Radar angle measurement technical method using phased array

Abstract

The invention discloses a radar angle measurement technical method using a phased array. The method comprises the following steps: (1) generating a scanning beam by using a phased array; used scanning beams comprise conventional beams, difference beams and other special beams; the difference beam is obtained by applying additional pi phase offset to one of two sub-arrays containing the same number of array elements; (2) performing integral operation on far-field distribution of the phased array to obtain integral far-field data; (3) scanning the target area, receiving a signal reflected by the target, and measuring the intensity of the reflected signal; and (4) calculating the width and the position of the target object according to the integral far-field data and the reflected signal intensity. According to the method, on the basis that the performance of a transmitting end device is not changed, the accuracy of object angle measurement is improved, meanwhile, the width information of the object is provided, and development of a more accurate and more reliable radar angle measurement technology is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of radar angle measurement technology, and specifically to a high-precision radar angle measurement method based on a phased array. The method achieves fast angle scanning through non-mechanical beam control, and innovatively combines difference beam and integral amplitude analysis technology to simultaneously measure the angle position and width information of the target. It is suitable for scenes with high precision requirements such as laser radar (LiDAR), radar, machine vision, and free space communication. Background Art

[0002] As an emerging technology, phased array has non-mechanical beam steering control capability, which can achieve fast and accurate beam scanning and angle measurement. Compared with traditional mechanical radar systems, it has faster response speed, wider field of view and higher accuracy, so it has broad application prospects in radar, laser radar (LiDAR), free space communication and other fields.

[0003] For an ideal phased array, it is necessary to ensure that the distances of each unit path are completely equal during design, that is, the near-field phase of the transmitting array is aligned, so that a directional collimated beam can be formed in the far field. In addition, in the case of near-field phase alignment, based on the known phase information of each channel, the gradient of the near-field equivalent phase plane can be adjusted to control the direction of the formed beam.

[0004] The existing radar angle measurement technology uses the angle measurement by comparing amplitude (AMCA) to determine the target's angular position by scanning the target and comparing the power of the reflected signal. However, the traditional angle measurement by comparing amplitude has certain limitations in measurement accuracy, especially when the target width is large or the reflected signal is weak, the measurement error is large. In addition, the traditional angle measurement by comparing amplitude usually ignores the width information of the target, resulting in the inability to accurately estimate the geometric size of the target in practical applications. Summary of the invention

[0005] In order to improve the accuracy of radar angle measurement and expand its application range, the present invention proposes a radar angle measurement technology method using a phased array. By introducing a difference beam (Difference Beam) and an angle measurement by comparing integrated amplitude (AMCIA), the width information of the target can be estimated while performing high-precision angle measurement. The method was eventually named Angle Measurement by Comparing Integrated Amplitude of Difference Beam (AMCIAD).

[0006] The technical solution of the present invention is as follows: A radar angle measurement method using a phased array comprises the following steps:

[0007] (1) Generate sum beam (conventional beam): Generate sum beam using phased array, with one main lobe.

[0008] First, use the phased array to generate a sum beam. The sum beam is formed by the same phase difference excitation of adjacent array elements (the phased array has a uniform phase gradient), has a single main lobe and high intensity, and is suitable for preliminary detection and positioning of targets. In the phased array, the generation of the sum beam is a key step in achieving high-precision angle measurement.

[0009] (2) Generating a difference beam: Based on the set phase of each array element of the conventional beam, a difference beam is generated using a phased array. The difference beam is formed by the interference of two beams with opposite phases, and has two adjacent main lobes and a central trough. The central trough of the difference beam can be used to accurately locate the target, while the two main lobes provide angle comparison information. The generation method of the difference beam includes: A. Divide the phased array into two subarrays, each containing half the elements; B. Apply an additional π phase shift to all array elements of one of the subarrays so that the beams of the two subarrays interfere in the far field to form a difference beam.

[0010] (3) Generate other special beams: by controlling the phase and amplitude of each element in the phased array.

[0011] 2. Collect the integrated far field: Integrate the far field distribution of the phased array to obtain the integrated far field amplitude ratio matrix; 3. Scan the target: By adjusting the phase difference between array elements, dynamically adjust the pointing angle of the difference beam to cover the area where the target may exist. And use a power detector to measure the power of the reflected signal. The specific steps include: A. By adjusting the phase difference of the phased array elements, the pointing angle of the beam is changed to obtain the reflected signal power at different angles.

[0012] B. The beam scanning the target includes uniform spacing scanning and non-uniform spacing scanning.

[0013] 4. Calculate the angle and width: Calculate the angle position and width of the target through the integral amplitude comparison method (AMCIAD). The specific steps include: A. Select three key points in the reflected signal power curve for calculation, which are recorded as , and ; B. Using the far-field intensity distribution and reflected power of the difference beam, the angular position and width of the target are determined by minimizing the variance of the integrated amplitude ratio matrix.

[0014] Furthermore, in step 1, the method for generating the sum beam may include, in addition to optimizing the phase error of the phased array using a particle swarm optimization (PSO) algorithm, also improving the quality of the sum beam using algorithms such as a rotation vector method and a neural network optimization algorithm.

[0015] Furthermore, in step 1, in addition to equally dividing the difference beam into two sub-arrays, the method for generating the difference beam may also change the ratio of the number of array elements to change the height ratio of the two main lobes of the generated difference beam.

[0016] Furthermore, in step 1, in addition to generating the special beams by regulating the phase and amplitude of each array element in the phased array, the subarray division technology can also be used to generate multiple independent subarrays, and each subarray can be independently controlled and acquired.

[0017] Furthermore, in step 2, a detector is used to complete the far-field data acquisition of the difference beam, and the integration time of the detector is 1 ms. When measuring the far field, the detector needs to be mounted on a mobile platform and rotated relative to the phased array to collect a wide range of far fields.

[0018] Furthermore, in step 2, the calculation formula of the integral amplitude ratio matrix is: ; in, , and They are , and The corresponding far-field intensity distribution of the difference beam is, , and is the weight coefficient, and are the starting and ending angles of the target.

[0019] Furthermore, in step 3, the reflected power is measured by a detector, the integration time of the detector is 1 ms, and the detector has a fixed position when measuring the reflected signal to ensure acquisition accuracy.

[0020] Furthermore, in step 4, the angular position and width of the target are determined by minimizing the following formula: ; When T takes the minimum value, the corresponding and is the angular range of the object to be measured. The width of the object can be expressed as , the center position of the object can be expressed as .

[0021] Compared with the prior art, the present invention has the following advantages: A. High-precision angle measurement: By introducing the difference beam and integral amplitude comparison method, the present invention can significantly improve the accuracy of angle measurement. According to the implementation results, the proposed radar angle measurement technology method using a phased array has a measurement accuracy that is about 4 times higher than that of the traditional amplitude comparison angle measurement method.

[0022] B. Target Width Estimation: The present invention can not only measure the angular position of the target, but also estimate the width information of the target, which is applicable to a wider range of application scenarios. The error range estimation of the center position based on the width estimation reserves error tolerance for radar applications.

[0023] C. All-solid-state design: Based on the non-mechanical scanning method of phased array, it has faster response speed and higher reliability, and is suitable for high-speed and high-precision radar angle measurement applications.

[0024] D. Strong anti-interference ability: The integral algorithm effectively suppresses the influence of noise and maintains stable performance under low signal-to-noise ratio conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a schematic diagram of a process for measuring the angle and width information of an object in an embodiment of the present invention.

[0026] Figure 2 The figure is a schematic diagram of the instrument in the embodiment of the present invention.

[0027] Figure 3 1 is a far-field diagram of the sum beam and difference beam generated by the phased array in an embodiment of the present invention.

[0028] Figure 4 Schematic diagram of a series of difference beam far-fields for far-field scanning in an embodiment of the present invention.

[0029] Figure 5 This is a graph showing changes in the intensity of the reflected signal received by the power detector in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following examples are provided for a better understanding of the present invention and are not intended to limit the present invention to the best embodiment. Where specific test or analysis steps are not specified in the examples, conventional test or analysis steps described in the literature in the art may be used. All instruments or equipment used are conventional instruments or equipment that can be purchased commercially.

[0031] The present invention provides a radar angle measurement technology method using a phased array, and the specific analysis steps are as follows: 1. This embodiment specifically uses an optical phased array as a transmitting end to generate light beams with different directions, and preferably performs phase optimization through a particle swarm optimization algorithm (PSO algorithm).

[0032] For a phased array with uniform beam splitting, the following beamforming theory is available:

[0033] in is the expected beam angle, and we call the corresponding beam at this time the main lobe. The main lobe is the main energy concentration area of ​​the optical phased array beam, which is usually designed to point in the required direction. is the phase difference between each adjacent array element, is the wave vector of the light source used, is the distance between adjacent array elements.

[0034] By using the phase shifter integrated in each array channel, the , enabling the phased array to achieve beam pointing at any angle.

[0035] The generated phase is optimized using the particle swarm optimization algorithm to make the generated beam have better quality. The benchmarks for evaluating beam quality include sidelobe suppression ratio and half-wave full width. For phased array applications, the above parameters are expected to have smaller values.

[0036] 2. Use array division technology to divide the phased array elements and add an additional π phase offset to a group of elements to generate a difference beam.

[0037] By using array division, the array elements that make up the phased array are divided into two parts, and an additional π phase shift is added to one group of array elements through a phase shifter. Different division ratios will change the ratio of the two main lobe heights of the generated difference beam.

[0038] 3. Collect far-field information of the difference beam.

[0039] The optical power detector is used to detect and store the far-field pattern information of the generated difference beam. The purpose of this step is to generate a far-field ratio matrix of the difference beam.

[0040] ; in, , and They are , and The corresponding far-field intensity distribution of the difference beam is, , and is the weight coefficient, and are the starting and ending angles of the target, respectively.

[0041] 4. Scan the beam and record the reflected signal power.

[0042] The generated difference beams with different directions are used for scanning, and the intensity information of the reflected signal is detected by a power detector, which is then plotted to form a reflection intensity variation curve.

[0043] Select three key points in the reflected power curve, namely the central valley ( ) and two adjacent peaks ( and ).

[0044] 5. Solve object information.

[0045] Use the following formula to solve the object information: ; When T takes the minimum value, the corresponding and is the angular range of the object to be measured. The width of the object can be expressed as , the center position of the object can be expressed as . Example

[0046] In order to better understand the technical content of the present invention, specific embodiments are cited and described as follows in conjunction with the accompanying drawings. Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily defined to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in the present invention are not limited to any implementation. In addition, some aspects disclosed in the present invention can be used alone, or in any appropriate combination with other aspects disclosed in the present invention.

[0047] In this embodiment, the design of the device has the same process framework and instrument design, such as Figure 1 and 2 The optical phased array used is a 32-channel silicon-based optical phased array chip with an array element spacing of 0.78 , the working wavelength is 1550nm, the array is designed as a special waveguide superlattice structure, which can achieve an angle of more than 120° (-60°~60°), and the beam width is 3.36°; the working wavelength of the selected laser is 1550nm, the output power is 10dBm; the selected surface optical power detector has an input aperture of Φ5mm and an integration time of 1ms; the electric rotating stage used to carry the detector to measure the far field has a rotation range of 0°~360° and a positioning accuracy of 0.003°; the object used for measurement has a width of 1cm; and a computer for data acquisition and processing. These devices together constitute the experimental infrastructure, ensuring the efficient generation of differential beams, accurate scanning of targets, and measurement of reflected light power.

[0048] Step 1: Calibration and difference beam generation of optical phased array First, the optical phased array is calibrated and a difference beam is generated. The phase error is optimized by the particle swarm optimization (PSO) algorithm to ensure the beam quality. The optical phased array is divided into two sub-arrays, each containing 16 channels, and an additional π phase shift is applied to one of the sub-arrays to generate a difference beam, as shown in Figure 3-4 The difference beam appears as two adjacent main lobes and a central valley in the far field, providing a high-precision beam for subsequent target scanning.

[0049] Step 2: Target scanning and reflected light power measurement Next, place the target object on the electric rotating stage, 20 cm away from the optical phased array. Adjust the electric rotating stage so that the initial angle of the target object is 0.5°, use the generated difference beam to scan the target object, and measure the power of the reflected light. Record the Central Valley and two adjacent peaks and Repeat the above steps, adjust the angle of the target object to 2.5°, and measure the reflected light power again. Figure 5 shown.

[0050] Step 3: Data collection and processing Then, the reflected light power data collected by the photodetector is transmitted to the computer. Select three key points in the reflected light power curve , and , the integral amplitude ratio matrix is ​​calculated using the far-field intensity distribution of the difference beam, and the angular position and width of the target are determined by minimizing the variance. The specific calculation includes the generation of the integral amplitude ratio matrix and the minimization of variance analysis.

[0051] Step 4: Result output and verification Finally, the angular position and width of the target object are output according to the calculation results, and the measurement accuracy is verified by comparing the actual angle value of the electric rotary table. The experiment is repeated 100 times, and the measurement error is statistically calculated to evaluate the stability and reliability of the AMCIAD method. The experimental results show that the measurement accuracy of the AMCIAD method is 0.13°, and the width estimation error is less than 10%, which is significantly better than the traditional method.

[0052] The experimental results show that the AMCIAD method achieves high-precision angle measurement and target width estimation at a wavelength of 1550nm. Its angle measurement accuracy reaches 0.13°, which is about 4 times higher than that of the traditional AMCA method, and the target width estimation error is less than 10%. At the same time, under different signal-to-noise ratio conditions, the measurement error of the AMCIAD method decreases with the increase of the signal-to-noise ratio. When the signal-to-noise ratio is 8dB, the measurement error is 0.13°. The experiment verifies the stability and reliability of the method, which is suitable for fields such as laser radar (LiDAR) and free space optical communication, and provides an effective solution for high-precision angle measurement and target size estimation.

[0053] In summary, the present invention provides a radar angle measurement technology method using a phased array. The method includes the following steps: (1) using a phased array as a transmitter and using a phase correction algorithm to generate beams of various directions; (2) using the array element division technology of the phased array to divide the array elements into two parts, and by using a phase shifter integrated in each array channel, simultaneously changing the phase of one group of arrays so that the beam shape is changed from a sum beam of a single main lobe to a difference beam with two adjacent main lobes; (3) recording the far field information of the difference beam and using an integral algorithm to calculate the integrated far field; (4) using the difference beam to scan, and recording the intensity of the received reflected signal through a detector; (5) combining the integrated far field and reflected signal information to calculate the angle position and width ratio of the object. The method of the present invention can improve the accuracy of the angle measurement of the object without changing the performance of the transmitter device, and at the same time provide the width information of the object, which is conducive to the development of more accurate and reliable radar angle measurement technology.

[0054] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the principles, the implementation methods of the present invention may be deformed or modified in any way.

Claims

1. A radar angle measurement method using a phased array, characterized in that: The following steps are involved: (1) Using a phased array to generate a scanning beam; (2) Integrate the far-field distribution of the phased array to obtain the integrated far-field data; (3) Scan the target area, receive the signal reflected by the target, and measure the strength of the reflected signal; (4) Calculating the width and position of the target object based on the integrated far-field data and the reflected signal strength.

2. The radar angle measurement method using a phased array according to claim 1, characterized in that: The scanning beam types used include the following: (1) A conventional beam generated when adjacent elements in a phased array have equal phase differences, which is used to calculate the position and width information of the target object in combination with an integral algorithm; (2) a difference beam, which is a beam generated by causing some elements in the phased array to have an additional phase difference with other elements through a specific structure or control setting based on the set phase of each element of the conventional beam, and is used to improve the measurement accuracy of the integration algorithm; (3) Other special beams are generated by controlling the phase and amplitude of each element in the phased array.

3. The radar angle measurement method using a phased array according to claim 2, characterized in that: The step of generating a conventional beam includes optimizing the phase error of the phased array using a phase optimization algorithm to improve the quality of the beam. The phase optimization algorithm includes but is not limited to a particle swarm optimization algorithm.

4. The radar angle measurement method using a phased array according to claim 2, characterized in that: The step of generating the difference beam comprises: (1) Divide the phased array into two sub-arrays, each containing an equal number of array elements; (2) An additional π phase shift is applied to one of the subarrays so that the beams of the two subarrays interfere in the far field to form a difference beam.

5. The radar angle measurement method using phased array according to claim 4, characterized in that: The method for generating a difference beam further includes adjusting the ratio of the number of array elements of the two subarrays to change the height ratio of the two main lobes of the difference beam.

6. The radar angle measurement method using phased array according to claim 2, characterized in that: The step of generating other special beams also includes generating multiple independent sub-arrays using sub-array division technology and independently controlling each sub-array.

7. The radar angle measurement method using phased array according to claim 1, characterized in that: The step of scanning the target area comprises: (1) By adjusting the phase difference of the phased array elements, the pointing angle of the beam is changed to obtain the reflected signal power at different angles; (2) The beam scanning the target includes uniform spacing scanning and non-uniform spacing scanning.

8. The radar angle measurement method using a phased array according to claim 1, characterized in that: The step of calculating the width and position of the target object comprises: (1) Select three key points in the reflected signal power curve for calculation, which are recorded as , and ; (2) Using the far-field intensity distribution of the difference beam, calculate the target's integrated amplitude ratio matrix. The formula is as follows: ； in, , and They are , and The corresponding far-field intensity distribution of the difference beam is, , and is the weight coefficient, and are the starting and ending angles of the target, respectively; (3) The angular position and width of the target are determined by minimizing the variance of the integral matrix and the reflected signal. The formula is as follows: ； When T takes the minimum value, the corresponding and is the angular range of the object to be measured; the width of the object is expressed as , the center position of the object is expressed as .

9. The radar angle measurement method using phased array according to claim 8, characterized in that: The three key points in the reflected signal power curve correspond to the reflected signals of a trough and two peaks of the difference beam.

10. The radar angle measurement method using phased array according to claim 1, characterized in that: The method is applicable to phased arrays of multiple bands, including but not limited to optical phased arrays, radio frequency phased arrays, and microwave phased arrays.

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