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Digitale Medien

Time series modeling of neuromuscular system (1984)

Agarwal, Gyan C. ; Goodarzi, Shirin M. ; O'Neill, William D. ; [weitere]

Springer

Biological cybernetics 51 (1984), S. 103-111

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ISSN: 1432-0770

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Informatik , Physik

Notizen: Abstract The dynamic response of the human ankle joint to a bandlimited random torque perturbation superimposed on a constant bias torque is observed in normal human subjects. The applied torque input, the joint angular rotation output, and the electromyographic activity using surface electrodes from the extensor and the flexor muscles of the ankle joint were recorded. Transfer function models using time series techniques were developed for the torque — angular rotation input-output pair and for the angular rotation — electromyographic activity input-output pair. A parameter constraining technique was applied to develop more reliable models. It is shown that the asymptotic behavior of the system must be taken into account during parameter optimization to develop better predictive models.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00357923

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2

Digitale Medien

Analysis of kinematic invariances of multijoint reaching movement (1995)

Goodman, Simon R. ; Gottlieb, Gerald L.

Springer

Biological cybernetics 73 (1995), S. 311-322

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ISSN: 1432-0770

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Informatik , Physik

Notizen: Abstract. There is a no unique relationship between the trajectory of the hand, represented in cartesian or extrinsic space, and its trajectory in joint angle or intrinsic space in the general condition of joint redundancy. The goal of this work is to analyze the relation between planning the trajectory of a multijoint movement in these two coordinate systems. We show that the cartesian trajectory can be planned based on the task parameters (target coordinates, etc.) prior to and independently of angular trajectories. Angular time profiles are calculated from the cartesian trajectory to serve as a basis for muscle control commands. A unified differential equation that allows planning trajectories in cartesian and angular spaces simultaneously is proposed. Due to joint redundancy, each cartesian trajectory corresponds to a family of angular trajectories which can account for the substantial variability of the latter. A set of strategies for multijoint motor control following from this model is considered; one of them coincides with the frog wiping reflex model and resolves the kinematic inverse problem without inversion. The model trajectories exhibit certain properties observed in human multijoint reaching movements such as movement equifinality, straight end-point paths, bell-shaped tangential velocity profiles, speed-sensitive and speed-insensitive movement strategies, peculiarities of the response to double-step targets, and variations of angular trajectory without variations of the limb end-point trajectory in cartesian space. In humans, those properties are almost independent of limb configuration, target location, movement duration, and load. In the model, these properties are invariant to an affine transform of cartesian space. This implies that these properties are not a special goal of the motor control system but emerge from movement kinematics that reflect limb geometry, dynamics, and elementary principles of motor control used in planning. All the results are given analytically and, in order to compare the model with experimental results, by computer simulations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004220050187

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3

Digitale Medien

Kinematic description of variability of fast movements: analytical and experimental approaches (1993)

Gutman, Simon R. ; Latash, Mark L. ; Almeida, Gil L. ; [weitere]

Springer

Biological cybernetics 69 (1993), S. 485-492

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ISSN: 1432-0770

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Informatik , Physik

Notizen: Abstract Analysis of variability of fast aimed movements predicts the properties of trajectory variance. The analysis is based on a kinematic model with nonlinear changes in “internal time”. The purpose of the work was to identify different sources of variability and their influence on the trajectory variance. An analytical expression for the speed-accuracy trade-off is introduced. Experiments were performed with subjects making single-joint elbow flexion movements over different distances as fast as possible with their eyes closed to memorized targets. Standard deviation of movement trajectory increased during the first part of the movement and subsequently decreased. The variance peaked after the time of peak velocity, close to the time of peak deceleration. A dependence of the trajectory variance on movement distance (speed-accuracy trade-off) was seen during the movement (at times of peak velocity and peak deceleration) but not after the movement termination. We conclude that the previously reported drop in the variability of movement trajectory during the deceleration phase does not necessarily mean a compensation by the control system but may result from purely kinematic properties of the movement. The importance of the time of measurement for analysis of the speed-accuracy trade-offs is emphasized.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01185420

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4

Digitale Medien

Kinematic description of variability of fast movements: analytical and experimental approaches (1993)

Gutman, Simon R. ; Latash, Mark L. ; Almeida, Gil L. ; [weitere]

Springer

Biological cybernetics 69 (1993), S. 485-492

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ISSN: 1432-0770

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Informatik , Physik

Notizen: Abstract Analysis of variability of fast aimed movements predicts the properties of trajectory variance. The analysis is based on a kinematic model with nonlinear changes in “internal time”. The purpose of the work was to identify different sources of variability and their influence on the trajectory variance. An analytical expression for the speed-accuracy trade-off is introduced. Experiments were performed with subjects making single-joint elbow flexion movements over different distances as fast as possible with their eyes closed to memorized targets. Standard deviation of movement trajectory increased during the first part of the movement and subsequently decreased. The variance peaked after the time of peak velocity, close to the time of peak deceleration. A dependence of the trajectory variance on movement distance (speed-accuracy trade-off) was seen during the movement (at times of peak velocity and peak deceleration) but not after the movement termination. We conclude that the previously reported drop in the variability of movement trajectory during the deceleration phase does not necessarily mean a compensation by the control system but may result from purely kinematic properties of the movement. The importance of the time of measurement for analysis of the speed-accuracy trade-offs is emphasized.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00199448

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5

Digitale Medien

Analysis of kinematic invariances of multijoint reaching movement (1995)

Goodman, Simon R. ; Gottlieb, Gerald L.

Springer

Biological cybernetics 73 (1995), S. 311-322

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Details

ISSN: 1432-0770

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Informatik , Physik

Notizen: Abstract There is a no unique relationship between the trajectory of the hand, represented in cartesian or extrinsic space, and its trajectory in joint angle or intrinsic space in the general condition of joint redundancy. The goal of this work is to analyze the relation between planning the trajectory of a multijoint movement in these two coordinate systems. We show that the cartesian trajectory can be planned based on the task parameters (target coordinates, etc.) prior to and independently of angular trajectories. Angular time profiles are calculated from the cartesian trajectory to serve as a basis for muscle control commands. A unified differential equation that allows planning trajectories in cartesian and angular spaces simultaneously is proposed. Due to joint redundancy, each cartesian trajectory corresponds to a family of angular trajectories which can account for the substantial variability of the latter. A set of strategies for multijoint motor control following from this model is considered; one of them coincides with the frog wiping reflex model and resolves the kinematic inverse problem without inversion. The model trajectories exhibit certain properties observed in human multijoint reaching movements such as movement equifinality, straight end-point paths, bell-shaped tangential velocity profiles, speed-sensitive and speed-insensitive movement strategies, peculiarities of the response to double-step targets, and variations of angular trajectory without variations of the limb end-point trajectory in cartesian space. In humans, those properties are almost independent of limb configuration, target location, movement duration, and load. In the model, these properties are invariant to an affine transform of cartesian space. This implies that these properties are not a special goal of the motor control system but emerge from movement kinematics that reflect limb geometry, dynamics, and elementary principles of motor control used in planning. All the results are given analytically and, in order to compare the model with experimental results, by computer simulations.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00199467

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6

Digitale Medien

“Adequate control theory” for human single-joint elbow flexion on two tasks (1995)

Gottlieb, Gerald L. ; Chen, Chi-Hung ; Corcos, Daniel M.

Springer

Annals of biomedical engineering 23 (1995), S. 388-398

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ISSN: 1573-9686

Schlagwort(e): Human motor control ; Force planning ; EMG patterns

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin , Technik allgemein

Notizen: Abstract The control of distance and speed during single-joint human elbow flexion is accomplished by different modes of activating the motoneuron pools. Distance is controlled by modulating the duration of activation, while speed is controlled by modulating the intensity. The experiments reported on here compare movements of different distances under two sets of instructions: subjects moved either as fast and accurately as possible or in a specified time. The first task showed duration modulation, whereas the second, which required simultaneous control of distance and speed, showed both duration and intensity modulation. These results are interpreted in the context of a model for motor control, predicated on the existence of movement plants that use prior knowledge of the dynamics of the movement task to generate muscle activation patterns that produce joint torques. These plans use a simple algorithm based upon parameters of the task such as distance, load, and speed. From this plan, the kinematic trajectory emerges.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00000006

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