A target track-based phased array radar fast switching tracking method and system

Abstract

The application discloses a target track-based phased array radar fast switching tracking method and system, and the method comprises the following steps: establishing a target track in a radar mechanical scanning search mode; after a tracking instruction is issued by a display control terminal, calculating the deviation between the target azimuth and the antenna normal line according to the target track prediction information; and controlling a servo turntable system to drive the array surface to rotate to the target azimuth. After the array surface is rotated to the target azimuth, the radar enters a sector scanning tracking mode, and high data rate tracking beams are inserted in the search beams through resource scheduling. When the target is not detected for more than a certain frame, the radar interrupts the background search and concentrates the beams to the target area for concentrated search, and if the search fails, the radar returns to the mechanical scanning search mode. The application solves the problems of slow tracking mode switching and inflexible beam scheduling of the conventional mechanical scanning radar, and realizes fast and stable tracking of the key target and search and re-supply after the target is lost.

Description

Technical Field

[0001] This invention relates to the field of radar signal processing and control technology, specifically to a rapid switching tracking method and system that combines the wide-area coverage capability of mechanical scanning with the flexibility of phased array electronic scanning. Background Technology

[0002] In modern radar systems, mechanically scanned radars offer the advantage of 360° full airspace coverage, but their low data update rate makes it difficult to continuously and accurately track highly maneuverable targets. While all-solid-state active phased array radars offer flexible beams, their coverage is limited by the array aperture, with a single array typically covering only 90°-120° of the airspace.

[0003] Current "mechanical-phase scanning combined" radars typically employ a simple "rotate-and-scan" mode, meaning electronic scanning is performed during mechanical rotation. However, when operators require continuous, high-precision "staring" or high-data-rate tracking of a high-threat target, existing switching procedures often suffer from the following problems:

[0004] 1. There is a time difference between the detection of a target and the servo turntable stopping and aligning with the target, which can easily cause high-speed targets to fly out of the beam range.

[0005] 2. In tracking mode, radar often ignores the search of the background airspace, resulting in a decrease in situational awareness.

[0006] 3. Once the radar loses its target while tracking the beam, it lacks a flexible hierarchical recovery mechanism and often reverts directly to a full-domain search, resulting in low efficiency. Summary of the Invention

[0007] This invention aims to solve the above-mentioned problems by providing a method that can utilize target trajectory information to assist servo control, achieve seamless and rapid switching from search to tracking, and possess flexible beam scheduling and loss reacquisition mechanisms. The method specifically includes the following implementation steps:

[0008] Step S1: Based on the search command issued by the input radar control terminal, the radar servo turntable drives the phased array antenna to perform a uniform full-space scan. During the scan, the signal processing system performs signal processing on the echo signal according to the mechanical scan search sequence, including digital down-conversion, pulse compression, static clutter suppression, moving target detection, and constant false alarm rate monitoring. The signal processing results are then sent to the data processing system via an interface. The data processing system further filters and processes the target information and outputs the target information to S2. If no target is found, step S1 is maintained.

[0009] Step S2: Based on the target information in S1, the track display system initiates track tracking for the target point. For established tracks, the Kalman filter algorithm is used to update and smooth the target's position, velocity, and acceleration state vectors, forming a stable target track data pool. When a tracking command for a specific target is received, the data processing system extracts the target's current track state vector, predicts the target's azimuth at the next moment based on the current time and the expected response delay time of the servo turntable system, and outputs the predicted target azimuth to S3.

[0010] Step S3: Based on the target predicted azimuth angle input in S2, the signal processing system calculates the angular deviation between the target predicted azimuth angle and the current antenna array normal in real time. Based on this deviation, it plans the optimal rotation path (clockwise or counterclockwise) for the servo turntable and generates position and speed commands to drive the servo turntable system to rotate rapidly. During the servo turntable rotation, the angular deviation between the target and the antenna normal is monitored in real time. When this angular deviation is less than the sector scan range of the phased array antenna, the mode switching command is output to S4 without waiting for the servo turntable to completely stop. If the angular deviation is greater than or equal to the sector scan range of the phased array antenna, step S3 is maintained.

[0011] Step S4: Based on the mode switching command output in S3, without waiting for the servo turntable to completely stop, the signal processing system immediately switches the mechanical scan search sequence to the sector scan tracking sequence. Utilizing the rapid deflection capability of the phased array electronic beam, it compensates for mechanical dynamic errors during the servo turntable's rotation, establishing a tracking beam pointing towards the target in advance, achieving a seamless switch from mechanical scan search mode to tracking mode. In sector scan tracking mode, beam resources are searched, and tracking beams are interleaved and scheduled. Once the servo turntable has rotated to its position and locked onto the target's azimuth, it enters a stable sector scan tracking mode. In this mode, a resource scheduling strategy combining time-slice rotation and priority preemption is adopted: 1. Tracking beam allocation: Based on the target's threat level and motion characteristics, the required target echo update rate is calculated, and a fixed time slice is allocated in the radar time resource frame for transmitting the tracking beam. 2. Search beam interleaving: During the time interval between two adjacent tracking beam transmissions, a sector scan search beam is inserted. The search beam scans according to a preset grating, covering a specific sector of the background airspace centered on the target to detect new targets or monitor the surrounding situation. The signal processing system processes the echo in real time and outputs the signal processing results of the tracking beam to S5.

[0012] Step S5: Based on the tracking beam signal processing results output in sector scan tracking mode in S4, the data processing system performs target filtering on the echoes of the tracking beam in real time. If target information can be filtered out in each frame, step S4 is maintained; otherwise, the following hierarchical decision and processing logic is executed based on the number of frames in which no target is detected: Level 1 decision: If no target echo is detected in consecutive frames M, the current sector scan tracking mode remains unchanged, track filtering updates are stopped, the data processing expands the gate search range, and predictive track information is output to S5.1 based on the existing track. Step S5.1 updates the target track on the track display interface and associates it based on the input track prediction information. Level 2 decision: If no target is detected in consecutive frames N, it is determined that the target is temporarily lost, and the radar control terminal outputs a mode switching command to S5.2. Step S5.2, based on the input mode switching, the signal processing system switches the beam scheduling mode, interrupts the background search beam, and switches to sector scan search mode. A high data rate, high density local search and reacquisition is performed within a preset azimuth and elevation range, centered on the predicted position of the target's last disappearance point. Level 3 processing: If the target cannot be recaptured after more than N frames, it is determined that the target is completely lost, and the target loss result is output to S6.

[0013] Step S6: Based on the target loss result output in S5, the track display interface clears the target track and controls the servo turntable to resume uniform rotation. The radar operating mode is switched back to the mechanical scan search mode described in step S1, and a full-space search is performed again. The radar stops operating upon receiving the end-scan command; otherwise, it continues operating in mechanical scan search mode.

[0014] Compared to existing technologies, this invention has the following significant advantages: 1. Utilizing the wide electronic scanning range of the phased array antenna, tracking can be initiated in advance through electronic beam deflection before the servo turntable has reached its rotation position, eliminating the "blind spot time" caused by mechanical inertia and significantly reducing the escape probability of high-speed maneuvering targets during mode switching. 2. In tracking mode, a beam scheduling strategy of "tracking + search" is adopted, which ensures high data rate and precise tracking of key targets without sacrificing situational awareness of the background airspace, maximizing the radar aperture time efficiency. 3. A three-level perception mode switching mechanism is designed, from "enlarged gate" to "local reacquisition" to "full-domain search," effectively solving the tracking instability problem caused by short-term target obstruction, violent maneuvering, or clutter interference, and avoiding frequent and unnecessary radar mode restarts. Attached Figure Description

[0015] Figure 1 The main flowchart of the method provided in the embodiment of the present invention.

[0016] Figure 2 This is a block diagram of a radar system architecture provided for an embodiment of the present invention.

[0017] Figure 3 This is a timing diagram of beam resource scheduling (search and tracking interleaving) in sector scan tracking mode. Detailed Implementation

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] like Figure 1 As shown, the system mainly includes: 1. Phased array antenna: performing radio frequency transmission and reception. 2. Signal processing system: responsible for controlling the radar transmission and reception timing and receiving echoes for signal processing. 3. Servo turntable system: providing feedback on the current mechanical azimuth angle θ. mech 4. Data processing system, responsible for track filtering, coordinate transformation, etc. 5. Track display interface, displaying the processed track on the screen. 6. Radar terminal control, issuing various operating mode commands to the signal processing system.

[0020] This method mainly consists of six stages: mechanical scanning, track establishment, angle deviation calculation, command issuance, sector scanning and tracking, and target loss and mode rollback. The processing flow of the six stages is as follows:

[0021] S1: To search for targets across the entire airspace, first input the mechanical scan search mode command. The radar array emits a radio frequency beam along the normal direction, and the servo turntable drives the antenna to rotate at a constant angular velocity ω (e.g., 6 rpm). Assuming a target is detected at time k, the measured value is (r k θ k , φ k (Range, azimuth, pitch), the data processing system uses Kalman filtering to estimate the target state. Through Kalman filtering, a smooth trajectory definition state vector X can be obtained. k =[x, v x ,y,v y ,z,v z ] T The state update equation is:

[0022] X k|k =X k|k-1 +K k (Z k -HX k|k-1 )

[0023] Among them, Z k K is the observation vector. k To obtain the Kalman gain, the target information is output to S2.

[0024] S2: Based on the target information output by S1, the track display interface establishes the target point track and updates the target track. The data processing system updates the position X at the next moment according to the state update equation. k+1 With its predictive capabilities, after the control terminal issues a tracking command for the target position, the data processing system outputs the predicted target azimuth angle to S3 based on the track state vector.

[0025] S3: Based on the predicted target azimuth angle input in S2, when the display and control terminal issues the command "track target ID=n", the angle deviation calculation logic is entered:

[0026] The first step is to determine the current time t. now and the response delay Δt of the servo system servo The data processing system predicts the azimuth angle θ of the target at the moment of antenna alignment. target (t now +Δt servo ).

[0027] The second step involves the signal processing system calculating the deviation between the predicted target orientation and the current mechanical axis orientation: Δθ = θ pred -θ mech .

[0028] Third step, if |Δθ|>θ scan-max (Maximum electronic scanning angle of the phased array): The servo turntable system rotates at full speed to the target position. If |Δθ|≤θ scan-max At this point, there's no need to wait for the servo to completely stop; electronic beam tracking is immediately activated. The electronic scanning capability of the phased array is used to compensate for mechanical deviations. Beam pointing angle calculation formula:

[0029] θ beam =θ target -θ mech

[0030] Phase shifters are used to load the phase, ensuring the beam always points towards the target in space, thus offsetting dynamic errors caused by mechanical rotation. When the angular deviation is less than the sector sweep range of the phased array antenna, the mode switching command is output to S4 without waiting for the servo turntable to completely stop. If the angular deviation is greater than or equal to the sector sweep range of the phased array antenna, step S3 is maintained.

[0031] S4: Based on the mode switching command output by S3, without waiting for the servo turntable to completely stop, the signal processing system immediately switches the mechanical scan search timing to the sector scan tracking timing, and at the same time updates the beam resource scheduling mode, so that the radar enters a stable sector scan state.

[0032] Beam resource scheduling model: Let the radar scheduling time frame be T. frame In the sector scan search mode, the radar needs to cover a sector range Ω. SThe required number of beams is N S When tracking the selected target, the required data rate is f. track Scheduling algorithm flow: 1. First, schedule T... frame 1. Divide into several time slices. 2. Based on the tracking beam dwell time τ track Arrange the tracking beams according to their pointing direction (given by the filter prediction value). 3. Fill the gaps between the tracking beams with search beams, with the dwell time of the search beams being τ. search The resource utilization rate η can be formally described as follows:

[0033]

[0034] If η > 1, the search area size or search data rate is reduced to prioritize tracking. The search beam scans according to a preset grating to cover a specific sector of the background airspace centered on the target, in order to discover new targets or monitor the surrounding situation. The signal processing system processes the echoes in real time and outputs the signal processing results of the tracking beam to S5.

[0035] S5: Based on the tracking beam signal processing results output in sector scan tracking mode in S4, the data processing system performs target filtering on the echo of the tracking beam in real time. If target information can be filtered out in each frame, step S4 is maintained. If tracking is interrupted due to target maneuvering or obstruction, the radar data processing system and radar control terminal are designed with multi-state processing logic:

[0036] 1. Stable State Decision: The decision condition is that the data processing system successfully detects the target continuously. The radar maintains the sector scan tracking mode and continuously updates the track. 2. First-Level Decision: The decision condition is that the data processing system does not detect the target for 1 to M consecutive frames. The current sector scan tracking mode remains unchanged, track filtering updates are stopped, the data processing expands the gate search range, only performs prediction extrapolation, and outputs predicted point track information to S5.1 based on the existing track. Step S5.1 updates the target track on the track display interface and associates it with the input track prediction information. 3. Second-Level Decision: The decision condition is that the data processing system does not detect the target for M to N consecutive frames, and the radar control terminal outputs a mode switching command to S5.2. Step S5.2, based on the input mode switch, interrupts the background search and uses the target's last vanishing point (r) as the starting point. last θ last , φ last Centered on ), within the range ±Δθ reacq High-density, small-step raster scanning is performed internally. If a target is detected at this time, the system immediately resumes sector scanning tracking. 4. Third-level processing: The decision condition is that the data processing system has not detected a target for more than N consecutive frames. At this time, the data processing system reports "target lost" to the track display interface and outputs the target loss result to S6.

[0037] S6: Based on the target loss result output in S5, the track display interface clears the target track and controls the servo turntable to resume uniform rotation, switching the radar operating mode back to the mechanical scan search mode described in step S1, and re-performing a full-space search. The radar terminates operation upon receiving a stop-scan command; otherwise, it continues operating in mechanical scan search mode.

Claims

1. A method for rapid switching and tracking of a phased array radar based on a target trajectory, characterized in that, Includes the following steps: Step S1: Input the search command from the radar control terminal. The radar operates in mechanical scanning search mode. The antenna array rotates 360° at a constant speed with the servo turntable. The signal processing system processes the echo and transmits the signal processing result to the data processing system for target filtering. If the data processing system filters out target information, it outputs the target information to S2. Otherwise, repeat step S1. Step S2: Based on the target information input in S1, establish the target point and update the target track on the track display interface. Then, the control terminal sends a tracking command to the radar based on the target position information. The data processing system extracts the current track state vector of the target, calculates it, and outputs the predicted azimuth of the target to S3. Step S3: Based on the target predicted azimuth angle input in S2, the signal processing system calculates the angle deviation between the predicted azimuth angle and the current antenna array normal in real time. At the same time, the signal processing system drives the servo turntable to rotate the antenna array normal to the target predicted azimuth. If the angle deviation is less than the sector sweep range, output the mode switching command to S4; otherwise, repeat step S3. Step S4: According to the mode switching command input in S3, the signal processing system processes the echo in the sector scan tracking mode. The beam scheduling adopts the time slice rotation method. The tracking beam for the target is inserted into the fixed sector scan search beam sequence. The servo turntable rotates to the target position and is fixed. The signal processing result of the tracking beam is output to S5. Step S5: Based on the tracking beam signal processing result output in S4, the data processing system processes the tracking beam signal processing result in real time. If it is determined that the target has not been lost, step S4 is maintained. If the target is lost, the data processing system enters the first-level decision: If no target is detected in frames 1 to M, the data processing system outputs predicted point information based on the existing track to S5.

1. Otherwise, it enters the second-level decision: If no target is detected in frames M to N, the radar control terminal outputs a mode switching command to S5.

2. Otherwise, it outputs the target loss result to S6. Step S5.1: The predicted point information output from S5 is sent to the track display interface, which then associates the existing track with the predicted point. Step S5.2: According to the mode command output by S5, switch the beam scheduling mode of the signal processing system, interrupt the background search beam in the sector scan tracking mode, and concentrate all beams within a certain range of the tracking target to achieve search re-completion. Step S6: Based on the target loss result output by S5, the target track is cleared from the track display interface, the radar re-enters the mechanical scan search mode, the servo turntable starts to rotate at a constant speed, and the radar stops working after receiving the end scan command; otherwise, it continues to work in the mechanical scan search mode.

2. The method according to claim 1, characterized in that, In step S2, the target position prediction uses the Kalman filter algorithm, and the formula for calculating the angle deviation Δθ is Δθ = θ pred -θ mech , where θ pred To predict the azimuth of the target, θ mech This is the azimuth angle of the current servo turntable.

3. The method according to claim 1, characterized in that, The sector scan tracking mode in step S4 specifically includes: setting the radar scheduling period T. frame Allocate resources to search task (α) t ,β t ) and tracking task T trace The beam pointing and beamwidth of the tracking beam are calculated based on the covariance matrix of the target trajectory, and the antenna beam is controlled to point towards the target through a phase shifter. If there are multiple tracking targets, the tracking beams are prioritized and inserted according to their threat level.

4. The method according to claim 1, characterized in that, Step S5 specifically includes: setting the loss counter C lost The initial value is 0; if no echo exceeding the threshold is detected at the direction of the tracking beam, then C lost =C lost +1; if C lost If M < C, the radar maintains the current sector scan tracking mode and expands the gate of the tracking beam at the next moment; if M ≤ C lost <N, the radar switches to sector scan search mode, searching within ±Δφ of the target's last vanishing point to achieve search re-completion; if C lost If the value is ≥N, the target is determined to be completely lost. The servo turntable is controlled to resume rotation, and the radar switches back to mechanical scanning search mode.

5. A phased array radar fast switching tracking system based on target trajectory, characterized in that, include: Phased array antenna system: used to transmit and receive electromagnetic waves, supporting electronic beam scanning; Servo turntable system: used to support the mechanical rotation of phased array antennas; Signal processing system: used to control antenna transmission and reception timing, servo turntable control, and to process echo signals; Data processing system: used for functions such as track initiation, filtering and tracking, and coordinate transformation; Radar control terminal: used to set and adjust radar parameters and switch modes; Track display interface: used to display radar system status, track display, and target attribute identification, etc.

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