3499results about How to "Improve calibration accuracy" patented technology

A field transducer (30) for determining position or orientation in a medical instrument locating system is placed at an arbitrary position or orientation with respect to a feature (62) of the instrument (46). The transducer (30) may be attached at a arbitrary location on the instrument (46), or the instrument (400, 404) may be bent as desired by the user. A transform relating position or orientation of feature of the instrument to position or orientation of the tranducer is obtained in a caliration cycle. A field transducer may be part of a disposable unit which is irrevocably altered when used with an instrument so that the unit cannot be reused.

A communication device for transmitting and / or receiving signals by using a communication antenna includes signal characteristic information detection means for detecting information regarding signal characteristics of a calibration signal which are contained in a signal received by the communication antenna, calibration means for calibrating a communication antenna chain based on the detected signal characteristic information, and cancellation signal generating means for generating a cancellation signal corresponding to a calibration signal contained in the signal received by the communication antenna based on the calibration signal. The device also includes signal cancellation-by-subtraction means for subtracting the generated cancellation signal from the signal received by the communication antenna, and receive signal processing means for processing the received signal that is diminished by the cancellation signal.

The invention discloses a method for the automatic extraction of the position of a license plate in a vehicle monitoring image and perspective correction, and the method comprises the steps: finding an approximate range of the license plate in the image through employing the edge and color information; carrying out the linear detection of the image; determining four boundary lines forming a perspective deformation license plate through employing the regional boundary information and combining with significant straight lines; solving four intersection points of the significant straight lines, and building mapping relation between the four intersection points with four corners of a target rectangle; carrying out the reverse calculation of a perspective correction matrix, and completing the perspective correction of a license plate. The method obtains the positions of four corners of a license plate with perspective distortion, builds the mapping relation between the four corners of the license plate with perspective distortion and the four corners of the target rectangle, calculates a perspective transformation matrix, and completes the perspective correction of the license plate. Compared with an affine transformation method based on horizontal and vertical rotation, the method truly describes the perspective transformation, and guarantees the higher license plate image correction precision. Compared with an affine transformation algorithm, the method can detect the perspective distortion information of the license plate, also can precisely locate the boundary corners of the license plate, calculates the perspective transformation matrix, and accurately achieves the perspective correction of the license plate.

The invention discloses a method for calibrating a spatial coordinate measuring system of an electronic theodolite, which aims to meet the need that the measuring system of the electronic theodolite calibrates in the range of tens of meters in any direction at an angle of horizontal 360 DEG and pitching + / -45 DEG. The method comprises the following steps of: placing instruments and targets; 2, using a laser radar scanner to assign a value to the targets to form a standard instrument group; step 3, the calibrated system of the electronic theodolite measures each target to obtain measured values; step 4, converting the measured values of the electronic theodolite to a measurement coordinate system of the laser radar scanner; and step 5, comparing the converted measured values of the electronic theodolite with a standard value thereof, and obtaining the measurement deviation and measurement uncertainty evaluation of the measuring system of the electronic theodolite through software analysis. The method meets the need that the measuring system of the electronic theodolite calibrates in the range of tens of meters in any direction at the angle of horizontal 360 DEG and pitching + / -45 DEG.

The invention relates to a composite static start-stop method mass flowmeter calibration system which is used for checking the flow rate of a mass flowmeter, is a calibrating apparatus adopting the mass flowmeter that is nationally and legally prescribed and can check the main characteristics and accuracy index of the mass flowmeter. The calibration system comprises a water tank, a current stabilizer, a regulating valve, stop valves and an electronic scale, and is characterized in that a flow rate pump set is connected between the water tank and the current stabilizer, the two sides of the flowmeter to be measured are respectively connected with standard flowmeter sets, the two ends of the regulating valve are respectively provided with the stop valves, one end thereof is connected with the water tank, and the other end is connected with the current stabilizer which is connected with a weighing container; the standard flowmeter sets, the flowmeter to be measured, the regulating valve and the electronic scale are connected with a computer. The calibration system has the advantages of weighing method and standard scale method, so as to have high accuracy in calibration and working efficiency and the like; furthermore, a static start-stop method is adopted to calibrate the mass flowmeter, so that the accuracy error caused by inconsonant positive and negative strokes of a steering gear can be avoided.

A process and associated apparatus for performing defective pixel correction in a radiation detector having a plurality of radiation sensors arrayed in rows and columns. The process and associated apparatus are specifically directed to correcting defects consisting of a plurality of adjacent pixels arrayed along and connected to a common electrode forming a bad pixel line. The pixel correction is accomplished by identifying the bad pixel line, forming a window of a plurality of pixel lines co-extending along the bad pixel line; identifying a limited number of adjacent pixel lines adjacent to the bad pixel line as also being bad pixel lines; preferably subdividing the window pixels into smaller windows along the bad pixel line, deriving correction coefficients for all bad line pixels in each subdivision from the good pixels in each subdivision and using the correction coefficients to correct the pixels in both the original bad line and in the adjacent bad pixel lines.

The invention discloses a digital image correction method for a continuous variable-focal-length optical imaging system. The digital image correction method comprises the steps of acquiring planar template images which are photographed by an image camera in a plurality of discrete focal lengths, performing off-line calibration on a distortion parameter which corresponds with each focal length of a variable-focal-length lens; performing curve fitting on the distortion parameter which corresponds with each focal length for obtaining a fitting formula or establishing a distortion parameter lookup table; according to the actual operation focal length of the image camera, obtaining a lens distortion parameter which corresponds with the actual operation focal length through the distortion parameter lookup table or calculation by the fitting formula; and constructing a projection conversion relationship from an image camera coordinate system to a map coordinate system according to position gesture data and the lens distortion parameter in imaging of the image camera, and performing resampling on the pixel brightness value after coordinate conversion for obtaining an orthographic projection image after correction on the squint deformation and lens distortion. The digital image correction method realizes a purpose of simultaneous correction for squint trapezoidal distortion and variable-focal-length nonlinear distortion in the variable-focal-length imaging system.

The invention discloses a method for optimizing ultrasonic probe imaging plane space position calibration and belongs to the field of medical ultrasonic three-dimensional imaging and ultrasonic image fusion. The method is an optimizing method for calibrating the transformation relation of the space position of an ultrasonic probe imaging plane and the space position of a space position sensor, namely the space transformation matrix. Under the assisting of a three-dimensional positioning system, the method includes steps of: 1, constructing a three-dimensional positioning system; 2, manufacturing an N-line model; 3, building a coordinate system set of the positioning system; 4, calibrating a placing space position of a water tank model; 5, collecting ultrasonic images under different positions; extracting N-line marks and calculating the ultrasonic plane position; 7, mapping N-line mark points on the ultrasonic images onto a three-dimensional space plane; 8, performing registering on three-dimensional coordinate points on the imaging plane and an N line on the water tank model; 9, performing optimization calculation; and 10, calculating the optimum transformation between an imaging plane and the position sensor. The method has the advantages of reducing errors in space position calibration of the imaging plane.

The invention belongs to the technical field of measurement, and provides an optical vision measuring system with a wide-field structure and a measuring method thereof. The measuring system consists of an optical vision sensor 7 with a wide-field structure, a computer, a calibration target 8 and a calibration target 9, wherein the optical vision sensor 7 with the wide-field structure comprises a camera 1, a regular rectangular pyramid reflecting mirror 2 and four structured light projectors 3, 4, 5 and 6. The method comprises the following steps of: projecting structured light onto a wide-field scene object in a way of splicing a plurality of linear structure light projectors; forming a deformed structural light bar on the surface of a measured object; receiving the structural light bar by using the camera 1 after being reflected by the regular rectangular pyramid reflecting mirror 2; acquiring a formed image with the computer; processing the acquired image by using the computer; extracting the image coordinate of a central line of the structural light bar; and calculating the three-dimensional coordinate of a light bar point on the surface of the measured object to obtained wide-field scene information according to a measurement model. In the system, the regular rectangular pyramid reflecting mirror is used for reflecting and imaging, so that the view field range of the camera is expanded; and the system and the method are combined with a structured light vision measurement technology, so that three-dimensional sensing measurement of wide-field scene information is realized.

A disclosed hand-eye calibration method employing a two-dimension laser vision sensor and a robot comprises the following steps: step A, establishing a mathematic module of a calibration algorithm; step B, making enforcement operation step for hand-eye calibration. The step of establishing the mathematic module of the calibration algorithm realizes derivation of the mathematic module of the calibration algorithm; and the step of making the enforcement operation step for hand-eye calibration solves the concrete enforcement operation flow in the h and-eye calibration process by employing the two-dimension laser vision sensor and the robot. The method possesses the advantages of being simple, practical, agile, good in precision and the like.