1694454
Accuracy-Guaranteed Bit-Width Optimization
An automated static approach for optimizing bit widths of fixed-point feedforward designs with guaranteed accuracy, called MiniBit, is presented. Methods to minimize both the integer and fraction parts of fixed-point signals with the aim of minimizing the circuit area are described. For range analysis, the technique in this paper identifies the number of integer bits necessary to meet range requirements. For precision analysis, a semianalytical approach with analytical error models in conjunction with adaptive simulated annealing is employed to optimize the number of fraction bits. The analytical models make it possible to guarantee overflow/underflow protection and numerical accuracy for all inputs over the user-specified input intervals. Using a stream compiler for field-programmable gate arrays (FPGAs), the approach in this paper is demonstrated with polynomial approximation, RGB-to-YCbCr conversion, matrix multiplication, B-splines, and discrete cosine transform placed and routed on a Xilinx Virtex-4 FPGA. Improvements for a given design reduce the area and the latency by up to 26% and 12%, respectively, over a design using optimum uniform fraction bit widths. Studies show that MiniBit-optimized designs are within 1% of the area produced from the integer linear programming approach
53246202
Energy-optimized image communication on resource-constrained sensor platforms
2458216
Non-uniform Segmentation for Hardware Function Evaluation
This paper presents a method for evaluating functions in hardware based on polynomial approximation with non-uniform segments. The novel use of non-uniform segments enables us to approximate non-linear regions of a function particularly well. The appropriate segment address for a given function can be rapidly calculated in run time by a simple combinational circuit. Scaling factors are used to deal with large polynomial coefficients and to trade precision with range. Our function evaluator is based on first-order polynomials, and is suitable for applications requiring high performance with small area, at the expense of accuracy. The proposed method is illustrated using two functions, \(\sqrt{-\ln(x)}\) and cos(2 πx), which have been used in Gaussian noise generation.
14664253
A Bit-Width Optimization Methodology for Polynomial-Based Function Evaluation
We present an automated bit-width optimization methodology for polynomial-based hardware function evaluation. Due to the analytical nature of the approach, overflow protection and precision accurate to one unit in the last place (ulp) can be guaranteed. A range analysis technique based on computing the root of the derivative of a signal is utilized to determine the minimal number of integer bits. Fractional bit requirements are established using an analytical error expression derived from the functions that occur along the data path. Global fractional bit optimization across multiple computation stages is performed using simulated annealing and circuit area estimation functions
206418940
Residual Analysis for Feature Detection
It is shown that in a very simple form residual analysis achieves results that are at least as good as if not better than those obtained by other techniques. There are many ways for extensions of the method. For example, moving average filters of regularization can be used to obtain the residual images. Also, the strength of the correlation, measured by D/sub rr/(O), can be used to eliminate noise, weak edges, etc. A more ambitious extension is by considering smoothing filters that leave invariant the function representing the reflectance from smooth surfaces. >
2898745
The hausdorff voronoi diagram of polygonal objects: a divide and conquer approach
We study the Hausdorff Voronoi diagram of a set S of polygonal objects in the plane, a generalization of Voronoi diagrams based on the maximum distance of a point from a polygon, and show that it is equivalent to the Voronoi diagram of S under the Hausdorff distance function. We investigate the structural and combinatorial properties of the Hausdorff Voronoi diagram and give a divide and conquer algorithm for the construction of this diagram that improves upon previous results. As a byproduct we introduce the Hausdorff hull, a structure that relates to the Hausdorff Voronoi diagram in the same way as a convex hull relates to the ordinary Voronoi diagram. The Hausdorff Voronoi diagram finds direct application in the problem of computing the critical area of a VLSI Layout, a measure reflecting the sensitivity of a VLSI design to random manufacturing defects, described in a companion paper.13
206055518
Approximate evaluations of characteristic polynomials of Boolean functions
Motivated by combinational circuit verification and testing, we study the approximate evaluation of characteristic polynomials of Boolean functions. We consider an oracle model in which the values of the characteristic polynomials are approximated using the evaluations of the corresponding Boolean functions. The approximation error is defined in the worst case, average case and randomized settings. We derive lower bounds on the approximation errors in terms of the number of Boolean function evaluations. We design algorithms with an error that matches the lower bound. Let k(e,n) denote the minimal number of Boolean function evaluations needed to reduce the initial error by a factor of e where n is the number of Boolean variables. We show that k(e,n) is exponential in n in the worst and average case settings, and that it is independent of n and of order e−2 in the randomized setting.
7421438
A reliable position estimation method of the service robot by map matching
In this paper, a reliable position estimation method of the indoor service robot is proposed. The service robot PSR1 is a wheeled mobile manipulator which navigates in office buildings. Our localization method is a map-matching scheme using scanned range data, without using any artificial landmark. The proposed algorithm can provide solutions for both a global localization problem and a local position tracking. A probabilistic position estimation scheme is designed based on MCL (Monte Carlo localization). Two measure functions are developed for computing positional probabilities. The robot automatically decides whether it uses geometric pattern matching (i.e. walls, pillars) by Hough transform. The proposed scheme shows reliable performance in both polygonal environments and non-polygonal environments even there exist many obstacles. Experimental results demonstrate the validity and feasibility of the proposed localization algorithm for the service robot to navigate in an office building, using the natural environmental characteristics.
13592174
Critical area computation—a new approach
In this paper we present a new approach for computing the critical area for shorts in a circuit layout. The critical area calculation is the main computational problem in VLSI yield prediction. The method is based on the concept of Voronoi diagrams and computes the critical area for shorts (for all possible defect radii, assuming square defects) accurately in <italic>O</italic>(<italic>n</italic> log <italic>n</italic>) time, where <italic>n</italic> is the size of the input. The method is presented for rectilinear layouts but it is extendible to general layouts. As a byproduct we briefly sketch how to speed up the grid method of Wagner and Koren [16].