CN115503817A - Control system and method for switching power steering mode according to road conditions - Google Patents

Abstract

The control system and method for switching steering assist modes through road conditions relate to the technical field of vehicle steering mode switching by road surface information collection. The present invention aims at poor working conditions such as non-oil asphalt roads in towns and towns, and on the premise of ensuring safety. Control system and method, the control system includes: a road surface information collection module, an information processing module, a vehicle speed collection module, a steering wheel angle collection module, an electronic control module, an early warning module and a power steering module; the present invention directly obtains points on the road ahead based on laser radar Cloud data does not rely on the acceleration sensor and active suspension attached to the vehicle, and is not limited by objective factors such as light and night. This method collects the roughness information of the road ahead of the vehicle in real time, and can grasp the road conditions ahead in advance. Sufficient time is provided for the adjustment of the suspension and other mechanisms, and the steering assist mode is actively switched, thereby reducing the impact of uneven roads on the steering wheel and improving the driver's comfort experience.

Description

Control system and method for steering assist mode switching based on road conditions

technical field

The invention relates to the technical field of vehicle steering mode switching by road surface information collection, and in particular to a steering assist mode switching control system and method based on road surface conditions.

Background technique

With the development of electric vehicle technology, the field of intelligent driving assistance has gradually entered everyone's field of vision, focusing on the driver's driving experience and driving safety. Information feedback, which will cause bumps during driving on uneven roads, resulting in vertical vibration of the vehicle, is an important factor affecting the driver's driving experience and vehicle ride comfort and stability. Therefore, in order to better control the vehicle, improve the driver's For the driving experience, it is necessary to optimize the hand force on the uneven road in the direction of the vehicle, so as to reduce the impact of the road on the steering wheel and cause strong hand vibration.

Most of the existing systems at home and abroad are based on tires, electronically controlled suspension execution systems, etc. to respond and adjust to the pits and bumps on the road surface, but this device has hysteresis and does not improve the steering force. Therefore, the driver has already felt the vibration caused by the undulations of the road surface and the hand vibration caused by the impact of the steering wheel.

Therefore, to solve the above problems, it is necessary to obtain the uneven road ahead information in advance, and the recognition and steering assistance adjustment system that can work quickly, accurately, and around the clock is crucial to improving vehicle ride comfort, operability, and driver driving experience.

Contents of the invention

The purpose of the present invention is to provide a steering assist mode switching control system and method based on road conditions, aiming at poor working conditions such as non-asphalt roads in towns and towns, under the premise of ensuring safety, the point cloud of the road ahead can be directly obtained based on laser radar The data does not rely on the acceleration sensor and active suspension mechanism attached to the vehicle, and is not limited by objective factors such as light and night, and actively switches the power steering mode, thereby reducing the impact of uneven roads on the steering wheel and improving the driver's performance. comfort experience.

Steering assist mode switching control system based on road conditions, the control system includes: road information acquisition module, information processing module, vehicle speed acquisition module, steering wheel angle acquisition module, electronic control module, early warning module and steering assist module;

The road surface information collection module is used to collect the road conditions ahead;

The information processing module is used for data processing after receiving the road surface information ahead to obtain the elevation value of the road surface ahead;

The vehicle speed collection module is used to collect vehicle speed information;

The steering wheel angle acquisition module is used to acquire the steering wheel angle signal;

The electronic control module is used to receive the front road elevation value obtained by the information processing module, the vehicle speed information of the vehicle speed acquisition module and the steering wheel angle signal collected by the steering wheel angle acquisition module; The power assist module sends a steering mode switching signal;

The early warning module is used to receive the early warning signal sent by the electronic control module;

The power steering module is used to receive the steering mode switching signal sent by the electronic control module.

Further, the road surface information acquisition module is connected to the information processing module through the CAN bus, the information processing module, the vehicle speed acquisition module, the steering wheel angle acquisition module and the electronic control module are connected through the CAN, the electronic control module and the early warning module are connected through wires, and the electronic control The module and the power steering module are connected by CAN bus.

The present invention provides a control method for switching power steering mode through road conditions, the method is realized by the following steps:

S1. The road surface information collection module collects the road surface information ahead, the vehicle speed collection module collects the current vehicle speed, and the steering wheel angle collection module collects the current steering wheel angle signal;

S2. Carry out preprocessing of coordinate transformation and zero-point correction in the coordinates on the road surface information in front collected by S1, extract available point cloud data, and obtain the elevation value of the road surface ahead through analysis;

S3, according to the elevation value of the road ahead obtained by the analysis in S2, the current vehicle speed in step S1R, and the current steering wheel angle signal in S1, the steering column assist torque is analyzed and processed until the next moment;

S4. When the power steering torque of the steering column is greater than the current steering wheel torque at the next moment, the electronic control module sends an early warning signal to the early warning module, and sends a power steering mode switch to the power steering module, and the power steering module performs an action after the vehicle warning;

Further, the step S2 specifically includes the following steps:

S21, the calculation process of the elevation value is:

hi=hset-xo×sinαp-di×sin(αp+αd+αo)

In the formula, hset is the installation height of the lidar, xo is the horizontal distance from the center of the radar to the center of mass of the vehicle, αp is the pitch angle of the vehicle body when the car is running, αd is the pitch angle deviation of the radar installation, and αo is the radar light relative to itself The angle of , di is the straight-line distance from the radar to the road scanning point.

S22. Correct the elevation value, and the corrected elevation value is:

Hi=kj×hi(j=1,2,3); where, kj is the correction coefficient.

Further, the step S3 specifically includes the following steps:

S31. According to the sampling period, the elevation value obtained by the information processing module and the vehicle speed signal obtained by the vehicle speed acquisition module;

S32. Determine the input layer neuron vector O={O1, O2} of the three-layer BP neural network, wherein O1 is the elevation value, and O2 is the current vehicle speed;

S33. The input layer vector is mapped to a hidden layer, and the number of neurons in the hidden layer is n;

其中，o为输入层节点个数，p为输出层节点个数，q为调节常数，取值范围为1～10；Wherein, the number n of the hidden layer nodes satisfies:

Among them, o is the number of nodes in the input layer, p is the number of nodes in the output layer, q is an adjustment constant, and the value range is 1 to 10;

S34. Obtain the output layer vector P={P1}.

S35. Calculate the assist torque of the steering column as:

e=r*sinγ*cosp

In the formula, F ₀ is the lateral reaction force of the steering wheel, m is the total mass, a ₀ is the lateral acceleration, γ is the caster angle, L is the wheelbase, l ₁ is the distance from the center of the front wheel to the center of mass, e is the distance from the tire contact point to the kingpin, r the tire radius, μ ₁ is the positive transmission efficiency of the steering system, d is the diameter of the steering wheel, i _w is the transmission ratio of the steering system, and F _r1 is the steering force required by the steering wheel.

Beneficial effects of the present invention: the present invention directly acquires the point cloud data of the road ahead based on laser radar, does not rely on the acceleration sensor and active suspension mechanism attached to the vehicle, and is not limited by objective factors such as light and night, the system and The method collects the roughness information of the road in front of the vehicle in real time, which can grasp the road conditions ahead, provide sufficient time for the adjustment of the suspension and other mechanisms, and actively switch the power steering mode, thereby reducing the impact of the uneven road on the steering wheel and improving driving. occupant comfort experience.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic structural diagram of a steering assist mode switching control system provided by the present invention through road conditions;

Fig. 2 is a schematic diagram of the scanning mode of the laser radar provided by the present invention on the vehicle;

3 is a schematic diagram of the installation position of the laser radar provided by the present invention on the vehicle;

4 is a schematic diagram of the geometric relationship between the laser radar and the road surface provided by the present invention;

FIG. 5 is a schematic flowchart of an active steering and obstacle avoidance method based on lidar road surface information recognition provided by the present invention.

detailed description

This embodiment is described in conjunction with Fig. 1. The power steering mode switching control system is performed according to the road surface conditions. The system includes a road surface information collection module, an information processing module, a vehicle speed collection module, a steering wheel angle collection module, an electronic control module, an early warning module and a power steering module. The road surface information acquisition module is connected with the information processing module by the CAN bus, the information processing module, the vehicle speed acquisition module, the steering wheel angle acquisition module and the electronic control module are connected by the CAN, the electronic control module and the early warning module are connected by wires, and the electronic control module and the The power steering module is connected by CAN bus.

In this embodiment, the road surface information collection module is used to collect road surface information ahead and send it to the information processing module; the information processing module is used to receive point cloud information and perform preprocessing such as coordinate conversion and zero point correction to extract The point cloud data can be used to calculate the road elevation value and send it to the electronic control module; the vehicle speed acquisition module is used to collect the current vehicle speed signal and send it to the electronic control module; the steering wheel angle acquisition module is used to collect the current steering wheel angle signal and send it to the electronic control module. Send it to the electronic control module; the electronic control module is used to receive the elevation value of the road ahead, the current vehicle speed signal, and the steering wheel angle signal, and analyze and process the above signals through the built-in logic control algorithm, and then obtain the steering wheel at the next moment. The applied torque M is compared with the current actual torque N. If M>N or M<N, an early warning signal is sent to the early warning module, and a steering command signal is sent to the steering assist control module.

As shown in Figure 2, during the driving process of the vehicle, longitudinal scanning is performed on the road ahead in real time to obtain information about bumps or pits on the road. h _set is the installation height of the lidar.

As shown in Figure 3, the LUX4L four-line laser radar is used in the present invention, which is installed in the middle of the two headlights, at the same height as the headlights, to ensure that the road information ahead can be clearly scanned.

As shown in Figure 4, x _o is the horizontal distance from the radar center to the center of mass of the vehicle, α _p is the pitch angle of the vehicle body when the car is running, α _d is the pitch angle deviation of the radar installation, and α _o is the angle of the radar light relative to itself , d _i is the straight-line distance between the radar and the road scanning point, then the inclination angle a _i of the laser beam emitted by the radar relative to the forward direction can calculate the horizontal distance x _i and the road elevation value h _i of each scanning point on the road surface, where the road elevation Based on the road surface height h _o corresponding to the first point of scanning, the following formula is given:

α _i =α _p +α _d +α _o

x _i =d _i ×cosα _i =d _i ×cos(α _p +α _d +α _o )

h _i =h _o -d _i ×sinα _i =h _o -d _i ×sin(α _p +α _d +α _o )

Specific Embodiment 2. This embodiment is described in conjunction with FIGS. 2-5 , and the method for actively switching the steering assist mode based on lidar road surface information recognition, the steps of the method are as follows:

S1. The road surface information collection module collects the road surface information ahead, the vehicle speed collection module collects the current vehicle speed, and the steering wheel angle collection module collects the current steering wheel angle signal;

S2. Carry out preprocessing of coordinate transformation and zero-point correction in the coordinates on the road surface information in front collected by S1, extract available point cloud data, and obtain the elevation value of the road surface ahead through analysis;

S3, according to the elevation value of the front road surface obtained by S2 analysis, the current vehicle speed obtained by step S1 and the current steering wheel angle signal obtained by step S1, the steering column assist torque is analyzed and processed until the next moment;

S4. When the power steering torque of the steering column is greater than the current steering wheel torque at the next moment, the electronic control module sends an early warning signal to the early warning module, and sends a power steering mode switch to the power steering module, and the power steering module performs an action after the vehicle warning;

In this embodiment, the specific process of the step S2 is:

S21, the calculation process of the elevation value is:

hi＝h _set -xo×sinα _p -di×sin(α _p +α _d +αo)

In the formula, h _set is the installation height of the lidar, x _o is the horizontal distance from the center of the radar to the center of mass of the vehicle, α _p is the pitch angle of the vehicle body when the car is running, α _d is the pitch angle deviation of the radar installation, and αo is the radar light Relative to its own angle, d _i is the linear distance from the radar to the road surface scanning point.

S22. Correct the elevation value, and the corrected elevation value is:

Hi=kj×hi; where, kj is the correction coefficient, j=1,2,3.

In this embodiment, the specific process of step S3 is:

S31. According to the sampling period, obtain the vehicle speed signal through the elevation value obtained by the information processing module and the vehicle speed acquisition module;

S32. Determine the input layer neuron vector O={O1, O2} of the three-layer BP neural network, wherein O1 is the elevation value, and O2 is the current vehicle speed;

S33. The input layer vector is mapped to a hidden layer, and the number of neurons in the hidden layer is n;

其中，o为输入层节点个数，p为输出层节点个数，q为调节常数，取值范围为1～10；Wherein, the number n of the hidden layer nodes satisfies:

Among them, o is the number of nodes in the input layer, p is the number of nodes in the output layer, q is an adjustment constant, and the value range is 1 to 10;

S34. Obtain an output layer vector P={P1}.

S35. Calculate the assist torque of the steering column as:

e=r*sinγ*cos p

In the formula, F ₀ is the lateral reaction force of the steering wheel, m is the total mass, a ₀ is the lateral acceleration, γ is the caster angle, L is the wheelbase, l ₁ is the distance from the center of the front wheel to the center of mass, e is the distance from the tire contact point to the kingpin, r the tire radius, μ ₁ is the positive transmission efficiency of the steering system, d is the diameter of the steering wheel, i _w is the transmission ratio of the steering system, and F _r1 is the steering force required by the steering wheel.

Specific Embodiment 3. This embodiment is an embodiment of the method for actively switching the steering assist mode based on lidar road surface information recognition described in Embodiment 2: the method is as follows (taking left turn as an example);

Step 1: Obtain the road surface information in front of the vehicle;

Step 2: Carry out preprocessing such as coordinate conversion and zero point correction on the road surface information to extract the available point cloud data, and obtain the elevation value H of the road ahead through analysis;

Step 3: Collect the current vehicle speed signal v and the steering wheel angle signal α.

Step 4: Send the front road elevation value H, the current vehicle speed signal v, and the steering wheel angle signal α to the vehicle controller, analyze and process the above three signals through the built-in logic control algorithm, and then obtain the steering wheel steering at the next moment assist value M, and compare it with the current steering assist value N;

Step 5: If M>N or M<N, perform the following steps;

Step 6: Send an early warning signal to the early warning module, and send a power steering switching command to the power steering control module;

Step 7: After the vehicle is alerted, the steering assist module executes the command to complete the assist mode switching.

The control method for switching the steering assist mode according to the road surface conditions described in this embodiment can effectively improve the safety, comfort and intelligence of driving a passenger car.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (5)

1. A steering assist mode switching control system based on road surface conditions, the control system comprising: the system comprises a road surface information acquisition module, an information processing module, a vehicle speed acquisition module, a steering wheel corner acquisition module, an electronic control module, an early warning module and a steering power-assisted module; the method is characterized in that:

the road surface information acquisition module is used for acquiring the road condition in front;

the information processing module is used for receiving the front road surface information and then performing data processing to obtain a front road surface elevation value;

the vehicle speed acquisition module is used for acquiring vehicle speed information;

the steering wheel corner acquisition module is used for acquiring steering wheel corner signals;

the electronic control module is used for receiving the front road surface elevation value obtained by the information processing module, the vehicle speed information of the vehicle speed acquisition module and the steering wheel corner signal acquired by the steering wheel corner acquisition module; whether an early warning signal is sent to the early warning module and a steering mode switching signal is sent to the power steering module is judged;

the early warning module is used for receiving an early warning signal sent by the electronic control module;

and the steering power-assisted module is used for receiving a steering mode switching signal sent by the electronic control module.

2. The system according to claim 1, characterized in that: the road surface information acquisition module is connected with the information processing module through a CAN bus, the information processing module, the vehicle speed acquisition module and the steering wheel corner acquisition module are connected with the electronic control module through the CAN, the electronic control module is connected with the early warning module through an electric wire, and the electronic control module is connected with the steering power-assisted module through the CAN bus.

3. A steering power-assisted mode switching control method through road surface conditions is characterized in that: the method is realized by the system for controlling the switching of the steering power-assisted mode according to the road surface condition as claimed in claim 1 or 2, and the method comprises the following specific processes:

s1, a road surface information acquisition module acquires front road surface information, a vehicle speed acquisition module acquires a current vehicle speed, and a steering wheel corner acquisition module acquires a current steering wheel corner signal;

s2, preprocessing coordinate conversion and zero point correction in coordinates is carried out on the front road surface information collected in the S1, available point cloud data are extracted, and a front road surface elevation value is obtained through analysis;

s3, analyzing and processing the power-assisted moment of the steering column at the next moment according to the front road surface elevation value obtained by analyzing in the S2, the current vehicle speed obtained in the step S1 and the current steering wheel corner signal obtained in the step S1;

and S4, when the power-assisted torque of the steering column at the next moment is larger than the current steering wheel turning angle torque, the electronic control module sends an early warning signal to the early warning module, and sends steering power-assisted mode switching to the steering power-assisted module, and the steering power-assisted module performs action after the vehicle gives an early warning.

4. The steering assist mode switching control method according to claim 3, characterized in that: the specific process of the step S2 is as follows:

s21, the elevation value calculation process comprises the following steps:

hi＝h _set -x _o ×sinα _p -di×sin(α _p +α _d +α _o )

in the formula, h _set For the laser radar mounting height, x _o Horizontal distance, α, from radar centre to vehicle centre of mass _p Is the pitch angle of the vehicle body, alpha, during running _d Deviation of pitch angle, alpha, for radar installations _o Angle of radar ray relative to itself, d _i The linear distance of the radar from the road surface scanning point is obtained.

S22, correcting the elevation value, wherein the corrected elevation value is as follows:

hi = kj × Hi; where kj is a correction coefficient, and j =1,2,3.

5. The steering assist mode switching control method according to claim 3, characterized in that: the specific process of the step S3 is as follows:

s31, according to a sampling period, obtaining a vehicle speed signal through an elevation value obtained by the information processing module and the vehicle speed acquisition module;

s32, determining an input layer neuron vector O = { O1, O2} of the three-layer BP neural network, wherein O1 is an elevation value, and O2 is the current vehicle speed;

s33, mapping the vector of the input layer to a hidden layer, wherein n neurons of the hidden layer are provided;

wherein the number n of hidden layer nodes satisfies:

wherein o is the number of nodes of the input layer, and p isThe number of output layer nodes, q is an adjusting constant, and the value range is 1-10;

s34, obtaining an output layer vector P = { P1};

s35, calculating the power-assisted moment of the steering column as follows:

e＝r*sinγ*cosp

in the formula, F ₀ Is the lateral reaction force of the steering wheel, m is the total mass, a ₀ Is lateral acceleration, gamma is caster angle of the kingpin, L is wheelbase, L ₁ Is the distance from the center of the front wheel to the center of mass, e is the distance from the ground contact point of the tire to the kingpin, r is the tire radius, mu ₁ For positive steering system transmission efficiency, d is the steering wheel diameter, i _w For steering gear ratio, F _r1 The steering force required for the steering wheel.

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