Study of IMU Mounting Position for ZUPT-Aided INS in the Case of Firefighter Crawling

We report on optimization of the inertial measurement unit (IMU) mounting position for zero velocity update (ZUPT)-aided inertial navigation systems (INS) in firefighter crawling scenarios. In this study, we considered four IMU mounting positions: (1) on the heel of the foot, (2) inside the knee, (3) outside the knee, and (4) embedded in the center of the supporting knee-pad. We focused on two methods of crawling maneuvers commonly used for performing tasks in firefighting scenarios, described as hand/knee crawling and "duck" crawling. Two performance metrics were considered: stability of the IMU during stance phase and the stance phase duration. We concluded that the optimal mounting position is in the center of the knee under the experimental conditions. This finding is supported by ten navigation trials performed over a 42.6m straight line for each of the four mounting positions and two crawling maneuvers. A circular error probable (CEP) on the order of 0.8m was demonstrated for the center-knee placement of the IMU.