Many research works have been conducted to investigate active vibration control of underwater structure using
piezoelectric materials for the possible applications in the underwater vehicles and seashore structures. Recently,
advanced anisotropic piezoceramic actuator named as Macro Fiber Composite (MFC) was developed in NASA Langley
Research Center. MFC actuator is consisting of rectangular piezoceramic fibers and interdigitated electrode, which can
provide great flexibility, large induced strain and directional actuating force. In this paper, vibration control performance
of underwater smart hull structure with MFC actuator is evaluated. As a first step, dynamic modeling of underwater hull
structure is conducted by using finite element technique and then modal characteristics of hull structure are investigated.
For the verification of the proposed finite element model, numerical results of modal analysis are compared with those of
experimental modal test results. In order to evaluate vibration control performance, linear quadratic Gaussian (LQG)
controller is designed and experimentally implemented to the system. Control responses are evaluated in the water tank
and presented in both time and frequency domain.
This paper presents force-feedback control performance of a haptic device using a controllable electrorheological (ER)
fluid. A spherical type of joint is devised and its torque characteristic is analyzed by considering Bingham property of
ER fluid. In order to embody a human organ into virtual space, a volumetric deformable object is adopted. The virtual
object is then mathematically formulated by the shape retaining chain linked (S-chain) model. After evaluating reflection
force, computational time, and compatibility with real time control, the virtual environment with the ER haptic device is
established by incorporating reflection force and desired position originated from an organ and master, respectively. In
order to achieve force trajectories at the haptic device in which the force comes from the virtual space, a sliding mode
controller (SMC) is formulated and experimentally realized. Tracking control performances for various operating
conditions are presented in time domain, and their tracking errors are evaluated.