Method for controlling the braking system of a stationary or nearly stationary vehicle

Abstract

Method for controlling a vehicle's braking system to reduce the consequences of a collision with another vehicle, characterized in that (a) the speed of the vehicle is monitored, and (b) signals from environmental sensors are evaluated and (c) if the vehicle is stationary and if the evaluated signals indicate a risk of collision with a vehicle approaching from behind, the braking system is automatically triggered, wherein the evaluation of the signals from the environmental sensors consists of a comparison of the measured distance of the vehicle approaching from behind with the assumed braking distance of the rear vehicle at the determined approach speed, wherein the signal for triggering the braking system is generated when the measured distance approaches or falls below the assumed braking distance of the approaching vehicle at the measured approach speed, wherein the braking system comprises all actively controllable braking means available in the vehicle, and if it is automatically triggered in step (c), the maximum possible braking force is generated.

Description

Description

[0001] The invention relates to a method for controlling a braking system of a stationary or nearly stationary vehicle to reduce the consequences of a collision with another vehicle. State of the art

[0002] Modern vehicles are equipped with braking systems that, under certain conditions, actively generate braking force at the wheels via electrical actuation. This force is greater than, and in some cases independent of, the driver's input, as described, for example, in German patent application DE 195 24 939 C1. These braking systems can be activated by signals obtained from yaw stabilization systems or adaptive cruise control. However, these automatic braking systems require highly complex and therefore costly safety concepts to prevent unwanted and unexpected braking while driving.

[0003] German patent application DE 197 53 971 A1 discloses a method and a device for controlling a vehicle's braking system, in which, in a detected collision situation, braking force is applied beyond the driver's input, preferably up to a maximum value. This method activates the braking system only after a detected collision, and then a more or less long period of time elapses until the requested braking effect is achieved, e.g., until the brake cylinders are filled by a pump. If a vehicle collides with a stationary vehicle at high speed, the vehicle in front is accelerated sharply, leading to a high risk of injury to its occupants. Furthermore, there is a risk that the vehicle will be pushed into a dangerous area, such as an intersection or into another vehicle stopped in front of it.

[0004] German patent application DE 196 07 788 A1 discloses a parking aid that reduces engine power when reversing and automatically brakes when the distance to an obstacle is small. The invention is aimed at a moving vehicle and compares the distance to that of fixed thresholds.

[0005] The publication DE 43 26 051 A1 describes a predictive collision warning system that protects a moving vehicle from a collision with an obstacle moving ahead.

[0006] German patent application DE 197 36 840 A1 describes a method for the situation-dependent triggering of restraint systems such as airbags and seatbelt pretensioners. The system uses pre-crash sensors (e.g., distance sensors) to estimate the severity of an impending accident and to activate the restraint devices accordingly in stages.

[0007] German patent application DE 600 15 157 T2 discloses an anti-collision device in which, in the event of an impending frontal collision, a part of a bumper is swung forward by means of a propellant charge. The activation of this mechanical device is controlled by a forward-looking sensor.

[0008] The publication DE 10 2004 046 360 A1 describes a preventive protection system for a motor vehicle that controls several safety devices. The actuators are controlled based on a calculated remaining time until the collision, with a safety device being activated depending on this time.

[0009] German patent application DE 603 ​​08 593 T2 discloses a vehicle braking system that reacts to rear-end collisions. The system uses multiple rear sensors, and based on an identified collision type, the system individually controls the brakes of each wheel to generate a braking torque.

[0010] The object of the invention is to provide a straightforward method that ensures the automatic activation of the braking system of a stationary or nearly stationary vehicle in the event of a detected risk of collision with a vehicle approaching from behind. This is achieved by the feature of the independent patent claim. Advantages of the invention

[0011] The method according to the invention detects an emergency situation in which another vehicle dangerously approaches a stationary vehicle from behind, endangering the occupants of the stationary vehicle due to the impact and the resulting strong acceleration. The method according to the invention significantly reduces this acceleration because the braking system is activated before the collision. A particular advantage is that this is achieved without additional sensors or other additional equipment. It is especially advantageous that the automatic braking according to the invention is only triggered when the vehicle is stationary, thus eliminating the risk of false activations and requiring less complex safety concepts compared to known automatic braking systems.

[0012] In principle, the brake could always be activated when stationary; however, by activating it only in the event of a detected risk of collision, the rapid wear of the brake actuator is avoided. Brief description of the drawings They show: Fig. 1 a flowchart of the embodiment of the method according to the invention and Fig. 2. An exemplary system architecture for carrying out the procedure. Description of exemplary implementations

[0013] The vehicle is usually held at a standstill by the driver's pedal operation. The braking force required to bring the vehicle to a standstill is generally less than the braking force applied during braking. Therefore, in a rear-end collision, the stationary vehicle can be moved despite the brakes being applied. If a vehicle collides with the stationary vehicle from behind, the vehicle is accelerated sharply, and due to inertia, the heads of the vehicle occupants are initially thrown backward and then forward relative to the vehicle, while the torso is restrained by the seatbelt. Both the forward and backward movements of the head can lead to injuries in the cervical spine. This risk is significantly reduced by the method according to the invention.

[0014] In Fig. Figure 1 shows an exemplary embodiment as a flowchart. This flowchart represents a program implemented in the control unit's microcomputer. This program is started, for example, when the ignition is switched on, and is executed cyclically until the ignition is switched off.

[0015] In step 1, the vehicle's speed is determined using the vehicle's sensors, for example, an electronic stability program or an anti-lock braking system. In step 2, a decision is made as to whether the vehicle's speed falls below the predefined limit, in this example, 10 km / h. If the vehicle is traveling at a higher speed, the program will return to the point before step 1. If the speed falls below the predefined limit, signals from the restraint system or the environmental sensors, ideally from the ultrasonic sensors S, are used. UThe parking aid 21 is read in step 3. In step 4, these signals are used to check whether another vehicle is approaching from behind. If no vehicle is approaching, the program returns to the point before step 1. If an approaching vehicle is detected, at least its distance and approach speed, determined from cyclically repeated distance measurements, are recorded in step 5. Then, in step 6, a control unit 23 determines whether there is a risk of collision with the vehicle behind. In the simplest case, this can be done by comparing the assumed braking distance of the vehicle behind at the measured approach speed with the measured distance, or by calculating the time until the collision. Possible evasive maneuvers by the vehicle behind can also be taken into account.If these calculations indicate that no collision with the approaching vehicle is imminent, the program will return to step 1. However, if such a collision is imminent, the vehicle speed will be checked again in step 7. If step 8 reveals that the vehicle is moving, the program will return to step 1. If the vehicle is stationary or nearly stationary, any accelerator pedal input will be recorded in step 9, and in step 10, a decision will be made as to whether the driver intends to start driving. If the driver intends to start driving, the program will return to step 1. If the driver intends to start driving, the braking system will automatically perform full braking in step 11, applying maximum braking force to the wheels. The program will then return to step 9.

[0016] To implement the braking, an electro-hydraulic braking system, an electro-pneumatic or an electromechanical braking system is used.

[0017] Communication between the various systems involved can take place via a bus system, for example the vehicle's CAN bus.

[0018] In another embodiment, the automatic braking can be terminated when the vehicle comes to a standstill after the collision, which is determined, for example, by means of wheel speed, acceleration and / or yaw rate sensors.

[0019] In Fig.Figure 2 shows an exemplary system architecture. The control unit 20 of the electronic stability program receives signals from various sensors 25, 26 regarding wheel speed, accelerator pedal position, etc., and transmits the information about the vehicle speed and accelerator pedal position to the control unit 23. Furthermore, the parking aid unit 21 receives signals from the surrounding sensors S U and transmits the information about a vehicle approaching from behind, in particular its distance, its approach speed and / or the time until the collision, to the control unit 23. Then, in the event of an intervention, the control unit 23 sends signals to activate the braking to the brake actuator 24, e.g. the ESP hydraulics.

Claims

[1] Method for controlling a vehicle's braking system to reduce the consequences of a collision with another vehicle, characterized by , that (a) the speed of the vehicle is monitored, and (b) signals from environmental sensors are evaluated and (c) if the vehicle is stationary and if the evaluated signals indicate a risk of collision with a vehicle approaching from behind, the braking system is automatically triggered, wherein the evaluation of the signals from the environmental sensors consists of a comparison of the measured distance of the vehicle approaching from behind with the assumed braking distance of the rear vehicle at the determined approach speed, wherein the signal for triggering the braking system is generated when the measured distance approaches or falls below the assumed braking distance of the approaching vehicle at the measured approach speed, wherein the braking system comprises all actively controllable braking means available in the vehicle, and if it is automatically triggered in step (c), the maximum possible braking force is generated. [2] Method according to the preceding claim, characterized by, that the procedure is started when the ignition is switched on and is repeated cyclically until the ignition is switched off. [3] Method according to any one of the preceding claims, characterized by , that the signals in step (b) are obtained using ultrasonic sensors of the parking aid device. [4] Method according to any one of the preceding claims, characterized by , that the brake force build-up in step (c) only takes place if the driver does not indicate a driving request by pressing the accelerator pedal. [5] Method according to any one of the preceding claims, characterized by that the vehicle's speed is determined by means of sensors of the electronic stability program or an anti-lock braking system. [6] Method according to any one of the preceding claims, characterized by that the automatic braking will end when the driver indicates a desire to accelerate by pressing the accelerator pedal.

Images