WO2004098942A1 - Method and device for gently stopping a vehicle - Google Patents

Abstract

The invention relates to a method for gently stopping a vehicle (1) equipped with an all-around sensor system (6), according to which, during a braking, the pitching of the vehicle (1) caused by the braking, is minimized by a braking intervention. When initiating a braking, signals of the all-around sensor system (6) are analyzed with regard to an impending risk of collision. A braking intervention that minimizes the pitching of the vehicle (1) is ceased when a risk of collision is established based on the signals furnished by the all-around sensor system (6).

Description

Method and device for stopping a vehicle smoothly

State of the art

The invention relates to a method and a device for stopping a vehicle smoothly according to the preamble of independent claims 1 and 7.

In vehicles equipped with an electrohydraulic brake, a jerk-free stopping is made possible in that the corresponding pitching of the body of the vehicle associated with the braking process is minimized shortly before the vehicle comes to a standstill by a corresponding control of the brake by means of a control device. The driver perceives this braking intervention as essentially jerky braking to a standstill. The smooth braking, however, extends the braking distance. It is therefore also known to operate the control device in such a way that when braking is initiated quickly or one Full braking the jerk-free stopping function is not activated in order to keep the braking distance as short as possible.

From DE 197 03 688 AI, a method and a device for controlling a brake system are known in which, depending on a driver's braking request, the braking force is adjusted in at least one wheel. In an operating state in which a transition to a standstill of the vehicle is to be expected, the braking force on this at least one wheel is reduced independently of the driver's braking request.

Advantages of the invention

The invention aims at an advantageous further development of the known system, on the one hand to benefit from the increased comfort of such a brake system with the function jerk-free stopping, but on the other hand to satisfy an increased safety aspect. The invention is based on the knowledge that, in particularly critical risk situations, even a small gain in braking distance can be more useful for safety than increased comfort. The invention therefore enables early detection of situations in which it makes more sense to forego the comfort function without jerking in order to gain braking distance.

drawing

The invention is explained in more detail below with reference to the drawing. 1 shows a block diagram of a device, FIG. 2 shows a flow chart in a known method, FIG. 3 shows a flow chart in a method according to the invention. description

Figure 1 shows a block diagram of a device. A vehicle 1 is equipped with an all-round sensor system 6, which preferably comprises video systems, radar systems, lidar systems and ultrasound systems or at least some of these systems. The surroundings of the vehicle 1 are monitored with this all-round sensor system 6. In particular, this all-round sensor system 6 can also determine the distance of the vehicle 1 from other vehicles very precisely. Reference number 2 denotes a navigation system, reference number 2a denotes the antenna system for this navigation system. Reference number 3 denotes a first control device for the brake system of vehicle 1. Reference number 5 denotes a further control device, the function of which can alternatively also be integrated into the first control device 3. The control device 5 regulates a comfort function which reduces a nodding of the vehicle 1 during a braking operation and in this way enables the vehicle 1 to be stopped smoothly. The control device 5, or the control function represented by this control device, can be deactivated by switching means 4. The switching means 4 can be controlled by the control device 3 as a function of signals from the all-round sensor system 6

FIG. 2 first shows a sequence program in a known method. In this method, the driver of the vehicle initiates a braking operation in step 20. In step 21 it is checked whether full braking takes place. For this purpose, a threshold value for the brake pressure is specified. If the brake pressure exceeds this threshold value, it is assumed that full braking takes place. Depending on this decision, the further procedure is then decided and a branch is made to one of the following alternatives. If the predefinable threshold value of the brake pressure is exceeded, a branch is made to the alternative step 21B. This step means that step 23 is not initiated. In step 23, the controller for the jerk-free braking to a standstill was activated in order to achieve greater driving comfort. If it is determined in step 21 that the threshold value for the brake pressure has not been exceeded, the method branches to alternative step 21A. This step leads to step 23, in which the controller for the jerk-free braking is activated to a standstill, thus enabling very comfortable braking. In addition, after a braking operation has been initiated by the driver of the vehicle, the speed of the brake actuation is checked in a step 22. This is achieved, for example, by specifying a further threshold value for the change in the brake pressure over time and comparing the rate of change of the brake pressure with this threshold value. If this threshold value is exceeded, a branch is made to alternative step 21A, which does not lead to activation of the controller for jerk-free braking (compare step 23). However, if the aforementioned threshold value is not reached, the alternative step 21B is followed, which is then followed by step 23. In step 23, the controller for smooth braking is activated. In the conventional method, the comfort function of jerk-free braking to a standstill in the sense of risk weighing is then deactivated if an emergency situation is inferred due to panic braking or full braking.

The invention now aims to further improve and refine this known method by introducing further decision criteria which are based on information from an all-round sensor system. This new method is now explained using the flow chart shown in FIG. 3. During the entire braking process, an all-round sensor system 6 (FIG. 1), which in particular comprises video systems, radar systems, lidar systems and ultrasound systems, monitors the surroundings of vehicle 1 and a current probability of collision is determined by modeling both the vehicle's own dynamics and the dynamics of the objects that may be detected. If the driver then initiates braking (step 30), for example, first, analogously to the known example explained with reference to FIG. 2, it is checked whether full braking is taking place (step 31). As already described above, this test can preferably be carried out by comparison with a predefinable threshold value for the brake pressure. If it is determined that the braking is full because the predefinable threshold value for the brake pressure has been exceeded, the method branches to alternative step 31B, which leads to step 35, in which the comfort function for jerk-free braking is deactivated. In the block diagram shown in FIG. 1, this is indicated by a switching means 4 which interrupts a connection between a control device 3 responsible for controlling the braking process and a control device 5 responsible for implementing the aforementioned comfort function. This is only meant as an example. Of course, all functions can also be carried out by a single control unit. The switching means that deactivate the comfort function without jerking is then also integrated in this single control device. If braking is not recognized after initiating a braking operation, because of the

Brake pressure does not exceed a predeterminable threshold value, then an alternative is branched to step 31A, which leads to step 33. In step 33, the information from the all-round sensors 6 is evaluated. In particular, it is determined whether, taking into account the braking process initiated and the traffic situation determined by the all-round sensor system 6, there is a risk of a collision or not. If the result of this check shows that there is no risk of collision, the system branches to alternative step 33B, which leads to step 35. In step 35, the controller for the comfort function, jerk-free braking to a standstill, is activated. This comfort function is then active and the vehicle can be braked to a standstill in accordance with this comfort function. If, on the other hand, it is determined in this check in step 33 that there is a risk of collision, a branch is made to alternative step 33A, which in turn arrives in step 31B. With this variant, the comfort function is deactivated as described above, with the result that a longer braking distance is available.

In an advantageous development of the solution according to the invention, if such a risk situation is ascertained, the all-round sensor system 6 can expediently also influence the control device 3 in such a way that the braking process initiated is intensified further, for example in the sense of full braking. This reduces the risk of an impending collision.

Furthermore, according to step 32, it can also be checked whether panic braking is present. As already mentioned above, this can expediently be brought about by specifying a threshold value for the temporal change in the brake pressure and comparing this threshold value with a current measured value of the rate of change of the brake pressure. If it turns out that the predeterminable threshold value of the brake pressure is exceeded during the initiated braking process, a branch is made to the alternative route 32B, which leads to the comfort function jerk-free braking being deactivated. Step 35, in which this comfort function is implemented, is therefore not activated. However, if it turns out during the test provided in step 32 that the predefinable threshold value is not exceeded, the system branches to alternative step 32A. This step 32A then leads to step 34, in which an additional check is carried out with the aid of the information provided by the all-round sensor system 6. As already described above, a check is made as to whether or not there is a risk of collision, taking into account the braking process initiated and the information from the all-round sensor system. If a collision risk cannot be ruled out as a result of this check, the system branches to alternative step 34A, which leads to step 32B. In this step it is determined that the comfort function smooth braking is deactivated. If, on the other hand, it is determined during the check in step 34 that there is no risk of collision, the system branches to alternative step 34B, which ultimately leads to step 35, in which the comfort function is active.

In the variant just described, in an advantageous development of the invention, the information obtained from the all-round sensor system can be used to influence the braking process. If the result in the check in step 34 is that the comfort function must be activated without jerking due to the risk of a collision, a corresponding signal can additionally be sent to the control unit 3. The control device 3 can then influence the braking process in the sense of faster braking.

The solutions according to the invention enable further optimization and an even more reliable determination of priorities when it comes to the question of whether a comfort function can be switched off at least temporarily in order to gain safety. In addition, there are additional signals for intensification in a dangerous situation of a braking process that may have been initiated too slowly.

Claims

claims 1. A method for jerk-free braking of a vehicle (1) equipped with an all-round sensor system (6), in which during a braking operation the pitching of the vehicle (1) caused by the braking operation is minimized by a brake intervention (control unit 3, 6), characterized in that that when the braking process is initiated, signals from the all-round sensor system (6) point to an impending Risk of collision are checked and that the braking intervention that minimizes the pitching of the vehicle is omitted if a collision risk is concluded on the basis of the signals supplied by the all-round sensor system (6). 2. The method according to claim 1, characterized by the following steps: 2.1 A threshold value for the brake pressure is specified, 2.2 After initiating a braking process, the current braking pressure is compared with the predefinable threshold value. 2.3 If the threshold value is not exceeded, the signal from an all-round sensor system (6) is transmitted to the If there is a risk of collision, 2.4 If a risk of collision is determined, the braking intervention that minimizes the nodding of the vehicle (1) is avoided. 3. The method according to any one of the preceding claims, characterized in that an initiated braking process is amplified in the sense of full braking. 4. The method according to any one of the preceding claims, characterized by the following steps: 4.1 A threshold value for the change in the brake pressure over time is specified, 4.2 After initiating a braking process, the current value of the time change of the Brake pressure compared with the predefinable threshold value, 4.3 If the threshold value is not exceeded, the signal from an all-round sensor system (6) is checked for the risk of a collision, 4.4 If a risk of collision is determined, the braking intervention that minimizes the nodding of the vehicle (1) is avoided. 5. The method according to claim 4, characterized in that an initiated braking process is accelerated in the sense of full braking. 6. The method according to any one of the preceding claims, characterized in that the tests for exceeding the predefinable threshold values for the brake pressure and the temporal change in the brake pressure are carried out essentially in parallel. 7. Device for stopping smoothly with one All-round sensor system (6) equipped vehicle (1) with a control device (control units 3, 5) for suppressing the pitching of the vehicle (1) occurring during a braking operation, characterized in that means (switching means 4) for influencing the Control device as a function of signals from the all-round sensor system (6) are provided.