Designing optimal controls by parameter optimization for a stance-control knee-ankle-foot orthosis

Inverse dynamics simulation is often used in robotic and mechatronic systems to track a desired trajectory by feed-forward control. Musculoskeletal multibody systems are highly overactuated and show a switching number of closed kinematical loops. The method of inverse dynamics is also successfully applied to overactuated systems by parameter optimization for two- and three-dimensional models of the human musculoskeletal system. The presented simulation approach is fully based on optimizationPostprint (published version

A review of lower-limb wearable exoskeletons for overground rehabilitation

Gait disorders are common among people with neuromuscular impairments –60% of the patients– and generally have a high impact on their quality of life . Lack of physical activity increases the risk of secondary health conditions such as respiratory and cardiovascular complications, bowel/bladder dysfunction, obesity, osteoporosis and ulcers; which can further diminish life expectancy. Therefore, walking recovery is one of the main rehabilitation priorities for patients with a neuromuscular impairment. Wearable exoskeletons are emerging as a revolutionary device for gait rehabilitation, mainly due to both the active participation required from the user promoting physical activity10 and the possibility to work as an assistive device in the community. In fact, the number of research studies during the past 10 years has shown a large increase following the general tendency of rehabilitation robotics . Although wearable exoskeletons are starting to be used in clinical practice, their efficacy is still not clear. This study provides a comprehensive overview on wearable powered exoskeletons for overground rehabilitation without body weight support in people with neuromuscular impairments.Peer ReviewedPostprint (published version

Influence of the controller design on the accuracy of a forward dynamic simulation of human gait

The analysis of a captured motion can be addressed by means of forward or inverse dynamics approaches. For this purpose, a 12 segment 2D model with 14 degrees of freedom is developed and both methods are implemented using multibody dynamics techniques. The inverse dynamic analysis uses the experimentally captured motion to calculate the joint torques produced by the musculoskeletal system during the movement. This information is then used as input data for a forward dynamic analysis without any control design. This approach is able to reach the desired pattern within half cycle. In order to achieve the simulation of the complete gait cycle two different control strategies are implemented to stabilize all degrees of freedom: a proportional derivative (PD) control and a computed torque control (CTC). The selection of the control parameters is presented in this work: a kinematic perturbation is used for tuning PD gains, and pole placement techniques are used in order to determine the CTC parameters. A performance evaluation of the two controllers is done in order to quantify the accuracy of the simulated motion and the control torques needed when using one or the other control approach to track a known human walking pattern.Postprint (author's final draft

Performance evaluation of different control strategies for the forward dynamic simulation of human gait

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Estimation of muscular forces from SSA smoothed sEMG signals calibrated by inverse dynamics-based physiological static optimization

The estimation of muscular forces is useful in several areas such as biomedical or rehabilitation engineering. As muscular forces cannot be measured in vivo non-invasively they must be estimated by using indirect measurements such as surface electromyography (sEMG) signals or by means of inverse dynamic (ID) analyses. This paper proposes an approach to estimate muscular forces based on both of them. The main idea is to tune a gain matrix so as to compute muscular forces from sEMG signals. To do so, a curve fitting process based on least-squares is carried out. The input is the sEMG signal filtered using singular spectrum analysis technique. The output corresponds to the muscular force estimated by the ID analysis of the recorded task, a dumbbell weightlifting. Once the model parameters are tuned, it is possible to obtain an estimation of muscular forces based on sEMG signal. This procedure might be used to predict muscular forces in vivo outside the space limitations of the gait analysis laboratory.Postprint (published version

Lower-Limb Exosuits for Rehabilitation or Assistance of Human Movement: A Systematic Review

Background: The aim of this review is to provide a comprehensive overview of the technological state-of-the-art of exosuits and the clinical results obtained when applied to users with mobility impairment. Methods: Searches are carried out in the COCHRANE, PubMed, IEEE Xplore and MEDLINE databases. Titles, abstracts and full texts are screened for inclusion criteria. Technological and clinical data are extracted. The quality of the studies is evaluated via a study quality assessment tool. Results: 19 studies are identified as relevant. Active (47%) and passive exosuits (53%) are used. Most are used untethered (84%), accommodating the demand of mobility. No study reports power consumption, which is important for dimensioning power systems. Fields of applications are post-stroke (79%), osteoarthritis (16%) and post-trauma (5%). Mostly the ankle joint is addressed (57%), while less studies address multiple joints (21%). The outcomes of clinical evaluations of lower-limb exosuits with patients suffering from mobility impairments are positive in the correction of gait pattern and reducing metabolic energy consumption during hemiparetic walking. Conclusions: Lower-limb exosuits for clinical applications are still facing technological challenges. Fields of application are limited to stroke, osteoarthritis and trauma. While clinical outcomes are overall positive, improvements in the study protocols are suggested.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Can the use of an auditory feedback device improve the gait pattern of paediatric patients with hemiparesis?

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Design of a patient-tailored active knee-ankle-foot orthosis to assist the gait of spinal cord injured subjects

—This paper presents the main design steps in the development of an active knee-ankle-foot orthosis (KAFO) conceived to assist the gait of incomplete spinal cord injured (SCI) subjects. The design approach is based on the idea of modifying the available passive orthoses by adding adaptable mechatronic modules at the joints. This approach has resulted in a prototype that has been tested on SCI patients. The design and control problems found and their adopted solutions are thoroughly described.Postprint (published version

Some aspects of heel strike impact dynamics in the stability of bipedal locomotion

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Validación experimental de un modelo de músculo activado de forma artificial

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