Tomas Menard

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We consider the problem of estimating the time-varying stiffness in real-time of a Variable Stiffness Actuator in an agonistic-antagonistic configuration. The estimation of the stiffness is done in two steps. First, we use operational calculus which provides a relation between the positions/velocities of the motors and the link, the torques of the motors(More)
A continuous–discrete time observer is proposed for a class of uncertain nonlinear systemswhere the output is available only at non uniformly spaced sampling instants. The underlying correction term depends on the output observation error and is updated in a mixed continuous-discrete fashion. The proposed observer is first introduced under a set of(More)
This paper presents a continuous-discrete time observer for a class of uncertain nonlinear systems with non uniformly sampled measurements. Two features of the proposed observer are worth to be pointed out. The first one consists in the simplicity of its calibration, while the second one lies in its comprehensive convergence analysis. More specifically, it(More)
In this paper, one aims at addressing the adaptive observer design for a class of multivariable nonlinear systems with Lipschitz nonlinearities. Two adaptive observers have been derived using two different approaches issued from an overview of the available adaptive observer design literature. The first one is a natural extension of a recently proposed(More)
Safe Physical Human Robot Interaction, conservation of energy and adaptability are just the main robotic applications that prompted the development of a number of Variable Stiffness Actuators (VSA). Implemented in a variety of ways, they use various technologies, and feature the most diverse mechanical solutions, all of which share a fundamentally(More)