High-Stroke Motion Modelling and Voltage/Frequency Proportional Control of a Stick-Slip Microsystem

International audienceA new control type for stick-slip microsystems is proposed in this paper : the voltage/frequency (U/f) proportional control. It gives a best resolution relatively to the classical control algorithm. It is also an englobalization of three classical controllers : the sign controller, the classical proportional controller and the frequency proportional controller. A high stroke model of a stick-slip microsystem is first given. Then, we theoretically analyse the performances of the closed loop process with the U/f controller. Finally, we give some experimental results obtained with different values of the proportional gains

Development, modelling and control of a micro/nano positioning 2DoF stick-slip device.

International audienceThe works presented in this article are motivated by the high performances required in micromanipulation/ microassembly tasks. For that, this paper presents the developement, the modelling and the control of a 2 degrees of freedom (in linear and angular motion) micropositioning device. Based on the stick-slip motion principle, the device is characterized by unlimited strokes and submicrometric resolutions. First, experiments were carried out to characterize the performances of the micropositioning device in resolution and in speed. After that, a state-space model was developed for the sub-step functioning. Such functioning is interesting for a highly accurate task like nanopositioning. The model is validated experimentally. Finally, a controller was designed and applied to the micropositioning device. The results show good robustness margins and a response time of the closed-loop system

Voltage/frequency proportional control of stick-slip micropositioning systems.

International audienceA new control type for stick-slip micropositioning system is proposed in this paper : the voltage/frequency (U/f) proportional control. It gives more precise results relatively to the classical control algorithm. It is also an assembly of two classical controllers : the sign and the classical proportional controllers. A high stroke model of a stick-slip micropositioning system is first given. Then, we will theoretically analyse the performances of the closed loop process with the U/f controller. Finally, we will give some experimental results obtained with different values of the proportional gains

Maximum Effectiveness of Electrostatic Energy Harvesters When Coupled to Interface Circuits

Accepted versio

Review on the Modeling of Electrostatic MEMS

Electrostatic-driven microelectromechanical systems devices, in most cases, consist of couplings of such energy domains as electromechanics, optical electricity, thermoelectricity, and electromagnetism. Their nonlinear working state makes their analysis complex and complicated. This article introduces the physical model of pull-in voltage, dynamic characteristic analysis, air damping effect, reliability, numerical modeling method, and application of electrostatic-driven MEMS devices

Workshop on "Robotic assembly of 3D MEMS".

Proceedings of a workshop proposed in IEEE IROS'2007.The increase of MEMS' functionalities often requires the integration of various technologies used for mechanical, optical and electronic subsystems in order to achieve a unique system. These different technologies have usually process incompatibilities and the whole microsystem can not be obtained monolithically and then requires microassembly steps. Microassembly of MEMS based on micrometric components is one of the most promising approaches to achieve high-performance MEMS. Moreover, microassembly also permits to develop suitable MEMS packaging as well as 3D components although microfabrication technologies are usually able to create 2D and "2.5D" components. The study of microassembly methods is consequently a high stake for MEMS technologies growth. Two approaches are currently developped for microassembly: self-assembly and robotic microassembly. In the first one, the assembly is highly parallel but the efficiency and the flexibility still stay low. The robotic approach has the potential to reach precise and reliable assembly with high flexibility. The proposed workshop focuses on this second approach and will take a bearing of the corresponding microrobotic issues. Beyond the microfabrication technologies, performing MEMS microassembly requires, micromanipulation strategies, microworld dynamics and attachment technologies. The design and the fabrication of the microrobot end-effectors as well as the assembled micro-parts require the use of microfabrication technologies. Moreover new micromanipulation strategies are necessary to handle and position micro-parts with sufficiently high accuracy during assembly. The dynamic behaviour of micrometric objects has also to be studied and controlled. Finally, after positioning the micro-part, attachment technologies are necessary

Micro injection moulding: tooling and process factors

The development of new micro devices is highly dependent on manufacturing systems that can reliably and economically produce micro components in large quantities. Micro injection moulding is one of the key technologies for micro-manufacture and is considered as a cost effective replication method for mass production. The capabilities of this replication technology have to be studied systematically in order to determine the process constraints. The present work concerns the tooling and process factors that influence micro injection moulding. The requirements of this manufacturing process are identified, and a review of the current state of the art in the field, Chapter 2, is used to assess the potential of this technology. To analyse further the manufacturing capabilities of this technology against the requirements, an investigation of the pre-filling, filling and part removal stages of the process cycle is conducted. In particular, in Chapter 3 the pre-filling capabilities of multi cavity micro tools with the use of a runner system is explored. The filling performance of spiral-like micro cavities was studied as a function of runner size in combination with selected process factors. Then, in Chapter 4 the filling of micro mould cavities with controlled tool surface finishes is investigated. Factors affecting the flow behaviour are discussed and a special attention is paid to the interaction between the melt flow and the tool surface roughness. Using the same part design as that of the tool surface finish investigation, in Chapter 5 a Finite Element Analysis (FEA) is used to verify the effects of process parameters, particularly the factors affecting shear rate, pressure and temperature. The results of this investigation were then compared with those reported in the experimental study. Finally, in Chapter 6 the application of micro mould surface treatments is analysed. The effects of different surface treatments on the de-moulding of parts with micro features are investigated to identify the best processing conditions in regards to de-moulding behaviour. To validate the process effects for these three process stages micro injection moulding experimental set-ups were specially designed and implemented. These experiments apply various part designs, tool-making techniques, process factors, part inspection and condition monitoring techniques, and FEA. To further understand the importance of process characteristics at the micro scale, an in depth analysis of the experimental results for each of the selected investigations was carried out. Finally, in Chapter 7 the results from each of the investigations are summarised, and the main research findings identified, in particular the influence of runner size on the process performance, tool surface finish effects on the filling process, the accuracy and sensitivity of the proposed FEA model, and the effects of tool surface treatment on part de-moulding