CN111703417B - High-low speed unified pre-aiming sliding film driving control method and control system - Google Patents

Abstract

The invention belongs to the technical field of driving control, and discloses a high and low speed unified preview synovial driving control method and control system, a data acquisition module acquires vehicle driving road information; a model building module determines the vehicle road model and the vehicle dynamics model; The parameter acquisition module obtains the lateral position, lateral position change, lateral velocity and yaw rate related parameters of the vehicle train; the controller optimization module optimizes the sliding mode controller; the control module uses the optimized sliding film controller to perform driving control. According to the structural characteristics and kinematic requirements of the automobile train, the present invention proposes an automobile train driver model suitable for high and low speed modes. The low speed model can significantly improve the path followability of the trailer unit at low speed; Vehicle stability and safety, reducing yaw rate and lateral acceleration of each unit.

Description

A high and low speed unified preview synovial driving control method and control system

technical field

The invention belongs to the technical field of driving control, and in particular relates to a high and low speed unified preview synovial driving control method and control system.

Background technique

At present, the driving conditions of automobile trains are different from those of ordinary automobiles. Automobile trains have poorer path following performance at low speeds, worse lateral stability and more severe lateral movement of trailer units at high speeds, and The driver behavior of a single-unit vehicle is different from that of a single-unit vehicle, so the driver model of a single-unit vehicle cannot be simply applied to a multi-unit articulated trailer. At the same time, the driver's direction control model plays an important role in the simulation of the driver-car-road closed-loop system, the development of driver assistance systems, and the control of intelligent vehicles. Due to the limited research on the driver model of car trains, research and design are suitable for articulated The driver model of heavy vehicles is very necessary. The driver model of automobile trains can significantly improve the path following of automobile trains when cornering at low speeds and the lateral stability at high speeds. Handling stability and driving safety are of great significance.

Through the above analysis, the problems and defects of the existing technology are: the existing vehicle driving control model can only be applied to a single scene, and at the same time, the stability is not high, and the driving safety is not guaranteed.

Multi-Trailer Articulated Heavy Vehicle (MTAHV) has poor lateral stability when running at high speed, mainly manifested in dangerous working conditions such as trailer folding, trailer swinging and rollover. The articulation between adjacent vehicle units and the suspension of the tractor cab isolates the driver from the perception of the trailer's motion. It is difficult for the driver of a multi-trailer train to obtain the motion state of the trailer by feeling, and his perception of the motion of the train mainly comes from the tractor. When changing lanes on the expressway, the trailer often swings laterally, and this phenomenon may appear in the form of backward amplification. The yaw movement of the trailer has the characteristics of gradually amplifying from the tractor to the rear end in sequence, that is, compared with the tractor unit, the last trailer unit has the largest lateral acceleration. Therefore, the last trailer of the car train is often the first to have a rollover tendency and the possibility of rollover. This unique characteristic often causes rollover of articulated vehicles or car trains.

The "optimal preview closed-loop control" driver model proposed by scholars Reddy and Ellis uses this method to calculate the steering wheel angle and imitate the driver's control behavior. The error range cannot be too large, so the simulation results are very random. The single-point optimal control preview model proposed by MacAdam CC is flexible in actual use and can be put into practical application. However, once the vehicle speed changes too fast, the preview time cannot be fixed, resulting in a decrease in the accuracy of the preview distance. There are certain disadvantages. Guo Konghui proposed the "preview optimal curvature model" and the "prediction-following theory", but both are applicable to single-unit vehicles. Taking the yaw plane model of a five-axle semi-trailer vehicle train as the research object, Yang Xiaobo proposed a single-point preview driver model based on path preview, low-frequency and high-frequency compensation gain and time delay, and vehicle state prediction. Yang Hao, Huang Jiang et al. took road deviation and vehicle speed as input, and steering wheel angle as output to establish a fuzzy controller. According to the curvature of the road, two points far and near were selected to preview the driver model. This model establishes the far and near point preview model, but only uses the road curvature to select one point for preview.

The difficulty in solving the above problems and defects is as follows: due to the unique characteristics of the car train model, there are still technologies for establishing a multi-point preview driver model suitable for a double-trailer car train, including the preview information of the tractor and each trailer. defect.

The implication of addressing the above issues and shortcomings is that until now, people have focused their research on closed-loop directional dynamics of the driver/single-unit vehicle system. But little research has been done on the closed-loop directional dynamics of driver/articulated vehicle systems. Due to the large size and complex configuration of articulated semi-trailer commercial vehicles, compared with single-unit passenger vehicles, multi-unit articulated vehicles have unique directional dynamic characteristics, such as folding and trailer swing. In general, the driver behavior of an articulated car is different from that of a monocoque, they have worse path following performance at low speeds, and worse lateral stability and larger trailer units at high speeds Therefore, it is necessary to study and design a driver model suitable for articulated heavy vehicles, which is very necessary for lifting articulated vehicles The lateral stability of the train is of great significance.

The present invention combines predecessors' research and analysis on the approach rate of the synovium, and optimizes the design of the approach rate, which not only suppresses the shaking phenomenon when approaching the synovial surface to a certain extent, but also makes the approach speed increase with the distance from the synovial film. The distance of the surface has a certain adaptive function, which improves the control effect of the synovial film control to a certain extent. According to the structural characteristics and kinematic requirements of the automobile train, a multi-point preview driver model for the double-trailer automobile train is established, which includes the preview information of the tractor and each trailer, and is suitable for high and low speed modes. The low-speed model can improve the path followability of the trailer unit at low speed; the high-speed model can improve stability and reduce the yaw rate and lateral acceleration of each unit at high speed.

The technical route proposed by the present invention proposes new methods and new theories for the development of the multi-point preview driver model, in order to explore the feasibility and advantages and disadvantages of trailer preview, and to provide a basis for the design of trailer active steering control system, trailer differential braking, etc. The control system design and the control strategy and optimization design of the trailer active safety integrated control system have laid a theoretical foundation.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a high and low speed unified preview synovial driving control method and control system. Specifically relates to a high and low speed unified preview synovial film driving control method suitable for automobile trains.

The present invention is achieved in this way, a high and low speed unified preview synovial film driving system suitable for automobiles and trains, said high and low speed unified preview synovial film driving system suitable for automobiles and trains includes:

The data acquisition module is used to acquire the vehicle driving road information;

Model building blocks for determining vehicle road models as well as vehicle dynamics models;

The parameter acquisition module is used to obtain the lateral position, lateral position change, lateral velocity and yaw rate related parameters of the automobile train by using the dynamic model constructed and the state space equation of the automobile train;

The controller optimization module optimizes the slide film controller based on the lateral position, lateral position change, lateral velocity and yaw rate combined with driving road information;

The control module uses the optimized synovial film controller to calculate the front wheel angle, and uses the calculated front wheel angle as the state space and the control input of the controlled object for driving control.

Another object of the present invention is to provide a high and low speed unified preview synovial film driving control method suitable for automobiles and trains, which is applicable to the high and low speed unified preview synovial film driving system suitable for automobiles and trains. The high and low speed unified preview synovial film driving control method comprises:

Step 1, determining the vehicle road model and the vehicle dynamics model;

Step 2: Output the lateral position and lateral position change of the vehicle train from the dynamic model, obtain the lateral velocity and yaw rate from the state space equation of the vehicle train, based on the lateral position, lateral position change, lateral velocity and The yaw rate is combined with the road information to optimize the sliding film controller;

Step 3: Use the optimized synovial film controller to calculate the front wheel angle, and use the calculated front wheel angle as the state space and the control input of the controlled object for driving control.

Further, in step one, the vehicle road model and the vehicle dynamics model include:

The vehicle road model includes a vehicle high-speed road model or a low-speed road model;

The vehicle dynamics model is a Trucksim model or a linear model.

Further, in step 1, the high-speed road model or the low-speed road model includes:

The high-speed road model is a road preview model of the tractor, which is used to force the center of the front axle of the tractor to track the target trajectory by determining the steering angle of the front wheels of the tractor;

The low-speed road model is an expected path preview model, which is used to determine the front wheel rotation angle of the tractor according to the minimum lateral deviation of the tractor and the trailer.

Further, in step 2, the method for optimizing the sliding film controller includes: determining the sliding film surface and the reaching law of the sliding film controller based on the obtained road information, state space parameters and the linear or nonlinear model of the controlled object;

Specifically include:

1) Using the traditional synovial surface, the formula is

Where λ is the coefficient of the synovial film surface, and λ>0; S is the switching function; e is the error;

2) Using constant velocity reaching law, the expression is

Among them, the constant ε represents the rate at which the moving point of the system approaches the switching surface s=0.

Further, in step 3, the calculation formula of the front wheel rotation angle is:

Among them, e represents the comprehensive lateral position tracking deviation of vehicles and trains; Y(t+T _p ), Y(t+T _p -τ ₁ ), Y(t+T _p -τ _{2 )} respectively represent , t+T _p -τ ₁ , t+T _p -τ ₁ second-order state quantity; τ ₁ , τ ₂ represent time delay; t is time constant, T _p is preview time;

The formula for calculating the comprehensive lateral position tracking deviation e of the automobile and train is as follows:

e＝e ₁ +k ₁ e ₂ +k ₂ e ₃

In the formula, k ₁ and k ₂ are constants; e ₁ , e ₂ and e ₃ respectively represent the lateral position deviations of the center of mass of the front axle of the tractor, the center of mass of the first trailer and the center of mass of the second trailer, and the calculation formula is:

The second-order state quantities at the time t+T _p , t+T _p -τ ₁ , and t+T _p -τ ₂ are:

Among them, f(t) represents the corresponding position of the desired path at time T; Y(t) represents the coordinates on the desired path;

The time delay can be expressed as:

Another object of the present invention is to provide a sliding film controller for implementing the high and low speed unified preview sliding film driving control method. It is used to calculate the front wheel angle, and use the calculated front wheel angle as the state space and the control input of the controlled object for driving control.

Another object of the present invention is to provide an unmanned motor vehicle implementing the high and low speed unified preview synovial driving control method.

Another object of the present invention is to provide a computer device, the computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following step:

Determine the vehicle road model and vehicle dynamics model;

The lateral position and lateral position change of the vehicle train are output from the dynamic model, and the lateral velocity and yaw rate are obtained from the state space equation of the vehicle train, based on the lateral position, lateral position change, lateral velocity and yaw rate Combined with the driving road information to optimize the synovial film controller;

The optimized sliding film controller is used to calculate the front wheel angle, and the calculated front wheel angle is used as the state space and the control input of the controlled object for driving control.

Another object of the present invention is to provide a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the processor performs the following steps:

Determine the vehicle road model and vehicle dynamics model;

The lateral position and lateral position change of the vehicle train are output from the dynamic model, and the lateral velocity and yaw rate are obtained from the state space equation of the vehicle train, based on the lateral position, lateral position change, lateral velocity and yaw rate Combined with the driving road information to optimize the synovial film controller;

The optimized sliding film controller is used to calculate the front wheel angle, and the calculated front wheel angle is used as the state space and the control input of the controlled object for driving control.

Combining all the above-mentioned technical solutions, the advantages and positive effects of the present invention are as follows: the present invention proposes a high and low speed unified preview synovial film driver model suitable for automobiles and trains. A preview driver model is designed based on synovial film control technology, which can be applied not only to single-unit vehicles, but also to multi-unit vehicles.

The present invention is based on synovial film control and is suitable for a unified preview preview driver model of automobiles and trains. The model is suitable for both high-speed and low-speed working conditions. Control theory, determine the front wheel steering angle of the tractor, force the center of the front axle of the tractor to track the target trajectory; low speed is the expected path preview model, based on the traditional lateral preview control theory, the minimum lateral deviation of the tractor and the trailer determines the tractor The front wheel angles, thereby improving the vehicle's path following performance. The high-speed model of the invention mainly improves the stability and reduces the yaw angular velocity and lateral acceleration of the vehicle, and the low-speed model mainly improves the path following performance of the vehicle.

According to the structural characteristics and kinematic requirements of the automobile train, the present invention proposes an automobile train driver model suitable for high and low speed modes. The low speed model can significantly improve the path followability of the trailer unit at low speed; Vehicle stability and safety, reducing yaw rate and lateral acceleration of each unit.

Contrasting technical effects or experimental effects.

Taking the established linear four-degree-of-freedom yaw plane model as the control object, and using the high and low speed driver models established based on synovial film control as the controller, a multi-point preview driver model suitable for four-axis dual trailers is established. Firstly, the control effect of the driver model based on the constant speed approach rate and the optimized approach rate is compared and verified, and then the control effect of the high-speed and low-speed preview driver models is compared under high-low speed single-lane-changing conditions. Finally, the high-speed model The control effects of the TO model, the low-speed model and the TO model were compared and analyzed under high-speed and low-speed single-lane-shifting conditions, respectively.

(1) Based on the comparison and verification of the control effects of the constant speed approach rate and the optimized approach rate driver model, the results show that: compared with the constant speed approach rate, the optimized approach rate can effectively eliminate the vibration of the front wheel angle, Improve the lateral stability of the vehicle, and the high-speed control effect is obvious. The comparison results of high-speed and low-speed simulation are shown in Fig. 5 and Fig. 6 respectively.

(2) Comparing the control effect of the high-speed and low-speed preview driver models under high-low speed single-lane-changing conditions, the results show that, compared with the low-speed model, the high-speed model has a smaller steering effect under the 80km/h single-lane-changing condition. Under the force demand, it can effectively improve the lateral stability of the automobile train, reduce the yaw rate and the peak value of the lateral acceleration, and at the same time make the yaw rate of each trailer unit lower than that of the tractor; compared with the high-speed model, the low-speed model is in Under the 30km/h single-lane-changing condition, better path following can be achieved, but the stability and the peak value of the front wheel angle are relatively large.

Low speed mainly examines the path followability of automobile trains, and high speed mainly inspects the lateral stability of automobile trains. Therefore, under the condition of 30km/h low-speed single-track shifting, the control effect of the established low-speed driver model is better than that of high-speed driving. The control effect of this model is the best when it is used at low speed; under the high-speed single-lane-changing condition of 80km/h, the control effect of the established high-speed driver model is better than that of the low-speed driver model, and this model is used for medium and high speeds. When , the control effect is the best. As shown in Figure 7 and 8.

(3) The control effects of high-speed model and TO model (tractor single preview model), low-speed model and TO model were compared and analyzed under high-speed and low-speed single-lane-changing conditions, respectively. Compared with the high-speed TO model, the average peak values of lateral acceleration and yaw rate are increased by about 8% and 15%, respectively, and the integral of front wheel angle to time is reduced by about 6.19% under the condition that the path following performance is not much different; Compared with the low-speed TO model, the path followability of the tractor is not greatly improved in the low-speed model, but the followability of each trailer unit is obviously improved due to the introduction of deviation control. The average peak lateral acceleration and yaw rate of each unit of the car train are reduced by about 8% and 15% respectively. It can be found that the driver model of the car train based on the synovial film control is helpful to Improve the stability of the car train with less steering force. As shown in Figure 9 and 10.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the accompanying drawings required in the embodiments of the present application. Obviously, the accompanying drawings described below are only some embodiments of the present application. Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is a schematic structural diagram of a high and low speed unified preview synovial film driving control system suitable for automobile trains provided by an embodiment of the present invention;

In the figure: 1. Data acquisition module; 2. Model building module; 3. Parameter acquisition module; 4. Controller optimization module; 5. Control module.

Fig. 2 is a flow chart of a high and low speed unified preview synovial film driving control method suitable for automobiles and trains provided by an embodiment of the present invention.

Fig. 3 is a schematic diagram of a high and low speed unified preview synovial film driving control method suitable for automobiles and trains provided by an embodiment of the present invention.

Fig. 4 is a schematic diagram of a geometric representation of a car train model and an expected path provided by an embodiment of the present invention.

FIG. 5a)-FIG. 5f) are diagrams of high-speed simulation comparison results provided by the embodiment of the present invention.

FIG. 6a)-FIG. 6f) are low-speed simulation comparison results diagrams provided by the embodiment of the present invention.

Fig. 7a) - Fig. 7f) are the result comparison diagram group 1 of the high-speed condition provided by the embodiment of the present invention.

Fig. 8a) - Fig. 8f) are the result comparison diagram group 1 of the low-speed condition provided by the embodiment of the present invention.

Fig. 9a) - Fig. 9f) are the result comparison chart group 2 under the high-speed working condition provided by the embodiment of the present invention.

Fig. 10a) - Fig. 10d) are the result comparison diagram group 2 under the low-speed working condition provided by the embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Aiming at the problems existing in the prior art, the present invention provides a high and low speed unified preview synovial driving control method and control system. The present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, a high and low speed unified preview synovial film driving control system provided by an embodiment of the present invention includes:

The data acquisition module 1 is used to acquire the road information of the vehicle;

Model building block 2, used to determine the vehicle road model and the vehicle dynamics model;

The parameter acquisition module 3 is used to obtain the lateral position, lateral position change, lateral velocity and yaw rate related parameters of the automobile train by using the dynamic model constructed and the state space equation of the automobile train;

Controller optimization module 4, based on lateral position, lateral position change, lateral velocity and yaw rate combined with driving road information to optimize the slide film controller;

The control module 5 uses the optimized synovial film controller to calculate the front wheel rotation angle, and uses the calculated front wheel rotation angle as the state space and the control input of the controlled object to perform driving control.

As shown in Figures 2-3, the high and low speed unified preview synovial driving control method provided by the embodiment of the present invention includes:

S101, determining a vehicle road model and a vehicle dynamics model;

S102, output the lateral position and lateral position change of the vehicle train from the dynamic model, and obtain the lateral velocity and yaw rate from the state space equation of the vehicle train, based on the lateral position, lateral position change, lateral velocity and lateral The sliding film controller is optimized by combining the swing angular velocity with the driving road information;

S103, using the optimized synovial film controller to calculate the front wheel rotation angle, and use the calculated front wheel rotation angle as a state space and a control input of the controlled object to perform driving control.

In step S101, the vehicle road model and the vehicle dynamics model provided by the embodiment of the present invention include:

The vehicle road model includes a vehicle high-speed road model or a low-speed road model;

The vehicle dynamics model is a Trucksim model or a linear model.

In step S101, the high-speed road model or the low-speed road model provided by the embodiment of the present invention includes:

The high-speed road model is a road preview model of the tractor, which is used to force the center of the front axle of the tractor to track the target trajectory by determining the steering angle of the front wheels of the tractor;

The low-speed road model is an expected path preview model, which is used to determine the front wheel rotation angle of the tractor according to the minimum lateral deviation of the tractor and the trailer.

In step S102, the method for optimizing the sliding film controller provided by the embodiment of the present invention includes: determining the sliding film surface and the reaching law of the sliding film controller based on the obtained road information, state space parameters and the linear or nonlinear model of the controlled object ;

Specifically include:

1) Using the traditional synovial surface, the formula is

Where λ is the coefficient of the synovial film surface, and λ>0; S is the switching function; e is the error;

2) Using constant velocity reaching law, the expression is

Among them, the constant ε represents the rate at which the moving point of the system approaches the switching surface s=0.

In step S103, the calculation formula of the front wheel rotation angle provided by the embodiment of the present invention is:

Among them, e represents the comprehensive lateral position tracking deviation of vehicles and trains; Y(t+T _p ), Y(t+T _p -τ ₁ ), Y(t+T _p -τ _{2 )} respectively represent , t+T _p -τ ₁ , t+T _p -τ ₁ second-order state quantity; τ ₁ , τ ₂ represent time delay; t is time constant, T _p is preview time;

The formula for calculating the comprehensive lateral position tracking deviation e of the automobile and train is as follows:

e＝e ₁ +k ₁ e ₂ +k ₂ e ₃

In the formula, k ₁ and k ₂ are constants; e ₁ , e ₂ and e ₃ respectively represent the lateral position deviations of the center of mass of the front axle of the tractor, the center of mass of the first trailer and the center of mass of the second trailer, and the calculation formula is:

The second-order state quantities at the time t+T _p , t+T _p -τ ₁ , and t+T _p -τ ₂ are:

Among them, f(t) represents the corresponding position of the desired path at time T; Y(t) represents the coordinates on the desired path;

The time delay can be expressed as:

The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

Example:

A high and low-speed unified preview synovial film driver model suitable for automobile trains, including the setting of the vehicle driving road, the design of the variable structure controller of the synaptic film, the establishment of the vehicle dynamics model and the acquisition of vehicle parameters. The driving roads are the high-speed road model and the low-speed road model, and the high-speed road is the tractor road preview model. In the high-speed tractor road preview model, based on the traditional lateral position preview control theory, the front wheel steering angle of the tractor is determined. Force the center of the front axle of the tractor to track the target trajectory, and the position of the center of mass of the trailer unit to track the path passed by the center of the front axle of the tractor, that is, the expected path tracked by the trailer unit is the path of the center of mass of the front axle of the tractor after a specific time delay, and the low speed is the desired Path preview model. In the low-speed tractor road preview model, in the process of the vehicle following the desired path, based on the traditional lateral preview control theory, the front wheel angle of the tractor is determined by the minimum lateral deviation of the tractor and the trailer, and the expectations of the tractor and the trailer The path is the corresponding value of the actual path at a specific time. Its vehicle dynamics model is a Trucksim model or a linear model. In addition, the controller of this model adopts the synovial film variable structure control with strong robustness and anti-interference ability. The controller is designed based on the reaching law, and the corresponding output values of the road information, state space parameters and the linear or nonlinear model of the controlled object are used as the control input of the sliding film controller, and finally an ideal reaching law and sliding film controller are obtained. controller. The sliding membrane surface of the sliding membrane variable structure controller adopts the traditional sliding membrane surface, and its formula is Where λ is the coefficient of the synovial film surface, and λ>0; S is the switching function; e is the error, in order to make the combined tracking error e and its derivative /> Converge quickly, make the synovial surface S be zero, and thus obtain the synovial surface coefficient λ. The traditional synovial surface is more commonly used, and its design form is relatively simple, and at the same time it can achieve better control effect. In addition, in order to weaken the chattering phenomenon of the system, the sliding film controller adopts the constant speed reaching law, the expression is Among them, the constant ε represents the rate at which the moving point of the system approaches the switching surface s=0. If ε is small, the approach speed is slow; if ε is large, the moving point will have a greater speed when it reaches the switching surface, and the resulting jitter will be greater. The approach speed is fixed in the case of constant velocity approach law, which can effectively reduce the jitter phenomenon of the synovial film control. According to the trajectory of the car on the road, the desired trajectory determines the relationship between the X and Y coordinates on the vehicle trajectory. The coordinate Y(t) on the desired path is expressed as f(t), which means that the desired path is at time T The corresponding position of , select e ₂ and e ₃ to denote the lateral position deviation of the first trailer and the second trailer of the vehicle model respectively. Assuming that the front wheel steering angle is constant in the time period (t,t+T _p ), the output of the linear yaw plane model and the state variables can be predicted according to the time constant t of the state variables, where T _p is the preview time. At time t+T _p , t+T _p -τ ₁ and t+T _p -τ ₂ , the second-order state quantities are:

Among them, the time delay can be approximated as:

At this time, the lateral position deviations of the center of mass of the front axle of the tractor, the center of mass of the first trailer and the center of mass of the second trailer are respectively expressed as: e ₁ , e ₂ , e ₃ , which can be expressed as:

e ₁ ＝f(t+T _p )-Y ₁ (t+T _p )

e ₂ ＝f(t+T _p -τ ₁ )-Y ₂ (t+T _p )

e ₃ ＝f(t+T _p -τ ₂ )-Y ₃ (t+T _p )

Due to the relationship between the lateral position tracking deviation of the three-unit vehicle, the comprehensive lateral position tracking deviation of the vehicle train is:

e＝e ₁ +k ₁ e ₂ +k ₂ e ₃ where k ₁ and k ₂ are constants

Combined with the parameters of the state space, the steering angle formula is finally obtained as:

According to the structural characteristics and kinematic requirements of the automobile train, the present invention proposes an automobile train driver model suitable for high and low speed modes. The low speed model can significantly improve the path followability of the trailer unit at low speed; Vehicle stability and safety, reducing yaw rate and lateral acceleration of each unit.

The present invention will be further described below in conjunction with specific experiments and simulation effects.

Fig. 4 is a schematic diagram of a geometric representation of a car train model and an expected path provided by an embodiment of the present invention.

FIG. 5a)-FIG. 5f) are diagrams of high-speed simulation comparison results provided by the embodiment of the present invention.

FIG. 6a)-FIG. 6f) are low-speed simulation comparison results diagrams provided by the embodiment of the present invention.

Fig. 7a) - Fig. 7f) are the result comparison diagram group 1 of the high-speed condition provided by the embodiment of the present invention.

Fig. 8a) - Fig. 8f) are the result comparison diagram group 1 of the low-speed condition provided by the embodiment of the present invention.

Fig. 9a) - Fig. 9f) are the result comparison chart group 2 under the high-speed working condition provided by the embodiment of the present invention.

Fig. 10a) - Fig. 10d) are the result comparison diagram group 2 under the low-speed working condition provided by the embodiment of the present invention.

Among them, the established linear four-degree-of-freedom yaw plane model is used as the control object, and the high and low speed driver model based on the synovial film control is used as the controller to establish a multi-point preview driver model suitable for four-axis dual trailers. Firstly, the control effect of the driver model based on the constant speed approach rate and the optimized approach rate is compared and verified, and then the control effect of the high-speed and low-speed preview driver models is compared under high-low speed single-lane-changing conditions. Finally, the high-speed model The control effects of the TO model, the low-speed model and the TO model were compared and analyzed under high-speed and low-speed single-lane-shifting conditions, respectively.

(1) Based on the comparison and verification of the control effects of the constant speed approach rate and the optimized approach rate driver model, the results show that: compared with the constant speed approach rate, the optimized approach rate can effectively eliminate the vibration of the front wheel angle, Improve the lateral stability of the vehicle, and the high-speed control effect is obvious. The comparison results of high-speed and low-speed simulations are shown in Figure 5 and Figure 6 respectively:

Fig. 5a) Lateral position deviation for optimal approach rate control; Fig. 5b) Lateral position deviation for constant rate of approach control. Figure 5c) Comparison of yaw rate. Fig. 5d) Comparison of lateral acceleration. Figure 5e) Comparison of front wheel rotation angles. Figure 5f) Comparison of the lateral position deviation between the preview point and the expected point. Figure 6a) Lateral position deviation for optimized approach rate control, Figure 6b) Lateral position deviation for constant rate of approach control. Figure 6c) Comparison of yaw rate. Figure 6d) Comparison of lateral acceleration. Figure 6e) Comparison of front wheel rotation angles. Fig. 6f) Comparison of lateral position deviation.

(2) Comparing the control effect of the high-speed and low-speed preview driver models under high-low speed single-lane-changing conditions, the results show that, compared with the low-speed model, the high-speed model has a smaller steering effect under the 80km/h single-lane-changing condition. Under the force demand, it can effectively improve the lateral stability of the automobile train, reduce the yaw rate and the peak value of the lateral acceleration, and at the same time make the yaw rate of each trailer unit lower than that of the tractor; compared with the high-speed model, the low-speed model is in Under the 30km/h single-lane-changing condition, better path following can be achieved, but the stability and the peak value of the front wheel angle are relatively large.

Low speed mainly examines the path followability of automobile trains, and high speed mainly inspects the lateral stability of automobile trains. Therefore, under the condition of 30km/h low-speed single-track shifting, the control effect of the established low-speed driver model is better than that of high-speed driving. The control effect of this model is the best when it is used at low speed; under the high-speed single-lane-changing condition of 80km/h, the control effect of the established high-speed driver model is better than that of the low-speed driver model, and this model is used for medium and high speeds. When , the control effect is the best. Fig. 7a) Lateral position deviation of high-speed model; Fig. 7b) Lateral position deviation of low-speed model. Figure 7c) Comparison of yaw rate. Fig. 7d) Comparison of lateral acceleration. Figure 7e) Comparison of front wheel rotation angles. Fig. 7f) Comparison of lateral position deviation. Figure 8a) Low speed model lateral position deviation. Fig. 8b) High-speed model lateral position deviation. Figure 8c) Comparison of yaw rate. Fig. 8d) Comparison of lateral acceleration. Figure 8e) Comparison of front wheel rotation angles. Fig. 8f) Comparison of lateral position deviation.

(3) The control effects of high-speed model and TO model (tractor single preview model), low-speed model and TO model were compared and analyzed under high-speed and low-speed single-lane-changing conditions, respectively. Compared with the high-speed TO model, the average peak values of lateral acceleration and yaw rate are increased by about 8% and 15%, respectively, and the integral of front wheel angle to time is reduced by about 6.19% under the condition that the path following performance is not much different; Compared with the low-speed TO model, the path followability of the tractor is not greatly improved in the low-speed model, but the followability of each trailer unit is obviously improved due to the introduction of deviation control. The average peak lateral acceleration and yaw rate of each unit of the car train are reduced by about 8% and 15% respectively. It can be found that the driver model of the car train based on the synovial film control is helpful to Improve the stability of the car train with less steering force. Figure 9a) Comparison of tractor following performance. Fig. 9b) Comparison of followability of the first trailer. Figure 9c) Comparison of the followability of the second trailer. Fig. 9d) Comparison of yaw rate. Fig. 9e) Comparison of lateral acceleration. Figure 9f) Comparison of front wheel rotation angles. Figure 10a) Comparison of tractor followability. Fig. 10b) Comparison of followability of the first trailer. Figure 10c) Comparison of the followability of the second trailer. Figure 10d) Comparison of front wheel rotation angles.

In the description of the present invention, unless otherwise stated, the meaning of "plurality" is two or more; the terms "upper", "lower", "left", "right", "inner", "outer" , "front end", "rear end", "head", "tail", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Anyone familiar with the technical field within the technical scope disclosed in the present invention, whoever is within the spirit and principles of the present invention Any modifications, equivalent replacements and improvements made within shall fall within the protection scope of the present invention.

Claims (8)

1. The high-low speed unified pre-aiming sliding film driving control method is characterized by comprising the following steps of:

determining an automobile road model and an automobile dynamics model;

outputting the lateral position and the lateral position change of the automobile train by the determined automobile dynamics model;

obtaining lateral speed and yaw rate from a state space equation of the automobile train, and optimizing a synovial membrane controller based on the lateral position, the lateral position change, the lateral speed and the yaw rate combined with the determined driving road information in the automobile road model;

calculating to obtain a front wheel rotation angle by using an optimized sliding film controller, and taking the calculated front wheel rotation angle as a state space and a control input of a controlled object to carry out driving control;

the optimization method of the sliding film controller comprises the following steps: determining a synovial surface and an approach law of a synovial controller based on the acquired road information, state space parameters and a linear or nonlinear model of the controlled object;

the method specifically comprises the following steps:

1) Adopts the traditional sliding film surface, and the formula is

Wherein lambda is the synovial face coefficient, and lambda > 0; s is a switching function; e is error;

2) Adopts a constant velocity approach law, and the expression is

Wherein the constant epsilon represents the rate at which the system's motion point approaches the switching plane s=0;

the front wheel steering angle calculation formula is as follows:

wherein e represents the comprehensive lateral position tracking deviation of the automobile train; τ ₁ 、τ ₂ Representing a time delay; t is a time constant, T _p Is the pre-aiming time; y is Y ₁ 、Y ₂ 、Y ₃ The lateral positions of the mass centers of the tractor, the first trailer and the second trailer are respectively;representing the front axle centroid of the tractor, the time lag of the front axle centroid of the tractor for the first trailer centroid and the time lag lateral acceleration of the front axle centroid of the tractor for the second trailer centroid, respectively;

the comprehensive lateral position tracking deviation e of the automobile train has the following calculation formula:

e＝e ₁ +k ₁ e ₂ +k ₂ e ₃ ；

wherein k is ₁ 、k ₂ Is a constant; e, e ₁ 、e ₂ 、e ₃ The lateral position deviation of the front axle center of the tractor, the center of mass of the first trailer and the center of mass of the second trailer are respectively represented, and the calculation formula is as follows:

the time t+T _p 、t+T _p -τ ₁ 、t+T _p -τ ₂ The second-order state quantity is:

wherein f (T) represents the corresponding position of the desired path at time T; y (T) represents coordinates on the desired path, Y (t+T) _p )、Y(t+T _p -τ ₁ )、Y(t+T _p -τ ₂ ) Respectively at time t+T _p 、t+T _p -τ ₁ 、t+T _p -τ ₂ A second order state quantity at that time.

2. The high-low speed unified pre-aiming synovial membrane driving control method as claimed in claim 1, characterized in that,

the automobile road model comprises an automobile expressway model or a low-speed road model;

the automobile dynamics model is a Trucksim model or a linear model.

3. The high-low speed unified pre-aiming synovial membrane driving control method according to claim 2, wherein said expressway model or said low-speed road model comprises:

the expressway model is a tractor road pre-aiming model and is used for enabling the center of a front axle of the tractor to track a target track by determining the steering angle of front wheels of the tractor;

the low-speed road model is a desired path pre-aiming model and is used for determining the front wheel corner of the tractor through the minimum lateral deviation of the tractor and the trailer.

4. The high-low speed unified pre-aiming sliding film driving control system is characterized in that the high-low speed unified pre-aiming sliding film driving control system is used for an automobile train and used for executing the high-low speed unified pre-aiming sliding film driving control method according to any one of claims 1-3, and specifically comprises the following steps:

the data acquisition module is used for acquiring the information of the automobile driving road;

the model building module is used for determining an automobile road model and an automobile dynamics model;

the parameter acquisition module is used for obtaining the lateral position, lateral position change, lateral speed and yaw rate related parameters of the automobile train by utilizing the constructed dynamics model and a state space equation of the automobile train;

the controller optimization module is used for optimizing the sliding film controller based on the lateral position, the lateral position change, the lateral speed and the yaw rate in combination with the driving road information;

and the control module is used for calculating the front wheel rotation angle by using the optimized synovial membrane controller, and carrying out driving control by taking the calculated front wheel rotation angle as a state space and the control input of a controlled object.

5. A synovial membrane controller for implementing the high-low speed unified pre-aiming synovial membrane driving control method according to any one of claims 1-3, which is used for calculating the front wheel rotation angle, and using the calculated front wheel rotation angle as the control input of the state space and the controlled object to carry out driving control.

6. An unmanned motor vehicle implementing the high-low speed unified pre-aiming synovial membrane driving control method according to any one of claims 1 to 3.

7. A computer device comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the high-low speed unified pre-aiming slide film driving control method as claimed in any one of claims 1 to 3.

8. A computer-readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the high-low speed unified pre-aiming synovial driving control method as claimed in any one of claims 1 to 3.