Evaluation of Magnetometer-Less Inertial Sensors for Static and Dynamic Spatial Orientation Estimation

This study introduces a magnetometer-free, custom-built inertial measurement unit (IMU) combined with an opensource sensor-fusion algorithm and provides a systematic experimental comparison against commercial IMUs that integrate proprietary hardware and closed-source filtering software. The main innovation lies in demonstrating that an open and fully reproducible hardware and software architecture can achieve orientation estimation accuracy comparable to that of state-of- the-art commercial solutions under both static and dynamic conditions. Experimental results show that the proposed system achieves a mean orientation error of 2.10% (0.11°), while consistently outperforming proprietary filtering approaches in static scenarios and exhibiting competitive variability during dynamic motion. Furthermore, the study presents a comprehensive benchmarking framework that analyzes the influence of sensor noise characteristics and filtering strategy on estimation performance across multiple hardware and algorithm configurations. These findings establish that custom-built IMUs paired with open-source sensor-fusion algorithms constitute a reliable, cost-effective, and transparent alternative to commercial hardware and software solutions for biomedical and engineering applications.