Method for controling or regulating the deceleration or braking of a vehicle

0001The invention relates to a method for controlling or regulating the delay or Braking of a motor vehicle as a function of the braking distance currently present during driving or from the current distance to the vehicle in front, in which the delay or Braking of the vehicle is effected by the vehicle brake is actuated when exceeding predetermined driving-related parameter limits, and in the case of falling below said parameter limits a delay caused only by the engine drag torque is generated, according to the preamble of claim 1.

0002Operating methods of this type are already widely known. In their function, they refer to either assisting the braking process in the event of an emergency braking or, in the case of a far enough braking distance to the vehicle in front, only using the braking via the engine braking torque.

0003Braking methods of this type include so-called ADR systems, with a distance control for determining the distance to the vehicle in front and a corresponding influence on the acceleration or Delay of the vehicle are equipped. The braking or deceleration strategies are generally subdivided into two essential driving situations. Up to a certain deceleration, which is correlated with the existing braking distance, only a delay on the engine drag torque is effected. This is the commonly used engine brake. In this case, no intervention takes place via the brake system of the motor vehicle, but the fuel supply is either reduced or switched off completely in so-called Schubabschaltsystemen during the delay. The internal friction resistances of the engine in operation cause this delay. The second essential driving situation takes into account the target deceleration and occurs at a corresponding value with respect to the existing braking distance. The existing braking distance is determined from the distance to the vehicle in front. In other words, this means that the brake system is applied as soon as the deceleration on the engine drag torque alone is no longer possible within the existing remaining braking distance. The second-mentioned driving situation could in turn be divided into driving situations that are uncritical, and in which only the engine drag torque nor an additional delay component on the brake system is needed, and those that are critical, namely the emergency braking, in which it depends, the remaining braking distance optimal to use and if necessary. To bypass the normal reaction times of the driver or the system by accelerating the braking process.

0004For this purpose, technical embodiments are known in the prior art. So is in the DE 4430461 A 1 shows a method for controlling the brake pressure as a function of the pedal actuation speed. From this step, possible solutions are known, as so-called emergency braking actions can be detected. As evaluation parameters, the pedal actuation speed is used in this cited prior art. It is assumed that the driver usually operates the brake pedal relatively hectically when emergency braking is initiated. If this is detected, braking acceleration means are used, which lead to an increase in the brake pressure in the brake system. The brake pressure increase is only made dependent on the pedal actuation speed and no longer on the pressure signal generated by the driver on the brake pedal. That is, when the driver operates the pedal quickly, the control pressure is not proportional but disproportionately fed into the brake fluid circuit.

0005In this mentioned prior art, the measures described apply excluding the exact evaluation of this there called Zuschaltschwelle, so that pedal actuation speed, from which the disproportionate brake pressure generation is controlled. In this case, adaptive measures are also already included in the method, which, however, relate only to the evaluation of said switching threshold.

0006Thus, the objective presented there is that it is assumed that there are cases in which, during emergency braking, the driver operates the pedal at a high speed, but only exerts an insufficient force on the pedal. In this situation, the external force therefore assists the driver and causes a braking force that is higher than the braking force that would correspond to the pedal force during normal pedaling.

0007A disadvantage of this method, however, that the strategic control of braking is more or less exclusively focused on the evaluation of the pedal travel or the pedal actuation speed. However, this is insufficient for the evaluation of driving situations.

0008From EP 0661188 A1 an automatic vehicle speed control system is known in which also a distance controller is used. In addition to the distance signal, this system definitely works with the vehicle speed. Thus, in this case essentially relative variables are detected and utilized according to the control technology. The system shown in this prior art is thus a tachometer system in the usual sense, which correlates with a distance control. Specific measures that evaluate the braking events as such are not shown because the system essentially deals with a strategic adjustment of the speed. D. h., Braking operations are used in this prior art only as adjusting operations for the strategic or tactical assessment of an average speed or an optimal usable speed. An optimization of the brake as such does not take place here.

0009The present invention is therefore based on the object to be able to carry out the deceleration or braking of the vehicle in normal driving situations economically and in dangerous driving situations with optimal utilization of the remaining braking distance.

0010The object is achieved according to the invention in terms of a method of the generic type by the characterizing features of claim 1. Further advantageous embodiments of the method according to the invention are specified in the dependent claims 2 to 11.

0011For a better understanding, briefly two technical terms are explained, which play a special role in the method according to the invention.

0012It is important to distinguish between tactical policies and strategic procedures. The following is meant. In a tactical procedure, only the current situation change is always technically reacted. That is, the system works exclusively with sharp limits, the excess of only one operation or generate a manipulated variable. In strategic procedures, however, situations are observed over a period of time and the driving situation as such is then optimized within limits. Of course, such a strategic approach requires adaptive systems that work on patterns. Adaptive means that the system detects a multitude of driving situations with the aid of microprocessors and corresponding storage media and always optimizes their parameters during the control.

0013The essence of the invention is therefore to take into account for optimal control of the deceleration or braking of the vehicle, a plurality of parameters that reflect the current driving situation. The core of the invention is thereby, with the aid of a plurality of evaluated parameters, the braking system or the distance-regulating deceleration system <img file="EP0899174A2_D0001.tif" />driver-adaptive ".

0014The invention according to the invention is used essentially in two operating modes,<ul id="ul0001" list-style="none"><li><b>a)</b> Manual braking Integration of the driver and situation-specific parameters according to the invention during braking which are initiated by brake pedal operation. This supports the braking initiated by the driver.</li><li><b>b)</b> Automatic braking or deceleration with ADR Integration of the driver situation-specific parameters according to the invention into an activated distance control system ADR. This is automatically braked, in the way that the braking behavior of the driver is modeled in accordance with the invention.</li></ul>

0015The basic procedure according to the invention when learning or adapting the driver-specific braking or deceleration parameters is the same for both operating modes. The two modes mentioned bind this determined driver-specific braking strategy data either during manual braking or during automatic braking or deceleration during ADR operation.

0016Based on the two parameters target deceleration and existing braking distance - identically with distance to the vehicle ahead - the so-called map is extended by a further parameter, namely the actual speed. The resulting map has a three-dimensional character. In a further embodiment of the method, however, it also makes sense to determine the coefficient of friction of the roadway as a further parameter and to include it in the regulation of the braking. In this case, the resulting map is a four-dimensional one. However, the essence of the invention consists not only in the inclusion of a plurality of parameters in the regulation of the braking or deceleration of the vehicle, but in the whole system as already stated <img file="EP0899174A2_D0002.tif" />This means that the individual braking behavior, or even the overall driving behavior, of each individual driver as <img file="EP0899174A2_D0003.tif" />It is also taken into account, for example, that in most cases a vehicle is not only used by a driver, but the method according to the invention always starts from a basic characteristic map which is either a permanently stored one or the last one optimized.

0017The map, which will be described below, can either be present as a numeric map, or in the form of so-called fuzzy rules, or as a neural network. The procedure is that the following data is collected via an algorithm while driving with uncontrolled distance control ADR: Speed, target deceleration, friction coefficient of the road and distance at which the braking intervention by the driver takes place.

0018Already here it is clear that in the method according to the invention, the adaptive Syste m is able to determine the driving and braking habits of the driver already at the first braking action . That is, the system detects whether the driver, for example, rather defensive drives and a slightly higher distance to the vehicle ahead or whether his driving style is more aggressive and thus is much closer to the physical borderline situations. These parameters determined from the current braking values ​​are stored as additional characteristics. Due to the correlation between speed and distance, it is also possible to detect dangerous driving situations before the occurrence of a current braking request. The said adaptation of the so-called map is carried out by superposition or numerical addition of the existing map with the said additional map. Again, the additional map can be either numerically, that is, by analytical formulas, or by fuzzy rules, or as a neural network.

0019The procedure according to the invention can be described using the example of the abovementioned four-dimensional characteristic field such that there exist four sensor complexes which are present, a distance sensor for determining the distance to the vehicle in front or to an obstacle; a so-called pressure-medium-operated brake unit for determining the target deceleration; Determination of the actual speed; a coefficient of friction of the roadway or the coefficient of friction between the wheel and the road. These four parameters then enter into said so-called additional map. This map <img file="EP0899174A2_D0004.tif" />learns "whenever new parameters are provided, either in appropriate time cycles or triggered by a significant change in the current driving situation. These are read into the additional map. We already stated above, the system always has its own map, which is for example fixed or comes from the last determined optimized map from the last phase of operation of the vehicle. This existing map can be provided with every new commissioning of the vehicle. Now, from the currently learned additional map with the current driving situation data, an overlay with the existing map takes place. The result of the overlay is the said adapted map. As a result, this means that the inventive method is capable of so-called different <img file="EP0899174A2_D0005.tif" />Furthermore, according to the invention, it is then not only possible to recognize these but also to optimize the delays or braking of the vehicle for each driver type.

0020As a result of the use of a plurality of parameters, the driving situations as such are considerably more differentiable, which in the present invention, as already explained, goes so far that even different driver types can be recognized. This ultimately leads to the fact that it can be recognized whether the respective driver in the sense described above, a more tactical, or a more strategic defensive driving behavior. Accordingly adapted exactly with the procedure according to the invention a correspondingly more tactical or more strategic regulation of the braking operation possible. In addition, the system according to the invention is so universal that otherwise known and customary brake systems can be included in the procedure according to the invention.

0021The invention is illustrated in terms of their procedure in the drawing and described in more detail below.

0022It shows:<dl id="dl0001"><dt>Fig. 1:</dt><dd>Function diagram for procedural procedure.</dd><dt>Fig. 2:</dt><dd>2-dimensional characteristic map.</dd></dl>

0023FIG. 1 makes the procedure of the invention clear. The values ​​of a distance sensor 1, a pressure-medium-operated brake unit 2 for determining the desired deceleration, a tachometer system 3 for determining the actual speed, and a coefficient of friction recognition 4 for determining the current coefficient of friction of the roadway are provided as input variables for determining said parameter field. Thus, 4 parameters are available as evaluation variables in this example. As further explained below, further evaluation variables can be taken into account by additional sensors or calculations. These evaluation quantities are fed to a detection system 10, in which the additional map is formed. The said characteristic field is a correspondingly four-dimensional data field. This data field is able, either in adjustable time clocks or quasi-continuously continuous sensor values ​​or To detect parameters of the individual sensors 1 to 4. In addition, however, the unit 10 may include a microprocessor system through which the parameters and their corresponding assignment are calculated by analytical formulas. As already stated, the said values ​​of the sensors 1 to 4 are determined while the vehicle is not being switched on (ADR). For example, it can be determined at which current parameters the speed, setpoint deceleration, coefficient of friction and distance of the driver reacts with a braking intervention.

0024Taking into account the two above-mentioned operating modes in which the method according to the invention can be incorporated, the following parameters are expediently to be taken into account below:<ul id="ul0002" list-style="none" compact="compact"><li>For a) manual braking intervention: The expediently considered parameters are distance or Braking distance, gradient detection, actual speed and actual acceleration, steering angle, brake pressure, coefficient of friction and accordingly actual deceleration or Istbremsdruck. In this mode of operation, the system simply compares the actual and desired brake pressures and, accordingly, increases the brake pressure when the driving situation requires it. In the process according to the invention, this also takes place as a function of the named driver-specific parameters.</li><li>For b) automatic braking or deceleration. The expediently considered parameters are distance or braking distance, gradient detection, actual speed and actual acceleration, steering angle, brake pressure, coefficient of friction. In this operating mode, the system then delivers the setpoint deceleration or setpoint braking pressure to the brake system 50 at the output of the adapted characteristic map 40 which will be described below.</li></ul>

0025The additional map of the unit 10 contains the values ​​which describe the driver's braking strategy mathematically or physically.

0026Moreover, the system has an already existing reference map 20, which consists for example of a fixed-applied optimized map, or consists of a longer than optimal operating phases determined map. Then there is an overlay in a unit 30, which for example by adding the existing map with the additional map interferes or superimposed. The result is an adapted map 40, which now contains the individual driver-typical braking strategy in the form of one or more parameter sets. In order to be able to make a driver-typical distinction and to come to an adapted map, it is necessary, as already said, to start from an existing fixed map 20 as a reference. Only in this way can driver-typical deviations be recognized.

0027Based on the adapted map 40 then the engagement is formed on the brake system 50. The brake system 50 comprises on the one hand the entire pressure-medium-operated brake unit as well as the hierarchically superior electronic control components of the brake. This may include ABS - Anti-lock Braking System - as well as other systems.

0028In principle, the adaptation strategy can be carried out according to various specifications:<ul id="ul0003" list-style="none"><li>1. The system adapts itself again and again when the vehicle is put into operation and deletes the additional map when the vehicle is taken out of service.</li><li>Second The system always adapts without deleting the additional map 10.</li><li>Third The system stores a number of additional maps and uses the correct map after driver identification. The driver identification can be made by each driver using a personally coded ignition key or a query on the display of the vehicle.</li><li>4th The system stores a number of additional maps 10 and uses the correct map in which it compares the driver's braking actions with the existing auxiliary maps and then selects the most appropriate map.</li></ul>

0029The detection or determination of the braking strategy of the respective driver is called functional that, for example, is determined at what speeds and at which distance, at which coefficients of friction of the road, etc., the respective driver initiates braking with which set deceleration.

0030FIG. 2 shows in a diagram the function or the mathematical structure of a map, but only with two-dimensional character. Plotted on the ordinate is the desired deceleration SV and plotted on the abscissa is the existing braking distance vBw, which is determined from the distance to the vehicle in front. In this functional dependence of the two parameters to each other appears a straight line, the delays to be introduced or Braking divided into two areas. Above the curve, ie, for SV values ​​as a function of vBw values ​​above the straight line, it is sufficient to use the engine drag torque to decelerate the vehicle. Below the straight line shown, it is already necessary to use the brake system.

0031This only two-dimensional map makes clear on the one hand, in which dependence of the parameters considered which type of braking is necessary and on the other hand, this diagram makes it clear that there are functional dependencies between the parameters. The functional dependence in this two-dimensional map is represented by the straight line. In contrast, the invention invention now extends the map to a higher-dimensional character, which, as already stated above, three or four-dimensional, or may be 7-dimensional or higher in inclusion of all mentioned parameters. This makes the influence on the braking more effective and differentiated.

0032The method of the present invention can be combined into conventional systems with ABS anti-lock braking system, with slip control systems, and / or with ADR steering control systems.

0033Overall, the use of the method according to the invention not only leads to an increase in safety but also to an increase in ride comfort.