Method and device for aligning radar of vehicle
A vehicle radar alignment method and device may perform precise alignment of a radar mounted to a vehicle by enhancing the accuracy of determination of the mounting angle of the radar for aligning the radar mounted to the vehicle, in particular, vertical angle estimation, and may enhance the accuracy of vertical angle estimation of the radar mounted to the vehicle even when the vertical beam pattern of the radar is asymmetric to a left and/or right due to a hardware error or mechanical defect in the process of designing the radar.
1 . A method of aligning a radar of a vehicle, the method comprising:
determining a steering vector based on a first reflection signal for a state in which a vertical angle of a test target is aligned at a reference angle;
extracting a first intensity from a second reflection signal for a state in which the vertical angle of the test target is tilted at a predetermined negative angle and a second intensity from a third reflection signal for a state in which the vertical angle of the test target is tilted at a predetermined positive angle, based on the steering vector determined based on the first reflection signal; and
determining a first coefficient based on a first section of a calibration vertical beam pattern, a second coefficient based on a second section of the calibration vertical beam pattern, and a third coefficient based on a third section of the calibration vertical beam pattern, selecting one of the first coefficient, the second coefficient, and the third coefficient based on the first intensity and the second intensity, and estimating a vertical angle of the radar mounted to the vehicle based on the selected one of the first coefficient, the second coefficient, and the third coefficient.
2 . The method of claim 1 , wherein the calibration vertical beam pattern has a left vertical beam pattern and a right vertical beam pattern which are asymmetric with each other with respect to a reference vertical angle of the radar.
3 . The method of claim 2 , wherein a portion of the left vertical beam pattern and a portion of the right vertical beam pattern are set as the second section of the calibration vertical beam pattern according to a preset angular range, a remaining portion of the left vertical beam pattern is set as the first section of the calibration vertical beam pattern, and a remaining portion of the right vertical beam pattern is set as the third section of the calibration vertical beam pattern.
4 . The method of claim 3 , wherein:
the determining of the first coefficient, the second coefficient, and the third coefficient comprises estimating a first quadratic equation for the first section of the calibration vertical beam pattern, a second quadratic equation for the second section of the calibration vertical beam pattern, and a third quadratic equation for the third section of the calibration vertical beam pattern, and
a quadratic term coefficient of the first quadratic equation is determined as the first coefficient, a quadratic term coefficient of the second quadratic equation is determined as the second coefficient, and a quadratic term coefficient of the third quadratic equation is determined as the third coefficient.
5 . The method of claim 1 , wherein, in the selecting one of the first coefficient, the second coefficient, and the third coefficient, the selected one of the first coefficient, the second coefficient, and the third coefficient is selected by comparing a difference between the first intensity and the second intensity with a preset reference value.
6 . The method of claim 5 , wherein the selecting one of of the first coefficient, the second coefficient, and the third coefficient comprises selecting the first coefficient from among the first coefficient, the second coefficient, and the third coefficient when the difference between the first intensity and the second intensity is less than the preset reference value.
7 . The method of claim 5 , wherein the selecting one of the first coefficient, the second coefficient, and the third coefficient comprises selecting the second coefficient from among the first coefficient, the second coefficient, and the third coefficient when an absolute value of the difference between the first intensity and the second intensity is equal to or less than the preset reference value.
8 . The method of claim 5 , wherein the selecting one of the first coefficient, the second coefficient, and the third coefficient comprises selecting the third coefficient from among the first coefficient, the second coefficient, and the third coefficient when the difference between the first intensity and the second intensity is greater than the preset reference value.
9 . The method of claim 1 further comprising:
estimating a horizontal angle of the radar mounted to the vehicle based on the steering vector determined based on the first reflection signal for the state in which the vertical angle of the test target is aligned at the reference angle.
10 . The method of claim 9 , further comprising determining a mounting angle of the radar mounted to the vehicle based on the estimated vertical angle and the estimated horizontal angle of the radar, determining an adjustment angle for a zero point adjustment of the radar based on the determined mounting angle of the radar, and controlling to adjust a position of the radar mounted to the vehicle according to the adjustment angle for the zero point adjustment of the radar.
11 . A device for aligning a radar of a vehicle, the device comprising:
a receiver configured to receive a first reflection signal, a second reflection signal, and a third reflection signal; and
one or more processors configured to:
determine a steering vector based on the first reflection signal for a state in which a vertical angle of a test target is aligned at a reference angle;
extract a first intensity from the second reflection signal for a state in which the vertical angle of the test target is tilted at a predetermined negative angle and a second intensity from the third reflection signal for a state in which the vertical angle of the test target is tilted at a predetermined positive angle, based on the steering vector determined based on the first reflection signal; and
determine a first coefficient based on a first section of a calibration vertical beam pattern, a second coefficient based on a second section of the calibration vertical beam pattern, and a third coefficient based on a third section of the calibration vertical beam pattern, select one of the first coefficient, the second coefficient, and the third coefficient based on the first intensity and the second intensity, and estimate a vertical angle of the radar mounted to the vehicle based on the selected one of the first coefficient, the second coefficient, and the third coefficient.
12 . The device of claim 11 , wherein the calibration vertical beam pattern has a left vertical beam pattern and a right vertical beam pattern which are asymmetric with each other with respect to a reference vertical angle of the radar.
13 . The device of claim 12 , wherein a portion of the left vertical beam pattern and a portion of the right vertical beam pattern are set as the second section of the calibration vertical beam pattern according to a preset angular range, a remaining portion of the left vertical beam pattern is set as the first section of the calibration vertical beam pattern, and a remaining portion of the right vertical beam pattern is set as the third section of the calibration vertical beam pattern.
14 . The device of claim 13 , wherein:
the one or more processors are configured to estimate a first quadratic equation for the first section of the calibration vertical beam pattern, a second quadratic equation for the second section of the calibration vertical beam pattern, and a third quadratic equation for the third section of the calibration vertical beam pattern, and
a quadratic term coefficient of the first quadratic equation is determined as the first coefficient, a quadratic term coefficient of the second quadratic equation is determined as the second coefficient, and a quadratic term coefficient of the third quadratic equation is determined as the third coefficient.
15 . The device of claim 11 , wherein the one or more processors are configured to select one of the first coefficient, the second coefficient, and third coefficient by comparing a difference between the first intensity and the second intensity with a preset reference value.
16 . The device of claim 15 , wherein the one or more processors are configured to select the first coefficient from among the first coefficient, the second coefficient, and the third coefficient when the difference between the first intensity and the second intensity is less than the preset reference value.
17 . The device of claim 15 , wherein the one or more processors are configured to select the second coefficient from among the first coefficient, the second coefficient, and the third coefficient when an absolute value of the difference between the first intensity and the second intensity is equal to or less than the preset reference value.
18 . The device of claim 15 , wherein the one or more processors are configured to select the third coefficient from among the first coefficient, the second coefficient, and the third coefficient when the difference between the first intensity and the second intensity is greater than the preset reference value.
19 . The device of claim 11 , wherein the one or more processors are configured to estimate a horizontal angle of the radar mounted to the vehicle based on the steering vector determined based on the first reflection signal for the state in which the vertical angle of the test target is aligned at the reference angle.
20 . The device of claim 19 , further comprising a controller configured to determine a mounting angle of the radar mounted to the vehicle based on the estimated vertical angle and the estimated horizontal angle of the radar, determine an adjustment angle for a zero point adjustment of the radar based on the determined mounting angle of the radar, and control to adjust a position of the radar mounted to the vehicle according to the adjustment angle for the zero point adjustment of the radar.