A three-dimensional positioning method of ultra-wideband radar

Abstract

This invention belongs to the field of UWB wireless positioning technology, specifically providing an ultra-wideband radar three-dimensional positioning method. First, a transceiver antenna array is constructed, with elements arranged in an N×N square array, where N is an odd number ≥ 3. A transceiver antenna is placed at the center of the array, and receiving antennas are placed on the other elements. Based on the transceiver antenna at the center of the array, the arrival time of the target echo signal is collected, starting from the feeding moment, and the transmit / receive time difference is calculated. Then, based on any three receiving antennas located at the four corners of the transceiver antenna array, the arrival time of the target echo signal is collected, and the relative time difference between the three receiving antennas is calculated. Based on the transmit / receive time difference and the relative time difference, the target position coordinates are calculated using a three-dimensional positioning model. In summary, this invention constructs a three-dimensional positioning mathematical model based on the radiation characteristics of an electromagnetic time domain (TEM) antenna array. This model can significantly reduce computational complexity while ensuring positioning accuracy.

Description

Technical Field

[0001] This invention belongs to the field of UWB wireless positioning technology, and specifically provides an ultra-wideband radar three-dimensional positioning method. Background Technology

[0002] With the development of ultra-wideband (UWB) technology, UWB radar has received increasing attention due to its advantages such as wide spectrum, short time-domain pulses, and low power spectral density, and is widely used in wireless communication, positioning, and ground-penetrating radar. UWB technology, with its wide spectrum characteristics (relative bandwidth ≥25% or absolute bandwidth ≥500MHz), nanosecond-level short time-domain pulse waveforms, and low power spectral density characteristics below -41.3dBm / MHz, has built unique technical advantages in the fields of electromagnetic signal transmission and spatial sensing. These technical characteristics make it irreplaceable in strategic fields such as wireless communication, high-precision positioning, and ground-penetrating radar, and it has become a reliable choice for short-range wireless positioning.

[0003] Whether it's traditional GPS navigation and positioning, or the recently emerging short-range wireless positioning technologies such as Wi-Fi, Bluetooth, and ZigBee, researchers both domestically and internationally have proposed various positioning methods to improve positioning accuracy for different application scenarios. In existing UWB positioning systems, there are multiple range-based positioning methods, each corresponding to different algorithms for calculating positioning accuracy. Improving positioning accuracy to meet positioning needs in different environments has always been a key focus of UWB wireless positioning technology.

[0004] However, existing UWB 3D positioning technology still faces significant challenges in complex electromagnetic environments. Problems such as non-line-of-sight (NLOS) propagation errors caused by multipath effects, phase distortion caused by array antenna mutual coupling, and degradation of time difference measurement accuracy under broadband noise interference make the root mean square error (RMSE) of traditional positioning methods generally exceed 0.5m in industrial environments, urban canyons, and other scenarios, which is difficult to meet the needs of practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-wideband radar three-dimensional positioning method. A three-dimensional positioning mathematical model is constructed based on the radiation characteristics of an electromagnetic time domain (TEM) antenna array. This model can significantly reduce computational complexity while ensuring positioning accuracy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A three-dimensional positioning method using ultra-wideband radar, characterized by comprising the following steps:

[0008] Construct a transceiver antenna array, with the array elements arranged in an N×N square array, where N is an odd number ≥3. A transceiver antenna is set at the center of the array, and receiving antennas are set at the other array elements.

[0009] Based on the transceiver antenna at the center of the array, the timing of the feed is taken as the starting point, the arrival time of the target echo signal is collected, and the transmission and reception time difference is calculated.

[0010] Based on any three of the four receiving antennas located at the corners of the transceiver antenna array, the arrival time of the target echo signal is collected respectively, and the relative time difference between the three receiving antennas is calculated.

[0011] The target location coordinates are calculated using a three-dimensional positioning model based on the transmit / receive time difference and relative time difference.

[0012] Furthermore, the calculation process for the relative time difference is as follows: The three receiving antennas are numbered sequentially from first to third receiving antenna in a clockwise or counterclockwise direction. The arrival times of the corresponding target echo signals are as follows: , , Therefore, the relative time difference can be calculated: , .

[0013] Furthermore, the radial distance in the target location coordinates for:

[0014] ,

[0015] in, At the speed of light, Let be the side length of the square array. This is due to the time difference between sending and receiving data.

[0016] Furthermore, the pitch angle in the target position coordinates for:

[0017] ,

[0018] in, At the speed of light, Let be the side length of the square array. and This refers to the relative time difference.

[0019] Furthermore, the horizontal angle in the target position coordinates for:

[0020] ,

[0021] in, and This refers to the relative time difference.

[0022] Based on the above technical solution, the beneficial effects of the present invention are as follows:

[0023] This invention provides an ultra-wideband radar three-dimensional positioning method. First, an ultra-wideband transceiver antenna array is constructed, consisting of an N×N square array. A transceiver antenna is set at the center of the array, and the remaining array elements are set as receiving antennas. Based on the central transceiver antenna, the arrival time of the echo signal is collected from the feeding moment to obtain the transmit-receive time difference. At the same time, any three receiving antennas at the four corners of the array are selected to collect the arrival time of the echo signal and calculate the relative time difference between each pair. On this basis, the radial distance of the target is calculated using the transmit-receive time difference, and the elevation and horizontal angles of the target are directly and analytically solved using a three-dimensional positioning model in spherical coordinates in conjunction with the relative time difference.

[0024] By employing the specific array structure comprised of a central transceiver antenna and four corner receiving antennas, and combining it with a step-by-step analysis strategy based on time difference and relative time difference, the entire positioning process eliminates the need for complex iterative searches or high-dimensional matrix operations. Only algebraic solutions to a small number of time difference measurements are required to quickly calculate the target's three-dimensional coordinates, thus significantly reducing computational complexity while maintaining positioning accuracy. Furthermore, since only three receiving antennas at the four corners of the array are used in the positioning calculation, redundant calculations and synchronization error accumulation caused by full array data fusion are avoided, further improving the real-time performance and stability of the positioning system. Ultimately, this invention offers advantages such as a simple positioning process, low computational resource consumption, and strong engineering feasibility. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the positioning principle of the ultra-wideband radar three-dimensional positioning method in this invention.

[0026] Figure 2 The image shows the simulation results of the ultra-wideband radar three-dimensional positioning method in this invention.

[0027] Figure 3 This is a diagram showing the field experimental positioning results of the ultra-wideband radar three-dimensional positioning method of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] This embodiment provides an ultra-wideband radar three-dimensional positioning method. From the perspective of positioning principles:

[0030] like Figure 1 As shown, the left figure is a schematic diagram of the antenna array, and the right figure is a schematic diagram of the spherical coordinate system calculation of the target and the receiving antenna; for For a point target, the scattered echo signal arrives at three or more non-collinear receiving antennas of the antenna array with a time difference. This time difference can be used to determine the target's location.

[0031] A receiving antenna is set at the center of the array (0,0,0). Let t be the time difference from the feeding time to the antenna receiving the target signal. 00 (Taking the antenna feeding time as the starting point of the timing), then the radial distance of the target from the center of the array is:

[0032] (1)

[0033] in, At the speed of light, The radial distance of the target from the center of the array;

[0034] Record t 00 The radial distance r of the target object can be obtained from equation (1);

[0035] Let t be the time difference between the moment when the i-th receiving antenna receives the signal and the start of the timing. i0 Then the radial distance r measured by the antenna to the target i for:

[0036] (2)

[0037] Where (x,y,z) are the target position coordinates, (x...y...z) i ,y i () represents the position coordinates of the i-th receiving antenna;

[0038] The time difference t between the antennas numbered i and j receiving the target signal ij for:

[0039] (3)

[0040] in, and This represents the distance from the projection of the target point onto the xoy plane to the i-th and j-th receiving antennas. Indicates the target's pitch angle. Indicates the horizontal angle of the target;

[0041] To facilitate the analytical solution of the target position coordinates Take as Figure 1 Any three of the receiving antennas located at the four corners of the array shown; specifically, in this embodiment, the three receiving antennas numbered ①, ②, and ③ are selected as receiving antennas;

[0042] By combining antenna numbers ① and ③, we can obtain:

[0043] (4)

[0044] in, Let be the side length of the square array antenna;

[0045] Similarly, by combining antenna numbers ① and ②, we can obtain...

[0046] (5)

[0047] Therefore, the target location coordinates are:

[0048] (6)

[0049] In the above formula, t 12 t 13 It can be calculated from equation (3):

[0050] (7)

[0051] Transforming equations (1) to (6) into spherical coordinate system parameters, we get:

[0052] (8)

[0053] The beneficial effects of the present invention will be explained in detail below, combining target positioning error analysis, simulation experiments, and field experiments.

[0054] 1. Radial distance error;

[0055] The radial distance of the target is determined using equation (1) or equation (2) (i.e., the mirror distance of the target is determined by the time difference between the signal received by each receiving antenna and the start of the feed timing). To determine the mirror distance test error, the total differential of equation (1) is obtained as follows:

[0056] (9)

[0057] Pick 50 ps The radial distance is 7.5 mm; therefore, the radial distance of the target is determined by the time difference between the transmission and reception of signals by each receiving antenna, which has a test accuracy on the order of cm.

[0058] 2. Angular positioning accuracy;

[0059] for To determine the angular positioning accuracy, we can take the total differential of the second equation in equation (8) to obtain... Angular positioning accuracy:

[0060] (10)

[0061] Considering that the signals received by the receiving antennas are acquired by the same receiver, it can be assumed that the receiver's time jitter is approximately equal for different receiving antennas, i.e., it is assumed that... Then equation (10) can be simplified to:

[0062] (11)

[0063] when When, take an approximation The first equation in equation (3) can be simplified to:

[0064] (12)

[0065] when or At that time, take 5 ps If it is 2m, then The value is 0.75 mrad; the calculation results show that the time difference positioning method gives... The angular error is approximately 2 mrad.

[0066] for Similarly, for angular positioning accuracy, taking the total differential of the third equation in equation (8), we can obtain... Angular positioning accuracy:

[0067] (13)

[0068] The calculation results show that the time difference positioning method provides The angular error is on the order of 3 mrad.

[0069] 3. Simulation experiment;

[0070] This embodiment uses CST electromagnetic simulation software for simulation verification. In the simulation model, the TEM array antenna is arranged in a 1m×1m array, and the target is set as a square metal plate with geometric dimensions of 21 cm×21 cm and a thickness of 2 cm. The material property is defined as an ideal conductor (PEC). The excitation signal is a first-order Gaussian pulse with a peak-to-peak pulse width of 500 ps. After completing the simulation settings, the transient solver is run to obtain the target scattering response. The simulation results are as follows: Figure 2 As shown, the positioning error is within the calculation range, indicating that this simulation is effective and feasible.

[0071] 4. Field experiment;

[0072] This embodiment verifies the simulation results using an outdoor experimental environment. The experiment was conducted in an open microwave anechoic chamber to eliminate multipath interference. The physical dimensions of the TEM array antenna remained consistent with the simulation, arranged in a 1m×1m planar array configuration. The target was a 21cm×21cm, 2cm thick metal plate made of aluminum alloy (approximately the ideal conductor PEC condition in the simulation). The excitation source was a first-order Gaussian pulse signal with a peak-to-peak pulse width of 500ps generated by an arbitrary waveform generator, which was then amplified and fed into the array antenna. The target azimuth angle was controlled by a high-precision turntable, and the target echo data was recorded by a vector network analyzer or a broadband oscilloscope. The same positioning algorithm as in the simulation was applied to calculate the target position, and the target positioning result was obtained as follows: Figure 3 As shown in the figure; the results show that the positioning system achieved effective positioning at all six preset test points, and the root mean square error (RMSE) of the overall positioning was 0.2509m.

[0073] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A method of three-dimensional positioning with ultra-wideband radar, characterized in that, Includes the following steps: Construct a transceiver antenna array, with the array elements arranged in an N×N square array, where N is an odd number ≥3. A transceiver antenna is set at the center of the array, and receiving antennas are set at the other array elements. Based on the transceiver antenna at the center of the array, the timing of the feed is taken as the starting point, the arrival time of the target echo signal is collected, and the transmission and reception time difference is calculated. Based on any three of the four receiving antennas located at the corners of the transceiver antenna array, the arrival time of the target echo signal is collected respectively, and the relative time difference between the three receiving antennas is calculated. The target location coordinates are calculated using a three-dimensional positioning model based on the transmit / receive time difference and relative time difference.

2. The method of claim 1, wherein, The calculation process of the relative time difference is as follows: the three receiving antennas are sequentially numbered as the first receiving antenna to the third receiving antenna in a clockwise or counterclockwise direction, and the corresponding target echo signal arrival times are sequentially , , , and the relative time difference is calculated as , .

3. The ultra-wideband radar three-dimensional positioning method according to claim 1, characterized in that, Radial distance in target position coordinates is: ， wherein is the speed of light, is the side length of the square array, is the transceiver time difference.

4. The ultra-wideband radar three-dimensional positioning method according to claim 2, characterized in that, Pitch angle in target position coordinates is: ， wherein is the speed of light, is the side length of the square array, and is the relative time difference.

5. The ultra-wideband radar three-dimensional positioning method according to claim 2, characterized in that, Horizontal angle in target position coordinates is: ， wherein with is the relative time difference.

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