The overall mechanical properties of a joint are generated by a combination intrinsic (mechanical) and reflex (neural) mechanisms. Nevertheless, many methods for estimating joint mechanical properties have used a linear dynamic model whose …
The mechanical properties of a joint are determined by the combination of intrinsic and reflex mechanisms. However, in some situations the reflex contributions are small so that intrinsic mechanisms play the dominant role in the control of posture …
Dynamic joint stiffness determines the relation between joint position and torque, and plays a vital role in the control of posture and movement. Dynamic joint stiffness can be quantified during quasi-stationary conditions using disturbance …
This paper introduces an iterative algorithm for the identification of time-varying (TV)-Hammerstein systems. This system is composed by a TV static nonlinearity followed by a TV Box-Jenkins linear model. The algorithm uses two basis function …
The Hammerstein system provides a good model for the stretch reflex contribution to joint stiffness under quasi-stationary conditions. However, the model parameters change dramatically with the operating point defined by the joint angular position …
Joint stiffness has been extensively used to study joint biomechanics. It can be described by a block-oriented, nonlinear, parallel-cascade structure under quasi-stationary conditions defined by the joint operating point. The model parameters are …
Dynamic joint stiffness defines the torque generated at the joint in response to position perturbations. Dynamic stiffness is modulated by the angular position and the muscle activation level, making it difficult to estimate during large movements …
Generation of torque around a joint usually involves the activation of several agonist muscles and may also involve the co-activation of antagonist muscles. Therefore, a valid model for the dynamic relation between surface EMG (an indirect measured …
Noise characteristics play an important role in evaluating tools developed to study biomedical systems. Despite usual assumptions, noise in biomedical systems is often nonwhite or non-Gaussian. In this paper, we present a method to analyze the noise …