Javier Bermejo-García

Gait monitoring using hip joint angles offers a promising approach for person identification, leveraging the capabilities of smartphone inertial measurement units (IMUs). This study investigates the use of smartphone IMUs to extract hip joint angles for distinguishing individuals based on their gait patterns. The data were collected from 10 healthy subjects (8 males, 2 females) walking on a treadmill at 4 km/h for 10 min. A sensor fusion technique that combined accelerometer, gyroscope, and magnetometer data was used to derive meaningful hip joint angles. We employed various machine learning algorithms within the WEKA environment to classify subjects based on their hip joint pattern and achieved a classification accuracy of 88.9%. Our findings demonstrate the feasibility of using hip joint angles for person identification, providing a baseline for future research in gait analysis for biometric applications. This work underscores the potential of smartphone-based gait analysis in personal identification systems.

In their survey dated 2019, the UN predicts that the population above the age of 65 will increase from 9%, to 16% by the year 2050 [1]. Ageing results in the eventual loss of muscle mass and strength, joint problems and overall slowing of movements with a greater risk of suffering falls or other such accidents. Gait assist exoskeletons can help promote active ageing in this segment of the population. Since these devices are user specific in terms of the mechanics and control required, the facility to test different parameters becomes indispensable. This work details the design and construction of a modular test bench to implement synergies in an exosuit using motors and cables, and the optimization of the control scheme to better adapt it to specific patients.

This study aims to evaluate the modifications that occur in the neuromuscular system during a walking assistance device through a wearable exoskeleton or exosuit. We propose to study the muscle activations and forces obtained by inverse dynamic analysis at different levels of exosuit actuation and anchor points, with the aim of obtaining an actuation map that will allow us to optimize both the design and the actuation of the exosuit. In addition, metabolic probes were calculated to estimate the influence of the exosuit on energy consumption. The results suggest a reduction in the muscle activations and forces exerted by the hamstring muscles of the actuated leg, especially the semitendinosus muscle and biceps femoris, compared to a non-actuated gait. In contrast, the muscle strength of the other muscles remains unchanged. Our results suggest that the configuration at 70% of femur length shows better results in reducing metabolic cost compared to the other configurations.

With ever-rising population comes a corresponding rise in people with mobility issues who have difficulty handling tasks in their daily lives. Such persons could benefit significantly from an active movement assistance device. This paper presents the design of a lower-limb exosuit designed to provide the wearer with useful gait assistance. While exoskeletons have existed for a while, soft exoskeletons or exosuits are relatively new. One challenge in the design of a gait-assistance device is the reduction of device weight. In order to facilitate this, the concept of kinematic synergies is implemented to reduce the number of actuators. In this prototype, the exosuit can actuate the hip, ankle, and knee of both legs using just one single motor, and a transmission system consisting of gears and clutches. The implementation of these synergies and their advantages are detailed in this paper, as well as preliminary tests to assess performance. This was performed by testing the exosuit worn by a subject on a treadmill while taking EMG readings and measuring cable tension produced. Significant reductions by up to 35% in certain muscle activations were observed, demonstrating the validity of this prototype for gait assistance.

Ageing results in the eventual loss of muscle mass and strength, joint problems, and overall slowing of movements, with a greater risk of suffering falls or other such accidents. The use of gait assistance exoskeletons can help in the active aging of this segment of the population. Given the user specificity of the mechanics and control these devices need, the facility used to test different design parameters is indispensable. This work deals with the modeling and construction of a modular test bench and prototype exosuit to test different mounting and control schemes for a cable-driven exoskeleton or exosuit. The test bench allows the experimental implementation of postural or kinematic synergies to assist multiple joints by using only one actuator and the optimization of the control scheme to better adapt to the characteristics of the specific patient. The design is open to the research community and it is expected to improve the design of cable-driven systems for exosuits.

A novel, synergy-based design for lower-limb, gait assistance exosuits is proposed in this paper. The general design philosophy is followed by the mathematical model that leads to the exosuit’s actuation system design from a certain set of postural synergies, which may reduce the number of total required actuators and, thus, the overall system weight and price. Cable extensions are chosen as the design variable upon which the principal component analysis is performed, given the high resulting cumulative variance that is obtained with few principal components. Expressions for the pulley radii are then derived and a general exosuit design is proposed, along with a novel transmission system that can combine any number of actuators to follow the gait movements from a synergy perspective. A basic testbench is also presented with such a transmission system implemented and an empirical set of results are shown with a varying number of actuators, proving that cable extensions and synergy-based design provide an excellent solution when reducing the number of actuation units in a walking-assistance exosuit.