Collision avoidance procedures and means for their implementation

Abstract

A collision avoidance method (400) is proposed which comprises braking (420) a vehicle (1) during a braking period when a collision-relevant object (2) is detected in a collision monitoring area (3), and which comprises conditionally enabling (430) a restart of the vehicle (1) during a release period after the braking period, wherein the enabling (430) of the re-acceleration of the vehicle (1) is carried out under the condition that the collision-relevant object (2) is determined to be a less critical collision-relevant object (2), and wherein a limitation of the re-acceleration is carried out at the beginning of the release period if the collision-relevant object (2) is still detected in the collision monitoring area (3).

Description

The present invention relates to a collision avoidance method and means for implementing such a method.BackgroundVehicles may be configured to avoid collision to perform collision avoidance methods, which may be based on, for example, camera, ultrasound, radar, or lidar technology.Collision avoidance methods are known in particular from the field of passenger cars. However, they can also be used with mobile work machines, optionally with corresponding adaptations. Embodiments proposed here can relate to both fields of application.OverviewA collision avoidance method and means for implementing the same are proposed, having the features of the independent claims. Advantageous embodiments are the subject matter of the dependent patent claims and of the following description.The proposed collision avoidance method comprises braking a vehicle during a deceleration period when a collision relevant object is detected in a collision monitoring region, and conditionally enabling re-acceleration of the vehicle during a release period after the deceleration period. The release of the reacceleration is carried out under the condition that the collision-relevant object is determined as a less critical collision-relevant object, and a limitation of the reacceleration at the beginning of the release period is carried out at least when the collision-relevant object continues to be detected in the collision monitoring region.As explained in more detail below, the proposed method prevents a strong re-acceleration from occurring after the end of an intervention for collision avoidance and, as a result of this, a corresponding intervention for collision avoidance, which can be perceived as unpleasant by a driver of a corresponding vehicle and cannot be immediately understood by the driver. If the collision-relevant object is no longer detected in the collision monitoring area, for example because it has moved out, in embodiments the full acceleration can be released again, which increases the availability of a corresponding vehicle.In one configuration of the proposed method, the limitation of the reacceleration at the beginning of the release period can be carried out using a reacceleration limiting value which is raised during the release period. In this way, it can be ensured that at later times, at which the explained undesired renewed interventions for collision avoidance are no longer to be expected, again increasing accelerations are available, up to a maximum acceleration.In one configuration of the proposed method, a time to collision (TTC) with the collision-relevant object may be predicted, and a collision-relevant object may be recognized as a less-critical collision-relevant object if the predicted time to collision is above a predefined threshold value. In this way, it can be ensured that the method is limited to those collision-relevant objects for which a collision is not to be expected directly or within a short period of time.In one configuration of the proposed method, the release of the reacceleration can be carried out as release of an acceleration operating unit operated by a driver of the vehicle or of an acceleration request signal thereof. In embodiments, the acceleration control unit can be an accelerator pedal or so-called accelerator pedal. Corresponding embodiments can advantageously be integrated into existing systems which already provide an accelerator pedal limitation or a corresponding limitation of an acceleration request signal in another context.In one configuration of the proposed method, the limitation of the reacceleration at the beginning of the release period can be carried out on the basis of a speed of the vehicle. In this way, it can be ensured, in particular, that the measures introduced are adapted to the respective speed of the vehicle.In one configuration of the proposed method, this can be carried out in a mobile work machine as the vehicle. As explained below, mobile working machines such as wheel loaders, excavators, stackers and the like are in particular at risk of collision because of the possibly invisible travel path, so that these can benefit particularly from the proposed measures.The proposed collision avoidance system, which can be implemented in a vehicle, for example a mobile work machine, and which can comprise this or these as part of the system, has a control unit which is configured to brake a vehicle during a braking period when a collision-relevant object is detected in a collision monitoring region, and which is configured to conditionally enable re-acceleration of the vehicle during a releasing period after the braking period. The control unit is configured to enable the reacceleration of the vehicle on the condition that the collision-relevant object, which is initially to be regarded as critical without or with corresponding checking, is determined at the end of the intervention for collision avoidance as a less critical collision-relevant object, and the control unit is configured to limit the reacceleration at the beginning of the enabling period at least if the collision-relevant object is still detected in the collision monitoring region.With regard to further features and advantages of a corresponding collision avoidance system and different configurations thereof, express reference is made to the above explanations relating to the proposed collision avoidance method and its configurations, since these apply in the same way for this purpose.The proposed computing unit comprises a processor which is configured to execute the proposed method, in particular according to any of the configurations explained above and below. This too benefits from the explained advantages of the proposed method and its embodiments.The same applies correspondingly also to the proposed computer program which comprises instructions which, when the computer program is executed by a computer, cause the computer to execute a collision avoidance method, as has been explained above in different embodiments.The computer-readable data carrier proposed, on which a corresponding computer program is stored, is essentially the same.The implementation of the proposed method or its embodiments in the form of a computer program or computer program product with program code for carrying out all method steps is particularly advantageous since this causes particularly low costs, in particular if an executing control device is also used for further tasks and is therefore present in any case.Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, such as hard disks, flash memories, EEPROMs, DVDs, among others. Download of a program via suitable computer networks (Internet, intranet, cloud, etc.) is also possible.DESCRIPTION OF THE FIGURESFIG. 1 shows a simplified representation of a collision avoidance system. FIG. 2 illustrates speed patterns in collision avoidance systems. FIG. 3 shows aspects of a collision avoidance system in simplified representation. FIG. 4 shows a simplified illustration of a collision avoidance method.EmbodimentsThe embodiments described below are described merely for the purpose of assisting the reader in understanding the claimed and previously explained features. They merely represent representative examples and should not be considered exhaustive and / or restrictive with regard to the features of proposed configurations.It is to be understood that the advantages, embodiments, examples, functions, features, structures, and / or other aspects described above and below are not to be viewed as limitations on the scope of the invention as defined in the claims, or as limitations on equivalents to the claims, and that other embodiments may be utilized and changes may be made without departing from the scope of the claimed invention.Various embodiments may include, include, consist of, or consist essentially of other suitable combinations of the described elements, components, features, parts, steps, means, etc., although such combinations are not specifically described herein. Moreover, the disclosure may include other inventions that are not presently claimed, but which may be claimed in the future, particularly when included within the scope of the independent claims.Explanations relating to apparatuses, apparatuses, arrangements, systems, etc. according to embodiments proposed herein may also apply to methods, processes, methods, etc. according to the embodiments proposed herein, and vice versa. Identical, identically acting elements of identical construction, structurally identical or comparable construction corresponding to one another in terms of their function, and method steps etc. can be indicated in the drawings with identical reference numerals.Reference is first made to FIG. 1, which shows a vehicle 1, here a mobile working machine designed in the form of a wheel loader.Collisions of mobile work machines in particular represent a considerable risk for humans and machines. Particularly in the case of limited visibility (caused, for example, by a loaded bucket on a wheel loader or a loaded trough on a dumper), severe accidents can occur. Systems for avoiding or mitigation of such collisions are known and these may include, for example, backup cameras and bird eye view cameras for better surround vision, but also systems for collision warning and avoidance based on camera, ultrasound, radar or lidar technology. As assistance systems, these can increase the safety of the machine operation. In systems based on surroundings sensor systems (e.g. radar), an obstacle (e.g. person, vehicle or wall) is detected by the sensor system.For this purpose, the vehicle 1 has a detection arrangement 11 which is illustrated here by dashed lines and is in no way restricted with regard to its structural configuration and can have, for example, sensors distributed on the vehicle 1 and one or more decentralized, distributed or central evaluation units. The detection arrangement 11 can have, in particular, video, radar, lidar, ultrasonic or infrared sensors of any type, combination and interconnection and / or be configured for communication with other vehicles in order to detect objects 2. The detection arrangement 11 detects a detection region 12, which is likewise illustrated here in dashed lines and can comprise a travel path of the vehicle 1 or can represent the latter.A corresponding detection arrangement 11 can be configured in particular to perform the assignment of the object 2 to object classes. In this way, the object 2 can be recognized, for example, as a non-activated object 2, or as an activated object 2, for example, as a human. Embodiments of the present invention may or may not include a corresponding classification. The discussion above and below refers to a "collision-relevant" object 2, which can differ from another object, i.e. in particular from a non-collision-relevant object, specifically for example already in that it is located in the detection region 12.A collision-relevant object 2 can differ from another object in that a collision with this results in undesirable effects, for example damage to the vehicle 1 or the object 2. A non-collision-relevant object can be characterized, for example, in that it is too small or is located flat on the ground, such as a gully cover of a rain gutter or sand located on the road. The criterion for a non-collision-relevant object is that it does not lead to any negative effects in the event of a collision. An object 2 can be identified, for example, by a user definition or specification in the detection arrangement 11 as a collision-relevant object 2, i.e. classified accordingly, for example.Collision-relevant objects 2 can be detected as a function of the detection by different sensor systems. Depending on whether an object 2 can be detected by means of a radar, lidar or video sensor or by a combination thereof, the objects 2 can be assigned to the object classes.Known systems for collision avoidance, which can be implemented, for example, using a control unit 15 of the vehicle 1, can determine a time to collision (TTC) on the basis of the transmitted distance to the object 2 and its relative speed. Such systems are already known from the automotive sector and are also used with corresponding adaptations in the field of mobile work machines.The TTC, also referred to herein as "time to collision (expected)", denotes the estimated time remaining until a collision occurs when two objects, such as any type of vehicles, maintain their current heading and speed. This calculation is a key part of many modern safety systems aimed at avoiding collisions. Of course, a time until a collision occurs between a moving vehicle and an unmoved object can also be determined accordingly.The TTC is usually calculated by dividing the distance between the two objects under consideration (or a vehicle and another object) by the relative speed. This presupposes that both objects move in a straight line and at constant speed. In the case of other movement trajectories and / or varying speeds, correspondingly adapted calculation methods can be used, which are known per se, however.TTC systems are used in various fields of technology, including automotive (e.g., driver assistance) systems, aeronautics (i.e., collision avoidance systems for aircraft), and robotics (e.g., autonomous vehicles). Different warnings and / or actions may be initiated based on the TTC. If the calculated TTC falls below a certain threshold value, which indicates an imminent collision, warning systems can alert the driver or operator, so that the latter can initiate a collision-avoiding intervention, or initiate automatic actions, such as, for example, the triggering of brakes. The latter is carried out in particular when there is not sufficient time for a corresponding user intervention.The accuracy of the TTC calculation depends on the accuracy of the input data, such as the position and speed of the objects. In addition, the TTC may be less reliable in situations with complex motion patterns or sudden changes in speed or direction. The present invention makes it possible in its embodiments to take this into account.The implementation of corresponding methods typically comprises one or more sensors (e.g. radar), inertial sensor systems for transmitting the own movements (yaw rates) to the associated radar sensors of the detection arrangement 11 and a control device 15 of the vehicle 1 for evaluating the objects 2 detected by the sensors and for calculating the variables relevant for triggering the warning or for the intervention.If an obstacle, for example a person, a vehicle or a wall, is detected by a sensor system or a corresponding detection arrangement 11 in collision avoidance methods, the TTC can be determined on the basis of the detected distance from the obstacle and its relative speed. Furthermore, it is possible to distinguish, on the basis of an expected reaction time of the driver, whether or not there remains enough time for a braking intervention of the driver. In the former case, the driver can only be warned, in the latter case an automated braking intervention can take place by the vehicle.The real deceleration behavior of the vehicle 1 in an intervention for collision avoidance is not known in every situation. In practice, the real deceleration behavior is influenced by influencing factors such as road gradient and underlying surface condition, also e.g. a wet or snow-covered road, the mass of the vehicle 1 (i.e. empty mass with or without an available loading), a machine-specific deceleration behavior (hydrostatic, deviating behavior in specific operating modes).The stated influencing factors can lead to the vehicle 1 delaying more than predicted in certain situations during an intervention for collision avoidance. The resulting, significantly reduced vehicle speed can result in the collision-relevant object 2 exceeding the critical predicted time for collision again and the intervention for collision avoidance being released. Upon reacceleration of the vehicle 1, the loop restarts from intervention for collision avoidance and removal of the intervention by the unexpectedly high vehicle deceleration. This vehicle behavior is primarily unpleasant for the driver and cannot be understood. In addition, a strong reacceleration of the vehicle after an intervention for collision avoidance in the case of low-critical objects in the monitored region can lead to a renewed intervention for collision avoidance not occurring in good time on account of the inertia of the hydrostatic travel drive and a collision resulting therefrom.Two partial problems must therefore be solved, namely (1) the detection of low-critical objects in the monitored region at the time end of an intervention for collision avoidance, and (2) a limitation and release of the accelerator pedal for the case described in (1) in order to avoid strong reacceleration.Embodiments of the present invention solve these problems with the proposed collision avoidance method. The vehicle 1 is braked during a braking period if a collision-relevant object 2 is detected in a collision monitoring area 3. However, in the proposed method, only a conditional release of a reacceleration of the vehicle 1 takes place during a release period after the braking period.The limited release of the reacceleration is carried out in the proposed method only when the collision-relevant object 2 is determined as a less critical collision-relevant object 2 (see above in this regard), and a limitation of the reacceleration at the beginning of the release period is carried out at least when the collision-relevant object 2 continues to be detected in the collision monitoring region 3.The proposed method comprises a system or means for detecting low-critical objects 2 in detection area 12 at the end of an intervention for collision avoidance on the basis of the TTC. If an object is detected accordingly, in the proposed method, an initial limitation of the acceleration, for example an accelerator pedal position, is predefined in particular in accordance with the current speed of the vehicle 1. Starting from this initial limitation of the accelerator pedal, the accelerator pedal or another acceleration control device can be released, for example, via a ramp. In corresponding embodiments, this prevents both unnecessary further deceleration of the vehicle 1 and undesired strong acceleration of the vehicle 1 in the described situation.In other words, embodiments of the present invention comprise the classification of an object as "critical" or "less critical", in particular exclusively via the TTC. Differentiation between types of objects such as humans, vehicles, animals and the like is not essential to the invention, but can nevertheless be provided additionally in embodiments of the invention.Under-critical objects can therefore meet all the criteria of a critical object, but still have a TTC that is too high in the current state to trigger a reaction.However, low-critical objects are highly likely to transition into critical objects at a later point in time when their TTC falls further.The aim is now a "prestress" of the system via a stepwise release (ramp) of the reacceleration in the event of the presence of a low-critical object at the end of an intervention for collision avoidance, in order to prevent a strong acceleration. As already stated, this causes the probability of a collision with the less critical object to be reduced by a strong reacceleration, and a repeated jump, which is inconvenient and not comprehensible to the driver, between an intervention for collision avoidance and the release of the accelerator pedal is prevented.This is illustrated again with reference to FIG. 2, which illustrates the speed profiles of collision avoidance systems according to a configuration not according to the invention and a configuration proposed here in a common diagram 200, in which a speed is plotted on a vertical axis versus a time on the horizontal axis.Up to a point in time 201, a vehicle 1 travels at a constant speed in the configuration not according to the invention and in a configuration proposed here, as illustrated by 210. From the time 201 to a time 202, i.e. a braking period, a braking takes place which can likewise take place with an identical deceleration in the embodiment not according to the invention and in an embodiment proposed here, as illustrated by 220.In a configuration not according to the invention, the full acceleration is now released again after the braking period, i.e. from the time point 202, so that, as illustrated by 230, a new braking intervention takes place from a time point 203. This cycle is run through once more, i.e. the acceleration is released again and a braking intervention is carried out again at a time 204.In one embodiment proposed here, instead, the full acceleration is not yet released again after the deceleration period, i.e. from the point in time 202, so that, as shown by 240, initially at most a gentle acceleration takes place. From a point in time 205, a braking intervention to a standstill again takes place.FIG. 3 shows aspects of a collision avoidance system in simplified form in the form of a block diagram 300. A collision avoidance system 310 outputs suitable signals 311 and 312 which, on the one hand, initiate an intervention for collision avoidance and, on the other hand, identify an object 2 as a low-critical object 2. These are transmitted to a block 301, which includes a block 330 for state recognition of the limitation of an accelerator pedal. This may include a limiting state in the form of a signal 331 to a block 340 for limiting or releasing the accelerator pedal, which may output a signal 341. The limitation or release can be carried out on the basis of a signal 313 of the collision avoidance system 310, which signal can indicate that the object 2 is still located in the monitored zone. A signal 321, for example a CAN bus 320, may convey the vehicle speed.FIG. 4 shows a simplified illustration of a collision avoidance method. The method is designated as a whole as 400.In a method step 410 in which a vehicle 1 moves forward at a specific speed, for example, an object 2 is detected in a collision monitoring area 12.In response, in a method step 420, a braking of the vehicle 1 is initiated, namely for a predetermined period of time, referred to here as a braking period of time, which is defined on the basis of, for example, a predetermined time until collision.After the end of the deceleration period, a reacceleration of the vehicle 1 is conditionally enabled in a method step 430, wherein the enabling 430 of the reacceleration is carried out under the condition that the collision-relevant object 2 is now determined, in particular on the basis of the TTC as explained above, as a less critical collision-relevant object 2, and a limitation of the reacceleration is carried out at the beginning of the enabling period at least if the collision-relevant object 2 is still detected in the collision monitoring region 3.The limitation of the reacceleration at the beginning of a corresponding release period can be carried out using a reacceleration limiting value which is raised during the release period until the limitation is canceled in a step 440, the object 2 has moved out of the collision monitoring region 3 or the vehicle 1 has come to a standstill.

Claims

A collision avoidance method (400) comprising: braking (420) a vehicle (1) during a braking period when a collision relevant object (2) is detected in a collision monitoring area (12), and conditionally enabling (430) re-acceleration of the vehicle (1) during a enabling period after the braking period, wherein the enabling (430) of the re-acceleration is performed on the condition that the collision relevant object (2) is determined as a less critical collision relevant object (2), and wherein a limitation of the re-acceleration is performed at the beginning of the enabling period at least when the collision relevant object (2) is further detected in the collision monitoring area (3).The collision avoidance method (400) of claim 1, wherein the limitation of reacceleration at the beginning of the release period is made using a reacceleration limitation value that is incremented during the release period.Collision avoidance method (400) according to either claim 1 or claim 2, wherein a time until a collision with the collision-relevant object (2) is predicted and the collision-relevant object (2) is detected as a less critical collision-relevant object (2) if the predicted time until the collision is above a threshold value.The collision avoidance method (400) of any preceding claim, wherein the enabling (120) of the reacceleration is performed as enabling (120) an acceleration operation unit operated by a driver of the vehicle or an acceleration request signal.The collision avoidance method (400) of any preceding claim, wherein the limitation of reacceleration is made at the beginning of the clearance period based on a speed of the vehicle.The collision avoidance method (110) according to any one of the preceding claims, which is performed in a mobile work machine as the vehicle (1).Collision avoidance system, comprising: a control unit (11) which is configured to brake (420) a vehicle (1) during a braking period when a collision-relevant object (2) is detected in a collision monitoring area (3), and which is configured to conditionally enable (430) re-acceleration of the vehicle (1) during a release period after the braking period, wherein the control unit (11) is configured to enable (430) re-acceleration of the vehicle (1) under the condition that the collision-relevant object (2) is determined as a low-critical collision-relevant object (2), and wherein the control unit (11) is configured to limit the re-acceleration at the beginning of the release period at least when the collision-relevant object (2) is still detected in the collision monitoring area (3).Computing unit, in particular control device (15), comprising a processor which is configured to execute the method according to one of the preceding claims.A computer program comprising instructions which, when the computer program is executed by a computer, cause the computer to execute the collision avoidance method (400) of claims 1 to 8.Computer-readable data medium on which the computer program according to Claim 9 is stored.

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