CN218547353U - Obstacle system is kept away in anticollision based on unmanned aerial vehicle - Google Patents
Obstacle system is kept away in anticollision based on unmanned aerial vehicle Download PDFInfo
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Abstract
The utility model provides a barrier system is kept away in anticollision based on unmanned aerial vehicle, the linear frequency modulation source provides asymmetric triangular wave as the transmitted signal, effectively reduce the system bandwidth of receiving the link, improve the sensitivity of receiving the link, reduce the noise coefficient of receiving the link, the beat signal that balanced mixer produced is converted to the frequency domain by FFT digital processing ware after the intermediate frequency is enlargied and is carried out the analysis, can avoid the time domain aliasing, the modulus ware is solved the mould to data and is handled, improve data processing speed, non-coherent accumulator carries out non-coherent accumulation to each signal amplitude, improve the SNR of weak signal, the distance signal that the constant false alarm detector detected out the barrier with the maximum probability in the target signal that thoughtlessly has mixed clutter interference, improve the accuracy, the utility model discloses the processing of transmission to the beat signal from the signal source has all optimized, provide accurate and the distance information of barrier for unmanned aerial vehicle, improved the performance that the anticollision kept away the barrier greatly, thereby improve the reliability that unmanned aerial vehicle operated.
Description
Technical Field
The utility model relates to an unmanned air vehicle technique field, especially obstacle avoidance system based on unmanned aerial vehicle's anticollision.
Background
Geological disasters including landslide, debris flow, ground subsidence and the like threaten life safety and property safety and hinder economic development and social stability. In order to reduce the negative effects of geological disasters, systems have been developed in the prior art that utilize unmanned aerial vehicles to accomplish the detection of geological disasters. Unmanned aerial vehicle flies at complicated changeable field environment, and the ability of obstacle is kept away in the anticollision is especially important.
In the detection process, the unmanned aerial vehicle is easily influenced by woods, flying birds, weather changes and sudden obstacles to interrupt the detection task. The problem of obstacle performance is kept away in the anticollision to promoting unmanned aerial vehicle, prior art sets up the ultrasonic sensor of different quantity, different positions, different orientation at unmanned aerial vehicle's fuselage for improve the accuracy of distance detection, but ultrasonic sensor has the requirement to the material of barrier, surface texture, the existence of barrier is uncertain not unique under the complicated changeable field environment, the easy wrong detection that appears, the condition of missing to survey and postponing the detection, influence the reliability of unmanned aerial vehicle operation.
SUMMERY OF THE UTILITY MODEL
The utility model provides an obstacle system is kept away in anticollision based on unmanned aerial vehicle, the problem that unmanned aerial vehicle operational reliability is low for solving the prior art existence provides hardware support.
The utility model discloses a technical problem is solved to following technical scheme:
the collision avoidance system based on the unmanned aerial vehicle comprises a distance detection module and a signal processing module;
the distance detection module comprises a linear frequency modulation source, a frequency multiplier, a power divider, a power amplifier, a transmitting antenna, a receiving antenna, a low noise amplifier, a balanced mixer, a band-pass filter and an intermediate frequency amplifier;
the output end of the linear frequency modulation source is connected with the input end of the frequency multiplier; the output end of the frequency multiplier is connected with the input end of the power divider; one output end of the power divider is connected with the input end of the power amplifier; the output end of the power amplifier is connected with the transmitting antenna; the signal sent by the transmitting antenna is reflected after meeting an external obstacle to generate an echo signal; the receiving antenna receives the echo signal and inputs the echo signal to the low noise amplifier; the output end of the low-noise amplifier is connected with one input end of the balanced mixer, the other output end of the power divider is connected with the other input end of the balanced mixer, and the output end of the balanced mixer is connected with the input end of the band-pass filter; the output end of the band-pass filter is connected with the input end of the intermediate frequency amplifier; the output end of the intermediate frequency amplifier is connected with the signal processing module;
the signal processing module comprises an analog-to-digital converter, an FFT digital processor, a modulus value device, a non-coherent accumulator and a constant false alarm detector;
the input end of the analog-to-digital converter is connected with the output end of the intermediate frequency amplifier, and the output end of the analog-to-digital converter is connected with the input end of the FFT digital processor; the output end of the FFT digital processor is connected with the input end of the modulus value device; the output end of the modulus value device is connected with the input end of the non-coherent accumulator; the output end of the non-coherent accumulator is connected with the input end of the constant false alarm detector; the output end of the constant false alarm detector is connected with an external flight control system.
Further, the linear frequency modulation source comprises a controller, a crystal oscillator, a loop filter, a frequency synthesizer and a micro-strip band-pass filter; the output end of the crystal oscillator is connected with one input end of the frequency synthesizer; the controller is connected with the other input end of the frequency synthesizer, the frequency synthesizer is connected with the loop filter in a two-way mode, and the output end of the frequency synthesizer is connected with the input end of the frequency multiplier through the microstrip band-pass filter.
Further, the bandwidth of the linear frequency modulation source is greater than or equal to 180MHz.
Further, the modulation period of the linear frequency modulation source is 300 μ s.
Further, the up-down frequency sweep modulation slope ratio of the linear frequency modulation source is 5:1.
The utility model has the advantages and effects that:
the transmitting link of the distance detection module provides asymmetric triangular waves as transmitting signals, the system bandwidth of the receiving link can be effectively reduced, the sensitivity of the receiving link is improved, the noise coefficient of the receiving link is reduced, a linear frequency modulation source acquires required frequency bands through combination with a frequency multiplier, the requirements of high sampling rate and high data rate can be met, echo signals and the transmitting signals are mixed to obtain beat signals, the beat signals are converted into frequency domains for analysis through an FFT (fast Fourier transform algorithm) digital processor after being amplified at intermediate frequency, time domain aliasing can be avoided, a modulus device carries out modulus processing on the data, the data processing speed can be improved, a non-coherent accumulator carries out non-coherent accumulation on signal amplitude, the signal-to-noise ratio of weak signals can be improved, a constant false alarm detector detects distance signals of obstacles in a target signal mixed with clutter interference at the maximum probability, the accuracy can be improved, the utility model discloses the processing from the transmitting of a signal source to the beat signals is optimized, accurate distance information from the obstacles is provided for an unmanned aerial vehicle, the performance of preventing collision and avoiding obstacles is greatly improved, and the reliability of the unmanned aerial vehicle operation is provided with hardware support.
Drawings
Fig. 1 is a schematic block diagram of the structure of the present invention.
Fig. 2 is a schematic block diagram of the structure of a linear frequency modulation source.
Detailed Description
The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples.
The unmanned aerial vehicle device comprises a posture recognition system, an anti-collision obstacle avoidance system, a flight control system and an execution system. The gesture recognition system generally includes modules such as an accelerometer, a gyroscope, a magnetometer, and a barometer, and is used for acquiring the gesture and the height of the drone body. Obstacle system is kept away in anticollision includes distance detection module and signal processing module usually for survey the distance of unmanned aerial vehicle body and barrier. The flight control system generally comprises an embedded module and a ground station, is used for processing data of the attitude recognition system and the anti-collision obstacle avoidance system, sends an instruction to the execution system after analysis and processing, and controls the attitude and the course of the unmanned aerial vehicle body through the execution system.
The utility model provides an anticollision obstacle avoidance system based on unmanned aerial vehicle, including distance detection module and signal processing module; the distance detection module comprises a linear frequency modulation source, a frequency multiplier, a power divider, a power amplifier, a transmitting antenna, a receiving antenna, a low noise amplifier, a balanced mixer, a band-pass filter and an intermediate frequency amplifier; the output end of the linear frequency modulation source is connected with the input end of the frequency multiplier; the output end of the frequency multiplier is connected with the input end of the power divider; one output end of the power divider is connected with the input end of the power amplifier; the output end of the power amplifier is connected with the transmitting antenna; the signal sent by the transmitting antenna is reflected after meeting an external obstacle to generate an echo signal; the receiving antenna receives the echo signal and inputs the echo signal to the low noise amplifier; the output end of the low noise amplifier is connected with one input end of the balanced mixer, the other output end of the power divider is connected with the other input end of the balanced mixer, and the output end of the balanced mixer is connected with the input end of the band-pass filter; the output end of the band-pass filter is connected with the input end of the intermediate frequency amplifier; the output end of the intermediate frequency amplifier is connected with the signal processing module; the signal processing module comprises an analog-to-digital converter, an FFT digital processor, a modulus value device, a non-coherent accumulator and a constant false alarm detector; the input end of the analog-to-digital converter is connected with the output end of the intermediate frequency amplifier, and the output end of the analog-to-digital converter is connected with the input end of the FFT digital processor; the output end of the FFT digital processor is connected with the input end of the modulus value device; the output end of the modulus value device is connected with the input end of the non-coherent accumulator; the output end of the non-coherent accumulator is connected with the input end of the constant false alarm detector; and the output end of the constant false alarm detector is connected with an external flight control system. The structure and the schematic block diagram of the present invention are shown in fig. 1.
The linear frequency modulation source comprises a controller, a crystal oscillator, a loop filter, a frequency synthesizer and a micro-strip band-pass filter; the output end of the crystal oscillator is connected with one input end of the frequency synthesizer; the controller is connected with the other input end of the frequency synthesizer, the frequency synthesizer is connected with the loop filter in a two-way mode, and the output end of the frequency synthesizer is connected with the input end of the frequency multiplier through the microstrip band-pass filter. The structural schematic block diagram of the linear frequency modulation source is shown in fig. 2.
The crystal oscillator provides reference frequency for the frequency synthesizer, synthesizes and considers phase noise and frequency degree of divergence, the utility model discloses crystal oscillator's frequency selection 50MHz. The frequency synthesizer is a broadband frequency synthesizer and generates a linear asymmetric triangular wave under the control of the controller. The loop filter is a third-order loop filter and is used for attenuating phase errors and filtering high-frequency components. The microstrip band-pass filter is used for realizing radio frequency filtering and inhibiting broadband frequency stray.
The chirp source can provide the chirp continuous wave, the utility model discloses an asymmetric triangular wave is as the transmitted signal, and this type's detected signal has the characteristics that no distance blind area and sensitivity are high, and under the certain condition of target distance, the modulation slope is big more, beat frequency is big more, the bandwidth of receiving link is just narrower more, just also means that the sensitivity of receiving link is high more, and noise figure is low more, just also can wholly improve the detection sensitivity and the detection degree of accuracy of apart from detection module.
The distance resolution represents the capability of distinguishing two close-range targets, and the optimal distance resolution can be obtained through the appropriate modulation bandwidth. Even if the receiving link of the distance detection module does not receive the echo signal, the frequency output can be modulated by the mixer, namely, the spurious amplitude modulation exists, and the influence of the spurious amplitude modulation can be reduced as far as possible by the proper modulation bandwidth. Researches show that when the modulation bandwidth of the linear frequency modulation source is larger than or equal to 180MHz, the distance resolution is smaller than 1, when the modulation bandwidth is 200MHz, the distance resolution is optimal and is 0.75, and the influence on parasitic amplitude modulation is minimum.
The signal transmitted by the transmitting antenna is reflected after meeting obstacles to generate an echo signal, the receiving antenna receives the echo signal, and the echo signal and the transmitting signal are mixed to obtain a beat signal. Under the condition that the obstacle distance is constant, the larger the modulation slope is, the larger the beat frequency is. Because the beat signal has an irregular area, the analog-to-digital converter needs to avoid the irregular area in order to obtain more accurate beat frequency, but avoiding the irregular area can reduce the number of sampling points of the analog-to-digital converter, and the accuracy of the detection distance is influenced. It has been found that the accuracy of the detection range is highest only in the case where the modulation period is much larger than the echo delay. Therefore, the modulation period of the linear frequency modulation source of the present invention is selected to be 300 μ s, and the modulation slope ratio of the up-down frequency sweep is selected to be 5:1.
The more the frequency doubling quantity of the frequency multiplier is, the less pure the frequency spectrum is, the higher the phase noise and the frequency impurity degree are, and the frequency multiplier should be controlled to be used as much as possible. The utility model discloses according to the detection demand, use 2 times frequency multiplier to realize Ka wave band frequency output.
The power divider is a two-path power divider, and divides one path of input signal energy into two paths of equal signal energy, wherein one path of input signal energy is input to the power amplifier for power amplification and then transmitted by the transmitting antenna, and the other path of input signal energy is input to the balanced mixer for serving as a local oscillation signal.
Received echo signal of receiving antenna is comparatively faint, need carry out preamplification, the utility model discloses use low noise amplifier to enlarge this echo signal, low noise amplifier's advantage can also restrain self noise when enlargiing echo signal, avoids bringing the interference for the signal processing in later stage.
The frequency components generated during the shifting of the mixer are many, and parasitic amplitude modulation can be generated even under the condition that no echo signal exists. The balanced mixer has the advantage that the conversion loss is low and the isolation is high for ordinary mixer, consequently, the utility model discloses use balanced mixer to accomplish the frequency spectrum and move to reduce parasitic amplitude modulation's influence.
The band-pass filter is a circuit which allows waves in a specific frequency band to pass through and shields other frequency bands, and intermediate frequency beat signals output by the balanced mixer are input to the intermediate frequency amplifier for amplification after clutter is filtered by the band-pass filter, so that subsequent signal processing is facilitated.
The working process of the distance detection module is as follows: the method comprises the steps that a linear frequency modulation source generates asymmetric triangular waves, 2 times of frequency multiplication is carried out through a frequency multiplier to obtain a frequency modulation signal of a Ka wave band, the frequency modulation signal is subjected to power division to obtain 2 paths of signals, one path of signal is amplified through a power amplifier and then is transmitted out through a transmitting antenna, the other path of signal is input into a balanced frequency mixer to serve as a local oscillation signal, the transmitted frequency modulation signal is reflected after encountering an obstacle to obtain an echo signal, the echo signal is received through a receiving antenna and is amplified through a low-noise amplifier and then is sent into the balanced frequency mixer to be mixed with the local oscillation signal to obtain an intermediate frequency beat signal, and the intermediate frequency beat signal is filtered through a band-pass filter, amplified through an intermediate frequency amplifier and then sent into a signal processing module.
The signal output by the distance detection module is an analog signal, the analog-to-digital converter of the signal processing module performs analog-to-digital conversion to obtain a corresponding digital signal, and then the digital signal is input to the FFT digital processor.
The FFT digital processor, namely the fast Fourier transform digital processor, has the capacity of processing digital signals, carries out fast Fourier transform on the digital signals output by the analog-to-digital converter to obtain a frequency domain graph, can obtain the distance information of the obstacles according to the frequency domain graph, and can avoid time domain aliasing.
And the modulus value device performs modulus processing on the output signal of the FFT digital processor to obtain an amplitude value. The modulus device mainly comprises a multiplier, an adder and a square root device. The modulus device multiplies and divides the data bits of the FFT digital processor, thereby greatly reducing the data bits, improving the data processing speed and not influencing the accuracy of data processing.
The non-coherent accumulator performs non-coherent accumulation on each signal amplitude value until accumulation of a plurality of signal periods is completed, so that the signal-to-noise ratio of the weak signal is improved, and the accuracy of distance detection is improved.
The constant false alarm detector detects the non-coherent accumulated data by adopting a constant false alarm detection method to obtain a target distance signal, and detects the distance signal of the obstacle in the beat signal mixed with clutter interference according to the maximum probability.
The working process of the signal processing module comprises the following steps: the intermediate frequency beat signal output by the distance detection module is input to an analog-to-digital converter for analog-to-digital conversion to obtain a digital signal, the digital signal is input to an FFT digital processor by the analog-to-digital converter to obtain a frequency domain diagram containing obstacle distance information, the information of the frequency domain diagram is input to a modulus value device for modulus processing, then non-coherent accumulation is carried out by a non-coherent accumulator, then a distance signal of an obstacle is obtained by a constant false alarm detector with the maximum probability, the distance signal is input to an external flight control system, and an execution system is controlled by the external flight control system to adjust the posture and the course of the unmanned aerial vehicle.
In the electrical field, data detection, data transmission, data processing, control and execution of instructions necessarily involve computer programs, and if the computer programs involved are prior art, external programs or simple calculations, comparisons and controls, the technical solutions should not be considered as involving improvements in the computer programs. The utility model discloses in, it provides hardware support to have clearly shown in the description that this technical scheme is the problem that the unmanned aerial vehicle operational reliability is low for solving prior art existence, namely, only make contributions on the hardware for solving corresponding technical problem, can know from beneficial effect's analysis, the optimization through hardware among the technical scheme has reduced the bandwidth of receiving link, the sensitivity of receiving link is provided, the noise figure of receiving link has been reduced, the time domain aliasing has been avoided, the signal to noise ratio of weak signal has been improved, the accuracy of distance detection has been improved etc., and, also correspondingly only apply for the corresponding hardware of protection in the claim, do not have the improvement of computer program, therefore, the utility model discloses should not think that fall into the protection category of unauthorized object.
Claims (5)
1. Obstacle system is kept away in anticollision based on unmanned aerial vehicle, its characterized in that:
the device comprises a distance detection module and a signal processing module;
the distance detection module comprises a linear frequency modulation source, a frequency multiplier, a power divider, a power amplifier, a transmitting antenna, a receiving antenna, a low noise amplifier, a balanced mixer, a band-pass filter and an intermediate frequency amplifier;
the output end of the linear frequency modulation source is connected with the input end of the frequency multiplier; the output end of the frequency multiplier is connected with the input end of the power divider; one output end of the power divider is connected with the input end of the power amplifier; the output end of the power amplifier is connected with the transmitting antenna; the signal sent by the transmitting antenna is reflected after encountering an external obstacle to generate an echo signal; the receiving antenna receives the echo signal and inputs the echo signal to the low noise amplifier; the output end of the low-noise amplifier is connected with one input end of the balanced mixer, the other output end of the power divider is connected with the other input end of the balanced mixer, and the output end of the balanced mixer is connected with the input end of the band-pass filter; the output end of the band-pass filter is connected with the input end of the intermediate frequency amplifier; the output end of the intermediate frequency amplifier is connected with the signal processing module;
the signal processing module comprises an analog-to-digital converter, an FFT digital processor, a modulus value device, a non-coherent accumulator and a constant false alarm detector;
the input end of the analog-to-digital converter is connected with the output end of the intermediate frequency amplifier, and the output end of the analog-to-digital converter is connected with the input end of the FFT digital processor; the output end of the FFT digital processor is connected with the input end of the modulus value device; the output end of the modulus value device is connected with the input end of the non-coherent accumulator; the output end of the non-coherent accumulator is connected with the input end of the constant false alarm detector; and the output end of the constant false alarm detector is connected with an external flight control system.
2. The unmanned aerial vehicle-based collision avoidance system of claim 1, wherein:
the linear frequency modulation source comprises a controller, a crystal oscillator, a loop filter, a frequency synthesizer and a micro-strip band-pass filter;
the output end of the crystal oscillator is connected with one input end of the frequency synthesizer; the controller is connected with the other input end of the frequency synthesizer, the frequency synthesizer is connected with the loop filter in a two-way mode, and the output end of the frequency synthesizer is connected with the input end of the frequency multiplier through the microstrip band-pass filter.
3. The unmanned aerial vehicle-based collision avoidance system of claim 2, wherein: the bandwidth of the linear frequency modulation source is larger than or equal to 180MHz.
4. The unmanned aerial vehicle-based collision avoidance system of claim 2, wherein: the modulation period of the linear frequency modulation source is 300 μs 。
5. The unmanned aerial vehicle-based collision avoidance system of claim 2, wherein: the up-down frequency sweep modulation slope ratio of the linear frequency modulation source is 5:1.
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