METHOD AND SYSTEM FOR AVOIDING TRAFFIC COLLISIONS
The invention relates to a method of avoiding collisions between a first unit of traffic and other units of traffic and to a mobile collision warning system set up for this purpose.
Collision accidents in road, water-borne and aerial traffic occur when the paths of two units of traffic cross and both are at the crossing point at the same point in time. It is true that a collision could be avoided by a change in the paths along which the units of traffic are moving prior to the accident, but this is often not done due to limited visibility or inattentiveness on the part of the units of traffic involved.
To reduce the risk of collisions, various automatic auxiliary systems have been developed. In this way, control systems are in use, particularly for air traffic, in which the flight paths of aircraft are detected by radar and monitored at a central point. If there is found to be a risk of collision, the aircraft involved are directed to change their courses by the central point. Also, in the automobile field, there are schemes under development in which the distances between vehicles are measured, by radar for example, and the vehicles are controlled automatically for distance. What is more, there is known from US 5,900,814 a collision warning system in which a detector in a motor vehicle recognizes a hazard situation, such as sudden braking for example, and then emits an alarm signal by radio. This alarm signal can be received by other vehicles having a similar collision warning system so that their drivers can be made aware of the hazard situation on the route they are traveling along. As an option, a system of this kind may also be fitted with a GPS system to enable the location of the unit of traffic giving the warning to be communicated as well. It is however a disadvantage that the system does not go into action until there has already been an initial reaction (such as sudden braking for example) to a hazard situation.
Against this background, it is an object of the present invention to provide a method and a system for avoiding collisions between units of traffic that, with the least possible cost and complication in terms of infrastructure, will help to avoid collisions even when they take place from the normal flow of traffic.
This object is achieved by a method having the features given in claim 1 and by a mobile collision warning system having the features given in claim 7. Advantageous embodiments are detailed in the dependent claims.
The method according to the invention is used for avoiding collisions between a first unit of traffic and other units of traffic. The units of traffic may in particular be motor vehicles, cyclists and/or pedestrians, though in principle the method can also be applied to water-borne vehicles and aircraft. The method comprises the following steps: a) All the units of traffic involved determine their individual current position in space. This may for example be done by means of GPS receivers (GPS = Global Positioning System) that the units of traffic carry with them. b) Each of the "other units of traffic", and preferably the first unit of traffic as well, emits (by radio for example) warning signals which reproduce at least an item of information on the current position in space of the emitting unit of traffic. To enable a distinction to be made between the warning signals originating from different units of traffic and to allow them each to be assigned to a unit of traffic, the warning signals are preferably provided with an unambiguous identifier for the emitting unit of traffic. c) The first unit of traffic considered receives the above-mentioned warning signals from the other units of traffic and on the basis of the data contained therein calculates in advance whether there is a risk of a collision between it and the other units of traffic. Hence, it is possible by the method explained above for the traffic flow in the area surrounding a unit of traffic to be observed and for the risk of any collision to be recognized, thus enabling the risk to be reacted to in the appropriate way. The method manages without a permanently installed infrastructure along the routes followed by traffic, because all the requisite activities are carried out in a self-contained manner by the units of traffic involved. What is of particular advantage is that the collision avoidance operates even when, and precisely when, the traffic flow is normal, because warning signals are exchanged between the units of traffic continuously. For this, it is not a precondition that an exceptional situation (heavy braking or the like) must already have occurred.
For the method to be performed, it is in principle enough if the first unit of traffic carries out only steps a) (determination of its own position) and c) (evaluation of the warning signals from other units of traffic), while the other units of traffic carry out only steps a) (determination of their own positions) and b) (emission of warning signals containing their own positions). It is true that when this is the case it is only the first unit of traffic considered that can predict a risk of collision, but the other units of traffic also benefit from
this indirectly because, for a collision to be avoided, it is enough if only one of the units of traffic involved reacts in the appropriate way. In particular, it is conceivable for units of traffic such as pedestrians or cyclists to carry out only steps a) and b), which is possible with relatively little in the way of equipment, whereas in motor vehicles all the steps a) to c) are carried out. The maximum safety will be achieved however if all the units of traffic involved carry out all the steps, a), b) and c).
From the continuously received warning signals from other units of traffic, the receiver can itself work out their positions and also the higher derivatives with respect to time of the positions (speed, acceleration, etc.). In a preferred embodiment of the method however, the warning signals that are emitted in step b) contain not only the position in space of the unit of traffic but also the first derivative with respect to time of this position in space, i.e. the velocity of movement in space (vector) of the unit of traffic. A knowledge of the velocity of a unit of traffic is helpful for predicting whether there is going to be a collision with it. Even better prediction of a collision is possible if, in addition to this, the warning signals also contain even higher derivatives with respect to time of the position in space. This applies particularly to the second derivative of the position in space, i.e. the acceleration of the unit of traffic. A knowledge of the acceleration also makes it possible for braking by a unit of traffic, and hence an indicator of an existing hazard situation, to be detected.
It is also of advantage if the warning signals emitted in step b) contain information on the course the emitting unit of traffic is planning to follow. In this way, items of information that do not originate simply from the instantaneous data on the movement of the unit of traffic can be allowed for in the advance calculation of a potential collision. These items of information may include, in particular, planned changes of speed (accelerations, decelerations), stopping operations and turn-off operations. It is particularly preferable if the items of information also include the intended route, in which case reference may for example be made to a digital map. In this way, an imminent change of direction due to a bend in the road can be detected and allowed for in good time.
If in step c) there is found to be a risk of a collision, this can be reacted to in various ways. In the simplest case, a visual and/or audio warning is given to the first unit of traffic to draw its attention to the threat of a collision and to give it an opportunity of making an avoiding maneuver in good time.
What is more, in the event of a threat of a collision, the movement of the first unit of traffic may also be changed automatically. In particular, a motor vehicle may be automatically braked to prevent the collision or keep the damage to a minimum.
Finally it is also possible, in the event of a threat of a collision, for alarm signals that indicate this danger to be sent to the rest of the units of traffic. In this way, the other units of traffic too will have their attention drawn to the danger to enable the danger to be overcome by coordinated action. Alarm signals of this kind may also be emitted if, in step c), the first unit of traffic considered detects the risk of a collision between other units of traffic though would not itself be involved in this threatened collision. The other units of traffic can then react to avoid the collision even if they have not yet recognized the risk of collision themselves or are not, in principle, themselves in a position to recognize the risk of collision. The invention also relates to a mobile collision warning system that comprises the following elements: a position-determining unit that makes it possible for the current position of the collision warning system in space to be determined, a transmitter to broadcast warning signals, which may in particular be a radio transmitter, a receiver to receive warning signals from other collision warning systems, a control unit that is connected to the position-determining unit, the transmitter and the receiver and that is set up to generate warning signals with the help of the signals supplied by the position-determining unit and to broadcast these warning signals via the transmitter, the warning signals reproducing in particular the current position in space of the collision warning system. The control unit is also set up to determine from the warning signals from other collision warning systems received by the receiver the positions of said other collision warning systems and to predict therefrom a threatened collision (between at least two of the collision warning systems involved). With the collision warning system described, it is possible for the method explained above to be carried out. The advantages this gives of simple, decentralized prevention even of collisions taking place from the normal flow of traffic can thus be obtained by means of the collision warning system. It is particularly advantageous that the collision warning system manages with only a few components, thus enabling it to be relatively light and inexpensive. It is therefore possible even for pedestrians or cyclists to carry a collision warning system of this kind with them, thus enabling improved protection to be obtained even for these units of traffic, who are particularly at risk.
The collision warning system is preferably so arranged that it can also perform the variants of the method that are explained above. In particular, the control unit and/or the
position-determining unit may be capable of determining at least the first derivative with respect to time of the position in space and of adding it to the warning signals. The control unit may further be set up to add information on the planned course of the collision warning system to the warning signals. For this purpose, the control unit is advantageously provided with access to a digital map and/or to a navigation system. Furthermore, the collision warning system may be connected to means for issuing a visual and/or audio warning to the user of the collision warning system. Finally, the collision warning system may be coupled to an actuator that can actively intervene in the control of the vehicle that is carrying the collision warning system. The position-determining unit preferably contains a GPS receiver to enable the absolute position of the collision warning system in space to be determined.
In another embodiment of the collision warning system, the system contains a memory for recording signals of different kinds and in particular signals from the position- determining unit and/or warning signals that have been received from other units of traffic. This memory thus forms a journey recorder that allows the causes to be analyzed after an accident.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
In the drawings:
Fig. 1 shows in diagrammatic form the components of a collision warning system according to the invention in a motor vehicle, cooperating with a second collision warning system carried by a pedestrian. In Fig. 1 , there is shown firstly a motor vehicle 9 that contains a collision warning system 1. The collision warning system 1 comprises in turn essentially the following components:
A transmitter or transponder 3 that can emit warning signals into the surroundings by, for example, radio. The transponder can be manufactured and sold as an inexpensive mass-produced battery-based product. Similarly, the possibility exists of the relevant function being incorporated in a mobile telephone.
A receiver 4 that is able to receive warning signals emitted by other collision warnings systems 1' and pass them on to a control unit 2.
The control unit 2 mentioned above, in the form of a microprocessor for example, that processes the warning signals or information received from the receiver 4 and converts them or it into control signals to different actuators.
A position-determining unit 5 that determines the current position of the motor vehicle 9, or rather the collision warning system 1 , in space.
If required, the blocks representing the transmitter 3 and the position- determining unit 5 that are shown in the Figure may be integrated into one module.
The transponder 3 transmits at least the following items of information omnidirectionally into its surroundings at regular intervals that are randomly set and follow one another in short succession: an identifier for the transmitting collision warning system 1 , the current position of the collision warning system 1 in space, a speed vector (i.e. the speed of movement of the motor vehicle 9 in space by direction and amount) and, if required, an acceleration vector (derivative of speed with respect to time).
A possible implementation of the transponder 3 and the position-determining unit 5 may comprise a GPS receiver having processing logic that determines the appropriate data to be transmitted and transmits it by means of any desired radio technology, such as by means of Bluetooth Beacon for example. Similarly, the function of the transponder 3 may also be incorporated in a mobile telephone, in which case the determination of position may be carried out by triangulation for example.
It should be pointed out that a simplified version of the collision warning system 1 may also comprise simply a transmitter 3 and a position-determining unit 5. This makes the system correspondingly smaller and cheaper, thus enabling it to be carried with them even by pedestrians and cyclists. A simplified collision warning system of this kind simply transmits its own position continuously to other units of traffic and indirectly benefits from the fact that, with the help of this data, the latter carry out active collision prediction and avoidance.
The receiver 4 represents a receiving system that is based on the same (radio) technology as the transponder 3 and that is capable of receiving warning signals from other transponders transmitted in the fairly close surrounding area. What is shown in this regard in the Figure is a pedestrian 10 who is carrying another collision warning system 1' with him. The warning signals emitted by this are received by the receiver 4 and passed on to the control unit 2.
The control unit 2 contains the decision-making logic that processes the information from the receiver 4 together with data from the position-determining unit 5 conveying information (position, speed, direction, acceleration) on its own movement. By means of known algorithms, potential collisions can be recognized from this information. The control unit 2 can then pass on appropriate control commands to the actuators described below.
The actuator block 8 represents a driver warning system and comprises a filter and an output unit. In line with external settings, the filter assesses which of the items of collision information passed on by the control unit 2 can be disregarded. The items of information that are not disregarded are passed on to the output unit, which generates a visual or audio warning for the driver of the danger that exists.
The actuator block 7 represents an emergency system comprising a filter and an activation unit. In line with external settings, the filter assesses which of the items of collision information passed on by the control unit 2 can be disregarded. The items of information that are not disregarded are passed on to the activation unit. The latter generates control information to allow the collision to be avoided or its consequences to be made less severe. The activation unit may for example generate a deceleration vector for the braking system of the motor vehicle 9 to enable the speed of the latter to be changed in a defined manner, or it may generate a series of control pulses for the control system of the vehicle 9 to cause an avoidance maneuver to be performed.
Finally, the collision warning system 1 also contains a memory 6 that acts as a journey recorder and stores the information passed on to it in a non- volatile form. The data can then be used for a later analysis of an accident if such an analysis is required.
All the components described above can be installed in motor vehicles and, for the avoidance of accidents, can be coupled to the X-by-wire systems that are known today or will be incorporated in the near future - i.e. systems where all the safety-related functions in the automobile such as for example steering, braking, accelerating, etc. are handled via networks (see "fly-by-wire" in aircraft).
Thus, the collision warning system that has been elucidated is based on the fact that it transmits information on position and speed vectors continuously into the surroundings to enable a "map" of all the objects in the surroundings and their movements to be constructed in any other collision warning system. Any desired applications can then make use of the relevant information. A warning light may be switched on for example or, in the context of active safety, a car may be automatically braked or steered in a given direction, to
allow accidents to be avoided. Pedestrians can be warned by a pocket receiver in their telephone when for example a car is approaching a zebra crossing too fast and can no longer brake safely. List of reference numerals
1 Collision warning system r Collision warning system
2 Control unit
3 Transmitter
4 Receiver
5 Position-determining unit
6 Journey recorder
7 Actuator
8 Display
9 Motor vehicle
10 Pedestrian