CN104925057A - Automotive self-adaptive cruising system with multi-mode switching system and control method thereof - Google Patents

Abstract

The invention discloses an automobile self-adaptive cruising system with a multi-mode switching system and a control method thereof. The system is divided into a three-layer control architecture: a mode switching layer, an upper controller and a lower controller. A system is designed in the mode switching layer. A comprehensive arbitration and switching mechanism for vehicle driving modes, which is used to select the ideal working mode that is most suitable for the current driving conditions from ten control modes. The ten control modes include: constant speed cruise mode, steady-state follow-up mode, approach Front vehicle mode, rapid acceleration mode, strong deceleration mode, curve mode, lane change assist mode, collision avoidance mode, parallel mode, and cut-out mode; the upper controller is responsible for implementing the corresponding control mode and Carry out continuous processing to avoid abrupt acceleration changes; the lower controller tracks the desired acceleration by controlling the vehicle's actuators. The invention adopts a multi-mode switching system, which is more suitable for complex driving environments and improves the driver's acceptance.

Description

A car adaptive cruise system with multi-mode switching system and its control method

technical field

The invention relates to an automobile driver assistance system, in particular to an automobile self-adaptive cruise system and a control method thereof which have ten control modes and can adapt to complex driving modes and typical driver characteristics.

Background technique

As a typical representative of automotive driver assistance systems, adaptive cruise control (ACC) relies on on-board information sensors to obtain road traffic information ahead, and carries out corresponding vehicle longitudinal automatic driving control based on the movement of road objects, so it can replace the driver's Accelerator and brake operation. So far, the ACC system has gone through three stages of development: the first stage is mainly aimed at the simple highway environment, and only has the basic functions of maintaining a safe distance between vehicles and constant speed cruise. In the second stage, the working range of ACC can be extended to urban low-speed mode, with the function of automatic stop and go. In the third stage, an enhanced ACC system that can perform multi-objective optimization at the same time appeared, which can take into account safety, economy and comfort in terms of performance, and began to be integrated into electric vehicles.

However, the existing ACC system is still limited to the field of longitudinal control of the car. When the car is in the curve mode, lane change assist mode, and line mode, the ACC function will fail, which greatly affects the driver's understanding of ACC. Acceptance of technology. Therefore, it is necessary for the ACC system not only to be applicable to the steady-state straight-line driving mode, but also to have certain adaptability to transient modes such as lane changes and curves.

In order to improve the robustness of the ACC system to the complex driving environment, many scholars try to solve it by multi-mode switching, and have achieved preliminary results. Canale et al. from Plito Polytechnic University in Italy defined ACC as three modes of acceleration/constant speed/deceleration according to the motion state of the preceding vehicle, and incorporated the driver reference model into the algorithm. Fancher of the University of Michigan in the United States divides the ACC mode into three areas by using the relative vehicle distance-relative vehicle speed relationship, so as to determine which control form the car applies: speed control/time distance control/collision avoidance control. Zhang Dezhao of Tsinghua University divided ACC into four modes: constant speed cruise, distance maintenance, approaching the vehicle in front and overtaking based on the zero-expected acceleration curve. Volvo Corporation of Sweden defines five functions of ACC, which are approaching the vehicle in front, rear-end collision avoidance, acceleration following, deceleration following and merging. K.Yi et al. from Seoul National University in South Korea proposed an ACC system with lane change support function, including the following control modes: steady-state car following, steering avoidance, steering avoidance + light braking, emergency braking. The four control modes can be converted to each other according to the actual workshop movement relationship.

Continuing this idea, it is necessary to further subdivide the control mode based on the overall framework of multi-mode switching, and propose an ACC multi-mode control method with better environmental mode adaptability, which can effectively reduce the driver's work intensity. In terms of performance, it also has more comprehensive, smarter, more coordinated and more practical features.

Contents of the invention

The technical problem to be solved by the present invention is to provide an automobile adaptive cruise system with a multi-mode switching system to improve the adaptability of the ACC system under actual complex-shaped driving parts, especially towards Expansion and breakthrough in vehicle lateral motion and transient mode. How to establish the corresponding optimized control mode and its switching mechanism under the multi-mode hierarchical framework is the key to solve the applicability of the ACC system in complex road environments.

The technical scheme that the present invention adopts for solving the problems of the technologies described above is:

An automotive adaptive cruise system with a multi-mode switching system, including a three-layer control architecture of a mode switching layer, an upper controller, and a lower controller. control mode to realize coordinated control between different ACC control modes, the upper controller is used to realize the optimal control strategy under this control mode selected by the mode switching layer, and the lower controller is used to control the vehicle engine throttle and active brake pressure to track the desired acceleration output by the upper controller.

The present invention also provides a control method for the above-mentioned automobile adaptive cruise system, comprising the following steps:

1) First, the vehicle driving mode division and mode switching mechanism are established in the mode switching layer, according to whether it is affected by the driver's steering operation, whether it is affected by the shape of the road, whether it is affected by the movement of the vehicle in front, and whether it is affected by the horizontal/vertical direction Influenced by motion, the current vehicle driving mode is divided to realize the switching of ten different ACC control modes. The ten ACC control modes are: constant speed cruise mode, steady state car following mode, approaching the vehicle in front mode, rapid acceleration mode, Strong deceleration mode, curve mode, lane change assistance mode, collision avoidance mode, parallel mode, and cut-out mode, among which, the first two are steady-state modes, and the last eight are transient modes;

2) Then, in the upper controller, realize the optimal control strategy under the control mode selected by the mode switching layer;

3) Finally, in the lower controller, the desired acceleration output by the upper controller is achieved by adjusting the engine throttle and active brake pressure.

According to the above scheme, in the process of switching between the two control modes, in order to ensure the continuity of the vehicle acceleration output, before outputting the expected acceleration, the weighted average of the expected acceleration is used for continuous processing, specifically:

a _{w_des} = w ₁ · a _{w_last} + w ₂ · a _{w_next}

In the formula, a _{w_last} and a _{w_next} are the expected acceleration calculated respectively in the existing control mode and the control mode to be entered, a _{w_des} is the output of the upper controller in the transition region of the two control modes, w ₁ and w ₂ are weight coefficient, and w ₁ +w ₂ =1.

According to the above-mentioned scheme, the described cruise control mode is based on the closed-loop control of the vehicle speed. By inquiring about two throttle opening tables, the accelerator throttle lookup table and the constant speed throttle lookup table, supplemented by incremental PID control correction, the actual Keep the vehicle speed at the set speed ±1km/h.

According to the above scheme, the calculation formula of the expected acceleration under the described steady-state following mode is:

-0.3≤a _d (t)≤0.3m/s ²

In the formula, R _d (t) is the expected vehicle distance, which is related to the expected time distance set by the driver; R(t) is the relative vehicle distance; k _f ( ) is the acceleration gain coefficient; λ _f is the distance error and The weight ratio of speed error; v _p is the speed of the front vehicle; v is the speed of the vehicle.

According to the above scheme, the formula for calculating the expected acceleration under the approaching the preceding vehicle mode is:

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}$

a _d ≥ -2m/s ²

In the formula, k _a is the deceleration gain coefficient; v _r is the relative speed of the ego vehicle and the front vehicle (the meanings of other parameters are the same as above).

According to the above scheme, the calculation formula of the expected acceleration under the described rapid acceleration mode is:

a _d (t)=k _g (v(t))·(v _p (t)-v(t))

a _d (t)≤1.5m/s ²

In the formula, k _g ( ) is the acceleration gain coefficient in this mode;

Similarly, the formula for calculating the expected acceleration in the strong deceleration mode is:

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; )</span>}$

a _d ≥ -4m/s ²

In the formula, k _s is the deceleration gain coefficient, which reflects the relationship between the degree of danger of car following and the deceleration intensity; R _min is the minimum collision avoidance distance in the collision avoidance mode and the strong deceleration mode, and the calculation formula of the minimum collision avoidance distance is :

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}}$

In the formula, t _r is the driver’s collision avoidance reaction time; a _max is the maximum braking deceleration that can be provided under the current road surface adhesion conditions;

The formula for calculating the desired longitudinal acceleration in the collision avoidance mode is:

a _d =a _max

Once the relative distance is less than the minimum collision avoidance distance, it will immediately enter the collision avoidance mode, and the car will perform emergency braking at the maximum deceleration a _max until it stops (at the same time, ABS will intervene to prevent the wheels from locking if necessary).

According to the above scheme, the formula for calculating the desired longitudinal acceleration in the curve mode is:

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}$

In the formula, a _d is the lateral acceleration of the vehicle, K _xy and T _xy are the longitudinal and lateral coupling coefficient and delay time respectively.

According to the above scheme, the distance between the self-vehicle and the vehicles before and after the target lane in the predicted time should satisfy the following relationship in the lane-changing assistance mode:

(x _i (t)-x ₀ (t)) ² +(y _i (t)-y ₀ (t)) ² ≥ R _min

In the formula, (x ₀ , y ₀ ) and ( _xi , y _i ) are the absolute coordinate positions of the ego vehicle and the target vehicle at the prediction time in the earth coordinate system respectively.

According to the above-mentioned scheme, the described merging mode is to predict its merging intention according to the lateral displacement and the lateral speed of the vehicle in the side lane relative to the center line of the own vehicle lane, and to switch the following target in time; under the described cut-out mode According to the lateral displacement and lateral velocity of the front vehicle in the own vehicle lane relative to the center line of the own vehicle lane, the possibility of its driving out of the own vehicle lane is predicted, and the target switching of the following vehicle is performed in time.

Compared with the prior art, the present invention has the following main advantages:

1. On the basis of the original multi-mode adaptive cruise system of automobiles, aiming at the functional limitations in the transient mode, a mode switching layer is added on top of the original upper-layer controller, which integrates environmental vehicles, road information and driving intentions. Coordinated control between ten control modes is realized, and the determined ten control modes and their switching mechanisms are more in line with the actual ACC driving mode, improving the driving safety, ride comfort and driver comfort of the car in automatic driving. Receptivity;

2. Relying on the multi-mode switching control system, focusing on solving the problems of poor applicability of the adaptive cruise system in complex environments and insufficient driver acceptability, especially improving the driver's acceptance of the system in transient modes such as lane changes and curves , making the system more adaptable to the complex driving environment.

Description of drawings

Fig. 1 is a schematic diagram of the control structure of the automobile multi-mode adaptive cruise system of the present invention.

Fig. 2 is a schematic diagram of the mode division of the multi-mode adaptive cruise system of the automobile according to the present invention.

Fig. 3 is a schematic diagram of longitudinal driving mode switching of the multi-mode adaptive cruise system of an automobile according to the present invention.

Fig. 4 is a schematic diagram of the switching of the curve driving mode of the automobile multi-mode adaptive cruise system of the present invention.

FIG. 5 is a schematic diagram of lane-changing driving mode switching of the multi-mode adaptive cruise system of an automobile according to the present invention.

Fig. 6 is a schematic diagram of the control principle of the constant speed cruise mode of the multi-mode adaptive cruise system of the automobile according to the present invention.

Detailed ways

The present invention will be described in further detail below based on specific embodiments and in conjunction with the accompanying drawings.

With reference to shown in Fig. 1, the automobile adaptive cruise system with multi-mode switching system of the present invention adopts a three-layer control structure, and in the mode switching layer, selects the corresponding desired control mode according to the current driving mode of the automobile; In the upper-level controller, the optimal control strategy in this mode is specifically implemented; in the lower-level controller, the desired acceleration is tracked through the joint control of the throttle/brake.

The comprehensive arbitration and switching mechanism of ACC driving mode is the core content in the mode switching layer, which needs to comprehensively consider factors such as environmental vehicles, road information, and driving intentions. Figure 2 shows a complete set of vehicle driving mode division methods. Effective division of vehicle driving modes is a prerequisite for realizing ACC control mode switching. Therefore, the present invention combines the identification of driver's manipulation intention and sensor information fusion technology to divide complex driving modes and establish a complete set of mode arbitration and switching mechanism. Among them, the current vehicle driving mode is divided according to whether it is affected by the driver's steering operation, whether it is affected by the shape of the road, whether it is affected by the movement of the vehicle in front, and whether it is affected by the lateral/longitudinal movement. Ten control modes are defined. Figures 3 to 5 show the coordinated switching mechanisms between different modes. Reasonable mode switching logic is the control basis for realizing multi-mode ACC.

Because the mode switching process often leads to sudden changes in vehicle acceleration, it is not conducive to ride comfort. Therefore, it is necessary to use the weighted average algorithm to continuously process the expected acceleration, as shown in the following formula:

a _{w_des} = w ₁ · a _{w_last} + w ₂ · a _{w_next}

In the formula, a _{w_last} and a _{w_next} are the expected acceleration calculated respectively in the existing control mode and the control mode to be entered, a _{w_des} is the output of the upper controller in the transition region of the two control modes, w ₁ and w ₂ are weight coefficient, and w ₁ +w ₂ =1.

The automobile multi-mode self-adaptive cruise system provided by the present invention defines ten kinds of control modes in total, which are explained respectively below:

(1) Cruise control mode

When there is no effective target within the detection range of the vehicle lane in front, the system enters the constant speed cruise mode. By comparing the expected vehicle speed set by the driver with the actual vehicle speed obtained from the feedback of the wheel speed sensor, it is hoped that the vehicle speed will be kept as close to the set speed as possible. Within ±1km/h. The key of the constant speed cruise mode is to quickly determine the required throttle opening value when the vehicle is accelerating or driving at a constant speed according to the two expected throttle lookup tables (acceleration throttle lookup table, constant speed throttle lookup table) in Figure 6 . Different from several other control modes, the cruise control mode is a closed-loop control based on the vehicle speed, so it can directly obtain the throttle opening without designing the lower controller, and at the same time, it can be fine-tuned and corrected by incremental PID control.

(2) Steady state following mode

As one of the most commonly used ACC control modes, the steady-state following mode has the characteristics of small relative speed and small acceleration. At this time, the relative speed of the self-vehicle and the vehicle in front is very small, and the relative distance between vehicles is also near the safe distance. Therefore, the A linear car-following structure determines the expected acceleration so that the steady-state errors of the vehicle distance and vehicle speed converge to 0 at the same time. The calculation formula is:

a _d (t)＝k _f (v(t))·[(v _p (t)-v(t))+λ _f ·(R _d (t)-R(t))]

At the same time, considering the comfort of the longitudinal ride and the fuel economy of the vehicle, it is hoped that the vehicle acceleration will change smoothly, and the desired acceleration will be saturated, as shown in the following formula:

-0.3≤a _d (t)≤0.3m/s ²

In the formula, R _d (t) is the expected vehicle distance, which is related to the expected time distance set by the driver; R(t) is the relative vehicle distance; k _f ( ) is the acceleration gain coefficient; λ _f is the distance error and The weight ratio of the speed error; v _p is the speed of the front vehicle; v is the speed of the vehicle.

(3) Approaching the vehicle in front mode

The mode of approaching the vehicle in front is often used in the mode where the ego vehicle approaches the slow vehicle in front from a long distance. At this time, the absolute value of the initial relative speed v _r of the two vehicles is relatively large, and the initial distance is much greater than the safe distance between vehicles. In order to finally transition to the steady-state following mode smoothly, the expected acceleration obtained needs to conform to the uniform deceleration characteristics of the driver, and the calculation formula is as follows:

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; \&Greater\; Equal;</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

In the formula, k _a is the deceleration gain coefficient; v _r is the relative speed of the ego vehicle and the front vehicle, and the meanings of other parameters are the same as above.

(4) Rapid acceleration mode

In the rapid acceleration mode, since there is no risk of rear-end collision, the driver can often tolerate a large tracking error, and the requirements for tracking performance should be relaxed; at the same time, considering that the rapid acceleration process of the vehicle will deteriorate fuel economy and reduce ride comfort The desired acceleration needs to be saturated, and the calculation formula is as follows:

a _d (t)＝k _g (v(t))·(v _p (t)-v(t)) a _d (t)≤1.5m/s ²

In the formula, k _g (·) is the acceleration gain coefficient in this mode, and the meanings of other parameters are the same as above.

(5) Strong deceleration mode

In the strong deceleration mode, focus on how to achieve driving safety. At this time, the relative speed of the two vehicles is negative, and the inter-vehicle distance is also smaller than the safe inter-vehicle distance. The determined expected acceleration should conform to the driver’s strong braking characteristics. The calculation formula is as follows :

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; min</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; \&Greater\; Equal;</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

In the formula, k _s is the deceleration gain coefficient, which reflects the relationship between the degree of danger of car following and the intensity of deceleration; R _min is the minimum collision avoidance distance in collision avoidance mode and strong deceleration mode.

(6) Collision avoidance mode

The collision avoidance mode has the highest control priority. In addition to the vehicle in front, the collision avoidance targets also include various stationary or near-stationary obstacles such as pedestrians, guardrails, trees, etc.; Emergency braking at speed until a complete stop; since the purpose of collision avoidance mode is to completely avoid collision or reduce collision damage, no restriction will be imposed on the acceleration, the calculation formula is as follows:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}}$

In the formula, t _r is the driver's reaction time for collision avoidance; a _max is the maximum braking deceleration that can be provided under the current road surface adhesion conditions, and the meanings of other parameters are the same as above.

(7) Curve mode

In the curve mode, there is a certain coupling relationship between the vehicle’s longitudinal acceleration and its lateral acceleration. The first-order lag model is used to describe it mathematically. The gain coefficient and delay time are K _xy and T _xy respectively. The calculation formula is as follows:

${\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; y</span>}}$

In the formula, a _y is the lateral acceleration of the vehicle, K _xy and T _xy are the longitudinal and lateral coupling coefficients and delay time, respectively.

Since the lateral acceleration in the above formula will be affected by the shape of the road, the change law of the longitudinal acceleration essentially depends on the change rate of the curvature of the curve.

(8) Lane change assist mode

The lane change assist mode usually occurs when the speed of the vehicle in front is slow, and the driver hopes to trade space for time, so that the vehicle can gain a greater speed advantage after changing lanes. In the lane change assist mode, it is necessary to consider whether there will be a collision with the front and rear vehicles in the target lane. Therefore, by predicting the geodetic coordinates of the ego vehicle and the target vehicle within the prediction time, it can be judged whether the lane changing operation is safe and feasible. The trajectory interval between two vehicles in lane change should conform to the following relationship:

(x _i (t)-x ₀ (t)) ² +(y _i (t)-y ₀ (t)) ² ≥ R _min

In the formula, (x ₀ , y ₀ ) and ( _xi , y _i ) are the absolute coordinate positions of the ego vehicle and the target vehicle at the prediction time in the earth coordinate system respectively, and the meanings of other parameters are the same as above.

(9) Parallel mode

In the merging mode, it is necessary to consider the possibility of merging vehicles in the side lane and switch the following target in a timely manner. The size of the intention, choose the appropriate main target in the two vehicles. A look-up table for predicting the merging intention is established by using the lateral displacement of the merging vehicle in the side lane relative to the center line of the own vehicle lane and the weight relationship of the lateral velocity. If the merging probability obtained by looking up the table is less than the minimum merging threshold, select the vehicle in the vehicle lane as the main target; if the merging probability is greater than the maximum merging threshold, select the merging vehicle as the main target; if the probability is between the two thresholds , it is necessary to integrate the motion states of the two vehicles, and take the result of weighted processing as the main goal.

(10) Cut out mode

Similar to the merging mode, the cut-out mode also improves the real-time performance of the target update by predicting the possibility of the vehicle in front of the target driving out of the vehicle lane. Using the weight relationship of the lateral displacement of the target vehicle relative to the centerline of the lane and the lateral velocity, a rule table for predicting the cutting intention of the vehicle in front is established. If the cut-out probability obtained by looking up the table is less than a certain threshold, the existing car-following target is still maintained; otherwise, the current tracking target is discarded, and a new target vehicle ahead is re-identified in the own vehicle lane.

Apparently, the above-mentioned embodiments are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And these obvious changes or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims (10)

1. one kind has the automotive self-adaptive cruise system that multi-mode switches system, it is characterized in that, comprise pattern switchable layer, top level control device, lower floor's controller three layers controls framework, described pattern switchable layer is used for combined environment vehicle, road information and driving intention, the master mode that coupling is expected, realize the cooperation control between different ACC master mode, described top level control device is used for the optimal control policy under this kind of master mode of implementation pattern switchable layer selection, described lower floor controller is used for the expectation acceleration/accel following the tracks of the output of top level control device by controlling automotive engine throttle and active brake-pressure.

2. a control method for automotive self-adaptive cruise system according to claim 1, is characterized in that, comprise the steps:

1) first, establish car travel mode at pattern switchable layer to divide and pattern handover mechanism, according to the impact whether being subject to Driver Steering Attention, whether be subject to the impact of road shape, whether be subject to the impact of front truck motion and what be subject to is the impact of transverse direction/longitudinal movement, current running car pattern is divided, realize the switching of ten kinds of different ACC master modes, ten kinds of ACC master modes are respectively: cruise pattern, stable state Car following model, close to front truck pattern, anxious aero mode, strong deceleration mode, bend pattern, change auxiliary mode, collision avoidance pattern, doubling pattern, cut out pattern, wherein, first two is equilibrium mode, latter eight kinds is transient mode,

2) then, in top level control device, the optimal control policy under this kind of master mode that implementation pattern switchable layer is selected;

3) last, in lower floor's controller, the expectation acceleration magnitude realizing top level control device by regulating engine air throttle and initiatively brake-pressure and export.

3. the control method of automotive self-adaptive cruise system according to claim 2, it is characterized in that, carry out in the process switched two kinds of master modes, in order to ensure the continuity that vehicle acceleration exports, before acceleration/accel is expected in output, take weighted mean to carry out continuity process to expectation acceleration/accel, be specially:

a _{w_des}＝w ₁·a _{w_last}+w ₂·a _{w_next}

In formula, a _{w_last}with a _{w_next}for the expectation acceleration/accel that existing master mode and the master mode that is about to enter calculate respectively, a _{w_des}for the output of top level control device in two kinds of master mode transitional regions, w ₁with w ₂for weight coefficient, and w ₁+ w ₂=1.

4. the control method of automotive self-adaptive cruise system according to claim 2, it is characterized in that, described cruise pattern is the closed loop control based on the speed of a motor vehicle, by inquiry acclerating section valve question blank, at the uniform velocity throttle gate question blank two throttle opening tables, be aided with incremental timestamp to correct, actual vehicle speed is remained near the setting speed of a motor vehicle ± 1km/h.

5. the control method of automotive self-adaptive cruise system according to claim 2, is characterized in that, the computing formula of the expectation acceleration/accel under described stable state follow the mode is:

-0.3≤a _d(t)≤0.3m/s ²

In formula, R _dt () is for expecting spacing, relevant with the desired time headway size that chaufeur sets; R (t) is relative spacing; k _f() is acceleration gain coefficient; λ _ffor the weight ratio of distance error and speed course latitude error; v _pfor front vehicle speed; V is from the car speed of a motor vehicle.

6. the control method of automotive self-adaptive cruise system according to claim 5, is characterized in that, the described computing formula close to the expectation acceleration/accel under front truck pattern is:

$a_d=k_a\&CenterDot;\frac{v_r^2}{2\&CenterDot;(R-R_d)}$

a _d≥-2m/s ²

In formula, k _afor deceleration/decel gain factor; v _rfor from the relative speed of a motor vehicle of car with front truck.

7. the control method of automotive self-adaptive cruise system according to claim 5, is characterized in that, the computing formula of the expectation acceleration/accel under described anxious aero mode is:

a _d(t)＝k _g(v(t))·(v _p(t)-v(t))

a _d(t)≤1.5m/s ²

In formula, k _g() is the acceleration gain coefficient under this pattern;

Similar, the computing formula of the expectation acceleration/accel under described strong deceleration mode is:

$a_d=k_s\&CenterDot;\frac{v_r^2}{2\&CenterDot;(R-R_{min})}$

a _d≥-4m/s ²

In formula, k _sfor deceleration/decel gain factor, reflect with the relation between car hazard level and deceleration intensity; R _minfor the minimum collision avoidance distance under collision avoidance pattern and strong deceleration mode, the computing formula of minimum collision avoidance distance is:

$R_{min}=(v\left(t\right)-v_p\left(t\right))\&CenterDot;t_r+\frac{v^2\left(t\right)-v_p^2\left(t\right)}{2a_{max}}$

In formula, t _rfor the chaufeur collision avoidance reaction time; a _maxfor the maximum braking deceleration that can provide under current road attachment condition;

Expect under described collision avoidance pattern that the computing formula of longitudinal acceleration is:

a _d＝a _max

Once spacing is less than minimum collision avoidance distance relatively, can enter collision avoidance pattern immediately, automobile is with maximum deceleration a _maxcarry out emergency braking until stop and stop.

8. the control method of automotive self-adaptive cruise system according to claim 2, is characterized in that, expects that the computing formula of longitudinal acceleration is under described bend pattern:

$a_d=-\frac{K_{xy}}{1+T_{xy}s}{\stackrel{\&CenterDot;}{a}}_y$

In formula, a _yfor automobile side angle acceleration/accel, K _xy, T _xybe respectively longitudinal and lateral coupling coefficient and delay time.

9. the control method of automotive self-adaptive cruise system according to claim 7, is characterized in that, described changes under auxiliary mode that the location gap in predicted time should meet following relational expression from car and target track fore-aft vehicle:

(x _i(t)-x ₀(t)) ²+(y _i(t)-y ₀(t)) ²≥R _min

In formula, (x ₀, y ₀) and (x _i, y _i) be the absolute coordinates position of predicting the moment from car and target vehicle under geodetic coordinate system respectively.

10. the control method of automotive self-adaptive cruise system according to claim 2, it is characterized in that, predict that its doubling is intended to according to other track vehicle relative to from the cross travel of car track line of centers and cross velocity under described doubling pattern, and carry out in time switching with car target; Predict that it rolls the possibility from car track away from according to from car track front truck relative to from the cross travel of car track line of centers and cross velocity under the described pattern that cuts out, and carry out in time switching with car target.