Radar device and interference prevention method
In a radar device mounted in a host vehicle, a radar transmitting unit transmits a radar signal; a light detection unit detects ON or OFF of a light of another vehicle in which the radar device is mounted; and a timing control unit sets a transmission timing of the radar signal and a light ON timing of a light of the host vehicle, the light ON timing is synchronized with the transmission timing on basis of detected ON or OFF of the light of the other vehicle. The set transmission timing is different from a transmission timing of a radar signal of the radar device mounted in the other vehicle.
1. A radar device configured to be mounted on a host vehicle and to be used in cooperation with another radar device mounted on another vehicle, the radar device comprising:
a radar transmitter, which, in operation, transmits a radar signal;
a light detector, which, in operation, detects a light state of the another vehicle, the light state of the another vehicle being detected as an ON state if a light of the another vehicle is detected, the light state of the another vehicle being detected as an OFF state if the light of the another vehicle is not detected; and
a controller, which, in operation, sets a transmission state of the radar signal and a light state of the host vehicle based on the detected light state of the another vehicle, wherein
changes in the light state of the host vehicle are synchronized with changes in the transmission state of the radar signal.
2. The radar device according to claim 1 , wherein
the controller sets the light state of the host vehicle to an ON state in a case where the transmission state of the radar signal is set to an ON state, and sets the light state of the host vehicle to an OFF state in a case where the transmission state of the radar signal is set to an OFF state.
3. The radar device according to claim 1 , wherein
the controller sets the light state of the host vehicle to an ON state in a case where the transmission state of the radar signal is set to an OFF state, and sets the light state of the host vehicle to an OFF state in a case where the transmission state of the radar signal is set to an ON state.
4. The radar device according to claim 1 , further comprising:
a radar signal detector, which, in operation, detects the another radar signal transmitted from the other vehicle; and
a determiner, which, in operation, determines whether or not the transmission of the another radar signal, is synchronized with the light state of the another vehicle based on a detection result obtained by the radar signal detector, wherein
the controller sets the transmission state of the radar signal and sets the light state of the host vehicle based on a determination by the determiner.
5. The radar device according to claim 1 , wherein
the controller sets the transmission state of the radar signal to an ON state, at any one of a plurality of periods obtained by dividing an ON/OFF cycle of the light state of the host vehicle by the total number of host and other vehicles.
6. The radar device according to claim 1 , wherein
the controller sets the transmission state of the radar signal to an OFF state in a case where a known light ON/OFF pattern of the light state of the another vehicle is detected by the light detector.
7. The radar device according to claim 1 , wherein
the controller sets the transmission state of the radar signal to an ON state in a case where the controller sets the light state of the host vehicle by using a first light ON/OFF pattern indicative of a request for transmission and the light detector detects a second light ON/OFF pattern from the another vehicle, the second light ON/OFF pattern being indicative of a permission for transmission.
8. The radar device according to claim 7 , wherein
in a case where the light detector detects the first light ON/OFF pattern from the another vehicle, the controller turns on the light state of the host vehicle by using the second light ON/OFF pattern and sets the transmission state of the radar signal to an OFF state for a determined period.
9. The radar device according to claim 7 , wherein
the controller sets the light state of the host vehicle by using the second light ON/OFF pattern in a case where the light detector detects the first light ON/OFF pattern from the another vehicle and does not detect the first light ON/OFF pattern from a vehicle that is different from the host vehicle and the another vehicle.
10. The radar device according to claim 7 , wherein
the controller sets the transmission state of the radar signal to an OFF state for a determined period in a case where the controller does not set the light state of the host vehicle to an ON state by using the first light ON/OFF pattern and where the light detector detects the second light ON/OFF pattern from the another vehicle.
11. The radar device according to claim 7 , wherein
the first light ON/OFF pattern indicates an identification number of a vehicle that requests the request for transmission;
the second light ON/OFF pattern indicates an identification number of a vehicle to be given the permission for transmission; and
the controller sets the transmission state of the radar signal to an ON state in a case where the light detector detects a second light ON/OFF pattern indicating an identification number of the host vehicle from the another vehicle.
12. The radar device according to claim 11 , wherein
the controller turns on the light state of the host vehicle by using the first light ON/OFF pattern after elapse of a random period in a case where the light detector detects a second light ON/OFF pattern not indicating the identification number of the host vehicle from the another vehicle.
13. The radar device according to claim 8 , wherein
each of the first light ON/OFF pattern and the second light ON/OFF pattern indicates a continuation period of transmission; and
the controller sets the transmission state of the radar signal to an OFF state for the continuation period indicated by the first light ON/OFF pattern or second light ON/OFF pattern from the another vehicle.
14. The radar device according to claim 7 , wherein
each of the first light ON/OFF pattern and the second light ON/OFF pattern indicates a continuation period of transmission; and
the controller sets the light state of the host vehicle to an ON state by using the continuation period indicated by the first light ON/OFF pattern from the another vehicle.
15. The radar device according to claim 7 , wherein
the first light ON/OFF pattern indicates an identification number of a vehicle that requests the request for transmission;
a frequency channel used for the transmission and the identification number of the vehicle are associated with each other; and
in a case where frequency channels indicated by first light ON/OFF patterns of a plurality of other vehicles are different from each other, the controller sets the light state of the host vehicle to an ON state for each of the plurality of other vehicles by using the second light ON/OFF pattern.
16. The radar device according to claim 7 , wherein
the first light ON/OFF pattern indicates an identification number of a vehicle that requests the request for transmission;
an interference amount between the another vehicle and the host vehicle and an identification number of the another vehicle are associated with each other; and
the controller sets the light state of the host vehicle to an ON state by using the second light ON/OFF pattern in a case where the interference amount associated with the identification number indicated by the first light ON/OFF pattern from the another vehicle is equal to or larger than a determined threshold value, and the controller sets the light state of the host vehicle to an OFF state by using the second light ON/OFF pattern in a case where the interference amount indicated by the first light ON/OFF pattern of the another vehicle is less than the determined threshold value.
17. The radar device according to claim 7 , wherein
in a situation in which the host vehicle is running at a first speed, the controller sets the transmission state of the radar signal to an ON state in a case where the second light ON/OFF pattern from the another vehicle is detected after the light state of the host vehicle is set by using the first light ON/OFF pattern; and
in a situation in which the host vehicle is running at a second speed that is greater than the first speed, the controller sets the transmission state of the radar signal at a timing different from a transmission period of the another radar signal from the another vehicle that is synchronized with the light state of the another vehicle.
18. The radar device according to claim 1 , wherein
an ON state of the light state of the host vehicle includes a first period in which luminance of a light of the host vehicle is kept and a second period in which the light of the host vehicle is turned on and off in a manner indicating a control signal concerning transmission of the radar signal.
19. The radar device according to claim 1 , further comprising:
an extractor, which, in operation, extracts a color of light emitted by the light of the another vehicle; and
a frequency determiner, which, in operation, determines a frequency channel associated with the extracted color, wherein
the controller sets the transmission state of the radar signal and the light state of the host vehicle in synchronization with the light state of the another vehicle in a case where a frequency channel used by the host vehicle is same as the determined frequency channel, and
the controller sets the transmission state of the radar signal and the light state of the host vehicle independently of the light state of the another vehicle in a case where the frequency channel used by the host vehicle is different from the determined frequency channel.
20. The radar device according to claim 1 , wherein the light state of the another vehicle indicates whether or not there is a transmission of another radar signal from the another radar device, and the transmission state is set to turn on a transmission of the radar signal when the light state of the another vehicle indicates that there is no transmission of another radar signal from the another radar device.
21. An ultrasonic device configured to be mounted on a host vehicle and to be used in cooperation with another ultrasonic device mounted on another vehicle, the ultrasonic device comprising:
an ultrasonic sensor, which, in operation, transmits an ultrasonic wave;
a light detector, which, in operation, detects a light state of the another vehicle, the light state of the another vehicle being detected as an ON state if a light of the another vehicle is detected, the light state of the another vehicle being detected as an OFF state if the light of the another vehicles is not detected; and
a controller, which, in operation sets a transmission state of the ultrasonic wave and a light state of the host vehicle based on the detected light state of the another vehicle, wherein
changes in the light state of the host vehicle are synchronized with changes in the transmission state of the ultrasonic wave.
22. An interference prevention method in a radar device configured to be mounted on a host vehicle and to be used in cooperation with another radar device mounted on another vehicle, the interference prevention method comprising:
detecting a light state of the another vehicle, the light state of the another vehicle being detected as an ON state if a light of the another vehicle is detected, the light state of the another vehicle being detected as an OFF state if the light of the another vehicle is not detected;
setting a transmission state of a radar signal and a light state of the host vehicle based on the detected light state of the another vehicle, wherein
changes in the light state of the host vehicle are synchronized with changes in the transmission state of the radar signal; and
transmitting the radar signal according to the transmission state.