With the advance of digital control hardware the simple but effective proportional-integral-derivative (PID) control technology is moving towards a higher level of performance and robustness. A more general class of variable structure (VS) PID has derived from original PIDs to improve their performances and capabilities. This paper revises the main properties of VS regulators and proposes a novel VS PI controller that combines the advantages of popular PIs with the more flexibility of VS controllers. The proposed regulator is compared with the classic PI over several examples taken from the literature, including first, second and fourth order dynamical systems. An experimental set-up is implemented on purpose using AVR®32 Microcontrollers in a hardware in the loop approach to validate the simulation results in a more realistic environment.

In this paper we describe work being done at our Department to make the Robotics laboratory accessible to students and colleagues, to execute and watch real-time experiments at any time and from anywhere. We describe few different installations, and highlight the underlying philosophy, which is aimed at enlarging the lab in all the dimensions of space, time, and available resources, through the use of Internet technologies.

In the analysis of several scientific and engineering problems nonlinear dynamic systems are modelled as systems composed by the series connection of a linear dynamic subsystem with a nonlinear memoryless unit. If the nonlinearity follows the linear subsystem, the system is called of Wiener type, otherwise the system is called of Hammerstein type. In this work a nonparametric approach to the approximation of Wiener/Hammerstein models is proposed. The approach is based on the use of Laguerre filter banks to approximate the linear subsystem, and an artificial neural network to approximate the memoryless nonlinearity. Building on existing results of approximating properties of Laguerre filters and neural networks, theoretical convergence results of the approximating scheme to the underlining Hammerstein/Wiener model are reported. It is emphasized that the suggested approach requires much milder assumptions than those needed by other procedures previously proposed in the literature. In particular, no knowledge of the linear system order and time delay is needed, and the nonlinearity need not to be invertible and/or of polynomial type.

The problem of driving a Dubin's car (1957) along a given path is considered. In order to model a realistic road-following problem, the car is supposed to move forward only and to have bounds on the turning radius (Dubin's car). We propose a discontinuous control scheme on the angular velocity of the vehicle, based on the theory of sliding modes, that achieves the goal of tracking an unknown path relying on measurements of the current distance from the path and of the heading angle error.