Radar device for vehicle and target determination method therefor
The disclosure relates to a radar device for a vehicle, enabling to determine a target satisfying a pairing condition for finding an intersection point by using a combination of a pair of up-chirp and down-chirp signals with an added down-chirp signal, without an additional hardware resource. The radar device includes at least: a transmission unit configured to transmit, through the transmission antenna, a transmission signal including a pair of up-chirp and down-chirp signals having predetermined slopes, and an added chirp signal having a slope different from the slopes; a reception unit configured to receive, through the reception antenna, a reception signal that is the transmission signal reflected on the target located before the vehicle; and a signal processing unit configured to determine the target satisfying the pairing condition for finding an intersection point through a combination of at least one of a pair of the up-chirp and down-chirp signals.
1. An Frequency-modulated continuous-wave (FMCW)-type radar device for a vehicle, including a transmission antenna and a reception antenna that are installed in a vehicle to detect a target located before the vehicle, the FMCW-type radar device for a vehicle, comprising:
a transmission unit configured to transmit, through the transmission antenna, a transmission signal consisting of, in a continuous sequence, a pair of up-chirp and down-chirp signals having predetermined slopes, and an added down-chirp signal having a slope different from the predetermined slopes;
a reception unit configured to receive, through the reception antenna, a reception signal that is the transmission signal reflected and returning from the target located before the vehicle, wherein the transmission signal is transmitted by the transmission unit; and
a signal processing unit configured to determine, as an actual target, a target satisfying a pairing condition for finding an intersection point through a combination of at least one of a pair of the up-chirp and down-chirp signals acquired using a frequency difference between the transmission signal and the reception signal with the added chirp signal,
wherein a period of the down-chirp signal is configured to be one-half of a period of a pair of the up-chirp and down-chirp signals, and
wherein the signal processing unit comprises:
a determination unit configured to determine whether a sum of the calculated frequency variation according to the distance of the target and the calculated frequency variation according to the velocity of the target is less than zero; and
a target determination unit configured to:
determine, as an actual target, a target satisfying a pairing condition for finding an intersection point at which the down-chirp signal meets the added down-chirp signal when the sum is less than zero; and
determine, as an actual target, a target satisfying a pairing condition for finding an intersection point at which a pair of the up-chirp and down-chirp signals and the added down-chirp signal meet when the sum is equal to or greater than zero, based on the result of the determination by the determination unit.
2. The FMCW-type radar device for a vehicle of claim 1 , wherein the signal processing unit comprises a calculation unit configured to calculate a frequency difference between the transmission signal through the pair of the up-chirp and down-chirp signals and the reception signal, frequency variation according to a distance of the target, and frequency variation according to a velocity of the target.
3. The FMCW-type radar device for a vehicle of claim 1 , wherein, in relation to the added down-chirp signal, a frequency modulation range of a pair of the up-chirp and down-chirp signals is configured to be narrower than a frequency modulation range of the added down-chirp signal.
4. The FMCW-type radar device for a vehicle of claim 1 , wherein the target determination unit is configured to:
measure a distance and a velocity of the target using a frequency difference between the transmission signal through a pair of the up-chirp and down-chirp signals and the reception signal, and a sum of frequency variation according to the distance of the corresponding target and frequency variation according to the velocity of the corresponding target when the sum is less than zero, wherein the frequency variations are calculated through the added down-chirp signal; and measure a distance and a velocity of the target using a frequency difference between the transmission signal through a pair of the up-chirp and down-chirp signals and the reception signal, and a sum of frequency variation according to the distance of the corresponding target and frequency variation according to the velocity of the corresponding target when the sum is equal to or greater than zero.
5. A target determination method for an Frequency-modulated continuous-wave (FMCW)-type radar device for a vehicle, including a transmission antenna and a reception antenna that are installed in a vehicle to detect a target located before the vehicle, the target determination method for a radar device for a vehicle, comprising:
transmitting, through the transmission antenna, a transmission signal consisting of, in a continuous sequence, a pair of up-chirp and down-chirp signals having predetermined slopes, and an added down-chirp signal having a slope different from the predetermined slopes;
receiving, through the reception antenna, a reception signal that is the transmission signal reflected and returning from the target located before the vehicle, wherein the transmission signal is transmitted by the transmission unit; and
determining, as an actual target, a target satisfying a pairing condition for finding an intersection point through a combination of at least one of a pair of the up-chirp and down-chirp signals acquired using a frequency difference between the transmitted transmission signal and the received reception signal with the added chirp signal,
wherein a period of the down-chirp signal is configured to be one-half of a period of a pair of the up-chirp and down-chirp signals, and
wherein determining the target as an actual target comprises:
determining whether a sum of frequency variation according to the distance of the target and frequency variation according to the velocity of the target is less than zero, wherein the frequency variations are calculated through a pair of the up-chirp and down-chirp signals; and
determining, as an actual target, a target satisfying a pairing condition for finding an intersection point at which the down-chirp signal meets the added down-chirp signal when the sum is less than zero, and determining, as an actual target, a target satisfying a pairing condition for finding an intersection point at which a pair of the up-chirp and down-chirp signals and the added down-chirp signal meet when the sum is greater than zero, based on the result of determining whether the sum is less than zero.
6. The target determination method of claim 5 , wherein, in relation to the added down-chirp signal, a frequency modulation range of a pair of the up-chirp and down-chirp signals is configured to be narrower than a frequency modulation range of the added down-chirp signal.
7. The target determination method of claim 5 , wherein determining the target as an actual target comprises:
measuring a distance and a velocity of the target using a frequency difference between the transmission signal through a pair of the up-chirp and down-chirp signals and the reception signal, and a sum of frequency variation according to the distance of the corresponding target and frequency variation according to the velocity of the corresponding target when the sum is less than zero, wherein the frequency variations are calculated through the added down-chirp signal; and
measuring a distance and a velocity of the target using a frequency difference between the transmission signal through a pair of the up-chirp and down-chirp signals and the reception signal, and a sum of frequency variation according to the distance of the corresponding target and frequency variation according to the velocity of the corresponding target when the sum is equal to or greater than zero.