Active vibration reduction control method based on model predictive control

Abstract

The invention discloses an active vibration reduction control method based on model predictive control, aims to improve vibration conditions of a hybrid vehicle under different driving conditions, and specifically comprises the following steps: (1) establishing an eight-degree-of-freedom vibration kinetic equation; and (2) an eight-degree-of-freedom vibration kinetic equation which is difficult to be directly applied to controller design is simplified into a three-degree-of-freedom torsional vibration model, and a discrete equation is modified into an incremental equation, so that the static error of the system is reduced, and accumulative errors are avoided. According to the invention, a comprehensive control target of balancing comfort and dynamic property is designed, and finally, the riding comfort is improved on the basis of ensuring the dynamic property.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle comfort, and specifically relates to an active vibration damping control method based on model predictive control. Background Technique

[0002] Vibration damping control of the transmission system is crucial for ensuring the ride comfort of vehicles. At present, common active vibration damping control algorithms mainly include PID control, sliding mode control (SMC), LQR control, and model predictive control (MPC), etc. Among them, as a type of controller that solves constrained optimization problems by rolling optimization, MPC has outstanding advantages in solving vibration damping control problems. However, the research on motion control of traditional MPC fails to well design the comprehensive control objectives of comfort and dynamic performance, which may cause power shortage of the vehicle under certain working conditions. Simplify the eight-degree-of-freedom torsional vibration model, design the comprehensive control objective that balances comfort and dynamic performance, further modify the discrete state equation into an incremental state equation, reduce the system static error, and finally realize the active vibration damping control of the transmission system.

[0003] Some existing patents, such as the invention patent with the patent number CN116691362A, propose a vehicle and its control method for active vibration damping and a vehicle controller. The invention patent with the patent number CN113859216A proposes a multi-condition active vibration damping control method for a hybrid power system based on vibration damping waveforms. The former obtains the rotational speed of the motor through the motor and the motor controller, and obtains the active vibration damping torque according to the rotational speed fluctuation value, the active vibration damping adjustment coefficient, and the active vibration damping limit torque. The latter online and real-time judges the state and working condition points of the hybrid power system, and switches the vibration damping waveform in real time as the working condition changes. Neither of them comprehensively designs the objectives of dynamic performance and comfort. Summary of the Invention

[0004] The present invention aims to improve the ride comfort of vehicles under different driving conditions, and proposes an active vibration damping control method based on model predictive control. This method first establishes an eight-degree-of-freedom torsional vibration model, then simplifies the torsional vibration model, and then discretizes the established model. Further modify the above discrete state equation into an incremental state equation, reduce the system static error, avoid cumulative error, design the comprehensive control objective that balances comfort and dynamic performance, and realize the improvement of ride comfort on the basis of ensuring dynamic performance.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0006] 1. An active vibration damping control method based on model predictive control, characterized by including the following steps:

[0007] S1: Establish a torsional vibration dynamics equation system:

[0008]

[0009] Among them, J1 is the equivalent inertia of the crankshaft and accessories, the inertia of the flywheel, and the inertia of the active part of the clutch. J2 is the inertia of the clutch driven disc hub. J3 is the inertia of the drive motor rotor. J4 is the inertia of the first shaft and the intermediate shaft assembly of the transmission. J5 is the inertia of the second shaft assembly of the transmission. J6 is the inertia of the main reducer, differential, and 2 * 1 / 2 half shafts. J7 is the inertia of the 2 * 1 / 2 half shafts and the wheels. J8 is the equivalent inertia of the vehicle body. θ1 - θ8 are the torsional angular displacements of each inertia respectively, are the torsional angular velocities of each inertia respectively, are the torsional angular accelerations of each inertia respectively, T e is the engine excitation torque, T m is the motor excitation torque, T L is the total vehicle resistance torque, i g is the transmission ratio, i0 is the main reduction ratio, k 12 is the torsional stiffness of the clutch, k 23 is the torsional stiffness between the clutch and the motor rotor, k 34 is the torsional stiffness of the first shaft of the transmission, k 45 is the torsional stiffness of the second shaft and the intermediate shaft of the transmission, k 56 is the torsional stiffness of the shaft section of the drive shaft assembly, k 67 is the torsional stiffness of the rear axle half shaft, k 78 is the torsional stiffness of the drive wheel, c 12 is the damping of the clutch shock absorber, c 78 is the wheel damping;

[0010] S2: Simplify the torsional vibration model, establish the state - space equation and discretize it. The specific steps for designing the comprehensive control objective of balancing comfort and dynamic performance are as follows:

[0011] S21: Simplify the torsional vibration model:

[0012]

[0013] Among them,

[0014] Δθ1 = θ1 - θ2, i = i g i0;

[0015] S22: Establish the expression of the transmission system state - space equation as:

[0016]

[0017] Among them, x = [ω1 Δθ1 ω2 Δθ2 ω3] T , u = Tm , d = [T e 0 0 0T L T ,

[0018] Δθ2 = θ2 - θ3,

[0019]

[0020] Discretize the state - space equation:

[0021]

[0022] where,

[0023] Modify the above - mentioned discrete - state equation into an incremental - state equation:

[0024]

[0025] where I is a 5×5 identity matrix, t s is the sampling period, Δx(k)=x(k)-x(k - 1), Δu(k)=u(k)-u(k - 1), Δd(k)=d(k)-d(k - 1);

[0026] The prediction model is as follows:

[0027] Y(k + 1|k)=S x Δx(k)+S u ΔU(k)+S d Δd(k)+I c y(k) (6)

[0028] where,

[0029]

[0030] The objective function:

[0031]

[0032] where, E p (k + 1|k)= - S x Δx(k)-S d Δd(k)-I c y(k), W y = diag{w y …w y} p×1 , W​u = diag{w u … w u} u×1 ;

[0033] Constraint conditions:

[0034]

[0035] Wherein, is the lower limit value of the engine torque, is the upper limit value of the engine torque, is the lower limit value of the engine torque change rate, is the upper limit value of the engine torque change rate.

[0036] Compared with the prior art, the advantages of the present invention are:

[0037] The active vibration damping control method based on model prediction according to the present invention establishes a reasonable simplified torsional vibration model for control, modifies the discrete state equation into an incremental state equation, reduces the system static error, avoids cumulative error, designs a comprehensive control target that balances comfort and dynamic performance, and improves the riding comfort on the premise of ensuring dynamic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below with reference to the drawings and embodiments:

[0039] Figure 1 is a flowchart of an active vibration damping control method based on model prediction according to the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0041] The present invention will be further described below with reference to the drawings.

[0042] Referring to Figure 1 , the present invention provides an active vibration damping control method based on model prediction, which specifically includes the following steps:

[0043] SS1: Establish a torsional vibration dynamic equation set:

[0044]

[0045] Among them, J1 is the equivalent inertia of the crankshaft and accessories, the inertia of the flywheel, and the inertia of the active part of the clutch. J2 is the inertia of the clutch driven disc hub. J3 is the inertia of the drive motor rotor. J4 is the inertia of the first shaft and the intermediate shaft assembly of the transmission. J5 is the inertia of the second shaft assembly of the transmission. J6 is the inertia of the main reducer, differential, and 2*1 / 2 half shafts. J7 is the inertia of the 2*1 / 2 half shafts and the wheels. J8 is the equivalent inertia of the vehicle body. θ1-θ8 are the torsional angular displacements of each inertia respectively, are the torsional angular velocities of each inertia respectively, are the torsional angular accelerations of each inertia respectively, T e is the engine excitation torque, T m is the motor excitation torque, T L is the vehicle resistance torque, i g is the transmission ratio, i0 is the main reduction ratio, k 12 is the torsional stiffness of the clutch, k 23 is the torsional stiffness between the clutch and the motor rotor, k 34 is the torsional stiffness of the first shaft of the transmission, k 45 is the torsional stiffness of the second shaft and the intermediate shaft of the transmission, k 56 is the torsional stiffness of the shaft section of the drive shaft assembly, k 67 is the torsional stiffness of the rear axle half shaft, k 78 is the torsional stiffness of the drive wheel, c 12 is the damping of the clutch shock absorber, c 78 is the wheel damping;

[0046] S2: Simplify the torsional vibration model, establish the state space equation and discretize it, and design the comprehensive control objective of balancing comfort and dynamic performance. The specific steps are as follows:

[0047] S21: Simplify the torsional vibration model:

[0048]

[0049] Among them,

[0050] Δθ1 = θ1 - θ2, i = i g i0;

[0051] S22: Establish the state space equation expression of the transmission system as:

[0052]

[0053] Among them, x = [ω1 Δθ1 ω2 Δθ2 ω3] T , u = T m , d = [T e0 0 0T L T , Δθ2 = θ2 - θ3,

[0054]

[0055]

[0056] Discretize the state - space equation:

[0057]

[0058] where,

[0059] Modify the above - mentioned discrete - state equation into an incremental - state equation:

[0060]

[0061] where I is a 5×5 identity matrix, t s is the sampling period, Δx(k)=x(k)-x(k - 1), Δu(k)=u(k)-u(k - 1), Δd(k)=d(k)-d(k - 1);

[0062] The prediction model is as follows:

[0063] Y(k + 1|k)=S x Δx(k)+S u ΔU(k)+S d Δd(k)+I c y(k) (6)

[0064] where,

[0065]

[0066] Objective function:

[0067]

[0068] where,

[0069] E p (k + 1|k)= - S x Δx(k)-S d Δd(k)-I c y(k), W y =diag{w y …w y} p×1 ,​

[0070] W u = diag{w u …w u} u×1 ;

[0071] Constraint conditions:

[0072]

[0073] wherein, is the lower limit value of the engine torque, is the upper limit value of the engine torque, is the lower limit value of the engine torque change rate, is the upper limit value of the engine torque change rate.

[0074] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An active vibration damping control method based on model predictive control, characterized in that, The following steps are involved: S1: Establish the torsional vibration dynamics equations: Among them, J1 is the equivalent inertia of the crankshaft and accessories, the inertia of the flywheel, and the inertia of the active part of the clutch; J2 is the inertia of the clutch driven disc hub; J3 is the inertia of the drive motor rotor; J4 is the inertia of the first shaft and the intermediate shaft assembly of the transmission; J5 is the inertia of the second shaft assembly of the transmission; J6 is the inertia of the main reducer, differential, and 2*1 / 2 half shafts; J7 is the inertia of the 2*1 / 2 half shafts and wheels; J8 is the equivalent inertia of the vehicle body; θ1-θ8 are the torsional angular displacements of each inertia respectively, are the torsional angular velocities of each inertia respectively, are the torsional angular accelerations of each inertia respectively, T e is the engine excitation torque, T m is the motor excitation torque, T L is the vehicle resistance torque, i g is the transmission ratio, i0 is the main reduction ratio, k 12 is the torsional stiffness of the clutch, k 23 is the torsional stiffness between the clutch and the motor rotor, k 34 is the torsional stiffness of the first shaft of the transmission, k 45 is the torsional stiffness of the second shaft and the intermediate shaft of the transmission, k 56 is the torsional stiffness of the shaft section of the drive shaft assembly, k 67 is the torsional stiffness of the rear axle half shaft, k 78 is the torsional stiffness of the drive wheel, c 12 is the damping of the clutch shock absorber, c 78 is the wheel damping; S2: Simplify the torsional vibration model, establish and discretize the state-space equation, and design a comprehensive control target that balances comfort and dynamics. The specific steps are as follows: S21: Simplify the torsional vibration model: Among them, Δθ1=θ1-θ2,i=i g i0; S22: Establish the state space equation of the transmission system as follows: where x = [ω1Δθ1 ω2Δθ2 ω3] T , u = T m , d = [T e 000T L T , , Δθ2 = θ2 - θ3,​ Discretize the state-space equations: Among them, The above discrete state equation is further modified into the incremental state equation: Where I is the 5×5 identity matrix, t s is the sampling period, Δx(k)=x(k)-x(k-1), Δu(k)=u(k)-u(k-1), Δd(k)=d(k)-d(k-1); The prediction model is as follows: Y(k+1|k)=S x Δx(k)+S u ΔU(k)+S d Δd(k)+I c y(k) (6) Among them, Objective function: Among them, E p (k + 1|k) = -S x Δx(k) - S d Δd(k) - I c y(k), W y = diag{w y … w y} p×1 , W u = diag{w u … w u} u×1 ; Constraints: Among them, is the lower limit value of the engine torque, is the upper limit value of the engine torque, is the lower limit value of the engine torque change rate, is the upper limit value of the engine torque change rate.

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