Patent Application
20070038361
Traffic congestion has been a problem since the day of the chariot. In more modem times, various attempts have been made to relieve traffic congestion. For example, traffic volume control stoplights have been used to provide for timed entry of vehicles onto highways. The stoplights are activated when the density of traffic flow exceeds a certain number of vehicles per hour. Additionally, multiple passenger restricted lanes have been tried as well as reversible “express lanes” to provide more traffic lanes for inbound rush hour vehicles in the morning and outbound vehicles in the afternoon. Despite all of these attempts, traffic congestion has increased dramatically over the past two decades. In the 13 largest US cities, drivers spend the equivalent of eight workdays each year stuck in traffic. According to the US Transportation Department, America loses billions of dollars a year due to freight bottlenecks and delayed deliveries, and consumers lose billions of dollars worth of fuel consumed each year while stuck in traffic jams.
Studies have shown that one of the biggest obstacles to optimal traffic flow is the driver. If drivers were not involved in applying the accelerator and/or the brakes, they would not be able to over react or under react to traffic conditions. The over reactions and under reactions result in “standing wave” traffic patterns and substantial increases in the amount of wasted fuel and general traffic congestion.
When a certain density of traffic is reached, a standing wave or slinky type pattern occurs on the highway even in the absence of any outside conditions such as construction, inclement weather, accidents or police action distractions. The standing wave pattern is characterized by the same number of vehicles per square meter moving at a substantial velocity at one moment and coming to a stop or near stop a few moments later. The traffic expands and contracts because of a human visual defect discovered by the present inventors that renders it impossible for vehicle operators to judge the rate of acceleration or deceleration of the vehicle ahead. A typical scenario occurs when there are enough cars on the highway to prevent easy lane changes. At this point, each driver must react to his or her perception of the speed of the vehicle ahead. Once any driver in a full lane applies the brakes, even if the vehicle is not slowing substantially, a chain of events is initiated that often leads to stopped traffic. The inability of the human visual system to accurately gauge rates of deceleration causes drivers to overcompensate so that each subsequent car in a highway lane slows more than is required until the traffic in that lane has stopped. As the traffic in the lane begins to move again, drivers cannot accurately gauge the rates of acceleration of the cars ahead of them so they do not speed up as fast as they could. Accordingly, the unwinding of the traffic jam is slower than expected as well. Traffic continues to expand slower than it should and to contract faster than it should such that the same number of cars per square meter are moving at a substantial rate one moment and at a stop or near stop a few moments later.
In general, the present invention provides a system and a methodology for facilitating the flow of traffic along a highway. The system and methodology enable a vehicle to maintain a more equal speed with the preceding vehicle to create an efficient and smooth flow of traffic. The smoother traffic flow results in improved fuel consumption and reduced emissions. The technique utilizes a sensor system and a simple indicator to aid the driver of a vehicle in determining whether the distance to the preceding car is increasing or decreasing, prompting the driver as to the appropriate time to begin braking or accelerating. The braking may not coincide with the first sign of brake lights showing on the vehicle ahead.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present invention relates to a system and methodology for reducing traffic congestion, improving traffic flow, and saving fuel during motor vehicle use. Simple indicators are provided to a driver of a vehicle in an unobtrusive form to help the driver determine whether the immediately preceding vehicle is moving away from the driver's vehicle, e.g. positively accelerating relative to the driver's vehicle, or moving toward the driver's vehicle, e.g. negatively accelerating (decelerating) relative to the driver's vehicle. In one embodiment, the indicators comprise lights that are located within a vehicle such that they are noticeable in the peripheral vision of the driver without intruding on the driver's observance of the road. The present system and methodology are designed to provide the indicators with respect to the vehicle immediately ahead of and in the same lane as the vehicle of the operator. In some embodiments, the system functions with respect to the preceding vehicle only when that vehicle is within a relatively small forward region, such as between 3 and 60 feet in distance ahead of the vehicle of the operator.
The system also is designed to be relatively inexpensive to enable retrofitting of existing cars and addition as original equipment without substantially adding to the cost of the vehicle. The greater the number of vehicles on a given highway utilizing the present system and technology, the greater the potential for avoiding standing wave traffic patterns and for facilitating the smooth flow of traffic.
Referring generally to
The sensor system 32 is designed to detect and measure an energy signal 34 received from the lead vehicle 26. By detecting and processing data from the energy signal, a determination can be made as to whether the speed of the lead vehicle 26 relative to vehicle 28 is positive or negative. Depending on the specific embodiment, the energy signal 34 can be initiated at lead vehicle 26, or it can be initiated in following vehicle 28 and reflected from vehicle 26. By way of example, the energy signal 34 may comprise a microwave signal, such as that used in a Doppler radar system, a Bluetooth™ signal, an FM signal, a radio frequency identification (RFID) signal, an infrared signal, a laser light signal or other appropriate electromagnetic energy signals. In some applications, the energy signal 34 is designed to be useful within a limited region or envelope 36 to avoid interference with vehicles in other lanes or vehicles farther ahead or behind the subject vehicle 28. In one example, the region 36 is limited to an envelope that extends forward less than approximately 60 feet in distance and that covers a lateral range narrower than the highway lane 22. However, other sized regions 36 can be implemented.
The energy signal 34 is received by an appropriate sensor 38 of sensor system 32, and the data is processed by an appropriate processor 40, such as a programmable microprocessor, to determine whether the distance between vehicle 26 and vehicle 28 is increasing or decreasing, e.g. whether the relative speed is positive or negative. If an increase or decrease is determined, this information is provided to the driver of vehicle 28 through a simple indicator mechanism 42 located in the peripheral vision of the driver, as illustrated in
Depending on the specific application, sensor system 32 also may comprise a reflected energy transmitter 56 used to output energy signal 34 which is reflected back from the immediately preceding vehicle to sensor 38. As illustrated, reflected energy transmitter 56 also can be mounted to steering wheel 52. Alternatively, the energy transmitter 56 can be mounted to the vehicle in a variety of other locations.
One embodiment utilizing reflected energy transmitter 56 is a radar system that includes an antenna 58 (see
As long as vehicle 26 is moving away from vehicle 28, first indicator 44 is active. For example, if first indicator 44 comprises a light, such as a green LED, the indicator is illuminated to make the operator of vehicle 28 aware that the lead vehicle 26 is increasing the distance therebetween. This indicator is visible in the driver's peripheral vision and tells the driver it is safe to increase acceleration. When the Doppler effect shows that the distance is decreasing between vehicle 28 and lead vehicle 26, second indicator 46 becomes active. For example, if second indicator 46 comprises a light, such as a red LED, the second indicator is illuminated to make the operator of vehicle 28 aware that the distance between it and the lead vehicle 26 is decreasing. Indicator mechanism 42 also may comprise a mechanism for indicating a match in speed between vehicles 26 and 28 where neither acceleration nor breaking is required by the driver, allowing for the occurrence of fuel-saving coasting. For example, indicators 44 and/or 46 can be illuminated with a different color, e.g. illuminated with a yellow LED, or an additional indicator can be incorporated into indicator mechanism 42.
In the radar/Doppler system described, the strength of a radar return signal or echo is inversely proportional to the fourth power of the distance of the target from the antenna 58, assuming targets of the same reflected area. Accordingly, a target, e.g. an automobile, positioned half the distance from the antenna as another target of the same character (size, mass, reflectivity) returns a signal 16 times stronger than the more distant target. In this embodiment of system 24, the system can be configured to “see” only the closest target vehicle, i.e. the vehicle directly ahead of vehicle 28, by sensing only the strongest echo. Even if the target vehicle ahead is a small car with a reflectivity and thus a signal strength of only 10% that of a truck positioned ahead of the small car, the Doppler radar system is able to recognize the stronger signal from the true target vehicle directly ahead due to its proximity. This is especially true in heavy, slow traffic where traffic flow system 24 is of particular benefit. The illustrated system also does not require additional expensive circuitry to subtract the speed of the driver's vehicle from closing speeds of other vehicles, because actual speeds of the other vehicles are not relevant to providing a simple indication of differential speeds between the driver's vehicle and the immediately preceding vehicle traveling in the same lane 22.
In this particular embodiment, system 24 can be designed to block or ignore energy signals received from objects in certain situations. For example, signals received from vehicles moving through curves in adjacent lanes can be ignored. Additionally, signals from vehicles in oncoming lanes as well as vehicles or other objects, e.g. road signs, along the side of the road can be ignored. Blocking circuitry can be used to place limitations on the angle of the transmitted and received signals, as known to those of ordinary skill in the art. The use of blocking circuitry may depend on the actual type of energy signal 34 employed in system 24. Some examples of energy signals that produce very narrow and compact waveforms include microwave signals, single or multiple band FM signals, light emitting diodes, laser signals, lidar signals and certain other forms of energy signals.
In another specific embodiment, reflected energy transmitter 56 comprises an infrared LED or laser diode, and sensor 38 comprises an infrared or laser energy signal detector, as illustrated in
In
The processor 40 utilizes software that performs a phase locked loop function and controls variable delay 78 to maintain any incoming wavefront edge centered within a sample window. The amount of delay represents distance 66 to the next vehicle, e.g. vehicle 26. In this embodiment, the functional concept depends on measuring any change in the round-trip propagation time from energy transmitter 56 forward to vehicle 26 and then back to sensor/detector 38. Detecting a change as coarse as 1 foot is adequate to provide appropriate indications to a vehicle driver. In this example, sensor system 32 should be able to detect a difference of about 1 ns in the round-trip propagation travel time for the energy signal 34.
Referring again to
Accordingly, as the distance between vehicles 26 and 28 closes, the waveform edge shifts from the center sample to earlier samples (closer to detector/sensor 38), and the software adjusts the delay to bring the edge back to the center of the sample window group. When this occurs, the programmed processor 40 is able to realize the distance between vehicles is decreasing and to output an appropriate control signal to indicator mechanism 42. As the distance between vehicles increases, the opposite occurs and the software on processor 40 reduces the delay to keep the waveform edge in the center of the sample window. When this occurs, processor 40 is able to realize the distance between vehicles is increasing and to output an appropriate control signal to indicator mechanism 42. Specifically, appropriate software filters the result to avoid flashing of indicators 44, 46 and then appropriately illuminates the proper indicator 44 or 46. Of course, in other embodiments, indicators 44 and 46 may be designed to provide other types of visual, audio or other simple indicators to facilitate improved driver response.
In the example illustrated, variable delay 78 is designed with a very fine resolution, e.g. less than 100 ps, of control by processor 40. The windows sampler 72 also has very fine time steps between each adjacent sample, e.g. less than 100 ps per step. The signal emitter and sensor/detector must be designed to have adequate signal strength for reliable loop operation. In one example, transmitter 56 comprises a laser diode emitter, but other forms of energy can also be used, such as Doppler microwave radar, infrared, radio frequency identification, ultrasound, and other energy forms. Furthermore, appropriate waveform modulation and encoding allow the software on processor 40 to ignore noise from other objects and to determine how many waveform pulses are in “flight” between the energy transmitter 56 and the detector 38 for approximate distance measurement. By way of example, in many applications, a maximum length polynomial generator code of eight bits or more clocked by the system clock is adequate.
In an alternate embodiment, traffic flow system 24 can be incorporated into a larger number of vehicles such that the system can be used to send information on relative velocity between sequential vehicles to vehicles that are farther back. In this embodiment, a communications chain is formed using each vehicle to receive the information from the car in front of it and to send it back to the next sequential vehicle. The system component in each vehicle can use a filtering algorithm, such as a matched filter approach, to combine its own measured information with information passed back from the forward vehicle. This combined data can be transmitted back to the next sequential vehicle. This approach allows a tailored warning time and acts like a “feed-forward” filter network. The use of combined data from multiple sequential vehicles can facilitate improved network stabilization, i.e. improved traffic flow.
To implement this alternate approach, the warning information must arrive earlier than the response time of the driver to increase overall stability of the traffic flow system. The stability is increased by allowing a controlled limited response to this situation instead of the usual over braking and over accelerating that occurs in congested traffic. By way of example, the data transfer function from vehicle to vehicle can be achieved by the analysis of a discrete time model of a transmission line with interleaved gain blocks to achieve stable control loop operation. This can be implemented by constructing energy transmitter 56 with a second emitter and by enabling detector 38 through the use of orthogonal PN codes to modulate the two emitters. The software on processor 40 can then receive the overlapping code pair of its own emitter reflected along with the received signal from the emitter in the vehicle ahead. The processor 40 is readily programmed to mathematically demodulate the two signals into their own data patterns.
In another embodiment, the energy signal 34 is not reflected from the forward vehicle but is emitted from the forward vehicle for receipt by detector 38 in the following vehicle 28. Referring generally to
The GPS data output by transmitter 56 is received by sensor system 32 of the following vehicle 28. The sensor system 32 of vehicle 28 is operatively coupled with a GPS unit 84 which obtains GPS data related to the geographical location of vehicle 28 on a continuous basis. With the aid of processor 40, sensor system 32 is able to continuously compare the location of lead vehicle 26 with its own geographical location and to determine any changes in position between the vehicles resulting from an increase or decrease in the distance between the vehicles. If such changes in relative position are detected, sensor system 32 outputs the appropriate control signal to indicator mechanism 42, as described above. This type of GPS based system also enables a given vehicle, such as vehicle 28, to track changes in the positions of numerous vehicles around vehicle 28. Thus, the GPS based system can readily be used to provide the driver of the vehicle with simple inputs related to the immediately preceding vehicle or other vehicles that would aid the driver in facilitating an improved traffic flow pattern. The GPS based embodiment of system 24 also can be programmed to ignore RFID signals or other transmitted signals from specific vehicles, such as vehicles moving in opposite directions or vehicles located behind vehicle 28.
By incorporating vehicle flow control system 24 into numerous vehicles, the traffic flow patterns of those vehicles along a given highway can be improved dramatically. The flow control system 24 can be incorporated into new vehicles as original equipment or can be retrofitted into existing vehicles. In fact, the components of system 24 can be constructed in a modular form enabling transfer of the system from one vehicle to another.
In operation, each vehicle on a given highway obtains an appropriate energy signal from a vehicle immediately ahead, as illustrated by block 86 of
The flow control system 24 enhances a driver's ability to analyze movement of vehicles in a manner that facilitates a smoother flow of traffic, particularly in congested traffic situations. As greater numbers of vehicles implement the flow control system 24 the traffic flow patterns continue to improve. A variety of components, software and procedures can be used to implement this approach of providing simple indicators to operators of vehicles that improve their responses in congested traffic. For example, the system can integrate feedback from multiple cars with respect to their GPS location and instruct a slow lead car with no vehicle ahead of it to change lanes to the right to improve overall traffic speed in a given line. The improved responses facilitate the smooth flow of traffic by avoiding or reducing standing wave patterns, for example. In some embodiments, flow control system 24 is designed to be active only when the vehicle is traveling at a relatively slow speed, e.g. below 40 mph, which is typical in heavy traffic flow patterns.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.
The present document is based on and claims priority to U.S. provisional application Ser. No. 60/706,675, filed Aug. 10, 2005.
| Number | Date | Country | |
|---|---|---|---|
| 60706675 | Aug 2005 | US |
