Multiphase and Multivariable Linear Controllers That Account for the Joint Torques in Normal Human Walking

Objective: The objective of this paper is to investigate whether a small number of sequentially composed multivariable linear controllers can be used to recover a defining relation between the joint torques, angles, and velocities hidden in the walking data of multiple human subjects. Methods: We so...

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Bibliographic Details
Published in:IEEE transactions on biomedical engineering Vol. 67; no. 6; pp. 1573 - 1584
Main Authors: Altinkaynak, Evrim S., Roig, Gemma, Braun, David J.
Format: Journal Article
Language:English
Published: United States IEEE 01.06.2020
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
Ankle
Controllers
Couplings
Gait
Heels
Hip
Human locomotion
Integer programming
Joints (anatomy)
Knee
Legged locomotion
Mixed integer
Multiphase
multiphase and multivariable control
Multivariable control
Muscles
Torque
Variance
Walking
ISSN:0018-9294, 1558-2531, 1558-2531
Online Access:Get full text
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Summary:Objective: The objective of this paper is to investigate whether a small number of sequentially composed multivariable linear controllers can be used to recover a defining relation between the joint torques, angles, and velocities hidden in the walking data of multiple human subjects. Methods: We solve a mixed integer programming problem that defines the optimal multivariable and multiphase relation between the torques, angles, and velocities for the hip, knee, and ankle joints. Results: Using the data of seven healthy subjects, we show that the aforementioned relation can be remarkably well represented by four sequentially composed and independently activated multivariable linear controllers; the controllers account for <inline-formula><tex-math notation="LaTeX">\text{96.5}\pm \text{0.1}{\%}</tex-math></inline-formula> (mean <inline-formula><tex-math notation="LaTeX">\pm</tex-math></inline-formula> sem) of the variance in the joint torques across subjects, and <inline-formula><tex-math notation="LaTeX">\text{89.3}\pm \text{1.1}{\%}</tex-math></inline-formula> of the variance for a new subject. We further show that each controller is associated with one of the four phases of the gait cycle, separated by toe-off and heel-strike. Conclusion: The proposed controller generalizes previously developed multiphase single variable, and single phase multivariable controllers, to a multiphase multivariable controller that better explains the walking data of multiple subjects, and better generalizes to new subjects. Significance: Our result provides strong support to extend previously developed decoupled single joint controllers to coupled multijoint multivariable controllers for the control of human assistive and augmentation devices.
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ISSN:0018-9294
1558-2531
1558-2531
DOI:10.1109/TBME.2019.2940241