Tracking Bedridden Patient Positions Using Micro-Doppler Signatures

Hospital patients who are bedridden for prolonged periods of time require routine repositioning to aid in the prevention of pressure ulcers. This necessitates repositioning the patient at various laterally inclined angles. Readjustments of a patient's position must be performed over prescribed time intervals. Keeping track of a patient's position history throughout a given day is difficult without supervising the patient. A camera may be used to monitor the patient, but this can be detrimental to his or her privacy. In this letter, we propose applying Doppler radar to monitoring a bedridden patient's movements. This approach enables a patient's repositioning to be monitored at a low cost and with better privacy than monitoring with cameras. Doppler radar was applied to a human subject emulating typical movements that a bedridden patient may exhibit. It was observed that each movement resulted in unique micro-Doppler signatures and tracking a patient's rotation using Doppler radar is feasible.