Cedrat Technologies, innovation in mechatronics

In the frame of the Cleansky 2 projects SYNJET3C and FLOCOS, CEDRAT TECHNOLOGIES (CTEC) and TRISITEC are collaborating with both FRAUNHOFER and ONERA institutes, two major European research leaders in the development of Synthetic Jet Actuators (SJA) for Aerospace applications. While SYNJET3C project is dedicated to SJA mechanical designs and optimisation, as well as testing including wind tunnel tests, FLOCOS project is dedicated to the design and manufacturing of a specific SJA drive Electronic called SADS (Synthetic Jet Actuator Drive System).

In many cases piezoelectric actuators reach limitations in terms of maximum displacement and cycling frequency. Most amplified actuator technologies struggle to go over the millimeter of stroke. Furthermore certain closed-loop applications demand stroke measurement integrated into the actuator. While few amplifiers on the market can offer 20Amps current over a few 100ms, development of high power supply units runs parallel with actuator improvements. However with the introduction of high power supplies comes the problem of self-heating of the piezo ceramic. Finally extreme environmental conditions in terms of harsh conditions and high temperatures need to be addressed in order to open these markets for piezo actuators. Cedrat Technologies has been heavily investigating in solutions to overcome all of these drawbacks and these solutions are presented here.

The piloting of APA's composite shell by SA75D power amplifier offers new opportunities for dynamic new applications. Two in particular were received and are being studied: the design of a compact table tensile micro machine for characterizing stress-strain laws at high strain rate of wires, fibers, strands and textile samples that will usefully complete the fleet of dynamic testing machines available, the generation of synthetic jets of air pulsed also studied at ONERA. The energy capacity (displacement, force) without or with an external linear load were modeled versus the rise time using the Simulink code and experimentally measured using a very light device. Other identified improvements remain to be implemented both at the APA's actuators as the Amplifier SA75D to get some gains.

Future matrix sensors will acquire an area on ground and are then susceptible to image shift due to satellite movement during acquisition. Design, Build and Test a breadboard mechanism that could shift telescope line of sight and freeze observed area during image acquisition.

The objective of the European Cleansky project is to develop new technologies for future aircraft enabling a 20-30% fuel burn reduction and related CO2 emissions and a similar reduction in noise levels compared to current aircraft. One of the ways to reach this goal is to improve the aerodynamic performances of current high lift devices. Active flow control is unanimously seen as the best mean to reach this objective. By suppressing flow separation and/or delaying stall, active flow control will increase wing aerodynamic performances. The partnership between CTEC and ONERA in the framework of the VIPER project has led to the design, manufacturing and test of an innovative pulsed jet actuator based on a CTEC amplified piezo-actuator (APA). Its aim is to provide a pulsed sonic jet up to 500Hz with a mass flow around 34 g/s through a slot 1mm wide and 80mm long. Coupled with CTEC SA75D switching power amplifier this actuator produces the expected sonic jet with an electrical consumption around 40W thanks to energy recovery. The results of the actuator characterisation (mechanical, fluidic) are presented in this paper.

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.

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.