Enhancing improved heuristic drift elimination for step-and-heading based pedestrian dead-reckoning systems. 
Location based services can improve the quality of patient care and increase the efficiency of the healthcare systems.  Among the different technologies that provide indoor positioning, inertial sensors based pedestrian dead-reckoning (PDR) is one of the more cost-effective solutions, but its performance is limited by drift problems.  Regarding the heading drift, some heuristics make use of the building's dominant directions in order to reduce this problem.  In this paper, we enhance the method known as improved heuristic drift elimination (iHDE) to be implemented in a Step-and-Heading (SHS) based PDR system, that allows to place the inertial sensors in almost any location of the user's body.  Particularly, wrist-worn sensors will be used.  Tests on synthetically generated and real data show that the iHDE method can be used in a SHS-based PDR without losing its heading drift reduction capability.