1. A method for estimating movement defined by a movement vector with six variables of a solid mobile in a medium liable to generate disturbances defined by a disturbance vector with three variables, the solid being equipped with at least one acceleration sensor having at least three sensitive axes and at least one magnetic field sensor having at least three sensitive axes, the method comprising: producing a vector with nine variables including the movement vector with six variables and the disturbance vector with three variables, and weighting the vector with nine variables to transform the vector with nine variables into a vector with at most five unknown variables to be estimated.