In this paper a control algorithm is proposed, which provides positive signals to the propeller inputs of a 3 degrees of freedom arm-helicopter system, in consequence the propellers spin only in one direction. The originality of this paper in reference to similar papers, is the fact that preview control algorithms are designed to allow propeller spin in both directions, that bring to the helicopter system a movement acting in the same direction of gravitation force, in practical sense this never happens, because the helicopter system presents an unstable behavior. The proposed algorithm regulates the system angular position using information of angular displacements measurements to generate only positive control signals, and also compensates the unknown friction effects present in the joints of the system. The performance of the algorithm is evaluated using numerical tests, which shows the system stability considering the regulation problem of two degrees of freedom, in the same sense a stability argumentation is presented to validate the control algorithm proposed.
This Article may be found at The IEEE CS Library.
In recent years Fuzzy Logic has been widely adopted as a tool for dealing imprecise data [1] and uncertainty in areas such as control [2,3], Signal Processing and Metrology. However, this tool is usually found at advanced levels of study. Instructional material was developed so that beginning bachelor's as well as technical degree students may familiarize themselves with basic concepts of fuzzy logic. This consists of a Fuzzy Logic Gate kit based on linear Analog Circuitry [4] (Operational Amplifiers, Comparators and Analog Switches) that represent logical operations[5] (AND, OR, NOT) as well as triangular and rectangular membership functions. Three demonstrative examples with a simple implementation were given. Gate response data was obtained using different input signals, as well as different membership functions. [1] Shing & Yang, Neuro Fuzzy and Soft Computing, 1997 [2] Ogata, Modern Control Engineering, 1997 [3] Cirtea, Neural and Fuzzy Logic Control of Drives and Power Systems, 2002 [4] Schilling, Electronic Circuits, 1989 [5] Tocci, Digital Systems Principles and Applications, 2008
Original Title “Kit de Enseñanza de Lógica Difusa”; presented at "Congreso Nacional de Física 2008" as a poster.
Spatial Phase Shifting is an Interferogram Analysis Technique that has the advantages of vibration immunity, permitting the study if transient phenomena. and a simpler implementation. A phase shifting algorithm based on the original Schwider Asynchronous algorithm equations is presented. Our experimental scheme is compared to existing algorithms obtaining favorable results.
*Original Title “Implementación de algoritmo asíncrono de corrimiento de fase espacial para patrones de franjas basado en algoritmo de Schwider”; presented at "Congreso Nacional de Física 2008" as a poster.
The study of sinusoidal fringe patterns is used in more than one optical metrology technique, interferometry and fringe projection being two of them[1]. These permit the measurement of an object without need of contact, thereby avoiding object degradation during the measurement process. There are multiple techniques for fringe pattern analysis[2]. Information is usually obtained when estimating the phase values that make reference signals match the captured image. In this work the "Quadrature Multiplicative Moiré" method proposed by Womack[3] is implemented. This method consists in generating two images, with sine and cosine functions respectively, at the frequency of the carrier of the signal in the captured image. Both are multiplied by the captured image, obtaining two moiré patterns. High frequency components are eliminated from the moirés and phase is extracted from the arctangent of the resulting images. Results are given from applying this technique to real and synthetic images. Results obtained with Takeda's method and the Diagonal Least Squares algorithm are also shown for comparison.[1] Malacara, Optical Shop Testing, 1992 [2] Malacara et. al., Interferogram Analysis for Optical Shop Testing,1998 [3] Schwider, Advanced Evaluation Techniques in Interferometry, Progress in Optics XXVIII, 1990
*Original Title “Implementación de método de Womack”; presented at "Congreso Nacional de Física 2008" as a poster.
