https://luck.synhera.be/handle/123456789/109 2026-04-23T09:02:33Z 2026-04-23T09:02:33Z White, Olivier BUISSERET, Fabien DIERICK, Frédéric Boulanger, Nicolas https://luck.synhera.be/handle/123456789/3086 2025-11-26T09:34:21Z 2025-11-25T00:00:00Z

From brain to motion: harnessing higher-derivative mechanics for neural control White, Olivier; BUISSERET, Fabien; DIERICK, Frédéric; Boulanger, Nicolas Optimal Feedback Control provides a theoretical framework for goal-directed movements, where the nervous system adjusts actions based on sensory feedback. This theory assumes that there exists a cost function that is optimized throughout one's movement. It is natural to assume that mechanical quantities should be involved in cost functions, but this does not imply that the mechanical principles that govern human voluntary movements are necessarily Newtonian. We argue that integrating principles from Lagrangian and Hamiltonian higher-derivative mechanics, i.e. dynamical models relying on a Lagrangian of the form $L\left(\vec x,\dot{\vec x},\ddot{\vec x},\dots,\vec x^{\, (N)}\right)$, with $N\geq 2$ and where $\vec x^{\, (i)}$ denotes the $i^{\rm th}$ time-derivative of the position $\vec x$, provides a more natural framework to study the constraints hidden in human voluntary movement within Optimal Feedback Control theory.

2025-11-25T00:00:00Z Buisseret, Fabien Sanso, Aline Sen, Eda nur White, Olivier Boulanger, Nicolas Dierick, Frédéric https://luck.synhera.be/handle/123456789/3084 2025-11-26T09:33:33Z 2025-09-25T00:00:00Z

Stress on the stride: How treadmill walking reveals gait variability differences in children, young adults, and seniors? Buisseret, Fabien; Sanso, Aline; Sen, Eda nur; White, Olivier; Boulanger, Nicolas; Dierick, Frédéric The assessment of gait variability is a valuable approach for characterizing an individual’s walking pattern over extended time scales. Variability parameters, such as the coefficient of variation, the Hurst exponent, and the Minkowski fractal dimension of the attractor, are influenced by factors like age, dual-task performance, and neurodegenerative conditions. Treadmill walking, a compact and widely used method, enables precise data collection when combined with measurement devices. However, differences between treadmill and overground variability raise questions about its applicability to real-life gait analysis. This study investigates how treadmill walking, as an external stressor, reveals gait variability differences among children, young adults, and seniors by analyzing the center of mass trajectory. Fifteen children (median age: 11 years), 24 young adults (median age: 22.5 years), and 16 seniors (median age: 60 years) participated. Variability was assessed using stride intervals and phase-space metrics. Results indicate that young adults demonstrate “optimal” gait variability, characterized by minimal coefficients of variation and maximal fractal dimension. In contrast, children and seniors exhibit less predictable and less complex gait patterns, with differences in Hurst exponents distinguishing these groups. These findings highlight the nontrivial integration of age, fear of falling, and neurological maturation in gait variability. Practical implications for rehabilitation and clinical assessments are discussed, underscoring the need for protocol standardization and cautious interpretation of treadmill-based variability data.

2025-09-25T00:00:00Z Fouchard, Romain BUISSERET, Fabien https://luck.synhera.be/handle/123456789/3081 2025-11-26T09:33:08Z 2025-09-01T00:00:00Z

Combien de temps mettrait Usain Bolt au 100 m sur la Lune ? Fouchard, Romain; BUISSERET, Fabien Question de Roland Ghelardi, Miramas (13) : Combien de temps mettrait Usain Bolt au 100 m sur la Lune ? Des calculs de biomécanique permettent de fournir une réponse précise.

2025-09-01T00:00:00Z Brihaye, Yves Buisseret, Fabien Hartmann, Betti Layfield, Oliver https://luck.synhera.be/handle/123456789/3041 2025-04-09T07:58:24Z 2025-04-08T00:00:00Z

Boson stars and black holes with complex and real scalar hair Brihaye, Yves; Buisseret, Fabien; Hartmann, Betti; Layfield, Oliver We discuss boson stars and black holes with scalar hair in a model where the complex scalar field forming the boson star and the hair on the black hole, respectively, interacts with a real scalar field via a H´enon-Heiles-type potential. We demonstrate that black holes and boson stars carrying only a real scalar field with cubic self-interaction are possible and that black holes with both real and complex scalar field branch off from these solutions for sufficiently large interaction between the two fields and/or sufficiently large horizon radius rh. The latter possess lower mass for the same choice of coupling constants than the former, however seem to be thermodynamically preferred only for high enough temperature.

2025-04-08T00:00:00Z