268 research outputs found
On Brushless Motors Continuous Duty Power Rate
No full textThe “continuous duty power rate” of a brushless motor is a coefficient that characterizes its ability to accelerate a load. For this reason it is also called “accelerating factor” and playes a considerable role in the choice of the motor to be used in an automatic machine. This work is focused on the analysis of this parameter, defined for each motor as the ratio between the square of the motor nominal torque and its momentum of inertia: it is exclusively defined by parameters related to the motor and, therefore, it does not depend on the machine task. The research is carried out through a database containing the main electromechanical features of some commercial motors and their “accelerating factors”. Using the collected information, related to more than 300 brushless motors, some graphs are produced showing how motors having the same size can have different accelerating factors or, conversely, how same accelerating factors can be obtained through different electro-mechanical design.</jats:p
THE GENERALIZED JACOBIAN MATRIX AND THE MANIPULATORS KINETOSTATIC PROPERTIES
No full textManipulator kinetostatic performances are usually investigated considering only the geometrical structure of the robot, neglecting the effect of the drive system. In some circumstances this approach may leads to errors and mistakes. This may happen if the actuators are not identical to each other or when the employed transmission ratio are not identical and/or not constant. The paper introduces the so called “Generalized Jacobian Matrix” obtained identifying an appropriate matrix, generally diagonal, defined in order to: 1. properly weigh the different contributions of speed and force of each actuator. 2. describe the possible non-homogeneous behaviour of the drive system that depends on the configuration achieved by the robot. Theoretical analysis is supported by examples highlighting some of the most common mistakes done in the evaluation of a manipulator kinetostatic properties and how they can be avoided using the generalized jacobian matrix.</jats:p
Biomimetic design of an underwater robot inspired to the cownose ray
No full textThis paper shows the design of an underwater autonomous robot. The challenges of this activity are mainly linked to motion design and to energy
efficiency. Therefore, a bioinspired approach has been used. Batoid fishes swim moving their pectoral fins, they produce a wave travelling in the direction opposite to their motion, pushing water backwards and gaining thrust as a consequence of momentum conservation. The motion
of the fin has been studied and reproduced with a series of articulated mechanisms. In this work the optimization of the mechanism’s geometry is described and the experimental results on the reconstructed fin are presented
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