Next Article in Journal
Kinematics of the 3(RPSP)-S Fully Spherical Parallel Manipulator by Means of Screw Theory
Previous Article in Journal
Hexapods with Plane-Symmetric Self-Motions
Article Menu
Issue 2 (June) cover image

Export Article

Open AccessArticle
Robotics 2018, 7(2), 28; https://doi.org/10.3390/robotics7020028

Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium

1,†,* and 2,†
1
Department of Control and Computer Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
2
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

Abstract

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 (EMG) 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 (COG) and Zero Moment Point (ZMP) 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. View Full-Text
Keywords: exoskeleton; haptics; compliance; admittance control; postural equilibrium; biped robotics; multi variable control exoskeleton; haptics; compliance; admittance control; postural equilibrium; biped robotics; multi variable control
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Menga, G.; Ghirardi, M. Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium. Robotics 2018, 7, 28.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Robotics EISSN 2218-6581 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top