Nicola Orani

Load swing damping in overhead cranes by sliding mode technique

Moving a suspended load is not an easy task when strict specifications on the swing angle and on the transfer time need to be satisfied. Nevertheless, these type of requirements are always present in industry because they are related to operation safety and cost. Intuitively, minimizing the cycle time and the load swing are conflicting requirements, and their satisfaction requires proper control actions, especially if some uncertainties in the system dynamics are present. In this paper we propose a simple control scheme based on second order sliding modes which is proved to be effective also in the case of poor knowledge of the system dynamics and/or parameters. Such controller has been tested on a laboratory-size model of an overhead crane by means of commercial devices, and some experimental results are reported within the paper.

Fault diagnosis for the vertical three-tank system via high-order sliding-mode observation

This paper presents an approach to the fault diagnosis and disturbance observation for the hydraulic vertical three-tank system. An observer is designed which contains a corrective term based on a second-order sliding mode control algorithm featuring global convergence properties. Thanks to the proposed global observer, the reconstruction of certain faults and/or disturbances can be performed directly from the continuous observer output injection signal, without requiring any filtration. The effectiveness of the proposed method is shown by means of a simulation example and is then validated by performing real experiments.

Fault detection and reconstruction for a three-tank system via high-order sliding-mode observer

This paper presents an approach to the simultaneous faults detection, isolation and reconstruction in the hydraulic vertical three-tank system. An observer is designed which contains a corrective term based on a second-order sliding mode control algorithm featuring global convergence properties. Thanks to the proposed global observer, the reconstruction of certain faults and/or disturbances can be performed without requiring any filtration. The effectiveness of the proposed method is shown by means of a simulation example and then validated by performing real experiments.

Exact reconstruction of actuator faults by reduced-order sliding mode observer

This paper presents an approach to the finite time detection and isolation of actuator faults in a class of nonlinear uncertain systems. After a suitable preliminary state transformation, devoted to put the system dynamics in an appropriate normal form, a reduced-order observer is designed which has an output injection term based on a second-order sliding mode control algorithm featuring global convergence properties. Thanks to the proposed observer, the reconstruction of the actuator faults can be performed exactly and in finite time directly from the observer output injection signal, i.e. without requiring any filtration. The effectiveness of the proposed method is shown by means of a simulation example.

Position/attitude control of a jet-propelled surface-vessel prototype via the simplex-vector sliding-mode approach

This note concerns the design and implementation of a position/attitude sliding-mode controller for a surface vessel prototype. The prototype is equipped with a special, recently patented (V. Arrichiello, et al., 2005), propulsion system based on hydrojets with variable output section. The sliding mode control design is based on the vector simplex method (G, Bartolini, et al., 1997). First we describe the structure and the working principle of the prototype. Then, we present an approximate dynamic model and describe the detailed derivation of the motion controller. Finally, the major implementation issues are discussed and some experimental results are shown

OSCILLATIONS ANALYSIS IN NONLINEAR VARIABLE-STRUCTURE SYSTEMS WITH SECOND-ORDER SLIDING-MODES AND DYNAMIC ACTUATORS

Abstract A class of uncertain systems nonlinear in the input variable and driven by a dynamic actuator device is dealt with. We give sufficient conditions under which the feedback controller based on the “Sub-optimal” second-order sliding-mode control algorithm can guarantee the attainment of a boundary layer of the sliding manifold. The relationship between the actuator parameters and the size of the boundary layer is investigated. We discuss about the possible ways for estimating, or even shaping, the parameters of the periodic limit cycles that may occur in the steady-state within the boundary layer. A simulation example is given that confirm the results of the proposed analysis.