Qadralimb: Embedded TCP Actuators in Silicone for Grasping Tasks and Underwater Soft Robots




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There have been several advancements made in the field of soft robotics in the past few years using different actuators. One of these advancements has been in the application of TCP (Twisted and Coiled Polymers) as artificial muscles. TCP actuators embedded in silicone have several advantages i.e. they are quiet, they use low voltage and can be tailored using various parameters to produce desired shapes. Initially, one type of TCP actuators, the 2-ply muscles were characterized for static and dynamic behaviors, to determine and get some insight on the stiffness and strain of the muscles. The behaviors of TCP actuators embedded in silicone depend on several critical parameters such as applied voltage, actuation frequency, degree of pre-tension, strain, and resistance of the muscle, as well as the geometry and the material composition of the elastomer structure. Out of these, the first three parameters can be controlled during operation. This thesis presents experimental results that determine the optimum ranges for these controllable parameters and characterizes their behavior specifically for an underwater robot and grasping of objects for use in robotic manipulators. A prototype robotic structure with four limbs that can swim a vertical displacement of 340 mm in 600 s was demonstrated. Moreover, the limb actuation conditions, have also been optimized for grasping applications wherein objects of different shapes, sizes and weights have been grasped in air and in water against gravity using a single limb of size 140x 60x 5 mm3. Here, the limb was able to hold a maximum load of 35 g object against gravity when operated in air. Furthermore, the thesis shows certain FEM simulation results of a single limb which was done using ANSYS and comparison with experimental results. These results have several potential applications in the field of underwater exploration, manipulation in environments that are toxic for human interaction.



Robotics, Autonomous robots, Automatic control