Kawato, Yusuke (2003-05). Multi-DOF precision positioning methodology using two-axis Hall-effect sensors. Master's Thesis. Thesis uri icon


  • A novel sensing methodology using two-axis Hall-effect sensors is proposed, where
    the absolute positioning of a device atop any magnet matrix is possible. This methodology
    has the capability of micrometer-order positioning resolution as well as unrestricted translational
    and rotational range in planar 3-DOF (degree-of-freedom) motions, with potential
    capability of measuring all 6-DOF motions. This research presents the methodology and
    preliminary experimental results of 3-DOF planar motion measurements atop a Halbach
    magnet matrix using two sets of two-axis Hall-effect sensors. Analysis of the Halbach
    magnet matrix is presented to understand the generated magnetic field. The algorithm
    uses the Gaussian least squares differential correction (GLSDC) algorithm to estimate the
    relative position and orientation from the Hall-effect sensor measurements. A recursive
    discrete-time Kalman filter (DKF) is used in combination with the GLSDC to obtain optimal
    estimates of position and orientation, as well as additional estimates of velocity and
    angular velocity, which we can use to design a multivariable controller.
    The sensor and its algorithm is implemented to a magnetic levitation (maglev) stage
    positioned atop a Halbach magnet matrix. Preliminary experimental results show its position
    resolution capability of less than 10 ?um and capable of sensing large rotations. Controllers
    were designed to close the control loop for the three planar degrees of freedom
    motion using the GLSDC outputs at a sampling frequency of 800 Hz on a Pentek 4284 digital
    signal processor (DSP). Calibration was done by comparing the laser interferometers?? and the GLSDC??s outputs to improve the positioning accuracy.

publication date

  • May 2003