Active assistance of human locomotion through low-dimensional motor primitives

This master thesis was set in the framework of the European project CYBERLEGs PLUS PLUS whose main objective is the restoration of a more natural gait pattern to transfemoral amputees thanks to active ortho-prostheses. Furthermore, the wearable robotics modules developed by this consortium are also supposed to assist older people suffering from gait-related disorders. In this purpose, a new dynamic-based motor controller for an active pelvis module, i.e. assisting both hips, has been designed, implemented and tested on healthy subjects. This controller took inspiration from the so-called motor primitives, which are described by physiologists as a set of basic signals that through proper recombination allow to recover the different muscles stimulations needed for different locomotion tasks. However, unlike the previous works carried out by the consortium, in the present thesis new constraints were imposed in order to obtain more bio-inspired shapes which should reduce the number of parameters needed to fully describe them. After an overview of the current assistive control strategies for human locomotion and of the biological evidence for motor primitives, the methodology used here to generate these low- dimensional motor primitives is explained. Their implementation into a hips exoskeleton and some pilot studies held subsequently are then presented. Thereafter first evidence towards experimental validation is provided and the obtained results are discussed. Finally some suggestions are made to further assess the validity of the presented assistive control method and different ways of improving this human-robot interaction are proposed.