Cedrat Technologies, innovation in mechatronics

In the context of a more electrical aircraft, in order to explore the feasibility of non usual solutions, electro-fluidic components based on smart materials and new Electro-Hydraulic-Actuators (EHA) concepts, based on active valves and magnetostrictive vibrating pump, have been studied. Active valves based on different magnetostrictive and piezoelectric actuators have been designed, realised, tested and compared. The magnetostrictive version uses a new Amplified Magnetostrictive Actuator (AMA) based on a stack of Giant Magnetostrictive Materials (GMM) and placed inside an elliptical amplification ring.

A moving coil actuator for high precision positioning and compatible with space technology specifications has been designed and successfully tested. General space technology requirements are the use of no degassing material, no lubrication, low mechanic time constant, low electrical power consumption, and thermal energy evacuation through radiating and conducting exchanges (no convection because of operation in vacuum environment). These specifications have been accounted in the design, the realisation and the test of a successful prototype: Thanks to a good design of thermal drains, the actuator presents a high force versus weight ratio.

Piezoelectric actuators find their first applications in active space optics. The purpose of this paper is to describe the state of the art and some applications. Piezo actuators display attractive features for space applications, such as precise positioning, unlubricated, non magnetic and compact features, and low power consumption. However, piezo mechanisms cannot be considered separately from their driving and control electronic.

A design of a single phase step micro motor is presented. The rotor has been optimised to induce the greatest magnetic energy using film permanent magnets. A special study has been performed to select the most advantageous magnetisation direction and the structure has been chosen taking into account micro technologies characteristics and the present know-how available for realisation of prototypes. A scale 2 prototype has already been realised. Its special air gap tuning for film magnet test is presented, as well as first torque measurements.

A tool adaptor with built-in active vibration damping device to dynamically stabilize the turning process is presented in this paper. It can be used in standard CNC-lathes and allows the usage of off-the-shelf tool heads. The vibration compensation system is based on a multilayer piezoactuator that is in collocation with a piezoelectric force sensor. An analogue controller based on the integral force feedback method is used for active damping.

Piezo-electric motors have been successfully developed for various applications like autofocus drives in camera lenses and handling equipment for semiconductor production. Their high speed and accurate positioning capability, combined with a favourable holding torque in unpowered condition, make piezomotors also very attractive for actuation purposes in spacecraft mechanisms. The paper introduces a new concept of a versatile ultrasonic piezomotor. The testing campaign carried out on the designed rotating piezomotor has validated the vacuum compatibility and the lifetime of the motor in air.

Smart actuators and intelligent structures receive a considerable interest in the fields of Air & Space, to realise new functions or more efficient functions than passive structures. In these fields, there are needs for actuation means offering high mechanical energy density (product of stroke and force divided by the mass), a low power consumption, a resistance to severe environment (such as vibrations) as well as other case by case needs : High resolution (embedded active optics for cameras and telescopes), fast response (active control of structures shape, active damping of vibration)…