A body posture compensation active control method and system

Abstract

This invention discloses an active control method for vehicle posture compensation, comprising the following steps: S01, calculating the optimal vertical control force: During vehicle operation, the vertical acceleration of the vehicle's center of gravity and the vertical displacement at the suspension load point are obtained from acceleration and displacement sensors. The state-space equation of the system is constructed based on the motion equations of the seven-degree-of-freedom suspension dynamics model of the whole vehicle. The optimal vertical control force f is solved using a model predictive controller. si S02. Calculate the vehicle attitude control force: During vehicle operation, the pitch angle θ and roll angle φ of the center of gravity are obtained from the three-axis gyroscope and input into the fuzzy controller. S03. Input the target current i into the driver to generate the electromagnetic force required for active suspension using the electromagnetic linear actuator. The active suspension control strategy proposed in this invention uses a linear motor as the actuator, and the force generated is not limited by the relative speed at both ends of the suspension.

Description

Technical Field

[0001] This invention belongs to the field of suspension control, and particularly relates to an active control method and system for vehicle body posture compensation. Background Technology

[0002] Among the many systems in a car, the suspension system has the greatest impact on ride comfort and driving safety. Also known as the car's damping system, its main function is to support the vehicle body, buffer vibrations and impacts transmitted from the road surface, provide a smooth and comfortable environment for passengers, and ensure vehicle safety. Advances in suspension technology have led to the development of car suspensions from passive to semi-active and active modes.

[0003] Because the parameters of each component in a passive suspension system are designed to be fixed values ​​during manufacturing and cannot be dynamically adjusted in real time, active suspension systems have begun to attract attention. Active suspension systems add an active force controller to the passive suspension system, calculating the required ideal active control force to achieve the desired vehicle body control effect.

[0004] When a car is in motion, both driver input and road conditions cause pitch, roll, and vertical movements in the vehicle body. These movements can potentially cause discomfort to passengers, damage to cargo, or even lead to rollovers or injuries. Compared to passive suspension, active suspension technology uses a controller to manage the output of actuators, thereby generating active control forces to suppress vehicle movement. Active suspension can effectively suppress vehicle movement; however, research on balancing stable motion control in all three directions is relatively insufficient when designing active suspension systems. Furthermore, the vertical, pitch, and roll movements of the vehicle body are coupled, making it difficult to control them simultaneously. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a vehicle body attitude compensation active control method and system. The vehicle body attitude compensation control strategy effectively improves the vehicle's vertical motion while also effectively suppressing vehicle body attitude, thus enhancing ride comfort and driving safety. The vehicle body attitude compensation control strategy of this invention includes vehicle vertical control and vehicle attitude control. It calculates active control forces using a model predictive controller to suppress the vertical vibration of sprung mass, and simultaneously calculates vehicle body attitude control forces using a fuzzy control algorithm to suppress pitch and roll vibrations. Relevant state variables in the vehicle system are acquired through accelerometers, displacement sensors, and a three-axis gyroscope, effectively ensuring the control effect of the vehicle body attitude compensation active control strategy.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] An active control method for vehicle body posture compensation includes the following steps:

[0008] S01. Calculate the optimal vertical control force:

[0009] During vehicle operation, the vertical acceleration of the vehicle's center of gravity and the vertical displacement at the suspension load point are obtained from acceleration and displacement sensors. The state-space equation of the system is constructed based on the motion equations of the seven-degree-of-freedom suspension dynamics model of the whole vehicle, and the optimal vertical control force f is solved using a model predictive controller. si .

[0010] S02, Calculate vehicle attitude control force:

[0011] During vehicle operation, the pitch angle θ and roll angle of the center of gravity are obtained from the three-axis gyroscope. The pitch angle θ and the tilt angle of the center of mass The input to the fuzzy controller is used to solve for the vehicle body attitude control force f using a fuzzy algorithm. fi This generates anti-pitch and anti-roll moments to control the vehicle's attitude.

[0012] S03. Calculate the target current required for the electromagnetic linear actuator:

[0013] The optimal vertical control force f si and vehicle body attitude control force Δf ij The summation yields the electromagnetic force F required for suspension control. ti Divide it by the thrust constant K i The target current i is obtained and input into the driver to make the electromagnetic linear actuator generate the electromagnetic force required for active suspension.

[0014] Furthermore, the construction of the system's state-space equations based on the motion equations of the vehicle's seven-degree-of-freedom dynamics model specifically involves:

[0015] The equations of motion for vertical, roll, and pitch at the vehicle's center of gravity are:

[0016]

[0017] Where: m b For the sprung mass of the vehicle; z c B represents the vertical displacement at the vehicle's center of gravity. f B r These are half the track width of the front axle and half the track width of the rear axle, respectively; f l r θ represents the distances from the front and rear wheels to the vehicle's lateral centerline, respectively; θ is the vehicle's pitch angle. This refers to the vehicle body roll angle; I θ These are the moments of inertia of the vehicle body about the x-axis and y-axis, respectively; f i(i = 1, 2, 3, 4, the same below) represents the suspension force;

[0018] The equation for the vertical displacement of the wheel is:

[0019]

[0020] Where: m wi For tire mass; z wi k represents the vertical displacement of each tire. ti For tire stiffness; q i The road surface excitation experienced by each suspension;

[0021] The suspension force can be expressed as:

[0022]

[0023] In the formula: c i Z is the damping coefficient of the shock absorber; si k represents the vertical displacement at each suspension load point. si For suspension spring stiffness; F ti Provides the main power to the suspension for the electromagnetic actuator;

[0024] The state-space equation of the system can be expressed as:

[0025]

[0026] In the formula: For system state variables; u(t) = [f s1 f s2 f s3 f s4 [q1 q2 q3 q4] represents the control input, which is the vertical control force calculated by the MPC controller (Model Predictive Controller) at the current moment to suppress suspension vibration; y(t) represents the control output; ω(t) = [q1 q2 q3 q4] represents the external disturbance; A and C are the system matrices; B u D is the input matrix; u For the output matrix; B w and D w Let be the perturbation matrix.

[0027] Furthermore, the optimal vertical control force is calculated based on the model predictive controller, specifically as follows:

[0028] The system output is defined as the vertical acceleration of the vehicle's center of gravity. Dynamic travel f at each suspension load point di Four-wheel tire dynamic load FDL i , can be represented as:

[0029]

[0030] Meanwhile, x represents the state variable of the prediction model, u represents the input variable of the prediction model, and y represents the output variable of the prediction model. Discretizing the continuous-time state equation, it can be expressed as:

[0031]

[0032] in:

[0033]

[0034] In the formula: A d and C d B du D du B dw and D dw These are the system matrix, input matrix, output matrix, and disturbance matrix in the discretized state space, respectively; T s τ is the sampling time; τ is the integration time constant.

[0035] Vertical acceleration of the center of mass, suspension dynamic travel, and tire dynamic load are selected as the control objectives of the MPC controller to optimize the active suspension performance from the perspective of attenuating vertical vibration. Based on the discrete-time state equations, the objective function is constructed as follows:

[0036]

[0037] In the formula: J is the objective function; y is the output of the prediction model; u is the input of the prediction model; Q i and R i y is a symmetric positive definite weighted matrix; ref Let y be the target reference trajectory, representing the reference values ​​for the vehicle's vertical acceleration of the center of gravity, suspension dynamic travel, and tire dynamic load. The closer these reference values ​​are to 0, the better the suspension performance. Therefore, the reference vector y is... ref =[0 0 0 0 0 0 0 00] T .

[0038] The constraint on the suspension dynamic travel can be expressed as:

[0039] f dpress ≤f di ≤f dstretch

[0040] In the formula: f dpress f represents the extreme value of the suspension compression stroke. dstretch This represents the extreme value of the suspension extension stroke.

[0041] At the same time, the control force f is considered in conjunction with the characteristics of the electromagnetic linear motor. si The constraint can be expressed as:

[0042] |f si |≤fsimax

[0043] In the formula: f simax The maximum vertical control force that an electromagnetic linear motor can provide

[0044] Therefore, the vertical model predictive control problem of the system can be expressed as:

[0045] minJ

[0046] stx(k+1)=A d x(k)+B du u(k)

[0047] |y(k+i)|≤y max

[0048] |u(k+i)|≤u max

[0049] In the formula: J is the objective function; x is the state variable of the prediction model; y is the output variable of the prediction model; u is the input variable of the prediction model; A d B is the discretized system matrix; du This is the discretized input matrix.

[0050] Furthermore, the vehicle body attitude control force is calculated based on the fuzzy controller, specifically as follows:

[0051] The center of gravity roll angle and pitch angle were selected as feedback parameters, and a two-input four-output fuzzy controller was determined. The controller's inputs include the pitch angle and roll angle, and its outputs are the attitude compensation forces Δf of the four suspensions. ij Through simulation analysis of the passive suspension, it was determined that the basic universe of discourse for the controller input and output are both [-6, 6].

[0052] The input and output states of the fuzzy controller are described using three terms: large, medium, and small. In addition to the zero state and positive and negative, there are seven fuzzy variables: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large. These are abbreviated in English as [NB, NM, NS, O, PS, PM, PB].

[0053] Considering the maximum values ​​of pitch and roll angles are 0.05 rad and 0.1 rad respectively, the pitch angle quantization factor K1 is set to 120, and the roll angle quantization factor K2 is set to 60. Meanwhile, to avoid excessive vehicle attitude control force affecting the overall vehicle active control effect, the maximum value of the vehicle attitude control force is controlled at around 1000 N, and the attitude control force quantization factor K3 is set to 200, thus determining the input and output membership functions.

[0054] In the Matlab fuzzy logic controller, fuzzy rules are represented using conditional statements. For example, if e = NM and ec = NB, then U1 = NS, U2 = PB, U3 = NB, and U4 = NS. This can be expressed as if (e is NM) and (ec is NB) then (U1 is NS)(U2 is PB)(U3 is NB)(U4 is NS). This determines the fuzzy rules, which are then represented using a surface observer to calculate the vehicle body attitude control force.

[0055] Furthermore, the target current required for the electromagnetic linear actuator is calculated, specifically as follows:

[0056] The optimal vertical control force f si With vehicle body attitude control force Δf ij The electromagnetic force F required to synthesize the active suspension is obtained. ti , can be represented as:

[0057] F ti =f si +Δf ij

[0058] Neglecting the end effects of the electromagnetic linear actuator and disregarding magnetic circuit saturation, the voltage balance equation in the dq-axis coordinate system can be expressed by the following equation:

[0059]

[0060] In the formula: u is the voltage value; Ψ is the magnetic flux linkage; ω r R is the angular velocity; R is the primary winding resistance; i is the current value;

[0061] The flux linkage equation can be expressed as:

[0062]

[0063] In the formula: L is the inductance; Ψ pm This refers to the flux linkage amplitude.

[0064] The equation for electromagnetic force can be expressed as:

[0065]

[0066] Where: N P τ is the polar logarithm; τ is the polar moment;

[0067] The kinematic equations are:

[0068]

[0069] In the formula: m is the mass of the mover; v is the velocity of the mover relative to the stator; F L B is the load force; B is the damping coefficient.

[0070] angular velocity ω r The following transformation relationship exists between the velocity v and the motion:

[0071]

[0072] The electromagnetic linear motor uses field-oriented control, at which point i d =0, i q =i, electromagnetic force can be expressed as:

[0073]

[0074] From the above equation, the electromagnetic force is directly proportional to the input current. Let K i =3πN P ψ pm / 2τ is the inference constant, and the target current i can be expressed as:

[0075]

[0076] A control system for an active control method for vehicle posture compensation includes an acceleration sensor, a displacement sensor, a three-axis gyroscope, and a controller. The controller includes a vertical control module, a vehicle posture control module, a vehicle posture compensation module, and an electromagnetic linear actuator module.

[0077] The vertical control module is used to calculate the optimal vertical control force based on the model prediction algorithm;

[0078] The vehicle attitude control module is used to calculate the vehicle attitude control force according to a fuzzy algorithm;

[0079] The vehicle attitude compensation module is used to synthesize the optimal vertical control force and vehicle attitude control force to obtain the electromagnetic force required by the system.

[0080] The electromagnetic linear actuator module obtains the target current according to the electromagnetic actuation force required by the system, and outputs the electromagnetic actuation force to realize active control of vehicle body attitude compensation.

[0081] The beneficial effects of this invention are as follows:

[0082] 1. The vehicle posture compensation active control method of the present invention calculates the optimal vertical control force required for each suspension through a model prediction algorithm and uses a fuzzy controller to calculate the vehicle posture control force required for each suspension. It proposes a vehicle posture compensation active control method and system, which is a control method and system to ensure vehicle ride comfort and driving stability.

[0083] 2. The active control method for vehicle posture compensation described in this invention inputs a target current into the driver, causing the electromagnetic linear actuator to output active force. The suspension system can attenuate the vertical vibration of the vehicle when the road excitation is too large, improve the vehicle ride comfort, suppress the deterioration of the vehicle posture during rapid acceleration, deceleration or high-speed steering, and avoid the vehicle posture from becoming unstable, thereby meeting the vehicle stability requirements.

[0084] 3. In comparison with the active suspension control strategy of the vehicle posture compensation active control method described in this invention, which uses a semi-active suspension, the active suspension control strategy proposed in this invention uses a linear motor as an actuator, and the force it generates is not limited by the relative speed at both ends of the suspension. Attached Figure Description

[0085] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0086] Figure 1 This is the seven-degree-of-freedom suspension dynamics model of the whole vehicle in this invention;

[0087] Figure 2 This is the membership curve of the input quantity in the fuzzy controller of the present invention;

[0088] Figure 3 This is the membership curve of the output quantity in the fuzzy controller of the present invention;

[0089] Figure 4 The left front suspension attitude compensation force (Δf) in this invention LF ) Change surface plot;

[0090] Figure 5 The left rear suspension attitude compensation force (Δf) in this invention LR ) Change surface plot;

[0091] Figure 6 The right front suspension attitude compensation force (Δf) in this invention RF ) Change surface plot;

[0092] Figure 7 The right rear suspension attitude compensation force (Δf) in this invention RR ) Change surface plot;

[0093] Figure 8 This is a diagram of the active control framework for vehicle body posture compensation according to the present invention. Detailed Implementation

[0094] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0095] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0096] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0097] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0098] The vehicle body posture compensation active control method of the present invention uses an electromagnetic linear actuator to output active force to reasonably control each suspension, attenuate the vertical vibration of the vehicle, effectively suppress the deterioration of the vehicle body posture, and improve the vehicle's ride comfort and driving stability. The method includes the following steps:

[0099] S01. Calculate the optimal vertical control force:

[0100] according to Figure 1 The seven-DOF suspension vibration model of the vehicle shown, combined with Newton's second law and vehicle dynamics characteristics, constructs the seven-DOF dynamic equations of the vehicle as follows:

[0101] The equations of motion for vertical, roll, and pitch at the vehicle's center of gravity can be expressed by the following formula:

[0102]

[0103] Where: m b For the sprung mass of the vehicle; z c B represents the vertical displacement at the vehicle's center of gravity. f B r These are half the track width of the front axle and half the track width of the rear axle, respectively; f l r θ represents the distances from the front and rear wheels to the vehicle's lateral centerline, respectively; θ is the vehicle's pitch angle. This refers to the vehicle body roll angle; I θ These are the moments of inertia of the vehicle body about the x-axis and y-axis, respectively; f i (i = 1, 2, 3, 4, the same below) represents the suspension force;

[0104] The equation for the vertical displacement of the wheel is:

[0105]

[0106] Where: m wi For tire mass; z wi k represents the vertical displacement of each tire. ti For tire stiffness; q i The road surface excitation experienced by each suspension;

[0107] The suspension force can be expressed as:

[0108]

[0109] In the formula: c i Z is the damping coefficient of the shock absorber; si k represents the vertical displacement at each suspension load point. si For suspension spring stiffness; F ti Provides the main power to the suspension for the electromagnetic actuator;

[0110] Based on the seven-degree-of-freedom dynamic equations of the vehicle, the state-space equations of the system can be determined by the following formula:

[0111]

[0112] In the formula: y(t) is the system state variable; y(t) is the control output variable; u(t) = [f s1 f s2 f s3 f s4[q1 q2 q3 q4] represents the control input, which is the vertical control force calculated by the MPC controller to suppress suspension vibration at the current moment; ω(t) = [q1 q2 q3 q4] represents the external disturbance; A and C are the system matrices; B u D is the input matrix; u For the output matrix; B w and D w Let be the perturbation matrix.

[0113] Furthermore, the optimal vertical control force is calculated based on the model predictive controller, specifically as follows:

[0114] The system output is defined as the vertical acceleration of the vehicle's center of gravity. Dynamic travel f at each suspension load point di Four-wheel tire dynamic load FDL i , can be represented as:

[0115]

[0116] Meanwhile, x represents the state variable of the prediction model, u represents the input variable of the prediction model, and y represents the output variable of the prediction model. Discretizing the continuous-time state equation, it can be expressed as:

[0117]

[0118] in:

[0119]

[0120] In the formula: A d and C d B du D du B dw and D dw These are the system matrix, input matrix, output matrix, and disturbance matrix in the discretized state space, respectively; T s τ is the sampling time; τ is the integration time constant.

[0121] Vertical acceleration of the center of gravity, suspension dynamic travel, and tire dynamic load are selected as the control objectives of the MPC controller to optimize the active suspension performance from the perspective of attenuating vertical vibration. Based on the discrete-time state equations, the objective function is constructed as follows:

[0122]

[0123] In the formula: J is the objective function; y is the output of the prediction model; u is the input of the prediction model; Q i and R i y is a symmetric positive definite weighted matrix; refLet y be the target reference trajectory, representing the reference values ​​for the vehicle's vertical acceleration of the center of gravity, suspension dynamic travel, and tire dynamic load. The closer these reference values ​​are to 0, the better the suspension performance. Therefore, the reference vector y is... ref =[0 0 0 0 0 0 0 00] T .

[0124] The constraint on the suspension dynamic travel can be expressed as:

[0125] f dpress ≤f di ≤f dstretch

[0126] In the formula: f dpress f represents the extreme value of the suspension compression stroke. dstretch This represents the extreme value of the suspension extension stroke.

[0127] At the same time, the control force f is considered in conjunction with the characteristics of the electromagnetic linear motor. si The constraint can be expressed as:

[0128] |f si |≤f simax

[0129] In the formula: f simax The maximum vertical control force that an electromagnetic linear motor can provide.

[0130] The optimization problem of the objective function under the constraint equations is transformed into a typical quadratic optimal programming problem. Therefore, the vertical model predictive control problem of the system can be expressed as:

[0131] minJ

[0132] stx(k+1)=A d x(k)+B du u(k)

[0133] |y(k+i)|≤y max

[0134] |u(k+i)|≤u max

[0135] In the formula: J is the objective function; x is the state variable of the prediction model; y is the output variable of the prediction model; u is the input variable of the prediction model; A d B is the discretized system matrix; du This is the discretized input matrix.

[0136] S02, Calculate vehicle attitude control force:

[0137] During vehicle operation, the pitch angle θ and roll angle of the center of gravity are obtained from the three-axis gyroscope. This is then used as a feedback parameter to determine a two-input, four-output fuzzy controller. The controller's inputs include pitch and roll angles, and its outputs are the attitude compensation forces Δf of the four suspensions. ij Through simulation analysis of the passive suspension, it was determined that the basic universe of discourse for the controller input and output are both [-6, 6].

[0138] The input and output states of the fuzzy controller are described using three terms: large, medium, and small. In addition to the zero state and positive and negative, there are seven fuzzy variables: negative large, negative medium, negative small, zero, positive small, positive medium, and positive large. These are abbreviated in English as [NB, NM, NS, O, PS, PM, PB].

[0139] Considering the maximum values ​​of pitch and roll angles are 0.05 rad and 0.1 rad respectively, the pitch angle quantization factor K1 is set to 120, and the roll angle quantization factor K2 is set to 60. Meanwhile, to avoid excessive vehicle attitude control force affecting the overall vehicle active control effect, the maximum value of the vehicle attitude control force is controlled to around 1000 N, and the attitude control force quantization factor K3 is set to 200. Furthermore, the following parameters are determined: Figure 3 The input membership function shown and such Figure 4 The output membership function is shown.

[0140] In Matlab fuzzy logic controllers, fuzzy rules are represented using conditional statements. For example, if e = NM and ec = NB, then U1 = NS, U2 = PB, U3 = NB, and U4 = NS. This can be expressed as if (e is NM) and (ec is NB) then (U1 is NS)(U2 is PB)(U3 is NB)(U4 is NS). This determines the fuzzy rules, which are then represented using a surface observer, such as... Figures 5-8 As shown, the vehicle body attitude control force is calculated.

[0141] S03. Calculate the target current required for the electromagnetic linear actuator:

[0142] according to Figure 8 The diagram shown illustrates the active control framework for vehicle body attitude compensation, which uses the optimal vertical control force f. si With vehicle body attitude control force Δf ij The electromagnetic force F required to synthesize the active suspension is obtained. ti , can be represented as:

[0143] F ti =f si +Δf ij

[0144] Neglecting the end effects of the electromagnetic linear actuator and disregarding magnetic circuit saturation, the voltage balance equation in the dq-axis coordinate system can be expressed by the following equation:

[0145]

[0146] In the formula: u is the voltage value; Ψ is the magnetic flux linkage; ω r R is the angular velocity; R is the primary winding resistance; i is the current value;

[0147] The flux linkage equation can be expressed as:

[0148]

[0149] In the formula: L is the inductance; Ψ pm This refers to the flux linkage amplitude.

[0150] The equation for electromagnetic force can be expressed as:

[0151]

[0152] Where: N P τ is the polar logarithm; τ is the polar moment;

[0153] The kinematic equations are:

[0154]

[0155] In the formula: m is the mass of the mover; v is the velocity of the mover relative to the stator; F L B is the load force; B is the damping coefficient.

[0156] angular velocity ω r The following transformation relationship exists between the velocity v and the motion:

[0157]

[0158] The electromagnetic linear motor uses field-oriented control, at which point i d =0, i q =i, electromagnetic force can be expressed as:

[0159]

[0160] From the above equation, the electromagnetic force is directly proportional to the input current. Let K i =3πN P ψ pm / 2τ is the inference constant, and the target current i can be expressed as:

[0161]

[0162] A control system for an active control method for vehicle posture compensation includes an acceleration sensor, a displacement sensor, a three-axis gyroscope, and a controller. The controller includes a vertical control module, a vehicle posture control module, a vehicle posture compensation module, and an electromagnetic linear actuator module.

[0163] The vertical control module is used to calculate the optimal vertical control force based on the model prediction algorithm;

[0164] The vehicle attitude control module is used to calculate the vehicle attitude control force according to a fuzzy algorithm;

[0165] The vehicle attitude compensation module is used to synthesize the optimal vertical control force and vehicle attitude control force to obtain the electromagnetic force required by the system.

[0166] The electromagnetic linear actuator module obtains the target current according to the electromagnetic actuation force required by the system, and outputs the electromagnetic actuation force to realize active control of vehicle body attitude compensation.

[0167] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0168] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for active control of vehicle body posture compensation, characterized in that, Includes the following steps: S01. Calculate the optimal vertical control force: During vehicle operation, the vertical acceleration of the vehicle's center of gravity and the vertical displacement at the suspension load point are obtained from acceleration and displacement sensors. The state-space equation of the system is constructed based on the motion equations of the seven-degree-of-freedom suspension dynamics model of the whole vehicle, and the optimal vertical control force f is solved using a model predictive controller. si ; S02, Calculate vehicle attitude control force: During vehicle operation, the pitch angle θ and roll angle φ of the center of gravity are obtained from the three-axis gyroscope and input into the fuzzy controller. The vehicle attitude control force f is then calculated using a fuzzy algorithm. fi This generates anti-pitch and anti-roll moments to control the vehicle's attitude; S03. Calculate the target current required for the electromagnetic linear actuator: The optimal vertical control force f si and vehicle body attitude control force f fi The summation yields the electromagnetic force F required for suspension control. ti Divide it by the thrust constant K i The target current i is obtained and input into the driver to make the electromagnetic linear actuator generate the electromagnetic force required for active suspension; The state-space equations of the system are constructed based on the motion equations of the seven-degree-of-freedom dynamic model of the vehicle, specifically: The equations of motion for vertical, roll, and pitch at the vehicle's center of gravity are: ； Where: m b z is the sprung mass of the vehicle. c B represents the vertical displacement at the vehicle's center of gravity. f B r These are half the track width of the front axle and half the track width of the rear axle, respectively; f l r θ represents the distance from the front wheel and rear wheel to the vehicle's lateral centerline, respectively; φ represents the vehicle's pitch angle; φ represents the vehicle's roll angle; I φ I θ These are the moments of inertia of the vehicle body about the x-axis and y-axis, respectively; f i For suspension forces, where the subscripts i = 1, 2, 3, 4, and so on; The equation for the vertical displacement of the wheel is: ； Where: m wi For tire mass; z wi k represents the vertical displacement of each tire. ti For tire stiffness; q i The road surface excitation experienced by each suspension; The suspension force can be expressed as: ； In the formula: c i Z is the damping coefficient of the shock absorber; si k represents the vertical displacement at each suspension load point. si For suspension spring stiffness; F ti Provides the main power to the suspension for the electromagnetic actuator; The state-space equation of the system can be expressed as: ； In the formula: For system state variables; To control the input, the vertical control force calculated by the model predictive controller at the current moment to suppress suspension vibration; To control the output; External disturbance; A and C are system matrices; B u D is the input matrix; u For the output matrix; B w and D w Let be the perturbation matrix.

2. The active control method for vehicle body attitude compensation according to claim 1, characterized in that, The optimal vertical control force is calculated based on the model predictive controller, specifically as follows: The system output is defined as the vertical acceleration of the vehicle's center of gravity. c ; Dynamic travel f at each suspension load-bearing point di Four-wheel tire dynamic load FDL i , can be represented as: ； Meanwhile, x is the state variable of the prediction model, u is the input of the prediction model, and y is the output of the prediction model. Discretizing the continuous-time state equation, it can be expressed as: ； in: ； In the formula: A d and C d B du D du B dw and D dw These are the system matrix, input matrix, output matrix, and disturbance matrix in the discretized state space, respectively; T s τ is the sampling time; τ is the integration time constant. Vertical acceleration of the center of mass, suspension dynamic travel, and tire dynamic load are selected as the control objectives of the model predictive controller. The active suspension performance is optimized from the perspective of attenuating vertical vibration. Based on the discrete-time state equations, the objective function is constructed as follows: ； In the formula: J is the objective function; y is the output of the prediction model; u is the input of the prediction model; Q i and R i y is a symmetric positive definite weighted matrix; ref Let y be the target reference trajectory, representing the reference values ​​for the vehicle's vertical acceleration of the center of gravity, suspension dynamic travel, and tire dynamic load. The closer these reference values ​​are to 0, the better the suspension performance. Therefore, the reference vector y is... ref =[0 0 0 0 0 0 0 0 0] T ; The constraint on the suspension dynamic travel can be expressed as: ； In the formula: f dpress f represents the extreme value of the suspension compression stroke. dstretch This represents the extreme value of the suspension extension stroke. Simultaneously, the optimal vertical control force f is considered in conjunction with the characteristics of the electromagnetic linear motor. si The constraint can be expressed as: ； In the formula: f simax The maximum vertical control force that an electromagnetic linear motor can provide Therefore, the vertical model predictive control problem of the system can be expressed as: ， s.t. , ， ； In the formula: J is the objective function; x is the state variable of the prediction model; y is the output variable of the prediction model; u is the input variable of the prediction model; A d B is the discretized system matrix; du This is the discretized input matrix.

3. The active control method for vehicle body attitude compensation according to claim 1, characterized in that, The vehicle body attitude control force is calculated based on the fuzzy controller, specifically as follows: The center of gravity roll angle and pitch angle were selected as feedback parameters, and a two-input four-output fuzzy controller was determined. The inputs of the fuzzy controller include the pitch angle and roll angle, and the outputs are the attitude compensation forces Δf of the four suspensions. ij Through simulation analysis of the passive suspension, it was determined that the basic universe of discourse for the controller input and output are both [-6, 6]. The input and output states of the fuzzy controller are described using three terms: large, medium, and small. In addition to the zero state and positive and negative, they are divided into seven fuzzy variables: negative large NB, negative medium NM, negative small NS, zero O, positive small PS, positive medium PM, and positive large PB. Considering that the maximum values ​​of pitch angle and roll angle are 0.05 rad and 0.1 rad respectively, the pitch angle quantization factor K1 is set to 120 and the roll angle quantization factor K2 is set to 60. At the same time, in order to avoid the excessive body attitude control force affecting the active control effect of the whole vehicle, the maximum value of the body attitude control force is controlled at 1000N and the attitude control force quantization factor K3 is set to 200, thereby determining the input and output membership functions. In the Matlab fuzzy controller, fuzzy rules are represented using conditional statements. If the inputs are e=NM and ec=NB, the outputs are U1=NS, U2=PB, U3=NB, and U4=NS. This determines the fuzzy rules, which are then represented using a surface observer to calculate the vehicle body attitude control force.

4. The active control method for vehicle body attitude compensation according to claim 1, characterized in that, The target current required for the electromagnetic linear actuator is calculated as follows: The optimal vertical control force f si With vehicle body attitude control force Δf ij The electromagnetic force F required to synthesize the active suspension is obtained. ti , can be represented as: ； Neglecting the end effects of the electromagnetic linear actuator and disregarding magnetic circuit saturation, the voltage balance equation in the dq-axis coordinate system can be expressed by the following equation: ； In the formula: u d、 u q These are the d-axis and q-axis voltage values; Ψ d、 Ψ q ω represents the magnetic flux linkages along the d and q axes; r ω is the angular velocity; R is the primary winding resistance; i d、 i q These are the d-axis and q-axis current values; The flux linkage equation can be expressed as: ； In the formula: L is the inductance; Ψ pm This refers to the flux linkage amplitude. The equation for electromagnetic force can be expressed as: ； Where: N P τ is the polar logarithm; τ is the polar moment; The kinematic equations are: ； In the formula: m is the mass of the mover; v is the velocity of the mover relative to the stator; F L B is the load force; B is the damping coefficient. angular velocity ω r The following transformation relationship exists between the velocity v and the motion: ； The electromagnetic linear motor uses field-oriented control, at which point i d = 0, i q = i, electromagnetic force can be expressed as: ； From the above equation, the electromagnetic force is directly proportional to the input current. Let... Let i be the inference constant, and the target current i can be expressed as: .

5. A control system for a vehicle body attitude compensation active control method, comprising the vehicle body attitude compensation active control method as described in any one of claims 1 to 4, characterized in that, It includes an acceleration sensor, a displacement sensor, a three-axis gyroscope, and a controller connected to them. The controller includes a vertical control module, a vehicle attitude control module, a vehicle attitude compensation module, and an electromagnetic linear actuator module. The vertical control module is used to calculate the optimal vertical control force based on the model prediction algorithm; The vehicle attitude control module is used to calculate the vehicle attitude control force according to a fuzzy algorithm; The vehicle attitude compensation module is used to synthesize the optimal vertical control force and vehicle attitude control force to obtain the electromagnetic force required by the system. The electromagnetic linear actuator module obtains the target current according to the electromagnetic actuation force required by the system, and outputs the electromagnetic actuation force to realize active control of vehicle body attitude compensation.

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