CN107150682B - A kind of lane holding auxiliary system - Google Patents

Abstract

The present invention relates to a lane keeping assist system, comprising: a sensing module, used to collect lane information and vehicle information; a control module, connected to the sensing module and a vehicle controller respectively, used to calculate the lane keeping assisting torque according to the received information, And superimposed with the driver's real steering torque to form a virtual driver's steering torque; the execution module is connected to the control module and is used to respond to the virtual driver's steering torque. Compared with the prior art, the present invention superimposes the lane keeping assist torque and the driver's real steering torque to obtain a virtual driver's steering torque, which replaces the driver's real steering torque originally measured from the steering torque sensor, thereby realizing the lane keeping function. The utility model has the advantages of easy hardware realization, convenient modification, low cost and the like.

Description

A lane keeping assist system

technical field

The invention belongs to the technical field of automobiles and relates to an advanced driver assistance system, in particular to a lane keeping assistance system.

Background technique

Nowadays, there are countless traffic accidents caused by driver factors every year, so smart cars and advanced driver assistance systems have become current research and industry hotspots, and lane keeping assistance systems, as one of the horizontal driver assistance systems, can effectively Prevent the vehicle from deviating from the lane when driving at high speed, thus effectively preventing the occurrence of traffic accidents caused by lane departure.

In a typical lane keeping assist system, when the vehicle reaches a preset speed and is about to deviate from the lane, and the driver does not turn on the turn signal, the lane keeping assist system will actively intervene in the heading control of the vehicle. It is more common to apply a braking force on one side of the wheel, or to apply a steering force on the steering system. With the popularization of the electric power steering system, by modifying the power assist strategy in the electric power steering system and adding the control strategy of lane keeping, a steering force is stimulated on the motor to correct the vehicle heading when the vehicle gradually deviates from the lane. The method facilitates realizing the function of lane keeping assistance.

However, in a typical lane keeping assist device, when the vehicle is about to deviate from the lane, the controller directly sends a torque command to the booster motor in the electric power steering system. With the high integration of the system, the steering system supplier usually provides the steering system assembly directly to the OEM, and the power assist strategy and the torque command interface of the motor are usually not open to the OEM, or the torque control interface has not been reserved in advance. Therefore, if the OEM wants to develop a lane keeping assist system based on the original electric power assist system, without the support of the steering system supplier, it cannot directly send a torque command to the booster motor, thereby failing to realize the lane keeping assist function. If the controller of the electric power steering system is developed by itself, replacing the existing controller of the original car, or adding an additional motor for the lane keeping assist function, although the lane keeping assist function can be realized, the changes to the original system are too large, The integrity and reliability of the original steering system function will be difficult to guarantee, and the cost will be high.

Therefore, it is of great significance to develop a lane keeping system that is easy to refit and can ensure the reliable operation of the original steering system.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a lane keeping assist system in order to overcome the above-mentioned defects in the prior art. The lane keeping assist torque and the driver's real steering torque are superimposed to obtain a virtual driver's steering torque, which replaces the steering torque measured by the steering torque sensor. The driver's real steering torque is obtained, so as to realize the lane keeping function.

The purpose of the present invention can be achieved through the following technical solutions:

A lane keeping assist system comprising:

Perception module, used to collect lane information and vehicle information;

The control module is connected to the perception module and the vehicle controller respectively, and is used to calculate the lane keeping assist torque according to the received information, and superimpose it with the driver's real steering torque to form a virtual driver's steering torque;

The execution module is connected with the control module, and is used for responding to the virtual driver's steering torque.

The perception module includes a lane line recognition sensor for collecting vehicle position information and road information, a corner sensor for collecting the current steering wheel angle, and a steering torque sensor for collecting the driver's real steering torque;

The vehicle position information includes the lateral offset and yaw angle of the current vehicle relative to the lane, and the road information includes the curvature of the road ahead.

The control module includes:

A state decision unit, configured to determine the working state of the lane keeping assist system according to the vehicle position information, road information, the driver's real steering torque and the switch signal sent from the human-computer interaction device, and generate a corresponding assist torque suppression coefficient α;

The automatic lane following control unit is used to calculate the virtual lane following driver's torque T′ _h according to the vehicle position information, road information, current steering wheel angle and vehicle dynamics information sent from the vehicle controller;

The output torque decision unit obtains the lane keeping assist torque T _lka according to the working state and the virtual lane following driver torque, T _lka =T′ _h *α.

The specific process of obtaining the auxiliary torque suppression coefficient α by the state decision-making unit is as follows:

1) Judging whether the lane keeping assist system is off according to the switch signal, if yes, then the lane keeping assist system enters the off state, the assist torque suppression coefficient α=0, return to step 1), if not, go to step 2);

2) According to the collected information of the lane line recognition sensor, it is judged whether the lane line is effectively detected, if yes, go to step 3), if not, the lane keeping assist system enters the off state, the auxiliary torque suppression coefficient α=0, return to step 1) ;

3) According to the vehicle position information and road information collected by the lane line recognition sensor, calculate the time when the front wheel on the side close to the lane line is pressed against the lane line, and judge whether the time is greater than the first threshold. If so, the lane keeping assist system In the standby state, the auxiliary torque suppression coefficient α=0, return to step 1), if not, go to step 4);

4) Determine whether the driver's real steering torque collected by the steering torque sensor is greater than the second threshold, if so, the lane keeping assist system is in a standby state, the auxiliary torque suppression coefficient α=0, return to step 1), if not, then go to step 5 );

5) The lane keeping assist system is in a normal working state, the assist torque suppression coefficient α=1, and step 6) is executed at the same time;

6) Determine whether the lateral offset of the current vehicle relative to the lane is greater than the third threshold, if yes, go to step 1), if not, the lane keeping assist system is in standby state, the auxiliary torque suppression coefficient α=0, return to step 1 ).

The lane automatic following control unit responds when the assist torque suppression coefficient α=1.

The specific process of calculating the virtual lane following driver's moment T′ _h by the automatic lane following control unit is as follows:

Calculate the target angle θ′ needed to keep the lane:

θ′=k _y *y+k _Ψ *Ψ+k _R *R

Among them, y is the lateral offset of the current vehicle relative to the lane, Ψ is the yaw angle, R is the curvature of the road ahead, and _ky , k _Ψ , k _R are proportional coefficients;

Making a difference between the target rotation angle θ' and the current steering wheel rotation angle θ measured by the rotation sensor to obtain the rotation angle error e;

Calculate virtual lane following driver moment T′ _h :

Among them, k _p , _ki , and k _d are proportional, integral, and differential coefficients, respectively.

The control parameters adopted by the lane automatic following control unit are obtained by looking up a table according to the vehicle speed information in the vehicle dynamics information.

The output torque decision unit includes a slope limiting subunit for limiting the rate of change of the auxiliary torque suppression coefficient.

The output torque decision-making unit includes a selection sub-unit and a memory sub-unit for linearly changing the lane keeping assist torque.

The executive module includes a connected electric power steering system controller and a booster motor, and the electric power steering system controller is connected with the control module.

Compared with the prior art, the present invention superimposes the lane keeping assist torque and the driver's real steering torque to obtain a virtual driver's steering torque, which replaces the driver's real steering torque originally measured from the steering torque sensor, thereby realizing the lane keeping function. Has the following advantages:

1) There is no need for the electric power steering system controller of the original car to open the torque control command interface of the power assist motor, and the hardware is easy to implement, easy to modify, and low in cost;

2) There is no need to change the electric power steering system controller and power assist motor of the original vehicle, which ensures the integrity and reliability of the original steering system functions;

3) It can realize the function of the complete lane keeping assist system, which is convenient for the secondary development and expansion of the function.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a schematic diagram of the control strategy of the lane keeping auxiliary controller of the present invention;

Fig. 3 is a schematic diagram of the lane keeping auxiliary controller of the present invention;

Fig. 4 is a schematic diagram of the workflow of the state decision-making unit of the present invention;

Fig. 5 is a schematic diagram of the principle of the automatic lane following control unit of the present invention;

Fig. 6 is a schematic diagram of the principle of the output torque decision-making unit of the present invention;

Fig. 7 is a schematic diagram of the result of lane keeping assistance in the present invention;

Fig. 8 is a schematic diagram of the result of the corner tracking control of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

As shown in Figure 1, the lane keeping assist system includes a perception module, a control module and an execution module. The perception module is used to collect lane information and vehicle information; The device is used to calculate the lane keeping assist torque according to the received information, and superimpose it with the driver's real steering torque to form a virtual driver's steering torque; the execution module is connected to the control module, and is used to respond to the virtual driver's steering torque. The control algorithm runs in the lane keeping assist controller, and the calculated lane keeping assist torque is superimposed with the driver's original input torque to obtain a virtual driver's steering torque, which replaces the real driver's input torque originally measured from the torque sensor, thereby realizing Lane keeping function. The execution modules all use the original modules of the vehicle to ensure the integrity and reliability of the original vehicle system functions.

1. Hardware connection

In a traditional electric power steering device, the electric power steering controller calculates the motor assist torque according to the preset power assist characteristic according to the driver input steering torque measured by the steering torque sensor in the steering system, and Send the command to the motor drive module to achieve the boost effect.

In order to realize the lane keeping assist function, the lane keeping assist torque is added to the output signal of the steering torque sensor, so that the electric booster motor responds to the additional lane keeping assist torque. The wiring harness between the steering torque sensor and the electric power steering system controller is divided into a power supply wiring harness and a signal wiring harness. In order to ensure the reliability of the power supply function of the torque sensor, it is not necessary to cut off the original power supply harness, only the signal harness is cut off and connected to the I/O port of the controller.

The control strategy block diagram of the lane keeping assist controller of the present application is shown in Figure 2. According to the driver's real steering torque, vehicle position information, road information, current steering wheel angle and vehicle dynamics information, the lane keeping assist torque is calculated, and The driver's real steering torque is superimposed to obtain the virtual driver's steering torque, which replaces the real driver's steering torque output by the original steering torque sensor and is sent to the electric power steering system controller to realize the lane keeping function.

2. Perception module

The perception module includes a lane line recognition sensor that collects vehicle position information and road information, a corner sensor that collects the current steering wheel angle, and a steering torque sensor that collects the driver's real steering torque. The vehicle position information includes the lateral offset and yaw angle of the current vehicle relative to the lane, and the road information includes the curvature of the road ahead.

3. Control module

The system block diagram of the control module is shown in Figure 3, including the state decision-making unit, the automatic lane following control unit and the output torque decision-making unit.

(1) State decision unit

The state decision unit is used to control the working state of the lane keeping assist system according to the vehicle position information, road information, the driver's real steering torque and the switch signal sent from the human-computer interaction device, and generate the corresponding assist torque suppression coefficient α. The input of the state decision-making unit includes information such as the lateral position of the current vehicle relative to the lane measured by the lane line recognition sensor, yaw angle, and the curvature of the road ahead, as well as the driver's input torque measured by the steering torque sensor, and the output is auxiliary torque suppression coefficient.

The workflow of the state decision-making unit is shown in Figure 4, specifically:

The judging part 01 receives the switch signal of the lane keeping assist system from the human-computer interaction device. If the driver turns off the lane keeping assist system, the system enters the off state, and the assist torque suppression coefficient α is equal to 0, and then returns to the judging part 01 for the next step. Judging, if the lane keeping assist system is turned on, the judging part 02 is executed. In the judging part 02, if the lane line recognition sensor judges that the lane line cannot be effectively detected at present, the system will also enter the shutdown state; otherwise, it will enter the judging part 03. The judging part 03, according to the position information of the vehicle relative to the current lane measured by the lane line recognition sensor, calculates the time when the front wheel on the side close to the lane line is pressed to the lane line of the current lane, and compares whether the time is greater than the first threshold, If the time from the vehicle to the lane line of the current lane is greater than the first threshold, it is considered that the vehicle has no tendency to deviate from the lane, the lane keeping assist system is in a standby state, and the auxiliary torque suppression coefficient α is equal to 0, and then returns to the judgment part 01 Make the next judgment, otherwise enter the judgment part 04. The judging part 04, according to the driver's steering torque information measured by the steering torque sensor, compares whether the driver's input torque is greater than the second threshold, and if the driver's input torque is greater than the second threshold, then it is judged that the driver is actively performing Steering behavior, the lane keeping assist system is in the standby state, and the assist torque suppression coefficient α is equal to 0. Otherwise, the lane keeping assist system is in a normal working state, and the assist torque suppression coefficient α is equal to 1. When the lane keeping assist system is turned on, the judgment part 05 is executed. Judging part 05, according to the information of the lane line recognition sensor, compares whether the lateral offset of the vehicle relative to the center line of the lane is greater than the third threshold, and if the lateral offset is smaller than the third threshold at this time, it is considered that the vehicle has returned to the center of the lane , the lane keeping system is in the standby state, and the auxiliary torque suppression coefficient α is equal to 0, otherwise, the system continues to be in the normal working state, and returns to the judgment part 01.

(2) Lane automatic following control unit

The automatic lane-following control unit is used to calculate the virtual lane-following driver's torque T′ _h according to vehicle position information, road information, current steering wheel angle and vehicle dynamics information sent from the vehicle controller. The input of the automatic lane following control unit includes information such as the current lateral position of the vehicle relative to the lane measured by the lane line recognition sensor, the yaw angle, and the curvature of the road ahead, the current steering wheel angle measured by the rotation angle sensor, and the current steering wheel angle measured by the vehicle controller. The sent vehicle speed information is output as virtual lane following driver torque.

The automatic lane following control unit can respond only when the assist torque suppression coefficient α=1.

The schematic diagram of the automatic lane following control unit is shown in Figure 5, which can be divided into a lateral position controller and a steering wheel angle controller. The lateral position controller calculates the target required for maintaining the lane according to the road information and vehicle position information obtained by the lane line recognition module, including: the lateral offset y of the vehicle relative to the current lane, the heading angle Ψ, and the curvature R of the road ahead Rotation angle θ′, the lateral position controller can be designed according to the performance index requirements of the vehicle pose closed-loop system taking into account the road curvature, and a proportional controller can also be used. The control algorithm is:

θ′=k _y *y+k _Ψ *Ψ+k _R *R

The difference between the target rotation angle θ′ calculated by the lateral position controller and the actual steering wheel rotation angle θ measured by the rotation angle sensor is obtained to obtain the rotation angle error e, and the virtual lane following driver torque T′ _h is calculated. The steering wheel angle controller can be designed according to the performance index requirements of the angle closed-loop system, or a proportional-integral-derivative controller can be used, and its control algorithm is:

At the same time, according to the vehicle speed information sent by the vehicle controller, the control parameters of the lane automatic following control module corresponding to the preset vehicle speeds are obtained by looking up the table, so as to ensure that the system can effectively realize the ideal vehicle speed at all vehicle speeds. lane keeping function.

(3) Output torque decision unit

The output torque decision unit obtains the lane keeping assist torque T _lka according to the working state and the virtual lane following driver torque, T _lka = T′ _h *α. The input of the output torque decision unit includes the auxiliary torque suppression coefficient obtained by the state decision unit and the virtual lane following driver torque obtained by the automatic lane following control unit, and the output is the lane keeping auxiliary torque. When the auxiliary torque suppression coefficient α=1, the virtual driver steering torque T _lka output by the lane keeping system is the virtual lane following driver torque T′ _h ; when the auxiliary torque suppression coefficient α=0, the virtual driver torque T′ h output by the lane keeping system The driver's steering torque T _lka is equal to zero.

As shown in Figure 6, since the lane keeping assist system exits from normal operation to the standby or off state, it is usually caused by the driver’s active steering. At this time, the driver will hold the steering wheel tightly, so it is guaranteed to During the standby or off state, it is particularly important that the lane keeping assist torque exit smoothly, so as to avoid the driver's steering feeling discomfort or even driving panic. In order to achieve the above purpose, the slope limiting subunit Rate_limiter is used to limit the rate of change of the auxiliary torque suppression coefficient α from being too large.

At the same time, because during the process of the auxiliary torque suppression coefficient α decreasing from 1 to 0, the virtual lane following driver’s torque T′ _h may fluctuate due to the change of the vehicle position, so that the output virtual driver’s steering torque T _lka The changes are non-linear, resulting in a bad driver feel. Therefore, the present invention combines the selection subunit and the memory subunit shown in FIG. 6 to ensure that the output virtual driver's steering torque T _lka changes linearly during the state switching process. The role of the selection subunit Switch and the memory subunit Memory is: when the auxiliary torque suppression coefficient α decreases from 1 to 0, ensure that the virtual lane-following driver torque T′ _h remains unchanged, thus ensuring the final output of the virtual driver The change of the steering torque T _lka is linear when the state is switched, so as to ensure the driver's steering feel comfortable.

4. Algorithm verification

Fig. 7 is a schematic diagram of lane keeping assistance results at various vehicle speeds. The solid line and dotted line shown in the figure are the lateral offset of the vehicle relative to the lane and the working status of the lane keeping assist system at the speed of 120kph and 80kph respectively. A high level indicates that the system is in normal working condition, and a low level indicates that the system is in standby state.

Fig. 8 is a schematic diagram of the corner tracking control results at various vehicle speeds. The solid line shown in the figure is the actual steering wheel angle. The dotted line shown in the figure is the target corner output by the lateral position controller in the automatic lane following control module. The dotted line shown in the figure is the working state of the lane keeping assist system. A high level indicates that the system is in a normal working state, and a low level indicates that the system is in a standby state.

The results show that at two speeds of 80kph and 120kph, the system can turn on the assistance when the vehicle is about to deviate from the lane, the actual steering wheel angle can track the target angle better, and at the same time can effectively correct the vehicle to return to the center.

The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make many modifications and changes according to the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall be within the scope of protection defined by the claims.

Claims (8)

1. a kind of lane keeps auxiliary system characterized by comprising

Sensing module, for acquiring lane information and information of vehicles；

Control module is separately connected sensing module and entire car controller, keeps auxiliary for calculating lane according to the information received Power-assisted square, and be superimposed with the true steering moment of driver, form Virtual drivers steering moment；

Execution module, link control module, for responding the Virtual drivers steering moment；

The sensing module includes the Lane detection sensor for acquiring vehicle position information and road information, acquires and work as front direction The rotary angle transmitter of disk corner and the steering torque sensor for acquiring the true steering moment of driver；

The vehicle position information includes transversal displacement and yaw angle of the current vehicle relative to lane, the road information packet Include road ahead curvature；

The control module includes:

State decision package, for according to vehicle position information, road information, the true steering moment of driver and from man-machine friendship The switching signal that mutual device is sent determines that the lane keeps the working condition of auxiliary system, and generates corresponding auxiliary torque suppression Factor alpha processed；

The automatic model- following control unit in lane, for according to vehicle position information, road information, current steering wheel angle and from whole The Full Vehicle Dynamics information that vehicle controller is sent calculates virtual lane and follows driver's torque T '_h；

Output torque decision package follows driver's torque to obtain lane and keeps auxiliary according to the working condition and virtual lane Torque T_lka, T_lka=T '_h*α。

2. lane according to claim 1 keeps auxiliary system, which is characterized in that the state decision package obtains auxiliary The detailed process of torque rejection coefficient α are as follows:

1) judge that lane keeps whether auxiliary system closes according to switching signal, if so, lane keeps auxiliary system to enter pass Closed state, auxiliary torque rejection coefficient α=0, return step 1), if it is not, then going to step 2)；

2) judge whether effectively to detect lane line according to the acquisition information of Lane detection sensor, if so, go to step 3), If it is not, then lane keeps auxiliary system to enter closed state, auxiliary torque rejection coefficient α=0, return step 1)；

3) it is calculated before lane line side according to the vehicle position information of Lane detection sensor acquisition and road information Wheelspan tripping judges whether the time is greater than first threshold to the time of the lane line, if so, lane keeps auxiliary system It is in standby, auxiliary torque rejection coefficient α=0, return step 1), if it is not, then going to step 4)；

4) judge whether the true steering moment of driver of steering torque sensor acquisition is greater than second threshold, if so, lane Auxiliary system is kept to be in standby, auxiliary torque rejection coefficient α=0, return step 1), if it is not, then going to step 5)；

5) lane keeps auxiliary system to be in normal operating conditions, and auxiliary torque rejection coefficient α=1 is performed simultaneously step 6)；

6) judge whether current vehicle is greater than third threshold value relative to the transversal displacement in lane, if so, go to step 1), if No, then lane keeps auxiliary system to be in standby, auxiliary torque rejection coefficient α=0, return step 1).

3. lane according to claim 1 keeps auxiliary system, which is characterized in that the automatic model- following control unit in lane It is responded in the auxiliary torque rejection coefficient α=1.

4. lane according to claim 1 keeps auxiliary system, which is characterized in that the automatic model- following control unit in lane It calculates virtual lane and follows driver's torque T '_hDetailed process are as follows:

Calculate target rotation angle θ ' required for keeping lane:

θ '=k_y*y+k_Ψ*Ψ+k_R*R

Wherein, y is transversal displacement of the current vehicle relative to lane, and Ψ is yaw angle, and R is road ahead curvature, k_y、k_Ψ、k_R For ratio control parameter；

It is poor that the current steering wheel angle θ that the target rotation angle θ ' and rotary angle transmitter are measured makees, and obtains angular errors e；

It calculates virtual lane and follows driver's torque T '_h:

Wherein, k_p、k_i、k_dFor ratio, integral, differential control parameter.

5. lane according to claim 4 keeps auxiliary system, which is characterized in that the automatic model- following control unit in lane The control parameter of use carries out acquisition of tabling look-up according to the vehicle speed information in Full Vehicle Dynamics information.

6. lane according to claim 1 keeps auxiliary system, which is characterized in that the output torque decision package includes Slope for limiting auxiliary torque rejection coefficient change rate limits subelement.

7. lane according to claim 1 keeps auxiliary system, which is characterized in that the output torque decision package includes Selection subelement and memory subelement for making lane that auxiliary torque be kept to change linearly.

8. lane according to claim 1 keeps auxiliary system, which is characterized in that the execution module includes being connected Electric booster steering system controller and assist motor, the electric booster steering system controller are connect with control module.