Human position monitoring based on external referent body configuration

Gil L?cio Almeida
Universidade de Ribeir?o Preto, Brazil

Simon Goodman
Department of Kinesiology, PSU,University Park PA 16802,USA

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     Last modified: May 13, 2007

Abstract
We propose to develop an intelligent system for measuring and capturing the configuration of the human body. Initial proposed use of the system is in physical therapy applications, where it is important that a patient maintain correct sitting/standing posture. The functioning of the system reflects the principle of referent body configuration [1] organized by nervous system in spatial coordinates. The medicinal effect of the system is based on the assumption that physical therapist can define some optimal coordinates of referent configuration conforming to the individual parameters and state of the subject. Additional applications of the underlying technology include motion tracking, gaming, advanced human-computer interaction, as well as collision avoidance, robotics and other industrial uses, where position of an object or a group of objects needs to be tracked in real time.
The system continuously monitors the patient?s posture and reports the collected data to a central location for analysis and processing. A set of sensors is located on selected points on arms, feet, and torso. Each sensor contains an ultra-sound transmitter (piezoelectric ceramic resonator) and an acoustic receiver (detector). High reliability of the device is provided by roll-call algorithm of inter-sensor communication, and cross-correlation technique for calculating the distances between their positions. The distances are fed to algorithm of 3-dimensional scaling calculating sensor coordinates in Cartesian space. These coordinates are compared with the referent configuration assigned by the physical therapist. The therapist can evaluate the posture and give instructions for improvement, make decisions about patient?s response to treatment, etc. In the autonomous feedback mode, the system presents an acoustic (or visual) signal about the difference between the ?external? referent and actual configurations. This short posture correction message helps the subject to return to the ?correct? position. The process of correcting the body position can be considered simultaneous multi-directional reaching to several targets opening a wide spectrum of experimental setups. The principle of referent body configuration utilizes the indices of the minimum of EMGs [2] for additional estimation of the body configuration, more individualized and detailed than the sensors positions.
References:
1. Feldman AG, Levin MF, 1995, Beh Brain Sci.18:723-806
2. Feldman et al, 1998, J Electromyogr Kinesiol. 8:383-90