Cedrat Technologies, innovation in mechatronics

Modular Stepping Piezo Actuators (MSPA) use the stick-slip principle to combine high resolution positioning (<μm) with long stroke (>cm). These motors provide unlimited motion in both rotation and translation. Fine mode allows precise positioning (<10nm). Since it is a module, it easily fits any existing devices requiring up to 25N of driving force with a speed up to 50mm/s. This motor module benefits the use of space qualified Amplified Piezo Actuators (APA®). It is then deemed a good candidate for severe environments such as vacuum, cryo, vibrations, nonmagnetic etc… This paper presents three technical challenges encountered for the development of MSPA product. The first one is the issue of noise resulting from stick-slip actuation below ultrasonic frequencies. The second is the miniaturization at low voltage: One is macro size (sugar cube) working at 45V is characterized, the other is micro size (grain of rice) powered at low voltage below 60V. The third challenge is the successful and reliable integration of the module within new customer applications and new Cedrat Technologies’ products.

In the framework of a French National Program, the project ASPIC aims at using synthetic jet actuators to improve aerodynamic performance of aircrafts. The partnership between Cedrat Technologies (CTEC) and the French Aerospace Lab (ONERA) in this project has led to design, manufacture and test a high efficiency innovative synthetic jet actuator. This device relying in part on an ONERA patent is actuated by a CTEC amplified piezoactuator (APA). Its aim is to provide a high speed synthetic jet compatible with flow control application on aircrafts or any other vehicle. Latest available test results and experimental performances of the ASPIC synthetic actuator are presented in this document: in particular, a peak exit velocity of 135m.s-1 during suction, and of 150m.s-1 during blowing, with an optimal actuation frequency bandwidth between 200 and 300Hz.

Amplified Piezo Actuators (APA®) from CEDRAT TECHNOLOGIES are known to be compact and especially performing in dynamic applications. The recent evolutions realized on the APA® and drive electronics allow them to address active damping better than magnetic proof mass in terms of the Force to Volume ratio above some 10Hz. The dynamic capability of the APA® has been improved thanks to preload method enhancement. Research has successfully shown the possibility to achieve a high dynamic force level similar to the static blocked force of the piezo actuator. This technical progress coupled with an amplified motion makes possible the generation of high mechanical proof mass load at relatively low frequency. It produces a force higher than 100N in a volume of Ø40x75mm within a range of [100-300Hz]. This paper presents relevant uses of APA® for active damping in machining applications. Several machining case studies are reported integrating Amplified Piezo Actuators within the spindle head, inside the cutting tool or beside the workpiece clamp.

A project called RPA (Rotor à Pales Actives) was launched three years ago to study the possible benefits of implementing active trailing edge flaps on a helicopter main rotor. The main objectives of this project are to decrease BVI noise in descent flight and improve the dynamic behavior of the rotor throughout the largest possible flight domain. After a first phase dedicated to the design of the best flap configuration at scale 1, the second phase of the project deals with the design of a wind-tunnel scale model of a rotor equipped with active flaps. An off-the-shelf piezo-electric actuator is used together with a specific patented flap-driving mechanism. Such an active device was tested under centrifugal loads as well as under aerodynamic loads in order to prepare future wind-tunnel tests. The results obtained under centrifugal loads allowed to clear the active device but the aerodynamic testing showed that some improvements were needed. Corresponding modifications are under way to fully clear the active device to be used on a complete rotor model.

Bolted connection is the most common way to assemble mechanism. It is widely used in transport domains, such as aerospace, rail, aircrafts… Ensuring that the minimum torque value is always present in the assembly is one of the main maintenance tasks for those components. A possible way to carry out those actions is to implement active component in the bolted assembly. A solution is proposed in this document. Construction, potentialities, performances (based on lap-joint demonstrator) and limitations are identified and confronted to other techniques.

The objective of this paper is to provide results of an experimental and analytical investigation of Amplified Piezoelectric Actuators (APA) as vibrational isolator in a configuration of a mechanical Single Degree of Freedom system. The investigation is aimed at assessment of the mechanical properties modification ability via shunting techniques. The investigation consist of a phenomenological modelling of the APAs considered as generators and experimental verification of the vibrational energy dissipation ability in frequency domain. The results obtained during this investigation reveal that it is feasible to receive more than 20 dB reduction of the displacement amplification in the resonant range. Moreover, three tested examples of APA reveal up to 9 % of resonant frequency shift due to proper adjustment of the electronic shunting circuit, which is an encouragement for further analyses towards application of the APAs in semi-passive vibration control applications.

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.