233 results about "Approximation error" patented technology

An RMS-to-DC converter implements the difference-of-squares function by utilizing two identical squaring cells operating in opposition to generate two signals. An error amplifier nulls the difference between the signals. When used in a measurement mode, one of the squaring cells receives the signal to be measured, and the output of the error amplifier, which provides a measure of the RMS value of the input signal, is connected to the input of the second squaring cell, thereby closing the feedback loop around the second squaring cell. When used in a control mode, a set-point signal is applied to the second squaring cell, and the output of the error amplifier is used to control a variable-gain device such as a power amplifier which provides the input to the first squaring cell, thereby closing the feedback loop around the first squaring cell. Accurate square law approximation at microwave frequencies can be achieved by implementing the squaring cells as series-connected three-transistor multi-tanh transconductance cells. By using carefully balanced squaring cells and a well-balanced error amplifier, approximation errors are cancelled and accurate RMS measurement is realized at high frequencies. A feedforward bootstrapping feature uses an op amp to balance the voltages at the common nodes of the transconductance squaring cells and also provides a balanced differential input drive to one of the squaring cells. A base current compensation circuit for providing accurate base compensation current to both of the squaring cells prevents errors due to DC offset voltages.

A road shape recognition device includes: distance and height detecting means for detecting distance data having a distance and height in real space regarding a road surface where a vehicle is traveling at multiple mutually different points; approximation line calculating means for dividing the plurality of distance data into near and far groups as viewed from the vehicle to calculate an approximation line of the distance data for each group each time the distance data of the boundary portion between the two groups is transferred from one of the groups to the other; statistics calculating means for calculating statistics from the corresponding approximation line for each group where the distance data is transferred; and road shape model generating means for selecting one out of combinations of the approximation lines to generate a road shape model using the selected combination.

The invention, which belongs to the robot system control field, relates to a distributed adaptive-neural-network continuous tracking control method of a multi-robot system. According to the existing coordinated tracking and controlling method of the multi-robot system, problems of parameter uncertainty and external interference existence in the multi-robot system exist. The provided method comprises: under the circumstances that only parts of followers can obtain dynamic navigator state information, a distributed observer design is implemented with limitation of communication tine delay existence, so that all followers can obtain the dynamic navigator state information; and with consideration of the parameter uncertainty and external interference existence in the system, controlling is carried out by using a distributed adaptive tracking control expression designed based on two neural networks, so that the approximate error is close to zero. In addition, the control algorithm of the distributed adaptive tracking control expression is in a continuous control mode, no buffet is caused at the system and the great practical application value is created. Besides, validity of the control algorithm is verified by the simulation experiment.

The invention discloses a micro-gyroscope tracking control method based on an adaptive fuzzy sliding mode. The method comprises the following steps of: designing a control law according to the linear feedback technology and a micro-gyroscope dynamic equation; adding the sliding mode control to the control law based on the method to obtain a sliding mode control law; approaching to a practical system with a fuzzy system to obtain a fuzzy sliding mode control law; and determining an adaptive law of parameters based on the method. As the fuzzy approaching error is greater than or equal to the least approaching error, a parameter in the control law is selected as the absolute value of the approaching error plus a constant greater than 0, thus the unconditional stability of the system is ensured, the system response is accelerated and the system buffeting is reduced. Through the invention, the problems that the control accuracy of a traditional micro-gyroscope control system is relatively low due to the influence of environment change as the parameter variation is not considered and the like are solved, the micro-gyroscope can be effectively and reliably controlled in the case of uncertain parameters caused by the manufacturing error or unknown and existing environmental interference, and the overall stability of the system is ensured.

A method for finding fast approximations to an optimal operational state of a physical system, using an iterative procedure for converging to a solution of a Linear Program and yielding, in addition to a lower bound for an optimal cost and an approximation to the dual variables, a value representing an optimal allocation of system resources.

A method of representing n-dimensional parametric surfaces (animated shapes) is provided that expresses all shapes in a consistent manner to reduce storage requirements, support deformation and simplify interaction between shapes. The method, a version of sweeps, represents shapes using a unique combination of three discrete types of (piecewise polynomial) curves: spine (sweeping) curves, slice (section) curves, and lathe (plane) curves, which are combined to create surfaces. The curves required to make simple 3D primitives (i.e. torus, sphere, cube and pyramid) are themselves simple 2D primitives (i.e. line, circle, square, triangle). The storage size of this system's shapes is exponentially smaller than the size of polygonal versions of the same shapes (as a function of the number of polygons). Complex models can be broken into multiple shapes, which are arranged in a tree hierarchy. The shapes of this invention can be tiled with other shapes of this invention (i.e. a row of smokestacks made of bricks). The shapes of this invention can smoothly travel on other shapes of this invention (i.e. a football rolling over arbitrary terrain). This invention supports fast, intuitive creation of shapes such as hand-drawn shapes. This invention is a closed system, providing a suite of operations that can occur in arbitrary order sans approximation errors. When scenes are constructed of parametric building blocks, each represented with the same universal formula, a suite of advanced operations becomes available, providing support critical to advanced software simulations.

The anomaly diagnosis system includes the state measure calculator acquiring sensor data from sensors in a machine facility as time series data; an approximation formula calculator calculating a state measure being an index indicating a state of the machine facility, such as anomaly and a performance by a statistical method in which the time series data is used as learned data; and a state measure estimating unit estimating the state measures until future time using the approximation formula. Whenever the latest time series data is acquired, the reference period in which the time series data corresponding to the state measure referred to calculate the approximation formula by the reference period setting unit, is successively extended by addition of time when the latest time series data is acquired. The approximation formula calculator calculates the approximation formula using the state measure of the time series data acquired in the reference period.

The invention provides a big data fault detection and positioning method for a power distribution network, and belongs to the field of intelligent power grids. The method comprises the steps: receiving voltage sampling data of the power distribution network through employing PMUs (Phasor Measurement Units); carrying out the preprocessing of voltages received by all PMUs, and constructing a receiving matrix; obtaining an unbiased estimated value of a receiving data covariance matrix through employing a random matrix theory; carrying out the eigenvalue decomposition of the covariance matrix, and obtaining a corresponding principal component; calculating a linear regression coefficient through employing PCA (Principal Component Analysis); comparing a relative approximation error and a threshold value, and achieving the fault detection and positioning of the power distribution network. The method provided by the invention solves a problem that the conventional covariance matrix estimation is biased under the measurement of a plurality of PMUs, and can achieve the real-time fault detection and positioning of the power distribution network.

The method for encoding/decoding three-dimensional meshes of dots or vertices connected in the form of facets delimited by edges; the mesh M is defined by connectivity data T and geometry data G includes the steps of:

• • lossless encoding of the connectivity data T into encoded connectivity data Tc,
  • iteratively generating a progressive mesh hierarchy, i.e. a set of meshes with progressive levels of detail, PM (M*),
  • generating a piecewise smooth approximation M* of the original mesh M, from the mesh connectivity T; this smooth approximation M* being described as follows:
  • a. compressed connectivity data Tc;
  • b. a small number N of control dots and
  • c. a number of indexes S of edges called protruding edges of the mesh M, identified beforehand,
  • using the progressive mesh hierarchy PM(M*) to calculate a prediction of approximation errors in M* compared with the original mesh M.

Improved vehicle guidance systems and methods are provided. A generated guidance curve approximates a vehicle trajectory path comprising a set of two-dimensional reference points. The guidance curve is based on a summed and weighted radial basis functions. Weighting is associated with coefficients calculated using linear least-squares regression to minimize approximation error between the guidance curve and the vehicle trajectory path. Guidance instructions are based, at least in part, on a nearest location point, and a tangent direction and curvature of the guidance curve at the nearest location point. The controller autonomously guides the vehicle along the guidance curve. The basis functions can have a cardinality less than a cardinality of the reference points. A distorting effect at the path ends can be minimized by augmenting the path ends of the vehicle trajectory path. Irregular reference point spacing can be mitigated using regularization techniques.

For converting first and second blocks of discrete values into a transformed representation, the first block is transformed according to a first transformation rule and then rounded. Then, the rounded transformed values are summed with the second block of original discrete values, to then process the summation result according to a second transformation rule. The output values of the transformation via the second transformation rule are again rounded and then subtracted from the original discrete values of the first block of discrete values to obtain a block of integer output values of the transformed representation. By this multi-dimensional lifting scheme, a lossless integer transformation is obtained, which can be reversed by applying the same transformation rule, but with different signs in summation and subtraction, respectively, so that an inverse integer transformation can also be obtained. Compared to a separation of a transformation in rotations, on the one hand, a significantly reduced computing complexity is achieved and, on the other hand, an accumulation of approximation errors is prevented.

A fast, texture morphing algorithm for real-time computer simulation and video games dynamically generates objects “on the fly” by simplifying and reducing the computational load required for a texture morphing/blending process. Incremental interpolation techniques compute a morph parameter based on previous value and morph change rate. Precomputed initial and incremental morph parameter values for each texel component are applied during real-time morphing procedures using integer arithmetic. Approximation errors are reduced by incrementing/decrementing by an extra integer value when the number of morph iterations is a multiple of a frame counter. The frame counter avoids over-runs, and the morphing procedure is “snapped” the texel value to the precise texture target value to prevent under-runs and corresponding artifacts. Interlacing (applying interpolation to a subset of the texels each frame) significantly reduces computational load without introducing significant image artifacts. The morph texture buffer data structure is initially decomposed off-line to reduce the number of real-time calculations required to manipulate texel component data.

The invention provides a self-adaptive neural network automatic berthing control method for an underactuated ship. According to the method, an additional control method is adopted for solving the difficulty of design of an underactuated controller; uncertain ship model dynamic parameters and unknown disturbance vectors are reconstructed by utilizing a neutral network self-adaptive method of navigation dynamic depth information, the neutral network weight, approximate error and disturbance quantity are taken as complex uncertain parameters to be estimated on line, the problem that since disturbance and approximate error are separated to be processed, the unknown disturbance input cannot directly approach and the coupling property to the system is neglected is solved, the uncertain couplingproperty is considered, also the design conservatism is reduced, and also the system computation load is reduced; the input saturation of rudder and paddle executors are considered in the controller,and dynamic technology and minimum study parameter methods are introduced, so that the provided control method is more convenient, and the engineer is easy to realize.

Polynomial approximation based image filter methods, systems, and machine-readable media are described. In one aspect, multiple n-order polynomial approximations to a value of a target pixel of an input image are computed from multiple respective sets of m values of pixels in a neighborhood of the target pixel, wherein n≧0 and m≧n+1. A respective approximation error is computed from each of the computed n-order polynomial approximations. A value of a pixel of an output image is computed from the target pixel value and the computed approximation errors.

The invention, which belongs to the technical field of video processing, relates to a block-blur-kernel-set-based heterogeneous video blind deblurring method. The method comprises the following steps: detecting a blurred frame according to a gradient size of a video frame image; calculating block homograph according to feature matching of a clear frame and a blurred frame; carrying out discrete sampling of the block homograph to realize blurring approximation motion and calculating a velocity parameter of the blurring motion based on approximation error optimization; according to the blurring motion velocity, obtaining burring kernels corresponding to all blocks and calculating clear blocks by using deconvolution; and splicing the clear blocks to obtain a clear frame image, thereby removing blurred frames. Compared with the prior method, the provided method is characterized in that a blurring motion of a video frame is described by using a plurality of blur kernels; no initial value needs to be set during calculation, thereby enhancing the robustness; heterogeneous video blurring processing becomes efficient; requirements on the clear area of the video are low; and the application range is widened.

Minimum cost networks, such as cellular networks, able to supply k-fold coverage to users, are obtained by defining potential network elements having cost and coverage parameters, and selecting from these available network elements using an iterative approximation method or system that first constructs a k-set coverage formulation incorporating the cost and coverage parameters of the available network elements, and then finds an optimal solution to the k-set coverage formulation using applications of GRASP (greedy randomized adaptive search procedure) and path-relinking heuristics. In one version, GRASP and path-relinking start from a random choice of a network element and build feasible solutions using greedy construction, local search and path-relinking heuristics that are iteratively applied to find an approximate solution. In a second version, a Lagrangian relaxation formulation of the k-set coverage formulation is solved with iterative subgradient optimization methods, and a Lagrangian heuristic that finds a feasible solution at each iteration of the subgradient optimization method, to modify the subgradient optimization and find an approximate feasible solution. The Lagrangian heuristic may be a greedy construction heuristic applied at each iteration of the subgradient optimization method, or may be a GRASP with path-relinking heuristic applied at each iteration of the subgradient optimization method to find an approximate feasible solution. The approximate solutions to the k-set coverage formulation are then used to select at least some of the potential network elements for use in a minimum cost network. The method and system may be software or hardware implementations of conventional computer equipment enabling good approximate solutions to be obtained in reasonable times.

The invention discloses a machining method based on a Bezier curve corner smooth transition algorithm. The machining method comprises the following steps: firstly, acquiring discrete data points of the tracks of small line segments by using CAD/CAM software; secondly, reading in three data points, marking a middle point as an inflection point, and calculating the length, the rotation angle and theunit direction vector of micro line segments on the two sides of the inflection point; thirdly, constructing different corner arc transition vector models with G2 continuous characteristics accordingto the value range of the central angle; fourthly, calculating a transition error and a curvature extreme value, determining the positions of transfer points on the two sides of the corner and the length of a transition section according to a preset approximate error constraint and a maximum curvature limit, and substituting the positions and the length into the model to solve a transition curve,thus completing smooth transition of one corner; and fifthly, repeatedly reading in data points, sequentially finishing smooth transition of all corners, and outputting a processing path for realizing smooth connection between small line segments by adopting the transition curves.

The invention discloses a variable error non-linear adaptive control method; a proper approximation error is introduced to approach a performance index function and a strategy control function, so the index function can finally realize uniform convergence. The method combines with a nerve network; because of excellent approach performance of the nerve network, and evaluate network and strategy network approximation errors can be simultaneously adjusted, so finally the performance index function can be converged into a neighborhood of an optimal evaluate function.

The invention discloses a surface modeling method blended by interpolation type segmentation and approximation type segmentation and belongs to the field of computer aided design and manufacturing technology. Based on the internal relation between the existing interpolation type segmentation and approximation type segmentation, the method provides a method blended by an approximable Catmull-Clark segmentation mode and an interpolation mode based on tensor product four-point interpolation, thus achieving the purpose that local interpolation segmentation curve, tessellated mesh and the tessellated mesh generated between the interpolation grids and the approximation grids can be obtained without needing to reversely obtain control vertex or to solve equations sets and solving the jump problems of 'expansion' or 'contraction' when multiresolution is used for expressing.