Collaborative Research: Detecting Gait Phases with Raised Metabolic Cost using Robotic Perturbations and System Identification for Enabling Targeted Rehabilitation Therapy

Being able to walk easily is strongly associated with independence and quality of life. Aging is accompanied by a significant reduction in mobility. Existing treatments and therapies rely on respiratory measurements of walking effort.

These respiratory measurements can only quantify the average effort of walking. As a result of this limitation, existing treatments and therapies sometimes fail to target the phases of the walking motion that need the most assistance. This project will use data-driven approaches and models to overcome limitations in the ability to measure the effort of walking.

Access to this new information will enable evaluating how therapies affect different stages of motion. The data-driven methods will be initially developed using a dataset generated by a computer walking models with physically induced changes to specific stages of motion. For example, forward-pulling forces will be applied to the waist of the model to induce changes that can be leveraged to detect the fluctuations in walking effort.

This computer walking model provides access to a complete measure of the effort required for walking, which will be used to validate the data-driven methods. Next, the new data-driven methods will be validated using measurements from real human walking experiments. In these human experiments, pulling forces will be applied by a robotic tether connected to the waist of the participant to induce changes that will be used to detect the effort of the different motion stages.

In the final studies, the methods will be used to determine how the effort required for walking differs in younger and older adults. The differences in the effort will be characterized in each stage of motion using human experiments with both younger and older adults. The outcomes of this project will help lead to the creation of enhanced treatments and assistive devices that improve all stages of motion.

Throughout this project, the investigators will provide courses for older adults on the mechanics and health aspects of walking and data science and digital engineering through the Osher Lifelong Learning Institute.

The goal of this project is to leverage new data-driven approaches to characterize differences in metabolic cost of phases of the gait cycle in old versus young adults. The project will combine novel, data-driven approaches based on system identification and robotic perturbations to characterize the time profile of signals that cannot be measured directly, such as metabolic cost.

The first objective will produce the time profile of metabolic cost within simulated gait data. Novel data-driven approaches will be developed based on weighted regression, neural networks, and autoencoders to identify the metabolic cost time profile from biomechanical signals. Initially, these methods will be created in a predictive walking simulation from which the metabolic time profile is fully known, such that the new methods can be evaluated during their development.

The second objective will evaluate different time profile estimation approaches in human experiments. The methods created in the first objective will be tested using human experiments with robotic perturbations. The capacity of using the data-driven methods to detect changes in swing and push-off will also be investigated using human experiments where elastic ankle tethers or added mass are used to introduce direct changes to the gait cycle.

The third objective will characterize the differences in cost contributions of the phases of the gait cycle between older and younger adults. The first subtask will characterize the phase-specific differences in metabolic cost by applying the data-driven methods to compute the instantaneous costs using measured data from younger and older adults. The second subtask will determine the generalizability of the data-driven time-profile estimation approaches across different populations.

This research will transform gait analysis by providing access to dynamic metabolic cost time profiles, which cannot be measured using existing techniques. Access to this new information will lead to improvements across multiple biomechanics applications, including (1) diagnosis of motion impairments, (2) prescription of targeted assistive devices, and (3) targeted rehabilitation exercises.

This project is jointly funded by the Disability and Rehabilitation Engineering Program (DARE) and the Established Program to Stimulate Competitive Research (EPSCoR).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.