Modelagem e caracterização de um atuador termomecânico baseado em fios de nylon.

Abstract

The present work aimed to characterize and model a thermomechanical actuator based on monofilament nylon yarn. To this end, a platform was developed to subject the nylon thread to a torsion-induced spring formation process, which gives the wire the actuator characteristic capable of generating a linear displacement when subjected to a temperature difference. The actuator model was divided into two dynamics, the first is a thermoelectric model, whose input is electric current and the output is the temperature difference; and the second is a thermomechanical model, whose input is the di- temperature difference and the output is the displacement. To activate the actuator by heating resistance and collect data on electric current, temperature, force and displacement, was An experimental platform was designed and built using Model Based methodologies Design, automatic code generation and Model V for hardware development and software. The platform was validated through an isometric test and an isobaric test, which demonstrated that an actuator of 120 mm in length and 3 mm in diameter is capable of lifting a load of 150 g, contracting up to 15.2 mm (12.7 %), and generating a force up to 2.36 N when subjected to a temperature of 156.4 ◦C in response to a signal of 6.6 A average electrical current input controlled by PWM that traveled a 0.8 mm enamelled copper wire wrapped around the actuator. To estimate the parameters of the models, the least squares and least squares method were used recursive with data obtained from an isobaric experiment with input signal with shape of PRBS wave. For model validation, the temperature and displacement outputs were calculated using the estimated parameters and the electrical current data obtained of isobaric experiments with square, triangular waveform input signals and sinusoidal, and compared with the measured temperature and displacement signals. To- of the calculated mean square errors had an amplitude of less than 3% in relation to maximum amplitude of the measured signals, thus validating the models. were calculated the author relations between residues, which validated the thermomechanical model, but did not validate the thermoelectric, indicating that there are dynamics not included in the model. Keywords: nylon actuator, characterization, experimental modeling.