Vehicle active suspension control method and system considering road slope influence

Abstract

The invention provides a vehicle active suspension control method and system considering the influence of a road surface slope, and relates to the technical field of vehicle control, and the method comprises the steps: constructing an active suspension dynamic model and an ideal reference model of a three-axle vehicle considering the influence of the road surface slope; obtaining a vehicle vertical displacement error, a vehicle pitch angle error and a vehicle roll angle error based on the model; acquiring vehicle vertical motion lumped interference, vehicle pitching motion lumped interference and vehicle roll motion lumped interference based on an extended state observer; the ideal control force of the vehicle is further obtained; and decoupling based on the ideal control force of the vehicle to obtain the active action force of each suspension. According to the method, the influence of the slope of the road surface on the dynamic model of the three-axis vehicle active suspension is considered, the actual dynamic state of the vehicle can be reflected more accurately, and energy consumption is low while the excellent vibration isolation effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and in particular to a vehicle active suspension control method and system taking into account the influence of road slope. Background Art

[0002] Benefiting from the rapid development of industrial technology, the power and safety of automobiles have been greatly improved, and automobile manufacturers have begun to pay more attention to noise, vibration and roughness issues. As the most important vehicle chassis component, the suspension system can reasonably isolate or suppress the vibration of the vehicle under uneven roads, driving, braking and steering conditions, which directly determines the ride comfort and handling stability of the vehicle. Unlike passive suspension and semi-active suspension, the active suspension system is equipped with an actuator between the body and the axle, which can consume external energy to generate control force while changing the stiffness and damping coefficient, thereby suppressing the transmission of vibration, so it has great potential in improving the overall performance of the vehicle.

[0003] In recent years, scholars have established different active suspension dynamic models, usually including a quarter vehicle model, a half vehicle model or a whole vehicle model. In fact, vehicles usually travel on unstructured roads and sloped roads, which will inevitably lead to changes in the body posture, thereby affecting the vehicle's ride comfort and handling stability. However, in the modeling of existing active suspension control research, the factor of road slope is ignored; in addition, the actual suspension system model may be different from the expected model. Due to the changes in the number of passengers and vehicle load, there are inevitably some uncertain parameters in the active suspension system, such as sprung mass and moment of inertia. Due to the influence of wear on vehicle suspension components, the suspension parameters are also uncertain. If the unknown parameters and dynamics are not considered in the controller design, the control performance will be affected; in addition, with the rapid development of the economy, the world's energy is becoming increasingly scarce, and the increasing number of cars has exacerbated the energy crisis, which has a negative impact on the living environment. The existing active suspension control method only targets the suspension damping performance and ignores the energy consumption of the active suspension. Summary of the invention

[0004] The purpose of the present invention is to provide a vehicle active suspension control method and system that takes into account the influence of road slope, taking into account the influence of road slope on the dynamic model of the active suspension of a three-axle vehicle, and can more accurately reflect the actual dynamics of the vehicle; an energy-saving active suspension backstepping tracking controller is designed, which has excellent vibration isolation effect and low energy consumption.

[0005] A vehicle active suspension control method considering the influence of road slope, comprising:

[0006] The active suspension dynamics model and ideal reference model of a three-axle vehicle considering the influence of road slope are constructed; the three axles of a three-axle vehicle are the front axle, the middle axle and the rear axle;

[0007] The active suspension dynamics model is:

[0008]

[0009] The ideal reference model is:

[0010]

[0011] Where: m b is the mass of the three-axle vehicle, z b is the actual vertical displacement of the three-axle vehicle, is the actual vertical acceleration of the three-axle vehicle, P si is the nonlinear spring force of the ith suspension, N is the total number of suspensions, P di is the nonlinear damping force of the ith suspension, P ti is the wheel elastic force at the ith suspension, P tdi is the wheel damping force at the i-th suspension, d1 is the vertical disturbance, u i is the actual force input to the i-th suspension, J x is the moment of inertia of the vehicle body in the roll direction, J y is the moment of inertia of the vehicle body in the pitch direction, is the actual pitch angle of the vehicle, l Bi is the distance between the wheel at the ith suspension and the longitudinal centerline of the vehicle body, θ b is the actual roll angle of the vehicle, h b is the height of the vehicle's center of mass, is the vehicle body pitch angular acceleration, is the body roll angular acceleration, d2 is the pitch disturbance, d3 is the roll disturbance, l ei is the distance between the wheel at the ith suspension and the transverse centerline of the vehicle body, m wi is the unsprung mass at the ith suspension, z wi is the displacement of the unsprung mass at the ith suspension, z bd is the ideal reference vertical displacement, is the ideal reference vertical acceleration, is the ideal reference pitch angle, is the ideal reference pitch angle acceleration, θ bd is the ideal reference roll angle, is the ideal reference roll angle acceleration, c skyi is the ideal ceiling damping coefficient at the ith suspension, is the vertical displacement of the connection between the ith suspension and the vehicle body, c groundi is the ideal floor shed damping coefficient at the ith suspension, is the vertical motion speed of the wheel at the i-th suspension;

[0012] Based on the suspension dynamics model, the actual vertical displacement of the vehicle, the actual pitch angle of the vehicle and the actual roll angle of the vehicle are obtained; based on the ideal reference model, the ideal vertical displacement of the vehicle, the ideal pitch angle of the vehicle and the ideal roll angle of the vehicle are obtained;

[0013] Subtracting the ideal vertical displacement of the vehicle from the actual vertical displacement of the vehicle to obtain a vehicle vertical displacement error, subtracting the ideal pitch angle of the vehicle from the actual pitch angle of the vehicle to obtain a vehicle pitch angle error, and subtracting the ideal roll angle of the vehicle from the actual roll angle of the vehicle to obtain a vehicle roll angle error;

[0014] Constructing a vehicle vertical motion extended state observer, a vehicle pitch motion extended state observer and a vehicle roll motion extended state observer;

[0015] Based on the vehicle vertical displacement error, in combination with the vehicle vertical motion extended state observer, the vehicle vertical motion lumped disturbance is obtained; based on the vehicle pitch angle error, in combination with the vehicle pitch motion extended state observer, the vehicle pitch motion lumped disturbance is obtained; based on the vehicle roll angle error, in combination with the vehicle roll motion extended state observer, the vehicle roll motion lumped disturbance is obtained;

[0016] Based on the lumped disturbance of the vertical motion of the vehicle and the vertical displacement error of the vehicle, an ideal control force in the vertical direction of the vehicle is obtained; based on the lumped disturbance of the pitch motion of the vehicle and the pitch angle error of the vehicle, an ideal control force in the pitch direction of the vehicle is obtained; based on the lumped disturbance of the roll motion of the vehicle and the roll angle error of the vehicle, an ideal control force in the roll direction of the vehicle is obtained;

[0017] The ideal control force in the vertical direction of the vehicle, the ideal control force in the pitch direction of the vehicle and the ideal control force in the roll direction of the vehicle are decoupled to obtain the active dynamic force of each suspension of the vehicle.

[0018] Optionally, the expression of the vehicle vertical motion extended state observer is:

[0019]

[0020] The expression of the vehicle pitch motion extended state observer is:

[0021]

[0022] The expression of the vehicle roll motion extended state observer is:

[0023]

[0024] Where: e zis the vehicle vertical displacement error, is the vehicle pitch angle error, e θ is the vehicle roll angle error, b z1 =3ω z , ω z is the first positive vertical parameter, is the first positive parameter of pitch, b θ1 =3ω θ , ω θ is the first positive roll parameter, γ z is the second positive vertical parameter, is the second positive parameter of pitch, γ θ is the second positive parameter of roll, m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x The nominal value of is the first positive parameter, σ xy is the second positive parameter, 0<σ xy <1, δ is the design parameter, δ>0, y=1,2,3,U z (t) is the output force of the vertical motion controller, is the output force of the pitch motion controller, U θ (t) is the output force of the roll motion controller, and sign is the sign function.

[0025] Optionally, the ideal control force expression of the vehicle in the vertical direction is:

[0026]

[0027] The ideal control force expression of the vehicle pitch direction is:

[0028]

[0029] The ideal control force expression of the vehicle roll direction is:

[0030]

[0031] Where: U z It is the ideal control force in the vertical direction of the vehicle. k z is the vertical control gain, is the pitch control gain, k θ is the roll control gain, k z >0,

[0032] k θ >0,m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x Nominal value.

[0033] Optionally, the decoupling process of the active motion forces of each suspension is:

[0034]

[0035] Where: u i ′ represents the ideal force of the i-th suspension, l f Indicates the distance from the front axle to the vehicle's center of mass, l m Indicates the distance from the center axis to the center of mass of the vehicle, l r represents the distance between the rear axle and the center of mass of the vehicle, B represents the wheelbase of the left and right wheels, and inv represents the inverse matrix.

[0036] Alternatively, the nonlinear spring force expression of the i-th suspension is:

[0037] P si =k si (z bi -z wi )+k Nli (z wi -z bi ) 3 ;

[0038] The nonlinear damping force expression of the i-th suspension is:

[0039]

[0040] The wheel elastic force expression at the i-th suspension is:

[0041] P ti =k ti (z wi -z ri );

[0042] The wheel damping force expression at the i-th suspension is:

[0043]

[0044] Where: z biis the vertical displacement of the connection between the ith suspension and the vehicle body, is the vertical velocity of the connection between the ith suspension and the vehicle body, k si is the linear spring coefficient of the ith suspension, k Nli is the nonlinear spring coefficient of the ith suspension, c si is the linear damping coefficient of the ith suspension, c Nli is the nonlinear damping coefficient of the ith suspension, k ti is the wheel spring coefficient at the ith suspension, c tdi is the wheel damping coefficient at the ith suspension, z ri is the road-induced vertical displacement of the wheel at the ith suspension, is the road-excited vertical velocity of the wheel at the ith suspension.

[0045] The present invention also provides a vehicle active suspension control system taking into account the influence of road slope, which comprises:

[0046] A model building module is used to build an active suspension dynamics model and an ideal reference model of a three-axle vehicle taking into account the influence of road slope; the three axles of a three-axle vehicle are the front axle, the middle axle and the rear axle;

[0047] The active suspension dynamics model is:

[0048]

[0049] The ideal reference model is:

[0050]

[0051] Where: m b is the mass of the three-axle vehicle, z b is the actual vertical displacement of the three-axle vehicle, is the actual vertical acceleration of the three-axle vehicle, P si is the nonlinear spring force of the ith suspension, N is the total number of suspensions, P di is the nonlinear damping force of the ith suspension, P ti is the wheel elastic force at the ith suspension, P tdi is the wheel damping force at the i-th suspension, d1 is the vertical disturbance, u i is the actual force input to the i-th suspension, J x is the moment of inertia of the vehicle body in the roll direction, J y is the moment of inertia of the vehicle body in the pitch direction, is the actual pitch angle of the vehicle, l Bi is the distance between the wheel at the ith suspension and the longitudinal centerline of the vehicle body, θ b is the actual roll angle of the vehicle, h bis the height of the vehicle's center of mass, is the vehicle body pitch angular acceleration, is the body roll angular acceleration, d2 is the pitch disturbance, d3 is the roll disturbance, l ei is the distance between the wheel at the ith suspension and the transverse centerline of the vehicle body, m wi is the unsprung mass at the ith suspension, z wi is the displacement of the unsprung mass at the ith suspension, z bd is the ideal reference vertical displacement, is the ideal reference vertical acceleration, is the ideal reference pitch angle, is the ideal reference pitch angle acceleration, θ bd is the ideal reference roll angle, is the ideal reference roll angle acceleration, c skyi is the ideal ceiling damping coefficient at the ith suspension, is the vertical displacement of the connection between the ith suspension and the vehicle body, c groundi is the ideal floor shed damping coefficient at the ith suspension, is the vertical motion speed of the wheel at the i-th suspension;

[0052] A parameter acquisition module, used to obtain the actual vertical displacement of the vehicle, the actual pitch angle of the vehicle and the actual roll angle of the vehicle based on the suspension dynamics model; and to obtain the ideal vertical displacement of the vehicle, the ideal pitch angle of the vehicle and the ideal roll angle of the vehicle based on the ideal reference model;

[0053] a difference module, configured to obtain a vehicle vertical displacement error by subtracting the ideal vehicle vertical displacement from the actual vehicle vertical displacement, obtain a vehicle pitch angle error by subtracting the ideal vehicle pitch angle from the actual vehicle pitch angle, and obtain a vehicle roll angle error by subtracting the ideal vehicle roll angle from the actual vehicle roll angle;

[0054] An observer module is used to construct an expanded state observer for the vertical motion of a vehicle, an expanded state observer for the pitch motion of a vehicle, and an expanded state observer for the roll motion of a vehicle;

[0055] A disturbance module, configured to obtain a vehicle vertical motion lumped disturbance based on the vehicle vertical displacement error in combination with a vehicle vertical motion extended state observer, obtain a vehicle pitch motion lumped disturbance based on the vehicle pitch angle error in combination with a vehicle pitch motion extended state observer, and obtain a vehicle roll motion lumped disturbance based on the vehicle roll angle error in combination with a vehicle roll motion extended state observer;

[0056] A control force module, used for obtaining an ideal control force in the vertical direction of the vehicle based on the lumped disturbance of the vertical motion of the vehicle and the vertical displacement error of the vehicle, obtaining an ideal control force in the pitch direction of the vehicle based on the lumped disturbance of the pitch motion of the vehicle and the pitch angle error of the vehicle, and obtaining an ideal control force in the roll direction of the vehicle based on the lumped disturbance of the roll motion of the vehicle and the roll angle error of the vehicle;

[0057] The actuation force module is used to decouple the ideal control force in the vertical direction of the vehicle, the ideal control force in the pitch direction of the vehicle and the ideal control force in the roll direction of the vehicle to obtain the active actuation force of each suspension of the vehicle.

[0058] Optionally, the expression of the vehicle vertical motion extended state observer is:

[0059]

[0060] The expression of the vehicle pitch motion extended state observer is:

[0061]

[0062] The expression of the vehicle roll motion extended state observer is:

[0063]

[0064] Where: e z is the vehicle vertical displacement error, is the vehicle pitch angle error, e θ is the vehicle roll angle error, b z1 =3ω z , ω z is the first positive vertical parameter, is the first positive parameter of pitch, b θ1 =3ω θ , ω θ is the first positive roll parameter, γ z is the second positive vertical parameter, is the second positive parameter of pitch, γ θ is the second positive parameter of roll, m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x The nominal value of is the first positive parameter, σ xy is the second positive parameter, 0<σxy <1, δ is the design parameter, δ>0, y=1,2,3,U z (t) is the output force of the vertical motion controller, is the output force of the pitch motion controller, U θ (t) is the output force of the roll motion controller, and sign is the sign function.

[0065] Optionally, the ideal control force expression of the vehicle in the vertical direction is:

[0066]

[0067] The ideal control force expression of the vehicle pitch direction is:

[0068]

[0069] The ideal control force expression of the vehicle roll direction is:

[0070]

[0071] Where: U z It is the ideal control force in the vertical direction of the vehicle. k z is the vertical control gain, is the pitch control gain, k θ is the roll control gain, k z >0, k θ >0,m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x Nominal value.

[0072] Optionally, the decoupling process of the active motion forces of each suspension is:

[0073]

[0074] Where: u i ′ represents the ideal force of the i-th suspension, l f Indicates the distance from the front axle to the center of mass of the vehicle, l m Indicates the distance from the center axis to the center of mass of the vehicle, l r represents the distance between the rear axle and the center of mass of the vehicle, B represents the wheelbase of the left and right wheels, and inv represents the inverse matrix.

[0075] Alternatively, the nonlinear spring force expression of the i-th suspension is:

[0076] P si =k si (z bi -z wi )+k Nli (z wi -z bi ) 3 ;

[0077] The nonlinear damping force expression of the i-th suspension is:

[0078]

[0079] The wheel elastic force expression at the i-th suspension is:

[0080] P ti =k ti (z wi -z ri );

[0081] The wheel damping force expression at the i-th suspension is:

[0082]

[0083] Where: z bi is the vertical displacement of the connection between the ith suspension and the vehicle body, is the vertical velocity of the connection between the ith suspension and the vehicle body, k si is the linear spring coefficient of the ith suspension, k Nli is the nonlinear spring coefficient of the ith suspension, c si is the linear damping coefficient of the ith suspension, c Nli is the nonlinear damping coefficient of the ith suspension, k ti is the wheel spring coefficient at the ith suspension, c tdi is the wheel damping coefficient at the ith suspension, z ri is the road-induced vertical displacement of the wheel at the ith suspension, is the road-excited vertical velocity of the wheel at the ith suspension.

[0084] The effects of the present invention are as follows:

[0085] The vehicle active suspension control method considering the influence of road slope of the present invention takes into account the influence of road slope on the dynamic characteristics of vehicle suspension and fully considers the coupling effects of the vertical, roll and pitch directions of the vehicle body. The established active suspension dynamics model of the three-axle vehicle can more accurately reflect the actual dynamics of the vehicle.

[0086] The vehicle active suspension control method of the present invention takes into account the influence of road slope. In the modeling process, the internal uncertainty parameters of the whole vehicle suspension system and the influence of external interference are considered, and a nonlinear extended state observer in three motion directions is designed to estimate the total interference, thereby weakening or eliminating the influence of the interference in feedback control, avoiding the problems of the precise modeling process of the system and the complex calculation of neural networks and fuzzy approximation methods, and improving the active suspension control effect.

[0087] The present invention provides a vehicle active suspension control method that takes the influence of road slope into consideration, designs an ideal reference model with ceiling damping and floor damping having excellent vibration isolation effect as a desired trajectory for tracking control, and solves the problem that most existing control methods are not suitable for sloped roads.

[0088] The present invention provides a vehicle active suspension control method that takes the influence of road slope into consideration, designs an energy-saving active suspension back-step tracking controller, has excellent vibration isolation effect and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 This is a flow chart of the vehicle active suspension control method considering the influence of road slope in the present invention;

[0090] Figure 2 A schematic diagram of an active suspension dynamics model of a three-axle vehicle considering the road slope of the present invention;

[0091] Figure 3 It is a schematic diagram of the structure of the ideal reference model of the present invention;

[0092] Figure 4 It is a schematic diagram of the excitation of a sloped single-sided convex hull road surface;

[0093] Figure 5 It is a schematic diagram of the vertical acceleration response of the vehicle body under the excitation of a sloped single-sided convex road surface;

[0094] Figure 6 It is a schematic diagram of the acceleration response of the vehicle body in the pitch direction under the excitation of the sloped single-sided convex road surface;

[0095] Figure 7 It is a schematic diagram of the acceleration response of the vehicle body in the roll direction under the excitation of a sloped single-sided convex road surface;

[0096] Figure 8 It is a schematic diagram of the control force (N) input of the six actuators under the excitation of the slope single-sided convex road surface;

[0097] Fig. 9 Schematic diagram of the instantaneous power (W) consumed by the six actuators under the excitation of the sloped single-sided convex road surface;

[0098] Fig.10Schematic diagram of total energy consumption (J) of six actuators under the excitation of a sloped single-sided convex road surface;

[0099] Fig.11 Schematic diagram of the six suspension dynamic travels (m) under the excitation of a sloped single-sided convex road surface. DETAILED DESCRIPTION

[0100] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0101] Figure 1 FIG. 1 is a flow chart of the vehicle active suspension control method considering the influence of road slope in the present invention. Figure 1 As shown, the present invention provides a vehicle active suspension control method considering the influence of road slope, which includes:

[0102] S1, construct the active suspension dynamics model and ideal reference model of a three-axle vehicle considering the influence of road slope. The three axles of a three-axle vehicle are the front axle, the middle axle and the rear axle.

[0103] like Figure 2 As shown in Figure 2, the active suspension dynamics model is:

[0104]

[0105] like Figure 3 As shown, the ideal reference model is:

[0106]

[0107] Where: m b is the mass of the three-axle vehicle, z b is the actual vertical displacement of the three-axle vehicle, is the actual vertical acceleration of the three-axle vehicle, P si is the nonlinear spring force of the ith suspension, N is the total number of suspensions, P di is the nonlinear damping force of the ith suspension, P ti is the wheel elastic force at the ith suspension, P tdi is the wheel damping force at the i-th suspension, d1 is the vertical disturbance, u i is the actual force input to the i-th suspension, J x is the moment of inertia of the vehicle body in the roll direction, J y is the moment of inertia of the vehicle body in the pitch direction, is the actual pitch angle of the vehicle, l Bi is the distance between the wheel at the ith suspension and the longitudinal centerline of the vehicle body, θ b is the actual roll angle of the vehicle, h b is the height of the vehicle's center of mass, is the vehicle body pitch angular acceleration, is the body roll angular acceleration, d2 is the pitch disturbance, d3 is the roll disturbance, l ei is the distance between the wheel at the ith suspension and the transverse centerline of the vehicle body, m wi is the unsprung mass at the ith suspension, z wi is the displacement of the unsprung mass at the ith suspension, z bd is the ideal reference vertical displacement, is the ideal reference vertical acceleration, is the ideal reference pitch angle, is the ideal reference pitch angle acceleration, θ bd is the ideal reference roll angle, is the ideal reference roll angle acceleration, c skyi is the ideal ceiling damping coefficient at the ith suspension, is the vertical displacement of the connection between the ith suspension and the vehicle body, c groundi is the ideal floor shed damping coefficient at the ith suspension, is the vertical velocity of the wheel at the i-th suspension.

[0108] m b , J x and J y The following constraints are met:

[0109]

[0110] The nonlinear spring force expression of the i-th suspension is:

[0111] P si =k si (z bi -z wi )+k Nli (z wi -z bi ) 3 .

[0112] The nonlinear damping force expression of the i-th suspension is:

[0113]

[0114] The wheel elastic force expression at the i-th suspension is:

[0115] P ti =k ti (z wi -z ri ).

[0116] The wheel damping force expression at the i-th suspension is:

[0117]

[0118] Where: z bi is the vertical displacement of the connection between the ith suspension and the vehicle body, is the vertical velocity of the connection between the ith suspension and the vehicle body, k si is the linear spring coefficient of the ith suspension, k Nli is the nonlinear spring coefficient of the ith suspension, c si is the linear damping coefficient of the ith suspension, c Nli is the nonlinear damping coefficient of the ith suspension, k ti is the wheel spring coefficient at the ith suspension, c tdi is the wheel damping coefficient at the ith suspension, z ri is the road-induced vertical displacement of the wheel at the ith suspension, is the road-excited vertical velocity of the wheel at the ith suspension.

[0119] S2, based on the suspension dynamics model, the actual vertical displacement of the vehicle, the actual pitch angle of the vehicle and the actual roll angle of the vehicle are obtained; based on the ideal reference model, the ideal vertical displacement of the vehicle, the ideal pitch angle of the vehicle and the ideal roll angle of the vehicle are obtained.

[0120] S3, subtracting the ideal vertical displacement of the vehicle from the actual vertical displacement of the vehicle to obtain a vehicle vertical displacement error, subtracting the ideal pitch angle of the vehicle from the actual pitch angle of the vehicle to obtain a vehicle pitch angle error, and subtracting the ideal roll angle of the vehicle from the actual roll angle of the vehicle to obtain a vehicle roll angle error.

[0121] Specifically, Then the error model can be expressed as:

[0122]

[0123] S4, constructing a vehicle vertical motion expanded state observer, a vehicle pitch motion expanded state observer and a vehicle roll motion expanded state observer.

[0124] Specifically, the expression of the vehicle vertical motion extended state observer is:

[0125]

[0126] The expression of the extended state observer of vehicle pitch motion is:

[0127]

[0128] The expression of the extended state observer of vehicle roll motion is:

[0129]

[0130] Where: e z is the vehicle vertical displacement error, is the vehicle pitch angle error, e θ is the vehicle roll angle error, b z1 =3ω z , ω z is the first positive vertical parameter, is the first positive parameter of pitch, b θ1 =3ω θ , ω θ is the first positive roll parameter, γ z is the second positive vertical parameter, is the second positive parameter of pitch, γ θ is the second positive parameter of roll, m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x The nominal value of is the first positive parameter, σ xy is the second positive parameter, 0<σ xy <1, δ is the design parameter, δ>0, y=1,2,3,U z (t) is the output force of the vertical motion controller, is the output force of the pitch motion controller, U θ (t) is the output force of the roll motion controller, and sign is the sign function.

[0131] S5, based on the vehicle vertical displacement error, combined with the vehicle vertical motion expanded state observer, the vehicle vertical motion lumped disturbance is obtained; based on the vehicle pitch angle error, combined with the vehicle pitch motion expanded state observer, the vehicle pitch motion lumped disturbance is obtained; based on the vehicle roll angle error, combined with the vehicle roll motion expanded state observer, the vehicle roll motion lumped disturbance is obtained.

[0132] S6, based on the total disturbance of the vehicle's vertical motion and the vehicle's vertical displacement error, the ideal control force in the vertical direction of the vehicle is obtained; based on the total disturbance of the vehicle's pitch motion and the vehicle's pitch angle error, the ideal control force in the pitch direction of the vehicle is obtained; based on the total disturbance of the vehicle's roll motion and the vehicle's roll angle error, the ideal control force in the roll direction of the vehicle is obtained.

[0133] Furthermore, the ideal control force expression of the vehicle in the vertical direction is:

[0134]

[0135] The ideal control force expression of the vehicle pitch direction is:

[0136]

[0137] The ideal control force expression of the vehicle roll direction is:

[0138]

[0139] Where: U z It is the ideal control force in the vertical direction of the vehicle. k z is the vertical control gain, is the pitch control gain, k θ is the roll control gain, k z >0,

[0140] k θ >0,m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x Nominal value.

[0141] S7, decoupling the ideal control force in the vertical direction of the vehicle, the ideal control force in the pitch direction of the vehicle, and the ideal control force in the roll direction of the vehicle to obtain the active dynamic force of each suspension of the vehicle.

[0142] The decoupling process of the active motion force of each suspension is:

[0143]

[0144] Where: u i ′ represents the ideal force of the i-th suspension, l f Indicates the distance from the front axle to the center of mass of the vehicle, l m Indicates the distance from the center axis to the center of mass of the vehicle, l r represents the distance between the rear axle and the center of mass of the vehicle, B represents the wheelbase of the left and right wheels, and inv represents the inverse matrix.

[0145] Preferably, the system Lyapunov function is defined as:

[0146]

[0147] Taking its derivative we get:

[0148]

[0149] Will Substituting into the above formula, we can get:

[0150]

[0151] When t→∞,

[0152]

[0153] According to the Lyapunov-like lemma, if

[0154] (1) V>0

[0155] (2)V≤-g(t) when g(t)≥0.

[0156] (3)

[0157] Then

[0158] In the controller of the present invention:

[0159]

[0160] System Status z , e θ ,ξ2,ξ4,ξ6 and is bounded, so g(t) is bounded, so it is proved that the tracking error is asymptotically stable and the tracking error approaches 0 over time:

[0161]

[0162] The stability of the tracking controller is proved theoretically.

[0163] Specifically, taking a three-axle vehicle as an example, the excitation given to each wheel on a sloped single-sided convex road surface is as follows: Figure 4 Compared with the method of the present invention, the existing passive suspension and the existing ESOT controller, the vertical acceleration is as follows Figure 5 As shown, the pitch acceleration is Figure 6 As shown, the roll direction acceleration is Figure 7 As shown, the controller input of the actuator of each wheel is as follows Figure 8 As shown, the instantaneous power consumed by each actuator is as follows Fig. 9 As shown in Figure 2, the total energy consumption of each actuator is as follows: Fig.10 As shown in Figure 2, the travel of each suspension is as follows: Fig.11As shown, it can be seen that even on a convex road with a slope, the vibration acceleration of the vehicle in the vertical movement, pitch movement and roll movement directions is significantly reduced by the present invention, and the required active control force is smaller and the control energy consumed is less.

[0164] The present invention also provides a vehicle active suspension control system taking into account the influence of road slope, which comprises:

[0165] The model building module is used to build the active suspension dynamics model and ideal reference model of a three-axle vehicle considering the influence of road slope. The three axles of a three-axle vehicle are the front axle, the middle axle and the rear axle.

[0166] The active suspension dynamics model is:

[0167]

[0168] The ideal reference model is:

[0169]

[0170] Where: m b is the mass of the three-axle vehicle, z b is the actual vertical displacement of the three-axle vehicle, is the actual vertical acceleration of the three-axle vehicle, P si is the nonlinear spring force of the ith suspension, N is the total number of suspensions, P di is the nonlinear damping force of the ith suspension, P ti is the wheel elastic force at the ith suspension, P tdi is the wheel damping force at the i-th suspension, d1 is the vertical disturbance, u i is the actual force input to the i-th suspension, J x is the moment of inertia of the vehicle body in the roll direction, J y is the moment of inertia of the vehicle body in the pitch direction, is the actual pitch angle of the vehicle, l Bi is the distance between the wheel at the ith suspension and the longitudinal centerline of the vehicle body, θ b is the actual roll angle of the vehicle, h b is the height of the vehicle's center of mass, is the vehicle body pitch angular acceleration, is the body roll angular acceleration, d2 is the pitch disturbance, d3 is the roll disturbance, l ei is the distance between the wheel at the ith suspension and the transverse centerline of the vehicle body, m wi is the unsprung mass at the ith suspension, z wi is the displacement of the unsprung mass at the ith suspension, z bd is the ideal reference vertical displacement, is the ideal reference vertical acceleration, is the ideal reference pitch angle, is the ideal reference pitch angle acceleration, θ bd is the ideal reference roll angle, is the ideal reference roll angle acceleration, c skyi is the ideal ceiling damping coefficient at the ith suspension, is the vertical displacement of the connection between the ith suspension and the vehicle body, c groundi is the ideal floor shed damping coefficient at the ith suspension, is the vertical velocity of the wheel at the i-th suspension.

[0171] The parameter acquisition module is used to obtain the actual vertical displacement, the actual pitch angle and the actual roll angle of the vehicle based on the suspension dynamics model; and to obtain the ideal vertical displacement, the ideal pitch angle and the ideal roll angle of the vehicle based on the ideal reference model.

[0172] The difference module is used to obtain the vehicle vertical displacement error by subtracting the ideal vehicle vertical displacement from the actual vehicle vertical displacement, obtain the vehicle pitch angle error by subtracting the ideal vehicle pitch angle from the actual vehicle pitch angle, and obtain the vehicle roll angle error by subtracting the ideal vehicle roll angle from the actual vehicle roll angle.

[0173] The observer module is used to construct a vehicle vertical motion expanded state observer, a vehicle pitch motion expanded state observer and a vehicle roll motion expanded state observer.

[0174] The disturbance module is used to obtain the lumped disturbance of the vehicle's vertical motion based on the vehicle's vertical displacement error in combination with the vehicle's vertical motion expanded state observer, to obtain the lumped disturbance of the vehicle's pitch motion based on the vehicle's pitch angle error in combination with the vehicle's pitch motion expanded state observer, and to obtain the lumped disturbance of the vehicle's roll motion based on the vehicle's roll angle error in combination with the vehicle's roll motion expanded state observer.

[0175] The control force module is used to obtain the ideal control force in the vertical direction of the vehicle based on the total disturbance of the vertical motion of the vehicle and the vertical displacement error of the vehicle, to obtain the ideal control force in the pitch direction of the vehicle based on the total disturbance of the pitch motion of the vehicle and the pitch angle error of the vehicle, and to obtain the ideal control force in the roll direction of the vehicle based on the total disturbance of the roll motion of the vehicle and the roll angle error of the vehicle.

[0176] The actuation force module is used to decouple the ideal control force in the vertical direction of the vehicle, the ideal control force in the pitch direction of the vehicle and the ideal control force in the roll direction of the vehicle to obtain the active actuation force of each suspension of the vehicle.

[0177] Optionally, the expression of the vehicle vertical motion extended state observer is:

[0178]

[0179] The expression of the extended state observer of vehicle pitch motion is:

[0180]

[0181] The expression of the extended state observer of vehicle roll motion is:

[0182]

[0183] Where: e z is the vehicle vertical displacement error, is the vehicle pitch angle error, e θ is the vehicle roll angle error, b z1 =3ω z , ω z is the first positive vertical parameter, is the first positive parameter of pitch, b θ1 =3ω θ , ω θ is the first positive roll parameter, γ z is the second positive vertical parameter, is the second positive parameter of pitch, γ θ is the second positive parameter of roll, m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x The nominal value of is the first positive parameter, σ xy is the second positive parameter, 0<σ xy <1, δ is the design parameter, δ>0, y=1,2,3,U z (t) is the output force of the vertical motion controller, is the output force of the pitch motion controller, U θ (t) is the output force of the roll motion controller, and sign is the sign function.

[0184] Optionally, the ideal control force expression of the vehicle in the vertical direction is:

[0185]

[0186] The ideal control force expression of the vehicle pitch direction is:

[0187]

[0188] The ideal control force expression of the vehicle roll direction is:

[0189]

[0190] Where: U z It is the ideal control force in the vertical direction of the vehicle. k z is the vertical control gain, is the pitch control gain, k θ is the roll control gain, k z >0,

[0191] k θ >0,m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x Nominal value.

[0192] Optionally, the decoupling process of the active motion forces of each suspension is:

[0193]

[0194] Where: u i ′ represents the ideal force of the i-th suspension, l f Indicates the distance from the front axle to the center of mass of the vehicle, l m Indicates the distance from the center axis to the center of mass of the vehicle, l r represents the distance between the rear axle and the center of mass of the vehicle, B represents the wheelbase of the left and right wheels, and inv represents the inverse matrix.

[0195] Alternatively, the nonlinear spring force expression of the i-th suspension is:

[0196] P si =k si (z bi -z wi )+k Nli (z wi -z bi ) 3 .

[0197] The nonlinear damping force expression of the i-th suspension is:

[0198]

[0199] The wheel elastic force expression at the i-th suspension is:

[0200] P ti =k ti (z wi -z ri ).

[0201] The wheel damping force expression at the i-th suspension is:

[0202]

[0203] Where: z bi is the vertical displacement of the connection between the ith suspension and the vehicle body, is the vertical velocity of the connection between the ith suspension and the vehicle body, k si is the linear spring coefficient of the ith suspension, k Nli is the nonlinear spring coefficient of the ith suspension, c si is the linear damping coefficient of the ith suspension, c Nli is the nonlinear damping coefficient of the ith suspension, k ti is the wheel spring coefficient at the ith suspension, c tdi is the wheel damping coefficient at the ith suspension, z ri is the road-induced vertical displacement of the wheel at the ith suspension, is the road-excited vertical velocity of the wheel at the ith suspension.

[0204] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A vehicle active suspension control method considering the influence of road slope, characterized in that: It includes: The active suspension dynamics model and ideal reference model of a three-axle vehicle considering the influence of road slope are constructed; the three axles of a three-axle vehicle are the front axle, the middle axle and the rear axle; The active suspension dynamics model is: The ideal reference model is: Where: m b is the mass of the three-axle vehicle, z b is the actual vertical displacement of the three-axle vehicle, is the actual vertical acceleration of the three-axle vehicle, P si is the nonlinear spring force of the ith suspension, N is the total number of suspensions, P di is the nonlinear damping force of the ith suspension, P ti is the wheel elastic force at the ith suspension, P tdi is the wheel damping force at the i-th suspension, d1 is the vertical disturbance, u i is the actual force input to the i-th suspension, J x is the moment of inertia of the vehicle body in the roll direction, J y is the moment of inertia of the vehicle body in the pitch direction, is the actual pitch angle of the vehicle, l Bi is the distance between the wheel at the ith suspension and the longitudinal centerline of the vehicle body, θ b is the actual roll angle of the vehicle, h b is the height of the vehicle's center of mass, is the vehicle body pitch angular acceleration, is the body roll angular acceleration, d2 is the pitch disturbance, d3 is the roll disturbance, l ei is the distance between the wheel at the ith suspension and the transverse centerline of the vehicle body, m wi is the unsprung mass at the ith suspension, z wi is the displacement of the unsprung mass at the ith suspension, z bd is the ideal reference vertical displacement, is the ideal reference vertical acceleration, is the ideal reference pitch angle, is the ideal reference pitch angle acceleration, θ bd is the ideal reference roll angle, is the ideal reference roll angle acceleration, c skyi is the ideal ceiling damping coefficient at the ith suspension, is the vertical displacement of the connection between the ith suspension and the vehicle body, c groundi is the ideal floor shed damping coefficient at the ith suspension, is the vertical motion speed of the wheel at the i-th suspension; Based on the suspension dynamics model, the actual vertical displacement of the vehicle, the actual pitch angle of the vehicle and the actual roll angle of the vehicle are obtained; based on the ideal reference model, the ideal vertical displacement of the vehicle, the ideal pitch angle of the vehicle and the ideal roll angle of the vehicle are obtained; Subtracting the ideal vertical displacement of the vehicle from the actual vertical displacement of the vehicle to obtain a vehicle vertical displacement error, subtracting the ideal pitch angle of the vehicle from the actual pitch angle of the vehicle to obtain a vehicle pitch angle error, and subtracting the ideal roll angle of the vehicle from the actual roll angle of the vehicle to obtain a vehicle roll angle error; Constructing a vehicle vertical motion extended state observer, a vehicle pitch motion extended state observer and a vehicle roll motion extended state observer; Based on the vehicle vertical displacement error, in combination with the vehicle vertical motion extended state observer, the vehicle vertical motion lumped disturbance is obtained; based on the vehicle pitch angle error, in combination with the vehicle pitch motion extended state observer, the vehicle pitch motion lumped disturbance is obtained; based on the vehicle roll angle error, in combination with the vehicle roll motion extended state observer, the vehicle roll motion lumped disturbance is obtained; Based on the lumped disturbance of the vertical motion of the vehicle and the vertical displacement error of the vehicle, an ideal control force in the vertical direction of the vehicle is obtained; based on the lumped disturbance of the pitch motion of the vehicle and the pitch angle error of the vehicle, an ideal control force in the pitch direction of the vehicle is obtained; based on the lumped disturbance of the roll motion of the vehicle and the roll angle error of the vehicle, an ideal control force in the roll direction of the vehicle is obtained; The ideal control force in the vertical direction of the vehicle, the ideal control force in the pitch direction of the vehicle and the ideal control force in the roll direction of the vehicle are decoupled to obtain the active dynamic force of each suspension of the vehicle.

2. The vehicle active suspension control method considering the influence of road slope according to claim 1, characterized in that: The expression of the vehicle vertical motion extended state observer is: The expression of the vehicle pitch motion extended state observer is: The expression of the vehicle roll motion extended state observer is: Where: e z is the vehicle vertical displacement error, is the vehicle pitch angle error, e θ is the vehicle roll angle error, b z1 =3ω z , ω z is the first positive vertical parameter, is the first positive parameter of pitch, b θ1 =3ω θ , ω θ is the first positive roll parameter, γ z is the second positive vertical parameter, is the second positive parameter of pitch, γ θ is the second positive parameter of roll, m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x The nominal value of is the first positive parameter, σ xy is the second positive parameter, 0<σ xy <1, δ is the design parameter, δ>0, y=1,2,3,U z (t) is the output force of the vertical motion controller, is the output force of the pitch motion controller, U θ (t) is the output force of the roll motion controller, and sign is the sign function.

3. The vehicle active suspension control method considering the influence of road slope according to claim 1, characterized in that: The ideal control force expression of the vehicle in the vertical direction is: The ideal control force expression of the vehicle pitch direction is: The ideal control force expression of the vehicle roll direction is: Where: U z It is the ideal control force in the vertical direction of the vehicle. k z is the vertical control gain, is the pitch control gain, k θ is the roll control gain, k z >0, k θ >0,m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x Nominal value.

4. The vehicle active suspension control method considering the influence of road slope according to claim 1, characterized in that: The decoupling process of the active motion force of each suspension is: Where: u i ′ represents the ideal force of the i-th suspension, l f Indicates the distance from the front axle to the vehicle's center of mass, l m Indicates the distance from the center axis to the center of mass of the vehicle, l r represents the distance between the rear axle and the center of mass of the vehicle, B represents the wheelbase of the left and right wheels, and inv represents the inverse matrix.

5. The vehicle active suspension control method considering the influence of road slope according to claim 1, characterized in that: The nonlinear spring force expression of the i-th suspension is: P si =k si (With bi -With wi )+k Nli (With wi -With bi ) 3 ; The nonlinear damping force expression of the i-th suspension is: The wheel elastic force expression at the i-th suspension is: P ti =k ti (With wi -With ri ); The wheel damping force expression at the i-th suspension is: Where: z bi is the vertical displacement of the connection between the ith suspension and the vehicle body, is the vertical velocity of the connection between the ith suspension and the vehicle body, k si is the linear spring coefficient of the ith suspension, k Nli is the nonlinear spring coefficient of the ith suspension, c si is the linear damping coefficient of the ith suspension, c Nli is the nonlinear damping coefficient of the ith suspension, k ti is the wheel spring coefficient at the ith suspension, c tdi is the wheel damping coefficient at the ith suspension, z ri is the road-induced vertical displacement of the wheel at the ith suspension, is the road-excited vertical velocity of the wheel at the ith suspension.

6. A vehicle active suspension control system taking into account the influence of road slope, characterized in that: It includes: A model building module is used to build an active suspension dynamics model and an ideal reference model of a three-axle vehicle taking into account the influence of road slope; the three axles of a three-axle vehicle are the front axle, the middle axle and the rear axle; The active suspension dynamics model is: The ideal reference model is: Where: m b is the mass of the three-axle vehicle, z b is the actual vertical displacement of the three-axle vehicle, is the actual vertical acceleration of the three-axle vehicle, P si is the nonlinear spring force of the ith suspension, N is the total number of suspensions, P di is the nonlinear damping force of the ith suspension, P ti is the wheel elastic force at the ith suspension, P tdi is the wheel damping force at the i-th suspension, d1 is the vertical disturbance, u i is the actual force input to the i-th suspension, J x is the moment of inertia of the vehicle body in the roll direction, J y is the moment of inertia of the vehicle body in the pitch direction, is the actual pitch angle of the vehicle, l Bi is the distance between the wheel at the ith suspension and the longitudinal centerline of the vehicle body, θ b is the actual roll angle of the vehicle, h b is the height of the vehicle's center of mass, is the vehicle body pitch angular acceleration, is the body roll angular acceleration, d2 is the pitch disturbance, d3 is the roll disturbance, l ei is the distance between the wheel at the ith suspension and the transverse centerline of the vehicle body, m wi is the unsprung mass at the ith suspension, z wi is the displacement of the unsprung mass at the ith suspension, z bd is the ideal reference vertical displacement, is the ideal reference vertical acceleration, is the ideal reference pitch angle, is the ideal reference pitch angle acceleration, θ bd is the ideal reference roll angle, is the ideal reference roll angle acceleration, c skyi is the ideal ceiling damping coefficient at the ith suspension, is the vertical displacement of the connection between the ith suspension and the vehicle body, c groundi is the ideal floor shed damping coefficient at the ith suspension, is the vertical motion speed of the wheel at the i-th suspension; A parameter acquisition module, used for obtaining the actual vertical displacement of the vehicle, the actual pitch angle of the vehicle and the actual roll angle of the vehicle based on the suspension dynamics model; Based on the ideal reference model, an ideal vertical displacement of the vehicle, an ideal pitch angle of the vehicle and an ideal roll angle of the vehicle are obtained; a difference module, configured to obtain a vehicle vertical displacement error by subtracting the ideal vehicle vertical displacement from the actual vehicle vertical displacement, obtain a vehicle pitch angle error by subtracting the ideal vehicle pitch angle from the actual vehicle pitch angle, and obtain a vehicle roll angle error by subtracting the ideal vehicle roll angle from the actual vehicle roll angle; An observer module is used to construct an expanded state observer for the vertical motion of a vehicle, an expanded state observer for the pitch motion of a vehicle, and an expanded state observer for the roll motion of a vehicle; A disturbance module, configured to obtain a vehicle vertical motion lumped disturbance based on the vehicle vertical displacement error in combination with a vehicle vertical motion extended state observer, obtain a vehicle pitch motion lumped disturbance based on the vehicle pitch angle error in combination with a vehicle pitch motion extended state observer, and obtain a vehicle roll motion lumped disturbance based on the vehicle roll angle error in combination with a vehicle roll motion extended state observer; A control force module, used for obtaining an ideal control force in the vertical direction of the vehicle based on the lumped disturbance of the vertical motion of the vehicle and the vertical displacement error of the vehicle, obtaining an ideal control force in the pitch direction of the vehicle based on the lumped disturbance of the pitch motion of the vehicle and the pitch angle error of the vehicle, and obtaining an ideal control force in the roll direction of the vehicle based on the lumped disturbance of the roll motion of the vehicle and the roll angle error of the vehicle; The actuation force module is used to decouple the ideal control force in the vertical direction of the vehicle, the ideal control force in the pitch direction of the vehicle and the ideal control force in the roll direction of the vehicle to obtain the active actuation force of each suspension of the vehicle.

7. The vehicle active suspension control system considering the influence of road slope according to claim 6, characterized in that: The expression of the vehicle vertical motion extended state observer is: The expression of the vehicle pitch motion extended state observer is: The expression of the vehicle roll motion extended state observer is: Where: e z is the vehicle vertical displacement error, is the vehicle pitch angle error, e θ is the vehicle roll angle error, b z1 =3ω z , ω z is the first positive vertical parameter, is the first positive parameter of pitch, b θ1 =3ω θ , ω θ is the first positive roll parameter, γ z is the second positive vertical parameter, is the second positive parameter of pitch, γ θ is the second positive parameter of roll, m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x The nominal value of is the first positive parameter, σ xy is the second positive parameter, 0<σ xy <1, δ is the design parameter, δ>0, y=1,2,3,U z (t) is the output force of the vertical motion controller, is the output force of the pitch motion controller, U θ (t) is the output force of the roll motion controller, and sign is the sign function.

8. The vehicle active suspension control system considering the influence of road slope according to claim 6, characterized in that: The ideal control force expression of the vehicle in the vertical direction is: The ideal control force expression of the vehicle pitch direction is: The ideal control force expression of the vehicle roll direction is: Where: U z It is the ideal control force in the vertical direction of the vehicle. k z is the vertical control gain, is the pitch control gain, k θ is the roll control gain, k z >0, k θ >0,m bn is m b The nominal value, J yn For J y The nominal value, J xn For J x Nominal value.

9. The vehicle active suspension control system considering the influence of road slope according to claim 6, characterized in that: The decoupling process of the active motion force of each suspension is: Where: u′ i represents the ideal force of the ith suspension, l f Indicates the distance from the front axle to the center of mass of the vehicle, l m Indicates the distance from the center axis to the center of mass of the vehicle, l r represents the distance between the rear axle and the center of mass of the vehicle, B represents the wheelbase of the left and right wheels, and inv represents the inverse matrix.

10. The vehicle active suspension control system considering the influence of road slope according to claim 6, characterized in that: The nonlinear spring force expression of the i-th suspension is: P si =k si (With bi -With wi )+k Nli (With wi -With bi ) 3 ; The nonlinear damping force expression of the i-th suspension is: The wheel elastic force expression at the i-th suspension is: P ti =k ti (With wi -With ri ); The wheel damping force expression at the i-th suspension is: Where: z bi is the vertical displacement of the connection between the ith suspension and the vehicle body, is the vertical velocity of the connection between the ith suspension and the vehicle body, k si is the linear spring coefficient of the ith suspension, k Nli is the nonlinear spring coefficient of the ith suspension, c si is the linear damping coefficient of the ith suspension, c Nli is the nonlinear damping coefficient of the ith suspension, k ti is the wheel spring coefficient at the ith suspension, c tdi is the wheel damping coefficient at the ith suspension, z ri is the road-induced vertical displacement of the wheel at the ith suspension, is the road-excited vertical velocity of the wheel at the ith suspension.

Images