Ambulatory position and orientation tracking fusing magnetic and inertial sensing

Daniel Roetenberg, Per J. Slycke, Peter H. Veltink

    Research output: Contribution to journalArticleAcademicpeer-review

    242 Citations (Scopus)
    679 Downloads (Pure)

    Abstract

    This paper presents the design and testing of a portable magnetic system combined with miniature inertial sensors for ambulatory 6 degrees of freedom ( DOF) human motion tracking. The magnetic system consists of three orthogonal coils, the source, fixed to the body and 3-D magnetic sensors, fixed to remote body segments, which measure the fields generated by the source. Based on the measured signals, a processor calculates the relative positions and orientations between source and sensor. Magnetic actuation requires a substantial amount of energy which limits the update rate with a set of batteries. Moreover, the magnetic field can easily be disturbed by ferromagnetic materials or other sources. Inertial sensors can be sampled at high rates, require only little energy and do not suffer from magnetic interferences. However, accelerometers and gyroscopes can only measure changes in position and orientation and suffer from integration drift. By combing measurements from both systems in a complementary Kalman filter structure, an optimal solution for position and orientation estimates is obtained. The magnetic system provides 6 DOF measurements at a relatively low update rate while the inertial sensors track the changes position and orientation in between the magnetic updates. The implemented system is tested against a lab-bound camera tracking system for several functional body movements. The accuracy was about 5 mm for position and 3 degrees for orientation measurements. Errors were higher during movements with high velocities due to relative movement between source and sensor within one cycle of magnetic actuation
    Original languageEnglish
    Pages (from-to)883-890
    Number of pages8
    JournalIEEE transactions on biomedical engineering
    Volume54
    Issue number5
    DOIs
    Publication statusPublished - May 2007

    Keywords

    • Miniature inertial sensors
    • Human motion tracking
    • BSS-biomechatronics and rehabilitation technology
    • 3-D magnetic sensors
    • Accelerometers
    • Inertial sensing
    • Ambulatory position tracking
    • Kalman filter
    • Portable magnetic system
    • Orientation tracking
    • Lab-bound camera tracking system
    • Magnetic sensing
    • Gyroscopes

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