CN-122001469-A - Alignment method of wireless optical communication terminal, computer equipment and wireless optical communication system

CN122001469ACN 122001469 ACN122001469 ACN 122001469ACN-122001469-A

Abstract

The present application relates to the field of optical communications technologies, and in particular, to a wireless optical communications terminal alignment method, a computer device, and a wireless optical communications system. The method is applied to a receiving terminal and comprises the steps of obtaining an image of the sending terminal, extracting a light spot power sequence based on the image of the sending terminal, matching the light spot power sequence with a chaotic sequence, obtaining a channel quality index representing the quality of an optical communication link, constructing an observation noise covariance matrix based on the channel quality index and adjusting the process noise covariance matrix, estimating an alignment error between the receiving terminal and the sending terminal by using Kalman filtering based on the process noise covariance matrix and the observation noise covariance matrix, and generating a control signal according to an estimation result so as to drive an executing mechanism to adjust, thereby realizing optical axis alignment between the communication terminals. The method provided by the application can realize stable and accurate alignment of the optical axis of the wireless optical communication terminal under the complex environments of strong disturbance, low signal-to-noise ratio, high-speed maneuver and the like.

Inventors

Yu Meitong
WANG JIAHENG
ZHU SHICHENG
CHEN JINTING
FENG YI
LING QIANYUN
GAO XIQI

Assignees

紫金山实验室

Dates

Publication Date: 20260508
Application Date: 20260309

Claims (13)

1. A method of aligning a wireless optical communication terminal, applied to a receiving terminal, the method comprising: Acquiring a sending terminal image, wherein the sending terminal image comprises at least one image of a beacon light source arranged on a sending terminal, the beacon light source works according to a chaotic sequence, and the chaotic sequence is generated based on a preset chaotic model; Extracting a light spot power sequence based on the sending terminal image, wherein the light spot power sequence characterizes the working condition of the beacon light source observed by the receiving terminal; matching the facula power sequence with the chaotic sequence, obtaining a channel quality index representing the quality of an optical communication link, constructing an observation noise covariance matrix based on the channel quality index, and adjusting a process noise covariance matrix; Based on the process noise covariance matrix and the observation noise covariance matrix, estimating an alignment error between the receiving terminal and the transmitting terminal by using Kalman filtering, and generating a control signal according to an estimation result so as to drive an executing mechanism to adjust, thereby realizing the alignment of optical axes between communication terminals.
2. The method of claim 1, wherein constructing an observed noise covariance matrix and adjusting a process noise covariance matrix based on the channel quality indicator comprises: Calculating a first product of a preset scale coefficient and the channel quality index; Inputting a preset upper variance limit, a lower variance limit and the sum of the first product and a preset basic measurement variance into a cut-off function, and obtaining a measurement noise variance, wherein the cut-off function is used for adjusting a value larger than the upper variance limit in the first product to be the upper variance limit and adjusting a value smaller than the lower variance limit in the first product to be the lower variance limit; Calculating the product of the measured noise variance and a preset identity matrix to be used as the observed noise covariance matrix; the process noise covariance matrix is calculated using an adaptive Kalman filter based on the observed noise covariance matrix.
3. The method of claim 1, wherein said matching the spot power sequence with the chaotic sequence to obtain a channel quality indicator characterizing the quality of an optical communication link comprises: Calculating a single light source quality index of each beacon light source based on the chaotic sequence and a light spot power sequence corresponding to each beacon light source, wherein the single light source quality index is at least associated with a normalized correlation peak value, and the normalized correlation peak value is calculated based on the following way that based on a preset sliding window, sliding normalized cross correlation is carried out on the light spot power sequence and the chaotic sequence, and the normalized correlation peak value is obtained; based on the normalized correlation peak value of each beacon light source, acquiring the relative weight of each beacon light source; And based on the relative weight, carrying out weighted calculation on the single light source quality index of each beacon light source to acquire the channel quality index.
4. The method of claim 3, wherein the single light source quality indicator is obtained by weighting calculation based on a preset indicator and a corresponding preset weight, the preset indicator at least comprises a difference between a first preset constant and the normalized correlation peak value, and the preset indicator further comprises at least one indicator of system noise, error rate and inverse of signal-to-noise ratio; The error rate is calculated based on the following modes that based on the normalized correlation peak value, transmission delay is determined, based on the transmission delay, the facula power sequence is matched with the chaotic sequence, the number of transmission error elements in the facula power sequence is counted, and the ratio of the number of the transmission error elements to the total number of the counted elements is calculated to be used as the error rate; the signal-to-noise ratio is calculated based on the following modes that the relative power of the beacon light source and the relative power of the background noise are obtained, and the ratio of the relative power of the beacon light source to the relative power of the background noise is calculated as the signal-to-noise ratio; The system background noise is the measurement noise covariance under ideal conditions.
5. The method of claim 4, wherein determining a transmission delay based on the normalized correlation peak value comprises: Determining the current transmission delay based on the normalized correlation peak value; And carrying out weighted calculation on the current transmission delay and the historical transmission delay based on a preset delay weight to determine the transmission delay, wherein the historical transmission delay is the transmission delay acquired in the wireless optical communication terminal alignment operation executed before the current wireless optical communication terminal alignment.
6. The method of claim 1, wherein three beacon light sources are disposed on the transmitting terminal, and the three beacon light sources are arranged in an equilateral triangle, and a geometric center of the equilateral triangle is located on an optical axis of the optical communication device on the transmitting terminal.
7. The method of claim 6, wherein the estimating an alignment error between the receiving terminal and the transmitting terminal using kalman filtering comprises: Calculating the barycentric coordinates of a triangle formed by the three beacon light sources according to the pixel coordinates of the three beacon light sources in the sending terminal image; determining current posture information of the sending terminal based on the barycentric coordinates, and establishing an observation vector based on the current posture information, wherein the current posture information comprises at least one of a yaw angle, a pitch angle and a roll angle; determining a posture information change rate based on the current posture information and the history posture information acquired in the previous wireless optical communication terminal alignment operation, and establishing a state model based on the current posture information and the posture information change rate; Based on the state model, the observation vector, the process noise covariance matrix, and the observation noise covariance matrix, performing a prediction and update step of a kalman filter to estimate an alignment error between the receiving terminal and the transmitting terminal.
8. The method of claim 7, wherein the yaw angle is a ratio of an abscissa offset to a focal length of the image capturing device on a horizontal axis, the abscissa offset being a difference between an abscissa of the barycentric coordinate and an abscissa of an optical axis position of the optical communication device on the receiving terminal; The pitch angle is the ratio of the ordinate offset to the focal length of the image acquisition equipment on the longitudinal axis, and the ordinate offset is the difference between the ordinate of the barycentric coordinate and the ordinate of the optical axis position of the optical communication device on the receiving terminal; The rolling angle is the difference between the current direction angle and a pre-calibrated initial angle, and the current direction angle is obtained by calculating the abscissa of any two beacon light sources in the three beacon light sources through a preset trigonometric function.
9. The method of claim 7, wherein the building a state model based on the current pose information and the rate of change of the pose information comprises: constructing a state transition matrix and an input matrix based on the interval duration between the current wireless optical communication terminal alignment operation and the previous wireless optical communication terminal alignment operation and a preset state transition matrix format and input matrix format; And establishing the state model based on the current gesture information, the gesture information change rate, the observation vector, the state transition matrix, the input matrix and the angular speed of the sending terminal.
10. The method of claim 1, wherein prior to the acquiring the image of the transmitting terminal, the method further comprises: communication with the receiving terminal, and determining chaotic seeds; generating a continuous-time chaotic function by taking a transmission function of a Mach-Zehnder interferometer comprising high-pass filtering and low-pass filtering as the chaotic model based on the chaotic seeds; And performing discretization sampling and data processing on the continuous-time chaotic function to generate the chaotic sequence.
11. The method according to claim 1, wherein the extracting the spot power sequence based on the transmitting terminal image comprises: dark field correction and flat field correction are carried out on the sending terminal image; extracting a region of interest corresponding to each beacon light source of the sending terminal image, and calculating the brightness value of the region of interest; removing average brightness of a background area at the outer edge of the region of interest from a brightness value of the region of interest to obtain a net brightness signal of the region of interest; based on hardware parameters of the image acquisition equipment, carrying out exposure time and gain normalization on the net brightness signal, and obtaining basic relative power of each beacon light source; And normalizing based on the basic relative power of all the beacon light sources, and obtaining all normalized basic relative powers in a preset sliding window to form the light spot power sequence.
12. A computer device, comprising: a memory and a processor communicatively coupled to each other, the memory having stored therein computer instructions that, when executed, perform the wireless optical communication terminal alignment method of any of claims 1-11.
13. A wireless optical communication system, comprising at least one transmitting terminal and at least one receiving terminal, wherein the computer device of claim 12 is mounted on the receiving terminal; the sending terminal is a movable terminal or a fixed terminal, and the receiving terminal is a movable terminal or a fixed terminal.

Description

Alignment method of wireless optical communication terminal, computer equipment and wireless optical communication system Technical Field The present application relates to the field of optical communications technologies, and in particular, to a wireless optical communications terminal alignment method, a computer device, and a wireless optical communications system. Background The wireless optical communication has the advantages of large bandwidth, strong electromagnetic interference resistance and the like, and is widely applied to scenes such as unmanned aerial vehicle communication, satellite relay, emergency communication and the like. The system relies on narrow light beams to realize high-speed transmission, and has extremely high requirements on the optical axis alignment precision of optical communication devices of two communication parties. The conventional optical axis alignment method mainly relies on hardware improvement, for example, satellite positioning data, an inertial measurement unit, image recognition and other technologies are used for calculating the gesture of the optical communication device so as to calculate the optical axis direction. However, the technical means has the defects that on one hand, related data are easily influenced by external disturbance factors such as weather change, atmospheric turbulence and shielding to cause the system performance stability to be insufficient, and on the other hand, the data have low association degree with the quality of a wireless optical communication link, so that the link state change is difficult to effectively reflect, and the further improvement of the alignment precision and the system robustness is limited. On the other hand, the conventional method also attempts to introduce kalman filtering into the alignment error estimation of the optical communication terminal at the software algorithm level. However, the traditional kalman filtering is generally based on the assumption of linear gaussian noise, the movement process of the wireless optical communication terminal has obvious nonlinear characteristics, and the communication noise changes violently along with time, so that the traditional kalman filtering algorithm is difficult to adapt to the application environment with high dynamic and strong time variation, and further the positioning precision and the robustness are difficult to effectively improve. In view of the foregoing, there is a need for a new alignment method for wireless optical communication terminals to achieve more stable and accurate alignment of wireless optical communication terminals. Disclosure of Invention The application provides a wireless optical communication terminal alignment method, computer equipment and a wireless optical communication system, which can realize stable and accurate optical axis alignment of a wireless optical communication terminal under complex application environments such as strong disturbance, low signal-to-noise ratio, high-speed maneuver and the like. In order to achieve the above purpose, the main technical scheme adopted by the application comprises the following steps: In a first aspect, an embodiment of the present application provides a method for aligning a wireless optical communication terminal, which is applied to a receiving terminal, where the method includes: Acquiring a sending terminal image, wherein the sending terminal image comprises at least one image of a beacon light source arranged on a sending terminal, the beacon light source works according to a chaotic sequence, and the chaotic sequence is generated based on a preset chaotic model; Extracting a light spot power sequence based on the sending terminal image, wherein the light spot power sequence characterizes the working condition of the beacon light source observed by the receiving terminal; matching the facula power sequence with the chaotic sequence, obtaining a channel quality index representing the quality of an optical communication link, constructing an observation noise covariance matrix based on the channel quality index, and adjusting a process noise covariance matrix; Based on the process noise covariance matrix and the observation noise covariance matrix, estimating an alignment error between the receiving terminal and the transmitting terminal by using Kalman filtering, and generating a control signal according to an estimation result so as to drive an executing mechanism to adjust, thereby realizing the alignment of optical axes between communication terminals. According to the wireless optical communication terminal alignment method provided by the embodiment of the application, the chaotic sequence is introduced to control the beacon light source to work, and the quality index of the optical communication link is generated through the observation of the working condition of the beacon light source, so that the quality of the communication link becomes the data input capable of being q