Feedback Control Design for Robust Comfortable Sit-to-Stand Motions of 3D Lower-Limb Exoskeletons

Lower-limb exoskeletons provide people who suffer from lower limb impairments with an opportunity to stand up and ambulate. Standing is a crucial task for lower-limb as it allows the user transfer exoskeleton wheelchair, no assistance, can be precursor walking. Achieving safe sit-to-stand motion + system challenging because of need balance comfort while respecting hardware bounds being robust changes in characteristics user's environment. We successfully achieve motions by using constrained optimization generate two types dynamic based on hybrid descriptions exoskeleton, Atalante. Due highly nature equations motions, we introduce method systematically design virtual constraints systems. also quadratic program-based computed-torque controllers safely come stop standing position. then analyze closed-loop behaviors under physically motivated robustness tests. The criteria used determine successful are: tracking error, pitch acceleration torso, amount force needed perform motion, adherence Zero Moment Point (ZMP), friction, joint constraints.