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    • Adiabatic invariants drive rhythmic human motion in variable gravityPeer reviewedOpen access 

      01 décembre 2020, Boulanger, Nicolas; BUISSERET, Fabien; DIERICK, Frédéric; Dehouck, Victor; White, Olivier, CeREF Technique
      Article scientifique
      Voluntary human movements are stereotyped. When modeled in the framework of classical mechanics they are expected to minimize cost functions that may include energy, a natural candidate from a physiological point of view also. In time-changing environments, however, energy is no longer conserved—regardless of frictional energy dissipation—and it is therefore not the preferred candidate for any cost ...

    • Diffusion in Phase Space as a Tool to Assess Variability of Vertical Centre-of-Mass Motion during Long-Range WalkingPeer reviewedOpen access 

      06 février 2023, Boulanger, Nicolas; BUISSERET, Fabien; Dehouck, Victor; DIERICK, Frédéric; White, Olivier, CeREF SantéCeREF Technique
      Article scientifique
      When a Hamiltonian system undergoes a stochastic, time-dependent anharmonic perturbation, the values of its adiabatic invariants as a function of time follow a distribution whose shape obeys a Fokker–Planck equation. The effective dynamics of the body’s centre-of-mass during human walking is expected to represent such a stochastically perturbed dynamical system. By studying, in phase space, the ...

    • Fine adaptive precision grip control without maximum pinch strength changes after upper limb neurodynamic mobilizationPeer reviewedOpen access 

      30 juin 2021, DIERICK, Frédéric; Brismée, Jean-Michel; White, Olivier; Bouché, Anne-France; Périchon, Céline; Filoni, Nastasia; Barvaux, Vincent; BUISSERET, Fabien, HE Louvain en Hainaut
      Article scientifique
      Before and immediately after passive upper limb neurodynamic mobilizations targeting the median nerve, grip ( GF ) and load ( LF ) forces applied by the thumb, index and major fingers (three-jaw chuck pinch) were collected using a manipulandum during three different grip precision tasks: grip-lifthold- replace (GLHR), vertical oscillations (OSC), and vertical oscillations with up and down ...

    • Higher-derivative harmonic oscillators: stability of classical dynamics and adiabatic invariantsPeer reviewedOpen access 

      06 janvier 2019, Boulanger, Nicolas; BUISSERET, Fabien; DIERICK, Frédéric; White, Olivier, CERISIC
      Article scientifique
      he status of classical stability in higher-deriv- ative systems is still subject to discussions. In this note, we argue that, contrary to general belief, many higher-derivative systems are classically stable. The main tool to see this prop- erty are Nekhoroshev’s estimates relying on the action-angle formulation of classical mechanics. The latter formulation can be reached provided the Hamiltonian ...

    • Motor strategies and adiabatic invariants: The case of rhythmic motion in parabolic flightsPeer reviewedOpen access 

      05 août 2021, White, Olivier; DIERICK, Frédéric; Dehouck, Victor; BUISSERET, Fabien; Boulanger, Nicolas, CeREF Technique
      Article scientifique
      The role of gravity in human motor control is at the same time obvious and difficult to isolate. It can be assessed by performing experiments in variable gravity. We propose that adiabatic invariant theory may be used to reveal nearly conserved quantities in human voluntary rhythmic motion, an individual being seen as a complex time-dependent dynamical system with bounded motion in phase space. ...