Swimming eel-like robot : design, implementation and validation of a SEA

This master thesis presents the design and implementation of a series elastic actuator (SEA), a torque controlled actuator for an eel-like robot. The SEA has as main component clock springs (a highly deformable spring). It has been developed with fast prototyping tools. The dimensioning was based on the CFD simulation of the swimming eel robot controlled by a central pattern generator (CPG) law. The resulting SEA is compact and lightweight, making it easy to add to the actual floating robot. Furthermore, its static validation shows high linearity and bandwidth only limited by the motor. This work also explores the control of this SEA with a middle-level controller for the torque in the joint and a high-level controller for the angular position. Two versions of this second controller were implemented: a pure feedback law and a feedforward with feedback law. The latter shows a very stable behaviour with low steady state error.