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Sensors (Basel). 2015 Jul 8;15(7):16448-65. doi: 10.3390/s150716448.

An Inertial and Optical Sensor Fusion Approach for Six Degree-of-Freedom Pose Estimation.

Author information

1
Beijing Engineering Research Center of Mixed Reality and Advanced Display, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China. wosipo007@163.com.
2
Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA. pkaz@jhu.edu.
3
Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA. tutkunsen@gmail.com.
4
Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA. sungminkim@jhu.edu.
5
Beijing Engineering Research Center of Mixed Reality and Advanced Display, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China. liuyue@bit.edu.cn.

Abstract

Optical tracking provides relatively high accuracy over a large workspace but requires line-of-sight between the camera and the markers, which may be difficult to maintain in actual applications. In contrast, inertial sensing does not require line-of-sight but is subject to drift, which may cause large cumulative errors, especially during the measurement of position. To handle cases where some or all of the markers are occluded, this paper proposes an inertial and optical sensor fusion approach in which the bias of the inertial sensors is estimated when the optical tracker provides full six degree-of-freedom (6-DOF) pose information. As long as the position of at least one marker can be tracked by the optical system, the 3-DOF position can be combined with the orientation estimated from the inertial measurements to recover the full 6-DOF pose information. When all the markers are occluded, the position tracking relies on the inertial sensors that are bias-corrected by the optical tracking system. Experiments are performed with an augmented reality head-mounted display (ARHMD) that integrates an optical tracking system (OTS) and inertial measurement unit (IMU). Experimental results show that under partial occlusion conditions, the root mean square errors (RMSE) of orientation and position are 0.04° and 0.134 mm, and under total occlusion conditions for 1 s, the orientation and position RMSE are 0.022° and 0.22 mm, respectively. Thus, the proposed sensor fusion approach can provide reliable 6-DOF pose under long-term partial occlusion and short-term total occlusion conditions.

KEYWORDS:

Extended Kalman Filter; hybrid tracking; inertial tracking; optical tracking

PMID:
26184191
PMCID:
PMC4541887
DOI:
10.3390/s150716448
[Indexed for MEDLINE]
Free PMC Article

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