Fractional-order describing function of systems with backlash

This paper analyses the dynamical properties of systems with backlash and impact phenomena based on the describing function method. It is shown that this type of nonlinearity can be analysed in the perspective of the fractional calculus theory.N/

Analysis of Systems with Backlash and Impacts through the Describing Function

This paper analyses the dynamical properties of systems with backlash and impact phenomena based on the describing function method. The dynamics is illustrated using the Nyquist and Bode plots and the results are compared with those of standard models

Comparison of Different Fractional Order PD0.5 Control Algorithm Implementations for Legged Robots

This paper studies different Fractional Order (FO) PD0.5 algorithms applied to the leg joint control of a hexapod robot with two dof legs. For the implementation of the FO PD0.5 joint controllers both the Padé and the series approximations are considered, being compared their performance. For simulation purposes the robot prescribed motion is characterized through several locomotion variables and parameters and for the walking performance evaluation two indices are used, one of them based on the mean absolute density of energy per travelled distance and the other one on the hip trajectory errors. A set of simulation experiments reveals the influence of the different approximations and the order of the PD0.5 controllers tuning upon the proposed indices.N/

Comparison of Different Fractional Order PD0.5 Control Algorithm Implementations for Legged Robots

This paper studies different Fractional Order (FO) PD0.5 algorithms applied to the leg joint control of a hexapod robot with two dof legs. For the implementation of the FO PD0.5 joint controllers both the Padé and the series approximations are considered, being compared their performance. For simulation purposes the robot prescribed motion is characterized through several locomotion variables and parameters and for the walking performance evaluation two indices are used, one of them based on the mean absolute density of energy per travelled distance and the other one on the hip trajectory errors. A set of simulation experiments reveals the influence of the different approximations and the order of the PD0.5 controllers tuning upon the proposed indices.N/

Comparison of different orders padé fractional order PD0.5 control algorithm implementations

This paper studies the performance of different order Padé Fractional Order (FO) PD0.5 controllers applied to the leg joint control of a hexapod robot with two dof legs and joint actuators with saturation. For simulation purposes the robot prescribed motion is characterized through several locomotion variables and for the walking performance evaluation are used two indices, one based on the mean absolute density of energy per travelled distance and the other on the hip trajectory errors. A set of simulation experiments reveals the influence of the different order Padé PD0.5 controllers tuning upon the proposed indices.N/

Discretization of complex-order differintegrals

This paper deals with the discretization of integrals and derivatives (i.e., differintegrals) of complex order. Several methods for the discretization of the operator s, where y = u+jv is a complex value, are proposed. The concept of conjugated-order differintegral is also presented. The conjugated-order operator allows the use of complexorder differintegrals while still resulting in real time responses and real transfer functions. The performance of the resulting approximations is evaluated both in the time and frequency domains.N/

Comparison of different orders padé fractional order PD0.5 control algorithm implementations

This paper studies the performance of different order Padé Fractional Order (FO) PD0.5 controllers applied to the leg joint control of a hexapod robot with two dof legs and joint actuators with saturation. For simulation purposes the robot prescribed motion is characterized through several locomotion variables and for the walking performance evaluation are used two indices, one based on the mean absolute density of energy per travelled distance and the other on the hip trajectory errors. A set of simulation experiments reveals the influence of the different order Padé PD0.5 controllers tuning upon the proposed indices.N/

Analysis of Fractional-Order Discrete Controllers in the Presence of Nonlinearities

Presently, the development of fractional-order controllers is one of the most promising fields of research. However, most of the work in this area addresses the case of linear systems. In this paper we consider the analysis of fractional-order control of nonlinear systems. The performance of discrete fractional-order controllers in the presence of several nonlinearities is discussed. Some results are provided that assesses the superior robustness of such algorithms.N/

Traveled Distance Estimation Algorithm for Indoor Localization

This paper presents an ankle mounted Inertial Navigation System (INS) used to estimate the distance traveled by a pedestrian. This distance is estimated by the number of steps given by the user. The proposed method is based on force sensors to enhance the results obtained from an INS. Experimental results have shown that, depending on the step frequency, the traveled distance error varies between 2.7% and 5.6%

Effect of fractional orders in the velocity control of a servo system

AbstractThe application of fractional-order PID controllers is now an active field of research. This article investigates the effect of fractional (derivative and integral) orders upon system’s performance in the velocity control of a servo system. The servo system consists of a digital servomechanism and an open-architecture software environment for real-time control experiments using MATLAB/Simulink tools. Experimental responses are presented and analyzed, showing the effectiveness of fractional controllers. Comparison with classical PID controllers is also investigated