Method and apparatus of determining position of obstacle, and parking assist method and system

1. An apparatus of determining a position of an obstacle, the apparatus comprising:

at least two sensors configured to transmit signals at different positions and receive reflected signals when the transmitting signals are reflected from an obstacle;

an propagation distance calculation unit configured to calculate an propagation distance of a direct signal which is sent from a first sensor which is one of the at least two sensors and received by the first sensor, and an propagation distance of an indirect signal which is sent from a second sensor which is different from the first sensor among the two more sensors and received by the first sensor; and

a position determining unit configured to determine a position of the obstacle by comparing the propagation distance of the direct signal and the propagation distance of the indirect signal, based on a result calculated by the propagation distance calculation unit.

2. The apparatus of claim 1 , wherein the at least two sensors respectively send the signals in a range of a limited solid angle with an intensity equal to or higher than a predetermined level.

3. The apparatus of claim 1 , wherein at least one of a signal sending timing, a signal waveform, a signal frequency, and a kind of signal wave of a signal sent by each of the at least two sensors is set differently from sensor to sensor so that the direct signal and the indirect signal can be discriminated from each other.

4. The apparatus of claim 3 , wherein at least one of the signal waveform, the signal frequency, and the kind of signal wave of the signal sent by each of the at least two sensors is different between two adjacent sensors of which the signal sensing timings are adjacent to each other among the at least two sensors.

5. The apparatus of claim 1 , wherein the propagation distance calculation unit measures intensities of the direct signal and the indirect signal and/or time intervals until the direct signal and the indirect signal are received after being sent to calculate the propagation distance of the direct signal and the propagation distance of the indirect signal.

6. The apparatus of claim 1 , wherein the position determining unit divides the region where the at least two sensors send the signals into two or more areas, and when no indirect signal is received by the first sensor, the position determining unit determines that the obstacle is positioned in an area including a front side of the first sensor among the two or more areas.

7. The apparatus of claim 1 , wherein the position determining unit divides the region where the at least two sensors send the signals into two or more areas,

wherein the position determining unit sets a value obtained by subtracting the propagation distance of the indirect signal from the propagation distance of the direct signal at a boundary between an area including a front side of the first sensor and an area including a front side of the second sensor among the two or more areas as a reference value, and

wherein, when the value obtained by subtracting the propagation distance of the indirect signal from the propagation distance of the direct signal is smaller than the reference value, the position determining unit determines that the obstacle is positioned in the area including the front side of the first sensor, and when the value obtained by subtracting the propagation distance of the indirect signal from the propagation distance of the direct signal is larger than the reference value, the position determining unit determines that the obstacle is positioned in the area including the front side of the second sensor.

8. A parking assist system comprising:

at least two sensors configured to transmit signals at different positions and to receive reflected signals when the transmitting signals are reflected from an obstacle;

an obstacle position determining unit configured to determine a position of the obstacle by comparing an propagation distance of a direct signal which is sent from a first sensor which is one of the at least two sensors and received by the first sensor and an propagation signal of an indirect signal which is sent from a second sensor which is different from the first sensor among the at least two sensors and received by the first sensor; and

an obstacle position display unit configured to divide a region where the at least two sensors send signals into at least two areas and to display an alarm indicating that the obstacle exists in an area including the obstacle position determined by the obstacle position determining unit among the at least two areas.

9. The parking assist system of claim 8 , wherein at least one of a signal sending timing, a signal waveform, a signal frequency, and a kind of signal wave of a signal sent by each of the at least two sensors is set differently from sensor to sensor so that the direct signal and the indirect signal can be discriminated from each other.

10. The parking assist system of claim 8 , wherein the obstacle position determining unit compares intensities of the direct signal and the indirect signal or measures time intervals until the direct signals and the indirect signals are received after being sent so as to compare the propagation distance of the direct signal and the propagation signal of the indirect signal.

11. The parking assist system of claim 8 , wherein, when only the direct signal is received by the first sensor among the direct signal and the indirect signal, the obstacle position determining unit determines that the obstacle is positioned in an area including a front side of the first sensor among the two or more areas.

12. The parking assist system of claim 8 , wherein the obstacle position determining unit sets a value obtained by subtracting the propagation distance of the indirect signal from the propagation distance of the direct signal at a boundary between an area including a front side of the first sensor and an area including a front side of the second sensor among the two or more areas as a reference value, and

wherein, when the value obtained by subtracting the propagation distance of the indirect signal from the propagation distance of the direct signal is smaller than the reference value, the obstacle position determining unit determines that the obstacle is positioned in the area including the front side of the first sensor, and when the value obtained by subtracting the propagation distance of the indirect signal from the propagation distance of the direct signal is larger than the reference value, the obstacle position determining unit determines that the obstacle is positioned in the area including the front side of the second sensor.

13. The parking assist system of claim 8 , wherein the obstacle position display unit displays the alarm in different methods depending on the lengths of the propagation distance of the direct signal and the propagation distance of the indirect signal when displaying the alarm indicating that the obstacle exists in the area including the position of the obstacle.

14. The parking assist system of claim 8 , wherein, when displaying the alarm indicating that the obstacle exists in the area including the position of the obstacle determined by the obstacle position determining unit, the obstacle position display unit displays an alarm for each of the area including the position of the obstacle and the area adjacent to the area including the position of the obstacle among the two or more areas in different methods depending on sizes of the propagation distance of the direct signal and the propagation distance of the indirect signal.

15. A method of determining a position of an obstacle, the method comprising:

sending signals at different positions by at least two sensors and when the signals are reflected from an obstacle, receiving reflected signals by the at least two sensors;

calculating an propagation distance of a direct signal which is sent from a first sensor which is one of the at least two sensors and received by the first sensor, and an propagation distance of an indirect signal which is sent from a second sensor which is different from the first sensor among the at least two sensors and received by the first sensor; and

determining the position of the obstacle by comparing the propagation distance of the direct signal and the propagation distance of the indirect signal, based on a result calculated in the calculating of the propagation distances.