Automobile stability coordination control method considering motor driving energy consumption analysis and driving anti-slip judgment

Abstract

The invention provides an automobile stability coordination control method based on motor driving energy consumption analysis and driving anti-slip judgment, which comprises the following steps that: firstly, a vehicle control unit inputs vehicle driving state information based on driver operation; then, through motor driving energy consumption analysis, traversing decomposition is performed on a total driving torque demand and a total yawing torque demand based on an orthogonal test method, an optimal torque range of each wheel is obtained offline, economical efficiency, dynamics and stability optimization targets are set on the basis, sequential quadratic programming online rapid optimization is performed, and finally, the optimal torque range is obtained. Information such as the wheel speed and the vehicle speed of each wheel is collected, the real-time longitudinal slip rate of each wheel is calculated, the vehicle slip state is judged in combination with the relation between the vehicle adhesion coefficient and the typical road adhesion coefficient, and a stability coordination control method is designed. According to the method, energy consumption analysis, torque distribution optimization and driving anti-slip judgment are fused into automobile stability control, energy consumption is effectively reduced, and the automobile stability and the slip control precision are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of automotive electrical stability control, and specifically relates to an automotive stability coordinated control method considering motor drive energy consumption analysis and drive anti-skid determination. Background Art

[0002] As an important solution for energy conservation and environmental protection, the development of electric vehicles is a key way to address energy consumption and environmental pollution. How to develop a reasonable stability control algorithm to coordinate motor drive energy consumption and drive anti-skid under different driving conditions to fully exert its energy-saving potential and stability is an important topic in the field of electric vehicles and is of great significance for improving the overall performance of vehicles and promoting safe travel.

[0003] Some existing patents, such as the invention patent with the patent number CN113978263A, designed an electric vehicle stability control method that integrates drive wheel anti-skid and torque optimization. According to the vehicle's total demand torque, additional yaw torque, and tire lateral force, vertical force, and the rotational speeds of the two rear wheels, the demand torques of the two rear-wheel hub motors are output to control the slip ratios of the left and right drive wheels to keep them near the optimal slip ratio. However, this patent lacks consideration of motor energy consumption. The invention patent with the patent number CN109927704B proposed an automotive wheel drive anti-skid control method that selects different working modes based on the slip ratios of each drive wheel of the vehicle. It can not only improve the starting and accelerating performance of the vehicle on split roads and low adhesion coefficient roads but also further ensure driving comfort and speed continuity during the starting and accelerating process. However, the research on different slip states is not deep enough.

[0004] Some existing fixed rules or simple optimization algorithms are difficult to dynamically adapt to complex driving conditions, and automotive stability control algorithms need to consider multiple objectives such as energy consumption, dynamic performance, and slip control accuracy at the same time. Under complex working conditions, there may be mutual constraints between these objectives, increasing the complexity of the control system. Therefore, how to develop an automotive stability coordinated control method with multi-objective optimization, self-learning, and working condition adaptability capabilities to optimize with high precision, effectively reduce energy consumption, improve vehicle stability and slip control accuracy is a difficult point to be solved. Summary of the Invention

[0005] The present invention proposes an automotive stability coordinated control method considering motor drive energy consumption analysis and drive anti-skid determination. Aiming at the problems of high energy consumption, insufficient stability, and low slip control accuracy of the existing technology under complex working conditions, the vehicle controller calculates the initial drive torque and yaw torque requirements, combines energy consumption analysis to optimize wheel torque distribution, and determines the vehicle slip state according to the real-time slip ratio and adhesion coefficient, designs a stability coordinated control strategy to achieve stable tracking of vehicle state variables and improve comprehensive performance.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A vehicle stability coordinated control method considering motor drive energy consumption analysis and drive anti-skid determination. The drive system consists of a power battery, a battery energy management system, a motor, a motor controller, a reducer, and wheels. The motor controller controls the motor to drive the wheels through the reducer, and the motor is powered by the power battery driven by the battery energy management system. The control method includes:

[0008] S1: The vehicle controller calculates the initial total drive torque demand T all and the total yaw moment demand M all :

[0009] (T all , M all ) = f(v, SOC, θ steer , p acc , p brk ) (1)

[0010] In the formula, v is the vehicle speed, SOC is the state of charge of the battery, θ steer is the steering wheel input, p acc is the accelerator pedal opening, and p brk is the brake pedal opening.

[0011] S2: Through motor drive energy consumption analysis, based on the orthogonal test method, the total drive torque demand T all and the total yaw moment demand M all are traversed and decomposed, and the optimal torque range of each wheel is obtained offline;

[0012] S3: Further online optimization is carried out on the basis of the offline optimal torque range. Under the condition of meeting the system constraints, the optimization objectives of economy, dynamics, and stability are set, and online rapid optimization of sequential quadratic programming is carried out to decompose the initial total drive torque demand and the total yaw moment demand into the target torques of each wheel;

[0013] S4: On the basis of executing the target torques of each wheel, by collecting information such as the wheel speed and vehicle speed of each wheel, the real-time longitudinal slip ratio of each wheel is calculated, and combined with the relationship between the utilization adhesion coefficient of each vehicle and the typical road adhesion coefficient, the vehicle slip state is determined, including four cases of single-wheel slip, same-side double-wheel slip, opposite-side double-wheel slip, and multi-wheel slip, and a stability coordinated control method is designed.

[0014] Furthermore, the specific process of the online rapid optimization method in step S3 is as follows:

[0015] S31: Online optimization is carried out on the basis of the offline optimal torque range of the orthogonal test. The algorithm inputs include the total drive torque demand Tall 、Total yaw moment demand \(M\) all 、Parameters such as the vertical load of each wheel, road adhesion coefficient, and road gradient. The algorithm control variables are the torques \(T\) lf 、\(T\) rf 、\(T\) lr 、\(T\) rr (left front wheel, right front wheel, left rear wheel, right rear wheel). Select the vehicle speed \(v\) as the state variable, i.e., \(x = v\), then the nonlinear state - space equation can be set as:

[0016]

[0017] S32: Define the objective function as:

[0018]

[0019] In the formula, is the energy consumption of the electric drive system (integral of the motor power \(P\) motor ) objective function, is the energy consumption objective function of wheel longitudinal slip (integral of the power \(P\) motor at the wheel and the longitudinal slip ratio \(S\) i ), is the yaw - rate tracking error objective function (sum of the squares of the error \(\omega\) act_i between the actual yaw rate and the desired yaw rate \(\omega\) ref_i ), \(k\) 1 、\(k\) 2 are the weight coefficients of the objective function.

[0020] In addition to satisfying the motor speed - torque constraints, it is also necessary to satisfy the adhesion ellipse constraint:

[0021]

[0022] In the formula, \(\mu\) is the friction coefficient, \(F\) i,x is the lateral tire force, \(F\) i,y is the longitudinal tire force, \(F\) i,z is the vertical tire force.

[0023] The driving force is constrained by the tire friction circle as:

[0024]

[0025] S33: Use the Sequential Quadratic Programming (SQP) algorithm to solve the above - mentioned nonlinear programming problem, and apply the first element of the optimal control input sequence to the system as the optimal control quantity \(T\) lf 、\(T\) rf 、\(T\) lr 、\(T\)rr 。

[0026] Further, the specific process of the stability coordination control method based on the slip state determination in step S4 is as follows:

[0027] S41: Collect information such as the wheel speed and vehicle speed of each wheel, and calculate the real-time longitudinal slip ratio S of each wheel i :

[0028]

[0029] In the formula, w is the rotational speed of the driving wheel, i is the serial number of the driving wheel, and r is the radius of the driving wheel.

[0030] S42: Determine the vehicle driving anti-slip state. When it is detected that the real-time longitudinal slip ratio S of each wheel i is less than the optimal slip ratio of the current road surface, define the flag bit M flag = 0, the vehicle does not need anti-slip control and responds to the optimal target T of the motor lf 、T rf 、T lr 、T rr ; when it is detected that the real-time longitudinal slip ratio S of each wheel i is greater than the optimal slip ratio of the current road surface, the vehicle needs anti-slip control. Distinguish four situations of single-wheel slip, same-side double-wheel slip, opposite-side double-wheel slip, and multi-wheel slip. The flag bit M flag is 1, 2, 3, and 4 respectively;

[0031] S43: Design the stability control method for different slip conditions:

[0032] (1) M flag = 1, that is, when single-wheel slip occurs, the control system quickly reduces the torque of the slipping wheel by ΔT i , so that the rotational speed of the driving wheel is maintained near the target rotational speed. To make the yaw moment relatively small, perform same-side torque transfer, that is, increase the torque of the non-slipping wheel on the same side by ΔT i , to meet the dynamic coordination requirements;

[0033] (2) M flag = 2, that is, when same-side double-wheel slip occurs, the driving torque of the slipping wheel is quickly reduced, and the rotational speed is maintained near the target rotational speed. Coordinate to increase the torque of the opposite-side wheels, make up for the torque lost due to driving anti-slip, and proportionally increase the torque of the opposite-side double wheels according to the remaining torque margin until the driving torque reaches the upper limit;

[0034] (3) M flag= 3, that is, when the two wheels on the opposite side slip, the driving torque of the slipping wheels decreases rapidly, the wheel speed is maintained near the target wheel speed, the torque of the wheels on the same side is coordinated to increase, and the torque of the two wheels on the same side is increased proportionally according to the remaining torque margin until the driving torque reaches the upper limit;

[0035] (4)M flag = 4, that is, when multiple wheels slip, the driving torque of the slipping wheels decreases rapidly, the wheel speed is maintained near the target wheel speed, the priority is given to the stability coordination requirement, and the remaining non-slipping wheels are reduced to the torque maintained by the slipping wheels.

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

[0037] 1. A vehicle stability coordination control method based on motor drive energy consumption analysis and drive anti-skid determination proposed by the present invention solves the problems of high energy consumption, insufficient stability and low anti-skid control accuracy under complex working conditions, and provides a new solution for vehicle stability control.

[0038] 2. The vehicle stability coordination control method based on motor drive energy consumption analysis and drive anti-skid determination described in the present invention integrates energy consumption analysis, torque distribution optimization and drive anti-skid determination into the control framework. Through the orthogonal test method and sequential quadratic programming for online rapid optimization, the accurate distribution of the target torque of each wheel is realized, and the economy, dynamic performance and stability of the vehicle under complex working conditions are significantly improved.

[0039] 3. The vehicle stability coordination control method based on motor drive energy consumption analysis and drive anti-skid determination described in the present invention designs a drive anti-skid determination method based on the real-time longitudinal slip ratio. By combining the vehicle adhesion coefficient with the relationship of the typical road surface adhesion coefficient, the vehicle slip state is accurately determined, and a stability coordination control strategy is designed, which effectively improves the anti-skid control accuracy and driving safety of the vehicle, and provides important guiding significance for vehicle stability control under complex working conditions. Description of the Drawings

[0040] Figure 1 Schematic diagram of the electric vehicle system structure used in the embodiment;

[0041] Figure 2 Flowchart of the stability control method considering motor drive energy consumption and drive anti-skid determination used in the embodiment;

[0042] Figure 3 Basic schematic diagram of the vehicle controller algorithm used in the embodiment;

[0043] Figure 4 Flowchart of the orthogonal test method for solving the optimal torque range of the discrete motor used in the embodiment;

[0044] Figure 5Flowchart for solving the objective function sequence quadratic programming algorithm used in the embodiment;

[0045] Figure 6 Flowchart for the vehicle slip state determination and stability coordinated control method used in the embodiment;

[0046] Annotations in the figure: 1. Power battery, 2. Battery energy management system, 3. Motor, 4. Motor controller, 5. Reducer, 6. Wheel. Specific implementation manner

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described examples are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] Embodiment

[0049] An automotive stability coordinated control method based on motor drive energy consumption analysis and drive anti-skid determination. The transmission system of the vehicle is as Figure 1 shown, and it consists of a power battery 1, a battery energy management system 2, a motor 3, a motor controller 4, a reducer 5, and a wheel 6. The motor controller 4 controls the motor 3 to drive the wheel 6 through the reducer 5, and the motor 3 is powered by the power battery driven by the battery energy management system 2.

[0050] Schematic diagram of the flow of the automotive stability coordinated control method based on motor drive energy consumption analysis and drive anti-skid determination is as Figure 2 shown. First, the vehicle controller calculates the initial total drive torque demand and the total yaw moment demand based on the driver's operation input and the vehicle driving state information; then, through motor drive energy consumption analysis, based on the orthogonal test method, the total drive torque demand and the total yaw moment demand are traversed and decomposed, and the optimal torque range of each wheel is obtained offline. On this basis, economic, dynamic, and stability optimization objectives are set, and sequential quadratic programming is used for online rapid optimization to decompose the initial total drive torque demand and the total yaw moment demand into the target torques of each wheel; finally, information such as the wheel speed and vehicle speed of each wheel is collected, the real-time longitudinal slip ratio of each wheel is calculated, and the vehicle slip state is determined in combination with the relationship between the vehicle adhesion coefficient and the typical road surface adhesion coefficient, and a stability coordinated control method is designed. This stability coordinated control method specifically includes:

[0051] S1: The vehicle controller calculates the initial total drive torque demand T all and the total yaw moment demand M all , as Figure 3 shown:

[0052] (T all , M all ) = f(v, SOC, θ steer , p acc , p brk ) (1)

[0053] Wherein, v is the vehicle speed, SOC is the state of charge of the battery, θ steer is the steering wheel input, p acc is the accelerator pedal opening, p brk is the brake pedal opening.

[0054] S2: Through the analysis of the motor drive energy consumption, based on the orthogonal test method, the total drive torque demand T all and the total yaw moment demand M all are traversed and decomposed, and the optimal torque range of each wheel is obtained offline, as Figure 4 shown;

[0055] S3: Further online optimization is carried out on the basis of the offline optimal torque range. Under the condition of meeting the system constraints, the optimization objectives of economy, dynamics and stability are set, and the online rapid optimization of sequential quadratic programming is carried out, as Figure 5 shown, and the initial total drive torque demand and total yaw moment demand are decomposed into the target torques of each wheel; the specific implementation process is as follows:

[0056] S31: Online optimization is carried out on the basis of the orthogonal test offline optimal torque range. The algorithm inputs include the total drive torque demand T all , the total yaw moment demand M all , the vertical load of each wheel, the road adhesion coefficient, the road gradient and other parameter quantities. The algorithm control variables are the torques T lf , T rf , T lr , T rr (left front wheel, right front wheel, left rear wheel, right rear wheel). The vehicle speed v is selected as the state variable, that is, x = v, then the nonlinear state space equation can be set as:

[0057]

[0058] S32: Define the objective function as:

[0059]

[0060] Wherein, is the objective function of the energy consumption of the electric drive system (the integral of the motor power P motor ), is the objective function of the energy consumption of the wheel longitudinal slip (the integral of the power P motor at the wheel and the longitudinal slip ratio S i ), is the yaw rate tracking error objective function (the actual yaw rate ω act_i The error between the desired yaw rate and ref_i The sum of squares), k 1 , k 2 is the weight coefficient of the objective function.

[0061] In addition to satisfying the motor speed and torque constraints, the adhesion ellipse constraints must also be met:

[0062]

[0063] Where μ is the friction coefficient, F i,x is the lateral tire force, F i,y is the longitudinal tire force, F i,z is the vertical tire force.

[0064] The driving force is constrained by the tire friction circle as follows:

[0065]

[0066] S33: The above nonlinear programming problem is solved using the Sequence Quadratic Program (SQP) algorithm, and the first element of the optimal control input sequence is applied to the system as the optimal control quantity T required for the current task. lf , T rf , T lr , T rr .

[0067] S4: On the basis of executing the target torque of each wheel, by collecting information such as the wheel speed and vehicle speed of each wheel, the real-time longitudinal slip rate of each wheel is calculated, and the vehicle slip state is determined by combining the relationship between the adhesion coefficient of each vehicle and the adhesion coefficient of the typical road surface, including four situations: single-wheel slip, same-side double-wheel slip, opposite-side double-wheel slip, and multi-wheel slip, and a stability coordination control method is designed, such as Figure 6 The specific implementation process is as follows:

[0068] S41: Collect information such as wheel speed and vehicle speed of each wheel, and calculate the real-time longitudinal slip rate S of each wheel i :

[0069]

[0070] Where w is the driving wheel speed, i is the driving wheel number, and r is the driving wheel radius.

[0071] S42: Determine the vehicle driving anti-skid state. When the real-time longitudinal slip rate S of each wheel is detected, i When the slip rate is less than the optimal slip rate of the current road surface, the flag position M is definedflag = 0, the vehicle does not need to perform anti - slip control and responds to the optimal target torque T of the motor lf 、T rf 、T lr 、T rr ; When the real - time longitudinal slip ratio S of each wheel is detected i greater than the optimal slip ratio of the current road surface, the vehicle needs to perform anti - slip control, distinguishing four situations: single - wheel slip, same - side double - wheel slip, opposite - side double - wheel slip, and multi - wheel slip. The flag bit M flag is 1, 2, 3, and 4 respectively;

[0072] S43: Design stability control methods for different slip situations:

[0073] (1) M flag = 1, that is, when single - wheel slip occurs, the control system quickly reduces the torque of the slipping wheel by ΔT i , so that the driving wheel speed is maintained near the target wheel speed. To make the yaw moment relatively small, perform same - side torque transfer, that is, increase the torque of the non - slipping wheel on the same side by ΔT i , to meet the power coordination requirements;

[0074] (2) M flag = 2, that is, when same - side double - wheel slip occurs, the driving torque of the slipping wheels is quickly reduced, the wheel speed is maintained near the target wheel speed, coordinate to increase the torque of the opposite - side wheels, make up for the torque lost due to drive anti - slip, and proportionally increase the torque of the opposite - side double - wheels according to the remaining torque margin until the driving torque reaches the upper limit;

[0075] (3) M flag = 3, that is, when opposite - side double - wheel slip occurs, the driving torque of the slipping wheels is quickly reduced, the wheel speed is maintained near the target wheel speed, coordinate to increase the torque of the same - side wheels, and proportionally increase the torque of the same - side double - wheels according to the remaining torque margin until the driving torque reaches the upper limit;

[0076] (4) M flag = 4, that is, when multi - wheel slip occurs, the driving torque of the slipping wheels is quickly reduced, the wheel speed is maintained near the target wheel speed, prioritize the stability coordination requirements, and reduce the remaining non - slipping wheels to the torque for maintaining the slipping wheels.

[0077] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A vehicle stability coordination control method considering motor drive energy consumption analysis and drive anti-skid determination, characterized in that: The steps include: S1: The vehicle controller calculates the initial total drive torque demand T based on the driver input and vehicle driving status. all and the total yaw moment demand M all : (T all ,M all )=f(v,SOC,θ steer ,p acc ,p brk ) (1) Where v is the vehicle speed, SOC is the battery state of charge, θ steer is the steering wheel input, p acc is the accelerator pedal opening, p brk is the brake pedal opening; S2: Through the motor drive energy consumption analysis, the total drive torque requirement T is calculated based on the orthogonal test method. all and the total yaw moment demand M all Perform traversal decomposition to obtain the optimal torque range of each wheel offline; S3: Further online optimization is performed based on the offline optimal torque range. Under the condition of satisfying system constraints, the optimization goals of economy, dynamics and stability are set, and online rapid optimization of sequential quadratic programming is performed to decompose the initial total driving torque demand and total yaw moment demand into the target torque of each wheel. S4: On the basis of executing the target torque of each wheel, the real-time longitudinal slip rate of each wheel is calculated by collecting information such as the wheel speed and vehicle speed of each wheel, and the vehicle slip state is determined in combination with the relationship between the adhesion coefficient of each vehicle and the adhesion coefficient of the typical road surface, including four situations: single-wheel slip, same-side double-wheel slip, opposite-side double-wheel slip and multi-wheel slip, and a stability coordination control method is designed.

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