present invention takes advantages of the conditions featured in the platform dynamics and low precision mems sensor performance it should be noted that although a road vehicle is mainly used in the following description the present invention can be advantageously implemented to other types of vehicles such as vessels commercial aircrafts etc to compute platform vehicle three dimensional position the conventional precision method tracks latitude u03c6 longitude u03bb and altitude h by numerically integrate their time derivatives at a high frequency the time derivatives of latitude u03c6 are the functions of velocity v n earth north south radius of curvature r n longitude u03bb and altitude h while the time derivatives of longitude u03bb are the functions of velocity v e earth east west radius of curvature r e latitude u03c6 and altitude h the time derivative of h is simply u2212 v d note that computations of the earth north south radius of curvature r n and the earth east west radius of curvature r e take large burden meanwhile fig1 a depicts a local tangent plane with respect to a reference point that is a concept used in an ins tracking this concept allows to numerically track the northerly displacement n and the easterly displacement e by directly integrating velocities v n and v e respectively as depicted by fig1 b wherein the steps.