Cedrat Technologies, innovation in mechatronics

MRF actuators are new electromechanical components using Magneto Rheological Fluids (MRF). When submitted to a high enough magnetic field, MRF switch from a liquid to a near solid body. These new developed MRF actuators were developed in order to reach three aims: to offer a blocking force at rest which can be strongly reduced by applying a current, to provide an electrically-controllable resistive force over a stroke of 30 mm, to perform the control of the force in a very short time, typically in a few milliseconds.

To meet the demand of controllable millimeter-stroke actuators, there are two possible starting points. One is to consider improvement of moving coil actuators, the other is to consider improvement of moving iron actuators. Following this approach and using its experience on the different types of magnetic actuators, Cedrat Technologies has developed new specific Moving Iron Controllable Actuators, called MICA. This actuator circumvents previous controllability limitations of standard Moving Iron actuators while keeping their high forces capabilities. Compared with moving coils of the same force, the MICA are twice less in mass while requiring 3 times less electric power. Another significant advantage of the MICA is a much better heat dissipation and reliability as the MICA coil is fixed into the iron stator.

Short Abstract The MRF actuators are new electromechanical components using Magneto Rheological Fluids (MRF). When submitted to a high enough magnetic field, MRFs switch from a liquid to an almost solid body. The purpose of the new developed MRF actuators is to reach three aims: to offer a blocking force at rest, which can be strongly reduced by applying a current, to provide an electrically- controllable resistive force over a stroke of 30 mm, to perform the control of the force in a very short time, typically in a few milliseconds.

As part of the Lisa Technology Package (LTP) on board the LISA-PATHFINDER spacecraft, the LISAPATHFINDER interferometer is of the heterodyne Mach-Zehnder type. It requires as input two light beams derived from the same source but with a small frequency difference (a few kHz). These two optical beams are produced in the Laser Assembly (LA) via the "Laser Modulation Unit" (LMU). The LMU includes an optical bench, two Acousto-Optic Modulators and two Optical Delay Lines [1].

Most of present electric contactors use magnetic actuators of reluctant type (so called electromagnets) that are supplied with a simple voltage source. The use of a reluctant actuator in this condition leads to a considerable force increase when the magnetic circuit is closing, which creates damaging rebounds of the electrical contacts. To have a better control of the closing dynamics, we develop an electric drive method to reduce impact speed and to improve the closing dynamics. In this method, the reluctant actuator structure is unchanged. The appropriate current shape to be injected into the actuator is determined using a calculation method.

Since many years the field of active controls of vibration is growing up and a lot of new applications using smart actuators are developed. In the following study, these concepts are adapted and applied on a general structure of ski to damp the large modes of vibrations keeping the robustness of the control and the static loads during the ride.. Simulations integrating FEM models coupling to electromechanical model were elaborated to obtain the principal performances and to study the stability of the loop.

In the aicrft vehicle, a part of the produced energy is transformed into mechanical vibration energy losses. This rue is more than ever true when the need for electrucal energy is a crucial problem. So, systems which are able to transform the mechanical energy in a scavenged electrical energy are very interesting.