1,721,012 research outputs found
An Active Vibration Isolator Based on an Electromagnetic Actuator.
No full textThis paper presents a vibration isolation system based on elastomeric mounts acting together with an electromagnetic actuator that can provide a force that, depending on the operating conditions, can amplify or attenuate the overall restoring force. Therefore, the device would have the advantage of behaving like a normal passive isolation system but, if necessary, its reaction can be controlled.
To evaluate its effectiveness an isolator prototype was realized; it is constituted by three coils, two of which are placed on the ground while the last one is fixed on isolated structure. The tests were performed considering a unidirectional motion. In the paper, the experimental setup is described and the test results are presented and commente
Mutual coupling compensation in a power synthesis technique of planar array antennas
No full textApril 200
Planar shorted annular antenna
No full textA new type of annular patch antenna is presented. At variance of classical annular patch antenna the inner cylindrical wall is metallized. It radiates as a circular patch but has a smaller stored energy and the feed point can be chosen to have an easy matching. A cavity model approach of the patch antenna is presented; the theoretical results are compared with the experimental ones
Mutual coupling compensation in a power synthesis technique of planar array antennas
No full textApril 200
Electromagnetic-mechanical coupling in the magneto-rheological elastomerselastomers: An experimental overview
No full textThis paper describes an extensive experimental characterization conducted on Magneto-rheological elastomers (MRE) that are composite materials with magnetically polarized particles dispersed in an elastomeric soft matrix. The mechanical and rheological properties of these materials, that are an important branch of the smart material family, can be reversibly changed upon exposure to a magnetic field. This multi-physics coupling shows also an inverse effect and is named pseudo-Villari effect. So MREs show a dependence of magnetic induction field of a material on mechanical stress/strain. The manuscript focuses on isotropic and particles-oriented samples with 25% particles’ percentage volume. The samples are subjected to shear periodic loads, varying both the amplitude and the frequency of the excitation, as well as the magnetic field. Results show that the isotropic pads have a negligible electromagnetic-mechanical coupling effect, while, the pads with oriented particles present a high coupling both for the direct and the inverse effect
Six-Wheeled Mobile Manipulator for Brush Cleaning in Difficult Areas: Stability Analysis and Grip Condition Estimation
Full text linkThis paper aims to analyze a six-wheeled mobile manipulator as a solution for brush clearing difficult areas. To this end, a rover with a rocker–bogie suspension system, like those used for space explorations, is considered; the cutting head is moved by a robotic arm fixed to the rover so that it can reach areas to clean in front of the rover or on its sides. The change of the pose of the robotic arm shifts the centre of mass of the rover and, although the shift is not important, it can be used to improve stability, to overcome an obstacle, or to change the load distribution between the wheels to prevent the wheels from slipping or sinking. Some analyses of the interaction between the rover and robotic arm are reported in this paper. To prevent the rover from entering a low-grip area, the possibility of estimating the grip conditions of the terrain is considered, using the front wheels as tactile sensors. By keeping the rear wheels stationary and gradually increasing the torque on the front wheels, it is possible to evaluate the conditions under which slippage occurs. In case of poor grip, using the other drive wheels, the rover can reverse its direction and look for an alternative path
A Feasibility Analysis of a Six-Wheel Drive Rover for Bush Clearing Operations
No full textThe paper deals with the possibility of adopting an autonomous mobile robot for brush cutting in areas characterized by strong surface irregularities. The robot consists of a rover with six-wheel drive and equipped with rocker bogie suspension to operate on rough terrain. The cutting head can reach surfaces adjacent to the rover being the end effector of a manipulator mounted on the rover. The manipulator can position the cutting head in front or to the side of the rover; the latter pose can reduce the risk of robot rollover on paths with strong transversal slopes. This type of mobile robot can be useful for clearing bushes such as those located at the edges of cultivated fields as, compared to traditional tracked vehicles, they have the advantage of not emitting polluting gases, of having a greater ability to move on very irregular soils, of have lower production and maintenance costs
Cinematica e dinamica del corpo rigido
No full textIl testo si propone di dare una preparazione introduttiva al corso di meccanica applicata alle macchine le cui problematiche fanno spesso ricorso ai concetti teorici riguardanti la cinematica e dinamica del corpo rigido.
In esso tali argomenti vengono infatti trattati in una forma classica, con l'intento di privilegiare gli aspetti concettuali rispetto a quelli numerici, questi ultimi in genere preferiti nei testi di cinematica e dinamica dei sistemi multibody (corpi rigidi)
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