Three-Degree-of-Freedom Absolute Displacement Sensor Based on Planar Magnetic Grid

To meet the demand for high precision over long-range multi-degree-of-freedom displacement measurement systems in industrial production, this paper proposed a novel three-degree-of-freedom (3-DOF) absolute displacement sensor to achieve absolute displacement measurement in the plane. The structure of the sensor consists of a moving planar magnetic grid and a fixed sensor board, multiple square permanent magnetics arranged in the plane constitute the planar magnetic grid, and the sensor board uses a matrix of Hall sensors to collect the magnetic field signals and provide the long-range absolute position measurement reference. The principle of displacement measurement in the plane 3-DOF (x, y, and R
z
) is analyzed, and the method of the long-range linear absolute displacement measurement is proposed. Finally, the experiment results demonstrate that the prototype sensor achieves 10μm resolution in the
$x$
and
$y$
directions and 0.1° angular resolution around the
$z$
direction.