Source: https://patents.google.com/patent/JP2007132768A/en
Timestamp: 2020-01-24 21:38:23
Document Index: 63011279

Matched Legal Cases: ['art, 125', 'art, 126', 'art, 127', 'art, 131', 'art, 132', 'art, 134', 'art, 135']

JP2007132768A - Vehicle-mounted radar system having communications function - Google Patents
Vehicle-mounted radar system having communications function Download PDF
JP2007132768A
JP2007132768A JP2005325546A JP2005325546A JP2007132768A JP 2007132768 A JP2007132768 A JP 2007132768A JP 2005325546 A JP2005325546 A JP 2005325546A JP 2005325546 A JP2005325546 A JP 2005325546A JP 2007132768 A JP2007132768 A JP 2007132768A
JP2005325546A
和彦 塙
2005-11-10 Application filed by Hitachi Ltd, 株式会社日立製作所 filed Critical Hitachi Ltd
2005-11-10 Priority to JP2005325546A priority Critical patent/JP2007132768A/en
2007-05-31 Publication of JP2007132768A publication Critical patent/JP2007132768A/en
G01S2013/93273—
When UWB radar is applied to a vehicle, it is necessary to study an optimal control method and mounting method.
The present invention uses a UWB having a communication function and a radar function. The distance between the vehicles in front of the obstacle is measured with a radar function, and a warning warning is given to the driver or a pre-crash operation is performed according to the distance. In addition, by using the communication function to notify each other's own vehicle position between the vehicles, measure the distance to the vehicle close to the vehicle regardless of disturbance, and issue a warning warning to the driver according to the distance, Alternatively, it is achieved by performing a pre-crash operation. Further, the influence of the other radio system is reduced by changing the use frequency and transmission power of the radar according to the vehicle position information.
The present invention relates to a radio terminal device having a radar function mounted on a high-speed moving body, and to a radar system having a communication function between the radio terminal devices.
Millimeter wave radar was put into practical use from around 1999 to increase driving safety in cars. This millimeter-wave radar makes it possible to measure the distance between vehicles more accurately even under bad weather than conventional infrared radars. The millimeter wave radar is mounted in front of the vehicle, and detects the inter-vehicle distance and relative speed between the preceding vehicle and the own vehicle from information obtained by the radar. Then, according to the detected inter-vehicle distance and relative speed, an operation such as controlling the inter-vehicle distance to be constant is performed.
However, its price is higher than that of infrared radar, so it is only applicable to some luxury cars. In addition, the millimeter wave radar is installed in front of the vehicle to detect the preceding vehicle, but it is difficult to grasp the vehicle in the lateral direction or the rear side from the directivity of the radio wave.
UWB (Ultra Wide Band), which has been developed for the purpose of next-generation wireless high-speed communication,
Standardization has been underway since 2002. When a transmitter / receiver that generates this UWB radio wave waveform is designed, the distance between the transmitter / receiver and the object is measured by measuring the round trip time of the pulse with the received wave when the pulse wave transmitted by itself is reflected on the object. It is also known that a radar function can be provided. Therefore, European industry consortium SARA (Short-range
In Automotive Radar frequency Allocation), short-range radar using UWB using a frequency in the 24 GHz band is being studied, and studies are also underway to mount UWB radar. In addition, the above-mentioned SARA is also considering that data is carried on UWB radar transmission / reception waves to perform platooning while performing inter-vehicle communication.
When using a wide frequency band such as UWB, it is necessary to limit the frequency according to the use environment in order to reduce the influence of radio wave interference with the existing wireless system. For this reason, there is also a movement to perform a plurality of frequency divisions (multiband) and restrict use for each frequency band according to the type of radio.
http://www.kuroda.elec.keio.ac.jp/projects/TeamUWB/chapter1.html "What is UWB (Ultra Wide Band)", read on June 28, 2005 "Development of Inter-Vehicle Communications Overseas-History and Present Status", Seki, Automobile Research Vol. 27, No. 1 (January 2005), p21-p26, Japan Automobile Research Institute
In a radar system using UWB communication, it is possible to directly measure distances from surrounding objects and perform wireless communication as a radar system. However, no consideration has been given to combining distance measurement with other vehicles around the vehicle in the short distance and vehicle-to-vehicle communication. Both radar function and vehicle-to-vehicle communication are compatible, and disturbances such as unnecessary reflections around the vehicle (clutter ) Strong transmission / reception is required.
The present invention uses UWB communication having a communication function and a radar function, and measures an inter-vehicle distance from a front obstacle or a vehicle by the radar function. In addition, by using the communication function, vehicles with UWB communication function notify each other's own vehicle position to measure the distance to the surrounding vehicles that are close to the own vehicle, and to the driver according to the distance. Issue a danger warning or perform a pre-crash action.
In addition, the present invention obtains the direction and distance from the position information superimposed on the radar wave from the other vehicle, and identifies the position from the radar wave other than the reflected wave of the radar wave transmitted by the own vehicle without depending on the disturbance. Make it possible.
According to the present invention, the position and state of each vehicle can be easily detected by a radar device using UWB communication in addition to the detection of obstacles existing in the vicinity.
Hereinafter, the present invention will be described by taking an in-vehicle radar device having an inter-vehicle communication function as an example.
An example of the configuration of an on-vehicle radar device using the present invention will be described with reference to FIG. A vehicle-mounted radar device 110 using the present invention is mounted on the host vehicle 100. The position information acquisition unit 125 mounted on the in-vehicle radar device 110 receives a signal from a GPS satellite via the antenna 124, measures the own vehicle position, and transmits the own vehicle position to the inter-vehicle measurement unit 126. In addition, although this position information acquisition part has shown GPS as an example, you may use another position information acquisition method.
In the in-vehicle radar device 110, the control unit 123 sends a radar wave transmission instruction to the radar transceiver 122 at a period or timing determined according to the traveling speed. The control unit 123 reads the timing at which this transmission instruction is given from the timer 135 and stores it as the transmission timing. In the radar transmitter / receiver 122, the transmission data generation unit 131 generates a pulse of a radar wave according to an instruction from the control unit 123, and generates transmission data including the obtained own vehicle position information and the vehicle ID of the own vehicle, A radar wave 140 in which transmission data is added to the pulse of the radar wave is transmitted by the transmitter 130 via the antenna 121A.
Radar waves are received by the radar transceiver 122 via the receiving antenna 121B. The mounting position of the receiving antenna 121B of the in-vehicle radar device is set at a position where communication with the front and rear of the vehicle is easy, such as on the roof of the vehicle or on the dashboard. The received radar wave is converted to a low frequency and amplified by the receiving unit 132, and a received signal is generated. The received signal is demodulated by the demodulating unit 133, and the ID identifying unit compares the vehicle ID of the own vehicle with the vehicle ID of the received signal, and the radar wave transmitted from another vehicle or whether it is a reflected wave of the radar wave transmitted from the own vehicle. To identify. In the case of a received signal of a radar wave transmitted from the host vehicle, the pattern detection unit 134 obtains a cross-correlation with a known waveform pattern having a predetermined length, and eliminates the influence of multipath. Then, the control unit 123 is triggered. The control unit 123 acquires the trigger timing from the timer 135 and stores it as the reception timing. The transmission timing and the reception timing are sent to the inter-vehicle measurement unit 126. The inter-vehicle measuring unit 126 calculates the inter-vehicle distance A between the host vehicle 100 and the vehicle 101 from the time difference between the transmission timing and the reception timing of the radar wave sent from the control unit 123.
Furthermore, when the received signal is a radar wave transmitted from an in-vehicle radar device mounted on another vehicle, the received signal demodulated by the demodulator 133 is received, and the vehicle ID and the position information of the other vehicle are received from the received signal. It is taken out and transmitted to the inter-vehicle distance measuring unit 126. The inter-vehicle measuring unit 126 calculates the inter-vehicle distance B from the transmitted position information of the other vehicle and the own vehicle position information obtained from the position information acquiring unit 125. It is assumed that there are a plurality of other vehicles around the host vehicle, and the inter-vehicle distance B is acquired by the number of signals received by the reception unit 132 of the radar.
The control unit 123 selects the inter-vehicle distance C having the shortest distance from the inter-vehicle distance A and the plurality of inter-vehicle distances B obtained by the inter-vehicle measurement unit 126. This inter-vehicle distance C is transmitted to an external device via the network 127. In addition, when the position of the vehicle with the shortest distance between vehicles is obtained from the vehicle information obtained from the radar wave transmitted by this vehicle, the current position of the corresponding vehicle is transmitted to the external device together with the distance between the vehicles. By doing this, it is possible to know in which direction the vehicle is approaching even with this external device. Alternatively, when the inter-vehicle distance C is equal to or less than the specified value, it is determined that there is a risk of vehicle contact, and a signal indicating the danger is transmitted to the external device via the network 127. Examples of this external device include a warning device having a warning function and a safety device having a pre-crash safety function. Examples of this external device include a warning device having a warning function and a safety device having a pre-crash safety function. There is.
In an example in which a warning device is connected as an external device, the calculated inter-vehicle distance C, which is the shortest distance, is transmitted to the warning function via the control unit 123. In the warning function, when the obtained inter-vehicle distance C is equal to or less than a predetermined distance, a warning is given that a nearby vehicle is approaching the driver by voice, sound, display, or the like.
In the example in which a safety device is connected as an external device, the calculated inter-vehicle distance C is transmitted to the pre-crash safety function via the control unit 123. In the pre-crash safety function, the driver protection function of the host vehicle is activated according to the inter-vehicle distance C. Examples of the driver protection function include fixing the driver by winding the seat belt before the collision, realizing rapid braking by pressurizing the brake hydraulic pressure, and starting the airbag.
Next, other configuration examples of the on-vehicle radar device are shown in FIGS. In the in-vehicle radar device of FIG. 2, unlike FIG. 1, an example in which the antenna 121 </ b> C is shared by the transmission unit 130 and the reception unit 132 is shown. Normally, the antenna 121C is connected to the reception unit 132 by the selector 136, but the selector 136 connects the antenna 121C and the transmission unit 130 only when the transmission unit 130 performs a transmission operation. In this case, the selector 136 is configured to switch the connection destination of the antenna 121C in accordance with an instruction from the transmission unit 130. When a circulator is used as the selector 136, when a radio wave is received by the antenna 121C, the received reception wave is sent to the receiving unit 132. When the transmitting unit 130 sends a signal by a transmission operation, this signal is sent to the antenna 121C. The transmitted wave and the received wave are distributed to the antenna 121C and the receiving unit 132.
3 shows a case where the position information acquisition unit 185 is outside the in-vehicle radar device 110, unlike FIG. Here, a signal from a GPS satellite is received via the antenna 186, the position of the vehicle is measured by the position information acquisition unit 185 in the navigation device 312, and the obtained position information is controlled via a network such as CAN. 123.
Next, the transmission timing of the radar wave transmitted from the in-vehicle radar device 110 will be described with reference to FIG. In the graph shown in FIG. 5A, the horizontal axis represents time, and the vertical axis represents travel speed. Three examples are shown from the top: high-speed driving, medium-speed driving, and low-speed driving. In this graph, the transmission time of the radar wave 151 is described, and since the moving speed of the vehicle is high when traveling at a high speed, the radar wave is transmitted in order to frequently measure the inter-vehicle distance by transmitting the radar wave in a short period. The interval is set short. On the other hand, when the vehicle is traveling at a low speed, the moving speed of the vehicle is slow, so a radar wave is transmitted at a long period to reduce the frequency of measuring the distance between vehicles, thereby reducing power consumption. Note that the vehicle speed is a method in which the control unit 123 refers to a vehicle speed pulse via the network 127, or refers to a movement distance per unit time of the vehicle position information periodically obtained from the position information acquisition unit 125. You can find out at In this embodiment, three modes of high speed / medium speed / low speed are used, but two modes of high speed / low speed may be used, and four modes or more may be used. Furthermore, it is also within the scope of the present invention to stop the transmission of radar waves in order to reduce power consumption when stopping.
The control unit 123 receives vehicle speed information from the vehicle control device via the network, determines the transmission interval of the radar wave based on the relationship shown in the graph of FIG. A transmission timing is instructed to the generation unit 131. The transmission timing instructed at this time is to transmit a radar wave at a predetermined interval set for low-speed driving until the vehicle reaches a certain speed, and then shorten the transmission interval as the vehicle speed increases. However, even when the vehicle speed exceeds a predetermined value, the interval between the radar waves 151 is set at a lower limit of, for example, an interval of about 10 msec as a resolution necessary for control using the inter-vehicle distance information obtained as a result of receiving the reflected wave. And In addition, in order to secure a data transmission time via the network 127 for inter-vehicle communication, the transmission timing of the radar wave is controlled so as not to be shortened by a certain interval or more.
FIG. 4 shows a waveform example of a pulse train 160 of radar waves. This example shows that the pulse 161 is transmitted at a constant pulse time interval 162. The round-trip distance between the host vehicle and the preceding vehicle is calculated from the timing at which this pulse train 160 is transmitted and the time difference at which the pulse train is reflected by the preceding vehicle, and the inter-vehicle distance is obtained.
Positioning frequency of the own vehicle position in the position information acquisition unit 125 mounted on the in-vehicle radar device 110 is synchronized with the transmission timing of the radar wave, and the vehicle moving speed is high when traveling at high speed. Measure the vehicle position. In addition, when the vehicle is traveling at a low speed, the moving speed of the vehicle is slow.
As shown in FIG. 5A, in the radar wave 151 transmitted from the in-vehicle radar device 110, vehicle information 153 such as the vehicle position is superimposed on the pulse train 160 used for the radar function. Is shown. At this time, the own vehicle position information may be added for each transmission time of the radar wave 151, or the superposition frequency may be lowered. This superposition frequency can be changed according to the vehicle speed.
FIG. 6 shows a format example of the radar wave. First, a preamble portion 171 composed of a known waveform pattern, then a unique word portion (UW) 172 composed of a predetermined data string indicating the beginning of vehicle information data, and then the vehicle ID and position of the vehicle. First data portion 173 including information, then CRC (Cyclic Redundancy Check) redundant data 174 for error detection of the first data portion, then second data portion 175, and finally for error detection CRC of the second data portion Continue with redundant data 176. In this format, the inter-vehicle distance from the preceding vehicle is measured using the pulse train 160 composed of the pulses shown in FIG. 3 as the preamble portion 171, and the vehicle ID and position information of the host vehicle are measured in the first data portion 173. To the surrounding vehicle. The second data part is used for transmission of other information, such as specifying the vehicle ID of the vehicle that is the transmission destination. In this way, a UWB radar that is strong against clutter is realized by adopting a format that attaches error correction information to each of the two parts of the first data part that is the vehicle position information part and the second data part that is the inter-vehicle communication data part. be able to.
In the in-vehicle radar device 110 of FIG. 1, the inter-vehicle distance calculated by the inter-vehicle measuring unit 126 is transmitted to the driver warning function via the control unit 123 and the network 127. In the warning function, the obtained inter-vehicle distance is predetermined. When the distance is less than or equal to the distance, a warning is given that a nearby vehicle is approaching the driver by voice, sound, or display. Alternatively, a pre-crash safety function is added instead of the warning function, and in the pre-crash safety function, the driver protection function of the host vehicle is activated according to the inter-vehicle distance. Examples of the driver protection function include fixing the driver by winding the seat belt before the collision, realizing rapid braking by pressurizing the brake hydraulic pressure, and starting the airbag.
Next, a processing flow for measuring the inter-vehicle distance according to the instruction from the control unit 123 will be described with reference to FIG. First, the control unit 123 sets the operation cycle of the radar transceiver 122 and the position information acquisition unit 125 based on the vehicle speed (501). Here, based on the speed information obtained from the external device (for example, vehicle speed pulse), the control unit 123 sends the radar transceiver 122 and the position information acquisition unit 125 to the radar wave transmission cycle and the positioning result acquisition cycle, respectively. Set. The radar transceiver 122 and the position information acquisition unit 125 each operate at a set cycle. Note that, as in the configuration illustrated in FIG. 3, when using the results obtained by the position information acquisition unit 185 of the navigation device 312, the control unit 123 sets a cycle for reading the positioning results from the network 127. become.
Next, the control unit 123 reads the vehicle position information obtained from the position information acquisition unit 125 (502) and stores it in the memory in the control unit 123 (503). Then, in order to measure the inter-vehicle distance from the preceding vehicle with a radar, the control unit 123 sends the vehicle ID of the own vehicle and the stored vehicle position information to the vehicle data generation unit 182 of the transmission data generation unit 131, The radar wave generation unit 181 is instructed to transmit a radar wave, and the transmission timing acquired from the timer 135 is transmitted to the inter-vehicle measurement unit 126 (504). Next, the data sent to the vehicle data generation unit 182 is combined with the pulse train generated by the radar wave generation unit 181 by the combination unit 183 and transmitted from the transmission unit 130 at a prescribed timing.
The radar wave transmitted from the transmitting antenna 121A is reflected by a surrounding object and received by the receiving antenna 121B (505). The received radar wave may be a reflected wave of the radar wave transmitted by the own vehicle, or may be a radar wave transmitted by another vehicle. Therefore, the received radar wave signal is demodulated by the demodulator 133, and the vehicle ID included in the signal received by the ID identification unit 184 is compared with the vehicle ID of the host vehicle (506). If the vehicle ID of the host vehicle is detected, it is recognized that the signal is a signal for measuring the distance between the vehicle and a legitimate vehicle ahead, and is notified to the pattern detection unit 134 and the control unit 123 (507). In response to this notification, the pattern detection unit 134 transmits the reception timing obtained from the peak value of the cross-correlation between the received wave and the transmitted radar wave preamble unit 171 to the control unit 123. In addition, when the vehicle ID of the own vehicle is not detected in the received signal, it is considered that the inter-vehicle distance measurement by the radar function has failed.
If the vehicle ID of the host vehicle is detected, the control unit 123 sends the transmission timing and the reception timing obtained from the pattern detection unit 134 to the inter-vehicle measurement unit 126, and the inter-vehicle measurement unit 126 transmits these transmission timings and reception timings. The distance value obtained by multiplying the time difference by the speed of light is halved to calculate the inter-vehicle distance from the vehicle reflecting the radar wave, and the result is transmitted to the control unit 123. The control unit 123 records the obtained distance A between the vehicle and the internal memory (508).
When the vehicle ID of the own vehicle is not detected in the received signal, the inter-vehicle distance measurement with another vehicle is performed without using the radar function. The control unit 123 obtains the vehicle ID and vehicle position information from the reception signal demodulated by the demodulation unit 133. If this vehicle ID is not the vehicle ID of the own vehicle, the vehicle ID and vehicle position information obtained from the received signal are recorded in the internal memory (512). Further, the vehicle position information and the own vehicle position information are sent to the inter-vehicle distance measuring unit 126, and the vehicle position is obtained by a radar wave from the difference between the position information of the two vehicles. The inter-vehicle distance B with the vehicle notified by the inter-vehicle measuring unit 126 is recorded in the internal memory (513). At this time, since it is assumed that there are a plurality of other vehicles around the vehicle, a plurality of pieces of information that are set by the vehicle ID and the vehicle position information may be recorded.
From the inter-vehicle distance A or inter-vehicle distance B obtained by receiving the radar wave, the control unit 123 calculates the shortest inter-vehicle distance C (509). Next, the control unit 123 determines whether the inter-vehicle distance C is equal to or less than a specified value (510), and if it is equal to or less than the specified value, issues a warning instruction to an external device (for example, a warning device) (511).
Next, referring to FIG. 8, an embodiment of the vehicle travel control system in the case where a plurality of on-vehicle radar devices shown in FIG. 3 are attached will be described. It is assumed that the vehicle body on which the radar is mounted is equipped with a radar A302 in front of the normal traveling direction and a radar D305 behind. Two or more radars may be attached, but it is desirable to attach at least a range that covers the front and rear.
The ACC device 311 which is a radar and vehicle travel control unit is connected by a network. The above-described radar A302 and radar D305 are connected to the in-vehicle network A313. In addition, an ACC device 311 and a navigation device 312 are connected to the in-vehicle network B314. Further, the integrated unit 310 is connected to both in-vehicle networks A and B. This integrated unit 310 has the functions of the control unit 123 and the inter-vehicle measurement unit 126 of the in-vehicle radar device shown in FIG. 1, and integrates the control of each radar function into one. Moreover, the information of each radar A and D is collected and processed, and the gateway function between in-vehicle network A313 and in-vehicle network B314 is also provided.
For example, the collision time is calculated from the results of relative speed, distance measurement, and heading between the host vehicle and the other vehicle, and it is necessary to determine whether or not to perform a pre-crash operation on the other vehicle with the shortest collision time or the own vehicle. Accordingly, vehicle control information (brake command, steering avoidance command) for pre-crash is transmitted to the ACC device 311 and an alarm display or warning sound generation instruction is transmitted to the navigation device 312. Further, the integrated unit 310 instructs the radars A and D to change the output and frequency of the transmission radio wave from the navigation device 312 based on the vehicle position information (GPS information). This specific changing method will be described later.
In this embodiment, there are two network systems, an in-vehicle network A313 connected to the radars A and D, and an in-vehicle network B314 connected to the ACC device 311 and the navigation device 312. This is for the purpose of distributing the network communication load. If the network load is low, the radars A and D and the ACC device 311 and the navigation device 312 may all be connected to one network. Also, the function of the integrated unit 310 can be incorporated in the radars A and D, and the integrated unit 310 can be omitted.
A steering control device 183, an accelerator control device 181 and a brake control device 182 are connected to the ACC device 311 to instruct control parameters (steering angle, accelerator opening, brake thrust command value) for each. Each actuator is operated as necessary for each vehicle control such as follow-up running, collision avoidance, and pre-collision control (pre-crash). The navigation device 312, the integrated unit 310, and the ACC device 311 are connected to the in-vehicle network B 314 and exchange information. The integrated unit 310 is further connected to the in-vehicle network A313, obtains information from the radars A and D, and instructs control of the radar transmission signal.
Since UWB communication uses a wideband frequency, it is necessary to avoid radio wave interference with other existing wireless systems. Therefore, UWB communication uses a wide frequency band, but suppresses transmission power and suppresses the occurrence of radio wave interference with other wireless systems. However, if the transmission power is low, the reachable range is shortened. . As a technology to effectively use frequency resources by avoiding radio wave interference, the concept of cognitive radio that actively uses unused frequency bands in each region is ”Communication”, Nikkei Electronics, October 25, 2004 issue, p43.
Even in the on-vehicle radar device using the present invention, it is important to coexist with other radio systems by avoiding radio wave interference with surrounding radio systems so as not to affect other radio systems. Therefore, in the present invention, an in-vehicle wireless device or an obstacle detection device is realized which is characterized by changing a used frequency band and signal transmission power based on position information on a predetermined map. And in the radar function of multi-band UWB communication and inter-vehicle communication, the frequency band to be used is made variable and the frequency band to be used is appropriately selected for each area, and it is not used without affecting the local radio equipment. The transmission power is controlled according to the frequency band to be used. In this UWB communication, as the vehicle moves, the frequency band used by the surrounding wireless system is obtained from the information on the current position detected by the position information acquisition unit that detects the position of the host vehicle. Communicate with a wider range of vehicles by increasing the transmission power of this frequency band and expanding the communicable distance by setting the available frequency available in each region according to the usage environment to the frequency band used for UWB communication. It is also possible to extend the reach distance.
Accordingly, in the present invention, even when the vehicle moves, the influence on other wireless systems is suppressed by detecting the frequency used by the position information acquisition unit that detects the position of the host vehicle and the surrounding wireless system. Thus, it is possible to control the specification frequency band and transmission power in the radar function and the inter-vehicle communication. Even when the vehicle moves, radio wave interference with surrounding wireless systems can be avoided.
FIG. 9 shows the relationship between the vehicle position information, the radar use frequency band, and the transmission power. The in-vehicle radar device 110 performs control to change the frequency band and transmission power based on the GPS information. The navigation device 312 pre-records regional information with a limited frequency band as a database. In this database, frequency bands used for each mesh in each region are registered. In the example of FIG. 9, for the map mesh around the satellite communication base station, the frequency band of the radio wave used by the base station is registered as the limited frequency band, and for the map mesh around the general broadcast base station, The frequency band used in the broadcast base station is registered as a limited frequency band. The navigation device 312 refers to the mesh including the measured current position, reads a frequency band whose use is restricted in the area, and transmits it to the radar device 110 via the network. Receiving this information, the control unit 123 outputs a value for the transmission data generation unit 131 so that the value obtained by integrating the usable frequency band and the power spectrum of the usable frequency band does not exceed the limit output. Instruct.
Alternatively, as shown in FIG. 10, the navigation device 312 records in advance, as a database, area information having a restriction on usable frequency bands. In FIG. 10, the information on the frequency restriction area defines an area surrounded by the position coordinates of the point expressed by longitude-latitude information as an area where the frequency band is restricted. An ID, a position coordinate group, and a frequency limit band are associated with each enclosed area. Based on the longitude / latitude information acquired from the GPS, it can be determined from a known geometric formula (primary linear equation) whether it is inside or outside the area.
In the radio wave usage statuses A and B in the frequency limit areas A and B of FIG. 9, the frequency band that can be used by the radar by UWB communication is limited, and the allowable value of the transmission power peak value increases as the usable frequency band becomes narrower. It shows that it becomes. In the current specific low-power radio equipment (output from the antenna) is 10 mW or less, if the modulation frequency band is widened, it is necessary to lower the transmission power peak value. Outside the frequency limit range (radio wave usage status C), the transmission power is reduced and the frequency band is widened for setting.
FIG. 11 shows a frequency restriction and transmission power setting procedure. The position information acquisition units 125 and 185 using GPS or the like acquire the longitude and latitude of the host vehicle (4301). Based on the acquired position information of the own vehicle, a frequency limit area at the current position is searched from the database shown in FIG. 10 (4302). If it is determined from this search result that the frequency is restricted (4303), a usable transmission frequency band is calculated (4304). The peak power is limited so that the obtained average power in the usable transmission frequency band is equivalent to a reference output upper limit (for example, 10 mW / 1M) (4305). Next, the type of data to be transmitted is selected. At this time, since the amount of information that can be transferred is also limited by the width of the frequency band, data types with higher priority are selected in order (4306). The radar function and inter-vehicle communication function by UWB communication is started with the frequency band and transmission power selected in this way (4307). If it is determined that the current position is an area that is not subject to frequency restriction, a predetermined frequency band and transmission power determined in advance are selected, and the process proceeds to processing 4306.
FIG. 12 illustrates an example of UWB communication in which a predetermined frequency band and transmission power that are determined in advance are assigned to the 24.0 to 28.0 GHz band as the use frequency, and the output upper limit is 10 mW / 1M. FIG. 12 shows a use frequency spectrum of the radar device outside the frequency limit region C (the radio wave use status C) that is not subject to frequency limit. In the case of 8-channel multiband (0.5 GHz width for each channel) UWB communication using a bandwidth of 4.0 GHz, the peak power is 10 mW / (4.0 GHz / 1.0 MHz) = 2. 5μW
FIG. 13 shows the spectrum of the radar device in the frequency limit area A under the same output upper limit as in the example shown in FIG. Since the 26.7 to 26.8 GHz band is used in another existing wireless system, the use of the 26.5 to 27.0 GHz band corresponding to the sixth channel is stopped and the remaining seven channels are used. The peak power in this case is
10 mW / (3.5 GHz / 1.0 MHz) = 2.86 μW
FIG. 14 shows a spectrum of the radar device in the frequency limit region B under the same output upper limit as that in the example shown in FIG. Here, since the 24.6 to 26.3 GHz band is used in another existing wireless system, the use of the overlapping 24.5 to 26.5 GHz band (for 4 channels) is stopped, and the remaining 4 channels are used. Is used for UWB communication. The peak power in this case is
10 mW / (2.0 GHz / 1.0 MHz) = 5 μW
Here, the peak power of 2.5 μW outside the frequency limit region C and the peak power of 5 μW in the frequency limit region B are in a one-to-√2 relationship in terms of voltage. In other words, the latter is considered to have about 1.41 times the radio wave reach compared to the former, that is, even if the inter-vehicle distance is 1.41 times longer, the distance of the vehicle ahead can be measured by radar with the same S / N ratio. It becomes.
FIG. 15 explains the principle of data communication in each frequency channel. This figure shows an image in which a pulse wave having the center frequency of each channel of 1 to 4 ch is transmitted on the time axis, and the waveform of the pulse wave is an image of the amplitude of the radio field. If a time zone without a pulse is expressed as 0 and a time zone with a pulse is expressed as 1, 0/1 data communication is possible. The transmitting side transmits frequency bands (ch) having different center frequencies at the same time, and the receiving side separates each frequency band and extracts data. This method is the same as the UWB communication technique using ODFM modulation.
By widening the frequency band used for UWB communication, the data transfer rate in inter-vehicle communication increases, but if the channel used is limited, communication data with lower priority is stopped and data with higher priority is allocated. There is a need. Communication contents used for inter-vehicle communication include (1) vehicle travel control information (particularly information related to travel stability, forward vehicle follow-up performance and safety), and (2) information necessary for driver convenience services. Conceivable. The data sent for each communication content can be given a priority as shown in FIG. Priority 1 (vehicle travel control information) is the minimum information necessary for travel control using inter-vehicle communication. In this example, each channel is used for transmission and reception with a preceding vehicle or a rear vehicle (two channels in total). Assign. In accordance with the number of usable frequency bands (number of channels) corresponding to the frequency limit area, assignment is performed in descending order of priority of the data types shown in FIG. In this example, priorities are determined in order of vehicle travel control information, voice call, in-car image transfer (videophone), car-to-car, and road-to-car Internet communication, and assigned in order.
If only one channel band can be allocated as a usable frequency band, the inter-vehicle communication function itself may be stopped and only the radar function may be operated. When only one channel band is used, the transmission power can be amplified as compared with the case where a plurality of channels are used as described above. For this reason, it is possible to perform a follow-up running using only the information of the radar function with a wider inter-vehicle distance than when using a plurality of channels.
On the other hand, if two or more channels can be assigned as usable frequency bands, vehicle control with good responsiveness can be performed by sending and receiving vehicle travel control information to and from surrounding vehicles. It is possible to follow the vehicle with a shorter inter-vehicle distance than to follow the function only. For example, assuming that the measurement delay of the inter-vehicle distance and relative speed by the radar function takes 1 second, and the vehicle speed information acquisition of the preceding vehicle by the inter-vehicle communication is set to 0.05 sec, the inter-vehicle time (= It is necessary to secure an extra (vehicle distance / relative speed) by 1-0.05 = 0.95 sec.
As described above, when the inter-vehicle distance is shortened by using the vehicle travel control information by the inter-vehicle communication, it is possible to receive the benefit of reducing the air resistance to the host vehicle by the preceding vehicle. In other words, reducing the running resistance can be expected to reduce fuel consumption and reduce mechanical performance degradation of the vehicle. In addition, shortening the inter-vehicle distance can also increase the number of vehicles traveling per route length unit, so it can be expected to ease traffic congestion.
Next, platooning by a plurality of vehicles equipped with the above-described on-vehicle radar device will be described with reference to FIG. Although four vehicles 301 to 304 are shown in FIG. 17, the number of vehicles may be two or more. Further, each vehicle has the same function, and the on-vehicle radars 302 and 305 shown in FIG. 8, the accelerator control device 181, the brake control device 182, the steering control device 183, and the vehicle group approach / A disconnect switch is connected to the network 127. In response to an instruction from the integrated unit 310, the acceleration control device 181 accelerates the vehicle, the brake control device 182 decelerates the vehicle, and the steering control device 183 changes the traveling direction.
First, a situation where a new vehicle 304 enters and joins a group of vehicles traveling in a row will be described. In the situation 201, the vehicles 301 to 303 are traveling in the convoy travel mode. In this situation, the vehicle 302 measures the inter-vehicle distance from the vehicle 301, the vehicle 303 measures the inter-vehicle distance from the vehicle 302, and the inter-vehicle distance from the preceding vehicle is measured by the above-described in-vehicle radar device, and the inter-vehicle distance becomes constant. Vehicle control is performed. Since the vehicle 301 is at the head, the driver performs human driving, but the traveling direction is transmitted to the following vehicles 302 and 303 by the communication function of the in-vehicle radar device. The vehicles 302 and 303 are appropriately operated based on the obtained traveling direction information.
Further, the vehicle 301 leading the platoon sets the transmission power of the radar attached ahead to detect the obstacle on the road farther than the subsequent vehicles 302 and 303 in the platoon, and sets the maximum allowable value. The vehicles 302 and 303 are set to the minimum transmission output and detection range that secure the inter-vehicle communication and the current inter-vehicle distance. This reduces the possibility of clutter reduction, interference with other wireless systems, or the possibility of radio interference in the surrounding environment by controlling the transmission power of the radar device and the transmission frequency band using the vehicle position information. can do.
In this situation, when the vehicle 304 equipped with the on-vehicle radar device joins the platoon, the driver of the vehicle 304 turns on the fleet entry / exit switch to switch the fleet to the vehicles 301 and 302 before and after the platooning. Get permission. By turning on this switch, the vehicle ID and position information of the vehicle 304 and vehicle travel control information are transmitted from the in-vehicle radar device of the vehicle 304 to the vehicles 301 to 303 forming the vehicle group. The appropriate inter-vehicle distance and vehicle speed of the convoy vehicle group are confirmed by the vehicle travel control information sent to determine whether or not a predetermined time can be maintained.
For example, if the vehicle running performance (acceleration performance, deceleration performance) of the vehicle 304 deviates significantly from the standard for the convoy vehicle group, permission to join cannot be obtained. It is advantageous for the platooning group to have small variations in at least acceleration and deceleration performance so that individual behavior can be easily controlled. When permitting the vehicle 304 to join the platoon, the vehicle 302 that is the vehicle closest to the vehicle 304 from the transmitted position information transmits an entry permission signal to the platoon to the vehicle 304 and 302 controls the distance between the vehicle 301 and the preceding vehicle so that the vehicle 304 can enter. This stage is indicated by situation 202.
Thereafter, the driver of the vehicle 304 turns the steering wheel and guides the vehicle 304 between the vehicle 301 and the vehicle 302. Thereafter, a situation 203 in which the vehicle 304 has joined the platoon is shown. When the vehicle 302 recognizes that the vehicle position transmitted by the vehicle 304 is within an appropriate range between the vehicle 301 and the vehicle 302, the vehicle 302 notifies the vehicle 304 of completion of joining the platoon. Upon receiving this notification, the vehicle 304 starts control so that the inter-vehicle distance from the vehicle 301 ahead is an appropriate distance. In addition, the vehicle 302 located behind the vehicle 304 recognizes the preceding vehicle as the vehicle 304 and performs control so that an appropriate inter-vehicle distance is obtained. Thereby, the convoy travel by the vehicles 301-304 is implement | achieved.
Next, a situation in which the vehicle 304 leaves the group of vehicles that are traveling in a row will be described. The status of this row running is indicated by status 203. This is an operation when the vehicle 304 leaves the platoon for reasons such as when approaching the vicinity of the destination of the route set in advance in the navigation device or the like, and notifies the driver of the departure from the platooning in advance. Here, the driver of the vehicle 304 visually checks the right lane, confirms safety, and then turns the steering wheel to the right. Upon detecting that the driver's own vehicle operation (handle operation, brake operation, accelerator operation, etc.) has started, a departure signal including the vehicle ID is transmitted from the in-vehicle radar device mounted on the vehicle 304, Release the convoy travel control of the vehicle 304.
Also, several tens of seconds before the driver is notified of the state in which the vehicle 304 leaves the platoon, information that the vehicle 304 leaves is transmitted in advance to the subsequent vehicle, and the subsequent vehicle ensures a sufficiently safe distance between the vehicles. Prepare in advance. As a result, the vehicle 304 notifies the driver of leaving the platooning after a sufficient inter-vehicle distance from the following vehicle 302 is secured. The vehicle 302 recognizes that the vehicle ahead of the host vehicle has entered the leaving operation from the vehicle ID of the received leaving signal. At this time, the vehicle 302 stops the inter-vehicle distance control with the preceding vehicle and controls the vehicle speed to be constant. Thereafter, the vehicle 302 repeatedly receives the positional information of the vehicle 304 transmitted by the vehicle 304, and detects that the vehicle 304 has moved away from the formation by a certain distance or more. When the vehicle 304 leaves the platoon, the situation 202 is obtained. When the vehicle 302 recognizes the departure of the vehicle 304, the in-vehicle radar device mounted on the vehicle 302 controls the inter-vehicle distance with the preceding vehicle to be a predetermined distance, and the vehicle 301 is in a row running, The state shown in the situation 201 is obtained. Similarly, when the vehicle 304 cannot maintain the vehicle speed defined in the platooning due to a malfunction, a warning is transmitted to the succeeding vehicle 302 to ensure an appropriate inter-vehicle distance before leaving. To do.
It is a figure which shows the structural example of the vehicle-mounted radar apparatus using this invention. It is a figure which shows the other structural example of the vehicle-mounted radar apparatus using this invention. It is a figure which shows the other structural example of the vehicle-mounted radar apparatus using this invention. It is a figure which shows an example of the radar waveform in the Example using this invention. It is a figure which shows the example of a transmission period of the radar wave in the Example using this invention. It is a figure which shows the format example of the radar wave in the Example using this invention. It is a figure which shows the process of the control part in the vehicle-mounted radar apparatus using this invention. It is a figure which shows the structure of a vehicle travel control system. It is a figure which shows the use frequency and output switching of a radar. It is a figure which shows the database of a frequency limiting area. It is a figure which shows the processing flow of use frequency band switching. It is a figure which shows the use frequency band of C outside a frequency limit area. It is a figure which shows the use frequency band of the frequency limitation area A. It is a figure which shows the use frequency band of the frequency limitation area B. FIG. It is a figure which shows the data transfer by each frequency channel. It is a figure which shows the priority of vehicle-to-vehicle communication data. It is a figure which shows the approaching / leaving of the vehicle to the formation running in this invention.
DESCRIPTION OF SYMBOLS 110 ... Car-mounted radar apparatus, 122 ... Radar transmitter / receiver, 123 ... Control part, 125 ... Position information acquisition part, 126 ... Inter-vehicle measurement part, 127 ... Network, 130 ... Transmission part, 131 ... Transmission data generation part, 132 ... Reception part DESCRIPTION OF SYMBOLS 133 ... Demodulation part, 134 ... Pattern detection part, 135 ... Timer, 136 ... Selector, 151 ... Radar wave, 310 ... Integrated unit, 311 ... ACC apparatus, 312 ... Navi apparatus.
In-vehicle radar device that has a transmission / reception unit that transmits and receives radar waves and measures the distance between the vehicle and the object to be measured,
A positioning unit for positioning the position information of the own vehicle;
A transmission data generation unit that generates a radar wave in which vehicle information including at least the own vehicle ID and position information of the own vehicle is added to the generated radar wave pulse;
When the received wave is not a reflected wave of the radar wave transmitted by the in-vehicle radar device, a received wave identifying unit that extracts vehicle information of the received wave;
When the received wave is a reflected wave of a radar wave transmitted by the in-vehicle radar device, the distance from the delay time of the received wave to the object to be measured is obtained, and the received wave is reflected from the radar wave transmitted by the in-vehicle radar device. An in-vehicle radar device comprising: an inter-vehicle measuring unit that obtains a distance to the vehicle based on the extracted vehicle information when it is not a wave.
In the on-vehicle radar device according to claim 1,
The on-vehicle radar device, wherein the transmission data generation unit changes a transmission period of the radar wave according to a traveling speed of the own vehicle.
The in-vehicle radar device, wherein the transmission data generation unit generates a radar wave in which a signal corresponding to the vehicle information is added to a signal having a waveform in which the same waveform is repeated at a constant period.
The inter-vehicle measurement unit obtains the distance and direction from the vehicle that has transmitted the reception wave from the position information included in the vehicle information extracted by the reception wave identification unit and the position information of the host vehicle by the positioning unit. In-vehicle radar device.
A transmitter for sending radar waves from a transmitting antenna;
In a vehicle-to-vehicle communication device comprising a receiver that receives a radar wave via a receiving antenna,
A transmission data generation unit that generates a radar wave in which vehicle information including at least position information by the positioning unit and the vehicle ID is added to the generated radar wave pulse;
A control unit for designating transmission timing of the generated radar wave;
Based on the vehicle ID of the received wave received by the receiver, a received wave identifying unit that extracts vehicle information of the received wave having a vehicle ID different from the own vehicle ID;
An inter-vehicle distance measurement unit that obtains a distance and a direction from the vehicle that transmitted the vehicle information based on the position information included in the extracted vehicle information and the position information of the host vehicle by the positioning unit is provided. Inter-vehicle communication device.
In the inter-vehicle communication device according to claim 5,
The said transmission data production | generation part changes the transmission period of the said radar wave according to the traveling speed of the own vehicle, The inter-vehicle communication apparatus characterized by the above-mentioned.
The said transmission data generation part produces | generates the radar wave containing the signal corresponding to the said vehicle information following the signal of the waveform in which the same waveform repeats with a fixed period, The inter-vehicle communication apparatus characterized by the above-mentioned.
The radar wave uses a plurality of frequency bands,
Map information that defines the frequency to be used based on longitude and latitude,
A vehicle position measuring means for measuring the vehicle position;
An in-vehicle laser device comprising: control means for changing the transmission / reception frequency band to be used according to a use frequency of the map information according to position information by the own vehicle position measurement means.
The on-vehicle radar device according to claim 8, wherein the control means includes:
An in-vehicle laser device that changes an output of a transmission radio wave according to the transmission / reception frequency band to be used.
The laser wave uses a plurality of frequency bands,
An inter-vehicle communication apparatus comprising: a control unit that changes the transmission / reception frequency band to be used according to a use frequency of the map information according to position information by the own vehicle position measurement unit.
The inter-vehicle communication device according to claim 10, wherein the control means includes:
A vehicle-to-vehicle communication device that changes a data type to be transmitted according to the transmission / reception frequency band to be used.
JP2005325546A 2005-11-10 2005-11-10 Vehicle-mounted radar system having communications function Withdrawn JP2007132768A (en)
JP2005325546A JP2007132768A (en) 2005-11-10 2005-11-10 Vehicle-mounted radar system having communications function
US11/594,947 US20070164896A1 (en) 2005-11-10 2006-11-09 In-vehicle radar device and communication device
EP06023461A EP1785744A1 (en) 2005-11-10 2006-11-10 In-vehicle radar device and communication device
JP2007132768A true JP2007132768A (en) 2007-05-31
ID=37747473
JP2005325546A Withdrawn JP2007132768A (en) 2005-11-10 2005-11-10 Vehicle-mounted radar system having communications function
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