066] The discrete sliding surface S in sliding mode control is calculated by model predictive control. t The prediction of As part of the control output; the sliding surface S t for:

[0067]

[0068] e t =λ t -λ d ,

[0069] where e t is the actual slip rate λ at time t t and the target slip ratio λ d The error between them, η is the gain coefficient, and n is the size of the integral window after discretization. The wheel slip rate λ is discretized by implicit Euler method, and the semi-implicit state transfer equation predicted by the model is inversely solved as follows:

[0070]

[0071] Among them, ·τ is the relevant parameter of the controlled wheel; m is the mass of the vehicle in kg; r is the wheel radius in m; I is the moment of inertia of the wheel in kg·m; ω is the wheel speed in rad / s. The wheel angular velocity at the next moment is solved by the explicit Euler method. F xij ,ij∈{fl,fr,rl,rr} are the longitudinal forces N of the left front wheel, right front wheel, left rear wheel and right rear wheel respectively. The Dugoff tire model is used to solve F x , F x =f(F z ,C x ,μ,λ);

[0072] Solution optimization function J completed The solution:

[0073]

[0074] st

[0075] |Δu(t)|≤Δu(t) max

[0076] T min ≤u(t)≤T max

[0077] in, It is represented by the controlled motor at time t Input; P is the penalty factor of the sliding surface, Q is the penalty factor of the motor drive torque change degree, E is the penalty factor of the motor drive torque change degree; Δu(t) max , T min , T max Determined by the characteristics of the drive motor;

[0078] in, The input is obtained by the following formula:

[0079]

[0080] Among them, ε is the switching condition boundary layer thickness, k>0 is the gain coefficient;

[0081] The final driving torque control is:

[0082]

[0083] Compared with the prior art, the present invention has the following significant advantages:

[0084] 1. The longitudinal and vertical coordinated escape control method proposed in the present invention introduces an ideal suspension model in the driving torque controller as a delay comparison object of the wheel vertical load state signal; when it is observed that the wheel dynamic load changes according to a certain rule, the introduced ideal model can replace the wheel dynamic load signal in the state observer in the original control loop, and the delay between the actuator and the state observation part in the control loop can be calculated by calculating the phase difference between the ideal model and the regular dynamic load signal obtained by observation; the ideal model comparison compensation mechanism also introduces an empirically adjustable delay time item, which can realize empirical compensation for the delay introduced by the controller calculation.

[0085] 2. The compensation mechanism based on the ideal suspension dynamic load model proposed in the present invention is specifically divided into two layers; when the conditions of the first layer are met, the ideal suspension model can replace the original dynamic load observer. This layer introduces an adjustable item for empirical compensation of the controller calculation delay time, which can reduce the delay problem caused by the control calculation; the second layer is executed when the conditions of the first layer are met and the delay compensation time output of the calculated phase difference tends to be stable. In the second layer, the delay time caused by the sensor measurement processing and the actuator response in the control loop can be further compensated to achieve high synchronization control.

[0086] 3. The present invention designs a semi-implicit state transfer equation combined with the ideal model control input in the longitudinal and vertical coordinated driving torque control, which is specifically expressed as follows: the transfer equation of the controlled wheel slip rate is solved in an implicit way, and some of the states are realized in an explicit way. The ideal model output is the vertical dynamic load of the wheel after delay compensation, which can be used to calculate the wheel slip rate after conversion through the tire model, which is specifically calculated by the following formula:

[0087]

[0088] This equation can realize the state transfer expression of the wheel slip rate. Even if the compensation mechanism mentioned above does not participate in the compensation, the vertical load can still be used to input the state of the wheel slip rate state transfer equation in an explicit way, and a certain degree of synchronization control can still be achieved.

[0089] 4. The longitudinal and vertical collaborative escape control proposed in the present invention provides a specific method that combines model predictive control with sliding mode control. This fusion method has the advantages of both the predictability of model predictive control and the high robustness of sliding mode control, and the stability of the final controller is still determined by the sliding mode controller. Compared with traditional predictive sliding mode control, the fusion method given in this patent predicts the sliding surface by model prediction, and completes the solution of the equivalent control law in the sliding mode control law by optimization solution; the switching law in the sliding mode control still plays a role in robustness and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 This is a flow chart of the escape control method for this application;

[0091] Figure 2 This is the vertical and vertical collaborative escape flow chart for this application;

[0092] Figure 3 A flowchart of delay compensation for this application;

[0093] Figure 4 This is the driving slip rate control effect diagram under the cooperative control escape control obtained in this application;

[0094] Figure 5 This is a comparison diagram of the synchronization between the wheel dynamic load and the driving torque obtained in this application. DETAILED DESCRIPTION

[0095] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0096] The present application provides a method for coordinated escape control of longitudinal and vertical synchronization for fully active suspension electric drive vehicles. It mainly realizes more effective longitudinal and vertical coordination by "same frequency" output control of the driving torque of the driving motor after the active suspension produces regular vibrations to increase the dynamic load of the wheels, overcomes the problem of asynchronism between the driving control and the actual wheel state, reduces the driving delay in the escape control, and realizes maximum wheel adhesion utilization.

[0097] The above-mentioned longitudinal and vertical coordinated control escape method of the present application is achieved through the following technical solutions:

[0098] S1.0: If Figure 1 Obtain vehicle status information, and detect whether the longitudinal acceleration and speed of the vehicle are continuously zero or close to zero based on the vehicle status information, and whether the wheel speed is high to determine whether the vehicle is stuck; if the vehicle is stuck, a longitudinal and vertical coordinated escape start signal is generated and the longitudinal and vertical coordinated escape process is entered to the next step S2.0; otherwise, if the vehicle is not stuck, no escape start signal is generated and the longitudinal and vertical coordinated escape process is not entered, and the control of the active suspension and the drive motor under normal conditions is continued;

[0099] The longitudinal and vertical coordinated escape process of the present invention is specifically composed of a suspension actuation module, a wheel dynamic load observation module, a wheel dynamic load dynamic stability judgment module, a delay compensation module and a drive torque synchronization control module.

[0100] Specifically, the suspension actuation module receives the escape start signal, and obtains the suspension control target according to the acquired vehicle state information, which is expressed as a sine and cosine wheel dynamic load with a fixed amplitude A and frequency F. According to the control target in the module, the actuation force u for completing the suspension actuation and the amplitude A and frequency F of the corresponding tracking target are calculated and output;

[0101] Wheel dynamic load observation module: mainly through the vehicle status information and the force u, it can realize the wheel dynamic load F zdelay Observation and output.

[0102] Wheel dynamic load dynamic stability judgment module: Its main function is to analyze the F with delay characteristics output by the wheel dynamic load observation module. zdelay , compared with the F without delay characteristic introduced into the ideal suspension model output z , can realize the analysis of the characteristic values ​​of each periodic signal, can complete the dynamic stability judgment of the wheel dynamic load by calculating the variance of each characteristic value, and also has a timing function. Only when it is dynamically stable, will it be further With F z The corresponding amplitude, frequency and deviation characteristic values ​​enter the delay compensation module, and the delay compensation module can deal with the signal delay problem to achieve longitudinal and vertical coordinated escape control.

[0103] The ideal model of active suspension introduced in it can realize the dynamic load F of the wheel. z The output equation is:

[0104]

[0105] Among them, m s ,m t are the sprung mass and unsprung mass kg respectively; K s ,K t are the suspension spring stiffness coefficient and tire stiffness coefficient N / m respectively; C s is the suspension damping coefficient N / (m / s); F s is the force N generated by the active suspension actuator; Z s ,Z t ,Z r are the vertical displacements m of the sprung mass, unsprung mass and ground input respectively; g is the acceleration of gravity m / s 2 . In steady state, it can output the deviation of periodic eigenvalue B.

[0106] Delay compensation module: mainly receives the output from the wheel dynamic load dynamic stability judgment module when it is judged to be stable. With F z Signal and corresponding amplitude, frequency and deviation characteristic values, to calculate With F z The delay time γ corresponding to the phase difference delay , and also has the ability to judge γ delay The stability of γ delay Output function. It can also be realized by using amplitude, frequency and deviation characteristic value and γ delayThe eigenvalue function represented by etc. completes the replacement of the wheel dynamic load state that the driving torque synchronization control module relies on.

[0107] Driving torque synchronization control module: A fusion controller based on model predictive control and sliding mode control completes the output control of wheel torque.

[0108] S2.0: Input of vertical and longitudinal coordinated escape start signal. The specific process is as follows: Figure 2 The suspension actuation module receives the escape start signal, obtains the suspension control target according to the acquired vehicle status information, and the target is expressed as a sine and cosine wheel dynamic load with a fixed amplitude A and frequency F. The actuation force u for completing the suspension actuation and the amplitude A and frequency F of the corresponding tracking target are calculated and output according to the control target in the module; the output signal of the suspension actuation module is simultaneously input into the wheel dynamic load dynamic stability judgment module and the wheel dynamic load observation module;

[0109] In this patent, A=α·min(h u ,h d ), α is the available margin of amplitude, ranging from 0 to 1, and h u ,h d are the suspension upward jump limit and downward jump limit m respectively; k is the equivalent spring stiffness of the vehicle in N / m, and m is the mass of the vehicle in kg;

[0110] S3.0: The wheel dynamic load observation module receives the vehicle status information and the actuating force u to realize the wheel dynamic load The observation is output to the wheel dynamic load dynamic stability judgment module, that is, it goes to step S4.0 and the drive torque synchronization control module, that is, it is output to S6.2; the output to S6.2 is mainly used when the wheel dynamic load is obtained. When the wheel dynamic load dynamic stability judgment module fails to judge it as stable (the default judgment result is unstable), it is still necessary to use the wheel dynamic load with relatively high delay output by the wheel dynamic load observation module. Complete the control of driving torque;

[0111] S4.0: The wheel dynamic load dynamic stability judgment module receives the amplitude A, frequency F and actuation force u output by the suspension actuation module and the wheel dynamic load output by the wheel dynamic load observation module. And start the timing as t, and perform the following steps:

[0112] The timing function is only activated when the actuation force u output by the suspension actuation module is received;

[0113] S4.1: Further, the received actuating force u is input into the ideal model of the active suspension to obtain the ideal wheel dynamic load F zThe rolling time window is used to store the wheel dynamic load F within a period of time T. z , and the offset B is obtained by analysis. The time window size contains at least 3 cycles of the measured signal, that is, T≥3 / F;

[0114] S4.2: Then, the received amplitude A, frequency F and offset B information obtained by analysis are extracted and stored. According to the amplitude A and frequency F output by the suspension actuation module and the output of the ideal model, the dynamic load after dynamic stable vibration satisfies the following relationship:

[0115] F Z =Asin(F·t)+B; (2)

[0116] S4.3: Obtain the wheel dynamic load received by the wheel dynamic stability judgment module Then, a rolling time window is used to store the T in a period of time. Perform eigenvalue analysis to obtain amplitude A′, frequency F′ and offset B′. The time window size should contain at least 3 cycles of the measured signal, that is, T ≥ 3 / F, which should be consistent with T in S4.1;

[0117] S4.4: Then the observed values ​​of the wheel dynamic loads The amplitude A', frequency F' and offset B' information of the periodic characteristic signal are extracted and stored. The dynamic load signal obtained is a delay introduced after a certain calculation process, and the data obtained has delay information in time. The above observer dynamic load relationship can be described as:

[0118]

[0119] S4.5: To ensure that the eigenvalue function is used to replace the wheel dynamic load state output by the wheel dynamic load observation module for driving the torque synchronization control module, its stability must be guaranteed. The variance formula is further used to calculate the variance value S of each eigenvalue of the wheel dynamic load signal. s ′:

[0120]

[0121] where x i , The variable x of the same type can be A', F' or B', and its subscript i represents the discrete sampling point of the variable x of the same type at the i-th time. is the average value of A′, F′ or B′ in the time period, where n is the total number of sampling points in the time period T;

[0122] S4.6: Going a step further, the variance value S s ′ and set threshold S sIf the wheel load is smaller than the ideal threshold, the dynamic load is considered to be stable and With F z The signal and the corresponding amplitude, frequency and deviation characteristic value are input into the delay compensation module and then transferred to step S5.0. If it is greater than the ideal threshold, it is considered that the wheel dynamic load is dynamically unstable and then transferred to step S3.0. That is, before it is stable, the wheel dynamic load output by the wheel dynamic load observation module is used. Perform drive control;

[0123] S5.0: further extract the information stored in S4.2 and S4.4 and transmit it to the delay compensation module, and enter the delay compensation process of the delay compensation module, such as Figure 3 As shown, the specific process is as follows:

[0124] S5.1: The obtained With F z The signal is stored in a rolling time window, and the phase difference between the two signals during this period T′ is analyzed to obtain the corresponding delay time γ delay ; T′ = βΔt in T′ time, Δt is the sampling interval time, that is, β sample points are required;

[0125] S5.2: Further, calculate the variance S′ of the delay time within the time window T′ d , further ensure the stability of the delay compensation time, and avoid excessive or insufficient compensation that may deteriorate the vertical and longitudinal coordination:

[0126]

[0127] where y i , The variable y of the same type is the delay time γ delay , where the subscript i represents the discrete sampling point of the same type of variable y at the i-th time. is the average value of the delay time in the time period, and n is the total number of sampling points in the time period T′;

[0128] S5.3: Further, the variance of the delay time S′ d and set the variance threshold S d Compare and determine whether the delay time output is stable. If it is unstable, that is, the calculated variance value is greater than the set threshold, then go to step S5.4; if it is stable, that is, the calculated variance value is less than the set threshold, then go to step S5.7;

[0129] S5.4: Delay time output is unstable, delay time is not compensated, that is, γ delay =0, no compensation is made to prevent the controlled system from becoming unstable;

[0130] S5.5: Further, the wheel dynamic load is calculated using the periodic signal characteristic value obtained in step S4.4 to obtain the dynamic load state It can be expressed as:

[0131]

[0132] Among them, t c Represents the delay time compensation term, which is used to further adjust the pre-compensation time that cannot be calculated by this method.

[0133] S5.6: Delay compensation module output dynamic load status The delay compensation process ends and jumps to step S6.0;

[0134] S5.7: Delay time output is stable, compensate the calculated delay time γ delay ;

[0135] S5.8: Further, the wheel dynamic load is calculated using the periodic signal characteristic value obtained in step S4.4 to obtain the dynamic load state It can be expressed as:

[0136]

[0137] Where Δt is the sampling step length, t c Represents the delay time empirical compensation term, which is used to further adjust the pre-compensation time that cannot be calculated by this method.

[0138] S5.9: Delay compensation module output dynamic load status The delay compensation process ends and jumps to step S6.0;

[0139] S6.0: At this point, the suspension vibration makes the wheel dynamic load reach dynamic stability, and the wheel dynamic load state signal of the drive torque synchronization control module is replaced by the wheel dynamic load observation module input to the delay compensation module input. Specifically, the wheel dynamic load state signal in the control of the drive motor drive torque is replaced. The signal prediction can be replaced by the explicit method using the eigenvalue function. The driving torque T of the driving motor is d The output is realized based on sliding mode predictive control. The specific steps are as follows:

[0140] The eigenvalue function predicts the wheel dynamic load state as follows:

[0141]

[0142] Where Δt is the sampling step size, is the predicted dynamic load value for the next sampling point at time t, and the delay time γ delay The value of is regulated by S5.3;

[0143] T d is represented as:

[0144]

[0145] in, Complete the optimization solution for the model prediction step, The solution is achieved by sliding mode switching control.

[0146] Driving motor torque T d The calculation of is as follows:

[0147] Discrete Sliding Surface in Sliding Mode Control Using Model Predictive Control The prediction of As part of the control output, e t is the actual slip rate λ at time t t and the target slip ratio λ d The error between , η is the gain coefficient, and n is the size of the integral window after discretization. The wheel slip λ is discretized by implicit Euler method, and the semi-implicit state transfer equation predicted by the model is inversely solved as follows:

[0148]

[0149] Among them, ·τ represents the parameters related to the controlled wheel; m is the vehicle mass kg; r is the wheel radius m; I is the wheel moment of inertia kg·m; ω is the wheel speed rad / s, and the wheel angular velocity at the next moment is solved by the explicit Euler method. F xij ,ij∈{fl,fr,rl,rr} are the longitudinal forces N of the left front wheel, right front wheel, left rear wheel and right rear wheel respectively. The Dugoff tire model is used to solve F x , F x =f(F z ,C x ,μ,λ);

[0150] The solution to the optimization function J can be completed The solution:

[0151]

[0152] in, It is represented by the controlled motor at time t Input; P is the penalty factor of the sliding surface, Q is the penalty factor of the motor drive torque change degree, E is the penalty factor of the motor drive torque change degree; Δu(t) max , T min , T max Determined by the characteristics of the drive motor.

[0153] in, The input is obtained by the following formula:

[0154]

[0155] Among them, ε is the switching condition boundary layer thickness, k>0 is the gain coefficient;

[0156] The final driving torque control is:

[0157]

[0158] S6.1: The longitudinal and vertical coordinated escape control sub-process ends and jumps to step S7.0;

[0159] S6.2: The suspension vibration does not make the wheel dynamic load reach dynamic stability. The corresponding fusion controller state signal can only use the explicit method to predict the wheel dynamic load state. After completing the prediction step, update the state and obtain the driving torque T of the driving motor in the corresponding state. d ,in It is expressed as:

[0160]

[0161] in, is the predicted dynamic load value for the next sampling point at time t.

[0162] T d is represented as:

[0163]

[0164] in, Complete the optimization solution for the model prediction step, The solution is achieved by sliding mode switching control.

[0165] S6.3: The longitudinal and vertical coordinated escape control process ends, and the process jumps to step S7.0;

[0166] S7.0: Determine whether the vehicle has successfully escaped based on the vehicle status. If so, end the longitudinal and vertical coordinated escape sub-process, and the active suspension and drive motor continue to execute normal driving commands; if not, go to step S2.0 until the escape is completed.

[0167] The following MATLAB / Simulink-CarSim joint simulation platform constructs the longitudinal and vertical coordinated escape process. The vehicle is stuck in place and enters the longitudinal and vertical coordinated escape mode. The vehicle is set to be driven by a motor with a full active suspension. The drive control delay is 40ms, t cThe experience-adjustable compensation item is set to 0, and the results only show the results related to the left front wheel of the vehicle: active suspension vibration control is intervened at 0 seconds, and drive control is intervened at 0.3 seconds (that is, the longitudinal and vertical coordinated control is officially started). Figure 4 and Figure 5 The “with delay compensation” in the patent refers to the result of the compensation mechanism of the vertical and vertical high synchronization coordinated control given in this patent; the “without delay compensation” refers to the result of the vertical and vertical high synchronization coordinated control without compensation mechanism (i.e., γ delay =0) participates but still uses a semi-implicit method to predict the wheel rotation rate and the fusion controller to control the result; "ordinary drive control" refers to the result obtained by the sliding mode control commonly used in traditional drive anti-skid control;

[0168] The slip rate of the wheels during the vehicle escape process changes as follows: Figure 4 As shown in the figure, under the ordinary drive cooperative control, there is obvious slip and large fluctuation; under the method applied in this paper, even if no compensation is performed, the slip rate is also controlled to a certain extent, at least there will be no excessive slip to cause the road adhesion condition to be destroyed. However, there is a tendency to suppress wheel drive, which is not conducive to getting out of trouble; if compensation is taken (that is, the result under delayed compensation control), it can be seen that at about 1.6s, the state signal observed by the wheel dynamic load observer is replaced by the sinusoidal function of the characteristic value, and the subsequent slip rate is further controlled and is very close to the set target.

[0169] The synchronicity can be determined based on the simulation results. Figure 5 As shown, the simulation results of 1 to 3 seconds are mainly displayed, which show the vertical dynamic load changes under the actual state of the wheel and the drive output under the corresponding control. It can be found that in the initial stage, the three are almost overlapping and there is a delay, but after a period of time, the advantages of predictive control proposed in this article are reflected. Compared with ordinary drive control, the use of predictive control can improve a certain degree of synchronization. At this time, the predictive control actually adopts the key step S5.5 described in the patent application. When the key step S5.8 described in this patent application is completed, the delay compensation is obviously more synchronized with the vertical dynamic load than the one without delay compensation, and the adhesion ability is greater during the longitudinal and vertical coordinated escape control process.

[0170] The above are exemplary embodiments of the present application, and the protection scope of the present application is defined by the claims and their equivalents. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions are only for illustrating the principles of the present invention. The present invention may have various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention to be protected. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A longitudinal and vertical synchronous cooperative escape control system for fully active suspension trams, characterized in that: It includes a suspension actuation module, a wheel dynamic load observation module, a wheel dynamic load dynamic stability judgment module, a delay compensation module and a drive torque synchronization control module; The suspension actuation module receives the escape start signal, obtains the suspension control target according to the acquired vehicle status information, and the target is the sine and cosine wheel dynamic load with fixed amplitude A and frequency F. The actuation force u used to track the target to complete the suspension actuation is calculated according to the suspension control target, and outputs the actuation force u and the amplitude A and frequency F of the target tracked under the actuation force u. Wheel dynamic load observation module: The wheel dynamic load is observed through the vehicle status information and the actuation force u output by the suspension actuation module. Make observations and output them; Wheel dynamic load dynamic stability judgment module: introduces the ideal suspension model and timing module to compare the delayed wheel dynamic load output by the wheel dynamic load observation module The ideal wheel dynamic load F output by the ideal suspension model z , the dynamic stability of the wheel load is determined by calculating the variance of the eigenvalue; Delay compensation module: receives the output of the wheel dynamic load dynamic stability judgment module when it is judged to be stable. With F z Signal and corresponding amplitude, frequency, deviation characteristic value, calculation With F z The delay time γ corresponding to the phase difference delay , the wheel dynamic load state dependent on the driving torque synchronization control module is replaced by the eigenvalue function; Driving torque synchronization control module: A fusion controller based on model predictive control and sliding mode control completes the output control of wheel torque.

2. A control method for performing longitudinal and vertical synchronous coordinated escape based on the system of claim 1, characterized in that: The steps include: Step (1): Obtain vehicle status information and determine whether to enter the longitudinal and vertical collaborative escape process; Step (2): The suspension actuation module obtains a suspension control target, calculates and outputs the actuation force u for completing the suspension actuation and the amplitude A and frequency F of the corresponding tracking target according to the suspension control target; Where A = α min (h u ,h d ), α is the available margin of amplitude, ranging from 0 to 1, h u ,h d They are the upper and lower jump limits of the suspension respectively; k is the equivalent spring stiffness of the vehicle, and m is the mass of the vehicle; Step (3): The wheel dynamic load observation module receives the acquired vehicle status information and the actuating force u to realize the wheel dynamic load The observation is simultaneously output to the wheel dynamic load stability judgment module and the driving torque synchronization control module; Step (4): The ideal suspension model of the wheel dynamic load dynamic stability judgment module starts timing according to the actuating force u in step (2) and calculates the ideal wheel dynamic load F z ; Extract ideal wheel dynamic load F z Eigenvalues ​​amplitude A, frequency F and offset B in the time domain; extract wheel dynamic load with delay Eigenvalue amplitude A′, frequency F′ and offset B′ in the time domain; calculate the variance value S of amplitude A′, frequency F′ and offset B′ s ′, variance value S s ′ and threshold S s Compare and judge the stability; if it is stable, proceed to step (5) to enter the delay compensation process; if it is unstable, proceed to step (3); Step (5): The delay compensation module receives the output when the wheel dynamic load dynamic stability judgment module judges that the wheel dynamic load is stable. With F z Signal and corresponding amplitude, frequency, deviation characteristic value, calculation With F z The delay time γ corresponding to the phase difference delay , for the delay time γ delay Determine stability and output dynamic load status Step (6): The drive torque synchronous control module receives the output dynamic load state of step (5) And step (3) wheel dynamic load If the result of step (4) is unstable, the output wheel dynamic load of step (3) is used The observed value is used as the state input to calculate the driving torque T of the driving motor. d , to achieve collaborative escape control; if step (4) is judged to be stable, the output dynamic load state of step (5) is used Replace step (3) wheel dynamic load The observed value is used as the state input to calculate the driving torque T of the driving motor. d , to achieve coordinated escape control; Step (7): Determine whether the vehicle is successfully escaped. If so, terminate the longitudinal and vertical coordinated escape process, and the active suspension and drive motor continue to execute normal driving commands; if not, go to step (2) until the escape mode is completed.

3. The method according to claim 2, characterized in that Step (4) specifically includes the following steps: Step (41): The ideal suspension model of the wheel dynamic load dynamic stability judgment module starts timing according to the actuating force u in step (2) and calculates the ideal wheel dynamic load F z ; Step (42): According to the ideal wheel dynamic load F z , using the rolling time window to store the wheel dynamic load F within the time period T z , the offset B is obtained by analysis; Step (43): According to the amplitude A and frequency F output by the suspension actuation module and the offset B output by the ideal model, the ideal wheel dynamic load F after dynamic stable vibration is obtained. z : F Z =Asin(F·t)+B; Where t is time; Step (44): The wheel dynamic load dynamic stability determination module receives the wheel dynamic load Then, use the rolling time window to store the Perform eigenvalue analysis to obtain amplitude A′, frequency F′ and offset B′; Step (45): Obtain the wheel dynamic load with delay after dynamic stable vibration according to the amplitude A′, frequency F′ and offset B′ Step (46): Calculate the variance value S of each characteristic value of the wheel dynamic load signal within the time period T using the variance formula s ′: where x i , The variable x of the same type can be A', F' or B', and its subscript i represents the discrete sampling point of the variable x of the same type at the i-th time. is the average value of A′, F′ or B′ in the time period, where n is the total number of sampling points in the time period T; Step (47): Substitute the variance value S s ′ and set threshold S s If the wheel load is smaller than the threshold, the dynamic load is considered to be stable. With F z The signal and the corresponding amplitude, frequency and deviation characteristic values ​​are input into the delay compensation module and then transferred to step (5) to enter the delay compensation process. If it is greater than the threshold, it is considered that the wheel dynamic load is dynamically unstable and then transferred to step (3), that is, the wheel dynamic load output by the wheel dynamic load observation module is used before stabilization. Perform drive control.

4. The method according to claim 3, characterized in that Step (5) specifically includes the following steps: Step (51): Dynamic load on the wheel with delay and the ideal wheel dynamic load F z Use the rolling time window to store and analyze the phase difference between the two in the time period T′ to obtain the delay time γ delay ; Step (52): Calculate the delay time γ in the time period T′ window delay The variance S′ d : where y i , The variable y of the same type is the delay time γ delay , where the subscript i represents the discrete sampling point of the same type of variable y at the i-th time. is the average value of the delay time in the time period, and n is the total number of sampling points in the time period T′; Step (53): Substitute the variance S′ of the delay time d With the set variance threshold S d Compare and judge whether the delay time output is stable. If the variance S′ d Greater than the variance threshold S d , that is, unstable, then go to step (54); if the variance S′ d Less than the variance threshold S d , that is, stable, then go to step (57); Step (54): No compensation is made for the delay time, i.e. γ delay =0; Step (55): Obtain the dynamic load state according to the amplitude A′, frequency F′ and offset B′ of step (44) for: Among them, t c represents the delay time compensation term, which is used to further adjust the pre-compensation time that cannot be calculated by this method; Step (56): The delay compensation module outputs the dynamic load status The delay compensation process ends and jumps to step (61); Step (57): Compensate for the calculated delay time γ delay ; Step (58): Utilize the amplitude A′, frequency F′ and offset B′ obtained in step (44) to obtain the dynamic load state for: Step (59): The delay compensation module outputs the dynamic load status The delay compensation process ends and jumps to step (61).

5. The method according to claim 4, characterized in that Step (6) comprises the following steps: Step (61): The suspension vibration makes the wheel dynamic load reach dynamic stability, and the wheel dynamic load state in the control of the driving torque of the driving motor The signal prediction uses the eigenvalue function to replace the explicit method, and the driving torque T of the driving motor d The output is based on the fusion controller implementation: The eigenvalue function predicts the wheel dynamic load state as follows: Where Δt is the sampling step size, is the predicted dynamic load value for the next sampling point at time t, and the delay time γ delay The value of is regulated by step (53); T d for: in, Complete the optimization solution for the model prediction step, The solution is completed by sliding mode switching control; Step (62): The longitudinal and vertical coordinated escape process ends, and the process jumps to step (7); Step (63): The suspension vibration does not make the wheel dynamic load reach dynamic stability, and the state signal of the fusion controller is used to predict the wheel dynamic load state using an explicit method. After completing the prediction step, update the state and obtain the driving torque T of the driving motor under the corresponding state. d ,in It is expressed as: Where Δt is the sampling step size, is the predicted dynamic load value for the next sampling point at time t; T d It is expressed as: in, Complete the optimization solution for the model prediction step, The solution is completed by sliding mode switching control; Step (64): The longitudinal and vertical coordinated escape control process ends and jumps to step (7).

6. The method according to claim 5, characterized in that Driving motor torque T d The calculation of is as follows: The discrete sliding surface S in sliding mode control is calculated by model predictive control. t The prediction of As part of the control output; the sliding surface S t for: e t =λ t -l d , where e t is the actual slip rate λ at time t t and the target slip ratio λ d The error between them, η is the gain coefficient, and n is the size of the integral window after discretization. The wheel slip rate λ is discretized by implicit Euler method, and the semi-implicit state transfer equation predicted by the model is inversely solved as follows: in,· τ are the parameters related to the controlled wheel; m is the vehicle mass kg; r is the wheel radius m; I is the wheel moment of inertia kg·m; ω is the wheel speed rad / s. The wheel angular velocity at the next moment is solved by the explicit Euler method. F xij ,ij∈{fl,fr,rl,rr} are the longitudinal forces N of the left front wheel, right front wheel, left rear wheel and right rear wheel respectively. The Dugoff tire model is used to solve F x , F x =f(F z ,C x ,μ,λ); Optimization function J completed The solution: st |Δu(t)|≤Δu(t) max T min ≤u(t)≤T max in, It is represented by the controlled motor at time t Input; P is the penalty factor of the sliding surface, Q is the penalty factor of the motor drive torque change degree, E is the penalty factor of the motor drive torque change degree; Δu(t) max , T min , T max Determined by the characteristics of the drive motor; in, The input is obtained by the following formula: Among them, ε is the switching condition boundary layer thickness, k>0 is the gain coefficient; The final driving torque control is:

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