Linear actuators
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Cryogenic piezo characterisation and integration For Fine Steering Tip/Tilt Mechanism
19 June 2023
High precision cryogenic applications are demanding domains that require precise knowledge of component performance. In the case of active components such as piezoelectric actuators, such knowledge includes stroke, capacitance and Coefficient of Thermal Expansion (CTE). These parameters are difficult to define with precision because of the combination of small displacements and low temperature sensor compatibilities. A high stability and low sensibility test bench is required to obtain such results
Super amplified piezo actuator
19 June 2023
MICROMEGA DYNAMICS is a spin-off company of the “Université Libre de Bruxelles” (ULB), Department of Mechanical Engineering and robotics of Pr PREUMONT. This department created in 1989, is specialized in the modeling and control of mechatronic systems and in the active control of vibrations.
Frequency Dependence of Mouse Brain Tissue Stiffness Measured in vivo with MR Elastography
19 June 2023
Magnetic resonance elastography (MRE) is a non-invasive imaging technique for quantitative measurement of the mechanical properties of biologic tissue in vivo [1]. The clinical interest in MRE has largely been driven by the direct relationship between tissue health and stiffness. As a result, MRE may provide significant clinical value for the non-invasive diagnosis of pathology and response to therapy by tracking tumor development and monitoring therapeutic response. MRE may also have considerable value in the development of treatment protocols in pre-clinical, rodent models of cancer. Because of cost and versatility, the mouse, in particular, is widely employed in oncologic studies. To resolve its small anatomic features, MRE experiments in mice must be performed with high driving frequencies (>600 Hz). However, high-frequency waves exhibit increased attenuation, reducing wave penetration depth and making it more difficult to impart motion deep into tissue with sufficient amplitude to overcome background noise. Also, biologic tissue is viscoelastic; hence, its response to load depends on the driving frequency. Recent MRE studies in mouse brain have been performed in high-field scanners (7 – 11.7T) at single driving frequencies of 1000 and 1200 Hz [2,3]. Here, we perform elastography in mouse brain tissue at 4.7T and report viscoelastic material properties over a range of driving frequencies (600 – 1800 Hz).
Design of a 2 stages compressor for mobility applications, using compact and efficient Moving Iron Controllable Actuators
19 June 2023
An actuator is rescaled for integration into a compressor used for the liquefaction of hydrogen vapor boil off, into a propellant storage system. The goal is to evaluate the feasibility of liquid hydrogen zero boil off, for long duration storage at 20 Kelvin cryogenic liquid condition. This article presents the actuator trade off, selection and special features imposed by the application. The actuator design is presented, its characteristics are measured, and resulting performances are presented and discussed.
FSPA and BSMA Nanometric positioning actuators for ground and space applications
19 June 2023
Many applications and more specifically space projects show need for a stable sub-micrometre positioning actuator. In order to meet this need, Cedrat Technologies has designed the new FSPA brand. This linear stepping actuator offers sub-micrometric positioning resolution along 5mm stroke combined with high actuation force (>100N) and the ability to hold its position without power.
The IASI-NG instrument is one of the key payload on-board METOP-SG which is a new meteorological satellite for Europe. The instrument is based on a Mertz interferometer and requires a very precise positioning of an optical blade used to separate the interferometer’s branches. A dedicated version of the FSPA, the Beam Splitter Mechanisms Actuator (BSMA) is then developed to achieve this nanometric positioning which is a key parameter for the overall instrument performance.
This paper firsts present the internals of both FSPA and BSMA actuators. Major design differences and their respective impact on the resulting performances are detailed. Results from the acceptance and qualification test campaigns are also presented.
Design of a dynamic tribometer applied to piezo inertia drive motors
7 November 2019
In Inertia Drive Motors, generated motion is based on stick-slip principle. Current analytical models are predictive enough to calculate qualitatively their optimal performances, such as maximal step size and speed, with relatively few input parameters. Butn they do not take into account the contact life and temporal evolution of parameters as friction factor all along lifetime of IDM. So analytical models reach their limitswhen precise predictions are necessary.
