Electroactive soft actuators: Modelling and control

The work done in this master thesis is part of the European project MAGNIFY (1) at the University of Groningen, the Netherlands."MAGNIFY aims to develop a new generation of artificial muscles for robotic systems. The artificial muscle will be realized by using artificial molecular machines, organized in polymer nanofibers and individually controlled by external stimuli''(2) This thesis focuses on a similar polymer that will be used in the project MAGNIFY. The work presents the analysis and utilization of an electroactive soft actuator, made of polyurethane-based nanofibers. A mat of aligned nanofibers of polyurethane and salt has been fabricated through an electrospinning process and, subsequently, has been rolled up to form a bundle of aligned nanofibers. Several electromechanical tests have been performed on the bundle, applying a certain voltage and evaluating the force and the displacement generated by the soft actuator. The sampled data of voltage, force, and displacement are then used to identify the nonlinear model of Voltage-Force and Voltage-Displacement link. The second part of this thesis aims to use the model estimated Voltage-Displacement to build a PID controller for position control. It has been shown a possible future application for the soft actuator as a robotic arm. To conclude, an energy analysis has been performed, to compare the energy consumption of the soft-actuator and of an electric linear motor, considering similar maximum output force. (1)This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no. 801378. (2)https://www.magnifyproject.eu/project-overview