KR100906667B1 - System for Automatic Controlling Longitudinal Speed of a Vehicle - Google Patents

Abstract

In a vehicle crash situation, a system is introduced that can automatically control the longitudinal vehicle speed of a vehicle with similar acceleration to the driver. The system includes a vehicle speed sensor; A radar sensor capable of measuring a distance from a preceding vehicle; And an adapter for receiving a signal from the vehicle speed sensor and the radar sensor, calculating a collision warning index (x) and a reverse collision time (TTC- ¹ ), calculating a target acceleration from these, and controlling the vehicle speed according to the target acceleration. Cruise control unit; includes.

Longitudinal, vehicle speed control, adaptive cruise control

Description

System for Automatic Controlling Longitudinal Speed of a Vehicle}

The present invention relates to an automatic longitudinal vehicle speed control system, and more particularly to a system capable of automatically controlling the longitudinal vehicle speed of a vehicle with an acceleration similar to that of a driver in a vehicle crash situation.

In order to enhance the convenience of the driver and prevent accidents, the development of intelligent driving assistance / safety control systems has been actively conducted.

The intelligent driving assistance / safety control system uses adaptive cruise control technology, and the driving control of the vehicle based on the adaptive cruise control can secure a safe distance from the vehicle ahead and prevent accidents. .

However, the vehicle control using the conventional adaptive cruise control is made in such a way as to decelerate the vehicle uniformly with an acceleration that can avoid a collision depending on the relative distance to the preceding vehicle, so that the timing and the degree of vehicle control are familiar to the driver. There is a problem that causes anxiety.

The present invention has been proposed to solve such a problem, and provides a longitudinal vehicle speed automatic control system for controlling the vehicle with acceleration similar to the driver in a vehicle crash situation by making data of the driver's response according to various driving conditions. There is this.

A longitudinal vehicle speed automatic control system according to the present invention for achieving the above object, the vehicle speed sensor; A radar sensor capable of measuring a distance from a preceding vehicle; And an adaptive cruise that receives signals from the vehicle speed sensor and the radar sensor, calculates a collision alarm index (x) and a reverse collision time (TTC- ¹ ), calculates a target acceleration from these, and controls the vehicle speed according to the target acceleration. And a control unit.

The collision alarm index x is represented by the following equation.

Here, C is the initial distance from the preceding vehicle, D _b is the relative moving distance between the preceding vehicle and the control vehicle during braking considering the mechanical delay of the control vehicle, D _w is a predetermined alarm distance in consideration of the human delay in D _b .

Preferably, the adaptive cruise control unit calculates a target acceleration by using a map in which the first target acceleration with respect to the collision warning index is matched and the second target acceleration with respect to the reverse collision time is matched, but the The target acceleration is calculated by differently assigning weights to the first target acceleration and the second target acceleration according to the current vehicle speed.

Also preferably, the adaptive cruise control unit assigns a high weight to the second target acceleration in the high-speed section and a high weight to the first target acceleration in the low-speed section based on the preset reference vehicle speed.

Also preferably, the map may include a collision warning index (x) and a reverse collision time (TTC ⁻ ) at a time when the occupant of the trailing vehicle feels dangerous through a number of experiments that rapidly decelerate the preceding vehicle in various steps. ¹ ) and deceleration data of the following vehicle.

Also preferably, the map reflects the risk that the occupant of the trailing vehicle feels according to the deceleration speed of the trailing vehicle in each driving situation in the experiments.

According to the longitudinal vehicle speed automatic control system having the above-described structure, the driver's response method according to various driving conditions can be made into data by using the collision warning index and the reverse collision time as variables, and the vehicle collision situation can be used by using such data. In this way, it is possible to control the longitudinal speed of the vehicle with acceleration similar to that of the driver.

Hereinafter, with reference to the accompanying drawings looks at with respect to the longitudinal vehicle speed automatic control system according to a preferred embodiment of the present invention.

As shown in FIG. 1, the automatic control system is largely comprised of a vehicle speed sensor, a radar sensor, and an adaptive cruise control unit.

The vehicle speed sensor is a conventional wheel sensor, and the radar sensor may be a radar radio wave use sensor commonly used in adaptive cruise control. The radar sensor measures the distance between the preceding vehicle and the control vehicle to calculate the speed of the preceding vehicle.

The adaptive cruise control unit typically controls the vehicle so as to maintain a constant distance between the preceding vehicle when the preceding vehicle is present and performs a constant speed driving when the preceding vehicle is absent. In particular, The vehicle receives the signals from the vehicle speed sensor and the radar sensor, calculates the collision warning index (x) and the reverse collision time (TTC- ¹ ), calculates the target acceleration from them, and controls the vehicle speed according to the target acceleration in the collision situation. . The adaptive cruise control unit is connected to an engine control unit (ECU) and an electronic stability control (ESC) unit for controlling throttle and brake.

The collision alarm index (x) and the reverse collision time (TTC ^-1 ) will be described with reference to FIGS. 2 and 3.

First, the collision alarm index x is defined by Equation 1 below.

[Equation 1]

Here, C is the initial distance from the preceding vehicle, D _b is the relative moving distance between the preceding vehicle and the control vehicle during braking considering the mechanical delay of the control vehicle, D _w is a predetermined alarm distance in consideration of the human delay.

Looking at the method of calculating the collision alarm index (x) with reference to Figure 2, as shown in Figure 2, while the following vehicle is normally following the preceding vehicle, the preceding vehicle decelerates rapidly and accordingly the following vehicle is rapidly decelerated In this case, D _b is calculated as in Equation 2 below.

[Formula 2]

Here, Vs is a mechanical delay time such as a following vehicle speed, Vp is a preceding vehicle speed, a _s is a deceleration speed of a following vehicle, a _p is a deceleration speed of a preceding vehicle, and T ₁ is a reaction speed of a brake relay. It can also be set to the maximum deceleration of the a _s and a _p vehicles (appeared to range from about -8 to 10 kHz).

The initial distance C of the preceding vehicle and the following vehicle, the final distance C ′ after deceleration, and D _b have a relationship of Equation 3 below.

[Equation 3]

C '= C-D _b

The alarm distance D _w is an alarm distance set in consideration of a human delay in order to avoid a vehicle collision, and is a delay distance due to a time difference from a human recognition point to an action point at which a brake is applied to D _b . When D _b and D _w are expressed as terms commonly used as input values in the adaptive control unit, Equation 4 below may be used.

[Equation 4]

Here, t _{system - delay} corresponds to t1, t _{human - delay} is the human delay time, f (μ) is the friction force between the surface and the wheel of the vehicle, μ is the coefficient of friction.

On the other hand, the reverse collision time (TTC ^-1 ) is the inverse of the time until the deceleration with a constant acceleration and the preceding vehicle collides with the reverse collision time (TTC ^-1 ) is expressed in another way It may be possible, but as shown in FIG. 3, the vehicle occupant may be expressed as Equation 5 below in the form of a risk that the vehicle occupant is visually felt by the roaming effect in a crash situation.

[Equation 5]

Where w is the vehicle width, R is the distance from the occupant's position of the trailing vehicle to the preceding vehicle, θ is the viewing angle with respect to the vehicle width, and R ^° is (Vp-Vs).

A method of extracting the collision alarm index (x) and the reverse collision time (TTC- ¹ ) data will be described with reference to FIG. 4.

As shown in FIG. 4, in order to grasp the deceleration time of the driver in the sudden deceleration situation, two vehicles are repeatedly used to reproduce various driving situations in which the driver uses a large deceleration rate. In other words, a situation where a trailing vehicle follows the preceding vehicle at various speeds is constant, and the deceleration of the preceding vehicle is phased in each situation, and the vehicle decelerates without notice, and the time when the occupant of the trailing vehicle perceives anxiety / risk and Record the deceleration of the trailing vehicle. To this end, a trailing vehicle is provided with a button so that the occupant can press when aware of a danger, and a device capable of detecting the deceleration and / or the brake amount of the vehicle when the button is pressed. An example of the data of the result of such a rapid deceleration driving experiment is shown in FIG. 5.

6 and 7 are graphs showing data belonging to 5 to 95% of the corresponding data by classifying the experimental result data as the acceleration section as described above. FIG. 6 shows the relationship between the acceleration and the collision alarm index x, and FIG. 7 shows the relationship between the acceleration and the reverse collision time (TTC- ¹ ).

As shown in FIG. 6, the collision alarm index x generally maintains a value greater than or equal to '1' in the case of a> -4 μs, and shows a value smaller than '1' in the case of a <-4 μs. Overall, as the magnitude of deceleration increased, the crash alarm index tended to decrease gradually. In particular, the average value of the collision warning index in the region of deceleration of -6㎨ is about 0.13, which confirms that it can be used as an evaluation standard to secure safety in a sudden deceleration or collision avoidance situation.

As shown in FIG. 7, in the general situation in which the reverse collision time (TTC ^-1 ) is also a> -2㎨, the value is almost '0', but as the magnitude of the acceleration increases, the reverse collision time increases. Could confirm. In particular, in the area of deceleration less than -6㎨, the average value is about 1.13, and such an index range can be used as an evaluation standard for securing safety in situations where sudden deceleration or collision avoidance is required in evaluating the controller.

On the other hand, in the experiment process as described above, after the rapid deceleration driving experiment, to investigate the relationship between the vehicle deceleration and the sensitivity of the occupants, a questionnaire about the driving situation was carried out for the occupants. The questionnaire prepared five-step items with '0' for deceleration perception, '2.5' for anxiety, and '5' for high risk, and as a result, the driver's seat for deceleration as shown in Figs. The passenger's sensitivity was obtained. As shown in Figures 8 and 9, the passengers are analyzed to gradually recognize the severe anxiety and risk so that the deceleration increases.

As shown in FIG. 10, the index-based risk (index boundary between safety / risk can be set, for example, based on average values in FIGS. 6 and 7) classification and deceleration of the occupant. Risk classification using sensitivity (acceleration threshold between risk / safety, for example, may be based on 2.5 in the questionnaire above) is similar to each other. Therefore, it can be seen that it is possible to classify the risk situation using the index. However, in order to predict the dangerous situation using the index while driving the vehicle, the area between the acceleration and the index is more precisely selected, and the target acceleration / deceleration may be selected using the acceleration and the index map in such an area. It is preferable to extract.

FIG. 11 classifies the safety / hazard risks using the risk based on the index and the sensitivity of the occupant to deceleration in order to select a region in which the acceleration and the index are more accurate. Is shown. In FIG. 11, A, B, C, and D denote the number of sample data included in the corresponding area in the driving test result data. In the convergence matrix method, g _mean1 as shown in Equation 6 below is used to determine the degree of similarity between actual and predicted classification.

[Equation 6]

The larger g _{mean1 indicates} that the two classification results are _similar.In Equation 6, TP represents a correctly predicted risk situation among actual risk situations, and P represents a real risk situation ratio in the predicted risk situation. Therefore, based on the driving data according to the experimental results, each convergence matrix for a specific acceleration and a wide range of indices is obtained, and the index when g _mean1 is the maximum among these matrices best matches a specific deceleration rate. Selected by index value.

On the other hand, when the index, that is, the collision warning index (x) and the reverse collision time (TTC- ¹ ) and the acceleration (which consists of a map) is made as described above, the target acceleration is derived from the collision risk situation using the index. . However, the collision warning index responds well to dangerous conditions at high speeds, and the reverse collision time responds well to dangerous conditions at low speeds. Calculate the target acceleration. That is, as shown in Figure 12, when the vehicle speed and the distance between the control vehicle and the preceding vehicle is input, the collision alarm index (x) and the reverse collision time (TTC- ¹ ) is calculated from this, each collision using a map Obtain the first target acceleration a ₁ corresponding to the alarm index and the second target acceleration a ₂ corresponding to the reverse collision time, and weight the first and second target accelerations according to the speed of the vehicle to obtain the final target acceleration a 1. The target acceleration a _d of is calculated. In this case, the weight is given to the second target acceleration higher in the section higher than the preset reference vehicle speed, and the weight is given to the first target acceleration higher in the section lower than the reference vehicle speed, and the degree of the weight according to the reference vehicle speed and the vehicle speed is It can be derived more accurately through experiments and simulations.

1 is a schematic structural diagram of a system according to an embodiment of the present invention;

2 is a view for explaining a collision alarm index according to an embodiment of the present invention,

3 is a view for explaining a reverse collision time according to an embodiment of the present invention,

4 is a view for explaining an experimental process for deriving a collision alarm index and a reverse collision time according to an embodiment of the present invention;

5 is an example of experimental result data as in FIG. 4;

FIG. 6 is a graph illustrating a relationship between the collision warning index and the acceleration based on the experimental results as shown in FIG. 4;

FIG. 7 is a graph illustrating a relationship between the impact time of the reverse collision and the acceleration created based on the experimental results of FIG. 4 and FIG.

8 and 9 are graphs showing the relationship between the sensitivity and the acceleration of the trailing vehicle occupant based on the experimental results as shown in FIG.

FIG. 10 is a graph showing a correlation between the risk according to the acceleration and the risk according to the index, created based on the experimental results as shown in FIG. 4;

11 is a constitution matrix diagram for selecting a region where a match between acceleration and an index is more accurate according to an embodiment of the present invention;

12 is a diagram illustrating a process of calculating acceleration using a collision alarm index and a collision time according to an embodiment of the present invention.

Claims (5)

Vehicle speed sensor; A radar sensor capable of measuring a distance from a preceding vehicle; And Adaptive cruise control that receives signals from the vehicle speed sensor and the radar sensor, calculates the collision alarm index (x) and the reverse collision time (TTC- ¹ ), calculates the target acceleration from these, and controls the vehicle speed according to the target acceleration. A unit; The collision alarm index (x) is,

Where C is the initial distance from the preceding vehicle, D _b is the relative movement distance between the preceding vehicle and the control vehicle during braking considering the mechanical delay of the control vehicle, and D _w is the preset alarm distance in consideration of the human delay in D _b . Longitudinal vehicle speed automatic control system. The control vehicle of claim 1, wherein the adaptive cruise control unit calculates a target acceleration by using a map in which the first target acceleration with respect to the collision warning index is matched and the second target acceleration with respect to the reverse collision time is matched. And a target acceleration is calculated by differently assigning weights to the first target acceleration and the second target acceleration in accordance with the current vehicle speed. The method according to claim 2, wherein the adaptive cruise control unit, based on a predetermined reference vehicle speed, to give a high weight to the second target acceleration in the high-speed section, and to give a high weight to the first target acceleration in the low-speed section. Longitudinal vehicle speed automatic control system. 4. The collision warning index (x) according to claim 2 or 3, wherein the map is a collision warning index (x) at times when the occupant of the trailing vehicle feels dangerous through a number of experiments that rapidly decelerate the preceding vehicle in several steps. A longitudinal vehicle speed automatic control system, characterized in that it is built on the basis of the time (TTC- ¹ ) and the deceleration data of the following vehicle. 5. The longitudinal vehicle speed automatic control system according to claim 4, wherein the map reflects a risk that the occupant of the trailing vehicle feels according to the deceleration speed of the trailing vehicle in each driving situation in the experiments.

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