Anti-rear-end collision system based on millimeter-wave radar

Abstract

The present invention discloses an anti-rear-end collision system based on millimeter-wave radar. The millimeter-wave radar is arranged around the vehicle body to detect and obtain vehicle condition information around the vehicle body; the vehicle body CAN network receives the vehicle condition information around the vehicle body and sends it to the vehicle system main control; the vehicle system main control determines whether safe emergency steering can be performed based on the vehicle condition information around the vehicle body and the vehicle information itself: if safe emergency steering can be performed, a steering control signal is generated and sent to the steering control module; the steering control module controls the steering wheel of the vehicle to perform emergency steering according to the steering control signal sent by the vehicle system main control to prevent rear-end collision. The present invention aims at the accident in which the small car in the middle position is crushed due to the current intelligent driving safety system ignoring the rear-end collision of the rear vehicle, and adopts the measures of alarm and emergency steering to reduce or avoid such risks.

Description

Technical Field

[0001] The invention relates to an automobile auxiliary control system, and in particular to an anti-rear-end collision system and a control method based on millimeter-wave radar. Background Art

[0002] By analyzing the data of road traffic accidents, the following tragic accidents often occur: a cement mixer truck is in front, a heavy dump truck is behind, and a small car is sandwiched in the middle. The heavy dump truck behind loses control and accelerates due to driver misoperation or fatigue driving, causing the small car sandwiched in front and back to be squeezed and deformed, and the passengers in the car are crushed, causing heavy casualties. At present, the installation rate of emergency braking system AEB is gradually increasing, which has played a good control role in preventing the front vehicle collision accident rate, but it is a blank area for preventing active collisions from rear vehicles. Because most drivers focus on the road ahead and often ignore sudden collisions from rear vehicles, once they encounter a collision with a high-speed vehicle behind them, or a collision with a heavy engineering vehicle behind them, they will be at a loss, which can easily lead to a tragedy of car destruction and death. Summary of the invention

[0003] In order to solve the problems existing in the background technology, the present invention provides an anti-rear-end collision system and control method based on millimeter-wave radar, which effectively reduces the occurrence of collision accidents and protects the safety of people and property.

[0004] The technical solution adopted by the present invention is:

[0005] 1. A rear-end collision prevention system based on millimeter-wave radar:

[0006] It includes millimeter wave radar, which is arranged around the vehicle body to detect and obtain vehicle condition information around the vehicle body and send it to the vehicle body CAN network;

[0007] Including the vehicle body CAN network, which receives vehicle condition information around the vehicle body from the millimeter wave radar and sends it to the vehicle system master control;

[0008] It includes the vehicle system main control, which receives the vehicle condition information around the vehicle body from the millimeter-wave radar through the CAN network, collects the vehicle information itself, and determines whether a safe emergency turn can be made by combining the vehicle condition information around the vehicle body and the vehicle information itself: if a safe emergency turn can be made, a safe steering obstacle avoidance path is generated, and a steering control signal is generated according to the steering obstacle avoidance path conversion and sent to the steering control module;

[0009] It includes a steering control module, which controls the vehicle's steering wheel for emergency steering according to the steering control signal sent by the vehicle system main control to prevent rear-end collision.

[0010] The millimeter-wave radar at the rear of the vehicle faces backward to detect the longitudinal distance between the vehicle and the following vehicle.

[0011] There is a millimeter-wave radar installed around the vehicle body.

[0012] The vehicle system master generates a prompt alarm message while generating a steering control signal and displays it on the main console to remind the driver.

[0013] 2. A rear-end collision warning method applied to a rear-end collision prevention system:

[0014] In the vehicle system master control, the distance D and relative speed between the current vehicle and the following vehicle are obtained in real time through the millimeter wave radar, and the collision risk is identified in the following manner to determine whether there is a risk of rear-end collision:

[0015]

[0016] Where D is the longitudinal distance between the vehicle and the following vehicle detected by the millimeter wave radar, V1, V rel are the speed and relative speed of the rear vehicle respectively; a1 and a2 are the preset maximum braking decelerations of the rear vehicle and the vehicle respectively; t1 and t2 are the preset system delay time and driver reaction time in the rear-end collision system respectively; d0 is the safe vehicle distance to be maintained;

[0017] If the above formula is satisfied, it is determined that a rear-end collision will not occur;

[0018] When the above formula is not satisfied, it is determined that a rear-end collision will occur and the anti-rear-end collision system will be controlled.

[0019] In the vehicle system master control, if it is determined that there is a risk of rear-end collision, a safe emergency turn is performed in the following manner:

[0020] If the millimeter-wave radar detects that there is no vehicle within the preset distance d in front of the current vehicle, the vehicle speed will be accelerated to the speed V1 equal to the speed of the vehicle behind, and the longitudinal acceleration a x Satisfies the following formula:

[0021]

[0022] If the millimeter-wave radar detects a vehicle within a preset distance d in front of the current vehicle, the current vehicle will perform lane change control:

[0023] When the millimeter-wave radar detects that there is a vehicle within a preset distance d in front of the current vehicle, the B-spline curve is used to simulate the path planning of lane change control. The B-spline curve consists of n+1 control points P i Composition, i = 0, 1, ..., n, the B-spline curve parameterization of the steering obstacle avoidance path is:

[0024]

[0025] Where k is the degree of the B-spline curve, N i,k () is the k-order B-spline curve basis function; i represents the ordinal number of the control point, P i represents the coordinates of the i-th control point; C(u) represents the coordinates of the steering obstacle avoidance path;

[0026] The quintic B-spline curve is selected to plan the steering obstacle avoidance path with the quintic B-spline curve, where the coordinates of each control point P i That is:

[0027]

[0028] Wherein, L is the lane width, θ represents the turning curvature of the turning obstacle avoidance path, d1, d2, d3, and d4 represent the spacing between the first pair of adjacent control points along the vehicle driving direction, the spacing between the second pair of adjacent control points along the vehicle driving direction, the spacing between the third pair of adjacent control points along the vehicle driving direction, and the spacing between the fourth pair of adjacent control points along the vehicle driving direction, respectively;

[0029] At the same time, when the vehicle is driving along the steering obstacle avoidance path, the curvature ρ is calculated in real time according to the following formula:

[0030]

[0031] in, and are the first-order derivatives of the coordinates C(u) of the steering obstacle avoidance path about the x-axis and y-axis, respectively. and is the second-order derivative of the coordinate C(u) of the steering obstacle avoidance path about the x-axis and y-axis;

[0032] Then, the lateral acceleration a of the car when changing lanes is obtained according to the curvature ρ obtained in real time. y And send it to the vehicle system master for acceleration control:

[0033]

[0034] Among them, V2 represents the current speed of the vehicle.

[0035] The present invention is mainly aimed at avoiding the difficulty of the driver not noticing the collision risk from the rear, or realizing the collision risk from the rear through the rearview mirror but not reacting in time in such an emergency situation where a collision accident is about to occur. The anti-rear-end collision system can firstly give a timely alarm for such rear-end collision risk, and secondly, for the vehicle conditions where there are large vehicles in front and behind the vehicle and there is a tendency to squeeze, it can change lanes in time to avoid the accident of being squeezed. The present invention is mainly combined with such situations, and 4 millimeter-wave radars are installed around the vehicle to sense the surrounding vehicle conditions. When a collision accident is about to occur, the system can determine whether it can effectively avoid collision and calculate a safe and stable steering path based on the vehicle condition information obtained by the millimeter-wave radar, if the space on both sides of the vehicle meets the emergency steering requirements, and the system will monitor whether the driver has the intention to turn. If such an intention is found, the control command is sent to the steering control module through the CAN network to control the steering wheel to perform effective collision avoidance actions. Through effective collision avoidance behavior, the system can significantly avoid such traffic accidents and reduce casualties and property losses.

[0036] This system mainly relies on the millimeter-wave radar installed around the vehicle body to sense and monitor the surrounding road conditions. When the millimeter-wave radar recognizes the presence of a vehicle behind and transmits the vehicle information to the system master through the CAN network, and the system master determines that the rear vehicle is about to collide with the vehicle based on the information of its own vehicle and the rear vehicle, the system calculates a safe and stable lane change trajectory based on the current surrounding vehicle conditions and determines that it is safe to turn and change lanes, and then sends a control command to the steering control module and sends a prompt alarm message to remind the driver to pay attention to steering safety. The steering control module controls the steering wheel along the previously calculated trajectory, and can safely turn before the original collision point to prevent collision and protect the safety of the passengers in the car. If there is no avoidable space on both sides, an alarm prompt will be issued for the driver to decide on the avoidance measures.

[0037] The beneficial effects of the present invention are:

[0038] The present invention is an effective supplement to active collision avoidance technology. The system mainly solves the problem that the current ADAS system focuses more on the risk of forward collision avoidance and ignores the risk of rear-end collision avoidance from the rear. Especially in the case where there is a large vehicle in front of the rear-end vehicle and a large vehicle behind it for forward collision, if there is space on the side, the vicious traffic accident of being crushed by the rear-end collision can be avoided.

[0039] The present invention effectively improves the safety of the vehicle when a collision accident is about to occur, and further protects the safety of the passengers in the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A top view of the system block diagram of an emergency steering system based on millimeter-wave radar;

[0041] In the figure: 1-4, millimeter wave radar, 5, system main control, 6, steering control module, 7, CAN network.

[0042] Figure 2 A schematic diagram of a rear-end collision when there is no vehicle in front of the rear-end vehicle;

[0043] In the figure: D is the distance between the current vehicle and the vehicle behind obtained by the millimeter wave radar in real time. V1 is the speed of the vehicle behind, V2 is the current speed of the vehicle, and a1 is the acceleration automatically controlled by the system.

[0044] Figure 3 A schematic diagram of a rear-end collision when there is a vehicle in front of the rear-end vehicle;

[0045] In the figure: D is the distance between the vehicle and the vehicle behind obtained by the millimeter wave radar in real time, d is the safe distance for the vehicle to determine whether to change lanes. V1 is the speed of the vehicle behind, V2 is the current speed of the vehicle, and V3 is the speed of the vehicle in front.

[0046] Figure 4 Schematic diagram of steering obstacle avoidance path planning using quintic B-spline curve. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] like Figure 1 As shown, the system includes:

[0049] It includes millimeter wave radars 1-4, which are arranged around the vehicle body, detect and obtain vehicle condition information around the vehicle body, and send it to the vehicle body CAN network 7;

[0050] It includes a vehicle body CAN network 7, which receives vehicle condition information around the vehicle body from the millimeter wave radars 1-4 and sends it to the vehicle system master control;

[0051] It includes a vehicle system main control 5, which receives vehicle condition information around the vehicle body from the millimeter-wave radar through the CAN network, collects vehicle information, and determines whether a safe emergency turn can be made by combining the vehicle condition information around the vehicle body and the vehicle information. If a safe emergency turn can be made, a safe turning obstacle avoidance path is generated, and a steering control signal is generated according to the turning obstacle avoidance path conversion and sent to the steering control module 6;

[0052] It includes a steering control module 6, which controls the steering wheel of the vehicle to perform emergency steering according to the steering control signal sent by the vehicle system main control 5 to prevent rear-end collision.

[0053] The millimeter wave radar 1-4 at the rear of the vehicle body detects the longitudinal distance between the vehicle and the following vehicle toward the rear. In this way, the anti-rear-end collision system is arranged on the vehicle, and the millimeter wave radar 1 arranged at the rear of the vehicle body detects the longitudinal distance between the vehicle and the following vehicle.

[0054] In a specific implementation, the millimeter wave radar arranged in front of the vehicle body can detect the longitudinal distance and lateral distance between the vehicle and the vehicle in front. The longitudinal distance is the distance along the driving direction, and the lateral distance is the distance perpendicular to the driving direction.

[0055] The present invention is aimed at the situation that the host vehicle and the following vehicle are traveling forward and backward along the same route, and the following vehicle is traveling close to the host vehicle.

[0056] The vehicle condition information around the vehicle includes the current distance and relative speed between the vehicle and the following vehicle, and the vehicle information includes the current speed of the vehicle.

[0057] A millimeter wave radar 1-4 is arranged around the vehicle body. Specifically, a millimeter wave radar 1-4 is arranged on the front and rear sides and the left and right sides of the vehicle body.

[0058] The millimeter wave radars 1-4 installed around the vehicle recognize pedestrians, vehicles or other obstacles, thereby monitoring the surrounding vehicle conditions and sending obstacle information data to the vehicle system master 5 via the CAN network 7 in real time.

[0059] The implementation process of the present invention is as follows:

[0060] If at a certain moment, the vehicle system main control 5 finds that a collision will occur from behind based on the vehicle condition data. In this emergency situation, if the driver fails to take effective measures due to cognitive delay or improper operation, the vehicle system main control 5 will immediately determine whether it is safe to avoid collision based on the surrounding vehicle condition information obtained by the millimeter wave radar 1-4 and calculate a safe and smooth turning path ( Figure 4 ), and then reminds the driver through a warning signal, and then the system starts to monitor the driver's steering intention. Once it detects that the driver starts to turn, it starts to take over the vehicle. The system converts the path information into a steering control instruction based on the current vehicle speed and sends it to the steering control module 6 through the CAN network 7.

[0061] The steering control module 6 controls the steering wheel angle according to the given control command, so that the vehicle performs collision avoidance along the calculated steering path before the original collision point. At the same time, the vehicle system main control 5 will compare and correct the real-time vehicle path with the planned path to prevent other accidents caused by deviation from the established trajectory. After the emergency steering collision avoidance action is completed, the vehicle system main control 5 will remind the driver to take over the steering wheel again and continue normal driving.

[0062] The vehicle system main control 5 generates a steering control signal and also generates a prompt alarm message and displays it on the main console to remind the driver.

[0063] In the vehicle system main control 5, the distance D and relative speed between the current vehicle and the rear vehicle are obtained in real time through the millimeter wave radar 1, and the collision risk is identified in the following manner to determine whether there is a risk of rear-end collision:

[0064]

[0065] Where D represents the longitudinal distance between the vehicle and the following vehicle detected by the millimeter wave radar 1, V1, V rel are the speed and relative speed of the rear vehicle respectively; a1 and a2 are the preset maximum braking decelerations of the rear vehicle and the vehicle respectively; t1 and t2 are the preset system delay time and driver reaction time in the rear-end collision system respectively; d0 is the safe vehicle distance to be maintained;

[0066] If the above formula is satisfied, it is determined that a rear-end collision will not occur;

[0067] When the above formula is not satisfied, it is determined that a rear-end collision will occur and the anti-rear-end collision system will be controlled.

[0068] In the vehicle system master control 5, if it is determined that there is a risk of rear-end collision, a safe emergency turn is performed in the following manner:

[0069] If the millimeter wave radar 1 detects that there is no vehicle within the preset distance d in front of the current vehicle, the vehicle speed is accelerated to be equal to the speed V1 of the rear vehicle. Figure 2 As shown, and the longitudinal acceleration a x Satisfies the following formula:

[0070]

[0071] If the millimeter wave radar 1 detects that there is a vehicle within a preset distance d in front of the current vehicle, the current vehicle performs lane change control, such as Figure 3 As shown:

[0072] When the millimeter wave radar 1 detects that there is a vehicle within a preset distance d in front of the current vehicle, the B-spline curve is used to simulate the path planning of lane change control. The B-spline curve consists of n+1 control points P i Composition, i = 0, 1, ..., n, the B-spline curve parameterization of the steering obstacle avoidance path is:

[0073]

[0074] Where k is the degree of the B-spline curve, that is, the number of control points minus 1; N i,k() is the k-order B-spline curve basis function; i represents the ordinal number of the control point, P i represents the coordinates of the i-th control point; C(u) represents the coordinates of the steering obstacle avoidance path;

[0075] Finally, the implementation options are as follows Figure 4 The quintic B-spline curve with six control points is used to plan the steering obstacle avoidance path. The quintic B-spline curve is used. These parameters are all parameters to be optimized and are used to set the positions of the control points. The steering obstacle avoidance path is planned using the quintic B-spline curve, where the coordinates of each control point P i That is:

[0076]

[0077] Wherein, L is the lane width, θ represents the curvature of the turning path for obstacle avoidance, d1, d2, d3, and d4 represent the spacing between the first pair of adjacent control points along the vehicle's driving direction, the spacing between the second pair of adjacent control points along the vehicle's driving direction, the spacing between the third pair of adjacent control points along the vehicle's driving direction, and the spacing between the fourth pair of adjacent control points along the vehicle's driving direction, respectively; in specific implementation, d1, d2, d3, and d4 are all greater than or equal to 0, and the angle θ needs to be greater than 0 and less than 90°;

[0078] At the same time, when the vehicle is driving along the steering obstacle avoidance path, the curvature ρ is calculated in real time according to the following formula:

[0079]

[0080] in, and are the first-order derivatives of the coordinates C(u) of the steering obstacle avoidance path about the x-axis and y-axis, respectively. and The coordinates C(u) of the steering obstacle avoidance path are the second-order derivatives about the x-axis and y-axis. The continuity of the path curvature requires that the B-spline curve is second-order continuous.

[0081] Then, the lateral acceleration a of the car when changing lanes is obtained according to the curvature ρ obtained in real time. y And sent to the vehicle system master 5 for acceleration control:

[0082]

[0083] Among them, V2 represents the current speed of the vehicle.

[0084] If the vehicle speed is accelerated to be equal to the speed V1 of the rear vehicle and there is still a risk of being rear-ended, the path planning of lane change control is also performed in the above manner.

[0085] Therefore, the present invention addresses the problem that current intelligent driving safety systems ignore the risk of rear-end collisions from vehicles behind, and avoids accidents in which a small car in the middle position is crushed due to a violent collision by large vehicles behind it when there are large vehicles both behind and behind it. Alarm and emergency steering measures are used to reduce or avoid such risks.

Claims

1. A rear-end collision warning method, characterized in that: Method: Using anti-rear-end collision system: It includes a millimeter wave radar, which is arranged around the vehicle body, detects and obtains vehicle condition information around the vehicle body, and sends it to the vehicle body CAN network (7); It includes a vehicle body CAN network (7), which receives vehicle condition information around the vehicle body from the millimeter wave radar and sends it to the vehicle system master control; The vehicle system main control (5) receives vehicle condition information around the vehicle body from a millimeter-wave radar through a CAN network, collects vehicle information, and determines whether a safe emergency turn can be made by combining the vehicle condition information around the vehicle body and the vehicle information. If a safe emergency turn can be made, a safe turning obstacle avoidance path is generated, and a turning control signal is generated according to the turning obstacle avoidance path conversion and sent to a turning control module (6); It includes a steering control module (6) which controls the steering wheel of the vehicle to perform emergency steering according to a steering control signal sent by the vehicle system main control (5) to prevent rear-end collision; In the vehicle system main control (5), the distance D and relative speed between the current vehicle and the rear vehicle are obtained in real time through the millimeter wave radar, and the collision risk is identified in the following manner to determine whether there is a risk of rear-end collision: Where D is the longitudinal distance between the vehicle and the following vehicle detected by the millimeter wave radar, V1, V rel are the speed and relative speed of the rear vehicle respectively; a1 and a2 are the preset maximum braking decelerations of the rear vehicle and the vehicle respectively; t1 and t2 are the preset system delay time and driver reaction time in the anti-rear-end collision system respectively; d0 is the safe vehicle distance to be maintained; If the above formula is satisfied, it is determined that a rear-end collision will not occur; When the above formula is not satisfied, it is determined that a rear-end collision will occur, and the anti-rear-end collision system will be controlled; In the vehicle system master control (5), if it is determined that there is a risk of rear-end collision, a safe emergency turn is performed in the following manner: If the millimeter-wave radar detects that there is no vehicle within the preset distance d in front of the current vehicle, the vehicle speed will be accelerated to the speed V1 equal to the speed of the vehicle behind, and the longitudinal acceleration a x Satisfies the following formula: If the millimeter-wave radar detects a vehicle within a preset distance d in front of the current vehicle, the current vehicle will perform lane change control: If the millimeter-wave radar detects that there is a vehicle within a preset distance d in front of the current vehicle, the B-spline curve simulation is used to plan the path for lane change control.

2. The rear-end collision warning method according to claim 1, characterized in that: The B-spline curve consists of n+1 control points P i Composition, i = 0, 1, ..., n, the B-spline curve parameterization of the steering obstacle avoidance path is: Where k is the degree of the B-spline curve, N i，k () is the k-order B-spline curve basis function; i represents the ordinal number of the control point, P i represents the coordinates of the i-th control point; C(u) represents the coordinates of the steering obstacle avoidance path; The quintic B-spline curve is selected to plan the steering obstacle avoidance path with the quintic B-spline curve, where the coordinates of each control point P i That is: Wherein, L is the lane width, θ represents the turning curvature of the turning obstacle avoidance path, d1, d2, d3, and d4 represent the spacing between the first pair of adjacent control points along the vehicle driving direction, the spacing between the second pair of adjacent control points along the vehicle driving direction, the spacing between the third pair of adjacent control points along the vehicle driving direction, and the spacing between the fourth pair of adjacent control points along the vehicle driving direction, respectively; At the same time, when the vehicle is driving along the steering obstacle avoidance path, the curvature ρ is calculated in real time according to the following formula: in, and are the first-order derivatives of the coordinates C(u) of the steering obstacle avoidance path about the x-axis and y-axis, respectively. and is the second-order derivative of the coordinate C(u) of the steering obstacle avoidance path with respect to the x-axis and y-axis; Then, the lateral acceleration a of the car when changing lanes is obtained according to the curvature ρ obtained in real time. y And sent to the vehicle system master control (5) for acceleration control: Among them, V2 represents the current speed of the vehicle.

3. The rear-end collision warning method according to claim 1, characterized in that: The millimeter-wave radar at the rear of the vehicle faces backward to detect the longitudinal distance between the vehicle and the following vehicle.

4. The rear-end collision warning method according to claim 1, characterized in that: There is a millimeter-wave radar installed around the vehicle body.

5. The rear-end collision warning method according to claim 1, characterized in that: The vehicle system main control (5) generates a prompt alarm message while generating a steering control signal and displays it on the main console to remind the driver.

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