Cedrat Technologies, innovation in mechatronics

The MICATM linear actuator family (Moving Iron Controllable Actuator) is being continuously improved at CEDRAT TECHNOLOGIES (CTEC) for applications needing high controllable stroke, force, and power. The MICA300CM is a new actuator model, having improved configuration based on cylindrical shape. A first version based on plain bearing offers up to 12mm stroke and 300N continuous force with a weigh of only 3kg. A second version is based on new frictionless flexure bearings. The former one is especially designed to achieve zero maintenance over several years of operation, with high efficiency, infinite resolution, and high controllability performance. This version of the MICA300CM has been derived to offer a proof mass configuration, for vibrationcancellation applications on machining processes. A latest version is also currently under design, and prototyping, specifically for reciprocating power piston applications, such as compressors, pressure wave generators, and pumps. Its high efficiency, ultra-long lifetime capability, and compactness, makes it perfectly suitable for embedded thermal machines based on Stirling, Joules Thomson, and Rankin Thermodynamic cycles. This paper presents this 4 design concepts, their test results and perspective for applications.

Air Liquide advanced Technologies in collaboration with Cedrat Technologies and SMAC has performed a study of a compact vibration control platform for mechanical cryocoolers. This solution has been proposed as an alternative approach to cryocooler integration with respect to suspended systems that must be mechanically locked during the launch phase. This system allows significant reduction of the platform’s physical size and mass.

Tuned mass dampers are simple and efficient devices for suppression of machine tool chatter, which is one of the principal effects limiting productivity in many machining processes. However, their effectiveness depends on a proper tuning of the damper dynamics to the dynamics of the machine. This involves the dynamic characterisation of the machining process, in order to identify the critical resonance frequency, and the possibility of matching the resonance frequency of the damper to frequency. The difficulty of meeting these two requirements has been limiting the use of tuned mass dampers in industrial applications.

Two typical characteristics of direct piezoelectric actuators are displacements of ten micrometers and high stiffnesses. recently, multilayers actuators have been improved, and they now display strains of approximately 1200ppm at low excitation levels (less than two hundred volts). Thus, they are well suited to perform precise positioning of optical devices. But for industrial needs, this performances is still insufficient for positioning devices with larger displacements (in the range of several hundred micrometers).

MRF actuators are new electromechanical components using Magneto Rheological Fluids (MRF). When submitted to a high enough magnetics fiels, MRF switch from a liquid to a near solid body.

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.

There is a strong demand of controllable actuators for both traditional and new applications. A controllable actuator should be able to accelerate, break, inverse the motion of the load, all along the stroke. It means the force produced by the actuator should be proportional (at least roughly) to the applied electric excitation, and in particular, the sign of the actuation force could be changed all along the stroke.