TY - JOUR
T1 - Adaptive sliding-mode controller of a lower limb mobile exoskeleton for active rehabilitation
AU - Pérez-San Lázaro, Rafael
AU - Salgado, Ivan
AU - Chairez, Isaac
N1 - Publisher Copyright:
© 2020 ISA
PY - 2021/3
Y1 - 2021/3
N2 - This study describes the design, instrumentation and control of an exoskeleton for lower limb children rehabilitation with nine degrees of freedom. Three degrees of freedom in each leg exert the movements of hip, knee and ankle in the sagittal plane, and three control the drive track system composed by a caterpillar-like robot. The control scheme presents a model free decentralized output feedback adaptive high-order sliding mode control to solve the trajectory tracking problem in each degree of freedom of the exoskeleton. A high order sliding mode differentiator estimates the unmeasured states and, by means of a dynamical state extension, it approximates the unknown dynamical model of the exoskeleton. A second-order adaptive sliding mode controller based on the super-twisting algorithm drives the exoskeleton articulations to track the proposed reference trajectories, inducing an ultimate boundedness for the tracking error. Numerical and experimental simulation results demonstrate the effect of the adaptive gain on the super-twisting control design. Such evaluations confirmed the superior tracking performance forced by the adaptive law for the controller with a smaller chattering amplitude and smaller mean tracking error.
AB - This study describes the design, instrumentation and control of an exoskeleton for lower limb children rehabilitation with nine degrees of freedom. Three degrees of freedom in each leg exert the movements of hip, knee and ankle in the sagittal plane, and three control the drive track system composed by a caterpillar-like robot. The control scheme presents a model free decentralized output feedback adaptive high-order sliding mode control to solve the trajectory tracking problem in each degree of freedom of the exoskeleton. A high order sliding mode differentiator estimates the unmeasured states and, by means of a dynamical state extension, it approximates the unknown dynamical model of the exoskeleton. A second-order adaptive sliding mode controller based on the super-twisting algorithm drives the exoskeleton articulations to track the proposed reference trajectories, inducing an ultimate boundedness for the tracking error. Numerical and experimental simulation results demonstrate the effect of the adaptive gain on the super-twisting control design. Such evaluations confirmed the superior tracking performance forced by the adaptive law for the controller with a smaller chattering amplitude and smaller mean tracking error.
KW - Active orthosis
KW - Adaptive control
KW - Decentralized control
KW - Lower limb exoskeleton
KW - Super-twisting algorithm
UR - http://www.scopus.com/inward/record.url?scp=85092895257&partnerID=8YFLogxK
U2 - 10.1016/j.isatra.2020.10.008
DO - 10.1016/j.isatra.2020.10.008
M3 - Artículo
C2 - 33077173
AN - SCOPUS:85092895257
SN - 0019-0578
VL - 109
SP - 218
EP - 228
JO - ISA Transactions
JF - ISA Transactions
ER -