347 results about "Doppler velocity" patented technology

An ultrasound imaging system with pixel oriented processing is provided in which a method of producing a Doppler velocity image is accomplished by emitting unfocused acoustic signals into a medium over substantially an entire field; receiving scattered and reflected ultrasonic signals on a transducer array in response to the emission; processing the received ultrasonic signals to extract information to construct a Doppler velocity signal corresponding to at least one point in the medium; and generating on a display device the Doppler velocity image from the processed Doppler velocity signal. Acquisition sequences and signal processing algorithms are described that provide improved quantification of fluid flow parameters, including improved discrimination between regions of blood flow and tissue. Very high frame rate Spectral Doppler and Vector Doppler acquisition modes for real-time and post-acquisition visualization over a large field of view are described.

A method and apparatus is provided, whereby a scanning, polarization and frequency diverse radar system measures the complete polarimetric characterization of weather targets without loss of scanning speed and without an additional ambiguity in the Doppler velocity beyond that given by Nyquist's sampling theorem. In one embodiment, a linear combination of a horizontally and a vertically polarized signal are transmitted at a predetermined first frequency. Cotemporaneously or nearly cotemporaneously with the transmitted signal of the first frequency, a horizontally polarized signal is transmitted at a predetermined second frequency. Horizontal and vertical receive channels receive echoes at the predetermined first frequency to determine, but not limited to determine, the co-polar elements of the scattering matrix. Horizontal and vertical receive channels receive echoes at the predetermined second frequency to determine, but not limited to determine, the cross-polar elements of the polarization matrix. The predetermined first and second frequencies are selected to maximize isolation yet allow practical implementation.

The invention belongs to the technical field of multi-radar networking plot fusion, and particularly relates to a multi-radar plot fusion method. The method comprises the following steps of 1, receiving multiple pieces of radar measurement data, conducting space alignment and setting a uniform measurement coordinate system; 2, judging whether the radar measurement data all contains target Doppler velocity information or not, if yes, executing the step 3, and otherwise, executing the step 6; 3, conducting time alignment; 4, conducting plot association and plot fusion to obtain fused plot information; 5, conducting track association with a formed track and filtering updating by utilizing the fused plot information, and executing the step 7; 6, sorting the data by time, and conducting track association with the formed track and filtering updating in sequence by utilizing the sorted data; 7, conducting track initiation by utilizing the radar data which does not participate in track association; 8, outputting a track result. The multi-radar plot fusion method is beneficial to prolonging the target detection distance and improving the tracking precision and the maneuvering target tracking performance.

A system uses range and Doppler velocity measurements from a lidar system and images from a video system to estimate a six degree-of-freedom trajectory of a target. The system calibrates the lidar subsystem with the video subsystem in two stages. In a first stage, the system calibrates the lidar subsystem so that lidar measurements provide 3D lidar coordinates. In a second stage, the system relates the 3D lidar coordinates with a video image obtained from the video subsystem.

The invention provides a laser dynamic deflection survey vehicle. The survey vehicle comprises a mobile measuring table, a measuring cross beam, a running wheel, a velocity measuring wheel, an accelerometer and a data acquiring and processing device. The laser dynamic deflection survey vehicle provided by the invention has the following advantages: according to the laser Doppler velocity measurement principle and the inertia measurement principle, during the driving process of the vehicle at a normal traffic velocity (15-80km/h), a plurality of laser Doppler vibration meters arranged in the front of loading wheels of the vehicle synchronously measure the relative movement velocity of various measuring points on a road surface; the instantaneous deflection deformation velocity of the road surface is obtained through inertia compensation calculation; and a dynamic deflection value of the road surface is obtained through inversion by utilizing a road layered elastic mechanical model and used for general investigation and assessment of the bearing capacity of a road network.

A system uses range and Doppler velocity measurements from a lidar system and images from a video system to estimate a six degree-of-freedom trajectory of a target. The system estimates this trajectory in two stages: a first stage in which the range and Doppler measurements from the lidar system along with various feature measurements obtained from the images from the video system are used to estimate first stage motion aspects of the target (i.e., the trajectory of the target); and a second stage in which the images from the video system and the first stage motion aspects of the target are used to estimate second stage motion aspects of the target. Once the second stage motion aspects of the target are estimated, a three-dimensional image of the target may be generated.

A system uses range and Doppler velocity measurements from a lidar subsystem and images from a video subsystem to estimate a six degree-of-freedom trajectory of a target. The video subsystem and the lidar subsystem may be aligned with one another by mapping the measurements of various facial features obtained by each of the subsystems to one another.

A system uses range and Doppler velocity measurements from a lidar system and images from a video system to estimate a six degree-of-freedom trajectory (6DOF) of a target. The 6DOF transformation parameters are used to transform multiple images to the frame time of a selected image, thus obtaining multiple images at the same frame time. These multiple images may be used to increase a resolution of the image at each frame time, obtaining the collection of the superresolution images.

The invention provides a signal processing method and device for frequency-agile radar based on a variable repetition frequency technology. The method includes the following steps: designing a frequency point sequence of random hopping according to a random number and the carrier frequency related parameters of radar, and designing a pulse time interval sequence according to the frequency point sequence and the distance range of a target to be detected; emitting a radar pulse signal according to the designed frequency point sequence and the designed pulse time interval sequence, receiving an echo signal of the radar pulse signal, and sampling and preprocessing the echo signal to obtain a baseband echo sampling signal; processing the baseband echo sampling signal by a single pulse to obtaina time-domain echo signal after pulse compression; and coherently accumulating the time-domain echo signal after pulse compression in the two dimensions of frequency point and pulse number, and obtaining the fine resolution distance and Doppler velocity values of the target to be detected through threshold decision. Accurate detection of the distance and velocity of a moving target by coherent frequency-agile radar is realized, and the amount of computation for the processing of coherent frequency-agile signals can be reduced.

The present invention relates to a system for using signals scattered by targets to determine position and velocity for each of the targets and comprises a set of transmitters and receivers of electromagnetic or acoustic signals, said transmitters and receivers dispersed to known points. Each pair of transmitter and receiver, monostatic or bistatic, is named a measuring facility. The ranges of the transmitters are chosen so that a target at an arbitrary point within the position space can be measured via scattering in the target by at least four measuring facilities. For each measuring facility, target detection occurs with constant false alarm rate in the form of probabilities over resolution cells with regards to range and Doppler velocity and conceivable targets are placed in a 2-dimensional linear space belonging to the measuring facility. The 3-dimensional positions and 3-dimensional Doppler velocities are represented as a 6-dimensional linear position and velocity space subdivided into resolution cells with the same resolution of range and Doppler velocity that is found at the measuring facilities. For each intersection representing detections at at least four measuring facilities the probability is calculated that the intersection is a false alarm emanating intersections between subsets from different targets and when the probability falls below a predefined value, it is given that the intersection contains at least one target. The target positions and target velocities are extracted in this way.”

The invention discloses a dual-polarization Doppler weather radar ground clutter inhibition method based on fuzzy logic, and the method comprises the steps: processing volume scanning data of a dual-polarization Doppler weather radar into 360 radial lines, wherein the interval between each two adjacent radial lines is one degree, and the data of each radial line comprises seven echo characteristic physical quantities: intensity, a mean Doppler speed, a spectrum width, a difference reflectivity factor, a difference propagation phase shift, and a correlation coefficient; setting the seven physical quantities which respectively comprise the intensity, the mean Doppler speed, the spectrum width, the difference reflectivity factor, the difference propagation phase shift, and the correlation coefficient; enabling seven fuzzy results to be assigned with corresponding weight values, carrying out accumulating and obtaining a ground clutter criterion of one echo point; Determining that the intensity echo of the point is the ground clutter when the ground clutter criterion of one echo point is greater than a threshold value; inhibiting the ground clutter of the dual-polarization Doppler weather radar through the ground clutter criterion of each echo point, and compensating a hole of a current layer after clutter inhibiting through employing the echo intensity value of a corresponding point in an upper layer in the volume scanning data.

The invention provides a mutual butt joint device for double intelligent underwater robots and a butt joint method. The mutual butt joint device comprises a positioning system and a butt joint system, wherein the positioning system comprises a Doppler velocity sonar, an ultra-short base line energy converter, an ultra-short base line processor, a camera, a light vision guide processing computer and a control navigation computer; and the butt joint system comprises a sliding sleeve, a butt joint supporting rod, a butt joint vision positioning light emitter, a butt joint supporting rod positioning mechanism, a sliding barrel sliding channel, a sliding barrel sliding channel motor and a transmission gear. According to different mutual distances between the two butt joint double-intelligent underwater robots, the control navigation computer can be used for positioning according to different sensor information. When the butt-joint robots are about 10 meters away from a target position, a control system sends out an instruction to slide out of the sliding sleeve; and the butt joint supporting rod is unfolded to be navigated to the target position, and is positioned and suspended by power to wait for accurate butt joint of the butt-joint robots. The intelligent underwater robot mutual butt joint device can be far away from a manual operation platform.

The invention provides a redundant controlled micro underwater robot and a fault diagnosis and fault-tolerant control method. A shell has a streamline shape spliced by a lower shell, an upper front shell and an upper back shell; an inclination compass cabin, a depth gauge, a battery tank, a Doppler speed meter, an electronic cabin, horizontal propeller impellers and a turning rise-sink control actuator are arranged inside the shell from the front to the back; and the depth gauge, the battery tank and the Doppler speed meter are arranged in parallel and positioned at the back of the inclination compass cabin together, the turning rise-sink control actuator is positioned in the middle of two horizontal propeller impellers, and the two horizontal propeller impellers and the turning rise-sink control actuator are arranged transversely in parallel and positioned at the tail of the underwater robot together. The robot and the method have the characteristics of high intellectualization degree, strong fault-tolerant capability, good safety, flexile motion, and convenient structural adjustment.

An S-surface control method for the movement of the pelagic underwater robot includes such steps as using short base line and depth meter to obtain position information, using compass to obtain attitude angle, using Doppler speedmeter to obtain speed, calculating by controller, executing movement via propeller, wings and helm, using 6-freedom position offset and variation rate as input for position control and location, using 6-freedom speed offset and variation rate as input for controlling speed, and using the indexing of PD control for non-linear control.

An ultrasonic diagnostic apparatus includes a Doppler velocity information acquiring unit, a region-of-interest-setting unit and an instantaneous flow calculating unit. The Doppler velocity information acquiring unit is configured to acquire three-dimensional Doppler velocity information from an object by a three-dimensional scan with transmission and reception of an ultrasonic wave. The region-of-interest-setting unit is configured to set a region of interest spatially. The instantaneous flow calculating unit is configured to calculate an instantaneous blood flow in the region of interest with using the three-dimensional Doppler velocity information.

The invention provides a travelable area acquisition method, a computer readable storage medium and a terminal device. The method comprises the following steps: collecting point cloud data frame by frame through a millimeter wave radar installed on a vehicle; obtaining CFAR points that are relatively stationary with respect to the ground from the point cloud data according to a traveling speed ofthe vehicle and the Doppler speed of each CFAR point in the point cloud data detected by the millimeter wave radar; obtaining an operation state of the vehicle according to the traveling speed of thevehicle and the heading angle information of the vehicle, and translating a grid probability map; projecting all CFAR points that are relatively stationary with respect to the ground in each frame into the grid probability map, and calculating a probability value of each CFAR point in the grid probability map; and taking the CFAR point with the probability value higher than a first preset value asthe point of an obstacle, and taking other areas other than the point of the obstacle as a travelable area. By processing the point cloud data, the obstacle information that is relatively stationarywith respect to the ground is accurately obtained, and the obstacle is displayed on a display screen to obtain the travelable area.

A system and method for processing data related to weather phenomena in a meteorological radar system. The method includes receiving an echo signal generated by transmitting a long pulse and employing a mismatched windowed filter on the echo signal such that the echo signal is compressed in time to achieve fine range resolution without substantially degrading sensitivity and while achieving low range time side lobes for Doppler velocities expected to be measured by the meteorological radar system.

The present invention obtains certainty of the blood-flow velocity information that is estimated in the blood-flow mapping display. The signal processor in the ultrasound imager is provided with a Doppler velocity operation part configured to calculate a Doppler velocity from echo signals by using the Doppler effect, and a first blood-flow velocity operation part configured to generate a tissue tomographic image from the echo signals and calculate a blood-flow velocity of a predetermined portion from a motion of the tissue, on the basis of the tissue tomographic image. It is further provided with a second blood-flow velocity operation part configured to calculate the blood-flow velocity of the predetermined portion by using the Doppler velocity calculated by the Doppler velocity operation part. Then, a coincidence degree is calculated between the blood-flow velocity calculated by the first velocity operation part and the blood-flow velocity calculated by the second velocity operation part, as to the predetermined portion, and according to the coincidence degree, certainty/reliability of the blood-flow velocity information is obtained and displayed.

A method and system for determining a velocity of a moving object such as a body or a stream. The object is irradiated in a non-collinear configuration with multiple ultrasound waves overlapping in a region-of-interest (ROI) of the object. An response wave, resulting from the non-linear interaction among the incident waves and the object, is detected and the frequency variations of the response wave are determined. Data representing a Doppler-shift of this frequency is further determined and processed to calculate the velocity of the moving object.

A localized dynamic light scattering measurement system includes a beam displacer for splitting an incident beam having two orthogonal linearly polarized beam components with slightly different frequencies into two orthogonal linearly polarized output beams focused onto an object to be measured. The beam displacer cooperates with an iris to collect and recombine scattering beams each reversely backscattered at 180 degrees from the object so as to form a signal beam, which is polarized by a polarizer to produce two polarization components, thereby generating a heterodyne interference signal associated with the polarization components. A signal processing unit obtains measurement data on the object based on power spectrum or autocorrelation data corresponding to the heterodyne interference signal.

The invention provides a method for estimating visual gestureattitudes of a moving target for an underwater vehicle. The method comprises the following steps of according to a mathematics model of theunderwater vehicle, enabling sensors (such as a Doppler velocimeter and a bearing and gestureattitude measuring system) to measure the linear speed, angular speed and angle of the underwater vehicleunder a carrier system, so as to obtain state information; obtaining a plurality of known feature points on the moving target, and transforming coordinate systems on the basis of a kinematics model ofthe underwater vehicle, so as to obtain the positions of the feature points of the global system under the image system, thereby obtaining the measuring information; estimating the relative positiondifference distance and moving gestureattitude of the underwater vehicle and the center of the target object by an unscented Kalman filter algorithm. Compared with the geometric method, the method hasthe advantages that the limitation of the layout of feature points requiring to meet the special conditions in the geometric method is overcome; the relative position difference distance and moving gestureattitude of the underwater vehicle and the center of the target object can be accurately estimated.