A commercial vehicle acceleration closed-loop control method considering load and running resistance

Abstract

The application is suitable for the technical field of vehicle acceleration control, and provides a commercial vehicle acceleration closed-loop control method considering load and running resistance, which comprises the following steps: step 1, driving system dynamics modeling; step 2, driving process dynamic response transfer function modeling; step 3, acceleration dynamic response control parameter determination; and step 4, acceleration adaptive closed-loop control. The method derives the dynamic response transfer function of the driving process by constructing the driving system dynamics model; after the key parameters most sensitive to the acceleration dynamic response are determined through analysis, the method of combining feedforward control and closed-loop feedback adaptive control is adopted to realize the closed-loop adaptive control of the acceleration dynamic response. When the vehicle mass and the running resistance change, the method can effectively guarantee the consistency of the acceleration dynamic response, and further improve the driving quality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vehicle acceleration control, and particularly relates to a commercial vehicle acceleration closed-loop control method considering load and running resistance. BACKGROUND

[0002] In recent years, the commercial vehicle industry in China has developed rapidly, and the production and sales volume ranks first in the world. The user demand of commercial vehicles has also changed from pure reliability and durability to driving quality such as control and comfort, and improving the driving quality of vehicles has become one of the core elements to improve product competitiveness. During the operation of commercial vehicles, due to the influence of loading and unloading goods, road conditions and climate environment, the vehicle often faces complex working conditions with significant changes in load, road slope and wind resistance, resulting in obvious differences in acceleration response during acceleration. For example, the vehicle is prone to "forward jump" when starting under no load, and is slow under heavy load or climbing conditions. The inconsistency of such acceleration response not only affects the driving experience, but also may interfere with the operation judgment of the driver, and further affect the driving safety.

[0003] The Chinese invention patent with the publication number CN120663927A proposes a "vehicle starting acceleration control method, device, electronic equipment and storage medium". The method determines the starting safety level by integrating the driver operation level, vehicle driving mode and starting environment information, and matches the corresponding starting acceleration accordingly, to improve the smoothness and safety of starting. The scheme mainly focuses on multi-dimensional data fusion and safety level matching strategy design, and is only applicable to the starting stage, and does not fully consider the influence of changes in vehicle load and running resistance on acceleration control.

[0004] The Chinese invention patent with the publication number CN113147734B proposes a "closed-loop control method based on driver longitudinal acceleration intention", which constructs a nonlinear correspondence between the accelerator pedal and the expected acceleration by using information such as pedal opening, vehicle speed and actual acceleration, to reflect the acceleration demand of the driver. The method mainly focuses on the matching design of driving intention recognition and pedal mapping, and does not fully consider the influence of the consistency of acceleration dynamic response of commercial vehicles under large load changes and variable driving slope. SUMMARY

[0005] The purpose of the embodiment of the application is to provide a commercial vehicle acceleration closed-loop control method considering load and running resistance, which aims to solve the problems proposed in the above background.

[0006] The embodiment of the application is implemented as follows: a commercial vehicle acceleration closed-loop control method considering load and running resistance, comprising the following steps:

[0007] Step 1: modeling of the dynamics of the drive system;

[0008] Based on the overall vehicle configuration, establish a powertrain system model, a wheel rotation dynamics model, a tire model, and a longitudinal dynamics model, and integrate the models of each subsystem to form a complete longitudinal dynamics model of the whole vehicle.

[0009] Step 2: Modeling the dynamic response transfer function of the driving process;

[0010] Laplace transforms are performed on the dynamic models of each subsystem and the longitudinal dynamic model of the whole vehicle to obtain the input and output transfer functions of each subsystem, and these are combined to form the dynamic response transfer function of the whole vehicle driving process; at the same time, the parameters related to the acceleration dynamic response are determined.

[0011] Step 3: Determine the dynamic response control parameters for acceleration;

[0012] By analyzing the amplitude-frequency and phase-frequency characteristics of parameters related to acceleration dynamic response, the key parameters most sensitive to acceleration dynamic response are identified.

[0013] Step 4: Acceleration adaptive closed-loop control;

[0014] The system integrates feedforward control with closed-loop feedback adaptive control. An extended Kalman filter is used for parameter estimation and provided to the feedforward control. The feedforward control calculates the pre-compensation torque based on real-time operating conditions. The closed-loop feedback adaptive control corrects the feedforward deviation and ensures the dynamic response of acceleration by adjusting the control parameters in real time and performing differential filtering.

[0015] A further technical solution involves establishing, in step 1, a powertrain system model, a wheel rotational dynamics model, a tire model, and a longitudinal dynamics model based on the overall vehicle configuration; wherein, the powertrain system model is:

[0016] ;

[0017] In the formula, This is the actual torque. To meet the required torque, The torque response time constant, For time;

[0018] The driving torque at the wheel is:

[0019] ;

[0020] In the formula, The total transmission ratio is... The total transmission efficiency. The torque applied to the wheels by the powertrain;

[0021] The wheel rotation dynamics model is as follows:

[0022] ;

[0023] wherein, is the equivalent rotational inertia of the powertrain to the wheel end, is the wheel rotational speed, is the wheel rolling radius, is the tire longitudinal force;

[0024] The tire model is:

[0025] ;

[0026] wherein, is the tire longitudinal slip stiffness, is the slip ratio;

[0027] The slip ratio is:

[0028] ;

[0029] wherein, is the vehicle speed;

[0030] The vehicle longitudinal dynamics model is:

[0031] ;

[0032] wherein, is the vehicle mass, is the constant term of the resistance, is the linear speed-dependent resistance coefficient, is the quadratic speed-dependent resistance coefficient.

[0033] Further technical solutions, in the step 2, the Laplace transform is carried out on each subsystem dynamics model and the vehicle longitudinal dynamics model, the input and output transfer functions of each subsystem are obtained, and the whole vehicle driving process dynamic response transfer function is formed by synthesizing, and the formula is as follows:

[0034] ;

[0035] wherein, is the equivalent resistance coefficient, ; is the driving process dynamic response transfer function, is the Laplace complex variable;

[0036] The transfer function is arranged into a standard form as follows:

[0037] ;

[0038] wherein, the gain , the inertia coupling term , damping and stiffness coupling term , driving resistance and tire stiffness coupling term Therefore, the parameters related to the acceleration dynamic response include the vehicle mass, the equivalent resistance coefficient, the vehicle speed and the tire longitudinal slip stiffness.

[0039] In the further technical solution, in the step 3, the model is valued according to the parameters of the research object, and the parameters related to the acceleration dynamic response are respectively set as four groups of different values; the driving torque of different sinusoidal frequencies is applied under each group of parameters, the amplitude-frequency characteristic and the phase-frequency characteristic are recorded, and the Bode diagram is drawn; and the parameter most sensitive to the acceleration dynamic response is determined by analyzing the Bode diagram.

[0040] In the further technical solution, in the step 4, the extended Kalman filter is used to estimate the vehicle mass and the equivalent resistance coefficient, and the state vector is defined as: the motion state and the parameter to be estimated , wherein is the vehicle speed, is the acceleration;

[0041] The state equation is written as , wherein the input is the expected driving torque, and the expression of each component is as follows:

[0042] ;

[0043] The observation vector is defined as , and the observation equation is , wherein is the observation matrix;

[0044] The extended Kalman filter is used to estimate the vehicle mass and the equivalent resistance coefficient , and output to the feedforward control module;

[0045] The feedforward control module calculates the pre-compensation torque in real time according to the input expected acceleration, the vehicle mass and the equivalent resistance coefficient, and outputs, and the calculation formula is as follows:

[0046] ;

[0047] In the formula, is the vehicle mass estimation value, is the expected acceleration value, is the equivalent resistance estimation value, is the feedforward compensation torque;

[0048] The 2-DOF PID controller is used for closed-loop feedback adaptive control, and the output torque is:

[0049] ;

[0050] In the formula, is a closed-loop feedback adaptive control torque; is a proportional link coefficient, the value of which is calculated by multiplying an initial proportional link coefficient by the ratio of the estimated value of the overall vehicle mass to the initial value of the overall vehicle mass; is an integral link coefficient; is a differential link coefficient; is the Laplace transform of the expected acceleration; is the Laplace transform of the actual acceleration; is a differential filter cutoff frequency, is an integral weight coefficient, is a differential weight coefficient;

[0051] In the acceleration adaptive closed-loop control, the total control torque output is the superposition of the feedforward compensation torque and the closed-loop feedback adaptive control output torque, which acts on the overall vehicle to achieve closed-loop control of the acceleration, and the calculation formula is as follows:

[0052] ;

[0053] In the formula, is the total control torque.

[0054] The acceleration closed-loop control method for commercial vehicles considering load and running resistance provided by the embodiment of the application derives the dynamic response transfer function of the driving process by constructing a driving system dynamics model; after the key parameters most sensitive to the acceleration dynamic response are determined through analysis, the method of combining feedforward control and closed-loop feedback adaptive control is adopted to realize closed-loop adaptive control of the acceleration dynamic response. When the vehicle mass and the running resistance change, the method can effectively guarantee the consistency of the acceleration dynamic response, and thus improve the driving quality. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 is a general control architecture diagram of the acceleration closed-loop control method for commercial vehicles considering load and running resistance provided by the embodiment of the application;

[0056] Figure 2 is the influence of tire longitudinal slip stiffness on the acceleration response frequency characteristic;

[0057] Figure 3 is the influence of the overall vehicle mass on the acceleration response frequency characteristic;

[0058] Figure 4 is the influence of the equivalent resistance coefficient on the acceleration response frequency characteristic;

[0059] Figure 5 Influence of speed on acceleration response frequency characteristics;

[0060] Figure 6 Acceleration closed-loop adaptive control effect diagram. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0062] The specific implementation of the present application is described in detail below in combination with specific examples.

[0063] As shown in the figure, a commercial vehicle acceleration closed-loop control method considering load and driving resistance provided by an embodiment of the present application includes the following steps: Figure 1

[0064] Step 1: Dynamic modeling of the drive system;

[0065] The power transmission system model, wheel rotation dynamics model, tire model and longitudinal dynamics model are established according to the overall vehicle configuration. Among them, the power transmission system model is:

[0066] ;

[0067] In the formula, is the actual torque, is the required torque, is the torque response time constant, is the time.

[0068] The drive torque at the wheel is:

[0069] ;

[0070] In the formula, is the total transmission ratio, is the total transmission efficiency, is the torque applied to the wheel by the power system.

[0071] The wheel rotation dynamics model is:

[0072] ;

[0073] In the formula, is the equivalent moment of inertia of the power transmission system as a whole to the wheel end, is the wheel speed, is the wheel rolling radius, is the tire longitudinal force. ​

[0074] The tire model is:

[0075] ;

[0076] wherein, is the tire longitudinal slip stiffness, is the slip ratio.

[0077] The slip ratio is:

[0078] ;

[0079] wherein, is the driving speed.

[0080] The vehicle longitudinal dynamics model is:

[0081] ;

[0082] wherein, is the total vehicle mass, is the constant term of the resistance, is the resistance coefficient linearly related to the speed, is the resistance coefficient quadratically related to the speed.

[0083] Step 2: Modeling of the driving process dynamic response transfer function;

[0084] The Laplace transform is performed on the dynamics model of each subsystem and the longitudinal dynamics model of the whole vehicle to obtain the input and output transfer functions of each subsystem, and the transfer functions are integrated to form the driving process dynamic response transfer function of the whole vehicle.

[0085] Taking a pure electric commercial vehicle as the research object, the driving process dynamic response transfer function thereof is:

[0086] ;

[0087] wherein, is the equivalent resistance coefficient, ; is the driving process dynamic response transfer function, is the Laplace complex variable.

[0088] The transfer function is arranged into a standard form as follows:

[0089] ;

[0090] wherein, the gain , the inertia coupling term , the damping and stiffness coupling term , the driving resistance and tire stiffness coupling term Therefore, it is known that the parameters related to the acceleration dynamic response are the vehicle mass, the equivalent drag coefficient, the vehicle speed and the tire longitudinal slip stiffness.

[0091] Step 3: acceleration dynamic response control parameter determination;

[0092] The model is valued by taking a pure electric commercial vehicle as a research object, and the basic parameters of the vehicle are shown in Table 1.

[0093] Table 1 Basic parameters of the vehicle

[0094]

[0095] Further, the parameters related to the acceleration dynamic response are respectively set to four groups of different values, and different driving torques of different sine frequencies are applied to each group of values of each parameter, and the amplitude-frequency characteristics and phase-frequency characteristics are recorded and Bode diagrams are drawn, and the specific parameter value setting is shown in Table 2.

[0096] Table 2 Related parameter value setting

[0097]

[0098] The Bode diagrams of the tire longitudinal slip stiffness, the vehicle mass, the equivalent drag coefficient and the initial speed are shown in Table 2. Figures 2 to 5 As can be seen from the figure, the key parameters most sensitive to the acceleration dynamic response are the vehicle mass, the equivalent drag coefficient and the vehicle speed.

[0099] Step 4: acceleration adaptive closed-loop control;

[0100] The extended Kalman filter is used to estimate the vehicle mass and the equivalent drag coefficient, and the state vector is defined as: the motion state and the parameter to be estimated , wherein is the vehicle speed, is the acceleration.

[0101] The state equation is written as , wherein the input is the expected driving torque, and the expressions of each component are as follows:

[0102] ;

[0103] The observation vector is defined as , and the observation equation is , wherein is the observation matrix.

[0104] The extended Kalman filter is used to estimate the vehicle mass and the equivalent drag coefficient , and output to the feedforward control module.

[0105] The feedforward control module calculates and outputs a pre-compensation torque in real time according to inputted parameters such as expected acceleration, vehicle mass, equivalent resistance coefficient, etc., and the calculation formula is as follows:

[0106] ;

[0107] In the formula, is a vehicle mass estimation value, is an expected acceleration value, is an equivalent resistance estimation value, is a feedforward compensation torque.

[0108] A 2-DOF PID controller is used for closed-loop feedback adaptive control, and the output torque is:

[0109] ;

[0110] In the formula, is a closed-loop feedback adaptive control torque; is a proportional link coefficient, which is calculated by multiplying an initial proportional link coefficient by the ratio of the vehicle mass estimation value to the initial vehicle mass value; is an integral link coefficient; is a differential link coefficient; is a Laplace transform of the expected acceleration; is a Laplace transform of the actual acceleration; is a differential filter cutoff frequency, is an integral weight coefficient, is a differential weight coefficient.

[0111] In the acceleration adaptive closed-loop control, the total control torque output is the superposition of the feedforward compensation torque and the closed-loop feedback adaptive control output torque, which acts on the vehicle to realize closed-loop control of the acceleration, and the calculation formula is as follows:

[0112] ;

[0113] In the formula, is a total control torque.

[0114] As a preferred embodiment of the present application, according to the above four steps, taking a certain commercial vehicle as the research object, two different working conditions are selected to compare the control effect of the acceleration dynamic response consistency, working condition one is a vehicle mass of 8000 kg, an equivalent resistance coefficient of 50 Ns / m, and an initial vehicle speed of 20 m / s; working condition two is a vehicle mass of 24000 kg, an equivalent resistance coefficient of 300 Ns / m, and a vehicle speed of 20 m / s. It can be seen from Figure 6 that the present method has good control effect.

[0115] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A closed-loop acceleration control method for commercial vehicles considering load and driving resistance, characterized in that, Includes the following steps: Step 1: Drive system dynamics modeling; Based on the overall vehicle configuration, establish a powertrain system model, a wheel rotation dynamics model, a tire model, and a longitudinal dynamics model, and integrate the models of each subsystem to form a complete longitudinal dynamics model of the whole vehicle. Step 2: Modeling the dynamic response transfer function of the driving process; Laplace transforms are performed on the dynamic models of each subsystem and the longitudinal dynamic model of the whole vehicle to obtain the input and output transfer functions of each subsystem, and these are combined to form the dynamic response transfer function of the whole vehicle driving process; at the same time, the parameters related to the acceleration dynamic response are determined. Step 3: Determine the dynamic response control parameters for acceleration; By analyzing the amplitude-frequency and phase-frequency characteristics of parameters related to acceleration dynamic response, the key parameters most sensitive to acceleration dynamic response are identified. Step 4: Acceleration adaptive closed-loop control; The system integrates feedforward control with closed-loop feedback adaptive control. An extended Kalman filter is used for parameter estimation and provided to the feedforward control. The feedforward control calculates the pre-compensation torque based on real-time operating conditions. The closed-loop feedback adaptive control corrects the feedforward deviation and ensures the dynamic response of acceleration by adjusting the control parameters in real time and performing differential filtering.

2. The commercial vehicle acceleration closed-loop control method considering load and driving resistance according to claim 1, characterized in that, In step 1, a powertrain system model, a wheel rotational dynamics model, a tire model, and a longitudinal dynamics model are established based on the overall vehicle configuration; wherein, the powertrain system model is: ； In the formula, This is the actual torque. To meet the required torque, The torque response time constant, For time; The driving torque at the wheel is: ； In the formula, The total transmission ratio is... The total transmission efficiency. The torque applied to the wheels by the powertrain; The wheel rotation dynamics model is as follows: ； In the formula, This refers to the rotational inertia of the entire power transmission system, equivalent to the wheel ends. For wheel speed, The radius of the wheel's rolling motion. This refers to the longitudinal force of the tire; The tire model is as follows: ； In the formula, For tire longitudinal stiffness. Slip ratio; The slip ratio is: ； In the formula, The vehicle speed; The longitudinal dynamics model of the vehicle is as follows: ； In the formula, For the overall vehicle quality, For the resistance constant term, The drag coefficient is linearly related to speed. The drag coefficient is related to the square of the velocity.

3. The commercial vehicle acceleration closed-loop control method considering load and driving resistance according to claim 2, characterized in that, In step 2, the Laplace transform is performed on the dynamic models of each subsystem and the longitudinal dynamic model of the whole vehicle to obtain the input and output transfer functions of each subsystem. These are then combined to form the dynamic response transfer function of the whole vehicle driving process, as shown in the following formula: ； In the formula, This is the equivalent drag coefficient. ; The transfer function is used to drive the dynamic response of the process. For Laplace complex variables; The transfer function can be rearranged into its standard form as follows: ； Among them, gain Inertial coupling term Damping and stiffness coupling terms Driving resistance and tire stiffness coupling term The parameters related to the dynamic response of acceleration include vehicle mass, equivalent drag coefficient, vehicle speed, and tire longitudinal stiffness.

4. The commercial vehicle acceleration closed-loop control method considering load and driving resistance according to claim 3, characterized in that, In step 3, the model is assigned values ​​according to the parameters of the research object, and the acceleration dynamic response related parameters are set to four different sets of values. Under each set of parameters, a driving torque with a different sinusoidal frequency is applied, the amplitude frequency characteristics and phase frequency characteristics are recorded, and a Bode plot is drawn. By analyzing the Bode plot, the parameters most sensitive to the acceleration dynamic response are determined.

5. The commercial vehicle acceleration closed-loop control method considering load and driving resistance according to claim 4, characterized in that, In step 4, the vehicle mass and equivalent drag coefficient are estimated using an extended Kalman filter, and its state vector is defined as: motion state and parameters to be estimated. ,in, For vehicle speed, For acceleration; The state equation is written as , where, input The expressions for each component of the desired driving torque are as follows: ； Define the observation vector as The observation equation is ,in, The observation matrix; Using an extended Kalman filter to assess the overall vehicle mass With equivalent drag coefficient The estimation is performed and the result is output to the feedforward control module; The feedforward control module calculates and outputs the pre-compensation torque in real time based on the input desired acceleration, vehicle mass, and equivalent drag coefficient. The calculation formula is as follows: ； In the formula, This is an estimated value for the vehicle's total weight. The desired acceleration value, This is an estimate of the equivalent resistance. This is the feedforward compensation torque.

6. The commercial vehicle acceleration closed-loop control method considering load and driving resistance according to claim 5, characterized in that, In step 4, a 2-DOF PID controller is used for closed-loop feedback adaptive control, and the output torque is: ； In the formula, For closed-loop feedback adaptive control torque; This is the proportional coefficient, whose value is calculated by multiplying the initial proportional coefficient by the ratio of the estimated vehicle mass to the initial vehicle mass. The coefficients of the integral element; These are the coefficients of the differential element; The Laplace transform of the desired acceleration; The Laplace transform of the actual acceleration; This is the cutoff frequency of the differential filter. These are the integral weighting coefficients. These are the differential weighting coefficients; In acceleration adaptive closed-loop control, the total control torque output is the superposition of the feedforward compensation torque and the closed-loop feedback adaptive control output torque. This total control torque acts on the entire vehicle to achieve closed-loop acceleration control. Its calculation formula is as follows: ； In the formula, This is the total control torque.

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