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Control of magnetic actuators in electric contactors by current shapping
19 June 2023
Most of present electric contactors use magnetic actuators of reluctant type (so called electromagnets) that are supplied with a simple voltage source. The use of a reluctant actuator in this condition leads to a considerable force increase when the magnetic circuit is closing, which creates damaging rebounds of the electrical contacts. To have a better control of the closing dynamics, we develop an electric drive method to reduce impact speed and to improve the closing dynamics. In this method, the reluctant actuator structure is unchanged. The appropriate current shape to be injected into the actuator is determined using a calculation method.
An improved accurate Beam Steering piezoelectric Mechanism for ATlid instrument
19 June 2023
A new tip tilt mechanism based on low voltage piezoelectric actuators has been designed by Cedrat Technologies to answer the high level of stability required for the Earthcare satellite. The Beam Steering Assembly aims to deviate a pulsed high energy UV laser beam to compensate for misalignment between the emission and reception paths of ATLID [1] with a very high stability and resolution. In this paper, the authors points out the BSM development with the main mechanism design issues including performances, mechanical and thermal stability; low power consumption; high integration level; high reliability and safety; cleanliness requirements and give the results of the qualification campaign done at Cedrat Technologies’ to establish the final functional performances in preparation of the Flight Models deliveries for the BSM.
Analysis of Needle–Tissue Friction during Vibration-Assisted Needle Insertion
19 June 2023
In this paper, a vibration-assisted needle insertion technique has been proposed in order to reduce needle–tissue friction. The LuGre friction model was employed as a basis for the current study and the model was extended and analyzed to include the impact of high-frequency vibration on translational friction. Experiments were conducted to evaluate the role of insertion speed as well as vibration frequency on frictional effects. In the experiments conducted, an 18 GA brachytherapy needle was vibrated and inserted into an ex-vivo soft tissue sample using a pair of amplified piezoelectric actuators. Analysis demonstrates that the translational friction can be reduced by introducing a vibratory low-amplitude motion onto a regular insertion profile, which is usually performed at a constant rate.
ATLID Beam Steering Mechanism and derived new piezoelectric based devices for optical applications
19 June 2023
In Space & Defence (as well as in many others fields), there is a trend for miniaturisation in active optics requiring new actuators. Applications also often require the ability to withstand high vibrations and shocks levels, as well as vacuum
compatibility for space applications. A new generation of small and smart actuators such as piezoelectric (piezo) actuators, are resolving this trend, thanks to their capacity to offer high energy density and to support both extreme and various requirements. This paper first presents the BSM mechanism and its requirements, the technologies involved in
the design and the validation campaign results. Secondly, a derived XY piezoelectric positioning stage based on the same APA® and associated Strain Gage sensing technology is presented with its associated performances. Finally, a new piezoelectric motor based on the APA® technology, which allows the combination of long stroke while maintaining high
resolution positioning of optical elements, is presented with experimental performances.
ATLID BSA Beam steering assembly piezo tip tilt
19 June 2023
ATLID (ATmospheric LIDar) is one of the four instruments of EarthCARE satellite, it shall determine vertical profiles of cloud and aerosol physical parameters such as altitude, optical depth, backscatter ratio and depolarisation ratio. The BSA (Beam Steering Assembly), included in emission path, aims at deviating a pulsed high energy UV laser beam to compensate the pointing misalignment between the emission and reception paths of ATLID [1]. It requires a very high stability and high resolution.
Beam steering mechanism for earthcare atmospherice Lidar Instrument: an improved piezo tip-tilt mechanism
19 June 2023
In the context of the ATLID instrument [1] embedded in the EarthCARE mission (Earth Cloud, Aerosol and Radiation Explorer), a Beam Steering Assembly is deviating a pulsed high energy UV laser beam to compensate the pointing misalignment between the emission and reception paths of ATLID with a very high stability and high resolution. Within the EarthCARE mission, led by ESA, Astrium is responsible for the ATLID instrument. The BSA development, manufacture and tests were assigned by Astrium to Sodern, an EADS filial.
