Geometrical Kinematic Analysis of a Planar Serial Manipulator Using a Barycentric Formula

The kinematics, instantaneous motion, and statics of a manipulator have recently been determined algebraically. In the past, such studies did not provide any intuition about the equation. Robot designers had to use a numerical method or trial-and-error solver with unintuitive equations. Alternatively, all algebraic processes have their own geometrical meaning. Geometric analysis provides intuition for designing the linkages of a robot. Screw theory and barycentric formulas are used to find meaningful geometric measures. The kinematics and statics of a manipulator are described by an axis screw and its reciprocal line screw. The barycenter of a triangle with edges and a perpendicular distance between the two screws are useful geometric measures for geometric analysis. This study provides a geometric interpretation of the kinematics and statics of a planar manipulator using a barycentric formula.

Hermite Interpolation on the Unit Circle Considering up to the Second Derivative

The paper is devoted to study the Hermite interpolation problem on the unit circle. The interpolation conditions prefix the values of the polynomial and its first two derivatives at the nodal points and the nodal system is constituted by complex numbers equally spaced on the unit circle. We solve the problem in the space of Laurent polynomials by giving two different expressions for the interpolation polynomial. The first one is given in terms of the natural basis of Laurent polynomials and the remarkable fact is that the coefficients can be computed in an easy and efficient way by means of the Fast Fourier Transform (FFT). The second expression is a barycentric formula, which is very suitable for computational purposes.