Robert Nakata

Wearable sensor system for monitoring body kinematics

Existing human body motion capture solutions rely on camera based systems limited to confined measurements, or Inertial Measurement Units (IMUs) prone to noise and drift, resulting in position inaccuracies. This investigation demonstrates a proof-of-concept wearable sensor system which accurately monitors human body kinematics in real-time using Radio Frequency (RF) positioning sensors combined with MEMS based IMU sensors. In certain IMU orientations, we measured an average pitch error of <; 2 degrees for the combined method, compared with 12 degrees for an IMU alone. This self-contained sensor network has applications including military training, gaming, sports and healthcare.

RF techniques for motion compensation of an Unmanned Aerial Vehicle for remote radar life sensing

Unmanned Aerial Vehicle (UAV) platforms are ideal for remote life sensing applications including military, humanitarian and post-disaster search and rescue operations. Doppler radar sensors can remotely detect human vital signs to assess triage but any sensor motion will corrupt the signal. The vital signs signal fidelity can be improved by using the Received Signal Strength Indicator (RSSI) and Radio Frequency Direction of Arrival (DOA) to compensate for the platform motion and drift via a closed loop control system that modulates the UAV Electronic Speed Controller (ESC). The measured average RF DOA error was 0.004 degrees. Motion compensation with an ultrasonic sensor was also successfully demonstrated.

Unmanned aerial vehicle platform stabilization for remote radar life sensing

Unmanned Aerial Vehicle (UAV) platforms are increasingly ubiquitous and an ideal platform for rapid deployment to conduct remote sensing. However, for radar sensors that measure the phase of the signal of interest, the platform must be stabilized to avoid signal distortion. Measurement of respiratory motion with a continuous wave Doppler radar sensor is vulnerable to platform motion and requires a stable platform and post-detection motion compensation signal processing. We have investigated feedback stabilization techniques via simulation and empirical measurements using a bench top test fixture to remove the motion noise.

Signal conditioning for UAV-radar in vital sign monitoring

A customized signal conditioning circuit has been simulated, fabricated and tested for assisting vital sign monitoring using a short distance Doppler radar installed in an unmanned aerial vehicle (UAV). Vital sign detection using UAV in real-time requires wireless transmission of baseband data to the monitoring station. Methods have been devised to achieve this goal.