title: Improved Leg Tracking Considering Gait Phase and Spline-Based Interpolation during Turning Motion in Walk Tests.
abstract: Falling is a common problem in the growing elderly population, and fall-risk assessment systems are needed for community-based fall prevention programs. In particular, the timed up and go test (TUG) is the clinical test most often used to evaluate elderly individual ambulatory ability in many clinical institutions or local communities. This study presents an improved leg tracking method using a laser range sensor (LRS) for a gait measurement system to evaluate the motor function in walk tests, such as the TUG. The system tracks both legs and measures the trajectory of both legs. However, both legs might be close to each other, and one leg might be hidden from the sensor. This is especially the case during the turning motion in the TUG, where the time that a leg is hidden from the LRS is longer than that during straight walking and the moving direction rapidly changes. These situations are likely to lead to false tracking and deteriorate the measurement accuracy of the leg positions. To solve these problems, a novel data association considering gait phase and a Catmull-Rom spline-based interpolation during the occlusion are proposed. From the experimental results with young people, we confirm   that the proposed methods can reduce the chances of false tracking. In addition, we verify the measurement accuracy of the leg trajectory compared to a three-dimensional motion analysis system (VICON).
authors.affiliation: School of Science for Open and Environmental Systems, Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. ayanoriyorozu@a5.keio.jp.
authors.forename: Ayanori
authors.initials: A
authors.lastname: Yorozu
authors.affiliation: Research & Development Division, Murata Machinery, Ltd., 136 Takeda-Mukaishiro-cho, Fushimi-ku, Kyoto 612-8686, Japan. toshiki.moriguchi@drw.muratec.co.jp.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Moriguchi
authors.affiliation: Department of System Design Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. takahashi@sd.keio.ac.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D000054:Acceleration; D000465:Algorithms; D003151:Community Health Centers; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D009038:Motion; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Kalman filter; data association; gait measurement; laser range sensor; spline-based interpolation; timed up and go