Patent Application
20110196580
The present invention relates to a traffic system, and relates particularly to a system and method for indicting wireless traffic information.
Traditional traffic information indicting system and device are mainly traffic signal lights (“traffic lights” in short) and traffic indicating signs (“road signs” in short), which provide information including traffic indicating information, road indicating information, destination information, road condition ahead information, weather prompting information, or other traffic management information.
The world's first traffic indication having the red, amber and green lights was formally born in New York, U.S.A. in 1918. It has a ninety year history since nowadays. The appearance of the three-color traffic indicating lights brought revolutionary changes to city traffic. Its control system also develops from electric control from the 50s to nowadays' electronic and computer intelligent control. It brings city traffic towards maturity.
However, the existing traffic indicating system, including theses red, amber and green lights and the regular road signs, all along has a disadvantage which remains unsolved, i.e. all indications rely on the sense of sight. The effect is obviously unsatisfactory especially under bad weather conditions (e.g. heavy rain or dense fog), or for drivers who are suffering from color blindness or color-deficiency. Also on highway, relying on the sense of sight can create problem especially in dense fog weather condition when multi-vehicle collision often occurs. As far as car accident is concerned, it has in fact become the first killer of mankind. Over the past 100 years, 40 million people died in car accidents around the world. This number exceeds the number of casualty during the Second World War. Since the entry of the 21st century, there are approximately 600,000 people died in car accidents each year around the world. Hence, people consider car accidents as the war on the road.
Apart from reliance of the sense of sight that is associated with traffic accidents, the reaction and the operation of a driver are also essential factors. Vehicles travel on highways very fast. When accident suddenly occurs in bad weather condition, people's reaction is usually not fast enough. This is a reason why there are multi-vehicle collisions on highways so often. Apart from keeping an appropriate speed and distance, it is also important to pay attention to the relative speed between vehicles. To achieve safe driving, a driver needs to take immediate reaction when it is discovered that the relative speed with the vehicle ahead has changed rapidly, and at the same time transmits relevant information to the vehicles behind so that all vehicles can take immediate action to effectively avoid the occurrence of tragic. According to statistics, if a driver is given half a second of advanced reaction time, it can reduce 30% of rear-ending incidents and 50% road-related incidents. Therefore, having an effective vehicle warning system is very important in driving safety.
It is necessary to have a dynamic distance detecting device to realize the warning of vehicle collision. Nowadays, the existing technology mainly involves laser and radar (microwave). The device adopting this technology can transmit laser or microwave signals when vehicles are in motion. Then, distance measuring (measure the time difference or shift of frequency of the transmitting/receiving signals) can be carried out according to the echo reflecting from the vehicle in front. When hazardous condition occurs, hazard prompting or automatic braking can be performed to avoid collision with the vehicle in front. The main disadvantage of this kind of system is that the technology is relatively complicated and that interference can easily occur. The driving condition on a road is very complicated. When the number and density of vehicles are getting higher, or when speeding, turning, or special signs or advertisements appear along the roadside, the reflected waveforms can sometimes be difficult to predict. This would lead to false alarm or wrong operation. Also, since this kind of system cannot detect the existing traffic signal system and cannot carry out information exchange with other vehicles, it has no way to prevent vehicles from running the red light or prevent collision with other vehicles. Furthermore, laser and radar can generate electrical pollution to the environment. The reason is that when similar devices are installed in a number of vehicles in the same environment, it is difficult to avoid interference among one another. Finally, this kind of technology is relatively high in cost. It is difficult to apply this to all vehicles in a popular manner.
The technical problem needed to be solved by the present invention is to provide wireless traffic information indicating method and system in light of the deficiency in the above-mentioned existing technology. This wireless traffic information indicating method and system are wireless, dynamic, real time and all-weather operable. It does not rely on the sense of sight of a human being. It does not even rely on the reaction of a human being. It can automatically carry out emergency state operation in order to eliminate possible occurrence of a hazardous situation. Also, it can timely transmit related hazard information to vehicles behind so as to avoid occurrence of multi-vehicle collision incidents.
To solve the above-mentioned technical problem, the present invention provides a wireless traffic information indicating method including the following steps:
a first vehicle or a front object synchronously and directionally transmits a first wireless signal for time synchronization and a second wireless signal for distance measurement; and
a second vehicle directionally receives the first wireless signal and the second wireless signal, and calculates the distance between the second vehicle and the first vehicle or the front object based on the first wireless signal and the second wireless signal.
The present invention also provides a wireless traffic information indicating system including:
wireless transmitting device installed in a traffic signal light or a traffic road sign or a vehicle traveling in front for directionally transmitting digital coded first wireless signal and second wireless signal having different speeds of transmission;
wireless receiving device installed in a traveling vehicle for directionally receiving the first wireless signal and the second wireless signal, interpreting coded information in the received first wireless signal and second wireless signal, and calculating the distance between the traveling vehicle and the traffic light or the traffic road sign or the vehicle traveling in front based on phase time difference of the received first wireless signal and second wireless signal.
The present invention may have the following advantageous effects: (1) it is a system that does not rely on weather condition and sense of sight (2) it can operate in all-weather condition; (3) it can display information on traffic light signal and provide information on the countdown of change of traffic light signal; (4) it has the function of preventing red-light-running; (5) it can display the distance from and the relative speed of the vehicle in front; (6) it can automatically control the traveling condition of a vehicle in case of emergency; (7) it can transmit related information such as traffic light signal and hazard signal to the vehicles behind; (8) it can display/prompt other road traffic information; (9) it is an environmental-friendly, electronic pollution free signal system; and (10) it is low in cost and easy for popularized application.
In summary, the implementation of the present invention can effectively increase the performance of the road traffic and can have a better protection of drivers' safety.
Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings wherein:
The present invention will now be described with reference to the accompanying drawings.
The key of the present invention to achieve the all-weather dynamic traffic information reception and indication is the adoption of wireless signal having the function of all-weather directional operation in order to carry out the transmission of information. The transmission capacity of infrared (especially infrared having 8-14 mm wavelength) and ultrasound (especially ultrasound having about 20 kHz) in atmosphere is very strong. It almost won't be affected by the interference of light, dense fog, dust, rain, blowing snow and electromagnet in the air. These two kinds of signal can be more adaptable to bad weather condition than the sense of sight of a human being. They would not be affected even in night time. It is the key to the realization of all-weather operation. Also, wireless signal that can realize directional signal transmission may also include microwave and laser, etc. Therefore, the present invention does not exclude the use of microwave and laser, etc for the transmission of signal. The present invention uses infrared and ultrasound as the most preferred (preferred) signal source because these two kinds of signal source are currently the cheapest and safest signals. They would not cause harm to human body and the sight. Also, they would not cause electromagnetic wave pollution in the air. They are green environmental-friendly signal sources.
The reason for transmitting the two sets of wireless signal at the same time in the present invention is that a vehicle can calculate the distance and the speed between the vehicle and the traffic light based on the two sets of wireless signal so as to draw the attention of the driver when necessary. The speeds of transmission of these two kinds of wireless signal in the air are different. Infrared signal transmits in light speed (300,000 km per second). Therefore, it is not necessary to consider its delay in transmission. The rate of transmission of ultrasound signal in the air is 340 m per second (at 15° C.). This speed is relatively slow as compared to the speed of infrared. Hence, the wireless receiving device 17 can determine the distance between the vehicle and the traffic light (in reality the wireless signal can modulate the distance between the vehicle and the vehicle's stop line) based on the time difference (because the wireless signal will be coded and modulated, therefore this time difference is also called phase time difference or phase difference) in receiving of these two different wireless signals. The calculation is: S=V*ΔT, where S is the distance between the receiver and the emitter, V is the transmission speed of ultrasound in air, ΔT is the phase time difference of infrared and ultrasound.
Since the present invention can calculate the real time distance between the transmitting device and the receiving device, it also has the function of measuring the speed of vehicle in motion. It can calculate the real time speed of a vehicle by continuously measuring the distance from a fixed transmitting sign (e.g. the above-mentioned signal light). This can prompt or adjust the driving condition of vehicles. To realize this function, the system may further include a red-light-running preventing device 19. The device 19 is actually a device for controlling the traveling of a vehicle. It can provide necessary prompting to a driver according to the vehicle speed and the distance from the stop line at the red light. It can also automatically apply the brake such that a vehicle can stop safely before the stop line at the red light.
In reality, the position and the number of transmitting and receiving devices can be determined by the construction of a vehicle as well as the angle, the sensitivity and coverage of the signal transmission/reception of the vehicle. This allows the vehicle to have transmission function at the back, the left and right sides at the back of the vehicle. In a vehicle braking condition, hazardous condition, turn left and right condition, wireless signals can be transmitted towards a correct direction. The wireless signal can include wireless coded signals of the above-mentioned conditions, have an appropriate coverage, and can be able to receive signal from the front, the left and right sides at the front of the vehicle.
We also called this time difference a phase difference or a phase time difference. In the figure, T1 and T2 show the phase time differences of the two signals. T3 also shows the phase time difference of the two signals only that the measuring position is not the same. Signal can apply different coding methods. The most common one is the use of “0” and “1” digital code defined by the length of time and the level of the signal pulse. As shown in the figure, a pulse with a relative narrow space represents the digit “0”, and a pulse with a relative wide space represents the digit “1”. In practice, there can be other different methods of coding and ways of defining the digits. To determine whether two waveforms (date packages) are data transmitted in the same period of time, the above-mentioned waveforms may further include recognition code (ID). The ID of the front wave is 0110 and the ID of the rear wave is 0111. The system can only carry out comparison between waveforms having the same (or corresponding) ID. This can avoid the situation where waveforms are dislocated. This can realize synchronization of signals in the receiving device.
Calculation and analysis are carried out below using actual data as an example. Assume the above-mentioned waveforms come from the system in
The driving control device 28 in
For vehicles that are traveling slowly or have already stopped (e.g. waiting for traffic signal at intersection) or the speed of the vehicle in front is not less than the speed of the vehicle behind, and in a forward accelerating condition (e.g. in
The system of the present invention may further include electronic road signs displaying/indicating functions. These electronic road signs displaying/indicating function can be seen in
Road sign and traffic light information come from the road signs and traffic lights provided on the road. They can be called wireless electronic road signs and wireless electronic traffic light devices. Compared to the traditional road sign and traffic light, the biggest advantage of the electronic road sign and traffic light system is that it is an all-weather signal system. No matter what is the weather condition, the system can properly receive and display/prompt the related information so as to make driving convenient and safe. Also, the system can display other additional information, e.g. the countdown of change of traffic light so that a driver can slow down before traffic light changes to red, and get ready before traffic light changes to green in order to increase the road traffic efficiency. Furthermore, the system can display speed limit, road block information, slowdown information, pedestrian path information, road condition ahead information, weather information and other traffic management information, etc.
It is necessary to note that sometimes it is required to make necessary compensation/correction of the distance data calculated by the system of the present invention in order to satisfy its requirement on accuracy. There are mainly two aspects with regard to compensation/correction. One aspect is the effect of temperature on the speed of transmission of ultrasound. According to experiments, transmission speed of ultrasound in air and temperature have the following correlation, wherein the temperature unit is ° C. and the ultrasound speed unit is m/sec.
Another aspect on correction is the effect of the angle of transmission of wireless signal.
Therefore, it is necessary to use triangle side length formula (Pythagorean theorem: S2=H2+D2) to correct the linear distance S obtained from the receiving device. To achieve the correction, the wireless digital coded information received by the receiving device should include information on the height H.
In the above embodiment, the repeat transmission (retransmit) issue in wireless signal has not been mentioned. In fact, this issue is also very important. For example, in the hazardous condition mentioned hereinbefore, emergency brake can be applied by the driving control device 28 to eliminate possible occurrence of a vehicle collision incident. However, it is a very dangerous operation itself to suddenly apply a brake on a highway because vehicles behind would face the same collision problem. If it is not handled properly, multi-vehicle collision incident may occur. To solve this problem, it is necessary to let the vehicles behind know what is happening in front and take the same measure in applying the brake in order to effectively avoid multi-vehicle collision. A repeat transmission function is therefore necessary.
The relay device 91 directly receives wireless signal from the wireless transmitting device on the electronic traffic light 90 through the air. Apart from air, the transmission can be carried out by a special electric cable 95 or other wireless channel (“third signal channel” in short). In this situation, the relay device 91 may adopt a metallic structure with a portion being buried below the stop line. It only requires an exposed transmitting head to perform signal transmission. One advantage of this method is that it can avoid the blockage of signal when pedestrians are crossing the road or other vehicles are traveling across the road. Also, since the relay device 91 is directly facing the vehicles on the road, the effect of its transmission and reception is most ideal. This kind of wireless transmitting device buried under the stop line can also transmit information including travel direction of special vehicle lanes, and information on destination and speed limit. The relay device 91 in the embodiment of the present invention may have the function of restoring a signal. It can restore the original infrared signal and ultrasound signal based on the signal of the third channel. Also, it can make the phase between the two signals same as or corresponds to the phase of the original signal at the relay point, or restore the coded information of infrared and ultrasound and carry out relay transmission based on a single infrared or ultrasound coded information.
Infrared coded signal 107 and the ultrasound coded signal 108 transmitted from the wireless transmitting device 101 can be received by a wireless receiving device 112 installed on a traveling vehicle 110. The wireless receiving device 112 may include an infrared receiver and an ultrasound receiver corresponding to the wireless transmitting device 101, and associated decoding and data package synchronizing units for detecting the received data package ID, comparing the infrared coded signal and ultrasound coded signal having the same or associated ID in order to calculate the linear distance between the wireless transmitting device 101 and the wireless receiving device 112. The information received by the wireless receiving device 112 can be displayed and prompted by information displaying device and audio prompting device. In order to effectively analyze the calculated data, a safe driving system 111 in the vehicle may further include a sensor inputting device for providing data such as speed and accelerator. This can allow a driving control device to control the accelerator and the brake system when the safe driving system 111 discovers an occurrence of a hazardous condition (e.g. speed of a vehicle is too fast, distance between vehicles is too close, vehicle in front applies brake suddenly, etc.). The safe driving system 111 may further include information on the height of installation of the wireless transmitting device 101 and other preset information so as to compensate and correct the received data. Regarding data of temperature compensation, one can adopt the temperature value measured in the present vehicle, or adopt the temperature information included in the information received from the transmitting device in front.
The traveling vehicle 110 may further includes a wireless transmitting device 116. The wireless transmitting device 116 may include an infrared emitter and an ultrasound emitter, and associated code controller and data package ID unit for transmitting infrared coded signal 118 and ultrasound coded signal 119. The wireless transmitting device 116 can be connected to a vehicle driving condition information unit 115, other associated information unit 117 and the above-mentioned safe driving system 111. Based on the information of the safe driving system 111, the vehicle driving condition information unit 115 and the associated information unit 117, the wireless transmitting device 116 can determine whether to transmit infrared coded signal 118 and ultrasound coded signal 119, and can determine the coded information included in the information to be transmitted. The information may include traveling condition of the present vehicle such as emergency brake, hazard signal and turning signal. Furthermore, it may include information such as speed and acceleration of the vehicle so that the vehicle behind can be prompted to carry out related safe driving operation based on the received information. Besides, the wireless transmitting device 116 can also be used as a relay device for retransmitting digital coded information transmitted from the electronic traffic light or the electronic road sign device 100, and received by the safe driving system 111. Depending on the actual situation and requirement, the retransmitted signal can have its code and phase kept as those that are received, or they can be changed or added to the information and phase of the present vehicle.
In step S1101, a first vehicle or a front object synchronously and directionally transmits a first wireless digital coded signal for time synchronism and a second wireless digital coded signal for distance measurement. The first wireless signal and the second wireless signal are digital coded.
In step S1102, a second vehicle directionally receives the first wireless digital coded signal and the second wireless digital coded signal. In the present invention, the first wireless signal is preferably an infrared signal and the second wireless signal is preferably an ultrasound signal.
In step S1103, the second vehicle processes the received signals, finds out the data packages having the same data package ID in the first wireless signal and the second wireless signal, and measures the phase time difference between the two signals.
In step S1104, based on the above measured phase time difference of the first wireless signal and the second wireless signal, the second vehicle calculates the distance between the second vehicle and the first vehicle, or the distance between the second vehicle and the front object.
In step S1105, the second vehicle carries out compensation and data correction based on the air temperature and effect on the speed of transmission of wireless signal in the air that corresponds to the said temperature at the time when the first wireless signal and the second wireless signal are received.
In step S1106, the second vehicle carries out decoding of the coded information included in the received wireless signals, and restores the original digital information in order to realize the transmission of the related information.
In step S1107, the second vehicle obtains information on the height of installation of the transmitting device from the restored digital information, and corrects the above-mentioned distance parameter based on the height information.
In step S1108, the second vehicle continues to detect and obtains the above-mentioned compensated and corrected distance parameter, and calculates the relative speed and acceleration of the two vehicles from the change of time and distance.
In step S1109, the second vehicle retransmits the received first wireless signal and the second wireless signal according to situation and need, processes the original first wireless signal and the second wireless signal so that they include corresponding information of the second vehicle.
In all of the above-mentioned embodiments, it has been described that basically the infrared signal and the ultrasound signal are simultaneously transmitted and received. In the actual system, if it is not necessary to measure the distance, then it only requires the transmission of one kind of wireless coded signal. Therefore transmission of a single wireless signal can be seen as a special embodiment of the system. For example, infrared or ultrasound digital coded signal can be adopted to directionally transmit traffic signal light and traffic road sign information in order to realize all-weather traffic information indication. It can also be used to transmit to the vehicle behind information on the vehicle's travel condition, such as emergency brake, hazard, turning, speed and acceleration, etc. so that the vehicle behind can obtain related prompting in order to avoid collision and realize driving safety. For adopting ultrasound signal having a fixed frequency, the vehicle receiving the signal can calculate the relative speed between the emitter and the receiver based on the change of its frequency using Doppler effect. The idea and principle of the present invention are applicable whether one kind or two kinds of signal transmission are adopted.
Regarding the issue of transmitting distance of infrared and ultrasound of the present invention, it relates to factors such as the angle of transmission of signal from the emitter, the power of transmission of signal, etc. It also relates to signal frequency/wavelength and signal coding format. Generally speaking, the infrared carrier wave signal having 8-14 mm wavelength can achieve signal transmission of over 1000 m in absence of a relay device. In the system of the present invention, the adoption of a 200 m transmission distance is already sufficient. For ultrasound signal, its transmission distance is usually shorter than that of infrared signal. Nowadays, the distance range of the most commonly used 40 kHz frequency rangefinder is usually around 15 m. According to the characteristics of absorption rate and attenuation which is proportional to the square of frequency, the absorption rate of ultrasound having frequency of 40 kHz is about 4 dB/m. The absorption rate of ultrasound having frequency of 20 kHz is only about 1 dB/m. Hence, in 20 kHz the distance range of ultrasound can be increased to about 60 m.
Since the present invention adopts a direct signal receiving method that is different from an echo receiving method of a rangefinder, its distance range is more than 2 times longer than that of a rangefinder, i.e. a linear distance of about 120 m. This is sufficient for the system of the present invention. In fact, it is possible even the distance is shorter. In practical use, one can adopt an infrared signal having a more powerful transmission capacity to carry out the traffic information transmission and warning in hazardous condition. When the distance enters within the range of ultrasound measuring distance, the ultrasound part can start to operate, and start the safe travel control device in emergency situation so as to realize effective anti-crash and safe driving.
The Doppler effect, the characteristics and transmitting/receiving of ultrasound and infrared above-mentioned are known technologies in the relevant fields and are not described in detail in the present application. Also, the present invention has been described with references to a preferred embodiment thereof, and it should be noted that various other changes or modifications may be made without departing from the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200810216834.0 | Oct 2008 | CN | national |
| 200810216835.5 | Oct 2008 | CN | national |
| 200810216836.X | Oct 2008 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN2009/074388 | 10/10/2009 | WO | 00 | 4/7/2011 |
