Radar target simulation method and device based on linear track and turntable

Abstract

The present invention discloses a radar target simulation method and device based on a linear track and a turntable. The difference from the prior art is mainly reflected in that the transmitting antenna of the simulator is fixed on a turntable that can rotate in azimuth, and the turntable is made to perform lateral linear motion relative to the radar to achieve the simulation of the target azimuth angle. The turntable also performs its own rotational motion while performing linear motion, and ensures in real time that the main lobe of the simulator transmitting antenna always points to the phase center of the radar receiving antenna. The method of the present invention can expand the distance between the simulator transmitting antenna and the radar, and meet the far-field conditions of the radar angle test. At the same time, the linear track has the advantages of easy processing, high precision and low cost.

Description

Technical Field

[0001] The invention relates to a radar target simulation method and equipment based on a linear track and a turntable, and belongs to the field of radar testing. Background Art

[0002] With the rapid development of assisted driving and autonomous driving, the demand for vehicle-mounted millimeter-wave radar is increasing day by day. Radars require target simulators during research and development and mass production testing. Existing target simulators generally use circular arc tracks for angle simulation, that is, the simulator's transmitting antenna is placed on a circular arc track with the radar as the center to move, thereby completing the simulation of the target's azimuth angle, and the distance simulation relies on the simulator's delay function. Due to the difficulty and high cost of processing large-radius circular arc tracks, and the relatively low angular velocity of circular motion, it is difficult to simulate high-speed lateral moving targets. The larger the arc radius, the slower the angular velocity of movement. Existing technologies can only achieve small-radius circular arc tracks, which are difficult to meet the requirements of radar far-field test conditions.

[0003] The automotive radar angle test requires that the distance between the radar and the simulator must meet the far-field conditions. For the automotive radar frequency band, it generally needs to reach more than 4m. Existing simulators are difficult to meet the far-field distance requirements. Summary of the invention

[0004] According to the present invention, the mechanical slide rail technology is still used to simulate the azimuth angle, and a turntable is designed on a straight track to replace the existing arc track technology, so that the distance between the simulator and the radar meets the far-field condition.

[0005] The present invention proposes a radar target simulation method based on a linear track and a turntable, wherein the method comprises: fixing the transmitting antenna of the simulator on a turntable which can rotate in azimuth, allowing the turntable to perform lateral linear motion relative to the radar to achieve simulation of the target azimuth angle, and the turntable also performs its own rotational motion while performing linear motion, so as to ensure in real time that the main lobe of the simulator transmitting antenna always points to the phase center of the radar receiving antenna.

[0006] Preferably, the phase center of the simulator transmitting antenna is fixed on the axis of the turntable.

[0007] Preferably, the linear motion has a position coordinate R a The calculation formula is as follows:

[0008] R a =R0tgθ

[0009] Among them, R a is the shortest distance between the axis of the turntable and the radar normal direction, R0 is the shortest distance between the radar receiving antenna and the simulator transmitting antenna, and θ is the azimuth angle of the current simulated target.

[0010] Preferably, the azimuth angle control amount β of the rotational movement of the turntable itself is equal to the azimuth angle θ of the current simulated target.

[0011] Preferably, the simulator needs to compensate the target distance change caused by the linear motion in real time during the simulation process, and the distance compensation amount ΔR is calculated as follows:

[0012]

[0013] Among them, ΔR is the distance compensation, R0 is the closest distance between the radar receiving antenna and the simulator transmitting antenna, and θ is the azimuth angle of the current simulated target.

[0014] Preferably, the simulator needs to compensate in real time during the simulation process for changes in the RCS size of the simulated target caused by changes in the physical distance between the radar receiving antenna and the simulator transmitting antenna. The simulator has an amplitude compensation coefficient α for the transmitted signal. A The calculation formula is as follows:

[0015]

[0016] Among them, θ is the azimuth angle of the current simulated target.

[0017] Preferably, the simulator needs to compensate in real time during the simulation process for the change in the Doppler size of the simulated target caused by the change in the physical distance between the radar receiving antenna and the simulator transmitting antenna. The simulator compensates for the Doppler of the simulated target, and the size of the compensated Doppler Δf d The calculation formula is as follows:

[0018]

[0019] Where v is the speed of the simulated target, R0 is the closest distance between the radar receiving antenna and the simulator transmitting antenna, R is the distance value of the simulated target, θ v is the angle between the target velocity direction and the radar normal direction, θ is the azimuth angle of the current simulated target, and λ is the wavelength corresponding to the center frequency of the transmitted signal.

[0020] The present invention also proposes a radar target simulation device based on a linear track and a turntable, wherein the device implements the radar target simulation device as described above.

[0021] According to the present invention, the distance between the simulator transmitting antenna and the radar can be expanded to meet the far-field condition of the radar angle test, and the straight track is easy to process with high precision and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : It is a principle block diagram of the prior art;

[0023] Figure 2 : is a principle block diagram of the method of the present invention;

[0024] Figure 3 : It is a principle block diagram of feasibility analysis of the method of the present invention;

[0025] Figure 4 :Block diagram of 77GHz band radar target simulator system. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] The embodiment of the method of the present invention is as follows:

[0028] According to the present invention, a radar target simulation method based on a linear track and a turntable is proposed, which completely retains all the hardware and software frameworks of the existing simulator, except that the circular arc track is replaced by a linear track and a turntable. Figure 1 The figure shows the principle block diagram of the mechanical part of the existing simulation technology. In the existing technology, the transmitting antenna of the simulator is fixed on the arc mover, and the arc mover moves on the arc track with the radar as the center, so as to complete the simulation of the target azimuth angle. Figure 2 The mechanical part of the method of the present invention is a block diagram. Figure 2 The main difference from the existing technical features is the use of a linear track and a turntable. The simulator's transmitting antenna is fixed on a turntable that can rotate in azimuth, and the turntable makes a lateral linear motion relative to the radar to simulate the target azimuth angle. The turntable also makes its own rotational motion while moving in a linear motion, ensuring in real time that the main lobe of the simulator's transmitting antenna always points to the radar's antenna phase center.

[0029] The target simulation process of the prior art is as follows: the receiving antenna obtains the radar transmission signal, and the intermediate frequency signal is obtained through the down-conversion module. After the distance and speed are modulated, it passes through the up-conversion module and then radiated to the radar by the transmitting antenna to complete the simulation of the target distance and speed. By placing the transmitting antenna on an arc track with the radar as the center, the arc movement of the transmitting antenna is realized through motor control, thereby completing the target azimuth angle simulation function.

[0030] According to the present invention, the receiving antenna obtains the radar transmission signal, obtains the intermediate frequency signal through the down-conversion module, modulates the distance and speed, passes through the up-conversion module, and then radiates to the radar through the transmitting antenna to complete the simulation of the target distance and speed. The transmitting antenna of the simulator is fixed on a turntable that can rotate in azimuth, and the turntable is made to perform lateral linear motion relative to the radar to achieve the simulation of the target azimuth angle. The position coordinates of the linear motion are R a The calculation formula is R a=R0tgθ. In order to achieve this goal, when fixing the transmitter antenna, ensure that the phase center of the simulator transmitting antenna is fixed on the axis of the turntable, and ensure that the phase center of the antenna always makes precise linear motion during the rotation of the turntable.

[0031] The turntable also rotates while moving linearly, ensuring that the main lobe of the simulator's transmitting antenna always points to the radar's antenna phase center. To achieve this goal, the turntable azimuth angle control value β is equal to the azimuth angle θ of the current simulated target.

[0032] When the simulated target control quantity is the azimuth angle θ and the distance R, the simulation of the azimuth angle has been accurately completed under the above mechanical motion control. However, due to the linear slide rail, the movement of the simulator's transmitting antenna phase center is a lateral linear motion relative to the radar, so the distance of the simulated target has changed. This is a unique problem of the linear track. In order to ensure the accuracy of the simulated target distance, it is necessary to compensate for the target distance change caused by the linear motion in real time. The distance compensation amount ΔR is calculated as follows:

[0033]

[0034] Among them, ΔR is the distance compensation amount, R0 is the closest distance between the radar receiving antenna and the simulator transmitting antenna, and θ is the azimuth angle of the current simulated target. After compensation, accurate simulation of the target distance can be achieved.

[0035] When the simulated target control quantity is the azimuth angle θ and the distance R, under the above mechanical motion control, the phase center of the simulator's transmitting antenna changes relative to the actual physical distance of the radar, which will cause the simulated target RCS size to change. With the closest distance as a reference, all positions will cause RCS attenuation. Therefore, in order to accurately simulate the target RCS, the simulator needs to compensate the amplitude of the transmitted signal by directly multiplying it by the compensation coefficient α A =1 / cos 2 θ, after compensation, the accurate simulation of the target RCS can be achieved.

[0036] When the simulated target control quantity is the azimuth angle θ and the distance R, under the above mechanical motion control, the phase center of the simulator's transmitting antenna changes relative to the actual physical distance of the radar, which will cause the magnitude of the simulated target's radial velocity to change. Therefore, in order to accurately simulate the magnitude of the target's radial velocity, the simulator needs to compensate the Doppler of the simulated target. The magnitude of the compensated Doppler is After compensation, accurate simulation of the target radial velocity can be achieved.

[0037] The applicable conditions of the embodiment of the method of the present invention are described below.

[0038] Since the method of the present invention only improves the design of the mechanical device part of the simulator system, and only controls the distance compensation and the transmission signal strength of the simulator signal part, and does not cause additional additional use conditions, the applicable conditions are wide.

[0039] Combine the following Figure 3 The feasibility of the method of the present invention is analyzed.

[0040] according to Figure 3 , the target distance that the simulator needs to simulate is R, the speed is v, the angle is θ, the RCS size is σ, the radar is located at point O, the OO′ line is the radar normal direction, and point O′ is the vertical intersection of the radar normal and the center line of the linear motion. The target is located at point B, and the angle between the motion direction and the radar normal direction is θ v , is the velocity vector. The vertical distance between the radar and the center line of the linear motion is OO′=R0.

[0041] In order to complete the simulation of the target angle θ, the simulator needs to fix the phase center of the transmitting antenna at point A. Point A is the intersection of the OB line and the center line of the linear motion. The geometric relationship ensures that ∠AOO′=θ, thereby completing the angle simulation.

[0042] In order to complete the simulation of the target distance R, the simulator needs to compensate for the change in the physical distance between the radar and the simulator. Here, it is assumed that the simulator is calibrated for distance O′. When the target moves to point A, the physical distance between the radar and the phase center of the simulator's transmitting antenna changes from R0 to R0 / cosθ, and the simulated target distance is R+R0(1 / cosθ-1). When the compensation amount ΔR=-R0(1 / cosθ-1), the final simulated target distance is R.

[0043] In order to complete the simulation of the target RCS, the simulator needs to compensate for the size change caused by the change in the physical distance between the radar and the simulator. Here, it is assumed that the simulator is calibrated for the RCS size at point O′. When the target moves to point A, the physical distance between the radar and the simulator's transmitting antenna phase center changes from R0 to R0 / cosθ. The target RCS size is set to σ, and the simulated RCS size without compensation is σ·cos 2 θ, when the compensation coefficient α A =1 / cos 2 When θ is equal to 0, the accurate simulation of the set RCS size σ is completed.

[0044] In order to complete the simulation of the target speed v, the simulator needs to compensate for the Doppler magnitude change caused by the change in the physical distance between the radar and the simulator. Assuming the target's moving speed at point B is v, the equivalent moving speed to point A is The direction is from point A to point D. Since the simulator antenna can only move in a straight line, in order to complete the angle simulation, the physical movement speed of the simulator in the straight line is v AD The projection on the straight line is The Doppler magnitude caused by this physical motion is When the Doppler size of the compensated simulated target is , the precise simulation of the set target speed v is completed.

[0045] The above analysis shows that it is feasible for the simulator to accurately simulate the target distance, speed, angle, and RCS.

[0046] Device embodiment 1 of the present invention: 77 GHz frequency band radar dual-target simulation device.

[0047] The system composition and application diagram of the 77GHz frequency band radar target simulator are as follows: Figure 4 The device of the present invention comprises: a DRFM simulator host device, a receiving antenna and a radio frequency module, a transmitting antenna and a radio frequency module 1, a transmitting antenna and a radio frequency module 2, a turntable and a linear motion control module, a turntable and a mover module 1, a turntable and a mover module 2, and a linear slide assembly.

[0048] Among them, there is a DRFM simulator host device, including: a DRFM simulator system control center, a signal modulation module, an intermediate frequency transmission signal module 1, an intermediate frequency transmission signal module 2, and an intermediate frequency receiving signal module. The DRFM simulator system control center is used for the overall operation control of the entire simulator system, including providing users with target information setting, displaying target information, and real-time monitoring of the target simulation process. The distance, speed, angle, and RCS information of the two targets to be simulated are calculated by the method of the present invention to obtain the compensated distance, speed, and RCS information, which are sent to the signal modulation module. The signal modulation module completes the modulation of the two-way target information and outputs it to the intermediate frequency transmission signal module 1 and the intermediate frequency transmission signal module 2 respectively. These two modules complete the first level of up-conversion, filtering and amplification processing, change the center frequency of the signal from 1GHz to 10GHz, and send the signal to the RF antenna and RF module 1 and the RF antenna and RF module 2 respectively. The intermediate frequency receiving signal module receives the 10GHz intermediate frequency signal output by the receiving antenna and the RF module, and enters the signal modulation module after filtering and amplification.

[0049] The turntable and linear motion control module communicates with the DRFM simulator system control center, receives the target information transmitted in real time from the DRFM simulator system control center, obtains the turntable control information and linear mover control information of target 1 and target 2 through calculation, and sends them to turntable and mover module 1 and turntable and mover module 2 respectively. Turntable and mover module 1 includes turntable direct drive motor 1, turntable 1, and linear motor mover 1. Turntable and mover module 2 includes turntable direct drive motor 2, turntable 2, and linear motor mover 2.

[0050] The linear guide rail components mainly include: linear motor stator and linear guide rail, various motor drivers, electronic control components, and power modules.

[0051] The receiving antenna and RF module are placed at the normal line of the radar, slightly lower than the transmitting antenna and RF module, to ensure that they do not block the transmitting antenna. The receiving antenna and RF module receive the radar transmission signal, down-convert it to a center frequency of 10 GHz, and then output it to the intermediate frequency receiving signal module through the RF cable.

[0052] The transmitting antenna and RF module 1 receive the 10GHz center frequency signal output by the intermediate frequency transmitting signal module 1, complete the second-level up-conversion and filtering, amplification processing of the target 1 signal, and radiate it to the radar. The transmitting antenna and RF module 1 are fixed on the turntable 1 to ensure that the phase center of the transmitting antenna is located on the axis of the turntable 1, so that when the turntable rotates and moves linearly, the phase center of the transmitting antenna always moves linearly. The turntable 1 is fixed on the mover module 1, receives the turntable control information transmitted in real time by the turntable and the linear motion control module, and ensures that the main lobe of the simulator transmitting antenna 1 always points to the radar in real time. This step ensures the accuracy of the RCS simulation of target 1. The mover module 1 receives the linear motion control information transmitted in real time by the turntable and the linear motion control module, completes the linear motion on the linear guide rail, and ensures the accuracy of the angle simulation of target 1.

[0053] The transmitting antenna and the RF module 2 receive the 10GHz center frequency signal output by the intermediate frequency transmitting signal module 2, complete the second-level up-conversion and filtering and amplification processing of the target 2 signal, and radiate it to the radar. The transmitting antenna and the RF module 2 are fixed on the turntable 2 to ensure that the phase center of the transmitting antenna is located on the axis of the turntable 2, so that when the turntable rotates and moves linearly, the phase center of the transmitting antenna always moves linearly. The turntable 2 is fixed on the mover module 2, receives the turntable control information transmitted in real time by the turntable and the linear motion control module, and ensures in real time that the main lobe of the simulator transmitting antenna 2 always points to the radar. This step ensures the accuracy of the RCS simulation of the target 2. The mover module 2 receives the linear motion control information transmitted in real time by the turntable and the linear motion control module, completes the linear motion on the linear guide rail, and ensures the accuracy of the angle simulation of the target 2.

[0054] In summary, the present invention provides a radar target simulation method and device based on a linear track and a turntable. The above is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. In fact, the present invention has no restrictions on the frequency band and bandwidth of the radar. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A radar target angle simulation method based on a linear track and a turntable, characterized in that: The method comprises: fixing the transmitting antenna of the simulator on a turntable which can rotate in azimuth, making the turntable perform lateral linear motion relative to the radar to achieve simulation of the target azimuth angle, and the turntable performs its own rotational motion while performing linear motion, so as to ensure in real time that the main lobe of the transmitting antenna of the simulator always points to the antenna phase center of the radar; The simulator needs to compensate the target distance change caused by linear motion in real time during the simulation process. The distance compensation ΔR is calculated as follows: Among them, ΔR is the distance compensation, R o is the shortest distance between the radar receiving antenna and the simulator transmitting antenna, and θ is the azimuth angle of the current simulated target; The simulator needs to compensate in real time for the change in the RCS size of the simulated target caused by the change in the physical distance between the radar receiving antenna and the simulator transmitting antenna during the simulation process. The simulator has an amplitude compensation coefficient α for the transmitted signal. A The calculation formula is as follows: Among them, θ is the azimuth angle of the current simulated target; During the simulation process, the simulator needs to compensate in real time for the change in the Doppler size of the simulated target caused by the change in the physical distance between the radar receiving antenna and the simulator transmitting antenna. The simulator compensates the Doppler of the simulated target by the size of the compensated Doppler Δf d The calculation formula is as follows: Where v is the speed of the simulated target, R o is the shortest distance between the radar receiving antenna and the simulator transmitting antenna, R is the distance value of the simulated target, θ v is the angle between the target velocity direction and the radar normal direction, θ is the azimuth angle of the current simulated target, and λ is the wavelength corresponding to the center frequency of the transmitted signal.

2. The radar target simulation method according to claim 1, wherein the phase center of the simulator transmitting antenna is fixed on the axis of the turntable.

3. The radar target simulation method according to claim 1, wherein the position coordinates R of the linear motion a The calculation formula is as follows: R a =R0tgθ in, R a is the shortest distance between the axis of the turntable and the radar normal direction, R0 is the shortest distance between the radar receiving antenna and the simulator transmitting antenna, and θ is the azimuth angle of the current simulated target.

4. The radar target simulation method according to claim 1, wherein the azimuth angle control amount β of the rotational motion of the turntable itself is equal to the azimuth angle θ of the current simulated target.

5. A radar target angle simulation device based on a linear track and a turntable, characterized in that: The device implements the radar target simulation method according to any one of claims 1 to 4.

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