CN118124568A - Semitrailer self-adaptive cruise longitudinal control method and device - Google Patents

Abstract

The application discloses a semitrailer self-adaptive cruise longitudinal control method and device, and relates to the technical field of automobile control. The control method comprises the following steps: acquiring real-time speed, vehicle structural state and expected acceleration of a target vehicle, and calling a torque calibration database to obtain expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; acquiring the current actual acceleration of a target vehicle; performing proportional integral control on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque; obtaining a final request engine torque according to the expected torque and the feedback control torque; controlling the target vehicle to run according to the requested engine torque; the method can cover torque output of the semitrailer under various running conditions, and simultaneously, a feedback control link with torque is added for bridging the ramp resistance under the real road environment, so that the longitudinal control effect is improved.

Description

Semitrailer self-adaptive cruise longitudinal control method and device

Technical Field

The disclosure relates generally to the technical field of automobile control, and in particular relates to a semitrailer self-adaptive cruise longitudinal control method and device.

Background

Semitrailers are a common type of truck consisting of a truck head and one or more trailers. Based on the special structure, the semitrailer correspondingly has various working condition modes, such as an empty head, an empty head belt hanging and different loading working conditions under which the head belt is empty.

In the existing self-adaptive cruise control algorithm, hierarchical control is generally adopted, an upper algorithm plans a target acceleration according to a target state, a road state and a vehicle state, and a lower algorithm outputs a desired torque to an engine according to the target acceleration and a desired deceleration to an electronic brake system (Electronic Brake Systems, EBS), so that the vehicle acceleration is as close to the desired acceleration as possible.

However, the semitrailer is different from the passenger car, the transmission efficiency, the rolling resistance coefficient and the air resistance coefficient of the semitrailer are changed along with the change of the self-vehicle weight and the structural change of the hung car, the measurement process of the parameters is complex, and the longitudinal control difficulty of the semitrailer commercial car is increased because the parameters directly influence the control effect of the longitudinal power of the whole car, therefore, the self-adaptive cruise longitudinal control method of the semitrailer is provided for solving the problems.

Disclosure of Invention

In view of the foregoing drawbacks and deficiencies of the prior art, it is desirable to provide a method and apparatus for adaptive cruise longitudinal control of a semitrailer.

In a first aspect, the present application provides a semitrailer adaptive cruise longitudinal control method, the control method comprising:

Acquiring a real-time speed, a vehicle structural state and an expected acceleration of a target vehicle, and calling a torque calibration database to obtain an expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value;

acquiring the current actual acceleration of the target vehicle;

Performing proportional integral control on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque;

Obtaining a final request engine torque according to the expected torque and the feedback control torque;

controlling the target vehicle to run according to the requested engine torque;

The torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the corresponding torques of the sliding deceleration, the steady-speed torque and the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.

According to the technical scheme provided by the application, the three test working conditions comprise: the first test condition, the second test condition and the third test condition; the first test working condition is used for calibrating the sliding deceleration; the second test working condition is used for calibrating the steady-speed torque; the third test working condition is used for calibrating torque corresponding to the maximum expected acceleration;

The target vehicle is a semitrailer and at least has three vehicle structural states of empty headstock, headstock belt empty hanging and full vehicle loading;

Establishing the torque calibration database based on the first test condition comprises the following steps:

Accelerating the target vehicle in different vehicle structural states to ACC maximum speed limit on a straight road respectively, and keeping the gear of the target vehicle in D gear;

The accelerator pedal of the target vehicle is released, the target vehicle is controlled to be decelerated from the maximum speed limit speed of the ACC to the speed of 0, and sliding deceleration at different speeds in the deceleration process is recorded;

constructing a sliding deceleration table according to all the sliding decelerations acquired under different vehicle structural states; the slip deceleration table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a slip deceleration corresponding to each of the vehicle speed values.

According to the technical scheme provided by the application, the torque calibration database is established based on the second test working condition, and comprises the following steps:

Respectively acquiring the steady-speed torque output by the engine of the target vehicle when the target vehicle in different vehicle structural states stably runs on a flat road at different speeds;

Constructing a speed stabilizing torque table according to all the obtained speed stabilizing torques under different vehicle structural states; the steady speed torque meter includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a steady speed torque corresponding to each of the vehicle speed values.

According to the technical scheme provided by the application, the torque calibration database is established based on the third test working condition, and comprises the following steps:

Respectively acquiring engine output torque when the vehicle reaches the maximum expected acceleration of ACC when the target vehicle in different vehicle structural states runs on a flat road at different speeds;

Constructing a torque table corresponding to the maximum expected acceleration according to the torques corresponding to all the maximum expected accelerations obtained under different vehicle structural states; the maximum desired acceleration versus torque table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a torque corresponding to a maximum desired acceleration corresponding to each of the vehicle speed values.

According to the technical scheme provided by the application, the torque calibration database is established based on three test working conditions, and specifically comprises the following steps:

and constructing the torque calibration database based on the sliding deceleration table, the steady speed torque table and the maximum expected acceleration corresponding torque table.

According to the technical scheme provided by the application, the method further comprises the following steps:

acquiring a real-time vehicle speed, a vehicle structural state and a required deceleration of the target vehicle, and inquiring the sliding deceleration meter to obtain a sliding deceleration corresponding to the vehicle structural state and the real-time vehicle speed;

and if the required deceleration is smaller than the sliding deceleration, controlling the EBS of the target vehicle to perform braking.

According to the technical scheme provided by the application, proportional integral control is performed on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque, and the method specifically comprises the following steps:

Calculating a difference between the actual acceleration and the expected acceleration, and inputting the difference to a PID controller of the target vehicle;

And receiving feedback control torque output by the PID controller.

According to the technical scheme provided by the application, the expected acceleration and the required deceleration are sent out by an ACC control system of the target vehicle.

In a second aspect, an embodiment of the present application provides a semitrailer adaptive cruise longitudinal control device, including:

The acquisition module is used for acquiring the real-time speed, the vehicle structural state and the expected acceleration of the target vehicle, and calling a torque calibration database to obtain the expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value;

the acquisition module is also used for acquiring the current actual acceleration of the target vehicle;

The PID control module is used for performing proportional integral control on the engine execution torque based on the difference value between the expected acceleration and the actual acceleration to obtain feedback control torque;

The torque processing module is used for obtaining the final request engine torque according to the expected torque and the feedback control torque;

the vehicle control module is used for controlling the target vehicle to run according to the request engine torque;

The torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the corresponding torques of the sliding deceleration, the steady-speed torque and the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.

In summary, the technical scheme specifically discloses a semitrailer self-adaptive cruise longitudinal control method and device, and the control method comprises the following steps: acquiring real-time speed, vehicle structural state and expected acceleration of a target vehicle, and calling a torque calibration database to obtain expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value; acquiring the current actual acceleration of the target vehicle, performing proportional integral control on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque, and finally, obtaining the request engine torque finally used for controlling the target vehicle to execute according to the expected torque and the feedback control torque; the torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the sliding deceleration, the steady-speed torque and the torque corresponding to the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.

Therefore, in the method, the expected torque corresponding to different vehicle structural states, different real-time vehicle speeds and different expected accelerations can be obtained through the torque calibration database, and various complex working conditions of the semi-trailer can be effectively covered; after the corresponding expected torque is obtained, the feedback control torque is obtained based on the expected acceleration and the actual acceleration, so that the final request engine torque is formed together with the expected torque.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:

Fig. 1 is a schematic flow chart of a semitrailer adaptive cruise longitudinal control method.

Fig. 2 is a schematic flow chart of a first test condition in a semitrailer adaptive cruise longitudinal control method.

Fig. 3 is a schematic flow chart of a second test condition in the semitrailer adaptive cruise longitudinal control method.

Fig. 4 is a schematic flow chart of a third test condition in the semitrailer adaptive cruise longitudinal control method.

Fig. 5 is a schematic flow chart of step S300 in a method for adaptive cruise longitudinal control of a semitrailer.

Fig. 6 is a schematic structural view of a semitrailer adaptive cruise longitudinal control device.

Reference numerals in the drawings: 100. a longitudinal control device; 101. an acquisition module; 102. a PID control module; 103. a torque processing module; 104. a vehicle control module.

Detailed Description

The application is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting of the application. It should be noted that, for convenience of description, only the portions related to the application are shown in the drawings.

It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.

First, a brief technical description will be given for the convenience of understanding the implementation of the present application.

The method comprises a target vehicle, wherein the target vehicle is a semitrailer (semi-trailer commercial vehicle), and the semitrailer is a common truck type and consists of a locomotive and one or more trailers. Based on the specificity of the semitrailer structure, the target vehicle at least has three vehicle structure states of an empty head, a head belt empty hanger and a full vehicle.

An adaptive cruise control system (Adaptive Cruise Control, ACC) is developed on the basis of cruise control technology. Besides the running according to the speed set by the driver, the vehicle-following distance can be kept preset, and the automatic acceleration and deceleration functions along with the change of the vehicle distance can be realized.

In the adaptive cruise control algorithm, hierarchical control is generally adopted, wherein an upper algorithm plans a target acceleration according to a target state, a road state and a vehicle state, and a lower algorithm outputs a desired torque to an engine, and a desired deceleration to an electronic brake system (Electronic Brake Systems, EBS) according to the target acceleration, so that the vehicle acceleration is as close to the desired acceleration as possible. In outputting the desired torque, the reaction torque is generally performed using a longitudinal dynamics formula, specifically, see the following formulas (1) to (4):

Formula (1)

Wherein,Expressed as mass of the whole vehicle; /(I)Expressed as the rate of change of speed; /(I)Expressed as driving force; /(I)Expressed as rolling resistance; /(I)Expressed as air resistance; /(I)Expressed as ramp resistance.

Formula (2)

Wherein,Expressed as engine output torque; /(I)Represented as a transmission gear ratio; /(I)Expressed as final drive ratio; /(I)Expressed as transmission efficiency; /(I)Expressed as tire radius.

Rolling resistanceExpressed as:

Formula (3)

Wherein,Represented as the weight of the vehicle; /(I)Expressed as a rolling resistance coefficient.

Air resistanceExpressed as:

Formula (4)

Wherein,Expressed as an air resistance coefficient; /(I)Expressed as the frontal area of the vehicle; /(I)Expressed as air density; /(I)Represented as real-time vehicle speed.

Based on the above description, if all the parameters in the above formula can be accurately obtained, the expected torque can be reversely deduced through the current expected acceleration, but the semitrailer is different from the passenger car, the transmission efficiency, the rolling resistance coefficient and the air resistance coefficient of the semitrailer are all changed along with the change of the self-vehicle weight and the structural change of the hung vehicle, the measurement process of the parameters is complex, and the longitudinal control difficulty of the semitrailer commercial car is increased because the control effect of the longitudinal power of the whole car is directly influenced.

In view of the above, an embodiment of the present application provides a method for adaptive cruise longitudinal control of a semitrailer, which obtains a final requested engine torque by combining feedforward and feedback control, wherein a torque calibration database is established by calibrating the running resistance and acceleration capacity of the whole trailer, the feedforward control torque is obtained by the torque calibration database, and the feedback control torque is obtained by proportional integral control of the acceleration difference and PID.

Specifically, referring to fig. 1, a flow chart of a method for adaptive cruise longitudinal control of a semitrailer according to the present embodiment includes:

S100, acquiring real-time speed, vehicle structural state and expected acceleration of a target vehicle, and calling a torque calibration database to obtain expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value;

The torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the corresponding torques of the sliding deceleration, the steady-speed torque and the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.

The establishment of the torque calibration database is explained below.

Firstly, the three test conditions specifically include: the first test condition, the second test condition and the third test condition; the first test working condition is used for calibrating the sliding deceleration; the second test working condition is used for calibrating the steady-speed torque; and the third test working condition is used for calibrating the torque corresponding to the maximum expected acceleration.

(1) First test condition: slip deceleration test

Referring to fig. 2, under the first test condition, the method includes the following test steps:

S110, accelerating the target vehicle in different vehicle structural states to the ACC maximum speed limit on a straight road respectively, and keeping the gear of the target vehicle in a D gear;

It is simply understood that this process is equivalent to accelerating the target vehicle in three vehicle structural states of empty head, empty head with hanging and full vehicle loading to the ACC maximum speed limit on a straight road, respectively, and meanwhile, since one of the conditions for ACC start is that the vehicle gear is D gear, N gear will cause ACC to exit, the gear of the vehicle needs to be kept D gear in the whole process.

S111, controlling the target vehicle to be decelerated from the ACC maximum speed limit vehicle speed to 0 by loosening an accelerator pedal of the target vehicle, and recording sliding decelerations at different vehicle speeds in the deceleration process;

Slip deceleration refers to a speed at which the vehicle decreases due to frictional resistance during running.

In order to record the sliding deceleration at different vehicle speeds, the accelerator pedal is required to be released, the vehicle is made to slide and decelerate, and the data acquisition device is used for recording the deceleration of the target vehicle at different vehicle speeds; specifically, the deceleration may be recorded at every 10km/h of the vehicle speed.

The data acquisition and calibration process may be performed in concert by a vehicle body electronic stability control system (Electronic Stability Controller, ESC), an engine management system (ENGINE MANAGEMENT SYSTEM, EMS), a vehicle stability assistance system (Vehicle Stability Assist, VSA), and instrumentation onboard the vehicle.

S112, constructing a sliding deceleration table according to all the sliding decelerations acquired under different vehicle structural states; the slip deceleration table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a slip deceleration corresponding to each of the vehicle speed values.

In some examples, the slip deceleration table may be as shown in table 1 below.

TABLE 1 sliding deceleration Meter

Wherein the vehicle structural states 1-3 in table 1 represent three vehicle structural states of the target vehicle, respectively; [...]、[/>.../>]、[/>.../>And each represents a slip deceleration corresponding to each vehicle speed value in different vehicle structural states.

Meanwhile, as can be seen from the foregoing, the vehicle sliding deceleration measured based on the first test condition includes the deceleration of the target vehicle caused by the air resistance, rolling resistance and engine anti-dragging resistance (D gear) of the vehicle under different speeds and different structural states (empty head, empty head belt and full vehicle).

(2) Second test condition: constant speed torque test

Referring to fig. 3, under the second test condition, the method includes the following test steps:

S120, respectively acquiring steady-speed torque output by an engine of the target vehicle when the target vehicle in different vehicle structural states stably runs on a flat road at different vehicle speeds;

The steady-speed torque is the torque output from the engine when the vehicle is traveling at a steady speed.

The method is simple to understand, the process is equivalent to that on a straight road, a data acquisition device respectively acquires the steady-speed torque output by an engine when a target vehicle in three structural states of an empty vehicle head, a vehicle head with an empty suspension and a vehicle with a full load stably runs at different speeds; specifically, the torque of the engine output may be recorded at every 10km/h of the vehicle speed.

For example, on a straight road, the torque output by an engine when an empty vehicle head, a vehicle head belt is hung in an empty state and the vehicle is stably driven at 1, 10, 20 and … km/h is respectively collected, and the torque under each vehicle speed value can be obtained by taking an average value in a certain time after the vehicle speed is stably controlled by a driver.

S121, constructing a speed stabilizing torque table according to all the obtained speed stabilizing torques under different vehicle structural states; the steady speed torque meter includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a steady speed torque corresponding to each of the vehicle speed values.

In some examples, the steady speed torque table may be as shown in table 2 below.

Table 2 steady speed torque meter

Wherein the vehicle structural states 1-3 in table 2 represent three vehicle structural states of the target vehicle, respectively; [...]、[/>.../>]、[/>.../>And the steady speed torque corresponding to each vehicle speed value under different vehicle structural states is respectively represented.

(3) Third test condition: torque testing corresponding to the maximum expected acceleration;

referring to fig. 4, under the third test condition, the method includes the following test steps:

S130, respectively acquiring engine output torque when the vehicle reaches the maximum expected acceleration of the ACC when the target vehicle in different vehicle structural states runs on a flat road at different speeds;

the maximum desired acceleration of the ACC system refers to the maximum acceleration that the ACC system can achieve, which is set based on the performance of the vehicle and the specifications of the system.

Simply and easily understood, the process is equivalent to respectively acquiring the output torque of the engine when the target vehicle in three structural states of an empty vehicle head, a vehicle head with an empty suspension and a vehicle full load reaches the maximum expected acceleration of the ACC under different vehicle speeds by the data acquisition device; specifically, it is also possible to record the output torque once every 10km/h of the vehicle speed.

For example, on a straight road, the output torque of the engine is collected when the vehicle head is empty, the vehicle head is hung empty and the vehicle is fully loaded at 1, 10, 20 and … km/h to reach the maximum expected acceleration of ACC.

The output torque can be obtained by a trial and error method, for example, assuming that the maximum expected acceleration of the ACC is 1m/s ², the vehicle structure state and the real-time vehicle speed are respectively: the head of the vehicle is empty and hung at 40km/h; at this time, 30%, 40% and 50% of torque are respectively requested from the engine, acceleration of the target vehicle is observed until the requested torque is found when the vehicle acceleration is just 1m/s ², that is, the output torque of the engine when the maximum desired acceleration of the ACC is reached at the vehicle speed.

S131, constructing a torque table corresponding to the maximum expected acceleration according to the torques corresponding to all the maximum expected accelerations obtained under different vehicle structural states; the maximum desired acceleration versus torque table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a torque corresponding to a maximum desired acceleration corresponding to each of the vehicle speed values.

In some examples, the maximum desired acceleration versus torque table may be as shown in table 3 below.

TABLE 3 maximum desired acceleration versus torque meter

Wherein the vehicle structural states 1-3 in table 3 represent three vehicle structural states of the target vehicle, respectively; [.../>]、[/>.../>]、[/>.../>Each represents the engine output torque at which each vehicle speed reaches the maximum desired acceleration in the different vehicle structural states.

After the slip deceleration meter, the steady speed torque meter and the maximum expected acceleration corresponding torque meter are constructed, the torque calibration database can be constructed based on the slip deceleration meter, the steady speed torque meter and the maximum expected acceleration corresponding torque meter.

Specifically, after the testing process, the sliding deceleration meter, the steady speed torque meter and the torque meter corresponding to the maximum expected acceleration are obtained, 33 one-dimensional tables can be obtained, wherein the number of empty vehicle head structural states is 11, the number of vehicle head carrying empty hanging structural states is 11, the number of vehicle full-load structural states is 11, and the 11 one-dimensional tables under each working condition represent that the vehicle speed is from 1km/h to 100km/h; for example, taking the vehicle structural state 3 as an example of the vehicle full load, the vehicle structural state of the target vehicle is the vehicle full load, and the one-dimensional acceleration torque correspondence table at the vehicle speed of 20km/h may be shown in the following table 4.

Table 4 acceleration torque mapping table

Taking this acceleration torque correspondence table as an example, acceleration correspondence tables corresponding to different vehicle structural states and different vehicle speeds can be obtained based on the slip deceleration table, the steady speed torque table, and the maximum expected acceleration correspondence torque table, and may be an acceleration torque correspondence table corresponding to a vehicle full load and a vehicle speed of 10km/h, an acceleration torque correspondence table corresponding to an empty vehicle head and a vehicle speed of 60km/h, an acceleration torque correspondence table corresponding to an empty vehicle head and a vehicle speed of 80km/h, or the like.

In some examples, the structure of the torque calibration database may be as shown in table 5 below, and the torque calibration database may construct a corresponding linear relationship based on all calibration data, so as to achieve that when the desired acceleration planned by the ACC system is any one value from the sliding acceleration to the ACC maximum request acceleration, the corresponding desired torque may be obtained. Meanwhile, the expected torque is the feedforward control torque in the feedforward control torque obtained through the torque calibration database.

Table 5 torque calibration database

Taking the vehicle structural state of the target vehicle as the vehicle full load and the vehicle speed as 30km/h, the obtained acceleration torque corresponding table actual data is exemplified as shown in the following table 6, and the corresponding acceleration-torque linear relation is constructed according to the following three nodes, so that the expected torques under different expected accelerations can be obtained under the conditions that the vehicle is full load and the vehicle speed is 30km/h, for example, if the expected acceleration is 0.45 at the moment, the corresponding expected torque is 55%; if the desired acceleration is-0.1, the desired torque is 5%.

TABLE 6 acceleration torque mapping table for vehicle full load and vehicle speed of 30km/h

It should be noted that in the above three test conditions, the defined data acquisition node is recorded once every 10km/h of the vehicle speed, so that the vehicle speed interval is also used for the subsequent development, but in the actual test process, the desired torque corresponding to each vehicle speed value can be obtained finally by linear relation among the data or acquisition with shorter vehicle speed interval.

For example, if the vehicle is fully loaded by the linear correspondence, the vehicle speed is 30km/h, the expected acceleration is 0.45, the corresponding expected torque is 55%, and the vehicle is fully loaded, the vehicle speed is 40km/h, the expected acceleration is 0.45, the corresponding expected torque is 60%, then the vehicle is fully loaded, the vehicle speed is 35km/h, and the expected torque is 57.5% when the expected acceleration is 0.45, which is a process of obtaining the expected torques at different vehicle speeds by the linear correspondence of the vehicle speed and the expected torque.

The vehicle body of the semi-trailer commercial vehicle shakes greatly in the driving process, the accuracy of a sensor used by the semi-trailer commercial vehicle is usually not high, and the difficulty of estimating the gradient in real time is high, so that the desired acceleration on the ramp is difficult to achieve only through the feedforward control torque.

S200, acquiring the current actual acceleration of the target vehicle;

The actual acceleration is used for determining an error requiring feedback control to be bridged, the feedforward control torque output obtained through the torque calibration database can ensure that the target vehicle runs according to the expected acceleration, but when the target vehicle runs on a downhill slope, the actual acceleration of the vehicle and the expected acceleration are deviated due to the ramp resistance.

S300, performing proportional integral control on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque;

In the present embodiment, proportional-integral control is performed by a PID controller for quickly responding to a change in error and eliminating steady-state error by an integral action; in the embodiment of the application, the input of the PID controller is the difference between the expected acceleration and the actual acceleration The output Torque is the engine execution Torque obtained by feedback control, namely the feedback control Torque, and the normal range is 0-100.

Specifically, referring to fig. 5, step S300 is further developed, and includes the following steps S301 and S302.

S301, calculating a difference value between the actual acceleration and the expected acceleration, and inputting the difference value to a PID controller of the target vehicle;

the PID controller is composed of The corresponding process of obtaining the feedback control torque is as follows: proportional control, integral control and differential control; wherein, since the differential term in the differential control is zero, the feedback control torque is mainly obtained by means of proportional control and integral control in the implementation of the application.

Specifically, the PID controller performs proportional control based on the following formula (5), thereby obtaining a torque after proportional control。

Formula (5)

Wherein,The difference between the expected acceleration and the actual acceleration is a known term, namely the current, expected acceleration and the actual acceleration of the target vehicle; /(I)The method is to calibrate the quantity, and in the actual execution process, a table look-up mode is adopted to find out the corresponding proportionality coefficient/>, according to the current body weight of the target vehicle，/>Determines the speed of torque up and down, and is the same/>Lower/>The larger the torque variation the faster.

Then, the PID controller performs integral control based on the following formula (6) to obtain an integral-controlled torque。

Formula (6)

Wherein,And/>In the actual execution process, a table look-up mode is adopted to find out the corresponding integral coefficient/>, according to the current body weight of the target vehicle, for the quantity to be calibrated，/>The speed of the torque up and down is determined.

The following is a pair ofAnd/>Is briefly described.

In the embodiment of the application, only the calibration is actually requiredAnd/>Two values.

First, the following needs to be noted in the calibration process:

(A1). The value is not too large, and the value is 0-30 in the actual calibration, because the vehicle body of the semi-trailer commercial vehicle shakes greatly, the sensor noise is large, and the calculated actual acceleration of the vehicle has larger noise, so/> There will be some noise due to/>Direct and/>Multiplied and output as part of the feedback control torque,/>Excessive amounts can result in output torque having a relatively large amount of noise.

(A2).The value then needs to ensure that the vehicle can reach the corresponding speed while avoiding the generation of a large overshoot;

Overshoot refers to the extent to which the system responds beyond a set point or target value, which may cause occupant discomfort or safety problems during vehicle acceleration, and thus, is positive Corresponding/>And negative/>Unlike, usually negative values correspond/>Greater than positive value corresponds to/>。

(A3) The weight of semi-trailer commercial vehicle body is very different between full load and no load, so that it is necessary to use different weightAnd/>The embodiment of the application is to calibrate the corresponding/>, by the weight of the vehicle bodyAnd/>。

In some embodiments, in particularAnd/>The value calibration process is as follows;

The target vehicles in the three vehicle structural states of empty vehicle head, vehicle head belt empty hanging and vehicle full loading are respectively carried out once in the following parameter calibration test working conditions to obtain three groups And/>Values.

Parameter calibration test working condition: the target vehicles in different vehicle structural states run at a constant speed of 20km/h on a flat road by using an ACC system, simultaneously the feedforward link of the ACC is closed, the output engine executing torque is provided by the feedback link only, and an initial one is set、/>/>Here/>Corresponding to positive/>，/>Corresponding to minus/>。

Subsequently, the set speed of the target vehicle is adjusted to 30km/h, the reaction of the target vehicle is observed, and the reaction of the target vehicle is initiated、/>/>The adjustment is performed until a desired vehicle response is obtained, optionally the desired vehicle response is that the vehicle reaches a vehicle speed of 30km/h after 10s and the vehicle speed overshoot does not exceed 1km/h.

It should be noted that in the parameter adjustment process, parameters are adjusted according to different methods corresponding to different vehicle reactions, for example, if the target vehicle is accelerating too slowly (reaching 30km/h speed over 10 s), the speed is increased、/>Is a numerical value of (2); if the target vehicle speeds up too fast (reaches 30km/h speed too early), then decrease/>、/>Is a numerical value of (2); if the target vehicle overshoots too much (exceeding 31 km/h), then increase/>。

As can be seen from the above description, three sets of parameter calibration values under different vehicle structural states can be obtained、/>/>) And the three sets of parameter calibration values correspond to three vehicle body weights; based on the linear relation formed by the parameter calibration value and the weight of the vehicle body, in the practical application process, the/> which should be used in the feedback control link can be obtained according to the current weight of the vehicle bodyAnd/>Values.

S302, receiving feedback control torque output by the PID controller;

the feedback control torque corresponds to the torque after proportional control Torque after integral control/>Is added to the value of (a).

S400, obtaining the final requested engine torque according to the expected torque and the feedback control torque.

Through the foregoing steps, when both the feedforward control torque and the feedback control torque have been obtained, the final requested engine torque can be obtained by adding the feedforward control torque and the feedback control torque.

For example, the desired torque obtained by the feed-forward control loop isWhile the PID controller outputs feedback control torque/>, based on the difference between the current actual acceleration of the target vehicle and the expected acceleration of the ACC system planThen the final requested engine torque is/> 。

S500, controlling the target vehicle to run according to the requested engine torque;

upon receiving the requested engine torque, the EMS may be controlled to respond to and control the engine of the target vehicle to operate with the requested engine torque.

In some embodiments, the vehicle structural state further includes a half-load state, i.e. a load state between a vehicle head-mounted empty state and a vehicle full load state (a vehicle head-mounted empty state and a certain load state but not a full load state), and in this case, the control method may further obtain the requested engine torque through the vehicle weight, and in combination with the above description of the parameter calibration test in the feedback control process, it is necessary to find the corresponding proportionality coefficient according to the vehicle weight in the feedback control link，/>The value is mainly highlighted here, and the expected torque under different vehicle weights can be obtained and described according to the linear relation of the vehicle weight and the expected torque in the feedforward control link, and the torque calibration database also comprises vehicle weight data;

Meanwhile, the control method specifically comprises the following steps:

Acquiring the real-time speed, the real-time weight and the expected acceleration of the target vehicle, and calling the torque calibration database to obtain the expected torque corresponding to the real-time speed, the real-time weight and the expected acceleration; the weight of the vehicle is used for recording the current weight of the whole vehicle of the target vehicle, so that the load condition of the target vehicle can be indirectly reflected.

Further, the torque calibration database is built based on the three test conditions, and the current real-time vehicle weight of the current target vehicle is recorded only in the second test condition and the third test condition;

For example, in the second test condition, the head strap is empty to hang at 20t; and in the third test condition, the vehicle is fully loaded at 40t; the expected torques of the vehicle weight 20t and the vehicle weight 40t under different vehicle speeds and different expected accelerations can be obtained based on the constructed acceleration torque corresponding table, and at the moment, the torque calibration database can construct a linear relation between the vehicle weight and the expected torque according to corresponding calibration data, so that the expected torques under different vehicle weights can be obtained, and data capable of obtaining the expected torques through calibrating the vehicle weights are formed.

Taking the example that the vehicle is full (40 t of the vehicle weight) and the vehicle speed is 30km/h, the expected torque corresponding to the expected acceleration is 0.45 is 55%, the vehicle head is empty (20 t of the vehicle weight) and the vehicle speed is 30km/h, the expected torque corresponding to the expected acceleration is 0.45 is 35%, at this time, the vehicle weight is 30t according to the linear relation between the vehicle weight and the expected torque formed by the data, and the corresponding expected torque is 45% when the vehicle speed is 30km/h and the expected acceleration is 0.45.

Subsequently, the feedback control after obtaining the desired torque according to the vehicle weight and the process of controlling the engine to operate with the requested engine torque are consistent with the principles of the foregoing steps S200, S300, S400 and S500, and will not be described herein.

In some embodiments, during ACC control, to improve energy efficiency and service life of the braking system, engine back-dragging torque should be utilized as much as possible for braking.

The engine anti-dragging torque refers to the torque generated by the engine when the driver releases the accelerator pedal or the vehicle is in a cruise control state, and the anti-dragging torque can enable the vehicle to reduce the speed of the vehicle through the friction force between the driving wheels and the ground.

However, if the vehicle is in emergency during running, and the engine reverse torque is insufficient to meet the current deceleration requirement of the vehicle, the EBS must be started to supplement the required braking effect for the safety of the running of the vehicle, so the control method further comprises the following steps:

A1, acquiring a real-time vehicle speed, a vehicle structural state and a required deceleration of the target vehicle, and inquiring the sliding deceleration meter to obtain a sliding deceleration corresponding to the vehicle structural state and the real-time vehicle speed;

the real-time speed and the vehicle structure state of the target vehicle are used for locking corresponding sliding deceleration in the sliding deceleration meter, so that the following comparison with the demanded deceleration planned by the ACC system according to the target state, the road state and the vehicle state is facilitated.

And A2, if the required deceleration is smaller than the sliding deceleration, controlling the EBS of the target vehicle to perform braking.

The sliding deceleration is consistent with the deceleration principle generated by the anti-dragging torque, so that the anti-dragging torque can be judged whether to meet the current deceleration requirement of the target vehicle by comparing the planned required deceleration with the sliding deceleration.

When the required deceleration is smaller than the sliding deceleration, the situation that the anti-dragging torque cannot meet the current deceleration requirement of the target vehicle is judged, and the EBS is required to be called in time for braking, so that the running safety of the vehicle is ensured; otherwise, the current deceleration requirement of the target vehicle can be met through the anti-dragging torque, and the EBS is not required to be started for braking.

Based on the above description, the embodiment of the application provides a semitrailer self-adaptive cruise longitudinal control method, in the method, firstly, the real-time speed, the vehicle structural state and the expected acceleration of a target vehicle are obtained, and a torque calibration database is called to obtain the expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database is established based on three test working conditions, and can obtain expected torque required by target vehicles in different vehicle structural states under any real-time vehicle speed, any expected acceleration and any vehicle weight; in the subsequent process, in order to eliminate the ramp resistance caused by the road environment, the desired torque is obtained, the requested engine torque is also needed to be obtained by combining with the feedback control torque, the current actual acceleration of the target vehicle is needed to be obtained in the calculation process of the feedback control torque, and then the proportional integral control is carried out on the engine execution torque based on the difference between the desired acceleration and the actual acceleration to obtain the feedback control torque; and finally, obtaining the required engine torque finally used for controlling the operation of the engine through the expected torque and the feedback control torque.

On one hand, the method can obtain the expected torque required by the target vehicle with different vehicle structural states under any real-time speed, any expected acceleration and even any vehicle weight through the establishment of the torque calibration database, so that the complex parameter measurement process is avoided, various complex working conditions of the semi-trailer are covered, and the comprehensiveness of the control result is ensured; in the second aspect, the method also shows a feedback control link to bridge the deviation between the actual acceleration of the vehicle, caused by the resistance of the ramp, and the expected acceleration of the vehicle when the vehicle runs on the ramp, and finally, the requested engine torque is obtained through the feedback control torque and the expected torque, so that the vehicle can obtain a more accurate control effect; and finally, the torque calibration database is established by marking key node data in three test working conditions and constructing a linear relation among the data, so that the calibration workload is effectively reduced and the calibration efficiency is improved by adopting the construction mode.

The method for adaptively controlling the longitudinal cruising of the semitrailer according to the embodiment of the application is described in detail above with reference to fig. 1 to 5, and the device according to the embodiment of the application is described below with reference to the accompanying drawings.

As shown in fig. 6, the schematic structural diagram of a semitrailer adaptive cruise longitudinal control device according to an embodiment of the present application is applied to the above longitudinal control method, and the longitudinal control device 100 includes:

The acquiring module 101 is configured to acquire a real-time vehicle speed, a vehicle structural state and an expected acceleration of a target vehicle, and call a torque calibration database to obtain an expected torque corresponding to the real-time vehicle speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value;

The acquiring module 101 is further configured to acquire a current actual acceleration of the target vehicle;

The PID control module 102 is used for performing proportional integral control on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque;

the torque processing module 103, wherein the torque processing module 103 is configured to obtain a final requested engine torque according to the desired torque and the feedback control torque;

A vehicle control module 104, the vehicle control module 104 configured to control an engine operation of the target vehicle according to the requested engine torque;

The torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the corresponding torques of the sliding deceleration, the steady-speed torque and the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.

In some embodiments, the three test conditions include: the first test condition, the second test condition and the third test condition; the first test working condition is used for calibrating the sliding deceleration; the second test working condition is used for calibrating the steady-speed torque; the third test working condition is used for calibrating torque corresponding to the maximum expected acceleration;

The target vehicle is a semitrailer and at least has three vehicle structural states of empty headstock, headstock belt empty hanging and full vehicle loading;

Establishing the torque calibration database based on the first test condition comprises the following steps: accelerating the target vehicle in different vehicle structural states to ACC maximum speed limit on a straight road respectively, and keeping the gear of the target vehicle in D gear;

The accelerator pedal of the target vehicle is released, the target vehicle is controlled to be decelerated from the maximum speed limit speed of the ACC to the speed of 0, and sliding deceleration at different speeds in the deceleration process is recorded;

constructing a sliding deceleration table according to all the sliding decelerations acquired under different vehicle structural states; the slip deceleration table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a slip deceleration corresponding to each of the vehicle speed values.

In some embodiments, establishing the torque calibration database based on the second test condition includes: respectively acquiring the steady-speed torque output by the engine of the target vehicle when the target vehicle in different vehicle structural states stably runs on a flat road at different speeds;

Constructing a speed stabilizing torque table according to all the obtained speed stabilizing torques under different vehicle structural states; the steady speed torque meter includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a steady speed torque corresponding to each of the vehicle speed values.

In some embodiments, establishing the torque calibration database based on the third test condition includes: respectively acquiring engine output torque when the vehicle reaches the maximum expected acceleration of ACC when the target vehicle in different vehicle structural states runs on a flat road at different speeds;

Constructing a torque table corresponding to the maximum expected acceleration according to the torques corresponding to all the maximum expected accelerations obtained under different vehicle structural states; the maximum desired acceleration versus torque table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a torque corresponding to a maximum desired acceleration corresponding to each of the vehicle speed values.

And finally, constructing the torque calibration database based on the sliding deceleration table, the steady speed torque table and the torque table corresponding to the maximum expected acceleration.

In some embodiments, the obtaining module 101 is specifically further configured to obtain a real-time vehicle speed, a vehicle structural state, and a required deceleration of the target vehicle, and query the sliding deceleration table to obtain a sliding deceleration corresponding to the vehicle structural state and the real-time vehicle speed;

The vehicle control module 104 is specifically further configured to determine whether the required deceleration is smaller than the slip deceleration, and when it is determined that the required deceleration is smaller than the slip deceleration, control the EBS of the target vehicle to perform braking.

In some embodiments, the PID control module 102 is specifically configured to calculate a difference between the actual acceleration and the desired acceleration, and input the difference to a PID controller of the target vehicle, and then receive a feedback control torque output by the PID controller.

It should be noted that the longitudinal control apparatus 100 according to the embodiment of the present application may correspond to performing the method described in the embodiment of the present application, and the foregoing and other operations and/or functions of each module of the longitudinal control apparatus 100 are respectively for implementing the corresponding flow of the method in the embodiment shown in fig. 1, which is not repeated herein for brevity.

The above description is only illustrative of the preferred embodiments of the present application and of the principles of the technology employed. It will be appreciated by persons skilled in the art that the scope of the application referred to in the present application is not limited to the specific combinations of the technical features described above, but also covers other technical features formed by any combination of the technical features described above or their equivalents without departing from the inventive concept. Such as the above-mentioned features and the technical features disclosed in the present application (but not limited to) having similar functions are replaced with each other.

Claims (9)

1. A semitrailer adaptive cruise longitudinal control method, characterized in that the control method comprises:

Acquiring a real-time speed, a vehicle structural state and an expected acceleration of a target vehicle, and calling a torque calibration database to obtain an expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value;

acquiring the current actual acceleration of the target vehicle;

Performing proportional integral control on the engine execution torque based on the difference between the expected acceleration and the actual acceleration to obtain feedback control torque;

Obtaining a final request engine torque according to the expected torque and the feedback control torque;

controlling the target vehicle to run according to the requested engine torque;

The torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the corresponding torques of the sliding deceleration, the steady-speed torque and the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.

2. A semitrailer adaptive cruise longitudinal control method according to claim 1, characterized in that the three test conditions comprise: the first test condition, the second test condition and the third test condition; the first test working condition is used for calibrating the sliding deceleration; the second test working condition is used for calibrating the steady-speed torque; the third test working condition is used for calibrating torque corresponding to the maximum expected acceleration;

The target vehicle is a semitrailer and at least has three vehicle structural states of empty headstock, headstock belt empty hanging and full vehicle loading;

Establishing the torque calibration database based on the first test condition comprises the following steps:

Accelerating the target vehicle in different vehicle structural states to ACC maximum speed limit on a straight road respectively, and keeping the gear of the target vehicle in D gear;

The accelerator pedal of the target vehicle is released, the target vehicle is controlled to be decelerated from the maximum speed limit speed of the ACC to the speed of 0, and sliding deceleration at different speeds in the deceleration process is recorded;

constructing a sliding deceleration table according to all the sliding decelerations acquired under different vehicle structural states; the slip deceleration table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a slip deceleration corresponding to each of the vehicle speed values.

3. The method for adaptive cruise longitudinal control of a semitrailer according to claim 2, wherein establishing the torque calibration database based on the second test condition comprises:

Respectively acquiring the steady-speed torque output by the engine of the target vehicle when the target vehicle in different vehicle structural states stably runs on a flat road at different speeds;

Constructing a speed stabilizing torque table according to all the obtained speed stabilizing torques under different vehicle structural states; the steady speed torque meter includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a steady speed torque corresponding to each of the vehicle speed values.

4. A method of adaptive cruise longitudinal control of a semitrailer according to claim 3, wherein establishing the torque calibration database based on the third test condition comprises:

Respectively acquiring engine output torque when the vehicle reaches the maximum expected acceleration of ACC when the target vehicle in different vehicle structural states runs on a flat road at different speeds;

Constructing a torque table corresponding to the maximum expected acceleration according to the torques corresponding to all the maximum expected accelerations obtained under different vehicle structural states; the maximum desired acceleration versus torque table includes: different vehicle structural states, a plurality of vehicle speed values in each of the vehicle structural states, and a torque corresponding to a maximum desired acceleration corresponding to each of the vehicle speed values.

5. The method for adaptive cruise longitudinal control of a semitrailer according to claim 4, wherein the torque calibration database is established based on three test conditions, and specifically comprises:

and constructing the torque calibration database based on the sliding deceleration table, the steady speed torque table and the maximum expected acceleration corresponding torque table.

6. A method of adaptive cruise longitudinal control of a semitrailer according to claim 5, characterized in that the method further comprises:

acquiring a real-time vehicle speed, a vehicle structural state and a required deceleration of the target vehicle, and inquiring the sliding deceleration meter to obtain a sliding deceleration corresponding to the vehicle structural state and the real-time vehicle speed;

and if the required deceleration is smaller than the sliding deceleration, controlling the EBS of the target vehicle to perform braking.

7. The semitrailer adaptive cruise longitudinal control method according to claim 1, wherein proportional-integral control is performed on the engine execution torque based on the difference between the desired acceleration and the actual acceleration to obtain a feedback control torque, specifically comprising:

Calculating a difference between the actual acceleration and the expected acceleration, and inputting the difference to a PID controller of the target vehicle;

And receiving feedback control torque output by the PID controller.

8. A semitrailer adaptive cruise longitudinal control method according to claim 6, characterized in that the desired acceleration and the required deceleration are issued by an ACC control system of the target vehicle.

9. An adaptive cruise longitudinal control device for a semitrailer, comprising:

The acquisition module is used for acquiring the real-time speed, the vehicle structural state and the expected acceleration of the target vehicle, and calling a torque calibration database to obtain the expected torque corresponding to the real-time speed, the vehicle structural state and the expected acceleration; the torque calibration database comprises: a plurality of vehicle speed values in each vehicle structural state and a desired acceleration and a desired torque corresponding to each vehicle speed value;

the acquisition module is also used for acquiring the current actual acceleration of the target vehicle;

The PID control module is used for performing proportional integral control on the engine execution torque based on the difference value between the expected acceleration and the actual acceleration to obtain feedback control torque;

The torque processing module is used for obtaining the final request engine torque according to the expected torque and the feedback control torque;

the vehicle control module is used for controlling the target vehicle to run according to the request engine torque;

The torque calibration database is established based on three test working conditions, and the three test working conditions are respectively used for calibrating the corresponding torques of the sliding deceleration, the steady-speed torque and the maximum expected acceleration of the target vehicle in each vehicle structural state under each vehicle speed.