TY - JOUR
T1 - Automated optimal coordination of multiple-DOF neuromuscular actions in feedforward neuroprostheses
AU - Lujan, J. Luis
AU - Crago, Patrick E.
N1 - Funding Information:
Manuscript received September 12, 2007; revised February 27, 2008 and May 5, 2008. First published July 15, 2008; current version published February 13, 2009. This work was supported by the National Institutes of Health Neural Prosthesis Program under Grant N01-NS-1-2333 and Grant N01-NS-5-2365. Asterisk indicates corresponding author. *J. L. Lujan is with Cleveland Clinic Foundation, Cleveland, OH 44195 USA (e-mail: lujanl@ccf.org).
PY - 2009/1
Y1 - 2009/1
N2 - This paper describes a new method for designing feedforward controllers for multiple-muscle, multiple-DOF, motor system neural prostheses. The design process is based on experimental measurement of the forward input/output properties of the neuromechanical system and numerical optimization of stimulation patterns to meet muscle coactivation criteria, thus resolving the muscle redundancy (i.e., overcontrol) and the coupled DOF problems inherent in neuromechanical systems. We designed feedforward controllers to control the isometric forces at the tip of the thumb in two directions during stimulation of three thumb muscles as a model system. We tested the method experimentally in ten able-bodied individuals and one patient with spinal cord injury. Good control of isometric force in both DOFs was observed, with rms errors less than 10% of the force range in seven experiments and statistically significant correlations between the actual and target forces in all ten experiments. Systematic bias and slope errors were observed in a few experiments, likely due to the neuromuscular fatigue. Overall, the tests demonstrated the ability of a general design approach to satisfy both control and coactivation criteria in multiple-muscle, multiple-axis neuromechanical systems, which is applicable to a wide range of neuromechanical systems and stimulation electrodes.
AB - This paper describes a new method for designing feedforward controllers for multiple-muscle, multiple-DOF, motor system neural prostheses. The design process is based on experimental measurement of the forward input/output properties of the neuromechanical system and numerical optimization of stimulation patterns to meet muscle coactivation criteria, thus resolving the muscle redundancy (i.e., overcontrol) and the coupled DOF problems inherent in neuromechanical systems. We designed feedforward controllers to control the isometric forces at the tip of the thumb in two directions during stimulation of three thumb muscles as a model system. We tested the method experimentally in ten able-bodied individuals and one patient with spinal cord injury. Good control of isometric force in both DOFs was observed, with rms errors less than 10% of the force range in seven experiments and statistically significant correlations between the actual and target forces in all ten experiments. Systematic bias and slope errors were observed in a few experiments, likely due to the neuromuscular fatigue. Overall, the tests demonstrated the ability of a general design approach to satisfy both control and coactivation criteria in multiple-muscle, multiple-axis neuromechanical systems, which is applicable to a wide range of neuromechanical systems and stimulation electrodes.
KW - Artificial neural networks (ANNs)
KW - Coupled DOFs feedforward control
KW - Neuroprostheses
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U2 - 10.1109/TBME.2008.2002159
DO - 10.1109/TBME.2008.2002159
M3 - Article
C2 - 19224731
AN - SCOPUS:60549088770
SN - 0018-9294
VL - 56
SP - 179
EP - 187
JO - IEEE Transactions on Biomedical Engineering
JF - IEEE Transactions on Biomedical Engineering
IS - 1
ER -