CN114312765B - A longitudinal active collision avoidance control system and method - Google Patents

Abstract

The invention discloses a longitudinal active anti-collision control system and a method, and the longitudinal active anti-collision control system comprises an environment and obstacle detection system, a chassis anti-collision control system, a wheel independent drive-by-wire system and a wheel independent drive-by-wire brake system, wherein the chassis anti-collision control system comprises a front-end collision protection system and a rear-end collision protection system; the wheel independent brake-by-wire system comprises a vehicle body stabilizing module and a brake delay compensation module, wherein the vehicle body stabilizing module is used for ensuring the stability of a vehicle, and the brake delay compensation module is used for compensating brake delay caused by brake execution action delay and communication delay. The system completes independent braking and independent driving operation commands of the independent wheels by using corresponding control strategies according to the external environment and the obstacle information, and guarantees the stability and safety of the vehicle in the running process.

Description

A longitudinal active collision avoidance control system and method

technical field

The invention relates to a longitudinal active anti-collision control system and method.

Background technique

With the rapid development of science and technology, the logistics and transportation industry is also developing in the direction of intelligence and networking. Under the wave of intelligence in the automotive industry, the improvement and development of the vehicle's wire-controlled chassis shows a rapid growth trend. With the increasing annual production of automobiles, the social problems caused by them are also becoming more and more serious, mainly involving problems such as large energy consumption, traffic congestion, high casualty rate of vehicle traffic accidents, and environmental pollution. Property safety has caused huge damage. The drive-by-wire chassis is the basis for various intelligent transformation and intelligent manipulation of vehicles. Under the combined effect of policies and the market, the improvement and further research on the drive-by-wire chassis has become the general trend.

Vehicle rear-end collision is the main cause of vehicle traffic accidents. Compared with the traditional chassis, the wire-controlled chassis eliminates the error of some actuators and provides the possibility for unmanned driving. The control execution of the drive-by-wire chassis is mainly based on the brake-by-wire, steering-by-wire and drive-by-wire drive of the vehicle chassis. Most rear-end collision accidents occur in longitudinal driving, and the active anti-collision control-by-wire chassis is designed for the rear-end collision when the longitudinal vehicle is driving. becomes necessary.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a longitudinal active anti-collision control system and method. The system uses corresponding control strategies according to the external environment and obstacle information to complete the independent braking and independent driving operation instructions of independent wheels to ensure the driving process of the vehicle. stability and security.

In order to realize the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is realized through the following technical solutions:

A longitudinal active anti-collision control system, including an environment and obstacle detection system, the environment and obstacle detection system is used to detect and collect environmental information and information on the position and motion status of obstacles on the front, rear, left, and right sides of the vehicle, and also includes chassis anti-collision system. A crash control system, a wheel independent drive-by-wire system and a wheel-independent brake-by-wire system, the chassis anti-collision control system includes a front-end collision protection system and a rear-end collision protection system, and the wheel-independent drive-by-wire system is used for driving the vehicle. Each wheel applies an independent driving force, and the wheel-independent brake-by-wire system is used to apply an independent braking force to each wheel of the vehicle. The braking force and driving force enable the vehicle to achieve front-end collision protection and rear-end collision protection; the wheel-independent brake-by-wire system includes a body stability module and a braking delay compensation module, the body stability module is used to ensure vehicle stability, and the braking The motion delay compensation module is used to compensate the brake delay caused by the brake execution delay and communication delay.

Preferably, it also includes a vehicle-to-vehicle communication system and a cloud communication system: the vehicle-to-vehicle communication system is used for information interaction between the wire-controlled chassis model vehicles, and the information interaction between the wire-controlled chassis type vehicles and other types of vehicles; the cloud communication system The system is used to record the environment of vehicles with chassis-by-wire vehicles and the environmental information data collected by the obstacle detection system, and transmit it to vehicles with non-wire-controlled chassis models. The cloud communication system also includes an information integration unit A, which integrates the information received by the cloud communication system, the obstacle information detected by the environment and the obstacle detection system, and the The interactive information of the vehicle-to-vehicle communication system is integrated.

Preferably, the environment and obstacle detection system includes an intelligent surround view sensor system, a wheel center relative height measuring instrument, an information integration unit B and a flatness information correction unit:

The intelligent surround view sensor system includes a mechanical lidar on the top of the vehicle, a solid-state lidar on the front of the vehicle, a binocular camera at the intersection of the top of the vehicle and the front, and a monocular camera at the rear of the vehicle;

The information integration unit B integrates the information collected by the mechanical laser radar and the binocular camera with the vehicle interaction information collected by the vehicle-to-vehicle communication system and the cloud communication system to accurately determine the status of obstacles and surrounding vehicles;

The flatness information correction unit corrects the flatness information of the surrounding road where the vehicle is traveling, which is collected by the solid-state lidar and the wheel center relative height measuring instrument.

Preferably, the chassis anti-collision control system is used to control a three-axle six-wheel vehicle, the wheel independent wire-controlled drive system is a six-wheel independent wire-controlled drive system, the six wheels are all driving wheels, and each driving wheel includes a driving mode, a Three working modes: dynamic mode and empty mode;

The wheel independent brake-by-wire system is a six-wheel independent brake-by-wire system, and the vehicle body stability module and the brake delay compensation module are used to ensure the vehicle's own stability and non-delay braking during braking.

Preferably, the driving wheels of the first axle at the front end of the vehicle and the third axle at the rear end of the vehicle adopt the wheel-side drive mode, the driving wheel of the second axle in the middle of the vehicle adopts the in-wheel motor drive mode, and the first axle at the front end of the vehicle and the third axle at the rear end of the vehicle adopt the in-wheel motor drive mode. The three-axle adopts electro-hydraulic coupling braking, and the second axis in the middle of the vehicle adopts electro-mechanical braking.

Preferably, when the second axle is in the emptying mode and only the wheel brakes of the first axle and the third axle are working, the wheel cylinder pressure values of the four wheel brakes of the first axle and the third axle are respectively:

In the formula, p ₁ , p ₂ , p ₅ , and p ₆ are the braking pressures of the left and right wheels of the first axis and the left and right wheels of the third axis, respectively, in MPa; F _Z1 , F _Z2 , F _Z5 , and F _Z6 respectively is the ground vertical force of the left and right wheels of the first axis and the left and right wheels of the third axis, in N; R _w1 and R _w3 are the radii of the wheels on the first and third axes, respectively, in meters; K _b is the braking pressure coefficient, which is the ratio of the wheel braking torque to the wheel cylinder pressure; ΔM _Z is the expected yaw moment of the vehicle, in Nm; B ₁ is the distance from the center of the left and right wheels of the first axis to the axle center, B ₃ is the distance from the center of the left and right wheels of the third axis to the axle center, the unit is meters; δ ₁ , δ ₂ , δ ₅ , δ ₆ are the rotation angles of the left and right wheels of the first axis and the left and right wheels of the third axis, the unit is rad .

Preferably, the compensation wheel cylinder pressure value of the brake delay compensation module is:

In the formula, p _com is the compensation wheel cylinder pressure value, t ₁ is the communication delay time, t ₂ ' is the time taken for the brake clearance to decrease, t ₂ '' is the time taken for the brake to be gradually pressed to a stable state, and the time after the brake starts to work. During the time period of t ₁ +t ₂ '+t ₂ ”/2, the value of p _pro is 30%-80% of the maximum wheel cylinder pressure value, the unit is MPa, and the value of p _pro depends on the chassis collision avoidance control system. Brake deceleration value, p(t) is the pressure value of the brake wheel cylinder at time t, the unit is MPa.

Preferably, the correction formula of the flatness information correction unit is:

In the formula, h _n,i is the corrected relative height of the i-th low obstacle on the uneven road around the vehicle; h' _n,i and h'n _,i are measured by solid-state lidar detection and wheel center relative height measuring instrument, respectively. The relative height of the low obstacle on the ith uneven road around the vehicle, in meters; vx _is the longitudinal speed of the vehicle, in m/s; k _vx is the longitudinal speed influence factor, in m/s.

Preferably, the obstacle information after information integration by the information integration unit B is:

In the formula, x _cj , y _cj , v _cj , and a _cj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the j-th dynamic obstacle around the vehicle collected by the binocular camera; x _dj , y _dj , v _dj , and a _dj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the j-th dynamic obstacle around the vehicle collected by mechanical lidar, respectively; x _wi , y _wi , v _wi , and a _wi are respectively are the longitudinal instantaneous position, lateral instantaneous position _, instantaneous speed _, and instantaneous acceleration of the _i - _th vehicle-by-wire chassis vehicle detected by the vehicle-to-vehicle communication system; Longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the vehicle by wire-controlled chassis; x _ni , y _ni , v _ni , and a _ni are the longitudinal and lateral instantaneous positions of the integrated non-wire-controlled chassis vehicle. Instantaneous speed, instantaneous acceleration, where n is the number of dynamic obstacles detected by mechanical lidar, j=1...n; k _w is the accuracy coefficient of interactive information; k _d is the accuracy coefficient of radar information; k _c is The camera information accuracy coefficient, k _w , k _d and k _c are all positive numbers less than 1; x _{d, ni} , y _{d, ni} , v _{d, ni} , a _{d, ni} are mechanical lidars, respectively The longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the ni-th dynamic obstacle around the vehicle collected; x _c,ni , y _c,ni , v _c,ni , a _c,ni are the binocular cameras, respectively The longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the ni-th dynamic obstacle around the vehicle are collected.

Correspondingly, a longitudinal active anti-collision control method, the chassis anti-collision control system includes an anti-collision mode with a communication function and an anti-collision mode without a communication function:

Anti-collision mode with communication function: According to the obstacle information data integrated by the environment and obstacle detection system, the vehicle-to-vehicle communication system and the cloud communication system, determine the collision risk of the own vehicle, and use the obstacle data and the corresponding control strategy to decide the out-of-line control The execution of the various systems of the chassis avoids collision with dynamic and static obstacles;

The anti-collision mode without communication function only judges the collision risk of the vehicle based on the dynamic and static obstacle information collected by the environment and obstacle detection system, and uses the obstacle data and the corresponding control strategy to decide the execution actions of each system of the drive-by-wire chassis. To avoid collision with dynamic and static obstacles, the specific algorithm is as follows:

A) Let the longitudinal distance d(t) between two adjacent cars at time t be:

d(t)= _xf (t)-x(t) or d(t)=x(t) _-xr (t)

In the formula, x _f (t) is the longitudinal position of the car in front of the chassis model by wire at time t, x(t) is the longitudinal position of the chassis model by wire at time t, and x _r (t) is the rear car of the chassis model by wire at time t The longitudinal position of , in meters;

B) The calculation formula of the longitudinal driving force or longitudinal braking force controlled by the chassis anti-collision control system at time t is:

为t时刻相邻辆车的纵向位置误差值的一阶导数；

为t时刻相邻辆车的纵向位置误差值的二阶导数；a_des(t)为t时刻滑模控制策略所得到的自车的期望加速度；v₁和v₂分别为相邻两车中前车的纵向车速和后车的纵向车速，单位为m/s；In the formula, F(t) is the longitudinal driving force or braking force of the vehicle at time t, the unit is N; m is the vehicle mass of the vehicle; q and k are the integral sliding mode coefficients; λ ₁ is the improved headway coefficient; F _a (t) and F _r (t) are the air resistance and rolling resistance at time t, respectively, and the unit is N;

is the first derivative of the longitudinal position error value of adjacent vehicles at time t;

is the second derivative of the longitudinal position error value of the adjacent vehicle at time t; a _des (t) is the expected acceleration of the vehicle obtained by the sliding mode control strategy at time t; v ₁ and v ₂ are the two adjacent vehicles, respectively The longitudinal speed of the preceding vehicle and the longitudinal speed of the rear vehicle, in m/s;

In the formula, λ is the integral sliding mode coefficient, dimensionless, e(t) is the longitudinal position error value of two adjacent vehicles at time t, the unit is m; s _i is the sliding mode surface, and G is a constant;

C) The front-end collision protection system judges the risk of collision between the front of the vehicle and the vehicle in front. When the difference between the longitudinal position of the vehicle with the closest distance in front of the vehicle and the longitudinal position of the vehicle is less than the desired distance, the front-end collision protection system is activated, in which the self-service front-end collision protection system is activated. The formula for calculating the expected longitudinal distance between the vehicle and the vehicle in front is:

In the formula, d _{x, des} is the expected distance between the ego vehicle and the preceding vehicle; v _x is the longitudinal speed of the ego vehicle; v _{x, f} is the longitudinal speed of the preceding vehicle; a _x is the longitudinal acceleration of the ego vehicle; a _{x, f} is the front Longitudinal acceleration of the vehicle; λ ₁ is the time distance coefficient of the improved vehicle head; λ ₂ is the speed proportional coefficient; λ ₃ is the acceleration difference coefficient; d is the minimum driving distance of the vehicle, the unit is m;

The front-end collision protection system is activated, and the braking force distribution formula is:

F _1,bra = 0.4F _bra

In the formula, F _1,bra , F _2,bra , F _3,bra are the braking forces distributed by the wheels of the first, second and third axles respectively; a _bra is the braking deceleration; F _bra is the braking force;

D) The rear-end collision protection system judges the risk of collision between the rear of the vehicle and the vehicle behind. When the longitudinal distance between the vehicle and the vehicle behind is less than the expected distance and there is no vehicle, obstacle or obstacle in front of the vehicle ahead, there is no threat. When the rear-end collision protection system is activated, the ego vehicle will be in an accelerating state. The formula for calculating the desired longitudinal distance between the ego car and the rear car is:

In the formula, d _{x, des'} is the desired distance between the ego vehicle and the preceding car; v _x is the longitudinal speed of the ego vehicle; v _{x, r} is the longitudinal speed of the rear car; a _x is the longitudinal acceleration of the ego vehicle; a _{x, r} is the longitudinal acceleration of the ego vehicle; The longitudinal acceleration of the rear vehicle; λ ₁ is the time distance coefficient of the improved headway, λ ₂ is the speed proportional coefficient, λ ₃ is the acceleration difference coefficient, d is the minimum driving distance of the vehicle, and the unit is m;

The rear-end collision protection system is activated, and the driving force distribution formula is:

F _acc,1 = 0.3F _acc

In the formula, F _acc,1 , F _acc,2 and F _acc,3 are the driving forces distributed by the wheels of the first, second and third axles respectively; a _acc is the acceleration; F _acc is the driving force;

E) When the two adjacent vehicles are both drive-by-wire chassis type vehicles, if the actual longitudinal distance between the two vehicles is less than the expected longitudinal distance between the two vehicles, the rear-end collision protection system of the front vehicle and the front-end protection of the rear vehicle The collision system works at the same time, the front car is in the acceleration state, the rear car is in the deceleration state, and the front and rear cars simultaneously activate the collision protection system.

The beneficial effects of the present invention are:

1. The six-wheel independent wire-controlled drive system and the six-wheel independent wire-controlled brake system in this system can make the wire-controlled chassis more refined and accurate to distribute the braking force and driving force of each wheel, so that the vehicle will adhere to the road surface. When the road conditions are different, the driving force and braking force of each wheel can be independently controlled, so that the drive-by-wire chassis vehicle can also achieve stable, safe and reliable driving on complex road surfaces.

2. The wire-controlled chassis anti-collision control system of this system is closely related to the information transmission of the intelligent surround view sensor system and communication system, and can accurately obtain the information of the external driving environment and surrounding obstacles, making the control operation of the wire-controlled chassis anti-collision control system fast and efficient. Timely and effective.

3. There are two types of active anti-collision control in this system, one is to protect the front-end collision, and the rear vehicle performs the braking operation to complete the active anti-collision; the other is to protect the rear-end collision, and the front vehicle accelerates to complete the active collision prevention Anti-collision. At the same time, when the front and rear cars are equipped with a wire-controlled chassis anti-collision control system, the front and rear cars can simultaneously activate the front-end collision protection and the rear-end collision protection, making the active anti-collision operation faster and realizing the collision avoidance operation in a shorter time.

4. The system compensates for the braking delay in the braking system, so that the braking delay phenomenon does not appear to the outside world, and the final braking effect is that there is no braking delay.

Description of drawings

1 is a schematic structural diagram of a longitudinal active anti-collision control system of the present invention;

FIG. 2 is a schematic flowchart of a longitudinal active collision avoidance control method according to the present invention.

Detailed ways

The technical solutions of the present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

As shown in Figure 1-2, a longitudinal active collision avoidance control system includes an environment and obstacle detection system. The environment and obstacle detection system is used to detect and collect environmental information and the position and relationship of obstacles on the front, rear, left, and right sides of the vehicle. Movement status information. The longitudinal active anti-collision control system further includes a chassis anti-collision control system, a wheel-independent drive-by-wire system, and a wheel-independent brake-by-wire system. The chassis anti-collision control system includes a front-end collision protection system and a rear-end collision protection system. The independent drive-by-wire system is used to apply an independent driving force to each wheel of the vehicle, and the wheel independent drive-by-wire system is used to apply an independent braking force to each wheel of the vehicle.

The chassis anti-collision control system is divided into a front-end collision protection system and a rear-end collision protection system. Through the joint action of the drive-by-wire, brake-by-wire, steering, and suspension, as well as the anti-collision control strategy, the longitudinal anti-collision of the chassis-by-wire vehicle is realized. Collision, for two-vehicle and multi-vehicle collision risk scenarios, its anti-collision system includes two types of anti-collision mode with communication function and ordinary anti-collision mode without communication function. In the case of a vehicle with a drive-by-wire chassis, the vehicle with a drive-by-wire chassis can activate the front-end collision protection system and the rear-end collision protection system at the same time.

The chassis anti-collision control system controls the braking force and driving force of each wheel according to the information collected by the environment and the obstacle detection system, so that the vehicle can achieve front-end collision protection and rear-end collision protection; the wheel independent brake-by-wire system includes a body stability module and a braking delay compensation module, the vehicle body stability module is used to ensure the stability of the vehicle, and the braking delay compensation module is used to compensate for the braking delay caused by the delay in the execution of the brake and the delay in the communication.

In order to improve the driving safety of the entire road and the reliability and intelligence of anti-collision, preferably, the longitudinal active anti-collision control system further includes a vehicle-to-vehicle communication system and a cloud communication system: the vehicle-to-vehicle communication system is used for a wire-controlled chassis model vehicle The information exchange between the vehicle and other types of vehicles; the cloud communication system is used to record the environment information data collected by the environment and obstacle detection system of the vehicle by wire, and transmit it. For the non-wire-controlled chassis model vehicles, the information records of the non-wire-controlled chassis type vehicles are fed back to the wire-controlled chassis type vehicles, so that all road vehicles participate in information exchange; the cloud communication system also includes an information integration unit A, the information The integration unit A integrates the information received by the cloud communication system, the obstacle information detected by the environment and the obstacle detection system, and the interactive information of the vehicle-to-vehicle communication system.

Generally, the environment and obstacle detection system includes an intelligent surround view sensor system, a wheel center relative height measuring instrument, an information integration unit B and a flatness information correction unit:

The intelligent surround-view sensor system includes a mechanical lidar on the top of the vehicle, a solid-state lidar at the lower part of the front of the vehicle, a binocular camera at the intersection of the top of the vehicle and the front, and a monocular camera at the rear of the vehicle.

The environment and obstacle detection system includes two different types of lidars, which are equipped with different types of radars in different positions of the vehicle. For example, a solid-state lidar can be installed above the front bumper of the vehicle, and the bottom surface of the solid-state lidar is far from the front bumper. The top of the bar is h _bum cm. The solid-state lidar is used to detect the position and shape information of ground bumps, depressions and low obstacles. It is assumed that the relative height of the i-th low obstacle on the uneven road around the vehicle collected by the solid-state lidar is h' _n,i , including the bumps. , depressions and low obstacles, h' _n,i can take positive and negative values, the unit is meters. When the height of the obstacle is lower than h _n0 cm, the solid-state lidar judges it as a low obstacle, and other height obstacles are obstacles that need to avoid collision and cannot be directly crossed.

A 32-line mechanical lidar can be installed above the front of the car at a distance of _{h rear} cm from the back of the car. The mechanical lidar is used to detect the position information of obstacles in front of and on the left and right sides of the vehicle. By receiving the position information of obstacles in real time, the internal computing unit of the vehicle calculates the position and motion state information of surrounding obstacles or other forms of vehicles. The information is the moving obstacle information and the stationary obstacle information, x _dj , y _dj , v _dj , and a _dj are the longitudinal and lateral instantaneous positions of the jth dynamic obstacle around the vehicle collected by the mechanical lidar respectively (unit: is m), instantaneous velocity (unit is m/s), instantaneous acceleration (m/s ² ), x _sk is the longitudinal position of the k-th static obstacle around the vehicle collected by the mechanical lidar, y _sk is the mechanical The lateral position unit of the kth static obstacle around the vehicle collected by the lidar is m.

The environment and obstacle detection system includes a binocular camera and a monocular camera. The binocular camera is installed in the middle of the front of the car at a vertical distance of h _top cm from the top of the car, and the monocular camera is installed in the middle of the rear of the vehicle chassis. Location. The binocular camera is used to detect the position information of obstacles in front of the vehicle and on the left and right sides. It is used to assist the mechanical lidar ranging in the daytime and when the outdoor light brightness meets the corresponding conditions, x _cj , y _cj , v _cj , a _cj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the jth dynamic obstacle around the vehicle collected by the binocular camera, respectively. The monocular camera is used to detect the position information of other vehicles behind the vehicle relative to the own vehicle. By receiving the obstacle position information in real time, the vehicle internal computing unit calculates the position and motion state information of the rear vehicle.

The above installation distances h _bum , h _rear , h _hig , and h _top are determined by the specific model and the size of the entire vehicle.

The information integration unit B integrates the information collected by the mechanical laser radar and the binocular camera with the vehicle interaction information collected by the vehicle-to-vehicle communication system and the cloud communication system to accurately determine the status of obstacles and surrounding vehicles. The information integration unit B compares, corrects, and fuses the computing unit inside the vehicle to obtain the final obstacle and other vehicle information. Preferably, the information integration unit B obtains the obstacle information after information integration as follows:

In the formula, x _cj , y _cj , v _cj , and a _cj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the j-th dynamic obstacle around the vehicle collected by the binocular camera; x _dj , y _dj , v _dj , and a _dj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the j-th dynamic obstacle around the vehicle collected by mechanical lidar, respectively; x _wi , y _wi , v _wi , and a _wi are respectively are the longitudinal instantaneous position, lateral instantaneous position _, instantaneous speed _, and instantaneous acceleration of the _i - _th vehicle-by-wire chassis vehicle detected by the vehicle-to-vehicle communication system; Longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the vehicle by wire-controlled chassis; x _ni , y _ni , v _ni , and a _ni are the longitudinal and lateral instantaneous positions of the integrated non-wire-controlled chassis vehicle. Instantaneous speed, instantaneous acceleration, where n is the number of dynamic obstacles detected by mechanical lidar, j=1...n; k _w is the accuracy coefficient of interactive information; k _d is the accuracy coefficient of radar information; k _c is The camera information accuracy coefficient, k _w , k _d and k _c are all positive numbers less than 1; x _{d, ni} , y _{d, ni} , v _{d, ni} , a _{d, ni} are mechanical lidars, respectively The longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the ni-th dynamic obstacle around the vehicle collected; x _c,ni , y _c,ni , v _c,ni , a _c,ni are the binocular cameras, respectively The longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the ni-th dynamic obstacle around the vehicle are collected.

k _w , k _d , and k _c are all non-negative numbers less than 1. The calculation method in the formula is proportional weight calculation. The accuracy coefficient of the camera information is affected by the intensity of natural light:

Eav＞30000lx,k _c =0.8

5000lx＜Eav≤30000lx,k _c =0.7

100lx＜Eav≤5000lx,k _c =0.5

Eav≤100lx,k _c =0

When the light intensity in the driving environment is greater than 30,000 lux, the value of k _c is 0.8; when the light intensity in the driving environment is greater than 5,000 lux and less than 30,000 lux, the value of k _c is 0.7; when the light intensity in the driving environment is greater than 100 lux and When the value of k c is less than 5000 lux, the value of k _c is 0.5; when the light intensity in the driving environment is less than 100 lux, the value of k _c is 0.

The flatness information correction unit corrects the flatness information of the surrounding road where the vehicle is traveling, which is collected by the solid-state lidar and the wheel center relative height measuring instrument. A flatness information correction unit, which compares and corrects the road surface flatness information measured by the wheel center relative height measuring instrument when the wheels of the first axle drive over the road surface and the information detected by the solid-state laser radar. Preferably, the flatness information correction unit The correction formula is:

In the formula, h _n,i is the relative height of the i-th uneven road low obstacle around the corrected vehicle, including bumps, depressions and low obstacles; h' _n,i and h'n _,i are solid-state lasers, respectively. The relative height of the ith uneven road low obstacle around the vehicle measured by radar detection and wheel center relative height measuring instrument, in meters; vx _is the longitudinal speed of the vehicle, in m/s; k _vx is the longitudinal speed influence factor, The unit is m/s.

Intelligent driving sensors such as in-vehicle lidar and cameras detect the external driving environment and information of obstacles around the vehicle, and deliver it to the wire-controlled chassis system through the in-vehicle network. The wire-controlled chassis system uses corresponding control strategies according to the external environment and obstacle information to complete the The independent braking and independent driving operation commands of the independent wheels, the drive-by-wire chassis control system and the intelligent sensor system are integrated to realize the stability and safety of the vehicle during driving.

The following takes a three-axle six-wheel vehicle as a specific example to describe in detail that the present invention collects the driving road environment and obstacle information through the information exchange between vehicles and the sensors mounted on the vehicle itself, so that the three-axle six-wheel vehicle can realize the front and rear of the vehicle when driving longitudinally. Active anti-collision at the place, complete the longitudinal control of the wire-controlled chassis through six-wheel independent driving and six-wheel independent braking, to ensure the safety and stability of the vehicle when driving longitudinally.

When the chassis anti-collision control system is used to control a three-axle six-wheel vehicle, the wheel-independent brake-by-wire system is a six-wheel independent-by-wire brake system; the wheel-independent drive-by-wire system is a six-wheel independent-by-wire drive system; All wheels are driving wheels, and each driving wheel includes three working modes: driving mode, follow-up mode and emptying mode: the driving mode means that the wheel is in contact with the ground, the suspension of the wheel is in a state of supporting the body, and its The drive motor works and is in a working state; the follow-up mode means that the wheels are in contact with the ground, the suspension of the wheels is in a state of supporting the body, but the drive motor does not work, and when other driving wheels drive the vehicle, the vehicle drives the follow-up The wheel rotates in the mode; the empty mode means that the wheel is not in contact with the ground, the suspension at the wheel controls the wheel to be in a raised state, the drive motor does not work, and the wheel does not rotate.

Preferably, the driving wheels of the first axle at the front end of the vehicle and the third axle at the rear end of the vehicle adopt the wheel-side drive mode, the driving wheel of the second axle in the middle of the vehicle adopts the in-wheel motor drive mode, and the wheel-side (motor) drive is driven by the use of a wheel mounted on the vehicle. The permanent magnet wheel side motors on both sides of the bridge are driven, which highly concentrates the motor, the reducer mechanism and the wheel hub into the wheel side motor drive axle, which is applied to the first and third axles of the on-line chassis model vehicle, while the wheel hub motor The drive adopts a high-speed inner rotor motor, which integrates the drive motor into the hub. According to the driving control parameters fed back by the chassis anti-collision control system, the six independent driving wheels are respectively assigned one of the driving mode, the follow-up mode and the emptying mode, so as to realize any combination of single-wheel to six-wheel drive of the whole vehicle.

The first axle at the front end of the vehicle and the third axle at the rear end of the vehicle adopt electro-hydraulic coupling brakes, and the second axle in the middle of the vehicle adopts electro-mechanical braking. The six-wheel independent brake-by-wire system includes two types of braking systems: electro-hydraulic coupling braking and electro-mechanical braking. Different braking systems are applied to the wheels of the three axles of the chassis-by-wire vehicle. The electro-hydraulic coupling braking system is applied to the first One-axle and three-axle wheels, the electro-mechanical braking system is applied to the wheels of the second axle.

Preferably, the six-wheel independent brake-by-wire system includes a body stability module and a braking delay compensation module, which are used to ensure vehicle stability and rapid braking. The body stability module can be composed of two parts, namely the body stability control system A composed of the first and third axes and the body stability control system B of the electronic mechanical braking system of the second axis. When the three axes of the vehicle are working normally and all the When the wheels are not in the empty mode, the body stability control system A and the body stability control system B work at the same time; when the second axle is in the empty mode, only the body stability control system A works normally. The wheel independent braking control status is:

In the formula, ΔM _Z is the expected yaw moment of the vehicle, the unit is Nm; F' _x2 is the longitudinal braking force of the right wheel of the first axis; ΔF _Y2 is the variation of the ground lateral force of the right wheel of the first axis; F' _x6 is the longitudinal braking force of the right wheel of the third axle; ΔF _Y6 is the change amount of the ground lateral force of the right wheel of the first axle, the unit is N; l ₁ is the horizontal longitudinal distance from the axis of the first axle of the vehicle to the center of mass ; l ₃ is the horizontal longitudinal distance from the center of the third axis of the vehicle to the center of mass, in meters; B ₁ is the distance from the center of the left and right wheels of the first axis to the center of the axis; B ₃ is the center of the left and right wheels of the third axis to the center of the axis distance, in meters; F' _X1 is the longitudinal braking force of the left wheel of the first axis; ΔF _Y1 is the change of the ground lateral force of the left wheel of the first axis; F' _X5 is the longitudinal direction of the left wheel of the third axis Braking force; ΔF _Y5 is the variation of the ground lateral force of the left wheel of the first axis; δ ₁ , δ ₂ , δ ₅ , δ ₆ are the rotation angles of the left and right wheels of the first axis and the left and right wheels of the third axis, unit is rad.

When the second axle is in the emptying mode, and only the first and third axle wheel brakes work, in order to maintain the stability of the vehicle body after simplification, the wheel cylinder pressure values of the four wheel brakes are:

In the formula, p ₁ , p ₂ , p ₅ , and p ₆ are the braking pressures of the left and right wheels of the first axis and the left and right wheels of the third axis, respectively, in MPa; F _Z1 , F _Z2 , F _Z5 , and F _Z6 respectively is the ground vertical force of the left and right wheels of the first axis and the left and right wheels of the third axis, in N; R _w1 and R _w3 are the radii of the wheels on the first and third axes, respectively, in meters; K _b is the braking pressure coefficient, which is the ratio of the wheel braking torque to the wheel cylinder pressure; ΔM _Z is the expected yaw moment of the vehicle, in Nm; B ₁ is the distance from the center of the left and right wheels of the first axis to the axle center, B ₃ is the distance from the center of the left and right wheels of the third axis to the axle center, the unit is meters; δ ₁ , δ ₂ , δ ₅ , δ ₆ are the rotation angles of the left and right wheels of the first axis and the left and right wheels of the third axis, the unit is rad .

The braking delay compensation module is used for compensating the braking delay caused by the delay of the brake execution and the delay of communication. Preferably, the calculation formula of the compensation wheel cylinder pressure value is:

In the formula, p _com is the compensation wheel cylinder pressure value, t ₁ is the communication delay time, t ₂ ' is the time taken for the brake clearance to decrease, t ₂ " is the time taken for the brake to be gradually pressed to a stable state, and p(t) is the time t. Brake wheel cylinder pressure value, the unit is MPa; within the time period of t ₁ +t ₂ '+t ₂ ”/2 after the brake takes effect, the value of p _pro is 30%-80% of the maximum wheel cylinder pressure value , the unit is MPa, the value of p _pro depends on the braking deceleration value in the chassis anti-collision control system:

pro=30 a<2.5m/s ²

pro＝30+k _bra (a _bra -2.5) 2.5m/s ² ≤a≤7.5m/s ²

pro=80 a＞7.5m/s ²

In the ^formula , _{k bra} is the proportional factor of braking deceleration, a _bra is the braking deceleration feedback feedback in the chassis anti-collision control system, when the braking deceleration is less than 2.5m/s When the dynamic deceleration is greater than 7.5m/s ² , the value of p _pro is 80.

The vehicle-to-vehicle communication system is used for the information interaction between the vehicle-by-wire chassis vehicle and the information interaction between the vehicle-by-wire vehicle and other vehicles. The longitudinal position x _wi ; the lateral position y _wi of the wire-controlled chassis model vehicle, the unit is m; the speed v _wi of the wire-controlled chassis model vehicle, the unit is m/s; the acceleration of the wire-controlled chassis model vehicle a _wi , the unit is m /s ² ), and the expected behavior of the chassis system of the drive-by-wire chassis model vehicle (comprising six wheel drive torques T _di , six wheel brake wheel cylinder pressures pi , where _i =1...6).

The vehicle-to-vehicle communication system adopts a multi-member hierarchical intercommunication communication method. The vehicles involved in the communication include vehicles with wire-controlled chassis models, non-wire-controlled chassis vehicles equipped with lidar and cameras, and non-wire-controlled chassis vehicles without radar cameras. The communication is divided into three types. Interoperability communication method:

The first-level communication is to interact with the vehicle information of the wire-controlled chassis models. When the first-level communication interaction is successfully connected, the second-level communication is activated. The information interaction level of vehicles that have not completed the information interaction within the set interaction time is reduced to the third-level communication. The third-level communication is the information exchange with non-wire-controlled chassis vehicles without radar cameras and vehicles that have not successfully interacted with the second-level communication. The intercommunication communication mode adopts a multi-vehicle full-duplex multi-channel mode, which ensures that a plurality of wire-controlled chassis model vehicles send and receive communication information at the same time.

The cloud communication system can store and record the driving environment information data transmitted by the environment and obstacle detection system of the chassis-by-wire vehicle, send it to other vehicles, and at the same time receive the status information of other vehicles and send it to the chassis-by-wire vehicle, cloud The communication system performs information fusion with the obstacle information detected by the environment and obstacle detection system and the interaction information of the vehicle-to-vehicle communication system. The information sending and receiving function of the cloud communication system can assist in the vehicle-to-vehicle communication of the wire-controlled chassis models. For other vehicles that cannot conduct real-time information exchange with the wire-controlled chassis models, the cloud can be used to receive other vehicle information and broadcast it to realize the interconnection of all vehicles. At the same time, vehicles without lidar and cameras can receive the driving road environment information stored in the cloud.

Correspondingly, a longitudinal active anti-collision control method, the chassis anti-collision control system includes an anti-collision mode with a communication function and an anti-collision mode without a communication function:

Anti-collision mode with communication function: According to the obstacle information data integrated by the environment and obstacle detection system, the vehicle-to-vehicle communication system and the cloud communication system, determine the collision risk of the own vehicle, and use the obstacle data and the corresponding control strategy to decide the out-of-line control The execution of the various systems of the chassis avoids collision with dynamic and static obstacles;

The anti-collision mode without communication function only judges the collision risk of the own vehicle according to the dynamic and static obstacle information collected by the environment and obstacle detection system, and uses the obstacle data and the corresponding control strategy (sliding mode control strategy can be selected) to decide the line. Control the execution of the various systems of the chassis to avoid collision with dynamic and static obstacles. The specific algorithm is as follows:

A) Let the longitudinal distance d(t) between two adjacent cars at time t be:

d(t)= _xf (t)-x(t) or d(t)=x(t) _-xr (t)

In the formula, x _f (t) is the longitudinal position of the vehicle in front of the chassis-by-wire model at time t (that is, the time-varying function of the longitudinal position of the vehicle in front of the chassis-by-wire model, the following definitions are similar and will not be repeated), x(t ) is the longitudinal position of the wire-controlled chassis model at time t, and x _r (t) is the longitudinal position of the vehicle behind the wire-controlled chassis model at time t, in meters;

B) The calculation formula of the longitudinal driving force or longitudinal braking force controlled by the chassis anti-collision control system at time t is:

为t时刻相邻辆车的纵向位置误差值的一阶导数；

为t时刻相邻辆车的纵向位置误差值的二阶导数；a_des(t)为t时刻滑模控制策略所得到的自车的期望加速度；v₁和v₂分别为相邻两车中前车的纵向车速和后车的纵向车速，单位为m/s；相应控制策略为滑模控制策略，其适用于自车仅在防护前端碰撞与防护后端碰撞系统，选用包含积分项的滑模面与趋近律分别为：In the formula, F(t) is the longitudinal driving force or braking force of the vehicle at time t, the unit is N; m is the vehicle mass of the vehicle; q and k are the integral sliding mode coefficients; λ ₁ is the improved headway coefficient; F _a (t) and F _r (t) are the air resistance and rolling resistance at time t, respectively, and the unit is N;

is the first derivative of the longitudinal position error value of adjacent vehicles at time t;

is the second derivative of the longitudinal position error value of the adjacent vehicle at time t; a _des (t) is the expected acceleration of the vehicle obtained by the sliding mode control strategy at time t; v ₁ and v ₂ are the two adjacent vehicles, respectively The longitudinal speed of the front car and the longitudinal speed of the rear car, in m/s; the corresponding control strategy is the sliding mode control strategy, which is suitable for the self-vehicle only in the front-end collision protection and rear-end collision protection systems. The die surface and the reaching law are:

In the formula, λ is the integral sliding mode coefficient, dimensionless, e(t) is the longitudinal position error value of two adjacent vehicles at time t, the unit is m; s _i is the sliding mode surface, G is a constant, where e( t) It can be calculated according to the actual distance between the wire-controlled chassis vehicle and the front and rear vehicles and the longitudinal expected distance between the own vehicle and the preceding vehicle at time t:

e(t)=d(t)-d _x,des (t)

where d _{x, des} (t) is the expected longitudinal distance between the ego vehicle and the preceding vehicle at time t, in meters;

C) The front-end collision protection system judges the risk of collision between the front of the vehicle and the vehicle in front. When the difference between the longitudinal position of the vehicle with the closest distance in front of the vehicle and the longitudinal position of the vehicle is less than the desired distance, the front-end collision protection system is activated, in which the self-service front-end collision protection system is activated. The formula for calculating the expected longitudinal distance between the vehicle and the vehicle in front is:

In the formula, d _{x, des} is the expected distance between the ego vehicle and the preceding vehicle; v _x is the longitudinal speed of the ego vehicle; v _{x, f} is the longitudinal speed of the preceding vehicle; a _x is the longitudinal acceleration of the ego vehicle; a _{x, f} is the front Longitudinal acceleration of the vehicle; λ ₁ is the time distance coefficient of the improved vehicle head; λ ₂ is the speed proportional coefficient; λ ₃ is the acceleration difference coefficient; d is the minimum driving distance of the vehicle, the unit is m;

In the front-end collision protection system, when the road surface adhesion coefficient is the same, the left and right braking force distribution of each axle is the same, the braking force distribution ratio of the wheels of the first axle is fixed, and the braking force distribution of the second axle and the third axle is determined by The braking acceleration is determined, and the braking force distribution formula is:

F _1,bra = 0.4F _bra

In the formula, F _1,bra , F _2,bra , F _3,bra are the braking forces distributed by the wheels of the first, second and third axles respectively; a _bra is the braking deceleration; F _bra is the braking force;

D) The rear-end collision protection system judges the risk of collision between the rear of the vehicle and the vehicle behind. When the longitudinal distance between the vehicle and the vehicle behind is less than the expected distance and there is no vehicle, obstacle or obstacle in front of the vehicle ahead, there is no threat. When the rear-end collision protection system is activated, the ego vehicle will be in an accelerating state. The formula for calculating the desired longitudinal distance between the ego car and the rear car is:

In the formula, d _{x, des'} is the desired distance between the ego vehicle and the preceding car; v _x is the longitudinal speed of the ego vehicle; v _{x, r} is the longitudinal speed of the rear car; a _x is the longitudinal acceleration of the ego vehicle; a _{x, r} is the longitudinal acceleration of the ego vehicle; The longitudinal acceleration of the rear vehicle; λ ₁ is the time distance coefficient of the improved headway, λ ₂ is the speed proportional coefficient, λ ₃ is the acceleration difference coefficient, d is the minimum driving distance of the vehicle, and the unit is m;

In the rear-end collision protection system, when the road surface adhesion coefficient is the same, the left and right driving force distribution of each axle is the same, the driving force distribution ratio of the wheels of the first axle is fixed, and the driving force distribution of the second axle and the third axle Determined by the magnitude of the acceleration, the driving force distribution formula is:

F _acc,1 = 0.3F _acc

In the formula, F _acc,1 , F _acc,2 and F _acc,3 are the driving forces distributed by the wheels of the first, second and third axles respectively; a _acc is the acceleration; F _acc is the driving force;

E) When the two adjacent vehicles are both drive-by-wire chassis type vehicles, if the actual longitudinal distance between the two vehicles is less than the expected longitudinal distance between the two vehicles, the rear-end collision protection system of the front vehicle and the front-end protection of the rear vehicle The collision system works at the same time, the front car is in the acceleration state, the rear car is in the deceleration state, and the front and rear cars simultaneously start the collision protection system, which will shorten the time of the vehicle shifting movement.

The invention discloses a longitudinal active anti-collision control system and method, aiming at solving the safety problem when the vehicle is running at high speed in the longitudinal direction. The vehicle's own sensors collect data and use the inter-vehicle communication system to collect obstacle information, determine whether the vehicle is in a safe state at the current moment, and control the start of the anti-collision control in the chassis anti-collision control system. There are two types of end anti-collision. The current and rear vehicles are equipped with wire-controlled chassis, and the front and rear vehicles both start the chassis anti-collision control to ensure the safety and stability of the vehicle during longitudinal driving.

The above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied in other related technical fields , are similarly included in the scope of patent protection of the present invention.

Claims (7)

1. A longitudinal active anti-collision control system, including an environment and obstacle detection system, the environment and obstacle detection system is used to detect and collect environmental information and the position and motion state information of obstacles on the left and right sides of the vehicle. It also includes a chassis anti-collision control system, a wheel independent wire-controlled drive system and a wheel independent wire-controlled brake system, the chassis anti-collision control system includes a front-end collision protection system and a rear-end collision protection system, and the wheel independent wire-controlled drive system The system is used to apply an independent driving force to each wheel of the vehicle, the wheel independent brake-by-wire system is used to apply an independent braking force to each wheel of the vehicle, and the chassis anti-collision control system is collected according to the environment and the obstacle detection system The information controls the braking force and driving force of each wheel so that the vehicle can achieve front-end collision protection and rear-end collision protection; the wheel independent brake-by-wire system includes a body stability module and a braking delay compensation module, and the body stability module is used to ensure The vehicle is stable, and the braking delay compensation module is used to compensate the braking delay caused by the delay in the execution of the brake and the delay in the communication; The chassis anti-collision control system is used to control a three-axle six-wheel vehicle, the wheel independent wire-controlled drive system is a six-wheel independent wire-controlled drive system, the six wheels are all driving wheels, and each driving wheel includes a driving mode, a follow-up mode Three working modes with venting mode; The wheel independent brake-by-wire system is a six-wheel independent brake-by-wire system, and the vehicle body stability module and the brake delay compensation module are used to ensure the vehicle's own stability and non-delay braking during braking; The driving wheel of the first axle at the front end of the vehicle and the third axle at the rear end of the vehicle adopts the wheel-side drive mode, the driving wheel of the second axle in the middle of the vehicle adopts the in-wheel motor drive mode, and the first axle at the front end of the vehicle and the third axle at the rear end of the vehicle adopt the in-wheel motor drive mode. The electro-hydraulic coupling brake is adopted, and the second axle in the middle of the vehicle adopts the electro-mechanical brake; When the second axle is in the emptying mode and only the wheel brakes of the first and third axles are working, the wheel cylinder pressure values of the four wheel brakes of the first and third axles are:

In the formula, p ₁ , p ₂ , p ₅ , and p ₆ are the braking pressures of the left and right wheels of the first axis and the left and right wheels of the third axis, respectively, in MPa; F _Z1 , F _Z2 , F _Z5 , and F _Z6 respectively is the ground vertical force of the left and right wheels of the first axis and the left and right wheels of the third axis, in N; R _w1 and R _w3 are the radii of the wheels on the first and third axes, respectively, in meters; K _b is the braking pressure coefficient, which is the ratio of the wheel braking torque to the wheel cylinder pressure; ΔM _Z is the expected yaw moment of the vehicle, in Nm; B ₁ is the distance from the center of the left and right wheels of the first axis to the axle center, B ₃ is the distance from the center of the left and right wheels of the third axis to the axle center, the unit is meters; δ ₁ , δ ₂ , δ ₅ , δ ₆ are the rotation angles of the left and right wheels of the first axis and the left and right wheels of the third axis, the unit is rad . 2. A longitudinal active anti-collision control system according to claim 1, further comprising a vehicle-to-vehicle communication system and a cloud communication system: the vehicle-to-vehicle communication system is used to control information between vehicles of chassis models by wire Interaction, and the information interaction between the wire-controlled chassis model vehicle and other types of vehicles; the cloud communication system is used to record the environment of the wire-controlled chassis model vehicle and the environmental information data collected by the obstacle detection system, and transmit it to the non-wire-controlled vehicle. At the same time, the information records of the non-wire-controlled chassis type vehicles are fed back to the wire-controlled chassis type vehicles, so that all road vehicles participate in the information exchange; the cloud communication system also includes an information integration unit A, and the information integration unit A will The information received by the cloud communication system, the obstacle information detected by the environment and obstacle detection system, and the interactive information of the vehicle-to-vehicle communication system are integrated. 3. A longitudinal active anti-collision control system according to claim 2, wherein the environment and obstacle detection system comprises an intelligent surround view sensor system, a wheel center relative height measuring instrument, an information integration unit B and a flatness Information correction unit: The intelligent surround view sensor system includes a mechanical lidar on the top of the vehicle, a solid-state lidar on the front of the vehicle, a binocular camera at the intersection of the top of the vehicle and the front, and a monocular camera at the rear of the vehicle; The information integration unit B integrates the information collected by the mechanical laser radar and the binocular camera with the vehicle interaction information collected by the vehicle-to-vehicle communication system and the cloud communication system to accurately determine the status of obstacles and surrounding vehicles; The flatness information correction unit corrects the flatness information of the surrounding road where the vehicle is traveling, which is collected by the solid-state lidar and the wheel center relative height measuring instrument. 4. A kind of longitudinal active anti-collision control system according to claim 1, is characterized in that, the compensation wheel cylinder pressure value of brake delay compensation module is:

In the formula, p _com is the compensation wheel cylinder pressure value, t ₁ is the communication delay time, t ₂ ' is the time taken for the brake clearance to decrease, t ₂ '' is the time taken for the brake to be gradually pressed to a stable state, and the time after the brake starts to work. During the time period of t ₁ +t ₂ '+t ₂ ”/2, the value of p _pro is 30%-80% of the maximum wheel cylinder pressure value, the unit is MPa, and the value of p _pro depends on the chassis collision avoidance control system. Brake deceleration value, p(t) is the pressure value of the brake wheel cylinder at time t, the unit is MPa. 5. A longitudinal active anti-collision control system according to claim 3, wherein the correction formula of the flatness information correction unit is:

In the formula, h _n,i is the corrected relative height of the i-th low obstacle on the uneven road around the vehicle; h' _n,i and h'n _,i are measured by solid-state lidar detection and wheel center relative height measuring instrument, respectively. The relative height of the low obstacle on the ith uneven road around the vehicle, in meters; vx _is the longitudinal speed of the vehicle, in m/s; k _vx is the longitudinal speed influence factor, in m/s. 6. A kind of longitudinal active anti-collision control system according to claim 3, is characterized in that, the obstacle information after the information integration of described information integration unit B is:

In the formula, x _cj , y _cj , v _cj , and a _cj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the j-th dynamic obstacle around the vehicle collected by the binocular camera; x _dj , y _dj , v _dj , and a _dj are the longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the j-th dynamic obstacle around the vehicle collected by mechanical lidar, respectively; x _wi , y _wi , v _wi , and a _wi are respectively are the longitudinal instantaneous position, lateral instantaneous position _, instantaneous speed _, and instantaneous acceleration of the _i - _th vehicle-by-wire chassis vehicle detected by the vehicle-to-vehicle communication system; Longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the vehicle by wire-controlled chassis; x _ni , y _ni , v _ni , and a _ni are the longitudinal and lateral instantaneous positions of the integrated non-wire-controlled chassis vehicle. Instantaneous speed, instantaneous acceleration, where n is the number of dynamic obstacles detected by mechanical lidar, j=1...n; k _w is the accuracy coefficient of interactive information; k _d is the accuracy coefficient of radar information; k _c is The camera information accuracy coefficient, k _w , k _d and k _c are all positive numbers less than 1; x _{d, ni} , y _{d, ni} , v _{d, ni} , a _{d, ni} are mechanical lidars, respectively The longitudinal instantaneous position, lateral instantaneous position, instantaneous velocity, and instantaneous acceleration of the ni-th dynamic obstacle around the vehicle collected; x _c,ni , y _c,ni , v _c,ni , a _c,ni are the binocular cameras, respectively The longitudinal instantaneous position, lateral instantaneous position, instantaneous speed, and instantaneous acceleration of the ni-th dynamic obstacle around the vehicle are collected. 7. A longitudinal active anti-collision control method, wherein the chassis anti-collision control system comprises an anti-collision mode with a communication function and an anti-collision mode without a communication function: Anti-collision mode with communication function: According to the obstacle information data integrated by the environment and obstacle detection system, the vehicle-to-vehicle communication system and the cloud communication system, determine the collision risk of the own vehicle, and use the obstacle data and the corresponding control strategy to decide the out-of-line control The execution of the various systems of the chassis avoids collision with dynamic and static obstacles; The anti-collision mode without communication function only judges the collision risk of the vehicle based on the dynamic and static obstacle information collected by the environment and obstacle detection system, and uses the obstacle data and the corresponding control strategy to decide the execution actions of each system of the drive-by-wire chassis. To avoid collision with dynamic and static obstacles, the specific algorithm is as follows: A) Let the longitudinal distance d(t) between two adjacent cars at time t be: d(t)= _xf (t)-x(t) or d(t)=x(t) _-xr (t) In the formula, x _f (t) is the longitudinal position of the car in front of the chassis model by wire at time t, x(t) is the longitudinal position of the chassis model by wire at time t, and x _r (t) is the rear car of the chassis model by wire at time t The longitudinal position of , in meters; B) The calculation formula of the longitudinal driving force or longitudinal braking force controlled by the chassis anti-collision control system at time t is:

In the formula, F(t) is the longitudinal driving force or braking force of the vehicle at time t, the unit is N; m is the vehicle mass of the own vehicle; q and k are the integral sliding mode coefficients; λ ₁ is the improved headway coefficient; F _a (t) and F _r (t) are the air resistance and rolling resistance at time t, respectively, and the unit is N;

is the first derivative of the longitudinal position error value of two adjacent vehicles at time t;

is the second derivative of the longitudinal position error value of the two adjacent vehicles at time t; a _des (t) is the expected acceleration of the vehicle obtained by the sliding mode control strategy at time t; v ₁ and v ₂ are the two adjacent vehicles, respectively The longitudinal speed of the preceding vehicle and the longitudinal speed of the rear vehicle, in m/s;

In the formula, e(t) is the longitudinal position error value of two adjacent vehicles at time t, the unit is m; s _i is the sliding surface, and G is a positive number; C) The front-end collision protection system judges the risk of collision between the front of the vehicle and the vehicle in front. When the difference between the longitudinal position of the vehicle with the closest distance in front of the vehicle and the longitudinal position of the vehicle is less than the desired distance, the front-end collision protection system is activated, in which the self-service front-end collision protection system is activated. The formula for calculating the expected longitudinal distance between the vehicle and the vehicle in front is:

In the formula, d _{x, des} is the expected distance between the ego vehicle and the preceding vehicle; v _x is the longitudinal speed of the ego vehicle; v _{x, f} is the longitudinal speed of the preceding vehicle; a _x is the longitudinal acceleration of the ego vehicle; a _{x, f} is the front Longitudinal acceleration of the vehicle; λ ₁ is the time distance coefficient of the improved vehicle head; λ ₂ is the speed proportional coefficient; λ ₃ is the acceleration difference coefficient; d is the minimum driving distance of the vehicle, the unit is m; The front-end collision protection system is activated, and the braking force distribution formula is: F _1,bra = 0.4F _bra

In the formula, F _1,bra , F _2,bra , F _3,bra are the braking forces distributed by the wheels of the first, second and third axles respectively; a _bra is the braking deceleration; F _bra is the braking force; D) The rear-end collision protection system judges the risk of collision between the rear of the vehicle and the vehicle behind. When the longitudinal distance between the vehicle and the vehicle behind is less than the expected distance and there is no vehicle, obstacle or obstacle in front of the vehicle ahead, there is no threat. When the rear-end collision protection system is activated, the ego vehicle will be in an accelerating state. The formula for calculating the desired longitudinal distance between the ego car and the rear car is:

In the formula, d _{x, des'} is the desired distance between the ego vehicle and the preceding car; v _x is the longitudinal speed of the ego vehicle; v _{x, r} is the longitudinal speed of the rear car; a _x is the longitudinal acceleration of the ego vehicle; a _{x, r} is the longitudinal acceleration of the ego vehicle; The longitudinal acceleration of the rear vehicle; λ ₁ is the time distance coefficient of the improved headway, λ ₂ is the speed proportional coefficient, λ ₃ is the acceleration difference coefficient, d is the minimum driving distance of the vehicle, and the unit is m; The rear-end collision protection system is activated, and the driving force distribution formula is: F _acc,1 = 0.3F _acc

In the formula, F _acc,1 , F _acc,2 and F _acc,3 are the driving forces distributed by the wheels of the first, second and third axles respectively; a _acc is the acceleration; F _acc is the driving force; E) When the two adjacent vehicles are both drive-by-wire chassis type vehicles, if the actual longitudinal distance between the two vehicles is less than the expected longitudinal distance between the two vehicles, the rear-end collision protection system of the front vehicle and the front-end protection of the rear vehicle The collision system works at the same time, the front car is in the acceleration state, the rear car is in the deceleration state, and the front and rear cars simultaneously activate the collision protection system.

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