Influence of different gait trajectories in an lower limb active orthosis performance based on user metabolic cost and motors usage

In active orthoses for paraplegic users, it is essential that the devices replicate the user's leg movements. This is usually performed through joint position control, where each orthosis joint follows a specific angle trajectory as a reference. The most commonly used approach for generating this required references is to create a set of average joint trajectories from a gait database, and use them as a set of default references. Although recent approaches shown improvement, the influence of a user oriented gait trajectory to the orthosis general performance is still unknown. Nevertheless, due to the complexity of human gait system and individual body reaction when wearing an active lower limb orthosis, the efficacy and performance of such devices are still in current analysis. Taking the metabolic effort realized during gait and the electric power used by the motors in consideration, this work presents a performance comparison between different types of trajectories followed by the orthosis. The metabolic effort realized by the user will be obtained through the measurement of the heart beat rate. The experiments were realized in Ortholeg orthosis with a healthy subject. The main contribution of this work is to provide information regarding the influence of different gait types an active lower limb orthosis performance, allowing a better gait trajectory planning that can be used for daily walk or for rehabilitations programs.