Finite Time Robust Control of the Sit-to-Stand Movement for Powered Lower Limb Orthoses
This addresses safe control of assistive devices for individuals with mobility impairments, but the improvement is incremental over existing methods.
The study develops a finite-time robust control technique for powered lower limb orthoses during Sit-to-Stand movement, selecting LQR gains to minimize robust performance metrics under parameter uncertainty. Simulations show improved robustness compared to prior work.
This study presents a technique to safely control the Sit-to-Stand movement of powered lower limb orthoses in the presence of parameter uncertainty. The weight matrices used to calculate the finite time horizon linear-quadratic regulator (LQR) gain in the feedback loop are chosen from a pool of candidates as to minimize a robust performance metric involving induced gains that measure the deviation of variables of interest in a linear time-varying (LTV) system, at specific times within a finite horizon, caused by a perturbation signal modeling the variation of the parameters. Two relevant Sit-to-Stand movements are simulated for drawing comparisons with the results documented in a previous work.