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

He C, Kazanzides P, Sen HT, Kim S, Liu Y - Sensors (Basel) (2015)

Bottom Line: 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.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).

View Article: PubMed Central - PubMed

Affiliation: Beijing Engineering Research Center of Mixed Reality and Advanced Display, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China. wosipo007@163.com.

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.

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Related in: MedlinePlus

Position (mm) in three-axes versus time, obtained by integration of accelerometer data. As expected, results show large errors in position as time increases.
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sensors-15-16448-f010: Position (mm) in three-axes versus time, obtained by integration of accelerometer data. As expected, results show large errors in position as time increases.

Mentions: To determine the typical drift rates for the biases and noise of the inertial sensor, an experiment is performed where we compute the orientation and position from the inertial data collected in the static experiment. The orientation is expressed as pitch, roll, and yaw angles and position on the three-axes, and the RMSE is computed by first subtracting the mean value from each set of angles and position. The resulting RMS orientation errors, expressed as pitch, roll, and yaw, are 0.0821°, 0.0495°, and 0.0917°, respectively, which characterizes the orientation error due to both sensor bias drift and noise. Obvious drifting in static position tracking results can be found in Figure 10.


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

He C, Kazanzides P, Sen HT, Kim S, Liu Y - Sensors (Basel) (2015)

Position (mm) in three-axes versus time, obtained by integration of accelerometer data. As expected, results show large errors in position as time increases.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541887&req=5

sensors-15-16448-f010: Position (mm) in three-axes versus time, obtained by integration of accelerometer data. As expected, results show large errors in position as time increases.
Mentions: To determine the typical drift rates for the biases and noise of the inertial sensor, an experiment is performed where we compute the orientation and position from the inertial data collected in the static experiment. The orientation is expressed as pitch, roll, and yaw angles and position on the three-axes, and the RMSE is computed by first subtracting the mean value from each set of angles and position. The resulting RMS orientation errors, expressed as pitch, roll, and yaw, are 0.0821°, 0.0495°, and 0.0917°, respectively, which characterizes the orientation error due to both sensor bias drift and noise. Obvious drifting in static position tracking results can be found in Figure 10.

Bottom Line: 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.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).

View Article: PubMed Central - PubMed

Affiliation: Beijing Engineering Research Center of Mixed Reality and Advanced Display, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China. wosipo007@163.com.

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.

Show MeSH
Related in: MedlinePlus