dc.description.abstract | This thesis deals with the measurements, modeling, and the demonstration of a conducting polymer transducer for robotic applications. As a subfamily of electroactive polymers, conducting polymer has advantages of low operating voltage, large deformation capabilities, ease of manufacturing, and integration within the micro-electro-mechanical system (MEMS). Because of a reversible electrochemical process, conducting polymers can be used as actuators or mechanical sensors. In this work, we investigate a PEDOT-based conducting polymer with the architecture of interpenetrating polymer networks (IPN) from a robotic perspective. Thanks to the pseudo-trilayer compact structure, this conducting polymer is promising for applications of great interest in soft sensors and soft actuators at the macro- or microscale.
The behaviors and performances of the conducting polymer transducer as a bending actuator and as a bending sensor are investigated, respectively. Two working modes, namely actuation and sensing, are identified through modeling and experimental validations. With the experiments and validations, the performances of the slender-shape bending polymer actuator, including the free displacement and the output force, are characterized based on the mechanical model. Mathematical derivation and measurements are employed to identify the parameters. The results show the tip displacements and the forces of the bending actuators versus time, position, and given voltage. The electrical responses of the bending polymer sensors in different bending conditions are measured. Analytical functions of electrical responses are derived in order to identify the sensing outputs and the parameters of the model. The capability of the electrical model to predict the output voltage of the bending sensor versus time in a good agreement with experiments is shown in the study. Besides, the sensing signal drops over time, especially in quasi-static mechanical deformation. It is characterized based on modeling, and a compensation method is proposed to balance the decreasing voltage of the polymer sensor.
To demonstrate both the functions to sense and actuate achieved within the same material, a soft gripper made of two polymer fingers (one active and one passive) is presented in this thesis. This is a promising first step towards more complex 3D structures. The gripping force of the active finger can be set with the driving input and estimated by the proposed mechanical model. The passive finger of the gripper outputs a sensing signal when grasping an object, which is useful to monitor the contact with the object and to control the gripper in closed-loop. A sphere was successfully lifted in the experiment, and we were able to detect the gripping phase and the time when the contact was broken. The gripping force was monitored with the corresponding sensing output by the linear model of the polymer sensor. | en_US |