2 State of the Art Previous studies indicated that introducing adaptable compliance to dynamic walking is beneficial to modulating walking performance and extending the versatility [1-3]. However, in most of these studies, the stiffness is changed off-line. The transition of different walking patterns in real time was not investigated. Our previous study [4] has demonstrated walking pattern tra...

We tested an innovative method to estimate joint stiffness and damping during multijoint unfettered arm movements. The technique employs impulsive perturbations and a time-frequency analysis to estimate the arm's mechanical properties along a reaching trajectory. Each single impulsive perturbation provides a continuous estimation on a single-reach basis, making our method ideal to investigate m...

This work deals with effects of asymmetric stiffness on the dynamic behaviour of the rotor system. The analysis is presented through an extended Lagrangian Hamiltonian mechanics on the asymmetric rotor system, where symmetries are broken in terms of the rotor stiffness. The complete dynamics of asymmetries of rotor system is investigated with a case study. In this work, a mathematical model is ...

BACKGROUND Ankle-foot orthoses (AFOs) are commonly prescribed during rehabilitation after limb salvage. AFO stiffness is selected to help mitigate gait deficiencies. A new custom dynamic AFO, the Intrepid Dynamic Exoskeletal Orthosis (IDEO), is available to injured service members but prescription guidelines are limited. QUESTIONS/PURPOSES In this study we ask (1) does dynamic AFO stiffness a...

One of the most important factors influencing the track maintenance is the transitions between parts of the track with different vertical stiffness. The dynamic...

Due to the limited control bandwidth of pneumatic artificial muscles, joint stiffness characteristics and their effects on safety and performance of human-friendly robots should be considered in the frequency domain. This paper introduces the concept of effective dynamic stiffness and validates its model with the Stanford Safety Robot. Experimental results show that the dynamic stiffness demons...

Recent work in the field of robotics optimal control has focused on designing and employing variable impedance actuators. Such actuators provide a high dynamic range and fast response. Until now, impedance modulation has been restricted to physical stiffness alone, while its other components, such as damping, are set to a fixed value. In this work the influence of introducing variable damping i...

Combining several materials (“phases”) into a composite material permits creation of new materials with tunable overall response, e.g., elastic properties, which can be related to the elastic moduli, arrangement, and concentrations of the composite’s phases. A recent advance predicts use of one phase having correctly tuned non-positive-definite elastic moduli (i.e., negative stiffness) in a two...

seismic base isolation are devices that used to limit the human and material damage caused by an earthquake. this devices diffuse the energy induced at the time of the earthquake before being transferred to the structure.the base isolated structures when subjected to the near-fault eathquakes which contain long-period velocity pulses that may coincide with the period of base isolated structures...

This paper is an overview of quasistatic measurement technique used to determine mechanical properties of sound absorbing materials. Experimental context and behaviour of polymer foam and rock wool are summarized. Concerning parameters are: static and dynamic strains, dynamic effects such as skeleton resonance and coupling with saturating fluid. Material anisotropy and frequency dependance of c...