Task-Agnostic Exoskeleton Control Supports Elderly Joint Energetics during Hip-Intensive Tasks
A new task-agnostic controller reduces biological hip work by 24.7% across walking, stairs, and sitting.
A research team from the University of Michigan, led by Jiefu Zhang and Robert D. Gregg, has published a breakthrough in assistive robotics. Their paper, 'Task-Agnostic Exoskeleton Control Supports Elderly Joint Energetics during Hip-Intensive Tasks,' details a novel AI controller that moves beyond previous exoskeletons limited to steady-state walking. The controller is inherently sensitive to joint power, allowing it to provide appropriate assistance across a variety of unpredictable, real-world movements without needing pre-programmed tasks.
The team validated the system on eight older adults performing a battery of hip-intensive activities: level walking, ramp ascent, stair climbing, and sit-to-stand transitions. The controller demonstrated high accuracy in matching the user's intended biological power profile, with a mean cosine similarity of 0.89. Crucially, it delivered significant biomechanical benefits: a 24.7% reduction in biological positive work at the hip and a 9.3% reduction for the entire lower limb. Simultaneously, it augmented peak total (biological + exoskeleton) hip power while reducing the peak biological power demand on the user.
These results present a dual benefit. By reducing the biological work required from aging muscles, the exoskeleton can enhance user endurance, potentially allowing for longer periods of activity without fatigue. Furthermore, by augmenting total power output, it increases the user's functional reserve—the extra capacity needed for challenging tasks like quickly rising from a chair or climbing stairs. This makes it a promising intervention for combating age-related mobility decline, where reduced ankle power forces compensatory, exhausting hip effort.
- The task-agnostic AI controller matched biological movement intent with 0.89 accuracy (cosine similarity) across diverse activities.
- Assistance reduced the biological work required from the wearer's hip by 24.7% and total lower-limb work by 9.3%.
- The system simultaneously augmented total power output, boosting functional reserve for demanding tasks like stair climbing.
Why It Matters
This enables practical, all-day exoskeleton use to combat age-related mobility decline, extending independence and reducing fall risk.