Validating a wheelchair in-seat activity tracker

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Human-Computer Interaction

Background:

• Prolonged sitting in wheelchairs increases ischial tuberosity loading, risking pressure ulcers and sepsis.
• Regular pressure offloading movements are crucial for wheelchair users but adherence is often poor.
• A system to detect and provide feedback on these movements could improve user health and clinical management.

Purpose of the Study:

• To present and validate the Wheelchair In-Seat Activity Tracker (WiSAT) system.
• To characterize weight shifts and in-seat movements for pressure ulcer prevention in wheelchair users.
• To assess WiSAT's accuracy in detecting these movements during real-world usage scenarios.

Main Methods:

• WiSAT utilizes a sensor mat placed under a wheelchair cushion to detect user movements.
• Algorithms analyze sensor data to identify weight shifts (≥30% load reduction for 15s) and in-seat movements (transient load changes).
• Validation was performed against a high-resolution interface pressure mat in manual wheelchairs.

Main Results:

• WiSAT achieved 81% precision and 80% recall for detecting weight shifts.
• In-seat movements were predicted with a mean absolute error of 22%.
• The system demonstrated sufficient accuracy in characterizing key in-seat activities.

Conclusions:

• WiSAT is a validated system capable of accurately characterizing essential in-seat activities for wheelchair users.
• The system holds potential for providing valuable feedback to users and clinicians, aiding in pressure ulcer prevention.
• Further integration and application of WiSAT can support improved mobility and health outcomes for wheelchair users.