2806 results about "Curve fitting" patented technology

An Ultra-Tightly Coupled GPS-inertial navigation system for use in a moving agile platform includes a range residual extractor that uses best curve fitting of a third order polynomial for estimating range residual. The curve-fitted residual is used to update an error Kalman filter. The error Kalman filter includes correction for navigation solution, and IMU and GPS parameters. The navigation solution together with GPS parameter corrections are used in a Tracking Predictor to generate high-sampling-rate carrier and code replicas. The curve-fitting error covariance indicates signal to noise ratio for the tracked GPS signal and may be used for early indication of interference or jamming.

A general method is described for producing an inexpensive touchscreen system that provides accurate positional information and compensates for manufacturing variations without complicated sensor arrangements. Utilizing a set of sensed signals that are unique to each location on the touchscreen sensor, equations for X and Y are derived via curve fitting methods. The coefficients of the equations are stored with the sensor. During touchscreen operation the coefficients are used to calculate X and Y to the desired accuracy directly and independently.

A method for detecting the lane departure of a vehicle includes an image recognition process and a deviation estimation process. The image recognition process includes the following steps: an image capturing step for capturing image frame data by using an image capturing unit; and a lane line recognition for analyzing the image frame data for determining the lane lines. By using a quadratic curve fitting equation, a plurality of lane line being detected so as to establish a road geometry estimation model. The road geometry estimation model is inputted into the deviation estimation process to detect the lane departure of the vehicle so as to alert the driver. Furthermore, an apparatus for detecting the deviation of the vehicle, comprising: an image capturing unit, a processing unit and a signal output unit.

Techniques, hardware, and software are provided for quantification of extensional features of structures of an imaged subject from image data representing a two-dimensional or three-dimensional image. In one embodiment, stenosis in a blood vessel may be quantified from volumetric image data of the blood vessel. A profile from a selected family of profiles is fit to selected image data. An estimate of cross sectional area of the blood vessel is generated based on the fit profile. Area values may be generated along a longitudinal axis of the vessel, and a one-dimensional profile fit to the generated area values. An objective quantification of stenosis in the vessel may be obtained from the area profile. In some cases, volumetric image data representing the imaged structure may be reformatted to facilitate the quantification, when the structural feature varies along a curvilinear axis. A mask is generated for the structural feature to be quantified based on the volumetric image data. A curve representing the curvilinear axis is determined from the mask by center-finding computations, such as moment calculations, and curve fitting. Image data are generated for oblique cuts at corresponding selected orientations with respect to the curvilinear axis, based on the curve and the volumetric image data. The oblique cuts may be used for suitable further processing, such as image display or quantification.

Methods and apparatus for actively aligning a first optical element, such as a lens, to a second optical element, such as an image sensor, use continuous scans, even absent a synchronization signal from one of the optical elements. During a scan, timed position information about the scanned optical element is collected, and then a relationship between position of the scanned optical element and time is estimated, such as by fitting a curve to a set of position-time pairs. This relationship can then be used to estimate locations of the scanned optical element at times when image data or other alignment quality-indicating data samples are acquired. From this alignment quality versus location data, an optimum alignment position can be determined, and the scanned optical element can then be positioned at the determined alignment position.

A curve fitting method is used to synchronize a reader of embedded data in a media signal. A circular reference signal is embedded in the media signal. After geometric distortion of the media signal, the reference signal is distorted, yet still detectable. The amount of distortion is derived by detecting the reference signal, and applying a curve fitting method from which the distortion is calculated.

The embodiments provide methods for use in designing and/or manufacturing optical systems. Some embodiments further provide for the optical systems generated utilizing the methods for use in designing and/or manufacturing. In some embodiments, a method simultaneously generates first and second sets of span points defining first and second surfaces, respectively, where sets of span points are interdependent. The method curve fits through the first and second sets of span points defining initial first and second spines, smoothes the curve fittings such that tangent vectors are perpendicular to normal vectors, and defines patches of the first and second surfaces relative to the first and second spines. Some embodiments simultaneously generate the first and second sets of span points by alternatively determining the points of the sets based on propagation of input wavefronts and associated output wavefronts relative to previously determined points.

A system and method for patient control of the stimulation parameters of a Spinal Cord Stimulation (SCS) system, or other neurostimulation system, provides an increased Therapeutic Ratio (TR). Measurements of the just-perceptible stimulation level and the maximum-comfortable stimulation level are made for at least two values of pulse duration and two values of pulse amplitude. A Therapeutic Ratio is determined for stimulation level control strategies based on fixed pulse duration and variable pulse amplitude, and alternatively for fixed pulse amplitude and variable pulse duration. The control strategy providing the greatest therapeutic ratio is then selected for use by the patient. In an alternative embodiment, the pulse durations at the just-perceptible and maximum-comfortable stimulation levels are measured, and the pulse amplitudes at the just-perceptible and maximum-comfortable stimulation levels are determined using a curve-fitting process. Similarly, the pulse amplitudes may first be measured and the pulse widths determined using a curve-fitting process.

An object's position and/or motion in three-dimensional space can be captured. For example, a silhouette of an object as seen from a vantage point can be used to define tangent lines to the object in various planes (“slices”). From the tangent lines, the cross section of the object is approximated using a simple closed curve (e.g., an ellipse). Alternatively, locations of points on an object's surface in a particular slice can also be determined directly, and the object's cross-section in the slice can be approximated by fitting a simple closed curve to the points. Positions and cross sections determined for different slices can be correlated to construct a 3D model of the object, including its position and shape. A succession of images can be analyzed to capture motion of the object.

A system and method for performing a curve fit on a plurality of data points. In an initial phase, a subset P_max of the plurality of points which represents an optimal curve is determined. This phase is based on a statistical model which dictates that after trying at most N_min random curves, each connecting a randomly selected two or more points from the input set, one of the curves will pass within a specified radius of the subset P_max of the input points. The subset P_max may then be used in the second phase of the method, where a refined curve fit is made by iteratively culling outliers from the subset P_max with respect to a succession of optimal curves fit to the modified subset P_max at each iteration. The refined curve fit generates a refined curve, which may be output along with a final culled subset K_final of P_max.

A computer implemented physical signal analysis method includes four basic steps and the associated presentation techniques of the results. The first step is a computer implemented Empirical Mode Decomposition that extracts a collection of Intrinsic Mode Functions (IMF) from nonlinear, nonstationary physical signals. The decomposition is based on the direct extraction of the energy associated with various intrinsic time scales in the physical signal. Expressed in the IMF's, they have well-behaved Hilbert Transforms from which instantaneous frequencies can be calculated. The second step is the Hilbert Transform which produces a Hilbert Spectrum. Thus, the invention can localize any event on the time as well as the frequency axis. The decomposition can also be viewed as an expansion of the data in terms of the IMF's. Then, these IMF's, based on and derived from the data, can serve as the basis of that expansion. The local energy and the instantaneous frequency derived from the IMF's through the Hilbert transform give a full energy-frequency-time distribution of the data which is designated as the Hilbert Spectrum. The third step filters the physical signal by combining a subset of the IMFs. In the fourth step, a curve may be fitted to the filtered signal which may not have been possible with the original, unfiltered signal.

The invention discloses a heliostat tracking error correction method. Based on the characteristics that a heliostat tracking deviation angle has small variation in a short time and the tracking deviation angles at the same moment in the adjacent days have small variation, an image collecting and processing system is adopted to detect and obtain the tracking deviation angles of a certain heliostat at multiple moments in the whole day, or the tracking deviation angles obtained by the heliostat at multiple moments in one day or previous days are taken as the intraday tracking deviation angle; an intraday tracking deviation curve of the heliostat is obtained by the interpolation; according to the tracking deviation curve, the current angle of the heliostat is corrected to ensure that the facula of the heliostat can basically accurately be projected to a target position. The invention obtains the tracking deviation angles at multiple moments by detection of heliostat tracking error many days a year or many times a day; the everyday corresponding tracking deviation curve of each heliostat can be found by one-year or multiple-year tracking deviation angle data analysis treatment and curve fitting; and thus, the facula of the heliostat can be projected to the target position more accurately.

The invention discloses a self-adaptive predistortion method, which comprises the steps: collecting emission data and feedback data, calculating loop delay according to the emission data and the feedback data, carrying out time unifying to input signals according to the loop delay, compensating collected delay of the emission data and the feedback data according to the loop delay, estimating a predistortion model parameter, constructing a matrix according to the set predistortion model parameter, calculating a predistortion parameter corresponding to a power amplifier, adopting a curve fitting method to sample and quantize the predistortion parameter to obtain an LUT table, modifying the predistortion parameter in a digital predistorter according to the LUT table, carrying out digital predistortion to the input signals according to an LUT address and the predistortion parameter which is modified, and generating the LUT address according to the amplitude of the input signals. The technical scheme of the invention saves the hardware implementation cost and can be realized in an FPGA (programmable gate array) easily.

The invention relates to a genetic-algorithm-based trajectory planning optimization method for a mobile mechanical arm. According to the technical scheme, the method comprises the following steps of first establishing a forward kinematic model and an inverse kinematic model of a multi-degree-of-freedom mobile mechanical arm; then fitting a joint trajectory by adopting a composite curve of a quartic polynomial mathematical model and a quintic polynomial mathematical model, and calculating solutions of the corresponding mathematical models according to a linear constraint equation; next selecting a trajectory optimization target according to the principles of shortest motion time, minimum spatial motion distance and less than or equal to maximum set joint torque of the mobile mechanical arm; and finally globally optimizing the optimization target by utilizing a genetic algorithm to obtain an optimal trajectory curve of an end actuator of the mechanical arm. According to the method, the trajectory planning efficiency and the tracking accuracy of the mechanical arm are improved, and the problems of real-time trajectory planning of the mobile mechanical arm and trajectory planning optimization and control of the mechanical arm in an uncertain environment are also solved; and the trajectory planning optimization method for the mobile mechanical arm is effective.

The invention relates to systems and methods for precise sub-lane vehicle positioning. A vehicle having an on-board computer, vehicle sensors, a satellite-positioning unit, a database storing a lane-level map performs a method to determine a new pose of the vehicle using map matching. The method includes the on-board computer of the vehicle receiving new data from at least one of the vehicle sensors and collecting measurements from the vehicle sensors. The method also includes the on-board computer of the vehicle computing propagation of vehicle pose with respect to consecutive time instances and performing a curve-fitting process. The method further includes the on-board computer of the vehicle performing a sub-routine of updating at least one observation model based on results of the curve-fitting process, performing a tracking sub-routine including using a probability distribution to update the vehicle pose in terms of data particles, and performing a particle filtering sub-routine based on the data particles to compute the new vehicle pose.

The invention discloses a method for fitting and interpolating a G01 code based on a quadratic B spline curve, comprising the following steps of: by an adaptive approach selecting each characteristic point of each group of small line segment which is described by the G01 code; fitting a route which is to be processed with the quadratic B spline curve of all the characteristic points; according to the characteristic of the quadratic B spline curve and the limit of the acceleration of each driving shaft of the numerical control machine, simultaneously obtaining the maximum permissible machining velocity curve (VLC curve) of the quadratic B spline curve and the each speed key point on the VLC curve; according to the each speed key point, the control axis of the each key point, the maximum permissible machining velocity and the VLC curve, computing real machining velocity; according the real machining velocity curve and a interpolating error computing interpolating point and completing real-time interpolation. The invention has fast computing velocity, high machining precision, stable working performance and wide application range, can complete the interpolating computation of the spline curve in real time and meet digital control processing requirement of fast velocity and high precision under a premise that the preset precision of the system is met.

A method of designing lithographic masks is provided where mask segments used in a model-based optical proximity correction (MBOPC) scheme are adaptively refined based on local image information, such as image intensity, gradient and curvature. The values of intensity, gradient and curvature are evaluated locally at predetermined evaluation points associated with each segment. An estimate of the image intensity between the local evaluation points is preferably obtained by curve fitting based only on values at the evaluation points. The decision to refine a segment is based on the deviation of the simulated image threshold contour from the target image threshold contour. The output mask layout will provide an image having improved fit to the target image, without a significant increase in computation cost.

The invention discloses a method and system for pasting an image to a human face based on affine transformation. Characteristic point locating and characteristic point extraction are carried out on a standard human face image, curve fitting is carried out on extracted characteristic points of the standard human face image through a Lagrange's interpolation method, standard grain coordinates are obtained, then characteristic point locating is carried out on the human face image to be processed, self-adaption matching is carried out on the standard grain coordinates and the corresponding characteristic points of the human face image to be processed through affine transformation according to the actual characteristic points of the human face image to be processed, and transformation grain coordinates are obtained; finally, image pasting materials are drawn on the corresponding characteristic points of the human face image to be processed through the transformation grain coordinates, and an effect human face image is obtained. Therefore, the method and system can adapt to human face portions in various shapes by itself, the processed effect human face image is more natural, and the problem of robustness of automatic decoration is solved.