1,727 research outputs found
Experimental Characterization of Actuators for Micro Air Vehicles
No full text Mini-UAVs and RC slow flyers require compact, lightweight and responsive actuators. Shape memory alloy wires can be used to design ultra-light micro-servos. This technology relies on the reversible change in crystalline structure that a SMA wire undergoes when electricity runs through it. The resulting contraction is used to deflect the aircraft control surfaces. This paper introduces SMA wires technology and its application to the design of a small-size and light-weight actuator for elevon type controls. A conventional servo is taken as a reference to compare static and dynamic performance of the realized wire configuration prototype. A wind tunnel experiment is set up to test the behavior at different airspeeds and the servos response to variable frequency input is recorded. Extensive data analysis is performed to estimate the system models and to predict their bandwidth. In particular, Prediction-Error Minimization method is applied and Akaike's Final Prediction-Error is used to evaluate the model fitting accuracy. Results show that the SMA servo, despite its excellent general characteristics (i.e. small size, light weight, high power to weight ratio, silent operation, long life) seems to be only partially suitable for small scale flying vehicles due to its low bandwidth. By contrast, the conventional low cost servo provides a faster response in terms of torque output but fails to be accurate and repeatable under dynamic load conditions. </jats:p
Design of a Sliding Mode Control for Wing Rock Suppression in Highly-Swept Wing Aircraft
No full textWing rock is an oscillatory rolling motion which arises at high angles of attack in aircraft with highly-swept wings. In the present paper, a method to suppress wing rock through sliding mode control is proposed. Sliding mode control is designed to minimize together roll angle error and command input through a cost function. The procedure is performed on a wing-only analytical model, the controller is then applied to a complete wing-fuselage model. Simulations include different angles of attack and robustness is assessed using a model altered by parametric disturbances. Results are compared with the behavior obtained by a conventional roll dampe
Are 3D better than 2D Convolutional Neural Networks for Medical Imaging Semantic Segmentation?
No full textIn the last decade, Deep Learning has revolutionized Computer Vision thanks to Convolutional Neural Networks (CNN), that achieved state-of-the-art results in many tasks. In the medical field, imaging techniques, like MRI and CT, are widely used to acquire 3D images of regions that need to be analyzed to identify targets or regions of interest (ROIs). In particular, semantic segmentation is a common image processing task involved in several clinical procedures. When using Deep Learning to solve this task it is possible to either apply a 2D CNN to each slice of the acquired 3D image or apply a 3D CNN to the entire volume acquired. Despite both this approaches have been investigated in the literature, there is neither yet a clear understanding of which one is better (if this is the case) nor a fair comparison of their performances on the same datasets. In this work we aim at making a first step toward to providing an empirical guidance on choosing between 2D and 3D CNNs for medical imaging segmentation. To this purpose we compared a 2D CNN and a 3D CNN based on deep residual U-Net (ResUnet) architecture on different datasets. Our results suggest that the potential benefits of using a 3D CNN are difficult to exploit due to the very limited amount of data that is typically available in medical datasets
Performance evaluation of an L1 adaptive controller for wing-body rock suppression
No full textWing rock is a rolling motion characterized by self-excited oscillations which appears at high angles of attack in aircraft with highly-swept wings. In this paper an analyti- cal model describing this phenomenon is presented for simple wing and wing-fuselage layouts. The parameters of the model were derived through numerical tting of ex- perimental data. For both cases an L1 adaptive controller is applied to suppress the wing rock motion for dierent angles of attack and initial conditions. Adaptation ca- pability is assessed testing the controller action on a model subjected to parametric disturbances. The controller can suppress the motion with satisfactory performance for both congurations, even when disturbe
Maschere e smascheramento
No full textLaboratorio sull’uso della maschera a teatro, organizzato dal Centro Teatro Universitario in collaborazione con Teatro Comunale di Ferrara, condotto da Serena Sartori e Felice Picco, Compagnia Koron Tlé (Centro Interculturale Ricerche Teatrali)
Design and Validation of an Adaptive L1 Controller for Mini-UAV Autopilot
No full textThe dynamics of Unmanned Aerial Vehicles (UAVs) is nonlinear and subject to external disturbances. The scope of this paper is the test of an TeX adaptive controller as autopilot inner loop controller candidate. The selected controller is based on piecewise constant adaptive laws and is applied to a mini-UAV. Navigation outer loop parameters are regulated via PID control. The main contribution of this paper is to demonstrate that the proposed control design can stabilize the nonlinear system, even if the controller parameters are selected starting from a decoupled linear model. The main advantages of this technique are: (1) the controller can be implemented for both linear and nonlinear systems without parameter adjustment or tuning procedure, (2) the controller is robust to unmodeled dynamics and parametric model uncertainties. The design scheme of a customized autopilot is illustrated and different configurations (in terms of mass, inertia and airspeed variations) are analyzed to validate the presented approac
Intra-frame techniques for high-dynamic range CMOS image sensors
No full textHigh Dynamic range is one of the main research fields NeuriCam S.p.A. have been always involved in. This work is an excursus of NeuriCam approaches to this topic
Design and Validation of a L1 Adaptive Controller for a mini-UAV Autopilot
No full textThe dynamics of Unmanned Aerial Vehicles (UAVs) is nonlinear and subject to external disturbances. The scope of this paper is the test of an L1 adaptive controller as au- topilot inner loop controller candidate. The selected controller is based on piecewise constant adaptive laws and is applied to a mini-UAV. Navigation outer loop parameters are regulated via PID algorithm. The main contribution of this paper is to demonstrate that the proposed control design can stabilize the nonlinear system, even if the controller parameters are selected starting from a decoupled linear model. The main advantages of this technique are: (i) the controller can be implemented for both linear and nonlinear systems without parameter adjustment or tuning procedure, (ii) the controller is robust to unmodelled dynamics and parametric model uncertainties. The design scheme of a customized autopilot is illustrated and different configurations (in terms of mass, inertia and airspeed variations) are analyzed to validate the presented approac
High dynamic range CMOS image sensors in biomedical applications
No full textThe biomedical environment is one of the most recent and interesting application fields for CMOS image sensors. Low power consumption, high sensitivity and a simple interface are the main required features; nevertheless high dynamic range can be considered one of the more interesting and less investigated aspects. High Dynamic range is one of the main research fields NeuriCam has been involved in since its incipit. This work is an excursus of NeuriCam’s approaches to this topic
An EMG-informed modelling approach for the prediction of internal variables during locomotion in Parkinson’s Disease patients: a feasibility study
No full text- …
