Abstract-An autonomous underwater vehicle with a biomechanical propulsion system is a possible answer to the demand for small, silent sensor platforms in many fields. The design of Galatea, a bio-mimetic AUV, involves four aspects: hydrodynamic shape, the propulsion, the motion control systems and payload. The shape of the hull is based on a modified Wortmann FX 71-L-150/20 airfoil. Wind tunnel tests have been conducted to determine the hydrodynamic force coefficients. The propulsion system is based on bio-mimetic undulating fin propulsion. A test set-up is build to get more insight in the fundamentals of this mechanism. The swimming behaviour is currently manually controlled and will be developed into an fully autonomous system. In the future, more research on the undulating fin propulsion system will be carried out and a second, modular prototype robot will be developed.

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The dynamic response of a new class of flight control actuators that rely on post-buckled precompressed (PBP) piezoelectric elements is investigated. While past research has proven that PBP actuators are capable of generating deflections three times higher than conventional bimorph actuators, this paper quantifies the work output and power consumption under various axial loads, at various frequencies. An analytical model is presented that supports the experimental findings regarding the increasing work output and natural frequency shift under increasing axial loads. Furthermore, increasing axial loads shows an increase in open-loop piezoelectric hysteresis, resulting in an increasing phase lag in actuator response. Current measurements show an electromechanical coupling that leads to power peaks around the natural frequency. Increasing axial loads has no effect on the power consumption, while increasing the work output by a factor of three, which implies a significant increase in work density over the piezoelectric material itself.