On Trigonometric Formulations of Polynomial Equations

2006 ◽  
Author(s):  
Harvey Lipkin
Keyword(s):  
Real Axis ◽  
Projective Transformation ◽  
Polynomial Equations ◽  
Displacement Analysis ◽  
Kinematic Chains ◽  
Real Roots ◽  
Entire Real Axis ◽  
Half Angle ◽  
Sine Polynomials ◽  
Circular Points

The displacement analysis of open and closed kinematic chains is based on polynomial equations whose variables are functions of relative joint displacements. The objective of this paper is to investigate new and interesting properties of the transformations between the canonical cosine-sine polynomials and the even degree tan-half angle polynomials associated with displacement kinematics. Using a homogeneous coordinate formulation, it is shown that the coefficients of the polynomials are linearly related by a projective transformation whose elements can be defined recursively. The canonical cosine-sine polynomial is then transformed to a cosine or a sine polynomial which can be rooted by usual techniques. However, all real roots are bracketed between −1 and +1 which can have numerical advantages over a corresponding tan-half angle polynomial for which the entire real axis must be searched. It is also demonstrated how polynomial solutions corresponding to circular points at infinity in the tan-half angle, which are typically introduced as extraneous roots via algebraic elimination, may be easily factored out by the transformation to the cosine-sine formulation.

Polynomial Solutions to the Displacement Analysis of 10-Link 1-DOF Mechanisms

1998 ◽  
Author(s):  
A. K. Dhingra ◽  
A. N. Almadi ◽  
D. Kohli
Keyword(s):  
Closed Form ◽  
Solution Process ◽  
Input Output ◽  
Analysis Problem ◽  
Displacement Analysis ◽  
Kinematic Chains ◽  
Polynomial Solutions ◽  
Elimination Procedure ◽  
Half Angle ◽  
Univariate Polynomial

Abstract This paper presents closed-form polynomial solutions to the displacement analysis problem of planar 10-link mechanisms with 1 degree-of-freedom (DOF). Using the successive elimination procedure presented herein, the input-output (I/O) polynomials as well as the number of assembly configurations for five mechanisms resulting from two 10-link kinematic chains are presented. It is shown that the displacement analysis problems for all five mechanisms can be reduced to a univariate polynomial devoid of any extraneous roots. This univariate polynomial corresponds to the I/O polynomial of the mechanism. In addition, one of the examples also illustrates how trigonometric manipulations in conjunction with tangent half-angle substitutions can lead to non-trivial extraneous roots in the solution process. Theoretical conditions for identifying and eliminating these extraneous roots are also presented.

Closed-Form Displacement Analysis of SDOF 8 Link Mechanisms

1996 ◽  
Author(s):  
Abdulaziz N. Almadi ◽  
Anoop K. Dhingra ◽  
Dilip Kohli
Keyword(s):  
Closed Form ◽  
Analysis Problem ◽  
Algebraic Form ◽  
Single Degree Of Freedom ◽  
Displacement Analysis ◽  
Kinematic Chains ◽  
Closed Form Solutions ◽  
Single Degree ◽  
Half Angle

Abstract This paper presents closed-form solutions to the displacement analysis problem of planar 8-link mechanisms with a single degree of freedom (SDOF). The degrees of I/O polynomials as well as the number of possible assembly configurations for all 71 8-link mechanisms resulting from 16 8-link kinematic chains are presented. Three numerical examples illustrating the applicability of the successive elimination procedure to the displacement analysis of 8-link mechanisms are presented. The first example deals with the determination of I/O polynomial for an 8-link mechanism containing no four-bar loops. The second and third examples, address in detail, some of the problems associated with the conversion of transcendental loop-closure equations into an algebraic form using tangent half-angle substitutions. These examples illustrate how extraneous roots can get introduced during the displacement analysis of mechanisms, and how one can derive an I/O polynomial devoid of the extraneous roots. Extensions of the proposed approach to the displacement analysis of SDOF spherical 8-link mechanisms is also presented.

On Graeffe's Method for Complex Roots of Algebraic Equations

1924 ◽  
Vol 22 (2) ◽  
pp. 83-87 ◽  
Author(s):  
S. Brodetsky ◽  
G. Smeal
Keyword(s):  
Nineteenth Century ◽  
Real Axis ◽  
Practical Method ◽  
Algebraic Equations ◽  
Argand Diagram ◽  
Considerable Difficulty ◽  
The Real ◽  
Real Roots ◽  
Bipolar Coordinates ◽  
Complex Roots

The only really useful practical method for solving numerical algebraic equations of higher orders, possessing complex roots, is that devised by C. H. Graeffe early in the nineteenth century. When an equation with real coefficients has only one or two pairs of complex roots, the Graeffe process leads to the evaluation of these roots without great labour. If, however, the equation has a number of pairs of complex roots there is considerable difficulty in completing the solution: the moduli of the roots are found easily, but the evaluation of the arguments often leads to long and wearisome calculations. The best method that has yet been suggested for overcoming this difficulty is that by C. Runge (Praxis der Gleichungen, Sammlung Schubert). It consists in making a change in the origin of the Argand diagram by shifting it to some other point on the real axis of the original Argand plane. The new moduli and the old moduli of the complex roots can then be used as bipolar coordinates for deducing the complex roots completely: this also checks the real roots.

Forward and Inverse Displacement Analysis of an Actuated Spoke Wheel Robot With Two Spokes and a Tail Contact With the Ground

2010 ◽  
Author(s):  
Ping Ren ◽  
Dennis Hong
Keyword(s):  
Design Optimization ◽  
Ground Motion ◽  
Numerical Solutions ◽  
Convex Surface ◽  
Polynomial Equations ◽  
Surface Geometry ◽  
Displacement Analysis ◽  
Unstructured Environments ◽  
Straight Line ◽  
Rigid Shell

Intelligent Mobility Platform with Active Spoke System (IMPASS) is a unique wheel-leg hybrid robot that can walk in unstructured environments by stretching in or out three independently actuated spokes of each wheel. The latest prototype of IMPASS has two actuated spoke wheels and one passive tail. In order to maintain its stability, the tail of the robot is designed as a rigid shell with a geometrically convex surface touching the ground. IMPASS is considered as a mechanism with variable topologies (MVTs) due to its metamorphic configurations. Its motions on the ground, such as steering, straight-line walking and other combinations, can be uniformly interpreted as a series of configuration transformations. Among all cases of its topologies, the cases with two spokes and the tail in contact with the ground possess two d.o.f and contribute the most to its ground motion. To fully understand the characteristics of such topologies, the forward and inverse displacement analysis is developed for these cases, with the polynomial equations derived. Numerical solutions from simulation are present to validate their formulation. These results lay the kinematics foundation for the motion monitoring and planning of IMPASS. It also contributes to the design optimization of the tail’s surface geometry to improve its adaptability on uneven terrains.

scholarly journals Solutions of Linear Impulsive Differential Systems Bounded on the Entire Real Axis

2010 ◽  
Vol 2010 (1) ◽  
pp. 494379 ◽  
Author(s):  
Alexandr Boichuk ◽  
Martina Langerová ◽  
Jaroslava Škoríková
Keyword(s):  
Real Axis ◽  
Differential Systems ◽  
Entire Real Axis ◽  
Impulsive Differential Systems

25.—Spectrum of a Third-order Differential Operator with Large Coefficients

1975 ◽  
Vol 72 (4) ◽  
pp. 299-305
Author(s):  
K. Unsworth
Keyword(s):  
Differential Operator ◽  
Differential Expression ◽  
Real Axis ◽  
Sufficient Conditions ◽  
Order Differential Operator ◽  
Third Order ◽  
Minimal Operator ◽  
The Third ◽  
Entire Real Axis

SynopsisThis paper sets out to study the spectrum of self-adjoint extensions of the minimal operator associated with the third-order formally symmetric differential expression. The technique employed is the method of singular sequences. Sufficient conditions are established on the coefficients of the differential expression in order that the spectrum should cover the entire real axis. Particular cases in which the coefficients behave roughly as powers of x as the magnitude of x becomes large are then considered, and certain conclusions are drawn regarding the spectra under different restrictions on these powers of x.

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