Marteau (outil) | EPFL Graph Search

1- Angrois 2- Œil 3- Table 4- Panne 5- MancheSchéma d'un marteau.png Un marteau est un outil percuteur, servant par exemple à aplatir un morceau de fer ou à enfoncer un clou. Le marteau est fait d'une tête et d'un manche. La tête est constituée d'une masse métallique et agit par inertie, augmentée par la longueur du manche et par celle du bras du manipulateur. Un bon marteau est conçu pour que la prise en main corresponde au centre de percussion. Lorsque la tête est faite d'une matière peu dure comme le bois ou la résine, on parle de maillet, et lorsqu'il a au moins une face tranchante on parle de hache. Le marteau est utilisé dans de nombreuses professions, comme celles de forgeron ou de maçon. Pour le charpentier, il a été en grande partie remplacé par le pistolet à clous. Il est l'instrument privilégié, l'outil essentiel du dinandier, du chaudronnier, du prospecteur ou encore du géologue, qui en manipulent de toutes sortes pour différents usages. Il date, comme le couteau, de

A Vibrational Technique for in vitro Intraoperative Prosthesis Fixation Monitoring

Kamiar Aminian, Hooman Dejnabadi, Seyed Abdolmajid Yousefsani

Objective: In this paper, a new vibrational modal analysis technique was developed for intraoperative cementless prosthesis fixation evaluation upon hammering. Methods: An artificial bone (Sawbones)-prosthesis system was excited by sweeping of a sine signal over a wide frequency range. The exponential sine sweep technique was implemented to the response signal in order to determine the linear impulse response. Recursive Fourier transform enhancement (RFTE) technique was applied to the linear impulse response signal in order to enhance the frequency spectrum with sharp and distinguishable peak values indicating distinct high natural frequencies of the system (ranging from 15 kHz to 90 kHz). The experiment was repeated with 5 Sawbones-prosthesis samples. Upon successive hammering during the prosthesis insertion, variation of each natural frequency was traced. Results: Compared to classical Fast Fourier Transform, RFTE provided a better tracing and enhancement of frequency components during insertion. Three different types of frequency evolving trends (monotonically increasing, insensitive, and plateau-like) were observed for all samples, as confirmed by a new finite element simulation of the prosthesis dynamic insertion. Two main mechanical phenomena (i.e., geometrical compaction and compressive stress) were shown to govern these trends in opposite ways. Follow-up of the plateau-like trend upon hammering showed that the frequency shift is a good indicator of fixation. Conclusion: Alongside the individual follow-up of frequency shifts, combinatorial frequency analysis provides new objective information on the mechanical stability of Sawbone-prosthesis fixation. Significance: The proposed vibrational technique based on RTFE can provide the surgeon with a new assistive diagnostic technique during the surgery by indicating when the bone-prosthesis fixation is acceptable, and beyond of which further hammering should be done cautiously to avoid bone fracture.

2020

Hammering Does Not Fit Fitts' Law

Auke Ijspeert, Tadej Petric, Cole Stewart Simpson

While movement is essential to human wellbeing, we are still unable to reproduce the deftness and robustness of human movement in automatons or completely restore function to individuals with many types of motor impairment. To better understand how the human nervous system plans and controls movements, neuromechanists employ simple tasks such as upper extremity reaches and isometric force tasks. However, these simple tasks rarely consider impacts and may not capture aspects of motor control that arise from real-world complexity. Here we compared existing models of motor control with the results of a periodic targeted impact task extended from Bernstein's seminal work: hammering a nail into wood. We recorded impact forces and kinematics from 10 subjects hammering at different frequencies and with hammers with different physical properties (mass and face area). We found few statistical differences in most measures between different types of hammer, demonstrating human robustness to minor changes in dynamics. Because human motor control is thought to obey optimality principles, we also developed a feedforward optimal simulation with a neuromechanically inspired cost function that reproduces the experimental data. However, Fitts' Law, which relates movement time to distance traveled and target size, did not match our experimental data. We therefore propose a new model in which the distance moved is a logarithmic function of the time to move that yields better results (R-2 >= 0.99 compared to R-2 >= 0.88). These results support the argument that humans control movement in an optimal way, but suggest that Fitts' Law may not generalize to periodic impact tasks.

Frontiers Research Foundation2017

A Vibrational Technique for in vitro Intraoperative Prosthesis Fixation Monitoring

Kamiar Aminian, Hooman Dejnabadi, Seyed Abdolmajid Yousefsani

2020