Project: New Energy Efficient Piezo Actuation

The stick/slip actuation principle is based on the high dynamics of piezo movements and the different_x000D_friction coefficients during sticking and slipping (stick-slip effect). In some approaches, mass inertia plays an_x000D_important role, leading to the name Inertial Stepping piezo Motors (ISM). Other authors call this principle_x000D_smooth impact drive mechanism (SIDM) [1-2]. The friction force between the moving and the fixed part is_x000D_usually accomplished by the weight of a mass that is moved by a piezoelectric element, which is powered by_x000D_a saw tooth voltage. Alternatively, the friction force can be applied by a spring mechanism. In all cases, the_x000D_piezo extends slowly, allowing the frictional force between the fixed and the moving part to transfer the_x000D_driving forces. In the opposite moving direction, the mass is accelerated very fast so that static friction is_x000D_overridden and the mass moves relatively to the now stagnant moving part. By cycling this sequence, a_x000D_macroscopic movement is realized. By combining the effect in several directions actuators with multiple_x000D_degrees of freedom can be created [3-5]. By exploiting the amplitude increase in resonance, larger velocities_x000D_can be achieved [6-9]. Also, an amplification of the piezo’s stroke can be used to optimise the functionality_x000D_(e.g. [9])._x000D_Among electric linear motors, including piezo motors, the Inertial Stepping piezo Motors (ISM) today are_x000D_considered a promising solution for mechatronic functions in miniature mobile equipment._x000D_One successful industrial example of ISM is the SIDM motor from Sony used in Konica Minolta cameras for_x000D_active stabilisation [1]. ISMs are piezo motors offering a strong potential of miniaturization making them_x000D_suitable not only for cameras but also for medical applications etc. In such small mobile equipment, the_x000D_miniaturization is one key point but the power consumption and lifetime are major issues._x000D_The SPA is a new ISM from CEDRAT. Its present high electromechanical performance (force and speed) in_x000D_regard of its size is deemed promising by experts (GOLDEN MICRON at Micronora 2009 ; INPI RA Innovation price in 2009) especially for embedded applications. Identified markets for SPA motors include biomedical applications, physics & optic instruments, micro-manufacturing equipment, etc (see section 2.3 for details). However to meet the markets, limitations have to be solved:_x000D_- The motor’s overall electromechanical efficiency is poor limiting operation time on battery: Compared to_x000D_other ISM, SPA works with lower electric current when progressing toward more efficiency. However, the_x000D_power conversion from electric to mechanical power in such new motors is complex and has to be_x000D_improved. Recent works indicate ways for efficiency improvement. For example that ISM motors could be_x000D_operated using resonances providing benefits [7-9]. New piezoceramics may also improve efficiency._x000D_- The life time is limited because of wear at the friction interface. This can be improved by comprehensive_x000D_tribology analysis and careful definition of contact interface._x000D_Aim of the proposed project is address these issues and to design and build a new, power-efficient,_x000D_miniature piezoelectric actuator with increased life-time and reasonable manufacturing costs._x000D_References_x000D_[1] Konica Minolta, Piezoelectric supersonic linear actuator, http://www.konicaminolta.com/about/research/_x000D_core_technology/picture/antiblur.html, Zugriff am 22.09.2009._x000D_[2] Morita, T., Yoshida, R., Okamoto, Y., Kurosawa, M. K., Higuchi, T. A Smooth Impact Rotation Motor Using a_x000D_Multi-Layered Torsional Piezoelectric Actuator. IEEE Transactions on Ultrasonics, Ferroelectrics, and_x000D_Frequency Control, 1999, 46 (6): 1439-45._x000D_[3] Howald, L., Rudin, H., Gijntherodt, H.-J. Piezoelectric inertial stepping motor with spherical rotor. Rev. Sci._x000D_Instrum., 1992, 53 (8): 3909-12._x000D_[4] Juhas, L., Vujanic, A., Adamovic, N., Nagy, L., Borovac, B. A Platform for Micropositioning based on Piezo_x000D_Legs. Mechatronics, 2001, 11 869-97._x000D_[5] Zhang, Y., Zhanga, W. J., Hesselbach, J., Kerle, H. Development of a two-degree-of-freedom piezoelectric_x000D_rotary-linear actuator with high driving force and unlimited linear movement. Rev. Sci. Instrum., 2006, 77_x000D_[6] Tuncdemir, S., Ural, S. O., Koc, B., Uchino, K. Rotary/Linear Double-Action Metal Tube Ultrasonic Motor_x000D_With Slanted PZT Ceramic Plates. Proc. of the ACTUATOR, Bremen, Germany, 177-80, 2010._x000D_[7] Koc, B. Piezoelectric Motor, Operated by Exciting Multiple Harmonics of a Square Plate. Proc. of the_x000D_ACTUATOR, Bremen, Germany, 194-7, 2010._x000D_[8] Nishimura, T., Morita, T. Resonant-Type SIDM Actuator. Proc. of the ACTUATOR, Bremen, Germany, 181-5,_x000D_2010._x000D_[9] Belly, C., Claeyssen, F., Le Letty, R., Porchez, T. Benefits from Amplification of Piezo Actuation in Inertial_x000D_Stepping Motors and Application for High-performance Linear Micro Motors. Proc. of the ACTUATOR,_x000D_Bremen, Germany, 198-201, 2010.

Acronym	NEPIA (Reference Number: 6677)
Duration	02/01/2012 - 31/12/2014
Project Topic	Development of new piezoelectric actuator systems for miniature devices with_x000D_ increased power efficiency and longer lifetime
Project Results (after finalisation)	The SPA piezo motor technologies have made progresses in terms of understanding, models, materials, control, reproducibility, noise, reliability. _x000D_These improvements are implemented in CTEC products which increases its attractivity and allows to pass threesholds of interest. _x000D_
Network	Eurostars
Call	Eurostars Cut-Off 6

Project partner

Number	Name	Role	Country
3	CEDRAT Technologies	Coordinator	France
3	Federal Institute for Materials Research and Testing	Partner	Germany
3	Technische Universität Darmstadt, Institut für Elektromechanische Konstruktionen	Partner	Germany