On Internal Modeling of the Upright Postural Control in Elderly

Abstract

The second most common cause of injury in the elderly population is falling. In an effort to understand the mechanism behind the reduced ability to maintain balance in any posture or activity, we study the performance of the central nervous system as a controller of the body, while maintaining the balance in some postures or activities. Towards this direction, forty-five subjects aged over 70 were tested in different trials of quiet stance: a) hard stable surface with open eyes, b) stable surface with closed eyes, c) soft unstable surface with open eyes, and d) unstable surface, while eyes were closed. In the sequel, the body kinematics were described by legs and trunk segment angles in the sagittal plane, while the muscle activations were described by a weighted sum of rectified EMG signals from tibialis anterior and gastrocnemius muscles of left and right legs. Using the neuro-science hypothesis and adaptive control theory, a completely novel model was identified for the CNS based on the feedback internal model. The proposed model is able to predict the output commands, based on a recurrent neural network, while the efficiency of the proposed scheme has been proven based on multiple experimental results, showing that the model can sufficiently predict the muscle activity based on the optimum sensory inputs.

Feasibility of Sensor Technology for Balance Assessment in Home Rehabilitation Settings

“…Despite this, force plate-based systems are highly unlikely to be utilized in home-based rehabilitation due to installation, cost and space related issues. Camera-based motion capture systems (i.e., Vicon) were utilized in three of the reviewed studies [ 22 , 25 , 36 ]. It was observed that camera-based systems are as impractical for a home-based rehabilitation setting as the force plate systems.…”

“…From the 23 reviewed papers, research was categorised into three key main purposes: (1) Understanding the underlying biological/anatomical functional causes creating disturbances in balance [ 24 , 32 , 34 , 36 ]; (2) identifying the falls or diagnosing balance issues [ 20 , 26 , 27 , 28 , 30 , 33 , 38 , 39 , 41 , 42 ]; and (3) identifying the factors (external or internal to a person) in order to predict when falls will happen [ 21 , 22 , 29 , 31 , 35 ].…”

“…The first category focuses on understanding if the biological/anatomical problems which create a disturbance in balance can be identified by sensors in some way. The articles in this category focus on assessing cognitive impairment linked to walking speed variation and walking trajectories [ 32 ], muscle fatigue [ 34 ], or indicators of functioning of the Central Nervous System (CNS) [ 36 ] or autonomous nervous system [ 24 ]. In order to achieve the goal of evaluating underlying biological/anatomical problems, the sensors used by the reviewed works (e.g., EMG) required complex setup and mounting at very specific body locations by an expert.…”

Stabilization of an Inverted Pendulum via Human Brain Inspired Controller Design

“…However, to the best of our knowledge, there are few articles that have studied the controller of balance robotic applications based on human data. In [18], [19] we proposed a novel conceptual scheme for the modeling of the CNS in an upright posture that has been verified by human data and can be used as a controller of an inverted pendulum as the main model for most of the balance robotic applications. As an extension, in this work, we experimentally evaluate the proposed scheme with the following additional contributions.…”

Comparison of Trunk and Leg Sway During Single Leg Stance

“…One of musculoskeletal involvements for balance could be how different body segments participate in the adjustment in response to the body balance. It has been revealed that with multisensory feedbacks to the central nervous system (CNS) and sensorimotor control of CNS, leg and trunk segments could coordinate to maintain balance in different directions [4], angular excursions [5], and postures and activities [5,6]. During the time, body segments might response differently.…”