EVALUATION COMMITTEE

The Faculty Council has appointed the following adjudication committee to evaluate the thesis and the associated lecture: 

• Prof. Alessandra L. G. Pedrocchi, Department of Electronics, Information and Bioengineering, Politecnico di Milano, Italy,
• Prof. Zlatko Matjačić, Faculty of Health Sciences, University of Ljubljana, Slovenia
• Dr. Carsten Dahl Mørch, HST, Aalborg University, Denmark (Chairman)

Moderator:
Dr. Erika G. Spaich, HST, Aalborg University

Abstract

Injury to the upper part of the spinal cord or to the brain results usually in upper limb weakness and reduction in hand dexterity. Wearable robots, such as hand exoskeletons, have been introduced for assisting patients in accomplishing activities of daily living or for rehabilitation purposes. Different mechanisms and methods have been developed to reduce the size and weight of the exoskeletons, while providing the hand with sufficient grasp force and dexterity to accomplish the required daily tasks. The overall objective of this Ph.D. was to develop comprehensive support for human hand movements, including finger extension and flexion, using a soft exoskeleton glove. Three different studies have been conducted to investigate tendon-based methods to actuate a hand exoskeleton for supporting hand opening and closing.

 

The first study aimed at designing, implementing, and testing a bio-inspired tendon-based mechanism to provide the fingers with natural flexion and extension motions. The mechanism mimics the tendon structure of the extrinsic muscle-tendon units in the human hand including the flexors and extensors. The design has been implemented on a fabric glove to be tested on healthy subjects. The middle finger flexion and extension trajectories have been collected and compared with voluntary flexion and extension motions. The results showed that the proposed designs are promising solutions to actuate a soft hand exoskeleton for rehabilitation and assistive purposes. 

The second study presents an under-actuated system used to drive the thumb, index and middle fingers using an actuation module based on a single motor and a mechanism of pulleys. The differential design of the mechanism allowed the fingers and the thumb to adapt to and grasp irregularly shaped objects. The kinetics of the fingers when grasping these objects was evaluated experimentally. The results showed that the mechanism provided a stable and natural grasp for irregularly shaped objects, while also providing proper distribution of contact forces across the fingers and the thumb.

In the third study, an upgraded version of the under-actuated system presented in study 2, and a human/machine interface based on EMG signals were integrated to develop a soft hand exoskeleton. The under-actuated system was implemented with differential gear sets instead of pulleys. The differential mechanism allowed the exoskeleton to perform different hand gestures including extension, power grasp, tripod grasp, lateral pinch, and index pointing. The soft hand exoskeleton was controlled intuitively using EMG signals from the extrinsic hand muscles of the user. The functionality of the exoskeleton and controller were tested by holding and manipulating versatile objects using different grasps/postures. The results proved the ability of the device to accomplish selected daily life activities and its potential to assist patients suffering from hand weakness and reduced dexterity.