Issues that are central to the modeling and analysis of a human movement system include (1) musculotendon dynamics, (2) the kinetics and kinemat- ics of the biomechanical system, and (3) the relationship between neurolog- ical control and the formulation of the system as an open or closed loop pro- cess. This paper will address these problems in the context of two particular movement systems. The flrst to be addressed is the human ocular system. Eye movement systems are ideal for studying human control of movement since they are of relatively low dimension and easier to control than other neuromuscular systems. By scrutinizing the trajectories of eye movements it is possible to infer the efiects of motoneuronal activity, deduce the central nervous system's control strategy, and systematically observe the efiects of perturbations in the controls. An application of the locomotory-control sys- tem will also be presented in this paper. In particular, a model of human gait is developed for the purpose of relating neural controls to the state of stress in a skeletal member. This is achieved by modeling the human body as an ensemble of articulating rigid-body segments controlled by a minimal muscle set. Neurological signals act as the input into the musculotendon dynamics and from the resulting muscular forces, the joint moments and resulting motion of the segmental model are derived. At flxed moments in the gait cycle, the joint torques and joint reaction forces are incorporated into an equilibrium analysis of the segmental elements, modeled as elastic bodies undergoing biaxial bending. Both movement systems that are dis- cussed here emphasize a forward or direct dynamic approach that results in a natural ∞ow of neural-to-muscular-to-movement events while utilizing physiologically realistic models of the musculotendon actuators that faith- fully reproduce trajectories and muscle tension.
The oculomotor system is composed of six extraocular muscles attached to the orbit and to the eyeball, of extraocular motor neurons located in three different brainstem motor nuclei, and of premotor centres and circuits involved in the generation and control of the different types of eye movement. Its precise functional design and robust biomechanics have allowed this motor system to survive almost unchanged across the different trends in vertebrate evolution.
A model for the human eye-movement mechanism is derived. The derivation is based on a literature search directed toward identifying
and mathematically describing each component through physiological and anatomical considerations. It is felt that although
certain parameter values may not be exactly correct (for the data were taken from a wide variety of animals), we can place
a great deal of confidence in the configuration.
The quantitative analysis of the smooth pursuit eye movements in a patient who had a left hemispherectomy 11 years previously showed that although the remaining right hemisphere could generate normal pursuit to the right, leftward pursuit was always slower than the target velocity and required corrective saccades. The number of saccades was greatest at lower target speeds and decreased at higher target speeds but the average amplitude of saccades increased monotonically with target velocity. The proportion of the pursuit attempt accomplished by saccades was always about 80%, and the velocity gain of the pursuit system was 0.24 to 0.34.
In this article we investigate the problem of how to model and control the combined motion of the human head and eye. We develop a model of the muscles, based on a simplified physical model and an assumption that the muscles can be modeled as damped springs with a second order linear dynamics. We then find control laws that both make the combined pupil-movement follow a given trajectory, and make the separate head and eye trajectories three times continuously derivable. Our controls also make the energy produced in the movement small, since we believe that to be a reasonable, physical control-criterion. 1 INTRODUCTION The purpose of this article is two-folded, and the first question, discussed in Section 2, concerns finding a mathematical model of the combined, horizontally rotational movements of the human head and eye. Therefore we first develop simplified physical models of the muscular configurations in the neck and the eye respectively. Then these physical models are translated i...
Models of mechanics of eye moveinmis CRC Pre-^s McM-hanical components of human eye movements^/ohx/ij
Robinson D A Robinson
A B Meara
Robinson D. A. Models of mechanics of eye moveinmis. CRC Pre-^s. 1981. [.3] Robinson D. A., D. M. O'Meara. A. B. Scott, and Ce)llins C. C. McM-hanical components of human eye movements. Journal of Applied Phi/.^/ohx/ij. 26(5):548 553, 1969.
A 2d dynamic- model of human eye movement. Master's the^sis. Texas Tech Unive-rsitv
A. McSpadden. A 2d dynamic- model of human eye movement. Master's the^sis. Texas Tech Unive-rsitv. Lubbock. Texas. V.VJS.
A feedback control analysis of the neuro-musculo-skeletal hindlimb PhD Dissertation University of Maryland, 1988. sijsfem of a cat 25 r A. V. Hill. The heat of shortening and dynamic ce)iistants of musele
J. He. A feedback control analysis of the neuro-musculo-skeletal hindlimb. PhD Dissertation. University of Maryland, 1988. sijsfem of a cat 25 r A. V. Hill. The heat of shortening and dynamic ce)iistants of musele. Five. Roy. Soc. Lond.,. (B126):136-195, 1938.