A significant problem in motor control is how
information about movement error is used to modify control
signals to achieve desired performance. A potential
source of movement error and one that is readily controllable
experimentally relates to limb dynamics and associated
movement-dependent loads. In this paper, we have
used a position control model to examine changes to control
signals for arm movements in the context of movement-
dependent loads. In the model, based on the equilibrium-
point hypothesis, equilibrium shifts are adjusted directly
in proportion to the positional error between desired
and actual movements. The model is used to simulate
multi-joint movements in the presence of both internal
loads due to joint interaction torques, and externally
applied loads resulting from velocity-dependent force
fields. In both cases it is shown that the model can
achieve close correspondence to empirical data using a
simple linear adaptation procedure. An important feature
of the model is that it achieves compensation for loads
during movement without the need for either coordinate
transformations between positional error and associated
corrective forces, or inverse dynamics calculations.
A method to adjust EP control signals is proposed.
EP is characterised by monothonic shifts between postures in EP state.
However, due to internal or external loads, the desired trajectory
may deviate from the EP trajectory.
In this paper, a learning approach is modeled based on EP control.
Thereby, the deviation of desired and actual trajectory is added (after
timeshifting) to the EP trajectory.
This is possible, because according to the EP theory, the Error Signal
and the EP Signal are in the same modality and no conversion between
modalities is necessary.
This allows the formation of nonmonothonic EP trajectories and fast
adjustment of movements due to internal (interaction torques) or
external loads.
However, as noted in Gribble (1998) or Kalveram (2005), this approach
may be insufficient, because EP signal do not necessarily have the
same value as the resulting msucle length signals.
Additionally, no method of generalization or organization of the changed
trajectories is considered.
%0 Journal Article
%1 Gribble2000
%A Gribble, Paul L
%A Ostry, David J
%D 2000
%J Experimental Brain Research
%K Arm Equilibrium Human Mathematical Motor learning model movement point ·
%P 474482
%R 10.1007/s002210000547
%T Compensation for loads during arm movements using equilibrium-point
control
%V 135
%X A significant problem in motor control is how
information about movement error is used to modify control
signals to achieve desired performance. A potential
source of movement error and one that is readily controllable
experimentally relates to limb dynamics and associated
movement-dependent loads. In this paper, we have
used a position control model to examine changes to control
signals for arm movements in the context of movement-
dependent loads. In the model, based on the equilibrium-
point hypothesis, equilibrium shifts are adjusted directly
in proportion to the positional error between desired
and actual movements. The model is used to simulate
multi-joint movements in the presence of both internal
loads due to joint interaction torques, and externally
applied loads resulting from velocity-dependent force
fields. In both cases it is shown that the model can
achieve close correspondence to empirical data using a
simple linear adaptation procedure. An important feature
of the model is that it achieves compensation for loads
during movement without the need for either coordinate
transformations between positional error and associated
corrective forces, or inverse dynamics calculations.
@article{Gribble2000,
abstract = {A significant problem in motor control is how
information about movement error is used to modify control
signals to achieve desired performance. A potential
source of movement error and one that is readily controllable
experimentally relates to limb dynamics and associated
movement-dependent loads. In this paper, we have
used a position control model to examine changes to control
signals for arm movements in the context of movement-
dependent loads. In the model, based on the equilibrium-
point hypothesis, equilibrium shifts are adjusted directly
in proportion to the positional error between desired
and actual movements. The model is used to simulate
multi-joint movements in the presence of both internal
loads due to joint interaction torques, and externally
applied loads resulting from velocity-dependent force
fields. In both cases it is shown that the model can
achieve close correspondence to empirical data using a
simple linear adaptation procedure. An important feature
of the model is that it achieves compensation for loads
during movement without the need for either coordinate
transformations between positional error and associated
corrective forces, or inverse dynamics calculations.},
added-at = {2009-06-26T15:25:19.000+0200},
author = {Gribble, Paul L and Ostry, David J},
biburl = {https://www.bibsonomy.org/bibtex/261b0d480d68e9520bfb8fa3d79ed4113/butz},
description = {diverse cognitive systems bib},
doi = {10.1007/s002210000547},
interhash = {b1c687331bceb174f5c1ca4291fac72a},
intrahash = {61b0d480d68e9520bfb8fa3d79ed4113},
journal = {Experimental Brain Research},
keywords = {Arm Equilibrium Human Mathematical Motor learning model movement point ·},
owner = {martin},
pages = {474482},
review = {A method to adjust EP control signals is proposed.
EP is characterised by monothonic shifts between postures in EP state.
However, due to internal or external loads, the desired trajectory
may deviate from the EP trajectory.
In this paper, a learning approach is modeled based on EP control.
Thereby, the deviation of desired and actual trajectory is added (after
timeshifting) to the EP trajectory.
This is possible, because according to the EP theory, the Error Signal
and the EP Signal are in the same modality and no conversion between
modalities is necessary.
This allows the formation of nonmonothonic EP trajectories and fast
adjustment of movements due to internal (interaction torques) or
external loads.
However, as noted in Gribble (1998) or Kalveram (2005), this approach
may be insufficient, because EP signal do not necessarily have the
same value as the resulting msucle length signals.
Additionally, no method of generalization or organization of the changed
trajectories is considered.},
timestamp = {2009-06-26T15:25:32.000+0200},
title = {Compensation for loads during arm movements using equilibrium-point
control},
volume = 135,
year = 2000
}