Related Experiment Videos
Switching curve controller for FES-assisted standing up and sitting down
M J Dolan1, B J Andrews, P H Veltink
1Department of Orthopaedic and Trauma Surgery, University of Dundee, U.K.
IEEE Transactions on Rehabilitation Engineering : a Publication of the IEEE Engineering in Medicine and Biology Society
|June 19, 1998
Summary
A new switching curve controller (SCC) aids in Functional Electrical Stimulation (FES)-assisted sit-to-stand and stand-to-sit movements. While not improving standing, the SCC significantly enhanced safety during sitting by reducing knee angular velocity for a softer landing.
Area of Science:
- Biomedical Engineering
- Neurorehabilitation
- Biomechanics
Background:
- Functional Electrical Stimulation (FES) is a promising technology for restoring mobility in individuals with spinal cord injuries.
- Existing control strategies for FES-assisted sit-to-stand and stand-to-sit (STST) movements often lack the precision to ensure safety and prevent injuries.
- The development of robust controllers is crucial for reliable FES applications.
Purpose of the Study:
- To describe and evaluate a novel low-level, closed-loop controller, the switching curve controller (SCC), for FES-assisted STST.
- To compare the SCC's performance against an unramped, open-loop controller (OLC) in a pilot study.
- To enhance safety during STST movements by preventing knee-locking and uncontrolled seat contact.
Main Methods:
- A bang-bang controller utilizing a phase-plane trajectory model as a switching curve was designed.
- The SCC was integrated into a hierarchical, finite state control scheme.
- A pilot study was conducted on a volunteer with paraplegia, measuring vertical hand forces and knee angles during STST with both SCC and OLC.
Main Results:
- Both SCC and OLC enabled safe standing up and sitting down.
- For standing up, the SCC showed no quantifiable advantage over the OLC and increased hand force by 8.4%.
- For sitting down, the SCC reduced knee angular velocities by 27% upon approaching the seat, indicating a safer landing.
Conclusions:
- The switching curve controller (SCC) offers potential for improving safety in FES-assisted movements, particularly during the sitting phase.
- The SCC demonstrated a significant reduction in knee angular velocity during sitting, contributing to a softer and safer landing.
- Further research is warranted to explore the full potential of SCCs in FES applications for individuals with motor impairments.