JP2007155551A - Onboard radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely detect relative relationships between other vehicles and one's own vehicle, even when mutual interference between its electric wave and electric waves being transmitted signals emitted by the other vehicles occurs. <P>SOLUTION: The electric wave whose frequency is modulated, wherein radar regions to be emitted by first modulation width and cooperating-among-vehicles regions to be emitted by second modulation width narrower than the first modulation width appear alternately by a predetermined time period, is outputted as a transmission signal. In addition, a beat signal having as a fluctuation frequency the difference in frequency between the transmission signal and a received signal, is generated. Moreover, if the amplitude of fluctuation of the beat signal is larger than a predetermined minimum threshold, when the output state of the transmission signal is in the cooperating-among-vehicles region, it is judged that electric-wave interference between the transmission signal of the own vehicle and a transmission signal of another vehicle occurs, and the transmission timing of the transmission signal of the own vehicle is changed so as to diminish the phase difference between both signals. A relative distance between the own vehicle and the other vehicle is detected on the basis of the difference in phase between the transmission signal and the received signal, after the transmission timing is changed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an on-vehicle radar device, and more particularly, to an on-vehicle radar device that detects an object using a beat signal obtained from a frequency-modulated transmission signal and a reception signal.

2. Description of the Related Art Conventionally, an in-vehicle radar device that is equipped with a millimeter wave radar and detects a relative distance and a relative speed between the own vehicle and a target is known (for example, see Patent Document 1). In such a radar apparatus, first, a radio wave subjected to frequency modulation is transmitted as a transmission signal from the host vehicle. When the target exists within the transmission range of the transmission signal, the transmission signal is reflected by the target and the reflected wave is received by the own vehicle. The radar apparatus generates a beat signal having a frequency difference between a transmission signal and a reception signal. Based on the beat signal, the relative distance and relative speed between the host vehicle and the target are detected.
JP 2003-320866 A

  By the way, in a situation where there are a plurality of vehicles equipped with the above-described millimeter wave radar and each transmits radio waves, there is a possibility that radio waves may interfere with each other. When such radio wave interference occurs, a large frequency fluctuation occurs in the beat signal due to the comparison between the transmission signal and the reception signal, and as a result, the function as the radar apparatus may be impaired.

  Therefore, in order to avoid the occurrence of such radio wave interference, it is conceivable to transmit a transmission signal formed such that the deflection surface is orthogonal to the radio wave emitted by another vehicle facing the host vehicle. However, even if the deflection planes of the transmission signal are orthogonal, there is a component in the right-angle direction, so that the mutual interference of radio waves cannot be suppressed completely. In particular, in a region where millimeter wave radio waves are transmitted from a large number of vehicles such as road intersections, the deflection surfaces of all transmission signals are not always orthogonal, and it is difficult to avoid mutual interference of radio waves.

  The present invention has been made in view of the above-described points, and reliably detects the relative relationship between another vehicle and the host vehicle even when mutual interference with a radio wave that is a transmission signal generated by the other vehicle occurs. It is an object of the present invention to provide an in-vehicle radar device capable of performing the above-mentioned.

  The above object is to cause a first region that emits a frequency-modulated radio wave with a first modulation width and a second region that emits a second modulation width smaller than the first modulation width to appear alternately at a predetermined time period. Transmission signal output means for outputting as a transmission signal, beat signal generation means for generating a beat signal by comparing the transmission signal output by the transmission signal output means and the received signal, and transmission signal output by the transmission signal output means When the fluctuation range of the beat signal generated by the beat signal generation means is larger than a predetermined threshold when the output state is in the second region, interference between the transmission signal of the own vehicle and the transmission signal of the other vehicle If the interference determination means determines that the interference occurs and the interference determination means determines that the interference is occurring, the phase difference between the reception signal in the own vehicle representing the transmission signal of the other vehicle is eliminated. In Transmission timing changing means for changing the transmission timing of the transmission signal of the own vehicle, and reception at the own vehicle representing the transmission signal of the own vehicle and the transmission signal of the other vehicle after the transmission timing is changed by the transmission timing changing means. This is achieved by an in-vehicle radar device that includes a relative distance detection unit that detects a relative distance between the host vehicle and another vehicle based on a phase difference from the signal.

  In the aspect of the invention, the frequency-modulated radio wave appears alternately at a predetermined time period in a first region that emits a relatively large first modulation width and a second region that emits a relatively small second modulation width. Output as a transmission signal. Normally, when a frequency-modulated transmission signal is reflected on a target and the reflected wave is received by the subject vehicle, the subject vehicle and the subject are subjected to beat signals whose frequency difference is the difference between the transmitted signal and the received signal. The frequency fluctuations according to the relative distance between and occur, but the fluctuation range does not become so large. On the other hand, when a transmission signal frequency-modulated from another vehicle is output and received by the host vehicle, the fluctuation range of the beat signal obtained by comparing the transmission signal and the reception signal of the host vehicle is large. May be. Therefore, in the present invention, when the output range of the transmission signal of the own vehicle is in the second region, when the fluctuation range of the beat signal based on the comparison between the transmission signal and the reception signal is larger than a predetermined threshold value, It is determined that there is interference between the transmission signal of the own vehicle and the transmission signal of the other vehicle. And when this determination is made, the transmission timing of the transmission signal of the own vehicle is changed so that the phase difference from the reception signal in the own vehicle representing the transmission signal of the other vehicle is eliminated.

  When the transmission timing is changed in the own vehicle as described above and the transmission signal is transmitted, the transmission signal is received by the other vehicle, and the other vehicle changes the transmission timing as described above to receive the transmission signal. Considering the situation of transmission, it takes time corresponding to the relative distance between the own vehicle and the other vehicle from the transmission of the transmission signal of the own vehicle to the reception of the transmission signal of the other vehicle. A phase difference always occurs. In the present invention, after the transmission timing of the transmission signal is changed, the relative distance between the host vehicle and the other vehicle is detected based on the phase difference. Therefore, according to the present invention, it is possible to reliably detect the relative relationship between the other vehicle and the host vehicle even when mutual interference with a radio wave that is a transmission signal generated by the other vehicle occurs.

  In this case, if a collision prediction unit for predicting a collision between the host vehicle and the other vehicle is provided based on the relative distance detected by the relative distance detection unit, a radio wave that is a transmission signal emitted by the other vehicle and Even when mutual interference occurs, it is possible to accurately predict a collision with another vehicle.

  Further, in the above-described on-vehicle radar device, it is assumed that the vehicle-mounted radar device includes a communication unit that performs information communication with another vehicle using the second region of the transmission signal after the transmission timing is changed by the transmission timing changing unit. Various information such as the vehicle speed of the host vehicle can be provided to the other vehicle, or various information such as the vehicle speed of the other vehicle can be taken into the host vehicle.

  In this case, when a collision between the host vehicle and the other vehicle is predicted by the collision prediction unit, the information on the other vehicle acquired by the information communication by the communication unit is used to avoid the collision or the collision. If the collision prediction control means for executing the collision prediction control is provided so that the impact caused by the vehicle is mitigated, mutual interference with the radio wave that is a transmission signal emitted from the other vehicle occurs and the collision with the other vehicle is predicted. Sometimes, the collision prediction control for avoiding the collision or mitigating the impact caused by the collision can be executed with high accuracy.

  In the above-described on-vehicle radar device, it is preferable that the modulation duration of the first area is shorter than the modulation duration of the second area.

  According to the present invention, it is possible to reliably detect the relative relationship between the other vehicle and the host vehicle even when mutual interference with a radio wave that is a transmission signal emitted by the other vehicle occurs.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of a system including an in-vehicle radar device 10 according to an embodiment of the present invention. As shown in FIG. 1, the on-vehicle radar device 10 of this embodiment includes a radar electronic control unit (hereinafter referred to as a radar ECU) 12 mainly composed of a microcomputer. The radar ECU 12 includes a CPU that performs processing calculation, a ROM that stores a control program, a RAM that temporarily stores data, and an input / output interface.

  A radar antenna 14 is connected to the radar ECU 12. The radar antenna 14 is disposed, for example, in the vicinity of the front grill of the vehicle or inside the front bumper, and includes a transmission antenna 14a that transmits radio waves as a transmission signal, and a reception antenna 14b that receives radio waves as a reception signal. ,have. The radar ECU 12 includes a control unit 16. The control unit 16 controls the transmission signal transmitted from the transmission antenna 14a and executes various controls based on the reception signal received by the reception antenna 14b.

  The radar ECU 12 includes a transmission circuit 20 for transmitting millimeter-wave radio waves toward a predetermined area in front of the vehicle connected to the transmission antenna 14a, and other vehicles and stopping objects in the area connected to the reception antenna 14b. A receiving circuit 30 for receiving a reflected wave reflected from an object target such as a radio wave transmitted from another vehicle.

  The transmission circuit 20 includes a modulation voltage generation circuit 22, a frequency modulation circuit 24, and a directional coupler 26. The modulation voltage generation circuit 22 generates a triangular wave whose amplitude changes in a triangular shape in accordance with a command signal from the control unit 16 of the radar ECU 12, and supplies the triangular wave to the frequency modulation circuit 24. The frequency modulation circuit 24 performs frequency modulation of a carrier wave using the triangular wave supplied from the modulation voltage generation circuit 22 as a modulation signal, and has a predetermined modulation width Δf and a modulation frequency fm (= 1 / T; T as time elapses). A modulation wave signal modulated in the form of a triangular wave is output in accordance with the fluctuation cycle of the triangular wave generated from the modulation voltage generating circuit 22. Further, the directional coupler 26 supplies the modulated wave signal output from the frequency modulation circuit 24 to the transmitting antenna 14a and also to the mixer 32 described later. The transmitting antenna 14a transmits the modulated wave signal supplied from the directional coupler 26 as a transmission signal toward a predetermined area in front of the vehicle.

  The receiving circuit 30 includes a mixer 32, a filter 34, and a fast Fourier transform processing circuit (hereinafter referred to as FFT processing circuit) 36. The reception antenna 14b described above receives a radio wave input from the front of the vehicle as a reception signal. The mixer 32 mixes the received signal received by the receiving antenna 14b and the transmission signal supplied from the directional coupler 26, thereby generating and outputting a beat signal having a frequency difference between the two as a variable frequency. The filter 34 beats the beat signal output from the mixer 32 in a section in which the frequency of the transmission signal rises (rise section) and in a section in which the frequency of the transmission signal falls (down section). Separated into signal. Further, the FFT processing circuit 36 performs FFT processing on each beat signal in the rising section and the falling section, and obtains a power spectrum for the frequency of the beat signal in the rising section and a power spectrum for the frequency of the beat signal in the falling section. calculate. Based on the calculation result of the FFT processing circuit 36, the control unit 16 of the radar ECU 12 calculates and detects the relative distance and relative speed between the host vehicle and the target.

  The system of the present embodiment is connected to the control unit 16 of the radar ECU 12 via a communication line 38, and protects the brake control ECU 40, the engine control ECU 42, the transmission control ECU 44, and the occupant for controlling the running of the vehicle. An air bag control ECU 46 and a seat belt control ECU 48 are provided. The brake control ECU 40 controls the operation of a hydraulic or electric braking brake of the vehicle. The engine control ECU 42 controls driving such as fuel injection and ignition timing of the vehicle. The transmission control ECU 44 controls the shift position of the vehicle transmission. The airbag control ECU 46 controls the operation of the airbag for protecting the vehicle occupant. Further, the seat belt control ECU 48 controls expansion and contraction of the occupant seat belt that can restrain the vehicle occupant appropriately by removing the slack using an electric motor or the like.

  The vehicle running control is not limited to a brake, an engine, and a transmission, and may control a vehicle steering angle using electric power steering. In addition, the occupant protection device is not limited to the airbag or the seat belt as described above, but is a device that moves the vehicle bumper forward of the vehicle body when predicting a collision or a device that returns the vehicle seat to the reference position in order to reduce the impact caused by the collision. There may be.

  The control unit 16 of the radar ECU 12 determines whether or not the possibility that the own vehicle will collide with the target in front of the vehicle is higher than a predetermined value based on the detected relative relationship between the own vehicle and the target (collision). Perform prediction judgment). Note that the higher the relative speed with respect to the target, the higher the possibility of collision, and the shorter the relative distance with respect to the target, the higher the possibility of collision. This may be done by referring to a two-dimensional map with relative distance. The two-dimensional map may be formed by a curve indicating a boundary indicating whether or not the collision can be avoided by the braking brake and a curve indicating a boundary indicating whether or not the collision can be avoided by the vehicle steering. .

  When the control unit 16 of the radar ECU 12 determines that the collision with the target is predicted, the control unit 16 executes the collision prediction control so that the collision is avoided or the impact caused by the collision is reduced. Specifically, for example, the control signal is transmitted to the brake control ECU 40, the engine control ECU 42, or the gear shift so that the vehicle stops fuel injection, performs forced braking brake, or decelerates by performing forced engine braking. The control signal is supplied to the machine control ECU 44, and the control signal is supplied to the airbag control ECU 46 and the seat belt control ECU 48 so that the protection device for the vehicle occupant is activated. When each control ECU 40 to 48 is supplied with a control signal associated with the collision prediction control from the radar ECU 12, each of the control ECUs 40 to 48 operates so that the function of the collision prediction control is exhibited for vehicle deceleration or vehicle occupant protection. Execute.

  The control unit 16 of the radar ECU 12 executes control (vehicle follow-up control) for causing the own vehicle to follow the preceding vehicle, which is the front target, based on the detected relative relationship between the own vehicle and the target. You may do. Specifically, for example, a brake control ECU 40, an engine control ECU 42, or a transmission control ECU 44 outputs a control signal for controlling the vehicle speed so as to follow the preceding vehicle while maintaining a predetermined inter-vehicle distance (which may be in accordance with the vehicle speed). It may be a thing to supply to. In this case, when each control ECU 40 to 44 receives a control signal accompanying the vehicle follow-up control from the radar ECU 12, each control ECU 40 to 44 performs an operation such that the function of the vehicle follow-up control is exhibited.

  Next, a specific operation of the on-vehicle radar device 10 of this embodiment will be described.

  In the on-vehicle radar device 10, a transmission signal that is a radio wave in the millimeter wave band is transmitted from the transmitting antenna 26 toward a predetermined area in front of the vehicle. When a target such as a preceding vehicle or a stop is present in the transmission area of the transmission signal, the transmission signal is reflected by the target and the reflected wave is received by the receiving antenna 30. In this case, the radar ECU 12 generates a beat signal by comparing the transmission signal and the reception signal. The radar ECU 12 detects the relative distance and the relative speed between the host vehicle and the target object by performing the above-described signal processing on the generated beat signal.

  Therefore, according to the on-vehicle radar device 10 of the present embodiment, the transmission signal transmitted from the own vehicle is reflected by the target vehicle such as the preceding vehicle or the stop object existing in the transmission region, and the reflected wave is reflected. When received by the host vehicle, it is possible to appropriately detect the relative distance and relative speed between the host vehicle and its target.

  By the way, when the transmission signal transmitted from the own vehicle is reflected by the target and the reflected wave is received by the own vehicle, the time required from the transmission signal transmission to the reception of the reflected wave is the fluctuation cycle of the transmission signal. Since it is extremely short with respect to T, as shown in FIG. 2, even if the frequency fluctuation according to the relative distance between the subject vehicle and the target occurs with respect to the beat signal having a frequency difference between the transmission signal and the reception signal, The fluctuation range is not so large.

  On the other hand, in a situation where there are a plurality of vehicles equipped with the on-vehicle radar device 10 of the present embodiment on the road and each vehicle transmits a transmission signal from the on-vehicle radar device 10, the transmission signals of other vehicles are When there is another vehicle that reflects on an object or a road, or particularly travels opposite to the host vehicle as shown in FIG. 3, the transmission signal of the other vehicle is directly input, so that mutual interference of radio waves is prevented. May occur. When such radio wave interference occurs, reception of a reception signal transmitted from another vehicle and received by the own vehicle may be greatly shifted in time with respect to transmission of the transmission signal of the own vehicle. A relatively large frequency fluctuation may occur in the beat signal due to the comparison. For this reason, when radio wave interference occurs, it is difficult to accurately detect the relative relationship between the host vehicle and the target with the usual method, and the function as the in-vehicle radar device 10 is impaired. End up.

  Therefore, the on-vehicle radar device 10 of the present embodiment is characterized in that the relative relationship between the other vehicle and the host vehicle is reliably detected even when mutual interference with a radio wave that is a transmission signal generated by the other vehicle occurs. is doing. Hereinafter, the characteristic part of the present embodiment will be described with reference to FIGS. 4 and 5 show the time change of the frequency of the signal transmitted and received by the radar antenna 14 and the time change of the frequency of the beat signal by comparing the transmission signal and the reception signal, respectively. FIG. 6 shows a flowchart of an example of a control routine executed by the control unit 16 in the in-vehicle radar device 10 of the present embodiment.

  In the on-vehicle radar device 10 of the present embodiment, the control unit 16 of the radar ECU 12 first searches for the target object and detects the relative relationship thereof, firstly, sets the modulation width Δf of the frequency-modulated transmission signal to the first A time region having a modulation width Δfr (hereinafter referred to as a radar region) and a time region having a second modulation width Δf2 that is smaller than the first modulation width Δfc (hereinafter referred to as an inter-vehicle cooperation region) are alternately set for a predetermined time. A command signal is supplied to the modulation voltage generation circuit 22 so as to appear in a cycle (step 100). The time Tr for which the radar area lasts is set shorter than the time Tc for which the inter-vehicle cooperation area lasts. Further, the modulation frequency fm in the radar region may be smaller than the modulation frequency fm in the inter-vehicle cooperation region.

  When the transmission signal of the host vehicle is received by the host vehicle as a reflected wave, the time required from transmission of the transmission signal to reception of the reflected wave is extremely short with respect to the fluctuation period T of the transmission signal. The fluctuation amplitude Δw of the beat signal having the frequency difference between the transmission signal and the reception signal as the fluctuation frequency does not become so large in the radar area or the inter-vehicle cooperation area of the transmission signal. On the other hand, when the transmission signal of the other vehicle is received by the own vehicle, that is, when radio wave interference occurs, the transmission of the transmission signal of the own vehicle (shown by a solid line) and the transmission signal of the other vehicle as shown in FIG. A large time lag may occur between the reception by the own vehicle (this reception signal is indicated by a broken line) (phase difference ΔT). Since the time Tr during which the radar region continues is set shorter than the time Tc during which the inter-vehicle cooperation region continues as described above, the frequency fluctuation range of the vehicle-to-vehicle cooperation region of the transmission signal of the host vehicle is relatively smaller than the others. A small beat signal always appears. In this case, the fluctuation amplitude Δwc of the beat signal having a relatively small frequency fluctuation width is the maximum fluctuation amplitude that can be reached when the reception signal is a reflected wave of the transmission signal of the host vehicle, as shown in FIG. It can be larger than that.

  The control unit 16 of the radar ECU 12 controls the fluctuation amplitude Δwc of the beat signal generated by comparing the transmission signal and the received signal when the output state of the transmission signal of the own vehicle is in the inter-vehicle cooperation region where the modulation width Δf is relatively small. By determining whether or not there is a timing that is greater than the predetermined lower threshold and smaller than the predetermined upper threshold, radio wave interference between the transmission signal of the host vehicle and the transmission signal of the other vehicle occurs. It is determined whether or not (step 102). The predetermined lower limit threshold may be the maximum fluctuation amplitude that can be reached by the beat signal when the received signal is a reflected wave of the transmission signal of the host vehicle, and the predetermined upper limit threshold is: The maximum fluctuation amplitude that can be reached by the beat signal generated by the transmission signal having the relatively small modulation width Δfc and the reception signal having the relatively small modulation width Δfc is sufficient (the phase of the transmission signal and the reception signal is 180 ° different). When). As a result of the determination, when the fluctuation amplitude Δwc of the beat signal in the inter-vehicle cooperation region is in the predetermined range, radio wave interference between the transmission signal transmitted from the own vehicle and the transmission signal transmitted from the other vehicle occurs. Is determined.

  When the control unit 16 determines that radio wave interference has occurred in the transmission signal of the own vehicle, first, the fluctuation amplitude Δwc of the beat signal is within the predetermined range from outside the predetermined range in the inter-vehicle cooperation region of the transmission signal. Or the timing of changing from the predetermined range to the outside of the predetermined range is detected, and the phase difference ΔT between the transmission signal of the own vehicle and the reception signal of the own vehicle representing the transmission signal of the other vehicle is detected. Then, as shown in FIG. 4C, the detected phase difference ΔT is eliminated and becomes almost zero, that is, the transmission signal of the own vehicle is almost the same as the reception signal in the own vehicle indicating the transmission signal of the other vehicle. The transmission timing of the transmission signal of the own vehicle is changed so as to synchronize (step 104). When such processing is executed, the fluctuation amplitude Δw of the beat signal becomes extremely small as shown in FIG. Hereinafter, the state in which the phase difference ΔT is small and almost zero is referred to as a synchronous mode.

  In the state where the two vehicles that have caused radio wave interference with each other and are equipped with the on-vehicle radar device 10 of this embodiment are in the synchronous mode, the phase difference ΔT between the transmission signal and the reception signal is set to zero as described above. Even if processing is performed, a phase difference is always generated only for the time when the radio wave travels back and forth between the two vehicles.

  For example, when vehicle A transmits a radio wave that is frequency-modulated as shown in FIG. 5A as a transmission signal, vehicle B transmits the transmission signal from vehicle A according to the relative distance between vehicle A and vehicle B. Reception is delayed by time (specifically, the relative distance divided by the speed of light) (note that the waveform of the received signal is indicated by a broken line in FIG. 5B). When vehicle B receives the transmission signal of vehicle A, vehicle B changes the transmission timing so as to eliminate the phase difference from the reception signal representing the transmission signal of vehicle A, and transmits the radio wave to be frequency-modulated as the transmission signal. (Note that the waveform of the transmission signal is indicated by a solid line in FIG. 5B). In this case, the transmission signal from vehicle B is received by vehicle A with a delay corresponding to the relative distance between vehicle A and vehicle B (specifically, the relative distance divided by the speed of light). (Note that the waveform of the received signal is indicated by a broken line in FIG. 5D). Accordingly, in the synchronous mode, the transmission signal transmitted by the A vehicle (shown by a solid line in FIG. 5D) and the reception signal representing the transmission signal from the B vehicle received by the A vehicle (shown by a wavy line in FIG. 5D). A phase difference is generated only for the time when the radio wave travels back and forth the distance between the A vehicle and the B vehicle.

  That is, conversely, even in a situation where radio wave interference between the transmission signal of the own vehicle and the transmission signal of the other vehicle occurs, the phase difference between the transmission signal and the reception signal that always occurs after the synchronization mode is started. It is possible to detect the relative distance between the two vehicles based on the quantity. In the in-vehicle radar device 10 of the present embodiment, the control unit 16 of the radar ECU 12 determines that radio wave interference with the transmission signal of another vehicle has occurred, and sets the phase difference ΔT between the transmission signal and the reception signal to zero. After starting the synchronous mode to change the transmission timing of the transmission signal, the phase difference between the transmission signal and the reception signal is detected, and based on the phase difference, specifically, the phase difference is multiplied by the speed of light. By dividing the value by “2”, the relative distance between the host vehicle and the other vehicle is calculated (step 106).

  The control unit 16 performs a collision prediction determination based on the relative distance between the host vehicle and the other vehicle calculated using the phase difference between the transmission signal and the reception signal as described above (step 108). As a result, when it is determined that a collision with another vehicle as a target is predicted, first, information such as the vehicle speed and rudder angle of the host vehicle detected by the host vehicle is the target of the collision prediction. In order to notify other vehicles, as shown by the broken line in FIG. 5 (F), a signal representing the information is superimposed in accordance with a predetermined rule in the inter-vehicle cooperation region where the modulation width Δf of the transmission signal is small, and the data signal is superimposed. The transmitted signal is transmitted from the transmission antenna 14a (step 110).

  When the in-vehicle radar device 10 of each vehicle receives a transmission signal in which a data signal such as a vehicle speed is superimposed on the inter-vehicle cooperation region transmitted from the partner vehicle, the in-vehicle radar device 10 uses a beat signal generated based on the received signal. The superimposed data signal is demodulated to obtain information such as the vehicle speed and steering angle of the opponent vehicle. For example, as shown in FIG. 5 (F), when the vehicle-mounted radar device for vehicle A receives a transmission signal in which a data signal such as a vehicle speed is superimposed on the inter-vehicle cooperation region sent from vehicle B, it is based on the received signal. Then, the superimposed data signal is demodulated from the generated beat signal, and information such as the vehicle speed and steering angle of the B vehicle is acquired.

  After determining that a collision with another vehicle such as an oncoming vehicle causing radio wave interference is predicted, the control unit 16 of the radar ECU 12 receives a transmission signal transmitted by the partner vehicle and receives the vehicle speed or rudder of the partner vehicle. When information such as the angle is acquired, the collision prediction control in the own vehicle is performed so that the collision is avoided or the impact caused by the collision is reduced in consideration of the vehicle speed and the steering angle of the other vehicle. Execute (step 112). For example, when the opponent vehicle is steered to the right, the electric power steering device is operated so that a collision is avoided by also steering the host vehicle to the right.

  As described above, in the in-vehicle radar device 10 according to the present embodiment, by setting a radar region having a relatively large modulation width Δf and a vehicle-to-vehicle cooperation region having a relatively small modulation width Δf in a radio wave that is frequency-modulated as a transmission signal. Then, it is determined whether or not there is radio wave interference with the transmission signal of another vehicle equipped with the vehicle-mounted radar device 10 similar to the transmission signal of the own vehicle. Specifically, the frequency fluctuation amplitude of the beat signal having the frequency difference between the transmission signal and the reception signal as the fluctuation frequency in the inter-vehicle cooperation region of the transmission signal is greater than a predetermined lower threshold and the predetermined upper threshold Is smaller than that, it is determined that the radio wave interference has occurred.

  The frequency fluctuation amplitude of the beat signal is not so large when the reception signal is due to the reflected wave of the transmission signal of the own vehicle, but the reception signal is due to the transmission signal transmitted by the other vehicle. The case may be relatively large. Therefore, according to the configuration of the present embodiment described above, it is possible to accurately determine the radio wave interference between the transmission signal of the own vehicle and the transmission signal of the other vehicle.

  Further, in the in-vehicle radar device 10 according to the present embodiment, when it is determined that radio wave interference between the transmission signal of the own vehicle and the transmission signal of the other vehicle occurs, the own vehicle representing the transmission signal of the other vehicle is used. The transmission timing of the transmission signal of the host vehicle is changed so that the phase difference from the received signal is eliminated. However, even if the transmission timing is changed, a phase difference between the two signals is always generated between the two signals only by the time when the radio wave travels back and forth between the host vehicle and the other vehicle. In the present embodiment, after the transmission timing of the transmission signal of the own vehicle is changed as described above, the relative distance between the own vehicle and the other vehicle is detected based on the phase difference between the transmission signal and the reception signal.

  The signal transmitted from the other vehicle and input to the host vehicle is a signal having a higher intensity than the reflected wave input to the host vehicle when the transmission signal of the host vehicle is reflected by the target. For this reason, according to the configuration of the present embodiment described above, it is possible to suppress the occurrence of non-detection of the relative distance as compared to the configuration in which the relative distance between the host vehicle and the other vehicle is detected using the reflected wave. It is possible to improve the accuracy of the detected relative distance. Therefore, according to the in-vehicle radar device of the present embodiment, even when mutual interference of radio waves occurs between the transmission signal of the own vehicle and particularly the transmission signal of another vehicle such as the oncoming vehicle, The relative distance to the vehicle can be detected.

  In this embodiment, when the relative distance between the own vehicle and the other vehicle is detected as described above, the possibility of collision between the own vehicle and the other vehicle is calculated based on the relative distance, and the collision is predicted. The shorter the relative distance, the higher the possibility of collision. For this reason, according to the in-vehicle radar device 10 of this embodiment, even when mutual interference of radio waves occurs between the transmission signal of the own vehicle and particularly the transmission signal of another vehicle such as the oncoming vehicle, It is possible to accurately predict the collision.

  Further, in the in-vehicle radar device 10 of the present embodiment, when the transmission timing of the transmission signal of the own vehicle is changed due to the radio wave interference as described above and a collision between the own vehicle and another vehicle is predicted, Using the inter-vehicle cooperation area of the transmission signal, data communication is performed to notify other vehicles subject to the collision prediction of information such as the vehicle speed and the steering angle of the own vehicle detected by the own vehicle. Specifically, a signal representing detection information in the own vehicle is superimposed on a vehicle-to-vehicle cooperation region in which the modulation width Δf of the transmission signal is small according to a predetermined rule, and the transmission signal on which the data signal is superimposed is transmitted to the transmission antenna 14a. Sent from If such processing is performed by two vehicles each equipped with the on-vehicle radar device 10, both vehicles will exchange vehicle information such as vehicle speed. That is, vehicle information such as the vehicle speed of the host vehicle is provided to another vehicle, and information such as the vehicle speed of the other vehicle is taken into the host vehicle.

  In this embodiment, when data communication for information exchange is performed as described above, the collision is avoided in consideration of the vehicle speed, steering angle, etc. of the opponent vehicle acquired by the data communication, or the impact caused by the collision. The collision predictive control is executed in the host vehicle so that the For this reason, according to the in-vehicle radar device 10 of the present embodiment, even when a mutual interference between a transmission signal emitted from the own vehicle and a transmission signal emitted from another vehicle occurs and a collision with another vehicle is predicted, the other vehicle By acquiring vehicle information such as the vehicle speed of the vehicle and considering its parameters, it becomes possible to accurately execute the collision prediction control of the own vehicle that avoids the collision with other vehicles or alleviates the impact caused by the collision. ing.

  In the above-described embodiment, the radar region in which the modulation width Δf of the frequency-modulated transmission signal is the first modulation width Δfr is the “first region” described in the claims, and the modulation width Δf is The inter-vehicle cooperation region having a second modulation width Δfc smaller than one modulation width Δfr is the “second region” described in the claims, and the predetermined lower threshold for the fluctuation amplitude of the beat signal is The "predetermined threshold value" described in the range is the time Tr in which the radar region continues is the "modulation continuation time in the first region", and the time Tc in which the inter-vehicle cooperation region is continued is the patent This corresponds to the “second region modulation duration” described in the claims.

  In the above-described embodiment, the control unit 16 of the radar ECU 12 has the radar region in which the modulation width Δf is the first modulation width Δfr and the inter-vehicle cooperation region in which the second modulation width Δf2 is smaller than the first modulation width Δfc. Is transmitted from the transmitting antenna 14a as a transmission signal so that the transmission signal and the reception signal are transmitted. By generating a beat signal having a frequency difference as a fluctuation frequency, the “beat signal generating means” described in the claims performs an affirmative determination process in step 102 in the routine shown in FIG. The “interference determination unit” described in the range executes the process of step 104 to perform the “transmission timing changing unit” described in the claims. However, the “relative distance detection means” described in the claims by executing the process of step 106 and the “collision prediction means” described in the claims by executing the process of step 108 By executing the processing of 110, the “communication means” described in the claims is realized.

  By the way, in the above embodiment, a collision with another vehicle is predicted for the vehicle speed, steering angle, etc. of the other vehicle acquired by exchanging information with the other vehicle performed using the inter-vehicle cooperation area of the transmission signal. However, it may be used as a parameter for determining collision prediction together with the relative distance to other vehicles. In such a configuration, since the collision prediction between the host vehicle and the other vehicle is determined based on the relative distance and the communication result (vehicle speed or the like), the collision prediction determination can be accurately performed.

1 is a configuration diagram of a system including an in-vehicle radar device according to an embodiment of the present invention. It is a figure which shows the time change of the frequency of the signal of the signal transmitted / received by a radar antenna, and the time change of the frequency of the beat signal by the comparison with a transmission signal and a received signal. It is the figure showing a mode that two vehicles carrying the vehicle-mounted radar apparatus of a present Example oppose each other. It is a figure which shows the time change of the frequency of the signal of the signal transmitted / received by a radar antenna, and the time change of the frequency of the beat signal by the comparison with a transmission signal and a received signal. It is a figure which shows the time change of the frequency of the signal of the signal transmitted / received by a radar antenna, and the time change of the frequency of the beat signal by the comparison with a transmission signal and a received signal. It is a flowchart of an example of the control routine performed in the vehicle-mounted radar apparatus of a present Example.

Explanation of symbols

10 On-vehicle radar device 12 Radar ECU
14 Radar antenna 16 Control unit

Claims (5)

A first region that emits a frequency-modulated radio wave with a first modulation width and a second region that emits a second modulation width smaller than the first modulation width appear alternately at a predetermined time period and output as a transmission signal A transmission signal output means;
Beat signal generation means for generating a beat signal by comparing the transmission signal output by the transmission signal output means and the reception signal;
If the fluctuation range of the beat signal generated by the beat signal generation means is larger than a predetermined threshold when the output state of the transmission signal by the transmission signal output means is in the second region, the transmission signal of the host vehicle And interference determination means for determining that interference between the transmission signals of other vehicles has occurred,
When the interference determination means determines that the interference has occurred, the transmission timing of the transmission signal of the own vehicle is changed so that the phase difference from the reception signal at the own vehicle representing the transmission signal of the other vehicle is eliminated. Transmission timing changing means for
After the transmission timing is changed by the transmission timing changing means, based on the phase difference between the transmission signal of the own vehicle and the reception signal at the own vehicle representing the transmission signal of the other vehicle, A relative distance detecting means for detecting the distance;
An on-vehicle radar device comprising:   2. The on-vehicle radar device according to claim 1, further comprising a collision prediction unit that predicts a collision between the host vehicle and another vehicle based on the relative distance detected by the relative distance detection unit.   3. The vehicle-mounted vehicle according to claim 1, further comprising a communication unit that performs information communication with another vehicle using the second region of the transmission signal after the transmission timing is changed by the transmission timing changing unit. Radar device.   When a collision between the host vehicle and another vehicle is predicted by the collision prediction means, the information on the other vehicle acquired by information communication by the communication means is used so that the collision is avoided or an impact caused by the collision occurs. 4. The on-vehicle radar device according to claim 3, further comprising a collision prediction control unit that executes collision prediction control so as to be mitigated.   The on-vehicle radar device according to claim 1, wherein the modulation duration of the first region is shorter than the modulation duration of the second region.

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