PARKING AID
The present invention relates to a parking aid and particularly, but not exclusively, to an improved parking aid system for a vehicle such as an automobile.
Systems that assist the driver of an automobile to park the vehicle, also known as parking assist systems or parking aids, are well known. Conventionally, these systems comprise a plurality of sensors mounted on the exterior bodywork of the vehicle, usually at the extremities thereof such as on the front or rear bumpers. The sensors are arranged to determine the distance between the vehicle and nearby objects and to warn the driver to take appropriate action in the event that the vehicle moves within a predetermined distance thereof.
The most common systems provided on vehicles are reverse parking aids. The sensors used in these systems are mounted in the vehicle's rear bumper and the system is actuated when reverse gear is selected.
More costly variants provide sensors on both the front and rear bumpers of the vehicle, which are constantly operated whilst the vehicle ignition is switched on and the vehicle is in gear, to warn the driver of nearby objects on all sides of the vehicle.
A disadvantage of such systems is that, owing to their relatively high cost, they are generally fitted only to higher end vehicle models. Lower specification vehicles are generally not provided with these systems. There are therefore many vehicles currently used which are not provided with parking aids. Clearly, not only are these unequipped vehicles more likely to come into collision with objects during reversing or parking and suffer damage but even vehicles which do have such systems fitted also risk being damaged by unequipped vehicles whilst parked in car parks, streets or other built up areas.
It is an aim of the present invention to provide a system that addresses the above disadvantages.
According to one aspect of the present invention, therefore, there is provided a parking aid system for a vehicle comprising sensing means for determining the distance between said vehicle and a second vehicle and alert means for generating an alert signal to the driver of the second vehicle in dependence thereon.
The alert means may comprise means for generating an audible and/or visual signal which is noticeable by the driver of the second vehicle. The alert means may comprise means for illuminating one or more lights of the vehicle. Alternatively or in addition, the alert means may comprise means for activating the vehicle horn.
In one embodiment, the alert means is arranged to generate a first alert signal when the distance between the vehicle and the second vehicle is below a first predetermined distance.
The alert means may also be arranged to generate a second alert signal when the distance between the vehicle and the second vehicle is below a second predetermined distance.
In another embodiment, the alert means may be arranged to alter the alert signal as the distance between the vehicle and the second vehicle decreases.
The system may be arranged for operation when the vehicle ignition is switched off.
The sensing means may be arranged to generate a signal and to transmit the signal away from the vehicle. In the event that the transmitted signal is reflected from a nearby object, the sensing means may be arranged additionally to receive the reflected signal.
The sensing means may include control means for generating an electrical signal. The sensing means may additionally include at least one sensor disposed on the body of the vehicle. A plurality of such sensors may be provided and may be located on the front and/or rear bumper of the vehicle.
The or each sensor may comprise a transducer arranged to convert the electrical signal into an acoustic or electromagnetic signal. The acoustic signal may be an ultrasonic signal. The electromagnetic signal may be a radio signal, a milliwave or microwave signal, a digital radio signal or any other suitable signal.
The or each sensor may be arranged to transmit the acoustic or electromagnetic signal away from the vehicle and to receive the reflected signal.
The control means may be arranged to determine the time interval between transmission of the signal and reception of the reflected signal and to calculate the distance between the vehicle and the second vehicle.
The alert means may include a body control unit of the vehicle which is arranged to control one or more lights of the vehicle and/or the vehicle horn.
The control means may be arranged to communicate with the body control unit thereby to generate the or each alert signal when the distance between the vehicle and the second vehicle is below a predetermined threshold distance.
The system may further comprise proximity sensing means for sensing the presence of an object within a predetermined range of the vehicle and for generating an activating signal in response thereto.
The activating signal may be arranged to activate the control means from a quiescent state thereof, thereby to generate the electrical signal.
According to another aspect of the invention there is provided a method of operating a parking aid system for a vehicle comprising monitoring the distance between the vehicle and a second vehicle and generating an alert signal to the driver of the second vehicle in dependence thereon.
The method may include generating a first alert signal when the distance between the vehicle and the second vehicle is below a first predetermined distance. The method may additionally include generating a second alert signal when the distance between the vehicle and the second vehicle is below a second predetermined distance.
The method may alternatively comprise changing the alert signal as the distance between the vehicle and the second vehicle decreases.
The invention, which may be fitted to a vehicle, advantageously detects when a second vehicle is approaching and, when the distance between the two vehicles falls below a predetermined threshold distance, generates an alert signal which the driver of the second vehicle can detect. The driver of the second vehicle can then take appropriate action to avoid a collision.
The present invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Figure 1 is a schematic block diagram of a known form of parking aid system for a vehicle;
Figure 2 illustrates a vehicle having the system of Figure 1; and
Figure 3 is a schematic block diagram of a preferred form of parking aid system according to the invention;
Referring firstly to Figure 1, a known form of parking aid system for a vehicle is shown in schematic block form generally at 10. The system 10 comprises a plurality of sensors, in the form of acoustic transducers 12, which are disposed in or on the rear bumper 13 of a vehicle, as shown in Figure 2.
The transducers 12 are each electrically connected to respective outputs of a control unit 14 by means of a shielded cable 15. The control unit 14 is powered by the vehicle's battery to which it is connected via the vehicle's ignition switch 16. An input of the control unit 14 is connected to a second switch 18 which is actuable, i.e. closed, when reverse gear is selected within the vehicle. A further output of the control unit 14 is connected to an alert device in the form of a sounder 20.
In use, when the vehicle's ignition is switched on, i.e. the switch 16 is closed, the control unit 14 is also switched on. However, the control unit remains in a quiescent state and is not activated. When reverse gear is selected in the vehicle, the reversing switch 18 is closed causing current to flow from the vehicle battery to the control unit 14 which detects the current and responds by generating an electrical signal which is applied to each of the transducers 12 via the cables 15.
The electrical signal generated by the control unit 14 is in the form of a 40KHz signal which is amplitude modulated to define a train of pulses, each pulse
having a duration of between approximately 1ms and 10ms at intervals of approximately 100ms. This signal is applied to each of the transducers 12 sequentially so that no more than one transducers is being applied with the signal at any one time. Each transducer therefore receives the pulses at the rate of approximately 2.5 times per second, i.e. 2.5Hz.
Each transducer 12 is arranged to convert the electrical signal into an acoustic signal of the same frequency and structure, i.e. that is to say a 40KHz pulse having a duration of between 1ms and 10ms approximately which is repeated at a rate of approximately 2.5 Hz.
The ultrasonic pulses generated by the transducers 12 are radiated away from the vehicle and may be reflected by nearby objects. The reflected signals are received by the transducers during the interval between successive pulses and applied to the control unit 14. It will be understood from the above that the transducers 12 are operable alternately to act as transmitters and receivers.
The control unit 14 determines the time taken between transmission of the ultrasonic pulse and reception of the reflected signal by the transducers 12 and calculates from this the distance between the vehicle and the object from which the acoustic signal was reflected. In addition, the approximate position of the object can be estimated by monitoring the differences in the time delays detected by the different transducers 12 and using a method of triangulation.
This operation is repeated by the control unit 14 such that it continues to apply the pulsed signal to the transducer 12 whilst the reverse gear switch 18 is closed. The transducers 12 convert the signal into an acoustic signal and transmit it away from the vehicle in a series of discrete pulses. During the interval between successive pulses, the transducers 12 detect the reflected ultrasonic signal and the control unit 14 then calculates the distance between the vehicle and the object from which the signal was reflected.
When the distance between the vehicle and the object falls below a predetermined threshold distance, the control unit 14 activates the sounder 20 to produce an audible alert signal. The volume, pitch, tone or structure of the alert signal is then varied by the sounder 20 in dependence on the distance between the vehicle and the object. For example, the control unit 14 may control the sounder 20 to emit a succession of "beeps" which increase in frequency as the distance between the vehicle and the object decreases until, when the vehicle is less than, for example, 0.5 m away from the object, the sounder emits a substantially continuous tone.
The driver can judge the distance of the vehicle from an adjacent object from the nature of the alert signal, in this case from the frequency of the beeps emitted by the sounder 20. When the sounder 20 emits a substantially continuous tone, the driver knows that the vehicle is within 0.5m of the object.
As stated above, such parking aid systems are highly valuable to the driver of the vehicle since they permit easier parking and manoeuvring of the vehicle in small or crowded areas. However, while such systems can help to reduce the likelihood of the driver damaging the vehicle during, for example, parking manoeuvres, they are unable to prevent the vehicle from being damaged whilst parked by other vehicles that do not possess a parking aid system which are parking or manoeuvring close by.
Referring now to Figure 3, a form of parking aid system according to the invention is shown generally at 100. In the described embodiment, the system 100 has all of the features of the system of Figure 1, that is to say a plurality of ultrasonic transducers 112 each connected to a control unit 114 and a sounder 120. An input of the control unit 114 is connected to a reversing switch, which is closed when reverse gear is selected and the control unit 114 is again connected to the vehicle battery via the ignition switch 16.
However, in the illustrated embodiment, the control unit 114 is additionally provided with a permanent connection to the vehicle battery such that it is powered at all times, even when the ignition is off, i.e. the switch 16 is open.
In Figure 3, the system 100 is shown as having four transducers 112. However, this number is optional and it may be preferable to provide a greater number of transducers and to mount these in both the front and rear bumpers of the vehicle.
The system 100 also comprises a microwave proximity sensor 122 which is located on the vehicle and adapted to detect movement of an object within a threshold range around the vehicle. Such sensors, and the operation thereof, will be well understood by those skilled in the art. The microwave proximity sensor 122 is connected to the control unit 114 and is arranged to generate and apply an activating signal thereto in response to the detection of an object within the threshold range.
The control unit 114 is additionally connected to the vehicle's body control unit 124 (BCU) which is arranged to control, amongst other functions, operation of the vehicle's lights and horn. BCUs are commonly provided on modern automobiles and again, therefore, the operation of these devices will be well understood by the skilled person.
The system 100 is operable in two modes and to perform two distinct functions, as described below.
In a first mode, termed the parking assist mode, the system 100 operates in a manner similar to the conventional system of Figure 1. In other words, when the vehicle ignition is on and the vehicle is put into reverse gear, the reverse gear switch 118 is closed and current is applied to the input of the control unit
114. In response to this current, the control unit 114 generates an electrical signal comprising a stream of pulses and applies the electrical signal to the transducers 112. Each transducer 112 converts the electrical signal into an acoustic (ultrasonic) signal, also in the form of a train of pulses, and transmits it away from the vehicle.
The acoustic pulses are reflected by any adjacent or nearby objects and are returned to the transducer. In the interval between each successive pulse, the transducers 112 receive the reflected ultrasonic signal and convert it back into an electrical signal apply it to the control unit 114. The control unit 114 determines the time period between the transmission of the pulse and reception of the reflected signal and then calculates the distance between the vehicle and the object.
The control unit 114 controls the sounder 120 so that it generates an audible signal to the driver of the vehicle when the distance between the vehicle and a nearby object falls below a predetermined threshold distance. The tone, pitch, volume or structure of the alert signal generated by the sounder 120 changes as the distance between the object and the vehicle decreases, as described with reference to the system of Figure 1, in order to assist the driver in parking or manoeuvring the vehicle in close proximity to the object.
In addition, however, the system 100 is operable in a second mode, termed the collision avoidance mode, in which it performs an additional function. This function is at its most effective when the vehicle (hereafter the "subject vehicle") is unattended with the ignition switched off, the control unit 114 still being powered during this time through the permanent connection to the battery, as described above.
Specifically, if the microwave proximity sensor 122 detects the presence of an object such as a vehicle (hereafter the "second vehicle") within the threshold
range, it generates the activating signal which is applied to the control unit 114, activating the control unit from its quiescent state. This occurs irrespective of whether the vehicle ignition is switched on or off.
Once activated, the control unit 114 begins to generate the pulsed electrical signal which is applied to the transducers 112 in the manner described above. The transducers 112 convert the electrical signal into ultrasonic pulses which are transmitted away from the vehicle. The pulses are reflected from the second vehicle and are received by the transducers 112, in the interval between successive pulses, which then apply the reflected signal to the control unit 114.
As in the system of Figure 1, the control unit 114 determines the time period between transmission of the pulse and reception of the reflected signal and calculates the distance between the subject vehicle and the second vehicle. However, in this second mode, when the distance between the subject vehicle and the second vehicle decreases below a first predetermined threshold distance, the control unit 114 communicates with the BCU 124 which generates a first control signal, for example by causing the vehicle hazard lights 126 to flash a predetermined number of times.
If the distance between the two vehicles decreases further, for example below a second predetermined distance, the control unit communicates with the BCU 124 which then generates a second control signal, for example by causing the vehicle hazard lights 126 to flash substantially continuously.
In the event that the distance between the subject vehicle and the second vehicle continues to decrease below a third predetermined distance such that the control unit 114 determines that a collision between the two vehicles may be imminent, it communicates again with the BCU 124 which generates a third alert signal, for example by causing the vehicle horn 128 or the sounder of the vehicle anti-theft alarm (not shown) to be activated.
This succession of alerts, which are visible and/or audible by the driver of the second vehicle, is intended to warn the driver that the second vehicle is in close proximity to the subject vehicle and that the driver should stop the second vehicle or change direction if a collision is to be avoided.
In contrast with existing vehicle parking systems, therefore, the system of the invention is able to alert the driver of a second vehicle that the second vehicle is approaching dangerously close to the subject vehicle, even if the subject vehicle is unattended and with its ignition switched off.
It will be understood that the above description is given by way of example and that, consequently, there are a number of variations that could be implemented.
For example, the transducers 112 need not be acoustic or ultrasonic transducers. Instead, electromagnetic transducers for transmitting and receiving milliwave, microwave or other electromagnetic radiation could be employed. It is envisaged that the use of electromagnetic signals may advantageously improve sensitivity, resolution and accuracy.
The transducers may be provided only at the rear of the subject vehicle. Alternatively, transducers may be mounted in both the front and rear bumpers of the vehicle and, optionally, even along the sides of the vehicle.
The described system is operational in the second, collision avoidance mode only when the vehicle ignition is switched off, remaining in a quiescent state until the proximity sensor 122 detects movement of an object near the subject vehicle, at which point the system becomes active. The system may also be operational when the vehicle ignition is on, although in this instance, the control unit 114 may be connected to receive a signal from the vehicle's speed sensor (not shown) and arranged to be activated only when the speed of the
vehicle is zero or approaching zero. Additionally or alternatively means, such as a switch, may be provided to permit the driver to manually activate the system so that it remains quiescent whilst the vehicle is driving in, for example, very slow moving, closely spaced traffic.
The provision of a proximity sensor 122 to activate the system reduces the continuous current drain on the vehicle battery since such sensors operate at lower current levels than the transducers 112. This is particularly beneficial as the system is intended for maximum use when the vehicle is unattended with the engine switched off.
However, the use of is not essential and may be avoided by, for example, providing the driver with a switch to activate the system manually or by arranging the system so that it is activated at all times whilst the vehicle ignition is switched off. In this case, owing to the magnitude of the current that the system may require whilst continuously transmitting and receiving the ultrasonic or electromagnetic signals, it may be desirable to provide means, such as a solar panel, for recharging the battery whilst the ignition is off.
In any event, means may be provided for ensuring that the system is deactivated before the remaining charge on the vehicle battery is drained to a level which would prevent the vehicle from being started.
In the described embodiment, the system generates three different alert signals in response to the distance between the subject vehicle and the second vehicle decreasing below three predetermined threshold distances. It will be appreciated, however, that greater or fewer threshold distances may be defined.
In addition, the alert signals, which are generated in response to the second vehicle moving closer, can be selected and/or varied as desired. For example, the hazard warning lamps may be arranged to flash at an increasing rate as the
distance between the two vehicles decreases until, when the second vehicle has approached to within a final critical distance, the hazard lamps may be πiuminated continuously and the horn may additionally be activated.
In order to prevent the system from being activated in inappropriate conditions, for example whilst the subject vehicle is parked along a street where passing vehicles are in close proximity to the vehicle, the system may be arranged to determine the speed or rate of closure of the second vehicle. This may be achieved by measuring the Doppler shift in frequency of the reflected signal compared with the transmitted signal, in conventional manner
A similar effect may be achieved by differentiating the measured distance between the two vehicles with respect to time or through a similar or equivalent calculation. For example, the control unit may be arranged to compare the measured distance dj between the vehicles at, say, time ti with the measured distance d2 at time t2 and then estimate the rate of closure R of the second vehicle with respect to the first vehicle by calculating R = (dx - d2) / (t2 - ti).
The activation of the system and/or the generation of the alert signals may then be made dependent on the calculated rate of closure of the second vehicle. For example, if the rate of closure of the second vehicle is above a first predetermined level, for example 40km/h, then the system may assume that the second vehicle is merely driving past and is not intending to park adjacent the first vehicle. The system thus remains in its quiescent state.
On the other hand, if the rate of closure of the second vehicle is below the first predetermined level but greater than a second predetermined level, for example 20km/h, then the system may automatically generate the most severe alert signal (such as flashing lights and continuously sounding horn) when the second vehicle approaches within the first predetermined threshold distance.
Alternatively, where a Global Positioning System (GPS) or similar function is provided on the vehicle for determining the position of the vehicle, the control unit 114 may be arranged to receive a position signal from the GPS system and to activate the system of the invention only if it determines that the subject vehicle is parked or is stationary in a location where other vehicles may park in close proximity. Thus, if the control unit 114 determines from the position signal that the subject vehicle is stationary, for example, at the side of a main road or on the hard shoulder of a motorway, it does not cause the system to be activated. The control unit may determine whether or not the system should be activated using a fuzzy logic algorithm.
Where the alert signals take the form of the illumination of one or more of the vehicle lamps and/or the operation of the horn, it is not essential that these be controlled by the vehicle's BCU 124. If the subject vehicle is not provided with a BCU 124, it will be clear to the skilled person that the control unit 114 may itself be connected to the circuits for the vehicle lights and horn in order to activate and drive them directly.
The present invention provides a simple and effective system, which can be provided as a relatively inexpensive modification or addition to an existing parking system for a vehicle, which alerts the driver of a second vehicle that the distance between the vehicles has reduced below a safe level and that a collision may occur. This may reduce the likelihood of damage not only to the subject vehicle but also to adjacent vehicles, particularly where such vehicles do not have a parking system fitted.