Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium
Department of Control and Computer Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
Department of Management and Production Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
These authors contributed equally to this work.
Author to whom correspondence should be addressed.
Received: 28 March 2018 / Revised: 29 May 2018 / Accepted: 4 June 2018 / Published: 8 June 2018
In this work we present a lower limb haptic exoskeleton suitable for patient rehabilitation, specifically in the presence of illness on postural equilibrium. Exoskeletons have been mostly conceived to increase strength, while in this work patient compliance with postural equilibrium enhancement is embedded. This is achieved with two hierarchical feedback loops. The internal one, closing the loop on the joint space of the exoskeleton offers compliance to the patient in the neighborhood of a reference posture. It exploits mechanical admittance control in a position loop, measuring the patient’s Electro Miographical (
) signals. The problem is solved using multi variable robust control theory with a two degrees of freedom setting. A second control loop is superimposed on the first one, operating on the Cartesian space so as to guarantee postural equilibrium. It controls the patient’s Center of Gravity (
) and Zero Moment Point (
) by moving the internal loop reference. Special attention has been devoted to the mechanical multi-chain model of the exoskeleton which exploits Kane’s method using the Autolev symbolic computational environment. The aspects covered are: the switching system between single and double stance, the system’s non-holonomic nature, dependent and independent joint angles, redundancy in the torque controls and balancing weight in double stance. Physical experiments to validate the compliance method based on admittance control have been performed on an elbow joint at first. Then, to further validate the haptic interaction with the patient in a realistic situation, experiments have been conducted on a first exoskeleton prototype, while the overall system has been simulated in a realistic case study.
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MDPI and ACS Style
Menga, G.; Ghirardi, M. Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium. Robotics 2018, 7, 28.
Menga G, Ghirardi M. Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium. Robotics. 2018; 7(2):28.
Menga, Giuseppe; Ghirardi, Marco. 2018. "Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium." Robotics 7, no. 2: 28.
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