Kanty Rabenorosoa

Precise Motion Control of a Piezoelectric Microgripper for Microspectrometer Assembly

The Fourier Transform (FTIR) microspectrometer discussed in this paper is an example of a complex Micro-Opto-Electro-Mechanical System (MOEMS) configured as an optical bench on a chip. It is an important benchmark application for microtechnology due to increased demands for the use of miniature wavelength detection instruments in bio, nano and material science. This device can be manufactured using automated microassembly and precision alignment of hybrid silicon and glass components, and in particular, of a micro-beamsplitter cube along 3 rotational degrees of freedom. In this paper, a piezoelectric microgripper with four degrees of freedom was attached to a precision robot in order to enhance its dexterity and align the beamsplitter to arcsecond angular tolerance. The modeling and control of the microgripper, and the alignment algorithm utilizing a novel spot-Jacobian servoing technique are discussed. Experimental results obtained during joint on-going work in Texas and in France are presented, demonstrating the advantage of using the microgripper for optical alignment of the microspectrometer.Copyright

Scanning Micromirror Platform Based on MEMS Technology for Medical Application

This topical review discusses recent development and trends on scanning micromirrors for biomedical applications. This also includes a biomedical micro robot for precise manipulations in a limited volume. The characteristics of medical scanning micromirror are explained in general with the fundamental of microelectromechanical systems (MEMS) for fabrication processes. Along with the explanations of mechanism and design, the principle of actuation are provided for general readers. In this review, several testing methodology and examples are described based on many types of actuators, such as, electrothermal actuators, electrostatic actuators, electromagnetic actuators, pneumatic actuators, and shape memory alloy. Moreover, this review provides description of the key fabrication processes and common materials in order to be a basic guideline for selecting micro-actuators. With recent developments on scanning micromirrors, performances of biomedical application are enhanced for higher resolution, high accuracy, and high dexterity. With further developments on integrations and control schemes, MEMS-based scanning micromirrors would be able to achieve a better performance for medical applications due to small size, ease in microfabrication, mass production, high scanning speed, low power consumption, mechanical stable, and integration compatibility.

Kinematic Modeling of an EAP Actuated Continuum Robot for Active Micro-endoscopy

An active micro-endoscope based on concentric tubes, an emerging class of continuum robots, is presented hereby. It is designed to reach the digestive tube and the stomach for early cancer detection and intervention. The manipulator is constructed from three flexible, telescopic, and actuated tubes. The actuators are based on Electro-Active Polymer electrodes coated and patterned around the tube. A full multi-section kinematic model is developed; it is used to compare the existing constant curvature configuration to the proposed micro-endoscope. That comparison is established according to the reachable workspace and the performance indices. The results are used to prove the effectiveness of the embedded actuation method to reach the workspace more dexterously, which is very useful in medical systems, especially in surgical applications.

Experimental Characterization of Drobot: Towards Closed-Loop Control

This paper presents advances in the development of a microrobotic platform actuated by three liquid droplets in a gaseous environment (Drop-bot or Drobot). Drobot builds on the bubble robotics concept earlier introduced by Lenders [1]. A new platform design is described allowing three actuated degrees of freedom : one translational (vertical) and two rotational (tilt). The platform-supporting droplets are generated by pushing liquid out of a tank through linear actuators. Preliminary kinematic (output/input ratio), static (compliance) and dynamic (response time and evaporation time) characterizations of Drobot are reported, as well as promising experiments with an ionic liquid, whose negligible volatility is suitable for vacuum or hot environments. Additionally, a method to deduce the platform attitude from the measurement of the electrical resistance of the droplets is discussed. This work contributes toward the automatic control of the platform, which will be fully addressed in a following publication.

Guiding Strategies for the Assembly of Micro-Components Subjected to Planar Pull-Off Force

During micro-assembly processes, planar contacts often appear (between two manipulated components, one manipulated component and its gripping tool or substrate). Adhesion forces being predominant at the microscale, such contacts have important consequences on assembly strategies. One of these adhesion forces is the pull-off force which is the necessary force to break a contact. This article focuses on the measurement of pull-off force of micrometric planar contacts (50×50 μm2 ) and shows that it can be in the range of several hundreds of microNewtons. Consequences of this pull-off force on assembly strategy, especially guiding tasks, are then introduced. A strategy based on a force study is applied on teleoperated assembly sequences and validates the proposed guiding strategy. The study also enables to establish design rules that are specific for the microscale and that can be applied to the field of MOEMS assembly.Copyright

An Origami-Based Tunable Helmholtz Resonator for Noise Control: Introduction of the Concept and Preliminary Results

A Helmholtz resonator is a passive acoustic device that enables noise reduction at a given frequency. This frequency is directly related to the volume of the resonator and to the size of the neck that couples the resonator to the acoustic domain. In other words, controlling the volume of the cavity allows a real time tunability of the device, which means noise control at any desired frequency. To that end, we propose an Origami-based tunable Helmholtz resonator. The design is inspired from the well-known origami base, waterbomb. Such foldable structures offer a wide range of volume shifting which corresponds to a frequency shifting in the application of interest. The foldability of the structure is first investigated. Then, a series of numerical simulations and experimental tests were preformed are presented, in order to explore the capabilities of this origami structures in acoustic control. A shift in the frequency domain of up to 197 Hz (131–328 Hz) was achieved in an experimental testing using 3D printed rigid devices.Copyright