Magnetostnctive ("MS') technology and Magneto-Rheologlcal Fluid ("MRF") technology are old "newcomers" coming to the market at high speed. Various industries including the automotive industry are full of potential MS and MRF applications. Magnetostrictive technology and Magneto-Rheological Fluid technology have been successfully employed in some low and high volume applications A structure based on "MSm-technology might be the next generation in design for products where power density, accuracy and dynamic performance are key features. Since the introduction of active (MS) materials such as Terfenol-D, \nth stable characteristics over a wide range of temperatures and high magnetoelastic properties, interest in MS technology has been growing. Additionally, for products where is a need to control fluid motion by varying the viscosity, a structure based on MRF might be an improvement in performance. Two aspects of this technology, direct shear mode (used in brakes and clutches) and valve mode (used in dampers) have been studied thoroughly and several applications are already present on the market. Excellent features like fast response, slmple interface between electrical input and hydraulic output make MRF technology attractive for many applications. This dissertation is the introduction of an actuator based on "MS"-technology The possible control arrangement is based on "MR"-technology. The thesis is submitted for the degree of the PhD The dissertation contains the layout definition, analytical calculations, simulations, and design verification and optimization with evaluation of experimental results for the actuator based on "MS"-technology in combination of a possible control device based on "MR"-technology.