title: A new measure for upright stability.
abstract: The control of balance is a primary objective in most human movements. In many cases, research or practice, it is essential to quantitatively know how good the balance is at a body posture or at every moment during a task. In this paper we suggest a new measure for postural upright stability which assigns a value to a body state based on the probability of avoiding a fall initiation from that state. The balance recovery problem is solved for a population sample using a strength database, and the probability of successfully maintaining the balance is found over the population and called the probability of recovery (PoR). It, therefore, describes an attribute of a body state: how possible the control of balance is, or how safe being at that state is. We also show the PoR calculated for a 3-link body model for all states on a plane, compare it to that found using a 2-link model, and compare it to a conventional metric: the margin of stability (MoS). It is shown, for example, that MoS may be very low at a state from which most of the people will be able to easily control their balance.
authors: Department of Mechanical and Environmental Informatics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, 152-8552 Tokyo, Japan. Electronic address: hadi@nagoya.riken.jp.
authors: Mohammad Hadi
authors: MH
authors: Honarvar
authors: Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, 152-8552 Tokyo, Japan. Electronic address: motomu@mech.titech.ac.jp.
authors: Motomu
authors: M
authors: Nakashima
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D009068:Movement; D004856:Postural Balance; D011187:Posture; D011336:Probability; D020127:Recovery of Function / Q000502:physiology
keywords: Balance; Body state; Perturbation; Postural upright stability