阅读说明：本技术 一种巡航模式下商用车前瞻换挡控制方法 (Method for controlling prospective gear shifting of commercial vehicle in cruise mode ) 是由 付尧 雷雨龙 李兴忠 王林波 于 2019-11-07 设计创作，主要内容包括：本发明公开一种巡航模式下商用车前瞻换挡控制方法包括步骤1：获取车辆当前行驶位置、坡道信息,并根据行驶目的地获取车辆未来一段行驶路径中的道路坡道信息,将其按距离长度h离散为N段；步骤2：从初始状态和/或结束状态方向上进行动态规划,并获取最优换挡控制序列；步骤3：结合车辆初始状态及所述最优换挡控制序列,确定车辆最优状态轨迹,得到循环工况下最佳换挡点。本发明设计开发的巡航模式下商用车前瞻换挡控制方法,能够根据车辆预计行驶路段的坡道信息,以总油耗和总行驶时间作为综合性能指标优化获得预计行驶路段的最优换挡控制序列,并确定车辆最优状态轨迹。(The invention discloses a method for controlling the forward looking gear shifting of a commercial vehicle in a cruise mode, which comprises the following steps of 1: acquiring the current driving position and the ramp information of the vehicle, acquiring road ramp information in a future section of driving path of the vehicle according to a driving destination, and dispersing the road ramp information into N sections according to the distance length h; step 2: performing dynamic planning from the direction of the initial state and/or the end state, and acquiring an optimal gear shifting control sequence; and step 3: and determining the optimal state track of the vehicle by combining the initial state of the vehicle and the optimal gear shifting control sequence to obtain the optimal gear shifting point under the circulating working condition. The commercial vehicle forward-looking gear-shifting control method under the cruise mode can optimize and obtain the optimal gear-shifting control sequence of the predicted running road section by taking the total oil consumption and the total running time as comprehensive performance indexes according to the ramp information of the predicted running road section of the vehicle, and determine the optimal state track of the vehicle.)

1. A method for controlling the forward looking gear shifting of a commercial vehicle in a cruise mode is characterized by comprising the following steps:

step 1: acquiring the current driving position and the ramp information of the vehicle, acquiring the road ramp information in the driving path of the vehicle according to the driving destination, and dispersing the road ramp information into N sections according to the distance length h;

step 2: dynamically planning from the initial state and/or end state direction and obtaining an optimal shift control sequence, comprising:

starting from the initial stage 0 and/or the end stage N, acquiring index function values of each corresponding stage according to all possible states of the vehicle and gear-shifting control instructions in the stage, and determining the optimal gear and the corresponding gear-shifting control instruction in the stage;

sequentially increasing and/or decreasing, acquiring corresponding stage index functions when different control instructions are carried out according to the vehicle states of all stages meeting the state transition relation, respectively accumulating the current stage and all acquired stage index function values according to the state transition relation to obtain a process index function, and determining an optimal gear shifting instruction;

determining an optimal gear shifting control sequence until the end stage N and/or the initial stage 0;

wherein the stage index function is:

and/or

Process index function J_kComprises the following steps:

J_k＝J_k-1+Δm_f(x (k), u (k)); and/or

J_k＝J_k+1+Δm_f(x(k),u(k))；

Wherein the content of the first and second substances,is the instantaneous fuel consumption of the engine, v is the vehicle speed, J_kIs the process index function at phase k, Δ m_f(x (k), u (k)) is a phase index function for phase k, α is a weight for travel time in process, β is a weight for fuel consumption in process, d_sIs the discrete length of the segment, x (k) is the vehicle state, u (k) is the shift control command;

and step 3: and determining the optimal state track of the vehicle by combining the initial state of the vehicle and the optimal gear shifting control sequence to obtain the optimal gear shifting point under the circulating working condition.

2. The method for controlling the commercial vehicle look-ahead gear shift in the cruise mode according to claim 1, characterized by further comprising the steps of planning the vehicle speed globally between the step 2 and the step 1, and obtaining a global optimal speed track by adopting a discrete planning.

3. The cruise mode commercial vehicle look-ahead shift control method according to claim 2, characterized in that the vehicle conditions are:

x(k)＝[g(k),v(k)]^T；

wherein, 1 is less than or equal to g (k) is less than or equal to 12;

0≤v(k)≤v_sikmax；

g (k) is gear; v (k) is vehicle speed; u (k) is a shift command, with 0 representing no shift, 1 representing an upshift, and-1 representing a downshift;

4. A method for commercial vehicle look-ahead gear change control in cruise mode according to claim 2 or 3, characterized in that the vehicle speed is:

wherein, T_eAs engine torque, i_gFor the current gear ratio, i₀At a final reduction ratio of η_TFor the transmission efficiency of the whole system, m is the mass of the automobile, g is the gravity acceleration, f is the rolling resistance coefficient, i is the ramp coefficient, C_DIs the windward resistance coefficient, A is the windward area, rho is the air density, r is the rolling radius of the wheel, J_wIs the moment of inertia of the wheel, J_eIs the rotational inertia of the engine.

5. The cruise mode commercial vehicle look-ahead shift control method according to claim 4, wherein said engine torque is:

wherein a is the opening degree of an accelerator; k is a radical of_(p,q)Is a coefficient; omega_eIs the engine speed.

6. The method for controlling the commercial vehicle forward-looking shift in cruise mode according to claim 1, 2, 3 or 5, characterized in that the instantaneous specific fuel consumption of said engine is:

wherein, P_eα is the instantaneous power of the engine₁、α₂、α₃Is a coefficient.

7. The cruise mode prospective shift control method for a commercial vehicle according to claim 1, 2, 3 or 5, characterized in that in step 2, dynamic planning is performed in both directions from an initial state and an end state, and an optimal shift control sequence is obtained.

8. The cruise mode commercial vehicle look-ahead shift control method according to claim 7, wherein in step 3, the vehicle optimum state trajectory is determined using a sequential recursion method.

9. The method for controlling the look-ahead gear shifting of the commercial vehicle in the cruise mode according to claim 8, wherein according to the optimal gear shifting control sequence and the initial state of the vehicle, the vehicle speed and the throttle opening information corresponding to the corresponding gear shifting moment are sequentially determined in a recursion mode, and the optimal gear shifting sequence corresponding to the whole cycle working condition is obtained.

Technical Field

The invention relates to the technical field of gear shifting control, in particular to a method for controlling the forward looking gear shifting of a commercial vehicle in a cruise mode.

Background

Commercial vehicles play an important role in the economic construction industry of China and are an important component of highway traffic. Because of the large load, the fuel consumption is several times of that of a passenger car, and in terms of use cost, the fuel consumption cost approximately accounts for 1/3 of cost expenditure in a use period. Therefore, the reduction of fuel consumption has practical significance for realizing the aims of energy conservation and emission reduction and reducing the transportation cost. The automatic transmission can automatically switch gears according to the requirements of human-vehicle-road environment, adjust the operating condition point of an engine, efficiently and stably transmit power, is a key assembly for realizing energy conservation of automobiles, and is widely applied to the field of commercial vehicles.

Commercial vehicles mainly used for long-distance transportation mostly run on high-speed road conditions, a driver operates the vehicles to cruise at a certain speed within a regulation speed limit range, and the vehicles provided with cruise control devices can automatically control an accelerator and brake under the setting operation of the driver so as to realize speed control. For commercial vehicles, the proportion of the cruising driving state to the driving state of the vehicle is high, and the improvement of the fuel economy in the state is particularly important for realizing the economic transportation target. In cruise mode, the change of the automatic transmission gear is still based on the shift schedule MAP. As an important factor influencing the economic level of the whole vehicle, a gear-shifting control strategy (gear decision) undergoes transition from single parameter (vehicle speed or throttle opening), two parameters (vehicle speed and throttle opening) and three dynamic parameters (vehicle speed, throttle opening and acceleration) to intellectualization. The intelligent gear decision is to modify the gear shifting points through driving environment identification, driver intention identification and vehicle state parameter identification on the basis of a two-parameter or three-parameter gear shifting rule, and can take a human-vehicle-road system as a whole to realize gear shifting which meets the driver power requirement and the current driving environment and gives consideration to the vehicle state.

Although the control performance of the transmission is improved to a certain extent by an intelligent gear-shifting control strategy, the intelligent gear-shifting control strategy has a certain gap compared with an empirical driver under certain special driving conditions or states, one important reason is that the system does not have the ability of looking ahead at disturbance factors such as roads and traffic conditions and making decisions based on knowledge, and the adaptability of gear-shifting to future short-time driving environment changes cannot be guaranteed only by taking current driving environment information as gear decision input. With the wide application of a Global Positioning System (GPS) and a Geographic Information System (GIS) in the automobile field and the development of an ITS (Internet technology integration) and intelligent networked automobile environment sensing technology, more accurate driving environment and traffic information can be provided for a power assembly comprising a transmission, so that gear decision based on prospective road information becomes possible.

Road grade changes are main factors influencing fuel economy of the commercial vehicle in a cruising state, experienced drivers often actively adjust gears and vehicle speed based on predictive grade information, and kinetic energy consumption caused by low-efficiency operation and braking of an engine is avoided.

Disclosure of Invention

The invention designs and develops a commercial vehicle forward looking gear shifting control method in a cruise mode, which can optimize and obtain an optimal gear shifting control sequence of a predicted driving road section by taking total oil consumption and total driving time as comprehensive performance indexes according to ramp information of the predicted driving road section of a vehicle, and determine an optimal state track of the vehicle.

The technical scheme provided by the invention is as follows:

a method for controlling the forward looking gear shifting of a commercial vehicle in a cruise mode comprises the following steps:

step 1: acquiring the current driving position and the ramp information of the vehicle, acquiring the road ramp information in the driving path of the vehicle according to the driving destination, and dispersing the road ramp information into N sections according to the distance length h;

step 2: dynamically planning from the initial state and/or end state direction and obtaining an optimal shift control sequence, comprising:

starting from the initial stage 0 and/or the end stage N, acquiring index function values of each corresponding stage according to all possible states of the vehicle and gear-shifting control instructions in the stage, and determining the optimal gear and the corresponding gear-shifting control instruction in the stage;

sequentially increasing and/or decreasing, acquiring corresponding stage index function values when different control instructions are carried out according to the vehicle states of all stages meeting the state transition relation, respectively accumulating the current stage and all the obtained stage index function values according to the state transition relation to obtain process index function values, and determining an optimal gear shifting instruction;

determining an optimal gear shifting control sequence until the end stage N and/or the initial stage 0;

wherein the stage index function is:

and/or

Process index function J_kComprises the following steps:

J_k＝J_k-1+Δm_f(x (k), u (k)); and/or

J_k＝J_k+1+Δm_f(x(k),u(k))；

Wherein the content of the first and second substances,is the instantaneous fuel consumption of the engine, v is the vehicle speed, J_kIs the process index function at phase k, Δ m_f(x (k), u (k)) is a phase index function for phase k, α is a weight for travel time in process, β is a weight for fuel consumption in process, d_sIs the discrete length of the segment, x (k) is the vehicle state, u (k) is the shift control command;

and step 3: and determining the optimal state track of the vehicle by combining the initial state of the vehicle and the optimal gear shifting control sequence to obtain the optimal gear shifting point under the circulating working condition.

Preferably, between step 2 and step 1, vehicle speed planning is performed on the whole, and a global optimal speed trajectory is obtained by adopting discrete planning.

Preferably, the vehicle state is:

x(k)＝[g(k),v(k)]^T；

wherein, 1 is less than or equal to g (k) is less than or equal to 12;

0≤v(k)≤v_sikmax；

g (k) is gear; v (k) is vehicle speed; u (k) is a shift command, with 0 representing no shift, 1 representing an upshift, and-1 representing a downshift;

for vehicle start and end state constraints, v_sikmaxIs the maximum value in the vehicle speed trajectory for stage k in the optimal speed trajectory.

Preferably, the vehicle speed is:

wherein, T_eAs engine torque, i_gFor the current gear ratio, i₀At a final reduction ratio of η_TFor the transmission efficiency of the whole system, m is the mass of the automobile, g is the gravity acceleration, f is the rolling resistance coefficient, i is the ramp coefficient, C_DIs the windward resistance coefficient, A is the windward area, rho is the air density, r is the rolling radius of the wheel, J_wIs the moment of inertia of the wheel, J_eIs the rotational inertia of the engine.

Preferably, the engine torque is:

wherein a is the opening degree of an accelerator; k is a radical of_(p,q)Is a coefficient; omega_eIs the engine speed.

Preferably, the instantaneous specific fuel consumption of the engine is:

wherein, P_eα is the instantaneous power of the engine₁、α₂、α₃Is a coefficient.

Preferably, in step 2, the dynamic programming is performed in both directions from the initial state and the end state, and the optimal shift control sequence is obtained.

Preferably, in step 3, the optimal state trajectory of the vehicle is determined by a sequential recursion method.

Preferably, according to the optimal gear shifting control sequence and the initial state of the vehicle, sequentially recurrently determining the vehicle speed and the throttle opening information corresponding to the corresponding gear shifting moment, and obtaining the optimal gear shifting sequence corresponding to the whole cycle working condition.

The invention has the following beneficial effects:

the commercial vehicle forward-looking gear-shifting control method under the cruise mode can optimize and obtain the optimal gear-shifting control sequence of the predicted running road section by taking the total oil consumption and the total running time as comprehensive performance indexes according to the ramp information of the predicted running road section of the vehicle, and determine the optimal state track of the vehicle.

Drawings

FIG. 1 is a flow chart of a commercial vehicle look-ahead gear shift control method in a cruise mode.

FIG. 2 is a schematic diagram of a hierarchical look-ahead shift controller according to an embodiment of the present invention.

Fig. 3 is a flowchart of the global vehicle speed planning according to the embodiment of the present invention.

Fig. 4 is a flowchart of optimizing a target gear by the dynamic programming algorithm according to the embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating the effect of the ramp on the gear according to the embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating the effect of a hill on vehicle speed according to an embodiment of the present invention.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

As shown in FIG. 1, the invention provides a method for controlling the forward looking gear shifting of a commercial vehicle in a cruise mode, which comprises the following steps:

step 1: vehicle analytic modeling

The analytical modeling of the vehicle mainly comprises an engine oil consumption model and a longitudinal dynamic model of the whole vehicle, wherein the engine oil consumption model is a static oil consumption model, a quadratic polynomial with engine power as a parameter is used for fitting the instantaneous oil consumption of the engine and can be expressed in a form of a formula (1),

in the formula (I), the compound is shown in the specification,

is the instantaneous fuel consumption rate of the engine; p_eα is the instantaneous power of the engine₁、α₂、α₃The fitting coefficient is obtained by fitting the universal characteristic curve of the engine by adopting a least square method.

The fitting relation of the engine torque, the accelerator opening and the engine speed can be obtained by fitting the torque demand of the driver as shown in formula (2), the corresponding relation of the vehicle speed and the engine speed can be obtained by considering the speed ratio of the corresponding gear, and finally the mapping relation of the instantaneous fuel consumption of the engine, the accelerator opening and the engine speed is obtained.

Wherein, T_eIs the engine torque, a is the accelerator opening; k is a radical of_(p,q)Fitting polynomial coefficients; omega_eIs the engine speed.

In the modeling of the longitudinal dynamics of the vehicle, the model is properly simplified on the premise of ensuring the accuracy, nonlinear factors such as high-order dynamic characteristics, mechanical clearance, torsional deformation and the like of an engine and a transmission system are ignored, the sliding friction of a clutch is not considered, and the shifting impact is supposed to be instantly completed and ignored in the shifting process, namely, the analytic expression of the longitudinal dynamics model of the whole vehicle is obtained according to the balance relation between the driving force and the resistance in the driving process of the vehicle, as shown in the formula (3).

Wherein v is the vehicle speed; i.e. i_gThe gear ratio of the current gear is set; i.e. i₀Is a main reduction ratio of η_TThe transmission efficiency of the whole system is improved; m is the mass of the automobile; g is the acceleration of gravity; f is a rolling resistance coefficient; i is a ramp coefficient; c_DIs the windward resistance coefficient; a is the windward area; ρ is the air density; r is the rolling radius of the wheel; j. the design is a square_wIs the moment of inertia of the wheel; j. the design is a square_eIs the rotational inertia of the engine.

Step 2: obtaining the current driving position and the current ramp of the vehicle by utilizing a high-precision map and navigation information, obtaining ramp information of roads in a driving path within a distance in the future according to the driving destination of the vehicle, dispersing the ramp information into N sections according to the distance length h, and inputting the N sections into the system

And step 3: under the condition that the global path information is known, the main disturbance amount of gear shifting is predicted to be the vehicle speed, therefore, the vehicle speed is planned in the global state from the initial place to the destination, a discrete planning mode is adopted under the cruise working condition (namely, according to the road condition information of each section, the overall optimal speed track is solved by a formula (3) in a subsection mode), the speed track is used as a speed terminal constraint condition in the prospective gear shifting solving, thus, the double optimization of the cruise speed and the transmission gear can be realized, and the energy-saving effect of a control strategy is further improved from the global angle;

and 4, step 4: the method comprises the following steps of optimizing target gears in a rolling mode in a limited control time domain by adopting a dynamic programming algorithm, dynamically programming from an initial state direction and/or an end state direction, and obtaining an optimal gear shifting control sequence, wherein the optimal gear shifting control sequence comprises the following steps:

starting from the initial stage 0 and/or the end stage N, acquiring index function values of each corresponding stage according to all possible states of the vehicle and gear-shifting control instructions in the stage, and determining the optimal gear and the corresponding gear-shifting control instruction in the stage;

acquiring corresponding stage index function values when different control instructions are acquired according to the vehicle states of all stages meeting the state transition relation along with the sequential increasing and/or decreasing of the stages, respectively accumulating the current stage and all the acquired stage index function values according to the state transition relation to obtain process index function values, and determining an optimal gear shifting instruction;

determining an optimal gear shifting control sequence until the end stage N and/or the initial stage 0;

wherein the stage index function is:

and/or

Process index function J_kComprises the following steps:

J_k＝J_k-1+Δm_f(x (k), u (k)); and/or

J_k＝J_k+1+Δm_f(x(k),u(k))；

Wherein the content of the first and second substances,

is the instantaneous fuel consumption of the engine, v is the vehicle speed, J_kIs the process index function at phase k, Δ m_f(x (k), u (k)) is a phase index function for phase k, α is a weight for travel time in process, β is a weight for fuel consumption in process, d_sIs the discrete length of the segment, x (k) is the vehicle state, u (k) is the shift control command;

the vehicle state is:

x(k)＝[g(k),v(k)]^T；

wherein, 1 is less than or equal to g (k) is less than or equal to 12;

0≤v(k)≤v_sikmax；

g (k) is gear; v (k) is vehicle speed; u (k) is a shift command, with 0 representing no shift, 1 representing an upshift, and-1 representing a downshift;

for vehicle start and end state constraints, v_sikmaxIs the maximum value in the vehicle speed trajectory for stage k in the optimal speed trajectory.

And 5: and sequentially recursion to determine the optimal state track of the vehicle by combining the initial state of the vehicle and the optimal gear shifting control sequence, namely sequentially recursion once to determine the vehicle speed and the throttle opening information corresponding to the corresponding gear shifting moment according to the optimal gear shifting control sequence and the initial state of the vehicle, and obtaining the optimal gear shifting sequence corresponding to the whole cycle working condition. And further obtaining the optimal gear shifting point under the circulation working condition.