System and methodology for analysing, evaluating and correcting human biped locomotion.

Schor, Vladimir ; Sindila, Gheorghe ; Popescu, Diana 等

1. INTRODUCTION

There is a worldwide interest for a deeper understanding of a very complex process such us human gait, which implies a synchronization of the skeletal, neurological and muscular systems of the body. This interest especially regards the clinical assessment of pathological gait and rehabilitation of people who, for a different medical reason (stroke, amputation, neurological impairment, muscle disease, etc.), suffered a modification of the normal walking pattern. Human gait analysis constitutes a research subject for both medicine doctors (for diagnosis and rehabilitation, prosthesis design) and engineers (for developing new methods of visually investigating human movements, mathematical modeling of human gait and implementing the gait pattern in robots, human gait recognition, etc.).

The first researches in the field date from 1975 when Mann summarized in a chart the kinematics interactions that occur during the gait cycle, and made the distinction between stance and swing phases. The work continued over the years with studies regarding the dynamic of human gait, biomechanics of walking and running, movement tracking and recognition, study regarding the locomotion models and the brain activity during the foot movements, study regarding the reflexes involved in muscles activity during walking, balance and control of walking, etc.

In Romania, the researches have been conducted in different hospitals and research centers (Orthopedic Department of St. Pantelimon Hospital--Bucharest, University Politehnica of Timisoara--BioArt CEEX Project, Recovery Department of University of Medicine and Pharmacology Carol Davila--Bucharest, etc.) especially for and diagnosis and movement corrections.

2. METHODS FOR GAIT ANALYSIS

Due to the large number of persons having walking problems and due to an increasing interest of the health and insurance companies in a faster diagnosis and rehabilitation, independent centers for study the human gait have been founded for the study of all the processes involved in this natural and complex activity--walking. In this context, there are laboratories focused on using markers for studying different anatomical segments involved in locomotion (Gavrila, 1999). The inconvenient of such an approach resides in the small number of steps considered and the difficulty of experimentally studying the dynamic of gait.

Another type of kinematical analysis is goniometry, which even if it gives the possibility to study a bigger number of steps (walking cycles), does not offer information regarding the dynamical aspects. The dynamic analysis depends of forces measuring platforms on three directions, or baropodometers which principal disadvantage is the small number of recorded steps not enough for evaluating the human subject movement stereotype.

Other methods, more complex, combine in different manners the above-mentioned methods, adding also biological investigations (electromyography, electroencephalography) needed for evaluating the human gait control mechanisms.

The study of the literature in the field showed that the devices used in the gait analysis labs and the correspondent methods of assessment, are limited when it comes to evaluate the movement stereotype of a human being, due to the small number of cycles, which can be used to record the gait dynamic.

In the last couple of year, the research focused also on modeling and simulating human locomotion, in order to have a global and integrated view on dynamical and kinematical aspects. However, not even this approach can not properly describe the human gait stereotype due to its complexity and to the fact that each simplification leads to modified and irrelevant results. (Cappozzo, 1984), (Ackermann& Schiehlen, 2006), (Kale et al., 2002).

Devices such us Electronic Baropodometer, Body Analysis Kapture, Biomechanics, etc, are mostly used in diagnosis, not considering the movement pattern and thus not offering the possibility to vary in a controlled manner the conditions in which the gait is taking place. Moreover, these devices do not have the capability to correct the gait stereotype. In this context, another device called Ergocontrol was developed by S.C. Medisport S.R.L., a Romanian company headquartered in Bucharest. This device is using a new approach in evaluating, correcting and optimizing human biped locomotion, by measuring in real time all the parameters contributing to propulsion of the center of mass of a human subject.

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3. ERGOCONTROL--SYSTEM FOR EVALUATING, CORRECTING AND OPTIMIZING HUMAN GAIT

Ergocontrol device (fig.1-2) offers the capability of characterizing the human gait stereotype, and then to correct and optimize it in order to increase the physical performances of sportsmen or to restore the normal walking ability of those who suffered different trauma.

As mentioned before, all the parameters involved in human locomotion are measured in real time and the results are represented as curves describing the dependency between the force of propulsion and the position of different elements of the human locomotor chain (fig.3). This information is directly linked to prioreceptive information coming from the specialized anatomical elements from muscles, tendons and articulations used in the natural subcortical gait control.

Another novelty introduce by Ergocontrol is that the graphical representation allows the patient to correct the movement pattern in real time, attempting to follow the shape of the curves presented on the screen.

An electromechanical system and a force transducer are used for collecting the information regarding the force of propulsion, and sent to specialized software for a real time analysis and evaluation. The basic scheme of the device is presented in figure 4.

The electrodynamical break FE and the electrical motors ME1 and ME2 allow controlling the conditions in which the movement is taking place, by varying the load depending on the diagnosis and the methodology used for correcting the gait pattern. Motors ME1 and ME2 have digital signal processors, position transducers (which allow a precise position evaluation both in relative ad absolute movement), and analog digital converters for force measurement. The information referring to the force of propulsion developed by the human subject S are collected by a computer assisted electromechanical system and its corresponding force and position transducers, and then are used as input in an evaluation software. The results are presented in real time as curves on the screen M, both to the patient and the medical assistant for correcting the movement pattern. The use of visual feedback constitutes the interface between the subcortial movement control and the voluntary movement control.

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4. CONCLUSION

Ergocontrol device described in this paper represents a new electromechanical system which can be used for human gait diagnosis and correction. The functioning of the device is based on a new approach, which consists in real time measurement of parameters involved in the gait and controlling the parameters characterizing the external conditions in which the gait is taking place (initial speed, moving forward friction coefficient, etc.).

Moreover, the approach combines the classical methods used in gait analysis (digital image analysis, goniometry and podometry) with the capabilities of the device to record a large number of gait cycles for properly characterizing the movement stereotype and to use corrective working models.

Further research will focus on improving the electromechanical subsystem of the device and implementing new corrective working models for movements of arms.

5. REFERENCES

Ackermann, M., Schiehlen, W. (2006), Dynamic Analysis of Human Gait Disorder and Metabolical Cost Estimation, Archive of Applied Mechanics, Volume 75, Numbers 10-12/October

Cappozzo, A. (1984), Gait Analysis Methodology, Hum Movt Sc 1984; 3: 27-50

Gavrila, D.M. (1999), The Visual Analysis of Human Movement: A survey, Computer Vision and Image Understanding, vol.73, no.1, January, pp.82-98

Kale, A., et al., (2002), Gait analysis for human identification, Proceedings of 3rd International Conference on Audio and Video Based Person Authentication, June 2003, ttp://citeseer.ist.psu.edu/kale03gait.html

Mann, R.A. (1975), Biomechanics of the foot, American Academy of Orthopaedic Surgeons (Ed.) Atlas of orthotics: Biomechanical principles and application, pp. 257-266, St. Louis: C.V. Mosby

Schor, V. (1983), A multifunctional Modular Ergometer for Simulating the Specific Dynamics in Swimming, International series on sport science, vol.14, Biomechanics and Medicine in Swimming, Human Kinetics Publisher Inc.