262 results about "Doppler velocity" patented technology

The invention discloses a robot obstacle avoidance method and system based on millimeter wave radar sparse point cloud, and relates to the technical field of obstacle avoidance recognition. A robot obstacle avoidance system based on millimeter wave radar sparse point cloud comprises a point cloud acquisition module, a negative obstacle identification module, a weak obstacle identification module, a point cluster identification module, a risk map module, a tentative verification module and an obstacle avoidance decision module. According to the invention, suspected obstacle point clusters are extracted based on a reflection intensity threshold and a spatial proximity relation in an enhanced point cloud, a theoretical parallax model of a real static obstacle is constructed under the constraint of a robot motion trajectory, and Doppler velocity distribution of each frame is combined with a static obstacle Doppler physical law for comparison. And classifying the point clusters which do not meet the multi-view geometric consistency or Doppler physical law, and distinguishing multipath false point clusters from dynamic point clusters.

The invention discloses a heterogeneous sensor fusion method and system for dynamic covariance optimization, and the method comprises the steps: constructing a multi-source heterogeneous sensor network which comprises an underwater inertial navigation unit, a Doppler velocity sensor, an ultra-short baseline positioning system, a submarine topography matching device and a geomagnetic gradient detector; the method comprises the following steps: designing a distributed integrated navigation system by adopting a hierarchical fusion architecture, establishing a sensor confidence coefficient dynamic evaluation model based on online estimated error covariance matrix eigenvalue analysis, carrying out state prediction on a local filter level by applying Kalman filtering, and then carrying out measurement updating by adopting a novel variational Bayesian algorithm; a sensor autonomous switching and adaptive weighted dual-mode adjustment mechanism is developed on the main filter level, and self-healing improvement of navigation precision in a non-stationary environment is realized, so that the problems of dynamic reliability evaluation and fusion efficiency optimization in underwater multi-sensor multi-source navigation are solved.

The invention discloses a positioning processing method suitable for observation data under a GNSS complex condition. The positioning processing method comprises the following steps: step 1, setting residual check thresholds of a pseudo-range positioning observation value and a Doppler velocity observation value; step 2, on the basis of a residual check threshold of a pseudo-range positioning observation value, calculating an optimal estimated value of pseudo-range positioning observation and a corresponding variance-covariance matrix according to residual satellites for satellites with abnormal pseudo-range positioning observation values; step 3, based on a residual error test threshold value of the Doppler velocity observation value and a detection result in the step 2, eliminating satellites with abnormal Doppler velocity observation values, and calculating an optimal estimated value of Doppler velocity observation and a corresponding variance-covariance matrix according to the residual satellites; and step 4, updating the Kalman filtering state vector of the GNSS based on the results of the step 2 and the step 3. The method can improve the estimation precision of the initial values of the position and the speed, and further improves the positioning precision of the GNSS.

The present disclosure generally relates to methods, systems, apparatuses, and non-transitory computer readable media for processing radar signals of a MIMO radar system. By dynamically accounting for environmental noise both spatially and temporally, systems of the present disclosure can make radar-based systems more accurate and robust against noised-induced false detections, especially with respect to the use of sparse-receivers. More precisely, systems of the present disclosure may first process MIMO radar return data to identify one or more range-Doppler-elevation (RDE) bins exceeding a candidate detection criteria. Each identified candidate detection RDE bin may then be processed by a second search procedure to identify any azimuth bins (of the particular candidate detection RDE bin) exceeding a confirmed detection criteria. Each identified azimuth bin indicates a confirmed detection of a scatterer (e.g., an object) whose azimuth, elevation, range, and Doppler-velocity indicated by the identified azimuth bin and its associated candidate detection RDE bin.

The invention relates to the technical field of radar identification, and discloses a radar identification and collision early warning method and system for a two-wheeled vehicle, and the method comprises the steps: carrying out the synchronous collection of a radar echo signal and a vehicle body motion signal in a backward detection region of an electric two-wheeled vehicle, doppler frequency shift data, radar reflection sectional area data, radial distance data, reflection signal intensity data and motion state data are obtained; carrying out vehicle body motion compensation and time sequence variance calculation to obtain first static and dynamic target classification information; carrying out reflection characteristic calculation to obtain a candidate target data set; and performing consistency verification on the radial distance change rate and the Doppler velocity to obtain second static and dynamic target classification information, and outputting a target early warning signal in combination with the second static and dynamic target classification information. And the timeliness and reliability of collision early warning are improved.

The invention discloses a composite precipitation cloud layer identification method based on a laser radar-cloud radar, and the method comprises the steps: obtaining the observation data of the laser radar and the cloud radar, and carrying out the data matching of the observation data; processing a signal of the laser radar in a height interval of 18-20 km to obtain a preprocessed laser radar signal; performing laser radar cloud boundary identification based on a VED algorithm, and endowing different laser radar cloud scores according to the signal attenuation rate and the signal gradient; removing earth surface clutters by using a threshold method based on observation of spectral width and Doppler velocity; carrying out cloud radar significant echo recognition based on a threshold method, and determining the cloud score of the cloud radar according to different reflectivity factor signal intensities; determining a light rain area and a heavy rain area according to the Doppler velocity; cloud layer boundary information and a hairy rain area are obtained through cloud layer recognition result fusion, and cloud layer recognition and rainfall area recognition are completed; according to the invention, the accuracy of weather prediction is improved.

The invention discloses a bed load sediment transport rate measurement method based on multi-layer sediment acoustic signal attenuation correction of a Doppler velocity profiler, which comprises the following steps: sampling sediment on the surface of a riverbed in an overtopping area of a to-be-measured river reach, and measuring sediment gradation to obtain the median particle size of the bed sediment; obtaining flow measurement data, and extracting ship speed data from the flow measurement data; calculating a riverbed movement speed according to the ship speed data; filtering the riverbed movement speed data, and calculating a characteristic value of the filtered riverbed movement speed data; respectively calculating the vertical projection area ratio of bed load according to the filtered riverbed movement speed data characteristic values; calculating a dimensionless sediment particle size according to the median particle size of the bed sand; calculating the thickness of a bed load layer according to the dimensionless sediment particle size; calculating the volume concentration of the bed load according to the vertical projection area ratio of the bed load and the thickness of the bed load layer; calculating a multi-layer sediment sound signal attenuation correction coefficient according to the bed load volume concentration; and calculating the bed load sediment transport rate according to the multi-layer sediment sound signal attenuation correction coefficient. The bed load sediment transport rate can be accurately and effectively measured.

The invention provides a new track initiation determination method, a related device and a computer storage medium, and the method comprises the steps: carrying out the region division of a surrounding environment, and obtaining a plurality of environment regions; for each environment area, according to the measured values of all the moving targets in the environment area, determining the dominant course of the environment area; and when the new track exists in the environment area, determining the potential course and the target speed of the new track by using the dominant course of the environment area and the azimuth angle and the Doppler speed of the new track. The influence of a complex environment on the traffic flow identification precision is reduced, and the accuracy and efficiency of track initiation are effectively improved.

The invention provides an underwater robot positioning method and system. The method comprises the following steps: acquiring a camera image and an event data stream acquired by an underwater robot; performing event motion compensation on event frames in the event data stream to obtain event frames after motion compensation; acquiring a plurality of first candidate features and a plurality of second candidate features, performing multi-frame tracking on the plurality of first candidate features and the plurality of second candidate features, and determining a first permanent landmark and a second permanent landmark; and constructing a joint optimization function of the underwater robot according to the standard frame reprojection error, the event frame reprojection error, the inertial measurement unit error and the Doppler velocity instrument velocity error, and obtaining positioning state information of the underwater robot according to a solving result of the joint optimization function. According to the invention, accurate and robust autonomous positioning of the underwater robot in a weak-light underwater environment is realized.

The invention discloses a Doppler velocity filtering multipath false target suppression method and device, and a medium, and belongs to the technical field of millimeter wave radar target detection. The method comprises the following steps: acquiring radar point cloud data; performing dynamic and static point cloud data separation on the radar original echo data to obtain a static point cloud set and a dynamic point cloud set; clustering the static point cloud set, and performing linear boundary fitting according to a clustering result to obtain a linear equation of a reflection boundary; doppler velocities of corresponding first-order and second-order multipath false targets are respectively estimated for trace points in the dynamic point cloud set, and corresponding Doppler velocity search intervals are obtained; traversing the dynamic point cloud set, and performing global point cloud Doppler velocity filtering on the obtained search interval to obtain a filtered dynamic point cloud set; and performing multi-dimensional information judgment on the filtered dynamic point cloud set, and identifying a multi-path false target so as to realize multi-path false target suppression. According to the method, Doppler information is effectively utilized, so that a multipath false target is effectively identified and suppressed.

The invention provides a synchronous positioning and mapping method for underwater pipeline detection, and belongs to the technical field of underwater robot navigation and positioning. In order to solve the problems of limited illumination, strong echo interference, high structural repeatability and the like in a seawater pipeline environment, the invention provides a factor graph optimization-based tight coupling pose estimation framework fusing a two-dimensional imaging sonar, a Doppler velocity meter DVL and an inertial measurement unit IMU. Through joint constraint and optimization of multi-source sensing information, the method can realize high-precision positioning and continuous mapping of the ROV in an environment with extremely low visibility and a complex pipeline structure, and effectively improves autonomy and data reliability of an underwater inspection process. The method is clear in structure, easy and convenient to implement, high in calculation efficiency, capable of stably running on a conventional ROS platform and suitable for various types of underwater pipeline detection and inspection tasks.

The invention provides a broadband beam forming acoustic Doppler velocity measurement system and method based on time delay control, which can transmit and receive broadband signals and solve the problem that the measurement precision of the existing acoustic Doppler velocity measurement system is influenced by bandwidth. The velocity measurement system comprises a transducer module, a beam forming module and a conversion module, the transducer module comprises a planar transducer array and an impedance matching module connected with the planar transducer array; the transducer module is in signal connection with the beam forming module through the conversion module, and the beam forming module is used for performing time delay compensation and weighting processing on a received signal; and the conversion module is used for converting the echo signal acquired by the transducer module into a digital signal and inputting the digital signal into the beam forming module, or converting a to-be-transmitted signal received from the beam forming module into an analog signal and transmitting the analog signal through the transducer module.

The invention belongs to the technical field of ultrasonic Doppler blood flow imaging, and particularly relates to a three-dimensional ultrasonic vector Doppler imaging method based on a row-column addressing array. According to the method, three-dimensional ultrasonic vector Doppler imaging is realized by combining a high-frame-rate two-dimensional non-focused wave emission sequence and a row-column addressing array (RCA) of a least square multi-angle Doppler velocity estimator; the method specifically comprises the following steps: acquiring radio frequency data from each oblique non-focused wave emission, and then performing IQ demodulation, beam forming and clutter filtering; performing high-frame-rate multi-angle vector Doppler analysis and speed estimation on a result through RCA; and dual-wavelength anti-aliasing processing is carried out. According to the invention, the imaging speed of more than thousands of frames can be realized, the sensitivity to low-speed flow and the measurement accuracy to high-speed flow are obviously improved, and clinical environment experimental verification is carried out; the method is suitable for clinical application, especially for blood flow dynamic monitoring of large blood vessels, and important support can be provided for blood flow dynamic research and clinical diagnosis.

The invention provides a method and device for detecting a melting layer in cloud, electronic equipment and a storage medium, and belongs to the technical field of remote sensing image processing, and the method comprises the steps: obtaining a melting layer probability value, judged in each distance library, between each radar observation profile of a to-be-observed region and a profile template; and calculating the melting layer probability values corresponding to all the distance libraries in each radar observation profile, determining whether the melting layer in the cloud exists in the to-be-observed area, and outputting the height of the melting layer in the cloud. According to the method and the device for detecting the melting layer in the cloud, the electronic equipment and the storage medium provided by the invention, the non-dimensionalized radar observation profile including the reflectivity factor template and the Doppler velocity template is used for matching the observed radar observation profile, so that the probability that the melting layer appears in each distance library is calculated; and empirical parameters are not needed, and a temperature profile or a 0 DEG C layer height is not needed, so that the independence of radar identification of a melting layer and the reliability of actual operation are enhanced. The calculation mode is simple and the result is visual.

The invention provides a Doppler speedometer residual error construction method for underwater robot positioning. The method belongs to the field of underwater robot positioning. Comprising the following steps: firstly, measuring the three-dimensional speed of the underwater robot through a DVL (Doppler velocity meter); secondly, a reference coordinate system of DVL measurement data is converted into an IMU coordinate system through external parameters between the DVL and an IMU; measuring noise parameters and external parameters between the DVL and the IMU through a DVL sensor and an IMU sensor, and calculating a DVL factor covariance matrix; then calculating a DVL residual error through a system state estimator, an external parameter between the DVL and the IMU and measurement data of the DVL and the IMU; and finally, through the system state estimator and the external parameters between the DVL and the IMU, calculating the Jacobian matrix of the residual error of the DVL relative to the system state estimator. According to the novel DVL residual construction method suitable for nonlinear optimization provided by the invention, DVL measurement data are accurately utilized, so that the positioning precision and robustness of the underwater SLAM algorithm based on the DVL residual construction method are greatly improved compared with other underwater positioning algorithms.

The invention relates to the technical field of sensor verification and calibration, and discloses a laser Doppler velocimeter-based mileage sensor verification and calibration system, which comprises a support table, a laser Doppler velocimeter, a roller, a mileage sensor, a standard object, a data acquisition and processing system and a control system. Compared with the prior art, the device has the advantages that the detected mileage sensor is mounted on the fixed shaft with the same diameter as an actual wheel, the motor drives the fixed shaft to rotate and drives the mileage sensor to rotate along with the roller, and a laser beam emitted by the laser Doppler velocimeter irradiates a standard object; the mileage sensor records the number of turns of rotation of the standard object and outputs corresponding mileage signals, errors of the mileage sensor are calculated through analysis and processing of the data collecting and processing system, errors existing in the mileage sensor are calculated, and compensation is carried out by adjusting parameters of the mileage sensor or using polynomial fitting and other methods.

The invention provides a spatial transformation linear fusion tracking method for a Doppler radar, and the method comprises the steps: firstly constructing a state space of a to-be-tracked target based on the distance of the target relative to the radar, the Doppler speed, the angle and a target speed module; at a preset initial moment, using Doppler radar measurement and target prior information to initialize target related parameters to obtain an initial state; then, the posterior state of the state space of the target to be tracked at the current moment is converted into a Cartesian coordinate system, the state model is used for prediction and then is switched back, and a predicted value at the next moment is obtained; then, according to a linear Kalman filtering theory, filtering and updating the predicted value and the radar measurement value to obtain an optimal state estimation value at the next moment; and finally, the steps of initialization, state transition prediction and filtering update are continuously repeated until target tracking is completed, and the method effectively realizes continuous and accurate tracking of the Doppler radar on the target.

The invention belongs to the technical field of navigation, and discloses an inertial navigation method and system based on dual modes and a medium, the dual modes comprise a first navigation mode and a second navigation mode, the first navigation mode adopts a first combined navigation mode formed by combining an inertial unit with an ultra-short baseline acoustic positioning unit and a Doppler velocity measurement unit, and the second navigation mode adopts a second combined navigation mode formed by combining an ultra-short baseline acoustic positioning unit and a Doppler velocity measurement unit. The navigation mode II adopts a second combined navigation mode of combining an inertial unit and a geomagnetic measurement unit. The method comprises the following steps: acquiring the depth of the submersible at the current position; and updating the current position of the submersible in real time by adopting the navigation mode I and / or the navigation mode II according to the depth of the submersible at the current position. The method has high positioning accuracy.

The invention provides a camera control method and related equipment thereof, and the method comprises the steps: detecting an observation region through a radar, and judging whether a target person exists in the observation region or not; if yes, radar point cloud information in the observation area is acquired, and position information of the target person is determined; according to the position information, designated feature information of the target person is obtained, the motion state of the target person is recognized, and the designated feature information comprises at least one of Doppler velocity information, micro-Doppler frequency information and position information; and activating a camera according to the motion state of the target person, and outputting position information of the target person. Through fusion of the radar and the camera, the radar serves as an activation switch for working of the camera, so that the camera is started to work when needed, and the power consumption of the camera is reduced. In addition, the information of the target position can be acquired in real time through the radar, and the target person can be accurately positioned.

The invention discloses a mapping method and device based on a 4D millimeter wave radar and a computer readable medium, and the method comprises the steps: carrying out the noise reduction of a 4D millimeter wave radar point cloud based on the coordinate information and RCS information of the 4D millimeter wave radar point cloud in a preset sliding window; based on the Doppler velocity, performing dynamic point cloud filtering processing on the preprocessed point cloud to obtain static point cloud; and for any current frame point cloud in the static point clouds, performing conversion processing on the current frame point cloud based on the pose conversion matrix, and performing feature point registration on the converted current frame point cloud and a previous frame sub-map to generate a current frame sub-map. According to the embodiment of the invention, based on RCS information and Doppler velocity, filtering processing is carried out on point clouds collected by a 4D millimeter wave radar; and feature point registration is carried out on the static point cloud obtained after filtering to form a local sub-map. Therefore, the point cloud in the target scene can be subjected to high-precision registration, so that high-precision positioning of the unmanned equipment is realized.

The invention discloses an environment disturbance plume experiment device and method for deep-sea mining vehicle movement. The device mainly comprises the following three parts: a layered environment water body generation device, a mining vehicle motion simulation system and an environment disturbance plume observation system. The mining vehicle motion simulation system is composed of a mining vehicle model, an electric sliding rail with adjustable motion modes and a double-shaft controller, the double-shaft controller jointly controls the mining vehicle motion simulation sliding rail and the double sliding rails of the environment disturbance plume observation system to move synchronously, and different motion modes are set through motor programs. The mining vehicle is driven to move so as to simulate a disturbance plume development process generated by environment disturbance, and a disturbance plume diffusion process and intensity are recorded by a particle image velocity measurement system, a turbidimeter, a Doppler velocity meter and the like. According to the invention, the environmental disturbance process of the mining vehicle in an actual deep sea environment can be simulated, and a target object and post-processing method under a moving condition observed by using a particle image velocity measurement system is optimized.

The invention provides an outdoor cross-modal robust positioning and navigation method for extreme severe weather, and relates to the field of online positioning and navigation of mobile robots. The method comprises the following steps: acquiring and preprocessing data; generating a path point set based on a CMR network, perfecting the path point set through local trajectory fitting and error optimization, and constructing a path point relative pose measurement-topology hybrid map; motion prior estimation is carried out based on Doppler velocity, effective matching prior estimation is generated in combination with LiDAR odometer information, cross-modal pose estimation is carried out through a CMR network, and a pure tracking strategy and PD controller path point tracking are adopted; and geometric and intensity alignment is carried out on the forward 4D millimeter wave radar point cloud and the omnidirectional 3D laser radar point cloud through a CMR network, a rotation matrix and a translation vector are output, and accurate positioning is completed. According to the invention, the sensing and positioning defects in extreme weather in the prior art are overcome, and the positioning precision and robustness are improved.

The invention discloses a Doppler blood flow velocity estimation method based on high-frequency pulse differential frequency, and solves the problems of velocity estimation resolution reduction and artifacts caused by alternate transmission of a B mode and Doppler pulses in an ultrasonic dual-mode system. The method comprises the following steps: transmitting a high-frequency broadband ultrasonic signal compatible with B-mode imaging; the method comprises the following steps: receiving a superficial blood vessel echo signal, performing time domain sampling, converting into a discrete signal, extracting a narrow-band frequency spectrum through frequency sampling, and generating a low-frequency equivalent signal by using a multi-frequency-point differential frequency technology; calculating a covariance matrix of each signal, performing average weighting to remove artifacts, and generating low-frequency equivalent covariance data; and estimating the blood flow velocity through eigenvalue decomposition and spectral peak search. According to the method, two pulses do not need to be transmitted alternately, resolution reduction and artifacts are avoided, Doppler velocity estimation precision is remarkably improved, integrated waveform design is supported, and hardware implementation is simplified.

The invention relates to the technical field of medical instrument volume detection, and discloses a medical instrument internal volume detection system. A continuous wave and a pulse modulation signal are simultaneously transmitted through an annular phased array microwave antenna array, three-dimensional dielectric constant distribution is reconstructed by adopting a compressed sensing algorithm, and Doppler time-frequency domain characteristics are extracted through short-time Fourier transform; and inputting the phase gradient field and Doppler velocity field features into a convolutional neural network to generate a four-dimensional space-time volume evolution model, separating a macroscopic volume trend and a microcosmic pulsation component by adopting an adaptive Kalman filtering algorithm, and predicting an abnormal hemodynamic event through a long-short-term memory network. The technical problem of real-time precise detection of the multi-dimensional volume parameters of the blood circulation medical instrument under the complex pulsating flow condition is solved, and accurate evaluation of the instantaneous volume value, the pulsation amount and the pulsating frequency spectrum and early warning of abnormal events are achieved.

The present invention discloses a space-time inversion method for ocean wave parameters using a shipborne coherent S-band radar, comprising the following steps: obtaining a space-time Doppler spectrum and extracting the average Doppler frequency deviation; estimating a space-time radial velocity sequence and converting it into a wavenumber frequency spectrum; estimating the wavefield energy and group line energy distribution and designing an adaptive filter; filtering the wavenumber frequency spectrum and reconstructing a space-time radial Doppler velocity sequence; estimating the wavenumber directional spectrum; repeating the above process to obtain six wavenumber frequency spectra and inverting an undirected ocean wave spectrum; and finally inverting the ocean wave parameters. This method addresses the impact of breaking waves and ship motion on the accuracy of ocean wave parameter inversion. It not only retains the advantages of shore-based coherent microwave radar but also overcomes its shortcomings in spatial scalability and temporal continuity, significantly improving the robustness and accuracy of ocean wave parameter inversion using shipborne coherent S-band radar.

The invention belongs to the technical field of electrical equipment measurement, and particularly relates to a transformer fault positioning method based on a photoelectric conversion integrated device of a laser Doppler velocity measurement system. Building a transformer oil flow velocity analog simulation model based on a laser Doppler velocity measurement system photoelectric conversion integrated device; transformer flow velocity field distribution characteristics in different fault modes are analyzed, and an installation and arrangement strategy of flow velocity sensors in the transformer box wall is determined; fault codes are constructed according to sensor measurement data, and transformer fault positioning is realized based on the fault codes. The photoelectric conversion integrated device of the laser Doppler velocity measurement system comprises a laser, a first optical fiber coupler, an optical fiber circulator, a second optical fiber coupler and a photoelectric detector. Integrated optimization design is carried out according to an existing Doppler optical flow velocity sensor structure, the fault type can be quickly determined, the fault occurrence position can be positioned, and the reliability and accuracy of field application are improved.

A computer-implemented method for estimating a travelling speed of a wireless device in a wireless communications network, where the wireless device has transmitted a signal sequence to a network node via two or more signal paths. The method includes obtaining data indicative of a Doppler speed difference between respective multipath components of the signal sequence transmitted via the two or more signal paths; obtaining data indicative of direction of departure, DoD, (nUE,P1, nUE,P2) of the two or more signal paths at the wireless device; and estimating the travelling speed of the wireless device based on the data indicative of the Doppler speed difference and the data indicative of DoD.

The invention discloses a device and method for simultaneously determining the detonation velocity and detonation pressure of micro-scale charge, and belongs to the technical field of detonation performance testing of energetic materials. The device comprises a laser, a charging system, a detonation velocity testing system and a detonation pressure testing system, the charging system comprises a charging clamp, a sample containing groove and a sample ring, the sample containing groove is fixed in the charging clamp, and the sample ring is assembled in the sample containing groove; the detonation velocity testing system comprises a probe, a direct-current power supply and an oscilloscope; the detonation pressure testing system comprises an optical fiber and a photon Doppler velocity tester. During use, a to-be-tested sample is pressed into the sample rings, the probe is embedded between the two sample rings, the to-be-tested sample is detonated by using energy provided by the laser, the detonation velocity and detonation pressure of the to-be-tested sample can be measured at the same time, the sample amount required by a single shot experiment is within 200 mg, and compared with a traditional test method, the sample consumption is greatly reduced, and meanwhile, the test safety is improved.

The invention discloses an under-water flow tumble detection system based on multi-scale fusion and decision, which comprises the following steps of: acquiring radar signals in a detection area by utilizing a millimeter wave radar, constructing a distance Doppler spectrum, calculating a water flow dynamic clutter index based on energy distribution statistical characteristics, identifying a background noise type and dynamically generating a detection threshold; target point cloud extraction under a complex dynamic water flow background is realized; the method comprises the following steps: performing track initialization and state updating by constructing a two-stage gating and evidence judgment framework, executing online parameter self-adaption and target physical size estimation, extracting time sequence characteristics such as a centroid position and Doppler velocity, and constructing a characteristic vector; and establishing a finite state machine model based on the feature vectors, identifying state transition, fall confirmation and state rollback conditions, and outputting a fall judgment result or a rollback result. According to the invention, accurate identification and dynamic determination of a fall event in a wet, slippery and water flow complex environment are realized.

The invention discloses a Doppler velocity measurement method based on a phase difference. The method comprises the following steps: step 1, carrying out distance dimension matched filtering on a two-dimensional echo data matrix acquired by a radar to obtain a data matrix after matched filtering; step 2, taking out phase data of velocity dimension data corresponding to a peak value in the matched and filtered data matrix; step 3, subtracting two adjacent phase data in all the phase data one by one to obtain a group of phase differences; 4, preprocessing the phase difference, namely, when the phase difference exceeds a set range, considering that the phase difference is unqualified, and removing the phase difference; 5, averaging all the phase differences after rejecting the unqualified phase differences to obtain an estimated phase difference; and 6, according to the estimated phase difference and the pulse repetition period, calculating to obtain the target speed. According to the method, the radar speed measurement precision is effectively improved, and meanwhile, compared with an existing method, the calculated amount is reduced.