The purpose of this study was to determine viscous properties of human muscle during plantarflexion efforts. Experiments were performed on 17 subjects with an ankle ergometer allowing sinusoidal oscillations during isometric contractions and isokinetic movements. Sinusoidal oscillations led to the expression of (i) Bode diagrams of the musculo-articular system allowing the determination of a da...

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Humans sway. With bipedal stance on a fixed base of support, this sway causes changes in the location of the Center of Pressure as it is projected onto this base of support. Translating the base itself also causes changes in the Center of Pressure. In this study, we have developed a two-dimensional biomechanical model that uses changes in the Anterior-Posterior Center of Pressure (APCOP) to tra...

Ankle-foot orthosis (AFO) designs vary in size, shape, and functional characteristics depending on the desired clinical application. Passive Dynamic (PD) Response ankle-foot orthoses (PD-AFOs) constitute a design that seeks to improve walking ability for persons with various neuromuscular disorders by passively (like a spring) providing variable levels of support during the stance phase of gait...

This paper deals with force and impedance control of series elastic actuators for driving the joints of an exoskeleton for lower limbs. Series elastic actuators are devices where elastic components are introduced between the motor’s output and the load. From the deflection of these components, it is possible to measure the force applied to the load and to control it. Also, the mechanical impeda...

Humans hopping and running on elastic and damped surfaces maintain similar center-of-mass dynamics by adjusting stance leg mechanics. We tested the hypothesis that the leg transitions from acting like an energy-conserving spring on elastic surfaces to a power-producing actuator on damped surfaces during hopping due to changes in ankle mechanics. To test this hypothesis, we collected surface ele...

A monoarticular series elastic actuator (SEA) reduces energetic and peak power requirements compared to a direct drive (DD) in active prosthetic ankle-foot design. Simulation studies have shown that similar advantages are possible for the knee joint. The aims of this paper were to investigate the advantages of a monoarticular SEA-driven hip joint and to quantify the energetic benefit of an SEA-...

This article compares stochastic estimates of multi-variable human ankle mechanical impedance when ankle muscles were fully relaxed, actively generating ankle torque or co-contracting antagonistically. We employed Anklebot, a rehabilitation robot for the ankle, to provide torque perturbations. Muscle activation levels were monitored electromyographically and these EMG signals were displayed to ...

introduction: since most studies on ankle sprain are medical and sports-related and not much epidemiologic and etiologic data from the general population exist in this field, the present study evaluates the relationship between q angle and anthropometric measures with ankle sprain in the general population. methods: in the present case-control study, all of the patients over 18 years age presen...

Two computer-controlled devices for leg rehabilitation are presented: 1) an external knee prosthesis for trans-femoral amputees; and 2) a force-controllable ankle-foot orthosis to assist individuals suffering from drop-foot, a gait pathology resulting from muscle weakness in ankle dorsiflexors. Here muscle-like actuators and biologically-inspired control schemes are employed to enhance patient ...