Design and analysis of gyro-free inertial measurement units with different configurations

• The condition number is proposed as a criterion for configuration evaluation.
• Results of error analysis demonstrate the effectiveness of the proposed criterion.
• An unscented Kalman filter is proposed for state estimation.
• Effective error reductions are provided by the unscented Kalman filter.
• The unscented Kalman filter reduces the influence of different configurations.

This study reports a gyro-free inertial measurement unit (IMU) using solely four triaxial accelerometers. Four different configurations which are feasible for the gyro-free IMU design are presented. The condition number of the configuration matrix is proposed as a fundamental criterion for configuration evaluation. Thus, an optimal design is identified from the four configurations. A scheme is proposed to identify and compensate for deterministic errors of accelerometer measurements. Then, the propagation of stochastic errors is analyzed. Results of error analysis further demonstrate the effectiveness of the proposed criterion. An unscented Kalman filter (UKF) is proposed for state estimation. Simulation results show that not only the system state is robustly estimated, but also effective error reductions on state estimation are provided. Furthermore, the proposed UKF significantly reduces the influence of the four different configurations on state estimation.