Multi degree of freedom (dof) mechanisms are widely required into micro or macro manipulation fields as well as in optronics functions. Commonly available mechanisms may be divided into two main categories. The first is industrial robots (serial or parallel). These offer large range of motion, in rotation and translation. Their resolution is usually limited in the sub-millimeter range. The second category achieves very high resolution motion (sub-nanometer) but is limited to a few decades of microns. A way to combine both long stroke and resolution is to use piezo motors into multi dof mechanisms. The aim of this paper is to present a combination of both advantages into a low volume tripod actuator. The Tripod Actuator by Cedrat Technologies (TrAC) is a 3 dof mechanism offering +/-35° rotation around X and Y axis and a 10mm Z translation stroke into a low volume of Ø50x50mm.
Many past and on-going studies are focusing on the use of piezo-actuators for aeronautical applications. One of the trendiest topics is the use of such devices for active flow control in aircraft, in order to reduce fuel consumption and noise. However, the implementation of such systems in aircraft suffer a lack of maturity with respect to aeronautical constraints, which are: high efficiency, compactness, and lightweight. In general, the actuators are composed of ceramics integrated in a metallic shell, which makes them heavy. For driving the actuators, the power amplifiers employed are usually linear amplifiers, which have a poor efficiency, leading to bulky designs due to large heatsinks. This paper presents recent developments that have been made to cope with these issues in order to obtain a piezo-actuation chain suitable for aeronautical applications.
In the frame of the Meteosat Third Generation project (MTG), the future European Operational Geostationary Meteorological Satellites system, Cedrat Technologies has developed a dedicated actuator for the Scan Assembly mechanism (SCA) made by SENER. Such motors are needed to actuate the SCA on the north/south (N/S) and east/west (E/W) axes. The requirement of precise pointing of the SCA induces very specific characteristics for the motorisation. The motor needed characteristics are: to be free from any cogging, high constant motor [N.m/√W] to have a constant torque over full stroke range, to have a very low hysteresis and to have redundant coils. To meet these stringent requirements, the choice was made to develop a specific Rotating Voice Coil Motor.
Actuators in space are broadly used to operate satellites’ platform and payload devices. Despite their common utilisation, actuators still represent critical subsystems as their failure might often lead to severe, when not catastrophic, effects on the spacecraft operations. Environmental conditions to which actuators are exposed in space are generally not favourable: operating temperature ranges and deep vacuum are certainly the most critical ones.
Nowadays, piezoelectric actuators (PA) are used in fast power actuations and high power applications as requested in machine tools or helicopters flap applications. Regarding to the low power capability and high loss ratios of linear amplifiers, Switching Power Amplifiers (SA75X) is designed by Cedrat Technologies to drive piezoelectric actuators in such applications. The switching technique (up to 100 kHz) allows high current peaks required by impulse or by high frequency applications on large piezoelectric actuators (or actuators in parallel) and allows energy harvesting.
In the context of the ATLID instrument  embedded in the EarthCARE mission (Earth Cloud, Aerosol and Radiation Explorer), a Beam Steering Assembly is deviating a pulsed high energy UV laser beam to compensate the pointing misalignment between the emission and reception paths of ATLID with a very high stability and high resolution. Within the EarthCARE mission, led by ESA, Astrium is responsible for the ATLID instrument. The BSA development, manufacture and tests were assigned by Astrium to Sodern, an EADS filial.
Future aeronautics will more often use electrical actuators in order to replace hydraulic actuators. Existing Amplified Piezo Actuators APA® with steel shell, delivering among the highest mass energy densities, are good candidates. Lighter carbon shells are developed to further increase their efficiency. For helicopters rotor blade application this evolution is almost unavoidable but is also very interesting for other domains. High modulus and high tensile strength carbon fibres shells have been produced by conventional filament winding, tested and compared.