Radar system and speed correction method thereof

Abstract

The invention discloses a radar system and a speed correction method thereof. The radar system comprises a plurality of radio frequency circuits and a processing circuit. The radio frequency circuit is used for acquiring a plurality of radio frequency signals about an object; the processing circuit is used for measuring the distance and the angle of the object relative to the radar system according to the radio frequency signal in each of a plurality of periods, and calculating coordinates according to the distance and the angle; the processing circuitry is also configured to obtain a plurality of combinations between the cycles, wherein each combination corresponds to two cycles; for each combination, the processing circuit calculates the speed according to the corresponding coordinates and the period difference; the processing circuit is used for calculating the statistical values of the speeds corresponding to the combinations and calculating the corrected speed according to the statistical values. According to the radar system and the speed correction method provided by the invention, the corrected speed is generated by setting a plurality of combinations, so that the measurement error can be eliminated, and the relatively accurate and stable speed can be generated.

Description

Technical Field

[0001] The present invention relates to a radar system, and more particularly to a method for correcting the speed of a radar system. Accurate speed can be calculated through multiple statistical values of permutations and combinations. Background Art

[0002] A radar is a system that uses radio waves to detect the distance, speed, and angle of an object. When performing distance measurement, the radar system emits a beam of radio waves from the antenna. When these radio waves encounter a target object, part of the waves are reflected back to the radar system. The radar system calculates the distance based on the time required for the radio waves to be emitted and returned. Speed calculation relies on the Doppler Effect. The radar system calculates the frequency difference between the transmitted and received radio waves, and uses the frequency difference and the transmitted wave frequency to calculate the speed of the object. The radar system can also be configured with a directional antenna, and the angle of the target object relative to the radar can be calculated based on the direction of the returned wave. However, when the angle between the target object and the radar system is within a specific range, it will cause inaccurate speed measurement. How to solve this problem is an issue of concern to those skilled in the art.

[0003] Therefore, it is necessary to provide a radar system and its speed correction method to solve the above problems. Summary of the Invention

[0004] An embodiment of the present invention provides a radar system, including a plurality of radio frequency circuits and a processing circuit. The radio frequency circuits are used to obtain a plurality of radio frequency signals about an object. The processing circuit is electrically connected to the radio frequency circuits and is used to measure the distance and angle of the object relative to the radar system according to the radio frequency signals in each of a plurality of periods, and calculate at least one coordinate according to the distance and angle. The processing circuit is used to obtain a plurality of combinations between the periods, where each combination corresponds to two periods. For each combination, the processing circuit calculates at least one speed according to the corresponding coordinates and the period difference. The processing circuit is used to calculate at least one statistical value of the speeds corresponding to these combinations, and calculate the corrected speed according to the statistical value.

[0005] In some embodiments, the above coordinates include a first coordinate and a second coordinate, and the processing circuit calculates the first coordinate and the second coordinate according to the following mathematical formulas.

[0006] x i =R i ·cos(θ i )

[0007] y i =R i ·sin(θ i )

[0008] Where R iThe distance measured in the i-th cycle of the period, θ i The angle measured in the i-th cycle, x i The first coordinate calculated in the i-th cycle, y i The second coordinate calculated in the i-th cycle, where i is a positive integer.

[0009] In some embodiments, the above-mentioned speed includes a first speed and a second speed, and the k-th combination in the above combination corresponds to the i-th cycle and the j-th cycle. The processing circuit is used to calculate the first speed and the second speed according to the following mathematical formula.

[0010]

[0011]

[0012] Where v x,k Is the first speed of the k-th combination, v y,k Is the second speed of the k-th combination, ΔT is the length of one cycle time, and k is a positive integer.

[0013] In some embodiments, the processing circuit is further used to determine whether the number of cycles is greater than a cycle count value. If not, it processes the next cycle. If so, it stops processing the next cycle.

[0014] In some embodiments, the processing circuit is further used to determine whether the corresponding distance in one of the cycles is greater than a distance threshold value. If so, it sets the cycle count value to a first value, otherwise it sets the cycle count value to a second value, where the first value is greater than the second value.

[0015] In some embodiments, the processing circuit is used to determine whether the difference between the corresponding first speeds in n consecutive cycles is less than a speed threshold value and whether the difference between the corresponding second speeds is less than the speed threshold value. If so, it stops processing the next cycle. Otherwise, it processes the next cycle, where n is a positive integer greater than 1.

[0016] In some embodiments, the above-mentioned statistical value includes the average value and the standard deviation of the speeds corresponding to the combinations. The processing circuit is used to set a clustering range according to the average value and the standard deviation, divide the speeds within the clustering range into multiple bins, and determine the corrected speed according to the bin with the most repetitions.

[0017] In some embodiments, the processing circuit is used to set the clustering range to be between the average value minus the standard deviation and the average value plus the standard deviation.

[0018] In some embodiments, the processing circuit is used to set the middle value of the bin with the most repetitions as the corrected speed.

[0019] In some embodiments, the processing circuit is configured to execute a clustering algorithm, an association algorithm, or a tracking algorithm according to the corrected speed.

[0020] From another perspective, embodiments of the present invention propose a method for speed correction of a radar system, which is executed by a processing circuit. The speed correction method includes: obtaining a plurality of radio frequency signals regarding an object through a plurality of radio frequency circuits; in each of a plurality of periods, measuring the distance and angle of the object relative to the radar system according to the radio frequency signals, and calculating at least one coordinate according to the distance and angle; obtaining a plurality of combinations between the periods, where each combination corresponds to two periods; for each combination, the processing circuit calculates at least one speed according to the corresponding coordinates and the period difference; and calculating at least one statistical value of the speeds corresponding to the combinations, and calculating a corrected speed according to the statistical value.

[0021] In the radar system and the speed correction method proposed by the present invention, by setting a plurality of combinations and then generating a corrected speed, measurement errors can be eliminated and a more accurate and stable speed can be generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To make the above features and advantages of the present invention more obvious and understandable, the following specific embodiments are given and described in detail in conjunction with the accompanying drawings.

[0023] Figure 1 FIG. is a schematic diagram of a radar system according to an embodiment.

[0024] Figure 2 FIG. is a flowchart of a speed correction method according to an embodiment.

[0025] Figure 3 FIG. is a schematic diagram of a coordinate system of a radar system according to an embodiment.

[0026] Figures 4 to 6 FIG. is a data chart for calculating a corrected speed according to an embodiment.

[0027] Figures 7A to 7F FIG. is a chart showing experimental results according to an embodiment.

[0028] Figure 8A AND Figure 8B FIG. is a flowchart of a speed correction method according to another embodiment.

[0029] MAIN COMPONENT SYMBOL DESCRIPTION:

[0030] 100 Radar system

[0031] 111-113 Antenna

[0032] 121-123 Radio frequency front end

[0033] 131 and 132 Analog-to-digital converters

[0034] 141 to 143 Radio frequency circuits

[0035] 150 Processing circuit

[0036] 160 Object

[0037] 201 to 206 Steps 300 Coordinate system

[0038] R Distance

[0039] θ Angle

[0040] 400, 500, 600, 700, 730, 740, 750, 760, 770 Charts

[0041] 410 Coordinate points

[0042] 601 to 603 Slots

[0043] 701 and 751 Marks

[0044] 710, 720, 752, 753 Trajectories

[0045] 731, 741, 761, 771 Red circles

[0046] 732, 742, 762, 772 Black circles

[0047] 801 to 826 Steps Detailed implementation manners

[0048] Regarding the "first", "second", etc. used herein, they do not particularly refer to the order or sequence, but are only used to distinguish elements or operations described with the same technical terms.

[0049] Figure 1 is a schematic diagram showing a radar system according to an embodiment. Please refer to Figure 1 , the radar system 100 includes antennas 111 to 113, radio frequency circuits 141 to 143, and a processing circuit 150. The radio frequency circuits 141 to 143 are electrically connected to the antennas 111 to 113 respectively, and the processing circuit 150 is electrically connected to the radio frequency circuits 141 to 143. The radar system 100 can be disposed on a vehicle or any device to measure the speed of an object 160.

[0050] Antennas 111 to 113 are used to transmit and receive radio waves. The radio frequency circuit 141 includes the radio frequency front end 121, the radio frequency circuit 142 includes the radio frequency front end 122 and the analog-to-digital converter 131, and the radio frequency circuit 143 includes the radio frequency front end 123 and the analog-to-digital converter 132. In this embodiment, the radio frequency front end 121 is electrically connected to the processing circuit 150; the analog-to-digital converter 131 is electrically connected between the radio frequency front end 122 and the processing circuit 150; the analog-to-digital converter 132 is electrically connected between the radio frequency front end 123 and the processing circuit 150. The radio frequency front ends 121 to 123 are respectively electrically connected to the antennas 111 to 113 to amplify, frequency-convert, demodulate, filter, etc. the signals received by the antennas. In addition to the analog-to-digital converters 131 to 132, the radio frequency circuits 141 to 143 may also include power amplifiers, mixers, filters, etc. Through the operation of these components, the radio frequency circuits 141 to 143 can generate radio frequency signals, and these radio frequency signals contain information such as the distance and angle of the object 160. The processing circuit 150 is used to execute a speed correction method, and this method will be described in detail below.

[0051] Figure 2 is a flowchart showing the speed correction method according to an embodiment. Please refer to Figure 2 , and multiple cycles are set here. Each cycle is, for example, 50 microseconds, but the present invention is not limited thereto. Steps 201 to 203 are executed in each cycle. In step 201, according to the above-mentioned radio frequency signals, the distance (hereinafter denoted as R) and angle (hereinafter denoted as θ) of the object 160 relative to the radar system 100 are measured, and at least one coordinate is calculated based on this distance and angle. Please refer to Figure 3 , the coordinate system 300 of the radar system 100 includes the X coordinate and the Y coordinate, where the coordinate (0, 0) represents the position of the radar system 100. The object 160 has a distance R and an angle θ relative to the radar system 100. In this embodiment, the x coordinate and the y coordinate will be calculated, as shown in the following mathematical formula 1.

[0052] [Mathematical formula 1]

[0053] x i = R i ·cos(θ i )

[0054] y i = R i ·sin(θ i )

[0055] where R i represents the distance measured in the i-th cycle. θ i represents the angle measured in the i-th cycle. x irepresents the X coordinate (also known as the first coordinate) calculated in the i-th cycle, y i represents the Y coordinate (also known as the second coordinate) calculated in the i-th cycle. i is a positive integer.

[0056] Please refer to Figure 2 , and then proceed to step 202 to obtain multiple combinations between multiple cycles, where each combination corresponds to two cycles. If 10 cycles have passed, a total of combinations will be obtained; if 15 cycles have passed, a total of combinations will be obtained. In other words, all permutations and combinations of any two cycles within multiple cycles are to be obtained here. In addition, for each combination, the speed on the X-axis (also known as the first speed) and the speed on the Y-axis (also known as the second speed) will be calculated based on the corresponding coordinates and the cycle difference. Assume that the k-th combination corresponds to the i-th cycle and the j-th cycle, where i > j, and k, j are positive integers. The calculation of the X-axis speed and the Y-axis speed is shown in the following mathematical formula 2.

[0057] [Mathematical formula 2]

[0058]

[0059]

[0060] where v x,k is the X-axis speed of the k-th combination, and v y,k is the Y-axis speed of the k-th combination. ΔT is the cycle time length, for example, 50 microseconds, and (i - j) is the above-mentioned cycle difference. For example, if there are a total of 4 cycles, there are combinations, and the X-axis speeds of these 6 combinations are shown in the following mathematical formula 3.

[0061] [Mathematical formula 3]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068] Next, in step 203, it is determined whether there are n consecutive (less variable) cycles or whether the number of processed cycles is greater than a cycle count value, where n is a positive integer. If the answer is no, then step 204 is performed to process the next cycle; if the answer is yes, steps 205-206 are performed.

[0069] Specifically, the above cycle count value is a constant, and in some embodiments, this cycle count value can be set in the first cycle. When the distance R1 is greater than a distance critical value (for example, 70 meters), the cycle count value is set to a first value; otherwise, the cycle count value is set to a second value, where the first value is greater than the second value. For example, the first value can be 15 and the second value can be 10, but the present invention is not limited thereto. When the distance R1 is large, there is a large error in the measured speed. Therefore, setting a larger cycle count value can reduce the error, but this will result in a corrected speed at a later time. Therefore, when the distance R1 is small, a smaller cycle count value is set to correct the speed faster. If the number of currently processed cycles has not exceeded the cycle count value, the next cycle is processed (step 204); if the number of cycles has exceeded the cycle count value, step 205 is performed.

[0070] On the other hand, in the above step of determining whether there are n consecutive cycles, when the number of cycles is not greater than the cycle count value, it is determined whether the difference between the corresponding X-axis speeds in n consecutive cycles is less than a speed critical value and whether the difference between the corresponding Y-axis speeds is less than the speed critical value. Here, n is a positive integer greater than 1. For example, when the positive integer n is equal to 4, 4 X-axis speeds can be obtained from the above combination, which are v x，k 、v x，k-1 、v x，k-2 、v x，k-3 , and in addition, 4 Y-axis speeds are also obtained, which are v y，k 、v y，k-1 、v y，k-2 、v y，k-3 . Then, it is determined whether the following mathematical formula 4 holds.

[0071] [Mathematical formula 4]

[0072] |v x，k -v x，k-1 |<V T and |v x，k-1 -v x，k-2 |<V T and |v x，k-2 -v x，k-3 |<V T

[0073] and |v y，k -v y，k-1 |<V Tand |v y，k-1 -v y，k-2 | < V T and |v y，k-2 -v y，k-3 | < V T

[0074] where k is a suitable positive integer, and in this example k ≥ 4. V T is the speed critical value, for example, 1 m / s. In other embodiments, any n speeds can be selected from the above combinations for judgment, and the present invention is not limited to Mathematical Formula 4. If Mathematical Formula 4 does not hold, it means that the speed differences calculated in different periods are very large, and more periods need to be measured, so step 204 is performed. If Mathematical Formula 4 holds, it means that the calculated speed has tended to be stable, then the processing of the next period is stopped, and steps 205 - 206 are performed.

[0075] In step 205, at least one statistical value of the speeds (including the X-axis speed and the Y-axis speed) corresponding to the above combination is calculated. In this embodiment, these statistical values include the average value and the standard deviation.

[0076] In step 206, the corrected speed is calculated according to the statistical value. In this embodiment, a clustering range is set first according to the average value and the standard deviation. For example, the average value of the X-axis speed can be expressed as mean vx , and the standard deviation is expressed as std vx , and the above clustering range is between (mean vx -m × std vx ) and (mean vx +m × std vx ), where m is a positive integer. When m = 1, the clustering range is between the average value minus the standard deviation and the average value plus the standard deviation. Next, the speeds v x，k within the clustering range are divided into multiple bins, and the corrected speed is determined according to the bin with the most repetitions among these bins. Similar processing is performed for the Y-axis speed. The average value of the Y-axis speed can be expressed as mean vv , and the standard deviation is expressed as std vy , and the corresponding clustering range is between (mean vy -m × std vy ) and (mean vy +m × std vy ).

[0077] Figures 4 to 6 is a data chart showing the calculation of the corrected speed according to an embodiment. Please refer to Figure 4, the horizontal axis of the graph 400 is the Y-axis distance, and the vertical axis is the X-axis distance. The coordinate point 410 represents the position of the detected object, and the number next to the coordinate point 410 represents the number of the cycle. For example, the position of the detected object in the first cycle is approximately at the coordinate point 410 of (x = 23.9, y = 2.9), and the position of the detected object in the second cycle is approximately at the coordinate point 410 of (x = 23.91, y = 2.15). It can be seen from Figure 4 that the positions of the detected objects in the first 10 cycles are very scattered, which has many errors.

[0078] After Figure 2 the operations of steps 201 to 204 in, multiple combinations and corresponding speeds can be obtained. Taking the X speed as an example, these speeds are plotted in Figure 5 the graph 500 of, where the horizontal axis is the X speed and the vertical axis is the number of combinations. In the example of Figure 5 , most of the speeds are distributed between -3 and 0. After Figure 2 the operation of step 205 in, the average value of these speeds is -1.5952 m / s, and the standard deviation is 0.9539 m / s. In this embodiment, the clustering range is set between (-1.5952 - 0.9539) and (-1.5953 + 0.9539). Next, the speeds within this clustering range are taken and divided into multiple bins. Please refer to Figure 6 the graph 600 of, where the horizontal axis is the X-axis speed and the vertical axis is the number of combinations (which also represents the repetition times of the bins). Here, the width of the bin is preset, for example, 0.2. For simplicity, only three bins 601 to 603 are shown here. The repetition times of bin 601 is 11, the repetition times of bin 602 is 8, and the repetition times of bin 603 is 3. Therefore, bin 601 has the largest repetition times. Next, the median value of bin 601 (i.e., -1.8) can be taken as the corrected speed.

[0079] Figures 4 to 6 Taking the X speed as an example for illustration, the Y speed can be processed according to the same process, which will not be repeated here. After calculating the corrected speed, the processing circuit 150 can execute a clustering algorithm, a correlation algorithm, or a tracking algorithm according to this corrected speed. The clustering algorithm is to cluster the speeds to distinguish different objects. The correlation algorithm is to correlate the speed calculated in the current cycle with the speed in the previous cycle. The tracking algorithm is to track the trajectory of an object. However, in other embodiments, the processing circuit 150 can also execute other suitable algorithms according to these corrected speeds, and the present invention is not limited thereto. Please refer back to Figure 2 , after calculating the corrected speed, it can return to step 204, enter the next cycle, and return to step 201.

[0080] Figures 7A to 7FIt is a graph showing experimental results according to an embodiment. Please refer to Figure 7A , the horizontal axis of graph 700 represents the Y-axis distance, and the vertical axis represents the X-axis distance. Marker 701 represents the position of radar system 100. In this experiment, the experimental object moved linearly from the position (x = 10, y = 70) to the position (x = 10, y = -10). The positions measured by the radar system are plotted as blue circles. It can be seen that the positions of the blue circles are very scattered in the first few cycles, with many errors. If the tracking algorithm is executed without performing velocity correction, the obtained trajectory is 710, which consists of red circles. After executing the above velocity correction method and then executing the tracking algorithm, the obtained trajectory is 720, which consists of black circles. From Figure 7A , it can be seen that trajectory 720 will be delayed by several cycles because it is necessary to wait for several cycles to calculate multiple combinations. In addition, compared with trajectory 710, trajectory 720 is more stable and more in line with the linear motion from (x = 10, y = 70) to (x = 10, y = -10). Refer to Figure 7A and Figure 7B , the horizontal axis of graph 730 represents the cycle, and the vertical axis represents the X-axis velocity. The red circle 731 is the estimated X velocity of trajectory 710. The black circle 732 is the corrected X velocity of trajectory 720. Refer to Figure 7A and Figure 7C , the horizontal axis of graph 740 represents the cycle, and the vertical axis represents the Y-axis velocity. The red circle 741 is the estimated Y velocity of trajectory 710. The black circle 742 is the corrected Y velocity of trajectory 720. From Figure 7B and Figure 7C , it can be seen that the corrected black circles 732 and black circles 742 are more stable and more in line with the linear motion from (x = 10, y = 70) to (x = 10, y = -10).

[0081] Refer to Figure 7D , the horizontal axis of graph 750 represents the Y-axis coordinate, and the vertical axis represents the X-axis coordinate. Marker 751 represents the position of radar system 100. In this experiment, the experimental object moved slowly upward from below and passed marker 751 at y = -2m. The Y-axis velocity of the experimental object is approximately equal to 0, and the X-axis velocity is a certain specific value to pass marker 751. If the tracking algorithm is executed without performing velocity correction, a trajectory 752 consisting of red circles will be generated. After executing the above velocity correction method and then executing the tracking algorithm, a trajectory 753 consisting of black circles will be generated. Without correction, the experimental object on trajectory 752 seems to move inward and looks like it will collide with marker 751. However, trajectory 753 can provide correct information to detect whether a collision occurs. Refer to Figure 7D and Figure 7E, the horizontal axis of Chart 760 represents the period, and the vertical axis represents the X-axis speed. The red circle 761 is the estimated X speed of the trajectory 752. The black circle 762 is the corrected X speed of the trajectory 753. Refer to Figure 7D and Figure 7F , the horizontal axis of Chart 770 represents the period, and the vertical axis represents the Y-axis speed. The red circle 771 is the estimated Y speed of the trajectory 752. The black circle 772 is the corrected Y speed of the trajectory 753. From Figure 7E and Figure 7F , it can be seen that the corrected black circles 762 and 772 are more stable and more in line with the linear motion that surpasses the mark 751 from below.

[0082] Figure 8A With Figure 8B is a flowchart showing the speed correction method according to another embodiment. Please refer to Figure 8A , in step 801, first set the period time length ΔT and the speed threshold V T . In step 802, initialize the positive integers i and j, both are set to 1. In step 803, measure the distance r and the angle θ. In step 804, calculate the X coordinate and the Y coordinate. In step 805, store the X coordinate and the Y coordinate in a memory (not shown). In step 806, determine whether the positive integer i is greater than 1, where i represents the number of the cycle. If the positive integer i is equal to 1, in step 807, determine whether the distance r is greater than 70 meters. If the distance r is greater than 70 meters, in step 809, set the cycle count value (CYCLE_CNT) to 15, otherwise in step 808, set the cycle count value to 10, and then return to step 803 to process the next cycle.

[0083] If the positive integer i is greater than 1, in step 810, set the positive integer j equal to 1. In step 811, calculate the X-axis speed and the Y-axis speed according to the above mathematical formula 2. In step 812, add 1 to the positive integer j. In step 813, determine whether the positive integer j is equal to the positive integer i. If not, it means that not all combinations have been processed. In step 816, add 1 to the positive integer k and return to step 811. If the positive integer j is equal to the positive integer i, in step 814, add 1 to the positive integer i. In step 815, determine whether the positive integer i is greater than the positive integer n. If the positive integer i is not greater than the positive integer n, in step 817, determine whether the positive integer i is greater than or equal to the cycle count value. If the positive integer i is not greater than or equal to the cycle count value, process the next cycle and return to step 803. If the positive integer i is greater than or equal to the cycle count value, end Figure 8A the process. On the other hand, if the judgment result in step 815 is yes, in step 818, determine whether there are n consecutive cycles with relatively small changes as described above. If yes, end Figure 8A the process, otherwise return to step 816.

[0084] Please refer to Figure 8B , in step 819, calculate the average value of the X-axis speed. In step 820, calculate the average value of the Y-axis speed. In step 821, calculate the standard deviation of the X-axis speed. In step 822, calculate the standard deviation of the Y-axis speed. In step 823, divide the X-axis speeds within the clustering range into three bins. In step 824, determine the corrected speed based on the bin with the most repetitions. In step 825, divide the Y-axis speeds within the clustering range into three bins. In step 826, determine the corrected speed based on the bin with the most repetitions.

[0085] In the above-mentioned proposed radar system and speed correction method, by setting multiple combinations and then generating the corrected speed, measurement errors can be eliminated and a more accurate and stable speed can be generated.

[0086] Although the present invention has been disclosed above in embodiments, it is not intended to limit the present invention. Any person of ordinary skill in the art should be able to make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the scope of the appended claims.

Claims

1. A radar system, the radar system comprising: a plurality of radio frequency circuits for obtaining a plurality of radio frequency signals regarding an object; and a processing circuit electrically connected to the radio frequency circuits for measuring, in each of a plurality of cycles, a distance and an angle of the object relative to the radar system based on the radio frequency signals, and calculating at least one coordinate based on the distance and the angle, wherein the processing circuit is configured to obtain a plurality of combinations between the cycles, each of the combinations corresponding to two of the cycles, wherein for each of the combinations, the processing circuit calculates at least one velocity based on the corresponding at least one coordinate and a cycle difference, wherein the processing circuit is configured to calculate at least one statistical value of the velocities corresponding to the combinations, and calculate a corrected velocity based on the at least one statistical value.

2. The radar system according to claim 1, wherein the at least one coordinate includes a first coordinate and a second coordinate, and the processing circuit calculates the first coordinate and the second coordinate according to the following mathematical formula: x i = R i · cos(θ i ) y i = R i ·sin(θ i ) where R i is the distance measured in the i-th cycle among these cycles, θ i is the angle measured in the i-th cycle, x i is the first coordinate calculated in the i-th cycle, y i is the second coordinate calculated in the i-th cycle, and i is a positive integer.

3. The radar system according to claim 2, wherein the at least one velocity includes a first velocity and a second velocity, the k-th combination among the combinations corresponds to the i-th cycle and the j-th cycle, and the processing circuit is configured to calculate the first velocity and the second velocity according to the following mathematical formula: where v x,k is the first speed of the k-th combination, v y,k is the second speed of the k-th combination, ΔT is a cycle time length, and k is a positive integer.

4. The radar system according to claim 3, wherein the processing circuit is further configured to determine whether the number of the cycles is greater than a cycle count value. If not, process the next cycle. If so, stop processing the next cycle.

5. The radar system according to claim 4, wherein the processing circuit is further configured to determine, in one of the cycles, whether the corresponding distance is greater than a distance threshold value. If so, set the cycle count value to a first value. Otherwise, set the cycle count value to a second value, where the first value is greater than the second value.

6. The radar system according to claim 3, wherein the processing circuit is configured to determine whether a difference between the corresponding first velocities in consecutive n cycles is less than a velocity threshold value and whether a difference between the corresponding second velocities is less than the velocity threshold value. If so, stop processing the next cycle. Otherwise, process the next cycle, where n is a positive integer greater than 1.

7. The radar system according to claim 1, wherein the at least one statistical value includes an average value and a standard deviation of the velocities corresponding to the combinations, wherein the processing circuit is configured to set a clustering range based on the average value and the standard deviation, divide the velocities within the clustering range into a plurality of bins, and determine the corrected velocity based on the bin that repeats the most times among the bins.

8. The radar system according to claim 7, wherein the processing circuit is configured to set the clustering range to be between the average value minus the standard deviation and the average value plus the standard deviation.

9. The radar system according to claim 7, wherein the processing circuit is configured to set the median value of the bin that repeats the most times as the corrected velocity.

10. The radar system as claimed in claim 1, wherein the processing circuit is configured to perform a clustering algorithm, a correlation algorithm or a tracking algorithm according to the corrected speed.

11. A method for speed correction of a radar system, the speed correction method being executed by a processing circuit, the speed correction method comprising: Obtaining, by a plurality of radio frequency circuits, a plurality of radio frequency signals regarding an object; In each of a plurality of cycles, measuring, according to the radio frequency signals, a distance and an angle of the object relative to the radar system, and calculating at least one coordinate according to the distance and the angle; Obtaining a plurality of combinations between the cycles, wherein each of the combinations corresponds to two of the cycles; For each of the combinations, the processing circuit calculating at least one speed according to the corresponding at least one coordinate and a cycle difference; and Calculating at least one statistical value of the speeds corresponding to the combinations, and calculating a corrected speed according to the at least one statistical value.

12. The speed correction method as claimed in claim 11, wherein the at least one coordinate includes a first coordinate and a second coordinate, and the step of calculating the at least one coordinate includes: Calculating the first coordinate and the second coordinate according to the following mathematical formula x i = R i ·cos(θ i ) y i = R i ·sin(θ i ) where R i is the distance measured in the i-th cycle of these cycles, θ i is the angle measured in the i-th cycle, x i is the first coordinate calculated in the i-th cycle, y i is the second coordinate calculated in the i-th cycle, and i is a positive integer.

13. The speed correction method as claimed in claim 12, wherein the at least one speed includes a first speed and a second speed, and the k-th combination among the combinations corresponds to the i-th cycle and the j-th cycle, and the step of calculating the at least one speed includes: Calculating the first speed and the second speed according to the following mathematical formula where v x,k is the first speed of the k-th combination, v y,k is the second speed of the k-th combination, ΔT is a cycle time length, and k is a positive integer.

14. The speed correction method as claimed in claim 13, wherein before the step of calculating the at least one statistical value, the speed correction method further includes: Determining whether the number of the cycles is greater than a cycle count value, if not, processing the next cycle, if so, stopping processing the next cycle.

15. The speed correction method as claimed in claim 14, the speed correction method further includes: In one of the cycles, determining whether the corresponding distance is greater than a distance threshold value, if so, setting the cycle count value to a first value, otherwise setting the cycle count value to a second value, wherein the first value is greater than the second value.

16. The speed correction method as claimed in claim 13, wherein before the step of calculating the at least one statistical value, the speed correction method further includes: Determining whether the difference between the corresponding first speeds in consecutive n cycles is less than a speed threshold value and the difference between the corresponding second speeds is less than the speed threshold value, if so, stopping processing the next cycle, otherwise processing the next cycle, wherein n is a positive integer greater than 1.

17. The speed correction method as claimed in claim 11, wherein the at least one statistical value includes an average value and a standard deviation of the speeds corresponding to the combinations, and the speed correction method further includes: Setting a clustering range according to the average value and the standard deviation, dividing the speeds within the clustering range into a plurality of bins, and determining the corrected speed according to the bin with the most repetitions among the bins.

18. The speed correction method as claimed in claim 17, the speed correction method further includes: Set the clustering range to be between the average value minus the standard deviation and the average value plus the standard deviation.

19. The speed correction method according to claim 17, the speed correction method further comprising: Set the median value of the slot with the most repetitions as the corrected speed.

20. The speed correction method according to claim 11, the speed correction method further comprising: Execute a clustering algorithm, an association algorithm or a tracking algorithm according to the corrected speed.

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