Patent ID: 7979179

Claim:
An computerized method for generating a pitch state signal used in control of a ground traversing vehicle, the method being of the type including: from at least three inertial sensors positioned in three or more non-collinear orientations on the vehicle, deriving three or more digital inertial orientation signals; calculating a first pitch state signal in a three-axis state estimator module based on the three or more digital inertial orientation signals; from an additional orientation sensor positioned on the vehicle, deriving an additional digital orientation signal; calculating a second pitch state signal in a single-axis state estimation based on the digital inertial orientation signals and the additional digital orientation signal; and using the first and second pitch state signals in a first slew logic estimator module providing a pitch state output signal that mediates between an output from the three-axis state estimator module and the second slew logic estimator module wherein the improvement comprises: calculating a first intermediate pitch state signal in a first single-axis estimator based on the digital inertial orientation signals; calculating a second intermediate pitch state signal in a second single-axis state estimator based on the additional digital orientation signal; and using the first and second intermediate pitch state signals in a second slew logic estimator module to provide the second pitch state signal; so that, in the presence of a fault condition associated with either one or more of the three digital inertial orientation signals or the additional digital orientation signal, the second slew logic estimator module nevertheless provides a single-axis state estimation substantially devoid of discontinuity.