Kick and Catch - cooperative microactuators for freely moving platforms

Jade Welt: Jade Hochschule entwickelt mikrotechnische Systeme weiter (German) 

Moving masses are important components of microsystems and are usually supported by solid springs. These serve as joints in order to overcome the lack of ball bearings in microtechnology. However, they limit the working range. To hold a mass in a deflected position, the actuator must therefore always be active or locked. This consumes a lot of energy.

The aim of this research project is to develop new types of microactuators that are not supported by beam structures but move freely. In addition, they should save energy, offer longer travel distances and be faster. To make this possible, different types of actuators must cooperate with each other. To enable high speeds and large deflections, the mass will be subjected to a sudden impact (kick) and enter a free-flight phase. This mass is then caught in a defined final position (catch).


Project Groups:

Ulrike Wallrabe

University of Freiburg

Department of Microsystems Engineering, Laboratory for Microactuators

Georges-Köhler-Allee 102

79110 Freiburg

Martin Hoffmann

Ruhr-Universität Bochum

Chair for Microsystems Technology

Universitätsstraße 150

44801 Bochum

Christoph Ament

University of Augsburg

Chair for Control Engineering

Eichleitner Straße 30

86159 Augsburg

Tamara Bechtold

Jade University of Applied Sciences

Department of Engineering, Modeling and Simulation of Mechatronic Systems

Friedrich-Paffrath-Straße 101

26389 Wilhelmshaven


Where people work on "Kick and Catch": Wilhelmshaven, Bochum, Augsburg, Freiburg (from nord to south)


Tamara Bechtold's group for modelling and simulation of mechatronic systems at the Jade University aims to develop novel methods for creating system-level models of the kick and catch microactuator system. This work precedes the activities of the Ament group, since an actuator model is needed for the controller design. Furthermore, both the Hoffmann and Wallrabe groups benefit from this work, since an efficient and accurate model simplifies the development of their respective actuators. The methods developed in this work can be applied to a large class of cooperative, multistable microactuator systems. 

The system-level Kick and Catch actuator model will integrate two sub models, the electromagnetic Catch actuator model and the electrostatic respectively piezoelectric Kick actuator model. The micro actuators considered here include nonlinear structural dynamics (with periodic contacts between sphere and platform), electrostatic and magnetic fields for actuation and position sensing. To model these effects with sufficient accuracy, multiphysical numerical models are necessary. Sub models are highly accurate, but too large to be employed within a control loop. Furthermore, the strongly varying duration of the kick, spin, fly and catch periods, impose extremely high requirements on modelling the contact events in an adequate way. Thus it is the task of the Bechtold group to develop suitable methods for order reduction of multiphysical field-solution models and supply those to the Ament group for integration in the control loop. Beyond the present microactuators systems, those methods will be applicable to other multiphysical models, especially under the presence of time-varying contacts and nonlinear effects.

Observer-based control-scheme of the Kick and Catch actuator integrating a system-level model, which consists of a reduced order model (ROM), a lumped element (LE) model or a look-up table (LT) derived from finite element models. The system-level model describes the actuator's behavior in response to voltage and current excitation; in response it provides flying mass' and platform positions. The model supports controller development.


The people behind Kick and Catch at the kick-off meeting in October 2019 in Karlsruhe: Prof. Dr.-Ing. Ulrike Wallrabe, Arwed Schütz, Prof. Dr.-Ing. Tamara Bechtold, Michael Olbrich, Prof. Dr.-Ing. Christoph Ament, Prof. Dr.-Ing. Martin Hoffmann, Peter Conrad
Working principle of Kick and Catch actuator: The kick module applies a sudden push and "launches" the hemisphere. A system of permanent and electromagnets controls the flight. Finally, the catch actuator carefully decelerates the hemisphere in order to land it.
Sectional three-dimensional view of the catch actuator with labeled components.