Modeling and control strategies for a variable reluctance direct-drive motor

A high-performance ripple-free dynamic torque controller for a variable-reluctance (VR) motor intended for trajectory tracking in robotic applications is designed. A modeling approach that simplifies the design of the controller is investigated. Model structure and parameter estimation techniques are presented. Different approaches to the overall torque controller design problem are discussed, and the solution adopted is illustrated. A cascade controller structure consisting of a feedforward nonlinear torque compensator, cascaded to a nonlinear flux or current closed-loop controller is considered, and optimization techniques are used for its design. Although developed for a specific commercial motor, the proposed modeling and optimization strategies can be used for other VR motors with magnetically decoupled phases, both rotating and linear. Laboratory experiments for model validation and preliminary simulation results of the overall torque control system are presente

A prototype controller for variable reluctance motors

A three-level cascade structure is proposed for the control of a variable reluctance (VR) motor. In order to deal with the highly nonlinear behavior of VR motors, the controlling system includes two variable-structure controllers for current and velocity loops as well as an intermediate torque-sharing compensator. The intermediate compensator has been designed by means of nonlinear optimization techniques in order to reduce the torque ripple and to get the maximum motor velocity. The proposed controller has been validated through extensive simulation experiments. The architecture of a prototype controller is presented and the actual performance measured on a VR motor is discussed in comparison with simulations. The results show practical feasibility and good performance of the proposed controller, which is also suitable for a very simple and quite inexpensive fully hardware implementatio

Real-Time Forecasting of Air Pollution Episodes in the Venetian Region. Part I: The Advection-Diffusion Model. Part II: The Kalman Predictor

The object of this overall research, which has an expected duration of two years is to set up a scheme for predicting ground-level pollutant concentrations for real-time control purposes (i.e. the action to be taken at the emission sources in the presence of forthcoming high pollutant events). The forecasting scheme is described, together with its application to sulphur dioxide pollution in the Venetian lagoon area. The scheme is based on a complex mathematical model to be run on a computer and receiving at the beginning of each interval of time all the information (about the meteorological and emission situation) required for the prediction. The type of control action which should be taken on the basis of such a forecast is the object of this part of the research

DTM-based morphometry of the Palinuro seamount (Eastern Tyrrhenian Sea): Geomorphological and volcanological implications

We present a high resolution DTM of the Palinuro Seamount (PS, Tyrrhenian Sea, Italy) resulting from the processing of multibeam swath bathymetry records acquired during the second leg of the “Aeolian 2007” cruise. PS consists of several superimposed volcanoes aligned along a N100°E strike and measures 55×25 km. The western and the central sectors result from the coalescence of collapse structures (calderas) with younger volcanic cones. The eastern sector reveals a more complex and articulated structure. In the central sector, a volcanic crater with a well-preserved rim not obliterated by erosional events suggests a volcanological rejuvenation of this sector. The presence of flat surfaces on the top of the seamount may be due to the formation of marine terraces during the last sea-level lowering. Lateral collapses on the northern and southern flanks of the seamount are probably related to slope instability, as suggested by the presence of steep slopes (25–40°). The main fault affecting PS strikes N65°E and shows a right lateral component of movement. E–W and N10°E striking faults are also present. Assuming that theN100°E deep-seated fault,which is responsible for theemplacement of PS,movedwith sinistral slips, we interpret the N65°E and the N10°E faults as right-lateral (second order) shear and left-lateral (third order) shear, respectively. Due to the particular location of the Palinuro Seamount, the data presented here allow us to better understand the volcanism and the geodynamic processes of the Tyrrhenian Sea

DTM-based morphometry of the Palinuro seamount (Eastern Tyrrhenian Sea): Geomorphological and volcanological implications

We present a high resolution DTM of the Palinuro Seamount (PS, Tyrrhenian Sea, Italy) resulting from the processing of multibeam swath bathymetry records acquired during the second leg of the “Aeolian 2007” cruise. PS consists of several superimposed volcanoes aligned along a N100°E strike and measures 55×25 km. The western and the central sectors result from the coalescence of collapse structures (calderas) with younger volcanic cones. The eastern sector reveals a more complex and articulated structure. In the central sector, a volcanic crater with a well-preserved rim not obliterated by erosional events suggests a volcanological rejuvenation of this sector. The presence of flat surfaces on the top of the seamount may be due to the formation of marine terraces during the last sea-level lowering. Lateral collapses on the northern and southern flanks of the seamount are probably related to slope instability, as suggested by the presence of steep slopes (25–40°). The main fault affecting PS strikes N65°E and shows a right lateral component of movement. E–W and N10°E striking faults are also present. Assuming that theN100°E deep-seated fault,which is responsible for theemplacement of PS,movedwith sinistral slips, we interpret the N65°E and the N10°E faults as right-lateral (second order) shear and left-lateral (third order) shear, respectively. Due to the particular location of the Palinuro Seamount, the data presented here allow us to better understand the volcanism and the geodynamic processes of the Tyrrhenian Sea

Open-slope, translational submarine landslide in a tectonically active volcanic continental margin (Licosa submarine landslide, southern Tyrrhenian Sea)

The southern Tyrrhenian continental margin is the product of Pliocene-Recent back-arc extension. An area of approximately 30 km of gentle (about 1.5°) lower slope of the last glacial outer shelf sedimentary wedge in water depths of between 200 and 300 m failed between 14 and 11 ka BP. We approached the landslide by multibeam and sub-bottom profiler surveying, high-resolution multichannel seismics, and coring for stratigraphic and geotechnical purposes. With regard to a slope-stability analysis, we carried out an assessment of the stratigraphic and structural setting of the area of the Licosa landslide. This analysis revealed that the landslide detached along a marker bed that was composed of the tephra layer Y-5 (c. 39 ka). Several previously unknown geological characteristics of the area are likely to have affected the slope stability. These are the basal erosion of the slope in the Licosa Channel, a high sedimentation rate in the sedimentary wedge, earthquake shaking, the volcanic ash nature of the detachment surface, subsurface gas/fluid migration, and lateral porewater flow from the depocentre of wedge to the base of the slope along the high-permeability ash layers. A newly discovered prominent structural discontinuity is identified as the fault whose activity may have triggered the landslide

The Control System of the U.B. Hand II: an Overview of the Hardware Design and Implementation

The paper describes the control system of the University of Bologna Robotic Hand

Real-time forecast of air pollution episodes in the Venetian region. Part 2: The Kalman predictor

Real-time prediction of air pollution means forecast of future ground-level concentrations on the basis of current information about meteorology, emission and concentrations themselves. The paper illustrates how the episode forecast performance of the advection-diffusion model (described in Part 1) can be improved by: (i) embedding the model into a stochastic version, by introducing into the numerical solution scheme of the advection-diffusion equation proper random terms (noises), specified in a statistical sense and representative of all the inaccuracies of the model itself (wrong inputs, numerical errors, simplifications of the actual physical mechanism, ...); (ii) applying the well-known Kalman prediction technique for real-time forecast to such stochastic version of the model. The results of such a procedure have been satisfactory in the case of the Venetian lagoon sulphur dioxide pollution. In particular, the four-hour ahead forecasts of episodes have been drastically improved with respect to those obtained by means of the "deterministic predictor" illustrated in Part 1