Limits...
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.

Show MeSH

Related in: MedlinePlus

(a) Actual velocity; (b) Simulated velocity.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4541887&req=5

sensors-15-16448-f007: (a) Actual velocity; (b) Simulated velocity.

Mentions: To determine the variance that matches the actual process noise, the data from IMU is compared with the data added by simulated noise generated in Matlab in a continuous comparison procedure until a suitable value is obtained. To implement this, the measurement of the IMU is collected for 10 s under static conditions. Figure 7 shows the velocity from the actual accelerometer data (left) and simulated data (right) for the comparison procedure of the velocity process noise. The comparison procedures of the orientation and position process noise are done with a similar method. With the adoption of this comparison procedure, the variance, which is related to orientation estimation, is set to 0.000025; the variance, which is related to position estimation, is set to 0.0002; and the variance, which is related to velocity estimation, is set to 0.00006.


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)

(a) Actual velocity; (b) Simulated velocity.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-16448-f007: (a) Actual velocity; (b) Simulated velocity.
Mentions: To determine the variance that matches the actual process noise, the data from IMU is compared with the data added by simulated noise generated in Matlab in a continuous comparison procedure until a suitable value is obtained. To implement this, the measurement of the IMU is collected for 10 s under static conditions. Figure 7 shows the velocity from the actual accelerometer data (left) and simulated data (right) for the comparison procedure of the velocity process noise. The comparison procedures of the orientation and position process noise are done with a similar method. With the adoption of this comparison procedure, the variance, which is related to orientation estimation, is set to 0.000025; the variance, which is related to position estimation, is set to 0.0002; and the variance, which is related to velocity estimation, is set to 0.00006.

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