Spacing Vector and Varying Distance Constrained Positioning Using Dual Feet-Mounted IMUs

The zero velocity update (ZUPT) offers an effective correction method for sensor drift in indoor positioning systems using foot-mounted inertial measurement units (IMUs). However, the heading drift is still a problem in positioning systems using IMUs. This article develops methods for positioning using two foot-mounted IMUs to solve this problem. The proposed method is based on the use of a time-varying distance constraint (VDC) and a spacing-vector constraint. Our methods are experimentally compared against other distance-constraint-based methods using a dataset that we collected for this purpose. The results show that our method has better control of the separation between the trajectories of the feet.