WARNING SYSTEM FOR REAR END VEHICLE COLLISIONS

Abstract: A warning device for rear end vehicle collisions (10) comprising a radar (12) attached to a rear of a vehicle (A) and directed to determine the range of a following vehicle (B) and to activate a warning alarm (36, 40, 42) when the distance and/or speed of approach of the following vehicle (B) are not outside a nominally safe distance and/or speed of approach determined by a signal processor (22) of the warning device (10). The warning alarm (36, 40, 42) is first activated to warn (40) a driver of the following vehicle (B) and then to warn (42) a driver of a leading vehicle (A). The invention also relates to a vehicle (A) having the warning device (10) fitted to it.

Description: TITLE "WARNING SYSTEM FOR REAR END VEHICLE COLLISIONS" DESCRIPTION The present invention relates to a warning system for rear end vehicle collisions. FIELD OF THE INVENTION In the past attention has been given to development of headway vehicle collision warning systems with the object of warning a driver of a vehicle when an obstacle appears in front of the vehicle for example another vehicle, or pedestrian, or a cyclist or an animal or the like. Such systemsare often intended to be coupled to an automatic breaking system or an automatic air bag activator or the like, with the possible ultimate objective of an automated highway. The major problem with headway warning systems is that of radar returns from unwanted ta>rgets, such as signs and sign posts, overhead bridges, metal debris on the road and the like. The unwanted returns lead to false alarms and to failed detections. The problem stems from the fact that most targets, even where stationary, appear to be approaching the vehicle. The aim of the present invention is to reduce the incidence of rear end vehicle collisions and hence the occurance of whiplash and neck injuries caused thereby. Rear end collisions have been found to be the most frequent type of inter vehicle collision. The main reason for the frequent occurance of such collisions is that following vehicles tend to allow an insufficient safety distance to a leading vehicle. Generally, the driver of the following vehicle adopts a safety distance that feels safe based on his or her experience with the vehicle and the predominate weather conditions. However, where road conditions are adverse and/or the driver of the following vehicle experiences a lapse in concentration or is distracted the adopted distance may not be sufficiently safe and a rear end collision may occur with the leading vehicle. SUMMARY OF THE INVENTION The present invention provides a warning system for rear end vehicle collisions to provide a warning to a driver of a following vehicle and/or a leading vehicle that the following vehicle is likely to collide with the leading vehicle unless evasive action is taken by one or both of the drivers. In accordance with one aspect of the present invention there is provided a warning system for rear end vehicle collisions characterised in that it comprises a ranging mean arranged to be attached to the rear of a vehicle and disposed to determine the distance to a following vehicle, a signal processor configured to determine a safe distance of approach for the following vehicle and an alarm means to be activated when the distance of approach of the following vehicle is not outside the safe distance determined by the signal processor. In accordance with a further aspect of the present invention there is provided a vehicle characterised in that it comprises a front, a rear, a ground engaging steering wheel and a warning system for rear end vehicle collisions comprising a ranging means attached to the rear of the vehicle and disposed to determine the distance to a following vehicle, a signal processor configured to determine a safe distance of approach for the following vehicle and an alarm means to be activated when the distance of approach of the following vehicle is not outside the safe distance determined by the signal processor. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is functional block diagra m of a warning system for rear end vehicle collisions in accordance with the present invention; and Figure 2 is a schematic representation of a vehicle comprising the warning system of Figure 1 and shown in use. DESCRIPTION OF THE INVENTION In Figure 1 there is shown a warning system for rear end vehicle collisions 10 comprising a ranging means 12 having a transmitter antenna 14 and a receiver antenna 16 arranged to be attached to the rear of a vehicle A as shown in Figure 2. The transmitter antenna 14 and the receiver antenna"16 may be formed as a single antenna. Preferably, the antenna is of a relatively small construction so as to readily allow for installation in vehicles being compact cars. For example, a Mills Cross Antenna could be used, thus achieving a composite beam width of 2°x2° with a V-shaped antenna. Further,it is envisaged that 45° polorization may be used to reduce interference at the receiver antenna 16 from targets adjacent the target immediately following the vehicle A, such as for example, vehicles in adjacent lanes of traffic. Preferably, the ranging means 12 comprises a steer means (not shown) arranged to steer a beam transmitted from the transmitter antenna 14. The steer means could produce a mechanical steering of the transmitter antenna 14 and/or an electrical steering of the beam pattern produced by the transmitter antenna 14. Steerage of the beam from the transmitter antenna 14 is preferred to enable the warning system 10 to allow for curvature in roads upon which the vehicle A travels. The ranging means 12 also comprises radar sensor 17 having a transmitter 18 connected to drive the transmitter antenna 14 and a receiver 20 connected to receive signal collected by the receiver antenna 16. The ranging means 12 may conveniently operate at microwave frequencies such as for example the K-band (17-25 GHz) or the Ku-band (25-40 GHz). Generally, use of higher frequencies is preferred in order to improve discrimination of the target and allow for use of smaller antenna. However, where the frequency is too high weather condititons may adversely affect there-Liabilityand accuracy of the ranging means 12. It has been found that to reduce the effects of weather conditions on the performance of the warning system 10, • especially backscatter caused by rain and attentuation caused by adhesion of snow ice or water to a radome of the transmitter and receiver antenna 14 and 16, the antenna 14 and 16 require a high gain. It is envisaged that the ranging means 12 operate on a Doppler principle where the signal received by the receiver 20 is slightly frequency shifted from that which was transmitted. The frequency shift is then proportioned to the radial velocity of a target, relative to the transmitter 18, such as a following vehicle B, as shown in Figure 2. The warning system 10 also comprises a signal processor 22 having an output 24 to the transmitter 18 and an input 26 from the receiver 20. The signal processor 22 comprises an initiator (not shown) to periodically send an activating signal from the output 24 to the transmitter 18 to cause it to transmit a ranging signal. The signal processor 22 also comprises a frequency counter (not shown) connected to the input 26 and configured to determine the frequency shift which has been introduced into the received signal by the moving following vehicle B and hence the velocity of the vehicle B toward the vehicle A. The warning system 10 also comprises a vehicle status means 28 having an output 30 to the signal processor 22. The vehicle status means 28 comprises a vehicle speed measuring means to measure the speed of the vehicle A, an angle measurement means to measure the angle of a ground engaging steering wheel of the vehicle A and a brake sensor to sense application of brakes of the vehicle A. The angle measurement means is connected to the steer means to steer the beam produced by the transmitter antenna 14 to compensate for road curvatures. The signal processor comprises a range calculation means (not shown) configured to determine a safe distance and/or a safe speed of approach for the following vehicle B. The determination of the safe distance and/or safe speed of approach principally based on the measured velocity of the vehicles A & B and the estimated braking deceleration of which the vehicles A & B are capable. The determination of safe distance of approach and the instantaneous distances of approach may conveniently be expressed as follows: R where R = safe distance of approach Vo - actual velocity of vehicle A. Vr - actual velocity of vehicle B. b^ - braking deceleration of vehicle A. b - braking deceleration of vehicle B. Vo-Vr = relative velocity measured by the ranging means 12. The warning means 10 also comprises an adjustment means 32 connected to the signal processor 22 by an output 24. The adjustment means 32 is arranged to be adjusted by a driver of the vehicle A to compensate the determination of the safe distance of approach for prevailing road conditions such as weather and qualityof road and/or visibility and the estimated driver reaction time. The former is used to modify the estimated values of braking deceleration capable of the vehicles A & B. The latter is used to increase the value of safe distances by adding a term which is the product of the velocity (Vo) of the vehicle A and the reaction time (TR) of the driver of the vehicle A, namely TRVQ. The reaction time Tr is expected to be based on the experience and the age and the like of the driver. The warning means 10 may also comprise a range rate means configured to count beats produced by the. interference • of the frequency shifted received ranging signal ' with the transmitted ranging signal or by differentiating the determination of range to the following vehicle B with respect to time. The range rate means thus determines the rate of charge of the distance to the following vehicle B and is used to determine a safe speed of approach thereof. The range rate means also serves to provide a check of the range determinations. The warning means 10 also comprises an alarm means 36 connected to an output 38 of the signal processor 22. The alarm means comprises a visual alarm 40 (Figure 2) arranged to be located adjacent the rear of the vehicle A and in view of the driver of the following vehicle B. The alarm means 36 is activated by the signal processor 22 to operate the visual alarm 40 when the distance and/or speed of approach of the following vehicle B is not outside the determined safe distance and/or the safe speed of approach so as to provide a warning to the driver of the following vehicle B. It is intended that the driver of the following vehicle B then act upon the warning toattempt to avoid a collision. The alarm means 36 also comprises an audio and/or visual alarm 42 arranged to be located adjacent a front of the vehicle A and in hearing range and/or in view of the driver of the vehicle A. The alarm means 36 is activated by the signal processor 22 to operate the audio and/or visual alarm 42 when the distance and/or speed of approach of the following vehicle B continues to be not outside the determined safe distance and/or the safe speed of approach, so as to provide a warning to the driver of the vehicle A. The audio and/or visual alarm 42 is thus activated after the visual alarm 40 and so the driver of the vehicle A is given an ultimate warning of a collision.so as to take action to brace himself or herself to avoid neck injury which is otherwise generally associated with surprise rear end collisions. In use, the warning system 10 of the present invention is installed into a vehicle A. The antennae 14 and 16 are attached to the rear of the vehicle A. The visual alarm 40 is attached to the vehicle A adjacent the rear and disposed in a rearward direction to be viewed by a driver of a following vehicle B. The audio and/or visual alarm 42 is attached adjacent the front of the vehicle A and disposed rearwardly to be heard and/or viewed by the driver of the vehicle A. Connections are then made to attach the vehicle status means 28 to the vehicle A. Before driving the vehicle A the driver enters details such as his or her age and experience into the adjustment means 22. The date used by the adjustment means 32 to determine the likely reaction time TR of the driver. The reaction time TR is sent to the signal processor 22 via the output 32 in order to adjust the determination of safe distances and/or safe speed for the following vehicle B. The driver also enters into the adjustment means 32 the prevailing road and weather condition. These conditions are used, ad described hereinabove, to adjust the determination of safe distances and/or safe speed or approach. At installation the signal processor 22 is set for the braking deceleration generally found in the make and model of vehicle to which the warning system 10 is attached. Also, an estimate of an average braking deceleration for likely following vehicle B is also set into the signal processor 22. When driving along the initiator in the signal processor 22 periodically activates the transmitter 18 which in turn transmits a ranging beam to be radiated by the transmitter antenna 14. Where a target such as the vehicle B is present behind the vehicle A the ranging signal is reflected by the vehicle B back to the receiving antenna 16. The frequency counter in the signal processor 22 measures the frequency change in the ranging signal and hence the relative approach velocity of the following vehicle B. The distance to the following vehicle is determined by the signal processor 22 using the expression for R. The range rate is also determined by the range rate means as described hereinabove. When the distance and/or the speed of approach is not outside the safe distance and/or safe speed of approach the signal processor 22 first activates the alarm means 36 to operate the visual alarm 40 to warn the driver of the following vehicle B so that he/she may take appropriate action. When the distance and/or the speed of approach continues to be not outside the safe distance and/or safe speed of approach the signal processor 22 then activates the audio and/or visual alarm 42 to warn the driver of the vehicle A to brace himself or herself. Where no vehicle is following the vehicle A the receiver 20 does not receive a return ranging signal. When the vehicle A turns a bend in a road the angle measurement means in the vehicle status means 28 determines the angle of deflection of the steering wheels of the vehicle and produces a corresponding steering of the ranging beam. It is envisaged that once a vehicle is detected as following the vehicle A that the ranging means 12 and the signal processor 22 only search for targets at or about that range in a range gate type technique. Thus, the warning system 10 of the present invention provides a two stage warning to attempt to avoid rear- end vehicle collisions. Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.

Claims: CLAIMS 1. A warning system for rear end vehicle collisions characterised in that it comprises a ranging means arranged to be attached to the rear of a vehicle and disposed to determine the distance to a following vehicle, a signal processor configured to determine a safe distance of approach for the following vehicle and an alarm means to be activated when the distance of approach of the following vehicle is not outside the safe distance determined by the signal processor. 2. A warning system for rear end vehicle collisions according to claim 1, characterised in that it comprises a range means to determine the rate of charge of the distance to the following vehicle, the signal processor being configured to determine the safe distance and a safe speed of approach for the following vehicle based on the range and the range rate and the alarm means being activated when the distance and the speed of approach of the following vehicle are not outside the safe distances and the safe speed determined by the signal processor. 3. A warning system for rear end vehicle collisions according to claim 1 or 2, characterised in that the alarm means may comprise a visual alarm located adjacent the rear of the vehicle and arranged to be in view of a driver of the following vehicle. 4. A warning system for rear end vehicle collisions according to claim 3, characterised in that the alarm means comprises an audio and/or visual alarm arranged to be in hearing range and/or in view of a driver of the vehicle, the audio and/or visual alarm being configured to be activated after the visual alarm located adjacent the rear of the vehicle is activated. 5. A warning system for rear end vehicle collisions according to any one of the preceding claims, character¬ ised in that the processor means comprises an adjustment means to compensate the processormeans in the determination of the safe distance and speed for prevailing road conditions. 6. A warning system for rear end vehicle collisions 5 according to claim 5, characterised in that the adjustment means also allows for compensation of the processor means in determination of the safe distance and speed for the reaction time of the driver of the vehicle. 7. A warning system for rear end vehicle collisions 10 according to any one of the preceding claims, characterised in that the ranging means comprises an antenna and means to steer a beam transmitted by the antenna to compensate for curvature in roads upon which the vehicle travels. 8. A warning system for rear end vehicle collisions ∑5 according to claim 7, characterised in that it comprises an angle measurement means to determine the angle of a ground, engaging steering wheel of the vehicle, the angle measurement means being arranged to steer the beam transmitted by the antenna to compensate for curvature 20 in roads upon which the vehicle travels. 9. A vehicle characterised in that it comprises a front, a rear, a ground engaging steering wheel and a warning system for rear end vehicle collisions comprising a ranging means attached to the rear of the vehicle and 25 disposed to determine the distance to a following vehicle, a signal processor configured to determine a safe distance of approach for the following vehicle and an alarm means to be activated when the distance of approach of the following vehicle is not outside the safe distance 30 determined by the signal processor. 10. A vehicle according to claim 9 characterised in that the warning system for rear end vehicle collisions comprises a range rate means to determine the rate of change of the distance to the following vehicle and the 35 signal processor being configured to determine the safe distance arid a safespeed of approach for the following vehicle based on the range and the range rate and the alarm means being configured to be activated when the distance and the speed of approach of the following vehicle are not outside the safe distance and the safe speed determined by the signal processor. 11. A vehicle according to claim 9 or 10, characterised in that the alarm means comprises a visual alarm located adjacent the rear of the vehicle and in view of a driver of the following vehicle. 12. A vehicle according to claim 11, characterised in that the alarm means comprises an audio and/or visual alarm located adjacentthe front of the vehicle and in hearing range and/or in view of a driver of the vehicle, the audio and/or visual alarm being configured to be activated after the visual alarm located adjacent the rear of the vehicle is activated. 13. A vehicle according to any one " of the preceding claims 9 to 12, characterised in that the warning system comprises an angle measurement means to determine the angle of the ground engaging steering wheel of the vehicle, the angle measurement means being connected to steer a beam transmitted by and antenna of the ranging means to compensate for curvature in roads upon which the vehicle travels.

Inventors: ATTIKIOUZEL YIANNI, KUKULAS BYRON ARTHUR, ATTIKIOUZEL, YIANNI, KUKULAS, BYRON, ARTHUR
Applicants: ATTIKIOUZEL YIANNI, KUKULAS BYRON ARTHUR, ATTIKIOUZEL, YIANNI, KUKULAS, BYRON, ARTHUR
Application year: 1986
Main classification: G08B21
IPC codes: B60Q1, G01S7, G01S13