Yvan Michellod

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A double-stage feedback control structure for a double-stage mechanical system, with a single optical metrology is developed to reach nanometer accuracy at high bandwidth over large displacements. A piezoelectric stack actuator is used for fine positioning, while a permanent magnet (PM) stepper motor handles the coarse positioning. Two different control(More)
A new dynamical model of the shoulder has been developed. It consisted of eleven muscles. The glenohumeral joint is modeled as a spherical joint, allowing for three rotations. Muscle wrapping around a spherical humeral head is calculated analytically. The problem of indeterminated muscle forces is solved in two steps. First, an intermediate solution is(More)
To improve the resolution of the very large telescope interferometer (VLTI) a two-stage mechanical system, a so called differential delay line (DDL), is developed jointly by the EPFL and the Observatory of Geneva. The system is designed to reach nanometer accuracy at high bandwidth over large displacements. The coarse stage features a permanent magnet (PM)(More)
The goal of the present work was assess the feasibility of using a pseudo-inverse and null-space optimization approach in the modeling of the shoulder biomechanics. The method was applied to a simplified musculoskeletal shoulder model. The mechanical system consisted in the arm, and the external forces were the arm weight, 6 scapulo-humeral muscles and the(More)
The consequence of the loss of involutivity of a specific set of vector fields on the periodicity of the joint motion is examined for redundant robots. An output task, defined as a one dimensional periodic closed curve embedded in a two dimensional working surface, is realized through the computation of joint velocities in the configuration space. Depending(More)
Deriving unambiguously the orbital parameters and masses of extrasolar planets requires at least 2-dimensional information on either the positions or motions of the planet directly (currently out of reach) or, indirectly, of the host star. The latter can be done with high-precision astrometry at the 10 microarcsec level. To achieve this goal, a consortium(More)
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