tailieunhanh - Human-Robot Interaction Part 10

Tham khảo tài liệu 'human-robot interaction part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Predictive Tracking in Vision-based Hand Pose Estimation using Unscented Kalman Filter and Multi-viewpoint Cameras 163 Fig. 5. The calculation of geometric error between surface model and voxel data. another by keeping track of the changes in the distance values of the selected quadrics. That way we can say that a sense of direction is encoded in the observation vector. Thus the observation vector contains the magnitude of change of the finger link s motion as well as its general sense of direction. To interpret the observation vector a zero error between the model and the observation . Y 0 implies that the hand model is completely inside the voxel data. Some value in the observation vector indicates that the fingers have moved in certain direction. Finally in Equation 13 Yk is always set to zero based on two things. First comparing the voxel data to itself and computing distance measurements will just yield zero. Second from the perspective of the filter Yk 0 can be interpreted to mean that the observation sensor measurement is not completely reliable and that we have to correct it through the Kk Yk - Y k term of Equation 13. Initialization and filter tuning Filter fine tuning and proper parameter initialization are important tasks when incorporating a predictive filter to a motion tracking solution. As mentioned above the state vector is set to zero value X0 at the initial step. The zero values assigned to the state parameters mean that the hand model is at its initial pose. The hand is said to be at initial pose when the palm is flat open and the fingers are extending away from the palm. Likewise the state covariance matrix s diagonal is set to some value P0 . The fine-tuning parameters of Ằ see Equation 3 were also determined heuristically. For example a was set to a small value between 1 and 1x10-4 K was set to 3 - n and p was set to 2. Likewise selection of the noise covariances Rk and Sk is also critical. 6. Experimental results and discussion For all