Cedrat Technologies, innovation in mechatronics

The article describes a linear magnetic flip-flop micro actuator, designed with FLUX software, assembled and characterised for a specific application requiring low losses at function states. The micro size allows reducing the energy required for actuation. Permanent magnets ensure bistability and suppress losses at functional states. Although the actuator is less than 1 g, the blocking force is about 0.1N and the stroke is 0.6mm. Firstly, the paper describes the main functionality of the actuator. Then are presented measured characteristics and results are compared with FLUX software computation. Finally perspectives of further miniaturisation are discussed.

Piezomotors are well known in various applications where high precision actuation is required like AFM or handling equipment for semiconductor production. Their specific low speed in direct drive and high torque characteristics combined with high holding torque in off power conditions make them very attractive for any positioning application and especially space mechanisms where low electrical consumption is always sought. A new concept of rotating stepping piezomotor has been developed in the frame of the LISA space project where the mechanism of the telescope orientation was addressed.

Magnetostriction occurs in the most ferromagnetic materials and leads to many effects [1,2]. The most useful one to refer to is the Joule effect. It is responsible for the expansion (positive magnetostriction) or the contraction (negative) of a rod subjected to a longitudinal static magnetic field. In a given material, this magnetostrain is quadratic and occurs always in the same direction whatever is the field direction. Giant Magnetostrictive Materials (GMM), especially Rare earth-iron discovered by A.E.Clark [3], feature magnetostrains which are two orders of magnitude larger than Nickel. Among them, bulk Tb0.3Dy0.7Fe1.9, called Terfenol-D, presents the best compromise between a large magnetostrain and a low magnetic field, at room temperature.

Thanks to the help of intensive modelling, the two first prototypes realised in the framework of the M2 EMS project are functional. It consists of prototypes of single-phase stepper motor whose structure has been transformed from the Lavet motor so as to take into account collective production of the magnet film layers, which are developed in the M2 EMS project.

Onera is participating in all-out research to make helicopters quieter. Objective: noise 8 dB lower than ICAO standards.

This paper presents two approaches for structural damage identification, each based on a different philosophy. The Virtual Distortion Method is a model-updating method of damage assessment, utilizing gradient-based optimization techniques to solve the resulting inverse dynamic problem in the time domain. Case-Based Reasoning is a soft-computing method utilizing wavelet transformation for signal processing and neural networks for training a base of damage cases to use for retrieving a similar relevant case.

Piezoelectric actuators have increased their number of application in adaptronics over the past decade [1]. They can be used with several drive and control strategies and they are more adapted to mechatronics applications requiring bandwidth, accuracy and/or lightweightness. The purpose of this paper is to recall the different existing piezo actuators, the different drive and control techniques and finally review several applications in machine tools, optics.