Laura Celentano

Robust tracking method for uncertain MIMO systems of realistic trajectories

Abstract In this paper new results which allow to determine the performances of a given control system with integral action, with uncertain MIMO plant and with reference and disturbance having bounded derivative, are provided. Moreover, other useful theorems are stated to design a controller forcing an uncertain MIMO system to track a generic reference signal with bounded derivative in presence of a generic disturbance with bounded derivative, with prefixed maximum time constant and error. The used approach is based on the determination of a first-order majorant system of an appropriate representation of the control system by calculating the eigenvalues of suitable matrices only in correspondence of the extreme values of the uncertain parameters. The utility and the efficiency of the proposed methods are illustrated with two significant examples.

New Results on Robot Modeling and Simulation

In this paper the possibility of simulating the robot forward dynamics by making use of the inertia matrix and of the kinetic energy gradient only is demonstrated. Such method is shown to be simpler and numerically more efficient than the classical approaches. In the case of planar robots with revolute joints and link centers of mass belonging to the plane containing the rotating axes of the joints, theorems are formulated and demonstrated providing a relatively fast and simple method of calculation for both the inertia matrix and the gradient of the kinetic energy. This allows obtaining a simple and efficient tool to simulate practical robots with rigid links and can also be particularly useful for studying robots with flexible links. By using the proposed approach, the model of a practical planar robot, designed by the computer aided design software package CATIA™, is easily developed and implemented. The simulation results when the gradient of the kinetic energy is computed analytically versus numerically are compared to illustrate that the computational costs are relatively low and the accuracy is high.

Design of a pseudo-PD or PI robust controller to track C2 trajectories for a class of uncertain nonlinear MIMO systems

Abstract In this paper, some theorems are stated, which allow to design robust control laws without chattering, of type PD or PI, for uncertain nonlinear MIMO systems having a quite general structure, to track sufficiently regular trajectories with preassigned maximum error. The proposed control laws are easy to design and implement, above all for the robotic systems, because these laws can also be decentralized and they are based on two design parameters: the first related to the maximum eigenvalue of the inertia matrix from which the practical stability depends on, and the second related to the practical region of asymptotic stability (RAS), to the precision of the tracking error and to the convergence velocity of the tracking error to the desired neighborhood. If the trajectories to track are not sufficiently regular, suitable filtering laws are proposed for these trajectories, so as to facilitate the implementation of the controller and reduce the control action especially during the transient phase. Three significant examples of application in the terrestrial, sea transportation and robotic areas, well showing the simplicity of design and implementation of the controllers and their effectiveness, are reported.

Controller design and experimental validation of a power charging station for e-bike clever mobility

In this paper a suitable digital controller of a RIFT system for e-bike clever mobility is proposed and experimentally validated. Specifically, it is provided a detailed mathematical continuous-time nonlinear model of the system composed of a transformer, a bridge with characteristics of the ideal and real diodes, a filter and a battery, valid for any behavior of the supply voltage. Then, it is provided a suitable discrete-time model of the continuous model to design a digital controller. Finally, it is proposed and experimentally validated a robust discrete-time controller, which allows to charge the battery with a fixed behavior of the current.

Trajectory tracking of a class of uncertain systems applied to vehicle platooning and antenna scanning systems

ABSTRACT The tracking problem is considered for a recurring class of systems, such as the Cartesian robots with real actuators, some transportation systems, and scanning devices used for medical and engineering applications. Some theorems are proved to design a PD type controller, with a possible compensation signal, in order to track sufficiently smooth trajectories with a prescribed maximum error. The developed design methodology is illustrated through two engineering examples. The first example concerns the safety distance control of an electric vehicles fleet. The second example deals with the identification of an antenna scanning system and the prototype design of a new controller that provides better performance than the current one.

Robust controller design of a distributed transport system

The paper proposes a new design method of a distributed controller of an articulated or not transport system, composed of n units, each one driven by an asynchronous motor powered by an inverter. The proposed methodology allows to design a controller that ensures distances between the various units having generic temporal behaviors with bounded derivative and, at the same time, any speed of the head unit with bounded acceleration, despite the action of any disturbances with bounded derivative and the presence of bounded parametric uncertainties. The validity of the method is illustrated with application to an articulated transport system composed of three units.